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"Thiart, C"
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Africa Alive Corridors: Transdisciplinary Research based on African Footprints
2024
The idea of Africa Alive Corridors (AAC) evolved from Gondwana geological mapping to a comprehensive, more inclusive and dynamic approach to transdisciplinary research known as Earth Stewardship Science. Twenty designated corridors explore the geo-biological and cultural heritage of different regions of Africa over various periods, from deep time to the Anthropocene. Each corridor reveals a specific lens through which to investigate some of the rich scientific narratives embedded within it. The concept also facilitates learning and knowledge exchange across numerous disciplines: archeology, geology, geophysics, oceanography, glaciology, biology, botany, ecology, agriculture, engineering, spatial statistics, social sciences, and the humanities. This contribution analyses ten selected corridors in southern and western Africa, the Congo Basin, East Africa, and Madagascar. The various research themes explored include Earth impact hazard, origins of humankind, Snowball Earth, coastal food systems and conservation, the biogeography of lemurs, human settlement dynamics in Cameroon, tectonically linked earthquake occurrences in Algeria and Morocco, modelling land-use changes in the Western Rift Valley, trades and civilizations of the Mali Empire, Mbira music, and contemporary art. The ongoing work on these—and ten other—corridors has considerable potential to host new international collaborations to develop the links between society and natural sciences in Africa. Ultimately, AAC will benefit all stakeholders, especially the youth, in understanding and responding to societal needs and current global challenges.
Journal Article
Did lemurs have sweepstake tickets? An exploration of Simpson's model for the colonization of Madagascar by mammals
by
Thiart, C.
,
Stankiewicz, J.
,
Masters, J. C.
in
Animal and plant ecology
,
Animal, plant and microbial ecology
,
Biogeography
2006
Aim To investigate the validity of Simpson's model of sweepstakes dispersal, particularly as it applies to the colonization of Madagascar by African mammals. We chose lemurs as a classic case. Location The East African coast, the Mozambique Channel and Madagascar. Methods First, we investigated the assumptions underlying Simpson's statistical model as it relates to dispersal events. Second, we modelled the fate of a natural raft carrying one or several migrating mammals under a range of environmental conditions: in the absence of winds or currents, in the presence of winds and currents, and with and without a sail. Finally, we investigated the possibility of an animal being transported across the Mozambique Channel by an extreme climatic event like a tornado or a cyclone. Results Our investigations show that Simpson's assumptions are consistently violated when applied to scenarios of over-water dispersal by mammals. We suggest that a simple binomial probability model is an inappropriate basis for extrapolating the likelihood of dispersal events. One possible alternative is to use a geometric probability model. Our estimates of current and wind trajectories show that the most likely fate for a raft emerging from an estuary on the east coast of Africa is to follow the Mozambique current and become beached back on the African coast. Given prevailing winds and currents, transport from Madagascar to Africa is very much more likely than the reverse process. Freak transport by means of a hurricane or tornado is even less likely than rafting for mammals. Main conclusions Our models suggest that the scenario of sweepstakes dispersal that currently enjoys wide support is not valid at either the theoretical or the applied level when applied to the hypothetical invasion of Madagascar by African mammals. Alternative explanations should be sought.
Journal Article
ORIGINAL ARTICLE: Did lemurs have sweepstake tickets? An exploration of Simpson's model for the colonization of Madagascar by mammals
2006
Aim: To investigate the validity of Simpson's model of sweepstakes dispersal, particularly as it applies to the colonization of Madagascar by African mammals. We chose lemurs as a classic case. Location: The East African coast, the Mozambique Channel and Madagascar. Methods: First, we investigated the assumptions underlying Simpson's statistical model as it relates to dispersal events. Second, we modelled the fate of a natural raft carrying one or several migrating mammals under a range of environmental conditions: in the absence of winds or currents, in the presence of winds and currents, and with and without a sail. Finally, we investigated the possibility of an animal being transported across the Mozambique Channel by an extreme climatic event like a tornado or a cyclone. Results: Our investigations show that Simpson's assumptions are consistently violated when applied to scenarios of over-water dispersal by mammals. We suggest that a simple binomial probability model is an inappropriate basis for extrapolating the likelihood of dispersal events. One possible alternative is to use a geometric probability model. Our estimates of current and wind trajectories show that the most likely fate for a raft emerging from an estuary on the east coast of Africa is to follow the Mozambique current and become beached back on the African coast. Given prevailing winds and currents, transport from Madagascar to Africa is very much more likely than the reverse process. Freak transport by means of a hurricane or tornado is even less likely than rafting for mammals. Main conclusions: Our models suggest that the scenario of sweepstakes dispersal that currently enjoys wide support is not valid at either the theoretical or the applied level when applied to the hypothetical invasion of Madagascar by African mammals. Alternative explanations should be sought.
Journal Article
Internet-Based Cognitive Behavioral Therapy for Insomnia: A Health Economic Evaluation
2016
Abstract
Study Objectives:
Lost productivity caused by insomnia is a common and costly problem for employers. Although evidence for the efficacy of Internet-based cognitive behavioral therapy for insomnia (iCBT-I) already exists, little is known about its economic effects. This study aims to evaluate the cost-effectiveness and cost-benefit of providing iCBT-I to symptomatic employees from the employer's perspective.
Methods:
School teachers (N = 128) with clinically significant insomnia symptoms and work-related rumination were randomized to guided iCBT-I or a waitlist-control-group, both with access to treatment as usual. Economic data were collected at baseline and 6-mo follow-up. We conducted (1) a cost-effectiveness analysis with treatment response (Reliable Change [decline of 5.01 points] and Insomnia Severity Index < 8 at 6-month follow-up) as the outcome and (2) a cost-benefit analysis. Because both analyses were performed from the employer's perspective, we focused specifically on absenteeism and presenteeism costs. Statistical uncertainty was estimated using bootstrapping.
Results:
Assuming intervention costs of €200 ($245), cost-effectiveness analyses showed that at a willingness-to-pay of €0 for each positive treatment response, there is an 87% probability that the intervention is more cost effective than treatment as usual alone. Cost-benefit analyses led to a net benefit of €418 (95% confidence interval: −593.03 to 1,488.70) ($512) per participant and a return on investment of 208% (95% confidence interval: −296.52 to 744.35). The reduction in costs was mainly driven by the effects of the intervention on presenteeism and to a lesser degree by reduced absenteeism.
Conclusions:
Focusing on sleep improvement using iCBT-I may be a cost-effective strategy in occupational health care.
Clinical Trials Registration:
Title: Online Recovery Training for Better Sleep in Teachers with High Psychological Strain. German Clinical Trial Register (DRKS), URL: https://drks-neu.uniklinik-freiburg.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00004700. Identifier: DRKS00004700.
Commentary:
A commentary on this article appears in this issue on page 1767.
Journal Article
Utility of Host Markers Detected in Quantiferon Supernatants for the Diagnosis of Tuberculosis in Children in a High-Burden Setting
by
Walzl, Gerhard
,
Detjen, Anne K.
,
Thiart, Lani
in
Biomarkers - metabolism
,
Cellular biology
,
Child, Preschool
2013
The diagnosis of childhood tuberculosis (TB) disease remains a challenge especially in young and HIV-infected children. Recent studies have identified potential host markers which, when measured in Quantiferon (QFT-IT) supernatants, show promise in discriminating between Mycobacterium tuberculosis (M.tb) infection states. In this study, the utility of such markers was investigated in children screened for TB in a setting with high TB incidence.
76 children (29% HIV-infected) with or without active TB provided blood specimens collected directly into QFT-IT tubes. After overnight incubation, culture supernatants were harvested, aliquoted and frozen for future immunological research purposes. Subsequently, the levels of 12 host markers previously identified as potential TB diagnostic markers were evaluated in these supernatants for their ability to discriminate between M.tb infection and disease states using the Luminex platform. Of the 76 children included, 19 (25%) had culture confirmed TB disease; 26 (46%) of the 57 without TB had positive markers of M.tb infection defined by a positive QFT-IT test. The potentially most useful analytes for diagnosing TB disease included IFN-α2, IL-1Ra, sCD40L and VEGF and the most useful markers for discriminating between QFT-IT positive children as TB or latent infection included IL-1Ra, IP-10 and VEGF. When markers were used in combinations of four, 84% of all children were accurately classified into their respective groups (TB disease or no TB), after leave-one-out cross validation.
Measurement of the levels of IFN-α2, IL-1Ra, sCD40L, IP-10 and VEGF in QFT-IT supernatants may be a useful method for diagnosing TB disease and differentiating between active TB disease and M.tb infection in children. Our observations warrant further investigation in larger well-characterized clinical cohorts.
Journal Article
Human immunodeficiency virus (HIV) infection in men with penile carcinoma is associated with increased prevalence of human papilloma virus infection and younger age at presentation
2018
Background: We investigated the prevalence of HIV and human papilloma virus (HPV) infection in men with penile carcinoma. Method: This retrospective study investigated all men with penile carcinoma at the Universitas Academic Hospital in Bloemfontein, South Africa (January 2000–December 2008). Patients' age, HIV status, histological type of carcinoma and evidence of HPV infection were recorded. Statistical analyses included Student's t-test and Fisher's exact test where appropriate (2-tailed p-value < 0.05 indicated statistical significant). Results: Among 65 patients (mean age 50.9 years, range 37–69), the most common histological type was squamous cell carcinoma (80.0%). HIV status was known for 48 patients; 27 (56.2%) were HIV-positive. The mean age at presentation was 43.7 years (range 26–69) years in the HIV-positive and 57.2 years (range 26–89) years in the HIV-negative group. Approximately 55% of HIV-positive and 24% of HIV-negative patients showed histological evidence of HPV infection (p = 0.04). No significant difference was found with regard to histological type of carcinoma. Conclusion: Patients with penile carcinoma had a high prevalence of HIV infection. The HIV-positive group were significantly younger at presentation, with a higher prevalence of HPV infection, suggesting that HIV may contribute to HPV-associated penile cancer at a younger age.
Journal Article
Acute helminth infection enhances early macrophage mediated control of mycobacterial infection
by
van Helden, P D
,
du Plessis, N
,
Thiart, L
in
631/250/2504/342/1927
,
631/250/255/1715
,
631/250/255/1856
2013
Co-infection with mycobacteria and helminths is widespread in developing countries, but how this alters host immunological control of each pathogen is not comprehensively understood. In this study, we demonstrate that acute Nippostrongylus brasiliensis (Nb) murine infection reduce early pulmonary mycobacterial colonization. This Nb-associated reduction in pulmonary Mycobacterium tuberculosis colony-forming units was associated with early and increased activation of pulmonary CD4 T cells and increased T helper type 1 (Th1) and Th2 cytokine secretion. An accelerated and transient augmentation of neutrophils and alveolar macrophages (AMs) was also observed in co-infected animals. AMs displayed markers of both classical and alternative activation. Intranasal transfer of pulmonary macrophages obtained from donor mice 5 days after Nb infection significantly reduced pulmonary Mycobacterium bovis Bacille Calmette–Guérin clearance in recipient mice. These data demonstrate that early stage Nb infection elicits a macrophage response, which is protective during the early stages of subsequent mycobacterial infection.
Journal Article
Establishing a consensus on research priorities in orthopaedic trauma within South Africa
by
Sluis-Cremer, Timothy
,
Thiart, Marí
,
Mukabeta, Takura D. M
in
Orthopedics
,
Trauma
,
Trauma care
2023
BackgroundMusculoskeletal (MSK) injuries are one of the leading causes of disability worldwide. Despite improvements in trauma-related morbidity and mortality in high-income countries over recent years, outcomes following MSK injuries in low- and middle-income countries, such as South Africa (SA), have not. Despite governmental recognition that this is required, funding and research into this significant health burden are limited within SA. This study aims to identify research priorities within MSK trauma care using a consensus-based approach amongst MSK healthcare practitioners within SA.MethodMembers from the Orthopaedic Research Collaboration in Africa (ORCA), based in SA, collaborated using a two round modified Delphi technique to form a consensus on research priorities within orthopaedic trauma care. Members involved in the process were orthopaedic healthcare practitioners within SA.ResultsParticipants from the ORCA network, working within SA, scored research priorities across two Delphi rounds from low to high priority. We have published the overall top 10 research priorities for this Delphi process. Questions were focused on two broad groups—clinical effectiveness in trauma care and general trauma public health care. Both groups were represented by the top two priorities, with the highest ranked question regarding the overall impact of trauma in SA and the second regarding the clinical treatment of open fractures.ConclusionThis study has defined research priorities within orthopaedic trauma in South Africa. Our vision is that by establishing consensus on these research priorities, policy and research funding will be directed into these areas. This should ultimately improve musculoskeletal trauma care across South Africa and its significant health and socioeconomic impacts.
Journal Article
The UMD‐LDLR database: additions to the software and 490 new entries to the database
by
Thiart, Rochelle
,
Rabès, Jean‐Pierre
,
Kotze, Maritha J.
in
Databases, Genetic - trends
,
familial hypercholesterolemia
,
Genes - genetics
2002
Mutations in the LDL receptor gene (LDLR) cause familial hypercholesterolemia (FH), one of the most frequent hereditary dominant disorders. The protein defect was identified in 1973, the gene was localized by in situ hybridization in 1985, and since, a growing number of mutations have been reported. The UMD‐LDLR database is customized software that has been developed to list all mutations, and also to provide means to analyze them at the nucleotide and protein levels. The database has been recently modified to fulfill the recommendations of the Nomenclature Working Group for human gene mutations. However, in the current version, both the nomenclature and usual LDLR gene mutation names are reported since the latter are more commonly used. The software has also been modified to accommodate the splicing mutations and alleles that carry two nucleotide variations. The current version of UMD‐LDLR contains 840 entries, of which 490 are new entries. Point mutations account for 90% of all mutations in the LDLR gene; the remaining are mostly major rearrangements, due to the presence of Alu sequences. Three new routines have been implemented in the software, thus giving users access to 13 sorting tools. In addition to the database, a Web site containing information about polymorphisms, major rearrangements, and promoter mutations is available. Both are accessible to the scientific community (www.umd.necker.fr) and should help groups working on LDLR to check their mutations and identify new ones, and greatly facilitate the understanding of functional classes/genotype relationships and of genotype/phenotype correlations. © 2002 Wiley‐Liss, Inc.
Journal Article
Management of non-healable and maintenance wounds: a systematic integrative review and referral pathway
by
Idensohn, PJ
,
Boersema, GC
,
Smart, H
in
atypical wound
,
Chronic illnesses
,
Clinical practice guidelines
2021
ObjectiveThis systematic integrative review aims to identify, appraise, analyse, and synthesise evidence regarding non-healable and maintenance wound management to guide clinical practice. An interprofessional referral pathway for wound management is proposed.Data sourcesAn electronic search of Scopus, Web of Science, PubMed, Academic Search Ultimate, Africa-Wide Information, Cumulative Index of Nursing and Allied Health Literature database with Full Text, Health Source: Consumer Edition, Health Source: Nursing/Academic Edition, and MEDLINE was conducted for publications from 2011 to 2019. Search terms included (non-healable/non-healing, chronic, stalled, recurring, delayed healing, hard-to-heal) and wound types most associated with non-healable or maintenance wounds. Published studies were hand searched by the authors.Study selectionStudies were appraised using two quality appraisal tools. Thirteen reviews, six best-practice guidelines, three consensus studies, and six original non-experimental studies were selected.Data extractionData were extracted using a coding framework including treatment of underlying causes, patient-centred concerns, local wound care, alternative outcomes, health dialogue needs, challenges within resource restricted contexts, and prevention.Data synthesisData were clustered by five wound types and local wound bed factors; further, commonalities were identified and reported as themes and subthemes.ConclusionsStrong evidence on the clinical management of non-healable wounds is limited. Few studies describe outcomes specific to maintenance care. Patient-centred care, timely intervention by skilled healthcare providers, and involvement of the interprofessional team emerged as the central themes of effective management of maintenance and non-healable wounds.
Journal Article