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Biomedical subjects

M Shimaoka

Publications and source records attributed to M Shimaoka.

At least 37 records · Page 2Linked to original sources
PubMed1999

Resolution of racemic carboxylic acids via the lipase-catalyzed irreversible transesterification of vinyl esters.

The lipase-catalyzed irreversible transesterification procedure using vinyl esters was applied to the resolution of racemic 2-phenoxypropanoic acids. Aspergillus niger lipase showed high enantioselectivities and reasonable reaction rates. The enantioselectivity was found to be affected profoundly by several variables, e.g., the alcohol as nucleophile, the organic solvent used, and the reaction temperature. A gram-scale resolution of (RS)-2-phenoxypropanoic acid was achieved after optimization of the reaction conditions. Then this irreversible transesterification procedure was applied to the resolution of some related 2-substituted carboxylic acids. Thus, racemic 2-methoxy-2-phenylacetic acid was resolved via the A. niger lipase-catalyzed transesterification of the corresponding vinyl ester. 2-Phenylpropanoic acid and 2-phenylbutanoic acid were resolved using Pseudomonas sp. lipase. A gram-scale resolution of 2-phenylbutanoic acid was achieved by this procedure coupled with the porcine liver esterase-catalyzed hydrolysis of the resulting methyl ester.

Carboxylic Acids↗
PubMed1999

Effect of saliva on the growth of Helicobacter pylori.

The effect of saliva mixed in culture media from young healthy volunteers on the growth of Helicobacter pylori (H. pylori) was investigated. Saliva was centrifuged at 15,000 rpm for 10 min and the supernatant was mixed with the reference strain of standard H. pylori which was suspended in sterilized physiological saline. The mixture was inoculated onto agar plate and incubated for 3 days. The numbers of colonies were counted. Saliva from a young male volunteer stimulated the growth of H. pylori significantly compared with the control. This result indicates that there may be such individuals who have saliva increasing the growth of H. pylori. But this is the preliminary report and more studies are needed to know what factors in saliva may affect the growth of H. pylori.

Adult↗
PubMed1998

Molecular characterization of guanosine kinase gene from a facultative alkalophile, Exiguobacterium aurantiacum ATCC 35652.

Guanosine kinase activity was identified in an alkalophile, Exiguobacterium aurantiacum ATCC 35652, and the gsk gene encoding it was isolated as a homologous fragment of the Brevibacterium acetylicum gsk. The cloned chromosomal fragment contained an open reading frame which encodes a polypeptide of 308 amino acids with a molecular mass of 33349 Da. The Ex. aurantiacum Gsk shows strong sequence similarity to B. acetylicum Gsk, but possesses five additional amino acids at the C-terminus. An Mr 39200 protein synthesized in Escherichia coli harboring plasmids carrying Ex. aurantiacum gsk was purified and characterized. A 0.9 kb transcript revealed by Northern blot analysis and the presence of a factor-independent terminator structure suggest that Ex. aurantiacum gsk is monocistronic, although B. acetylicum gsk has been shown to be bicistronic. The striking alterations in the 3'-untranslated region resulted in a different gene organization.

Amino Acid Sequence↗
PubMed1998

A comparative study of physical work load in Japanese and Swedish nursery school teachers.

Comparisons were made of general and local physical work loads between two groups of 58 Japanese and 15 Swedish nursery school teachers. Heart rate, number of steps, rating of perceived exertion (RPE), frequency and time expended with respect to trunk flexion, sitting/kneeling, and lifting/carrying loads of 1 kg or more were monitored during working hours. The average percentage heart rate increase in the maximal heart rate range was lower in the Japanese than in the Swedish teachers. However, all parameters of local physical work load indicating musculoskeletal stress were higher in the Japanese than in the Swedish teachers. The RPE was slightly higher in the Japanese than in the Swedish teachers. These features of general and local work load in the Japanese teachers were typically observed among the teachers in charge of very young children (0-2 years). The Japanese teachers in charge of children aged 3-5 years, on the other hand, had similar levels of both general and local work load as the Swedish teachers in charge of classes comprising children of various ages (1-5 years). The physical work load measured in the present study was not sufficient to explain the difference in the magnitude of musculoskeletal problems for nursery school teachers in the two countries, and other factors should now be examined.

Adult↗
PubMed1998

Orally administered cholera toxin prevents murine intestinal T cells from staphylococcal enterotoxin B-induced anergy.

BACKGROUND & AIMS: Cholera toxin (CT) has been shown to be a strong mucosal adjuvant for the induction of antigen-specific secretory immunoglobulin A (IgA). The mechanism of adjuvant activity of CT is still unknown. The aim of this study was to examine the immunomodulatory function of CT on mucosal T cells using staphylococcal enterotoxin B (SEB) as coadministered oral antigen, because SEB has been shown to directly regulate alpha beta T-cell responses. METHODS: C3H/HeN mice were orally or systemically immunized with SEB and/or CT. The levels of SEB-specific antibodies and frequencies of CD4(+)Vbeta8(+) T cells were analyzed. SEB-specific T-cell proliferation and cytokine production were also determined. RESULTS: Neither SEB-specific IgA nor IgG antibodies were induced in feces when SEB was administered alone. This was a result of the clonal deletion and partial unresponsiveness of CD4(+)Vbeta8(+)T cells in Peyer's patches. On the other hand, SEB-specific antibodies were induced by oral immunization with SEB and CT. Although some degree of clonal deletion was induced by oral immunization with SEB and CT, coadministered CT prevented the induction of anergy for CD4(+)Vbeta8(+) T cells in Peyer's patches. CONCLUSIONS: CT is a powerful immunomodulatory molecule that prevents mucosal T cells from SEB-induced anergy.

Administration, Oral↗
PubMed1998

Up-regulation of Fas ligand (FasL) mRNA expression in peripheral blood mononuclear cells (PBMC) after major surgery.

FasL, which is expressed mainly on activated lymphocytes, can induce apoptosis (programmed cell death) of cells which express Fas. Fas/FasL interaction is primarily beneficial in maintaining immunological and physiological homeostasis by eliminating unnecessary cells. Dysregulation of the interaction, however, leads to tissue damage. We investigated how Fas/FasL levels changed after major surgery. The major aim of this study was to elucidate the involvement of the Fas/FasL system in postoperative inflammation. The investigation involved 10 patients admitted to the intensive care unit after surgery. Although the percentage of Fas+ cells and the amount of Fas expression tended to increase, there was no significant difference between pre- and post-operative samples. In contrast, the levels of FasL mRNA were dramatically up-regulated after operation. Post-operative C-reactive protein (CRP) levels increased and correlated well with FasL levels (r=0.91, P<0.01). Lymphocyte counts decreased after operation and were inversely proportional to FasL levels (r=0.58, P < 0.05). These results suggest that the enhanced FasL expression is likely to be related to systemic inflammatory responses induced during the perioperative period. FasL up-regulation may be involved in the aggravation of tissue damage, including lymphocytopenia, in the early post-operative period.

Aged↗
PubMed1998

Test-retest reliability of isometric and isoinertial testing in symmetric and asymmetric lifting.

The aim of this study was to evaluate test-retest reliability of a dynamometer in measuring lifting strength or force parameters under several combinations of ergonomic factors. Thirteen healthy participants were tested on peak force (PF), related variables and isometric strength (IS) twice, at intervals of 3 months. Correlation coefficients for all parameters in the sagittal plane were 0.60-0.85. Coefficients of variations (CVs) of methodology error for PF in the sagittal plane were 6.2-6.9%. Correlation coefficients and CVs for IS at 90 degrees to the lateral plane were 0.51-0.54 and 16.6-17.9%, respectively. In paired t-tests of the parameters under all conditions, there was a significant difference between test and retest. In the test and retest, ratings of perceived exertions for the low back and the right arm in isometric lifting were significantly higher than those in dynamic lifting. It was concluded that the test-retest reliability of dynamic forces in the dynamometer was high. The peak force in the sagittal plane was considered reliable. In isometric lifting, isometric strength in the sagittal plane seemed reliable, while that at right angles to the lateral plane was considered to be less reliable.

Adult↗
PubMed1998

The influence of surgical stress on T cells: enhancement of early phase lymphocyte activation.

UNLABELLED: For the control of postoperative infection, it may be important to understand the possible influences of surgical stress on the host immune system. To this end, we examined how the early phase of lymphocyte activation was affected in patients after major surgery (eight patients with esophageal carcinoma and six undergoing cardiac surgery) using a flow cytometric assay based on expression of the early activation antigen, CD69. Freshly isolated T cell in preoperative and postoperative samples did not express CD69. When peripheral blood mononuclear cells were stimulated in vitro, the expression of CD69 was greatly enhanced in both CD4 and CD8 T cells, compared with the preoperative samples. The proportion of de novo CD69-expressing cells in the CD4 subset was approximately 3 times (Postoperative Day 1) and 4 times (Postoperative Days 2, 3, 5, and 7) greater than those preoperatively, whereas the proportion of de novo CD69-expressing cells in the CD8 subset was approximately 1.5 times (Postoperative Days 2 and 5) and 2 times (Postoperative Day 3) greater than those preoperatively. The proportion of CD69+ cells was significantly greater in the CD4+ subset than in the CD8+ subset during the postoperative period. IMPLICATIONS: Our results show that major surgical stress enhances the early phase of lymphocyte activation. The augmentation of activation was greater in CD4 (helper) T cells than in CD8 (cytotoxic) T cells.

Aged↗
PubMed1998

Circadian secretion patterns of melatonin after major surgery.

Biorhythms, such as regular variation in core body temperature and the pattern of the secretion of melatonin, are thought to be mediated by the same biological clock. Core body temperature is affected by the inflammatory response to major surgery. Apart from the well-known inhibitory effect of bright light on its secretion, melatonin is an exceedingly good marker of one of the central generating systems of circadian rhythms. We sequentially measured the plasma melatonin concentration pattern in patients who had undergone esophagectomy with thoracotomy to elucidate the circadian rhythm after major surgery. From seven patients who had received esophagectomy with thoracotomy for esophageal cancer, plasma concentrations of melatonin were measured using an RIA method. Blood samples were collected via each patient's arterial line at 00.00, 02.00, 04.00, 06.00, 08.00, 12.00, 16.00, 20.00, and 24.00 hr on the first postoperative day for six of the patients, and, for one patient, every 2 hr until the third postoperative day and every 4 hr thereafter until the sixth postoperative day. Four patients out of seven had melatonin concentrations of over 30 pg/ml (mean 34 pg/ml) at 24.00 hr on the first postoperative day. Five patients showed circadian secretion patterns of melatonin during the first postoperative day. One patient whose melatonin concentrations were measured consecutively for 6 days showed a regular circadian secretion pattern through the 6 days of the study. Even the stress caused by extremely invasive surgery did not significantly disturb the melatonin secretion pattern.

Aged↗
PubMed1998

Epicondylitis among cooks in nursery schools.

OBJECTIVES: To investigate the prevalence and risk factors of epicondylitis among cooks in nursery schools in a cross sectional study because they are suspected to have strenuous workloads on the hands and arms. METHODS: Prevalence of epicondylitis among 209 nursery school cooks and 366 control workers aged 40-59 were studied. Both groups consisted of women workers chosen from 1299 subjects who agreed to participate from 1329 social welfare employees in a city. All workers were interviewed with a questionnaire and had a clinical examination of the tenderness to palpation of epicondyles and epicondylar pain provoked by resisted extension and flexion of the wrist. RESULTS: Nursery school cooks had a significantly higher prevalence of epicondylitis (11.5%) than the controls (2.5%). In a logistic regression model, job title of the cook was also found to have a strong association with epicondylitis (odds ratio (OR) 5.4, 95% confidence interval (95% CI) 2.4 to 11.9) after adjustment for age, body length, and body mass index. Weaker associations were also found between epicondylitis and suspected job stress or workload scores for mechanical workload and psychosocial stressors based on factor analysis. CONCLUSIONS: This study supported the hypothesis that nursery school cooks had a higher prevalence of epicondylitis than other workers with less strenuous hand and arm tasks. It was suggested that risk factors of epicondylitis would be multifactorial, including mechanical workload and psychosocial factors.

Adult↗
PubMed1998

High frequency oscillatory ventilation attenuates the activation of alveolar macrophages and neutrophils in lung injury.

BACKGROUND: Recent investigations have shown that leukocyte activation is involved in the pathogenesis of ventilator-associated lung injury. This study was designed to investigate whether the inflammatory responses and deterioration of oxygenation in ventilator-associated lung injury are attenuated by high-frequency oscillatory ventilation (HFO). We analyzed the effects of HFO compared with conventional mechanical ventilation (CMV) on the activation of pulmonary macrophages and neutrophils in 10 female rabbits. RESULTS: After surfactant depletion, the rabbits were ventilated by CMV or HFO at the same mean airway pressure. Surfactant-depletion followed by 4 h mechanical ventilation hindered pulmonary oxygenation in both groups. Impairment of oxygenation was less severe in the HFO group than in the CMV group. In the HFO group the infiltration of granulocytes into alveolar spaces occurred more readily than in the CMV group. Compared with CMV, HFO resulted in greater attenuation of beta2-integrin expression, not only on granulocytes, but also on macrophages. CONCLUSIONS: In the surfactant-depleted lung, the activation of leukocytes was attenuated by HFO. Reduced inflammatory response correlated with decreased impairment of oxygenation. HFO may reduce lung injury via the attenuation of pulmonary inflammation.

Journal Article↗
PubMed1997

Characterization of guanosine kinase from Brevibacterium acetylicum ATCC 953.

Guanosine kinase (GKase) activity was identified in a cell-free extract of Brevibacterium acetylicum ATCC 953. We have purified the enzyme 4000-fold from the cell-free extract to apparent homogeneity. Molecular weight of 71,300 and 36,300 determined by gel filtration and sodium dodecyl sulfate gel electrophoresis, respectively, revealed that the enzyme is a dimer molecule. Maximum activity of the GKase was attained when the magnesium/ATP concentration ratio was close to 1. The GKase activity was dependent on the presence of a divalent cation. The Km values for guanosine, inosine, and 2'-deoxyguanosine as phosphate acceptors were determined to be 0.022, 0.87, and 2.83 mM, respectively. In addition to ATP and dATP, GTP and dGTP were shown to be effective phosphate donors for the GKase. The optimal pH seemed to be around pH 8.3, although relatively high activity was observed in the alkaline pH range of 7.5-9.8. The addition of 0.1 mM pyrimidine nucleotides, especially CMP and CTP, activated the GKase activity. On the other hand, the addition of 1 mM AMP, ADP, and GMP inhibited the GKase activity. It is thus likely that the GKase activity might be regulated in vivo by nucleotide concentrations and may control the nucleoside monophosphate level by efficiently recycling guanosine.

Adenosine Triphosphate↗
PubMed1997

Bacterial invasion induces interleukin-7 receptor expression in colonic epithelial cell line, T84.

The intestinal epithelial layer forms the interface between the external and the internal environments of a host. Since the interleukin-7 (IL-7) and IL-7 receptor (IL-7R) signaling pathway has been shown to play an important role in the mucosal immune system, we studied the expression of IL-7R in T84, a colonic epithelial cell line, after cells were infected with several types of enteropathogenic bacteria, including Salmonella typhimurium, enteropathogenic Escherichia coli and enteroinvasive Escherichia coli. Bacterial invasion induced IL-7R expression in T84 assessed by a semi-quantitative reverse transcription-polymerase chain reaction technique and flow cytometry. The inhibition of bacterial invasion by cytochalasin D, a specific inhibitor of actin polymerization, led to a reduction in the expression of IL-7R. These data indicate that bacterial invasion into intestinal epithelial cells is likely to be an essential process in the induction of IL-7R. The communication between the epithelium and mucosal lymphocytes which is mediated via IL-7 and IL-7R may be involved in the modulation of the mucosal inflammation which occurs in bacterial infection.

Antigens, CD↗
PubMed1997

Molecular cloning and transcriptional analysis of a guanosine kinase gene of Brevibacterium acetylicum ATCC 953.

The Brevibacterium acetylicum gsk gene, which encodes guanosine kinase (ATP:guanosine 5'-phosphotransferase), a kinase that is involved in guanosine salvage pathways, has been cloned by using the N-terminal amino acid sequence of the purified protein. The cloned chromosomal fragment containing the gsk gene was sequenced and shown to encode a polypeptide of 303 amino acids with a molecular mass of 32,536 Da, which is in good agreement with the measured molecular weight of the purified enzyme. Recombinant Escherichia coli strains harboring plasmids carrying the B. acetylicum gsk gene overexpressed both guanosine and inosine kinase activities. The primary structure of the gsk gene shows similarity to amino acid sequences of sugar kinases classified in the ribokinase family stronger than to those of the E. coli gsk gene encoding guanosine kinase and other nucleoside kinases. Northern blot analysis and primer extension analysis revealed a 1.4-kb transcript and promoter sequences, like the E. coli sigma70 and B. subtilis sigmaA consensus sequences, respectively. These results, together with the nucleotide sequence of the downstream region of gsk, suggested that the organization of B. acetylicum gsk is bicistronic. The second gene, orf2, shows significant similarity to the mutT mutator genes of several organisms, although its function has not yet been identified. The gsk gene was specifically transcribed in the early exponential growth phase, which seems to correspond to the specific guanosine kinase activity profile and suggests a role in controlling the nucleoside monophosphate level by efficiently recycling guanosine when cells are in the early exponential phase.

Amino Acid Sequence↗
PubMed1997

Evaluation of the AMPLICOR CMV test for direct detection of cytomegalovirus in plasma specimens.

We evaluated the AMPLICOR CMV test (PCR) for the direct detection of cytomegalovirus in plasma. Sixty-eight specimens were involved for the comparison between the AMPLICOR test and the antigenemia assay. The sensitivities, specificities, and positive and negative predictive values were 97.1, 100, 100, and 97.1%, respectively, for the AMPLICOR test and 79.4, 100, 100, and 82.9%, respectively, for the antigenemia assay.

Antigens, Viral↗
PubMed1997

Tension pneumopericardium following tracheoplasty for congenital tracheal stenosis.

Tension pneumopericardium is a rare complication of mechanical ventilation following tracheoplasty for congenital tracheal stenosis. This case report describes fatal tension pneumopericardium in a three-month-old male infant some 24 hours following tracheoplasty for this condition. Because of persisting stenosis of the left main bronchus, ventilation pressures of PIP 23 cm H2O and PEEP 5 cm, progressing to PIP 28 cm and PEEP 7 cm were needed to maintain adequate respiratory exchange. Partial relief of the pneumopericardium was achieved by vigorous cardiac massage, but three days later the infant died of massive airway haemorrhage.

Acidosis, Respiratory↗
PubMed1997

Low back pain among cooks in nursery schools.

A cross-sectional questionnaire study was conducted on cooks working for nursery schools in N city in order to verify epidemiological evidence of the work-relatedness of low back pain among them. After female workers aged 30 or more were selected from a study base of 2,799 workers in social welfare facilities, low back pain prevalence of cooks (n = 240) was compared with nursery school teachers (n = 955). Age-standardized prevalence ratios (PRs) of low back pain were 1.9 (95% CI: 1.5-2.5) in cooks compared with nursery school teachers. Among cooks, relative risks of low back pain increased with the increase in the number of lunches to be prepared and decreased with the increase in the number of cooks making lunches in a logistic regression model controlling age and body length. Low back pain was also found to be associated with self-estimated job stressors/ work load by logistic regression models. Multifactorial effects from ergonomic and psychosocial factors, and individual factors on the low back were suggested. From the viewpoint of epidemiological criteria for work-relatedness, it was concluded that the work-relatedness of low back pain among cooks in nursery schools was partially supported.

Adult↗