Synthesis and biological activities of peptidomimetic analogues of compound A71623, a potent and selective CCK-A receptor agonist

Summary The involvement of cholecystokinin receptors in the phenomenon of satiety has been the impetus for significant research efforts, leading to the design and synthesis of CCK-A selective agonists for the possible treatment of obesity. The Abbott laboratories have described a novel series of pseudotetrapeptides represented by compound A71623, a highly potent and selective peripheral receptor agonist, but possessing very poor bioavailability. Starting from the structural requirements of this series of compounds, a peptidomimetic study was investigated, especially focusing on the N-terminal part of A71623. Using standard coupling methods, introduction of unnatural aromatic amino acids bearing a 2-carboxyethyl side chain on their α-amino group, along with backbone length modulation, afforded selective analogues, presenting a highly modified peptidic backbone. From our two lead compounds, further optimization is under development, tending towards nonpeptidic structures.     

Sodium-1,2-C Acetate Incorporation in Roots of Frost-hardy and Less Hardy Alfalfa Varieties under Hardening Conditions

When the temperature of incorporation of sodium acetate-1, 2-¹⁴C into lipids of alfalfa (Medicago media Pers. var. Rambler and Medicago sativa L. var. Caliverde) roots was lowered from 22 C to 1 C, elongation and desaturation of fatty acids and the labeling of phosphatidylcholine were strongly stimulated.     

Existence of cytoplasmic inclusions in acinic cells of the exocrine pancreas of the hyperglycemic obese mouse]

Peculiar cytoplasmic inclusions with crystalline pattern are described in the obese hyperglycaemic mouse pancreas acinar cells. They are generally associated with filamentous structures. However, crystalline and filamentous inclusions have also been observed in isolated forms. These inclusions are not digested by pronase. Since they have also been encountered in normal mice, it seems that the hyperglycaemic syndrome does not play a role in inducing their formation.     

Microfilamentous system and secretion of enzyme in the exocrine pancreas. Effect of cytochalasin B

The microfilaments in the acinar cell of the exocrine pancreas are essentially located in the apical part of the cell: thin microfilaments (50 A), cytochalasin B (CB)-sensitive, form the axis of the microvilli and a network lying beneath the apical membrane; thicker filaments (100 A), at least partly CB-insensitive, form bundles parallel to the plasma cell membrane and the desmosomal links. CB interaction with the acinar cell of the exocrine pancreas involves at least two sites: a membrane site involved in the inhibitory effect of CB on the monosaccharide transport and a less sensitive site at the filamentous level at least partly responsible for the inhibitory effect of CB in the secretion of the exportable enzyme from the pancreatic cell. CB did not alter the energy balance of the acinar cell nor the exchanges of 15-Ca between the extracellular medium and the pancreatic tissue. CB (2 times 10-minus 7 and 2 times 10-minus 6 M) has secretagogue properties whereas CB (2 times 10-minus 5 M) has inhibitory effect on stimulated secretion and secretagogue properties. The mechanism of these secretory effects is not yet explained. The analysis presented in this investigation affords strong evidence for the involvement of the microfilamentous network in the last steps of the secretory cycle in the acinar cell of the exocrine pancreas.     

Studies of mixed anaerobic infections involving Bacteroides gingivalis

The infectiousness of several combinations of bacteria containing Bacteroides gingivalis and other bacteria associated with periodontal diseases was evaluated by subcutaneous injection to guinea pigs. Among the seven mixtures studied, only one permitted the development of an infection easily transmissible to a second guinea pig; this bacterial mixture was composed of B. gingivalis, Fusobacterium nucleatum, Eubacterium saburreum, and Capnocytophaga ochracea (formerly Bacteroides ochraceus). Owing to its ability to synthesize many lytic enzymes and potentially cytotoxic products, B. gingivalis represented the most virulent species of the mixture. Results from in vitro studies suggest that the development of B. gingivalis in the infected animal depends on the growth of C. ochracea. Succinic acid produced in large amount by C. ochracea seems to be one of the growth factors used by B. gingivalis.     

INFLUENCE DU SUPERPARASITISME SUR LA DURÉE DU DÉVELOPPEMENT LARVAIRE ET LE POIDS DU PARASITOÏDE LIXOPHAGA DIATRAEAEÉLEVÉ DANS UN HÔTE DE SUBSTITUTION GALLERIA MELLONELLA

Résumé G. mellonella infestée au dernier stade larvaire avec 1, 2, 3 ou 5 planidia/hôte (ph/H) produit 1 à 5 pupes/hôte (pu/H). La mortalité des chenilles augmente avec le nombre de pl/H. Le poids des pupes et décroît avec un nombre croissant de pu/H (18,2 à 12,9 mg pour les et 12,5 à 9,7 mg pour les ). Le développement larvaire dure 8,7 j. chez les et 8,3 chez les ; il est peu affecté par le superparasitisme. Avec 1, 2, 3 et 5 pl/H nous obtenons 0,84–1,61–2,17 et 3,43 pu/H et 0,81–1,48–2,10 et 3,11 imagos/H. L'optimum est de 3 pl/H ou 1 à 2=pl/H pour obtenir des parasitoïdes plus lourds.

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Summary The influence of superparasitism on larval and pupal development is investigated. Last-larval instar G. mellonella (200±5 mg) were infected with 1, 2, 3 or 5 planidia/host (pl/H) producing 1 to 5 pupae per host (pu/H). Host mortality (8.6–8.3–14.3 and 22.2%) increased with the number of planidia. The planidia may transmit a bacteriosis. Pupal weight ( and ) decreased as number of pu/H increased. pupae were heavier than ones: 12.9 to 18.2 mg for against 9.7 to 12.5 mg for . Larval development lasted slightly longer for (8.7 d.) than for (8.3 d.), and its duration was little affected by superparasitism. 1, 2, 3 or 5 pl/H yielded 0.84–1.61–2.17 and 3.43 pu/H and 0.81–1.48–2.10 and 3.11 adults/H. An optimum was obtained with 3 planidia of L. diatraeae on G. mellonella or 1 to 2 to obtain heavier parasitoids.

     

Antifungals: Mold control and safe levels in artificial media forTrichogramma [Hymenoptera: Trichogrammatidae]

Ten chemicals known to be fungicides are tested in artificial media forTrichogramma dendrolimi Matsu. [Hymenoptera: Trichogrammatidae]. Tests are performed in France by using artificial host egg capsules. Most of the fungicides cannot control fungus or are toxic forTrichogramma at effective levels. Geneticin, Amphotericin B and Nystatin, used at proper levels are able to control molds efficiently without modifyingTrichogramma development. These antifungals are also tested in actual conditions of mass production, in Guangzhou (China).      

Enquête sur la répartition des tachninaires [Diptera: Tachnidae] prasitoïdes de la pyrale du maïsOstrinia nubilalis [Lepidoptera: Pyralidae] en France (1985–87)

Résumé Trois annés d'éhantillonnage automnal de pyrale du ma?s dans différentes régions ma?sicoles de France ont permis de déterminer le taux de parasitisme par les Tachinidae. Ce taux varie de 1% à 51% selon les régions et les années. Les tachinaires sont préents dans toutes les zones étudiées.Lydella thompsoni Hert. est l'espèce la plus abondante et la plus répandue.Pseudoperichaeta nigrolineata Walk. se rencontre dans le Sud-Ouest. Les Tachinidae pourraient jouer un r?le important dans la régulation des populations de pyrale.