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PubMed2006

A second RGD motif in the 1D capsid protein of a SAT1 type foot-and-mouth disease virus field isolate is not essential for attachment to target cells.

The amino acid sequence motif Arg-Gly-Asp (RGD), located in the surface-exposed betaG-betaH loop of the 1D protein of different serotypes and subtypes of foot-and-mouth disease virus (FMDV), is highly conserved and participates in binding of FMDV to susceptible cells. Previous sequence analyses of the 1D-encoding region of a FMDV serotype SAT1 field isolate from Namibia (NAM/307/98) indicated the presence of a second RGD motif upstream of the conserved betaG-betaH loop RGD. The role of these RGD sequences in virus infection was investigated by mutating the betaG-betaH loop RGD to a KGE tripeptide, using a genome-length infectious chimeric cDNA clone. Although the infectivity of the derived mutant viruses for baby hamster kidney cells (BHK-21) was lost, subsequent replacement of the KGE sequence with RGD in the mutant cDNA clone led to recovery of infectious viruses. Furthermore, viral RNA replication could be demonstrated with the genetically engineered mutant and non-mutant viruses. The presence of virus particles in the transfected cells could be also demonstrated by electron microscopy. These results demonstrate that, in contrast to the betaG-betaH loop RGD motif, the second RGD sequence in the capsid protein 1D of NAM/307/98 does not function as a ligand for receptor binding in BHK-21 cells.

Amino Acid Motifs↗
PubMed1998

Geographic variations in the composition of ivory of the African elephant (Loxodonta africana).

Tracing the source of origin of illegal ivory will contribute to the identification of poorly managed game parks and facilitate steps taken to prevent the African elephant from becoming extinct. This study was aimed at establishing a database on the composition of ivory obtained from elephant sanctuary areas in Southern Africa. Fragments of elephant ivory from seven geographically distinct areas in South Africa, Namibia and Botswana were analysed for inorganic and organic content. A total of 20 elements was detected in the inorganic fraction of ivory, some in concentrations as low as 0.25 microg/g. The concentrations of calcium, phosphate, magnesium, fluoride, cobalt and zinc showed statistically significant differences (p < 0.007) between ivory obtained from different regions. Analyses of the organic fraction identified 17 amino acids. Ivory from arid regions showed significantly lower proline plus hydroxyproline content and under-hydroxylation of lysine residues. This study indicates that chemical analyses of ivory could be beneficial in tracing the source of illegal ivory.

Africa, Southern↗
PubMed2000

Molecular investigation of African isolates of Trichinella reveals genetic polymorphism in Trichinella nelsoni.

Molecular genetic studies were carried out on three isolates of Trichinella nelsoni (from Kenya, Tanzania and South Africa) and three isolates of Trichinella T8 (from South Africa and Namibia) from sylvatic carnivores and from a sylvatic swine. A probe (pT7.3) specific for T. nelsoni was obtained by screening a pUC18 genomic library. The pT7.3 sequence was 346 bp in length with an AT content of 70%. The sequence is present approximately 200 times per haploid genome. Southern blot analysis of Hind III digested DNAs of the three isolates of T. nelsoni revealed that the hybridisation patterns of the isolates from Kenya and Tanzania were identical and that they differed from that of the isolate from South Africa, indicating the presence of polymorphism in this species. A pUC18 genomic library of Trichinella T8 was also screened, and one clone (pT8.3) was found to be specific for homologous DNA by dot blot, but Southern blot analysis of DNA samples from eight genotypes showed different hybridisation signals for both Trichinella T8 and Trichinella britovi DNAs. No differences in the nucleotide sequences of the expansion segment V were observed for the T. nelsoni isolates. However, they differed from those of Trichinella T8. The presence of Trichinella T8 in Africa south of the Sahara and its genetic relationship with T. britovi remain unclear and warrant detailed investigations.

Animals↗
PubMedDate not supplied

Genetic heterogeneity in the species Leishmania tropica revealed by different PCR-based methods.

A PCR fingerprinting approach, using single non-specific primers, as well as restriction and single-strand conformation polymorphism (SSCP) analyses of the amplified ribosomal internal transcribed spacer, were used to investigate genetic variability in the species Leishmania tropica. Twenty-nine strains of the 'L. tropica complex' from different Old World geographical areas were studied including 4 from Namibia, and 1 strain of L. killicki. All techniques revealed a high degree of genetic heterogeneity among the strains of L. tropica. The PCR fingerprinting displayed the highest discriminatory power, but can be applied only to cultured parasites. The internal transcribed spacer (ITS) region can be amplified directly from infected clinical samples and analysed subsequently. No strict correlation was discerned between the genetic variants and either the geographical origin of the strains or the clinical manifestations associated with human disease, except for the Namibian strains. Also, genetic variation did not correlate well with characterization by enzyme variant electrophoretic analysis. The strain of L. killicki always clustered together with the strains of L. tropica, suggesting it, probably, should not be considered a separate species of Leishmania. However, the 4 Namibian strains formed a distinct, statistically well-supported group closely related to but different from the other strains of L. tropica.

Animals↗
PubMedDate not supplied

Where is the meningitis belt? Defining an area at risk of epidemic meningitis in Africa.

Mapping an area at risk of epidemics of meningococcal meningitis in Africa has significant implications for their prevention and case treatment, through the targeted development of improved surveillance systems and control policies. Such an area was described using information obtained from published and unpublished reports of meningitis epidemics between 1980 and 1999 and cases of meningococcal disease reported by surveillance systems to WHO. The Sahel bore the greatest epidemic burden, with over two-thirds of documented outbreaks and high attack rates. In addition to those already in the Meningitis Belt, countries affected included Guinea-Bissau, Guinea, Côte d'Ivoire, Togo, the Central African Republic and Eritrea. Elsewhere epidemics were reported from a band of countries around the Rift Valley and Great Lakes regions extending as far south as Mozambique and from here west to Angola and Namibia in southern Africa. The cumulative pan-continental analysis provided evidence of an epidemic-susceptible area which extends beyond the region accepted as the Meningitis Belt and which, moreover, may be partially determined by the physical environment, as shown by a striking correspondence to the 300-1100-mm mean annual rainfall isohyets.

Africa↗
PubMed2004

Evaluation of a species-specific PCR assay for the Anopheles funestus group from eleven African countries and Madagascar.

A newly published cocktail polymerase chain reaction (PCR) assay can identify five members of the Anopheles funestus group: An. funestus, An. vaneedeni, An. parensis, An. leesoni and An. rivulorum. The assay was evaluated on specimens from 11 African countries: Angola, Cote d'Ivoire, Ethiopia, Kenya, Malawi, Mozambique, Namibia, South Africa, Tanzania, Uganda and Zambia; and the island of Madagascar. The polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) and the internal transcribed spacer PCR (ITS2-PCR) assays were used as a priori identification methods on 900 specimens. Of these, 96.4% were correctly identified using the new cocktail PCR method. The remaining 3.5% (32) from Malawi failed to amplify. The failure to identify these samples was not significantly different from the samples from the other countries (Chi-square; P > 0.05). The results suggest that the new species-specific PCR assay is an efficient and effective means of identifying 5 members of the An. funestus group in a single reaction. It is also less time-consuming than the molecular methods previously used on the group.

Africa↗
PubMedDate not supplied

Distribution and levels of eight toxaphene congeners in different tissues of marine mammals, birds and cod livers.

Levels and distribution of eight compounds of technical toxaphene (CTTs) were determined in different marine species (seals, cetaceans, birds, and fish). The eight CTTs included six commercially available and two chlorobornanes prepared in our lab. These congeners were present in all investigated samples. In agreement with earlier studies, the octachlorobornane B8-1413 (P-26) and the nonachlorobornane B9-1679 (P-50) were the most abundant congeners in most of the samples. In seal blubber, B8-1413 (P-26) and B9-1679 (P-50) contributed with up to approximately 80% (Weddell seal) to the sum of the eight CTTs. In seals from the northern hemisphere the nonachlorobornane was more abundant while in those from the southern hemisphere (Antarctic and Namibia), the octachlorobornane B8-1413 (P-26) usually appeared at higher concentrations. Depending on the species the contribution of the other congeners varied significantly. B9-1025 (P-62) ranged from 2-20%, B8-1412 was found at 4-25% with highest contribution in birds, and B8-2229 (P-44) was found at 5-15%. The remaining three congeners B7-1453, B8-1414 (P-40), and B8-1945 (P-41) were lower abundant except B8-1414 (P-40) which was found at high contribution in liver and kidney of birds. The sum of the eight CTTs ranged from 4 microg/kg to 1.4 mg/kg, depending on the species and region. In most of the seal blubber samples, PCBs and DDT were more abundant (factor 2-20) but Antarctic Weddell seals showed higher CTT levels than PCBs and DDT.

Adipose Tissue↗
PubMed2002

Meeting international goals in child survival and HIV/AIDS.

BACKGROUND: After a decade of focused efforts to reduce under-5 mortality results have been mixed, with the HIV/AIDS epidemic often used to explain reversing trends. We investigated this assumption by estimating HIV-attributable under-5 mortality in 39 countries in sub-Saharan Africa and comparing it to total mortality in children younger than 5 years between 1990 and 1999. METHODS: Annual HIV-attributable under-5 mortality was estimated in a four-step process with previously obtained data from antenatal clinics in 39 countries based on HIV sero-prevalence among pregnant women. This process produced estimates of: the number of children born to HIV-infected women; the number of children infected via mother-to-child-transmission of HIV; the number of HIV-infected children who died before age 5 years; and the number of HIV-infected children who died before age 5 years adjusted for competing causes of mortality. FINDINGS: An estimated 330,000 children younger than age 5 years died in sub-Saharan Africa in 1999 with HIV infection. When corrected for competing causes of mortality, HIV infection caused 7.7% of under-5 deaths in 1999, a significant rise from 2% in 1990. Five countries (Botswana, Namibia, Swaziland, Zambia, and Zimbabwe) have rates of HIV-attributable under-5 mortality of above 30 per 1000. An additional 16 countries have HIV-specific under-5 mortality rates between 10 and 25 per 1000. The remaining 18 countries have rates under 10 per 1000. INTERPRETATION: HIV/AIDS is an increasingly important cause of under-5 mortality in Africa. However, in many African countries, slowing or reversal of trends in child mortality cannot be explained by HIV alone. To meet international goals for reductions in child mortality, efforts must continue to focus on HIV/AIDS, but must also strengthen health systems that can deliver available interventions for the other major killer diseases of children in the developing world.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Prevalence of intimate partner violence: findings from the WHO multi-country study on women's health and domestic violence.

BACKGROUND: Violence against women is a serious human rights abuse and public health issue. Despite growing evidence of the size of the problem, current evidence comes largely from industrialised settings, and methodological differences limit the extent to which comparisons can be made between studies. We aimed to estimate the extent of physical and sexual intimate partner violence against women in 15 sites in ten countries: Bangladesh, Brazil, Ethiopia, Japan, Namibia, Peru, Samoa, Serbia and Montenegro, Thailand, and the United Republic of Tanzania. METHODS: Standardised population-based household surveys were done between 2000 and 2003. Women aged 15-49 years were interviewed and those who had ever had a male partner were asked in private about their experiences of physically and sexually violent and emotionally abusive acts. FINDINGS: 24,097 women completed interviews, with around 1500 interviews per site. The reported lifetime prevalence of physical or sexual partner violence, or both, varied from 15% to 71%, with two sites having a prevalence of less than 25%, seven between 25% and 50%, and six between 50% and 75%. Between 4% and 54% of respondents reported physical or sexual partner violence, or both, in the past year. Men who were more controlling were more likely to be violent against their partners. In all but one setting women were at far greater risk of physical or sexual violence by a partner than from violence by other people. INTERPRETATION: The findings confirm that physical and sexual partner violence against women is widespread. The variation in prevalence within and between settings highlights that this violence in not inevitable, and must be addressed.

Adolescent↗
PubMed2002

Polymorphic expression in the CD8alpha chain surface receptor of African lions (Panthera leo).

Free-ranging African lion (Panthera leo) peripheral blood mononuclear cells (PBMC) were examined using flow cytometry and antibodies developed for use in the domestic cat to determine if phenotypic changes occurred in lion lymphocytes as a result of feline immunodeficiency virus (FIV) infection. The percentage of CD8 cells from lion peripheral blood was considerably lower than in the domestic cat. Lions with elevated levels of CD8+ cells were typically infected with FIV, similar to observations in the domestic cat. Antibodies against the alpha chain of the CD8 receptor (monoclonal antibody (mAb) 3.357) did not react consistently in all lions examined. Flow cytometric analysis determined that approximately 82 and 80% of the animals from Kruger and Hluhluwe-Umfolozi National Parks in South Africa reacted with the monoclonal antibody against the alpha chain of CD8 receptor, while only 17% of the lions in Etosha National Park in Namibia cross-reacted with the CD8alpha chain. There was no apparent correlation between FIV status and CD8alpha chain reactivity. The relative isolation of Etosha from the other two parks could explain the marked difference in CD8alpha chain expression and suggests that lions similar to other mammalian species demonstrate polymorphic expression of the CD8alpha chain (197).

Africa, Southern↗
PubMed1999

Radiation therapy in Africa: distribution and equipment.

BACKGROUND AND PURPOSE: Africa is the least developed continent as regards radiation oncology resources. The documented ASR of cancer is of the order of 1 to 2 per 1000. With improving health care this is becoming more significant. This review was undertaken to help develop priorities for the region. MATERIALS AND METHODS: Radiation Oncology departments in Africa were identified and a survey of their equipment performed. These were compared to the reported situation in 1991. Population tables for the year 2000 were compared to available megavoltage machines. RESULTS: Of 56 countries in Africa, only 22 are confidently known to have megavoltage therapy concentrated in the southern and northern extremes of the continent. The 155 megavoltage machines operating represents over 100% increase over the past 8 years. The population served by each megavoltage machine ranges from 0.6 million to 70 million per machine. Overall, only 50% of the population have some access to Radiation Oncology services. CONCLUSION: Progress has been made in initiating radiation oncology in Ghana, Ethiopia and Namibia. There has been some increase in machines in Algeria, Egypt, Libya, Morocco and Tunisia. However, a large backlog exists for basic radiation services.

Africa↗
PubMed2003

Phylogenetic analysis of the erythrocytic Anaplasma species based on 16S rDNA and GroEL (HSP60) sequences of A. marginale, A. centrale, and A. ovis and the specific detection of A. centrale vaccine strain.

Phenotypic criteria for the identification of erythrocytic ruminant Anaplasma species has relied on subjective identification methods such as host pathogenicity (virulence for cattle or sheep) and/or the location of Anaplasma inclusion bodies within the host's red cells. Sequence comparisons of new and available GenBank Accessions were investigated to elucidate the relationships among these closely related Anaplasma species. Twenty-one 16S rDNA and GroEL (HSP60) sequences from 13 Anaplasma marginale (South Africa, Namibia, Zimbabwe, Israel, USA, Australia and Uruguay), three A. centrale (South Africa and Japan), two A. ovis (USA and South Africa), and two unknown Anaplasma species isolated from wild ruminants (South Africa), were compared. 16S rDNA maximum-likelihood and distance trees separated all A. marginale (and the two wild ruminant isolates) from the two South African A. centrale (including original vaccine strain, Theiler, 1911). The Japanese A. centrale (Aomori) demonstrated the lowest sequence identity to the remaining erythrocytic Anaplasma species. A. ovis inter-species relationships could not be resolved through the 16S rDNA analyses, whereas strong bootstrap branch support is demonstrated in the GroEL distance tree using A. ovis OVI strain. All erythrocytic Anaplasma species and isolates were confirmed to belong to the same cluster showing strong branch support to Anaplasma (Ehrlichia) phagocytophilum with Ehrlichia (Cowdria) ruminantium and Rickettsia rickettsii serving as appropriate out-groups. Based on groEL sequences, a specific PCR method was developed which amplified A. centrale vaccine (Theiler, 1911) specifically. This study confirms the suitability of 16S rDNA sequences to define genera and demonstrates the usefulness of GroEL sequences for defining species of erythrocytic Anaplasma.

Anaplasma↗
PubMed1992

Onyalai.

Onyalai is an acquired form of immune thrombocytopenia which differs clinically, epidemiologically and immunologically from idiopathic thrombocytopenic purpura (Table 4). The clinical hallmark is haemorrhagic bullae on the mucosa of the oronasopharynx. Haemorrhage from ruptured bullae, epistaxis or gastrointestinal bleeding is severe and may cause shock and death. The disease is limited to some black populations of central southern Africa, with a recorded incidence of one per 660 inhabitants per year in the Kavango territory of Namibia. The majority of patients demonstrate both IgG and IgM serum platelet antibodies and serum platelet glycoprotein IIb/IIIa autoantibodies. Chronic thrombocytopenia often ensues and recurrent episodes of clinical bleeding are common. Treatment directed at the prevention of haemorrhagic shock reduced the mortality rate in the acute phase from 9.8 to 2.8%. Standard dose prednisolone does not increase the platelet count. Vincristine sulphate may benefit some patients and splenectomy is indicated in patients with severe uncontrollable haemorrhage. High dose intravenous gammaglobulin may be followed by a rise in the platelet count and cessation of haemorrhage. The aetiology is unknown. The possible aetiological role of mycotoxins from contaminated millet, sorghum or maize requires further investigation.

Africa↗
PubMed2001

Spouses' socioeconomic characteristics and fertility differences in sub-Saharan Africa: does spouse's education matter?

Although the general objective of this study is to examine the extent to which spouses' socioeconomic characteristics determine whether modern contraception is used and whether family limitation (the demand for no more children) is desired, its central goal is to evaluate the degree to which the net effect of a woman's education on those fertility decisions is altered once a control is made for the level of schooling of the husband. Individual characteristics of spouses included as controls in this analysis are on the one hand women's attributes relating to employment, age, parity, ethnic identity, and urban residence and, on the other hand, the occupation of the husband. Data used in this research are provided by DHS surveys conducted in fourteen sub-Saharan countries: Mali. Burkina Faso, Niger, Nigeria, Cameroon, Benin, Senegal. Ghana, Central African Republic, Kenya, Zambia, Zimbabwe, Namibia and Rwanda. With two dichotomous outcome variables, logistic regression was used to estimate two nested models for each dependent variable and for each country covered by the study. DHS respondents used as units of analysis in this study are women who were married (any kind of union) and non-pregnant at the time when each national survey was conducted. The findings suggest that, while an educated wife needs the support of an educated husband to state a preference for family limitation in contemporary sub-Saharan Africa, controlling for husband's education and other relevant covariates does little to undermine the evidence that woman's advanced education and the adoption of modern family planning are positively related in the developing world.

Africa South of the Sahara↗
PubMed1992

Genetic relationships between southern African SAT-2 isolates of foot-and-mouth-disease virus.

Sequencing of part of the 1D gene of foot-and-mouth disease virus was used to determine the relationships between SAT-2 viruses isolated from outbreaks which occurred in cattle in Zimbabwe and Namibia and in impala in South Africa between 1979 and 1989. The results demonstrated that the outbreaks in different countries were unrelated. Surprisingly close relationships were shown between all SAT-2 viruses isolated from cattle in Zimbabwe since 1983 but the two major epizootics which occurred in 1989 were caused by viruses which were clearly different. Conversely, two apparently unrelated outbreaks in impala in South Africa were caused by viruses which could not be distinguished.

Africa, Southern↗
PubMed2000

Namibian chewing stick, Diospyros lycioides, contains antibacterial compounds against oral pathogens.

The twigs of Diospyros lycioides, a plant commonly known as "muthala", are frequently used as chewing sticks for the cleaning of teeth by rural and urban people in Namibia. Preliminary studies showed that a methanol extract of D. lycioides inhibited growth of selected oral pathogens. Subsequent bioassay-guided fractionation led to the isolation of four novel bioactive naphthalene glycosides, diospyrosides A, B, C, and D (1-4), and two known bioactive naphthoquinones, juglone (5) and 7-methyljuglone (6). The structures of the new compounds were elucidated using spectroscopic techniques including 1D and 2D NMR. These compounds inhibited the growth of oral cariogenic bacteria (Streptococcus mutans and Streptococcus sanguis) and periodontal pathogens (Porphyromonas gingivalis and Prevotella intermedia) at minimum inhibitory concentrations ranging from 0.019 to 1.25 mg/mL. Juglone exhibited the strongest inhibitory activity among these compounds.

Anti-Bacterial Agents↗
PubMed1998

Binaphthalenone glycosides from African chewing sticks, Diospyros lycioides.

Our laboratory has engaged in the exploration of active antimicrobial principles present in chewing sticks commonly used by the African and Middle Eastern countries as a mechanical oral hygiene aid in place of tooth brushing. During this investigation, a methanol extract from the twigs of Diospyros lycioides, a Namibia tooth cleaning stick, demonstrated antimicrobial activity against common oral pathogens including Streptococcus mutans and Porphyromonas gingivalis (MICs 2.5 and 0.156 mg/mL). Subsequent fractionation and purification of this extract led to the identification of two novel binaphathalenone glycosides: 1', 2-binaphthalen-4-one-2',3-dimethyl-1,8'-epoxy-1,4',5,5',8, 8'-hexahydroxy-8-O-beta-glucopyranosyl-5'-O-beta-xylopyranosyl(1-- >6) -beta-glucopyranoside (1) and 1',2-binaphthalen-4-one-2', 3-dimethyl-1,8'-epoxy-1,4',5,5',8,8'-hexahydroxy-5', 8-di-O-beta-xylopyranosyl(1-->6)-beta-glucopyranoside (2). Their structures were established using spectroscopic techniques. Examination of the antimicrobial activity of these two compounds revealed positive but only marginal growth inhibition against the test cariogenic pathogens, S. sanguis and Streptococcus mutans.

Anti-Bacterial Agents↗
PubMed2000

Transient high temperatures in mantle plume heads inferred from magnesian olivines in Phanerozoic picrites.

Both scaled laboratory experiments and numerical models of terrestrial mantle plumes produce 'balloon-on-a-string' structures, with a bulbous head followed by a stem-like tail. Discussions have focused on whether their initial upwelling heads are hotter than the tails or cooler, as a result of entrainment of ambient mantle during ascent, and also on whether initial plume upwelling is a newtonian or non-newtonian process. The temperature of the mantle delivered to the base of the lithosphere is a critical parameter in such debates. Dry continental magmas can normally contribute little to this topic because their hottest (ultramafic) examples can be expected to be trapped, owing to their density, beneath the Moho. Here we report a rare case in which olivine (with 93.3% forsterite; Mg2SiO4) phenocrysts, precipitated from an unerupted komatiitic melt (approximately 24% MgO) of the Tristan mantle plume head 132 Myr ago, were carried to upper-crust levels in northwest Namibia by less Mg-rich (9.6-18.5% MgO) magmas. We infer that the hidden melt, generated when the plume impinged on the base of the lithosphere, originated in the mantle with a potential temperature of approximately 1,700 degrees C. This is approximately 400 degrees C above ambient and much hotter than the temperatures previously calculated for steady-state Phanerozoic mantle plumes. Published data show that the same conclusion can be reached for the initial Iceland and Galapagos plumes.

Journal Article↗