The present study examined the roles of peroxisome proliferator-activated receptors (PPAR) in activation of hepatic stellate cells (HSC), a pivotal event in liver fibrogenesis. RNase protection assay detected mRNA for PPAR␥1 but not that for the adipocyte-specific ␥2 isoform in HSC isolated from sham-operated rats, whereas the transcripts for neither isoforms were detectable in HSC from cholestatic liver fibrosis induced by bile duct ligation (BDL). Semi-quantitative reverse transcriptasepolymerase chain reaction confirmed a 70% reduction in PPAR␥ mRNA level in HSC from BDL. Nuclear extracts from BDL cells showed an expected diminution of binding to PPAR-responsive element, whereas NF-B and AP-1 binding were increased. Treatment of culturedactivated HSC with ligands for PPAR␥ (10 M 15-deoxy-⌬ 12,14 -PGJ 2 (15dPGJ 2 ); 0.1ϳ10 M BRL49653) inhibited DNA and collagen synthesis without affecting the cell viability. Suppression of HSC collagen by 15dPGJ 2 was abrogated 70% by the concomitant treatment with a PPAR␥ antagonist (GW9662). HSC DNA and collagen synthesis were inhibited by WY14643 at the concentrations known to activate both PPAR␣ and ␥ (>100 M) but not at those that only activate PPAR␣ (<10 M) or by a synthetic PPAR␣-selective agonist (GW9578). 15dPGJ 2 reduced ␣1(I) procollagen, smooth muscle ␣-actin, and monocyte chemotactic protein-1 mRNA levels while inducing matrix metalloproteinase-3 and CD36. 15dPGJ 2 and BRL49653 inhibited ␣1(I) procollagen promoter activity. Tumor necrosis factor ␣ (10 ng/ml) reduced PPAR␥ mRNA, and this effect was prevented by the treatment with 15dPGJ 2 . These results demonstrate that HSC activation is associated with the reductions in PPAR␥ expression and PPAR-responsive element binding in vivo and is reversed by the treatment with PPAR␥ ligands in vitro. These findings implicate diminished PPAR␥ signaling in molecular mechanisms underlying activation of HSC in liver fibrogenesis and the potential therapeutic value of PPAR␥ ligands for liver fibrosis.

There exists a unique group of persons who are able to durably control HIV in the absence of therapy. The mechanisms of control in these persons remain poorly defined. In this study, we examined CD8 ؉ T-cell responses in blood and rectal mucosa from 17 "elite controllers" (viral load < 75 copies/mL), 11 "viremic controllers" (75-2000 copies/mL), 14 noncontrollers (> 10 000 copies/mL), and 10 antiretroviral-treated persons (< 75 copies/mL). Production of interferon-␥, interleukin-

Growth cones are highly polarized and dynamic structures confined to the tips of axons. The polarity of growth cones is in part maintained by suppression of protrusive activity from the distal axon shaft, a process termed axon consolidation. The mechanistic basis of axon consolidation that contributes to the maintenance of growth cone polarity is not clear. We report that inhibition of RhoA-kinase (ROCK) or myosin II resulted in unstable consolidation of the distal axon as evidenced by increased filopodial and lamellipodial extension. Furthermore, when ROCK or myosin II was inhibited lamellipodia formed at the growth cone migrated onto the axon shaft. Analysis of EYFP-actin dynamics in the distal axon revealed that ROCK negatively regulates actin polymerization and initiation of protrusive structures from spontaneously formed axonal F-actin patches, the latter being an effect attributable to ROCK-mediated regulation of myosin II. Inhibition of ROCK or myosin II blocked growth cone turning toward NGF by preventing suppression of protrusive activity away from the source of NGF, resulting in aborted turning responses. These data elucidate the mechanism of growth cone polarity, provide evidence that consolidation of the distal axon is a component of guidance, and identify ROCK as a negative regulator of F-actin polymerization underlying protrusive activity in the distal axon.

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BACKGROUND: Electronic referrals can improve access to subspecialty care in safety net settings. In January 2007, San Francisco General Hospital (SFGH) launched an electronic referral portal that incorporated subspecialist triage, iterative communication with referring providers, and existing electronic health record data to improve access to subspecialty care. OBJECTIVE:We surveyed primary care providers (PCPs) to assess the impact of electronic referrals on workflow and clinical care. DESIGN:We administered an 18-item, web-based questionnaire to all 368 PCPs who had the option of referring to SFGH. MEASUREMENTS:We asked participants to rate time spent submitting a referral, guidance of workup, wait times, and change in overall clinical care compared to prior referral methods using 5-point Likert scales. We used multivariate logistic regression to identify variables associated with perceived improvement in overall clinical care. RESULTS:Two hundred ninety-eight PCPs (81.0%) from 24 clinics participated. Over half (55.4%) worked at hospital-based clinics, 27.9% at county-funded community clinics, and 17.1% at non-county-funded community clinics. Most (71.9%) reported that electronic referrals had improved overall clinical care. Providers from non-county-funded clinics (AOR 0.40, 95% CI 0.14-0.79) and those who spent ≥6 min submitting an electronic referral (AOR 0.33, 95%CI 0.18-0.61) were significantly less likely than other participants to report that electronic referrals had improved clinical care.CONCLUSIONS: PCPs felt electronic referrals improved health-care access and quality; those who reported a negative impact on workflow were less likely to agree. While electronic referrals hold promise as a tool to improve clinical care, their impact on workflow should be considered.KEY WORDS: electronic referral; information technology; subspecialty care; safety net health system. J Gen Intern Med (24)5:614-9

OBJECTIVES Morbidity and mortality due to liver disease and cirrhosis vary significantly by race/ethnicity in the United States. We examined the prevalence of liver disease risk factors among blacks, Mexican Americans, and whites, including elevated aspartate aminotransferase and alanine aminotransferase activity, infection with viral hepatitis B or hepatitis C, alcohol intake, obesity, diabetes, and metabolic syndrome. METHODS Data were obtained from the Fourth National Health and Nutrition Examination Survey (NHANES IV). A logistic regression was used to examine the association of race/ethnicity to liver disease risk factors, controlling for the demographic and socioeconomic variables. RESULTS Mexican-American men and women are the most likely to have elevated aminotransferase activity. Among men, Mexican Americans are more likely than whites to be heavy/binge drinkers, and blacks are more likely to have hepatitis B or hepatitis C. Among women, Mexican Americans are more likely than whites to be obese and diabetic, and less likely to be heavy/binge drinkers; blacks are more likely than whites to have hepatitis B or hepatitis C, be obese or diabetic, and less likely to be heavy/binge drinkers. CONCLUSIONS In this national sample, the prevalence of risk factors for liver disease varies by race/ethnicity. Mexican Americans and blacks have a greater risk of developing liver disease than their white counterparts. These findings are consistent with the observed racial/ethnic disparities in morbidity and mortality due to chronic liver disease and contribute to the efforts to identify the causes of these disparities. This information can be used by health professionals to tailor screening and intervention programs.

A small percentage of human immunodeficiency virus (HIV)-infected individuals, termed elite controllers, are able to spontaneously control HIV replication in blood. As the gastrointestinal mucosa is an important site of HIV transmission and replication as well as CD4؉ T-cell depletion, it is important to understand the nature of the immune responses occurring in this compartment. Although the role of the HIV-specific CD8؉ T-cell responses in mucosal tissues has been described, few studies have investigated the role of mucosal HIV-specific CD4 ؉ T cells. In this study, we assessed HIV-specific CD4 ؉ T-cell responses in the rectal mucosa of 28 "controllers" (viral load [VL] of <2,000 copies/ml), 14 "noncontrollers" (VL of >10,000 copies/ml), and 10 individuals on highly active antiretroviral therapy (HAART) (VL of <75 copies/ml). Controllers had highermagnitude Gag-specific mucosal CD4؉ T-cell responses than individuals on HAART (P < 0. 05), as measured by their ability to produce gamma interferon (IFN-␥), interleukin-2 (IL-2), tumor necrosis factor alpha (TNF-␣), and macrophage inflammatory protein 1␤ (MIP-1␤). The frequency of polyfunctional mucosal CD4 ؉ T cells was also higher in controllers than in noncontrollers or individuals on HAART (P < 0.05). Controllers with the strongest HIV-specific CD4؉ T-cell responses possessed class II HLA alleles, HLA-DRB1*13 and/or HLA-DQB1*06, previously associated with a nonprogression phenotype. Strikingly, individuals with both HLA-DRB1*13 and HLA-DQB1*06 had highly polyfunctional mucosal CD4 ؉ T cells compared to individuals with HLA-DQB1*06 alone or other class II alleles. The frequency of polyfunctional CD4 ؉ T cells in rectal mucosa positively correlated with the magnitude of the mucosal CD8 ؉ T-cell response (Spearman's r ‫؍‬ 0.43, P ‫؍‬ 0.005), suggesting that increased CD4 ؉ T-cell "help" may be important in maintaining strong CD8 ؉ T-cell responses in the gut of HIV controllers.

Growth cone motility and guidance depend on the dynamic reorganization of filamentous actin (F-actin). In the growth cone, F-actin undergoes turnover, which is the exchange of actin subunits from existing filaments. However, the function of F-actin turnover is not clear. We used jasplakinolide (jasp), a cell-permeable macrocyclic peptide that inhibits F-actin turnover, to study the role of F-actin turnover in axon extension. Treatment with jasp caused axon retraction, demonstrating that axon extension requires F-actin turnover. The retraction of axons in response to the inhibition of F-actin turnover was dependent on myosin activity and regulated by RhoA and myosin light chain kinase. Significantly, the endogenous myosin-based contractility was sufficient to cause axon retraction, because jasp did not alter myosin activity. Based on these observations, we asked whether guidance cues that cause axon retraction (ephrin-A2) inhibit F-actin turnover. Axon retraction in response to ephrin-A2 correlated with decreased F-actin turnover and required RhoA activity. These observations demonstrate that axon extension depends on an interaction between endogenous myosin-driven contractility and F-actin turnover, and that guidance cues that cause axon retraction inhibit F-actin turnover.