8 research outputs found
Soil slaking sensitivity as influenced by soil properties in alluvial and residual humid tropical soils
Purpose: In the humid Caribbean region characterized by high intensity tropical rainfall, soil
aggregate breakdown and pore blocking due to slaking pressures are major land degradation
mechanisms. In this research, we investigated the susceptibility of soils to slaking pressures
under rapid wetting as influenced by soil properties and the depositional origin from which the
soil is formed using water stable aggregates (WSAr) and percolation stability (PSc) as indices of
the strength of aggregate inter-particle cohesion.
Materials and methods: Wet sieving and percolation stability analyses were employed to
investigate WSAr and pore blocking, respectively. The combined effect of soil properties of
clay, organic matter (OM), cation exchange capacity (CEC) and exchangeable sodium
percentage (ESP) was used to determine the slaking sensitivity score (SSc) of fourteen
physiogeographically important soils in Trinidad, comprising of nine alluvial and five residual
soils.
Results and discussion: Results showed that irrespective of alluvial or residual depositional
nature of the parent material, samples had high SSc with an average WSAr of 37.8% and PSc of
6.0mm/10 minutes. The linear relationships between SSc with WSAr (r2 = -0.12) and SSc with
PSc (r2 = -0.012) of all the 14 soils although negative were weak. Clay content accounted for
94.0% of the variation in CEC in alluvial soils and had a strong negative relationships with
WSAr (r2 = -0.74) and PSc (r2 = -0.79) in residual soils. Additionally, OM with WSAr (r2 = 0.52)
and PSc (r2 = 0.24), and CEC with WSAr (r2 = 0.46) and PSc (r2 = 0.39) showed significant
positive linear relationships in residual soil.
Conclusions: The predominantly micaceous and kaolinitic clay mineralogy of these soils
coupled with the low OM contents, increase the proneness of the soils to slaking. This suggests
that clay mineralogy is responsible for the high slaking sensitivity rather than clay content or just
the depositional origin of the soils. As CEC increases, an accompanying increase in OM is
required to increase inter-particle cohesion and to impart partial hydrophobicity, which in turn
decreases mineralogically induced susceptibility of individual aggregates to slaking
Phytochemical analysis and antioxidant activity of methanolic extract of <i style="mso-bidi-font-style:normal">Plectranthus hadiensis </i>(Forssk.) Schweinf. ex Spreng. aerial parts
359-365Herbal medicine has been in use by diverse
civilizations in different parts of the world for centuries. Present study investigates
the phytochemical constitution of the methanolic extract of the aerial part of Plectranthus hadiensis (Forssk.)
Schweinf. ex Spreng. The preliminary phytochemical screening of the methanolic
extract had revealed high content of phenolics which was confirmed by TLC,
HPTLC and HPLC studies. The antioxidant activity was checked using DPPH assay,
nitric oxide radical scavenging activity assay and reducing power assay. The
methanolic extract showed considerably high antioxidant activity compared to the
standards used, viz. ascorbic acid and BHT (Butylated Hydroxy Toluene). The
presence of phenolics supported medicinal uses of the species and active
biomolecules could be isolated for pharmaceutical applications
EEG Patterns in Patients With Calcified Neurocysticercosis With or Without Hippocampal Atrophy
Purpose: To assess whether hippocampal atrophy develops in conjunction with clinical or subclinical epileptiform or encephalopathic activity in subjects with neurocysticercosis (NCC).
Methods: Using a population-based and nested case control study design, scalp EEGs and brain MRIs were performed in Atahualpa residents aged >= 40 years, who have imaging confirmed NCC (case patients), as well as in age- and sex-matched NCC-free control subjects.
Results: Sixty-two case patients and 62 control subjects were included. Encephalopathic EEG patterns were more common in five NCC subjects with epilepsy than in those without a history of seizures. Epileptiform EEG activity was noted in one patient with NCC but in none of the control subjects. This subject's focal epileptiform discharges correlated with the location of calcified cysticerci in the brain parenchyma, and the hippocampus ipsilateral to the epileptiform discharges was more atrophic than the contralateral hippocampus. The degree of hippocampal atrophy in patients with NCC without a history of seizures was significantly greater than in control subjects (P < 0.01) and tended to be even greater in patients with NCC with a history of seizures.
Conclusions: Hippocampal atrophy may not be exclusively related to seizure activity in patients with NCC. Other mechanisms, such as recurrent bouts of inflammation around calcified cysticerci, might explain the association between NCC and hippocampal atrophy
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Calcified Neurocysticercosis and Headache in an Endemic Village: A Case-Control Study Nested to a Population-Based Cohort
Headache in patients with calcified neurocysticercosis (NCC) is probably common but has been largely overlooked. We aimed to assess the presence, characteristics, and diagnosis of headache across patients with calcified NCC and their matched controls. In this case-control study nested to a population-based cohort, Atahualpa residents aged (3) 20 years with calcified NCC were identified as case patients and paired 1: 1 to age-and gender-matched randomly selected controls. A culturally adapted questionnaire was derived from the EUROLIGHT. Headache diagnosis was established according to the International Classification of Headache Disorders, 3rd edition. Conditional logistic regression models for matched paired data were fitted to assess the independent association between calcifiedNCC(as the exposure) and headache variables, after adjusting for education, alcohol intake, depression, and epilepsy. The selection process generated 106 case patients and their matched controls. Lifetime headache prevalence (odds ratio [OR]: 4.18; 95% Confidence Interval [CI]: 1.79-9.75; P = 0.001), current headaches (OR: 4.19; 95% CI: 1.92-9.16; P < 0.001), and intense headaches (OR: 9.47; 95% CI: 2.88-31.19; P < 0.001) were more frequent among cases than in controls. In addition, migraine (but not other forms of headache) was more frequent among subjects with calcified NCC (OR: 4.89; 95% CI: 2.36-11.39; P < 0.001). This study shows a robust epidemiological association between headache-particularly migraine-and calcified NCC