Yoko Ohtsuka

Cytochrome P450 4A expression and arachidonic acid omega-hydroxylation in the kidney of the spontaneously hypertensive rat.

20-Hydroxyeicosatetraenoic acid (20-HETE) is a major arachidonate metabolite in the kidney of the spontaneously hypertensive rat (SHR). The increase in its synthesis has been associated with the elevation of blood pressure in the SHR. The omega-hydroxylation of arachidonic acid is an activity associated with members of the CYP4A gene family which, in the rat, comprises three major isoforms: 4A1, 4A2 and 4A3. 20-HETE displays potent and diverse biological activities which can affect pro- and anti-hypertensive mechanisms dependent upon where, when and by which isoform it has been produced. Therefore, it is important to identify and characterize its biosynthetic system. We compared CYP4A mRNA and protein expression to patterns of 20-HETE synthesis in the SHR kidney. The reverse transcription/polymerase chain reaction (RT/PCR) technique was used to amplify CYP4A mRNA in microdissected nephron segments. Southern blot hybridization of PCR products obtained from nephron segments with the CYP4A1 cDNA probe demonstrated strong signals in S2 and S3 segments of the proximal tubule. Immunoblots of nephron segments using a polyclonal anti-rat liver CYP4A1 antibody which cross-reacts with CYP4A2 and CYP4A3, and 14C-arachidonic acid metabolism, confirmed that arachidonic acid omega-hydroxylation, i.e., 14C-20HETE formation, and CYP4A proteins were also localized mainly in the S2 and S3 segments. Correlation also existed between the age-dependent increase in arachidonate omega-hydroxylation in the kidney and CYP4A mRNA levels as measured by Northern hybridization of total RNA using the CYP4A1 cDNA probe. Immunoblot analysis revealed that at 7 weeks, where 20-HETE production is at its maximum, all three proteins are expressed. CYP4A3 and 4A1 immunoreactive proteins appeared at 3 weeks, showed maximum levels at 5 and 7 weeks, respectively, and gradually decreased to lower levels at 13 and 20 weeks, whereas CYP4A2 levels were undetectable at 3, 5 and 7 weeks but appeared at 13-20 weeks. Additional immunoblots indicated that renal cortical CYP4A1 protein levels were higher in SHR compared to Sprague-Dawley and Wistar-Kyoto rats. The increased levels of CYP4A1-immunoreactive band at 7 weeks corresponded to the maximal activity of arachidonate omega-hydroxylation. Thus, CYP4A1 might play a significant role in contributing to the increased cortical/proximal production of 20-HETE seen in 7-week-old SHR. However, given the high homology among members of the CYP4A gene family and the lack of specific tools to discern among these isoforms, additional studies have to be carried out to substantiate our findings.

Quenching the Thirst in Dialysis Patients

In a double-blind cross-over trial, 22 stable end-stage renal failure patients on maintenance haemodialysis were subjected to conventional dialysis with dialysate containing 137 mEq/l sodium and constant ultrafiltration (UF) and to a different dialysis therapy, in which, by linear sodium modelling, the dialysate sodium was reduced from 137 to 128 mEq/l. A computerized UF program was used to gradually reduce the UF to a minimum towards the end of the session. Severity of thirst, interdialytic weight gain and intradialytic complications were less with low sodium dialysate. It allowed adequate UF with absolute hemodynamic stability. The reduced incidence of complication with low sodium dialysate therapy was probably because they required less UF.

Angiography with Nonionic X-Ray Contrast Media in Severe Chronic Renal Failure: Renal Function and Contrast Retention

The effects of contrast media on renal function and the cortical retention of contrast media after abdominal angiography were investigated. Sixteen nondiabetic patients with predialytic chronic renal failure received either the nonionic dimeric contrast medium iodixanol or the monomeric contrast medium iohexol in a double-blind randomized study. All patients were well hydrated before, during and after angiography. Mean 99mTc-DTPA clearance was 14.0 ml/min/1.73 m2 in the iodixanol group, and 9.3 ml/min/1.73 m2 in the iohexol group at baseline. No statistically significant changes were seen after angiography. Serum creatinine increased significantly 48 and 72 h after angiography in both groups, and then normalized. Creatinine clearance was reduced only in the iohexol group, at 72-96 h. The urinary excretion of renal enzymes and of total protein did not change significantly. No patients developed oliguria or required dialysis during the 7-day observation period. Increased attenuation in the renal cortex, measured by computed tomography and probably reflecting intracellular retention of contrast medium, peaked at 24 h, and was observed in both groups during the follow-up period. Thus, although transient and minor changes in glomerular filtration rate were noted, both iodixanol and iohexol were safe for use in angiography in nondiabetic patients with severe chronic failure when the patients were well hydrated.

Oxyphil Cell Function in Secondary Parathyroid Hyperplasia

Oxyphil cell function in secondary parathyroid hyperplasia due to chronic renal failure was evaluated using in situ hybridization and heterotransplantation of parathyroid tissue. In situ hybridization and histologic analysis were performed on continuous frozen sections using 22 parathyroid tissues. A restricted area composed exclusively of oxyphil cells was observed in 10 specimens, and an area of only chief cells was found in 12 specimens. Silver grains demonstrating the existence of parathyroid hormone (PTH) mRNA were 18.8 +/- 7.8 (mean +/- SD) in oxyphil cells while those in chief cells were 17.2 +/- 7.5. PTH mRNA was abundant in both the oxyphil and chief cells. Further analysis of oxyphil cell function was assessed by the heterotransplantation of parathyroid nodules, consisting exclusively of oxyphil or chief cells, into nude mice. The function of these implants was assessed by measuring the concentration of human intact PTH which did not cross-react with mouse PTH. Serum PTH concentrations were correlated with the volume of implanted tissue. Elevations of PTH concentrations were similar in the mice transplanted with oxyphil or chief cells, indicating that both cell types had similar PTH secretory activity. The basic histologic characteristics of both cell types were not altered following transplantation. These results demonstrate that oxyphil cells in secondary parathyroid hyperplasia synthesize and secrete PTH, and that this secretion contributes to the pathophysiology of hyperparathyroidism.

A Case of Chronic Graft-versus-Host Disease following Living-Related Donor Kidney Transplantation

A 25-year-old man with a 2.5-year history of maintenance hemodialysis underwent a living-related donor (father) kidney transplantation. He was free from acute rejection, but 8 months after the kidney transplantation, he complained of malaise and fever which were accompanied by eruptions on the face, fingers, and hips which resembled symptoms seen in patients suffering from systemic vasculitis. Skin biopsy findings were compatible with those of chronic graft-versus-host disease (GVHD). The human leukocyte antigen (HLA) family study disclosed that the donor’s HLA haplotype was homozygous and identical to one of the recipient’s HLA haplotypes which indicated that the host would not resist engraftment. On the basis of these findings, a diagnosis of chronic GVHD was made, and increasing doses of immunosuppressants resulted in a resolution of these symptoms. Our report is the first describing GVHD that developed in a patient undergoing related-donor kidney transplantation.

Hypophosphatemia in End Stage Renal Disease

A case of hypophosphatemia in a 55-year-old black female on maintenance hemodialysis is described. She developed multiple bone fractures and congestive heart failure during her 10-year period on hemod

Membranous nephropathy complicating adenolymphoma of the parotid (Warthin's tumour).

Membranous nephropathy has been described in association with many malignancies including various lymphomas. However, it has not been previously described as a complication of benign solid adenolymphoma of the parotid, also called Warthins tumour. We describe a patient who presented with an adenolymphoma of the parotid, and developed a severe nephrotic syndrome due to membranous nephropathy 6 months after the parotid swelling. The nephrotic syndrome resolved following parotidectomy and a short course of immunosuppression with prednisolone and cyclophosphamide. The possible pathophysiologic mechanisms are discussed.

Significance of lymphocyte fatty acid changes in chronic renal failure

In the present study we describe fatty acid fluctuations in peripheral blood lymphocytes of patients with chronic renal failure who were undergoing maintenance hemodialysis. The decreased concentrations of linoleic acid and arachidonic acid and the increase in stearic acid are discussed in relation to the lymphocyte immune response and lymphocyte membrane enzymic systems in the disease.

Sudden Death or Refractory Pleural Effusion following Treatment with Granulocyte Colony-Stimulating Factor in Two Hemodialysis Patients

Accessible online at: http://BioMedNet.com/karger Dear Sir, Since clinical utilization of granulocyte colony-stimulating factor (G-CSF) has increased, rare and severe systemic adverse effects have been reported [1–3]. We report 2 cases of hemodialysis (HD) patients treated with G-CSF for drug-induced granulocytopenia, 1 of whom suddenly died during HD and the other developed refractory pleural effusion during neutrophil recovery and then an unexplainable leukopenia and thrombocytopenia. Case 1. A 70-year-old woman with a 6year history of rheumatoid arthritis (RA) was admitted in January 1997 for the evaluation of acute hyperuricemic renal failure and granulocytopenia associated with mizoribine (Asahikasei, Tokyo, Japan) treatment for RA. On admission, laboratory test revealed a hematocrit 21%, a white blood cell (WBC) count 700/Ìl with 21% neutrophils and a platelet count 198,000/Ìl. The blood urea nitrogen (BUN) was 151 mg/dl, serum creatinine (Cr) 4.1 mg/dl, serum uric acid 26.0 mg/dl. Electrocardiogram showed normal sinus rhythm. Mizoribine was discontinued and she was begun on daily subcutaneous administration of G-CSF (100 Ìg, 3 Ìg/kg daily) for 5 days. Hemodialysis (HD) using the biocompatible polymethylmethacrylate (PMMA) hollow fiber and bicarbonate dialysate was instituted, and nafamostat Fig. 1. Clinical course of case 2. HD = Hemodialysis; IPD = intermittent peritoneal dialysis; MTX = methotrexate; PSL = prednisolone; mPSL = methylprednisolone pulse therapy; G-CSF = granulocyte colony-stimulating factor; WBC = white blood cell; Plt = platelet. HD

Sex Chromosomes Do Not Influence Renal Injury in Borderline Hypertensive Rats

The present study was undertaken to investigate whether the development of proteinuria in the borderline hypertensive rat (BHR) is influenced by the Y chromosome and to determine if the onset of prote