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Biomedical subjects

T Oka

Publications and source records attributed to T Oka.

At least 1,243 records · Page 69Linked to original sources
PubMed1984

Proliferation stimulating effects of chrysotile and crocidolite asbestos fibres on B lymphocyte cell lines.

Asbestos fibres of chrysotile, crocidolite and amosite were incubated with eight types of human cell lines in vitro. These asbestos fibre were cytotoxic to fibroblasts and monocyte like cells, as is already known. On the other hand, immature B lymphocyte lines (B1 2) were stimulated significantly by chrysotile and crocidolite, while a mature B cell line (B3) was not affected. Cell proliferation of a T cell line and an erythromyeloid cell line also was not affected by asbestos. For the stimulation of lymphocytes, the binding of the mitogen to the reactive sites on the lymphocyte surface is thought to be indispensable. It seems that chrysotile and crocidolite asbestos can bind to immature B lymphocytes, but not to mature B cells.

Asbestos↗
PubMed1984

Postoperative irradiation after reconstructive surgery: comparative study of radiosensitivity between free-skin grafts and skin flaps.

Radiation effects after reconstructive surgery (free-skin grafts and skin flaps) were studied in the rat, and the optimum time for irradiation was determined. The radiosensitivity of both free-skin grafts and skin flaps showed the same trend depending on time of irradiation after operation. The grafts or flaps irradiated in the hypervascular stage showed severe reactions to irradiation, whereas those irradiated in the hypovascular stage showed milder reactions in gross and microangiographic observation. Vascular damage should be given primary consideration when deciding the proper time for irradiation after reconstructive surgery. In general, free-skin grafts showed more severe reactions than skin flaps, especially in the grafts irradiated in the early stage after operation. The experimental results of this study cannot be readily transferred to a clinical setting, but they suggest that postoperative irradiation could be begun 3 to 4 weeks after operation with respect to graft or flap survival, and the results of the clinical cases almost coincide with these experimental results.

Angiography↗
PubMed1984

[A child with successfully treated posterior mediastinal endodermal sinus tumor].

A 15-month-old boy with posterior mediastinal endodermal sinus tumor is reported. The patient was admitted with recurrent hemothorax, and his serum alpha-fetoprotein level was 29,520 ng/ml. After removal of the posterior mediastinal tumor, VAC therapy (vincristine, actinomycin D, cyclophosphamide) was started. The chemotherapy was continued 18 months. The patient continues to do well with no sign of tumor and a normal alpha-fetoprotein level 53 months after the operation and 35 months after the completion of therapy. He is the youngest patient documented in the literature and successfully treated for mediastinal endodermal sinus tumor.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1984

A case of colon cancer metastasizing to the spleen.

A case of colon cancer metastasizing to the spleen is reported. The patient was a 43-year-old man who was laparotomized under the diagnosis of colon cancer. The tumor of the transverse colon showed a small ulcer and polypoid projections. Poorly differentiated adenocarcinoma was noted in the mucosa. Marked tumor metastasis was found in the parenchyma of the spleen and the peripancreatic, portohepatic, mesenteric and periaortic lymph nodes. The literature on the incidence and mechanism of metastasis to the spleen was reviewed, and metastasis to the spleen was found to be not infrequent at a late or advanced stage of cancer.

Adult↗
PubMed1984

[Pharmacokinetic and clinical studies of latamoxef (moxalactam) in neonates and premature infants].

Studies were carried out on the in vivo kinetics and clinical efficacy of latamoxef (LMOX) in neonates and premature infants. The results are summarized below. Serum concentration and T1/2 following intravenous injection of LMOX to neonates LMOX was intravenously administered to neonates as one shot doses of 10 mg/kg and 20 mg/kg. The serum concentration of LMOX showed a dose-response to the 10 and 20 mg/kg doses in each of the 0--3 day-old group, 4--7 day-old group and 8--28 day-old group. The T 1/2 values were as follows; for the 10 mg/kg dose, 5.17 hours in the 0--3 day-old group, 3.28 hours in the 4--7 day-old group and 2.79 hours in the 8--28 day-old group; for the 20 mg/kg dose, 5.58 hours in the 0--3 day-old group, 3.46 hours in the 4--7 day-old group and 3.14 hours in the 8--28 day-old group. Thus, it is seen that the half-life of both dosages decreased as the infants became older. Serum concentration and T 1/2 following intravenous injection of LMOX to premature infants Similar to the case of neonates described above, the concentration of LMOX in the serum of the premature infants showed a dose-response to the 10 mg/kg and 20 mg/kg dosages. The T 1/2 values for the 0--3, 4--7 day-old and 8--28 day-old groups were 7.54, 3.93 hours and 6.25 hours, respectively, for the 10 mg/kg dose, and 10.8, 4.05 hours and 3.23 hours, respectively, for the 20 mg/kg dose. Again, it is seen that the half-life of both dosages decreased as the age of the prematurely-born infants increased. Serum concentration and T1/2 following 1-hour intravenous drip infusion of LMOX to neonates LMOX was administered to neonates in doses of 10 mg/kg and 20 mg/kg, by i.v. drip infusion over a 1-hour period. With both dosages, the peak serum concentration of LMOX occurred at the time of completion of the infusion. The T1/2 values for the 0--3, 4--7 day-old and 8--28 day-old groups were 5.41, 3.68 hours and 1.92 hours, respectively, for the 10 mg/kg dose, and 5.31, 2.67 hours and 4.86 hours, respectively, for the 20 mg/kg dose. Urinary excretion of LMOX in neonates and premature infants. The percentage of the administered LMOX dose contained in the urine excreted during the 6-hour period following intravenous administration of LMOX to neonates and premature infants was determined.(ABSTRACT TRUNCATED AT 400 WORDS)

Humans↗
PubMed1984

Villous tumor of the stomach associated with adenocarcinomas--a histochemical study of mucosubstances.

A case is described in which both a moderately elevated villous adenoma associated with adenocarcinoma at the posterior wall and an independent gastric carcinoma at the anterior wall were present. These two lesions were surrounded by the mucosa of incomplete intestinal metaplasia. Consecutive sections of the villous adenoma associated focally with carcinoma and the independent cancer were stained by the periodic acid-Schiff (PAS), pH 2.5 alcian blue (A1-B1), high iron diamine pH 2.5 alcian blue (HID-AB) and carcinoembryonic antigen peroxidase-antiperoxidase (CEA-PAP) methods. Villous adenoma was weakly positive in the PAS stain but negative in A1-B1 and HID stains, showing that it did not produce mucin. On the other hand, the intestinal metaplasia and cancerous lesions were positive in PAS, A1-B1 and HID stains, indicating production of the intestinal type of mucin. The villous adenoma accompanied by malignant changes was positive by the CEA-PAP method. This result shows the biological property of villous adenoma that they can easily change into malignancy. These three lesions in our case are considered to have originated independently from the primordial cells and to have developed the differences in mucin production in the process of cell development.

Adenocarcinoma↗
PubMed1984

The effect of naloxone on C-fiber reflex in cats.

The specific opiate antagonist naloxone rapidly reverses hypotension caused by endotoxin, hypovolemia and spinal transection. The fact that naloxone appears to act as a causative level to improve shock pathophysiology, as well as its extensive clinical use for opiate overdose, makes this drug a particularly clinical use for opiate overdose, makes this drug a particularly attractive potential therapeutic agent for the treatment of shock in humans. The electrophysiological effects of naloxone were studied on c-fiber reflex in spinal and intact cats. The drugs were injected in to the right cephalic vein. Results can be summarized as follows: Naloxone in the intact cat had a more pronounced facilitating effect than in the spinal cat. Naloxone given as a one shot injection was more potentiating than naloxone given as a 5 minute injection. Naloxone antagonized the facilitation of a small dose of ketamine-HCL in the intact cat and also the depression of a large dose ketamine-HCL. Naloxone antagonized capsaicin on c-fiber reflex. This result supports that naloxone has the antagonizable inhibitory effect of substance-P. Naloxone for the first injection had an effective response but additional naloxone did not facilitate the c-fiber reflex.

Animals↗
PubMed1984

Pharmacokinetics and the antiarrhythmic effect of mexiletine in patients with chronic ventricular arrhythmias.

A new antiarrhythmic agent, 1-(2,6- dimethylphenoxy )-2-aminopropane (mexiletine), was investigated in 10 patients with chronic premature ventricular contractions (PVCs) to evaluate the antiarrhythmic efficacy and the pharmacokinetics after single intravenous, single oral and repeated oral dosings of mexiletine 150 mg. Mexiletine was well absorbed from the intestinal tract. The relative bioavailability was 83.2 +/- 8.9% (mean +/- S.E.). The time-concentration curve of mexiletine fitted in well with two-compartment open model. Elimination half-life, volume of distribution and plasma clearance were 10.54 +/- 0.26 h, 2.10 +/- 0.49 l/kg, 6.01 +/- 0.63 ml/min/kg, respectively. The computer-simulated time-concentration curves of multiple oral dosings , which were based on the kinetic parameters from single oral dosing, conformed well with measured concentrations. This might be applied to predict the plasma level of mexiletine. The steady state of plasma mexiletine level was reached 4-5 days after 450 mg/day dosings and ranged 0.75-2.18 micrograms/ml. In 6 of 10 patients, the frequency of PVCs was suppressed more than 75% as compared with the pre-medication value. Mexiletine was well tolerated at a dose of 450 mg/day. However, of 4 patients with the dose increased to 600 mg/day, the administration was ceased in three patients due to gastrointestinal symptoms and tremor. All of these adverse reactions disappeared when the administration was stopped. These results suggest that mexiletine is effective against ventricular arrhythmias and the dosage should be carefully adjusted. The prediction of plasma level would be applied to the dosage regimen of mexiletine.

Adult↗
PubMed1983

5'-Terminal sequence of the mRNA of mouse whey acidic protein contains three possible sites of interaction with 18S rRNA.

The mRNA sequence of whey acidic protein, a major mouse milk protein, was cloned in full length. The sequence analysis of the cDNA clones revealed that the mRNA contains a 28 nucleotide-long 5'-noncoding region. Three different portions of this region were identified as possible sites of interaction with the 3'-end of 18S rRNA that may facilitate efficient rate of translation of the mRNA.

Animals↗
PubMed1983

The study of spermidine-stimulated polypeptide synthesis in cell-free translation of mRNA from lactating mouse mammary gland.

The stimulatory effect of spermidine on the translation of poly(A)+ mRNA from lactating mouse mammary glands in a wheat germ system was studied. Spermidine stimulated total polypeptide synthesis about 2.5-fold relative to that occurring in the presence of an optimal concentration of Mg2+ alone. The size and the number of polysomes were about 1.6-times larger in the presence of spermidine than in its absence. A similar magnitude of increase in peptide chain initiation, 1.4-fold, was found when the extent of peptide chain initiation was measured by determining the residual polypeptide synthesis subsequent to the addition of inhibitor(s) of peptide chain initiation to the in vitro translation system with or without spermidine at various times of the incubation. Time-course study of the release of polypeptide from polysomes showed that spermidine stimulated this process to a much greater extent than peptide chain initiation, indicating that the polyamine also increases the rate of peptide chain elongation. The extent of stimulation of peptide chain elongation by spermidine was estimated to be about 1.5-fold when the disappearance of isotope-labeled nascent peptides from polysomes was measured by pulse-chase experiments. These results indicate that spermidine stimulates the cell-free translation of mammary mRNA by increasing the rates of both initiation and elongation of polypeptide synthesis to almost the same extent. The polyamine also reduced the relative amount of incomplete polypeptides, thereby increasing the yield of full-length translational products.

Animals↗