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Biomedical subjects

T Azuma

Publications and source records attributed to T Azuma.

At least 379 records · Page 21Linked to original sources
PubMed1981

Conduction velocity of peristaltic waves in the in vivo ureter: application of a new diameter gauge.

The conduction velocity of peristaltic movements of the canine ureter was measured under anaesthesia with a new type of diameter gauge using an image sensor. The peristaltic velocity was 34.1 +/- 6.2 mm/sec in 10 experiments. Noradrenaline at a low dosage of 1 microgram/kg i.v. reduced the resting diameter, increased the conduction velocity to 47--56 mm/sec, and approximately doubled the frequency of contraction. The application of acetylcholine also caused an increase in both frequency and conduction velocity (42--46 mm/sec). A plot of the conduction velocity against the mean period of peristaltic contraction was hyperbolic in shape.

Acetylcholine↗
PubMed1981

Identification of a third type of lambda light chain in mouse immunoglobulins.

A third type of mouse lambda chain was identified in the course of examining light chains from four myeloma proteins and two monoclonal antibodies. On the basis of their antigenic properties and a characteristic COOH-terminal tryptic peptide, the light chains from these immunoglobulins had previously been provisionally identified as lambda 2 chains. However, four of these chains, designated now as lambda 3 (or lambda III), were found to share constant region features that clearly distinguish them from the other types of mouse lambda chains (lambda 1 and lambda 2). The amino acid sequence of more than 90% of the lambda 3 constant region (from position 120 to the COOH-terminus) was determined. In this region the lambda 3 sequence differs from the lambda 2 constant region at 5 positions and from the lambda 1 constant region at about 30 positions.

Amino Acid Sequence↗
PubMed1981

Androgenic action of glucocorticoids on the granular ducts of mouse submandibular glands.

The administration of cortisol acetate and dexamethasone to castrated-adrenalectomized mice increased the submandibular gland weight, the granular duct cell size of the gland and the number of androgen-dependent granules detected with the staining for tryptophan in the duct cell. These changes were not as pronounced as when testosterone propionate was given. Similar effects on the duct cells and an increase in androgen-dependent esteroprotease activity of the submandibular glands were observed in castrated mice, but not in mice with testicular feminization which are genetically deficient in androgen receptors. These results suggest that glucocorticoids exert a certain degree of androgenic action on the granular duct cell through androgen receptors when androgens are absent or deficient.

Adrenalectomy↗
PubMed1981

[The mode of action of ATP on the isolated internal carotid artery (author's transl)].

Adenosine triphosphate (ATP) has been known to induce vasodilation in various vascular beds. Recently, we reported that ATP produced vasoconstrictions in isolated internal and external carotid arteries of dogs. In the present study, the mode of the ATP-induced vasoconstriction in the internal carotid artery was analysed from the physiological and pharmacological points of view. The results obtained were as follows: 1) ATP (5 X 10(-6) approximately 2 X 10(-4) M) caused dose-dependent vasoconstrictions in the internal carotid artery. 2) The ATP-induced vasoconstriction was not affected by pretreatment with phenoxybenzamine, propranolol, atropine, cyproheptadine, or tetrodotoxin. 3) Verapamil suppressed dose-dependently the contractile response. 4) ATP caused no vasoconstriction in a calcium-free Krebs solution containing Im M EGTA. 5) ATP produced no further vasoconstriction in the preparation which had been in a state of contracture in a high potassium Krebs solution. These results suggest that an increase of potential-dependent Ca++ influx into the arterial smooth muscle cells may play a major role in the ATP-induced vasoconstriction.

Adenosine Triphosphate↗
PubMed1980

A camera-type diameter gauge applicable to small blood and lymph vessels.

A camera-type diameter gauge was constructed and used in physiological experiments. The distinctive features of the design and use of the gauge may be summarized as follows. Installation of an image sensor in the focal plane of a single-lens reflex camera equipped with a set of extension tubes which makes it possible to measure outer diameters of blood and lymph vessels as small as 100 micrometer. Using the gauge, we can distinguish a diameter change of about 12 micrometer. Simultaneous measurements of the diameters of two different vessels can be made using two window signals generated independently at desired moments for appropriate periods within the video scans.

Animals↗
PubMed1980

An approach to the pathogenesis of "white finger" induced by vibratory stimulation: acute but sustained changes in vascular responsiveness of canine hindlimb to noradrenaline.

A fixed vibratory stimulation (60 Hz in frequency, 3 g in acceleration, and 2.2 mm in amplitude) was applied to a hindlimb (test limb) of dogs anaesthetised with sodium pentobarbital. Peripheral vascular resistance in the test limb was calculated as the ratio of mean pressure difference between the femoral artery and the femoral vein to the rate of femoral arterial blood flow. By means of a highly sensitive clinical thermometer, interdigital temperature was recorded not only from the test limb but also from a forelimb (control limb). The vibratory stimulation significantly reduced the peripheral resistance in the test limb. The increase in peripheral resistance induced by noradrenaline administration was suppressed during, and enhanced 1 h after, the stimulation. With the start of the vibratory stimulation, interdigital temperature in the test limb rose gradually and reached a constant level. The temperature first went below, and then returned to, the initial level after interruption of the stimulation. No change in the temperature was produced in the control limb. The decrease of temperature induced by noradrenaline administration was suppressed during, and enhanced 1 h after, the stimulation. These results indicate that, even in the living body, the conclusion of our previously report is valid: ie the responsiveness of arterial smooth muscle to noradrenaline decreases during, and increases soon after, vibratory stimulation. Assuming that our results obtained from acute experiments can be applicable to human digital arteries, the occurrence of "white fingers" on vibration disease may be understood in terms of vibration-induced hyperresponsiveness following stimulation.

Animals↗
PubMed1980

Active and passive mechanical characteristics of bovine mesenteric lymphatics.

Pressure-volume and pressure-radius relationships in lymphangions isolated from bovine mesenteric lymphatics were similar in pattern with those in the vein. Circumferential modulus of elasticity of the lymphatics ranged from 4.2 x 10(4) tatic walls. The contractile force increased in early stages of distension and decreased after an optimal intraluminal pressure was attained. The spontaneous activity was also affected by the rate of wall deformation. The pacemaker site of spontaneous activity seemed to be in the wall in the immediate vicinity of the inlet valve of a lymphangion. The activity propagated with a velocity of 4-5 mm/s. Ejection fraction of a lymphangion was between 45 and 65%. The endurance limit of the lymphatic valve was 68.4 +/- 7.6 cmH2O in specimens of about 3 mm in outer diameter. These findings suggested that lymphatic smooth muscle seemed to play a major role in elastic behavior of the wall and in regulation of the spontaneous activity, thereby affecting significantly passive and active lymph transport.

Animals↗
PubMed1980

Paradoxical relaxation of arterial strips induced by vasoconstrictive agents.

Longitudinal strips isolated from canine distributing muscular arteries were relaxed by noradrenaline and contracted by papaverine. This paradoxical relaxation and contraction may be due to a helical and circular arrangement of smooth muscle in the wall which is incompressible. Various vasoconstrictive agents, including noradrenaline, produced a circumferential contraction and longitudinal relaxation in muscular arteries. Vasodilator agents produced the opposite effect. The direction and magnitude of response of a helical strip to a vasoactive substance depended upon its sectioning angle from the transverse axis of the vessel.

Adenosine↗