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Biomedical subjects

T Ohhashi

Publications and source records attributed to T Ohhashi.

At least 91 records · Page 5Linked to original sources
PubMed1985

[Hypothalamic hamartoma with precocious puberty--a case report].

A case of hypothalamic hamartoma with precocious puberty is presented and the literature of reported cases is reviewed. An 8-year-old boy was admitted to our hospital because of precocious puberty and mental retardation. His genital development was Tanner's stage 4 and pubic hair was Tanner's stage 3. Bone age was 11 years. Plain CT showed an isodense mass in the suprasellar cistern which was not enhanced following contrast administration. Metrizamide CT cisternography showed a filling defect in the suprasellar cistern. Endocrinological evaluation revealed high levels of serum luteinizing hormone (LH) and testosterone with a marked response of LH to LH-RH injection. A left frontotemporal craniotomy was performed and the tumor was partially removed. The tumor was gray, firm and well-circumscribed with poor vascularity. Postoperatively, a right oculomotor palsy and transient diabetes insipidus developed. He was discharged ambulatory one month later. Serum LH and testosterone returned to normal and the response of LH to LH-RH injection became normal. Hamartoma was diagnosed on histological examination. Electron micrographic study showed numerous dense granules with approximately 0.1 mu in diameter, in which Judge proved LH-RH by immunofluorescent study in 1977. Our case supports the hypothesis that hypothalamic hamartoma may cause precocious puberty by autonomous secretion of LH-RH and we consider that neurosurgical treatment is recommended.

Child↗
PubMed1984

Complement system in abnormal pregnancy and chorionic neoplasia: immunotherapy and chemotherapy of chorionic neoplasia.

In normal pregnancy, the activity of the alternate pathway elevates latently and compensatorily for the suppression of cellular immunity. Aging of the placenta becomes a trigger for the onset of labor and production of C3-a. In cases of hydatidiform mole, abruptio placentae, threatened abortion, and chorionic malignancy, the activity of the complement system is depressed, especially that of C3-activator and alternate pathway. This may in turn result from activation of complement by the pathologic lesion of the chorionic villi. In pathologic lesions of the placenta, activation of alternate pathway can lead to a number of diseases. Immunotherapy is effective in the prevention of malignant transformation of hydatidiform mole. Immunotherapy and combination chemotherapy are markedly effective for treatment of metastatic chorionic malignancy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1984

Variegated effects of prostaglandins on spontaneous activity in bovine mesenteric lymphatics.

The effects of PGs (PGA2, PGB2, PGE2, PGF2 alpha, PGI2, and 6-keto PGF1 alpha) were investigated quantitatively in insolated bovine mesenteric lymphatics for elucidating the possible significance of PGs in lymph propulsion. 10(-8) M PGF2 alpha, PGA2, and PGB2 produced recognizable increases of frequency and amplitude of spontaneous contractions. The positive chrono- and inotropic responses were enhanced with increasing concentration of the PGs from 10(-8) to 10(-6) M. Both PGE2 and PGI2 in a concentration range from 10(-8) to 10(-6) M caused dose-related reductions in the amplitude of spontaneous contractions. No decrease in contraction rhythm was observed by the administration of PGI2 and PGE2 at concentrations lower than 5 X 10(-7)M. All of the above-mentioned responses induced by PGF2 alpha, PGA2, PGB2, PGI2, and PGE2 were not inhibited by pretreatment with alpha- and beta-adrenergic blocking agents, muscarinic antagonist, antihistamics, and serotonic antagonist. These findings suggest that PGF2 alpha, PGA2, and PGB2 in a low concentration may facilitate lymph flow of bovine mesenteric lymphatics in the living body, since the spontaneous contractions of lymphatic smooth muscle may drive lymph centripetally in the presence of direction valves. On the other hand, PGI2 and PGE2 may cause an inhibition of lymph transport.

Adrenergic alpha-Antagonists↗
PubMed1984

Sympathetic effects on spontaneous activity in bovine mesenteric lymphatics.

To investigate the effects of autonomic nerves on the spontaneous activity, responses of valvular and intervalvular segments of isolated bovine mesenteric lymphatics to 60-strains of pulses (50 V for 0.5 ms at 2 Hz) have been studied under the influence of various drugs. There was a marked difference in response to transmural stimulation between the valvular and intervalvular segments. In the valvular segment, the stimulation arrested the spontaneous activity. However, the rhythm of spontaneous contractions was markedly accelerated during the stimulation in the intervalvular segment. Both inhibitory and excitatory effects were completely blocked by tetrodotoxin and guanethidine, potentiated by cocaine, and unaffected by hexamethonium and atropine. Propranolol blocked the inhibitory effect of the stimulation in the valvular segment. Pretreatment of the intervalvular segment with phentolamine converted the normal excitatory effect of the stimulation into an inhibitory influence. No change in rhythm was brought about by the stimulation in the presence of propranolol and phentolamine in either segment. These results suggest that transmural electrical stimulation causes the release of norepinephrine from postganglionic sympathetic nerve terminals in the vicinity of pacemaker cells and that beta-adrenoceptors are predominant in the valvular region of the lymph vessel.

Animals↗
PubMed1984

Redistribution of flow between canine isolated internal and external carotid arteries by vasoactive substances.

A Y-shaped segment consisting of the common, internal, and external carotid arteries was isolated from the canine carotid artery. The preparation has the advantage of allowing direct comparison of responses to vasoactive substances in the internal and external carotid arteries. It was perfused at a constant rate (within the range of 10-15 ml/min) through the common carotid with either Locke's solution or arterial blood led from a support dog. Adding norepinephrine or epinephrine to the perfusate raised the perfusion pressure, increased the flow along the internal carotid branch, and decreased it in the external carotid branch in the blood-perfused experiments but not in the saline-perfused ones. In contrast, 5-hydroxytryptamine, prostaglandin F2 alpha, and ATP caused a decrease in internal carotid flow and an increase in external carotid flow, raising the perfusion pressure in both experiments. Controlled bleeding of the support dog (at the rate of 4 ml/(kg X min] produced a similar result to that produced by exogenous norepinephrine or epinephrine. These findings may suggest that a redistribution of blood flow between the larger internal and external carotid arteries can be induced by a difference of responsiveness to certain vasoactive substances between the two arteries.

Adenosine Diphosphate↗
PubMed1984

The mode of ATP-induced vasoconstriction in the canine internal carotid artery.

The mode of the ATP-induced vasoconstriction in the internal carotid artery was studied from the physiological and pharmacological points of view. ATP caused dose-dependent vasoconstrictions in the canine internal carotid artery. The ATP-induced vasoconstriction was not affected by pretreatment with phenoxybenzamine, propranolol, atropine, cyproheptadine, or tetrodotoxin. Verapamil suppressed the contractile response. ATP produced no vasoconstriction in a calcium-free Krebs solution containing 1 mM EGTA nor augmentation of Ca2+-induced contraction in potassium-depolarized tissues. These results suggest that an increase of potential-dependent Ca2+ influx into the arterial smooth muscle may play a major role in the ATP-induced vasoconstriction.

Adenosine Triphosphate↗
PubMed1984

Inhibition of autologous mixed lymphocyte reaction by monoclonal antibodies specific for the beta chain of HLA-DR antigens.

Recent studies using rabbit antisera to the separated HLA-DR alpha and beta subunits have suggested that alpha chain-specific, but not beta chain-specific, antisera inhibit T cell proliferative responses in primary and secondary human autologous mixed lymphocyte reaction (AMLR). In the present study, with the aid of sequential co-precipitation assays and Western blotting methods, a monoclonal rat alloantibody 1E4, specific for the beta chain of rat class II molecules carrying an Ia determinant Ba-2.7, was characterized to recognize a monomorphic determinant located on the beta chain of DR antigens. This antibody and a murine monoclonal antibody HU-4, also specific for the beta chain of DR antigens, strongly inhibited both primary and secondary AMLR through a mechanism distinct from an antibody-dependent cell-mediated cytotoxicity reaction. These results indicate that the inhibition of AMLR is not a unique feature of DR alpha-specific antibodies.

Animals↗
PubMed1983

Effect of potassium on adrenergic nerve endings in bovine mesenteric lymphatics.

This work concerned the effect of KCl (60 mM) on noradrenaline efflux from aminergic nerve endings in bovine mesenteric lymphatics. In high potassium Krebs solution containing cocaine (10(-7) M), the lymphatics showed some phasic contractions followed by a tonic contraction with a high initial peak. The high KCl solution also caused a transient but statistically significant increase of tritiated noradrenaline efflux (P less than 0.01) which was not blocked by tetrodotoxin (10(-7) M). However, 5 X 10(-6) M 5-hydroxytryptamine or 10(-5) M prostaglandin F2 alpha produced a contraction of the lymphatic smooth muscle similar in magnitude to the contraction by 60 mM KCl. In this case, however, no increase was observed in 3H efflux. A Ca-antagonist, D-600 (10(-4) M) inhibited the potassium-induced rise in tritiated noradrenaline efflux and suppressed dose-dependently the contractile response to high potassium solution. These observations support the suggestion that the effect of KCl on 3H-release reflects an effect of kinetics of exchange across the nerve ending rather than an effect of contraction per se on isotope exchange through the complex extracellular matrix, and that the activation of Ca channels in the adrenergic nerve terminals may contribute to the release of noradrenaline in high KCl solution.

Adrenergic Fibers↗
PubMed1983

Factors modifying the local arterial hyperresponsiveness of vibration-induced white finger.

The extent and duration of the vibration-induced hyperresponsiveness of arterial smooth muscle to noradrenaline increased as the period of vibratory stimulation became longer. Division of a fixed stimulation time into a few shorter units interposed by intermissions decreased the extent and duration of the hyperresponsiveness. The shorter the length of each unit, the less the hyperresponsiveness. Verapamil effectively suppressed the appearance of the hyperresponsiveness, whereas pretreatment with phentolamine only partially inhibited its appearance. Administration of vitamin E was effective in suppressing the vibration-induced rise of responsiveness to noradrenaline in plasma.

Animals↗
PubMed1983

Immunochemical evidence for multiple beta units of the class II molecule in the rat.

The RT1-B/D region-associated antigens which were serologically defined in the previous study (Ohhashi et al., 1981), were partially purified from membranes of a rat B cell leukaemia, KNL-14. Sequential immunoprecipitation test, with the partially purified 125I-B/Dak preparation using four different rat alloantisera, including a monoclonal antibody, disclosed three distinctive populations of beta units of the class II molecules. Highly purified beta units of three discriminable class II molecules were shown to have different structural properties in terms of molecular weights and of electrophoretic profiles on the isoelectric focusing. The beta units shifted to a position of higher molecular weight on SDS-PAGE under reducing condition, thus suggesting to carry intradisulfide bonds. Furthermore, the highly purified beta units cross-reacted with murine anti-Ia sera. The rebinding test revealed that at least two discriminable species of beta units cross-react with anti-I-Ak monoclonal antibody, whereas beta units purified by binding with the 1E4 monoclonal antibody cross-reacted with anti-I-Ab and/or anti-I-Ad antiserum. On the basis of structural and antigenic properties, we have postulated that the rat class II region can be divided into at least three subregions, each containing a locus which encodes a distinctive beta unit of the class II molecule.

Animals↗
PubMed1983

Bradykinin-induced contractions of bovine mesenteric lymphatics.

The mode of action of bradykinin (BK) on bovine mesenteric lymphatics was investigated by recording isometric tensions and action potentials in the isolated longitudinal segments. Addition of BK in concentrations from 10(-10) to 4 X 10(-6) M caused dose-related tonic contractions. BK in a low concentration accelerated the rhythm of action potential discharges in the spontaneously beating preparations and elicited frequent discharges of action potentials and a rapid rise in smooth muscle tone associated with phasic contractions. BK in high concentrations (more than 10(-7) M) caused a further rise of tension in the preparations which had already been depolarized in a high-K solution. The contraction induced by 4 X 10(-9) M-BK in the standard solution was abolished in a Ca-free environment or in the presence of a Ca-antagonist, 10(-4) M-D-600, though more than 50% of the contraction caused by 10(-6) M-BK still remained in both circumstances. In a Ca-free solution containing 1 mM-EGTA (Ca-free standard solution), 10(-6) M-BK caused a slight contraction even after high-K-induced contractions were completely blocked. The contractile response to 10(-6) M-BK in the Ca-free standard solution was augmented after activation of beta-receptors. It is concluded that the BK-induced contractions may be closely related to an increased Ca influx through the membrane and release of membrane-bound and intracellular Ca. The increased uptake of Ca into the BK-sensitive intracellular store may contribute to the relaxing effect of beta-agonist.

Action Potentials↗
PubMed1983

Vasoactive intestinal peptide inhibitory innervation in bovine mesenteric lymphatics. A histochemical and pharmacological study.

The localization of vasoactive intestinal peptide-immunoreactive nerves innervating bovine lymphatic vessels was studied by an immunohistochemical technique. Nerve fibers containing vasoactive intestinal peptide immunoreactivity were present in the smooth muscle layers as well as in the adventitia of all mesenteric lymphatics that were examined. The effect of vasoactive intestinal peptide on isolated lymphatic vessels in vitro was studied. Vasoactive intestinal peptide caused a concentration-dependent relaxation of bradykinin-induced contractions of lymphatic vessels. The threshold and maximum relaxations were achieved with vasoactive intestinal peptide at concentrations less than 6 X 10(-9) M and 3 X 10(-7) M, respectively. The relaxant response to vasoactive intestinal peptide was not modified by atropine, propranolol, bretylium, or tetrodotoxin. These results suggest that vasoactive intestinal peptide may be a possible inhibitory neurotransmitter that causes relaxation of lymphatic vessels.

Animals↗
PubMed1983

[Characteristics of alpha adrenoceptors of lymphatics and their physiological significance].

We studied isolated bovine mesenteric lymphatics to investigate the pharmacological properties of the postjunctional-adrenoceptors. Rings of the lymph vessels were mounted for isometric tension recording in organ chambers filled with Krebs-Ringer bicarbonate solution. The lymph vessels contracted when exposed to phenylephrine and clonidine. The relative sensitivity of the vessels to clonidine was larger than to phenylephrine. Yohimbine was a competitive antagonist against phenylephrine and clonidine in the lymph vessels. Prazosin caused a parallel shift to the right of the dose-response curve to phenylephrine, and not to clonidine in the vessels. The Schild's plot for yohimbine in the lymph vessels suggests that the presence of both alpha 1- and alpha 2-like adrenoceptors on lymphatic smooth muscle cells.

Animals↗