11 resultados para surfactants and spreading
em DigitalCommons@The Texas Medical Center
Resumo:
Purpose. To evaluate the effectiveness of a culturally sensitive educational intervention that used an African American lay survivor of breast cancer to increase knowledge of breast cancer, decrease cancer fatalism, and increase participation in mobile mammography screening among African American women. ^ Design. Experimental pretest/posttest design. ^ Setting. Two predominantly African American churches in a large southwestern metropolitan city. ^ Sample. Participants included 93 African American women, 40 years of age and older. Participants were randomly assigned to an intervention group (n = 48) or a control group (n = 45). ^ Methods. Pretest and post-test measures included the Breast Cancer Knowledge Test and the Powe Fatalism Inventory. In addition, demographic and breast screening practices were collected by questionnaire. The intervention group received a breast cancer educational testimonial from an African American lay survivor of breast cancer, who answered questions and addressed concerns, while stressing the importance of taking responsibility for one's own health and spreading disease prevention messages throughout the African American community. The control group viewed the American Cancer Society “Keep In Touch” video prepared specifically for African American women. Participants in both groups were given culturally sensitive educational materials designed to increase knowledge about breast cancer, and were instructed on breast self-examination by an African American registered nurse, using ethnically appropriate breast models. In addition, after the post-test, all eligible participants were given an opportunity to have a free mammogram via a mobile mammography unit parked at the church. ^ Findings. Participants in the intervention group had a significant increase (p = .03) in knowledge of breast cancer and a significant decrease (p = .000) in fatalism scores compared to those individuals in the control group. The intervention group had a 61% participation rate in screening, while the control group had a 39% participation rate in screening. However, the difference was not statistically significant at the .05 level (p = .07). ^ Conclusions. Results demonstrate that culturally sensitive breast cancer education is successful in increasing knowledge and decreasing cancer fatalism. While there was a trend toward behavior change in the intervention group, more research needs to be done in this area. ^
Resumo:
In normal lymphocytes an “inside-out” signal up-regulating integrin adhesion is followed by a ligand mediated “outside-in” signal for cell spreading. Although PKC mediates both events, distinct roles were found for different PLCs. The inhibition of phosphatidylinositol specific PLC decreased both cell adhesion and spreading on fibronectin in T cell receptor/CD28 activated peripheral blood T cells. However, inhibition of phosphatidylcholine specific PLC only blocked cell spreading and did not affect adhesion, indicating that “inside-out” signaling for the integrin α4β1 proceeds through phosphatidylinositol specific PLC and PKC, while the “outside-in” signal utilizes phosphatidylcholine specific PLC and PKC. Furthermore, β1 integrin chain mediated morphological changes in the T lymphocytic cell line HPB-ALL directly paralleled PKA activation, treatment of these cells with an inhibitory anti-β1 antibody blocked PKA activation and cell spreading, and this inhibition could be overcome by activating adenylate cyclase. Furthermore, inhibition of PKA was found to decrease the overall strength of cell adhesion or cellular avidity without affecting individual receptor affinity for soluble ligand. ^ When HPB-ALL cells interact with immobilized FN, two separate morphological phenotypes can be induced. Some cells flattened their cell body into a triangular shape and begin to migrate, while others extended a pseudopod from their stationary cell body. This second morphology recapitulates the shape changes observed during transendothelial migration. During these morphological changes, α4β1 integrins are internalized into endocytic vesicles that ultimately accumulate at the juncture between the cell body and an extending pseudopod. From this juncture, they are rapidly transported down the length of the pseudopod to its most distal end. ^ In addition to an accumulation of integrin containing vesicles, the pseudopod base was found to have increased amounts of the small GTPase RhoA and active PKA. The inhibition of PKA or RhoA resulted in lymphocytes with similar aberrant stellate morphologies. Furthermore, inhibition of PKA blocked the α4β1 mediated phosphorylation of RhoA. The co-localization of active PKA, RhoA and integrin containing endocytic vesicles indicates that integrin triggering can cause the rapid redistribution and activation of key signaling intermediates and raises the possibility that regulation of lymphocyte morphology by PKA and RhoA is through adhesion receptor recycling. ^
Resumo:
Sexually transmitted infections (STIs) are a major public health problem, and controlling their spread is a priority. According to the World Health Organization (WHO), there are 340 million new cases of treatable STIs among 15–49 year olds that occur yearly around the world (1). Infection with STIs can lead to several complications such as pelvic inflammatory disorder (PID), cervical cancer, infertility, ectopic pregnancy, and even death (1). Additionally, STIs and associated complications are among the top disease types for which healthcare is sought in developing nations (1), and according to the UNAIDS report, there is a strong connection between STIs and the sexual spread of HIV infection (2). In fact, it is estimated that the presence of an untreated STI can increase the likelihood of contracting and spreading HIV by a factor up to 10 (2). In addition, developing countries are poorer in resources and lack inexpensive and precise diagnostic laboratory tests for STIs, thereby exacerbating the problem. Thus, the WHO recommends syndromic management of STIs for delivering care where lab testing is scarce or unattainable (1). This approach utilizes the use of an easy to use algorithm to help healthcare workers recognize symptoms/signs so as to provide treatment for the likely cause of the syndrome. Furthermore, according to the WHO, syndromic management offers instant and legitimate treatment compared to clinical diagnosis, and that it is also more cost-effective for some syndromes over the use of laboratory testing (1). In addition, even though it has been shown that the vaginal discharge syndrome has low specificity for gonorrhea and Chlamydia and can lead to over treatment (1), this is the recommended way to manage STIs in developing nations. Thus, the purpose of this paper is to specifically address the following questions: is syndromic management working to lower the STI burden in developing nations? How effective is it, and should it still be recommended? To answer these questions, a systematic literature review was conducted to evaluate the current effectiveness of syndromic management in developing nations. This review examined published articles over the past 5 years that compared syndromic management to laboratory testing and had published sensitivity, specificity, and positive predicative value data. Focusing mainly on vaginal discharge, urethral discharge, and genital ulcer algorithms, it was seen that though syndromic management is more effective in diagnosing and treating urethral and genial ulcer syndromes in men, there still remains an urgent need to revise the WHO recommendations for managing STIs in developing nations. Current studies have continued to show decreased specificity, sensitivity and positive predicative values for the vaginal discharge syndrome, and high rates of asymptomatic infections and healthcare workers neglecting to follow guidelines limit the usefulness of syndromic management. Furthermore, though advocate d as cost-effective by the WHO, there is a cost incurred from treating uninfected people. Instead of improving this system, it is recommended that better and less expensive point of care and the development of rapid test diagnosis kits be the focus and method of diagnosis and treatment in developing nations for STI management. ^
Resumo:
Background. The population-based Houston Tuberculosis Initiative (HTI) study has enrolled and gathered demographic, social, behavioral, and disease related data on more than 80% of all reported Mycobacterium Tuberculosis (MTB) cases and 90% of all culture positive patients in Houston/Harris County over a 9 year period (from October 1995-September 2004). During this time period 33% (n=1210) of HTI MTB cases have reported a history of drug use. Of those MTB cases reporting a history of drug use, a majority of them (73.6%), are non-injection drug users (NIDUs). ^ Other than HIV, drug use is the single most important risk factor for progression from latent to infectious tuberculosis (TB). In addition, drug use is associated with increased transmission of active TB, as seen by the increased number of clonally related strains or clusters (see definition on page 30) found in this population. The deregulatory effects of drug use on immune function are well documented. Associations between drug use and increased morbidity have been reported since the late 1970's. However, limited research focused on the immunological consequence of non-injection drug use and its relation to tuberculosis infection among TB patients is available. ^ Methods. TB transmission patterns, symptoms, and prevalence of co-morbidities were a focus of this project. Smoking is known to suppress Nitric Oxide (NO) production and interfere with immune function. In order to limit any possible confounding due to smoking two separate analyses were done. Non-injection drug user smokers (NIDU-S) were compared to non-drug user smokers (NDU-S) and non-injection drug user non-smokers (NIDU-NS) were compared to non-drug user non-smokers (NDU-NS) individually. Specifically proportions, chi-square p-values, and (where appropriate) odds ratios with 95% confidence intervals were calculated to assess characteristics and potential associations of co-morbidities and symptoms of TB among NIDUs HTI TB cases. ^ Results. Significant differences in demographic characteristics and risk factors were found. In addition drug users were found to have a decreased risk for cancer, diabetes mellitus, and chronic pulmonary disease. They were at increased risk of having HIV/AIDS diagnosis, liver disease, and trauma related morbidities. Drug users were more likely to have pulmonary TB disease, and a significantly increased amount of clonally related strains of TB or "clusters" were seen in both smokers and non-smoker drug users when compared to their non-drug user counterparts. Drug users are more likely to belong to print groups (clonally related TB strains with matching spoligotypes) including print one and print three and the Beijing family group, s1. Drug users were found to be no more likely to experience drug resistance to TB therapy and were likely to be cured of disease upon completion of therapy. ^ Conclusion. Drug users demographic and behavioral risk factors put them at an increased risk contracting and spreading TB disease throughout the community. Their increased levels of clustering are evidence of recent transmission and the significance of certain print groups among this population indicate the transmission is from within the social family. For these reasons a focus on this "at risk population" is critical to the success of future public health interventions. Successful completion of directly observed therapy (DOT), the tracking of TB outbreaks and incidence through molecular characterization, and increased diagnostic strategies have led to the stabilization of TB incidence in Houston, Harris County over the past 9 years and proven that the Houston Tuberculosis Initiative has played a critical role in the control and prevention of TB transmission. ^
Resumo:
Activation of Rho family small G proteins is thought to be a critical event in breast cancer development and metastatic progression. Rho protein activation is stimulated by a family of enzymes known as guanine nucleotide exchange factors (Rho GEFs). The neuroepithelioma transforming gene 1 (Net1) is a Rho GEF specific for the RhoA subfamily that is overexpressed in primary breast tumors and breast cancer cell lines. Net1 isoform expression is also required for migration and invasion of breast cancer cells in vitro. These data indicate that Net1 may be a critical regulator of metastatic progression in breast cancer. Net1 activity is negatively regulated by sequestration in the nucleus, and relocalization of Net1 outside the nucleus is required to stimulate RhoA activation, actin cytoskeletal reorganization, and oncogenic transformation. However, regulatory mechanisms controlling the extranuclear localization of Net1 have not been identified. In this study, we have addressed the regulation of Net1A isoform localization by Rac1. Specifically, co-expression of constitutively active Rac1 with Net1A stimulates the relocalization of Net1A from the nucleus to the plasma membrane in breast cancer cells, and results in Net1A activation. Importantly, Net1A localization is also driven by endogenous Rac1 activity. Net1A relocalizes outside the nucleus in cells spreading on collagen, and when endogenous Rac1 expression was silenced by siRNA, Net1A remained nuclear in spreading cells. These data indicate that Rac1 controls the localization of the Net1A isoform and suggests a physiological role for Net1A in breast cancer cell adhesion and motility.
Resumo:
Familial hemiplegic migraine type 1 (FHM1) is an autosomal dominant subtype of migraine with aura that is associated with hemiparesis. As with other types of migraine, it affects women more frequently than men. FHM1 is caused by mutations in the CACNA1A gene, which encodes the alpha1A subunit of Cav2.1 channels; the R192Q mutation in CACNA1A causes a mild form of FHM1, whereas the S218L mutation causes a severe, often lethal phenotype. Spreading depression (SD), a slowly propagating neuronal and glial cell depolarization that leads to depression of neuronal activity, is the most likely cause of migraine aura. Here, we have shown that transgenic mice expressing R192Q or S218L FHM1 mutations have increased SD frequency and propagation speed; enhanced corticostriatal propagation; and, similar to the human FHM1 phenotype, more severe and prolonged post-SD neurological deficits. The susceptibility to SD and neurological deficits is affected by allele dosage and is higher in S218L than R192Q mutants. Further, female S218L and R192Q mutant mice were more susceptible to SD and neurological deficits than males. This sex difference was abrogated by ovariectomy and senescence and was partially restored by estrogen replacement, implicating ovarian hormones in the observed sex differences in humans with FHM1. These findings demonstrate that genetic and hormonal factors modulate susceptibility to SD and neurological deficits in FHM1 mutant mice, providing a potential mechanism for the phenotypic diversity of human migraine and aura.
Resumo:
Band 4.1B is a cytoskeletal adaptor protein that regulates various cellular behavior; however, the mechanisms by which Band 4.1B contributes to intracellular signaling are unclear. This project addresses in vivo and in vitro functions for Band 4.1B in integrin-mediated cell adhesion and signaling. Band 4.1B has been shown to bind to β8 integrin, although cooperative functions of these two proteins have not been determined. Here, functional links between β8 integrin and Band 4.1B were investigated using gene knockout strategies. Ablation of β8 integrin and Band 4.1B genes resulted in impaired cardiac morphogenesis, leading to embryonic lethality by E11.5. These embryos displayed malformation of the outflow tract that was likely linked to abnormal regulation of cardiac neural crest migration. These data indicate the importance of cooperative signaling between β8 integrin and Band 4.1B in cardiac development. The involvement of Band 4.1B in integrin-mediated cell adhesion and signaling was further demonstrated by studying its functional roles in vitro. Band 4.1B is highly expressed in the brain, but its signaling in astrocytes is not understood. Here, Band 4.1B was shown to promote cell spreading likely by interacting with β1 integrin via its band 4.1, ezrin, radixin, and moesin (FERM) domain in cell adhesions. In astrocytes, both Band 4.1B and β1 integrin were expressed in cell-ECM contact sites during early cell spreading. Exogenous expression of Band 4.1B, especially its FERM domain, enhanced cell spreading on fibronectin, an ECM ligand for β1 integrin. However, the increased cell spreading was prohibited by blocking β1 integrin. These findings suggest that Band 4.1B is crucial for early adhesion assembly and/or signaling that are mediated by β1 integrin. Collectively, this study was the first to establish Band 4.1B as a modulator of integrin-mediated adhesion and signaling.
Resumo:
In order to more fully understand the function of surface GalTase on mesenchymal cells, anti-GalTase IgG was used to (a) examine the role of surface GalTase during mouse mesenchymal cell migration on laminin and fibronectin; (b) define the plasma membrane distribution of GalTase by indirect immunofluorescence on migrating cells; (c) quantitate the level of surface GalTase on migrating cells; and (d) determine whether GalTase is associated with the cytoskeleton.^ Results show that anti-GalTase IgG was able to inhibit migration (48-80% as compared to basal rate) when cells were migrating on laminin-containing matrices. Monovalent Fab fragments inhibited migration on laminin by 90% after 4 hours. On the other hand, anti-GalTase IgG had no effect on cells migrating on fibronectin. This illustrates the substrate specificity of GalTase mediated-migration. When anti-GalTase IgG was used to localize surface GalTase on cells migratory on laminin, the enzyme was restricted to the leading and trailing edges of the cell. Assays indicate that GalTase is elevated approximately 3-fold when cells are migrating on laminin-containing matrices as compared to migratory cells on plastic or fibronectin, or as compared to stationary cells on any substrate. Laminin appears to recruit GalTase from preexisting intracellular pools to the growing lamellipodia.^ Double-label indirect immunofluorescence studies indicate that there is an apparent co-localization between some of the surface GalTase and some actin filaments. This relationship was explored by extracting cells prelabeled with anti-GalTase IgG and quantitated by radiolabeled second antibodies. Results show that 79% of the surface GalTase is associated with the cytoskeleton (as judged by detergent insolubility) when monovalent antibodies (Fab) are used. However virtually all (80-100%) of the surface GalTase can be induced to associate with the cytoskeleton when cross-linked with bivalent antibodies. Furthermore, when cells in suspension are incubated with divalent antibodies, an additional 66% of the surface GalTase can be induced to associate with the cytoskeleton. The elevated levels of surface GalTase detectable on cells migrating on laminin also appear to be associated with the cytoskeleton.^ Several lines of evidence suggest that GalTase is associated with F-actin. Data suggest that laminin induces the expression of surface GalTase to the growing lamellipodia where it becomes associated with the cytoskeleton leading to cell spreading and migration. (Abstract shortened with permission of author.) ^
Resumo:
The integrin receptor $\alpha 4\beta 1$ is a cell surface heterodimer involved in a variety of highly regulated cellular interactions. The purpose of this dissertation was to identify and characterize unique structural and functional properties of the $\alpha 4\beta 1$ molecule that may be important for adhesion regulation and signal transduction. To study these properties and to establish a consensus sequence for the $\alpha 4$ subunit, cDNA encoding $\alpha 4$ was cloned and sequenced. A comparison with previously described human $\alpha 4$ sequences identified several substitutions in the $5\prime$ and $3\prime$ untranslated regions, and a nonsynonymous G to A transition in the coding region, resulting in a glutamine substitution for arginine. Further analysis of this single nucleotide substitution indicated that two variants of the $\alpha 4$ subunit exist, and when compared with three ancestrally-related species, the new form cloned in our laboratory was found to be evolutionarily conserved.^ The expression of $\alpha 4$ cDNA in transfected K562 erythroleukemia cells, and subsequent studies using flow cytofluorometric, immunochemical, and ligand binding/blocking analyses, confirmed $\alpha 4\beta 1$ as a receptor for fibronectin (FN) and vascular cell adhesion molecule-1 (VCAM-1), and provided a practical means of identifying two novel monoclonal antibody (mAb) binding epitopes on the $\alpha 4\beta 1$ complex that may play important roles in the regulation of leukocyte adhesion.^ To investigate the association of $\alpha 4\beta 1$-mediated adhesion with signals involved in the spreading of lymphocytes on FN, a quantitative method of analysis was developed using video microscopy and digital imaging. The results showed that HPB-ALL $(\alpha 4\beta 1\sp{\rm hi},\ \alpha 5\beta 1\sp-)$ cells could adhere and actively spread on human plasma FN, but not on control substrate. Many cell types which express different levels of the $\alpha 4\beta 1$ and $\alpha 5\beta 1$ FN binding integrins were examined for their ability to function in these events. Using anti-$\alpha 4$ and anti-$\alpha 5$ mAbs, it was determined that cell adhesion to FN was influenced by both $\beta 1$ integrins, while cell spreading was found to be dependent on the $\alpha 4\beta 1$ complex. In addition, inhibitors of phospholipase A$\sb2$ (PLA$\sb2$), 5-lipoxygenases, and cyclooxygenases blocked HPB-ALL cell spreading, yet had no effect on cell adhesion to FN, and the impaired spreading induced by the PLA$\sb2$ inhibitor cibacron blue was restored by the addition of exogenous arachidonic acid (AA). These results suggest that the interaction of $\alpha 4\beta 1$ with FN, the activation of PLA$\sb2,$ and the subsequent release of AA, may be involved in lymphocyte spreading. ^
Resumo:
Adhesion involves interactions between cells or cells with extracellular matrix components and is a fundamental process for all multicellular organisms as well as many pathogenic microbes. Integrins are heterodimeric transmembrane proteins that function as adhesion molecules and transduce signals between the extracellular environment and the intracellular cytoskeletal machinery. β1 integrin subfamily is highly expressed on T lymphocytes and mediates cell spreading, adhesion and coactivation. T lymphocytes have an important role in the regulation and homeostasis of the immune system therefore, the goals of this study were to first to investigate β1 integrin interaction with fibronectin binding protein A (FnbpA), a surface protein expressed on gram-negative bacteria Staphylococcus aureus. Second, characterize the association and function of a non-integrin surface protein, CD98, with β1 integrins on T lymphocytes. ^ FnbpA binds to fibronectin (FN), also a ligand for α5β1 and α4β1 integrins on T lymphocytes. Since both bacterial proteins FnbpA and T cell integrins utilize FN, it was of interest to determine the effects FnbpA on T cell activation. Results demonstrated that recombinant FnbpA (rFnbpA) coimmobilized with OKT3 mediated T cell coactivation in a soluble FN-dependent manner. Integrin α5β1 was identified as the main integrin utilized by Staphylococcus aureus FnbpA from studies using soluble antibodies to inhibit T cell proliferation and parallel plate flow chamber assays. The mechanism of rFnbpA-mediated coactivation was one that used soluble FN as a bridge between rFnbpA and integrin α5β1 on the T lymphocyte. ^ Since integrins are utilized by T lymphocytes and bacterial proteins, it was of interest to identify proteins involved in integrin regulation. Anti-CD98 mAb 80A10 was identified and characterized from a screen to identify surface proteins involved in integrin signaling and functions. CD98 is a non-integrin protein that was sensitive to integrin inhibition in human T lymphocyte aggregation and activation, thus suggested that CD98 shared a common signaling pathway with integrins. These results led to the question of whether CD98 physically associates with β1 integrins. Fluorescence microscopy and biochemical analysis determined that CD98 is specifically associated with β1 integrin on human T lymphocytes and may be part of a larger multimolecular signaling complex. ^
Resumo:
Trehalose dimycolate (TDM) is a mycobacterial glycolipid that is released from the surface of virulent M. tuberculosis. We evaluated the rate of growth, colony characteristics and production of TDM by Mycobacterium tuberculosis strains isolated from different clinical sites. Since detergent removes TDM from organisms, we analyzed growth rate and colony morphology of 79 primary clinical isolates grown as pellicles on the surface of detergent free Middlebrook 7H9 media. The genotype of each had been previously characterized. TDM production was measured by thin layer chromatography on 32 of these isolates. We found that strains isolated from pulmonary sites produced large amounts of TDM, grew rapidly as thin spreading pellicles, showed early cording (<1 week) and climbed the sides of the dish. In contrast, the extrapulmonary isolates (lymph node and bone marrow) produced less TDM (p<0.01), grew as discrete patches with little tendency to spread or climb the walls (p<0.02). The Beijing pulmonary (BP) isolates produced more TDM than non Beijing pulmonary isolates. The largest differences were observed in Beijing strains. The Beijing pulmonary isolates produced more TDM and grew faster than the Beijing extrapulmonary isolates (p<0.01). This was true even when the pulmonary and extrapulmonary isolates were derived from the same clade. These growth characteristics were consistently observed only on the first passage after primary isolation. This suggests that the differences in growth rate and TDM production observed reflect differences in gene expression patterns of pulmonary and extrapulmonary infections, that Mycobacterium tuberculosis in the lung grows more rapidly and produces more TDM than it does in extrapulmonary sites. This provides new opportunities to investigate gene expression of Mycobacterium tuberculosis in human.^