Biomedical subjects

X Huang

Publications and source records attributed to X Huang.

At least 631 records · Page 35Linked to original sources

PubMed1993

5-HT2 receptor-mediated potentiation of dopamine synthesis and central serotonergic deficits.

The hypothesis was tested that serotonin (5-HT) modulates 3,4-methylenedioxymethamphetamine (MDMA)-induced increase in dopamine synthesis. Rats were treated with the selective 5-HT2 receptor agonist (R)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (R-DOI), the selective serotonin releasing agent 5-methoxy-6-methyl-2-aminoindan (MMAI), amphetamine, MDMA, or a combination of amphetamine and R-DOI or MMAI, followed by the L-dihydroxyphenylalanine (DOPA) decarboxylase inhibitor 3-hydroxybenzylhydrazine (NSD-1015). Rats were killed 45 min after the first injection and striatal DOPA was determined. R-DOI, MMAI, or amphetamine alone did not increase DOPA accumulation. However, combination of amphetamine with either MMAI or R-DOI significantly increased DOPA accumulation. Multiple doses of the R-DOI and amphetamine combination did not decrease [3H]paroxetine binding sites at one week after killing. The results indicate that the dopamine synthesis increasing effect of MDMA depends both on 5-HT2 receptor stimulation and dopamine efflux.

3,4-Methylenedioxyamphetamine↗

PubMed1993

Purification and sequence determination of heat-stable enterotoxin elaborated by a cholera toxin-producing strain of Vibrio cholerae O1.

Four molecular species of heat-stable enterotoxins elaborated by a cholera toxin-producing strain of Vibrio cholerae O1 were isolated from its culture supernatant. The amino acid sequence of one of the enterotoxins was determined to be Phe-Ile-Lys-Gln-Val-Asp-Glu-Asn-Gly-Asn-Leu-Ile-Asp-Cys-Cys-Glu-Ile-Cys- Cys-Asn-Pro-Ala-Cys-Phe-Gly-Cys-Leu-Asn with three intramolecular disulfide linkages. The other enterotoxins had shorter amino acid sequences in the N-terminal regions, but possessed the same sequence in their C-terminal regions including the three disulfide linkages. The enterotoxins with the shorter N-terminal sequences showed more potent toxicities, and the minimum effective dose of the longest one with 28 amino acid residues was 10-folds of that of the shortest one.

Amino Acid Sequence↗

PubMed1993

Leukocyte extravasation into the pancreatic tissue in transgenic mice expressing interleukin 10 in the islets of Langerhans.

Transgenic expression of interleukin 10 (IL-10) in the islets of Langerhans leads to a pronounced pancreatic inflammation, without inflammation of the islets of Langerhans and without diabetes. A scattered infiltration of macrophages (M pi) precedes localized accumulations of CD4+ and CD8+ T lymphocytes, B lymphocytes, and M pi. This recruitment of inflammatory cells to the pancreas is somewhat surprising, since the biological activities of IL-10 in vitro indicate that IL-10 is a powerful immunosuppressive cytokine. Since endothelial cells play a major role in leukocyte extravasation, we examined if vascular changes and extralymphoid induction of peripheral and mucosal type vascular addressins contributed to IL-10-induced homing of mononuclear cells to the pancreas. The endothelium lining small vessels was highly activated in areas of inflammation, as the endothelial cells became cuboidal, and exhibited increased expression of major histocompatibility complex class II (Ia), intercellular adhesion molecule 1, and von Willebrand Factor. Furthermore, induction of vascular addressins simultaneously with accumulation of mononuclear cells around islets and vessels indicated that the endothelial cells take on the phenotype of differentiated endothelium specialized for leukocyte extravasation. In conclusion, pancreatic inflammation and vascular changes are prominent in IL-10 transgenic mice. We hypothesize that IL-10, in addition to its immuno-inhibitory properties, is a potent recruitment signal for leukocyte migration in vivo. These effects are relevant for in vivo therapeutic applications of IL-10.

Animals↗

PubMed1993

Induction of type I diabetes by interferon-alpha in transgenic mice.

Type I diabetes is an autoimmune disease involving an interaction between an epigenetic event (possibly a viral infection), the pancreatic beta cells, and the immune system in a genetically susceptible host. The possibility that the type I interferons could mediate this interaction was tested with transgenic mice in which the insulin-producing beta cells expressed an interferon-alpha. These mice developed a hypoinsulinemic diabetes associated with a mixed inflammation centered on the islets. The inflammation and the diabetes were prevented with a neutralizing antibody to the interferon-alpha. Thus, the expression of interferon-alpha by the beta cells could be causal in the development of type I diabetes, which suggests a therapeutic approach to this disease.

Animals↗

PubMed1993

Generation and characterization of ex vivo propagated autologous CD8+ cells used for adoptive immunotherapy of patients infected with human immunodeficiency virus.

Cytolytic T lymphocytes play an important role in host defense against viral infections, including human immunodeficiency virus (HIV). In a phase I clinical trial (protocol 080 of the AIDS Clinical Trials Group), generation of CD8+ effector cells from peripheral blood of patients with acquired immunodeficiency syndrome (AIDS)-related complex (ARC) or AIDS and safety of autologous adoptive transfer of these cells were evaluated. For therapeutic infusions, CD8+ T cells were purified by positive selection on anti-CD8 monoclonal antibody-coated flasks from leukapheresed peripheral blood of seven patients. These CD8+ T cells were cultured in the presence of interleukin-2 and phytohemagglutinin for up to 3 weeks to obtain cells sufficient for therapeutic infusions (10(8) to 10(10)). All 31 cell cultures established from the seven patients and used for therapy were highly enriched in CD8+ (mean, 97%), CD8+HLA-DR+ (50%), cytotoxic CD8+CD11b- (82%), and memory CD29+ (78%) T lymphocytes. In vitro expanded CD8+ cells had excellent cytotoxic function at the time they were used for therapy, including HIV-specific activity against autologous targets infected with vaccinia vectors expressing HIV-IIIb antigens, gag, pol, and env. Anti-HIV activity of cultured CD8+ cells was significantly higher than that of autologous fresh peripheral blood lymphocytes. Our results show that CD8+ T lymphocytes obtained from peripheral blood of symptomatic HIV-infected patients can be purified, cultured to obtain large numbers of cells with enhanced anti-HIV activity, and safely infused into patients with AIDS as a form of immunotherapy.

AIDS-Related Complex↗

PubMed1993

46,XY/47,XYY male with the fragile X syndrome: cytogenetic and molecular studies.

We report the first case of a 46,XY/47,XYY mosaic male with fragile X [Fra(X)] expression in both cell lines. Cytogenetic analysis, DNA linkage analysis, and direct detection of the pre- and full mutation for the affected individual and his at-risk female relatives were performed. Southern analysis of PstI-digested DNA with probe pX6 clearly distinguished the normal genotype, the premutation, and the full mutation in various individuals in the patient's family. Fra(X) carriers who had normal cytogenetic results were clearly identified by direct mutation analysis.

Cytogenetics↗

PubMed1993

Quantitative interpretation of magnetization transfer.

Magnetization transfer contrast (MTC) experiments using off-resonance irradiation have been performed with an agar gel model by systematically varying offset frequency, amplitude of the RF irradiation and gel concentration. The experimental results are shown to be quantitatively modelled by a two-pool system consisting of a liquid pool with a Lorentzian line shape and a small semisolid pool with a Gaussian lineshape. The fitted model yields physically realistic fundamental parameters with a T2 of the semisolid pool of 13 microseconds. Further analysis shows that the off-resonance irradiation MTC experiment had significant limitations in its ability to saturate the semisolid pool without directly affecting the liquid component.

Agar↗

PubMed1993

Nickel induces increased oxidants in intact cultured mammalian cells as detected by dichlorofluorescein fluorescence.

Exposure of intact cultured Chinese hamster ovary (CHO) cells to water-soluble nickel (Ni) salts and to relatively water-insoluble crystalline nickel subsulfide (Ni3S2) resulted in an increased formation of the fluorescent oxidized compound, dichlorofluorescein (DCF) from the parent nonfluorescent compound, 2,7-dichlorofluorescin diacetate. This fluorescent product was also formed in vitro following oxidation with relatively strong oxidants such as hydrogen peroxide in the presence of peroxidase, suggesting that Ni increased the concentration of hydrogen peroxide in intact cells. However, formation of other strong oxidants such as hydroperoxides is possible since they have also been shown to cause the oxidation of the nonfluorescent dichlorofluorescin to the fluorescent product DCF in vitro. Localization of the oxidized fluorescent DCF in intact cells was also examined by fluorescence microscopy. Both Ni3S2 and NiCl2 appeared to increase the degree of fluorescence in intact CHO cells around the nuclear membranes. This increase in fluorescence was greater in the presence of relatively water-insoluble Ni3S2 than water-soluble NiCl2. These results add to the emerging concept that Ni-induced genotoxicity may be mediated by oxygen radical intermediates.

Amitrole↗

PubMed1993

Expression of alpha 1, alpha 5, and gamma 2 GABAA receptor subunit mRNAs measured in situ in rat hippocampus and cortex following chronic flurazepam administration.

Prolonged benzodiazepine treatment of rats results in anticonvulsant tolerance in vivo. Studies of in vitro hippocampal slices following 1 wk flurazepam administration show reduced GABA-mediated inhibition in the CA1 region, and a decrease in GABAA agonist and benzodiazepine potency to inhibit CA1 pyramidal cell-evoked responses. To investigate the molecular basis of benzodiazepine tolerance in the hippocampus, in situ hybridization techniques were used to evaluate the expression of the mRNAs for the alpha 1, alpha 5, and gamma 2 subunits of the GABAA receptor in the hippocampal formation and frontal cortex of chronic flurazepam-treated rats. A discretely localized decrease in alpha 1, but not alpha 5 or gamma 2 mRNA expression was found in the CA1 region (35-40%) and in layers II-III and IV of cortex (50-60%) 2 d after cessation of flurazepam treatment. The decrease in the expression of alpha 1 subunit mRNA in cortex is similar to that reported following other chronic benzodiazepine treatment regimens. This is the first report of a reduction in alpha 1 subunit mRNA expression in the hippocampal formation.

Animals↗

PubMed1993

Alterations of muscle activities and jaw movements after blocking individual jaw-closing muscles in the miniature pig.

Although the inactivation or removal of motoneurones and muscles are known to affect development and growth of the craniofacial skeleton and masticatory muscles, the effect of these on functional activity patterns is not clear. The goal of this study was to evaluate the immediate responses of masticatory muscle activities to temporary nerve blocks of individual jaw-closing muscles. Nineteen experiments were made with four miniature pigs (Sus scrofa). Electromyograms of the masticatory muscles and jaw movements were recorded during natural chewing. Then, the function of individual jaw-closing muscles was removed unilaterally by local anaesthesia, and the recording repeated. The results showed a general increase in the activities of the other jaw-closing muscles, particularly those that were synergistic with the blocked muscle in producing lateral movements. Furthermore, the lateral pterygoid showed stronger activity, and accordingly the lateral movement was increased. Digastric muscle activity and the magnitude of jaw opening also tended to increase. Thus, the response to loss of a muscle is a strong, immediate compensation by synergists.

Animals↗

PubMed1993

Effects of serotonin on retinotectal-, corticotectal-, and glutamate-induced activity in the superior colliculus of the hamster.

1. Single-unit recording and iontophoretic techniques were used to test the effects of serotonin (5-HT) on the responses of neurons in the superficial layers (the stratum griseum superficiale and stratum opticum) of the hamster's superior colliculus (SC). 2. Iontophoresis of 5-HT produced a visual response suppression of 40% or greater in 78.1% (n = 50) of 64 neurons tested. 5-HT did not augment the visual responses of any of the cells tested. The average response suppression was 75.3 +/- 21.2% (mean +/- S.D.). 3. Iontophoresis of 5-HT had significantly different effects on activation of SC cells by optic chiasm (OX) and visual cortical (CTX) stimulation. Application of 5-HT suppressed the OX-evoked responses of 96.9% (n = 31) of the 32 SC cells tested by at least 40%, and the average response suppression for all 32 neurons tested was 87.1 +/- 22.5%. Application of 5-HT suppressed the responses of only 35.7% (n = 10) of the 28 cells tested with CTX stimulation by at least 40%. The average response suppression for all 28 cells was 35.3 +/- 38.8%. 4. The effects of 5-HT on the glutamate-evoked responses of SC cells that were synaptically "isolated" by concurrent application of Mg2+ were also evaluated. Application of 5-HT produced a response suppression > or = 40% in 29.7% (n = 19) of the 64 neurons tested under these conditions. The average response suppression for all of the cells tested was 28.4 +/- 35.7%. This effect of 5-HT was significantly weaker than that on visually evoked responses of these neurons. 5. The present results demonstrate that 5-HT markedly depresses the visual responses of most superficial layer SC neurons. They suggest further that much of this effect is mediated by presynaptic inhibition of retinotectal transmission.

Animals↗

PubMed1993

Compartmentalization in the pig latissimus dorsi muscle.

Portions of the latissimus dorsi (LD) muscle are frequently employed as free muscle or myocutaneous grafts. The functional consequences for both the graft and the remaining donor tissue must depend in part on the neural organization of the muscle. Previous anatomical and clinical reports have suggested that the LD is organized into independently innervated segments, but experimental documentation has been lacking. This study investigated the neural organization of the LD in pigs using (1) synchronous electromyography (EMG) of several sites within the LD and motion analysis of the shoulder and forelimb, and (2) dissection and stimulation of the primary branches of the thoracodorsal nerve, followed by histochemical analysis, to delineate the areas innervated by each. The findings indicated that while there is minor overlap between adjacent segments, the LD can be considered as consisting of three semi-independent compartments. Further, the teres major is linked to the LD functionally as well as anatomically, so that the two muscles can be considered as a four-part complex.

Animals↗

PubMed1993

Effects of oral sensory afferents on mastication in the miniature pig.

The performance of mastication is presumed to be influenced by afferent stimulation, but little information is available from awake, intact animals. Thirteen experiments were carried out with four miniature pigs. Electromyographic signals from the jaw muscles were recorded simultaneously with jaw movements during natural chewing of foods of differing hardnesses. Harder foods were found to be associated with higher activity levels of jaw-closing muscles and greater lateral deviation, but reduced jaw opening. The sensory supply from one side of the oral cavity was then removed by injected local anesthetic, and the recordings repeated. In addition to decreased activity levels, the jaw-closing muscles showed reduced ability to adjust to different foods. The frequency of mastication fell slightly, and the animals preferred to chew on the uninjected side. Lateral deviation was reduced, but at the same time the jaw-opening muscles usually became more active and accordingly the jaw opened more widely. These findings provide new information on the role of oral sensory afferents in regulating natural chewing patterns. The decreased activities of the jaw-closing muscles are consistent with, although they do not demonstrate, the existence of a positive feedback from periodontal afferents.

Afferent Pathways↗

PubMed1993

[Amino acid analysis of retinal S-antigen and interphotoreceptor retinoid-binding protein].

Retinal S-antigen and interphotoreceptor retinoid-binding protein (IRBP) were purified by DEAE-Sephacel ionexchange chromatography and Con A Sepharose affinity chromatography. Amino acid analysis of the S-antigen and IRBP was carried out and compared with that presented by others. The possible reason for difference with regard to some amino acids and related problems were analyzed and discussed.

Amino Acids↗

PubMed1993

[Evidences for the appearance of peripheral activator during the advance of PSM].

Investigation on mechanism underlying the formation of the propagated sensation along meridians (PSM) is one of the important problems in meridian research. In order to interpret the problem more satisfactorily, we had advanced a hypothesis in 1987, that is, 'integration of periphery' and CNS under the domination of substantial process proceeding along the meridians". According to this hypothesis, "periphery" and "central mechanism" are operated as a whole. However, it also emphasized that the peripheral substantial process is the determinant factor in the formation of PSM. And then, is there really a peripheral substantial process, or, in other word, a peripheral activator during the advance of PSM. The afferent discharges were directly led from the superficial branch of radial nerve. Nineteen volunteers with marked PSM were under observation. The preliminary results demonstrated that as PSM, evoked by stimulating Jianyu (LI15) or Ying Xiang Acupoint (LI20), travelled along the course of Large Intestine Meridian to the hand or index finger, the corresponding afferent impulses could be recorded from that nerve branch in a part of experiments. Through a series of control observations, it has been proved that the impulses recorded was not resulted from other responses, but really the afferent impulse discharged by the neuroreceptor apparatus distributing along the meridian, which was activated by certain stimulation. The facts demonstrated that "the peripheral activator" really appeared during the advance of PSM. It is of significance for the investigation on the mechanism underlying the formation of PSM.

Acupuncture Points↗

PubMed1993

[Influence of mechanical pressure applied on the stomach meridian upon the effectiveness of acupuncture of zusanli].

Traditional Chinese Medicine holds that meridians is the regulative system of the functional activity of the human body. According to the theory of meridians there is a relatively specific connection between the acupoint and viscus. Not a few researchers have paid much attention to this problem. Our previous report showed the mechanical pressure could block the borborygmi caused by puncturing Zusanli (ST 36) in the subjects with marked propagated sensation along meridians (PSM). This paper deals with experiments to compare the influence of pressing the meridian course and non-meridian point on electrogastrogram (EGG) during puncturing Zusanli in 33 subjects without PSM. The acupoint Liangqiu (ST 34) was selected as a compressed point and the points on its either side as controls. EGG was recorded with surface non-polarizable electrode from two abdominal points corresponding to the areas of corpus ventriculi and antrum pyloricum. The effect of acupuncture on EGG appeared in two kind of responses which depended on the amplitude of EGG before acupuncture. The amplitude of EGG increased if it was low before acupuncture. On the contrary, it decreased. The response was bi-directional. It is particular to be noticed that the acupuncture effect was markedly influenced by mechanical pressure. When the pressure was applied on acupoint Liangqiu the acupuncture effect markedly decreased, even disappeared. Whereas mechanical pressure was applied on the both side of Liangqiu, an influence on acupuncture effect of EGG could not be found.(ABSTRACT TRUNCATED AT 250 WORDS)

Acupuncture Points↗

PubMed1993

[Studies on the low skin impedance points and the feature of its distribution along the channels by microcomputer. II. Distribution of LSIPS along the channels].

The distribution of low skin impedance poionts (LSIPS) was observed on 60 healthy volunteers with a computer system designed to measure the skin impedance. The results demonstrated that LSIPs basically distributed along the channels. The method used was reliable and results obtained was repeatable. Some problems, which puzzled the researchers for so many years, now have been clarified and the method for measuring the skin impedance has been developed to a new level. Under the specified condition, the skin impedance can be used as an indicator to plot out the courses of channels in the research.

Adult↗

PubMed1993

[Distribution of low skin impedance points along meridians over the medial side of forearm].

The distribution of low skin impedance points (LSIP) over the medial side of forearm was plotted with a computer system designed for the measurement of skin impedance. Twelve volunteers were under observation. The exploring electrode moved forward in a even velocity from the radial axis of forearm to its ulnar axis and crossed the Lung meridian, Pericardium meridian and Heart meridian in succession. Thus, the measurement covered the whole area of the medial side of forearm. The results showed that the most of 391 LSIPs located right on or within 5 mm bilaterally to the travelling courses of Three Ying Meridians of Hand. It could be found in the area between every two meridians only in a few cases. Just so, the courses of Three Ying Meridians of Hand were clearly displayed. Under the condition of this experiment, LSIP appeared randomly, but viewing the situation as a whole, the distribution of LSIPs was still following the meridian courses. The results further demonstrated that the distribution of LSIPs along meridian courses not caused by the errors in measurement, but really a biological phenomenon, which was objectively existed.

Adult↗