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T Azuma

Publications and source records attributed to T Azuma.

At least 343 records · Page 19Linked to original sources
PubMed1984

Diversity at the variable-joining region boundary of lambda light chains has a pronounced effect on immunoglobulin ligand-binding activity.

By recombining lambda light (L) chains having known variable (V) region amino acid or nucleotide sequences with a heavy (H) chain from a myeloma protein or a monoclonal antibody, we obtained reconstituted Igs that differed from each other in sequence by only one or a few amino acid substitutions at known L chain positions. Differences in affinity of the reconstituted Igs for 2,4-dinitrophenyl (DNP) ligands revealed a pronounced effect on Ig binding activity of amino acids at the V-J boundary of the lambda chains. In one instance, two reconstituted Igs that differed about 1000-fold in affinity for epsilon-DNP-aminocaproate differed in primary structure by only a single tyrosine-phenylalanine substitution at the V-J junction (position 98) of their lambda 2 chains--i.e., by only one out of approximately 660 amino acid residues (L + H chains). By focusing on affinity changes, chains with unusual V lambda-J lambda junctional residues were identified. It is possible that because of a critical effect on tertiary structure junctional amino acid variations arising from gene segment assembly (V/J and perhaps V/D/J) constitute an important source of ligand-binding diversity of antibodies.

Amino Acid Sequence↗
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

High erythroid burst-promoting activity in sera from umbilical cord blood.

Using methylcellulose clonal cell cultures, we examined human erythroid burst-promoting activity (BPA) in sera obtained from umbilical cord blood. BPA was measured on the basis of the number of erythroid bursts (BFU-E) and hemoglobin synthesis when peripheral blood mononuclear cells were cultured with cord blood serum in the presence of 1.0 U/ml erythropoietin (Epo) at low fetal calf serum concentration (10%). Controls were cultured with adult serum. The number of BFU-E and hemoglobin synthesis increased in culture to which cord blood serum had been added, and the enhancing effects of cord blood serum on erythroid burst formation were more pronounced than in control cultures with 2.0 U/ml Epo. No erythroid bursts, however, grew in the cultures with cord blood serum in the absence of Epo. Increased sensitivity of erythroid burst formation to low concentrations of Epo was observed in cultures containing cord blood serum. Dose-relationships between the concentrations of cord blood serum and the number of BFU-E and hemoglobin synthesis were clearly observed. We therefore concluded that the stimulatory effects of cord blood serum on erythroid burst formation may be due to BPA, one of the factors required for the proliferation of erythroid precursors at an early stage.

Adult↗
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

[Angiographic analysis of vascular anatomy in gastric cancer].

Celiac, left gastric, common hepatic and superior mesenteric angiography was performed in 296 gastric cancer patients. Relationship between anatomical variations and the mode of lymphatic metastasis was discussed. The emergence of right gastric artery was from hepatic artery proper in 46.9%, right, middle and left hepatic in 26.4%, common hepatic and gastroduodenal in 18.6%, and others in 5.4%. The rate of metastasis to suprapyloric nodes was the highest (20.0%) among the cases, in which the right gastric artery was given off distal to the hepatic artery proper. Left gastric artery emerged from the celiac in 94.9%, splenic in 2.7%, abdominal aorta in 2.1%, and common hepatic in 0.3%. Knowledge of the origin of the arteries is essential to thorough dissection of the perivascular lymph nodes. The accessory hepatic arteries emerged from left gastric artery in 17.9% of the cases, in which the rate of lymph node metastasis along left gastric artery was higher than others. Left gastric artery should be severed at its point of emergence for thorough dissection of lymph nodes along this artery in gastric cancer. However, the fact that 20.8% of accessory left hepatic arteries were perfusing more than 2 liver segments must be into consideration.

Angiography↗
PubMed1983

Quantitative of anti-NP (4-hydroxy-3-nitrophenyl)-acetyl idiotype expression on spleen and thymus cells.

Direct binding of 125I-labeled rabbit anti-NPb idiotype antibodies (RaId) was used to quantitate the expression by immune spleen and thymus cells of NPbId, the characteristic Id of the lambda 1-containing antibodies made by C57BL/6 (B6) mice to the (4-hydroxy-3-nitrophenyl)acetyl (NP) group. Direct binding of RaId by B and T cell preparations reached a maximum of 12 ng RaId per 10(8) cells at 7 days after immunization. Spleen T cell preparations maintained similar levels of binding after positive selection for Thy-1.2+ cells and overnight culture. RaId binding was also demonstrated for immune B6 thymus cells and for spleen and thymus cells of immune SJL mice, which have the appropriate heavy chain allotype for NPbId expression but have only barely detectable serum Id. However, the NPbId of T and B cell preparations were indistinguishable by (a) the susceptibility of RaId binding by the cells to inhibition by hapten or by antibodies to the variable regions of lambda light chains (anti-V lambda) and by (b) the ability of anti-V lambda and of monoclonal antibodies to the constant region of lambda 1 chains (anti-C lambda 1) to immunoprecipitate antigen (NP10-bovine serum albumin)-binding proteins from detergent extracts of isotopically labeled cells. The results strongly imply that virtually all of the NPbId of T cell preparations is due to conventional NPbId antibody that is tightly bound to T cells. The results do not, however, exclude the possibility that the T cell preparations contain a trace amount (less than or equal to 1 ng/10(8) cells) of unusual NPbId-like molecules that lack lambda chains.

Animals↗
PubMed1983

A preliminary study on clinical application of Nd:YAG laser to the face and head.

Preliminary experiments were carried out for use of the Nd:YAG laser therapy of malignant tumors of the head and face. Because bone and brain tissue lie under the soft tissues in the face and head, the authors prepared two experimental models and examined the thermal effects of laser irradiation using three irradiating methods, single-pulse, automatic running, and manual. In experiments using results from these models, a temperature rise inducing protein coagulation did not occur under the surface of the soft tissue under the bone in both models. With automatic running irradiation, the temperature rise in the surface of the soft tissue under the bone was about 5 degrees C at 60 W with a running speed of 4 mm/sec in model I. These conditions were considered to be sufficiently within safe limits. In the second model, it was estimated that no thermal effects would be exerted on the soft tissue under the bone at 60 W or less with a running speed of 8 mm/sec or less. Using manual irradiation, no thermal disturbance of the soft tissue under the bone was induced in the first model, but without a shortening of irradiation time or an increase in irradiation distance this method could cause thermal damage to the second model and must be taken into consideration.

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

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

[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↗