Advanced limb salvage: Pedal artery interventions.

Chronic limb-threatening ischemia (CLTI) is on the rise due to the increasing prevalence of diabetes, which is a significant cause of morbidity and mortality worldwide. Due to diabetes, many patients with CLTI present with a predominance of tibial and pedal artery disease. Despite best care, limb amputation cannot always be prevented. Surgical bypass has always been the mainstay in distal revascularization and limb salvage; however, many patients with CLTI have comorbidities, insufficient vein, and anatomic abnormalities that prevent them from undergoing surgery. As a result, endovascular therapies have increased over the last 2 decades and are providing revascularization options in these patients. Although most of the current endovascular literature has focused on above-ankle arterial interventions, recent studies have highlighted the feasibility, safety, and clinical importance of pedal artery interventions. These endovascular techniques hold promise in relieving ischemic pain, healing foot ulcers, reducing rates and extent of amputation, and improving patient functionality and quality of life. This review aims to comprehensively detail pedal artery interventions in terms of anatomy, technique, intraprocedural imaging, and outcomes. In addition, suggestions of when to perform pedal artery interventions and post-intervention surveillance options will be discussed.

Population-Based Health Utility Assessment of Migraine Headache Symptoms before and after Surgical Intervention.

BACKGROUND: Approximately 30 million Americans suffer from migraine headaches. The primary goals of this study are to (1) use Migraine-Specific Symptoms and Disability criteria and Migraine Headache Index to describe the symptomatic improvement following decompressive surgery for refractory migraines, and (2) use the average Migraine Headache Index preoperatively and postoperatively for health utility assessment from a healthy patient's perspective. METHODS: The Migraine-Specific Symptoms and Disability criteria and the Migraine Headache Index were used to characterize migraine symptoms in the authors' patient population before and after decompressive surgery. Healthy individuals were randomized to a scenario in which they assumed either the preoperative or postoperative average patient symptom profile described by the authors' migraine patients. Health utility assessments were used to quantify the evaluation of health states the authors' patients experienced before and after surgical migraine therapy. RESULTS: Twenty-five patients underwent surgery for migraine headaches. The Migraine-Specific Symptoms and Disability questionnaire showed a significant decrease in both frequency of headaches per month (p < 0.0001) and overall pain score (p = 0.007). The Migraine Headache Index demonstrated a statistically significant improvement (p = 0.03). Healthy individuals in the preoperative group had significantly lower utility scores compared with the postoperative group in all of the health utility assessments completed for migraine symptoms. CONCLUSION: This is the first study to use health utility assessments to attest the efficacy of decompressive therapy by demonstrating the population perspective, which perceived a significant improvement in quality of life following the surgical treatment of migraines in the authors' patients. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

A role for glycolipid biosynthesis in severe fever with thrombocytopenia syndrome virus entry.

A novel bunyavirus was recently found to cause severe febrile illness with high mortality in agricultural regions of China, Japan, and South Korea. This virus, named severe fever with thrombocytopenia syndrome virus (SFTSV), represents a new group within the Phlebovirus genus of the Bunyaviridae. Little is known about the viral entry requirements beyond showing dependence on dynamin and endosomal acidification. A haploid forward genetic screen was performed to identify host cell requirements for SFTSV entry. The screen identified dependence on glucosylceramide synthase (ugcg), the enzyme responsible for initiating de novo glycosphingolipid biosynthesis. Genetic and pharmacological approaches confirmed that UGCG expression and enzymatic activity were required for efficient SFTSV entry. Furthermore, inhibition of UGCG affected a post-internalization stage of SFTSV entry, leading to the accumulation of virus particles in enlarged cytoplasmic structures, suggesting impaired trafficking and/or fusion of viral and host membranes. These findings specify a role for glucosylceramide in SFTSV entry and provide a novel target for antiviral therapies.

The major cellular sterol regulatory pathway is required for Andes virus infection.

The Bunyaviridae comprise a large family of RNA viruses with worldwide distribution and includes the pathogenic New World hantavirus, Andes virus (ANDV). Host factors needed for hantavirus entry remain largely enigmatic and therapeutics are unavailable. To identify cellular requirements for ANDV infection, we performed two parallel genetic screens. Analysis of a large library of insertionally mutagenized human haploid cells and a siRNA genomic screen converged on components (SREBP-2, SCAP, S1P and S2P) of the sterol regulatory pathway as critically important for infection by ANDV. The significance of this pathway was confirmed using functionally deficient cells, TALEN-mediated gene disruption, RNA interference and pharmacologic inhibition. Disruption of sterol regulatory complex function impaired ANDV internalization without affecting virus binding. Pharmacologic manipulation of cholesterol levels demonstrated that ANDV entry is sensitive to changes in cellular cholesterol and raises the possibility that clinically approved regulators of sterol synthesis may prove useful for combating ANDV infection.

Expression of the chitinase family glycoprotein YKL-40 in undifferentiated, differentiated and trans-differentiated mesenchymal stem cells.

The glycoprotein YKL-40 (CHI3L1) is a secreted chitinase family protein that induces angiogenesis, cell survival, and cell proliferation, and plays roles in tissue remodeling and immune regulation. It is expressed primarily in cells of mesenchymal origin, is overexpressed in numerous aggressive carcinomas and sarcomas, but is rarely expressed in normal ectodermal tissues. Bone marrow-derived mesenchymal stem cells (MSCs) can be induced to differentiate into various mesenchymal tissues and trans-differentiate into some non-mesenchymal cell types. Since YKL-40 has been used as a mesenchymal marker, we followed YKL-40 expression as undifferentiated MSCs were induced to differentiate into bone, cartilage, and neural phenotypes. Undifferentiated MSCs contain significant levels of YKL-40 mRNA but do not synthesize detectable levels of YKL-40 protein. MSCs induced to differentiate into chondrocytes and osteocytes soon began to express and secrete YKL-40 protein, as do ex vivo cultured chondrocytes and primary osteocytes. In contrast, MSCs induced to trans-differentiate into neurons did not synthesize YKL-40 protein, consistent with the general absence of YKL-40 protein in normal CNS parenchyma. However, these trans-differentiated neurons retained significant levels of YKL-40 mRNA, suggesting the mechanisms which prevented YKL-40 translation in undifferentiated MSCs remained in place, and that these trans-differentiated neurons differ in at least this way from neurons derived from neuronal stem cells. Utilization of a differentiation protocol containing ß-mercaptoethanol resulted in cells that expressed significant amounts of intracellular YKL-40 protein that was not secreted, which is not seen in normal cells. Thus the synthesis of YKL-40 protein is a marker for MSC differentiation into mature mesenchymal phenotypes, and the presence of untranslated YKL-40 mRNA in non-mesenchymal cells derived from MSCs reflects differences between differentiated and trans-differentiated phenotypes.

The secretion ATPase ComGA is required for the binding and transport of transforming DNA.

Transformation requires specialized proteins to facilitate the binding and uptake of DNA. The genes of the Bacillus subtilis comG operon (comGA-G) are required for transformation and to assemble a structure, the pseudopilus, in the cell envelope. No role for the pseudopilus has been established and the functions of the individual comG genes are unknown. We show that among the comG genes, only comGA is absolutely required for DNA binding to the cell surface. ComEA, an integral membrane DNA-binding protein plays a minor role in the initial binding step, while an unidentified protein which communicates with ComGA must be directly responsible for binding to the cell. We show that the use of resistance to DNase to measure 'DNA uptake' reflects the movement of transforming DNA to a protected state in which it is not irreversibly associated with the protoplast, and presumably resides outside the cell membrane, in the periplasm or associated with the cell wall. We suggest that ComGA is needed for the acquisition of DNase resistance as well as for the binding of DNA to the cell surface. Finally, we show that the pseudopilus is required for DNA uptake and we offer a revised model for the transformation process.

Maf acts downstream of ComGA to arrest cell division in competent cells of B. subtilis.

Transformable (competent) cells of Bacillus subtilis are blocked in cell division because the traffic ATPase ComGA prevents the formation of FtsZ rings. Although ComGA-deficient cells elongate and form FtsZ rings, cell division remains blocked at a later stage and the cells become mildly filamented. Here we show that the highly conserved protein Maf is synthesized predominantly in competent cells under the direct control of the transcription factor ComK and is solely responsible for the later block in cell division. In vivo and in vitro data show that Maf binds to both ComGA and DivIVA. A point mutation in maf that interferes with Maf binding to DivIVA also interferes with the ability of Maf to inhibit cell division. Based on these findings, we propose that Maf and ComGA mediate mechanisms for the inhibition of cell division in competent cells with Maf acting downstream of ComGA. We further suggest that Maf must interact with DivIVA to inhibit cell division.

McsA and B mediate the delocalization of competence proteins from the cell poles of Bacillus subtilis.

During the development of transformability (competence), Bacillus subtilis synthesizes a set of proteins that mediate both the uptake of DNA at the cell poles and the recombination of this DNA with the resident chromosome. Most, if not all, of these Com proteins localize to the poles of the cell, where they associate with one another, and are then seen to delocalize as transformability declines. In this study, we use fluorescence microscopy to analyse the localization and delocalization processes. We show that localization most likely occurs by a diffusion-capture mechanism, not requiring metabolic energy, whereas delocalization is prevented in the presence of sodium azide. The kinetics of localization suggest that this process requires the synthesis of a critical protein or set of proteins, which are needed to anchor the Com protein complex to the poles. We further show that the protein kinase proteins McsA and McsB are needed for delocalization, as are ClpP and either of the AAA(+) (ATPases associated with a variety of cellular activities) proteins ClpC or ClpE. Of these proteins, at least McsB, ClpC and ClpP localize to the cell poles of competent cells. Our evidence strongly suggests that delocalization depends on the degradation of the postulated anchor protein(s) by the McsA-McsB-(ClpC or ClpE)-ClpP protease in an ATP-dependent process that involves the autophosphorylation of McsB. The extent of cell-pole association at any given time reflects the relative rates of localization and delocalization. The kinetics of this dynamic process differs for individual Com proteins, with the DNA-binding proteins SsbB and DprA exhibiting less net localization.