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Biomedical subjects

L Chen

Publications and source records attributed to L Chen.

At least 1,405 records · Page 78Linked to original sources
PubMed1990

Epiglottic laryngoplasty after extended hemilaryngectomy for glottic cancer.

This paper reports the experience in the application of modified epiglottic laryngoplasty in 20 extended hemilaryngectomies for glottic carcinoma. The Kambic-Sedlacek-Tucker (K-S-T) technique using the epiglottis in glottic reconstruction can lead to early decannulation with an excellent airway, but a wide glottis formed after operation will increase the chance of aspiration and poor voice. Sphincteric function preservation of the glottis is a key point to success in partial laryngectomy. In order to prevent aspiration and to improve the quality of voice, the reconstructive technique as modified as follows: (1) Lateral margin of the epiglottis was sutured to the cricoid. (2) The superior edge of the epiglottis was lowered to reconstruct the ventricular band. (3) A cut was made at the anterior aspect of the epiglottis to reconstruct the anterior commissure. It is the experience of the authors that modified epiglottic laryngoplasty is better than the K-S-T technique for preservation of laryngeal function after extended hemilaryngectomy.

Aged↗
PubMed1990

[Pest control and yield increase of areca by root-zone application of carbofuran in admixture with fertilizers].

The result of our experiment has shown that by root-zone application of carbofuran in admixture with fertilizers to Areca in spring the serious pest Tirathaba rufivena can be controlled for 4 months during flowering and young fruiting stage and the yield can increase by 50%. The final residual amount of carbofuran in fruits is below 0.1-0.01 ppm or too low to be examined, and there is no decrease in total alkaloid content in fruits.

Alkaloids↗
PubMed1990

Overexpression of matrix Gla protein mRNA in malignant human breast cells: isolation by differential cDNA hybridization.

Genetic alterations are involved in the development of human breast cancer. We sought to isolate genes that are differentially expressed or suppressed in cultured human breast carcinoma cells as compared to cultured normal human breast epithelial cells by employing differential screening of selected cDNA libraries. Analysis of several clones thus isolated revealed that the matrix Gla protein (MGP) gene is overexpressed in the breast cancer cell line 600 PEI, though is transcribed at lower levels in most other mammary derived cultures. MGP requires vitamin K dependent gamma-carboxylation for its known function and thus can be inhibited by vitamin K antagonists. This raises the possibility that MGP may be among those factors that when inhibited by vitamin K antagonists reduce metastases in experimental models. Among the gene whose transcription is consistently suppressed upon mammary transformation were fibronectin and the type I keratin, K14. Differential cDNA screening therefore is an effective method of identifying genes involved in various aspects of mammary cell transformation.

Base Sequence↗
PubMed1990

[Delayed intracranial aneurysm of left atrial myxoma--a case report].

Although embolism is known as a common complication in the early growing stage of atrial myxoma, development of further neurologic disorders after the removal of tumor is rarely encountered. Arterial aneurysm formation and metastatic tumor growth represent the two disorders that had been reported in the literature. Based on the pathogenesis of hematogeneous disseminating, atrial myxoma may lodge its fragment or its adherent thrombus on intracranial vessels to produce cerebral infarct. Besides, several reports have indicated that myxoma emboli in the cerebral vessels may invade the vessel wall to produce delayed disorders. Embolization from atrial myxoma is now recognized as a potentially treatable cause of cerebral infarct. However, the long-term course following resection of the tumor remain complicated, partly due to these inconsistent delayed complications, or the therapeutic dilemma. We report a case with delayed intracranial aneurysm formation and reviewed the literature. A 67-year old woman with a past history of left cerebral infarction was transferred to our hospital for further evaluation of her gross hematuria. Infarction of the left kidney was then demonstrated by angiography. A left atrial myxoma was found in a echocardiographic screen, and the patient received a successful resection of the myxoma subsequently. Unfortunately, three episodes of stroke developed in a half year after the operation of the cardiac myxoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

[Analysis of cellular fatty acids of Enterobacteria species by gas chromatography-mass spectrometry].

Cellular fatty acid compositions of 15 Enterobacteria were analyzed by gas chromatography-mass spectrometry(GC-MS). About 30 fatty acids were detected in chromatograms, and 13 of them were chemically identified, e.i. C11:0, C12:0, C13:0, C14:0, C15:0, 2OH-C14:0, 3OH-C14:0, C16:1, C16:0, aC17:0, delta C17:0, C18:1 and C18:0. The major cellular fatty acids in all fifteen species were C16:0, C18:1, C15:0, C14:0, C16:1, C13:0, 3OH-C14:0 and C18:0. The cellular fatty acids of Enterobacteria species were characterized by normal straight-chain saturated acids and monounsaturated acids, of which the most abundant fatty acid was C16:0. 3OH-C14:0 was found in all strains of Enterobacteria, whereas 2OH-C14:0 was only found in strains of Serratia species. Other unknown compositions also would have been certain characteristics for bacteria. The present paper would provide some of useful reference data for chemotaxonomy and molecular microbiology of Enterobacteria.

Enterobacteriaceae↗
PubMed1990

[Experimental studies on treating anti-anaphylactic asthma with a qingfei bushen decoction].

On the basis of satisfying clinical effects of Qingfei Bushen Decoction, the authors carried out experimental studies with animals on anti-anaphylactic asthma with the decoction (200% condensed) to probe into the effective mechanism. The experimental results showed that the condensed decoction could effectively suppress rats' passive cutaneous anaphylaxis and guinea pigs' anaphylactic asthma allergized by egg protein. The results also showed that the condensed decoction obviously resisted the guinea pigs' bronchial spasm induced by histamine and acetylcholine, and it could significantly promote the multiplication of rats' thymus gland. Thymus gland multiplication and immunomodulating action are also discussed in the paper.

Acetylcholine↗
PubMed1989

Plasma desorption mapping of the tryptic digest of 23-kDa recombinant human growth hormone.

Plasma desorption mass spectrometry has been used to map the tryptic fragments from the 23-kDa recombinant human growth hormone protein. The unfractionated tryptic digest was adsorbed directly onto a nitrocellulose sample foil and mass spectra were obtained in both the positive and the negative ion mode. The adsorbed sample was then washed with deionized water and its mass spectrum was again obtained. The latter spectrum revealed tryptic fragments that were not observed in the spectra of the unwashed sample, which can be attributed (to some extent) to the removal of hydrophilic residues during washing. From this study a protocol, aimed at the complete mapping of tryptic fragments, is outlined.

Amino Acid Sequence↗
PubMed1989

Leiomyoma of the ovary--a case report.

Primary ovarian leiomyoma is rare. About 40 cases have been reported in the literature. A case report of leiomyoma of ovary and the literature review was presented.

Adult↗
PubMed1989

Murine elongation factor 1 alpha (EF-1 alpha) is posttranslationally modified by novel amide-linked ethanolamine-phosphoglycerol moieties. Addition of ethanolamine-phosphoglycerol to specific glutamic acid residues on EF-1 alpha.

Elongation Factor 1 alpha (EF-1 alpha), an important eukaryotic translation factor, transports charged aminoacyl-tRNA from the cytosol to the ribosomes during poly-peptide synthesis. Metabolic radiolabeling with [3H] ethanolamine shows that, in all cells examined, EF-1 alpha is the major radiolabeled protein. Radiolabeled EF-1 alpha has an apparent Mr = 53,000 and a basic isoelectric point. It is cytosolic and does not contain N-linked oligosaccharides. Trypsin digestion of murine EF-1 alpha generated two major [3H]ethanolamine-labeled peptides. Three peptides were sequenced and were identical to two distinct regions of the human EF-1 alpha protein. Blank sequencing cycles coinciding with glutamic acid in the human cDNA-derived sequence were also found to release [3H]ethanolamine, and compositional analysis of these peptides confirmed the presence of glutamic acid. Dansylation analysis demonstrates that the amine group of the ethanolamine is blocked. These results indicate that EF-1 alpha is posttranslationally modified by the covalent attachment of ethanolamine via an amide bond to at least two specific glutamic acid residues (Glu-301 and Glu-374). The hydroxyl group of the attached ethanolamine was shown by mass spectrometry and compositional analysis, to be further modified by the addition of a phosphoglycerol unit. This novel posttranslational modification may represent an important alteration of EF-1 alpha, comparable to the regulatory effects of posttranslational methylation of EF-1 alpha lysine residues.

Amino Acid Sequence↗
PubMed1989

Purification of the Escherichia coli secB gene product and demonstration of its activity in an in vitro protein translocation system.

Mutations in the Escherichia coli secB gene lead to protein export defects in vivo (Kumamoto, C.A., and Beckwith, J. (1985) J. Bacteriol. 163, 267-274). To demonstrate directly the participation of the secB gene product (SecB) in protein export, SecB was purified, and its effects on in vitro protein translocation were analyzed. SecB was purified from soluble extracts of a strain that overproduced it, by ammonium sulfate precipitation, DEAE-cellulose chromatography, and differential precipitation at acid pH. The chromatographic behavior on gel filtration columns indicated apparent molecular masses of approximately 90 kDa for both purified SecB and SecB in cytosolic extracts of wild type cells. When added to a translocation mixture, purified SecB stimulated pro-OmpA translocation into membrane vesicles. SecB also suppressed the thermoinduced defect in translocating activity of membranes derived from a secY24 mutant. The results of these in vitro studies and of previous in vivo studies demonstrate that SecB plays a direct role in normal protein export in E. coli.

Bacterial Outer Membrane Proteins↗
PubMed1989

Serum stimulation of quiescent human fibroblasts induces the synthesis of tissue factor mRNA followed by the appearance of tissue factor antigen and procoagulant activity.

Expression of the gene for tissue factor, the cell-surface initiator of blood coagulation, was examined by stimulating growth-arrested human fibroblasts with serum and measuring changes in the cellular content of tissue factor mRNA, antigen, and activity. Maximum tissue factor mRNA levels were reached within 1 h following serum induction and slowly declined to basal levels from 24 to 48 h after stimulation. The appearance of the tissue factor mRNA was followed by an increase in tissue factor antigen and activity. The parallel rise in antigenically positive protein and procoagulant activity was first observed about 2 h after serum stimulation with a peak at 12 h followed by a slow decline during the next 36 h. The serum-induced synthesis of the tissue factor mRNA was independent of de novo protein synthesis as demonstrated by the increased tissue factor mRNA levels generated in the presence of cycloheximide. The results of this study suggest that the synthesis of tissue factor in human fibroblasts is regulated principally at the level of transcription. In one strain of fibroblasts the activity/antigen ratio, during the period of maximum synthesis, was indistinguishable from that of tissue factor which had been immunoaffinity purified from human brain and reconstituted into phospholipid vesicles. However, during serum starvation the activity/antigen ratio in these cells was significantly reduced. Western blot analysis revealed that in serum-starved cells there was an accumulation of truncated forms of the tissue factor antigen while in the serum-stimulated cells only the full-length antigen was observed.

Blood↗
PubMed1989

Effects of inhibitors of membrane signal peptide peptidase on protein translocation into membrane vesicles.

The effect of the removal of signal peptides after cleavage of precursor molecules by the signal peptidase I was examined in an in vitro translocation system with Escherichia coli membrane vesicles. The translocation of periplasmic alkaline phosphatase precursors was significantly inhibited by the protease inhibitors antipain, elastatinal and leupeptin. Antipain and leupeptin enhanced the translocation of precursors of outer membrane protein OmpA, but inhibited the processing. However, antipain did not inhibit the processing of precursors mediated by signal peptidase I in the soluble form. Moreover, the inhibition by antipain was not due to the disruption of membrane integrity, but occurred during the process of protein translocation. Since these small peptide inhibitors are known to inhibit membrane protease IV, a signal peptide peptidase, these results suggest that the hydrolysis of signal peptides is an important step in the recycles of the overall translocation process, and that the prevention of degradation of signal peptides feedback inhibits the preceding steps in the translocation pathway.

Alkaline Phosphatase↗
PubMed1989

Molecular and cellular responses of islets during perturbations of glucose homeostasis determined by in situ hybridization histochemistry.

We have evaluated in situ hybridization histochemistry as a means of estimating simultaneously the level of prohormone mRNA and the dimensions of rat pancreatic islets. Localization of the 27-mer 32P-labeled oligonucleotide probes for rat proinsulin I, glucagon, and prosomatostatin I corresponded with localization of antibodies to the three hormones. In normal rats subjected to chronic hyperglycemic clamping, the density of the proinsulin mRNA signal increased 54%, islet size and number increased approximately 100%, while proglucagon mRNA signal was reduced 81%. Resection of 50% of the pancreas increased proinsulin mRNA 36% and proglucagon mRNA 500%; islet area doubled and islet number increased 50%. In 150-day-old diabetic ob/ob mice, there was an 18-fold expansion in islet area, a 4-fold increase in islet number, but no increase in insulin gene expression. In insulin-dependent streptozotocin-treated diabetic rats, islet area and number were profoundly reduced; insulin deprivation failed to raise proinsulin mRNA in surviving beta cells above control levels. Proglucagon mRNA was high despite the hyperglycemia but was reduced by insulin within 1 hr, suggesting that insulin regulates glucagon gene expression or is required for its regulation by glucose. In situ hybridization of rat islets provides a valid semiquantitative index of insulin and glucagon biosynthesis and of islet dimensions and reveals that normal but not diabetic islets meet increased insulin demand by increasing both number and biosynthetic activity of beta cells.

Animals↗