Radiation-induced signaling results in mitochondrial impairment in mouse heart at 4 weeks after exposure to X-rays

BACKROUND: Radiation therapy treatment of breast cancer, Hodgkin's disease or childhood cancers expose the heart to high local radiation doses, causing an increased risk of cardiovascular disease in the survivors decades after the treatment. The mechanisms that underlie the radiation damage remain poorly understood so far. Previous data show that impairment of mitochondrial oxidative metabolism is directly linked to the development of cardiovascular disease. METHODOLOGY/PRINCIPAL FINDINGS: In this study, the radiation-induced in vivo effects on cardiac mitochondrial proteome and function were investigated. C57BL/6N mice were exposed to local irradiation of the heart with doses of 0.2 Gy or 2 Gy (X-ray, 200 kV) at the age of eight weeks, the control mice were sham-irradiated. After four weeks the cardiac mitochondria were isolated and tested for proteomic and functional alterations. Two complementary proteomics approaches using both peptide and protein quantification strategies showed radiation-induced deregulation of 25 proteins in total. Three main biological categories were affected: the oxidative phophorylation, the pyruvate metabolism, and the cytoskeletal structure. The mitochondria exposed to high-dose irradiation showed functional impairment reflected as partial deactivation of Complex I (32%) and Complex III (11%), decreased succinate-driven respiratory capacity (13%), increased level of reactive oxygen species and enhanced oxidation of mitochondrial proteins. The changes in the pyruvate metabolism and structural proteins were seen with both low and high radiation doses. CONCLUSION/SIGNIFICANCE: This is the first study showing the biological alterations in the murine heart mitochondria several weeks after the exposure to low- and high-dose of ionizing radiation. Our results show that doses, equivalent to a single dose in radiotherapy, cause long-lasting changes in mitochondrial oxidative metabolism and mitochondria-associated cytoskeleton. This prompts us to propose that these first pathological changes lead to an increased risk of cardiovascular disease after radiation exposure.     

Metal ion coordination to 2′ functionality of guanosine mediates substrate-guanosine coupling in group I ribozymes: implications for conserved role of metal ions and for variability in RNA folding in ribozyme catalysis

Divalent metal ions are necessary in the self splicing reaction of group I introns, and we report that metal interaction to the 2′ position of guanosine for the Azoarcus ribozyme is required for catalysis. Moreover, this metal coordination promotes the guanosine-substrate coupled binding to the ribozyme, which is another conserved feature seen across phylogenetic boundaries. Typically there is a 4-9-fold difference in binding of G to E_free versus E · S. In the Tetrahymena ribozyme’s case this substrate-guanosine communication was attributed to conformational change(s) that lead to cooperative binding of the two cofactors which is almost nonexistent at low temperatures (4 °C). In the prokaryotic Azoarcus ribozyme we also see a 4-5-fold difference in binding of the guanosine/substrate to E_free versus E · G or E · S at 10 °C that is attributed to guanosine-substrate coupling. This coupling is diminished when the metal (Mg²⁺) coordination to the 2′ is disrupted with use of 2′-amino-2′-deoxyguanosine. The coupling is restored when softer Mn²⁺ ions are added to the buffer. This evidence generalizes a model for group I ribozyme catalysis that involves metal coordination to the 2′ position of guanosine. However, we see one striking difference in that the guanosine-substrate coupling is reversed. In the Azoarcus system (10 °C) the guanosine/substrate binds 5-fold more tightly to E_free than to E · S or E · G, which is the opposite for Tetrahymena even when the later is run at 4 °C. One implication for this difference in coupling is that the Azoarcus is in a folded state well accommodated for guanosine or substrate binding. This initial binding actually causes a conformational change that retards the subsequent binding of the second cofactor, which contrasts what was found for the Tetrahymena ribozyme. These results indicate that while the role for the metal ions in the chemical catalysis is conserved across phylogenetic boundaries, there is variability in the folding pattern of the ribozyme that leads to phosphoryl transfer.     

Studies on the Mode of Membrane Interaction of C-terminally Amidated Brevinin1 HYba1 and 2 Peptides Against Bacteria

In this study, we investigated the possible mode of action of two C-terminally amidated novel peptides identified from the frog skin on both Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Vibrio cholerae). The results indicate that the peptides initially induce membrane depolarization followed by pore formation in a concentration-dependent manner. A microscopic examination revealed the fact that the peptides are capable of destroying bacterial cells physically. The activity of these peptides against Gram-negative bacteria was dependent on the presence of divalent cations (Ca²⁺ and Mg²⁺) but not in Gram-positive bacteria. This study also emphasizes that the endemic frogs of the Western Ghats may provide a valuable source of its skin peptides having the potential for further improvement as lead drug molecules.     

Relative dominance of Gag p24-specific cytotoxic T lymphocytes is associated with human immunodeficiency virus control

Conflicting data on the role of total virus- and protein-specific cytotoxic-T-lymphocyte (CTL) responses in the control of human immunodeficiency virus (HIV) disease progression exist. We present data generated from a Peruvian cohort of untreated, clade B-infected subjects, demonstrating that the proportion of Gag-specific, and in particular p24-reactive, CTL responses among the total virus-specific CTL activity is associated with individuals' CD4 counts and viral loads. Analyses in a second cohort in the United States confirm these findings and point towards a dominant role of Gag-specific immunity in effective control of HIV infection, providing important guidance for HIV vaccine development.     

Transvaginal ultrasonographic (TVS) evaluation of baboon gestation from 37–62 days postconception

Our objective was to determine the growth of the embryo and surrounding structures during baboon (Papio anubis) gestation using transvaginal sonography (TVS). To this end, we evaluated 19 timed-mated baboons using TVS between 37 and 62 days of gestation. After visualization of the gestational sac, amniotic sac, and yolk sac, the three largest diameters of each of these extra embryonic structures were measured using longitudinal and transverse views. Embryonic crown–rump length (CRL) was also recorded. Embryonic heart rates were determined using the M-mode function of the ultrasound equipment. All 19 gestations developed without complications. No significant trend could be demonstrated for heart rate or yolk sac diameters over the 37–62 day gestational age period. Mean (SD) gestational age in days, heart rate, and yolk sac diameter, respectively, for the group were 48 (7.8) days (range: 37–61), 180 (15) beats per minute (range: 156–221) and 5 (0.1) mm (range: 3–8). Significant correlations (P < 0.0001) were determined between gestational age and CRL and gestational and amniotic sacs. We conclude that TVS allows a clear visualization of the embryo proper and all the cavities within the gestational sac of the baboon gestation. This study has determined the normal pattern of changes of these cavities from 37–62 days of gestation. Future applications of these findings may include sampling fluid from these cavities for biochemical, cytological, and metabolic studies. Am. J. Primatol. 43:323–328, 1997. © 1997 Wiley-Liss, Inc.     

How Far Are We from Visceral Leishmaniasis Elimination in Bangladesh? An Assessment of Epidemiological Surveillance Data

Introduction

In 2005, Bangladesh, India, and Nepal joined forces to eliminate Visceral Leishmaniasis (or kala-azar) from the region by 2015. In Bangladesh the elimination target is set at less than one new case per 10,000 population per year at upazila (sub-district) level. As the deadline approaches, we review the status of the elimination initiative in this country.

Methods

We collected all available disease surveillance data at the Disease Control Unit of the Directorate General of Health Services, Government of Bangladesh from 1994 to 2013. Additionally, we retrieved data from the Civil Surgeon Office from the Mymensingh district, one of the most heavily affected areas in Bangladesh.

Results

Between 1994 and 2013, 109,266 kala-azar cases causing 329 deaths were reported from 37 endemic districts in Bangladesh. Only 16 districts reported cases every year. The Mymensingh district was the most affected with 53,582 (49.04%) cases. Between 2008 and 2013 only 16 upazilas showed incidence rates above the elimination target in which they ranged from 1.06 to 18.25 per 10,000 people per year.

Discussion

While clear progress has been made towards eliminating VL, 16 upazilas in Bangladesh had not yet reached the target in 2013, based on official notification data that probably suffered from under-reporting bias. The elimination initiative urgently needs to establish methods to ascertain and monitor the elimination target.     

Regional-Specific Effects of Ovarian Hormone Loss on Synaptic Plasticity in Adult Human APOE Targeted Replacement Mice

The human apolipoprotein ε4 allele (APOE4) has been implicated as one of the strongest genetic risk factors associated with Alzheimer’s disease (AD) and in influencing normal cognitive functioning. Previous studies have demonstrated that mice expressing human apoE4 display deficits in behavioral and neurophysiological outcomes compared to those with apoE3. Ovarian hormones have also been shown to be important in modulating synaptic processes underlying cognitive function, yet little is known about how their effects are influenced by apoE. In the current study, female adult human APOE targeted replacement (TR) mice were utilized to examine the effects of human APOE genotype and long-term ovarian hormone loss on synaptic plasticity in limbic regions by measuring dendritic spine density and electrophysiological function. No significant genotype differences were observed on any outcomes within intact mice. However, there was a significant main effect of genotype on total spine density in apical dendrites in the hippocampus, with post-hoc t-tests revealing a significant reduction in spine density in apoE3 ovariectomized (OVX) mice compared to sham operated mice. There was also a significant main effect of OVX on the magnitude of LTP, with post-hoc t-tests revealing a decrease in apoE3 OVX mice relative to sham. In contrast, apoE4 OVX mice showed increased synaptic activity relative to sham. In the lateral amygdala, there was a significant increase in total spine density in apoE4 OVX mice relative to sham. This increase in spine density was consistent with a significant increase in spontaneous excitatory activity in apoE4 OVX mice. These findings suggest that ovarian hormones differentially modulate synaptic integrity in an apoE-dependent manner within brain regions that are susceptible to neurophysiological dysfunction associated with AD.