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Kidney function and size in diabetics before and during initial insulin treatment.

GFR, RPF, and kidney size were measured in nine young recently diagnosed insulin-dependent diabetics before (days 0) and 3 and 8 days after the beginning of the initial insulin treatment and in comparable control subjects. Kidney function was measured by a constant infusion technique using I-125-iothalamate and 131-I-hippuran. Kidney size was determined by means of ultrasound. Before insulin treatment elevated values for GFR (+44%, P less than 0.01), RPF (+18%, P less than 0.05), and kidney size (+29%, P less than 0.01) were found. Near-normal metabolic control was achieved in all patients using either multiple subcutaneous injections of insulin or an artificial betacell. GFR decreased from 160 +/- 9 SEM to 141 +/- 6 ml/min X 1.73 m2 (P less than 0.01) and further to 133 +/- 5 ml/min X 1.73 m2 (P less than 0.01, compared to day 0). Renal plasma flow was 601 +/- 33 and 588 +/- 44 ml x 1.73 m2 at days 0 and 3, respectively (NS) and decreased to 558 +/- 35 ml/min x 1.73 m2 at day 0 (P less than 0.01). By contrast no statistically significant changes in kidney volume were observed; the results on day 0, 3 and 8 were 145 +/- 7, 162 +/- 11 and 143 +/- 9 ml/1.73 m2, respectively. The present study demonstrates that kidney size and function are elevated at the onset of insulin-dependent diabetes. Near-normal metabolic control; for 8 days induces a reduction but not a complete normalization in kidney function. From the present observations it is suggested that the rapidly reversible part of the elevation in GFR cannot be explained by concomitant changes in kidney and glomerular size (morphological origin) but is probably due to a reduction in renal plasma flow and to a decreased transglomerular pressure (functional origin).

Adult

[NAG (N-acetyl-beta-D-glucosaminidase)--a sensitive marker for disorders of kidney function].

In a clinical study we tested the use of the lysosomal enzyme NAG as a parameter of kidney function. Following prospective randomization, we examined NAG excretion during cisplatin treatment with/without nephroprotection, after intravenous urography with ionic/non-ionic contrast media, during lower/upper urinary tract infections and before/after extracorporeal shockwave lithotripsy for intrarenal calculi (first-generation equipment used). Measurements were performed in 3-h urine specimens and in urine collected over 24 h, using a simple method of analysis. A correlation between NAG leakage and functional disorder of the renal tubular cells seemed likely on the basis of additional clinical and experimental data. Increases, in some cases dramatic, in NAG excretion were observed after the administration of cisplatin and ionic contrast media, in acute pyelonephritis, and after extracorporeal shockwave lithotripsy. However, the increase in NAG excretion was less impressive during cisplatin therapy when nephroprotective amino acids were infused, and in the urography group when non-ionic contrast media were used. Infections of the lower urinary tract did not increase NAG excretion. The results indicate that NAG is a sensitive marker of occult renal dysfunction, which can be checked by non-invasive techniques and can be used in a clinic setting to detect functional disorders of the kidney.

Acetylglucosaminidase

Effects of nitrendipine on blood pressure, renin-angiotensin system, and kidney function in essential hypertension.

The effects of nitrendipine (10 mg b.i.d.) on blood pressure, renin-angiotensin-aldosterone system, and kidney function (by means of glomerular and tubular function) were studied in comparison to captopril (50 mg b.i.d.) and to nitrendipine (10 mg q.d.) + captopril (25 mg b.i.d.) in 30 untreated essential mild-to-moderate hypertensives. The blood pressure lowering effect was similar with either regimen. Nitrendipine showed an acute and chronic natriuretic effect not accompanied by modifications of kidney function. All regimens were well tolerated by the patients without any appreciable side effects over the 4-week study period.

Adult

99mTc-DTPA scintillation-camera renography: a new method for estimation of single-kidney function.

A new method of combined serial scintigraphy and renography, using a scintillation camera and 99mTc-DTPA is evaluated. Renographic curves, corresponding to light-pen "areas of interest" over the renal parenchyma, were processed. "Blood-background" curves were recorded from an external detector over the temporal region of the head and also from an "area of interest" corresponding to the aorta and inferior vena cava. The uptake phase of the renogram was always linear. The sum of the slopes of the uptake phase of both kidneys correlated well with the measured glomerular filtration rate in 25 patients with renal insufficiency of various degrees. Single-kidney function estimated from the slopes correlated reasonably well with single-kidney function estimated from 131I-Hippuran renography with external detectors. The method described minimizes errors in the estimation of single-kidney function, and both anatomic and functional information is obtained.

Humans

On the natural tendency to progressive loss of remaining kidney function in patients with impaired renal function.

Patients who lose more than 50% of their functioning renal mass are at risk to develop progressive deterioration of their remaining kidney function, even though the process that caused the original loss of kidney function may no longer be present. The glomerular capillary hyperperfusion, hypertension, and hyperfiltration that occur in the surviving nephrons may play an important role in the natural tendency for renal function to deteriorate. Nevertheless, recent studies suggest that these glomerular hemodynamic events may not be the final common pathway for the natural deterioration of renal function, as was once thought. With regard to the general management of patients with impaired renal function, recent evidence suggests that controlling systemic blood pressure, reducing dietary protein and phosphorus intake, and controlling hyperlipidemia may be effective in slowing the loss of renal function.

Hormones

Effect of blood purification on the kidney function of the jaundiced rat.

This paper is aimed at evaluating the effect of blood purification on the mitochondrial functions of the kidney in jaundiced rats. At 1, 2, or 3 weeks after bile duct ligation and dissection, obstructive jaundiced rats were utilized for experiment. Cross circulation in 1 ml/min between jaundiced rats and normal rats was performed for 1 or 3 h. Immediately and 24 h after cross circulation, the rats were killed and mitochondrial respiratory functions of the kidney were assessed by measuring oxygen consumption. Mitochondrial function, especially ATP synthesis, showed significant improvement in jaundiced rat with 2 or 3 weeks of biliary obstruction. Cross circulation for 3 h was more effective than that for 1 h. These data suggest that the renal energy production can be increased significantly in obstructive jaundice by blood purification treatment.

Animals

[Artificial respiration and kidney function disorder--a vicious circle?].

Acute lung disease is commonly associated with interstitial pulmonary edema and a tendency towards partial or total alveolar collapse. To counteract this tendency mechanical ventilation is successfully used in most cases. Mechanical ventilation, however, leads to a harmful retention of water and salt, which may worsen interstitial pulmonary edema and further impair gas exchange. This problem seems to be less known. A survey of the effects of currently used modes of mechanical ventilation on excretory function and hemodynamics of the kidneys is given together with a short review of the possible afferent and efferent mechanisms which mediate the renal response to mechanical ventilation. Some clinical suggestions are made to break through the vicious cycle between mechanical ventilation and kidney function.

Animals

Early detection of changes in kidney function in workers exposed to solvents and heavy metals.

Increases in urine concentration of specific proteins have been proposed as early indicators of deleterious changes in kidney function. Four urinary proteins (albumin, superoxide dismutase, transferrin and N-acetyl-beta-D-glucosaminidase) were measured in workers exposed to heavy metals and solvents. None of the workers had clinical evidence of renal disease or hypertension. Workers exposed to mercury had a significant increase in urinary transferring, superoxide dismutase levels were slightly increased in workers exposed to solvents and lead, follow-up of these workers is needed to confirm that these changes predict late clinical deterioration of kidney functions.

Chemical Industry

Comparison of effective renal plasma flow (ERPF) and endogenous creatinine clearance (Ccr) in evaluation of the differential kidney function: an in vivo study.

Eleven patients with obstructive uropathy were inserted with a pigtail catheter either for urinary diversion, endopyelotomy or percutaneous nephrolithotomy. Differential kidney functions were obtained by single-sample technique with I-131 orthoiodohippurate (OIH) and separate endogenous creatinine clearance (Ccr). Good linear correlation was noted between effective renal plasma flow (ERPF) and Ccr (r = 0.84, p less than 0.005), but there was still some discrepancy between these two examinations, chiefly found in two severely obstructed kidneys. Determination of ERPF by I-131-OIH single-sample technique is a simple, rapid, inexpensive and relative accurate test to measure the differential kidney function. But if the ERPF is at extremely low level, further investigations such as sonography of kidney and separate endogenous creatinine clearance should be done to avoid unnecessary nephrectomy.

Adolescent

Effect of different linoleic acid intakes on prostaglandin biosynthesis and kidney function in man.

Prostaglandin (PG) biosynthesis and kidney function was investigated in 24 adults (23 to 32 yr) during isocaloric formula diet periods, for 2 wk each, providing a linoleic acid supply of 0, 3, 3.5, 4, 6, 8, 13, 17, 18, or 20% of total energy intake. Total protein intake (15 energy %) was constant, as well as 5 g NaCl, 3 g KCl, and 0.6 g cholesterol per 2200 kcal formula diet. The amount of PG metabolites, PG-E, sodium, and creatinine in 24-h urine increased with augmented linoleic acid intake. Comparing a linoleic acid intake of 0 and 20 energy %, an increase of sodium (8%) and creatinine (16%) in 24-h urine was found on the 5th day of high linoleic acid supply. Coincidently a stimulated PG biosynthesis could be measured. Potassium, water, and PG-F excretion showed no relation to linoleic acid intake. It is concluded that linoleic acid in the diet stimulates PG-E biosynthesis in man, leading to effects in systems which control renal function, and may have clinical relevance for the sodium and potassium balance in man.

Adult

[Changes of kidney function in obese subjects during absolute fasting (author's transl)].

In 28 obese subjects the influence of a 15-days fasting period on the kidney function was investigated by continuous measurement of the clearances for creatinine, urea and uric acid. In the course of fasting time the serum concentrations of creatinine in comparison to the initial value significantly increased, the creatinine clearance maximally decreased about 40%. The serum concentrations of urea were found lower, whilst the clearance of urea increased. Moreover a distinct increase of the serum levels in connection with a significant decrease of the uric acid clearance was to be observed. Under conditions of strict fasting changes of the kidney function are evident, whose intra- and extrarenal reasons are discussed.

Adult

[Specific features of postoperative infusion therapy depending on kidney function in newborn infants with developmental defects].

Results of examination of partial functions of the kidneys in 113 newborns have shown the reaction of the kidneys on a surgical aggression to be dependent on the age and stage of the postoperative period. The reaction manifests itself by renal economy of water and electrolytes on the 1-3 days after operation followed later by the osmotic dilution of urine and lower reabsorption of sodium and potassium. The maximum amount of sodium admissible for administration in the postoperative period has been established with special reference to age.

Age Factors

Comparative effects of enalapril, atenolol and chlorthalidone on blood pressure and kidney function of diabetic patients affected by arterial hypertension and persistent proteinuria.

Arterial hypertension and proteinuric nephropathy are common features in diabetic patients. In streptozotocin-diabetic rats, it has been possible to reduce the blood pressure and proteinuria by converting enzyme inhibitors, and so slowing the decline of kidney function. These results have been confirmed in diabetic patients affected by arterial hypertension and persistent proteinuria. However, up to now it has not been clear if these favorable renal effects are related specifically to converting enzyme inhibition. In the attempt to clarify this last point, from a practical as well as from a speculative point of view, 12 type 2 diabetic outpatients affected by mild to moderate arterial hypertension and persistent macroalbuminuria (greater than 250 mg/daily, at least on three consecutive occasions) without any other signs of renal diseases were studied. In a randomized sequence and in a double blind fashion, after a washout period of 3 weeks, the patients underwent pharmacological treatment which consisted of enalapril 20 mg o.d., chlorthalidone 12.5 mg o.d., atenolol 50 mg o.d. and placebo o.d. Each treatment lasted 45 days. Kidney function, blood pressure and heart rate were checked at the beginning and at the end of each treatment, while urinary albumin excretion was measured at the end of the 4th, 5th, and 6th week of each treatment. Blood pressure significantly decreased in a similar fashion after each active treatment, while kidney function did not change significantly. Urinary albumin excretion rate significantly decreased after enalapril and atenolol, but did not change after chlorthalidone. According to these results we can hypothesize that the inhibition of tissue angiotensin formation and its related change on the glomerular permeability, rather than renal and systemic hemodynamic features, seem to be the common mechanisms by which both enalapril as well as atenolol decrease the albuminuria in our patients.

Atenolol

The relationship between the renal clearance of creatinine and the apparent renal clearance of beta-2-microglobulin in patients with normal and impaired kidney function.

The renal clearances of creatinine and beta 2-microglobulin of patients with either normal or impaired kidney function were measured. The renal clearance of beta 2-microglobulin depends on the urinary pH and must be considered as an apparent renal clearance because after tubular reabsorption the compound is metabolized in the kidney. Impaired kidney function reduces the percentage of tubular reabsorption of beta 2-microglobulin.

Absorption

Kidney function during hydropenia nad water diuresis in patients with idiopathic recurring nephrolithiasis.

The kidney function of 41 patients with idiopathic recurring kidney stones was investigated by inulin- and PAH-clearances and by measuring the excretion of electrolytes during hydropenia and water diuresis. All patients had normal inulin- and PAH-clearances and normal concentrating capacity as indicated by free water reabsorption (Tc H2O). Seven patients, all of whom had previously been found to have low excretion of magnesium in urine, were unable to dilute their urine. During water diuresis these patients also had lower osmolar clearance and lower excretion of sodium than the other patients. A defective dilution capacity may be of pathogenetic significance for stone formation; the causes of the defect, however, are not clear.

Adult

Kidney function in rats with corticomedullary nephrocalcinosis: effects of alterations in dietary calcium and magnesium.

Single-nephron and whole-kidney function were studied in female rats with corticomedullary nephrocalcinosis, and in animals where the lesion had been prevented either by a dietary magnesium supplement or by using a diet with a calcium:phosphorus ratio in excess of 1. At the single-nephron level, rats with nephrocalcinosis had prolonged tubular fluid transit times. Proximal transit time was 19.42 +/- 1.98 (mean +/- S.E. of mean) vs. 11.58 +/- 0.19 s for controls; distal transit time was 62.64 +/- 9.16 vs. 31.50 +/- 1.03 s for controls. Although single-nephron function is altered in nephrocalcinosis, data obtained from rats in metabolism cages indicate that whole-kidney function is largely unaffected by the lesion.

Animals

Creatinine excretion rates for evaluation of kidney function in children.

A protein load protocol for evaluation of kidney function was tested in normal children and pediatric renal patients. An overnight, timed urine collection was used for calculation of the baseline creatinine clearance and creatinine excretion rate. One hour following ingestion of a standardized protein meal (baked chicken), a 2-3 h urine collection was begun. The post-protein meal changes in creatinine clearance showed considerable variation in both the normal children and those with renal disorders. In contrast, the rate of excretion of creatinine was consistently increased in the normal children following the protein meal (73.4 +/- 18%; range 48.2%-122.4%). Of 33 renal patients, 14 showed less than a 48% increase in creatinine excretion rate, even though 9 of these children had baseline creatinine clearances within the normal range. These 9 patients have evidence of less than normal quantities of functioning renal tissue. Serial studies over a year on 2 children who presented with acute renal failure showed a progressive increase in creatinine clearance with scant increases in creatinine excretion rate. These studies provide indirect evidence that a less than normal enhancement of the rate of creatinine excretion following a protein load reflects the presence of adaptive glomerular hyperfiltration and hyperperfusion.

Adolescent