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Biomedical subjects

J Huang

Publications and source records attributed to J Huang.

At least 595 records · Page 33Linked to original sources
PubMed1996

Proteasome complex as a potential cellular target of hepatitis B virus X protein.

Although the biological importance of hepatitis B virus X protein (HBX) in the life cycle of hepatitis B virus has been well established, the cellular and molecular basis of its function remains largely undefined. Despite the association of multiple activities with HBX, none of them appear to provide a unifying hypothesis regarding the true biological function of HBX. Identification and characterization of cellular targets of HBX remain an essential goal in the elucidation of the molecular mechanisms of HBX. Using the Saccharomyces cerevisiae two-hybrid system, we have identified and characterized a novel subunit of the proteasome complex (XAPC7) that interacts specifically with HBX. We also showed that HBX binds specifically to XAPC7 in vitro. Mutagenesis studies have defined the domains of interaction to be critical for the function of HBX. Furthermore, overexpression of XAPC7 appeared to activate transcription by itself and antisense expression of XAPC7 was able to block transactivation by HBX. Therefore, the proteasome complex is possibly a functional target of HBX in cells.

Amino Acid Sequence↗
PubMed1996

Differences between MyoD DNA binding and activation site requirements revealed by functional random sequence selection.

A method has been developed for selecting functional enhancer/promoter sites from random DNA sequences in higher eukaryotic cells. Of sequences that were thus selected for transcriptional activation by the muscle-specific basic helix-loop-helix protein MyoD, only a subset are similar to the preferred in vitro binding consensus, and in the same promoter context an optimal in vitro binding site was inactive. Other sequences with full transcriptional activity instead exhibit sequence preferences that, remarkably, are generally either identical or very similar to those found in naturally occurring muscle-specific promoters. This first systematic examination of the relation between DNA binding and transcriptional activation by basic helix-loop-helix proteins indicates that binding per se is necessary but not sufficient for transcriptional activation by MyoD and implies a requirement for other DNA sequence-dependent interactions or conformations at its binding site.

3T3 Cells↗
PubMed1996

Effect of N-methyl-D-aspartate-receptor blockade on hypoxic ventilatory response in unanesthetized piglets.

The central excitatory amino acid (EAA) neurotransmitter glutamate has been shown to mediate the ventilatory response to hypoxia through N-methyl-D-aspartate (NMDA) receptors in anesthetized adult animals. To determine the role of the EAA glutamate in the neonatal ventilatory response to hypoxia, 19 unanesthetized chronically instrumented piglets were studied. Minute ventilation (VE), oxygen consumption (VO2), arterial blood pressure (ABP), heart rate (HR), and blood gases were measured in room air (RA) and after 1, 5, and 10 min of hypoxia (inspired oxygen fraction = 0.10) before and after an infusion of saline or CGS-19755, a competitive NMDA-receptor blocker (10 mg/kg i.v.). Nine control piglets [age 6 +/- 1 (SD) days; weight 2.02 +/- 0.40 kg] and 10 CGS-19755-treated animals (age 6 +/- 1 days; weight 1.90 +/- 0.66 kg) were studied during quiet sleep and in a thermoneutral environment. There was a marked decrease in the VE response to hypoxia after the administration of CGS-19755. The ventilatory response to hypoxia was not modified by saline infusion. Changes in ABP and arterial PO2 during hypoxia were similar between groups, whereas the decrease in arterial PCO2 was significantly less after CGS-19755 administration. The increase in HR with hypoxia was eliminated by the NMDA-receptor blocker administration. VO2 decreased with hypoxia in both groups, but this decrease was more marked after the NMDA-receptor blockade. These results suggest that the central EAA glutamate mediates, at least in part, the hypoxic hyperventilation in unanesthetized newborn piglets.

Animals↗
PubMed1996

Effects of chloral hydrate on the cardiorespiratory response to hypoxia in newborn piglets.

To assess the effects of chloral hydrate (CH) on the cardiorespiratory response to hypoxia in the neonate, 17 newborn piglets were chronically instrumented 48-72 h before study and randomly assigned to a CH group (100 mg/kg, i.p.) or saline group. The animals were intubated and studied under quiet sleep which was determined by behavioral states, and continuous electro-oculographic and electroencephalographic monitoring. Minute ventilation (VE), tidal volume, respiratory rate, arterial blood gases (ABG), oxygen consumption (VO2), arterial blood pressure (ABP) and heart rate (HR) were measured before and after CH or saline administration during room air and after 10 min of hypoxia (fraction of inspired oxygen concentration = 0.10). Cardiorespiratory response to hypoxia was similar before and after saline infusion. Basal VE and the ventilatory response to hypoxia were similar before and after CH administration. In contrast, the basal ABP decreased significantly (p < 0.05) after CH administration, but the ABP response to hypoxia was similar before and after CH. A significant increase in both basal HR and HR with hypoxia was observed after CH administration. In addition, VO2 and ABG were not modified by CH treatment during normoxia and hypoxia. These data demonstrate that a sedative dose of CH does not significantly modify the ventilatory response to hypoxia in newborn piglets. However, CH produced some changes in the cardiovascular system which should be considered when using it in infants with hemodynamic derangements.

Animals↗
PubMed1996

Effects of ATP-magnesium chloride on the cardiopulmonary manifestations of group B streptococcal sepsis in the piglet.

Low dose ATP-MgCl2 is reported to cause selective pulmonary vasodilation during hypoxic and thromboxane mimetic-induced constriction. In addition, it has been shown to increase cardiac output and improve cellular function during circulatory shock. Based on these properties we hypothesized that ATP-MgCl2 might ameliorate the cardiopulmonary manifestations of sepsis secondary to group B streptococci (GBS). We studied 14 anesthetized, mechanically ventilated piglets who received a continuous infusion of GBS (7.5 x 10(7) colony-forming units/kg/min) and were randomly assigned to a treatment group that received a continuous infusion of ATP-MgCl2 at 0.6 mumol/kg/min or a control group that received normal saline as placebo. Comparison of the hemodynamic measurements, pulmonary mechanics, and arterial blood gases over the first 120 min of ATP-MgCl2 infusions with those of the control group revealed the following: GBS infusion caused significant increases in mean pulmonary artery pressure, pulmonary vascular resistance (PVR), mean systemic arterial blood pressure, systemic vascular pressure (SVR), and PVR/SVR ratio with decreases in cardiac output and stroke volume. ATP-MgCl2 caused significant reduction in mean pulmonary artery pressure (p < 0.001), PVR (p < 0.0001), mean systemic arterial blood pressure (p < 0.003), SVR (p < 0.01), and PVR/SVR ratio (p < 0.03) with improvement in cardiac output (p < 0.001) and stroke volume (p < 0.01). The partial pressure of arterial O2 (p < 0.04), and pH (p < 0.001) were higher and the partial pressure of arterial CO2 (p < 0.02) lower in ATP-MgCl2-treated animals. Also dynamic lung compliance was higher (p < 0.001) and pulmonary airway resistance lower (p < 0.001) in treated animals. Median survival in control animals was 153 min, whereas all treated animals survived to 240 min (p < 0.001). These data demonstrate that ATP-MgCl2 ameliorates the deleterious cardiopulmonary manifestations of GBS sepsis and results in improved survival in a young animal model.

Adenosine Triphosphate↗
PubMed1996

Determination of residues important in hormone binding to the extracellular domain of the luteinizing hormone/chorionic gonadotropin receptor by site-directed mutagenesis and modeling.

The LH/CG receptor (LH/CG-R) belongs to the family of glycoprotein hormone G protein-coupled receptors. The extracellular domain of LH/CG-R is associated with high ligand-binding affinity and contains leucine-rich repeats (LRRs). With the goal of identifying essential amino acid residues involved in ligand binding, we replaced several conserved ionizable residues in the rat LH/CG-R with ones of opposite charge. The expression of these mutants was assessed by binding studies and Western blots after COS-7 cells were transiently transfected with wild type and mutant receptor cDNAs. The charge inversion of each of Lys40, Lys104, Asp118, Glu132, and Asp135 with Asp or Lys resulted in no detectable human CG binding in intact or solubilized cells; as control, a Lys40-->Arg replacement yielded a mutant with characteristics of the wild type receptor. Western analysis showed that the Lys40-->Arg mutant expressed at a level comparable to that of wild type receptor and, like wild type, exhibited a predominant immunoreactive mature form of LH/CG-R. Each of the five charge inversion mutants expressed at a lower level than wild type as assessed by immunoreactivity, and the levels of the Lys40-->Asp and Glu132-->Lys mutants were particularly low. The ratio of the mature to immature form of the receptor was high, i.e. like that of wild type, for the Glu132-->Lys and Asp135-->Lys replacements; the three other charge inversion mutants exhibited less mature than immature forms of the receptor. To aid in interpreting these results, we developed a model incorporating residues 27-235 of the extracellular domain of the rat LH/CG-R based on the crystal structure of the porcine ribonuclease inhibitor. Sequence homology and alignment revealed nine LRRs, with flanking cysteine clusters as found in a number of LRR proteins. Our model suggested that the Lys replacements of Glu132 and Asp135, i.e. those mutants that formed mature receptors, would disrupt the regional negative charge of the receptor. We propose that these residues are either directly involved in hormone binding or indirectly by disruption of the charge of an important binding surface.

Amino Acid Sequence↗
PubMed1996

Lung microvascular pressure profile in acute lung injury.

To clarify the role of microvessels in the development of pulmonary hypertension of acute lung injury, we induced lung edema by oleic acid (OA) in ten artificially perfused cat lungs and measured microvascular pressure. Pulmonary artery pressure (Ppa) and pressure of 30-50 microns arteriole (Parteriole) increased from 19.2 +/- 1.4 and 15.7 +/- 1.0 cmH2O before to 30.5 +/- 5.0 cmH2O and 22.7 +/- 2.4 cmH2O after edema, respectively. Pressure of 30-50 microns venule (Pvenule) and venous occlusion pressure (Pvo) did not change significantly after edema. Double occlusion pressure (Pdo) which represents pulmonary microvascular pressure increased from 14.5 +/- 0.6 to 17.7 +/- 2.0 cmH2O. Pressure gradient in the artery, i.e., between Ppa and Parteriole and in the microvessels, i.e., between Parteriole and Pvenule increased when lung became edematous. Pressure gradient in vein, i.e., between Pvenule to left atrium was not affected by edema. Pdo was in the midst of Parteriole and Pvenule in both edematous and non-edematous lung. In acute lung injury, increase of microvascular resistance was followed by an increase of arterial resistance and caused pulmonary hypertension.

Acute Disease↗
PubMed1996

[Preliminary exploration on Zhang Jingyue's thinking of Chinese psychiatry].

As a great medical scholar of the Ming Dynasty with great achievements, Zhang Jingyue made great contributions to the course of TCM, both clinical and theoretical. This paper explores his achievements in psychiatry from the following points: 1. Expounding of etiology and pathogenesis of depressive psychoses; 2. Recognition on etiology and pathogenesis of Mania; 3. Recognition of some special psychoses; 4. Recognition of epilepsy; 5. Recognition of dementia; 6. Recognition of depression; 7. Diagnosis of feign disorders.

China↗
PubMed1996

Elimination of false negative results in the two-hybrid system in the phagocyte NADPH oxidase.

The yeast two-hybrid system is finding increased use in the study of interactions between proteins. In this method, two polypeptides are expressed in yeast as fusion proteins to a transcriptional activator DNA-binding domain (bd) and activating domain (ad), respectively. Interaction between the two polypeptides reconstitutes function of a transactivator which controls expression of reporters. The phagocyte NADPH oxidase is a complex of membrane cytochrome b558 (comprised of subunits p22-phox and gp91-phox) and three cytosol proteins (p47-phox, p67-phox, and p21rac) that translocate to membrane and bind to cytochrome b558. This is the first report to demonstrate that two of cytosolic components of cytochrome b558, p47-phox binding to p67-phox each other. We encountered several methodological problems in the two-hybrid system which are the focus of this report.

False Negative Reactions↗
PubMed1996

Immunohistochemical detection of intracranial vasa vasorum: a human autopsy study.

The existence of intracranial vasa vasorum supplying the larger vessels of the circle of Willis has long been debated. Much of this debate results from contradictory findings of microanatomic studies in a variety of nonprimate species. Recently, however, a growing body of evidence seems to suggest that in certain pathological situations, such as human intracranial atherosclerosis, vasa vasorum are present. In an effort to determine whether intracranial vasa vasorum are present in humans without clinical evidence of intracranial vascular disease, we studied the circle of Willis in five autopsy specimens using immunohistochemistry. Antiserum to the endothelial-specific antigen, Factor VIII, revealed staining of 10- to 20-microns vascular channels in the outer media and adventitial layers. Staining was present in the proximal carotid, middle cerebral (M1), and anterior cerebral (A1) arteries but could not be detected in M2 or A2 segments. Hematoxylin and eosin staining was additionally helpful in identifying the nuclear morphology of the endothelial cells lining these channels, as well as the presence of erythrocytes within them. We conclude that in nonpathological settings, endothelial-lined channels exist in the proximal intracranial vessels of humans. These vessels might represent intracranial vasa vasorum, which in turn might play a role in pathological conditions, such as atheroma formation, intracranial dissection, and vasospasm.

Adolescent↗
PubMed1996

[Comparison between kinetics of positive inotropism of ibopamine and ouabain].

AIM: To compare the kinetics of positive inotropism between ibopamine (Ibo) and ouabain (Oua). METHODS: The isolated right papillary muscle of cat was used to assess the positive inotropic effects by cummulative concentrations of Ibo and Oua. The maximal effects was recognized as the contraction just before the appearance of spontaneous contraction. A Hill equation was developed by using lg [E/(Emax-E)] vs lg C. RESULTS: The S value of Ibo was smaller than that of Oua, causing C95/C5 (ratio of concentrations producing 95%/5% of Emax) of Ibo (264) elevenfold as large as Oua (22.9). Comparing with Oua, concentrations of Ibo initiating effects were lower, the slope was smaller, and higher concentrations were required for producing maximal effect. During drug concentration declining, the effect-concentration curve of Ibo showed a counter-hysteresis loop, more remarkable than Oua. CONCLUSION: The changes in positive inotropism of Ibo against drug concentrations were less than those of Oua.

Animals↗
PubMed1996

[Clinical application of intraoperative sustained limited expansion].

Since May 1993, the technique of intraoperative sustained limited expansion (ISLE) had been applied clinically in 21 cases for the immediate reconstruction of soft tissue defects. Satisfactory results were obtained in 18 cases (85.7%), and failed in 3 cases (14.3%). ISLE had been applied successfully in various regions of the body. It had been shown that the results were dependent on the extent of soft tissue defect, the extent of intraoperative tissue gain, and the time of intraoperative sustained expansion.

Adolescent↗
PubMed1996

Characterization of [3H]ethynylbicycloorthobenzoate ([3H]EBOB) binding and the action of insecticides on the gamma-aminobutyric acid-gated chloride channel in cultured cerebellar granule neurons.

[3H]Ethynylbicycloorthobenzoate ([3H]EBOB) is a recently developed specific radioligand for the noncompetitive blocker site of the gamma-aminobutyric acid (GABA) receptor, which is the target of many polychlorocycloalkane and heterocyclic insecticides. This study characterizes [3H]EBOB binding and the action of insecticides on the GABA-gated chloride channel of cerebellar granule neurons in primary culture. Specific [3H]EBOB binding increases rapidly between days 3 and 7 and then remains constant for days 7 to 12 in culture. A single, high-affinity and saturable binding site is involved with Kd = 0.51 nM and Bmax = 239 fmol/mg protein. GABA and muscimol are 6- to 12-fold more potent as inhibitors of [3H]EBOB binding to membranes from cultured cerebellar granule neurons than from cerebellar tissue, possibly because of localization of specific subunits in the granule cells. GABA-stimulated 36Cl- influx is also inhibited by seven insecticidal compounds (including EBOB, 12-ketoendrin and alpha-endosulfan) as well as picrotoxinin and t-butylbicyclophosphorothionate with IC50 levels ranging from 290 to 15300 nM, which correlate well (r = 0.92) with their inhibitory potencies for [3H]EBOB binding (1 to 773 nM). These findings validate the use of [3H]EBOB binding in cultured cerebellar granule cells for pharmacological studies on insecticides and other toxicants acting at the noncompetitive blocker or coupled site of the GABAA receptor/chloride channel complex.

Animals↗
PubMed1996

Surgical treatment of coronary artery fistulae associated with other cardiovascular anomalies.

OBJECTIVE: To evaluate retrospectively our surgical experience, techniques and long-term results in 11 patients with coronary artery fistulae associated with other cardiovascular anomalies. METHODS: From January 1980 to April 1995, 11 patients with coronary artery fistulae associated with other cardiovascular anomalies were found among 20,000 open-heart procedures and treated surgically. Besides closure of the fistulae, coronary artery bypass grafting was performed in 5 patients with atherosclerotic coronary artery disease, and aneurysm angioplasty was done in 4 patients with coronary artery aneurysm. Ventricular septal defect and patent ductus arteriosus were closed in one patient and mitral valve replacement was performed in another patient. RESULTS: There were no surgical deaths, but one late death due to acute myocardial infarction occurred 6 months after surgery. The mean follow-up time was 75.7 months and all patients' functional status improved by an average 1.4 judged by the New York Heart Association functional classification. CONCLUSIONS: Coronary artery fistula associated with other cardiovascular anomalies will aggravate symptoms and cause deterioration of heart function. Therefore, evaluation and surgical intervention should be done as soon as possible to restore coronary blood flow and correct concomitant cardiovascular anomalies. The surgical results are excellent with a low operative risk and good long-term results.

Adult↗
PubMed1996

[Androgen receptor in hepatocellular carcinoma and the surrounding liver tissues in China].

To investigate the reasons why primary liver cancer (hepatocellular carcinoma, HCC) is prevalent in male, androgen receptors (AR) in cytoplasm and nucleus were quantitatively detected in tumor tissue and tumor-adjacent tissue of 23 patients with HCC and liver tissue of normal livers by means of receptor radio-ligand binding assay. The concentrations of AR in cytoplasm and nucleus were as follows: 0.20-5.30, 1.91-6.50 fmol/mg protein in normal liver tissue; 5.12-27.62, 10.73-47.18 fmol/mg protein in tumor tissue; and 3.18-14.98, 5.15-36.32 fmol/mg protein in tumor-surrounding tissue. The mean concentrations of AR in cytoplasm or nucleus decreased in the order of tumor tissue, tumor-surrounding tissue and normal liver tissue, and the differences among them were statistically significant. The concentration of AR in tumor tissue and tumor-adjacent tissue had no direct or indirect association with sex, age, abuse of alcohol, HBsAg, HBcAb, AFP, pathological type of tumor, differentiation degree of tumor cells and the underlying liver disease. The result suggests that the prevalence of HCC in male over in female in China may be somehow related to the expression of AR in tumor cells.

Adult↗
PubMed1996

[99mTc-pingyangmycin imaging to assess treatment response of patients with lung cancer].

The aim of this study was to investigate the possibility of functional imaging for the assessing of treatment response in patients with lung cancer. Thirty one patients were studied by 99mTc-Pingyangmycin (PYM) imaging. A region-of-interest technique was used in planar scan and the retention index (RI) was obtained to evaluate quantitatively the degree of 99mTc-PYM retention in the lesions. It was found that the RI was significant difference between responder (-5.01 +/- 4.97, -6.78 +/- 3.05) and nonresponder (4.38 +/- 2.13, 15.25 +/- 5.92, P < 0.05, P < 0.001) to chemotherapy or radiotherapy. Significant difference was also seen between patients with stable disease (-6.07 +/- 8.45) and those with disease progression (12.66 +/- 5.23, P < 0.01) after surgical treatment. Repeated examinations showed good correlation between difference of pretreatment and posttreatment RI and reduction of tumor volume (r = 0.8959, P < 0.01). Therefore, RI can be taken as a predictive index in assessing tumor response to treatment and in monitoring lung cancer patients surgically treated.

Adenocarcinoma↗