Publications

Respiratory failure is a major cause of mortality during septic shock and is due in part to decreased ventilatory muscle contraction. Ventilatory muscles have high energy demands; fatty acid (FA) oxidation is an important source of ATP. FA oxidation is regulated by nuclear hormone receptors; studies have shown that the expression of these receptors is decreased in liver, heart, and kidney during sepsis. Here, we demonstrate that lipopolysaccharide (LPS) decreases FA oxidation and the expression of lipoprotein lipase (LPL), FA transport protein 1 (FATP-1), CD36, carnitine palmitoyltransferase beta, medium chain acyl-CoA dehydrogenase (MCAD), and acyl-CoA synthetase, key proteins required for FA uptake and oxidation, in the diaphragm. LPS also decreased mRNA levels of PPARalpha and beta/delta, RXRalpha, beta, and gamma, thyroid hormone receptor alpha and beta, and estrogen related receptor alpha (ERRalpha) and their coactivators PGC-1alpha, PGC-1beta, SRC1, SRC2, Lipin 1, and CBP. Zymosan resulted in similar changes in the diaphragm. Finally, in PPARalpha deficient mice, baseline CPT-1beta and FATP-1 levels were markedly decreased and were not further reduced by LPS suggesting that a decrease in the PPARalpha signaling pathway plays an important role in inducing some of these changes. The decrease in FA oxidation in the diaphragm may be detrimental, leading to decreased diaphragm contraction and an increased risk of respiratory failure during sepsis.

BACKGROUND & AIMS

The management of inflammatory bowel disease (IBD) has become increasingly complicated, and it is unknown whether poor outcomes (prolonged steroid use, hospitalizations, and surgery) have declined in the general population.

METHODS

This multilevel study used computerized clinical data. The study comprised 2892 adults with Crohn's disease (CD) and 5895 with ulcerative colitis (UC) who received care at 16 medical centers within an integrated care organization in Northern California between 1998 and 2005.

RESULTS

Time trends included (1) a shift in gastroenterology-related visits from the gastroenterology division to primary care; (2) increased use of IBD-related drugs, except for a 7% decline in use of 5-aminosalicylate in CD and no change in steroid use for CD; (3) for the prevalence of prolonged steroid exposure (120 days of continuous use), a 36% decline for CD with a 27% increase for UC; (4) declines in the hospitalization rates of 33% for CD and 29% for UC; and (5) for the surgery rate, no significant change for CD with a 50% decline for UC.

CONCLUSIONS

Declines in prolonged steroid exposure and the hospitalization rate for CD and in the hospitalization and surgery rate for UC are encouraging; however, the increase in prolonged steroid exposure for UC merits concern and further investigation. The variability in care patterns observed in this study suggests lack of standardization of care and the opportunity to identify targets for quality improvement. These findings should stimulate research to quantify the effect of current trends in IBD management.

Prior evidence suggests that the health and longevity benefits of antiretroviral therapy (ART) for persons living with AIDS (PLWAs) have not been equally distributed across racial/ethnic groups in the United States. Notably, black PLWAs tend to fare worse than their counterparts. We examine the role of neighborhood socioeconomic context on racial/ethnic differences in AIDS treatment and survival in San Francisco. The study population encompassed 4211 San Francisco residents diagnosed with AIDS between 1996 and 2001. Vital status was reported through 2006. Census data were used to define neighborhood-level indicators of income, housing, demographics, employment and education. Cox proportional hazards models were employed in multivariate analyses of survival times. Compared to whites, blacks had a significant 1.4 greater mortality hazard ratio (HR), which decreased after accounting for ART initiation. PLWAs in the lowest socioeconomic neighborhoods had a significant HR of 1.4 relative to those in higher socioeconomic neighborhoods, independent of race/ethnicity. The neighborhood association decreased after accounting for ART initiation. Path analysis was used to explore causal pathways to ART initiation. Racial/ethnic differences in neighborhood residence accounted for 19-22% of the 1.6-1.8 black-white relative odds ratio (ROR) and 14-15% of the 1.3-1.4 Latino-white ROR for delayed or no treatment. Our findings illuminate the independent and synergistic contributions of race and place on treatment disparities and highlight the need for future studies and interventions to address treatment initiation as well as neighborhood effects on treatment differences.

The transient receptor potential vanilloid 4 (TRPV4) contributes to mechanical hyperalgesia of diverse etiologies, presumably as part of a mechanoreceptor signaling complex (Alessandri-Haber et al., 2008). To investigate the hypothesis that a functional interaction between TRPV4 and stretch-activated ion channels (SACs) is involved in this mechanical transduction mechanism, we used a selective SACs inhibitor, GsMTx-4. Intradermal injection of GsMTx-4 in the rat hindpaw reversed the mechanical hyperalgesia induced by intradermal injection of inflammatory mediators. In vivo single fiber recordings showed that GsMTx-4 reversed inflammatory mediator-induced decrease in mechanical threshold in half of sensitized C-fibers. Furthermore, GsMTx-4 reduced hyperalgesia to both mechanical and hypotonic stimuli in different models of inflammatory and neuropathic pain, although it had no effect on baseline mechanical nociceptive thresholds. TRPC1 and TRPC6, two GsMTx-4-sensitive SACs, are expressed in dorsal root ganglion (DRG) neurons. Single-cell reverse transcription-PCR showed that messenger RNAs for TRPV4, TRPC1, and TRPC6 are frequently coexpressed in DRG neurons. Spinal intrathecal administration of oligodeoxynucleotides antisense to TRPC1 and TRPC6, like that to TRPV4, reversed the hyperalgesia to mechanical and hypotonic stimuli induced by inflammatory mediators without affecting baseline mechanical nociceptive threshold. However, antisense to TRPC6, but not to TRPC1, reversed the mechanical hyperalgesia induced by a thermal injury or the TRPV4-selective agonist 4alpha-PDD (4 alpha-phorbol 12,13-didecanoate). We conclude that TRPC1 and TRPC6 channels cooperate with TRPV4 channels to mediate mechanical hyperalgesia and primary afferent nociceptor sensitization, although they may have distinctive roles.