Search PubMed⌕ Search

Biomedical subjects

N Shimada

Publications and source records attributed to N Shimada.

At least 19 recordsLinked to original sources
PubMed1992

Isolation and characterization of a gene encoding rat nucleoside diphosphate kinase.

Two overlapping genomic clones for a rat nucleoside diphosphate kinase (NDP kinase) have been isolated and characterized. Complete sequencing of the genomic segment including the whole coding region for the enzyme revealed that the gene consists of four exons spanning 5.5 kilobase pairs. Primer extension analyses and ribonuclease protection assays indicated that the transcription may start from multiple sites with the major initiation site at 3 base pairs upstream from the translation initiation site, Met-1. Neither CAAT-box nor TATA-box could be assigned for each transcription initiation site, whereas five putative Sp1-binding sites (GC-boxes) were present in the 5'-flanking region. These features of the NDP kinase gene represent those of housekeeping genes. In genomic Southern blotting using a full-length rat NDP kinase cDNA as a probe, many positively hybridized fragments were detected. In support of this, five possible processed pseudogenes were identified in different DNA segments although many other NDP kinase-related genomic fragments remained to be characterized. These results demonstrate that the NDP kinase gene may consist of a multiple gene family.

Amino Acid Sequence↗
PubMed1992

Activation of nucleoside diphosphate kinase by mastoparan, a peptide isolated from wasp venom.

We have previously reported that GDP-bound alpha beta gamma-trimeric GTP-binding (G) proteins can be converted into the active GTP-bound form with nucleoside diphosphate (NDP) kinase and ATP, although its exact activation mechanism still remains to be resolved. In the present study, we investigated whether NDP kinase activity was modified by mastoparan, a wasp venom peptide that is known to activate G proteins as an agonist-receptor complex. The activity of NDP kinase measured by the formation of GTP from ATP and GDP was markedly stimulated, when the kinase was incubated with mastoparan. The concentration of mastoparan required for the activation was much lower than that observed for the peptide-induced activation of G proteins under similar assay conditions. There was also an increase in the phosphorylated intermediate of NDP kinase as well as the catalytic activity upon its incubation with mastoparan. These results suggest that mastoparan not only activates G proteins directly via guanine nucleotide exchange reaction but also stimulates NDP kinase activity.

Animals↗
PubMed1992

Flow thresholds for extracellular purine catabolite elevation in cat focal ischemia.

Ischemic glutamate excitotoxicity may be counteracted by adenosine which appears extracellularly during ischemia as an intermediate purine catabolite and has the potential to modulate glutamate release and its receptor action. The present study was conducted to evaluate the flow threshold for purine catabolite accumulation in relation to that for glutamate elevation in focal ischemia which was induced by middle cerebral artery (MCA) occlusion in halothane anesthetized cats. Assemblies of platinum electrodes and microdialysis probes were inserted into the somatosensory (SF, n = 13) and the auditory (A, n = 9) cortices to assess local cerebral blood flow (CBF) using hydrogen clearance and purine catabolite (adenosine, inosine and hypoxanthine) as well as glutamate concentrations in the dialysate using high-performance liquid chromatography (HPLC). In both investigated areas, purine catabolites were elevated if CBF fell below 25 ml/100 g/min, while glutamate increased at a flow threshold below 20 ml/100 g/min. Maximum elevations of adenosine, inosine and hypoxanthine were 76-, 29- and 11-fold, respectively, that of glutamate was 24-fold. In the range between 20 and 25 ml/100 g/min, significant increases of adenosine (5-15-fold) were measured, while glutamate did not markedly increase. The elevation of adenosine was transient whereas that of inosine, hypoxanthine and glutamate persisted over an ischemic period of 3 h. The higher flow threshold for adenosine may reflect an inherent but time limited protective mechanism against glutamate excitotoxicity.

Adenosine Triphosphate↗
PubMed1992

Inhibitory effects of triphosphate derivatives of oxetanocin G and related compounds on eukaryotic and viral DNA polymerases and human immunodeficiency virus reverse transcriptase.

In order to clarify the biological activities of (-)-oxetanocin G, and (-)-oxetanocin A and its carbocyclic analogue, (-)-carboxetanocin G, the inhibitory effects of triphosphate derivatives of these compounds (OXT-GTP, OXT-ATP, and C-OXT-GTP) on eukaryotic and viral DNA polymerases were examined. DNA polymerase alpha purified from calf thymus was weakly inhibited by OXT-GTP and OXT-ATP but strongly by C-OXT-GTP, the Ki value being 0.22 microM. On the other hand, rat DNA polymerase beta was not affected by these analogues. DNA polymerase gamma purified from bovine testes was very weakly inhibited by OXT-GTP and OXT-ATP, but not by C-OXT-GTP. DNA polymerase from herpes simplex virus type-II (HSV-II) was strongly inhibited by all three analogues, the Ki values ranging from 0.5 to 1.0 microM. Human immunodeficiency virus-encoded reverse transcriptase (HIV RT) was also strongly inhibited by these three analogues, the Ki value of C-OXT-GTP being slightly smaller than that of OXT-GTP or OXT-ATP. Analysis of products synthesized on singly primed M13 single-stranded DNA by DNA polymerase alpha, HSV-II DNA polymerase or HIV RT in the presence of the analogues revealed that OXT-GTP and C-OXT-GTP were incorporated into DNA and caused chain termination mainly at sites one or two nucleotides beyond the cytosine bases on the template.

Adenine↗
PubMed1992

Oral health conditions and denture treatment needs in institutionalized elderly people in Japan.

Oral health conditions, including dental conditions, temporomandibular joint (TMJ) conditions, denture status, and oral hygiene status, were assessed on 1908 institutionalized elderly people 65 yr of age and older at 29 of the 30 existing institutions in the city of Kitakyushu, Japan. The percentage of edentulous people was 27% in the 65-74-yr-old group, and increased with age to 56% in the 85 yr and older group. In dentate persons, the mean number of remaining teeth and DF teeth were 13.4 and 8.6, 9.5 and 6.8, and 8.4 and 6.5 in the groups aged 65-74 yr old, 75-84 yr old, and 85 yr and older, respectively. 81% of all the persons examined had no unusual symptoms in their TMJ. A clicking sound was the most frequent symptom (17%). Hygiene of both their teeth and dentures was very poor. Of all the subjects, 36% needed new full and/or partial denture(s), and 41% needed only repair. When the institutionalized elderly people were compared according to their general health condition, no clear differences were observed in percentage of edentulousness, mean number of remaining teeth and DF teeth, and TMJ conditions. However, a higher level of both untreated teeth and denture treatment needs, and poorer oral hygiene, was found in elderly people having poor general health than was observed in those with better health.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

[Quantitative evaluation of stress using the Type A behavior pattern].

The problem of quantitative assessment of individual stress remains to be solved. The purpose of this study was to attempt to quantify the evaluation of stress using the Type A behavior pattern. A total of 1,101 factory workers, 602 male workers (aged 20-59) completed questionnaires regarding subjective symptoms, Type A behaviors, shift work, age, and lifestyles such as drinking habits and smoking habits. Using the results of our previous study, 3 component scores were calculated from the responses to 11 questions pertaining to the Type A behavior pattern. Stepwise logistic regression analysis of complaints of 8 stress-related subjective symptoms was performed, using shift work, age, drinking habits, and smoking habits as categorical independent variables, and 3 component scores as interval-scaled independent variables. The following conclusions were obtained. 1. The first component score, which represented overall irritability, was chosen as an independent variable for complaints of "hunger pains" and "tendency to have diarrhea." The first component score had a positive association with complaints of these stress-related subjective symptoms, and the association with "hunger pains" was statistically significant with P less than 0.05, though the association with "tendency to have diarrhea" was not significant. 2. The second component score, which represented relaxation, was chosen for complaints of "heartburn or gastric reflux" and "abnormal thirst." The second component score had a negative association with complaints of these stress-related subjective symptoms, and both associations were statistically significant with P less than 0.05.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Preclinical and clinical study of FK506 in uveitis.

Efficacy of a new immunosuppressive agent, FK506, in refractory uveitis was studied in 8 patients: 5 with Behcet's disease and 3 with idiopathic retinal vasculitis. The agent was given by oral administration every 12 hours. The previous therapy with systemic corticosteroids or immunosuppressive agents including cyclosporine failed to subside uveitis in these cases. During the observation period of 21.6 +/- 7.8 weeks (mean +/- SD) under FK506 at doses with 0.05, 0.1, 0.15 or 0.2 mg/kg/day, the visual acuity was increased in 44% of treated eyes, unchanged in 44% and decreased in 12%. The inflammatory activity in the ocular fundus was improved in 69% and unchanged in 6% of treated eyes. The effects of FK506 on uveitis by the criteria of improvement of visual acuity and uveitis activity was dose-dependent: 0.05 and 0.1 mg/kg/day were ineffective but 0.15 and 0.2 mg/kg/day were effective in most cases. One patient with Behcet's disease converted from cyclosporine developed moderate renal impairment in 4 weeks under FK506 and the therapy was discontinued in 8 weeks, though the uveitis activity as well as visual acuity was markedly improved. Other 7 cases had no side effect of FK506. Although the number of cases was small and observation period was short, the present clinical data indicate that FK506 is effective to treat refractory uveitis.

Administration, Oral↗
PubMed1992

44-Homooligomycins A and B, new antitumor antibiotics from Streptomyces bottropensis. Producing organism, fermentation, isolation, structure elucidation and biological properties.

Oligomycin antibiotics, 44-homooligomycin A (NK86-0279 II) and B (NK86-0279 I) are newly discovered antitumor antibiotics with the substitution of ethyl for methyl at carbon 26. They were isolated from the culture broth of Streptomyces bottropensis NK86-0279. The structure of these two compounds was deduced by spectroscopic and X-ray crystallographic analyses. These antibiotics showed potent antitumor activities against various tumor cells in vitro, and were active against Colon 26 carcinoma in vivo. Although they showed no activity at 1,000 micrograms/ml against Gram-positive and Gram-negative bacteria and yeast, they have antifungal activity.

Antibiotics, Antineoplastic↗
PubMed1991

Isolation and characterization of bovine haptoglobin from acute phase sera.

A macromolecular hemoglobin-binding protein, which was not detectable in normal bovine sera but appeared during acute phase inflammation, was purified, characterized, and designated as bovine haptoglobin (Hp). The purified protein had a molecular mass of 1,000-2,000 kDa, and was composed of two kinds of peptides, a 20-kDa peptide (alpha chain) and a 35-kDa glycopeptide (beta chain) linked by disulfide bonds. Amino acid composition and N-terminal sequence analyses revealed that both peptides were homologous to each counterpart of human Hp. Studies using some reducing reagents proved that highly polymerized Hp in serum was composed of 2-20 polymerized forms of alpha 2 beta 2 tetramer. Hp could bind one molecule of hemoglobin/alpha 2 beta 2 unit. Hp with smaller sizes obtained from native Hp by partial reduction with cysteine showed almost the same Hb-binding capacity.

Acute-Phase Reaction↗
PubMed1991

Mechanism of inhibition of human cytomegalovirus replication by oxetanocin G.

Oxetanocin G(9-(2-deoxy-2-hydroxymethyl-beta-D-erythro-oxetanosyl)guanine, OXT-G) is a potent and selective agent against human cytomegalovirus (HCMV). In this study we synthesized the triphosphate form of OXT-G, OXT-GTP, and examined its effect on the activities of HCMV DNA polymerase, herpes simplex type 2 (HSV-2) DNA polymerase and human DNA polymerase alpha. OXT-GTP was found to inhibit all these polymerases in a competitive manner with respect to dGTP. The Km for dGTP and the Ki for OXT-GTP of HCMV DNA polymerase were 0.86 and 0.53 mu M, respectively, while the corresponding values of DNA polymerase alpha were 2.2 and 3.6 mu M, respectively. HPLC analysis using [3H]OXT-G also revealed that OXT-G was converted to its triphosphate form 7- to 8-fold more efficiently in HCMV-infected cells than in uninfected cells. The results suggest that both the preferential phosphorylation of OXT-G in HCMV-infected cells and the preferential inhibition of HCMV DNA polymerase by OXT-GTP may contribute towards the selective activity of OXT-G against HCMV replication.

Antiviral Agents↗
PubMed1991

Changes in left ventricular output from fetal to early neonatal life.

Using pulsed Doppler and two-dimensionally directed M-mode echocardiographic techniques, we measured left ventricular (LV) output, stroke volume, heart rate, LV end-diastolic dimension (LVEDD), LV end-systolic dimension, and LV percent fractional shortening (%FS) in 34 normal term infants 12 to 24 hours before parturition and thereafter serially 1, 24, and 96 hours after birth. Stroke volume was calculated as the product of the aortic flow velocity integral and aortic valve area. There was a twofold increase in LV output 1 hour after birth (fetal 170 +/- 46 ml/min/kg vs 1 hour 327 +/- 66 ml/min/kg; p less than 0.01) which was associated with significant increases in stroke volume, %FS, and LVEDD (stroke volume 1.21 +/- 0.33 ml/kg vs 2.25 +/- 0.37 ml/kg; %FS 34.3% +/- 5.8% vs 37.7% +/- 5.4%; LVEDD 15.4 +/- 1.1 mm vs 17.7 +/- 1.4 mm). Heart rate did not change 1 hour after birth. During the subsequent hours after birth, LV output decreased significantly to a value of 245 +/- 56 ml/min/kg (p less than 0.01) at 24 hours, which did not change 96 hours after birth. There were significant declines in stroke volume, LVEDD, and heart rate 24 hours after birth (stroke volume 2.02 +/- 0.42 ml/kg; LVEDD 17.0 +/- 1.1 mm; heart rate 121 +/- 11 beats/min). The %FS remained unchanged within the first 96 hours of age. These results indicate that the major regulator of LV output immediately after birth is stroke volume and not heart rate. The increase in stroke volume is related to an increase in LV size and LV myocardial contractility. Our data provide a useful basis for the interpretation of abnormal LV function in the early neonatal period.

Cardiac Output↗
PubMed1991

Periodontal condition of pregnant women assessed by CPITN.

The periodontal conditions of 2424 pregnant and 1565 non-pregnant women were assessed according to the community periodontal index of treatment needs (CPITN). The aim of this survey was to obtain information which is necessary for the planning of preventive programs of periodontal disease for pregnant women. 95% of the pregnant women and 96% of the non-pregnant women had some signs of periodontal disease. The % of pregnant women having 4 or 5 mm pockets was significantly higher than that of non-pregnant women, increased with the month of pregnancy, reached a maximum of 31% in the 8-month group, but decreased to the control level in the 9-month group. These changes were interpreted to suggest that the increase of pocket depth during pregnancy was caused by gingival enlargement rather than by periodontal destruction. The results show that pregnant women had a healthier periodontal condition when compared with non-pregnant women, i.e., the number of sextants with healthy periodontal tissues was higher, the % of people having deep pockets (6 mm or deeper) was lower, and the need for prophylaxis was lower in pregnant than in non-pregnant women. These findings suggest that a special program of periodontal disease prevention for pregnant women is not necessary.

Adolescent↗
PubMed1991

[Determination of the management level for a body mass index using multivariate analysis].

It is evident that obesity has adverse effects on health and longevity. The body mass index (BMI) is a simple measurement highly correlated with other estimates of fatness and is useful in determining the extent of obesity, but the management level of the BMI for Japanese remains to be evaluated. The purpose of this study is to determine the management level of the BMI for Japanese adjusted for individual life style factors such as smoking and drinking. Among 1,854 male workers in a financial company, those who had periodical health examinations, 1,445 workers (aged 40-58) were chosen. Excluded were those who were below 150 cm or above 180 cm in height or those who had stopped smoking or drinking. Stepwise logistic regression of the findings of 10 medical test items was performed, using age, the BMI, smoking habits, and drinking habits as independent variables. The following conclusions were obtained. 1. The BMI was chosen as independent variable in all medical test items except glutamic oxaloacetic transaminase. In contrast, age and drinking habits were chosen in 6 medical test items, and smoking habits were chosen in 3 medical test items. 2. When the BMI exceeded 24 (kg/m2), significantly higher odds ratios were observed in the following medical test items: total cholesterol, triglyceride, fasting blood glucose and uric acid. Thus, this level of the BMI should be used as the management level in the Japanese male. Taking life styles into consideration, the management level of the BMI seemed to be slightly lower than the ordinary level used in Japan. In order to conduct effective health counseling, this level should be used in health care.

Adult↗