Quasi-Normal Modes of Stars and Black Holes

Perturbations of stars and black holes have been one of the main topics of relativistic astrophysics for the last few decades. They are of particular importance today, because of their relevance to gravitational wave astronomy. In this review we present the theory of quasi-normal modes of compact objects from both the mathematical and astrophysical points of view. The discussion includes perturbations of black holes (Schwarzschild, Reissner-Nordstr\"om, Kerr and Kerr-Newman) and relativistic stars (non-rotating and slowly-rotating). The properties of the various families of quasi-normal modes are described, and numerical techniques for calculating quasi-normal modes reviewed. The successes, as well as the limits, of perturbation theory are presented, and its role in the emerging era of numerical relativity and supercomputers is discussed.Comment: 74 pages, 7 figures, Review article for "Living Reviews in Relativity

The Antibacterial Activity of Honey Derived from Australian Flora

Chronic wound infections and antibiotic resistance are driving interest in antimicrobial treatments that have generally been considered complementary, including antimicrobially active honey. Australia has unique native flora and produces honey with a wide range of different physicochemical properties. In this study we surveyed 477 honey samples, derived from native and exotic plants from various regions of Australia, for their antibacterial activity using an established screening protocol. A level of activity considered potentially therapeutically useful was found in 274 (57%) of the honey samples, with exceptional activity seen in samples derived from marri (Corymbia calophylla), jarrah (Eucalyptus marginata) and jellybush (Leptospermum polygalifolium). In most cases the antibacterial activity was attributable to hydrogen peroxide produced by the bee-derived enzyme glucose oxidase. Non-hydrogen peroxide activity was detected in 80 (16.8%) samples, and was most consistently seen in honey produced from Leptospermum spp. Testing over time found the hydrogen peroxide-dependent activity in honey decreased, in some cases by 100%, and this activity was more stable at 4°C than at 25°C. In contrast, the non-hydrogen peroxide activity of Leptospermum honey samples increased, and this was greatest in samples stored at 25°C. The stability of non-peroxide activity from other honeys was more variable, suggesting this activity may have a different cause. We conclude that many Australian honeys have clinical potential, and that further studies into the composition and stability of their active constituents are warranted

Fibrillary glomerulonephritis with small fibrils in a patient with the antiphospholipid antibody syndrome successfully treated with immunosuppressive therapy

10.1186/1471-2369-8-7BMC Nephrology8

Mutant Huntingtin induces activation of the Bcl-2/adenovirus E1B 19-kDa interacting protein (BNip3)

Huntington's disease (HD) is a neurodegenerative disorder characterized by progressive neuronal death in the basal ganglia and cortex. Although increasing evidence supports a pivotal role of mitochondrial dysfunction in the death of patients' neurons, the molecular bases for mitochondrial impairment have not been elucidated. We provide the first evidence of an abnormal activation of the Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (BNip3) in cells expressing mutant Huntingtin. In this study, we show an abnormal accumulation and dimerization of BNip3 in the mitochondria extracted from human HD muscle cells, HD model cell cultures and brain tissues from HD model mice. Importantly, we have shown that blocking BNip3 expression and dimerization restores normal mitochondrial potential in human HD muscle cells. Our data shed light on the molecular mechanisms underlying mitochondrial dysfunction in HD and point to BNip3 as a new potential target for neuroprotective therapy in HD

Harmful lifestyles' clustering among sexually active in-school adolescents in Zambia

<p>Abstract</p> <p>Background</p> <p>HIV is a leading cause of morbidity and mortality in Zambia. Like many other African nations with high HIV burden, heterosexual intercourse is the commonest mode of HIV spread. The estimation of prevalence and factors associated with sexual intercourse among in-school adolescents has potential to inform public health interventions aimed at reducing the burden of sex-related diseases in Zambia.</p> <p>Methods</p> <p>We carried out secondary analysis of the Zambia Global School-Based Health Survey (GSHS) 2004; a cross sectional survey that aims to study health-related behaviors among in-school adolescents. We estimated frequencies of relevant socio-demographic variables. The associations between selected explanatory variables and self-reported history of sexual intercourse within the last 12 months were assessed using logistic regression analysis.</p> <p>Results</p> <p>Data from 2136 in-school adolescents who participated in the Zambia Global School-Based Health Survey of 2004 were available for analysis. Out of these respondents, 13.4% reported that they had sexual intercourse in the past 12 months prior to the survey; 16.4% and 9.7% among males and females respectively. In multivariable logistic regression analysis, with age less than 15 years as the referent the adjusted odds ratio (AOR) of having engaged in sexual intercourse in adolescents of age 15 years, and those aged 16 years or more were 1.06 (95% CI 1.03–1.10) and 1.74 (95% 1.70–1.79) respectively. Compared to adolescents who had no close friends, adolescents who had one close friend were more likely to have had sexual intercourse, AOR = 1.28 (95% CI 1.24–1.32). Compared to adolescents who were not supervised by their parents, adolescents who were rarely or sometimes supervised by their parents were likely to have had sexual intercourse, and adolescents who were most of the time/always supervised by their parents were less likely to have had sexual intercourse; AORs 1.26 (95% CI 1.23–1.26) and 0.92 (95% CI 0.90–0.95) respectively. Compared to adolescents who did not smoke dagga, adolescents who smoked dagga 1 or 2 times, and those who smoked dagga 3 or more times in their lifetime were 70% and 25% more likely to have had sexual intercourse, respectively. Adolescents who drank alcohol in 1 or 2 days, and those who took alcohol in 3 or more days in a month preceding the survey were 12% and 9% more likely to have had sexual intercourse, respectively, compared to adolescents who did not drink alcohol in the 30 days prior to the survey. Furthermore, adolescents who had been drunk 1 or 2 times, and who had been drunk 3 or more times in a life time were 14% and 13% more likely to have had sexual intercourse compared to those who have never been drunk in their lifetime.</p> <p>Conclusion</p> <p>We identified a constellation of potentially harmful behaviours among adolescents in Zambia. Public health interventions aimed at reducing prevalence of sexual intercourse may be designed and implemented in a broader sense having recognized that sexually active adolescents may also be exposed to other problem behaviours.</p

Circadian Clock Gene Expression in the Coral Favia fragum over Diel and Lunar Reproductive Cycles

Natural light cycles synchronize behavioral and physiological cycles over varying time periods in both plants and animals. Many scleractinian corals exhibit diel cycles of polyp expansion and contraction entrained by diel sunlight patterns, and monthly cycles of spawning or planulation that correspond to lunar moonlight cycles. The molecular mechanisms for regulating such cycles are poorly understood. In this study, we identified four molecular clock genes (cry1, cry2, clock and cycle) in the scleractinian coral, Favia fragum, and investigated patterns of gene expression hypothesized to be involved in the corals' diel polyp behavior and lunar reproductive cycles. Using quantitative PCR, we measured fluctuations in expression of these clock genes over both diel and monthly spawning timeframes. Additionally, we assayed gene expression and polyp expansion-contraction behavior in experimental corals in normal light:dark (control) or constant dark treatments. Well-defined and reproducible diel patterns in cry1, cry2, and clock expression were observed in both field-collected and the experimental colonies maintained under control light:dark conditions, but no pattern was observed for cycle. Colonies in the control light:dark treatment also displayed diel rhythms of tentacle expansion and contraction. Experimental colonies in the constant dark treatment lost diel patterns in cry1, cry2, and clock expression and displayed a diminished and less synchronous pattern of tentacle expansion and contraction. We observed no pattern in cry1, cry2, clock, or cycle expression correlated with monthly spawning events suggesting these genes are not involved in the entrainment of reproductive cycles to lunar light cycles in F. fragum. Our results suggest a molecular clock mechanism, potentially similar to that in described in fruit flies, exists within F. fragum

Regression of target organ damage in children and adolescents with primary hypertension

We assessed the effects of 12 months of non-pharmacological and pharmacological therapy on 24-h ambulatory blood pressure, regression of target organ damage (TOD) and metabolic abnormalities in 86 children (14.1 ± 2.4 years) with primary hypertension. Twenty-four hour systolic and diastolic blood pressure (BP) decreased (130 ± 8 vs 126 ± 8, 73 ± 7 vs 70 ± 7, p = 0.0001 and 0.004 respectively). Body mass index (BMI) did not change, but waist-to-hip (0.85 ± 0.07 vs 0.83 ± 0.05, p = 0.01) and waist-to-height ratio (WHtR; 0.49 ± 0.07 vs 0.48 ± 0.05, p = 0.008) decreased. Left ventricular mass index (LVMi; 38.5 ± 10.7 vs 35.2 ± 7.5 g/m2.7, p = 0.0001), prevalence of left ventricular hypertrophy (46.5% vs 31.4%; p = 0.0001), carotid intima-media thickness (cIMT; 0.44 ± 0.05 vs 0.42 ± 0.04 mm, p = 0.0001), wall cross sectional area (WCSA; 7.5 ± 1.3 vs 6.9 ± 1.2 mm2, p = 0.002), hsCRP (1.1 ± 1.0 vs 0.7 ± 0.7 mg/l, p = 0.002), and LDL-cholesterol (115 ± 33 vs 107 ± 26 mg/dl, p = 0.001) decreased. Patients who had lowered BP had a lower cIMT at the second examination (0.41 ± 0.04 vs 0.43 ± 0.04 mm, p = 0.04) and lower initial hsCRP values (0.9 ± 0.7 vs 1.5 ± 1.3 mg/l, p = 0.04) in comparison to non-responders. Regression analysis revealed that the main predictor of LVMi decrease was a decrease in abdominal fat expressed as a decrease in waist circumference (WC) (R2 = 0.280, β = 0.558, p = 0.005), for WCSA-SDS a decrease in WC (R2 = 0.332, β = 0.611, p = 0.009) and for a cIMT-SDS decrease the main predictor was a decrease in hsCRP concentrations (R2 = 0.137, β = 0.412, p = 0.03). Standard antihypertensive treatment lowered BP and led to regression of TOD in hypertensive children. Lean body mass increase and decrease in abdominal obesity correlated with TOD regression

Bnip3 as a Dual Regulator of Mitochondrial Turnover and Cell Death in the Myocardium

The Bcl-2 adenovirus E1B 19 kDa-interacting protein 3 (Bnip3) is a pro-apoptotic BH3-only protein associated with the pathogenesis of many diseases, including cancer and cardiovascular disease. Studies over the past decade have provided insight into how Bnip3 induces mitochondrial dysfunction and subsequent cell death in cells. More recently, Bnip3 was identified as a potent inducer of autophagy in cells. However, the functional role of Bnip3-mediated autophagy has been difficult to define and remains controversial. New evidence has emerged suggesting that Bnip3 is an important regulator of mitochondrial turnover via autophagy in the myocardium. Also, studies suggest that the induction of Bnip3-dependent mitochondrial autophagy is a separately activated process independent of Bax/Bak and the mitochondrial permeability transition pore (mPTP). This review discusses the current understanding of the functional role that Bnip3 plays in the myocardium. Recent studies suggest that Bnip3 might have a dual function in the myocardium, where it regulates both mitochondrial turnover via autophagy and cell death and that these are two separate processes activated by Bnip3

Which New Approaches to Tackling Neglected Tropical Diseases Show Promise?

This PLoS Medicine Debate examines the different approaches that can be taken to tackle neglected tropical diseases (NTDs). Some commentators, like Jerry Spiegel and colleagues from the University of British Columbia, feel there has been too much focus on the biomedical mechanisms and drug development for NTDs, at the expense of attention to the social determinants of disease. Burton Singer argues that this represents another example of the inappropriate “overmedicalization” of contemporary tropical disease control. Peter Hotez and colleagues, in contrast, argue that the best return on investment will continue to be mass drug administration for NTDs