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Algae -- a poor man's HAART?

Drawing inferences from epidemiologic studies of HIV/AIDS and in vivo and in vitro HIV inhibition by algae, we propose algal consumption as one unifying characteristic of countries with anomalously low rates. HIV/AIDS incidence and prevalence in Eastern Asia ( approximately 1/10000 adults in Japan and Korea), compared to Africa ( approximately 1/10 adults), strongly suggest that differences in IV drug use and sexual behavior are insufficient to explain the 1000-fold variation. Even in Africa, AIDS/HIV rates vary. Chad has consistently reported low rates of HIV/AIDS (2-4/100). Possibly not coincidentally, most people in Japan and Korea eat seaweed daily and the Kanemba, one of the major tribal groups in Chad, eat a blue green alga (Spirulina) daily. Average daily algae consumption in Asia and Africa ranges between 1 and 2 tablespoons (3-13 g). Regular consumption of dietary algae might help prevent HIV infection and suppress viral load among those infected.

Acquired Immunodeficiency Syndrome↗

Evaluation of the discriminatory power of variable number tandem repeat (VNTR) typing of Mycobacterium bovis strains.

The discriminatory power of variable number tandem repeat (VNTR) typing based on 16 known loci (12 MIRUs, 3 ETRs and VNTR 3232) was assessed for Mycobacterium bovis strains collected sequentially at the slaughterhouse of N'Djaména, Chad. Of 67 M. bovis strains analyzed, 67% were clustered. In this study, VNTR typing was highly discriminative with an overall allelic diversity (h(oa)) of 0.922. We defined five loci (ETR A, B, C and MIRU 26, 27) as highly (h>0.25), two loci (MIRU 4, and VNTR 3232) as moderately (0.11<h<0.25) and three loci (MIRU 16, 20, 31) as poorly (0.01<h<0.11) discriminative. Six loci (MIRU 2, 10, 23, 24, 39, and 40) showed no polymorphism at all. VNTR typing of the five highly discriminative loci (h=0.917) proved to be most appropriate for first line typing of M. bovis strains of Chad and superior than spoligotyping (h(sp)=0.789). In contrast to Mycobacterium tuberculosis strains, a consensus on VNTR loci needs to be found for M. bovis strains. The selection of a generally agreed set of VNTR loci for molecular discrimination of M. bovis in different geographical settings is discussed.

Alleles↗

Anthracothere dental anatomy reveals a late Miocene Chado-Libyan bioprovince.

Recent discovery of an abundant and diverse late Miocene fauna at Toros-Ménalla (Chad, central Africa) by the Mission Paléoanthropologique Franco-Tchadienne provides a unique opportunity to examine African faunal and hominid evolution relative to the early phases of the Saharan arid belt. This study presents evidence from an African Miocene anthracotheriid Libycosaurus, particularly well documented at Toros-Ménalla. Its remains reveal a large semiaquatic mammal that evolved an autapomorphic upper fifth premolar (extremely rare in Cenozoic mammals). The extra tooth appeared approximately 12 million years ago, probably in a small northern African population isolated by climate-driven fragmentation and alteration of the environments inhabited by these anthracotheriids [Flower, B. P. & Kennett, J. P. (1994) Palaeogeogr. Palaeoclimatol. Palaeoecol. 108, 537-555 and Zachos, J., Pagani, M., Sloan, L., Thomas, E. & Billups, K. (2001) Science 292, 686-693]. The semiaquatic niche of Libycosaurus, combined with the distribution and relationships of its late Miocene species, indicates that by the end of the Miocene, wet environments connected the Lake Chad Basin to the Libyan Sirt Basin, across what is now the Sahara desert.

Animals↗

Imported Brucellosis associated with Plasmodium falciparum malaria in a traveler returning from the tropics.

We report a microbiologically confirmed case of Brucella melitensis and Plasmodium falciparum malaria coinfection in a febrile traveler returning from Chad, Africa. The patient had been doing veterinary research in rural Chad; during that time she took no antimalarial chemoprophylaxis. Our report highlights the importance of blood cultures as well as malaria smears in febrile travelers returning from the tropics.

Adult↗

Health and equity impacts of a large oil project in Africa.

A system of external reviewers was established by the World Bank Group to promote a thorough environmental and health impact assessment for the 3.5 billion US dollars Chad Oil Export Project, based on a loan request from Chad, Cameroon and a consortium of oil companies. The environmental and health assessment process showed evidence of its ability to minimize the number of deaths from malaria, traffic accidents and construction accidents and the occurrence of minor sexually transmitted diseases, diarrhoeal diseases and respiratory diseases; it also probably limited adverse impacts on wildlife and tropical ecology along the pipeline route. However, the system was unable to deal with the larger issues, which included: the intrinsic unsustainability of this kind of extraction project; its eventual contribution to large amounts of greenhouse gases in the atmosphere; the lack of equity in sharing the risks, negative impacts, benefits and decision-making among the various participants in the project; and the possible acceleration of transmission of the AIDS virus into central Africa. Unfortunately, the international panel of experts appointed by the World Bank Group was largely ignored by the project proponents, and had little success in minimizing the most serious impacts or in improving the social equity of the project.

Cameroon↗

A survey of Simulium control in Africa.

It has become possible to control or even eradicate the Simulium fly vectors of Onchocerca volvulus, the causative organism of onchocerciasis. There are two vectors in Africa-namely, S. damnosum, characteristic of the rivers of West Africa, and S. neavei, which breeds on the carapaces of crabs in the streams of East Africa. The use of DDT applied to the water at a concentration as low as 0.1 p.p.m. for 30 minutes eliminates the larvae of Simulium. Such larvicidal methods have eradicated S. neavei from western Kenya and virtually eradicated S. damnosum from the Victoria Nile in Uganda. Excellent control sufficient to render the transmission of onchocerciasis almost negligible has been obtained at Léopoldville (Republic of the Congo) and in circumscribed areas in southern Chad, Northern Nigeria, and Sierra Leone. The following survey describes operational research on Simulium control carried out in Kenya, Uganda, the Congo, Chad, Nigeria, Ghana, Upper Volta and Sierra Leone.

Africa↗

Seroepidemiological survey of HTLV-I infection among randomized populations of western central African countries.

Between 1987 and 1988, a survey to determine the distribution of HTLV-I infection was conducted in a representative population of adults, living in southern Chad, Cameroon, and Equatorial Guinea. Populations studied were selected by the cluster sampling technique. Sera were tested for IgG antibodies to HTLV-I by ELISA. ELISA-positive sera were retested by Western blot. The study comprised 2,301 adults, all apparently healthy. Crude prevalence rates range from 0.5 to 11.8%. We found three clearly different areas of HTLV-I seroprevalence rates. An area of low seropositivity in southern Chad and northern Cameroon (0.5-2.0%), an area of moderate seropositivity in the savannah region of Ngaoundere, Cameroon (4.2%) and in Bata, Equatorial Guinea (6.5%), and lastly an area of high seropositivity (8.6-11.8%) in the equatorial forest area of Equatorial Guinea and southern Cameroon. HTLV-I seroprevalence rates increased with age up to 12.6% after 40 years old in the areas of high seropositivity. There was no difference between male and female age-adjusted prevalence rates in all of the areas studied.

Adolescent↗

Spine anatomy reveals the diversity of catfish through time: a case study of Synodontis (Siluriformes).

Synodontis (Mochokidae, Siluriformes) is a freshwater catfish endemic to Africa. The 118 extant species are present in almost all hydrographic basins. Some species are restricted to a single stream, whereas others have a vast distribution. Synodontis is known in the fossil record since the Miocene, and its history depends on the connections among African basins through time. The identification of species in the fossil record is essential to reconstruct this historical pattern. Catfish pectoral and dorsal spines are robust, they preserve well and they form most of the fossil remains for the genus Synodontis. Unfortunately, the criteria for the identification of extant Synodontis species are not applicable to fossil specimens. Here, we define 11 original morphological characters that permit to discriminate four extant species from the Chad-Chari hydrographic system. Six of these characters are defined on pectoral spines and five on dorsal spines. We then show that these characters can be used successfully for identifying fossil specimens. In particular, we present a case study in which we identify Synodontis cf. schall and Brachysynodontis cf. batensoda in the hominid-bearing sector Toros-Menalla (Late Miocene, northern Chad). We show that spine anatomy can be a powerful tool to recognise catfish species through time and thus to identify historical diversity pattern.

Africa↗

Geochemical variations in aeolian mineral particles from the Sahara-Sahel Dust Corridor.

The Sahara-Sahel Dust Corridor runs from Chad to Mauritania and expels huge amounts of mineral aerosols into the Atlantic Ocean. Data on samples collected from Algeria, Chad, Niger, and Western Sahara illustrate how corridor dust mineralogy and chemistry relate to geological source and weathering/transport history. Dusts sourced directly from igneous and metamorphic massifs are geochemically immature, retaining soluble cations (e.g., K, Na, Rb, Sr) and accessory minerals containing HFSE (e.g., Zr, Hf, U, Th) and REE. In contrast, silicate dust chemistry in desert basins (e.g., Bodélé Depression) is influenced by a longer history of transport, physical winnowing (e.g., loss of Zr, Hf, Th), chemical leaching (e.g., loss of Na, K, Rb), and mixing with intrabasinal materials such as diatoms and evaporitic salts. Mineral aerosols blown along the corridor by the winter Harmattan winds mix these basinal and basement materials. Dusts blown into the corridor from sub-Saharan Africa during the summer monsoon source from deeply chemically weathered terrains and are therefore likely to be more kaolinitic and stripped of mobile elements (e.g., Na, K, Mg, Ca, LILE), but retain immobile and resistant elements (e.g., Zr, Hf, REE). Finally, dusts blown southwestwards into the corridor from along the Atlantic Coastal Basin will be enriched in carbonate from Mesozoic-Cenozoic marine limestones, depleted in Th, Nb, and Ta, and locally contaminated by uranium-bearing phosphate deposits.

Aerosols↗

Combined modality treatment for stage III ovarian carcinoma.

Thirty-eight Stage III ovarian carcinoma patients were treated with a combined modality protocol consisting of sequential initial surgery with a maximal tumor reduction, CHAD combination chemotherapy, second look reductive surgery and whole abdominal irradiation. Sixteen patients (42%) had minimal residual tumors (less than 2 cm) after initial surgery (Stage IIIA) and 22 (58%) had large residual tumors (greater than 2 cm) (Stage IIIB). The patients received 3-14 courses of CHAD combination chemotherapy, with a response rate (CR + PR) in the evaluable (Stage IIIB) patients of 91%. Twenty-eight patients had a second attempt of cytoreductive operation (10 Stage IIIA patients and 18 Stage IIIB patients). In 10 patients no residual tumor was found. In another 12 patients residual tumor (less than 2 cm) was found and completely resected, whereas in six patients a complete resection of large residual tumors (greater than 2 cm) was not possible. Twenty-one of the patients also completed a course of whole abdominal radiotherapy. Radiation was well-tolerated with the usual expected amounts of nausea, vomiting, diarrhea and transient leukopenia and thrombocytopenia. 11/21 (52%) of the patients relapsed within the first 18 months after completion of radiotherapy. The actuarial relapse-free survival at 36 months from completions of radiotherapy was 44%. The actuarial survival for the whole group from diagnosis was 43% at 3 years (70% for Stage IIIA and 41% for Stage IIIB). The data indicated that this combined modality protocol is both feasible and well-tolerated but its curative potential for patients with advanced ovarian carcinoma is as yet unknown.

Adenocarcinoma↗

Developing meaningful cohorts for human exposure models.

This paper summarizes numerous statistical analyses focused on the US Environmental Protection Agency's Consolidated Human Activity Database (CHAD), used by many exposure modelers as the basis for data on what people do and where they spend their time. In doing so, modelers tend to divide the total population being analyzed into "cohorts", to reduce extraneous interindividual variability by focusing on people with common characteristics. Age and gender are typically used as the primary cohort-defining attributes, but more complex exposure models also use weather, day-of-the-week, and employment attributes for this purpose. We analyzed all of these attributes and others to determine if statistically significant differences exist among them to warrant their being used to define distinct cohort groups. We focused our attention mostly on the relationship between cohort attributes and the time spent outdoors, indoors, and in motor vehicles. Our results indicate that besides age and gender, other important attributes for defining cohorts are the physical activity level of individuals, weather factors such as daily maximum temperature in combination with months of the year, and combined weekday/weekend with employment status. Less important are precipitation and ethnic data. While statistically significant, the collective set of attributes does not explain a large amount of variance in outdoor, indoor, or in-vehicle locational decisions. Based on other research, parameters such as lifestyle and life stages that are absent from CHAD might have reduced the amount of unexplained variance. At this time, we recommend that exposure modelers use age and gender as "first-order" attributes to define cohorts followed by physical activity level, daily maximum temperature or other suitable weather parameters, and day type possibly beyond a simple weekday/weekend classification.

Adolescent↗

Infertility in central Africa.

OBJECTIVES: To determine the prevalence and risk factors of primary and secondary infertility in the four Central African countries of Cameroon, Chad, Central African Republic and Gabon. METHODS: Primary infertility was approximated by the percentage of women childless after at least 5 years of marriage. The percentage with no birth at least 5 years subsequent to a previous birth was considered to have secondary infertility. Logistic regression and discrete logistic regression models were estimated to determine the risk factors of primary and secondary infertility, respectively. The relatively few women who were defined as infertile and reported using a traditional or modern method of contraception at survey date were considered fertile to reduce bias from falsely classifying effective contraceptive users as infertile. RESULTS: The prevalence of infertility was highest in Central African Republic and lowest in Chad: primary infertility ranged from 6.9% to 3.1% and secondary infertility for women aged 20-44 years ranged from 26.5% to 18.9%. Women married more than once vs. only once and formerly married women vs. women living with their husbands had higher odds of primary and secondary infertility. Also, younger cohorts had relatively higher risks of primary (born after 1970) and secondary infertility (born after 1960) compared with women born before 1960. In contrast, place of residence, religion, education of wife or husband and socio-economic status were generally not associated with primary or secondary infertility. CONCLUSIONS: Infertility is still prevalent in Central Africa and new interventions aimed at reducing the incidence and social implications of pathologic infertility are needed.

Adolescent↗

Differential adherence of osteoarthritis and rheumatoid arthritis synovial fibroblasts to cartilage and bone matrix proteins and its implication for osteoarthritis pathogenesis.

In osteoarthritis (OA), cartilage and bone fragments have been described within the synovial tissue which are surrounded by synovial cells (i.e. detritus synovitis). These cells appear to attach actively to the cartilage and bone fragments. In rheumatoid arthritis (RA), on the other hand, synovial fibroblasts (SF) have also been shown to be localized at sites of invasion into cartilage and bone and to degrade extracellular matrix (ECM) by secreting proteolytic enzymes. One prerequisite for exerting their aggressive properties is the attachment to cartilage and bone ECM. This attachment appears to be mediated by the expression of different adhesion molecules for which corresponding binding sites on ECM components are known. As it has not been addressed to which ECM proteins SF adhere and with which affinity this process takes place, we investigated the adherence of SF from patients with OA and RA to different cartilage and bone matrix proteins. Synovial tissue samples were obtained during synovectomy or arthroplastic surgery and used for isolating and culturing SF. Synovial cells attaching to cartilage/bone fragments were characterized using immunohistochemistry. The adherence of SF to ECM proteins was examined using an adhesion assay with the following proteins coated on 96-well plates: aggrecan (AGG), bone sialoprotein (BSP), cartilage oligomeric matrix protein (COMP), collagen type I, II and VI, proline arginine-rich, end leucine-rich repeat protein (PRELP), osteopontin (OPN) and recombinant chondroadherin (CHAD). Bovine serum albumin was used as negative control. In addition, adhering fibroblasts were photographed using a phase-contrast microscope. As compared with RA-SF, significantly higher numbers of OA-SF adhering to collagen type II, OPN and CHAD could be detected (P < 0.05). In contrast, RA-SF showed increased attachment to collagen type II, OPN and BSP. Adhesion to AGG, COMP and PRELP appeared not to be significantly increased and differed widely among the SF samples, and, apart from one exception (BSP), OA-SF adhered in higher numbers to the matrix proteins than did RA-SF. Using immunohistochemistry, synovial cells attached to cartilage/bone fragments could be shown to predominantly express CD68 (>/=50%). The CD68-negative population was of the fibroblast phenotype (AS02 positive). The study demonstrates that the binding pattern of OA-SF and RA-SF to ECM proteins differs considerably and therefore provides novel insights into the difficult pathophysiology of OA and RA. In general, it appeared that SF adhere primarily to ECM proteins that contain known binding sites for adhesion molecules (e.g. integrins: collagen/integrin alpha(2)beta(1)) and that higher numbers of OA-SF adhered to the cartilage and bone matrix proteins than did RA-SF.

Arthritis, Rheumatoid↗

Polymorphism and polytypy for pericentric inversions in 38-chromosome Mastomys (Rodentia, Murinae) and possible taxonomic implications.

Chromosome banding analysis (R- and C-bands) of two 38-chromosome Mastomys specimens originating from the Ivory Coast and Uganda revealed different numbers of autosome arms (NFa), equal to 51 and 60, respectively. Comparison of their chromosome banding patterns with those of Mastomys specimens from the Sudan (NFa = 41) and Senegal (NFa = 51-54), studied previously, showed that variation of the NFa from 40 to 60 throughout the species distribution is the result of a pericentric inversion polymorphism involving 3-12 chromosome pairs. At the population level, this variation is much narrower and never results from more than two chromosome pairs involved in inversion polymorphism. Taking into account that the NFa values recorded to date form a well-defined discontinuous row, we presume that introgressive hybridization between populations differing from each other by 3-5 to 11-12 pericentric inversions is interrupted. From there, the hypothesis of the existence of at least three cryptic species (designated provisionally as MER-1, MER-2, and MER-3) within 38-chromosome Mastomys populations previously assigned to M. erythroleucus can be made. It looks likely that one of them, possessing a karyotype with an NFa = 50-56, is widely distributed throughout sub-Saharan Africa and includes karyotyped populations from Senegal, the Ivory Coast, Mali, Benin, Cameroon, Zaire, and the Sudan. The second species (MER-2) includes the specimens karyotyped (NFa = 40-41) from Chad and the Sudan. Finally, a third tentative species (MER-3) corresponds to specimens with NFa = 59-60 found in East Zaire and Uganda, as well as possibly Mali and Chad.

Animals↗

The catalytic domains of thiamine triphosphatase and CyaB-like adenylyl cyclase define a novel superfamily of domains that bind organic phosphates.

BACKGROUND: The CyaB protein from Aeromonas hydrophila has been shown to possess adenylyl cyclase activity. While orthologs of this enzyme have been found in some bacteria and archaea, it shows no detectable relationship to the classical nucleotide cyclases. Furthermore, the actual biological functions of these proteins are not clearly understood because they are also present in organisms in which there is no evidence for cyclic nucleotide signaling. RESULTS: We show that the CyaB like adenylyl cyclase and the mammalian thiamine triphosphatases define a novel superfamily of catalytic domains called the CYTH domain that is present in all three superkingdoms of life. Using multiple alignments and secondary structure predictions, we define the catalytic core of these enzymes to contain a novel alpha+beta scaffold with 6 conserved acidic residues and 4 basic residues. Using contextual information obtained from the analysis of gene neighborhoods and domain fusions, we predict that members of this superfamily may play a central role in the interface between nucleotide and polyphosphate metabolism. Additionally, based on contextual information, we identify a novel domain (called CHAD) that is predicted to functionally interact with the CYTH domain-containing enzymes in bacteria and archaea. The CHAD is predicted to be an alpha helical domain, and contains conserved histidines that may be critical for its function. CONCLUSIONS: The phyletic distribution of the CYTH domain suggests that it is an ancient enzymatic domain that was present in the Last Universal Common Ancestor and was involved in nucleotide or organic phosphate metabolism. Based on the conservation of catalytic residues, we predict that CYTH domains are likely to chelate two divalent cations, and exhibit a reaction mechanism that is dependent on two metal ions, analogous to nucleotide cyclases, polymerases and certain phosphoesterases. Our analysis also suggests that the experimentally characterized members of this superfamily, namely adenylyl cyclase and thiamine triphosphatase, are secondary derivatives of proteins that performed an ancient role in polyphosphate and nucleotide metabolism.

Journal Article↗

Chemotherapeutic and surgical induction of pathological complete remission and whole abdominal irradiation for consolidation does not enhance the cure of stage III ovarian carcinoma.

Thirty-eight patients with stage III ovarian carcinoma were treated with a protocol consisting of an initial phase of induction of remission with cyclophosphamide, hexamethylmelamine, doxorubicin, and cisplatin (CHAD) combination chemotherapy and a second laparotomy for resection of residual tumors, followed by a consolidation phase with curative doses of whole abdominal radiation. Six patients (16%) had stage IIIA disease, ten (26%) IIIB, and 22 (58%) had stage IIIC disease. All patients received three to 14 courses of CHAD chemotherapy with a clinical response rate (complete [CR] and partial [PR]) of 91%. Thirty-three patients underwent the second operation. In 14 patients no residual tumor was found, and in another 11 residual tumors found were totally resected. Thus, 25 of 33 (76%) were classified as in pathological complete remission (PCR) after this operation. Whole abdominal irradiation was well tolerated, although 12 of 29 (42%) of the irradiated patients required more than a 2-week interruption of the treatment course because of leukopenia and/or thrombocytopenia. The actuarial 5-year survival and disease-free survival rates for the whole group were 27% and 17%, respectively, and for the 29 patients who received the complete sequence of the prescribed protocol treatments, 35% and 20%, respectively. A univariate analysis of clinical parameters showed that inherent biological features, such as histology and grade, were the most dominant factors affecting prognosis, and that neither the aggressive surgical approach employed, nor the high-dose whole abdominal irradiation, significantly affected the outcome. The long-term results suggest that although our combined modality protocol was well tolerated, it failed to enhance the cure of stage III ovarian carcinoma. The possible biological and therapeutic vectors affecting this outcome are discussed.

Abdomen↗

Enhancement of the cardiac beta-adrenergic system at an early diabetic state in spontaneously diabetic Chinese hamsters.

Serial changes in cardiac norepinephrine content and the beta-adrenergic system were investigated during the development of cardiomyopathy in spontaneously diabetic Chinese hamsters (CHAD strain), in comparison to age-matched control Chinese hamsters (CHA) or non-diabetic CHAD hamster littermates. Cardiac norepinephrine content and beta-adrenergic receptor density significantly increased in short-term diabetics. These changes preceded both the development of cardiac hypertrophy and the enhanced response of adenylyl cyclase to isoproterenol plus 5'-guanylylimidodiphosphate [Gpp (NH)p], sodium fluoride, or forskolin stimulation. However, as the diabetic state developed cardiac norepinephrine content, beta-adrenergic receptor density, and adenylyl cyclase activity returned to control levels. The amount of stimulatory or inhibitory guanine nucleotide binding proteins in the diabetic group was similar to those in the control groups. These data suggest that the cardiac beta-adrenergic system is enhanced by the alterations in cardiac sympathetic activity during early diabetes, which are associated with the duration of diabetes rather than with the degree of hypertrophy or strain differences.

Animals↗

A comparison of the expression pattern of five genes of the family of small leucine-rich proteoglycans during mouse development.

For five members of the family of the small leucine-rich proteoglycans (SLRPs), the expression pattern during fetal development was analyzed. RNA in situ hybridization on whole body sections of mouse embryos was performed for biglycan (Bgn), decorin (Dcn), fibromodulin (Fmod), chondroadherin (Chad), and lumican (Lum). Special attention was given to the question of whether these patterns coincide only with sites of collagen secretion in connective tissue during tissue modeling or if expression can be observed at specific sites of organ differentiation also. In general, Fmod, Lum, and Bgn are expressed at sites of cartilage and bone formation and interstitial tissue deposition; Chad is expressed only at sites of cartilage; and Dcn is expressed only at sites of interstitial tissue deposition. However, there are some distinct developmental stages where no collagen secretion is known to occur. For example, this applies for the expression of Fmod in the forming somites of stage 9.5 postconception (p.c.), for Dcn and Lum in later stage embryos in the pituitary gland and dorsal root ganglia, and for Bgn and Dcn during differentiation in the kidney. These studies provide further evidence for a role of these molecules during connective tissue organization but also for an involvement at specific sites of organ differentiation.

Animals↗