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Biomedical subjects

X Ling

Publications and source records attributed to X Ling.

At least 37 records · Page 2Linked to original sources
PubMed1999

Neuronal ERCC6 mRNA expression in rat brain induced by a transient focal cerebral ischemia.

AIM: To study whether the excision repair cross-complementing group 6 (ERCC6) is involved in the neuronal pathophysiological process following cerebral ischemia-reperfusion injury. METHODS: A transient middle cerebral artery occlusion (MCAO) was used to induce cerebral ischemia-reperfusion injury in rat brain. Northern blot was used to check a specific signal for oligonucleotide probe. The expression of ERCC6 mRNA in the rat brain was observed by in situ hybridization. The specific cellular distribution of ERCC6 mRNA in the neuron or glia of the rat brain was analyzed by double staining combined with confocal laser scanning microscopic analysis. RESULT: The expression of ERCC6 mRNA in the penumbra area increased following ischemia and reperfusion with a time-dependent manner. ERCC6 was expressed on d 2, reached peak values on d 3, and kept high level even on d 14 of reperfusion following ischemia. Number of ERCC6 mRNA expressive cell in the penumbra area on d 1, d 2, d 3, d 7, d 14 of reperfusion following ischemia were (0 +/- 0), (253 +/- 56), (816 +/- 355), (341 +/- 185), (128 +/- 95) x 10(6) cells/m2, respectively. Confocal microscopic analysis showed that ERCC6 mRNA coexpressed with phosphopyruvate hydratase in the neurons and with glial fibrillary acidic protein (GFAP) in a few proliferation astrocyte glia. CONCLUSION: The expression of transcription-repair coupling factor ERCC6 mRNA in the neuron and glia was induced by ischemia-reperfusion injury.

Animals↗
PubMed1999

Protective effect of melatonin on injuried cerebral neurons is associated with bcl-2 protein over-expression.

AIM: To study the protective effect of melatonin against neuronal injury and the possible roles of alteration in the expression of bcl-2 and bax following brain ischemia. METHODS: Brain ischemia was induced by left middle cerebral artery occlusion (MCAO) for 60 min in rats. Brain damage was evaluated by the infarct area and the neuronal cell counting. The expression of bcl-2 and bax was analyzed by immunohistochemical method. RESULTS: Melatonin decreased the infarct area and prevented the neuronal death after 24-h reperfusion following 1-h MCAO. Melatonin given before the ischemia enhanced the expression of bcl-2 in the penumbra area and had no significant effect on the expression of bax. CONCLUSION: Melatonin effectively attenuated ischemic brain injury and increased the expression of neuronal bcl-2 in the ischemic brain, indicating that the protective effect of melatonin was associated with up-regulation of bcl-2 in ischemia-induced neuronal death.

Animals↗
PubMed1999

[Diagnostic value of human cytomegalovirus late-mRNA detection for intrauterine active human cytomegalovirus infection].

OBJECTIVE: To study diagnostic value of late-mRNA detection for intrauterine active human cytomegalovirus (HCMV) infection. METHODS: The HCMV late-mRNA in peripheral blood of the pregnant women with HCMV-IgM positive and their fetal appendages (such as chorionic villi, amniotic fluid, umbilical blood and placenta) were detected by reverse transcription polymerase chain reaction(RT-PCR). RESULTS: The late-mRNA was detected in 23 out of 42 HCMV-IgM positive pregnant cases, with the 54.3% of corresponding rate between the results of HCMV-IgM and HCMV late-mRNA. 7 samples out of 13 fetal appendages from m-RNA positive mothers were late-mRNA positive, while in 12 mothers with late-mRNA negative group only one fetal sample was late-mRNA positive, Between two groups there was significant difference in mother-fetus transmission rate. CONCLUSIONS: The positive result of HCMV-IgM can not accurately reflect HCMV activity at the time being detected, which is closely related to the mother-fetus transmission rate. As a symbol of active HCMV infection, late-mRNA can not only reflect the mother-fetus transmission rate during active HCMV infection correctly, but also provide some information about activity of the HCMV in fetal tissue, It also has a great value in prediction for prognosis of infectious fetuses.

Cytomegalovirus↗
PubMed1999

[Study on the human serums by absorption spectra].

The absorption spectra of normal human and cancer patient serums were measured, and those of human serum after adding some cancer cells were also measured. The results showed some difference in absorbance among the three kinds of serums. Some useful results were obtained.

Humans↗
PubMed1998

Genetic vaccination-induced immune responses to the human immunodeficiency virus protein Rev: emergence of the interleukin 2-producing helper T lymphocyte.

Rev M10 is a trans-dominant negative inhibitor of HIV replication. Hence, stable transduction of CD4+ T cells with Rev M10 represents a novel gene therapy aimed at inhibiting HIV replication within these cells, thereby slowing the progression of AIDS. However, the immune system may recognize Rev M10 as foreign and target transduced cells for elimination. In the current study, mice were genetically immunized with a plasmid encoding Rev M10, to (1) identify immune parameters that may be induced by Rev M10 gene transfer, (2) determine the impact of repeated introduction of the Rev M10-encoding plasmid on the immune response to the transgene product, and (3) determine if cotransfection with a plasmid encoding TGFbeta1 would suppress the response. Kinetic studies revealed that Rev-specific IL-2-producing helper T lymphocytes (HTLs) appeared following the second genetic immunization, peaked after the third, and persisted at peak levels for at least 6 weeks. Rev-specific HTLs were CD4+, and the development of these cells was ablated by cotransfection with TGFbeta1. Other cytokines were not readily detectable when immune splenocytes were restimulated with Rev in vitro, and Rev-specific IgG antibodies were not present in the sera of these mice. To our knowledge, this represents the first report that genetic immunization with Rev M10 induces an immune response that is dominated by IL-2-producing HTLs. Further, this study demonstrates the potential utility of introducing immunosuppressive genes as a means to control the immune response to foreign transgene products.

Animals↗
PubMed1998

A highly active microsomal glutathione transferase from frog (Xenopus laevis) liver that is not activated by N-ethylmaleimide.

Microsomal glutathione transferase has hitherto only been purified from mammalian species. N-ethylmaleimide and trypsin activation (discriminating features of this enzyme) has only been observed in microsomes from mammals. In this paper we describe the first isolation and characterization of a non-mammalian microsomal glutathione transferase from frog (Xenopus laevis) liver. This protein has a molecular weight similar to that of the mammalian enzyme (approximately 17 kDa), but cannot be activated by N-ethylmaleimide or trypsin. In fact the enzyme is rapidly inactivated by this sulfhydryl reagent and protease. It thus appears that N-ethylmaleimide activation is not an obligatory property of microsomal glutathione transferase. The frog liver microsomal glutathione transferase has one of the highest specific activities towards the second substrate 1-chloro-2,4-dinitrobenzene (CDNB) (200 mumol/min mg) obtained with any glutathione transferase and accounts for the high activity found in frog liver microsomes. The kcat/K(m) for glutathione and CDNB are 0.017 and 1.1 x 10(6) M-1 s-1, respectively. The enzyme also functions as a glutathione peroxidase (dilinoleoyl phosphatidylcholine hydroperoxide is reduced (5.2 mumol/min mg)). It is now evident that a highly active microsomal glutathione transferase, with a molecular weight similar to that of the mammalian enzymes also exists in a non-mammal species.

Animals↗
PubMed1998

The effect of the level of aggression in the first grade classroom on the course and malleability of aggressive behavior into middle school.

This paper is on the influences of the classroom context on the course and malleability of aggressive behavior from entrance into first grade through the transition into middle school. Nineteen public elementary schools participated in developmental epidemiologically based preventive trials in first and second grades, one of which was directed at reducing aggressive, disruptive behavior. At the start of first grade, schools and teachers were randomly assigned to intervention or control conditions. Children within each school were assigned sequentially to classrooms from alphabetized lists, followed by checking to insure balanced assignment based on kindergarten behavior. Despite these procedures, by the end of first quarter, classrooms within schools differed markedly in levels of aggressive behavior. Children were followed through sixth grade, where their aggressive behavior was rated by middle school teachers. Strong interactive effects were found on the risk of being highly aggressive in middle school between the level of aggressive behavior in the first grade classrooms and each boy's own level of aggressive, disruptive behavior in first grade. The more aggressive first grade boys who were in higher aggressive first grade classrooms were at markedly increased risk, compared both to the median first grade boys, and compared to aggressive males in lower aggressive first grade classrooms. Boys were already behaving more aggressively than girls in first grade; and no similar classroom aggression effect was found among girls, although girls' own aggressive behavior did place them at increased risk. The preventive intervention effect, already reported elsewhere to reduce aggressive behavior among the more aggressive males, appeared to do so by reducing high levels of classroom aggression. First grade males' own poverty level was associated with higher risk of being more aggressive, disruptive in first grade, and thereby increased their vulnerability to classroom level of aggression. Both boys and girls in schools in poor communities were at increased risk of being highly aggressive in middle school regardless of their levels of aggressive behavior in first grade. These results are discussed in terms of life course/social field theory as applied to the role of contextual influences on the development and etiology of severe aggressive behavior.

Adolescent↗
PubMed1998

[The expression of nm23-H1 and p53 protein in nasopharyngeal carcinoma].

UNLABELLED: To evaluate the role of nm23-H1 and p53 protein expression in Nasopharyngeal Carcinoma (NPC), the S-P immunohistochemical method was used to detect the expression of nm23-H1 and p53 protein in 125 cases of NPC. RESULTS: The positive expression for nm23-H1 and p53 were 50.4%(63/125), 90.4%(113/125), respectively nm23-H1 expression in the NPC with cervical lymph node metastasis and without cervical lymph node metastasis were 27.9%(17/61) and 71.9%(46/64), respectively (P < 0.001). CONCLUSION: 1. Mutations of p53 may play a role in carcinogenesis of NPC. 2. The difference between the NPC with cervical lymph node metastasis and without cervical lymph node metastasis for nm23-H1 expression was significant. The nm23-H1 gene may play a role in antimetastasis of NPC.

Adult↗
PubMed1998

Immunohistochemical distribution and subcellular localization of three distinct specific molecular structures of advanced glycation end products in human tissues.

Using three mouse anti-human monoclonal antibodies for advanced glycation end products (AGEs), 6D12, 1F6, and 2A2, we examined the immunohistochemical distribution and localization of AGEs in various organs and tissues obtained from nondiabetic autopsy or biopsy cases (men and women, 41 to 86 years of age). 6D12 recognizes Nepsilon-(carboxymethyl)lysine (CML), a nonfluorescent and non-cross-linked AGE structure, and 1F6 recognizes fluorolink, a fluorescent and cross-linked AGE structure. The epitope of 2A2 is unknown but is different from that of CML and fluorolink or other known AGE structures such as pyrraline, pentosidine, and crosslines. Immunohistochemistry with these monoclonal antibodies revealed the intra- and extracellular accumulation of AGEs in these organs and tissues. By double immunohistochemical staining with two of the three monoclonal antibodies in different combinations, positive reaction products for all three monoclonal antibodies were demonstrated in macrophages widely distributed in various organs and tissues; endothelial cells of endocardium, arteries, veins, and blood capillaries; mesenchymal cells; epithelial or parenchymal cells; blood cells; and extracellular matrix. This result indicates that these three different AGE-specific molecules are formed intracellularly and extracellularly. In some cell types, however, one or two of these specific molecules were not always found together, suggesting that the molecular structures of AGEs and their formation are heterogeneous. Immunoelectron microscopy demonstrated the localization of AGE-labeled immunogold particles in the nuclei, nuclear envelope, mitochondria, endoplasmic reticula, Golgi complexes, endocytic vesicles, lysosomal vacuoles or granules, secretory granules, cytosol, and cell membranes, as well as in the extracellular matrix. In addition, the double histochemical staining method for ceroid/lipofuscin and immunohistochemistry for AGEs demonstrated intralysosomal formation and accumulation of AGEs in ceroid/lipofuscin pigments. These results suggest that the extracellularly produced AGEs are taken up by receptors into the cells and accumulate in secondary lysosomes and that AGEs are formed intranuclearly and/or intracellularly, probably via different metabolic pathways.

Adult↗
PubMed1998

Requirements for enhanced transgene expression by untranslated sequences from the human cytomegalovirus immediate-early gene.

BACKGROUND: The cytomegalovirus immediate early (CMV IE) promoter has been widely used for heterologous expression. Further enhancements of gene expression from this potent promoter may allow for the development of improved gene transfer strategies. We aimed to determine whether inclusion of the first exon (5' untranslated) and first intron of the CMV IE gene would increase heterologous transgene expression in primary target cells and to determine the sequences required for any observed increases. MATERIALS AND METHODS: Comparisons of reporter gene expression were made following transient transfection of vascular smooth muscle cells (VSMCs) with plasmids containing the first exon and intron from the CMV IE gene or deletional mutations. Comparisons were also made using a heterologous promoter (RSV). RESULTS: Gene expression from the CMV IE promoter was increased 5.7-fold in VSMC with the inclusion of the first exon and intron. Similar increases were seen with other target cells and from the heterologous RSV promoter. This increase was associated with an increase in steady-state mRNA. Deletion analyses demonstrated that the enhancement was dependent on the presence of the 5' portion of the first exon while deletion of large segments within the intron was associated with similar levels of expression compared with the parental plasmid. CONCLUSIONS: Inclusion of the first exon and intron from the CMV IE gene increases expression from the CMV IE promoter. This enhancement is seen with the heterologous RSV promoter and is associated with an increase in steady-state mRNA. Deletion analyses suggest that this enhancement is associated with inclusion of sequences within the 5' portion of the first exon and inclusion of an intron.

Animals↗
PubMed1997

Combination gene transfer to potentiate tumor regression.

Recent efforts to treat malignancy using gene transfer have met with varying degrees of success. In this paper, we report the results of studies using two recombinant adenoviral vectors to examine the efficacy of combination gene transfer to cause tumor regression in vivo. One of these vectors encodes the murine MHC class I gene, H-2Kb (ADV-Kb), which induces an immune response that stimulates tumor regression. The second vector encodes the human p21 cyclin dependent kinase inhibitor (ADV-p21). This gene product arrests cell cycle progression and prevents proliferation of tumor cells. Both vectors were tested in a murine model in vivo for antitumor effect. As previously shown, a significant reduction of tumor size was observed with each vector. Combination treatment, in which both vectors were administered, resulted in a trend toward a reduced tumor growth greater than with either vector alone. In order to characterize the mechanism of tumor regression, cytolytic T lymphocyte (CTL) assays against the allogeneic molecule, H-2Kb, were performed. Mice treated with ADV-Kb showed specific CTL activity against the H-2Kb molecule, demonstrating that the immune response against the H-2Kb gene product involved in tumor regression was potentiated by expression of the p21 gene which affects cell cycle progression.

Adenoviridae↗
PubMed1997

Consequences of foot binding among older women in Beijing, China.

OBJECTIVES: This study examined the prevalence and consequences of foot binding in older Chinese women. METHODS: Women older than 70 years in Beijing, China, were assessed for bound feet, falls, functional status, and bone density. RESULTS: Thirty-eight percent of women aged 80 years and older and 18% of women aged 70 through 79 years had bound-foot deformities. Women with bound feet were more likely to fall, less able to squat, and less able to stand up from a chair without assistance than women with normal feet. They also had 14.3% less functional reach (a test of balance) and 5.1% lower hip bone density. CONCLUSIONS: Foot binding has caused substantial disability that is still evident in many elderly Chinese women.

Accidental Falls↗
PubMed1997

[A study of human papillomavirus infection during pregnancy and transmission of virus to fetus].

To study the human papillomavirus (HPV) infection during pregnancy and transmission of virus to fetus, samples such as, cervical secretion, peripheral blood, amniotic fluid, neonatal umbilical blood from 96 women with normal pregnancy were screened for HPV DNA by polymerase chain reaction (PCR), and HPV DNA in condyloma acuminata tissues, amniotic fluid of 31 pregnant women were detected by PCR as well. The results showed HPV DNA positive rate of condyloma acuminata tissues was 92.32%, of cervical secretion in normal pregnant group, was 35.71%, of peripheral blood was 57.69%. The HPV DNA maternal-fetus transmission rate was 44.44%, the transmission rate via placenta was 60%. It is concluded that HPV DNA can be found not only in condyloma acuminata tissues, but also in genital tract, peripheral blood of pregnant women, Besides the transmission route of genital tract, there is also the blood-placenta route.

Adult↗
PubMed1997

[Average length of spontaneous labor in Chinese primigravidas].

OBJECTIVE: To determine if labor duration is affected by ethnicity, we measured the average length of normal spontaneous labor in recently immigrated Chinese primigravidas and compared our findings to reference primigravida populations of differing ethnicity. MATERIALS AND METHODS: In this descriptive, retrospective study of 1,006 recently immigrated low-risk Chinese primigravidas delivering singleton, vertex, term infants (37-42 weeks gestation, inclusively) without conduction anesthesia or oxytocin, the length of first-, second-, and third-stage labor, maternal age, gestational age, and infant weight was measured and compared to labor lengths previously reported for women of differing ethnicity. RESULTS: Mean first stage labor duration was 326 minutes (SD +/- 185 min, range 25-1640 min), mean second stage labor duration was 52 minutes (SD +/- 42 min, range 2-450 min), and a mean third stage labor duration was 4.6 min (SD +/- 4.5 min, range 1-62 min). Interquartile range (IQR)/median for first-, second-, and third-stage labor was 225 min/300 min, 50 min/40 min, and 3 min/3 min respectively. Weak correlations were observed between first- and second-stage labor lengths, and second- and third-stage labor lengths. Average birth weight was 3250 g (SD +/- 376 g, range 2280-4660 g). Chinese parturients showed a significantly shorter duration of first-stage (P < 0.0001) when compared to parity-matched patients of differing ethnicity. Second-stage labor in Chinese parturients was also shorter, but did not differ significantly (P = 0.185) from previously reported non-Asian controls. CONCLUSION: When compared to previously collected data from non-Chinese women, clinically significant differences in first-stage labor lengths were measured in our study population. While second-stage labor durations were also shorter, the difference was not significant. Labor management should be individualized to account for these differences, and previous reports attempting to show equivalency of labor progress regardless of ethnicity warrant reinterpretation given these findings.

Asian People↗
PubMed1996

All four core histone N-termini contain sequences required for the repression of basal transcription in yeast.

Nucleosomes prevent the recognition of TATA promoter elements by the basal transcriptional machinery in the absence of induction. However, while Saccharomyces cerevisiae histones H3 and H4 contain N-terminal regions involved in the activation and repression of GAL1 and in the expression of heterochromatin-like regions, the sequences involved in repressing basal transcription have not yet been identified. Here, we describe the mapping of new N-terminal domains, in all four core histones (H2A, H2B, H3 and H4), required for the repression of basal, uninduced transcription. Basal transcription was monitored by the use of a GAL1 promoter-URA3 reporter construct whose uninduced activity can be detected through cellular sensitivity to the drug, 5-fluoroorotic acid. We have found for each histone that the N-terminal sequences repressing basal activity are in a short region adjacent to the structured alpha-helical core. Analysis of minichromosome DNA topology demonstrates that the basal domains are required for the proper folding of DNA around the chromosomal particle. Deletion of the basal domain at each histone significantly decreases plasmid superhelical density, which probably reflects a release of DNA from the constraints of the nucleosome into the linker region. This provides a means by which basal factors may recognize otherwise repressed regulatory elements.

Acetylation↗
PubMed1996

Yeast histone H3 and H4 amino termini are important for nucleosome assembly in vivo and in vitro: redundant and position-independent functions in assembly but not in gene regulation.

The hydrophilic amino-terminal sequences of histones H3 and H4 extend from the highly structured nucleosome core. Here we examine the importance of the amino termini and their position in the nucleosome with regard to both nucleosome assembly and gene regulation. Despite previous conclusions based on nonphysiological nucleosome reconstitution experiments, we find that the histone amino termini are important for nucleosome assembly in vivo and in vitro. Deletion of both tails, a lethal event, alters micrococcal nuclease-generated nucleosomal ladders, plasmid superhelicity in whole cells, and nucleosome assembly in cell extracts. The H3 and H4 amino-terminal tails have redundant functions in this regard because the presence of either tail allows assembly and cellular viability. Moreover, the tails need not be attached to their native carboxy-terminal core. Their exchange re-establishes both cellular viability and nucleosome assembly. In contrast, the regulation of GAL1 and the silent mating loci by the H3 and H4 tails is highly disrupted by exchange of the histone amino termini.

Base Sequence↗
PubMed1996

Computer simulation of epicardial potentials using a heart-torso model with realistic geometry.

Previous cardiac simulation studies have focused on simulating the activation isochrones and subsequently the body surface potentials. Epicardial potentials, which are important for clinical application as well as for electrocardiographic inverse problems studies, however, have usually been neglected. This paper describes a procedure of simulating epicardial potentials using a microcomputer-based heart-torso model with realistic geometry. Our heart model developed earlier is composed of approximately 65,000 cell units which are arranged in a cubic close-packed structure. An action potential waveform with variable in duration is assigned to each unit. The heart model, together with the epicardial surface model constructed recently, are mounted in an inhomogeneous human torso model. Electric dipoles, which are proportional to the spatial gradient of the action potential, are generated in all the cell units. These dipoles give rise to a potential distribution on the epicardial surface, which is calculated by means of the boundary element method. The simulated epicardial potential maps during a normal heart beat and in a preexcited beat to mimic Wolff-Parkinson-White (WPW) syndrome are in close agreement with those reported in the literature.

Action Potentials↗