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Biomedical subjects

Y Yuan

Publications and source records attributed to Y Yuan.

At least 145 records · Page 8Linked to original sources
PubMed1999

[Effect of hypoxia on proliferation and differentiation of the pulmonary vascular pericytes].

OBJECTIVE: To study the effect of hypoxia on proliferation and differentiation of the pulmonary vascular pericytes (PC). METHODS: Cell culture, (3)H-thymidine incorporation ((3)H-TdR), immunocytochemistry and image analysis methods were used. RESULTS: It was found that the (3)H-thymidine incorporation, the expression amounts of proliferating cell nuclear antigen (PCNA) and alpha-smooth muscle actin (alpha-SM-Actin) in direct hypoxia (H) group was 2.16 times (P < 0.01), 1.16 times(P < 0.01) and 1.11 times (P < 0.05) that of normoxia (N) group, in hypoxic endothelial cell conditioned medium (HECCM) group was 1.8 times (P < 0.01), 1.15 times (P < 0.01) and 1.12 times (P < 0.05) that of normoxic endothelial cell conditioned medium (NECCM) group. CONCLUSIONS: It was suggested that hypoxia can stimulate pulmonary artery endothelial cells (PAEC) to secrete some growth factors to enhance PC proliferation and transformation of smooth muscle-like cells.

Actins↗
PubMed1999

[Reinfusion of autologous shed blood after joint replacement].

OBJECTIVE: To evaluate the results of reinfusion of autologous shed blood after joint replacement. METHODS: From February 1996 to March 1998, we selected 36 patients for 56 joint replacements. Apart from preoperative donation of autologous blood, all patients received transfusion of unwashed autologous drained blood from hips and knees after arthroplasty. The CBCIIConstaVac blood conservation system was used to salvage shed blood. Among the patients, 8 hips and 48 knees were involved. 12 patients had rheumatoid arthritis, 16 osteoarthritis, 5 ankylosing spondylitis, and 3 other arthritis. RESULTS: 36 patients received 24 260 ml (50%) autologous shed blood, 9 700 ml (20%) reserved autologous blood, and 14 600 ml (30%) allogenic blood. 15 patients experienced transient febrile reaction at the time of reinfusion, no other clinic abnormalities were discovered after reinfusion. CONCLUSIONS: Reinfusion of autologous shed blood is a safe and effective to decrease the use of allogenic blood and avoid the complications of its transfusion.

Adult↗
PubMed1999

[Cardiac metal foreign body: analysis of 21 cases].

OBJECTIVE: To improve early diagnosis and clinical treatment of metal foreign body in the heart. METHODS: In 21 patients, case history, clinical manifestation, chest X-ray film, and echocardiograph were reviewed. 20 patients received operation: emergency exploration (13) and elective operation (7). Four patients were subjected to cardiopulmonary bypass. The other one was not operated on because of absence of symptoms and small foreign body. Foreign bodies mostly bullets, were usually located in the right ventricle. Ventricular fibrillation occurred in 3 patients during operation, two of them were resuscitated. RESULTS: 20 patients but one recovered, a mortality rate of 5%. CONCLUSIONS: Early diagnosis, rapid management, and localization of foreign body are essential to the selection of treatment.

Adolescent↗
PubMed1999

[Characteristics of pulmonary function changes in cough variant asthma and chronic asthmatic bronchitis].

To understand with greater clearness the characteristics of pulmonary function changes in patients with cough variant asthma (CVA) and patients with chronic asthmatic bronchitis(CAB), 30 cases of CVA and 25 cases of CAB were examined by pulmonary function test and were compared clinically. The results showed the differences in medical history and some clinical manifestations between the two groups were significant (P < 0.05). The expiratory flow parameters (PEF, MMEF, FEV1) of pulmonary function test in CVA were generally normal; these parameters in CAB group, however, were obviously decreased. The airway challenge test uncovered a 100% positive reaction in CVA patients, but only less than 1/4 of the patients with CAB showed positive reaction. Furthermore, the positive concentration of challenge agents (Mch) required for CVA group was 1/4.7 of the ones for CAB group, and the positive Mch concentrations of the two groups seldom crossed each other. It is concluded that some clinical manifestations of CVA and CAB were significantly different, although many similarities between them do exist; the MEFV curve in pulmonary function test and the airway challenge test can be used to differentiate them well.

Adult↗
PubMed1999

[Ectopic meningiomas of the head and neck (report of 10 cases)].

OBJECTIVE: To study the diagnosis and treatment of ectopic meningiomas of the head and neck. METHOD: A retrospective review was made of 10 patients with ectopic meningiomas of the head and neck, the pathological diagnosis was as follows: 2 case epithelial type, 2 case psammomatous type, 1 case transitional type, 1 case malignant meningioma and types of another 4 cases were unknown. RESULT: All patients were treated surgically, 4 patients with local recurrence were operated secondarily and no signs were observed with the follow-up of many years. CONCLUSION: Surgery was the choice of ectopic meningiomas of the head and neck.

Adolescent↗
PubMed1999

[Chemical constituents of Girardinia palmata ssp ciliata].

Thirteen constituents were identified from Girardinia palmata ssp ciliata C. J. Chen by using GC-MS, which amounted to 84.5% of the total peaks, the main constituent were linoleic acid (52.01%) and dimethyl fumarate (10.05%). The dissociated amino acids and KNO(3) in the sample amounted to 43.30 mg/100 g and 3.0%. Five compounds were isolated and elucidated as octadecane, hexadecylic acid, beta-sitosterol, p-coumaric acid and potasium nitrate.

Alkanes↗
PubMed1998

Predicting function: from genes to genomes and back.

Predicting function from sequence using computational tools is a highly complicated procedure that is generally done for each gene individually. This review focuses on the added value that is provided by completely sequenced genomes in function prediction. Various levels of sequence annotation and function prediction are discussed, ranging from genomic sequence to that of complex cellular processes. Protein function is currently best described in the context of molecular interactions. In the near future it will be possible to predict protein function in the context of higher order processes such as the regulation of gene expression, metabolic pathways and signalling cascades. The analysis of such higher levels of function description uses, besides the information from completely sequenced genomes, also the additional information from proteomics and expression data. The final goal will be to elucidate the mapping between genotype and phenotype.

Bacterial Proteins↗
PubMed1998

A viral gene that activates lytic cycle expression of Kaposi's sarcoma-associated herpesvirus.

Herpesviruses exist in two states, latency and a lytic productive cycle. Here we identify an immediate-early gene encoded by Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus eight (HHV8) that activates lytic cycle gene expression from the latent viral genome. The gene is a homologue of Rta, a transcriptional activator encoded by Epstein-Barr virus (EBV). KSHV/Rta activated KSHV early lytic genes, including virus-encoded interleukin 6 and polyadenylated nuclear RNA, and a late gene, small viral capsid antigen. In cells dually infected with Epstein-Barr virus and KSHV, each Rta activated only autologous lytic cycle genes. Expression of viral cytokines under control of the KSHV/Rta gene is likely to contribute to the pathogenesis of KSHV-associated diseases.

Amino Acid Sequence↗
PubMed1998

The biosynthesis of mycolic acids in Mycobacterium tuberculosis. Enzymatic methyl(ene) transfer to acyl carrier protein bound meromycolic acid in vitro.

A closely related family of enzymes from Mycobacterium tuberculosis has been shown by heterologous expression to catalyze the modification of mycolic acids through the addition of a methyl (or methylene) group derived from S-adenosyl-L-methionine (SAM). Overproduction of all six of these enzymes in Escherichia coli and subsequent in vitro reactions with heat-inactivated acceptor fractions derived from Mycobacterium smegmatis in the presence of [methyl-3H]SAM demonstrated that the immediate substrate to which methyl group addition occurs was a family of very long-chain fatty acids. Inhibitors of methyl transfer, such as S-adenosyl-L-homocysteine and sinefungin, were shown to inhibit this reaction but had no effect on whole cells of either M. smegmatis or M. tuberculosis. Purified mycolic acids from M. tuberculosis were pyrolyzed, and the resulting meroaldehyde was oxidized and methylated to produce full-length methyl meromycolates. These esters were shown to comigrate with a fraction of the acceptor from the in vitro reactions, suggesting that methyl group addition occurs up to the level of the meromycolate. Protease and other treatments destroyed the activity of the acceptor fraction, which was also found to be extremely sensitive to basic pH. Antibody to the acyl carrier protein AcpM, which has recently been shown to be the carrier of full-length meromycolate produced by a unique type II fatty acid synthase system, inhibited the cell-free methyl(en)ation of these acids. These results suggest that mycolate modification reactions occur parallel with the synthesis of the AcpM-bound meromycolate chain.

Acyl Carrier Protein↗
PubMed1998

Reversed-phase high-performance liquid chromatography of virus-like particles.

A quantitative reversed-phase high-performance liquid chromatography (RP-HPLC) method has been developed to detect the L1 subunit protein from virus-like particles (VLPs) of human papillomavirus (HPV). The method utilizes heat treatment with a buffer consisting of 50 mM Tris, pH 8.0 containing 8 M guanidine-HCl and 10% 2-mercaptoethanol to dissociate the VLPs into monomeric L1. Following dissociation, the sample is injected onto a C4 or C8 column. The L1 protein is eluted as a single, clearly resolved peak. Elution conditions have been optimized to enhance the separation of L1 from other contaminants. Based on spike recovery studies and sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis this method is suitable for quantitation of various partially purified in-process samples and can be used to facilitate purification process development.

Blotting, Western↗
PubMed1998

PIR1, a novel phosphatase that exhibits high affinity to RNA . ribonucleoprotein complexes.

Protein tyrosine phosphatases are involved in the regulation of important cellular processes such as signal transduction, cell cycle progression, and tumor suppression. Here we report the cloning and characterization of PIR1, a novel member in the dual-specificity phosphatase subfamily of the protein tyrosine phosphatases. PIR1 also contains two stretches of arginine-rich sequences. We have shown that the recombinant PIR1 protein possessed an intrinsic phosphatase activity on phosphotyrosine-containing substrate. A unique feature of this phosphatase is that it binds directly to RNA in vitro with high affinity. In addition, we have found that PIR1 interacted with splicing factors 9G8 and SRp30C, possibly through an RNA intermediate during a yeast two-hybrid screen. PIR1 exhibited a nuclear-staining pattern that was sensitive to RNase A, but not to DNase I, suggesting that PIR1 in the cells are associated with RNA and/or ribonucleoprotein particles. Furthermore, a fraction of PIR1 showed a speckle-staining pattern that superimposed with that of the splicing factor, SC35. Taken together, our data suggest that PIR1 is a novel phosphatase that may participate in nuclear mRNA metabolism.

Amino Acid Sequence↗
PubMed1998

The 16-kDa alpha-crystallin (Acr) protein of Mycobacterium tuberculosis is required for growth in macrophages.

Although the 16-kDa alpha-crystallin homologue of Mycobacterium tuberculosis (MTB) is the dominant protein produced by stationary phase cultures in vitro, it is undetectable in logarithmically growing cultures. By growing bacilli at defined oxygen concentrations, acr transcription was shown to be strongly induced by mildly hypoxic conditions. Acr expression also was found to be induced during the course of in vitro infection of macrophages. The acr gene was replaced with a hygromycin resistance cassette by allelic exchange in MTB H37Rv. The resulting Deltaacr::hpt strain was shown to be equivalent to wild-type H37Rv in in vitro growth rate and infectivity but was significantly impaired for growth in both mouse bone marrow derived macrophages and THP-1 cells. In addition to its proposed role in maintenance of long-term viability during latent, asymptomatic infections, these results establish a role for the Acr protein in replication during initial MTB infection.

Animals↗
PubMed1998

Homology-based fold predictions for Mycoplasma genitalium proteins.

Homology search techniques based on the iterative PSI-BLAST method in combination with various filters for low sequence complexity are applied to assign folds to all Mycoplasma genitalium proteins. The resulting procedure (implemented as a web server) is able to predict at least one domain in 37% of these proteins automatically, with an estimated accuracy higher than 98%. Taking structural features such as coiled coil or transmembrane regions aside, folds can be assigned to more than half of the globular proteins in a bacterium just by iterative sequence comparison.

Bacterial Proteins↗
PubMed1998

Germline mutations of hMLH1 and hMSH2 genes in patients with suspected hereditary nonpolyposis colorectal cancer and sporadic early-onset colorectal cancer.

PURPOSE: The present study was designed to determine the frequency of germline mutations in the hMLH1 and hMSH2 genes in 31 families suspected of having hereditary nonpolyposis colorectal cancer who do not fulfill the criteria of the International Collaborative Group on Hereditary Nonpolyposis Colorectal Cancer but in whom a genetic basis for colon cancer is strongly suspected and 45 patients with sporadic early-onset colorectal cancer who developed colorectal cancer before the age of 40 years without any family history of colorectal cancer. METHODS: Genomic DNAs were prepared from peripheral blood samples of patients who were tested. All coding exons and exon-intron borders of these two genes were screened, first with the polymerase chain reaction-single-strand conformation polymorphism method, followed by sequencing of the DNA fragments displaying an abnormal single-strand conformation polymorphism pattern. RESULTS: In 31 families with suspected hereditary nonpolyposis colorectal cancer, we found six different germline mutations in seven unrelated families, including one missense mutation and three frame-shift mutations in the hMLH1 gene and one missense mutation and one frame-shift mutation in the hMSH2 gene. Totally, frequency of mutation was 23 percent, 16 percent and 7 percent in the hMLH1 and hMSH2, respectively. Only one missense mutation of the hMSH2 gene was identified in 45 patients (2 percent) with sporadic early-onset colorectal cancer. The mutation detection rate in families with suspected hereditary nonpolyposis colorectal cancer was significantly higher than that of patients with sporadic early-onset colorectal cancer (P < 0.05). CONCLUSION: Our definition of suspected hereditary nonpolyposis colorectal cancer is useful in the diagnosis of hereditary nonpolyposis colorectal cancer and for identifying those families who need genetic presymptomatic diagnosis. Our results indicate that it may be important to perform DNA testing in families suspected of having hereditary nonpolyposis colorectal cancer. On the other hand, we only detected a low mutation rate (2 percent) in 45 patients with sporadic early-onset colorectal cancer.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Study on amino acid composition of HSP70 and the level of plasma free amino acids of workers with long-term exposure to harmful factors.

In order to know the practical value of heat stress protein 70 (HSP70) and to know the changes of plasma free amino acids of workers with the induction of HSP70 by harmful factors, the amino acid composition of major HSP, HSP70 purified from the heated cultured human leukemia cancer cell line K562, rabbit liver, rat liver and heart, and mouse liver with two-step procedures of DE52-cellulose ion exchange chromatography and affinity chromatography on ATP-agarose was examined. The level of plasma free amino acids of workers with long-term exposure to heat, carbon monoxide and the combined effect of both heat and carbon monoxide was also investigated. The results showed that the three richest amino acids in HSP70 of all origins were Gly, Glu and Asp, except that of rat heart which was rich in Gly, Phe and Glu. Additionally, Lys, Val, Leu and Ala were also found very rich in HSP70 of all origins. Compared with controls, the most of plasma free amino acids tended to increase and free methionine and tryptophan were increased significantly (P < 0.05) after a long-term exposure to heat, carbon monoxide, and both. These findings suggested that further studies need to be done to find the substances or drugs which induce the synthesis of HSP70 and reduce the inhibition of synthesis of normal proteins for the purpose of protecting people with exposure to harmful factors against the damage of the factors.

Amino Acids↗
PubMed1998

Disposal options and case-study pathway analyses.

This paper presents an overview of alternatives that currently are employed for the disposal of wastes containing enhanced concentrations of naturally occurring radioactive materials (NORM). The application of pathway assessment methodology to the derivation of acceptable cleanup criteria for residual NORM is described. A specific example is provided drawing on experience with a site containing above-background levels of natural uranium-series and thorium-series nuclides. The options for safe, permanent disposal of U and Th bearing NORM waste are discussed and the application of pathway analysis to performance assessment of a typical engineered disposal cell is illustrated. Typical methods for disposal of other NORM waste forms also are described. This includes radium-contaminated wastes from petroleum sludges, uranium milling, and geothermal power plant operation as well as thorium wastes from production of thorium-magnesium alloys.

Background Radiation↗
PubMed1998

Inhibition of viral gene expression by human ribonuclease P.

External guide sequences (EGSs) are small RNA molecules which consist of a sequence complementary to a target mRNA and render the target RNA susceptible to degradation by ribonuclease P (RNase P). EGSs were designed to target the mRNA encoding thymidine kinase (TK) of herpes simplex virus 1 for degradation. These EGSs were shown to be able to direct human RNase P to cleave the TK mRNA sequence efficiently in vitro. A reduction of about 80% in the expression level of both TK mRNA and protein was observed in human cells that steadily expressed an EGS, but not in cells that either did not express the EGS or produced a "disabled" EGS which carried a single nucleotide mutation that precluded RNase P recognition. Thus, EGSs may represent novel gene-targeting agents for inhibition of gene expression and antiviral activity.

Animals↗