Virus-induced over-expression of protein phosphatase 2A inhibits insulin signalling in chronic hepatitis C

BACKGROUND/AIMS: Hepatitis C virus (HCV) infection disturbs glucose and lipid metabolism contributing to the development of liver steatosis, insulin resistance and type 2 diabetes mellitus. On the other hand, insulin resistance and steatosis have been found to be associated with increased rates of fibrosis progression and lower rates of response to interferon therapy in chronic hepatitis C (CHC). The molecular mechanisms contributing to insulin resistance in CHC are not well understood. We have shown previously that protein phosphatase 2A (PP2A) is over-expressed in biopsies from patients with CHC. In this study, we tested if PP2A over-expression leads to insulin resistance. METHODS: We studied insulin signalling in cell lines that allow the regulated over-expression of HCV proteins and of the PP2A catalytic subunit (PP2Ac). Insulin signalling and PP2Ac expression were also studied in HCV transgenic mice and in liver biopsies from patients with CHC. RESULTS: Over-expression of PP2Ac in cells inhibited insulin signalling by dephosphorylation of PKB/Akt. PP2Ac over-expression and impaired insulin signalling were found in the liver of HCV transgenic mice and in liver biopsies of patients with CHC. CONCLUSIONS: HCV-induced over-expression of PP2A in the liver contributes to the pathogenesis of insulin resistance in patients with CHC.     

The hsp27kD heat shock protein and p38-MAPK signaling are required for regular epidermal differentiation

Background

In human epidermal keratinocytes the expression of hsp27 is closely related to differentiation in vitro and in situ.

Objective

We aimed to gain further insight into the role of hsp27 in epidermal differentiation by specific inhibition through siRNA and inhibition of p38-MAPK, the key enzyme of hsp27 phosphorylation.

Methods

Normal human keratinocytes (KC) and organotypic skin cultures (SE-skin equivalents) were used. Expression and phosphorylation of hsp27 was inhibited in these models by siRNA and SB203580, a specific inhibitor of p38-MAPK, respectively. Modification of morphology and expression of hsp27 and other differentiation associated proteins was investigated by immunofluorescence, western blot, and RT-PCR.

Results

Inhibition of p38-MAPK resulted in a downregulation of hsp27 in KC and SE. Additionally, in the presence of SB203580 Ca²⁺ induced expression of pro-filaggrin and loricrin was inhibited at the protein level and expression of filaggrin, keratin 10, and transglutaminase 1 at the mRNA level. Addition of SB203580 to SE, as well as hsp27 knockdown in this model resulted in identical patterns of irregular differentiation, disturbance of epidermal layers, and delayed expression of K10.

Conclusion

These results provide evidence that the expression of hsp27 and its phosphorylation by p38-MAPK are required for keratinocyte differentiation and for the formation of a regularly stratified epidermis.     

A mitochondrial myopathy in an infant with lactic acidosis

We describe a girl with mitochondrial myopathy, who presented with general muscle weakness, muscle hypotonia and motor retardation. The level of blood lactate and pyruvate was consistently increased. Enzymatic studies showed impairment of NADH-dehydrogenase activity (complex I of the respiratory chain) in skeletal muscle. Electron-microscopy of a muscle biopsy showed abnormalities of a mitochondrial myopathy. The girl, now aged 30 months, has been treated with riboflavine (vitamin B2) since the age of 14 months, and lactate and pyruvate levels have decreased to normal. The patient still shows mild muscle hypotonia and weakness, but good motor progress and normal cognitive development.     

Selective increase of in vivo firing frequencies in DA SN neurons after proteasome inhibition in the ventral midbrain

The impairment of protein degradation via the ubiquitin‐proteasome system (UPS) is present in sporadic Parkinson's disease (PD), and might play a key role in selective degeneration of vulnerable dopamine (DA) neurons in the substantia nigra pars compacta (SN). Further evidence for a causal role of dysfunctional UPS in familial PD comes from mutations in parkin, which results in a loss of function of an E3‐ubiquitin‐ligase. In a mouse model, genetic inactivation of an essential component of the 26S proteasome lead to widespread neuronal degeneration including DA midbrain neurons and the formation of alpha‐synuclein‐positive inclusion bodies, another hallmark of PD. Studies using pharmacological UPS inhibition in vivo had more mixed results, varying from extensive degeneration to no loss of DA SN neurons. However, it is currently unknown whether UPS impairment will affect the neurophysiological functions of DA midbrain neurons. To answer this question, we infused a selective proteasome inhibitor into the ventral midbrain in vivo and recorded single DA midbrain neurons 2 weeks after the proteasome challenge. We found a selective increase in the mean in vivo firing frequencies of identified DA SN neurons in anesthetized mice, while those in the ventral tegmental area (VTA) were unaffected. Our results demonstrate that a single‐hit UPS inhibition is sufficient to induce a stable and selective hyperexcitability phenotype in surviving DA SN neurons in vivo. This might imply that UPS dysfunction sensitizes DA SN neurons by enhancing ‘stressful pacemaking’.     

Life satisfaction and active coping style are important predictors of recovery from surgery

OBJECTIVE: The objectives of this study were to investigate the influence of psychological factors on the recovery of surgical patients and to explore whether there are any psychological variables other than anxiety that have a significant influence on recovery from surgery. METHODS: The participants were 112 adult patients undergoing a variety of surgical procedures. On the day prior to surgery, the Freiburg Personality Questionnaire, the State-Trait Anxiety Inventory, a coping schedule and the Questionnaire of Social Support were used to measure psychological parameters including personality, anxiety, coping and social support. The quality of the surgical outcome was rated by two independent and blinded surgeons by the length of hospital stay and analgesia and sedation requirements. The ratings controlled for the diagnosis, type of operation, intraoperative complications, postoperative medical problems and health limitations independent of the surgical procedure. RESULTS: Patients who had a complicated recovery were found to have reduced life satisfaction and lower situation-specific self-control expectations. Structural equation modeling revealed direct relationships between recovery from surgery and personality dimensions with the strongest correlations to life satisfaction, extraversion and attainment orientation. CONCLUSION: The data from this study suggests that valid predictions of the course of postoperative recovery need to take into account personality and coping behaviour orientated data as well as clinical variables. No direct influence on recovery could be predicted from preoperative state anxiety, but it seems likely that state anxiety may influence coping behaviour and that it is this that appears to have a significant impact to surgical recovery.     

Right heart function in impaired left ventricular diastolic function: 2D speckle tracking echocardiography–based and Doppler tissue imaging–based analysis of right atrial and ventricular function

Aim

The aim of our study was to describe right atrial (RA) and right ventricular (RV) function, assessed by Doppler tissue imaging and 2D speckle tracking echocardiography (2DSTE), in women with signs of early impaired left ventricular diastolic function (DD).

Methods and Results

In a cross‐sectional trial, standard parameters of diastolic and right heart function were investigated in 438 women of the Berlin Female Risk Evaluation (BEFRI) study. In a subset of women, average peak systolic RA strain (RAS), as well as the average peak systolic RV strain of the free wall (RVS free wall) and of all RV segments (average RV strain; RVS Avg), was analyzed using 2DSTE. Compared to women with normal diastolic function (DD0), RAS, RVS free wall and RVS Avg were significantly reduced in DD (43.1% ± 11.9%, ?26.7% ± 5.6%, and ?23.3% ± 3.5% in DD0; vs 35.1% ± 10.4%, ?23.9% ± 5.5%, and ?20.6% ± 3.8% in DD; P < .01). Peak RV myocardial velocity (RV‐IVV) and acceleration during isovolumetric contraction (RV‐IVA) were markedly higher in DD (15.0 ± 3.9 cm/s and 3.1 ± 1.0 m/s² in DD vs 11.9 ± 3.2 cm/s and 2.8 ± 0.8 m/s² in DD0; P < .05). RAS and RV‐IVV were significantly associated with DD after adjustment to age, BMI, and left atrial strain in multivariate regression analysis.

Conclusion

Systolic right heart function is significantly altered in DD. DTI as well as 2DSTE constitute sensitive echocardiographic tools that enable the diagnosis of impaired right heart mechanics in early‐staged DD.     

Randomized comparison of reduced fat and reduced carbohydrate hypocaloric diets on intrahepatic fat in overweight and obese human subjects

Obesity-related hepatic steatosis is a major risk factor for metabolic and cardiovascular disease. Fat reduced hypocaloric diets are able to relieve the liver from ectopically stored lipids. We hypothesized that the widely used low carbohydrate hypocaloric diets are similarly effective in this regard. A total of 170 overweight and obese, otherwise healthy subjects were randomized to either reduced carbohydrate (n = 84) or reduced fat (n = 86), total energy restricted diet (-30% of energy intake before diet) for 6 months. Body composition was estimated by bioimpedance analyses and abdominal fat distribution by magnetic resonance tomography. Subjects were also submitted to fat spectroscopy of liver and oral glucose tolerance testing. In all, 102 subjects completed the diet intervention with measurements of intrahepatic lipid content. Both hypocaloric diets decreased body weight, total body fat, visceral fat, and intrahepatic lipid content. Subjects with high baseline intrahepatic lipids (>5.56%) lost ≈7-fold more intrahepatic lipids compared with those with low baseline values (<5.56%) irrespective of diet composition. In contrast, changes in visceral fat mass and insulin sensitivity were similar between subgroups, with low and high baseline intrahepatic lipids. CONCLUSION: A prolonged hypocaloric diet low in carbohydrates and high in fat has the same beneficial effects on intrahepatic lipid accumulation as the traditional low-fat hypocaloric diet. The decrease in intrahepatic lipids appears to be independent of visceral fat loss and is not tightly coupled with changes in whole body insulin sensitivity during 6 months of an energy restricted diet.     

Ethnopharmacological in vitro studies on Austria's folk medicine—An unexplored lore in vitro anti-inflammatory activities of 71 Austrian traditional herbal drugs

Ethnopharmacological relevance

In Austria, like in most Western countries, knowledge about traditional medicinal plants is becoming scarce. Searching the literature concerning Austria's ethnomedicine reveals its scant scientific exploration.Aiming to substantiate the potential of medicinal plants traditionally used in Austria, 63 plant species or genera with claimed anti-inflammatory properties listed in the VOLKSMED database were assessed for their in vitro anti-inflammatory activity.

Material and methods

71 herbal drugs from 63 plant species or genera were extracted using solvents of varying polarities and subsequently depleted from the bulk constituents, chlorophylls and tannins to avoid possible interferences with the assays. The obtained 257 extracts were assessed for their in vitro anti-inflammatory activity. The expression of the inflammatory mediators E-selectin and interleukin-8 (IL-8), induced by the inflammatory stimuli tumor necrosis factor alpha (TNF-α) and the bacterial product lipopolysaccharide (LPS) was measured in endothelial cells. The potential of the extracts to activate the nuclear factors PPARα and PPARγ and to inhibit TNF-α-induced activation of the nuclear factor-kappa B (NF-κB) in HEK293 cells was determined by luciferase reporter gene assays.

Results

In total, extracts from 67 of the 71 assessed herbal drugs revealed anti-inflammatory activity in the applied in vitro test systems. Thereby, 30 could downregulate E-selectin or IL-8 gene expression, 28 were strong activators of PPARα or PPARγ (inducing activation of more than 2-fold at a concentration of 10 µg/mL) and 21 evoked a strong inhibition of NF-κB (inhibition of more than 80% at 10 µg/mL).

Conclusion

Our research supports the efficacy of herbal drugs reported in Austrian folk medicine used for ailments associated with inflammatory processes. Hence, an ethnopharmacological screening approach is a useful tool for the discovery of new drug leads.