The effects of a ketogenic diet on ATP concentrations and the number of hippocampal mitochondria in Aldh5a1 mice

Background

Succinic semialdehyde dehydrogenase (SSADH) deficiency is an inborn error of GABA metabolism characterized clinically by ataxia, psychomotor retardation and seizures. A mouse model of SSADH deficiency, the Aldh5a1^−/− mouse, has been used to study the pathophysiology and treatment of this disorder. Recent work from our group has shown that the ketogenic diet (KD) is effective in normalizing the Aldh5a1^−/− phenotype, although the mechanism of the effect remains unclear.

Methods

Here, we examine the effects of a KD on the number of hippocampal mitochondria as well as on ATP levels in hippocampus. Electron microscopy was performed to determine the number of mitochondria in the hippocampus of Aldh5a1^−/− mice. Adenosine triphosphate (ATP) levels were measured in hippocampal extracts.

Results

Our results show that the KD increases the number of mitochondria in Aldh5a1^−/− mice. We also show that Aldh5a1^−/− mice have significant reductions in hippocampal ATP levels as compared to controls, and that the KD restores ATP in mutant mice to normal levels.

General significance

Taken together, our data suggest that the KD's actions on brain mitochondria may play a role in the diet's ability to treat murine SSADH deficiency.     

Recycled paper products as substitutes for gelling agent in screwworm (Diptera: Calliphoridae) larval diet

Absorbent recycled paper products were tested and compared with a sodium polyacrylate gelling agent, Aquatain, for solidifying larval diets of the screwworm, Cochliomyia hominivorax (Coquerel). A recycled newsprint product, Terra-Mulch, when mixed with water and dietary ingredients produced a diet medium of homogeneous texture that supported larval growth and development comparable to the standard diet prepared with the gelling agent. Biological yields as calculated from number of pupae per tray from both the diets were similar. Three other types of recycled paper products were tested. Although less homogeneous in texture, these diets were as good as the diet with Terra-Mulch. There were no significant differences in the mean larval and pupal weights, no. of pupae/tray, percent emergence, oviposition, percent hatch, and percent longevity. When tests were conducted through eight consecutive generations, no adverse effect was noticed in any of the life history parameters. Terra-Mulch is inexpensive and biodegradable compared with the gelling agent Aquatain that is expensive and not biodegradable. Replacing Aquatain with Terra-Mulch in the screwworm larval diet for mass rearing may result in an annual savings of more than half a million U.S. dollars in costs of material and labor.     

Regulation of Notch1 and Dll4 by vascular endothelial growth factor in arterial endothelial cells: implications for modulating arteriogenesis and angiogenesis

Notch and its ligands play critical roles in cell fate determination. Expression of Notch and ligand in vascular endothelium and defects in vascular phenotypes of targeted mutants in the Notch pathway have suggested a critical role for Notch signaling in vasculogenesis and angiogenesis. However, the angiogenic signaling that controls Notch and ligand gene expression is unknown. We show here that vascular endothelial growth factor (VEGF) but not basic fibroblast growth factor can induce gene expression of Notch1 and its ligand, Delta-like 4 (Dll4), in human arterial endothelial cells. The VEGF-induced specific signaling is mediated through VEGF receptors 1 and 2 and is transmitted via the phosphatidylinositol 3-kinase/Akt pathway but is independent of mitogen-activated protein kinase and Src tyrosine kinase. Constitutive activation of Notch signaling stabilizes network formation of endothelial cells on Matrigel and enhances formation of vessel-like structures in a three-dimensional angiogenesis model, whereas blocking Notch signaling can partially inhibit network formation. This study provides the first evidence for regulation of Notch/Delta gene expression by an angiogenic growth factor and insight into the critical role of Notch signaling in arteriogenesis and angiogenesis.     

Distinct dynamical patterns that distinguish willed and forced actions

The neural pathways for generating willed actions have been increasingly investigated since the famous pioneering work by Benjamin Libet on the nature of free will. To better understand what differentiates the brain states underlying willed and forced behaviours, we performed a study of chosen and forced actions over a binary choice scenario. Magnetoencephalography recordings were obtained from six subjects during a simple task in which the subject presses a button with the left or right finger in response to a cue that either (1) specifies the finger with which the button should be pressed or (2) instructs the subject to press a button with a finger of their own choosing. Three independent analyses were performed to investigate the dynamical patterns of neural activity supporting willed and forced behaviours during the preparatory period preceding a button press. Each analysis offered similar findings in the temporal and spatial domains and in particular, a high accuracy in the classification of single trials was obtained around 200 ms after cue presentation with an overall average of 82%. During this period, the majority of the discriminatory power comes from differential neural processes observed bilaterally in the parietal lobes, as well as some differences in occipital and temporal lobes, suggesting a contribution of these regions to willed and forced behaviours.     

Impact of naturally occurring variants of HCV protease on the binding of different classes of protease inhibitors

HCV drug discovery efforts have largely focused on genotype 1 virus due to its prevalence and relatively poor response to current therapy. However, patients infected with genotype 2 and 3 viruses account for a significant number of cases and would also benefit from new therapies. In vitro studies using two chemically distinct protease inhibitors with clinical potential showed that one, VX-950, was equally active on proteases from all three genotypes, whereas the other, BILN 2061, was significantly less active on genotype 2 and 3 proteases. Naturally occurring variation near the inhibitor binding site was identified based on sequence alignment of the protease region from genotype 1-3 sequences. Substitution of amino acids in genotype 1 based on genotype 2 and 3 has revealed residues which impact binding of BILN 2061. Substitution of residues 78-80, together with 122 and 132, accounted for most of the reduced sensitivity of genotype 2. The most critical position affecting inhibitor binding to genotype 3 protease was 168. Substitution of residues at positions 168, 123, and 132 fully accounted for the reduced sensitivity of genotype 3. Comparative studies of BILN 2061 and a closely related nonmacrocycle inhibitor suggested that the rigidity of BILN 2061, while conferring greater potency against genotype 1, rendered it more sensitive to variations near the binding site. Free energy perturbation analysis confirmed the experimental observations. The identification of naturally occurring variations which can affect inhibitor binding is an important step in the design of broad-spectrum, second generation protease inhibitors.     

Identification of highly transformable wheat genotypes for mass production of fertile transgenic plants.

The efficiency of wheat biolistic transformation systems strongly depends on the bombardment parameters, the condition of the donor plant, and the plant genotype chosen for the transformation process. This paper analyzes the transformation efficiency of the 129 wheat sister lines generically called 'Bobwhite', originally obtained from the cross 'Aurora'//'Kalyan'/'Bluebird 3'/'Woodpecker'. A number of factors influencing the transformation were examined, such as the ability to produce embryogenic callus, regeneration in selection medium, and overall transformation performance. Of the 129 genotypes evaluated, eight demonstrated transformation efficiencies above 60% (60 independent transgenic events per 100 immature embryos bombarded). Among the eight genotypes identified, we studied agronomic characteristics such as earliness to identify the most adaptable line(s) for different lab conditions. 'Bobwhite' SH 98 26 was identified as a super-transformable wheat line.     

Minimum population size estimates demonstrate an increase in southern elephant seals (Mirounga leonina) on Livingston Island, maritime Antarctica

Southern elephant seals (Mirounga leonina) are apex predators of marine Antarctic food webs, and variations in their populations have been linked to environmental changes. Consequently, measuring and reporting the status of elephant seal populations provide insights into the environmental status of Antarctica. Here, we present new information on the size of the elephant seal subpopulation on Byers Peninsula (Livingston Island, South Shetland Islands, maritime Antarctica). Based on a total count of 1,510 pups, we estimated a total subpopulation size of 5,530 individuals by using a conversion factor of 3.5. This represents an increase of 150 % since the subpopulation was first counted 30 years ago. Based on this finding, we hypothesize that the overall South Georgia stock, to which the subpopulation we estimated on Byers Peninsula belongs, could be increasing instead of remaining stable as previously thought.     

Early impairment of myocardial deformation assessed by regional speckle-tracking echocardiography in the indeterminate form of Chagas disease without fibrosis detected by cardiac magnetic resonance

Chagas disease (CD) will account for 200,000 cardiovascular deaths worldwide over the next 5 years. Early detection of chronic Chagas cardiomyopathy (CCC) is a challenge. We aimed to test if speckle-tracking echocardiography (STE) can detect incipient myocardial damage in CD. METHODS: Among 325 individuals with positive serological tests, 25 (age 55±12yrs) were selected to compose the group with indeterminate form of Chagas disease (IFCD), based on stringent criteria of being asymptomatic and with normal EKG/X-ray studies. This group was compared with a group of 20 patients with CCC (55±11yrs) and a group of 20 non-infected matched control (NC) subjects (48±10yrs). CD patients and NC were submitted to STE and CD patients were submitted to cardiac magnetic resonance (CMR) with late gadolinium administration to detect cardiac fibrosis by the late enhancement technique. Global longitudinal strain (GLS), circumferential (GCS) and radial strain (GRS) were defined as the average of segments measured from three apical view (GLS) and short axis views (GRS and GCS). Regional left ventricular (LV) longitudinal strain (Reg LS) was measured from each of the 17 segments. Twist was measured as systolic peak difference between basal and apical rotation and indexed to LV length to express torsion. RESULTS: STE global indices (GLS, GCS, twist and torsion) were reduced in CCC vs NC (GLS: -14±6.3% vs -19.3±1.6%, p = 0.001; GCS: -13.6±5.2% vs -17.3 ±2.8%; p = 0.008; twist: 8±7° vs 14±7°, p = 0.01 and torsion: 0.96±1°/cm vs 1.9±1°/cm, p = 0.005), but showed no differences in IFCD vs NC. RegLS was reduced in IFCD vs NC in four LV segments: basal-inferior (-16.3±3.3% vs -18.6±2.2%, p = 0.013), basal inferoseptal (-13.1±3.4 vs -15.2±2.7, p = 0.019), mid-inferoseptal (-17.7±3.2 vs -19.4±2, p = 0.032) and mid-inferolateral (-15.2±3.5 vs -17.8±2.8, p = 0.014). These abnormalities in RegLS occurred in the absence of myocardial fibrosis detectable with CMR in nearly 92% of subjects with IFCD, while myocardial fibrosis was present in 65% with CCC. CONCLUSION: RegLS detects early regional impairment of myocardial strain that is independent from fibrosis in IFCD subjects.     

Stem cell mobilization by hyperbaric oxygen

We hypothesized that exposure to hyperbaric oxygen (HBO(2)) would mobilize stem/progenitor cells from the bone marrow by a nitric oxide (*NO) -dependent mechanism. The population of CD34(+) cells in the peripheral circulation of humans doubled in response to a single exposure to 2.0 atmospheres absolute (ATA) O(2) for 2 h. Over a course of 20 treatments, circulating CD34(+) cells increased eightfold, although the overall circulating white cell count was not significantly increased. The number of colony-forming cells (CFCs) increased from 16 +/- 2 to 26 +/- 3 CFCs/100,000 monocytes plated. Elevations in CFCs were entirely due to the CD34(+) subpopulation, but increased cell growth only occurred in samples obtained immediately posttreatment. A high proportion of progeny cells express receptors for vascular endothelial growth factor-2 and for stromal-derived growth factor. In mice, HBO(2) increased circulating stem cell factor by 50%, increased the number of circulating cells expressing stem cell antigen-1 and CD34 by 3.4-fold, and doubled the number of CFCs. Bone marrow *NO concentration increased by 1,008 +/- 255 nM in association with HBO(2). Stem cell mobilization did not occur in knockout mice lacking genes for endothelial *NO synthase. Moreover, pretreatment of wild-type mice with a *NO synthase inhibitor prevented the HBO(2)-induced elevation in stem cell factor and circulating stem cells. We conclude that HBO(2) mobilizes stem/progenitor cells by stimulating *NO synthesis.