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Biomedical subjects

H T Groeneveld

Publications and source records attributed to H T Groeneveld.

At least 37 records · Page 2Linked to original sources
PubMed1992

Comparative morphology of the mandibulodental complex in wild and domestic canids.

The relationships between mandibular and dental measurements were investigated in a sample of 60 adult domestic dogs, 17 black-backed jackals Canis mesomelas, 18 side-striped jackals C. adustus and 16 Cape foxes Vulpes chama. Standard mesiodistal and buccolingual tooth measurements, together with 8 mandibular measurements (intercondylar distance, intercarnassial breadth, mandibular length, arch length, condylar height, canine-condylar length, mandibular width, mandibular height) were scaled allometrically to total skull length. Despite wide differences in diet and sexual dimorphism between the 3 wild canid species, larger canids were found to be scaled up versions of smaller canids. While males showed a highly concordant patterning when compared with domestic dogs of equivalent size, females showed a remarkably mosaic pattern. Relative to skull size, the only teeth that appear to be larger than those of equivalently sized domestic dogs were the second molars. It is suggested that those theories of sexual dimorphism and functional integration which apply to skeletodental dimensions in primates may not be applicable to canids.

Animals↗
PubMed1992

High-dimensional plots in the evaluation of interpopulation differences in human tooth size.

The use of high-dimensional plots is explored in the evaluation of interpopulation differences in tooth size. Buccolingual and mesiodistal diameters were determined on the teeth of 202 Paraguayan Lengua Indians, 100 skeletal Blacks, 206 living South African Blacks and 125 living South African caucasoids. Multivariate discrimination between the four populations was effected by means of canonical variate analyses and stepwise discriminant analyses. These results were then compared to Andrews plots generated for males and females in each of these populations. Our results show that Blacks and caucasoids have significantly differing curves and that Amerindians share characteristics of both these groups.

Analysis of Variance↗
PubMed1991

Tooth size and the Carabelli trait.

The Carabelli trait and its association with maxillary molar crown base and cusp size was studied in a group of 128 Kwengo, a San-Negro hybrid community living in Western Caprivi, Namibia. The trait was classified according to a modification of the scheme put forward by Dahlberg and by Scott (In: Dental Anthropology, New York: Pergamon, 1963) (Hum. Biol. 52:63-78, 1980). Crown base areas were larger in trait-positive than in trait-negative molars, and this difference existed for all eight categories of the trait in the first molar and for most of the categories in the second and third molars. The degree of expressivity of the trait seems to be associated with molar size, but this is more apparent in the first than in the second and third molars.

Adult↗
PubMed1991

Productivity of pure- and crossbred cattle in a subtropical environment.

The influence of different breeds of sire and dam types on cow productivity in an arid, subtropical environment was studied. Cows with calves sired by Simmentaler, Hereford and Bonsmara bulls were more (P less than 0.05) productive than those with calves sired by Afrikaner bulls. Simmentaler sires were superior (P less than 0.05) to Bonsmara sires. Crossbred cows of predominant (greater than 50%) Bos taurus breeding were generally superior to crossbreds of predominant B. indicus breeding and purebreds. Crossbreeding systems to utilize breed effects to optimise cow productivity within environmental constraints are discussed.

Animals↗
PubMed1991

Effects of time of day, season and stratum on Haemonchus contortus and Haemonchus placei third-stage larvae on irrigated pasture.

The effect of time of day, season and stratum of herbage and soil on the availability of Haemonchus contortus and Haemonchus placei third-stage larvae (L3) on pasture was assessed. Feces from infected calves and lambs were placed on pasture plots and samples of upper herbage, lower herbage, mat and soil were collected at five intervals per day throughout the daylight hours on 18 sample days over 12 months. Using recovery rate factors derived from a preliminary investigation on the efficacy of larval recovery from each stratum, the data on larval recoveries were analyzed for the effect of season, time and stratum, and their interactions. Significant (P less than 0.05) differences were found for season, stratum and the season-with-stratum interaction for both parasites. No significant differences were detected for larval counts at different times of the day. Larval recoveries of H. contortus were larger throughout the study than those of H. placei. Most H. contortus L3 were recovered in the summer and autumn, and H. placei in the spring and summer. For both parasites, the recoveries of larvae from the upper and lower herbage were larger than those from the mat and soil. The implications of these findings are discussed in terms of control strategies.

Animals↗
PubMed1991

An allometric perspective on primate postcanine tooth size.

The allometric relations of postcanine tooth size were evaluated in a sample of 66 adult Galago crassicaudatus (34 males, 32 females). Postcanine tooth area and length (estimated from mesiodistal and buccolingual measurements of upper and lower cheek teeth) were scaled to 4 cranial measures: bimaxillary width, maxillo-alveolar length, mandibular length and bigonial width. Postcanine tooth size was also scaled to body weight, body length and total skull length. It was found that postcanine surface and length were significantly correlated to the cranial measures employed in females, showing positive allometric scaling. These correlations were, however, lacking in males. In neither sex was postcanine size found to be significantly correlated to body length or weight.

Animals↗
PubMed1991

[Evaluation of Tenoxicam for control of postoperative pain and swelling following surgical removal of impacted molars].

This study reports on the efficacy of a single preoperative administration of Tenoxicam (20 mg intramuscular) after removal of two or more impacted molars. The recording of postoperative pain and swelling on a categorical and linear scale showed that there were no significant differences between the experimental and control groups. However, a significant reduction in pain was noted on the first postoperative day. We concluded that a single dose of Tenoxicam administered one hour preoperatively did have a significant analgesic effect, even though there was no significant reduction in postoperative swelling. Patients who did not have the injection had a 5.37 greater change of having more postoperative pain than those who were injected with Tenoxicam.

Adolescent↗
PubMed1991

Overberg research projects. X. Faecal egg counts in the interpretation of nematode worm burdens in sheep.

Worm egg counts were compared with nematode worm burdens from data collected from greater than 400 sheep killed in experiments on the epidemiology of nematode parasites in the Overberg, in the winter rainfall area of the southern Cape Province. Data were analysed in several ways but no method could be found to accurately estimate the number of nematodes present from the faecal egg count in respect of individual sheep. However, the mean natural log egg count (epg) can roughly predict the mean natural log nematode count in groups of sheep.

Animals↗
PubMed1991

The safety of dimetridazole alone and in conjunction with oxytetracycline in Hereford crossbred steers.

Dimetridazole was given intraruminally alone, and in conjunction with oxytetracycline to healthy, 10-11 month-old Hereford cross-bred steers (n = 6). Intraruminal treatment with dimetridazole was given through a fistula at 75 mg kg-1 daily for 5 d, while the oxytetracycline was injected intramuscularly at 10 mg kg-1 on Days 1 and 3 of the dimetridazole treatment. The animals were observed at various intervals throughout the trial period for adverse reactions, including effects on ruminal activity and motility, changes in live-mass, venous acid-base balance, haematology and ruminal and serum ammonia concentrations. Dimetridazole, either when used alone or in conjunction with oxytetracycline, had a marked effect on ruminal function. Within 6 h of dosing, the ruminal pH fell to below 5, but then returned to pretreatment values over the next 24-48 h. This was followed by the eradication of the ruminal protozoal population in all animals tested and an increase in the methylene blue reduction time to more than 6 min. Ruminal motility remained unaffected throughout this period. During the week of treatment, the mean live-mass of the animals dropped by 20 +/- 9.9 kg in the dimetridazole treated group and by 13.3 +/- 2.8 kg in the animals treated with both dimetridazole and oxytetracycline. A mild to severe watery diarrhoea, which continued for 1 to 2 d, occurred in 4 animals after the first dimetridazole treatment. A compensated metabolic acidosis and an increase in haematocrit were observed. An initial transient rapid rise in rumen ammonia concentrations did not result in a concurrent rise in serum ammonia concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The reliability of human odontometric data.

The present analysis addressed the reliability of human dental mensuration, with special reference to intra- and inter-observer error, the effect of time and of tooth type. Two observers were asked to measure the same 35 incisors, premolars and molars, using the same mensurational technique and the same instrumentation. Standard mesiodistal (MD) and buccolingual (BL) measurements were repeated on the next day and after six months. Measurement error was evaluated by means of Pearsonian correlation coefficients, mean absolute error, the Bland-Altman procedure, percentage error and an analysis of variance. It was concluded that human dental mensuration is subject to a large error component which is more marked in the MD than in the BL dimension, higher in the anterior than the postcanine teeth and greater between than within observers. These error components were shown to be random rather than systematic.

Analysis of Variance↗
PubMed1990

Nonrandom association of genetic markers in a sample of South African blacks.

According to classical genetic theory, allelic genes at one locus are expected to segregate and be manifested independently of allelic genes at another locus. At the population level any significant deviation from this general hypothesis resulting from specific biologic and genetic effects can be recognized in the form of nonrandom associations between genetic markers. The present data, consisting of 24 genetic polymorphisms determined from a sample of 998 unselected and unrelated South African blacks, offers an opportunity to test whether or not any such nonrandom associations exist between the genetic markers. After appropriate statistical calculations on the population data, we found that 13 pairs of genetic polymorphisms demonstrate a nonrandom association (statistically significant). Because the results cannot be explained in terms of known biologic mechanisms, we conclude that the associations observed could be due to random statistical effects (repeated application of the chi-square test) and/or to real (as yet unknown) biologic phenomena in the population studied. This tentative conclusion can serve as a guideline for more specific investigations.

Black People↗
PubMed1990

Evaluation of the efficacy of anthelmintics against parafilariosis in cattle.

Parafilariosis was first described in South Africa in 1964, thereafter being discovered at numerous localities in the country. When it became obvious that Parafilaria bovicola, for which no treatment was known, caused considerable economic losses, trials involving a series of compounds were conducted to identify candidate remedies. This paper describes an anthelmintic test for evaluating the efficacy of compounds for registration for field use. Recovery of Parafilaria worms is impractical for anthelmintic testing, and consequently the lesion sizes of treated and control groups of cattle are compared statistically, using appropriate statistical tests. The seasonal incidence of mature worm infection in cattle in South Africa is such that trials should commence after June and be completed before the end of January, allowing a lapse of 70 days between treatment and slaughter for resolution of the lesions. The presently available parafilaricidal compounds while of value for treating slaughter stock, when used alone will probably not be effective for control of infection in the field.

Animals↗
PubMed1989

Allocation and discrimination based on human odontometric data.

This study contrasts the confidence with which individuals may be grouped and then re-allocated on the basis of odontometric data. These data are derived from the mesiodistal and buccolingual diameters of 202 Lengua Indians of Paraguay (100 males, 102 females), 125 Caucasoid schoolchildren (59 male, 66 female), and 206 Negroes (106 male, 100 female). Multivariate intergroup discrimination is effected by means of canonical and stepwise discriminant analysis, whilst allocation is evaluated by means of posterior and typicality probabilities. Bias is reduced by means of a jackknifing procedure. High levels of discriminatory confidence (each Wilk's Lambda, P less than 0.01) are matched by high percentage correct classification (Caucasoid, 67.4-75.0%; Negro, 71.0-77.3%; Amerindian, 65.2-78.1%). However, these results are not matched by allocatory procedures: only 21.7% of caucasoids, 21.4% of Negroes, and 28.8% of Amerindians could be re-allocated with probabilities in excess of 80%. It is concluded that while multivariate discriminant techniques may be usefully employed in the separation of different populations, individuals may not be assigned with the same degree of confidence, even with an a priori knowledge of their group membership.

Analysis of Variance↗
PubMed1989

Alpha-L-fucosidase as a serum marker of hepatocellular carcinoma in southern African blacks.

The purpose of this study was to compare alpha-L-fucosidase and alpha-fetoprotein as serum markers of hepatocellular carcinoma in 72 southern African blacks with this tumour and 64 matched patients with benign hepatic diseases which might be mistaken clinically for hepatocellular carcinoma. Alpha-L-fucosidase activity was assayed using p-nitrophenyl-L-fucopyranoside (pNpf) as a substrate and alpha-fetoprotein concentrations were measured by radioimmunoassay. Serum alpha-L-fucosidase activity in the patients with hepatocellular carcinoma (mean 1,268, s.e.m. +/- 83.7, median 1,150 and range 38-3,698 nmol pNpf ml-1 h-1) was significantly higher than that in the matched controls (mean 798, s.e.m. +/- 65.8, median 648 and range 273-3,825 nmol pNpf ml-1 h-1) (P = 0.0001). However, alpha-L-fucosidase was both less sensitive (75 versus 87%) and less specific (70 versus 87%) than alpha-fetoprotein as a serum marker of hepatocellular carcinoma. When, in an endeavour to eliminate false-positive results, the diagnostic cut-off level for alpha-L-fucosidase was increased to 1,500 nmol pNpf ml-1 h-1 and for alpha-fetoprotein to 400 ng ml-1, the sensitivity of alpha-L-fucosidase fell to 21% whereas that of alpha-fetoprotein remained satisfactory at 78%. If the two markers were used together, the number of false-negative alpha-fetoprotein results was reduced from 13 to 5.5%. We conclude that alpha-L-fucosidase is less useful than alpha-fetoprotein as a single marker of hepatocellular carcinoma in southern African blacks. However, the two markers can profitably be used together.

Africa, Southern↗
PubMed1989

Physiological and blood biochemical responses to submaximal treadmill exercise in Canaan dogs before, during and after training.

Physiological haematological and blood biochemical parameters were studied in Canaan dogs (n = 8) as possible indices of fitness. These parameters were then used to distinguish between fit and unfit dogs and to monitor the changes in these parameters during training and detraining periods. Fitness was defined as the ability to run for one hour on a motorised treadmill (speed 8.65 km h-1, inclination 10 degrees) while maintaining rectal temperature and heart rate below 41 degrees C and 250 beats min-1 respectively. Fit dogs showed consistently lower values of heart rate and rectal temperature during exercise and recovery, and significantly lower increases for post exercise plasma creatine kinase activity and plasma lactate concentration. Significantly higher values for haemoglobin concentration were found immediately post exercise. There were no significant differences between fit and unfit dogs for post exercise plasma concentrations of aspartate aminotransferase, white blood cell count or total protein, although the unfit dogs showed a tendency towards higher values. Similarly, unfit dogs tended to have lower values for plasma glucose concentration, haematocrit and red cell count. Values for heart rate and rectal temperature during exercise differed significantly between various dogs until numbers fell, due to the inability of certain dogs to complete the exercise test. Dogs were consistent according to whether their values lay above or below the mean value for all dogs. These differences disappeared after 8 weeks of training. Fitness deteriorated after 3 to 5 weeks of detraining. According to these results, heart rate and rectal temperature appear to be the most suitable and sensitive indicators of fitness in tracking dogs. The haematological and blood biochemical parameters tested were found to be of limited use. It is suggested that apparent inherent superiority of dogs should be accounted for in prospective breeding programmes.

Animals↗
PubMed1988

Allometric relations of teeth and jaws in man.

Static adult intraspecific allometry of jaws and teeth was investigated in a sample of 100 Negro crania. The relations between tooth area, postcanine surface, incisor surface, and four viscerocranial measures were examined separately for males and females. Our results indicate a marked lack of morphological integration between P-sets within the orofacial subregion and a similar lack of correspondence between jaw size and tooth size. Allometric analyses indicate that mandibular length scales negatively allometric to maxilloalveolar length and to bigonial width, that canine base area scales positively to upper and lower jaw length, and that all the other teeth scale negatively to jaw length. The postcanine surface area was found to be negatively allometric to the canine base area, which in turn scaled isometrically to incisor surface. Hence, any lengthening of the mandible will tend to be associated with a relative shortening of the maxilla, with relatively larger canines and a relative reduction of the cheek teeth.

Black People↗
PubMed1988

Exposure-response relationship for a dichotomized response when the continuous underlying variable is not measured.

Radiological assessment of pneumoconiosis is an example of a dichotomized variable, namely one that is analysed as a binary response but in fact has an underlying continuum, which in this case is not measurable. Estimates of exposure-response relationships vary greatly for different observers of a dichotomized response variable because of random error of measurement and differences in the threshold implicitly chosen by each observer for categorizing cases. We present a method of using the biserial correlation coefficient and normal distribution theory to estimate exposure-response relationships at any required threshold for each observer. Exposure-response relationships can also be corrected for random observational error using the reliability coefficient, calculated as the tetrachoric correlation between repeat observations by readers.

Asbestosis↗