A common polymorphism in the tissue kallikrein gene is associated with increased urinary excretions of calcium and sodium in Japanese volunteers.

Tissue kallikrein is an enzyme involved in the release of kinin in peripheral tissues. It is believed to regulate hemodynamics and electrolyte transport in the kidney. The present study analyzed polymorphisms of tissue kallikrein in Japanese volunteers and examined the associations between allele H in the promoter region, which has been shown to have decreased promoter activity, and urinary kallikrein activity and physiological parameters in subjects on an ad libitum diet. Ninety and 73 volunteers were analyzed for the promoter and coding regions of the tissue kallikrein gene, respectively. The allelic frequency of allele H was found to be 24%. One synonymous and three non-synonymous polymorphisms were found in the coding regions. Urinary kallikrein activity was not significantly decreased in subjects with allele H compared to those without allele H, although they were low in two homozygotes of allele H. Urinary excretions of calcium and sodium were larger in the subjects with allele H than in those without. It is concluded that allele H is a common polymorphism in Japanese and may contribute to decreased reabsorptions of calcium and sodium in the kidney. Further interventional studies are needed to clarify the phenotype of allele H with respect to renal electrolyte handling.

In vivo kinetics of indoxyl sulfate in humans and its renal interaction with angiotensin-converting enzyme inhibitor quinapril in rats.

Indoxyl sulfate (IS) is an organic anion uremic toxin that accumulates in patients with chronic kidney disease (CKD). The aims of this study were to examine the kinetic profiles of IS in humans at a steady state after multiple doses of L-Trp, a precursor of IS, and the in vivo interaction of IS with the angiotensin-converting enzyme inhibitor quinapril, whose active metabolite is a substrate of organic anion transporter 3 (OAT3) in rats. First, 12-h kinetics after single doses of Trp (2, 4, and 8 g) were examined in two healthy volunteers. Second, 24-h kinetics after a single dose of 2 g of Trp was studied in six volunteers. Third, 35-h kinetics after single and multiple doses of 2 g of Trp were examined in five volunteers. In anesthetized rats, quinapril or probenecid, an inhibitor of OATs, was given intravenously before IS, and blood and urine samples were taken until 90 min. Trp and IS concentrations were determined by high-performance liquid chromatography. Ultrafiltration was used to measure serum unbound IS concentrations. Renal tubular secretion of IS accounted for more than 90% of its renal clearance in the steady state of serum IS levels after multiple doses in humans. In animals, the serum area under the curve of IS increased in conjunction with a decrease in renal clearances after coadministration of IS with quinapril or probenecid. It is concluded that quinapril may inhibit the urine excretion of IS via OAT3-mediated renal tubular transport in patients with CKD.

Contribution of down-regulation of intestinal and hepatic cytochrome P450 3A to increased absorption of cyclosporine A in a rat nephrosis model.

This study examined the contribution of changes in regulation of intestinal and hepatic cytochrome P450 3A (CYP3A) and multidrug resistance transporter 1 (Mdr1) to absorption of cyclosporine A (CsA) in a rat nephrosis model. Interleukin (IL)-6 was also measured. Puromycin aminonucleoside at a dose of 20 mg/100 g was administered intravenously. Tissue samples were dissected out from the upper and middle intestines and liver after development of nephrosis to measure the expression levels of mRNA and protein. CsA at a dose of 0.5 mg/100 g was administered into a closed loop of the upper and middle intestines. Blood from the inferior vena cava (IVC) and portal vein was taken until 30 min after administration. The expression levels of CYP3A decreased markedly, whereas those of Mdr1 showed large interindividual variations for all of the tissues in the nephrotic rats. Plasma concentrations of CsA reached higher levels in the nephrotic than in the control rats and were higher when administered from the upper than the middle intestine in both the portal vein and IVC. IL-6 increased in urine in the nephrotic rats. In summary, intestinal and hepatic CYP3A were down-regulated in the nephrosis model accompanying the increased levels of IL-6. Consistent results were not obtained for the regulation of Mdr1. In conclusion, these findings suggest that the down-regulation of CYP3A in the upper intestine and liver predominantly contributes to the increase in CsA absorption, and Mdr1 showed less contribution in this rat nephrosis model.

Usefulness of MRI compared with CT for diagnosis of mesenteric lymphoma in a dog.

We evaluated the usefulness of MRI and compared it with CT for diagnosis of mesenteric lymphoma in a dog. The results in the plain CT, dynamic CT and plain MR (T1WI and T2WI) images suggested that the mass was a large single nodular lesion with abundant blood perfusion. On enhanced MRI(T1WI) , the mass was depicted as a tumor with adhesion to the gut wall. Exploratory laparotomy confirmed the mass was consistent with the findings on enhanced MRI. We think that MRI might be a useful imaging tool for diagnosis of canine mesenteric lymphoma.

Unique characteristics of rectal carcinoma cell lines derived from invasive carcinomas in ulcerative colitis patients.

To identify the characteristics of ulcerative colitis (UC)-associated carcinomas, 8 lesions, high-grade dysplasias and invasive carcinomas, were implanted into severely combined immunodeficient (SCID) mice and/or cultured in vitro. Intramucosal neoplasias consisting of high-grade dysplasia showed extremely slow proliferation after implantation (2/3 cases) and in vitro culture failed (4 cases). However, invasive carcinomas demonstrated rapid growth both after SCID mouse implantation and in vitro (4/4 cases). From two cases of invasive carcinomas, 6 cell lines were established, and these are the first to be described in the literature. In addition to variation in immunohistochemically determined phenotypic expression regarding alpha-fetoprotein, chromogranin A and estrogen receptors, the established cell lines showed varying differentiation (moderately or poorly differentiated adenocarcinoma, adenosquamous carcinoma and poorly differentiated adenocarcinoma with multinuclear giant cells and bone formation). The results are in contrast with findings for sporadic colorectal carcinomas. Although the prevalence of DNA alterations is not frequent, loss of heterozygosity (17p and 18q) and deletion of exons 8 to 11 in DPC-4 were revealed in all of 6 cell lines, suggesting relatively high genetic instability. We found loss or translocation of many chromosomes (#3, 5, 6, 8, 10, 11, 13, 16, 17, 18 and 19) other than chromosomes 1, 5, 8, 11, 13, 17 and 18, which are frequently involved in sporadic colorectal carcinoma cell lines. Thus, the established cell lines may be good models of tumorigenesis and progression in the chronic inflammation-carcinoma sequence.