Blunt Traumatic Aortic Injury of Right Aortic Arch in a Patient with an Aberrant Left Subclavian Artery

Right-sided aortic arch (RAA) is a rare congenital developmental variant present in about 0.1 percent of the population. This anatomical anomaly is commonly associated with congenital heart disease and complications from compression of mediastinal structures. However, it is unknown if patients are at a higher risk of blunt thoracic aortic injury (BTAI). We report a case of a 20-year-old man admitted to the hospital after being hit by an automobile. Computed tomographic scan revealed an RAA with an aberrant left subclavian artery originating from a Kommerell’s diverticulum. A pseudo-aneurysm was also seen along the aortic arch. A diagnosis of blunt traumatic aortic injury was made. The patient was successfully treated with a 26mm Vascutek hybrid stentgraft using the frozen elephant trunk technique.A literature review of the pathophysiology of BTAI was performed to investigate if patients with right-sided aortic arch are at a higher risk of suffering from BTAI. Results from the review suggest that although theoretically there may be a higher risk of BTAI in RAA patients, the rarity of this condition has prevented large studies to be conducted. Previously reported cases of BTAI in RAA have highlighted the possibility that the aortic isthmus may be anatomically weak and therefore prone to injury. We have explored this possibility by reviewing current literature of the embryological origins of the aortic arch and descending aorta.     

Galectin-3 preserves renal tubules and modulates extracellular matrix remodeling in progressive fibrosis

Renal tubular cell apoptosis is a critical detrimental event that leads to chronic kidney injury in association with renal fibrosis. The present study was designed to investigate the role of galectin-3 (Gal-3), an important regulator of multiple apoptotic pathways, in chronic kidney disease induced by unilateral ureteral obstruction (UUO). After UUO, Gal-3 expression significantly increased compared with basal levels reaching a peak increase of 95-fold by day 7. Upregulated Gal-3 is predominantly tubular at early time points after UUO but shifts to interstitial cells as the injury progresses. On day 14, there was a significant increase in TdT-mediated dUTP nick end labeling-positive cells (129%) and cytochrome c release (29%), and a decrease in BrdU-positive cells (62%) in Gal-3-deficient compared with wild-type mice. The degree of renal damage was more extensive in Gal-3-deficient mice at days 14 and 21, 35 and 21% increase in total collagen, respectively. Despite more severe fibrosis, myofibroblasts were significantly decreased by 58% on day 14 in the Gal-3-deficient compared with wild-type mice. There was also a corresponding 80% decrease in extracellular matrix synthesis in Gal-3-deficient compared with wild-type mice. Endo180 is a recently recognized receptor for intracellular collagen degradation that is expressed by interstitial cells during renal fibrogenesis. Endo180 expression was significantly decreased by greater than 50% in Gal-3-deficient compared with wild-type mice. Taken together, these results suggested that Gal-3 not only protects renal tubules from chronic injury by limiting apoptosis but that it may lead to enhanced matrix remodeling and fibrosis attenuation.     

Oncaea praeclara n. sp. (Copepoda: Poecilostomatoida) from deep-sea hydrothermal vents in the eastern Pacific

A new species of planktonic copepod, Oncaea praeclara, is describedfrom a depth of 2003–2635 m at the East Pacific Rise,the Galapagos Rift, and the Guaymas Basin in the Gulf of California.The species may be recognized by a combination of characters:its relatively large size; the long caudal ramus, which is abouttwo times longer than the anal segment and has a ratio of 4.96–6.7:1;the sexual dimorphism in the armature of the fourth segmentof the second antenna; and the labrum with a nearly straightposteroventral margin having four median teeth and lateral setules.     

Distribution and life-cycle of Scottnema lindsayae (Nematoda) in Antarctic soils: a modeling analysis of temperature responses

A nested age within stage-structured model was developed to simulate Scottnema lindsayae population dynamics in soils of the McMurdo Dry Valleys, and used to evaluate responses of this species to a range of annual temperature regimes. Simulations predicted that many sites are unlikely to support S. lindsayae, consistent with field observations showing that many soils in the dry valleys lack nematodes. The simulated coefficient of population growth (5) varied as a roughly linear function of cumulative annual degree-days (>0°C), providing a possible index to site suitability for S. lindsayae that could be used in conjunction with remotely sensed energy data to estimate species distributions. Low temperatures, coupled with long lifespan and slow development of this species, may make dry-valley soil systems sensitive to perturbations that disrupt population dynamics. Indeed, sensitivity analysis indicated that factors affecting adult longevity were the most important determinants of model behavior, further emphasizing the potential impacts of disturbance on local populations.     

Sedimentation and intrinsic viscosity behavior of PM2 bacteriophage DNA in alkaline solution

The sedimentation coefficient and intrinsic viscosity of nicked and closed circular PM2 bacteriophage DNA have been measured as a function of pH in the alkaline region. A gradual increase in the sidimentation coefficient, and a corresponding decrease in the intrinsic viscosity, are observed for the superhelical (closed) circle in the pH region from 10.5 to about 10.9. This has been tentatively interpreted in terms of the known dependence of sedimentation coefficient upon the number of superhelical turns. At slightly higher pH values, the curve passes through the minimum (sedimentation coefficient) and maximum (intrinsic viscosity) expected when the superhelical turns present at neutral pH are unwound by partial alkaline denaturation. Sedimentation studies of the relaxed (nicked) circular species have revealed the existence of DNA forms in the pH region from 11.27 to 11.37 which sediment considerably faster than the closed circle in the same pH region. These have been identified as partially denatured nicked circles, in which varying fractions of the duplex structure have undergone alkaline denaturation, but strand separation has not yet occurred. Varying fractions of a slower species, either undenatured or completely denatured nicked circles, are also observed in some of these experiments. A corresponding result is observed in the intrinsic viscosity vs. pH curve. When nicked circular PM2 DNA is exposed to various alkaline pH's, rapidly neutralized, and sedimented at neutral pH, the expected sharp transition from native to denatured (strand-separated) molecules is seen. However, a very narrow pH range is noted in which native and denatured forms coexist in a single experiment. The above experiments carried out upon the closed form also reveal a narrow pH range in which the bulk of the transition from native closed circles to the collapsed cyclic coil takes place, in acccord with an earlier study on a different DNA. This transition is shown never to be completely effected, however, as there is a fraction (7–8%)of the closed circles which renature to the native form, regardless of the alkaline pH employed. This same phenomenon was not observed in the case of artificially closed λb₂b₅c DNA circles. Possible explanations for some of the above results are discussed.     

Influence of L-NAME on pulmonary O2 uptake kinetics during heavy-intensity cycle exercise.

We hypothesized that inhibition of nitric oxide synthase (NOS) by N(G)-nitro-L-arginine methyl ester (L-NAME) would alleviate the inhibition of mitochondrial oxygen uptake (Vo(2)) by nitric oxide and result in a speeding of phase II pulmonary Vo(2) kinetics at the onset of heavy-intensity exercise. Seven men performed square-wave transitions from unloaded cycling to a work rate requiring 40% of the difference between the gas exchange threshold and peak Vo(2) with and without prior intravenous infusion of L-NAME (4 mg/kg in 50 ml saline over 60 min). Pulmonary gas exchange was measured breath by breath, and Vo(2) kinetics were determined from the averaged response to two exercise bouts performed in each condition. There were no significant differences between the control (C) and L-NAME conditions (L) for baseline Vo(2), the duration of phase I, or the amplitude of the primary Vo(2) response. However, the time constant of the Vo(2) response in phase II was significantly smaller (mean +/- SE: C: 25.1 +/- 3.0 s; L: 21.8 +/- 3.3 s; P < 0.05), and the amplitude of the Vo(2) slow component was significantly greater (C: 240 +/- 47 ml/min; L: 363 +/- 24 ml/min; P < 0.05) after L-NAME infusion. These data indicate that inhibition of NOS by L-NAME results in a significant (13%) speeding of Vo(2) kinetics and a significant increase in the amplitude of the Vo(2) slow component in the transition to heavy-intensity cycle exercise in men. The speeding of the primary component Vo(2) kinetics after L-NAME infusion indicates that at least part of the intrinsic inertia to oxidative metabolism at the onset of heavy-intensity exercise may result from inhibition of mitochondrial Vo(2) by nitric oxide. The cause of the larger Vo(2) slow-component amplitude with L-NAME requires further investigation but may be related to differences in muscle blood flow early in the rest-to-exercise transition.