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Biomedical subjects

S Hu

Publications and source records attributed to S Hu.

At least 379 records · Page 21Linked to original sources
PubMed1992

Effects of transforming growth factor-beta on murine astrocyte glutamine synthetase activity. Implications in neuronal injury.

Cytokines have been implicated in the pathogenesis of a number of brain diseases in which neurological dysfunction has been attributed to a change in amino acid neurotransmitter metabolism. In the present in vitro study, we investigated the effects of cytokines on astrocyte glutamine synthetase (GS) activity and subsequently on N-methyl-D-aspartate (NMDA) receptor-mediated neurotoxicity. Proinflammatory cytokines IL-1 alpha, IL-1 beta, and IL-6 at a concentration of 20 ng/ml did not affect GS activity; however, tumor necrosis factor-alpha inhibited this activity by 20% in mixed neuronal/astrocyte cultures. Treatment for 24 h with transforming growth factor (TGF)-beta 1 or -beta 2 inhibited up to 60% GS activity. TGF-beta 2 also inhibited GS in enriched astrocyte cultures with an ED50 of 10 pg/ml. Antibodies specific to TGF-beta 2 blocked this effect. Treatment of astrocytes with TGF-beta 2 (250 pg/ml) resulted in markedly dilated rough endoplasmic reticulum. Since astrocyte GS may play a protective role in NMDA receptor-mediated neurotoxicity, we treated mixed neuronal/astrocyte cultures with TGF-beta 2 (250 pg/ml) and found a threefold potentiation of NMDA receptor-mediated neurotoxicity. These data suggest that TGF-beta impairs astrocyte GS function and enhances neurotoxicity, thus providing insight into understanding one mechanism of cytokine-mediated central nervous system disease.

Animals↗
PubMed1992

Positive thinking reduces heart rate and fear responses to speech-phobic imagery.

30 speech-anxious subjects imagined a phobic speech scene 10 times. The experimental conditions varied according to whether the subjects engaged in positive, neutral, or negative thinking prior to each scene presentation. Heart rate and self-reports of fear were measured during the imagery periods. Positive thinking just before visualization of the phobic images reduced both subjective anxiety about speech and cardiovascular responses.

Adolescent↗
PubMed1992

[Establishment and preliminary application of competitive ELISA using monoclonal antibody against Trichinella spiralis].

Monoclonal antibody competitive ELISA was devised with a highly specific McAb (2G8) against T. spiralis. Among 20 rabbits infected with T. spiralis experimentally. 35% (7/20) were positive on the 17th day post infection (PI); 100% positive on the 31st day PI. No cross reaction was found with 29 sera of rabbits infected with other kinds of helminth. The dynamic antibody titer of five infected rabbits sera were studied with this method. The change may be helpful to judge the state of infection. In short, anti-T. spiralis McAb competitive ELISA can be regarded as a sensitive and specific immunological diagnostic method for T. spiralis infection.

Animals↗
PubMed1992

Effects of qingkailing on experimental allergic uveitis in rabbits.

Experimental allergic uveitis (EAU) in rabbits was induced by single intraocular injection of bovine serum albumin (BSA). The average of protein concentration in aqueous humor of untreated group of rabbits was 14.33 +/- 1.21 mg/ml and the count of tritiated thymidine (3H-TdR) incorporated into lymphocyte T was 3,987 +/- 1,156cpm/10(6). The specific antibody responses to BSA in the serum and the aqueous were 0.508 +/- 0.034 and 0.369 +/- 0.019 (OD) respectively. Meanwhile, the effect of Qingkailing on EAU was observed in comparison with dexamethasone as the positive control. The inflammatory reactions of rabbits treated with Qingkailing were remarkably diminished clinically and pathologically. The amount of protein concentration in aqueous of the treated rabbits was 5.79 +/- 2.19 mg/ml (P < 0.01) and the count of 3H-TdR incorporation was 2,455 +/- 981cpm/10(6) (P < 0.05). The responses of antibody in the serum and the aqueous were 0.414 +/- 0.059 and 0.253 +/- 0.041 (P < 0.01) respectively. Our observations indicate that Qingkailing has a positive therapeutic effect on EAU in the rabbits and sustain the suggestion that this drug is capable of suppressing immune and phlogistic reactions.

Animals↗
PubMed1992

[3H]2-phenylaminoadenosine ([3H]CV 1808) labels a novel adenosine receptor in rat brain.

Earlier studies have demonstrated that the vasoactive compound CV 1808 displays 10-fold selectivity for the adenosine A2 receptor, and as such, was the first reported A2-selective agonist. After the radiolabeling of CV 1808, its binding characteristics were evaluated in rat striatal, cortical and hippocampal membranes. Using 5 nM [3H]CV 1808, unlabeled CV 1808 produced shallow inhibition curves in all three brain areas, with 61 to 75% of the binding displaying IC50 values of 16 to 24 nM, whereas the remaining 28 to 37% of binding had lower affinity (IC50 595-1130 nM). The A2-selective agonist CGS 21680 and the nonselective adenosine agonist 5'-N-ethylcarboxamidoadenosine displayed very low affinity (IC50 > 10 microM). The A1-selective compound N6-cyclopentyladenosine inhibited only 28 to 44% of specific binding, with IC50 of 272-1750 nM. In contrast, the nonselective adenosine antagonist CGS 15943A inhibited specific binding by 48 to 64% (at 1 microM) with IC50 ranging from 106 to 295 nM. Additionally, several novel adenosine analogs fully inhibited specific binding, producing multicomponent inhibition curves. Electrophysiological studies in porcine coronary artery cells demonstrated that CV 1808, but not CGS 21680, 5'-N-ethylcarboxamidoadenosine and N6-cyclopentyladenosine, activated potassium channels. Further, the CV 1808-induced activation was blocked by CGS 15943A. These results indicate that [3H]CV 1808 binding consists of two components in rat brain: a low-affinity site with A1-like characteristics, and a novel high-affinity site, designated as the A4 receptor, where potassium channel activation appears to be a functional correlate.

Adenosine↗
PubMed1992

[The use of 6-flavor Rehmannia decoction with additives in the prevention of ototoxic deafness induced by gentamicin in guinea pigs].

The purpose of this study is to discuss the effects of the Chinese medicine six-flavor Rehmannia Decoction with additives on preventing deafness induced by gentamicin (GM) in guinea pig by means of testing the thresholds of Preyer's reflex (PR) cochlear microphonic potential (CM), action potential of the auditory nerve (N1) and scanning electron microscope of inner ear (SEM). The results showed that the medicine is effective in reducing the ototoxic effect of GM on inner ear.

Action Potentials↗
PubMed1992

[An animal model of posttraumatic multiple system organ failure (MSOF)].

Hemorrhagic shock, sepsis, excessive systemic inflammatory reactions, and failure of intestinal mucosal barrier function are known to be major predisposing factors in the development of MSOF in patients after severe trauma or burns. We investigated the possibility of complicating clinically simulating MSOF in animals. Our results showed that, with compounded traumatic factors, including damages to the bowel, and proper circulatory and respiratory support, an animal model which simulated the pathophysiology and histopathology of MSOF could be reproduced to offer opportunity for the study of mechanisms and therapy. Markers of MSOF were also described for reference.

Animals↗
PubMed1992

Morphine potentiates transforming growth factor-beta release from human peripheral blood mononuclear cell cultures.

Opiates modulate a variety of immune responses by peripheral blood mononuclear cells (PBMC). In the present study, we investigated the effect of morphine on the release of several cytokines upon stimulation with mitogens. An interleukin (IL)-4-dependent HT-2 cell proliferation assay was used to quantify transforming growth factor-beta (TGF-beta). IL-6 and tumor necrosis factor-alpha (TNF-alpha) were measured by enzyme-linked immunosorbent assays. Morphine (1 pM and 10 nM) alone did not significantly modulate the release of TGF-beta, IL-6 or TNF-alpha. Upon stimulation with lipopolysaccharide and phytohemagglutinin, PBMC released more (P less than .01) TGF-beta, IL-6 and TNF-alpha than unstimulated PBMC. Exposure of PBMC to morphine (1 pM) for 24 hr substantially amplified (P less than .05) the release of TGF-beta in the following 24 hr incubation period. Morphine did not alter the release of immunodetectable IL-6 or TNF-alpha from stimulated cells. The amplifying effect of morphine on the release of TGF-beta was mediated through a naloxone-sensitive mechanism. Given the fact that TGF-beta has a potent immunosuppressive effect, morphine-potentiated release of TGF-beta from PBMC may be involved in the immunomodulatory activity ascribed to morphine.

Adult↗
PubMed1991

A copper-thiolate polynuclear cluster in the ACE1 transcription factor.

ACE1 is the transcriptional activator of the metallothionein (CUP1 locus) gene in Saccharomyces cerevisiae. Previous data had implicated the N-terminal domain of ACE1 as responsible for the Cu-dependent specific DNA binding. An expression system in Escherichia coli was constructed to enable the isolation of an ACE1 domain containing the DNA and Cu-binding regions. Here we report the purification and characterization of the Cu-ACE1 truncated molecule. Spectroscopic techniques showed that ACE1 contains an unusual type of DNA binding structure that is based on a polynuclear Cu(I)-cysteinyl thiolate cluster. The cluster consists of six or seven Cu(I) ions coordinated to cysteinyl thiolates in a trigonal geometry distorted from planarity. The Cu(I)-cysteine cluster of Cu-ACE1 exhibits structural properties analogous to the Cu(I)-thiolate polynuclear cluster in yeast Cu-metallothionein itself, suggesting an unusual mechanism for the evolution of this regulatory factor. The Cu cluster organizes and stabilizes the conformation of the N-terminal domain of ACE1 for specific DNA binding.

Amino Acid Sequence↗
PubMed1991

Spectroscopic characterization of the copper(I)-thiolate cluster in the DNA-binding domain of yeast ACE1 transcription factor.

A polypeptide containing the amino-terminal region of ACE1 (residues 1-122; 122*), the activator of yeast Cu-metallothionein gene transcription, shows charge-transfer and metal-centered UV absorption bands, and orange luminescence which are characteristic of Cu-cysteinyl thiolate cluster structures. These spectral features are abolished by the Cu(I) complexing agents CN- and diethyldithiocarbamate or exposure to acid, but not by the Cu(II) chelator, EDTA. Binding of the polypeptide to its specific DNA recognition site, but not to calf-thymus double-stranded DNA, induces quenching of its Tyr and Cu-S cluster luminescence emission. The CD spectrum is characteristic of a tightly folded structure that may be organized around the Cu cluster.

Amino Acid Sequence↗
PubMed1991

Study on multiple-enzyme electrode for sucrose determination.

Invertase (INV), mutarotase (MUT), glucose oxidase (GOD) and BSA were coimmobilized via glutaraldehyde-bridged covalent bonding, and directly absorbed on the teflon membrane. This membrane was covered with a nylon mesh and placed over an oxygen electrode. An enzyme electrode for flow injection analysis system (EFIA) was adopted. The optimum enzyme composition (IU) for immobilization on the teflon membrane of INV-MUT-GOD was found to be in the ratio 72:48:2.4, with a recovery activity INV-MUT of more than 42.9%. pH 5.8-6.5 was the most suitable range of acidity for the sensor activity. The optimum temperature was 35-45 degrees C. The system exhibited good linearity in the range of 5 x 10(-4) approximately 10(-1) M sucrose (kinetic method) and 10(-5) approximately 2 x 10(-3) M sucrose (steady state method), in short response time (20 seconds for kinetic method, 2 minutes for steady state method), CV = 1.7% (kinetic method). The sensor had been used for determining sucrose concentration in fermentation broth, with an average recovery rate of 98%. The interference caused by the presence of glucose derived from decomposition of sucrose was eliminated by calibration with a GOD sensor. No significant loss of the enzyme electrode activity was observed after 120 hours of the continuous flow of fresh 1 mM sucrose. The multiple-enzyme membrane showed a relatively long lifetime (compared with 14 hours as reported previously) and good storage stability (30 days, stored in distilled water at 4 degrees C).

Biosensing Techniques↗
PubMed1991

Varus rotational femoral osteotomies in adults with hip dysplasia.

Fifty-six hips in 48 consecutive patients operated on for congenital dysplasia of the hip during the years 1971 through 1986 were evaluated for an average follow-up period of nine years (range, two-21 years). Twenty-three percent of the patients were treated with revision to total hip arthroplasty by the time of follow-up examination. The average time before revision was 8.6 years. All but three of the remaining hips were rated good or excellent (72%). These patients tended to have minimal or no preoperative degenerative joint disease. Complications included one subtrochanteric fracture, two cases of loss of fixation, and one superficial wound infection. The authors conclude that the operation provides predictable, high-quality results in those patients with minimal or no degenerative changes preoperatively. In those patients with mild or moderate degenerative changes, it may forestall the onset of severe symptoms by several years.

Adolescent↗
PubMed1991

Motion sickness severity and physiological correlates during repeated exposures to a rotating optokinetic drum.

Fifty-two subjects were exposed to a rotating optokinetic drum. Ten of these subjects who became motion sick during the first session completed two additional sessions. Subjects' symptoms of motion sickness, perception of self-motion, electrogastrograms (EGGs), heart rate, mean successive differences of R-R intervals (RRI), and skin conductance were recorded for each session. The results from the first session indicated that the development of motion sickness was accompanied by increased EGG 4-9 cpm activity (gastric tachyarrhythmia), decreased mean successive differences of RRI, increased skin conductance levels, and increased self-motion perception. The results from the subjects who had three repeated sessions showed that 4-9 cpm EGG activity, skin conductance levels, perception of self-motion, and symptoms of motion sickness all increased significantly during the drum rotation period of the first session, but increased significantly less during the following sessions. Mean successive differences of RRI decreased significantly during the drum rotation period for the first session, but decreased significantly less during the following sessions. In conclusion, we have demonstrated that the development of motion sickness is accompanied by an increase in gastric tachyarrhythmia, and an increase in sympathetic activity and a decrease in parasympathetic activity, and that adaptation to motion sickness is accompanied by the recovery of autonomic nervous system balance.

Adaptation, Physiological↗
PubMed1990

The single-minded gene of Drosophila is required for the expression of genes important for the development of CNS midline cells.

The single-minded (sim) gene of Drosophila encodes a nuclear protein that plays a critical role in the development of the neurons, glia, and other nonneuronal cells that lie along the midline of the embryonic CNS. Using distinct cell fate markers, we observe that in sim mutant embryos the midline cells fail to differentiate properly into their mature CNS cell types and do not take their appropriate positions within the developing CNS. We further present evidence that sim is required for midline expression of a group of genes including slit, Toll, rhomboid, engrailed, and a gene at 91F; that the sim mutant CNS defect may be largely due to loss of midline slit expression; and that the snail gene is required to repress sim and other midline genes in the presumptive mesoderm.

Animals↗
PubMed1990

The effect of worry on cardiovascular response to phobic imagery.

Cardiovascular response to phobic exposures has been shown to reflect the degree of emotional processing of phobic material and relates in important ways to outcome in exposure therapy. The present study investigated the effect of worry on such processing. Speech anxious subjects visualized a phobic scene for 10 trials. Three groups differed according to whether they engaged in relaxed, neutral, or worrisome thinking just prior to each scene presentation. Although the three types of thinking had no effect on cardiovascular activity during the thinking periods, subjects in the worry group displayed significantly less heart rate response to the phobic image than those in the neutral condition who had significantly less response than the relaxed condition. However, the worry group showed significantly greater subjective fear to the images than the neutral condition, with the relaxed group near to the level of the worry group and not significantly different from either of the other two conditions. The results suggest that worry may inhibit emotional processing and thus preserve cognitive/affective fear structure, and are discussed in terms of Gray's (Behavioral and Brain Sciences, 5, 469-534, 1982) theory of the behavioral inhibition system and semantic satiation effects in cognitive psychology.

Adolescent↗