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Radhakrishnan S, Nair KS, Nandi S, Bajaj H. Engineering semi-permeable giant liposomes. Chem Commun (Camb) 2023; 59:13863-13866. [PMID: 37930322 DOI: 10.1039/d3cc04039a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
Giant unilamellar vesicles (GUVs) with a semi-permeable nature are prerequisites for constructing synthetic cells. Here we engineer semi-permeable GUVs by the inclusion of DOTAP lipid in vesicles. Diffusion of molecules of different charge and size across GUVs are reported. Control over size-selective permeability is demonstrated by modulating the DOTAP lipid composition in different lipid systems without reconstituting membrane proteins. Such semi-permeable GUVs have immense applications for constructing synthetic cells.
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Affiliation(s)
- Sreelakshmi Radhakrishnan
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India.
| | - Karthika S Nair
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India.
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre, Ghaziabad 201002, India
| | - Samir Nandi
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India.
| | - Harsha Bajaj
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India.
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre, Ghaziabad 201002, India
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Nair KS, Bajaj H. Advances in giant unilamellar vesicle preparation techniques and applications. Adv Colloid Interface Sci 2023; 318:102935. [PMID: 37320960 DOI: 10.1016/j.cis.2023.102935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 05/23/2023] [Accepted: 06/05/2023] [Indexed: 06/17/2023]
Abstract
Giant unilamellar vesicles (GUVs) are versatile and promising cell-sized bio-membrane mimetic platforms. Their applications range from understanding and quantifying membrane biophysical processes to acting as elementary blocks in the bottom-up assembly of synthetic cells. Definite properties and requisite goals in GUVs are dictated by the preparation techniques critical to the success of their applications. Here, we review key advances in giant unilamellar vesicle preparation techniques and discuss their formation mechanisms. Developments in lipid hydration and emulsion techniques for GUV preparation are described. Novel microfluidic-based techniques involving lipid or surfactant-stabilized emulsions are outlined. GUV immobilization strategies are summarized, including gravity-based settling, covalent linking, and immobilization by microfluidic, electric, and magnetic barriers. Moreover, some of the key applications of GUVs as biomimetic and synthetic cell platforms during the last decade have been identified. Membrane interface processes like phase separation, membrane protein reconstitution, and membrane bending have been deciphered using GUVs. In addition, vesicles are also employed as building blocks to construct synthetic cells with defined cell-like functions comprising compartments, metabolic reactors, and abilities to grow and divide. We critically discuss the pros and cons of preparation technologies and the properties they confer to the GUVs and identify potential techniques for dedicated applications.
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Affiliation(s)
- Karthika S Nair
- Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre, Ghaziabad 201002, India
| | - Harsha Bajaj
- Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre, Ghaziabad 201002, India.
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3
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Nair KS, Radhakrishnan S, Bajaj H. Dynamic Control of Functional Coacervates in Synthetic Cells. ACS Synth Biol 2023. [PMID: 37337618 DOI: 10.1021/acssynbio.3c00249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2023]
Abstract
Membrane-less compartments formed via liquid-liquid phase separation (LLPS) are regulated dynamically via enzyme reactions in cells. Giant unilamellar vesicles (GUVs) provide a promising chassis to control, mimic, and understand the LLPS process; however, they are challenging to construct. Here, we engineer the dynamic assembly and disassembly of LLPS compartments using complex coacervates as models inside synthetic cells. Semipermeable GUVs constructed with defined lipid composition encapsulate the biomolecules, including enzymes required to regulate coacervates. Assembly and disassembly of coacervates are triggered in independent systems by the diffusion of substrates through the membrane into the vesicle lumen. The coupling of enzyme networks in a single synthetic cell system allows for reversible and out-of-equilibrium regulation of coacervates. The functional properties of the coacervates are revealed by sequestering biomolecules, including drugs and enzymes. GUVs, with functional LLPS compartment assembly, open avenues in constructing programmable autonomous synthetic cells with membrane-less organelles. The coacervate-in-vesicle platform has significant implications for understanding LLPS regulation mechanisms in cells.
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Affiliation(s)
- Karthika S Nair
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre, Ghaziabad 201002, India
| | - Sreelakshmi Radhakrishnan
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India
| | - Harsha Bajaj
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre, Ghaziabad 201002, India
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Abstract
The construction of bacterial outer membrane models with native lipids like lipopolysaccharide (LPS) is a barrier to understanding antimicrobial permeability at the membrane interface. Here, we engineer bacterial outer membrane (OM)-mimicking giant unilamellar vesicles (GUVs) by constituting LPS under different pH conditions and assembled GUVs with controlled dimensions. We quantify the LPS reconstituted in GUV membranes and reveal their arrangement in the leaflets of the vesicles. Importantly, we demonstrate the applications of OM vesicles by exploring antimicrobial permeability activity across membranes. Model peptides, melittin and magainin-2, are examined where both peptides exhibit lower membrane activity in OM vesicles than vesicles devoid of LPS. Our findings reveal the mode of action of antimicrobial peptides in bacterial-membrane-mimicking models. Notably, the critical peptide concentration required to elicit activity on model membranes correlates with the cell inhibitory concentrations that revalidate our models closely mimic bacterial membranes. In conclusion, we provide an OM-mimicking model capable of quantifying antimicrobial permeability across membranes.
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Affiliation(s)
- Samir Nandi
- Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India
| | - Karthika S Nair
- Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre, Ghaziabad 201002, India
| | - Harsha Bajaj
- Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre, Ghaziabad 201002, India
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Krishnan R S, Jana K, Shaji AH, Nair KS, Das AD, Vikraman D, Bajaj H, Kleinekathöfer U, Mahendran KR. Assembly of transmembrane pores from mirror-image peptides. Nat Commun 2022; 13:5377. [PMID: 36104348 PMCID: PMC9474448 DOI: 10.1038/s41467-022-33155-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 09/05/2022] [Indexed: 11/18/2022] Open
Abstract
Tailored transmembrane alpha-helical pores with desired structural and functional versatility have promising applications in nanobiotechnology. Herein, we present a transmembrane pore DpPorA, based on the natural pore PorACj, built from D-amino acid α-helical peptides. Using single-channel current recordings, we show that DpPorA peptides self-assemble into uniform cation-selective pores in lipid membranes and exhibit properties distinct from their L-amino acid counterparts. DpPorA shows resistance to protease and acts as a functional nanopore sensor to detect cyclic sugars, polypeptides, and polymers. Fluorescence imaging reveals that DpPorA forms well-defined pores in giant unilamellar vesicles facilitating the transport of hydrophilic molecules. A second D-amino acid peptide based on the polysaccharide transporter Wza forms transient pores confirming sequence specificity in stable, functional pore formation. Finally, molecular dynamics simulations reveal the specific alpha-helical packing and surface charge conformation of the D-pores consistent with experimental observations. Our findings will aid the design of sophisticated pores for single-molecule sensing related technologies. Alpha-helix nanopores have a range of potential applications and the inclusion of non-natural amino acids allows for modification. Here, the authors report on the creation of alpha-helix pores using D-amino acids and show the pores formed, have different properties to the L-counterparts and were resistant to proteases.
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Nair KS, Raj NB, Nampoothiri KM, Mohanan G, Acosta-Gutiérrez S, Bajaj H. Curved membrane structures induced by native lipids in giant vesicles. J Colloid Interface Sci 2021; 611:397-407. [PMID: 34963074 DOI: 10.1016/j.jcis.2021.12.098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/14/2021] [Accepted: 12/15/2021] [Indexed: 10/19/2022]
Abstract
Native lipids in cell-membrane support crucial functions like intercell communication via their ability to deform into curved membrane structures. Cell membrane mimicking Giant unilamellar vesicles (GUV) is imperative in understanding native lipid's role in membrane transformation however remains challenging to assemble. We construct two giant vesicle models mimicking bacterial inner-membrane (IM) and outer-membrane (OM) under physiological conditions using single-step gel-assisted lipid swelling. IM vesicles composed of native bacterial lipids undergo small-scale membrane remodeling into bud and short-nanotube structures. In contrast, OM vesicles asymmetrically assembled from Lipopolysaccharide (LPS) and bacterial lipids underwent global membrane deformation under controlled osmotic stress. Remarkably, highly-curved structures mimicking cell-membrane architectures, including daughter vesicle networks interconnected by necks and nano-tubes ranging from micro to nanoscale, are generated in OM vesicles at osmotic stress comparable to that applied in IM vesicles. Further, we provide a quantitative description of the membrane structures by experimentally determining membrane elastic parameters, i.e., neck curvature and bending rigidity. We can conclude that a larger spontaneous curvature estimated from the neck curvature and softer membranes in OM vesicles is responsible for large-scale deformation compared to IM vesicles. Our findings will help comprehend the shape dynamics of complex native bacterial lipid membranes.
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Affiliation(s)
- Karthika S Nair
- Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India
| | - Neethu B Raj
- Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India
| | - K Madhavan Nampoothiri
- Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre, Ghaziabad 201002, India
| | - Gayathri Mohanan
- Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India
| | - Silvia Acosta-Gutiérrez
- Department of Chemistry, Institute of Structural and Molecular Biology, University College London, UK.
| | - Harsha Bajaj
- Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre, Ghaziabad 201002, India.
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Raj NB, Nair KS, Bajaj H. Giant Vesicles Mimicking Outer Membrane of Gram-Negative Bacterium. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Mohanan G, Nair KS, Nampoothiri KM, Bajaj H. Engineering bio-mimicking functional vesicles with multiple compartments for quantifying molecular transport. Chem Sci 2020; 11:4669-4679. [PMID: 34122921 PMCID: PMC8159255 DOI: 10.1039/d0sc00084a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Controlled design of giant unilamellar vesicles under defined conditions has vast applications in the field of membrane and synthetic biology. Here, we bio-engineer bacterial-membrane mimicking models of controlled size under defined salt conditions over a range of pH. A complex bacterial lipid extract is used for construction of physiologically relevant Gram-negative membrane mimicking vesicles whereas a ternary mixture of charged lipids (DOPG, cardiolipin and lysyl-PG) is used for building Gram-positive bacterial-membrane vesicles. Furthermore, we construct stable multi-compartment biomimicking vesicles using the gel-assisted swelling method. Importantly, we validate the bio-application of the bacterial vesicle models by quantifying diffusion of chemically synthetic amphoteric antibiotics. The transport rate is pH-responsive and depends on the lipid composition, based on which a permeation model is proposed. The permeability properties of antimicrobial peptides reveal pH dependent pore-forming activity in the model vesicles. Finally, we demonstrate the functionality of the vesicles by quantifying the uptake of membrane-impermeable molecules facilitated by embedded pore-forming proteins. We suggest that the bacterial vesicle models developed here can be used to understand fundamental biological processes like the peptide assembly mechanism or bacterial cell division and will have a multitude of applications in the bottom-up assembly of a protocell. Giant vesicle functional models mimicking a bacterial membrane under physiological conditions are constructed.![]()
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Affiliation(s)
- Gayathri Mohanan
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST) Trivandrum 695019 Kerala India
| | - Karthika S Nair
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST) Trivandrum 695019 Kerala India
| | - K Madhavan Nampoothiri
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST) Trivandrum 695019 Kerala India
| | - Harsha Bajaj
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST) Trivandrum 695019 Kerala India
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Konopka AR, Asante A, Lanza IR, Robinson MM, Johnson ML, Dalla Man C, Cobelli C, Amols MH, Irving BA, Nair KS. Defects in mitochondrial efficiency and H2O2 emissions in obese women are restored to a lean phenotype with aerobic exercise training. Diabetes 2015; 64:2104-15. [PMID: 25605809 PMCID: PMC4439568 DOI: 10.2337/db14-1701] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 01/13/2015] [Indexed: 01/06/2023]
Abstract
The notion that mitochondria contribute to obesity-induced insulin resistance is highly debated. Therefore, we determined whether obese (BMI 33 kg/m(2)), insulin-resistant women with polycystic ovary syndrome had aberrant skeletal muscle mitochondrial physiology compared with lean, insulin-sensitive women (BMI 23 kg/m(2)). Maximal whole-body and mitochondrial oxygen consumption were not different between obese and lean women. However, obese women exhibited lower mitochondrial coupling and phosphorylation efficiency and elevated mitochondrial H2O2 (mtH2O2) emissions compared with lean women. We further evaluated the impact of 12 weeks of aerobic exercise on obesity-related impairments in insulin sensitivity and mitochondrial energetics in the fasted state and after a high-fat mixed meal. Exercise training reversed obesity-related mitochondrial derangements as evidenced by enhanced mitochondrial bioenergetics efficiency and decreased mtH2O2 production. A concomitant increase in catalase antioxidant activity and decreased DNA oxidative damage indicate improved cellular redox status and a potential mechanism contributing to improved insulin sensitivity. mtH2O2 emissions were refractory to a high-fat meal at baseline, but after exercise, mtH2O2 emissions increased after the meal, which resembles previous findings in lean individuals. We demonstrate that obese women exhibit impaired mitochondrial bioenergetics in the form of decreased efficiency and impaired mtH2O2 emissions, while exercise effectively restores mitochondrial physiology toward that of lean, insulin-sensitive individuals.
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Affiliation(s)
- Adam R Konopka
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition Research, Mayo Clinic College of Medicine, Rochester, MN
| | - Albert Asante
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition Research, Mayo Clinic College of Medicine, Rochester, MN
| | - Ian R Lanza
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition Research, Mayo Clinic College of Medicine, Rochester, MN
| | - Matthew M Robinson
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition Research, Mayo Clinic College of Medicine, Rochester, MN
| | - Matthew L Johnson
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition Research, Mayo Clinic College of Medicine, Rochester, MN
| | - Chiara Dalla Man
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Claudio Cobelli
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Mark H Amols
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition Research, Mayo Clinic College of Medicine, Rochester, MN
| | - Brian A Irving
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition Research, Mayo Clinic College of Medicine, Rochester, MN
| | - K S Nair
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition Research, Mayo Clinic College of Medicine, Rochester, MN
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Johnson ML, Nair KS. Assessment of old and new proteins: a novel methodology. Nutr Metab Cardiovasc Dis 2013; 23 Suppl 1:S6-S11. [PMID: 22784971 PMCID: PMC3537901 DOI: 10.1016/j.numecd.2012.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 05/02/2012] [Accepted: 05/04/2012] [Indexed: 11/18/2022]
Abstract
Protein modifications and the accumulation of those proteins are implicated in a host of diseases from Parkinson's and Alzheimer's to both insulin independent and insulin dependent diabetes mellitus. Accumulation of irreversibly modified proteins occurs when the degradation rate of proteins is reduced or the rate of modification increases. Although the synthesis rates of individual proteins in vivo have been extensively studied the methodology to measure degradation rates of individual proteins in vivo remains to be well developed. However, the ability to measure the relative age of a particular protein pool in relation to the quality of the pool (amount of damage) is a recent advance. This brief review describes a novel methodology to simultaneously measure the synthesis rate of individual proteins along with the accumulation of oxidative damage to those proteins in vivo. The results of a recent investigation on individuals with type 1 diabetes mellitus are described. Accelerated damage to de novo synthesized ApoA-1 is shown during short-term insulin cessation, which has potential clinical implications. Future implications of the novel method in diabetes and aging are also discussed.
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Affiliation(s)
- M L Johnson
- Mayo Clinic, Division of Endocrinology, 200 First Street SW, Joseph 5-194, Rochester, MN 55905, USA.
| | - K S Nair
- Mayo Clinic, Division of Endocrinology, 200 First Street SW, Joseph 5-194, Rochester, MN 55905, USA.
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Raj S, Piang LK, Nair KS, Tiwari VK, Kaur H, Singh B. Awareness regarding risk factors, symptoms and treatment facilities for cancer in selected states of India. Asian Pac J Cancer Prev 2013; 13:4057-62. [PMID: 23098516 DOI: 10.7314/apjcp.2012.13.8.4057] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE To study the level of awareness and knowledge about cancers and associated risk factors among households in selected states of India. METHODS In the study 3070 households were interviewed from six states viz, West Bengal, Kerala, Madhya Pradesh, Rajasthan and Mizoram. RESULTS Knowledge of cancers other than those related to tobacco was very low (prostate 8%, colon 11% ) among the communities, with a poor awareness of warning signs and symptoms. The knowledge varied from state to state. It is found that the major source of information related to cancers was television (38%) followed by friends and relatives (36%). Only about 15 % of respondents had knowledge about cancer awareness camps organized in their districts but they did not have knowledge about the organizers of the camp. Findings suggested a strong need for strengthening of DCCP. CONCLUSION It is important to create awareness among community through educational programs on cancer prevention, preventable cancer risk factors, benefits of early diagnosis, and availability of screening facilities. Integration of District Cancer Control activities with NRHM could be the most cost-effective strategy to prevent cancers and rural population.
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Affiliation(s)
- Sherin Raj
- National Institute of Health and Family Welfare, New Delhi, India.
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Nair KS, Piang LLK, Tiwari VK, Raj S, Nandan D. Prevention of vertical transmission of HIV in India through service integration: lessons from Mysore District, Karnataka. WHO South East Asia J Public Health 2013; 2:121-127. [PMID: 28612771 DOI: 10.4103/2224-3151.122949] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Meeting the needs of HIV-positive pregnant women and their offspring is critical to India's political and financial commitment to achieving universal access to HIV prevention, treatment, care and support. This review of the strategy to prevent vertical transmission of HIV in Mysore district, Karnataka, highlights the need to integrate prevention of parent-to-child transmission (PPTCT) and reproductive and child health (RCH) services. All key officials who were involved in the integration of services at the state and district levels were interviewed by use of semistructured protocols. Policy documents and guidelines issued by the Department of Health and Family Welfare and Karnataka State AIDS Prevention Society were reviewed, as were records and official orders issued by the office of District Health and Family Welfare Officer and District HIV/AIDS Programme Office, Mysore. Routine data were also collected from all health facilities. This review found that 4.5 years of PPTCT-RCH integration resulted not only in a rise in antenatal registrations but also in almost all pregnant women counselled during antenatal care undergoing HIV tests. Based on the findings, we propose recommendations for successful replication of this strategy. Integration of PPTCT services with RCH should take place at all levels - policy, administration, facility and community. The increased demand for HIV counselling and testing resulting from service integration must be met by skilled human resources, sufficient facilities and adequate funds at the facility level.
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Affiliation(s)
- K S Nair
- National Institute of Health and Family Welfare, Jawaharlal Nehru University, New Delhi, India
| | - L L K Piang
- Centre for Study of Social Systems, Jawaharlal Nehru University, New Delhi, India
| | - V K Tiwari
- National Institute of Health and Family Welfare, Jawaharlal Nehru University, New Delhi, India
| | - Sherin Raj
- National Institute of Health and Family Welfare, Jawaharlal Nehru University, New Delhi, India
| | - Deoki Nandan
- National Institute of Health and Family Welfare, Jawaharlal Nehru University, New Delhi, India
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Irving BA, Lanza IR, Henderson GC, Weymiller A, Sun Y, Nair KS. Endurance (ET), Resistance (RT), and Combined (CT) Training Increase Mixed Muscle Protein Synthesis Independently of Age. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1149.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Kutty RS, Nair KS. Abstract P310: Delayed Discharge in Cardiothoracic Surgical Practice - Do Our Patients Just Not Want to Go Home? Circ Cardiovasc Qual Outcomes 2011. [DOI: 10.1161/circoutcomes.4.suppl_1.ap310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Aims:
Patient discharge after non-emergent adult cardiac surgery is influenced by many medical and social factors. Delayed discharge is often due to identifiable and rectifiable factors. This resultant shortened hospital stay allows for more patients to be treated along with lower economic costs incurred in hospital. Patient care guidelines developed enable uniformity of care along with improved efficiency of care.
Methods:
Prospective analysis of data collected at a tertiary level cardiac centre (over 2000 cases/year) in 2008 of urgent and elective adult cardiac surgical cases was compared to UK national length of stay published data. Type of operation, postoperative progress along with factors influencing discharge (physiotherapy, discharge destination, etc) and length of stay were reviewed with weaknesses identified and improvements instituted. Savings of even 1 day/patient produces over $1 million/year to the hospital.
Results:
Data on 220 consecutive admisisons collected (11%, 220 of 2004) of which 175 (80%) were elective and 45 (20%) urgent. Their mean age was 68, BMI 28.6 and 163 (74%) were male. Their mean EuroSCORE was 5.18 with a log EuroSCORE was 6.61%. CABG, valve repair/replacement or a combination of the two accounted for 195 (89%) with complex procedures in the remainder. There were 5 deaths (2%). Mean critical care stay was 2 days with postoperative checks completed between days 4-6. Length of stay (days) noted to be 8.7, 7.9, 8.2 and 12.0 in all, CABG, isolated valve and valve plus grafts respectively. This discharge data was keeping with national data. Clinician related variation in postoperative progress, limitations in carer availability, anticoagulation services, weekend physiotherapy services were identified as limiting factors.
Conclusions:
Delayed discharge is multi-factorial. Our patient population is older with complex surgical problems with identifiable factors that delay discharge. Improved preoperative work-up, with planned convalescence options are essential to efficient care. Protocol driven progress, improved staffing, coordination with local teams, improved physiotherapy cover with a dedicated cardiac surgery discharge coordinator are improvements developed since this review.
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Affiliation(s)
| | - K S Nair
- Papworth Hosp, Cambridge, United Kingdom
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15
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Irving BA, Lanza I, Henderson G, Weymiller A, Schimke J, Morse D, Nair KS. Effect of exercise training modality on skeletal muscle mitochondrial biogenesis in young and older adults. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.1107.20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | | | | | - K S Nair
- EndocrinologyMayo ClinicRochesterMN
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Vendelbo MH, Nair KS. Mitochondrial longevity pathways. Biochim Biophys Acta 2011; 1813:634-44. [PMID: 21295080 DOI: 10.1016/j.bbamcr.2011.01.029] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 01/18/2011] [Accepted: 01/19/2011] [Indexed: 12/31/2022]
Abstract
Average lifespan has increased over the last centuries, as a consequence of medical and environmental factors, but maximal life span remains unchanged. Better understanding of the underlying mechanisms of aging and determinants of life span will help to reduce age-related morbidity and facilitate healthy aging. Extension of maximal life span is currently possible in animal models with measures such as genetic manipulations and caloric restriction (CR). CR appears to prolong life by reducing oxidative damage. Reactive oxygen species (ROS) have been proposed to cause deleterious effects on DNA, proteins, and lipids, and generation of these highly reactive molecules takes place in the mitochondria. But ROS is positively implicated in cellular stress defense mechanisms and formation of ROS a highly regulated process controlled by a complex network of intracellular signaling pathways. There are endogenous anti-oxidant defense systems that have the potential to partially counteract ROS impact. In this review, we will describe pathways contributing to the regulation of the age-related decline in mitochondrial function and their impact on longevity. This article is part of a Special Issue entitled Mitochondria: the deadly organelle.
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Affiliation(s)
- M H Vendelbo
- Division of endocrinology, Endocrine research Unit, The Mayo Clinic, 200 1st Street SW Joseph 5-194, Rochester, MN 55905, USA
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Srivastava DK, Prakash S, Adhish V, Nair KS, Gupta S, Nandan D. A study of interface of ASHA with the community and the service providers in Eastern Uttar Pradesh. Indian J Public Health 2009; 53:133-136. [PMID: 20108875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023] Open
Abstract
OBJECTIVE To study the functioning of ASHA in the community with special focus on interface with community and service providers in Eastern Uttar Pradesh. METHODS This was a descriptive cross-sectional study conducted in two blocks each in Gorakhpur and Maharajganj districts of Eastern Uttar Pradesh during October-December 2008. A multi stage sampling design was used. The study subjects included 120 mothers, 60 ASHAs, 20 AWWs, 20 ANMs, 4 Medical Officers in charge, 2 Chief Medical Officers (CMOs) and PRI members. Data was collected through pre-designed and pre-tested structured interview schedules and through checklists for FGDs. RESULTS Most (95%) of the ASHAs were 8th Pass or above. The residential status and marital status was as per guidelines. Induction training was received by all. Major motivating factor for ASHAs were either money (81.66%) or getting a government job (66.66%). Most of the ASHAs (86.66%) got the support from their supervisors in solving their problem and majority of them (95%) were satisfied with their supervisors. All the ASHAs have been accepted very well in the community and are acting a good link between community and health providers. The faith and confidence of community on ASHAs are reflected by the demand of additional jobs like help in getting widow pension and ration card etc. CONCLUSION Though accepted by the community, ASHAs need regular training, support and cooperation from other functionaries.
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Singh CM, Jain PK, Nair KS, Kumar P, Dhar N, Nandan D. Assessment of utilization of untied fund provided under the national rural health mission in Uttar Pradesh. Indian J Public Health 2009; 53:137-142. [PMID: 20108876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023] Open
Abstract
OBJECTIVES To seek opinion regarding the procurement and spending of untied fund provided to health centers and Village Health and Sanitation Committees (VHSCs) in selected districts in the state of Uttar Pradesh. METHODS It was a cross sectional descriptive study conducted during September-December 2008. The multi-stage random sampling technique was adopted to select the districts, health facilities and VHSCs. The data was collected using semi structured interview schedule, Focus Group Discussions (FGDs) with ANMs for qualitative information, review of the records of health centers and VHSCs. RESULTS The concept of untied fund was perceived to be a very good one at all levels. Guideline for utilization of untied fund was either not available or if available, was not clear to concerned personnel. The decision of expenditure of untied funds of CHCs and PHCs was taken in the meeting of Rogi Kalyan Samiti (RKS), but members from other sectors such as PRI, education, revenue department etc. usually did not attend the meeting. Most of Medical Officer in charges (MOICs) were not aware regarding availability of untied fund. About 50% of ANMs were not able to expend the money due to non co-operation of Pradhan. In majority of the cases the decision regarding the utilization of untied fund was taken by ANM herself instead of VHSC meeting. CONCLUSION Regular update and orientation to the service providers about the untied fund and its efficient utilization, strict monitoring of utilization of untied fund at each and every level is needed.
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Pal DK, Toppo M, Gupta S, Nair KS, Khattar P, Nandan D. A rapid appraisal of functioning of district programme management units under NRHM in Madhya Pradesh. Indian J Public Health 2009; 53:151-156. [PMID: 20108879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023] Open
Abstract
OBJECTIVES To study the functioning of District Programme Management Units in the delivery of health services in various districts of Madhya Pradesh. METHODOLOGY A cross-sectional descriptive study was conducted in seven districts of Madhya Pradesh selected randomly. The study subjects were Chief Medical and Health Officers, programme managers, assistant managers and data officers at state and district levels. Datawas collected from the respondents in a pre-designed, pre-tested in-depth interview schedule. RESULTS Around 70% of districts submitted their Programme Implementation Plan (PIP) on time, 30% were unable to do so because of inadequate staff and frequent changing of the reporting format. The District Programme Managers (DPMs) were not satisfied with their fixed salary. But they were satisfied with their job. In some districts the space available for the functioning of District Programme Management Unit (DPMU) are rather too small. CONCLUSION Standardized uniform formats and guidelines should be made available to all DPMUs at the beginning of planning process. A comprehensive pre-service training for the DPMU staff including practical sessions, field exposure on district health planning, financial management, technical and administrative issues needs to be ensured.
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Affiliation(s)
- D K Pal
- Community Medicine, Gandhi Medical College, Bhopal
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Deshmukh A, Salehzadeh F, Metayer-Coustard S, Fahlman R, Nair KS, Al-Khalili L. Post-transcriptional gene silencing of ribosomal protein S6 kinase 1 restores insulin action in leucine-treated skeletal muscle. Cell Mol Life Sci 2009; 66:1457-66. [PMID: 19266162 DOI: 10.1007/s00018-009-8818-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Excessive nutrients, especially amino acids, impair insulin action on glucose metabolism in skeletal muscle. We tested the hypothesis that the branched-chain amino acid leucine reduces acute insulin action in primary myotubes via a negative feedback mechanism involving ribosomal protein S6 kinase 1 (S6K1). The effect of S6K1 on glucose metabolism was determined by applying RNA interference (siRNA). Leucine (5 mM) reduced glucose uptake and incorporation to glycogen by 13% and 22%, respectively, compared to the scramble siRNA-transfected control at the basal level. Leucine also reduced insulin-stimulated Akt phosphorylation, glucose uptake and glucose incorporation to glycogen (39%, 39% and 37%, respectively), and this reduction was restored after S6K1 silencing. Depletion of S6K1 enhanced basal glucose utilization and protected against the development of impaired insulin action, in response to excessive leucine. In conclusion, S6K1 plays an important role in the regulation of insulin action on glucose metabolism in skeletal muscle.
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Affiliation(s)
- A Deshmukh
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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Moller N, Jensen MD, Rizza RA, Andrews JC, Nair KS. Renal amino acid, fat and glucose metabolism in type 1 diabetic and non-diabetic humans: effects of acute insulin withdrawal. Diabetologia 2006; 49:1901-8. [PMID: 16718465 DOI: 10.1007/s00125-006-0287-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Accepted: 03/12/2006] [Indexed: 10/24/2022]
Abstract
AIMS/HYPOTHESIS The aim of this study was to test the hypothesis that type 1 diabetes alters renal amino acid, glucose and fatty acid metabolism. MATERIALS AND METHODS We studied five C-peptide-negative, type 1 diabetic subjects during insulin replacement (glucose 5.6 mmol/l) and insulin deprivation (glucose 15.5 mmol/l) and compared them with six non-diabetic subjects. Leucine, phenylalanine, tyrosine, glucose and palmitate tracers were infused after an overnight fast and samples were obtained from the renal vein, femoral vein and femoral artery. RESULTS Insulin deprivation significantly increased whole-body fluxes (20-25%) of phenylalanine, tyrosine and leucine, and leucine oxidation (50%). Kidney contributed 5-10% to the whole-body leucine and phenylalanine flux. A net uptake of phenylalanine, conversion of phenylalanine to tyrosine (5 micromol/min) and net release of tyrosine (approximately 5 micromol/min) occurred across the kidney. Whole-body (three-fold) and leg (two-fold) leucine transamination increased but amino acid metabolism in the kidney did not alter with diabetes or insulin deprivation. Insulin deprivation doubled endogenous glucose production, renal glucose production was unaltered by insulin deprivation and diabetes (ranging between 100 and 140 micromol/min). Renal palmitate exchange was unaltered by insulin deprivation. CONCLUSIONS/INTERPRETATION In conclusion, kidney post-absorptively accounts for 5-10% of whole-body protein turnover, 15-20% of leucine transamination and 10-15% of endogenous glucose production, and actively converts phenylalanine to tyrosine. During insulin deprivation, leg becomes a major site for leucine transamination but insulin deprivation does not affect renal phenylalanine, leucine, palmitate or glucose metabolism. Despite its key metabolic role, insulin deprivation in type 1 diabetic patients does not alter many of these metabolic functions.
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Affiliation(s)
- N Moller
- Endocrine Research Unit, Mayo Clinic College of Medicine, 200 First Street SW, 5-194 Joseph, Rochester, MN 55905, USA
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Freyse EJ, Fischer U, Knospe S, Ford GC, Nair KS. Differences in protein and energy metabolism following portal versus systemic administration of insulin in diabetic dogs. Diabetologia 2006; 49:543-51. [PMID: 16447053 DOI: 10.1007/s00125-005-0062-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2005] [Accepted: 08/22/2005] [Indexed: 10/25/2022]
Abstract
AIMS/HYPOTHESIS In non-diabetic people, insulin levels in the liver are two-fold higher than those in the systemic circulation. In contrast, patients with type 1 diabetes have similar hepatic and systemic insulin levels because insulin is administered peripherally. The aim of this study was to compare the effects of systemic (SI) and pre-portal (PI) insulin administration on energy, glucose and protein metabolism in chronic insulin-dependent ketosis-prone diabetic dogs. MATERIALS AND METHODS We applied glucose-controlled insulin infusion, indirect calorimetry and stable isotope and radioisotope techniques to measure energy, protein and glucose metabolism. We maintained near-normoglycaemia at identical levels under both study conditions for 20 h. RESULTS SI was associated with lower oxygen consumption (130+/-13 vs 161+/-8 ml/min), CO(2) production (99+/-10 vs 130+/-8 ml/min), respiratory quotient (0.76+/-0.02 vs 0.81+/-0.01) and energy expenditure (870+/-90 vs 1089+/-60 kcal/24 h) (p<0.05 for all differences). PI increased the respiratory quotient from the insulin-deprived state, whereas SI did not. Glucose kinetics were similar for SI and PI, whereas leucine oxidation (36+/-4 vs 54+/-5 micromol kg(-1) min(-1)) and the fractional synthesis rates of liver tissue protein (0.68+/-0.6 vs 0.83+/-0.07%/h), albumin (0.55+/-0.06 vs 0.68+/-0.4%/h), and fibrinogen (1.73+/-0.23 vs 2.59+/-0.25%/h) were all lower during SI than PI (p<0.05). CONCLUSIONS/INTERPRETATION The route of insulin administration did not alter glucose metabolism but did affect protein synthesis in the liver. The potential impact of this altered liver protein metabolism on chronic complications needs careful evaluation. A similar decrease in energy expenditure resulting from systemic insulin administration during tight glycaemic control is a potential cause of weight gain.
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Affiliation(s)
- E-J Freyse
- Gerhardt Katsch Institute of Diabetes, 17495 Karlsburg, Germany
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Paxton S, Gonzales G, Uppakaew K, Abraham KK, Okta S, Green C, Nair KS, Merati TP, Thephthien B, Marin M, Quesada A. AIDS-related discrimination in Asia. AIDS Care 2005; 17:413-24. [PMID: 16036226 DOI: 10.1080/09540120412331299807] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The Asia Pacific Network of People Living with HIV/AIDS (APN+) conducted the first regional documentation of AIDS-related discrimination in Asia. This project was an action-based, peer-implemented study that aimed to develop an understanding of the nature, pattern and extent of AIDS-related discrimination in several Asian countries. Trained HIV-positive people interviewed 764 positive people in four countries (India 302; Indonesia 42; Thailand 338; the Philippines 82) using a structured questionnaire. Findings indicate that the major area of discrimination in each country is within the health sector, where over half of those surveyed experienced some form of discrimination. In all countries, the majority of people did not receive pre-test counselling before being tested for HIV. People who reported coerced testing were significantly more likely than other respondents to face subsequent AIDS-related discrimination. A considerable number of respondents were refused treatment after being diagnosed with HIV and many experienced delayed provision of treatment or health services. Breaches of confidentiality by health workers were common. Within the family and the community, women were significantly more likely to experience discrimination than men, including ridicule and harassment, physical assault and being forced to change their place of residence because of their HIV status. These findings have serious implications, particularly in light of the increasing trend in many countries to test all pregnant women in order to prevent transmission of HIV to their unborn children.
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Affiliation(s)
- S Paxton
- APN+/Australian Research Centre in Sex, Health & Society, La Trobe University, Australia.
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Riis ALD, Jørgensen JOL, Gjedde S, Nørrelund H, Jurik AG, Nair KS, Ivarsen P, Weeke J, Møller N. Whole body and forearm substrate metabolism in hyperthyroidism: evidence of increased basal muscle protein breakdown. Am J Physiol Endocrinol Metab 2005; 288:E1067-73. [PMID: 15657093 DOI: 10.1152/ajpendo.00253.2004] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Thyroid hormones have significant metabolic effects, and muscle wasting and weakness are prominent clinical features of chronic hyperthyroidism. To assess the underlying mechanisms, we examined seven hyperthyroid women with Graves' disease before (Ht) and after (Eut) medical treatment and seven control subjects (Ctr). All subjects underwent a 3-h study in the postabsorptive state. After regional catheterization, protein dynamics of the whole body and of the forearm muscles were measured by amino acid tracer dilution technique using [15N]phenylalanine and [2H4]tyrosine. Before treatment, triiodothyronine was elevated (6.6 nmol/l) and whole body protein breakdown was increased 40%. The net forearm release of phenylalanine was increased in hyperthyroidism (microg.100 ml(-1).min(-1)): -7.0 +/- 1.2 Ht vs. -3.8 +/- 0.8 Eut (P = 0.04), -4.2 +/- 0.3 Ctr (P = 0.048). Muscle protein breakdown, assessed by phenylalanine rate of appearance, was increased (microg.100 ml(-1).min(-1)): 15.5 +/- 2.0 Ht vs. 9.6 +/- 1.4 Eut (P = 0.03), 9.9 +/- 0.6 Ctr (P = 0.02). Muscle protein synthesis rate did not differ significantly. Muscle mass and muscle function were decreased 10-20% before treatment. All abnormalities were normalized after therapy. In conclusion, our results show that hyperthyroidism is associated with increased muscle amino acid release resulting from increased muscle protein breakdown. These abnormalities can explain the clinical manifestations of sarcopenia and myopathy.
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Abstract
Oesophageal carcinoma remains a disease of poor prognosis. Surgical cure rates are compromised by the fact that most patients are diagnosed at a late stage of disease because of the delayed onset of symptoms, by which time metastases and organ infiltration may have already occurred. Thus, invasion and metastases play a key role in influencing patient survival, and the search for novel treatments may therefore hinge on gaining insight into the mechanisms controlling these processes. It has been established that the initial step in the metastatic cascade is the detachment of tumour cells from the primary tumour via dysregulation of normal cell-cell and cell-matrix interactions. Distinct proteins known as cell adhesion molecules (CAMs) mediate these interactions. In recent years, a plethora of information has contributed to the in depth understanding of these molecules. This review provides a brief description of five families of CAMs (cadherins, integrins, CD44, immunoglobulin superfamily, and selectins) and highlights their altered expression in relation both to prognosis and tumour behaviour in squamous cell carcinoma and adenocarcinoma of the oesophagus.
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Affiliation(s)
- K S Nair
- Pfizer Molecular Biology Research Facility, Doris Duke Medical Research Institute, Nelson R Mandela School of Medicine, University of Natal, Congella 4013, Durban, South Africa
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Abstract
Increasingly, the worldwide population is growing older. Sarcopenia occurs with age and is characterized by loss of muscle mass, strength and endurance. Mechanisms that underlie this process are beginning to be understood. These include age-related loss and atrophy of individual muscle fibers, decreased synthesis of muscle proteins, and reduced mitochondrial function. The role of decreased anabolic hormone production in causing these changes remains to be clearly defined. Anabolic hormone replacement is a potential strategy currently being investigated for treatment of sarcopenia. Combinations of aerobic, resistance, and stretching exercise programs have well established beneficial effects. Further understanding of the molecular processes involved in the aging of muscle both at the level of gene expression and protein modification will be important for discovering novel treatment strategies.
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Affiliation(s)
- L J S Greenlund
- Department of Endocrinology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
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Basu R, Basu A, Nair KS. Muscle changes in aging. J Nutr Health Aging 2002; 6:336-41. [PMID: 12474025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
This review summarizes the recent studies to understand the mechanisms of sarcopenia of aging. A decrease in mitochondrial and nuclear gene transcriptions in skeletal muscle is likely to be responsible for reduced synthesis rates of muscle mitochondrial protein, myosin heavy chain (MHC) and actin. A decrease in muscle mitochondrial protein synthesis could contribute to reduced mitochondrial function. A decrease in synthesis rate of MHC and actin, the key contractile proteins could be responsible for reduced muscle strength. The MHC synthesis rate seems to result from a selective decrease in transcription of MHC isoforms (MHCIIa and IIx) responsible for fast-twitch fibers. Resistance training increases MHC-I isoform mRNA levels with an overall increase in MHC synthesis rate. Aerobic training increases muscle oxidative enzymes equally in young and old but its impact on overall mitochondrial function remains to be clearly defined. Long-term studies are needed to determine the potential benefits and undesirable effects of replacements of various hormones that decline with aging. An individualized exercise prescription involving both aerobic and resistance training is definitely helpful to overcome many aging-related muscle dysfunctions.
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Affiliation(s)
- R Basu
- K. Sreekumaran Nair, MD, PhD, Mayo Clinic Foundation200 1st Street SW, Rm 5-194, Rochester, MN 55905, U.S.A. Phone: 507-255-6515. Fax: 507-255-4828. E-mail:
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Nielsen S, Jørgensen JOL, Hartmund T, Nørrelund H, Nair KS, Christiansen JS, Møller N. Effects of lowering circulating free fatty acid levels on protein metabolism in adult growth hormone deficient patients. Growth Horm IGF Res 2002; 12:425-433. [PMID: 12423628 DOI: 10.1016/s1096-6374(02)00119-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Our study was conducted to define the roles of lowering circulating free fatty acids (FFA) and of growth hormone (GH) replacement on protein metabolism in GH deficient patients. To isolate the specific effects of FFA and GH we studied seven adult subjects with GH deficiency four times: (A) with administration of GH and Acipimox (an inhibitor of lipolysis), (B) with GH, without Acipimox, (C) without GH, with Acipimox and (D) without either. Each study included a 3 h basal period and a 3 h euglycemic clamp. Amino acid metabolism was assessed by stable isotope dilution technique at the whole body level and across the forearm. Overall, we saw no intervention effect on protein metabolism, but when the two situations in which Acipimox was given were combined, Acipimox decreased basal plasma FFA concentrations by 75% and increased serum urea concentrations by 20%, whole body appearance rates (reflecting protein degradation) of phenylalanine (by 7%) and tyrosine (by 11%) and protein synthesis rates for phenylalanine (by 7%), whereas phenylalanine-to-tyrosine conversion was unaffected. Acipimox more than doubled net forearm phenylalanine release during the clamp and increased basal forearm phenylalanine disappearance (reflecting muscle protein synthesis). During the clamp whole body amino acid fluxes and phenylalanine-to-tyrosine conversion decreased together with a decrease in forearm protein breakdown. GH replacement did not affect any of these metabolic parameters. Although we failed to show any role for GH, the results show that lowering of FFA concentrations with Acipimox has pronounced effects on protein metabolism, including increased whole body and forearm protein breakdown, together with increased protein synthesis systemically and locally in the forearm. The increase in serum urea and a doubling of net forearm phenylalanine release after lowering of FFA strongly indicate that the overall effect is catabolic and supports a pivotal protein conserving role of lipids.
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Affiliation(s)
- Steen Nielsen
- Medical Department M, Aarhus University Hospital, Aarhus C, Denmark
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Affiliation(s)
- K S Nair
- Department of Transplant Immunology, Heart Science Centre, Harefield Hospital, Harefield, Middlesex UB9 6JH, UK
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Halvatsiotis PG, Turk D, Alzaid A, Dinneen S, Rizza RA, Nair KS. Insulin effect on leucine kinetics in type 2 diabetes mellitus. Diabetes Nutr Metab 2002; 15:136-42. [PMID: 12173727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Insulin-induced glucose disposal is impaired in Type 2 diabetes mellitus (T2DM). To determine whether insulin-induced suppression of protein breakdown also is impaired, we measured leucine flux (an index of protein breakdown) in diabetic and nondiabetic subjects during a hyperinsulinemic euglycemic clamp. To avoid the confounding effects of a difference in baseline glucose, glucose concentration in the diabetic subjects was normalized by means of an overnight insulin infusion. Despite higher plasma insulin levels (33.5+/-0.05 vs 132+/-2.7 pmol/l, p<01) diabetic subjects had similar amino acid concentrations and leucine flux (96.9+/-5.8 vs 93.4+/-3.7 micromol/kg/h) as nondiabetic subjects. Infusion of insulin (0.5 mU/kg/min) increased insulin levels (p<0.01) to identical levels in both groups (218+/-16 vs 222+/-19), but the glucose infusion required to maintain euglycemia was higher (p<0.01) in nondiabetic than in diabetic subjects, indicating insulin resistance to glucose disposal in the diabetic subjects. In contrast, leucine flux (81.3+/-4.8 vs 81.6+/-3.4 micromol/kg/h) reached identical levels in both groups. The individual and total amino acid levels also were comparable in both groups. We conclude that suppression of whole body protein turnover in response to an acute increase in insulin is normal in people with T2DM. However, chronic adaptation to high insulin levels occurs, thereby enabling protein breakdown and amino acid concentration to remain within the normal range in people with T2DM.
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Affiliation(s)
- P G Halvatsiotis
- Division of Endocrinology, Mayo Clinic and Foundation, Rochester, MN 55905, USA
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Affiliation(s)
- K S Nair
- Cardiothoracic Surgery, Harefield Hospital, Middlesex, UK.
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Morgenstern B, Nair KS, Lerner G, Neu A, Quan A, Warady BA. Impact of total body water errors on Kt/V estimates in children on peritoneal dialysis. Adv Perit Dial 2002; 17:260-3. [PMID: 11510289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Determining Kt/V in peritoneal dialysis (PD) requires estimation of total body water (TBW). The Dialysis Outcomes Quality Initiative (DOQI) guidelines recommend use of the Mellits and Cheek (MC) formulas for the estimation of TBW in children. However, the MC formulas were developed from healthy children and may not apply to children on PD. Re-evaluating the MC data with additional, recent data from healthy infants has led to the development of new formulas. In addition, and as part of a prospective study of children initiating PD, the Pediatric Peritoneal Dialysis Study Consortium (PPDSC) has directly measured TBW using H2[18O]. To assess the impact of various TBW estimates, KPDt/V values prospectively collected in 24 children were calculated using H2[18O]-measured TBW (O18), MC-derived TBW (MCD), and new-formula TBW (NEW). The mean weekly KPDt/V by O18 was 2.2; by MCD, it was 2.0; and by NEW, it was 2.0. The results derived using the O18 method varied from both the MCD and the NEW results (p < 0.001). The mean deviation from the measured KPDt/V using O18 was 9.5% (maximum: 16%) using the MCD estimate and 7.8% (maximum: 18%) using the NEW formulas. Determinations of KPDt/V are significantly affected by the method of estimating TBW. The PPDSC formulas for children on PD based on the use of H2[18O] offer the most accurate means of calculating TBW and should replace formulas derived from healthy children. The use of Kt/V itself as a marker of adequacy in children will be validated only in prospective studies.
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Affiliation(s)
- K S Nair
- Department of Cardiothoracic Surgery, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
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Abstract
In vivo studies have reported conflicting effects of insulin on mixed tissue protein synthesis rates. To test the hypothesis that insulin has differential effects on synthesis rates of various protein fractions in different organs, we infused miniature swine (n = 8 per group) with saline, insulin alone (at 0.7 mU/kg(-1). min(-1)), or insulin plus an amino acid mixture for 8 h. Fractional synthesis rate (FSR) of mitochondrial and cytoplasmic proteins in liver, heart, and skeletal muscle, as well as myosin heavy chain (MHC) in muscle, were measured using L-[1-(13)C]leucine as a tracer. The FSR of mitochondrial and cytoplasmic proteins were highest in liver, followed by heart and then muscle. Mitochondrial FSR in muscle was higher during insulin and insulin plus amino acid infusions than during saline. Insulin had no significant effect on FSR of MHC in muscle. In contrast, FSR of both mitochondrial and cytoplasmic proteins were not stimulated by insulin in liver. Insulin also did not increase FSR of mitochondrial in heart, whereas insulin and amino acid stimulated FSR of cytoplasmic protein. In conclusion, insulin stimulates the synthesis of muscle mitochondrial proteins, with no significant stimulatory effect on synthesis of sarcoplasmic and MHC. These results demonstrate that insulin has different effects on synthesis rates of specific protein fractions in the liver, heart, and skeletal muscle.
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Affiliation(s)
- Y Boirie
- Division of Endocrinology and Metabolism, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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Abstract
Loss of muscle mass, strength, and oxidative capacity accompanies normal aging in humans. The mechanisms responsible for these changes remain to be clearly defined. Muscle protein mass and function depend on protein turnover. Synthesis rate of the major muscle contractile protein, myosin heavy chain (MHC), and transcript levels of fast MHC isoforms decrease in association with strength reductions, while mitochondrial protein synthesis rate declines in parallel with activities of mitochondrial enzymes and maximal oxidative capacity (VO2max). Resistance exercise training increases the synthesis rate of MHC and transcript levels of the slow MHC isoform in older humans, along with increasing muscle strength. The relationship between the synthesis of muscle proteins, and muscle size and function, with aging and exercise training are discussed in this review.
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Affiliation(s)
- K R Short
- Endocrinology Research Unit, Mayo Clinic and Foundation, Rochester, MN 55905, USA
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37
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Abstract
Muscle oxidative function appears to decline with aging, and evidence suggests that this is related to reduced synthesis of mitochondrial and other muscle proteins. Causes for these events may include mtDNA damage or reduced mtDNA copy numbers, reduced oxidative enzyme activities and ATP production, and increased proton leak.
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Affiliation(s)
- K R Short
- Endocrinology Research Unit, Mayo Clinic and Foundation, Rochester, Minnesota, USA
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Nørrelund H, Møller N, Nair KS, Christiansen JS, Jørgensen JO. Continuation of growth hormone (GH) substitution during fasting in GH-deficient patients decreases urea excretion and conserves protein synthesis. J Clin Endocrinol Metab 2001; 86:3120-9. [PMID: 11443176 DOI: 10.1210/jcem.86.7.7618] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The consequences of GH deficiency during conditions in which endogenous GH release is acutely stimulated are largely unknown. Short-term fasting constitutes a robust GH stimulus, but the metabolic significance of GH during fasting is uncertain. To address both of these issues, we therefore evaluated the effect of GH on substrate metabolism during fasting in adults with GH deficiency. Seven hypopituitary GH-deficient patients were each studied twice during a 40-h fast: once with GH replacement continued and once with GH discontinued during the fast. After 40 h of fasting, protein synthesis and turnover were higher with than without GH replacement [phenylalanine incorporation (micromol/kg fat free mass/h): 36.6 +/- 1.2 (GH) vs. 32.8 +/- 1.4, P < 0.05; phenylalanine flux (micromol/kg fat free mass/h): 41.3 +/- 1.0 (GH) vs. 38.0 +/- 1.8, P < 0.05]. During continued GH replacement, urea excretion decreased during nighttime [urea excretion (mmol/24 h): 269 +/- 51 (GH) vs. 390 +/- 69, P < 0.05], and a significant decline in urea-N synthesis rate was found [urea-N synthesis rate (mmol/h): 14.7 +/- 1.6 (GH) vs. 21.1 +/- 2.2, P < 0.01]. GH replacement was associated with increased lipid oxidation [lipid oxidation (mg/kg per min): 0.91 +/- 0.07 (GH) vs. 0.70 +/- 0.03, P < 0.05]. Finally, continuation of GH induced moderate elevations in plasma glucose levels without significant changes in total glucose turnover or oxidation. In summary, continued GH substitution during fasting conserves nitrogen, which involves stimulation or maintenance of protein synthesis. Our data support the importance of GH replacement in hypopituitary adults.
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Affiliation(s)
- H Nørrelund
- Medical Department M (Endocrinology and Diabetes), Aarhus Kommunehospital, Aarhus DK-8000, Denmark.
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39
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Basu A, Basu R, Shah P, Vella A, Johnson CM, Jensen M, Nair KS, Schwenk WF, Rizza RA. Type 2 diabetes impairs splanchnic uptake of glucose but does not alter intestinal glucose absorption during enteral glucose feeding: additional evidence for a defect in hepatic glucokinase activity. Diabetes 2001; 50:1351-62. [PMID: 11375336 DOI: 10.2337/diabetes.50.6.1351] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We have previously reported that splanchnic glucose uptake, hepatic glycogen synthesis, and hepatic glucokinase activity are decreased in people with type 2 diabetes during intravenous glucose infusion. To determine whether these defects are also present during more physiological enteral glucose administration, we studied 11 diabetic and 14 nondiabetic volunteers using a combined organ catheterization-tracer infusion technique. Glucose was infused into the duodenum at a rate of 22 micromol. kg(-1). min(-1) while supplemental glucose was given intravenously to clamp glucose at approximately 10 mmol/l in both groups. Endogenous hormone secretion was inhibited with somatostatin, and insulin was infused to maintain plasma concentrations at approximately 300 pmol/l (i.e., twofold higher than our previous experiments). Total body glucose disappearance, splanchnic, and leg glucose extractions were markedly lower (P < 0.01) in the diabetic subjects than in the nondiabetic subjects. UDP-glucose flux, a measure of glycogen synthesis, was approximately 35% lower (P < 0.02) in the diabetic subjects than in the nondiabetic subjects. This was entirely accounted for by a decrease (P < 0.01) in the contribution of extracellular glucose because the contribution of the indirect pathway to hepatic glycogen synthesis was similar between groups. Neither endogenous and splanchnic glucose productions nor rates of appearance of the intraduodenally infused glucose in the portal vein differed between groups. In summary, both muscle and splanchnic glucose uptake are impaired in type 2 diabetes during enteral glucose administration. The defect in splanchnic glucose uptake appears to be due to decreased uptake of extracellular glucose, implying decreased glucokinase activity. Thus, abnormal hepatic and muscle (but not gut) glucose metabolism are likely to contribute to postprandial hyperglycemia in people with type 2 diabetes.
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Affiliation(s)
- A Basu
- Division of Endocrinology, Metabolism and Nutrition, Mayo Clinic and Foundation, 200 1st St, SW, Rochester, MN 55905, USA
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40
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Abstract
Cystic fibrosis (CF) patients are reported to experience chronic protein catabolism. Since diabetes or impaired glucose tolerance (IGT) is common in CF, we hypothesized that their protein catabolic state is related to reduced insulin secretion or reduced insulin action. A total of 12 clinically stable adult CF patients with abnormal glucose tolerance and 12 age-, sex-, and lean body mass-matched healthy control subjects underwent protein turnover studies using L-[1-(13)C]leucine, L-[(15)N]phenylalanine, and L-[(2)H(4)]tyrosine, with and without exogenous insulin infusion. In the baseline fasting state, protein metabolism was entirely normal in CF patients, with no evidence of increased protein catabolism. In contrast, striking abnormalities were seen in CF patients when insulin was infused, since they did not experience normal suppression of the appearance rates of leucine, phenylalanine, or tyrosine (indexes of protein breakdown). At an insulin concentration of 45 +/- 2 microU/ml, normal control subjects suppressed the leucine appearance rate by 19 +/- 5% (P < 0.01), ketoisocaproate appearance rate by 10 +/- 3% (P = 0.03), tyrosine appearance rate by 11 +/- 2% (P = 0.03), and phenylalanine appearance rate by 6 +/- 3% (P = 0.07). Phenylalanine conversion to tyrosine decreased by 22 +/- 7% (P = 0.03). At a similar insulin concentration of 44 +/- 3 microU/ml, normal suppression of amino acid appearance did not occur in CF. The leucine appearance rate decreased by 4 +/- 2% (P = 0.65), ketoisocaproate appearance rate by 1 +/- 2% (P = 0.94), tyrosine appearance rate by 0 +/- 6% (P = 0.56), phenylalanine appearance rate by 5 +/- 6% (P = 0.34), and phenylalanine conversion to tyrosine by 5 +/- 6% (P = 0.95). Poor suppression of the amino acid appearance rate in CF was not related to previously documented glucose tolerance status (IGT or CF-related diabetes without fasting hyperglycemia), fasting insulin levels, the acute insulin response, insulin sensitivity, cytokine or counterregulatory hormone levels, resting energy expenditure, caloric intake, pulmonary function, or clinical status. Protein synthesis was not significantly affected by insulin infusion in either normal control subjects or CF patients. In conclusion, clinically stable adult CF patients have normal indexes of protein breakdown and synthesis in the fasting state. In contrast, elevation of plasma insulin to physiological postprandial levels fails to normally suppress indexes of protein breakdown. It is therefore likely that inability to spare protein during the postprandial state is the cause of protein catabolism in these patients.
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Affiliation(s)
- A Moran
- Division of Endocrinology, Department of Pediatrics, Box 404, University of Minnesota, 516 Delaware St., Minneapolis, MN 55455, USA.
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41
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Abstract
Muscle protein synthesis was measured by infusion of L-[2H(5)]phenylalanine in two groups of anesthetized dogs, before and during infusion of insulin with euaminoacidemia, and with differing concentrations of unlabeled phenylalanine (tracee). With the infusion of insulin, muscle protein synthesis increased 39 +/- 12% based on phenylalanyl-tRNA. Calculation with plasma phenylalanine enrichment overestimated insulin stimulation by 40% (56 +/- 12 vs. 39 +/- 12%). Raising the concentration of plasma phenylalanine twofold during infusion of insulin further increased the apparent stimulation of muscle protein synthesis based on plasma relative to phenylalanyl-tRNA by 225% (65 +/- 19 vs. 20 +/- 14%, P < 0.001). In both experiments, the stimulation of synthesis rates calculated from phenylalanine enrichment within the muscle was closer to that from phenylalanyl-tRNA (48 +/- 19%, experiment 1; 30 +/- 14%, experiment 2). Results indicate that the enrichment of a labeled amino acid within plasma and tissue amino acid pools is affected by the concentration of tracee infused. Increasing the concentration of tracee overestimates the insulin-mediated stimulation of muscle protein synthesis when amino acid pools other than aminoacyl-tRNA are used as the precursor enrichment.
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Affiliation(s)
- G Caso
- Department of Surgery, State University of New York, Stony Brook, New York 11794, USA
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42
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Short KR, Nygren J, Barazzoni R, Levine J, Nair KS. T(3) increases mitochondrial ATP production in oxidative muscle despite increased expression of UCP2 and -3. Am J Physiol Endocrinol Metab 2001; 280:E761-9. [PMID: 11287359 DOI: 10.1152/ajpendo.2001.280.5.e761] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Triiodothyronine (T(3)) increases O(2) and nutrient flux through mitochondria (Mito) of many tissues, but it is unclear whether ATP synthesis is increased, particularly in different types of skeletal muscle, because variable changes in uncoupling proteins (UCP) and enzymes have been reported. Thus Mito ATP production was measured in oxidative and glycolytic muscles, as well as in liver and heart, in rats administered T(3) for 14 days. Relative to saline-treated controls, T(3) rats had 80, 168, and 62% higher ATP production in soleus muscle, liver, and heart, respectively, as well as higher activities of citrate synthase (CS; 63, 90, 25%) and cytochrome c oxidase (COX; 119, 225, 52%) in the same tissues (all P < 0.01). In plantaris muscle of T(3) rats, CS was only slightly higher (17%, P < 0.05) than in controls, and ATP production and COX were unaffected. mRNA levels of COX I and III were 33 and 47% higher in soleus of T(3) rats (P < 0.01), but there were no differences in plantaris. In contrast, UCP2 and -3 mRNAs were 2.5- to 14-fold higher, and protein levels were 3- to 10-fold higher in both plantaris and soleus of the T(3) group. We conclude that T(3) increases oxidative enzymes and Mito ATP production and Mito-encoded transcripts in oxidative but not glycolytic rodent tissues. Despite large increases in UCP expression, ATP production was enhanced in oxidative tissues and maintained in glycolytic muscle of hyperthyroid rats.
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Affiliation(s)
- K R Short
- Endocrinology Research Unit, Mayo Clinic, Rochester, Minnesota 55905, USA
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43
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Ahlman B, Charlton M, Fu A, Berg C, O'Brien P, Nair KS. Insulin's effect on synthesis rates of liver proteins. A swine model comparing various precursors of protein synthesis. Diabetes 2001; 50:947-54. [PMID: 11334437 DOI: 10.2337/diabetes.50.5.947] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Insulin's effect on the synthesis of liver proteins remains to be fully defined. Previous studies using various surrogate measures of amino acyl-tRNA have reported variable results of insulin's effect on liver protein synthesis. We determined the effect of insulin with or without amino acid supplementation on the synthesis rates of liver proteins (tissue, albumin, and fibrinogen) using L-[1-13C]Leu as a tracer in 24 male miniature swine. In addition, we compared the isotopic enrichment of different precursors of liver proteins with that of amino acyl-tRNA using L-[1-13C]Leu and L-[15N]Phe as tracers. Although liver tissue fluid enrichment of [13C]Leu and [15N]Phe and that of plasma [13C]ketoisocaproatic acid (KIC) were very similar to that of tRNA, plasma isotopic enrichment of both Leu and Phe were substantially higher (P < 0.01) and VLDL apolipoprotein-B100 enrichment was lower (P < 0.01) than the respective amino acyl-tRNA enrichment. Plasma KIC enrichment most accurately predicted leucyl-tRNA enrichment, whereas plasma Leu enrichment was best correlated with that of tRNA. Neither insulin alone nor insulin plus amino acid infusion had an effect on liver tissue protein synthesis. In contrast, insulin alone decreased the albumin synthesis rate, and insulin with amino acids maintained the albumin synthesis rate. Insulin with or without amino acids inhibited the fibrinogen synthesis rate. These results, based on synthetic rates using amino acyl-tRNA, were consistent with those obtained using KIC or tissue fluid Leu or Phe as precursor pools. These studies demonstrated that plasma KIC enrichment is a convenient and reliable surrogate measure of leucyl-tRNA in liver. We also concluded that insulin has differential effects on the synthesis rates of liver proteins. Whereas insulin with or without amino acid supplement has no acute effect on the synthesis of liver tissue protein, insulin has a substantial inhibitory effect on fibrinogen synthesis. In contrast, insulin administration along with amino supplement is necessary to maintain albumin synthesis rate.
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Affiliation(s)
- B Ahlman
- Endocrine Research Unit, Division of Endocrinology and Metabolism, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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44
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Abstract
Sarcopenia is a term utilized to define the loss of muscle mass and strength that occurs with aging. Sarcopenia is believed to play a major role in the pathogenesis of frailty and functional impairment that occurs with old age. Progressive muscle wasting occurs with aging. The prevalence of clinically significant sarcopenia is estimated to range from 8.8% in young old women to 17.5% in old old men. Persons who are obese and sarcopenic (the "fat frail") have worse outcomes than those who are sarcopenic and non-obese. There is a disproportionate atrophy of type IIa muscle fibers with aging. There is also evidence of an age-related decrease in the synthesis rate of myosin heavy chain proteins, the major anabolic protein. Motor units innervating muscle decline with aging, and there is increased irregularity of muscle unit firing. There are indications that cytokines-especially interleukin-1beta, tumor necrosis factor-alpha, and interleukin-6-play a role in the pathogenesis of sarcopenia. Similarly, the decline in anabolic hormones-namely, testosterone, dehydroepiandrosterone growth hormone, and insulin-like growth factor-I-is also implicated in the sarcopenic process. The role of the physiologic anorexia of aging remains to be determined. Decreased physical activity with aging appears to be the key factor involved in producing sarcopenia. An increased research emphasis on the factors involved in the pathogenesis of sarcopenia is needed.
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Affiliation(s)
- J E Morley
- Division of Geriatric Medicine, Saint Louis University School of Medicine, MO 63104, USA
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45
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Abstract
The contribution of the kidneys to postabsorptive endogenous glucose production is a matter of controversy. To assess whether this could relate to the use of various isotopical methods with different analytical performance capabilities, we measured glucose kinetics in 12 healthy subjects. Blood samples were taken from the femoral artery and the renal vein after 4 h of [6,6-2H2]glucose infusion (for gas chromatography [GC]/mass spectrometry [MS] analysis), and renal plasma flow was determined with paraaminohippurate. In addition, six subjects received uniformly labeled [13C]glucose (for GC/combustion/isotope ratio MS [IRMS]) and [3-3H]glucose (for counting of radioactive disintegrations). Arterial glucose concentrations (means +/- SD) were 4.2+/-0.1 mmol/l, and endogenous glucose production rates using [2H2]glucose were 2.2+/-0.1 mg x kg(-1) x min(-1) or 818+/-50 micromol/min. Dilution of [2H2]glucose across the kidney was 0.79+/-1.32%, and renal glucose production (RGP) rates were 27+/-72 micromol/min. In the six subjects receiving additional tracers, dilutions across the kidney were 2.83+/-0.72 and 0.54+/-1.20 (for [U-13C]glucose and [3-3H]glucose, respectively, the dilution with [U-13C] being higher than that with [2H2] (P = 0.007). Corresponding RGP values were 144+/-39 and 43+/-76 micromol/min for [U-13C] and [3-3H], respectively. In conclusion, we found that the highly sensitive [U-13C] GC/Combustion/IRMS technique showed consistent dilution of label across the kidney, whereas the less sensitive techniques gave some negative values and smaller RGP rates. Thus, depending on which technique is being used, a fivefold difference in calculated RGP values may be encountered. The methodological variability of our data suggests that extrapolation from regional renal measurements to the whole-body level should be perfumed with caution.
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Affiliation(s)
- N Moller
- Endocrinology Division, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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46
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Abstract
Adhesion of neutrophils to substrate is initiated by receptor-ligand interactions that induce outside-in signaling. Inside-out signals and lateral interactions between surface molecules further fine tune the response. This study investigates the role of CD66 in adhesion of neutrophils to fibronectin, using domain-mapped monoclonal antibodies to CD66. Neutrophils express CD66a, CD66b, and CD66c on their surface. The neutrophil surface molecules that bind to fibronectin are the alpha(4)beta(1) and alpha(5)beta(1) integrins. Our results show that the monoclonal antibody Kat4c, which recognizes the AB domain of CD66a, b, and c and the polyclonal anti-CD66 (anti-carcinoembryonic antigen), augments neutrophil adhesion to fibronectin, while monoclonal antibodies to the individual CD66 antigens, the Fab fragment of Kat4c, and a mixture of the individual antibodies to CD66 antigens were unable to affect the adhesion. Thus heterodimerization of CD66a, b, and c is required for promoting neutrophil adhesion to fibronectin. The increased adhesion in presence of Kat4c was inhibited by antibodies to the beta(1) and beta(2) integrins. Antibody ligation of CD66 antigens causes their clustering and concomitant coclustering of the alpha(M) subunit of the beta(2) integrin, thereby activating the integrin. The sugar alpha-methyl mannoside inhibited anti-CD66-mediated clustering, indicating that a carbohydrate-lectin interaction may exist between CD66 and alpha(M) integrin. It also reduced the increased adhesion of neutrophils to fibronectin, suggesting that beta(2) integrin activation precedes beta(1) integrin activation. Further, the anti-CD66-mediated adhesion to fibronectin is accompanied by increased localization of Src family kinases (lyn and hck) to the cytoskeleton and an increase in their kinase activity. These results suggest that crosslinking of CD66a, CD66b, and CD66c promotes activation of the beta(2) integrin and in turn an alteration in the affinity of the beta(1) integrin, which enhances the adhesion of neutrophils to fibronectin.
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Affiliation(s)
- K S Nair
- Biochemistry and Molecular Biology Division, Cancer Research Institute, Parel, Mumbai, 400 012, India
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47
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Abstract
Uncoupling protein (UCP)-2 and -3 mediate mitochondrial (mt) proton leak in vitro and are potential regulators of energy expenditure and ATP production. Aging is associated with alteration of tissue functions, suggesting impaired mtATP production. To determine whether age-related changes in UCP expression occur, we measured the transcript levels of UCP-2 and -3 in skeletal muscle, liver, and heart in 6- and 27-mo-old rats. UCP-2 transcripts were higher in old animals in the white (+100%) and red (+70%, both P < 0.04) gastrocnemius muscle and in the liver (+300%, P < 0.03), whereas they were comparable in the heart in both age groups. UCP-2 transcript levels correlated positively with mitochondrial-encoded cytochrome c oxidase transcripts normalized for mtDNA (P < 0.01) and negatively with mtDNA copy number (P < 0.001). UCP-3 transcripts were lower in the less oxidative white (-50%, P < 0.04) and unchanged in the more oxidative red (-15%, P = 0.41) gastrocnemius muscle in old animals. Similar changes at protein level were confirmed by UCP-2 protein in aging liver (+300%, P < 0.01) and UCP-2 (+85%, P < 0.05) and UCP-3 (-30%, P = 0.4) protein in aging mixed gastrocnemius muscle. Aging is thus associated with tissue-specific changes of UCP-2 and -3 gene expression. Increased UCP-2 expression may limit ATP production and is related to mitochondrial gene expression in aging muscles and liver. Different age-related changes may reflect differential regulation of UCP-2 and -3 in skeletal muscle. The current data suggest a potential role of uncoupling proteins to alter energy production in aging tissues.
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Affiliation(s)
- R Barazzoni
- Endocrine Research Unit, Mayo Clinic and Foundation, Joseph 5-194, Rochester, MN 55905, USA
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48
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Abstract
Experimental evidence indicates that a lower synthesis rate of muscle contractile protein myosin heavy chain (MHC) occurs in age-related muscle wasting and weakness. To determine the molecular mechanism of this lower synthesis of MHC, we measured transcript levels of isoforms of MHC (MHCI, MHCIIa, and MHCIIx) in muscle biopsy samples of 7 young (20-27 yr), 12 middle-aged (47-60 yr), and 14 older (>65 yr) people. We further determined the effect of 3 mo of resistance exercise training (exercise) vs. nonintervention (control) on transcript levels of MHC isoforms on these subjects and the fractional synthesis rate (FSR) of MHC in 39 people aged 46-79 yr. MHCI mRNA levels did not significantly change with age, but MHCIIa decreased 38% (P < 0.05) from young to middle age and further decreased 50% (P < 0.05) from middle to old age. MHCIIx decreased 84% (P < 0.05) from young to middle age and 48% from middle to old age (P < 0.05). Exercise increased FSR of MHC by 47% (P < 0.01) and mixed muscle protein by 56% (P < 0.05). Exercise training results in an increase (85%) in transcript levels of MHCI and a decrease in the transcript levels of MHCIIa and MHCIIx. In conclusion, an age-related lowering of the transcript levels of MHCIIa and MHCIIx is not reversed by exercise, whereas exercise results in a higher synthesis rate of MHC in association with an increase in MHCI isoform transcript levels.
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Affiliation(s)
- P Balagopal
- Endocrinology Division, Mayo Clinic, 200 First St., Rochester, Minnesota 55905, USA
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49
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Nørrelund H, Nair KS, Jørgensen JO, Christiansen JS, Møller N. The protein-retaining effects of growth hormone during fasting involve inhibition of muscle-protein breakdown. Diabetes 2001; 50:96-104. [PMID: 11147801 DOI: 10.2337/diabetes.50.1.96] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The metabolic response to fasting involves a series of hormonal and metabolic adaptations leading to protein conservation. An increase in the serum level of growth hormone (GH) during fasting has been well substantiated. The present study was designed to test the hypothesis that GH may be a principal mediator of protein conservation during fasting and to assess the underlying mechanisms. Eight normal subjects were examined on four occasions: 1) in the basal postabsorptive state (basal), 2) after 40 h of fasting (fast), 3) after 40 h of fasting with somatostatin suppression of GH (fast-GH), and 4) after 40 h of fasting with suppression of GH and exogenous GH replacement (fast+GH). The two somatostatin experiments were identical in terms of hormone replacement (except for GH), meaning that somatostatin, insulin, glucagon and GH were administered for 28 h; during the last 4 h, substrate metabolism was investigated. Compared with the GH administration protocol, IGF-I and free IGF-I decreased 35 and 70%, respectively, during fasting without GH. Urinary urea excretion and serum urea increased when participants fasted without GH (urea excretion: basal 392 +/- 44, fast 440 +/- 32, fast-GH 609 +/- 76, and fast+GH 408 +/- 36 mmol/24 h, P < 0.05; serum urea: basal 4.6 +/- 0.1, fast 6.2 +/- 0.1, fast-GH 7.0 +/- 0.2, and fast+GH 4.3 +/- 0.2 mmol/1, P < 0.01). There was a net release of phenylalanine across the forearm, and the negative phenylalanine balance was higher during fasting with GH suppression (balance: basal 9 +/- 3, fast 15 +/- 6, fast-GH 17 +/- 4, and fast+GH 11 +/- 5 nmol/min, P < 0.05). Muscle-protein breakdown was increased among participants who fasted without GH (phenylalanine rate of appearance: basal 17 +/- 4, fast 26 +/- 9, fast-GH 33 +/- 7, fast+GH 25 +/- 6 nmol/min, P < 0.05). Levels of free fatty acids and oxidation of lipid decreased during fasting without GH (P < 0.01). In summary, we find that suppression of GH during fasting leads to a 50% increase in urea-nitrogen excretion, together with an increased net release and appearance rate of phenylalanine across the forearm. These results demonstrate that GH-possibly by maintenance of circulating concentrations of free IGF-I--is a decisive component of protein conservation during fasting and provide evidence that the underlying mechanism involves a decrease in muscle protein breakdown.
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Affiliation(s)
- H Nørrelund
- Medical Department M, Aarhus Kommunehospital, Denmark.
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50
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Lee JS, Camilleri M, Zinsmeister AR, Burton DD, Choi MG, Nair KS, Verlinden M. Toward office-based measurement of gastric emptying in symptomatic diabetics using [13C]octanoic acid breath test. Am J Gastroenterol 2000; 95:2751-61. [PMID: 11051344 DOI: 10.1111/j.1572-0241.2000.03183.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Current methods for measuring gastric emptying by breath test require sampling over several hours and are too inaccurate for clinical use. The aim of this study was to develop an office-based method for measuring gastric emptying of solids in patients with diabetes using a [13C]octanoic acid breath test. METHODS In 22 symptomatic diabetic patients (17 insulin-dependent diabetes, 5 non-insulin-dependent diabetes) and 6 controls, we simultaneously measured gastric emptying of an egg meal (420 kcal) by scintigraphy and [13C]octanoic acid breath test. Conventional (nonlinear) methods for scintigraphic and [13C]octanoic acid breath test emptying and generalized linear regression method to predict scintigraphic half-life (t(1/2)) using four breath samples obtained during the first 3 h. RESULTS Despite 8 h of breath sampling, the t(1/2) estimate using the conventional method was markedly different from the scintigraphic value (delta t(1/2): median, 113 min; range, 19-282 min). The generalized linear model (using samples at baseline, 30, and 120 or 150 min) yielded predicted scintigraphic tLAG and t(1/2) that were more accurate than the conventional method; mean standard deviations of differences were 16 and 27 min, respectively. Breath test correctly assessed normal or prolonged emptying in 21 of 22 patients. CONCLUSIONS The [13C]octanoic acid breath test can be simplified to measure gastric tLAG and t(1/2) and can be expected to correctly identify normal t(1/2) in symptomatic diabetics. Further refinement of the model will need to include studies of patients with markedly delayed t(1/2).
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Affiliation(s)
- J S Lee
- Gastroenterology Research Unit, Section of Biostatistics, Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905, USA
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