Biomedical subjects

Y Sakai

Publications and source records attributed to Y Sakai.

At least 19 recordsLinked to original sources

PubMed1992

Inactivation of glibenclamide-sensitive K+ channels in Xenopus oocytes by various calmodulin antagonists.

In follicle-enclosed Xenopus oocytes, extracellular application of cromakalim (a K+ channel opener) or intracellular injection of cAMP induces the smooth outward K+ current which is inactivated by glibenclamide. We found that cromakalim- or cAMP-induced K+ currents in the oocytes were rapidly, reversibly and dose-dependently blocked by various drugs having a calmodulin antagonizing activity in common, namely, by a selective calmodulin antagonist (W-7), antipsychotics (trifluoperazine, chlorpromazine, haloperidol), an antidepressant (amitriptyline), a beta-adrenoceptor blocker (propranolol), a local anesthetic (lidocaine) and a calcium antagonist (prenylamine). W-7, trifluoperazine, chlorpromazine and prenylamine were relatively potent blockers. For example, IC50 values to block cromakalim (100 microM)-induced K+ currents were 12 microM for trifluoperazine and 16 microM for W-7, which were close to their IC50 values to inhibit Ca2+/calmodulin-dependent phosphodiesterase (an index of the potency of calmodulin antagonists). IC50 values to inhibit cAMP (20 pmol/oocyte)-induced K+ currents were 126 microM for prenylamine and 129 microM for chlorpromazine. The IC50 values of all drugs tested to block cromakalim or cAMP responses were significantly correlated with their calmodulin-antagonizing potencies. Isoproterenol-induced K+ currents in the oocytes were also dose-dependently inhibited by glibenclamide, W-7 and trifluoperazine. These results suggest the possibility that the activity of glibenclamide-sensitive K+ channels in follicle-enclosed oocytes are regulated by calmodulin or a calmodulin-dependent process.

Animals↗

PubMed1992

Cloning and sequencing of the alcohol oxidase-encoding gene (AOD1) from the formaldehyde-producing asporogeneous methylotrophic yeast, Candida boidinii S2.

Alcohol oxidase (AOD) is the first key enzyme for methanol metabolism in methylotrophic yeasts. AOD activity is strictly regulated by carbon source. The AOD1 gene was cloned from a gene library of the asporogenous formaldehyde-producing methylotrophic yeast, Candida boidinii S2. The complete nucleotide sequence of the gene and its 5'- and 3'-flanking regions (4174 bp) were determined. To identify the conserved and divergent sequences of the AOD1 gene and its 5'-flanking sequences among different species of methylotrophic yeasts, the AOD-encoding genes from C. boidinii S2 (AOD1), Hansenula polymorpha (MOX) and Pichia pastoris (AOX1 and AOX2) were compared. In addition to conserved amino acid sequences, several DNA segments in the G+C-rich region of 5'-flanking sequences were also found to be conserved. Northern analysis showed that the AOD1 gene transcript was induced by methanol, but was not detected when cells were grown on ethanol or glucose. Thus, as in ascosporogenous methylotrophic yeasts, AOD1 gene expression in C. boidinii appears to be controlled at the RNA level.

Alcohol Oxidoreductases↗

PubMed1992

Molecular cloning, sequence analysis and expression of a cDNA encoding human type-1 angiotensin II receptor.

We isolated a cDNA encoding type-1 angiotensin II receptor from a human liver cDNA library. The cDNA had an open reading frame encoding a protein of 359 amino acid residues with a relative Mr of 41,060. The deduced amino acid sequence of the human angiotensin II (Ang II) receptor was 95.3% and 94.2% identical to those of bovine and rat type-1 Ang II receptors, respectively, and had a significant similarity with the G protein-coupled receptor. The rank order of the binding to the receptor expressed in COS-7 cells was Ang II greater than Ang III greater than Ang I. The expression of the Ang II receptor mRNA was detected in human liver, lung, adrenal and adrenocortical adenomas but not in adrenomedullary tumor, pheochromocytoma, by Northern blot analysis.

Amino Acid Sequence↗

PubMed1992

Hemofiltration as treatment for patients with refractory heart failure.

Hemofiltration was performed in 15 patients with refractory congestive heart failure. All of these patients had oliguria, although intensive treatment with diuretics, digitalis, vasodilators, and catecholamines was prescribed. Hemofiltration was performed under hemodynamic monitoring in 14 patients. The water removal by hemofiltration decreased pulmonary arterial pressure, pulmonary capillary wedge pressure and right atrial pressure. Despite these hemodynamic improvements, nine patients (60%) died within one month after the start of hemofiltration; the causes were fatal arrhythmia in three, renal failure in two, sepsis in one and irreversible cardiogenic shock in three. Oliguria for over 15 h or a serum creatinine concentration of more than 4.0 mg/dl at the start of hemofiltration related to poor prognosis. In view of these results, hemofiltration for refractory heart failure should be started earlier and performed carefully in order to avoid arrhythmia, cardiogenic shock, and other complications.

Adult↗

PubMed1992

Left ventricular diastolic dysfunction in coronary artery disease: effects of coronary revascularization.

Left ventricular diastolic dysfunction was studied globally and regionally in patients with coronary artery disease, and the effects of coronary revascularization were evaluated. A total of 25 patients with angina pectoris who had a stenotic lesion (greater than or equal to 90%) in only left anterior descending branch underwent coronary revascularization [percutaneous transluminal coronary angioplasty (PTCA) in 13 patients and coronary artery bypass graft (CABG) in 12]. Nine patients with normal coronary artery were studied as controls. Left ventricular volume and radial axes were measured on serial frames of one cardiac cycle by cine left ventriculography. The radial axes were drawn from the left ventricular gravity to left ventricular wall at every 20 degrees. Left ventricular filling fraction and distension rate of radial axes were calculated at the times of 25%, 50%, 75%, and 100% of diastolic period, 100% being end-diastole. Although there were no significant changes of the systolic function by revascularization, the filling fraction increased from 11.2 +/- 2.6 to 14.5 +/- 3.5% (p less than 0.001) at 25% time of diastole, from 29.9 +/- 4.9 to 32.5 +/- 5.0% (p less than 0.05) at 50% time in the PTCA group, and from 11.8 +/- 3.7 to 13.4 +/- 3.8% (p less than 0.01) at 25% time in the CABG group. The distension rate of radial axis to the anterior wall also increased significantly at 25% and 50% time of diastole after revascularization, and the change was marked in the PTCA group. However, these increases did not apply to the control patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗

PubMed1992

Surgical technique for combined liver/intestine transplantation in rats.

Simultaneous liver transplantation may reduce the risk of intestinal transplant rejection. We have recently developed two new models of combined liver/intestine transplantation (LIT) in the rat to study this phenomenon. Herein, we report our experience with LIT using a single donor (SD) or multiple donors (MD). Large volumes of fluid were required to prevent a drop in the mean arterial pressure during the anhepatic phase in the SD recipients. Many of the SD recipients died of intraoperative hypovolemic shock (57%). The MD recipients had a shorter anhepatic time (12 +/- 1 minutes vs. 17 +/- 2 minutes; P less than 0.01) and a shorter warm intestinal ischemia time (15 +/- 1 minutes vs. 32 +/- 2 minutes; P less than 0.01). Operative mortality rates were much lower in the MD recipients (10% vs. 68%; P less than 0.01). The long-term survival rate using MD was 71% at 1 month. Graft function was normal in the long-term survivors. LIT with MD provides a good model to study the immunological effects of multivisceral grafting.

Animals↗

PubMed1992

Ocular microangiopathy in familial amyloidotic polyneuropathy, type I.

To obtain precise information on ophthalmological manifestations in patients with familial amyloidotic polyneuropathy (FAP), we performed ophthalmological and histopathological studies on 18 FAP patients and 6 asymptomatic individuals with a mutant transthyretin (TTR) gene. The incidence of vascular abnormalities of the conjunctiva and retina was surprisingly high in FAP patients. Abnormal conjunctival vessels were found mainly in the limbal area of FAP patients, but not in asymptomatic individuals with a mutant TTR gene. Conjunctival biopsy of 5 FAP patients and autopsy of another 2 FAP patients revealed that a significant amyloid deposit could be recognized in the superficial substantia propria of the conjunctiva and wall and perivascular area of the conjunctival vessels in all cases, a finding that is of diagnostic value. As for the retinal vessels, an abnormal arteriovenous ratio (A/V ratio), tortuous retinal vessels, cotton wool exudates and retinal hemorrhages were found in FAP patients. However, histopathological analysis of the retina in two autopsied cases revealed only a trace amount of amyloid deposit around the retinal vessels. Ophthalmological examination of three patients with pandysautonomia revealed that the appearance of both the conjunctival and retinal vessels of these patients was similar to that in FAP patients. These results indicate that in FAP patients ocular microangiopathy may be related to autonomic dysfunction as well as amyloid deposit.

Adolescent↗

PubMed1992

Mapping of the mouse bilirubin UDP-glucuronosyltransferase gene (Gnt-1) to chromosome 1 by restriction fragment length variations.

Restriction endonuclease fragment length variations (RFLVs) were detected by using a rat cDNA probe for the bilirubin UDP-glucuronosyltransferase (UDPGT) gene between two mouse strains, 129/Sv and MOL-MIT. RFLVs of the gene were found by EcoRI and PvuII digestions. From linkage analyses of the three-point cross test using Elo and En-1 as marker genes, the bilirubin UDPGT gene was mapped at position 37 on chromosome 1. Bilirubin and phenol UDPGTs have been suggested to be expressed by a single gene by alternative splicing in human and rat. The mouse bilirubin UDPGT gene was named Gnt-1.

Animals↗

PubMed1992

A molecular genetic linkage map of mouse chromosome 10, including the Myb, S100b, Pah, Sl, and Ifg genes.

Restriction endonuclease fragment length variations (RFLV) on mouse chromosome 10 were detected in four genes, namely, the Myb protooncogene (Myb) and the genes for S100 beta protein (S100b), phenylalanine hydroxylase (Pah), and interferon-gamma (Ifg). RFLV were found in restriction patterns generated with BamHI for Myb, in those generated with BglII for S100b, in those generated with EcoRV for Pah, and in those generated with TaqI for Ifg. A multipoint backcross was carried out by the mating (129/Sv-Sl/+ x MOL-MIT)F1 x 129/SvJ(-)+/+. The Sl mutation has phenotypic effects which include deficiencies in pigment cells, germ cells, and blood cells. The following order of genes was derived from the results of the multipoint backcross, with distances between genes in parentheses: centromere--Myb--(34.9 cM)--S100b--(8.5 cM)--Pah--(8.5 cM)--Sl--(12.3 cM)--Ifg--telomere. Most laboratory strains and two strains of Mus musculus domesticus of wild origin carry the Myba, S100a, Paha, and Ifga alleles. In contrast, a strain of M. m. musculus, two strains of M. m. yamashinai, and two strains of M. m. molossinus carry the Mybb, S100b, Pahb, and Ifgb alleles. Other strains of wild origin carry various combinations of these alleles.

Alleles↗

PubMed1992

Alanine aminotransferase and HCV-RNA responses following interferon therapy of HCV-RNA positive chronic hepatitis.

Interferon (IFN) has been shown to be effective for chronic hepatitis C. This study investigated changes of alanine aminotransferase (ALT) and HCV-RNA in chronic hepatitis C patients treated with alpha-IFN. IFN was given to 73 patients with HCV-RNA positive chronic hepatitis C. The pattern of changes in ALT activity after IFN administration was classified into five types. Type 1 was characterized by normalization of ALT (< or = 25 K.U) during IFN administration and sustained normalization after the IFN therapy. Type 2 involved a rebound of ALT after termination of IFN therapy and subsequent normalization. Type 3 had no ALT normalization during IFN administration, with normalization after the completion of the therapy. Type 4 involved transient normalization of ALT level during IFN therapy, with a subsequent reversion to abnormal levels after the termination of IFN therapy. Type 5 showed sustained abnormally high levels of ALT activity both during and after treatment. Twenty four patients (32.9%) had sustained normalization ALT (< or = 25 K.U) after the termination of IFN treatment. The HCV-RNA negative rate at 6 months after IFN therapy in patients with sustained normalization of ALT was 87.5% (21/24).

Adult↗

PubMed1992

Pancreatic stone predominantly composed of fatty acid calcium.

A 41-year-old man with chronic pancreatitis and pancreatic stones predominantly composed of fatty acid calcium is reported. He had complained of occasional abdominal pain for 10 years and visited the hospital because of a severe attack of abdominal pain. Laboratory data supported a diagnosis of pancreatitis. Computed tomography (CT) showed a high-density area in the head of the pancreas, and the CT number of this high-density area was lower than usual for pancreatic stones. Ultrasonography and endoscopic retrograde pancreatography showed a cystic lesion with small pancreatic stones in the head of the pancreas and irregular dilatation of the main pancreatic duct. Pancreaticojejunostomy and resection of pancreatic cyst were carried out for repeated episodes of abdominal pain under the diagnosis of chronic pancreatitis. The pancreatic stones obtained at surgery were proved to be mainly composed of fatty acid calcium after analysis of chemical composition of the stones. Fatty acid calcium was sometimes found in the biliary stones but never in the pancreatic stones.

Adult↗

PubMed1992

Possible involvement of protein kinase C and calcium in GSH efflux from Hep G2 cells.

We investigated the effects of protein kinase C modulations and calcium mobilization on GSH efflux in Hep G2 cells. GSH efflux from Hep G2 cells was increased by a phorbol ester. Staurosporine, an inhibitor of protein kinase C, diminished phorbol ester-stimulated GSH efflux from the cells. GSH efflux was negatively correlated with extracellular calcium concentrations. Verapamil enhanced GSH efflux, whereas ATP decreased GSH efflux. The latter effect was diminished in the absence of extracellular calcium. Protein kinase C and calcium mobilization may be crucial factors in GSH efflux from human hepatocytes.

Adenosine Triphosphate↗

PubMed1992

Modulating effect of tanshinones on mutagenic activity of Trp-P-1 and benzo[a]pyrene in Salmonella typhimurium.

The modulating effects of the Chinese medicinal plant 'Tan-shen', the radix of Salvia miltiorrhiza Bunge, on the mutagenic activities of Trp-P-1 (3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole) and B(a)P (benzo[a]pyrene) were investigated using Salmonella typhimurium TA98. Ether- and hot water-extracted 'Tan-shen' enhanced both mutagens at low concentrations, but suppressed them at high concentrations. Extracts by ether treatment were more effective than those extracted by hot water. Dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone IIA were isolated from the ether extract by high performance liquid chromatography (HPLC) and were recognized to be the mutagenic modulators. 4 tanshinones enhanced the mutagenicity of Trp-P-1 by 8-24-fold at 20 micrograms/plate and the enhancement was reduced at the higher concentration. Dihydrotanshinone I suppressed Trp-P-1 activity completely at 100 micrograms/plate.

Abietanes↗

PubMed1992

Increase in estrogen receptor levels in MNU-induced thyroid tumors in LE rats.

Estrogen receptor (ER) levels were evaluated in thyroid tumors induced by N-methyl-N-nitrosourea (MNU) and low iodine diet (LID) or propylthiouracil (PTU) in intact and estrogen (E2) loaded Long-Evans (LE) rats. MNU at 40 mg/kg body wt was injected in 50 day-old LE rats of both sexes. The animals were killed 17-22 weeks later and the thyroid tissues were subjected to ER assay. In LID-treated groups, cytosolic ER (cER) levels were 6.7 +/- 5.8 (fmol/mg protein, mean +/- SE) in females and 0.7 +/- 1.4 in males, E2 increased the ER levels. In E2-loaded LID groups, cER levels were 12.9 +/- 3.7 in females and 1.7 +/- 1.7 in males. PTU treatment produced almost comparable ER levels as LID treatment. PTU treatment as well as LID treatment increased the serum TSH levels with E2 treatment producing additional elevation. In evaluating ER levels by histological type of thyroid tumors, the level in cER plus nER showed the lowest value of 6 +/- 6.4 (fmol/mg DNA, mean +/- SE) in hyperplasia, followed by 129 +/- 52.3 in adenoma and 289 +/- 51.7 in carcinoma. The rates of BrdU incorporation in thyroid follicles indicated higher proliferation activity in the area of adenoma and carcinoma rather than in the hyperplastic area. These data suggested that E2 treatment increases the ER levels in MNU and LID/PTU-induced thyroid tumors. The level of ER was correlated to the histological type of thyroid tumors.

Adenoma↗

PubMed1992

Skinfold thickness and cardiovascular risk factors in American and Japanese telephone company executives.

Data from a cross-sectional study of cardiovascular disease risk factors in 962 US and 827 Japanese male telephone company executives were used to determine the associations of skinfold thickness measurements (abdominal, subscapular, triceps, ulnar) with blood pressure, blood glucose, serum cholesterol, and serum triglycerides. These associations were assessed within each group of executives and were compared between the groups. Most skinfolds showed association with risk factors in univariate regression. After adjusting for age and body mass index, the abdominal skinfold continued to be significantly associated with blood pressure and triglycerides in both groups, while the subscapular skinfold showed associations only with triglycerides. After adjustment, the peripheral skinfolds showed no association with risk factors in the US men, however, in the Japanese men the ulnar skinfold continued to be associated with blood pressure. These findings suggest that abdominal and ulnar skinfold measurement may be useful in adjusting for the effect of obesity on coronary heart disease risk in epidemiological studies.

Administrative Personnel↗

PubMed1992

In situ localization of spermatogenic cell-specific glyceraldehyde 3-phosphate dehydrogenase (Gapd-s) messenger ribonucleic acid in mice.

Northern blot analysis with a cDNA clone for mouse spermatogenic cell-specific glyceraldehyde 3-phosphate dehydrogenase (Gapd-s) previously identified transcripts in isolated round spermatids, but not in isolated pachytene spermatocytes, strongly suggesting that Gapd-s transcription first occurs in haploid germ cells. In the present study, in situ hybridization was carried out with a [35S]-labeled anti-sense RNA probe of Gapd-s to define more precisely the temporal expression and spatial distribution of Gapd-s mRNA in adult mouse testes. Gapd-s transcripts were not detected in spermatogonia, primary spermatocytes, secondary spermatocytes, or spermatozoa. However, they were abundant in round spermatids and condensing spermatids. Transcripts were not detected in somatic cells of the testis, in oocytes in pre-antral or antral follicles, or in skeletal muscle. Grain counts were used to define when the Gapd-s gene was expressed during round spermatid development in adult mice. The number of silver grains first exceeded background levels in step 4-6 spermatids (early cap phase of spermiogenesis) and were high in step 7-15 spermatids (acrosome and elongation phases of spermiogenesis). However, they returned to background levels in step 16 spermatids, the final step of spermiogenesis in the mouse. In 20-day-old juvenile mice, Gapd-s transcripts were first detected in round spermatids during the early cap phase of development. These observations confirmed that Gapd-s mRNA is expressed during the post-meiotic phase of male germ cell development, demonstrated that Gapd-s transcripts are present in step 4-15 spermatids, and established that transcription begins in round spermatids during the early cap phase of spermiogenesis in both juvenile and adult mice.

Animals↗

PubMed1992

Establishment of transplantable tumor lines and in vitro cell lines of malignant thymoma developed in a BUF/Mna rat.

A spontaneous malignant thymoma was found in an 18-month-old female BUF/Mna rat and serially transplanted subcutaneously in both syngeneic BUF/Mna rats (designated as MTH-R) and KSN nude mice (MTH-NM) for more than 5 years. Both tumors shared the histological appearance of sarcomatoid carcinoma as seen in the original tumor. However, MTH-NM grew faster than MTH-R in the respective hosts. The MTH-NM grew in both KSN-nude mice and BUF/Mna-rnu/rnu rats but not in BUF/Mna rats, the host of the original tumor. Three continuous tissue culture cell lines (MTHC-1, MTHC-2 and MTHC-3) were established from the MTH-NM tumors at the 2nd, 15th and 17th transplantation generations, respectively. The MTH-NM tumors and latter two tissue culture cell lines carried one or more mouse chromosomes, probably acquired by cell fusion with mouse cells during passages in vivo. The presence of the mouse chromosomes was confirmed by the presence of mouse DNA and of antibodies to the MTHC-2 and MTHC-3 cells in the sera of BUF/Mna rats transplanted with MTH-NM.

Animals↗

PubMed1992

An ubiquitous modulating function of rabbit tracheal epithelium: degradation of tachykinins.

1. To examine the role of epithelium in the responsiveness of tracheal smooth muscle in rabbit, we measured the contractile responses to acetylcholine (ACh), KCl, 5-hydroxytryptamine (5-HT), histamine, substance P (SP), neurokinin A (NKA), and electrical field stimulation EFS) in intact and epithelium-denuded preparations. 2. Removal of epithelium did not alter the contractile response to any agonist examined, except SP. 3. Removal of epithelium enhances the contractile response to SP. In the presence of phosphoramidon, the contractile response to SP was not significantly different in either group. The results suggest that the effect of epithelium is largely due to degradation of SP by enzymes in the epithelium. 4. Arachidonic acid metabolites did not seem to be related to the responses induced by contractile agonists or EFS. 5. In the presence of SP, the contractile responses and [3H]-choline outflow evoked by EFS were dose-dependently enhanced. Contractile responses to EFS and [3H]-choline outflow evoked by EFS were enhanced by SP significantly more than by NKA. Both were abolished by atropine or tetrodotoxin. 6. These results suggest that rabbit tracheal epithelium may modulate SP-induced contractions, both direct and indirect, by inactivation of SP. This phenomenon is widespread in mammals. The rabbit may be a useful model to examine airway cholinergic functions.

Animals↗