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Biomedical subjects

S Wang

Publications and source records attributed to S Wang.

At least 487 records · Page 27Linked to original sources
PubMed2000

Laboratory assessment of the status of Her-2/neu protein and oncogene in breast cancer specimens: comparison of immunohistochemistry assay with fluorescence in situ hybridisation assays.

AIM: To evaluate the clinical usefulness of three commercially available assays for Her-2/neu oncogene and protein measurements. The Her-2/neu protein is overexpressed, mostly as a result of gene amplification, in 20-30% of human breast cancers, and has been shown to have prognostic and predictive value for treatment with chemotherapy or the new monoclonal antibody, Herceptin. METHODS: An immunohistochemistry (IHC) assay using the Dako polyclonal antibody A0485, which measures the Her-2/neu protein, was compared with two new Food and Drug Administration (FDA) approved fluorescence in situ hybridisation (FISH) assays--INFORM and PathVysion, in a cohort of 52 formalin fixed, paraffin wax embedded breast tissues. These tissues were selected randomly from 84 consecutive infiltrating breast cancer specimens, which were first stratified according to the Her-2/neu protein levels as measured by IHC. RESULTS: The two FISH assays achieved a 98% concordance rate: 14 specimens (27%) showed Her-2/neu gene amplification and 37 specimens (71%) showed no Her-2/neu gene amplification. The PathVysion assay had certain advantages over the INFORM assay. In contrast, the IHC assay detected Her-2/neu overexpression in a high percentage of cases, including 13 high positive specimens (25%) and 13 medium positive specimens (25%). Although 10 of these 13 IHC high positive specimens showed gene amplification by FISH, nine of 13 IHC medium positive specimens showed no gene amplification. Statistical analyses showed that the differences between IHC and FISH assays were primarily in the specimens with medium positive IHC, but negative FISH results. CONCLUSIONS: Because of the increasing importance of the Her-2/neu oncogene and oncoprotein in the clinical management of patients with breast cancer, the accurate and consistent evaluation of Her-2/neu status is crucial. This study suggests that the best approach is to combine both IHC and FISH assays; that is, to use the IHC assay as a triage step, followed by the PathVysion FISH assay to analyse the IHC medium and high positive cases.

Biomarkers, Tumor↗
PubMed2000

The role of hydroxyl radical as a messenger in Cr(VI)-induced p53 activation.

The present study investigates whether reactive oxygen species (ROS) are involved in p53 activation, and if they are, which species is responsible for the activation. Our hypothesis is that hydroxyl radical (.OH) functions as a messenger for the activation of this tumor suppressor protein. Human lung epithelial cells (A549) were used to test this hypothesis. Cr(VI) was employed as the source of ROS due to its ability to generate a whole spectrum of ROS inside the cell. Cr(VI) is able to activate p53 by increasing the protein levels and enhancing both the DNA binding activity and transactivation ability of the protein. Increased cellular levels of superoxide radicals (O(2)(-).), hydrogen peroxide (H(2)O(2)), and.OH radicals were detected on the addition of Cr(VI) to the cells. Superoxide dismutase, by enhancing the production of H(2)O(2) from O(2)(-). radicals, increased p53 activity. Catalase, an H(2)O(2) scavenger, eliminated.OH radical generation and inhibited p53 activation. Sodium formate and aspirin,.OH radical scavengers, also suppressed p53 activation. Deferoxamine, a metal chelator, inhibited p53 activation by chelating Cr(V) to make it incapable of generating radicals from H(2)O(2). NADPH, which accelerated the one-electron reduction of Cr(VI) to Cr(V) and increased.OH radical generation, dramatically enhanced p53 activation. Thus.OH radical generated from Cr(VI) reduction in A549 cells is responsible for Cr(VI)-induced p53 activation.

Carcinogens, Environmental↗
PubMed2000

Culture and adenoviral infection of adult mouse cardiac myocytes: methods for cellular genetic physiology.

Rapid development of transgenic and gene-targeted mice and acute genetic manipulation via gene transfer vector systems have provided powerful tools for cardiovascular research. To facilitate the phenotyping of genetically engineered murine models at the cellular and subcellular levels and to implement acute gene transfer techniques in single mouse cardiomyocytes, we have modified and improved current enzymatic methods to isolate a high yield of high-quality adult mouse myocytes (5.3 +/- 0.5 x 10(5) cells/left ventricle, 83.8 +/- 2.5% rod shaped). We have also developed a technique to culture these isolated myocytes while maintaining their morphological integrity for 2-3 days. The high percentage of viable myocytes after 1 day in culture (72.5 +/- 2.3%) permitted both physiological and biochemical characterization. The major functional aspects of these cells, including excitation-contraction coupling and receptor-mediated signaling, remained intact, but the contraction kinetics were significantly slowed. Furthermore, gene delivery via recombinant adenoviral infection was highly efficient and reproducible. In adult beta(1)/beta(2)-adrenergic receptor (AR) double-knockout mouse myocytes, adenovirus-directed expression of either beta(1)- or beta(2)-AR, which occurred in 100% of cells, rescued the functional response to beta-AR agonist stimulation. These techniques will permit novel experimental settings for cellular genetic physiology.

Adenoviridae↗
PubMed2000

Bleomycin-induced pulmonary injury in mice deficient in SPARC.

SPARC (secreted protein, acidic and rich in cysteine) is a component of the matrix that appears to regulate tissue remodeling. There is evidence that it accumulates in the lung in the setting of pulmonary injury and fibrosis, but direct evidence of its involvement is only now emerging. We therefore investigated the development of pulmonary fibrosis induced by bleomycin administered either intratracheally or intraperitoneally in mice deficient in SPARC. Bleomycin (0.15 U/mouse) given intratracheally induced significantly more pulmonary fibrosis in mice deficient in SPARC compared with that in wild-type control mice, with the mutant mice demonstrating greater neutrophil accumulation in the lung. However, in wild-type and SPARC-deficient mice given intraperitoneal bleomycin (0.8 U/injection x 5 injections over 14 days), the pattern and severity of pulmonary fibrosis, as well as the levels of leukocyte recruitment, were similar in both strains of mice. These findings suggest that the involvement of SPARC in pulmonary injury is likely to be complex, dependent on several factors including the type, duration, and intensity of the insult. Furthermore, increased neutrophil accumulation in the peritoneal cavity was also observed in SPARC-null mice after acute chemical peritonitis. Together, these data suggest a possible role for SPARC in the recruitment of neutrophils to sites of acute inflammation.

Animals↗
PubMed2000

Regional variation in receptive field properties of tectal neurons in pigeons.

The present study provides the first electrophysiological evidence for dorsoventral variation in the receptive field properties of tectal cells in pigeons. According to their receptive field organization, visual response properties and laminar locations, 95 tectal neurons recorded in the present study could be categorized into two groups: (1) Fifty-five DL-neurons were recorded in the dorsal, dorso-lateral, lateral and ventro-lateral tectum and characterized by an excitatory receptive field surrounded by an inhibitory receptive field. Most of them almost equally responded to white and black objects, but did not respond to switch-on and -off of a light spot. (2) Forty VC-neurons were recorded in the ventral tectum and characterized by an excitatory receptive field alone. Their responses to switch-on of a light spot and to a white object were significantly stronger than those to light-off and to a black object, respectively. DL-neurons preferred higher velocity, whereas VC-neurons preferred lower velocity. The recording sites of 53 of 95 cells (56%) examined were marked with pontamine sky blue, showing that DL-neurons were located in tectal layers I-IV, predominantly in layer II, whereas VC-neurons were mainly concentrated in sublayer IIc. The receptive fields of VC-neurons were located within the rostroventral visual field possibly corresponding to the red field of the pigeon retina, suggesting that they might be associated with visual food-foraging behaviors.

Animals↗
PubMed2000

Promoter-based isolation and fluorescence-activated sorting of mitotic neuronal progenitor cells from the adult mammalian ependymal/subependymal zone.

Neuronal precursor cells are widespread in the subependyma of the forebrain ventricular lining, and may provide a cellular substrate for brain repair. We have previously identified and isolated them from fetal brain, by sorting forebrain cells transfected with plasmid DNA encoding the gene for green fluorescent protein (hGFP), driven by the early neuronal promoter for Talpha1 tubulin (P/Talpha1). Fetal neuronal precursors were thereby identified and harvested with both a high degree of enrichment, and a virtual abolition of glial contaminants. We have now extended this approach to include the isolation and purification of neuronal progenitors from the adult brain. Dissociates of the lateral ventricular wall, that included the combined ependymal/subependymal zone, were obtained from 3-month-old adult rats. These cells were cultured and transfected with P/Talpha1:hGFP plasmid DNA. Two days later, the cells were redissociated, sorted on the basis of Talpha1-driven GFP expression, and replated. The majority of these cells expressed the early neuronal proteins Hu and TuJ1/betaIII-tubulin upon FACS; within the week thereafter, most matured as morphologically-evident neurons, that coexpressed betaIII-tubulin and MAP-2. Fewer than 5% expressed astrocytic markers, compared to over half of the cells in matched samples that were either not sorted, or sorted after transfection with a plasmid bearing the nonfluorescent lacZ gene under the control of P/Talpha1 tubulin. Thus, the use of a fluorescent transgene under the control of an early neuron-selective promoter permits the enrichment of neuronal progenitor cells from the adult rat brain, in a form that may allow their heterologous implantation.

Animals↗
PubMed2000

Effect of fluid flow on smooth muscle cells in a 3-dimensional collagen gel model.

A 3D collagen gel model was developed to simulate interstitial fluid flow and to assess the importance of this flow on the biochemical production rates of vascular smooth muscle cells (SMCs). Rat aortic SMCs were suspended in type I collagen, and the gel was supported by nylon fibers that allowed a 9-cm length of the SMC-gel model to withstand 90 cm H(2)O differential pressure over a 6-hour period without significant compaction. Up to 1 dyne/cm(2) shear stress on the suspended SMCs could be induced by the pressure-driven interstitial flow. The suspended SMCs were globular, had a diameter of approximately 10 microm, and were distributed uniformly throughout the gel. The collagen fibers formed a network that was connected randomly with the surface of SMCs and nylon fibers. The diameter of the collagen fibers was approximately 100 nm, and the concentration of collagen was 2.5 mg/mL. Using these parameters, fiber matrix theory predicted a Darcy permeability coefficient (K:(p)) of 1.22x10(-)(8) cm(2), which was close to the measured value of K:(p). The production rates of prostaglandin (PG) I(2) and PGE(2) were used as markers of biochemical responsiveness of SMCs to fluid shear stress. Both PGI(2) and PGE(2) production rates under 1 dyne/cm(2) shear stress were significantly elevated relative to static (no-flow) controls. The production rates, however, were approximately 10 times lower than observed when the same cells were plated on collagen-treated glass slides (2D model) and exposed to the same level of shear stress by use of a rotating disk apparatus. The results indicate that interstitial flow can affect SMC biology and that SMCs are more quiescent in 3D cultures than in 2D cultures. The 3D collagen gel model should be useful for future studies of interstitial flow effects on SMC function.

Animals↗
PubMed2000

Synthesis and degradation of a tri-component copolymer derived from glycolide, L-lactide, and epsilon-caprolactone.

A series of tri-component copolymers was synthesized by ring opening copolymerization of cyclic lactones, i.e. glycolide, L-lactide, and caprolactone, using stannous octoate as a catalyst. Various techniques, including FT-IR, 1H NMR, DSC, X-ray diffraction, tensile strength, and contact angle measurements, were used to elucidate structural characteristics, thermal behavior, mechanical properties, and hydrophilicity of the resulting copolymers. Data showed that the properties of these copolymers could be modulated by adjusting the composition of the copolymers. The DSC and X-ray analysis demonstrated amorphous structures for most of the PGLC copolyesters. The degradation behavior of these PGLC copolymers had been studied in vitro, i.e. in 0.10 M pH 7.4 phosphate buffer solution (PBS). The degradation was monitored by intrinsic viscosity and weight loss measurements. SEM and GPC were also used to monitor the morphology and molecular weight change during degradation. The PGLC copolymers were shown to have variable degradation rates, and most of them could disappear within a few months due to their amorphous structure and low glass transition temperature.

Biocompatible Materials↗
PubMed2000

Adenoviral-mediated gene transfer to mouse salivary glands.

Adenoviral vectors effectively transfer genes to rat salivary glands. However, potent immune responses limit their use in vivo. Mice offer more opportunities than rats for the study of these immune processes. We first established conditions for infection of mouse salivary glands, with an adenoviral vector. The effects of time, viral dose, viral diluent buffer volume, and dexamethasone on expression of a transgene, luciferase, were determined by means of the recombinant vector AdCMVluc. Optimal luciferase expression was observed when the vector was suspended in 50 microL of buffer. This volume completely filled the gland parenchyma and slightly distended the capsule. Dexamethasone increased immediate transgene expression and reduced the acute inflammation one day following viral administration, but did not alter subsequent mononuclear inflammation or transgene expression 14 or 28 days later. An adenoviral vector encoding either anti-inflammatory cytokine IL-4 or IL-10 was co-administered with AdCMVluc to increase transgene expression at 14 and 28 days. While this strategy did not extend the duration of luciferase expression, co-administration of AdCMVIL-10 with AdCMVluc almost completely eliminated the chronic inflammatory infiltrate in the glands after 28 days. This study demonstrates that adenoviral-mediated gene transfer to mouse submandibular glands is possible by intraductal cannulation and that reduction of either the acute or chronic inflammatory infiltrates was insufficient to increase long-term transgene expression in this tissue.

Adenoviridae↗
PubMed2000

Subcellular distribution of phospholipase C isoforms in rodent pancreas and gastric mucosa.

Phosphoinositide-specific phospholipase C (PLC) has been implicated as a participant in cell proliferation as well as enzyme and hormone secretion. Defining the subcellular distribution of PLC isoforms would possibly contribute to further understanding of their function. We investigated the intracellular distribution of four PLCs (beta1, beta2, beta3, and gamma1) in mouse pancreatic cells as well as mouse and rat gastric mucosa cells by ultrastructural immunocytochemistry. In pancreatic acinar cells, PLCbeta1 and PLCgamma1 were demonstrated in the zymogen granules while PLCbeta2 was present in the granulae as well as the endoplasmic reticulum (ER), and PLCbeta3 was prominent in the ER. In the endocrine pancreas, PLCbeta2 immunolabeling was expressed in the secretory granulae of alpha, beta, delta, and pancreatic polypeptide cells. PLCbeta3 showed a slight labeling in the nucleus and ER of all four pancreatic endocrine cell types while PLCgamma1 was prominent in alpha cell granulae. In the gastric mucosa cells, PLCbeta2 was highly expressed in the heterochromatin areas and in the ER of parietal, chief, mucous, and enterochromaffin-like cells. PLCbeta3 were expressed in a manner similar to PLCbeta2 in those cells; however, no immunoreaction was seen in the ER of parietal cell. PLCgamma1 was demonstrated in the chief cell granulae. One possible, although yet speculative, interpretation of our results is that the studied PLC isoforms may be involved in processing in pancreatic secretory granulae and that nuclear PLCbeta2 and PLCbeta3 signaling pathways may be operative in the cells of the gastric mucosa.

Animals↗
PubMed2000

Brain derived neurotrophic factor is an endothelial cell survival factor required for intramyocardial vessel stabilization.

Brain derived neurotrophic factor, BDNF, is a neurotrophin best characterized for its survival and differentiative effects on neurons expressing the trk B receptor tyrosine kinase. Although many of these neurons are lost in the BDNF(-)(/)(- )mouse, the early postnatal lethality of these animals suggests a wider function for this growth factor. Here, we demonstrate that deficient expression of BDNF impairs the survival of endothelial cells in intramyocardial arteries and capillaries in the early postnatal period, although the embryonic vasculature can remodel into arteries, capillaries and veins. BDNF deficiency results in a reduction in endothelial cell-cell contacts and in endothelial cell apoptosis, leading to intraventricular wall hemorrhage, depressed cardiac contractility and early postnatal death. Vascular hemorrhage is restricted to cardiac vessels, reflecting the localized expression of BDNF and trk B by capillaries and arterioles in this vascular bed. Conversely, ectopic BDNF overexpression in midgestational mouse hearts results in an increase in capillary density. Moreover, BDNF activation of endogenous trk B receptors supports the survival of cardiac microvascular endothelial cells cultured from neonatal mice. These results establish an essential role for BDNF in maintaining vessel stability in the heart through direct angiogenic actions on endothelial cells.

Animals↗
PubMed2000

Moiré technique for spatial coherence measurements of soft-x-ray lasers.

We present a novel moiré diagnostic that allows the time-averaged spatial coherence properties of soft-x-ray lasers to be measured. The technique is an extension of the theoretical work in a recent paper [J. Opt. Soc. Am. A 16, 323 (1999)] and is based on the concept of decompositions of the far-field divergence for partially coherent beams. An appealing feature of the approach is that the spatial coherence width at other planes can be evaluated from the measured one at a given plane on the assumption of shape-invariant beams.

Computer Simulation↗
PubMed2000

9th International Conference on Obesity, NIDDM, adipogenesis and insulin resistance.

The 9th International Conference on Obesity, NIDDM, Adipogenesis and Insulin Resistance was held between 3rd and 5th April, 2000 in London, UK. The three day conference was attended by more than 100 delegates from both academic and industrial institutions. Conference topics covered the use of genetics in obesity and diabetes, etiology and implications of treatment for obesity, progress in identification of new obesity and Type 2 diabetes drug targets, islet cell targets, progress in drugs for insulin enhancement and sensitisation, adipogenesis and insulin resistance. Below are meeting highlights closely related to new drug developments and drug target identification in these therapeutic areas.

Adipose Tissue↗
PubMed2000

Secondary infections of AIDS autopsy cases in Japan with special emphasis on Mycobacterium avium-intracellulare complex infection.

In order to study the frequency of secondary infections of AIDS autopsy cases in Japan, especially the frequency of Mycobacterium aviumintracellulare complex (MAC) infection, retrospective autopsy study was conducted between 1986 and 1997 at the affiliated hospital of Institute of Medical Sciences, University of Tokyo. Secondary infections of various organs from 43 AIDS autopsy cases were examined using histopathology, genetic diagnosis of tuberculosis, Ziehl-Neelsen stain for acid-fast bacilli and immunohistochemistry. Nontuberculous mycobacterial infection (Mycobacterium avium) was observed in 17 cases (40%) out of 43 using polymerase chain reaction (PCR), but M. tuberculosis infection was not observed. Ziehl-Neelsen staining showed a positive reaction in lung and spleen tissues of 7 AIDS autopsy cases. Immunohistochemistry using anti-BCG antibody revealed positivity in 7 AIDS autopsy cases. CD4 counts of 17 AIDS patients with mycobacterial infection were less than 18.7/microl. Other opportunistic infections were also examined by histopathology. Secondary infections were present in every case, and these included cytomegalovirus infection (32 cases), Pneumocystis carinii (15 cases), Candida (16 cases), Aspergillus (12 cases), Cryptococcus (6 cases), Toxoplasma (6 cases), methicillin-resistant Staphylococcus aureus (3 cases), herpes virus (1 case) and Entamoeba histolytica (1 case). Malignant lymphoma was recognized in 14 cases and Kaposi's sarcoma in 6. This is the systemic report on secondary infections of AIDS autopsy cases in Japan. In diagnosis of mycobacterial infections, PCR was more useful than staining for acid-fast bacilli and immunohistochemistry. Secondary infections (especially mycobacterial infection) were closely associated with the low CD4 count.

AIDS-Related Opportunistic Infections↗
PubMed2000

Cost implications for the use of inhaled anti-inflammatory medications in the treatment of asthma.

OBJECTIVE: To compare the expected costs of treating patients with asthma with versus without inhaled anti-inflammatory medications, adjusting for other factors that also influence medical care expenditures. DESIGN: Nonlinear exponential regression analyses were used to estimate relationships between medical care expenditures and treatment with inhaled corticosteroids, sodium cromoglycate (cromolyn) or nedocromil. The regressions adjusted for differences in patients' demographics, location, plan type and severity of illness. SETTING: Large, self-insured, corporate-sponsored medical plans represented in MarketScan database. PATIENTS AND PARTICIPANTS: 7466 continuously enrolled patients with asthma. INTERVENTIONS: Treatment with inhaled corticosteroids, sodium cromoglycate or nedocromil. MAIN OUTCOME MEASURES: (i) Total inpatient, outpatient and pharmaceutical expenditures; and (ii) asthma-related expenditures in the 1996 calendar year. RESULTS: If all patients had been treated with inhaled anti-inflammatory drugs, total expenditures would be expected to be about $US944.82 per patient lower, on average, than would be the case if no patients received these drugs. Asthma-related expenditures would be about $US498.74 per patient higher, on average, if all patients were treated with these drugs. CONCLUSIONS: Using inhaled anti-inflammatory agents would be associated with higher asthma-related expenditures but lower total expenditures. Treatment with inhaled anti-inflammatory drugs may represent an investment in better care that pays off with better health and lower total medical care expenditures.

Administration, Inhalation↗
PubMed2000

Association between delayed cardioprotection of aged rat myocytes and activation of mitogen-activated protein kinase.

OBJECTIVE: To study the cardioprotective effects of hypoxic preconditioning (HPC) on aged rat ventricular myocytes and the cellular mechanism of protection. METHODS: In the model of hypoxia/reoxygenation (H/R) of isolated ventricular myocytes of aged rat, the effects of HPC on aged rat ventricular myocytes against lethal H/R stimulated ischemia/reperfusion (I/R) injury 24 hours later and the changes of mitogen-activated protein kinase (MAPK) system were observed in the present study. RESULTS: HPC attenuated the lactate dehydrogenase (LDH) release and ATP depletion in myocytes and increased the viability of myocytes. It was also found that MAPK and its down-stream kinase--S6 kinase were also activated after HPC. CONCLUSION: There is delayed cardioprotection in cardiac myocytes of aged rat and the cellular mechanism underlying might involve the activation of MAPK system.

Adenosine Triphosphate↗
PubMed2000

Interleukin-1beta inhibits gamma-aminobutyric acid type A (GABA(A)) receptor current in cultured hippocampal neurons.

Interleukin-1beta (IL-1beta), a polypeptide immune mediator, is induced within the central nervous system in response to a variety of pathological stimuli, including systemic infection, hypoxia, brain trauma, and seizure. IL-1beta action on the gamma-aminobutyric acid type A (GABA(A)) inhibitory neurotransmitter receptor was investigated in whole cell patch-clamped cultured hippocampal neurons. Application of IL-1beta at concentrations encountered in pathophysiological conditions (1-10 ng/ml; 59-590 pM) irreversibly decreased the peak magnitude of current elicited by 30 microM GABA. Current inhibition was IL-1beta concentration- and time-dependent and was prevented by a specific IL-1beta type I receptor antagonist. No significant changes in current kinetics or reversal potential were observed. The IL-1beta depression of GABA current was inhibited by high concentrations of nonspecific kinase inhibitors staurosporine (500 nM) and 1-(5-isoquinolinyl-sulfonyl)-2-methylpiperazine (H-7; 50 microM), but not by a protein kinase C selective inhibitor calphostin C (5 microM). We conclude that IL-1beta inhibits GABA(A) receptor function in hippocampal neurons by the involvement of an unidentified kinase. This blockade of the GABA(A) inhibitory neurotransmitter receptor may underlie the central nervous system hyperexcitability seen in many pathophysiological conditions.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗