Biomedical subjects

S Li

Publications and source records attributed to S Li.

At least 289 records · Page 16Linked to original sources

PubMed2001

Decreased expression of Wnt7a mRNA is inversely associated with the expression of estrogen receptor-alpha in human uterine leiomyoma.

Wnt-7a gene not only guides the development of the anterior-posterior axis in the female reproductive tract, but also plays a critical role in uterine smooth muscle pattering and maintenance of adult uterine function. This gene is also responsive to changes in the levels of sex steroid hormone in the female reproductive tract. To explore the molecular mechanisms underlying the pathogenesis of uterine leiomyoma, the expression of Wnt7a mRNA in the leiomyoma has been assessed. RT-PCR was performed on uterine leiomyomas and the adjacent myometria. Of 30 cases of leiomyomas studied, 67% showed a decreased mRNA level as compared to the paired myometria. On the other hand, estrogen receptor-alpha (ER-alpha) mRNA is hyper-expressed in 67% of the leiomyomas as compared to their paired myometrium. An inverse association at mRNA expression was found between Wnt7a and ER-alpha. Miller et alhas shown that fetal exposure of DES results in de-regulation of Wnt7a during uterine morphogenesis. Referring to their results, we have postulated that hypersensitivity of leiomyoma cells to estrogen may deregulate the Wnt7a expression. Decreased expression of Wnt7a may lead to loss of control in patterning of the myometrium and result in development of leiomyoma

Estrogen Receptor alpha↗

PubMed2001

Phytochemical glyceollins, isolated from soy, mediate antihormonal effects through estrogen receptor alpha and beta.

The flavonoid family of phytochemicals, particularly those derived from soy, has received attention regarding their estrogenic activity as well as their effects on human health and disease. In addition to these flavonoids other phytochemicals, including phytostilbene, enterolactone, and lignans, possess endocrine activity. The types and amounts of these compounds in soy and other plants are controlled by both constitutive expression and stress-induced biosynthesis. The health benefits of soy-based foods may, therefore, be dependent upon the amounts of the various hormonally active phytochemicals within these foods. The aim was to identify unique soy phytochemicals that had not been previously assessed for estrogenic or antiestrogenic activity. Here we describe increased biosynthesis of the isoflavonoid phytoalexin compounds, glyceollins, in soy plants grown under stressed conditions. In contrast to the observed estrogenic effects of coumestrol, daidzein, and genistein, we observed a marked antiestrogenic effect of glyceollins on ER signaling, which correlated with a comparable suppression of 17 beta-estradiol-induced proliferation in MCF-7 cells. Further evaluation revealed greater antagonism toward ER alpha than ER beta in transiently transfected HEK 293 cells. Competition binding assays revealed a greater affinity of glyceollins for ER alpha vs. ER beta, which correlated to greater suppression of ER alpha signaling with higher concentrations of glyceollins. In conclusion, we describe the phytoalexin compounds known as glyceollins, which exhibit unique antagonistic effects on ER in both HEK 293 and MCF-7 cells. The glyceollins as well as other phytoalexin compounds may represent an important component of the health effects of soy-based foods.

Benzopyrans↗

PubMed2001

Organized sports for children and preadolescents.

Participation in organized sports provides an opportunity for young people to increase their physical activity and develop physical and social skills. However, when the demands and expectations of organized sports exceed the maturation and readiness of the participant, the positive aspects of participation can be negated. The nature of parental or adult involvement can also influence the degree to which participation in organized sports is a positive experience for preadolescents. This updates a previous policy statement on athletics for preadolescents and incorporates guidelines for sports participation for preschool children. Recommendations are offered on how pediatricians can help determine a child's readiness to participate, how risks can be minimized, and how child-oriented goals can be maximized.

Age Factors↗

PubMed2001

Immunoelectron microscopic localization of 3beta-hydroxysteroid dehydrogenase and type 5 17beta-hydroxysteroid dehydrogenase in the human prostate and mammary gland.

The subcellular distribution of steroidogenic enzymes has so far been studied mostly in classical endocrine glands and in the placenta. In the peripheral intracrine organs which synthesize sex steroids there is no indication about the organelles which contain the enzymes involved in steroid biosynthesis. We have thus investigated the subcellular localization of two enzymes involved in the production of sex steroids, namely 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and type 5 17beta-hydroxysteroid dehydrogenase (17beta-HSD). Using specific antibodies to these enzymes, we conducted immunoelectron microscopic studies in two peripheral tissues, namely the human prostate and mammary gland. In the prostate, immunolabelling for both 3beta-HSD and type 5 17beta-HSD was detected in the basal cells of the tube-alveoli as well as in fibroblasts and endothelial cells lining the blood vessels. In all the labelled cell types, the gold particles were distributed throughout the cytoplasm. No obvious association with any specific organelle could be observed, although some concentration of gold particles was occasionally found over bundles of microfilaments. In mammary gland sections immunolabelled for 3beta-HSD or type 5 17beta-HSD localization, labelling was observed in the cytoplasm of the secretory epithelial cells in both the acini and terminal ducts. Immunolabelling was also found in the endothelial cells as well as in fibroblasts in stroma and blood vessels. The gold particles were not detected over any organelles, except with the occasional accumulation of gold particles over microfilaments. The present data on the localization of two steroidogenic enzymes leading to the synthesis of testosterone indicate that these enzymes are located not only in epithelial cells but also in stromal and endothelial cells in both tissues studied. The absence of any association of the enzymes with membrane-bound organelles appears as a common finding in the reactive cell types of two peripheral tissues.

3-Hydroxysteroid Dehydrogenases↗

PubMed2001

Immunoelectron microscopic localization of three key steroidogenic enzymes (cytochrome P450(scc), 3 beta-hydroxysteroid dehydrogenase and cytochrome P450(c17)) in rat adrenal cortex and gonads.

The biosynthesis of steroid hormones in endocrine steroid-secreting glands results from a series of successive steps involving both cytochrome P450 enzymes, which are mixed-function oxidases, and steroid dehydrogenases. So far, the subcellular distribution of steroidogenic enzymes has been mostly studied following subcellular fractionation, performed in placenta and adrenal cortex. In order to determine in situ the intracellular distribution of some steroidogenic enzymes, we have investigated the ultrastructural localization of the three key enzymes: P450 side chain cleavage (scc) which converts cholesterol to pregnenolone; 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) which catalyzes the conversion of 3 beta-hydroxy-5-ene steroids to 3-oxo-4-ene steroids (progesterone and androstenedione); and P450(c17) which is responsible for the transformation of C(21) into C(19) steroids (dehydroepiandrosterone and androstenedione). Immunogold labeling was used to localize the enzymes in rat adrenal cortex and gonads. The tissues were fixed in 1% glutaraldehyde and 3% paraformaldehyde and included in LR gold resin. In the adrenal cortex, both P450(scc) and 3 beta-HSD immunoreactivities were detected in the reticular, fascicular and glomerular zones. P450(scc) was exclusively found in large mitochondria. In contrast, 3 beta-HSD antigenic sites were mostly observed in the endoplasmic reticulum (ER) with some gold particles overlying crista and outer membranes of the mitochondria. P450(c17) could not be detected in adrenocortical cells. In the testis, the three enzymes were only found in Leydig cells. Immunolabeling for P450(scc) and 3 beta-HSD was restricted to mitochondria, while P450(c17) immunoreactivity was exclusively observed in ER. In the ovary, P450(scc) and 3 beta-HSD immunoreactivities were found in granulosa, theca interna and corpus luteum cells. The subcellular localization of the two enzymes was very similar to that observed in adrenocortical cells. P450(c17) could also be detected in theca interna cells of large developing and mature follicles. As observed in Leydig cells, P450(c17) immunolabeling could only be found in the ER. These results indicate that in different endocrine steroid-secreting cells P450(scc), 3 beta-HSD and P450(c17) have the same association with cytoplasmic organelles (with the exception of 3 beta-HSD in Leydig cells), suggesting similar intracellular pathways for biosynthesis of steroid hormones.

3-Hydroxysteroid Dehydrogenases↗

PubMed2001

Dislodgment of polyethylene liners in first and second-generation Harris-Galante acetabular components. A report of eighteen cases.

BACKGROUND: Dislodgment of the polyethylene liner is an increasingly common complication following total hip arthroplasty. The purposes of this study are to present the results in a series of patients with this complication and to analyze the mode of failure. METHODS: Between November 1995 and January 2001, eighteen patients who had had a total hip arthroplasty presented with dislodgment of the polyethylene liner from a Harris-Galante metal acetabular shell. The medical records, radiographs, operative notes, and retrieved components were reviewed. In addition, scanning electron microscopy was used to study the fractured surfaces in a shell that had four broken tines. RESULTS: The components had been in situ for an average of seven years (range, three to eleven years). Seventeen components were second generation, and one was first generation. Symptoms developed spontaneously in sixteen patients, during sexual intercourse in one, and following a fall on the hip in one. Radiographs showed eccentric positioning of the head in all of the hips and broken tines in six. All of the shells were well fixed. Treatment consisted of revision of the shell in four patients, exchange of the liner in four, cementation of a new liner into the shell in seven, and cementation of an all-polyethylene cup in three. The liners had severe damage of the rim. Scanning-electron microscopy of the fractured surfaces of four tines revealed a fatigue pattern. CONCLUSIONS: We believe that, as the liner wears and becomes loose because of an inadequate locking mechanism, progressive micromotion occurs and the load increases on the polyethylene rim until it deforms and/or fractures. Subsequently, nothing prevents the liner from rotating out of the shell. As this mechanism of failure appears to include fatigue failure of the locking tines and wear of the liner, this complication is likely to increase as the components age in situ.

Acetabulum↗

PubMed2001

Nonviral gene therapy.

The last 10 years have seen substantial progress in the development and application of nonviral vectors in gene therapy. Several novel nonviral methods have been developed that approach viruses with respect to transfection efficiency. A variety of nonviral delivery systems that can be used for gene therapy in different clinical settings are also available. In this review article, we will detail all of the major nonviral vectors that are currently used in gene therapy while highlighting some recent developments, particularly the progress towards the understanding of the cellular and in vivo barriers in gene transfer. Recent advancement in achieving sustained and regulated gene expression will also be addressed. Finally, this review will briefly cover targeted gene repair using nonviral delivery systems. Their impact in gene therapy will also be discussed.

Adjuvants, Immunologic↗

PubMed2001

How close is too close? A comparison of proxemic reactions of Singaporean Chinese to male intruders of four ethnicities.

Cultural and ethnic influence on proxemic behavior and invasions of personal space were investigated. 173 Chinese Singaporean undergraduates rated minimum interpersonal distance for perceived male intruders from four ethnic groups in Singapore--Malay, Indian, Chinese, and Caucasian. Rated distance scores ranked from "most distant" Indian Chinese dyads decreasing (in order of minimum distance) through Malay-Chinese. Caucasian-Chinese, and Chinese-Chinese dyads, independent of sex.

Adult↗

PubMed2001

Primary Epstein-Barr virus-associated Hodgkin disease of the ileum complicating Crohn disease.

We describe a case of primary Hodgkin disease of the terminal ileum in a 38-year-old man with Crohn disease of 24 years' duration. The infiltrate was located in an ulcerated fistula involving the terminal ileum and urinary bladder. Reed-Sternberg cells and their variants were characteristically positive for CD15, fascin, and CD30 and showed focal positivity for CD20. Epstein-Barr virus messenger RNA was also detected in the neoplastic cells. Staging revealed no evidence of other lymph node or organ involvement. Although rare, primary gastrointestinal Hodgkin disease arising in the setting of Crohn disease may have a stronger association with Epstein-Barr virus infection than conventional Hodgkin disease.

Adult↗

PubMed2001

CD79a(+) T-cell lymphoblastic lymphoma with coexisting Langerhans cell histiocytosis.

Although there is a close association between Langerhans cell histiocytosis and malignant neoplasms, simultaneous occurrence of lymphoblastic lymphoma and Langerhans cell histiocytosis in the same lymph node is an extremely rare finding. Herein, we describe such a case in a 26-year-old woman who presented with progressive cervical lymphadenopathy. The lymphoma cells have an immature T-cell phenotype (terminal deoxynucleotidyl transferase(+), HLA-DR(+), CD34(+), CD38(+), and CD7(+)) with expression of both CD3 and CD79a on immunohistochemical stain. The Langerhans cells are present focally with the characteristic morphologic features and immunophenotype (CD1a(+) and S100(+)). The significance of CD79a coexpression in T-cell lymphoblastic lymphoma and the association between lymphoblastic lymphoma and Langerhans cell histiocytosis are discussed.

Adult↗

PubMed2001

Pluronic P85 enhances the delivery of digoxin to the brain: in vitro and in vivo studies.

Drug delivery across the blood-brain barrier is limited by several mechanisms. One important mechanism is drug efflux, mediated by several transport proteins, including P-glycoprotein. The goal of this work was to examine the effect of a novel drug delivery system, Pluronic block copolymer P85, on P-glycoprotein-mediated efflux from the brain using in vitro and in vivo methods. The hypothesis was that specific Pluronic copolymer systems enhance drug delivery to the central nervous system through the inhibition of P-glycoprotein. The effect of P85 on the cellular accumulation and transport of digoxin, a model P-glycoprotein substrate, was examined in porcine kidney epithelial cells (LLC-PK1) transfected with the human MDR1 gene. The effect of P85 on the directional flux across an in vitro BBB was also characterized. In vivo brain distribution studies were accomplished using wild-type and P-glycoprotein knockout mice. Pluronic increased the cellular accumulation of digoxin 3-fold in LLC-PK1 cells and 5-fold in the LLC-PK1-MDR1-transfected cells. Similar effects were observed for a prototypical P-glycoprotein substrate rhodamine-123. P85 treatment decreased the basolateral-to-apical and increased the apical-to-basolateral digoxin flux across LLC-PK1-MDR1 cell monolayers, and analogous results were observed with the in vitro BBB monolayers. The coadministration of 1% P85 with radiolabeled digoxin in wild-type mice increased the brain penetration of digoxin 3-fold and the digoxin level in the P85-treated wild-type mice was similar to that observed in the P-glycoprotein-deficient animals. These data indicate that Pluronic P85 can enhance the delivery of digoxin to the brain through the inhibition of the P-glycoprotein-mediated efflux mechanism.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

Factors associated with perceived risk in automotive employees at increased risk of colorectal cancer.

Risk perception may be an important motivator of health-related behaviors. To develop effective risk communication messages, it is important to understand both the patterns of association between perceived risk and health-related behaviors as well as the correlates of risk perception. Very little is known about whether correlates of risk perception are similar in cross-sectional data compared with prospective data. Furthermore, there are scant data on consistency of correlates of risk perception across groups who vary in objective medical risk. If correlates differ, it would underscore the need to tailor intervention messages based on subgroup characteristics as well as increase awareness of the limitations of basing intervention messages only on cross-sectional data. We analyzed data on a subset of 5042 employees who participated in The Next Step Trial, a randomized health promotion trial to encourage colorectal cancer screening and dietary change. We restricted our analysis to only those automotive workers who were white, male, and did not have colorectal cancer (4477/5042) and who returned surveys both at baseline (2,684/4,477) and at year 2 of follow-up (1955/2684). Initial analyses detected interactions between a history of polyps and several of the other covariates. Therefore, univariate and multivariable analyses were conducted separately for men with and without a personal history of colorectal polyps. Within each of the four subgroups (those with or without polyps in the baseline or follow-up analyses), we examined associations between perceived risk measured at baseline (cross-sectional analyses) and at year 2 of follow-up (prospective analyses) in relation to intervention group status, demographic, medical history, psychosocial, and worksite characteristics measured at baseline. To assess the predictive ability of the models, we computed sensitivity and specificity as measures of each model's ability to correctly classify men into their respective subgroup. Although there was no association between perceived risk and intervention group status in the four subgroups analyzed, we included intervention group status as a covariate in all analyses. At baseline (cross-sectional analyses) among men with and without a history of polyps, perceived risk was positively associated with family history of colorectal polyps or cancer, family support for screening, and worry about being diagnosed with colorectal cancer. In addition, for men without polyps, perceived risk was positively associated with being a current smoker. At year 2 of follow-up (prospective analyses) for men with and without polyps, perceived risk at year 2 was positively associated with family history and baseline perceived risk and was negatively associated with having a normal screening examination or no examinations during the trial. In addition, for men with polyps, perceived risk was positively associated with belief in the salience and coherence of screening and with intention to be screened and was negatively associated with access to screening at the worksite. Specificity was higher than sensitivity in three of four subgroups and was >65% in all subgroups. Except for family history, messages to influence perceived risk would emphasize different factors, depending on whether associations were based on baseline or follow-up data and depending on whether men reported a personal history of polyps. For example, although intervention messages using baseline data would emphasize the same factors for men with or without polyps, messages based on follow-up data would emphasize psychosocial characteristics, such as salience and coherence of screening and intention for men with a history of polyps but not for men without. Our findings support the need to delineate subgroups in the study population to target and tailor health-related messages based on respondent characteristics. Our findings also underscore the need to base health-related messages on prospective data as well as cross-sectional data to better address health-related beliefs and behaviors.

Adult↗

PubMed2001

[CYP11B2 expression in rat liver and the efficacy of antisterone on liver fibrosis].

OBJECTIVE: To identify aldosterone synthase gene-CYP11B2 mRNA expression in rat livers and evaluate the efficacy of antisterone. METHODS: One hundred and twenty male Wistar rats were divided into 3 groups: model group (subcutaneous injection of CCl(4), 0.25 ml/100 mg, 3 times/week), antisterone group (besides same dosage of CCl(4) given, gastropufusion of antisterone of 20mg x kg(-1) x d(-1)), and control group (subcutaneous injection of olive oil). The area of collagen was examined by image analyzing system. The expression of aldosterone synthase gene-CYP11B2 mRNA was detected by RT-PCR and in situ hybridization. RESULTS: The expression of CYP11B2 mRNA, which located in the endoplasm of HSC, was upregulated when fibrogenesis occurred. The grade of fibrosis and the area of collagen in antisterone group were less than those in model group before 6th week (P<0.05). After the 6th week however, there was no significant difference between the two groups (P>0.05). CONCLUSIONS: The expression of CYP11B2 mRNA is upregulated in fibrotic liver. Antisterone can partly have a fibrogenesis-inhibiting effect on the early stage of CCl(4)-induced hepatic fibrosis.

Animals↗

PubMed2001

[Lipopolysaccharide upregulates expression of CD14 gene and CD14 proteins of hepatocytes in rats].

OBJECTIVE: To observe the expression of CD14 mRNA and its protein in rat hepatocytes during endotoxemia. METHODS: The acute endotoxemia model of wistar rats was established by injection of a dose of LPS (5mg/kg, Escherichia coli O111:B4) via the tail vein, then the rats were sacrificed at 3, 6, 12, and 24 hour, respectively. Hepatocytes were isolated from normal and LPS-injected rats by in situ collagenase perfusion technique. Hepatocytes and hepatic tissue were collected to measure the expression of CD14 mRNA and CD14 protein by reverse transcriptase-polymerase chain reaction (RT-PCR) or Western blot analysis. The binding of fluorescein isothiocyanate (FITC)-CD14 polyclone antibody to isolated hepatocytes was also assessed by flow cytometric analysis (FCM). RESULTS: In the rats with endotoxemia, the expression of CD14 mRNA and CD14 protein in hepatic tissue and isolated hepatocytes were stronger at 6, 12 and 24 hour than that in control rats (P<0.01). FCM showed that positive cell numbers of FITC-CD14 in the rats with endotoxemia increased when compared with normal control group (P<0.01). CONCLUSIONS: LPS can markedly upregulate the expression of CD14 mRNA and CD14 proteins in hepatic tissue and isolated hepatocytes.

Animals↗

PubMed2001

Suicide in Travis County, Texas, from 1994 through 1998.

Suicide, the ninth leading cause of death in the United States, has not been adequately studied in Travis County, Texas. To describe the occurrence of completed suicide in Travis County, 426 cases of completed suicide from 1994 through 1998 were collected and the data were analyzed with the chi 2 test and the t test. The annual suicide rate in Travis County is 13.0 per 100,000. Caucasian males have the highest annual suicide rate among all races, followed by Hispanics and, then, blacks. The highest suicide rate was seen in persons aged 75 years and older. The second most frequent rate was for those aged 45 through 54 years. Guns are the most common means of suicide in both males and females (60.8% and 37.3%, respectively). A person who is Caucasian, male, and aged 75 years and older is at the highest risk. Reducing the availability of firearms may have a significant impact on the suicide rates in Travis County.

Adolescent↗

PubMed2001

Effects of morphological patterning on endothelial cell migration.

The migration of vascular endothelial cells (ECs) plays an important role in vascular remodeling. Here we studied the effects of cell morphology on the migration of bovine aortic ECs by culturing cells on micropatterned strips of collagen matrix (60-, 30-, and 15-microm wide). The spreading areas of the cells on 15- and 30-microm wide strips were 30% lower than those on 60-microm wide strips and unpatterned collagen. The cells on 15-microm wide strips completely aligned in the direction of the strip, and had significantly lower shape index than those in all other groups. On strips of all widths, ECs tended to migrate in the direction of strips. ECs on 15-microm wide strips had highest speed, particularly in the direction of the strip. Vinculin staining showed that the leading edge of ECs on 15-microm wide strips had focal adhesions that were oriented with their lamellipodial protrusion and the direction of cell migration; this arrangement of the focal adhesions may promote EC migration. The present study provides direct evidence on the role of cell morphology in EC migration, and will help us to understand the mechanisms of EC migration during angiogenesis and wound healing.

Animals↗

PubMed2001

Triterpenoids and other compounds from Salvia roborowskii Maxim.

Two new triterpenoids, 2 alpha-hydroxy-3 beta-methoxyurs-12-en-28-oic acid and 3 alpha-hydroxy-2 alpha-methoxyurs-12-en-28-oic acid as well as 25 known compounds were isolated from the whole plant of Salvia roborowskii Maxim. Their structures were elucidated by means of spectral data and chemical transformation. This is the first report on the chemical constituents of this plant. The presence of eugenyl beta-D-glucopyranoside 22 in a plant of the genus Salvia is also reported for the first time.

Acetylation↗

PubMed2001

[Experimental and mechanism analyses on HCl emission control during PVC combustion in fixed beds].

Incineration of chloridated plastic (PVC) in solid wastes contributes much to HCl pollutant in air environment. The characteristics of HCl emissions and reduction during PVC combustion were conducted in a nearly isothermal, externally heated, horizontal quartz-tube reactor. With increasing temperature from 700 to 900 degrees C, the conversion of HCl increased leniently from 82.5% to 88.3%. High excess air factor enhanced a small amount of HCl existing in form of Cl2. The calcium-based sorbents including CaCO3, Ca(OH)2, Ca(CH3COO)2 exhibited high HCl capture efficiencies from 68% to 79%, while magnesium-based sorbent less than that of 3%. Influences of operational variables, i.e., size of sorbent, Ca/Cl molar ratio and combustion fume compositions, on the HCl reduction were discussed. From a point of view of equilibrium constant of dechloridization reaction the experimental results were explained in detail.

Hot Temperature↗