Null mutation of PCLN-1/Claudin-16 results in bovine chronic interstitial nephritis

Inherited chronic renal diseases are associated with failures in glomerular filtration and tubular resorption. Such failures invariably result from defects in selective filtration and absorption in surface renal epithelium. Recently, we described an autosomal recessive chronic interstitial nephritis with diffuse zonal fibrosis (CINF) in cattle. Bovine CINF, characterized by increased blood urea nitrogen, creatinine, and urinary proteins, leads to lethality before puberty, usually within the first 6 months or year of life. Here, we demonstrate that the first four exons of PCLN-1/Claudin-16 (CL-16), which encodes a member of the claudin family of tight junction proteins, were deleted in CINF-affected cattle. CL-16 was expressed preferentially in kidneys of normal cattle, but transcripts were totally absent in affected offspring. This observation suggests that the lack of CL-16 protein contributes to the dysfunction of paracellular renal transport systems.

Genetic mapping of a locus associated with bovine chronic interstitial nephritis to chromosome 1

Chronic interstitial nephritis with diffuse zonal fibrosis (CINF) occurs in Japanese Black cattle (Wagyu) as an autosomal recessive disorder leading to death prior to puberty, first six months or a year of life. We performed a genome-wide scan using microsatellite markers in a Wagyu pedigree segregating for CINF and mapped the CINF locus to bovine chromosome 1. CINF was closest to microsatellites BM9019 and INRA49 (Z score = 12.0; P < 3.4 x 10(-10)).

Fibrosing cholestatic hepatitis after living related-donor renal transplantation

A 43-year-old man underwent living related-donor renal transplantation because of chronic renal failure in 1991. During the transplant period, both donor and recipient were seronegative for hepatitis B surface antigen (HBsAg). The donor was seropositive for antibody to hepatitis B surface antigen (anti-HBs) due to hepatitis B virus (HBV) vaccination. After transplantation, FK506 and methylprednisolone had been administered to the patient as immunosuppressants. In 1993, HBsAg appeared in his serum. His alanine aminotransferase level elevated gradually during 1995 and then in 1996, general fatigue, ascites and jaundice developed. At this time his serum was positive for hepatitis B e antibody, contained more than 100000 Meq/mL HBV-DNA and 100% precore mutant. Despite subsequent intensive therapy, liver dysfunction progressed and this patient died of hepatic failure 2 months following admission. At autopsy, the liver exhibited cholestasis, fibrosis extending from the portal tracts, mild inflammation and hepatocytes with a ground-glass appearance. In addition, HBsAg and hepatitis B core antigens had accumulated in the hepatocytes. Consequently, the final diagnosis was fibrosing cholestatic hepatitis (FCH) due to precore mutant HBV infection contracted after renal transplantation. It is unclear when and where the recipient liver became HBV infected. Nevertheless, after renal transplantation, while receiving immunosuppressive drugs, HBV appeared to have the potential to cause hepatic failure and FCH may have been a fatal complication for the recipient.

Requiring higher doses of erythropoietin suggests pregnancy in hemodialysis patients

BACKGROUND/AIMS

Pregnancy in hemodialysis (HD) patients tends to be diagnosed late because of its infrequency and the lack of validity of urine pregnancy tests, and because these patients tend to have menstrual irregularities. The outcome is influenced by pregnancy-related anemia. We investigated the characteristics of pregnancy-related anemia and whether it is a useful diagnostic clue to pregnancy in HD patients.

METHODS

We retrospectively investigated six pregnancies of 5 HD patients (mean age 30 years), including 4 patients treated with recombinant human erythropoietin (rHuEpo) and a transfusion-dependent patient with two pregnancies in the pre-rHuEpo era.

RESULTS

The mean duration of HD was 6 years, the mean duration of the patients' marriages at the time of pregnancy was 6 years, and the mean gestational age at diagnosis was 11 weeks and 4 days. The progression of anemia (an 8% decrease in the hematocrit) was detected by 8 weeks of gestation in all patients. The prepregnancy hematocrit was stable in 5 pregnancies, facilitating the detection of changes, but during one of the pregnancies of the transfusion-dependent patient the hematocrit was low and was influenced by the transfusions. The amount of rHuEpo required to attain a target hematocrit of 30% increased gradually or rapidly until delivery.

CONCLUSIONS

The progression of anemia or hyporesponsiveness to rHuEpo was a useful early diagnostic clue to pregnancy in HD patients. However, the prepregnancy hematocrit should be stabilized with rHuEpo, so that decreases can be easily detected. The precise mechanisms of hyporesponsiveness to rHuEpo, which progressed during pregnancy and subsided after delivery, remain to be clarified.

Prognosis of Japanese membranous nephropathy patients with nephrotic syndrome

We retrospectively investigated the prognosis and efficacy of various treatments in 58 Japanese patients with primary membranous nephropathy (MN). Patients were treated with prednisolone (PSL) + immunosuppressive (IS) agents (N = 22). PSL alone (N = 23), IS agents alone (N = 5) and aspirin or dipyridamole (N = 8). Overall, 25 patients (43.1%) achieved complete remission (CR), 11 (18.9%) achieved partial remission (PR) and 22 (37.9%) were non-responders (NR). The 10-year survival rate was 90% and the 10-year CR rate was 61.8% as determined by Kaplan-Meier analysis. There was no significant difference in the CR among treatment groups. Of the 22 patients in the PSL + IS group, 3 progressed to end-stage renal disease and 2, who were more than 65 years old, died of pneumonia. The clinical and histological data at renal biopsy did not significantly differ among the treatment groups. In conclusion, the overall prognosis of MN was excellent. Treatment with PSL and/or IS agents did not appear to be superior to treatment with aspirin or dipyridamole.

Histological localization of advanced glycosylation end products in the progression of diabetic nephropathy

We studied the immunohistochemical localization of advanced glycosylation end products (AGEs) in the progression of diabetic nephropathy. Fourteen NIDDM patients with diabetic nephropathy were evaluated: 2 patients with normoalbuminuria, 4 with microalbuminuria (MA) and 8 with overt proteinuria (OP). Three patients with minor glomerular abnormalities were used as nondiabetic controls. Immunoreactivity to a monoclonal anti-AGE antibody (6D12) was recognized on the internal elastic membranes of arterial walls in every diabetic group. Hyaline lesions of arterioles of the MA and OP groups demonstrated strong reactions with 6D12. A portion of the nodular and exudative lesions in glomeruli of OP group patients also revealed immunoreactivity to 6D12. No immunoreactivity to 6D12 was observed in nondiabetic control specimens. We confirm that the accumulation of AGEs began in arterial walls of the early stage and presented in glomerular lesions of the late stage of the progression of diabetic nephropathy.

Toxicity of emestrin, a new macrocyclic dithiodioxopiperazine mycotoxin, to mitochondrial function

The effect of emestrin, a new macrocyclic epidithiodioxopiperazine mycotoxin from severalEmericella species, on mitochondrial reactions was studied using isolated rat liver mitochondria to gain insight into the molecular mechanism for itsin vivo toxicity to rat and mouse. Emestrin was found to inhibit ATP synthesis in mitochondria causing an uncoupling of oxidative phosphorylation and a depression of respiration in isolated mitochondria. In addition to these effects on mitochondrial respiration, emestrin elicited a dratsic structural alteration (swelling) of mitochondria as observed in thein vivo system. The mitochondrial swelling was significantly enhanced by the subsequent addition of calcium ion. Emestrin B, in which dithio group is replaced by trithio group, exerted an uncoupling effect on oxidative phosphorylation without accompanying such depressive effect on state 3 respiration as observed for emestrin.

Genotoxicity in the hepatocyte/DNA repair test and toxicity to liver mitochondria of 1-hydroxyanthraquinone and several dihydroxyanthraquinones

1-Hydroxyanthraquinone and dihydroxyanthraquinones (alizarin, quinizarin, anthrarufin and chrysazin) were examined for genotoxicity in the hepatocyte/DNA repair test and for effects on oxidative phosphorylation in isolated rat liver mitochondria. Of the anthraquinone compounds tested, 1-hydroxyanthraquinone and 1,8-dihydroxyanthraquinone (chrysazin) induced DNA repair synthesis in rat hepatocytes, indicating their genotoxic activity. Only 1,2-dihydroxyanthraquinone (alizarin) exerted an uncoupling and inhibitory effect on mitochondrial respiration. The possible relationships of the genotoxic potencies and the uncoupling activities of these anthraquinones to their chemical structures are discussed.

Cytotoxicity and genotoxicity of xenoclauxin and desacetyl duclauxin from Penicillium duclauxii (Delacroix)

The duclauxin derivatives xenoclauxin and desacetylduclauxin were examined for their effects on the growth of L-1210 murine leukemia cells, on the induction of DNA repair in the rat and mouse hepatocyte primary culture (HPC/DNA repair test), and on oxidative phosphorylation in mitochondria from rat livers in comparison to duclauxin. Both derivatives inhibited the growth of L-1210 culture cells as strongly as duclauxin. Duclauxin derivatives were negative in the HPC/DNA repair test. Xenoclauxin exhibited a potent uncoupling effect accompanying a marked depression of state 3 respiration of mitochondria in a similar fashion to that of duclauxin. Desacetylduclauxin significantly inhibited the state 3 respiration without causing uncoupling of oxidative phosphorylation in mitochondria. These results strongly suggest that xenoclauxin and desacetylduclauxin from Penicillium duclauxii are not genotoxic but are cytotoxic mainly due to their potent inhibition of ATP synthesis in mitochondria.

Inhibitory effect of sterigmatocystin and 5,6-dimethoxysterigmatocystin on ATP synthesis in mitochondria

The inhibitory effects of sterigmatocystin, O-methylsterigmatocystin, and 5,6-dimethoxysterigmatocystin on the ATP synthesis system in mitochondria were compared with that of aflatoxin B1, which disturbs the respiratory chain in mitochondria. Sterigmatocystin and 5,6-dimethoxysterigmatocystin were found to uncouple the oxidative phosphorylation process without causing depression of state 3 respiration. O-Methylsterigmatocystin did not exhibit uncoupling activity at the limited concentrations tested (due to its low solubility in an aqueous system). These compounds, as well as aflatoxin B1, elicited neither pseudo-energized nor energized swelling of mitochondria and did not inhibit Ca2+-induced swelling of mitochondria.

Inhibition by secalonic acid D of oxidative phosphorylation and Ca2+-induced swelling in mitochondria isolated from rat livers

The in vitro biological activity of secalonic acid D, a mycotoxin from Aspergillus ochraceus, was studied to assess its cytotoxicity for isolated rat liver mitochondria. Secalonic acid D uncoupled the oxidative phosphorylation of mitochondria and caused a mild inhibition of state 3 respiration. Secalonic acid D weakly enhanced latent ATPase activity in mitochondria but suppressed 2,4-dinitrophenol-stimulated ATPase activity. Secalonic acid D did not induce pseudoenergized swelling of mitochondria and markedly inhibited the Ca2+-induced swelling of mitochondria in KCl isotonic solution.