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Biomedical subjects

Y Oka

Publications and source records attributed to Y Oka.

At least 307 records · Page 17Linked to original sources
PubMed1994

Glucose transporter GLUT1 mRNA expression in the ontogeny of glucose incorporation in mouse preimplantation embryos.

Glucose incorporation and utilization in mouse embryos increases during preimplantation development. A reverse transcription-polymerase chain reaction (RT-PCR) was applied to quantitatively determine the levels of glucose transporter GLUT1 mRNA in preimplantation mouse embryos. The levels of GLUT1 mRNA increased during embryonic development, and it was 11-fold greater in blastocysts than in 2-cell embryos. Similar increases were observed in glucose incorporation as measured by 2-deoxyglucose uptake in the embryos. Increases in GLUT1 mRNA and glucose uptake are also observed when 2-cell embryos are developed to blastocysts in vitro, although the levels are one-third to half of those of the in vivo blastocysts. These results suggest that glucose incorporation during preimplantation development depends at least in part on the expression of GLUT1 mRNA transcription, which results in increased amounts of GLUT1 protein and that the difference in its expression in vivo and in vitro may serve as a clue for studying the preimplantation development of embryos.

Animals↗
PubMed1994

Site-specific alteration of arginine 376, the unique positively charged amino acid residue in the mid-membrane-spanning regions of the proline carrier of Escherichia coli.

An alignment of 5 amino acids in the Escherichia coli proline carrier (G328-A366-L371-GR376) is common in the amino acid sequences of several Na+ symport carriers, and it has been proposed as the putative sodium binding motif (Deguchi, Y., Yamato, I., and Anraku, Y. (1990) J. Biol. Chem. 265, 21704-21708). To determine whether these amino acids are essential for Na+ symport activity as the Na+ binding site, one of the amino acids in this alignment, Arg-376, which is the only positively charged amino acid in the innermost part of the predicted membrane-spanning regions, was changed to either lysine, glutamine, or glutamic acid by oligonucleotide dependent site-specific mutagenesis. The transport and binding activities of the proline of the R376K mutant carrier were not detected at all. The activities of the other mutant carriers for uptake and binding of proline were as high as those of the wild-type carrier. These two mutant carriers were as sensitive to the proline analogue azetidine-2-carboxylate and to N-ethylmaleimide as the wild-type carrier, indicating that they have the same properties as the wild-type. The amounts of the carrier proteins expressed from these mutated putP genes were similar to that from the wild-type gene. These results imply that the Arg-376 in the proline carrier does not reside at the sodium binding site, suggesting that the similar alignment found in the amino acid sequences of several Na+ symport carriers is not essential for the transport or binding activities, although this similar alignment may have some relevance to the structure of the Na+ symporter. Furthermore, that the only Arg residue in the middle part of the predicted membrane-spanning regions is dispensable for the energy coupling activity indicates a unique difference of the coupling mechanism from the other secondary active transport systems, such as that of the lactose permease and the tetracycline/H+ antiporter.

Amino Acid Sequence↗
PubMed1994

Overexpression of hexokinase I but not GLUT1 glucose transporter alters concentration dependence of glucose-stimulated insulin secretion in pancreatic beta-cell line MIN6.

The recently established pancreatic beta-cell line MIN6 retains the ability to secrete insulin in response to physiological glucose concentrations. To investigate the role of glucose transport and phosphorylation in glucose-stimulated insulin secretion by beta-cells, MIN6 cells were stably transfected with a rabbit GLUT1 glucose transporter cDNA or a rat hexokinase I cDNA cloned in an expression vector. Overexpression of GLUT1 increased 3-O-methylglucose uptake, but did not alter either glucose utilization or glucose-stimulated insulin secretion. In contrast, clones overexpressing hexokinase I exhibited enhanced glucose-stimulated insulin secretion at glucose concentrations below 10 mM with a concomitant increase in glucose utilization. Maximal insulin secretion as well as the maximal rate of glucose utilization were not altered in these clones. Insulin secretion stimulated by 2-ketoisocaproate, a non-glucose secretagogue, was not affected by hexokinase I expression. These results strongly suggest that the glucose phosphorylating step, but not glucose transport step, regulates glucose-stimulated insulin secretion by modulating the glycolytic rate in the beta-cell.

3-O-Methylglucose↗
PubMed1994

Comparison of the prophylactic usefulness of epirubicin and doxorubicin in the treatment of superficial bladder cancer by intravesical instillation: a multicenter randomized trial. Kobe University Urological Oncology Group.

A multicentric randomized trial was conducted for the purpose of investigating the prophylactic efficacy of intravesical epirubicin instillation following transurethral resection of superficial bladder cancer in comparison with the efficacy of doxorubicin. The patients were centrally randomized into 2 groups and received 19 intravesical instillations of epirubicin or doxorubicin at 30 mg/30 ml physiological saline twice a week for 4 weeks and then once monthly for 11 months. A total of 150 patients with Ta and T1 superficial bladder cancer were entered in the trial, and 114 were evaluable. The nonrecurrence rates determined for each group at 1 and 2 years by the Kaplan-Meier method were 92.8% and 88.6%, respectively, for the epirubicin group and 86.4% and 81.7%, respectively, for the doxorubicin group. The differences between the two groups were not statistically significant. The main side effects encountered in this study were symptoms of bladder irritation such as micturitional pain, pollakisuria, and hematuria. The respective frequencies of those symptoms were 10%, 15.0%, and 5.0% in the epirubicin group and 14.8%, 14.8%, and 0 in the doxorubicin group. These results suggest that epirubicin is a useful drug, comparable with doxorubicin, for intravesical instillation chemotherapy in the prophylactic treatment of superficial bladder cancer.

Administration, Intravesical↗
PubMed1994

Enhanced attachment and elastase-releasing capacity of neutrophils after surgery.

Perioperative changes in neutrophil attachment level and neutrophil elastase-releasing capacity were examined in patients who underwent surgery for either esophageal or gastric cancer. The neutrophil attachment level was significantly increased in both groups to approximately three times that of the preoperative value. The elastase-releasing capacity of nonstimulated neutrophils was not significantly changed, but it was significantly increased in neutrophils stimulated by N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP). Moreover, both neutrophil attachment and elastase-releasing capacity of FMLP-stimulated neutrophils were more enhanced in patients with postoperative complications than in patients without complications. Peak levels of serum interleukin 6, serum alpha 1 proteinase inhibitor, and plasma neutrophil elastase were also significantly higher in patients with postoperative complications than in patients without. These results suggest that during the postoperative period, neutrophils may be primed and activated in response to inflammatory mediators such as cytokines, and that such an alteration of neutrophil functions may reflect the extent of inflammation and may, at times, be implicated in postoperative complications.

Aged↗
PubMed1994

Immunohistochemical double-labeling study of gonadotropin-releasing hormone (GnRH)-immunoreactive cells and oxytocin-immunoreactive cells in the preoptic area of the dwarf gourami, Colisa lalia.

The distribution of gonadotropin-releasing hormone (GnRH)-immunoreactive (ir) cells in the preoptic area (POA) of the dwarf gourami, Colisa lalia, was immunohistochemically studied. These neurons form cell columns on both sides of the common ventricle, and their axons project to the pituitary gland by forming distinct bundles. Also examined was the distribution of isotocin (IST) cells in the POA by using an anti-oxytocin (OXT) serum which has been proven to crossreact with IST. These two kinds of immunoreactive cells were distributed quite similarly in the POA. However, by using an immunofluorescence double-labeling method on thinner sections we found that a population of small IST cells in the ventral POA were also immunoreactive to GnRH, but that large IST cells in the dorsal POA were not immunoreactive to GnRH, and small GnRH-ir cells in the most ventral POA were not immunoreactive to the OXT antiserum. In the pituitary gland, GnRH-ir fibers were found in both the neurohypophysis and proximal pars distalis, but IST fibers were found only in the neurohypophysis.

Animals↗
PubMed1994

NIDDM--genetic marker; glucose transporter, glucokinase, and mitochondria gene.

Candidate genes for NIDDM have been screened in Japanese. Mutations in the glucokinase gene were found in apparent late-onset NIDDM patients as well as in MODY patients. Clinical characteristics in the subjects with glucokinase gene mutations are similar to those in Caucasian subjects; diabetes mellitus is generally mild and some patients actually remain as having impaired glucose tolerance. Of great interest is that all affected subjects show blunted insulin secretion response to the glucose challenge, which is most commonly observed in Japanese NIDDM patients. Thus, it is possible that impairment in the regulation of glucokinase gene expression or its enzyme activity is associated with at least some Japanese NIDDM patients, though the prevalence of the mutations in the coding region is relatively low. In contrast, a mitochondrial tRNA(Leu(UUR)) gene mutation at np 3243 appears to be much more common, and diabetes due to this mutation has a progressive nature. Insulin secretory capacity progressively decreases, eventually reaching an insulin-dependent state in most patients. A surprising result is that this gene mutation is often observed in ICA-positive IDDM patients who were initially non-insulin-dependent, so called slowly progressive IDDM patients. These results suggest that the mitochondrial gene mutation may cause beta cell loss in addition to defects in glucose-induced signaling in pancreatic beta cells, which explains that the mitochondrial gene mutation manifests a wide range of diabetic phenotypes, from NIDDM to IDDM.

Asian People↗
PubMed1994

Cyclic regulation of B220 antigen expression in immature B cell lines.

Three independent immature B cell lines transformed with temperature-sensitive mutants of Abelson murine leukaemia virus (A-MuLV) persistently expressed B220 antigen detected by both of the anti-B220 antibodies RA3-6B2 and 14.8 during culture at the permissive temperature (35 degrees C). RA3-6B2 recognizes the B220 eptiope and that 14.8 is a CD45RA antibody. However, when the culture temperature was shifted up to the non-permissive temperature (39 degrees C) and the culture was continued for 2-3 weeks, a population of the cells (RA3-6B2-14.8+ cells) that lost RA3-6B2 antigen appeared in all three cell lines. From these populations, RA3-6B2-14.8+ subclones were independently isolated by limiting dilution and the phenotype was stable during culture at the permissive temperature. When the culture temperature of the RA3-6B2-14.8+ subclones was shifted up to the non-permissive temperature and the culture was continued for 2-3 weeks, RA3-6B2 antigen was re-expressed in a subpopulation of the RA3-6B2-14.8+ cells. These results demonstrated cyclic regulation of B220 antigen expression during proliferation and/or differentiation of immature B cell lines.

Animals↗
PubMed1994

Pre-B cells adhere to fibronectin via interactions of integrin alpha 5/alpha V with RGDS as well as of integrin alpha 4 with two distinct V region sequences at its different binding sites.

The present study aimed to develop an assay system capable of directly examining the adhesion of cells to each cell-binding site on fibronectin (FN) and to investigate molecular mechanisms underlying the pre-B cell-FN interaction. Treatment of culture plates with 3-(2-pyridyldithio) propionic acid N-hydroxysuccinimide ester and subsequently with dithiothreitol (DTT) allowed the plates to adsorb DTT-treated extracellular matrix (ECM) proteins as well as synthetic peptides containing cysteine at the N-terminal. These treatments produced culture plates coated with ECM proteins or peptides corresponding to its cell-binding sequences, i.e. three sites on FN termed RGDS, LDVP, and RGDV. Pre-B cells exhibited potent adhesiveness to FN-coated plates. Its FN binding was most efficiently inhibited by adding a combination of free forms of RGDS, LDVP, and RGDV peptides, indicating the involvement of these three cell-binding sites in the pre-B cell-FN interaction. In accordance with this, pre-B cells exhibited considerable and potent binding to the respective RGDS-, LDVP-, or RGDV-coated plates. Such binding was specific for the peptide used for coating, because each binding to a given peptide-coated plate was inhibited only by addition of a homologous free peptide. This assay system further demonstrated that the pre-B cell binding to RGDS was mediated by the alpha 5 and alpha v integrins, whereas the binding to LDVP and RGDV was mediated by the alpha 4 integrin. It was also shown that LDVP binding was inhibited by LDVP but not by RGDV and, likewise, RGDV binding was inhibited by RGDV but not by LDVP.2+ interaction involving complex molecular mechanisms.

Amino Acid Sequence↗
PubMed1994

Chronic subdural hematoma associated with middle fossa arachnoid cysts--three case reports.

Three patients with chronic subdural hematoma associated with middle fossa arachnoid cyst were treated by irrigating the hematoma through burr holes, because the symptoms were considered mainly due to increased intracranial pressure caused by the subdural hematoma. The symptoms disappeared immediately afterwards, so no surgery for the middle fossa arachnoid cyst was done. The patients were followed by magnetic resonance imaging. No subdural hematoma recurred during a postoperative period of 11 months to 2.5 years, and the arachnoid cyst reduced in size in two patients. We recommend irrigation of the subdural hematoma as the initial procedure of choice for such cases.

Adolescent↗
PubMed1994

Improvement of therapeutic effect of human recombinant superoxide dismutase on ischemic acute renal failure in the rat via cationization and conjugation with polyethylene glycol.

Therapeutic effect of superoxide dismutase (SOD) and three derivatives: a conjugate with polyethylene glycol (SOD-PEG2), a cationized derivative (cSOD), and a mannosylated derivative (Man-SOD), on acute renal failure induced by ischemia/reperfusion was studied in rats. SOD and derivatives were administered intravenously to the rat after nephrectomy of the right kidney and before and after 60 min occlusion of the left renal artery. At 48 hr after reperfusion, the renal function was evaluated by determining the urinary excretion rate of 14C-inulin injected intravenously. No therapeutic effect on the impaired renal function was shown in the case of low dose SOD (2600 unit/kg) treatment. In contrast, administration of cSOD which was shown to be taken up by the isolated perfused kidney from its capillary side and SOD-PEG2 which maintained high plasma concentration exhibited significant therapeutic effect, as did SOD at ten-fold higher dose (26,000 unit/kg). On the other hand, renal damage was promoted by Man-SOD. Thus, the present study demonstrated that chemical modification may improve the therapeutic effect of SOD on the ischemic acute renal failure and increased SOD concentration in the renal vascular space is an important factor for the improved effect.

Acute Kidney Injury↗
PubMed1994

Superoxide dismutase in developing mouse retina.

Superoxide dismutase (SOD) activity and the production site of H2O2 were studied in the developing mouse retina. The H2O2 production site moved from the inner to the outer region within the outer nuclear layer between the ages of 4 days through 12 days. This shift occurred in parallel with the development of the inner segments of the photoreceptor layer. SOD activity increased significantly at the age of 2-3 weeks. Both manganese-SOD (Mn-SOD) and copper-zinc SOD (Cu,Zn-SOD) activities (combined mean) in the retina of mice older than 2 weeks of age were 1.9 times greater in comparison with those of mice at the age of 2 weeks and younger. The mRNA of Cu,Zn-SOD did not change during these periods, suggesting that the translational efficiency of the mRNA and/or the stability of the SOD enzyme might increase, or the active form of the enzyme might increase during the development of the retina. The results of this study indicate that the localization and production of active oxygen change during the development of the mouse retina, and that SOD activity does exist in the retina from birth, increasing as its role in the protective system against active oxygen increases in the maturing mouse retina.

Animals↗
PubMed1994

Incidental finding of papillary fibroelastoma on the atrial septum.

Papillary fibroelastoma is rare but one of the most common benign primary cardiac tumors after myxoma. This lesion may be associated with embolization, angina and sudden death. The incidental finding of a small pedunculated papillary fibroelastoma arising from the atrial septum detected by transesophageal two-dimensional echocardiography (TEE) in a patient undergoing coronary artery bypass grafting is reported. The advantage of TEE in diagnosing intracardiac tumors is also described.

Coronary Artery Bypass↗