<p>CHAID analysis of the 576 selected cases over 5 fatigue groups (colour code as in <a ... more <p>CHAID analysis of the 576 selected cases over 5 fatigue groups (colour code as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0216298#pone.0216298.g002" target="_blank">Fig 2</a>), incorporating the data from the biochemical and MSQ score analysis.</p
<p>Caffeine clearance (Intervention 1) progresses through CYP450-1A2, comprises only a phas... more <p>Caffeine clearance (Intervention 1) progresses through CYP450-1A2, comprises only a phase 1 process and is measured as the residual substrate in saliva, expressed as a percentage of caffeine recovery. The acetaminophen challenge involves three phase II conjugation reactions, evaluated through the products formed following biotransformation: (1) conjugation of glucuronic acid to the hydroxyl group of acetaminophen; (2) sulphation of the phenolic hydroxyl group of acetaminophen; and (3) glutathione conjugation of N-acetyl-p-benzoquinone imine, a phase 1 activated form of acetaminophen. In the simultaneous acetylsalicylic acid challenge, glycination of the functional carboxylic group is catalysed by glycine-N-acyl transferase (GLYAT). All the substances mentioned are measured in urine samples, analysed by HPLC, as indicated. The acetaminophen and salicylate ingestion detoxification are measured through the glucuronide, sulphate and mercapturate conjugates as well as for salicyluric acid, expressed as percentage recovery. Three derivatives of salicylate may likewise be observed in this challenge (2,3-DHBA, 2,5-DHBA and catechol) and are measured by a GC-MS method. Abbreviations: CYP450-1A2, -2E1 and -2CP: mixed function CYP450 oxidase system with isozymes as indicated; GLYAT: glycine-N-acetyltransferase; HPLC: high-pressure liquid chromatography; GC-MS: gas chromatography–mass spectrometry; GSH: glutathione; 2,3-DHBA: 2,3-dihydroxy benzoic acid: 2,5-DHBA: 2,5-dihydroxybenzoic acid.</p
<p>Indicated in the figure are: Patients with low fatigue (graphs to the left) relative to ... more <p>Indicated in the figure are: Patients with low fatigue (graphs to the left) relative to those with high fatigue (graphs to the right) in each panel. Values for all individual cases are shown as dots, whereas the squared area represents the 95% confidence interval (orange) and one standard deviation (blue) about the mean (red line). Fold change (FC) measures are indicated for the low relative to the high fatigue groups, and were determined from the original experimental data. The statistical and practical significance of differences (<i>p</i>-values and ES) were calculated from the transformed data. The respective p, ES and FC values shown in Fig 5 were calculated as mentioned above, but all data points in these figures represent the original experimental values.</p
Hygroscopic seeding was conducted in the sixties and early seventies in the USA, but since then, ... more Hygroscopic seeding was conducted in the sixties and early seventies in the USA, but since then, most cloud seeding efforts have used glaciogenic seeding materials, usually silver iodide and dry ice. Very little research has since been conducted on hygroscopic seeding in the USA and very few operational programs use hygroscopic materials. The reasons for this are the high amounts of seeding material needed and the usual corrosive character of these materials and the usual corrosive nature of these materials. Recently, an ongoing summertime convective cloud seeding research program in South Africa started using hygroscopic flares for seeding convective clouds for rainfall enhancement. After one season of randomized seeding highly significant results were obtained indicating that seeded clouds on average produce 100 ktons more water than unseeded clouds as derived from radar data. These results spurred intensive physical studies to determine the effect of the seeding material on the p...
<p>Indicated in the figure are: Patients with low fatigue (graphs to the left) relative to ... more <p>Indicated in the figure are: Patients with low fatigue (graphs to the left) relative to those with high fatigue (graphs to the right) in each panel. Values for all individual cases are shown as dots, whereas the squared area represents the 95% confidence interval (orange) and one standard deviation (blue) about the mean (red line). Fold change (FC) measures are indicated for the low relative to the high fatigue groups, and were determined from the original experimental data. The statistical and practical significance of differences (<i>p</i>-values and ES) were calculated from the transformed data. The respective p, ES and FC values shown in Fig 5 were calculated as mentioned above, but all data points in these figures represent the original experimental values.</p
<p>Selected studies on the association between biotransformation of xenobiotics and genetic... more <p>Selected studies on the association between biotransformation of xenobiotics and genetic polymorphisms in the <i>GLYAT</i> gene.</p
Back-carrying of children is a culturally accepted method of transport and safekeeping of babies ... more Back-carrying of children is a culturally accepted method of transport and safekeeping of babies in many cultures. Developmental consequences related to back-carrying practices have not been directly investigated. This study determined the relationship between frontal and transverse plane lower limb (LL) development, and back-carrying practices, in black Setswana-speaking children. In 691 2- to 9-year-old Setswana-speaking children, the tibiofemoral angle, intermalleolar distance, femoral anteversion angle (AVA) and tibial torsion angle (TTA), were measured to determine LL development. Back-carrying practices were recorded with a questionnaire and Classification and Regression Tree (CART) was used for the analyses. Significant (p < 0.001) relationships, between back-carrying practices and LL development, were discovered. Statistically significant greater genu valgum (F(5, 690) = 7.2, p < 0.001), greater internal TTAs (F(9, 684) = 17.8, p < 0.001), and smaller AVAs (F(13, 68...
Abstract This is the first study documenting the distribution and population biology of the Endan... more Abstract This is the first study documenting the distribution and population biology of the Endangered Aloe lettyae, an endemic to the highly threatened Woodbush Granite Grassland (WGG) in Limpopo Province, South Africa. We documented 19 A. lettyae populations and calculated the total area of occupied habitat at 17.5 ha within its extent of occurrence of 123 km2. Most populations were clustered on the south western side of the WGG, with all known localities less than 40 km apart in this severely fragmented vegetation type. Population size varied from 10 to 6547 plants, with ∼10,800 individuals estimated in total. Plant size and life history stage demographics were determined in seven of the 19 currently known A. lettyae populations, including two large populations, as well as a high- and a low-lying population, and constituted a representative sample of the entire geographical range of the species. For plant size, four metrics (number of leaves, number of leaf layers, height and diameter of the leaf rosette) were recorded for each sampled A. lettyae plant, and the presence of an inflorescence indicated its reproductive status. By means of the classification tree technique CHAID (Chi-square Automatic Interaction Detection), we determined that of the four plant size metrics, the ‘number of leaves’ predicts A. lettyae’s life history stages and fecundity most accurately, and revealed significant differences in the life history stage structure of the seven surveyed populations. Five populations occurring in relatively undisturbed WGG fragments, including the two large populations, comprised high proportions of adult individuals (77–89%), while only few A. lettyae juveniles were found (3–14%). By contrast, the relatively high percentage of juveniles (25–58%) and low percentage of adults (32–63%) observed in two small populations found in a degraded WGG fragment and in non-natural habitat respectively, appeared atypical. The percentage of subadults varied little across the surveyed populations (8–13%). In slow-growing, long-lived species such as A. lettyae, the dominance of adult individuals with a high probability of survival may be considered as indicative of stable populations. This study provides baseline A. lettyae population data for long-term demographic monitoring which will aid management and conservation of the range restricted, Endangered A. lettyae.
With over 3.5 decades dedicated exclusively to total joint replacement, our arthroplasty unit has... more With over 3.5 decades dedicated exclusively to total joint replacement, our arthroplasty unit has repeatedly identified and reported a clear correlation between cup wear on the one hand, and pain, interface widening and osteolytic failure on the other1. However, in view of the fact that this statement has sparked some controversy, clarification of this correlation became imperative, particularly in view of important clinical consequences. Materials and methods were provided by a potentially long-lasting gamma crosslinked cup. The arthroplasty follow-up ranged from 10-33 years. Objective clinical, radiographic and pathological evaluations were backed by computer analysis through the Department of Statistics at the University of Pretoria. We are able to conclude that the statistical correlation between wear, on the one hand, versus pain, interface effects and osteolysis on the other, was no coincidence but instead proved to be clearly conclusive. Of great importance is the fact that t...
The publication of our long-term hip replacement follow-up study computer analysis has clearly de... more The publication of our long-term hip replacement follow-up study computer analysis has clearly demonstrated the association between polyethylene (polyethylene/UHMWPE) wear on the one hand and pain, interface widening and osteolysis on the other. From a total of 97 cases, seven had true failure and needed ultimate revision. These seven cases formed the nucleus of the current study (Group 1). The course of events could then be analysed in great detail, and compared with the other 90 cases (Groups 2, 3, and 4). The purpose of this paper was to confirm the role of polyethylene wear (the independent variable) in the limitation of longevity of the implant; furthermore to identify the cut-off point of wear that is considered acceptable. At the same time quantification of P, I, O (pain, interface widening and osteolysis) was studied (the dependent variables). Once again, computer analysis provided us with detailed values that would constitute the cut-off points
South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde, Jan 24, 1975
The average dark adaptation time for newly recruited Black mineworkers is longer than that report... more The average dark adaptation time for newly recruited Black mineworkers is longer than that reported for Whites. While this longer dark adaptation time may result from a number of pathological conditions, its most likely cause is a deficiency of vitamin A in the diet. A study was conducted in which the vitamin A level of the blood and the dark adaptation times were correlated in a group of Black mineworkers upon arrival and again after 4 - 6 months continuous work underground in a gold mine. The study indicated that a very marked decrease occurred in the miners' serum vitamin A level between the time of arrival at the mine and the second examination. This difference was found to be highly significant. This decrease was accompanied by an increase in mean dark adaptation time, which was significant at the 5% level. These observations accord with the findings of a previous study and are indicative of an inadequate dietary intake of vitamin A during the period when the miners were on...
In this paper we produce a table of critical values of Mood's test statistic which may be use... more In this paper we produce a table of critical values of Mood's test statistic which may be used in the distribution-free comparison of the dispersions of two independent samples. As far as we know the main drawback in using this test statistic, developed more than 14 years ago, lies in the fact that its distribution has never been tabulated except for a few isolated cases. We also discuss a normal distribution approximation which may be used when the sample sizes fall outside the scope of our present table. A uniform correction for continuity cannot be suggested since Mood's statistic does not take on equi-spaced values. However, we do attempt such a correction. Our investigations indicate that this suggestion may not be worthwhile, especially for sample sizes the sum of which exceed about 30.
<p>CHAID analysis of the 576 selected cases over 5 fatigue groups (colour code as in <a ... more <p>CHAID analysis of the 576 selected cases over 5 fatigue groups (colour code as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0216298#pone.0216298.g002" target="_blank">Fig 2</a>), incorporating the data from the biochemical and MSQ score analysis.</p
<p>Caffeine clearance (Intervention 1) progresses through CYP450-1A2, comprises only a phas... more <p>Caffeine clearance (Intervention 1) progresses through CYP450-1A2, comprises only a phase 1 process and is measured as the residual substrate in saliva, expressed as a percentage of caffeine recovery. The acetaminophen challenge involves three phase II conjugation reactions, evaluated through the products formed following biotransformation: (1) conjugation of glucuronic acid to the hydroxyl group of acetaminophen; (2) sulphation of the phenolic hydroxyl group of acetaminophen; and (3) glutathione conjugation of N-acetyl-p-benzoquinone imine, a phase 1 activated form of acetaminophen. In the simultaneous acetylsalicylic acid challenge, glycination of the functional carboxylic group is catalysed by glycine-N-acyl transferase (GLYAT). All the substances mentioned are measured in urine samples, analysed by HPLC, as indicated. The acetaminophen and salicylate ingestion detoxification are measured through the glucuronide, sulphate and mercapturate conjugates as well as for salicyluric acid, expressed as percentage recovery. Three derivatives of salicylate may likewise be observed in this challenge (2,3-DHBA, 2,5-DHBA and catechol) and are measured by a GC-MS method. Abbreviations: CYP450-1A2, -2E1 and -2CP: mixed function CYP450 oxidase system with isozymes as indicated; GLYAT: glycine-N-acetyltransferase; HPLC: high-pressure liquid chromatography; GC-MS: gas chromatography–mass spectrometry; GSH: glutathione; 2,3-DHBA: 2,3-dihydroxy benzoic acid: 2,5-DHBA: 2,5-dihydroxybenzoic acid.</p
<p>Indicated in the figure are: Patients with low fatigue (graphs to the left) relative to ... more <p>Indicated in the figure are: Patients with low fatigue (graphs to the left) relative to those with high fatigue (graphs to the right) in each panel. Values for all individual cases are shown as dots, whereas the squared area represents the 95% confidence interval (orange) and one standard deviation (blue) about the mean (red line). Fold change (FC) measures are indicated for the low relative to the high fatigue groups, and were determined from the original experimental data. The statistical and practical significance of differences (<i>p</i>-values and ES) were calculated from the transformed data. The respective p, ES and FC values shown in Fig 5 were calculated as mentioned above, but all data points in these figures represent the original experimental values.</p
Hygroscopic seeding was conducted in the sixties and early seventies in the USA, but since then, ... more Hygroscopic seeding was conducted in the sixties and early seventies in the USA, but since then, most cloud seeding efforts have used glaciogenic seeding materials, usually silver iodide and dry ice. Very little research has since been conducted on hygroscopic seeding in the USA and very few operational programs use hygroscopic materials. The reasons for this are the high amounts of seeding material needed and the usual corrosive character of these materials and the usual corrosive nature of these materials. Recently, an ongoing summertime convective cloud seeding research program in South Africa started using hygroscopic flares for seeding convective clouds for rainfall enhancement. After one season of randomized seeding highly significant results were obtained indicating that seeded clouds on average produce 100 ktons more water than unseeded clouds as derived from radar data. These results spurred intensive physical studies to determine the effect of the seeding material on the p...
<p>Indicated in the figure are: Patients with low fatigue (graphs to the left) relative to ... more <p>Indicated in the figure are: Patients with low fatigue (graphs to the left) relative to those with high fatigue (graphs to the right) in each panel. Values for all individual cases are shown as dots, whereas the squared area represents the 95% confidence interval (orange) and one standard deviation (blue) about the mean (red line). Fold change (FC) measures are indicated for the low relative to the high fatigue groups, and were determined from the original experimental data. The statistical and practical significance of differences (<i>p</i>-values and ES) were calculated from the transformed data. The respective p, ES and FC values shown in Fig 5 were calculated as mentioned above, but all data points in these figures represent the original experimental values.</p
<p>Selected studies on the association between biotransformation of xenobiotics and genetic... more <p>Selected studies on the association between biotransformation of xenobiotics and genetic polymorphisms in the <i>GLYAT</i> gene.</p
Back-carrying of children is a culturally accepted method of transport and safekeeping of babies ... more Back-carrying of children is a culturally accepted method of transport and safekeeping of babies in many cultures. Developmental consequences related to back-carrying practices have not been directly investigated. This study determined the relationship between frontal and transverse plane lower limb (LL) development, and back-carrying practices, in black Setswana-speaking children. In 691 2- to 9-year-old Setswana-speaking children, the tibiofemoral angle, intermalleolar distance, femoral anteversion angle (AVA) and tibial torsion angle (TTA), were measured to determine LL development. Back-carrying practices were recorded with a questionnaire and Classification and Regression Tree (CART) was used for the analyses. Significant (p < 0.001) relationships, between back-carrying practices and LL development, were discovered. Statistically significant greater genu valgum (F(5, 690) = 7.2, p < 0.001), greater internal TTAs (F(9, 684) = 17.8, p < 0.001), and smaller AVAs (F(13, 68...
Abstract This is the first study documenting the distribution and population biology of the Endan... more Abstract This is the first study documenting the distribution and population biology of the Endangered Aloe lettyae, an endemic to the highly threatened Woodbush Granite Grassland (WGG) in Limpopo Province, South Africa. We documented 19 A. lettyae populations and calculated the total area of occupied habitat at 17.5 ha within its extent of occurrence of 123 km2. Most populations were clustered on the south western side of the WGG, with all known localities less than 40 km apart in this severely fragmented vegetation type. Population size varied from 10 to 6547 plants, with ∼10,800 individuals estimated in total. Plant size and life history stage demographics were determined in seven of the 19 currently known A. lettyae populations, including two large populations, as well as a high- and a low-lying population, and constituted a representative sample of the entire geographical range of the species. For plant size, four metrics (number of leaves, number of leaf layers, height and diameter of the leaf rosette) were recorded for each sampled A. lettyae plant, and the presence of an inflorescence indicated its reproductive status. By means of the classification tree technique CHAID (Chi-square Automatic Interaction Detection), we determined that of the four plant size metrics, the ‘number of leaves’ predicts A. lettyae’s life history stages and fecundity most accurately, and revealed significant differences in the life history stage structure of the seven surveyed populations. Five populations occurring in relatively undisturbed WGG fragments, including the two large populations, comprised high proportions of adult individuals (77–89%), while only few A. lettyae juveniles were found (3–14%). By contrast, the relatively high percentage of juveniles (25–58%) and low percentage of adults (32–63%) observed in two small populations found in a degraded WGG fragment and in non-natural habitat respectively, appeared atypical. The percentage of subadults varied little across the surveyed populations (8–13%). In slow-growing, long-lived species such as A. lettyae, the dominance of adult individuals with a high probability of survival may be considered as indicative of stable populations. This study provides baseline A. lettyae population data for long-term demographic monitoring which will aid management and conservation of the range restricted, Endangered A. lettyae.
With over 3.5 decades dedicated exclusively to total joint replacement, our arthroplasty unit has... more With over 3.5 decades dedicated exclusively to total joint replacement, our arthroplasty unit has repeatedly identified and reported a clear correlation between cup wear on the one hand, and pain, interface widening and osteolytic failure on the other1. However, in view of the fact that this statement has sparked some controversy, clarification of this correlation became imperative, particularly in view of important clinical consequences. Materials and methods were provided by a potentially long-lasting gamma crosslinked cup. The arthroplasty follow-up ranged from 10-33 years. Objective clinical, radiographic and pathological evaluations were backed by computer analysis through the Department of Statistics at the University of Pretoria. We are able to conclude that the statistical correlation between wear, on the one hand, versus pain, interface effects and osteolysis on the other, was no coincidence but instead proved to be clearly conclusive. Of great importance is the fact that t...
The publication of our long-term hip replacement follow-up study computer analysis has clearly de... more The publication of our long-term hip replacement follow-up study computer analysis has clearly demonstrated the association between polyethylene (polyethylene/UHMWPE) wear on the one hand and pain, interface widening and osteolysis on the other. From a total of 97 cases, seven had true failure and needed ultimate revision. These seven cases formed the nucleus of the current study (Group 1). The course of events could then be analysed in great detail, and compared with the other 90 cases (Groups 2, 3, and 4). The purpose of this paper was to confirm the role of polyethylene wear (the independent variable) in the limitation of longevity of the implant; furthermore to identify the cut-off point of wear that is considered acceptable. At the same time quantification of P, I, O (pain, interface widening and osteolysis) was studied (the dependent variables). Once again, computer analysis provided us with detailed values that would constitute the cut-off points
South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde, Jan 24, 1975
The average dark adaptation time for newly recruited Black mineworkers is longer than that report... more The average dark adaptation time for newly recruited Black mineworkers is longer than that reported for Whites. While this longer dark adaptation time may result from a number of pathological conditions, its most likely cause is a deficiency of vitamin A in the diet. A study was conducted in which the vitamin A level of the blood and the dark adaptation times were correlated in a group of Black mineworkers upon arrival and again after 4 - 6 months continuous work underground in a gold mine. The study indicated that a very marked decrease occurred in the miners' serum vitamin A level between the time of arrival at the mine and the second examination. This difference was found to be highly significant. This decrease was accompanied by an increase in mean dark adaptation time, which was significant at the 5% level. These observations accord with the findings of a previous study and are indicative of an inadequate dietary intake of vitamin A during the period when the miners were on...
In this paper we produce a table of critical values of Mood's test statistic which may be use... more In this paper we produce a table of critical values of Mood's test statistic which may be used in the distribution-free comparison of the dispersions of two independent samples. As far as we know the main drawback in using this test statistic, developed more than 14 years ago, lies in the fact that its distribution has never been tabulated except for a few isolated cases. We also discuss a normal distribution approximation which may be used when the sample sizes fall outside the scope of our present table. A uniform correction for continuity cannot be suggested since Mood's statistic does not take on equi-spaced values. However, we do attempt such a correction. Our investigations indicate that this suggestion may not be worthwhile, especially for sample sizes the sum of which exceed about 30.
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