Publications

Keratinocyte growth factor (KGF) has efficacy in several experimental models of lung injury; however, the mechanisms underlying KGF's protective effect remain incompletely understood. This study was undertaken to determine whether KGF augments barrier function in primary rat alveolar epithelial cells grown in culture, specifically whether KGF alters tight junction function via claudin expression. KGF significantly increased alveolar epithelial barrier function in culture as assessed by transepithelial electrical resistance (TER) and paracellular permeability. Fluorescence-activated cell sorting of freshly isolated type 1 (AT1) and type 2 (AT2) cells followed by quantitative real-time RT-PCR revealed that more than 97% of claudin mRNA transcripts in these cells were for claudins-3, -4, and -18. Using cultured AT2 cells, we then examined the effect of KGF on the protein levels of the claudins with the highest mRNA levels: -3, -4, -5, -7, -12, -15, and -18. KGF did not alter the levels of any of the claudins tested, nor of zona occludens-1 (ZO-1) or occludin. Moreover, localization of claudins-3, -4, -18, and ZO-1 was unchanged. KGF did induce a marked increase in the apical perijunctional F-actin ring. Actin depolymerization with cytochalasin D blocked the KGF-mediated increase in TER without significantly changing TER in control cells. Together, these data support a novel mechanism by which KGF enhances alveolar barrier function, modulation of the actin cytoskeleton. In addition, these data demonstrate the complete claudin expression profile for AT1 and AT2 cells and indicate that claudins-3, -4, and -18 are the primary claudins expressed in these cell types.

BACKGROUND

Previous research has demonstrated an increase in carotid intima-media thickness (cIMT) in HIV-infected individuals compared to controls. However, the reason for this increased level of subclinical vascular disease is unknown.

OBJECTIVE

To identify HIV-related risk factors for increased cIMT.

METHODS

We evaluated the relationship between HIV-related characteristics (including markers of HIV disease severity and use of antiretroviral therapy) and cIMT measurements in the internal/bulb and common carotid regions among 538 HIV-infected participants from the Study of Fat Redistribution and Metabolic Change in HIV Infection (FRAM). We used Bayesian model averaging to estimate the posterior probability of candidate HIV and non-HIV-related risk factors being true predictors of increased cIMT. Variables with a posterior probability of more than 50% were used to develop a selected regression model for each of the anatomic regions.

RESULTS

For common cIMT, the Bayesian model selection process identified age, African-American race, and systolic and diastolic blood pressure with probability more than 95%, HDL cholesterol with probability 85% and Hispanic ethnicity with probability 51%. Among the HIV-related factors included in the analysis, only tenofovir use was selected (51% probability). In the selected model, duration of tenofovir use was associated with lower common cIMT (-0.0094 mm/year of use; 95% confidence interval: -0.0177 to -0.0010). For internal cIMT, no HIV-related risk factors were above the 50% posterior probability threshold.

CONCLUSION

We observed an inverse association between duration of tenofovir use and common carotid cIMT. Whether this association is causal or due to confounding by indication needs further investigation.

Bacterial binding to human platelets is an important step in the pathogenesis of infective endocarditis. Streptococcus gordonii can mediate its platelet attachment through a cell wall glycoprotein termed GspB ('gordonii surface protein B'). GspB export is mediated by a seven-component accessory Sec system, containing two homologues of the general secretory pathway (SecA2 and SecY2) and five accessory Sec proteins (Asps1-5). Here we show that the Asps are required for optimal export of GspB independent of the glycosylation process. Furthermore, yeast two-hybrid screening of the accessory Sec system revealed interactions occurring between Asp3 and the other components of the system. Asp3 was shown to bind SecA2, Asp1, Asp2 and itself. Mutagenesis of Asp3 identified N- and C-terminal regions that are essential for GspB transport, and conserved residues within the C-terminal domain mediated Asp3 binding to other accessory Sec components. The loss of binding by Asp3 also resulted in an impaired ability of S. gordonii to secrete GspB. These studies indicate that Asp3 is a central element mediating multiple interactions among accessory Sec components that are essential for GspB transport to the cell surface.

PURPOSE

Initial weight loss improves urinary incontinence in overweight and obese women. In this study we examined the longer term effects of a weight loss intervention on urinary incontinence.

MATERIALS AND METHODS

Overweight and obese women (mean +/- SD age 53 +/- 10 years) with 10 or more urinary incontinence episodes weekly were randomized to an 18-month behavioral weight loss intervention (226) or control group (112). Outcome measures were collected at 12 and 18 months.

RESULTS

At baseline women had a mean body mass index of 36 +/- 6 kg/m(2) and reported a mean of 24 +/- 18 incontinence episodes weekly. Of the patients 86% completed 18-month measurements. The percent weight loss in the intervention group averaged 8.0%, 7.5% and 5.5% at 6, 12 and 18 months, respectively, vs approximately 1.5% in the control group (all values p <0.001). Compared with controls at 12 months the intervention group reported a greater percent reduction in weekly stress urinary incontinence episodes (65% vs 47%, p <0.001), and a greater proportion achieved at least a 70% decrease in weekly total and stress urinary incontinence episodes. At 18 months a greater proportion of women in the weight loss intervention group had more than 70% improvement in urge incontinence episodes but there were no significant differences between the groups for stress or total urinary incontinence. The intervention group also reported greater satisfaction with changes in urinary incontinence than the control group at 6, 12 and 18 months.

CONCLUSIONS

Weight loss intervention reduced the frequency of stress incontinence episodes through 12 months and improved patient satisfaction with changes in incontinence through 18 months. Improving weight loss maintenance may provide longer term benefits for urinary incontinence.