Thin Layer chromatographic analyses of pesticides in a soil ecosystem

Silica gel 60, silica gel 60 F254, and aluminium oxide as adsorbents were used to investigate their suitability for the analysis and detection of the pesticides: nitrofen, atrazine, diuron, dioxacarb, propoxur, propanil, carbaryl and cypermethrin in soil ecosystem using ethyl acetate, chloroform, dichloromethane and ethyl acetate/chloroform (1:1) as developing solvents. O-tolidine and potassium iodide reagent were used for the detection of the pesticides. Rf values obtained for the pesticides using the silica gel 60-ethyl acetate, silica gel 60 F254-ethyl acetate, silica gel 60-chloroform, silica gel 60 F254-chloroform, silica gel 60 – (1:1) ethyl acetate/chloroform and silica gel 60 F254 – (1:1) ethyl acetate/chloroform systems generally were within the stipulated range of 0.4 –0.8. Rf values obtained for the pesticides using silica gel 60-dichloromethane and silica gel 60 F254-dichloromethane systems were very low except for cypermethrin and nitrofen. Analysis with aluminium oxide coated plates gave a heavy yellow background with the detection reagent making visualization of spots difficult. Aluminium oxide coated plate is, therefore, not recommended when o-tolidine plus potassium iodide is used as detection reagent

Comparison of two detection methods in thin layer chromatographic analysis of some herbicides in a Coastal Savanna Soil in Ghana

o-tolidine plus potassium iodide and photosynthesis inhibition detection methods were investigated for the analysis of three triazine herbicides (atrazine, ametryne, simazine) and two urea herbicides (diuron, metobromuron) in a coastal savanna soil using thin layer chromatography to compare the suitability of the two methods for the study of the herbicides. This was done by spiking 5 g of the soil sample with specific amount of the herbicide standards to generate herbicide-soil concentration of 40.24, 41.46, 40.28, 39.90 and 40.64 ìg/g for atrazine, ametryne, simazine, diuron and metobromuron, respectively. Extraction was performed with acetone/hexane mixture (4:1) and the detection limit of each herbicide was then determined. In all, the photosynthesis inhibition method performed better for both the triazine and the urea herbicides, while the o-tolidine plus potassium iodide method was suitable for only the triazine herbicides. With the photosynthesis inhibition method, detectability in the range of 0.004–0.008 ± 0.002 ìg/g was attained for the herbicides using the unclean extracts. In the case of o-tolidine plus potassium iodide method, detectability of 0.008–0.406 ± 0.02 ìg/g was obtained. With the clean up extracts detectability in the range of 0.025–0.162 ± 0.004 ìg/g was obtained using the photosynthesis inhibition method. However, metobromuron was not detected in the cleaned up extracts when o-tolidine plus potassium iodide detection method was used. For the methods described, clean up with SPE cartridge, equipped with C-18, is not critical to obtain the desired results

Randomized controlled trials are needed to close the evidence gap in the prevention of preterm birth

Pregnant women have been advised to avoid heavy lifting during pregnancy due to concerns of adverse pregnancy outcomes including premature delivery. To date there is no evidence on the effectiveness of advice in preventing preterm birth as found in a recent systematic search and appraisal of published literature. This letter employs the findings of the review to inform future studies

Spread of African cassava mosaic virus from cassava (Manihot esculenta Crantz) to physic nut (Jatropha curcas L.) in Ghana

Investigations were made on the susceptibility of physic nut (Jatropha curcas L.) to African cassava mosaic virus (ACMV) and its possible role as an alternative host of the virus in Ghana. Ten J. curcas accessions in a field trial were interplanted with ACMV-infected cassava (Manihot esculenta Crantz) and left to natural spread of the virus from the cassava to the J. curcas plants for a period of 12 months. Populations of the whitefly vector, Bemisia tabaci (Gennadius) and the incidence of African cassava mosaic disease (ACMD) were monitored during the period. The J. curcas plants had low whitefly numbers, both in the wet (September – October, 2008) season and in the dry (January – February, 2009) season. By the end of the experimental period, 37.7% of the 120 J. curcas plants tested in all the accessions were found to be infected by ACMV, as assessed by symptom expression, double antibody-sandwich (DAS) ELISA or sap inoculation to Nicotiana benthamiana indicator plants. There were wide variations within and between the J. curcas accessions in their response to ACMV infection. This work is the first report of the natural infection of J. curcas by ACMV

Effect of mosaic virus diseases on dry matter content and starch yield of five cassava (Manihot esculenta Crantz) accessions in Ghana

The effect of mosaic virus diseases on dry matter content and starch yield of five local accessions of cassava, “Ankrah”, “AW/17, “Tomfa”, “Dagarti” and “Tuaka” was evaluated. Tomfa showed the highest (95%) incidence of the disease, index of severity of symptoms for all plants (ISSAP) of 3.70, as well as, for diseased plants (ISSDP) (3.84) while Dagarti did not show any phenotypic expression of the disease throughout the study period. Most of the accessions displayed mosaic disease symptoms two months after planting but by the fifth month had fully recovered. However, polymerase chain reaction (PCR)-based testing at 12 months after planting revealed the presence of ACMV in all the accessions while EACMV was observed in Ankrah, Dagarti and AW/17. Mean tuber (fresh root weight) and starch yield at 12 months after planting (MAP) was significantly (P ≤ 0.05) high in Ankrah while percentage dry matter was significantly higher in Dagarti than the other accessions. A negative correlation between starch yield and cassava mosaic disease incidence implies that a high mosaic incidence particularly in the first three months results in lower tuber and starch yields.Keywords: Mosaic virus diseases, dry matter, starch yield, PCR, disease incidenceAfrican Journal of Biotechnology Vol. 12(27), pp. 4310-431

Using fuzzy PROMETHEE to select countries for developmental Aid

Wealthy nations continue to demonstrate their unwavering support to improving conditions and the general well-being of poor countries in spite of the recent economic crises. However, as developmental aid relatively shrinks, both Aid donors and recipient countries have shown keen interest in methodologies used in evaluating developmental assistance programs. Evaluation of aid programs is seen as a complex task mainly because of the several non-aid factors that tend to affect overall outcomes. Adding to the complexity are the subjective sets of criteria used in Aid evaluations programs. This paper proposes a two stage framework of fuzzy TOPSIS and sensitivity analysis to demonstrate how aid-recipient countries can be evaluated to deepen transparency, fairness, value for money and sustainability of such aid programs. Using the Organisation for Economic Co-operation and Development (OECD) set of subjective criteria for evaluating aid programs; a numerical examplepre-defined by linguistic terms parameterized by triangular fuzzy numbers is provided to evaluate aid programs. Fuzzy PROMETHEE is used in the first stage to evaluate and rank aid-recipients followed by a comparative analysis with Fuzzy VIKOR and Fuzzy TOPSIS to ascertain an accurateness of the method used. A sensitivity analysis is further added that anticipates possible influences from lobbyists and examines the effect of that bias in expert ratings on the evaluation process. The result shows a framework that can be employed in evaluating aid effectiveness of recipient-countries

Schwannoma extending from the umbilical region to the mid-thigh, compressing the major vessels of the right leg: A case report and review of the literature

Schwannomas are benign, usually encapsulated, nerve sheath tumours derived from Schwann cells. They commonly arise from the cranial nerves as acoustic schwannomas and are extremely rare in the pelvis and retroperitoneal area (<0.5% of reported cases) unless they are combined with Von Recklinghausen disease (type 1 neurofibromatosis). We report the case of a 23-year-old woman with a mass extending from the umbilical region in the abdomen to the upper two-thirds of the thigh. As this tumour is so rare, and in order to ensure optimal treatment and survival for our patient, a computed tomography-guided biopsy was performed before en bloc tumour excision. Because of the possibility of malignancy, complete excision of the mass was performed, with pelvic blunt dissection. Histological examination showed a benign neoplasm, originating from the cells of peripheral nerve sheaths; the diagnosis was a schwannoma. Abdominal schwannomas are rare neoplasms that can be misdiagnosed. Laparoscopy is a safe and efficient option for approaching benign pelvic tumours and may offer the advantage of better visualisation of structures owing to the magnification in laparoscopic view, especially in narrow anatomical spaces. However, in our case laparoscopy was not considered owing to the size and anatomical location of the tumour

Mechanisms underlying a thalamocortical transformation during active tactile sensation

During active somatosensation, neural signals expected from movement of the sensors are suppressed in the cortex, whereas information related to touch is enhanced. This tactile suppression underlies low-noise encoding of relevant tactile features and the brain’s ability to make fine tactile discriminations. Layer (L) 4 excitatory neurons in the barrel cortex, the major target of the somatosensory thalamus (VPM), respond to touch, but have low spike rates and low sensitivity to the movement of whiskers. Most neurons in VPM respond to touch and also show an increase in spike rate with whisker movement. Therefore, signals related to self-movement are suppressed in L4. Fast-spiking (FS) interneurons in L4 show similar dynamics to VPM neurons. Stimulation of halorhodopsin in FS interneurons causes a reduction in FS neuron activity and an increase in L4 excitatory neuron activity. This decrease of activity of L4 FS neurons contradicts the "paradoxical effect" predicted in networks stabilized by inhibition and in strongly-coupled networks. To explain these observations, we constructed a model of the L4 circuit, with connectivity constrained by in vitro measurements. The model explores the various synaptic conductance strengths for which L4 FS neurons actively suppress baseline and movement-related activity in layer 4 excitatory neurons. Feedforward inhibition, in concert with recurrent intracortical circuitry, produces tactile suppression. Synaptic delays in feedforward inhibition allow transmission of temporally brief volleys of activity associated with touch. Our model provides a mechanistic explanation of a behavior-related computation implemented by the thalamocortical circuit

Parallel Driving and Modulatory Pathways Link the Prefrontal Cortex and Thalamus

Pathways linking the thalamus and cortex mediate our daily shifts from states of attention to quiet rest, or sleep, yet little is known about their architecture in high-order neural systems associated with cognition, emotion and action. We provide novel evidence for neurochemical and synaptic specificity of two complementary circuits linking one such system, the prefrontal cortex with the ventral anterior thalamic nucleus in primates. One circuit originated from the neurochemical group of parvalbumin-positive thalamic neurons and projected focally through large terminals to the middle cortical layers, resembling ‘drivers’ in sensory pathways. Parvalbumin thalamic neurons, in turn, were innervated by small ‘modulatory’ type cortical terminals, forming asymmetric (presumed excitatory) synapses at thalamic sites enriched with the specialized metabotropic glutamate receptors. A second circuit had a complementary organization: it originated from the neurochemical group of calbindin-positive thalamic neurons and terminated through small ‘modulatory’ terminals over long distances in the superficial prefrontal layers. Calbindin thalamic neurons, in turn, were innervated by prefrontal axons through small and large terminals that formed asymmetric synapses preferentially at sites with ionotropic glutamate receptors, consistent with a driving pathway. The largely parallel thalamo-cortical pathways terminated among distinct and laminar-specific neurochemical classes of inhibitory neurons that differ markedly in inhibitory control. The balance of activation of these parallel circuits that link a high-order association cortex with the thalamus may allow shifts to different states of consciousness, in processes that are disrupted in psychiatric diseases