Hypoxia-induced cardiac injury in dystrophic mice.

Duchenne muscular dystrophy (DMD) is a disease of progressive destruction of striated muscle, resulting in muscle weakness with progressive respiratory and cardiac failure. Respiratory and cardiac disease are the leading causes of death in DMD patients. Previous studies have suggested an important link between cardiac dysfunction and hypoxia in the dystrophic heart; these studies aim to understand the mechanism underlying this connection. Here we demonstrate that anesthetized dystrophic mice display significant mortality following acute exposure to hypoxia. This increased mortality is associated with a significant metabolic acidosis, despite having significantly higher levels of arterial Po2 Chronic hypoxia does not result in mortality, but rather is characterized by marked cardiac fibrosis. Studies in isolated hearts reveal that the contractile function of dystrophic hearts is highly susceptible to short bouts of ischemia, but these hearts tolerate prolonged acidosis better than wild-type hearts, indicating an increased sensitivity of the dystrophic heart to hypoxia. Dystrophic hearts display decreased cardiac efficiency and oxygen extraction. Isolated dystrophic cardiomyocytes and hearts have normal levels of FCCP-induced oxygen consumption, and mitochondrial morphology and content are normal in the dystrophic heart. These studies demonstrate reductions in cardiac efficiency and oxygen extraction of the dystrophic heart. The underlying cause of this reduced oxygen extraction is not clear; however, the current studies suggest that large disruptions of mitochondrial respiratory function or coronary flow regulation are not responsible. This finding is significant, as hypoxia is a common and largely preventable component of DMD that may contribute to the progression of the cardiac disease in DMD patients.

Dystrobrevin increases dystrophin's binding to the dystrophin-glycoprotein complex and provides protection during cardiac stress.

Duchenne muscular dystrophy is a fatal progressive disease of both cardiac and skeletal muscle resulting from the mutations in the DMD gene and loss of the protein dystrophin. Alpha-dystrobrevin (α-DB) tightly associates with dystrophin but the significance of this interaction within cardiac myocytes is poorly understood. In the current study, the functional role of α-DB in cardiomyocytes and its implications for dystrophin function are examined. Cardiac stress testing demonstrated significant heart disease in α-DB null (adbn(-/-)) mice, which displayed mortality and lesion sizes that were equivalent to those seen in dystrophin-deficient mdx mice. Despite normal expression and subcellular localization of dystrophin in the adbn(-/-) heart, there is a significant decrease in the strength of dystrophin's interaction with the membrane-bound dystrophin-associated glycoprotein complex (DGC). A similar weakening of the dystrophin-membrane interface was observed in mice lacking the sarcoglycan complex. Cardiomyocytes from adbn(-/-) mice were smaller and responded less to adrenergic receptor induced hypertrophy. The basal decrease in size could not be attributed to aberrant Akt activation. In addition, the organization of the microtubule network was significantly altered in adbn(-/-) cardiac myocytes, while the total expression of tubulin was unchanged in adbn(-/-) hearts. These studies demonstrate that α-DB is a multifunctional protein that increases dystrophin's binding to the dystrophin-glycoprotein complex, and is critical for the full functionality of dystrophin.

Alterations of dystrophin-associated glycoproteins in the heart lacking dystrophin or dystrophin and utrophin.

Heart disease is a leading cause of death in patients with Duchenne muscular dystrophy (DMD). Patients with DMD lack the protein dystrophin, which is widely expressed in striated muscle. In skeletal muscle, the loss of dystrophin results in dramatically decreased expression of the dystrophin associated glycoprotein complex (DGC). Interestingly, in the heart the DGC is normally expressed without dystrophin; this has been attributed to presence of the dystrophin homologue utrophin. We demonstrate here that neither utrophin nor dystrophin are required for the expression of the cardiac DGC. However, alpha-dystroglycan (α-DG), a major component of the DGC, is differentially glycosylated in dystrophin-(mdx) and dystrophin-/utrophin-(dko) deficient mouse hearts. In both models the altered α-DG retains laminin binding activity, but has an altered localization at the sarcolemma. In hearts lacking both dystrophin and utrophin, the alterations in α-DG glycosylation are even more dramatic with changes in gel migration equivalent to 24 ± 3 kDa. These data show that the absence of dystrophin and utrophin alters the processing of α-DG; however it is not clear if these alterations are a consequence of the loss of a direct interaction with dystrophin/utrophin or results from an indirect response to the presence of severe pathology. Recently there have been great advances in our understanding of the glycosylation of α-DG regarding its role as a laminin receptor. Here we present data that alterations in glycosylation occur in the hearts of animal models of DMD, but these changes do not affect laminin binding. The physiological consequences of these alterations remain unknown, but may have significant implications for the development of therapies for DMD.

Inequalities in the dental health needs and access to dental services among looked after children in Scotland: a population data linkage study.

BACKGROUND: There is limited evidence on the health needs and service access among children and young people who are looked after by the state. The aim of this study was to compare dental treatment needs and access to dental services (as an exemplar of wider health and well-being concerns) among children and young people who are looked after with the general child population. METHODS: Population data linkage study utilising national datasets of social work referrals for 'looked after' placements, the Scottish census of children in local authority schools, and national health service's dental health and service datasets. RESULTS: 633 204 children in publicly funded schools in Scotland during the academic year 2011/2012, of whom 10 927 (1.7%) were known to be looked after during that or a previous year (from 2007-2008). The children in the looked after children (LAC) group were more likely to have urgent dental treatment need at 5 years of age: 23%vs10% (n=209/16533), adjusted (for age, sex and area socioeconomic deprivation) OR 2.65 (95% CI 2.30 to 3.05); were less likely to attend a dentist regularly: 51%vs63% (n=5519/388934), 0.55 (0.53 to 0.58) and more likely to have teeth extracted under general anaesthesia: 9%vs5% (n=967/30253), 1.91 (1.78 to 2.04). CONCLUSIONS: LAC are more likely to have dental treatment needs and less likely to access dental services even when accounting for sociodemographic factors. Greater efforts are required to integrate child social and healthcare for LAC and to develop preventive care pathways on entering and throughout their time in the care system.

Policy for home or hospice as the preferred place of death from cancer: Scottish Health and Ethnicity Linkage Study population cohort shows challenges across all ethnic groups in Scotland.

BACKGROUND: Place of cancer death varies ethnically and internationally. Palliative care reviews highlight limited ability to demonstrate equal access due to incomplete or unreliable ethnicity data. AIM: To establish place of cancer death by ethnicity and describe patient characteristics. DESIGN: We linked census, hospital episode and mortality data for 117 467 persons dying of cancer, 2001-2009. With White Scottish population as reference, prevalence ratios (PR), 95% CIs and p values of death in hospital, home or hospice adjusted for sex and age were calculated by ethnic group. RESULTS: White Scottish group and minority ethnic groups combined constituted 91% and 0.4% of cancer deaths, respectively. South Asian, Chinese and African Origin patients were youngest at death (66, 66 and 65.9 years). Compared with the Scottish White reference, the White Irish (1.15 (1.10 to 1.22), p<0.0001) and Other White British (1.07 (1.02 to 1.12), p=0.003) groups were more likely to die at home. Generally, affluent Scottish White patients were less likely to die in hospital and more likely to die at home or in a hospice regardless of socioeconomic indicator used. CONCLUSIONS: Cancer deaths occur most often in hospital (52.3%) for all ethnic groups. Regardless of the socioeconomic indicator used, more affluent Scottish White patients were less likely to die in hospital; existing socioeconomic indicators detected no clear trend for the non-White population. Regardless of ethnic group, significant work is required to achieve more people dying at home or the setting of their choice.

Association between socioeconomic factors and cancer risk: a population cohort study in Scotland (1991-2006).

BACKGROUND: Lung and upper aero-digestive tract (UADT) cancer risk are associated with low socioeconomic circumstances and routinely measured using area socioeconomic indices. We investigated effect of country of birth, marital status, one area deprivation measure and individual socioeconomic variables (economic activity, education, occupational social class, car ownership, household tenure) on risk associated with lung, UADT and all cancer combined (excluding non melanoma skin cancer). METHODS: We linked Scottish Longitudinal Study and Scottish Cancer Registry to follow 203,658 cohort members aged 15+ years from 1991-2006. Relative risks (RR) were calculated using Poisson regression models by sex offset for person-years of follow-up. RESULTS: 21,832 first primary tumours (including 3,505 lung, 1,206 UADT) were diagnosed. Regardless of cancer, economically inactivity (versus activity) was associated with increased risk (male: RR 1.14, 95% CI 1.10-1.18; female: RR 1.06, 95% CI 1.02-1.11). For lung cancer, area deprivation remained significant after full adjustment suggesting the area deprivation cannot be fully explained by individual variables. No or non degree qualification (versus degree) was associated with increased lung risk; likewise for UADT risk (females only). Occupational social class associations were most pronounced and elevated for UADT risk. No car access (versus ownership) was associated with increased risk (excluding all cancer risk, males). Renting (versus home ownership) was associated with increased lung cancer risk, UADT cancer risk (males only) and all cancer risk (females only). Regardless of cancer group, elevated risk was associated with no education and living in deprived areas. CONCLUSIONS: Different and independent socioeconomic variables are inversely associated with different cancer risks in both sexes; no one socioeconomic variable captures all aspects of socioeconomic circumstances or life course. Association of multiple socioeconomic variables is likely to reflect the complexity and multifaceted nature of deprivation as well as the various roles of these dimensions over the life course.

Socioeconomic inequalities in incidence of lung and upper aero-digestive tract cancer by age, tumour subtype and sex: a population-based study in Scotland (2000-2007).

BACKGROUND: Lung and upper aero-digestive tract (UADT) cancer risk is associated with socioeconomic inequality (SEI) but the degree of socioeconomic burden by age, tumour subtype, and sex is not known. METHODS: We reviewed 216,305 cases excluding non melanoma skin cancer (All Cancer) comprising 37,274 lung; 8216 head and neck; and 6534 oesophageal cancers from 2000 to 2007 classified into anatomical or morphology subtypes. Deprivation was measured using the Scottish Index of Multiple Deprivation and SEI was measured using the Slope Index of Inequality and the Relative Index of Inequality (RII). Analyses were partitioned by 5-year age group and sex. RII was adapted to rank tumour type contribution to All Cancer SEI and to examine subtype by age and sex simultaneously. Rank was defined as proportion of All Cancer SEI. RESULTS: All Cancer SEI was greater for males (RII=0.366; female RII=0.279); the combination of lung and UADT SEI contributed 91% and 81% respectively to All Cancer SEI. For both sexes lung and UADT subtypes showed significant SEI (P<0.001) except oesophageal adenocarcinoma in males (P=0.193); for females, SEI was borderline significant (P=0.048). Although RII rank differed by sex, all lung and larynx subtypes contributed most to All Cancer SEI with RII rank for oral cavity, oesophagus-squamous cell, and oropharynx following. For males 40-44 years, SEI increased abruptly peaking at 55-59 years. For females, SEI gradually peaked 10 years later. In both sexes, the SEI peak preceded peak incidence. CONCLUSION: SEI in lung and UADT cancers vary greatly by age, tumour subtype and sex; these variations are likely to largely reflect differences between the sexes in risk behaviours which vary by birth cohort and are socioeconomically patterned.

Homozygosity mapping and exome sequencing reveal GATAD1 mutation in autosomal recessive dilated cardiomyopathy.

BACKGROUND: Dilated cardiomyopathy (DCM) is a heritable, genetically heterogeneous disorder that typically exhibits autosomal dominant inheritance. Genomic strategies enable discovery of novel, unsuspected molecular underpinnings of familial DCM. We performed genome-wide mapping and exome sequencing in a unique family wherein DCM segregated as an autosomal recessive (AR) trait. METHODS AND RESULTS: Echocardiography in 17 adult descendants of first cousins revealed DCM in 2 female siblings and idiopathic left ventricular enlargement in their brother. Genotyping and linkage analysis mapped an AR DCM locus to chromosome arm 7q21, which was validated and refined by high-density homozygosity mapping. Exome sequencing of the affected sisters was then used as a complementary strategy for mutation discovery. An iterative bioinformatics process was used to filter >40,000 genetic variants, revealing a single shared homozygous missense mutation localized to the 7q21 critical region. The mutation, absent in HapMap, 1000 Genomes, and 474 ethnically matched controls, altered a conserved residue of GATAD1, encoding GATA zinc finger domain-containing protein 1. Thirteen relatives were heterozygous mutation carriers with no evidence of myocardial disease, even at advanced ages. Immunohistochemistry demonstrated nuclear localization of GATAD1 in left ventricular myocytes, yet subcellular expression and nuclear morphology were aberrant in the proband. CONCLUSIONS: Linkage analysis and exome sequencing were used as synergistic genomic strategies to identify GATAD1 as a gene for AR DCM. GATAD1 binds to a histone modification site that regulates gene expression. Consistent with murine DCM caused by genetic disruption of histone deacetylases, the data implicate an inherited basis for epigenetic dysregulation in human heart failure.

Reduced risk of oestrogen receptor positive breast cancer among peri- and post-menopausal women in Scotland following a striking decrease in use of hormone replacement therapy.

Many countries report a decline in breast cancer incidence among peri- and post-menopausal women following a decline in HRT prescribing. To investigate recent Scottish incidence trends, European age-standardised incidence rates from 1997 to 2005 were stratified by method of first detection, ER status and age group. We developed change point models of the annual age-specific cases for the peri- and post-menopausal age groups and ER status using Poisson regression. In Scotland all HRT categories together show a 32.4% increase in the number of items dispensed in 1993-2000 followed by a striking 61.8% decline by 2007. The incidence rates of screen-detected tumours increased gradually in the 50-64 and 65-74 age groups. For the older age group this increase accelerated after 2003 corresponding to an extension of the age range of screening. For ER positive tumours in the 50-64 age group, age-standardised rates increased 31.5% from 1997 to 2000, followed by a statistically significant decrease of 11.2% by 2005 (change in slope=-0.0943, P<0.0001). We conclude that an overall incidence in the 50-64 age group declined since 2000 reflecting the sudden fall in HRT dispensed items and is largely accounted for by the decrease in ER positive tumour incidence. A longer term decline in ER negative tumours for this age group was pre-existing and is unaffected by the collapse in HRT prescribing.