Coherent Stranski-Krastanov growth in 1+1 dimensions with anharmonic interactions: An equilibrium study

The formation of coherently strained three-dimensional islands on top of the wetting layer in Stranski-Krastanov mode of growth is considered in a model in 1+1 dimensions accounting for the anharmonicity and non-convexity of the real interatomic forces. It is shown that coherent 3D islands can be expected to form in compressed rather than in expanded overlayers beyond a critical lattice misfit. In the latter case the classical Stranski-Krastanov growth is expected to occur because the misfit dislocations can become energetically favored at smaller island sizes. The thermodynamic reason for coherent 3D islanding is the incomplete wetting owing to the weaker adhesion of the edge atoms. Monolayer height islands with a critical size appear as necessary precursors of the 3D islands. The latter explains the experimentally observed narrow size distribution of the 3D islands. The 2D-3D transformation takes place by consecutive rearrangements of mono- to bilayer, bi- to trilayer islands, etc., after exceeding the corresponding critical sizes. The rearrangements are initiated by nucleation events each next one requiring to overcome a lower energetic barrier. The model is in good qualitative agreement with available experimental observations.Comment: 12 pages text, 15 figures, Accepted in Phys.Rev.B, Vol.61, No2

Critical Limb Ischemia

Critical limb ischemia (CLI), defined as chronic ischemic rest pain, ulcers, or gangrene attributable to objectively proven arterial occlusive disease, is the most advanced form of peripheral arterial disease. Traditionally, open surgical bypass was the only effective treatment strategy for limb revascularization in this patient population. However, during the past decade, the introduction and evolution of endovascular procedures have significantly increased treatment options. In a certain subset of patients for whom either surgical or endovascular revascularization may not be appropriate, primary amputation remains a third treatment option. Definitive high-level evidence on which to base treatment decisions, with an emphasis on clinical and cost effectiveness, is still lacking. Treatment decisions in CLI are individualized, based on life expectancy, functional status, anatomy of the arterial occlusive disease, and surgical risk. For patients with aortoiliac disease, endovascular therapy has become first-line therapy for all but the most severe patterns of occlusion, and aortofemoral bypass surgery is a highly effective and durable treatment for the latter group. For infrainguinal disease, the available data suggest that surgical bypass with vein is the preferred therapy for CLI patients likely to survive 2 years or more, and for those with long segment occlusions or severe infrapopliteal disease who have an acceptable surgical risk. Endovascular therapy may be preferred in patients with reduced life expectancy, those who lack usable vein for bypass or who are at elevated risk for operation, and those with less severe arterial occlusions. Patients with unreconstructable disease, extensive necrosis involving weight-bearing areas, nonambulatory status, or other severe comorbidities may be considered for primary amputation or palliative measures

Athletic pubalgia (sports hernia)

Athletic pubalgia or sports hernia is a syndrome of chronic lower abdomen and groin pain that may occur in athletes and nonathletes. Because the differential diagnosis of chronic lower abdomen and groin pain is so broad, only a small number of patients with chronic lower abdomen and groin pain fulfill the diagnostic criteria of athletic pubalgia (sports hernia). The literature published to date regarding the cause, pathogenesis, diagnosis, and treatment of sports hernias is confusing. This article summarizes the current information and our present approach to this chronic lower abdomen and groin pain syndrome

Translational reprogramming as a driver of antimony-drug resistance in Leishmania

Abstract Leishmania is a unicellular protozoan that has a limited transcriptional control and mostly uses post-transcriptional regulation of gene expression, although the molecular mechanisms of the process are still poorly understood. Treatments of leishmaniasis, pathologies associated with Leishmania infections, are limited due to drug resistance. Here, we report dramatic differences in mRNA translation in antimony drug-resistant and sensitive strains at the full translatome level. The major differences (2431 differentially translated transcripts) were demonstrated in the absence of the drug pressure supporting that complex preemptive adaptations are needed to efficiently compensate for the loss of biological fitness once they are exposed to the antimony. In contrast, drug-resistant parasites exposed to antimony activated a highly selective translation of only 156 transcripts. This selective mRNA translation is associated with surface protein rearrangement, optimized energy metabolism, amastins upregulation, and improved antioxidant response. We propose a novel model that establishes translational control as a major driver of antimony-resistant phenotypes in Leishmania

Use of cholecystostomy tubes in the management of patients with primary diagnosis of acute cholecystitis

BACKGROUND: Management of patients with severe acute cholecystitis (AC) remains controversial. In settings where laparoscopic cholecystectomy (LC) can be technically challenging or medical risks are exceedingly high, surgeons can choose between different options, including LC conversion to open cholecystectomy or surgical cholecystostomy tube (CCT) placement, or initial percutaneous CCT. We reviewed our experience treating complicated AC with CCT at a tertiary-care academic medical center. STUDY DESIGN: All adult patients (n = 185) admitted with a primary diagnosis of AC and who received CCT from 2002 to 2010 were identified retrospectively through billing and diagnosis codes. RESULTS: Mean patient age was 71 years and 80% had \u3e/=1 comorbidity (mean 2.6). Seventy-eight percent of CCTs were percutaneous CCT placement and 22% were surgical CCT placement. Median length of stay from CCT insertion to discharge was 4 days. The majority (57%) of patients eventually underwent cholecystectomy performed by 20 different surgeons in a median of 63 days post-CCT (range 3 to 1,055 days); of these, 86% underwent LC and 13% underwent open conversion or open cholecystectomy. In the radiology and surgical group, 50% and 80% underwent subsequent cholecystectomy, respectively, at a median of 63 and 60 days post-CCT. Whether surgical or percutaneous CCT placement, approximately the same proportion of patients (85% to 86%) underwent LC as definitive treatment. CONCLUSIONS: This 9-year experience shows that use of CCT in complicated AC can be a desirable alternative to open cholecystectomy that allows most patients to subsequently undergo LC. Additional studies are underway to determine the differences in cost, training paradigms, and quality of life in this increasingly high-risk surgical population. rights reserved