The veterinary profession and its place in the scientific development of South Africa     

D G Steyn 《Journal of the South African Veterinary Medical Association》1971,42(2):103-109

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Prevalence and determinants of stunting and overweight in 3-year-old black South African children residing in the Central Region of Limpopo Province, South Africa     

Mamabolo RL  Alberts M  Steyn NP  Delemarre-van de Waal HA  Levitt NS 《Public health nutrition》2005,8(5):501-508

OBJECTIVES: To determine the prevalence of stunting, wasting and overweight and their determinants in 3-year-old children in the Central Region of Limpopo Province, South Africa. DESIGN: Prospective cohort study. SETTING: Rural villages in the Central Region of the Limpopo Province, South Africa. SUBJECTS: One hundred and sixty-two children who were followed from birth were included in the study. Anthropometric measurements and sociodemographic characteristics of the children were recorded. RESULTS: Height-for-age Z-scores were low, with a high prevalence of stunting (48%). The children also exhibited a high prevalence of overweight (22%) and obesity (24%). Thirty-one (19%) children were both stunted and overweight. Gaining more weight within the first year of life increased the risk of being overweight at 3 years by 2.39 times (95% confidence interval (CI) 1.96-4.18) while having a greater length at 1 year was protective against stunting (odds ratio (OR) 0.41; 95% CI 0.17-0.97). Having a mother as a student increased the risk for stunting at 3 years by 18.21 times (95% CI 9.46-34.74) while having a working mother increased the risk for overweight by 17.87 times (95% CI 8.24-38.78). All these factors also appeared as risks or as being protective in children who were both overweight and stunted, as did living in a household having nine or more persons (OR 5.72; 95% CI 2.7-12.10). CONCLUSION: The results of this study highlight the importance of evaluating anthropometric status in terms of both stunting and overweight. Furthermore, it is important to realise the importance of normal length and weight being attained at 1 year of age, since these in turn predict nutritional status at 3 years of age.  相似文献   

Effect of Long-Term in Vitro Sub-culturing on Quality Degeneration of Sweet Potato Varieties： Morpho- Anatomic Assessment and Simple Sequence Repeats Analysis     

Mihiretu Cherinet Hundayehu  ;Elsa Du Toit  ;Sunette Laurie  ;Martin Steyn  ;Ria Greyling  ;Nokuthula Myeza 《农业科学与技术》2014,(10):811-821

The aim of this study was to assess the effect of long-term in vitro sub-culturing on the varietal degeneration of three sweet potato varieties, namely, Monate, Mokone and Ndou which were sub-cultured for 32, 23 and 12 generations, respectively. Each generation was cultured in a media which is made from 4.43 g/L Murashige and Skoog （MS）, 30 g/L sucrose and 2 g/L gelrite, respectively, and grown under 16 h light and 8 h dark photoperiod for 30 d. For each generation, 45 plantlets were acclimatized for two months in a glasshouse. Data on in vitro growth performance and 11 morphological characteristics during acclimatization were recorded. Early root and shoot formation was observed after the 27th and 21st sub-cultured generations of Monate and Mokone, respectively. During acclimatization, plantlets from the same variety showed differences in morphological traits such as leaf colour, abaxial leaf pigmentation, vine pigmentation, petiole pigmentation, leaf wrinkling and flowering. However, the rate of these morphological differences is random and irrespective to increase in sub-culturing. Therefore, to understand the genetic base of these morphological variability, two plantlets from each variety were subjected to genetic analysis by using five simple sequence repeat （SSR） primers （IB-242, IB-318, IB-255F, 1B-248 and IB-255）. Although SSR loci IB-255F and IB-318 could distinguish between the three varieties, there were no allelic polymorphisms detected in plantlets from the same varieties. Therefore, long-term sub-culturing do not leads to quality degeneration in the three sweet potato varieties.  相似文献   

Overweight among children decreased, but obesity prevalence remained high among women in South Africa, 1999-2005     

Kruger HS  Steyn NP  Swart EC  Maunder EM  Nel JH  Moeng L  Labadarios D 《Public health nutrition》2012,15(4):594-599

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Effects of Prolonged in vitro Culture and Cryopreservation on Viability,DNA Fragmentation,Chromosome Stability and Ultrastructure of Bovine Cells from Amniotic Fluid and Umbilical Cord     

ER da Cunha  CF Martins  CG Silva  HC Bessler  SN Báo 《Reproduction in domestic animals》2014,49(5):806-812

The objective of this work was to study cellular types that did not participated in the gastrulation process, amniotic fluid cells (AFCs) and umbilical cord cells (UCCs), in conditions of long‐term culture and cryopreserved with different solutions. The AFCs and UCCs were used in a comparative study with ear fibroblast cells (EFCs) that were cultured in vitro until 20 cellular passages and cryopreserved in 10% dimethylsulphoxide (DMSO), 5% dimethyl formamide (DMF) and 7% glycerol (Gly) solutions. The cellular viability, ultrastructure, DNA fragmentation and chromosome stability were evaluated to determine the cellular type most resistant. In all cell types, it was possible to evaluate the AFCs until 15 passages and UCCs until 20 passages with different periods of cellular growth to reach the confluence phase. Solutions containing 10% DMSO ensured viability of 90.33 ± 5.58%, 90.56 ± 4.40% and 81.90 ± 3.31%, respectively for EFCs, AFCs and UCCs, being significantly more efficient and with less variation than other cryoprotectant solutions. The AFCs were more sensitive to cryopreservation and presented low viability rate at the passage 20 (17.2 ± 8.87%). There was no change in karyotype and nuclear fragmentation was low in all cellular passages studied. With the scanning electron analysis was possible the characterization of AFCs and UCCs in suspension. The three cellular types of cells presented different shapes and characteristics on the surface. The results demonstrate that bovine AFCs and UCCs can be isolated, cultured in vitro and cryopreserved in 10% DMSO, not causing damage to DNA and chromosomes. The UCCs were more resistant than AFCs in all aspects.  相似文献   

Stability and partitioning of closantel and rafoxanide in ruminal fluid of sheep     

Swan GE  Oliver DW  Van Rensburg J  Steyn HS  Mülders MS 《The Onderstepoort journal of veterinary research》2000,67(2):97-103

The stability and the partitioning of closantel and rafoxanide in ruminal fluid (RF) was examined in vitro. Stability was evaluated in two studies in a ruminal fluid-artificial saliva (RF-AS) mixture containing either drug. Drug concentrations were measured in samples collected sequentially from four batches of RF-AS fortified with either closantel or rafoxanide in one study and in four separately incubated aliquots of a RF-AS mixture of each drug in the second study at the start and at various intervals during a 24 h incubation period. The viability of the in vitro RF-AS incubation model was validated by the presence of digoxin degradation (T1/2 of 39,1 +/- 13 h) and by the absence of significant time related differences (P> 0,5) in volume of gas produced, pH and methylene blue reduction time of the RF-AS drug mixture. Partitioning of closantel and rafoxanide was determined by measuring the relative drug concentration of the fluid and particulate phases in RF fortified with either drug at different concentrations. Closantel and rafoxanide were shown to be stable in a RF-AS mixture and were not subjected to any significant biodegradation. An initial marked reduction in drug concentration measured in the RF-AS mixture during the first 2 h of incubation was attributed to the attachment of both drugs onto particulate matter. This was subsequently confirmed in the partitioning study. More than 80% of closantel and rafoxanide was shown to be associated with the particulate phase of RF  相似文献   

Otto Abbot     

HC White 《Australian veterinary journal》1998,76(5):367-367

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Intravascular plasma disposition and salivary secretion of closantel and rafoxanide in sheep     

Swan GE  Koeleman HA  Steyn HS  Mülders MS 《Journal of the South African Veterinary Association》1999,70(2):75-79

The plasma and salivary disposition of closantel and rafoxanide were examined following intravenous administration in adult sheep. Two studies were conducted with rafoxanide at 7.5 mg/kg and 1 with closantel using 2 doses (5 and 15 mg/kg). The pharmacokinetic profile of both drugs in plasma were best described by a 2-compartmental model with 1st-order rate constants. Plasma disposition of closantel and rafoxanide were characterised by a rapid distribution (t1/2(alpha)) of <30 min), long elimination half-life (t1/2(beta)) of 17.0 +/- 4.0 days for closantel and 7.2 +/- 0.6 days for rafoxanide), small apparent volume of distribution (V(SS) of <0.15 l/kg) and a slow rate of total body clearance (Cl of <0.01 ml/min/kg). The area under the drug plasma concentration curve (AUC) of closantel at 5 mg/kg was nearly twice as large as that of rafoxanide at 7.5 mg/kg resulting from the slower t1/2(beta) observed with closantel compared to rafoxanide. Large individual differences were observed in the rate measurements of distribution (k12, k21 and t1/2(alpha)), whereas the parameters of elimination (k10, t1/2(beta) and Cl), were more consistent between animals. A dose proportional increase in AUC was observed for closantel administered at 5 and 15 mg/kg. A low, constant salivary concentration of closantel (mean of 0.04 +/- 0.05 microg/mL) and rafoxanide (mean of 0.07 +/- 0.04 microg/mL) was observed during the 24-h examination period after dosing.  相似文献   

Forecasting Yield and Tuber Size of Processing Potatoes in South Africa Using the LINTUL-Potato-DSS Model     

A. T. B. Machakaire  J. M. Steyn  D. O. Caldiz  A. J. Haverkort 《Potato Research》2016,59(3):195-206

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The formation of chondrules: petrologic tests of the shock wave model     

Connolly Jr HC  SG Love 《Science (New York, N.Y.)》1998,280(5360):62-67

Chondrules are millimeter-sized rounded igneous rocks within chondritic meteorites. Their textures and fractionated mineral chemistries suggest that they formed by repeated, localized, brief (minutes to hours) melting of cold aggregates of mineral dust in the protoplanetary nebula. Astrophysical models of chondrule formation have been unable to explain the petrologically diverse nature of chondrites. However, a nebular shock wave model for chondrule formation agrees with many of the observed petrologic and geochemical properties of chondrules and shows how particles within the nebula are sorted by size and how rims around chondrules are formed. It also explains the volatile-rich nature of chondrule rims and the chondrite matrix.  相似文献