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Biomedical subjects

H Huang

Publications and source records attributed to H Huang.

At least 559 records · Page 31Linked to original sources
PubMed1992

Direct, simplified, and sensitive assay of angiotensin II in plasma extracts performed with a high-affinity monoclonal antibody.

A very simple, fast, and sensitive RIA of angiotensin (Ang) II has been developed, based on a monoclonal antibody with high affinity and specificity, making possible the direct measurement of circulating Ang II in human plasma after solid-phase extraction. The purified monoclonal antibody 4D8 has an association constant of 1.3 x 10(11) L/mol with Ang II and a cross-reactivity of < 1% for Ang I. The assay can detect as little as 0.8 fmol of Ang II in 2 mL of plasma and is not influenced by the presence of Ang I. Analytical recoveries between 112% and 116% were obtained for Ang II added to human plasma at physiological concentrations. Comparison of the RIA with a reversed-phase, high-performance liquid chromatographic method followed by RIA to measure Ang II in human plasma samples from normal and hypertensive subjects--and from normotensive subjects before and after an acute inhibition of angiotensin-converting enzyme with captopril (50 mg)--showed a high degree of correlation (r2 = 0.93) between the two methods.

Angiotensin II↗
PubMed1992

A study on optimum load for physical work.

Five healthy men were chosen as experimental subjects and were divided into groups at random. The subjects walked with a load in a shoulder-waist-back manner on the treadmill at the speed of 5, 7 and 9 km h-1. The parameters measured were as follows: oxygen expenditure, energy consumption, heart rate and self appraisal. Based on the experimental results and analysis of multiple regression, the authors suggested that physical loading should not exceed 25 kg (i.e. roughly equal to 39% of average body weight of male Chinese), when the walking speed was at 5 km h-1. The suitable loading at physical work would be 20 kg (i.e. equal to 31% of the average body weight of male Chinese).

Adult↗
PubMed1992

Acupuncture at otoacupoint heart for treatment of vascular hypertension.

The immediate, short-term and long-term depressor effects, the immediate effects on cardiac functions in grade II and grade III vascular hypertension, and the effects on angiotensin II in grade III vascular hypertension by acupuncture at otoacupoint Heart were studied in 30 cases of vascular hypertensive patients. The immediate depressor effect of acupuncture at otoacupoint Stomach was also recorded for comparison. It was found that acupuncture at otoacupoint Heart produced marked immediate depressor effect, and the short-term effective rate was 100%, the long-term effective rate was 63.3%, as well as evident immediate effects on cardiac functional activities in grade II and grade III hypertension and marked effects on angiotensin II in grade III hypertension. Acupuncture at otoacupoint Stomach produced no depressor effect on vascular hypertension.

Acupuncture Points↗
PubMed1992

[Screening and distinguishing heavy chain variable region genes of McAb against encephalitis type B virus].

In order to prepare human-mouse chimeric antibody against encephalitis type B virus, hybridoma 51-8 cells secreting monoclonal antibody against the virus were used as material for isolating heavy-chain variable region gene of the McAb. High molecular weight DNA of the hybridoma cell was partially digested by BamHI, and then constructed a gene library containing 2 x 10(7) pfu with lambda EMBL-3 as vector. With cDNA of heavy-chain variable region of the monoclonal antibody as probe, nine positive plaques were screened from 360,000 plaques, which have been proven that they contained a fragment of heavy-chain variable region genes by dot hybridization and Southern hybridization. Four recombinants among the nine positive plaques were further distinguished with J11 probe containing J3, J4 and heavy-chain enhancer. After cutting by EcoR1, there was a 3.8 kb fragment in three recombinants as similar to that in liver cell and Sp2/0 cell, but not in the fourth recombinant (lambda 8a4) which contained a 4.5 kb fragment that did not present in liver cell and Sp2/0 cell. The results showed that the inserts in former 3 recombinants were non-rearranged fragment of heavy-chain variable region genes, but the insert in lambda 8a4 contained a rearranged functional variable region gene. The 4.5 kb fragment could not be hybridized with a probe containing J1 and J2, but contained VH, J3 or/and J4 and enhancer, that further proved it was a functional variable region gene. Therefore, the 4.5 kb fragment was isolated and subcloned in pUC 19, and its physical map was made.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

An immune model of beryllium-induced pulmonary granulomata in mice. Histopathology, immune reactivity, and flow-cytometric analysis of bronchoalveolar lavage-derived cells.

BACKGROUND: Beryllium compounds can cause acute and chronic lung injury in humans. Although models of chronic granulomatous lung disease have been established in various animal species, a murine model of beryllium-induced chronic lung disease has not been established. EXPERIMENTAL DESIGN: Beryllium was introduced intratracheally either as a soluble salt (BeSO4) or in particulate form (BeO). Various preimmunization protocols were used to enhance immune-mediated pulmonary changes. Cells obtained by bronchoalveolar lavage (BAL) were analyzed using flow cytometry, and the observations correlated with in vitro immune responses and with lung histopathology. RESULTS: Histologic changes were consistently found in mice preimmunized with BeSO4.4H2O plus syngeneic serum. Addition of complete or incomplete Freund's adjuvant to the preimmunization protocol was not necessary to induce granulomatous changes. BAL showed a significant increase in lymphocytes at 2, 4, and 8 weeks after intratracheal BeSO4. Approximately one-third of BAL lymphocytes expressed the gamma/delta T lymphocyte receptor at 2 weeks; at 4 weeks the lymphocytes were predominantly Thy1+, L3T4+ (CD4+) and expressed only the alpha/beta T lymphocyte receptor. Only BAL lymphocytes from mice preimmunized with BeSO4/serum and challenged with BeSO4/serum showed significant in vitro proliferation in response to BeSO4. Macrophage activation antigens (Mac-2, Mac-3) were expressed only during the acute inflammatory phase (2 weeks) whereas increased expression of a monocyte/macrophage antigen (Mac-1) remained elevated beyond the inflammatory period in some instances. Attempts to induce similar lesions in BALB/c and C57BL6/J mice were unsuccessful. Genetic differences at the H-2 major histocompatibility complex gene complex may account for the differential responses to BeSO4 among various mouse strains. A single exposure to BeO also induced histopathologic changes in the lung which correlated with BAL cellularity, but these changes were only observed 8 months after exposure and did not proceed to frank granulomas. CONCLUSIONS: A murine model of granulomatous lung disease may prove useful in understanding the genetic and immunologic factors that determine the response to beryllium. The animal model may also have implications for pulmonary sarcoidosis, a disease of unknown cause(s), whose disease manifestations and BAL profiles are difficult to distinguish clinically and pathologically from chronic beryllium disease.

Animals↗
PubMed1991

Isolation and sequence analysis of TGA1 cDNAs encoding a tomato G protein alpha subunit.

We have isolated cDNAs for a gene coding for a G protein alpha subunit from tomato (Lycopersicon esculentum, cv. VF36). This gene, named TGA1, was isolated using a cDNA of the Arabidopsis thaliana G protein alpha subunit-encoding gene, GPA1, as a DNA probe. The sequences of four cDNA clones indicate that the deduced amino acid (aa) sequence of the gene product (TG alpha 1) has 384 aa (44906 Da). The predicted TG alpha 1 protein exhibits similarity to all known G protein alpha subunits. The aa are 84.6% identical and 93% similar (identical and conservative changes) to A. thaliana GP alpha 1, and 34% identical and 59% similar to mammalian transducins. Furthermore, it has all of the consensus regions for a GTP-binding protein. Finally, hybridizations of tomato genomic DNA indicate that TGA1 is a single-copy gene.

Amino Acid Sequence↗
PubMed1991

Overlapping retrovirus U5 sequence elements are required for efficient integration and initiation of reverse transcription.

A secondary structure in the 5' noncoding region of avian retrovirus RNA, called the U5-leader stem, was shown previously to have a role in initiation of reverse transcription (D. Cobrinik, L. Soskey, and J. Leis, J. Virol. 62:3622-3630, 1988). We now show that an additional RNA secondary structure near the U5 terminus, called the U5-IR stem, is also important for reverse transcription. Mutations that disrupt the U5-IR stem cause a replication defect associated with both a decrease in synthesis of viral DNA in infected cells and a decrease in initiation of reverse transcription in melittin-permeabilized virions. Structure-compensating base substitutions in the U5-IR restore reverse transcription efficiency. In viral DNA, U5-IR sequences are included in the U5 terminal region that functions as a viral integration donor site. When base substitutions are introduced into these sequences, a reduced efficiency of integration in vitro and in vivo is observed. These observations indicate that U5-IR sequences have a structural role in reverse transcription of viral RNA and a sequence-specific role in the integration of viral DNA.

Avian Sarcoma Viruses↗
PubMed1991

Characterization of monoclonal antibodies against the human immunodeficiency virus matrix protein, p17gag: identification of epitopes exposed at the surfaces of infected cells.

Eight monoclonal antibodies reactive with the matrix protein of human immunodeficiency virus type 1 (HIV-1), p17gag, were isolated from rats which had been immunized with solubilized HIV-1 lysate. The epitope specificities of these antibodies were determined with a series of synthetic peptides representing overlapping regions of p17. Six of the antibodies were mapped to three distinct regions of p17, while two antibodies (G11g1 and G11h3) reacted only with intact recombinant p17, suggesting that they were directed against conformational or discontinuous epitopes. All the antibodies bound to HIV-infected cells which had been permeabilized with acetone, but only G11g1 and G11h3 reacted with live HIV-infected cells. Specificity studies with diverse virus strains demonstrated that these two antibodies recognized distinct epitopes, one which was group specific for HIV-1, and one which was shared with HIV type 2 and simian immunodeficiency virus. Binding competition studies indicated that these epitopes were proximal in native p17. Despite their reactivity with intact cells, these two antibodies did not possess appreciable virus-neutralizing activity. These results indicate that a form of p17 is expressed on the surfaces of live HIV-infected cells which is accessible to some, but not all, antibodies against p17. These cell surface molecules may play a role in the generation of antibodies against p17gag that are characteristic of early stages of HIV infection, and they may act as natural targets for the immune system and as potential targets for immunotherapy of HIV-infected cells.

Amino Acid Sequence↗
PubMed1991

Chronic nonocclusive coronary artery constriction in rats. Beta-adrenoceptor signal transduction and ventricular failure.

To determine the effects of chronic coronary artery constriction on the relationship between cardiac function and regulation of beta-adrenoceptor signal transduction, the left main coronary artery was narrowed in rats and the animals were killed 5 mo later. An average reduction in coronary luminal diameter of 44% was obtained and this change resulted in an increase in left ventricular end-diastolic pressure and a decrease in positive and negative dP/dt. Significant increases in left and right ventricular weights indicative of global cardiac hypertrophy were observed. Radioligand binding studies of beta-adrenoreceptors, agonist-stimulated adenylate cyclase activity, and ADP ribosylation of 45-kD substrate by cholera toxin were all depressed in the failing left ventricle. In contrast, in the hypertrophic non-failing right ventricle, beta-adrenoreceptor density was preserved and receptor antagonist affinity was increased. In spite of these findings at the receptor level, agonist stimulated cyclic AMP generation was reduced in the right ventricular myocardium. The quantity of the 45-kD substrate was also decreased. In conclusion, longterm nonocclusive coronary artery stenosis of moderate degree has profound detrimental effects on the contractile performance of the heart in association with marked attenuation of adrenergic support mechanisms.

Adenylyl Cyclases↗
PubMed1991

A field study of cold effects among cold store workers in China.

A field study was carried out among cold store workers in China. A self administrative questionnaire and health check-up were taken among 463 male workers from two different types of cold stores, all during their whole daily work. 296 men from Lower Temperature Stores (LTS), where the air temperature was between -10 to -25 degrees C, and 167 men from Ice Stores (IS), where the air temperature was between -5 and +5 degrees C participated. Another group of 152 men working in normal stores and exposed to an air temperature between 20 and 30 degrees C served as a control group. The study did not indicate any special disease attributable to the cold environment. The number of complaints of lower back pain and knee pain in the cold exposed group were significantly higher than that of the control group (in LTS: 42.3%, 46.6%; IS: 52.7%, 50.8%; control group: 9.2%, 14.5%; low back and knee pain, respectively). After 5 years of cold exposure work, the lower back and knee symptoms were very frequent. The point press pain on the knees of the cooler group (LTS) was higher than in the moderate cold group (IS). We suppose that the cold factor contributed to lower back and knee pain. 12.2% of 463 cold exposed workers had frostbite on the body extremities viz: hand, foot and ear. Self estimation of health indicated more problems among cold exposed workers (28.0%) than control group (2.7%).

Adult↗
PubMed1991

[Determination of peanut agglutinin receptor in the diagnosis of nasal neoplasms].

Formalin-fixed paraffin-embedded biopsy specimens of normal nasal mucosae, nasal polyps, nasal inverted papillomas and nasal papillary adenocarcinomas were tested by biotinylated peanut agglutinin (PNA) for the demonstration of PNA receptor. The normal nasal mucosae showed a total absence of epithelial staining. In nasal polyps, PNA bound to supranuclear portion of cells (68 cases, 85%) but not to apical cytoplasm. In case of inverted papilloma, PNA showed a positive reactivity in the plasmatic membranes of 47 cases (78.33%) and in the perinuclear cytoplasm of 52 cases (86.67%), with an increase in PNA positively related to the degree of dysplasia. In papillomatous adenocarcinoma, PNA binding was present in the apical cytoplasm of 37 cases (92.5%) with a linear pattern and in the supranuclear portion of 3 cases (7.5%). It may suggest that the quantity and distribution of PNA receptor in the cells of nasal mucosae are related to their differentiation and transformation.

Adenocarcinoma, Papillary↗
PubMed1991

Unstable tibio-fibular fractures treated with an external fixator--a clinical report of 1033 cases.

From 1977 to 1987, 1033 cases of unstable tibio-fibular fractures were treated with an external fixator designed by the authors. Among them, 232 involved open fractures. All of the patients were followed up for 4 to 90 months (average 20 months). The duration of bed confinement averaged 8.3 days, and the mean time necessary for clinical bone union was 54 days. Anatomical or nearly anatomical bone apposition was effected in 878 cases (85.0%), functional apposition in 141 cases (13.6%) and malunion in 14 cases (1.4%). The overall functional results were as follows: excellent in 769 cases (74.4%), good in 218 cases (21.1%), fair in 32 cases (3.1%), and poor in 14 cases (1.4%). The design of the device and its indications are also discussed.

Adolescent↗
PubMed1991

Expression of firefly luciferase gene in Xenopus laevis oocyte.

Fusion plasmid pSV-Luc20 and pSV-Luc19 were constructed by using the larger BamHI restricted fragments of plasmid pDO432 containing the firefly luciferase (luc) gene and HindIII-BamHI restricted fragment of plasmid pSVK100 containing the SV-40 promoter as insert and vector, respectively. The fusion plasmid had different ligation orientations between the encoding sequence of luc gene and the SV-40 promoter, i.e., they were sense and antisense plasmid. When they were introduced into Xenopus oocyte by micro-injection, only pSV-Luc20 could be transcribed and translated into the enzymatic protein of luciferase with high biological activity. Therefore, firefly luciferase gene and Xenopus oocyte can be used as an excellent system for monitoring the activity of various promoters.

Animals↗