Publications

Coxsackievirus A9 (CAV9), a member of the Enterovirus genus of Picornaviridae, is a common human pathogen and is one of a significant number of viruses containing a functional arginine-glycine-aspartic acid (RGD) motif in one of their capsid proteins. Previous studies identified the RGD-recognizing integrin alpha(v)beta(3) as its cellular receptor. However, integrin alpha(v)beta(6) has been shown to be an efficient receptor for another RGD-containing picornavirus, foot-and-mouth disease virus (FMDV). In view of the similarity in sequence context of the RGD motifs in CAV9 and FMDV, we investigated whether alpha(v)beta(6) can also serve as a receptor for CAV9. We found that CAV9 can bind to purified alpha(v)beta(6) and also to SW480 cells transfected with beta(6) cDNA, allowing expression of alpha(v)beta(6) on their surface, but it cannot bind to mock-transfected cells. In addition, a higher yield of CAV9 was obtained in beta(6)-expressing cells than in mock-transfected cells. There was no similar enhancement in infection with an RGD-less CAV9 mutant. We also found beta(6) on the surface of GMK cells, a cell line which CAV9 infects efficiently by an RGD-dependent mechanism. Significantly, this infection is blocked by an antibody to alpha(v)beta(6), while this antibody did not block the low level of infection by the RGD-less mutant. Thus, integrin alpha(v)beta(6) is an RGD-dependent receptor for CAV9 and may be important in natural CAV9 infections.

OBJECTIVE

To determine whether clinically relevant airspace concentrations of beta2-adrenergic agonists stimulated maximal alveolar fluid clearance rates and to determine whether beta2 agonist therapy decreased pulmonary edema in experimental acute lung injury.

DESIGN

Prospective randomized laboratory investigation.

SETTING

University-affiliated laboratory.

SUBJECTS

Sprague Dawley rats.

INTERVENTIONS

Dibutyryl cyclic adenosine monophosphate (cAMP), salmeterol, albuterol, and isoproterenol in normal rat lung. Salmeterol in a rat model of acid-induced lung injury.

MEASUREMENTS AND MAIN RESULTS

Basal alveolar fluid clearance was 7.6 +/- 2.2 %/hr. Maximal cAMP-dependent alveolar fluid clearance rate was 32.9 +/- 10.9 %/hr (p <.05). Racemic albuterol 10(-5) M, salmeterol 10(-6) M, and isoproterenol 10(-6) M each stimulated alveolar fluid clearance to a level comparable to maximal cAMP-dependent alveolar fluid clearance. Compared with basal rates, alveolar fluid clearance was increased by both racemic albuterol 10(-6) M (14.5 +/- 3.0%, p <.05) and R-enantiomer 10(-6) M (15.0 +/- 4.6%, p <.05), but there was no difference between the two groups. Intra-alveolar salmeterol 10 (-6) M attenuated the degree of pulmonary edema following acid-induced lung injury. Extravascular lung water increased to only 180 +/- 30 microL with salmeterol treatment, compared with 296 +/- 65 microL in saline-treated rats 4 hrs after acid injury (p <.05). This decrease in lung water was accompanied by a 2.4-fold increase in the rate of alveolar fluid clearance at 4 hrs in the salmeterol-treated group. Lung endothelial permeability, expressed as extravascular plasma equivalents, was reduced to 64 +/- 9 microL with salmeterol compared with 119 +/- 51 microL in saline-treated rats 4 hrs after acid injury (p <.05).

CONCLUSIONS

Clinically relevant airspace concentrations of beta2-adrenergic agonists a) stimulate maximal cAMP-dependent airspace fluid clearance in normal lungs and b) reduce pulmonary edema in acid aspiration-induced lung injury by increasing alveolar fluid clearance and decreasing endothelial permeability. Clinical studies are required to determine whether beta2-adrenergic agonists improve outcome in patients with acute lung injury.

PURPOSE

To determine whether female sex-steroid hormones and their metabolites can modulate P-glycoprotein (P-gp) expression and catalytic activity and to investigate P-gp mediated transport of these sex-steroids across MDR1-transfected Madine-Darby canine kidney (MDCK) cells.

METHODS

Changes in P-gp protein and MDR1 mRNA expression levels were examined in the presence of various estrogens and progestins after a 72-h induction period in the LS180 human colon carcinoma cell line via Western blotting and semiquantitative Reverse-transcription-polymerase chain reaction (RT-PCR), respectively. Concentration-dependent stimulation of vanadate-sensitive P-gp ATPase activity was measured in membranes of Sf9 insect cells infected with a recombinant baculovirus containing the human MDR1 cDNA used with appropriate control membranes. MDCK and MDR1-transfected MDCK cell lines were then used to measure bidirectional P-gp transport of various steroids in the presence and absence of the P-gp inhibitor, GG918. Samples obtained were quantified using LC/MS.

RESULTS

Our findings show that P-gp protein levels are inducible by estrone (4-fold over control), estriol (2-fold), and ethynyl estradiol (3-fold). MDR1 mRNA expression levels were also inducible in a concentration-dependent manner from 25 nM to 10 microM. Bidirectional transport studies indicate that ethynyl estradiol, estrone, and estriol are all substrates for P-gp with respective efflux ratios of 10.3, 6.9, and 2.8. Norethindrone was not found to be a substrate for P-gp. Ethynyl estradiol and progesterone were able to significantly stimulate P-gp ATPase activity in a concentration-dependent manner.

CONCLUSIONS

Our studies indicate that several sex-steroid hormones are substrates for P-gp-mediated transport and are also able to induce P-gp expression at both the protein and mRNA level in vitro. Stimulation of P-gp ATPase catalytic activity by steroid hormones was also observed, suggesting physical interactions and identifying a need for further investigations to understand the in vivo effects of endogenous and synthetic steroid hormones on the expression and function of P-gp.

BACKGROUND

Although the majority of studies examining racial/ethnic disparities in health care have focused on the characteristics of the individual, more recently there has been growing attention to the notion that an individual's health practices could be influenced by the characteristics of the place where they reside.

OBJECTIVE

The objective of this study was to examine whether access to care for individuals of different racial/ethnic groups varies by the prevalence of blacks and the prevalence of Latinos in their county of residence.

STUDY DESIGN

We conducted a cross-sectional cohort.

PARTICIPANTS

Individuals from the 1996 Medical Expenditure Panel Survey, a nationally representative sample of U.S. households, who described their race/ethnicity as white, black, or Latino, and who resided in 1 of 677 counties (n = 14740) were studied.

MEASURES

Counties were assigned to 6 groups based on the prevalence of blacks and Latinos who resided there (<6% referred to as "low prevalence," 6-39% referred to as "midprevalence," >or=40% referred to as "high prevalence" separately for both blacks and Latinos). Outcomes included whether during the past year any family members: 1). experienced difficulty obtaining any type of health care, delayed obtaining care, or did not receive health care they thought they needed (referred to as "difficulty obtaining care"); or (2). did not receive a doctor's care or a prescription medication because the family needed money to buy food, clothing, or pay for housing (referred to as "financial barriers").

RESULTS

After controlling for other individual and area-level covariates, blacks reported lower rates of both outcome variables when they lived in a county with a high prevalence of blacks compared with blacks who lived in a county with a low prevalence of blacks (difficulty obtaining care: 4.3% vs. 18.8%, P <0.005; financial barriers: 1.6% vs. 10.5%, P <0.005). There was a similar association for Latinos by the prevalence of Latinos in the county for difficulty obtaining care (high: 5.0% vs. low: 13.4%, P <0.05), but not the financial barriers outcome (high: 2.2% vs. low: 2.4%, P = 0.90). Whites who lived in an area with a high prevalence of Latinos were more likely to report both outcomes compared with whites who lived in a county with a low prevalence of Latinos (difficulty obtaining care: 17.7% vs. 9.4%, P <0.05; financial barriers: 8.5% vs. 3.2%, P <0.005) .

CONCLUSIONS

Blacks and Latinos may perceive fewer barriers to care when they live in a county with a high prevalence of people of similar race/ethnicity. Conversely, whites may perceive more difficulty receiving care when they live in an area with a high prevalence of Latinos. Diminishing disparities in access to health care may require interventions that extend beyond the individual.

OBJECTIVES

To determine the potential impact of genetic testing and pharmacogenomics on healthcare delivery and costs.

STUDY DESIGN

Literature review.

METHODS

We examined 3 examples: (1) BRCA1/2 testing for breast cancer risk, (2) HER2/neu overexpression testing to guide drug treatment in women with breast cancer, and (3) CYP2C9 testing before the use of the anticoagulant warfarin. We discussed each genetic testing example from the perspective of the patient, provider, insurer, industry, government, and society.

RESULTS

The expanded use of genetic information offers many potential clinical benefits, but also many economic challenges. One of those challenges will be managing the impact of genetic testing on healthcare delivery and costs.

CONCLUSIONS

Systematic, evidence-based technology assessments and economic evaluations will have to be used to guide the incorporation of genomics into clinical practice. More research also will be needed to assess patient preferences and willingness to pay for genomic technologies; how providers can assess and use genomic technologies; and how the industry, insurers, and government can best balance the relevant costs and benefits.