Renal and cardiovascular effects of renal medullary damage with bromoethylamine in dogs

Bromoethylamine (BEA, 30-40 mg/kg) was administered to dogs to determine whether damage to the inner medulla of the kidney, the putative source of a depressor hormone, causes hypertension in this species. Bromoethylamine produces hypertension in rats but this has not been confirmed in other species, although we have shown that this dose of BEA in dogs abolishes the release of a reno-medullary vasodepressor hormone in response to marked increases in renal perfusion pressure. During acute BEA administration over 1 h to conscious dogs, there were no significant effects on renal blood flow, arterial pressure or total peripheral resistance, but there was a significantly greater diuresis compared to vehicle administration. Over the first 10-14 days after BEA, daily urine output rose 5-10 fold initially and plasma creatinine concentration rose markedly. There was no significant effect on arterial pressure, cardiac output, total peripheral resistance, or renal blood flow over this period. BEA administration caused extensive damage to the thin limbs of the loops of Henle, widespread thrombosis of blood vessels and haemorrhage into the interstitium of the dog renal medulla. Reno-medullary interstitial cells were devoid of lipid droplets, were synthetic, and were associated with increased amounts of extracellular matrix. Thus extensive renal medullary damage by BEA administration to conscious dogs did not alter resting systemic haemodynamics, and these results therefore provide no evidence for a role for the medulla in the maintenance of resting arterial pressure in the dog.

Unilateral renal papillectomy via laser or incisional techniques: chronic functional effects in the dog

OBJECTIVE

To determine if selective renal papillectomy would impair urinary concentrating ability, thereby decreasing urinary calcium concentration.

METHODS

Left papillectomy was performed in dogs using either incisional (n = 6) or Neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (n = 5) techniques. Split renal function studies were then performed four months postoperatively to determine the effect on multiple parameters including inulin and para-aminohippurate (PAH) clearance, free water reabsorption, and calcium concentrations. Partially infarcted kidneys (n = 6) were evaluated in a similar fashion to determine the role of impaired glomerular filtration rate (GFR) in the observed concentrating defect occurring after papillectomy.

RESULTS

Papillectomized kidneys demonstrated impaired free water reabsorption, resulting in a decreased urinary osmolality and an increased fractional excretion of water. Osmolar clearance [Na+] and Na+ excretion were unaffected by papillectomy, whereas [Ca++] was significantly reduced. While a slight defect in free water reabsorption existed following partial infarction, urinary osmolality was only minimally decreased, fractional excretion of water was unchanged, and Na+ excretion was decreased.

CONCLUSIONS

The concentrating defect induced by papillectomy via either sharp excision or laser ablation is due to loss of medullary tissue and is greater than the defect resulting from impaired GFR, which is presumably due to decreased medullary solute delivery and increased flow of water in remaining nephrons. Since the physiologic consequences of papillectomy (formation of less concentrated urine with decreased [Ca++]) have potential clinical applicability, further study of this concept is warranted.

DNA damage in the kidneys of diabetic rats exhibiting microalbuminuria

8-Hydroxydeoxyguanosine (8-OHdG), an oxygen radical induced modification of purine residue in DNA, was measured in the liver, pancreas, and kidney of streptozotocin-induced diabetic rats (STZR) exhibiting microalbuminuria. At 4 weeks after the injection of streptozotocin (50 mg/kg, i.v.), the rate of urinary albumin excretion was 0.5 +/- 0.1 and 2.0 +/- 0.2 mg/24 h in age-matched control rats (CR) and STZR, respectively. Compared to CR, STZR also showed a significantly increased level of 8-OHdG in the kidney but not the liver and pancreas. Amounts of 8-OHdG/10(5) dG for CR and STZR were 3.4 +/- 0.3 and 5.1 +/- 0.2 for renal cortices, and 4.1 +/- 0.2 and 20.0 +/- 3.7 for renal papillae. Daily injection of insulin (2 U, SC) starting on the third day after streptozotocin treatment significantly reduced both urinary albumin excretion and papillary 8-OHdG formation, which suggests that these are associated with the diabetic state induced by streptozotocin rather than a direct nephrotoxic effect of the drug. This study suggests that formation of 8-OHdG and, therefore, oxidative damage are closely related in the process of diabetic nephropathy.

Influence of nifedipine on stone formation and renal function in cholesterol-induced nephrolithiasis in rats

Previous investigations showed that nifedipine limited calcium phosphate stone formation induced by a high-cholesterol diet in rats. This study was performed to obtain further insights into the effects of nifedipine on stone prevention, renal function and urine composition. Male Wistar rats were assigned to one of the following groups: (1) cholesterol diet (n = 22), (2) cholesterol diet plus nifedipine (n = 22) and (3) control (n = 6). A high-cholesterol diet was given for 4 weeks, nifedipine was administered by gavage to group 2 for 4 weeks (50 mg/kg/24 h). During weeks 1 and 4, 5 rats of each group were housed in metabolic cages for urine collection. Sodium (Na), calcium (Ca), magnesium (Mg), phosphate (P(i)), citrate and creatinine were determined in the urine. The kidneys of 4 animals of group 1 and 2 were perfused and removed for histology after 1, 2, 3 and 4 weeks, respectively. Clearance studies (inulin, Na, Ca, Mg, P(i)) were performed (n = 6/group) after 4 weeks. The cholesterol diet induced a marked renal stone formation which was significantly limited by nifedipine [calcification index (week 4) 1.75 +/- 0.5 vs. 0.75 +/- 0.5]. The sequential histological examinations showed that concrement formation started intracellularly after only 1 week in group 1, whereas in group 2 the first concretions were observed only after 3 weeks. The cholesterol diet induced an increased excretion of Ca and P(i) citrate and Mg were reduced. The concomitant application of nifedipine resulted in a higher excretion of Ca, Mg and citrate when compared to the cholesterol group. The inulin clearance was decreased in the latter group.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal corticomedullary differentiation: observation in patients with differing serum creatinine levels

PURPOSE

To evaluate renal corticomedullary differentiation (CMD) in patients with differing serum creatinine (sCr) levels.

MATERIALS AND METHODS

Ten patients with normal sCr levels (0.9-1.3 mg/dL [80-115 mumol/L]), 14 with mildly elevated levels (1.5-2.9 mg/dL [133-256 mumol/L]), and 15 with elevated levels (> 3.0 mg/dL [265 mumol/L]) were examined with unenhanced T1-weighted fat-suppressed spin-echo (T1FS) and immediate gadolinium-enhanced gradient-echo (Gd-GRE) imaging.

RESULTS

Patients with normal sCr levels had CMD on T1FS and Gd-GRE images. Among patients with mildly elevated levels, seven did and seven did not have CMD on T1FS images; all had CMD on Gd-GRE images. Patients with elevated levels had no CMD on T1FS images; 13 had CMD on Gd-GRE images. Two patients with levels above 10.0 mg/dL (884 mumol/L) had no CMD on Gd-GRE images.

CONCLUSION

Independent of the cause of elevated sCr level, levels above 3.0 mg/dL result in loss of CMD on T1FS images, while levels above 10.0 mg/dL result in loss of CMD on Gd-GRE images.

Urinary acidification and urinary excretion of calcium and citrate in women with bilateral medullary sponge kidney

Urinary acidification ability, acid-base status and urinary excretion of calcium and citrate were evaluated in 10 women with bilateral medullary sponge kidney (MSK) and in 10 healthy women. Patients with MSK had higher fasting urine pH compared to normal controls (p < 0.01). Four patients had incomplete renal tubular acidiosis (iRTA), 3 had hypercalciuria, and 5 patients had hypocitraturia. The 24-hour urinary excretion of calcium was increased in the females with MSK (5.23 +/- 0.78 mmol) compared to the healthy females (3.49 +/- 0.29 mmol) (p < 0.02), and increased in MSK patients with iRTA (7.32 +/- 1.45 mmol) compared to patients with normal urinary acidification (3.83 +/- 0.12 mmol) (p < 0.01). The patients with iRTA had reduced levels of plasma standard bicarbonate (20.5 +/- 1.0) after fasting compared to patients with normal urinary acidification (23.8 +/- 0.8) and healthy women (22.7 +/- 0.6) (p < 0.01), and reduced levels of 24-hour urinary excretion of citrate (0.93 +/- 0.25 mmol) compared to patients with normal urinary acidification (3.58 +/- 0.51) and healthy women (2.78 +/- 0.49) (p < 0.005). A positive correlation was found between the degree of acidosis during ammonium chloride loading and urinary excretion of calcium (r = 0.71, p = 0.02), and a negative correlation between the degree of acidosis during ammonium chloride loading and urinary citrate excretion (r = 0.87, p = 0.001). The results suggest that defective urinary acidification might play an important role in the mechanism of hypercalciuria and hypocitraturia in patients with medullary sponge kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors affecting human autopsy kidney-cortex and kidney-medulla platinum concentrations after cisplatin administration

The objective of this study was to determine factors that affect cisplatin concentrations in human kidney cortex. We used flameless atomic absorption spectrophotometry to assay platinum in autopsy specimens of kidney cortex obtained from 83 cisplatin-treated patients. Concentrations were correlated with pretreatment factors and treatment conditions using univariate nonparametric statistics. Hierarchical stepwise multiple regression analyses of transformed (to normalize) data were then used to assess which factors were most important, controlling for other factors. Kidney-cortex platinum concentrations varied from 0 to 14.8 micrograms/g (median, 2.04 micrograms/g). The cumulative lifetime dose of cisplatin ranged from 10 to 1120 mg/m2 (median, 112 mg/m2). The time from the last cisplatin dose to death was < 1-609 days (median, 38 days). According to univariate statistics, factors that correlated (P < 0.05) with kidney-cortex platinum concentrations were the cisplatin dose per course, the pretreatment serum urea level, metoclopramide use (positive correlations), the time from the last cisplatin treatment to death, and the pretreatment serum albumin value (negative correlations). Factors that approached significance (0.05 < or = P < or = 0.10) were a history of hypertension, hyperbilirubinemia (positive), the serum calcium level, and phenytoin use (negative). In the multiple regression analysis, after controlling for the cisplatin dose per course and the time from the last treatment to death, only concurrent metoclopramide and phenytoin use entered the model. The hydration volume did not affect corrected kidney-cortex or kidney-medulla platinum concentrations. The following conclusions were reached: (1) it may be feasible to use lower hydration volumes than those used routinely, (2) any effect of hydration volume on cisplatin nephrotoxicity may not be mediated via a reduction in kidney-cortex platinum concentrations, (3) higher cisplatin doses might be tolerated with new 5-hydroxytryptamine-3 (5HT-3) antiemetics than were tolerated with metoclopramide, and (4) phenytoin should be tested for its ability to reduce cisplatin nephrotoxicity.

The effect of hydroxyl-containing dithiocarbamates on cisplatin-induced long-term renal dysfunction in Wistar rats

The possibility of a slow, longer term deterioration in renal function following the administration of cisplatin has been little studied in animal models. To obtain data on this we have examined renal function and histopathology at 30 days post i.p. cisplatin (5 mg/kg) treatment in female Wistar rats with and without the administration of hydroxyl-containing dithiocarbamates as a protective measure. In contrast to the studies terminated at shorter times, the degree of protection furnished by the use of dithiocarbamates at longer times post-treatment is less impressive. Results suggest that a continuing deterioration in renal function occurs at times greater than 1 week post-treatment when such dithiocarbamates are administered at 1 and 3 h post cisplatin. This was evidenced in both several measures of renal function and in the histopathology of the S3 segment of the proximal tubule.

[Morphometric studies on the cortex and medulla of frontally sectioned kidneys in the Japanese adult]

The cortex and medulla areas, sectioned frontally, of 50 kidneys from 25 dissecting cadavers were measured to determine the correlation between differences in sex, laterality, and age. The average parenchyma (cortex + medulla) area was 33.45 +/- 9.16 cm2 and was larger in men than women; there was no significant laterality, but the parenchyma area was negatively correlated with age. The average cortex area was 20.39 +/- 5.80 cm2 and was also larger in men than women; laterality was not significant, and the cortex area was negatively correlated with age. The average medulla area was 13.05 +/- 4.40 cm2, and no significant difference in sex or laterality was found. The medulla area was negatively correlated with age. Additionally, the average number of renal pyramids (medulla) was 6.24 +/- 1.45 on these sections. Difference in the average areas of cortex and medulla was significant. The medulla was exceptionally larger in two cases (4%). The ratio between the average area of the cortex and medulla (C/M ratio) was 1.67 +/- 0.56. No sex difference or laterality was found, nor was there a correlation between the C/M ratio and age or kidney size. The sectioned area of cortex was approximately 1.5 to 2 times larger than medulla. These results suggest that senile atrophy may occur at the same rate in the renal cortex as in the medulla.

Pathology of renal dysplasia and bladder aplasia-hypoplasia in a flock of sheep

Congenital renal disease was detected in a flock of sheep in the English Midlands over 2 successive years (1982 and 1983). A Suffolk ram was removed from the flock and test mated to unrelated Suffolk ewes in another flock; 14 of the resulting 43 lambs born in 1984 had an identical congenital renal disease. Kidneys were examined microscopically from 60 clinically affected neonatal lambs. Kidneys from 7 of the 60 clinically affected neonatal lambs (1, 1983; 6, 1984) were examined ultrastructurally and compared with kidneys from 3 healthy unrelated neonatal lambs. Most affected lambs examined (52/60) had bilaterally small kidneys (< or = 2 g) with fine intracortical cysts and distinct cortical and medullary zones. Kidneys were either grossly normal (3/60 lambs) or multicystic and of normal size to markedly enlarged (5/60 lambs). The bladder was absent or vestigial in most lambs. Microscopically, poorly differentiated ("primitive") tubules were present in renal cortex and medulla. Proximal convoluted tubules, where present, were formed by epithelial cells with distinctive round weakly autofluorescent intracytoplasmic inclusions with the ultrastructural appearance of atypical lysosomes. Loops of Henle, distal convoluted tubules, and juxtaglomerular-peripolar cell complexes were largely absent. Glomerular changes were minimal. Cystic dilatation of nephrons was restricted to proximal convoluted tubules lined by vacuolated epithelium. This distinctive congenital renal dysplasia of sheep was most likely inherited as a dominant trait with complete penetrance.

Differential diagnosis of solid renal tumors by MRI. Comparison of in situ relaxation times measured with a 0.1 T imager and histological findings

The T1 and T2 of kidneys in 5 normal volunteers and 27 patients with renal tumors were evaluated preoperatively using a magnetic resonance imager with a 0.1 T resistive electromagnet, and the T1 and T2 of the renal tumors were compared with the pathological findings: (i) the T1 and T2 of the normal renal medulla were longer than those of the normal renal cortex and psoas muscle; (ii) both T1 and T2 of renal pelvic cancer (RPC) were shorter than those of renal cell cancer (RCC, p < 0.05); (iii) the T2 values of RPC were significantly shorter than those of renal medulla (p < 0.01); (iv) the T1 and T2 of the normal renal cortex of subjects < 50 years old were shorter than those of subjects > or = 50 years old (p < 0.05 and p < 0.01, respectively). These findings suggest that preoperative evaluation of the pathological findings of renal tumors may be possible by calculating the relaxation time using MRI under low magnetic field.

Renal papillary cytoplasmic granularity and potassium depletion induced by carbonic anhydrase inhibitors in rats

Renal papillary cytoplasmic granularity (RPCG) induced by carbonic anhydrase inhibitors (CAIs) in rats is characterized by the accumulation of dense secondary lysosomes in epithelial, endothelial, and interstitial cells and may be related to drug-induced potassium depletion. Female Sprague-Dawley rats were given the CAI, acetazolamide, by gavage. Half were supplemented with 1% potassium chloride in the drinking water. Two treated groups were allowed to recover for 1 or 2 mo. Potassium supplementation inhibited RPCG by 80% but produced little amelioration of the mild 13% decrease in serum potassium induced by 200 mg/kg/day acetazolamide for 28 days. Acetazolamide-induced RPCG is reversible because 1- and 2-mo recovery periods decreased the incidence by 75% and 80%, respectively. The results support the hypothesis that RPCG is related to potassium depletion secondary to carbonic anhydrase inhibition. Because supplementation of potassium chloride had little effect on serum potassium, these data suggest that depletion of renal medullary potassium content is important in the pathogenesis of RPCG as previously suggested by others. Other types of diuretics that produce hypokalemia as a side effect may not deplete medullary potassium since RPCG has not been reported in humans or animals given these drugs.

Epithelia hyperplasia in the renal papilla and pelvis but not the urinary bladder of male F344 rats associated with dietary sodium phosphates after uracil exposure

Effects of the bladder tumor promoter Na3PO4 and the non-bladder-tumor promoter NaH2PO4 on development of hyperplastic lesions of urinary bladder and renal papilla/pelvis were investigated after exposure of male F344 rats to the nongenotoxic carcinogen uracil. Animals were administered with 3.0% uracil in the diet for 4 weeks and thereafter fed 3.0% Na3PO4 or 3.0% NaH2PO4 for 32 weeks. No enhancing effect of either phosphate salt on uracil-induced proliferative lesions of urinary bladder was observed. However, the sequential treatments gave rise to enhanced development of hyperplastic lesions in the renal papilla/pelvis compared to the case with uracil alone. In addition, a small number of renal pelvic papillomas were observed in the group given Na3PO4 after uracil. These phosphate salts also induced nephrocalcinosis in the papilla/pelvis concomitant with development of renal hyperplastic lesions in this location. A sequential study revealed calculus formation and proliferative lesions in both the urinary bladder and renal papilla/pelvis after 4 weeks dietary application of uracil. After cessation, calculi disappeared and the majority of hyperplastic lesions regressed, consistent with a decrease in DNA synthesis levels. Persistence of uracil-induced epithelial hyperplasia in renal papilla/pelvis under the influence of phosphate salts might have been directly due to chronic stimulation by nephrocalcinosis in these sites.

Renal cysts in the carbohydrate-deficient glycoprotein syndrome

The carbohydrate-deficient glycoprotein (CDG) syndrome is a newly described genetic disorder with autosomal recessive inheritance and multiple organ involvement. We describe five patients with the CDG syndrome who all had abnormal renal structure. In two patients autopsy disclosed multiple microcysts. A hyperechogenic pattern strongly suggesting microcysts was demonstrated in all patients that were available for ultrasound examination, while a large single cyst was also seen in one patient. Based on these findings and the reports of others, renal cysts appear to be common in the CDG syndrome.

Adaptation of the medullary thick ascending limb to dietary protein intake

Since the renal growth response to a high-protein diet is characterized by prominent hypertrophy of the medullary thick ascending limb of Henle's loop (MTAL), the functional and metabolic adaptations of this nephron segment to dietary protein were investigated. MTAL suspensions were obtained from rats fed equal amounts of isocaloric food containing either 10% (LP) or 32% (HP) casein for 4-6 weeks. The results show that intact MTAL of HP rats exhibit a blunted respiration rate, sodium pump activity, hormone-sensitive cAMP production and leucine oxidation rate in comparison with those of LP rats. On the other hand, adenylate cyclase and leucine transaminase activities, measured on permeabilized or homogenized MTAL, are enhanced by a HP diet. We conclude that the MTAL adapts to high dietary protein by increasing its maximal enzyme activities, but certain factors, present in intact cells, limit transport and metabolism in HP- more than in LP-fed rats. This reduced function per unit MTAL protein in HP rats is more than compensated for by hypertrophy of the MTAL tissue mass.

Classification of tubulo-papillary renal cortical tumours using estimates of nuclear volume

The classification of renal cortical tumours is problematic, with no clear division of benign from malignant tumours. Unbiased stereological estimates of volume-weighted nuclear volume (nuclear vv) were obtained by point sampling of nuclear intercepts in a retrospective study of 36 variably sized tubulo-papillary basophilic cell renal cortical tumours. There was no clear pattern of evolution of nuclear vv with increasing macroscopic tumour diameter. Estimates of nuclear vv could not distinguish between 21 tumours classified as renal adenomas with macroscopic diameters < 3 cm (average nuclear vv = 241 microns 3) and 15 tumours classified as renal cell carcinomas with diameters > 3 cm, or aggressive histological pattern (average nuclear vv = 229 microns 3) (2p = 0.68). In this subtype of renal cortical tumours, estimates of nuclear vv do not support the historical convention of using a 3 cm tumour diameter as the dividing line between adenomas and carcinomas, but support the theory of a single group of tumours. As most of the truly incidental renal cortical tumours are less than 1 cm in diameter, this limit could be considered. Such small benign cortical nodules have never been reported to metastasize, and would thus be excluded from being diagnosed and registered as malignant. Although this dividing line is again arbitrary, and cannot be justified by the stereological measurements, it is a practical solution to a clinical problem. There were too few examples of disease progression to assess the prognostic significance of nuclear vv in these tumours.

Effects of anemia on morphology of rat renal cortex

Information on morphological and functional effects of anemia in kidney is scarce, although this organ plays a major role in erythropoietin production, which is strongly stimulated in anemia. We undertook a morphological study of kidneys of anemic rats. Anemia was induced by X-irradiation and subsequent injection of a hemolytic drug. The most striking effects of anemia on renal morphology were damages in the proximal tubule and a volume increase of the peritubular space. These effects were evident only in the cortical labyrinth. Morphometry showed that the enlargement of the peritubular space reflected an increase of the volumes of both capillaries and interstitium. The structural changes in the cortical interstitium were associated with increased activity of the ecto-5'-nucleotidase in the fibroblasts. We suggest that hypoxia accounts for most of the observed alterations. The hypoxic proximal tubule might release the nucleotide AMP, which would be hydrolyzed to adenosine by the ecto-5'-nucleotidase in the interstitium. Adenosine has been reported to trigger the synthesis of erythropoietin and the growth of blood capillaries.

Selective zonal change of the renomedullary interstitial cells in hypokalemic rats

Electron microscopic morphometry was undertaken to quantitate the morphological change of the renomedullary interstitial cells (RIC) of hypokalemic rats by using large montages. Two weeks of potassium depletion resulted in an increase of the RIC, which were restricted to the interbundle region of the inner stripe of the outer medulla. The increase of the RIC is characterized by a preferential increase in volume density (+340.0%; P < 0.01) and numerical density (+61.4%; P < 0.01) in the interbundle region but not in the vascular bundle of the inner stripe or in the inner medulla. The increased RIC in the interbundle region of the inner stripe demonstrated an increase of lipid droplets, which are known to contain prostaglandin precursors. The selective zonal change of RIC with increased lipid droplets is a characteristic lesion of hypokalemic rats and suggests an enhanced vasoactive function of RIC associated with hypokalemic nephropathy.

In vivo NMR imaging and spectroscopic investigation of renal pathology in lean and obese rat kidneys

Diabetic nephropathy is a major cause of end-stage renal failure. While our understanding of the pathogenesis of nephropathy is incomplete, progressive glomerular injury appears to play a significant role in the decline of renal function. Proton NMR spectroscopy and imaging techniques were used to address changes in renal pathology associated with glomerular mesangial expansion in vivo in kidneys from spontaneously obese and lean (control) littermate Zucker rats. Fully functioning rat kidneys were surgically exposed and externalized for direct NMR signal detection via a coil placed around the organ. High-resolution (78 microns in plane) proton images were obtained at 4.7 T magnetic field strength revealing fine structure within the well-defined cortical and medullary regions. The obese rat kidney images were distinct in appearance from the lean kidney images and exhibited marked cortical expansion as well as increased overall kidney size. Enlargement of mean glomerular diameter was verified histologically in the obese kidneys as compared with the lean kidneys. Proton T1 and T2 relaxation times were determined from the entire kidney using standard spectroscopic techniques, and from specific regions within the kidney from multiple T1- and T-2 weighted images. Additionally, image contrast enhancement resulting from saturation transfer between protons in restricted-mobility environments and mobile water protons within the kidney was investigated in the lean and obese rat kidneys using magnetization-transfer imaging techniques. At the early stage of renal injury examined in this study, diseased and healthy kidneys could not be differentiated on the basis of relaxation times alone. The magnitude of saturation transfer obtained in cortical tissue in the lean and obese kidneys was also not statistically significantly different. However, the magnitude of saturation transfer achieved in the medullary tissue of obese kidneys was statistically significantly less than that achieved in lean kidneys.

Effects of dietary protein on renal ischemia induced tubular necrosis

Previously we have shown that the amount of protein in a dietary regimen prior to the induction of renal ischemia will significantly affect the degree of postischemic acute renal failure (Andrews PM, Bates SB: Kidney Int 30:299-303, 1986). The present investigation was undertaken to determine what effect dietary protein regimen has on the histopathology of renal ischemia. Rats were pair-fed for 2 weeks on either 0% or 5% (restricted), 20% (normal), or 60% (high) purified protein isocaloric diets. Ischemia was induced by 45 min of renal pedicle clamping. Light and electron microscopic evaluation of kidney morphology immediately following renal ischemia (prior to blood reflow) revealed that the extent of morphological damage to cells lining proximal convoluted tubules and the thick ascending segments of Henle's loop increased with increasing concentration of dietary protein. However, all dietary protein groups also exhibited heterogeneity in the extent of damage to different nephrons within the same kidney.

Renal medullary fibroma: a case report and review

A case of renal medullary fibroma in a woman is presented. A CT scan, which was performed for examination of cholelithiasis, incidentally revealed a mass in the left renal pelvis, and retrograde pyelography showed a filling defect in the same site. Left nephrectomy was performed. Histological examination revealed a renal medullary fibroma. The diagnostic and therapeutic dilemmas associated with this condition are discussed.

Role of ultrasound in medical management of patients with renal stone disease

Eighty-three patients with radiographically opaque renal stones were evaluated prospectively with ultrasound and compared to KUB (kidneys, ureters, bladder) with tomograms (KUB/T) to further define the use of ultrasound in the evaluation of renal calculi. The presence or absence and the size, number, and location of stones were analyzed and correlated for each modality. Ultrasound detected the presence of renal stones in 77 of 83 (93%) patients. However, all of the stones were detected on ultrasound in only 60% of these patients. Thirty percent (80 of 269) of the papillary-calyceal stones seen on KUB/T were missed on US; 66% of the stones missed measured 2 mm or less. Although ultrasound can be used for detection of intrarenal stones, KUB/T is a more accurate imaging examination for determination of size and number of small stones.

Evidence for Randall's plaques to be the origin of primary renal stones

Lithofibrin, a non-protein organic component of renal calculi was found in renal papillas with the aid of stereo microscopy under UV illumination. Scanning electron microscopy revealed fibers of which one had a clump containing calcium on the top. The findings support the theory of Randall, that the origin of primary renal calculi is to be found in the kidney, not in the urine.

Tissue distribution of Neutrophils in postischemic acute renal failure

Polymorphonuclear neutrophil granulocytes (PMNs) seem to participate in the pathogenesis of renal ischemic reperfusion injury. The kidneys from male Sprague Dawley rats were immersion-fixed after 45 min of renal artery clamping followed by reperfusion for 0, 5, 20, and 120 min, respectively. The tissue distribution of PMNs in the kidneys was studied histochemically using naphthol AS-D chloroacetate esterase as a specific marker for these cells. Neutrophil counts per unit sectional area were obtained for renal cortex, outer and inner medulla. In the cortex separate intraglomerular and peritubular counts, and in the outer medulla separate outer and inner stripe counts were made. After 120 min of reperfusion the total renal PMN counts were 488 +/- 62 (n = 4) compared with 54 +/- 4 (n = 4) per cm2 in nonischemic controls. Within 120 min of reperfusion PMN counts increased by a factor of 8 in the cortex, of 12 in the outer medulla and of 14 in the inner medulla, compared with controls. The ratio of intraglomerular against peritubular PMN counts was approximately 2 in controls, but 0.5 after a 120-min reperfusion interval. The outer stripe of the outer medulla contained only a small number of PMNs whereas PMN counts of 923 +/- 197 (n = 4) per cm2 were found in the inner stripe after 120 min reperfusion. Interestingly, there was a marked increase in PMNs in the inner stripe during the first 5 min of reperfusion but no extravasation of PMNs was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Infarction of the kidney: role of contrast enhanced MRI

Magnetic resonance imaging was performed on nine kidneys in six patients with renal infarction caused by renal arterial embolism secondary to cardiac valvular disease. The time interval between the onset of the symptoms attributable to renal infarction and the date of MRI was 2-23 days. On both T1- and T2-weighted images the signal intensity of the infarcted area was lower than that of the noninfarcted area in six kidneys and higher in three kidneys. Postcontrast T1-weighted images demonstrated the extent of the infarction except in the kidney in which the infarcted areas had high signal intensity on precontrast T1-weighted images.