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Biomedical subjects

K Takada

Publications and source records attributed to K Takada.

At least 901 records · Page 50Linked to original sources
PubMed1982

[Clinical results of FAR (5-FU, vitamin A, and radiation) therapy in head and neck cancer].

Combination therapy of 5-FU, vitamin A and radiation (FAR therapy) was given to 50 patients with squamous cell carcinoma of the head and neck. The primary effect was observed in 22 patients who received FAR therapy as radical therapy. Among them, only 4 patients had recurrence or metastasis, and death was none. FAR therapy was given to 4 patients as pre-operative therapy and to 2 patients as post-operative therapy. However, the number of cases was not enough for us to draw any conclusion. In the group of 22 patients consisting of patients with recurrence or metastasis and patients who refused operation or were unresectable, no primary effect was observed only in 4 patients. Among a total of 50 patients, only 4 patients did not show a primary response to FAR therapy, 19 had relapse, 19 died (6 cases of them died from other causes), and 31 are still alive. There were no patients having severe side effects. From these results, FAR therapy seemed to be worth trying in treatment of head and neck cancer.

Adult↗
PubMed1982

Discriminative stimulus effects of pentobarbital in rats.

The discriminative stimulus effects of a low dose of sodium pentobarbital (4 mg/kg, sc) were investigated in 10 rats trained to discriminate between the drug and saline under a 2-lever choice procedure. A food pellet was delivered after every 10 depressions of the appropriate lever, which lever was appropriate being determined by whether the drug or saline was administered prior to the daily session. Discrimination of the substances was said to have been attained when more than 8 out of the 1st 10 responses were to the appropriate lever for 10 consecutive days, and 7 rats met the criterion after 43 to 96 sessions. Stimulus generalization tests revealed the stimulus properties of the drug at 4 mg/kg to be similar to those of diazepam 0.25 mg/kg, sc and ethanol 1 g/kg, ig, but not of various doses of d-amphetamine, morphine, pentazocine, chlorpromazine, and imipramine. It was thus found that the rats could discriminate a relatively low dose of pentobarbital and that its stimulus effects do not differ from those at higher doses reported by other investigators.

Animals↗
PubMed1981

Application of high-performance liquid chromatography to the study of esterified 7-dehydrocholesterol in rat skin.

A novel and precise method for determining free and esterified 7-dehydrocholesterol in rat skin was developed by using a two-step high-performance liquid chromatography system. This method involves initial lipid extraction, separation of the free and esterified 7-dehydrocholesterol by, firstly, preparative high-performance liquid chromatography, saponification, and determination by, secondly, analytical high-performance liquid chromatography. This method was applied to the study of the 7-dehydrocholesterol in rat skin. Almost all of the 7-dehydrocholesterol in rat skin was present in an esterified form (78-93%). Ultraviolet exposure of the skin increased total 7-dehydrocholesterol content, however, the percentage of esterified 7-dehydrocholesterol was not altered appreciably. Application of this method to the study of the photo-metabolism of 7-dehydrocholesterol in rat skin revealed that almost all of the vitamin D3 produced by ultraviolet rays was in the esterified form.

Animals↗
PubMed1981

Isolation and identification of tachysterol3 in rat skin exposed to ultraviolet light.

In order to investigate the mechanism of the cutaneous synthesis of vitamin D3 in vivo, a photolysis by-product of previtamin D3 in organic solvent, namely, tachysterol3 was isolated and identified in ultraviolet-exposed rat skin. Tachysterol3 was identified by chromatographic comigration of an ultraviolet-absorbing peak wih authentic tachysterol3 in straight-phase HPLC (Zorbax SIL column) and reversed-phase HPLC (Nucleosil 5C18 column), and by the ultraviolet absorption spectrum. The comparison of the extent of formation of tachysterol3 between in rat skin in vivo and in ethanol solution indicated that the yield in rat skin is similar to that in organic solvent. The results suggest that the reaction mechanism in rat skin in vivo may be identical wit that in organic solvents.

Animals↗
PubMed1981

Analysis of the transformation of human lymphocytes by Epstein-Barr virus III. Induction of early events by P3HR-1 strain without subsequent immortalization.

T-cell depleted human cord blood lymphocytes were exposed to P3HR-1 strain of Epstein-Barr virus (EBV) and simultaneous observations of immunofluorescence, cellular morphology, and autoradiography were carried out in individual cells. Soon after infection, nuclear antigen (EBNA) synthesis, blastogenesis, and DNA synthesis occurred, as was previously observed B95-8 strain EBV infection. Although mitosis followed with characteristic cell aggregate formation, the cell proliferation was temporary and death followed in about 2 weeks. The synthesis of the early antigens (EA) and the viral capsid antigen (VCA) were not significant. These findings seem to indicate that the strain P3HR-1 EBV is capable of inducing early events of transformation in primary human B-lymphocytes, but the cells infected in this way have a short life span.

Antigens, Viral↗
PubMed1981

A new fluorogenic peptide substrate for vitamin K-dependent blood coagulation factor, bovine protein C.

Protein C is a precursor of plasma serine proteinases, and its active form inactivates specifically blood coagulation Factor V and Factor VIII. Since a specific and sensitive synthetic substrate for the activated protein C was not known, we studied its amidolytic activity toward 25 fluorogenic peptides of the type peptidyl-4-methylcoumaryl-7-amide (peptidyl MCA). The activated protein C, namely, bovine protein C activated by bovine alpha-thrombin, showed the highest activity toward Boc-Leu-Ser-Thr-Arg-MCA. The enzyme's Km and Kcat values for this substrate were calculated to be 3.3 x 10(-4) M and 8.4 s-1, respectively. Optimum conditions for measurement of activated protein C activity were studied with this substrate. Optimum pH was 8.5. For the maximum activity at pH 8.5, concentrations of 0.1 M NaCl and 1 mM CaCl2 had to be maintained in the reaction mixture. The fluorogenic peptide Boc-Leu-Ser-Thr-Arg-MCA was successfully applied to a simple and accurate assay of protein C during its purification.

Animals↗
PubMed1981

Epstein-Barr virus susceptibility of B cells correlates to the presence of complement receptors but not surface immunoglobulins.

Nuclear antigen (EBNA) inducibility by Epstein-Barr virus (EBV) was assessed in relation to the presence of complement (C3) receptors and surface immunoglobulins (SIg) on leukemic lymphocytes. When erythrocyte-antibody-complement complex(EAC)-positive, SIg-negative B cells were exposed to EBV, EBNA synthesis occurred with a high frequency. In contrast, no significant EBNA induction was evident in SIg-positive, EAC-negative B cells. Cells possessing both markers were EBV-infectable, in proportion to the frequency of EAC-rosette formation. These data seem to indicate that EBV susceptibility of human B cells is closely related to the presence of C3 receptors but not SIg. Leukemic T cells and myelogenous leukemia cells were not EBV-susceptible, although some cells were significantly positive for C3 receptors.

Antigens, Viral↗