Impact of direct-acting antiviral treatment of hepatitis C on the quality of life of adults in Ukraine.

BACKGROUND: Direct-acting antivirals (DAAs) are highly effective in achieving sustained virologic response among those with chronic hepatitis C virus (HCV) infection. Quality of life (QOL) benefits for an HCV-infected population with high numbers of people who inject drugs and people living with HIV (PLHIV) in Eastern Europe have not been explored. We estimated such benefits for Ukraine. METHODS: Using data from a demonstration study of 12-week DAA conducted in Kyiv, we compared self-reported QOL as captured with the MOS-SF20 at study entry and 12 weeks after treatment completion (week 24). We calculated domain scores for health perception, physical, role and social functioning, mental health and pain to at entry and week 24, stratified by HIV status. RESULTS: Among the 857 patients included in the final analysis, health perception was the domain that showed the largest change, with an improvement of 85.7% between entry and week 24. The improvement was larger among those who were HIV negative (104.4%) than among those living with HIV (69.9%). Other domains that showed significant and meaningful improvements were physical functioning, which improved from 80.5 (95% CI 78.9-82.1) at study entry to 89.4 (88.1-90.7) at 24 weeks, role functioning (64.5 [62.3-66.8] to 86.5 [84.9-88.2]), social functioning (74.2 [72.1-76.2] to 84.8 [83.2-86.5]) and bodily pain (70.1 [68.2-72.0] to 89.8 [88.5-91.1]). Across all domains, QOL improvements among PLHIV were more modest than among HIV-negative participants. CONCLUSION: QOL improved substantially across all domains between study entry and week 24. Changes over the study period were smaller among PLHIV.

Heme maintains catalytically active structure of cytochrome P-450.

Treatment of purified cytochrome P-450 LM2 and its liposome-bound form with hydrogen peroxide led to complete destruction of the P-450 heme. The apoenzyme thus produced could be reconstituted to catalytically active cytochrome P-450 by incubation with hemin, the reconstitution efficiency being 50% for the soluble enzyme and 80% for the liposome-bound enzyme. The removal of heme from the soluble hemoprotein resulted in a 3-fold decrease in the efficiency of its incorporation into sonicated liposomes. The contents of 5 secondary structure forms in the native, apo- and reconstituted holoenzymes were estimated from their circular dichroism spectra. It was thus found that the helix content increased from 34% to 60% upon removal of the heme from the native enzyme. We suggest that the increase in the helix content leads to a reduction of the incorporation efficiency into liposomal membranes.

Secondary structure and membrane topology of cytochrome P450s.

The secondary structure prediction of 19 microsomal cytochrome P450s from two different families was made on the basis of their amino acid sequences. It was shown that there is structural similarity between the heme-binding sites in these enzymes and those in the bacterial P450cam. An average predicted secondary structure of cytochrome P450 proteins with 70% accuracy contains about 46% alpha-helices, 12% beta-sheets, 9% beta-turns, and 33% random coils. In the region of residues 35-120 in microsomal P450s two adjacent beta alpha beta-units (the Rossmann domain), were recognized and may be available to interact with the NADPH-cytochrome P450 reductase. Using the procedure for identification of hydrophobic and membrane-associated alpha-helical segments, only one N-terminal transmembrane anchor was predicted. Also the heme-binding site may include the surface-bound helix. A model for vertebrate microsomal P450s having an amphipathic membrane protein located on the cytoplasmic side of the endoplasmic reticulum membrane, with their active center lying outside or on the bilayer border, is proposed.

Effect of the microenvironment on the tertiary structure of cytochrome P-450 LM2.

The relation between microenvironment and the tertiary structure of cytochrome P-450 LM2 has been investigated. No complete relaxation to the most active state of the native enzyme took place in the case of membrane-incorporated hemoprotein with three or four intramolecular cross-links. The spatial organization of the enzyme was predicted to determine the cross-link location on the hemoprotein surface and membrane-incorporated parts of the polypeptide chain. It was concluded on the basis of the predicted structure that hemoprotein has an amphipathic structure and, thus, the greater part of molecule is exposed to the water phase. Not more than one NH2-terminal alpha helix is able to incorporate into the membrane. The location of this region is believed to control the formation of the catalytically-active-conformational state of cytochrome P-450 LM2.