Plasma concentration of uroguanylin in patients on maintenance dialysis therapy

BACKGROUND: Uroguanylin, originally isolated from urine, is a new natriuretic peptide. Its plasma level is increased in association with renal impairment and fluid retention in patients with renal diseases. METHODS: Uroguanylin concentrations were measured in patients on hemodialysis (HD, n = 76) and those on continuous ambulatory peritoneal dialysis (CAPD, n = 10) using a sensitive ra- dioimmunoassay for human uroguanylin. RESULTS: Plasma concentrations of immunoreactive (ir)-uroguanylin in the patients on HD and CAPD (212.0 +/- 17.4 and 245.3 +/- 39.5 fmol/ml) were significantly higher than the value for the normal controls (5.0 +/- 0.3 fmol/ml). Plasma ir-uroguanylin levels before the start of regular HD were correlated with predialysis excess weight based on their dry weights (r = 0.33, p < 0.01) and with dialysis duration (r = 0.26, p < 0.05). The plasma levels in patients with HD, for whom high-flux membranes were used, were decreased at the end of regular HD as compared with the prior levels (p < 0.05), but not in those who underwent HD with conventional membranes. CONCLUSION: These findings suggest that the plasma ir-uroguanylin level is related to the patient's volume status as well as renal impairment. Whether the accumulation of uroguanylin has a pathological effect has yet to be determined.     

Homotypic Adhesion through Carcinoembryonic Antigen Plays a Role in Hepatic Metastasis Development

We established a cell line with high metastatic potential to the liver (LS-LM4) after four successive repetitions of splenic injection of liver-metastatic cells in SCID mice. This cell line strongly expressed CEA and showed increased homotypic adhesion as compared with the parent cell line (LS174T). To examine the role of CEA in the increased homotypic adhesion, LS-LM4 cells were treated with anti-CEA antibody and subjected to an in vitro adhesion and aggregation assay. Further, to study the role of CEA in the hepatic metastasis of cells with high metastatic potential, LS-LM4 cells were treated with anti-CEA antibody, and the inhibition of hepatic metastasis after splenic injection in vivo was examined. There was a 62% decrease in the homotypic adhesion of anti-CEA antibody-treated (100 μg/ml) LS-LM4 cells under a Ca²⁺-free condition as compared with the control ( P <0.01). Anti-CEA antibody (100 μg/ml) inhibited cell aggregation under a Ca²⁺-free condition ( P <0.05). Treatment with anti-E-cadherin antibody (60 μ/ml) plus anti-CEA antibody (100 μg/ml) inhibited cell aggregation more potently than anti-E-cadherin antibody treatment alone in the presence of Ca²⁺. In vivo , there was a 75% decrease in the number of hepatic metastatic nodules in the G125 anti-CEA antibody-treated group as compared with the control group ( P <0.01). Similarly, there was a 40% decrease in the diameter of metastatic nodules and there was a 90% decrease in total tumor volume of hepatic metastasis in the G125 anti-CEA antibody-treated group as compared with the control ( P <0.01). These results suggest that increased metastatic potential to the liver is at least partly due to increased homotypic binding mediated by CEA.     

Association of Loss of Heterozygosity at the p53 Locus with Chemoresistance in Osteosarcomas

Although the osteosarcoma is considered to be among the most chemosensitive malignancies and preoperative chemotherapy is commonly applied, an appreciable proportion of cases are in fact quite insensitive. Predictive markers for chemosensitivity are therefore desirable in order to develop effective treatment strategies. Thirty-two cases of conventional osteosarcomas treated at the Cancer Institute Hospital, Tokyo, were analyzed. The sensitivity to preoperative chemotherapy was investigated with reference to loss of heterozygosity (LOH) at the 17p13 ( p 53) and 13q14 ( Rb ) loci and expression of the cell-cycle associated proteins, p53, Rb, p21/Waf-1, mdm-2 and Ki-67, as detected immunohistochemically. LOH was detected by analyzing polymerase chain reaction products at marker microsatellite loci. The efficacy of chemotherapy was evaluated both radiologically and histologically. LOH at p 53 or Rb loci was seen in 54% (13/24) and 58% (14/24) of cases, respectively. Only 15% of osteosarcomas with LOH at the p 53 locus were sensitive to preoperative chemotherapy, as compared to 64% of tumors without such loss ( P <0.05). A similar but much less distinct tendency was observed with LOH at the Rb locus. No relationship was evident between chemosensitivity and immunohistochemical staining patterns for p53, Rb, p21/Waf-1, mdm-2 or Ki-67. The results suggest that p 53 gene deletion, but not the other parameters investigated, may be useful for predicting chemoresistance of osteosarcomas.     

Somatic Mutations of the PTEN/MMAC1 Gene in Fifteen Japanese Endometrial Cancers: Evidence for Inactivation of Both Alleles

Loss of heterozygosity (LOH) of chromosome 10q is observed in approximately 40% of endometrial cancers. Mutations in PTEN/MMAC1 , a gene recently isolated from the 10q23 region, are responsible for two dominantly inherited neoplastic syndromes, Cowden disease and Bannayan-Zonana syndrome. Somatic mutations of this gene have also been detected in sporadic cancers of the brain, prostate and breast. To investigate the potential role of this putative tumor suppressor gene in endometrial carcinogenesis as well, we examined 46 primary endometrial cancers for LOH at the 10q23 region, and for mutations in the entire coding region and exon-intron boundaries of the PTEN/MMAC1 gene. LOH was identified in half of the 38 informative cases, and subtle somatic mutations were detected in 15 tumors (33%). Our results suggest that of the genes studied so far in endometrial carcinomas, PTEN/MMAC1 is the most commonly mutated one, and that inactivation of both copies by allelic loss and/or mutation, a pattern that defines genes as "tumor suppressors,'contributes to tumorigenesis in endometrial cancers.     

P-glycoprotein plays a major role in the efflux of fexofenadine in the small intestine and blood-brain barrier, but only a limited role in its biliary excretion.

Fexofenadine is a selective, nonsedating H(1)-receptor antagonist approved for symptoms of allergic conditions, which is mainly excreted into feces via biliary excretion. The purpose of this study is to investigate its pharmacokinetics in mice and rats to determine the role of P-glycoprotein (P-gp) in its biliary excretion. In mice, biliary excretion clearance (17 ml/min/kg) accounted for almost 60% of the total body clearance (30 ml/min/kg). Comparing the pharmacokinetics after intravenous and oral administration indicated that the bioavailability of fexofenadine was at most 2% in mice. Knockout of Mdr1a/1b P-gp did not affect the biliary excretion clearance with regard to both plasma and liver concentrations, whereas the absence of P-gp caused a 6-fold increase in the plasma concentration after oral administration. In addition, the steady-state brain-to-plasma concentration ratio of fexofenadine was approximately 3-fold higher in Mdr1a/1b P-gp knockout mice than in wild-type mice. Together, these results show that P-glycoprotein plays an important role in efflux transport in the brain and small intestine but only a limited role in biliary excretion in mice. In addition, there was no difference in the biliary excretion between normal and hereditarily multidrug resistance-associated protein 2 (Mrp2)-deficient mutant rats (Eisai hyperbilirubinemic rats) and between wild-type and breast cancer resistance protein (Bcrp) knockout mice. These results suggest that the biliary excretion of fexofenadine is mediated by unknown transporters distinct from P-gp, Mrp2, and Bcrp.     

Metabolism and disposition of a potent group II metabotropic glutamate receptor agonist, in rats, dogs, and monkeys.

Metabolism and disposition of MGS0028 [(1R,2S,5S,6S)-2-amino-6-fluoro-4-oxobicyclo[3.1.0]hexane-2,6-dicarboxylic acid monohydrate], a potent group II metabotropic glutamate receptor agonist, were examined in three preclinical species (Sprague-Dawley rats, beagle dogs, and rhesus monkeys). In rats, MGS0028 was widely distributed and primarily excreted in urine as parent and as a single reductive metabolite, identified as the 4R-isomer MGS0034 [(1R,2S,4R,5S,6S)-2-amino-6-fluoro-4-hydroxybicyclo[3.1.0]-hexane-2,6-dicarboxylic acid]. MGS0028 had a low brain to plasma ratio at efficacious doses in rats and was eliminated more slowly in rat brain than in plasma. Exposure increased proportionally (1--10 mg/kg p.o.) in rats, with bioavailability>60% at all doses. However, bioavailability was only approximately 20% in monkeys, and MGS0034 was found in relatively high abundance in plasma. In dogs, oral bioavailability was >60%, and the metabolite was not detected. In vitro metabolism was examined in liver subcellular fractions (microsomes and cytosol) from rat, dog, monkey, and human. Reductive metabolism was observed in rat, monkey, and human liver cytosol incubations, but not in dog liver cytosol incubations. No metabolism of MGS0028 was detected in incubations with liver microsomes from any species. Similar to in vivo results, MGS0028 was reduced in cytosol stereospecifically to MGS0034. The rank order of in vitro metabolite formation (monkey > rat approximately human > dog) was in agreement with in vivo observations in rats, dogs, and monkeys. Based on the observation of species difference in reductive metabolism, rat and monkey were recommended to be the preclinical species for further characterization prior to testing in humans. Finally, allometric scaling predicts that human pharmacokinetic parameters would be acceptable for further development.     

Practice variation in perioperative antibiotic use in Japan.

OBJECTIVE: Under the fee-for-service system, the overuse and misuse of perioperative antibiotics have become serious concerns in Japan. The objective of the present study is to investigate practice variations of perioperative antimicrobial prophylaxis between and within hospitals, and to identify any opportunities for improvement. METHODS: We polled 319 surgeons in six specialties employed by 11 teaching hospitals in Japan. We developed questionnaires with vignettes, asking physicians about their practice of antimicrobial prophylaxis in six surgical procedures (gastrectomy, hysterectomy, cataract surgery, clipping of cerebral aneurysm, hip fracture surgery, and coronary artery bypass graft) and utilization of institutional clinical pathways. RESULTS: Average durations of prophylaxis varied by procedure, from 1.6 days for cataract surgery to 5.8 days for clipping surgery. Variation was also observed between institutions for the same procedure, e.g. institutional averages for the duration of prophylaxis for gastrectomy ranged from 2.3 to 7 days. Large intra-institutional variation in prophylaxis duration and inconsistent use of clinical pathways were observed in the cases of gastrectomy, hip fracture surgery, and clipping surgery. At one hospital, 20% of physicians performing gastrectomy indicated the use of an institutional clinical pathway, and prophylaxis duration ranged from 3 to 6 days. For cataract surgery and hysterectomy, clinical pathways were universally applied and intra-institutional practice variation was small, yet prophylaxis duration varied widely between hospitals and third-generation cephalosporins were used extensively. Average length of prophylaxis for hysterectomy ranged from 1.8 to 6 days and 43% of respondents prescribed third-generation cephalosporins. CONCLUSIONS: In Japan, perioperative antimicrobial prophylaxis lacks standardization. Efforts to strengthen an evidence-based approach to antimicrobial prophylaxis need to be made a priority at both the national and institutional levels.     

Functional involvement of rat organic anion transporter 2 (Slc22a7) in the hepatic uptake of the nonsteroidal anti-inflammatory drug ketoprofen.

Rat organic anion transporter 2 (rOat2, Slc22a7) is a sinusoidal multispecific organic anion transporter in the liver. The role of rOat2 in the hepatic uptake of drugs has not been thoroughly investigated yet. rOat2 substrates include nonsteroidal anti-inflammatory drugs, such as ketoprofen, indomethacin, and salicylate. In the present study, the uptake of ketoprofen, indomethacin, and salicylate by freshly isolated rat hepatocytes was characterized. The uptake of ketoprofen, indomethacin, and salicylate by hepatocytes was sodium-independent, and the rank order of their uptake activities was indomethacin > ketoprofen > salicylate. Kinetic analysis based on Akaike's Information Criterion suggested that the uptake of ketoprofen and indomethacin by hepatocytes consists of two saturable components and one nonsaturable one. The K(m) and V(max) values for the high- and low-affinity components for ketoprofen uptake were 0.84 and 97 microM and 35 and 1800 pmol/min/mg protein, respectively, whereas those for indomethacin were 1.1 and 140 microM and 130 and 16,000 pmol/min/mg protein, respectively. The K(m) values of the high-affinity component were similar to those for rOat2 (3.3 and 0.37 microM for ketoprofen and indomethacin, respectively). The uptake of ketoprofen by hepatocytes was significantly inhibited by probenecid and rOat2 inhibitors (indocyanine green, indomethacin, glibenclamide, and salicylate). Other inhibitors of rOatps (taurocholate and pravastatin) and rOat3 (pravastatin and p-aminohippurate) had a slight effect, but digoxin had no effect. These results suggest that rOat2 accounts partly for the hepatic uptake of ketoprofen and, presumably, indomethacin as a high-affinity site and that other transporters, such as rOatps, but not rOatp2, and rOat3, are also involved.     

Overexpression of the aldo-keto reductase family protein AKR1B10 is highly correlated with smokers' non-small cell lung carcinomas.

PURPOSE: Squamous cell carcinoma (SCC) and adenocarcinoma of the lung are currently subject to similar treatment regimens despite distinct differences in histology and epidemiology. The aim of this study is to identify a molecular target with diagnostic and therapeutic values for SCC. EXPERIMENTAL DESIGN: Genes specifically up-regulated in SCC were explored through microarray analysis of 5 SCCs, 5 adenocarcinomas, 10 small cell lung carcinomas, 27 normal tissues, and 40 cancer cell lines. Clinical usefulness of these genes was subsequently examined mainly by immunohistochemical analysis. RESULTS: Seven genes, including aldo-keto reductase family 1, member B10 (AKR1B10), were identified as SCC-specific genes. AKR1B10 was further examined by immunohistochemical analysis of 101 non-small cell lung carcinomas (NSCLC) and its overexpression was observed in 27 of 32 (84.4%) SCCs and 19 of 65 (29.2%) adenocarcinomas. Multiple regression analysis showed that smoking was an independent variable responsible for AKR1B10 overexpression in NSCLCs (P < 0.01) and adenocarcinomas (P < 0.01). AKR1B10 staining was occasionally observed even in squamous metaplasia, a precancerous lesion of SCC. CONCLUSION: AKR1B10 was overexpressed in most cases with SCC, which is closely associated with smoking, and many adenocarcinoma cases of smokers. These results suggest that AKR1B10 is a potential diagnostic marker specific to smokers' NSCLCs and might be involved in tobacco-related carcinogenesis.     

Green tea component, catechin, induces apoptosis of human malignant B cells via production of reactive oxygen species.

PURPOSE: Green tea polyphenol, (-)-epigallocatechin-3-gallate, has been shown to inhibit cellular proliferation and induce apoptosis of various cancer cells. The aim of this study was to investigate the possibility of (-)-epigallocatechin-3-gallate as a novel therapeutic agent for the patients with B-cell malignancies including multiple myeloma. EXPERIMENTAL DESIGN: We investigated the effects of (-)-epigallocatechin-3-gallate on the induction of apoptosis in HS-sultan as well as myeloma cells in vitro and further examined the molecular mechanisms of (-)-epigallocatechin-3-gallate-induced apoptosis. RESULTS: (-)-Epigallocatechin-3-gallate rapidly induced apoptotic cell death in various malignant B-cell lines in a dose- and time-dependent manner. (-)-Epigallocatechin-3-gallate-induced apoptosis was in association with the loss of mitochondrial transmembrane potentials (Deltapsim); the release of cytochrome c, Smac/DIABLO, and AIF from mitochondria into the cytosol; and the activation of caspase-3 and caspase-9. Elevation of intracellular reactive oxygen species (ROS) production was also shown during (-)-epigallocatechin-3-gallate-induced apoptosis of HS-sultan and RPMI8226 cells as well as fresh myeloma cells. Antioxidant, catalase, and Mn superoxide dismutase significantly reduced ROS production and (-)-epigallocatechin-3-gallate-induced apoptosis, suggesting that ROS plays a key role in (-)-epigallocatechin-3-gallate-induced apoptosis in B cells. Furthermore, a combination with arsenic trioxide (As2O3) and (-)-epigallocatechin-3-gallate significantly enhanced induction of apoptosis compared with As2O3 alone via decreased intracellular reduced glutathione levels and increased production of ROS. CONCLUSIONS: (-)-Epigallocatechin-3-gallate has potential as a novel therapeutic agent for patients with B-cell malignancies including multiple myeloma via induction of apoptosis mediated by modification of the redox system. In addition, (-)-epigallocatechin-3-gallate enhanced As2O3-induced apoptosis in human multiple myeloma cells.