Biomedical subjects
Publications and source records attributed to X Ren.
The ethereal extract from the crude ethanolic extract of Toddalia asiatica was chromatographed on silica gel and tested on biological activity. A crystalline was obtained and confirmed as an active constituent in cardiovascular system. The active constituent was identified as isopimpinellin on the basis of chemical method and spectral analysis.
STUDY DESIGN: The study involves three phases: a clinical study of 30 patients, a biomechanical study to assess the expansion force of a recovering-shape memory expansion clamp, and a biomechanical study using cadaveric specimens to assess the pullout strength of the shape memory expansion clamp as a function of the shape of the clamp. OBJECTIVE: To evaluate the biomechanical effect and clinical application of the shape memory expansion clamp. SUMMARY OF BACKGROUND DATA: The major complication of anterior cervical decompression and fusion was graft dislodgement and pseudarthrosis. Improvement of the shape of bone graft and fusion technique could not eliminate the problem completely. The authors designed the shape memory expansion clamp by using the characteristic of Ni-Ti shape memory alloy and first applied it in an anterior cervical operation. METHODS: The expansion force of recovering of the shape memory expansion clamp was measured in a biomechanical study. Eight fresh human cadaver cervical spine specimens were used to assess the pullout strength of the shape memory expansion clamp as a function of the shape of the clamp. The shape memory expansion clamp had been used to fix rotated circular grafts in 30 cases with cervical spine injuries or cervical spondylosis after anterior decompression. RESULTS: The expansion force of the shape memory expansion clamp in recovery was 4.65-27.96 N, and the pullout strength was 8.82-20.58 N. Bone fusion was achieved in all 30 cases. Dislocation of bone graft, loosening of clamp, or kyphotic deformity had not occurred. CONCLUSION: The expansion force and the pullout strength of the partially recovered shape memory expansion clamp were determined biomechanically. The clinical study demonstrated that the shape memory expansion clamp is safe and effective.
Tottering and leaner, two mutations of the mouse tottering locus, have been studied extensively as models for human epilepsy. Here we describe the isolation, mapping, and expression analysis of Cacnl1a4, a gene encoding the alpha subunit of a proposed P-type calcium channel, and also report the physical mapping and expression patterns of the orthologous human gene. DNA sequencing and gene expression data demonstrate that Cacnl1a4 mutations are the primary cause of seizures and ataxia in tottering and leaner mutant mice, and suggest that tottering locus mutations and human diseases, episodic ataxia 2 and familial hemiplegic migraine, represent mutations in mouse and human versions of the same channel-encoding gene.
Meiotic pairing of the X and Y chromosomes in Drosophila melanogaster males is mediated by the rDNA repeats, which are present in two tandem clusters, one in the centric X heterochromatin and the other near the base of the short arm of the Y chromosome. Deletion of the X chromosomal rDNA cluster disrupts X-Y pairing and causes high frequences of X-Y nondisjunction. Pairing can be partly restored by insertions of cloned complete rRNA genes or by rDNA fragments that include the intergenic spacer (IGS) region. A 240 bp repeated sequence in the IGS was shown to be effective in promoting pairing when present at copy numbers above five. This study further defines the rDNA sequences involved in mediating pairing. Germline insertions of a P element construct containing most of the rDNA transcription unit but no promoter or IGS region were obtained. Two single-copy insertions and four two-copy insertions proved unable to stimulate X-Y disjunction when located on an rDNA-deficient X chromosome. In addition, three insertions of a P element construct consisting of the IGS and promoter regions of the rDNA were characterized molecularly. These three insertions had previously been shown to range in pairing ability from very weak to quite strong. Molecular analysis revealed that the three insertions also vary in copy number of the 240 bp IGS repeat and that these structural differences correlate with the differences in pairing ability. These data indicate that 240 bp repeats are considerably more effective than other regions of the rDNA in stimulating chromosome pairing.
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OBJECTIVE: To explore the role of airway smooth muscle cells (ASMC) stimulated by inflammatory factors in the development of asthma and bronchial hyperresponsiveness (BHR) and the possible mechanism of low dose theophylline in the treatment of airway inflammation, the effects of GM-CSF on endothelin-1 and endothelin converting enzyme (ECE) gene expression in human ASMC and theophylline on their expressions were investigated. METHOD: The cultured human ASMCs were treated with GM-CSF (1,000 micrograms/ml), GM-CSF plus theophylline (125 ng/ml) respectively for 8 hours. Endothelin-1 and ECE gene expresion were measured by RT-PCR. RESULT: There was no ET-1 gene expression in control group, but strong expression in GM-CSF treated group; theophylline entirely inhibited GM-CSF induced ET-1 gene expression in the ASMC; no significant difference of ECE gene expression was found in three groups. CONCLUSION: GM-CSF causes a strong ET-1 gene expression but not ECE gene expression in cultured human airway smooth muscle cells; theophyllin inhibites this abnormal expression which may be one of the anti-inflammatory mechanisms of low dose theophylline in the management of chronic airway inflammation.
OBJECTIVE: To analyze the G6PD gene mutations in several nationalities from Yunnan province. METHODS: G6PD gene mutation of 29 samples from G6PD deficient patients were analyzed by using common and mis-matched primering PCR followed by restriction enzyme digestion. The samples were collected from Yunnan province among several nationalities. RESULTS: In these 29 cases, 20 were of two known mutations, including 19 of 1388 (G-->A) and 1 of 1376 (G-->T) mutation. The 7 cases of national minorities, including 3 of Yi ([symbol: see text]), 2 of Bai ([symbol: see text]), 1 of Dai ([symbol: see text]), and 1 of Naxi ([symbol: see text]), were all 1388 mutations. No report of the G6PD gene 1388 mutation in these ethnic groups was published excepting for Dai. CONCLUSION: The mutation probably had been prevalent before the emergence of these national minorities. The approximate rate of G6PD gene mutations provided in Yunnan province may, in some respects, help to interpret the molecular evolution.
8-hydroxyquinoline complexes of Na(I), Ca(II), Mg(II), Zn(II), Cu(II), Mn(II), Al(III), In(III) and La(III) were synthesized. Photoluminescence (PL) and UV-Vis absorption spectra characteristics of these complexes and 8-hydroxyquinoline are reported. Except complexes of Cu and Mn, most of these complexes reveal photoluminescence. With the polarization force of metal cations increasing, the PL peak shows red-shift and two broad absorption peak in UV-Vis (300-400nm) absorption spectra distinctly appears apart.
The variations of structure and orientation of poly (ethylene terephthalate) (PET) three-dimensional crimp hollow fiber were investigated by infrared attenuated total reflection (IR-ATR) method. It was found that the carbonyl group of this PET hollow fiber orientates vertically to the fiber surface.
FT-IR of the CaC8H4O4 : Ce phosphor prepared by the solution reaction method were determined. Bands of their spectra were assigned. Some structure information about these compounds were given.
The process of apoptosis of BHK-21 cells induced by Sindbis virus (SbV) infection is reported here in details. The nuclear DNA cleavage can be first detected at 6 h after SbV infection, followed by the chromatin margination and condensation at 12 h and the DNA ladder can be detected at 24 h after infection. The details of apoptosis body's formation can be revealed by electron microscopy: First, the outer nuclear membrane protrudes where the condensed chromatin accumulates, then the chromatin get into the budding area with the inner nuclear membrane and separate from the nuclear. Progressively, we cloned the gene of SbV nonstructure protein 2 (nsP2) into the eukaryotic expression vector pMAMneo, and it can be expressed transiently. The DNA cleavages, the basic characteristics of apoptosis also can be detected in some cells. Together with the sequence analysis of nsP2 and the other former results, we conclude that the nsP2 may have direct relation with the SbV-induced apoptosis.
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The choroid plexus, which is responsible for the maintenance of the biochemical milieu of the cerebrospinal fluid (CSF), avidly sequesters Pb. In order to test the hypothesis that chronic Pb exposure may impair choroid plexus function, male weanling Sprague-Dawley rats were exposed to Pb in drinking water at doses of 0, 50, or 250 micrograms Pb/ml (as Pb acetate) for 30, 60, or 90 days. The function of the choroid plexus was assessed as reflected by CSF concentrations of transthyretin (TTR, a major CSF protein manufactured by brain choroid plexus) and CSF essential metal ions (Ca2+, Mg2+, K+, and Na+). TTR concentrations were determined by radioimmunoassay using a monospecific rabbit anti-rat TTR polyclonal antibody, and CSF metal ions analyzed by flame atomic absorption spectrophotometry. Two-way ANOVA of CSF TTR concentrations revealed highly significant dose (p < 0.0001), time (p < 0.0223), and dose-by-time effects (p < 0.0379). Moreover, the percentage of reduction of CSF TTR was directly correlated with Pb concentrations in the choroid plexus (r = 0.703, p < 0.05). Pb exposure significantly increased CSF concentrations of Mg2+, but did not markedly altered CSF concentrations of Ca2+, K+, and Na+. Histopathologic examination under the light microscope did not show distinct alterations of plexus structure in Pb-treated rats. Since TTR is responsible for transport of thyroid hormones to the developing brain, we postulate that the depression of choroid plexus TTR production (and/or secretion) by Pb may impair brain development in young animals by depriving the CNS of thyroid hormones.
The RecA protein is the central enzyme in prokaryotic recombination. It catalyzes pairing and strand exchange between homologous DNA molecules, and functions in both DNA repair and genetic recombination. The RecA-like proteins Rad51 and Dmc1 of yeast are both required for meiotic recombination and the former is also necessary for repair of double-strand breaks in vegetative cells. Genes encoding Rad51 homologs have been isolated recently from several higher eukaryotes. This paper describes the isolation and molecular characterization of a genomic DNA fragment from Drosophila melanogaster containing the coding sequence for a RecA-like protein. This protein exhibits strong sequence homology with the Rad51 proteins of budding yeast, fission yeast, chickens, mouse and humans, and slightly less (but still strong) homology with yeast Dmc1. Both in situ hybridization and Southern analysis indicate that the Rad51 gene is present only once per genome in Drosophila (at 99D on chromosome arm 3R). However, there are at least three other fragments that cross-hybridize strongly at low stringency. RNA blotting analysis detects a single transcript of about 1.35 kb that is present throughout development at low levels. Transcript levels are induced at least tenfold in ovaries, as measured by RNase protection analysis, suggestive of a role in female meiosis. Transcript levels are significantly lower in testes than in bulk RNA of adult males, however, indicating that Rad51 may be repressed in meiosis of Drosophila males.
Acute pulmonary edema was assessed quantitatively in 12 experiments on six anesthetized dogs. Thirty-two copper foil electrodes were placed around each animal's thorax at the level of the third intercostal space. A real-time electrical impedance tomograph was used to form images of the electrical admittivity of the thorax in and near the plane of these electrodes. The lungs were identified by studying the change in admittivity associated with inspiration. Mean admittivity in these lung regions was assessed at 40-min intervals for the next 3-6 hours. In six control experiments, each having a duration of 200 min, the initial admittivity of the lung regions was 102 +/- 16(SD) mS/m. Lung admittivity usually increased during the first 80 min, and then remained within 2 mS/m of its value at 80 min for the remaining 120 min. In six experiments with pulmonary edema, an initial period of change followed by stability was observed. When stability had been attained, 0.07 ml/kg of oleic acid was injected slowly into a central venous site. Five animals received oleic acid, the sixth received a sham injection of saline. In the five receiving oleic acid, lung admittivity rose steadily for the remainder of the experiment. The increase in lung admittivity in these five animals was between 4 and 16 mS/m. In the sham injected experiment, the lung admittivity changed by 1 mS/m. We conclude that impedance imaging can provide semiquantitative assessment of the development of acute pulmonary edema.
OBJECTIVE: To investigate the changes of calcium homeostasis in smooth muscle cells (VSMC) and the role of disturbance of calcium homeostasis in VSMC proliferation after balloon denudation. METHODS: Assay of the cellular incorporation of 3H-leucine and measurement of 45Ca transport were done on the model of balloon-denuded aorta in rat. RESULTS: Endothelial injury induced VSMC proliferation, intimal thickening. After balloon denudation, VSMC calcium influx increased (3 days after balloon denudation, 3.28 +/- 0.14 vs 4.12 +/- 0.28, P < 0.05; 10 days 3.31 +/- 0.09 vs 4.09 +/- 0.21 nmol/10(6) cells, P < 0.01), and calcium efflux decreased, and calcium content increased (3 days after balloon denudation 695 +/- 33 vs 995 +/- 54, P < 0.01; 10 days 709 +/- 32 vs 1022 +/- 94 nmol/10(6) cell, P < 0.01). SR and mitochondria calcium uptake increased. Calcium antagonist, verapamil not only regulated the disturbance of calcium homeostasis, but also inhibited endothelium injury-induced VSMC proliferation. CONCLUSION: The disturbance of calcium homeostasis is probably one of the underlying mechanisms of VSMC proliferation induced by balloon denudation.
OBJECTIVE: Giant cell tumor of bone (GCT) is a comparatively common bone tumor in Chinese. Though GCT is generally considered as a benign tumor, it can pursue an aggressive course. The present study attempts to clarify whether the flow cytometric study can be an useful tool for prognosis of GCT patients. METHODS: DNA content and cell cycle studies on 96 pathologically confirmed GCT specimens and anti-GCT monoclonal antibody (GCF-5 McAb) labeling study on 30 GCTs were made by flow cytometry. RESULTS: 29 GCTs (30.2%) exhibited aneuploid and 67 (69.8%) diploid. Of 71 primary tumors, 16 (22.5%) exhibited aneuploid. The DNA index was 0.97+0.15, and the average S, G2/M phase cells 15.23+6.15%. Of 25 recurrent tumors, 13 (52%) were aneuploid, with an average DI of 1.08+0.17. The average S, G2/M phase cells was 19.56+7.12%. Between the primary and recurrent tumor groups, there was significant statistical difference both in S, G2/M phase cell percentage (P < 0.05) and DNA content (P < 0.01). There was no significant difference between Jaffe's grade I and grade II groups in DNA content or in S, G2/M phase cell percentage. GCF-5 McAb could combine with almost all cells of S, G2/M phase and part of the cells in G0/G1 phase. Significant relationship existed (r=0.468, P < 0.05) between the percentages of S, G2/M phase cells and GCF-5 positive cells. Between the primary and the recurrent tumor groups, there was a significant difference in the percentage of both S, G2/M phase cells and GCF-5 positive cells. CONCLUSION: Apparently flow cytometric study is of value in the evaluation of the biological behavior of GCT as well as the prognosis of the patients.
OBJECTIVE: To observe changes in the content of myocardial angiotensin II and its role in cardiac dysfunction of rat during septic shock. METHODS: Septic shock model was produced by cecal ligation and puncture (CLP) operation on rats. Experimental rats were given captopril 15 mg.kg-1/d per os for 3 days before CLP operation. Mean blood pressure and left ventricular pressure were recorded. Myocardial angiotensin converting enzyme (ACE) activities were determined by a fluorometric assay and myocardial angiotensin II content was measured by radioimmunoassay. Highly purified membrane of sarcoplasmic reticulum (SR) was prepared from rat hearts. Assays were made of ATP-dependent Ca2+ uptake by cardiac SR and (3H) ryanodine binding to SR. RESULTS: Myocardial angiotensin II content increased by 51.5% (P < 0.01) at the 18th hour post CLP, meanwhile there was a decrease in left ventricular +/- dp/dtmax value and the impairment in Ca2+ uptake and (3H) ryanodine binding to cardiac SR. Preliminary administration of captopril reduced myocardial ACE activity and angiotensin II content, but increased left ventricular +/- dp/dtmax value. In comparison to shock group, the initial rate and the capacity of SR Ca2+ uptake were increased by 120% (P < 0.01) and 33.9% (P < 0.05), the Bmax value of (3H) ryanodine binding to SR was also elevated, while the Kd value remained unchanged. CONCLUSIONS: The elevated intracardiac angiotensin II, resulting from the activation of myocardial ACE during sepsis, probably serves as one of the important mediators participating in the pathogenesis of heart failure: the effects of angiotensin II may be associated with the disturbance of Ca2+ transport function of cardiac SR.