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Biomedical subjects

Z S Huang

Publications and source records attributed to Z S Huang.

At least 19 recordsLinked to original sources
PubMed1995

Impact of alcohol consumption and cigarette smoking on stroke among the elderly in Taiwan.

BACKGROUND AND PURPOSE: We investigated the influence of alcohol consumption and cigarette smoking on all types of stroke and cerebral infarction, in particular among a representative sample of elderly residents in Taiwan. METHODS: This study was a component of a nationwide survey of health and living status of residents aged 65 years or older in Taiwan in which subjects received detailed physical, neurological, and laboratory examinations. Inquiries were made about medical history, and information on the amount and duration of drinking and smoking was obtained. Diagnoses of stroke were made according to the results of brain computed tomography at the onset of disease or were based on criteria established by the World Health Organization. RESULTS: Of the 2600 subjects, there were 155 elderly persons with stroke (prevalence, 6%). Excessive drinking of more than 367.6 g/wk of alcohol was associated with a high prevalence of cerebral infarction. Consumption of < or = 367.5 g/wk of alcohol did not have an influence on stroke prevalence. The relationship between duration of alcohol drinking and stroke was equivocal. More than 30 pack-years of cigarette smoking was a significant risk factor for all types of stroke and cerebral infarction in particular. Using multiple logistic regression to control for possible confounders, it was found that smoking was an independent risk factors for all stroke and was of borderline significance for cerebral infarction. Although excessive drinking was a significant risk factor for cerebral infarction in univariate analysis, this effect was lost after adjustment for other confounders. CONCLUSIONS: Cigarette smoking was a more important risk factor for stroke and cerebral infarction than excessive drinking of alcohol.

Aged↗
PubMed1994

Role of transesophageal echocardiography in the diagnostic assessment of cardiac sources of embolism in patients with acute ischemic stroke.

To evaluate the role of transesophageal echocardiography (TEE) in the diagnostic assessment of cardiac sources of embolism in acute ischemic stroke, 94 consecutive patients (44 men and 50 women, aged 22-82 years) with acute ischemic stroke were prospectively studied. Of these, 34 patients had clinical evidence of heart disease. Both transthoracic and transesophageal echocardiograms were recorded on the same day for each patient. Transthoracic echocardiography (TTE) identified a possible cardiac source of embolism in 2 patients (6%) with and in 3 (5%) without clinical heart disease. TEE identified a possible cardiac source of embolism in 21 patients (62%) with and in 18 (30%) without clinical heart disease. TEE was superior to TTE for the detection of a cardiac source of embolism in patients with acute ischemic stroke (41 vs. 5%, p < 0.001). Factors significantly associated with a greater likelihood of such cardiac sources of embolism included left atrial enlargement, atrial fibrillation and a younger age. The yield of TEE in identifying a possible cardiac source of embolism was higher in patients with clinical evidence of heart disease than in those without.

Acute Disease↗
PubMed1993

Effects of hyperlipidemia on the vascular reactivity in the Wistar-Kyoto and spontaneously hypertensive rats.

We studied the effects of hyperlipidemia on the vascular responsiveness in aortas isolated from control rats and rats receiving a high cholesterol-high fat (HC-HF) diet (1% cholesterol and 20% olive oil). The total plasma cholesterol, very low density lipoprotein (VLDL)-, low density lipoprotein (LDL)-cholesterol, VLDL-, LDL-, high density lipoprotein (HDL)-triglyceride levels were markedly elevated in HC-HF chow fed Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) compared to the respective normal chow fed control rats. The increase in plasma cholesterol and triglyceride levels were time-dependent. Higher levels of cholesterol and triglyceride were observed in SHR compared to WKY. In the aortic arches and abdominal aortas obtained from the SHR and WKY fed the HC-HF chow for 8 week, evoked intimal lesions were more pronounced than those noted after 4 weeks of HC-HF chow fed. The aortic arches of SHR and WKY were significantly more affected by the intimal lesion (surface area damage and fatty streak formation) than the abdominal aortas of the respective rat strain. The damage of surface area and thickness of fatty streaks were significantly augmented with the period the rats were fed the HC-HF diet. In the denuded aortic arches of the WKY and of rats receiving HC-HF diet for 8 weeks, significantly attenuated ED50 values and augmented maximal responses for phenylephrine (0.01-30 microM)-induced contraction were obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1992

Mutagenesis analysis of the self-cleavage domain of hepatitis delta virus antigenomic RNA.

To determine the sequence requirements and structural features of the self-cleavage domain of hepatitis delta virus (HDV) antigenomic RNA, we constructed a series of mutants and measured the rate constant of the cleavage reaction for each. The self-cleavage activity of HDV RNA of antigenomic sense was found to reside in a region of less than 90 nucleotides in length. The catalytic domain contained a long complementary sequence which could be deleted to half of its original size. Moreover, this region could be replaced by other sequences as long as they could fold into a stem-and-loop structure. The catalytic domain also required a 6-basepair helix adjacent to the cleaving point for activity. The structural features of these two base-pairing regions are quite similar to those of the HDV genomic self-cleavage domain. The cleavage site as well as the the hinge region (the sequence between the two stems) requires specific sequences for activity.

Base Sequence↗
PubMed1992

Two polyhydroxylated steroids from the Chinese soft coral Sinularia microclavata.

Two polyhydroxylated steroids have been isolated from the South China Sea soft coral Sinularia microclavata, and their structures were established as 24-methylenecholestane-1 alpha,3 beta,5 alpha,6 beta-tetrol and 1 alpha,3 beta,5 alpha-trihydroxy-24-methylenecholestan-6-one from spectral evidence and from comparison with two reference compounds, numersterol A and 24-methylenecholestane-1 alpha,3 beta,5 alpha,6 beta, 25-pentol, which were isolated from the soft corals, Simularia numerosa and Sarcophyton glaucum, respectively.

Animals↗
PubMed1992

Forced oscillations in sympathetic nerve discharge.

Periodic electrical stimulation of the medullary raphe or lateral tegmental field in baroreceptor-denervated cats was used to force the central systems responsible for the 10-Hz and 2- to 6-Hz rhythms in post-ganglionic sympathetic nerve discharge (SND). The 10-Hz rhythm in SND could be entrained either to the frequency of medullary stimulation or to harmonics of the stimulus frequency. The harmonic of the stimulus frequency to which the 10-Hz rhythm was entrained in one postganglionic nerve could be different from that in another nerve. On this basis, we propose that the circuits responsible for the 10-Hz rhythms in SND may be modeled as a system of coupled nonlinear oscillators, each of which either influences one postganglionic nerve or nonuniformly affects different postganglionic nerves. The relatively wide band 2- to 6-Hz component in SND could be forced into a stable oscillatory state by medullary stimulation at frequencies between 3 and 5 Hz. This observation is consistent with the view that the 2- to 6-Hz component reflects the complex behavior of a nonlinear oscillator rather than the output of a physiological noise generator.

Animals↗
PubMed1992

Dissociation of inhibitory effects of low-dose ASA on thromboxane production and platelet aggregation in ischemic stroke patients.

Acetylsalicylic acid (ASA) inhibits thromboxane production and hence platelet aggregation. However, individual variations in platelet aggregability and serum thromboxane B2 (TxB2) concentration after a low dose of ASA (40 mg/day) have been reported. To clarify this issue, we studied plasma thromboxane levels and platelet aggregation in 43 ischemic stroke patients. Of the 22 patients who received 100 mg of ASA daily, dissociation between inhibitory effects of ASA on the plasma TxB2 level and threshold concentrations of adenosine diphosphate was found in three cases after one month of drug administration, and in three cases after six, 12 and 18 months of ASA therapy. This dissociation also developed in two patients after one month and six months, respectively, of treatment in the 21 patients who received 300 mg of ASA daily. The dissociation between the inhibitory effects on plasma TxB2 and the circulating platelet aggregate ratio was found in two cases after taking medication for one month, and in four cases after six, 12, 18 and 24 months of therapy in the 100 mg ASA group. In the 300 mg ASA group, dissociation was noted in two cases after one month of medication, and in two cases after six and 12 months of medication. In these patients, although their TxB2 levels were inhibited to almost unmeasurable levels, platelet aggregation was still not inhibited. This ASA inhibitory dissociation phenomenon on platelet function may be due to the low dose of ASA, individual differences in platelet function in response to ASA therapy, or factors other than those involved in the cyclooxygenase system.

Aged↗
PubMed1991

Electroacupuncture in rats: evidence for naloxone and naltrexone potentiation of analgesia.

Low frequency electroacupuncture (EA) analgesia has been thought to be mediated by endogenous opioids. Among other lines of evidence, it has been reported that EA stimulation delivered at 2 and 2-15 Hz in rats could be blocked or partially antagonized by naloxone (NAL) and naltrexone (NTX). In contrast, experiments in one of our laboratories (D.J.M.) showed that NAL did not inhibit 2 Hz, and even potentiated 125 Hz EA analgesia. In an attempt to resolve these discrepancies, we conducted joint experiments in the U.S.A. and in China using the methods which previously yielded NAL reversibility of EA analgesia. In no experiment did opiate antagonists block or reduce EA analgesia. On the contrary, we found that, in most experiments, NAL and NTX potentiated 2 and 2-15 Hz EA analgesia respectively. The potentiation occurred independently of laboratory methods, geographic location of the experiment, strain (Chinese or American), tail temperature, sex, and weight of rats. This potentiation suggests the existence of an opioid anti-analgesic system or that NAL and NTX acquired analgesic properties following EA. These results indicate that EA analgesia in rats is a variable phenomenon even when laboratory methods are rigorously replicated. The EA stimulation may activate multiple conflicting neural circuits which interact and ultimately modulate the analgesic outcome.

Aging↗
PubMed1991

The strength and periodicity of D. melanogaster circadian rhythms are differentially affected by alterations in period gene expression.

The per gene of D. melanogaster influences or participates in the generation of biological rhythms. Previous experiments have identified the head as the location from which per exerts its effect on circadian rhythms. To localize further this region and to examine the effects of altered levels and altered spatial expression patterns of the per gene on circadian rhythms of locomotor activity, we have characterized transformed lines containing per gene constructs missing substantial cis-acting regulatory information. The data suggest that wild-type levels of per gene expression are necessary in only a small fraction of the nervous system for near wild-type periods, whereas a larger fraction of per-expressing cells in the brain contributes to the strength of the circadian rhythms.

Animals↗
PubMed1991

Comparison of in vitro platelet aggregation and its inhibition by three antithrombotic drugs between human and guinea pig.

Platelets of guinea pigs are frequently used to evaluate the effect of new antiplatelet agents. Although several studies have compared the platelet aggregation between humans and guinea pigs, but so far the information is still limited. In this study, we compare the inhibitory effect of aspirin, dipyridamole and pentoxifylline on the platelet aggregation induced by adenosine diphosphate (ADP), collagen, arachidonic acid and thrombin between humans and guinea pigs. The results for humans and guinea pigs were compared and analysed by two-way analysis of variance (ANOVA). Our results showed: 1. The trends wherein these three drugs suppressed collagen-induced platelet aggregation was very similar in humans and guinea pigs. 2. In ADP-induced aggregation, the trend of inhibition caused by the three drugs was also similar in humans and guinea pigs except that a difference in platelet disaggregation at a late phase of platelet aggregation was noted. 3. In arachidonic acid- and thrombin-induced aggregations, the trend of inhibition caused by the three drugs was somewhat different in humans and guinea pigs. 4. Considering all activators as a whole, it was found that the status of platelet disaggregation at the late phase of platelet aggregation was different in humans and guinea pigs. Therefore, we concluded that: 1. Collagen was the most appropriate platelet activator when we used platelets of guinea pigs to study the effect of new antiplatelet agents. 2. When platelets of guinea pigs were used to study platelet aggregation, no matter which activator was used, we should avoid using the late phase of aggregation as the control index for comparison, because the results thus obtained might not be applicable to human platelets.

Adenosine Diphosphate↗
PubMed1991

A 5-year surveillance of sensitivity in vivo of Plasmodium falciparum to pyronaridine/sulfadoxine/pyrimethamine in Diaoluo area, Hainan Province.

The surveillance of sensitivity of P. falciparum to pyronaridine/sulfadoxine/pyrimethamine has been carried out in Diaoluo area in Hainan Province where chloroquine-resistant falciparum malaria is endemic, covering an area of 406 square kilometers, with a population of 3745 in 1986. From 1986 all outpatients diagnosed as falciparum malaria were administered with PND/S/P as the only antimalarial. In vivo sensitivity of P. falciparum was measured in some patients who were treated in hospital. It was demonstrated that P. falciparum in the Diaoluo area has retained its sensitivity to a single oral dose of PND/S/P of 500/1,000/50 mg with 100% cure rate for at least 5 years.

Adolescent↗
PubMed1990

A simple method to create carotid endothelial laceration and acute platelet thrombus in vivo in guinea-pig.

A simple method, named 'clamp method', was developed to create carotid endothelial laceration and produce acute platelet thrombus in vivo in guinea-pig. This method used a hemostatic forceps to clamp common carotid artery of anesthetized guinea-pig at a tangent angle. Our study included two parts. The Part one demonstrated the procedures and effects of the 'clamp method': sixteen guinea-pigs were divided equally into control and heparin-treated groups. These two groups received the same clamping procedures except that the heparin-treated group was administrated with heparin (5,000U/kg) intravenously before clamping. One hour after the clamping, carotid arteries were resected and observed under scanning electron microscopy. The results showed that large carotid mural thrombi were formed in the control group with a mean surface area of 1.75 +/- 0.63 mm2 (M +/- SD, n = 8). In the heparin-treated group, the thrombus formation was prevented and linear endothelial lacerations were seen clearly. The Part two of our study identified the histologic nature of the thrombus produced by the 'clamp method': eight guinea-pigs received same procedures as that of control group in the Part one except that the carotid arteries were resected 5 min after performing the clamping. Four of the eight specimens were prepared for observation under transmission electron microscopy. The results showed that platelets adhered onto the subendothelial substances and formed platelet thrombi in the endothelial lacerations within 5 min after the carotid clamping.

Animals↗
PubMed1990

Cloning of an integrin beta subunit exhibiting high homology with integrin beta 3 subunit.

cDNAs for another beta subunit of the integrin family were isolated with the aid of polymerase chain reaction and sequenced. The combined cDNA sequence is 3110 base pairs (bp) in size and has one long open reading frame of 2388 bp. The deduced amino acid sequence is similar to those of other integrin beta subunits but does not correspond to beta 1, beta 2, beta 3, or beta 4 subunits. This beta subunit is divided by a membrane-spanning domain into a large extracellular domain at the N-terminal side and a small intracellular domain at the C-terminal side. The extracellular domain has a cysteine-rich region that contains four repeats of 8-cysteine motifs. All 56 cysteine residues found in the extracellular domains of other mature beta subunits are present in this beta subunit. The beta subunit reported here has particularly high homology with the beta 3 subunit. The mRNA for the molecule is approximately 3.5 kbp in size and is expressed in various cell types. Other researchers have recently reported additional beta subunits that associate with the vitronectin receptor alpha subunit. The deduced amino acid sequence of this molecule contains the N-terminal partial amino acid sequence of one of these beta subunits, beta x. The beta subunit described herein seems to be identical to the beta x subunit and to function as the beta subunit of a vitronectin receptor.

Amino Acid Sequence↗
PubMed1990

[Interaction of abdominal vagus and greater splanchnic nerve activities in the nucleus tractus solitarius of the rabbit].

Experiments were performed on 67 rabbits. Effects of stimulation of the central ends of abdominal vagus and greater splanchnic nerve on arterial blood pressure before and after destruction of nucleus tractus solitarius (NTS) and the unit discharges in the NTS before destruction were observed. As a result, we suggest that both the afferents coming from the abdominal vagus and greater splanchnic nerve not only converge on NTS neurons but also interact with each other. Subthreshold stimulation elicited from one of the afferent fibers suppresses the arterial blood pressure responses caused by the other afferent. Similarly, background stimulation elicited from one afferent can suppress the NTS unit discharges caused by the other afferent. It is much easier for abdominal vagal afferent to inhibit the NTS unit discharges and the arterial blood pressure changes elicited by stimulation of the splanchnic nerve. A possible mechanism of such relationship was discussed.

Animals↗
PubMed1989

[Therapeutic effect of pyronaridine in plain tablets and enteric-coated tablets in falciparum malaria patients].

A new oral dosage regimen and formulation of pyronaridine basing on the pharmacokinetic studies and a theoretical dosage regimen reported previously, was clinically evaluated for its therapeutic and undesirable effects on falciparum malaria patients in west Hainan Province, where chloroquine-resistant falciparum malaria was prevalent. 32 cases were treated with pyronaridine by the new dosage regimen of 0.5 g in d1, and 0.3g in d2 in plain tablets (group A), while additional 32 patients received enteric-coated tablets of pyronaridine by the current dosage regimen as a control (group B), which was 0.4 g x 2 on d1, and 0.4g on d2. The average fever clearance time for A and B groups was 27.0 +/- 14.1 and 30.2 +/- 13.8h respectively (P greater than 0.05), and the clearance time for asexual parasites was 57.2 +/- 10.2 and 57.9 +/- 8.7h. Upon 28d following-up examination the cure rates were found to be 100% in group A and 93.8% in group B. The undesirable responses were recorded in 18.8% of group A patients (6/32), and 28.1% of group B (9/32) respectively, and they were light and tolerable and short in time duration. It was shown that the new dosage regimen of pyronaridine could retain the same therapeutic effect as that currently used, although the total dose was reduced by one third. Hence, an important basis was provided for more rational use and further study of pyronaridine in malaria therapy.

Adolescent↗
PubMed1989

[In vivo sensitivity of Plasmodium falciparum to piperaquine phosphate assayed in Linshui and Baisha counties, Hainan Province].

Fifty-three cases of falciparum malaria in Linshui County, Baisha County and Sanya Municipality were treated with piperaquine phosphate at a total dose of 1.5g base over 3 days in July to December, 1986. The mean defervescence time was 36 +/- 20.7h; the mean asexual parasite clearance time was 69.7 +/- 20.9h. At 14-28d follow-up recrudescence was observed with asexual parasitemia in 7 of the 47 cases, showing RI resistance to piperaquine. Gametocytemia was positive in 35 cases (74.5%) during the follow-up period.

Adolescent↗
PubMed1989

Antimalarial and toxic effect of triple combination of pyronaridine, sulfadoxine and pyrimethamine.

The triple combination of pyronaridine, sulfadoxine and pyrimethamine which has been proven to be efficient in delaying emergence of drug resistance of rodent malarial parasites was further studied for potential application to malaria control. The antimalarial effect of the triple combination on Plasmodium berghei ANKA-infected mice and the toxic effects in mice and rats were additive. A single dose of pyronaridine 500 mg in combination with sulfadoxine, 1000 or 1500 mg, and pyrimethamine, 50 or 75 mg, given to 72 acute falciparum malaria patients resulted in a 100% cure rate with nil or mild side effects, and no recrudescence of asexual parasite over 4-week follow-up. Preliminary experiments on the drug effect on sporogony showed that the drug combination at the dose used could not completely interrupt the sporozoite formation although many retarded oocysts were found.

Animals↗