Prediction of human liver microsomal oxidations of 7-ethoxycoumarin and chlorzoxazone with kinetic parameters of recombinant cytochrome P-450 enzymes.

Different roles of individual forms of human cytochrome P-450 (CYP) in the oxidation of 7-ethoxycoumarin and chlorzoxazone were investigated in liver microsomes of different human samples, and the microsomal activities thus obtained were predicted with kinetic parameters obtained from cDNA-derived recombinant CYP enzymes in microsomes of Trichoplusia ni cells. Of 14 forms of recombinant CYP examined, CYP1A1 had the highest activities (V(max)/K(m) ratio) in catalyzing 7-ethoxycoumarin O-deethylation followed by CYP1A2, 2E1, 2A6, and 2B6, although CYP1A1 has been shown to be an extrahepatic enzyme. With these kinetic parameters (excluding CYP1A1) we found that CYP1A2 and 2E1 were the major enzymes catalyzing 7-ethoxycoumarin; the contributions of these two forms were dependent on the contents of these CYPs in liver microsomes of different humans. Similarly, chlorzoxazone 6-hydroxylation activities of liver microsomes were predicted with kinetic parameters of recombinant human CYP enzymes and it was found that CYP3A4 as well as CYP1A2 and 2E1 were involved in chlorzoxazone hydroxylation, depending on the contents of these CYP forms in the livers. Recombinant CYP2A6 and 2B6 and CYP2D6 had considerable roles (V(max)/K(m) ratio) for 7-ethoxycoumarin O-deethylation and chlorzoxazone 6-hydroxylation, respectively; however, these CYP forms had relatively minor roles in the reactions, probably due to low expression in human livers. These results support the view that the roles of individual CYP enzymes in the oxidation of xenobiotic chemicals in human liver microsomes could be predicted by kinetic parameters of individual CYP enzymes and by the levels of each of the CYP enzymes in liver microsomes of human samples.     

Distribution of connectin (titin), nebulin and α-actinin at myotendinous junctions of chicken pectoralis muscles: an immunofluorescence and immunoelectron microscopic study

Summary The distribution of connectin (titin), nebulin and -actinin in the areas of myotendinous junctions of chicken pectoralis muscles was examined by immunocytochemical methods. Staining with antibodies against connectin (4C9, SM1 and P1200) and nebulin formed doublets flanking nonterminal Z-bands; near the end of muscle fibres singlets were seen within the terminal sarcomere on the side adjacent to the terminal Z-bands. The apical regions of muscle processes, where no myosin filaments are present although actin filaments exist, were reactive with anti-nebulin but not with anti-connection. Antibodies against pectoralis (skeletal muscle type) -actinin stained non terminal Z-bands and that against gizzard (smooth muscle type) the sarcolemma. Terminal Z-bands were unreactive with both of these antibodies. These findings indicate that, although terminal and nonterminal Z-bands differ in their molecular composition, connectin and nebulin filaments appear to link myosin and actin filaments, respectively, to both Z-band types.     

Development of a possible nonmammalian test system for radiation-induced germ-cell mutagenesis using a fish, the Japanese medaka (Oryzias latipes).

To develop a specific-locus test (SLT) system for environmental mutagenesis using vertebrate species other than the mouse, we first established a tester stock of the fish medaka (Oryzias latipes) that is homozygous recessive at three loci. The phenotypic expression of these loci can be easily recognized early in embryonic development by observation through the transparent egg membrane. We irradiated wild-type males with 137Cs gamma-rays to determine the dose-response relationships for dominant lethal and specific-locus mutations induced in sperm, spermatids, and spermatogonia. Through observation of 322,666 loci in control offspring and 374,026 loci in offspring obtained from 0.64-, 4.75-, or 9.50-Gy-irradiated gametes, specific-locus mutations were phenotypically detected during early development. These putative mutations, designated "total mutation," can be recognized only in embryos of oviparous animals. The developmental fate of these mutant embryos was precisely followed. During subsequent embryonic development, a large fraction died and thus was unavailable for test-crossing, which was used to identify "viable mutations." Our medaka SLT system demonstrates that the vast majority of total mutations is associated with dominant lethal mutations. Thus far only one spontaneous viable mutation has been observed, so that all doubling calculations involving this endpoint carry a large error. With these reservations, however, we conclude that the quantitative data so far obtained from the medaka SLT are quite comparable to those from the mouse SLT and, hence, indicate the validity of the medaka SLT as a possible nonmammalian test system.     

Curative Resection of Microgastrinomas Based on the Intraoperative Secretin Test

The intravenous secretin injection test (secretin test) has been used for the differential diagnosis of gastrinoma. In this study we report that the intraoperative secretin test (IOS test) is also useful for determining the extent of curability in patients with Zollinger-Ellison syndrome (ZES). Twelve patients with ZES underwent surgical exploration and the IOS test. The results of the IOS test were obtained by rapid radioimmunoassay of the serum gastrin level (IRG) within 60 minutes. The test was diagnosed as negative when the maximum increase of serum IRG was less than 80 pg/ml and also less than 20% of the basal serum IRG level. Three of the twelve patients underwent pancreatoduodenectomy (PD), and two patients underwent distal pancreatectomy. Extirpation of duodenal tumors with dissection of regional lymph nodes was performed in seven patients. In two of the seven patients the IOS test remained positive after extirpation of the duodenal tumors and the dissection of regional lymph nodes. In one patient PD was performed on the basis of the positive results, and the IOS test became negative after PD. In the other patient, two tiny metastatic liver tumors were identified and were resected, but the IOS test did not become negative. We closed the abdomen in 11 patients when we obtained negative results from the IOS test. The results of the IOS test were almost identical to the data obtained by the standard assay postoperatively. The serum IRG levels of all but one patient fell to the normal level, and the secretin test became negative postoperatively. The IOS test is thus useful and indispensable for curative resection of microgastrinomas in patients with ZES.     

Roles of human CYP2A6 and 2B6 and rat CYP2C11 and 2B1 in the 10-hydroxylation of (-)-verbenone by liver microsomes.

(-)-Verbenone, a monoterpene bicyclic ketone, is a component of the essential oil from rosemary species such as Rosmarinus officinalis L., Verbena triphylla, and Eucalyptus globulus and is used for an herb tea, a spice, and a perfume. In this study, (-)-verbenone was found to be converted to 10-hydroxyverbenone by rat and human liver microsomal cytochrome p450 (p450) enzymes. The product formation was determined by high-performance liquid chromatography with UV detection at 251 nm. There was a good correlation between activities of coumarin 7-hydroxylation and (-)-verbenone 10-hydroxylation catalyzed by liver microsomes of 16 human samples, indicating that CYP2A6 is a principal enzyme in (-)-verbenone 10-hydroxylation in humans. Human recombinant CYP2A6 and CYP2B6 catalyzed (-)verbenone 10-hydroxylation at Vmax values of 15 and 21 nmol/min/nmol p450 with apparent Km values of 16 and 91 microM, respectively. In contrast, rat CYP2A1 and 2A2 did not catalyze (-)-verbenone 10-hydroxylation at all, suggesting that there were species-related differences in the catalytic properties of human and rat CYP2A enzymes in the metabolism of (-)-verbenone. In the rat, recombinant CYP2C11, CYP2B1, and CYP3A2 catalyzed (-)-verbenone 10-hydroxylation with Vmax and Km ratios (ml/min/nmol p450) of 0.73, 0.20, and 0.03, respectively. Male-specific CYP2C11 was a major enzyme in (-)-verbenone 10-hydroxylation by untreated rat livers, and CYP2B1 catalyzed this reaction in liver microsomes of phenobarbital-treated rats. Rat CYP2C12, a female-specific enzyme, did not catalyze (-)verbenone 10-hydroxylation. These results suggest that human CYP2A6 and rat CYP2C11 are the major catalysts in the metabolism of (-)-verbenone by liver microsomes and that there are species-related differences in human and rat CYP2A enzymes and sex-related differences in male and female rats in the metabolism of (-)-verbenone.     

Gene transfer into rat renal cells using adeno-associated virus vectors

Adeno-associated virus (AAV) vectors have a number of attractive features, including lack of cytotoxicity, ability to transduce nondividing cells, and long-term transgene expression. We investigated whether rat renal cells could be efficiently transduced with AAV vectors. Rat glomerular mesangial cells were transduced with AAV-lacZ vector containing beta-galactosidase gene in vitro, and the expression of beta-galactosidase was evaluated by X-gal staining and ELISA. For ex vivo experiments, sections of rat kidneys were incubated with AAV-lacZ, and then evaluated by X-gal histochemical staining. The level of beta-galactosidase expression in cultured rat mesangial cells increased in a dose-dependent manner (ranging from 1 x 10(5) to 5 x 10(6) particles/cell). When transduced with 5 x 10(6) vector particles/cell of AAV-lacZ, about 50% of mesangial cells were stained positively with X-gal, and the level of beta-galactosidase expression reached 9.9 +/- 1.5 ng/mg protein. Expression was detectable during the culture period for at least 7 days. X-gal histochemical examination of the ex vivo transduced renal tissue revealed tubular cell and interstitial tissue staining. However, gene transfer was not clearly observed in glomeruli. These findings suggest that AAV vectors have the potential for gene therapy of renal diseases.     

The urinary podocyte as a marker for the differential diagnosis of idiopathic focal glomerulosclerosis and minimal-change nephrotic syndrome

BACKGROUND/AIMS: Detection of podocytes in the urine sediment of children indicates that severe podocyte injury occurred in the glomerulus. Focal glomerulosclerosis (FGS) and minimal-change nephrotic syndrome (MCNS) are kidney diseases characterized by massive proteinuria. The aim of the present study was to determine whether urinary podocytes can be detected in patients with idiopathic FGS or MCNS and whether immunosuppression therapy alters these cells. METHODS: Twenty patients with MCNS (nephrotic stage, n = 12; remission stage, n = 8), 15 patients with FGS and 20 healthy controls were included in the present study. Urinary podocytes were stained by immunofluorescence. All patients with MCNS at the nephrotic stage received prednisolone for 6 months, and all patients with FGS received some form of immunosuppression therapy including prednisolone, cyclophosphamide or mizoribine for 12 months. RESULTS: The 12 nephrotic-stage MCNS patients achieved remission after treatment. Seven of the 15 FGS patients also achieved remission, but the other 8 remained in the nephrotic stage. Urinary podocytes were not detected in any patient with MCNS nor were they detected in healthy controls. Urinary podocytes were detected in all FGS patients (mean, 4.2 cells/ml) before treatment and the number of cells decreased in the 7 patients who achieved remission. The number of podocytes was unchanged in the other 8 patients even after treatment. CONCLUSION: Urinary podocytes may be a useful diagnostic indicator for differentiation between FGS and MCNS. These cells may also mark disease progression in cases of FGS.     

Domino liver transplantation from a living related donor

BACKGROUND: Although domino liver transplantations (OLT) from cadaveric donors have been performed in about 50 cases since 1995, only one case in the Japanese literature has been reported on a domino OLT from a living related donor. The difficulties of the later surgery lie in the small size of the graft volume and the short length of the vascular cuffs in the graft. METHODS: The left lobe graft was procured from a 43-year-old younger brother of a familial amyloidotic polyneuropathy (FAP) patient. Next, the left lobe graft (510 g, 44% of the estimated standard liver volume of the FAP patient) was implanted into the 48-year-old female FAP patient. At surgery for the FAP patient, a sufficient length of the vascular cuffs was secured by an extended left lobe resection, although the right lobe graft was able to maintain sufficient vascular cuffs. The right lobe graft (720 g, 54% of the recipient's estimated standard liver volume) was then implanted in the 43-year-old male patient with liver cirrhosis and hepatocellular carcinoma (stage IV-A). RESULTS: The two recipients were discharged from the hospital 1 month after OLT. At 7 months after OLT, they are both doing well and the domino recipient is free of any tumor recurrence. CONCLUSION: A domino OLT from the living related donor can therefore be done safely when careful attention is paid to the graft volume and the length of the vascular cuffs for anastomosis.