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Biomedical subjects

T Oka

Publications and source records attributed to T Oka.

At least 1,117 records · Page 62Linked to original sources
PubMed1987

[A successful cross-over femorotibial bypass for severe ischemic leg of thromboangiitis obliterans].

A case of thromboangiitis obliterans (TAO) successfully treated with a modified vascular reconstruction is reported. A 53 year-old man who had undergone lumber sympathectomy 9 years ago visited our hospital with complaints of rest pain and intractable ulcer at the right big toe. Preoperative angiography could not visualize distal arteries from the right common iliac artery and major amputation above knee was intended. Operative angiography, however, revealed collateral pathways from the posterior tibial artery to plantar arteries. Then, a long bypass from the left common femoral artery to the right posterior tibial artery was made using saphenous vein grafts of both extremities, 75 cm in length. Postoperatively, a solution containing urokinase, PGE1 and heparin was infused continuously for two months through a tube inserted into a branch of the graft. The pain disappeared and the ulcer healed. Now one year after the operation, the bypass graft is patent and the patient is fully rehabilitated. This experience indicates that some of ischemic legs with poor run off due to TAO can be salvaged by such modified vascular reconstruction and postoperative local PGE1 infusion therapy.

Alprostadil↗
PubMed1986

A physiological role of epidermal growth factor in male reproductive function.

Epidermal growth factor (EGF) stimulates the proliferation of various mammalian cells in culture, but its physiological role is not well defined. In mature male mice, large amounts of EGF are produced in the submandibular gland; it is present in the circulation at approximately 5 nanograms of EGF per milliliter of plasma. Sialoadenectomy (removal of the submandibular glands) decreased the amount of circulating EGF to an undetectable level but did not affect the circulating levels of testosterone or follicle-stimulating hormone. The number of mature sperm in the epididymis decreased by as much as 55 percent; the number of spermatids in the testis decreased by 40 to 50 percent; and the number of spermatocytes increased by about 20 percent. Administration of EGF to sialoadenectomized mice restored both the sperm content of the epididymis and the number of spermatids in the testis to normal. Thus, EGF may play a role in male reproductive function by stimulating the meiotic phase of spermatogenesis.

Animals↗
PubMed1986

Involvement of the Ca2+-dependent K+ channel activity in the hyperpolarizing response induced by epidermal growth factor in mammary epithelial cells.

Epidermal growth factor (EGF) induces a hyperpolarizing response of 5-20 mV amplitude in mouse mammary epithelial cells in culture. The amplitude of the hyperpolarizing response was reduced by more than 60% within several minutes after addition of blockers of voltage and/or Ca2+-dependent K+ channels such as tetraethylammonium (7 mM) or quinine (0.29 mM). Both nifedipine (0.15 mM), a blocker of the Ca2+ channel, and ruthenium red (2 mM), an inhibitor of the Ca2+-binding site, also reduced the amplitude of the hyperpolarizing response by more than 60%. The Ca2+ ionophore, A23187 (3.8 microM), induced a large hyperpolarization, which was 25-40 mV and lasted about 3 min. These data suggest that activity of the Ca2+-dependent K+ channel was involved in the EGF-induced hyperpolarizing response of the mammary epithelial cells.

Animals↗
PubMed1986

Transformation of hamster spleen lymphocytes by human T-cell leukemia virus type I.

Co-cultivation of spleen cells of Syrian golden hamsters with lethally irradiated MT-2 cells harboring human T-cell leukemia virus type I (HTLV-I) resulted in the establishment of lymphoid cell lines, HCT-1 and HCT-2, which exhibited the normal karyotype of golden hamsters. Cells of both the HCT-1 and HCT-2 lines lacked surface immunoglobulins and reacted with a monoclonal antibody (MAb) specific for hamster T cells. Some were positive for OKIa1. None of them expressed HTLV structural antigens (p19 and p24) or virus particles, but they contained HTLV-I proviral DNA monoclonally. By immunochemical analysis of the labelled cell antigens, sera from adult T-cell leukemia (ATL) patients reacted with the two polypeptides, p37 and p40, which may not be viral structural proteins and still remain to be characterized. HCT-1 and HCT-2 cells were transplantable into newborn hamsters, pre-treated with anti-hamster thymocyte serum and non-treated, respectively, producing diffuse malignant lymphoma. These findings indicated that HTLV-I not only immortalized but also transformed hamster T cells non-productively.

Animals↗
PubMed1986

Developmental regulation of glycosyltransferases involved in biosynthesis of asparagine-linked glycoproteins in mouse mammary gland.

Three glycosyltransferases, namely N-acetylglucosaminyl-1-phosphotransferase, mannosyltransferase and glucosyltransferase, involved in the biosynthesis of asparagine-linked glycoproteins in the mouse mammary gland, were identified by characterization of the products formed by these enzymes. The tissue capacities of the glycosyltransferases, measured as pmol product formed g tissue-1 min-1, increase during developmental cycle of the gland until, at late lactational stage, they reach more than 34, 14 and 60 times, respectively, the basal level found in the tissue of virgin animals. Among the three enzymes at late lactational stage the specific activities of glucosyltransferase and N-acetylglucosaminyl-1-phosphotransferase increase 7-fold and 4-fold respectively, whereas mannosyltransferase shows a mere 1.4-fold increase during tissue development. All of the enzymes, both in terms of tissue capacity and specific activity, return to the basal levels of the virgin gland one month after the end of lactation. The activities of the three enzymes in the lactating gland decrease precipitously following treatment of mice with bromocriptine, a drug that interferes with the release of prolactin from the pituitary gland and thereby inhibits milk synthesis and secretion. These results indicate that the three glycosyltransferases are developmentally regulated during the growth and differentiation of the mouse mammary gland.

Animals↗
PubMed1986

Improved outcome of renal transplantation with cyclosporine compared with azathioprine--experience in 33 recipients followed for over one year.

Long-term clinical aspects after kidney transplantation using cyclosporine (CsA) were studied in 33 patients who received kidney grafts from one haplotype identical living related donor and who were followed for at least one year. Both actual graft and patient survival rates were 97 per cent at one year. Incidence and severity of acute rejection were reduced to a greater extent in patients treated with CsA than in patients treated with azathioprine (AZ). The incidence of infections was low, and no serious bacterial infection occurred in these 33 patients. In 17 of 33 patients with a deteriorative graft function caused by intractable nephrotoxicity, CsA was converted to AZ. The mean serum creatinine level of converted patients was significantly higher than that of patients maintained with CsA at each time when a dose of CsA was stepwise reduced from 14 mg/kg/day to 6 mg/kg/day. Conversion to AZ improved graft function dramatically, although it resulted in reversible acute rejections in 4 patients. CsA induced hepatotoxicity occurred in 10 patients, but in all normal liver function was restored with decrease in the dose. The potent immunosuppressive effect of CsA compensates for its side effects. However, CsA should be converted to AZ when the chronic nephrotoxicity persists at a late stage of post-transplantation.

Adolescent↗
PubMed1986

Immunohistochemical localization of apolipoprotein E in atherosclerotic lesions of the aorta and coronary arteries.

The distribution of apolipoprotein E (apo E) immunoreactive substances (IRS) in atherosclerotic lesions and lesion-free areas of the aorta and coronary arteries obtained from 17 autopsied cases was studied using a specific anti-apo E serum and the unlabeled peroxidase-antiperoxidase (PAP) method. In fatty streak lesions of the aorta, many cells containing apo E-IRS were found in the deeper layer of the intima and diffuse staining of apo E in the extracellular spaces was also noted. In more advanced lesions apo E-positive cells could not be found. Immunohistochemical findings of coronary arteries differed distinctly from those of the aorta in that the apo-E-positive cells were absent in the deeper layer of the intima. The endothelial cells of coronary arteries, but not those of the aorta, showed positive staining for apo E.

Adult↗
PubMed1986

Loss of plasma-generated vitamin D-binding protein in explants of mouse mammary gland in culture.

Selective removal of 6S plasma-generated vitamin D-binding protein from mouse mammary gland was achieved by a simple tissue culture technique. This binder was totally diluted out from the mammary explant in a time-dependent manner within 2 days of tissue culture, allowing conditions most suitable for 1,25-dihydroxyvitamin D3-receptor studies. In comparison with other methods to eliminate 6S plasma-generated vitamin D-binding protein the present technique is easy, simple and does not require the use of other vitamin D metabolites to study differential displacement of 1,25-dihydroxyvitamin D3 binding to the heterogeneous binding sites.

Animals↗
PubMed1986

Solitary late recurrence of renal cell carcinoma.

Solitary late recurrence is an unpredictable behavior pattern of renal cell carcinoma. We describe a patient with recurrence at the cranial bone 10 years after surgical management and another with recurrence at the sacral bone 13 years after treatment with radiotherapy and alpha-interferon. Both patients have been followed satisfactorily for 9 months. Unpredictable behavior of renal cell carcinoma makes lifelong followup of patients necessary. If a solitary recurrence is detected operative management definitely should be considered depending on the site of recurrence.

Carcinoma, Renal Cell↗
PubMed1986

Paracrine regulation of mammary gland growth.

The growth and differentiation of the mammary gland is a complex process involving the interactions of various steroid and polypeptide hormones. The mammary growth occurs in a discontinued way during five distinct phases, i.e. fetal, prepubertal, postpubertal, pregnancy, and early lactation periods. The gland expresses its differentiated function by producing milk during the period of lactation. Although the mammary gland has been regarded as one of the well-known target tissues for various types of hormones, evidence has been accumulating in recent years indicating the involvement of other factors and substances in the process of mammary growth and differentiation. In this chapter the importance of the mesenchymal component in mammary epithelial cell growth has been documented. This component, including embryonic mesenchyme and adipocytes in adult tissue, play an essential role by not only serving as a structural entity of the gland but also by producing extracellular matrix substances and various factors that promote the growth, morphologic development and differentiation of mammary epithelium in a paracrine fashion. Other possible paracrine peptide factors for mammary cell growth have been isolated from several other sources including mammary tumors and milk. Thus, it is possible that paracrine growth factors play a role in mammary tumorigenesis. Since most of these factors are present in minute amounts, it is difficult to obtain pure forms of these factors in sufficient amounts for detailed physicochemical characterization. Moreover, further studies are needed to assess the physiological importance of these growth factors, their mode of action, and the mechanism of regulation relating to their production. It is conceivable that some mammary paracrine agents interact with each other or with endocrine agents in promoting the normal and neoplastic growth of mammary cells. Furthermore, the possibility exists that the production and release of paracrine factors are under the endocrine control. In view of the rapid progress and great interest in this area, these questions may be answered before long, along with the discovery of some other new growth regulating agents in this system. Clearly such information is important for understanding the complex process of normal and neoplastic growth of the mammary gland.

Animals↗
PubMed1986

Hormonal regulation of the synthesis of casein and alpha-lactalbumin in a primary mammary cell culture system.

The addition of 5 micrograms/ml of both insulin and prolactin, 3 microM cortisol and 5% fetal bovine serum stimulated casein synthesis during a 5 day culture of mammary epithelium from lactating mice using a floating collagen gel as a culture substratum. Omission of any of the three hormones or serum decreased casein synthesis substantially. The use of 10% serum or the attached gel culture system also decreased casein synthesis. Cells cultured with the combination of the three hormones and 5% serum contained a low level of casein mRNA on day 2, but it increased to much higher levels on day 4 and 5, amounting to over 30% of total mRNA on day 5. In contrast to casein synthesis, the maximal increase in alpha-lactalbumin synthesis required the presence of 0.03 microM cortisol. The combination of insulin, prolactin and 3 microM cortisol or insulin and prolactin elicited smaller increases. The translatable mRNA for alpha-lactalbumin in cells cultured with insulin, cortisol and prolactin for 5 days was detected, but not in cells with insulin and cortisol. Both a high and low concentration of cortisol in combination with insulin increased prolactin binding capacity of cultured cells to the same extent, whereas cells cultured with insulin alone contained much lower levels of prolactin binding. The difference in the capacity of prolactin binding between cells cultured with insulin alone and those cultured with insulin and cortisol correlated well with their ability to synthesize casein in response to prolactin.

Animals↗
PubMed1986

Induction of distinct types of spontaneous electrical activities in mammary epithelial cells by epidermal growth factor and insulin.

Electrophysiological measurements of the membrane potentials of mouse mammary epithelial cells in primary culture revealed the presence of spontaneous-oscillating-hyperpolarizing potentials in cells incubated with epidermal growth factor. The hyperpolarizing potentials were 5-20 mV in amplitude and about 10 sec in duration. The peak height of the response was reduced by hyperpolarization, and the input membrane resistance decreased during the response. The response was probably due to activation of K+ channels. The latency period for the epidermal growth factor induction of the hyperpolarizing potential was approximately 3 hr. In contrast, insulin induced spontaneous-depolarizing potentials that were about 5 mV in amplitude and 1 sec in duration. The depolarizing potentials were attributed to activity of ion channels, since the peak height was dependent on the membrane potential and the depolarizing potential was accompanied by a decrease of input membrane resistance. The time lag for the induction of the depolarizing potential was 6-12 hr. Other hormones involved in mammary cell differentiation, such as cortisol and prolactin, neither induced the depolarizing potentials nor changed the induction of depolarizing potential by insulin. In addition, other growth factors, such as nerve growth factor and fibroblast growth factor, elicited no electrical activity.

Animals↗
PubMed1986

Experimental studies on death by fire in automobiles and exhaust gas poisoning.

Studies were made on the acid-base balance, blood gases, and carbon monoxide (CO), cyanide, and sulfur dioxide concentrations in the blood of albino rabbits that died from automobile exhaust gas poisoning (group I) or fires in cars (complete combustion, group II; incomplete combustion, group III). In group I, the temperature and CO concentration increased gradually to 35 degrees C and 5.2% in 70 min. The animals died after 9 min, when the values were 20 degrees C and 5.2%, respectively. In group II the animals died after 9 min, when the values were 55 degrees C and 1.95%, respectively. In group III, the temperature was very high (870 degrees C), but the CO concentration was not (0.6-1.3%) after 4 min. The animals died after 5 min. In all experimental groups, marked acidosis and hypoxemia were seen, but the CO2 tension (PCO2) was high, in contrast to previous studies on pure CO poisoning. In group I, the level of carboxyhemoglobin (CO-Hb) was significantly higher (91.2 +/- 3.4% in arterial blood, 87.5 +/- 8.1% in venous blood; p less than 0.01) than in groups II and III. Although the O2 tensions of venous and arterial blood (PvO2, PaO2) were very low, that of arterial blood was higher, suggesting that O2 was still being utilized in the tissues at the time of death. In group II, CO-Hb was high (57.7 +/- 16.0% in arterial blood, 61.2 +/- 20.6% in venous blood) and the acid-base balance indicated marked acidosis. In group III, the CO-Hb, PCO2 and cyanide levels in the blood were very high.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents, Traffic↗
PubMed1986

Marginal vascular change in pedicle skin flaps.

The changes of vascular patterns in pedicle skin flaps were studied in rats at various intervals after operation using microangiography, with the following results: (1) Vascular change was observed in the marginal area of the flap after operation, possibly related to the release of an angiogenic factor during anaerobic metabolism. (2) Both primary and secondary revascularization were observed in the flap, but the main process was found to be primary revascularization. (3) Four days after operation, revascularization was observed. (4) Longitudinal rearrangement of the vessels in the flap could not be observed. (5) At sutured areas where the stitches remained, severe vascular reaction continued for a longer period.

Anastomosis, Surgical↗