Renal collecting duct carcinoma complicated with clear cell carcinoma of kidney: one case report / 中华泌尿外科杂志

Renal collecting duct carcinoma(CDC) is rare in clinic, complicated with clear cell renal cell carcinoma(ccRCC) of one kidney is extremely rare. We reported a case CDC complicated with ccRCC of one kidney. The patient was admitted as left low back pain and gross hematuria, preoperative CT examination showed that one tumor was found in the upper middle pole and another tumor at lower pole of the left kidney, and multiple enlarged lymph nodes in the medial edge of the kidney. CT diagnosis was renal collecting duct carcinoma complicated with clear cell carcinoma of the left kidney, retroperitoneal lymphatic metastasis and underwent radical nephrectomy. Postoperative pathological diagnosis was CDC(upper middle pole) complicated with ccRCC(lower pole)of the left kidney. The patients were treated with sunitinib for 6 months and survived 13 months, and died of extensive metastasis.

Hereditary leiomyomatosis and renal cell carcinoma syndrome-associated renal cell carcinoma: Morphological appraisal with a comprehensive review of differential diagnoses

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is an autosomal dominant syndrome wherein affected individuals are at risk for the development of cutaneous leiomyomas, early-onset multiple uterine leiomyomas, and an aggressive subtype of renal cell cancer. HLRCC is caused by germline mutations in the fumarate hydratase (FH) gene, which inactivates the enzyme and alters the function of the tricarboxylic acid/Krebs cycle. This article reviews the hitherto described morphologic features of HLRCC-associated renal cell carcinoma (RCC) and outlines the differential diagnosis and ancillary use of immunohistochemistry and molecular diagnostics for these tumors. The morphologic spectrum of HLRCC-associated RCC is wide and histologic features, including tumor cells with prominent nucleoli, perinucleolar halos, and multiple architectural patterns within the same tumor, which are suggestive of this diagnosis. FH immunohistochemistry in conjunction with genetic counseling and germline FH testing are the important parameters for detection of this entity. These kidney tumors warrant prompt treatment as even smaller sized lesions can demonstrate aggressive behavior and systemic oncologic treatment in metastatic disease should, if possible, be part of a clinical trial. Screening procedures in HLRCC families should preferably be evaluated in large cohorts.

Renal Cell Carcinoma With Three Types Of Morphologies- A Rare Entity

Renal cell carcinomas(RCC) are the most common solid lesions of kidney with commonest subtype being clear cell type. Very few studies have reported synchronous presentation of three different morphological variants of RCC. We present a case of renal cell carcinoma in a 50 year old female presenting with renal mass. Microscopic examination showed presence of papillary, clear cell and collecting duct types of morphologies, which is a rare finding. Hence thorough sectioning and microscopic examination should be done to rule out possibility of simultaneous presence of different morphological varieties of RCC.

Collecting duct renal cell carcinoma: Diagnosis and treatment experiences and prognostic analysis / 第二军医大学学报

Objective: To summarize the clinical experiences for diagnosis and treatment of collecting duct renal cell carcinoma (CDRCC) and to analyze its prognosis. Methods: A total of 21 CDRCC patients selected from 6 950 patients with renal cell carcinoma admitted to Changhai Hospital, Changzheng Hospital and Eastern Hepatobiliary Surgery Hospital of Naval Military Medical University (Second Military Medical University) were enrolled in this retrospective study. CDRCC was confrmed by pathological examination. Clinical data, pathological data, imaging data, surgical conditions, postoperative adjuvant treatment and follow-up information of the 21 patients were analyzed. Results: The proportion of CDRCC patients was 0.3% (21/6 950). There were 18 males and 3 females, with an average age of (55 ±13) years. The main symptoms were hematuria and flank pain. Computed tomography showed that the size of the kidney involved was enlarged, the outline of the mass was not smooth, and the boundary of the mass was not clear. After enhancement, the mass was heterogeneously enhanced. The maximum diameter of tumor ranged from 2.4 cm to 8.5 cm, with an average of (5.6± 1.7) cm. Lymph node metastases were observed in 5 patients and distant metastasis in 6 patients. TNM clinical stage: 8 cases in stage I, 2 cases in stage II, 5 cases in stage III and 6 cases in stage IV. Twenty patients received surgical treatment, but one did not because of poor general condition. The pathological features of the tumors were grey-white or grey-yellow in section, infltrating growth, irregular glandular tubular and papillary tissues, some of which had hobnail appearance, interstitial fibrous tissue proliferation and inflammatory cell infiltration. Immunohistochemical staining showed that very low molecular cytokeratin (CAM5.2), tumor-associated epithelial membrane antigen (EMA), paired box gene 8 (PAX8), and cytokeratin 7 (CK7) were positive, while carbonic anhydrase IX (CAIX), proto-oncogene tyrosine-protein kinase kit (C-kit), GATA binding protein 3 (GATA3), neutral endopeptidase (CD10), transformation-related protein 63 (P63), and cytokeratin 20 (CK20) were negative. Sixteen patients were followed up for (33.6 ± 28.9) months on average (range, 4 to 87 months). The median survival time was 39.1 months. One-, two- and fve-year survival rate was 71.5%, 57.2%, and 44.5%, respectively. The average survival time of 12 dead patients was (32.2 ± 27.5) months. Conclusion: CDRCC is a rare subtype of renal cell carcinoma with short course, rapid progression, high degree of malignancy and poor prognosis. Pathological examination is the golden standard for the diagnosis and surgery is the main treatment at present. Chemotherapy and targeted therapy can be used as adjuvant therapy. Early diagnosis and treatment are the key to a favorable prognosis.

Collecting duct carcinoma kidney masquerading as hydatid cyst: A rare case report and review of literature

Cystic renal masses pose diagnostic challenge especially when they belong to Bosniak Type II and III. Septal and nodular enhancement on computed tomography (CT) is the strongest predictor of malignant process. A unilocular cyst with a calcified rim or a multilocular cystic lesion with heterogeneity on CT goes in favor of hydatid disease. We report a case in a 65-year-old female who presented with painless hematuria, was found to have a cystic mass in the right kidney. The mass turned out to be collecting duct carcinoma after histopathological examination though imaging studies were in favor of a hydatid cyst.

Notch signaling in the collecting duct regulates renal tubulointerstitial fibrosis induced by unilateral ureteral obstruction in mice

BACKGROUND/AIMS: Mind bomb-1 (Mib1) encodes an E3 ubiquitin ligase, which is required for the initiation of Notch signaling. Recently, it was demonstrated that the renal collecting duct plays an important role in renal fibrosis. Here, we investigated the role of Notch signaling in renal fibrosis using conditional knockout mice with the specific ablation of Mib1 in renal collecting duct principal cells. METHODS: Mib1-floxed mice (Mib1f/f ) were crossed with aquaporin 2 (AQP2)-Cre mice in order to generate principal cell-specific Mib1 knockout mice (Mib1f/f :AQP2-Cre+). Unilateral ureteral obstruction (UUO) was performed, and mice were sacrificed 7 days after UUO. RESULTS: After performing the UUO, renal tubulointerstitial fibrosis and the expression of transforming growth factor β were markedly enhanced in the obstructed kidneys of Mib1f/f mice compared with the sham-operated kidney of Mib1f/f mice. These changes were shown to be even more pronounced in the obstructed kidneys of Mib1f/f :AQP2-Cre+ mice than in those of the Mib1f/f mice . Furthermore, the number of TUNNEL-positive cells in renal collecting duct was higher in the obstructed kidneys of Mib1f/f :AQP2-Cre+ mice than in the kidneys of Mib1f/f mice. CONCLUSIONS: Notch signaling in the renal collecting duct plays an important role in the regulation of renal tubulointerstitial fibrosis and apoptosis after UUO.

Renal collecting duct carcinoma: report of three cases and literature review / 中华泌尿外科杂志

Objective To investigate the clinicopathological features,diagnosis,differential diagnosis and prognosis of renal collecting duct carcinoma (CDC).Methods The clinical data of 3 patients with renal collecting duct carcinoma,during the period from January 2015 to November 2017,were retrospectively analyzed.3 patients were male with age ranged from 42 to 73 years old,mean of 57.5 years.Two lesions were located in the right kidney and one in the left kidney.Clinical manifestations were hematuria,abdominal mass and waist and abdomen pain.No laboratorial abnormality was found.CT examination showed the tumor diameter ranged from 3.1 to 5.1 cm,mean 3.9 cm.The tumors located in the medullary and renal pelvis with low density or mixed density.Those tumors extended to the peripheral of the kidney,which the boundary was unclear.During enhancement CT,the uneven enhancement effect could be observed.Radical nepheroectomy was performed in all patients.Results Postoperative pathological examination showed surface of incision was gray.The texture of tumor was hard.The invasive growth pattern could be noticed.Under the microscope,the tumors had small ducts and papillary structures of tubules with interstitial fibrosis and some sarcomatous differentiation.Immunohistochemical staining showed strong positive expression of vimentin,CK-L,CKpan and P504S,and positive expression of PAX-2,CK7 and EMA in different degrees.RCC,KSP,CD10,CD117,MOC-31 and TFE3 were all negative.All 3 cases were followed up from 1 to 15 months with an average of 6 months.One case was treated with chemotherapy because of extensive metastases after surgery.Chemotherapy was performed by dissolving 1 500 mg of fluorouracil in 1 000 ml of 5％ normal saline and instillation.It was administered once every 10-12 hours and once a day for 5 days in one cycle.However,the outcome was poor.1 patient died of tumor metastasis and recurrence 7 months after surgery.1 patient had no tumor remaining after surgery.Conclusions CDC is a very rare malignant epithelial neoplasm in kidney.It has obvious clinical symptoms,strong invasive pattern and poor prognosis.Imaging and ultrasonography only play an auxiliary role in diagnosis.CDC's unique histopathology is the main basis of diagnosis and differential diagnosis.

Collecting Duct Carcinoma (Bellini Duct Carcinoma) Presented as a Renal Cyst

Renal cysts are frequently seen in the general population. Most small simple renal cysts are managed by conservative treatment. A renal cell carcinoma (RCC) presenting as a renal cyst is extremely uncommon, and collecting duct carcinoma is a rare type of RCC. This report describes a collecting duct carcinoma initially presnted as a renal cyst. The patient was a 52-year-old man who had been diagnosed with a renal cyst in the left lower pole 8 years earlier but was not regularly follow-up. He presented with left flank pain and gross hematuria. Computed tomography revealed a heterogeneous enhanced mass in the left lower pole and multiple para-aortic lymph nodes. He underwent radical nephrectomy and lymph nodes dissection which confirmed collecting duct carcinoma with sarcomatoid differentiation.

Synchronous Clear Cell Renal Cell Carcinoma And Tubulocystic Renal Cell Carcinoma

Tubulocystic renal cell carcinoma (TCRCC) is a recently described rare subtype of RCC. To best of our knowledge less than 70 cases have been reported till date. The concurrent papillary RCC (PRCC) and TCRCC has been documented in literature, but the co-occurrence of clear cell RCC (CCRCC) and TCRCC is very rare. We are describing a rare case of incidentally detected TCRCC occurring with CCRCC in a 45 years old male who presented with high grade fever with chills and rigors. Grossly, there were two distinct tumors in the total nephrectomy specimen. The larger tumor displayed the histopathological features of CCRCC and the smaller tumor revealed the features of TCRCC.treatment in the present case.

Resveratrol attenuates 4-hydroxy-2-hexenal-induced oxidative stress in mouse cortical collecting duct cells

Resveratrol (RSV) may provide numerous protective eff ects against chronic inflammatory diseases. Due to local hypoxia and hypertonicity, the renal medulla is subject to extreme oxidative stress, and aldehyde products formed during lipid peroxidation, such as 4-hydroxy-2-hexenal (HHE), might be responsible for tubular injury. This study aimed at investigating the eff ects of RSV on renal and its signaling mechanisms. While HHE treatment resulted in decreased expression of Sirt1, AQP2, and nuclear factor erythroid 2-related factor 2 (Nrf2), mouse cortical collecting duct cells (M1) cells treated with HHE exhibited increased activation of p38 MAPK, extracellular signal regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and increased expression of NOX4, p47(phox), Kelch ECH associating protein 1 (Keap1) and COX2. HHE treatment also induced NF-κB activation by promoting IκB-α degradation. Meanwhile, the observed increases in nuclear NF-κB, NOX4, p47(phox), and COX2 expression were attenuated by treatment with Bay 117082, N-acetyl-l-cysteine (NAC), or RSV. Our findings indicate that RSV inhibits the expression of inflammatory proteins and the production of reactive oxygen species in M1 cells by inhibiting NF-κB activation.

Role of Ammonia Transporters in the Kidney with Ureteral Obstruction / 대한내과학회지

Recent studies have identified a new family of ammonia transporters, Rh B glycoprotein (Rhbg) and Rh C glycoprotein (Rhcg). Rhbg and Rhcg are expressed in the collecting duct system of the kidney. Although it remains controversial whether Rhbg contributes to renal ammonia transport, Rhcg expression parallels ammonia excretion in a variety of experimental models. Kim et al. made an animal model of unilateral ureteral obstruction and demonstrated a decrease in urinary ammonia excretion. Immunohistochemistry with quantitative morphometric analysis revealed that total intensity of Rhcg expression significantly decreased in the obstructed kidney, but did not change in the non-obstructed kidney. These results suggest that decreased Rhcg is likely to cause for the impaired renal ammonia excretion in unilateral ureteral obstruction.

Renal collecting duct carcinoma: imaging spectrum with CT and MRI / 中华泌尿外科杂志

Objective To summarize the experience of using CT and MRI to diagnose the renal collecting duct carcinoma.Methods From February 2005 to January 2012,10 cases with renal collecting duct carcinoma,confirmed by pathology,were reviewed retrospectively.The data contained 6 men and 4 women,whose age ranged from 21 to 62 years (mean age 48 years).The flank pain was complained by 7 cases,waist discomfort was complained by 3 cases.In urine laboratory test,positive urine erythrocytes (++++) were found in 6 cases.In 10 cases,7 cases accepted CT examination and 3 cases accepted MRI examination.The growth pattern,lesion location,dynamic enhanced scan phase of the tumor and the way of spreading and metastasis were analyzed based on those CT and MRI images.Results The lesions were located in the left kidney in 6 cases,located in the right kidney in 4 cases.The size of tumors ranged from 4.4 cm×5.8 cm to 7.2 cm× 7.4 cm (mean size 5.7 cm× 6.4 cm).The mass,located in the center of renal parenchyma with irregular shape,showed infiltrative growth pattern.The shape of kidney was normal,whereas the border line between cortex and medulla was indistinct.The tumor involved the renal cortex and medulla in 4cases and involved the renal cortex,medulla,pelvis simultaneously in 6 cases.Among 7 patients who accepted the CT scanning,the solid mass was revealed in 6 cases.On CT plain scanning,the masses demonstrated slightly low or equal density within flaky or patchy low-density necrosis.Two cases showed small punctate calcification within the mass.One case was solid and cystic mass,which the cystic part of the mass showed irregular shape of the liquid-density.Among 3 patients accepted MRI scanning,all masses showed solid characters.The substantial part showed slightly hypointense on T1WI and low signal intensity on T2WI.The necrotic foci demonstrated low signal intensity on T1WI and high signal on T2WI.Dynamic enhanced scan revealed mild to moderate enhanced in the substantive part.The density of signal was lower than the renal cortex and slightly higher than the renal medulla in corticomedullary phase.It enhanced continuously in parenchymal phase,but still lower than the renal parenchyma.It enhanced continuously in the delayed phase,while the cystic or necrotic lesions were not observed the enhancement.Renal artery was surrounded by the mass in 2 cases.Tumor embolus was found in the renal vein in 2 cases,9 cases were noticed with renal hilum and paraortic hyperlymphonodus.The thoracic and lumbar spinal metastasis was found in 1 case and adrenal metastasis was found in another case.All patients underwent radical nephrectomy,that pathological diagnosis was renal collecting duct carcinoma.Conclusions The CT and MRI imaging characteristics of renal collecting duct carcinoma can be described as the mass located in the center of renal parenchyma with the infiltrative growth pattern.In MRI image,it demonstrates low signal intensity on T2WI.And a mild continuously enhanced can be observed on dynamic enhanced scanning.Moreover,the tumor often involves renal hilum,perirenal fat capsule,paraortic lymph node,and shows the tendency of distant metastasis.

Collecting Duct Carcinoma of the Kidney.

Collecting duct carcinoma (CDC) is a rare, highly aggressive malignant neoplasm that arises from the collecting duct epithelium of the kidney. It generally pursues a more aggressive course than conventional renal cell carcinoma. The average age is approximately 53 years. These are large tumors commonly located in medulla or central part of kidney with extension into perinephric fat and invasion into renal pelvis. Microscopically, they show combined tubulo-papillary, microcystic and solid growth pattern; cells are highly atypical with a basophilic or eosinophilic cytoplasm and polymorphic nuclei, often of the hobnail type. Stromal desmoplasia and dysplastic changes in the neighbouring medullary renal tubules are often associated. Their biologic behaviour is mostly aggressive with a high rate of local, lymphatic and haematogenous spread at the times of diagnosis and a poor long-term prognosis.

Collecting duct renal cell carcinoma with the syndrome of inappropriate antidiuresis: An autopsy case report.

A 57-year-old Japanese man visited our hospital with a moist cough. Chest radiographic imaging showed a left hilar shadow. Adenocarcinoma cells were found on cytologic screening of fresh sputum. Although multiple metastases including brain were detected, no tumor was observed in the kidneys. The patient underwent whole-brain irradiation and chemotherapy for advanced-stage lung cancer. One month before his death, carcinomatous meningitis was detected. Hyponatremia, hypo-osmolality, and hypertonic urine suggested the syndrome of inappropriate antidiuresis. Restricting water intake improved the hyponatremia; however, he developed fever and hematuria. Despite systemic administration of an antibacterial drug, he died. Primary tumor in the lung was absent, but adenocarcinoma of the right kidney was evident on autopsy. Lectin histochemical analysis of the carcinoma revealed its distal nephron origin, confirming collecting duct carcinoma. Severe carcinomatous meningitis, which is possibly caused the syndrome of inappropriate antidiuresis, was observed, with no cancer involvement of the pituitary gland and hypothalamus.

Clinicopathologic features of collecting duct carcinoma of the kidney-report of 5 case and review ;of literature / 中国癌症杂志

Background and purpose: Collecting duct carcinomas of the kidney are a rare malignant tumor accounting for<1%of renal malignancies. It is associated with aggressive nature and more than 50%of patients have metastatic disease at the time of initial diagnosis. The diagnosis of collecting duct carcinoma is often dififcult and to some extent is one of exclusion. This study aimed to study the clinicopathologic features of collecting duct carcinoma of the kidney. Methods:We retrieved the data of ifve cases of collecting duct carcinomas of the kidney from pathology ifles, and determined the expressions of CK19, CAM5.2, CK7, Vimentin, CD10, P63 and PaX-8 by pathohistological observation and immunohistochemical examination. Results: The most common symptoms were blood urine, bellyache and abdomen mass. The tumor originated from the medulla of the kidney central zone. Histologically, the tumors demonstrated irregular tubular or papillary architecture with the stroma of inflammatory cells and fibrous tissue proliferation. Immunohistochemically, the tumor cells were positive for CK19(5/5), CAM5.2(5/5), PaX-8(5/5), Vimentin(2/5), CK7(1/5), and negative for P63, CD10. Conclusion: The correct diagnosis in collecting duct carcinomas of the kidney is based on characteristic morphological features and immunophenotype labeling.

Effects of Hyperosmolality on Expression of Urea Transporter A2 and Aquaporin 2 in Mouse Medullary Collecting Duct Cells / 华中科技大学学报（医学）（英德文版）

In this study,the effects of hyperosmolality on the expression of urea transporter A2 (UTA2) and aquaporin 2 (AQP2) were investigated in transfected immortalized mouse medullary collecting duct (mIMCD3) cell line.AQP2-GFP-pCMV6 and UTA2-GFP-pCMV6 plasmids were stably transfected into mIMCD3 cells respectively.Transfected mIMCD3 and control cells were cultured in different hypertonic media,which were made by NaCl alone,urea alone,or an equiosmolar mixture of NaCl and urea.The mRNA and protein expression of AQP2 was elevated by the stimulation of NaCl alone,urea alone and NaCl plus urea in AQP2-mIMCD3 cells; whereas NaCl alone and NaCl plus urea rather than urea alone increased the mRNA and protein expression of UTA2 in UTA2-mIMCD3 cells,and all the expression presented an osmolality-dependent manner.Moreover,the mRNA and protein expression of UTA2 rather than AQP2 was found to be synergistically up-regulated by a combination of NaC1 and urea in mIMCD3 cells.It is concluded that NaC1 and urea synergistically induce the expression of UTA2 rather than AQP2 in mIMCD3 cells,and hyperosmolality probably mediates the expression of AQP2 and UTA2 through different mechanisms.

Clinical and pathological analysis of collecting duct carcinoma of the kidney / 中华泌尿外科杂志

Objective To analyze the clinical and pathological features of collecting duct carcinoma (CDC) of the kidney. Methods 11 patients with CDC were analyzed,among which 6 were males and 5 were females.Their age ranged from 22 to 67 years old with a mean age of 55.4 cases were found by routine health examination,4 cases were presented with gross hematuria and 3 cases had flank or abdomen pain.The CT scan showed an unclear boundary mass in kidney,with tumor sizes from 2.1 to 8.5 cm ( mean 5.6 cm).Only medullary involvement was present on CT in 3 cases,Medullary and cortical involvement in 5 cases,Medullary and pelvic involvement in 2 cases,and all involvement in 1 case.Infiltrative lesion has expanded kidney but maintains reniform contour.Contrast-enhanced CT scan showed lesion mild to moderate enhancement compared with surrounding parenchyma. Results Radical nephrectomy was performed in 8 cases and palliative nephrectomy in 3 cases.All patients were finally diagnosed by pathology.Grossly,the tumor is often appears gray or white.In HE staining,tumor showed prominent tubular or tubulaopapillary structures with desmoplasia and inflammatory reaction.Occasionally,some tumor cells take on a hobnail appearance.Immunohistochemical examination showed UEA-1 positive in all cases,EMA positive in 9 cases,PNA positive in 8 cases,and HMW-CK positive in 7 cases.Only 2 patients showed positive CD10.7 patients died within 6 to 47 months (mean 12.5 months),2 survived with tumor free for 9 months and 8 years respectively,one lost of follow-up,and one patient with distant metastasis is receiving postoperative chemotherapy. Conclusions Collecting duct carcinoma of the kidney is a rare histological type of renal cell carcinoma,whose final diagnosis depends on histopathological examination.Rapid progression,highly malignant,poor prognosis are the characteristics of this disease.

Enhanced Expression of Carbonic anhydrase II in Hypokalemic Rat Kidney / 체질인류학회지

A number of acid-base or electrolyte disorders are associated with decreased or increased HCO3- reabsorption in the renal tubules. The present study was to examine the alterations of expression and distribution of Carbonic anhydrase II in the kidneys of normal and potassium-depleted rats using Western blot analysis and immuno-histochemistry. Western blot analysis demonstrated that CA II protein, ~30 kDa at molecular mass, was abundantly expressed in normal group. All potassium-depleted groups showed slightly increased CA II protein compared to normal group. In control group, immunoreactivity of CA II protein was detected in the entire collecting duct. Signal intensity was prominent in the intercalated cells and weak in the principal cells of the cortical collecting ducts. In potassium-depleted groups, the pattern of cellular labeling of CA II protein was identical to that of normal group, but the signal intensity was decreased in cortical collecting duct, markedly increased in the inner stripe of outer medullary and inner medullary collecting ducts, and unchanged in the outer stripe of outer medullary collecting duct. These results suggest that chronic hypokalemia impact the expression pattern of CA II protein depending the portion of the collecting duct.

Renal Expression of Ammonia Transporters in Rats with Amiloride-Induced Renal Tubular Acidosis / 대한내과학회지

BACKGROUND/AIMS: Renal tubular acidosis (RTA) decreases the net acid excretion, predominantly due to a decrease in urinary ammonia excretion. This study examined whether this decrement is associated with changes in the renal expression of the ammonia transporter family members, Rh B glycoprotein (Rhbg) and Rh C glycoprotein (Rhcg), in rats with amiloride-induced RTA. METHODS: Male Sprague-Dawley rats were treated intraperitoneally with amiloride (3 mg/kg/day) for 6 days. Rhbg and Rhcg expression was evaluated by immunoblotting and immunohistochemistry. Cell height, total cellular expression, expression in the apical 25% of the cell, and apical expression as a percentage of total expression were quantified using immunohistochemistry with quantitative morphometric analysis. RESULTS: After amiloride treatment for 6 days, the serum bicarbonate level was decreased, and serum potassium was increased. The total urinary ammonia excretion and potassium excretion were decreased. The total Rhbg and Rhcg protein expression levels were not changed in the cortex or outer medulla of the kidney. Light microscopy and immunohistochemistry with quantitative morphometric analysis demonstrated that total Rhcg expression was decreased in the cortical collecting duct (CCD) and outer medullary collecting duct (OMCD) in amiloride-induced RTA, whereas Rhbg immunoreactivity was unchanged. CONCLUSIONS: Rats with amiloride-induced RTA have decreased urinary ammonia excretion associated with decreased Rhcg expression in the CCD and OMCD, suggesting that the ammonia transporter Rhcg plays an important role in the pathogenesis of amiloride-induced RTA.

Computer-assisted 3D Reconstruction of Mouse Connecting Tubule / 中国医科大学学报

Objective To study the spatial arrangement of mouse connecting tubules（CNT）and their transition to collecting duct system.Methods The renal tissues of three C57/BL/6J mice were fixed by perfusion and embedded in Epon 812.Totally 2 000 consecutive sections with the thickness of 2.5 μm were obtained from the renal surface to the papilla.The serial images under microscope were digitalized and aligned.Thirty eight CNT were traced with a series of computer programs.Results The CNT from long loop nephron ascended towards renal capsule and merged with 5 to 6 CNT from short loop nephrons to form the so-called arcade,while the latter or some of the CNT from the superficial cortex directly drained into the collecting duct in the superficial cortex.The lengths of CNT and the arcade ranged from 150 μm to 500 μm and 600 μm to 900 μm respectively.Conclusion The arcade or CNT drains into collecting duct only at superficial cortical level,which suggests that the reabsorption of the glomerular ultra-filtration in collecting ducts keeps unaffected when collecting duct runs through middle to deeper cortex.