Delta 1-activated notch inhibits muscle differentiation without affecting Myf5 and Pax3 expression in chick limb myogenesis

The myogenic basic helix-loop-helix (bHLH) transcription factors, Myf5, MyoD, myogenin and MRF4, are unique in their ability to direct a program of specific gene transcription leading to skeletal muscle phenotype. The observation that Myf5 and MyoD can force myogenic conversion in non-muscle cells in vitro does not imply that they are equivalent. In this paper, we show that Myf5 transcripts are detected before those of MyoD during chick limb development. The Myf5 expression domain resembles that of Pax3 and is larger than that of MyoD. Moreover, Myf5 and Pax3 expression is correlated with myoblast proliferation, while MyoD is detected in post-mitotic myoblasts. These data indicate that Myf5 and MyoD are involved in different steps during chick limb bud myogenesis, Myf5 acting upstream of MyoD. The progression of myoblasts through the differentiation steps must be carefully controlled to ensure myogenesis at the right place and time during wing development. Because Notch signalling is known to prevent differentiation in different systems and species, we sought to determine whether these molecules regulate the steps occurring during chick limb myogenesis. Notch1 transcripts are associated with immature myoblasts, while cells expressing the ligands Delta1 and Serrate2 are more advanced in myogenesis. Misexpression of Delta1 using a replication-competent retrovirus activates the Notch pathway. After activation of this pathway, myoblasts still express Myf5 and Pax3 but have downregulated MyoD, resulting in inhibition of terminal muscle differentiation. We conclude that activation of Notch signalling during chick limb myogenesis prevents Myf5-expressing myoblasts from progressing to the MyoD-expressing stage.

The role of bone morphogenetic proteins in vertebral development

This study first shows a striking parallel between the expression patterns of the Bmp4, Msx1 and Msx2 genes in the lateral ridges of the neural plate before neural tube closure and later on, in the dorsal neural tube and superficial midline ectoderm. We have previously shown that the spinous process of the vertebra is formed from Msx1- and 2-expressing mesenchyme and that the dorsal neural tube can induce the differentiation of subcutaneous cartilage from the somitic mesenchyme. We show here that mouse BMP4- or human BMP2-producing cells grafted dorsally to the neural tube at E2 or E3 increase considerably the amount of Msx-expressing mesenchymal cells which are normally recruited from the somite to form the spinous process of the vertebra. Later on, the dorsal part of the vertebra is enlarged, resulting in vertebral fusion and, in some cases (e.g. grafts made at E3), in the formation of a ‘giant’ spinous process-like structure dorsally. In strong contrast, BMP-producing cells grafted laterally to the neural tube at E2 exerted a negative effect on the expression of Pax1 and Pax3 genes in the somitic mesenchyme, which then turned on Msx genes. Moreover, sclerotomal cell growth and differentiation into cartilage were then inhibited. Dorsalization of the neural tube, manifested by expression of Msx and Pax3 genes in the basal plate contacting the BMP-producing cells, was also observed. In conclusion, this study demonstrates that differentiation of the ventrolateral and dorsal parts of the vertebral cartilage is controlled by different molecular mechanisms. The former develops under the influence of signals arising from the floor plate-notochord complex. These signals inhibit the development of dorsal subcutaneous cartilage forming the spinous process, which requires the influence of BMP4 to differentiate.

Notch signalling acts in postmitotic avian myogenic cells to control MyoD activation

During Drosophila myogenesis, Notch signalling acts at multiple steps of the muscle differentiation process. In vertebrates, Notch activation has been shown to block MyoD activation and muscle differentiation in vitro, suggesting that this pathway may act to maintain the cells in an undifferentiated proliferative state. In this paper, we address the role of Notch signalling in vivo during chick myogenesis. We first demonstrate that the Notch1 receptor is expressed in postmitotic cells of the myotome and that the Notch ligands Delta1 and Serrate2 are detected in subsets of differentiating myogenic cells and are thus in position to signal to Notch1 during myogenic differentiation. We also reinvestigate the expression of MyoD and Myf5 during avian myogenesis, and observe that Myf5 is expressed earlier than MyoD, consistent with previous results in the mouse. We then show that forced expression of the Notch ligand, Delta1, during early myogenesis, using a retroviral system, has no effect on the expression of the early myogenic markers Pax3 and Myf5, but causes strong down-regulation of MyoD in infected somites. Although Delta1 overexpression results in the complete lack of differentiated muscles, detailed examination of the infected embryos shows that initial formation of a myotome is not prevented, indicating that exit from the cell cycle has not been blocked. These results suggest that Notch signalling acts in postmitotic myogenic cells to control a critical step of muscle differentiation.

Usefulness of B-Type Natriuretic Peptide Assay in the Assessment of Symptomatic State in Hypertrophic Cardiomyopathy

Background— Hypertrophic cardiomyopathy (HCM) has a diverse clinical spectrum that often includes progressive heart failure symptoms and disability. Assessment of symptom severity may be highly subjective, encumbered by the heterogeneous clinical presentation. Plasma B-type natriuretic peptide (BNP) has been used widely as an objective marker for heart failure severity and outcome, predominantly in coronary heart disease with ventricular dilatation and systolic dysfunction.

Methods and Results— We prospectively assessed plasma BNP as a quantitative clinical marker of heart failure severity in 107 consecutive HCM patients. BNP showed a statistically significant relationship to magnitude of functional limitation, assessed by New York Heart Association (NYHA) functional class: I, 136±159 pg/mL; II, 338±439 pg/mL; and III/IV, 481±334 pg/mL ( P <0.001). Multivariable analysis showed that BNP was independently related to NYHA class as well as age and left ventricular wall thickness (each with a value of P =0.0001). BNP ≥200 pg/mL was the most reliable predictor of heart failure symptoms, with positive and negative predictive values of 63% and 79%, respectively. BNP power in distinguishing patients with or without heart failure symptoms was less than that for differentiating between no (or only mild) and severe symptoms (area under receiver operating characteristic curve=0.75 and 0.83, respectively).

Conclusions— Plasma BNP is independently related to the presence and magnitude of heart failure symptoms in patients with HCM. As a clinical marker for heart failure, BNP is limited by considerable overlap in values between categories of heart failure severity as well as confounding variables of left ventricular wall thickness and age.

Aldosterone and vascular damage

Although the aldosterone escape mechanism is well known, aldosterone has often been neglected in the pathophysiologic consequences of the activated renin-angiotensin-aldosterone system in arterial hypertension and chronic heart failure. There is now evidence for vascular synthesis of aldosterone aside from its secretion by the adrenal cortex. Moreover, aldosterone is involved in vascular smooth muscle cell hypertrophy and hyperplasia, as well as in vascular matrix impairment and endothelial dysfunction. The mechanisms of action of aldosterone may be either delayed (genomic) or rapid (nongenomic). Deleterious effects of aldosterone leading to vascular target-organ damage include (besides salt and water retention) decreased arterial and venous compliance, increased peripheral vascular resistance, and impaired autonomic vascular control due to baroreflex dysfunction.

Major cardiac events for adult survivors of childhood cancer diagnosed between 1970 and 1999: report from the Childhood Cancer Survivor Study cohort

OBJECTIVE

To investigate the impact of modifications to contemporary cancer protocols, which minimize exposures to cardiotoxic treatments and preserve long term health, on serious cardiac outcomes among adult survivors of childhood cancer.

DESIGN

Retrospective cohort study.

SETTING

27 institutions participating in the Childhood Cancer Survivor Study.

PARTICIPANTS

23 462 five year survivors (6193 (26.4%) treated in the 1970s, 9363 (39.9%) treated in the 1980s, and 7906 (33.6%) treated in the 1990s) of leukemia, brain cancer, Hodgkin lymphoma, non-Hodgkin lymphoma, renal tumors, neuroblastoma, soft tissue sarcomas, and bone sarcomas diagnosed prior to age 21 years between 1 January 1970 and 31 December 1999. Median age at diagnosis was 6.1 years (range 0-20.9) and 27.7 years (8.2-58.3) at last follow-up. A comparison group of 5057 siblings of cancer survivors were also included.

MAIN OUTCOME MEASURES

Cumulative incidence and 95% confidence intervals of reported heart failure, coronary artery disease, valvular heart disease, pericardial disease, and arrhythmias by treatment decade. Events were graded according to the National Cancer Institute's Common Terminology Criteria for Adverse Events. Multivariable subdistribution hazard models were used to estimate hazard ratios by decade, and mediation analysis examined risks with and without exposure to cardiotoxic treatments.

RESULTS

The 20 year cumulative incidence of heart failure (0.69% for those treated in the 1970s, 0.74% for those treated in the 1980s, 0.54% for those treated in the 1990s) and coronary artery disease (0.38%, 0.24%, 0.19%, respectively), decreased in more recent eras (P<0.01), though not for valvular disease (0.06%, 0.06%, 0.05%), pericardial disease (0.04%, 0.02%, 0.03%), or arrhythmias (0.08%, 0.09%, 0.13%). Compared with survivors with a diagnosis in the 1970s, the risk of heart failure, coronary artery disease, and valvular heart disease decreased in the 1980s and 1990s but only significantly for coronary artery disease (hazard ratio 0.65, 95% confidence interval 0.45 to 0.92 and 0.53, 0.36 to 0.77, respectively). The overall risk of coronary artery disease was attenuated by adjustment for cardiac radiation (0.90, 0.78 to 1.05), particularly among survivors of Hodgkin lymphoma (unadjusted for radiation: 0.77, 0.66 to 0.89; adjusted for radiation: 0.87, 0.69 to 1.10).

CONCLUSIONS

Historical reductions in exposure to cardiac radiation have been associated with a reduced risk of coronary artery disease among adult survivors of childhood cancer. Additional follow-up is needed to investigate risk reductions for other cardiac outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01120353.

Determination of arterial compliance using blood pressure waveform analysis with the CR-2000 system: Reliability, repeatability, and establishment of normal values for healthy European population--the seven European sites study (SESS)

BACKGROUND

We determined the reliability and repeatability of measurements of arterial compliance (AC) and gender- and age-specific normal ranges for a healthy European population.

METHODS

Three hundred eight healthy volunteers from seven sites were evaluated. Two measurements were taken during the first visit, repeated on a second visit 1 to 4 weeks later. We used the HDI/PulseWave CR-2000 for measurements of AC.

RESULTS

Intravisit measurements, taken 5 min apart, differed by less than 3% (range, 0.36% to 2.97%). All intervisit measures differed by less than 4% (range, 0.24% to 3.67%); none of these differences was statistically significant. All correlation coefficients for pairs of AC parameters measured 5 min apart at the same visit were significant at P < .0001. Paired AC parameters at visit 1 and 2 were highly correlated (P < .0001). Repeated measures GLM (general linear model) failed to detect a significant association between either of the AC parameters and visit (first or second), time (first or second measure at the same visit), and visit-by-time (the interaction of the two preceding factors), suggesting that order of measure had no effect on the final value. Analysis of reliability was used to develop a strictly parallel model estimate of unbiased reliability. Both intravisit and intervisit estimates of reliability indicate good repeatability of measure and were significant (P < .0001). The AC values were found to differ significantly by age group, with an inverse association between each of the AC parameters and age group.

CONCLUSIONS

Measurement of the arterial waveform with the CR-2000 system is highly reproducible in healthy subjects.

High-density lipoprotein particles and markers of inflammation and thrombotic activity in patients with untreated HIV infection

BACKGROUND

Untreated human immunodeficiency virus (HIV) infection is associated with changes in blood lipids, inflammation, thrombotic activity, and increased risk for cardiovascular disease.

METHODS

We studied high-density lipoprotein particle (HDLp) concentrations and inflammatory (high-sensitivity C-reactive protein [hsCRP] and interleukin [IL] 6), endothelial activation (E-selectin and soluble intercellular adhesion molecule-1 [sICAM-1]), and thrombotic (fibrinogen and D-dimer) biomarkers in a group of 32 untreated HIV-infected and 29 uninfected persons. Differences in the levels of blood lipids and biomarkers by HIV status were examined before and after adjustment for age, sex, race/ethnicity, smoking status, body mass index, and the presence of hepatitis C.

RESULTS

HIV-infected participants, compared with uninfected participants, had lower HDL cholesterol (HDLc) levels (-26%) and HDLp numbers (-21%), with reductions in large (-50%) and small (-20%) HDLp, specifically (P < or = .01 for all). A trend was present for higher total cholesterol (P = .15 and triglyceride levels (P = .11) among individuals with HIV infection. Levels of IL-6, sICAM-1, and D-dimer were 65%-70% higher in HIV-infected participants (P < or = .02 for all). Covariate adjustment did not diminish these associations. For HIV-infected participants, total and small HDLp (respectively) tended to correlate inversely with levels of IL-6 (P = .08 and P = .02), sICAM-1 (P < .01 for both) and D-dimer (P = .03 and p < .01).

CONCLUSIONS

Persons with untreated HIV infection have lower HDLp (primarily large and small HDLp) and higher IL-6, sICAM-1, and D-dimer levels, and the relationship of these markers to HIV-mediated atherosclerotic risk requires further study.

Association of sleep characteristics with atrial fibrillation: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Population-based studies have linked measures of sleep disordered breathing to nocturnally occurring atrial fibrillation (AF) episodes. Whether measures of sleep disordered breathing and sleep quality are associated with prevalent AF has not been studied in an unselected population. We investigated the cross-sectional association with prevalent AF of objectively collected prespecified measures of overnight sleep breathing disturbances, sleep stage distributions, arousal and sleep duration.

METHODS

AF prevalence, defined by diagnosis codes, study electrocardiography and sleep study were examined among Multi-Ethnic Study of Atherosclerosis (MESA) participants who underwent polysomnography in the MESA Sleep Study (n=2048).

MEASUREMENTS AND MAIN RESULTS

Higher apnoea hypopnoea index (AHI) was associated with increased odds of AF, although the significance was attenuated after full adjustment for covariates including prevalent cardiovascular disease (OR: 1.22 (0.99 to 1.49) per SD (17/h), p=0.06). Analyses of sleep architecture measures and AF revealed significantly lower odds of AF associated with longer duration of slow wave sleep (OR: 0.66 (0.5 to 0.89) per SD (34 min), p=0.01) which persisted after additionally adjusting for AHI (OR: 0.68 (0.51 to 0.92), p=0.01). Higher sleep efficiency was significantly associated with lower likelihood of AF but the significance was lost when adjusted for AHI. No significant association was present between sleep duration and AF. In a model including AHI and arousal index, the association between AHI and AF was strengthened (AHI: OR 1.49 (1.15 to 1.91) per SD, p=0.002) and a significant inverse association between arousal index and AF was observed (OR 0.65 (0.50 to 0.86) per SD (12/h), p=0.005).

CONCLUSIONS

In a study of a large multiethnic population, AF was associated with AHI severity, and was more common in individuals with poor sleep quality as measured by reduced slow wave sleep time, a finding that was independent of AHI.

Structural and functional vascular alterations and incident hypertension in normotensive adults: the Multi-Ethnic Study of Atherosclerosis

Vascular abnormalities may exist before clinical hypertension. Using Poisson regression, the authors studied the association of coronary artery calcium (CAC), common carotid intima-media thickness (CIMT), aortic distensibility, and large and small arterial elasticity with incident hypertension among 2,512 normotensive US adults free of cardiovascular disease. Incidence rate ratios for incident hypertension (blood pressure > or =140/90 mm Hg or new antihypertensive medication) were calculated. Increased CAC was associated with incident hypertension in demographics-adjusted models (incidence rate ratio (IRR) = 1.35, 95% confidence interval (CI): 1.04, 1.75; IRR = 1.35, 95% CI: 1.02, 1.78; and IRR = 1.59, 95% CI: 1.12, 2.25 for CAC scores of 30-99, 100-399, and > or =400, respectively) but was attenuated after further adjustment. Increased common CIMT was associated with incident hypertension (IRR = 1.77, 95% CI: 1.28, 2.46 for quintile 4; IRR = 1.80, 95% CI: 1.28, 2.53 for quintile 5). Participants with the lowest, compared with the highest, aortic distensibility had an increased risk of hypertension (IRR = 1.75, 95% CI: 1.10, 2.79), as did those with the lowest large arterial elasticity (IRR = 1.49, 95% CI: 1.11, 1.99). Lower small arterial elasticity was incrementally associated with incident hypertension starting at quintile 2 (IRR = 2.01, 95% CI: 1.39, 2.91; IRR = 2.47, 95% CI: 1.71, 3.57; IRR = 2.73, 95% CI: 1.88, 3.95; and IRR = 2.85, 95% CI: 1.95, 4.16). Structural and functional vascular abnormalities are independent predictors of incident hypertension. These findings are important for understanding the pathogenesis of hypertension.

Diet quality indexes and mortality in postmenopausal women: the Iowa Women's Health Study

BACKGROUND

A priori diet scores such as the Alternative Healthy Eating Index (AHEI) and the food-based a priori diet quality score predict chronic disease risk.

OBJECTIVE

We compared the AHEI and a priori diet quality score relative to mortality.

DESIGN

Postmenopausal women who were free of diabetes, cardiovascular disease (CVD), and cancer in the Iowa Women's Health Study (in 1986, n = 29,634 with a mean 6 SD age of 61.4 6 4.2 y; in 2004, n = 15,076 with a mean 6 SD age of 79.7 6 4.0 y). A food-frequency questionnaire was used. Through 31 December 2008, 10,343 total, 3646 CVD, 3207 cancer, and 2888 inflammatory-related deaths were identified through record linkage. HRs were computed for quartiles of each diet score at baseline and 2004. To compare scores, the residual of each score given the other score was computed by using linear regression.

RESULTS

At baseline, indexes had a correlation of 0.65. For the AHEI, the multivariable-adjusted HRs (95% CIs) for total, CVD, cancer, and inflammatory-related mortality were 0.82 (0.77, 0.87), 0.79 (0.72, 0.88), 0.88 (0.79, 0.98), and 0.76 (0.68, 0.84), respectively. The a priori score had corresponding HRs of 0.80 (0.76, 0.85), 0.79 (0.72, 0.88), 0.86 (0.77, 0.95), and 0.75 (0.67, 0.84), respectively. Each score added information to the other score for total, CVD mortality, and inflammatory-related mortality. In 2004, both scores predicted total, CVD, and inflammatory-related mortality, and the a priori score also predicted cancer mortality. The a priori score added independent information for all outcomes except cancer, whereas the AHEI added information only for total mortality.

CONCLUSION

Two correlated diet quality scores predicted total and disease-specific mortality, but their residuals also predicted complementarily.

Interruption of antiretroviral therapy and risk of cardiovascular disease in persons with HIV-1 infection: exploratory analyses from the SMART trial

BACKGROUND

The SMART trial found a raised risk of cardiovascular disease (CVD) events in patients undergoing CD4+ T cell-count guided intermittent antiretroviral therapy (ART) compared with patients on continuous ART. Exploratory analyses were performed to better understand the reasons for this observation.

METHODS

A total of 5,472 patients with CD4+ T-cell counts >350 cells/mm3 were recruited and randomized to either continuous ART (the viral suppression arm; VS) or CD4+ T-cell count-guided use of ART (the drug conservation arm; DC).

RESULTS

Major CVD events developed in 79 patients. The hazard ratio (HR) for risk of CVD events for DC versus VS was 1.57 (95% confidence interval 1.00-2.46; P=0.05). There was no evidence that being off ART or a higher current HIV viral load were associated with increased CVD risk. Total cholesterol and low-density lipoprotein cholesterol were reduced as a result of ART interruption in DC patients but so was high-density lipoprotein (HDL) cholesterol, leading to a net unfavourable change in the total/HDL cholesterol ratio.

CONCLUSIONS

Reasons for the higher risk of CVD for DC compared with VS patients remain unclear. There was no clear evidence to suggest that ART interruption per se or a higher HIV viral load were associated with an increased CVD risk in the DC group. Lipid changes were less favourable among DC compared with VS patients, which could offer a partial explanation.

Composition-dependent morphostructural properties of Ni-Cu oxide nanoparticles confined within the channels of ordered mesoporous SBA-15 silica

NiO and NiO-CuO polycrystalline rodlike nanoparticles were confined and stabilized within the channels of ordered mesoporous SBA-15 silica by a simple and viable approach consisting in incipient wetness impregnation of the calcined support with aqueous solutions of metal nitrates followed by a mild drying step at 25 °C and calcination. As revealed by low- and high-angle XRD, N2 adsorption/desorption, HRTEM/EDXS and H2 TPR analyses, the morphostructural properties of NiO-CuO nanoparticles can be controlled by adjusting their chemical composition, creating the prerequisites to obtain high performance bimetallic catalysts. Experimental evidence by in situ XRD monitoring during the thermoprogrammed reduction indicates that the confined NiO-CuO nanoparticles evolve into thermostable and well-dispersed Ni-Cu heterostructures. The strong Cu-Ni and Ni-support interactions demonstrated by TPR and XPS were put forward to explain the formation of these new bimetallic structures. The optimal Ni-Cu/SBA-15 catalyst (i.e., Cu/(Cu+Ni) atomic ratio of 0.2) proved a greatly enhanced reducibility and H2 chemisorption capacity, and an improved activity in the hydrogenation of cinnamaldehyde, as compared with the monometallic Ni/SBA-15 or Cu/SBA-15 counterparts, which can be associated with the synergism between nickel and copper and high dispersion of active components on the SBA-15 host. The unique structure and controllable properties of both oxidic and metallic forms of Ni-Cu/SBA-15 materials make them very attractive for both fundamental research and practical catalytic applications.

A Study of 15N/14N Isotopic Exchange over Cobalt Molybdenum Nitrides

The 14N/15N isotopic exchange pathways over Co3Mo3N, a material of interest as an ammonia synthesis catalyst and for the development of nitrogen transfer reactions, have been investigated. Both the homomolecular and heterolytic exchange processes have been studied, and it has been shown that lattice nitrogen species are exchangeable. The exchange behavior was found to be a strong function of pretreatment with ca. 25% of lattice N atoms being exchanged after 40 min at 600 °C after N2 pretreatment at 700 °C compared to only 6% following similar Ar pretreatment. This observation, for which the potential contribution of adsorbed N species can be discounted, is significant in terms of the application of this material. In the case of the Co6Mo6N phase, regeneration to Co3Mo3N under 15N2 at 600 °C occurs concurrently with 14N15N formation. These observations demonstrate the reactivity of nitrogen in the Co-Mo-N system to be a strong function of pretreatment and worthy of further consideration.