Revisiting Nitrogen Fertilisation Rates of Kikuyu and Kikuyu-Ryegrass Pastures

Irrigated pastures are used for dairy production in South Africa. Minimum-tillage and nitrogen (N) fertilisation are important management practices for kikuyu (Pennisetum clandestinum) and ryegrass (Lolium spp.) pastures. Nitrogen fertiliser application rates as high as 500 kg N ha-1 year-1 have been reported. Conventional tillage as well as cutting and removal of herbage material (opposed to removal through grazing) are the basis on which these fertiliser guidelines were developed. The current management practices have substantially changed the soil organic carbon and N stoichiometry. The aim of this study was to determine an optimum rate of N application of kikuyu and kikuyu-ryegrass pastures. Five fixed N fertiliser rates (0, 20, 40, 60 and 80 kg N ha-1 grazing cycle-1) were evaluated. Soil characteristics and pasture performance were monitored over a two year period. Nitrate concentrations and total mineral soil N were substantial, compared to the control, when more than 40 kg N ha-1 grazing cycle-1 were applied, leading to potential losses to the environment. Differences in biomass production were mostly due to seasonal variation, while N treatment effects within a season were generally small. As N treatments increased on both the study sites, the self-sown clover component decreased. Agronomic nitrogen use efficiency was similar across treatments and seasons on both sites, with the exception of winter in the first year on the kikuyu-ryegrass site. The results indicate that the soil could be saturated with N, at least to a point where herbage production response is minimal. A positive response in terms of crude protein was observed in some of the higher N treatments, but up to a point where it was no longer favourable for milk production. It is therefore concluded that the current N guidelines needs to be revisited as they pose a risk to the environment and farm economics

International normalised ratio control in a non-metropolitan setting in Western Cape Province, South Africa

Background. The quality of international normalised ratio (INR) control determines the effectiveness and safety of warfarin therapy. Data on INR control in non-metropolitan settings of South Africa (SA) are sparse.Objectives. To examine the time in therapeutic range (TTR) and its potential predictors in a sample of Garden Route District Municipality primary healthcare clinics (PHCs).Methods. INR records from eight PHCs were reviewed. The TTR and percentage of patients with a TTR >65% were determined. A host of variables were analysed for association with TTR.Results. The median (interquartile range (IQR)) age of the cohort (N=191) was 56 (44 - 69) years. The median (IQR) TTR was 37.2% (20.2 - 58.8); only 17.8% of patients had a TTR ≥65%. Compared with patients aged >50 years, those aged <50 had worse INR control (median (IQR) TTR 26.6% (16.1 - 53.0) v. 43.5% (23.5 - 60.1); p=0.01). Patients hospitalised for any reason during the study period had worse INR control than patients not hospitalised (median (IQR) TTR 26.2% (16.2 - 50.2) v. 42.9% (23.5 - 62.0); p=0.02). On multivariable regression analysis, participants on warfarin for atrial fibrillation/flutter had better INR control than those with other indications for warfarin (odds ratio 2.21; 95% confidence interval 1.02 - 4.77; p=0.04), but the control was still very poor.Conclusions. INR control, as determined by TTR and proportion of TTR ≥65%, in these non-metropolitan clinics was poor. Age and hospitalisation as a marker of illness predicted poor control. There was a difference in control between groups, depending on the indication for warfarin. Evidence-based measures to improve the quality of INR control in patients on warfarin therapy need to be instituted as a matter of urgency

Hlapljivi organski spojevi u mlijeku dobivenom prirodnom fermentacijom i fermentacijom s pomoću pojedinačnih ili mješovitih kultura kvasaca i mliječno-kiselih bakterija

The volatile organic compounds present in 18 Zimbabwean naturally fermented milk (amasi) samples and those produced by various yeasts, lactic acid bacteria (LAB) and yeast/ LAB combinations were determined using headspace gas chromatography. The yeast strains used were: Candida kefyr 23, C. lipolytica 57, Saccharomyces cerevisiae 71, C. lusitaniae 68, C. tropicalis 78, C. lusitaniae 63, C. colliculosa 41, S. dairenensis 32, and Dekkera bruxellensis 43, and were coded Y1 to Y9, respectively. The LAB strains used were Lactococcus lactis subsp. lactis Lc39, L. lactis subsp. lactis Lc261, Lactobacillus paracasei Lb11, and L. lactis subsp. lactis biovar. diacetylactis C1, and were coded B1 to B4, respectively. Some of the volatile organic compounds found in amasi were acetaldehyde, ethanol, acetone, 2-methyl propanal, 2-methyl-1-propanol and 3-methyl-1-butanol. However, the levels of volatile organic compounds in the naturally fermented milk (NFM) samples varied from one sample to another, with acetaldehyde ranging from 0.1–18.4 ppm, 3-methyl butanal from <0.1–0.47 ppm and ethanol from 39.3–656 ppm. The LAB/C. kefyr 23 (B/Y1) co-cultures produced significantly (p<0.05) higher levels of acetaldehyde and ethanol than the levels found in the NFM. The acetaldehyde levels in the B/Y1 samples ranged from 26.7–87.7 ppm, with L. lactis subsp. lactis biovar. diacetylactis C1 (B4) producing the highest level of acetaldehyde in combination with C. kefyr 23 (Y1). Using principal component analysis (PCA), most of the NFM samples were grouped together with single and co-cultures of Lc261, Lb11 and the non-lactose fermenting yeasts, mainly because of the low levels of ethanol and similar levels of 3-methyl butanal. Chromatograms of amasi showed prominent peak of methyl aldehydes and their alcohols including 3-methyl-butanal and 3-methyl-butanol, suggesting that these compounds are important attributes of Zimbabwean naturally fermented milk.Hlapljivi organski proizvodi, u 18 uzoraka prirodno fermentiranog mlijeka iz Zimbabvea (amasi) i mlijeka dobivenog fermentacijom s pomoću kvasaca, mliječno-kiselih bakterija (LAB) i kombinacijom kvasaca i mliječno-kiselih bakterija određeni su plinskom kromatografijom na čvrstoj fazi. Upotrijebljeni su ovi sojevi kvasaca: Candida kefyr 23, C. lipolytica 57, Saccharomyces cerevisiae 71, C. lusitaniae 68, C. tropicalis 78, C. lusitaniae 63, C. colliculosa 41, S. dairenensis 32 i Dekkera bruxellensis 43, te su označeni s Y1 do Y9. Od LAB korišteni su sojevi Lactococcus lactis subsp. lactis Lc39, L. lactis subsp. lactis Lc261, Lactobacillus paracasei Lb11 i L. lactis subsp. lactis biovar. diacetylactis C1, označeni s B1 do B4. Acetaldehid, etanol, aceton, 2-metilpropanal, 2-metil-1-propanol i 3-metil-1-butanol su neki hlapljivi organskih spojevi pronađeni u prirodno fermentiranom mlijeku amasi. Količina hlapljivih organskih spojeva u prirodno fermentiranom mlijeku (naturally fermented milk – NFM) razlikovala se od uzorka do uzorka, te je iznosila 0,1-18,4 ppm acetaldehida, <0,1-0,47 ppm 3-metilbutanala i 39,3-656 ppm etanola. Upotrebom kulture LAB/C. kefyr 23 (B/Y1) proizvedena je kudikamo veća (p<0,05) količina acetaldehida i etanola nego u NFM. Količina acetaldehida u uzorcima B/Y1 iznosila je 26,7-87,7 ppm, a najviše acetaldehida dobiveno je fermentacijom s pomoću L. lactis subsp. lactis biovar. diacetylactis C1 (B4) u kombinaciji s C. kefyr 23 (Y1). Metodom glavnih komponenata (principal component analysis – PCA) svrstana je većina NFM uzoraka s pojedinačnim i mješovitim kulturama Lc261, Lb11 i kvascima koji ne fermentiraju laktozu, prema malim količinama etanola i sličnom udjelu 3-metilbutanala. Kromatogram prirodno fermentiranog mlijeka amasi pokazuje visok pik metilaldehida i njihovih alkohola, uključujući 3-metilbutanal i 3-metilbutanol, čime je dokazano da su ti spojevi značajni za mlijeko amasi

The politics of rurality (editorial)

Guest edited special issue of Landscape Research

Prognostic value of NT-proBNP for myocardial recovery in peripartum cardiomyopathy (PPCM)

Introduction Peripartum cardiomyopathy (PPCM) is an important cause of pregnancy-associated heart failure worldwide. Although a significant number of women recover their left ventricular (LV) function within 12 months, some remain with persistently reduced systolic function. Methods Knowledge gaps exist on predictors of myocardial recovery in PPCM. N-terminal pro-brain natriuretic peptide (NT-proBNP) is the only clinically established biomarker with diagnostic value in PPCM. We aimed to establish whether NT-proBNP could serve as a predictor of LV recovery in PPCM, as measured by LV end-diastolic volume (LVEDD) and LV ejection fraction (LVEF). Results This study of 35 women with PPCM (mean age 30.0 ± 5.9 years) had a median NT-proBNP of 834.7 pg/ml (IQR 571.2–1840.5) at baseline. Within the first year of follow-up, 51.4% of the cohort recovered their LV dimensions (LVEDD  50%). Women without LV recovery presented with higher NT-proBNP at baseline. Multivariable regression analyses demonstrated that NT-proBNP of ≥ 900 pg/ml at the time of diagnosis was predictive of failure to recover LVEDD (OR 0.22, 95% CI 0.05–0.95, P = 0.043) or LVEF (OR 0.20 [95% CI 0.04–0.89], p = 0.035) at follow-up. Conclusions We have demonstrated that NT-proBNP has a prognostic value in predicting LV recovery of patients with PPCM. Patients with NT-proBNP of ≥ 900 pg/ml were less likely to show any improvement in LVEF or LVEDD. Our findings have implications for clinical practice as patients with higher NT-proBNP might require more aggressive therapy and more intensive follow-up. Point-of-care NT-proBNP for diagnosis and risk stratification warrants further investigation

Resource allocation during COVID-19 : a focus on vulnerable populations

South Africa (SA) is a country of contrasts, with abundant resources, hard-won civil rights and a diverse population. Woven into the fabric of our society is a large divide between its poorest and its wealthiest members. In this article we highlight the vulnerabilities in our society that have been amplified by the COVID-19 crisis. Based on recent projections, it is very likely that the healthcare system will be overwhelmed. We acknowledge the recognition by government and civil society of these vulnerabilities, and note that difficult decisions will need to be made with regard to resource allocation. Our plea, however, is to ensure that human dignity and the principle of distributive justice are maintained, and that when difficult decisions are made, vulnerable people do not suffer disproportionately. Furthermore, it is of great concern that there is no national directive guiding resource allocation, prioritisation and triage decisions in both public and private hospitals. The Health Professions Council of SA should, as a matter of urgency, issue guidance on priority-setting and triage decisions in the context of COVID-19, based on distributive justice principles.The joint Department of Science and Technology and National Research Foundation Doctoral Innovation Scholarship, the SA Medical Research Council and the University of Pretoria (through the Institute for Cellular and Molecular Medicine).http://www.sajbl.org.zaam2021Immunolog

Factors associated with bone mineral density and bone resorption markers in postmenopausal hiv-infected women on antiretroviral therapy: A prospective cohort study

The study aimed to determine factors associated with changes in bone mineral density (BMD) and bone resorption markers over two years in black postmenopausal women living with human immunodeficiency virus (HIV) on antiretroviral therapy (ART). Women (n = 120) aged > 45 years were recruited from Potchefstroom, South Africa. Total lumbar spine and left femoral neck (LFN) BMD were measured with dual energy X-ray absorptiometry. Fasting serum C-Telopeptide of Type I collagen (CTx), vitamin D and parathyroid hormone were measured. Vitamin D insufficiency levels increased from 23% at baseline to 39% at follow up. In mixed linear models serum CTx showed no change from baseline to end (p = 0.363, effect size = 0.09). Total and LFN BMD increased significantly over two years, but effect sizes were small. No significant change in spine BMD over time was detected (p = 0.19, effect size = 0.02). Age was significantly positively associated with CTx over time, and negatively with total and LFN BMD. Physical activity (PA) was positively associated with LFN BMD (p = 0.008). Despite a decrease in serum vitamin D, BMD and CTx showed small or no changes over 2 years. Future studies should investigate PA interventions to maintain BMD in women living with HIV

Clinically contextualised ECG interpretation: the impact of prior clinical exposure and case vignettes on ECG diagnostic accuracy

Background ECGs are often taught without clinical context. However, in the clinical setting, ECGs are rarely interpreted without knowing the clinical presentation. We aimed to determine whether ECG diagnostic accuracy was influenced by knowledge of the clinical context and/or prior clinical exposure to the ECG diagnosis. Methods Fourth- (junior) and sixth-year (senior) medical students, as well as medical residents were invited to complete two multiple-choice question (MCQ) tests and a survey. Test 1 comprised 25 ECGs without case vignettes. Test 2, completed immediately thereafter, comprised the same 25 ECGs and MCQs, but with case vignettes for each ECG. Subsequently, participants indicated in the survey when last, during prior clinical clerkships, they have seen each of the 25 conditions tested. Eligible participants completed both tests and survey. We estimated that a minimum sample size of 165 participants would provide 80% power to detect a mean difference of 7% in test scores, considering a type 1 error of 5%. Results This study comprised 176 participants (67 [38.1%] junior students, 55 [31.3%] senior students, 54 [30.7%] residents). Prior ECG exposure depended on their level of training, i.e., junior students were exposed to 52% of the conditions tested, senior students 63.4% and residents 96.9%. Overall, there was a marginal improvement in ECG diagnostic accuracy when the clinical context was known (Cohen’s d = 0.35, p < 0.001). Gains in diagnostic accuracy were more pronounced amongst residents (Cohen’s d = 0.59, p < 0.001), than senior (Cohen’s d = 0.38, p < 0.001) or junior students (Cohen’s d = 0.29, p < 0.001). All participants were more likely to make a correct ECG diagnosis if they reported having seen the condition during prior clinical training, whether they were provided with a case vignette (odds ratio [OR] 1.46, 95% confidence interval [CI] 1.24–1.71) or not (OR 1.58, 95% CI 1.35–1.84). Conclusion ECG interpretation using clinical vignettes devoid of real patient experiences does not appear to have as great an impact on ECG diagnostic accuracy as prior clinical exposure. However, exposure to ECGs during clinical training is largely opportunistic and haphazard. ECG training should therefore not rely on experiential learning alone, but instead be supplemented by other formal methods of instruction

Early interactions with newly diagnosed TB patients in hospital can support linkage to care

BACKGROUND: In South Africa, failure to link individuals diagnosed with TB to care remains an important gap in the TB care cascade. Compared to people diagnosed at primary healthcare (PHC) facilities, people diagnosed in hospitals are more likely to require additional support to be linked with PHC TB treatment services. We describe a patient interaction process to support linkage to TB care. METHODS: We implemented a step-by-step early patient interaction process with 84 adults newly diagnosed with TB in one district hospital in Khayelitsha, Cape Town, South Africa (August 2020–March 2021). We confirmed patient contact details, provided TB and health information, shared information on accessing care at PHC facilities and answered patients’ questions in their home language. RESULTS: Most patients (54/84, 64%) provided updated telephone numbers, and 19/84 (23%) reported changes in their physical address. Patients welcomed practical and health information in their home language. The majority (74/84, 88%) were linked to care after hospital discharge. CONCLUSIONS: A simple early patient interaction process implemented as part of routine care is a feasible strategy to facilitate early TB treatment initiation and registration