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Biomedical subjects

J Xue

Publications and source records attributed to J Xue.

At least 91 records · Page 5Linked to original sources
PubMed1996

Molecular cloning and mRNA tissue distribution of a novel matrix metalloproteinase isolated from porcine enamel organ.

A cDNA encoding a novel matrix metalloproteinase (MMP) was isolated from a porcine enamel organ-specific cDNA library. Multiple tissue northern blot analysis revealed the presence of two mRNA transcripts which were expressed only in the enamel organ. The transcripts were 1968 bp or 3420 bp in length and resulted from the utilization of alternative polyadenylation sites. The open reading frame of the cloned mRNA encodes a protein composed of 483 amino acids. The MMP has a predicted molecular mass of 54.1 kDa, which is similar to that of the stromelysins or collagenases, although it is not a member of either of these two classes of MMPs. A motif analysis revealed that the cloned MMP does not contain a consensus hemopexin-like domain because it lacks a critical tryptophan and proline residue at the appropriate positions. Since the cloned MMP is a new member of the MMP gene family and its expression appears limited to the enamel organ, we have named it enamelysin.

Amino Acid Sequence↗
PubMed1996

Particulate air pollution and respiratory disease in Anchorage, Alaska.

This paper examines the associations between average daily particulate matter less than 10 microns in diameter (PM10) and temperature with daily outpatient visits for respiratory disease including asthma, bronchitis, and upper respiratory illness in Anchorage, Alaska, where there are few industrial sources of air pollution. In Anchorage, PM10 is composed primarily of earth crustal material and volcanic ash. Carbon monoxide is measured only during the winter months. The number of outpatients visits for respiratory diagnoses during the period 1 May 1992 to 1 March 1994 were derived from medical insurance claims for state and municipal employees and their dependents covered by Aetna insurance. The data were filtered to reduce seasonal trends and serial autocorrelation and adjusted for day of the week. The results show that an increase of 10 micrograms/m3 in PM10 resulted in a 3-6% increase in visits for asthma and a 1-3% increase in visits for upper respiratory diseases. Winter CO concentrations were significantly associated with bronchitis and upper respiratory illness, but not with asthma. Winter CO was highly correlated with automobile exhaust emissions. These findings are consistent with the results of previous studies of particulate pollution in other urban areas and provide evidence that the coarse fraction of PM10 may affect the health of working people.

Air Pollutants↗
PubMed1996

Breed differences in boar taint: relationship between tissue levels boar taint compounds and sensory analysis of taint.

A total of 228 intact male pigs form Duroc, Hampshire, Landrace, and Yorkshire breeds were used in the experiment. Samples of salivary gland and backfat were collected at slaughter for colorimetric assay of salivary and fat 16-androstene levels and fat skatole levels. Fat levels also were tested by a sensory panel using an R-index technique for detecting the presence of boar taint. The proportion of tainted carcasses determined by the sensory panel was 5.0% for androstenone and 11.4% for skatole, with a combined total of 15.0% tainted from either source. Sensory analysis of taint showed a lower proportion (P < .05) of tainted carcasses in Hampshire, with no difference in taint across the other three breeds. Analysis of taint compounds indicated that overall 14.5% of pigs had salivary gland 16-androstene levels and 20.9% had fat 16-androstene levels above acceptable limits. There was a higher (P < .05) proportion of Duroc pigs above the threshold levels for 16-androstenes in both salivary gland and fat. Landrace pigs had the lowest (P < .05) average tissue concentrations of steroids and skatole. Across breeds, only 1.8% of pigs had fat skatole concentrations above .25 ppm, which has been suggested as threshold levels of skatole for taint. The canonical correlation coefficient between fat compound levels and the R-indices of fat 16-androstenes and skatole was .40 (P < .001). Our results indicate breed differences in tissue levels of taint compounds and in taint assessed by a sensory panel. Levels of 16-androstene steroids were highly associated with taint, but more pigs had measured levels above the threshold than those identified as tainted by sensory analysis. Levels of fat skatole were low overall and did not account for all the pigs judged as tainted from skatole by sensory analysis.

Androstenes↗
PubMed1996

[Transurethral noncontact laser ablation of the large prostate].

42 cases of the large benign hypertrophy of the prostate were treated by transurethral noncontact laser ablation. The results of the patients followed up no less than six months and treatment were reported. The technique of the procedure and its related problems were described and our experience was presented. If we use the technique of the procedure skill fully, noncontact laser ablation of large benign hypertrophy of the prostate is safe and effective.

Adolescent↗
PubMed1996

[Longitudinal evaluation of vocal function following thyroplasty type I for the treatment of unilateral vocal paralysis].

Longitudinal changes of vocal efficiency and stability following thyroplasty type I were analysed. Fifty-three patients with unilateral vocal fold paralysis underwent vocal function evaluation preoperatively and 1, 3 and 6 months postoperatively. Vocal function assessment included videostrobolaryngoscopic examination, acoustical and aerodynamic analyses, and perceptual ratings of voice. Parameters including glottic gag size, maximum phonation time, glottic flow rate, jitter, harmonic to noise ratio, breathness, hoarseness, loudness and phrasing showed significant improvement after thyroplasty and remained stable within 1 month with only slight fluctuations over a 6 month period. Postoperative voice outcome was not affected by age, sex, duration of vocal symptoms, etiology of paralysis, or preoperative pulmonary function.

Adolescent↗
PubMed1995

Determination of polyamines in serum by high-performance capillary zone electrophoresis with indirect ultraviolet detection.

A method for determining polyamines in serum by capillary zone electrophoresis (CZE) with indirect ultraviolet detection was established. The concentrations of polyamines in the sera of six healthy adults were determined and the results were in accordance with those obtained previously by high-performance liquid chromatography (HPLC). However, the CZE method is superior to HPLC in that it has high sensitivity, small sample consumption and easy sample pretreatment.

Adult↗
PubMed1995

Human thioredoxin reductase directly reduces lipid hydroperoxides by NADPH and selenocystine strongly stimulates the reaction via catalytically generated selenols.

Human placenta thioredoxin reductase (HP-TR) in the presence of NADPH-catalyzed reduction of (15S)-hydroperoxy-(5Z),(8Z),11(Z),13(E)-eicosatetraenoic acid ((15S)-HPETE) into the corresponding alcohol ((15S)-HETE). Incubation of 50 nM HP-TR and 0.5 mM NADPH with 300 microM 15-HPETE for 5 min resulted in formation of 16.5 microM 15-HETE. After 60 min, 74.7 microM 15-HPETE was reduced. The rate of the reduction of 15-HPETE by the HP-TR/NADPH peroxidase system was increased 8-fold by the presence of 2.5 microM selenocystine, a diselenide amino acid. In this case, 15-HPETE was catalytically reduced by the selenol amino acid, selenocysteine, generated from the diselenide by the HP-TR/NADPH system. To a smaller extent, selenodiglutathione or human thioredoxin also potentiated the reduction of 15-HPETE by HP-TR. Hydrogen peroxide and 15-HPETE were reduced at approximately the same rate by HP-TR, thioredoxin, and selenocystine. In contrast, t-butyl hydroperoxide was reduced at a 10-fold lower rate. Our data suggest two novel pathways for the reduction and detoxification of lipid hydroperoxides, hydrogen peroxide, and organic hydroperoxides, i.e. the human thioredoxin reductase-dependent pathway and a coupled reduction in the presence of selenols or selenide resulting from the reduction of selenocystine or selenodiglutathione.

Catalysis↗
PubMed1995

The unusual 5' splicing border GC is used in myrosinase genes of the Brassicaceae.

Myrosinase (thioglucosidase glucohydrolase; EC 3.2.3.1) is a group of isoenzymes in the Brassicaceae, which hydrolyze glucosinolates. Genes encoding myrosinase contain 12 exons and 11 introns. Sequence comparison of two myrosinase genes from Arabidopsis thaliana, TGG1 and TGG2, with the corresponding cDNA from leaves, showed preferential use of a GC dinucleotide as the 5' splicing border in intron 1 instead of an adjacent GT dinucleotide four bp further 3'. This 5' GC splice site is conserved in all seven myrosinase genes characterized from three different species. Likewise, in the 3' region of intron 1 two AG dinucleotides are located seven bp apart. Only the most 5' of these dinucleotides was found to be used in splicing. Sequence analyses of TGG1 cDNA isolated from seeds, siliques and vegetative tissue using reverse transcription PCR showed that the splicing pattern of this intron is identical in these tissues for TGG1. The GT and the most 3' AG dinucleotides mentioned above have been assumed to be the intron borders of intron 1 in several myrosinase genes. The present investigation shows that this assumption is not correct.

Amino Acid Sequence↗
PubMed1995

The myrosinase gene family in Arabidopsis thaliana: gene organization, expression and evolution.

Myrosinase (thioglucoside glucohydrolase, EC 3.2.3.1.) is in Brassicaceae species such as Brassica napus and Sinapis alba encoded by two differentially expressed gene families, MA and MB, consisting of about 4 and 10 genes, respectively. Southern blot analysis showed that Arabidopsis thaliana contains three myrosinase genes. These genes were isolated from a genomic library and two of them, TGG1 and TGG2, were sequenced. They were found to be located in an inverted mode with their 3' ends 4.4 kb apart. Their organization was highly conserved with 12 exons and 11 short introns. Comparison of nucleotide sequences of TGG1 and TGG2 exons revealed an overall 75% similarity. In contrast, the overall nucleotide sequence similarity in introns was only 42%. In intron 1 the unusual 5' splice border GC was used. Phylogenetic analyses using both distance matrix and parsimony programs suggested that the Arabidopsis genes could not be grouped with either MA or MB genes. Consequently, these two gene families arose only after Arabidopsis had diverged from the other Brassicaceae species. In situ hybridization experiments showed that TGG1 and TGG2 expressing cells are present in leaf, sepal, petal, and gynoecium. In developing seeds, a few cells reacting with the TGG1 probe, but not with the TGG2 probe, were found indicating a partly different expression of these genes.

Amino Acid Sequence↗
PubMed1995

[Effect of low dose rhTNF-alpha on immune function of lymphocytes in burned rats].

SD rats (200-230 g body weight) were randomly divided into three groups: (1) sham burn; (2) burn; (3) burn plus rhTNF-alpha. Third degree burn of 30% TBSA on the trunk was produced in groups 2 and 3. Intravenous rhTNF-alpha(10 micrograms/kg) was administered 6 hours postburn and once daily thereafter for 5 days in group 3. At 5 days postburn, splenic lymphocytes obtained from all the animals were used for the determination of distribution of T lymphocyte subsets with flowcytic analysis and activity of IL-2(Gills method). The results indicated that low dose rhTNF-alpha in vivo could improve distribution of splenic T lymphocyte subsets in burned rats by increasing the numbers of W3/25(Th) and decreasing the number of OX-8(Ts), and the ratio of W3/25/OX-8 was raised. In vitro the proliferation response of T lymphocytes to ConA was enhanced and the activity of IL-2 was increased by 108%, 149% and 168%, respectively, in group 3 compared with that in group 2. However, a dose-dependent effect, in that a small dose (< or = 10 ng/2.5 x 10(6) cells) of rhTNF-alpha improved the immune function of T lymphocytes, while a higher dose inhibited T lymphocyte immune function. These findings showed that rhTNF-alpha improved not only the distribution of T lymphocyte subsets but also their immune activity.

Animals↗
PubMed1995

Construction and high expression of retroviral vector with human clotting factor IX cDNA in vitro.

The construction of the high titer and highly expressed safety retroviral vector carrying human clotting factor IX cDNA is reported. Retroviral vectors LNCIX, LIXSN and LCIXSN, driven by hCMV, LTR and hCMV combined with LTR promoter respectively, were constructed, based on the retroviral vector LNL6, and transferred into packaging cell line PA317 with electroporation. Human clotting factor IX was detected in the cultured cells transduced with LNCIX and LIXSN but not in the cells transduced with LCIXSN. The viral titer of PA317/LNCIX was 800,000 CFU per mL. With ELISA detection, it was found that the cells transduced with this vector can express human clotting factor IX at the level of 3.3 micrograms per 10(6) cells in 24 h in human fibrosarcoma cells HT-1080 and 2.5 micrograms per 10(6) cells in 24 h in hemophilia B patients' skin fibroblast HSF cells, and more than 80% of them were biologically active. The viral titer and expression of human FIX were increased, and the construction of retroviral vector backbone was improved and the safety was guaranteed as compared to those vectors used previously. These vectors may produce a sufficient quantity of factor IX proteins to cause the phenotypic modification for hemophilia B patients.

Cells, Cultured↗
PubMed1995

Regulation of human clotting factor IX cDNA expression in transgenic mice.

To study the expression of human clotting factor IX cDNA in transgenic mice, which is an essential work on gene therapy for hemophilia B, 3 recombinant constructions containing different lengths of human clotting factor IX cDNA have been introduced into the cultured cells. All of the recombinant constructions were found to be expressed well in vitro. They were then microinjected into the male pronuclei of the fertilized mouse eggs respectively for generating transgenic mice. Unfortunately, none of them was expressed in any transgenic mice. These results show that the expression of the human clotting factor IX cDNA in the transgenic mice can be determined by cis regulatory element(s). As compared with the results from other related works, it is suggested that the cis regulatory element(s) is resided in the 5'-end non-coding region.

Animals↗
PubMed1995

Characterization of bronchodilator effects and fate of S-nitrosothiols in the isolated perfused and ventilated guinea pig lung.

In this study the effects of S-nitrosothiols, in particular S-nitrosoglutathione (GSNO), were evaluated with regard to their bronchodilating properties, both after infusion via the pulmonary circulation and after inhalation, in the isolated perfused and ventilated guinea pig lung. Infused GSNO induced bronchorelaxation of lungs that were precontracted with methacholine. During a 15-min period of single-passage perfusion with GSNO (10 microM), maximally 10% was taken up and/or degraded by the lung. A spontaneous breakdown of GSNO in the perfusion buffer was also observed, which was partially accompanied by the formation of nitrite. Low levels of nitric oxide (NO) were detected in the perfusion buffer when GSNO was present. This was due to the presence of contaminating transition metals, because EDTA and 2,2'-dipyridyl largely reduced the formation of NO. The NO-scavenging agents oxyhemoglobin and 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide abolished levels of NO in the buffer but did not abolish GSNO-induced bronchodilation. The effects of infused GSNO are therefore attributed to an action of the intact S-nitrosothiol and not to NO released from GSNO in the perfusion buffer. Similarly, perfusion with S-nitrosated glutathione isopropyl ester, cysteinyl glycine, N-acetyl-L-cysteine or N-acetyl-D,L-penicillamine, but not with nitrosated bovine serum albumin or sodium nitrite, was found to induce bronchodilation. Inhalation of nebulized GSNO induced bronchodilation of methacholine-precontracted lungs with a rapid onset of action, although it was a less potent bronchodilator than salbutamol. The results show that infused or inhaled S-nitrosothiols have bronchodilating properties in the isolated perfused and ventilated guinea pig lung.

Aerosols↗
PubMed1995

[Characterization of human coagulation factor IX cDNA expressed in cultured cells and in transgenic mice].

Two recombinant genes containing human coagulation factor IX cDNA driven by SV40 early promoter or by mouse MT promoter were introduced into the cultured mouse fabroblasts, respectively. It was found that both of them could be expressed in the cultured cells. Then, the two recombinant genes were microinjected into the male pronuclei of fertillized mouse eggs for generating transgenic mice harbouring the introduced genes, respectively. However, we did not observed that the two genes could be expressed in transgenic mice. These results suggest that the in vivo expression of human coagulation factor IX cDNA be controlled by some cis regulatory element (s).

Animals↗
PubMed1994

The thioredoxin and glutaredoxin systems are efficient electron donors to human plasma glutathione peroxidase.

Human plasma glutathione peroxidase (GSH-Px) is a distinct extracellular selenoenzyme that detoxifies hydroperoxides when used with GSH in high (mM) non-physiological concentrations. We have discovered that NADPH and human thioredoxin reductase (TR) by itself or with thioredoxin (Trx) are efficient electron donors to this human plasma peroxidase. Incubation of 0.05 microM TR with 0.25 microM GSH-Px, in a system free from GSH, resulted in reduction of t-butyl hydroperoxide. Addition of Trx, 2.5 and 5 microM, respectively, further increased the rate of the reaction. These data were obtained using an assay measuring the oxidation of NADPH. A direct assay demonstrated the formation of cumyl alcohol from cumene hydroperoxide in this GSH-independent peroxidase reaction. Incubation of 0.25 microM GSH-Px with a low concentration of GSH (10 microM), representing the upper level in plasma, plus excess glutathione reductase and NADPH did not result in any reduction of t-butyl hydroperoxide. However, after addition of 2.5 microM human glutaredoxin, a linear peroxidase reaction started. The results suggest that extracellular TR, Trx, or glutaredoxin are reductants for the selenium-dependent peroxidase rather than GSH.

Electron Transport↗