Tandem antifibrotic actions of L-arginine supplementation and low protein diet during the repair phase of experimental glomerulonephritis

Tandem antifibrotic actions of L-arginine supplementation and low protein diet during the repair phase of experimental glomerulonephritis.BackgroundBased upon the central role transforming growth factor-beta (TGF-β) overexpression appears to play in renal fibrotic diseases, we have recently advocated reduction of TGF-β as a therapeutic target. As part of efforts to determine the strength of this approach, we have undertaken studies to quantitate the effects of currently used and promising therapies in terms of their potential to reduce markers of disease in anti-thymocyte-serum (ATS)-glomerulonephritis in the rat. Here we assess the therapeutic effect of L-arginine supplementation, which has been shown to reduce fibrosis in a number of hypertensive models, given alone or in combination with low protein diet and started 24 hours after disease induction.MethodsGlomerulonephritis was induced by intravenous injection of OX-7 monoclonal antibody into 200g Sprague-Dawley rats. Twenty-four hours later animals were placed in groups that were either untreated, treated with 1% L-arginine in drinking water or 6% protein diets or both. On the fifth day of disease 24-hour urine specimens were collected and systemic blood pressure was measured. On the sixth day rats were anesthetized. Kidneys were perfused, tissue was taken for PAS staining and glomeruli were isolated. Aliquots of glomeruli were used for RNA preparation and for culture to determine 72-hour production of TGF-β, fibronectin and plasminogen activator-type 1 (PAI-1), which were assayed by ELISA on culture supernatants. Measures of nitrate and nitrite (NOx) production included plasma NOx, urinary NOx and glomerular production of NOx in culture.ResultsAll disease measures except proteinuria and including matrix accumulation, TGF-β, fibronectin and PAI-1 production and mRNA expression for TGF-β, fibronectin and PAI-1 were significantly and similarly reduced by about 50% in groups treated with L-arginine or with low protein diet. Proteinuria was reduced in low protein treated but not in L-arginine supplemented rats. Neither systemic blood pressure nor measures of NO synthesis showed differences between groups that could be attributed to L-arginine supplementation. In contrast, disease-related increases in glomerular production of NOx were markedly reduced by low protein. Combined therapy resulted in small, but statistically significant decreases in most measures of disease.ConclusionsL-arginine supplementation reduces fibrotic disease in ATS-induced glomerulonephritis if started after disease induction. The absence of evidence for increased NO production related to L-arginine supplementation suggests that L-arginine is acting here through different pathways from those demonstrated in hypertensive models of disease. The data support the ideas that TGF-β reduction is a valid therapeutic target and that quantitation of TGF-β reduction is a useful approach for comparing antifibrotic drug candidates

Glomerular matrix accumulation is linked to inhibition of the plasmin protease system

Glomerular matrix accumulation is linked to inhibition of the plasmin protease system. TGF-β plays a pivotal role in the pathological accumulation of extracellular matrix in experimental glomerulonephritis. Increased TGF-β expression leads to increased synthesis and deposition of extracellular matrix components while administration of antiserum to TGF-β suppresses the major manifestations of the disease. We hypothesized that TGF-β might also enhance matrix accumulation by decreasing matrix turnover via effects on protease/protease inhibitor balance. Plasmin is a potent protease capable of degrading a variety of matrix molecules. Plasmin generation from plasminogen is regulated by plasminogen activator(s) (PA) and plasminogen activator inhibitor(s) (PAI). In this study PA activity was markedly reduced and PAI-1 synthesis dramatically increased when TGF-β was added to normal glomeruli. Diseased glomeruli also showed decreased PA activity, increased PAI-1 synthesis and increased PAI-1 deposition into matrix. Administration of anti-TGF-β serum to glomerulonephritic rats blocked the expected increase in glomerular PAI-1 deposition. Thus changes in the PA/PAI balance favoring accumulation of matrix are induced by TGF-β in normal glomeruli and are present in nephritic glomeruli when endogenous TGF-β production is high. Our findings implicate the plasmin protease system in tissue repair following acute glomerular injury and suggest another mechanism by which TGF-β enhances the matrix accumulation characteristic of many glomerular diseases

Combining TGF-β inhibition and angiotensin II blockade results in enhanced antifibrotic effect

Combining TGF-β inhibition and angiotensin II blockade results in enhanced antifibrotic effects.BackgroundAlthough angiotensin II (Ang II) blockade is rapidly becoming standard antifibrotic therapy in renal diseases, current data suggest that Ang II blockade alone cannot stop fibrotic disease. New therapies, such as antibodies to transforming growth factor-β (TGF-β), or drug combinations will be required to further slow or halt disease progression. Here, using the anti-Thy1 model of glomerulonephritis, the maximally therapeutic dose of the TGF-β neutralizing mouse monoclonal antibody (1D11) was determined and compared with the maximally effective dose of enalapril. Then, the effect of combining both treatments at maximal doses was determined.MethodsAfter disease induction with the anti-Thy1 antibody, OX-7, increasing doses of 1D11 were given intraperitoneally (IP) on days 1, 3, and 5. Enalapril was administered in drinking water from day 1. The fibrotic response was assessed at day 6.Results1D11 dose-dependently reduced fibrosis, with the 0.5 and 5 mg/kg doses showing maximal therapeutic effects, reducing period-acid Schiff (PAS) staining by 56% and 45%, respectively. Fibronectin and collagen I staining was reduced by 32% to 36%, respectively. Glomerular mRNA and production of fibronectin, plasminogen activator inhibitor-1 (PAI-1), TGF-β1, and p-Smad2 protein were also reduced. The maximal therapeutic effects of 1D11 and enalapril alone were very similar. However, combination therapy led to further reduction in disease. Notably, matrix deposition was reduced by 80%.ConclusionWhile 1D11 or enalapril at maximal doses reduce fibrosis equally, simultaneous blockade of Ang II and TGF-β reduces fibrotic disease considerably more, offering hope that such drug combinations may confer a therapeutic advantage over angiotensin blockade alone

Association in Long-Evans hooded rats of red cell 2,3-diphosphoglycerate levels with hemoglobin types

Two sublines of commercially available Long-Evans hooded rats have been developed by genetic selection. These sublines have widely differing levels of erythrocyte 2,3-diphosphoglycerate (DPG) due to different alleles at a single genetic locus. In the present work, it is shown that rats from the commercial population are also polymorphic at a hemoglobin locus, probably involving two alleles of the III β-globin chain locus. Particular hemoglobin types have been found to be strongly associated with certain DPG types, not only in the high-DPG and low-DPG lines but also in the commercial population. Two explanations for this association are considered. One is a single-locus hypothesis, with hemoglobin allelic variation causing DPG variation, and the other is a two-locus hypothesis, with marked linkage disequilibrium.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44130/1/10528_2004_Article_BF00484727.pd

Thinking like a man? The cultures of science

Culture includes science and science includes culture, but conflicts between the two traditions persist, often seen as clashes between interpretation and knowledge. One way of highlighting this false polarity has been to explore the gendered symbolism of science. Feminism has contributed to science studies and the critical interrogation of knowledge, aware that practical knowledge and scientific understanding have never been synonymous. Persisting notions of an underlying unity to scientific endeavour have often impeded rather than fostered the useful application of knowledge. This has been particularly evident in the recent rise of molecular biology, with its delusory dream of the total conquest of disease. It is equally prominent in evolutionary psychology, with its renewed attempts to depict the fundamental basis of sex differences. Wars over science have continued to intensify over the last decade, even as our knowledge of the political, economic and ideological significance of science funding and research has become ever more apparent

ABM Clinical Protocol #18: Use of Antidepressants in Breastfeeding Mothers

A central goal of The Academy of Breastfeeding Medicine is the development of clinical protocols for managing common medical problems that may impact breastfeeding success. These protocols serve only as guidelines for the care of breastfeeding mothers and infants and do not delineate an exclusive course of treatment or serve as standards of medical care. Variations in treatment may be appropriate according to the needs of an individual patient

Generational Association Studies of Dopaminergic Genes in Reward Deficiency Syndrome (RDS) Subjects: Selecting Appropriate Phenotypes for Reward Dependence Behaviors

Abnormal behaviors involving dopaminergic gene polymorphisms often reflect an insufficiency of usual feelings of satisfaction, or Reward Deficiency Syndrome (RDS). RDS results from a dysfunction in the “brain reward cascade,” a complex interaction among neurotransmitters (primarily dopaminergic and opioidergic). Individuals with a family history of alcoholism or other addictions may be born with a deficiency in the ability to produce or use these neurotransmitters. Exposure to prolonged periods of stress and alcohol or other substances also can lead to a corruption of the brain reward cascade function. We evaluated the potential association of four variants of dopaminergic candidate genes in RDS (dopamine D1 receptor gene [DRD1]; dopamine D2 receptor gene [DRD2]; dopamine transporter gene [DAT1]; dopamine beta-hydroxylase gene [DBH]). Methodology: We genotyped an experimental group of 55 subjects derived from up to five generations of two independent multiple-affected families compared to rigorously screened control subjects (e.g., N = 30 super controls for DRD2 gene polymorphisms). Data related to RDS behaviors were collected on these subjects plus 13 deceased family members. Results: Among the genotyped family members, the DRD2 Taq1 and the DAT1 10/10 alleles were significantly (at least p < 0.015) more often found in the RDS families vs. controls. The TaqA1 allele occurred in 100% of Family A individuals (N = 32) and 47.8% of Family B subjects (11 of 23). No significant differences were found between the experimental and control positive rates for the other variants. Conclusions: Although our sample size was limited, and linkage analysis is necessary, the results support the putative role of dopaminergic polymorphisms in RDS behaviors. This study shows the importance of a nonspecific RDS phenotype and informs an understanding of how evaluating single subset behaviors of RDS may lead to spurious results. Utilization of a nonspecific “reward” phenotype may be a paradigm shift in future association and linkage studies involving dopaminergic polymorphisms and other neurotransmitter gene candidates

individual participant data meta-analysis of randomised trials study protocol

Introduction Parenteral anticoagulants may improve outcomes in patients with cancer by reducing risk of venous thromboembolic disease and through a direct antitumour effect. Study-level systematic reviews indicate a reduction in venous thromboembolism and provide moderate confidence that a small survival benefit exists. It remains unclear if any patient subgroups experience potential benefits. Methods and analysis First, we will perform a comprehensive systematic search of MEDLINE, EMBASE and The Cochrane Library, hand search scientific conference abstracts and check clinical trials registries for randomised control trials of participants with solid cancers who are administered parenteral anticoagulants. We anticipate identifying at least 15 trials, exceeding 9000 participants. Second, we will perform an individual participant data meta-analysis to explore the magnitude of survival benefit and address whether subgroups of patients are more likely to benefit from parenteral anticoagulants. All analyses will follow the intention-to- treat principle. For our primary outcome, mortality, we will use multivariable hierarchical models with patient-level variables as fixed effects and a categorical trial variable as a random effect. We will adjust analysis for important prognostic characteristics. To investigate whether intervention effects vary by predefined subgroups of patients, we will test interaction terms in the statistical model. Furthermore, we will develop a risk-prediction model for venous thromboembolism, with a focus on control patients of randomised trials. Ethics and dissemination Aside from maintaining participant anonymity, there are no major ethical concerns. This will be the first individual participant data meta-analysis addressing heparin use among patients with cancer and will directly influence recommendations in clinical practice guidelines. Major cancer guideline development organisations will use eventual results to inform their guideline recommendations. Several knowledge users will disseminate results through presentations at clinical rounds as well as national and international conferences. We will prepare an evidence brief and facilitate dialogue to engage policymakers and stakeholders in acting on findings. Trial registration number PROSPERO CRD4201300352

Distinguishing Type 2 Diabetes from Type 1 Diabetes in African American and Hispanic American Pediatric Patients

To test the hypothesis that clinical observations made at patient presentation can distinguish type 2 diabetes (T2D) from type 1 diabetes (T1D) in pediatric patients aged 2 to 18.Medical records of 227 African American and 112 Hispanic American pediatric patients diagnosed as T1D or T2D were examined to compare parameters in the two diseases. Age at presentation, BMI z-score, and gender were the variables used in logistic regression analysis to create models for T2D prediction.The regression-based model created from African American data had a sensitivity of 92% and a specificity of 89%; testing of a replication cohort showed 91% sensitivity and 93% specificity. A model based on the Hispanic American data showed 92% sensitivity and 90% specificity. Similarities between African American and Hispanic American patients include: (1) age at onset for both T1D and T2D decreased from the 1980s to the 2000s; (2) risk of T2D increased markedly with obesity. Racial/ethnic-specific observations included: (1) in African American patients, the proportion of females was significantly higher than that of males for T2D compared to T1D (p<0.0001); (2) in Hispanic Americans, the level of glycated hemoglobin (HbA1c) was significantly higher in T1D than in T2D (p<0.002) at presentation; (3) the strongest contributor to T2D risk was female gender in African Americans, while the strongest contributor to T2D risk was BMI z-score in Hispanic Americans.Distinction of T2D from T1D at patient presentation was possible with good sensitivity and specificity using only three easily-assessed variables: age, gender, and BMI z-score. In African American pediatric diabetes patients, gender was the strongest predictor of T2D, while in Hispanic patients, BMI z-score was the strongest predictor. This suggests that race/ethnic specific models may be useful to optimize distinction of T1D from T2D at presentation