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Biomedical subjects

Y Tahara

Publications and source records attributed to Y Tahara.

At least 55 records · Page 3Linked to original sources
PubMed1995

In vitro antibacterial activity of FA103, a new quinolone derivative of C-7 position with 7-perhydrodiazepinone.

A number of new quinolone antibacterial agents such as ofloxacin, norfloxacin, ciprofloxacin and sparfloxacin have been developed and introduced to the market. They possess a broad spectrum of activity against Gram-positive and Gram-negative bacteria. Ciprofloxacin has the highest activity against Gram-positive is higher than other quinolones. The activity of these quinolones against Gram-negative bacteria is generally higher than against Gram-positive bacteria. The substitution group of quinolones at C-7 position is responsible to show similar antibacterial activity with broad spectrum and similar pharmacokinetic properties, and variety of the substituents have been synthesized in many laboratories. Most of the substituents are piperazinyl of six-membered ring or pyrrolidinyl of five-membered ring, being modified with an alkyl group or another group. The development of potent quinolones against bacteria involved in pneumonia was seemed to be useful, and we investigated structure-activity relationships of new quinolones with a stronger activity against Gram-positive bacteria. A quinolone derivative with a seven-membered ring, perhydrodiazepinone, at the C-7 position was found to be a candidate for further evaluation. No previous attempts have been made to synthesize this type of derivatives. The compound FA103, 5-amino-1-cyclopropyl-6,8-difluoro-7-(2,3,4,5,6,7-hexahydro-1 H-1,4-diazepin-5-on-1-yl)-1,4-dihydro-4-oxoquinoline-3-carboxylic acid, was synthesized and evaluated. Chemical structure of FA103 is shown in Fig. 1. This is a new difluoroquinolone with a broad antibacterial spectrum and improved activity against Gram-positive bacteria. In this paper, we compare the in vitro activity of FA103 with that of ofloxacin, norfloxacin, sparfloxacin against Gram-positive and Gram-negative bacteria.

Anti-Infective Agents↗
PubMed1995

[Hydrostatic weighing, skinfold thickness, body mass index relationships in high school girls].

A study was conducted to evaluate body composition by hydrostatic weighing, skinfold thickness, and body mass index (BMI) in 102 senior high school girls, aged 15 to 18 in Nagasaki City. Body density measured by the underwater weighing method, was used to determine the fat weight (Fat) and lean body mass (LBM. or fat free weight: FFW) utilizing the formulas by Brozek et al. The results were as follows; 1. Mean values of body density were 1.04428 in the first grade girls, 1.04182 in the second grade, and 1.04185 in the third grade. 2. Mean values of percentage body fat (%Fat) were 23.5% in the first grade, 24.5% in the second and 24.5% in the third. 3. Percentage body fat (%Fat), lean body mass (LBM) and LBM/Height were not significantly with different advance of grade from the first to the third. 4. The correlation coefficients between percent body fat and the sum of two skinfold thicknesses, the sum of three skinfold thicknesses and the sum of seven skinfold thicknesses was 0.78, 0.79, and 0.80 respectively and were all statistically significant (p < 0.001). 5. The correlation coefficients between BMI and the sum of two skinfold thicknesses, the sum of three skinfold thicknesses and the sum of seven skinfold thicknesses was 0.74, 0.74, and 0.74 respectively and were all statistically significant (p < 0.001). 6. Mean values of BMI, Rohrer index and waist-hip ratio (WHR) in all subjects (n = 102) were 20.3, 128.2 and 0.72 respectively.

Adolescent↗
PubMed1994

Glyburide enhances insulin gene expression and glucose-induced insulin release in isolated rat islets.

Long-term glyburide therapy has been reported to improve glucose-induced insulin secretion in patients with NIDDM. We examined the effects of glyburide on the synthesis and release of insulin and insulin gene expression in isolated islets in vitro. Incubation with glyburide (500 ng/ml) significantly increased insulin release without affecting the insulin content. The PPI mRNA level was not increased after incubation for 1 h but was increased after incubation for 20 h. Incubation with 5 ng/ml of glyburide for 1 h or 20 h had no effect on the content or release of insulin, but incubation with 5 ng/ml of glyburide for 20 h significantly increased the PPI mRNA level and enhanced insulin release induced by 11 mM glucose. These results suggest that a high concentration of glyburide stimulates insulin release directly, while a low concentration of glyburide increases the PPI mRNA level and may thereby enhance glucose-induced insulin release.

Animals↗
PubMed1994

A new method to measure bilayer thickness: cryo-electron microscopy of frozen hydrated liposomes and image simulation.

A new method to measure the bilayer thickness of liposomes is described. Frozen hydrated liposomes composed of either phosphatidylcholine (PC) or PC containing 30 mol% cholesterol were observed in vitreous ice with a cryo-electron microscope, which enables high-resolution observation of frozen-hydrated unstained biological specimens. The examined PCs were di-(saturated acyl) PCs (di-C12:0 (DL), diC14:0 (DM), di-C16:0 (DP)), unsaturated acyl PCs (diC18:1 (DO), C16:0-C18:1 (PO)) and PC from a natural source (egg-yolk (EY) PC). Every liposome image displayed a pair of concentric circles indicating a different bilayer structure due to the acyl-chain species. The observation of the liposomes showed the following results; (1) liposomes including unsaturated acyl PC (DOPC, POPC and EYPC) displayed a smooth and regular image of the bilayer and sharp distributions of the bilayer thickness, while the images of those composed of di-(saturated acyl) PC (DLPC, DMPC and DPPC) showed irregular shapes and wide distributions of the bilayer thickness, (2) addition of 30 mol% cholesterol to the di-(saturated acyl) PCs dispelled the irregularity in the shape of the membrane and the distribution of the bilayer thickness, and (3) the mean bilayer thickness of the liposome composed of di-(saturated acyl) PCs increased corresponding to the carbon numbers of the acyl chains. The reliability of the observations and measurements was confirmed by coupling of the cryo-electron microscopy with image simulation using the MULTI SLICE computer program and the error estimation of +/- 0.63 A using images of crystalline chlorinated copper phthalocyanine.

Computer Simulation↗
PubMed1994

Gestational age assessment in Japanese low birthweight infants.

We evaluated the validity of the Ballard scoring system for assessing gestational age in Japanese low birthweight infants. Infants included in this study were 116 neonates who were admitted to seven hospitals in Hokkaido. Gestational ages of all infants were prenatally established by ultrasonographic measurement of the crown-rump length performed between 8 and 12 weeks of gestation (clinical age). Of these, 74 infants were appropriate for gestational age (AGA) and the remaining were small for gestational age (SGA). Mean birthweight was 1703 g and 34% (39/116) were < 1500 g. The correlation coefficient for the total population was 0.93 (P < 0.001). Although mean Ballard age tended to overestimate clinical age, mean differences between Ballard age and clinical age did not exceed 0.6 weeks. Agreement within 2 weeks among all infants was 86.2%. Percentages of agreement within 2 weeks did not differ to a statistically significant degree between AGA and SGA. These results indicate that the Ballard method is of value in assessing gestational age in Japanese low birthweight infants.

Evaluation Studies as Topic↗
PubMed1994

[Sex differences in interrelationships between percent body fat (%fat) and waist-to-hip ratio (WHR) in healthy male and female adults].

The purpose of the present study was to investigate sexual differences in relationships among percent body fat (%Fat), waist-to-hip ratio (WHR), waist-to-stature ratio (WSR), abdominal circumference to stature ratio (ASR), body mass index (BMI) and skinfold thicknesses in healthy male and female adults. Subjects were 64 males and 65 females, aged 22-60. Body density was measured by under water weighing and by skinfold anthropometry. Mean %Fat was 15.6% in males and 23.9% in females. Mean WHR was 0.83 in males and 0.72 in females. The correlation between %Fat and WHR was not significant in females (r = -0.104) but was significant in males (r = 0.631, p < 0.001). Highly significant correlations were obtained among %Fat, WSR, ASR, BMI, and sum of eight skinfolds in both sexes.

Adipose Tissue↗
PubMed1994

Classification of body shape of male athletes by factor analysis.

The purpose of this study was to evaluate the body shape of athletes in comparison with adult non-athletes by factor analysis. The subjects were 210 male adult non-athletes and 485 male high school age and adult athletes participating in 13 different sporting events. Physique, skinfold thickness and body composition of each subject were measured. Measured values from adult non-athletes were analyzed by factor analysis, and body shape of the athletes was then analyzed according to these factors. The results are summarized as follows: 1. Four main factors, that is, body fat, mass, leg length to height ratio and length, which could explain 88.5 percent of total variance, were extracted from the measured values from adult non-athletes. 2. Similarity of body shape between sporting events was analyzed by cluster analysis. Body shape of the athletes could be classified into 3 categories: muscular and well-balanced type; rich muscular and large-built type; and rich muscular and long-torso type. Compared with adult non-athletes, male athletes had less body fat and greater mass except for long-distance runners. The present results suggested that the athletes had body shapes suitable to their sporting events.

Adult↗
PubMed1993

Cellular mechanism of glyburide-induced insulin gene expression in isolated rat islets.

The cellular mechanism for the effects of glyburide on the synthesis and release of insulin and insulin gene expression in isolated islets was investigated. On incubation for 1 h, glyburide increased insulin release without affecting either the insulin content or the PPI mRNA level. H-7, an inhibitor of PKC, inhibited the glyburide-induced insulin release, while H-8, an inhibitor of cyclic nucleotide-dependent protein kinases, did not affect the glyburide-induced insulin release. On incubation for 20 h, glyburide increased insulin release and the PPI mRNA level, without affecting the insulin content. H-7 inhibited glyburide-induced insulin release and increased the PPI mRNA level. H-8 significantly inhibited both the glyburide-induced increase in insulin release and increase in PPI mRNA level. In conclusion, glyburide stimulated insulin release via a PKC-mediated pathway and increased the PPI mRNA level via cyclic nucleotide-dependent protein kinase(s).

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1993

Fusion of dioleoylphosphatidylcholine vesicles induced by an amphiphilic cationic peptide and oligophosphates at neutral pH.

Peptide E5 is an analogue of the fusion peptide of influenza virus hemagglutinin and K5 is a cationic peptide which has an arrangement of electric charges complementary to that of E5. We reported that a stoichiometric mixture of E5 and K5 caused fusion of large unilamellar vesicles (LUV) of neutral phospholipids (Murata, M., Kagiwada, S., Takahashi, S. and Ohnishi, S. (1991) J. Biol. Chem. 266, 14353-14358). K5 caused fusion of LUV composed of dioleoylphosphatidylcholine (DOPC) at pH > 10, but not at neutral pH. In the presence of oligophosphates, such as 1 mM ATP, GTP, or polyphosphate, K5 caused rapid and efficient fusion of DOPC LUV at neutral pH without hydrolysis of oligophosphate groups, but another anions such as citrate, acetate, AMP, phosphate, or EDTA were ineffective. The peptide/oligophosphate-induced fusion behaviors have been investigated by a fluorescence resonance energy transfer assay for lipid mixing of LUV and negative staining electron microscopy. At higher ionic strengths ( > 0.3 M KCl) or in the presence of 5.0 mM MgCl2, the fusion was inhibited. Even at the inhibitory conditions, the association of K5 with lipid vesicles at neutral pH was directly confirmed by the Ficoll gradient assay method and by blue shifts of the tryptophan fluorescence of the peptide. A nonhydrolyzable GTP analogue, GTP gamma S, also induced fusion. These observations suggested that the electrostatic interactions between the positive and negative charges of K5 and oligophosphate, respectively, induced complex formation, triggering membrane fusion.

Adenosine Triphosphate↗
PubMed1993

A pH induced two-dimensional crystal of membrane-bound Na+,K(+)-ATPase of dog kidney.

Two-dimensional crystals of membrane-bound Na+,K(+)-ATPase were formed in acidic media and their qualities were investigated by electron cryo-microscopy as well as by conventional electron microscopy. At pH 4.8 in sodium citrate buffer, the best crystallization condition, more than 80% of membranes formed crystals. The high ratio allowed high-resolution images to be taken by electron cryo-microscopy. Image processing revealed that they had unique lattice constants (a = 108.7 A, b = 66.2 A, gamma = 104.2 degrees) and had few defects in the crystalline arrays. The reconstituted Fourier map of the ice-embedded crystal showed that there are two high contrast parts in one unit cell.

Animals↗
PubMed1993

Posterior fracture-dislocation of the thoracic spine without neurologic deficit. A case report and short literature review.

The authors present a case of posterior fracture-dislocation of the thoracic spine without neurologic deficit. A 63-year-old man injured by traffic accident. His spinal fracture-dislocation was treated conservatively because of his complications. At the present time, approximately 1 year after the injuries, the patient does not have any neurologic complaint. Conservative treatment should be adopted as the first choice in patients at older ages and in those with underlying diseases or serious complications.

Accidents, Traffic↗
PubMed1993

[Body composition, VO2 max and O2 debt max in elite senior high school male cyclists].

This study was performed to evaluate the physical resources for elite male cyclists of senior high school. Nine track cyclists (mean age, 17.4 years) and seven road cyclists (mean age, 17.3 years) were examined for body composition and cardiorespiratory function (VO2 max and O2 debt max), from 1988 to 1992. These measurements were compared with those of elite junior cyclists, and the progress of physiological function due to one-year training was examined for 7 cyclists. The results were as follows: 1. The mean parameters for track cyclists were recorded: percentage body fat (%Fat): 10.3%; lean body mass (LBM): 56.5kg; VO2 max: 3.93l/min, 62.5ml/kg.min; O2 debt max: 8.81l, 139.1ml/kg. 2. The mean parameters for road cyclists were recorded: %Fat: 10.9%; LBM: 54.9kg; VO2 max: 3.78l/min, 61.4ml/kg.min; O2 debt max: 7.89l, 128.4ml/kg. 3. The average %Fat, LBM, LBM/Ht, VO2 max and O2 debt max were not significantly different between track and road cyclists. 4. The average %Fat and VO2 max (ml/kg.min) of track and road cyclists were similar to those of elite junior cyclists. 5. By training for one year, the average VO2 max (ml/kg.min) and O2 debt max (ml/kg) showed a significant increase of approximately 13.6% and 22.6% respectively. These results indicated that through training 9 track and 7 road cyclists had achieved a superior body composition, aerobic work capacity and anaerobic work capacity, equal to those of elite junior cyclists.

Adolescent↗
PubMed1993

Vestibular neuronitis evaluated by the combined galvanic test.

Forty-two patients with unilateral vestibular neuronitis were examined by the combined galvanic test (CGT), consisting of the galvanic eye movement test (GEMT) and the galvanic body sway test (GBST). Results of the CGT were evaluated with respect to the time period from the onset of vestibular neuronitis. A favorable recovery was observed earlier with the GBST than the GEMT. We believe that this discrepancy may be due to the difference in compensation between the vestibulo-ocular reflex and the vestibulo-spinal reflex.

Adult↗
PubMed1993

[Body composition (densitometry-hydrostatics), skinfold thickness, BMI and their relationships in junior high school girls].

A study was conducted to evaluate body composition (Hydrostatics = Under-Water Weighing), skinfold thickness, and BMI in 97 junior high school girls, aged 12 to 15, in Nagasaki City. Body density was measured by under-water weighing, and the two compartments--fat weight (Fat) and lean body mass (LBM, or fat free weight: FFW)--were calculated using the formulas of Brozek et al. The results were as follows; 1. Mean values of body density were 1.0501 in first grade girls, 1.0476 in the second grade, and 1.0466 in the third grade. 2. Mean values of percentage body fat (% Fat) were 21.1% in the first grade, 22.1% in the second and 22.5% in the third. 3. Lean body mass (LBM) and LBM/Height increased significantly with advance from the first to the third grade. 4. The correlation coefficient between percent body fat and the sum of two skinfold thicknesses, the sum of three skinfold thicknesses, or the sum of seven skinfold thicknesses were 0.81, 0.80, and 0.82 respectively and all statistically significant (p < 0.001). 5. The correlation coefficient between BMI and the sum of two skinfold thicknesses, the sum of three skinfold thicknesses (r = 0.841) or the sum of seven skinfold thicknesses were 0.85, 0.84, and 0.84 respectively, and all statistically significant (p < 0.001). 6. Mean values of BMI, WSR, ASR, and WHR in all subjects (n = 97) were 19.6, 0.72, 0.39 and 0.43 respectively.

Adolescent↗
PubMed1992

Functional signal peptide reduces bilayer thickness of phosphatidylcholine liposomes.

To investigate the interaction between a signal peptide and the lipid bilayer, two kinds of peptides, L8-M5 (L8 = MRL8PLAALG, M5 = KVFER) and L14-M5 (L14 = MRL14PLAALG), were examined in membranes composed of dioleoylphosphatidylcholine (DOPC). Peptides L8 and L14 are artificially designed signal sequences, and M5 is the N-terminal five residues of human lysozyme; L8 mediated effective secretion of human lysozyme in yeast, while L14 did not [Yamamoto, Y., et al. (1987) Biochem. Biophys. Res. Commun. 149, 431-436]. DOPC liposomes incorporating L8-M5 or L14-M5 were observed by electron cryomicroscopy as pairs of concentric circles, and the separation of the bilayer was measured along the membrane. Peptide L8-M5 was found to reduce the bilayer thickness, but L14-M5 did not. CD measurements revealed that L8-M5 adopted an alpha-helical conformation with random coil in the liposome membranes and that L14-M5 adopted a more helical and less random conformation than L8-M5. Fluorescence spectroscopy using both aqueous and membranous probes revealed that L8-M5 destabilized the lipid bilayer more strongly than L14-M5. These results suggest that functional L8-M5 reduces the bilayer thickness and destabilizes the lipid bilayer and that these activities are important for signal peptide function.

Amino Acid Sequence↗