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Biomedical subjects

Hong Chen

Publications and source records attributed to Hong Chen.

At least 253 records · Page 14Linked to original sources
PubMed2002

Tumor necrosis factor receptor levels are associated with carotid atherosclerosis.

BACKGROUND AND PURPOSE: Recent evidence suggests that atherosclerosis is an inflammatory condition. Serum levels of inflammatory markers may serve as measures of the severity of atherosclerosis and risk of stroke. We sought to determine whether tumor necrosis factor-alpha (TNF-alpha) and TNF receptor levels are associated with carotid plaque thickness. METHODS: The Northern Manhattan Stroke Study is a community-based study of stroke risk factors. For this cross-sectional analysis, inflammatory marker levels, including TNF-alpha and TNF receptors 1 and 2, were measured by immunoassay in stroke-free community subjects undergoing carotid duplex Doppler ultrasound. Maximal carotid plaque thickness (MCPT) was measured for each subject. Analyses were stratified by age < 70 and > or =70 years. Simple and multiple linear regression analyses were used to calculate the association between marker levels and MCPT. Multiple logistic regression was used to calculate odds ratios and 95% CIs for the association of inflammatory markers with MCPT > or =1.5 mm (>75th percentile), after adjustment for demographic and potential medical confounding factors. RESULTS: The mean age of the 279 subjects was 67.6+/-8.5 years; 49% were men; 63% were Hispanic, 17% black, and 17% white. Mean values for TNF-alpha and its receptors were as follows: TNF-alpha, 1.88+/-3.97 ng/mL; TNF receptor 1, 2.21+/-0.99 ng/mL; and TNF receptor 2, 4.85+/-2.23 ng/mL. Mean MCPT was elevated in those in the highest quartiles compared with lowest quartiles of TNF receptor 1 and 2 (1.24 versus 0.79 mm and 1.23 versus 0.80 mm, respectively). Among those aged < 70 years, TNF receptor 1 and 2 were associated with an increase in MCPT (mean difference=0.36 mm, P=0.01 for TNF receptor 1 and mean difference=0.10 mm, P=0.04 for TNF receptor 2). After adjustment for sex, race-ethnicity, hypertension, diabetes mellitus, LDL cholesterol, smoking, and body mass index, associations remained (mean difference=0.36 mm, P=0.001 for TNF receptor 1 and mean difference=0.09 mm, P=0.051 for TNF receptor 2). There was no association for TNF receptors in those aged > or = 70 years old and no association for TNF-alpha in either age group. Among those aged < 70 years, each unit increase in TNF receptor level increased the odds of the participant's having MCPT > or =1.5 mm (adjusted odds ratio=4.7; 95% CI, 1.7 to 15.4 for TNF receptor 1; odds ratio=1.9; 95% CI, 1.3 to 2.9 for TNF receptor 2). CONCLUSIONS: Relative elevation in TNF receptor levels, but not TNF-alpha, is associated with carotid atherosclerosis among individuals aged < 70 years in this multiethnic, urban population. Chronic subclinical infection or inflammation may account for this association, and modification of these inflammatory pathways may provide a novel approach to stroke prevention.

Age Factors↗
PubMed2002

Regulation of 1,25-dihydroxyvitamin d synthesis by intracellular vitamin d binding protein-1.

Control of 125-dihydroxyvitamin D (1,25-(OH)2D) synthesis is believed to be primarily at the level of expression of the vitamin D-1-hydroxylase (CYP1alpha; CYP1alpha) gene. Once transcribed, generation of product, as catalyzed by 1-hydroxylase, depends upon the availability of various co-factors, molecular oxygen, electrons as well as substrate to the enzyme. Here we provide evidence that the quantity of product 1,25-(OH)2D generated also relies on the presence and level of expression of the intracellular vitamin D binding protein-1 (IDBP-1) and its capacity to promote 24-hydroxylase (CYP24) gene expression. Stable transfection of the IDBP-1 cDNA increased 1,25-(OH)2D synthesis up to 700% (p < 0.001) in cells devoid of 24-hydroxylating potential but only 70% (p = 0.018) in cells in which the CYP24 gene is expressed. IDBP-1-mediated increase in 1,25-(OH)2D production was independent of any change in CYP1alpha expression but highly dependent on the ability of exogenously-added or endogenously-synthesized 1,25-(OH)2D to stimulate CYP24 gene expression. These data suggest that IDBP-1 is capable of controlling 1,25-(OH)2D production by modulating the delivery of 1) substrate 25-OHD to in the mitochondrial CYP1alpha gene product and 2) CYP1alpha product 1,25-(OH)2D to the vitamin D receptor for upregulation of expression of the catabolic CYP24 gene.

Animals↗
PubMed2002

Population dynamics of apple maggot (Diptera: Tephritidae) in south central Pennsylvania.

The apple maggot, Rhagoletis pomonella (Walsh), was monitored with baited yellow panels and red spheres in commercial orchards, abandoned orchards, and unsprayed backyard apple trees in 1998 and 1999. Apple maggot adults were captured in all apple habitats, but the capture levels in the abandoned orchards and unsprayed backyard trees tended to be higher than in the commercial orchards. Peak capture occurred between mid-July and late August in both years. Emergence cages seeded with infested fruits were used to investigate bivoltinism, which was observed in both years.

Animals↗
PubMed2002

Spectrofluorometric resolution of closely overlapping drug mixtures using chemometrics methods.

A modified parallel factors analysis (PARAFAC) algorithm with a penalty diagonalization error (PDE), newly proposed by the present authors, was utilized to simultaneously resolve drug mixtures of propranolol (PRO), dipyridamole (DIP) and amiloride (AMI) without any loss of sensitivity. The analyses were performed in aqueous solution. The experimental results demonstrated that the profiles of the spectra and the concentrations could be accurately resolved using the PDE algorithm with a high sensitivity and stable repeatability. That is to say, the closely overlapping problem of the spectra could be easily solved. Furthermore, simultaneous determinations of three kinds of tablets, which contain PRO, AMI and DIP, respectively, were successfully performed with satisfactory results.

Algorithms↗
PubMed2002

[Association between the genetic polymorphisms of beta2-adrenergic receptor gene and the asthma susceptibility and clinical phenotypes in a Chinese population].

OBJECTIVE: To determine whether genetic polymorphisms of beta2-adrenergic receptor gene affect asthma susceptibility and play a role in disease regulation. METHODS: One hundred and sixty-six unrelated childhood asthma cases and 32 families with 192 samples were studied. The polymorphisms at amino acid positions 16, 27, 164 and nucleic acid residue 523 were genotyped by polymerase chain reaction-restriction endonuclease digestion. RESULTS: The amino acid 164 Thr/Ile variant was seen only in the heterozygote form, and it occurred with a frequency of 3% which is similar to the published results among Caucasians. There were significant differences in the allele frequencies of the other 3 polymorphisms between Chinese and the published results among Caucasians (P<0.001). No polymorphism was found to be associated with total serum IgE, the number of positive prick skin test and FEV1. No significant association was noted between either the arginine-glycine 16 or the glutamine-glutamate 27 polymorphisms and the airway responsiveness to beta2-agonists in childhood asthma cases. CONCLUSION: In this study population, the authors were unable to confirm that the polymorphism of beta2-adrenergic receptor gene is a crucial factor of the susceptibility to asthma and a major genetic determinant of different clinical status.

Adult↗
PubMed2002

[Experimental study on prevention of diabetes complicated with tuberculosis by Mycobacterium vaccae].

OBJECTIVE: To study if Mycobacterium vaccae has any effect in prevention of rats with diabetes from tuberculosis. METHODS: Wistar rats with diabetes which were produced by injection of streptozotocin one week before were divided into four groups. Mycobacterium vaccae was injected into Wistar rats with diabetes and one month later H(37)R(v) was injected intravenously. The rats were sacrificed six weeks later to observe pathomorphologic changes in lung tissues. Indexes for evaluation included quantitative culture of Mycobacterium tuberculosis of lung tissue, tubercular lesion, count of Mycobacterium tuberculosis in alveolar macrophages and histopathological changes. RESULTS: Pathological change index of tubercular lesion, quantitative culture of Mycobacterium tuberculosis in lung tissue, count of Mycobacterium tuberculosis in alveolar macrophages were 2.5 +/- 0.7, (4.1 +/- 0.6) x 10(4) cfu, 2.6 +/- 0.9 respectively in group injected with Mycobacterium vaccae, while 3.3 +/- 0.5, (9.9 +/- 1.0) x 10(4) cfu, 7.2 +/- 0.7 respectively in the control group. Statistically significant differences were found between the two groups (P < 0.05, < 0.01, < 0.01 respectively). The histopathological changes of lung tissue in group of diabetes complicated with tuberculosis revealed that the lesions were predominant with necrosis, while in group injected with Mycobacterium vaccae, the lesions showed proliferation mainly. This indicated that Mycobacterium vaccae could decrease the damage to the lung tissue of the rat with diabetes by tubercle bacilli. CONCLUSION: Mycobacterium vaccae might play a role in prevention of rat with diabetes from tuberculosis.

Animals↗
PubMed2002

[A discussion on utility and purposed value of obesity and abdomen obesity when body mass index, waist circumference, waist to hip ratio used as indexes predicting hypertension and hyper-blood glucose].

OBJECTIVE: Discussion on utility and purposed value of obesity and abdomen obesity when body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR) used as indexes predicting hypertension, hyper-blood glucose, and both clusters, to provide scientific basis for the decision on the indexes and their cut-off points of obesity and abdomen obesity in Chinese people. METHODS: Using the data of diabetes mellitus (DM) from epidemiological studies carried out in 11 provinces/autonomous regions/municipalities of China from July 1995 to June 1997. Partial relative analysis, logistic multi-factors regression analysis, interaction analysis were used. Relative risk (RR), attributable risk proportion (ARP) and population attributable risk proportion (PARP) of hypertension, hyper-blood glucose, and the both cluster as BMI, WC, WHR with the different cut off points were analysed. RESULTS: 1) The correlations between BMI, WC and blood pressure, blood glucose were better than the WHR. 2) After adjusted by age, sex, occupation leisure physical activity, education degree and the family history of DM, the results suggested that BMI, WC, WHR were important predictive factors, with relative importance as BMI > WC > WHR. 3) There were augment interactions on BMI, WC and WHR with hypertension, hyper-blood glucose, with the interaction of BMI and WC in particular. Their pure attributable interaction proportion were from 5.95% to 29.34%. 4) The values of RR were about 2.5 when BMI >/= 23, >/= 24 and >/= 25, suggesting the relationship with exposure factors and diseases were with medium and high maleficent extent. Their ARP were from 0.580 to 0.623 with PARP from 0.259 to 0.425. The values of RR were from 2.06 to 3.08 as WC >/= 85 cm in males, WC >/= 80 cm in females while WC >/= 90 cm in males, WC >/= 80 cm in females, which suggested that the relationship with exposure factors and diseases were in medium and high maleficent extent. Their ARP were from 0.515 to 0.676 while PARP from 0.241 to 0.431. CONCLUSIONS: Since the maleficent extent of exposure factors to diseases, the acceptability for overweight and obesity in population, and the prevention and care for overweight and obesity were just in the introduction stage in China. The utility value of predicted hypertension, hyper-blood glucose in BMI and WC seemed to be better then in WHR. We suggested that BMI used as the obesity index, with the diagnostic cut-off point BMI >/= 24. WC as the abdomen obesity index. The diagnostic cut-off points are suggested to be WC >/= 85 cm in males, and WC >/= 80 cm in females.

Adult↗
PubMed2002

[Syntheses and antitumor activities of the derivatives of P-methyl goniotriol in vitro].

AIM: To find derivatives of p-methyl-goniotriol with more potent antitumor activities and lacking undesirable effects. METHODS: Eighty derivatives of p-methyl-goniotriol have been synthesized in nine steps from alpha-D-glucoheptonic-delta-lactone (2). Compound 2 reacted with acetone in the catalyzer, H2SO4 and anhydrous MgSO4, and then reacted with 60% aqua HOAc, finally was oxidized by NaIO4 at room temperature into aldehyde 3 in a yield of 71.3%. The aldehyde 3 reacted immediately with P-CH3-PhMgBr giving mixture 4. The mixture 4 was oxidized by NaIO4, reacted with Ph3P = CHCO2Et and then induced by catalyzer. 1,8-Diazabicylclo[5, 4, 0]undec-7-ene in THF providing the compounds 6 and 7. The esterfication of 6 with cinnamyl chloride et al in 4-dimethylaminopyridine, Et3N gave the esters 8a-h. Acid hydrolysis of the acetone protecting group of 8a-h in 75% aqua HOAc gave compounds 9a-h. Their chemical structures were confirmed by IR, 1HNMR, MS and element analysis. The antitumor activities of the compounds were screened by MTT methods. RESULTS: Fifteen derivatives of p-methyl-goniotriol (7, 8b-h, 9b-h) are new compounds. CONCLUSION: Pharmacological tests indicate that these compounds showed antitumor activities toward tumor cells (A2780, HCT-8, Bel742, KB) in vitro. The antitumor activities of 8b, 8d, 8g and 9h were more potent than howiinol A.

Antineoplastic Agents↗
PubMed2002

[Changes in element content in Aedes albopictus infected by dengue virus type II].

OBJECTIVE: To study the changes in the content of elements in Aedes albopictus after dengue virus type II (DV2) infection. METHODS: DV2 were injected into the thorax of Ae. albopictus. The content of elements in Ae. albopictus was determined on days 5, 10 and 20 after infection respectively and compared with those in the same instar non-infected mosquitoes. RESULTS AND CONCLUSION: For the group of day 5 after DV2 infection, the content of elements Ca, S and Cr increased remarkably compared to those in the control group; while the content of elements Zn, Mo, Pb, Ce and Cl reduced remarkably. For the group of day 10 after infection, the content of Na, Mg, Zn, Se, Ce and S increased remarkably compared to those in the control; only that of Fe was lower remarkably than the control. For the group of day 20 after infection, the content of elements Ti and Pb increased remarkably than that of the control; while the content of Na, Zn, Cr and Ce reduced remarkably.

Aedes↗
PubMed2002

[Study on the oxidative coupling of p-amino-N,N-dimethylaniline with 1-amino-8-naphthol-3,6-disulfonic acid and its application].

A new catalytic spectrophotometic method for the determination of trace chromium (VI) is reported in this paper. The method is based on the catalytic action of chromium (VI) on the oxidative coupling of p-Amino-N,N-dimethylaniline dihydrochloride and 1-Amino-8-naphthol-3,6-disulfonic acid to form a colored dye (lambda max = 516 nm) in the presence of hydrogen peroxide. The mechanism of the reaction was discussed and its optimum conditions were established. The linear range of this method was 0.08-0.40 mg.L-1 and the relative standard deviation was found to be 1.1% for Cr(VI) (11 replicates). The detection limit for Cr(VI) is 2.0 x 10(-6) g.L-1. The method was used to determine Cr(VI) in waste water successfully.

Catalysis↗
PubMed2002

[Environmental stress-induced programmed cell death in higher plants].

Programmed cell death (PCD) research in higher plants has blossomed in the past ten years. Many evidences suggested that reactive oxygen species,ethylene, Ca2+, salicylic acid, nitric oxide etc. are important signal molecules during environmental stress-induced PCD in plants. Like apoptosis in animals, there also exists a Caspase-dependent PCD signal transduction pathway, in which mitochondrion plays a role of central depot.

English Abstract↗
PubMed2001

The platelet receptor GPVI mediates both adhesion and signaling responses to collagen in a receptor density-dependent fashion.

The platelet response to collagen is a primary event in hemostasis and thrombosis, but the precise roles of the numerous identified platelet collagen receptors remain incompletely defined. Attention has recently focused on glycoprotein VI (GPVI), a receptor that is expressed on platelets in association with a signaling adapter, the Fc receptor gamma chain (Fc Rgamma). Genetic and pharmacologic loss of GPVI function results in loss of collagen signaling in platelets, but studies to date have failed to demonstrate that GPVI-Fc Rgamma expression is sufficient to confer collagen signaling responses. These results have led to the hypothesis that collagen responses mediated by GPVI-Fc Rgamma may require the collagen-binding integrin alpha2beta1 as a co-receptor, but this model has not been supported by a recent study of mouse platelets lacking alpha2beta1. In the present study we have used a novel anti-GPVI monoclonal antibody to measure the level of GPVI on human platelets and to guide the development of GPVI-expressing cell lines to assess the role of GPVI in mediating platelet collagen responses. GPVI receptor density on human platelets appears tightly regulated, is independent from the level of alpha2beta1 expression, and significantly exceeds that on previously characterized GPVI-expressing RBL-2H3 cells. Using newly generated GPVI-expressing RBL-2H3 cells with receptor densities equivalent to that on human platelets, we demonstrate that GPVI expression confers both adhesive and signaling responses to collagen in a graded fashion that is proportional to the GPVI receptor density. These results resolve some of the conflicting data regarding GPVI-collagen interactions and demonstrate that 1) GPVI-Fc Rgamma expression is sufficient to confer both adhesion and signaling responses to collagen, and 2) GPVI-mediated collagen responses are receptor density-dependent at the receptor levels expressed on human platelets.

3T3 Cells↗
PubMed1998

A New, Aqueous (1)H NMR Shift Reagent Based on Host-Guest Molecular Recognition Principles for Organic Compound Structural Analysis: Non-covalent pi-pi and Hydrophobic Interactions Using a Supramolecular Host, [CpRh(2'-deoxyadenosine)](3)(OTf)(3).

We have discovered that the supramolecular host [CpRh(2'-deoxyadenosine)](3)(OTf)(3) (1, Cp = eta(5)-C(5)Me(5), OTf = CF(3)SO(3)(-)) has utility as a new, aqueous (1)H NMR shift reagent, via a host-guest molecular recognition process that occurs by non-covalent pi-pi and hydrophobic interactions, with a wide variety of H(2)O-soluble organic substrates. These organic compound guests that we present, to illustrate the utility of host 1 as a novel, aqueous (1)H NMR shift reagent, encompass examples such as aromatic carboxylic acids, phenylacetic acid (G1), 1-naphthoic acid (G2), and 2-naphthoic acid (G3), an aliphatic carboxylic acid, cyclohexylacetic acid (G4), as well as biological compounds, a di- and a tetrapeptide containing terminal L-tryptophan (Trp) or L-phenylalanine (Phe) groups, L-Trp-L-Phe (G5) and L-Trp-L-Met-L-Asp-L-Phe amide (G6) in the pH range 5-10. A discussion of the molecular recognition parameters that effect the (1)H NMR shifts of the organic guests and a comparison with the water-soluble lanthanide shift reagents (LSRs) will be presented to demonstrate the usefulness of this aqueous molecular receptor as an aid for organic compound structural analysis.

Journal Article↗
PubMedDate not supplied

Male genital tract antioxidant enzymes: their source, function in the female, and ability to preserve sperm DNA integrity in the golden hamster.

Recently, we reported that male accessory sex gland (ASG) secretions protect sperm genomic integrity by demonstrating that DNA damage was more extensive in sperm not exposed to the secretions. The present study was conducted to find out if ASGs secrete the main antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx or GSH-Px), and catalase (CAT) and if the most abundant one, SOD, can protect those sperm that were not exposed to ASG secretions against NADPH-induced oxidative stress. Four experimental groups of male golden hamsters were used: intact animals with proven fertility, animals with all major ASGs removed (TX), animals that were bilaterally vasectomized, and sham-operated controls. SOD, CAT, and GPx activities were measured in secretions from all 5 ASGs and sperm-free uterine flushing from virgin females and those mated with the experimental males. The alkaline comet assay was used to analyze DNA integrity of the TX group sperm after incubation in a medium containing 50 U/mL of SOD along with 0 to 20 mmol/L NADPH. The main antioxidant enzyme in ASGs was SOD from coagulating glands (P <.05) and GPx together with CAT from ampullary glands (P <.05). Uterine flushing of ejaculates that contained ASG secretions had more SOD and CAT activities than those with epididymal secretions alone (P <.05 and P <.001, respectively), whereas activity of GPx was the same (P >.05). Addition of SOD in vitro dose dependently decreased the incidence of single-strand DNA damage in sperm not exposed to ASG secretions incubated in the presence of 0 to 20 mmol/L NADPH (P <.001). These results indicated that, in terms of abundance, SOD was the main antioxidant enzyme secreted by male ASGs, whereas CAT was the second one. The GPx activity came from both epididymis and ASGs. We conclude that ASG secretions play a significant role in protecting sperm against oxidative stress.

Alkalies↗
PubMedDate not supplied

Generic bioaffinity silicone surfaces.

Synthetic polymer surfaces require surface modification to improve biocompatibility. A generic route to biocompatible silicone elastomers is described involving high yield surface functionalization of standard silicones with hydrosilanes, hydrosilylation using asymmetric, allyl-, NSC-terminated PEO of narrow molecular weight, and covalent modification in one step with amine-containing biological molecules including oligopeptides (YIGSR, RGDS), proteins (EGF, albumin, fibrinogen, mucin), and glycosaminoglycans (heparin). Efficient, high-density binding (e.g., 0.2 EGF molecules/nm2) was demonstrated using radiolabeling studies. The resulting surfaces were demonstrated to be biocompatible by further reaction with biomolecules, for example, thrombosis suppression on surfaces modified by heparin + ATIII, and the formation of confluent corneal epithelial cell layers on EGF, RGDS, or YIGSR surfaces.

Biocompatible Materials↗