The C-terminal tail of the gp41 transmembrane envelope glycoprotein of HIV-1 clades A, B, C, and D may exist in two conformations: an analysis of sequence, structure, and function

AbstractIn addition to the major ectodomain, the gp41 transmembrane glycoprotein of HIV-1 is now known to have a minor ectodomain that is part of the long C-terminal tail. Both ectodomains are highly antigenic, carry neutralizing and non-neutralizing epitopes, and are involved in virus-mediated fusion activity. However, data have so far been biologically based, and derived solely from T cell line-adapted (TCLA), B clade viruses. Here we have carried out sequence and theoretically based structural analyses of 357 gp41 C-terminal sequences of mainly primary isolates of HIV-1 clades A, B, C, and D. Data show that all these viruses have the potential to form a tail loop structure (the minor ectodomain) supported by three, β-sheet, membrane-spanning domains (MSDs). This means that the first (N-terminal) tyrosine-based sorting signal of the gp41 tail is situated outside the cell membrane and is non-functional, and that gp41 that reaches the cell surface may be recycled back into the cytoplasm through the activity of the second tyrosine-sorting signal. However, we suggest that only a minority of cell-associated gp41 molecules – those destined for incorporation into virions – has 3 MSDs and the minor ectodomain. Most intracellular gp41 has the conventional single MSD, no minor ectodomain, a functional first tyrosine-based sorting signal, and in line with current thinking is degraded intracellularly. The gp41 structural diversity suggested here can be viewed as an evolutionary strategy to minimize HIV-1 envelope glycoprotein expression on the cell surface, and hence possible cytotoxicity and immune attack on the infected cell

Implementation of exon arrays: alternative splicing during T-cell proliferation as determined by whole genome analysis

<p>Abstract</p> <p>Background</p> <p>The contribution of alternative splicing and isoform expression to cellular response is emerging as an area of considerable interest, and the newly developed exon arrays allow for systematic study of these processes. We use this pilot study to report on the feasibility of exon array implementation looking to replace the 3' <it>in vitro </it>transcription expression arrays in our laboratory.</p> <p>One of the most widely studied models of cellular response is T-cell activation from exogenous stimulation. Microarray studies have contributed to our understanding of key pathways activated during T-cell stimulation. We use this system to examine whole genome transcription and alternate exon usage events that are regulated during lymphocyte proliferation in an attempt to evaluate the exon arrays.</p> <p>Results</p> <p>Peripheral blood mononuclear cells form healthy donors were activated using phytohemagglutinin, IL2 and ionomycin and harvested at 5 points over a 7 day period. Flow cytometry measured cell cycle events and the Affymetrix exon array platform was used to identify the gene expression and alternate exon usage changes. Gene expression changes were noted in a total of 2105 transcripts, and alternate exon usage identified in 472 transcript clusters. There was an overlap of 263 transcripts which showed both differential expression and alternate exon usage over time. Gene ontology enrichment analysis showed a broader range of biological changes in biological processes for the differentially expressed genes, which include cell cycle, cell division, cell proliferation, chromosome segregation, cell death, component organization and biogenesis and metabolic process ontologies. The alternate exon usage ontological enrichments are in metabolism and component organization and biogenesis. We focus on alternate exon usage changes in the transcripts of the spliceosome complex. The real-time PCR validation rates were 86% for transcript expression and 71% for alternate exon usage.</p> <p>Conclusions</p> <p>This study illustrates that the Exon array technology has the potential to provide information on both transcript expression and isoform usage, with very little increase in expense.</p

Properties of the C-terminal tail of HIV-1 gp41

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Risk of respiratory failure after repair of thoracoabdominal aortic aneurysms

background: Multiple complications occur after repair of a thoracoabdominal aortic aneurysm, the most common of which is respiratory failure. methods: One hundred consecutive thoracoabdominal aneurysm repairs were studied retrospectively using univariate, bivariate, and multiple logarithmic regression analyses to identify factors associated with respiratory failure. results: The mean of days of intubation was 5.8 ± 0.8 (mean ± SEM), with a median of 2 days. Patients who developed respiratory failure (21%) had a 42% mortality compared with a 6% mortality in patients who did not develop respiratory failure (P <0.001). Statistical analysis demonstrated a significant (P <0.01) age difference between those with respiratory failure (71.9 ± 1.6 years) and those without (65.5 ± 1.3 years). Type II aneurysms occurred in 32% of patients, a 3.2-fold increase in relative risk compared with all other types of aneurysm. Seventy-nine percent of patients had a significant smoking history. Low forced vital capacity and forced expiratory volume were both significant variables in predicting respiratory failure, but neither chronic obstructive pulmonary disease nor emphysema was a predictive variable. Intraoperative blood transfusion (mean 10.5 ± 0.8 units) was associated with respiratory failure (P = 0.05). Postoperative complications associated with respiratory failure were creatinine elevation and pneumonia. conclusion: We conclude that the independent variables affecting respiratory failure after thoracoabdominal aneurysm repair are age, type of aneurysm, excessive intraoperative blood transfusions, creatinine elevation, and postoperative pneumonia

Ischemia-reperfusion injury of the spinal cord: Protective effect of the hydroxyl radical scavenger dimethylthiourea

Purpose: This study was undertaken to evaluate whether neurologic outcome after aortic cross-clamping in rabbits could be improved with perioperative infusion of the hydroxyl radical scavenger dimethylthiourea and, if so, to determine whether it is effective during the period of ischemia, reperfusion, or both. Methods: In 41 New Zealand White rabbits, a snare occlusion device was placed at operation around the infrarenal aorta and tunneled into a subcutaneous position. Animals were then allowed to recover and, 48 hours later, randomized into four groups. In each group, the infrarenal aorta was occluded by tightening the snare in the awake animal. In groups 1, 2, and 3, cross-clamp time was 21 minutes. Group 1 (control) animals received saline solution, whereas group 2 (preclamp 21) received dimethylthiourea 750 mg/kg intravenously just before aortic clamping. In group 3 (prerep 21), dimethylthiourea was given just before reperfusion. Group 4 received dimethylthiourea before clamping, with cross-clamp time extended to 31 minutes. A second dose of saline solution or dimethylthiourea was given 12 hours after clamping in controls and the three treatment groups, respectively. Animals were observed for 5 days, and final neurologic recovery was graded by an independent observer. Animals were then killed, and their spinal cords were removed for histologic examination. Results: Complete paraplegia and marked histologic spinal cord injury at 5 days were seen in 91% ( 10 11) of group 1 (control) animals, whereas all animals in group 2 (preclamp 21) showed neurologic recovery (p < 0.0001). In group 3 (prerep 21), the final paraplegia rate was 50% (5 of 10), in group 4 (preclamp 31), 100% (10 of 10). Conclusions: Our results suggest that hydroxyl radicals play an important role in ischemia-reperfusion injury of the spinal cord and that treatment with dimethylthiourea can prevent paraplegia after 21 minutes of aortic cross-clamping in rabbits

Comparison of operative reconstruction and percutaneous balloon dilatation for central venous obstruction

To evaluate the efficacy of venous reconstruction versus percutaneous transluminal angioplasty for the treatment of obstruction of the superior vena cava and its major tributaries, we retrospectively reviewed the clinical course of 27 patients, of whom 13 underwent operative reconstruction and 15 had angioplasty (1 had both). Three patients had obstruction of the superior vena cava, 8 had occlusion of the innominate veins, and 16 had obstruction of the subclavian or axillary veins. In both treatment groups, mean age, indications, etiology, and location of the lesion were comparable. No major surgical complications occurred; one patient who underwent angioplasty experienced stent migration to the pulmonary artery without sequelae. Primary symptomatic relief at 1 year was achieved in 88% in the surgical group versus 36% in the angioplasty group (

International consensus recommendations for the optimal prioritisation and distribution of surgical services in low-income and middle-income countries: a modified Delphi process

Objectives To develop consensus statements regarding the regional-level or district-level distribution of surgical services in low and middle-income countries (LMICs) and prioritisation of service scale-up.Design This work was conducted using a modified Delphi consensus process. Initial statements were developed by the International Standards and Guidelines for Quality Safe Surgery and Anesthesia Working Group of the Global Alliance for Surgical, Obstetric, Trauma and Anesthesia Care (G4 Alliance) and the International Society of Surgery based on previously published literature and clinical expertise. The Guidance on Conducting and REporting DElphi Studies framework was applied.Setting The Working Group convened in Suva, Fiji for a meeting hosted by the Ministry of Health and Medical Services to develop the initial statements. Local experts were invited to participate. The modified Delphi process was conducted through an electronically administered anonymised survey.Participants Expert LMIC surgeons were nominated for participation in the modified Delphi process based on criteria developed by the Working Group.Primary outcome measures The consensus panel voted on statements regarding the organisation of surgical services, principles for scale-up and prioritisation of scale-up. Statements reached consensus if there was ≥80% agreement among participants.Results Fifty-three nominated experts from 27 LMICs voted on 27 statements in two rounds. Ultimately, 26 statements reached consensus and comprise the current recommendations. The statements covered three major themes: which surgical services should be decentralised or regionalised; how the implementation of these services should be prioritised; and principles to guide LMIC governments and international visiting teams in scaling up safe, accessible and affordable surgical care.Conclusions These recommendations represent the first step towards the development of international guidelines for the scaling up of surgical services in LMICs. They constitute the best available basis for policymaking, planning and allocation of resources for strengthening surgical systems

Care Levels for Fetal Therapy Centers.

Fetal therapies undertaken to improve fetal outcome or to optimize transition to neonate life often entail some level of maternal, fetal, or neonatal risk. A fetal therapy center needs access to resources to carry out such therapies and to manage maternal, fetal, and neonatal complications that might arise, either related to the therapy per se or as part of the underlying fetal or maternal condition. Accordingly, a fetal therapy center requires a dedicated operational infrastructure and necessary resources to allow for appropriate oversight and monitoring of clinical performance and to facilitate multidisciplinary collaboration between the relevant specialties. Three care levels for fetal therapy centers are proposed to match the anticipated care complexity, with appropriate resources to achieve an optimal outcome at an institutional and regional level. A level I fetal therapy center should be capable of offering fetal interventions that may be associated with obstetric risks of preterm birth or membrane rupture but that would be very unlikely to require maternal medical subspecialty or intensive care, with neonatal risks not exceeding those of moderate prematurity. A level II center should have the incremental capacity to provide maternal intensive care and to manage extreme neonatal prematurity. A level III therapy center should offer the full range of fetal interventions (including open fetal surgery) and be able manage any of the associated maternal complications and comorbidities, as well as have access to neonatal and pediatric surgical intervention including indicated surgery for neonates with congenital anomalies