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Biomedical subjects

Y Okada

Publications and source records attributed to Y Okada.

At least 595 records · Page 33Linked to original sources
PubMed1997

Two-sided action of protons on an inward rectifier K+ channel (IRK1).

A cloned inwardly rectifying potassium channel, IRK1, expressed in Xenopus oocytes was found to be sensitive to an extracellular acidic pH level of below 6, achieved by buffering with a membrane-impermeable buffer, phthalate. The voltage dependency of the suppressive effect of pH on the macroscopic current suggested that the location of the proton-sensitive site was at approximately 5% of the distance from the outer entrance to the pore. The single-channel conductance was reduced by protonation of the channel on the extracellular side. The external proton-binding site appears to consist of a single class of negatively charged groups with a pK of around 4.6. An intracellular acidic pH, buffered with membrane-permeable acetate, was found to inhibit, in a voltage-independent manner, the macroscopic IRK1 current with an approximate apparent pK of 5.6 and an approximate apparent Hill coefficient of 2.3. The single-channel activity was abolished by intracellular acidification down to pH 5.0.

Animals↗
PubMed1997

Complement Cls, a classical enzyme with novel functions at the endochondral ossification center: immunohistochemical staining of activated Cls with a neoantigen-specific antibody.

The secondary ossification center of 14- to 16-day-old hamster tibiae was examined immunohistochemically with active and inactive Cls-specific antibodies, RK5 and RK4, respectively. At the ossification center, chondrocytes differentiate from proliferating and hypertrophic to degenerating stages, and their site is occupied by the bone marrow. Cls was strongly immunostained in hypertrophic chondrocytes. In order to discover whether Cls is activated at a particular site, the cartilage was immunostained with RK5 and RK4. RK5 mainly reacted with degrading matrix around invading vessels. In contrast, RK4 strongly stained hypertrophic chondrocytes. Immunoelectron microscopy revealed Cls on degrading fragments of chondrocytes and fibers of cartilage matrix. Decorin, one of the major matrix proteoglycans, was dose and time dependently degraded by Cls. Type II collagen and type I gelatin were also degraded. Articular cartilage from patients with rheumatoid arthritis was positively immunostained (11/12 cases) with an anti-Cls monoclonal antibody (mAb) PG11, whereas normal articular cartilage (5/5 cases) was negative, suggesting Cls participation in the etiology of rheumatoid arthritis.

Amino Acid Sequence↗
PubMed1997

Technical report: coaxial catheter: a new technique for sequential spiral CT during arterial portography and hepatic arteriography.

PURPOSE: To evaluate a coaxial catheter method to sequentially acquire spiral-computed tomography (CT) during arterial portography (CTAP) and hepatic arteriography (CTA) at a single transfer. PATIENTS AND METHODS: Sixteen patients with malignant hepatic tumours (12 patients with hepatocellular carcinoma, four with metastases) were studied using spiral CT. Depending upon the vascular anatomy revealed by conventional coeliac and superior mesenteric arteriography, an outer and inner catheter were selectively placed to perform CTA and CTAP, respectively. CTAP images were obtained first, while injecting contrast material through an inner catheter followed by the acquisition of the CTA images during injection through an outer catheter. In three patients, the resected specimens were available for comparison with the imaging findings. RESULTS: In 12 patients with standard hepatic arterial anatomy, high quality images of CTAP and CTA were obtained. More lesions were detected by the combination of CTAP and CTA than by CTAP or CTA alone in five patients. In one patient with breast carcinoma and a left hepatic artery arising from the left gastric artery, numerous hepatic metastases were delineated on both sets of images. In three patients with replaced or accessory right hepatic arteries, evaluation of the whole liver was difficult on CTA. These procedures were well tolerated by all 16 patients and no complication or technical failure was experienced. CONCLUSION: These preliminary data support this new technique as a promising method of performing CTA and CTAP in patients with standard hepatic arterial anatomy with a single catheter insertion.

Aged↗
PubMed1997

Complications after cyst excision with hepaticoenterostomy for choledochal cysts and their surgical management in children versus adults.

The aim of this study was to review the cases 200 children and 40 adults who had cyst excision combined with hepaticoenterostomy (CEHE) for choledochal cyst, with particular emphasis on post-CEHE complications and their surgical management. Patients who had CEHE at the age of 15 years or less were defined as children, and those aged 16 years or older were defined as adults. The mean age when patients became initially symptomatic was 3 years in children and 26 years in adults. Eleven adults became symptomatic as children (< or = 15 years of age). The mean age of CEHE in children and adults was 4.2 years and 35 years, respectively. The time interval between the onset of initial symptoms and CEHE was significantly less in children than in adults (P < .0001). Of the 200 children, 176 had primary CEHE, and 24 had secondary CEHE converted from cystoenterostomy or other biliary surgery. Seventy children had intraoperative cyst endoscopy, which enabled us to examine the proximal intrahepatic bile ducts for stenosis and debris, and to wash out debris, protein plugs, and stones from the intrapancreatic ducts. Of the 40 adults, 22 had primary CEHE, 18 had secondary CEHE. The mean follow-up period was 10.9 years in children and 10.7 years in adults. The number of patients with post-CEHE complications in children and adults was 18 (9.0%) and 17 (42.5%), respectively. The post-CEHE complication rate in children was significantly lower than in adults (P < .0001). The 18 children had 25 post-CEHE complications such as cholangitis, intrahepatic bile duct stones, pancreatitis, stone formation in the intrapancreatic terminal choledochus or pancreatic duct, and bowel obstruction. Twenty-seven post-CEHE complications developed in the 17 adults including 2 cases of cholangiocarcinoma. There were no post-CEHE complications in the 70 children who had intraoperative cyst endoscopy. No stone formation was seen in the 145 children who had CEHE at the age of 5 years or less. Eight stone formations were seen in seven (12.7%) of the remaining 55 children aged over 5 years. Stones developed in seven (17.5%) adults. The incidence of post-CEHE stone formation in children aged 5 years or less was significantly lower than in other children and adults (P < .0001). Reoperation was required in 15 children: revision of hepaticoenterostomy in 4, percutaneous transhepatic cholangioscopic lithotomy (PTCSL) in 1, excision of intrapancreatic terminal choledochus in 2, endoscopic sphincterotomy of the papilla of Vater in 1, pancreaticojejunostomy in 1, and laparotomy for bowel obstruction in 6. Ten adults required reoperations: revision of hepaticoenterostomy in 2, PTCSL in 2, left hepatic lobectomy in 1, endoscopic sphincterotomy in 2, exploratory laparotomy in 2, and adhesiolysis in 1. The authors conclude that early diagnosis followed by CEHE is the treatment of choice for choledochal cyst, and intraoperative cyst endoscopy is recommended as a valuable adjunct to CEHE.

Adolescent↗
PubMed1997

Association of in vitro growth potential of urinary exfoliated cells with tumor localization and intraluminal recurrence rates of urothelial cancers.

PURPOSE: One problem in the treatment of urothelial cancers, in particular of upper urinary tract cancers, is multifocal synchronous and/or metachronous tumor development in the heterotopic urothelium. We investigated the abilities of exfoliated cells in the urine of patients with urothelial cancers to colonize and proliferate in vitro. MATERIALS AND METHODS: Short-term cultures of 129 urine samples obtained from patients with urothelial cancers and 53 samples from healthy volunteers were compared as to the growth potential of urinary-exfoliated cells and clinico-pathological features, in particular tumor localization and evidence of intraluminal tumor recurrence. RESULTS: Primary cell outgrowth occurred in 112 (86.8%) of the 129 cell cultures from the patients and in 29 (54.7%) of the 53 from the healthy volunteers (p < 0.0001). "Sufficient cell growth" (more than 10(5) cells per flask) was obtained for 77 (59.7%) of the 129 cultures from patients and 7 (13.2%) of the 53 from the healthy volunteers (p < 0.0001). In terms of tumor localization, the rate of sufficient cell growth was significantly higher for patients with upper urinary tract tumor (21/25, 84.0%) than for those with bladder tumor (56/104, 53.8%) (p = 0.0062). Proportional hazard regression analysis showed that only the growth potential of the urinary-exfoliated cells was significantly predictive of intravesical tumor recurrence in patients with superficial bladder tumors (p = 0.011). CONCLUSIONS: The potentials for the colonization and proliferation of urinary-exfoliated cells are associated with intraluminal multifocal tumor recurrence of urothelial cancers.

Adult↗
PubMed1997

Measurement of interleukin-6, interleukin-10, and tumor necrosis factor-alpha levels in tissues and plasma after thermal injury in mice.

BACKGROUND: Cytokines are important modulators of physiologic alterations after thermal injury. Indeed, an increase in the level of circulating cytokines has been documented after thermal injury. However, the mechanism of the increase has not been clarified. We determined cytokine levels in local tissue after thermal injury to identify the tissues responsible for the increase. METHODS: Female C57BL/6 mice each received a 20% full-thickness burn injury. Blood, burned skin, unburned skin, muscle underlying the burn, and muscle of the thigh, liver, spleen, and mesenteric lymph node were sampled at 1, 2, 4, 8, and 24 hours after injury. Uninjured control mice were treated similarly. The samples were cultured, and concentrations of tumor necrosis factor-alpha, interleukin-6 (IL-6), and IL-10 in the culture media were measured by using an enzyme-linked immunosorbent assay. RESULTS: IL-6 levels in unburned skin were significantly increased at 1 hour and decreased at 24 hours, compared with the control. IL-6 levels in muscle underlying the burn were significantly decreased at 8 hours. No elevation of plasma IL-6 levels was observed after injury. Neither tumor necrosis factor-alpha IL-10 was detected in any tissue. CONCLUSIONS: Results indicate that unburned skin may be a major source of IL-6 production after thermal injury and may contribute to the physiologic alterations occurring after such injury.

Animals↗
PubMed1997

Immunohistochemical localization of serotonin, galanin, cholecystokinin, and methionine-enkephalin in adrenal medullary cells of the chicken.

The identification of adrenaline- (A) and noradrenaline- (NA) containing cells in the adrenal medulla of the chicken and colocalization of serotonin and neuropeptides with A or NA in medullary cells were investigated with the use of immunohistochemical methods. Antisera against tyrosine hydroxylase and phenylethanolamine-N-methyltransferase were used as markers for catecholamine- and A-synthesizing cells, respectively. About 70% of catecholamine-synthesizing cells also exhibited immunoreactivity for phenylethanolamine-N-methyltransferase antiserum. Therefore, these cells are A-containing ones and the rest of cells seem to be NA-containing cells. Immunoreactivity with serotonin antiserum was observed in almost all medullary cells. Galanin-immunoreactivity was also found throughout the adrenal medulla, but was stronger in A-containing cells than in NA-containing ones. Cholecystokinin-immunoreactivity was restricted to A-containing cells. Methionine-enkephalin-immunoreactivity was seen in both A- and NA-containing cells, but in about half of medullary cells. From these results, it is suggested that serotonin, galanin, cholecystokinin, and methionine-enkephalin may be co-released with A and/or NA from adrenal medullary cells of the chicken.

Adrenal Medulla↗
PubMed1997

A polypeptide encoded within the murine AIDS defective virus stimulates primary proliferation of CD8+ T-cells.

The murine AIDS (MAIDS) is a retrovirus-induced disease that shows severe immunodeficiency with abnormal lymphoproliferation in susceptible strains of mice. To clarify the antigenicity of gag gene products of the LP-BM5 defective virus, which is known as the causative virus of MAIDS, we expressed and purified the gag p12 gene product (P12) by using a baculovirus expression vector system. The P12 protein strongly stimulated the proliferation of normal C57BL/6 (B6) lymph node T-cells in vitro. Furthermore, a 25-mer synthetic polypeptide within the P12 sequence gave rise to the similar or even higher activation of T-cells. The phenotype of responding T-cells was found to be CD8+ CD44low, indicating that naive CD8+ T-cells respond against a peptide encoded within a MAIDS defective virus gag p12 gene. Finally, the expression of T-cell receptor (TcR) V beta on the responding CD8+ T-cells was analyzed. Although CD8+ T-cells with the particular V beta chains were expanded in response to the 25-mer peptide, this polypeptide does not seem to be a superantigen, since this response is MHC class I-restricted and the V beta preference is not striking. The presentation pathway of this highly antigenic polypeptide will be discussed.

Amino Acid Sequence↗
PubMed1997

Effect of an endothelin-1 antagonist, BQ-485, on cerebral oxygen metabolism after complete global cerebral ischemia in dogs.

Endothelin-1 (ET-1) plays an important role in the physiologic or pathophysiologic regulation of cerebral circulation. To evaluate the effects of the newly synthesized ETA receptor-selective antagonist, BQ-485 (N-perhydroazepin-l-ylcarbonyl-Leu-D-Trp-D-Trp-OH), on the cerebral metabolism of oxygen during the delayed cerebral hypoperfusion that follows global cerebral ischemia, we occluded the ascending aorta and caval veins of 10 beagle dogs for 12.5 min. The animals were randomized into two groups. BQ-485 was given directly into the carotid artery at 0.03 mg/kg per min for 30 min, starting 15 min after reperfusion in the treatment group (n = 5). Isotonic saline was infused in the control group (n = 5). A fiberoptic catheter was inserted into the superior sagittal sinus to monitor its oxygen saturation (SssO2) continuously. Arterial O2 content (CaO2), and sagittal sinus O2 content (CssO2) were monitored before and at 0.5, 1, 2, 4, 6 and 8 h after the ischemic insult. BQ-485 significantly prevented the expected decrease in SssO2 and increase in the cerebral O2 utilization coefficient at 4, 6 and 8 h after the ischemic insult (P < 0.05). Thus, BQ-485 ameliorated the mismatch between O2 supply and demand in the delayed hypoperfusion phase. We conclude that ET may be involved in the pathogenesis of delayed cerebral hypoperfusion after cardiac arrest.

Analysis of Variance↗
PubMed1997

The hemolytic uremic syndrome presenting as bilateral leg ischemia.

The hemolytic uremic syndrome in adults is an uncommon clinical entity consisting of microangiopathic hemolytic anemia, thrombocytopenia, and renal dysfunction. A previously healthy 42-year-old man, after a 2-day prodromal phase, developed severe pain and coldness in both legs, with purpura in the face and extremities. On admission, hepatorenal dysfunction and disseminated intravascular coagulation were evident. These complicated signs and symptoms led to nonspecific supportive therapy because of delayed diagnosis. The patient's condition gradually improved except for ischemia of the legs, which progressed into symmetrical necrosis; eventually, bilateral below-knee amputation was required. This is the first reported case of the hemolytic uremic syndrome complicated by bilateral leg ischemia. A presumed cause of the ischemia was disseminated intravascular coagulation, a rare complication of the hemolytic uremic syndrome.

Adult↗
PubMed1997

KIFC2 is a novel neuron-specific C-terminal type kinesin superfamily motor for dendritic transport of multivesicular body-like organelles.

We have cloned two novel C-terminal motor domain-type kinesin superfamily motor proteins (KIFCs) from mouse brain by utilizing a KIFC-specific consensus sequence. The first protein was the murine homologue of CHO2 antigen, a member of the kar3-type mitotic motor subfamily, and we designated this protein KIFC1. The other protein, KIFC2 (792 amino acids), is novel, with no significant similarity to known kinesin superfamily proteins (KIFs). KIFC2 was specifically expressed in adult neurons, and was immunofluorescently localized to punctate structures in cell bodies and dendrites, but was not detected in axons. Electron microscopic analysis of the immunoisolated KIFC2-bound organelles revealed that KIFC2 associates with multivesicular body (mvb)-like organelles, suggesting that KIFC2 functions as the motor for the transport of mvb-like organelles in dendrites.

Amino Acid Sequence↗
PubMed1997

Postoperative stability after sagittal split ramus osteotomy with condylar-positioning appliance and screw fixation: asymmetric versus symmetric cases.

OBJECTIVE: The purpose of this study was to evaluate postoperative stability in prognathic patients with mandibular asymmetry who were treated with sagittal split ramus osteotomy of the mandible. STUDY DESIGN: Ten asymmetric (group I) and 11 symmetric (group II) patients were examined. An appliance for repositioning the proximal segment was applied, and the bony segments were fixed with titanium screws. Cephalograms were obtained preoperatively, 2 to 3 days postoperatively, and 3 and 6 months after surgery. Changes in the positions of the standard points were examined on lateral cephalograms, and changes in the widths of the gonion points were examined on posteroanterior cephalograms. RESULTS: Statistical analysis revealed no significant difference between the two groups. In addition, there was no significant difference between the postoperative changes in the widths of the gonion points on the deviated and nondeviated sides in group I. CONCLUSIONS: This study suggests that application of an appliance for repositioning the proximal segment can minimize postoperative skeletal changes in patients with asymmetry.

Adolescent↗
PubMed1997

High-resolution HLA-DRB1 and DQB1 genotyping in Japanese patients with testicular germ cell carcinoma.

We report for the first time the frequency distributions of HLA-DRB1 and -DQB1 genes in 55 patients with testicular germ cell carcinoma (TGC) using the modified PCR-RFLP method and compare the results with those for 1216 healthy Japanese control subjects. The modified PCR-RFLP method produced accurate, reproducible cleavage patterns that are easily discriminated. HLA-DRB1*0410 was the susceptibility allele (RR = 3.26, P = 0.006) and DQB1*0602 appears to be a candidate protective allele (RR = 0.26, P = 0.02) for TGC in the Japanese. None of the HLA-DRB1 and -DQB1 alleles showed a specific tendency for histological type or clinical stage of the tumours. Previous studies based on serotyping methods failed to show these allelic associations. High-resolution genotyping is essential because the peptide-binding domain of MHC class II molecules is determined more precisely by their genotypes than by their serotypes. In addition, inherent technical difficulties and typing errors of up to 25% make serotyping inefficient. Our results suggest that high-resolution genotyping is a useful genetic marker to determine risk for TGC.

Female↗
PubMed1997

Transgenic potato expressing a double-stranded RNA-specific ribonuclease is resistant to potato spindle tuber viroid.

We have produced transgenic potato lines expressing the yeast-derived double-stranded RNA-specific ribonuclease pac1. Five lines of pac1 potato (Solanum tuberosum L., cultivar Russet Burbank) challenged with potato spindle tuber viroid (PSTVd) suppressed PSTVd infection and accumulation. All of the progeny potato tubers produced by resistant plants were also free of PSTVd. Because the pac1 gene product digested PSTVd in vitro, double-stranded regions in PSTVd molecule and/or replicative intermediates may be targeted by pac1 gene product in the transgenic potato plant.

Endoribonucleases↗
PubMed1997

Effects of KRN4884, a novel pyridinecarboxamidine type KATP channel opener, on serum triglyceride levels in rats.

1. The effects of KRN4884, a novel pyridinecarboxamidine type KATP channel opener, on serum triglyceride levels were investigated in Sprague-Dawley rats. 2. Oral administration of KRN4884 (3 mg kg-1) for 10 days caused a significant reduction in serum triglyceride levels, which was comparable to that of clofibrate (160 mg kg-1). Reduction in serum triglyceride levels by KRN4884 and clofibrate were accompanied by a reduction in triglyceride levels both in chylomicron and in very low density lipoprotein. KRN4884 treatment did not affect serum concentrations of total cholesterol and phospholipid, but did increase free fatty acid levels. Clofibrate reduced total cholesterol, phospholipid and free fatty acid levels. 3. Administration of clofibrate significantly decreased triglyceride secretion rate as measured by the Triton WR-1339 injection procedure, while KRN4884 did not. 4. Rats receiving KRN4884 exhibited an increase in lipoprotein lipase (LPL) activity both in adipose tissue and in skeletal muscle. There was an inverse correlation between serum triglyceride levels and tissue LPL activities. KRN4884 did not change hepatic triglyceride lipase (HTGL) activity. Clofibrate affected neither LPL nor HTGL activities. 5. It is concluded that administration of KRN4884 results in reduced serum triglyceride levels which may be due to the enhancement of LPL activity in peripheral tissues.

ATP-Binding Cassette Transporters↗
PubMed1997

Multiple thoracic disc herniations: case report and review of the literature.

The incidence of intervertebral disc herniation in the thoracic region of the spine is much less than in the cervical or lumbar areas, and multiple thoracic disc herniations are rare. We described a 33-year-old man with two-level thoracic disc herniation, who exhibited features of spinal cord compression. Magnetic resonance imaging and computed tomographic myelography demonstrated anterior compression of the spinal cord due to disc herniation at T4/5 and T7/8 levels. Through an anterolateral approach, these discs were removed and interbody fusion was performed using autogenous bone grafts. Excellent results were obtained.

Adult↗
PubMed1997

A step-wise expansion of intestinal intraepithelial T lymphocytes in association with microbial colonization is defined by sensitivity to cyclosporin A.

Murine intestinal intraepithelial lymphocytes (IELs) consist of T cells bearing alpha beta-antigen receptor (alpha beta-IELs) and those bearing gamma delta-IELs). Although gamma delta-IELs outnumber alpha beta-IELs in germ-free (GF) mice, oral inoculation of fecal suspension from conventional (CV) mice into GF mice induced the increase in number of alpha beta-IELs, leaving the number of gamma delta-IELs unchanged, and the number of alpha beta-IELs reached the level of CV mice by 3 weeks after conventionalization. Expansion of alpha beta-IELs and increase in their CD44+ subset in conventionalized mice were not affected until 2 weeks after beginning of daily injection of cyclosporin A (CsA). However, further expansion of alpha beta-IELs during 2-3 weeks after conventionalization was blocked by injection of CsA. Although the relative constitution of CD4- 8-, CD4+ 8-, CD4- 8 alpha alpha+, CD4- 8 alpha beta+ and CD4+ 8+ subsets among alpha beta-IELs was comparable between control and CsA-treated groups, CsA injection resulted in the decrease in ratio of high-density fraction cells to low density fraction cells in IELs. CsA completely abrogated the expansion of T cells in peripheral lymph nodes stimulated by alloantigens in vivo, and proliferation of IELs from GF mice induced by immobilized anti-alpha beta-T-cell receptor (TCR) monoclonal antibodies (mAb) in vitro was also eliminated by CsA. These results indicate that microbial colonization-induced expansion of alpha beta-IELs is subdivided into two steps: the early phase of expansion takes place via TCR-non-mediated pathway and the late phase of expansion requires TCR-mediated signal transduction.

Animals↗