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Biomedical subjects

G Chen

Publications and source records attributed to G Chen.

At least 505 records · Page 28Linked to original sources
PubMed1998

[Genetic polymorphisms of the D19S400 locus in Chinese Zhuang, Bai, Tibetan, Mongolian populations].

Four Chinese populations have been studied by the polymerase chain reaction (PCR) for obtaining the data on genetic polymorphisms of D19S400 locus in four populations in China and for evaluating its use in forensic practice. EDTA-blood samples were collected from 356 unrelated individuals in Nanning (Zhuang), Dali (Bai), Lasa (Tibetan); Hailaer (Mongolian), DNA samples were extracted by Phenol/Chloroform method. The PCR products were analyzed by PAG vertical electrophoresis. Nine alleles and 42 genotypes were found at D19S400 locus in these four populations. The heterozygosity was between 0.75 and 0.89 and the discriminating power between 0.9274 and 0.9625. Significant difference was observed in the distribution of allele frequencies among the four Chinese populations. According to the results obtained in this study, D19S400 locus is a useful marker for individual indentification, paternity testing and for genetics study.

Alleles↗
PubMed1998

[Observation of enalapril on treating the patients with left ventricular diastolic dysfunction].

The effects of enalapril on 50 patients with left ventricular diastolic dysfunction (LVDD), confirmed by clinical features and radionuclid ventriculography, were assessed in a randomized, double-blind, and controlled method for eight weeks. The results showed that left atrial diameters (LAD), interventricular septum thicknesses (IVST) and left ventricular mass indexes (LV-MI) except left ventricular diameters (LVD) were decreased in the enalapril treatment group. The left ventricular diastolic function parameters such as the early peak filling velocity (EPAV), the atrial peak filling velocity (APAV), the deceleration of early peak filling velocity (DC) and the isovolumic relaxation time (IRT) were improved, the NYHA class and the exercise tolerance were increased, the left ventricular ejection fraction (LVEF), and the cardiac index (CI) were not altered in the enalapril treatment group. The patients with LVDD were well tolerated with enalapril. The parameters mentioned above were not altered in control group. It is suggested that enalapril is an effective drug in the treatment of LVDD.

Adult↗
PubMed1998

[Serum level of granulocyte colony stimulating factor in severe aplastic anemia patients].

OBJECTIVE: To investigate the relationship between serum level of granulocyte colony stimulating factor (G-CSF) and clinical status, treatment outcome and prognosis in severe aplastic anemia (SAA-I) patients. METHODS: Serum G-CSF level was detected by ELISA assay in 36 SAA-I patients. RESULTS: Pre-treatment serum G-CSF levels of 27/36 (75%) SAA-I patients were above normal. These patients achieved better curative outcomes in a shorter period of treatment. CONCLUSION: Detection of serum G-CSF level in SAA-I patients is helpful for judging the clinical status and prognosis.

Adolescent↗
PubMed1998

[Clinical analysis of 164 cases Coombs test positive autoimmune hemolytic anemia].

OBJECTIVE: To analyze the clinical features and treatment outcomes of autoimmune hemolytic anemia (AIHA). METHODS: Coombs test positive AIHA patients were retrospectively analyzed. RESULTS: Patients with AIHA were predominantly female, secondary AIHA accounted for 49% of the total cases, mainly associated with connective tissue diseases. In most cases of AIHA, the anti-red cell antibodies were IgG plus C3, while patients with IgG plus IgM had more severe clinical manifestations. The response rate of adrenocortical hormones and cyclosporin A (CsA) was 90.9%. CONCLUSION: Adrenocorticosteroids is still the first choice of therapy for AIHA, CsA can improve the response rate.

Adolescent↗
PubMed1998

Pharmacokinetics of intravenous arsenic trioxide in the treatment of acute promyelocytic leukemia.

OBJECTIVE: To study the pharmacokinetics and metabolism of arsenic trioixide (As2O3) and its main side effects. METHOD: As2O3 was administered intravenously at the dose of 10 mg per day for the treatment of 8 relapsed acute promyelocytic leukemia (APL) patients. The arsenic content was measured by Gas-phase chromatography. RESULTS: The plasma maximal concentration (Cpmax) was 0.94 +/- 0.37 mg/L (x +/- s), time to peak concentration (Tp) was 4 hours, plasma distribution half-time (t1/2 alpha) and elimination half-time (t1/2 beta) were 0.89 +/- 0.29 hours and 12.13 +/- 3.31 hours, respectively. Apparent distribution volume (Vc) was 3.83 +/- 0.45 L, system clearance (CLs) was 1.43 +/- 0.17 L/h, and area under curve (AUC) was 7.25 +/- 0.97 mg.h/L. The continuous administration of As2O3 did not alter its pharmacokinetic behaviors. During As2O3 treatment, 24-hour arsenic content in urine accounted for 1%-8% of the daily dose (10 mg). When arsenic accumulation in hair and nail increased continuously, the peak concentration could be five to seven-fold higher than that of pre-treatment. Importantly, arsenic contents in both urine and hair or nail declined gradually after drug withdrawal. No bone marrow suppression or severe organ-impairment was found. CONCLUSION: As2O3 is a relatively safe and effective remedy in the treatment of patients with relapsed APL, in spite of certain degree of arsenic accumulation in some tissues.

Adolescent↗
PubMed1998

[Effect of nitric oxide release on epileptiform discharge in CA1 area of hippocampal slices].

Using a nitric oxide (NO)-sensitive platinum microelectrode (SNM) modified with chitosan nickel (II) complex and Nafion (Nafion-CTS (Ni)-Pt), we observed the effect of nitric oxide synthase (NOS) inhibitor 7-nitro-indazole (7-NI) and N omega-nitro-L-arginine (L-NNA) on penicillin-treated hippocampal slices by simultaneously recording the stimulus-evoked field potentials and nitric oxide release from CA1 pyramidal neurons. Our results show: (1) The linear relationship range and detection limit of SNM were 4.5 x 10(-4)-1.0 x 10(-8) mol/L and 5.0 x 10(-8) mol/L respectively. (2) Penicillin (PEN) could elevate NO release, the number and amplitude of stimulus-evoked field potentials spike (SEPS) in concentration-dependent manner; (3) Both 7-NI and L-NNA depressed NO release and partly reversed the effect of penicillin. The above findings suggest that convulsant provoking effect of NO could be inhibited by NOS inhibitors. The NO-sensitive electrode may provide an useful tool for continuous detection of NO in biological tissues.

Animals↗
PubMed1998

[The choice of methods of intraocular lens implantation in traumatic cataract in the absence of capsular and zonular support].

OBJECTIVE: To study the choice between the methods of anterior chamber intraocular lens (AC-IOL) implantation and posterior chamber IOL suture fixation in traumatic cataract without posterior capsular support. METHODS: The study included 86 cases (86 eyes) with traumatic cataract. A new flexible open-loop one piece PMMA IOL was implanted in the AC-IOL group of 56 cases (56 eyes); fixation of a C-loop one piece PMMA IOL at ciliary sulcus with two sutures was performed on 30 cases (30 eyes) in the posterior chamber IOL (PC-IOL) group. RESULTS: The follow-up period was 1 - 42 months. The visual acuity 0.5 or better was in 71.4% (40/56) in AC-IOL group, in 90.0% (27/30) in PC-IOL group; 1.0 or better was in 39.3% (22/56) in AC-IOL group, in 46.7% (14/30) in PC-IOL group. CONCLUSION: Both AC-IOL implantation and PC-IOL suture fixation are the remedy methods when the PC-IOL intracapsular implantation is unsuccessful. The AC-IOL is suitable for old persons with good anterior segment (cornea, iris and the angle of anterior chamber) and poor posterior segment (vitreous, retina) situations, while the PC-IOL suture fixation is suitable for the young with relatively poor anterior segment and good posterior segment conditions.

Adolescent↗
PubMed1998

[A program of HLA system for parentage testing and its application].

A software of the HLA blood group system for parentage testing was developed with FoxPro 2.5 system. Chinese prompts helped to follow the process during program running. It is easy to use. 63 cases of parentage testing in our department were calculated, and the results were identical with those of manual calculation. It was believed that this program is useful in the parentage testing.

Blood Group Antigens↗
PubMed1998

[A quick algorithm for detecting macro-particles distributed rarefiedly].

This paper presents a simple and quick algorithm, based on the principle of OR operation, for detecting macro-particles when the distribution of macro-particled is few and scattered. Counting and measuring the basic size parameters of macro-particles will be simultaneously accomplished by scanning the macroparticle image only once time.

Algorithms↗
PubMed1998

[DNA vaccine of Plasmodium falciparum: immune response of BALB/c mice induced by injection of the recombinant plasmid DNA].

AIM: To observe the level of immune responses of BALB/c mice induced by direct injection of the recombinant plasmid DNA and to provide evidence for the application of DNA vaccine of Plasmodium falciparum (P. f.) in animals and humans. METHODS: The recombinant plasmid pcDNA3-Pf8 encoding the hybrid antigens of PfCMR-MSP1(19) was constructed. The presence of Pf8 plasmid was detected in the muscle, liver, kidney, heart, spleen and lung by PCR. ELISA, T lymphocyte transformation test, inhibitory assay of the growth and development of P. f. in vitro were used to determine the level of humoral and Th-cell responses. RESULTS: pcDNA3-Pf8 was amplified by PCR technique in the different tissues from BALB/c mice which were injected with pcDNA3-Pf8. The immune serum was specifically recognized by the soluble antigens of P. falciparum (titer: 1:2,560 by ELISA). The specific proliferative response of spleen T cells from immunized mice was remarkably higher than that of control group, the transformation rate being up to 32.82 +/- 3.64%. The immune serum could also inhibit the growth and development of the erythrocytic stages of P. falciparum in vitro. CONCLUSION: Direct injection with the recombinant plasmid pcDNA3-Pf8 specifically elicits BALB/c mice to generate humoral and cell-mediated immune responses, the resulting immune serum being inhibitory to the growth and development of P. f. in vitro.

Animals↗
PubMed1998

[Cloning and sequencing of cDNA in NS3 region of Chinese hepatitis G virus isolated from Henan Province].

To study the genetic characteristics of non-structural region 3 of HGV in China, a HGV-RNA positive sample was collected from Henan. HGV RNA was extracted and amplified by RT-nested-PCR. We got four overlap fragments and they were cloned into plasmid vector pcDNA II. The cDNA was sequenced by the Sanger's method. Nucleotide homology between Henan strain and other reported HGV isolates (PNF2161, R10291, GBV-C) was 85.7% to 93.8% over the 2137 nucleotides examined. Comparison of amino acid sequence deduced from Henan strain with that of other isolates showed 96.1% to 97.7% homology. Three amino acid variations were found in NS3 region of all the three Chinese isolates of HGV. In addition, a N-glycosylation site was found in the NS3 region of all the six isolates.

Amino Acid Sequence↗
PubMed1998

[Detection of hepatitis G virus infection among clinical patients with hepatitis/liver diseases in China by reverse transcription-nested polymerase chain reaction].

According to two highly conserved genome sequences within the helicase(NS3) region and 5'-uncoding(5' UTR) region, we designed two sets of primer pairs to detect HGV RNA by RT-nested PCR in order to study HGV infection in Chinese population. Three hundred and fifty-four serum specimens of various liver diseases were collected from Beijing, Qin Huangdao and Henan areas. Seventy-nine out of 354(22.3%) specimens were HGV RNA positive. Among 254 known clinical hepatitis/liver disease samples, 50(19.6%) were HGV RNA positive. Thirteen HGV RNA positive samples(30.2%) were derived from 43 cryptogenic or nonA-E hepatitis. In 57 commercial blood donors who were antibody positive to HCV 16(30.2%) were HGV RNA positive, suggesting HGV infection is common in various population. It may be an etiological factor which leads to nonA-E hepatitis and post-transfusion hepatitis.

5' Untranslated Regions↗
PubMed1998

[Transient response in electric measurement of human auricular point].

This is an experiment on the measuring E approximately t and R approximately t for human auricular point, which shows there is a transient response of electric potential E(t) and voltage drop U(t) when t < 2 tau and there is at intervals change with the time after 2 tau about R(t) and E(t). We have obtained a response function of the E(t) and U(t) by the circuit analysis. The parameter of the transient character is relaxation time tau, tau approximately RC. The mathematical model is in correspondence with the experimental result of the auricular point and TPM simulation. It indicates that the character changing with the time should be extracted after 2 tau. This experiment is of importance to understanding the electric character of the otopoint.

Acupuncture Points↗
PubMed1998

[Transient response in electric measurement of human auricular point].

This is an experiment on the measuring E-t and R-t for human auricular point, which shows there is a transient response of electric potential E(t) and voltage drop U(t) when t < 2 tau and there is at intervals change with the time after 2 tau about R(t) and E(t). We have obtained a response function of the E(t) and U(t) by the circuit analysis. The parameter of the transient character is relaxation time tau,tau approximately RC. The mathematical model is in correspondence with the experimental result of the auricular point and TPM simulation. It indicates that the character changing with the time should be extracted after 2 tau. This experiment is of importance to understanding the electric character of the otopoint.

Acupuncture Points↗
PubMed1998

Vasectomy reversal associated with increased reactive oxygen species production by seminal fluid leukocytes and sperm.

PURPOSE: Reactive oxygen species, which are primarily produced by leukocytes, are generally detrimental to sperm. High reactive oxygen species levels are found in men with abnormal sperm function. Since men often have poor sperm characteristics and infertility after vasectomy reversal, we compared reactive oxygen species in seminal cells of men after vasovasostomy to those of fertile men to determine if reactive oxygen species were elevated in the former group. MATERIALS AND METHODS: We studied semen samples of men with proved fertility (39) and those with previously proved fertility who had undergone vasectomy reversal (45). The presence of leukocytes was determined by Bryan-Leishman staining. Reactive oxygen species endogenous activity was monitored by luminol dependent chemiluminescence in washed cells, including all cells in the semen, and Percoll density gradient purified sperm. RESULTS: After vasovasostomy men had significantly lower sperm concentration, motility and computerized motility measurements than fertile men. Mean reactive oxygen species in washed seminal cells after vasovasostomy was 684 relative light units per second compared to 49 for fertile controls (p < 0.0001). Density gradient purified sperm had 53 and 0.64 relative light units per second, respectively (p < 0.0001). When men with leukocytospermia were excluded from analysis, differences between the groups remained, although 9 times more reactive oxygen species were detected in men after vasectomy reversal with than those without leukocytes in semen. CONCLUSIONS: Higher levels of reactive oxygen species are found in washed seminal cells and purified sperm after vasectomy reversal than in those of fertile men. Although leukocytes are probably a significant source of reactive oxygen species in these groups, they may not account for all of the increased reactive oxygen species after vasovasostomy. Low motility after vasectomy reversal may be related to the detrimental effects of reactive oxygen species produced by leukocytes or sperm, even in men without clinical leukocytospermia.

Adult↗
PubMed1998

[Occurrences of penicillin-binding protein 2B gene in clinically isolated penicillin-resistant Streptococcus pneumoniae].

We analyzed 88 strains of Streptococcus pneumoniae (S. pneumoniae) isolated in Showa University Hospital from June 1995 to July 1996. The ratios of antibiotic resistance were 39% to penicillin G, 50% to erythromycin, and 2% to imipenem. No resistant to cefotaxime and ofloxacin was observed. Thirty-four strains (39%) were considered to be penicillin-resistant S. pneumoniae (PRSP) strains (MIC of penicillin G > or = 0.5 microgram/ml), according to the breakpoint determined by the Japanese Working Group for Penicillin-Resistant Streptococcus pneumoniae. The ratio of PRSP was higher in S. pneumoniae isolated from inpatients (25/47) when compared to that from outpatients. By PCR analysis, DNA regions of autolysin were amplified in all the 88 strains, confirming that the isolates were S. pneumoniae. Penicillin-binding protein 2B (PBP2B) class B region was positive in 32 strains, and PBP2B class A was in 2 strains. Twenty eight of 34 strains of PRSP contained the PBP2B class B gene. In the remaining six PRSP strains, neither the PBP2B class A nor B region was amplified. The PBP2B class B region was detected as a 180-kb fragment of SmaI digestion of S. pneumoniae DNA by Southern blot analysis, confirming that the detection of PBP2B class B gene by PCR is reliable. We concluded that the PBP2B class B gene is considered to be a major gene responsible for phenotypic resistance of PRSP. We performed genotyping by SmaI digestion pattern using pulsed field gel electrophoresis. No identical pattern was observed in isolates from inpatients, suggesting that apparent nosocomial infection of S. pneumoniae was negligible.

Aminoacyltransferases↗
PubMed1998

Corrosion resistance and ion dissolution of titanium with different surface microroughness.

In vitro corrosion resistance and ion dissolution of commercial pure titanium with different surface microroughness are studied adopting constant potential meter and atomic absorption spectroscopy. In terms of the surface roughness, titanium samples are divided into 5 groups: smooth surface, machining surface, 2 different microroughness surfaces and macrorough surface. Each group contains three category samples under different treatments: natural oxidation (24 h exposure to air), oxidation under 400 degrees C (400 degrees C, 45 min thermal oxidation), oxidation under 700 degrees C (700 degrees C, 45 min thermal oxidation). In Hanks corrosion media, comparative studies through constant potential anode polarization curves and titanium release rates of the 5 groups of Ti samples demonstrates that oxidation under 400 degrees C best increase corrosion resistance and decrease ion release sharply, oxidation under 700 degrees C is better than natural oxidation. Ti samples with a different surface roughness all have good corrosion resistance and their corrosion resistance drop with the raising of surface roughness. Comparing with macrorough surface and machining surface, microrough surfaces have better corrosion resistance and a lower ion release rate which are similar to those of smooth surfaces. Moreover, the corrosion resistance of machining surface Ti is the lowest. It is hypothesized that surface treatment methods such as surface thermal oxidation, surface aging and so on will improve the corrosion resistance and decrease the ion release rate of rough surface effectively by increasing the thickness of surface protection film, improving its structural uniformity and facilitating the formation of ordered, compact surface protection film.

Biocompatible Materials↗