Carbon dioxide emission, nitrogen mineralisation and spinach dry matter yield in a loamy humic soil amended with lime and poultry manure.

While application of lime and poultry manure (PM) increase availability of mineral N in acidic humic soils (> 1.8% organic carbon), these amendments enhance decomposition of soil organic carbon (SOC) increasing carbon dioxide (CO2) emissions. This study investigated the effects of co-application of PM and lime on (i) CO2 emission, (ii) concentration of mineral-N and (iii) spinach dry matter yield and nutrient uptake in a humic soil. Two incubation experiments were set up for 84 days to determine (i) CO2 emission and (ii) mineral-N on soils from the 0-10- and 10-20-cm depths. The treatments were PM (10 t ha-1), lime (12 t ha-1), PM + lime and unamended control. Same treatments (with inclusion of inorganic fertilisers) were applied to a pot trial using soils (0-10-cm depth) that were pre-incubated for 0, 14 and 35 days before planting spinach, and dry matter yield and N uptake were determined. Co-application of PM and lime significantly decreased ammonium-N in soil at both depths but increased nitrate-N and CO2 emission than lime alone. Poultry manure significantly increased ammonium-N and CO2 emission at 0-10-cm depth. For all treatments, cumulative CO2-C was significantly higher at 0-10 cm. Dry matter yield for PM + lime and lime + mineral N was higher than when separately applied. Pre-incubation of soils with lime and PM, separately or in combination, increased dry matter yield. These findings imply that application of PM and lime in humic soils increases mineral-N availability and crop productivity, especially when pre-incubated for 35 days, whilst the increase in CO2 emission could result in the decrease of SOC.

Effects of lime application on nitrogen and phosphorus availability in humic soils.

There is a paucity of information on nitrogen (N) and phosphorus (P) mineralization in humic soils, which are highly weathered and have high carbon (C) (>1.8%). This study was to determine effects of liming on N and P mineralization in humic soils. Lime was applied to reduce acid saturation to 20% of the 0-10 and 10-20 cm depths of soils from Eston and Eshowe. Soils were incubated at field capacity moisture and 25 °C temperature, with destructive sampling after 0, 7, 14, 21, 28, 56, 84 and 112 days. Samples were analysed for pH, ammonium- and nitrate-N and extractable P. Phosphorus pools and soil microbial biomass C and N (SMBC and N) were analysed after 112 days only. Soil pH increased up to day 7 and decreased thereafter in Eston soil but decreased throughout the incubation in Eshowe soil. Ammonium- and nitrate-N increased with lime rate, with ammonium-N peaking after 7 and 14 days for Eston and Eshowe soils, respectively. The 0-10 cm depth had higher ammonium-N than 10-20 cm for both soils. Nitrate-N increased with corresponding decrease in ammonium-N. Extractable P decreased till day 21 and increased thereafter in Eston soil, with slight changes in Eshowe. Higher lime rate decreased Al-P, Fe-P and CBD-P and increased soluble-P, Ca-P, and SMB-C and N for both soils. The findings imply that liming humic soils increase nitrate-N and, to a lesser extent, extractable P, possibly improving productivity and exposing N to leaching.

Sliding wear and friction characteristics of polymer nanocomposite PAEK-PDMS with nano-hydroxyapatite and nano-carbon fibres as fillers.

The development of a suitable polymeric bioactive composite with hydroxyapatite as a filler is one of the very actively pursued areas in bioapplications. This report concerns development of such a novel polymeric biocomposite viz. poly (aryl ether) ketone-poly (dimethylsiloxane) with a small percentage of nano carbon fibres and varying percentages of nanohydroxyapatite particulates as fillers. The earlier characterization of this material involving mechanical, thermal and bio-compatibility studies showed optimum improved behaviour at about 7% nanohydroxyapatite loading as reported elsewhere. In this study, the wear and friction response of this biocomposite was tested in air under dry sliding conditions against hard steel using a pin-on-disc apparatus. Interestingly, the adhesive wear characteristics of this nanocomposite with varying nanohydroxyapatite percentages showed a trend similar to that in other characteristics with lowest wear occurring around the same nanohydroxyapatite percentage. It was observed that the specific wear rate in this novel nanocomposite was exceptionally low [~ 10-8 (mm3/N-m)] compared to that in other similar polymer composites. The origin of this very low wear rate can be associated with the multiple strategies used in the preparation of this nanocomposite such as the use of poly (dimethylsiloxane) which is known to provide a cushioning effect in the matrix. In addition, the phosphate grafting of poly (dimethylsiloxane), the nanonature of both the fillers and their specific surface treatments using aminosilane for enhancing the matrix- filler interfacial bonding all of them seem to have played their expected beneficial roles resulting in the above very low wear rate. The earlier studies on this nanocomposite have shown improvement of the mechanical compressive strength with the addition of carbon nanofibres. Interestingly, here the friction coefficient of the nanocomposite with carbon nanofibres is consistently higher than that without carbon nano fibres for different nanohydroxyapatite percentages samples, for both low (5 N) as well as high (30 N) applied load. It could possibly be due to dislodged carbon nano fibres acting as a third body abrasive or fibres acting as weak links in the matrix filler network affecting the friction response. These wear and friction measurements have clearly brought out the various interesting aspects of the tribological response of the nanocomposite material and the intricate roles played by its matrix component poly (dimethylsiloxane) and the surface treated nano fillers nanohydroxyapatite and nano carbon fibre.

A National Survey of Oxytocin Use during Caesarean Section in Zimbabwe

Background: Post-partum haemorrhage is the leading cause of mortality for labouring women in Zimbabwe. Current literature supports the use of low dose oxytocin to prevent bleeding during Caesarean section. Internationally; clinical practice has been slow to change and the use of potentially harmful; higher than recommended dose is common.Objective: To describe the current clinical practice in Zimbabwe.Design: A self-administered questionnaire survey. Descriptive statistics were used to report the study results.Setting: In 2013 a national survey was conducted on the use of oxytocin by different types of clinicians; who provide either anaesthesia or surgery for Caesarean section.Results: Of a total of 221 (61%) questionnaires returned; 170 (80%) were completed fully. Only 23% of respondents would give an intravenous dose of 5.0 IU or less of oxytocin for elective Caesarean section. The majority of clinicians (77%) would administer more than 5.0 IU of oxytocin at elective. A significant number of nurse anaesthetists 16/59 (27%); and a non-negligible number of specialist anaesthetists 3/48 (6%) would even give 20 IU of oxytocin in elective cases rising to 30% and 13% respectively for emergency cases. In case of persistent bleeding due to uterine atony; oxytocin was more likely to be repeated (45%); rather than using misoprostol (25%) or ergometrine (19%). Conclusion: Most clinicians in Zimbabwe use oxytocin doses well above current internationally recommended. This illustrates the urgent need for updated national guidelines for the prevention of post-partum haemorrhage during Caesarean section

Effect of topical corticosteroids on allergic airway inflammation and disease severity in obstructive sleep apnoea.

BACKGROUND: The incidence of sleep-related breathing disorders is correlated with lower and upper airway inflammatory diseases, such as asthma and allergic rhinitis. We hypothesized that corticosteroids treatment would lead to a greater reduction in disease severity in obstructive sleep apnoea syndrome (OSAS) patients with concomitant allergic rhinitis vs. non-allergic OSAS patients by reducing the level of inflammation in upper airway tissues. OBJECTIVE: This study was performed to determine whether treatment with intranasal corticosteroids could reduce upper airway inflammation and improve sleep parameters in obstructive sleep apnoea syndrome patients with or without concomitant allergic rhinitis. METHODS: Obstructive sleep apnoea syndrome patients with (n = 34) or without (n = 21) documented allergic rhinitis voluntarily enrolled in the study and were assessed at baseline and after corticosteroids treatment for 10-12 weeks. Sleep studies were performed and biopsies were obtained from the inferior turbinate, nasopharynx, and uvula. The apnoea-hypopnoea index, sleep quality, and level of daytime alertness were determined, and immunocytochemistry was used to phenotype tissue inflammation. RESULTS: Standard sleep indices improved following treatment in the entire cohort of obstructive sleep apnoea syndrome patients, with greater improvement seen in the allergic rhinitis group. Allergic rhinitis patients demonstrated significantly improved O2 saturation and a lower supine apnoea-hypopnoea index score after corticosteroid treatment; similar improvements were not seen in the non-allergic rhinitis group. Eosinophilia was detected at all three sites in the allergic rhinitis group, but not in the non-allergic rhinitis group. Following treatment, fewer eosinophils and CD4 lymphocytes were documented at all three biopsy sites in the allergic group; the reduction in inflammation was less apparent in the non-allergic rhinitis group. CONCLUSION: This study has provided important molecular and clinical evidence regarding the ability of corticosteroids to reduce upper airway inflammation and improve obstructive sleep apnoea syndrome morbidity patients with concomitant allergic rhinitis.

Risk of nevirapine-associated Stevens-Johnson syndrome among HIV-infected pregnant women: the Medunsa National Pharmacovigilance Centre, 2007 - 2012.

BACKGROUND: Stevens-Johnson syndrome (SJS) is an acute life-threatening condition often elicited by drugs. The government's indecisiveness in deciding to stop the use of nevirapine (NVP) in HIV-infected pregnant women owing to the increase of SJS among this population group in South Africa prompted this investigation. OBJECTIVES: To investigate if pregnancy is a risk factor for SJS among HIV-infected women taking NVP-containing regimens and registered within the Medunsa National Pharmacovigilance Centre database. METHODS: A matched case-control study with 5:1 matching was conducted. Women with SJS (cases) taking NVP-containing regimens were matched with women without SJS (controls) taking NVP-containing regimens. Controls were randomly selected and matched to cases by hospital, age, treatment duration and CD4 count. Conditional logistic regression was used to determine if pregnancy was a risk factor for SJS. RESULTS: Six SJS cases were identified and 30 controls selected. The median age of both cases and controls was 29 years and the average CD4 counts were 237 and 234 cells/microl respectively. Subjects were on NVP treatment for 18 - 31 days before the onset of SJS. Controls did not develop SJS after treatment of between 1 and 365 days. Pregnancy increased the chances of developing SJS 14-fold (OR 14.28, p = 0.006, 95% CI 1.54 - 131.82). CONCLUSIONS: NVP-containing ARV regimens taken during pregnancy increase the risk of developing SJS. Healthcare workers are advised to offer informed consent to patients and recommend effective contraception methods if NVP treatment is considered. In the light of our findings, further studies of the association between NVP, pregnancy and SJS are necessary before general conclusions can be reached.

Sanctuary or Double-Edged Sword? Challenges Confronting Adolescents Living at Nkosi's Haven in Johannesburg; South Africa

Living in an institution associated with HIV and AIDS is likely to exacerbate difficulties experienced by teenagers who have to cope with the normal stresses of adolescence. The aim of the study was to explore the challenges that adolescents living at Nkosi's Haven encounter and whether they experience any problems when interacting with their peers and other members of the community. The study was located within a qualitative research paradigm and utilised a purposive; non-probability sample of 15 participants recruited from two Nkosi's Havens. A semi-structured interview schedule was employed as the research tool; with in-depth one-on-one interviews adopted as the method of data collection. Thematic content analysis was used to analyse the data collected during the interviews. The main finding that emanated from the study was that Nkosi's Haven is indeed a place of care and nurturing as adolescents are afforded the opportunity to continue with their educational needs while basic and psychosocial needs are also addressed. However; it also emerged that rejection; discrimination; social exclusion and stigmatisation associated with the setting make it difficult for resident adolescents to integrate freely with their peers at school and in the community. The conclusion drawn is that Nkosi's Haven can be regarded as a double-edged sword as it presents both positive and negative factors that impact on its resident adolescents. Results are discussed in terms of their implications for community awareness programmes; policies and practice changes regarding employment and training of staff; and visiting of parents as well as future research

Substrate-trapping techniques in the identification of cellular PTP targets.

Tyrosine phosphorylation is negatively regulated by the protein-tyrosine phosphatases (PTPs). In order to find the physiological substrates of these enzymes, diverse PTP mutants that do not possess any catalytic activities but appear to bind tightly to their tyrosine phosphorylated substrates have been designed. Hence, they can be used as tools to pull out their respective substrates from heterogeneous extracts. Named PTP "substrate-trapping" mutants by the Tonks laboratory, they represent a diverse variety of defective PTPs that are epitomized by the Cys to Ser mutant (C/S) where the active cysteine residue of the signature motif is mutated to a serine residue. In addition, new mutants have been developed which are expected to help characterize novel and less abundant substrates. In this article, we review and describe all the different substrate-trapping mutants that have successfully been used or that hold interesting promises. We present their methodology to identify substrates in vivo (co-immunoprecipitation) and in vitro (GST pulldown), and provide a current list of substrates that have been identified using these technologies.

Lipoprotein(a) concentrations and apolipoprotein(a) isoform distribution in a Zimbabwean population.

OBJECTIVE: To determine serum lipoprotein(a)[Lp(a)] concentrations and apolipoprotein(a)[apo(a)] phenotypes in a Zimbabwean population. DESIGN: Cross sectional study. SETTING: Blood Transfusion Services, Harare, Zimbabwe. SUBJECTS: 84 black and 40 white blood donors. MAIN OUTCOME MEASURES: Lp(a) concentrations and apo(a) phenotypes. RESULTS: The mean and median values for Lp(a) concentrations were 506 and 350 mg/L for the black subjects and 278 and 142 mg/L for the white subjects (p < 0.005). The frequency distributions of Lp(a) concentrations for both populations were skewed to the right. The frequency distribution of apo(a) size, expressed as the number of kringle IV repeats, was determined. Comparison of the frequency distribution plots showed very similar isoform distributions between the two groups. The documented inverse relationship between apo(a) size and Lp(a) concentration was observed in the white population. CONCLUSION: The Lp(a) levels in the black population were two to three fold higher than in the white population whilst no differences in apo(a) phenotype distribution were noted. This suggests that environmental and metabolic factors may be responsible for the elevated Lp(a) levels observed in blacks. Thus different pathological thresholds may have to be established for elevated serum Lp(a) levels to be used as a risk marker for coronary heart disease in black populations.

Modulation of intestinal and liver fatty acid-binding proteins in Caco-2 cells by lipids, hormones and cytokines.

Intestinal and liver fatty acid binding proteins (I- and L-FABP) are thought to play a role in enterocyte fatty acid (FA) trafficking. Their modulation by cell differentiation and various potential effectors was investigated in the human Caco-2 cell line. With the acquisition of enterocytic features, Caco-2 cells seeded on plastic progressively increased L-FABP quantities, whereas I-FABP was not detectable even very late in the maturation process. On permeable filters that improved differentiation markers (sucrase, alkaline phosphatase, transepithelial resistance), Caco-2 cells furthered their L-FABP content and expressed I-FABP. Western blot analysis showed a significant increase in I- and L-FABP expression following an 8-hour incubation period with butyric acid, oleic acid, and phosphatidylcholine. However, in all cases, I-FABP levels were higher than L-FABP concentrations regardless of the lipid substrates added. Similarly, hydrocortisone and insulin enhanced the cellular content of I- and L-FABP whereas leptin triggered I-FABP expression only after an 8-hour incubation. Finally, tumor necrosis factor-alpha was more effective in increasing the cytosolic amount of I-FABP levels. In conclusion, our data demonstrate that I-FABP expression is limited to fully differentiated Caco-2 cells and can be more easily regulated than L-FABP by lipids, hormones, and cytokines.

Modulation of endoplasmic reticulum-bound cholesterol regulatory enzymes by iron/ascorbate-mediated lipid peroxidation.

Mammalian sterol regulatory enzymes are integral membrane proteins of the endoplasmic reticulum. They play a critical role in liver cholesterol homeostasis and the maintenance of overall cholesterol balance in different species. Because lipid peroxidation has been implicated in hepatic dysfunction and atherosclerosis, we hypothesized that its occurrence could alter the composition and properties of the bilayer lipid environment, and thereby affect the functions of these membrane proteins. Preincubation of rat liver microsomes with iron (Fe)/ascorbate (50 microM/200 microM), known to induce peroxidation, resulted in a significant inhibition of (i) the rate-limiting enzyme in cholesterol biosynthesis, HMG-CoA reductase (46%, p < .01), (ii) the crucial enzyme controlling the conversion of cholesterol in bile acids, cholesterol 7alpha-hydroxylase (48%, p < .001), and (iii) the central enzyme for cholesterol esterification: Acyl-CoA:cholesterol acyltransferase (ACAT, 80%, p < .0001). The disturbances of these key enzymes took place concomitantly with the high production of malondialdehyde (350%, p < .007) and the loss of polyunsaturated fatty acids (36.19 +/- 1.06% vs. 44.24 +/- 0.41 in controls, p < .0008). While alpha-tocopherol simultaneously neutralized lipid peroxidation, preserved microsomal fatty acid status, and restored ACAT activity, it was not effective in preventing Fe/ascorbate-induced inactivation of both HMG-CoA reductase (44%, p < .01) and cholesterol 7alpha-hydroxylase (71%, p < .0001). These results indicate that Fe/ascorbate alters the activity of the rate-determining steps in liver cholesterol metabolism, either directly or via lipid peroxidation, capable of modifying their membrane environment. The present data also suggest that the three regulatory enzymes respond differently when exposed to Fe/ascorbate or antioxidants, which may be due to dissimilar mechanisms.

Influence of stressful life events on the onset of Type 1 diabetes in childhood.

The study focuses on the effects of different psychosocial stress on the onset of Type 1 diabetes in Zimbabwe. Type 1 diabetic children were compared with healthy control group. A set of relevant anthropometric indices was used to asses their physical development and fitness. Diabetic children were admitted to hospital with diabetic ketoacidoses, high blood glucose levels and severe dehydration. It was difficult to achieve stable long-term metabolic control because of acute infections , diatery lapses, frequent hypoglycemic attacks due to poverty and malnutrition, lack of intensive insulin therapy and glucose monitoring. It was found that diabetic children had higher heart rates (97.7 bts/min) and showed lower results when submitted to apnoeic test (20.6 sec) and tipping test (233.2 points). Stressful events that occurred within the family during the year prior to the clinical, onset of Type 1 diabetes were recorded on an inventory consisting of 45 questions. The total frequency of stressful life events were higher for diabetic children (95.4) than in the control group.(4.2). The relative frequencies of events that included actual or threatened loss within the family were significantly higher for the diabetic children (32-53%). In conclusion, severe emotional stress induced by life events such as the birth of another sibling, the influence of a step-parent, serious illness of the mother, marital separation or divorce of parents and the change in parent's financial status are associated with the onset of childhood diabetes and may be considered as risk factors.

The influence of dietary fat on hepatic bioactivation of aflatoxin B1 in rats.

Fischer 344 rats were fed a low-fat high carbohydrate (HC) diet, an isocaloric fat-containing (IC) diet, a hypercaloric fat-containing (HF) diet or a commercial rodent chow. The effects of these diets were studied on the binding of aflatoxin B (AFB1) to exogenous DNA, and on the activities of hepatic glutathione transferases (GSTs), cytochromes 2B1 and 1A1. Microsome-mediated binding of [3H]AFB1 to exogenous DNA was significantly lower in the HC-rats than in the chow and IC-fed rats. No significant differences were noted between HF and either HC or IC rats. There was no significant difference in hepatic GST activity of rats fed the different diets. Our results suggest that high-carbohydrate low-fat diets reduce microsome mediated epoxidation of AFB1 to a larger extent than high-fat diets. In general, high fat diets increased cytochrome 1A1 and 2B1 activities relative to chow and high carbohydrate diet. This suggests greater detoxification of AFB1, thus reducing the amount of AFB1 available for hepatic macromolecular binding.

The effect of diet on aflatoxin B1 binding to hepatic macromolecules in rats.

Fischer 344 rats were fed a low-fat high carbohydrate diet (HC), an isocaloric fat-containing diet (IC), a hypercaloric fat-containing diet (HF) or rat chow. Covalent binding of AFB1 to liver DNA, RNA and total proteins was investigated in a 24 hour period following administration of a single intraperitoneal dose of AFB1 (1 mg/kg body weight). AFB1 binding to nucleic acids was greatest in the HC and was generally significantly lower (p < 0.05) in the HF, IC and rats fed chow. The results suggest that fat decreases hepatic macromolecular adduct formation by inhibiting activation of AFB1 to the epoxide or by enhancing the activity of detoxification pathways.