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Biomedical subjects

H Shen

Publications and source records attributed to H Shen.

At least 127 records · Page 7Linked to original sources
PubMed2001

[Determination of trace as in health-giving drink by AA-670 atomic absorption spectrophotometry attached VA-90 atomization].

A new method has been developed for the determination of trace metal As in health-giving drink by AA-670 atomic absorption spectrophotometry attached VA-90 atomization. The method is convenient to determine element in water. The results show that the method has good precision and accuracy. The detection limit is 2 ng.L-1 for As. The relative standard deviation is 5.4%-6.1%, and the rates of recovery is 87.5%-115%. This method has been applied to the determination of health-giving drink with satisfactory results.

Arsenic↗
PubMed2001

[Determination of nickel in artificial cream by flame atomic absorption spectrometry].

This paper describes a new method for the determination of nickel in artificial cream by flame atomic absorption spectrometry. Compared with the others, the process of sample treatment by HNO3-H2SO4 is simple, and the operation is easy. The results show that the method offers good precision and accuracy. The relative standard deviation is 3.04% and the rate of recovery is 97.7%.

Food Contamination↗
PubMed2000

Polymorphisms of the DNA repair gene XRCC1 and risk of gastric cancer in a Chinese population.

Gastric cancer remains the leading cause of cancer death in China and other countries in eastern Asia. Studies of gastric cancer have revealed that it is a disease of complex etiology involving dietary, infectious, environmental, occupational and genetic factors. DNA repair capacity has been suggested as a genetic factor contributing to variation in susceptibility to cancer. In the present study, we described an association between 2 polymorphisms of the DNA repair gene XRCC1 and risk of gastric cancer in a Chinese population. We used a polymerase chain reaction-based assay to detect Pvu II and Nci I restriction fragment length polymorphisms (XRCC1 26304 C-->T and XRCC1 28152 G-->A, respectively) in 188 patients with gastric cancer and 166 healthy controls. The XRCC1 26304 T allele (194Trp) frequency (34.6%) was higher and the XRCC1 28152 A allele (399Gln) frequency (25.6%) was lower in healthy Chinese controls than previously reported healthy U.S. Caucasian controls (7.2% and 34.1%, respectively). Multivariate logistic regression analysis revealed that the putative high-risk genotypes XRCC1 26304 CC and XRCC1 28152 GA/AA were associated with a non-significant increased risk for gastric cancer (adjusted odds ratio [OR]=1.45, 95% confidence interval [CI]= 0.93-2.25 and OR=1.53, 95% CI= 0.98-2.39, respectively) compared with other genotypes. However, the XRCC1 26304 CC genotype was associated with a significantly increased risk for gastric cardia cancer (adjusted OR=1.86, 95% CI=1.09-3.20). Individuals with both putative high-risk genotypes (CC and GA/AA) had a significantly higher risk (adjusted OR=1.73, 95% CI=1.12-2.69), particularly for gastric cardia cancer (adjusted OR=2.18, 95% CI=1.21-3.94) than individuals with other genotypes. These findings support the hypothesis that these 2 XRCC1 variants may contribute to the risk of developing gastric cancer, particularly gastric cardia cancer.

Adult↗
PubMed2000

Two site contact of elongating transcripts to phage T7 RNA polymerase at C-terminal regions.

A series of active elongation complexes of the phage T7 RNA polymerase were obtained through stepwise walking of the polymerase along an immobilized DNA template. Transcripts were radiolabeled at the 16th to 18th residues, and a photocross-linkable 4-thio-UMP was separately incorporated at the 22nd, 24th, 32nd, and 38th residues. Such complexes (up to 51 nucleotides) produced by the incorporation of one nucleotide at a time were isolated and individually subjected to long wave UV cross-linking. Only when the cross-linker was positioned at the 3'-end (-1) of the elongating RNA and 8 nucleotides upstream (-9), was the RNA substantially cross-linked to the polymerase, regardless of how far it was from the 5'-end of the transcripts. Linkage of the 3'-end residue was mapped to the Thr(636)-Met(666) region, which contains nucleotide-binding sites. The -9 residue was cross-linked to the Ala(724)-Met(750) region rather than to the N-terminal region. These two contacts were maintained throughout the elongation complexes and reveal a route of nascent RNA through the T7 RNA polymerase in elongation complexes.

Binding Sites↗
PubMed2000

Controlling human polymorphonuclear leukocytes motility using microfabrication technology.

We describe a new approach for controlling cell motility on a material surface. Transparent, photosensitive polyimide materials were used to fabricate physical structures on glass; cell motility was then followed over time using optical microscopy. Arrays of pillars and holes with 2 micron square, 4-microm height (or depth) separated by 10 microm were successfully patterned using photolithography. Neutrophils attached and spread on the smooth glass surface and surfaces with pillars. In contrast, cells were rounded and did not adhere to either smooth polyimide film or films with holes. The migration of neutrophils was much faster on holes than on polyimide surface, but it was significantly slower on pillars than on glass. These results suggest that physical patterning may be an effective tool to manipulate cell migration in the design of biomaterials for tissue engineering.

Biocompatible Materials↗
PubMed2000

Dual role of glutathione in selenite-induced oxidative stress and apoptosis in human hepatoma cells.

It is well known that glutathione, the major intracellular antioxidant, is closely involved in the metabolism and bioactivity of selenium. In the present study, glutathione was demonstrated to play a dual role on selenite (Se)-induced oxidative stress and apoptosis in human hepatoma HepG(2) cells. The experiment was carried out in two different modes to modulate intracellular reduced glutathione (GSH) content. In Mode A (pretreatment), cells were pretreated with N-acetylcysteine (NAC), buthionine sulfoximine (BSO), or GSH prior to Se exposure. In Mode B (simultaneous treatment), cells were treated with Se and NAC, BSO, or GSH simultaneously. It was found that Se-induced oxidative stress and apoptosis are closely related to the intracellular level of GSH. Both the increase and depletion of GSH content significantly enhanced Se-induced oxidative stress and apoptosis in HepG(2) cells. Results from this study clearly demonstrated that GSH has a dual role in the effects of Se on cancer cells: (i) GSH acts as a pro-oxidant, facilitating Se-induced oxidative stress, and (ii) GSH acts as an antioxidant, protecting against Se-induced oxidative stress and apoptosis. Understanding such a unique association between GSH and Se may help to explain the controversy in the literature over the complex relationship between selenium and glutathione, and ultimately the capability of selenium to prevent cancer.

Acetylcysteine↗
PubMed2000

Hematopoietic stem cell quiescence maintained by p21cip1/waf1.

Relative quiescence is a defining characteristic of hematopoietic stem cells, while their progeny have dramatic proliferative ability and inexorably move toward terminal differentiation. The quiescence of stem cells has been conjectured to be of critical biologic importance in protecting the stem cell compartment, which we directly assessed using mice engineered to be deficient in the G1 checkpoint regulator, cyclin-dependent kinase inhibitor, p21cip1/waf1 (p21). In the absence of p21, hematopoietic stem cell proliferation and absolute number were increased under normal homeostatic conditions. Exposing the animals to cell cycle-specific myelotoxic injury resulted in premature death due to hematopoietic cell depletion. Further, self-renewal of primitive cells was impaired in serially transplanted bone marrow from p21-/- mice, leading to hematopoietic failure. Therefore, p21 is the molecular switch governing the entry of stem cells into the cell cycle, and in its absence, increased cell cycling leads to stem cell exhaustion. Under conditions of stress, restricted cell cycling is crucial to prevent premature stem cell depletion and hematopoietic death.

Animals↗
PubMed2000

Polysialylated neural cell adhesion molecule modulates photic signaling in the mouse suprachiasmatic nucleus.

Polysialic acid (PSA), a sialic acid polymer that regulates plasticity and cell-cell interactions in neural tissues, is expressed in the mammalian circadian clock located in the suprachiasmatic nucleus (SCN). In vivo enzymatic removal of PSA from the mouse SCN significantly impaired both the photic induction of Fos protein in SCN cells and light-induced phase-resetting of the circadian locomotor activity rhythm. Genetic deletion of PSA and it's neural cell adhesion molecule (NCAM) carrier correspondingly attenuated light-induced circadian phase-shifting. Comparison of PSA levels between young and old mice revealed a large aging-related reduction in SCN PSA content that accompanies the diminished capacity for circadian photic response reported in old rodents. Collectively these data support the contention that PSA modulates photic signaling in the SCN, and that normal reductions in the cell surface molecule contribute to aging-related deficits in SCN circadian clock function.

Animals↗
PubMed2000

Detection of oxidative DNA damage in human sperm and its association with sperm function and male infertility.

The expanding research interest in the last two decades on reactive oxygen species (ROS), oxidative stress, and male infertility has led to the development of various techniques for evaluating oxidative DNA damage in human spermatozoa. Measurement of 8-hydroxydeoxyguanosine (8-OHdG) offers a specific and quantitative biomarker on the extent of oxidative DNA damage caused by ROS in human sperm. The close correlations of 8-OHdG level with male fertility, sperm function and routine seminal parameters indicate the potential diagnostic value of this technique in clinical applications. On the other hand, single cell gel electrophoresis (SCGE or comet assay) and terminal deoxynucleotidyl transferase (TdT) mediated dUTP nick end labeling (TUNEL) assay have also been demonstrated to be sensitive, and reliable methods for measuring DNA strand breaks in human spermatozoa. As certain technical limitations were inherent in each of these tests, it is believed that a combination of these assays will offer more comprehensive information for a better understanding of oxidative DNA damage and its biological significance in sperm function and male infertility.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2000

Cytokine responses to Der p 1 and Der p 7: house dust mite allergens with different IgE-binding activities.

BACKGROUND: There is very limited information comparing T-cell responses to different house dust mite (HDM) allergens even though T cells are essential in the initiation and regulation of immunoglobulin (Ig) E synthesis and eosinophilia. OBJECTIVE: To compare the level of T-cell proliferation and cytokine production to the group 1 and group 7 HDM allergens which are known to have different IgE-binding capabilities. METHODS: Freshly isolated peripheral blood mononuclear cells (PBMC) from HDM-allergic and HDM-nonallergic donors were stimulated with the group 1 and group 7 allergens of Dermatophagoides pteronyssinus and the level of proliferation as well as IL-5 and IFNgamma production were measured. RESULTS: The proliferative and IL-5 production to the group 1 and group 7 allergens were equivalent despite the group 7 allergen's lower frequency of IgE-binding. However more IFNgamma was produced to Der p 7 than to Der p 1, particularly for the nonallergic donors. As expected IL-5 production was much higher for PBMC from the allergic donors than for cells from nonallergics; however, there was no difference in the level of T-cell proliferation between the donor groups. CONCLUSION: The relative importance of the individual HDM allergens is normally determined by measuring the frequency of IgE-binding to the allergen in sera from an allergic population. The equivalent increased IL-5 response of PBMC from allergic people to the group 1 and group 7 allergens despite the different IgE-inducing activity indicates that these allergens may be equally capable of contributing to an asthmatic response by inducing eosinophilia.

Adult↗
PubMed2000

SF-36 health survey: tests of data quality, scaling assumptions, and reliability in a community sample of Chinese Americans.

BACKGROUND: Chinese Americans are one of the fastest growing ethnic groups in the United States; however, language and cultural obstacles have challenged health workers and policy makers seeking to understand the health status and needs of this population. OBJECTIVES: This study is the first to use a large-scale probability design to evaluate the 36-item Short-Form Health Survey (SF-36) in a Chinese population (n = 1,501). METHODS: Using the International Quality of Life Assessment Project protocols, we examine summated-rating scaling assumptions, item-internal consistency, item-discriminant validity, and reliability. RESULTS: Similar to previous studies, our tests indicated that the SF-36 generally met minimum psychometric criteria with high reliability and satisfactory scaling success rates for most scales. However, the performance of the vitality and mental health scales was less satisfactory with regard to discriminant validity and scaling success rates. Notably, our results indicate that VT3 and VT4 ("feel worn out" and "tired", respectively) formed a separate "fatigue" cluster more highly correlated with the mental health scale. However, MH4 and MH5 ("downhearted and blue" [reverse coded] and "been a happy person") were more highly correlated with the vitality scale, suggesting that it may be more meaningful to reorganize the vitality and mental health items along the dimensions of well-being and distress. CONCLUSIONS: These results are interpreted within a cultural framework; however, additional work is needed to better understand the relationship between vitality and mental health for Chinese Americans.

Adolescent↗
PubMed2000

Reduced xenograft rejection in rat striatum after pretransplant photodynamic therapy of murine neural xenografts.

OBJECT: The goal of this study was to develop a method of reducing neural xenograft rejection by pretreating the graft with photodynamic therapy (PDT). METHODS: Xenograft cell suspensions were prepared from fetal mouse mesencephalon, after which they were incubated for 30 minutes with various concentrations of a photosensitizer, verteporfin for injection, and light exposure. The xenograft cell suspensions were injected into the dopamine-depleted striata of 40 hemiparkinsonian rats assigned to different treatment groups. Four weeks after transplantation, xenograft function (determined by methamphetamine-induced rotation) and survival (determined by immunohistochemical staining for murine neurons) were compared. Group 1 animals (xenografts pretreated with 25 ng/ml verteporfin) and Group 3 animals (no verteporfin pretreatment, but daily administration of cyclosporin A) had significantly better xenograft survival and function compared with control animals (no pretreatment with verteporfin). Group 2 animals (xenografts pretreated with 250 ng/ml verteporfin) had no significant improvement. CONCLUSIONS: This work demonstrates improved neural xenograft survival and function when using pretransplant PDT of the graft in a rodent model. The potential benefits of this new therapy are its convenience (one pretransplant treatment) and its compatibility with host immunosuppression.

Analysis of Variance↗
PubMed2000

[DNA polymorphism of Pvu II site in the lipoprotein lipase gene in patients with type 2 diabetes mellitus].

OBJECTIVE: To study the relationship between the lipoprotein lipase(LPL) gene and type 2 diabetes mellitus (DM) and its lipid metabolism. METHODS: PCR-RFLP method was used to determine the DNA polymorphism of 6th intron at LPL gene in 127 DM patients and 125 controls. RESULTS: The allele frequencies in case and control groups were 69.3%, 63.6% for "P+" and 30.7%, 36.4% for "P-", respectively; the frequencies of genotypes were 48.0%, 44.8% for P+/P+, 42.5%, 37. 6% for P+/P- and 9.45%, 17.6% for P-/P-, respectively. There was no significant difference in frequencies of genotypes or alleles between the two groups. The LPL Pvu II polymorphism in Chinese population was similar to that in Japanese population, and was different from that in European and American population. CONCLUSION: The LPL-Pvu II-RFLP in Chinese population is not significantly associated with type 2 diabetes mellitus. The significant difference of Pvu II-RFLP among various races was observed.

Adult↗
PubMed2000

New concepts and methods of standardizing predictive value, accuracy and incorrect diagnostic rate.

OBJECTIVE: To express the value of a diagnostic test under standardized and comparable conditions. STUDY DESIGN: Four new concepts of standardizing positive predictive value (SPPV), standardizing negative predictive value (SNPV), standardizing accuracy (SAc) and standardizing an incorrect diagnostic test were developed. The theoretical positive predictive value (SPPV), theoretical negative predictive value (SNPV), theoretical accuracy (SAc) and theoretical incorrect diagnosis rate (SIDR), which are not affected by a different constituent ratio of disease and nondisease groups and are obtained under the theoretical standard condition that the sample size in the disease group equals that in the nondisease group, were defined. Based on these concepts and the principles and methods of statistics and evaluation of diagnostic tests, corresponding formulas were deduced. RESULTS: The formulas are: SPPV = a(b + d)/[a(b + d) + b(a + c)] = Se/(1 + Se - Sp), SNPV = d(a + c)/[c(b + d) + d(a + c)] = Sp/(1 - Se + Sp), SAc = [a(b + d) + d(a + c)]/[2(a + c)(b + d)] = (Se + Sp)/2, and SIDR = [b(a + c) + c(b + d)]/[2(a + c)(b + d)] = (2 - Se - Sp)/2. Here, a, b, c and d refer to the case numbers of true positives, false positives, false negatives and true negatives; Se and Sp refer, respectively, to sensitivity and specificity. CONCLUSION: SPPV, SNPV, SAc and SIDR are very useful for expressing and evaluating the value of a diagnostic test under standardized and comparable conditions.

Breast Neoplasms↗
PubMed2000

Distribution of alpha1-adrenoceptor subtype proteins in different tissues of neonatal and adult rats.

Distribution of alpha(1)-adrenoceptor (alpha(1)AR) subtype (alpha(1A), alpha(1B), alpha(1D)) proteins in brain, heart, kidney, and liver of 1-week-old rats and in brain, heart, aorta, kidney, liver, vas deferens, prostate, and adrenal glands of adult rats was investigated by Western analysis, using receptor subtype specific polyclonal antibodies. High levels of immunoreactive alpha(1A)AR and alpha(1D)AR in brain and heart and of alpha(1B)AR in liver and heart of neonatal rats were detected. In adult rat tissues, the abundance of alpha(1A)AR protein was most marked in the brain, intermediate in heart, aorta, liver, vas deferens, and adrenals, and minimal in the kidney and prostate; relative to other tissues, the expression of alpha(1B)AR was higher in brain and heart and that of alpha(1D)AR in brain. All the three receptor subtypes increased with age in the brain cortex, whereas the abundance of alpha(1B)AR increased in the heart but decreased in the liver; alpha(1A)AR and alpha(1D)AR in liver, kidney, and heart were not affected by age. It is concluded that alpha(1)AR subtypes are widely expressed in different neonatal and adult rat tissues.

Age Factors↗
PubMed2000

Quantitative chromatics analysis for computer imaging of cytologic subtypes of lung cancer stained by Papanicolaou stain.

OBJECTIVE: To determine the role of quantitative chromatics analysis in the classification of subtypes of lung cancer stained by Papanicolaou stain. STUDY DESIGN: By means of computer image analysis, 60 keratinized squamous carcinoma cells (KSCC), 88 nonkeratinized squamous carcinoma cells (NKSCC) and 150 adenocarcinoma cells (ACC) from lung cancer in sputum smears stained by Papanicolaou stain were analyzed and distinguished based on quantitative colorimetry. The features measured were the content of three primary colors, red (R), green (G) and blue (B) and the coefficients of R, G and B (r, g and b, respectively). Hue, saturation, brightness and gray level were also measured. A stepwise discriminant analysis was carried out. RESULTS: The values of R, G and B and r, g and b, hue and saturation in NKSCC and ACC were significantly different from those of KSCC, and the changes in the three primary colors were more sensitive than those in the gray level. Computer assessment based on three primary color coefficients, hue and saturation yielded accuracy of distinguishing KSCC from NKSCC and KSCC from ACC of 95.2% and 95%, respectively. CONCLUSION: Quantitative analyses of R, G and B and r, g, b and hue and saturation are valuable in distinguishing KSCC from NKSCC and ACC.

Adenocarcinoma↗