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Biomedical subjects

T Nagata

Publications and source records attributed to T Nagata.

At least 523 records · Page 29Linked to original sources
PubMed1987

Quantitative analysis of glucose after transient ischemia in the gerbil hippocampus by light and electron microscope radioautography.

Changes in glucose uptake in the gerbil hippocampus were studied by high-resolution [3H]2-deoxyglucose radioautography under sham and postischemic conditions. Sections of dorsal hippocampi were fixed by chemical fixatives or rapid-freezing and freeze-substitution techniques. Light and electron microscope radioautograms showed that the cell soma of each CA1 neuron subjected to transient ischemia revealed various degrees of glucose uptake. In the neuropil of the CA1 stratum radiatum, glucose uptake was higher in the thin dendrites of the ischemic group. Cell damage due to transsynaptic stimulation is suggested by these results.

Animals↗
PubMed1987

Forensic toxicological analysis of tetrahydrofuran in body materials.

Routine analysis of tetrahydrofuran (THF) in biologic materials has become feasible using GC and GC/MS and the headspace method. Problems of the headspace method and this substance which has a high water- and lipid-solubility were overcome by using the salting-out technique. Identification was made by mass spectral examination, in case of concentrations over 5 micrograms per sample. For quantitative determinations, tetrahydropyran (pentamethylene oxide) was used as an internal standard in GC, and a stable isotopic substance, octadeuterated THF (TDF) in GC/SIM. THF was detected in 1 microgram per sample by GC, and 0.1 microgram per sample by GC/SIM. THF blood levels in laboratory animals reached their highest values about 1 h after the oral administration, and the half-life was about 5 h. Ratios of tissue levels to blood were ca. 1.5-2 in the adipose tissue and kidney, and fairly equal in the brain, liver, spleen, and muscle.

Animals↗
PubMed1987

Evaluation of a new dense-porous hydroxylapatite endosteal dental implant.

A new hydroxylapatite implant with a dense and porous part, improved the implant neck-lamina propria interface when placed in that alveolar bone of dogs. Bone tissue was formed on the surface of the porous part above the ridge of the alveolar bone and fibrous bands from the lamina propria surrounding the neck of the implant were anchored into this newly formed bone. The new tissue structure was very similar to that of natural teeth and gingiva. Quantitative histologic analysis indicated that this tissue arrangement provided protection against bacterial invasion and reduced gingival pocket formation.

Alveolar Process↗
PubMed1987

Production rate of planktonic bacteria in the north basin of lake biwa, Japan.

Vertical and seasonal variations in the cell number and production rate of planktonic bacteria were investigated at a pelagic site (water depth, ca. 72 m) of the north basin of Lake Biwa during April to October 1986. The [methyl-H]thymidine uptake rate into a cold trichloroacetic acid-insoluble fraction and the frequency of dividing cells (FDCs) were measured for each sample as indices of the bacterial production rate. The seasonal data of bacterial number, thymidine uptake rate, and bacterial growth rate based on the FDCs were correlated with one another (rank correlation analysis, P < 0.05). These bacterial variables were not correlated positively with the chlorophyll a concentration. Vertically, the maxima of both bacterial number and the thymidine uptake rate were found in the euphotic zone. The direct counting of bacteria and the measurements of thymidine uptake rate combined with the size-fractionation method revealed that more than 90% of the bacterial biomass and production rate were attributed to unattached bacteria throughout the investigation period. The carbon flux estimates of bacterial production were less certain due to the variability of the conversion factor for the thymidine uptake method and that of the calibration for the FDC method, but even when the conservative range of bacterial net production rate was used (5 to 60 mug of carbon per liter per day), it can be suggested that bacterial net production in the investigated area was a significant fraction (ca. 30%) of the level of the primary production rate in the same water basin.

Journal Article↗
PubMed1987

Requirement of the Escherichia coli dnaA gene function for ori-2-dependent mini-F plasmid replication.

The mini-F plasmids pSC138, pKP1013, and pKV513 were unable to transform Escherichia coli cells with a dnaA-defective mutation under nonpermissive conditions. The dnaA defect was suppressed for host chromosome replication either by the simultaneous presence of the rnh-199 (amber) mutation or by prophage P2 sig5 integrated at the attP2II locus on the chromosome, both providing new origins for replication independent of dnaA function. The dnaA mutations tested were dnaA17, dnaA5, and dnaA46. dnaA5 and dnaA46 are missense mutations. dnaA17 is an amber mutation whose activity is controlled by the temperature-sensitive amber suppressor supF6. Under permissive conditions in which active DnaA protein was available, the mini-F plasmids efficiently transformed the cells. However, the transformants lost the plasmid as the cells multiplied under conditions in which DnaA protein was inactivated or its synthesis was arrested. As controls, plasmids pSC101 and pBR322 were examined along with mini-F; pSC101 behaved in the same manner as mini-F, showing complete dependence on dnaA for stable maintenance, whereas pBR322 was indifferent to the dnaA defect. Thus, ori-2-dependent mini-F plasmid replication seems to require active dnaA gene function. This notion was strengthened by the results of deletion analysis which revealed that integrity of at least one of the two DnaA boxes present as a tandem repeat in ori-2 was required for the origin activity of mini-F replication.

Bacterial Proteins↗
PubMed1987

[Chronic toxicity and recovery tests of rokitamycin in beagle dogs].

Six-month oral chronic toxicity study and two-month recovery tests on rokitamycin (TMS-19-Q) were performed in Beagle dogs at daily doses of 90, 180 and 360 mg/kg. The results were summarized as follows: No death occurred to any animals in these experiments. In higher dosage groups (180 and 360 mg/kg), vomiting, salivation and reduction of body weight gain with decrease in food intake were observed. Body temperature and pulse rate were normal, and ECG, sperm and vaginal smear tests, urinalysis, blood and biochemical examinations also revealed normal values. No marked changes in organ weights, necropsy, histopathological and electron microscopic observations were detected.

Administration, Oral↗
PubMed1986

Forensic toxicologic analysis of methamphetamine and amphetamine in body materials by gas chromatography/mass spectrometry.

Qualitative and quantitative analysis of methamphetamine and amphetamine in biologic materials was carried out by gas chromatography/mass spectrometry. A deuterium-labeled methamphetamine was employed as an internal standard with a detection limit of 50 pg and absolute stability and reproducibility. Blood was found to be the best material for estimation of the toxicity of the stimulant drug. It can be replaced by muscle which contains methamphetamine concentrations close to those of blood. The authors' classification of the toxic blood levels of methamphetamine from therapeutic to fatal doses was confirmed by additional data obtained from new case studies.

Amphetamine↗
PubMed1986

Changed compounds of hydroxyzine in a human urine.

During a forensic toxicological GC/MS screening, changed compounds of hydroxyzine were found in a man's urine taken about 20 h after ingesting sake (Japanese liquor) and tranquilizers. The structures of those compounds were assigned to 4-chlorodiphenylmethane(I), p-chlorbenzophenone(III), norchlorcyclizine(IV), 7-(p-chloro-alpha-phenylbenzyl)-2-hydroxy-2H,3H-oxazolo-[3,2 -alpha] piperazine(V), 1-(p-chloro-alpha-phenylbenzyl)-4-methylpiperazine-3-one(VI), N-(p-chloro-alpha-phenylbenzyl)-N'-formylmethyl-N'- hydroxyethyl-1,2-ethenediamine(VII) and 1-(p-chloro-alpha-phenylbenzyl)-4-[2-ethoxy(2-ethoxy)-ethyl] piperazine(VIII) on the basis of the fragmentation patterns and relative retention times except VIII which was identified using the synthesized compound. I, V, VI, VII and VIII have not been reported previously, but the possibility of metabolites of hydroxyzine is still uncertain.

Biotransformation↗
PubMed1986

Purification of membrane polypeptides of rat liver peroxisomes.

Peroxisomes were obtained by sucrose density gradient centrifugation from the livers of di(2-ethylhexyl)phthalate-fed rats, and the membranes were prepared by carbonate extraction (Fujiki, Y., Fowler, S., Shio, H., Hubbard, A.L., & Lazarow, P.B. (1982) J. Cell Biol. 93, 103-110). The integrated membrane polypeptides were solubilized with sodium dodecyl sulfate, and purified by repeated polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Separation of 70 and 68 kDa polypeptides was not attempted in the present study because of their close migration in polyacrylamide gel electrophoresis. Other polypeptides with apparent molecular masses of 41, 27, 26, and 22 kDa were purified to near homogeneity. Antibodies were raised against these purified preparations. The 68 kDa polypeptide is suggested to be produced by the proteolytic modification of 70 kDa polypeptide, since the former increased concomitantly with decrease of the latter when the liver homogenate was incubated, and this change was prevented in the presence of leupeptin during the incubation. The 41 kDa polypeptide was a minor component. The 70 and 68 kDa polypeptides and 41 kDa polypeptide and their antibodies were cross-reactive, but the relation of these polypeptides was not clear. The 27 and 26 kDa polypeptides seemed to be another species of membrane polypeptides, although the relationship of these two polypeptides remains to be clarified. The 22 kDa polypeptide is not related to other membrane polypeptides. The results of immunoblot analysis of subcellular fractions of the liver and an electron microscopic immunocytochemical study to locate the antigenic sites with protein A-gold complex suggest that all of these polypeptides are localized on peroxisomal membranes. On proliferation of rat liver peroxisomes by administration of di(2-ethylhexyl)phthalate, a peroxisome proliferator, all of these polypeptides were markedly increased.

Animals↗
PubMed1986

Carbon and nitrogen content of natural planktonic bacteria.

A method of estimating carbon and nitrogen content per unit of natural bacterial cell volume was developed. This method is based on the difference in the retentiveness of bacteria between two kinds of glass fiber filter, GF/C and GF/F (Whatman, Inc., Clifton, N.J.). Biovolume and biomass (carbon and nitrogen content) of bacteria which passed through the GF/C but not the GF/F filter were estimated with an epifluorescence microscopy and a CHN analyzer, respectively. From seasonal determinations of natural planktonic bacteria in epilimnetic waters of a mesotrophic lake, the conversion factors of 106 fg of C/mum and 25 fg of N/mum were derived as average values. By using these values, the contribution of bacteria to the biomass of lake plankton is discussed.

Journal Article↗
PubMed1986

Immunocytochemical localization of D-amino acid oxidase in the central clear matrix of rat kidney peroxisomes.

Light and electron microscopic localizations of D-amino acid oxidase (DAO) in rat kidney was investigated using immunoenzyme and protein A-gold techniques. The enzyme was purified from rat kidney homogenate and its antibody was raised in rabbits. By Ouchterlony double-diffusion analysis and immunoblot analysis with anti-(rat kidney DAO) immunoglobulin, the antibody was confirmed to be monospecific. The tissue sections (200 micron thick) of fixed rat kidney were embedded in Epon or Lowicryl K4M. Semi-thin sections were stained for DAO by the immunoenzyme technique after removal of epoxy resin for LM, and ultra-thin sections of Lowicryl-embedded material were labeled for DAO by the protein A-gold technique for EM. By LM, fine cytoplasmic granules of proximal tubule were stained exclusively. Among three segments of proximal tubules, and S2 and S3 segments were heavily stained but the S1 segment only weakly so. By EM, gold particles indicating the antigenic sites for DAO were exclusively confined to peroxisomes. Within peroxisomes, the gold particles were localized in the central clear matrix but not in the peripheral tubular substructures. The results indicate that D-amino acid oxidase in rat kidney is present exclusively in peroxisomes in the proximal tubule and that within peroxisomes it is found only in central clear matrix and not in the peripheral tubular substructures.

Animals↗