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Biomedical subjects

J Nishikawa

Publications and source records attributed to J Nishikawa.

At least 145 records · Page 8Linked to original sources
PubMed1987

Synthesis and 3'-substituent effects of some 7 alpha-methoxy-1-oxacephems on antibacterial activity and alkaline hydrolysis rates.

Relationships between intrinsic antibacterial activity and beta-lactam chemical reactivity of 7 beta-(phenylacetamido)-7 alpha-methoxy-1-oxacephems with various 3'-substituents were studied in order to clarify the effect of the 3'-substituent on the antibacterial activity. The chemical reactivity of the beta-lactam ring estimated by pseudo-first-order rate constants log kobsdNMR of alkaline hydrolysis at pD 10.4 and 35.0 degrees C correlates well linearly with 13C NMR chemical shift differences (delta delta(4-3], infrared stretching frequencies of the beta-lactam carbonyl (vC = O), and sigma I values. Values of log (1/CN), averaged for the MIC values for Escherichia coli, E. coli NIH JC-2, E. coli EC-14, and Klebsiella pneumoniae SRC-1, were taken as an estimation of the intrinsic antibacterial activity. The log (1/CN) values of the compounds without good leaving groups correlated fairly well with log kobsdNMR values. The comparatively high antibacterial activity of compounds with good leaving groups may be attributable to the different course of decomposition of these compounds.

Anti-Bacterial Agents↗
PubMed1987

1H NMR study of degradation mechanisms of oxacephem derivatives with various 3'-substituents in alkaline solution.

The degradation process of oxacephems with various 3'-substituents in alkaline solution was examined by 1H NMR spectroscopy, and the structures of two types of degradation products were determined: the hydrolysis products having the cleaved beta-lactam ring and the remaining 3'-substituents, and the exo-methylene compounds having the cleaved beta-lactam ring and the expelled 3'-substituents. The oxacephems were found to decompose, giving the former compounds that subsequently decomposed to the latter compound. Although the ratios of the formation of the exo-methylene compound 15 relative to the other degradation products depended on the leavability of the 3'-substituents, there was little correlation between the relative yields and the beta-lactam reactivity. Thus, the expulsion of the leaving group at the 3'-position was concluded to be not involved in the nucleophilic attack on the beta-lactam carbonyl.

Cephalosporins↗
PubMed1987

Occurrence in Bacillus megaterium of uridine 5'-diphospho-N-acetylgalactosamine and uridine 5'-diphosphogalactosamine, intermediates in the biosynthesis of galactosamine-6-phosphate polymer.

We isolated two galactosamine derivatives from Bacillus megaterium sporulating cells by lectin affinity chromatography followed by DEAE-Sephadex A-25 chromatography. From chemical analyses and measurements of these compounds, it was determined that one was uridine 5'-diphospho-N-acetylgalactosamine and that the other was uridine 5'-diphosphogalactosamine. They appeared in the middle stage of sporulation and disappeared during the period when galactosamine-6-phosphate is deposited on the forespore surface. These results suggest that uridine 5'-diphospho-N-acetylgalactosamine and uridine 5'-diphosphogalactosamine are intermediates in the biosynthesis of the galactosamine-6-phosphate polymer, a backbone structure of the exosporium.

Bacillus megaterium↗
PubMed1987

Circadian rhythm of the liver of male rats dosed with phenobarbital--I. Organ weight, cellular structures, glycogen contents and mitotic activity.

The circadian rhythm of the liver, namely organ weight, cellular structures (by light-microscopy), glycogen content (by periodic acid-Schiff (PAS) reaction) and mitotic activity, was studied in 166 male Sprague-Dawley rats orally treated daily at 0800-0900 with 70 (study 1) or 50 (study 2) mg/kg phenobarbital (PB) for 7 days. Thereafter, eight (study 1) or five (study 2) rats each were studied at 4-hr intervals at 1000, 1400, 1800, 2200, 0200, 0600 and 1000 through till the following day. The lighting schedule in the colony was 12:12, light:dark (light from 0600 to 1800). The liver weight was raised in PB-treated rats at all times of the day compared to controls and showed a distinct circadian rhythm with a peak at 1000 and a minimum at 2200 in PB-treated rats and the controls. The circadian rhythm of cellular structures was closely related to the hepatic glycogen content which was in good agreement with the controls, but at 1400 and 1800 the glycogen particles were more distinctly diminished in the enlarged centrilobular hepatocytes of PB-treated rats. The mitotic activity of hepatocytes was markedly increased in rats treated with PB but showed the same circadian rhythm as controls with a peak at 1000.

Animals↗
PubMed1987

Circadian rhythm of the liver of male rats pre-treated with phenobarbital--II. Hexobarbital sleeping time and lipids content in liver and serum.

The circadian rhythm of hexobarbital sleeping time and lipids content in liver and serum were studied in 226 male Sprague-Dawley rats pretreated daily at 0800-0900 with 70 mg/kg (study 1 or 3) or 50 mg/kg (study 2) phenobarbital (PB) orally for 7 days. Thereafter, eight (study 1) or five (study 2 and 3) rats each were studied at 4-hr intervals at 1000, 1400, 1800, 2200, 0200, 0600 and 1000 through the following day. The lighting schedule in the colony was 12:12 +/- light:dark (light from 0600 to 1800). The hexobarbital sleeping times of PB-pretreated rats were generally shortened compared to the controls and no circadian rhythm was observed. PB-treatment increased slightly the liver content of cholesterol, and significantly that of triglycerides and phospholipids. Liver cholesterol and phospholipids showed circadian rhythms with peaks during the dark phase. No circadian rhythm of liver triglycerides existed. In serum, levels of triglycerides and phospholipids were slightly lowered by PB-treatment, while levels of cholesterol and beta-lipoprotein were not influenced. Serum values did not exhibit circadian rhythms.

Animals↗
PubMed1987

[A cooperative group study of clinical efficacy of the liver SPECT].

The purpose of this study is to evaluate the clinical efficacy of the liver SPECT about detectability of SOLs (space occupying lesion). The images were interpreted with the planar scintigram (PS) only and combination of PS and SPECT (single photon emission computed tomography) by 11 physicians. Changes of false positive and false negative rate were calculated to evaluate the influence of the diffuse parenchymal liver disease and the localization of the SOLs. Addition of SPECT to PS in the cases who are suspected SOLs is effective in right hepatic lobe (right anterior and posterior segment) to detect the SOLs, but not effective in left lateral segment. Addition of SPECT to PS in the cases with diffuse parenchymal liver disease and SOLs increases the false positive rate.

Chronic Disease↗
PubMed1987

[Left ventricular short-axis plane for magnetic resonance imaging: its clinical importance and applications].

Left ventricular short-axis images were obtained by ECG-gated magnetic resonance imaging (MRI) in nine patients with hypertrophic cardiomyopathy and seven patients with chest pain, all of whom had diagnostic cardiac catheterization including angiography. The accuracy and usefulness of the short-axis image in MRI for measuring wall thickness and dimension and for calculating ejection fraction were evaluated. All patients were examined on an examination couch in the right anterior oblique position in optimal positions to obtain the left ventricular long-axis images in the Z-X plane (conventional coronal plane). Next, the paraxial mode was used to obtain the short-axis images by rotating the Y-Z plane (conventional sagittal plane) around the Y axis. The intervals between the trigger on the middle point of the upstroke of the R wave and the 90 degree pulse of saturation recovery spin echo sequence were 40 msec and 340 msec with a 34 msec echo delay time for the end-diastolic and end-systolic images, respectively. Short-axis images in MRI in end-diastole were utilized to measure wall thickness and dimension in patients with hypertrophic cardiomyopathy and the measurements obtained were compared with those of echocardiography. As for calculating ejection fraction in patients with chest pain, the length of the left ventricular long axis (L) was measured using the MRI long-axis image. The intraventricular sectional area at four levels (S1, S2, S3, S4) were measured using the MRI short-axis image in end-diastole and in end-systole. Left ventricular end-diastolic and end-systolic volumes were calculated using the following formula: V = 1/2 X (L -4.5) X S1 + 1.5 X (S1 + S2 + S3) + 1/3 X 1/2 X (L -4.5) X S4. Ejection fraction by MRI was compared with that by cardiac catheterization (single plane, area-length method). The measurements of wall thickness and dimension by MRI correlated well with those by echocardiography (r = 0.97, p less than 0.01). Ejection fraction calculated by MRI correlated significantly with that by cardiac catheterization (r = 0.82, p less than 0.05). We concluded that the left ventricular short-axis image in MRI is satisfactorily accurate for measuring wall thickness and dimension, and useful for evaluating the left ventricular ejection fraction.

Angina Pectoris↗
PubMed1987

Evaluation of regurgitant fraction of the left ventricle by gated cardiac blood-pool scanning using SPECT.

Regurgitant fraction (RF) of patients with and without mitral regurgitation (MR) and/or aortic regurgitation (AR) was evaluated by gated cardiac blood-pool scanning using single photon emission computed tomography (SPECT). Using the stroke count image of a short-axis tomogram to separate the right atrium and ventricle, the left ventricular stroke count (LVSC) and right ventricular stroke count (RVSC) were determined. The RF equaled (LVSC - RVSC)/LVSC. Calculated RF in 14 subjects without significant regurgitation by contrast angiography was 5.8 +/- 5.9% (mean +/- s.d.), RF of 17 cases with angiographic regurgitation was 42.5 +/- 16.8% (p less than 0.001). The sensitivity of the radionuclide method compared to angiography was 94% (16/17 cases), and specificity was 100% (14/14 cases). RF of mild Re (1+ or 2+) was 26.0 +/- 8.9% (n = 6) and RF of severe Re (3+ or 4+) was 51.5 +/- 12.7% (n = 11) (p less than 0.001). Correlation between the RF determined with the radionuclide method and with cardiac catheterization was good (y = 5.85 + 0.700 x, r = 0.821, n = 17). We conclude that RF of MR and/or AR can be accurately evaluated by gated cardiac blood-pool scanning using SPECT.

Cardiac Catheterization↗
PubMed1986

Scintigraphic manifestation of fibrous dysplasia.

Scintigraphic manifestations of fibrous dysplasia were analyzed in 59 lesions of 26 patients (12 monostotic, 14 polystotic). Bone imaging with Tc-99m MDP revealed a high percentage of increased uptake of radioisotope in the lesions of fibrous dysplasia. Four (14%) of 29 cystic lesions and two (7%) of 30 lesions with the appearance of ground glass showed no increase in radioisotope uptake, although roentgenograms showed marked changes. Therefore, care must be taken in the diagnosis of fibrous dysplasia with bone imaging alone. Nuclear methods, however, are indispensable in evaluating the dynamic aspects of bone mineral behavior and in demonstrating disease where none was suspected, or in visualizing polyostotic involvement in those cases where only monostotic disease was suspected clinically. It is concluded that both scintigrams and roentgenograms are complementary procedures in the diagnosis of fibrous dysplasia.

Adolescent↗
PubMed1986

Appearance of uridine 5'-diphospho-N-acetylglucosamine-4-epimerase during sporulation of Bacillus megaterium.

In a biosynthetic study of the spore coat of Bacillus megaterium ATCC 12872 spore with galactosamine phosphate as a major component of the outer coat, high-performance liquid chromatography (HPLC) and enzyme immunoassay were applied for the measurement of UDP-N-acetylglucosamine-4-epimerase [EC 5.1.3.7] activity and the enzyme protein concentration, respectively. The new HPLC system using an ion-pair (or anion-exchange) column allowed us to determine successfully the enzyme activity and its application, proving that the specific activity of the enzyme in the cells increased at the later stage of sporulation. This increase in activity was parallel to the induction of enzyme protein synthesis, which was detected by sandwich enzyme immunoassay using antiserum to the purified enzyme. These results suggested that the regulation of this enzyme is at the genetic level and it plays an important role in the outer coat synthesis in the later sporulation stage of B. megaterium.

Bacillus megaterium↗
PubMed1985

Germination of the decoated spores of Bacillus megaterium.

Decoated spores of Bacillus megaterium ATCC 12872 were prepared by extracting the inner coat components with an alkaline solution containing sodium dodecyl sulfate and dithiothreitol (SDS-DTT) from outer coat-deficient mutant spores, which were produced from one of the mutants isolated and named MAE-05 by us. The decoated mutant spores germinated as well as the intact spores of the mutant and the parent, indicating that the outer and inner spore cats cannot be essential structures for the initiation of germination. When the SDS-DTT-treated MAE-05 spores were converted to H-spores by incubation in citrate-phosphate buffer (pH 3.5) at 30 C for 3 hr, they lost their germinability by glucose and KNO3. Ca-spores, prepared by treating H-spores with 10 mM calcium acetate at 37 C for 60 min, regained the germinability. Experiments on the interaction of 45Ca with the cortex and the inner membrane isolated from H-spores suggested that the calcium present in the inner membrane might be related to germinability.

Bacillus megaterium↗