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Biomedical subjects

M Okada

Publications and source records attributed to M Okada.

At least 829 records · Page 46Linked to original sources
PubMed1995

A human monoclonal antibody to a human self-antigen, CD2 derived from human peripheral blood lymphocytes engrafted in SCID mice.

To establish human hybridoma lines, production of human immunoglobulin (Ig) and behavior of the implanted human peripheral blood lymphocytes (PBL) were characterized in severe combined immunodeficiency (SCID) mice. Human PBL from healthy donors were injected into the peritoneal cavity of SCID mice, and they were immunized with self-antigen, CD2. CD45+ cells (human PBL) migrated to lymphoid tissues in the mice as early as 4 days, accounting for more than half the lymph node cells and thymocytes. The number of cells releasing human IgG specific to the antigen increased 3.5 weeks after immunization without the usual constraint that production of the IgG, an autoantibody, is prohibited by immunological tolerance in humans. Therefore, we established several human hybridomas secreting human IgG to CD2, since splenocytes and lymph node cells from the implanted SCID mice at 3.5 weeks were fused with a human B lymphoblastoid cell line. A human anti-CD2 monoclonal antibody (MAb) was confirmed to bind to natural CD2 on human T cells by flow cytometric analysis. The epitope for the MAb was identical with a portion that the ligand LFA-3 binded, so that the MAb might reduce the inflammatory reaction caused by preventing activation of human T cells. Here, we report that the human immune system could be reconstituted in SCID mice to develop human hybridomas producing human MAb to a human self-antigen.

Animals↗
PubMed1995

Genomic organization and isoforms of the mouse ELP gene.

Analysis was made on the genomic structure, functions, and expression of the mouse ELP gene, which codes for the embryonal long terminal repeat binding protein. Extensive screening of the cDNA library of embryonal carcinoma cells (EC cells) identified four isoforms of ELP: ELP1 (the original ELP isolate), ELP2, ELP3, and Ad4BP/SF1. Analysis of the genomic sequences revealed that these ELP isoforms were generated by alternative promoter usage and differential splicing. The mRNAs of isoforms initiated at four transcription start sites distributed on three exons. Sequence analysis of the four isoforms identified three polypeptides. The N-terminal portion of ELP1 and ELP2 was longer than ELP3, and Ad4BP/SF1 by 77 aa. The DNA-binding domain and region II were shared by all four isoforms. The C-terminal portion shared by ELP2, ELP3, and Ad4BP/SF1 was 131 aa in length, and that specific to ELP1 was 57 aa in length. The ELP3 and Ad4BP/SF1 isoforms were identical for the coding sequence, but the two differed at the 5' noncoding region. Region II and III domains of nuclear receptors were thought to be involved in ligand-binding and transcriptional activation. ELP1, which lacked region III, functioned as a repressor. The isoforms carrying intact region II and region III functioned as transactivators. Expression of the four isoforms was studied in mouse tissues and in tissue culture cells by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Complex patterns of expression of these isoforms were observed in various tissues. All four ELP isoforms were expressed only in EC cells.

3T3 Cells↗
PubMed1995

Nucleotide sequence of a principal sigma factor gene (hrdB) of Streptomyces griseus.

The hrdB homologue was isolated from a streptomycin-producing Streptomyces griseus 2247 strain, which is independent of A-factor. The nucleotide sequence of the cloned DNA fragment revealed the presence of an open reading frame (ORF) of 1,542bp, which predicted a primary product of 514 amino acids and Mr 56,100. The N-terminal sequence of the purified HrdB protein of S. griseus was identical to the amino acid sequence deduced from the nucleotide sequence. The deduced amino acid sequence contains an "rpoD box" conserved in the principal sigma factors of eubacteria, and shows high similarity to the hrdB products of S. coelicolor A3(2)(89.9%) and S. aureofaciens (88.1%). The cloned gene encodes a principal sigma factor of S. griseus. The promoter region was identified by using a promoter-probe vector and by means of primer extensions experiments. The transcription start point is located 158-bp upstream of the initiation codon.

Amino Acid Sequence↗
PubMed1995

Possible inhibitory effect of lithium on peripheral conversion of thyroxine to triiodothyronine: a prospective study.

The effect of lithium on thyroid function was studied in 18 neuroleptic-treated male chronic schizophrenic in-patients. Lithium carbonate was administered for 8 weeks at a dosage giving a mean serum level of 0.79 mmol/l. Blood was obtained just before and after 8 weeks of lithium administration to determine the serum free thyroxine (free T4) levels, free triiodothyronine (free T3) levels and thyrotropin (TSH) levels. Overall, free T4 and TSH levels significantly increased whereas free T3 levels did not change. Two (11%) patients had abnormally increased free T4 levels and abnormally decreased free T3 levels after 8 weeks of lithium administration. These findings suggest that lithium may inhibit the peripheral conversion of free T4 to free T3 in some susceptible patients.

Adult↗
PubMed1995

Contrasting baroreflex effects of muscimol versus bicuculline injected into the nucleus tractus solitarius in anesthetized rats.

To examine how the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) affects baroreflex regulation, reflex heart rate and renal nerve responses were recorded in anesthetized rats after bilateral injections of muscimol or bicuculline into the nucleus tractus solitarius (NTS). Blood pressure, heart rate, and renal nerve activity were increased by the GABA agonist muscimol and decreased by the GABA antagonist bicuculline. Control injections of the vehicle alone were ineffective. More importantly, all reflex responses later induced by infusing phenylephrine or sodium nitroprusside intravenously were reduced by muscimol. The magnitude of the reflex bradycardia and sympathoinhibition caused by phenylephrine, as well as that of the reflex tachycardia and sympathoexcitation caused by sodium nitroprusside, diminished after NTS injections of muscimol. By contrast, the same reflex responses tended to be enhanced after NTS injections of bicuculline, but most changes were not significant. If GABA acts on receptors located on second-order neurons in the NTS, then muscimol would inhibit those neurons, whereas bicuculline would prevent endogenous GABA from reaching them. Thus muscimol would reduce reflex responsiveness by inhibiting all second-order neurons, whereas bicuculline would enhance it by protecting the same neurons from inhibition by endogenous GABA.

Analysis of Variance↗
PubMed1995

Increased frequency of apolipoprotein epsilon 2 allele in non-insulin dependent diabetic (NIDDM) patients with nephropathy.

The genetic polymorphism of apolipoprotein E (epsilon 2, epsilon 3 and epsilon 4) is associated with lipid abnormalities. It has been suggested that lipid abnormalities may contribute to the development and progression of kidney diseases, including diabetic nephropathy. Thus, in this study we compared the apo E allele frequencies among 146 non-insulin-dependent diabetic (NIDDM) patients with nephropathy, 135 NIDDM patients without nephropathy and 576 of the general Japanese population. The epsilon 2 allele frequency was significantly higher in diabetic patients with nephropathy (7.2%) and with renal failure (9.7%) than in diabetic patients without nephropathy (2.6%) and in the general Japanese population (3.7%). It is concluded that there is a possibility that the epsilon 2 allele is associated with nephropathy in NIDDM.

Alleles↗
PubMed1995

Effects of a selective endothelin A-receptor antagonist, BQ-123, in salt-loaded stroke-prone spontaneously hypertensive rats.

1. We examined the effects of a selective endothelin A (ETA)-receptor antagonist, BQ-123, on the development of hypertension and organ damage in stroke-prone spontaneously hypertensive rats (SHRSP) given 1% NaCl for 6 weeks. 2. BQ-123 at doses of 0.7, 2.1 and 7.1 mg/day was continuously administered for 6 weeks to 8 week old salt-loaded SHRSP, who were given water containing 1% NaCl for the following 6 weeks, via a subcutaneous osmotic minipump. 3. Development of high blood pressure was accelerated in salt-loaded SHRSP compared with that in non-salt-loaded SHRSP. After 6 weeks of salt-loading, incidence of cerebral infarction, renal sclerosis and renal fibrosis were greater in salt-loaded than non-salt-loaded SHRSP. 4. BQ-123 attenuated the age-related rise in blood pressure in a dose-dependent manner. The effect coincided with reduction in the incidence of cerebral infarction and prevention of renal sclerosis and fibrosis. Kidney function was improved as observed by an increase in glomerular filtration rate and decreases in urinary protein excretion, blood urea nitrogen and fractional sodium excretion. Furthermore, BQ-123 prevented increases in the heart weight/bodyweight ratio and aortic wall thickness in salt-loaded SHRSP. 5. These results suggest that endogenous endothelin-1 (ET-1) and ETA-receptors may be, at least in part, involved in the pathogenesis of hypertension and organ damage in salt-loaded SHRSP.

Animals↗
PubMed1995

Dopaminergic system mediation of stimulatory effect of melatonin on secretion of prolactin.

OBJECTIVE: The purpose of the present study was to clarify the mechanism of the stimulatory effect of melatonin on the secretion of prolactin. METHODS: Determination was made of the levels of dopamine (DA), 3,4-dihydroxyphenlacetic acid (DOPAC), serotonin (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) in the median eminence of rats following intravenous melatonin (100 micrograms) administration. RESULTS: Administration of 100 micrograms of melatonin to rats resulted in a significant increase in prolactin secretion (p < 0.01, analysis of variance). Administration of melatonin also resulted in significant decreases in the DOPAC content (p < 0.05) and in the DOPAC/DA ratio (p , 0.05) in the median eminence 1 hour after melatonin administration, at which time serum prolactin was maximal. However, no significant changes were detected in the content of 5-HT or 5-HIAA or in the 5-HIAA/5-HT ratio in the median eminence. CONCLUSION: These results suggest that the stimulatory effect of melatonin on the secretion of prolactin might be mediated by dopaminergic mechanisms.

Animals↗
PubMed1995

Lithium addition to neuroleptic treatment in chronic schizophrenia: a randomized, double-blind, placebo-controlled, cross-over study.

We studied the effect of lithium addition to neuroleptic treatment in chronic schizophrenia, for which contradictory results have been produced in previous studies. Twenty-one chronic schizophrenic inpatients received lithium in a study with randomized, double-blind, placebo-controlled, cross-over design consisting of 8 weeks each of treatment with lithium capsules and identical placebo capsules. The total Brief Psychiatric Rating Scale (BPRS) scores at week 8 of the lithium treatment were improved significantly compared with those at week 8 of the placebo treatment. Of the BPRS subscales, however, only anxiety-depression improved, whereas none of the subscales for anergia, thought disturbance, activation and hostile-suspiciousness improved. There was no significant difference between the total Scale for the Assessment of Negative Symptoms (SANS) scores at any time during lithium and placebo treatment. These results suggest that the addition of lithium to neuroleptic treatment improves anxiety-depression in chronic schizophrenia.

Adult↗
PubMed1995

Recombinant 46-kilodalton surface antigen (P46) of Mycoplasma hyopneumoniae expressed in Escherichia coli can be used for early specific diagnosis of mycoplasmal pneumonia of swine by enzyme-linked immunosorbent assay.

The 46-kDa surface antigen (P46) is the early and species-specific immunogenic protein of Mycoplasma hyopneumoniae. Three TGA codons encoding tryptophan in the P46 gene were replaced with TGG by an in vitro mutagenesis technique. The mutated P46 gene was expressed in Escherichia coli by using the chelating peptide tag system. The purified recombinant P46 was successfully used in an enzyme-linked immunosorbent assay for detection of antibodies against M. hyopneumoniae in swine serum. It did not cross-react with sera from swine infected with Mycoplasma flocculate, Mycoplasma hyorhinis, or Mycoplasma hyosynoviae. With this method, mycoplasmal pneumonia of swine was detectable within 2 weeks after infection.

Amino Acid Sequence↗
PubMed1995

Transvaginal ultrasonographic morphology in polycystic ovarian syndrome.

To assess the morphological findings based on transvaginal ultrasound, the ovarian volume and the number and size of small follicles were studied in 47 patients with polycystic ovarian syndrome (PCOS) diagnosed clinically. Thirty normal volunteers served as controls. The mean ovarian volume (10.3 ml) and number of follicles (10.6) in patients with PCOS were significantly higher than those of controls. An ovarian volume > 6.2 ml and follicles > 10 with a diameter of 2-8 mm were the most prominent features in the ovaries of patients with PCOS and 94% of 47 patients with PCOS had at least one of these ultrasonic findings. However, marked asymmetry of the two ovaries was seen in about 50% of patients with PCOS and a considerable overlap existed between controls and patients with PCOS in the ovarian volume and in the number of follicles. Three (6%) patients with normal ovarian volume and normal number of follicles were observed. Therefore, it is difficult to clearly distinguish a patient with PCOS from a normal woman only by transvaginal ultrasonic criteria using the ovarian volume and/or the number of follicles, although these criteria could be clinically useful for the screening of PCOS.

Adult↗
PubMed1995

Contribution of endothelin-1 to warm ischemia/reperfusion injury of the rat lung.

The purpose of the present study was to clarify the role of endothelin-1 (ET-1) in the pathogenesis of ischemia/reperfusion lung injury and to determine whether pretreatment with an ET receptor antagonist prevents such injury. The left lung of Sprague-Dawley rats was subjected to 60 min of no-flow warm ischemia followed by 90 min of reperfusion. The plasma ET-1 concentration increased significantly after reperfusion compared with before and after ischemia (p < 0.05). Arterial oxygen tension was reduced, and the lung tissue wet/dry weight ratio increased in post-reperfusion lungs compared with both pre-ischemia and post-ischemia lungs. Histologic study showed pulmonary edema, hemorrhage, hyaline membrane formation, and a significant increase in lung tissue neutrophils after reperfusion. In addition, the expression of ET-1 mRNA was determined by Northern blot analysis. Although ischemia did not significantly alter ET-1 expression, reperfusion increased expression in the left lung markedly and in the right lung moderately. Pre-infusion of FR139317, an ETA receptor antagonist, prevented post-reperfusion damage to the lung. These results suggest that ET-1 contributes to the ischemia/reperfusion injury of the rat lung, mediated by an ETA receptor, and that an ETA receptor antagonist may inhibit ischemia/reperfusion lung injury.

Animals↗
PubMed1995

Reduction of left ventricular hypertrophy with St. Jude Medical 19 mm valve prosthesis.

To determine the permissible range of the St. Jude Medical 19 mm valve (SJM19) as an aortic prosthesis, transvalvular maximal pressure gradient (maxPG) and postoperative reduction of left ventricular (LV) hypertrophy were examined in 21 patients (body surface area [BSA] 1.28-1.56 m2, mean 1.42 m2). Doppler echocardiographically measured maxPG at rest was 31 +/- 16 mmHg, which showed no significant difference from the differences in patients' diseases (aortic regurgitation = AR or stenosis = AS), or BSA. The maxPG, also measured during dobutamine administration when they were less than 40 mmHg at rest, increased significantly from 21 +/- 11 mmHg to 32.1 +/- 15 mmHg, having no differences from the differences in diseases or BSA. Reduction of LV hypertrophy was achieved postoperatively (mean postoperative period of ten months), with the reduction rates of 26 +/- 19% in LV mass and 21 +/- 15% in LV cross-sectional area. No significant differences were found between the reduction rates and the differences in the patients' diseases or BSA. These results indicate that, following the implantation of SJM19, LV hypertrophy was reduced in patients with AR as well as with AS, when their BSA values were less than 1.6 m2. However, limited use is recommended because the increase in pressure gradient during exercise cannot be ignored.

Adult↗
PubMed1995

Evoked otoacoustic emissions and electrocochleography in a patient with multiple sclerosis.

A 24-year-old woman with multiple sclerosis had right-sided hearing impairment with tinnitus. She underwent electrocochleography (ECochG) and examination of evoked otoacoustic emissions (EOAEs) to assess cochlear function. An acoustic probe to measure EOAEs was inserted into the external ear canal. The ECochG action potential and cochlear microphonics were recorded by a transtympanic needle electrode technique. Both fast and slow components of EOAEs appeared in either the period of deteriorated hearing acuity or when it was improved. They showed normal detection thresholds and input-output curves during both periods. Cochlear microphonics with almost normal detection thresholds and input-output functions were obtained during the period of deteriorated hearing acuity. Action potential (N1) input-output curves during relapse with hearing loss were notably lower in amplitude and longer in latency than those obtained at the time hearing impairment showed improvement. The EOAE and ECochG findings suggested that this patient had almost normal cochlear function, and we assumed from the magnetic resonance imaging and auditory brain stem response findings as well as the ECochG that the hearing impairment was caused by dysfunction of auditory pathways in the brain stem, including structures that contribute to generation of the N1 potential of the ECochG.

Adult↗
PubMed1995

A new enzymatic method for the determination of inulin.

A new enzymatic method for the determination of inulin in plasma and urine, using inulase (EC 3.2.1.7), fructokinase (EC 2.7.1.4), phosphoglucoisomerase (EC 5.3.1.9) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) is described. The assay is based on the hydrolysis of inulin or Inutest (INutest which is the injectable form of inulin), by inulase and the determination of fructose released. The assay was linear up to 2 g/L of Inutest. The within-batch and between batch coefficients of variation were 2.3% and 2.2%, respectively. Recovery of added Inutest from plasma and urine was 98-102%. There was no interference from glucose (27.7 mmol/L), fructose (1.7 mmol/L) or mannose (1.7 mmol/L). When inulin clearance (using this method) and thiosulphate clearance were compared in 37 patients the inulin clearance was 9.3 mL/min (12%) lower than the thiosulphate clearance. We conclude that this enzymatic method is a simple and specific method.

Anthracenes↗
PubMed1995

Synthesis of 2(1H)-quinolinone derivatives and their inhibitory activity on the release of 12(S)-hydroxyeicosatetraenoic acid (12-HETE) from platelets.

A search for potent inhibitors of release of 12(S)-hydroxyeicosatetraenoic acid (12-HETE), which plays an important role in the pathogenesis of various circulatory disorders and arteriosclerosis, led us to 6-[4-(1-cyclohexyl-5-tetrazolyl)butoxy]-3,4-dihydro-2(1H)-quinolinone (cilostazol) and 2(1H)-quinolinone derivatives having an azole group in the side chain. Many 2(1H)-quinolinone derivatives were synthesized and tested in vitro for the inhibitory activity in human platelets. 3,4-Dihydro-6-[3-(1-o-tolylimidazol-2-yl)sulfinylpropoxy]-2( 1H)-quinolinone (5k) was found to be one of the most potent inhibitors of 12-HETE release, being more potent than esculetin. In addition, the sulfoxide 5k showed in vivo inhibitory activity on platelet adhesion in rats. Since 5k is racemic, the enantiomers were prepared and their potencies were compared in vitro and in vivo. (S)-(+)-5k had the best pharmacological profile and was selected as a candidate drug for further development. The structure-activity relationships are discussed.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗