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C Miyazaki

Publications and source records attributed to C Miyazaki.

83 records · Page 5Linked to original sources
PubMed1985

Genetic manipulation of membrane phospholipid composition in Escherichia coli: pgsA mutants defective in phosphatidylglycerol synthesis.

Unique mutants of Escherichia coli K-12, defective in phosphatidylglycerol synthesis, have been isolated from a temperature-sensitive strain incubated at its nonpermissive temperature. The parent strain had excess phosphatidylglycerol by harboring both the pss-1 allele [coding for a temperature-sensitive phosphatidylserine synthase (EC 2.7.8.8)] and the cls- allele (responsible for a defective cardiolipin synthase). The newly acquired mutations caused better growth at higher temperatures. One of the mutations (pgsA3) has been identified in the structural gene for phosphatidylglycerophosphate synthase [glycerophosphate phosphatidyltransferase (EC 2.7.8.5)]. Phospholipid compositions of these mutants were remarkable; phosphatidylethanolamine was the sole major lipid. In media with low osmotic pressures, these cells grew more slowly than the wild-type cells. They grew normally without recovering from the phospholipid abnormality in media appropriately supplemented with sucrose and MgCl2. Formation of cardiolipin and phosphoglycerol derivatives of membrane-derived oligosaccharides was reduced in a pgsA3 mutant. E. coli strains having the pgsA3, pss-1, and cls- mutations, either individually or in combination, constitute an empirical system in which the molar ratio of three major membrane phospholipids can be variously altered.

Cardiolipins↗
PubMed1985

Biosynthesis of novel acidic phospholipid analogs in Escherichia coli.

When cultured in the presence of 600 mM D-mannitol, Escherichia coli K-12 cells synthesized two novel phospholipids. The identities of these compounds are postulated to be phosphatidylmannitol and diphosphatidylmannitol, the sugar alcohol analogs of phosphatidylglycerol and cardiolipin, respectively. The nonacylated glycerol moieties of the normal acidic phospholipids were substituted by D-mannitol. The formation of the analogs was significantly enhanced when strains harboring the pss-1 allele, a temperature-sensitive mutation in phosphatidylserine synthase (Ohta and Shibuya, J. Bacteriol. 132:434-443, 1977), were grown at 42 degrees C, and the accumulation of the analogs was maximum in late stationary phase; more than 90% of the total cellular lipids were these novel phospholipids. Strains with a defective cardiolipin synthase (Pluschke et al., J. Biol. Chem. 253:5048-5055, 1978) failed to form the analog lipids, whereas cells with increased cardiolipin synthase activity due to the presence of a pBR322-derived recombinant plasmid containing the structural gene for cardiolipin synthase produced more mannitol lipids than wild-type strains. These observations and the structures of the analog lipids indicated that cardiolipin synthase participates in the formation of these novel phospholipids. We suggest that reversible alcoholysis and condensation, in addition to low substrate specificity of the enzyme, are the mechanisms involved in this process. Addition to the medium of other straight-chain alditols, D-arabitol, ribitol, xylitol, erythritol, and L-threitol also yielded pairs of novel phospholipids, whereas sorbitol or galactitol produced only one analog in small quantities. These acidic phospholipid analogs have not been reported in any living system. They should be useful in the study of structure-function relationships of phospholipids and in manipulating the structures of various membrane systems.

Escherichia coli↗
PubMed1985

Alteration of phospholipid composition by combined defects in phosphatidylserine and cardiolipin synthases and physiological consequences in Escherichia coli.

Escherichia coli K-12 derivatives with a common genetic background carrying, either alone or in combination, the pss-1 allele coding for a temperature-sensitive phosphatidylserine synthase (A. Ohta and I. Shibuya, J. Bacteriol. 132:434-443, 1977) and cls- for a defective cardiolipin synthase (G. Pluschke et al., J. Biol. Chem. 253:5048-5055, 1978) were constructed. The phospholipid polar headgroup compositions of these strains were significantly different from each other depending on their genotypes and growth temperature, whereas other membrane characteristics such as the total phospholipid content, fatty acid composition, membrane protein profile, and lipopolysaccharide content were practically the same, suggesting that the phenotypes of these strains were the direct consequences of abnormalities in membrane phospholipid composition. The cls pss-1 double mutation caused an unusual accumulation of phosphatidylglycerol with an extremely low content of cardiolipin. The cls mutation alone was found to give a growth defect, and its introduction into a pss-1 mutant resulted in an enhanced temperature sensitivity of growth. Addition to a broth medium of a proper concentration of sucrose, NaCl, Mg2+, or Ca2+ allowed the growth of a pss-1 mutant at otherwise nonpermissive temperature, but a pss-1 cls double mutant required the combined addition of sucrose or NaCl and MgCl2 for full growth at 42 degrees C. The possible mechanisms for these physiological consequences of the mutations are discussed on a molecular basis. The remedial effects of culture supplements allowed the pss-1 mutants to grow at 42 degrees C resulting in enhanced abnormalities of membrane phospholipid composition.

CDPdiacylglycerol-Serine O-Phosphatidyltransferase↗
PubMed1984

Rotavirus infection of young children in two districts of Kenya from 1982 to 1983 as analyzed by electrophoresis of genomic RNA.

Employing techniques of polyacrylamide gel electrophoresis of viral RNA segments, we studied rotavirus strains and their relative contributions to rotavirus gastroenteritis epidemics in two major districts of Kenya. From early 1982 to the middle of 1983, 18 representative electropherotypes, including 6 short strains, were detected in 30 rotavirus specimens obtained from Nairobi, whereas 16, including 3 short strains, were detected in 70 virus specimens from coastal areas. With the exception of one strain, there were no identical electropherotypes between the two groups of rotaviruses obtained from these different districts. A change in predominant electropherotypes was observed in Mombasa in early 1983, and subsequently, newly occurring strains were detected in a small town along the coast when an apparent increase in gastroenteritis was observed in the district.

Child, Preschool↗
PubMed1984

Potentiation of anticancer agents by new synthetic isoprenoids. I. Inhibition of the growth of cultured mammalian cells.

In this study, 9 new synthetic isoprenoids with 9-10 isoprene chains were tested. One-fifth of the D10 value (concentration of drug that reduced colony-formation ability to 10% that of control) for each isoprenoid was calculated from dose-response curves of Chinese hamster V79 cells or human HeLa cells in culture. That dose was combined with various anticancer agent [1-(4-amino-2-methylpyrimidin-5-yl)methyl-3-(2-chloroethyl)-3-n itrosurea HCl, bleomycin A2 (BLM), cisplatin, doxorubicin (Dx), 5-fluorouracil, mitomycin, and 6-mercaptopurine] to test whether isoprenoids can potentiate the cytotoxic effect of anticancer agents against cultured mammalian cells. Among the 9 isoprenoids tested, decaprenoic acid, dacaprenylamine.HCl, and N-(p-methylbenzyl)decaprenylamine.HCl significantly potentiated BLM and Dx. Some isoprenoids increased intracellular levels of anticancer agents. Both enhanced uptake and reduced efflux of Dx were observed.

Animals↗
PubMed1984

Imidazole-resistant phenotype and virus transformation in cultured rat cells.

Compared to an untransformed rat cell line, 3Y1, adenovirus 12-transformed cell lines of 3Y1 were highly sensitive to the cytotoxic action of an imidazole antibiotic, clotrimazole. In contrast, SV40-transformed rat cell lines derived from the 3Y1 cell line showed no appreciable difference in the response to clotrimazole when compared to 3Y1 cells. Clotrimazole-resistant clones, WCT-1 and WCT-2, which were spontaneously isolated from the adenovirus 12-transformed cell line W5, showed 5- to 10-fold higher resistance than did W5; the dose-response curves of clotrimazole-resistant clones were similar to those of the untransformed 3Y1 cells. The growth of 3Y1 cells was blocked in the presence of 1% serum, whereas those of W5, WCT-1, and WCT-2 cells were only slightly affected by the same dose of serum in the medium. The membrane fractions of 3Y1, W5, and WCT-1 cells were found to contain similar cholesterol:phospholipid ratios. The phospholipid composition in the membrane fraction of line WCT-1 was similar to that of line W5 but not to that of line 3Y1. By contrast, the fatty acid composition was specifically altered in clotrimazole-resistant clones; cellular contents and some species of fatty acid such as 16:1, 18:2, and 20:4 in WCT-1 and WCT-2 cells were similar to those of 3Y1 but not to those of W5 cells. Differential sensitivities of various cell lines to clotrimazole are discussed in relation to the lipid composition.

Animals↗
PubMed1975

Carisoprodol in the treatment of myofascial pain-dysfunction syndrome.

The effects of carisoprodol and a placebo were compared in a sample of 60 patients with the clinical diagnosis of myofascial pain-dysfunction syndrome using double-blind design. Carisoprodol failed to show a significantly greater effect than the placebo. The side effects were about the same with both agents.

Adolescent↗
PubMedDate not supplied

Evoked potentials in neonates and infants with aseptic meningitis.

We investigated 4 infants with aseptic meningitis, 4-38 days of age, by repeated electroencephalography (EEG), flash-visual evoked potentials (F-VEPs), and brainstem auditory evoked potentials. The patients all had mild, acute phases and favorable outcomes at 1-2 years of age. EEGs and F-VEPs obtained within 1 month after onset all were defined as abnormal. In 3 patients, EEG findings were normal 1-2 months after onset, while F-VEP findings were normal at 9-10 months. Brainstem auditory evoked potential findings were normal, except for 1 with otitis media. Evoked potentials suggested that subclinical brain damage, especially due to cortical lesions, persisted during the first year of life in these patients clinically diagnosed with "meningitis."

Evoked Potentials, Auditory↗
PubMedDate not supplied

Laxative poisoning: toxicological analysis of bisacodyl and its metabolite in urine, serum, and stool.

An 11-year-old boy was hospitalized because of severe diarrhea (over 5 L/day). The child survived; however, the diarrhea continued while he was given intravenous fluids and his electrolyte balance was closely supervised. Based on observation of the patient and his family in the hospital, surreptitious administration of a poison by his mother was suspected, and toxicological analysis was carried out on stools from the boy and on medicine administered to him by his mother. Bisacodyl, a cathartic with a direct effect on the colon, was detected in the medicine, and a metabolite of bisacodyl was present in the stool. We devised a sensitive and reliable method to quantitate the bisacodyl metabolite in urine and serum. The sample was incubated with beta-glucuronidase at 37 degrees C for 2 h; bisacodyl metabolite was extracted with tert-butyl methyl ether, then derivatized by methylation, and subjected to gas chromatography-mass spectrometry. Bisphenol A was used as an internal standard. The calibration curve was linear in the concentration range from 2 to 1000 ng/0.2 mL, and the lower limits of detection were 1 ng/0.2 mL for the urine and 2 ng/0.2 mL for the serum. As concentrations of bisacodyl metabolite in the urine and serum of the patient were clearly defined, perhaps such investigations are warranted before extensive clinical therapy is prescribed.

Bisacodyl↗