Factors associated with HCV test uptake in heroin users entering substitution treatment in Greece.

OBJECTIVES: People who inject drugs (PWID) represent the main risk group for hepatitis C virus (HCV) infection in most middle and high-income countries. Testing PWID is considered as an important prevention measure. Identification of PWID characteristics associated with HCV testing may contribute to strategies targeting the containment of the HCV and HIV epidemics in Greece. METHODS: Anonymous behavioural data from 2747 heroin users were collected upon entry in 38 opioid substitution treatment (OST) clinics in Greece during the period 2013-2015. HCV test uptake was the dependent variable while covariates included sociodemographic and addiction-related variables, mostly derived from the EMCDDA treatment demand indicator protocol. RESULTS: Among 2299 cases with complete data on HCV testing, 83.5% reported any HCV testing uptake, with 61.2% reporting a recent test (< 12 months). In the multivariate analyses, any previous HCV testing uptake was associated with age ≥ 25 years, past drug treatment attempt, injecting or sniffing the primary substance, injection history ≥ 5 years, and syringe sharing earlier than the past 12 months. Past HCV test uptake was higher among those reporting full-time employment and 2-4 years injecting histories, and lower among residents of Athens. Recent testing was positively associated with female gender and polysubstance use. CONCLUSION: Any previous HCV testing uptake is high among PWID entering OST in Greece and is associated with older age, longer injecting histories and past drug-related treatment attempts. Efforts to prevent and mitigate the ongoing HCV test epidemic among PWID in Greece should combine treatment with scaling up of screening, targeting especially those younger than 25 years and at the beginning of their hazardous use.

Involvement of calyculin A inhibitable protein phosphatases in the cyclic AMP signal transduction pathway of mouse corticotroph tumour (AtT20) cells.

1. The role of non-calcineurin protein phosphatases in the cyclic AMP signal transduction pathway was examined in mouse pituitary corticotroph tumour (AtT20) cells. 2. Blockers of protein phosphatases, calyculin A and okadaic acid, were applied in AtT20 cells depleted of rapidly mobilizable pools of intracellular calcium and activated by various cyclic AMP generating agonists. Inhibitors of cyclic nucleotide phosphodiesterases were present throughout. The accumulation of cyclic AMP was monitored by radioimmunoassay, phosphodiesterase activity in cell homogenates was measured by radiometric assay. 3. Neither calyculin A nor okadaic acid altered basal cyclic AMP levels but cyclic AMP formation induced by 41 amino acid residue corticotrophin releasing-factor (CRF) was strongly inhibited (up to 80%), 1-Norokadaone was inactive. Similar data were also obtained when isoprenaline or pituitary adenylate cyclase activating peptide1-38 were used as agonists. 4. Pertussis toxin did not modify the inhibition of CRF-induced cyclic AMP production by calyculin A. 5. Pretreatment with calyculin A completely prevented the stimulation of cyclic AMP formation by cholera toxin even in the presence of 0.5 mM isobutylmethylxanthine (IBMX) and 0.1 mM rolipram. Cholera toxin mediated ADP-ribosylation of the 45 K and 52 K molecular weight Gs alpha isoforms in membranes from calyculin A-pretreated cells was enhanced to 150-200% when compared with controls. 6. Cholera toxin-induced cyclic AMP was reduced by calyculin A within 10 min when calyculin A was applied after a 90 min pretreatment with cholera toxin. Under these conditions the effect of calyculin A could be blocked by the combination of 0.5 mM IBMX and 0.1 mM rolipram, but not by 0.5 mM IBMX alone. 7. Phosphodiesterase activity in AtT20 cell homogenates showed a significant, 2.7 fold increase after treatment with calyculin A. In control cells phosphodiesterase activity was blocked by 80% in the presence of IBMX (0.5 mM), or IBMX plus rolipram (0.1 mM). In calyculin A-treated cells phosphodiesterase activity was also strongly inhibited by IBMX, but because of the stimulating effect of calyculin A, the activity remaining was still 55% of that found in control homogenates. This activity was reduced to 5% of control by using IBMX and rolipram in combination. Assay of phosphodiesterase in Ca2+ free conditions showed that calyculin A markedly increases the activity of rolipram sensitive (type 4) phosphodiesterase. 8. Taken together, blockers of protein phosphatases (PPases) impaired signal transduction through Gs-mediated pathways and activated cyclic AMP degrading phosphodiesterase(s), indicating that PPases 1 and/or 2A are essential for agonist-mediated regulation of cyclic AMP levels in AtT20 cells, and are thus important in maintaining the secretory phenotype of the cells.

The renin-aldosterone axis in patients with diabetes insipidus.

OBJECTIVE: The objective of the present study was to investigate the renin-aldosterone axis in neurogenic diabetes insipidus in man, in view of the fact that profound abnormalities of this axis have been described in experimental animals with congenital neurogenic diabetes insipidus. DESIGN AND PATIENTS: Nine patients with neurogenic diabetes insipidus and 11 healthy subjects (controls) were examined under basal conditions, following the standard 8-hour water deprivation test and 1 hour after a subsequent oral rehydration. MEASUREMENTS: Plasma and urine osmolalities were determined by freezing point depression, plasma sodium and potassium by a method using an ion-selective electrode, plasma AVP, cortisol, aldosterone and plasma renin activity by radioimmunoassay. RESULTS: Plasma renin activities under basal conditions were significantly higher in patients with diabetes insipidus than in controls (mean +/- SEM 23.4 +/- 6.6 vs 7.8 +/- 1.2 ng/l min). In the diabetes insipidus group, water deprivation caused a twofold increase in plasma renin activities (48 +/- 13.8 ng/l min) while in the control group plasma renin activity levels were not significantly altered (10.2 +/- 1.2 ng/l min). Rehydration did not alter plasma renin activity levels in either group (patients 50.4 +/- 13.2, controls 9.0 +/- 2.4 ng/l min). Plasma aldosterone concentrations under basal conditions did not differ between the two groups (patients 302.4 +/- 37, controls 326.4 +/- 36.5 pmol/l) and did not change in patients with diabetes insipidus after water deprivation or rehydration (307.5 +/- 67.2 and 385.5 +/- 91 pmol/l, respectively). Conversely, controls showed a significant decrease in plasma aldosterone levels after dehydration (201 +/- 27.9 pmol/l), which was attributed to the circardian variation in aldosterone secretion, as shown by a parallel decrease in plasma cortisol levels. CONCLUSIONS: Patients with diabetes insipidus are hyper-reninaemic, probably because of chronic volume contraction. There is a dissociation between renin and aldosterone in patients with diabetes insipidus under basal conditions, which is exaggerated during water deprivation.