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Biomedical subjects

S Yamazaki

Publications and source records attributed to S Yamazaki.

At least 595 records · Page 33Linked to original sources
PubMed1982

Alpha 2-adrenergic inhibition of insulin secretion via interference with cyclic AMP generation in rat pancreatic islets.

Glucose-induced secretion and cyclic AMP accumulation in isolated rat pancreatic islets as well as GTP-activated adenylate cyclase of the membrane-rich preparation from the islets were strongly inhibited by some alpha-adrenergic agonists. The relative potencies of the agonists, estimated according to their dose-dependent actions, were in such an order that clonidine greater than epinephrine (congruent to norepinephrine) greater than phenylephrine congruent to methoxamine, regardless of which of the three parameters (i.e., insulin release, cyclic AMP accumulation, and adenylate cyclase activity) was used for estimation. There was a highly significant correlation between the amounts of cyclic AMP accumulation and the rate of insulin release that were changed in response to these agonists. The order of the potencies of alpha-adrenergic antagonists to reverse epinephrine inhibition of these parameters was invariably yohimbine congruent to dihydroergotamine congruent to phenylephrine greater than prazosin. In conclusion, the rat islet cell membrane is equipped with alpha 2-adrenoceptors which are linked to adenylate cyclase to cause diminution of the cellular content of cyclic AMP; insulin secretion may be inhibited consequently.

Adenylyl Cyclases↗
PubMed1982

Spleen cell transfer induces T cell-dependent granulomas in tuberculous nude mice.

After IV infection with an attenuated strain of Mycobacterium bovis BCG, athymic nude mice produced a few hepatic granulomas; most of the other foci of bacterial parasitization lacked obvious cellular reactions. Nude mice BCG-infected four weeks earlier received spleen cells from normal euthymic littermates. After transient splenomegaly which peaked at about two weeks, numerous hepatic granulomas appeared by four weeks and the number of viable BCG decreased. The development of hepatic granulomas required viable spleen cells and depended on the spleen cell dose and corresponded with positive footpad reactions. The effective population seemed to be T cells, since they were sensitive to treatment with anti-brain associated theta antigen serum (antiBAT) plus complement, and were found in nylon-wool passed fractions. After transfer with sensitized spleen cells, adoptive immunity was observed, provided that the recipient BCG-infected nude mice had been splenectomized before transfer. AntiBAT plus complement treatment of the sensitized spleen cells decreased the granuloma-producing as well as antimycobacterial capacity. When BCG-infected nude mice were irradiated with 500 r of gamma ray, granuloma production was decreased after immune spleen cell transfer. Co-transfer of immune spleen cells with normal nude mouse bone marrow cells to BCG-infected irradiated nude recipients restored the granuloma-forming ability.

Animals↗
PubMed1982

Reconstruction of sternal defects with autologous bone grafts and myocutaneous flap of the latissimus dorsi muscle.

In one case of sternal metastasis associated with necrotic osteomyelitis from breast carcinoma we performed subtotal sternotomy including adjacent structures. The resulting defect over the pericardium was reconstructed by the fibula, ribs and a myocutaneous flap of the latissimus dorsi muscle for protection and stability of the anterior chest wall after the operation. The usefulness of the myocutaneous flap of latissimus dorsi muscle for skin coverage over a wide defect in the anterior chest wall is discussed.

Bone Neoplasms↗
PubMed1982

Structure of the inner retinal surface in simple diabetic retinopathy.

An eye with moderate simple diabetic retinopathy in a 47-year-old man was enucleated for rubeotic glaucoma of 2 months' duration and was subjected to histopathological and ultrastructural studies. Particular attention was paid to the structure of the retinal surface as examined by scanning electron microscopy. Six normal eyes and 2 eyes with long-standing central retinal vein occlusion served as the control. The inner retinal surface in normal eyes with posterior vitreous detachment appeared as a smooth, continuous sheet seen by scanning electron microscopy. No cell-like structure was detected on the retinal surface. In the eye with simple diabetic retinopathy, on the other hand, numerous spherical cells with pseudopodic protrusions were observed throughout the retinal surface which were identified as macrophages in light, scanning and transmission electron microscopic studies. The macrophages were particularly dense and were arranged in circinate pattern corresponding to circinate lesions within the retina. The macrophages were also densely populated in retinal areas with hard exudates. In areas adjacent to the macrophages, the inner retinal surface lost its smooth and continuous structure. The matrix in the inner limiting membrane disappeared in such areas so that a coarse network of filaments lay bare on the retinal surface. These findings indicate that the inner retinal surface would be pathologically altered in simple diabetic retinopathy, particularly where hard exudates are located.

Diabetic Retinopathy↗
PubMed1981

Seroepidemiologic studies of acute hemorrhagic conjunctivitis virus (enterovirus type 70) in West Africa. II. Studies with human sera collected in West African countries other than Ghana.

Human sera were collected in Senegal, Nigeria, Ivory Coast, Dahomey, Liberia, Gabon and Togo during the pre-epidemic period of acute hemorrhagic conjunctivitis (AHC) from 1965 to 1969, and tested for virus neutralizing (VN) antibody to enterovirus type 70 (EV70). Of these, 1109 (91%) were antibody negative (less than equal to 1:4), 116 (9%) neutralized at a dilution of 1:8 or over, and 45 (4%) at dilutions of at least 1:16. The distribution pattern is not significantly different from that of sera collected from Kenya in 1967 or from army recruits in the United States, Argentina, Brazil and Colombia in the 1960s. Sera collected during the post-epidemic period (1970 to 1977) in Senegal, Sierra Leone, Mali, Upper Volta, Chad, Niger and Gabon were also examined; 1573 (68%) were VN antibody negative (less than or equal to 1:4), while 733 (32%) and 433 (19%) had titers of 1:8 or greater and 1:16 or over, respectively. There is a significant difference in distribution between pre- and post-epidemic antibody titers (p less than 0.001), although the incidence of AHC was lower in these countries than in Ghana and Southeast Asia. The prevalence of VN antibodies tends to be lower in the dry, hot inland areas and thus humid coastal monsoonal climates and dense populations seem to favor the spread of AHC.

Adolescent↗
PubMed1981

Seroepidemiologic studies of acute hemorrhagic conjunctivitis virus (enterovirus type 70) in West Africa. III. Studies with animal sera from Ghana and Senegal.

One hundred and thirty-nine bovine sera collected in Senegal in 1968 and 1969, before the human pandemic of acute hemorrhagic conjunctivitis (AHC), and 145 sera collected in 1977, seven years after the introduction of AHC, were tested for virus neutralizing (VN) titers against enterovirus 70 (EV70) in neutralization tests. Positive rates of VN titers (1:16) were fairly constant (about 40%) in 1968 and 1969 but the proportion of positives from the 1977 collection was significantly higher (61%). The proportion of Ghanaian bovine sera positive in 1977 (39%) was comparable with those collected earlier in Senegal but the proportion was lower in sera of calves (7%). Similar studies were performed on sheep sera collected in 1966, 1967, 1968, and 1969 in Senegal. The proportions positive and the geometric mean titers (GMTs) peaked in alternate years: the proportions were 43% and 54% in 1966 and 1968 but dropped to 12% and 5% in 1967 and 1969, respectively. The prevalence rate for Ghanaian sheep sera in 1977 was comparable to the earlier figures in Senegal. The prevalence of VN (83%) and the GMT (1:27.28) in swine sera in Ghana in 1977 were much higher than those seen in chickens and dogs. However, 87 sera of wild monkeys caught in Senegal after 1970 were negative in neutralization tests. The VN substance detected in these domestic animals was found to be 2-mercaptoethanol sensitive; hence it is considered to belong to IgM. The results seem to favor the hypothesis that enterovirus type 70 (EV70) evolved from an animal enterovirus which shares a common antigen with EV70.

Animals↗
PubMed1981

[Effects on the manual function of men wearing cold-protective clothing to cold stress (author's transl)].

Subjects were exposed in a climatic chamber for 60 min to air temperature at -5 degrees C, -20 degrees C and -30 degrees C wearing cold-protective clothing. The following manual functions were studied as a function of air temperature, upper limb skin temperatures, mean skin temperatures or mean body temperatures: handgrip strength, pinch strength, bolt-removing task and counting task. The decline of skin temperatures was observed during cold exposure, wearing cold-protective clothing. At 60 min of cold exposure to air temperatures at -5 degrees C, -20 degrees C and -30 degrees C, mean skin temperatures were 30.2 degrees C, 27.8 degrees C and 26.5 degrees C respectively, then II-right-finger skin temperatures were 20.7 degrees C, 13.1 degrees C and 11.8 degrees C respectively. There were reductions only on limited number of manual functions as compared with functions under normal conditions, that is, bolt-removing task and handgrip strength did not significantly change during cold exposure, whereas pinch strength and counting task decreased with lower surface temperatures and body temperatures. Body or surface cooling resulted in reductions in pinch strength by the order of 50%. The rising of the body storage index, which was calculated from the change of the mean body temperature, resulted in a linear decrease in counting task. The capacity to perform manual handling task and muscle strength appeared to vary according to the muscle used for these performance and depending on the levels of cold stress. Body cooling, combined with local upper limb cooling, produced the largest performance decrements.

Adult↗