Cyclooxygenase inhibition improves endothelium-dependent vasodilatation in patients with chronic renal failure.

BACKGROUND: Some studies have demonstrated beneficial effects of L-arginine as a substrate for nitric oxide synthesis, and diclofenac as an inhibitor of cyclooxygenase (COX)-derived vasoconstrictive agents on vascular responses in humans during several pathological conditions. The aim of the present study was to investigate the acute effects of L-arginine and diclofenac on endothelium-dependent vasodilatation (EDV) and endothelium-independent vasodilatation (EIDV) in patients with chronic renal failure (CRF). METHODS: Effects of L-arginine and diclofenac on EDV and EIDV were measured in 15 patients with CRF and in 15 healthy controls by means of forearm blood flow measurements with venous occlusion plethysmography during local intra-arterial infusions of methacholine (2 and 4 micro g/min evaluating EDV) and sodium nitroprusside (5 and 10 micro g/min evaluating EIDV). RESULTS: L-Arginine infusion increased methacholine-induced vasodilatation both in patients with CRF and healthy controls. Diclofenac infusion increased methacholine-induced vasodilatation only in patients with CRF. There was no significant change in nitroprusside-induced vasodilatation after L-arginine and diclofenac infusions both in patients with CRF and healthy controls. CONCLUSIONS: These results suggest that COX inhibition reduces the levels of a prostanoid-derived vasoconstrictive agent contributing to the impaired EDV in patients with CRF, while in this age group L-arginine improves EDV regardless of renal function.     

Impaired endothelium-dependent vasodilatation in uraemia.

BACKGROUND: Patients with chronic renal failure (CRF) have a substantially increased risk of cardiovascular death, the proposed mechanisms being arrhythmias (left ventricular hypertrophy) and accelerated atherosclerosis. The vascular endothelium protects against the development of atherosclerosis principally by releasing vasoactive substances such as nitric oxide (NO) and endothelium-derived hyperpolarizing factor. In CRF there is accumulation of endogenous inhibitors of NO synthesis. In this present study we assessed endothelium-dependent vasodilatation in patients with advanced uraemia. METHODS: Sixteen uraemic patients (pre-dialysis and continuous ambulatory peritoneal dialysis) and 18 controls were studied. Forearm plethysmography was used to measure forearm blood flow and the changes induced by carbachol (endothelium-dependent vasodilator) and sodium nitroprusside (SNP; endothelium-independent vasodilator). The order of drugs infused was randomized between subjects. Dose response curves were constructed for each agent and area under the curve (AUC) calculated (arbitrary units). RESULTS: Overall, vasodilatation to SNP and carbachol was similar between uraemic patients and controls. However, it became apparent that there was a marked order effect for the drugs infused, such that infusion of SNP as the first agent blunted the subsequent response to carbachol. When only those patients and controls who received carbachol followed by SNP were studied (10 in each group), the response to carbachol in uraemic patients was attenuated compared to controls: AUC (median(range)) for uraemic patients 529.0 (150.9-834.7) compared to AUC for controls 703.9 (583.5-1576.6); P=0. 028. Vasodilatation to SNP was, however, similar between groups: AUC for uraemic patients 1475.0 (857.8-4717.1) compared to AUC for controls 1328.1 (216.6-3311.4); P=0.545. CONCLUSIONS: This study has demonstrated a marked drug order effect not previously described for forearm plethysmography. When the order effect was taken into account, this study demonstrated reduced vasodilatation to carbachol in uraemic patients with a preserved response to SNP. This pattern indicates impaired endothelium-dependent vasodilatation in uraemic patients, a defect that may predispose this group to accelerated atherosclerosis.     

Chronic renal failure in India

In a series of 2028 patients with chronic renal failure, thediseases leading to renal failure, the presence or absence ofreversible factors and their nature, and the rate of declineof renal function of the most common conditions have been describedand analysed. Seven diseases: chronic interstitial nephritis(27.85%), diabetic nephropathy (26.76%), chronic glomerulonephritis(18.20%), benign nephrosclerosis (10.06%), chronic pyelonephritis(7.29%), focal glom erulosclerosis (3.20%), and autosomal dominantpoly cystic disease of the kidneys (2.07%), accounted for 95.43%of all the patients. These diseases were studied in greaterdetail and the results are presented here. It was found thatthere was a great variation in the rate of decline of renalfunction in the different groups, with chronic glomerulonephritisand focal glomerular sclerosis progressing most rapidly, diabeticnephro pathy slightly slower, and the others at a less alarmingpace. However, once serum creatinine had reached 177 µmol/lthere was an inexorable decline in renal function and the endstage was reached in almost all patients.     

Endothelin in chronic renal failure.

The aims of the present study were to determine plasma endothelin (ET) in chronically uraemic patients, the renal clearance of endogenous ET in normal dog and man, and the effect of acute volaemic expansion on ET. The mean plasma ET concentration in haemodialysis patients was 57.5 +/- 5 pg/ml before haemodialysis and remained unchanged at 52.5 +/- 5 pg/ml after haemodialysis. They were thus significantly elevated both before and after haemodialysis (P less than 0.01) compared with plasma ET in normal subjects of 20.8 +/- 0.8 pg/ml. There was no evidence of ET clearance across the cuprophane membrane of the dialyser. Resting plasma ET values in the 15 non-dialysed uraemic patients ranged between 20 and 52.5 pg/ml (mean 38.2 +/- 2.3 pg/ml), significantly greater than those observed in controls (P less than 0.01). In CAPD patients, plasma ET was also significantly (P less than 0.01), elevated (63 +/- 10 pg/ml) when compared to controls, and similar to those observed in patients before haemodialysis. In dogs, mean ET did not diminish between the aorta and the renal vein (28.1 +/- 1 versus 28.4 +/- 2 pg/ml). In man mean ET did not significantly decline between the renal artery and the renal vein (17 +/- 3 to 13 +/- 0.8 pg/ml). In the seven healthy subjects who received 2000 ml of isotonic saline intravenously ET remained unchanged (24 +/- 2; 23 +/- 1 and 23 +/- 2 pg/ml before and 1 and 2 h after starting hydration respectively). We have thus shown that plasma ET is elevated in patients with chronic renal failure especially those on dialysis and CAPD.(ABSTRACT TRUNCATED AT 250 WORDS)     

Back pain in chronic renal failure.

Back pain in chronic renal failure Patient SK, a 40-yr-old female, resident of Bhagalpur villagein Bihar, India, was operated for gallstones 3 years previously.On pre-operative checkup, mild renal dysfunction was detected.She was asymptomatic for renal disease with serum creatinineof 159 µmol/l (1.8 mg/dl), bland urinary sediment     

Kinetics of carbamylated haemoglobin in acute renal failure.

BACKGROUND: Carbamylation of proteins by isocyanic acid, the reactive form of cyanate derived from urea, is increased in uraemia and may contribute to uraemic toxicity. Kinetics of carbamylation that may reflect uraemic toxicity is not clearly defined in acute renal failure (ARF). METHODS: Twenty-eight patients with ARF and 13 with chronic renal failure (CRF) were included in the study in order to determine changes in carbamylated haemoglobin concentration (CarHb) in ARF. The usefulness of this parameter for differentiating ARF from CRF was also investigated. CarHb was measured by high-performance liquid chromatography after acid hydrolysis. RESULTS: Mean CarHb level (expressed as microg carbamyl valine per gram (CV/g) Hb) was significantly higher in ARF (54.3+/-5.2) than in normal subjects (31.6+/-1.3). On admission, CarHb level was correlated with duration of ARF prior to hospitalization in the intensive care unit (r(2)=0.723, P<0.001). CarHb was significantly higher at recovery in the subgroup of patients requiring haemodialysis than in the subgroup not requiring haemodialysis (82. 4+/-11.3 vs 46.7+/-5.2, P<0.01). Similarly dialysis patients lost more weight (8.6+/-1.4 vs 2.7+/-0.5 kg, P<0.005) and had higher averaged blood urea levels in the 20 days prior to recovery (17. 6+/-1.9 vs 11.3+/-1.8 mol/l, P<0.05). After recovery, CarHb level decreased at a rate of 0.219 microg CV/g Hb per day in patients with reversible renal insufficiency. CarHb concentration was higher in patients with CRF. A cut-off CarHb value of 100 microg CV/g Hb had a sensitivity of 94% and a positive predictive value of 94% for differentiating ARF from CRF. CONCLUSIONS: Kinetics of CarHb showed a near normal red blood cell life span in ARF. Changes in CarHb enabled, with a good sensitivity, the distinction to be made between patients who recovered from ARF and those with sustained renal impairment, whether due to prior CRF or resulting from parenchymal sequelae. Measurement of CarHb is valuable at clinical presentation of ARF in patients with an unknown medical history of renal disease.     

Endothelial dysfunction in chronic renal failure: roles of lipoprotein oxidation and pro-inflammatory cytokines.

BACKGROUND: Chronic renal failure (CRF) is associated with an increased risk of ischaemic heart disease (IHD), but the mechanisms responsible are controversial. We investigated the relationship of two sets of candidate mechanisms-indices of LDL oxidation and markers of inflammatory activity-with vascular endothelial dysfunction (VED). METHODS: We carried out cross-sectional analysis of 23 dialysed and 16 non-dialysed CRF patients, 28 healthy controls, and 20 patients with stable angina and normal renal function. The following were determined: (i) LDL oxidation by Cu(2+) and ultraviolet light, serum autoantibodies to oxidized LDL (oxLDL); (ii) forearm flow-mediated vasodilatation, plasma concentrations of adhesion molecules, and von Willebrand factor (vWF); and (iii) circulating levels of TNF-alpha and IL-6, C-reactive protein (CRP), and fibrinogen. RESULTS: Endothelium-dependent vasodilatation (EDV) was lower in angina, pre-dialysis, and dialysis CRF patients than in controls (all P<0.005). Compared with controls, vWf (P<0.005) and adhesion molecules (vCAM-1, P<0.005; iCAM-1, P=0.01; E-selectin, P=0.05) were raised in dialysis, and vCAM-1 (P=0.01) in pre-dialysis CRF patients. Dialysed patients had lower HDL cholesterol (P=0.01) and higher triglyceride (P=0.05) than controls, but LDL-oxidation was similar in all groups. Autoantibodies to oxLDL were raised in angina (P<0.005) and pre-dialysis (P=0.006), but were absent in most dialysed patients. Concentrations of IL-6, TNF-alpha, CRP and fibrinogen were elevated in CRF compared with control and angina patients (P<0.005). In the whole population, IL-6 and TNF-alpha correlated negatively with EDV, HDL cholesterol, and positively with triglyceride, blood pressure, vWf, iCAM-1, vCAM-1 and E-selectin (r=-0.43 to +0.70, all P<0.05). CONCLUSIONS: Endothelial dysfunction is unrelated to LDL oxidation, suggesting that LDL oxidation might not be a major cause of VED in CRF. In contrast VED was more severe in CRF than in angina patients and is associated with increased acute-phase proteins and plasma cytokines, demonstrating a chronic inflammatory state. These observations may explain the VED and increased IHD risk of patients with CRF.     

Chronic administration of sildenafil improves erectile function in a rat model of chronic renal failure

The relationship between erectile dysfunction (ED) and chronic renal failure (CRF) has been reported in several studies. This study aimed to investigate whether the chronic use of sildenafil could enhance the erectile capacity in CRF-induced rats. In addition, we assessed the effect of that treatment on certain molecules, which have been suggested to play crucial roles in erectile physiology and CRF-related ED as well. Three groups of animals were utilized: (1) age-matched control rats, (2) CRF-induced rats, (3) CRF-induced rats treated with chronic administration of sildenafil (5 mg kg⁻¹ p.o. for 6 weeks [treatment started after 6 weeks of CRF induction]). At 3 months, all animals underwent cavernosal nerve stimulation (CNS) to assess erectile function. Penile tissue advanced glycation end products (AGE''s)/5-hydroxymethyl-2-furaldehyde, malondialdehyde (MDA), cGMP (ELISA), inducible nitric oxide synthase (iNOS) and neuronal NOS (nNOS) (Western blot) analyses were performed in all rat groups. CRF-induced rats had a significant decrease in erectile function when compared to control rats (P < 0.05). The increase in both intracavernosal pressure (ICP) and area under the curve of CRF-induced rats treated with sildenafil (Group 3) was greater than CRF-induced rats (Group 2). Additionally, sildenafil treatment decreased AGE, MDA and iNOS levels, while it preserved nNOS and cGMP contents in CRF-induced penile tissue. Decreased AGE, MDA, iNOS and increased nNOS, cGMP levels at the sildenafil-treated group increased both ICP and Total ICP to CNS, which led to improve erectile function in CRF-induced rats. The results of the present study revealed the therapeutic effect of chronic sildenafil administration on erectile function in CRF-induced rats.     

The safety of gadolinium in patients with stage 3 and 4 renal failure.

BACKGROUND: Although there is a well-documented risk of acute renal failure (ARF) with the iodinated contrast agents, intravenous gadolinium-based contrast agents are considered non-nephrotoxic and have been widely used for magnetic resonance imaging (MRI). However, debate continues regarding the safety issue of gadolinium, especially in patients with kidney failure. Therefore, we aimed to evaluate the safety of gadolinium in patients with stage 3 and 4 renal failure as well as risk factors for nephrotoxicity. METHOD: We retrospectively analysed 473 patients with chronic renal failure who underwent angiographic MRI procedures in our centre from February 1999 to March 2005 in whom gadolinium was used as the sole contrast agent at a dose of 0.2 ml/kg. Among them, 91 patients with stage 3 or 4 renal failure according to K/DOQI definition, who had available data in their files, were enrolled in the study. The ARF was defined as an increase of at least 0.5 mg/dl in serum creatinine level over baseline after using gadolinium. RESULTS: Eleven of 91 (52 males, 39 females; median age 59 years; median estimated glomerular filtration rate (eGFR) 33 ml/min/1.73 m2) patients developed ARF (12.1%). The median eGFR was lower in patients with ARF than in those who did not develop ARF. The risk factors for ARF were baseline eGFR, older age, diabetic nephropathy and low baseline haemoglobin and albumin levels. Baseline eGFR and diabetic nephropathy were determined as the independent risk factors in regression analysis. CONCLUSIONS: An ARF can occur after gadolinium-based contrast agents in patients with moderate to severe chronic renal failure. Risk factors for ARF after gadolinium toxicity include diabetic nephropathy and low GFR.     

High incidence of renal failure in patients with aortic aneurysms.

BACKGROUND: Renal failure (RF) is a well-recognized complication of aortic aneurysms (AA) although its incidence has been poorly documented previously. The purpose of this study is to examine the incidence of RF in patients with AA and prognosis of AA patients with RF. METHODS: Renal function, complications and prognosis of AA patients with RF were retrospectively reviewed in 350 AA patients (median age 69.8+/-10.7 years) in the International Medical Center of Japan from 1989 to 1999. RESULTS: Among 350 patients with AA, 90 patients (25.7%) had chronic renal failure (CRF) at the initiation of follow-up. The number of CRF patients increased to 117 (33.4%) at 30 months of follow-up. Forty-four out of 160 patients (27.5%) who had aortic surgery developed postoperative acute renal failure (ARF). Stepwise logistic regression analysis revealed that age (>or=65 years), hypertension and multiple aneurysms were independent risk factors for CRF, whereas dissecting aneurysms, preoperative serum creatinine (sCr) levels and duration of surgery were independent risk factors for postoperative ARF in AA patients. In the 5-year follow-up of AA patients with CRF, the mean slopes of 1/serum-creatinine did not significantly differ between conservative treatment and surgical treatment. The survival rates were 49.5% in the conservative treatment group and 67.3% in the surgical treatment group. CONCLUSION: Our data suggest that the management of renal function including blood pressure from an early stage in AA patients is important since CRF is highly prevalent in AA patients and affects their prognosis and mortality.     

The deceiving image: asymptomatic renal malakoplakia in a patient with chronic renal failure.

The diagnosis of tumour-like renal lesions may be difficultin chronic renal failure (CRF) patients. We present a patient with severe CRF, in whom the diagnosisof malakoplakia during intervention avoided nephrectomy, therebypreserving his residual renal     

Prevalence of chronic renal failure in adults in Delhi, India.

BACKGROUND: Chronic renal failure (CRF) is a debilitating condition responsible for high morbidity and mortality and is a financial burden on government and society. Because of its costs and the complexity of its treatment, proper care is available to very few patients in India. A community-based study has not been done to determine the prevalence of CRF in India. METHODS: We used a multi-stage cluster sampling method in the South Zones of Delhi. In each area, we first contacted the local social leader and explained the study and the medical information pamphlets. On pre-scheduled days, the study team canvassed the study zone. The individuals contacted responded to a detailed questionnaire, and had a physical examination, a dipstick urine test for albumin and sugar and a blood test for serum creatinine. A serum creatinine >1.8 mg% defined renal failure. A repeat test for serum creatinine was done after 8-12 weeks to confirm chronicity of renal failure. If it was >1.8 mg% after 3 months in the absence of reversible factors, CRF was diagnosed. The person found to have CRF was asked to attend a hospital renal clinic for further investigations and individualized management. RESULTS: A total of 4972 persons were contacted for the study. Their mean age was 42+/-13 years; 56% were males. Out of the 4972 who were initially approached, 4712 agreed to give the blood sample, and thus were included for the evaluation of CRF. CRF was found in 37 of them. Thus, the prevalence of CRF in that adult population was 0.785% or 7852/million. CONCLUSIONS: The prevalence of CRF in India makes it a serious problem in need of urgent efforts to contain it.     

Effects of erythropoietin, bromocryptine and hydralazine on testicular function in rats with chronic renal failure

Summary. We evaluated the effects of chronic renal failure (CRF) on testicular function and semen physiology. A CRF model was created in 48 male rats by performance of five-sixths nephrec-tomies in two-stage procedures, and a control (group A) by two-stage sham operation on six male rats. Seven weeks later, serum urea and creatinine concentrations were assessed, and the nephrectomized rats were then equally divided into four groups, B, C, D and E, and treated with saline, erythropoietin, bromocryptine and hydralazine, respectively. Seventeen weeks after the first surgical procedure, the number of fertile rats, the mean values of epididymal sperm content and motility, the outcome of in vitro fertilization, and peripheral serum testosterone concentrations and responses to human chorionic gonadotropin were significantly higher ( P <0.05) in groups A, G and D than in groups B and E. Serum prolactin concentration was significantly higher ( P <0.05) in all groups of nephrectomized rats than in group A. Our results indicate that bromocryptine and erythropoetin improve Leydig cell function, sper-matogenesis, epididymal sperm maturation, and sperm fertilizing capacity in rats with CRF.     

Design of human trials in progressive renal failure

Summary: Future studies aimed at testing therapies to prevent progression of renal failure have much to learn from the past successful and unsuccessful attempts. Given the insensitivity of all other methods, the proper index of renal function for study of progression of renal failure should be radioisotope glomerular filtration marker clearance. Randomized prospective controlled studies are required, and statistical analysis should be designed to allow consideration for patient drop out and covariants. Since compensatory mechanisms come into place as soon as there is any nephron damage, more attention should be paid to studying the progression of renal failure from a normal glomerular filtration rate (GFR) until there is an elevated plasma creatinine level. This suggestion is supported by four under-lying concepts: (i) overall GFR does not fall until about 23% of nephrons are destroyed; (ii) if progression is multifactorial, the later in the progress the more likely that more factors are present to confound issues; (iii) this may allow study of greater patient numbers, since patients who have had renal biopsy or ultrasound diagnosis can be entered before the plasma creatinine is abnormal; (iv) in early stages of disease, issues of concurrent treatment may be less difficult (e.g. diet, phosphate control, hypertension). With diabetes, prognosis and progression has been related to proteinuria. In non-diabetic disease proteinuria has been related to progression, but the effect of alleviation of proteinuria on prognosis has not been intensively studied. There is a need to study the relationships between proteinuria and progression, particularly in early renal disease. At present most therapies are based upon observations in the partially ablated rat model. Other animal models should be developed, and the details of early mechanisms in the rat further clarified. Since we believe progression is likely to be multifactorial in pathogenesis, combination therapies may be required to optimally reduce progression.     

Colchicine myoneuropathy in chronic renal failure patients with gout

Colchicine myoneuropathy is a rare and often underdiagnosed disease. It often presents as painless subacute muscle weakness. We present a case of painful colchicine myoneuropathy in a 76-year-old man with chronic renal failure and gout. Published work about clinical presentations of colchicine myoneuropathy in gouty arthritis patients are reviewed. During the previous year, the patient had a drug regimen of colchicine 0.5 mg three times per day for a 3 day course each month. He developed bilateral lower leg weakness and severe myalgia. His serum creatinine level was 680.7 micromol/L and creatinine kinase was 959 IU/L on admission. Laboratory findings included decreasing amplitude of motor and sensory nerve conduction velocity and an electromyogram showed small amplitude, short duration polyphasic waves over the right biceps. A muscle biopsy disclosed vacuolar changes in the cytoplasm. These results all supported a diagnosis of colchicine myoneuropathy. After cessation of colchicine, the creatinine kinase level decreased approximately 50% in 6 days, myalgia subsided and his muscle weakness improved gradually over the next 2 weeks.     

Natural history of chronic renal failure: a reappraisal.

In this retrospective study we have analysed the rate of progression of renal insufficiency, ascertained from the slopes of the plot of inverse serum creatinine against time, of 102 patients with moderate to severe chronic renal failure (CRF). We have applied 'breakpoint' analysis of the slopes to identify changes in the rate of progression and attempted to determine the factors associated with these changes. Seventy-one patients were found to have progressive CRF, while the remaining 31 had stable or improving renal function. Of the parameters studied, using weighted least-squares analysis, proteinuria was the most significant predictor of progression (regression coefficient: -0.1775, P = 0.0075, adjusted r2 = 0.1059). A positive correlation was observed between proteinuria and diastolic blood pressure (DBP) (r = 0.336, P = 0.0054). Once the predictive value of proteinuria was taken into account, there was no difference in the progression rate between diagnostic groups, other than those patients with polycystic kidney disease who had a significantly faster rate of progression (P = 0.0037). In 49 patients, there was at least one change in the rate of progression with time. There was an inverse correlation between change in slope and a change in DBP (r = -0.352, P = 0.003). We conclude that changes in DBP are often associated with the frequent changes in the rate of progression of CRF. However, a causal link could not be established as in a large number of cases the two changes appeared to occur simultaneously in the absence of changes in antihypertensive therapy.