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Biomedical subjects

C Huang

Publications and source records attributed to C Huang.

At least 451 records · Page 25Linked to original sources
PubMed1993

[Clinical application of the thoracic balloon for postpneumonectomy patients].

Pneumonectomy may result in complications such as continuous intrathoracic bleeding and mediastinal shift. We used a thoracic balloon made of silicone rubber in 15 postpneumonectomy patients in an attempt to prevent such complications. Two types of thoracic balloons were used in our series. Type 1 thoracic balloon is a simple balloon requiring cooperation with a drainage tube, and Type 2 is a combination balloon and drainage tube. During surgery, air was injected into the thoracic balloon through an air filter. After removal of the thoracic balloon, infusion of sulfur hexafluoride, SF 6, into the thoracic cavity was performed on the 7th to 10th postoperative days. Placement of thoracic balloons in the pleural space after pneumonectomy is a simple, safe and useful method of preventing both intrathoracic bleeding and mediastinal shift.

Aged↗
PubMed1993

Ambient-temperature-stable molecular biology reagents.

We have processed biological materials to generate several reagents that are ambient temperature stable and ready to use. Stabilized biomolecules in a glassy matrix of carbohydrate polymers offer water-soluble reagents for complex molecular biology applications. This approach is particularly useful for reagent systems composed of enzymes, nucleotides and other components dispensed in single-use aliquots. Reconstitution of the glassy matrix delivers buffered enzymes and/or nucleotides for restriction, modification, sequencing and/or amplification of nucleic acids. These ambient-temperature-stable reagents allow a high level of reproducibility as they minimize the potential for pipetting errors. They also provide advantages in shipping, storage and subsequent handling. Added convenience includes elimination of setup time, cross contamination and refrigeration. Applications of ambient-temperature-stable biological reagents for routine molecular biology methods are presented.

Biotechnology↗
PubMed1993

The effects of hybridoma growth factor in conditioned media upon the growth, cloning, and antibody production of heterohybridoma cell lines.

Interleukin 6 (IL-6)/hybridoma growth factor (HGF) has been shown to be the requirement for growth of murine hybridomas in vivo or in vitro. In this paper, two kinds of conditioned media (CM) from the culture supernatants of a human fibroblast cell line CRL1506 and a cloned Epstein-Barr virus (EBV) transformed human lymphoblastoid cell line (LCL) N23 were found to have IL-6 activity by strongly promoting the growth, antibody secretion (increase of one- to three-fold), and cloning efficiencies of heterohybridomas secreting human monoclonal anti-hemorrhagic fever with renal syndrome virus antibodies and LCL. Since these CM contained no detectable IL-2, and IL-4 had no effects on the growth of the cell lines, IL-6 was considered to be the main active component of the CM responsible for promoting hybridoma growth. This effect was further confirmed by IL-6-dependent cell line 7TD1 bioassay (IL-6 activity in the CM ranging from 1,000 to 10,000 units/ml). Moreover, we successfully established four EBV-transformed lymphoblastoid cell lines at single-cell level by adding an equal volume of CRL1506-CM to 10% FCS-RPMI1640 in limiting dilution. Finally, it is worth noting that the sensitivity of the heterohybridomas to the two kinds of CM was not the same and was not consistent with that of their parental myeloma cell lines. Thus, it suggests that the CM might contain more than one factor, and the choice of proper conditioned media should be very useful for human monoclonal antibody production.

Animals↗
PubMed1992

Molecular cloning and sequence analysis of the gene coding for the 57-kDa major soluble antigen of the salmonid fish pathogen Renibacterium salmoninarum.

The complete sequence coding for the 57-kDa major soluble antigen of the salmonid fish pathogen, Renibacterium salmoninarum, was determined. The gene contained an opening reading frame of 1671 nucleotides coding for a protein of 557 amino acids with a calculated M(r) value of 57,190. The first 26 amino acids constituted a signal peptide. The deduced sequence for amino acid residues 27-61 was in agreement with the 35 N-terminal amino acid residues determined by microsequencing, suggesting the protein is synthesized as a 557-amino acid precursor and processed to produce a mature protein of M(r) 54,505. Two regions of the protein contained imperfect direct repeats. The first region contained two copies of an 81-residue repeat, the second contained five copies of an unrelated 25-residue repeat. Also, a perfect inverted repeat (including three in-frame UAA stop codons) was observed at the carboxyl-terminus of the gene.

Amino Acid Sequence↗
PubMed1992

Identification of phosphatidylcholine-selective and phosphatidylinositol-selective phospholipases D in Madin-Darby canine kidney cells.

Intact cells and cell-free systems were employed to characterize phospholipase D (PLD) activity in Madin-Darby canine kidney (MDCK) cells. In cells prelabeled with [3H]glycerol, 12-O-tetradecanoylphorbol-13-acetate (TPA) elicited phosphatidylcholine (PC) hydrolysis by PLD, as shown by the prolonged formation of [3H]phosphatidylethanol (PEt) and an accompanying decrease in [3H]PC. In contrast, bradykinin elicited rapid formation of [3H]PEt (approximately 1 min) accompanied by a decrease in [3H]phosphatidylinositol (PI). When the agonists were administered simultaneously, [3H]PEt formation was biphasic. In cells prelabeled with [3H] choline, at times less than 1 min, bradykinin failed to induce significant change in [3H]choline release. Bradykinin-induced formation of [3H]PEt in the [3H]glycerol-labeled cells was strictly dependent on extracellular Ca2+, whereas TPA-induced formation of [3H]PEt did not require extracellular Ca2+. Cell-free assays for PLD were used to assess the enzyme location, substrate specificity, and cofactor requirements. The PC-PLD activity (PEt formation) against [3H]stearoyl-PC was primarily localized in the 440 x g pellet (membrane- and nuclear-associated), preferred PC as a substrate, required detergent, and was not influenced by Ca2+ at low concentrations but was inhibited by Ca2+ in excess of 0.5 mM. The PI-PLD activity against [3H]stearoyl-PI was found largely in the 100,000 x g supernatant (cytosol), was strictly Ca(2+)-dependent, and did not require detergent. From these data, we conclude that MDCK cells contain two PLD subtypes: 1) a membrane-associated, PC-selective enzyme that responds to TPA resulting in prolonged hydrolysis of PC (the PC-PLD is Ca(2+)-independent, but requires detergent); 2) a cytosolic, PI-selective enzyme that responds rapidly but transiently to bradykinin (the PI-PLD requires Ca2+ but not detergent).

Animals↗
PubMed1992

Phospholipase D activity in nontransformed and transformed fibroblasts.

Rat embryo fibroblasts (REF52 cells) and the simian virus 40 transformed derivative (WT6 Ag6) were employed to characterize phospholipase D (PLD) activity in normal and transformed cells. In cells prelabeled with [3H]myristic acid or [3H]glycerol and treated with 12-O-tetradecanoylphorbol-13-acetate (TPA, 50 ng/ml medium) or vasopressin (VP, 100 ng/ml medium) in the presence of ethanol, the formation of labeled phosphatidylethanol (PEt) was 3- to 5-fold higher in REF52 cells than in the transformed cells. The transphosphatidylation of phosphatidylcholine (PC) to PEt was further examined in cell-free assay systems. Results demonstrated that the formation of PEt in the cell-free assays was dependent on the mode of substrate presentation and the source of the PC. With endogenous membrane-bound substrate, the formation of [3H]myristoyl-PEt was 5-fold higher in homogenates derived from normal cells as compared to transformed cell homogenates. In experiments using exogenous labeled PC isolated from either REF52 or transformed cells as substrate, cell-free PLD activity differed greatly with regard to the source of the PC. The formation of PEt from REF52-derived PC was approx. 4-fold higher as compared to PEt formed with PC derived from the transformed cells, irrespective of enzyme source. The results demonstrate that PLD in intact nontransformed fibroblasts is activatable by TPA and VP to a greater extent than in the transformed counterpart. The results from cell-free assays suggest that PLD activity is more dependent on the type of PC substrate than on the source of the enzyme.

Animals↗
PubMed1992

Interleukin-1 induces protein tyrosine phosphorylation in T cells.

Interleukin (IL)-1 alpha activates multiple signal transmission pathways in the T helper type 2 cell line, D10A, and these pathways are linked to two separate IL-1 receptors (IL-1R). In the present report we show that IL-1 induces the activation of tyrosine kinase in these cells, leading to tyrosine phosphorylation of a subset of proteins of 38, 75, 97 and 115 kDa. This type of phosphorylation is prevented by a monoclonal antibody directed against the 80-kDa IL-1R and by tyrphostins which are specific inhibitors of tyrosine kinases. In addition, this inhibitor blocks IL-1-and IL-2-induced proliferation in D10A cells as well as the c-myc and c-myb proto-oncogene mRNA expression in response to IL-1. Interestingly, the inhibitor of cAMP-dependent kinase, H-8, only blocks IL-1-induced c-myb, but not c-myc mRNA expression. Altogether, our results demonstrate that the activation of a tyrosine kinase(s) is an early and major event that happens after IL-1/IL-1R interaction, leading to an increase in intracellular cAMP which results in c-myb and IL-5 mRNA expression. Independent of cAMP, by tyrosine phosphorylation of specific substrates IL-1 also induces c-myc and IL-6 mRNA expression and cellular proliferation.

Animals↗
PubMed1992

Automated site-directed drug design using molecular lattices.

Receptor-based drug design is predicated on the knowledge of the structure of a target receptor and the principles of molecule recognition. The objective is to produce a wide diversity of structures that are sterically and electrostatically complementary to a specified receptor site. Many drug-receptor interactions are controlled by a few key receptor groups. This observation leads to a design approach in which one focuses on chemical fragments that putatively interact with the key receptor groups. There then remains the difficult task of joining the fragments into molecular structures that match the spatial patterns of recognition forces in the receptor site. In this paper, we describe a new modeling program, BUILDER, that combines database searching techniques and structure generation algorithms within an interactive graphics modeling environment (MidasPlus). A novel tool for process communication (delegate) is introduced and examples of its use are given. To demonstrate the functionality of the package and its ability to produce novel structures, we examine the active site of HIV-1 protease.

Algorithms↗
PubMed1992

Study of the actions of human recombinant erythropoietin on rat renal haemodynamics.

1. Studies were undertaken to examine the effect of acute and chronic administration of human recombinant erythropoietin on kidney cortical and papillary perfusion in the anaesthetized rat using laser-Doppler flowmetry. 2. Thirty minutes after erythropoietin (50 and 150 units/kg intravenously), blood pressure, cortical perfusion and papillary perfusion were unchanged. 3. In animals treated chronically with erythropoietin over 7 days (three doses of 150 units/kg subcutaneously) blood pressure was similar to that of vehicle-treated animals, whereas cortical perfusion and papillary perfusion were reduced by 23% and 20%, respectively (both P < 0.05), and the packed cell volume (51.1 +/- 0.7%) was significantly (P < 0.01) greater than in vehicle-treated animals (46.2 +/- 0.6%). 4. Bolus doses of vasopressin and phenylephrine increased blood pressure (by between 10% and 40%) and decreased cortical and papillary perfusion (by between 10% and 20%), while angiotensin II caused similar increases in blood pressure and decreases in cortical perfusion but not papillary perfusion. The magnitude and pattern of these responses were comparable after both acute and chronic administration of erythropoietin. 5. Erythropoietin given acutely at therapeutic levels has a marginal effect on cortical and papillary perfusion. However, the chronic treatment indicated that there was a sustained reduction in both cortical and papillary perfusion, reflecting a vasoconstriction. This reduction in renal haemodynamics could contribute to the increase in blood pressure observed when this hormone is administered in man.

Animals↗
PubMed1992

VH-gene representation in autoantibodies reflects the normal human B-cell repertoire.

The recurrence in the V-gene repertoire of individual germline VH genes can now be extended from the restricted B-cell populations of the fetus, autoantibodies and B-cell malignancies to the expressed V-gene repertoire of normal adults. Why the human B cell preferentially utilizes these individual VH genes remains speculative. However, it is apparent that the population of VH genes used to encode autoantibodies reflects the normal expressed repertoire (Fig. 7). Even so, the overrepresentation of other V genes such as Dxp'1 in anti-DNA antibodies and the presence of somatic mutation in the pathogenic autoantibodies of autoimmune disease continues to suggest an antigenic influence on V-gene selection. We postulate that only a fraction of available germline V genes are utilized in the expressed repertoire, and that polyspecificity of naturally occurring antibodies and somatic mutation of CDR3 compensate for the loss of diversity entailed by the limited use of the potential repertoire. The mechanisms by which germline genes become pathogenic remains unclear but they presumably relate to mutation, loss of regulatory control or perhaps environmental factors (Isenberg et al. 1992). What then are the mechanisms which lead to escape of these VH genes from normal control? What antigenic drive if any produces anti-DNA specificity in SLE? Why indeed is the expressed repertoire using only a fraction of the available germline? To answer these questions, further study of the V-gene repertoire of selected populations of antigen-binding cells and of pathogenic IgG autoantibodies is necessary and is ongoing. The contribution of individual V genes to antigen binding and idiotype is also being dissected and promises to yield important information about the relative contribution of VH genes to autoimmunity.

Adult↗
PubMed1992

Immunoglobulin heavy chain gene expression in peripheral blood B lymphocytes.

cDNA libraries for IgM heavy chain variable regions were prepared from unmanipulated peripheral blood lymphocytes of two healthy people. Partial sequencing of 103 clones revealed VH gene family use and complete CDR3 and JH sequences. The libraries differed in the two subjects. In one person's cDNA the VH5 family was overexpressed and the VH3 family underexpressed relative to genomic complexity. In the second person's cDNA, VH3 was most frequently expressed. In both libraries, JH4 was most frequent. VH segments of several clones were closely related to those in fetal repertoires. However, there was also evidence of mutation in many cDNAs. Three clones differed from the single nonpolymorphic VH6 germline gene by 7-13 bases. Clones with several differences from VH5 germline gene VH251 were identified. CDR3 segments were highly diverse. JH portions of several CDR3's differed from germline JH sequences. 44% of the clones had DH genes related to the DLR and DXP families, most with differences from germline sequences. In 11 DLR2-related sequences, several base substitutions could not be accounted for by polymorphism. Thus, circulating IgM-producing B cell populations include selected clones, some of which are encoded by variable region gene segments that have mutated from the germline form.

Amino Acid Sequence↗
PubMed1992

Transcription of the human ferredoxin gene through a single promoter which contains the 3',5'-cyclic adenosine monophosphate-responsive sequence and Sp 1-binding site.

We have investigated the functional elements involved in cAMP-stimulated transcription of the human ferredoxin gene. Unlike the bovine gene, the human gene lacked a second upstream RNA initiation site as demonstrated by sequence analysis of the exon boundary, lack of upstream RNA, and analysis of the promoter. The presence of a single promoter was determined by testing the ability of various gene segments to drive the expression of the chloramphenicol acetyltransferase gene after transfection into a mouse adrenal cell line Y1. Full promoter activity was conferred by a DNA fragment spanning -209 to +55, although the -94 to +55 fragment already provided some promoter activity. Transcription from the -94 to +55 segment was stimulated by 2-fold when 8-bromo-cAMP was added to the cell. Footprinting analyses showed two GC boxes at -50 to -70 and -87 to -108 were protected by proteins from both Y1 and HeLa cells. Competition experiments showed that a protein with a recognition sequence indistinguishable from Sp1 bound to these sites. When connected to a heterologous TATA box, the sequence at -76 to -42, which contained the proximal GC box, was able to confer a high level of basal transcription and cAMP stimulation. This sequence does not show sequence homology with the known cAMP-responsive element. Mutations or deletion of the Sp 1-binding site showed diminished basal transcription and defined the cAMP responsive sequence to be from -76 to -62. Therefore the cAMP-responsive sequence of the human ferredoxin gene was located at -76 to -62, which was adjacent to the Sp 1-binding site.

Amino Acid Sequence↗
PubMed1992

A case-control study of dietary factors in patients with lung cancer.

A case-control study was designed to investigate association of dietary factors with the risk of lung cancer in Sichuan, China. The cases consisted of 135 patients with preinvasive lung cancer which had been confirmed with histopathology, fiber bronchoscope, CT and X-ray film in three provincial hospitals in the recent one year. Controls were healthy subjects who went to one of these hospitals for health check-up; patients with pulmonary diseases was excluded. Controls were matched to cases for sex and age with a ratio of 1:1. Nutrient intakes, the eating habit and other relevant factors were investigated. The data analyzed with the conditional logistic regression model indicated that dietary beta-carotene intakes had a significantly inverse association with the risk of lung cancer. Vitamin C had a less significantly inverse association with the risk. Association of protein, fat, energy, retinol intakes or diet-balance index with the risk was not significant. Association of tea, alcohol, garlic or mushroom, respectively, with the risk was also not observed. Consumption of more processed foods and deep-fried foods were found to be risk factors. Smoking and air pollution from coal burning stoves were also observed as independent risk factors of lung cancer in the present study. The mental stress incidence in the case was significantly higher than that in the control.

Adenoma↗
PubMed1992

[High level of tumor necrosis factor alpha activity of plasma and serum from acute phase hemorrhagic fever with renal syndrome].

The level of TNF-alpha activity of plasma and serum from HFRS acute phase patients was investigated. The level of TNF (tumor necrosis factor) activity of plasma and serum from acute phase patients was higher than that of plasma and serum from convalescent phase patients or from normal group. The higher TNF activity of plasma or serum from acute phase patients was due to TNF-alpha, because the TNF activity was almost completely inhibited by polyclonal mouse serum against rHuTNF-alpha. Also, the increase in TNF-alpha positive ratio of PBMC from acute phase HFRS patients was found as compared to convalescent phase patients or to normal group. All these results strongly suggest that high level of TNF-alpha activity of plasma and serum may be involved in the development of clinic symptoms and pathological lesions during the course of HFRS disease.

Hemorrhagic Fever with Renal Syndrome↗
PubMed1992

[A case of mediastinal liposarcoma].

Primary liposarcomas of the mediastinum are rare neoplasms comprising only 0.13-0.75% of mediastinal tumors. We report a case of liposarcoma arising in the right posterior mediastinum. A 74-year-old man without symptoms was admitted to our hospital for evaluation of an abnormal shadow on chest roentgenogram. Computed tomogram (CT) and magnetic resonance (MR) imaging revealed a mediastinal tumor. The tumor was surgically removed, and the diagnosis of well-differentiated liposarcoma was established. MR imaging was superior to CT in evaluation of tumor extent, but not in differential diagnosis as liposarcoma or lipoma.

Aged↗