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Biomedical subjects

S Wang

Publications and source records attributed to S Wang.

At least 433 records · Page 24Linked to original sources
PubMed2000

Enhanced type I immune response to a hepatitis B DNA vaccine by formulation with calcium- or aluminum phosphate.

DNA vaccines induce protective humoral and cell-mediated immune responses in several animal models. When compared with conventional vaccines, however, DNA vaccines often induce lower antibody titers. We have now found that formulation of a DNA vaccine encoding hepatitis B surface antigen with calcium- or aluminum phosphate adjuvants can increase antibody titers by 10-100-fold and decrease the immunogenic dose of DNA by 10-fold. Furthermore, boosting an HBs protein-primed response with the adjuvanted DNA vaccine resulted in a dramatic increase in the HBs-specific IgG2a response reflecting a shift towards a TH1 response. The mechanism by which aluminum phosphate exerts its adjuvant effect is not through increased expression of HBsAg in vivo; rather, the adjuvant appears to increase the number and affinity of HBs peptide antigen-specific IFN-gamma and IL-2 secreting T cells.

Adjuvants, Immunologic↗
PubMed2000

Composite Au/TiO(2) Nanoparticles: Synthesis, Characterization, and Assembly by Using Potentiostatic Technique.

Composite Au/TiO(2) nanoparticles were synthesized using TiO(2) nanoparticles as nuclei. The particles were characterized by UV-vis spectroscopy, zeta potential, EDS, and TEM. The mean diameter of the particles is about 23.6 nm, and the position of the surface plasma absorption band peak is at 533 nm, with a red shift of 15 nm compared with that of Au sol. The zeta potential is +31.3 mV. Monolayers of composite Au/TiO(2) nanoparticles were obtained using the potentiostatic technique. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Fluorescence in situ hybridization identifies inversion 16 masked by t(10;16)(q24;q22), t(7;16)(q21;q22), and t(2;16)(q37;q22) in three cases of AML-M4Eo.

Bone marrow or peripheral blood from three patients had a t(10;16)(q24;q22), t(7;16) (q21;p13.1), and t(2;16)q37;q22), respectively. In all cases, fluorescence in situ hybridization confirmed an inv(16) masked by the translocation. The three patients were diagnosed with acute myelomonocytic leukemia and increased eosinophils. Because inv(16) has a favorable prognosis, identification of masked inv(16) will promote improved management of these cases. Therefore, all cases that have atypical rearrangement of chromosome 16 should be investigated for a possible inversion.

Adult↗
PubMed2000

Hepatocyte growth factor/scatter factor is a neurotrophic survival factor for lumbar but not for other somatic motoneurons in the chick embryo.

Hepatocyte growth factor/scatter factor (HGF/SF) is expressed in the developing limb muscles of the chick embryo during the period of spinal motoneuron (MN) programmed cell death, and its receptor c-met is expressed in lumbar MNs during this same period. Although cultured motoneurons from brachial, thoracic, and lumbar segments are all rescued from cell death by chick embryo muscle extract (CMX) as well as by other specific trophic agents, HGF/SF only promotes the survival of lumbar MNs. Similarly, treatment of embryos in ovo with exogenous HGF/SF rescues lumbar but not other somatic MNs from cell death. Blocking antibodies to HGF/SF (anti-HGF) reduce the effects of CMX on MN survival in vitro and decrease the number of lumbar MNs in vivo. The expression of c-met on MNs in vivo is regulated by a limb-derived trophic signal distinct from HGF/SF. HGF/SF is a potent, select, and physiologically relevant survival factor for a subpopulation of developing spinal MNs in the lumbar segments of the chick embryo.

Animals↗
PubMed2000

Obstructive sleep apnea syndrome in obese Singapore children.

We set out to determine the prevalence of obstructive sleep apnea syndrome (OSAS) among obese Singapore school children and identify risk factors for OSAS. This study was designed as a prospective study in three phases. Parents completed a questionnaire with regards to sleep and daytime symptoms in Phase 1. Children suspected to have OSAS based on the questionnaire and all with a percent ideal body weight (IBW) >/=180 were called for clinic visits in Phase 2. All whose percent IBW >/=180 and those in whom the physicians strongly suspected OSAS were subjected to a polysomnogram in phase 3. The children were recruited from the School Health Nutritional Clinic for obese children. The investigations were carried out at Tan Tock Seng Hospital. In all, 3,671 children were screened with the questionnaire. Of these, 146 were selected to undergo polysomnography. Twenty-six had abnormal sleep studies with apnea/hypoxia indices (AHIs) >5/hr. The significant clinical feature which correlated with OSAS was sleep sitting up (P = 0.005). The risk is higher in morbidly obese (IBW >/=180), with a prevalence of 13.3% (8/60), than in less obese children (IBW <180). One in eight (12.5%) of these children was asymptomatic and would have been missed based on the questionnaire. Presence of adenotonsillar hypertrophy led to increased risk of OSAS. The prevalence of OSAS was 0.7% (26/3,671) among the obese schoolchildren in Singapore, which is similar to the prevalence reported by others. Using discriminant analysis, the estimated prevalence increased to 5.7%. In the morbidly obese (IBW >/=180), the prevalence rate is higher at 13.3%.

Adenoids↗
PubMed2000

LEUNIG has multiple functions in gynoecium development in Arabidopsis.

The Arabidopsis gene LEUNIG was previously found to regulate floral organ identity. In this work we describe gynoecial phenotypes of newly isolated strong leunig alleles, leunig-101, leunig-102, and leunig-103. Gynoecia of these strong leunig mutants are united only at the basal part, leaving four unfused parts at the apex. Among them two medial ones are styles capped with stigmas, and two lateral ones are protrusions from valves. The gynoecium with unfused apex in leunig arises as a unit from a basal meristematic zone, suggesting that LEUNIG is required for normal congenital gynoecium fusion. The epidermal cells on growing inner surfaces of leunig gynoecium failed to fuse after they contact each other, indicating that LEUNIG is essential for the proper postgenital fusion. The epidermal cells at the very distal portion of protruded valves mimic those on wild-type styles, and those valves occasionally also have stigma-like tissues, indicating that LEUNIG function is required for the valve identity determination. We have also analyzed clavata1-4 leunig-101, clavata2-1 lug-101, fruitfull-1 leunig-101, and pinoid-1 leunig-101 double mutants. clavata1-4 leunig-101 and clavata2-1 leunig-101 exhibited additive phenotypes of single mutants, suggesting that LEUNIG and CLAVATA genes function in different pathways. In contrast, FRUITFULL and PINOID genes interact with LEUNIG to regulate gynoecium development. genesis 26:42-54, 2000.

Alleles↗
PubMed2000

A child with ALL and ETV6/AML1 fusion on a chromosome 12 due to an insertion of AML1 and loss of ETV6 from the homolog involved in a t(12;15)(p13;q15).

A 4-year-old boy was found to have acute lymphoblastic leukemia characterized by a t(12;15)(p13;q15). FISH investigation using a TEL(ETV6)/AML1 probe detected a fusion signal in 98% of the interphase cells. Sequential FISH on a G-banded slide showed a fusion signal on an apparently normal chromosome 12 and AML1 signals on chromosomes 21. The ETV6 was deleted from the chromosome 12 involved in the t(12;15). These results are best explained as an insertion of AML1 into TEL on one chromosome arm 12p and loss of ETV6 from the chromosome 12 involved in the t(12;15).

Child, Preschool↗
PubMed2000

IL-10 deficiency prevents IL-5 overproduction and eosinophilic inflammation in a murine model of asthma-like reaction.

Eosinophilic inflammation and bronchial mucus secretion are among the characteristic pathological changes in asthmatic reaction, which is mediated by Th2 type responses. Although it belongs to Th2 cytokines especially in the mouse, IL-10 is often considered an inhibitory cytokine for both Th1 and Th2 cells. In the present study, using a murine asthma model induced by ovalbumin (OVA), we demonstrated that endogenous IL-10 is critical for the development of asthma-like responses. Specifically, in comparison with wild-type controls, IL-10 gene knockout (KO) mice showed significantly reduced IL-5 production, eosinophilic inflammation and mucus production without notable changes in IL-4 and IgE responses following i. p. sensitization and subsequent intranasal challenge with OVA. In addition, Th1-related cytokine (IFN-gamma and IL-12) production in IL-10 KO mice was significantly higher than that in wild-type mice. The results suggest that endogenous IL-10 plays an important role in promoting pulmonary eosinophilic inflammatory reaction and mucus production during asthmatic reaction. The data also argue that IL-10 may be more influential in the development of IL-5-producing Th2 cells which differ from typical Th2 cells producing both IL-4 and IL-5.

Animals↗
PubMed2000

Oncostatin M activates stat DNA binding and transcriptional activity in primary human fetal astrocytes: low- and high-passage cells have distinct patterns of stat activation.

In this study we explored the activation of the JAK/Stat pathway by gp 130 family cytokines in primary human astrocytes. We report that of four gp 130 cytokines tested, only oncostatin M (OnM) resulted in the activation of Stat molecules. To test that the induced molecules were transcriptionally active, transcription from a Stat-responsive reporter plasmid (from the acute-phase gene alpha-2 macroglobulin) transiently transfected into astrocytes was assessed after activation by OnM and was blocked by cotransfection with dominant-negative Stat3 encoding plasmids strongly suggesting that the activation was Stat-mediated. While DNA binding complexes comprised of both Stat1 and Stat3 were induced in low-passage cells, only those containing Stat3 were formed by extracts from high-passage cells. Stat1 protein was detected in the cytoplasm of high-passage cells indicating that the inability to form SIF-B and -C complexes was due to a lack of activation of Stat1 rather than a lack of expression. These results indicate a fundamental difference between low- and high-passage astrocytes in response to cytokine treatment that might result in distinct patterns of gene expression through altered ratios of activated Stat3 and Stat1.

Astrocytes↗
PubMed2000

Expression of p53 and p21 protein in transitional mucosa adjacent to rectal carcinoma and its clinical implication.

To study the biopathological characteristics of the transitional mucosa adjacent to rectal carcinoma, 34 cases were subjected to mucin histochemical and immunohistochemical study to observe the expression of p53 and p21 protein in distal mucosa adjacent to rectal carcinoma and its relationship to the mucin change. The expression of p53 protein was found in 29.4% (10/34) of distal transitional mucosa in the cytoplasm of goblet cells, and its positive staining was within 4 cm from carcinoma margin. All p53 positive mucosa was transitional mucosa. Overexpression of p21 protein was found in 26.5% (9/34) of distal transitional mucosa in cytoplasm of crypt cells, and its positive staining was within 2 cm from carcinoma margin. There was no relationship between the expression of p53 and p21 protein in carcinoma and that in transitional mucosa (P > 0.05). These findings indicated that there was aberrant alteration of p53 and p21 genes in transitional mucosa adjacent to colorectal carcinoma, which provided further evidence that transitional mucosa was an unstable pre-cancerous change. The aberrant mucin change and genetic alteration in distal mucosa of rectal cancer is within 4 cm.

Adenocarcinoma↗
PubMed2000

Comparative study on three chemotherapeutic regimens for the treatment of advanced epithelial ovarian cancer.

To investigate the best first-line chemotherapy regimen for the treatment of advanced epithelial ovarian cancer (AEOC), the efficacy of three chemotherapy regimens for treatment of the patients with AEOC in our hospital during Jan. 1992-Jan. 1999 was retrospectively analyzed. The therapeutic effects were compared with the supplement of Melphalan + Hexamethylme (PAM + HMM), cisplatin + adriamycin + cyclophosphamide or isofamide (PAC) or cisplatin + cyclophosphamide or isofamide (PC), Taxol + cisplatin (TP) combined chemotherapy after cytoreductive surgery. The results showed that the overall effective rate of TP was significantly higher than that of PAM + HMM (P < 0.05); The complete remission rate of TP was significantly higher than that of PAM + HMM and PAC or PC (all P < 0.05); The 2-year survival rate free of tumor of TP was obviously higher than that of PAM + HMM and PAC or PC (all P < 0.05). It was concluded that the therapeutic effect of TP regimen in the treatment of AEOC was better than PAM + HMM and PAC or PC and TP regimen could be recommended currently as the preferred first-line one for the treatment of AEOC.

Adult↗
PubMed2000

Metal analysis of scales taken from Arctic grayling.

This study examined concentrations of metals in fish scales taken from Arctic grayling using laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). The purpose was to assess whether scale metal concentrations reflected whole muscle metal concentrations and whether the spatial distribution of metals within an individual scale varied among the growth annuli of the scales. Ten elements (Mg, Ca, Ni, Zn, As, Se, Cd, Sb, Hg, and Pb) were measured in 10 to 16 ablation sites (5 microm radius) on each scale sample from Arctic grayling (Thymallus arcticus) (n = 10 fish). Ca, Mg, and Zn were at physiological levels in all scale samples. Se, Hg, and As were also detected in all scale samples. Only Cd was below detection limits of the LA-ICPMS for all samples, but some of the samples were below detection limits for Sb, Pb, and Ni. The mean scale concentrations for Se, Hg, and Pb were not significantly different from the muscle concentrations and individual fish values were within fourfold of each other. Cd was not detected in either muscle or scale tissue, whereas Sb was detected at low levels in some scale samples but not in any of the muscle samples. Similarly, As was detected in all scale samples but not in muscle, and Ni was detected almost all scale samples but only in one of the muscle samples. Therefore, there were good qualitative and quantitative agreements between the metal concentrations in scale and muscle tissues, with LA-ICPMS analysis of scales appearing to be a more sensitive method of detecting the body burden of Ni and As when compared with muscle tissue. Correlation analyses, performed for Pb, Hg, and Se concentrations, revealed that the scale concentrations for these three metals generally exceeded those of the muscle at low muscle concentrations. The LA-ICPMS analysis of scales had the capability to resolve significant spatial differences in metal concentrations within a fish scale. We conclude that metal analysis of fish scales using LA-ICPMS shows considerable promise as a nonlethal analytical tool to assess metal body burden in fish that could possibly generate a historic record of metal exposure. However, comprehensive validation experiments are still needed.

Animals↗
PubMed2000

Sonographic guidance of air enema for intussusception reduction in children.

BACKGROUND: Fluoroscopically guided air reduction of intussusception is a well-accepted technique. There are only two previous reports in which US has been used to monitor pneumatic reduction. OBJECTIVE: To assess the ability of US to monitor the success of air reduction of intussusception. MATERIALS AND METHODS: Sonographically guided air-enema reduction of intussusception in 199 children. In phase I (11 children), the success or failure of reduction was confirmed by fluoroscopy. In phase II (188 children), complete reduction was confirmed by clinical improvement of the child and repeat sonography 1 h later showing no persistent intussusception. RESULTS: In phase I, fluoroscopy confirmed the accuracy of US in all 11 children. In phase II, the success rate of initial reduction was 95%. Following successful reduction, US repeated 1 h later showed no recurrence of intussusception in 92%. In ten (5%) of 188, initial reduction was unsuccessful; fluoroscopically guided air reduction successfully reduced only three of these ten failures. CONCLUSIONS: Air enema guided by US is a practical and reliable technique for the reduction of intussusception.

Air↗
PubMed2000

Mapping of centromeric regions on the molecular linkage map of rice (Oryza sativa L.) using centromere-associated sequences.

Genetic mapping of centromeres has been a challenge for plant geneticists. The objective of this study was to develop a new strategy for determining the locations of centromeric regions on genetic maps by mapping centromere-associated sequences, to make it possible to define the centromeric region of each chromosome as a single Mendelian locus on the molecular linkage map. Two DNA probes containing sequences specifically associated with the centromeres of grass species were used for genetic mapping. The centromere-associated sequences for all 12 rice chromosomes were mapped on the molecular map with either or both of the probes, and flanking molecular markers on one or both sides were localized 0 to 8 cM away. The map locations of the centromere-associated markers corresponded very well with the positions of centromeric regions determined previously using trisomic analyses for 11 of the 12 chromosomes. The precise mapping of the centromeric regions using these probes makes the molecular map a more complete and informative tool for genomic studies, which will facilitate studies of the structure and function of the rice centromeres. The simplicity of this technique, together with the fact that these probes are also associated with the centromeric regions in other grass species, may provide a general approach to the mapping of centromeric regions in the genomes of other cereal crops.

Base Sequence↗
PubMed2000

p75(NTR) mediates neurotrophin-induced apoptosis of vascular smooth muscle cells.

The development of atherosclerotic lesions results from aberrant cell migration, proliferation, and extracellular matrix production. In advanced lesions, however, cellular apoptosis, leading to lesion remodeling, predominates. During lesion formation, the neurotrophins and the neurotrophin receptor tyrosine kinases, trks B and C, are induced and mediate smooth muscle cell migration. Here we demonstrate that a second neurotrophin receptor, p75(NTR), is expressed by established human atherosclerotic lesions and late lesions that develop after balloon injury of the rat thoracic aorta. The p75(NTR), a member of the tumor necrosis factor/FAS receptor family, can modulate trk receptor function as well as initiate cell death when expressed in cells of the nervous system that lack kinase-active trk receptors. p75(NTR) expression colocalizes to neointimal cells, which express smooth muscle cell alpha-actin and are expressed by cultured human endarterectomy-derived cells (HEDC). Areas of the plaque expressing p75(NTR) demonstrate increased TUNEL positivity, and HEDC undergo apoptosis in response to the neurotrophins. Finally, neurotrophins also induced apoptosis of a smooth muscle cell line genetically manipulated to express p75(NTR), but lacking trk receptor expression. These studies identify the regulated expression of neurotrophins and p75(NTR) as an inducer of smooth muscle cell apoptosis in atherosclerotic lesions.

Animals↗