Tracking the oxidative kinetics of carbohydrates, amino acids and fatty acids in the house sparrow using exhaled \u3csup\u3e13\u3c/sup\u3eCO\u3csub\u3e2\u3c/sub\u3e

Clinicians commonly measure the 13CO2 in exhaled breath samples following administration of a metabolic tracer (breath testing) to diagnose certain infections and metabolic disorders. We believe that breath testing can become a powerful tool to investigate novel questions about the influence of ecological and physiological factors on the oxidative fates of exogenous nutrients. Here we examined several predictions regarding the oxidative kinetics of specific carbohydrates, amino acids and fatty acids in a dietary generalist, the house sparrow (Passer domesticus). After administering postprandial birds with 20 mg of one of seven 13C-labeled tracers, we measured rates of 13CO2 production every 15 min over 2 h. We found that sparrows oxidized exogenous amino acids far more rapidly than carbohydrates or fatty acids, and that different tracers belonging to the same class of physiological fuels had unique oxidative kinetics. Glycine had a mean maximum rate of oxidation (2021 nmol min−1) that was significantly higher than that of leucine (351 nmol min−1), supporting our prediction that nonessential amino acids are oxidized more rapidly than essential amino acids. Exogenous glucose and fructose were oxidized to a similar extent (5.9% of dose), but the time required to reach maximum rates of oxidation was longer for fructose. The maximum rates of oxidation were significantly higher when exogenous glucose was administered as an aqueous solution (122 nmol min−1), rather than as an oil suspension (93 nmol min−1), supporting our prediction that exogenous lipids negatively influence rates of exogenous glucose oxidation. Dietary fatty acids had the lowest maximum rates of oxidation (2-6 nmol min−1), and differed significantly in the extent to which each was oxidized, with 0.73%, 0.63% and 0.21% of palmitic, oleic and stearic acid tracers oxidized, respectively

Propranolol blocks ventricular refractory period changes with orthostatic stress in humans

The purpose of this study was to test the hypothesis that orthostatic stress shortens the right ventricular effective refractory period by reflex activation of beta-adrenergic receptors. Twelve patients undergoing electrophysiologic testing for standard clinical indications were studied. After a full electrophysiologic study, patients underwent graded lower body negative pressure before and after administration of either propranolol (0.2 mg/kg intravenously) in Group I or atropine (0.035 mg/kg intravenously) in Group II.Before the addition of drugs, lower body negative pressure produced decreases in systolic blood pressure and significant increases in sinus rate. The effective refractory period shortened from 214 ± 8 (mean ± SEM) to 206 ± 7 ms at −40 cm H2O and to 197 ± 4 ms at −60 cm H2O lower body negative pressure. After propranolol, Group I patients had no change in right ventricular effective refractory period despite similar changes in sinus rate and systolic blood pressure. In Group II patients, atropine did not alter effective refractory period responses to lower body negative pressure.Thus, reflex adjustments to orthostatic stress result in shortening of right ventricular effective refractory period mediated by way of beta-adrenergic mechanisms. These findings constitute the first evidence that sympathetic influences mobilized by the body can directly modulate ventricular electrophysiologic changes

Comprehensive Family Hygiene Promotion in Peri-Urban Cape Town: Reduction of Respiratory Illness in Children Under Five

Background: Examination with Cone Beam CT (CBCT) is common for localizing maxillary canines with eruption disturbance. The benefits and costs of these examinations are unclear. Objectives: To measure: 1. the proportion of orthodontists' treatment decisions that were different based on intraoral and panoramic radiography (M1) compared with CBCT and panoramic radiography (M2); and 2. the costs of producing different treatment plans, regarding patients with maxillary canines with eruption disturbance. Subjects and methods: Orthodontists participated in a web-based survey and were randomly assigned to denote treatment decisions and the level of confidence in this decision for four patient cases presented with M1 or M2 at two occasions for the same patient case. Results: One hundred and twelve orthodontists made 445 assessments based on M1 and M2, respectively. Twenty-four per cent of the treatment decisions were different depending on which method the raters had access to, whereof one case differed significantly from all other cases. The mean total cost per examination was €99.84 using M1 and €134.37 using M2, resulting in an incremental cost per examination of €34.53 for M2. Limitations: Benefits in terms of number of different treatment decisions must be considered as an intermediate outcome for the effectiveness of a diagnostic method and should be interpreted with caution. Conclusions: For the patient cases presented in this study, most treatment decisions were the same irrespective of radiological method. Accordingly, this study does not support routine use of CBCT regarding patients with maxillary canine with eruption disturbance

The tricarboxylic acid cycle in Shewanella oneidensis is independent of Fur and RyhB control

Background: It is well established in E. coli and Vibrio cholerae that strains harboring mutations in the ferric uptake regulator gene (fur) are unable to utilize tricarboxylic acid (TCA) compounds, due to the down-regulation of key TCA cycle enzymes, such as AcnA and SdhABCD. This down-regulation is mediated by a Fur-regulated small regulatory RNA named RyhB. It is unclear in the gamma proteobacterium S. oneidensis whether TCA is also regulated by Fur and RyhB. Results: In the present study, we showed that a fur deletion mutant of S. oneidensis could utilize TCA compounds. Consistently, expression of the TCA cycle genes acnA and sdhA was not down-regulated in the mutant. To explore this observation further, we identified a ryhB gene in Shewanella species and experimentally demonstrated the gene expression. Further experiments suggested that RyhB was up-regulated in fur mutant, but that AcnA and SdhA were not controlled by RyhB. Conclusions: These cumulative results delineate an important difference of the Fur-RyhB regulatory cycle between S. oneidensis and other gamma-proteobacteria. This work represents a step forward for understanding the unique regulation in S. oneidensis

The Lake Edgar Fault: an active fault in Southwestern Tasmania, Australia, with repeated displacement in the Quaternary

The Lake Edgar Fault in Western Tasmania, Australia is marked by a prominent fault scarp and is a recently reactivated fault initially of Cambrian age. The scarp has a northerly trend and passes through the western abutment of the Edgar Dam, a saddle dam on Lake Pedder. The active fault segment displaces geologically young river and glacial deposits. It is 29 ± 4 km long, and dips to the west. Movement on the fault has ruptured the ground surface at least twice within the Quaternary and possibly the last ca. 25 000 years; the most recent rupture has occurred since the last glaciation (within the last ca. 10000 years). This is the only known case of surface faulting in Australia with evidence for repeated ruptures in the Late Pleistocene. Along its central portion the two most recent surface-faulting earthquakes have resulted in about 2.5 m of vertical displacement each (western side up). The Lake Edgar Fault is considered capable of generating earthquakes in the order of magnitude 61/2-71/4. The Gell River Fault is another fault nearby that was apparently also active in the Late Pleistocene. It has yet to be studied in detail but the scarp appears to be more degraded and therefore older than the most recent movement on the Lake Edgar Fault

Introduced and Native Congeners Use Different Resource Allocation Strategies to Maintain Performance During Infection

Hosts can manage parasitic infections using an array of tactics, which are likely to vary contingent on coevolutionary history between the host and the parasite. Here we asked whether coping ability of congeners that differ in host-parasite coevolutionary history differed in response to experimental infections with a coccidian parasite. House sparrows (Passer domesticus) and gray-headed sparrows (Passer griseus) are sympatric and ecologically similar, but house sparrows are recent colonizers of Kenya, the site of our comparison, whereas gray-headed sparrows are native. We evaluated three variables as barometers of infection coping ability: vertical flight, pectoral muscle size, and fat score. We also measured routing of a dose of 13C-labeled leucine, an essential amino acid, among tissues to compare resource allocation strategies in response to infection. We found that burden effects on performance were minimal in both species, but house sparrows maintained considerably higher burdens than gray-headed sparrows regardless of exposure. House sparrows also had more exogeneous leucine tracer in all tissues after 24 h, demonstrating a difference in the way the two species allocate or distribute resources. We argue that house sparrows may be maintaining larger resource reserves to mitigate costs associated with exposure and infection. Additionally, in response to increased parasite exposure, gray-headed sparrows had less leucine tracer in their spleens and more in their gonads, whereas house sparrows did not change allocation, perhaps indicating a trade-off that is not experienced by the introduced species

Dynamics of epigenetic regulation at the single-cell level

Chromatin regulators play a major role in establishing and maintaining gene expression states. Yet how they control gene expression in single cells, quantitatively and over time, remains unclear. We used time-lapse microscopy to analyze the dynamic effects of four silencers associated with diverse modifications: DNA methylation, histone deacetylation, and histone methylation. For all regulators, silencing and reactivation occurred in all-or-none events, enabling the regulators to modulate the fraction of cells silenced rather than the amount of gene expression. These dynamics could be described by a three-state model involving stochastic transitions between active, reversibly silent, and irreversibly silent states. Through their individual transition rates, these regulators operate over different time scales and generate distinct types of epigenetic memory. Our results provide a framework for understanding and engineering mammalian chromatin regulation and epigenetic memory

Meeting Funders’ Data Policies: Blueprint for a Research Data Management Service Group (RDMSG)

This report summarizes the elements that we expect to be required in data management plans, describes Cornell’s current capabilities and needs in meeting such requirements, and proposes a structure for a virtual organization that builds on the collaboration between the DRSG, CAC, CUL and CISER. The proposed organization also includes Cornell Information Technologies (CIT) and Weill Cornell Medical College Information Technologies and Services (WCMC-ITS) to further develop and provide this support