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Biomedical subjects

C Y Chiang

Publications and source records attributed to C Y Chiang.

At least 55 records · Page 3Linked to original sources
PubMed1990

Effect of unilateral vagotomy on capsaicin-induced neurogenic inflammation in the trachea of rats.

This study reports the effect of unilateral vagotomy on neurogenic inflammation in the trachea. Neurogenic inflammation was produced in the trachea of vagotomized rats by a venous injection of capsaicin, the pungent ingredient of red pepper. Monastral blue was used as tracer dye to label the affected blood vessels. Vagus nerves and tracheal tissues were processed for light and electron microscopy. The damaged right vagus nerve was found to have degenerated. However, unilateral vagotomy did not completely block neurogenic inflammation in the trachea ipsilaterally and contralaterally, as shown in the whole mount preparations. Microscopic observations of tracheal tissue sections showed that neurogenic inflammation did not evenly occur on both sides of the trachea. The possible reason for this is discussed.

Animals↗
PubMed1989

Inhibitory effect of stimulation of the anterior pretectal nucleus on the jaw-opening reflex.

The anterior pretectal nucleus (APT) has been recently implicated in sensorimotor integration and has been shown to have suppressive influences on tail flick behaviour and on nociceptive responses of spinal dorsal horn neurones in rats. The present study tested the effect of stimulation of the APT on the rat's digastric jaw-opening reflex elicited by orofacial stimuli. Either ipsilateral or contralateral electrical stimulation at histologically confirmed sites within and immediately subjacent to the APT produced a suppression of the reflex that had an onset of 20-30 ms, peaked around 50 ms and lasted for 200-300 ms; in some cases, a brief period of reflex facilitation preceded the onset of inhibition and the inhibition was sometimes followed by a facilitatory period. No prolonged period of suppression induced by electrical stimulation was noted in these anaesthetized rats. The injection of monosodium glutamate at comparable sites within and subjacent to APT induced reflex suppression that lasted several minutes. These findings represent the first documentation of APT-induced modulation in the trigeminal sensorimotor system, but support recent evidence suggesting the involvement of APT in sensorimotor integration and modulation.

Animals↗
PubMed1989

Changes in mechanoreceptive field properties of trigeminal somatosensory brainstem neurons induced by stimulation of nucleus raphe magnus in cats.

Experiments were carried out on adult anesthetized cats in which the effects of nucleus raphe magnus (NRM) conditioning stimulation (20 ms) were tested on the responses evoked by orofacial stimuli in single brainstem neurons of trigeminal (V) subnucleus oralis. The NRM stimulation induced inhibition of the responses of 57 of 77 low-threshold mechanoreceptive (LTM) neurons and the one wide-dynamic range (WDR) neuron tested. The duration of the neuronal inhibition ranged from 300-600 ms and the mean threshold for inhibition ranged from 47.8 +/- 4.8 to 102.7 +/- 15 microA depending on the orofacial stimulation site (skin or tooth pulp) and form (mechanical or electrical) of cutaneous stimuli used to evoke neuronal responses. In 20 LTM neurons showing NRM-induced inhibition that were specifically examined for the effects of NRM stimulation on the mechanoreceptive field, one population (n = 11) showed shrinkage (mean 55 +/- 4.4% from control area) of the mechanoreceptive field while the remaining neurons (n = 9) showed no change in mechanoreceptive field size during NRM stimulation. The former group of neurons were also distinguished from the latter neurons by their significantly larger mechanoreceptive field and the activation of the majority of them by electrical stimuli applied outside their mechanoreceptive field. The responses of these neurons evoked by low-threshold inputs from the edge of the mechanoreceptive field were more sensitive to NRM conditioning stimulation than responses evoked from the mechanoreceptive field center, as judged by threshold, magnitude and duration of the NRM-induced inhibition. These findings underscore the sensitivity of LTM neurons to NRM influences. They also reveal a particular population of oralis neurons which have a differential sensitivity of low-threshold inputs evoked from the edge compared to the center of the mechanoreceptive field.

Action Potentials↗
PubMed1989

Evidence for the involvement of a descending cholinergic pathway in systemic morphine analgesia.

The analgesic effect of morphine sulfate (3-5 mg/kg, i.p.) was assessed by both tail-flick and hot-plate tests in unanesthetized restrained rats. Intrathecal administration of atropine sulfate (10 micrograms) in the lumbar region of the spinal cord powerfully reduced the analgesia induced by systemic administration of morphine. This action did not result from the diffusion of atropine from its administration site to more rostral sites in the central nervous system. In spinal rats, atropine failed to reverse morphine analgesia, thus strongly suggesting that either a cholinergic descending pathway or a spinal local cholinergic circuit activated by an unknown descending pathway may be involved in the systemic morphine analgesia. In addition, the involvement of the alpha-adrenergic descending pathway in morphine analgesia is confirmed, whereas that of the serotonergic descending pathway is less prominent.

Analgesia↗
PubMed1989

[Laryngeal tuberculosis simulating epiglottitis--a case report].

Adult epiglottitis is an otolaryngological emergency. Under proper antibiotic therapy, however, most cases recover rapidly. This is a report of a case in which clinical findings indicated acute epiglottitis, but which showed no improvement with antibiotic therapy when treated by a local medical doctor for three weeks. Following the immediate application of a fiberoptic and microscopic direct laryngoscope with biopsy, an accurate diagnosis was established, i.e. laryngeal tuberculosis. After receiving the appropriate antituberculous therapy for just one week, the patient's symptoms improved dramatically.

Acute Disease↗
PubMed1988

Thymolipoma in patients with myasthenia gravis: report of two cases and review.

Two cases of simultaneous occurrence of myasthenia gravis (MG) and thymolipoma are described and 4 previously reported cases are reviewed. In all 6 cases, thymectomy was performed. Pre- and postoperatively, the clinical status of the patients was similar to that of late-onset MG without thymolipoma. It is possible that simultaneous occurrence of MG and thymolipoma may be coincidental.

Azathioprine↗
PubMed1987

Does morphine enhance the release of 5-hydroxytryptamine in the rat spinal cord? An in vivo differential pulse voltammetry study.

Differential pulse voltammetry used in combination with an electrochemically treated carbon fiber electrode allowed the detection of 5-hydroxyindoles (5-HI) in the dorsal horn of the urethane-anesthetized rat. Voltammograms were recorded every 3 min for up to 4 h. One component of the signal, peak 3, corresponding to 5-HI and uric acid was first identified separately in vitro as well as in vivo, and then further examined by means of systemic L- and D-trytophan administration and by local application of uricase, respectively. It was found that the height of peak 3 was unaffected by systemic morphine. Even following pretreatment with probenecid, the height of peak 3 was increased only 8.6-13.7% over that with saline, by morphine given either intraperitoneally or intracerebrally into the nucleus raphe magnus. However, these increments of peak 3 were not statistically significant. These findings suggest that the serotonin descending system is unlikely to play an important role in morphine analgesia.

Animals↗
PubMed1986

Responses of serotonergic and non-serotonergic neurons in the rat nucleus raphe magnus to systemic lysergic acid diethylamide.

Serotonergic and non-serotonergic neurons in the nucleus raphe magnus were identified by conduction velocities and spontaneous discharge rates. Eight of 13 serotonergic neurons were depressed by lysergic acid diethylamide (LSD) administration (40-50 micrograms/kg, i.p. or i.v.), while the others were non-responsive. Among 38 non-serotonergic neurons, 5 were depressed, 4 were excited and 29 were unaffected by systemic LSD at the same doses. It is thus concluded that LSD could act differently on serotonergic and non-serotonergic neurons in nucleus raphe magnus.

Action Potentials↗
PubMed1985

Differential responses of serotonergic and non-serotonergic neurons in nucleus raphe magnus to systemic morphine in rats.

Forty-eight raphe-spinal units in nucleus raphe magnus were identified by antidromic stimulation and further classified into serotonergic and non-serotonergic populations according to their conduction velocity and spontaneous discharge rate. Following morphine administration (5 mg/kg, i.p.) they showed different responses: excitatory, depressive or non-responsive. It was found that 6 of 7 non-responsive, 3 of 20 depression-responsive and only 1 of 21 excitation-responsive units proved to be serotonergic neurons, indicating that the involvement of serotonergic neurons in morphine analgesia is probably insignificant. It is suggested that the raphe-spinal fiber systems, both excitatory and inhibitory are originated mainly from the non-serotonergic neurons.

Animals↗
PubMed1984

In vivo electrochemical detection of 5-hydroxyindoles in rat cerebral cortex and spinal cord: differential effects of p-chloroamphetamine, probenecid and clorgyline.

Differential pulse voltammetry associated with carbon fiber microelectrodes was used to detect the 300 mV signal which is known to reflect the concentration of 5-hydroxyindoles in the spinal cord and cerebral neocortex of rats anesthetized with urethane or chloral hydrate. The intraperitoneal injection of p-chloroamphetamine resulted in an increase in the amplitude of the signal in the neocortex but not in the spinal cord. Administration of clorgyline did not consistently modify the signal monitored in the neocortex whereas it decreased in the spinal cord. Probenecid induced a larger increase in 5-hydroxyindoles in the neocortex than in the spinal cord. These results demonstrate that different parts of the serotonergic system might be differentially sensitive to drugs affecting serotonin metabolism.

Amphetamines↗
PubMed1983

Differential pulse voltammetry in the dorsal horn of the spinal cord of the anesthetized rat: are the voltammograms related to 5-HT and/or to 5-HIAA?

Treated carbon fiber microelectrodes were used with the differential pulse voltammetry method for in vitro and in vivo determination of indoleamines. Under these conditions a peak of oxidation current which is characteristic of 5-hydroxyindoles is recorded at 280-300 mV. Treated carbon fiber microelectrodes respond in vitro linearly over a large range of concentrations of 5-hydroxytryptamine (5-HT) and of 5-hydroxyindoleacetic acid (5-HIAA), but are 5-8 times more sensitive to 5-HT than to 5-HIAA. In vivo, the question remains as to the exact nature of the peak because the oxidation potentials of 5-HT and 5-HIAA are close together and cannot be monitored separately. Pharmacological investigations were hence carried out in order to characterize the electrochemical signal detected at 300 mV in the dorsal horn of the lumbar spinal cord of chloral hydrate-anesthetized rats. Using 250 micron long carbon fiber microelectrodes, the electrochemical signal stabilizes at 30-90 min and the peak remains constant for up to 210 min. Administration of the monoamine oxidase inhibitor (MAOI) clorgyline produced a progressive decrease of the signal which reached a decrease of 33% of control at 180 min after injection. At this time biochemical measures demonstrated a 117% increase in 5-HT and a 32% decrease in 5-HIAA in the dorsal half of the spinal cord. Reserpine provoked an increase of 20% in the electrochemical peak and the 5-HIAA outflow blocker probenecid gave rise to a sustained plateau of about 60% above control values.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Increase of serotonin metabolism within the dorsal horn of the spinal cord during nucleus raphe magnus stimulation, as revealed by in vivo electrochemical detection.

Carbon fiber microelectrodes were used with the differential pulse voltammetry method for in vivo determination of indolamines within the extracellular space of the dorsal horn of the spinal cord or chloral hydrate-anesthetized rats. Under these conditions a peak of oxidation current which is characteristic of 5-hydroxyindoles is recorded at 280-300 mV. Stimulation of the nucleus raphé magnus (NRM) with stimulation parameters comparable to those used to elicit analgesia in freely moving animals produced marked alterations in the voltammograms: (1) stimulation of the NRM for 10 min induced an immediate and sustained increase in the peak amplitude; (2) post-effects of variable duration were observed; (3) the increase in the 5-hydroxyindolaminergic signal was significantly reduced during a second series of NRM stimulations indicating some degree of tolerance to central stimulation. The accuracy of these observations is strengthened by the fact that the basal 5 hydroxyindolaminergic signal is strongly depressed after pretreatment of the animal with p-chlorophenylalanine; in addition, under these conditions, NRM stimulation is totally inefficient. We suggest that these results reflect the in vivo modification of 5-HT metabolism. This represents the first evidence for an in vivo release of 5-HT during stimulation of brain stem areas which induces powerful analgesia in freely moving animals.

Animals↗
PubMed1975

Effects of delta-9-tetrahydrocannabinol on mouse spleens.

A study was undertaken to ascertain the effects of delta-9-Tetrahydrocannabinol on the plaque forming cell response of mice immunized with sheep erythrocytes. It was found that a marked suppression of plaque forming cells occurred concomitant with a general loss of spleen cellularity following administration of delta-9-THC. These results suggest rather marked effects of this drug on antibody synthesis.

Animals↗
PubMedDate not supplied

Hepatitis B vaccine in hemodialysis patients with hepatitis C viral infection.

Patients on hemodialysis therapy are at a relatively high risk of exposure to hepatitis B virus (HBV) infection. The prevalence of hepatitis C virus (HCV) infection is even higher and was reported as 33.2% in Taiwan. Although the efficacy of hepatitis B vaccine was well documented, the vaccination schedule in hemodialysis patients is not clearly defined. And under such a high prevalence of HCV infection, little is known about the influence of HCV imposing on HBV vaccination. We studied 50 chronic hemodialysis patients who were serologically negative for the hepatitis B surface antigen (HBsAg), the antibody to the hepatitis B surface antigen (anti-HBs) and the antibody to the hepatitis B core antigen (anti-HBc); 26 of them were positive for the antibody to hepatitis C virus (anti-HCV) test. Recombinant hepatitis B vaccine (Engerix-B) 40 micrograms per dose was administered by the intramuscular route at deltoid region at 0, 1, 2, 6 and 12 months respectively to all the patients. Forty-six patients had completed the study. The effective seroconversion rate (serum anti-HBs titer > 10 mIU ml-1) at 1 month after the final vaccine was 76.1% (35/46). The effective conversion rates of the anti-HCV(+) group to the anti-HCV(-) were 75% versus 77.3% (P = 0.857). Geometric mean anti-HBs titers were 177.67 mIU ml-1 versus 189.28 mIU ml-1 (P = 0.867). Our results showed that five-dose injections of HBV vaccine do not present a superior outcome to the four-dose regimen comparing to published data. The status of positivity of anti-HCV do not pose an suboptimal effect on HBV vaccination of hemodialysis patients.

Adult↗