Radioecological assessment and radiometric dating of sediment cores from dynamic sedimentary systems of Pra and Volta estuaries (Ghana) along the Equatorial Atlantic.

The Volta and Pra estuaries (Ghana, West Africa) are dynamical sedimentary systems whose natural equilibrium is being affected by anthropogenic activities. This paper reports depth-distributions of 210Pb, 226Ra, 234Th, 40K, 228Ra and 137Cs for two sediment cores from these estuaries. Bulk densities were not steady-state and well correlated with 40K (p < 0.00005). Unsupported 210Pb profiles were incomplete, non-monotonic and showed large fluctuations. The assumptions involved in the common 210Pb-based dating models were not meet in these dynamical scenarios, and the use of 137Cs as a time-marker is difficult in Equatorial and South-Hemisphere countries due to its low fallout rates. Chronologies have been solved with the new 210Pb-based TERESA model, which operates with varying but statistically correlated fluxes and sediment accumulation rates (SAR). The core from the Volta reflects the conditions prevailing after the construction of the Akosombo Dam, with a mean SAR of 1.05 ± 0.03 g cm-2·y-1, while a higher value of 2.73 ± 0.06 g cm-2·y-1 was found in the Pra, affected by intense gold mining activities along its course. Radiological and radioecological assessments have been conducted by applying the UNSCEAR protocols and the ERICA model, respectively. The measured radionuclide concentrations do not pose any significant risk for the environment and human health.

Human brain microvascular endothelial cell traversal by Borrelia burgdorferi requires calcium signaling.

Neurological manifestations of Lyme disease (or neuroborreliosis) occur variably and while it is clear that Borrelia burgdorferi can invade the nervous system, how it does so is not well understood. Pathogen penetration through the blood brain barrier (BBB) is often influenced by calcium signaling in the endothelial cells triggered by extracellular host-pathogen interactions. We examined the traversal of B. burgdorferi across the human BBB using in vitro model systems constructed of human brain microvascular endothelial cells (HBMEC) grown on Costar Transwell inserts. Pretreatment of the cell monolayers with BAPTA-AM (an intracellular calcium chelator) or phospholipase C (PLC) inhibitor U73122 inhibited B. burgdorferi transmigration. By 5 h, BAPTA-AM significantly inhibited (82-99%; p <0.017) spirochete traversal of HBMEC compared to DMSO controls. Spirochete traversal was almost totally blocked (> or =99%; p <0.017) after pretreatment with the PLC-beta inhibitor U73122 as a result of barrier tightening based on electric cell-substrate impedance sensing (ECIS). The data suggest a role for calcium signaling in CNS spirochete invasion through endothelial cell barriers.

Anaplasma phagocytophilum-infected neutrophils enhance transmigration of Borrelia burgdorferi across the human blood brain barrier in vitro.

The manifestations of Lyme disease, caused by Ixodes spp. tick-transmitted Borrelia burgdorferi, range from skin infection to bloodstream invasion into the heart, joints and nervous system. The febrile infection human granulocytic anaplasmosis is caused by a neutrophilic rickettsia called Anaplasma phagocytophilum, also transmitted by Ixodes ticks. Previous studies suggest that co-infection with A. phagocytophilum contributes to increased spirochetal loads and severity of Lyme disease. However, a common link between these tick-transmitted pathogens is dissemination into blood or tissues through blood vessels. Preliminary studies show that B. burgdorferi binds and passes through endothelial barriers in part mediated by host matrix metalloproteases. Since neutrophils infected by A. phagocytophilum are activated to release bioactive metalloproteases and chemokines, we examined the enhanced B. burgdorferi transmigration through vascular barriers with co-infection in vitro. To test whether endothelial transmigration is enhanced with co-infection, B. burgdorferi and A. phagocytophilum-infected neutrophils were co-incubated with EA.hy926 cells (HUVEC-derived) and human brain microvascular endothelial cells in Transwell cultures. Transmigration of B. burgdorferi through endothelial cell barriers was determined and endothelial barrier integrity was measured by transendothelial electrical resistivity. More B. burgdorferi crossed both human BMEC and EA.hy926 cells in the presence of A. phagocytophilum-infected neutrophils than with uninfected neutrophils without affecting endothelial cell integrity. Such a mechanism may contribute to increased blood and tissue spirochete loads.

Metalloporphyrin mediated DNA cleavage by a low concentration of HaeIII restriction enzyme.

The plasmid DNA scission by the restriction enzyme HaeIII was investigated in the presence of tetrakis(1-methylpyridinium-4-yl)porphyrin (H2TMPyP) and its manganese(III), iron(III), nickel(II), cobalt(III) and zinc(II) derivatives. The effect of metalloporphyrins on plasmid DNA cleavage was ascertained by gel electrophoresis. UV-Vis absorption spectroscopy and circular dichroism (CD) spectroscopy. In the absence of the metalloporphyrins, plasmid DNA scission did not occur in the presence of a low concentration of HaeIII (0.2 units microL(-1)) at 37 degrees C after 1 h incubation. However, DNA cleavage occurred in the presence of the metalloporphyrins and HaeIII (0.2 units microL(-1)) at 37 degrees C after 1 h incubation. Gel electrophoresis results indicate the catalytic effect of metalloporphyrins (Mn(III)-, Fe(III)-, Co(III)- and Zn(II)TMPyP) by binding to both DNA and the enzyme through electrostatic interaction, which was confirmed by the change in UV-Vis and CD spectra. A mechanism for the enhanced DNA cleavage is proposed.

Evaluation of a commercial immunodiagnostic kit incorporating lipoarabinomannan in the serodiagnosis of pulmonary tuberculosis in Ghana.

UNLABELLED: We evaluated 'Mycodot', a commercially marketed immunodiagnostic test for tuberculosis which detects antibodies to lipoarabinomannan antigen. Serum was tested from 52 patients with newly diagnosed smear-positive pulmonary tuberculosis, of whom 20 were HIV-positive and 32 HIV-negative. Control sera were taken from 40 patients of whom 20 had acute non-tuberculous lobar pneumonia and 20 patients had no respiratory disease. The test was found to have a very high specificity of 97.5% (95% CI:92.5-100%). However, the sensitivity in HIV-negative patients was 56% (95% CI:39-73%), and was substantially lower at 25% (95% CI:6-44%) in HIV-positive patients. IN CONCLUSION: 'Mycodot' was found to be a highly specific and easily performed assay. However, the poor sensitivity, especially in HIV-infected patients, renders it unlikely to be useful either as a primary or adjunctive diagnostic test for tuberculosis, particularly in countries with a high prevalence of HIV. A larger trial of this assay in Ghana was not deemed necessary.

Current trends in the incidence of cerebrovascular accidents in Accra.

The incidence of cerebrovascular accidents (CVA) in Accra during three periods--1960-1968, 1976-1983, and 1990-1993, was compared. There was dramatic increase in the incidence between 1990-1993. Uncontrolled hypertension due to non-compliance with drug therapy seems to be the main cause. The economic plight of the people may explain the non compliance. The case fatality was between 41.9% to 50.3% for the years 1990-1993. Cardiovascular diseases, notably hypertension and CVA, have become the major causes of morbidity and mortality in Accra.

Manual of the National Tuberculosis Control Programme in Ghana

This is a manual of the National Tuberculosis Control Programme. It gives an account of what the disease is; modes of transmission; and ways to combat the disease