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Biomedical subjects

Y Shen

Publications and source records attributed to Y Shen.

At least 379 records · Page 21Linked to original sources
PubMed1997

[CT-ventriculography: a new application of the helical CT].

The authors proposed a new application of helical CT, namely, CT-ventriculography that can obtain 2D and 3D images of different cardiac phases. CT-ventriculography could assess wall motion, systolic thickening and chamber volume. From a single breath hold helical CT 50-rotation), about 500 transaxial slices were obtained by applying overlapping reconstruction (0.1 pitch, 0.08 sec = 0.2 mm interval). All transaxial slices were recordered to separate different cardiac phases. Then, long and short axial 2D tomograms and 3D images in different cardiac phases were reformatted. CT-ventriculography is a promising new application for the assessment of heart function.

Angina Pectoris↗
PubMed1997

[Threshold values of salt in instruction of salt-restricted diet for patients with heart disease].

The low-salt diet was basic means for therapeutic heart diseases. The salt threshold value represented individual's degree of salt taking or dietetic habit. The salt threshold value was measured in 60 patients with essential hypertension, 60 patients with congestive heart failure and 40 normal subjects. The salt threshold value revealed no significant difference in three groups (4.3% +/- 1.6%, 4.0% +/- 1.3% and 4.1% +/- 1.4%, P > 0.05). According to the salt threshold value, 120 patients were classed into three groups: high, middle and low salt threshold value group (n1 = 36, n2 = 74, n3 = 10). The patients were given selective and unitary low-salt diet with random before and after respectively. The results showed that acceptable level of patients to the diet in selective condition was significantly higher than that in unitary condition (81.7% vs 70.8%, P < 0.05). In conclusion, individualized selectivity restriction salt according to salt threshold value had advantage of no reducing appetite, patient's acceptance with ease and cooperative treatments.

Adolescent↗
PubMed1997

[Saline load test for diet instruction in patients with essential hypertension].

The saline loading test was performed in 53 hospitalized patients with essential hypertension. According to Sullivan's standard, 22 of the 53 patients were salt-sensitive (SS), 31 were salt-resistant (SR). The blood pressure in two groups of patients response to salt restriction diet were compared. The results showed that the decrease in level of blood pressure in SS group was higher than that in SR group after salt restriction diet (SS, 23.2 +/- 1.9/14.0 +/- 1.4 vs 21.4 +/- 1.7/13.1 +/- 1.3kPa, P < 0.01-0.05; SR, 23.4 +/- 2.0/14.1 +/- 1.4 vs 23.1 +/- 1.8/13.8 +/- 1.4kPa, P > 0.05). It was concluded that salt restriction diet was stressed on SS than SR patients.

Adult↗
PubMed1997

Guinea pig apolipoprotein C-II: expression in E. coli, functional studies of recombinant wild-type and mutated variants, and distribution on plasma lipoproteins.

Guinea pig apolipoprotein C-II (apoC-II) lacks four amino acid residues in the amino-terminal, lipid-binding part compared to apoC-II from other mammalian species (Andersson et al. 1991. J. Biol. Chem. 266: 4074-4080). To explore whether this structural difference explains the low ability of guinea pig plasma to activate lipoprotein lipase in vitro, we have expressed guinea pig apoC-II in Escherichia coli and have constructed an insertion mutant with the four missing amino acid residues compared to human apoC-II. With a synthetic emulsion of long-chain triacylglycerols, both the wild-type guinea pig apoC-II and the insertion mutant stimulated lipoprotein lipase similar to human apoC-II, but with chylomicrons from an apoC-II-deficient patient, 5- to 10-fold more of both wild-type guinea pig apoC-II and the insertion mutant were needed. Studies of tryptophane fluorescence indicated a slight difference in how guinea pig apoC-II interacted with liposomes, and presumably with lipoproteins, as compared to human apoC-II. The level of apoC-II (11.5 +/- 5.4 microg/ml) was lower in guinea pig compared to human plasma, and most of guinea pig apoC-II was on HDL-like particles. These had decreased ability to donate apoC-II to lipid emulsions compared to human HDL. Some guinea pig apoC-II was associated with LDL which, as demonstrated by surface plasmon resonance, had higher affinity for lipoprotein lipase than human LDL, and inhibited rather than stimulated the lipase reaction in vitro. We conclude that while guinea pig apoC-II is fully competent to stimulate lipoprotein lipase, the sum of several different factors explains the low ability of guinea pig plasma to accomplish stimulation.

Animals↗
PubMed1997

Isolation and identification of berberine from cell cultures of Coptis chinensis.

Calli were formed by the young leaves of Coptis chinensis inoculated onto a 6,7-V solid medium containing 1.0-2.0 mg/L of 2,4-D and 0.1 mg/L of kinetin. The loose calli were chosen and transferred into a liquid medium and free cells and cell aggregates were obtained. Cell lines with a higher content of berberine were selected by irradiation of suspension culture and a plate-screening technique. After 35 subcultures, the selected cell lines were cultured in a larger quantity for the extraction of alkaloids. Yellow crystals were obtained from the extracts and identified as berberine by TCL, UV and IR absorption, and mass spectrography. They have the same molecular structure and anti-bacterium activities as the berberine obtained from natural plants.

Berberine↗
PubMed1997

[Screening and genetic analysis of fragile X syndrome in Tongling Anhui province of China].

OBJECTIVE: To investigate the prevalence of fragile X syndrome in the Chinese. METHODS: Fragile X syndrome was screened from 172,600 people living in Tongling city, Anhui province. Suspected patients were tested by PCR and Southern Blotting. RESULTS: Seven of 88 mental handicap children were found with fra (X), including 3 female and 4 male patients. Six patients, 3 normal transmitting males and 5 carriers were found in detailed search in these 6 fra (X) families. Genetic linkage analyses of 2 of the families were reported here. CONCLUSION: The prevalence of fragile X syndrome in the Chinese is not apparently different from the previous reports on the Caucasian population.

Child, Preschool↗
PubMed1996

A tumor-specific Th2 clone initiating tumor rejection via primed CD8+ cytotoxic T-lymphocyte activation in mice.

We established a CD4+ T-cell clone specific for syngeneic methylcholanthrene-induced sarcoma, S1509a raised in an A/J mouse, involved in tumor regression. The phenotype of the T-cell clone was CD3+, TCR-beta+, CD4+, CD45RB+, LFA-1+, ICAM-1+, CD44+, and VLA-4+. The CD4+ T-cell clone specifically proliferated through antigen stimulation with attenuated S1509a in the presence of syngeneic accessory cells, and this antigen-induced proliferation was inhibited with anti-CD4 and anti-I-Ek monoclonal antibodies. The CD4+ T-cell clone designated YS1093 secreted interleukin (IL) 4, IL-5, and IL-6, but not IFN-gamma, tumor necrosis factor alpha, or IL-2, thus indicating that the clone belongs to the Th2 type. YS1093 cells and their culture supernatant after antigen stimulation augmented the primed cytotoxic T lymphocyte killing activity at the effector phase. YS1093 cells having Th2-type characteristics made the homologous growing tumor regress in the tumor-bearing syngeneic mice when YS1093 cells were transferred into the tumor-bearing mice i.v. The in vivo tumor regression initiated by YS1093 cell transfer essentially required the presence of CD8+ T cells in the tumor-bearing hosts, thus suggesting that some specific Th2 cells are positively involved in tumor regression by activating primed CD8+ cytotoxic T lymphocytes against the homologous tumor in situ.

Adoptive Transfer↗
PubMed1996

Molecular mechanisms governing tumor-necrosis-factor-mediated regulation of plasminogen-activator inhibitor type-2 gene expression.

Plasminogen-activator inhibitor type 2 (PAI-2), a serine protease inhibitor involved in the regulation of urokinase-dependent proteolysis, is also implicated in the inhibition of tumor-necrosis-factor-(TNF)-mediated apoptosis. The PAI-2 gene is one of the most TNF-responsive genes known and is also highly induced by the phorbol ester phorbol 12-myristate 13-acetate (PMA) and the phosphatase inhibitor, okadaic acid, in both HT-1080 fibrosarcoma and U-937 histiocytic cells. We sought to identify and characterize regulatory cis-acting DNA elements and trans-acting factors which mediate basal and inducible PAI-2 gene transcription. A series of promoter deletion mutants (nucleotides -1859 to -91) fused to the chloramphenicol acetyl transferase (CAT) reporter gene were transfected into HT-1080 cells. Two repressor regions were identified; one distally between positions -1859 and -1100, and one proximally between positions -259 and -219. Cells transfected with constructs harboring more than 259 bp promoter sequence produced a 10-15-fold increase in CAT activity when treated with PMA or okadaic acid, but produced only a minimal (2.5-fold) increase in response to TNF. Removal of the proximal repressor by deletion to position -219, or by internal deletion from the -1100 PAI-2 CAT construct, resulted in a selective increase in TNF responsiveness, suggesting that induction of PAI-2 gene transcription by TNF is associated with derepression. Detailed analysis of the proximal repressor utilizing the electrophoretic mobility shift assay (EMSA), identified two novel and distinct protein-binding sites (A and B). Site A is located within the 40-bp proximal repressor while site B is situated immediately adjacent to the 3' boundary. Treatment of cells with PMA or okadaic acid produced no change in the binding activity of proteins recognising sites A or B. However, treatment of cells with TNF results in a profound selective reduction in site-B-binding activity, suggesting that this site plays a significant role in TNF-mediated regulation of PAI-2 gene expression. Our findings suggest that TNF-mediated induction of PAI-2 gene expression involves derepression and is associated with cis-acting and trans-acting factors located within and adjacent to the proximal repressor region.

Base Sequence↗
PubMed1996

Elevated soluble Fas (sFas) levels in nonhematopoietic human malignancy.

Fas is a widely expressed membrane-anchored protein that induces apoptosis. Soluble Fas (sFas), generated by alternative mRNA splicing, can antagonize cell-surface Fas function. We have investigated sFas in 104 cancer patients with nonhematopoietic malignancies using a Fas-specific ELISA and immunoprecipitation. Our studies demonstrate an elevated 40-42-kDa sFas species in both patient serum and tumor explants. These observations provide the first evidence that sFas is increased in patients with solid tumors in a manner reflective of disease stage and tumor burden and argue that sFas can be synthesized and released both systemically and locally within the tumor microenvironment.

Antigens, Neoplasm↗
PubMed1996

Alternative splicing of the FMR1 gene in human fetal brain neurons.

The alternative splicing expression of the FMR1 gene was reported in several human and mouse tissues. Five regions of FMR1 gene can be alternatively spliced, but the combination of them has not been investigated fully. We reported here the analysis of alternative splicing pattern of the FMR1 gene in cultured fetal human neurons, using a RT-PCR and cloning strategy. Eleven splicing types were cloned and different isoforms were not equally represented. The dominant isoform represents nearly 40%, and the other isoforms were relatively rare. One isoform has a different carboxylterminus. Most of the alternative spliced regions appear hydrophilic; thus, they may locate on the surface of the FMR1 protein.

Alternative Splicing↗
PubMed1996

A survey of FRAXE allele sizes in three populations.

FRAXE is a fragile site located at Xq27-8, which contains polymorphic triplet GCC repeats associated with a CpG island. Similar to FRAXA, expansion of the GCC repeats results in an abnormal methylation of the CpG island and is associated with a mild mental retardation syndrome (FRAXE-MR). We surveyed the GCC repeat alleles of FRAXE from 3 populations. A total of 665 X chromosomes including 416 from a New York Euro-American sample (259 normal and 157 with FRAXA mutations), 157 from a Chinese sample (144 normal and 13 FRAXA), and 92 from a Finnish sample (56 normal and 36 FRAXA) were analyzed by polymerase chain reaction. Twenty-seven alleles, ranging from 4 to 39 GCC repeats, were observed. The modal repeat number was 16 in the New York and Finnish samples and accounted for 24% of all the chromosomes tested (162/665). The modal repeat number in the Chinese sample was 18. A founder effect for FRAXA was suggested among the Finnish FRAXA samples in that 75% had the FRAXE 16 repeat allele versus only 30% of controls. Sequencing of the FRAXE region showed no imperfections within the GCC repeat region, such as those commonly seen in FRAXA. The smaller size and limited range of repeats and the lack of imperfections suggests the molecular mechanisms underlying FRAXE triplet mutations may be different from those underlying FRAXA.

Alleles↗
PubMed1996

Mechanism of the systemic, left ventricular, and coronary vascular tolerance to a binge of cocaine in conscious dogs.

BACKGROUND: Prior experimental studies have emphasized the cardiovascular effects of acute, single doses of cocaine. However, cardiovascular complications are most often reported in chronic users, who have been exposed to repetitive doses of cocaine. It remains unclear whether there is tolerance or sensitization to the systemic, left ventricular, and coronary hemodynamic effects of a binge of cocaine. METHODS AND RESULTS: We studied 11 conscious, chronically instrumented dogs to determine the systemic pressor, inotropic, chronotropic, and coronary vascular resistance responses to cocaine (1 mg/kg IV) administered every 25 minutes for five doses. There was progressive tolerance to the systemic pressor (mean arterial pressure: first dose, +42 +/- 4% from 97 +/- 2 mm Hg; fifth dose, +8 +/- 3% from 116 +/- 7 mm Hg; P < .01) and heart rate (first dose, +45 +/- 8% from 93 +/- 5 bpm; fifth dose, +8 +/- 2% from 109 +/- 9 bpm; P < .01) responses and abolition of the positive inotropic (left ventricular dP/dt: first dose, +19 +/- 4% from 2824 +/- 75 mm Hg/s; fifth dose, -3 +/- 5% from 2531 +/- 436 mm Hg/s; P < .01) and coronary vasoconstrictor (coronary vascular resistance: first dose, +38 +/- 9% from 1.9 mm Hg.mL-1.min-1; fifth dose, -7 +/- 2% from 2.6 +/- 0.2 mm Hg. mL-1.min-1; P < .01) responses to a binge of cocaine despite progressive increases in peak plasma cocaine concentrations. In contrast, both the plasma norepinephrine and epinephrine responses were attenuated with repetitive exposure to cocaine, whereas myocardial alpha and beta-adrenergic responsiveness was maintained. CONCLUSIONS: Repetitive cocaine administration is associated with the development of early and progressive tolerance to systemic, left ventricular, and coronary vascular effects of cocaine. The mechanism of the tolerance involves neither impaired myocardial nor coronary vascular responsiveness to adrenergic stimulation but, rather, attenuated catecholamine responses to repetitive cocaine administration.

Animals↗
PubMed1996

Characterization and genomic mapping of genes and pseudogenes of a new human protein tyrosine phosphatase.

Previously described protein tyrosine phosphatases (PTPs) are classified into three types according to their sequence homology and structural features. Here we describe the characterization of genes and pseudogenes of a member of a fourth type of PTP, designated protein tyrosine phosphatase 4A (PTP4A). The 167-amino-acid human PTP4A bears the signature active site of all PTPs, but does not show any other sequence homology to any of the previously described PTPs. Two cDNAs encoding PTP4A that differed in their noncoding regions were isolated. Another cDNA that has a high level of sequence identity with these two cDNAs and a deletion in the coding region was also isolated. Northern analysis using a probe from a common 3'-untranslated region of the cDNAs recognized mRNAs of about 2 and 4 kb. Both species of mRNA were seen in all human adult and fetal tissues tested. Fluorescence in situ hybridization mapping of the corresponding yeast artificial chromosome clones and sequence-tagged site analysis suggested that one of the PTP4A coding genes is located at 1p35 and the other is on chromosome 11. A processed pseudogene for PTP4A was found in the BRCA1 region of 17q21 and shares 96% sequence identity to one of the PTP4A coding cDNAs. Our studies also suggest the existence of another processed pseudogene on chromosome 11.

Adult↗
PubMed1996

"Bailout" coronary stenting in patients with a recent myocardial infarction.

Patients who underwent bailout intracoronary stenting within 7 days of a myocardial infarction had lower clinical and angiographic success rates and a higher incidence of emergent coronary artery bypass graft surgery than patients who underwent bailout stenting without a history of a recent myocardial infarction. In addition, there was a trend toward more cardiac events after discharge in patients who received stents after a recent myocardial infarction.

Aged↗
PubMed1996

A serotonin receptor gene (5HT1A) variant found in a Tourette's syndrome patient.

Serotonergic pathway disturbances have been implicated in neuropsychiatric disorders such as Tourette's syndrome (TS), substance abuse, and depression. In order to search for the presence of an association between these neuropsychiatric disorders and particular serotonin receptors isolated from these patients, we have started to analyze the structure of these receptor genes. We now report that a missense nucleotide change in the 5HT1A receptor gene produces a variant form of the 5HT1A receptor (Arg(219) to Leu) identified in DNA extracted from a TS patient. Also, in several DNA samples examined, both in controls and in the patients, we found a second missense nucleotide change which resulted in an amino acid change (Asn(417) to Lys) located in the carboxyl tail of the receptor. Several other polymorphic changes have been reported previously in the human 5HT1A receptor and we have also confirmed these findings in our samples.

Alcoholism↗