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Functional and morphologic maturation of the superficial nephrons. Relationship to total kidney function.

The functional and morphologic pattern of superficial nephron development was studied in guinea pigs ranging in age between 2 h and 38 days. Concomitent measurements of total kidney function and glomerular counts were also performed. Superficial nephron glomerular filtration rate was found to increase from 0.92 to 19.32 nl/min. The filtration rate of the entire kidney rose from 0.19 to 1.31 ml/min. During the first 15 days of life the average rate of increase in glomerular filtration rate per nephron (0.48 nl/min.day), obtained by dividing the increase in total kidney glomerular filtration rate by glomerular number, was more than twice the observed rate of increase in the superficial nephrons (0.21 nl/min.day). During the remainder of the first month, the increase in superficial nephron glomerular filtration rate (0.97 nl/min.day) was greater than the average increase for all nephrons (0.71 nl/min.day). Thus, the initial increase in total kidney glomerular filtration rate was primarily a consequence of the activity of the deep nephrons, whereas during the ensuing period the superficial nephrons appeared to be the sole contributors to the change in total kidney glomerular filtration rate.The increase in superficial nephron glomerular filtration rate was found to correlate closely with the increase in proximal tubular length. Functional glomerulotubular balance was maintained throughout the entire period of renal maturation.

Aging↗

Percutaneous transluminal renal angioplasty in the patient with a solitary functioning kidney.

Since the introduction of percutaneous transluminal renal angioplasty, it has become established as an effective treatment for the correction of renovascular hypertension or the preservation of renal function. However, there has been a general reluctance to use it or other interventional procedures in any patient with a solitary functioning kidney. We attempted renal angioplasty in 11 patients each of whom had a solitary functioning kidney. All 11 had had either a previous contralateral nephrectomy or an autonephrectomy from chronic arterial occlusion. The patients ranged in age from 42 to 81 years. In nine of the 11 patients, a catheter was negotiated across the stenosis, and the lesion was dilated successfully. In two, the lesion could not be crossed. In the group of nine patients whose lesions were dilated successfully, clinical follow-up (2-180 weeks) revealed that hypertension was cured in four and improved in five. Of the two patients in whom angioplasty was not possible, one required emergency renal bypass surgery and the other had no change in renal status. Renal function test results after the procedure were variable and did not correlate with decreases in blood pressure. We conclude that percutaneous renal angioplasty is a satisfactory alternative to surgery for the treatment of renovascular hypertension or the preservation of renal function in a patient with a solitary functioning kidney.

Adult↗

Level of kidney function as a risk factor for atherosclerotic cardiovascular outcomes in the community.

OBJECTIVES: The goal of this study was to determine whether the level of kidney function is an independent risk factor for atherosclerotic cardiovascular disease (ASCVD) outcomes in the Atherosclerosis Risk in Communities (ARIC) study, a prospective cohort study of subjects aged 45 to 64 years. BACKGROUND: The level of kidney function is now recognized as a risk factor for ASCVD outcomes in patients at high risk for ASCVD, but it remains unknown whether the level of kidney function is a risk factor for ASCVD outcomes in the community. METHODS: Cox proportional-hazards regression was used to evaluate the association of glomerular filtration rate (GFR) with ASCVD after adjustment for the major ASCVD risk factors in 15,350 subjects. We searched for nonlinear relationships between GFR and ASCVD. RESULTS: During a mean follow-up time of 6.2 years, 965 (6.3%) of subjects had ASCVD events. Subjects with GFR of 15 to 59 ml/min/1.73 m(2) (n = 444, hazard ratio 1.38 [1.02, 1.87]) and 60 to 89 ml/min/1.73 m(2) (n = 7,665, hazard ratio 1.16 [1.00, 1.34]) had an increased adjusted risk of ASCVD compared with subjects with GFR of 90 to 150 ml/min/1.73 m(2). Each 10 ml/min/1.73 m(2) lower GFR was associated with an adjusted hazard ratio of 1.05 (1.02, 1.09), 1.07 (1.01, 1.12), and 1.06 (0.99, 1.13) for ASCVD, de novo ASCVD, and recurrent ASCVD, respectively. A nonlinear model did not fit the data better than a linear model. CONCLUSIONS: The level of GFR is an independent risk factor for ASCVD and de novo ASCVD in the ARIC study.

Arteriosclerosis↗

Rabbit kidney function in vitro: the effect of colloids, energy substrate, a vasodilator, perfusion pressure, and bovine serum albumin.

An in vitro perfusion system at 37 degrees C for the assessment of rabbit kidney function is described. The purpose of this assay system is to evaluate the effects of cryobiological manipulation on kidney function. The effect of the colloids dextran (MW = 70,000, 80,000, and 180,000) in the perfusate at 110 mm Hg were compared to a reduced perfusion pressure, colloid-free perfusate. Better function was obtained at lower perfusion pressure with the colloid-free perfusate. Less damage was noted histologically on light and electron microscopy. Investigation of energy substrates on rabbit kidney function demonstrated that butyrate, or lactate, in addition to glucose resulted in increased sodium and glucose reabsorption over glucose alone. Substrate-free perfused kidneys exhibited depressed Na transport. Lactate, and to some extent butyrate, decreased net glucose utilization. An alpha-adrenergic blocking agent, isoxsuprine, in the initial flush solution did not appear to be beneficial. An increase of perfusion pressure from 50 to 75 mm Hg resulted in an increase in GFR. Tubular function was enhanced by inclusion of small amounts of BSA in the perfusate.

Animals↗

Kidney function in domestic fowl with chronic occlusion of the ureter and caudal renal vein.

A previously published technique for producing renal insufficiency in chicks involves ligating the caudal renal vein together with the ureter near the midpoint of the kidney. This ligation occludes the normal route (caudal renal vein) by which blood exits the medial and posterior kidney divisions. The present study was conducted to evaluate kidney function following chronic caudal renal vein and ureter occlusion. The ureters and caudal renal veins of 2 to 3-week-old chicks were clamped with hemostatic clips (Clamp Group), and kidney function evaluations were conducted when the birds reached 14 weeks of age. Plasma values [osmolality, Na, K, Ca, inorganic P (Pi)] of control, sham, and clamp groups did not differ significantly. Plasma uric acid concentrations did not differ when the control and clamp groups were compared. Clamping the ureter near the midpoint of the kidney caused a significant reduction in the number of filtering glomeruli per kidney, but due to compensatory hypertrophy the kidney weights of the groups did not differ significantly. Kidney function comparisons (urine flow rates, glomerular filtration rates, renal plasma flow rates, urine pH, fractional excretion of Na, K, Ca, Pi, and uric acid) revealed a significant reduction in Na and K excretion by the clamp group, but other renal function parameters did not differ significantly. These experiments demonstrate that chickens have a remarkable capacity to survive significant reductions in renal mass and to adapt to major disruptions of blood flow patterns.

Animals↗

Severe hypoglycemia in type I diabetic patients with impaired kidney function.

OBJECTIVE: To assess the frequency and possible risk indicators of severe hypoglycemia in insulin-dependent (type I) diabetic patients with impaired kidney function. RESEARCH DESIGN AND METHODS: Retrospective follow-up examination of case subjects and control subjects with mean follow-up periods of 2.9 and 1.3 yr, respectively. The setting was the diabetes center at the Düsseldorf University hospital. Subjects were consecutive type I diabetic patients. Case subjects consisted of 44 patients with initial serum creatinine levels of greater than or equal to 133 microM and pathological proteinuria. Control subjects consisted of 46 patients with normal serum creatinine levels matched for age, duration of diabetes, and hypertension; 57% of case subjects and 67% of control subjects were being treated with beta-blockers. Incidence of severe hypoglycemia (cases/patient-yr) was assessed through an interviewer-administered questionnaire. RESULTS: At comparable levels of HbA1c (7.9 +/- 1.8 vs. 7.6 +/- 1.1%), case subjects had a fivefold higher incidence of severe hypoglycemic episodes (1.28 vs. 0.25 cases/patient-yr, P less than 0.02) than control subjects. Within the group with impaired kidney function, patients with severe hypoglycemic episodes had lower HbA1c levels (7.4 +/- 1.6 vs. 8.7 +/- 2.0%, P less than 0.03) and a lower body mass index (22.0 +/- 3.4 vs. 24.4 +/- 3.8 kg/m2, P less than 0.04) than those without severe hypoglycemic episodes, whereas serum creatinine levels, body weight-related insulin dosage (U x kg-1 x day-1), prevalence of blindness, autonomic neuropathy, and treatment with beta-blockers were comparable. CONCLUSIONS: Type I diabetic patients with impaired kidney function are at an excessively high risk of severe hypoglycemia. In addition to low HbA1c levels, a low body mass index appears to be a risk indicator for this adverse effect of insulin therapy.

Adult↗

Lansoprazole pharmacokinetics in subjects with various degrees of kidney function.

The pharmacokinetics of lansoprazole, a new benzimidazole proton pump inhibitor, was evaluated after multiple-dose oral administration to 20 subjects with various degrees of kidney function. Multiple blood samples were obtained after doses 1 and 7 of the once-daily seven-dose regimen, and plasma concentrations of lansoprazole and five metabolites were quantitated with use of HPLC. The free fraction of lansoprazole increased as kidney function declined. A significant, although weak, relationship existed between creatinine clearance (CLCR) and area under the plasma concentration versus time curve (AUC) and terminal disposition half-life (t1/2), calculated with total concentration data. Those individuals with lower CLCR values also had lower total AUC and t1/2 values. However, there was no statistically significant relationship between CLCR and peak plasma concentration or AUC, calculated with unbound concentration data. No adjustment of lansoprazole dose is recommended on the basis of impaired kidney function.

2-Pyridinylmethylsulfinylbenzimidazoles↗

Endogenous pancreatic polypeptide in different vascular beds: relationship to release and degradation in subjects with normal and decreased kidney function.

The plasma concentration of pancreatic polypeptide (PP-like immunoreactivity) was measured in different vascular beds in order to determine regional kinetics of endogenous PP in fasting, supine subjects with normal or moderately decreased kidney function. Patients with kidney disease (n = 10) had a significantly higher level of circulating PP than controls (n = 10): median PP = 52 (range 21 to 352) v 20 (6 to 143) pmol/L, respectively (P less than 0.02). Circulating PP was inversely correlated to 51Cr-EDTA plasma clearance (r = -0.57, P less than 0.02, n = 14) and directly correlated to serum creatinine concentration (r = 0.70, P less than 0.01). Hepatic venous PP was significantly higher than systemic PP in both controls and patients with kidney disease (P less than 0.001, n = 15). The values were positively correlated (r = 0.98, P less than 0.001; slope = 1.37 +/- 0.05, P less than 0.001), indicating a progressively increasing rate of PP secretion in subjects with raised circulating PP. No statistically significant difference could be detected between systemic and renal venous PP or across the lung, left adrenal gland, or lower limb. Assuming steady state between secretion and biodegradation, the metabolic clearance rate of the peptide was estimated to be approximately 600 to 800 mL/min in controls and slightly below this value in patients with nephropathy. These results suggest that the raised circulating PP found in patients with decreased kidney function is due to both increased secretion and decreased degradation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Endovascular revascularization of renal artery stenosis in the solitary functioning kidney.

The treatment of renal artery stenosis by angioplasty and stenting is an effective and accepted alternative to surgery for the treatment of renovascular hypertension and preservation of renal function. We report the technical and clinical outcomes of renal artery stenting in patients with a solitary functioning kidney and renal artery stenosis. From October 1993 to November 1999, 30 stents were placed in the renal arteries of 27 patients (mean age 72+/-8 years) with a solitary functioning kidney and azotemia. The mean diameter renal artery stenosis was 86+/-14%. The mean preprocedure serum creatinine (Cr) level was 3.0+/-1.5 mg/dL (range 1.5-7.5 mg/dL), arterial blood pressure was 171+/-29/85+/-13 mmHg, and the number of antihypertensive drugs was 2.9+/-1.1. Indications for stenting were suboptimal balloon dilation (n = 16), intimal dissection (n = 6), and restenosis following angioplasty (n = 5). Atherosclerotic ostial lesions were present in 25 (93%) of 27 renal arteries. This represents the largest series of renal artery stenting in patients with a solitary functioning kidney, and demonstrates this treatment modality to be a relatively safe alternative to conventional surgery in this high-risk patient group. Most (74%) of the patients in this series had improved or stabilized renal function. Further efforts to define preprocedural indicators of success are necessary to identify the patients who may benefit from revascularization of their solitary kidney.

Aged↗

[The use of dynamic renal scintigraphy for studying kidney functional disorders in patients with different forms of hypercorticism].

Results are submitted of studying the function of the kidneys in 34 patients with Itsenko [correction of Icenko]-Cushing disease and syndrome, who were evaluated by dynamic renoscintigraphy besides routine clinical procedures. Dynamic renoscintigraphy was found to be an important diagnostic acid enabling one to disclose function disorders of the kidneys in the preclinical stage under normal routine investigations. In this setting, there have been revealed disturbances both in secretory-filtrational and excretory and aggregate functions of the kidneys practically in all the patients irrespective of the type of hypercorticoidism. Surgical treatment of hypercorticoidism does not lead to normalization of the function of the kidneys. And what is more, function disorders of the kidney on the side of the surgical intervention appear to be even more serious.

Adrenocortical Hyperfunction↗

Effect of isolated cholaemia on systemic haemodynamics and kidney function in conscious dogs.

1. Systemic haemodynamics and kidney function were studied in the same dogs before and 14 days after choledochocaval anastomosis. 2. All dogs became deeply jaundiced whereas parenchymal liver function remained unchanged as assessed biochemically. 3. After choledochocaval anastomosis there was a decrease in mean arterial pressure (118 +/- 18 to 98 +/- 13 mmHg, P less than 0.005), and total peripheral resistance (4073.8 +/- 620.0 to 3327.6 +/- 244.9 kPa 1-1 s kg, P less than 0.01), whereas mean cardiac index and plasma volume corrected for body weight did not change. 4. Despite their disturbed systemic haemodynamics the cholaemic dogs and normal mean glomerular filtration rate and renal plasma flow. Maximal ability to concentrate and dilute the urine was, however, impaired during cholaemia. 5. It is concluded that cholaemia per se causes peripheral vasodilatation, hypotension and renal tubular dysfunction. Similar phenomena in jaundiced patients may contribute to their susceptibility to postoperative shock and acute renal failure.

Animals↗

Dietary citrate and kidney function affect aluminum, zinc and iron utilization in rats.

Four studies were conducted to examine the effect of dietary citrate and calcium and modest reductions in kidney function on aluminum utilization in rats. Ingestion of citrate increased retention of aluminum in bones of rats fed 1 mg Al/g diet and increased apparent absorption of zinc. The increased retention of aluminum was not linearly related to dietary citrate levels. These data suggest that citrate had a general effect on the solubility of trace elements in the gut that promoted absorption. When dietary calcium intake was increased from 67 to 250 mumol/g diet, aluminum concentrations in bone were reduced without a change in growth of rats. A reduction (approximately 30%) in kidney function, which was insufficient to alter growth, increased aluminum retention in bone by 34% in rats injected with aluminum and by 13% in rats fed aluminum. Rats fed aluminum seemed to retain in tissues only 0.01 to 0.05% as much aluminum as those injected with aluminum. Thus, tissue concentrations of aluminum, and presumably toxicity, can be altered by moderate changes in diet and kidney function even though overall retention of orally administered aluminum is extremely low.

Aluminum↗

Effects of prenatally administered thyroid hormones or glucocorticoids on maturation of kidney function in newborn rats.

Influences of treatment with thyroid hormones or dexamethasone during pregnancy on development of kidney function were studied in newborn rats. Treatment of dams for 3 days is followed by a higher rate of urine production in newborn rats. A statistically significant raise of sodium/potassium ratio in tetraiodothyronine- or dexamethasone-treated rats indicates a higher degree of maturation of kidney function. Treatment of dams with dexamethasone is followed by an increase of absolute excreted quantities of sodium and potassium in newborn rats. Treatment of dams with triiodothyronine can increase renal excretion of p-aminohippurate in newborn rats.

Animals↗

[Effect of a blockade of the upper complex of the cervical neural structures on kidney function in patients after operations on the abdominal cavity organs].

The authors have included blockade of the upper complex of nervous structures of the neck in the program of treatment of patients after operations on the organs of the abdominal cavity. Studies on the urine-eliminating function of the kidneys and radioisotopic rhenography were performed in 105 patients before and after operation. The results show that the blockade contributes to prevention of functional disorders in the cells of renal tubules and to the improvement of the urine-eliminating and general hemocatharsic function of the kidneys.

Abdomen↗