Search PubMed⌕ Search

Biomedical subjects

H Huang

Publications and source records attributed to H Huang.

At least 307 records · Page 17Linked to original sources
PubMed1999

[A pair-matched comparison and follow-up study of patients with euthytroid Graves ophthalmopathy and patients with hyperthyroid graves ophthalmopathy].

This study was intended to acquire a knowledge about the similarity and difference between euthyriod Graves ophthalmopathy (EGO) and hyperthyroid Graves ophthalmopathy (HGO), and about the outcome of the EGO cases. Twenty-seven EGO patients were pair-matched with 27 HGO patients, and 18 of the EGO patients were followed up for 1-6 years. The results showed that the EGO group had markedly more patients with diplopia, failure to close lids, limitation of eyeball movements, cornea involvement, and more patients with a difference of two eyes' exophthalmos degrees > or = 2 mm, but the HGO group had more patients with optic nerve involvement. No significant difference was found between the two groups' ophthalmopathic indexes by using the t-test. Drug therapy of the EGO group was more efficacious than that of the HGO group. The results of follow-up study showed that 61% of the EGO cases had hyperthyroidism and goiter within 5 months to 3 years, but 39% of the cases had no hyperthyroidism up to 6 years. These data suggest that EGO is associated with thyroid diseases and it can stand "alone" as an auto-immune disease.

Adolescent↗
PubMed1999

[A clinical study of sudden death in patients with type 2 diabetes mellitus].

This study aimed to investigate the clinical characteristics of sudden death (SD) in type 2 diabetes mellitus (DM2). Clinical data from 1988 through 1996 in our hospital showed that 130 hospitalized patients with DM2 died, and 17 of them died of SD (13.08%). These 17 SD patients were pair-matched with 17 DM2 patients who were alive in the same period. The results revealed that the SD group had longer clinical DM duration, more chronic diabetic complications and higher blood pressure. In the direct causes of SD, cardiac SD accounted for 76.47%. The others were non-cardiac factors, including cerebral hemorrhage, hyperkalemia from diabetic nephropathy with renal failure and respiratory tract obstruction from lung infection. The triggering causes included eating, defecting, lung infection, strenuous attempt, hypoglycemia and surgical operation. To reduce the rate of SD in DM2, it is necessary and vital to treat the DM2 itself, and to take positive steps to prevent the onset of SD in high risk patients.

Aged↗
PubMed1999

[p53 gene expression of human hepatoma cell lines and their sensitivities to parvovirus H-1].

DNA structure and expression of p53 gene in human hepatoma cell lines SMMC-7721, YY-8103 and a spontaneously transformed liver cell line L-02 were analysed using the following method: analysis of allelic losses on chromosome 17p, PCR/SSCP, Northern blot and immunoprecipitation. There was no point mutation found in the exons 4-9 of the p53 gene, and a low level of expression of p53 gene was detected in the three cell lines. These observations were in agreement to the reported results of the relevant experiment using the human hepatoma cell line QGY-7703. Sensitivities of these cell lines and other eight human hepatoma cell lines (QGY-7703, PLC/PRF/5, Tong/HCC, Huh-7, FOCUS, Hep3B, SK-Hep-1, HepG2) with known p53 backgrounds to parvovirus H-1 was assayed using MTT method. Abnormality in the structure and/or function was observed in all of the cell lines examined except HepG2. The cell line HepG2 with normal structure and function of the p53 gene was found to be the least sensitive to H-1 in comparison to all the cell lines which have defeated structure and/or function of the p53 gene. The present study serves as a preliminary evidence that enhancement of the sensitivity of human hepatoma cell lines to H-1 is correlated to the abnormality of the structure and/or function of the p53 gene.

Carcinoma, Hepatocellular↗
PubMed1999

[The alternation current conductive property of blood].

The blood electro-frequency properties of normal human body were investigated in the range of 1 Hz-10 MHz. The method of testing and the equipment were examined to meet the need for the measurement of blood property. In the experiment, it was discovered that the electric conductivity of blood increased obviously with the increase of testing frequency in the rage of 100 Hz-10 KHz, but almost no change in phase was noted. This result suggests it is necessary to modify the previous work and build up a reasonable equivalent electric model of blood.

Adult↗
PubMed1999

[Effects of chitin and chitosan on degradation of DL-polylactide in vitro].

The authors assessed the variations of pH-values of the physiological saline used for in vitro degradation tests of DL-Polylactide (DL-PLA)/chitin and DL-PLA/chitosan composites and DL-PLA. The weight-loss rations, the appearance and morphology of the tested specimens, and the molecular weights of DL-PLA in composites and pure DL-PLA were alse investigated. The results showed that both chitin and chitosan had significant inhibitory effects on the degradation of DL-PLA, and the effect of chitosan was stronger than that of chitin. A discussion on the mechanism of such inhibition is presented.

Biocompatible Materials↗
PubMed1999

[Clinical significance and changes of fibrillation potential amplitude following denervation of laryngeal muscles].

OBJECTIVE: To evaluate the value of clinical application of examination of fibrillation potential amplitude of laryngeal electromyogram. METHOD: Fifty-four patients (65 sides) with recurrent laryngeal nerve paralysis were examined and only the maximum fibrillation potential amplitudes were recorded in the posterior cricoarytenoid muscles and thyroarytenoid muscles. RESULT: There was no significant difference between sexes, ages and sides. The fibrillation potential amplitude was maximum at 3 to 4 months after denervation of the posterior cricoarytenoid muscle or at 5 to 6 months after denervation of the thyroarytenoid muscle and still remained at certain level for years in some patients. Significant difference was showed in complete and incomplete nerve injuries groups, but changes of amplitude with time in incomplete nerve injuries group were small. CONCLUSION: The changes of fibrillation potential amplitude might indicate that the changes from muscle denervation was still reversible and might be more accurate than traditional method of examination.

Adult↗
PubMed1999

[Microwave therapy of radiotherapeutical choanal atresia under nasal endoscope].

OBJECTIVE: In order to know efficacy of microwave to treat the secondary choanal atresia under nasal endoscope. METHOD: Three patients suffering from membranous choanal atresia due to radiotherapy of nasopharyngeal carcinoma (NPC) were treated by microwave under nasal endoscope. RESULT: Satisfing recoveries were accomplished in all patients and no relapse was found within the 7-13 months' follow-up. CONCLUSION: This method has many advantages, such as: processing available under local anesthesia without incision, mild damage to normal tissues, clear operation visual field, less hemorrhage and postoperative pain, complete coagulation and gasification of atresic membrane, no need of postoperative dilation and stable therapeutical effect.

Adult↗
PubMed1999

Frequent deletions within FRA7G at 7q31.2 in invasive epithelial ovarian cancer.

We previously showed that FRA7G, an aphidicolin-inducible common fragile site at 7q31.2, colocalized with the common region of loss of heterozygosity (LOH) in a number of different tumors. Based on the sequence analysis of 150 Kb in the FRA7G region, we identified four new polymorphic microsatellite markers. In this article, we have used these four microsatellite markers and eight additional markers from 7q22-32 to analyze the breakage and loss of the region surrounding FRA7G in 49 invasive epithelial ovarian cancers and three borderline ovarian tumors. No allelic loss was detected in the ovarian tumors of borderline malignancy, but 71% (35/49) of the invasive tumors showed LOH at one or more loci in the region analyzed. Of the 12 markers analyzed, most of the markers exhibiting a high frequency of LOH were within FRA7G, and the highest frequency of LOH was seen with the new marker 7G14 (37%, 15/41). Breakpoint analysis in tumors with LOH demonstrated that the frequent loss of DNA sequences seen within the FRA7G region was due to frequent small interstitial deletions and not a result of loss of the whole fragile site region. These findings indicate that FRA7G does play a role in the breakage and loss of 7q sequences in invasive ovarian cancer. In addition, the newly identified markers enable us to further delineate a smallest common region of loss in invasive ovarian tumors to a 150-Kb region flanked by markers D7S486 and 7G14.

Carcinoma↗
PubMed1999

Pathogenesis of porcine Actinobacillus pleuropneumonia, part II: roles of proinflammatory cytokines.

The in vitro production of proinflammatory cytokines after stimulation with Actinobacillus pleuropneumoniae and the relation of these cytokines in vivo with the disease caused by A. pleuropneumoniae were investigated. Within 24 h, in vitro stimulation by A. pleuropneumoniae (serotype 1) preparations, including killed bacteria, bacterial culture supernatant, lipopolysaccharide, and bacterial extracts, porcine pulmonary alveolar macrophages (PAM) produced significant (P < 0.05) amounts of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) as measured by bioassays. The supernatants containing interleukin-8 from PAM after stimulation by bacterial preparations showed significant neutrophil chemotaxis, while bacterial preparations alone did not. After in vivo infection with A. pleuropneumoniae, the mean levels of TNF-alpha and IL-1 in serum, as measured by bioassays, were elevated 37- to 27836-fold for TNF-alpha and 11- to 5941-fold higher for IL-1 within 4 d post-infection, depending on the treatments, and remained elevated up to Day 7. Both cytokines were also detected in porcine lungs by bioassays and immunocytochemistry. The results indicated that both secreted and surface components of A. pleuropneumoniae can stimulate PAM to produce proinflammatory mediators. Neutrophil chemoattractants rather than bacterial components are the major factor causing acute lung inflammation. The elevation of TNF-alpha and IL-1 in pigs occurred coincident with the onset of acute clinical disease.

Actinobacillus Infections↗
PubMed1998

Analysis of DNA adduct, S-[2-(N7-guanyl)ethyl]glutathione, by liquid chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry.

Sensitive and specific isotope dilution liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) methods were developed for the detection and quantitative analysis of S-[2-(N7-guanyl)ethyl]glutathione as a DNA adduct formed upon exposure of animals to carcinogenic 1,2-dihaloethanes. Separation and analysis were performed using microbore HPLC coupled in-line to an electrospray ionization triple quadrupole mass spectrometer. S-[2-(N7-guanyl)[2H4]-ethyl] glutathione was synthesized and used as internal standard. These methods provide structural confirmation of the adduct as well as quantitative analysis with the accuracy and precision necessary to measure biologically relevant levels in small tissue sample sizes (< 1 g). The sample detection limits in in vivo tissue extracts were 100 pg and 5 pg on-column for LC/MS and LC/MS/MS methods, respectively. Selected-ion monitoring mode was used to monitor the product ions of the doubly charged molecular ion. The application of these methods was demonstrated by measuring the DNA adduct levels in rat and fish samples after exposure to 1,2-dihaloethanes. The method has application in studies of DNA adduct formation as a biological marker of exposure to carcinogens and for environmental monitoring of 1,2-dihaloethanes.

Animals↗
PubMed1998

Structure of a covalently trapped catalytic complex of HIV-1 reverse transcriptase: implications for drug resistance.

A combinatorial disulfide cross-linking strategy was used to prepare a stalled complex of human immunodeficiency virus-type 1 (HIV-1) reverse transcriptase with a DNA template:primer and a deoxynucleoside triphosphate (dNTP), and the crystal structure of the complex was determined at a resolution of 3.2 angstroms. The presence of a dideoxynucleotide at the 3'-primer terminus allows capture of a state in which the substrates are poised for attack on the dNTP. Conformational changes that accompany formation of the catalytic complex produce distinct clusters of the residues that are altered in viruses resistant to nucleoside analog drugs. The positioning of these residues in the neighborhood of the dNTP helps to resolve some long-standing puzzles about the molecular basis of resistance. The resistance mutations are likely to influence binding or reactivity of the inhibitors, relative to normal dNTPs, and the clustering of the mutations correlates with the chemical structure of the drug.

Anti-HIV Agents↗
PubMed1998

An HP1-like protein is missing from transcriptionally silent micronuclei of Tetrahymena.

We report the identification and cloning of a 28-kDa polypeptide (p28) in Tetrahymena macronuclei that shares several features with the well studied heterochromatin-associated protein HP1 from Drosophila. Notably, like HP1, p28 contains both a chromodomain and a chromoshadow domain. p28 also shares features with linker histone H1, and like H1, p28 is multiply phosphorylated, at least in part, by a proline-directed, Cdc2-type kinase. As such, p28 is referred to as Hhp1p (for H1/HP1-like protein). Hhp1p is missing from transcriptionally silent micronuclei but is enriched in heterochromatin-like chromatin bodies that presumably comprise repressed chromatin in macronuclei. These findings shed light on the evolutionary conserved nature of heterochromatin in organisms ranging from ciliates to humans and provide further evidence that HP1-like proteins are not exclusively associated with permanently silent chromosomal domains. Our data support a view that members of this family also associate with repressed states of euchromatin.

Amino Acid Sequence↗
PubMed1998

Antimony trichloride induces DNA damage and apoptosis in mammalian cells.

Antimony compounds are widely used in various manufacturing and semiconducting industries. Previously, it has been shown that antimony trichloride (SbCl3) elevates sister chromatid exchange (SCE) rates in V79 cells after a 28-h incubation. However, only limited data on its genotoxic effects are available so far. The present results demonstrate that a 4-h exposure to > 50 microM SbCl3 could induce micronuclei (MN) formation in cultured Chinese hamster ovary (CHO-K1) cells, human bronchial epithelial (BES-6) cells and human fibroblasts (HF). The order of sensitivity to SbCl3 determined by Sulforhodamine B (SRB)-staining survival assay is HF > BES-6 cells > CHO-K1 cells, with LD50 values in these cells being approximately 40, 80 and 180 microM, respectively. Apoptosis and DNA fragmentation was not found in cells immediately following 4-h SbCl3 treatment. However, DNA fragmentation was detected in CHO-K1 cells after 4-h SbCl3 treatment and a 16 h or more post incubation in fresh medium by 1.5% agarose gel electrophoresis. The delayed apoptosis was also observed under microscopic examination in HF, BES-6 and CHO-K1 cells after similar treatment protocol. In addition, an increase in calcium accumulation appeared in CHO-K1 cells and HF immediately after a 4-h SbCl3 treatment, or after a 24-h post incubation in fresh medium. The present results provide important genotoxic and cytotoxic information characterizing the cellular changes induced by short-term SbCl3 exposure in rodent and human cells.

Animals↗
PubMed1998

Factors associated with survival following secondary AIDS: 1988 to 1995.

The second AIDS-defining condition diagnosed chronologically is referred to in this report as the secondary AIDS diagnosis. In this study, we examined survival following a secondary AIDS diagnosis using demographic and clinical factors known within 1 year before secondary AIDS diagnosis. In a prospective cohort of 2412 HIV-seropositive homosexual men observed in the Multicenter AIDS Cohort Study (MACS), 609 presented with a secondary AIDS diagnosis between January 1, 1988 and March 31, 1995. To analyze the data, we used survival analysis methods including the Kaplan-Meier product-limit estimator and extended Cox models that allow for nonproportional hazards. The median survival time after a secondary diagnosis was 10.3 months. Rapidity of progression from an initial AIDS diagnosis to a secondary diagnosis was not associated with survival. Drug treatment did not show a beneficial effect because of confounding by indication (i.e., selection bias) and limited efficacy on advanced disease of treatments available prior to 1995. However, a beneficial effect was captured by the use of calendar periods as a proxy measure for the relative exposure to drug treatments. Later calendar year of secondary diagnosis, secondary Kaposi's sarcoma, and higher CD4+ cell count were found to be significantly (p < .05) associated with longer survival time. However, secondary AIDS diagnosis was a significant factor only in the short term. Using secondary Pneumocystis carinii pneumonia as the reference diagnosis, the relative hazard of death 3 months after the time of secondary Kaposi's sarcoma diagnosis was 0.56 (95% confidence interval [CI] = 0.36-0.89) whereas the relative hazard after concurrently diagnosed multiple secondary illnesses was 2.06 (95% CI = 1.26-3.38). After approximately 1 year from the secondary diagnosis, the type of diagnosis was no longer significantly associated with survival.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Characterization of a mobile Stat6 activation motif in the human IL-4 receptor.

The IL-4R induces proliferation and gene expression through the use of conserved tyrosine residues located in growth and gene regulation domains, respectively. We demonstrate that residues surrounding these conserved tyrosines (juxtatyrosine residues) are essential for the proper activation of the signaling molecules IRS-2 and Stat6, as well as for IL-4-induced gene expression. Further, we found that the IL-4R gene regulation domain (amino acids 557-657) contains a tyrosine-based sequence (EAGYKAF) that can convey Stat6 DNA binding and gene expression activities to a minimally active IL-4R mutant, delta 557. Thus, this tyrosine-based sequence can function as a mobile Stat6 activation cassette. However, mutants bearing this sequence induced CD23 expression much less efficiently than did wild-type IL-4R, requiring 150-fold more IL-4 to reach maximal CD23 expression. Our results indicate the importance of juxtatyrosine residues in IL-4R signaling and argue for an essential role of extended domain structure in the recognition and function of juxtatyrosine sequences.

Adjuvants, Immunologic↗
PubMed1998

Genomic organization and mutation analysis of p73 in oligodendrogliomas with chromosome 1 p-arm deletions.

p73, a protein having substantial structural and functional similarity to p53, has recently been identified and demonstrated to be a potential tumor suppressor. Its location on human chromosome 1p36.33 implicates p73 as a candidate for neuroblastoma. Like neuroblastoma, oligodendrogliomas also show a high frequency of deletions in chromosome 1p36.3. To determine whether p73 is a potential tumor suppressor gene involved in the development of oligodendrogliomas, we performed mutation analysis of p73 in oligodendrogliomas with chromosome 1 p-arm deletions. We first determined the genomic organization and the intron-exon boundary sequences of the p73 gene by long PCR, vectorette PCR, and Southern hybridization. This gene spans about 65 kb with a large first intron. Primer pairs for the amplification of each of the 13 p73 encoding exons were designed in corresponding introns. The amplicons were then analyzed using the denaturing high-performance liquid chromatography system for mutations in the p73 gene. Twenty oligodendroglioma samples with 1p36.3 deletions were screened, but no mutations were detected except for several polymorphisms. It is thus clear that p73 is not a candidate gene for oligodendroglioma despite its location in the frequently deleted 1p36.3 region.

Chromosomes, Human, Pair 1↗
PubMed1998

Transient transfection of primary T helper cells by particle-mediated gene transfer.

The study of the molecular basis of normal CD4+ T cell function, such as the control of commitment to the TH1 or TH2 phenotypes has been difficult due to the resistance of these cells to transfection by conventional methods. We used antibodies specific to T cell surface molecules to immobilize these cells and optimized conditions for transiently transfecting them by means of particle-mediated gene transfer. Using this technique, a construct encompassing - 577 to +1 of the IL-4 promoter allowed transcription of a luciferase reporter gene in recently-differentiated TH2 cells stimulated by anti-CD3, consistent with regulation of endogenous IL-4 gene expression.

Animals↗