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Biomedical subjects

J Wang

Publications and source records attributed to J Wang.

At least 271 records · Page 15Linked to original sources
PubMed2003

Fas siRNA reduces apoptotic cell death of allogeneic-transplanted hepatocytes in mouse spleen.

BACKGROUND: Synthetic siRNAs 21 to 23 nucleotides in length silence gene expression posttranscriptionally, and RNA interference targeting Fas protects mice from fulminant hepatitis. Fas-mediated apoptosis has also been implied in the mechanism of hepatocyte apoptosis upon allogenic hepatocyte transplantation (HTx), and blockade of Fas and Fas ligand interaction successfully promotes the repopulation of allogenic liver cells in recipient spleens. In the present study, we further investigated the protective effects of Fas silencing on allogeneic hepatocytes transplanted into mouse spleens. MATERIALS AND METHODS: Hepatocytes were isolated from BALB/c mice and mock transfected or transfected with Fas siRNA or GFP siRNA (n = 8/group). The expression of Fas was examined by RT-PCR and flow cytometric analysis. Forty-eight hours later, the cells were transplanted into spleens of allogenic B6 mice. Spleens were harvested on day 21 after transplantation. Apoptosis was assessed by TUNEL assay, survival of hepatocytes by alanine transaminase (ALT) assay. RESULTS: Fas siRNA transfection reduced Fas expression on hepatocytes at both mRNA and protein levels (P <.05). Upon transplanting into recipient spleens, hepatocytes transfected with Fas siRNA demonstrated a lower percentage of apoptosis detected by TUNEL (6 +/- 3% in Fas siRNA group vs 12 +/- 5% in GFP siRNA group and 10 +/- 3% in mock transfected group; P <.05), and increased survival as determined by ALT assay (38.2 +/- 10.6 IU/g in Fas siRNA group vs 21.3 +/- 8.4 IU/g in GFP siRNA group and 18.5 +/- 5.9 IU/g in mock-transfected animals). CONCLUSIONS: Fas silencing by RNA interference reduces apoptosis and increases survival of allogenic transplanted hepatocytes, and thus holds promise to inhibit acute rejection after hepatocyte transplantation.

Animals↗
PubMed2003

Hemocompatibility of titanium oxide films.

Hemocompatibility is a key property of biomaterials that come in contact with blood. Surface modification has shown great potential for improving the hemocompatibility of biomedical materials and devices. In this paper, we describe our work of improving hemocompatibility with Ti-O thin films prepared by plasma immersion ion implantation and deposition and by sputtering. The structure and surface chemical and physical properties of the films were characterized by X-ray diffraction, Auger electron spectroscopy, atomic force microscopy (AFM), contact angle measurement, and Hall effect measurement. The behavior of fibrinogen adsorption was investigated by 125I radioactive isotope labeling and AFM. Systematic evaluation of hemocompatibility, including in vitro clotting time, thrombin time, prethrombin time, platelet adhesion, and in vivo implantation into dog's ventral aorta or right auricle from 17 to 90 days, proved that Ti-O films have excellent hemocompatibility. It is suggested that the significantly lower interface tension between Ti-O films and blood and plasma proteins and the semiconducting nature of Ti-O films give them their improved hemocompatibility.

Adsorption↗
PubMed2003

Sex differences in the magnocellular subdivision of the medial preoptic nucleus in Syrian hamsters.

Exposure to pheromonal cues initiates male mating behavior. Pheromones are processed within a pathway that converges on the magnocellular subdivision of the medial preoptic nucleus. Lesions of this area eliminate male copulatory behavior, but do not affect anogenital investigation. Exposure to pheromones stimulates cells of the magnocellular subdivision of the medial preoptic nucleus in a sex-specific manner. In this study, we hypothesize that sex differences in cell number may underlie sex differences in pheromone-induced neural stimulation. The current study used unbiased stereological methods to identify sexual dimorphisms in the magnocellular subdivision of the medial preoptic nucleus. Sex differences were found in the number and density of neurons, but not in overall volume or neuron volume. Consequently, the total volume is not sexually differentiated because neurons are more densely packed within the male magnocellular subdivision of the medial preoptic nucleus. These results support the hypothesis that additional neurons in the magnocellular subdivision of the medial preoptic nucleus are critical for the expression of male copulatory behaviors in adulthood. Furthermore, they suggest that sexual differentiation of the magnocellular subdivision of the medial preoptic nucleus is an important process that forms the anatomical basis for sex-specific behavioral responses to pheromonal stimulation.

Animals↗
PubMed2003

Mu-opioid receptors are located postsynaptically and endomorphin-1 inhibits voltage-gated calcium currents in premotor cardiac parasympathetic neurons in the rat nucleus ambiguus.

Activation of opioid receptors in the CNS evokes a dramatic decrease in heart rate which is mediated by increases in inhibitory parasympathetic activity to the heart. Injection of opiates into the nucleus ambiguus, where premotor cardiac parasympathetic nucleus ambiguus neurons are located elicits an increase in parasympathetic cardiac activity and bradycardia. However, the mechanisms responsible for altering the activity of premotor cardiac parasympathetic nucleus ambiguus neurons is unknown. This study examined at the electron microscopic level whether premotor cardiac parasympathetic nucleus ambiguus neurons possess postsynaptic opioid receptors and whether mu-opioid receptor agonists alter voltage-gated calcium currents in these neurons. Premotor cardiac parasympathetic nucleus ambiguus neurons were identified in the rat using retrograde fluorescent tracers. One series of experiments utilized dual-labeling immunocytochemical methods combined with electron microscopic analysis to determine if premotor cardiac parasympathetic nucleus ambiguus neurons contain mu-opioid receptors. In a second series of experiments whole cell patch clamp methodologies were used to determine whether activation of postsynaptic opioid receptors altered voltage-gated calcium currents in premotor cardiac parasympathetic nucleus ambiguus neurons in brainstem slices. The perikarya and 78% of the dendrites of premotor cardiac parasympathetic nucleus ambiguus neurons contain mu-opioid receptors. Voltage-gated calcium currents in premotor cardiac parasympathetic nucleus ambiguus neurons were comprised nearly entirely of omega-agatoxin-sensitive P/Q-type voltage-gated calcium currents. Activation of mu-opioid receptors inhibited these voltage-gated calcium currents and this inhibition was blocked by pretreatment with pertusis toxin. The mu-opioid receptor agonist endomorphin-1, but not the mu-opioid receptor agonist endomorphin-2, inhibited the calcium currents. In summary, mu-opioid receptors are located postsynaptically on premotor cardiac parasympathetic nucleus ambiguus neurons. The mu-opioid receptor agonist endomorphin1 inhibited the omega-agatoxin-sensitive P/Q-type voltage-gated calcium currents in premotor cardiac vagal nucleus ambiguus neurons. This inhibition is mediated via a G-protein mediated pathway which was blocked by pretreatment with pertusis toxin. It is possible that the inhibition of calcium currents may act to indirectly facilitate the activity of premotor cardiac parasympathetic nucleus ambiguus neurons by disinhibition, such as by a reduction in inhibitory calcium activated potassium currents.

Analgesics, Opioid↗
PubMed2003

Altered auditory-evoked potentials in mice carrying mutated human amyloid precursor protein and presenilin-1 transgenes.

Transgenic mice carrying human APPswe and PS1-A264E transgenes (A/P mice) have elevated levels of the highly fibrillogenic amyloid Abeta(1-42) (Abeta) and develop amyloid plaques around the age of 9 months. Our aim was to find whether the gradual accumulation of Abeta in these mice can be detected with long-term recording of auditory-evoked potentials. The A/P double-mutant mice had impaired auditory gating and a tendency toward increased latency of the cortical N35 response, but these changes were not age-dependent between 7 and 11 months of age. In a control experiment that included also APP and PS1 single-mutant mice, the A/P double-mutant mice had weaker auditory gating than either APP or PS1 mice. In contrast, increased N35 latency was found in both A/P and APP mice compared with nontransgenic or PS1 mice. The Abeta40 and Abeta42 levels were robustly increased in A/P mice and Abeta40 moderately increased also in APP mice. Plaques were deposited only in A/P mice. We conclude that the impaired auditory gating is associated with the overproduction Abeta42 but does not reflect its amount. In contrast, increased N35 latency is related to the APP genotype independent of Abeta42 production.

Alzheimer Disease↗
PubMed2003

Changes in [14C]-2-deoxyglucose uptake in the auditory pathway of hamsters previously exposed to intense sound.

The current study evaluated changes in [14C]-2-deoxyglucose (2-DG) uptake along the auditory pathways of hamsters that were exposed unilaterally to intense sound. The measurement of the acoustically evoked auditory brainstem responses indicated that intense sound exposure caused asymmetrical hearing loss. The 2-DG results revealed some changes in metabolic activity in exposed animals, as compared to unexposed animals. Significant decreases in 2-DG uptake were found in the ipsilateral anteroventral and posteroventral cochlear nucleus, with respect to the exposed left ears. Exposed animals also showed significant increases in the ipsilateral nucleus of the lateral lemniscus, central nucleus of inferior colliculus and medial geniculate body. No significant changes in uptake were observed in the ipsilateral dorsal cochlear nucleus, superior olivary complex, auditory cortex and any contralateral structures. The mechanisms for the observed changes in 2-DG uptake are discussed.

Acoustic Stimulation↗
PubMed2003

Homeostasis of the extracellular matrix of normal and osteoarthritic human articular cartilage chondrocytes in vitro.

OBJECTIVE: In normal articular cartilage cells, the IGFRI/insulin-like growth factor 1 (IGF-1) autocrine pathway was shown to overrule the catabolic effects of the IL-1/IL-1RI pathway by up-regulation of the IL-1RII decoy receptor. The activity of the IGF-1/IGFR1 and IL-1/IL-1R pathways, and of the IL-1RII control mechanism in the synthesis and turnover of the extracellular matrix (ECM) by chondrocytes from normal and osteoarthritic (OA) articular cartilage was compared in order to identify possible therapeutic targets of this disease. METHODS: Phenotypically stable human articular cartilage cells were obtained from normal and OA cartilage of the same knee showing focal OA. The cells were cultured in alginate beads over 1 week to re-establish the intracellular cytokine and growth factors, to reexpress the respective plasma membrane receptors and to reach equilibrium in accumulated cell-associated matrix (CAM) compounds. Following liberation of the cells from the alginate beads, the levels of cell-associated matrix (CAM) aggrecan, type II collagen and fibronectin, of intracellular IGF-1, IL-1alpha and beta and of their respective plasma membrane-bound receptors, IGFR1, IL-1RI and the decoy receptor IL-1RII, were assayed using flow cytometry. RESULTS: Coordinated production and accumulation of CAM aggrecan and type II collagen under the effect of the IGFR1/IGF-1 autocrine pathway-as documented for chondrocytes from healthy controls-was absent when the chondrocytes had been obtained from OA joints. When compared with cells obtained from normal tissues, chondrocytes from fibrillated OA cartilage expressed significantly higher intracellular IGF-1 levels and plasma membrane-bound IGFR1. At the same time, significantly higher intracellular IL-1alpha and beta levels and upregulated plasma membrane-bound IL-1RI were observed. Plasma membrane-bound IL-1RII decoy receptor was downregulated in OA chondrocytes. The levels of CAM aggrecan, type II collagen and fibronectin were significantly reduced in the chondrocytes obtained from pathological tissue. CONCLUSION: Paired analysis of normal and OA chondrocytes from the same knee joint has shown an enhanced capacity of chondrocytes from OA cartilage to produce ECM macromolecules. However, the same cells have increased catabolic signalling pathways. As a consequence of this increased IL-1 activity and the reduced amounts of IL-1RII decoy receptor, less of the produced ECM macromolecules may persist in the CAM of the OA chondrocytes.

Adult↗
PubMed2003

Effect of sevoflurane on human neutrophil apoptosis.

BACKGROUND AND OBJECTIVE: Both chronic occupational exposure to volatile anaesthetic agents and acute in vitro exposure of neutrophils to isoflurane have been shown to inhibit the rate of apoptosis of human neutrophils. It is possible that inhibition of neutrophil apoptosis arises through delaying mitochondrial membrane potential collapse. We assessed mitochondrial depolarization and apoptosis in unexposed neutrophils and neutrophils exposed to sevoflurane in vivo. METHODS: A total of 20 mL venous blood was withdrawn pre- and postinduction of anaesthesia, the neutrophils isolated and maintained in culture. At 1, 12 and 24 h in culture, the percentage of neutrophil apoptosis was assessed by dual staining with annexin V-FITC and propidium iodide. Mitochondrial depolarization was measured using the dual emission styryl dye JC-1. RESULTS: Apoptosis was significantly inhibited in neutrophils exposed to sevoflurane in vivo at 24 (exposed: 38 (12)% versus control: 28 (11)%, P = 0.001), but not at 1 or 12 h, in culture. Mitochondrial depolarization was not delayed in neutrophils exposed to sevoflurane. CONCLUSIONS: The most important findings are that sevoflurane inhibits neutrophil apoptosis in vivo and that inhibition is not mediated primarily by an effect on mitochondrial depolarization.

Anesthetics, Inhalation↗
PubMed2003

A mouse model of the atopic eczema/dermatitis syndrome by repeated application of a crude extract of house-dust mite Dermatophagoides farinae.

BACKGROUND: We cultured Dermatophagoides farinae (Df), one of the most common mites in house dust and the most important allergen among natural allergens. With this material, we attempted to produce an animal model of the atopic eczema/dermatitis syndrome (AEDS). METHODS: We cultured Df mites in high density and prepared a crude extract of Df (DfE) together with the culture medium. We applied the extract to the back skin of NC/Nga and BALB/c mice three times per week for 8 weeks. RESULTS: In the NC/Nga group, dryness or scaling appeared on the skin, and scratching behavior increased at the second week in the DfE-treated group. Skin erosion and hemorrhage occurred at the fourth week. The epidermis thickened and deepened into the upper dermis, in which mast cells were highly accumulated, corresponding with the skin lesion of AEDS patients. Specific IgE and IgG to DfE and total IgE were elevated in the sera. Mice treated with an extract of mite culture medium did not develop skin lesions. In the BALB/c group, mice developed specific IgE and IgG to DfE, however, no typical skin lesions appeared. Mast cells in the upper dermis did not increase. CONCLUSIONS: Repeated painting of Dermatophagoides extract produced IgE-associated AEDS-like lesions on the skin of NC mice.

Allergens↗
PubMed2003

Differences in body composition between Singapore Chinese, Beijing Chinese and Dutch children.

OBJECTIVES: To compare the relationship between body mass index (BMI) and body fat percentage (BF%) in children of different ethnic background. DESIGN: Cross-sectional observational study. SETTINGS: The study was performed in three different locations, Singapore, Beijing and Wageningen (The Netherlands). SUBJECTS: In each centre 25 boys and 25 girls, aged 7-12 y, were selected. They were matched on age, sex and body height. METHODS: Body weight and body height was measured following standardized procedures. The body mass index (BMI) was calculated as weight/height squared (kg/m(2)). Body fat was measured by densitometry in Beijing and Wageningen and by dual energy X-ray absorptiometry (DXA) in Singapore. The DXA measurements in Singapore were validated against densitometry. RESULTS: There were no significant differences in BF% or BMI within each gender group across the three study sites. However, after controlling for (non-significant) differences in age and BF%, the Singapore children had a lower (mean+/-s.e.) BMI (15.6+/-0.3) than the Beijing 17.6+/-0.3) and Wageningen (16.9+/-0.3) children. For the same BMI, age and sex the Singapore children had a significant higher BF% (24.6+/-0.7) than the Beijing (19.2+/-0.8) and Wageningen (20.3+/-0.7) children. CONCLUSIONS: The study strongly suggests that the relationship between BF% and BMI (or weight and height) is different among children of different ethnic background. Consequently growth charts and BMI cut-off points for underweight, overweight and obesity in children may have to be ethnic-specific.

Absorptiometry, Photon↗
PubMed2003

The Great Wall of China: a physical barrier to gene flow?

One population from each of six plant species along both sides of the Juyong-guan Great Wall, together with one population from each of five species along both sides of a path on a mountain top near Juyong-guan, were selected to study the effect of the Great Wall as a barrier on genetic differentiation between two subpopulations using RAPD markers. Significant genetic differentiation was found between the subpopulations on both sides of the Great Wall. A wind-pollinated woody species, Ulmus pumila, showed less genetic differentiation than four insect-pollinated species: Prunus armeniaca, Ziziphus jujuba, Vitex negundo, and Heteropappus hispidus. Cleistogenes caespitosa, a wind-pollinated perennial herb, displayed more genetic differentiation between subpopulations than the insect-pollinated species because of its propagation strategy. Although AMOVA analysis showed that subpopulations divided by a mountain path had diverged genetically, the variance component between the subpopulations on both sides of the Great Wall was significantly larger than that between the subpopulations at the control site. Therefore, it is reasonable to deduce that the Juyong-guan Great Wall has served as a physical barrier to gene flow between subpopulations separated for more than 600 years.

Biological Evolution↗
PubMed2003

Ileal adenocarcinoma in a mild phenotype of abetalipoproteinemia.

Abetalipoproteinemia (ABL) is a rare autosomal recessive disorder that is characterized by defective assembly and secretion of plasma apolipoprotein (apo) B-containing lipoproteins. This disorder results from mutations in the MTP gene encoding the microsomal triglyceride transfer protein. We report a 58-year-old male homozygote for a missense mutation, S590I, in MTP. The patient had a lifelong history of fat malabsorption, but was only diagnosed with ABL at age 52, based upon such classic features as absence of apo B-containing lipoproteins, acanthocytosis, atypical retinitis pigmentosa and markedly depressed serum beta-carotene concentration. However, his presentation was notable not only by survival to the sixth decade of life without specific treatment, but also by the absence of neurological involvement and by normal serum vitamin E concentration. He subsequently developed adenocarcinoma of the ileum, which required ileal resection. Therefore, this missense mutation appears to be associated with a late-presenting and relatively mild ABL phenotype that lacks some classical features, particularly neuropathy, but appears to be associated with other atypical features, specifically small intestinal cancer.

Abetalipoproteinemia↗
PubMed2003

Discordance of endothelial nitric oxide synthase in the arterial wall and its circulating products in baboons: interactions with redox metabolism.

BACKGROUND: Although peripheral arteries and circulating factors have been frequently used to assess systemic or central arterial, such as coronary artery, endothelial nitric oxide synthase (eNOS) functions, there is no direct evidence to support that they are related. DESIGN: We explored relationships in eNOS levels among coronary, aortic, carotid and brachial arteries, and interactions with redox metabolisms in 40 necropsied baboons (Papio hamadryas). RESULTS: We found no correlations in eNOS or NOx levels among all four arteries (R: 0.02-0.19, P > 0.05). While eNOS levels were high in both coronary (133.78 +/- 10.9 pg mg-1 protein) and aortic arteries (168.53 +/- 16.32 pg mg-1 protein), they were low in brachial (82.88 +/- 5.5 pg mg-1 protein) and carotid (89.83 +/- 7.15 pg mg-1 protein) arteries. Arterial eNOS were not correlated with plasma NOx either. However, coronary and aortic eNOS were positively correlated with the corresponding arterial total antioxidant status (TAS) (r = 0.638, P= 0.001, and r = 0.615, P= 0.0001). Coronary eNOS was also negatively associated with coronary advanced glycation end products (AGE) (r = -0.454, P= 0.003). Furthermore, there were significant associations in TAS levels between plasma and arterial wall extracts (R: 0.344-0.369, P < 0.05) and among arteries of different anatomic sites (R: 0.637-0.877, P < 0.001). While arterial TAS was negatively correlated with corresponding arterial AGE, TAS in the arterial wall and plasma were positively associated with plasma AGE. CONCLUSIONS: Our study shows that eNOS is differentially expressed in different anatomic sites and is not associated with plasma NOx, suggesting that brachial eNOS may not be used to assess coronary eNOS. The positive or negative associations between eNOS and TAS or AGE, especially in the coronary artery, indicate an important role of eNOS in arterial wall redox balance.

Animals↗
PubMed2003

Genetic analysis of spatial foraging patterns and resource sharing in bumble bee pollinators.

Conservation biologists, evolutionary ecologists and agricultural biologists require an improved understanding of how pollinators utilize space and share resources. Using microsatellite markers, we conducted a genetic analysis of space use and resource sharing at several spatial scales among workers of two ecologically dissimilar bumble bee species (Bombus terrestris and B. pascuorum) foraging in an urban landscape (London, UK). At fine scales, the relatedness of workers visiting small patches of flowers did not differ significantly from zero. Therefore, colonies shared flower patches randomly with other colonies, suggesting that worker scent-marks deterring visits to unrewarding flowers have not evolved as signals benefiting nestmates. To investigate space use at intermediate scales, we developed a program based on Thomas & Hill's maximum likelihood sibship reconstruction method to estimate the number of colonies utilizing single sites. The average number of colonies (95% confidence limits) sending workers to forage at sites of approximately 1 ha in area was 96 colonies (84-118) in B. terrestris and 66 colonies (61-76) in B. pascuorum. These values are surprisingly high and suggested that workers travelled far from their colonies to visit the sites. At the landscape scale, there was little or no genetic differentiation between sites. We conclude that urban habitats support large bumble bee populations and are potentially valuable in terms of bumble bee conservation. In addition, bumble bee-mediated gene flow in plants is likely to occur over large distances and plant-bumble bee conservation requires landscape-scale action.

Alleles↗