Immunohistochemical analysis of macrophages, myofibroblasts, and transforming growth factor-beta localization during rat renal interstitial fibrosis following long-term unilateral ureteral obstruction

Renal interstitial fibrosis was induced in rats by chronic unilateral ureteral obstruction (UUO). To identify the mechanisms behind the fibrosis, macrophage influx, myofibroblast involvement, and the localization of transforming growth factor-beta (TGF-beta, a fibrogenic cytokine) were investigated immunohistochemically in rats euthanatized at 0 (controls), 3, 6, 9, 12, and 15 days after UUO. The number of alpha-smooth muscle actin-positive myofibroblasts began to increase significantly in the medulla from day 3, and the development of medullary fibrosis was confirmed from day 6 by morphometric analysis. From day 9, papillary fibrosis also developed in association with an increased number of myofibroblasts. These myofibroblasts showed a parallel orientation to the mucosal surface of the pelvis. In the medulla and papilla, from day 6 the number of ED1 (primary antibody)-positive macrophages began to increase significantly. There appeared to be a relationship between macrophage influx and myofibroblast involvement. By contrast, in the cortex there was no marked increase in myofibroblasts nor development of fibrotic tissues, regardless of increased number of macrophages from day 6. Immunohistochemically, no staining for TGF-beta was found in infiltrating macrophages or myofibroblasts. However, TGF-beta was localized on some cortical proximal renal tubules both of normal control and obstructed kidneys in the early stages on days 3, 6, and 9, suggesting that the possible origin of TGF-beta may be renal epithelia. However, the staining intensity for TGF-beta on the renal epithelia tended to be weakened in advanced obstructed kidneys on days 12 and 15. The likely contribution of TGF-beta to the advanced stages of UUO-induced renal fibrosis remains to be determined.

Renal medullary cystic disease: assessment by MRI

Medullary cystic disease is an important cause of renal failure in adolescent patients. Imaging plays a primary role in the diagnosis of this entity as cysts are characteristically seen in the renal medulla and corticomedullary junction with normal to small sized kidneys. Imaging studies that do not use intravenous contrast or ionizing radiation are particularly useful given the young age of these patients and presence of renal failure. In this case, we demonstrate the imaging findings of medullary cystic disease by MRI.

Subchronic toxicity of benzothiophene on rats following dietary exposure

The systemic and neurobehavioral effects of benzo[b]thiophene (routinely referred to as benzothiophene) were studied in rats following 13-wk oral exposure. Male (170 +/- 16 g) and female (146 +/- 12 g) Sprague-Dawley rats (10 animals per group) were fed diet containing 0.5, 5, 50, or 500 ppm benzothiophene for 13 wk. Control animals were given rat feed plus vehicle (corn oil) only. No clinical signs of toxicity and neurobehavioral effects were observed using screening tests that included cage-side observations, righting reflex, open field activities, and forelimb and hindlimb grip strength. Elevated serum aspartate aminotransferase activity and bilirubin level were observed in highest dose females. Except for a statistically significant decrease in hematocrit in the highest dose males, benzothiophene exerted no marked effects on hematological parameters. Benzothiophene exposure did not result in alterations in hepatic alkaline phosphatase activity, or the typical hepatic phase I (aniline hydroxylase, ethoxyresorufin O-deethylase, pentoxyresorufin O-dealkylase, aminopyrine N-demethylase) and phase II (UDP-glucuronosyltransferase, glutathione S-transferase) drug-metabolizing enzyme activities. No significant elevation in urinary ascorbic acid, protein, and N-acetylglucosaminidase activity was detected in the treated animals. Peribiliary fibrosis was the most significant histological change and occurred in the liver of females in the 50 and 500 ppm groups. Mild epithelial hyperplasia in the renal pelvis was detected in the majority of 5 and 50 ppm females, with epithelial hyperplasia in the urinary bladder observed in the 50 ppm females. In males, increased incidence and severity of mild binucleation of hepatocytes and mild thickening of the basement membrane in kidney cortex were observed at 500 ppm. Benzothiophene was not detected in the urine of high-dose animals at the termination of the experiment. Based on the kidney, hepatic, and hematocrit changes, the no-observed-adverse-effect level (NOAEL) in the diet was determined to be 0.5 ppm (0.04 mg/kg/d) for females and 50 ppm (3.51 mg/kg/d) for males.

Function and expression of a novel rat salt-tolerant protein: evidence of a role in cellular sodium metabolism

Higher dietary salt intake in humans is associated with higher BP, but the BP response to NaCl, so-called salt sensitivity, is heterogeneous among individuals. It has been postulated that modifications in cellular cation metabolism may be related to salt sensitivity in mammalian hypertension. The authors have isolated a novel rat complementary DNA, called salt-tolerant protein (STP), that can functionally complement Saccharomyces cervisiae HAL1, which improves salt tolerance by modulating the cation transport system. On high-salt (8% NaCl) diets, both Dahl salt-sensitive and salt-resistant rats displayed an elevated BP and increased STP mRNA expression. Immunohistochemistry using an anti-rat STP antibody demonstrated the presence of STP immunoreactivity in the proximal tubules. In cells that transiently expressed STP, the intracellular [Na+]/[K+] ratio was higher than that in control cells. STP contains predicted coiled-coil and Src homology 3 domains, and shows a partially high degree of nucleotide identity to human thyroid-hormone receptor interacting protein. These results suggest that STP may play an important role in salt sensitivity through cellular sodium metabolism by mediating signal transduction and a hormone-dependent transcription mechanism.

Polarity, integrin, and extracellular matrix dynamics in the postischemic rat kidney

Acute renal failure (ARF) as a consequence of ischemic injury is a common disease affecting 5% of the hospitalized population. Despite the fact that mortality from ARF is high, there has been little improvement in survival rates over the last 40 years. The pathogenesis of ARF may be related to substantial changes in cell-cell and cell-extracellular matrix interactions mediated by beta1-integrins. On the basis of in vitro and in vivo studies, reorganization of beta1-integrins from basal to apical surfaces of injured tubular epithelia has been suggested to facilitate epithelial detachment, contributing to tubular obstruction and backleak of glomerular filtrate. In this study, we examine integrin and extracellular matrix dynamics during epithelial injury and repair using an in vivo rat model of unilateral ischemia. We find that, soon after reperfusion, beta1-integrins newly appear on lateral borders in epithelial cells of the S3 segment but are not on the apical surface. At later times, as further injury and regeneration coordinately occur, epithelia adherent to the basement membrane localize beta1 predominantly to basal surfaces even while the polarity of other marker proteins is lost. At the same time, amorphous material consisting of depolarized exfoliated cells fills the luminal space. Notably, beta1-integrins are not detected on exfoliated cells. A novel finding is the presence of fibronectin, a glycoprotein of plasma and the renal interstitium, in tubular spaces of the distal nephron and to a lesser extent S3 segments. These results indicate that beta1-integrins dramatically change their distribution during ischemic injury and epithelial repair, possibly contributing to cell exfoliation initially and to epithelial regeneration at later stages. Together with the appearance of large amounts of fibronectin in tubular lumens, these alterations may play a significant role in the pathophysiology of ARF.

Effect of colchicine on chronic ciclosporin nephrotoxicity in Sprague-Dawley rats

Thirty male Sprague-Dawley rats were given ciclosporin (Cs) orally, 15 mg/kg daily for 80 days. Fifteen served as positive controls, while the other 15 were given daily colchicine at a dose of 30 microg/kg in addition to Cs. Additional 15 rats were given olive oil only and served as negative controls. The animals were subjected every other week to laboratory assessment of serum creatinine, sodium, potassium, and Cs whole-blood trough levels; also urine samples were examined for creatinine, sodium, potassium, and protein concentrations. At the end point, the animals were sacrificed, and kidney tissue was examined for histopathological changes. Comparing negative control versus Cs-treated and Cs-plus-colchicine-treated rats, there were no significant differences in serum creatinine, creatinine clearance, and serum and urine values of sodium and potassium as well as urinary protein/creatinine ratios. Yet histopathological examination of kidney tissues showed focal tubular atrophy and interstitial fibrosis in inner medulla and inner stripe of the outer medulla in all Cs-treated animals and in only 1 of the colchicine-treated group, but in none of the negative controls. Histological changes in other kidney zones in different animal groups were minor and not different. From this study, we may conclude that colchicine is of protective value against chronic Cs nephrotoxicity in Sprague-Dawley rats.

Massive gross hematuria in a sickle cell trait patient with renal papillary necrosis. Conservative approach using a balloon ureteral catheter to tamponade the papilla bleeding

We report the case of a patient with heterozygous sickle cell trait presenting with massive gross hematuria. Ureteroscopy revealed bleeding from the tip of papilla of the inferior calica and allowed us to tamponade the bleeding with a balloon ureteral dilator set (Cook(R) Urology). We show the value of the endourological approach in the conservative management of these patients at high risk of recurrent hematuria.

Osteogenic protein-1 mRNA expression is selectively modulated after acute ischemic renal injury

Osteogenic protein-1 (OP-1) is a morphogenetic factor highly expressed in the kidney and involved in tissue repair and development. Homozygous OP-1-deficient mice die shortly after birth due mainly to arrest of renal growth and differentiation. Because postischemic injury involves several repair mechanisms, this study examined whether kidney OP-1 mRNA expression is modulated after ischemia. Acute ischemic renal injury was achieved in rats by unilateral clamping of the renal pedicle followed by reperfusion. Rats were killed at 3, 6, 12, 24, and 48 h and 7 d after reperfusion, and kidneys were microdissected and analyzed by histology and Northern and Western blots. Changes in OP-1 mRNA were determined by measuring the ratio of OP-1/glyceraldehyde 3-phosphate dehydrogenase signals for each OP-1 transcript (4.0 and 2.4 kb) from ischemic, opposite, and sham-operated rats. The OP-1 mRNA content for transcript 4.0 kb was fivefold lower in the whole ischemic kidney compared with that in sham animals 24 h after reperfusion. In the ischemic medulla, OP-1 mRNA was strikingly downregulated 20-fold when compared with the ischemic cortex. Results for transcript 2.4 kb and for the other time points were comparable. OP-1 mRNA expression was also affected in the opposite medulla compared with the sham medulla. However, only in the ischemic medulla was the relative OP-1 content significantly lower at all time points. Similar results were obtained when analyzing OP-1 protein by Western blot at 24 h after reperfusion. Seven days after reperfusion, the levels of OP-1 mRNA returned to baseline. In conclusion, kidney OP-1 mRNA and protein are selectively downregulated in the medulla after acute ischemic renal injury. OP-1 modulation may be a key element for kidney repair.

Sonographic renal findings in 20 dogs with leptospirosis

Abdominal ultrasound examinations of 20 dogs with confirmed leptospirosis were reviewed retrospectively for renal abnormalities. Three dogs had a normal ultrasound examination. The remaining 17 dogs had sonographic abnormalities of the kidneys. These abnormalities, seen either alone or in combination, included renalmegaly (n=10), pyelectasia (n=9), increased cortical echogenicity (n=15), perinephric effusion (n=5), and a medullary band of increased echogenicity (n=6). At our institution, the medullary band of increased echogenicity has only been seen in dogs with leptospirosis and may therefore be a specific sonographic sign for this disease.

Lipid peroxidation induced by shockwave lithotripsy

To determine the relation between high-energy shockwaves (HESW) and the presence of lipid peroxidation produces, juvenile pigs were subjected to shockwave lithotripsy (SWL). After lithotripsy, both treated and control kidneys were analyzed, along with urine samples collected before, during, and after SWL. Thiobarbituric acid-reactive substance (TBARS) and lipid-conjugated diene (CD) concentrations, used as markers for membrane lipid peroxidation, were determined in the kidney and urine samples. Significantly increased mean TBARS concentrations (146%) were associated with homogenates of lithotripsy-treated kidneys, 77.8 +/- 14.4 (SD) mmol/g v the controls, 31.4 +/- 14.9 mmol/g. Lithotripsy induction of lipid peroxidation products in the cortex, the gross damage site, and the respective medulla were also examined. In HESW-treated cortex samples, increased TBARS concentrations were seen--75.0 +/- 21.3 mmol/g--compared with untreated controls-- 45.2+/- 5.6 mmol/g--while increased CD concentrations (168%) were observed in the medulla of HESW-treated samples. No significant differences were observed in TBARS or CD concentrations in urine samples from control or treated kidneys, yet specific lipid hydroperperoxides were detected in the urine of HESW-treated kidneys. We conclude that HESW lithotripsy of swine kidneys is associated with increased lipid peroxidation products that may cause further cellular damage. Lipid peroxidation induced by SWL may be one of several mechanisms that lead to other potential bioeffects. Finally, analysis of specific lipid hydroperoxides in the urine of HESW-treated kidneys may serve as a noninvasive marker of renal injury after clinical SWL.

Renal AT1 receptor: computerized quantification in spontaneously hypertensive rats and DOCA-salt rats

To assess the involvement of angiotensin II (Ang II) in the regulation of blood pressure, we investigated the alterations of renal Ang II type 1 (AT1) receptors in two different models of hypertension; i.e., in spontaneously hypertensive rats (SHR) and deoxycorticosterone acetate (DOCA)-salt hypertensive rats by using the method for quantification of in vitro macro-autoradiography (ARG). In the SHR model, although the number of cortical AT1 receptors equaled that of Wistar Kyoto (WKY) rats at 4 and 12 weeks of age, the number of medullary AT1 receptors in the 4-week-old SHR animals was significantly lower than that in age-matched WKY rats, and increased by 12 weeks of age. The renal AT1 receptor number in DOCA-salt hypertensive rats was significantly higher than that in control rats. The amount of these receptors also increased with age in both DOCA-salt hypertensive rats and control rats. These findings indicate that the development of medullary AT1 receptors in early stages of hypertension in the SHR model differs from that in WKY rats or DOCA-salt hypertensive rats. This suggests that renal AT1 receptors may contribute to the hypertension seen in the SHR group. The renal AT1 receptors appear to be up-regulated in early stages of DOCA-salt-induced hypertension as well.

Sonographic findings in familial juvenile nephronophthisis-medullary cystic disease complex

PURPOSE

Familial juvenile nephronophthisis-medullary cystic disease complex (JN-MCD) is an autosomal inherited renal disease with insidious symptoms that ultimately progresses to renal failure. We describe the abnormal sonographic findings in JN-MCD at various stages of the disease in a Taiwanese family.

METHODS

We collected 8 cases in a family via 2 symptomatic index siblings. The affected members were 4 males and 4 females whose ages at diagnosis ranged from 1 to 39 years (mean, 16.8 years). Serial sonographic examinations were performed.

RESULTS

There were 4 abnormal findings: renal hyperechogenicity, poor corticomedullary differentiation, small kidney size, and corticomedullary cysts. Renal hyperechogenicity and poor corticomedullary differentiation were found in all cases. Renal cysts and reduced renal size sometimes appeared later, after the disease had progressed. Three cases had no visualized cysts.

CONCLUSIONS

Because abnormal renal sonographic findings can be seen long before the appearance of any clinical symptoms or signs, sonography is the best technique for diagnosing JN-MCD and for screening a patient's family.

Corticomedullary procollagen alpha1(IV) mRNA levels and localization after subtotal nephrectomy

The relationships between tubular hypertrophy/hyperplasia, procollagen alpha1(IV) mRNA levels, and the development of tubular basement membrane thickening were studied in male Sprague-Dawley rats subjected to subtotal renal ablation and sacrificed 2 or 15 days later. Tubular hypertrophy and hyperplasia were demonstrable at 2 days, however no increment in procollagen alpha1 (IV) mRNA levels was discerned at that time, demonstrating a dissociation between mRNA levels for classical type IV collagen and tubular enlargement. At 15 days, tubular procollagen alpha1(IV) mRNA levels did increase approximately 2-fold (p < 0.002), localizing predominantly in proximal tubules in the deep cortex and outer medullary stripe. At this time point, there was still no significant correlation to tubular enlargement, but there was a significant correlation to tubular basement membrane thickening (r = 0.89, p < 0.01). These studies demonstrated that an increase in mRNA for classical type IV collagen is not required for the development of hypertrophy, and that the increment is a better marker for matrix expansion than it is for hypertrophy.

A possible molecular basis of natriuresis during ischemic-reperfusion injury in the kidney

Ischemic renal injury is associated with increased fractional excretion of sodium, suggesting a Na+ reabsorption deficiency in renal tubules. To determine whether alterations in expression of the major Na+ transporter genes might contribute to the natriuresis that follows ischemic acute renal failure, the expression of these genes was analyzed in renal cortex and medulla after ischemic-reperfusion injury. Rats were subjected to 30 min of renal pedicle clamping and then sacrificed at 12, 24, or 48 h after reperfusion. Serum creatinine increased significantly at 12 and 24 h, indicative of acute renal failure, but decreased substantially by 48 h. mRNA levels for the NHE-3 Na/H exchanger of the proximal tubule, the apical Na-K-2Cl cotransporter of the thick ascending limb of Henle, the Na-Cl cotransporter of the distal convoluted tubule, the epithelial Na+ channel of the collecting duct, and the basolateral Na(+)-K(+)-ATPase were measured by Northern hybridization. NHE-3 mRNA decreased by approximately 75% at 12 h and remained suppressed at 24 and 48 h after reperfusion. Na-K-2Cl cotransporter mRNA decreased by approximately 88% at 12 h and remained suppressed at 24 and 48 h. Na-Cl cotransporter mRNA remained unchanged at 12 h, decreased by approximately 60% at 24 h, and returned to almost control levels at 48 h. mRNA levels for sodium channels (beta subunit) remained unchanged. Na(+)-K(+)-ATPase mRNA in the medulla decreased by approximately 35 to 40% at 12 and 24 h and by 70% at 48 h, whereas in cortex it decreased by only < 15% at 12 or 48 h after reperfusion. These results suggest that sharp reductions in expression of the NHE-3 Na/H exchanger and the apical Na-K-2Cl cotransporter are major factors in the natriuresis/diuresis that is one of the hallmarks of ischemic acute renal failure. Lasting suppression of these transporters, despite improvement in renal function, could contribute to the deranged NaCl and water excretion that often leads to volume depletion during recovery from ischemic acute renal failure.

Generalized AA-amyloidosis in Siberian tigers (Panthera tigris altaica) with predominant renal medullary amyloid deposition

Generalized amyloidosis with predominant renal medullary amyloid deposition was found in four closely related Siberian tigers (Panthera tigris altaica) suffering from end stage kidney diseases. Only minimal to mild amounts of amyloid were deposited in various organs outside the kidneys with individually variable organ involvement. The Congo red staining affinity of amyloid deposits was sensitive to potassium permanganate oxidation. The deposits were further characterized as being of the amyloid-A (AA) type by immunohistochemistry using the mouse monoclonal antibody mc4 directed against a conserved region of the human AA-protein. A combination of immunohistochemistry and Congo red staining was much more sensitive for the diagnosis of amyloid deposits than Congo red staining alone. With this combination, even minimal amyloid deposits were detected that had been missed in the first reading using Congo-red-stained slides alone. Since no common primary cause was identified, the amyloidosis was classified as idiopathic generalized AA-amyloidosis with a potential familial predisposition.

Serotonin (5-HT1A-receptor) agonist-induced collecting duct vacuolation and renal papillary necrosis in the rat

General anxiety in humans is treated with azaspirodecanedions, which act through a reduction of serotonin transmission. Ipsapirone also represents a serotonin (5-HT1A) receptor agonist and was under development as an anxiolytic drug. Histopathologic evaluation of animal experiments revealed cellular swelling and/or vacuolation of renal papillary and medullary collecting duct (MCD) epithelium in rats but not in dogs or mice. The changes ensued already after 1 wk of dosing and were first localized in the inner MCDs. Longer treatment periods showed that these changes proceeded from proximal to distal, approaching the papillary collecting ducts. The changes were most likely the result of altered hemodynamics in the papillary tip. Swelling resulted in partial or total papillary necrosis in some cases. Furthermore, rats treated with ipsapirone showed a sharp and transient rise in urinary endothelin excretion. Concomitantly, urinary PGE2 levels were elevated. In contrast, no elevated levels of endothelin were detected in urine samples of patients from a volunteer study, leading to the conclusion that the human kidney is not susceptible to the ipsapirone-induced alterations seen in the collecting ducts of rats.

An isolated case of nephronophthisis: medullary cystic disease without typical onset

A 16-year-old girl with renal failure was transferred to our hospital for an extensive renal examination. Computerized tomography and ultrasonography showed multiple small cysts throughout the medulla of both kidneys. Histological findings revealed tubular atrophy and dilatation and marked periglomerular fibrosis, all of which were compatible with nephronophthisis. Her development and growth were normal. A prior urinalysis, as well as her symptoms and family history were not helpful for making a diagnosis. As early diagnosis of nephronophthisis is difficult in some cases, more detailed screening is needed for children and adolescents.

Inhibition of myo-inositol transport causes acute renal failure with selective medullary injury in the rat

Myo-inositol is a major compatible osmolyte in the renal medulla that is accumulated under hypertonic conditions via the Na+/myo-inositol cotransporter (SMIT). We have recently reported that SMIT is predominantly present in the thick ascending limb of Henle (TAL) and is strongly induced by acute NaCl loading, suggesting an important role of myo-inositol in this nephron segment. In the present study, we sought to examine in vivo effects of inhibition of myo-inositol transport using a transport inhibitor, 2-O, C-methylene-myo-inositol (MMI). Intraperitoneal injection of MMI caused acute renal failure in the rats. Serum creatinine and urea nitrogen were significantly increased 12 hours after MMI injection. Morphologic study revealed that the tubular cells were extensively injured in the outer medulla. A considerable number of the tubular cells were injured in the cortex as well. Immunohistochemical study for Tamm-Horsfall protein (THP), which was used for identification of the TAL cells, showed that THP-positive cells were predominantly injured. The tubular injury apparently appeared to worsen when high concentration of NaCl was injected with MMI. Administration of myo-inositol prevented acute renal failure and improved the tubular injury after MMI injection. Furthermore, supplementation of betaine, another osmolyte in the TAL cells, partially prevented the toxic effects of MMI. These results suggest that myo-inositol play a crucial role in the TAL regarding osmoregulation of the cells.

Neonatal cholestasis and focal medullary dysplasia of the kidneys in a case of microcephalic osteodysplastic primordial dwarfism

We report on a male infant who presented with intrauterine growth retardation, severe postnatal failure to thrive, microcephaly, facial dysmorphism, and skeletal dysplasia. The clinical and radiological findings are consistent with former descriptions of microcephalic osteodysplastic primordial dwarfism (MOPD) type I/III. In addition to previously published features, multiple fractures of the long bones, severe neonatal cholestasis, and histological dysplasia of the kidneys were found. The boy died at the age of 8 months. The new finding of focal renal medullary dysplasia further supports the hypothesis of a basic defect in tissue differentiation in the pathogenesis of this rare condition.

Effect of papillotoxic agents on expression of cyclooxygenase isoforms in the rat kidney

Inhibition of renal vasodilatory prostaglandins (PGs) and secondary ischemia due to inhibition of cyclooxygenase (COX) activity has been suggested as a possible mechanism for development of analgesic-related renal papillary necrosis (RPN) in rats. Recently, it has been shown that COX exists in two related but unique isoforms, COX-1 and COX-2. It is unclear what potential roles these isoforms play in the maintenance of blood flow in the renal papilla or genesis of RPN. We evaluated the effect of 2 papillotoxic agents, including a nonsteroidal anti-inflammatory drug, indomethacin, and a chemical agent, 2-bromoethanamine hydrobromide (2-BEA), on COX-1 and COX-2 in the renal papilla as a means of assessing what changes occur in the expression of these isoforms during the development of RPN. Female Wistar rats approximately 10-17 wk old were treated with either indomethacin (75 mg/kg, single dose, or 10 mg/kg/day for 5 days) or 2-BEA (100 mg/kg/day for 4 days) to create lesions of RPN. In this study, a single 75-mg/kg dose of indomethacin did not cause light microscopic changes of RPN. However, RPN was observed in animals administered indomethacin at 10 mg/kg/day for 1 wk or 2-BEA for 5 days. The immunohistochemical analyses of kidneys showed that both COX-1 and COX-2 were present in the renal papilla of control rats. In animals treated with indomethacin (75 mg/kg), a slight to moderate decrease in both isoforms was observed in essentially normal renal papillary cells within 2 hr, that was followed by an increase in COX-2 immunoreactivity in the renal papilla, macula densa, and thick ascending limbs (both 10- and 75-mg/kg animals). This COX-2 immunoreactivity was greatest in animals with concomitant indomethacin-induced gastrointestinal injury, suggesting a possible role of inflammatory cytokines in COX-2 induction. No changes in the expression of COX isoforms in the intact papilla occurred as a result of 2-BEA; however, cells undergoing degeneration and necrosis lost immunoreactivity to both COX isoforms. The possible mechanism that leads to an initial decrease in COX immunoreactivity in indomethacin-treated animals is not known; however, a reversible ultrastructural change in the papillary cells cannot be ruled out. This decrease in COX isoforms in the renal papilla may contribute to the development of RPN through the loss of vasodilatory PGs.

2-Hydroxy-4-glutathion-S-yl-17beta-estradiol and 2-hydroxy-1-glutathion-S-yl-17beta-estradiol produce oxidative stress and renal toxicity in an animal model of 17beta-estradiol-mediated nephrocarcinogenicity

Chronic exposure of male Syrian hamsters to a variety of estrogens has been linked with a high incidence of renal carcinoma. The basis of this species and tissue specificity remains to be resolved. We have recently shown that (i) 17beta-estradiol is nephrotoxic in the hamster in a manner dependent upon the activity of gamma-glutamyl transpeptidase and (ii) 17beta-estradiol is metabolized to a variety of catechol estrogen glutathione conjugates (Butterworth et al., Carcinogenesis, 18, 561-567, 1997). We report that the catechol estrogen glutathione conjugates exhibit redox properties similar to those of the catechol estrogens, and maintain the ability to generate superoxide radicals. Administration of 2-hydroxy-4-glutathion-S-yl-17beta-estradiol or 2-hydroxy-1-glutathion-S-yl-17beta-estradiol (0.27-5.0 micromol/kg) to Syrian hamsters, produces mild nephrotoxicity. Repeated daily administration of 2-hydroxy-4-glutathion-S-yl-17beta-estradiol causes a sustained elevation in urinary markers of renal damage and in the concentration of renal protein carbonyls and lipid hydroperoxides. Catechol estrogen oxidation and conjugation of glutathione in the liver, followed by the selective uptake of the redox active conjugates in tissues rich in gamma-glutamyl transpeptidase may contribute to 17beta-estradiol-induced renal tumors in the hamster.

Mechanism of fibrosis in experimental tacrolimus nephrotoxicity

The clinical use of tacrolimus (FK506) is limited by nephrotoxicity. The pathogenesis of fibrosis in chronic FK506 nephrotoxicity remains unknown. Because transforming growth factor (TGF)-beta plays a key role in the fibrogenesis of many diseases, including cyclosporine nephrotoxicity, we studied a salt-depleted rat model of chronic FK506 nephropathy in which clinically relevant FK506 blood levels are obtained and which shows similarities to the lesions described in patients receiving FK506. Pair-fed rats were treated with either FK506 (1 mg/kg/day s.c.) or an equivalent dose of vehicle and were killed at 7 or 28 days. Characteristic histologic changes of tubular injury, interstitial fibrosis, and arteriolopathy developed in FK506-treated rats at 28 days and were accompanied by worsening kidney function, decreased concentrating ability, and enzymuria. FK506-treated kidneys had a progressive increase in the expression of TGF-beta1 and matrix proteins (biglycan, tenascin, fibronectin, and type I collagen). This effect seems to be specific because the expression of type IV collagen, a basement membrane collagen, was not affected. Matrix deposition was present mostly in the tubulointerstitium and vessels in accordance with the FK506 chronic lesion. The expression of plasminogen activator inhibitor-1, a protease inhibitor influenced by TGF-beta, followed TGF-beta1 and matrix proteins, suggesting that the fibrosis of chronic FK506 nephropathy likely involves the dual action of TGF-beta1 on matrix deposition and degradation. Since both peripheral and tissue renin expression were elevated with FK506, the renin-angiotensin system may play a role in the pathogenesis of this condition.

Endoscopic mapping of renal papillae for Randall's plaques in patients with urinary stone disease

PURPOSE

Papillary "Randall's plaques" are theorized to act as nidi for urinary stone formation. The aim of this study was to document the presence, pattern and distribution of Randall's plaques in patients undergoing endoscopic procedures for urinary stone disease.

MATERIALS AND METHODS

Patients undergoing either ureteroscopy or percutaneous nephroscopy for removal of urinary stones underwent endoscopic mapping of accessible calices. These patients were compared to a smaller group of patients undergoing endoscopic procedures for conditions unrelated to urinary stone disease. In patients found to have papillary plaques the presence, location and pattern of plaques were recorded. Plaque formation was correlated with patient age and sex, and primary composition of extricated stone.

RESULTS

Endoscopic evidence of papillary Randall's plaques was found in 74% of 57 patients having ureteroscopic (21) or percutaneous (36) stone removal. Of 7 patients having endoscopic procedures for conditions unrelated to urinary stone disease 3 (43%) had evidence of papillary plaques. Plaques were found uniformly throughout all calices and most commonly diffusely scattered over the papillary surface. There was no correlation between patient age or sex and the presence of plaques. The incidence of plaques varied with the primary composition of extracted stones, and was 100% for calcium phosphate and uric acid, 88% for calcium oxalate, 33% for cystine and 20% for struvite. The incidence of papillary plaques was significantly more common in patients with calcium oxalate (88 versus 43%, p = 0.023) and calcium phosphate stones (100 versus 43%, p = 0.009) than patients without a history of urinary stone disease.

CONCLUSIONS

The endoscopic incidence of papillary Randall's plaques in patients with urolithiasis varies with the primary composition of formed urinary stones. Randall's plaques are found in the majority of patients with calcium urinary stone disease. Our findings suggest that the presence of papillary plaques is associated with calcium nephrolithiasis and may contribute to the pathogenesis of calcium urinary stones.

Regional renal nitric oxide release in stroke-prone spontaneously hypertensive rats

Diminished nitric oxide (NO) production has been implicated in the pathogenesis of salt-sensitive hypertension. We questioned whether such a defect is responsible for the malignant hypertension and nephrosclerosis in stroke-prone spontaneously hypertensive rats (SHRSP) fed a high-salt/stroke-prone diet (S) versus a regular diet (R). NO release from 30-minute incubates of cortex and outer and inner medulla were studied in SHRSP at 10, 12, and 16 weeks of age on the S diet versus R diet. SHRSP-S (n=16) exhibited a marked age-dependent increase in NO release, especially in the cortex. Increases were only modest in SHRSP-R (n=21). At 16 weeks, cortical NO was 93+/-25 versus 6+/-1 pmol/mg tissue in SHRSP-S versus SHRSP-R (P<.001). Immunohistochemical staining increased mostly for neuronal, slightly for endothelial, and negligibly for inducible isoforms of NO synthase and was predominantly in the cortex of SHRSP-S versus SHRSP-R. Despite similar hypertension in SHRSP-S versus SHRSP-R (mean arterial pressure, 174+/-7 versus 177+/-2 mm Hg), malignant nephrosclerosis was seen only in SHRSP-S, affecting 22+/-6% of glomeruli and 23+/-4 vessels per 100 glomeruli by 16 weeks. N omega-nitro-L-arginine (15 mg/kg per day) in SHRSP-S (n=6) abrogated the increase in cortical NO but further augmented the hypertension and accelerated lesion development. Wistar-Kyoto rats at 16 weeks on the R diet (n=8) had NO levels similar to those of SHRSP-R, showed increased cortical NO to only 28+/-10 pmol/mg on the S diet (n=9) (P<.05 versus SHRSP-S), but remained normotensive and lesion-free. We conclude that hypertension and lesion development in SHRSP are not due to deficient renal NO. Accelerated onset of malignant nephrosclerosis by NO synthase inhibition suggests that NO is protective in these animals, mitigating the effects of hypertension and S diet on renal pathology.

X-linked hypophosphatemia: normal renal function despite medullary nephrocalcinosis 25 years after transient vitamin D2-induced renal azotemia

Nephrocalcinosis (NC) detected by ultrasound is a recognized abnormality for some patients with X-linked hypophosphatemia (XLH) who received vitamin D2 and inorganic phosphate therapy, but is commonly observed in XLH patients treated with 1,25-dihydroxyvitamin D3 and inorganic phosphate supplementation. Nevertheless, long-term follow-up of kidney function in XLH patients with NC detected ultrasonographically has not been reported. We investigated two women with XLH, ages 31 (patient 1) and 39 (patient 2) years, each of whom had suffered at least one documented episode of vitamin D2-induced hypercalcemia and renal azotemia during childhood. Patient 2 had also been treated with inorganic phosphate. No medications for XLH had been taken during adulthood. Renal ultrasonography at our institution demonstrated marked bilateral medullary NC in both women. No other explanation was found for their NC that apparently occurred several decades earlier from medical therapy for XLH. Detailed studies (including creatinine clearance, beta2-microglobulin excretion, and fasting urinary osmolality and acidification) revealed no impairment of kidney function in either patient. Our findings indicate that subradiographic medullary NC acquired during medical therapy for XLH may persist for decades, but with no adverse renal sequelae. Definitive (long-term) assessment of kidney function in the XLH population with NC, however, will be necessary to fully understand the risk of current medical treatment for this most common heritable form of rickets.

Lobar dysmorphism of the kidney: report of two cases and review of the literature

Lobar dysmorphism is one of a number of normal anatomic variants that may simulate renal mass lesions on cross-sectional imaging. The authors report the US and CT features in two patients with this unusual entity.

Exaggerated natriuresis in transgenic (mRen2)27 rats

BACKGROUND

Hypertension features an exaggerated natriuresis after acute volume expansion. In humans, the degree of exaggerated natriuresis appears to be correlated inversely to the level of angiotensin (Ang) II.

OBJECTIVE

To test the hypothesis that the degree of exaggerated natruresis is correlated to the level of Ang II by studying two rat models, transgenic rats (TGR) with and extra renin gene (TGR mRen2)27 and desoxycorticosterone acetate (DOCA)-salt rats, in comparison with Sprague-Dawley Hannover (SDH) rat controls.

METHODS

All of the rats were uninephrectomized for 1 month. DOCA-salt rats were implanted with a DOCA pallet and drank 1% saline. Rats were anesthetized and their left kidneys were instrumented with renal sympathetic nerve activity (RSNA) electrodes and laser-Doppler cortical and medullary flow probes. The glomerular filtration rate, diuresis, and natriuresis were measured for 120 min after sodium loading (5% body weight 0.9% saline administered during 3 min). Kidneys were examined histologically.

RESULTS

The blood pressure in TGR and DOCA-salt rats was 40-50 mmHg higher than that in SDH rats, and decreased briefly after volume expansion for all groups. The diuresis and natriuresis of TGR and DOCA-salt rats were greater than those of SDH rats. The medullary blood flow increased and the cortical blood flow in SDH decreased, whereas the cortical blood flow in TGR and DOCA-salt rats remained high. The RSNA in rats of all groups decreased; however, this decrease was greater in SDH than it was in TGR and DOCA-salt rats. The histology was affected most severely for the DOCA-salt rats.

CONCLUSIONS

Exaggerated natriuresis occurred in hypertensive rats regardless of their Ang II status. Both strains were characterized by a smaller decrease in RSNA and a preserved cortical blood flow in the face of volume expansion. These data do not support the notion that exaggerated natriuresis is a function of renin-level suppression for rats.

Renal accumulation and distribution of hyaluronan after ureteral obstruction

In a unilateral ureteral obstruction model, a progressive accumulation of hyaluronan (HA) was observed in the renal papilla during the first 11 days of obstruction, after which the amount of HA decreased until the last day of observation, i.e. day 22. The initial accumulation of HA in the obstructed kidney probably reflects the attempts of the kidney to maintain osmotic balance. Consequently, when filtration ceases, HA synthesis decreases and the concentration of HA falls. In the papilla of the contralateral kidney, that had not been exposed to any mechanical damage, the HA content was found to vary in a similar way to that in the obstructed kidney. The explanation for this could be that the mesenchymal cells within the papilla increase their production of HA in order to meet the requirements of increased function necessary to also shoulder the function of the damaged kidney. In short similar variations in the HA content of the renal papilla was observed in both healthy and obstructed kidneys in a unilateral ureteral obstruction model.

Combined kidney-pancreas and parathyroid transplantation: a case report

We report the first successful multiorgan kidney-pancreas and parathyroid tissue transplant in a patient with autoimmune polyglandular syndrome and medullary cystic disease. Successful transplantation included quadruple drug induction therapy consisting of antithymocyte globulin, azathioprine, cyclosporine and prednisone. All three grafts are functioning 2 yr after transplantation.

Bilateral xanthine nephrolithiasis in a dog

Xanthinuria is an uncommon metabolic disorder clinically manifested as urolithiasis. There are two forms of the disease, congenital and iatrogenic. The former was diagnosed in a four-year-old dachshund bitch. The patient was presented with signs of terminal chronic renal failure. Urine was bacteriologically sterile with massive amorphous crystalluria. Bilateral nephrolithiasis was diagnosed at necropsy. The kidneys were shrunken with marked atrophy of the renal cortex and medulla. Infrared spectrometry revealed that the stones comprised 100 per cent xanthine. Later, two of the patient's siblings were examined for urine xanthine content; both showed higher concentrations of xanthine than a control dog. The described case is compared with seven known published cases of congenital xanthinuria.

Role of platelet-activating factor in two-kidney, one-clip hypertension

BACKGROUND

Platelet-activating factor (PAF) is a bioactive phospholipid which is a potent hypotensive agent. To investigate the role of PAF in renovascular hypertension, we determined the PAF concentration and its production level assessed by the activity of cholinephosphotransferase (CPT) in renal tissue and examined the effect of a PAF antagonist on the mean arterial pressure (MAP) in control and two-kidney with one clipped (2K1C) hypertensive rats.

MATERIALS AND METHODS

The concentration of PAF and CPT in the renal medulla and cortex were determined by radioassay. Also, the effect of a PAF antagonist, CV-6209, on MAP was also examined in both 2K1C hypertensive and normal control rats.

RESULTS

The PAF concentration and CPT activity were significantly higher in the medulla than in the cortex in both 2K1C hypertensive and normal control rats, and both values in the medulla were also significantly higher in the clipped kidney than in the contralateral unclipped kidney or in control rat kidneys. We also observed a significant negative correlation between the PAF concentration in the medulla, and the medulla weight in the clipped kidney of 2K1C hypertensive rats. Infusion of the PAF antagonist, CV-6209, did not affect MAP in 2K1C hypertensive rats, but was significantly increased (P < 0.05) in control rats.

CONCLUSIONS

These findings suggest that PAF, whose production is induced by renal ischemia due to renal artery stenosis, plays an important role in the renomedullary vasodepressor system, but the effect of PAF as a vasodilator in the peripheral vessels is limited in 2K1C hypertension.

Late occurrence of cysts in autosomal dominant medullary cystic kidney disease

Medullary cystic kidney disease (MCD) is characterized by multiple renal cysts at the corticomedullary boundary area, by autosomal dominant inheritance, and by onset of chronic renal failure in the third decade of life. We report on a family with three affected individuals of both sexes in two generations presenting with end-stage renal failure at age 22-31 years. Primarily diagnoses considered included unclassified hereditary nephropathy and autosomal dominant polycystic kidney disease. Careful evaluation of all findings, initiated after investigation of renal morphology with CT, revealed features characteristic for MCD and led to the final diagnosis of MCD. We conclude that MCD is an important differential diagnosis for polycystic kidney disease in young adults with end-stage renal failure. Establishing the correct diagnosis has considerable impact for genetic counselling.

Age of onset of streptozocin diabetes determines the renal structural response in the rat

Prepubertal years of insulin-dependent diabetes mellitus are protected from the nephropathic effects of this disease, yet this effect of immaturity has not been investigated in an animal model. Male Munich-Wistar rats were made diabetic with streptozocin at two ages: weanling (approximately 4 wk) and pubescent (approximately 10 wk). After 5 wk of untreated diabetes, weanling diabetic animals showed relatively greater growth of the medulla, whereas relative proportions of these areas were constant in the older animals. Glomerular volume increased by approximately 35% in older diabetic animals, but no glomerular enlargement was demonstrated in weanling rats with diabetes. Glomerular ultrastructure was not significantly altered during the short course of this study. The renal structural response to diabetes is age-dependent in the rat, with prepubertal animals protected from glomerular hypertrophy. Longer studies are needed to see if these differences will eventually parallel those demonstrated in patients with onset of diabetes before and after puberty. This model may ultimately prove to be valuable in determining the mechanism via which prepubertal kidneys are protected from the nephropathic effects of insulin-dependent diabetes mellitus.

Altered cell differentiation and proliferation in mice lacking p57KIP2 indicates a role in Beckwith-Wiedemann syndrome

Mice lacking the imprinted Cdk inhibitor p57(KIP2) have altered cell proliferation and differentiation, leading to abdominal muscle defects; cleft palate; endochondral bone ossification defects with incomplete differentiation of hypertrophic chondrocytes; renal medullary dysplasia; adrenal cortical hyperplasia and cytomegaly; and lens cell hyperproliferation and apoptosis. Many of these phenotypes are also seen in patients with Beckwith-Wiedemann syndrome, a pleiotropic hereditary disorder characterized by overgrowth and predisposition to cancer, suggesting that loss of p57(KIP2) expression may play a role in the condition.

Cytopathology of renal collecting duct carcinoma in urine sediment

Two cases of histologically, immunohistochemically, and ultrastructurally confirmed collecting duct carcinoma of the kidney (CDCK) with positive urine cytology are reported. The patients' urine sediments showed malignant glandular cells in sheets with defined, variable, granular cytoplasm and oval, hyperchromatic nuclei containing micro- or macronucleoli. The cytologic differential diagnosis of CDCK is briefly discussed.

Medullary injury in the ageing rat kidney: functional-morphometric correlations

Urinary concentrating ability decreases with age in both humans and animals. This phenomenon is not yet clearly explained or corroborated by morphological findings, often focused on glomerular changes. In rats aged 5-22 months, semi-quantitative and quantitative morphometric analysis was performed to score cortical and medullary changes. Morphological-data were related to renal functional parameters. Three stages of tubulo-interstitial injury were observed: minimal findings (stage I); mild fibrosis with atrophy and casts in medullary thick ascending limbs (stage II): extensive fibrosis and atrophy with large cast formation (stage III). Maximal urinary osmolality decreased in correlation with the stage of tubulointerstitial injury (r = -0.8, P < 0.001), from 3735 mosmol L-1 at stage I to 2807 at stage II and 1567 at stage III. A dissociation was observed in the rate of progression with age between tubulointerstitial injury and glomerular sclerosis. Whereas sclerosis was observed in only 2-3% of glomeruli at both stages I and II of tubulointerstitial injury, damage to thick ascending limbs significantly increased from 2% of tubules at stage 1 to 11% at stage II (P < 0.002). At stage III, both extensive glomerular sclerosis (53%) and tubular injury (32%) were present. Uninephrectomy accelerated both morphological injury and functional compromise. We conclude that, in the early stages of renal ageing, injury to medullary tubules may be more prevalent than injury to glomeruli and could be responsible for the reduction in concentrating ability.

Renal microcirculation and tissue damage during acute ureteral obstruction in the rat: effect of saline infusion, indomethacin and radiocontrast

Radiocontrast agents and nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used for the diagnosis and treatment of renal colic. We studied their impact during unilateral acute urinary outflow obstruction upon renal microcirculation and parenchymal integrity. Laser-Doppler and ultrasonic regional flow measurements demonstrated selective decline of outer medullary blood flow by 23 +/- 2% during an acute increase of intra-pelvic pressure to 50 to 55 cm H2O (N = 28, X +/- SEM, P < 0.01). In rats preconditioned with indomethacin, this manipulation reduced medullary blood flow by 50 +/- 4% (N = 16, P < 0.01 vs. obstruction alone), with cortical and total renal blood flow declining by 18 +/- 4% and 16 +/- 2%, respectively (P < 0.01). Unilateral obstruction alone for 24 hours in intact rats resulted in injury (hemorrhage and necrosis) to the papilla and fornix (formed laterally by inner stripe and medially by the inner medulla). These changes were detected as early as 30 minutes after ureteral ligature by staining for fragmented nuclear DNA (TUNEL). Mild damage of thick ascending limbs (mTALs) was associated with substantial medial fornix injury. Indomethacin markedly increased mTAL injury in obstructed kidneys, but attenuated inner medullary damage, both in the medial border of the urinary space and at the papilla. This latter protective effect, probably mediated by the decrease in intrapelvic pressure, was blunted by concomitant intravenous fluid load. Contrast media (iothalamate) and L-NAME (N omega nitro-L-arginine methyl ester) both augmented inner stripe and inner medullary damage in hydronephrotic kidneys. In rats concomitantly subjected to radiocontrast, indomethacin and L-NAME (an acute renal failure protocol, J Clin Invest 94:1069, 1994), unilateral obstruction augmented inner stripe hypoxic damage (65 +/- 6% vs. 24 +/- 11% of mTALs in contralateral kidneys, N = 7, P < 0.01). Injury was maximal at the fornix (93 +/- 6% vs. 39 +/- 14% of mTALs in the mid-inner stripe, P < 0.01) and extended to the outer stripe and medullary rays. Thus, in the rat acute ureteral obstruction alters medullary blood flow and within 24 hours produces medullary damage in both forniceal and inner medullary locations, that is exacerbated by concomitant measures which limit medullary oxygenation. Contrast studies, forced hydration and NSAIDs for renal colic are potentially harmful and their use should be re-evaluated.

Effects of renal papillary-medullary lesion on the antihypertensive effect of furosemide and development of salt-sensitive hypertension in Dahl-S rats

To test the hypothesis that the long-term antihypertensive action of furosemide is mediated by a renomedullary vasodepressor substance, we measured mean arterial pressure (MAP) by radiotelemetry in Dahl-S rats with either intact or bromoethylamine-induced (BEA, 100 mg/kg i.p.) lesion of the renal papilla and medulla. Seven days of recovery after BEA administration, the rats diet was changed from 1 to 4% NaCl, and during days 8 to 31, rats were randomized to daily treatment with placebo or furosemide (50 mg/kg p.o.). Then furosemide treatment was stopped and the rat food was changed to 1% NaCl diet. After a 10-day wash-out period, renal function was measured. BEA produced a rapid (within min) and sustained increase in MAP which was accelerated during 4% NaCl diet. Furosemide prevented 4% NaCl-induced hypertension in both rats with intact kidneys and in rats with BEA-induced renal papillary-medullary lesion. A significant decrease in renal plasma flow (-34%) and glomerular filtration rate (-40%) was observed in all BEA-treated rats independent of previous furosemide treatment. In response to an i.v. load of isotonic saline (10% body weight), rats with renal papillary-medullary lesion had an impaired ability to excrete sodium. Histological examination showed that BEA-treated rats had severe lesions of the renal papilla and medulla, with light-to-moderate changes in the renal cortex. It is concluded that the antihypertensive effect of furosemide is not mediated by a renomedullary vasodepressor substance. The accelerated NaCI-sensitive hypertension in rats with BEA-induced renal papillary-medullary lesion is related to an impaired ability to excrete excess NaCl.

1H NMR spectroscopic and histopathological studies on propyleneimine-induced renal papillary necrosis in the rat and the multimammate desert mouse (Mastomys natalensis)

The renal papillary toxin, propyleneimine (PI), was administered at 20 or 30 microliters/kg i.p. to male Sprague Dawley (SD) rats (n = 5), Fischer 344 (F344) rats (n = 4), and to multimammate desert mice (Mastomys natalensis, n = 4). Urine was collected at time points up to 4 days p.d. and the toxicological response of the different animal models to PI compared using 1H NMR spectroscopy of urine, renal histopathology, and urinary assays for alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and gamma-glutamyl transpeptidase (gamma GT). The renal papillae of both F344 and SD rats showed extensive necrotic lesions 4 days post-dosing and in some cases sloughing of the papilla. However, only slight renal papillary necrosis (RPN) was observed in Mastomys treated with 20 microliters/kg PI and, although slight to moderate damage was observed at 30 microliters/kg, PI-treated Mastomys showed substantially less RPN than either group of PI-treated rats. 1H NMR urinalysis showed that PI treatment caused a decrease in the urinary concentrations of succinate (0-24 hr p.d.) and citrate (24-48 hr p.d.) and an increase in creatine (0-48 hr p.d.) in all animal models. Trimethylamine-N-oxide (24-48 hr) and 2-oxoglutarate concentrations decreased initially following the administration of PI and then rose above control levels. The 1H NMR-detected urinary biochemical effects of PI in all three models were similar. However, taurine concentrations were elevated in the urine of Mastomys following PI treatment, perhaps indicating a degree of liver damage, whereas taurinuria was not seen in either SD or F344 rats. These observations are discussed in relation to the potential mechanism of PI-toxicity.

Glomerular volume in congestive cardiac failure

Glomerular volume has been reported to be increased in patients with congenital cyanotic heart disease and cor pulmonale; however it has not been systematically studied in patients with congestive cardiac failure (CCF). Glomerular volume was therefore measured by point-counting serially sectioned glomerular profiles of 25 randomly selected glomeruli using the Cavalieri principle in autopsy specimens from 8 patients dying from CCF and 6 age-matched controls with no renal or cardiac pathology. Mean glomerular volume was not different between patients dying from CCF and controls, 2.49 (0.21) vs. 2.25 (0.26) x 10(6) microm3, and the distribution of individual glomerular volumes was similar in the two groups. We conclude that severe CCF is not associated with significant glomerular enlargement and that the previously reported glomerular enlargement in cyanotic heart disease is likely to be mediated through hypoxemia.

Ultrasonographic evaluation of renal size in dogs with acute allograft rejection

The purpose of this study was to determine the best method to ultrasonographically monitor renal size changes associated with acute allograft rejection in dogs. Qualitative changes in renal cortical and medullary echogenicity were also evaluated, although this was not a major focus of the study. Four unrelated, mixed-breed dogs underwent bilateral nephrectomies and heterotopic renal allograft transplantation. Ultrasound examinations of transplanted kidneys were initiated at 3 days after surgery and continued at 2-3 day intervals until death (38 +/- 2 days). Ultrasound measurements of kidney length, width, height, cross-sectional area, and estimated volume were used to assess relative changes in renal size associated with transplantation and rejection. Transplanted kidneys had a rapid increase in volume and cross-sectional area that averaged 103% and 83% above baseline levels, respectively, by 17 days after transplantation. The increased size was attributed to a combination of hypertrophy and acute rejection, the latter of which was confirmed at postmortem. Kidney volume decreased to approximately 35% above baseline volume by day 34 as rejection became more advanced. Qualitative changes associated with rejection included medullary enlargement with decreased echogenicity early in the study, followed by increased cortical thickness and echogenicity with poor cortical medullary definition in the latter stages of the survival period. It was concluded that relative changes in renal allograft size can be easily monitored with ultrasound. In regard to linear measurements, changes in renal width were more pronounced than changes in height or length with acute rejection. Therefore measurements that incorporate the width, namely volume or cross-sectional area, appear to be the most sensitive for monitoring changes in allograft size. Renal cross-sectional area measurements are preferred because they are simple to perform using the automated calculation capability of most newer ultrasound units.

Relationship between MRI and morphometric kidney measurements in diabetic and non-diabetic rats

The aim of the present study was to determine the applicability of magnetic resonance imaging (MRI) as a non-invasive measure of kidney volume in vivo in diabetic and non-diabetic rats. Magnetic resonance, T1 weighted Spin Echo, images were obtained after injection of contrast in anesthetized control (N = 14) and hyperglycemic streptozotocin (STZ)-diabetic rats (N = 14). On MRI imaging the total kidney, cortex, medullary and pelvic volumes were calculated. Immediately after MRI measurements the left kidneys were removed before weighing either as a clamped kidney weight (that is, the kidney containing blood and urine) or as a wet kidney weight (the kidney drained of blood and urine), while the right kidneys were perfusion-fixed for morphometric measurements. On thin kidney slices obtained from perfusion-fixed kidneys the cortex, medullary and pelvic fractions were measured and subsequently the cortex, medulla and pelvic volumes were calculated. The cortical volume was measured according to three different approaches. The corticomedullary boundary was defined either to the arcuate arteries, to a curved line following the glomeruli, or to a line at the top of the medullary rays. Both in control and diabetic rats, MRI measured kidney volumes were similar to the volume of perfusion-fixed kidneys, while the clamped kidney weight, and in particular the wet kidney weights, were smaller than the MRI obtained volumes. Good agreement was found between the MRI measured cortex and medulla volumes when the cortex was defined to the top of the medullary rays in the morphometric analysis. In conclusion, the present study demonstrates that MRI allows a reliable non-invasive estimate of renal morphology at a macroscopic level in both diabetic and non-diabetic rats.

Magnetic resonance imaging of the kidney in hemorrhagic fever with renal syndrome: its histopathologic correlation

We present 2 cases of magnetic resonance imaging in hemorrhagic fever with renal syndrome and their histopathologic findings. The low signal intensities along the renal outer medulla in T2-weighted images are persistent ex vivo as well as in vivo, and these are the radiologic counterpart of medullary congestion and hemorrhage. We will discuss the significance of the imaging in the fields of the medical renal disease such as acute renal failure and review the mechanisms of acute renal failure in hemorrhagic fever with renal syndrome.

Nephrogenesis and renovascular development in angiotensinogen-deficient mice

Angiotensinogen-deficient mice provide a model to examine the roles of angiotensin II as a renal growth factor in vivo. We monitored nephrogenesis and renovascular development in angiotensinogen-deficient mice from Embryonic Day 13 (E13) to 4 weeks after birth. Northern analysis of homozygote (Atg-/-) mice confirmed the absence of angiotensinogen mRNA in the liver and the kidneys. Embryonic kidneys in Atg-/- mice from E13 to E18 exhibited active nephrogenesis, as also observed in Atg+/- mice and Atg+/+ mice. Furthermore, metanephroi harvested at E12 from Atg-/- embryos showed branching morphogenesis of ureteric bud and tubulogenesis similar to metanephrol from Atg-/- embryos grown with exogenous angiotensin II in serum-free culture. In newborn Atg-/- mice, we observed uniform dilation of the pelvis accompanied by a coarse medulla, which was not noted in Atg+/- or Atg+/+ mice. Hydronephrosis in Atg-/- mice continued, and renal papillae underwent atrophy for the 4 weeks after birth. Another characteristic aspect of the morphology of Atg-/- mice was the thickening of vascular walls as little as 2 weeks after birth. Immunohistochemistry revealed recruitment of renin in hyperplastic vascular smooth muscle cells (VSMC) in Atg-/- mice after 2 weeks. Electron microscopy confirmed that the majority of hyperplastic VSMC contained various sized renin granules with abundant endoplasmic reticulum. In situ hybridization demonstrated that expression of renin mRNA became prominent in parallel with hyperplasia of VSMC, as well as recruitment of renin protein. Furthermore, at 4 weeks, Atg-/- mice expressed alpha-smooth muscle actin in the mesangium, whereas none was ever found in that of Atg+/- mice and Atg+/+ mice. In conclusion, the renin-angiotensin system seems not be essential for nephrogenesis in vivo. Furthermore, hyperplasia of VSMC and expression of the smooth-muscle phenotype in the mesangium are inducible even in the absence of angiotensin II, with hypotension, in vivo.

Examination of lesions in the urinary bladder and kidney of dogs induced by nefiracetam, a new nootropic agent

Toxic lesions induced by nefiracetam, a nootropic drug, in the urinary bladder and kidney were examined by repeated oral administration of 300 mg/kg/day for 1, 2, 3, 4, or 11 wk to male and female beagle dogs. Each dog was sacrificed after each treatment period, and urinalysis and serum biochemistry were performed for surviving dogs at several time points. One male and 2 females died during week 10 or 11. Degeneration and desquamation of epithelial cells and edema and hemorrhage in the lamina propria were observed in the urinary bladder after 1 wk of treatment. These changes became severe as time progressed and were reflected in the clinical abnormalities of hematuria and increased protein excretion in urine. However, epithelial regeneration and hyperplasia were seen thereafter, and almost no change was seen in the urinary bladder after treatment for 11 wk. Instead of recovery as in the urinary bladder, the kidney showed epithelial degeneration and hyperplasia in the papilla and collecting duct and interstitial congestion and hemorrhage after treatment for 11 wk. Extensive hemorrhage and papillary necrosis were seen in animals that died during week 10 or 11 of dosing. These kidney changes were associated with increased urinary volume and decreased osmotic pressure. The lesions are thought to have a common etiopathogenesis and to be initiated by the epithelial damage with a time lag between expression of injury in the urinary bladder and the kidney.