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Biomedical subjects

H L Liu

Publications and source records attributed to H L Liu.

At least 73 records · Page 4Linked to original sources
PubMed1996

Effects of egtazic acid and calcimycin on synthesis of DNA and collagen in cultured human lung fibroblasts.

AIM: To study the effects of egtazic acid (EA) and calcimycin (Cal) on the synthesis of DNA and collagen in cultured human lung fibroblasts (HLF). METHODS: The synthesis of DNA and collagen was determined by measuring the incorporation of [3H]TdR and [3H]proline of HLF respectively. RESULTS: The collagen synthesis increased markedly 24 h after exposure to both EA (0.05-4 mmol.L-1) and Cal (0.25-20 mumol.L-1), and that there was no obvious change in DNA synthesis. After 36-48-h exposure, both DNA and collagen syntheses decreased in the groups of EA (1, 2, and 4 mmol.L-1); the DNA synthesis was also suppressed in Cal groups in a concentration-dependent manner, whereas collagen synthesis decreased only in Cal (10 and 20 mumol.L-1). CONCLUSION: Extracellular Ca2+ influx into fibroblasts increased collagen production, However, the DNA synthesis was suppressed when the cytosolic Ca2+ was too high or too low.

Biological Transport, Active↗
PubMed1995

Residues in the second cysteine-rich region of protein kinase C delta relevant to phorbol ester binding as revealed by site-directed mutagenesis.

Phorbol esters bind with high affinity to protein kinase C (PKC) isozymes as well as to two novel receptors, n-chimaerin and Unc-13. The cysteine-rich regions present in these proteins were identified as the binding sites for the phorbol ester tumor promoters and the lipophilic second messenger sn-diacylglycerol. A 50-amino-acid peptide comprising the second cysteine-rich region of PKC delta, expressed in Escherichia coli as a glutathione S-transferase (GST)-fusion protein, bound [3H]phorbol 12,13-dibutyrate (PDBu) with high affinity (Kd = 0.8 nM). Using the cDNA of that cysteine-rich region as a template, a series of 37 point mutations was generated by site-directed mutagenesis, and the mutated proteins were analyzed quantitatively for binding of [3H]PDBu and, as appropriate, for binding of the ultrapotent analog [3H]bryostatin 1. Mutants displayed one of three patterns of behavior: phorbol ester binding was completely abolished, binding affinity was reduced, or binding was not significantly modified. As expected, five of the six cysteines as well as the two histidines involved in Zn2+ coordination are critical for the interaction of the protein with the phorbol esters. In addition, mutations in several positions, including phenylalanine 3, tyrosine 8, proline 11, leucines 20, 21 and 24, tryptophan 21, glutamine 27, and valine 38 drastically reduced the interaction with the ligands. The effect of these mutations can be rationalized from the three-dimensional (NMR) structure of the cysteine-rich region. In particular, the C-terminal portion of the protein does not appear to be essential, and the loop comprising amino acids 20 to 28 is implicated in the binding activity.

Amino Acid Sequence↗
PubMed1995

Construction of a chimeric antibody with therapeutic potential for cancers which overexpress c-erbB-2.

We describe the chimerization of a monoclonal antibody directed against the c-erbB-2 protein using a novel PCR method for cloning immunoglobulin variable region genes. We also describe the characterization of the chimera and show its potential use for treating cancers which overexpress the c-erbB-2 protein. The genomic DNA fragments of heavy and light chain variable genes were cloned by PCR using uniquely designed primers which allowed for isolation of genes containing functional promoters, signal and coding sequences. The chimeric genes were then constructed by linking variable regions of murine genes to human constant gamma 1 and kappa genes. Expression of the chimeric immunoglobulin genes resulted in production of properly assembled chimeric antibody with improved biological properties.

Animals↗
PubMed1995

Effects of tetrandrine and chlorpromazine on synthesis of collagen and hyaluronic acid in cultured human lung fibroblasts.

AIM: To study the effects of tetrandrine (Tet) and chlorpromazine (Chl) on synthesis of collagen and hyaluronic acid (HA) in cultured human lung fibroblasts (HLF). METHODS: The synthesis of collagen and HA was assessed by measuring the incorporation of [3H]proline and radioimmunoassay. RESULTS: Both Tet (5-80 mumol L-1) and Chl (10-40 mumol L-1) diminished the collagen synthesis in a concentration-dependent manner. The suppression was aggravated at 36-48 h. The HA content in the supernatant of culture also decreased gradually with the increasing dosage of Tet or Chl after 24-h exposure. There was no obvious toxic effect of Tet on HLF cells at 5-20 mumol L-1. CONCLUSION: Tet 5-20 mumol L-1 decreased the production of collagen and HA without obvious toxity on HLF, suggesting that Tet could be a hopeful anti-fibrosis drug.

Alkaloids↗
PubMed1993

Evaluation of the potential role of enzyme-linked immunosorbent assay in serodiagnosis of tuberculosis.

The serodiagnosis of tuberculosis was evaluated by means of enzyme-linked immunosorbent assay of IgG antibody to mycobacterial antigen 60. The study population consisted of 63 patients with active tuberculosis comprising 43 pulmonary tuberculosis, 15 tuberculosis pleurisy, four miliary tuberculosis, and one tuberculous lymphadenitis. The control group consisted of 48 patients embracing 8 cases of inactive pulmonary tuberculosis, 31 cases of pulmonary disorders other than tuberculosis, and nine normal persons. There was a significant difference in antibody titers of sera between patients of active tuberculosis and control group (P < 0.001). The sensitivity of the test for active pulmonary tuberculosis was 81.4% and the specificity was 85.4% (cutoff value 300 units). The sensitivity for all active tuberculosis was 61.9%. There was positive correlation between serum titer of active pulmonary tuberculosis and the extent of disease on chest radiography (r = 0.4, P < 0.01). A positive correlation was found between the titers of pleural fluids, and the corresponding sera in 15 patients (eleven tuberculous pleurisy and four nontuberculous controls) (r = 0.85, P < 0.001). Whether serum or pleural fluid, the positive rate of the assay for tuberculous pleurisy was relatively low. In conclusion, the A60 IgG ELISA test may be useful in serodiagnosis of pulmonary tuberculosis and assessment of the disease extent, although it might not yield a high sensitivity for tuberculous pleurisy.

Antibodies, Bacterial↗
PubMed1992

A study on the ecological habit of Armigeres subalbatus in Dawa area of the Mengshan Mountain in Shandong Province.

Armigeres subalbatus (A.s.) was reported in Shandong Province for the first time in 1965 and found in five counties of south Shandong including Pingyi, Linyi etc. in 1986. In Dawa area of the Mengshan mountain A.s. alults could be found in the first ten days of May, which increased in number in July, and become the dominant species in mosquito colonies in Aug. and Sept., then decreased gradually in number in Oct. and disappeared in Nov. There were two peaks of activity and blood-sucking behavior during the 24 hours of a day, one at dusk and the other at dawn. When the temperature dropped to 16 degrees C and below in the last ten days of Oct., the wigglers began their diapause period. The survival ratio reached 90.5% after 12 h freezing at -5 degrees C and none survived after 60 hours freezing. When the temperature rose to 17 degrees C and above the over-winterting larvae developed into adults, which could suck blood only at the temperature above 17.5 degrees C.

Animals↗
PubMed1990

Regulation of platelet-activating factor receptor and platelet-activating factor receptor-mediated biological responses by cAMP in rat Kupffer cells.

Treatment of cultured Kupffer cells with the beta-adrenergic agonist isoproterenol (10 microM) for a short period of time (30 min) attenuated the subsequent platelet-activating factor (PAF)-induced arachidonic acid release and cyclooxygenase-derived eicosanoid (e.g. thromboxane B2 and prostaglandin E2) production. This effect of isoproterenol was highly specific since the alpha-adrenergic agonist phenylephrine and the beta-adrenergic antagonist propranolol had no effect on the stimulatory effect of 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (AGEPC). The inhibitory effect of isoproterenol on the AGEPC-induced arachidonic acid release was demonstrated through the use of a specific beta-adrenergic subtype agonist and antagonist to be mediated by beta 2-adrenergic receptors on Kupffer cells. These inhibitory effects of isoproterenol can be mimicked by dibutyryl cAMP but not by dibutyryl cGMP, suggesting that a cAMP-dependent mechanism is likely involved in the regulatory action of isoproterenol. Ligand binding studies indicated that short term (i.e. 30 min) treatment of the cultured Kupffer cells with either isoproterenol or dibutyryl cAMP had no effect on the specific [3H]PAF binding. However, long term incubation (9-24 h) with dibutyryl cAMP caused down-regulation of the PAF receptors in rat Kupffer cells. Forskolin (0.1 mM), an adenylyl cyclase activator, down-regulated the surface expression of the AGEPC receptors more rapidly, decreasing the specific [3H]AGEPC binding by approximately 40% within 2 h. The receptor regulatory effect of dibutyryl cAMP and forskolin was time- and concentration-dependent. These observations suggest that a cAMP-dependent mechanism coupled with beta 2-adrenergic receptors may have important regulatory effects on the PAF receptor and post-receptor signal transducing mechanisms for PAF in hepatic Kupffer cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1990

Serological evaluation of Escherichia coli-expressed human T-cell leukemia virus type I env, gag p24, and tax proteins.

Three proteins (env, gag, and tax) encoded by the human T-cell leukemia virus type I (HTLV-I) genome were cloned and expressed in Escherichia coli. The env protein contained a substantial part of the gp46 domain and a majority of the p21e domain. The gag protein contained all of p24 and portions of p19 and p15. In addition to these two structural proteins, a full-length tax (p40X) construct was obtained. All three recombinant proteins were purified to near homogeneity. When used in an immunoblot assay, the three recombinant proteins detected antibodies in more HTLV-I antibody-positive patient sera than did the corresponding native proteins. Antibodies to at least two of these three different gene products were detected in 98.4% of adult T-cell leukemia patients, 100% of HTLV-I-associated myelopathy patients, 97.4% of asymptomatic carriers, and 94% of uncharacterized HTLV-I-positive patients. Antibody to recombinant tax was found in 4.9% of adult T-cell leukemia patients, whereas antibody to recombinant env could not be detected. These recombinant proteins from three different gene products may be useful in detecting or confirming the presence of antibodies to HTLV-I.

Adult↗
PubMed1990

[Psychosocial aspect of somatic complaints in patients after myocardial infarction].

The aim of this study was to explore the association between psychosocial variables and somatic complaints in terms of the biopsychosocial model. The analysis showed that both socioeconomic and psychological variables play a prominent role in the subjective complaints of coronary symptoms as follows: (1) Functional class: A low occupational index was found to be a predictor of much disability. Subjects with higher self-ratings of psychiatric symptoms (i.e. phobia, depression, interpersonal hypersensitivity), lower personal well-being (i.e. esteem, competence), and major social maladaptation had significantly more disability. (2) Chest pain: Patients with a higher morbidity of chest pain were more likely to be female, have less education, have more social maladjustment, and have less social support. Higher scores of psychiatric symptoms (i.e. anxiety, depression, hostility) and a perception of threatening by others were highly correlated with the severity of chest discomfort. Physicians should be aware of the ways in which psychosocial and biomedical variables may interact at many levels, especially for the patients with unexplained physical symptoms or social dysfunction.

Adaptation, Psychological↗
PubMed1985

Coxsackievirus B3: primary structure of the 5' non-coding and capsid protein-coding regions of the genome.

The nucleotide sequence from the 5' terminus to nucleotide 3822 has been determined for the genome of the enterovirus, coxsackievirus B3 (CB3). This region encompasses the 5'-terminal 738 nucleotide non-coding sequence and the region which codes for the four viral capsid proteins and for the initial products of the P2 region. Regions in the 5' non-translated RNA sequence which may be involved with a structural and/or regulatory role are discussed.

Amino Acid Sequence↗
PubMed1983

Studies on avian erythrocyte metabolism. XIII. Changing organic phosphate composition in age-dependent density populations of chicken erythrocytes.

These studies were performed to determine whether the erythrocytes (RBC's) of chickens are able to alter the concentrations of organic phosphates, particularly inositol pentakis (dihydrogen phosphate) (inositol-P5), in response to anemia. Acute anemia with 33.5% reticulocytes (retics) in the peripheral blood of 4-month-old White Leghorn cockerels was produced after two successive days of controlled bleeding. Five populations of RBC's were prepared from blood of these anemic birds based upon age-dependent density by angle rotor centrifugation. The relative increase in age of Fraction 1 (younger cells) through Fraction 5 (oldest cells) was verified by increased hemoglobin concentration and decreased retic count and cell volume. The acid aqueous-soluble phosphates from each RBC fraction were extracted, fractionated by ion exchange column chromatography, and the concentration of inorganic phosphate (Pi), adenosine triphosphate (ATP), and inositol-P5 quantitated by wet-ash phosphate analysis. Determination of Pi, ATP, and inositol-P5 in Fraction 1 (younger cells, 7.4% retics) from the initial (Day 1) blood withdrawn gave 4.3, 5.7, and 18.6 mumoles Pi/ml RBC, respectively. On Day 4 of controlled-bleeding, Pi, ATP, and inositol-P5 concentrations in Fraction 1 (95.1% retics) were 12.7, 10.6, and 12.3 mumoles Pi/ml RBC, respectively. On Day 11, after 1 week recovery from controlled-bleeding, the values for Pi, ATP, and inositol-P5 in Fraction 1 (37.7% retics) were 5.0, 5.4, and 19.0 mumoles Pi/ml RBC, respectively, which were similar to the values before bleeding.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3-Diphosphoglycerate↗
PubMedDate not supplied

Comparison of the experimental BOLD signal change in event-related fMRI with the balloon model.

Event-related functional MRI (ER-fMRI) based on both blood oxygenation level-dependent (BOLD) contrast and cerebral blood flow (CBF) contrast has been developed to study the human brain response to transient stimulation. A balloon model has been developed and used in understanding the relationship between changes in CBF and in the BOLD signal in block-designed fMRI. In this report, the balloon model was used to interpret experimental event-related fMRI. Using experimental data acquired from CBF-based ER-fMRI as an input function in the balloon model, simulated BOLD signal changes were obtained. The simulated time course of the BOLD signal changes was directly compared with the experimentally acquired data. A chi-square (chi(2)) test showed excellent correlation between the simulated and experimental data (alpha <or= 0.05). Our results have demonstrated that the balloon model is useful in interpreting the transient features of the experimental data from the ER-fMRI studies.

Cerebrovascular Circulation↗
PubMedDate not supplied

Acute heat injury to the normal swine rectum.

Intracavitary hyperthermia was applied to the rectum of normal pigs at 43 degrees, 44 degrees, 45 degrees, 46 degrees, 47 degrees and 48 degrees C for 30 min. A score of temperature-induced histological changes of each specimen was made 48 h after heating. The scores from each specimen and temperature were used for regression analysis. Judging from the regression lines of the scores obtained for rectum and oesophagus, we conclude that the thermosensitivity of the rectum is about 1 degree C higher than that of the oesophagus. It suggested that 43 degrees C/30 min could be a safe dose for normal rectum. The thermosensitivity of swine rectum is discussed.

Animals↗