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Biomedical subjects

G Foster

Publications and source records attributed to G Foster.

At least 55 records · Page 3Linked to original sources

Isolation of translactone-containing triterpenes with thrombin inhibitory activities from the leaves of Lantana camara.

Methanolic extracts prepared from the leaves of Lantana camara have been found to inhibit human thrombin. An assay, in which thrombin activity is measured as a function of clot formation from fibrinogen, was used to guide the fractionation and purification of five principal active constituents (1-5), which were all characterized as 5,5-trans-fused cyclic lactone-containing euphane triterpenes.

Carbohydrate Sequence↗

A simple clinical model for the diagnosis of deep-vein thrombosis combined with impedance plethysmography: potential for an improvement in the diagnostic process.

OBJECTIVES: We recently demonstrated the utility of a clinical model combined with ultrasonography to assist the diagnostic approach in patients with suspected deep-vein thrombosis (DVT). In this study we also sought to demonstrate that the model is useful with impedance plethysmography, a less accurate and less utilized diagnostic test. The original clinical model is slightly cumbersome to use; thus at the completion of the study we attempted to develop a simpler scoring system with a goal of maintaining accuracy. DESIGN: An open, nonrandomized, multicentre trial. SETTING: Three centres, two in Canada, and one in Italy. SUBJECTS: Ambulatory patients with suspected deep-vein thrombosis. INTERVENTIONS: All patients were assessed clinically to determine the probability for deep-vein thrombosis prior to performing impedance plethysmography and venography. We compared the accuracy of impedance plethysmography between the three pretest probability categories of high, moderate and low. All of the above were performed and interpreted by independent observers. When the study was completed, we revised the clinical model by first performing a simple regression analysis then a multiple logistic regression analysis; a scoring system was devised using the latter. RESULTS: Impedance plethysmography is significantly more sensitive and less specific for all DVT in patients with high pretest probability for deep-vein thrombosis (P = 0.001). The post- test probability (positive predictive value) for deep-vein thrombosis with an abnormal impedance plethysmography result was significantly different (P = 0.0001) between the three pretest probability categories. Multiple regression analysis has provided a new model with only nine variables and a simple scoring system. The retrospective application of the revised clinical model, which is simpler to use, suggests it will provide similar results as the original clinical model when combined with impedance plethysmography. The combination of impedance plethysmography and the clinical model suggests patients are likely to have false positive results if they have a low or moderate pretest probability for deep-vein thrombosis and false negative results if the pretest probability is high. The combination of a low pretest probability and a normal impedance plethysmography result may exclude the need for serial testing, and represented more than 50% of our patient population. CONCLUSIONS: The use of the clinical model in conjunction with impedance plethysmography would decrease the number of false positive and negative diagnoses and could markedly decrease the need for serial impedance plethysmography. Combining the clinical model with impedance plethysmography could overcome the fact that impedance plethysmography is clearly less accurate than venous ultrasound imaging. The use of the revised clinical model may increase acceptability and utility, but prospective testing is required before widespread use.

Diagnosis, Differential↗

Isolation of Escherichia coli O86:K61 producing cyto-lethal distending toxin from wild birds of the finch family.

Escherichia coli was recovered from selected tissues of 43 out of a total of 46 finches found dead in the Scottish Highlands during April-May of 1994 and 1995. The isolates did not ferment sorbitol, rhamnose, sucrose or melibiose; they belonged to serogroup O86:K61, produced cytolethal distending toxin (CLDT) and possessed the eae gene sequence. The consistent recovery of organisms producing CLDT and possessing the eae gene suggests that these organisms may have played a significant role in the finch mortalities.

Adhesins, Bacterial↗

Cardiovascular disease risk factors are lower in African-American vegans compared to lacto-ovo-vegetarians.

OBJECTIVE: This study was undertaken to determine if African-American strict vegetarians (vegans) exhibit lower blood pressure (BP) and a more favorable serum lipid profile than their lacto-ovo vegetarian (LOV) counterparts, and if plasma ascorbic acid (AA) concentrations could explain any group differences in these cardiovascular disease (CVD) risk factors. METHODS: Habitual dietary intake, anthropometric characteristics, blood pressure, and blood lipids and ascorbic acid concentrations were determined in African-American study participants (male vegans, n = 14, age = 45.6 years; male LOV, n = 49, age = 49.8; female vegans, n = 31, age = 51.1, female LOV, n = 94, age = 52.1) recruited from Seventh-Day Adventist Churches in several cities in the northeastern United States. RESULTS: Body mass index (BMI) was significantly lower in the vegans (24.7 +/- 1.9 kg/m2) compared to LOV (26.4 +/- 0.45 kg/m2). There were no diet or gender differences in BP. Serum total cholesterol (3.75 +/- 0.12 vs. 4.51 +/- 0.10 mmol/L), LDL-cholesterol (2.06 +/- 0.13 vs. 2.65 +/- 0.09 mmol/l), and triglycerides (0.94 +/- 0.07 vs. 1.17 +/- 0.04 mmol/L) were significantly (p < 0.05) lower in vegans compared to LOV, but there were no dietary group differences in HDL-C. The ratio of total to HDL-cholesterol was significantly lower in vegans than in LOV (3.0 +/- 0.13 vs. 3.7 +/- 0.13). There were no dietary group differences in plasma AA concentrations. However, in the entire sample, plasma AA was inversely associated with BP (SBP: r = -0.46, p < 0.001, DBP: r = -0.32, p < 0.001), but unrelated to the serum lipid concentrations. CONCLUSION: African-American vegans exhibit a more favorable serum lipid profile than lacto-ovo-vegatarians and plasma AA is inversely related to BP in African-American vegetarians but does not explain any of the differences in CVD risk factors between vegans and lacto-ovo vegetarians.

Anthropometry↗

Strategies for providing care and support to children orphaned by AIDS.

As a result of the severe HIV/AIDS epidemic in sub-Saharan countries such as Zimbabwe, where between 25-30% of the adult population are estimated to be infected, there are a growing number of orphans requiring care and support. Traditionally, orphans have been absorbed within the extended family but this is becoming more difficult because of the large number of young adults dying. The burden of care and support is falling on the very young and the very old. A number of strategies have been introduced to provide this care and support. Institutions, though popular, are very expensive to run, have limited capacity and only really cater for physical needs. Interventions which simply react to those who present to them may not reach the most needy and may encourage dependency. Community-based orphan care has been identified as the best and most cost-effective way of caring for orphans. An example of a community-based orphan visiting programme is presented. In the last six months of 1996, the FOCUS programme's 88 volunteers made a total of 9,634 visits to 3,192 orphans in 798 families at an average cost of US+1.55 per visit. The key elements of such programmes have been identified. They need to be implemented by a community-based organization (CBO) within a defined community. Volunteers should be selected from within the community. They need to be trained and supported as they enumerate orphans, identify the most needy and carry out regular visits. The volunteers should keep records of all their activities. These records can then be used as a basis for monitoring the programme. In order to cope with the increasing number of orphans in resource-poor settings like Zimbabwe, it is essential that such programmes be replicated and scaled up. This not only an economic necessity but is also a way of providing appropriate and effective services to those who need them.

Child↗

Today's children--challenges to child health promotion in countries with severe AIDS epidemics.

Recent declines in infant and child mortality rates (IMR and CMR) are being reversed due to AIDS. Greatest impacts are in southern African countries with severe HIV epidemics and lower non-AIDS IMR/CMR. Zimbabwe and Zambia's IMR were estimated to be 40% and 30% higher in 1996; CMR by 2010 was projected to increase fourfold in Zimbabwe, threefold in Botswana and to double in Kenya and Zambia due to AIDS. HIV indirectly impacts children through orphanhood, TB and poverty. By 1996, life expectancy fell to 36 in Zambia, 42 in Zimbabwe and 40 in Uganda. One-third of children may become vulnerable after maternal orphanhood since elderly and juvenile caregivers are frequently uninformed about nutrition, oral rehydration, immunization and diagnosing serious illness. Resurgence of adult and paediatric TB affects children through increasing orphanhood and increased child mortality. AIDS-induced poverty among survivors leads to deterioration in children's health and increased vulnerability of adolescent survivors to HIV infection. The situation is set to worsen, especially in communities experiencing the cumulative impact of repeated parental deaths. Reducing the number and vulnerability of children and adolescents becoming HIV infected and increasing support to affected children are important strategies to improve child health in countries with severe epidemics.

AIDS-Related Opportunistic Infections↗

Corynebacterium phocae sp. nov., isolated from the common seal (Phoca vitulina).

Phenotypic and phylogenetic studies were performed on four strains of a Gram-positive non-acid-fast coryneform-like organism isolated from the nasal cavities of common seals (Phoca vitulina). Chemotaxonomic investigations revealed the presence of corynomycolic acids in the unidentified isolates, which is consistent with corynebacteria. 16S rRNA gene sequence analysis demonstrated that the strains from seals represent a hitherto unknown subline within the genus Corynebacterium sensu stricto. Based on the results of the phylogenetic analysis and phenotypical criteria, it is proposed that the bacterium should be classified as a new species, Corynebacterium phocae. The type strain of Corynebacterium phocae is CCUG 38205T.

Animals↗

Actinobacillus scotiae sp. nov., a new member of the family Pasteurellaceae Pohl (1979) 1981 isolated from porpoises (Phocoena phocoena).

Phenotypic and phylogenetic studies were performed on a Gram-negative, rod-shaped bacterium isolated from three porpoises. Biochemical and physiological studies indicated that the bacterium was related to the family Pasteurellaceae. Comparative 16S rRNA gene sequencing studies confirmed these findings and demonstrated that the bacterium represents a hitherto unknown subline. The nearest phylogenetic relative of the unknown bacterium was Actinobacillus delphinicola, an organism also originating from sea mammals, although a sequence divergence of 3% demonstrated that the newly isolated bacterium is a distinct species. On the basis of the results of the phylogenetic analysis and phenotypic criteria, it is proposed that the bacterium should be classified as a new species, Actinobacillus scotiae sp. nov. The type strain of Actinobacillus scotiae sp. nov. is NCTC 12922T (= M2000/95/1T).

Actinobacillus↗

The characterisation of Brucella strains isolated from marine mammals.

Small Gram negative coccobacilli isolated from seals, porpoises, dolphins and from an otter road casualty were identified as Brucellae by their colonial and cell morphology, staining characteristics, biochemical activity, agglutination by monospecific antisera and susceptibility to lysis by Brucella specific bacteriophage. Their characterisation, including metabolic profiles, is described. These strains could not be assigned to recognised nomen species of the genus Brucella and it is suggested that they comprise a new nomen species to be called B. maris (sp. nov., type strain 2/94). It is further suggested the nomen species be subdivided into three biovars corresponding to their CO2 requirement, metabolic activity on galactose, dominant antigen and animal host.

Animals↗

Identification of a subpopulation of human renal microvascular endothelial cells with capacity to form capillary-like cord and tube structures.

Endothelial specialization is a prominent feature within distinct capillary beds of organs such as mammalian kidney, yet immunological markers for functionally distinct subpopulations of cultured endothelial cells from tissue sources such as kidney have not been available. We developed a simple and reproducible isolation and culture procedure to recover human renal microvascular endothelial cells (HRMEC) from the cortex of unused donor kidneys. This procedure yields highly purified preparations of cells that display endothelial markers that include Factor VIII antigen, acetyl-LDL receptors, and determinants that bind Ulex europaeus lectin. HRMEC assemble into capillary-like cord and tube structures when plated on the surface of basement membrane-like matrix (BMM) in media containing phorbol myristate acetate. To further define subpopulations of HRMEC, we generated a panel of monoclonal antibodies and screened for those recognizing cell surface determinants. One monoclonal antibody recovery from this screen recognized a cell surface protein expressed on a subpopulation of HRMEC that we have designated PEC-1 (pioneer endothelial cell antigen-1). Cells expressing PEC-1 extended long, interconnecting filopodial processes in response to phorbol myristate acetate and assembled into capillary-like structures when plated on BMM. Anti-PEC-1 immunoprecipitated proteins of 25 and 27 kDa. Magnetic bead separation of PEC-1 (+) cells selected cells that assemble into capillary-like cord and tube structures. The remaining PEC-1 (-) HRMEC population formed matrix adherent patches. In the kidney, the PEC-1 determinant is expressed on a small subpopulation of microvascular glomerular cells and is prominently expressed on the apical membrane of proximal tubule cells. The PEC-1 determinant discriminates among subpopulations of HRMEC, identifying a subpopulation that contributes to assembly of capillary-like structures.

Adult↗

Perceptions of children and community members concerning the circumstances of orphans in rural Zimbabwe.

Focus group discussions and interviews were held with 40 orphans, 25 caretakers and 33 other community workers from a rural area near Mutare, Zimbabwe. Orphan concerns included feeling different from other children, stress, stigmatization, exploitation, schooling, lack of visits and neglect of support responsibilities by relatives. Many community members, while recognizing their limitations due to poverty, were already actively helping orphans and caretakers. Extended family networks are the primary resource for orphans, though some relatives exploit orphans or fail to fulfil their responsibilities. Interventions are suggested which support community coping mechanisms by strengthening the capacities of families to care for orphans. Outside organizations can develop partnerships with community groups, helping them to respond to the impact of AIDS, by building upon existing concern for orphan families. They can help affected communities to develop orphan support activities which encourage caring responses by community leaders and relatives and which discourage property-grabbing and orphan neglect. Material support channelled through community groups to destitute families at critical times can strengthen family coping mechanisms. Income-generating activities should build upon communities' existing capabilities and benefit the most vulnerable orphan households. Some communities are responding to the AIDS disaster by adaptations to cope with devastating changes taking place in their communities.

Acquired Immunodeficiency Syndrome↗

Phylogenetic analysis of the genus Actinomyces based on 16S rRNA gene sequences: description of Arcanobacterium phocae sp. nov., Arcanobacterium bernardiae comb. nov., and Arcanobacterium pyogenes comb. nov.

A systematic phylogenetic analysis of the genus Actinomyces was performed. The 16S rRNA gene sequences of 13 Actinomyces species, an unnamed Actinomyces strain (ATCC 49338), and an Actinomyces-like isolate from sea mammals were determined. Comparative sequence analysis with closely related taxa revealed phylogenetic diversity and internal structure within the genus Actinomyces. In addition, some members of other genera (viz., the genera Arcanobacterium, Mobiluncus, and Rothia) were shown to be phylogenetically intermixed with the Actinomyces species. It was evident from both distance and tree topology considerations that the genus Actinomyces is in urgent need of taxonomic revision and requires subdivision into several genera. Based on the results of the present study it is proposed that Actinomyces bernardiae and Actinomyces pyogenes be assigned to the genus Arcanobacterium as Arcanobacterium bernardiae comb. nov. and Arcanobacterium pyogenes comb. nov., respectively. In addition, a new species, Arcanobacterium phocae, is proposed for Actinomyces-like bacteria isolated from seals.

Actinomycetaceae↗

Staphylococcus lutrae sp. nov., a new coagulase-positive species isolated from otters.

Phenotypic and phylogenetic studies were performed with three strains of a catalase-positive, gram-positive, coccus-shaped bacterium isolated from otters. The results of a 16S rRNA gene sequence analysis demonstrated that these strains represent a hitherto unknown subline within the genus Staphylococcus. Based on the results of the phylogenetic analysis and phenotypic criteria, we propose that these bacteria should be classified as members of a new species, Staphylococcus lutrae. The type strain of S. lutrae is DSM 10244.

Animals↗

Estimating coverage of a community-based home care programme.

The Family AIDS Caring Trust (FACT) was formed in Mutare, Zimbabwe's third largest city, in 1987. FACT's home care programme started in 1992. The programme operates in the urban area of Mutare which contains three townships with a population of 131,367. The area employs a trained nurse as a coordinator and four assistants, each assigned a zone within the city, who carry out the bulk of the visits. As part of an evaluation of the programme we attempted to estimate its coverage using different models. Using these models the FACT programme has a coverage of between 2.5%-23%. It is important that all home care programmes think in terms of coverage and do not simply strive to provide high quality services to a few patients.

Acquired Immunodeficiency Syndrome↗