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Biomedical subjects

P Jiang

Publications and source records attributed to P Jiang.

At least 91 records · Page 5Linked to original sources
PubMed1997

[The effect of far infrared rays on the survival of randomized skin flap in the rat: an experimental study].

In order to observe the effect of far infrared rays on the survival of skin flap, the following experiment was performed. Forty-eight SD rats were selected and divided into two groups. The rats received 0.3 w/cm2 radiation twice a day from 3 days before operation to 5 days after operation in the experimental group, while in the control group the rats received none before or after the operation. The flap was designed as 2 cm x 6 cm in the back of the rats with the pedicle caudalward. The microcirculatory changes of the flap were observed, and the survival area of the flap was calculated. The results showed that either in the proximal or in the distal part of the graft, in the experimental group, the mean opening rate, diameter and the flowing velocity of the microvessels were significantly higher than those in the control group (P < 0. 05). The mean rate of survival area of the experimental group (80.5%) was also higher than that of the control group (62.7%) (P < 0.01). It was suggested that radiation with far infrared rays could dilate the microvessels, improve the flap microcirculation, therefore, enhance the survival of the randomized skin flap.

Animals↗
PubMed1996

Identification of a novel hypothalamic neuropeptide Y receptor associated with feeding behavior.

Neuropeptide Y (NPY) plays important roles in the central control of appetite and energy balance, but the receptor subtype responsible for this function has not been cloned. Here we report the cloning by expression of a novel NPY receptor subtype from a rat hypothalamus cDNA library. The novel receptor, referred to as the NPY Y5 receptor, has a transcript of approximately 2.6 kilobases with an open reading frame of 1335 base pairs that encodes a 445-amino acid protein. The amino acid sequence deduced from the rat Y5 cDNA clone shows only 30-33% identity to other NPY receptors, including Y1, Y2, and Y4/PP1. Using the rat Y5 receptor cDNA probe, the human homologue was obtained by low stringency hybridization. The human Y5 amino acid sequence has 88% identity to the rat Y5 receptor. Importantly, pharmacological analysis shows that the rat and human Y5 receptors have high affinity for the peptides that elicit feeding (e.g. NPY, PYY, (2-36)NPY, and (LP)NPY) and low affinity for nonstimulating peptides (e.g. (13-36)NPY and rat PP), suggesting that it is the NPY feeding receptor subtype.

Amino Acid Sequence↗
PubMed1996

Generation of an integrated transcription map of the BRCA2 region on chromosome 13q12-q13.

An integrated approach involving physical mapping, identification of transcribed sequences, and computational analysis of genomic sequence was used to generate a detailed transcription map of the 1. 0-Mb region containing the breast cancer susceptibility locus BRCA2 on chromosome 13q12-q13. This region is included in the genetic interval bounded by D13S1444 and D13S310. Retrieved sequences from exon amplification or hybrid selection procedures were grouped into physical intervals and subsequently grouped into transcription units by clone overlap. Overlap was established by direct hybridization, cDNA library screening, PCR cDNA linking (island hopping), and/or sequence alignment. Extensive genomic sequencing was performed in an effort to understand transcription unit organization. In total, approximately 500 kb of genomic sequence was completed. The transcription units were further characterized by hybridization to RNA from a series of human tissues. Evidence for seven genes, two putative pseudogenes, and nine additional putative transcription units was obtained. One of the transcription units was recently identified as BRCA2 but all others are novel genes of unknown function as only limited alignment to sequences in public databases was observed. One large gene with a transcript size of 10.7 kb showed significant similarity to a gene predicted by the Caenorhabditis elegans genome and the Saccharomyces cerevisiae genome sequencing efforts, while another contained a motif sequence similar to the human 2',3' cyclic nucleotide 3' phosphodiesterase gene. Several retrieved transcribed sequences were not aligned into transcription units because no corresponding cDNAs were obtained when screening libraries or because of a lack of definitive evidence for splicing signals or putative coding sequence based on computational analysis. However, the presence of additional genes in the BRCA2 interval is suggested as groups of putative exons and hybrid selected clones that were transcribed in consistent orientations could be localized to common physical intervals.

BRCA2 Protein↗
PubMed1996

The complete BRCA2 gene and mutations in chromosome 13q-linked kindreds.

Breast carcinoma is the most common malignancy among women in developed countries. Because family history remains the strongest single predictor of breast cancer risk, attention has focused on the role of highly penetrant, dominantly inherited genes in cancer-prone kindreds (1). BRCA1 was localized to chromosome 17 through analysis of a set of high-risk kindreds (2), and then identified four years later by a positional cloning strategy (3). BRCA2 was mapped to chromosomal 13q at about the same time (4). Just fifteen months later, Wooster et al. (5) reported a partial BRCA2 sequence and six mutations predicted to cause truncation of the BRCA2 protein. While these findings provide strong evidence that the identified gene corresponds to BRCA2, only two thirds of the coding sequence and 8 out of 27 exons were isolated and screened; consequently, several questions remained unanswered regarding the nature of BRCA2 and the frequency of mutations in 13q-linked families. We have now determined the complete coding sequence and exonic structure of BRCA2 (GenBank accession #U43746), and examined its pattern of expression. Here, we provide sequences for a set of PCR primers sufficient to screen the entire coding sequence of BRCA2 using genomic DNA. We also report a mutational analysis of BRCA2 in families selected on the basis of linkage analysis and/or the presence of one or more cases of male breast cancer. Together with the specific mutations described previously, our data provide preliminary insight into the BRCA2 mutation profile.

BRCA2 Protein↗
PubMed1996

Transcriptional activation of the human epidermal growth factor receptor promoter by human p53.

The human epidermal growth factor receptor (EGFR) promoter is activated by both wild-type and tumor-derived mutant p53. In this communication, we demonstrate that EGFR promoter sequence requirements for transactivation by wild-type and mutant p53 are different. Transient-expression assays with EGFR promoter deletions identified a wild-type human p53 response element, 5'-AGCTAGACGTCCGGGCAGCCCCCGGCG -3', from positions --265 to --239. Electrophoretic mobility shift analysis and DNase I footprinting assays indicated that wild-type p53 binds sequence specifically to the response element. Using circularly permuted DNA fragments containing the p53-binding site, we show that wild-type p53 binding induces DNA bending at this site. We further show that the EGFR promoter is also activated by tumor-derived p53 mutants p53-143A, p53-175H, p53-248W, p53-273H, and p53-281G. However, the transactivation by mutant p53 does not require the wild-type p53-binding site. The minimal EGFR promoter from positions --104 to --20 which does not contain the wild-type p53-binding site is transactivated by the p53 mutants but not by the wild-type protein, showing a difference in the mechanism of transactivation by wild-type and mutant p53. Transactivation of the EGFR promoter by p53 may represent a novel mechanism of cell growth regulation.

Amino Acid Sequence↗
PubMed1996

[A primary study on treatment of intracranial hematomas with specially designed needle puncture].

We treat hematomas by special designed needles and other techniques for breaking and liquefying hematoma. This method is easy to learn and needn't operation room, even can be done at the patient's bedside. Its merits the included point wound without craniotomy, low medical cost and satisfactory result. We treat 112 patients with hypertensive intracranial hematomas, 25 patients with acute epidural hamatoma and 17 patients with hematoma due to other causes. In the total of 154 patients, 20 had brain herniations and 104 coma. The mortality was very low (8.44%). 94 patients (91.34%) woke up in 1 to 2 weeks.

Cerebral Hemorrhage↗
PubMed1996

[Flavanonol glucosides of Smilax glabra Roxb].

Three flavanonol glucosides have been isolated from the rhizome of Smilax glabra. Their structures were identified as isoengetitin, isoastilbin and astilbin on the basis of their physicochemical and spectral data. Full as signment of their 1HNMR and 13CNMR chemical shift signals was established by various 2D-NMR techniques. Their glucosidic bond structures were determined for the first time. Isoastilbin was isolated from Smilax for the first time.

Drugs, Chinese Herbal↗
PubMed1995

Genomic structure, expression and mutational analysis of the P15 (MTS2) gene.

The P15 gene (MTS2) encodes a cyclin-dependent kinase (CDK) inhibitor with considerable sequence identity and biochemical similarity to the CDK inhibitor p16. It is closely linked to the P16 gene (MTS1) and is homozygously deleted in many tumor cell lines. These features suggest that p15 may be a tumor suppressor. We have determined the genomic structure of P15 and examined its pattern of mRNA expression. In addition, we have shown that ectopic expression of p15 inhibits growth of tumor-derived cell lines. We have also searched for P15 mutations in tumor cell lines and in 9p21-linked melanoma kindreds. Other than the previously described homozygous deletions, no mutations of P15 were found. Collectively, these observations suggest a role for p15 in growth regulation, but a limited role for p15 in tumor progression.

Base Sequence↗
PubMed1995

Complex structure and regulation of the P16 (MTS1) locus.

The p16 gene (P16, MTS1, CDKN2) encodes a negative regulator of the cell cycle. Molecular genetic techniques have been used to explore the role of p16 in normal development and cancer. Two transcripts derived from the p16 gene with distinct protein coding potentials are described. The previously undescribed transcript form has the same exons 2 and 3 as the p16-encoding mRNA but contains a different exon 1. The human p16 transcripts are detected in various tissues, and the ratio of the transcripts is regulated in both a tissue-specific and cell cycle-specific manner. The P16-derived mRNAs are probably generated from separate promoters, and transcription from one of the promoters appears to be regulated, at least in part, by the retinoblastoma gene product.

Base Sequence↗
PubMed1995

Comparative analysis of Homo sapiens and Mus musculus cyclin-dependent kinase (CDK) inhibitor genes p16 (MTS1) and p15 (MTS2).

Cyclin-dependent kinase inhibitors are a growing family of molecules that regulate important transitions in the cell cycle. At least one of these molecules, p16, has been implicated in human tumorigenesis while its close homolog, p15, is induced by cell contact and transforming growth factor-beta (TGF-beta). To investigate the evolutionary and functional features of p15 and p16, we have isolated mouse (Mus musculus) homologs of each gene. Comparative analysis of these sequences provides evidence that the genes have similar functions in mouse and human. In addition, the comparison suggests that a gene conversion event is part of the evolution of the human p15 and p16 genes.

Amino Acid Sequence↗
PubMed1995

[Effect of glucocorticoids and other steroids on arginine vasopressin release from rat hypothalamic slices].

Rat hypothalamic slices sectioned with vibratome (containing paraventricular and supraoptic nuclei) were incubated in static microchamber and the Arginine vasopressin (AVP) released from the slices was measured by radioimmunoassay. The effect of glucocorticoids (GC) and other steroids on AVP release was investigated. The results were as follows: (1) AVP was steadily released at a rate of 9.06 +/- 1.23 pg/min for as long as 6 h (not including the 90 min for recovery of slices). (2) Corticosterone (B) inhibited AVP release within 20 min in a dose-dependent manner from 10(-7) to 10(-4) mol/L. (3) Cortisol, 17 beta-estradiol, or testosterone (10(-6) mol/L) also inhibited AVP release within 20 min, but dexamethasone, aldosterone, progesterone, RU486, or cholesterol had no significant effect. (4) RU486 (10(-5)-10(-3) mol/L) could partially block the rapid inhibitory effect of corticosterone. These results suggested that GC might exert in situ a regulatory negative feedback action on the AVP release from hypothalamus of rat through a non-genomic rather than a genomic mechanism.

Animals↗
PubMed1995

[Experimental study of radioimmunotherapy for xenograft of human esophageal carcinoma].

Using nude mice bearing human esophageal carcinoma strain Eca 109 as models of tumor, we tested the therapeutic efficiency of 131I labelled monoclonal antibody MGb2 A 4-week experimental study was carried out in 5 treatment groups: group A, buffer, group B, unlabelled MGb2; group C, 131I-labelled normal mice IgG and group D, 131I-labelled MGb2 18.5MBq. All nude mice above were given agents intraperitoneally. In group E, the animals were given 131I-labelled MGb2 18.5MBq by intratumoral administration. The results showed that from the second week, in group D and E the tumor volume was remarkably decreased as compared with that of the other 3 groups (P < 0.01 or P < 0.05). In the fourth week the mean volume in group D and E were 0.55 cm3 and 0.23cm3, while in group A, the volume was 1.43cm3. The inhibition rate of tumor growth in group D and E was higher than in other groups from the second week (P < 0.01), especialy in the third and fourth week with a mean value of 62. 4%, 61.5% and 82.2%, 83.9% respectively. There were no significant differences between group A, B, and C in tumor volume or growth inhibition rate.

Animals↗
PubMed1995

[A comparative study on the chemical constituents of cultivated and wild fructus Gardeniae].

Studies have been made on the preliminary tests of the chemical constituents of cultivated and wild Fructus Gardeniae on the comparative analysis of the thin-layer chromatograms, IR and UV spectra of 95% ethanolic extracts as well as extracts obtained with four different solvents, and on the content determination of gardenosides. The results reveal that the cultivated and wild Fructus Gardeniae have similar chemical constituents, but differ in the contents of some constituents.

Chromatography, Thin Layer↗
PubMed1994

Method for determining the reliable prediction(s) of compositions of tissue phantoms.

In a previous paper, we showed that mixture laws can be used to predict the compositions of tissue phantoms. Due to the variation in the performance of the mixture laws when they are applied to phantoms, however, it is difficult to determine which predictions of the composition are most reliable. In this paper, we study the causes of the variation in the performances of different sets of mixture laws, and propose a criterion for choosing a reliable predictor. The predictions selected with the proposed criterion agree very well with the known compositions of phantoms. The potential uses of the mixture methodology and the criterion to tissue characterization are discussed.

Models, Structural↗
PubMed1994

The effect of hypothermia on transient focal ischemia in rat brain evaluated by diffusion- and perfusion-weighted NMR imaging.

The effect of moderate whole-body hypothermia (30 degrees C) on transient middle cerebral artery (MCA) occlusion in the rat was evaluated using diffusion- and perfusion-weighted magnetic resonance imaging. Two hours of transient MCA occlusion was induced by intracarotid insertion of a nylon filament under normothermic (n = 14) and hypothermic (n = 7) conditions. Diffusion- and perfusion-weighted imaging were performed before, during, and after focal ischemia from 30 min up to 7 days. In hypothermic animals, scattered neuronal necrosis was localized to select areas of the caudate putamen and the parietal and insular cortex. In contrast, the normothermic ischemic animals exhibited pan-necrosis and infarct encompassing the damaged area. The diffusion and perfusion data measured from caudate putamen indicate that hypothermia causes a significant reduction in the apparent diffusion coefficient of water (ADCw) and CBF values from normothermic control values (p < 0.01). In both normothermic and hypothermic animals after onset of MCA occlusion, ADCw and CBF values in the core of the ischemic region (striatum) significantly declined from the preischemic and homologous contralateral control ADCw and CBF values (p < 0.05). However, ADCw and CBF in the hypothermic group returned toward control more rapidly than in the normothermic group. These results suggest that the protective effect of hypothermia on ischemic cell damage is reflected in the early return of ADCw during reperfusion and the reduction of ischemic cell damage by hypothermia may be mediated by the improved CBF during acute reperfusion.

Animals↗
PubMed1994

Inhibition of fatty acid synthesis in Escherichia coli in the absence of phospholipid synthesis and release of inhibition by thioesterase action.

The effects of inhibition of Escherichia coli phospholipid synthesis on the accumulation of intermediates of the fatty acid synthetic pathway have been previously investigated with conflicting results. We report construction of an E. coli strain that allows valid [14C]acetate labeling of fatty acids under these conditions. In this strain, acetate is a specific precursor of fatty acid synthesis and the intracellular acetate pools are not altered by blockage of phospholipid synthesis. By use of this strain, we show that significant pools of fatty acid synthetic intermediates and free fatty acids accumulate during inhibition of phospholipid synthesis and that the rate of synthesis of these intermediates is 10 to 20% of the rate at which fatty acids are synthesized during normal growth. Free fatty acids of abnormal chain length (e.g., cis-13-eicosenoic acid) were found to accumulate in glycerol-starved cultures. Analysis of extracts of [35S]methionine-labeled cells showed that glycerol starvation resulted in the accumulation of several long-chain acyl-acyl carrier protein (ACP) species, with the major species being ACP acylated with cis-13-eicosenoic acid. Upon the restoration of phospholipid biosynthesis, the abnormally long-chain acyl-ACPs decreased, consistent with transfer of the acyl groups to phospholipid. The introduction of multicopy plasmids that greatly overproduced either E. coli thioesterase I or E. coli thioesterase II fully relieved the inhibition of fatty acid synthesis seen upon glycerol starvation, whereas overexpression of ACP had no effect. Thioesterase I overproduction also resulted in disappearance of the long-chain acyl-ACP species. The release of inhibition by thiosterase overproduction, together with the correlation between the inhibition of fatty acid synthesis and the presence of abnormally long-chain acyl-ACPs, suggests with that these acyl-ACP species may act as feedback inhibitors of a key fatty acid synthetic enzyme(s).

Acetates↗