PubMed Health⌕ Search

Biomedical subjects

Benjamin Davis

Publications and source records attributed to Benjamin Davis.

8 recordsLinked to original sources
PubMed2006

CRP promotes monocyte-endothelial cell adhesion via Fcgamma receptors in human aortic endothelial cells under static and shear flow conditions.

Monocyte-endothelial cell adhesion is a key early event in atherogenesis. C-reactive protein (CRP), a cardiovascular risk marker, is known to stimulate ICAM and VCAM in human aortic endothelial cells (HAEC) and induces monocyte-endothelial cell adhesion. In this study, we examined the mechanisms by which native CRP promotes monocyte-endothelial cell adhesion under static conditions and tested the effect of CRP on adhesion under shear flow. Incubation of HAEC with CRP (>25 microg/ml) upregulated NF-kappaB activity, and this resulted in a significant increase in ICAM (54% increase, P<0.001), VCAM (41% increase, P<0.01), and monocyte-endothelial cell adhesion (44% increase, P<0.02) compared with those of control. Preincubation with antibodies to CD32 and CD64 but not CD16 effectively inhibited this activation. Blocking NF-kappaB activity with inhibitors or a dominant negative inhibitory kappaB significantly decreased ICAM, VCAM upregulation, and subsequent monocyte-endothelial cell adhesion. Preincubation with antibodies to CD32 and CD64 or transient transfection with small interference RNA to CD32 attenuated CRP-induced NF-kappaB activity, ICAM, VCAM, and monocyte-endothelial cell adhesion under static conditions. Also, the Syk kinase inhibitor piceatannol and MG-132, a proteasome degradation inhibitor, produced similar attenuation in NF-kappaB activity, ICAM, VCAM, and adhesion. Furthermore, CRP-activated endothelial cells supported monocyte rolling, arrest, and transmigration in shear flow (2 dyn/cm2), and this was also inhibited by preincubation with antibodies to CD32 and CD64. Thus, in HAEC, CRP upregulates monocyte-endothelial adhesion by activation of NF-kappaB through engaging the Fcgamma receptors CD32 and CD64.

Antibodies↗
PubMed2005

Do conditional cash transfers influence migration? A study using experimental data from the Mexican PROGRESA program.

Prior research on Mexican migration has shown that social networks and economic incentives play an important role in determining migration outcomes. We use experimental data from PROGRESA, Mexico's primary poverty-reduction program, to evaluate the effects of conditional cash transfers on migration both domestically and to the United States. Our study complements a growing body of literature aimed at overcoming longstanding hurdles to the establishment of causal validity in empirical studies of migration. Analysis based on the data collected before and after the program's onset shows that conditional transfers reduce U.S. migration but not domestic migration. The data also enable us to explore the role of existing family and community migration networks. The results show that migration networks strongly influence migration, but that the effect of conditional transfers on migration is apparently not mediated by existing migration network structures. Our results suggest that conditional transfers may be helpful in managing rural out-migration, particularly to the United States.

Adolescent↗
PubMed2004

Effects of testosterone administration in human immunodeficiency virus-infected women with low weight: a randomized placebo-controlled study.

BACKGROUND: The prevalence of human immunodeficiency virus (HIV) disease is increasing among women, many of whom remain symptomatic with low weight and poor functional status. Although androgen levels may often be reduced in such patients, the safety, tolerability, and efficacy of testosterone administration in this population remains unknown. METHODS: A total of 57 HIV-infected women with free testosterone levels less than the median of the reference range and weight less than 90% of ideal body weight or weight loss greater than 10% were randomly assigned to receive transdermal testosterone (4 mg/patch) twice weekly or placebo for 6 months. Muscle mass was assessed by urinary creatinine excretion. Muscle function was assessed by the Tufts Quantitative Muscle Function Test. Treatment effect at 6 months was determined by analysis of covariance. Results are mean +/- SEM unless otherwise specified. RESULTS: At baseline, subjects were low weight (body mass index [calculated as weight in kilograms divided by the square of height in meters] 20.6 +/- 0.4), with significant weight loss from pre-illness maximum weight (18.7% +/- 1.2%), and demonstrated reduced muscle function (upper and lower extremity muscle strength, 83% and 67%, respectively, of predicted range). Testosterone treatment resulted in significant increases in testosterone levels vs placebo (total testosterone: 37 +/- 5 vs -2 +/- 2 ng/dL [1.3 +/- 0.2 vs -0.1 +/- 0.1 nmol/L] [P<.001]; free testosterone: 3.7 +/- 0.5 vs -0.4 +/- 0.3 pg/mL [12.8 +/- 1.7 vs -1.4 vs 1.0 pmol/L] [P<.001]) and was well tolerated, without adverse effects on immune function, lipid and glucose levels, liver function, or body composition or the adverse effect of hirsutism. Muscle mass tended to increase (1.4 +/- 0.6 vs 0.3 +/- 0.8 kg; P =.08), and shoulder flexion (0.4 +/- 0.3 vs -0.5 +/- 0.3 kg; P =.02), elbow flexion (0.3 +/- 0.4 vs -0.7 +/- 0.4 kg; P =.04), knee extension (0.2 +/- 1.0 vs -1.7 +/- 1.3 kg; P =.02), and knee flexion (0.7 +/- 0.5 vs 0.3 +/- 0.7 kg; P =.04) increased in the testosterone-treated compared with the placebo-treated subjects. CONCLUSIONS: Testosterone administration is well-tolerated and increases muscle strength in low-weight HIV-infected women. Testosterone administration may be a useful adjunctive therapy to maintain muscle function in symptomatic HIV-infected women.

Adult↗
PubMed2004

Adenovirus-mediated erythropoietin production by airway epithelia is enhanced by apical localization of the coxsackie-adenovirus receptor in vivo.

In well-differentiated human airway epithelia, the coxsackie B and adenovirus types 2 and 5 receptor (CAR) resides on the basolateral membrane. Replacing the transmembrane and cytoplasmic tail of CAR with a glycosyl-phosphatidylinositol anchor (GPI-CAR) allows apical localization of GPI-CAR, where it can bind adenovirus and enhance gene transfer in vitro. To test this hypothesis further and to investigate requirements and barriers we developed an in vivo model that quantitatively assesses gene transfer of erythropoietin (EPO) to mouse airway epithelia. Our data suggest that erythropoietin is secreted basolaterally, allowing possible access to the bloodstream. The data also suggest that basolateral adenovirus-mediated airway epithelia EPO secretion persists for long periods and could be used to study persistence in vivo. Additionally, the increase in hematocrit in response to the increased serum EPO could be used for therapeutic purposes. Finally, we tested the ability of apically localized CAR to enhance the infection of AdEPO in mouse airway epithelia in vivo. The data suggest that apical receptors in airway epithelia may be sufficient to improve adenovirus infection of airway epithelia in vivo.

Adenoviridae↗
PubMed2004

Femoral cement pressurization in hip arthroplasty: a laboratory comparison of three techniques.

BACKGROUND: Several cementing techniques are used for the proximal femur. MATERIAL AND METHODS: We evaluated 3 femoral cement pressurization techniques (standard, pressurizer in situ, and thumb pressurization) in 12 plastic femurs, with 4 sets of observations for each technique. Intramedullary pressure readings were obtained using proximal and distal pressure monitoring transducers. The peak pressure and the length of time for which the pressure was above a particular cutoff level (5 KPa and 100 KPa) were compared for the different techniques. RESULTS: We found significant differences between the 3 cementing techniques in the peak pressure and the length of time for which the pressure was above 100 KPa. The pressurizer in situ technique gave higher peak pressure (p < 0.001), both proximally (398) and distally (597). The standard technique produced a pressure of 100 KPa for a longer duration, both proximally and distally (mean 67 sec and 45 sec, p < 0.001) compared to the other two techniques (less than 5 and 17 sec for the thumb pressurization technique and the pressurizer in situ technique, respectively, both proximally and distally). Although the pressurizer in situ technique produced the highest peak pressure, the standard technique produced an optimum pressure of longer duration. INTERPRETATION: The standard technique appears to be adequate for achievement of optimum pressurization during femoral cementing without increased risk of embolization.

Arthroplasty, Replacement, Hip↗
PubMed2003

Augmentation of HIV-1-specific T helper cell responses in chronic HIV-1 infection by therapeutic immunization.

OBJECTIVE: To determine whether therapeutic immunization with a whole inactivated HIV-1 immunogen augments HIV-1-specific T helper cell responses in chronically infected individuals receiving suppressive antiretroviral therapy (ART). DESIGN: An investigator-initiated, single center, double-blind, placebo-controlled, randomized trial. METHODS: Subjects selected for study were HIV-1-infected adults on ART with an HIV-1-RNA plasma viral load of less than 500 copies/ml for at least 6 months, and a CD4 cell count greater than 250 cells/mm3 before starting ART. Study subjects were randomly assigned to receive either immunogen (inactivated envelope-depleted HIV-1 coupled with incomplete Freund's adjuvant; IFA), versus placebo (IFA alone). The primary outcome was significant CD4 cell lymphoproliferative responses to HIV-1 proteins. Secondary endpoints included HIV-1-specific CD8 T cell responses, CD4 cell count/percentage, HIV-1-RNA plasma viral load, and delayed-type hypersensitivity (DTH) responses. RESULTS: The augmentation of HIV-1-specific T helper cell responses was achieved in five out of five vaccine recipients and none out of four controls (P = 0.008, Fisher's exact test). There were no significant changes in the breadth or magnitude of cytotoxic T lymphocyte responses, CD4 cell count/percentages, or DTH test responses. CONCLUSION: HIV-1-specific T helper cell responses can be successfully increased by therapeutic immunization in individuals with chronic infection on suppressive ART. Further studies will be needed to determine whether the augmentation of these responses correlate with long-term clinical benefits.

AIDS Vaccines↗
PubMed2003

Prediction of coronary heart disease risk in HIV-infected patients with fat redistribution.

A metabolic syndrome has been described among human immunodeficiency virus (HIV)-infected patients receiving highly active antiretroviral therapy; the syndrome is characterized by fat redistribution, insulin resistance, and dyslipidemia. We compared the 10-year coronary heart disease (CHD) risk estimates for 91 HIV-infected men and women with fat redistribution with the risk estimates for 273 age-, sex-, and body mass index (BMI)-matched subjects enrolled in the Framingham Offspring Study. Thirty HIV-infected patients without fat redistribution were also compared with 90 age- and BMI-matched control subjects. The 10-year CHD risk estimate was significantly elevated among HIV-infected patients with fat redistribution, particularly among men; however, when they were matched with control subjects by waist-to-hip ratio, the 10-year CHD risk estimate did not significantly differ between groups. HIV-infected patients without fat redistribution did not have a greater CHD risk estimate than did control subjects. In addition, the CHD risk estimate was greatest in HIV-infected patients who had primary lipoatrophy, compared with those who had either lipohypertrophy or mixed fat redistribution. Therefore, although CHD risk is increased in HIV-infected patients with fat redistribution, the pattern of fat distribution and sex are potential important components in determining the risk in this population.

Adult↗