University of Antananarivo

About: University of Antananarivo is a education organization based out in Antananarivo, Madagascar. It is known for research contribution in the topics: Population & Lemur. The organization has 1561 authors who have published 1703 publications receiving 30922 citations. The organization is also known as: Tananarive University & Antananarivo University.

Thiamine Deficiency in Tropical Pediatrics: New Insights into a Neglected but Vital Metabolic Challenge

Abstract: In humans, thiamine is a micronutrient prone to depletion that may result in severe clinical abnormalities. This narrative review summarizes current knowledge on thiamine deficiency (TD) and bridges the gap between pathophysiology and clinical presentation by integrating thiamine metabolism at subcellular level with its function to vital organs. The broad clinical spectrum of TD is outlined, with emphasis on conditions encountered in tropical pediatric practice. In particular, TD is associated with type B lactic acidosis and classic forms of beriberi in children, but it is often unrecognized. Other severe acute conditions are associated with hypermetabolism, inducing a functional TD. The crucial role of thiamine in infant cognitive development is also highlighted in this review, along with analysis of the potential impact of TD in refeeding syndrome during severe acute malnutrition (SAM). This review aims to increase clinical awareness of TD in tropical settings where access to diagnostic tests is poor, and advocates for an early therapeutic thiamine challenge in resource-limited settings. Moreover, it provides evidence for thiamine as treatment in critical conditions requiring metabolic resuscitation, and gives rationale to the consideration of increased thiamine supplementation in therapeutic foods for malnourished children.

Geology, petrology and isotope geochemistry of massif-type anorthosites from southwest Madagascar

Abstract: Four massif-type anorthosite bodies 25–100 km2 in area occur within high-pressure granulite facies supracrustal gneisses in southwestern Madagascar. Two of these bodies (Ankafotia and Saririaky) appear to have been pulled apart by 40 km in a ductile shear zone, but structural features such as sub-vertical stretching lineations indicate an origin by intense west-directed flattening and pure shear. Country rocks (Graphite Series) include abundant graphite schist (some with >60% graphite), marble, quartzite, and minor amphibolite and leucogneiss. Comagmatic granitoids (e.g. charnockites) are conspicuously absent. The anorthosite bodies are dominated by coarse grained anorthosites and leuconorites (feldspars typically 3–5 cm, up to 1 m); minor norites and oxide-rich ferrogabbros occur near the margins, but ultramafic rocks are absent. Typical mineralogy of the anorthositic rocks is: plagioclase (An41–54) + orthopyroxene (En38–66) ± augite (Mg♯ = 32–68) ± ilmenite ± magnetite ± apatite. High-alumina (to 6.1 wt% Al2O3) orthopyroxene megacrysts are widespread; most have exsolutions of calcic plagioclase (An72–85) but some contain garnet lamellae. Metamorphism has produced abundant recrystallization and sporadic coronitic garnet (Mg ♯=12–36) + clinopyroxene assemblages. Rb-Sr isotopic analyses of whole-rocks and minerals reveal no meaningful age relationships. The age of late Neoproterozoic metamorphism is best constrained at 559 ± 50 Ma by a 6-point Sm-Nd mineral isochron (whole rock, plag, pyx, ilm, apat, gar) from a Saririaky oxide-rich gabbro. The igneous crystallization age of the anorthosites is estimated at 660 ± 60 Ma by a 19-point combined whole-rock and mineral Sm-Nd isochron for samples from both the Ankafotia and Saririaky bodies. Initial isotopic ratios calculated at 0.66 Ga among 13 whole rocks are: Nd=+2.6 to +5.2 (mean=+3.7) and ISr=0.70328–0.70407 (mean=0.70347), indicating derivation of the Malagasy anorthosites from a depleted mantle source, and little, if any, contamination with Archean crustal material. One anorthosite sample with Nd=−1.4 and ISr=0.70344 (calculated at 0.66 Ga) probably reflects the effects of assimilation of Early to Middle Proterozoic crustal basement, but typical surrounding graphite schist (Nd=+0.3, ISr=0.70636, both at 0.66 Ga; TDM= 1131 Ma) represents only a minor potential contaminant for the anorthosite bodies. TDM model ages of the Malagasy anorthosites (797–1280 Ma; mean of 14 samples=949 Ma), as those of most other massif-type anorthosites, are older than the true crystallization age, because of crustal contamination effects. Our isotopic data, together with recent U-Pb data from the anorthosites and surrounding country rocks, are consistent with emplacement of the Malagasy anorthosite bodies at or before the start of a protracted, high-grade metamorphic event or series of events between about 630 and 550 Ma. This period coincides with the collision between, and amalgamation of, East and West Gondwana.

Phylogeny of Halictidae with an emphasis on endemic African Halictinae

Abstract: We review the literature on phylogeny, fossil record, biogeography, and social evolution in Halictidae. We then present a phylogenetic analysis of tribal, generic, and subgeneric relationships within the subfamily Halictinae using a combined data set of three nuclear genes: long-wavelength (LW) opsin, wingless, and EF-1α. The data set includes 89 species in 34 genera representing all four halictid subfamilies, and all tribes of the subfamily Halictinae. Our study provides several new insights into the phylogeny of the African Halictinae. First, our results support a close relationship between Mexalictus (a small genus of bees occurring at high elevations in the mountains of western North and Central America) and the African/Asian genus Patellapis. Second, our results support placement of the parasitic genus Parathrincostoma well within its host genus Thrinchostoma, suggesting that Parathrincostoma should be treated as a subgenus of Thrinchostoma. Finally, our data set provides strong support for the monophyly of Patellapis (sensu Michener, 2000) and establishes monophyletic groups within the African subgenera that could be the basis for future taxonomic studies.

Mitochondrial DNA origin of indigenous malagasy chicken.

Abstract: We report the mitochondrial DNA (mtDNA) characterization of 77 indigenous chickens (fighting and meat birds) from Madagascar, using DNA sequences of the first hypervariable segment of the D-loop. Comparison with reference samples from the African continent and Asia revealed two mtDNA haplogroups, suggesting a dual geographic and genetic origin for the indigenous Malagasy chickens. The most common haplogroup was present in 65 individuals of the two types; it is likely of Indonesian origin. The second haplogroup was observed in 12 fighting birds and meat chickens; it could be of African continental origin and/or the result of recent introgression with commercial lines. We further studied a G/A single nucleotide polymorphism at nucleotide position 1892 bp of the coding sequence of the Mx gene that is reported to be one of the candidate susceptible/resistant genes to viral infection in chicken. Our results indicate the "susceptible" allele G is the most common with frequencies of 65% and 70% in Malagasy fighting and meat chickens, respectively. However, the allelic frequency difference between the two types of chickens is not significant (P > 0.05). These results are discussed in light of our current linguistic and archaeological knowledge on the origin of indigenous Malagasy chickens.