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M T Lin

Publications and source records attributed to M T Lin.

At least 37 records · Page 2Linked to original sources
PubMed1992

Effects of intra-raphe injection of amino acids on cardiovascular function in rats.

The effects of microinjection of an excitatory amino acid (glutamate, 10 micrograms) or several inhibitory amino acids (taurine 10 micrograms, GABA 10 ug or glycine 10 ug) into the dorsal raphe region on cardiovascular function were assessed in rats under pentobarbital sodium. Intra-raphe administration of glutamate, but not saline, caused an increase in the mean arterial pressure. By contrast, intra-raphe administration of taurine, GABA or glycine, but not saline, caused a decrease in both the mean arterial pressure and the heart rate. The glutamate-induced hypertension or both the hypotension and the bradycardia induced by taurine, GABA or glycine was antagonized by pretreatment with intra-raphe injection of a serotonergic receptor antagonist (1 ug cyproheptadine). In addition, the vasopressor and bradycardia responses to an intravenous dose of epinephrine (2.5 ug/kg) were assessed in saline-treated rats and amino acid-treated rats. Intra-raphe injection of glutamate produced a significant decrease in reflex bradycardia compared to the controls. On the other hand, administration of taurine, GABA or glycine into the dorsal raphe region led to an enhancement of epinephrine-induced bradycardia. Again, the reduction or the facilitation of the epinephrine-induced bradycardia following administration of these amino acids was antagonized by pretreatment with cyproheptadine. The results suggest that the serotonergic receptor mechanisms in the dorsal raphe region play a role in the elaboration or modulation of the cardiovascular responses to amino acids (including glutamate, taurine, GABA and glycine).

Amino Acids↗
PubMed1991

Insulin acts on the hypothalamic glucose-facilitated neurons to induce hyperglycemia and hyperinsulinemia in the rat.

Microinjection of insulin (0.04-0.12 IU/microliter) into the anterior hypothalamus or the lateral hypothalamus, but not the ventromedial hypothalamus of the rat brain, caused a dose-dependent rise in blood glucose and in serum insulin. The majority (71.5%) of the glucose-facilitated neurons recorded in the lateral hypothalamic area were excited by intracerebral injection of insulin. The data indicate that insulin acts on the hypothalamic glucose-facilitated neurons to induce hyperglycemia and hyperinsulinemia. It is unknown whether insulin normally reaches the hypothalamic area, or how it might do so.

Animals↗
PubMed1991

Pyrogenicity of polyadenylic.polyuridylic acid in rabbits.

Polyadenylic.polyuridylic acid injected intravenously into rabbits produced a rapid-onset, monophasic fever. Pyrogenic tolerance occurred in rabbits following daily injections of polyadenylic.polyuridylic acid. However, direct injection of the agent into the preoptic anterior hypothalamic region of rabbit's brain produced a markedly different fever. After an intrahypothalamic injection of polyadenylic.polyuridylic acid, fever was delayed in onset and persisted for a longer period. At room temperature, the fever was due to both increased metabolism and cutaneous vasoconstriction. In a colder atmosphere the fever was due solely to increased metabolism, whereas in the heat the fever was due to reduction in cutaneous blood flow and respiratory evaporative heat loss. In addition, the fever induced by intravenous polyadenylic.polyuridylic acid injection was reversed by a cyclooxygenase inhibitor, but not by a protein synthesis inhibitor. Polyadenylic.polyuridylic acid was shown to stimulate PGE2 production from rabbit's hypothalamus in vitro. The results reveal that this agent is a prostaglandin-dependent pyrogen.

Animals↗
PubMed1991

Stimulation of 5-hydroxytryptamine nerve cells in dorsal and median raphe nuclei elevates blood glucose in rats.

The role played by dorsal or median raphe nuclei in glucoregulation was investigated by stimulating these nuclei in normal rats and in rats with chemical ablation of the hydroxytryptamine (5-HT) nerve cells in these nuclei. Electrical stimulation of either dorsal or median raphe nuclei increased blood glucose or the in vivo voltammetric signal of hypothalamic 5-OH-indole in normal rats; the increase in blood glucose level or the hypothalamic 5-OH-indole release was proportional to the intensity of stimulation. Microinjection of kainic acid or L-glutamate at the same sites also produced hyperglycemia or stimulated the hypothalamic 5-OH-indole release. This stimulation-induced hyperglycemia was significantly reduced by pretreatment of animals with spinal transection or adrenalectomy. In addition, selective destruction of the hypothalamic 5-HT nerve fibers, produced by administration of 5,7-di-hydroxytryptamine (a 5-HT nerve depletor) into both dorsal and median raphe regions, reduced the magnitude of the hyperglycemic responses to electrical stimulation of either dorsal or median raphe nuclei. The data indicate that stimulation of ascending 5-HT pathways in the rat's brain increases the adrenal-sympathetic efferent activity and leads to hyperglycemia.

Animals↗
PubMed1991

The fever induced by polyriboinosinic:polyribocytidylic acid is not related to interferon synthesis in the rabbit's hypothalamus.

We previously demonstrated that direct administration of interferon (IFN) or its inducer polyriboinosinic acid:polyribocytidylic acid [poly(I:C)] into the hypothalamus caused dose-dependent fever in rabbits. It was not clear whether the fever induced by intrahypothalamic injection of poly(I:C) was due to stimulation of IFN or prostaglandin E-2 synthesis in the hypothalamic tissues. Therefore, in the current experiments, we used an established model in which rabbit hypothalamic minces or brain cells were incubated in vitro with poly(I:C) to test for the ability of poly(I:C) to stimulate IFN or PGE-2 synthesis. The results showed that poly(I:C) stimulated PGE-2, but not IFN, synthesis in the hypothalamus. Thus, it appears that the fever induced by poly(I:C) is not related to IFN synthesis in the hypothalamus.

Animals↗
PubMed1990

bcr rearrangements in Philadelphia chromosome-positive acute lymphoblastic leukemia. A study of five Chinese patients in Taiwan.

Cytogenetic studies were successfully conducted on 73 Chinese patients with acute lymphoblastic leukemia (ALL). A Philadelphia chromosome (Ph) was identified in four (9%) of the 46 children and in four (15%) of the 27 adults. None of these patients had any clinical features suggestive of chronic myelogenous leukemia (CML). Leukemic cells from five of the eight Ph-positive (Ph+) ALL patients were analyzed for bcr rearrangement by Southern blot analysis with three restriction enzymes and two bcr probes. One of the three children and both adult patients studied showed bcr rearrangement. Based on the data from the literature and the present study, 58% of adult and 14% of childhood Ph+ ALL patients demonstrated bcr rearrangement. There were no significant differences in clinical or laboratory findings between the two groups of patients with or without bcr rearrangement. Patients who had Ph+ ALL but no bcr rearrangement appear to have been victims of de novo acute leukemia, but it was still difficult to determine whether patients with bcr rearrangement had acute lymphoid transformation of subclinical CML. More studies and longer follow-ups are needed for clarification.

Adolescent↗
PubMed1990

Paramedian reticular nucleus: a thermolytic area in the rat medulla oblongata.

The effects of stimulation or ablation of the paramedian reticular nucleus (PRN) of the rat medulla oblongata on the thermal responses induced by ambient temperature changes, a pyrogen, or a hypothermic substance were assessed. Electrical stimulation of the PRN elicited thermolytic reactions (including decreased metabolism, cutaneous vasodilation and hypothermia) which could be mimicked by micro-injection of kainic acid (an excitotoxic amino acid) into the same region. Bilateral electrolytic lesions in the PRN prevented the animals from responding to heat stress (35 degrees C for 30 min) to some extent, but did not prevent responses to cold stress (4 degrees C for 60 min). In addition, the thermogenic reactions induced by intrahypothalamic injection of polyriboinosinic acid: polyribocytidylic acid (a pyrogenic substance), or the thermolytic reactions induced by intraperitoneal administration of chlorpromazine (a tranquilizer), were antagonized respectively by activation or ablation of the PRN. This suggests that the PRN of the caudal medulla may function as a thermolytic area.

Animals↗
PubMed1990

Stimulation of a bulbospinal 5-HT pathway in the rat brain produces hyperglycaemia.

The glucoregulatory role of spinally projecting serotonin (5-HT) neurones near the ventrolateral surface of the medulla oblongata was investigated by stimulating these nerve cells in normal rats and in rats with selective chemical ablation of 5-HT nerves in the spinal cord. Electrical stimulation of the lateral medulla produced hyperglycaemia in normal rats; the increase in blood glucose was proportional to the intensity and frequency of stimulation. Furthermore, microinjection of kainic acid or L-glutamate at the same sites also produced hyperglycaemia. This stimulation-induced hyperglycaemia was significantly reduced by spinal transection or adrenalectomy. Selective destruction of spinal 5-HT nerves produced by intraspinal injection of 5,7-dihydroxytryptamine also reduced the magnitude of the hyperglycaemia response to electrical stimulation of the lateral medulla. This indicates that stimulation of 5-HT nerve cells adjacent to the ventrolateral surface of the medulla oblongata and projecting to the spinal cord increases the adrenal-sympathetic efferent activity and leads to hyperglycaemia in rats.

5,7-Dihydroxytryptamine↗
PubMed1990

Febrile effects of polyriboinosinic acid: polyribocytidylic acid and interferon: relationship to somatostatin in rat hypothalamus.

The changes in thermoregulatory effectors produced by an injection of polyriboinosinic acid: polyribocytidylic acid (Poly I:C) or interferon were assessed and compared in control rats, in rats with hypothalamic somatostatin (SS) receptor blockade and in rats with hypothalamic SS depletion. Intrahypothalamic (i.h., 0.05-0.50 microgram) or intraperitoneal (i.p., 100-600 micrograms) administration of Poly I:C caused a dose-related rise in colon temperature in control rats at all ambient temperatures (Ta) studied. A Poly I:C-induced fever was produced by increased metabolism at a Ta of 8 degrees C, whereas at 30 degrees C, it was caused by cutaneous vasoconstriction. At a Ta of 22 degrees C, the fever was caused by increased metabolism and cutaneous vasoconstriction. On the other hand, i.h. administration of SS-14 antagonist (0.1-0.5 ng) caused a dose-related fall in colon temperature at Ta of 8 degrees C or 22 degrees C. At a Ta of 8 degrees C, the hypothermia was caused by decreased metabolism, whereas at 22 degrees C, it was caused by decreased metabolism and cutaneous vasodilation. At a Ta of 30 degrees C, the thermoregulatory effectors were not affected by SS-14 antagonist treatment. Furthermore, the fever induced by Poly I:C or interferon was significantly reduced by pretreatment of rats with an i.p. dose of cysteamine (30 mg. kg-1) or an i.h. dose of SS-14 antagonist (0.1 ng). The results indicate that a somatostatinergic pathway in rat hypothalamus may mediate the fever induced by interferon or its inducer Poly I:C.

Animals↗
PubMed1990

Cholinergic mechanisms in the rat's hypothalamus mediate the stimulatory effect of thyrotropin-releasing hormone on gastric secretion.

To assess the possible involvement of cholinergic mechanisms in the hypothalamic nuclei in the stimulatory effect of TRH on gastric secretion, rats were infused with thyrotropin-releasing hormone (TRH), cholinergic agonist or antagonist, and normal saline through previously implanted hypothalamic cannulae. Administration of TRH or pilocarpine into the lateral cerebral ventricle or the anterior hypothalamus caused a dose-related increase in gastric volume and acidity in rats. On the other hand, administration of either atropine or D-tubocurarine into the same brain sites caused the opposite effects. Furthermore, the stimulatory effect of TRH or pilocarpine on gastric secretion was completely abolished by pretreatment of the CSF or the anterior hypothalamus with atropine and to a lower degree, D-tubocurarine. Administration of TRH, pilocarpine, atropine or D-tubocurarine into the lateral hypothalamus produced only a slight effect on gastric volume and acidity. However, the gastric volume or acidity was not affected by administration of either TRH, pilocarpine, atropine or D-tubocurarine into the ventromedial hypothalamus in our rats. The data indicate that the cholinergic muscarinic receptor mechanisms in the anterior hypothalamus may mediate the stimulatory effect of TRH on gastric secretion in rats.

Animals↗
PubMed1990

Effects of organogermanium compound 2-carboxyethyl germanium sesquioxide on cardiovascular function and motor activity in rats.

In rats anesthetized with urethane, intraperitoneal administration of a water-soluble organogermanium compound 2-carboxyethyl germanium sesquioxide (Ge-132) produced a dose-related reduction in either the mean arterial pressure or the heart rate. Both hypotension and bradycardia responses induced by Ge-132 injection were significantly inhibited by pretreatment of the animals with either spinal transection or bilateral vagotomy. The data indicate that Ge-132 induces both hypotension and bradycardia by promoting an activation of the parasympathetic efferent mechanisms and an inhibition of the sympathetic efferent mechanisms. On the other hand, following intraperitoneal injection of Ge-132, increased grooming and head swaying (as shown by an enhancement in fine movements monitored by an electronic activity counter) were provoked. Furthermore, the amphet-amine-induced enhancement in fine movements was potentiated by pretreatment of the animals with Ge-132. Thus, it appears that Ge-132 acts through the catecholaminergic mechanisms in the brain to induce locomotor stimulation in rats.

Amphetamine↗
PubMed1990

Delayed erythropoiesis after major ABO-incompatible bone marrow transplantation: report of a case.

Major ABO-incompatible bone marrow transplantation (BMT) may be associated with delayed erythropoiesis. A 38-year-old man (blood group O) with chronic myelogenous leukemia received a BMT from his histocompatibility antigen (HLA) identical brother (blood group A). The pre-BMT anti-A titer of the patient was 1:4. The harvested marrow was depleted of RBC by 6% hydroxyethyl starch sedimentation and Ficoll-Hypaque gradient centrifugation. No acute hemolysis occurred after marrow infusion. Myeloid and megakaryocytic series engrafted promptly. However, delayed erythropoiesis up to day 266 was found. Prolonged presence of anti-A antibody was noted for more than 250 days after BMT, although the peak titer was only 1:8. After the reconstitution of bone marrow, the erythroid series was confirmed as donor origin (RBC cell typing A). It is proposed that the prolonged presence of anti-A antibody probably produced from the residual host B lymphocytes, would destroy the regenerating erythroid precursors. Also, use of cyclosporin A may be associated with higher rates of prolonged production of anti-A/B antibodies and the subsequent delayed erythropoiesis.

ABO Blood-Group System↗
PubMed1990

Decentralization of superior cervical ganglia attenuates heat stroke formation in rabbits.

The effects of preganglionic decentralization of (sympathetic trunk resection) or post-ganglionic excision (ganglionectomy) of the superior cervical ganglia on cerebral blood flow and the formation of heat stroke were assessed in rabbits. An intravenous isotope method for external measurement of cerebral circulation time was applied to rabbits for determining cerebral blood flow. Heat stroke was induced by exposing animals to a high ambient temperature of 40 degrees C. The occurrence of loss of sensation, decreased muscle tone and unconsciousness was taken as the onset of heat stroke. The results showed that decentralization of the superior cervical ganglia enhanced the cerebral blood flow, whereas ganglionectomy reduced the cerebral blood flow. In addition, the latency for the onset of heat stroke and the survival time after the heat stroke were greatly prolonged by the former surgical procedure, but shortened by the later one. The data suggest that decentralization of the superior cervical ganglia attenuates formation or development of heat stroke by promoting an increase in cerebral blood flow in rabbits.

Animals↗