Effect of continuous positive airway pressure treatment on serum cardiovascular risk factors in patients with obstructive sleep apnea-hypopnea syndrome.

BACKGROUND: Serum levels of circulating markers associated with cardiovascular morbidity are elevated in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). These factors are studied in patients mainly before the application of therapy with continuous positive airway pressure (CPAP), and the effects of CPAP treatment on them have not been thoroughly studied. Therefore, the aim of the study was to examine the effect of compliance to CPAP therapy on these factors. METHODS: Patients with newly diagnosed OSAHS, nonsmokers, without comorbidities or medication use, at baseline and during the follow-up period, were included. Serum cardiovascular risk factors (ie, high-sensitivity C-reactive protein [hs-CRP], homocysteine, total cholesterol, triglycerides, high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol, apolipoprotein A-I [ApoA-I], and apolipoprotein B [ApoB]) were measured at baseline and 6 months after CPAP application. Patients were classified into the following three groups according to CPAP use: group 1 (n = 20), good compliance (>or= 4 h use per night); group 2 (n = 19), poor compliance (< 4 h use per night); and group 3 (n = 14), refusal of CPAP treatment. RESULTS: Fifty-three patients (47 male patients and 6 female patients; mean [+/- SD] age, 46.09 +/- 10.87 years) were included in the study. In all groups, body mass index remained stable. In group 1, significant decreases in the levels of hs-CRP (p = 0.03), homocysteine (p = 0.005), total cholesterol (p = 0.021), total cholesterol/HDL-C ratio (p = 0.018), and ApoB/ApoA-I ratio (p = 0.021) was observed. The patients in group 2 showed a decrease in homocysteine levels (p = 0.021) only, while no significant changes were observed in the patients in group 3. CONCLUSIONS: Good compliance to CPAP treatment lowers the serum levels of cardiovascular risk factors, indicating a beneficial effect on the overall cardiovascular risk.

Metabolic studies of hepatocytes cultured on collagen substrata modified to contain glycosaminoglycans.

Bioartificial liver devices replace the function of the failing liver, using primary hepatocytes cultured in a bioreactor module. Most devices have been based on cartridge designs, but alternative designs using monolayers of cells in a flat plate bioreactor may be more efficacious. Collagen coating improves the maintenance of hepatocytes on polymeric membranes, and in this article the effect of contact with glycosaminoglycans (GAGs) on the function of hepatocytes was assessed. The effect of two different GAGs, chondroitin-6-sulfate and heparin, in the presence and absence of a cross-linking agent (1,6-diaminohexane [DAH]), on the activities of two major metabolic pathways in hepatocytes (cytochrome P-450-dependent monooxygenase activity, assessed by the hydroxylation of testosterone, and UDP-glucuronosyltransferase activity, assessed by the glucuronidation of kaempferol) cultured on collagen gels and films is presented. Testosterone metabolism was more extensive in cells cultured on collagen films than in cells cultured on gels. The addition of heparin and DAH to collagen gels supported the formation of 6beta-hydroxy, 16alpha-hydroxy, and 2alpha-hydroxy testosterone by cells cultured for 48 h. The extent of glucuronidation of kaempferol was not different when comparing cells cultured on films or gels at the various times in culture; however, the ratio of formation of the two glucuronides formed, M1 and M2, was different. The combination of chondroitin- 6-sulfate and DAH increased glucuronidation of cells cultured for 7 days on both collagen films and gels. This approach may increase the expression of hepatocyte-specific functions in monolayers cultured on membranes in flat plate bioreactors.

The influence of glycosaminoglycans and crosslinking agents on the phenotype of hepatocytes cultured on collagen gels.

The use of primary hepatocyte cultures as in vitro models for studying xenobiotic metabolism and toxicity is limited by the loss of liver-specific differentiated functions with time in culture and the inability of the cells to proliferate. The aim of this study was to investigate the effect of incorporating 20% chondroitin-6-sulphate (Ch6SO4), a glycosaminoglycan (GAG), into collagen gels (0.3% w/v) and crosslinking the gels with either 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) or 1,6-diaminohexane (DAH) on the expression of glutathione-S-transferases (GSTs) and the activity of cytochrome P450 in hepatocytes cultured for 48 hours and 7 days. Hepatocytes were isolated from male Sprague-Dawley rats by collagenase perfusion. Cell homogenates were immunoblotted against class alpha and pi GST subunits. To measure cytochrome P450 activity, testosterone hydroxylation was assessed. Viability of the cultured cells was assessed by confocal laser scanning microscopy using the vital stain carboxyfluorescein diacetate (CFDA). Cells cultured on gels crosslinked with EDAC were dead by 48 hours as judged by lack of CFDA-derived fluorescence and absence of GST bands on the immunoblots. The viability and morphology of the cells were unaffected by any of the other components of the substrata tested. Expression of GSTs indicated that the hepatocyte phenotype was stable for at least 48 hours. The addition of GAG did not improve the phenotype at either 48 hours or 7 days in culture, but the combination of GAG and DAH crosslinking improved GST expression in the 7-day cultures. However, the hepatocyte cytochrome P450 activity did not show any improvement on any of the gels. The combination of GAG and DAH crosslinking provided the most stable substratum environment in terms of GST expression in hepatocytes.