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Biomedical subjects

T Shibata

Publications and source records attributed to T Shibata.

At least 919 records · Page 51Linked to original sources
PubMed1986

Ampicillin concentrations in human serum and periodontal membrane following a single oral administration of bacampicillin.

Ampicillin concentrations in human serum and periodontal membrane after a single oral administration of bacampicillin (500 mg) were assayed by the agar diffusion (paper disc) method. The peak times of serum and periodontal membrane were nearly identical, being approx. 90 min after administration. The peak concentrations of serum and periodontal membrane were 12.81 micrograms/ml and 6.97 micrograms/g, respectively. The concentration ratio of periodontal membrane to serum at the peak time was 0.56.

Adult↗
PubMed1986

Activity, cardiac and respiratory responses of blindfold preterm infants in a neonatal intensive care unit.

The purposes of the present study were to examine 24-h periods in the life of preterm infants incubated in a Neonatal Intensive Care Unit (NICU) using indices of activity, cardiac and respiratory responses, and to examine the effects of blindfolding incubated infants upon these behavioural indices. Ten healthy preterm infants were individually observed for 2 days a week for a 24-h period, using a continuous video recording system. Each infant was blindfolded with an eye-mask and a black head-cap for approximately equal to 10 h during a night out of the 2 days. Analyses on activity, cardiac and respiratory responses were done for (1) 20 min sampled from every other hour during the 2 days, and (2) for 1 h during the night, both a blindfolded day and unblindfolded, respectively. The results showed that activity was less and respiration rate lower when blindfolded than when unblindfolded. Respiration rate was also found to be stable when blindfolded.

Birth Weight↗
PubMed1986

The use of the monoclonal antibody Ki-67 in the identification of proliferating cells: application to surgical neuropathology.

In order to test its potential application to surgical neuropathology, the monoclonal antibody Ki-67 was used to demonstrate immunohistochemically the proliferating cells in 40 neoplasms of the nervous system. The antibody, which reacts with a nuclear protein expressed in the G1, G2, S, and M phases of the cell cycle, was demonstrated in frozen sections of all lesions. The highest incidence of stained nuclei was found in a metastatic carcinoma (57%). The percentage of stained cells in gliomas was in general agreement with the histologic grade and known biologic behavior of the lesions, ranging from 0.6% in a pilocytic astrocytoma to 12.4% in a glioblastoma multiforme. In the fibrillary astrocytic neoplasms of low cellularity, there were good correlations between the percentages of stained cells and the degrees of nuclear pleomorphism and chromatin density. In meningiomas, schwannomas, and a cerebellar hemangioblastoma, the fractions of labeled nuclei were less than 1%. The percentage of stained cells in pituitary adenomas showed considerable variation among the four cases (0.2-1.5%), the biologic significance of which is unknown. In four of the above cases, Ki-67 staining was performed on air-dried squash preparations with excellent visualization of immunoreactive nuclei. In one case, a hemangioblastoma, no stained nuclei were seen. The results confirm that Ki-67 staining is technically suitable as a diagnostic method, with good correlations between frozen sections and smear preparations. Determination of the replicating cell fraction could become an important additional criterion to predict the biologic behavior of nervous system neoplasms.

Adenoma↗
PubMed1986

Role of cyclic GMP of canine vascular smooth muscle in relaxation by organic nitrates.

The effects of organic nitrates on tone and tissue cyclic nucleotide levels were studied, using canine coronary, mesenteric and renal arteries, and femoral veins. Glyceryl trinitrate (GTN) relaxed all vascular tissues examined and increased tissue cyclic GMP (cGMP) levels in a concentration-dependent manner, but GTN induced no significant changes in cyclic AMP (cAMP) levels. An increase in cGMP levels induced by 10 microM of GTN in coronary arteries was observed before the onset of relaxation. Methylene blue, an inhibitor of guanylate cyclase, inhibited the relaxant effect of GTN and decreased cGMP levels. In contrast, M & B 22,948, an inhibitor of cGMP phosphodiesterase, not only enhanced relaxation by GTN, but also increased cGMP levels. Other organic nitrates, pentaerythritol tetranitrate (PETN), nicorandil (NIC), and isosorbide dinitrate (ISDN), also relaxed coronary arteries and increased cGMP levels in a concentration-dependent manner. A significant correlation was observed between percentage increases in cGMP levels and percentage relaxation by 10 microM of GTN, PETN, NIC, and ISDN (r = 0.952, p less than 0.001). Plasma concentrations of 4 organic nitrates inversely correlated with percentage increases in cGMP levels by 10 microM of these agents in coronary arteries (r = -0.845, p less than 0.001). These results suggest that an increase in cGMP is responsible for relaxation in vascular smooth muscles by organic nitrates, and that therapeutic plasma concentrations may be estimated by the degree of increase in cGMP levels induced by their administration.

Animals↗
PubMed1986

Clinico-pathological changes induced in rats treated with amine-curing agent for epoxy resin, bis(4-amino-3-methylcyclohexyl)methane.

Amine-curing agent for epoxy resin, bis(4-amino-3-methyl-cyclohexyl)methane (commercial name; Laromin C) has been suspected to have induced in the workers some toxic signs such as collagen disease like scleroderma or polymyositis. Subacute toxicity of this agent was studied in rats following repeated oral administration. The agent was given orally at 5 dose levels (25 mg/kg to 100 mg/kg per one dose) for periods ranging from 10 days to 4 weeks. After the completion of administration, clinico-biochemical tests and histopathological examinations were carried out. In a few cases, skeletal muscles and choroid plexus of the brain were examined by electronmicroscopy. Clinico-biochemical tests revealed some elevation of muscle-derived components such as GOT and CPK as seen in the myopathic diseases. Histologically, various degrees of atrophy, degeneration and regeneration of muscle fibers and a numerical increase of interstitial cells were observed in the skeletal muscles. Electronmicroscopical examination of the gastrocnemius muscle revealed intrasarcoplasmic osmiophilic round-shaped inclusion bodies, sometimes with lamellar structure, which were suggestive of some lipidosis. The epithelial cells of choroid plexus in the brain ventricles represented various degrees of vacuolar changes lightmicroscopically, which were suggested to be dilated smooth endoplasmic reticulum electronmicroscopically. Although scleroderma-like changes were not observed in our experiments, the results suggest that this amine-curing agent for epoxy resin could be one of the causative agents which induced toxic lesions like some collagen diseases including muscle lesions in the workers. In addition, it is considered that the agent may have systemic toxic effects.

Animals↗
PubMed1986

[Production of enzymes and enzyme inhibitors in neoplastic tissues].

The mechanisms of ectopic enzyme and enzyme inhibitor-production in neoplastic tissues were investigated. No evidence was obtained to suggest any difference in the structural genes of amylase-producing tumors and normal lymphocytes. mRNA sequence coding for amylase precursor in tumor tissues was identical to that of salivary amylase, suggesting that the amylase in amylase-producing tumors was identical to, or closely resembled the amylase in salivary gland. High incidence of elevation of serum pancreatic secretory trypsin inhibitor (PSTI) was observed in patients with various malignant tumors. PSTI-positive malignant cells were also frequently found in malignant tissues. A comparison of human PSTI mRNA sequence with mouse epidermal growth factor (EGF) mRNA sequence showed that they were 46% homologous. Human PSTI stimulated [3H]thymidine incorporation into DNA in human fibroblasts at concentrations present in human serum.

Amylases↗
PubMed1986

Mature T cells are part of adherent cells in human long-term bone marrow cultures.

We determined the proportion of lymphocytes in nonadherent and adherent fractions of human bone marrow cells cultured by a Dexter-type continuous marrow culture method. T-lymphocytes, B-lymphocytes, and common alloantigen (CALLA)-positive cells (cells with receptors for CALLA) were sequentially enumerated using commercially available appropriate monoclonal antibodies. Nonadherent cells from weeks 2-5 of culture contained relatively fixed proportions of OKT3-positive (4%-10.4%) and CALLA-positive (5%-6.6%) cells. The adherent cells during the culture period between weeks 6 and 18 contained an average of 34% OKT3-positive cells with a range from 6% to 68.5%, despite a high hydrocortisone concentration of 5 X 10(-5) M added to the growth medium. The T cells retrieved from the adherent layers and resuspended in steroid-free medium responded to PHA stimulation and to mixed leukocyte culture in the same manner as did freshly drawn peripheral blood leukocytes. These results indicate that adherent cell populations include mature T-lymphocytes in human long-term bone marrow cultures. In view of well-documented interactions of nonlymphoid hematopoietic progenitors with T-lymphocytes in the clonogenic culture system, it can be speculated that the adherent T cells also may play a role in proliferation and differentiation of granulocyte-macrophage and erythroid progenitors in this long-term culture system.

Antibodies, Monoclonal↗
PubMed1986

An in vitro and in vivo screening system for new hypoxic cell radiosensitizers using EMT6 cells.

An experimental tumor system consisting of single cells, spheroids, and solid tumors was developed using the EMT6/KU cell-line for evaluation of new hypoxic cell sensitizers. This paper describes the radiation dose-survival curves of the system and the effects of four sensitizers [misonidazole, Ro 03-8799, KB-11 (a sulfonyltetrazole derivative), and DNIE (a dinitroimidazole derivative)] in this system. Dose-survival curves of the spheroids varied significantly depending on the irradiation conditions, but it was found that the spheroids could model the solid tumors when they were irradiated in flat-bottomed flasks. These spheroids and solid tumors contained substantial fractions of hypoxic cells, and hence were suitable for testing hypoxic cell sensitizers. Misonidazole at a concentration of 1 mM or 1 mmol/kg showed a constant enhancement ratio (ER) of 1.55 in all of the systems. The ERs of the other three compounds for single cells, spheroids, and solid tumors were 2.1, 1.9, and 1.65, respectively, for Ro 03-8799 (1 mM or 1 mmol/kg); 2.6, 1.6, and 1.0, respectively, for KB-11 (0.5mM or 0.5 mmol/kg); 1.8, 1.2, and 1.1, respectively, for DNIE (0.5mM or 0.5 mmol/kg). These results indicated that the ER for spheroids is closer to the ER for solid tumors than is the ER for single cells in most cases. It was also suggested that an efficient sensitizer in vivo shows little or no difference between its ER for single cells and that for spheroids.

Animals↗
PubMed1986

Specific binding of human pancreatic secretory trypsin inhibitor to various cultured cells.

Pancreatic secretory trypsin inhibitor from human pancreatic juice bound specifically to cultured cells derived from a variety of human and nonhuman tissues. The binding pattern of pancreatic secretory trypsin inhibitor to various cells was quite different from that of epidermal growth factor, and these two polypeptides did not compete in binding to cultured cells with one another, indicating that the binding site for pancreatic secretory trypsin inhibitor was distinct from the receptor for epidermal growth factor.

Animals↗