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1.  Alterations of renal phenotype and gene expression profiles due to protein overload in NOD-related mouse strains 
BMC Nephrology  2005;6:17.
Background
Despite multiple causes, Chronic Kidney Disease is commonly associated with proteinuria. A previous study on Non Obese Diabetic mice (NOD), which spontaneously develop type 1 diabetes, described histological and gene expression changes incurred by diabetes in the kidney. Because proteinuria is coincident to diabetes, the effects of proteinuria are difficult to distinguish from those of other factors such as hyperglycemia. Proteinuria can nevertheless be induced in mice by peritoneal injection of Bovine Serum Albumin (BSA). To gain more information on the specific effects of proteinuria, this study addresses renal changes in diabetes resistant NOD-related mouse strains (NON and NOD.B10) that were made to develop proteinuria by BSA overload.
Methods
Proteinuria was induced by protein overload on NON and NOD.B10 mouse strains and histology and microarray technology were used to follow the kidney response. The effects of proteinuria were assessed and subsequently compared to changes that were observed in a prior study on NOD diabetic nephropathy.
Results
Overload treatment significantly modified the renal phenotype and out of 5760 clones screened, 21 and 7 kidney transcripts were respectively altered in the NON and NOD.B10. Upregulated transcripts encoded signal transduction genes, as well as markers for inflammation (Calmodulin kinase beta). Down-regulated transcripts included FKBP52 which was also down-regulated in diabetic NOD kidney. Comparison of transcripts altered by proteinuria to those altered by diabetes identified mannosidase 2 alpha 1 as being more specifically induced by proteinuria.
Conclusion
By simulating a component of diabetes, and looking at the global response on mice resistant to the disease, by virtue of a small genetic difference, we were able to identify key factors in disease progression. This suggests the power of this approach in unraveling multifactorial disease processes.
doi:10.1186/1471-2369-6-17
PMCID: PMC1334202  PMID: 16371158
2.  Urinary Transforming Growth Factor-beta 1 as a marker of response to immunosuppressive treatment, in patients with crescentic nephritis 
BMC Nephrology  2005;6:16.
Background
Crescentic nephritis is characterized by formation of cellular crescents that soon become fibrotic and result in irreversible damage, unless an effective immunosuppressive therapy is rapidly commenced. TGF-β1 is involved in the development of crescents through various pathways. The aim of this study was to identify whether the determination of urinary TGF-β1 levels in patients with crescentic nephritis could be used as a marker of response to treatment.
Methods
Fifteen patients with crescentic nephritis were included in the study. The renal expression of TGF-β1 was estimated in biopsy sections by immunohistochemistry and urinary TGF-β1 levels were determined by quantitative sandwich enzyme immunoassay (EIA). TGF-β1 levels were determined at the time of renal biopsy, before the initiation of immunosuppressive treatment (corticosteroids, cyclophosphamide and plasma exchange). Twelve patients with other types of proliferative glomerulonephritis and ten healthy subjects were used as controls.
Results
Improvement of renal function with immunosuppressive therapy was observed in 6 and stabilization in 4 patients (serum creatinine from 3.2 ± 1.5 to 1.4 ± 0.1 mg/dl and from 4.4 ± 1.2 to 4.1 ± 0.6 mg/dl, respectively). In 5 patients, with severe impairment of renal function who started on dialysis, no improvement was noted. The main histological feature differentiating these 5 patients from others with improved or stabilized renal function was the percentage patients with poor response to treatment were the percentage of glomeruli with crescents and the presence of ruptured Bowman's capsule and glomerular necrosis. Urinary TGF-β1 levels were significantly higher in patients who showed no improvement of renal function with immunosuppressive therapy (930 ± 126 ng/24 h vs. 376 ± 84 ng/24 h, p < 0.01). TGF-β1 was identified in crescents and tubular epithelial cells, whereas a significant correlation of TGF-β1 immunostaining with the presence of fibrocellular cresents was observed (r = 0.531, p < 0,05).
Conclusion
Increased TGF-β1 renal expression and urinary excretion that is related to the response to immunosuppressive therapy was observed in patients with crescentic nephritis. Evaluation of urinary TGF-β1 levels may be proved a useful marker of clinical outcome in patients with crescentic nephritis.
doi:10.1186/1471-2369-6-16
PMCID: PMC1327665  PMID: 16367998
3.  Experimental glomerulonephritis induced by hydrocarbon exposure: A systematic review 
BMC Nephrology  2005;6:15.
Background
Much epidemiological evidence suggests that hydrocarbon exposure may induce glomerulonephritis and worsen its course in many patients. The mechanisms are unknown, however, no specific microscopic pattern has been identified, and it has also been argued that hydrocarbon exposure causes tubular damage mainly. Studying experimental animals may best answer these questions, and as no systematic review of glomerulonephritis produced experimentally by hydrocarbon exposure has been performed previously, I found it relevant to search for and analyse such studies.
Methods
Animal experiments having mimicked human glomerulonephritis by hydrocarbon exposure were sought on Medline and Toxnet
Results
Twenty-six experiments using thirteen different hydrocarbons were identified. Several human subtypes were observed including IgA nephritis, mesangial, proliferative and extracapillary glomerulonephritis, focal and focal-segmental sclerosis, minimal change nephropathy, anti-GBM and anti-TBM nephritis, and glomerulonephritis associated with peiarteritis nodosa. Glomerular proteinuria was seen in 10/12 experiments that included urine analyses, and renal failure in 5/8 experiments that included measurements of glomerular function. All experiments resulted in various degrees of tubular damage as well. In most studies, where the animals were examined at different times during or after the exposure, the renal microscopic and functional changes were seen immediately, whereas deposits of complement and immunoglobulins appeared late in the course, if at all.
Conclusion
These experiments are in accord with epidemiological evidence that hydrocarbon exposure may cause glomerulonephritis and worsen renal function. Probable mechanisms include an induction of autologous antibodies and a disturbance of normal immunological functions. Also, tubular damage may increase postglomerular resistance, resulting in a glomerular deposition of macromolecules. In most models a causal role of glomerular immune complex formation was unlikely, but may rather have been a secondary phenomenon. As most glomerulonephritis subgroups were seen and as some of the hydrocarbons produced more than one subgroup, the microscopic findings in a patient cannot be used as a clue to the causation of his disease. By the same reason, the lack of a specific histological pattern in patients with glomerulonephritis assumed to have been caused by hydrocarbon exposure is not contradictive.
doi:10.1186/1471-2369-6-15
PMCID: PMC1334181  PMID: 16354301
4.  The IgA nephropathy Biobank. An important starting point for the genetic dissection of a complex trait 
BMC Nephrology  2005;6:14.
Background
IgA nephropathy (IgAN) or Berger's disease, is the most common glomerulonephritis in the world diagnosed in renal biopsied patients. The involvement of genetic factors in the pathogenesis of the IgAN is evidenced by ethnic and geographic variations in prevalence, familial clustering in isolated populations, familial aggregation and by the identification of a genetic linkage to locus IGAN1 mapped on 6q22–23. This study seems to imply a single major locus, but the hypothesis of multiple interacting loci or genetic heterogeneity cannot be ruled out. The organization of a multi-centre Biobank for the collection of biological samples and clinical data from IgAN patients and relatives is an important starting point for the identification of the disease susceptibility genes.
Description
The IgAN Consortium organized a Biobank, recruiting IgAN patients and relatives following a common protocol. A website was constructed to allow scientific information to be shared between partners and to divulge obtained data (URL: ). The electronic database, the core of the website includes data concerning the subjects enrolled. A search page gives open access to the database and allows groups of patients to be selected according to their clinical characteristics. DNA samples of IgAN patients and relatives belonging to 72 multiplex extended pedigrees were collected. Moreover, 159 trios (sons/daughters affected and healthy parents), 1068 patients with biopsy-proven IgAN and 1040 healthy subjects were included in the IgAN Consortium Biobank. Some valuable and statistically productive genetic studies have been launched within the 5th Framework Programme 1998–2002 of the European project No. QLG1-2000-00464 and preliminary data have been published in "Technology Marketplace" website: .
Conclusion
The first world IgAN Biobank with a readily accessible database has been constituted. The knowledge gained from the study of Mendelian diseases has shown that the genetic dissection of a complex trait is more powerful when combined linkage-based, association-based, and sequence-based approaches are performed. This Biobank continuously expanded contains a sample size of adequately matched IgAN patients and healthy subjects, extended multiplex pedigrees, parent-child trios, thus permitting the combined genetic approaches with collaborative studies.
doi:10.1186/1471-2369-6-14
PMCID: PMC1318455  PMID: 16329758
5.  Smoking, oxidative stress and inflammation: Impact on resting energy expenditure in diabetic nephropathy 
BMC Nephrology  2005;6:13.
Background
Inflammation is associated with increased resting energy expenditure (REE) in patients with chronic kidney disease. Oxidative stress, on the other hand, appears not to increase REE. Smoking is a common mechanism for generating oxidative stress and inflammation. Whether smokers have increased REE and if so, whether it is accounted for by the pro-oxidant and inflammatory state is not known.
Methods
A case control study of 11 smokers and 24 non-smokers with overt diabetic nephropathy was performed to evaluate the chronic effect of smoking on REE. REE (indirect calorimetry), glomerular filtration rate (iothalamate clearance), markers of oxidative stress (urinary and plasma malondialdehyde (MDA), and protein carbonyls) and inflammation (C-reactive protein, tumor necrosis factor-alpha, interleukin-6) were measured on two occasions four months apart.
Results
Biomarkers of inflammation (C-reactive protein) and oxidative stress (urinary and plasma MDA) were increased in smokers. REE was increased in smokers, 24.3 kcal/kg/day compared to 21 kcal/kg/day (p = 0.009) in non-smokers. After adjusting for age, GFR, MDA, C-reactive protein, and hemoglobin A1C the difference in REE between the two groups persisted (adjusted difference 3.51 kcal/kg/d, 95% confidence interval 0.59 – 6.45, p = 0.020).
Conclusion
Patients with overt diabetic nephropathy who smoke have a higher REE, oxidative and inflammatory state. Elevated REE is not attributable to heightened oxidative stress and inflammatory state. Smoking is an independent risk factor for elevated REE in patients with diabetic nephropathy and provides an additional mechanism by which it may lead to poor outcomes.
doi:10.1186/1471-2369-6-13
PMCID: PMC1308817  PMID: 16303055
6.  Hypothyroidism attenuates protein tyrosine nitration, oxidative stress and renal damage induced by ischemia and reperfusion: effect unrelated to antioxidant enzymes activities 
BMC Nephrology  2005;6:12.
Background
It has been established that hypothyroidism protects rats against renal ischemia and reperfusion (IR) oxidative damage. However, it is not clear if hypothyroidism is able to prevent protein tyrosine nitration, an index of nitrosative stress, induced by IR or if antioxidant enzymes have involved in this protective effect. In this work it was explored if hypothyroidism is able to prevent the increase in nitrosative and oxidative stress induced by IR. In addition the activity of the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase was studied. Control and thyroidectomized (HTX) rats were studied 24 h of reperfusion after 60 min ischemia.
Methods
Male Wistar rats weighing 380 ± 22 g were subjected to surgical thyroidectomy. Rats were studied 15 days after surgery. Euthyroid sham-operated rats were used as controls (CT). Both groups of rats underwent a right kidney nephrectomy and suffered a 60 min left renal ischemia with 24 h of reperfusion. Rats were divided in four groups: CT, HTX, IR and HTX+IR. Rats were sacrificed and samples of plasma and kidney were obtained. Blood urea nitrogen (BUN) and creatinine were measured in blood plasma. Kidney damage was evaluated by histological analysis. Oxidative stress was measured by immunohistochemical localization of protein carbonyls and 4-hydroxy-2-nonenal modified proteins. The protein carbonyl content was measured using antibodies against dinitrophenol (DNP)-modified proteins. Nitrosative stress was measured by immunohistochemical analysis of 3-nitrotyrosine modified proteins. The activity of the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase was measured by spectrophotometric methods. Multiple comparisons were performed with ANOVA followed by Bonferroni t test.
Results
The histological damage and the rise in plasma creatinine and BUN induced by IR were significantly lower in HTX+IR group. The increase in protein carbonyls and in 3-nitrotyrosine and 4-hydroxy-2-nonenal modified proteins was prevented in HTX+IR group. IR-induced decrease in renal antioxidant enzymes was essentially not prevented by HTX in HTX+IR group.
Conclusion
Hypothyroidism was able to prevent not only oxidative but also nitrosative stress induced by IR. In addition, the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase seem not to play a protective role in this experimental model.
doi:10.1186/1471-2369-6-12
PMCID: PMC1291371  PMID: 16274486
7.  Barriers to successful care for chronic kidney disease 
BMC Nephrology  2005;6:11.
Background
The National Kidney Foundation has formulated clinical practice guidelines for patients with chronic kidney disease (K/DOQI). However, little is know about how many patients actually achieve these goals in a dedicated clinic for chronic kidney disease.
Methods
We performed a cross-sectional analysis of 198 patients with an estimated glomerular filtration rate of less than 30 ml/min/1.73 m2 and determined whether K/DOQI goals were met for calcium, phosphate, calcium-phosphate product, parathyroid hormone, albumin, bicarbonate, hemoglobin, lipids, and blood pressure.
Results
We found that only a small number of patients achieved K/DOQI targets. Recent referral to the nephrologist, failure to attend scheduled clinic appointments, African American ethnicity, diabetes, and advanced renal failure were significant predictors of low achievement of K/DOQI goals.
Conclusion
We conclude that raising awareness of chronic kidney disease and K/DOQI goals among primary care providers, early referral to a nephrologist, the exploration of socioeconomic barriers and cultural differences, and both patient and physician education are critical to improve CKD care in patients with Stage 4 and 5 CKD.
doi:10.1186/1471-2369-6-11
PMCID: PMC1283975  PMID: 16250919
8.  Cocaine-induced renal infarction: report of a case and review of the literature 
BMC Nephrology  2005;6:10.
Background
Cocaine abuse has been known to have detrimental effects on the cardiovascular system. Its toxicity has been associated with myocardial ischemia, cerebrovascular accidents and mesenteric ischemia. The pathophysiology of cocaine-related renal injury is multifactorial and involves renal hemodynamic changes, alterations in glomerular matrix synthesis, degradation and oxidative stress, and possibly induction of renal atherogenesis. Renal infarction as a result of cocaine exposure, however, is rarely reported in the literature.
Case presentation
A 48 year-old male presented with a four-day history of severe right flank pain following cocaine use. On presentation, he was tachycardic, febrile and had severe right costovertebral angle tenderness. He had significant proteinuria, leukocytosis and elevated serum creatinine and lactate dehydrogenase. Radiographic imaging studies as well as other screening tests for thromboembolic events, hypercoagulability states, collagen vascular diseases and lipid disorders were suggestive of Cocaine-Induced Renal Infarction (CIRI) by exclusion.
Conclusion
In a patient with a history of cocaine abuse presenting with fevers and flank pain suggestive of urinary tract infection or nephrolithiasis, cocaine-induced renal infarction must be considered in the differential diagnosis. In this article, we discuss the prior reported cases of CIRI and thoroughly review the literature available on this disorder. This is important for several reasons. First, it will allow us to discuss and elaborate on the mechanism of renal injury caused by cocaine. In addition, this review will demonstrate the importance of considering the diagnosis of CIRI in a patient with documented cocaine use and an atypical presentation of acute renal injury. Finally, we will emphasize the need for a consensus on optimal treatment of this disease, for which therapy is not yet standardized.
doi:10.1186/1471-2369-6-10
PMCID: PMC1253515  PMID: 16176587
9.  Case-control study on analgesics and nephropathy (SAN): protocol 
BMC Nephrology  2005;6:9.
Background
The association between intake of non-phenacetin-containing analgesics and the occurrence of chronic renal failure is still controversially discussed. A new epidemiologic study was planned and conducted in Germany and Austria.
Methods/design
The objective of the international, multicenter case-control study was to evaluate the association between end-stage renal disease (ESRD) and use of non-phenacetin-containing analgesics with particular emphasis on combined formulations. A targeted sample of 1000 new (incident) dialysis patients, aged less than 50 years, was planned to recruit between January 1, 2001 and December 31, 2004. The age limit was chosen to avoid contamination of the study population with phenacetin-containing analgesics to the extent possible. Four control subjects per ESRD case, matched by age, sex, and region were selected from the population living in the region the case came from.
Lifetime exposure to analgesics and potential renal risk factors were recorded in a single face-to-face interview. A set of aids was introduced to reinforce the memory of study participants.
A standardized, pre-tested interview questionnaire (participants), a medical documentation sheet (physicians in dialysis centres), a logbook for all activities (dialysis centres) were used to collect the necessary data.
Quality management consisted of the standardized procedures, (re-) training and supervision of interviewers, regular checks of all incoming data for completeness and plausibility.
The study is scientifically independent and governed by a international Scientific Advisory Committee that bridged the gap between the sponsoring companies and the investigators. Also other advisory groups assisted the managing committee of the study. All relevant German and Austrian nephrological associations supported the study, and the study design was carefully reviewed and approved by the Kidney Foundation of Germany.
Discussion
The study is expected to answer the main research question by end 2005. There is however a high potential for various biases that we tried to address with adequate measure. One limitation however cannot be overcome: The methodologically needed age-limitation of the study will make it not easy to generalize the results to age groups over 50 years. It might be suggested to repeat the study for persons over 50 years in 10 years when contamination with phenacetin use early in life is likely to be outgrown.
doi:10.1186/1471-2369-6-9
PMCID: PMC1198232  PMID: 16086834
10.  Progression of kidney disease in type 2 diabetes – beyond blood pressure control: an observational study 
BMC Nephrology  2005;6:8.
Background
The risk factors for progression of chronic kidney disease (CKD) in type 2 diabetes mellitus (DM) have not been fully elucidated. Although uncontrolled blood pressure (BP) is known to be deleterious, other factors may become more important once BP is treated.
Methods
All patients seen in the outpatient clinics of our hospital between January 1993 and September 2002 with type 2 DM and clinical evidence of CKD were evaluated. Progression of kidney disease was evaluated by rate of decline of glomerular filtration rate (GFR) as estimated from the simplified MDRD formula. Variables associated with progression in univariate analyses were examined by multivariate analysis to determine the factors independently associated with kidney disease progression.
Results
343 patients (mean age 69 years; all male; 77% Caucasian) were studied. Mean BP, glycated hemoglobin, and serum cholesterol during the study period were 138/72 mmHg, 8.1%, and 4.8 mmol/L, respectively. Mean decline of GFR was 4.5 ml min-1 1.73 m2-1 yr-1 (range -14 to +32). Low initial serum albumin (p < 0.001), black race (p < 0.001), and degree of proteinuria (p = 0.002), but not blood pressure, glycated hemoglobin, or serum cholesterol, were independently associated with progression.
Conclusion
In a cohort of diabetic patients with CKD in whom mean BP was < 140/80 mmHg, the potentially remediable factors hypoalbuminemia and proteinuria but not blood pressure were independently associated with progression of kidney disease. Further understanding of the relationship between these factors and kidney disease progression may lead to beneficial therapies in such patients.
doi:10.1186/1471-2369-6-8
PMCID: PMC1180831  PMID: 15985177
11.  Does treating obesity stabilize chronic kidney disease? 
BMC Nephrology  2005;6:7.
Background
Obesity is a growing health issue in the Western world. Obesity, as part of the metabolic syndrome adds to the morbidity and mortality. The incidence of diabetes and hypertension, two primary etiological factors for chronic renal failure, is significantly higher with obesity. We report a case with morbid obesity whose renal function was stabilized with aggressive management of his obesity.
Case report
A 43-year old morbidly obese Caucasian male was referred for evaluation of his chronic renal failure. He had been hypertensive with well controlled blood pressure with a body mass index of 46 and a baseline serum creatinine of 4.3 mg/dl (estimated glomerular filtration rate of 16 ml/min). He had failed all conservative attempts at weight reduction and hence was referred for a gastric by-pass surgery. Following the bariatric surgery he had approximately 90 lbs. weight loss over 8-months and his serum creatinine stabilized to 4.0 mg/dl.
Conclusion
Obesity appears to be an independent risk factor for renal failure. Targeting obesity is beneficial not only for better control of hypertension and diabetes, but also possibly helps stabilization of chronic kidney failure.
doi:10.1186/1471-2369-6-7
PMCID: PMC1181818  PMID: 15955257
12.  Effects of diabetes and hypertension on macrophage infiltration and matrix expansion in the rat kidney 
BMC Nephrology  2005;6:6.
Background
In experimental models of diabetes mellitus, aggravation of renal injury by concomitant hypertension has been described. Inflammatory mechanisms contribute to renal damage in both diseases. We investigated whether hypertension and diabetes mellitus act synergistically to induce macrophage infiltration and matrix expansion in the kidney.
Methods
Insulin-dependent diabetes mellitus was induced by streptozotocin injections to hypertensive mRen2-transgenic rats (TGR) and normotensive Sprague-Dawley control rats. Quantitative immunohistochemical examination of kidney tissue sections was used to measure macrophage infiltration and matrix expansion. The expression of MCP-1, Osteopontin, RANTES, ICAM-1 and VCAM-1 was evaluated by real-time RT-PCR. The localization of MCP-1 was studied by immunohistochemistry.
Results
Macrophage infiltration was present in the kidney of normotensive diabetic rats. Hypertensive rats exhibited a more marked infiltration of macrophages, regardless of whether diabetes was present or not. Gene expression of ICAM-1, VCAM-1 and RANTES was unaltered whereas Osteopontin and MCP-1 were induced by hypertension. Immunoreactive MCP-1 was slightly increased in diabetic rat kidney podocytes, and more markedly increased in hypertensive animals. Glomerular matrix accumulation was induced by diabetes and hypertension to a similar degree, and was highest in hypertensive, diabetic animals.
Conclusion
Diabetes mellitus caused a mild, and angiotensin-dependent hypertension a more marked infiltration of macrophages in the kidney. Combination of both diseases led to additive effects on matrix expansion but not on inflammation. Hypertension appears to be a much stronger stimulus for inflammation of the kidney than STZ diabetes, at least in mRen2-transgenic rats.
doi:10.1186/1471-2369-6-6
PMCID: PMC1175090  PMID: 15918915
13.  Comparison of two recombinant erythropoietin formulations in patients with anemia due to end-stage renal disease on hemodialysis: A parallel, randomized, double blind study 
BMC Nephrology  2005;6:5.
Background
Recombinant human erythropoietin (EPO) is used for the treatment of last stage renal anemia. A new EPO preparation was obtained in Cuba in order to make this treatment fully nationally available. The aim of this study was to compare the pharmacokinetic, pharmacodynamic and safety properties of two recombinant EPO formulations in patients with anemia due to end-stage renal disease on hemodialysis.
Methods
A parallel, randomized, double blind study was performed. A single 100 IU/Kg EPO dose was administered subcutaneously. Heberitro (Heber Biotec, Havana, formulation A), a newly developed product and Eprex (CILAG AG, Switzerland, formulation B), as reference treatment were compared. Thirty-four patients with anemia due to end-stage renal disease on hemodialysis were included. Patients had not received EPO previously. Serum EPO level was measured by enzyme immunoassay (EIA) during 120 hours after administration. Clinical and laboratory variables were determined as pharmacodynamic and safety criteria until 216 hours.
Results
Both groups of patients were similar regarding all demographic and baseline characteristics. EPO kinetics profiles were similar for both formulations; the pharmacokinetic parameters were very close (i.e., AUC: 4667 vs. 4918 mIU.h/mL; Cmax: 119.1 vs. 119.7 mIU/mL; Tmax: 13.9 vs. 18.1 h; half-life, 20.0 vs. 22.5 h for formulations A and B, respectively). The 90% confidence intervals for the ratio between both products regarding these metrics were close to the 0.8 – 1.25 range, considered necessary for bioequivalence. Differences did not reach 20% in any case and were not determined by a formulation effect, but probably by a patients' variability effect. Concerning pharmacodynamic features, a high similitude in reticulocyte counts increments until 216 hours and the percentage decrease in serum iron until 120 hours was observed. There were no differences between formulations regarding the adverse events and their intensity. The more frequent events were pain at injection site (35.3%) and hypertension (29%). Additionally, further treatment of the patients with the study product yielded satisfactory increases in hemoglobin and hematocrit values.
Conclusion
The formulations are comparable. The newly developed product should be acceptable for long-term application.
doi:10.1186/1471-2369-6-5
PMCID: PMC1164417  PMID: 15910687
14.  Time course study of oxidative and nitrosative stress and antioxidant enzymes in K2Cr2O7-induced nephrotoxicity 
BMC Nephrology  2005;6:4.
Background
Potassium dichromate (K2Cr2O7)-induced nephrotoxicity is associated with oxidative and nitrosative stress. In this study we investigated the relation between the time course of the oxidative and nitrosative stress with kidney damage and alterations in the following antioxidant enzymes: Cu, Zn superoxide dismutase (Cu, Zn-SOD), Mn-SOD, glutathione peroxidase (GPx), glutathione reductase (GR), and catalase (CAT).
Methods
Nephrotoxicity was induced in rats by a single injection of K2Cr2O7. Groups of animals were sacrificed on days 1,2,3,4,6,8,10, and 12. Nephrotoxicity was evaluated by histological studies and by measuring creatinine clearance, serum creatinine, blood urea nitrogen (BUN), and urinary excretion of N-acetyl-β-D-glucosaminidase (NAG) and total protein. Oxidative and nitrosative stress were measured by immunohistochemical localization of protein carbonyls and 3-nitrotyrosine, respectively. Cu, Zn-SOD, Mn-SOD, and CAT were studied by immunohistochemical localization. The activity of total SOD, CAT, GPx, and GR was also measured as well as serum and kidney content of chromium and urinary excretion of NO2 -/NO3-. Data were compared by two-way analysis of variance followed by a post hoc test.
Results
Serum and kidney chromium content increased reaching the highest value on day 1. Nephrotoxicity was made evident by the decrease in creatinine clearance (days 1–4) and by the increase in serum creatinine (days 1–4), BUN (days 1–6), urinary excretion of NAG (days 1–4), and total protein (day 1–6) and by the structural damage to the proximal tubules (days 1–6). Oxidative and nitrosative stress were clearly evident on days 1–8. Urinary excretion of NO2-/NO3- decreased on days 2–6. Mn-SOD and Cu, Zn-SOD, estimated by immunohistochemistry, and total SOD activity remained unchanged. Activity of GPx decreased on days 3–12 and those of GR and CAT on days 2–10. Similar findings were observed by immunohistochemistry of CAT.
Conclusion
These data show the association between oxidative and nitrosative stress with functional and structural renal damage induced by K2Cr2O7. Renal antioxidant enzymes were regulated differentially and were not closely associated with oxidative or nitrosative stress or with kidney damage. In addition, the decrease in the urinary excretion of NO2-/NO3- was associated with the renal nitrosative stress suggesting that nitric oxide was derived to the formation of reactive nitrogen species involved in protein nitration.
doi:10.1186/1471-2369-6-4
PMCID: PMC1142323  PMID: 15854231
15.  Surgical revascularization versus amputation for peripheral vascular disease in dialysis patients: a cohort study 
BMC Nephrology  2005;6:3.
Background
Surgical treatment of peripheral vascular disease (PVD) in dialysis patients is controversial.
Methods
We examined the post-operative morbidity and mortality of surgical revascularization or amputation for PVD in a retrospective analysis of United States Renal Data System. Propensity scores for undergoing amputation were derived from a multivariable logistic regression model of amputation.
Results
Of the Medicare patients initiated on dialysis from Jan 1, 1995 to Dec 31, 1999, patients underwent surgical revascularization (n = 1,896) or amputation (n = 2,046) in the first 6 months following initiation of dialysis were studied. In the logistic regression model, compared to claudication, presence of gangrene had a strong association with amputation [odds ratio (OR) 19.0, 95% CI (confidence interval) 13.86–25.95]. The odds of dying within 30 days and within1 year were higher (30 day OR: 1.85, 95% CI: 1.45–2.36; 1 yr OR: 1.46, 95% CI: 1.25–1.71) in the amputation group in logistic regression model adjusted for propensity scores and other baseline factors. Amputation was associated with increased odds of death in patients with low likelihood of amputation (< 33rd percentile of propensity score) and moderate likelihood of amputation (33rd to 66th percentile) but not in high likelihood group (>66th percentile). The number of hospital days in the amputation and revascularization groups was not different.
Conclusion
Amputation might be associated with higher mortality in dialysis patients. Where feasible, revascularization might be preferable over amputation in dialysis patients.
doi:10.1186/1471-2369-6-3
PMCID: PMC1079864  PMID: 15780133
16.  Antiglucocorticoid RU38486 reduces net protein catabolism in experimental acute renal failure 
BMC Nephrology  2005;6:2.
Background
In acute renal failure, a pronounced net protein catabolism occurs that has long been associated with corticoid action. By competitively blocking the glucocorticoid receptor with the potent antiglucocorticoid RU 38486, the present study addressed the question to what extent does corticoid action specific to uremia cause the observed muscle degradation, and does inhibition of glucocorticoid action reduce the protein wasting?
Methods
RU 38486 was administered in a dose of 50 mg/kg/24 h for 48 h after operation to fasted bilaterally nephrectomized (BNX) male adult Wistar rats and sham operated (SHAM) controls. Protein turnover was evaluated by high performance liquid chromatography (HPLC) of amino acid efflux in sera from isolated perfused hindquarters of animals treated with RU 38486 versus untreated controls.
Results
Administration of RU 38486 reduces the total amino acid efflux (TAAE) by 18.6% in SHAM and 15.6% in BNX and efflux of the indicator of net protein turnover, phenylalanine (Phe) by 33.3% in SHAM and 13% in BNX animals as compared to the equally operated, but untreated animals. However, the significantly higher protein degradation observed in BNX (0.6 ± 0.2 nmol/min/g muscle) versus SHAM (0.2 ± 0.1 nmol/min/g muscle) rats, as demonstrated by the marker of myofribrillar proteolytic rate, 3-Methylhistidine (3 MH) remains unaffected by administration of RU 38486 (0.5 ± 0.1 v. 0.2 ± 0.1 nmol/min/g muscle in BNX v. SHAM).
Conclusion
RU 38486 does not act on changes of muscular protein turnover specific to uremia but reduces the effect of stress- stimulated elevated corticosterone secretion arising from surgery and fasting. A potentially beneficial effect against stress- induced catabolism in severe illness can be postulated that merits further study.
doi:10.1186/1471-2369-6-2
PMCID: PMC550647  PMID: 15715918
17.  Polymorphisms of the insertion / deletion ACE and M235T AGT genes and hypertension: surprising new findings and meta-analysis of data 
BMC Nephrology  2005;6:1.
Background
Essential hypertension is a common, polygenic, complex disorder resulting from interaction of several genes with each other and with environmental factors such as obesity, dietary salt intake, and alcohol consumption. Since the underlying genetic pathways remain elusive, currently most studies focus on the genes coding for proteins that regulate blood pressure as their physiological role makes them prime suspects.
The present study examines how polymorphisms of the insertion/deletion (I/D) ACE and M235T AGT genes account for presence and severity of hypertension, and embeds the data in a meta-analysis of relevant studies.
Methods
The I/D polymorphisms of the ACE and M235T polymorphisms of the AGT genes were determined by RFLP (restriction fragment length polymorphism) and restriction analysis in 638 hypertensive patients and 720 normotensive local blood donors in Weisswasser, Germany. Severity of hypertension was estimated by the number of antihypertensive drugs used.
Results
No difference was observed in the allele frequencies and genotype distributions of ACE gene polymorphisms between the two groups, whereas AGT TT homozygotes were more frequent in controls (4.6% vs. 2.7%, P = .08). This became significant (p = 0.035) in women only. AGT TT genotype was associated with a 48% decrease in the risk of having hypertension (odds ratio: 0.52; 95% CI, 0.28 to 0.96), and this risk decreased more significantly in women (odds ratio: 0.28; 95% CI, 0.1 to 0.78). The meta-analysis showed a pooled odds ratio for hypertension of 1.21 (TT vs. MM, 95% CI: 1.11 to 1.32) in Caucasians. No correlation was found between severity of hypertension and a specific genotype.
Conclusion
The ACE I/D polymorphism does not contribute to the presence and severity of essential hypertension, while the AGT M235T TT genotype confers a significantly decreased risk for the development of hypertension in the population studied here. This contrasts to the findings of meta-analyses, whereby the T allele is associated with increased risk for hypertension.
doi:10.1186/1471-2369-6-1
PMCID: PMC546009  PMID: 15642127

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