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Abstract
BACKGROUND The Huntingtin (HTT) N-terminal domains encoded by Huntingtin's (HTT) exon 1 consist of an N17 domain, the polyglutamine (polyQ) stretch and a proline-rich region (PRR). These domains are conserved in mammals and have been hypothesized to modulate HTT's functions in the developing and adult CNS, including DNA damage repair and autophagy. OBJECTIVE This study longitudinally characterizes the in vivo consequences of deleting the murine Htt N-terminal domains encoded by Htt exon 1. METHODS Knock-in mice with a deletion of Htt exon 1 sequences (HttΔE1) were generated and bred into the C57BL/6J congenic genetic background. Their behavior, DNA damage response, basal autophagy, and glutamatergic synapse numbers were evaluated. RESULTS Progeny from HttΔE1/+ intercrosses are born at the expected Mendelian frequency but with a distorted male to female ratio in both the HttΔE1/ΔE1 and Htt+/+ offspring. HttΔE1/ΔE1 adults exhibit a modest deficit in accelerating rotarod performance, and an earlier increase in cortical and striatal DNA damage with elevated neuronal pan-nuclear 53bp1 levels compared to Htt+/+ mice. However, a normal response to induced DNA damage, normal levels of basal autophagy markers, and no significant differences in corticocortical, corticostriatal, thalamocortical, or thalamostriatal synapses numbers were observed compared to controls. CONCLUSION Our results suggest that deletion of the Htt N-terminus encoded by the Htt exon 1 does not affect Htt's critical role during embryogenesis, but instead, may have a modest effect on certain motor tasks, basal levels of DNA damage in the brain, and Htt function in the testis.
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Affiliation(s)
- Elise M Braatz
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Emily A André
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Jeh-Ping Liu
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Scott O Zeitlin
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
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Franich NR, Basso M, André EA, Ochaba J, Kumar A, Thein S, Fote G, Kachemov M, Lau AL, Yeung SY, Osmand A, Zeitlin SO, Ratan RR, Thompson LM, Steffan JS. Striatal Mutant Huntingtin Protein Levels Decline with Age in Homozygous Huntington's Disease Knock-In Mouse Models. J Huntingtons Dis 2019; 7:137-150. [PMID: 29843246 PMCID: PMC6002862 DOI: 10.3233/jhd-170274] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Background: Huntington’s disease (HD) is a progressive neurodegenerative disorder associated with aging, caused by an expanded polyglutamine (polyQ) repeat within the Huntingtin (HTT) protein. In HD, degeneration of the striatum and atrophy of the cortex are observed while cerebellum is less affected. Objective: To test the hypothesis that HTT protein levels decline with age, which together with HTT mutation could influence disease progression. Methods: Using whole brain cell lysates, a unique method of SDS-PAGE and western analysis was used to quantitate HTT protein, which resolves as a monomer and as a high molecular weight species that is modulated by the presence of transglutaminase 2. HTT levels were measured in striatum, cortex and cerebellum in congenic homozygous Q140 and HdhQ150 knock-in mice and WT littermate controls. Results: Mutant HTT in both homozygous knock-in HD mouse models and WT HTT in control striatal and cortical tissues significantly declined in a progressive manner over time. Levels of mutant HTT in HD cerebellum remained high during aging. Conclusions: A general decline in mutant HTT levels in striatum and cortex is observed that may contribute to disease progression in homozygous knock-in HD mouse models through reduction of HTT function. In cerebellum, sustained levels of mutant HTT with aging may be protective to this tissue which is less overtly affected in HD.
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Affiliation(s)
- Nicholas R Franich
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Manuela Basso
- Centre for Integrative Biology, University of Trento, Trento, Italy
| | - Emily A André
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Joseph Ochaba
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, USA
| | - Amit Kumar
- Burke Medical Research Institute, White Plains, NY, USA.,Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY, USA.,Department of Neurology, Weill Medical College of Cornell University, New York, NY, USA
| | - Soe Thein
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA
| | - Gianna Fote
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA
| | - Marketta Kachemov
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, USA
| | - Alice L Lau
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA
| | - Sylvia Y Yeung
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA
| | - Alexander Osmand
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
| | - Scott O Zeitlin
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Rajiv R Ratan
- Burke Medical Research Institute, White Plains, NY, USA.,Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY, USA.,Department of Neurology, Weill Medical College of Cornell University, New York, NY, USA
| | - Leslie M Thompson
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, USA.,Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA.,Institute of Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, USA
| | - Joan S Steffan
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA.,Institute of Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, USA
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Lee JS, Lee Y, André EA, Lee KJ, Nguyen T, Feng Y, Jia N, Harris BT, Burns MP, Pak DTS. Inhibition of Polo-like kinase 2 ameliorates pathogenesis in Alzheimer's disease model mice. PLoS One 2019; 14:e0219691. [PMID: 31306446 PMCID: PMC6629081 DOI: 10.1371/journal.pone.0219691] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [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] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 06/28/2019] [Indexed: 12/19/2022] Open
Abstract
Alzheimer disease (AD) is a neurodegenerative disorder characterized by pathological hallmarks of neurofibrillary tangles and amyloid plaques. The plaques are formed by aggregation and accumulation of amyloid β (Aβ), a cleavage fragment of amyloid precursor protein (APP). Enhanced neuronal activity and seizure events are frequently observed in AD, and elevated synaptic activity promotes Aβ production. However, the mechanisms that link synaptic hyperactivity to APP processing and AD pathogenesis are not well understood. We previously found that Polo-like kinase 2 (Plk2), a homeostatic repressor of neuronal overexcitation, promotes APP β-processing in vitro. Here, we report that Plk2 stimulates Aβ production in vivo, and that Plk2 levels are elevated in a spatiotemporally regulated manner in brains of AD mouse models and human AD patients. Genetic disruption of Plk2 kinase function reduces plaque deposits and activity-dependent Aβ production. Furthermore, pharmacological Plk2 inhibition hinders Aβ formation, synapse loss, and memory decline in an AD mouse model. Thus, Plk2 links synaptic overactivity to APP β-processing, Aβ production, and disease-relevant phenotypes in vivo, suggesting that Plk2 may be a potential target for AD therapeutics.
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Affiliation(s)
- Ji Soo Lee
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Yeunkum Lee
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Emily A. André
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Kea Joo Lee
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Thien Nguyen
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Yang Feng
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Nuo Jia
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Brent T. Harris
- Department of Neurology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Mark P. Burns
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC, United States of America
| | - Daniel T. S. Pak
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
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André EA, Forcelli PA, Pak DT. What goes up must come down: homeostatic synaptic plasticity strategies in neurological disease. Future Neurol 2018; 13:13-21. [PMID: 29379396 DOI: 10.2217/fnl-2017-0028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [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: 10/09/2017] [Accepted: 12/07/2017] [Indexed: 11/21/2022]
Abstract
Brain activity levels are tightly regulated to minimize imbalances in activity state. Deviations from the normal range of activity are deleterious and often associated with neurological disorders. To maintain optimal levels of activity, regulatory mechanisms termed homeostatic synaptic plasticity establish desired 'set points' for neural activity, monitor the network for deviations from the set point and initiate compensatory responses to return activity to the appropriate level that permits physiological function [1,2]. We speculate that impaired homeostatic control may contribute to the etiology of various neurological disorders including epilepsy and Alzheimer's disease, two disorders that exhibit hyperexcitability as a key feature during pathogenesis. Here, we will focus on recent progress in developing homeostatic regulation of neural activity as a therapeutic tool.
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Affiliation(s)
- Emily A André
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington DC 20057, USA
| | - Patrick A Forcelli
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington DC 20057, USA
| | - Daniel Ts Pak
- Department of Pharmacology & Physiology, Georgetown University Medical Center, Washington DC 20057, USA
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André EA, Braatz EM, Liu JP, Zeitlin SO. Generation and Characterization of Knock-in Mouse Models Expressing Versions of Huntingtin with Either an N17 or a Combined PolyQ and Proline-Rich Region Deletion. J Huntingtons Dis 2017; 6:47-62. [PMID: 28211815 PMCID: PMC5389044 DOI: 10.3233/jhd-160231] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Background: The polyglutamine (polyQ) stretch of the Huntingtin protein (HTT) in mammals is flanked by a highly conserved 17 amino acid N-terminal domain (N17), and a proline-rich region (PRR). The PRR is a binding site for many HTT-interacting proteins, and the N17 domain regulates several normal HTT functions, including HTT’s ability to associate with membranes and organelles. Objective: This study investigates the consequence of deleting mouse Huntingtin’s (Htt’s) N17 domain or a combination of its polyQ stretch and PRR (QP) on normal Htt function in mice. Methods: Knock-in mice expressing versions of Htt lacking either the N17 domain (HttΔN17) or both the polyQ and PRR domains (HttΔQP) were generated, and their behavior, autophagy function, and neuropathology were evaluated. Results: Homozygous and hemizygous HttΔQP/ΔQP, HttΔN17/ΔN17, HttΔQP/–, and HttΔN17/– mice were generated at the expected Mendelian frequency. HttΔQP/ΔQP mutants exhibit improvements in motor coordination compared to controls (Htt+/+). In contrast, HttΔN17/ΔN17 mutants do not exhibit any changes in motor coordination, but they do display variable changes in spatial learning that are dependent on their age at testing. Neither mutant exhibited any changes in basal autophagy in comparison to controls, but thalamostriatal synapses in the dorsal striatum of 24-month-old HttΔN17/ΔN17 mice were decreased compared to controls. Conclusions: These findings support the hypothesis that Htt’s N17 and QP domains are dispensable for its critical functions during early embryonic development, but are likely more important for Htt functions in CNS development or maintenance.
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Affiliation(s)
| | | | | | - Scott O. Zeitlin
- Correspondence to: Scott O. Zeitlin, Ph.D., Department of Neuroscience, University of Virginia School of Medicine, 409 Lane Rd., Box 801392, MR4-5022, Charlottesville, VA 22908 USA. Tel.: +1 434 924 5011; Fax: +1 434 982 4380; E-mail:
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Abstract
BACKGROUND Helicobacter pylori infection in the stomach is associated with gastric and duodenal ulcers, gastric cancers and gastric lymphoma. The organism is transmitted by ingestion, but the oral-oral route and the fecal-oral route are also suggested. The prevalence of infection with H. pylori in developing countries, including Brazil, is higher than in developed countries. PURPOSE This study aimed to evaluate the role of the oral cavity as a reservoir of this species, by evaluating the occurrence of H. pylori in supragingival dental plaque and in saliva of Brazilian dyspeptic patients, whether harboring the organism or not in the stomach. MATERIAL AND METHODS Forty-nine patients reporting dyspeptic symptoms were subjected to oral clinical examination and collection of saliva and supragingival dental plaque samples prior to the endoscopic examination. The detection of H. pylori in oral samples was performed by PCR using 16S rRNA primers. The bacteria were detected in stomach by means of the rapid urease test. RESULTS Helicobacter pylori was detected in the stomach of 20 of 49 subjects reporting dyspeptic symptoms. The organism was detected in only one supragingival plaque sample, obtained from a patient positive for the urease test in the stomach and in none of the salivary samples. CONCLUSION Supragingival dental plaque and saliva may not be relevant reservoirs of H. pylori.
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Affiliation(s)
- S Kignel
- Department of Stomatology, School of Dentistry, Universidade de São Paulo, São Paulo, Brazil
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Abstract
BACKGROUND AND OBJECTIVES Considering the high prevalence of stomach cancer in the northern region of Brazil and the recognized relationship between chronic gastric inflammation caused by Helicobacter pylori, and its carcinogenic potential, the objective we had with this study was to investigate the presence of the microorganism in macro and microscopic presentations of neoplasm in different regions of the stomach, and in non-malignant lesions concomitant to the adenocarcinoma in patients originating from the metropolitan area of Belém (State of Pará, Brazil). METHODS Examinations were made on 172 patients divided into two groups: group I, formed by 75 patients with gastric carcinoma, and group II, formed by 97 patients with mild enanthematic gastritis, considered control group. The diagnosis was obtained during endoscopic examination and the respective biopsy. Gastric neoplasms were classified macroscopically in accordance with Borrmann's classification, and microscopically in accordance with Laurén's classification. In group I, 54 patients were male and 21 female while in group II, 22 patients were male and 75 female. The average age in group I was 61.2 years (range 27 to 86 years), while in group II it was 37.5 years (range 16 to 69 years). Thin sections were prepared and stained using the hematoxylin-eosin method. In the Helicobacter pylori research, the modified Gram stain was utilized. Statistical analysis was done by utilizing the chi-squared (chi 2) test, Mann-Whitney test (U), and Fisher's exact test. RESULTS The results showed the detection of Helicobacter pylori were significantly greater in patients with mild enanthematic gastritis than in patients with gastric carcinoma. The presence of Helicobacter pylori in patients with gastric carcinoma and mild enanthematic gastritis was significantly greater in the antral region than in other gastric regions. Helicobacter pylori detection in patients with gastric carcinoma did not present a significant difference in relation to the macroscopic aspect of the tumor either intestinal or diffuse histological types. CONCLUSIONS These data suggest the presence of the bacteria is predominant in the antral region and it does not show relation with the macroscopic types or histological intestinal or diffuse types of gastric carcinoma.
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Affiliation(s)
- L P Pereira
- Department of Surgical Gastroenterology, Hospital do Servidor Público Estadual, São Paulo, SP
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8
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Abstract
BACKGROUND The antineoplastic drug cisplatin has been widely used for the treatment of cancer in humans but its use has been limited by vomiting and diarrhoea. Cisplatin releases 5-hydroxytryptamine into the gut which is thought to be the major mediator of cisplatin induced vomiting. AIM To determine whether cisplatin affects fluid and electrolyte transport in rat jejunum and whether this change can be modulated by the 5-hydroxytryptamine3 receptor antagonist, ondansetron. METHODS Jejunal perfusion in rats in vivo was performed one hour after intraperitoneal cisplatin (5 and 10 mg/kg) administration. The effect of pretreatment with subcutaneous ondansetron 300 microg/kg was investigated. RESULTS Median net fluid absorption after cisplatin 10 mg/kg (67 microl/min/g dry intestinal weight (interquartile range 46 to 100); n = 15) was reduced compared with controls (120 (107 to 151) microl/min/g; n = 13; p<0.001). Ondansetron reversed the impairment of jejunal fluid absorption produced by cisplatin to normal (161 (130 to 176) microl/min/g; n = 11; p<0.001). Electrolyte movement paralleled fluid movement. Jejunal histological examination of sections from cisplatin treated animals showed villus damage, which was not prevented by pretreatment with ondansetron. CONCLUSION These findings suggest that diarrhoea during cisplatin therapy may be due to altered fluid transport in the small bowel. The reversal of fluid transport to normal in the presence of a 5-hydroxytryptamine3 receptor antagonist suggests that 5-hydroxytryptamine is a local mediator in the small intestine.
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Affiliation(s)
- C P Bearcroft
- Digestive Diseases Research Centre, St Bartholomew's and Royal London, School of Medicine and Dentistry, Turner St, London E1 2AD, UK
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Bearcroft CP, André EA, Farthing MJ. In vivo effects of the 5-HT3 antagonist alosetron on basal and cholera toxin-induced secretion in the human jejunum: a segmental perfusion study. Aliment Pharmacol Ther 1997; 11:1109-14. [PMID: 9663837 DOI: 10.1046/j.1365-2036.1997.d01-1389.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.0] [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: 12/08/2022]
Abstract
BACKGROUND 5-hydroxytryptamine type 3 receptor antagonists have been shown to reduce fluid and electrolyte secretion or promote absorption in experimental models of small intestinal secretion. The aim of this study was to compare the effects of a single dose (4 mg) of the 5-hydroxytryptamine type 3 receptor antagonist alosetron and placebo on jejunal fluid and electrolyte movement in humans under basal conditions (n = 7) and following cholera toxin-induced secretion (n = 5) in a randomized, double-blind, crossover design over two separate study periods. METHODS One hour after oral alosetron or placebo, jejunal intubation was performed. A 30 cm segment of jejunum, isolated by two occluding balloons, was exposed to 15 microg of purified cholera toxin for 2 h prior to triple lumen perfusion with a plasma electrolyte solution containing [14C]-polyethylene glycol as a nonabsorbable volume marker. In the basal study, intestinal perfusion was performed without exposure to cholera toxin. Collection and analysis of the effluent from the jejunal segment allowed fluid and electrolyte movement to be calculated. RESULTS Alosetron treatment increased basal jejunal fluid absorption (median 5.1 mL/cm/h [interquartile range 4.2 to 7.1] compared with placebo (3.8 [3.6 to 4.3] P = 0.028, two sided Wilcoxon matched pairs signed rank test)). However, following establishment of a secretory state by cholera toxin, alosetron failed to significantly promote absorption or reduce secretion (0.3 [-1.2 to 1.2] compared to placebo (-4.3 [-7.7 to -1.3] P = 0.14)). Adverse events during the study, which included anorexia, nausea, dizziness and loose bowel movements, were not considered to be clinically important. There were no clinically significant changes in laboratory parameters. CONCLUSION The 5-hydroxytyptamine type 3 receptor antagonist, alosetron, increased basal fluid absorption in normal human small intestine but failed to have a beneficial effect in cholera toxin-induced secretion.
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Affiliation(s)
- C P Bearcroft
- Digestive Diseases Research Centre, St Bartholomew's and Royal London School of Medicine and Dentistry, UK
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André EA, Costa PL, Guarita DR, Meirelles Filho JS, Laudanna AA. Changes in capillary permeability during severe experimental acute pancreatitis in rats. Rev Hosp Clin Fac Med Sao Paulo 1996; 51:184-8. [PMID: 9216096] [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: 02/04/2023]
Abstract
Abnormalities of microcirculation are thought to have an important role in the pathogenesis of severe acute pancreatitis (SAP) and in the associated multiple organic failure. We studied changes in capillary permeability during experimental SAP in rats. Necrotizing acute pancreatitis was induced by retrograde injection of sodium taurocholate in pancreatic ducts in rats (n = 30). The animals were distributed in three groups in which the spaces of compartmental distribution as well as the tissue distribution of labeled tracers were evaluated with the use of erythrocytes and albumin tagged with radioactive chromium, apart from determining the volume of total body water. All the studies were carried out four hours after the induction of acute pancreatitis and the administration of radioactive tracers.
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Affiliation(s)
- E A André
- Department of Gastroenterology, Medical School, University of São Paulo, Brazil
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Laudanna AA, André EA, Forjáz Júnior NG, de Almeida TR, Gushi N, Meirelles Filho JDS, Germek OA. [Serum levels of gastrin, calcium, phosphorus and creatinine in patients with chronic renal insufficiency]. Rev Hosp Clin Fac Med Sao Paulo 1982; 37:251-4. [PMID: 7182906] [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: 01/23/2023]
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