Protein phosphatases and their potential implications in neuroprotective processes

Abstract.: Several neurological disorders such as stroke, amyotrophic lateral sclerosis and epilepsy result from excitotoxic events and are accompanied by neuronal cell death. These processes engage multiple signalling pathways and recruit numerous molecular components, in particular several families of protein kinases and protein phosphatases. While many investigations have examined the importance of protein kinases in excitotoxicity, protein phosphatases have not been well studied in this context. However, recent advances in understanding the functions of protein phosphatases have suggested that they may play a neuroprotective role. In this review, we summarize some of the recent findings that illustrate the pleiotropic and complex functions of tyrosine and serine/threonine protein phosphatases in the cascade of events leading to neuronal cell death, and highlight their potential intervention in limiting the extent of neuronal deat

Consistency of pacing and metabolic responses during 2000-m rowing ergometry

PURPOSE: This study investigated the pacing strategy adopted and the consistency of performance and related physiological parameters across three 2000-m rowing-ergometer tests. METHODS: Fourteen male well-trained rowers took part in the study. Each participant performed three 2000-m rowing-ergometer tests interspersed by 3-7 d. Throughout the trials, respiratory exchange and heart rate were recorded and power output and stroke rate were analyzed over each 500 m of the test. At the completion of the trial, assessments of blood lactate and rating of perceived exertion were measured. RESULTS: Ergometer performance was unchanged across the 3 trials; however, pacing strategy changed from trial 1, which featured a higher starting power output and more progressive decrease in power, to trials 2 and 3, which were characterized by a more conservative start and an end spurt with increased power output during the final 500 m. Mean typical error (TE; %) across the three 2000-m trials was 2.4%, and variability was low to moderate for all assessed physiological variables (TE range = 1.4-5.1%) with the exception of peak lactate (TE = 11.5%). CONCLUSIONS: Performance and physiological responses during 2000-m rowing ergometry were found to be consistent over 3 trials. The variations observed in pacing strategy between trial 1 and trials 2 and 3 suggest that a habituation trial is required before an intervention study and that participants move from a positive to a reverse-J-shaped strategy, which may partly explain conflicting reports in the pacing strategy exhibited during 2000-m rowing-ergometer trials

Expanding the therapeutic repertoire of epidermal growth factor receptor blockade: radiosensitization

Expression of epidermal growth factor receptor (EGFR) has been associated with radioresistance in cancer. Moreover, tumour cell recovery after irradiation paradoxically occurs, in part, as a result of activation of EGFR signalling by such treatment. A recent article by Huang, Li, Armstrong and Harari provides strong rationale for considering the anti-EGFR agent ZD1839 ('Iressa') as a radiosensitizing strategy. With the use of several in vitro and xenograft models of human squamous cell head and neck carcinoma, ZD1939 was shown to markedly improve radiotherapeutic response, with superior tumour inhibition and delayed tumour regrowth. Mechanisms underlying this effect included anti-proliferative and pro-apoptotic activity, with significant perturbation of tumour angiogenesis

Vitamin D deficiency: awareness and practice

Within the UK rickets is emerging as a national public health issue, particularly among at-risk groups. There is concern that health professionals are overlooking recommendations for vitamin supplementation and opportunities for prevention. This paper reports on a study that aimed to identify current knowledge and practice regarding vitamin D deficiency and supplementation among community midwifery and health visiting teams employed in one NHS trust. A questionnaire was distributed to all health visiting and community midwifery team members (n=96), with a 76% response rate (n=73). Results suggest varying levels of awareness about vitamin D deficiency and groups at increased risk. Only 52% reported that they were aware of health department recommendations for vitamin supplementation. Health visiting teams recommended supplements more frequently than community midwives, but overall the recommendations were implemented inconsistently. Participants identified families eligible for the government Healthy Start scheme, but fewer were recommending Healthy Start vitamins. A deeper understanding of vitamin D deficiency and health department recommendations for vitamin supplementation is required by health professionals to ensure families are advised about appropriate prevention messages and to implement recommendations effectively. Key words: Vitamin D deficiency, rickets, Healthy Start, vitamin supplements, health departmen

Learning the game: Breakdowns, breakthroughs and player strategies

Digital games are rich learning environments that require players to engage with challenging situations in order to progress. Recent research indicates that game-play involves overcoming breakdowns and achieving breakthroughs in relation to player action, understanding and involvement. In particular, breakthroughs involve moments of insight where learning occurs which, in turn, can help increase involvement. However, little is known about how players actually achieve breakthroughs. We applied the breakdown/breakthrough “lens” to explore how players attempt to achieve breakthroughs in relation to two single player games. We identified a finite number of strategies that illustrate how players learn in games. These strategies are considered in relation to producing playable and engaging games

Nearly 85% of tobacco smoke is invisible - a confirmation of previous claims

Contributors The original concept for the article came from AC, when researching the provenance of the claim that 85% of tobacco smoke is invisible. ILG led both the data analysis and the drafting of the paper with significant contributions from SS and AW. All contributors reviewed and edited the final manuscript. Ivan Gee is the guarantor for the article

Is treatment for alcohol use disorder associated with reductions in criminal offending? A national data linkage cohort study in England.

BACKGROUND: This is the first English national study of change in criminal offending following treatment for alcohol use disorder (AUD). METHODS: All adults treated for AUD by all publicly funded treatment services during April 2008-March 2009 (n=53,017), with data linked to the Police National Computer (April 2006-November 2011). Pre-treatment offender sub-populations were identified by Latent Profile Analysis. The outcome measure was the count of recordable criminal offences during two-year follow-up after admission. A mixed-effects, Poisson regression modelled outcome, adjusting for demographics and clinical information, the latent classes, and treatment exposure covariates. RESULTS: Twenty-two percent of the cohort committed one or more offences in the two years pre-treatment (n=11,742; crude rate, 221.5 offenders per 1000). During follow-up, the number of offenders and offences fell by 23.5% and 24.0%, respectively (crude rate, 69.4 offenders per 1000). During follow-up, a lower number of offences was associated with: completing treatment (adjusted incident rate ratio [IRR] 0.82; 95% confidence interval [CI] 0.79-0.85); receiving inpatient detoxification (IRR 0.84; CI 0.80-0.89); or community pharmacological therapy (IRR 0.89; CI 0.84-0.96). Reconviction was reduced in the sub-population characterised by driving offences (n=1,140; 11.7%), but was relatively high amongst acquisitive (n=768; 58.3% reconvicted) and violent offending sub-populations (n=602; 77.6% reconvicted). CONCLUSIONS: Reduced offending was associated with successful completion of AUD treatment and receiving inpatient and pharmacological therapy, but not enrolment in psychological and residential interventions. Treatment services (particularly those providing psychological therapy and residential care) should be alert to offending, especially violent and acquisitive crime, and enhance crime reduction interventions

Loss of oestrogen receptor alpha in long-term antioestrogen-resistant cells: reversal by a c-src inhibitor

Background Tamoxifen still remains the most frequently used antioestrogen for the treatment of breast cancer. However, its efficacy is often limited by the emergence of acquired resistance and it has been suggested that, in some instances, this may involve oestrogen receptor (ER) loss. This study addresses this issue by examining long-term tamoxifen treatment of breast cancer cells and identifies that progressive ER loss does occur, leading to greatly increased aggressive tumour cell behaviour. Encouragingly, even after 30 months treatment, ER loss is reversible by a c-src inhibitor. Our data therefore provide a new model to study the cellular mechanisms associated with antihormone promoted ER loss and its possible prevention/reversal by signal transduction inhibitors. Methods Using quantitative PCR based on SYBR Green fluorescence, the expression of total ERα mRNA and its constituent mRNA variants were quantified in MCF7 cells and in our in vitro developed tamoxifen-resistant breast cancer cells (TamR), which have been cultured in the presence of tamoxifen for 30 months. Specific PCR amplification of all ERα mRNA variants was possible using forward primers designed to bind specifically to the 5' untranslated regions of ERα mRNA and used separately with a common reverse primer that anneals to the 5' end of the protein encoding region of exon 1 of ERα cDNA. Expression of ERα protein was assessed by western blot and immunohistochemistry. Results In MCF7 cells, the ERα mRNA isoforms A, B and C were detected as the most predominant variants, with C ERα mRNA showing the highest expression level. In TamR cells, about a 40% fall in total ERα mRNA was observed in comparison with MCF7 cells and was most apparent for the C variant. Extension of the tamoxifen treatment period to 30 months produced a further dramatic decrease in ERα mRNA (all variants) and protein levels, resulting in ER negativity being recorded in >90% of the cells by immunohistochemistry. These cells show increased levels of phosphorylated Erk 1&2, AKT, PKCα and src, and are highly aggressive in their growth behaviour, with increased cell motility and invasiveness. Treatment of the cells with the demethylating agent 5-azacytidine did not restore ERα expression, suggesting that epigenetic alterations are unlikely to be responsible for the reduced ER levels. However, Affymetrix data in the TamR cells showed that some positive regulators of ER expression, such as p53 and Foxo3A, are downregulated during the development of the resistant phenotype and their continued absence may contribute to the progressive ER loss. Significantly, pathway inhibitor studies revealed c-src to be an important regulator of ER loss, since its inhibition rapidly restored ER levels. Conclusion Our data indicate that considerable ER loss can occur during antihormonal treatment of breast cancer cells and that this can lead to a more aggressive phenotype. Encouragingly, however, even after 30 months exposure to tamoxifen, the process is reversible by inhibition of c-src. These data suggest that combinations of antihormones with signal transduction inhibitors could retain ER functions in treated cells and prevent a drift towards more aggressive cancer cell behaviour

Tamoxifen, 17beta-oestradiol and the calmodulin antagonist J8 inhibit human melanoma cell invasion through fibronectin.

Invasion through stromal extracellular matrix (ECM) is part of the complex, multistep process of tumour cell invasion and metastasis. Our group has previously demonstrated that calcium and calmodulin are important in another step in the metastatic cascade - that of attachment of cells to ECM. Interestingly, the non-steroidal anti-oestrogen tamoxifen (which also has calmodulin antagonist activity), used in the treatment of breast cancer and now in metastatic cutaneous melanoma, can inhibit the attachment of normal and neoplastic cells to ECM. In this study, we investigated whether such drugs, known to inhibit cell attachment, could also subsequently reduce their invasion through a layer of human fibronectin. We examined the ability of the specific calmodulin antagonist J8, tamoxifen and its two major metabolites, N-desmethyltamoxifen (N-des) and 4-hydroxytamoxifen (4-OH), as well as the pure anti-oestrogen ICI 182,780 and 17beta-oestradiol to inhibit invasion of the human cutaneous melanoma cell line, A375-SM, uveal melanoma cells and uveal melanocytes. A375-SM cells and uveal melanoma cells showed a high level of invasion (15.2% and 33.7% respectively) compared with melanocytes (around 5%) under the experimental conditions used. Submicromolar concentrations of N-des, tamoxifen, J8 and 17beta-oestradiol significantly reduced the invasiveness of the A375-SM cell line. The uveal melanoma cells also showed similar inhibition, although at higher concentrations of these agents. 4-OH and ICI 182, 780 had little or no effect on invasion of A375-SM cells (these were not tested on uveal melanoma cells). All cells used in this study were found to be negative for type I nuclear oestrogen receptors, reinforcing the possibility that tamoxifen and 17beta-oestradiol can act via mechanisms unrelated to binding to classical oestrogen receptors to inhibit tumour cell invasion

Knowledge of and Adherence to Health Advice among Adults with Diabetes in Libya

Background: Non-adherence to medical and health care advice is a common problem, though reasons for non-adherence can differ across different groups and societies as well as between individuals. Objective: to examine diabetes knowledge among people with both type1 and type2 diabetes in Libya and explore any other factors that enhance adherence to treatment and management of the condition. Methods: A cross-sectional survey design was used to collect data from adults with type1 or type2 diabetes who have been diagnosed for 12 months or more, in Benghazi Diabetes Centre, which is one of the oldest and largest diabetes registries in Libya. A total of 855 participants were asked to fill in two questionnaires; the Michigan Diabetes Knowledge Test to investigate the level of diabetes knowledge and the Confidence in diabetes Self-care Scale to assess self-efficacy. For the purpose of the study descriptive statistics and inferential statistical tests were conducted. Results: Diabetes knowledge is very poor especially among females and those classed as illiterate within the sample. The Mean HbA1c of 9.39 was higher than the recommended levels. Four variables namely knowledge about diabetes, duration of illness, family history and self-efficacy significantly predicted levels of HBA1c. Conclusion: Based on the above findings two different programmes of diabetes education would be recommended. The first programme of education would focus primarily on those with inadequate levels of knowledge about diabetes, particularly female and people with long duration diabetes. The second programme would be for both healthcare professionals and people with type 1 and type2 diabetes, which would consider the psychological factors that are involved in the process of diabetes management