Background

Complications of hepatitis C virus (HCV) infection are primarily related to the development of advanced fibrosis.

Methods

Baseline data from a prospective community-based cohort study of 204 persons with chronic hepatitis C virus (HCV) infection were used for analysis. The outcome was fibrosis score on biopsy and the primary predictor evaluated was daily cannabis use.

Results

The median age of the cohort was 46.8 years, 69.1% were male, 49.0% were Caucasian, and the presumed route of infection was injection drug use in 70.1%. The median lifetime duration and average daily use of alcohol were 29.1 years and 1.94 drink equivalents per day. Cannabis use frequency (within prior 12 months) was daily in 13.7%, occasional in 45.1%, and never in 41.2%. Fibrosis stage, assessed by Ishak method, was F0, F1–2 and F3–6 in 27.5%, 55.4% and 17.2% of subjects, respectively. Daily compared to non-daily cannabis use was significantly associated with moderate to severe fibrosis (F3–6 versus F1–2) in univariate [OR = 3.21 (95% CI, 1.20–8.56), p = 0.020] and multivariate analyses (OR = 6.78, (1.89–24.31), p=0.003). Other independent predictors of F3–6 were ≥11 portal tracts (compared to <5, OR = 6.92 (1.34–35.7), p=0.021] and lifetime duration of moderate and heavy alcohol use [OR per decade = 1.72 (1.02–2.90), p=0.044].

Conclusion

We conclude that daily cannabis use is strongly associated with moderate to severe fibrosis and that HCV-infected individuals should be counseled to reduce or abstain from cannabis use.

Background & Aims

Data are conflicting on the benefit of selective serotonin reuptake inhibitors (SSRIs) for patients with irritable bowel syndrome (IBS); the role of visceral sensitivity in IBS pathophysiology is unclear. We assessed the effects of citalopram and the relationships between, symptoms, and quality of life (QOL), and rectal sensitivity in non-depressed patients with IBS.

Methods

Patients from primary, secondary and tertiary care centers were randomly assigned to groups given citalopram (20 mg/day for 4 weeks, then 40 mg/day for 4 weeks) or placebo. The study was double masked with concealed allocation. Symptoms were assessed weekly; IBS-QOL and rectal sensation were determined from barostat measurements made at the beginning and end of the study.

Results

Patients that received citalopram did not have a higher rate of adequate relief from IBS symptoms than subjects that received placebo (12/27, 44% vs 15/27, 56% respectively; P=0.59), regardless of IBS subtype. The odds ratio for weekly response to citalopram vs placebo was 0.80 (95% confidence interval [CI] 0.61–1.04). Citalopram did not reduce specific symptoms or increase IBS-QOL scores; it had no effect on rectal compliance and a minimal effect on sensation. Changes in IBS-QOL score and pressure-eliciting pain were correlated (r=0.33, 95% CI 0.03–0.57); changes in symptoms and rectal sensitivity or IBS-QOL scores were not correlated.

Conclusions

Citalopram was not superior to placebo in treating non-depressed IBS patients. Changes in symptoms were not correlated with changes in rectal sensation assessed by barostat; Any benefit of citalopram in non-depressed IBS patients is likely to be modest.

To determine the association of self-perceived fat gain or fat loss in central and peripheral body sites with adherence to highly active antiretroviral therapy (HAART) in HIV-seropositive women. 1,671 women from the Women’s Interagency HIV Study who reported HAART use between April 1999 and March 2006 were studied. Adherence was defined as report of taking HAART ≥ 95% of the time during the prior 6 months. Participant report of any increase or decrease in the chest, abdomen, or upper back in the prior 6 months defined central fat gain and central fat loss, respectively. Report of any increase or decrease in the face, arms, legs or buttocks in the prior 6 months defined peripheral fat gain or peripheral fat loss. Younger age, being African-American (vs. White non-Hispanic), a history of IDU, higher HIV RNA at the previous visit, and alcohol consumption were significant predictors of HAART non-adherence (P <0.05). After multivariate adjustment, self-perception of central fat gain was associated with a 1.5-fold increased odds of HAART non-adherence compared to no change. Perception of fat gain in the abdomen was the strongest predictor of HAART non-adherence when the individual body sites were studied. Women who perceive central fat gain particularly in the abdomen are at risk for decreased adherence to HAART despite recent evidence to suggest that HIV and specific antiretroviral drugs are more commonly associated with fat loss than fat gain.

Connexin43 (Cx43) is the most abundantly expressed gap junction protein. The C-terminal tail of Cx43 is important for regulation of gap junctions via phosphorylation of specific tyrosine and serine residues and through interactions with cellular proteins. The C-terminus of Cx43 has been shown to interact with the PDZ2 domain of the tight and adherens junction associated zona occludens 1 (ZO-1) protein. Analysis of the PDZ2 binding domain of Cx43 indicated that positions −3 and −2, and the final hydrophobic amino acid at the C-terminus, are critical for ZO-1 binding. In addition, the C-termini of connexins 40 and 45, but not Cx32, interacted with ZO-1. To evaluate the functional significance of the Cx43-ZO-1 interaction, Cx43 wild type (Cx43wt) and mutants lacking either the C-terminal hydrophobic isoleucine (Cx43ΔI382) or the last five amino acids (Cx43Δ378–382), required for ZO-1 binding in vitro, were introduced into a Cx43-deficient MDCK cell line. In vitro binding studies and coimmunoprecipitation assays indicated that these Cx43 mutants failed to interact with ZO-1. Confocal and deconvolution microscopy revealed that a fraction of Cx43wt colocalized with ZO-1 at the plasma membrane. A similar colocalization pattern was observed for the Cx43ΔI382 and Cx43Δ378–382 mutants, which were translocated to the plasma membrane and formed functional gap junction channels. The wt and mutant Cx43 appeared to have similar turnover rates. However, the P2 and P3 phosphoisoforms of the Cx43 mutants were significantly reduced compared to Cx43wt. These studies indicated that the interaction of Cx43 with ZO-1 may contribute to the regulation of Cx43 phosphorylation.

The degradation of connexin43 (Cx43) has been reported to involve both lysosomal and proteasomal degradation pathways; however, very little is known about the mechanisms regulating these Cx43 degradation pathways. Using yeast two-hybrid, glutathione S-transferase pull-down, and co-immunoprecipitation approaches, we have identified a novel Cx43-interacting protein of ~75 kDa, CIP75. Laser confocal microscopy showed that CIP75 is located primarily at the endoplasmic reticulum, as indicated by the calnexin marker, with Cx43 co-localization in this perinuclear region. CIP75 belongs to the UbL (ubiquitin-like)-UBA (ubiquitin-associated) domain-containing protein family with a N-terminal UbL domain and a C-terminal UBA domain. The UBA domain of CIP75 is the main element mediating the interaction with Cx43, whereas the CIP75-interacting region in Cx43 resides in the PY motif and multiphosphorylation sites located between Lys264 and Asn302. Interestingly, the UbL domain interacts with the S2/RPN1 and S5a/RPN10 protein subunits of the regulatory 19 S proteasome cap subunit of the 26 S proteasome complex. Overexpression experiments suggested that CIP75 is involved in the turnover of Cx43 as measured by a significant stimulation of Cx43 degradation and reduction in its half-life with the opposite effects on Cx43 degradation observed in small interference RNA knockdown experiments.

Connexin43 (Cx43) is a membrane-spanning protein that forms channels that bridge the gap between adjacent cells and this allows for the intercellular exchange of information. Cx43 is regulated by phosphorylation and by interacting proteins. “Mode-1” interaction with 14-3-3 requires phosphorylation of Ser373 on Cx43 (Park et al. 2006). Akt phosphorylates and targets a number of proteins to interactions with 14-3-3. Here we demonstrate that Akt phosphorylates Cx43 on Ser373 and Ser369; antibodies recognizing Akt-phosphorylated sites or phospho-Ser “mode-1” 14-3-3-binding sites recognize a protein from EGF-treated cells that migrates as Cx43, and GST-14-3-3 binds to Cx43 phosphorylated endogenously in EGF-treated cells. Confocal microscopy supports the co-localization of Cx43 with Akt and with 14-3-3 at the outer edges of gap junctional plaques. These data suggest that Akt could target Cx43 to an interaction with 14-3-3 that may play a role in the forward trafficking of Cx43 multimers and/or their incorporation into existing gap junctional plaques.

Gap junctions play critical roles in tissue function and homeostasis. Connexin43 (Cx43) is a major gap junction protein expressed in the mammalian heart and other tissues and may be regulated by its interaction with other cellular proteins. Using the yeast two-hybrid screen, we identified a novel Cx43-interacting protein of 85-kDa, CIP85, which contains a single TBC, SH3, and RUN domain, in addition to a short coiled coil region. Homologues containing this unique combination of domains were found in human, D. melanogaster, and C. elegans. CIP85 mRNA is expressed ubiquitously in mouse and human tissues. In vitro interaction assays and in vivo co-immunoprecipitation experiments confirmed the interaction of endogenous CIP85 with Cx43. In vitro interaction experiments using CIP85 mutants with in-frame deletions of the TBC, SH3, and RUN domains indicated that the SH3 domain of CIP85 is involved in its interaction with Cx43. Conversely, analysis of Cx43 mutants with proline to alanine substitutions in the two proline-rich regions of Cx43 revealed that the P253LSP256 motif is an important determinant of the ability of Cx43 to interact with CIP85. Laser-scanning confocal microscopy showed that CIP85 colocalized with Cx43 at the cell periphery, particularly in areas reminiscent of gap junction plaques. The functional importance of the interaction between CIP85 and Cx43 was suggested by the observation that CIP85 appears to induce the turnover of Cx43 through the lysosomal pathway.