Rescue Approach Research Articles

Diabetic foot management: multidisciplinary approach for advanced lesion rescue.

The diabetic foot is a complication of diabetes affecting 15% of diabetics in their lives. It is associated to diabetic neuropathy and peripheral vascular disease and its incidence has increased. The ulceration is the initial cause of a dramatic process leading, if not correctly treated, to amputations. Both neuropathy, neuro-ischemia and infections have a role in determining healing or worsening of the lesions and 85% of all amputations in diabetic patients are preceded by a foot ulceration deteriorating to a severe gangrene or infection. The different causative agents and the different clinical presentations of diabetic foot ask a multidisciplinary approach in order to address treatments to the final goals, the prevention of the amputations and the maintenance of a functional foot able with weight-bearing ability. Many professional figures, diabetologists, surgeons (both general and vascular and orthopedics), interventional radiologists, infectious diseases specialists, specialized nurses, podiatrists, orthotic technicians, are called to apply their knowledges to the diabetic patients affected by diabetic foot in a virtuous circle leading to reach the goals, with the imperative action of the multidisciplinary team. The so organized center will allow both a correct and rapid diagnosis, the use in ambulatorial environments of modern tools, or the hospitalization in multitasking wards, in which all the complications and the necessary treatments are possible, both in emergencies or in elective way, considering both revascularizations and surgery.

Analysis of Cellular Tyrosine Phosphorylation via Chemical Rescue of Conditionally Active Abl Kinase.

Identifying direct substrates targeted by protein kinases is important in understanding cellular physiology and intracellular signal transduction. Mass spectrometry-based quantitative proteomics provides a powerful tool for comprehensively characterizing the downstream substrates of protein kinases. This approach is efficiently applied to receptor kinases that can be precisely, directly, and rapidly activated by some agent, such as a growth factor. However, nonreceptor tyrosine kinase Abl lacks the experimental advantage of extracellular growth factors as immediate and direct stimuli. To circumvent this limitation, we combine a chemical rescue approach with quantitative phosphoproteomics to identify targets of Abl and their phosphorylation sites with enhanced temporal resolution. Both known and novel putative substrates are identified, presenting opportunities for studying unanticipated functions of Abl under physiological and pathological conditions.

The Study on Aircraft Search and Rescue Technology for Nuclear Power Plant Accident based on C4ISRE Integrating Ant Colony Algorithm

When the nuclear emergency accident occurs, it was very important to search and rescue survivors scientifically and reasonably. So, taking the Hongyanhe Nuclear Power Plant for example, based on C4ISRE, the optimize path for search and rescue was deduced successfully. Experiments showed that the optimize path was 1→2→3→5→4→7→13→15→12→11→9→14→10→8→6→1 and the shortest path length was 4607.6854 m. Evacuation times for adult, child and old man were about 80s, 145s, and 192s respectively in the area (number 1); Evacuation time for adult, child and old man were about 40s, 72s and 96s respectively in the area (number 2); Evacuation time for adult, child and old man were about 95s, 172s and 228s respectively in the area (number 3); Evacuation time for adult, child and old man were about 143s, 260s and 345s respectively in the area (number 4); Evacuation time for adult, child and old man were about 20s, 36s and 48s respectively in the area (number 5); Evacuation time for adult, child and old man were about 20s, 36s and 60s respectively in the area (number 6). About the area 4, it was the most time-consuming area for child and old man evacuation, so professional rescue staff (such as special police or special forces) and special vehicles should be deployed in this area in order to ensure effective evacuation for child and old man. C4ISRE provided a new and effective technical approach for emergency rescue of nuclear accident which could enhance nuclear emergency preparedness response capabilities and organizational efficiency.

Control of growth and gut maturation by HoxD genes and the associated lncRNA Haglr

During embryonic development, Hox genes participate in the building of a functional digestive system in metazoans, and genetic conditions involving these genes lead to important, sometimes lethal, growth retardation. Recently, this phenotype was obtained after deletion of Haglr, the Hoxd antisense growth-associated long noncoding RNA (lncRNA) located between Hoxd1 and Hoxd3 In this study, we have analyzed the function of Hoxd genes in delayed growth trajectories by looking at several nested targeted deficiencies of the mouse HoxD cluster. Mutant pups were severely stunted during the suckling period, but many recovered after weaning. After comparing seven distinct HoxD alleles, including CRISPR/Cas9 deletions involving Haglr, we identified Hoxd3 as the critical component for the gut to maintain milk-digestive competence. This essential function could be abrogated by the dominant-negative effect of HOXD10 as shown by a genetic rescue approach, thus further illustrating the importance of posterior prevalence in Hox gene function. A role for the lncRNA Haglr in the control of postnatal growth could not be corroborated.

Positional cloning of quantitative trait nucleotides for blood pressure and cardiac QT-interval by targeted CRISPR/Cas9 editing of a novel long non-coding RNA.

Multiple GWAS studies have reported strong association of cardiac QT-interval to a region on HSA17. Interestingly, a rat locus homologous to this region is also linked to QT-intervals. The high resolution positional mapping study located the rat QT-interval locus to a <42.5kb region on RNO10. This region contained no variants in protein-coding sequences, but a prominent contiguous 19bp indel polymorphism was noted within a novel predicted long non-coding RNA (lncRNA), which we named as Rffl-lnc1. To assess the candidacy of this novel lncRNA on QT-interval, targeted CRISPR/Cas9 based genome-engineering approaches were applied on the rat strains used to map this locus. Targeted disruption of the rat Rffl-lnc1 locus caused aberrant, short QT-intervals and elevated blood pressure. Further, to specifically examine the significance of the 19bp polymorphism within the Rffl-lnc1 locus, a CRISPR/Cas9 based targeted knock-in rescue model was constructed by inserting the 19bp into the strain which contained the deletion polymorphism. The knock-in alleles successfully rescued the aberrant QT-interval and blood pressure phenotypes. Further studies revealed that the 19bp polymorphism was necessary and sufficient to recapitulate the phenotypic effect of the previously mapped <42.5kb rat locus. To our knowledge, this study is the first demonstration of a combination of both CRISPR/Cas9 based targeted disruption as well as CRISPR/Cas9 based targeted knock-in rescue approaches applied for a mammalian positional cloning study, which defines the quantitative trait nucleotides (QTNs) within a rat long non-coding RNA as being important for the pleiotropic regulation of both cardiac QT-intervals and blood pressure.

Genetic rescue of an endangered domestic animal through outcrossing with closely related breeds: A case study of the Norwegian Lundehund.

Genetic rescue, outcrossing with individuals from a related population, is used to augment genetic diversity in populations threatened by severe inbreeding and extinction. The endangered Norwegian Lundehund dog underwent at least two severe bottlenecks in the 1940s and 1960s that each left only five inbred dogs, and the approximately 1500 dogs remaining world-wide today appear to descend from only two individuals. The Lundehund has a high prevalence of a gastrointestinal disease, to which all remaining dogs may be predisposed. Outcrossing is currently performed with three Nordic Spitz breeds: Norwegian Buhund, Icelandic Sheepdog, and Norrbottenspets. Examination of single nucleotide polymorphism (SNP) genotypes based on 165K loci in 48 dogs from the four breeds revealed substantially lower genetic diversity for the Lundehund (HE 0.035) than for other breeds (HE 0.209–0.284). Analyses of genetic structure with > 15K linkage disequilibrium-pruned SNPs showed four distinct genetic clusters. Pairwise FST values between Lundehund and the candidate breeds were highest for Icelandic Sheepdog, followed by Buhund and Norrbottenspets. We assessed the presence of outlier loci among candidate breeds and examined flanking genome regions (1 megabase) for genes under possible selection to identify potential adaptive differences among breeds; outliers were observed in flanking regions of genes associated with key functions including the immune system, metabolism, cognition and physical development. We suggest crossbreeding with multiple breeds as the best strategy to increase genetic diversity for the Lundehund and to reduce the incidence of health problems. For this project, the three candidate breeds were first selected based on phenotypes and then subjected to genetic investigation. Because phenotypes are often paramount for domestic breed owners, such a strategy could provide a helpful approach for genetic rescue and restoration of other domestic populations at risk, by ensuring the involvement of owners, breeders and managers at the start of the project.

Overstating Moral Hazard: Lessons from Two Decades of Banking Crises

Over the past two decades a variety of banking system rescue approaches have been used, including in the 1997 Asian financial crisis, the 2008 global financial crisis, and the 2010 European debt crisis. By analysing the resolution of these crises as well as the approach to addressing bad loans in the People’s Republic of China, this paper provides a new perspective on the common belief that bailouts are invariably harmful to public funds or excessively conducive to moral hazard. Depending on the form of bailout, bank restructuring, and fiscal backstop, resolutions can be an effective means to restore a banking system. This paper argues that in a systemic financial crisis, a combination of balance sheet restructuring and the use of asset management companies to deal with non-performing loans is often the best choice. However, a fully-fledged resolution that triggers the bail-in procedure remains the best approach for non-systemically important financial institution failures which take place outside of systemic crises, namely when the failure is idiosyncratic.

A Can’t Ventilate, Can’t Intubate Scenario in a Remote Location: A Case Report of a Rescue Approach

Background and objectives: The number of procedures in remote locations has dramatically increased, being an anaesthetic challenge. The most common complications are respiratory events often by over sedation. In remote locations, a can´t ventilate can’t intubate scenario is worrisome. Case report: We present a patient scheduled for percutaneous endoscopic gastrostomy under monitored anaesthesia care who represented a “can´t ventilate, can’t intubate” scenario in the Gastroenterology Department and a rescue approach used to maintain patient oxygenation. The authors were the emergency anaesthesia team in the emergency department. The patient recovered with no sequelae. Conclusions: The case highlights the importance of planning difficult airway management, delineating alternative plans, and knowing in advance the equipment available. A careful evaluation of the airway remains a cornerstone in anesthesia, even providing monitored anesthesia care. The paper draws attention to aspects that could be improved in the approach of a similar case that could happen again in this clinical context.

Pharmacological Chaperones as Potential Therapeutic Strategies for Misfolded Mutant Vasopressin Receptors.

Pharmacological chaperones recently opened new possibilities in G protein-coupled receptor drug discovery. Even more interestingly, some unique ligands combine pharmacological chaperoning and biased agonism properties, boosting their therapeutic interest in many human diseases resulting from G protein-coupled receptor mutation and misfolding. These compounds displaying dual characteristics would constitute a perfect treatment for congenital Nephrogenic Diabetes Insipidus, a typical conformational disease. This X-linked genetic pathology is mostly associated with inactivating mutations of the renal arginine-vasopressin V2 receptor leading to misfolding and intracellular retention of the receptor, causing the inability of patients to concentrate their urine in response to the antidiuretic hormone. Cell-permeable pharmacological chaperones have been successfully challenged to restore plasma membrane localization of many V2 receptor mutants. In addition, different classes of specific ligands such as antagonists, agonists as well as biased agonists of the V2 receptor have proven their usefulness in rescuing mutant receptor function. This is particularly relevant for small-molecule biased agonists which only trigger Gs protein activation and cyclic adenosine monophosphate production, the V2-induced signaling pathway responsible for water reabsorption. In parallel, high-throughput screening assays based on receptor trafficking rescue approaches have been developed to discover novel V2 pharmacological chaperone molecules from different chemical libraries. These new hit compounds, which still need to be pharmacologically characterized and functionally tested in vivo, represent promising candidates for the treatment of congenital Nephrogenic Diabetes Insipidus.

Biological characterization of chemically diverse compounds targeting the Plasmodium falciparum coenzyme A synthesis pathway.

BackgroundIn the fight against malaria, the discovery of chemical compounds with a novel mode of action and/or chemistry distinct from currently used drugs is vital to counteract the parasite’s known ability to develop drug resistance. Another desirable aspect is efficacy against gametocytes, the sexual developmental stage of the parasite which enables the transmission through Anopheles vectors. Using a chemical rescue approach, we previously identified compounds targeting Plasmodium falciparum coenzyme A (CoA) synthesis or utilization, a promising target that has not yet been exploited in anti-malarial drug development.ResultsWe report on the outcomes of a series of biological tests that help to define the species- and stage-specificity, as well as the potential targets of these chemically diverse compounds. Compound activity against P. falciparum gametocytes was determined to assess stage-specificity and transmission-reducing potential. Against early stage gametocytes IC50 values ranging between 60 nM and 7.5 μM were obtained. With the exception of two compounds with sub-micromolar potencies across all intra-erythrocytic stages, activity against late stage gametocytes was lower. None of the compounds were specific pantothenate kinase inhibitors. Chemical rescue profiling with CoA pathway intermediates demonstrated that most compounds acted on either of the two final P. falciparum CoA synthesis enzymes, phosphopantetheine adenylyltransferase (PPAT) or dephospho CoA kinase (DPCK). The most active compound targeted either phosphopantothenoylcysteine synthetase (PPCS) or phosphopantothenoylcysteine decarboxylase (PPCDC). Species-specificity was evaluated against Trypanosoma cruzi and Trypanosoma brucei brucei. No specific activity against T. cruzi amastigotes was observed; however three compounds inhibited the viability of trypomastigotes with sub-micromolar potencies and were confirmed to act on T. b. brucei CoA synthesis. ConclusionsUtilizing the compounds we previously identified as effective against asexual P. falciparum, we demonstrate for the first time that gametocytes, like the asexual stages, depend on CoA, with two compounds exhibiting sub-micromolar potencies across asexual forms and all gametocytes stages tested. Furthermore, three compounds inhibited the viability of T. cruzi and T. b. brucei trypomastigotes with sub-micromolar potencies and were confirmed to act on T. b. brucei CoA synthesis, indicating that the CoA synthesis pathway might represent a valuable new drug target in these parasite species.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1860-3) contains supplementary material, which is available to authorized users.

Long-Term Outcomes of External Repair as a Rescue Operation for Atrioventricular Groove Disruption

Atrioventricular groove disruption (AVGD) is an uncommon but lethal complication of mitral valve operations associated with mortality approaching 90%. Traditionally, an "internal" repair is performed requiring prosthesis explantation, complete atrioventricular groove reconstruction using a patch positioned from within the cardiac cavity, and subsequent prosthesis reimplantation. This is a massive undertaking that is usually unsuccessful. We examine the utility of an alternative, "external" approach for rescue of AVGD. A retrospective review was conducted of consecutive patients with AVGD after mitral operations at 3 North American medical centers. All patients underwent external repair as a rescue procedure. The external repair technique was conducted on cardiopulmonary bypass using direct suturing or felt-reinforced suturing, or both, of the atrioventricular groove. This was supplemented as needed with applications of BioGlue (CryoLife, Kennesaw, GA), external bovine pericardial patch, left atrial buttress, and coronary bypass grafting of the circumflex circulation. Between 1995 and 2015, 3,071 mitral valve operations resulted in 13 AVGDs (incidence, 0.42%). Average patient age was 75.2 years (range, 59-90 years), and 77% (10 of 13) were women. The 30-day mortality was 15.4% (2 of 13), and hospital mortality was 23.1% (3 of 13). Survival rates at 1, 3, and 5 years were 72.7%, 72.7%, and 44.4%, respectively. Seven patients are currently still alive and remain in no greater than New York Heart Association Functional Classification II. A stable pseudoaneurysm subsequently developed in 2 patients. The incidence of AVGD after mitral operations is low. Despite an older population with more tissue fragility, the external approach represents an effective, alternative repair technique for rescue of AVGD with encouraging results.

Plasmids for variable expression of proteins targeted to the mitochondrial matrix or intermembrane space.

We describe the construction and uses of a series of plasmids for directing expression to varied levels of exogenous proteins targeted to the mitochondrial matrix or intermembrane space. We found that the level of protein expression achieved, the kinetics of expression and mitochondrial import, and half-life after import can each vary with the protein examined. These factors should be considered when directing localization of an exogenous protein to mitochondria for rescue, proteomics, or other approaches. We describe the construction of a collection of plasmids for varied expression of proteins targeted to the mitochondrial matrix or intermembrane space, using previously defined targeting sequences and strength CMV promoters. The limited size of these compartments makes them particularly vulnerable to artifacts from over-expression. We found that different proteins display different kinetics of expression and import that should be considered when analyzing results from this approach. Finally, this collection of plasmids has been deposited in the Addgene plasmid repository to facilitate the ready access and use of these tools.

Plerixafor as preemptive strategy results in high success rates in autologous stem cell mobilization failure.

Plerixafor in combination with granulocyte-colony stimulating factor (G-CSF) is approved for autologous stem cell mobilization in poor mobilizing patients with multiple myeloma or malignant lymphoma. The purpose of this study was to evaluate efficacy and safety of plerixafor in an immediate rescue approach, administrated subsequently to G-CSF alone or chemotherapy and G-CSF in patients at risk for mobilization failure. Eighty-five patients mobilized with G-CSF alone or chemotherapy were included. Primary endpoint was the efficacy of the immediate rescue approach of plerixafor to achieve ≥2.0 × 106 CD34+ cells/kg for a single or ≥5 × 106 CD34+ cells/kg for a double transplantation and potential differences between G-CSF and chemotherapy-based mobilization. Secondary objectives included comparison of stem cell graft composition including CD34+ cell and lymphocyte subsets with regard to the mobilization regimen applied. No significant adverse events were recorded. A median 3.9-fold increase in CD34+ cells following plerixafor was observed, resulting in 97% patients achieving at least ≥2 × 106 CD34+ cells/kg. Significantly more differentiated granulocyte and monocyte forming myeloid progenitors were collected after chemomobilization whereas more CD19+ and natural killer cells were collected after G-CSF. Fifty-two patients underwent transplantation showing rapid and durable engraftment, irrespectively of the stem cell mobilization regimen used. The addition of plerixafor in an immediate rescue model is efficient and safe after both, G-CSF and chemomobilization and results in extremely high success rates. Whether the differences in graft composition have a clinical impact on engraftment kinetics, immunologic recovery, and graft durability have to be analysed in larger prospective studies.

OR44 Assessing the dynamics between two cord blood units in adult double cord transplantation

A marked % of patients receiving double cord blood transplantation (DCBT) demonstrate a single blood cord unit (CBU) emerging as the “winner” to sustain long-term hematopoiesis. We sought to gain a better understanding of the kinetics of double CBU engraftment shortly after transplant (txp) and predict engraftment in peripheral blood rather than bone marrow aspirate using a novel and more sensitive method of quantitative PCR (qPCR) compared to short tandem repeat. 30 consecutive patients (>18 years old) were enrolled undergoing DCBT, myeloablative conditioning and both CBUs ⩾4/6 HLA-matched. qPCR (AllelSEQR® chimerism assay) was used to evaluate % of donor or recipient DNA (accuracy ±0.1%). Peripheral blood samples were collected on days 3, 7, 14, and 21. DNA was amplified by whole genome amplification prior to chimerism analysis. DNA from the recipient was still detected in the circulation for an average of 7 days. While not originally expected, this is not surprising since it takes time for the recipient cells/DNA to clear the blood stream after pre-txp conditioning. As for the two CBUs, in the vast majority of the cases, an increase in DNA for both CBUs was detected up to day 7, albeit to different degrees. In many cases it was possible to determine which of the cords will win by day 7. Examples of the opposite are in Figs. B1-3.Download : Download high-res image (230KB)Download : Download full-size image Engraftment of CBUs takes a significant amount of time. Normally, clinicians are not sure if the txp was successful until days 21–28, potentially leaving the patient at risk of non-engraftment and no time for a rescue approach. These results are the first real glimpse into what is occurring this early post-txp and can reassure the start of engraftment. In addition, we have shown that there is an interplay between the two cords in which both seem to proliferate initially but eventually one takes over. A larger cohort of patients should be analyzed to increase our understanding of the cords interplay and identify characteristics that may help predict which cord is more likely to engraft.

Evaluation of in vivo bioactivities of recombinant hypo- (FSH21/18) and fully- (FSH24) glycosylated human FSH glycoforms in Fshb null mice

The hormone - specific FSHβ subunit of the human FSH heterodimer consists of N-linked glycans at Asn7 and Asn24 residues that are co-translationally attached early during subunit biosynthesis. Differences in the number of N-glycans (none, one or two) on the human FSHβ subunit contribute to macroheterogeneity in the FSH heterodimer. The resulting FSH glycoforms are termed hypo-glycosylated (FSH21/18, missing either an Asn24 or Asn7 N-glycan chain on the β - subunit, respectively) or fully glycosylated (FSH24, possessing of both Asn7 and Asn24 N-linked glycans on the β - subunit) FSH. The recombinant versions of human FSH glycoforms (FSH21/18 and FSH24) have been purified and biochemically characterized. In vitro functional studies have indicated that FSH21/18 exhibits faster FSH- receptor binding kinetics and is much more active than FSH24 in every assay tested to date. However, the in vivo bioactivity of the hypo-glycosylated FSH glycoform has never been tested. Here, we evaluated the in vivo bioactivities of FSH glycoforms in Fshb null mice using a pharmacological rescue approach. In Fshb null female mice, both hypo- and fully-glycosylated FSH elicited an ovarian weight gain response by 48 h and induced ovarian genes in a dose- and time-dependent manner. Quantification by real time qPCR assays indicated that hypo-glycosylated FSH21/18 was bioactive in vivo and induced FSH-responsive ovarian genes similar to fully-glycosylated FSH24. Western blot analyses followed by densitometry of key signaling components downstream of the FSH-receptor confirmed that the hypo-glycosylated FSH21/18 elicited a response similar to that by fully-glycosylated FSH24 in ovaries of Fshb null mice. When injected into Fshb null males, hypo-glycosylated FSH21/18 was more active than the fully-glycosylated FSH24 in inducing FSH-responsive genes and Sertoli cell proliferation. Thus, our data establish that recombinant hypo-glycosylated human FSH21/18 glycoform elicits bioactivity in vivo similar to the fully-glycosylated FSH. Our studies may have clinical implications particularly in formulating FSH-based ovarian follicle induction protocols using a combination of different human FSH glycoforms.

HCN-channel dendritic targeting requires bipartite interaction with TRIP8b and regulates antidepressant-like behavioral effects.

Major Depressive Disorder is a prevalent psychiatric condition with limited therapeutic options beyond monoaminergic therapies. Although effective in some individuals, many patients fail to respond adequately to existing treatments and new pharmacologic targets are needed. HCN channels regulate excitability in neurons and blocking HCN channel function has been proposed as a novel antidepressant strategy. However, systemic blockade of HCN channels produces cardiac effects that limit this approach. Knockout (KO) of the brain-specific HCN channel auxiliary subunit TRIP8b also produces antidepressant-like behavioral effects and suggests that inhibiting TRIP8b function could produce antidepressant-like effects without affecting the heart. We examined the structural basis of TRIP8b-mediated HCN channel trafficking and its relationship to antidepressant-like behavior using a viral rescue approach in TRIP8b KO mice. We found that restoring TRIP8b to the hippocampus was sufficient to reverse the impaired HCN channel trafficking and antidepressant-like behavioral effects caused by TRIP8b KO. Moreover, we found that hippocampal expression of a mutated version of TRIP8b further impaired HCN channel trafficking and increased the antidepressant-like behavioral phenotype of TRIP8b KO mice. Thus, modulating the TRIP8b-HCN interaction bidirectionally influences channel trafficking and antidepressant-like behavior. Overall, our work suggests that small molecule inhibitors of the interaction between TRIP8b and HCN should produce antidepressant-like behaviors and could represent a new paradigm for the treatment of Major Depressive Disorder.

Two temporal functions of Glass: Ommatidium patterning and photoreceptor differentiation

Much progress has been made in elucidating the molecular networks required for specifying retinal cells, including photoreceptors, but the downstream mechanisms that maintain identity and regulate differentiation remain poorly understood. Here, we report that the transcription factor Glass has a dual role in establishing a functional Drosophila eye. Utilizing conditional rescue approaches, we confirm that persistent defects in ommatidium patterning combined with cell death correlate with the overall disruption of eye morphology in glass mutants. In addition, we reveal that Glass exhibits a separable role in regulating photoreceptor differentiation. In particular, we demonstrate the apparent loss of glass mutant photoreceptors is not only due to cell death but also a failure of the surviving photoreceptors to complete differentiation. Moreover, the late reintroduction of Glass in these developmentally stalled photoreceptors is capable of restoring differentiation in the absence of correct ommatidium patterning. Mechanistically, transcription profiling at the time of differentiation reveals that Glass is necessary for the expression of many genes implicated in differentiation, i.e. rhabdomere morphogenesis, phototransduction, and synaptogenesis. Specifically, we show Glass directly regulates the expression of Pph13, which encodes a transcription factor necessary for opsin expression and rhabdomere morphogenesis. Finally, we demonstrate the ability of Glass to choreograph photoreceptor differentiation is conserved between Drosophila and Tribolium, two holometabolous insects. Altogether, our work identifies a fundamental regulatory mechanism to generate the full complement of cells required for a functional rhabdomeric visual system and provides a critical framework to investigate the basis of differentiation and maintenance of photoreceptor identity.

Endovascular resection of the native aortic valve before transcatheter aortic valve implantation: state of the art and review.

Transcatheter aortic valve implantation was introduced into clinical practice in 2002 as a rescue approach in patients presenting with symptomatic severe aortic stenosis but not eligible for conventional aortic valve replacement. This technique allows implantation of a balloon expandable bioprosthesis without resection of the native aortic valve. Several complications are described as a consequence of the residual highly calcified valve being squeezed against the aortic wall by the stent of the implant. This can result in deformation of the metal stent and paravalvular leakage, risk of occlusion of the coronary ostia, or central and peripheral embolization of valvular debris. To avoid these complications, many authors suggest the possibility to resect and remove the native aortic valve before transcatheter aortic valve implantation. In this field, different authors have described possible techniques and different sources of energy to resect the calcified valve. In this article, we review the development of these experimental techniques and discuss future prospects in this field.

Probing the Catalytic Mechanism of Vibrio harveyi GH20 β-N-Acetylglucosaminidase by Chemical Rescue.

BackgroundVibrio harveyi GH20 β-N-acetylglucosaminidase (VhGlcNAcase) is a chitinolytic enzyme responsible for the successive degradation of chitin fragments to GlcNAc monomers, activating the onset of the chitin catabolic cascade in marine Vibrios.MethodsTwo invariant acidic pairs (Asp303-Asp304 and Asp437-Glu438) of VhGlcNAcase were mutated using a site-directed mutagenesis strategy. The effects of these mutations were examined and the catalytic roles of these active-site residues were elucidated using a chemical rescue approach. Enhancement of the enzymic activity of the VhGlcNAcase mutants was evaluated by a colorimetric assay using pNP-GlcNAc as substrate.ResultsSubstitution of Asp303, Asp304, Asp437 or Glu438 with Ala/Asn/Gln produced a dramatic loss of the GlcNAcase activity. However, the activity of the inactive D437A mutant was recovered in the presence of sodium formate. Our kinetic data suggest that formate ion plays a nucleophilic role by mimicking the β-COO-side chain of Asp437, thereby stabilizing the reaction intermediate during both the glycosylation and the deglycosylation steps.ConclusionsChemical rescue of the inactive D437A mutant of VhGlcNAcase by an added nucleophile helped to identify Asp437 as the catalytic nucleophile/base, and hence its acidic partner Glu438 as the catalytic proton donor/acceptor.General SignificanceIdentification of the catalytic nucleophile of VhGlcNAcases supports the proposal of a substrate-assisted mechanism of GH20 GlcNAcases, requiring the catalytic pair Asp437-Glu438 for catalysis. The results suggest the mechanistic basis of the participation of β-N-acetylglucosaminidase in the chitin catabolic pathway of marine Vibrios.

Simulation for Airway Management in a Critical Care Set Up

The simulators have been used conventionally by pilot training wherein real time scenario and crisis situation is created for management. Similar concept has been recently extended in medical sciences for teaching and training and has found an important role in airway management as well. Simulators are inevitable for learning the technical skills and aids in learning and assessing psychomotor tasks, cognitive and affective skills [1,3,4,7,8]. Simulation practice ensures team dynamics along with application of algorithmic approach for holistic management. Traditionally airway management training was delivered by practicing skills like laryngoscopy, fiberscopic tracheal intubation individually. In real scenario, these individuals’ skills need to be choreographed into an systematic approach. We need to have primary approach for airway management, secondary approach, if it fails and also subsequent rescue approaches. This real time airway management may not be possible in airway trainers by learning individual skills. The algorithms have been proposed by various professional bodes for management of airway [1]. The stimulators would help to acquire the skills and judgment of the equipments and techniques required of the algorithm [1]. The simulators in airway management helps in improving psychomotor level (skill training), cognitive level (decision making) or affective level (interacting with peers/coworkers) [1] The simulators are an important tool for evaluation of efficacy of training and skill retention [1,2,9]. In view of ethical concerns and patient safety, simulator training would become essential prior to interacting with real patients as compared to training on real patients. The simulator available are either partial-task or whole-task trainers or may replicate real time conditions without compromising the patient safety [1]. Though the animal models were initially used for these concerns, but many aspects of real time situations were not feasible in such models [1]. The high-fidelity patient simulation reproduce real-life patient and a similar environment may be created as to be encountered by the learners. Such environment may be considered as sensitizer for the learners for real time stressful situations to handle difficult airway situations in critically ill patient. Unlike real patients, a high-fidelity airway simulator provides various opportunities for different type of airway difficulties and complications. This provides learners an opportunity to perform multiple times under different conditions.