Biomedical subjects

S Q Zhang

Publications and source records attributed to S Q Zhang.

At least 37 records · Page 2Linked to original sources

PubMed2000

[The enlarged translabyrinthine removal of large acoustic neuromas: 18 cases report].

OBJECTIVE: To investigate the surgical methods and results of enlarged translabyrinthine approach in the removal of large acoustic neuromas. METHOD: A large mastoidectomy involved complete exposure of sigmoid sinus, the dura behind the sinus for at least 1 cm, the superior petrosal sinus and the middle fossa dura. The jugular bulb was exposed and pressed downwards if necessary. The internal auditory meatus was skeletonized and uncovered for at least 270 degrees. The debulking of the tumor began inside the anterior and inferior poles in order to find the brainstem and the facial nerve root as early as possible, then the dissection of the nerve was performed medially to laterally. Intraoperative facial nerve monitoring and postoperative CT and MRI were performed in all cases. RESULT: Total removal was achieved in all 18 patients with tumors larger than 3 cm (mean size: 4.2 cm). There were no death as well as other complications such as intracranial infection and persistent cerebrospinal fluid leakage. There were no obvious cerebral sequela. The facial nerve was preserved both anatomically and functionally in 14 cases, with Grade I or II in 8 cases, Grade III or IV in 6 cases. Nerve interruption occurred in 4 cases who all had severe facial paralysis or nerve interruption before operation. 16 patients returned to work within 1-3 months. CONCLUSION: Total removal of large acoustic neuroma could be accomplished via the translabyrinthine approach, with good result of facial nerve function and minimum incidence of morbidity.

Adult↗

PubMed2000

[Survey of susceptibility of anopheline vectors to insecticides in a malaria mesoendemic area, Hubei Province].

OBJECTIVE: To determine the susceptibility of Anopheles anthropophagus and Anopheles sinensis to deltamethrin and DDT in an area where different counter-measures had been adopted. METHODS: The mortality of the vectors was examined by using the standardised WHO test. RESULTS: The mortality for tentative diagnostic dose in An. anthropophagus to deltamethrin were 83.8%, 83.7% and 84.7%, respectively in the areas where impregnated net had been used for 1 year or 3 years and DDT residual spraying had been carried out for 3 years, suggesting that An. anthropophagus was an initially resistant group. The LT50 were 8.69, 7.48 and 9.87 min, respectively. The mortality for tentative diagnostic dose in An. sinensis to deltamethrin and DDT were 76.5%, 57.0% and 79.0%, respectively in three survey areas, suggesting that An. sinensis was a resistant group. The LT50 were 12.0, 15.4 and 11.2 min, respectively. The mortality for tentative diagnostic dose in An. sinensis to DDT was 95.8% in impregnated net area, suggesting that An. anthropophagus was an initially resistant group. The LC50 was 0.73%. The mortality for tentative diagnostic dose in An. sinensis to DDT was 44%, suggesting that An. sinensis was a highly resistant group. The LC50 was more than 4%. CONCLUSION: A substantial use of insecticides in the rice paddy field has resulted in resistance of An. sinensis, whereas no apparent resistance of An. anthropophgus has been found.

Animals↗

PubMed2000

[Evaluation of prevalent status of kala-azar in endemic area of Hubei Province].

OBJECTIVE: To identify the diagnosis of 14 cases with "kala-azar" previously reported in Hubei Province since 1989 and to evaluate the present status of the disease. METHODS: Bone marrow smear, immunological test (LDTand IFAT), mouse inoculation, fungi culture, vector (Phlebotomus) and reservoir host (dog) survey. RESULTS: Among the 14 cases, 12 cases were progressive disseminated histoplasmois, one was an imported case and another one was a remnant skin type "kala-azar" case. An immunological survey was conducted during 1997-1999 in 25 townships located in 23 counties of 9 prefectures and cities. A total of 13,890 persons had been examined by LDT, the positive rate was 0.07%, no positive case was found among the persons under 40 years of age. During the survey, 1,756 persons had been examined by IFAT, the results were negative. No Phlebotomus chinensis had been found in the surveyed area. A total of 302 dogs were examined, no sick dog had been found. CONCLUSION: Kala-azar has been eradicated in Hubei Province.

Animals↗

PubMed1999

Effects of prolactin on sleep in cyclic rats.

We previously demonstrated that pregnancy-associated sleep enhancement is correlated with the daily surges of prolactin (PRL). However, in spite of a surge of PRL in the proestrous night, a reduction of nocturnal sleep occurs in phase with proestrus. Therefore, to clarify the physiological role of PRL in sleep regulation during the estrous cycle, time-course changes in sleep were analyzed in bromocriptine (CB-154)-treated and/or PRL-supplemented female rats. Sleep patterns characteristic of proestrus-to-estrus were not affected by the CB-154 treatment. In contrast, nocturnal rapid eye movement sleep (REMS) was significantly increased after the PRL supplementation. The CB-154 treatment diminished the REMS-enhancing effect of PRL. Thus, the results suggest that the endogenous PRL is not crucial for the regulation of sleep during the estrous cycle, while exogenous PRL can enhance REMS.

Animals↗

PubMed1999

Colony-stimulating factors in rapid eye movement sleep and non-rapid eye movement sleep regulation.

Although several cytokines are known to be somnogenic, no study has been conducted to examine whether colony-stimulating factors (CSF) affect sleep. Therefore, we studied the effects of granulocyte-macrophage CSF (GM-CSF) and macrophage CSF (M-CSF) on sleep in rats and their possible mechanism of action. At the dose of 10 pmol, GM-CSF or M-CSF significantly increased both non-rapid eye movement and rapid eye movement (REM) sleep or REM sleep only when infused intracerebroventricularly during the dark period. When injected locally in the hypothalamus, GM-CSF and M-CSF increased nitric oxide (NO) production. Thus, NOergic neural signals in the hypothalamus may take part in the somnogenic action of CSF.

Animals↗

PubMed1999

Inhibitory effect of MAP kinase antisense oligonucleotide on angiotensin II-induced c-myc gene expression and proliferation of rat cardiac fibroblast.

AIM: To investigate the inhibitory effect of down-regulating mitogen activated protein kinase (MAPK) on c-myc gene expression and further on cardiac fibroblast proliferation. METHODS: Cultured neonatal rat cardiac fibroblasts was pretreated with a phosphorothioate-protected 17-mer antisense MAPK oligodeoxynucleotide (ODN) directed against the initiation of translation sites of the p42 and p44 MAPK isoforms by liposomal transfection. A 17-mer sense and mismatch sequence MAPK ODN were used as controls. After liposomal transfecting, cells were exposed to angiotensin II (Ang II) 10 nmol.L-1 for 5 min and then harvested in lysis buffer. MAPK activity was measured by Western blot and P-81 phosphocellulose filter paper method by using [gamma-32P]ATP and myelin basic protein as substrates. c-myc mRNA expression stimulated by Ang II for 30 min was measured by Northern blot. DNA synthesis and collagen protein synthesis induced by Ang II for 24 h were measured by [3H]thymidine incorporation and [3H]Proline incorporation, respectively. RESULTS: Antisense ODN 0.2 mumol.L-1 reduced Ang II-induced MAPK activities by 72%, MAPK protein expression by 80%, and suppressed c-myc mRNA expression by 97%, respectively. [3H]thymidine incorporation and [3H]proline incorporation in Ang II-induced cardiac fibroblast were inhibited by 59% and 58%, respectively. CONCLUSION: A 17-mer MAPK antisense oligonucleotide directed againsts the initiation of translation sites of MAPK could specifically inhibit Ang II-stimulated cultured neonatal rat cardiac fibroblast proliferation through down-regulating MAPK activity and further depleting c-myc mRNA expression.

Angiotensin II↗

PubMed1999

[Direct gene transfer into rabbit peripheral nerve in vivo].

OBJECTIVE: To probe the possibility of direct transfer of exogenous gene into peripheral nerve and its following expression in vivo. METHODS: The PCMV beta plasmid containing cytomegalovirus (CMV) promoter and Escherichia Coli (E. Coli), beta-Galactosidease (beta-Gal) structural gene (lacZ gene) was constructed and injected into the rabbit sciatic nerve. The control group was injected PBS solution. The injected nerves were sampled and tested by beta-Gal enzyme activity assay of the 5-bromo-4-chloro-3-indolyl-beta-D-galactoside and beta-Gal histochemical stain. RESULTS: In the control group, no beta-Gal enzyme activity was detected in the different stages after operation, and beta-Gal histochemical stains showed positive. In the experimental group, enzyme activity could be detected from 2 days to 30 days after operation, and the histochemical stains showed negative. CONCLUSION: The exogenous gene can be transferred into peripheral nerve and expressed with bioactivity, thus the gene therapy to accelerate the recovery of nerve is practical.

Animals↗

PubMed1998

An animal model for pregnancy-associated sleep disorder.

We studied basic sleep changes in pregnant rats in order to understand how pregnancy alters sleep. In the rat, pregnancy increased nocturnal nonREM sleep across the entire period but increased REM sleep only in the early period. By the end of pregnancy, diurnal sleep was decreased, showing that pregnancy in rats causes biphasic sleep changes as it does in humans. Termination of pregnancy returned the enhanced sleep to baseline as in the estrous cycle. Therefore, significant changes in the pattern of sleep occurred during pregnancy in rats, suggesting that the animal model may contribute to understanding the mechanism of sleep disorders related to human pregnancy.

Animals↗

PubMed1996

Intracellular location of the Saccharomyces cerevisiae CDC6 gene product.

The CDC6 gene product from Saccharomyces cerevisiae is required for transition from late G1 to S phase of the cell cycle. We have investigated the subcellular localization of the CDC6 protein in yeast to explore where Cdc6p exerts its gene function (s). Using affinity-purified sera we localized Cdc6p to the cytoplasm and the nuclear matrix by both subcellular fractionation and indirect immunofluorescence microscopy. The nuclear localization was confirmed to be in the nuclear scaffold by the low-salt extraction method. The Cdc6p cannot be detected in the mitochondrial or plasma membrane fractions. Using indirect immunofluorescence, we found that a subpopulation of Cdc6p migrated into the nucleus after G1/S transition and diminished after M phase, suggesting its temporal role in nuclear DNA replication. The predicted Cdc6p polypeptide contains a conserved nuclear localization, 27PLKRKKL33, similar to that of the SV40 large T antigen and other nuclear proteins. To test whether this peptide segment plays a role in mediating nuclear transport, we have carried out site-directed mutagenesis to alter the conserved 29Lys to Thr and Arg. The wild-type nuclear localization signal of Cdc6p was found to mediate the LacZ reporter gene fused to CDC6 efficiently to the nucleus, but not the mutated versions of the nuclear localization motif. The results suggested that 29Lys is important in mediating nuclear localization, the 29Thr and 29Arg mutant versions of the CDC6 gene were also unable to complement the cdc6 temperature-sensitive mutant. However, when these mutants were expressed from a multicopy plasmid, the mutated genes could complement the mutation. Similar results were obtained in the cdc6-disrupted cells. Taken together, we suggest that (i) Cdc6p is predominantly located in the cytoplasm, (ii) the nuclear entry of Cdc6p is cell cycle dependent, and (iii) nuclear entry of Cdc6p is mediated by its nuclear localization signal. The presence of Cdc6p in both the nucleus and the cytoplasm suggests a model that Cdc6p exerts its gene function in DNA replication and mitotic restraint in the cell cycle.

Amino Acid Sequence↗

PubMed1996

Hepatitis A in a Chinese urban population: the spectrum of social and behavioural risk factors.

BACKGROUND: Viral hepatitis is a major public health problem in China. Hepatitis A infections represent a substantial proportion of these, particularly in urban centres. Little is known about the social and behavioural factors in the urban household environment that influence the transmission of hepatitis A. METHODS: We conducted a register-based case-control study to investigate the risk factor patterns for hepatitis A in the general population of the City of Wuhan, in the PR China. Cases were selected from district-based health registers. One control, matched for sex and age, was identified from the case's neighbourhood. Home-based interviews combined with household observation were performed to obtain information on social, behavioural and economic risk factors and the household's indoor and outdoor environment. Analysis included conditional logistic regression. RESULTS: Hepatitis A infection was associated with a variety of social and household-related factors, like handwashing habits (after working in the garden: adjusted odds ratio [OR] = 8.24, 95% confidence interval [CI]: 1.5-44.2, before food preparation: OR = 4.68, 95% CI: 1.8-12.0; before eating: OR = 4.92, 95% CI: 1.5-15.7), and the source of fresh vegetables (OR = 3.90, 95% CI: 1.6-9.8). Hygiene in the kitchen and the household surroundings and the disposal of children's stools in vegetable gardens or refuse pits were significantly associated with univariate analysis only. The lack of possession of luxury consumer items as a surrogate indicator for income was significantly associated with the disease (OR = 2.47, 95% CI: 1.0-6.1). The study clearly established that exposure to health and hygiene education was less in the group of hepatitis A cases when compared to healthy controls (OR = 2.80, 95% CI: 0.9-8.3). CONCLUSION: The results of this study underline how social and behavioural factors are important determinants for hepatitis A in urban Chinese populations. These issues could be addressed by appropriate health and hygiene education targeted at high risk groups, and by strengthening existing procedures for monitoring and control of food hygiene.

Adolescent↗

PubMed1996

Pregnancy-associated sleep changes in the rat.

Sleep disorder during the course of pregnancy has been recently recognized in humans. However, the underlying mechanism of pregnancy-associated sleep disorder remains undetermined, and sleep changes even during normal pregnancy have not been fully understood. To describe the effects of pregnancy on sleep, sleep-wake patterns before and after fertile mating were compared in an animal model. Baseline recordings of sleep and brain temperature were made throughout a normal 4-day estrous cycle in female rats. After the rats became pregnant, the recordings continued across the entire pregnant period. Compared with baseline sleep before mating, both non-rapid eye movement sleep and rapid eye movement sleep increased significantly from the first night of pregnancy. Although rapid eye movement sleep returned to the baseline level from midpregnancy, nocturnal non-rapid eye movement sleep stayed enhanced during the entire pregnant period. Daytime sleep fluctuated toward the end of pregnancy. Brain temperature was elevated during the early period of pregnancy but did not correlate with enhanced sleep. The results suggest that physiological changes in different stages of pregnancy may contribute to the regulation of maternal sleep and temperature.

Animals↗

PubMed1996

[Pharmacokinetics and disposition of triptonide in rats].

Triptonide, isolated from Tripterygium wilfordii Hook., was found to show significant antiinflammatory, immunosuppression and antitumor activities. A RP-HPLC method was applied to determine the plasma concentration of triptonide at different times in rats. Concentration-time curves after i.v., 0.7, 1.4 and 2.8 mg.kg-1 of triptonide were fitted to a two-compartment open model with T1/2 alpha of 0.167-0.195 h and T1/2 beta of 4.95-6.49 h. The area under curves (AUCs) were linearly related to the dosages (gamma = 0.9894). Systematic clearances (CLs) were independent of dosages. Mean residence time (MRT) of the three doses was 3.26-5.14 h by noncompartmental (the statistical moment method) analyses. The tissue distribution of triptonide in rats appeared to be wide throughout the body. The triptonide levels were high in the lung and liver, moderate in the heart, kidney, spleen and muscle and low in the testis, intestine and brain. Data of the urine and bile excretion indicated that only a small percent of unchanged triptonide was excreted. Plasma protein binding of triptonide rate was about 75%.

Animals↗

PubMed1995

Sleep patterns in cyclic and pseudopregnant rats.

In order to clarify the relationship between sleep and reproductive activities, time-course changes in sleep were analyzed in normal female rats. The state of sleep-wakefulness was continuously monitored for 4 weeks including two-consecutive 4-day estrous cycles, a 12-day pseudopregnant period and a subsequent 4-day cycle. Sleep patterns in estrous cycle were characterized by a marked reduction in nocturnal non-rapid-eye-movement sleep (NREMS) and rapid-eye-movement sleep (REMS) at proestrus. A significant increase in nocturnal NREMS and REMS occurred immediately after the induction of pseudopregnancy by sterile mating, lasting for the whole pseudopregnant period for NREMS and during the early and mid period for REMS. In contrast, diurnal REMS tended to decrease towards the end of pseudopregnancy. The circadian rhythm of brain temperature exhibited no reproductive activity-dependent change. The dynamic changes in sleep may correlate alterations in neuroendocrine activities specific to estrous cycles and pseudopregnancy.

Animals↗

PubMed1995

Pulsed field gel electrophoresis labeling method to study the pattern of Saccharomyces cerevisiae chromosomal DNA synthesis during the G1/S phase of the cell cycle.

Yeast Saccharomyces cerevisiae is an excellent model to study eukaryotic DNA replication. Since yeast lacks thymidine kinase, it is difficult to assay DNA synthesis. In this report, a novel approach called the pulsed field gel electrophoresis (PFGE) labeling method is used to investigate yeast chromosomal DNA synthesis. In this method, yeast cells are first labeled by 32P in vivo and chromosomal DNA molecules are then resolved by pulsed field gel electrophoresis. A linear 32P labeling of chromosomal-size DNA molecules can be observed up to 100 min in an asynchronized culture. In an alpha-factor arresting-and-releasing synchronized culture, we observed that 32P can be rapidly taken up in the S phase. Our results show that all of the chromosomes are labeled at approximately the same time (within a 15-min interval), suggesting that the temporal order of all chromosomal DNA synthesis is synchronized in the S phase. Cell cycle blockers were used to arrest the yeast cultures to study DNA synthesis that coincides with cell cycle analysis. Our results show that alpha-factor and hydroxyurea block the cell cycle at the late G1 and S phases, respectively, resulting in the failure of DNA synthesis. Nocodazole blocks the cell cycle after the S phase and thus shows no effect on chromosomal DNA synthesis. Since the PFGE labeling method is highly specific to chromosomal DNA synthesis, we used it to examine the DNA synthesis pattern in various cell cycle mutants. All of the G1/S cdc mutants tested, cdc4, 6, 7, 8, 17, 2, and 9, cannot label the chromosomal size of DNA molecules; but the G2/M cdc mutant cdc13 can.(ABSTRACT TRUNCATED AT 250 WORDS)

Agglutinins↗

PubMed1995

Sucrose: a solute that accumulates in the guard-cell apoplast and guard-cell symplast of open stomata.

Stomatal conductances of Vicia faba leaves were recorded over a day. Coordinately, (a) guard cells dissected from leaflets were assayed, providing total sucrose content, and (b) guard cells dissected from rinsed epidermes were also assayed, providing symplastic sucrose content. Compared with that of pre-dawn samples, apoplastic sucrose content increased 4.8-5.2 x (2 experiments), reaching 1,130-1,300 fmol.guard-cell-pair-1 at midday, when conductance was highest (ca. 0.13 mol.m-2.s-1); symplastic sucrose content increased 2.5-3.5 x, reaching 350-390 fmol.guard-cell-pair-1. Thus, there is a correlation between transpiration and guard-cell sucrose content, particularly that portion localized to the apoplast. Moreover, apoplastic sucrose is apparently a source of guard-cell nutrition and, possibly, osmoticum.

Carbon Dioxide↗

PubMed1995

Temporal and spatial distributions of yeast nucleoside diphosphate kinase activities and its association with the Cdc8p.

Nucleoside diphosphate kinase (E.C. 2.7.4.6.) is a broad substrate-specific enzyme that catalyzes the phosphorylation of nucleoside diphosphates to the corresponding triphosphates in nucleic acid biosynthesis. In this report, we investigate its spatial and temporal distributions in yeast to understand how the enzyme exerts its gene function(s). Our results show that the enzyme is predominantly cytoplasmic. A substantial amount of enzyme activity (40-50%) may be associated with the cell membrane. Less than 1% of total activity was detected in the nuclear fraction. Approximately 3% was found in the mitochondrial fraction. When yeast cultures were synchronized, we found that Saccharomyces cerevisiae nucleoside diphosphate kinase did not show cell cycle periodicity, as Schizosaccharomyces pombe enzyme did. To explore its link with DNA synthesis, we investigated its relationship with the Cdc8p (dTMP kinase). We demonstrated a physical interaction between these proteins in vitro, as evidenced that the GST:Cdc8p protein affinity column could retain a subpopulation of nucleoside diphosphate kinase activity from yeast crude extract. Furthermore, when GST:Cdc8p protein was expressed in yeast, the protein could bind to the glutathione-agarose, along with nucleoside diphosphate kinase, suggesting that there is an interaction between GST:Cdc8p and nucleoside diphosphate kinase in vivo. Our results provide evidence for at least a two-enzyme complex that may well facilitate nucleotide channeling in the cell.

Cell Cycle↗

PubMed1994

Lessened malate inhibition of guard-cell phosphoenolpyruvate carboxylase velocity during stomatal opening.

Leaflets of Vicia faba with closed stomata or with opening stomata were freeze-dried. Excised guard-cell pairs were assayed individually under suboptimal conditions (pH 7.1 and subsaturating substrate) for phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) using quantitative histochemical procedures. L-Malate, 400 microM, significantly inhibited guard-cell PEPC activity of closed stomata but not that of opening stomata. We postulate that the lessened sensitivity of guard-cell PEPC activity to malate inhibition is an important regulatory feature of stomatal opening, which is associated with malate accumulation.

Fabaceae↗

PubMed1994

Human dTMP kinase: gene expression and enzymatic activity coinciding with cell cycle progression and cell growth.

dTMP kinase (E.C.2.7.4.9.) catalyzes the phosphorylation of dTMP to the corresponding diphosphate. This enzyme is essential for DNA synthesis in vivo and is an important intermediate enzyme in the pathway of many pyrimidine analog drugs. In this report, we describe the isolation of the human dTMP kinase gene by functional complementation of a Saccharomyces cerevisiae cell cycle mutant, cdc8. The cDNA sequence revealed an open reading frame that encodes a protein with the molecular weight of 23,806. The deduced protein sequence was compared to known dTMP kinase sequences from different organisms. Although functionally complementary and structurally conserved, expressed human dTMP kinase in yeast shows little enzymatic activity. In contrast, active human dTMP kinase can be expressed from the gene cloned into the baculovirus expression system, as evidenced by increased enzymatic activity by four- to five-fold. Unlike yeast dTMP kinase, human dTMP kinase does not contain a cysteine residue after the conserved glycine-rich loop, but its enzymatic activity is still affected by the sulfhydryl inhibitor, 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB). The levels of dTMP kinase mRNA and its enzymatic activity fluctuate during the cell cycle, peaking at the S phase. Thus, like Saccharomyces cerevisiae CDC8 (encoding dTMP kinase), the human homolog mRNA and enzymatic activity are also cell cycle regulated. We have also examined four neuroblastoma cell lines for dTMP kinase mRNA levels and its kinase activities, which appear to vary according to cell growth rate. Our results suggest that the expression of the dTMP kinase gene and its activity coincide with various stages of cell growth. The identification of the human dTMP kinase gene and expression of its product in the baculovirus expression system should facilitate study of the mechanism of gene regulation and its role in pyrimidine metabolism.

Amino Acid Sequence↗