Students’ Perceived Benefits of Integrating a BSc in Health Sciences within a Medical Degree at Sultan Qaboos University

Objectives: After completing the pre-clinical phase of a Doctor of Medicine (MD) curriculum, undergraduate medical students may choose to add a Bachelor of Science (BSc) degree in health sciences to their MD degree. Limited data exists on the motives behind students’ decisions to undertake such intercalated degrees. Hence, this study aimed to identify the factors that influence students in making this choice. Methods: Undergraduate students who chose the research-based academic track of the intercalated phase of the BSc programme at the College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman, between 2014–2018 were enrolled. A standardised and validated self-explanatory questionnaire examining motivations to join the intercalated phase was administered to all students in the first week of enrolment. Results: Over a five-year period, out of 557 eligible students, 18 (3%) were enrolled in the intercalated phase and all completed the questionnaire. The mean age was 22 ± 1.5 years and the majority (83%) were female. Out of the 18 students, 10 (55%) had taken the university’s foundation programme. A total of 45% of students chose to intercalate out of their own interest, regardless of career ambitions. The main reasons to intercalate were an opportunity to enhance research experience, alignment with long-term career goals and a chance to publish in indexed journals. Conclusion: Despite the benefits of obtaining an additional degree, a relatively small proportion of MD students were attracted to the intercalated phase. A better presentation of the BSc degree is needed to help students make a more informed decision.Keywords: Medical Education; Undergraduate Medical Education; Career Choice; Curriculum; Oman

The Value of Programmed Death Ligand 1 Expression in Cancer Patients Treated with Neoadjuvant Chemotherapy

Programmed death ligand 1 (PD-L1) is an inhibitory molecule expressed by cancer cells to supress T-cell activity and escape anti-tumour immunity. The role of PD-L1 in cancer has been studied extensively as it is considered an important immune checkpoint against immune over-activation through its interaction with Programmed death receptor 1 (PD-1) expressed on activated lymphocytes. PD-L1 expression was found to be enhanced by chemotherapy through different proliferation pathways. However, the predictive and prognostic value for PD-L1 expression in cancer patients treated with neoadjuvant chemotherapy (NAC) is not yet established. This review focused on the potential effects of chemotherapy on PD-L1 expression and the role of PD-L1 as a prognostic and predictive marker in NAC-treated cancer patients. In addition, the potential use of this marker in clinical practice is discussed.Keywords: Programmed Cell Death 1 Ligand 1; Programmed Cell Death 1 Receptor; Neoadjuvant Therapy; Cancer

Accuracy of Platelet Counting by Optical and Impedance Methods in Patients with Thrombocytopaenia and Microcytosis

Objectives: Obtaining accurate platelet counts in microcytic blood samples is challenging, even with the most reliable automated haematology analysers. The CELL-DYN™ Sapphire (Abbott Laboratories, Chicago, Illinois, USA) analyser uses both optical density and electronic impedance methods for platelet counting. This study aimed to evaluate the accuracy of optical density and electrical impedance methods in determining true platelet counts in thrombocytopaenic samples with microcytosis as defined by low mean corpuscular volume (MCV) of red blood cells. Additionally, the impact of microcytosis on platelet count accuracy was evaluated. Methods: This study was carried out between February and December 2014 at the Haematology Laboratory of the Sultan Qaboos University Hospital in Muscat, Oman. Blood samples were collected and analysed from 189 patients with thrombocytopaenia and MCV values of <76 femtolitres. Platelet counts were tested using both optical and impedance methods. Stained peripheral blood films for each sample were then reviewed as a reference method to confirm platelet counts. Results: The platelet counts estimated by the impedance method were on average 30% higher than those estimated by the optical method (P <0.001). The estimated intraclass correlation coefficient was 0.52 (95% confidence interval: 0.41–0.62), indicating moderate reliability between the methods. The degree of agreement between methods ranged from -85.5 to 24.3 with an estimated bias of -30, suggesting that these methods generate different platelet results. Conclusion: The impedance method significantly overestimated platelet counts in microcytic and thrombocytopaenic blood samples. Further attention is therefore needed to improve the accuracy of platelet counts, particularly for patients with conditions associated with microcytosis

HIV-1 Viremia Prevents the Establishment of Interleukin 2–producing HIV-specific Memory CD4+ T Cells Endowed with Proliferative Capacity

CD4+ T cell responses are associated with disease control in chronic viral infections. We analyzed human immunodeficiency virus (HIV)-specific responses in ten aviremic and eight viremic patients treated during primary HIV-1 infection and for up to 6 yr thereafter. Using a highly sensitive 5-(and-6)-carboxyfluorescein diacetate-succinimidyl ester–based proliferation assay, we observed that proliferative Gag and Nef peptide-specific CD4+ T cell responses were 30-fold higher in the aviremic patients. Two subsets of HIV-specific memory CD4+ T cells were identified in aviremic patients, CD45RA− CCR7+ central memory cells (Tcm) producing exclusively interleukin (IL)-2, and CD45RA− CCR7− effector memory cells (Tem) that produced both IL-2 and interferon (IFN)-γ. In contrast, in viremic, therapy-failing patients, we found significant frequencies of Tem that unexpectedly produced exclusively IFN-γ. Longitudinal analysis of HIV epitope–specific CD4+ T cells revealed that only cells that had the capacity to produce IL-2 persisted as long-term memory cells. In viremic patients the presence of IFN-γ–producing cells was restricted to periods of elevated viremia. These findings suggest that long-term CD4+ T cell memory depends on IL-2–producing CD4+ T cells and that IFN-γ only–producing cells are short lived. Our data favor a model whereby competent HIV-specific Tcm continuously arise in small numbers but under persistent antigenemia are rapidly induced to differentiate into IFN-γ only–producing cells that lack self-renewal capacity

The Immunosuppressive Properties of the HIV Vpr Protein Are Linked to a Single Highly Conserved Residue, R90

BACKGROUND: A hallmark of AIDS progression is a switch of cytokines from Th1 to Th2 in the plasma of patients. IL-12, a critical Th1 cytokine secreted by antigen presenting cells (APCs) is suppressed by Vpr, implicating it as an important virulence factor. We hypothesize that Vpr protein packaged in the virion may be required for disabling APCs of the first infected mucosal tissues. Consistent with this idea are reports that defects in the C-terminus of Vpr are associated with long-term non-progression. PRINCIPAL FINDINGS: Vpr RNA amplified from various sources was electroporated into monocyte-derived DC and IL-12 levels in supernatants were analyzed. The analysis of previously reported C-terminal Vpr mutations demonstrate that they do not alleviate the block of IL-12 secretion. However, a novel single conservative amino acid substitution, R90K, reverses the IL-12 suppression. Analysis of 1226 Vpr protein sequences demonstrated arginine (R) present at position 90 in 98.8%, with other substitutions at low frequency. Furthermore, none of sequences report lysine (K) in position 90. Vpr clones harboring the reported substitutions in position 90 were studied for their ability to suppress IL-12. Our data demonstrates that none of tested substitutions other than K relieve IL-12 suppression. This suggests a natural selection for sequences which suppress IL-12 secretion by DC and against mutations which relieve such suppression. Further analyses demonstrated that the R90K, as well as deletion of the C-terminus, directs the Vpr protein for rapid degradation. CONCLUSION: This study supports Vpr as an HIV virulence factor during HIV infection and for the first time provides a link between evolutionary conservation of Vpr and its ability to suppress IL-12 secretion by DC. DC activated in the presence of Vpr would be defective in the production of IL-12, thus contributing to the prevailing Th2 cytokine profile associated with progressive HIV disease. These findings should be considered in the design of future immunotherapies that incorporate Vpr as an antigen

The Colocalization Potential of HIV-Specific CD8+ and CD4+ T-Cells is Mediated by Integrin β7 but Not CCR6 and Regulated by Retinoic Acid

CD4+ T-cells from gut-associated lymphoid tissues (GALT) are major targets for HIV-1 infection. Recruitment of excess effector CD8+ T-cells in the proximity of target cells is critical for the control of viral replication. Here, we investigated the colocalization potential of HIV-specific CD8+ and CD4+ T-cells into the GALT and explored the role of retinoic acid (RA) in regulating this process in a cohort of HIV-infected subjects with slow disease progression. The expression of the gut-homing molecules integrin β7, CCR6, and CXCR3 was identified as a “signature” for HIV-specific but not CMV-specific CD4+ T-cells thus providing a new explanation for their enhanced permissiveness to infection in vivo. HIV-specific CD8+ T-cells also expressed high levels of integrin β7 and CXCR3; however CCR6 was detected at superior levels on HIV-specific CD4+ versus CD8+ T-cells. All trans RA (ATRA) upregulated the expression of integrin β7 but not CCR6 on HIV-specific T-cells. Together, these results suggest that HIV-specific CD8+ T-cells may colocalize in excess with CD4+ T-cells into the GALT via integrin β7 and CXCR3, but not via CCR6. Considering our previous findings that CCR6+CD4+ T-cells are major cellular targets for HIV-DNA integration in vivo, a limited ability of CD8+ T-cells to migrate in the vicinity of CCR6+CD4+ T-cells may facilitate HIV replication and dissemination at mucosal sites

Maladies auto-immunes de l'oreille interne: étude sur la caractérisation des antigènes cochléaires et l'induction de ces maladies chez le cobaye

Thèse de doctorat en sciences biomédicales (immunologie) (SBIM 3)--UCL, 200

A New Cellular Weapon to Kill Leukaemic B-Cells

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Leishmania infantum and Epstein-Barr virus co-infection in a patient with hemophagocytosis

The authors describe a rare case of a 27-year old previously healthy male presenting with high grade fever, pancytopenia, hepatosplenomegaly, high levels of ferritin and triglyceride, suggesting a diagnosis of hemophagocytic lymphohistiocytosis (HLH) syndrome. Other investigations showed a positive Leishmania infantum serology and high Epstein-Barr virus (EBV) viremia. The diagnosis of a visceral leishmaniasis was confirmed by bone morrow biopsy, which showed Leishman-Donovan bodies and evidence of HLH. The patient received liposomal amphotericin B and he had a complete resolution of his symptoms and clearance of EBV viremia. This case of HLH associated with visceral leishmaniasis and EBV co-infection raises the question about the significance of EBV in patients with HLH. The treatment of actual etiological agent can lead to complete cure while using current recommend chemotherapy for HLH-related EBV in a patient with hidden infection may have deleterious effects