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Biomedical subjects

Z Xue

Publications and source records attributed to Z Xue.

At least 55 records · Page 3Linked to original sources
PubMed1996

[The clinical significance of changes in lung function, oxygen consumption and some bio-active substances in immigrants into high altitude].

Lung function was assayed in 40 healthy adults who moved to high altitude area (Lhasa, 3,658 m above sea level, Group A) recently and 160 who had lived for a long period of time (Group B). Oxygen consumption was also measured and serum triiodothyronine (T3), thyroxin (T4), reverse triiodothyronine (rT3), endogenous digitalis factors (EDF), plasma renin activity (PRA), angiotensin II (AII), aldosterone (ALD) and the concentration of atrial natriuretic peptide (ANP) were determined with radioimmunoassay in 80 of them. The results showed: (1) In both groups, lung volume was increased, flow rate of ventilation markedly quickened and diffusion enhanced as compared with the normal value; (2) Thyroid function was reduced; (3) ANP and EDF were markedly increased and ALD was reduced. AII was markedly increased and PRA was normal in Group A but on the contrary in Group B. The possible relation of these changes with the length of time of stay at high altitude is discussed.

Adaptation, Physiological↗
PubMed1995

5-HT3 agonist-induced dopamine overflow during withdrawal from continuous or intermittent cocaine administration.

This experiment examined alterations in the ability of the highly selective 5-HT3 receptor agonist, 1-(m-chlorophenyl)-biguanide (mCPBG), to induce dopamine (DA) overflow in caudate brain slices obtained from rats withdrawn from continuous or intermittent cocaine administration. Rats were pretreated with 40 mg/kg per day cocaine for 14 days by either subcutaneous injections or osmotic minipumps, and then withdrawn from this regimen for 7 days. Caudate brain slices were obtained, and perfused with artificial cerebrospinal fluid. Following an equilibration period, the slices were then perfused with 25, 50, or 100 microM mCPBG. The samples were assayed for DA content by HPLC with electrochemical detection. The results indicated that the pretreatment with intermittent cocaine did not consistently alter the ability of mCPBG to induce DA overflow, although there was a reduction in the amount of DA released by the highest concentration of mCPBG. In contrast, pretreatment with continuous cocaine administration consistently and significantly attenuated the ability of mCPBG to induce DA overflow. The DA overflow induced by mCPBG was partially dependent on extracellular Ca2+ in the perfusion medium for the saline control and intermittent administration subjects: elimination of Ca2+ from the medium significantly reduced, but did not eliminate, DA overflow for these two groups. In contrast, elimination of Ca2+ from the perfusion medium had a significant enhancing effect on mCPBG-induced DA overflow in the continuous administration rats. These results suggest that distinct temporal patterns of cocaine administration differentially alter the ability of a 5-HT3 agonist to increase extracellular DA levels, and that this effect may be related to an impairment of Ca(2+)-dependent release.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

The nucleolus: an organelle formed by the act of building a ribosome.

Recent evidence corroborates the idea that the structure of the nucleolus need not be strictly maintained for proper function, suggesting that the organelle is composed of supramolecular assemblies formed during rRNA synthesis. More controversial is whether the nucleolus exists in the absence of rRNA synthesis and whether it interacts with the nuclear scaffold. The simultaneous and highly integrative nature of building a ribosome is reflected in the numerous observations showing that proteins involved in all aspects of ribosomal biogenesis affect pre-rRNA processing. The identification of several new nucleolar proteins without an obvious role in pre-rRNA metabolism may provide the field with long sought after assembly factors that might be key players in eukaryotic ribosome biogenesis.

Animals↗
PubMed1995

[A new and simple method of evaluating left ventricular contractility and its application].

After making theoretical analysis, we detected the relationship among the maximal tension of ventricular contraction, left ventricular end-systolic pressure and stroke volume, and then derived a new and simple method of evaluating left ventricular contractility, the slope of the left ventricular end-systolic pressure-volume relation (Emax). Twelve mongrel male dogs were used to test this method. The results show that the value of Emax (0.60 +/- 0.16 kPa/ml) coming from this simple method is very close to that from complicated method; this method has good repetitiveness and is very sensitive to the variation of myocardial contraction. Using the method for evaluating left ventricular contraction after ischemia, we found the Emax more cogent than other hemodynamic parameters. Therefore, this method is an efficient method of evaluating left ventricular contraction.

Animals↗
PubMed1995

[The significance of changes in plasma renin angiotensin aldosterone system and atrial natriuretic factor in patients with high altitude myocardial hypoxidosis].

Plasma renin activity (PRA), angiotensin II (ATII), aldosterone (ALD) and atrial natriuretic factor (ANF) were determined in 30 patients with high altitude myocardial hypoxidosis (HAMH) with radioimmunoassay and the data were compared with those of 40 healthy subjects and 26 patients with high altitude chronic cardiopathy (HACC). All of them have been in Lasa, a place with an altitude of 3,658 meter, for a long time. The results showed that PRA and plasma ATII increased significantly (P < 0.05-0.01) and plasma ANF decreased significantly (P < 0.01) in patients with HACC and were higher than those in the control. It is suggested that disturbance of these biologically active substances might play a role in the development of HAMH.

Adolescent↗
PubMed1994

Nucleolar proteins that bind NLSs: a role in nuclear import or ribosome biogenesis?

In a search for proteins that bind nuclear localization sequences (NLSs), a number of nucleolar proteins with diverse functions were found. It is thought that the assay fortuitously uncovered a novel domain that mediates the interaction between these nucleolar proteins and ribosomal proteins containing NLS-like sequences. The domain is highly acidic and contains a number of serines forming putative casein kinase II sites. Here, we propose a model in which the nucleolar proteins catalyse the assembly of ribosomal proteins with pre-rRNA.

Journal Article↗
PubMed1994

Yeast NPI46 encodes a novel prolyl cis-trans isomerase that is located in the nucleolus.

We have identified a gene (NPI46) encoding a new prolyl cis-trans isomerase within the nucleolus of the yeast Saccharomyces cerevisiae. The protein encoded by NPI46 was originally found by us in a search for proteins that recognize nuclear localization sequences (NLSs) in vitro. Thus, NPI46 binds to affinity columns that contain a wild-type histone H2B NLS but not a mutant H2B NLS that is incompetent for nuclear localization in vivo. NPI46 has two domains, a highly charged NH2 terminus similar to two other mammalian nucleolar proteins, nucleolin and Nopp140, and a COOH terminus with 45% homology to a family of mammalian and yeast proline isomerases. NPI46 is capable of catalyzing the prolyl cis-trans isomerization of two small synthetic peptides, succinyl-Ala-Leu-Pro-Phe-p-nitroanilide and succinyl-Ala-Ala-Pro-Phe-p-nitroanilide, as measured by a chymotrypsin-coupled spectrophotometric assay. By indirect immunofluorescence we have shown that NPI46 is a nucleolar protein. NPI46 is not essential for cell viability.

Amino Acid Isomerases↗
PubMed1994

[The effects of superoxide dismutase on acute myocardial ischemia and lipid peroxidation in rabbits].

There are controversies about the action of superoxide dismutase (SOD) on acute myocardial ischemia, but report about the serial changes of serum malondialdehyde (MDA) levels after myocardial infarction and the relationship between serum levels of MDA and size of myocardial infarct has not yet been found in literature. We made a study, using the acute myocardial infarct model of New Zealand rabbits. The results indicated that SOD significantly reduced the total number of pathologic Q-wave, the myocardial infarct size and serum MDA levels. A significant correlation was found between 48-hour serum MDA levels and 48-hour infarct size. Therefore, it is suggested that free radicals might play an important role in pure acute myocardial ischemic injury; SOD, administered early, could inhibit lipid peroxidation and thus protect the myocardium, and serum MDA levels might be regarded as a specific criterion for the diagnosis of myocardial infarction.

Animals↗
PubMed1994

Withdrawal from continuous or intermittent cocaine administration: changes in D2 receptor function.

Intermittent cocaine administration produces sensitization, whereas the continuous administration of cocaine produces tolerance to the effects of subsequent cocaine administration during withdrawal. The present study examined whether the effects of these two dosing regimens are related to alterations in the functional status of dopamine (DA) D2 receptors. In all experiments, rats were withdrawn for 7 days from a 14-day pretreatment regimen involving either continuous or intermittent cocaine administration. Experiments examined changes in the behavioral response to an autoreceptor-selective dose of apomorphine, the effects of sulpiride on electrically stimulated DA release in striatal brain slices and striatal D2 receptor binding, and mRNA levels. The results indicate that the continuous administration of cocaine produces findings consistent with D2 autoreceptor supersensitivity; there was enhanced inhibition of behavior after the autoreceptor-selective dose of apomorphine, decreased electrically stimulated DA release in the absence of sulpiride, and enhanced electrically stimulated DA release in the presence of sulpiride. However, there were no changes in postsynaptic D2 receptor binding or mRNA levels. Intermittent cocaine administration did not produce evidence of D2 autoreceptor subsensitivity: there was no decrease in inhibition of behavior after the autoreceptor-selective dose of apomorphine, no changes in electrically stimulated DA release in the absence or presence of D2 receptor blockade, and no change in the levels of D2 receptor binding; however, D2 mRNA levels were decreased by 22%. Overall, the present results are consistent with the hypothesis that the expression of tolerance induced by continuous cocaine administration is associated with D2 autoreceptor supersensitivity.

Animals↗
PubMed1993

Doppler flowmeter-assessed circadian rhythms in neonatal cardiac function, family history, and intrauterine growth retardation.

This study examines the circadian variation of aortic blood flow velocity, acceleration, and distance of stroke, assessed every 4 hours for 24 hours by Doppler ultrasound in 88 human newborns. Groups 1 and 2 involve neonates with a negative family history of high blood pressure or myocardial infarction monitored during the first day or between the second and tenth days postpartum, respectively; groups 3 to 6 are 2- to 10-day-old babies with a positive family history of high blood pressure (group 3) or of myocardial infarction (group 4) or with a negative family history and intrauterine growth retardation (group 5) or born prematurely (group 6). Cosinor analyses demonstrate a circadian rhythm for all variables in groups 2 and 5 (p < 0.001), with overall high values occurring around 17:40. In group 2, a circadian rhythm remains demonstrable in boys and girls considered separately, and mostly so in arbitrary subgroups of different sizes, with only slight differences in rhythm parameters among them. These results show that, with relatively small samples, reproducible circadian rhythms of cardiac function can be detected shortly after birth in neonates with a negative family history of high blood pressure or myocardial infarction.

Analysis of Variance↗
PubMed1993

[Effect of propranolol on circadian rhythm of Goldblatt hypertension in goat].

With the Goldblatt two-kidney two-clip method, persistent hypertension was reproduced in 7 goats. After hypertension was established and stabilized, a beta-receptor inhibitor Propranolol was given to the goats in the usual form of drug administration (20 mg, q 8 h) or in the form of chronotherapy (30 mg, QN). The mean value of BP was computed. The result suggested that, compared with the usual form of therapy, chronotherapy could reduce the hypertension to the same degree, but with less time and less amount of drug.

Animals↗
PubMed1993

[Structure determination of saponin XI, XII and XIII from Dipsacus asper Wall].

Three new triterpenoid glycosides (XI, XII and XIII) were isolated from the ethanol extract of the roots of Dipsacus asper Wall. Their structures were deduced as 3-O-[beta-D-glucopyranosyl(1-->4)][alpha-L-rhamnopyranosyl (1-->3)]- beta-D-glucopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->2)-alpha- arabinopyranosyl-hederagenin (XI), 28-O-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranosyl ester of XI (XII) and 3-O-[beta-D-xylopyranosyl(1-->4)-beta-D-glucopyranosyl (1-->4)][alpha-L-rhamnopyranosyl(1-->3)]-beta-D-glucopyranosyl(1-->3)- alpha-L-rhamnopyranosyl(1-->2)-alpha-arabinopyranosyl-oleanolic.ac id 28-O-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranosyl ester (XIII), respectively, based on spectral and chemical analysis.

Drugs, Chinese Herbal↗
PubMed1993

The amino terminus of mammalian nucleolin specifically recognizes SV40 T-antigen type nuclear localization sequences.

Nucleolin is a major nucleolar protein in mammalian cells that is thought to be involved in ribosome biogenesis. The discovery that nucleolin shuttles between the cytoplasm and the nucleus raises the possibility that it is also involved in transporting ribosomal or nuclear proteins to the nucleus. The three structural domains of nucleolin bear a striking resemblance to the domains of a previously identified yeast protein NSR1, although the two proteins do not share a high degree of sequence similarity. NSR1 specifically recognizes the nuclear localization sequence (NLS) of both the simian virus large T antigen (SV40 T-antigen) and the yeast histone H2B by ligand blot analysis, and is a candidate for a receptor involved in the initial stages of nuclear transport. We report here that nucleolin, either purified from Chinese hamster ovary (CHO) cells or expressed in yeast, also specifically recognizes the wild-type, but not a mutant, histone H2B nuclear localization sequence by ligand blot analysis. The NLS recognition site is located within the N-terminal domain of both proteins. In showing that nucleolin, a protein that moves between the cytoplasm and the nucleus, also has the ability to interact with nuclear localization signals, our data support the idea that shuttling nucleolar proteins play a role in nuclear transport.

Amino Acid Sequence↗
PubMed1992

[Relation between the occurrence of malignant arrhythmia during acute myocardial ischemia and the weight of ischemic myocardium in goats].

The coronary collateral circulation of goat is very spare, so myocardiac ischemia model of goat can simulate the patient previously with normal coronary circulation and suddenly developing complete occlusion of coronary arteries. In this study 80 Chengdu goats were used, and the branches of their left coronary artery were ligated. Ventricular tachycardia (VT) developed in 23 goats and ventricular fibrillation (VF) in 39 goats. VT and VF both occurred in the early phase of acute myocardial ischemia, and both had 6 min as the median time of onset. In 71 cases data on the weight of myocardiac ischemic area were collected, in which the weight percentage of ischemic area relating to the ventricles of 34 goats with VF was significantly higher than that of 37 goats without VF (35.4 +/- 2.4% vs 19.5 +/- 1.9%). After coronary ligation, 9 cases directly precipitated into VF which could not be defibrillated. In the remaining 62 cases, the weight percentage of ischemic area of 21 cases with VT was higher than that of 41 cases without VT (32.9 +/- 2.8% vs 20.9 +/- 2.1%). The relationships between the incidence of VT or VF and the weight percentage of ischemic area were fitted with logistic curve. The likelihood of occurrence of VT or VF is increased as the weight percentage of ischemia area goes up.

Animals↗
PubMed1992

[Structure determination of saponin IX and X from Dipsacus asper Wall].

Two new triterpenoid glycosides (IX and X) were isolated from the ethanol extracts of the roots of Dipsacus asper Wall. Their structures were deduced as 3-O-[beta-D-xylopyranosyl (1-->4)-beta-D-glucopyranosyl(1-->4)] [alpha-L-rhamnopyranosyl (1-->3)]-beta-D-glucopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->2)- alpha-arabinopyranosyl-hederagenin (IX) and 28-O-beta-D-glucopyranosyl(1-->6)- beta-D-glucopyranosyl ester of IX (X), based on spectral and chemical analysis.

Drugs, Chinese Herbal↗
PubMed1992

Molecular characterization of cloned variants of Coxiella burnetii isolated in China.

To study the molecular properties of Coxiella burnetii phase variants we cloned the phase variants of C. burnetii Qiyi (CBQY) strain by the red plaque technique. Three cloned strains, CBQYIC3 (phase I), CBQYIIC7 (phase II) and CBQYIIC5 (semirough-phase) were analysed by SDS-PAGE, immunoblot assay, plasmid isolation and agarose gel electrophoresis of DNA restriction fragments. The results suggest that the unique phase-dependent substance is a lipopolysaccharide and that most protein components of phase I and phase II cells are shared. No significant differences of DNA restriction fragments were found between clonal isolates of phase I and phase II C. burnetii CBQY strains. A plasmid of approximately 56 Kb was isolated from both phase I and phase II variants indicating that phase variation probably could not be attributed to its presence or absence.

Bacterial Proteins↗
PubMed1992

[Effects of tian-ma injection on myocardial ischemia and lipid peroxidation in rabbits].

Lipid peroxidation initiated by oxygen free radicals played an important role in the pathogenesis of coronary heart disease. The purpose of this study was to explore the effects of Tian-Ma (Gastrodia elata Bl.) injection on myocardial infarct size and lipid peroxidation by observing serum malondialdehyde (MDA) levels. Twenty-six New Zealand rabbits were divided into control group (n = 6), ischemic group (n = 10), and Tian-Ma treated group (n = 10). Left ventricular branch (LVB) of coronary artery was ligated at its middle third in ischemic and treated groups. LVB was not ligated in control group. Tian-Ma injection was given intravenously (1 mg/kg) every 8 hours after ligation in treated group for 48 hours. Precordial 12-lead ECG mapping was recorded before operation and at 3, 24 and 48 hours after occlusion. Hemodynamic changes (HR, LVP) were monitored before and 0.5, 3 and 48 hours after ligation. Serum MDA levels were determined by thiobarbituric acid spectrophotometry before operation, and 0.5, 3, 9, 24, and 48 hours after ligation. Dual staining technique was used 48 hours after ligation to determine the area at risk and infarct size. The results showed that Tian-Ma injection did not decrease sigma ST elevation (P greater than 0.05), but NQ was significantly lower during ischemia in treated group (P less than 0.01), Tian-Ma injection reduced the area at risk by 23.5% (P less than 0.05) and infarct size by 34.5% (P less than 0.01). Tian-Ma injection significantly decreased the levels of serum MDA 24 and 48 hours after occlusion (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗