Screening for hepatitis C in a general adult population in a low-prevalence area: the Tromsø study.

BACKGROUND: Chronic hepatitis C virus (HCV) infection can progress to cirrhosis and end-stage liver disease in a substantial proportion of patients. The infection is frequently asymptomatic, leaving many infected individuals unaware of the diagnosis until complications occur. This advocates the screening of healthy individuals. The aim of this study was to estimate the prevalence of HCV infection in the general adult population of the municipality of Tromsø, Norway, and to evaluate the efficiency of such an approach in a presumed low-prevalence area. METHODS: The study was part of the seventh survey of the Tromsø Study (Tromsø 7) in 2015-2016. Sera from 20,946 individuals aged 40 years and older were analysed for antibodies to HCV (anti-HCV). A positive anti-HCV test was followed up with a new blood test for HCV RNA, and the result of any previous laboratory HCV data were recorded. Samples positive for anti-HCV and negative for HCV RNA were tested with a recombinant immunoblot assay. All HCV RNA positive individuals were offered clinical evaluation. RESULTS: Among 20,946 participants, HCV RNA was detected in 33 (0.2%; 95% CI: 0.1-0.3), of whom 13 (39.4%; 95% CI: 22.7-56.1) were unaware of their infection. The anti-HCV test was confirmed positive in 134 individuals (0.6%; 95% CI: 0.5-0.7) with the highest prevalence in the age group 50-59 years. Current or treatment-recovered chronic HCV-infection was found in 85 individuals (0.4%; 95% CI: 0.3-0.5) and was associated with an unfavorable psychosocial profile. CONCLUSION: In this population-based study, the prevalence of viraemic HCV infection was 0.2%. A substantial proportion (39%) of persons with viraemic disease was not aware of their infectious status, which suggests that the current screening strategy of individuals with high risk of infection may be an inadequate approach to identify chronic HCV infection hidden in the general population.

Leptin to adiponectin ratio - A surrogate biomarker for early detection of metabolic disturbances in obesity.

AIM: To study if the leptin to adiponectin (L:A) ratio, can be a potential biomarker for postprandial triglyceride clearance, insulin resistance (IR) or leptin resistance (LR) in apparently healthy obese, and obese individuals with established metabolic disease. METHODS AND RESULTS: Fifty adult subjects with obesity (BMI ≥30); of which 36 metabolic healthy obese (MHO), and 14 metabolic dysregulated obese (MDO), with clinical and/or biochemical signs of metabolic disease were included. Seventeen healthy, normal weight subjects represented the control group. Postprandial triglyceride (TG) levels were measured in an 8 h oral fat tolerance test (OFTT). IR by HOMA-IR, L:A ratio and indirect LR were measured. In the MHO group, 71.4%, 69.4% and 86.1%, had delayed TG clearance, IR and LR, respectively; whereas in the MDO group this was detected in 85.7%, 71.4% and 91.7%, respectively. A combination of all three metabolic risk factors was found in 39.8% of the MHO and in 42.9% of the MDO patients. Receiver operating characteristics (ROC) analysis revealed that a cut-off value for the L:A ratio of >1.65 for the control group (PPV 1.0, NPV 0.91) and >3.65 for the obese subjects (PPV 0.86, NPV 0.48) predicted the delayed TG clearance with a good specificity and sensitivity. Detecting a combined risk with at least 2/3 metabolic risk factors, the ROC yielded the most suitable L:A ratio cut-off at >1.88. CONCLUSION: L:A ratio was able to detect early metabolic disturbances in obese individuals, and may be a potential useful clinical surrogate biomarker of metabolic disorders.

Future complications of chronic hepatitis C in a low-risk area: projections from the hepatitis c study in Northern Norway.

BACKGROUND: Hepatitis C (HCV) infection causes an asymptomatic chronic hepatitis in most affected individuals, which often remains undetected until cirrhosis and cirrhosis-related complications occur. Screening of high-risk subjects in Northern Norway has revealed a relatively low prevalence in the general population (0.24%). Despite this, late complications of HCV infection are increasing. Our object was to estimate the future prevalence and complications of chronic HCV infection in the period 2013-2050 in a low-risk area. METHODS: We have entered available data into a prognostic Markov model to project future complications to HCV infection. RESULTS: The model extrapolates the prevalence in the present cohort of HCV-infected individuals, and assumes a stable low incidence in the projection period. We predict an almost three-fold increase in the incidence of cirrhosis (68 per 100,000), of decompensated cirrhosis (21 per 100,000) and of hepatocellular carcinoma (4 per 100,000) by 2050, as well as a six-fold increase in the cumulated number of deaths from HCV-related liver disease (170 per 100,000 inhabitants). All estimates are made assuming an unchanged treatment coverage of approximately 15%. The estimated numbers can be reduced by approximately 50% for cirrhosis, and by approximately one third for the other endpoints if treatment coverage is raised to 50%. CONCLUSION: These projections from a low-prevalence area indicate a substantial rise in HCV-related morbidity and mortality in the coming years. The global HCV epidemic is of great concern and increased treatment coverage is necessary to reduce the burden of the disease.

Postprandial leptin and adiponectin in response to sugar and fat in obese and normal weight individuals.

PURPOSE: Adipokines produced by white adipose tissue are central in the development of lifestyle diseases. Individuals in industrialized countries spend a substantial part of life in the non-fasting, postprandial state, which is associated with increased oxidation and inflammation. The aim was to study postprandial adiponectin and leptin levels after an oral fat tolerance test (OFTT) and an oral glucose tolerance test (OGTT) in obese (OB) and healthy, normal weight individuals (NW). METHODS: Fifty adults with obesity (BMI ≥ 30) and 17 healthy, NW were included. Postprandial triglyceride (TG), adiponectin, and leptin levels were measured every second hour during an 8 h OFTT, and every half hour during a 2 h OGTT. RESULTS: Compared with the basal level, postprandial levels of adiponectin following OFTT showed a slight initial peak, followed by a significant decrease at 8 h, in the NW. In the OB these changes were abolished. Postprandial levels of leptin decreased significantly from basal levels in the OFTT, in the NW, whereas in the OB, leptin was unchanged except for a slight increase from 2 to 8 h. During the OGTT both adiponectin and leptin levels remained unchanged in the NW, but decreased significantly in the OB. In addition, the OB had delayed TG clearance at 6 h. CONCLUSIONS: A fatty meal gives postprandial changes in the secretion of adiponectin and leptin in NW, but not in OB. Our observations indicate that a potential postprandial regulatory role of adiponectin and leptin is impaired in OB, and of importance in a more comprehensive understanding of the delayed postprandial TG clearance in obese individuals.

Induction of peroxisomal acyl-CoA oxidase by 3-thia fatty acid, in hepatoma cells and hepatocytes in culture is modified by dexamethasone and insulin.

The effects of tetradecylthioacetic acid (TTA) (50 microM), dexamethasone (0.25 microM) and insulin (0.4 microM) on induction of peroxisomal acyl-CoA oxidase activity and mRNA levels were studied in short term cultures of Morris 7800C1 and MH1C1 hepatoma cells and of rat hepatocytes. Dexamethasone and TTA resulted in parallel increases in the enzyme activity and the steady state mRNA content in the hepatoma cells. Combination of dexamethasone and TTA resulted in a synergistic and parallel stimulation of both the enzyme activity and the mRNA levels up to 11-12-fold and maximal changes were observed after 14 days of treatment. Semiquantitative immunoblot analyses of acyl-CoA oxidase were in concordance with enzyme and mRNA results. Insulin counteracted the inductive effects of dexamethasone and TTA on all parameters. The half-life of the acyl-CoA oxidase mRNA increased after treatment with the 3-thia fatty acid (t1/2 = 10.0 h +/- 0.4) compared to control (t1/2 = 5.9 h +/- 0.3). However, in combination with dexamethasone there was no further increase in the mRNA stability (t1/2 = 8.0 h +/- 0.3). Southern blot analysis did not reveal any changes on the oxidase gene level in any treatment group. TTA alone or in combination with dexamethasone did not affect the expression of either the glucocorticoid receptor or the peroxisomal proliferator acting receptor (PPAR) steady state mRNA levels. In cultured hepatocytes the acyl-CoA oxidase was modified in similar manner by these treatments, but the changes were less marked. We suggest that the changes in peroxisomal acyl-CoA oxidase activity in hepatoma cells are due to a major effect on the level of mRNA, involving both transcriptional effects and message stabilization.

'Cross-talk' between phospholipase C and adenylyl cyclase involves regulation of G-protein levels in GH3 rat pituitary cells.

We have investigated the possibility that adenylyl cyclase (AC) activity and membrane protein levels of the alpha-subunits of the stimulatory and inhibitory G-proteins of AC (Gs alpha and G(i)-2 alpha) in cultured prolactin-producing rat pituitary adenoma cells (GH3 cells) are modulated by phospholipase C (PLC)-generated second messengers. Pretreatment of cells (6-48 h) with ionomycin (1 microM) or 1-oleoyl-2-acetylglycerol (OAG; 1 microM) showed that ionomycin regulated Gs alpha levels in a time-dependent, biphasic manner; a two-fold increase followed a 40% initial reduction, while OAG lowered Gs alpha levels by more than 50% at all time-points. G(i)-2 alpha levels remained unchanged by both pretreatments. OAG, but not ionomycin, increased basal AC activity without increasing enzyme protein levels. Alterations in AC responsiveness to peptide hormones (e.g. thyroliberin and vasoactive intestinal peptide) correlated to membrane Gs protein alpha-subunit content. These results demonstrate the involvement of G-protein translation regulation as one mechanism of 'cross-talk' between the PLC- and AC-dependent signalling pathways.

Signal transduction alterations in GH(1)2C1 rat pituitary tumour cells following treatment with 5-azacytidine.

In GH(1)2C1 rat pituitary cells treated with 5-azacytidine, the stimulatory effects exerted by vasoactive intestinal peptide (VIP), the GTP analogue guanyl-5'-yl imidodiphosphate (Gpp(NH)p), 12-O-tetradecanoyl phorbol 13-acetate, cholera toxin and pertussis toxin on the membrane-bound adenylyl cyclase were almost completely abolished. The corresponding inhibitory effect of somatostatin was increased. Alterations in adenylyl cyclase responsiveness began at the end of the drug treatment, and were most pronounced on day 5 after removal of 5-azacytidine. The cells subsequently and completely recovered after 10 days in the absence of the drug. Measurements of cholera toxin- and VIP-enhanced cyclic AMP levels in intact cells confirmed these results, and VIP appeared to have no stimulatory effect on GH secretion after 5-azacytidine treatment. Down-regulation of G alpha s RNA also occurred on day 5 after cessation of drug treatment. ADP-ribosylation subsequent to stimulation with pertussis toxin was markedly increased, indicating an enhancement of G alpha i and/or G alpha o. Furthermore, both basal and Gpp(NH)p-stimulated phospholipase C activities were augmented by pre-exposure to 5-azacytidine. Treatment of GH(1)2C1 rat pituitary tumour cells with 5-azacytidine therefore causes a marked but temporary increase in the ratio of G alpha i/G alpha s protein levels.

Hypothalamic hormones modulate G protein levels and second messenger responsiveness in GH3 rat pituitary tumour cells.

Thyroliberin (TRH), vasoactive intestinal peptide (VIP) and somatostatin (SRIF) act through receptors that are coupled to guanine nucleotide-binding regulatory proteins (G proteins). Regulation of hormone action may occur at the level of G protein coupling to the receptor or effector systems. In this study we demonstrate that prolonged exposure (for up to 48 hr) of cultured rat pituitary adenoma GH3 cells to these hormones caused homologous and to some extent heterologous attenuation of the adenylyl cyclase (AC) (EC 4.6.1.1) responsiveness. In addition, TRH and SRIF diminished both TRH- and guanosine 5'-[beta gamma-imido]-triphosphate-enhanced phospholipase C (PLC) (EC 3.1.4.3) activity within the same time-course. Measurements of cells membrane levels of Gs protein alpha-subunit (Gs alpha), G(i)-1 alpha/G(i)-2 alpha, G(i)-3 alpha, G(o) alpha and G beta by immunoblotting were performed. TRH and VIP upregulated levels of all G proteins except G(o) alpha and G beta. In contrast, SRIF caused a marked reduction of G beta levels. Thus, TRH and VIP, both acting through Gs, both modulated the alpha-subunit levels of this signal transducer, whereas SRIF, which possibly acts through G(i)-2, did not change the steady state level of G(i)-2 alpha. The actions of TRH, VIP and SRIF are multifaceted at the G protein level, where modulations of subtypes not directly involved in their actions may occur. These findings emphasize the complexity expected to be found in the in vivo situation.

Cell specific distribution of guanine nucleotide-binding regulatory proteins in rat pituitary tumour cell lines.

To investigate the effects of guanine nucleotide-binding regulatory proteins (G proteins) on hormonal regulation of prolactin (PRL) synthesis and secretion, the qualitative distribution of G protein alpha-subunits and their mRNAs was studied in three functionally different pituitary tumour cell lines (GH cells) and normal rat pituitary tissue. Levels of basal and modulated adenylyl cyclase (AC) and phospholipase C (PLC) activities are also included. GH cells and pituitary tissue contained various amounts of mRNAs and protein for Gs alpha, Gi-2 alpha, Gi-3 alpha and Go alpha, while mRNA for Gi-1 alpha was only detected in normal pituitary tissue. Gz alpha/Gx alpha mRNA was expressed in all pituitary cell lines as well as in pituitary tissue. Go alpha mRNA and Gz alpha/G x alpha mRNA displayed size heterogeneity. These findings may have importance in the understanding of hormone regulation of second messenger systems.

G-proteins: implications for pathophysiology and disease.

This article focuses on the involvement of G-proteins in neuroendocrine secretion, cell growth and phenotype alterations. The current concept of hormonal activation of the GTPase cycle, as well as the molecular diversity of G-proteins families and receptor*G-protein*effector coupling, are described. Also described are certain G-proteins as possible proto-oncogenes and how point mutations and frame shift mutations alter G-protein function and determine the characteristics of various endocrine diseases. The article outlines in detail how receptors and G-proteins interact in prolactin and growth-hormone-secreting pituicytes, how G-proteins are involved in the growth and differentiation of preadipocytes and osteoblasts. All in all, it seems that hormonal activation through G-proteins is modulated through direct intra- and inter-signalling system cross-talk at the plasma membrane level (short-term) and through interactions on the level of transcription (HREs) from tyrosine kinases, steroid-like hormones and metabolic pathways. Pharmacological intervention to treat diseases where G-proteins are involved should take both long and short-term regulatory phenomena into consideration.