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Biomedical subjects

T Yao

Publications and source records attributed to T Yao.

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

Regulation of locus coeruleus neurons and splanchnic, sympathetic nerves by cardiovascular afferents.

The brain norepinephrine (NE) neurons in the nucleus locus coeruleus (LC) have been claimed to be involved both in the regulation of behavioral functions, e.g. vigilance and arousal reactions, and in cardiovascular control. Recent studies from this laboratory have also shown that cardiovascular, vagal afferents can participate in the regulation of the LC neurons in the rat. Utilizing electrophysiological techniques, we have now studied the effects of activation of blood volume receptors or arterial baroreceptors on the firing rate of single cells in the LC and, parallelly, on splanchnic, sympathetic discharge in the chloral hydrate anesthetized rat. Blood volume load (0.5-5 ml heparinized blood, intravenously administered) induced a reduction in both LC neuronal firing rate and splanchnic nerve activity (SNA), effects which were readily and completely reversed by withdrawal of the corresponding amount of blood. In comparison, the central LC neurons were more sensitive to blood volume expansion than the peripheral splanchnic nerves. The effects of blood volume load on LC and SNA remained unaffected after deafferention of arterial baroreceptors. Blood pressure elevation, induced by slow intravenous infusion of NE or angiotensin (AII) (total dose 2 micrograms/kg), caused an immediate reduction in both the firing rate of most of the LC cells tested as well as in SNA. While the effect on SNA was abolished by deafferentation of arterial baroreceptors, the effect on central LC activity remained largely unaffected. Consequently, these data strengthen the concept that brain NE neurons in the LC are subject to control by peripheral blood volume receptors, analogously to peripheral sympathetic nerves. Arterial baroreceptors may still participate in the control of central noradrenergic nerve activity, but in contrast to their function for SNA they are not critical for the inhibition of LC neurons by blood pressure elevation. Rather, these two cardiovascular afferent systems may participate in the physiological regulation of the LC activity in a complimentary and convergent fashion.

Afferent Pathways↗
PubMed1984

Effects of dietary butter fat on fecal bile acid excretion in patients with Crohn's disease on elemental diet.

The excretion rate of fecal bile acids was determined by gas-liquid chromatography in nine patients with Crohn's disease and six healthy volunteers under two dietary conditions with different amounts of fat: during nasoduodenal tube feeding with a fat-restricted elemental diet containing approximately 1.5 g/day of fat, and during the addition of 50 g/day of butterfat by peroral administration. The fecal bile acid excretion rate on the elemental diet was significantly greater in the patients with Crohn's disease than in the healthy controls. With ingestion of the additional fat, the excretion rate was significantly increased in the patients with Crohn's disease, but not significantly changed in the healthy controls. The bile acid excretion rate in Crohn's disease correlated with fecal fat excretion, but not with either fecal weight or disease activity. These studies show that the amount of dietary fat represents an important consideration in the evaluation of bile acid malabsorption in Crohn's disease.

Adolescent↗
PubMed1984

Factors influencing the healing rate of gastric ulcer in hospitalised subjects.

A multiple linear regression analysis was carried out on 75 inpatients with gastric ulcer. In order to elucidate the effects of various factors - endoscopic and roentgenological findings, age, sex, medical history, and drugs such as antacids, anticholinergics or both - on the healing rate, these factors were compared between those with ulcer which healed within eight weeks after treatment and those which did not. In patients over 50 years of age, alcohol consumption of over 60 g per day until admission, duration of present ulcer pain for over three months, single ulcer, ulcer located in the lesser curvature and uneven elevation around the ulcer, there was significant delaying effect on ulcer healing. Drug ingestion, sex, smoking habits until admission, size, depth, and shape of ulcer, coexisting gastritis, and past and family history of ulcer disease had no significant effect on healing after eight weeks. The patients with less than two unfavourable factors (n = 46) had the best healing rate (100%) compared with those with three (n = 20) or four or more (n = 9) unfavourable factors. The healing rate of the latter two groups was 60% and 22%, respectively (p less than 0.001). A prognostic score based on these six factors represents the severity of gastric ulcer disease with regard to the healing rate in patients prescribed antacids, and/or anticholinergic drugs.

Adult↗
PubMed1984

Immunological studies in Crohn's disease. I. Association with HLA systems in the Japanese.

We attempted to clarify the association between HLA and Crohn's disease. HLA-A, -B, -C and -DR locus antigens in 62 Japanese patients with Crohn's disease were analyzed and the results were compared with findings of 231 healthy Japanese. In the patients with Crohn's disease there was a strong association with HLA-DR4 and -DR5 (chi2 = 14 . 013, RR = 4 . 77 and chi2 = 9 . 345, RR = 5 . 04) and a weak association with HLA-Bw46 and -Bw51 (chi2 = 7 . 077, RR = 2 . 63, and chi2 = 5 . 401, RR = 2 . 52). There was a close association between HLA-DR5 in those with the ileocaecal type, and the -Bw51 and small intestine type. Therefore susceptibility to Crohn's disease may relate to specific allotypes on the human major histocompatibility complex. The correlation was weaker than the other diseases such as ankylosing spondylitis and Coeliac disease.

Crohn Disease↗
PubMed1984

Fundic gland polyposis in patients without familial adenomatosis coli: its incidence and clinical features.

Thirty-five cases of fundic gland polyposis detected by roentgenographic examination, gastrofiberscopy, and endoscopic biopsy were divided into two groups. The first group consisted of 23 cases without familial adenomatosis coli and is termed the nonadenomatosis coli group; the second group contained 12 cases with familial adenomatosis coli and is termed the familial adenomatosis coli group. Incidence of fundic gland polyposis was only 0.085% (23 of 27,000 cases) in the non-adenomatosis coli group but 38.7% (12 of 31 cases) in the familial adenomatosis coli group. In both groups, fundic gland polyps were multiple, small (less than 8 mm in diameter), and located in the body and fundus of the stomach. A solitary or large polyp was occasionally observed in the non-adenomatosis coli group. Histologic examination revealed simple hyperplasia of the fundic glands and microcysts in both groups. The age range was 51.6 +/- 12.3 yr (mean +/- SD) in the non-adenomatosis coli group and 25.3 +/- 8.6 yr in the familial adenomatosis coli group. The ratio of males to females was 5:18 in the non-adenomatosis coli group, and 7:5 in the familial adenomatosis coli group. The number of fundic gland polyps was smaller in the non-adenomatosis coli group than in the familial adenomatosis coli group. Our observations suggest that this lesion frequently coexists with familial adenomatosis coli, but that it is not specific to this disease.

Adolescent↗
PubMed1983

Characteristics of brachiocephalic and carotid sinus baroreceptors with non-medullated afferents in rabbit.

The characteristics of brachiocephalic and carotid sinus baroreceptors with non-medullated afferents have been studied in rabbits. The conduction velocities of 18 non-medullated fibers arising from the brachiocephalic baroreceptors were 0.4-0.8 m/s (0.59 +/- 0.03 m/s, mean +/- SE) and their thresholds were 74-104 mmHg (84 +/- 2 mmHg). 29 non-medullated carotid sinus baroreceptor afferents had thresholds ranging from 60 to 125 mmHg (92 +/- 3 mmHg). Their conduction velocities were 0.5-1.1 m/s (0.65 +/- 0.05 m/s). Blood pressure-baroreceptor response curves of both the brachiocephalic and the carotid sinus baroreceptors were constructed. As the aortic arch non-medullated baroreceptor afferents, the brachiocephalic and the carotid sinus baroreceptors with non-medullated afferents exhibited thresholds about 30 mmHg higher than the medullated ones, considerably lower firing rates, comparatively rapid adaptation and remarkable irregular discharge pattern. It is suggested that the non-medullated baroreceptor afferents are of little importance for the cardiovascular regulation under normal conditions but are likely to play an important role during a sudden rise in arterial pressure.

Adaptation, Physiological↗
PubMed1983

Adrenergic and pressure-induced modulation of carotid sinus baroreceptors in rabbit.

The sympathetic control of the carotid sinus baroreceptor activity was studied in rabbits. Stimulation of the cervical sympathetic trunk (10 Hz, 1 ms, 4-12 V) elicited an increase in discharge frequency of the non-medullated baroreceptor afferents but not of the medullated fibers. An isolated carotid sinus area preparation was used to examine the influence of noradrenaline perfusion on baroreceptor activity. Non-medullated baroreceptor afferents, but not the medullated afferents, responded to noradrenaline perfusion (10(-6) g/ml) with a significant increase in firing rate. Short-term resetting of the baroreceptors was also studied with the same preparation. After perfusing the sinus at a hypertensive level for 30 min the pressure-response curves of both the non-medullated and the medullated baroreceptor afferents shifted to the right with increased thresholds and decreased maximal discharge frequencies. The extent of the short-term resetting was greater in non-medullated afferents than in medullated ones. It is concluded that the carotid sinus baroreceptors with non-medullated afferents are under the sympathetic control. The physiological significance of this is discussed.

Animals↗
PubMed1983

Human gastric carcinoma: prognosis in relation to macroscopic and microscopic features of the primary tumor.

The correlation of prognosis with various clinical and pathologic factors was studied by use of multiple stepwise linear regression analysis among 77 patients undergoing resections for gastric cancer. Factors such as depth of penetration, invasion of the duodenum, macroscopic appearance, intramural and extramural growth pattern of the cancer, lymphatic or vascular invasion, and cancer cell-free dense submucosal fibrosis around the cancerous area were significant, and independent factors correlated with the prognosis, in that order. When these factors were taken into account, other factors such as sex and age of the patient, location, size, and histologic classification of the tumor, and folds' convergence were not significant.

Adenocarcinoma↗
PubMed1982

Long-lasting cardiovascular depressor response following sciatic stimulation in spontaneously hypertensive rats. Evidence for the involvement of central endorphin and serotonin systems.

A naloxone-reversible long-lasting depressor response induced by a prolonged low frequency stimulation of the sciatic nerve in conscious spontaneously hypertensive rats (SHRs) was reported in a previous paper. In the present study pharmacological tools were used to further investigate the neurotransmitters involved in this phenomenon. Naloxone infusion (20--25 mg/kg/h following a bolus dose of 10 mg/kg i.v.) attenuated significantly the depressor response, while dexamethasone pretreatment had no such effect, suggesting an important role of the brain endorphin system, but not of the pituitary beta-endorphin, in this depressor response. Since the concomitant increase in pain threshold produced by the sciatic stimulation exhibited a different time course of development and naloxone reversibility, it is suggested that the depressor response and the hypalgesic effect produced by the same stimulation are mediated via different types of opiate receptors in the brain. On the other hand, PCPA abolished the post-stimulatory depressor response whereas 5-HTP and zimelidine had additive effects on the sciatic stimulation-induced depressor response, suggesting the involvement of central serotonin systems in the mechanism of the response. The interaction between the central endorphin and the serotonin systems in the mediation of the post-stimulatory depressor response is discussed.

5-Hydroxytryptophan↗
PubMed1982

Long-lasting cardiovascular depression induced by acupuncture-like stimulation of the sciatic nerve in unanaesthetized spontaneously hypertensive rats.

The influence of a prolonged low frequency electrical stimulation of the somatic afferents on cardiovascular and sympathetic nerve activities was investigated in unanaesthetized spontaneously hypertensive rats (SHRs) and Wistar-Kyoto normotensive rats (WKRs). In SHR, an elevation of blood pressure, heart rate and splanchnic nerve outflow was elicited during a 30-min period of sciatic nerve stimulation. Following the cessation of the stimulation, depressor response and bradycardia slowly developed and lasted up to 12 h. Activation of the group III or A-delta afferent fibers was essential for this post-stimulatory response. The progressive depressor response and a parallelled reduction of the splanchnic nerve activity, reached their maxima at about 1 h after the termination of the sciatic stimulation. The magnitude of the post-stimulatory depressor response was correlated with the prestimulatory control blood pressure level. There were also behavioural changes accompanying the depressor response. The cardiovascular and the behavioural depression were immediately reversed by naloxone (10-15 mg/kg, i.v.). The post-stimulatory depressor response was still present after bilateral sino-aortic denervation, but was absent in animals anaesthetized with chloralose and urethane. Emotional stress produced by air-blowing on the animal resulted in pressor response and tachycardia during the period of the stressful stimulation, but there was no depressor response following the termination of air-blowing. These findings indicate a sympathetic and cardiovascular depression induced by a prolonged stimulation of the somatic group III or A-delta afferent fibers; its long duration and naloxone reversibility suggest the involvement of endorphins in the mechanism of this response. The physiological significance of the effects of the prolonged somatic afferent stimulation and its possible relations with acupuncture are discussed.

Acupuncture Therapy↗
PubMed1982

Naloxone reversible reduction in brain monoamine synthesis following sciatic nerve stimulation.

Brain monoaminergic neurons seem to be influenced by endogenous opioid systems as judged from largely indirect evidence. In an attempt to more directly study this interaction, we have analyzed the effect of sciatic nerve stimulation (rectangular pulses, frequency 3 Hz, pulse duration 0.2 msec, current intensity 6-20 times muscle twitch threshold) on the in vivo rate of tyrosine-and tryptophanhydroxylation, respectively, in the rat brain. This stimulation procedure has previously been shown to evoke naloxone reversible pain threshold elevation and a longlasting blood pressure reduction rats, with maximum reached about 1.5 h after stimulation. The formation of DOPA and 5-HTP in various parts of the central nervous system during 30 min after inhibition of L-amino-acid-decarboxylase by NSD 1015 was measured. Two hours after the sciatic nerve stimulation procedure a significant decrease in DOPA formation was obtained in the cerebral cortex and in the spinal cord. This effect was reversed by pretreatment with a high dose of naloxone (15 mg/kg s.c., 10 min before stimulation). A reduction in 5-HTP formation was also obtained in the cerebral cortex, with a concomitant reduction in tryptophan concentration. These effects appeared to be antagonized by naloxone treatment. In the spinal cord there was no change in the 5-HTP accumulation after stimulation, but an increase after stimulation plus naloxone pretreatment was obtained. These data infer that the activity of some central monoamine systems, such as the NA pathways originating in locus coeruleus can be reduced by physiological activation of endogenous opioid systems. This effect of the acupuncture like stimulation procedure may be related to clinically reported actions of acupuncture stimulation, which apart from pain relief include, for example, antagonism of heroin abstinence symptoms.

Animals↗
PubMed1982

Effects of total parenteral nutrition on colonic lesions in Crohn's disease: radiographic and endoscopic study.

Changes in the colonic lesions were studied by means of radiographic and colonofiberscopic examination in 7 cases with Crohn's disease treated with total parenteral nutrition (TPN) for an average of 28.6 days. During the treatment, radiographic examination showed that narrowing, irregular contour, and various ulcers of the colon were reversed, at least in part, in all cases, although there was no improvement in the strictured lesions of 2 cases, who finally underwent surgical intervention. The colonic changes were further improved in 4 of the 5 cases who received radiographic examinations of the colon from 18 to 58 months (average 32.2 months) after TPN was discontinued. The present study suggests that treatment with TPN for Crohn's disease is not only beneficial for clinical symptoms but also improves radiographic and endoscopic changes of the colonic lesions except for stricture.

Adolescent↗