Renal collecting (Bellini) duct carcinoma displays similar characteristics to upper tract urothelial cell carcinoma

OBJECTIVES

To describe 3 cases of tumors located in the kidney that may relate collecting (Bellini) duct carcinoma (CDC) to urothelial cell carcinoma (UC). We hypothesized that these distinct tumor types may share a common origin. CDC is a subtype of renal cell carcinoma associated with a highly aggressive course, poor prognosis, and limited response to immunotherapy, behaving similarly to UC.

METHODS

We present 2 cases of CDC and 1 case of UC of the renal papilla. We compared the clinical presentation and survival rate, together with the radiologic, histologic, and immunostaining (including p53) findings, with strong emphasis on the similarities.

RESULTS

One patient with CDC had a previous history of grade 3, Stage Ta bladder UC. The urothelial carcinoma from the kidney papilla (case 3) presented carcinoma in situ of the adjacent urothelium and displayed mixed characteristics with CDC, namely location, positive staining for Ulex europaeus and pyelonephritic changes. p53 staining showed marked positivity in the tumor of patient 2. Disease progression was rapid, with a median survival of 5.6 months (range 5 to 7).

CONCLUSIONS

The results of this study suggest that the broad category of renal cell carcinoma includes a spectrum of lesions. In this range of diseases, CDC might be distinct from conventional renal cell carcinoma but share biologic features with UC, with the consequent implications for management. This association between CDC and UC may reflect the common embryologic origin of collecting duct and urothelial cells, since they derive from progressive branching of the mesonephric (wolffian) duct. Furthermore, the differential cytogenetic expression profiles suggest that the molecular events underlying the development of distal nephron and proximal tubule renal cancers are distinct.

Renal papillae metastasis of sigmoid colon adenocarcinoma

Colonic carcinoma metastatic to the kidney is very rare. The usual anatomical localization for secondary renal neoplasms is the renal cortex. We report a case of sigmoid colon carcinoma with unilateral kidney metastasis localized only in the renal papillae without obvious metastatic disease.

Response of renal medullary cells to osmotic stress

In antidiuresis renal medullary cells are exposed to high NaCl and urea concentrations. Long-term adaptation of renal medullary cells to high extracellular NaCl concentrations is accomplished by intracellular accumulation of organic osmolytes. The underlying mechanisms include enhanced uptake from the extracellular space (betaine, myo-inositol and amino acids), increased intracellular production [sorbitol and glycerophosphorylcholine (GPC)] and reduced intracellular degradation (GPC). Apart from osmotically balancing the high extracellular NaCl concentration, betaine and GPC also contribute to protecting medullary cells against the adverse effects of high urea concentrations. A similar function has been demonstrated for HSP70, which is expressed abundantly in the inner medulla. The functional significance of osmolyte accumulation and HSP70 expression for medullary cells is highlighted by observations showing that inappropriately low rates of intracellular osmolyte accumulation or HSP70 expression are associated with an increased incidence of apoptotic cell death.

L-Arginine Does Not Affect Renal Morphology and Cell Survival in Ischemic Acute Renal Failure in Rats

BACKGROUND

L-Arginine (L-Arg), a substrate of nitric oxide synthases, improves renal function in ischemic acute renal failure (iARF). We evaluated whether L-Arg improves renal morphology and cell survival in the course of iARF.

METHODS AND RESULTS

iARF was induced in rats by bilateral clamping of renal arteries for 45 min. L-Arg was applied intraperitoneally during clamping, and orally during 14 days of follow-up. Morphology and cell survival of renal cortical and medullar tissue was analyzed on days 1, 3, 7, and 14 of follow-up, using toluidine blue staining and immunohistochemistry of perfusion-fixated tissue, and Western blot analysis of tissue homogenate. Renal tubular injury showed typical features of necrosis and was most severe on days 1 and 3 after clamping, predominantly in S3 segments, with almost complete recovery by day 14. Enhanced medullar monocyte infiltration, determined by ED-1 expression as well as by immunohistochemistry, and enhanced expression of proliferating cell nuclear antigen (PCNA), indicative of proliferation and regeneration, accompanied these morphological changes. Compared to controls, L-Arg had no impact on renal morphology, ED-1, and PCNA expression. Furthermore, expression of markers of apoptosis Bcl-2, Bax, and cleaved caspase-3 was only slightly increased in iARF rats, compared to sham-operated animals, and was also not influenced by L-Arg.

CONCLUSION

Despite its repeatedly reported positive impact on renal function as also shown in our model, L-Arg does not alter cell death and proliferation in the course of iARF in our model. Thus, different mechanisms have to be considered, in particular improved intrarenal hemodynamics.

A transcriptional profile of aging in the human kidney

In this study, we found 985 genes that change expression in the cortex and the medulla of the kidney with age. Some of the genes whose transcripts increase in abundance with age are known to be specifically expressed in immune cells, suggesting that immune surveillance or inflammation increases with age. The age-regulated genes show a similar aging profile in the cortex and the medulla, suggesting a common underlying mechanism for aging. Expression profiles of these age-regulated genes mark not only age, but also the relative health and physiology of the kidney in older individuals. Finally, the set of aging-regulated kidney genes suggests specific mechanisms and pathways that may play a role in kidney degeneration with age.

A study of human aging in the kidney reveals similar changes in the transcriptional profile in cortex and medulla, suggesting that a common underlying aging process is taking place

A case of renal angioleiomyoma with rapid growing: CT findings with histopathological correlation

We present a rare case of renal angioleiomyoma with rapid growing during one-year and seven-months' follow-up. The CT findings correlated well with the histopathological findings. The patient was a 62-year-old man with right renal mass that was incidentally found on CT. The first CT showed a solitary mass lesion that was 2.0 cm in diameter with a well-defined margin at the right renal medulla. It was gradually enhanced on contrast-enhanced CT. Follow-up CT was performed after one year and seven months, and the mass had grown to 3.8 cm in diameter and showed heterogeneous density on unenhanced CT. The mass had an early enhanced area in the corticomedullary phase, and this enhancement lasted into the nephrographic phase. Another area was gradually enhanced heterogeneously. Right radical nephrectomy was performed, and the histopathological diagnosis was renal angioleiomyoma. The early enhanced area of the mass corresponded to large vessels filled with blood, and the other area was mainly composed of bundles of smooth muscle, fibrous tissue, and minute blood vessels. It is important to know that the CT findings of real angioleiomyoma may show hypervascularity but are atypical for renal cell carcinoma (RCC), and a tendency for growth may be present.

Cytokine gene expression profiles in kidney medulla and cortex of obese hypertensive dogs

BACKGROUND

The molecular mechanisms linking abnormal kidney function and obesity hypertension are poorly understood. This study compared gene expression profiles in the kidney medulla and cortex of obese and lean dogs.

METHODS

Lean dogs (N= 4) were fed a standard kennel ration and obese dogs (N= 4) were fed the standard diet plus 0.5 to 0.9 kg of cooked beef fat per day for 10 weeks. The dogs were instrumented for continuous monitoring of mean arterial pressure (MAP), heart rate, glomerular filtration rate (GFR), and effective renal plasma flow (RPF). The relative mRNA levels of 375 genes in renal cortex and medulla were determined simultaneously using cDNA membrane arrays (R&D Systems).

RESULTS

The high fat diet increased body weight by 57% and MAP increased by 24 mm Hg (112 +/- 1 mm Hg vs. 88 +/- 3 mm Hg) in obese compared to lean dogs. In obese dogs, expression of 11 and 13 genes changed significantly (N= 4; P < 0.05) in the renal medulla and the cortex, respectively, relative to the lean dogs. Differences in renal gene expression profiles between lean and obese dogs were closely related to functional pathways, including those associated with sympathetic activation, inflammatory response, matrix formation, angiogenesis, endothelial dysfunction, attenuated actions of leptin, and attenuated cell survival.

CONCLUSION

A high fat diet in dogs is associated with marked changes in renal gene expression profiles that provide potential molecular links to pathways associated with altered renal function and structure in obesity hypertension.

Parapelvic kidney cysts: A distinguishing feature with high prevalence in Fabry disease

BACKGROUND

Fabry disease is an X-linked generalized progressive debilitating lysosomal storage disorder. The disease usually manifests in childhood, but the diagnosis is often made following the occurrence of late-stage complications such as progressive kidney failure. In order to identify key novel renal diagnostic imaging features of Fabry disease, we conducted a cross sectional case-control study of kidney involvement in patients with Fabry disease.

METHODS

Twenty-four patients (mean age 36.1 +/- 8.1 years, median 37 years, range 20 to 48 years) with chronic neuropathic pain who were enrolled in an enzyme replacement trial underwent prospective renal imaging evaluation with magnetic resonance imaging (MRI) and computed tomography (CT) at the National Institutes of Health, Bethesda, Maryland. We concurrently enrolled 19 age-matched healthy controls (mean age 34.6 +/- 12.0 years, median 33 years, range 18 to 61 years). The presence and localization of kidney cysts as well as the ratio of the signal intensity between medulla and cortex were determined.

RESULTS

Fifty percent of the Fabry disease patients had renal sinus cysts, compared to one individual (7%) in the control group. The ratio of the signal intensity between medulla and cortex on T2-weighted scans in Fabry disease patients with sinus cysts was elevated compared with Fabry disease patients without cysts (P= 0.0083), and elevated in Fabry disease patients without cysts compared with normal controls without cysts (P= 0.0173).

CONCLUSION

The finding of multiple renal sinus cysts in the workup of a patient with kidney disease patient should strongly suggest the consideration of Fabry disease in the differential diagnosis. The cause of such cysts in Fabry disease remains to be elaborated.

Urine calcium and volume predict coverage of renal papilla by Randall's plaque

BACKGROUND

Renal papillary plaques are common in calcium stone formers. We hypothesized that plaque should increase directly with urine calcium excretion, and inversely with urine volume. To test this, we measured papillary plaque areas in both idiopathic calcium oxalate stone formers and nonstone formers and examined 24-hour urine data to identify significant correlations.

METHODS

Fourteen stone formers and four nonstone forming controls underwent papillary mapping with flexible nephroscopy. For each papillum, representative still images and moving pictures expert group (MPEG) movies were used to identify plaque extent and papillary borders. The mean fractional plaque coverage for each polar region (upper, inter, lower) and per papillum was calculated. The relationship of the plaque coverage data to urine measurements was assessed with general multivariate linear modeling.

RESULTS

Mean polar fractional plaque coverage was higher in the calcium oxalate stone formers (7.4% vs. 0.5%, P= 0.012) as was mean fractional plaque per papillum (7.6% vs. 0.6%, P= 0.011). When correlating mean polar plaque coverage to urine data, urine volume and calcium excretion were the only measurements with independent relationships to plaque (P= 0.002, adjusted multiple R2= 0.521), with higher calcium and lower volume increasing coverage. The same relationships hold for mean plaque per papillum, except that urine pH also becomes an independent factor (P= 0.001, adjusted multiple R2= 0.606).

CONCLUSION

Utilizing advanced digital video and endoscopic equipment, we have achieved the most accurate estimation of papillary plaque coverage to date. Our findings support the idea that urine volume and calcium are the main correlates of plaque coverage.

Morphological changes induced in the pig kidney by extracorporeal shock wave lithotripsy: nephron injury

While shock wave lithotripsy (SWL) is known to cause significant damage to the kidney, little is known about the initial injury to cells along the nephron. In this study, one kidney in each of six juvenile pigs (6-7 weeks old) was treated with 1,000 shock waves (at 24 kV) directed at a lower pole calyx with an unmodified HM-3 lithotripter. Three pigs were utilized as sham-controls. Kidneys were fixed by vascular perfusion immediately after SWL or sham-SWL. Three of the treated kidneys were used to quantitate lesion size. Cortical and medullary samples for light (LM) and transmission electron microscopy (TEM) were taken from the focal zone for the shock waves (F2), the contralateral kidney, and the kidneys of sham-SWL pigs. Because preservation of the tissue occurred within minutes of SWL, the initial injury caused by the shock waves could be separated from secondary changes. No tissue damage was observed in contralateral sham-SWL kidneys, but treated kidneys showed signs of injury, with a lesion of 0.2% +/- 0.1% of renal volume. Intraparenchymal hemorrhage and injury to tubules was found at F2 in both the cortex and medulla of SWL-treated kidneys. Tubular injury was always associated with intraparenchymal bleeding, and the range of tissue injury included total destruction of tubules, focal cellular fragmentation, necrosis, cell vacuolization, and membrane blebbing. The initial injury caused by SWL was cellular fragmentation and necrosis. Cellular vacuolization, membrane blebbing, and disorganization of apical brush borders appear to be secondary changes related to hypoxia.

Cellular and molecular studies on cisplatin-induced apoptotic cell death in rat kidney

Using morphological and molecular approaches, we characterized cisplatin-induced cell necrosis and apoptosis in rat kidney. Male Sprague-Dawley rats ( n=5 per group) received a single intraperitoneal injection of either cisplatin (5 mg/kg) or saline, and were killed on day 5. Functionally, cisplatin-treated rats developed polyuric acute renal failure. Morphologically, kidneys of cisplatin-treated rats showed overt tubular necrosis associated with apoptosis in the corticomedullary junction. Cell necrosis was segment-specific and was distributed in radial fashion at the corticomedullary junction. The apoptosis was limited to discrete cells in apparently intact tubules in the vicinity of the necrosed tubules. The apoptotic changes were confirmed by TUNEL (TdT-mediated deoxyuridine triphosphate nick-end labeling) and staining for cleaved caspase-3. Analysis of outer medullary tissue for apoptosis-related molecules by RNase protection assay revealed a significant increase in the expression of pro-apoptotic mRNAs (caspases 1, 2, and 8, and Bax) in cisplatin-treated rats. On the other hand, the expression of mRNA for the anti-apoptotic Bcl-2 did not change, resulting in a decrease in relative ratio of Bcl-2/Bax, and thus favoring apoptosis. The above changes were paralleled by a marked increase in caspase-3 precursor, the executioner protease. Furthermore, these pro-apoptotic molecular changes were associated with a 3-fold increase in the activity of JNK1 in the outer medulla, but not in the cortex, of cisplatin-treated rat kidneys, localizing to the site of maximal apoptosis. Upregulation of JNK1 activity in the outer medulla was not accompanied by changes in the activities of ERK or p38 kinase. In conclusion, these data suggest that cisplatin-induced apoptotic cell death in native kidney may be mediated by cooperative activation of the JNK1 pathway and Bax in the outer medulla.

Normalization of renal aquaporin-2 water channel expression by fosinopril, valsartan, and combination therapy in congestive heart failure: a new mechanism of action

This study investigated the effect of fosinopril (Fos), valsartan (Val), and combination of both drugs (Fos + Val) on the cardiac and renal expression of aquaporin-1 (AQP1) and aquaporin-2 (AQP2) in congestive heart failure (CHF). A rat model of CHF was created by ligating the left anterior descending coronary artery to induce acute myocardial infarction (AMI). Rats were treated by Fos, Val, or Fos + Val for 4 weeks. In renal medulla and cortex, AMI was associated with 2.2- and 1.8-fold increase in AQP2 mRNA expression when compared with Sham-operated rats (medulla: 23.6 +/- 2.8 vs. 52.3 +/- 8.7%; P<0.001; cortex: 19.4 +/- 3.9 vs. 35.5 +/- 7.1%; P<0.05). All the treatment regimens were able to normalize AQP2 transcription in the renal medulla (Fos, 19.9 +/- 4.9%; Val, 22.8 +/- 4.9%; Fos + Val, 20.1 +/- 5.1%; P=NS vs. Sham) and in the cortex (Fos, 21.2 +/- 6.7%; Val, 20.4 +/- 6.0%; Fos + Val, 18.9 +/- 7.5%; P=NS vs. Sham). Similarly, the AQP2 protein expression increased by 2.1-fold after CHF (P<0.05), and was normalized by the treatment regimens (Sham, 0.57 +/- 0.19%; CHF, 1.22 +/- 0.45%; Fos, 0.39 +/- 0.36%; Val, 0.46 +/- 0.34%; Fos + Val, 0.36 +/- 0.15%; all P<0.05 vs. CHF). These treatment regimens also prevented the increase in body weight as found in untreated CHF rats (analysis of variance P<0.05). The renal and cardiac AQP1 gene and protein expressions were unaltered in CHF or by medical therapy. There was no observed cardiac AQP2 expression in all the study groups. Treatment with Fos, Val, or combination therapy was effective in preventing the upregulation of renal AQP2 gene and protein expressions in CHF rats caused by AMI.

Endoscopic renal papillary biopsies: a tissue retrieval technique for histological studies in patients with nephrolithiasis

PURPOSE

The mechanisms behind calcium nephrolithiasis remain unclear. Previous research has relied on animal models or cell lines, yielding limited insight into the pathophysiology of human calcium stone disease. To determine changes occurring in the human kidney during active stone disease we used an endoscopic renal papillary biopsy protocol in calcium stone formers undergoing percutaneous nephrolithotomy.

MATERIALS AND METHODS

Following stone burden clearance via percutaneous nephrolithotomy 15 idiopathic calcium oxalate and 4 ileal bypass stone formers underwent flexible and rigid nephroscopy. Biopsies from select papillae in the peripheral and interpolar regions were obtained with 5Fr flexible cup biopsy forceps. A papilla adjacent to the accessed calix was biopsied with 10Fr cup biopsy forceps. Cortical biopsies along the access tract were also obtained with the 10Fr forceps.

RESULTS

All patients had successful biopsy completion. No complications were attributable to the biopsy process and no blood transfusions were required. Of the 19 patients 12 were contacted for followup at a mean of 21.7 +/- 9.0 months with none experiencing adverse sequelae such as bleeding or significant pain. A total of 14 patients had followup serum creatinine available showing that the difference in mean preoperative and postoperative values was not clinically significant (1.00 +/- 0.27 and 1.11 +/- 0.27 mg/dl, respectively). The quality of biopsied tissue permitted accurate immunohistochemical staining of crystal deposits and mineral analysis.

CONCLUSIONS

Endoscopic papillary biopsies were performed safely in a small patient population. Tissue obtained using this protocol can be used for detailed histological and analytical studies, which may lead to significant advances in our understanding of stone formation mechanisms.

Multiphasic Helical CT Diagnosis of Early Medullary and Papillary Necrosis

PURPOSE

The feasibility of identifying early manifestations of renal papillary necrosis (RPN) and medullary necrosis (RMN) on multiphasic helical CT, leading to prompt treatment for the causative conditions, and its impact on reducing the incidence of late-stage RML and RPN, was investigated.

PATIENTS AND METHODS

Sixty-eight patients (35 male, 33 female) aged 19 to 88 years were examined by multiphasic helical CT for complaints of microscopic hematuria (N=49), macroscopic hematuria (N=2), bacteriuria (N=45), pyuria (N=10), fever (N=15), and flank pain (N=27). Preenhancement, arterial corticomedullary, parenchymal, and excretory phase scans generated 1.25 to 7-mm-thick slices. Follow-up CTs were performed at 1 month (N=62) and 3 months (N=58).

RESULTS

While the attenuation coefficients of areas suspect for RMN and RPN were similar on preenhancement CT, they differed substantially on the arterial corticomedullary phase (lesions 55 HU mean; normal medulla 120 HU mean) and parenchymal phase (lesions 58 HU mean, normal medulla 210 HU mean). Investigation for predisposing conditions identified diabetes in 18 patients, upper urinary-tract infections in 48, sickle-cell disease or trait in 17, urinary obstruction in 7, and cirrhosis of the liver in 1. On follow-up examinations, enhancement had normalized in 26 compromised areas of 14 patients at 1 month, and 47 areas (23 patients) at 3 months, remained stationary in 28 patients at 1 month and 9 at 3 months, and progressed in 20 at 1 and 26 at 3 months (P<0.001; Fisher's exact test). Patients (N=35) treated for underlying conditions causing ischemia showed reperfusion in 12 cases at 1 month and 20 at 3 months, while of the untreated patients (N=10), none showed reperfusion, and all lesions increased in size.

CONCLUSIONS

Multiphasic helical CT is recommended for identification of RMN and RPN at a stage when effective treatment of underlying causative conditions can arrest or reverse the process of devascularization and prevent loss of medullary tissue.

Chronic COX-2 inhibition reduces medullary HSP70 expression and induces papillary apoptosis in dehydrated rats11.See Editorial by Aufricht, p. 739

BACKGROUND

Papillary cells adapt to their hyperosmotic environment by accumulating organic osmolytes and by enhanced synthesis of heat shock protein 70 (HSP70), which protect against high-solute concentrations. Because cyclooxygenase-2 (COX-2) is expressed abundantly in the renal papilla and is induced by dehydration, and because HSP70 expression is stimulated by specific prostaglandins, COX-2 inhibition may interfere with cellular osmoadaptation.

METHODS

In vivo, rats received rofecoxib before water deprivation. Medullary expression of several tonicity-responsive genes was analyzed and apoptosis was monitored by transferase-mediated dUTP nick-end labeled (TUNEL) staining and determination of papillary caspase-3 activity. In vitro, inner medullary collecting duct 3 (IMCD3) cells were exposed to hypertonic medium containing a COX-2-specific inhibitor. Thereafter, expression of tonicity-responsive genes was analyzed and resistance to high-solute concentrations was examined. Further, the effect of Delta 12-PGJ2, a urinary prostaglandin, and of HSP70 overexpression on resistance against high urea concentration, was evaluated.

RESULTS

Rofecoxib treatment significantly increased urine osmolality due to higher urea concentrations, but reduced papillary HSP70 abundance by 50%. TUNEL staining showed numerous apoptotic cells in the papilla, associated with increased caspase-3 activity. These in vivo results were confirmed by experiments on cultured IMCD3 cells, in which COX-2 inhibition impaired the tonicity-induced up-regulation of HSP70 expression and rendered the cells susceptible to high urea concentrations. Furthermore, Delta 12-PGJ2 increased both HSP70 expression and resistance against high urea, which was causally linked to higher HSP70 levels.

CONCLUSION

These observations support the view that chronic COX-2 inhibition reduces medullary HSP70 expression, thus rendering papillary cells susceptible to damage by high urea concentrations, especially when accompanied by dehydration.

In vitro and in vivo ablation of porcine renal tissues using high-intensity focused ultrasound

The aim of this paper is to present issues regarding the thermal ablation of porcine renal tissues in vitro and in vivo using high-intensity focused ultrasound (HIFU). Production of lesions in the cortex in vitro is consistent, whereas lesions in the medulla are created whenever there are no air spaces in the medulla. Typically, the lesion length at 2000 W/cm2 and 5-s pulse duration is around 20 mm and the corresponding width around 3 mm. Lesioning of a large volume was achieved by moving the transducer in a grid formation. Lesioning through a fat layer is possible provided that there are no air spaces between the fat and kidney interface. It was found that, above 3200 W/cm2 with 5-s pulse duration at 4 MHz, cavitation activity occurred in most of the lesions created.

Mechanism of matrix accumulation and glomerulosclerosis in spontaneously hypertensive rats

BACKGROUND

Renal interstitial fibrosis and thickening of the glomerular basement membrane are associated with hypertension. However, the mechanism of matrix accumulation is unclear. Spontaneously hypertensive rats (SHR) develop hypertension at between 2 and 6 weeks of age.

METHODS

To test the hypothesis that increased matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) contribute to the pathomechanisms of hypertensive nephropathy, the cortex and medulla of male SHR at 2 and 6 weeks were analyzed for MMP-2, MMP-7, and MMP-9 by gelatin and elastin gel zymography. The levels of TIMP-4 were measured by western blot analysis. The bands in blots were scanned and normalized with actin. To localize MMP-2 and TIMP-4 in situ, immuno-labeling was performed. To determine proteinuresis, urinary protein was measured by Bio-Rad dye binding assay. The mean arterial pressure (mmHg) was measured in Inactin-anesthetized rats by a PE-50 catheter in the femoral artery. Age-sex matched normotensive Wistar rats (NWR) were used as controls and grouped: (1). SHR, 2 weeks; (2). SHR, 6 weeks; (3). NWR, 2 weeks; and (4). NWR, 6 weeks (n = 6 in each group).

RESULTS

Levels of cortex MMP-2 and MMP-9 were increased in 6 week SHR as compared with NWR. In the medulla, MMP-9 and MMP-7 were increased, but there was no change in MMP-2. The levels of cortex TIMP-4 tended to increase but insignificantly. In contrast, there were significant increases in the levels of TIMP-4 in the medulla of 6 week SHR as compared with 2 week SHR or NWR. In addition, there were substantial elastinolytic activity in the cortex of 6 week SHR. The in situ labeling suggested no TIMP-4 in the glomeruli. There was substantial TIMP-4 in the epithelial layer of tubules. The levels of fibrotic collagen were significantly higher in both the glomeruli and tubular interstitium. Urinary protein excretion was increased significantly in 6 week SHR when compared with other groups. The mean arterial pressure was 1.6-fold higher in 6 week SHR than in controls.

CONCLUSION

These results suggest that increased MMP-2 and MMP-9 activity contributes to glomerular injury and hypertensive remodeling. The increased levels of TIMP-4 in the medulla may inhibit the collagenolytic activity of MMP but is unable to inhibit the elastinolytic activity. An important role of MMP-2, MMP-9, and TIMP-4 in hypertensive remodeling of the cortex and medulla in the SHR is demonstrated.

In situ activation pattern of Met docking site following renal injury and hypertrophy

BACKGROUND

Hepatocyte growth factor/scatter factor (HGF/SF) binds to its tyrosine kinase receptor, Met, thereby stimulating diverse cellular responses. The multifunctional docking site in the C-terminal domain mediates the signal of phosphorylated Met receptors to multiple transducers. The tyrosine at position 1356 of the Met docking site is crucial for cell motility and morphogenesis.

METHODS

We examined the in situ distribution patterns of the Tyr1356-phosphorylated form of Met with a novel monoclonal antibody following renal injury and renal hypertrophy in rats. Sections of the kidney following either sham operation, transient ischaemia of one kidney or unilateral nephrectomy were analysed using indirect immunofluorescence staining and confocal laser scanning microscopy analysis of total Met protein levels and Tyr1356-phosphorylated Met (Met and pMet, respectively).

RESULTS

At 6 h post-treatment, pMet increases in ischaemic kidneys compared with sham-operated kidneys, and these changes become substantial after 48 h in both medulla and cortex of ischaemic kidneys (P < 0.001). We also show significant up-regulation of Met predominantly in the medulla of ischaemic kidneys, 48 h following injury (P < 0.009). Inter-estingly, the stimulus for hypertrophy in the remnant kidney after uninephrectomy and the contra-lateral kidney during ischaemia is not accom-panied by significant up-regulation of Met or pMet staining compared with sham operation at both time points.

CONCLUSIONS

We demonstrate in this work, for the first time, in situ detection of tyrosine kinase growth factor receptor docking site activation during pathological processes in the kidney. Using this methodology, we show a significant increase in Met docking site activity in both renal medulla and cortex solely following stimulation by ischaemia and repair.

Renal papillary necrosis induced by naproxen

A 17-year-old healthy girl was admitted to our hospital with diffuse abdominal pain and decreased oral intake of about 11 days duration. About a week prior to admission, she had taken naproxen, 250 mg four times a day for 4 days. Physical examination was normal except for diffuse abdominal tenderness on deep palpation. Investigations revealed high serum BUN (42 mg/dl) and creatinine (4.0 mg/dl). Serum electrolytes and complement (C3, C4) levels and urinalysis were normal. Antinuclear-antibody and anti-dsDNA were negative. Kidney biopsy revealed renal papillary necrosis, acute tubular necrosis, and focal interstitial nephritis. A diagnosis of nonoliguric acute renal failure due to naproxen nephrotoxicity was made. She received intravenous hydration, and oral steroids, which was gradually discontinued in 3 months. A follow-up at 4 months revealed normal renal function with a serum creatinine of 1.1 mg/dl, BUN 7 mg/dl, and normal urinalysis. The report highlights a need for caution while using naproxen or any other nonsteroidal anti-inflammatory drugs, even for a short duration.