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Biomedical subjects

Z Lei

Publications and source records attributed to Z Lei.

At least 37 records · Page 2Linked to original sources
PubMed2000

Laser acupuncture for adolescent smokers--a randomized double-blind controlled trial.

A double blind, randomized, placebo-controlled clinical study was conducted to evaluate the efficacy of laser acupuncture treatment in adolescent smokers. Three hundred and thirty adolescent smokers at the Smoking Cessation Clinic of Child Guidance Clinic, Institute of Health, Singapore, were randomly assigned in equal numbers to laser acupuncture treatment and sham acupuncture (control) groups. The proportions of patients with complete smoking cessation after completing treatment for four weeks were 21.9% in the treatment group and 21.4% in the control group. At three months post-treatment, the rates for complete cessation were 24.8% and 26.2%, respectively. Thus, there was no significant difference in the rates of smoking cessation in the treatment and control groups.

Acupuncture, Ear↗
PubMed2000

[Synthesis of chimeric anti-MDR1 ribozymes (tRNA-Rzs) and their biological activities in cell-free system].

OBJECTIVE: Development of multidrug resistance(MDR) is the major obstacle to successful cancer chemotherapy. One strategy to block the P-glycoprotein(P-gp)-mediated MDR is to use a ribozyme (Rz) target against MDR1 mRNA. METHODS: Three kinds of anti-MDR1 chimeric hammerhead ribozymes, the first-one cleaving codon 196 of MDR1 mRNA (196MDR1-Rz), the second one, a stem-II base modified (U9-->G9, U13-->A13, G14-->A14, A18-->C18) Rz against codon 196 (196MDR1-sRz) and the third one, the stem-II base modified Rz directed against the -6(-)-4 GUC sequence of the translation initiation site of the MDR1 mRNA (iMDR1-sRz), were synthesized based on the cloned retroviral constructs: N2A + tRNAi(met)-196MDR1-Rz, N2A + tRNAi(met)-196MDR1-sRz, N2A + tRNAi(met)-iMDR1-sRz. RESULTS: In a cell-free system, the chimeric tRNA-sRz molecules were more stable and had more efficient catalytic activities than the corresponding naked Rz molecules. The stem-II base modified Rz molecules were also more stable and efficient in catalytic activities than the unmodified ones. In control, the disabled tRNA-mut-iMDR1-sRz had no cleavage activity. CONCLUSION: Base modification in the Rz's stem-II of ribozyme structure and the development of chimeric tRNA-ribozyme molecules are able to enhance the cleavage efficacy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

[Distribution of HIV resistance CCR5-delta 32, CCR2-64 I and SDF1-3'A alleles and their polymorphisms in the Han population in China].

OBJECTIVE: To study the frequency and polymorphism of three mutations (CCR5(Delta)32, CCR2-64I and SDF1-3'A alleles) conferring resistance to determined HIV-1/AIDS in the indigenous Han population in China. METHODS: The study population included 1,267 subjects, of which consisted 98.7% (1,251/1,267) Han people. The genotypes of the three mutations were respectively, detected by polymerase chain reaction (PCR) for CCR5(Delta)32 mutation, or by PCR/RFLP (restriction fragment length polymorphism) assay with the digestion of restriction endonuclease Bsa BI and Msp I for CCR2-64I and SDF1-3'A mutations. DNA sequencing was employed to confirm the accuracy of PCR or PCR/RFLP products. RESULTS: The frequency of the mutant alleles were: 0.00119 for CCR5(Delta)32; 0.20023 for CCR2-64I, and 0.28723 for SDF1-3'A. The three heterozygous CCR5-wt/Delta32 mutants were identified and no homozygotes were detected in indigenous Han population. The frequencies of CCR2-64I and SDF1-3'A alleles in China were higher than those of Caucasians descents in the USA and Europe. CONCLUSION: Our data was the first findings on the frequency and polymorphism of CCR5(Delta)32, CCR2-64I and SDF1-3'A alleles in indigenous Han population in China which implied that the indigenous Han people might have a higher genetic susceptibility to the infection of sexually transmitted HIV-1 (R-5) strain. Further study is needed to clarify the significance of higher frequency of CCR2-64I and SDF1-3'A alleles in Han population.

Alleles↗
PubMed2000

[Polymorphisms of chemokine receptor alleles influencing genetic susceptibility to HIV-1 infection in Mongolia population in China].

OBJECTIVE: Mutant frequency and polymorphism of HIV-1 resistance CCR5-Delta32, CCR2b-64I and SDF1-3'A alleles were investigated in Chinese population from Mongolian ethnic origin. METHODS: Whole blood samples from 134 Mongolian subjects were collected randomly and their genomic DNA were extracted using Qiagen Blood Kit. Allelic frequency was identified by means of PCR or PCR-RFLP analysis. Allelic polymorphism in population and between sex in the sample as well as correlation of the three genes were analyzed by chi(2) test. RESULTS: The frequencies of the three alleles were as following: CCR5-Delta32 1.1%, CCR2b-64I 24.8% and SDF1-3'A 22.0% respectively. Distribution of the three mutant alleles among the Mongolian population was in accordance with Hardy-Weinberg equilibrium. Statistical analysis showed there was a higher frequency of CCR2b-64I in female than in male subjects (29.2% vs 19.7%). No Statistical difference was found in the allelic frequencies of both CCR5-Delta32 and SDF1-3'A between male and female individuals. CONCLUSION: Compared with the Caucasian American, there were higher frequencies of CCR2b-64I and SDF1-3'A alleles and lower frequency of CCR5-Delta32 allele found in Mongolian population while the factors responsible for the variation of genetic polymorphisms in different ethnic populations need to be clarified.

Adolescent↗
PubMed1999

[Effects of cooking oil fume condensate on cellular immunity and immunosurveillance in mice].

Rapeseed oil fume, soyabean oil fume and salad oil fume condensate were injected respectively to female Kunming mice. The results showed that, compared to control group, in mice exposed to low level of rapeseed oil fume condensate, the delayed hypersensitivity responses were inhibited, while in mice exposed to high level of that, the delayed hypersensitivity responses and the NK cells activity were inhibited. In mice exposed to high level of soyabean oil fume condensate the delayed hypersensitivity responses, the NK cells activity and CaM activity were inhibited. The results of these parameters were all statistically significantly different from those in control mice. In mice exposed to low level of salad oil fume condensation, the delayed hypersensitivity responses and the NK cells activity were significantly inhibited. The results indicated that cooking oil fume could affect immune system of animals.

Air Pollutants↗
PubMed1999

An evaluation of mattress encasings and high efficiency particulate filters on asthma control in the tropics.

The effect of two allergen avoidance modalities, Allergy Control Covers (ACC) and High Efficiency Particulate Filters (HEPA) on asthma control in children were evaluated. This was an open study involving 24 dust mite sensitive asthmatic children. Following a 4 week run-in period, the subjects were randomly allocated to use mattresses fitted with ACC (n = 6), HEPA filters in their bedrooms (n = 12) or act as controls (n = 6) for a study duration of 4 months. Measurements of the major Dermatophagoides spp. mite allergens, Der p 1 and Der f 1, levels in dust samples obtained from mattresses were made at baseline, 1, 2 and 4 months post implementation. Daily symptom scores including morning and evening peak flow readings, and monthly spirometry and exercise bronchoprovocation tests were carried out Our results showed that dust mite allergen levels in mattresses fell at 1 and 2 months post implementation in the ACC group (p<0.05). In contrast, no decrease in allergen levels was seen in the HEPA and control group. At the end of the 16 weeks, only the ACC group showed improvement in FEV1 and reduction in diurnal peak expiratory flow rate (p<0.05). Improvement in mean symptom scores was also observed for both the ACC and HEPA groups, but not the control groups (p<0.05). Although the numbers in this study were small, the results Indicate that the effectiveness on mite exposure barrier covers was short-lived, and the improvement in asthma control though documented was not obvious.

Adolescent↗
PubMed1999

[Evaluation of safety in Chinese women with amenorrhea following injection of depot-medroxyprogesterone for contraception].

OBJECTIVE: To determine whether serum estradiol (E2) level was low after Depot-medroxyprogesterone (DMPA) induced amenorrhea for contraception, thus to evaluate the safety of using DMPA. METHODS: Forty four Chinese women with amenorrhea after injecting DMPA were investigated, and the median period of amenorrhea was 18 months. Symptoms, pelvic examination, serum E2 and follicular stimulating hormone (FSH) levels, and vaginal cytology were examined. RESULTS: Women with amenorrhea had neither symptoms nor genital atrophy that similar to menopausal syndrome. The median level of serum E2 was 150.5 pmol/L (equal to the level of early follicular phase), and the median level of serum FSH was 14.0 IU/L. There were no correlation between E2 and FSH levels, and no correlation between amenorrhea period and E2 or FSH levels (P > 0.05) as well. No significant relationship between estrogen effects by vaginal cytology and the time period of amenorrhea was found. However, the estrogen effect was significantly correlated to the interval from last injection to vaginal smear tested. CONCLUSION: It could be concluded that though DMPA may induce amenorrhea, it will not lower serum E2 levels, and the inhibition of ovarian function is reversible.

Adult↗
PubMed1999

[Determination of itaconic acid in culture broth by high performance liquid chromatography].

An HPLC method for the determination of itaconic acid and other components in the culture broth of Aspergillus terreus was developed. The operating conditions were Aminex HPX-87H column (300 mm x 7.8 mm) at 30 degrees C, mobile phase of sulfuric acid (4 mmol/L) and refractive index detector at 30 degrees C. The linear relationship of calibration curve was good in the range of 0-50 g/L for itaconic acid (r = 0.9997). The detection limit was 5.7 micrograms, and the relative standard deviation was 1.37% (n = 7). Other components in the culture broth were SO(4)2-, sucrose, glucose and fructose. The method is simple, sensitive, rapid and accurate.

English Abstract↗
PubMed1998

Mitogen-activated protein kinase is involved in epidermal-growth-factor-regulated protein phosphorylation in nuclear membranes isolated from JEG-3 human choriocarcinoma cells.

The treatment of highly purified nuclear membranes isolated from JEG-3 human choriocarcinoma cells with epidermal growth factor (EGF) resulted in an increase of the receptor autophosphorylation and the phosphorylation of several other proteins, including 44-kDa, 34-kDa and 24-kDa proteins, and a decrease in the phosphorylation of a 40-kDa protein. The kinetics of phosphorylation and the use of RG-13022, a selective inhibitor of EGF-receptor kinase activity, suggested that receptor activation was necessary for the phosphorylation response of the other proteins. Tyr was exclusively phosphorylated in the EGF receptor and 24-kDa proteins, Tyr and Thr were phosphorylated in the 44-kDa protein, and Ser was phosphorylated in the 34-kDa protein and dephosphorylated in the 40-kDa protein. The molecular size, Thr/Tyr phosphorylation, immunoprecipitation and enzymatic activity towards myelin basic protein suggested that the 44-kDa protein was a mitogen-activated protein (MAP) kinase. The EGF treatment not only increased phosphorylation but also catalytic activity of MAP kinase and these increases were prevented by the addition of RG-13022. In summary, this report demonstrates that target cell nuclei contain EGF receptors, which use the MAP kinase signaling pathway.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1998

Localization of receptors for luteinizing hormone/chorionic gonadotropin in neural retina.

Although the expression of the luteinizing hormone (LH)/human chorionic gonadotropin (CG) receptor gene has been traditionally thought to be restricted to gonadal tissue, recent studies have shown that LH/CG receptors are present in many regions of the central nervous system (CNS), as well as in peripheral tissues. We now report the characterization of LH/CG receptor gene expression in the neural retina, a component of the CNS. Transcript levels in the retina are approximately equal to levels present in the cerebral cortex, but are at least 100 fold lower than the levels in testis. The density of LH/CG receptor transcripts, receptor protein and 125I-CG binding is the highest in the photoreceptor cells and then decreased throughout the inner retina. Our study is the first to demonstrate the presence of LH/CG receptors in the neural retina. This finding raises the possibility that photoreceptor cells have the potential to mount cellular responses to LH/CG that may impact on visual processing, and poses an intriguing connection to the proposed role of gonadotropins in the progression of proliferative retinopathy.

Animals↗
PubMed1998

[Identification of Listeria monocytogenes by PCR method].

OBJECTIVE: To establish a rapid, sensitive and specific polymerase chain reaction (PCR) method for detection of Listeria monocytogenes (LM). METHODS: A pair of oligonucleotide primers were designed with hylA gene as target sequence. Fiftyfour strain of standard LM and 21 strains of irelevant bacteria were amplified and confirmed by PCR technique. Thirty-three strains of listeria isolated from food at home were identified by PCR and routine methods. RESULTS: A 743-bp DNA fragment with a conservative Hind II site could be amplified by PCR, showing excellent features of LM. Limit to detection for pure culture was 55 colony forming units (CFU). Eighteen of 54 strains were identified as LM by both methods, with a completely coincident result. PCR was strongly inhibited as used in detection for food. If food was cultured for 25 hours for proliferation in listeria enrichment broth, then the culture was chemically extracted, the purified bacteria after heat lysis could react as PCR templates and the inhibitory effects could be greatly reduced. Milk inoculated artificially with four colony forming units of LM could be specifically detected by PCR. CONCLUSION: PCR can be used in rapid, sensitive and specific identification of LM.

Animals↗
PubMed1998

[Bcl-2 oncoprotein expression in head and neck malignant neoplasm].

To investigate the expression of the apoptosis-suppressing protein Bcl-2 in head and neck neoplasm and the relationship between Bcl-2 and p53 oncoprotein, 90 malignant tumours and 20 benign diseases were studied with immunohistochemical LSAB(labeled streptavidin biotin) method. The results indicated that 48.9% (44/90) cases of head and neck malignant tumours were Bcl-2 positive, and all benign diseases were negative. The expression rate of Bcl-2 in head and neck squamous carcinoma (59.6%) was obviously higher than adenocarcinoma (24.8%), undifferentiated tumour (33.3%) and malignant lymphoma (P < 0.05). The expression rate of Bcl-2 in p53-positive tumours was significantly higher in p53-negative neoplasm. The positive rate of Bcl-2 oncoprotein was not connected with clinical stage and pathological grade. The positive staining intensity was significantly related with clinical stage. This study suggested that Bcl-2 oncoprotein may play an important role in the development of head and neck tumour.

Adenocarcinoma↗
PubMed1997

cis-Acting elements and trans-acting proteins in the transcriptional inhibition of gonadotropin-releasing hormone gene by human chorionic gonadotropin in immortalized hypothalamic GT1-7 neurons.

We investigated the cis-acting elements and trans-acting proteins required for the transcriptional inhibition of the gonadotropin-releasing hormone (GnRH) gene by human chorionic gonadotropin (hCG) in GT1-7 neurons. Transient transfection of GT1-7 neurons with the 5'-flanking region of the rat GnRH gene-luciferase fusion constructs revealed that a 53-base pair (bp) sequence between -126 and -73 bp is required for the hCG inhibition. Nuclear extracts from GT1-7 neurons contained 110- and 95-kDa proteins that formed two complexes with the 53-bp sequence. These proteins are not related to Fos, cAMP response element-binding protein, Oct-1, or progesterone receptors, and hCG treatment selectively increased the 95-kDa protein. DNase I footprinting with GT1-7 cell nuclear extracts protected the -99 to -79-bp region, which contained a so-called imperfect AP-1 site (-99 to -94 bp) and two AT-rich palindromic sequences (-91 to -87 bp and -85 to -81 bp). The mutagenesis of the AT-rich regions, but not the AP-1 site, resulted in a loss of DNA binding of the 95-kDa protein and the inhibitory effect of hCG. In summary, our results are consistent with hCG inducing a 95-kDa trans-acting protein, which binds to -91- to -81-bp AT-rich sequences in the 5'-flanking region to inhibit the transcription of the GnRH gene.

Animals↗
PubMed1997

[Comparison of anti-hepatitis C virus (HCV) IgM and HCV-RNA detection in serum samples of patients with HCV infection].

Anti-HCV IgG is the routine assay for the diagnosis hepatitis C. But the method is ineffective in early detection of hepatitis C. We have detected anti-HCV IgM in hospital hepatitis C patients by Enzyme-Linked Immunosorbent Assay (ELISA) and compared the results with those of HCV-RNA and total antibody. Our studies indicate that anti-HCV IgM is detected in all hepatitis C marker positive sera. But the amount of anti-HCV IgM in HCV-RNA positive sera is significantly higher than that of in the corresponding negative sera. This subjects that anti-HCV IgM and HCV-RNA are somewhat correlated and they have different clinical interests. Anti-HCV IgM can be expected and hepatitis activities and its actual clinical interests are to be further studied.

Antibodies, Anti-Idiotypic↗
PubMed1997

Haemostatic properties of human pulmonary and cerebral microvascular endothelial cells.

Little is known on the haemostatic profiles of human microvascular endothelial cells (MVEC) from different tissues. In addition it is not known whether MVEC from patients display the same haemostatic pattern as MVEC coming from healthy controls. To address these questions MVEC from human lung and brain were isolated and stimulated with tumour necrosis factor alpha (TNF) and E. coli lipopolysaccharide (LPS) for 24 h. The level and the kinetics of procoagulant activity (PCA) and thrombomodulin (TM) expression were found to be different depending on the tissue of origin and on the agonist used. In particular, the inducible PCA was higher in lung than in brain MVEC, an observation that may be related to the frequency of lung involvement in septic shock. Differences were also observed for tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1) with MVEC supernatants or cell lysates. These variables were then measured in lung MVEC purified from patients with acute respiratory distress syndrome (ARDS) and compared to controls. Cells from ARDS patients constitutively expressed more PCA and PAI-1 than controls. The fibrinolytic potential, expressed as t-PA/PAI-1 ratio, was lower in ARDS than in lung MVEC. It is concluded that MVEC display different haemostatic features depending on the tissue they come from and that lung MVEC from ARDS patients present a procoagulant profile when compared with those from controls.

Adult↗
PubMed1997

[Effect of pretreatment counseling on discontinuation rates in women given depo-medroxyprogesterone acetate for contraception].

OBJECTIVE: To investigate the effect of pre-treatment counseling on discontinuation rates of 150 mg depo-medroxyprogesterone acetate (DMPA), given for contraception. METHODS: A total of 421 women participated, 204 receiving intensive structured pre-treatment and on going counseling on the hormonal effects and probable side effects of DMPA and 217 receiving only routine counseling. All participants were followed up at every 3 months for 1 year. The primary endpoint was termination rate, secondary endpoints were frequency of medical events and reasons for termination. RESULTS: The most common reasons for terminating DMPA were menstrual changes. Although women in the intensive structured counseling group reported more menstrual irregularity (39.7%) than did women in the routine counseling group (26.3%), study termination rates were significantly lower in the intensively structured counseling group than in the routine counseling group. At one year, the total cumulative termination rates were 11.3% (23/204) and 42.4% (92/217), respectively (P < 0.0001). No pregnancy and serious medical events were reported. CONCLUSION: Pre-treatment counseling on expected side effects increases the acceptability of DMPA.

Adolescent↗