Depuration of anthropogenic particles by Pacific oysters (Crassostrea gigas): Feasibility and efficacy.

Anthropogenic particles (APs) generated from both natural and synthetic materials are widespread in the aquatic environment and contaminate seafood products, including shellfish. Depuration, involving the placement of filter-feeding shellfish in clean water for a period of time, often several days, is used to reduce contaminant concentrations, but the practicality of its use by the shellfish industry for APs has not yet been examined. In the present study, cultured adult Pacific oysters (Crassostrea gigas) were depurated for 10 days in a facility with limited airflow and filtered seawater. On average, there was a 73 % reduction in oyster AP concentration after 5 days, but no further reduction at 10 days, potentially due to the difficulty in depurating some particles or to re-contamination from the experimental environment. Long-term feasibility for industry will depend on future guidelines for safe AP consumption levels and the practicality and financial feasibility of creating and running clean facilities.

Modelling ocean acidification effects with life stage-specific responses alters spatiotemporal patterns of catch and revenues of American lobster, Homarus americanus.

Ocean acidification (OA) affects marine organisms through various physiological and biological processes, yet our understanding of how these translate to large-scale population effects remains limited. Here, we integrated laboratory-based experimental results on the life history and physiological responses to OA of the American lobster, Homarus americanus, into a dynamic bioclimatic envelope model to project future climate change effects on species distribution, abundance, and fisheries catch potential. Ocean acidification effects on juvenile stages had the largest stage-specific impacts on the population, while cumulative effects across life stages significantly exerted the greatest impacts, albeit quite minimal. Reducing fishing pressure leads to overall increases in population abundance while setting minimum size limits also results in more higher-priced market-sized lobsters (> 1 lb), and could help mitigate the negative impacts of OA and concurrent stressors (warming, deoxygenation). However, the magnitude of increased effects of climate change overweighs any moderate population gains made by changes in fishing pressure and size limits, reinforcing that reducing greenhouse gas emissions is most pressing and that climate-adaptive fisheries management is necessary as a secondary role to ensure population resiliency. We suggest possible strategies to mitigate impacts by preserving important population demographics.

Size and shape matter: A preliminary analysis of microplastic sampling technique in seawater studies with implications for ecological risk assessment.

Microplastic particles (MPs) are widely distributed in seawater. Fibrous MPs (microfibres) are often reported as the most commonly encountered shape of particle. To estimate MP concentrations in seawater, samples are often collected using towed nets (generally 300-350-µm mesh) and may underestimate the amount of microfibres present, which may pass through the mesh due to their narrow width. We compared the potential microplastic particle (PMP) concentration estimates provided by two different seawater sampling methods conducted at three commercial shellfish farms and three unfarmed sites in Baynes Sound, British Columbia, Canada. The methods were: 10-L bucket samples sieved through 63-µm mesh in situ and subsequently filtered through an 8-µm polycarbonate membrane; and 1-L bulk samples collected in jars and subsequently filtered to 8 µm. The jar samples yielded PMP concentrations averaging approximately 8.5 times higher than the bucket samples per L of water (at the site level), largely driven by differences in the number of microfibres. There was no significant difference in PNP concentration between shellfish farms and unfarmed sites. An analysis of MP concentrations and mesh sizes reported in the literature suggests that using a 300-350-µm mesh may underestimate total MP concentrations by one to four orders of magnitude compared with samples that are filtered through much smaller mesh sizes (e.g. <100 µm), despite the effect of sample volume. Particles <300 µm in diameter make up a large component of MPs commonly found in fish and invertebrates. As such, common sampling practices fail to adequately measure a biologically relevant class of MPs, thereby undermining the ability to quantify ecological risk. We suggest that seawater sampling methods be designed to filter to <10 µm (the approximate width of many microfibres), either using pressurized pumps for large-volume samples, or by using sufficient replication of small-volume discrete samples.

Development of human electrophysiological brain networks.

Functional activity in the human brain is intrinsically organized into independently active, connected brain regions. These networks include sensorimotor systems, as well as higher-order cognitive networks such as the default mode network (DMN), which dominates activity when the brain is at rest, and the frontoparietal (FPN) and salience (SN) networks, which are often engaged during demanding tasks. Evidence from functional magnetic resonance imaging (fMRI) suggests that although sensory systems are mature by the end of childhood, the integrity of the FPN and SN develops throughout adolescence. There has been little work to corroborate these findings with electrophysiology. Using magnetoencephalography (MEG) recordings of 48 participants (aged 9-25 yr) at rest, we find that beta-band functional connectivity within the FPN, SN, and DMN continues to increase through adolescence, whereas connectivity in the visual system is mature by late childhood. In contrast to fMRI results, but replicating the MEG findings of Schäfer et al. (Schäfer CB, Morgan BR, Ye AX, Taylor MJ, Doesburg SM. Hum Brain Mapp 35: 5249-5261, 2014), we also see that connectivity between networks increases rather than decreases with age. This suggests that the development of coordinated beta-band oscillations within and between higher-order cognitive networks through adolescence might contribute to the developing abilities of adolescents to focus their attention and coordinate diverse aspects of mental activity. NEW & NOTEWORTHY Using magnetoencephalography to assess beta frequency oscillations, we show that functional connectivity within higher-order cognitive networks increases from childhood, reaching adult values by age 20 yr. In contrast, connectivity within a primary sensory (visual) network reaches adult values by age 14 yr. In contrast to functional MRI findings, connectivity between cognitive networks matures at a rate similar to within-network connectivity, suggesting that coordination of beta oscillations both within and between networks is associated with maturation of cognitive skills.

Altered temporal stability in dynamic neural networks underlies connectivity changes in neurodevelopment.

Network connectivity is an integral feature of human brain function, and characterising its maturational trajectory is a critical step towards understanding healthy and atypical neurodevelopment. Here, we used magnetoencephalography (MEG) to investigate both stationary (i.e. time averaged) and rapidly modulating (dynamic) electrophysiological connectivity, in participants aged from mid-childhood to early adulthood (youngest participant 9 years old; oldest participant 25 years old). Stationary functional connectivity (measured via inter-regional coordination of neural oscillations) increased with age in the alpha and beta frequency bands, particularly in bilateral parietal and temporo-parietal connections. Our dynamic analysis (also applied to alpha/beta oscillations) revealed the spatiotemporal signatures of 8 dynamic networks; these modulate on a ∼100 ms time scale, and temporal stability in attentional networks was found to increase with age. Significant overlap was found between age-modulated dynamic networks and inter-regional oscillatory coordination, implying that altered network dynamics underlie age related changes in functional connectivity. Our results provide novel insights into brain network electrophysiology, and lay a foundation for future work in childhood disorders.

Programmes for advance distribution of misoprostol to prevent post-partum haemorrhage: a rapid literature review of factors affecting implementation.

Recent efforts to prevent post-partum haemorrhage (PPH) in low-income countries have focused on providing women with access to oral misoprostol during home birth. The WHO recommends using lay health workers (LHWs) to administer misoprostol in settings where skilled birth attendants are not available. This review synthesizes current knowledge about the barriers and facilitators affecting implementation of advance community distribution of misoprostol to prevent PPH, where misoprostol may be self-administered or administered by an LHW.We searched for and summarized available empirical evidence, and collected primary data from programme stakeholders about their experiences of programme implementation.We present key outcomes and features of advanced distribution programmes that are in operation or have been piloted globally. We categorized factors influencing implementation into those that operate at the health system level, factors related to the community and policy context and those factors more closely connected to the end user.Debates around advance distribution have centred on the potential risks and benefits of making misoprostol available to pregnant women and community members during pregnancy for administration in the home. However, the risks of advance distribution appear manageable and the benefits of self-administration, especially for women who have little chance of expert care for PPH, are considerable.

Giving women their own case notes to carry during pregnancy.

BACKGROUND: In many countries women are given their own case notes to carry during pregnancy to increase their sense of control over, and satisfaction with, their care. OBJECTIVES: To evaluate the effects of giving women their own case notes to carry during pregnancy. SEARCH METHODS: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 August 2015) and reference lists of retrieved studies. SELECTION CRITERIA: Randomised controlled trials of women given their own case notes to carry during pregnancy. DATA COLLECTION AND ANALYSIS: Two review authors independently applied the inclusion criteria and assessed study quality. One review author extracted data from the included studies using a standard form (checked by second review author). We assessed estimates of effect using risk ratio (RR) with 95% confidence intervals (CI). The quality of the evidence was assessed using the GRADE approach. MAIN RESULTS: Four trials were included (n = 1176 women). Overall, the quality of the evidence was graded as low to moderate mainly due to the nature of the intervention not allowing blinding. The updated search identified one cluster-randomised trial, which was included.Women carrying their own notes were more likely to feel in control (two trials, RR 1.56, 95% CI 1.18 to 2.06; 450 women; moderate quality evidence), although there is no evidence of difference in women's satisfaction (two trials, average RR 1.09, 95% CI 0.92 to 1.29); 698 women; low quality evidence). More women in the case notes group wanted to carry their own notes in a subsequent pregnancy (three trials, RR 1.79, 95% CI 1.57 to 2.03; 552 women; low quality evidence). Overall, the pooled estimate of the two trials (n = 347) that reported on the risk of notes lost or left at home was not significant (average RR 0.38, 95% CI 0.04 to 3.84). There was no evidence of difference for health-related behaviours (cigarette smoking and breastfeeding (moderate quality evidence)), analgesia needs during labour (low quality evidence), maternal depression, miscarriage, stillbirth and neonatal deaths (moderate quality evidence). More women in the case notes group had operative deliveries (one trial, RR 1.83, 95% CI 1.08 to 3.12; 212 women), and caesarean sections (one trial, average RR 1.51, 95% CI 1.10 to 2.08; 501 women; moderate quality evidence). AUTHORS' CONCLUSIONS: The four trials are small, and not all of them reported on all outcomes. The results suggest that there are both potential benefits (increased maternal control and increased availability of antenatal records during hospital attendance) and harms (more operative deliveries). Importantly, all of the trials report that more women in the case notes group would prefer to carry their antenatal records in another pregnancy. There is insufficient evidence on health-related behaviours (smoking and breastfeeding), women's satisfaction, and clinical outcomes. It is important to emphasise that this review shows a lack of evidence of benefit rather than evidence of no benefit.

Detection of a parasitic amoeba (Order Dactylopodida) in the female gonads of oysters in Brazil.

The impacts of oocyte parasites on the reproductive success of molluscs are largely unknown. In this study, we evaluated the presence of gonad parasites in 6 species of marine bivalve molluscs native to southern Brazil. Cultured bivalves included the mangrove oyster Crassostrea gasar (sometimes called C. brasiliana), the brown mussel Perna perna, the lion's paw scallop Nodipecten nodosus and the wing pearl oyster Pteria hirundo. Another species of mangrove oyster, C. rhizophorae, and the carib pointed venus clam Anomalocardia brasiliana (syn. A. flexuosa) were collected from the wild. Molluscs were collected in winter 2009 and summer 2010 for histopathological and molecular evaluation. An unknown ovarian parasite (UOP) was observed in histopathological sections of female gonads of C. gasar and C. rhizophorae. The UOP possessed features suggestive of amoebae, including an irregular outer membrane, frothy cytoplasm, a nucleus with a prominent central nucleolus and a closely associated basophilic parasome. PCR analysis was negative for Marteilioides chungmuensis, Perkinsus spp. and Paramoeba perurans. However, real-time PCR successfully amplified DNA from oyster gonads when using universal Paramoeba spp. primers. Also, conventional PCR amplified DNA using primers specific for Perkinsela amoebae-like organisms (syn. Perkinsiella), which are considered as endosymbionts of Parameoba spp., previously thought to be the parasome. Our results suggest that this UOP is a species of amoeba belonging to 1 of the 2 families of the order Dactylopodida, possibly related to Paramoeba spp. This study represents the first report of this type of organism in oysters. We found that C. gasar and C. rhizophorae were the most susceptible molluscs to these UOPs.

Understanding careseeking for child illness in sub-Saharan Africa: a systematic review and conceptual framework based on qualitative research of household recognition and response to child diarrhoea, pneumonia and malaria.

Diarrhoea, pneumonia and malaria are the largest contributors to childhood mortality in sub-Saharan Africa. While supply side efforts to deliver effective and affordable interventions are being scaled up, ensuring timely and appropriate use by caregivers remains a challenge. This systematic review synthesises qualitative evidence on the factors that underpin household recognition and response to child diarrhoea, pneumonia and malaria in sub-Saharan Africa. For this review, we searched six electronic databases, hand searched 12 journals from 1980 to 2010 using key search terms, and solicited expert review. We identified 5104 possible studies and included 112. Study quality was appraised using the Critical Appraisal Skills Program (CASP) tool. We followed a meta-ethnographic approach to synthesise findings according to three main themes: how households understand these illnesses, how social relationships affect recognition and response, and how households act to prevent and treat these illnesses. We synthesise these findings into a conceptual model for understanding household pathways to care and decision making. Factors that influence household careseeking include: cultural beliefs and illness perceptions; perceived illness severity and efficacy of treatment; rural location, gender, household income and cost of treatment. Several studies also emphasise the importance of experimentation, previous experience with health services and habit in shaping household choices. Moving beyond well-known barriers to careseeking and linear models of pathways to care, the review suggests that treatment decision making is a dynamic process characterised by uncertainty and debate, experimentation with multiple and simultaneous treatments, and shifting interpretations of the illness and treatment options, with household decision making hinging on social negotiations with a broad variety of actors and influenced by control over financial resources. The review concludes with research recommendations for tackling remaining gaps in knowledge.

Factors influencing the provision of public health services by village doctors in Hubei and Jiangxi provinces, China.

PROBLEM: The Chinese central government launched the Health System Reform Plan in 2009 to strengthen disease control and health promotion and provide a package of basic public health services. Village doctors receive a modest subsidy for providing public health services associated with the package. Their beliefs about this subsidy and providing public health services could influence the quality and effectiveness of preventive health services and disease surveillance. APPROACH: To understand village doctors' perspectives on the subsidy and their experiences of delivering public health services, we performed 10 focus group discussions with village doctors, 12 in-depth interviews with directors of township health centres and 4 in-depth interviews with directors of county-level Centers for Disease Control and Prevention. LOCAL SETTING: The study was conducted in four counties in central China, two in Hubei province and two in Jiangxi province. RELEVANT CHANGES: Village doctors prioritize medical services but they do their best to manage their time to include public health services. The willingness of township health centre directors and village doctors to provide public health services has improved since the introduction of the package and a minimum subsidy, but village doctors do not find the subsidy to be sufficient remuneration for their efforts. LESSONS LEARNT: Improving the delivery of public health services by village doctors is likely to require an increase in the subsidy, improvement in the supervisory relationship between village clinics and township health centres and the creation of a government pension for village doctors.

Résumé PROBLÈME: Le gouvernement central chinois a lancé le plan de réforme du système de santé en 2009 pour renforcer la lutte contre les maladies et l'amélioration de la santé, et pour fournir un paquet de services de base en termes de santé publique. Les médecins de village reçoivent une subvention modeste pour offrir des services de santé publique liés à ce paquet. Leurs opinions sur cette subvention et la fourniture de services de santé publique pourraient avoir une influence sur la qualité et l'efficacité des services de santé préventive et sur la surveillance des maladies. APPROCHE: Pour comprendre les perspectives des médecins de village sur la subvention et leur expérience dans le domaine de la fourniture de services de santé publique, nous avons organisé 10 discussions de groupe cible avec des médecins de village, 12 entrevues approfondies avec des directeurs de centres de santé cantonaux et 4 entrevues approfondies avec des directeurs départementaux de centres pour la lutte et la prévention des maladies. ENVIRONNEMENT LOCAL: L'étude a été effectuée dans quatre comtés du centre de la Chine, deux dans la province de Hubei et deux dans la province du Jiangxi. CHANGEMENTS SIGNIFICATIFS: Les médecins de village donnent la priorité aux services médicaux, mais ils font de leur mieux pour gérer leur temps de manière à inclure les services de santé publique. La volonté des directeurs de centres de santé cantonaux et des médecins de village d'offrir des services de santé publique s'est accrue depuis l'introduction du paquet et d'une subvention minimale, mais les médecins de village ne considèrent pas que cette subvention constitue une rémunération suffisante pour leurs efforts. LEÇONS TIRÉES: Il est possible que l'amélioration de la fourniture de services de santé publique par les médecins de village nécessite une augmentation de la subvention, l'amélioration de la relation de supervision entre cliniques de village et centres de santé cantonaux et la création d'une pension gouvernementale pour les médecins de village.

Resumen SITUACIÓN: En el año 2009, el gobierno central chino puso en marcha el plan de reforma del sistema sanitario con el objetivo de reforzar el control de las enfermedades y fomentar la salud, así como proporcionar un paquete de servicios básicos de salud pública. Los médicos rurales perciben una modesta subvención por la prestación de los servicios de salud pública relacionados con dicho paquete. Sus opiniones acerca de dicha subvención y la prestación de los servicios de salud pública podrían influir en la calidad y la eficacia de los servicios sanitarios preventivos y de la vigilancia de las enfermedades. ENFOQUE: Con objeto de comprender los puntos de vista de los médicos rurales acerca de la subvención y sus experiencias en la prestación de servicios sanitarios, hemos llevado a cabo 10 debates con grupos focales de médicos rurales, 12 entrevistas en detalle con directores de centros de salud municipales y 4 entrevistas en detalle con directores de Centros para el Control y Prevención de las Enfermedades provinciales. MARCO REGIONAL: El estudio se llevó a cabo en cuatro condados del centro de China, dos de ellos en la provincia de Hubei y otros dos en la de Jiangxi. CAMBIOS IMPORTANTES: Los médicos rurales dan prioridad a los servicios médicos, pero hacen todo lo posible por gestionar su tiempo a fin de incluir los servicios de salud pública. La disposición de los directores de los centros sanitarios municipales y de los médicos rurales para prestar los servicios de salud pública ha aumentado desde la introducción del paquete y de la subvención mínima, si bien los médicos rurales no consideran que sea una retribución suficiente por sus esfuerzos. LECCIONES APRENDIDAS: Es probable que, para mejorar la prestación de servicios de salud pública por parte de los médicos rurales, sea necesario un aumento de la subvención, una mejora en la relación de supervisión entre las clínicas rurales y los centros de salud municipales, así como la creación de una pensión gubernamental para los médicos rurales.

T Lymphocyte responses to nonpolymorphic HLA-derived peptides are associated with chronic renal allograft dysfunction.

BACKGROUND: The routine assessment of cellular alloimmunity to guide therapy is of perennial interest because this limb of the immune system is the main target of current transplant immunosuppression. That this has not as yet been realized in clinical practice reflects the difficulty of developing a standardized assay that accounts for the high degree of polymorphism exhibited by histocompatibility antigens. METHODS: We have investigated whether immune responses to peptides derived from nonpolymorphic regions of human leukocyte antigen arise after transplantation, in particular in those with chronic allograft dysfunction. RESULTS: Peripheral blood mononuclear cell γ-interferon production to peptides derived from the nonpolymorphic α3 domain of class 1 human leukocyte antigen occurred more frequently in long-term renal transplant recipients than healthy controls (51/110 vs. 1/18, 46.3% vs. 5.5%; P<0.001). These responses were associated with chronic allograft dysfunction manifested by a reduced and decreasing estimated glomerular filtration rate (responders vs. nonresponders: 39.5 vs. 48.8 mL/min, P=0.015 and -4.1 vs. -1.3 mL/min/year, P=0.008). Responses occurred mostly to autologous, "cryptic self-epitopes" and arose from CD4CD25CD127 T lymphocytes, which have been previously implicated in chronic rejection. CONCLUSION: These findings suggest a strategy for assessing cellular immune responses to transplantation antigens with potential for generalization.

Chronic graft versus host disease is associated with an immune response to autologous human leukocyte antigen-derived peptides.

BACKGROUND: Chronic graft-versus-host disease (cGVHD) is a major complication of allogeneic bone marrow transplantation (BMT) the immunopathogenesis of which is not well understood. Humoral and cellular immunity are both implicated, patients express a range of autoantibodies, but the targets of cellular immunity are not well defined. Autologous human leukocyte antigen (HLA)-derived peptides constitute a significant proportion of the repertoire. METHODS: We have investigated the response to HLA-derived peptides after allogeneic BMT using gamma-interferon enzyme-linked immunospot assay (ELISPOT). We also studied the release of this gamma-interferon by flow cytometry in a subgroup of responsive patients. RESULTS: The peripheral blood mononuclear cell response was assessed by gamma-interferon ELISPOT in 42 BMT recipients (21 with cGVHD) and 30 healthy donors. Thirteen of 21 patients diagnosed with cGVHD responded to at least one HLA-derived peptide compared with 1 of 21 patients without cGVHD (62% vs. 5%, P<10) and 1 of 30 healthy donors. In all but one patient these peptides correspond with the sequences of autologous HLA. The median single peptide-specific response in ELISPOT was 43/10 peripheral blood mononuclear cells. In a subgroup studied by flow cytometry, gamma-interferon production to individual peptides occurred in 0.04% to 0.18% of CD4 T lymphocytes. CONCLUSION: These observations identify HLA-derived peptides as targets of a cellular immune response in cGVHD.

Language and rigour in qualitative research: problems and principles in analyzing data collected in Mandarin.

In collaborative qualitative research in Asia, data are usually collected in the national language, and this poses challenges for analysis. Translation of transcripts to a language common to the whole research team is time consuming and expensive; meaning can easily be lost in translation; and validity of the data may be compromised in this process. We draw on several published examples from public health research conducted in mainland China, to highlight how language can influence rigour in the qualitative research process; for each problem we suggest potential solutions based on the methods used in one of our research projects in China. Problems we have encountered include obtaining sufficient depth and detail in qualitative data; deciding on language for data collection; managing data collected in Mandarin; and the influence of language on interpreting meaning. We have suggested methods for overcoming problems associated with collecting, analysing, and interpreting qualitative data in a local language, that we think help maintain analytical openness in collaborative qualitative research. We developed these methods specifically in research conducted in Mandarin in mainland China; but they need further testing in other countries with data collected in other languages. Examples from other researchers are needed.

Patient adherence to tuberculosis treatment: a systematic review of qualitative research.

BACKGROUND: Tuberculosis (TB) is a major contributor to the global burden of disease and has received considerable attention in recent years, particularly in low- and middle-income countries where it is closely associated with HIV/AIDS. Poor adherence to treatment is common despite various interventions aimed at improving treatment completion. Lack of a comprehensive and holistic understanding of barriers to and facilitators of, treatment adherence is currently a major obstacle to finding effective solutions. The aim of this systematic review of qualitative studies was to understand the factors considered important by patients, caregivers and health care providers in contributing to TB medication adherence. METHODS AND FINDINGS: We searched 19 electronic databases (1966-February 2005) for qualitative studies on patients', caregivers', or health care providers' perceptions of adherence to preventive or curative TB treatment with the free text terms "Tuberculosis AND (adherence OR compliance OR concordance)". We supplemented our search with citation searches and by consulting experts. For included studies, study quality was assessed using a predetermined checklist and data were extracted independently onto a standard form. We then followed Noblit and Hare's method of meta-ethnography to synthesize the findings, using both reciprocal translation and line-of-argument synthesis. We screened 7,814 citations and selected 44 articles that met the prespecified inclusion criteria. The synthesis offers an overview of qualitative evidence derived from these multiple international studies. We identified eight major themes across the studies: organisation of treatment and care; interpretations of illness and wellness; the financial burden of treatment; knowledge, attitudes, and beliefs about treatment; law and immigration; personal characteristics and adherence behaviour; side effects; and family, community, and household support. Our interpretation of the themes across all studies produced a line-of-argument synthesis describing how four major factors interact to affect adherence to TB treatment: structural factors, including poverty and gender discrimination; the social context; health service factors; and personal factors. The findings of this study are limited by the quality and foci of the included studies. CONCLUSIONS: Adherence to the long course of TB treatment is a complex, dynamic phenomenon with a wide range of factors impacting on treatment-taking behaviour. Patients' adherence to their medication regimens was influenced by the interaction of a number of these factors. The findings of our review could help inform the development of patient-centred interventions and of interventions to address structural barriers to treatment adherence.

Downregulation of ubiquitin-dependent protein degradation in murine myotubes during hyperthermia by eicosapentaenoic acid.

Muscle atrophy in a number of acute wasting conditions is associated with an increased activity and expression of the ubiquitin-proteasome proteolytic pathway. Although different initiators are involved, it is possible that the intracellular signalling events leading to upregulation of this pathway are the same in all catabolic conditions. This study investigates hyperthermia in murine myotubes as a model for increased protein degradation through the ubiquitin-proteasome pathway. The effect of eicosapentaenoic acid (EPA) on this process should identify common elements, since EPA has been shown to attenuate induction of the ubiquitin-proteasome pathway in cancer cachexia. Increasing the temperature of myotubes caused a progressive increase in protein degradation. This was associated with an increased proteasome 'chymotrypsin-like' enzyme activity, as well as increased expression of both mRNA and protein for 20S proteasome subunits and the ubiquitin-conjugating enzyme (E2(14k)). This upregulation was not seen in cultures treated with EPA (50 microM), suggesting that it acts to prevent transcriptional activation of the ubiquitin-proteasome pathway in hyperthermia. These results suggest that protein catabolism in hyperthermia and cancer cachexia is mediated through a common pathway.

Attenuation of proteasome-induced proteolysis in skeletal muscle by {beta}-hydroxy-{beta}-methylbutyrate in cancer-induced muscle loss.

Loss of skeletal muscle is an important determinant of survival in patients with cancer-induced weight loss. The effect of the leucine metabolite beta-hydroxy-beta-methylbutyrate (HMB) on the reduction of body weight loss and protein degradation in the MAC16 model of cancer-induced weight loss has been compared with that of eicosapentaenoic acid (EPA), a recognized inhibitor of protein degradation. HMB was found to attenuate the development of weight loss at a dose greater than 0.125 g/kg accompanied by a small reduction in tumor growth rate. When EPA was used at a suboptimal dose level (0.6 g/kg) the combination with HMB seemed to enhance the anticachectic effect. Both treatments caused an increase in the wet weight of soleus muscle and a reduction in protein degradation, although there did not seem to be a synergistic effect of the combination. Proteasome activity, determined by the "chymotrypsin-like" enzyme activity, was attenuated by both HMB and EPA. Protein expression of the 20S alpha or beta subunits was reduced by at least 50%, as were the ATPase subunits MSS1 and p42 of the 19S proteasome regulatory subunit. This was accompanied by a reduction in the expression of E2(14k) ubiquitin-conjugating enzyme. The combination of EPA and HMB was at least as effective or more effective than either treatment alone. Attenuation of proteasome expression was reflected as a reduction in protein degradation in gastrocnemius muscle of cachectic mice treated with HMB. In addition, HMB produced a significant stimulation of protein synthesis in skeletal muscle. These results suggest that HMB preserves lean body mass and attenuates protein degradation through down-regulation of the increased expression of key regulatory components of the ubiquitin-proteasome proteolytic pathway, together with stimulation of protein synthesis.

Mechanism of the attenuation of proteolysis-inducing factor stimulated protein degradation in muscle by beta-hydroxy-beta-methylbutyrate.

The leucine metabolite beta-hydroxy-beta-methylbutyrate (HMB) prevents muscle protein degradation in cancer-induced weight loss through attenuation of the ubiquitin-proteasome proteolytic pathway. To investigate the mechanism of this effect, the action of HMB on protein breakdown and intracellular signaling leading to increased proteasome expression by the tumor factor proteolysis-inducing factor (PIF) has been studied in vitro using murine myotubes as a surrogate model of skeletal muscle. A comparison has been made of the effects of HMB and those of eicosapentaenoic acid (EPA), a known inhibitor of PIF signaling. At a concentration of 50 mumol/L, EPA and HMB completely attenuated PIF-induced protein degradation and induction of the ubiquitin-proteasome proteolytic pathway, as determined by the "chymotrypsin-like" enzyme activity, as well as protein expression of 20S proteasome alpha- and beta-subunits and subunit p42 of the 19S regulator. The primary event in PIF-induced protein degradation is thought to be release of arachidonic acid from membrane phospholipids, and this process was attenuated by EPA, but not HMB, suggesting that HMB might act at another step in the PIF signaling pathway. EPA and HMB at a concentration of 50 mumol/L attenuated PIF-induced activation of protein kinase C and the subsequent degradation of inhibitor kappaBalpha and nuclear accumulation of nuclear factor kappaB. EPA and HMB also attenuated phosphorylation of p42/44 mitogen-activated protein kinase by PIF, thought to be important in PIF-induced proteasome expression. These results suggest that HMB attenuates PIF-induced activation and increased gene expression of the ubiquitin-proteasome proteolytic pathway, reducing protein degradation.