Arabic scripts employed in West African manuscripts have not been fully explored in scholarly literature. The aim of this paper is twofold: to discuss the literature available on this issue and to advance a classification of West African writing styles. This classification is based on the case study of the “de Gironcourt” collection of Arabic manuscripts, gathered in the modern states of Mali, Niger, and Nigeria at the beginning of the twentieth century.
Oral administration of L-tryptophan to rats produced two main biochemical and pharmacological effects: a marked increase in urinary 5-hydroxyindoleacetic acid excretion, and a significant reduction in the urine flow after a water load. Urinary 5-hydroxyindoleacetic acid excretion reached its maximum 2 to 6 hr after the administration of tryptophan, and it increased with the dose of the amino acid. Antidiuresis was seen after the administration of L-tryptophan, 200 mg/kg, or more. The effect appeared promptly and it was roughly proportional to the dose of the amino acid administered. Both antidiuretic effect and increase in urinary 5-hydroxyindoleacetic acid excretion were more intense after oral than after parenteral administration of L-tryptophan. D-Tryptophan, in oral doses up to 1,000 mg/kg, produced neither an increase in urinary 5-hydroxyindoleacetic acid nor a reduction of diuresis. Available evidence suggests that reduction of urine flow is a consequence of biosynthesis and release of 5-hydroxytryptamine by the gastrointestinal mucosa. Tryptamine produced by direct decarboxylation of L-tryptophan does not seem to play any important role.In the course of experiments on precursors of 5-hydroxytryptamine, it was observed that oral administration of L-tryptophan, the initial precursor of the amine, produced two main effects: a conspicuous increase in the urinary excretion of 5-hydroxyindoleacetic acid, and a significant reduction in the urine flow following a water load. The last effect seemed particularly worth studying, as it was caused in the normal animal by a common dietary amino acid.The present experiments were undertaken to investigate which compound was responsible for the observed antidiuresis, in order to provide additional information on the physiological role of 5-hydroxytryptamine in the control of diuresis, as well as on the biosynthesis and turnover rate of the amine in the enterochromaffin cell system, which is generally considered the main site of production of 5-hydroxytryptamine.
METHODSExperimental animals. Adult albino rats of both sexes weighing 170 to 230 g, all of the same breed, were used. They were kept on a standard laboratory diet. During the afternoon preceding each experiment they -received a diet rich in water (soaked bread and vegetables); in the night the animals were deprived of food but allowed free access to water. On the next morning the animals were given tryptophan either orally (amino acid dissolved in 5 ml. tepid tap water/100 g of rat) or parenterally (amino acid dissolved in 3 ml. 0.9% sodium chloride solution/100 g of rat). Doses of the administered L-tryptophan varied from 50 to 1,000 mg/kg; those of D-tryptophan from 200 to 1,000 mg/kg. In some experiments the S
Recent research points to a renewed scholarly interest in the West African Middle Ages and the Sahelian imperial tradition. However, in these works only tangential attention is paid to the role of Muslims, and especially to clerical communities. This essay tackles theoretical and historiographical insights on the role of African Muslims in the era of the medieval empires and argues that the study of Islam in this region during the Middle Ages still suffers from undertheorizing. On the contrary, by using a ‘discursive approach’ scholars can unravel access to fascinating aspects of the history of West African Muslims and in particular to the crucial role played by clerical communities, who represented one node of the web of diffused authority which is characteristic of precolonial West African social and political structures.
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