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Biomedical subjects

T Oka

Publications and source records attributed to T Oka.

At least 1,225 records · Page 68Linked to original sources
PubMed1984

Effects of irradiation of skin flaps.

The reaction of skin flaps to irradiation and the optimum postoperative time for irradiation was studied in the rat. Flaps showed different reactions depending on the time of irradiation. There was a correlation between the radiosensitivity and the vascularity of the flap. Those flaps in the marginal hypovascular stage of revascularization showed reactions similar to normal skin. However, severe adverse reactions were observed in the marginal hypervascular stage.

Angiography↗
PubMed1984

Experimental study of dermal grafts for reconstruction of oral mucosa.

Mucosal defects in the oral cavities of 35 dogs were repaired with reversed dermal grafts, full-thickness skin grafts, and dermal grafts. Comparative observations were made for up to two years to analyze the healing processes. The reversed dermal grafts were covered by surrounding mucosal epithelium and formed normal mucosal tissue that maintained its characteristics for two years. Histologic and scanning electron microscopic examination revealed that the epithelial appendages underwent degeneration, presumably through being embedded by the grafting of the dermis inside out. Epithelialization of the dermal grafts occurred from both surrounding mucosal epithelium and ancillary skin appendages. The full-thickness skin grafts maintained their original structure and function over the two-year observation period. It appears from this investigation that the reversed dermal graft method has definite advantages over full-thickness skin grafting and dermal grafting.

Animals↗
PubMed1984

A risk of inaccuracy in biochemical analysis of urinary stone-forming salts.

We investigated the occasional inaccuracy in the biochemical measurement of urine by comparing the values from untreated samples to those obtained following our experimental pre-treatment regimen, which prevents precipitation and dissolves visible crystals. Discrepancies were observed between some of the paired samples, especially with regard to calcium and uric acid (urate) concentrations. Moreover, considerable differences were recognized in fresh as well as stored urine specimens. Our findings demonstrate the need to develop accurate methods of processing urine for biochemical analysis with multichannel autoanalyzers.

Autoanalysis↗
PubMed1984

Dynamic vascular changes in free skin grafts.

Vascular changes in full-thickness skin grafts in rats were examined at various intervals after grafting using microangiography. The grafted skin and its bed showed dynamic vascular changes that were considered to be related to release of an " angiogenetic factor" produced by the skin under oxygen-deficient conditions such as ischemia. The first filling of contrast medium in the grafts was observed 24 hours after grafting. Both primary and secondary revascularization were observed.

Angiography↗
PubMed1984

Liposarcoma of the cheek in an infant.

A case of liposarcoma of the cheek in a 6-month-old infant has been presented. This tumor, one of the most common malignant tumors of soft tissue in the body generally, is exceedingly rare in the head and neck regions, having been reported in this location on only a few occasions. A review of the literature reveals that this patient was one of the youngest so affected. The postoperative course was uneventful, and after three years no evidence of recurrence or metastasis has been observed.

Cheek↗
PubMed1984

Clinical experience with a protease inhibitor [N,N-dimethylcarbamoylmethyl 4-(4-guanidinobenzoyloxy)-phenylacetate] methanesulfate for prevention of recurrence of carcinoma of the mouth and in treatment of terminal carcinoma.

A protease inhibitor, (N,N-dimethylcarbamoylmethyl 4-(4-guanidinobenzoyloxy)-phenylacetate) methanesulfate was administered orally 3 times daily to 9 patients with squamous cell carcinoma of the oral cavity, at doses ranging from 0.6 g. to 7.2 g. Seven of 9 patients who had undergone all kinds of therapies were observed to see whether recurrence was prevented and in no case did the tumour recur. Also, in 2 terminal secondary cases tumour remission resulted. Histologically, after this therapy, carcinomatous lesions showed marked hyperkeratosis in 2 cases and the survival time in 1 case was markedly prolonged. Haematological and gastrointestinal toxicity was almost never observed at these doses.

Adult↗
PubMed1984

Evidence for physiological function of epidermal growth factor: pregestational sialoadenectomy of mice decreases milk production and increases offspring mortality during lactation period.

Female virgin mice, whose submandibular glands were removed, underwent normal pregnancy and delivery. During the nursing period, however, a substantial number of pups born to and nursed by sialoadenectomized mothers died within 5 days of birth, whereas this did not occur among pups born to normal mothers. Cross-foster nursing experiments indicated that the cause of death of pups was to be found in sialoadenectomized mothers, not in the pups. The capacity of the sialoadenectomized mothers to nurse pups was much less than that of normal mothers, as shown by experiments involving alterations in the number of pups nursed by both sialoadenectomized and normal mothers. The mammary gland of lactating sialoadenectomized mice was smaller in size and produced less milk compared with that of normal mice. No apparent qualitative difference in milk proteins was found in the milk produced by the two groups of mothers. The decreased growth of the mammary gland of sialoadenectomized mice was also manifested during the second half of pregnancy, and mammary explants from those mice synthesized less casein in response to lactogenic stimuli, insulin, cortisol, and prolactin, in an organ culture system, when compared with mammary explants from normal pregnant mice. When epidermal growth factor, a polypeptide hormone that is synthesized and secreted by the submandibular gland, was injected daily at a dose of 5 micrograms into sialoadenectomized pregnant mice, the survival rate of the pups nursed by their mothers increased to the value obtained with normal mothers. The results were discussed in terms of a possible role of the submandibular gland and epidermal growth factor in the development of the mammary gland.

Animals↗
PubMed1984

Efficient expression in Escherichia coli of a mature and a modified human interferon-beta 1.

Ten recombinant plasmids were constructed which direct the synthesis of a mature human interferon-beta 1 (IFN-beta 1) under the control of the Escherichia coli tryptophan (trp) promoter. The spacing between the Shine-Dalgarno sequence of the trpL and the ATG initiation codon of the interferon gene was varied from 6 to 23 nucleotides by utilizing a Cla I site located within the spacer region of the plasmids. The optimal spacing for expression of IFN-beta 1 was determined to be 8-13 nucleotides from the results of interferon assay. The E. coli lipoprotein (lpp) promoter was also used for expression of IFN-beta 1 in E. coli. The results with an expression vector carrying a lpp-lac promoter showed that a modified IFN-beta 1 containing an additional 7 amino acids at the amino-terminus might be less active than the mature molecule.

Amino Acid Sequence↗
PubMed1984

Protoplast transformation of glutamate-producing bacteria with plasmid DNA.

A method for polyethylene glycol-induced protoplast transformation of glutamate-producing bacteria with plasmid DNA was established. Protoplasts were prepared from cells grown in the presence of penicillin by treatment with lysozyme in a hypertonic medium. The concentration of penicillin during growth affected the efficiency of formation, regeneration, and polyethylene glycol-induced DNA uptake of protoplasts. Regeneration of protoplasts was accomplished on a hypertonic agar medium containing sodium succinate and yeast extract. The spectinomycin and streptomycin resistance plasmid pCG4, originally from Corynebacterium glutamicum T250, could transform various glutamate-producing bacteria such as C. glutamicum, Corynebacterium herculis, Brevibacterium flavum, and Microbacterium ammoniaphilum. The plasmid was structurally unchanged and stably maintained in new hosts. The transformation frequency of most competent protoplasts with pCG4 DNA isolated from primary transformants was high (ca. 10(6) transformants per microgram of covalently closed circular DNA) but was still two orders of magnitude below the frequency of transfection with modified DNA of the bacteriophage phi CGI. The difference was ascribed to the involvement of regeneration in transformation.

Brevibacterium↗
PubMed1984

Regulation of opioid antagonist and mu, kappa or delta agonist binding by guanine nucleotide and sodium.

Effects of 5'-guanylylimidodiphosphate (Gpp(NH)p) and sodium on the inhibition by various opioids of [3H]-naloxone binding to guinea-pig brain membrane preparations were studied. The ratio of the concentration required to produce a 50% inhibition of [3H]-naloxone binding in the presence of both Gpp(NH)p and sodium to that in the absence of both Gpp(NH)p and sodium (IC50 ratio) was less than 1 for antagonists, from 3 to 10 for mixed agonist-antagonists, from 16 to 85 for either kappa, delta, or peptide mu agonists, and more than 200 for morphine-like nonpeptide mu agonists. Exceptionally, the IC50 ratio of N,N-diallyl-[D-Ala2,D-Leu5]-enkephalin, an opioid which had been shown not to have an agonist activity in guinea-pig ileum but to have a naloxone-reversible agonist activity in mouse vas deferens, was less than 1. The significance of the different IC50 ratio among opioids employed in the present study was discussed.

Animals↗
PubMed1984

Two new opioid delta-receptor ligands: a highly selective agonist and a potent selective antagonist in in vitro isolated preparations.

N,N-Diallyl derivatives of enkephalin analogues were chemically synthesized, and their biological activities were estimated in vitro isolated preparations. N,N-Diallyl-[D-Ala2, D-Leu5]-enkephalin [test compound I] at doses up to 10 microM did not inhibit the electrically-evoked contractions of guinea-pig ileum, which had been suggested to contain opioid mu- and kappa-receptors, but it significantly depressed the contractions of mouse vas deferens, which had been indicated to contain mu-, kappa- and delta-receptors, suggesting that test compound I did not act on both mu- and kappa-receptors, but acted on delta-receptors. Additionally, the Ke (equilibrium dissociation constant) values against test compound I of naloxone were approximately 30 nM and similar to those of Mr 2266, also indicating that test compound I acted as a delta agonist. Moreover, the Ke values of ICI 154129 against compound I were approximately 340 nM, strongly suggesting that test compound I acted as a delta agonist. The Ke values of bis-[N,N-diallyl-[D-Ala2, Leu5]-enkephalyl]-cystine [test compound II] against [D-Ala2, D-Leu5]-enkephalin in mouse vas deferens and morphine or ethylketocyclazocine in guinea-pig ileum were 44.9 nM and 5.00 or 11.3 microM, respectively, showing that test compound II was a potent selective opioid delta antagonist. In conclusion, among compounds synthesized, two new opioid delta-receptor ligands, one being a highly selective agonist and the other being a potent selective antagonist in in vitro isolated preparations, were found in the present study.

Animals↗
PubMed1984

The role of bestatin-sensitive aminopeptidase, angiotensin converting enzyme and thiorphan-sensitive "enkephalinase" in the potency of enkephalins in the guinea-pig ileum.

The role of each enkephalin-hydrolyzing peptidase in the inhibitory potency of exogenously added enkephalins in the myenteric plexus-longitudinal muscle preparation of guinea-pig ileum was studied by using the relatively specific inhibitor of each enzyme. Results showed that three distinct enzymes, bestatin-sensitive aminopeptidase(s), angiotensin converting enzyme, and thiorphan-sensitive "enkephalinase", played a critical role in the inactivation of enkephalins. Additionally, these enzymes are likely to be located close to opioid receptors, since they produce a significant concentration difference of enkephalin between the surrounding organ bath and the vicinity of opioid receptors. In contrast to these three enzymes, both L-tyrosyl-L-tyrosine-sensitive dipeptidyl aminopeptidase and D-phenylalanine-sensitive carboxypeptidase are indicated not to be involved significantly in the degradation of exogenously added enkephalins in the guinea-pig ileum.

Amino Acids, Sulfur↗
PubMed1984

The effects of morphine, naloxone and capsaicin on C-fiber reflex and heat evoked discharge in acute spinal cats.

The electrophysiological effects of morphine, naloxone and capsaicin were studied on c fiber reflex and heat evoked discharge in adult spinal cats. C fiber reflex was recorded from the L7 Ventral root at the time of superficial peroneal nerve electric stimulation. Heat evoked discharge was recorded from the L7 ventral root at the time of hind paw heating. The drugs were injected slowly into the right cephalic vein. Our results can be summarized as follows: morphine depressed the excitatory neuronal activity of capsaicin; morphine followed by capsaicin was antagonized by 0.4 mg/Kg of naloxone; at the c fiber reflex, 2 mg/Kg of morphine depressed the neuronal activity; and at heat evoked discharge, 4 mg/Kg of morphine depressed the neuronal activity. These findings suggest that morphine depressed the effect of capsaicin and this effect was antagonized by naloxone. At the c fiber reflex, morphine was more sensitive than at heat evoked discharge.

Animals↗
PubMed1984

Evaluation of varicella vaccine in childhood leukemia. Observation over 6 years.

Since 1977, we have used a live attenuated varicella vaccine to immunize 10 children with acute leukemia. 8 patients had no adverse clinical reaction but 2 patients developed mild fever and papulovesicular rash after vaccination. All 9 tested children became seropositive after the vaccination. Also in all 3 children who were observed for more than 4 years, persistence of neutralizing antibody was detected. Most of the recipients were prevented from developing symptoms of varicella in spite of contact exposure. Two patients developed varicella when they were in severe immunosuppressive states but their symptoms were mild. None of the children developed herpes-zoster during the 6 year follow-up period. The results suggest that the varicella vaccine is effective in children with acute leukemia, and that long-term effectiveness can be expected.

Antibodies, Viral↗