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Biomedical subjects

D Sun

Publications and source records attributed to D Sun.

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

[Relationship between left cardiac function and oxygen transport of cor pulmonale during acute attack at high altitude].

OBJECTIVE: Relationship between left cardiac function and oxygen transport in the patients with cor pulmonale during acute attack at high altitude was studied to benefit prevention and treatment of cor pulmonale. METHOD: 20 cases were divided into 16 as a surviving group and 4 as a death group. CO was determined by Swan-Ganz catheter from internal carotid vein to pulmonary artery directly. RESULT: (1) CI in the patients decreased (2.9 +/- 0.4 L.min-1.m-2). mPAP (4.9 +/- 1.3 kPa) and PAWP (1.5 +/- 0.8 kPa) increased. LVSWI (35 +/- 11 g.cm-1.min-1) dropped. (2) above Indicies in surviving group improved after comprehensive treatment. CI and LVSWI increased. But LVSWI in death group continued to decline. mPAP and PAWP were not changed; (3) There was significant corelation between LVSVI and DO2(r = 0.4318, P < 0.05). CONCLUSION: LVSWI of cor pulmonale could affect DO2 level directly and closely relate to prognosis.

Aged↗
PubMed1998

[Sulfation of polysaccharides isolated from Indocalamus tesselatus and their anticytopathic effect on human immunodeficiency virus type I].

For preparation of sulfated polysaccharides isolated from bamboo leaves (Indocalamus tesselatus) with chlorosulfonic acid-pyridine, the experimental conditions as the molar ratio of reactants and temperature and time of reaction were discussed. A homogeneous sulfation method with good yield of more than 80% was obtained and the sufur content was found to be 21.9%. Conformation change in sulfated polysaccharide with changes of intrinsic viscosity, polarimetery and CD spectra were found to be related to the negative charge. The polysaccharide sulfates were shown to have better activity to inhibit cytopathic effect of human immunodeficiency virus(HIV) infection than native polysaccharides. The effective concentration was 10 micrograms.ml-1 while the cytotoxic concentration was 2.5 mg.ml-1.

Antiviral Agents↗
PubMed1998

[Detection of Brugia malayi larva in mosquito vector by PCR and PCR-ELISA].

AIM: To develop sensitive, specific, simple assays for the detection of Brugia malayi larva in mosquito vectors. METHODS: The optimum conditions for PCR and PCR-ELISA were determined. With dissected larvae, detection limits and as well as specificities of the two assays were worked out. The optimized assays were then tested with infected and non-infected mosquito vectors, Anopheles sinensis. RESULTS: Both PCR and PCR-ELISA detected DNA equivalent to a single L1-stage larva(L1). While the actual detecting limits of the two, as estimated and titrated respectively, reached to 1/10 and 1/100 of a L1. When the two assays were used to detect the larvae isolated from 113 infected A. sinensis, all gave specific bands and positive reactions. However, trials on direct amplifications with crude extracts of infected mosquito vectors consistently failed to give specific bands upon electrophoresis and negative results in PCR-ELISA as well. CONCLUSION: Both PCR and PCR-ELISA were preliminarily established for the detection of isolated B. malayi larva in mosquito vector, which proved to be sensitive, specific and easy to manipulate.

Animals↗
PubMed1998

[Correction of spectral interferences in inductively coupled plasma atomic emission spectrometry with a modified chemometric method based on matrix projection].

A modified chemometric method based on matrix projection was developed to correct the spectral interferences in inductively coupled plasma atomic emission spectrometry (ICP-AES). The accuracy of the correction was significantly improved by reevaluating the residuals. The excellent analytical results for some rare earth elements proved the method fairly feasible.

English Abstract↗
PubMed1998

[Influences of Freon-12 (CF2CCl2) on the electron number densities in an inductively coupled plasma (ICP) measured with Halpha line--the applications of ICP in the disposal of hazardous waste].

The inductively coupled plasma was applied to decompose Freon 12 (CF2CCl2). The efficiency of the decomposition was indirectly evaluated by comparing the electron number densities in the central channel of the ICP with the addition of different amounts of Freon-12. Halpha line (656.3nm) was used to measure the electron number density due to Hbeta line (486.1nm) is seriously interfered with the addition of Freon-12 under the selected operating conditions. The "thermal pinch" effect was found with the addition of Freon-12, which is beneficial to the complete decomposition of the compound.

English Abstract↗
PubMed1998

Patterns of allelic loss (LOH) in vulvar squamous carcinomas and adjacent noninvasive epithelia.

The pathogenesis of carcinoma of the vulva is diverse and includes both human papilloma virus (HPV)-positive and HPV-negative pathways. The objective of this study was to correlate the morphology with patterns of loss of heterozygosity (LOH) within four vulvar carcinomas and in adjacent vulvar epithelia. Tumors were categorized as HPV positive or negative by polymerase chain reaction (PCR) analysis. Forty-one different sites of normal squamous mucosa, hyperplasia, vulvar intraepithelial neoplasia (VIN), and carcinoma were microdissected in duplicate, and each extracted DNA was analyzed in duplicate for LOH at 10 chromosomal loci by PCR and polyacrylamide gel electrophoresis. Patterns of LOH were compared within different sites of tumors and between the tumor and the noninvasive epithelia. Of three tumors with multiple invasive foci analyzed, divergent patterns of LOH were identified in two, correlating in one with differences in tumor grade. In one HPV-16-positive case, multiple sites of VIN displayed heterogeneity for LOH consistent with divergent clonal or subclonal populations, some of which were not shared by the tumor. In one HPV-negative case, LOH was found in foci of hyperplasia and differentiated VIN (atypical hyperplasia), the latter sharing LOH with the invasive carcinoma at some but not all chromosomal loci. This study suggests that a genetic relationship exists between VIN and carcinoma, irrespective of HPV involvement. It also suggests that in HPV-negative tumors, allelic loss may predate the onset of invasive carcinoma and, in some cases, cellular atypia (VIN). However, the divergent patterns of LOH observed imply that many genetic alterations in the adjacent vulvar epithelium are not directly related to the invasive carcinoma.

Carcinoma in Situ↗
PubMed1998

Telomerase activity of sarcoma cell lines and fibroblasts is independent of p53 status.

Telomerase activity is necessary for the stabilization of telomeres, which function to overcome cellular senescence and are linked to unlimited cell proliferation. Activation of telomerase is characteristic of immortalized cell lines and most tumors. The p53 gene has been implicated as a crucial barrier to unlimited cell proliferation, and its absence has been shown to allow direct immortalization of cells by certain oncogenes. The p53 gene may have an additional function of signaling cell growth arrest in response to telomere shortening, which occurs with repeated cellular divisions and ultimately threatens chromosomal stability. This prompted us to consider whether the enzyme telomerase, responsible for adding new telomeres to chromosomal ends, may be affected by the p53 status of normal and malignant cells. We investigated whether a relationship between telomerase and p53 could be demonstrated in a human sarcoma cell line containing a missense p53 mutation and several stable transfectants that express the wild-type p53 gene or a temperature-sensitive mutant of p53. All cell lines had readily detectable telomerase activity regardless of p53 status. In addition, murine fibroblast cell strains established from tissues of p53+/+ and p53-/- (p53 knockout) mice expressed telomerase regardless of the p53 status of their tissue of origin. Levels of telomerase subunit mRNA (hEST2) were comparable among cell lines and tissues with different p53 status. These results imply that p53 status is not associated with telomerase activity per se and that activation of telomerase can occur either in cells completely devoid of p53 or in cells that have functional p53.

Animals↗
PubMed1998

An animal model to study erythrocyte senescence with a narrow time window of erythrocyte production.

Using the method of inducing spherocytic anemia in the rabbit with antibody serum, we have developed an animal model in which red blood cells (RBCs) can nearly grow synchronously. With this model, we determined that the surface charge density on the RBC membrane decreased with cell aging. The change was not linear, being much more profound in the latter half of RBC life span. There was a positive correlation between the mean RBC density and its "age" (r = 0.847, p < 0.01). However, the density distribution of the RBCs at the same "age" showed a broad range, and the density values for RBC groups with different ages showed considerable overlap. This indicates that the density gradient technique can be used to separate RBC population into fractions with different mean ages, but has a low resolving power for obtaining individual RBCs of a given "age".

Anemia↗
PubMed1998

Simultaneous loss of expression of syndecan-1 and E-cadherin in the embryonic palate during epithelial-mesenchymal transformation.

Epithelial-mesenchymal transformation (EMT) is the key mechanism for fusion and confluence of the rodent palate. During this process, medial edge epithelia (MEE) form a midline seam that subsequently transforms to mesenchymal cells. We studied syndecan-1 and E-cadherin, two molecules which have been shown to promote the epithelial phenotype, to determine their fate during palatal EMT. We found that both syndecan-1 and E-cadherin are expressed on basolateral surfaces of the MEE at day 14. Twelve hours later, when a midline seam has formed, syndecan-1 and E-cadherin are still present on its basal and lateral epithelial surfaces and they persist after the seam breaks up into epithelial islands. Then, expression of both molecules is lost simultaneously and abruptly when EMT occurs. On the contrary, previous in vitro studies of cell lines transfected with antisense cDNAs suggested that loss of syndecan-1 would lead to loss of E-cadherin or vice versa. We conclude that in vivo, synthesis of both E-cadherin and syndecan-1 is downregulated synchronously by the initiation of EMT, leading to an effective and correctly timed conversion of the epithelial cells to mesenchyme.

Animals↗
PubMed1998

Wild-type p53 and a p53 temperature-sensitive mutant suppress human soft tissue sarcoma by enhancing cell cycle control.

Soft-tissue sarcomas are a heterogeneous group of tumors that are putatively mesenchymal in origin. Therapeutic advances in this disease have been limited over the past several decades. Approximately one-half of all patients will ultimately succumb, usually to uncontrollable pulmonary metastases. Although little is known about the underlying molecular determinants driving soft-tissue sarcoma inception, proliferation, and metastasis, mutation of the p53 gene is the most frequently detected molecular alteration in this disease. Accordingly, we were interested in determining whether transduction of wild-type (wt) p53 into soft-tissue sarcomas bearing mutated p53 genes might alter the malignant phenotype. SKLMS-1 is a human-derived leiomyosarcoma cell line with a codon 245 p53 point mutation. Cationic liposome was used to transfect wt p53 or 143Ala temperature-sensitive mutant p53 into this cell line. SKLMS-1 stable transfectants expressing wt p53 had decreased cell proliferation in vitro, decreased in vitro colony formation in soft agar, and decreased tumorigenicity in severe combined immunodeficient mice in vivo. Flow cytometric analysis of cell cycle components demonstrated markedly increased G1 cell cycle arrest and decreased entry into S phase, which corresponded to the induction of p21cip1 protein in the transfectants. Using SKLMS-1 stable transfectants expressing the 143Ala p53 temperature-sensitive mutant, we demonstrated the kinetics of and the causal relationship between wt p53 expression, the wt p53-dependent induction of cell cycle inhibitor p21cip1, and inhibition of cell cycle progression in p53-transfected SKLMS-1 cells. The ability to restore wt p53 growth-regulatory functions in soft-tissue sarcoma may ultimately be useful as a future therapy in patients with soft-tissue sarcomas.

Animals↗
PubMed1998

In vivo cyclin E expression as a marker for early cervical neoplasia.

Identification of human papillomavirus (HPV)-related early cervical neoplasia and its distinction from benign epithelial alterations is based on either subjectively applied morphologic criteria or on identification of associated papillomaviruses. The direct and indirect consequences of HPV infection, however, potentially include upregulation of some host genes. We investigated one candidate, cyclin E, as a possible marker for HPV-related early squamous lesions. Serial paraffin sections from 92 archival cervical biopsy specimens were analyzed, including 19 non-neoplastic biopsy specimens, 30 low-grade and 31 high-grade squamous intraepithelial lesions (SILs), and 12 invasive carcinomas. Four parameters (histologic diagnosis, cyclin E staining, HPV status and, in selected cases, Ki-67 staining) were scored, and their relationship(s) were evaluated by the chi2 independence test. Twenty-one, 73, 79, and 75% of nonlesional epithelia, low-grade SILs, high-grade SILs, and invasive squamous cell carcinomas, respectively, were HPV positive (P < .001 for HPV status vs. diagnosis). Cyclin E staining was nuclear in distribution, and the frequency of positive staining, ie., moderate or strong intensity, was significantly higher (P < .001 for cyclin E staining vs. diagnosis) in all of the lesional epithelia (92.3, 51.6, and 50% of low-grade and high-grade SILs and carcinomas, respectively) compared with nonlesional epithelium (5.9%). Cyclin E positivity and/or HPV positivity was seen in 100% of the low-grade SILs. Epithelial Ki-67 and cyclin E staining were strikingly different in frequency and distribution. Cyclin E was undetectable in basal cells of normal mucosa (which were positive for Ki-67) and limited to suprabasal epithelium in noninvasive lesions. Cyclin E expression correlates strongly with morphologic features of HPV-related preinvasive and invasive cervical disease. This correlation is most pronounced in low-grade SILs. The possibility that in vivo cyclin E staining is a generic marker for HPV infection in low-grade SILs merits additional study.

Biomarkers, Tumor↗
PubMed1998

Early adolescents' perceptions of cigarette smoking: a cross-sectional survey in a junior high school.

Most adult cigarette smokers start smoking during adolescence. Since youths' perceptions of cigarette smoking may influence their decision to smoke, it is important to understand early adolescents' feelings about, and information sources regarding, smoking. In the present study, a cross-sectional survey, conducted in an urban junior high school, asked students in grades six to eight about their attitudes toward cigarette advertising, their perception of the harmful effects of cigarette smoking, and their sources of information. One hundred students completed the questionnaire, 12 of whom were current or former smokers. Approximately 27% believed cigarette advertising significantly influenced their classmates or themselves. Ninety percent recognized that cigarette smoking was seriously harmful. The source of this information was mainly teachers and parents. While 53% of the students identified their parents as the ones who taught them not to smoke, 47.8% of these parents were smokers themselves. Only 2% of the students indicated that they received information about the effects of smoking from health providers.

Adolescent↗
PubMed1997

Development of decompensated dilated cardiomyopathy is associated with decreased gene expression and activity of the milrinone-sensitive cAMP phosphodiesterase PDE3A.

BACKGROUND: Phosphodiesterase III (PDE3) inhibitors are inotropic agents used to treat congestive heart failure (CHF) and are less effective in patients with severe CHF. Little is known about relative changes in PDE3 activity or gene expression during the evolution of cardiomyopathy. METHODS AND RESULTS: In the present study, we evaluated temporal changes in PDE3A gene expression before and after pacing-induced CHF in nine mongrel dogs. Three weeks of left ventricular (LV) pacing produced LV end-diastolic pressures of 15+/-1.7 mm Hg, whereas overt CHF at 4 to 5 weeks was associated with LV end-diastolic pressures of 24+/-1.7 mm Hg; prepacing values were 6.6+/-0.6 mm Hg. Total RNA isolated from LV tissues was analyzed on Northern blots; 10 unpaced normal hearts served as tissue controls. Signals for PDE3A mRNAs (7, 8, and 10 kb) or PDE4D (7.6 kb) were normalized against glyceraldehyde-3-phosphate dehydrogenase (GAPDH) or ribosomal 18S RNA. Before the onset of CHF, PDE3A/GAPDH ratios were not different between the control and 3-week paced groups. In contrast, all PDE3A/GAPDH ratios were selectively reduced by 52%, and PDE3A/18S was reduced by 70% (P<.05) in CHF; PDE4D/GAPDH (or 18S) was unchanged. LV tissues from four control and four CHF dogs were also processed to isolate cytosolic and microsomal membrane protein for cAMP PDE3 activity assays. CHF was associated with a significant 54% reduction (P<.05) in microsomal but not cytosolic PDE3 activity. CONCLUSIONS: Selective downregulation of PDE3A may account in part for the ineffectiveness of milrinone in the treatment of severe CHF.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1997

Cross-reactivity of C219 anti-p170(mdr-1) antibody with p185(c-erbB2) in breast cancer cells: cautions on evaluating p170(mdr-1)

BACKGROUND: Increased expression of the multidrug resistance gene (MDR-1)-encoded P-glycoprotein (p170[mdr-1]) is a major cause of tumor cell multidrug resistance. p170(mdr-1) functions as a drug-efflux pump to reduce the cellular accumulation of specific drugs. MDA-MB-435 human breast cancer cells that have been transfected with oncogene c-erbB2 complementary DNA (435.eb cells) express high levels of the transmembrane glycoprotein p185(c-erbB2) and exhibit increased resistance to the chemotherapeutic agent paclitaxel via p170(mdr-1)-independent mechanisms. We have recently discovered that the widely used monoclonal antibody C219, which is specific for p170(mdr-1), may cross-react with p185(c-erbB2) in 435.eb cells. In this study, we have investigated the nature of this cross-reactivity. METHODS: Immunoprecipitation experiments involving the use of breast cancer cells that express different levels of p185(c-erbB2) were performed, and C219 was used for western blot analysis of immunoprecipitated proteins. Immunohistochemical analyses were performed on acetone-fixed slides of human breast cancer cells. Peptide sequence comparisons and enzyme-linked immunosorbent assays were performed to determine the molecular basis of C219 cross-reactivity with p185(c-erbB2). RESULTS: The cross-reactivity of C219 with p185(c-erbB2) was demonstrated by both western blot and immunohistochemical analyses. Peptide sequence comparisons revealed that C219 recognizes an epitope in p170(mdr-1) (C219 epitope) that shares sequence homology with p185(c-erbB2). Enzyme-linked immunosorbent assays demonstrated that C219 recognizes synthetic peptides derived from both the C219 epitope in p170(mdr-1) and the C219 epitope-homologous region in p185(c-erbB2). CONCLUSIONS: The anti-p170(mdr-1) monoclonal antibody C219 cross-reacts with p185(c-erbB2) through a peptide sequence in p185(c-erbB2) that is homologous to the C219 epitope in p170(mdr-1).

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Quantitative assessment of myelin basic protein-reactive T cell entry to the central nervous system by using oligonucleotide probes complementary to VDJ junctional sequences of rat TCR beta-chain.

The VDJ junctional region represents the most diverse part of the antigenic TCR. We have previously reported that of 200 sequenced TCR beta-chains of rat MBP-reactive T cells, rarely did two share sequence homology over the entire CDR3 region. In this study, we demonstrate that sequences of the TCR CDR3 region are excellent clonotypic markers for rat MBP-reactive T cell clones and oligonucleotide probes complementary to the CDR3 region of three T cell clones specifically recognized the TCR from which they were derived, but failed to recognize syngeneic T cells that express a similar TCR beta-chain or T cells that share both V beta and J beta usage. To explore this observation, we determined the ability of MBP-reactive T cell clones to enter the CNS. We were able to show that some MBP-reactive T cell clones have an augmented ability to enter the CNS and that fully-activated T cells have a higher penetrating activity than their less-activated T cell counterparts.

Amino Acid Sequence↗
PubMed1997

Identification of a new P-glycoprotein-like ATP-binding cassette transporter gene that is overexpressed during hepatocarcinogenesis.

The liver is remarkably insensitive to a variety of cytotoxins and expresses a number of known drug resistance genes. To isolate new P-glycoprotein (Pgp)-related genes, we screened a normal rat liver cDNA library at low stringency with a MDR1 cDNA fragment containing the P-loop and ATP binding site. We isolated a novel cDNA closely related to the Pgps that is dramatically increased in hepatic neoplasia and refer to it as P-glycoprotein-related protein (PRP). The predicted protein shows PRP to be a member of the ATP-Binding Cassette (ABC) family of proteins, and a multisequence comparison of the nucleotide binding domain and the ABC family signature sequences reveals that PRP sequences are highly conserved with the greatest similarity to the yeast heavy metal transporter encoded by hmtl. However, the hydropathy plot analysis suggests that PRP does not have any prominent membrane-spanning domains and thus is not typical of ABC transporters. The PRP transcript is detected in many normal tissues. In the H35 hepatoma cell line, PRP was overexpressed compared to normal liver. Southern blot analysis of DNA from the H35 rat hepatoma cells reveals that the PRP gene was amplified compared to normal liver. The orotic acid model of hepatocarcinogenesis was used to determine if during stepwise progression to liver cancer, PRP changed with hepatocarcinogenesis. At the hyperplastic nodule stage, PRP expression was increased over its expression in normal surrounding liver. More dramatic increases in PRP expression were found in frank hepatic carcinomas. Cumulatively, these studies are the first to link a novel ABC family member to the hepatic neoplastic process, a role that may be recapitulated in other cells, considering the ubiquitous expression of PRP.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Increased sarcolemmal glucose transporter abundance in myocardial ischemia.

Many clinical and laboratory studies suggest that an increase in glucose uptake and metabolism by ischemic myocardium helps protect myocardial cells from irreversible injury. We have examined whether increased sarcolemmal abundance of cardiomyocyte glucose transporters plays a role in this adaptive response. We have shown that acute myocardial ischemia in perfused rat hearts results in increased sarcolemmal abundance of the major glucose transporter, GLUT4, by causing translocation of GLUT4 molecules from an intracellular compartment to the sarcolemma. In nonischemic control hearts only 18 +/- 2.8% of GLUT4 molecules were on the sarcolemma whereas in ischemic hearts this increased to 41 +/- 9.3%. Insulin also caused translocation of GLUT4 molecules to the sarcolemma, and resulted in 61 +/- 2.6% of GLUT4 molecules on the sarcolemma. The combination of ischemia and insulin did not result in additive increases in sarcolemmal GLUT4 abundance. In more persistent or chronic ischemia, the other major myocardial glucose transporter, GLUT1, appears to play an important role. The mRNA for this transporter, which is constitutively expressed on cardiomyocyte sarcolemma, was increased 2.0-fold in regions of hibernating myocardium in humans with coronary heart disease as well as in persistently hypoxic rat neonatal cardiomyocytes in primary culture. In neither of these conditions was GLUT4 mRNA expression increased. Thus, acute myocardial ischemia increases sarcolemmal glucose transporter abundance mainly by translocating previously synthesized GLUT4 molecules from an intracellular compartment, whereas more chronic ischemia also increases GLUT1 abundance via enhanced mRNA expression. Increased GLUT1 and GLUT4 abundance may participate in the augmented glucose uptake of ischemic myocardium and therefore may help protect ischemic myocardium from irreversible injury.

Animals↗