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Biomedical subjects

S Chen

Publications and source records attributed to S Chen.

At least 595 records · Page 33Linked to original sources
PubMed1999

Experience of menopausal symptoms by Chinese and Canadian women.

OBJECTIVE: This study examines the differences in frequency and distress caused by menopausal symptoms experienced by Canadian and Chinese women. DESIGN: Cross-sectional surveys were conducted in Canada and China. SETTING: The Canadian studies were conducted in Toronto. The Chinese data were collected in Guangzhou City. PARTICIPANTS: Women, 47-62 years old, 2-7 years after a natural menopause, were recruited. METHODS: Two hundred and eighty-two Canadians were recruited for two menopause studies. Data from 297 Chinese were obtained through a household survey. From a 105-item symptom questionnaire, women indicated the frequency and distress caused by symptoms in the previous month. MAIN OUTCOME MEASURES: Frequency and mean distress score of problems were ranked and compared. Using the importance score method, a Chinese questionnaire was constructed and compared with the Menopause-Specific Quality of Life questionnaire. RESULTS: The frequency of symptoms and distress experienced by Canadian and Chinese women differed markedly. Fourteen of the 29 items differed between the Chinese questionnaire and the Menopause-Specific Quality of Life questionnaire. CONCLUSIONS: There are striking differences between Chinese and Canadian women in the frequency and distress caused by menopausal symptoms. The Canadian questionnaire may not be relevant for Chinese women.

Affect↗
PubMed1999

Anti-tumor effects of PC-SPES, an herbal formulation in prostate cancer.

Prostate cancer is the most common cancer amongst males in developed countries. Surgical removal of the prostate effectively cures the primary disease but the metastatic disease is refractory to most forms of chemotherapy. There is a clinical need to develop novel treatment strategies that exploit the mode of action of both conventional and alternative drugs/medicinal plants. We have been investigating the anti-proliferative and anti-tumor effects of an herbal preparation termed PC-SPES (patent pending, US serial number 08/697, 920) which is a refined powder of eight different medicinal plants. PC-SPES administered as a food supplement caused a dramatic decrease in prostate specific antigen levels in some prostate cancer patients with advanced disease. These preliminary clinical findings laid the foundation for a program to examine the in vitro and in vivo effects of PC-SPES, and identify the active component in this mixture so that a standardized treatment regimen can be formulated. In this communication, we report the anti-tumor effects of PC-SPES incorporated in the diet utilizing a well studied Dunning R3327 rat prostate cancer model. Dietary PC-SPES at levels of 0.05% and 0.025% did not exhibit any toxicity and no significant difference in food intake was noted at the end of six weeks. Dose dependent inhibitory effect of dietary PC-SPES was observed on both tumor incidence (P=0. 01) and rate of tumor growth when tumors were induced in syngeneic Copenhagen rats by intradermal injections of MAT-LyLu cells that are known to metastasize in the lung and lymph nodes. The number of pulmonary metastases in animals on PC-SPES that showed no primary tumor growth had no metastatic lesions in the lung, however, in animals that did not respond to PC-SPES, the number of pulmonary metastases was not significantly different from the non-treated controls. The significant anti-tumor effects of PC-SPES on MAT-LyLu induced tumorigenesis and metastasis in Copenhagen rats, in general refractory to most conventional therapy, suggests a therapeutic benefit of this herbal food supplement and may be a useful adjuvant to conventional therapeutic modalities.

Animals↗
PubMed1999

NCAM stimulates the Ras-MAPK pathway and CREB phosphorylation in neuronal cells.

The neural cell adhesion molecule NCAM plays an important role in axonal growth, learning, and memory. A signaling pathway has been elucidated in which clustering of the NCAM140 isoform in the neural plasma membrane stimulated the activating phosphorylation of mitogen-activated protein kinases (MAPKs) and the transcription factor cyclic AMP response-element binding protein (CREB). NCAM clustering transiently induced dual phosphorylation (activation) of the MAPKs ERK1 and ERK2 (extracellular signal-regulated kinases) by a pathway regulated by the focal adhesion kinase p125fak, p59fyn, Ras, and MAPK kinase. CREB phosphorylation at serine 133 induced by NCAM was dependent in part on an intact MAPK pathway. c-Jun N-terminal kinase, which is associated with apoptosis and cellular stress, was not activated by NCAM. Inhibition of the MAPK pathway in rat cerebellar neuron cultures selectively reduced NCAM-stimulated neurite outgrowth. These results define an NCAM signal transduction mechanism with the potential for modulating the expression of genes needed for axonal growth, survival, and synaptic plasticity.

Animals↗
PubMed1999

Kinetics of thermal inactivation of penaeus penicillatus acid phosphatase

The kinetics of thermal inactivation of Penaeus penicillatus acid phosphatase have been studied using a kinetic method related to the substrate reaction during irreversible inhibition of the enzyme activity as previously described by Tsou (Adv. Enzymol. Relat. Areas Mol. Biol. (1988) 61, 381-436). The kinetics of thermal inactivation of the enzyme show that the reaction is irreversible. The microscopic rate constants were determined for thermal inactivation of free enzyme and the enzyme--substrate complex. The results show that the presence of substrate has a significant protective effect against thermal inactivation of the enzyme.

Journal Article↗
PubMed1999

[Significance and pitfall of diffusion weighted image in super acute cerebral ischemia: investigation by questionnaire study].

We investigated the findings in diffusion weighted image (DWI) of super acute ischemia examined within 6 hours after onset by questionnaire study. The magnitude of magnetic field of MR machine, method of diffusion weighted imaging, the total number of cases, the number of cases with high signal intensity area on DWI and the number of decrease or disappearance of signal intensity were investigated. Answers were obtained from 16 institutes (64%). Totally, 232 cases of super acute ischemia examined within 6 hours after onset were imaged by DWI. High signal intensity area were detected in 189 cases (81.5%) of all, which disappeared or decreased in 10 cases (4.3%). Follow up DWI revealed a decrease in the area of high signal intensity in 5 (17.9%) of 28 cases who underwent thrombolysis by endovascular treatment. However, 6 (21.4%) or 28 cases resulted in hemorrhagic infarction. We must recognize the diffusion anisotropy, apparent diffusion coefficient, and b value in reading the DWI. In conclusion, high signal intensity area on DWI include not only irreversible infarction but also the reversible ischemia.

Acute Disease↗
PubMed1999

Antagonist-induced reversal of functional and structural measures of hippocampal benzodiazepine tolerance.

One week oral flurazepam (FZP) administration in rats results in anticonvulsant tolerance in vivo, tolerance measured in vitro in hippocampal CA1 pyramidal cells, and regulation of hippocampal gamma-aminobutyric acid(A)-receptor subunit protein expression. A single injection (4 or 20 mg/kg i.p) of the benzodiazepine antagonist flumazenil (FLM) was given 1 day after FZP treatment, and tolerance and subunit protein expression were evaluated 1 day later. In vivo tolerance was measured by a reduced ability of the alpha(1)-subunit-selective agonist zolpidem to suppress pentylenetetrazole-induced seizures. This tolerance was reversed by 20 but not 4 mg/kg FLM. In in vitro hippocampal slices, there was tolerance to the effect of zolpidem to prolong the decay of pyramidal cell miniature inhibitory postsynaptic currents, which was reversed by FLM (4 mg/kg) pretreatment. A reduction in miniature inhibitory postsynaptic current amplitude ( approximately 50%) was also restored by FLM injection. [(3)H]Zolpidem binding measured 0, 2, and 7 days after FZP treatment was significantly decreased in the hippocampus and cortex at 0 days but not thereafter. Changes in alpha(1)- and beta(3)-subunit protein expression were examined via quantitative immunohistochemical techniques. alpha(1)-Subunit protein levels were down-regulated in the CA1 stratum oriens and beta subunit levels were up-regulated in the stratum oriens and stratum radiatum of the CA3 region. Chronic FZP effects on alpha(1)- and beta(3)-subunit protein levels were also reversed by prior FLM injection. FLM's effect on both functional and structural correlates of benzodiazepine tolerance suggests that each of these measures plays an interdependent role in mediating benzodiazepine tolerance.

Animals↗
PubMed1999

[Elimination of CD28+ T cell in patients with chronic active hepatitis].

OBJECTIVE: To study the role of toxicyte T cell in active hepatitis. METHODS: We examined CD28+ T cell in patients with chronic active/remission hepatitis by flow cytometry. RESULTS: It shows that CD28+, CD8+CD28+ T cell in patients with chronic active hepatitis decreased significantly, compared with normal control or patients with liver cirrhosis and heptoma. CONCLUSION: It implies that B7-CD28 costimulation pathway contribute to the tissue injury in hepatitis.

CD28 Antigens↗
PubMed1999

Molecular genetic analysis of pyridoxine-nonresponsive homocystinuric siblings with different blood methionine levels during the neonatal period.

Two mutations in the cystathionine beta-synthase (CBS) gene were found in two Japanese siblings with pyridoxine non-responsive homocystinuria who had different methionine levels in their blood during the neonatal period. Both patients were compound heterozygotes of two mutant alleles: one had an A-to-G transition at nucleotide 194 (A194 G) that caused a histidine-to-arginine substitution at position 65 of the protein (H65R), while the other had a G-to-A transition at nucleotide 346 (G346A) which resulted in a glycine-to-arginine substitution at position 116 of the protein (G116R). The two mutant proteins were separately expressed in Escherichia coli, and they completely lacked catalytic activity. Despite their identical genotypes and almost equal protein intake, these siblings showed different levels of blood methionine during the neonatal period, suggesting that the level of methionine in blood is determined not only by the defect in the CBS gene and protein intake, but also by the activity of other enzymes involved in methionine and homocysteine metabolism, especially during the neonatal period. Therefore, high-risk newborns who have siblings with homocystinuria, even if the level of methionine in their blood is normal in a neonatal mass screening, should be followed up and diagnosed by an assay of enzyme activity or a gene analysis so that treatment can be begun as soon as possible to prevent the development of clinical symptoms. In addition, a new, more sensitive method for the mass screening of CBS deficiency in neonates should be developed.

Adolescent↗
PubMed1999

[Analysis of MS31A in Chinese using MVR-PCR].

Allele-specific MVR-PCR can be performed on genomic DNA to sample the diversity of allelic structure at MS31A (D7S21 locus). Three polymorphic positions in MS31A 5' flanking DNA were typed from 100 unrelated Chinese in this study. The results showed that single alleles could be mapped from genomic DNA in above 80% samples of Chinese in this locus. The distribution of haplotypes of unrelated Chinese was also reported in this paper.

Alleles↗
PubMed1999

Expression, purification, and bone-inducing activity of recombinant human bone morphogenetic protein-3 mature peptide.

It was inferred that the mature peptide of human bone morphogenetic protein-3 (hBMP-3m) consists of the carboxyl terminal 127 amino acid residues of hBMP-3. A plasmid, pDH-B3m, was constructed by inserting the cDNA sequences encoding hBMP-3m into pDH, a PL-containing expression vector. pDH-B3m was transformed into Escherichia coli DH5 alpha. The highest expression level of recombinant hBMP-3m (rhBMP-3m) could be reached after 6 hours of induction at 42 degrees C, accounting for 28% of the total bacterial proteins. The rhBMP-3m was found in the inclusion bodies. After being washed and partially purified, the inclusion bodies were solubilized in urea and purified efficiently through ion-exchange chromatography. The purity of the rhBMP-3m was at least 95%. The rhBMP-3m was refolded by dilution method and then 1 mg was implanted into mouse thigh muscle to assay its activity. A classic pattern of cartilaginous osteogenesis was observed. The results showed that the purified and refolded rhBMP-3m had ectopic bone-inducing activity.

Animals↗
PubMed1999

[Tubal catheterization for transvaginal gamete intrafallopian transfer: an alternative technique for non-tubal infertility].

OBJECTIVE: To evaluate the outcome of transvaginal gamete intrafallopian transfer (TV-GIFT) for infertile patients with non-tubal factors. METHODS: Controlled ovarian hyperstimulation was used for all patients. Transvaginal ultrasound-guided oocyte retrieval followed by tubal catheterization for transvaginal gamete intrafallopian transfer of 3.3 +/- 2.1 oocytes (range 1-8) and 200,000 sperms in 50 microliters culture medium. RESULTS: The TV-GIFT was used in total of 23 treatment cycles. Of 23 cycles performed for TV-GIFT, the procedure was completed easily in 18 and difficult in 5, resulting in 5 clinical pregnancies(21.7% per cycle), 2 of which resulted in abortion, 2 ongoing pregnancy one was ectopic pregnancy. No pregnancy occurred in four cycles with only one oocyte transferred. CONCLUSIONS: Simple and cost-effective TV-GIFT may achieve a higher pregnancy rate. Compared with laparoscopically directed GIFT, tubal catheterization for TV-GIFT is safe and less invasive. It is an alternative for non-tubal infertility before entering the IVF-ET program.

Adult↗
PubMed1999

[Application of gonadotropin-releasing hormone agonist for triggering ovulation in high risk gonadotropin stimulating cycles of infertile polycystic ovary syndrome patients].

OBJECTIVE: To evaluate the efficacy and safety of gonadotropin-releasing hormone agonist (GnRH-a) instead of hCG for triggering ovulation in high risk gonadotropin stimulating cycles of infertile polycystic ovary syndrome (PCOS) patients. METHODS: GnRH-a was given for triggering follicular final maturation and ovulation in 18 gonadotropin stimulating cycles of 14 PCOS patients with mean serum estradiol (E2) level of 8,379 +/- 2,958 pmol/L. Their outcomes and complications were analysed. RESULTS: Ovulation achieved in 15 (83.3%) treated cycles, 4 (22.2%) became pregnant. Only 1 developed moderate ovarian hyperstimulation syndrome (OHSS) and another 1 had multiple pregnancy. CONCLUSIONS: The use of GnRH-a instead of hCG in high risk gonadotropin stimulating cycles is able to successfully induce ovulation and pregnancy and decrease the incidence of severe OHSS and multiple gestation.

Adult↗
PubMed1999

[Apoptosis of cultured human trophoblasts induced by tumor necrosis factor-alpha and interferon-gamma].

OBJECTIVE: To investigate the potential role of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in inducing apoptosis of human trophoblast during early pregnancy and its mechanism. METHODS: Human trophoblast of early gestation were cultured in vitro. Having cultured with TNF-alpha and IFN-gamma for 36 hours, their cytotoxic activity was determined by viable cell calculation. Apoptotic morphology was observed under light and electronic microscope. DNA fragment pattern and apoptotic index were analysed by agarose gel electrophoresis and flow cytometer assay (FCM) respectively. Adherent cell analysis and sorting interactive laser cytometer was used to examine the changes of cellular reactive oxygen species (ROS) caused by TNF-alpha. RESULTS: TNF-alpha alone significantly decreased the number of viable cells at the concentration of 1,000, 3,000 and 5,000 U/ml (P < 0.05). While combined with IFN-gamma, TNF-alpha decreased the number of viable cells more markedly. Electronic microscopic examination showed chromatin aggregating beneath the nuclear envelope, nuclear contraction and apoptotic bodies. Agarose gel electrophoresis of fragmented DNA showed a ladder-like pattern. FCM showed that the apoptotic index of trophoblasts was TNF-alpha concentration dependent. Cellular ROS was increased by TNF-alpha. CONCLUSION: TNF-alpha and IFN-gamma could induce apoptosis of human trophoblasts during early pregnancy, partly through the mechanism of ROS.

Apoptosis↗
PubMed1999

Effect of intracarotid administration of adenosine on the activity of area postrema neurons in barodenervated rats.

To observe the effect of intracarotid administration of adenosine on the electrical activity of area postrema (AP) neurons, 76 spontaneous active units were recorded from 45 sino-aortic denervated Sprague-Dawley rats using extracellular recording technique. The results obtained are as follows. (1) Following intracarotid administration of adenosine (Ado, 25 micrograms/kg), the discharge rate of 29 out of 42 units decreased markedly from 6.26 +/- 0.75 to 4.74 +/- 0.76 spikes/s (P < 0.01), whereas that of 6 units increased from 4.13 +/- 0.77 to 4.72 +/- 0.83 spikes/s (P < 0.05), and the other 7 showed no response. Blood pressure (BP) and heart rate (HR) were unaltered throughout the experiment. (2) 8-phenyltheophylline (8-PT, 15 micrograms/kg), a nonselective adenosine receptor antagonist, completely blocked the inhibitory effect of Ado in 10 units. (3) Selective A1 adenosine receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 50 micrograms/kg), blocked the effect of Ado in 12 units to a remarkable extent. (4) Glibenclamide (500 micrograms/kg), a blocker of ATP-sensitive potassium channel, abolished the effect of Ado in 12 units. The above results indicate that Ado can inhibit spontaneous electrical activity of AP neurons, which is mediated by adenosine A1-receptor with the involvement of ATP-sensitive potassium channels.

Adenosine↗
PubMed1999

[Expression of c-fos in the medulla oblongata after carotid baroreceptor activation by elevated intrasinus pressure and adenosine].

Expression of c-fos protein in the medulla oblongata after baroreceptor activation by elevated intrasinus pressure (ISP) and perfusion of adenosine (Ado) was examined in 14 vascularly isolated carotid sinus perfusion rats. The results showed that Fos-like immunoreactive (FLI) neurons were distributed throughout nucleus tractus solitarius, area postrema, rostral ventrolateral medulla and nucleus raphe pallidus, and the number of FLI was increased with the elevation of ISP. Furthermore, perfusing the carotid sinus with Ado at a given ISP markedly increased the FLI in the above regions. From the results obtained, it is concluded that the c-fos expression in baroreflex pathway in medulla oblongata may be enhanced by elevated ISP and intrasinus perfusion of Ado, and Ado is capable of facilitating the baroreflex.

Adenosine↗
PubMed1999

Biochemical changes of plasma in paratroops after parachuting: a preliminary investigation.

OBJECTIVE: To study whether physiological and psychological stresses during parachuting jumps may result in biochemical changes of plasma in parachutists. METHOD: Differences in the levels of hormones (cortisol, growth hormone, insulin, pancreatic glucagon, endothelin, angiotonin I and II, aldosterone), activities of enzymes (superoxide dismutase, glutathione peroxidase, glutathione S transferase), levels of the free radical damage indicator malondialdehyde (MDA), tumor necrosis factor alpha (TNF-alpha), and the main heat stress protein, HSP70, in the plasma and serum were investigated in control (non-parachuting) and parachuting paratroops. RESULT: Significantly higher levels of serum hormones such as growth hormone, insulin, angiotonin 1, renin activities, as well as MDA and plasma TNF-alpha and HSP70 were observed in the parachuting group. CONCLUSION: Whether these changes can potentially serve as useful biomarkers to assess possible abnormal stress in parachutists and to evaluate the health condition and to select parachutists remains to be further studied.

Adolescent↗
PubMed1999

Cloning and expression of beta 2-glycoprotein 1 recognized by antiphospholipid antibodies and its clinical investigation.

OBJECTIVE: To investigate cloning and expression of beta 2-glycoprotein 1 (beta 2GP1) recognized by antiphospholipid antibodies and to study the clinical significance of anti-beta 2GP1 antibodies in patients with autoimmune disease. METHODS: By using reverse transcription-PCR method, two kinds of expression plasmid which expressed beta 2GP1 and the fifth domain of beta 2-glycoprotein 1 (beta 2GP1-D5) proteins respectively were constructed in this study. Their antigenic activities were identified by immunoblots using rabbit anti-beta 2GP1 antibodies. Anti-r beta 2GP1 and anti-r beta 2GP1-D5 antibodies in the 112 patents were detected by ELISA using r beta 2GP1 and r beta 2GP1-D5 as coating antigens. RESULTS: A significant correlation in statistics (r = 0.667, P < 0.01) between the levels of anti-r beta 2GP1 and anticardiolipin antibodies (aCL) was found. The presence of anti-r beta 2GP1 antibodies was associated with an increased frequency of history of thrombosis and/or recurrent abortion. Anti-r beta 2GP1 assay provided better specificity than conventional aCL assay. The binding of anti-r beta 2GP1 from the sera of patients with antiphospholipid syndrome (APS) to r beta 2GP1 was inhibited by r beta 2GP1-D5. Meanwhile, of 28 patients who had positive anti-r beta 2GP1 antibodies in sera, 27 (96.4%) had positive anti-r beta 2GP1-D5 antibodies. CONCLUSION: It is indicated that antigenic epitope of beta 2 GP1 might be located in its fifth domain. Detection of anti-r beta 2GP1 antibodies may be of potential value for evaluating the risk of thrombosis and/or other APS associated symptom.

Antibodies, Antiphospholipid↗