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Biomedical subjects

S Kataoka

Publications and source records attributed to S Kataoka.

At least 145 records · Page 8Linked to original sources
PubMed1986

Single amino acid replacements affecting the thermostability of kanamycin nucleotidyltransferase.

Amino acid residues of the carboxyl-terminal region of kanamycin nucleotidyltransferase were modified using segment-directed mutagenesis. Six different mutant enzymes with single amino acid replacements were selected out of 59 clones by DNA sequence analyses. The mutant enzymes were purified and it was found that the thermostability of one mutant enzyme was identical to the wild type, whereas the other five were less thermostable at varying degrees. The data suggested that changes in the enzyme thermostability depend not only on the position but also on the species of amino acid residue replaced.

Base Sequence↗
PubMed1986

Acute effects of phenytoin on brainstem auditory evoked potentials: clinical and experimental study.

In a patient with phenytoin (PHE) intoxication, the brainstem auditory evoked potentials (BAEPs) were lost except for wave I and wave V. The patient recovered. In rats given PHE, we found changes in amplitude, morphology, and latency of BAEP. Within 5 minutes, all waves disappeared except for wave I, and soon thereafter all waves were lost, with PHE plasma concentration between 45.8 and 52.1 micrograms/ml or above. Ninety minutes after infusion, waves gradually reappeared. Loss of BAEP cannot be used as a criterion for brain death unless PHE intoxication is ruled out.

Adult↗
PubMed1985

Acyltransferase and acid hydrolase activities of the abalone photoreceptor cell.

In order to study the synthesis and degradation processes of the photoreceptor membranes in the abalone, Nordotis discus, the localization of acyltransferase and acid hydrolase activities, respectively, were determined at the electron-microscopic level. Acyltransferase activity was localized on the cytoplasmic sides of thick (greater than 10 nm) membranes of the following organelles: a few cisternae at the trans (or concave) side of Golgi apparatus, Golgi and probably related vesicles, short tubules, curved pentalaminar disks and limiting membranes of the phagosomal multivesicular bodies; all organelles were scattered in the peri- to supranuclear cytoplasm. The phospholipids, which are major components of the photoreceptor membrane, are considered to be synthesized by these membranes. Acid phosphatase activity was localized in the lumina of Golgi cisternae and vesicles, lysosomes, and smaller multivesicular and related bodies, but not in multilamellar bodies. The matrices of the larger multivesicular bodies and of the pigment granule complexes showed arylsulfatase activity. Vesiculated and autophagocytosed photoreceptor microvilli seemed to be degraded by acid hydrolases, forming multivesicular and related bodies. Supporting cells also showed acyltransferase and acid hydrolase activities.

Acyltransferases↗
PubMed1985

Elevated cholecystokinin-like activity in the duodenal mucosa in patients with cholecystolithiasis.

Cholecystokinin (CCK)-like activities in the duodenal mucosa of the patients with cholecystolithiasis were determined with the bioassay method we established. The results obtained are as follows: The gall bladder of the patients with cholecystolithiasis following oral administration of egg yolk has contraction rates comparable to those of the normal subjects in the control group, whereas the contraction rate of the gall bladder of the patients with cholecystolithiasis following administration of caerulein was markedly lower than that of the normal subjects in the control group. The variations in the contraction of the gall bladder in time lapse following administration of caerulein to the patients with cholecystolithiasis strongly denied the possibility of either insufficient release of CCK or accelerated dissimilation of CCK in those patients. Based on the above findings, it was concluded that the sensitivity of the gall bladder to CCK decreases in the patients with cholecystolithiasis and that, in order to replenish it, the feed-back mechanism reacts to sufficiently promote the production of CCK in the duodenal mucosa. The similar mechanism was noted in the variations of the findings of normal subjects as age advanced.

Adult↗
PubMed1985

Expression of receptors for Fc portion of IgM (Fc mu . R) and surface neuraminic acid on the human peripheral lymphocytes.

The purpose of this investigation is to establish a method of quantitation of sialic acid on the lymphocyte membrane surface and to clarify the importance of sialic acid in the functional manifestation of the lymphocyte receptor for the Fc portion of IgM (Fc mu . R) as well as the cell surface. The experiments yielded results leading to the following conclusions: Cell surface sialic acid can be exclusively recovered at consistent rates by treatment of lymphocytes with 0.1 IU of neuraminidase in the presence of Ca++ at 37 degrees C for 30 min. The sialic acid obtained, though in minute quantities, was accurately quantitated by the TBA method. By these procedures, the amount of sialic acid present on the cell membrane of human peripheral blood lymphocytes was determined to be 2.46 micrograms/10(7). Surface sialic acid on lymphocytes cultured at 37 degrees C after treatment with neuraminidase was resynthesized sufficiently at about 6 hr. On the cell membrane of lymphocytes deprived of Fc mu . R by treatment with neuraminidase, the receptor for IgM Fc became redetectable following incubation of the cells at 37 degrees C; the time-course of redevelopment of Fc mu . R showed a striking coincidence with that of sialic acid resynthesis. A sufficient redevelopment of Fc mu . R occurred in 6 hr of incubation of neuraminidase-treated Fc mu . R-deprived lymphocytes; the time required for sufficient redevelopment was comparable to that reported for pronase-treated lymphocytes. It is concluded from these findings that Fc mu . R deprived of sialic acid is no longer repaired while the receptor is resynthesized de novo on incubation of lymphocytes under adequate conditions.

Cell Membrane↗
PubMed1983

Immunologic aspects of the nonobese diabetic (NOD) mouse. Abnormalities of cellular immunity.

Experiments were performed on 12-wk-old nonobese diabetic (NOD) mice to investigate the immunologic background of the condition, using ICR mice as controls. The results indicate the following: (1) absolute decreases in number of T lymphocytes, (2) depression of natural killer activity, (3) normal responsiveness in delayed type hypersensitivity and functional depression of killer T cells against allogeneic tumors, (4) diminished resistance to herpes virus infection, and (5) enhanced production of polyclonal antibodies to T cell-dependent antigens. These features are similar to those noted in other autoimmune diseases of man and in their experimental models in laboratory animals. Elucidation of the pathogenetic mechanism of autoimmune diabetes mellitus in NOD mice, therefore, may contribute to the diagnosis, treatment, and prevention of a wide variety of autoimmune diseases.

Animals↗
PubMed1982

Detection of guinea pig T mu and T gamma cells by a double rosette assay.

By a rosette assay with ox red blood cells (ORBC) sensitised with rabbit IgM and IgG antibodies (EA mu and EA gamma), receptors for IgM (Fc mu-R) and IgG (Fc gamma-R) on the surface of guinea pig lymphocytes in the different lymphoid organs were demonstrated. A double rosette assay with rabbit erythrocytes (RRBC) and EA mu or EA gamma for detection of T cells with Fc mu-R (T mu) or Fc gamma-R (T gamma) was also developed. Fc mu-R was detected on 40.1%, 48.7%, 35.0% and less than 1% of peripheral blood, lymph node, spleen and thymus cells respectively. By a double rosette assay with RRBC and EA mu, approximately 30% of peripheral blood, lymph node and spleen T cells were identified as T mu cells. T gamma cells as revealed by a double rosette of RRBC and EA gamma were found to be 3% and 5% respectively of peripheral blood and lymph node T cells, whereas much higher numbers of T cells in the spleen (32.7) were identified as T gamma cells. This double rosette assay of T mu and T gamma cells in the peripheral blood of guinea pigs which had received prednisolone showed that the proportion of T mu cells decreased early after drug administration and that T gamma cells increased in number. Thus the methods provide a useful means of detecting T mu and T gamma cells in guinea pigs. This assay system for T mu and T gamma cells in guinea pigs should be useful for studies of their variation or functional significance in the immune response.

Animals↗
PubMed1982

Cholecystokinin-like activity in the duodenal mucosa of duodenal ulcer patients.

Cholecystokinin-like activity in the duodenal mucosa was measured by the bioassay method described by Ljungberg to elucidate its significance in 14 duodenal ulcer patients as well as in 13 normal subjects with no evidence of gastrointestinal diseases. The stage of duodenal ulceration was determined endoscopically according to the criterion of the Japanese Gastroenterological Endoscopic Society. The cholecystokinin-like activity in the duodenal mucosa of duodenal ulcer patients in active stage 1, which was considered as an early stage of active open duodenal ulceration, did not differ statistically from that of normal subjects, whereas that of duodenal ulcer patients in active stage 2 began to show a significant increase (p less than 0.05), and the cholecystokinin-like activity in the duodenal mucosa of duodenal ulcer patients in healing stage 1 or healing stage 2 was significantly higher than that in normal subjects (p less than 0.01). The cholecystokinin-like activity in the duodenal mucosa of duodenal ulcer patients in the scarring stage, however, returned to the normal range. It is concluded that cholecystokinin may act physiologically in the cure of duodenal ulcer.

Adolescent↗
PubMed1981

Diurnal changes in the fine structure of photoreceptors in an abalone, Nordotis discus.

In order to examined a diurnal (24 h) rhythm in the fine structure of photoreceptors of abalone, Nordotis discus, the animals were kept on a daily light-dark cycle (light period: 6:00 a.m.--6:00 p.m., 2--5 lx) for 10 days; subsequently their eyes were fixed at nine specified times of the day. At 5:30 a.m. the photoreceptors consisted of numerous terminal microvilli growing on the surface of a dome-shaped apical cytoplasmic process (AP). Illumination induced breakdown of the photoreceptive microvilli into many vesicles. These vesicles were densely aggregated on almost the entire surface of enlarged APs at 7:00 a.m. After 1 h they markedly decreased in number. The cell at 10:00 a.m. possessed sparse, short and irregularly-contoured microvilli. The microvilli gradually increased in number from the middle through the later half of the light period. Only within 1 h after deprivation of light shorter but characteristic terminal microvilli were observed. By midnight they became similar in fine structure to those at 5:30 a.m.

Animals↗
PubMed1981

Establishment of pigmented melanocyte culture strain from Harding-Passey melanoma.

A cultured cell strain of melanotic melanoma was established from Harding-Passey mouse melanoma. The established cells proliferated as a monolayer culture and actively produced melanin pigment. Under an electron microscope, these cells showed the typical characteristic features of the melanocyte. When a cell suspension was inoculated into Swiss mice, they developed typical melanocytic tumors which closely resembled the original melanomas.

Animals↗