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Biomedical subjects

M Ohtsuka

Publications and source records attributed to M Ohtsuka.

At least 217 records · Page 12Linked to original sources
PubMed1983

Topography and ultrastructure of LHRH- and somatostatin-containing axonal terminals in the median eminence of rats.

The topography and ultrastructure of LHRH and somatostatin nerve fibers in the median eminence in male rats were investigated with special reference to the relation between the fiber terminals and the perivascular space of the portal capillaries. Vibratome sections taken from the rostral and preinfundibular portions of the median eminence were immunostained with anti-LHRH or anti-somatostatin serum before plastic embedding for electron microscopy. In the external layer of the median eminence, the LHRH fibers did not directly contact the perivascular space, although they were in close proximity to the external surface of the median eminence. On the contrary, somatostatin fibers divided into branches in the external layer of the median eminence and terminated in direct contact with the perivascular space in the median eminence. LHRH fiber terminals contain immunoreactive granules, whereas somatostatin fibers are characterized by the presence of synaptic vesicle-like structures, vesicle ghosts and immunoreactive granules in their terminals. These topographical and ultrastructural differences might be regarded as a morphological manifestation of different mechanisms in the release of neurohormones.

Animals↗
PubMed1980

Pharmacological study on sympathetic inhibition of the urinary bladder in dogs.

The sympathetic inhibitory mechanism in dog urinary bladder studied. The bladder contractions induced by electrical stimulation of the pelvic nerve both proximal and distal to the pelvic plexus and by intraarterial administration of tetramethylammonium (TMA) were inhibited by stimulation of the hypogastric nerve and intraarterial injection of catecholamines. The inhibition by hypogastric nerve stimulation was more potent at the low frequency of pelvic nerve stimulation than at the high frequency. The inhibition of contraction induced by stimulation of the pre-plexal pelvic nerve was antagonized by phentolamine and propranolol, whereas the inhibition of contraction induced by stimulation of the post-plexal pelvic nerve and by TMA treatment were antagonized only by propranolol. It is concluded that inhibition by hypogastric nerve stimulation of bladder contraction induced by pelvic nerve stimulation is composed of two different components. One occurs at the ganglia in the pelvic plexus and is mediated by alpha-adrenoceptors. The other occurs at the post-plexal pelvic pathway, probably at the ganglia in the bladder wall or on the muscle cells, and is mediated by beta-adrenoceptors. Moreover, the alpha-adrenergic action facilitated the pelvic nerve excitation in its pathway from the ganglionic cell bodies to the muscle cells.

Animals↗
PubMed1979

Seroconversion to human-cytomegalovirus-specific pre-early nuclear antigens in renal transplant recipients.

Seroconversion to human cytomegalovirus (H-CMV)-specific antigens was observed in 8 out of 9 renal transplant recipients. In 7 of the 8 recipients antibody to "pre-early nuclear antigens" (PENA), which are detectable in human embryonic lung cells within 1 hr of H-CMV infection by anti-complement immunofluorescence staining, developed concomitantly with the increase in other antibodies including anti-early antigens (EA), anti-nuclear inclusions (NI), and complement-fixing (CF) antibody in 1--2 months after transplantation. About 1 year later, anti-PENA and anti-EA titers were concomitantly decreased in 2 recipients, whereas anti-NI and CF antibody titers were maintained at elevated levels in all the seroconverted recipients. These results support the idea that the development of antibody to PENA, like antibody to EA, may represent a current or recent infection with (or reactivation of) H-CMV. In one patient, antibody to PENA did not develop through the observation period despite increases in antibody to EA and other antibodies; this lends support to immunological distinctness of PENA from EA.

Adult↗
PubMed1977

Relaxant effect of aspirin-like drugs on isolated guinea pig tracheal chain.

The interrelation of the inhibitory effect of aspirin-like drugs on the resting tonus of tracheal chain in guinea pigs, arachidonic acid-induced contraction in rat stomach fundus strips and bradykinin-induced bronchoconstriction in guinea pigs in vivo was investigated. All the drugs tested produced a dose-related inhibitory action on the resting tonus of the tracheal chain in comparatively low doses. Diclofenac was the most potent of all the drugs and was equal in activity to isoproterenol, followed in descending order by flufenamic acid, mefenamic acid, indomethacin, ibuprofen, phenylbutazone, oxyphenbutazone and aspirin. These aspirin-like drugs also inhibited arachidonic acid-induced contraction in rat stomach fundus strips. A highly significant correlation was observed between the potency of inhibition of the arachidonic acid-induced contraction and the relaxant effect on the tracheal chain. Moreover, the drugs antagonized bradykinin-induced bronchoconstriction in guinea pigs in vivo and the order of potency roughly paralleled that of the tracheal chain. These results suggest that the aspirin-like drugs produce a reduction in resting tonus of the isolated guinea pig tracheal chain by inhibition of intramural biosynthesis of prostaglandin endoperoxides.

Animals↗