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Biomedical subjects

X Ma

Publications and source records attributed to X Ma.

At least 217 records · Page 12Linked to original sources
PubMed1998

The use of a chimera HIV-1/HIV-2 envelope protein for immunodiagnosis of HIV infection: its expression and purification in E. coli by use of a translation initiation site within HIV-1 env gene.

A chimera HIV-1/HIV-2 envelope sequence composed of multiple conserved immunodominant epitopes of HIV-1 envelope protein (HIV-1 IIIB: env482-518 + env548-675) and the HIV-2 gp36 immunodominant epitope (env592-603), was constructed and directly over-expressed in E. coli by using a prokaryotic translation initiation sequence contained within the gene of HIV-1 envelope. The recombinant product was purified and applied in antibody-screening assay. The purified chimera antigen reacted with all the thirty-eight HIV-1 positive serum samples, the two HIV-2 serum samples, and had no cross-reaction with all the eighty-eight normal healthy serum sample. The results indicated that this recombinant chimera HIV-1/HIV-2 envelope protein could be useful for diagnostic purposes of HIV infection.

AIDS Serodiagnosis↗
PubMed1998

Evidence of nosocomial infection in Japan caused by high-level gentamicin-resistant Enterococcus faecalis and identification of the pheromone-responsive conjugative plasmid encoding gentamicin resistance.

A total of 1,799 Enterococcus faecalis isolates were isolated from inpatients of Gunma University Hospital, Gunma, Japan, between 1992 and 1996. Four hundred thirty-two (22.3%) of the 1,799 isolates had high-level gentamicin resistance. Eighty-one of the 432 isolates were classified and were placed into four groups (group A through group D) with respect to the EcoRI restriction endonuclease profiles of the plasmid DNAs isolated from these strains. The 81 isolates were isolated from 36 patients. For 35 of the 36 patients, the same gentamicin-resistant isolates were isolated from the same or different specimens isolated from the same patient at different times during the hospitalization. For one other patient, two different groups of the isolates were isolated from the same specimen. Groups A, B, C, and D were isolated from 5, 14, 12, and 6 patients, respectively. The strains had multiple-drug resistance. The restriction endonuclease digestion patterns of the E. faecalis chromosomal DNAs isolated from isolates in the same group were also identical. The patients who had been infected with the gentamicin-resistant isolates from each group were geographically clustered on a ward(s). These results suggest that the isolates in each group were derived from a common source and had spread in the ward. The gentamicin-resistant isolates exhibited a clumping response upon exposure to pheromone (E. faecalis FA2-2 culture filtrate). The gentamicin resistance transferred at a high frequency to the recipient E. faecalis isolates by broth mating, and the pheromone-responsive plasmids encoding the gentamicin resistance were identified in these isolates.

Conjugation, Genetic↗
PubMed1998

Serum deprivation induces a unique hypercontractile phenotype of cultured smooth muscle cells.

Chronic asthma is characterized by hypertrophy and hyperplasia of airway smooth muscle cells (SMC) that limit airflow by a geometric effect. Whether contractility of airway SMC is altered is not clear. Cultured cells were used as a model of hyperplasia. Phenotypic changes seen indicated conversion to a synthetic, weakly contractile type. At confluence, although limited reversal of protein changes was seen, no restoration in contractility occurred. Phenotypic modulation of postconfluent cultured airway SMC under prolonged serum deprivation (arrested cells) is reported here. Two phenotypically distinct groups of cells were identified in primary airway SMC cultures: 1) elongated spindle-shaped cells, which expressed large amounts of smooth muscle contractile and regulatory proteins, and 2) flat and stellate cells, which expressed very little. The first group showed a surprising shortening capacity and a velocity that was even greater than that of the freshly isolated cells, whereas the second group became spherical and noncontractile. Even more surprising was that the myosin heavy chain (MHC) isoform (SM-B) generally said to be associated with the higher shortening velocity disappeared from the cell, while the content of the key rate-limiting regulating enzyme, myosin light chain kinase (MLCK), increased 30-fold. We conclude that a functional, contractile phenotype of airway SMC can be obtained by prolonged serum deprivation. We speculate that the increased contractility could be the result of increased phosphorylation of the 20-kDa myosin light chain resulting from increased content of smooth muscle MLCK rather than any increase in endogenous MHC ATPase activity. This model may be useful for study of SMC differentiation and contraction.

Actins↗
PubMed1998

The contractile apparatus of airway smooth muscle. Biophysics and biochemistry.

Qualitatively the mechanical, structural, and biochemical properties of airway smooth muscles resemble those of all other smooth muscle. However, one important distinguishing feature of airway smooth muscle is that the major portion of isotonic shortening is completed within the first 3 s in a muscle whose contraction is 10 s. This indicates the importance of focusing on the changes that occur in these 3 s and also the limiting role of the maximum velocity of shortening in determining shortening data. There is evidence that the maximum capacity and velocity of shortening in human bronchial smooth muscle from patients with asthma are significantly greater than those obtained from healthy siblings. In the demonstration in which cells in culture are arrested by withdrawing all fetal calf serum, the cells alter their phenotype to cells that are very long (more than 200 micrometers) and shorten twice as much as cells freshly isolated when the tissue is new. Speculatively, if such cells developed in vivo they could account for the increased contractility of asthmatic airway smooth muscle. These cultured cells could also be excellent models for study of airway smooth muscle contractility.

Animals↗
PubMed1998

Enhanced gene transfer into HuH-7 cells and primary rat hepatocytes using targeted liposomes and polyethylenimine.

Different ratios of DNA phosphate to polyethylenimine amine were used for encapsulation and delivery to liver cells of chloramphenicol acetyl transferase (CAT) or luciferase expression plasmids in cationic, neutral and anionic liposomes. Positive liposomes consisted of dioleoyl phosphatidylcholine (DOPC): dioleoyl trimethylammonium propane (DOTAP) (6:1 molar ratio); neutral liposomes were composed of DOPC and dioleoyl phosphatidylethanolamine (DOPE) (1:1); and negative liposomes contained dioleoyl phosphatidylserine (DOPS) and DOPC (1:1). All formulations included 8 mol% galatocerebroside for targeting to the hepatocyte asialoglycoprotein receptor. Liposomes were prepared by film hydration followed by sequential extrusion through 0.8-0.2 mumol polycarbonate membranes. Transfection efficiency of HuH-7 human hepatoma cells and isolated rat hepatocytes was determined by CAT enzyme-linked immunosorbent assay (ELISA) or luciferase activity. Uptake of liposomal-encapsulated, fluorescently labeled 68-mer oligonucleotides was assessed by confocal microscopy. All three formulations demonstrated a twofold or greater increase in transfection efficiency and significantly lower toxicity compared to nonencapsulated polyethylenimine complexes. Negative liposomes were most effective, particularly in the rat hepatocytes. Only the cationic and anionic liposomal formulations exhibited significant thermodynamic stability. These formulations are readily characterized for size, phospholipid and DNA content, and they represent feasible systems for optimizing in vivo delivery systems to hepatocytes.

Animals↗
PubMed1998

Changes of activity of liver glycogen synthase in experimental diabetes mellitus rats.

OBJECTIVE: To study the activity of liver glycogen synthase in analogous model of NIDDM rats. METHODS: Male Wistar rats were injected with low dose of streptozotocin (STZ) (30 mg/kg body weight) via tail vena and those animals with glucose tolerance impaired and level of insulin equal to or higher than that of the controls at 18th week were taken as the analogous rat model of NIDDM. The activity of liver glycogen synthase (GS) was assayed at the end of experiment. RESULTS: Type I-enzyme: 0.18 +/- 0.06 mumol/min.g versus 0.24 +/- 0.09 mumol/min.g, P < 0.05, and total-enzyme: 1.52 +/- 0.43 mumol/min. g versus 1.84 +/- 0.42 mumol/min.g, P < 0.05. CONCLUSION: The GS activity of diabetic rats was significantly lower than that of control.

Animals↗
PubMed1998

[Investigation of an Legionnaires' disease outbreak associated with contaminated air-conditioning].

An outbreak of upper respiratory infection (influenza-like syndrome) took place among the staff members of a large office building in Beijing, June, 1997. To understand the cause of the outbreak, with a case-control study with serological antibodies detection against serogroup 1 to 14 of Legionnaires' disease bacteria (LDB) and bacteriological test and culture on samples collected from the air-conditioning system of the office building was performed. The findings showed that the attack rates of tonsillitis and upper respiratory infection were 61.86% and 34.62% respectively. The relation was statistically significant between the symptoms of fever and tonsillitis in the cases (chi 2 = 77.88, P < 0.01). The positive rates of LDB antibodies on serogroups 9, 10, 12, 14 were 45.94% in the cases of upper respiratory infection and 3/15, 6/17, 0/15, 1/16 respectively in the four controls groups. Condensied water samples from an air-conditioning system showed that Legionella Pneumophila was positive. Evidence showed that it was an outbreak resulting from LDB serogroup 9 and 12, accompanied by upper respiratory infection related to air-conditioning system contaminated by LDB. This was the first report Lp infection associated with an air-conditioning system in China.

Air Conditioning↗
PubMed1998

Terminology and diagnostic classification of temporomandibular joint dysfunction syndrome in China.

OBJECTIVE: To advance a modified TMD classification suitable to dental practice in China. METHODS: A modified classification scheme was proposed based on reviews of the previous classification of TMD suggested by the authors and the classification schemes recommended by the International Headache Society (IHS), the American Academy of Orofacial Pain (AAOP), and other researchers. RESULTS: The following modified classification of TMD was suggested: I. Masticatory muscular disorders, including myofascial pain, myositis, myospasm, unclassified local muscular pain, and fibrostic contracture; II. Structural derangement disorders (or internal derangement disorders), including anterior disc displacement with or without reduction as well as other forms of disc displacement such as medial, lateral, and rotatory disc displacement; III. Inflammatory disorders, including acute and chronic synovitis and capsulitis; IV. Osteoarthrosis, including primary and secondary osteoarthrosis. CONCLUSIONS: The modified classification of TMD should simplify and improve the diagnosis and treatment of TMD in China. However, more is required to improve the general level of dental care in China and to overcome the shortcomings of the modified classification with regard to understanding the psychological effects of TMD and the use of advanced diagnostic techniques.

China↗
PubMed1998

[A comparison of chromosome fragile sites in elderly and young people].

In this comparative study, the authors investigated the chromosome aberrations and expression of fragile sites in the lymphocytes which were collected from 45 elderly people and 29 young people and were cultured with FUDR for 24 hours. The results showed that the aberration rate was 24.75% for elderly people, but 4.22% for young people (P < 0.01): that the expression of fragile sites was 45.94% for elderly peoples, but 23.02% for young people (P < 0.01): and that the relation of aberrations with fragile sites was 79.98% for elderly people, and 92% for young people. These findings suggest that chromosome aberration is in close association with fragile site.

Adolescent↗
PubMed1998

[Glucose-6-phosphate dehydrogenase mutations among Cantonese revealed by polymerase chain reaction using dried blood spots].

OBJECTIVE: To analyze G6PD gene mutation in 168 Cantonese G6PD deficient male infants. METHODS: PCR products were amplified directly from dried blood spots on filter paper using 7 pairs of special primers followed by digestion with a restriction enzyme. RESULTS: Of the 168 samples, 72(42.8%) were G6PD 1376 G-->T mutation, 35 (20.8%) were G6PD 1388 G-->A, 30(17.9%) were G6PD 95 AG, 6(3.6%) were G6PD 392 G-->T, and 3(1.8%) were G6PD 1024 C-->T. No G6PD 493 A-->G and 487 G-->A mutation were found, and 22(13.1%) were not defined. CONCLUSION: 1. The three G6PD mutations at 1376, 1388 and 95 were common in Cantonese. 2. Dried blood spots collected on filter paper provide an easy way of sample collection, storage and transport for the epidemiological study of inherited disease.

Adult↗
PubMed1998

[The relationship between HBV infection and injury of tubuli and interstitium in IgA nephropathy].

OBJECTIVE: To clarify the correlation between HBV infection and the injury of tubuli and interstitium of IgA nephropathy. METHODS: Renal biopsy specimens from 91 patients with primary IgA nephropathy were investigated by use of in situ hybridization (HBV DNA), immunohistochemistry (HBsAg, HBcAg, CD3, CD8) and HBV DNA, HBAg-CD43 double staining techniques. RESULTS: The positive rate of HBAg in renal tissue as detected by immunohistochemistry was 69.2% and that of HBV DNA detected by in situ hybridization was 42.9%. Double staining showed that HBV DNA positive tubular epithelial cells might coexpress HBsAg and/or HBcAg. The numbers of the infiltrated CD3+ cells and CD8+ cells in cases with positive HBV infections markers were significantly higher than those of cases without infection (P < 0.01). In addition, CD43+ T lymphocytes infiltrated around or invaded into the tubuli walls which had positive HBcAg or HBsAg expression. CONCLUSION: After HBV infection, the renal cells could express HBAg and induce infiltration of CD3+ cells and CD8+ cells, resulting in aggravation of the injury of tubuli and interstitium. Therefore, it is considered that HBV infection might play an important role in the occurrence and progress of IgA nephropathy.

Adult↗
PubMed1998

[Interleukin-6 gene cloning, expression and purification].

OBJECTIVE: The main purpose of this paper is to study the batch production of recombinant human interleukin-6(rhIL-6). METHODS: The cloned rhIL-6 gene is under the control of T7 promoter of pET30a vector and expressed in E. coli. RESULTS: The ratio of expressed recombinant protein to total cell protein is more than 50%. The rhIL-6 molecular weight is 21,000, isoelectric point is 6.7. The purity of the rhIL-6 is more than 95%, and the activity of rhIL-6, determined by IL-6 dependent mice hybridoma cell line 7TD1 and MTT assay, is 0.35 ng/ml. CONCLUSIONS: All results mentioned show that rhIL-6 meets the request of the middle scale production.

Cloning, Molecular↗
PubMed1998

[Determination of acetylcholine and choline in microdialysates from rat brain by high performance liquid chromatography with electrochemical detection combined with a post-column immobilized enzyme reactor].

In the present work, acetylcholine(ACh) and choline(Ch) in the microdialysates from three brain areas of anesthetized rats and from hippocampus and frontal cortex of freely moving rats were simultaneously measured by high performance liquid chromatography(HPLC) with electrochemical detection combined with a post-column immobilized enzyme reactor(IMER). This assay was based on the separation of ACh and Ch on a polymer gel column followed by passage of the effluent through an IMER, on which the separated ACh and Ch reacted respectively to give each stoichiometric yield of hydrogen peroxide, which was detected electrochemically at a platinum electrode (potential + 0.5 V versus Ag/AgCl). The tip of concentric dialysis probe was made of the semipermeable dialysis membrane of 0.22 mm in outside diameter, and the effective length inserted into rat brain was 3.0 mm. The probe was perfused at a rate of 1 microL/min with Ringer's solution which contained 10 mumol/L (for anesthetized rats) or 1 mumol/L (for freely moving rats) neostigmine, a reversible cholinesterase inhibitor, to elevate ACh level in microdialysate. Before the experiment, the recovery of the probe in vitro was measured at room temperature, and the position of the probe was checked by histological procedure at the end of the experiment. In the range of 0.2-100 mumol/L, the relation between the amounts and the peak areas was linear (r = 0.9988 for ACh and r = 0.9985 for Ch). The detection limit for ACh and Ch, at a S/N ratio of two, was found to be 50 fmol per injection. The probe recoveries(%) for ACh and for Ch were 23.2 +/- 1.4 and 34.3 +/- 3.2(mean +/- SD) respectively. The basal levels of ACh in the microdialysates from striatum and frontal cortex of anesthetized rats as well as from hippocampus and frontal cortex of freely moving rats were 212 +/- 28 and 22 +/- 4 as well as 26 +/- 4 and 83 +/- 7(nmol/L, mean +/- SD, not corrected according to probe recovery) respectively. The perfusion of high concentration K+ (100 mmol/L) through the dialysis probe induced a large increase of ACh in the microdialysates. The critical points for HPLC analysis combined with IMER were briefly discussed.

Acetylcholine↗
PubMed1998

[Diterpenoid alkaloids from Aconitum bulleyanum Diels].

OBJECTIVE: To investigate the diterpenoid alkaloids from Aconitum bulleyanum. METHOD: Diterpenoid alkaloids were separated by solvent extraction and chromatography on silical gel, and their structures were determined by spectral analysis and chemical evidence. RESULT: Five diterpenoid alkaloids were elucidated as yunaconitine, crassicauline A, vilmorrianine C, lycoctonine and lappaconitine. CONCLUSION: All the compounds were isolated from this plant for the first time.

Aconitine↗
PubMed1998

[Effect of different nitrogen concentrations on the growth and contents of berberine in rhizome of Coptis chinensis Franch].

OBJECTIVE: Selecting the best N concentrations for the growth of the Chinese goldthread(Coptis chinensis). METHOD: Employing sand culture procedures. RESULT: The symptoms of shortage of nitrogen were reduced in low N(1/5 N) solution, but the new roots and aerial parts were adversely affected in over nitrogen solution(2 N); the activity of NR in leaves and the content of berberine in rhizome were also low in 2 N solution; the range of optimum N concentrations for growth and high contents of effective components is 1/2 N to 1 N. CONCLUSION: The consumption of nitrogen by Coptis chinensis is lower in the period of maximum contents of effective components in rhizome than in the period of luxuriant growing of the plant.

Berberine↗
PubMed1998

[The effect of the macrophages conditioned media(MOCM) on NGF secretion in newborn rat schwann cells in vitro].

OBJECTIVE: To study the influence of macrophages on nerve growth factor (NGF) secretion in newborn rat schwann cells. METHODS: LPS-activated and not-activated adult rat peritoneal macrophages conditioned media (MOCM) were treated on purified cultured Schwann cells for 24, 48 and 72 hours in three different concentrations the NGF contents in the cultured Schwann cells suspension media were measured by a two-site enzyme-linked immunoserbent assay. RESULTS: Both L-MOCM (LPS-activated MOCM) and N-MOCM(not-activated MOCM) obviously enhanced NGF secretion in chwann cells in each different concentration or testing time. CONCLUSION: MOCM contains some factors which can promote NGF secretion in rat schwann cells in vitro, suggesting that macrophages regulating NGF secretion by secreted certain cytokines.

Animals↗
PubMed1998

[Influence of interleukin-1 and dexamethasone on prostaglandin production of condylar chondrocytes].

OBJECTIVE: To study the effect of recombinant human interleukin-1(rhIL-1) and dexamethasone on the amount of 6-keto-prostaglandin F1 alpha produced by condylar chondrocytes. METHODS: The concentration of 6-keto-prostaglandin F1 alpha of the chondrocytes supernate was detected respectively at 4, 8, 12, 24, and 72 hours, using the method of radioimmunoassay, after being stimulated by rhIL-1 and dexamethasone for four hours. RESULTS: In normal control group, the concentration of 6-keto-prostaglandin F1 alpha was 1,516.49 ng/L, 1,513.22 ng/L, 1,506.76 ng/L, 1,526.79 ng/L and 2,114.36 ng/L at 4, 8, 12, 24 and 72 hours respectively. In rhIL-1 group, the concentration of 6-keto-prostaglandin F1 alpha was 1,664.32 ng/L at four hours, which was sharply higher than that of the control group(P < 0.01); the concentration of 6-keto-prostaglandin F1 alpha was 1,146.11 ng/L, 949.24 ng/L, 1,392.33 ng/L and 1,481.98 ng/L at 8, 12, 24 and 72 hours respectively, which were sharply lower than that of the control group(P < 0.01). After the condylar chondrocytes were stimulated with dexamethasone for 4 hours, the concentration of 6-keto-prostaglandin F1 alpha decreased more markedly than that of the control group(P < 0.01) throughout the observation period, both in the presence and absence of rhIL-1. CONCLUSION: rhIL-1 could enhance the production of 6-keto-prostaglandin F1 alpha synthesized by condylar chondrocytes. Dexamethasone could inhibit the activity of rhL-1 and the production of 6-keto-prostaglandin F1 alpha synthesized by condylar chondrocytes.

6-Ketoprostaglandin F1 alpha↗