AsGa-XI complexes as models for the EL2 center in GaAs.
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Journal Article↗
Biomedical subjects
Q Zhang
Publications and source records attributed to Q Zhang.
Nicotine effects on eicosanoid formation and hemostatic function: comparison of transdermal nicotine and cigarette smoking.
OBJECTIVES: The purpose of this study was to examine the possible role of nicotine in enhancing coagulation and to assess the potential cardiovascular toxicity of transdermal nicotine therapy for smoking cessation. BACKGROUND: Cigarette smoking increases the risks of acute coronary events. A likely contributing mechanism is activation of coagulation. The role of nicotine in enhancing coagulability has not been resolved. METHODS: We compared in a crossover study the effects of cigarette smoking, transdermal nicotine and placebo transdermal nicotine, each for 5 days, in 12 healthy smokers. RESULTS: Cigarette smoking increased the urinary excretion of 11-dehydro-thromboxane B2 (reflecting thromboxane A2 generation) and increased plasma concentration of the platelet alpha-granule constituents, platelet factor 4 and beta-thromboglobulin, compared with placebo treatment, indicating in vivo platelet activation. Cigarette smoking was also associated with higher levels of fibrinogen in plasma. Transdermal nicotine produced plasma levels of nicotine in the same range as those during smoking but had no effect on thromboxane A2 metabolite excretion, platelet alpha-granule release or plasma fibrinogen, compared with placebo. Excretion of 2,3-dinor-6-keto-PGF1 alpha (reflecting prostacyclin generation) was not significantly influenced by any treatment. These results suggest that nicotine as such is not responsible for the platelet activation or elevation of plasma fibrinogen seen in smokers. However, we cannot exclude the possibility that intermittent bolus-like dosing of nicotine from cigarettes could have different effects from those produced by continually released transdermal nicotine. Other findings were that cigarette smoking and transdermal nicotine treatment were both associated with a higher white blood cell count compared with the placebo patch condition, suggesting a direct effect of nicotine to increase circulating white cells. Factor VII coagulant activity (VIIc) was significantly lower during cigarette smoking, than during either nicotine or placebo patch conditions. CONCLUSIONS: Transdermal nicotine has less effect on platelet activation and catecholamine release than does cigarette smoking, and its use in smoking cessation treatment of patients with coronary heart disease is likely to be safer than cigarette smoking.
6-Ketoprostaglandin F1 alpha↗
Characterization of porcine bone sialoprotein: primary structure and cellular expression.
Bone sialoprotein (BSP) is a highly glycosylated and sulphated phosphoprotein that is a major non-collagenous protein of bone. To further characterize the porcine protein and to study its expression during bone formation BSP cDNA clones were isolated from a porcine bone cDNA library. The primary sequence of the protein was derived from the nucleotide sequence of the largest cDNA insert and from the amino-terminal amino acid sequence determined by the automated Edman degradation procedure. When compared with sequences obtained from the human and rat BSPs 74% and 64% of the amino acids, respectively, were identical and a further 11% and 17%, respectively, were conservative replacements. Moreover, 60% of the amino acids in a concensus sequence derived from the primary sequences of mammalian BSPs were conserved with 16% conservative replacements. The two stretches of polyglutamic acid, through which the protein is capable of binding to hydroxyapatite, and an RGD motif that mediates cell attachment are retained in conserved sequences as are a number of potential sites of serine, threonine and tyrosine phosphorylation, glycosylation and tyrosine sulphation. Secondary structure prediction and hydrophilicity analysis indicate that the nascent BSP has an open flexible structure with the potential to form significant amounts of alpha-helix and some beta-sheet. In situ hybridization of fetal porcine bone with cRNA probes to porcine BSP mRNA shows that BSP is specifically expressed in differentiated osteoblasts on the surface of newly-forming bone trabeculae with especially high levels of hybridization at sites of de novo bone formation. The highly conserved features of BSP and its restricted distribution indicate an important role for this sialoprotein in the formation of bone.
Amino Acid Sequence↗
Comparative diversity analysis of RFLPs and isozymes within and among populations of Hordeum vulgare ssp. spontaneum.
DNA restriction fragment length polymorphisms (RFLPs) and isozyme variation were surveyed in 268 accessions of a wild barley (Hordeum vulgare ssp. spontaneum) sampled from diverse ecogeographical areas in Israel and Iran. A total of 24 markers was used: 7 well characterized isozyme loci and 15 DNA probes which detected 17 putative loci and included three classes of DNA sequences (single copy, low copy and repetitive) representing all 7 barley chromosomes. Survey results indicated that both RFLPs and isozymes are highly polymorphic both within and among populations of this wild barley. The number of alleles per locus and average level of diversity do not differ between isozymes and RFLPs. However, the relative amounts of within vs. between population components vary greatly between these two sets of molecular markers. Isozymes demonstrated a larger amount of within population diversity, whereas RFLPs resolved a higher proportion of between population differentiation. Furthermore, RFLPs detected more heterozygosity than did isozymes. Both classes of markers resolved large numbers of multilocus combinations, the majority of which were represented by only one individual in the total sample. Up to 30% of the loci differ among individuals within populations, and about 50% of the loci differ among plants in different populations. While many important aspects of population diversity as determined by RFLPs are significantly correlated with those of isozymes, such correlation values are generally low, indicating that only a small proportion of the genetic variation detected by one class of markers can be predicted by the other.
Alleles↗
Hepatitis B virus genotype A rarely circulates as an HBe-minus mutant: possible contribution of a single nucleotide in the precore region.
The emergence of HBe-minus hepatitis B virus (HBV) mutants, usually through a UAG nonsense mutation at codon 28 of the precore region, helps the virus to survive the anti-HBe immune response of the host. Host and viral factors that predispose to the emergence of such mutants are not well characterized. The fact that the precore region forms a hairpin structure essential for the packaging of viral pregenomic RNA may explain the extremely high prevalence of the UAG mutation at codon 28. It converts a wobble U-G pair in the packaging signal between nucleotide 3 of codon 15 (CCU) and nucleotide 2 of codon 28 (UGG) into a U-A pair. Since genotype A of HBV has a CCC sequence at codon 15, the UAG mutation would, instead, disrupt a C-G pair present in the wild-type virus. This alteration was shown by transfection experiments to greatly compromise the packaging of pregenomic RNA. The implication of this finding was elucidated by molecular epidemiological studies. Genotype A was found to be the most prevalent genotype in the wild-type virus populations in France but was found in only 1 of the 46 isolates of HBe-minus mutants found there. These mutants were contributed chiefly by genotype D, the second most prevalent genotype in France, which is characterized by a CCU sequence at codon 15. The role of the single nucleotide at codon 15 was confirmed by the finding of the single genotype A isolate in which both wild-type and mutant viruses were present. Interestingly, nearly all of the mutants had a codon 15 sequence of CCU instead of the CCC present in the wild-type viruses. Our results suggest that genotype A of HBV rarely circulates as HBe-minus mutants, probably because of a requirement for a simultaneous sequence change at codon 15. These data, together with the virtual absence of genotype A in the Chinese samples examined, may provide some insights into the uneven prevalence of HBe-minus mutants in the world.
Base Composition↗
Transcriptional activation of human zeta 2 globin promoter by the alpha globin regulatory element (HS-40): functional role of specific nuclear factor-DNA complexes.
We studied the functional interaction between human embryonic zeta 2 globin promoter and the alpha globin regulatory element (HS-40) located 40 kb upstream of the zeta 2 globin gene. It was shown by transient expression assay that HS-40 behaved as an authentic enhancer for high-level zeta 2 globin promoter activity in K562 cells, an erythroid cell line of embryonic and/or fetal origin. Although sequences located between -559 and -88 of the zeta 2 globin gene were dispensable for its expression on enhancerless plasmids, they were required for the HS-40 enhancer-mediated activity of the zeta 2 globin promoter. Site-directed mutagenesis demonstrated that this HS-40 enhancer-zeta 2 globin promoter interaction is mediated by the two GATA-1 factor binding motifs located at -230 and -104, respectively. The functional domains of HS-40 were also mapped. Bal 31 deletion mapping data suggested that one GATA-1 motif, one GT motif, and two NF-E2/AP1 motifs together formed the functional core of HS-40 in the erythroid-specific activation of the zeta 2 globin promoter. Site-directed mutagenesis further demonstrated that the enhancer function of one of the two NF-E2/AP1 motifs of HS-40 is mediated through its binding to NF-E2 but not AP1 transcription factor. Finally, we did genomic footprinting of the HS-40 enhancer region in K562 cells, adult nucleated erythroblasts, and different nonerythroid cells. All sequence motifs within the functional core of HS-40, as mapped by transient expression analysis, appeared to bind a nuclear factor(s) in living K562 cells but not in nonerythroid cells. On the other hand, only one of the apparently nonfunctional sequence motifs was bound with factors in vivo. In comparison to K562, nucleated erythroblasts from adult human bone marrow exhibited a similar but nonidentical pattern of nuclear factor binding in vivo at the HS-40 region. These data suggest that transcriptional activation of human embryonic zeta 2 globin gene and the fetal/adult alpha globin genes is mediated by erythroid cell-specific and developmental stage-specific nuclear factor-DNA complexes which form at the enhancer (HS-40) and the globin promoters.
Base Sequence↗
Relaxin stimulation of porcine granulosa cell deoxyribonucleic acid synthesis in vitro: interactions with insulin and insulin-like growth factor I.
Relaxin (RLX) is a product of the theca interna layer of the developing pig follicle. However, its physiological role within the ovary is unknown. The purpose of this study was to determine the effects of RLX alone or in conjunction with insulin and insulin-like growth factor-I (IGF-I) on porcine granulosa cell (GC) DNA synthesis and proliferation in vitro. The results showed RLX (1-1000 ng/ml), insulin (1-1000 ng/ml), and IGF-I (1-30 ng/ml) alone stimulated [3H]thymidine incorporation into DNA by GC from small, medium, and large porcine follicles (P < 0.05). The effect of RLX in combination with insulin or with IGF-I on DNA synthesis by GC from small and medium follicles was greater than the effect of either single factor (P < 0.05). In the large follicle, RLX increased GC DNA synthesis synergistically with insulin and IGF-I. FSH (100 ng/ml) or estradiol (10(-7) M) had no effect on basal or RLX-induced [3H]thymidine incorporation into GC DNA at any stage of follicular development. After 6 days incubation in vitro, RLX dose-dependently increased proliferation of GC from small follicles (P < 0.05). The increased cell number in response to RLX correlates with RLX-induced [3H]thymidine incorporation into DNA by these GC. Hydroxyurea, an inhibitor of DNA synthesis, blocked RLX-induced thymidine incorporation, indicating that the increase in thymidine incorporation in response to RLX was due to DNA synthesis and not repair. This is the first demonstration that RLX acts as a growth factor in the porcine follicle by increasing GC DNA synthesis and proliferation in vitro. RLX enhanced the growth-promoting effects of insulin and IGF-I on GC, which suggests an interaction of RLX with these proteins during follicular growth. These studies support the concept that locally produced thecal RLX alone or in combination with other growth effectors may play a key role in GC growth during porcine follicular development.
Animals↗
Developmental expression of the relaxin gene in the porcine corpus luteum.
Northern analysis and in-situ hybridization were used to follow the development of relaxin gene expression in the newly forming corpus luteum (CL) after ovulation and throughout luteal development. Alkaline phosphatase (AP) was used as a marker of theca-derived lutein cells and the relationship between AP-positive and relaxin mRNA-containing cells was assessed. Ovaries from prepubertal pigs treated with pregnant mares serum gonadotrophin (PMSG)/human chorionic gonadotrophin (hCG) were collected during the periovulatory period and at various times during 19 days after ovulation. In addition, CL from cyclic pigs on days 10 and 16 were used to monitor relaxin gene expression in small and large luteal cells. Northern analysis revealed that relaxin gene expression increased with CL development in the PMSG/hCG-treated pig, reaching maximal levels at around day 14 post-ovulation. Thereafter, as the CL regressed, the level of relaxin mRNA declined. In CL from cyclic pigs at day 10 of the cycle, only small luteal cells expressed relaxin mRNA. However, by day 16 of the cycle, large luteal cells were the source of relaxin gene expression. In-situ hybridization studies revealed that in the early CL (up to 30 h post-ovulation), the relaxin gene transcript was observed in cells along the margins of the CL and in the core of the infolding follicle wall corresponding to the AP-positive, luteinized theca cell layer. As luteinization progressed, the theca and granulosa cell layers could no longer be distinguished morphologically (from 54 h after ovulation until day 9). However, the pattern of relaxin hybridization persisted along the periphery in bands of cells penetrating the CL, and coincided with areas of AP staining, indicating that the theca lutein cells were the site of relaxin gene expression. At day 14, relaxin hybridization and AP staining were distributed throughout the luteal tissue. With CL regression both AP staining and relaxin hybridization declined. This pattern of relaxin hybridization in the CL of the gonadotrophin-primed pig was identical to that observed in cyclic pigs on days 10 and 16 of the cycle. These findings indicate that theca interna cells retain their ability to express the relaxin gene following ovulation and luteinization. In the early CL, the small theca-derived lutein cells are the source of relaxin transcript. However, as the CL becomes fully differentiated, the large granulosa-derived lutein cells acquire the capacity to express the relaxin message.
Alkaline Phosphatase↗
Induction of c-fos expression in the rostral medulla of rats following electroacupuncture stimulation.
The present study was designed to examine the induction of c-fos mRNA and Fos-like protein in the rostral medulla of awake rats following electroacupuncture (EA) stimulation, using in situ hybridization and immunohistochemical method. Rats were subjected to EA stimulation (100 Hz, 1-2-3 mA) for 30 min by inserting two needles into acupoints Zusanli (S36) and Sanyingjiao (Sp6) of each hind leg. Animals were sacrificed 1h and 2h after EA for in situ hybridization and immunohistochemical study, respectively. c-fos mRNA or Fos-like-immunoreactivity (FLI) neurons were densely distributed in the rostral ventromedial medulla (RVM), including raphe magnus nucleus, gigantocellular reticular nucleus, gigantocellular reticular nucleus alpha, as well as intermediate reticular nucleus. Neurons in the solitary tract nucleus also showed c-fos expression. The results suggest that the RVM may be an important region for mediating EA effect.
Afferent Pathways↗
[The multiplication of Sindbis virus in BHK-21 cell].
One step growth curve of Sindbis virus (SbV) in BHK-21 cells showed that a lot of progeny viruses could be observed at 2 hr. after infection. The titer of virus reached the highest about 10(9)TCID50/ml at 6hr. post infection. The viral morphological characters and morphogenetic process in BHK-21 cells were examined by electron microscopic techniques. The dynamics of viral proteins synthesis and the effect on host cell were studied and discussed in this paper.
Animals↗
Sources and biological actions of relaxin in pigs.
Although the major source of relaxin in pigs is the corpus luteum of pregnancy, there is now evidence for relaxin gene expression and translation into protein in the theca interna cells of the preovulatory follicle, the corpus luteum of the cycle and the uterus. The theca interna cells retain their ability to express the relaxin gene and protein following ovulation. During the early stages of development of the corpus luteum, the theca-derived small lutein cells are the source of the relaxin transcript. As the corpus luteum becomes fully functional, there is a switch in the site of relaxin synthesis from small theca-derived lutein cells to large granulosa-derived cells. In the absence of luteolysis, this switch is accompanied by a dramatic rise in relaxin synthesis. Relaxin has been identified in boar seminal plasma and can maintain or increase sperm motility. However, a source of relaxin in the boar has not been identified. Relaxin is an important regulator of uterine function during pregnancy acting systemically to suppress myometrial activity and promote cervical dilation at parturition. The changes in thecal relaxin production during follicle development and its ability to promote growth and changes in proteolytic enzyme activity of granulosa cells in vitro have led to the concept of an autocrine or paracrine role for relaxin within the follicle. Uterotrophic effects of relaxin have been reported in rodents and swine and support the hypothesis that relaxin promotes uterine growth and expansion in early pregnancy to accommodate the growing fetuses. Mammotrophic effects of relaxin in rodents have now been extended to pigs, with evidence that relaxin is necessary for normal mammary parenchymal development in late pregnancy. In most instances the mechanisms responsible for, and the physiological significance of, these diverse biological effects remain to be elucidated.
Animals↗
Virus DNA detection of herpes simplex keratitis by PCR.
HSV-DNA of seven corneal lesions suspected with herpes simplex keratitis (HSK) and nine normal human donor corneas were detected by PCR. Five out of seven diseased corneas showed positive results, and the other two diseased corneas and nine normal corneas negative. The results suggest the PCR may be useful as a rapid and sensitive method for diagnosing HSK.
Adult↗
Nylestriol replacement therapy in postmenopausal women. A three-year prospective study.
A three-year prospective study was carried out in 283 postmenopausal women to evaluate the effects of a long-acting estriol derivative-nylestriol. The women were randomly assigned into 3 groups: group A (136 cases, nylestriol 2 mg/2 wk), group B (97, nylestriol 1 mg/2 wk) and group C (50, placebo/2wk). LDL-C decreased and HDL-C increased after 3 months of medication (P < 0.05), but TC and TG not significantly changed in any group (P > 0.05). No changes of lipids were found in group C (P > 0.05). Serum ALP, Ca/Cr and Hpr/Cr in fasting urine decreased in 3 months in both group A and B (P < 0.05), but not in group C (P > 0.05). Forearm bone mineral content loss was restrained in groups A and B (P > 0.05), but decreased markedly in group C (P < 0.01). The Kupperman index scores decreased by about 50% after 3 months and 80% in 12 months in groups A and B. Nylestriol induced mild stimulatory effect on the uterine endometrium, and addition of 6 mg of provera daily for 7-10 days every 6 months is recommended. Nylestriol exhibited no obvious effect on the breast. This study demonstrated that nylestriol can be used as an effective and acceptable estrogen replacement therapy for postmenopausal women.
Aged↗
[Study on degradation of phenols in water].
The degradation of phenols in water and the effects of microbiolism, pH and dissolved oxygen (DO) on the degradation were investigated. The results showed that the degradation of phenols in water was mainly that of biochemistry, which depends on the existence of microbiolism. The most suitable pH for the degradation was 6 to 9, and no effects of DO on it were found. The accustomization of microbiolism with phenols would accelerate the degradation.
Hydrogen-Ion Concentration↗
[Cloning of beta-amylase gene from B. substitute and its expression in E. coli].
The gene coding for beta-amylase with raw starch-digestion ability was isolated from B. substitute R2 which was selected in this lab. The procedure used in this screening was developed in this work by the method named nutrition-restriction. The DNA fragment containing the beta-amylase gene was 5.25 kb in length. There was no difference in enzymological properties between the beta-amylase produced by the gene-donor strain and the expression product of E. coli. The yield of the cloned beta-amylase was over 500 IU/ml in our laboratory culture condition, the RDA value was 57%, and all of this enzyme were found to be secreted into medium.
Bacillus subtilis↗
[The clinical use of steady-state flash visual evoked potentials].
The authors applied 30Hz flash stimuli to record steady-state flash visual evoked potentials (FVEP) and extracted the amplitudes and phases of the first and second harmonics as the characteristic value by discrete Fourier transform (DFT). 46 normal controls (89 eyes) and 78 patients (109 eyes) were detected and analysed by this method. The result showed that the characteristic values of the normal controls are significantly different in three age groups and showed the positive in 35 eyes with the optic never diseases (82.9%), 25 eyes with age-related macular degeneration (92%), and 9 eyes with retinal detachment involved macular (100%). It indicates the method is a sensitive index to evaluate the macular visual function. After preliminary observation, the visual acuities of postoperation were found above 0.4 in cataracts (28 eyes) or opacities (12 eyes) if preoperative FVEP were normal and non-complicated, or less than 0.4 if preoperative FVEP were abnormal. This suggests the method is one of the effective index to detect the postoperative vision of the media opacities. The advantages, disadvantages and the clinical applications were discussed.
Adolescent↗
[Electroacupuncture enhances enkephalin mRNA expression in the spinal cord and medulla, an in situ hybridization study].
Previous studies in this laboratory have shown that electroacupuncture (EA) accelerated the release of enkephalin in the spinal cord. The present study was undertaken to investigate the effect of EA stimulation on the expression of preproenkephalin (PPE) mRNA in the rat spinal cord and medulla by in situ hybridization histochemical technique. Animals were administrated with 2 Hz EA stimulation (1-2-3 mA, 30 min) applied at acupoints sanyingjiao and zusanli of one hind leg. The rats were perfused 24 h after EA, and quantitative changes of PPE-mRNA expression were determined by emulsion autoradiography. EA stimulation was found to increase the number of neurons expressing PPE-mRNA in spinal cord and medulla. Increased expression of PPE-mRNA was more marked in ipsilateral dorsal horn of spinal cord (especially in laminae III-IV and contralateral ventromedial medulla (especially in the lateral paragigantocellular reticular nucleus). The results provide evidence in support of the enkephalinergic hypothesis of acupuncture analgesia. It is suggested that increased biosynthesis of enkephalin precursor would help to compensate for the loss of tissue storage of enkephalin during the period of EA stimulation.
Animals↗
[Study on health services needs and affecting factors of childbearing-age women of Jingsong Community in Beijing].
A household health interview survey was conducted in 1991 to study the special health problems, health care needs and affecting factors of child bearing-age women. 624 women were randomly sampled in Jingsong Community, Beijing. The results showed that two-week prevalence rate was 20.2 percent, the morbidity rate of chronic diseases was 25.3 percent. These two indexes were higher than the average level of Beijing's population. The medical care needs were great, but utilization of available services was inadequate. The common diseases and woman's diseases were still the major diseases. Preventive health service needs, such as premarriage counseling, postnatal care, women suffer, regular check-up and treatment of woman's diseases, family planning services etc., were not satisfactorily met. The results of the single and multiple variable analysis indicated that the health care needs were mainly affected by age, marital status, education, occupation, system of medical care insurance and position in family. Incidence of gynecopathy was associated with age of the first marriage, number of times of induced abortion etc.. Proposals on improving women's health care in urban community were also put forward in the paper.
Aged↗