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Biomedical subjects

J F Zhang

Publications and source records attributed to J F Zhang.

At least 55 records · Page 3Linked to original sources
PubMed1993

The effect of prices on alcohol consumption in New Zealand 1983-1991.

The strength of the effect of prices on alcohol consumption is of relevance in determining the potential impact that alcohol taxes have on consumption and, thereby, alcohol-related problems. This price-consumption relationship was investigated for New Zealand. Multiple regression analysis was employed using quarterly aggregate consumption and price data for 1983-1991. Price elasticities of alcohol consumption were estimated to be -1.1, -1.1, 0, -2.0 for beer, wine and spirits beverage, and absolute (total) alcohol consumption, respectively. These elasticity estimates and the degree to which prices explained consumption trends in the regression equations, suggest that price had a strong effect on alcohol consumption in New Zealand during the period investigated. Thus, the current taxing policy, in which excise tax is indexed to inflation, is deemed a useful tool for preventing an increase in alcohol consumption and alcohol-related problems.

Journal Article↗
PubMed1993

The importance of amount and location of drinking for the experience of alcohol-related problems.

People's self report of a variety of alcohol-related problems was collected as part of a national survey carried out in New Zealand in 1988. These problems included self perception of adverse effects of drinking on a number of life areas such as health, friendships and financial position; items covering tangible consequences of alcohol use and items suggestive of alcohol dependence. The experience of these problems was predicted from a number of socio-demographic variables and respondent's reports of their typical drinking behaviour. Of the socio-demographic variables only age was found to relate strongly to experience of problems. The overall frequency of drinking relatively large amounts and the typical quantity drunk in certain licensed premises (hotels, taverns and clubs) and the typical quantity drunk in others' homes predicted the experience of problems. These findings are similar to research from other countries using different methodologies and support the likely effectiveness of prevention strategies which reduce the access of young people to alcohol and which aim to influence the amounts consumed in drinking sessions on licensed premises.

Adolescent↗
PubMed1993

[Effect of ligustrazine on isolated myocardial ischemic reperfusion injury in rats].

In recent years, it is believed by some scholars that the injury of myocardial ischemic reperfusion is correlated to the thromboxane A2 (TXA2) released by platelets. In order to explore that whether the myocardial and hemangio-endothelial cells participate in the TXA2 production during the process of reperfusion, the modified Langendorff method was used to establish the model of reperfusing the isolated rat heart. On the other hand, this experiment was also intended to observe the effect of ligustrazine on the injury of myocardial ischemic reperfusion. The results revealed that the level of thromboxane B2 (metabolite of TXA2) and lactic dehydrogenase (LDH) in coronary sinus reflux fluid increased during the process of reperfusion, while the level of 6-keto-PGF1 alpha in the same fluid relatively decreased (P < 0.05). The ratio of TXB2/6-keto-PGF1 alpha was raised. The ligustrazine inhibited the release of TXB2 and LDH, but promoted the production of 6-keto-PGF1 alpha (P < 0.05). The results also proved that the myocardial and hemangio-endothelial cells could synthesize TXA2, and the amount of TXA2 released increased during the reperfusion of ischemic myocardium, which was likely to be the major factor of the injury of ischemic myocardial reperfusion. Ligustrazine plays an important role in protecting the myocardium.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Sympathetic neurons mediate developmental change in cardiac sodium channel gating through long-term neurotransmitter action.

Innervation of nerve and muscle cells during development is often accompanied by changes in the expression and function of ion channels in the postsynaptic cell. However, the signaling pathways whereby the presynaptic nerve influences the properties of the postsynaptic cell are less well understood. Indirect evidence suggests that cardiac voltage-gated Na+ channels undergo important changes during development. Here, we compare directly single voltage-gated Na+ channel currents from neonatal and adult rat ventricular myocytes and report a negative shift in the voltage dependence of channel gating during development, leading to a significant speeding of channel activation and inactivation at a fixed membrane potential. These developmental changes can be mimicked in vitro by innervation of neonatal myocytes with sympathetic neurons. The effect of sympathetic neurons is blocked by the beta-adrenergic receptor antagonist propranolol and is mimicked by prolonged coculture of neonatal myocytes with a membrane-permeable cAMP analog. Thus presynaptic neurons can control the developmental phenotype of ion channels in a postsynaptic cell through a classic receptor-mediated neurotransmitter action that involves a defined second messenger pathway.

Adrenergic Fibers↗
PubMed1992

[Effect of electrical stimulation of paraventricular nucleus on stress gastric mucosal lesion in rats].

The effect of electrical stimulation of hypothalamic paraventricular nucleus (PVN) on gastric mucosal lesion induced by RWIS (restraint + water-immersion stress) in rats was investigated. The main results were as follows: (1) Electrical stimulation of the PVN could obviously increase the stress gastric mucosal lesion. (2) Microinjection of L-glutamate into PVN could produce similar effect to that of PVN stimulation. (3) PVN lesion could significantly decrease the stress gastric mucosal lesion. (4) The above mentioned effects were attenuated by vagotomy or atropine injected subcutaneously. (5) A further study indicated that the gastric mucosal blood flow was reduced upon PVN stimulation, but no obvious changes of gastric juice volume, total acid output, pepsin activity and gastric barrier mucus were observed. The results mentioned above indicate that the PVN is one of the specific CNS areas capable of increasing the stress-induced gastric mucosal lesion mediated through the cholinergic fibers of the vagal nerve and related to decreased gastric mucosal blood flow, while gastric acid output, pepsin activity and gastric barrier mucus do not seem to play any important role.

Animals↗
PubMed1991

The effect of calcitonin gene-related peptide on arrhythmia caused by adenosine diphosphate and desacetyldigilanide-C in rats.

We investigated the effect of calcitonin gene-related peptide on the arrhythmia induced by two drugs in rats. The results of our experiments have proved that calcitonin gene-related peptide could reduce the degree of atrioventricular block, protect against the attacks of sinus standstill and ventricular fibrillation produced by adenosine diphosphate, and improve restoration of sinus rhythm. Calcitonin gene-related peptide was able to eliminate sinus standstill and ventricular fibrillation resulting from administration of desacetyldigilanide-C. These results demonstrate that calcitonin gene-related peptide has strong antiarrhythmic effects in experimental animals.

Adenosine Diphosphate↗
PubMed1991

Effects of external protons on single cardiac sodium channels from guinea pig ventricular myocytes.

The effects of external protons on single sodium channel currents recorded from cell-attached patches on guinea pig ventricular myocytes were investigated. Extracellular protons reduce single channel current amplitude in a dose-dependent manner, consistent with a simple rapid channel block model where protons bind to a site within the channel with an apparent pKH of 5.10. The reduction in single channel current amplitude by protons is voltage independent between -70 and -20 mV. Increasing external proton concentration also shifts channel gating parameters to more positive voltages, consistent with previous macroscopic results. Similar voltage shifts are seen in the steady-state inactivation (h infinity) curve, the time constant for macroscopic current inactivation (tau h), and the first latency function describing channel activation. As pHo decreases from 7.4 to 5.5 the midpoint of the h infinity curve shifts from -107.6 +/- 2.6 mV (mean +/- SD, n = 16) to -94.3 +/- 1.9 mV (n = 3, P less than 0.001). These effects on channel gating are consistent with a reduction in negative surface potential due to titration of negative external surface charge. The Gouy-Chapman-Stern surface charge model incorporating specific proton binding provides an excellent fit to the dose-response curve for the shift in the midpoint of the h infinity curve with protons, yielding an estimate for total negative surface charge density of -1e/490 A2 and a pKH for proton binding of 5.16. By reducing external surface Na+ concentration, titration of negative surface charge can also quantitatively account for the reduction in single Na+ channel current amplitude, although we cannot rule out a potential role for channel block. Thus, titration by protons of a single class of negatively charged sites may account for effects on both single channel current amplitude and gating.

Animals↗
PubMed1991

[Relation between chronic hepatitis and cirrhosis in the type of differentiation of symptoms and signs and endocrine hormone].

In order to investigate the objective index of the type of differentiation of symptoms and signs between chronic hepatitis and cirrhosis, the levels of serum Tes, ALD, HCT, INS, GR, gastrin, T3, T4, TSH were tested in the chronic hepatitis and cirrhosis of 27 cases of sthenia-syndrome and 61 cases of asthenia-syndrome. Meanwhile, 30 cases of healthy people were taken as the control. The results indicated that the levels of serum Tes, T3, T4, gastrin in the group of asthenia-syndrome (P less than 0.01, P less than 0.05). The levels of serum T4 and gastrin were increased in the group of sthenia-syndrome than in the groups of asthenia-syndrome and control (P less than 0.01). The levels of serum ALT, HCT, INS, and GR were significantly different between the group of asthenia-syndrome and that of sthenia-syndrome. This suggests that clinic symptoms were concerned with the level of serum endocrine on chronic hepatitis and cirrhosis, such as the function of genital, thyroid, adrenal gland and pancrease. The observation of the levels of serum Tes, T3, T4, ALT, INS, GR and gastrin may be an objective index to differentiate the chronic hepatitis and cirrhosis.

Adult↗
PubMed1990

[Effect of scopolia drugs on the gastric mucosal lesion in rats].

In the present paper, effects of scopolia drugs (scopolamine, anisodine, anisodamine) on experimental gastric mucosal lesion models in rats were investigated. Scopolia drugs were found to be effective anti-ulcer agents in three experimental gastric ulcer models (i.e. cold-restraint stress induced ulcer, indomethacin induced ulcer and acetic acid induced chronic ulcer) in rats in a dose dependent manner. Biochemical analysis of gastric juice and blood showed that scopolia drugs could inhibit gastric acid secretion and pepsin activity, increase gastric barrier mucus and concentration of serum gastrin, suggesting that these actions may contribute to its anti-ulcer effect.

Animals↗
PubMed1989

[Diagnosis of contaminated small bowel syndrome following subtotal gastrectomy: a comparative study of mannitol-BHT and jejunal bacteriology].

Recent reports from abroad showed that lactulose breath hydrogen test (BHT) is a noninvasive and an accurate method for diagnosing contaminated small bowel syndrome (CSBS). In this study, BHT was carried out with mannitol, an inexpensive and rich-in-source sugar, instead of lactulose. In comparison with the "gold standard" of jejunal bacteriology, it was disclosed that a double peak pattern of breath hydrogen response after oral administration of mannitol was characteristic of CSBS with a sensitivity of 71.4% and a specificity of 66.7%, which are about same as those of the lactulose-BHT used abroad.

Adult↗
PubMed1989

Alpha-1 adrenergic stimulation of 1,4,5-inositol trisphosphate formation in ventricular myocytes.

We demonstrated previously that alpha-1 adrenergic catecholamines modulate cardiac automaticity in a manner that is dependent upon the function of a pertussis toxin sensitive guanine nucleotide binding protein (G protein). Furthermore, we demonstrated that alpha-1 adrenergic receptor stimulation promotes the accumulation of inositol monophosphate (IP1). In the present study we used high-pressure liquid chromatography to resolve individual inositol phosphate isomers formed in norepinephrine-stimulated cultured rat ventricular myocytes. Norepinephrine stimulated a rapid, transient increase in 1,4,5-inositol trisphosphate (1,4,5-IP3) which was followed by slower, sustained increases in 1,3,4-IP3, inositol bisphosphate (IP2) and IP1. IP1 was composed of two major isomers with retention times characteristic of 1-IP1 and 4-IP1. 4-IP1 was the predominant IP1 isomer formed during stimulation with norepinephrine suggesting that the polyphosphoinositides rather than phosphatidylinositol are the principal targets of norepinephrine-stimulated phospholipase C activity in the heart. This was confirmed in studies performed on myocyte membranes which demonstrated proportionately greater IP2 and IP3 (relative to IP1) accumulation in response to norepinephrine. G protein regulation of alpha-1 adrenergic-dependent inositol phospholipid hydrolysis also was examined. In myocyte membranes, guanosine-5'-0-(3-thiotriphosphate) induced the accumulation of IP2 and IP3 and was required for the stimulatory effect of norepinephrine. This response was not impaired after pretreatment with pertussis toxin. These results indicate that the myocyte alpha-1 adrenergic receptor is coupled to a polyphosphoinositide-specific phospholipase C by a pertussis toxin insensitive G protein and suggest that under certain conditions IP3 may serve an important role in alpha-1 adrenergic modulation of cardiac function.

Animals↗
PubMed1989

[Influence of microinjection of bicuculline into ventrolateral medulla on the suppression of cardiac function induced by diazepam in rabbits].

Experiments were carried out on 48 rabbits anaesthetized with urethane (1 g/kg). The animals were immobilized with gallamine triethiodide and ventilated artificially. Both intravenous injection of diazepam (0.5 mg/kg) and intracerebroventricular injection of flurazepam (2 mg in 50 microliters) or gamma-aminobutyric acid (GABA) (300 micrograms in 50 microliters) decreased the peak value of left ventricular pressure area of cardiac force loop and dp/dtmax. These suppressive effects of diazepam and flurazepam were prevented by intracerebroventricular injection of picrotoxin (15 micrograms in 50 microliters) or microinjection of bicuculline (3 micrograms in 0.5 microliter) into bilateral rostral ventrolateral medulla (gamma VLM). The results suggest that the inhibitory effects of diazepam on cardiac function may be mediated by activation of GABA receptor in gamma VLM.

Animals↗
PubMed1989

[Intracerebroventricular administration of hypertonic saline inhibits the reabsorption of water and sodium in the proximal tubule].

In anaesthetized rats with unilateral section of the renal nerve, the effect of intracerebroventricular (icv.) administration of hypertonic saline on the reabsorption of water and sodium in the proximal tubule was investigated, using the lithium clearance method. After icv. administration of hypertonic saline, the lithium clearance (CLi to glomerular filtration rate (GFR) ratio increased from 0.37 +/- 0.04 to 0.51 +/- 0.05 (P less than 0.01) in the denervated kidneys and from 0.26 +/- 0.03 to 0.31 +/- 0.04 (P less than 0.05) in the innervated kidneys, respectively. GFR, urine flow rate (V), urinary sodium excretion (UNaV) and urinary potassium excretion (UkV) increased in both innervated and denervated kidneys, the increments of V, UNaV and UkV being greater in the denervated kidneys than in the innervated kidneys. In micropuncture experiments, icv. administration of hypertonic saline caused an increase in proximal tubule flow rate, from 24.42 +/- 1.84 nl/min to 31.86 +/- 3.09 nl/min, without significant change in proximal tubule fluid osmolality in the innervated kidneys. These data support the notion that the diuresis and natriuresis induced by icv. administration of hypertonic saline in the anaesthetized rat result from an increase in GFR and a decrease in the reabsorption of water and sodium in the proximal tubule. Humoral factors are probably involved in these responses.

Absorption↗