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Singh P, Gollapalli K, Mangiola S, Schranner D, Yusuf MA, Chamoli M, Shi SL, Bastos BL, Nair T, Riermeier A, Vayndorf EM, Wu JZ, Nilakhe A, Nguyen CQ, Muir M, Kiflezghi MG, Foulger A, Junker A, Devine J, Sharan K, Chinta SJ, Rajput S, Rane A, Baumert P, Schönfelder M, Iavarone F, Lorenzo GD, Kumari S, Gupta A, Sarkar R, Khyriem C, Chawla AS, Sharma A, Sarper N, Chattopadhyay N, Biswal BK, Settembre C, Nagarajan P, Targoff KL, Picard M, Gupta S, Velagapudi V, Papenfuss AT, Kaya A, Ferreira MG, Kennedy BK, Andersen JK, Lithgow GJ, Ali AM, Mukhopadhyay A, Palotie A, Kastenmüller G, Kaeberlein M, Wackerhage H, Pal B, Yadav VK. Taurine deficiency as a driver of aging. Science 2023; 380:eabn9257. [PMID: 37289866 PMCID: PMC10630957 DOI: 10.1126/science.abn9257] [Citation(s) in RCA: 45] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Accepted: 04/14/2023] [Indexed: 06/10/2023]
Abstract
Aging is associated with changes in circulating levels of various molecules, some of which remain undefined. We find that concentrations of circulating taurine decline with aging in mice, monkeys, and humans. A reversal of this decline through taurine supplementation increased the health span (the period of healthy living) and life span in mice and health span in monkeys. Mechanistically, taurine reduced cellular senescence, protected against telomerase deficiency, suppressed mitochondrial dysfunction, decreased DNA damage, and attenuated inflammaging. In humans, lower taurine concentrations correlated with several age-related diseases and taurine concentrations increased after acute endurance exercise. Thus, taurine deficiency may be a driver of aging because its reversal increases health span in worms, rodents, and primates and life span in worms and rodents. Clinical trials in humans seem warranted to test whether taurine deficiency might drive aging in humans.
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Affiliation(s)
- Parminder Singh
- Metabolic Research Laboratories, National Institute of Immunology; New Delhi, India
| | - Kishore Gollapalli
- Vagelos College of Physicians and Surgeons, Columbia University; New York, USA
| | - Stefano Mangiola
- Department of Medical Biology, University of Melbourne; Melbourne, Australia
- School of Cancer Medicine, La Trobe University; Bundoora, Australia
- Olivia Newton-John Cancer Research Institute; Heidelberg, Australia
| | - Daniela Schranner
- Exercise Biology Group, Technical University of Munich; Munich, Germany
- Institute of Computational Biology, Helmholtz Zentrum München; Neuherberg, Germany
| | - Mohd Aslam Yusuf
- Department of Bioengineering, Integral University; Lucknow, India
| | - Manish Chamoli
- Buck Institute of Age Research, 8001 Redwood Blvd; California, USA
| | - Sting L. Shi
- Vagelos College of Physicians and Surgeons, Columbia University; New York, USA
| | - Bruno Lopes Bastos
- Institute for Research on Cancer and Aging of Nice (IRCAN); Nice, France
| | - Tripti Nair
- Molecular Aging Laboratory, National Institute of Immunology; New Delhi, India
| | - Annett Riermeier
- Exercise Biology Group, Technical University of Munich; Munich, Germany
| | - Elena M. Vayndorf
- Department of Laboratory Medicine and Pathology, University of Washington; WA, USA
| | - Judy Z. Wu
- Department of Laboratory Medicine and Pathology, University of Washington; WA, USA
| | - Aishwarya Nilakhe
- Metabolic Research Laboratories, National Institute of Immunology; New Delhi, India
| | - Christina Q. Nguyen
- Department of Laboratory Medicine and Pathology, University of Washington; WA, USA
| | - Michael Muir
- Department of Laboratory Medicine and Pathology, University of Washington; WA, USA
| | - Michael G. Kiflezghi
- Department of Laboratory Medicine and Pathology, University of Washington; WA, USA
| | - Anna Foulger
- Buck Institute of Age Research, 8001 Redwood Blvd; California, USA
| | - Alex Junker
- Department of Neurology, Columbia University; New York, USA
| | - Jack Devine
- Department of Neurology, Columbia University; New York, USA
| | - Kunal Sharan
- Mouse Genetics Project, Wellcome Sanger Institute; Cambridge, UK
| | | | - Swati Rajput
- Division of Endocrinology, CSIR-Central Drug Research Institute; Lucknow, India
| | - Anand Rane
- Buck Institute of Age Research, 8001 Redwood Blvd; California, USA
| | - Philipp Baumert
- Exercise Biology Group, Technical University of Munich; Munich, Germany
| | | | | | | | - Swati Kumari
- Metabolic Research Laboratories, National Institute of Immunology; New Delhi, India
| | - Alka Gupta
- Metabolic Research Laboratories, National Institute of Immunology; New Delhi, India
| | - Rajesh Sarkar
- Metabolic Research Laboratories, National Institute of Immunology; New Delhi, India
| | - Costerwell Khyriem
- Harry Perkins Institute of Medical Research; Perth, Australia
- Curtin Medical School, Curtin University; Perth, Australia
| | - Amanpreet S. Chawla
- Immunobiology Laboratory, National Institute of Immunology; New Delhi, India
- MRC-Protein Phosphorylation and Ubiquitination Unit, University of Dundee; Dundee, UK
| | - Ankur Sharma
- Harry Perkins Institute of Medical Research; Perth, Australia
- Curtin Medical School, Curtin University; Perth, Australia
| | - Nazan Sarper
- Pediatrics and Pediatric Hematology, Kocaeli University Hospital; Kocaeli, Turkey
| | | | - Bichitra K. Biswal
- Metabolic Research Laboratories, National Institute of Immunology; New Delhi, India
| | - Carmine Settembre
- Telethon Institute of Genetics and Medicine (TIGEM); Pozzuoli, Italy
- Department of Clinical Medicine and Surgery, Federico II University; Naples, Italy
| | - Perumal Nagarajan
- Primate Research Facility, National Institute of Immunology; New Delhi, India
- Small Animal Research Facility, National Institute of Immunology; New Delhi, India
| | - Kimara L. Targoff
- Division of Cardiology, Department of Pediatrics, Columbia University; New York, USA
| | - Martin Picard
- Department of Neurology, Columbia University; New York, USA
| | - Sarika Gupta
- Metabolic Research Laboratories, National Institute of Immunology; New Delhi, India
| | - Vidya Velagapudi
- Institute for Molecular Medicine Finland FIMM, University of Helsinki; Helsinki, Finland
| | | | - Alaattin Kaya
- Department of Biology, Virginia Commonwealth University; Virginia, USA
| | | | - Brian K. Kennedy
- Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore; Singapore, Singapore
- Centre for Healthy Longevity, National University Health System; Singapore, Singapore
- Departments of Biochemistry and Physiology, Yong Loo Lin School of Medicine, National University of Singapore; Singapore, Singapore
| | | | | | - Abdullah Mahmood Ali
- Department of Medicine, Columbia University Irving Medical Center; New York, USA
| | - Arnab Mukhopadhyay
- Molecular Aging Laboratory, National Institute of Immunology; New Delhi, India
| | - Aarno Palotie
- Institute for Molecular Medicine Finland FIMM, University of Helsinki; Helsinki, Finland
- Broad Institute of Harvard and MIT; Cambridge, USA
- Analytic and Translational Genetics Unit, Massachusetts General Hospital; Boston, USA
| | - Gabi Kastenmüller
- Institute of Computational Biology, Helmholtz Zentrum München; Neuherberg, Germany
| | - Matt Kaeberlein
- Department of Laboratory Medicine and Pathology, University of Washington; WA, USA
| | | | - Bhupinder Pal
- Department of Medical Biology, University of Melbourne; Melbourne, Australia
- School of Cancer Medicine, La Trobe University; Bundoora, Australia
| | - Vijay K. Yadav
- Metabolic Research Laboratories, National Institute of Immunology; New Delhi, India
- Vagelos College of Physicians and Surgeons, Columbia University; New York, USA
- Mouse Genetics Project, Wellcome Sanger Institute; Cambridge, UK
- Department of Genetics and Development, Columbia University; New York, USA
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Chawla AS, Tao C, Faulkner EC, Hsiao CW, Patkar AD, Romney M. Health Economic Impact of Bariatric Surgery Revisted: Structured Review of Literature and Health Technology Assessments. Value Health 2014; 17:A338. [PMID: 27200613 DOI: 10.1016/j.jval.2014.08.659] [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] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
| | - C Tao
- Quintiles Consulting, Cambridge, MA, USA
| | - E C Faulkner
- Institute for Pharmacogenomics and Individualized Therapy, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC, USA
| | - C W Hsiao
- Johnson and Johnson Medical Companies, Markham, ON, Canada
| | | | - M Romney
- Jefferson School of Population Health, Philadelphia, PA, USA
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Chawla AS, Tao C, Spinner DS, Faulkner EC, Doyle JJ. Market Access of Implantable Medical Devices - Part Ii: Decision Drivers Across Global Markets. Value Health 2014; 17:A388. [PMID: 27200887 DOI: 10.1016/j.jval.2014.08.2655] [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] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
| | - C Tao
- Quintiles Consulting, Cambridge, MA, USA
| | | | - E C Faulkner
- Institute for Pharmacogenomics and Individualized Therapy, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC, USA
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Faulkner EC, Spinner DS, Ransom JF, Paul A, Chawla AS, Doyle JJ, Shaw WH, Fitzgerald JT. Next Generation Sequencing Technology: Health Technology Assessment, Market Access Trends and Potential Impacts on The Future of Companion Diagnostic Testing. Value Health 2014; 17:A652. [PMID: 27202356 DOI: 10.1016/j.jval.2014.08.2374] [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] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
- E C Faulkner
- Institute for Pharmacogenomics and Individualized Therapy, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC, USA
| | | | - J F Ransom
- Quintiles Global Consulting, Hawthorne, NY, USA
| | - A Paul
- Quintiles Global Consulting, Durham, NC, USA
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Karov J, Chawla AS, Hinberg I. Effect of reuse on surface characteristics of balloon angioplasty catheters. Artif Cells Blood Substit Immobil Biotechnol 2000; 28:229-40. [PMID: 10852674 DOI: 10.3109/10731190009119354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Surfaces of reused angioplasty catheter balloons were characterized by scanning electron microscopy (SEM), image analysis, Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The surfaces were found to have longitudinal ridges, cracks, wrinkled regions and particulates. Most of the particles were carbon-based, and contained traces of Cl and Si. The average number of particles ranged between 11 and 38 per mm2, while the average particle size ranged from 14 micron to 28 micron. About 70%-90% of the particles were larger then 10 micron which is approximately the diameter of the fine blood capillaries. The particles appeared to be firmly attached to the outer surface of the balloon. FT-IR and XPS analysis revealed the presence of Si, the absence of proteins, and suggested that the surface of the reused balloon catheters was oxidized. The study highlights the large number of particles created and released during angioplasty.
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Affiliation(s)
- J Karov
- Medical Devices Bureau, TPP, Health Canada, Ottawa, Ontario
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Wander GS, Sandha GS, Chawla AS, Khurana SB. Multivalvular thickening in a case of Hunter's syndrome. J Assoc Physicians India 1994; 42:161-2. [PMID: 7860484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- G S Wander
- Dept. of Medicine, dayanand medical college, Ludhiana
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Garg R, Sood A, Arora S, Bhatia KL, Chawla AS, Gupta R, Chawla LS. Ascitic fluid cholesterol in differential diagnosis of ascites. J Assoc Physicians India 1993; 41:644-6. [PMID: 8294324] [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: 01/29/2023]
Abstract
Cholesterol was estimated in ascitic fluid of 89 patients (29 malignant and 60 non-malignant ascites). Mean ascitic cholesterol level was significantly higher in malignant ascites (89.52 mg/dl) as compared to non-malignant ascites (29.93 mg/dl). At a cut off value of 48 mg/dl, the sensitivity, specificity, positive and negative predictive value and overall diagnostic accuracy for diagnosing malignant ascites is 96.5%, 96.6%, 93.3%, 98.3% and 96.6% respectively. Ascitic fluid cholesterol estimation is an easy and reliable test for differentiating malignant ascites from non-malignant ascites.
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Affiliation(s)
- R Garg
- Department of Medicine, Dayanand Medical College and Hospital, Ludhiana
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Abstract
Samples of polyurethane (PU) foam from the Même breast implant were incubated at 37 degrees C in either 0.3-3.0 N sodium hydroxide (NaOH) solutions, normal saline, or methanol. The chemicals released were analyzed by gas chromatography (GC), gas chromatography/mass spectrometry (GC/MS), and Fourier-transform infra-red (FT-IR) spectroscopy. The surfaces of the treated and untreated foam samples were studied by scanning electron microscopy (SEM). The NaOH solutions hydrolysed the foam, releasing toluene diamine (TDA). Incubating the foam in methanol washed out trace quantities of anti-oxidant, 2,4-dimethyl-6-t-butylphenol (DBP). When the foam was incubated in normal saline at 37 degrees C no TDA was detectable but another compound with a mass ion of 173 was detected. Further GC/MS studies confirmed that this compound was polyol, one of the reagents used to manufacture the PU foam. Repeatedly incubating or washing the foam in normal saline or methanol eliminated the release of polyol. SEM studies of the foam samples before and after incubation experiments, showed no evidence of polymer degradation. These findings indicated that polyol was present in the PU foam only as an impurity or residue and did not originate from the breakdown of the foam itself.
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Affiliation(s)
- J N Daka
- Bureau of Radiation & Medical Devices, Health & Welfare Canada, Ottawa, Ontario
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Abstract
In vitro enzymatic degradation of non-porous films of segmented poly(ether urethane) (Pellethane 2363-80AE) was investigated by incubating the biomaterial in concentrated trypsin solutions for 5 months at room temperature. Chemical degradation of films was monitored by surface analysis techniques such as Fourier transform infrared spectroscopy-attenuated total reflectance and electron spectroscopy for chemical analysis. This latter technique proved to be much superior in detecting chemical changes. Extraction of films with methanol and characterization of the extracts by gel permeation chromatography revealed the presence of low-molecular-weight polymers. Results have shown that trypsin has the ability to induce degradation in PEU, the soft segment being most affected, particularly the CH2-O bond of the ether linkages.
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Affiliation(s)
- M Bouvier
- Bureau of Radiation and Medical Devices, Health and Welfare Canada, Ottawa, Ontario
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Chawla AS, Hinberg I. Leaching of plasticizers from and surface characterization of PVC blood platelet bags. Biomater Artif Cells Immobilization Biotechnol 1991; 19:761-83. [PMID: 1810409 DOI: 10.3109/10731199109117853] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The leaching of phthalate plasticizers from four types of blood platelet bags was investigated. The anticoagulant solutions used in the blood collection bags had pH values of 5.64 +/- .04 and contained no detectable amounts of phthalates. Platelet bag materials from each bag were soaked in normal salines for up to 5 days. The salines were tested for the leached phthalates from the bags but none could be found. However, di-(2-ethylhexyl) phthalate (DEHP) leached out of the PL-146 and Terumo bags into bovine calf serum used for soaking the bag materials. There was an increase in the amount of DEHP leached from about 1.1 mg at the end of one day to about 3.3 mg per gm of bag material at the end of a five day extraction with the serum. In PL-732 sets, a platelet bag made of a specialty polyolefin, the amount of DEHP leached out was less than 0.02 mg per g of bag material. CLX bags, which contained tri-(2-ethylhexyl) trimelliate (TETM) as a plasticizer, showed a negligible amount of it leaching into the calf serum. Infra-red spectra showed that PL-146 bags had been coated with a layer of a fatty acid amide while the Terumo bags contained a layer of a silicone fluid on their inner surfaces. CLX bags showed a coating of stearates, which were probably soaps of calcium or zinc. Scanning electron microscopy (SEM) showed that the inner surfaces of each brand of the bag were distinctly different morphologically. The two PVC bags were very similar whereas the surfaces morphology of PL-732 was rougher. Terumo bag had a different surface morphology than those of the other bags whereas the CLX bags had a very regular surface pattern. The exact significance of the surface morphology is not certain but excessively rough surfaces may not be desirable for the bags.
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Affiliation(s)
- A S Chawla
- Bureau of Radiation and Medical Devices, Health and Welfare Canada, Ottawa, Ontario
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Affiliation(s)
- A S Chawla
- Department of Pharmaceutical Sciences, Panjab University, Chandigarh, India
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Affiliation(s)
- A S Chawla
- Department of Pharmaceutical Sciences, Panjab University, Chandigarh, India
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Sipehia R, Chawla AS, Daka J, Chang TM. Immobilization of enzymes on polypropylene bead surfaces by anhydrous ammonia gaseous plasma technique. J Biomed Mater Res 1988; 22:417-22. [PMID: 3397380 DOI: 10.1002/jbm.820220505] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Anhydrous ammonia gaseous plasma technique was used for the surface modification of polypropylene beads. Amino groups were added onto the surfaces of beads by exposing them to ammonia plasma. Through these amino groups covalent immobilization of glucose oxidase and peroxidase were carried out. The total amounts of immobilized glucose oxidase and immobilized peroxidase were found to be 52 and 43 micrograms/cm2, respectively. To assess the stability of enzyme-polypropylene linkage, beads with covalently immobilized glucose oxidase and peroxidase were washed with phosphate buffer. It was found that after the removal of the adsorbed enzymes, the concentration of covalently immobilized enzymes tended to reach a steady state. After additional washing with buffer for 5 to 6 h, 40-55% of the immobilized enzymes were found to be in the active form.
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Affiliation(s)
- R Sipehia
- Artificial Cells and Organs Research Centre, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
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Chawla AS, Blais P, Hinberg I, Johnson D. Degradation of explanted polyurethane cardiac pacing leads and of polyurethane. Biomater Artif Cells Artif Organs 1988; 16:785-800. [PMID: 3219417 DOI: 10.3109/10731198809117569] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Polyurethane cardiac pacing leads explanted at autopsy and from reoperated patients were examined for degradation in the insulation. Scanning electron microscopy (SEM) analysis showed cracks on the polyurethane surface which were both parallel and perpendicular to the longitudinal axis of the lead. Surface analyses of leads were performed using Fourier-Transform Infra-red (FT-IR) spectrophotometry in the attenuated total reflectance mode. The FT-IR spectra of visibly deteriorated polyurethane from explanted lead sheaths were compared with that of unused polyurethane tubing used for such sheaths. Changes were most evident in the regions of 3000-2800, 1730 and 1368 cm-1. The observed alterations in the FT-IR spectra were consistent with a degradation mechanism involving oxidative chain cleavage in the polyurethane amorphous regions. New polyurethane tubing (Pellethane-Type 80A) was exposed to sodium hypochlorite to simulate a possible in-vivo process and generate reference material. Degradation with associated decreases in tensile strength and molecular weight was recorded. This study showed that polyurethane insulation used in pacing leads is susceptible to oxidative degradation.
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Affiliation(s)
- A S Chawla
- Bureau of Radiation and Medical Devices, Health and Welfare Canada, Ottawa, Ontario
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Chawla AS, Singh M, Murthy MS, Gupta M, Singh H. Anti-inflammatory action of ferulic acid and its esters in carrageenan induced rat paw oedema model. Indian J Exp Biol 1987; 25:187-9. [PMID: 3666817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Abstract
Plasma surface modification technique was used to add amino groups onto the surfaces of polypropylene beads by exposing them to anhydrous ammonia plasma. Through these amino groups, albumin was attached to the polypropylene beads. Attached albumin was further stabilized by crosslinking with glutaraldehyde. The effect of washing albuminated polypropylene beads with saline and human plasma was investigated. It was found that after initial rapid removal of albumin, the concentration of attached albumin tended to reach a steady-state. After 52 h of washing, the amount of albumin retained on the beads varied between 125 and 171 micrograms/cm2.
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Abstract
Propylene was polymerized at low pressure in a radio frequency plasma reactor. The plasma polymerized propylene (PPP) films were insoluble in toluene. Thermal analysis of PPP showed no phase transition took place up to 255 degrees C. From these results, it was concluded that PPP is a highly crosslinked polymer. To further characterize the deposited PPP, Fourier Transform infrared (FTIR) spectroscopy in the attenuated total reflection (ATR) mode was used. The deposited material was shown to be polymerized propylene as a spectrum of the material showed absorption bands characteristic of polypropylene.
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Abstract
The aggregation of insulin and of insulin protected with surfactants was studied by shaking at 37 degrees C in glass, in polypropylene and polystyrene vials, and in CPI and Auto-Syringe insulin syringes and infusion sets. Surfactants such as Pluronic 17R8 and 25R5 hastened the aggregation, whereas Pluronic F68 was effective in preventing it. Furthermore, there was no change in the immunoreactivity of insulin containing Pluronic F68 even after 8 days of shaking. Unprotected insulin aggregated in all the vials. There appears to be little problem with the commercial syringes tested, but the infusion sets could cause aggregation of insulin if used over an extended period of time. Although Pluronic F68 prevented insulin aggregation in situ, it extracted more impurities from the contacting plastics. Further development in materials and design of insulin sets and insulin containers appears necessary.
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Abstract
Lactic acid was polymerized using tetraphenyl tin as a catalyst. The molecular weight of the resultant poly(lactic acid) varied between 0.89 X 10(6) and 2.94 X 10(6) depending upon the concentration of the catalyst used. In-vivo degradation of the poly(lactic acid) samples having 4 different molecular weights were studies by implanting these in Wistar rats. It was found that at the end of a 48-week implantation period lower molecular weight poly(lactic acid) samples were degraded at a faster rate than the higher molecular weight samples.
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Abstract
Plasma polymerization techniques were used to deposit a layer of filler-free silicone rubber on a variety of substrate materials. The thickness of the deposited film was 0.5-0.8 micron. As it is the surface of the biomaterial that comes in direct contact with the body fluids, the surface of the biomaterial is of paramount importance. In this study, the plasma polymerized biomaterials were characterized. Thus, the scanning electron microscope (SEM) showed the surfaces to be smooth. To study the surface layer of the deposited polymer, Fourier-transform infrared spectrometry in the attenuated total reflection (ATR) mode was used. The deposited material was indeed silicone polymer with adsorption bands at 1262, 1020, and 802 cm-1 for the Si-CH3 bending, Si-0-Si stretching, and Si-CH3 bending, respectively. To find the bonding nature of the polymer, electron spectrometry for chemical analysis (ESCA) was used. The silicone polymer was shown to be highly cross-linked. To find the molecular weight between cross-links, swelling studies were done. Thus the results of the study show that the plasma polymerization could produce a filler-free silicone layer on a variety of substrate materials.
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Abstract
Cytotoxicity of a novel filler free silicone rubber (FFSR) was evaluated by studying its effect on mouse L929 cells. Silastic and a laboratory rubber tubing (RT) were used as control materials. Three different experimental methods were used. In method A, after six days of cell culturing in the sample extracts, there were 95, 80, and 50% of control viable cells for FFSR, Silastic, and RT, respectively. Similarly, in method B, after six days of direct contact between samples and the cells, there were 80, 40, and 20% of control viable cells for FFSR, Silastic, and RT, respectively. For the Agar Overlay Test, method C, the cells under the FFSR samples were normal and healthy compared to those under Silastic and RT. From these studies it was concluded that FFSR had the least cytotoxicity of the three materials studied.
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Abstract
Amino groups were added on to the surfaces of Celgard-2400 membranes by exposing them to an ammonia plasma. The presence of amino groups on the surfaces was detected by an attenuated total reflection Fourier Transform infrared spectrometer and by the Auger electron spectrometer. Through these amino groups, albumin was attached to the membranes. In some experiments, the attached albumin was further stabilized by cross-linking with glutaraldehyde. The effect of washing the albuminated membranes with saline and with plasma was investigated. It was observed that after the initial wash-out of albumin, the concentration of attached albumin tends to level off. The amount of albumin retained on the membranes varied between 275 to 357 micrograms/cm2.
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Abstract
Silicone coated Celgard-2400 and Silastic membranes were prepared by plasma polymerization of hexamethylcyclotrisiloxane. The adhesion of canine platelets and leucocytes was tested by passing whole blood from the anaesthetized mongrel dog in an ex-vivo shunt system. The silicone control Celgard and silicone coated Silastic membranes had fewer platelets and fewer leucocytes compared to those on the control Silastic membranes. Furthermore, these blood cells underwent fewer morphological changes on the silicone coated Celgard and Silastic compared to those on the control Silastic. From these observations the silicone coated biomaterials were judged to be better than the Silastic as far as the adhesion of platelets and leucocytes are concerned.
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Affiliation(s)
- H Singh
- Department of Pharmaceutical Sciences, Panjab University, Chandigarh, India
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Abstract
4 g% aqueous solutions of heparin were irradiated with the gamma radiation doses of 4.6 x 10(5) or 9.2 x 10(5) rads. The irradiated and also the non-irradiated heparin samples were fractionated using a Sephadex G-200 column. With radiation, the peak of the molecular weight distribution curves shifted toward the lower molecular weight. Also, the number average molecular weight decreased by 8.2 and 11.5% with the doses of 4.6 x 10(5) and 9.2 x 10(5) rads, respectively. The anticoagulant activity depended on the molecular weight of the heparin fractions. For the heparin fractions with molecular weights below 7,900, the anticoagulant activity decreased with radiation. Thus, for a heparin fraction with a molecular weight of 6,200, the anticoagulant activity decreased from 211 to 198 IU/mg after 4 h of irradiation.
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Abstract
The plasma polymerization of hexamethylcyclotrisiloxane (D3) and octamethylcyclotetrasiloxane (D4) over the microporous polypropylene membrane Celgard 2400, over polypropylene filter membranes, and over glass slides was investigated. The rate of polymer deposition was dependent upon the location of the substrate materials in the reaction vessel. The increase in weight of all the substrates was linear with the time of reaction, indicating a uniform polymerization rate. The rate of polymer deposition over polypropylene filters was found to be 2.27 micrograms/cm(2)/min for both D3, and D4, whereas over the glass slides it was 1.53 and 1.87 microgram/cm(2)/min for D3 and D4, respectively. The coated Celgard membranes showed better blood compatibility that Silastic sheeting or glass.
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Chawla AS. Preparation of silicone coated biomaterials using plasma polymerizations and their preliminary evaluations. Trans Am Soc Artif Intern Organs 1979; 25:287-93. [PMID: 524595 DOI: 10.1097/00002480-197902500-00052] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Chawla AS. A novel filler free silicone rubber biomaterial. II. Radiation chemical and physical evaluation. J Bioeng 1978; 2:231-40. [PMID: 711716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Hexamethylcyclotrisiloxane was polymerized at 60 degrees C by gamma radiation to yield filler free silicone rubber (FFSR). The G (crosslinking) value of 23.5 was found for the FFSR polymerized for 4 hours, compared to about 2 for the pure polydimethylsiloxane (PDMS). The sol fractions for both FFSR and cross-linked PDMS varied between 5-7%. The FFSR and the cross-linked PDMS both had tensile strength of about 1 kg per cm2 but FFSR was not brittle and could be extended as much as 500% before breaking. It is believed that the marked improvement in physical properties of FFSR is due to the formation of domains of highly cross-linked material which act as "internal filler".
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Abstract
To evaluate the thrombogenicity of the novel filler free silicone rubber (FFSR) prepared in our laboratory, its interactions with blood were studied. The test samples (FFSR) along with control Silastic samples were placed in an extracorporeal shunt and primed with sterilized normal saline. The blood from an anaesthetized and systemically heparinized dog was passed over these samples for predetermined time intervals. After washing, fixing, etc., the platelets adhering to the samples were counted under light microscopy. To study the morphological changes of the platelets adhering to the samples, they were examined under scanning electron microscope. The number of platelets adhering to the FFSR samples was very small compared to the Silastic samples. For example, when the blood was passed over the samples for 10 min the number of platelets sticking per 0.14 mm2 surface area was 10 for FFSR samples compared to 380 for Silastic. Furthermore, there were no leukocytes on FFSR samples compared to 10 on Silastic. From these studies, the novel filler free silicone rubber prepared in our laboratory was judged to be more compatible with formed elements of blood compared to the Silastic material.
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Chawla AS. Pure and filler free silicone rubber biomaterial; a new concept in preparing silicone rubber. J Bioeng 1976; 1:51-3. [PMID: 210159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Kapoor VK, Chawla AS, Gupta AK, Bedi KL. Studies on the oil of Xanthium strumarium. J AM OIL CHEM SOC 1976; 53:524. [PMID: 956593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Singh H, Chawla AS, Jindal AK, Conner AH, Rowe JW. Investigation of Erythrina spp. VII. Chemical constituents of Erythrina variegata var. orientalis bark. Lloydia 1975; 38:97-100. [PMID: 1134218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The petroleum ether extractive of the bark of Erythrina variegata var. orientalis was fractionated and shown to be composed of wax alcohols and wax acids, alkyl ferulates, alkyl phenolates, stigmasterol, sitosterol, campesterol and possibly citrostadienol/24-methylenelophenol. The ethanol extractive yielded chloroform-soluble and water-soluble bases, identified as erysovine and stachydrine, respectively.
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Chawla AS, Chang TM. Nonthrombogenic surface by radiation grafting of heparin: preparation, in-vitro and in-vivo studies. Biomater Med Devices Artif Organs 1974; 2:157-69. [PMID: 4441580 DOI: 10.3109/10731197409118960] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Singh H, Chawla AS. Investigation of Erythrina SPP. IV. Study of the chemical constituents of seeds of Erythrina variegata var. orientalis. Planta Med 1970; 19:71-74. [PMID: 5484886 DOI: 10.1055/s-0028-1099807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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