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Biomedical subjects

Y Sakai

Publications and source records attributed to Y Sakai.

At least 487 records · Page 27Linked to original sources
PubMed1994

Structure, chromosomal locus, and promoter analysis of the gene encoding the mouse helix-loop-helix factor HES-1. Negative autoregulation through the multiple N box elements.

HES-1 is a mammalian helix-loop-helix factor structurally related to the Drosophila hairy and Enhancer of split proteins. It binds more preferentially to the N box (CACNAG) than to the E box (CANNTG) and acts as a negative regulator. In this study, we have isolated and characterized the mouse HES-1 gene. This gene consists of four exons, and the positions of introns are well conserved when compared with those of the Drosophila hairy gene, except for the third intron. Southern blot and interspecies backcross analyses suggest that the mouse HES-1 gene is a single-copy gene and is located around position 26 on chromosome 16. The transcription initiation site, determined by the S1 nuclease and primer extension experiments, is located 31 nucleotides downstream of a TATA box. In the 5'-regulatory region, there are four N box sequences, and the DNase I foot-printing and gel mobility shift analyses show that HES-1 binds to these sequences. Transient transfection assays using C3H10T1/2 cells suggest that there are several positive regulatory regions in the HES-1 gene. However, cotransfection of the HES-1 expression vector leads to approximately 40-fold repression in promoter activity. Furthermore, when the N box sequences are disrupted, this negative regulation is severely impaired. These results raise the possibility that HES-1 gene expression may be negatively autoregulated through the N box sequences.

Amino Acid Sequence↗
PubMed1994

Noninvasive evaluation of cytochrome c oxidase activity of the liver. Its prognostic value for hepatic resection.

OBJECTIVE: To clarify the relationship between the noninvasive evaluation of hepatic mitochondrial function, the redox tolerance test, and cytochrome c oxidase activity of the liver, focusing on surgical risk in hepatic resection. DESIGN: Six-month randomized clinical trial. SETTING: Inpatients in surgical department. STUDY PARTICIPANTS: Forty patients who underwent hepatic resection (n = 36) and other abdominal operations (n = 4). INTERVENTION: Preoperative, noninvasive: The redox tolerance test, which measures the changes in arterial ketone body ratio in response to 75 g of oral glucose loading. Intraoperative, invasive: Cytochrome c oxidase activity and energy charge of the liver. MAIN OUTCOME MEASURE: Correlation of the index in the redox tolerance test (RTI) with cytochrome c oxidase activity, both of which predict the postoperative course. RESULTS: The RTI values were negatively correlated with the maximal velocity (Vmax) and Michaelis constant (Km) values of cytochrome c oxidase activity. The maximal velocity and Michaelis constant values in patients with RTI values above or equal to 0.5 (group A, n = 29) were significantly lower than those in patients with RTI values below 0.5 (group B, n = 11). Eight (72.7%) of 11 patients in group B experienced postoperative complications. CONCLUSION: The RTI is a noninvasive method of assessing the hepatic energy metabolism and can be a useful index for evaluating surgical risk in hepatectomy.

Adenine Nucleotides↗
PubMed1994

Inhibition by aurintricarboxylic acid of von Willebrand factor binding to platelet GPIb, platelet retention, and thrombus formation in vivo.

Commercial aurintricarboxylic acid (ATA) was separated into molecular-weight (MW) fractions of < 210 to > 25,000, using gel permeation chromatography. Fractions with MW > 1,300 effectively inhibited both botrocetin-induced vWF and bovine vWF binding to fixed human platelets. These activities decreased with a MW > 17,000. Platelet retention for a human in vitro was reduced by ATA at 150 microM, as was that for rats ex vivo at 3 mg/kg. ATA prolonged tail transection bleeding time in rats but had only a weak effect on buccal mucosal bleeding time in dogs. ATA had no effect on platelet count but markedly prolonged PTT. ATA at 10 mg/kg exhibited antithrombotic activity and caused a marked improvement in patency status following successful thrombolysis by t-PA in electrically and copper coil-induced thrombosis models. These results suggest that specific inhibitors of the vWF-GPIb interaction such as ATA may prove useful as antithrombotic agents.

Animals↗
PubMed1994

Host immune suppression after small bowel/liver transplantation in rats.

Simultaneous liver grafting in the Lewis (RT1)-to-DA (RT1) rat strain combination protects small intestinal grafts from rejection. The present study examined host immune responses after combined small bowel/liver transplantation (SBL) in this model. Orthotopic liver transplantation and heterotopic small intestinal transplantation were performed simultaneously and compared with isolated small bowel allografts (SBA) and isolated small bowel isografts (SBI). All rats were sacrificed on postoperative day (POD) 7 or 14 for immunological and histological studies. The mean time to rejection of the SBA was 6.6 +/- 0.3 days. In contrast, there was no clinical or histological evidence of intestinal rejection in SBL recipients during the 14 days of follow-up. The SBL recipients showed clinical and histological evidence of graft-versus-host disease (GVHD). Lymphocyte proliferation and IL-2 production in response to donor antigens were suppressed after SBL transplantation compared with the SBA or the SBI controls (P < 0.05). Cell-mediated cytotoxicity and lymphocytotoxic antibody production against donor cells were also significantly inhibited in the SBL recipients compared with the SBA control group (P < 0.05). We conclude that SBL transplantation in the Lewis-to DA rat strain combination: (1) suppresses host alloimmune responses, (2) prevents early intestinal rejection, and (3) favors the development of GVHD.

Animals↗
PubMed1994

Liver transplantation for Budd-Chiari syndrome: a retrospective study.

A retrospective study was performed on 11 patients who underwent orthotopic liver transplantation for Budd-Chiari syndrome (BCS), 3 of whom had fulminant type BCS and 8, chronic type BCS. Both the 3- and 5-year actuarial survival rates were 64%, after one patient with fulminant, and three with chronic disease died of sepsis or multiple organ failure following transplantation. Anticoagulation therapy in the early postoperative period was tailored to each individual patient. Most of the patients received heparin for several days and were then converted to Coumadin therapy, although some were not given heparin in the immediate postoperative period but were instead commenced on oral Coumadin after the prothrombin time had recovered to within the normal range. All the long-term survivors had received Coumadin therapy and there was no recurrence of BCS and no early thrombotic or hemorrhagic event. One patient developed late thrombosis of the portal vein despite having received apparently adequate Coumadin therapy. It was thus concluded that liver transplantation is an effective therapy for both fulminant and chronic BCS, and that immediate postoperative heparinization is not mandatory for all patients.

Adolescent↗
PubMed1994

Serum gastrin levels following administration of omeprazole alone or in combination with pirenzepine.

Serum gastrin levels in 44 peptic ulcer patients (26 gastric ulcer patients and 18 duodenal ulcer patients) were determined after they had been treated with omeprazole (OPZ) (20 mg/day) alone or in combination with pirenzepine (PZP) (100 mg/day). Serum gastrin levels were measured before, as well as 2, 4, and 6 weeks after administration, and the changes were compared. The levels were significantly elevated (twofold) at 2 weeks of treatment in both the OPZ and OPZ plus PZP groups. In patients taking OPZ alone, the levels rose up to 6 weeks, while in those taking OPZ plus PZP the levels decreased at 4 and 6 weeks. At 4 weeks, serum gastrin levels in the OPZ plus PZP group were lower (although not significantly) than those in patients taking OPZ alone. In gastric ulcer patients, serum gastrin levels in the OPZ group were significantly elevated, while in the OPZ plus PZP group, these levels were only slightly, but not significantly elevated. There was no significant difference between the two gastric ulcer groups at any time. In duodenal ulcer patients, serum gastrin levels increased significantly at 2 weeks of treatment in both groups. At 4 weeks and thereafter, the serum gastrin levels remained significantly high in patients taking OPZ alone, while they decreased at both 4 and 6 weeks in patients taking OPZ plus PZP. Thus, serum gastrin levels in duodenal ulcer patients were markedly decreased by the addition of PZP.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug Therapy, Combination↗
PubMed1994

Carotid body tumor associated with differentiated thyroid carcinoma.

We report a case of a carotid body tumor associated with a primary differentiated thyroid carcinoma. A 44-year-old woman presented with a 10-year history of an asymptomatic mass in her neck. Physical examination revealed a pulsatile submandibular mass in her right neck as well as multiple nodules in the thyroid. Magnetic resonance imaging, computed tomography and, in particular, angiography were diagnostic of the carotid body tumor. Slight changes in serum thyroglobulin levels and thyroid scintigraphy led us to suspect thyroid carcinoma. Embolization of the arteries feeding the carotid body tumor was performed, and was followed by tumor resection 24 h later. At surgery, histopathology confirmed the presence of follicular and papillary carcinomas of the thyroid, resulting in concurrent resection of the gland. There were no residual cranial nerve deficits. The patient subsequently received radiotherapy. Diagnosis and surgical management are discussed, together with pathogenetic factors.

Adult↗
PubMed1994

Vasodilatory capacity of coronary resistance vessels in dilated cardiomyopathy.

Both the endothelium-dependent and endothelium-independent vasodilatory responses of coronary resistance vessels were studied in patients with dilated cardiomyopathy (DCM). A 3F coronary Doppler catheter was placed in the proximal left anterior descending artery in 14 patients with DCM and in 10 patients with chest pain syndrome and a normal heart (control subjects). The ratio of maximum mean coronary blood flow velocity after intracoronary administration of the endothelium-independent vasodilator papaverine (10 mg) to resting mean coronary blood flow velocity (Vp/Vo) in patients with DCM was diminished compared with that in control subjects (2.2 +/- 0.6 vs 4.1 +/- 0.9, p < 0.001). The ratio after administration of the endothelium-dependent vasodilator acetylcholine (40 micrograms) (Va/Vo) in 10 DCM patients was also diminished compared with that in seven control subjects (1.3 +/- 0.5 vs 2.4 +/- 0.8, p < 0.01). In DCM patients, Vp/Vo was correlated with left ventricular end-diastolic pressure (r = -0.48, p < 0.05), left ventricular end-diastolic volume index (r = -0.68, p < 0.01), ejection fraction (r = 0.75, p < 0.01), and left ventricular end-diastolic wall stress (r = -0.73, p < 0.01). However, Va/Vo was not correlated with any of these parameters. These results indicate that impairment of the vasodilatory capacity of coronary resistance vessels in DCM may be related to endothelial dysfunction and to an extravascular factor resulting from left ventricular dysfunction.

Acetylcholine↗
PubMed1994

Contractile hyperreactivity and alteration of PKC activity in gastric fundus smooth muscle of diabetic rats.

Contraction dose dependently induced in gastric smooth muscle of diabetic rats by Bay K 8644 in the presence of 20 mM KCl was about two times that induced in controls, and was inhibited more than 50% by 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7). Contraction was caused in diabetics but usually not in controls by 10(-5) M phorbol 12-myristate 13-acetate (PMA). In diabetics, this contraction was about 2.5 times that in controls. Protein kinase C (PKC) activity in the soluble fraction was depressed by H-7 or staurosporine, and depended on PMA concentration, but was greater in diabetics than in controls at any PMA concentration. PKC activity in the soluble fraction was inhibited by lower Ca2+ concentration, and was greater in diabetics than in controls. Affinity and density of binding sites of a Ca2+ channel antagonist ligand, [3H]PN200-110, were the same in plasma membrane-enriched fractions isolated from either controls or diabetic preparations. Thus, hyperreactivity in diabetic fundus may depend, in part, on alteration of PKC properties, but not on the density of Ca2+ channels.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Effect of trimebutine maleate on the contractile response of the isolated ileum from diabetic rats.

1. Tension of the isolated ileum from diabetic rats induced by streptozotocin was measured isometrically to study the mode of action of trimebutine maleate (TMB). 2. The hyperreactivity of contractile response to KCl was observed in the isolated ileum from diabetic rats. TMB inhibited the contraction induced by KCl and acetylcholine (ACh) in normal solution. 3. In Ca2+ free solution, the hyperreactivity of contractile response to KCl was attenuated, and TMB did not inhibit the contraction induced by KCl. In contrast, TMB inhibited the contraction induced by ACh even in Ca2+ free solution. 4. These results suggest that the hyperreactivity of contractile response to KCl in the ileum from diabetic rats is due to the enhancement of Ca2+ influx through voltage-dependent Ca2+ channel and that TMB inhibits the hyperreactivity of contractile response through the inhibition of Ca2+ movement by the cell.

Animals↗
PubMed1994

High-level ATP production by a genetically-engineered Candida yeast.

Previous studies of ATP production with the methylotrophic yeast, Candida boidinii, suggested that the phosphorylation of AMP catalyzed by adenylate kinase (ADK) was rate-limiting. To investigate whether the enhancement of ADK activity in C. boidinii cells would improve ATP productivity, the Saccharomyces cerevisiae ADK1 gene encoding ADK was expressed in C. boidinii under the C. boidinii AOD1 promoter. Methanol-induced transformants had 10,000-fold enhanced levels of ADK activity and produced 23-fold more ATP from adenosine when compared to the control, parent strain. In a pH-controlled reaction system with successive adenosine-feeding, the ATP concentration in the reaction mixture reached 230 mM (117 g/l) over 45 hours, and was easily purified with an overall yield of 78 percent.

Adenosine Kinase↗
PubMed1994

Self-expanding metal stents for palliative treatment of malignant biliary and duodenal stenoses.

Patients with malignant biliary stenosis due to pancreatic head cancer often have the associated problem of duodenal obstruction. We report here the case of a 78-year-old woman with this clinical situation, who was treated with self-expanding Gianturco metal stents placed in the distal common bile duct and, nine months later, placed in the descending duodenum. The patient's frequent vomiting resolved, and she was able to tolerate peroral solid food; jaundice also decreased (bilirubin pre-stenting: 7.8; post-stenting: 1.2). Self-expanding metal stents therefore appear to be effective for the palliative treatment of malignant duodenal stenosis as well as biliary stenosis.

Aged↗
PubMed1994

In-vitro evidence for the regulation of 17,20-lyase activity by cytochrome b5 in adrenocortical adenomas from patients with Cushing's syndrome.

OBJECTIVE: The electron transfer system molecules, NADPH-cytochrome P450 reductase (Red) and cytochrome b5 (b5) are known to increase the relative activity of 17,20-lyase to 17 alpha-hydroxylase in vitro. Consistent with this hypothesis, we have reported recently that adrenocortical adenomas from patients with Cushing's syndrome that produced exceptionally high concentrations of androgens also contained more b5 mRNA as well as greater 17,20-lyase activity than adenomas that produced low concentrations of androgens. This finding was suggestive but inconclusive in linking b5 functionally to this difference in adenoma 17,20-lyase activity. In the present study, we have extended this finding by examining the effect of b5 on microsomal 17,20-lyase activity using an antibody against cytochrome b5. DESIGN: Biochemical quantitation of the content of b5 and Red activity in the microsomal fraction of the tumours and determination of 17,20-lyase activity in the microsomes in the presence or absence of an antibody against b5. PATIENTS: Seven patients with a clinical diagnosis of Cushing's syndrome secondary to benign adrenocortical adenoma were studied. MEASUREMENTS: The microsomal activities of 17 alpha-hydroxylase, 17,20-lyase and 3 beta-hydroxysteroid dehydrogenase were measured by in-vitro enzyme assay with thin layer chromatography. Microsomal Red activity was assayed by measuring NADPH-dependent cytochrome c reduction reaction. Cytochrome b5 concentration was determined by spectrophotometric analysis. RESULTS: An in-vitro enzyme assay of microsomal fractions from the adenoma showed that the 17,20-lyase activities of two adenomas that produced high concentrations of adrenal androgen were threefold greater than those of five other adenomas that produced low concentrations of androgens. Cytochrome b5 concentrations were greater in the two adenomas with high 17,20-lyase activity than in the other adenomas, while no significant difference in Red activity was observed among all the adenomas. The increased 17,20-lyase activity in the two adenomas was partially but significantly antagonized by an antibody against b5. CONCLUSIONS: These results suggest that differences in tissue b5 are functionally associated with differences in 17,20-lyase activity in adrenocortical adenomas in Cushing's syndrome, resulting in a dissociated secretion of cortisol and androgens in some patients.

Adenoma↗
PubMed1994

A new method, distribution-analyzing latex immunoassay (DALIA), to measure specific immunoglobulin G against mite and wheat allergen in human sera.

A distribution-analyzing latex immunoassay (DALIA), based on the agglutination of latex particles coupled with mite or wheat allergen, was developed to determine allergen-specific IgG in human sera. The immune complex between chemically coupled-allergen latex and specific IgG was agglutinated specifically and efficiently by employing an IgM-type monoclonal second antibody with strong amplification activity. The extent of agglutination was evaluated by determining the relative ratio of volumes (RV) of agglutinates to residual nonagglutinating particles with a particle counter. This method exhibited a high sensitivity (detection limit < or = 5 units/ml) in the determination of allergen-specific IgG, and no influence of inhibitory factors such as competitive antibodies (specific-IgA, -IgM) and nonspecific IgG (< or = 320 mg/ml) was observed. The concentrations of specific IgG against mite allergen in the sera of 130 allergy patients with atopic dermatitis and 52 normal subjects were 22.3 +/- 12.3 and 16.5 +/- 4.2 units/ml, respectively, and the concentrations of specific IgG against wheat allergen in the same two groups were 5.4 +/- 4.2 and 2.1 +/- 2.2 units/ml, respectively. The coefficients of variation of intra- and interassay ranged from 3.4% to 11.2% in both cases. The present method is an excellent homogeneous immunoassay which may be used as a routine assay that can measure 50 samples per hour without prior treatment.

Allergens↗