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Biomedical subjects

D Wang

Publications and source records attributed to D Wang.

At least 811 records · Page 45Linked to original sources
PubMed1996

The chemical modification of E. coli L-asparaginase by N,O-carboxymethyl chitosan.

E. coli L-asparaginase was modified with N,O-carboxymethyl chitosan in the presence of normal product L-aspartic acid, which protected the active site of the enzyme. The modified enzyme remained high catalytic activity, showed greater stability against trypsin and alpha-chymotrypsin, but lost its activity more rapidly at high temperature (> 45 degrees C) than did the native enzyme. When tested in vivo, the plasma half-life of the modified enzyme (t1/2 = 40 hr) was over 33 times longer than that of the native enzyme (t1/2 = 1.6 hr). The results showed that the modified L-asparaginase may be much more useful than did the native enzyme for clinical treatments of tumors.

Animals↗
PubMed1996

[Human reliability in manned spaceflight].

Human error may threaten the security in manned spaceflight, this paper discusses the importance of the role played by man and human reliability in spaceflight safety, and analyses the reduction of human reliability by errors. The causes of the errors are also analysed in respect to reduction of risk of astronaut selection, strengthening of training, provision of medical monitoring and supplies, as well as prevention of errors from management factors. Measures to raise human reliability are proposed

Accidents, Aviation↗
PubMed1996

Risperidone augmentation of SRI treatment for refractory obsessive-compulsive disorder.

BACKGROUND: Although serotonin reuptake inhibitors (SRIs) are the mainstay of pharmacologic treatment for obsessive-compulsive disorder (OCD), many patients do not have an adequate response to these medications. One approach to treating SRI-refractory OCD patients has been to add other classes of medications to the SRI. We predicted that augmentation with risperidone would alleviate symptoms in SRI-refractory OCD patients. METHOD: 21 patients were treated openly with the combination of an SRI and adjunctive risperidone (mean dose = 2.75 mg/day). All met DSM-IV criteria for obsessive-compulsive disorder and had a variety of comorbid disorders. Prior to addition of risperidone, all patients had failed to respond to at least one adequate trial of an SRI. Response was determined by clinical judgment and standardized rating scales. RESULTS: 5 (24%) of the 21 patients experienced side effects (most commonly, akathisia), which forced discontinuation of risperidone. Of the 16 patients who tolerated combined treatment, 14 (87%) had substantial reductions in obsessive-compulsive symptoms within 3 weeks. Patients with horrific mental imagery had the strongest and fastest response, often within a few days. Patients with comorbid psychotic disorders improved gradually over 2 to 3 weeks. Patients with comorbid tic disorders had the poorest rate of response and highest rate of akathisia. CONCLUSION: These results suggest that risperidone augmentation is effective and well tolerated in patients with SRI-refractory obsessive-compulsive disorder. Response to risperidone augmentation appears to be influenced by symptom subtypes and comorbid conditions. Controlled trials are required to confirm the efficacy of risperidone augmentation for refractory OCD.

Adult↗
PubMed1996

The activity of recent anti-allergic drugs in the treatment of seasonal allergic rhinitis.

Two experiments were performed during the pollen season to study the activity of different antiallergic drugs in the treatment of seasonal allergic rhinitis. Nasal allergen challenge (NAC) was performed to mimic an acute attack of allergic rhinitis and to objectively evaluate the effect of the drugs on the early-phase reaction during the season. The first study assessed the effect of H1 (Cetirizine 10 mg a day) and of a combination of H1 (Cetirizine 10 mg) plus H2 (Cimetidine 800 mg a day) antagonists on nasal symptoms, mediator release and eosinophil count in a group of 16 patients with seasonal allergic rhinitis. During the same season a second study compared in a randomized way (2 parallel groups) the effect of Budesonide (Rhinocort Aqua) and Azelastine (Allergodil nasal spray) in a group of 14 patients. Results showed that both antihistamines, applied topically of dosed orally, reduced sneezing even when significant increases of histamine concentration in nasal secretions were evidenced immediately after NAC. When a combination of Cetirizine and Cimetidine was administered, a significant (p < 0.01) reduction of nasal airway resistance and increase of nasal airflow after NAC were demonstrated as well. In addition, topical application of Budesonide showed a strong (p < 0.01) effect on the infiltration and activation of eosinophils during the season, and on tryptase release after NAC. These effects lasted at least for one week after therapy.

Adult↗
PubMed1996

The determinants of the duration of contraceptive use in China: a multilevel multinomial discrete-hazards modeling approach.

Often in demography, individuals may change state over time for a variety of reasons. Competing-risks hazards models have been developed to model such situations. This paper describes the extension of the discrete-time competing-risks hazards model to a multilevel framework that allows for data at different levels of aggregation. The model is illustrated with data from the 1988 Chinese National Survey of Fertility and Contraceptive Prevalence, which collected complete contraceptive histories. Women may stop using a method of contraception for a number of reasons; this paper describes how one can control for correlations between the outcomes of repeated spells of contraceptive use.

Adolescent↗
PubMed1996

[Cloning and sequencing of VH and VL genes of an anti-human lung adenocarcinoma monoclonal antibody].

By comparing the conserved regions at each end of the nucleotide sequences of murine germ-line genes encoding FR1 and FR4 regions of immunoglobulin heavy and light chain variable regions, we designed two sets of primer for amplification of VH and VL genes. Hybridoma cell WLA-2C4, secreting an antihuman lung adenocarcinoma McAb, was cultured and the genome DNA was extracted and used as template for PCR. After PCR the desired VH and VL fragments were amplified. The PCR products were then cloned into pUC19 vector. By screening and identification, several recombinants that had been inserted with the target fragments were obtained. Then they were sequenced with Sanger's method. It was confirmed by computer-assisted comparative sequence analysis that clones of full-length and potentially functional VH and VL genes from the hybridoma cell line WLA-2C4 were ob-tained.

Adenocarcinoma↗
PubMed1996

[Effects of stress on indices for assessing zinc nutrition status].

To evaluate the specificity of some functional indices in assessment of body zinc nutrition status, we used experimental rat model to observe the effects of some factors, such as forced swimming, starvation, trauma and alcohol intoxication on zinc the status. Plasma zinc levels of rats significantly decreased after trauma increased after starvation. Liver zinc content showed a rising tendency in trauma and starvation rats. Activities of superoxide dismutase in red blood cells and alkaline phosphatase, mannosidase, 5'-nucleotidase in plasma of rats with alcohol intoxication declined significantly. Starvation led to decreased activities of alkaline phosphatase and angiotensin-converting enzyme, but increased activities of mannosidase. Trauma and forced swimming could cause increase of angiotensin-converting enzyme activity and decrease of 5'-nucleotidase activity, respectively. These results indicate that physiological and pathological effects should be excluded from of the above indices as plasma zinc index, in the assessment of body zinc nutrition status.

Alkaline Phosphatase↗
PubMed1996

Effect of nucleotides 37 and 38 on cleavage of tRNAPhe precursors.

Splicing is required for tRNA maturation when the precursors contain the introns. In order to determine whether nucleotides 37 and 38 affect splicing, yeast tRNAPhe precursors with different nucleotides 37 and 38 were prepared by in vitro mutagenesis and cleaved by the purified yeast tRNA-splicing endonuclease. The precursors with purine nucleotides at N37 and N38 were found to be the best substrates for the enzyme. When N37 and N38 were replaced by pyrimidine nucleotides, few precursors could be cleaved by the endonuclease. If one is pyrimidine nucleotide, the other one is purine nucleotide at these positions, the cleavage efficiencies are between the two groups of precursors stated above. The pyrimidine nucleotides at these positions might affect the fine structures of the precursors or the distance between the splicing sites, so that the precursors can not be fixed or anchored on the enzyme well, leading to the poor cutting.

Mutagenesis, Site-Directed↗
PubMed1996

[Clinical and experimental studies of yuyang powder in treatment of peptic ulcer].

Two hundreds patients of peptic ulcer diagnosed by fiber-gastroscope treated with Yuyang powder (YYP) was observed and compared with patient treated with cimetidine for control. Results showed that the curative rate of YYP on peptic ulcer was 88.1%, the total effective rate was 96%, similar to that of cimetidine. But the difference of recurrence rate (19.1% for YYP and 46% for control) between the two groups was very significant. Animal experiment revealed that the protective action of YYP with high dosis on gastric mucosa in peptic ulcer and gastritis was superior to that of cimetidine, its has the double effect of both strengthening protective factors and weakening aggressive factors of gastric mucosa. Acute toxicologic test indicated that YYP has no toxic effect and was safe in clinical practice.

Adolescent↗
PubMed1996

Response of the neonatal rat cardiomyocyte in culture to energy depletion: effects of cytokines, nitric oxide, and heat shock proteins.

Cytokines exert autocrine and paracrine effects on the heart, some of which may be mediated by inducible nitric oxide synthase (i-NOS) expression. We studied the effects of cytokine-mediated NO synthesis on cell injury in the presence of deoxyglucose (DOG) and cyanide (CV)(20 mM DOG and 2 mM CN) for up to 3 hours and during recovery (18 hours). The influence of heat shock protein-70 on the extent of myocyte damage was also assessed. IL-1 beta and gamma-IFN act synergistically to enhance NO synthesis by cardiac myocytes. When these cytokines are present, the rate of ATP depletion after DOG and CN is significantly greater than in their absence. When IL-1 beta and gamma-IFN are added with the NOS inhibitor, L-monomethyl-L-arginine (L-NMMA), or when a cytokine that does not produce NO (TNF-alpha) is present, the rate of ATP depletion is no different from the rate seen with DOG and CN alone. After recovery for 18 hours, myocytes that were exposed to IL-1 beta and gamma-IFN release more lactic dehydrogenase and have significantly lower levels of ATP. L-NMMA decreases lactic dehydrogenase release and maintains ATP at levels similar to metabolically inhibited cells in the absence of these cytokines. Consistent with the decreased recovery in ATP with cells incubated with DOG and CN plus IL-1 beta and gamma-IFN is a decrease in cytochrome oxidase activity. Decreases in cellular ATP correspond to increased levels of heat shock protein-70 measured in myocytes after 18 hours of recovery after metabolic inhibition in the presence of IL-1 beta and gamma-IFN. In contrast, prior induction of heat shock protein-70 reduces the rate of ATP depletion in myocytes treated with DOG and CN and maintains ATP at levels that are significantly higher than those seen in non-heat-shocked cells. Recovery of cells exposed to heat shock is also greater, as seen by decreased lactic dehydrogenase and citrate synthase release. The heat-shocked myocytes contain significantly more glycogen than the cells that were not heat shocked. The increased cellular glycogen is likely responsible for the greater lactate production and slower rates of ATP depletion in the heat-shocked, metabolically inhibited cells. Cell survival under conditions of metabolic inhibition is closely related to cellular ATP preservation.

Adenosine Triphosphate↗
PubMed1996

Studies on high-density cultivation of Vero cells with biosilon solid microcarrier.

From eight kinds of microcarriers, Biosilon has been chosen as the most suitable microcarrier for high-density cultivation of African green monkey kidney (Vero) cells. Conditions affecting high-density cultivation were studied with a 500 ml modified Wheaton spinner flask. When cultivation with a 1.5 L CelliGen bioreactor at inoculum density of 4.9 x 10(6)/ml and perfusion volume increased from 0.20 L to 3.65 L gradually, the cell density could reach 2.05 x 10(7)/ml after 22 days of cultivation. When Vesicular Stomatitis Virus (VSV) was inoculated into the cultures of 1.21 x 10(6) ml at the some MOI (multiplicity of infection), the virus titers reached 7 log TCID50/ml and 8 log TCID50/ml, respectively.

Animals↗
PubMed1996

[Experimental study on delayed effect of external skin expansion].

In using the external skin expander, we found that the expanded skin had the feature similar to a delayed flap. To study its mechanism, we chose 20 New Zealand rabbits and divided them into 2 groups randomly. The skin on the animal's back in the experimental group was expanded with the external skin expander. The laser Doppler flowmeter (LDF) and oxyhemograph (SpO2) were applied to detect skin microcirculation. The survival area and the results of microangiography of the two groups were compared. Results showed that the value of LDF of the expanded skin increased and the value of SpO2 returned to its origingal level at 12 days after expansion. The survival area in the experimental group was larger than the control. Microangiographic examinations indicated that the subcutaneous vascular anastomoses were obviously increased in the experimental group. We conclude that external skin expansion does not affect the quality of the expanded skin, and its effect is similar to delay technique.

Animals↗
PubMed1996

[Effect of IL-4 on biological regulation of tumor cell lines].

The effect of IL-4 on biological regulation of tumor cell lines was observed by using human recombinant interleukin-4. The observation included cell proliferation, differentiation, cell surface marker and cytokine secretion. The effect of IL-4 on cell proliferation of nine cell lines was different. It showed 4/9 inhibitory effect, 3/9 enhancing effect and 2/9 no effect. The inhibitory effect of IL-4 on U937 cell proliferation was correlated with cell differentiation. IL-4 enhanced the expression of cell surface markers (including MHC class I, MHC class II and TAA) of some cell lines. Furthermore, IL-4 inhibited the production of IL-2 by MLA144. The preliminary results indicate that the effect of IL-4 on biological regulation of tumor cell lines is benefitial for controlling tumor cell growth and enhancing tumor cell recognition by effector cells. However, the down regulation also could be exerted.

Animals↗
PubMed1996

[Monoclonal antibodies to human progesterone receptors: production, indentification and clinical application].

A peptide with 15 amino acid of human progesterone receptor (PR) was synthesized and used as antigen. Five hybridoma cells were obtained by cloning technique. In tests to hybridoma cell H4, the site specificity of the antibody to PR was found. The antibody reacted specifically with PR, but did not cross-react with ER, AR, or GR. Five women who used clomiphene citrate (CC) 100mg/d x 5 days were involved in a study of serum pregesterone (P) and endometrial histology in early luteal phase. There was no difference in serum P level in two groups. Three cases in CC group showed abnormal secretory endometrium. PR concentration in the nuclei of glandular cells of endometrium in CC group was significantly lower than that in the control group. In women with abnormal secretory endometrium, PR concentration in the nuclei of glandular cells was lower than that in women with normal endometrial histology. CC can influence endometrial histology by changing-PR concentration in the nuclei of glandular cells. The endometrium can not respond to the stimulus of P at normal levels and thus results in luteal phase defect.

Animals↗
PubMed1996

[A study of loss of heterozygosity and mRNA expression at DCC locus in gastric cancers].

To evaluate the role of DCC gene alteration in the development and progression of gastric cancer, loss of heterozygosity (LOH) and mRNA expression of DCC gene was examined in surgically resected gastric cancer specimens using PCR-RFLP and RT-PCR analyses. LOH was detected in 18 (35.3%) of 51 informative cancers specimens. The frequency of LOH in stages III and IV (50.0%) was significantly higher than that in stages I and II (14.3%, P < 0.05%), but LOH was not correlated to histological types, tumor size, invasion depth and lymph node metastases. Expression of DCC mRNA in 26/51 cases was examined and the DCC expression was lost in 8/26 (30.7%) cancer, and no significant correlation was found between loss of DCC expression or LOH and clinico-pathologic parameters. LOH and loss of expression at DCC gene occur frequently in gastric cancers, LOH at DCC locus is a late event.

Gene Deletion↗
PubMed1996

[The new concept of the cutaneous vascular framework in the leg].

An anatomical study was carried out using 15 legs of fresh cadavers. According to skin angiography, the authors set up a new concept of the vascular structure of skin and skin flap. The characteristics of the blood supply to the skin were revealed and analyzed. The first vascular frame unit, the second vascular frame unit and the superficial fascial network were described. The willow-shaped descending vascular branches were found and discussed, and they constituted a special blood supply in subcutaneous tissue.

Adult↗
PubMed1996

[Asphyxia of the newborn delivered by elective cesarean section and gastroesophageal reflex and aspiration].

OBJECTIVE: To analyse the causes, clinical manifestation, management and prevention of gastroesophageal reflex and aspiration (GER-A) in the infants delivered by cesarean section. METHOD: The clinical data of 6 infants with asphyxia resulted from GER-A, delivered by elective cesarean section were retrospectively analysed. RESULTS: GER-A occurred during the period from 5 to 12 minute after birth, and its main clinical manifestation was airway obstruction. Among the patients, four cases recovered completely after treatment, one was diagnosed as having aspiration pneumonia and the other died of severe bronchospasm. CONCLUSIONS: The occurrence of this complication was probably related to the mode of delivery by cesarean section, the underdevelopment of effective barrier for preventing GER-A at very early stage and the inadequate management of the newborn. It is suggested that the prevention and proper treatment of GER-A was important in lowering neonatal morbidity and mortality.

Asphyxia Neonatorum↗