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Biomedical subjects

S Zhou

Publications and source records attributed to S Zhou.

At least 307 records · Page 17Linked to original sources
PubMed1998

[Determination of azathiopurine and 6-mercaptopurine in serum by reversed-phase high performance liquid chromatography].

A method for simultaneous determination of azathiopurine(AZP) and its metabolite 6-mercaptopurine (6-MP) concentration in serum has been developed. Reversed-phase high performance liquid chromatography with gradient elution and dual wavelength detection was employed. After protein precipitation with acetonitrile, the serum sample was evaporated to dryness with a gentle N2 stream at 37 degrees C and 100 microL of the mobile phase were added to dissolve the residue. After centrifugation, 20 microL of the supernatant was injected directly into the HPLC. The detection wavelength was set at 278 nm (AZP) and 325 nm (6-MP). The internal standard was metronidazole. The minimum detectable mass concentration for both AZP and 6-MP in serum was 5 mg/L. The average recoveries were (100.6 +/- 4.2)% for AZP and (102.4 +/- 4.5)% for 6-MP.

Azathioprine↗
PubMed1998

[The transcriptional regulation of the TCA1 elements and their effects on morphogenesis of Candida albicans].

We have cloned two copies of retrotransposon-like elements Tca1-1 and Tca1-2 (Transposon Candida albicans) from Candida albicans strain SC5314. Comparing the restriction maps of the two genomic fragments, similar patterns were observed. The two composite elements were transcribed into an approximately unit length 6 kb RNA. The expression of this transcript was greatly increased when cells were grown at 25 degrees C versus 37 degrees C. Deletion of the partial or complete intervening region of the Tca1-1 element causes the morphogenetic variation of the cells. The morphogenetic variation is in cooperation with the expression of the URA3 gene.

Candida albicans↗
PubMed1998

[The design of a fiber optic hygrometer using in patient monitor].

Fiber optic sensor is a kind of newly developed sensory technology in recent ten years. With intrinsic security and wide application, it is superior to the traditional point sensors. This paper presents the design of a kind of fiber optic hygrometer using in patient monitor.

Equipment Design↗
PubMed1998

[Preparation of 5-fluoruracil-poly-alpha, beta(2-hydroxyethy1)-DL-asparamide and in-vivo release in rabbit].

A polymer release drug was prepared by poly-alpha, beta-(2-hydroxyethyl)-DL-asparamide(PHEA) and 5-fluorouracil. As a model drug 5-fluorouracil was conjugated into the biodegradable polymer by chemical bond. The released drug was determined to be about 37.1% (w/w) and it was characterized by IR spectrum and differential scanning calorimetry (DSC). Two forms of drugs, rod and suspension were prepared and in vivo release experiment were carried out in rabbits. The experimental result showed that the rod form of drug can in some degree reduce initial burst.

Animals↗
PubMed1998

[An epidemiologic retrospective study of 1693 maxillofacial injuries].

A 10-year review of 1693 maxillofacial injuries was presented with respect to age, sex, cause of injury, pattern of fracture, and associated systemic injuries. The majority of fractures in maxillofacial region were found in males, the most prevalent age ranged from 21 to 40 years. The leading cause of facial trauma was traffic accidents. Mandible fracture outranked zygomatic and maxillary fracture. Multiple fractures were more common than single fracture. The average number of fractures for each patient was 1.7. Accompanied injuries to brain and skull happened in almost half patients, which were more often than other part of the body. There was a higher incidence that midfacial fractures coincided with brain and skull damage.

Accidents, Traffic↗
PubMed1998

[A new method for evaluating malaria surveillance effectiveness--establishment and application of an index system].

AIM: To establish a comprehensive index system which is suitable for evaluating the effectiveness of malaria surveillance schemes. METHODS: Delphi method was used to screen the existed effectiveness evaluation indices by experts to determine key indices and weighted coefficients. RESULTS: Three indices, i.e. autochthonous incidence, ratio of cases detected (ROCD) and ratio of introduced/imported cases were selected. Their weighted coefficients were 0.36, 0.31 and 0.33, respectively. An index system named the malaria surveillance effectiveness index (MSEI) was built up and formulated as [formula: see text] which was applied to study cost-effectiveness of the two malaria surveillance schemes (A and B). According to the formula, the MSEIs in the study areas using the schemes A and B were 48.56 and 45.93, respectively. However, the cost for increasing a score of MSEI by implementing the scheme A was four times as high as that by implementing the scheme B. CONCLUSION: The MSEI is practicable for evaluating the overall effectiveness of malaria surveillance schemes, especially in the cost-effectiveness analysis and health-economic evaluation.

China↗
PubMed1998

[Ultrastructure of Schistosoma japonicum sperm].

AIM: To understand the ultrastructure of Schistosoma japonicum sperm. METHODS: Testis and oviduct were cut from male and female of S. japonicum respectively, location was assured by observing with microscope. Specimens preparation for transmission electron microscope were made by traditional way. RESULTS: The sperm of S. japonicum includes two parts: a head and a single tail. The elongated ovoid head measures by 6.2 x 1.4 microns, lacking an acrosome, rounding anteriorly and tapering posteriorly. A prominent anterior mass of mitochondria lies beneath the plasma membrane. A layer of microtubes under the plasma membrane are parallel with long axis of the head. A coil of longitudinal microtubes were present beneath the plasma membrane. The nucleus is largely electron-opaque with some electron-lucent patches or less electrondense material. The tail is a single flagellum with a unique axoneme, which originated from a centriole. The axoneme in main part of the flagellum (including middle and posterior parts of the tail) consists of nine doublets and a single diffuse central structure, forming 9 x 2 + <<1>> type. But the axoneme in the transition area (anterior part of the tail) lacks central material, forming 9 x 2 + 0 type. CONCLUSION: The sperm ultrastructure in the schistosomes is homogeneous, but differs distinctly from those trematodes of other Digenea.

Animals↗
PubMed1998

[Studies on dynamic changes of SOD and MDA in cultured cells from Schistosoma japonicum schistosomula].

AIM: To observe the dynamic changes of superoxide dismutase(SOD) and maldondialdehyde(MDA) in cultured cells from Schistosoma japonicum schistosomula and to explore the degeneration process of cultured cells. METHODS: Pyrogallol method and thiobarbituric acid method were used to determinate the levels of SOD and MDA, respectively, in the cells cultured for 0-54 days. RESULTS: SOD in the cells reached a peak level on d12 of the early stage of culture and then decreased. The MDA levels in the cultures cells ascended gradually, and had two peaks on d18 and d48, during the period of culture. CONCLUSION: The cultured cells from S. japonicum schistosomula degenerated progressively.

Animals↗
PubMed1998

[An experimental study on limbal stem cells autograft transplantation with cryopreservation].

PURPOSE: The viability of limbal stem cells with cryopreservation and the treatment effect with cryopreserved limbal autograft transplantation for ocular surface disorders (OSDs) of stem cells deficiency in rabbits. METHODS: Limbal grafts included 2 mm of peripheral cornea and 2 mm of conjunctiva and OSDs models of corneal stem cells deficiency were created in right eyes of 12 rabbits. The grafts were cryopreserved in -196 degrees C liquid nitrogen by program-controlled Bio-Freezer. The limbal autograft transplantations for ocular surface reconstruction were performed after cryopreserved 60 days and 30 days. RESULTS: The stem cells deficiency result in corneal epithelium delay healing. Seven of 12 eyes were healed post-operative 22-26 days with a mean time of 24 +/- 1 days and four eyes with recurrent erosion. The swelling and neovascularization appearing with a mean time of 5 +/- 1 days were discovered. The cryopreserved limbal autograft transplantation can increase corneal epithelial healing with a mean time of 10 +/- 2 days. It was observed that corneal stromal swelling and neovascularization were markedly decreased, and neovascularization of two eyes were disappeared. CONCLUSIONS: Cryopreservation in liquid nitrogen can preserve the viability of limbal stem cells, and provide viable limbal grafts to treat OSDs in clinical patients.

Animals↗
PubMed1998

Effects of muscle fatigue and temperature on electromechanical delay.

The effect of repeated maximal isometric knee extensions on electromechanical delay (EMD) and associated muscle temperature changes were investigated on seven college aged subjects. The exercise produced a significant reduction in muscle contraction force, rate of force development and muscle conduction velocity, whilst the muscle temperature increased by 2.1 degrees C. The EMD increased from a pre-exercise value of 38.4 (SEM 3.4) ms to 55.7 (SEM 3.4) ms post-exercise. In an attempt to evaluate the effect of muscle temperature on EMD, hot and ice-water bags were placed on the quadriceps muscle to alter muscle temperature. The EMD in isometric maximal knee extension was measured at 38, 36, 34, 32 and 30 degrees C. The results showed that the EMD elongated at muscle temperatures either lower or higher than 36 degrees C. It was speculated that the increased muscle temperature might contribute to 20-25% of the EMD elongation found during the fatiguing intermittent exercise. The information of the effects of muscle temperature on EMD could be useful when evaluating the effects of strenuous exercise, in which a substantial muscle temperature change might occur, on the time delay between myoelectrical activity and force generation.

Adult↗
PubMed1998

Correlations between peak power output, muscular strength and cycle time trial performance in triathletes.

OBJECTIVE: To examine the relationship between the peak power output (Wmax), peak oxygen uptake (VO2peak), lower limb muscular strength and cycling time (CT) during a short course triathlon race. EXPERIMENTAL DESIGN: The study involved a cross-sectional analysis involving both physiological and biomechanical variables. SETTING: Testing was performed at the exercise physiology and biomechanics laboratory, School of Exercise Science and Sport Management, Southern Cross University, Lismore, Australia. PARTICIPANTS: Ten male triathletes who had been endurance cycle training for a minimum of 12 months prior to the commencement of the study. MEASURES: Subjects completed a maximal incremental cycle test as well as a series of muscular function tests including a 6-s cycle test, a concentric isoinertial squat jump as well as an isokinetic leg extension test performed at velocities of 60 degrees (s-1, 120 degrees (s-1 and 180 degrees.s-1. In addition, each subject also participated in a triathlon race of distance 1.5 km swim, 40 km cycle and 10 km run. RESULTS: A significant correlation existed between CT and absolute VO2 peak and Wmax. However, no significant correlations were found between the results of the muscular function tests and the incremental cycle test as well, as CT during the triathlon race. CONCLUSIONS: Wmax and WDmax are useful variables in assessing cycle performance in triathletes. However, the importance of muscular strength of the lower limbs may be minimal in overall cycle performance during a short course triathlon race.

Acceleration↗
PubMed1997

Purification, cDNA cloning, and gene mapping of the small subunit of human DNA polymerase epsilon.

HeLa DNA polymerase epsilon (pol epsilon), possibly involved in both DNA replication and DNA repair, consists of a catalytic subunit of 261 kDa and a tightly bound peptide with a relative molecular mass of 55 kDa. The cDNA of the 261-kDa polypeptide has been independently cloned, sequenced, and then overexpressed in insect cells to give a soluble, but catalytically unstable protein, suggesting that the small subunit of HeLa pol epsilon might be important for stability. HeLa pol epsilon has been isolated by immunoaffinity purification to obtain sequence information which enabled the cloning of a full-length human cDNA encoding the small subunit. The clone encoded nine proteolytic peptides obtained from the subunit. The 59,434-Da predicated polypeptide has 26% identity and 44% homology to the yeast pol epsilon 80-kDa subunit, DPB2. Using fluorescence in situ hybridization, the human pol epsilon p59 locus (DPE2) was assigned to chromosome 14q13-q21.

Amino Acid Sequence↗
PubMed1997

Sustained increase in intracellular free calcium and activation of cyclooxygenase-2 expression in mouse hepatoma cells treated with dioxin.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a non-genotoxic environmental pollutant that causes multiple adverse effects in experimental animals and in humans. We show here that TCDD treatment of mouse hepatoma cells causes a rapid mobilization of intracellular calcium both in wild type Hepa-1 cells and in its c2 variant, a cell line that has highly reduced levels of functional aromatic hydrocarbon (Ah) receptor (AHR). In wild type cells, but not in the c2 variant, TCDD treatment leads to a sustained elevation of cytosolic free calcium. TCDD also induces elevated levels of cyclooxygenase-2 (COX-2) mRNA in wild type and in c37, a CYP1A1-deficient cell line, but not in c2 cells. Induction of Cox-2 is in fact dependent on the presence of a functional Ah receptor, since it can be blocked by antisense oligonucleotides to Ah receptor mRNA. Most likely as a consequence of Cox-2 induction, we find a significant increase in the level of 12-hydroxyheptadecatrienoic acid (12-HHT) secreted from TCDD-treated Hepa-1 cells. In addition, we observe elevated levels of 6-keto prostaglandin F1alpha in c2 cells and high levels of secreted prostaglandin F2alpha in c2, c37 and c4, the variant cell line lacking aromatic hydrocarbon nuclear translocator protein. These data suggest that Cox-2 activation by TCDD leads to the release of prostaglandins, eicosanoids and other mediators which may have an important role in the biological and toxic effects of TCDD.

Animals↗
PubMed1997

Long-term correction of obesity and diabetes in genetically obese mice by a single intramuscular injection of recombinant adeno-associated virus encoding mouse leptin.

The ob/ob mouse is genetically deficient in leptin and exhibits a phenotype that includes obesity and non-insulin-dependent diabetes mellitus. This phenotype closely resembles the morbid obesity seen in humans. In this study, we demonstrate that a single intramuscular injection of a recombinant adeno-associated virus (AAV) vector encoding mouse leptin (rAAV-leptin) in ob/ob mice leads to prevention of obesity and diabetes. The treated animals show normalization of metabolic abnormalities including hyperglycemia, insulin resistance, impaired glucose tolerance, and lethargy. The effects of a single injection have lasted through the 6-month course of the study. At all time points measured the circulating levels of leptin in the serum were similar to age-matched control C57 mice. These results demonstrate that maintenance of normal levels of leptin (2-5 ng/ml) in the circulation can prevent both the onset of obesity and associated non-insulin-dependent diabetes. Thus a single injection of a rAAV vector expressing a therapeutic gene can lead to complete and long-term correction of a genetic disorder. Our study demonstrates the long-term correction of a disease caused by a genetic defect and proves the feasibility of using rAAV-based vectors for the treatment of chronic disorders like obesity.

Animals↗
PubMed1997

Opioid receptors on peripheral sensory axons.

Opioid receptors have been demonstrated by light microscopic techniques in fine cutaneous nerves in naive animals. The present study extends these findings by showing that 29 and 38% of unmyelinated cutaneous sensory axons can be immunostained for mu- or delta-opioid receptors respectively. Local cutaneous injection of DAMGO, a mu-opioid ligand, ameliorates the nociceptive behaviors caused by local cutaneous injection of glutamate, a purely nociceptive chemical stimulus showing that the mu-receptors are functional. By contrast the delta-opioid ligand [2-D-penicillamine, 5-D-penicillamine]enkephalin (DPDPE) had no effect on these behaviors. These findings indicate a wider function for opioid receptors in naive animals than previously envisioned.

Animals↗
PubMed1997

Effects of reverse transcriptase inhibitor therapy on the HIV-1 viral burden in semen.

HIV-1 infection continues to spread worldwide, primarily through sexual intercourse. Because semen is a major vehicle for transmission of HIV-1, we evaluated the effects of reverse transcriptase inhibitor therapy on the amount of HIV-1 in semen. The semen and blood of 11 HIV-1-infected men (i.e. treatment group) were collected before the initiation of reverse transcriptase inhibitor therapy and then 8 to 18 weeks after initiation of therapy. The semen and blood of another 11 HIV-1-infected men (i.e., longitudinal group), who were not on or had no change in antiretroviral therapy for at least 2 months before study entry, were collected at approximately 2-week intervals for 10 to 26 weeks. In the treatment group, 82% of the seminal plasma HIV-1 RNA levels decreased from baseline after 8 to 18 weeks of therapy (median reduction of 1.01 log10, p = 0.01), and 100% of the blood plasma RNA levels decreased from baseline over the same period (median reduction of 0.92 log10, p = 0.003). Five of these patients were followed for at least 52 weeks and had a median seminal plasma HIV-1 RNA level of 0.66 log10 below baseline at 1 year. All subjects in the treatment group with positive cultures at baseline (50%) had negative cultures or a lower infectious units per ejaculate at the 8- to 18-week follow-up examinations. The HIV-1 RNA levels in blood and semen of the longitudinal group did not change significantly over 10 to 26 weeks. Initiation of reverse transcriptase inhibitor therapy effectively reduces shedding of HIV-1 in semen and may therefore reduce the spread of infection within populations.

Acquired Immunodeficiency Syndrome↗