Protein engineering strategy for the stabilization of HIV-1 α-helical peptides

2019 Spring.Includes bibliographical references.Many disease-relevant protein-protein interactions (PPIs) contain an alpha helix and helical binding cleft at their interface. Disruption of these interactions with helical peptide mimics is a validated therapeutic strategy. However, short peptides typically do not fold into stable helices, which significantly lowers their in vivo stability. Researches have reported methods for helical peptide stabilization but, these approaches rely on laborious, and often expensive, chemical synthesis and purification. The research I have preformed aims to stabilize disease-relevant helices through protein engineering. In contrast to chemically constrained helical peptides, a protein can be expressed in a cellular system on a much larger scale. Recently, we reported a new strategy termed "helix-grafted display" that overcomes the traditional hurdles of helical mimics and applied it to the challenge of suppressing HIV entry. Our helix grafted proteins, potently inhibits formation of the extracellular PPI involving C-peptide helix, and HIV gp41 N-peptide trimer, as tested in HIV CD4+ cells. Further optimization of the helical sequence by yeast display yielded new proteins that suppress HIV-1 entry and express substantially better in E. coli. Furthermore, fusion proteins designed to improve the serum stability of these helix grafted proteins have been made that potently suppress HIV-1 entry. Collectively, I report a potential cocktail of evolved HIV-1 entry inhibitors that are functional against an Enfuvirtide-resistant strain and are designed for serum stabilities that rival current monoclonal antibody drugs

Evaluation of Mental Health Services in the Free State

No Abstract

Patterns and determinants of acute psychiatric readmissions

Objectives. Deinstitutionalisation and shortage of psychiatric beds worldwide has led to extensive research into the risk factors and interventions associated with rapid and recurrent admission to hospital. Little research of this nature has taken place in South Africa, particularly with regard to acute hospital admissions. This study attempted primarily to assess the effect of length of stay and administration of depot antipsychotics in hospital on time to readmission.Design. A retrospective cohort of 180 admissions was followed up for 12 months, after an index discharge, by means of multiple hospital and community-based record reviews. Each readmission was analysed as an event using a survival analysis model.Setting. Chris Hani Baragwanath Hospital, Gauteng.Subjects. A random sample of patients admitted during a 6- month period in 1996.Outcome measures. Time to readmission.Results. Two hundred and eighty-four admissions were analysed. The only factor that provided a significant protective effect was being married or cohabiting (P = 0.015). Clinic attendance showed a slight protective effect early on but conferred a significantly higher risk of readmission on those who had been out of hospital for a long period (P = 0.001). Only 21 % of discharged patients ever attended a clinic. The overall risk of readmission was significantly higher in the first 90 days post discharge.Conclusions. The lack of impact of length of hospital stay and use of depot neuroleptics on time to readmission may indicate that patients are being kept for appropriate duration and that the most ill patients are receiving depot medication.Several sampling and statistical artefacts may explain some of our findings. These results confirm the worldwide difficulty in finding consistent and accurate predictors of readmission. Low rates of successful referral to community aftercare need to be addressed before their effectiveness can be reasonably assessed. The inherent instability of the post-discharge period is a potential area for further investigation and intensive management

The Effect of Aortic Valve Replacement on Left Ventricular Function in Patients with Aortic Valvular Disease

Despite improved surgical techniques and survival in patients following aortic valve replacement for aortic stenosis and aortic insufficiency, the proper timing for surgery remains controversial. The incomplete reversibility of left ventricular dysfunction remains a concern, and postoperative improvement of left ventricular function is not consistently demonstrated. We studied 11 patients with aortic stenosis and nine patients with aortic insufficiency using angiographic and radioisotope assessment of left ventricular function preoperatively. Postoperative left ventricular function was assessed over nine to 13 months by radioisotope multiple-gated acquisition (MUGA) scan. All patients with impaired left ventricular function preoperatively showed slow but significant recovery toward a normal left ventricular ejection fraction by nine to 13 months postoperatively. Patients with aortic stenosis or aortic insufficiency and depressed left ventricular function can clearly obtain substantial, albeit delayed, improvement after valve replacement

A model for estimating mental health service needs in South Africa

Objective. To develop a model for estimating the services and human resources needed. to care for people with severe psychiatric conditions in a hypothetical population of 100 000 people in South Africa.Method. Annual mental health service needs were estimated. in terms of numbers of daily patient visits (DPV) in ambulatory care, the number of beds required, and staffing_ Developed within a spreadsheet format, the model allows for the adjustment of key service variables according.to estimated or existing service data.Results. At 100% coverage, 87 DPV, 28 acute beds, and 10 medium-long stay beds are necessary for a population of 100 000 people. This would require 352 full-time equivalent mental health staff: 21.3 for inpatient care, 12.0 for ambulatory care, and 1.9 for management.Conclusion. Because the model can produce a range of service recommendations, the assumptions that inform it should be clearly stated. and justified.. This method makes the assumptions on which services are planned. explicit and allows for a rational approach to decision making

Care of HIV-infected adults at Baragwanath Hospital, Soweto

Part I. Clinical management and costs of outpatient careObjective. To provide a detailed breakdown of clinical presentations and management of outpatients with HIV. and associated costs, in order to inform clinical practice, health service planning and projections of the costs of HIV care in South AfricaSetting. The outpatient department of a public sector, academic hospital in Soweto, South AfricaDesign. A retrospective, descriptive study using a record review and a combination of direct and step-down costing of health service costs (1992 prices).Patients. All 179 patients with HIV seen at the outpatient department between 1989 and 1992.Results. The average age at presentation was 30 years for men and 29 years for women. The most common clinical presentations at first viSIT were lymphadenopathy, weight loss, peripheraJ neuropathy and tuberculosis. Many patients, however, were asymptomatic. Analysis of clinical presentations, investigations and drugs used indicated that at least 80% of patients could have been managed at primary care leveL The average cost per consultation was R112.03. Costs per patient and per visit increased with stage of disease. Most of the costs arose from variable costs, which are influenced by clinical management decisions. Laboratory investigations (30%), staff (21 %) and drugs (22%), especially for fungal, viral and tuberculosis infection, were the major contributors to costs.Conclusions. Given projected HIV infection rates and the associated, potentially enormous costs of care revealed by this study, clinicians and health service planners must identify and implement cost-effective approaches to investigating, treating and meeting other health care needs of HIV-infected people. Treatment of people with HIV at primary care outpatient services seems both possible and potentially more cost-effective than hospital-level care in South Africa Emphasis should be placed on building primary level capacity to take on this role effectively. Further studies are required to identify the costeffectiveness, not only of treating HIV-related conditions, but also of treating other diseases if just and adequately infonned decisions about rationing of care are required in view of resource constraints

FERM3D: A finite element R-matrix electron molecule scattering code

FERM3D is a three-dimensional finite element program, for the elastic scattering of a low energy electron from a general polyatomic molecule, which is converted to a potential scattering problem. The code is based on tricubic polynomials in spherical coordinates. The electron-molecule interaction is treated as a sum of three terms: electrostatic, exchange. and polarisation. The electrostatic term can be extracted directly from ab initio codes ({\sc{GAUSSIAN 98}} in the work described here), while the exchange term is approximated using a local density functional. A local polarisation potential based on density functional theory [C. Lee, W. Yang and R. G. Parr, {Phys. Rev. B} {37}, (1988) 785] describes the long range attraction to the molecular target induced by the scattering electron. Photoionisation calculations are also possible and illustrated in the present work. The generality and simplicity of the approach is important in extending electron-scattering calculations to more complex targets than it is possible with other methods.Comment: 30 pages, 4 figures, preprint, Computer Physics Communications (in press