Publications

TGF-β promotes excessive collagen deposition in fibrotic diseases such as idiopathic pulmonary fibrosis (IPF). The amino acid composition of collagen is unique due to its high (33%) glycine content. Here, we report that TGF-β induces expression of glycolytic genes and increases glycolytic flux. TGF-β also induces the expression of the enzymes of the de novo serine synthesis pathway (phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase 1 (PSAT1), and phosphoserine phosphatase (PSPH)) and de novo glycine synthesis (serine hydroxymethyltransferase 2 (SHMT2)). Studies in fibroblasts with genetic attenuation of PHGDH or SHMT2 and pharmacologic inhibition of PHGDH showed that these enzymes are required for collagen synthesis. Furthermore, metabolic labeling experiments demonstrated carbon from glucose incorporated into collagen. Lungs from humans with IPF demonstrated increased expression of PHGDH and SHMT2. These results indicate that the de novo serine synthesis pathway is necessary for TGF-β-induced collagen production and suggest that this pathway may be a therapeutic target for treatment of fibrotic diseases including IPF.

OBJECTIVE

Out-of-network emergency department (ED) use, or use that occurs outside the contracted network, may lead to increased care fragmentation and cost. We examined factors associated with out-of-network ED use among Medicaid beneficiaries.

DATA SOURCES AND STUDY SETTING

Enrollment, claims, and encounter data for adult Medi-Cal health plan members with 1+ ED visits and complete Medicaid eligibility during the study period from 2013 to 2014.

STUDY DESIGN

We analyzed the data to identify factors associated with out-of-network ED use classified by mode of arrival (ambulance vs. nonambulance).

DATA EXTRACTION METHODS

We extracted encounter, ambulance, and ED census data and linked them together based on ED visit date.

PRINCIPAL FINDINGS

Of 11,143 ED visits, 6,808 (61.1 percent) were out-of-network. The number of hours the study ED was on ambulance diversion increased the odds of out-of-network visits for the 3,365 (30.2 percent) ED visits arriving by ambulance. For all visit types, assignment to a primary care clinic at the in-network hospital and having had any primary care visit during the study period decreased the odds of out-of-network ED care. Individuals were more likely to go out-of-network for ED care if they lived in neighborhoods containing out-of-network EDs.

CONCLUSIONS

There are a number of factors related to out-of-network ED use, including the proximity and density of out-of-network EDs, race and ethnicity, a prior history of out-of-network ED use, and individuals' connection to primary care. EDs that serve Medicaid beneficiaries may need to explore alternative sites and modalities of care as alternatives to the ED, and consider their ability to absorb large numbers of out-of-network visits given already limited capacity.

UNLABELLED

Hepatitis C virus (HCV) is unique among RNA viruses in its ability to establish chronic infection in the majority of exposed adults. HCV persists in the liver despite interferon (IFN)-stimulated gene (ISG) induction; robust induction actually predicts treatment failure and viral persistence. It is unclear which forms of HCV RNA are associated with ISG induction and IFN resistance during natural infections. To thoroughly delineate HCV RNA populations, we developed conditions that fully separate the strands of long double-stranded RNA (dsRNA) and allow the released RNAs to be quantified in reverse transcription/polymerase chain reaction assays. These methods revealed that dsRNA, a pathogen-associated molecular pattern (PAMP), comprised 52% (standard deviation, 28%) of the HCV RNA in the livers of patients with chronic infection. HCV dsRNA was proportionally higher in patients with the unfavorable IL28B TT (rs12979860) genotype. Higher ratios of HCV double-stranded to single-stranded RNA (ssRNA) correlated positively with ISG induction. In Huh-7.5 cells, IFN treatment increased the total amount of HCV dsRNA through a process that required de novo viral RNA synthesis and shifted the ratio of viral dsRNA/ssRNA in favor of dsRNA. This shift was blocked by ribavirin (RBV), an antiviral drug that reduces relapse in HCV patients. Northern blotting established that HCV dsRNA contained genome-length minus strands.

CONCLUSION

HCV dsRNA is the predominant form in the HCV-infected liver and has features of both a PAMP and a genomic reservoir. Interferon treatment increased rather than decreased HCV dsRNA. This unexpected finding suggests that HCV produces dsRNA in response to IFN, potentially to antagonize antiviral defenses. (Hepatology 2017;66:357-370).