The fundamental flaw of the HSAB principle is revealed by a complete speciation analysis of the [PtCl(6-n)Br(n)](2-) (n = 0-6) system.

Bjerrum's model of step-wise ligand exchange is extended to compute a complete speciation diagram for the [PtCl6-nBrn](2-) (n = 0-6) system including all 17 equilibrium constants concerning the Pt(IV) chlorido-bromido exchange reaction network (HERN). In contrast to what the hard soft acid base (HSAB) principle "predicts", the thermodynamic driving force for the replacement of chloride by bromide in an aqueous matrix, for each individual ligand exchange reaction present in the Pt(IV) HERN, is due to the difference in halide hydration energy and not bonding interactions present in the acid-base complex. A generalized thermodynamic test calculation was developed to illustrate that the HSAB classified class (b) metal cations Ag(+), Au(+), Au(3+), Rh(3+), Cd(2+), Pt(2+), Pt(4+), Fe(3+), Cd(2+), Sn(2+) and Zn(2+) all form thermodynamically stable halido complexes in the order F(-) ≫ Cl(-) > Br(-) > I(-) irrespective of the sample matrix. The bonding interactions in the acid-base complex, e.g. ionic-covalent σ-bonding, Π-bonding and electron correlation effects, play no actual role in the classification of these metal cations using the HSAB principle. Instead, it turns out that the hydration/solvation energy of halides is the reason why metal cations are categorized into two classes using the HSAB principle which highlights the fundamental flaw of the HSAB principle.

An analysis of complaints against oral health professionals charged with misconduct at the HPCSA: 2004-2009.

AIM: This study investigates the nature, frequency, and outcome of complaints relating to misconduct laid against oral healthcare professionals (OHPs), charged with misconduct in South Africa. METHODS: Records of the Health Professions Council of South Africa (2004-2009) were analysed and classified using the ethical rules as a reference. "Clinically-related complaints" and "fraud" were added as extra categories. The nature and outcome of the complaints and the penalties were quantified, and the detailed nature of the complaints was qualitatively reported. RESULTS: Two percent of the registered dentists and 5.5% of the registered dental therapists were charged with misconduct. Clinically related complaints (59%) and fraud (29%) were most prevalent amongst the accused dentists. Fraud (46%), clinically related complaints (19%), advertising (15%), infection control (8%), and creating expectations that could not be met (8%) were the most common complaints against dental therapists. CONCLUSIONS: Substandard dental treatment and fraud were the main reasons for patient dissatisfaction that led to OHPs being charged with misconduct. Both these undesirable practices may be financially motivated. OHPs should take cognisance of these statistics and should adjust their professional approach accordingly in order to reflect acceptable ethical behaviour.

Trends in dental caries prevalence, severity and unmet treatment need levels in South Africa between 1983 and 2002.

OBJECTIVES: To determine trends in dental caries prevalence, severity and unmet treatment need levels amongst South African children. METHODOLOGY: Data obtained from three National Oral Health surveys (1982, 1988/89, 1999/2002) was used. RESULTS: Prevalence of caries amongst 12-year-old children decreased from 64.4% (1982) through 54.9% (1988/89) to 41.7% (1999/2002) and the DMFT decreased significantly (p < 0.05) from 2.54 (1982) through 1.73 (1988/89) to 1.17 (1999/2002). Unmet treatment need increased from 70.5% (1982), 72.3% (1988/89) to 75.2% (1999/2002). Significant decreases (p < 0.05) were recorded in the DMFT (1982-2002) in White, 75.3%; Asian, 64.1%; Black, 49.8%; and Coloured groups, 44.8%. High levels of untreated caries (D) and very low levels of treatment (M and F) were also observed. The highest mean dmft/DMFT for 6- and 12-year-olds respectively were recorded in the coastal areas of Metro Cape (5.1/1.86); followed by Port Elizabeth (3.86/1.37) and Durban (3.42/1.33); and the lowest in the interior--Bloemfontein (2.47/0.73). CONCLUSIONS: Caries reduced significantly during the past 20 years; is more prevalent and severe amongst Coloured and Black population groups and in coastal regions compared to the interior region. Unmet treatment need in 12- and 15-year-old children increased and more than 70% of caries in 6-, 12- and 15-year-old children go untreated.

Characterization of a spray-dried soymilk powder and changes observed during storage.

Physical characterization of a soymilk powder was carried out by electron microscopy. Chemical characterization was analyzed by proximate analysis, mineral composition by atomic absorption spectrometry, fatty acid composition by gas chromatography and protein composition by electrophoresis. The powder consists of large granules of 60-80 µm, which may be hollow, with smaller granules of 10-20 µm attached to them. Powder particles are covered by a layer of fat. During storage at 25 °C fat is spreading over the surface, while at -12 °C the fat is contracting. This change affected chemical stability, resulting in high level of fat oxidation when stored at 4 °C or 25 °C as well as a decrease in unsaturated fatty acids. Storage also affected the chemical properties of the re-constituted soymilk; the pH of a 12% soy powder suspension increased from 6.68 ± 0.05 to 7.06 ±0.08 after 12 months of storage. Storage temperature did not affect the pH of the suspension and this change could also not be ascribed to protein aggregation.

Musculoskeletal disorders amongst practising South African oral hygienists.

OBJECTIVES: The study sought to determine the level of musculoskeletal disorders among working oral hygienists in South Africa and potential determinants that are associated with these disorders. METHODS: Oral hygienists registered with the HPCSA were requested to complete an anonymous questionnaire. Apart from demographic information they were asked to report on any musculoskeletal symptoms experienced in the hands, neck, shoulders and lower back as well as details of workload, types of scaling procedures, size of instruments, the mobility of the operator's chair and the adjustability of patient chairs. RESULTS: Of the 362 respondents, 61.3%, 66.5%, 56.6% and 59.6%, experienced hand, neck, shoulder and lower back symptoms respectively. Twenty-eight percent of the respondents performed hand-scaling for more than four hours per day. Twenty-six percent reported immobile operator chairs, while 12.6% reported patient chairs that were difficult to adjust. Employing multivariate analysis, excessive hand scaling was associated with hand and shoulder symptoms, while immobile operator's chairs and poorly adjustable patient chairs were respectively associated with neck and lower back problems. CONCLUSIONS: The prevalence of work-related musculoskeletal disorders in practising oral hygienists in South Africa appears to be similar to that in developed countries. Significant determinants of musculoskeletal disorders may be immobile operator stools, poorly adjustable patient chairs and excessive hand-scaling daily.

Empirical support for a fissure sealant placement timeframe protocol for black South Africans.

OBJECTIVES: It is recommended that fissure sealants should be placed within four years after eruption. Due to considerable variations in the eruption times of molar teeth, this recommendation is of limited value from a public health perspective. This study, therefore, sought to provide empirical support for a public health fissure sealant placement timeframe protocol. METHODS: The first and second molar eruption patterns of black South African children aged five to seven and 11 to 16 years were analysed in relation to caries experience using the 1999/2002 National Children's Oral Health Survey. RESULTS: By seven years of age, 90% of first molars had erupted with a caries experience of 3%. By 14 years of age the erupted first molars caries experience was 20%. The 13- and 14-year-olds presented with 86% and 98% erupted second molars with a caries experience of 11% and 20%, respectively. CONCLUSIONS: The study findings suggest that during school-based fissure sealant programmes involving black South African children, first molars should be targeted at age seven (Grade 1), or as soon as possible thereafter. However, caries protection may still be achieved until thirteen years of age (Grade 7). Furthermore, second molars should be sealed between the age of 11 and 13 years (grades 5-7).

Differences in the clinical appearances of white versus black patients with facial cleft deformities: a retrospective study of a South African clinic.

OBJECTIVE: The purpose of this study was to determine the difference in prevalence of the different categories of facial cleft deformities between the white and black patients in a database of 2806 cleft cases at the University of Pretoria. No variation of clefts between these two groups has ever been compared previously. For this purpose, the clefts were classified according to the system described by Bütow in 1985. MATERIAL AND METHODS: Records of 2806 patients attending the university's cleft lip and palate clinic, between August 1983 and February 2006, were reviewed. The study group included cleft patients with syndromic and nonsyndromic CL, CLA, CLAP, hP, hPsP, sP, COMBI clefts with or without oblique or transverse facial (or Tessier) clefts. Very few of the cases presented with speech problems only, but with no clefts. The cleft categories of cleft lip, cleft palate and cleft lip and palate, as well as their subdivisions, were analysed. RESULTS: Of these cleft patients, 2003 were white patients and 665 were black patients; the rest were Indian, Coloured and East-Asian patients. In the black and the white population groups (n = 2668), there were more males with cleft in the white group (58.2%), but more females with clefts in the black group (54.9%). The most common cleft type generally was the cleft lip, alveolus and palate cleft (CLAP) with a 434% prevalence of white patients and 296% of black patients. The most common cleft in the black patients was the cleft palate at 435%, which was only recorded in 35.0% of the white patients. The frequency of the other orofacial clefts in decreasing order was: sP 19.4% for white and 21.2% for black; hPsP 15.2% for white and 21.2% for black; CLA 9.7% for white and 19.8% for black; CL 5.9% for white and 4.5% for black and combinations of different orofacial clefts (COMBI), 6.0% for white and 2.6% for black. The isolated hard palate cleft (hP) occurred very rarely (0.4% for white and 1.1% for black). The left side of the face was more often afflicted (left to right 51.6% to 28.5% for white; and 35.0% to 37.9% for black). In 0.5% (white) and 3.9% (black) median clefts were observed. CONCLUSION: A retrospective study was done of 2806 facial black patients (2668 cases). There was a considerable variation between the groups of orofacial clefts occurring in the two groups.

Mandibular fractures: an epidemiological survey at the Oral and Dental Hospital, Pretoria.

OBJECTIVE: The objective of this retrospective analysis was to study the etiology, distribution, treatment modalities and complications of mandibular fractures of patients who attended the Maxillo-Facial and Oral Surgery (MFOS) unit at the School of Dentistry, University of Pretoria. METHOD: The records of a representative sample of patients who presented at the MFOS unit with mandibular fractures between January 1999 and December 2003 were captured on a data form specifically designed for this purpose. The data were then analysed using the Statistix 8 programme. RESULTS: Of the 501 patients who were included in the survey, 67.6% were in the age group 21 to 40 years. The majority of the patients (83.2%) were male. Assault (72.5%) was the most common cause of injury followed by road traffic accidents (14.2 %) and falls (8.8%). Of the 501 cases, 41.3% were bilateral, 32.7% on the left side and 26% on the right side. With regard to the location of the fractures, the majority occurred in the body of the mandible (411%), followed by those in the area of the symphysis/ parasymphysis (23.1%). In the majority of cases (51.7%) the treatment modality used was a closed reduction with intermaxillary fixation. Complications were reported in 14.6% of the 501 cases of which malunion (32%) was the most prevalent. CONCLUSIONS: Mandibular fractures are more common in males in the age range 21 to 40 years. Interpersonal violence is the main cause of these fractures. The majority of mandibular fractures occur in the body region while malunion is the most common complication.

Socio-economic inequities in dental caries experience of 12-year-old South Africans: policy implications for prevention.

OBJECTIVES: To examine the socioeconomic inequities in dental caries experience of 12-year-olds, in order to inform policy actions for caries prevention in South Africa. METHODS: Secondary analysis of the 1999-2002 national survey data of 12-year-olds (N=5411), available from 37 regions in 7 of the 9 provinces, was carried out. Logistic regression was used to determine risks for caries experience among 12-year-olds in each province, using parental occupation and racial group as independent variables. Regression curve-estimation was used to examine the spatial relationship between mean DMFT and caries prevalence. RESULTS: The mean DMFT (+/-SD) for the study population was 1.19 (+/-2.13), significant caries index was 3.35 and caries prevalence was 40.1%. The highest mean DMFT was among the Coloured population (2.14+/-2.50). Compared to children in the highest occupational class, the risk for children of the unemployed to experience caries was lower in the North West province (Odds ratio [OR]=0.47; p<0.01), but significantly higher in the coastal provinces-- KwaZulu-Natal and Northern Cape, with OR of 1.32 and 1.52 respectively. The regression curve derived demonstrated that a unit increase in caries experience in low-level caries populations would generate more cases than similar increase in high-level caries populations. CONCLUSIONS: DMFT alone provided an incomplete picture of the impact of caries in South Africa, thus the need to monitor inequities as part of policy impact. The distribution of caries suggests that 'high-risk' approach to prevention in the presence of existing social gaps may inadvertently reinforce inequities in caries-burden and supports the concurrent implementation of population-approach, such as water fluoridation.

Acetylsalicylic acid as antifungal in Eremothecium and other yeasts.

Interesting distribution patterns of acetylsalicylic acid (ASA, aspirin) sensitive 3-hydroxy (OH) oxylipins were previously reported in some representatives of the yeast genus Eremothecium--an important group of plant pathogens. Using immunofluorescence microscopy and 3-OH oxylipin specific antibodies in this study, we were able to map the presence of these compounds also in other Eremothecium species. In Eremothecium cymbalariae, these oxylipins were found to cover mostly the spiky tips of narrowly triangular ascospores while in Eremothecium gossypii, oxylipins covered the whole spindle-shaped ascospore with terminal appendages. The presence of these oxylipins was confirmed by chemical analysis. When ASA, a 3-OH oxylipin inhibitor, was added to these yeasts in increasing concentrations, the sexual stage was found to be the most sensitive. Our results suggest that 3-OH oxylipins, produced by mitochondria through incomplete beta-oxidation, are associated with the development of the sexual stages in both yeasts. Strikingly, preliminary studies on yeast growth suggest that yeasts, characterized by mainly an aerobic respiration rather than a fermentative pathway, are more sensitive to ASA than yeasts characterized by both pathways. These data further support the role of mitochondria in sexual as well as asexual reproduction of yeasts and its role to serve as a target for ASA antifungal action.

Dieldrin resistance in the malaria vector Anopheles gambiae in Ghana.

Anopheles gambiae Giles s.s. (Diptera: Culicidae) is one of the principal vectors of malaria in the Ashanti region of central Ghana. High levels of resistance to dieldrin were recorded in a wild-caught sample from Obuasi (south of Kumasi) as well as a laboratory colony established using material from the wild population. Cytogenetic analysis of wild-caught and laboratory samples revealed chromosomal polymorphism for inversions 2La and 2Rb. Although inversion 2La has previously been shown to be associated with dieldrin resistance in certain other laboratory strains originating from West Africa, there was no obvious association between inversion karyotype assortment and the resistance phenotype in the Obuasi population. In addition, polymerase chain reaction analysis indicated the presence of the alanine296 to glycine mutation in the GABA (gamma amino-butyric acid) receptor (which has been mapped to a chromosomal position within inversion 2La). This mutation has previously been shown to be associated with dieldrin resistance in the same An. gambiae laboratory strains of West African origin. Our data show only a weak association between the dieldrin resistance phenotype and the presence of this mutation, suggesting that another dieldrin resistance mechanism is operational in the Obuasi population. Biochemical and synergist exposure assays suggest a metabolic component, probably mediated by monooxygenase P450 enzymes. We conclude that dieldrin resistance in the An. gambiae population of the Obuasi region occurs at a high level - most likely in the absence of selection - and that control of the resistance phenotype is polyfactorial and must include components other than mutations in the GABA receptor locus.

Oxylipin covered ascospores of Eremothecium coryli.

Eremothecium coryli is known to produce intriguing spindle-shaped ascospores with long and thin whip-like appendages. Here, ultra structural studies using scanning electron microscopy, indicate that these appendages serve to coil around themselves and around ascospores causing spore aggregation. Furthermore, using immunofluorescence confocal laser scanning microscopy it was found that hydrophobic 3-hydroxy oxylipins cover the surfaces of these ascospores. Using gas chromatography-mass spectrometry, only the oxylipin 3-hydroxy 9:1 (a monounsaturated fatty acid containing a hydroxyl group on carbon 3) could be identified. Sequential digital imaging suggests that oxylipin-coated spindle-shaped ascospores are released from enclosed asci probably by protruding through an already disintegrating ascus wall.

Insecticide resistance in malaria vector mosquitoes in a gold mining town in Ghana and implications for malaria control.

Malaria control programmes in Africa, for the most part, address only treatment of the disease and supply of insecticide treated bed nets. The impact of these restricted programmes has been limited and new approaches are being advocated, including integrated vector management strategies and partnerships with industry. Mosquito surveys were carried out for AngloGold/Ashanti in preparation for their implementation of an integrated malaria control programme at the Obuasi gold mine in Ghana. Malaria vectors that were collected inside houses were identified to species and molecular forms by PCR, and tested for insecticide resistance using standard WHO bioassays and molecular target site insensitivity (kdr) assays. Species were identified as An. funestus s.s. and An. gambiae S and M forms. The An. gambiae S form samples showed resistance to DDT, pyrethroids and carbamates while An. funestus was resistant to DDT and carbamates. The An. gambiae M form occurred in very low numbers and could not be assessed reliably for resistance. The standard PCR assay for detection of the kdr mutation in An. gambiae S form showed little association with pyrethroid resistance. Subsequent sequencing of the II56 domain containing the kdr mutation from nine surviving mosquitoes showed that eight were homozygous resistant and one heterozygous. This correlated with the bioassay results and with previous studies on West African An. gambiae, but raised concerns about the reliability of the PCR assay for detection of the kdr mutation. As a result of these investigations AngloGold/Ashanti are implementing, in addition to treatment and case management, a vector control programme that includes insecticide resistance management by alternation of various classes of insecticides for house spraying, supply of ITNs, screening of houses and environmental management where appropriate, i.e. integrated vector management.

Orthodontic status and treatment need of 12-year-old children in South Africa using the Dental Aesthetic Index.

OBJECTIVE: The aim of this study was to determine the prevalence and severity of malocclusion and orthodontic treatment needs in a sample of 12-year-old South African school children using the Dental Aesthetic Index (DAI), and to assess the relationship between malocclusion and certain socio-demographic variables. METHODOLOGY: The sample comprised 6142, 12-year-old children attending school in seven of the nine provinces of South Africa. For each subject the standard demographic information such as gender, population group, location type and employment status of the parents was collected, after which an intra-oral examination for occlusal status using the DAI was performed. Before the survey, the examiners were calibrated and trained and only examiners with an agreement score greater or equal to 80 per cent were included in the final study. RESULTS: The results showed that 47.7 per cent of the children in the sample presented with good occlusion or minor malocclusion, just over 52.3 per cent presented with identifiable malocclusion, a DAI score larger than 26. Of these, 21.2 per cent had definite malocclusion, 14.1 per cent had severe malocclusion and 16.9 per cent had very severe or handicapping malocclusion. Malocclusion as defined in this study was found to be significantly associated with the different population groups in South Africa, with gender and with dentition stage, but not with the location type or the employment status of parents. CONCLUSIONS: The results of this study show a high prevalence of malocclusion in 12-year-old South African children. The findings provide reliable base-line data regarding the prevalence, distribution and severity of malocclusion as well as useful epidemiological data on the orthodontic treatment needs of 12-year-old children in South Africa.

Uncovering the first double brimmed hat-shaped ascospores in Ambrosiozyma platypodis Van der Walt.

Using transmission electron microscopy with glutaraldehyde and osmium tetroxide as chemical fixatives, hat-shaped ascospores with two brims each were uncovered in the yeast Ambrosiozyma platypodis. This is the first report on such structures.

Caries status and treatment needs in South Africa: report of the 1999-2002 National Children's Oral Health Survey.

A third national children's oral health survey was conducted in South Africa between July 1999 and June 2002. OBJECTIVE AND METHODOLOGY: One of the objectives of the survey was to determine the prevalence and severity of dental caries and the treatment needs for dental caries in 4- to 5-, 6-, 12- and 15-year-old South African school children. The sample comprised 30876 children from the nine provinces of South Africa. RESULTS: The results of the survey show that 39.7 per cent of the 6-year-old group were caries free. This figure, 39.7 per cent, is below the goal of 50 per cent set by the Department of Health for 6-year-old children in South Africa for the year 2000. The DMFT of 1.1 for the 12-year-old group on the other hand was below the goal of 1.5 set for South Africa for the year 2000. The highest DMFT/dmft scores were recorded in the Western Cape Province and the lowest in the Limpopo Province. More than 80 per cent of caries in children go untreated while the greatest need for treatment in South African school children was for preventive services, restorations and extractions. The results for the 12-year-old-group show a reduction in dental caries severity in the permanent dentition in that the DMFT decreased from 2.5 in 1982 to 1.1 for the current survey. CONCLUSIONS: Although dental caries severity in South Africa is classified as low by WHO standards, the high levels of untreated caries in all age groups in South Africa is a cause for concern.

Variation in functional ascospore parts in the ascomycetous yeast Dipodascopsis uninucleata.

A variation in functional ascospore morphology was detected using electron microscopy (EM) in two varieties of the yeast Dipodascopsis uninucleata, i.e., D. uninucleata var. uninucleata and D. uninucleata var. wickerhamii. It was found that the latter produces ascospores characterized by the absence of small surface hooks which have been implicated in the release and re-assembly of ascospores in D. uninucleata var. uninucleata. These varieties are closely related on the basis of their mode of sexual reproduction, ascospore morphology as observed under the light microscope, physiological characteristics as well as the extent of divergence in the variable D1/D2 domain of the large subunit 26S ribosomal DNA.

Mapping 3-hydroxy oxylipins on ascospores of Eremothecium sinecaudum.

3-Hydroxy oxylipins were uncovered on ascospores of Eremothecium sinecaudum using immunofluorescence microscopy. This was confirmed by gas chromatography mass spectrometry. These oxylipins were observed only on ascospore parts characterised by nano-scale surface ornamentations simulating a corkscrew as demonstrated by scanning electron microscopy. Conventional ascospore staining further confirms its hydrophobic nature. Using confocal laser scanning microscopy we found that the corkscrew part with spiky tip of needle-shaped ascospores may play a role in rupturing the ascus in order to affect its release. Through oxylipin inhibition studies we hypothesise a possible role for 3-hydroxy oxylipins in facilitating the rupturing process.

Oxylipins and ascospore morphology in the ascomycetous yeast genus Dipodascus.

Immunofluorescence microscopy was used to assess members of the yeast genus Dipodascus for the presence of 3-hydroxy oxylipins. Fluorescence was associated with the aggregating ascospores in all species tested, thus suggesting the association of 3-hydroxy oxylipins with these cells, especially the surrounding slime sheaths. An ultrastructural study of the ascospores revealed sheaths with indentations, probably caused by the close packing of the ascospores to form clusters. In addition, an increase in the neutral and glycolipid fractions as well as a decrease in the phospholipid fraction during ascosporogenesis in D. ambrosiae was found.

First Report of Ascochyta spp. on Soybean in South Africa.

During February 2000 soybean fields over a wide area in South Africa were affected by a previously unreported disease. A typical target spot developed on leaves and many became blighted. Elongated dark brown to black lesions developed on the stems, often resulting in wilting of young shoots. Petioles and leaf axils were colonized, resulting in premature leaf drop. The most severe manifestation was on pedicels where infection suppressed podfill and plants remained green as ripening was delayed. Two distinct groups of isolates were obtained from lesions. In both groups an Ascochyta anamorph was present, while from some lesions collected in Kwazulu-Natal and Mpumalanga, a teliomorph (Mycosphaerella) was also present. Since dry beans are produced in these areas and M. phaseolorum is common on this crop, it was believed that the pathogen might have moved to soybean. In cross inoculations, both soybean and dry bean isolates were pathogenic to both hosts. However, M. phaseolorum isolates were more aggressive to both hosts than the Ascochyta sp. Morphologically the anamorphs of two types of isolates were indistinguishable. DNA was isolated from freeze dried mycelia using a modified version of the CTAB-method described by Graham et al. (1). The DNA concentration and purity were estimated by measuring absorbances at A260 and A280. Genetic difference between both isolates were determined using amplified fragment length polymorphism (AFLP) technique. The AFLP analysis was performed following the protocol described by Vos et al. (2) and the product manual supplied by Life Technologies Inc. (Gaithersburg, MD) with minor modifications. Five randomly selected primer pair combinations were tested for their ability to reveal polymorphisms between the isolates. The gel electrophoresis for AFLP products was as described by Vos et al. (2). AFLP gels were silver stained following the protocol described by silver sequence DNA sequencing system manual (Promega, Madison, WI). All five primer pairs revealed only polymorphisms between isolates. No corresponding bands between the two isolates were detected using these five primer pair combinations. It is concluded that both M. phaseolorum and an unidentified Ascochyta sp. were the cause of the epidemic. Ascochyta spp. have not previously been reported on soybean in South Africa. References: (1) G. C. Graham et al. Biotechniques 16:48-50, 1994. (2) P. Vos et al. Nucleic Acids Res. 21:4407-4414, 1995.