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Biomedical subjects

H Chai

Publications and source records attributed to H Chai.

At least 19 recordsLinked to original sources
PubMed1992

[Effects of adrenergic agonist on population spike in CA1 region of hippocampal slices from partial and full kindled rats].

Effects of adrenergic agonist on population spike (PS) amplitude were studied extracellularly at CA1 region of hippocampal slices from partial and full kindled rats with coriaria lactone (1-1.25 mg/kg, two days a time, i.m.) and compared with those from control rats. 5 mumol/L norepinephrine (NE) increased PS; 50 mumol/L NE decreased it slightly. 5 mumol/L isoproterenol (ISO) increased PS. 100 mumol/L phenylephrine (PE) decreased it. The effects of increasing and decreasing PS could be antagonised by beta and alpha adrenergic antagonists, respectively. The effects of NE and PE on PS amplitude showed no significant difference between the control and kindled rats. The effect of beta-adrenergic agonist ISO on PS amplitude in hippocampal slices from partial kindled rats was less than that of control (P < 0.01). The effect of ISO on PS of full kindled rats was partially recovered.

Animals↗
PubMed1992

[Effects of calcium channel blocker verapamil on hippocampal kindled seizures induced by coriaria lactone in rabbits].

Eighteen fully kindled rabbits, whose epilepsy had been produced by intrahippocampal (i.h.) injections of 2 microliters of diluted solution containing 0.32 or 0.55 micrograms of coriaria lactone (CL), were separated into three groups. One of them was used as the control group. For seizure, all animals were given CL (0.6-1 micrograms/2 microliter i.h.). Ten minutes later, the verapamil (VR) group of six rabbits was treated with VR (1.5 or 2 mg/kg i.m. 2.5 or 5 micrograms/2 microliters i.h.); the normal saline (NS) group (six rabbits) received 0.8 ml/kg (i.m., in the same volume as that of the VR 2 mg/kg injection) or 2 microliters (i.h.) of NS; the control group of six received neither VR nor NS. The experiments were made once every eight days. Hippocampal EEGs of all animals were recorded by telemetric method and their behavior after injection was observed continuously in 4-7 hours. The results of the experiment indicated that the i.h. administration of 2.5 or 5 micrograms/2 microliters of VR is effective on hippocampal kindled seizures induced by CL in rabbits, but the curative effects of the i.m. administration of 1.5 or 2 mg/kg of VR were less notable than those of the i.h. administration.

Animals↗
PubMed1992

[Observation of paired-pulse depression in CA1 region of hippocampal slices from coriaria lactone-kindled rats].

Paired-pulse depression (PPD) technique was used to investigate the potency of recurrent synaptic inhibition mediated by GABA in area CA1 of 54 hippocampal slices from coriaria lactone (CL)-kindled and control rats. When paired stimuli were sent to the axon of CA1 pyramidal cell and Schaffer collaterals, the effect of population spike PPD lasted about 40-60ms; no significant change was observed on PPD potency between kindled and control groups (P = 0.06, 2-way ANOVA). The results indicate that the GABA-ergic synaptic inhibition seemed not to play a key role in the maintenance of the chemical kindling induced by CL.

Animals↗
PubMed1979

Effects of relaxation training on pulmonary mechanics in children with asthma.

An experiment, designed to overcome shortcomings in previous work, was conducted to investigate the potential symptomatic benefits of relaxation training in the treatment of asthma in children. Fourteen chronic, severely asthmatic children received three sessions in which they rested quietly, followed by five sessions of relaxation training, and finally three sessions of relaxing as trained previously. Pulmonary function was assessed, in a manner far more definitive than in previous studies, before and after each session, and three additional times at 30-minute intervals thereafter. Tension in the frontales muscles, heart and respiration rates, and skin temperature and conductance were also monitored. Heart rate and to some extent muscle tension results tended to confirm the attainment of relaxed states. However, the lung function results failed to substantiate the previous, preliminary findings of a clinically meaningful change in pulmonary function following relaxation. The status of relaxation in the treatment of asthma was discussed.

Adolescent↗
PubMed1979

Airway cooling. Stimulus for exercise-induced asthma.

Five patients were studied using a randomly assigned sequence of four inspired-air conditions during strenuous treadmill exercise for 10 min. The four inspired-air conditions were: (1) Cool, dry room air (CDA) at 23 degrees C with 3 mg of water and 7.3 cal of heat content/l, (2) over-saturated air (OSA) at room temperature containing 43 mg water and 16.3 cal/l, (3) hot, dry air (HDA) at 120 degrees C having 3 mg water and 24.4 cal/l, and (4) warm, humidified air (WHA) at 37 degrees C with 43 mg water and 34.7 cal/l. Using inspired-air CDA and OSA, all patients manifested exercise-induced asthma (EIA) while forced expiratory volume in 1 sec (FEV1) and maximal mid-expiratory flow (MMEF) decreased to an average of 81% and 63% of the baseline when breathing CDA and to 83% and 71% of the baseline when breathing OSA. With WHA, EIA was clearly prevented while the post-exercise FEV1 and MMEF were 101% and 103% of baseline, respectively. With HDA, the post-exercise FEV1 and MMEF were 95% and 86% of baseline, respectively. Analysis of variance revealed that the post-exercise pulmonary function changes had resulted solely from respiratory heat loss and not from water loss or from interaction of heat and water losses. These results indicate that exercise-induced asthma is associated with airway cooling incurred during exercise rather than airway dehydration.

Adolescent↗
PubMed1978

Altered theophylline pharmacokinetics during acute respiratory viral illness.

The plasma half-life of theophylline was determined during and 1 month after serologically confirmed upper-respiratory-tract viral illness in six children with chronic asthma. In this group the plasma-theophylline half-life (mean = 419.8 min) was significantly longer during the acute stage of their illness than 1 month later (mean 249.9 min). There was no appreciable change in half-life in 4 patients who were febrile but in whom seroconversion did not occur. These preliminary results suggest that certain upper-respiratory-tract viral infections may affect theophylline metabolism.

Acute Disease↗
PubMed1978

Irreversibility of obstructive changes in severe asthma in childhood.

The findings in three children with severe asthma are presented. Following intensive round-the-clock therapy with theophylline (the dosage of which maintained serum levels of theophylline between 10 microgram/ml and 20 microgram/ml) and therapy with prednisone (20 mg twice daily for three weeks or more), there were improvements in spirometric and body plethysmographic measurements. Despite this therapy, abnormalities in the forced expiratory volume in one second, the maximal midexpiratory flow, the residual volume, and specific airway conductance remained. These cases represent a subgroup of asthmatic children with reactive airways who have an irreversible component to their disease.

Adolescent↗
PubMed1978

Age of onset in a group of severely asthmatic children.

The age of onset was examined retrospectively in a group of severely asthmatic children. The mean age of onset for males was 29.4 +/- 22.7 months and 30.4 +/- 27.0 months for females. The distribution of age of onset between males and females was remarkably similar (X2 = 1.77, 0.6 less than p less than 0.9). The mean age of onset was similar in children not receiving corticosteroids compared to those children who were taking high and low dose corticosteroids. An early or late age of onset appeared independent of corticosteroid requirements. Children with five or more positive immediate skin tests had earlier age of onset and higher total serum IgE levels than those with four or fewer positive skin tests.

Age Factors↗
PubMed1977

Alpha-1 antitrypsin in childhood asthma.

Alpha-1 antitrypsin (AAT) phenotypes and serum levels were studied in two childhood perennial asthmatic populations. The first was an ambulatory, mostly mild nonsteroid-dependent group living in Rochester, N.Y. The second was a more severe mostly steroid-dependent group residing at an asthma residential treatment center in Denver, Colo. The prevalences of alpha-1 antitrypsin protease inhibitor (Pi) tyes were the same for bothe groups and similar to prevalences in a random population. Alpha-1 antitrypsin serum levels were significantly elevated for the mild nonsteroid-dependent group when compared to the more severe steroid-dependent group. The steroid-dependent group had serum levels similar to a group of nonasthmatic control children. These findings indicate that there is not a strong association of alpha-1 antitrypsin Pi variants such as Pi MZ or Pi MS with more severe asthma. Elevated serum levels in the milk perennial asthmatic group may be the result of chronic inflammatory processes. Normal levels in the sterioid-dependent group may be the result of corticosteroid control of inflammation associated with asthma.

Adolescent↗