Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie - Volume 27, Issue 2, June 2008
Volume 27, Issue 2, June 2008
Die Afrikaner en skisofrenie : 'n genetiese studie : research and review article
Author J.L. Roos
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 27, pp 73 –87 (2008)
The Afrikaner and schizophrenia : a genetic study
An overview is given on the genetics of schizophrenia in an Afrikaner founder population. This research has been done over a period of ten years. Founder populations hold tremendous promise for mapping genes for complex traits, as they offer less genetic and environmental heterogeneity and greater potential for genealogical research. Not all founder populations are equally valuable, however. The Afrikaner population meets several criteria that make it an ideal population for mapping complex traits. These include founding by a small number of initial founders that likely allowed for a relatively restricted set of mutations and a large current population size that allows identification of a sufficient number of cases. Since a large number of patients was traced to an original founder couple, the genealogical data of the research support the hypothesis that a substantial portion of the schizophrenia cases the researchers have identified will share the same or a small number of susceptibility alleles. Results further show that genetic variation at the 22q11 locus enhances the risk to develop schizophrenia. More than one gene in this region can independently or synergistically increase the risk of schizophrenia in nondeleted patients. In three independent samples, evidence was provided for a contribution of the PRODH / DGCR6 locus in 22q11 associated schizophrenia. One of these samples was from South Africa as part of an ongoing collection of schizophrenia patients of Afrikaner origin. An unusual pattern of PRODH2 gene variation that mimics the sequence of a linked pseudogene was uncovered. Several of the pseudogene-like variants identified, resulted in missense changes at conserved residues and may prevent synthesis of a fully functional enzyme. The results have implications for understanding the genetic basis of the 22q11-associated psychiatric phenotype and provide further insight into the genomic instability of this region. It was shown in an independent sample of Afrikaner schizophrenia patients that the frequency of 22q11 deletion syndrome was 2%, as suggested in earlier studies. Early deviant behaviour before 10 years of age was the most important factor related to the onset of illness. Early deviant childhood behaviour was grouped into three clusters: social functioning impairment cluster, mood / anxiety cluster and cognitive impairment cluster. Some of these factors are important in male schizophrenia patients and may be used as endophenotypic markers. The LRRTM1 gene is implicated in the paternal transmission of schizophrenia. This gene may be implicated in the development of specific forebrain structures. It influences neuronal differentiation and connections. Male users of cannabis suffering from schizophrenia; with prominent early deviant behaviour have the lowest age of onset of illness, namely 18.4 years. Approximately half of the male schizophrenia patients and a quarter of the female schizophrenia patients used or abused cannabis. These figures are high and make cannabis use / abuse an important part of the management strategy of these patients. It was stated that in male patients with a specific subtype of schizophrenia (where early deviant behaviour was present) the use of cannabis triggers an illness with earlier onset and a poor prognosis. The prevalence of obsessive-compulsive disorder and obsessive-compulsive symptoms in Afrikaner patients suffering from schizophrenia was 13.25%. This finding differs from those in another ethnic group in South Africa suggesting the possible role of genetic and cultural factors in the prevalence of co-morbid OCD / OCS in this patient population. The most common obsession reported was contamination followed by religious obsession. The most common compulsion was checking behaviour.
Clinical characteristics of Afrikaner schizophrenia and schizo-affective disorder patients with and without co-morbid OCD / OCS are the same; both groups were associated with significant psychopathology and a poor prognosis.
Die artikel gee 'n oorsig oor navorsingbevindings die afgelope tien jaar oor die genetika van skisofrenie in die Afrikaner as 'n stigtersbevolking. Die genealogiese data in die studie steun die hipotese dat 'n aansienlike deel van die skisofrenie-pasiënte wat geïdentifiseer is, dieselfde of 'n klein aantal vatbaarheid-allele deel, omdat 'n groot aantal pasiënte teruggespoor kan word na 'n stigtersegpaar. Die resultate toon verder dat genetiese variase op die 22q11-lokus die risiko om die siekte te ontwikkel verhoog. Meer as een geen op hierdie gebied kan onafhanklik of sinergisties die risiko in pasiënte, waar die geen nie uitgewis is nie, verhoog. Die studie het ook, in 'n onafhanklike steekproef, bevestig dat die frekwensie van die 22q11-uitwissingsindroom in volwasse Kaukasiese skisofreniese pasiënte ongeveer 2% is, soos voorheen voorgestel. Vroeë afwykende gedrag is die belangrikste faktor wat die ouderdom van aanvang van siekte bepaal veral in manlike pasiënte met skisofrenie en is 'n moontlike endofenotipe merker. Die geen LRHTM1 (leusienryk-herhaaltransmembraan-neuronaal-1) word geïmpliseer by vaderlike oordrag van skisofrenie en skisoaffektiewe versteuring. Waarskynlik speel die geen 'n rol gedurende die ontwikkeling van spesifieke voorbreinstrukture, deur neuronale differensiasie en verbinding te beïnvloed. Manlike verbruikers van cannabis met ernstige vroeë afwykende gedrag het die laagste gemiddelde ouderdom van aanvang van siekte gehad, naamlik 18.4 jaar. Dit word geïnterpreteer dat in mans met 'n spesifieke subtipe van skisofrenie (waar vroeë afwykende gedrag teenwoordig is) cannabis die aanvang van siekte sal ontlont op 'n vroeër ouderdom en die psigose het gevolglik 'n swak prognose. Die voorkoms van obsessief-kompulsiewe versteuring en obsessief-kompulsiewe simptome in Afrikaner pasiënte met skisofrenie was 13.25%. Die algemeenste gerapporteerde obsessie was kontaminasie, gevolg deur geloofsobsessies. Die algemeenste kompulsie was nagaan-gedrag.
Die invloed van gesondheidsopvoeding op die prevalensie van skistosoombesmettings by leerders in 'n skistosoomendemiese gebied in die Limpopoprovinsie : research and review article
Authors: C.T. Wolmarans, J. Theron, S. Postma and K.N. De Kock
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 27, pp 88 –101 (2008)
The influence of health education on the prevalence of schistosome infected learners in a schistosome endemic area in the Limpopo Province
During this study selected direct and indirect educational methods were evaluated as a means of decreasing the prevalence of schistosome infections in school children living in a schistosome endemic area. Two direct (puppet show and flip chart) and three indirect (notice board, poster and education via parents or guardians) educational methods were evaluated. Schistosome infected learners were identified by means of parasitological methods, their knowledge concerning schistosomiasis was tested in a questionnaire and information regarding water and sanitation facilities at their disposal was collected. Local health authorities facilitated treatment for this disease, while local teachers were involved in conveying the various educational programmes. A noticeable increase in the learner's knowledge regarding schistosomiasis was evident after only two educational opportunities, while a significant decrease in the cumulative prevalence of infection was recorded during the investigation among all the groups receiving education. Statistical analyses revealed that the puppet show, flipchart and poster were the most effective methods used to lower the prevalence of infection, while involving parents or guardians in the process proved to be the least effective method employed during the study.
In hierdie studie is geselekteerde direkte en indirekte onderrigmetodes geëvalueer ten opsigte van hulle potensiaal om die prevalensie van skistosoombesmettings by skoolgaande kinders, woonagtig in 'n landelike omgewing in 'n skistosoom-endemiese gebied, te verlaag. Twee direkte (poppekas en blaaibord) en drie indirekte (plakkaat, kennisgewingbord en onderrig via ouers of voogde) onderrigmetodes is geëvalueer. Skistosoombesmette leerders is met behulp van parasitologiese metodes geïdentifiseer en aan 'n vraelys in hul moerdertaal onderwerp om onder andere op hoogte van hulle kennis ten opsigte van skistosomose te kom en te bepaal hoe die infrastruktuur tot hulle beskikking wat water en sanitasie betref, daar uitsien. Leerders is met behulp van plaaslike gesondheidspersoneel vir die siekte behandel en daarna op verskeie geleenthede in samewerking met plaaslike onderwysers aan die verskillende onderrigmetodes blootgestel. 'n Aansienlike toename in die leerders se kennis aangaande skistosomose is reeds na die tweede onderrigsessie waargeneem. Ten spyte van die feit dat die leerders in 'n skistosoom-endemiese gebied woonagtig was, het slegs 2% die siekte met 'n natuurlike waterhabitat soos 'n rivier geassosieer. Daar is verder gevind dat relevante amptelike strukture soos klinieke, geneeshere en skole byna geen rol speel in die verskaffing van inligting van wat die siekte behels en hoe dit oorgedra word nie. Betekenisvolle afnames in die kumulatiewe prevalensie van besmetting het by al die groepe, wat aan die onderskeie onderrigmetodes blootgestel was gedurende die ondersoek, voorgekom, wanneer dit met die kontrolewaarde waar die leerders geen onderrig ontvang het nie, vergelyk is. Statistiese vergelykings tussen die verskillende onderrigmetodes het getoon dat die poppekas, blaaibord en plakkaat die effektiefste was om die prevalensie te verlaag, terwyl die gebruik van ouers of voogde die minste effektief was. Alhoewel die kumulatiewe prevalensie van besmetting by laasgenoemde metode ook betekenisvol van die kontrolegroep verskil het, was bykans 50% van die "leerkragte" na een jaar nie meer betrokke nie en wil dit voorkom asof bemagtiging van plaaslike inwoners omskistosomose te help bekamp, soos in hierdie studie gepoog is, nie veel potensiaal inhou nie.
Logistieke aspekte van pypleidingvervoer in dievoorsiening van petroleumprodukte
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 27, pp 102 –122 (2008)
Pipeline transport is a non-containerised bulk mode of transport for the carriage of suitable liquids (for example, petroleum commodities, which include crude oil, refined fuel products and liquid petro-chemicals), gas, slurrified coal and certain water-suspended ores and minerals. In South Africa, petroleum products account for the majority of commercial pipeline traffic, followed by crude oil and natural gas.
There are three basic types of petroleum pipeline transport systems:
Collectively, these systems provide a continuous link between extraction, processing, distribution, and wholesalers' depots in areas of consumption.
The following activities are involved in the flow of goods between place of origin and place of consumption or application: (1) Demand forecasting, (2) Facility site selection, (3) Procurement, (4) Materials handling, (5) Packaging, (6) Warehouse management, (7) Inventory management, (8) Order processing, (9) Logistics communications, (10) Transport, (11) Reverse logistics.
Because cost is incurred without adding value each time goods are handled (activity 4) at a terminal or storage facility, a primary logistics objective is to eliminate handling wherever possible. With the carriage of crude oil and petroleum products by pipeline this objective is fully met. Commodity intake, haulage, and discharge are combined in one process, usually a remote-controlled operation. Pipeline transport is a non-containerised bulk mode of transport thereby obviating the need for packaging (activity 5) and returning empty containers. Pipelines provide a direct and long-term link between these origins and destinations. If necessary a continuous service can be provided with no need for a return trip or a reverse pumping process (activity 11). The elimination of handling, packaging and reverse logistics activities contribute substantially to the high measure of economies of scale that pipeline transport enjoys. The article provides a description of each of the eleven logistics activities in the context of pipeline transport.
Effective logistics service is a prerequisite to help ensure that customers receive the required products at the desired quality and quantity, where and when needed. The most pertinent determinants of logistics service performance are (1) suitability, (2) accessibility, (3) goods security, (4) transit time, (5) reliability and (6) flexibility. The article offers a discussion of the extent to which pipeline transport conforms to each of these measures of effectiveness.
Die kommersiële vervoer van ruolie en brandstofprodukte per pypleiding en die beoogde verdere investering in hierdie vervoermodus kry in Suid-Afrika toenemend aandag. Pypleidingvervoer is 'n grootmaat-, nie-behoueringsmetode van vervoer van geskikte vloeistowwe (byvoorbeeld petroleumkommoditeite wat ruolie, brandstofprodukte en vloeibare petrochemikalieë insluit), aardgas en geflodderiseerde grondstowwe. In Suid-Afrika verteenwoordig brandstofprodukte die grootste deel van kommersiële pypleidingverkeer, gevolg deur ruolie en aardgas.
Daar is drie basiese soorte petroleumpypleidingvervoerstelsels.
Pypleidingstelsels vir geraffineerde produkte
Saam verskaf hierdie stelsels 'n aaneenlopende verbinding tussen ontginning, verwerking, verspreiding en groothandeldepots in verbruiksgebiede.
Aangesien daar koste verbonde aan goederehantering by eindpunte en opbergingsfasiliteite is sonder dat dit waarde toevoeg tot die goedere, is dit 'n primêre oogmerk om hantering sover moontlik uit te skakel. Met die vervoer van ruolie en brandstofprodukte per pypleiding word volkome aan hierdie oogmerk voldoen. Net die kommoditeit beweeg - die pypleiding verskaf die nodige omhulsel en beskerming van die kommoditeit. Indien nodig kan 'n volgehoue diens gelewer word sonder die noodsaaklikheid van 'n terugrit of 'n terugpomp-proses. Die uitskakeling van hantering, verpakking en terugwaartse logistieke aktiwiteite dra aansienlik by tot die skaalvoordele wat pypleidingvervoer geniet.
Doeltreffende logistieke diens is 'n voorvereiste om te help verseker dat kliënte die verlangde goedere op die aangewese tyd by die bestemde plek in die vereiste toestand en hoeveelheid ontvang. Die vernaamste logistieke diensmaatstawwe is (1) geskiktheid, (2) toeganklikheid, (3) goederesekuriteit, (4) deurvoertyd, (5) betroubaarheid, en (6) buigsaamheid. Die artikel bied 'n uiteensetting van die mate waartoe pypleidingvervoer aan hierdie doeltreffendheidsmaatstawwe voldoen.
Sellulêre biomerkerresponse as maatstaf van gevoeligheid van klipmossels (Mollusca) vir kadmiumbesoedeling
Authors: A.J. Reinecke, W. Schoeman and S.A. Reinecke
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 27, pp 123 –142 (2008)
Cellular biomarker responses of limpets (Mollusca) as measure of sensitivity to cadmium contamination
Due to the availability and chemical nature of some heavy metals, sub-lethal toxicant levels may persist in the ocean waters and may cause physiological problems and toxicity in invertebrates and other marine organisms. Although studies of metal concentrations in False Bay showed relatively low mean concentrations of Cd, invertebrates such as molluscs, crustaceans and many other groups are able to accumulate high levels of heavy metals in their tissues and still survive in the heaviest polluted areas. They can accumulate numerous pollutants from natural waters in quantities that are many orders of magnitude higher than background levels. Bioaccumulation of cadmium in intertidal species could cause stress which may be measurable at the cellular level. A variety of limpet species that may serve as suitable ecotoxicological monitoring species occur in abundance on rocky shores along the South African coastline. The aim of this study was to obtain sensitivity data which could contribute to the selection of a suitable monitoring species and the eventual establishment of a species sensitivity distribution model (SSD) with a biomarker response as endpoint. The limpets Cymbula oculus, Scutellastra longicosta, Cymbula granatina and Scutellastra granularis as well as water samples were collected at two localities in False Bay, South Africa. Analysis of water and biological samples were done by atomic absorption spectrometry. Exposures were done to three different sublethal concentrations of cadmium in the laboratory in static flow tanks over three days. There was a moderate increase in cadmium body concentrations over time. Results obtained at three exposure concentrations showed no significant differences in metal concentrations between the different C. oculus samples. Significant differences were obtained between the control and the exposure groups for each exposure time except between the control and the 1mg/L CdCl2 exposure group after 24 and 72 hours of exposure. Cd body concentrations (soft tissue) varied between 4.56 and 21.41µg/g (wet mass).
Mean Cd concentrations in soft tissue of S. longicosta was considerably lower (varying between 1.18 and 19.58 µg/g Cd ) than in the tissues of C. oculus. The control group differed significantly from the 0.8 and 1 mg/L CdCl2 exposures after 48 and 72 hours.
Mean Cd body concentrations in S. granularis were the highest of all exposed species, reaching a level of 148 µg/g Cd at the highest exposure concentration and differed significantly from the means of the other samples of the 0.8 mg/L CdCl2 exposure group after 72 hours and from the 1 mg/L CdCl2 group after 24 hours. Significant differences were also obtained between the Cd body concentrations of C. granatina for the three exposure concentrations and three exposure times.
Lysosomal membrane integrity was determined for both exposed and control animals, using the neutral red retention assay. Three of the four species showed a significant decrease in retention times with an increase in Cd concentration. Inter-species differences in sensitivity to environmentally relevant cadmium concentrations were reflected in the biomarker responses. Based on reduction of NRR times, the order of relative sensitivity to cadmium was S. granularis > C. oculus> S. longicosta.> C.granatina.
Die bioakkumulasie van kadmium in tussengetyspesies kan stres veroorsaak wat op sellulêre vlak meetbaar is. Verskeie klipmosselspesies kom volop op rotse aan die Suid-Afrikaanse kuslyn voor en kan moontlik vir ekotokiskologiese monitering gebruik word. Die oogmerk van die studie was om sensitiwiteitsdata te verkry wat kan bydrae tot die kies van 'n geskikte spesie vir monitering en die uiteindelike daarstelling van 'n model vir spesie sensitiwiteitsverspreiding (SSV) wat 'n biomerkerrespons as eindpunt gebruik. Die klipmossels Cymbula oculus, Scutellastra longicosta, Cymbula granatina en Scutellastra granularis en watermonsters is in Valsbaai versamel. Analises van kadmium in water en biologiese monsters is met behulp van atoomabsorpsiespektrofotometrie uitgevoer. Blootstellings van organismes aan subletale vlakke van kadmium is uitgevoer in statiese vloeitenks oor 'n periode van drie dae. Daar was 'n matige toename in liggaamskonsentrasies van kadmium oor tyd. Resultate wat by drie blootstellingskonsentrasies gekry is, het geen betekenisvolle verskille in metaalkonsentrasies tussen die verskillende C. oculus monsters uitgewys nie. Betekenisvolle verskille tussen die kontrole en die blootstellingsgroepe vir elke individuele blootstellingstyd is vir die spesie verkry behalwe tussen die kontrole en die 1mg/L CdCl2 blootstellingsgroep na 24 en 72 uur van blootstelling. Cd liggaamskonsentrasies (sagteweefsel) het tussen 4.56 en 21.41µg/g (nat massa) gevarieer.
Gemiddelde Cd konsentrasies in sagteweefsel van S. longicosta was aansienlik laer (variërend tussen 1.18 en 19.58 µg/g Cd ) as in weefsel van C. oculus. Die kontrolegroep van hierdie spesie het betekenisvol verskil van die 0.8 en 1 mg/L CdCl2 blootstellings na 48 en 72 uur.
Gemiddelde Cd liggaamskonsentrasies in S. granularis was die hoogste van al die blootgestelde spesies en het 'n vlak van 148 µg/g Cd by die hoogste blootstellingskonsentrasie bereik en het betekenisvol verskil van die ander monsters se gemiddeldes met die uitsondering van die 0.8 mg/ L CdCl2 blootstellingsgroep by 72 uur en die 1 mg/L CdCl2 groep by 24 uur. Betekenisvolle verskille is ook verkry vir die liggaamskonsentrasies van Cd van C. granatina tussen die drie verskillende blootstellingskonsentrasies en drie blootstellingstye.
Integriteit van lisosoommembrane is bepaal met behulp van die neutraalrooi retensiemetode. Drie van die vier spesies het 'n betekenisvolle afname in retentsietye getoon met 'n toename in Cd konsentrasie. Tussenspesieverskille in gevoelighede vir omgewingsrelevante kadmiumkonsentrasies is deur die biomerkerresponse uitgewys. Gebaseer op die verlaging in NRR tye, is die volgorde van relatiewe gevoeligheid vir kadmium as volg: S. granularis > C. oculus> S. longicosta.> C. granatina.
Die Suid-Afrikaanse Akademie vir Wetenskap en Kuns : Afdeling Natuurwetenskappe : paper
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 27, pp 143 –164 (2008)
Die bestudering van 1-hidroksietilideen-1,1-difosfoniese suur en sy komplekse met behulp van Raman- en KMR-spektroskopie, W. Barnard
Die ontwikkeling van 'n kragtige piko-sekonde-laser vir maan-laserafstandsmeting, R.C. Botha
Skeiding van Zr en Hf deur fraksionele kristallisasie van K2Zr(Hf)F6 : 2 'n teoretiese en eksperimentele studie, D.J. Braken, G. Lachmann, H.M. Krieg en O.S.L. Bruinsma
Luminesserende eienskappe van Y2SiO5 : Ce nano-dunlagies, E. Coetsee, J.R. Botha, J.J. Terblans, H.C. Swart
'n Studie van turbulensie in akkresieskywe van dwergnovas en die invloed daarvan as 'n sneller vir uitbarstings, M. Erwee en P.J. Meintjies
Woordafbrekingstegnieke vir die Germaanse tale, M. Fick
Gepulseerde laserdeponering van platinum-gebaseerde allooie, R.A. Harris, H.C. Swart en J.J. Terblans
'n Model vir inligtingsekerheidsbestuur gebaseer op wêreld-standaarde, M.M. Lessing
Identifikasie en hantering van konseptuele probleme by studente in eerstejaarschemie, A.F. Marais
Metabolomiese profielbepaling van Pelargonium sidoides DC en P. reniforme CURT, J.E. Maree, A.M. Viljoen en M. Manley
Die problematiek van die begrip "oneindigheid" in wiskundeonderwys, R. Mathlener
Luminessensie-eienskappe van SrAl2O4 : Eu2+,Dy3+ fosfor, S. Nieuwoudt, J.J. Terblans, J. Ngaruiya, O.M. Ntwaeaborwa, E. Coetsee, K.T. Hillie en H.C. Swart
Produkontwikkeling vir speelterapie : die stimulasie van kinders met leerprobleme deur die gebruik van hulle sintuie, Y. Olivier
Die sosiale verantwoordelikheid van wetenskaplikes : wat dink ons studente?, D. Röhm
Die gebruik van satellietbeelde vir die waarneming van plantegroeiverandering : die impak van olifante onder verskillende bestuurstrategieë, C.A. Simms
'n Rangorde-algoritme vir akademiese tydskrifte, M.C. Strydom
Die elektriese resonantpunte van marmer, A.J. Swart en H.C. vZ Pienaar
Omrol van veldvoertuie, B.P. Uys
Die skeiding van sirkonium en hafnium deur middel van vloeistof-vloeistof-ekstraksie, D.J. van der Westhuizen, O.S.L. Bruinsma en G. Lachmann
Die ko-adsorpsie van H en CO op 'n model-ysteroppervlak, P. van Helden en E. van Steen