Biomedical subjects

G Chen

Publications and source records attributed to G Chen.

At least 181 records · Page 10Linked to original sources

PubMed2001

[Influence of environmental factors on CH4 emission from Reed Wetland].

Determination of CH4 emission from reed wetland in Liaohe delta, China using closed chamber(enclosure area 0.64 m2) technique showed that average emission rate of CH4 was 520 micrograms.m-2.h-1 with significant seasonal patterns. When soil redox potential reached -110 mV, CH4 occured and increased with its decrease. CH4 emission was also influenced by water management and reduced with deep water cover. During the period of measurement, there was positive relation between temperature and CH4 flux(R2 = 0.196, n = 21, P < 0.05). In addition, the experimental result also showed that the methanogenic activites in 0-5 cm soil layer were higher and decreased obviously with soil deepening.

Methane↗

PubMed2001

Bipolar disorder: leads from the molecular and cellular mechanisms of action of mood stabilisers.

Background New research is dramatically altering our understanding of the molecular mechanisms underlying neuronal communication. Aim To elucidate the molecular mechanisms underlying the therapeutic effects of mood stabilisers. Method Results from integrated clinical and laboratory studies are reviewed. Results Chronic administration of lithium and valproate produced a striking reduction in protein kinase C (PKC) isozymes in rat frontal cortex and hippocampus. In a small study, tamoxifen (also a PKC inhibitor) had marked antimanic efficacy. Both lithium and valproate regulate the DNA binding activity of the activator protein 1 family of transcription factors. Using mRNA differential display, it was also shown that chronic administration of lithium and valproate modulates expression of several genes. An exciting finding is that of a robust elevation in the levels of the cytoprotective protein, bcl-2. Conclusions The results suggest that regulation of signalling pathways may play a major part in the long-term actions of mood stabilisers. Additionally, mood stabilisers may exert underappreciated neuroprotective effects.

Journal Article↗

PubMed2001

[Intron 44 is not the most unstable intron in the "central deletion hot spot" of dystrophin gene].

OBJECTIVE: To understand the distributional characteristics of dystrophin gene deletion breakpoints in "central deletion hot spot" and analyze the instability of introns 44-51 after excluding the effect of intron's length. METHODS: Fifty-nine Duchenne/Becker muscular dystrophy(DMD/BMD) patients were detected by polymerase chain reactions with the primers to amplify exons 44-52 of dystrophin gene. The amount of actual breakpoints, expected breakpoints according to its length, and the ratios of actual breakpoints to expected values(A/E) for introns 44-51 were calculated respectively. RESULTS: In "central deletion hot spot", about 30.8% of breakpoints fell in intron 44, about 23.1%, 17.9%, 10.3%, 10.3% of breakpoints fell in introns 50,51, 45, 48, respectively. But the amount of actual breakpoints of intron 44 was less than that of expected breakpoints according to its length, the ratio of A/E was 0.7. The amount of actual breakpoints of introns 48, 50, 51, 45 were more than that of length expected value. The ratios of A/E were 2.7, 2.0, 1.9, 1.1, respectively. CONCLUSION: Intron 44 is more stable than the whole molecular region of "central deletion hot spot". Introns 48, 50 and 51 are comparatively instable in "central deletion hot spot".

Dystrophin↗

PubMed2001

Approval summary: gemtuzumab ozogamicin in relapsed acute myeloid leukemia.

PURPOSE: Gemtuzumab ozogamicin (Mylotarg; Wyeth Laboratories, Philadelphia, PA) consists of a semisynthetic derivative of calicheamicin, a cytotoxic antibiotic linked to a recombinant monoclonal antibody directed against the CD33 antigen present on leukemic myeloblasts in most patients with acute myeloid leukemia (AML). In this study, we review the preclinical and clinical profiles of this immunoconjugate and the regulatory review that led to marketing approval by the United States Food and Drug Administration. EXPERIMENTAL DESIGN: From the literature and manufacturer's data, we review the activity, tolerability, and pharmacokinetics of gemtuzumab ozogamicin in preclinical and Phase I studies and its activity, efficacy, and side effects in three Phase 2 trials of 142 patients with relapsed AML. RESULTS: In Phase I studies, the major toxicity was myelosuppression, especially neutropenia and thrombocytopenia, resulting from the expression of CD33 on myeloid progenitor cells. The Phase 2 dose was 9 mg/m(2) infused i.v. over 4 h, repeated on day 14. A minority of patients experienced acute infusion-related symptoms, usually transient and occasionally requiring hospitalization. The complete response (CR) rate with full recovery of hematopoiesis was 16%. A subset of patients [CRs with incomplete platelet recovery (CRps)] was identified with blast clearance and neutrophil recovery but incomplete platelet recovery. The duration of responses of CRps appeared to be similar to those of the CRs, although the numbers were small. The question of the equivalence of these response groups was a central issue in the review of this new drug application (NDA). After considerable discussion, the Oncology Drugs Advisory Committee recommended allowing inclusion of CRps resulting in an overall response rate in the Phase 2 studies of 30%. In the subgroup of patients over 60 years of age, the overall response rate was 26%. Response duration was difficult to establish because of the high prevalence of postremission therapies. Tolerability and ease of administration may be improved compared with conventional chemotherapy, except for hepatotoxicity, with 31% of patients exhibiting abnormal liver enzymes. One patient died of liver failure in the Phase 2 trials. CONCLUSIONS: Marketing approval of gemtuzumab ozogamicin was granted on May 17, 2000 by the United States Food and Drug Administration under the Accelerated Approval regulations. Gemtuzumab ozogamicin is indicated for the treatment of patients with CD33 positive AML in first relapse who are 60 years of age or older and who are not considered candidates for cytotoxic chemotherapy. The approved dose was 9 mg/m(2) i.v. over 4 h and repeated in 14 days. Completion of the ongoing studies of gemtuzumab ozogamicin in relapsed AML and initiation of randomized clinical trials comparing the effects of gemtuzumab ozogamicin in combination with conventional induction chemotherapy to conventional chemotherapy alone on survival are mandated to confirm clinical benefit under the accelerated approval Subpart H regulations. Postmarketing reports of fatal anaphylaxis, adult respiratory distress syndrome (ARDS), and hepatotoxicity, especially venoocclusive disease (VOD) in patients treated with gemtuzumab ozogamicin, with and without associated hematopoietic stem cell transplantation (HSCT), have required labeling revisions and the initiation of a registration surveillance program. Tumor lysis and ARDS have been reported in patients with leukocytes above 30,000/ml treated with gemtuzumab ozogamicin; therefore, the reduction of leukocyte counts to below 30,000/ml is recommended prior to treatment. Patients should be carefully monitored for acute hypersensitivity, hypoxia, and delayed hepatotoxicity following treatment with gemtuzumab ozogamicin.

Adolescent↗

PubMed2001

[Expression of inhibin alpha and inhibin/activin beta A subunits in the developing follicles of the duck].

The very sensitive quantitative competitive reverse transcription-polymerase chain reaction (RT-PCR) was used to investigate the expression of mRNA for the inhibin alpha and inhibin/activin beta A subunit in the developing ovarian follicles of the duck. The results indicated all follicles showed the expression of mRNA for the inhibin alpha and inhibin/activin beta A. The inhibin alpha subunit mRNA is expressed more abundantly than the beta A subunit in the large preovulatory follicles. Competitive RT-PCR revealed that the expression of inhibin alpha subunit is the highest in small yellow follicles (SYF), the mean relative content for the F1, F2, F3, F4/5 and LWF (large white follicle) was 0.26 +/- 0.05, 0.28 +/- 0.07, 0.57 +/- 0.12, 0.98 +/- 0.09 and 0.026 +/- 0.006, respectively, compared to a mean relative content of 1.00 for the SYF. The highest level of inhibin/activin beta A mRNA was found in the F1 follicle, the mean relative content for the F2, F3, F4/5, SYF and LWF was 0.218 +/- 0.09, 0.111 +/- 0.03, 0.058 +/- 0.011, 0.053 +/- 0.013 and 0.005 +/- 0.002, respectively, compared to a mean relative content of 1.00 for the F1 follicle. Our data suggest that the expression of the alpha subunit is reduced with follicular development whereas beta A subunit expression is dramatically enhanced, which indicates the expression of inhibin alpha and inhibin/activin beta A subunit is differentially regulated during follicular development. In addition, the highest level of beta A mRNA in F1 follicle indicates the production of dimeric inhibin and/or activin primarily occurred in the largest F1 follicle.

Animals↗

PubMed2001

Bipolar disorder: leads from the molecular and cellular mechanisms of action of mood stabilizers.

BACKGROUND: New research is dramatically altering our understanding of the molecular mechanisms underlying neuronal communication. AIM: To elucidate the molecular mechanisms underlying the therapeutic effects of mood stabilizers. METHOD: Results from integrated clinical and laboratory studies are reviewed. RESULTS: Chronic administration of lithium and valproate produced a striking reduction in protein kinase C (PKC) isozymes in rat frontal cortex and hippocampus. In a small study, tamoxifen (also a PKC inhibitor) had marked antimanic efficacy. Both lithium and valproate regulate the DNA binding activity of the activator protein I family of transcription factors. Using mRNA differential display, it was also shown that chronic administration of lithium and valproate modulates expression of several genes. An exciting finding is that of a robust elevation in the levels of the cytoprotective protein, bcl-2. CONCLUSIONS: The results suggest that regulation of signalling pathways may play a major part in the long-term actions of mood stabilizers. Additionally, mood stabilizers may exert underappreciated neuroprotective effects.

Antimanic Agents↗

PubMed2001

[Studies of genetic diversity of Zhejiang native chicken breeds].

A total of 539 bases of mitochondrial DNA D-loop region of five native chicken breeds of Zhejiang province and the white leghorn chicken (as the control) were sequenced by DNA sequencing technique, and the phylogenetic trees of the chicken breeds were constructed. The results showed that 24 variation sites i.e. 4.45% sequence divergence were detected among the 30 DNA sequences, and the six breeds belonged to two different maternal lineage, one included Xianju chicken and White Leghorn chicken which had the same maternal origin, the other included Lingkun chicken, Baiyiner chicken, Wugu chicken and Xiaoshan chicken which had the same matriarchic ancestor. Among the latter lineage, Lingkun chicken, Baiyiner chicken and Wugu chicken had a closer relationship to each other than to Xiaoshan chicken.

Animals↗

PubMed2001

[cDNA cloning and mRNA expression pattern in follicles of the mature inhibin alpha subunit from Xianju chicken].

The mature region of Xianju chicken inhibin alpha-subunit was amplified from the total RNA of follicle granulosa cells by RT-PCR using the primer pair designed according to the reported cDNA sequence of chicken inhibin alpha-subunit, and this fragment of alpha-subunit was cloned and sequenced subsequently. The results revealed that the mature alpha-subunit of Xianju chicken was a fragment of 113 amino acids containing one glycosylation site and seven cysteine residues. It was approximately 98% and 61.4%-68.7% identical in nucleotide sequence, 97.3% and 64.6%-69% similar in deduced amino acid sequence, respectively, in the mature region to the chicken and mammalian inhibin alpha-subunit cDNA clone. As for the mature chicken inhibin alpha-subunit, the number of potential glycosylation site and cysteine residues was the same, and their corresponding positions in the amino acid sequences were almost identical as compared to chicken and mammalian inhibin alpha-subunit, which indicated that the inhibin alpha-subunit was highly conserved among different species, implying an important role of inhibin alpha-subunit in various animals. The quantitative analysis of competitive RT-PCR for inhibin alpha-subunit revealed that the expression of alpha-subunit decreased with further follicle maturity from SYF to F1 follicle. The highest level of inhibin alpha-subunit mRNA was found in the SYF and F6-8 follicles, which indicated that inhibin alpha-subunit played an important role during the course of follicular recruitment, selection and dominance.

Amino Acid Sequence↗

PubMed2001

[Morphological and histological studies on Aralia plants].

OBJECTIVE: To make clear the descriptions and microscopic histological structures of the roots, stems and rootstocks for twelve species from Aralia plants. METHODS: Observing the descriptions and histological characteristics. RESULT: The histological characteristics of the various species are basically identical. Each of them equally contains cluster crystals of calcium oxalate and starch grains; secretory canals exist extensively in the cortexes, phloem and piths; neither cortexes nor phloem of roots have thick-walled cells, but cortexes and phloem of the stems of the wood plants have fibers or stone cells. CONCLUSION: The pharmacognostic and interspecies characteristics for wood and herbaceous plants identification were obtained. The wood and herbaceous plants in one natural group of a genus as its two subgenera was sustained by the study result.

Aralia↗

PubMed2001

[Expression pattern of mRNA for follistatin and inhibin/activin beta B-subunit during follicular and testicular development in duck].

Follistatin and inhibin/activin were closely related glycoprotein hormones. The quantitative competitive RT-PCR was used to investigate the expression of follistatin and inhibin/activin beta B-subunit mRNA in the developing ovarian follicles, immature and mature testes. The results revealed all samples showed the expression of mRNA for the two proteins, and the expression is more abundantly in the small follicles than in the large preovulatory follicles. Competitive RT-PCR revealed that the expression of follistatin is the highest in small yellow follicles (SYF), the mean relative content for the F1, F2, F3, F4, F5, F6-8, LWF (large white follicle), TI(immature testes), and TM(mature testes) was 0.011 +/- 0.004, 0.019 +/- 0.006, 0.021 +/- 0.009, 0.028 +/- 0.007, 0.075 +/- 0.023, 0.15 +/- 0.072, 0.29 +/- 0.068, 0.037 +/- 0.011, and 0.012 +/- 0.004, respectively, compared to a mean relative content of 1.00 for the SYF. The highest level of inhibin/activin beta B mRNA was also found in the SYF, the mean relative content for the F1, F2, F3, F4, F5, F6-8, LWF, TI, and TM was 0.009 +/- 0.003, 0.013 +/- 0.005, 0.019 +/- 0.007, 0.023 +/- 0.006, 0.29 +/- 0.084, 0.84 +/- 0.093, 0.031 +/- 0.008, 0.38 +/- 0.072, and 0.046 +/- 0.013, respectively, compared to a mean relative content of 1.00 for the SYF. Our data suggested that the expression pattern of mRNA for follistatin and inhibin/activin beta B-subunit was quite similar during follicular and testicular development. The great co-expression of mRNA for the two proteins in small follicles indicated that activin B(beta B-beta B) availability was tightly regulated by follistatin, and the two proteins might both play important roles in early follicular development.

Activins↗

PubMed2001

Integration of chemical and biological treatments for textile industry wastewater: a possible zero-discharge system.

Theoretical and experimental studies have established that integrated treatment systems (mostly chemical and biological) for various industrial wastewaters can achieve better quality of treatment and can be cost-effective. In the present study, the objective is to minimize the use of process water in the textile industry by an economical recycle and reuse scheme. The textile wastewater was first characterized in terms of COD, BOD5, salinity and color. In order to recycle such wastewater, the contaminants should be mineralized and/or removed according to the reusable textile water quality standards. Typical results show that this is achievable. An economic analysis has been conducted on the proposed integrated system. The economic analysis shows that the integrated system is economically more attractive than any of the single treatment technologies for achieving the same target of treatment. The information presented in this paper provides a feasible option for the reduction of effluent discharges in the textile industry.

Conservation of Natural Resources↗

PubMed2001

[Typing of Streptococcus mutans (serotype C) by arbitrarily primed polymerase chain reaction].

OBJECTIVE: To study the relationship between genetic diversity within Streptococcus mutans (C), and dental caries. METHODS: One reference strain (GS5) was used to establish the suitability of primers and the initial AP-PCR conditions. Isolates of Streptococcus mutans (C) were obtained from 19 caries-free and 40 caries-active patients, and were originally isolated on mitis-salivarius-bacitracin agar. Totally 278 isolates were biochemically and serologically confirmed as Streptococcus mutans (C). Chromosomal DNA was extracted from those isolates by Chelex. One random primer, OPA-05 was used as a template in PCR reaction. All amplification reactions were conducted in a volume of 20 microliters containing 2 microliters of 10 x reaction buffer, 200 mumol/L each of dATP, dCTP, dGTP and dTTP and 2.5 units of Taq DNA polymerase. We varied the concentrations of MgCl2 (1.5-4.5 mmol/L), template DNA (2-40 ng), and primer (0.3-0.5 mumol/L) to determine the optical conditions for AP-PCR. The temperature profile in a thermocycler was 35 cycles as follows: 94 degrees C for 1 min, at 36 degrees C for 2 min, at 72 degrees C for 2 min. The initial denaturation was at 94 degrees C for 5 min and the final extension at 72 degrees C for 5 min. RESULTS: The MgCl2 concentration in 4 mmol/L and the primer concentration in 0.5 mumol/L produced clearly distinct and reproducible fingerprints. We found 105 different patterns among the 278 isolates. In high-caries persons more than one genotype isolates of Streptococcus mutans (C) were colonized. CONCLUSIONS: Isolates of Streptococcus mutans (C) exist apparent genetic diversity. The genotypes of isolates might relate to differences in caries susceptibility.

DNA, Bacterial↗

PubMed2001

Effect of Salvia miltiorrhiza Bunge injection on anticardiolipin antibody production induced by beta2 glycoprotein.

AIM: To explore the therapeutic effect and the mechanism of Chinese herbs on antiphospholipid syndrome (APS) by observing the effect of Salvia miltiorrhiza Bunge injectio (SmBI) on anticardiolipin antibody (aCL) induced by beta2 glycoprotein I (beta2-GP I). METHODS: Sixty female mice randomly fell into 6 groups: group A, B, C, D was injected through abdominal cavity with different dosage of SmBI daily; after 14 d, group A, B, C, E was immunized with 150 microg of purified human beta2-GP I in complete Freund's adjuvant subcutaneously; group F as control. The titre of aCL were detected by enzyme linked immunosorbent assay; subsets of T cell were grouped by streptavidin-biotin complex technique; and the activity of IL-2 was measured by MTT chromatometry. RESULTS: (1) Compared with group E, the absorbance (A) of aCL in group A, B, and C was decreased (P < 0.05 or P < 0.01). By linear correlation, the dosage is negatively correlated with the A values of aCL in 1, 2, and 3 weeks (P < 0.01). (2) Compared with group E, TH/TS ratio was reduced in group A, B, and C (P < 0.05 or P < 0.01); there is no significant differences between group D and F (P>0.05). By linear correlation, the dosage is negatively correlated with TH/TS ratio (P < 0.01). (3) Compared with E, the activity of IL-2 in group B and C decreased significantly (P < 0.01). By linear correlation, there is negative correlation between dosage and IL-2 activity (P < 0.01). There is no significant difference between D and F (P > 0.05). (4) There is positive correlation between TH/TS ratio and IL-2 activity in different dilutions (P<0.01). CONCLUSION: The mechanism of suppressive effect of SmBI on aCL induced by beta2-GP I may be realized by resuming the elevated TH/TS ratio and IL-2 activity. The state that SmBI have no effect on normal mice indicates that SmBI has selective immunoregulative functive.

Adjuvants, Immunologic↗

PubMed2001

[Technique of implanting 17 alpha-methyltestosterone to induce the sex reversal of Epinephelus malabaricus].

This paper discussed the method of implanting 17 alpha-methyltestosterone to induce the sex reversal of Epinephelus malabaricus, which included chemical treatment, dosage and operating on the fish. After twice implanting of exogenous hormone, the mature females of 3 years old were transformed into functional males. Sperm could be squeezed from 58% of the fish on 139 days after operating, and from 100% on 301 days. When the functional males were used for artificial breeding, the parent fish spawned in a natural way, and 71.03 million larvae were hatched in the two years of 1999-2000. The larvae were used for rearing of fish fry, from which normally growing young fish was get. It is believed that the method of implanting exogenous hormone to induce the sex reversal of E. malabaricus is easy and stable, which can satisfy the requirement of artificial breeding in factories.

Animals↗

PubMed2001

[Complications of third ventriculostomy for hydrocephalus].

OBJECTIVE: To explore the reason of complications of third ventriculostomy and the method for reducing complications. METHODS: Fifteen third ventriculostomies and the related complications were analyzed retrospectively. RESULTS: Two patients had ventricular infection, one subdural fluid collection, one obstraction of fenestration site by neoplasm, one delayed herniation due to hematoma-occupied third ventricle. The complications were due to the inferior quality of the equipment and poor experience. CONCLUSIONS: Advanced equipment and understanding of possible complications can reduce complications.

Adolescent↗

PubMed2001

[N2O emission by trees under natural condition].

The sources of N2O, one of the major greenhouse gases in the atmosphere, are still unclear till now. It was previously thought that only soil microbial process produced N2O. The aim of this study was to provide evidences that plant can emit N2O under the natural condition. The measurement of aboveground vertical profiles of N2O concentrations were conducted within coniferous-deciduous mixed forests in Changbai Mountain, China. Significant high N2O concentrations were found at or near the height of canopy. High concentrations in profiles were 3.03% to 64.9% higher than the "normal concentrations". Differences between the high concentrations and the "normal concentrations" were statistically significant. The simultaneous occurrence of high concentrations at/nearby the canopy height and normal concentrations at the trunk space height indicated an efflux of N2O from foliage to atmosphere. This study afforded evidences supporting that plant per se, besides forest soil, was an important source of atmospheric N2O in a forest ecosystem.

Air↗

PubMed2001

[Orthotopic liver transplantation: report of 70 cases].

OBJECTIVES: To summarize the results of liver transplantation for various end-stage liver diseases at Sun Yat-sen University of Medical Sciences, define the role of liver transplantation in treatment of hepatocellular carcinoma (HCC) and fulminant hepatitis B, and assess the value of lamivudine for preventing HBV recurrence. METHODS: Clinical data of seventy patients undergoing orthotopic liver transplantation (OLT) at Sun Yat-sen University of Medical Sciences between April 1993 and December 2000 were retrospectively analyzed. The main indications for liver transplantation were HCC (26 cases), liver cirrhosis (21), fulminant hepatitis B (12), sclerosing cholangitis (4) and other terminal liver diseases (7). Lamivudine was used in 12 patients with fulminant hepatitis B. Logistic multivariate regression analysis was employed to determine the risk factors predicting outcome of liver transplantation. RESULTS: Fifty-four patients survived for more than one month and 16 patients died within 30 days after OLT. The overall hospital survival rate was 77.1%. The hospital survival rates in Child's A and B patients were 87.5% and 83.3%, respectively. They were superior to those of the Child's C patients (P < 0.05). The outcome of patients with small HCC was superior to that of patients with large HCC. Preoperative APACE III scores, the severity of ascites, and serum creatine level had an independent influence on outcome. Of the patients with fulminant HBV infection, 9 survived for 2-24 months. Treatment with lamivudine monotherapy was both well tolerated and efficacious in patients with fulminant Hepatitis B. CONCLUSIONS: OLT can cure some patients and provide palliation for others with HCC. Patient selection is extremely important for predicting outcome. The results support the application of liver transplantation as a therapeutic modality for various end-stage liver diseases. Lamivudine is effective and safe in OLT for patients with HBV infection.

Adolescent↗

PubMed2001

[The polymorphism of (CAG)n repeats within androgen receptor gene among Chinese male population].

OBJECTIVE: To investigate the polymorphism of (CAG)n repeats within androgen receptor (AR) gene among normal Chinese male population. METHODS: dsDNA cycle sequencing and[alpha-(32)PdCTP] incorporated asymmol/Letric PCR-denaturing polyacrylamide gel electrophoresis(PAGE) were used to determine the number of (CAG)n repeats in normal men (n=107). RESULTS: The number of polymorphic (CAG)n repeats ranges from 11 to 29; the most frequent repeat is 22(20/107); the less frequent repeats are 23(15/107), 24(11/107), 21(11/107) and 20(8/107). CONCLUSION: The AR gene (CAG)n exhibits polymorphism among normal male population and the present work could serve as a basis for further exploration of its pathological and genetic significance.

Adolescent↗