Biomedical subjects

S Hu

Publications and source records attributed to S Hu.

At least 361 records · Page 20Linked to original sources

PubMed1993

Chinese hyper-susceptibility to vection-induced motion sickness.

Little is known about the factors that control individual differences in susceptible to motion sickness. A serendipitous observation in our laboratory that most Chinese subjects become motion sick prompted this study. We used a rotating optokinetic drum to provoke motion sickness and compared gastric responses and symptom reports of Chinese, European-American, and African-American subjects. There was no difference in the responses of European-American and African-American subjects; however, Chinese subjects showed significantly greater disturbances in gastric activity and reported significantly more severe symptoms. We suggest that this hyper-susceptibility presents a natural model for the study of physiological mechanisms of nausea and other symptoms of motion sickness.

Adult↗

PubMed1993

[Effect of superoxide dismutase on experimental allergic uveitis].

In this study, experimental allergic uveitis (EAU) in guinea pigs was induced by an injection of bovine serum albumin (BSA) into the vitreous after having pre-immunized them intradermally with BSA plus incomplete Freund adjuvant, and the effect of superoxide dismutase (SOD) on EAU was observed. The result showed that, histopathologically, the phlogistic cell infiltration and exudation within the anterior ocular part of the SOD- treated animals reduced notably. It is suggested that SOD which can scavenge the free radical superoxide anion may alleviate the cellular reaction in the pathological process of uveitis.

Animals↗

PubMed1993

Hemodynamic and nonhemodynamic mechanisms of experimental pulmonary edema in rats and the effect of anisodamine and tetramethylpyrazine. Part 1: Survival rate, pulmonary index, pathological change and pulmonary vascular permeability.

Pulmonary edema (PE) which is similar to the neurogenic type was induced by adrenaline (AD) administration (0.1 mg/kg) in rats. Acute progressive respiratory distress, cyanosis and dyspnea occurred. All the experimental animals in the PE group died within 20 min after AD injection, with a pulmonary index (PI) of 1.70 +/- 0.47 (mean +/- S) which was much higher than that in the normal group. The mortality rate was 100%. It was found that in rats with PE, a protein-rich fluid filled the alveolar and interstitial spaces, and ecchymosis occurred. The capillary permeability as estimated by Evans blue injection showed that Evans blue from extraction fluid and bronchoalveolar lavage (BAL) in the PE rats was at a much higher level than that in the normal control (NC) rats. In anisodamine (ADM, 654-2) and tetramethylpyrazine (TMP) treated rats, almost all the damage was diminished or absent, and the mortality rates were decreased from 100% to 4.4% and 20%, respectively. 654-2 and TMP could significantly inhibit the increase of pulmonary permeability.

Animals↗

PubMed1992

Resonance Raman studies of the carbonmonoxy form of catalase. Evidence for and effects of phenolate ligation.

Resonance Raman spectra are reported for the carbon monoxide (CO) adduct of catalase formed from the reaction of peracetic acid or hydrogen peroxide with the azide adduct of catalase in the presence of CO. The expected three normal vibrations of the FE-CO fragment are detected at 1,908,593 and 543 cm-1 for the nu(C-O), delta(Fe-C-O) and nu(Fe-CO), respectively. The expected coordination of the phenolate group in this adduct is confirmed by the enhancement of an internal vibration of phenolate, nu 19a at 1,515 cm-1, and an extraordinary intensity enhancement of the nu(Fe-CO) mode.

Carbon Monoxide↗

PubMed1992

Activated microglia mediate neuronal cell injury via a nitric oxide mechanism.

Activated microglial have been proposed to play a pathogenetic role in immune-mediated neurodegenerative diseases. To test this hypothesis, purified murine neonatal microglial were cocultured with neuronal cells derived from fetal brain. Activation with IFN-gamma and LPS of these cocultures brought about a sharp decrease in uptake of gamma-amino butyric acid and a marked reduction in neuronal cell survival. These effects varied with the density of microglia, the concentrations of the activation signals (IFN-gamma and LPS), and the duration of coculture. Inasmuch as addition of NG-monomethyl-L-arginine blocked these effects, a L-arginine-dependent neurocytotoxic mechanism was implicated. Abundant nitrite, a metabolite of the free radical nitric oxide (NO) derived from L-arginine, was detected in activated microglial/neuronal cell cocultures and in purified microglial cell cultures but not in purified astrocyte or neuronal cell cultures, suggesting that microglial were the principal source of the NO. These findings support the hypothesis that microglia are the source of a neurocytotoxic-free radical, and shed light on an additional mechanism of immune-mediated brain injury.

Amino Acid Oxidoreductases↗

PubMed1992

Support of human hematopoiesis in long-term bone marrow cultures by murine stromal cells selectively expressing the membrane-bound and secreted forms of the human homolog of the steel gene product, stem cell factor.

The maintenance and differentiation of hematopoietic stem cells is influenced by cells making up the hematopoietic microenvironment (HM), including bone marrow-derived stromal cells. We and several other investigators have recently demonstrated the molecular basis of abnormal HM observed in the steel mutant mouse and cloned the normal cDNA products of this gene (termed SCF, KL, or MCF). In this report, we focus on the human counterpart of the mouse Steel (Sl) gene. Alternative splicing of the human SCF pre-mRNA transcript results in secreted and membrane-bound forms of the protein. To investigate the role of these two forms of human SCF, we targeted an immortalized stromal cell line derived from fetal murine homozygous (Sl/Sl) SCF-deficient embryos for gene transfer of various human cDNAs encoding SCF. We report that stable stromal cell transfectants can differentially process the two forms of human SCF protein product. We also demonstrate that both soluble SCF and membrane-bound SCF are active in increasing the number of human progenitor cells in the context of stromal cell cultures, although in a qualitatively different manner. Hence, the membrane-bound form of SCF may play an important role in the cell-cell interactions observed between stromal and hematopoietic cells both in vitro and in vivo.

Amino Acid Sequence↗

PubMed1992

Characterization of the copper- and silver-thiolate clusters in N-terminal fragments of the yeast ACE1 transcription factor capable of binding to its specific DNA recognition sequence.

N-terminal fragments of ACE1 protein spanning residues 1-122 or 1-110, termed ACE1(122*) and ACE1(110*), respectively, were investigated in regard to their metal- and double-stranded DNA-binding properties. Band mobility shift assays showed that binding to a specific oligonucleotide (termed UASc), containing two ACE1(122*) binding sites, requires the presence of Cu(I) or Ag(I) but does not occur in the presence of divalent metal ions. Both the Ag(I) and the Cu(I) forms of ACE1(122*) were characterized spectroscopically. The Tyr and metal cluster luminescence emission of Cu-ACE1(122*) was specifically quenched by the oligonucleotide UAScL, but not by an oligonucleotide of the same length and base composition but scrambled sequence. The room-temperature luminescence of Cu(I)-ACE1(122*) was assigned to a phosphorescence emission, on the basis of its long-lived luminescence of approximately 3.5 microseconds. We report the first observation of a Ag(I) metal cluster in solution for Ag(I)-ACE1(122*), which was found to exhibit a quantum yield and average luminescence lifetime that are ca. 6% of that of Cu(I)-ACE1(122*). The three-dimensional structure brought about by the binding of either metal ion appears to be very similar, since dynamic tyrosine fluorescence lifetime measurements, as well as circular dichroism spectra, were nearly identical for Cu- and Ag-ACE1(122*). Based on these results, we present a hypothetical model for the structure of the metal cluster in this class of proteins.

Base Sequence↗

PubMed1992

Neu differentiation factor: a transmembrane glycoprotein containing an EGF domain and an immunoglobulin homology unit.

We recently reported that a 44 kd glycoprotein secreted by transformed fibroblasts stimulates tyrosine phosphorylation of the product of the neu proto-oncogene and induces differentiation of mammary tumor cells to milk-producing, growth-arrested cells. A partial amino acid sequence of the protein, termed Neu differentiation factor (NDF), enabled cloning of the corresponding complementary DNA. The deduced structure of the precursor of NDF indicated that it is a transmembrane protein whose extracellular portion contains an EGF-like domain that probably functions as a receptor recognition site. In addition, the ectodomain contains one immunoglobulin homology unit. Despite the lack of a recognizable hydrophobic signal peptide at the N-terminus, a recombinant NDF, like the natural molecule, is released into the medium of transfected COS-7 cells in a biologically active form. Northern blot analysis indicated the existence of several NDF transcripts, the major ones being 1.8, 2.6, and 6.7 kb in size. Transformation by the ras oncogene dramatically elevated the expression of NDF in fibroblasts.

Amino Acid Sequence↗

PubMed1992

Drosophila single-minded gene and the molecular genetics of CNS midline development.

Our goal is to understand the molecular mechanisms that govern the formation of the central nervous system. In particular, we have focused on the development of a small group of neurons and glia that lie along the midline of the Drosophila CNS. These midline cells possess a number of unique attributes which make them particularly amenable to molecular, cellular, and genetic examinations of nervous system formation and function. In addition, the midline cells exhibit distinctive ontogeny, morphology, anatomical position, and patterns of gene expression which suggest that they may provide unique functions to the developing CNS. The single-minded gene encodes a nuclear protein which is specifically expressed in the midline cells and has been shown to play a crucial role in midline cell development and CNS formation. Genetic experiments reveal that sim is required for the expression of many CNS midline genes which are thought to be involved in the proper differentiation of these cells. In order to identify additional genes which are expressed in some or all of the midline cells at different developmental stages, a technique known as enhancer trap screening was employed. This screen led to the identification of a large number of potential genes which exhibit various midline expression patterns and may be involved in discrete aspects of midline cell development. Further molecular, genetic, and biochemical analyses of sim and several of the enhancer trap lines are being pursued. This should permit elucidation of the genetic hierarchy which acts in the specification, differentiation, and function of these CNS midline cells.

Animals↗

PubMed1992

A randomized comparative trial of the MLCu375, TCu220C, steel ring and uterine cavity-shaped IUDs.

The Stainless Steel Ring, Uterine Cavity-Shaped Device, TCu220C and MLCu375 IUDs were evaluated in a randomized trial of 1536 women in Guangdong Province, China. The first-year continuation and expulsion rates were significantly lower (p less than 0.05) for the latter 3 IUDs than for the Stainless Steel Ring. The first year pregnancy rates for the MLCu375 (0.76 per 100 women) and TCu220C (1.2 per 100 women) were significantly lower (p less than 0.05) than those of the other two devices (6.1 and 4.1 per 100 women). The results of the study show that the MLCu375 and TCu220C are the most suitable IUDs for women in Guangdong Province.

Adult↗

PubMed1992

Glioblastoma, transforming growth factor-beta, and Candida meningitis: a potential link.

The development of Candida meningitis in a patient following partial resection of a glioblastoma raised suspicion that transforming growth factor (TGF-beta), an immunosuppressive cytokine known to be produced by this tumor, would be elevated in his cerebrospinal fluid (CSF). By using a highly specific bioassay, the concentration of TGF-beta was found to be 609 pg/mL, which was 10-fold greater than the mean CSF TGF-beta value in control subjects with no neurologic disease. Increased CSF TGF-beta levels were also detected in patients with other central nervous system (CNS) diseases: malignancies and AIDS dementia complex. These findings suggest that TGF-beta may play an immunopathogenetic role in the CNS.

Acquired Immunodeficiency Syndrome↗

PubMed1992

Electrical acustimulation relieves vection-induced motion sickness.

The aim of this study was to examine the effects of electrical acustimulation on gastric myoelectric activity and severity of symptoms of motion sickness. In experiment 1, 16 Chinese subjects received electrical acustimulation in one of two sessions. In experiment 2, 45 white and black American subjects were randomly divided into three groups: acustimulation, sham acustimulation, and control. Each subject sat in an optokinetic drum for 15 minutes baseline and 15 minutes of drum rotation. Subjects' electrogastrograms and subjective symptoms of motion sickness were obtained. In experiment 1, the mean symptom score and tachyarrhythmia during acustimulation sessions were significantly lower than during no-acustimulation sessions. In experiment 2, the mean symptom score of the acustimulation group was significantly lower than that of the sham-stimulation group and the control group; tachyarrhythmia in the acustimulation group was significantly less than that of the control group but not the sham-stimulation group. In conclusion, electrical acustimulation reduces the severity of symptoms of motion sickness and appears to decrease gastric tachyarrhythmia.

Adult↗

PubMed1992

Immunologically mediated fatigue: a murine model.

Chronic fatigue syndrome (CFS) is an idiopathic disorder in which the chief symptoms is profound fatigue. To explore the relationship between immune stimulation and fatigue, we developed a murine model for quantifying fatigue: reduction in voluntary running and delayed initiation of grooming after swimming. Inoculation of female BALB/c mice with Corynebacterium parvum antigen or the relatively avirulent Me49 strain of Toxoplasma gondii induced fatigue: baseline running reduced to less than 50 and 30% for 8 and 14 days, respectively, and delayed initiation of grooming after swimming in both immunologically stimulated groups. A threefold evaluation of serum transforming growth factor-beta levels, a cytokine increased in CFS patients, was found in fatigued C. parvum- and T. gondii-inoculated mice. This murine model appears promising for investigation of the pathogenesis of immunologically mediated fatigue.

Animals↗

PubMed1992

Microglial cell upregulation of HIV-1 expression in the chronically infected promonocytic cell line U1: the role of tumor necrosis factor-alpha.

Culture supernatants from lipopolysaccharide (LPS)-treated murine microglial cells were found to markedly induce the expression of human immunodeficiency virus (HIV)-1 in the chronically infected human promonocytic cell line U1 as detected by measurements of HIV-1 p24 antigen release into U1 culture supernatants. Antibody to tumor necrosis factor (TNF)-alpha had an inhibitory effect on the induction of virus by microglial cell supernatants. Also, treatment of microglia with pentoxifylline, an inhibitor of TNF-alpha production, resulted in suppressed amounts of TNF in the supernatants of LPS-treated microglia and in a reduced stimulatory capacity of these supernatants on HIV-1 expression in U1 cells. These findings support the concept that TNF-alpha production by glial cells plays a pathogenetic role in HIV-1-associated brain disease by promoting the expression of the virus in infected cells.

AIDS Dementia Complex↗

PubMed1992

Neuroprotective effects of graded reoxygenation following chronic hypoxia in neuronal cell cultures.

The present study was undertaken to investigate the comparative effects of rapid vs graded correction of chronic hypoxia in vitro. Cerebral cortical cell cultures obtained from fetal mice were exposed to 5% O2 for 24 h and returned immediately to room air for the following 24 h (Group I); comparable cultures were exposed to 5% O2 for 24 h followed by 10% O2 for an additional 24 h before return to room air (Group II). At the conclusion of the experimental protocol (time 0), partial pressure of oxygen in the bathing medium of Group I cultures was significantly higher than that of Group II and non-hypoxic controls (151 mmHg vs 124 and 132 mmHg, respectively; P less than 0.05). Throughout the recovery period, Group II cultures evidenced improved neuronal survival (e.g. 35,800 vs 17,700 neurons/culture well at time 0, P less than 0.01), decreased lactate dehydrogenase efflux into the bathing medium, relative preservation of neuronal morphology, as well as higher specific and clonazepam-displaceable benzodiazepine binding and GABA uptake. Glutamate binding was not differentially affected and glutamine synthetase activity, a predominantly glial marker, was only modestly increased after graded reoxygenation. These results demonstrate that gradual reoxygenation after prolonged hypoxia in vitro (i) improves neuronal survival compared to rapid reoxygenation and (ii) delays the manifestations of metabolic dysfunction even though the length of hypoxic exposure is increased. The findings are also consistent with the concept that a period of relative hyperoxia may contribute to hypoxia-induced neuronal injury.

Animals↗

PubMed1992

Determination of trace amounts of estriol and estradiol by adsorptive cathodic stripping voltammetry.

Estriol and estradiol are electroinactive in the potential range from -200 to -1000 mV versus a silver-silver chloride electrode at a mercury electrode. The conversion of these estrogens into electroactive nitro derivatives of estrogens, which are used for voltammetric determination, was studied. Such nitro derivatives give a well defined cathodic stripping wave at -600 mV in pH 10.5 borate buffer. Estriol and estradiol are determined in the ranges 1 x 10(-9)-1.5 x 10(-6) and 5 x 10(-9)-2 x 10(-6) mol dm-3, respectively, by differential-pulse adsorptive stripping voltammetry at a hanging mercury drop electrode. Some steroids, such as estrone, interfere because the three estrogens have almost the same molecular structure and have similar nitro derivatives, but progesterone does not interfere and is reduced at significantly more negative potentials than the nitrated estrogens. It can be determined simultaneously with estriol or estradiol. A method was developed for the assay of estriol in pharmaceutical preparations.

Adsorption↗

PubMed1992

Cytokine release from microglia: differential inhibition by pentoxifylline and dexamethasone.

Cytokines have been implicated in the pathogenesis of gram-negative bacterial meningitis. The effects of pentoxifylline and dexamethasone on the release of tumor necrosis factor (TNF), interleukin (IL)-1, and IL-6 from primary murine microglial cell cultures were explored using bioassays. When added concomitantly with lipopolysaccharide, pentoxifylline blocked the release of TNF and IL-1 but not IL-6, while dexamethasone inhibited the release of TNF and IL-6. After a 2-h exposure of microglia to lipopolysaccharide, pentoxifylline but not dexamethasone still inhibited the release of TNF. Release of TNF was enhanced 20-fold by priming of the microglia with interferon-gamma; only pentoxifylline blocked the priming effect of interferon-gamma on TNF release. These results demonstrate that pentoxifylline and dexamethasone differentially regulate the release of cytokines in microglial cell cultures and provide potential insight into their role in the treatment of gram-negative bacterial meningitis.

Animals↗

PubMed1992

Influence of medicinal herbs on phagocytosis by bovine neutrophils.

Twenty-six herbal preparations made from 24 medicinal herbs, categorized as antipyretics in Chinese materia medica, were tested in vitro to determine their effects upon phagocytosis of 32P-labelled Staphylococcus aureus by neutrophils isolated from bovine blood and milk. The percentage of phagocytosis was determined after incubating (1 hour at 37 degrees C) 1.25 x 10(7) neutrophils, 1 x 10(8) 32P-labelled S. aureus and 10% skimmed milk with herbal solutions. Concentrations of herbal preparations tested were 100%, 10% and 1% (v/v). When compared with PBSS (0.01 M phosphate buffered saline solution) controls, most of the herbs at high concentrations inhibited phagocytosis while at lower concentrations phagocytosis was increased. All 26 herbal preparations significantly increased blood neutrophil activity at their proper concentrations. The most active herbs in promoting blood neutrophil phagocytosis were observed for Herba verbenae, Flos chrysanthemi, Flos lonicerae, Radix sophorae flavescentis, Herba houttuyniae, Radix isatidis, Herba patriniae, Berberini sulfatis at the lowest concentration and for Folium hibisci at the high concentration with the increased percentage of more than 40.0% in comparison with PBSS control. Of the 19 herbal preparations tested with milk neutrophils, 18 herbs greatly increased phagocytosis at suitable concentrations. The most active preparations in stimulating milk neutrophil functions included Folium hibisci, Flos chrysanthemi, Radix bupleuri, Radix stellariae, Herba houttuyniae, Herba senecionis scandentis, Caulis lonicerae and Flos lonicerae which increased phagocytosis by over 35.0%.

Animals↗