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Biomedical subjects

Z Q Sun

Publications and source records attributed to Z Q Sun.

At least 19 recordsLinked to original sources
PubMed2006

[Significance of hepatitis B virus PreS1-Ag, PreS2-Ag, large protein, PreS2-Ab detection and the prediction of HBV DNA replication.].

BACKGROUND: To explore the significance of hepatitis B virus PreS1-Ag, PreS2-Ag, large protein (LP) detection and the prediction of viral replication. METHODS: PreS1-Ag, PreS2-Ag, LP and HBV markers were measured by enzyme linked immunosorbent assay (ELISA) in 201 cases of infected serum. Serum HBV DNA level was quantitatively detected by real-time polymerase chain reaction (PCR). RESULTS: There were significant differences in positive rate between the PreS1-Ag, PreS2-Ag, LP, and HBsAg; the positive rate of PreS2-Ag and LP were higher than that of the HBeAg. No significant differences were found in the positive rates between LP and the levels of HBV DNA and there was a positive correlation between quantitations of HBV DNA and HBV-LP. CONCLUSION: Serum PreS1-Ag, PreS2-Ag and LP were laboratory markers that can accurately reflect HBV DNA reproduction, and were helpful complementarity to traditional HBV M. There is a close correlation between the number of copies of HBV DNA and the levels of HBV-LP.

DNA Replication↗
PubMed2005

Nonspherical colloidal crystals fabricated by the thermal pressing of colloidal crystal chips.

Nonspherical colloids and their ordered arrays may be more attractive in applications such as photonic crystals than their spherical counterparts because of their lower symmetries, although such structures are difficult to achieve. In this letter, we describe the fabrication and characterization of colloidal crystals constructed from nonspherical polyhedrons. We fabricated such nonspherical colloidal crystals by pressing spherical polymer colloidal crystal chips at a temperature slightly lower than the glass-transition temperature (T(g)) of these polymer colloids. During this process, the polymer microspheres were distinctively transformed into polyhedrons according to their crystal structures, whereas the long-range order of the 3D lattice was essentially preserved. Because a working temperature lower than T(g) effectively prevented the colloidal crystals from fusing into films, the spherical colloidal crystals were transformed greatly under pressure, which lead to obvious change in the optical properties of colloidal crystals. Besides their special symmetry and optical properties, these nonspherical colloidal crystals can be used as templates for 2D or 3D structures of special symmetry, such as 2D nano-networks. We anticipate that this fabrication technique for nonspherical colloidal crystals can also be extended to nonspherical porous materials.

Journal Article↗
PubMed2004

The effect of a disastrous flood on the quality of life in Dongting lake area in China.

We carried out an epidemiological study to assess the impact of flood on the quality of life (QOL) of residents in the affected areas in China. We used a natural experiment approach, randomly selected 494 adults from 18 villages, which suffered from flooding as a result of embankments collapsing, 473 adults from 16 villages, which suffered from, soaked flood, and 773 adults from 11 villages without flood (control group). We used the Generic QOL Inventory-74 (GQOLI-74), social support scale, and questionnaires to assess the QOL of all study participants. The QOL was significantly poorer in soaked group (58.4) and (especially) in collapsed group (55.1) than in control group (59.5, p<0.001). Adjustment for potential confounding factors did not change the results. The impact of flood on QOL was stronger among farmers, seniors, persons with introvert personality, and residents with adverse life-events, whereas social support and extrovert personalities offset the negative impact of flood on QOL.

Adult↗
PubMed2001

Thyroid hormone increases pacemaker activity in rat neonatal atrial myocytes.

The effects of thyroid hormone (3,3',5-triiodo- L -thyronine, T3) on pacemaker activity were studied with electrophysiological and pharmacological approaches using spontaneously beating neonatal atrial myocytes cultured from 2-day-old rats. Treatment with T3 (10(-8)m) for 24-48 h led to a positive chronotropic effect. The beating rate of T3-treated cells was 244+/-19 beats/min and for control cells it was 122+/-10 beats/min (P<0.05). Action potentials were recorded and showed that the predominant effect of T3 was to increase the diastolic depolarization rate (99.5+/-9.8 in T3-treated group v 44.0+/-7.8 mV/s in untreated group). Some cells that exhibited pacemaker activity lacked a pacemaker current (I(f)) under voltage clamp conditions I(f)was recorded in 5 of 12 spontaneously active control cells and in 6 of 10 T3-treated cells. In those cells exhibiting the pacemaker current, the I(f)density was significantly larger in T3-treated cells (-7.9+/-2.6 pA/pF v-1.8+/-0.5 pA/pF in control). The L-type Ca2+ current density was similar in the two groups (at -7 mV, -7.5+/-1.5 in treated group v-8.6+/-1.0 pA/pF in control). In the presence of T3, the Na+-Ca2+ exchanger current (I(Na/Ca)) density was larger (e.g. at +60 mV, it was 4.8+/-0.5 v 3.5+/-0.2 pA/pF in control cells, P<0.05). As intracellular Ca2+ is extruded from the cell, the electrogenic Na+-Ca2+ exchanger causes a declining inward current, which may contribute to the pacemaker potential-this declining inward current was demonstrated using the action potential voltage clamp technique and was shown to be larger in T3-treated myocytes. Our data demonstrate that thyroid hormone enhances pacemaker activity and that this may be due in part to an increased Na+-Ca2+ exchanger activity.

Action Potentials↗
PubMed2001

Is the molecular composition of K(ATP) channels more complex than originally thought?

ATP-sensitive K+ (K(ATP)) channels are abundantly expressed in the heart and may be involved in the pathogenesis of myocardial ischemia. These channels are heteromultimeric, consisting of four pore-forming subunits (Kir6.1, Kir6.2) and four sulfonylurea receptor (SUR) subunits in an octameric assembly. Conventionally, the molecular composition of K(ATP) channels in cardiomyocytes and pancreatic beta -cells is thought to include the Kir6.2 subunit and either the SUR2A or SUR1 subunits, respectively. However, Kir6.1 mRNA is abundantly expressed in the heart, suggesting that Kir6.1 and Kir6.2 subunits may co-assemble to form functional heteromeric channel complexes. Here we provide two independent lines of evidence that heteromultimerization between Kir6.1 and Kir6.2 subunits is possible in the presence of SUR2A. We generated dominant negative Kir6 subunits by mutating the GFG residues in the channel pore to a series of alanine residues. The Kir6.1-AAA pore mutant subunit suppressed both wt-Kir6.1/SUR2A and wt-Kir6.2/SUR2A currents in transfected HEK293 cells. Similarly, the dominant negative action of Kir6.2-AAA does not discriminate between either of the wild-type subunits, suggesting an interaction between Kir6.1 and Kir6.2 subunits within the same channel complex. Biochemical data support this concept: immunoprecipitation with Kir6.1 antibodies also co-precipitates Kir6.2 subunits and conversely, immunoprecipitation with Kir6.2 antibodies co-precipitates Kir6.1 subunits. Collectively, our data provide direct electrophysiological and biochemical evidence for heteromultimeric assembly between Kir6.1 and Kir6.2. This paradigm has profound implications for understanding the properties of native K(ATP)channels in the heart and other tissues.

Adenosine Triphosphate↗
PubMed2001

Chromanol 293B inhibits slowly activating delayed rectifier and transient outward currents in canine left ventricular myocytes.

INTRODUCTION: Drugs that selectively inhibit the slowly activating component of the delayed rectifier potassium current (I(Ks)) are being considered as possible antiarrhythmic agents, because they produce more prolongation of action potential duration at fast rates with less transmural dispersion of repolarization compared with blockers of the rapidly activating component (I(Kr)). Although the chromanol derivative chromanol 293B has been shown to be relatively selective in blocking I(Ks) in some species, its selectivity is far from established. METHODS AND RESULTS: The present study uses whole-cell, patch-clamp technique to examine the selectivity of this compound for inhibition of I(Ks) in comparison with other repolarizing ionic currents, such as I(Kr), inward rectifier potassium current (I(Kl)), transient outward current (I(to)), and L-type calcium current (I(Ca-L)) in canine left ventricular mid-myocardial and endocardial cells. Chromanol 293B blocked I(Ks) with an IC50 of 1.8 microM and I(to) with an IC50 of 38 microM. Concentrations as high as 30 microM did not affect I(Kl), I(Kr), or I(Ca-L). Higher concentrations of chromanol 293B (100 microM) caused a slight, but statistically insignificant, inhibition of I(Kr). CONCLUSION: Our results indicate that chromanol 293B is a relatively selective blocker of I(Ks) in canine left ventricular myocytes.

Animals↗
PubMed2001

Evidence for functional role of epsilonPKC isozyme in the regulation of cardiac Na(+) channels.

Investigation of the role of individual protein kinase C (PKC) isozymes in the regulation of Na(+) channels has been largely limited by the lack of isozyme-selective modulators. Here we used a novel peptide-specific activator (epsilonV1-7) of epsilonPKC and other peptide isozyme-specific inhibitors in addition to the general PKC activator phorbol 12-myristate 13-acetate (PMA) to dissect the role of individual PKCs in the regulation of the human cardiac Na(+) channel hH1, heterologously expressed in Xenopus oocytes. Peptides were injected individually or in combination into the oocyte. Whole cell Na(+) current (I(Na)) was recorded using two-electrode voltage clamp. epsilonV1-7 (100 nM) and PMA (100 nM) inhibited I(Na) by 31 +/- 5% and 44 +/- 8% (at -20 mV), respectively. These effects were not seen with the scrambled peptide for epsilonV1-7 (100 nM) or the PMA analog 4alpha-phorbol 12,13-didecanoate (100 nM). However, epsilonV1-7- and PMA-induced I(Na) inhibition was abolished by epsilonV1-2, a peptide-specific antagonist of epsilonPKC. Furthermore, PMA-induced I(Na) inhibition was not altered by 100 nM peptide-specific inhibitors for alpha-, beta-, delta-, or etaPKC. PMA and epsilonV1-7 induced translocation of epsilonPKC from soluble to particulate fraction in Xenopus oocytes. This translocation was antagonized by epsilonV1-2. In native rat ventricular myocytes, PMA and epsilonV1-7 also inhibited I(Na); this inhibition was antagonized by epsilonV1-2. In conclusion, the results provide evidence for selective regulation of cardiac Na(+) channels by epsilonPKC isozyme.

Animals↗
PubMed2001

[Construction of CgA gene antisense transgenic mice].

In order to get CgA gene antisense DNA transgenic mouse, we constructed the CgA gene antisense DNA plasmid pCAS2C and microinjected it into the female pronucleus of fertilized mouse eggs, and transplanted them into oviduct of the foster. Every offspring of the fosters was determined by the PCR method. The positive mice had a 300 bp DNA electrophoresis band. We selected two male positive mice from 50 offspring survived of the pseudomother. Then, two positive mice crossed with normal mice respectively to reproduce offspring of F1. All offspring of F1 were determined by PCR to select positive offspring. Positive offspring of F1 carried only one allele of pCAS2C (heterozygous pCAS2C/-). Positive F1 offspring were selfcrossed, 1/4 offspring of F2 carrying two unites of one allele pCAS2C (pCAS2C/pCAS2C) are homozygous. Then, all offspring of homozygous F2 crossed with normal mice, could produce 300 bp DNA electrophoresis band by PCR. Total RNA of brain tissue of transgenic mouse was used to RT-PCR method, the 300 bp DNA product was obtained. The result indicates that the reading frame of CgA antisense DNA of pCAS2C has expressed in the transgenic mice.

Animals↗
PubMed2001

[Chromogranin A gene antisense transgenic mice and the tissue specific promoter of chromogranin A gene].

The vector pGAS1C-lacZ was constructed which contains cga promoter-lacZ and cga promoter-cga antisense cDNA two major parts. The pGAS1C-lacZ was integrated into genome of PC-12 cells and lacZ gene expressed in PC-12 cells. We cut the pGAS1C-lacZ with Xba I and Sal I to get rid of the framework of plasmid pGAS1C-lacZ, then microinjected the other part which contains antisense DNA into female pronucleus of the fertile mouse eggs. All injected fertile eggs were transplanted into the oviduct of foster so that the injected eggs developed normally. We selected transgenic mice by PCR, and got 14 transgenic founders. The founders were hybridized with normal mice respectively to reproduce the offspring F1 of founders. We executed all the founders and took their adrenal glands to dye with X-Gal respectively. Paraffin sections of the dyed adrenal glands were used to determine the level of lacZ expression in transgenic mice, so we selected two founders which adrenal glands were dyed deeply, and remained their offsprings. Taking different tissues from the transgenic mice to dye with X-Gal respectively, and we found the lacZ gene expressed in the adrenal gland and pancreas, but not in the muscle and adipose tissues. This result shows the neuroendocrine tissue specific promoter of Chromogranin A gene.

Animals↗
PubMed2000

[A case-control study on the risk factors for preterm delivery].

The risk factors for preterm delivery were analyzed with 1:2 matched case-control study by conditional logistic regression analysis. The result showed that the main risk factors for preterm delivery were neuroticism scores, premature rupture of the membranes, husband's smoking frequency during the third trimester of pregnancy, pregnancy induced hypertension, working strength and first-trimester vaginal bleeding. It is indicated that an examination before delivery and gaining weight during pregnancy are helpful to decrease the occurrence of preterm delivery.

Adult↗
PubMed2000

Amiodarone inhibits cardiac ATP-sensitive potassium channels.

INTRODUCTION: ATP-sensitive K+ channels (K(ATP)) are expressed abundantly in cardiovascular tissues. Blocking this channel in experimental models of ischemia can reduce arrhythmias. We investigated the acute effects of amiodarone on the activity of cardiac sarcolemmal K(ATP) channels and their sensitivity to ATP. METHODS AND RESULTS: Single K(ATP) channel activity was recorded using inside-out patches from rat ventricular myocytes (symmetric 140 mM K+ solutions and a pipette potential of +40 mV). Amiodarone inhibited K(ATP) channel activity in a concentration-dependent manner. After 60 seconds of exposure to amiodarone, the fraction of mean patch current relative to baseline current was 1.0 +/- 0.05 (n = 4), 0.8 +/- 0.07 (n = 4), 0.6 +/- 0.07 (n = 5), and 0.2 +/- 0.05 (n = 7) with 0, 0.1, 1.0, or 10 microM amiodarone, respectively (IC50 = 2.3 microM). ATP sensitivity was greater in the presence of amiodarone (EC50 = 13 +/- 0.2 microM in the presence of 10 microM amiodarone vs 43 +/- 0.1 microM in controls, n = 5; P < 0.05). Kinetic analysis showed that open and short closed intervals (bursting activity) were unchanged by 1 microM amiodarone, whereas interburst closed intervals were prolonged. Amiodarone also inhibited whole cell K(ATP) channel current (activated by 100 microM bimakalim). After a 10-minute application of amiodarone (10 microM), relative current was 0.71 +/- 0.03 vs 0.92 +/- 0.09 in control (P < 0.03). CONCLUSION: Amiodarone rapidly inhibited K(ATP) channel activity by both promoting channel closure and increasing ATP sensitivity. These actions may contribute to the antiarrhythmic properties of amiodarone.

Adenosine Triphosphate↗
PubMed2000

Effects of thyroid hormone on action potential and repolarizing currents in rat ventricular myocytes.

Thyroid hormones play an important role in cardiac electrophysiology through both genomic and nongenomic mechanisms of action. The effects of triiodothyronine (T(3)) on the electrophysiological properties of ventricular myocytes isolated from euthyroid and hypothyroid rats were studied using whole cell patch clamp techniques. Hypothyroid ventricular myocytes showed significantly prolonged action potential duration (APD(90)) compared with euthyroid myocytes, APD(90) of 151 +/- 5 vs. 51 +/- 8 ms, respectively. Treatment of hypothyroid ventricular myocytes with T(3) (0.1 microM) for 5 min significantly shortened APD by 24% to 115 +/- 10 ms. T(3) similarly shortened APD in euthyroid ventricular myocytes, but only in the presence of 4-aminopyridine (4-AP), an inhibitor of the transient outward current (I(to)), which prolonged the APD by threefold. Transient outward current (I(to)) was not affected by the acute application of T(3) to either euthyroid or hypothyroid myocytes; however, I(to) density was significantly reduced in hypothyroid compared with euthyroid ventricular myocytes.

4-Aminopyridine↗
PubMed2000

Amplified esterases B1 and A2-B2 in field populations of Culex pipiens from China.

The main organophosphate (OP) resistance mechanism in the Culex pipiens complex is increased activity of esterases A and B. Fourth-stage larvae from 2 field populations of C. pipiens from Gaomi and Kunming, China, were compared for tolerance to parathion, dichlorovos (OP), and bassa (carbamate) insecticides. Both populations were resistant to OPs but not to bassa. Starch gel electrophoresis indicated that elevated esterase activity was correlated with OP resistance. High frequencies of amplified esterase genes B1 and A2-B2 (0.85 and 0.50) were discovered in Gaomi and Kunming, respectively. However, only low levels of gene amplification were detected.

Animals↗
PubMed1999

New esterase enzymes involved in organophosphate resistance in Culex pipiens (Diptera: Culicidae) from Guang Zhou, China.

Organophosphate (OP) insecticides have been used widely to control Culex pipiens L. populations and this has led to the emergence of OP-resistance. Predominantly, resistance in Cx. pipiens is caused by over-production of nonspecific esterases, such as Est beta 1(1) and Est alpha 2(1)/beta 2(1). These esterases confer multiple resistance to organophosphorus and carbamate insecticides. To define the esterases in Chinese Cx. pipiens, restriction fragment-length polymorphism analysis was performed at the esterase beta locus. A new esterase haplotype (Est beta 8) was found. Starch gel electrophoresis indicated that Est beta 8 was coelevated with a novel Est alpha 8. This article reports Est alpha 8/beta 8 esterase-mediated resistance in Cx. pipiens complex.

Animals↗
PubMed1997

Expectancy of working life of mine workers in Hunan province.

From demographic mortality and disability of, in total, 424965 y from workers in 29 coal or coloured/metal mines in Human province of China during the period 1980-1984, we calculated the length of expected working life (EWL) as well as the life expectancy (EL) of the workers in the different types of mines and between those working on the surface and those working underground. The average life expectancy in the coal mines for those starting work at 15 y was found to be 58.91 y and 49.23 y for surface and underground workers respectively. In the coloured/metal mines they were 60.24 y and 56.55 y respectively. If only the mortality data was taken into account; for the coal mines, the EWL at the age of 15 y of surface workers and underground workers was 48.46 and 45.10 y respectively; whilst in the coloured/metal mines the figures were 48.25 and 45.99 y respectively. If both mortality and morbidity data is used the EWL at the same age and in the same population is for the coal mines 39.42 (surface workers) 25.54 (underground workers) and for the coloured/metal mines 42.05 (surface workers) and 30.02 (underground workers). The main causes of the lowered EWL of the underground workers were industrial accidents and pneumoconiosis which indicates that safety measures need to be increased and working conditions improved to protect underground workers.

Accidents, Occupational↗
PubMed1997

[Studies on neuro-immunologic regulation of senile rats by using the principle of replenishing qi and promoting blood circulation].

OBJECTIVE: To study the mechanism of delaying senility by using the principle of replenishing Qi and promoting blood circulation(RQPBC). METHODS: The following determinations were carried out in the natural-senile animals which have Qi deficiency and blood stasis Syndrome(24 month old rat) after the treatment. Hemorheological indexes, brain noradrenaline (NE), adrenocorticotropine(ACTH), beta endorphin, cortisol, estradiol, testosterone, interleukin-II (IL-2), tumour necrosis factor (TNF) in the blood, and rat spleen's lymphocyte transformation and induction of IL-2 and the activity of natural killer cells (NKC). RESULTS: The senile rat's above indexes decreased obviously (control: young rats), and by using this principle, all indexes were improved respectively. But these indexes in the young rats cannot be changed by applying this principle. CONCLUSION: The results indicated that this principle could improve senile body's regulation of neuro-immuno endocrinologic network and keep homeostasis.

Adrenocorticotropic Hormone↗
PubMed1996

Cellular and ionic mechanisms underlying erythromycin-induced long QT intervals and torsade de pointes.

OBJECTIVES: This study sought to elucidate the cellular and ionic basts for erythromycin-induced long QT syndrome. BACKGROUND: Erythromycin is known to produce long QTU intervals on the electrocardiogram (ECG) and to be associated with the development of torsade de pointes (TdP). The mechanisms responsible for the adverse effects of this widely used antibiotic are not well defined. METHODS: The present study used microelectrode and whole-cell patch-clamp techniques to assess the effects of erythromycin on epicardial, endocardial and M cells in transmural strips, arterially perfused wedges and single myocytes isolated from the canine left ventricle. RESULTS: In isolated strips, erythromycin (10 to 100 micrograms/ml) produced a much more pronounced prolongation of the action potential duration (APD) in M cells than in endocardial and epicardial cells, resulting in the development of a large dispersion of repolarization across the ventricular wall at slow stimulation rates. Erythromycin (50 to 100 micrograms/ml) induced early after depolarizations (EADs) in cells in the M (20%) but not epicardial or endocardial regions in transmural strips of ventricular free wall. Erythromycin (100 micrograms/ml) also caused APD prolongation and a transmural dispersion of repolarization, but not EADs, in intact arterially perfused wedges of canine left ventricle. These changes were attended by the development of a long QT interval on the transmural ECG. A polymorphic ventricular tachycardia closely resembling TdP was readily and reproducibly induced after erythromycin but not before. Whole-cell patch-clamp techniques, used to examine the effects of erythromycin on myocytes isolated from the M region, showed a potent effect of the drug to inhibit the rapidly activating component (IK(r)) but not the slowly activating component (IKs) of the delayed rectifier potassium current (IK). The inward rectifier current (IK1) was unaffected. CONCLUSIONS: Our data demonstrate a preferential response of M cells to the class III actions of erythromycin, due principally to the effect of the drug to inhibit IK(r) in a population of cells largely devoid of IKs. Our findings indicate that erythromycin thus produces long QT intervals as well as a prominent dispersion of repolarization across the ventricular wall, setting the stage for induction of TdP-like tachyarrhythmias displaying characteristics typical of reentry.

Action Potentials↗