Linkage study of the low-density lipoprotein-receptor gene and cholesterol levels in an Afrikaner family : quantitative genetics and identification of a minor founder effect

CITATION: Brink, P. A. et al. 1990. Linkage study of the low-density lipoprotein-receptor gene and cholesterol levels in an Afrikaner family : quantitative genetics and identification of a minor founder effect. South African Medical Journal, 77:292-296.The original publication is available at http://www.samj.org.zaOverlap of clinical and biochemical characteristics between hypercholesterolaemia in members of the general population and familial hypercholesterolaemic (FH) individuals may lead to misdiagnosis. Quantitative analyisis of family data may circumvent this problem. A way of looking for an association between plasma cholesterol levels and restriction fragment length polymorphism markers (RFLP) on the low-density lipoprotein (LDL) receptor gene by using reference cholesterol distributions was explored. Linkage, with a logarithm of the odds (LOD) score of 6,8 at θ 0, was detected between cholesterol levels and the LDL receptor in an extended Afrikaner family. Two RFLP-haplotypes, one previously found in a majority of Afrikaner FH homozygotes, and a second, Stu I -, BstE II +, Pvu II +, Nco I +, were associated with high cholesterol levels in this pedigree.Publisher’s versio

Influence of the charge carrier tunneling processes on the recombination dynamics in single lateral quantum dot molecules

We report on the charge carrier dynamics in single lateral quantum dot molecules and the effect of an applied electric field on the molecular states. Controllable electron tunneling manifests itself in a deviation from the typical excitonic decay behavior which is strongly influenced by the tuning electric field and inter-molecular Coulomb energies. A rate equation model is developed to gain more insight into the charge transfer and tunneling mechanisms. Non-resonant (phonon-mediated) electron tunneling which changes the molecular exciton character from direct to indirect, and vice versa, is found to be the dominant tunable decay mechanism of excitons besides radiative recombination.Comment: 4 pages, 4 figure

Experimental imaging and atomistic modeling of electron and hole quasiparticle wave functions in InAs/GaAs quantum dots

We present experimental magnetotunneling results and atomistic pseudopotential calculations of quasiparticle electron and hole wave functions of self-assembled InAs/GaAs quantum dots. The combination of a predictive theory along with the experimental results allows us to gain direct insight into the quantum states. We monitor the effects of (i) correlations, (ii) atomistic symmetry and (iii) piezoelectricity on the confined carriers and (iv) observe a peculiar charging sequence of holes that violates the Aufbau principle.Comment: Submitted to Physical Review B. A version of this paper with figures can be found at http://www.sst.nrel.gov/nano_pub/mts_preprint.pd

The lived experience of health sciences students’ participation in an interprofessional community-based stroke class

Background. Collaborative approaches in healthcare contexts may provide better care for patients. Interprofessional circuit-based group therapy could counter profession-specific tribalism. There is no evidence on interprofessional education (IPE) community-based interventions on student learning in the health professions. Objective. To explore undergraduate health sciences students’ experience of being involved in community-based interprofessional circuit-based group therapy. Methods. Semi-structured interviews were inductively analysed exploring undergraduate health sciences students’ experience of involvement in an IPE community-based stroke intervention. Results. A total of 12 final-year students participated, with representation from physiotherapy, occupational therapy and speech therapy. This IPE opportunity beneficially impacted students’ collaborative competencies in knowledge, attitudes, skills and behaviours. This community-based rotation immersed students in a service-delivery environment where patient management was co-ordinated by a multiprofessional rehabilitation team. The integrated stroke circuit group activity aimed to enhance further interconnectedness between student participants. Students who were exposed to this clinical activity reported an understanding of (i) patients’ unique contexts; (ii) role development and complementary overlap between health professions; and (iii) the value of joint interventions to both patients and rehabilitation teams in resource-constrained settings. Conclusion. These students have been primed in their practice-readiness as healthcare professionals for the 21st century who will promote quality care, and embrace collaborative professional practice and person-centredness

Molecular characterization of methicillin-resistant Staphylococcus aureus isolates from a hospital in Ghana

Background: Methicillin-resistant  Staphylococcus aureus (MRSA) are a major cause of hospital- and community-acquired infection. They can colonize humans and cause a wide range of infections including pneumonia, endocarditis and bacteraemia. We investigated the molecular mechanism of resistance and virulence of MRSA isolates from a teaching hospital in Ghana.Methodology: A total of 91 S. aureus isolates constituted the initial bacterial sample. Identification of S. aureus was confirmed by the VITEK 2 system. The cefoxitin screen test was used to detect MRSA and antibiotic susceptibility was determined using the VITEK 2 system. The resistance (mecA, blaZ, aac-aph, ermC, and tetK) and virulence (lukS/F-PV, hla, hld and eta) genes were amplified by polymerase chain reaction (PCR) and positive samples subjected to DNA sequencing. Pulsed field gel electrophoresis (PFGE) was used to ascertain the relatedness of the isolates.Results: Fifty-eight of 91 (63.7%) isolates were putatively methicillin resistant by the phenotypic cefoxitin screen test and oxacillin MICs. However, 43 (47%) of the isolates were genotypically confirmed as MRSA based on PCR detection of the mecA gene. Furthermore, 37.9% of isolates displayed resistance to tetracycline, 19% to trimethoprim-sulphamethoxazole, 15.5% to clindamycin, 12.1% to gentamicin, 13.8% to ciprofloxacin and erythromycin, 6.9% to moxifloxacin and 7.0% to rifampicin. None of the isolates was positive for inducible clindamycin resistance. The prevalence of resistance (mecA, blaZ, aac(6’)-aph(2’’), tetK, and ermC) and virulence (hla and lukS/F-PV) genes respectively were 74%, 33%, 22%, 19%, 3%, 5% and 3%, with isolates organized in two highly related clades.Conclusion: Results indicate a fairly high occurrence of MRSA, which can complicate the effective therapy of S. aureus infections, necessitating surveillance and stringent infection control programmes to forestall its spread.Keywords: MRSA, mecA, blaZ, hla, lukS/F-P

Trans-arterial embolisation therapies for unresectable intrahepatic cholangiocarcinoma: A systematic review

Background: Unresectable intrahepatic cholangiocarcinoma (ICC) portends a poor prognosis despite standard systemic treatments which confer minimal survival benefits and significant adverse effects. This study aimed to assess clinical outcomes, complications and prognostic factors of TAE therapies using chemotherapeutic agents or radiation. Methods: A literature search and article acquisition was conducted on PubMed (MEDLINE), OVID (MEDLINE) and EBSCOhost (EMBASE). Original articles published after January 2000 on trans-arterial therapies for unresectable ICC were selected using strict eligibility criteria. Radiological response, overall survival, progression-free survival, safety profile, and prognostic factors for overall survival were assessed. Quality appraisal and data tabulation were performed using pre-determined forms. Results were synthesized by narrative review and quantitative analysis. Results: Twenty articles were included (n=929 patients). Thirty three percent of patients presented with extrahepatic metastases. After treatment, the average rate of complete and partial radiological response was 10% and 22.2%, respectively. Overall median survival time was 12.4 months with a median 30-day mortality and 1-year survival rate of 0.6% and 53%, respectively. Acute treatment toxicity (within 30 days) was reported in 34.9% of patients, of which 64.3% were mild to moderate in severity. The most common clinical toxicities were abdominal pain, nausea and vomiting, and fatigue. Multiplicity, localization and vascularity of the tumor may predict worse overall survival. Conclusions: Trans-arterial therapies are safe and effective treatment options which should be considered routinely for unresectable ICC. Consistent and standardized methodology and data collection is required to facilitate a meta-analysis. Randomized controlled trials will be valuable in the future

Recent advances in exciton based quantum information processing in quantum dot nanostructures

Recent experimental developments in the field of semiconductor quantum dot spectroscopy will be discussed. First we report about single quantum dot exciton two-level systems and their coherent properties in terms of single qubit manipulations. In the second part we report on coherent quantum coupling in a prototype "two-qubit" system consisting of a vertically stacked pair of quantum dots. The interaction can be tuned in such quantum dot molecule devices using an applied voltage as external parameter.Comment: 37 pages, 15 figures, submitted to New Journal of Physics, focus issue on Solid State Quantum Information, added reference

Can a Loan Valuation Adjustment (LVA) Approach Immunize Collateralized Debt from Defaults?

This study focuses on structuring tangible asset backed loans to inhibit their endemic option to default. We adapt the pragmatic approach of a margin loan in the configuring of collateralized debt to yield a quasi‐default‐free facility. We link our practical method to the current Basel III (2017) regulatory framework. Our new concept of the Loan Valuation Adjustment (LVA) and novel method to minimize the LVA converts the risky loan into a quasi risk‐free loan and achieves value maximization for the lending financial institution. As a result, entrepreneurial activities are promoted and economic growth invigorated. Information asymmetry, costly bailouts and resulting financial fragility are reduced while depositors are endowed with a safety net equivalent to deposit insurance but without the associated moral hazard between risk‐averse lenders and borrowers

Collateral and Debt Maturity Choice. A Signaling Model

This paper derives optimal loan policies under asymmetric information where banks offer loan contracts of long and short duration, backed or unbacked with collateral. The main novelty of the paper is that it analyzes a setting in which high quality firms use collateral as a complementary device along with debt maturity to signal their superiority. The least-cost signaling equilibrium depends on the relative costs of the signaling devices, the difference in firm quality and the proportion of good firms in the market. Model simulations suggest a non-monotonic relationship between firm quality and debt maturity, in which high quality firms have both long-term secured debt and short-term secured or non-secured debt.