Effect of penicillin on ribonucleic acid synthesis in lymphocytes of sensitized individuals

Zusammenfassung Es wird gefunden, dass Penicillin zur RNS-Synthese während der ersten 4 h der Kultur stimuliert und 7–13% der Blutlymphozyten bei Menschen eine Sensibilisierung gegen dieses Antibioticum aufweisen. Der ermittelte Prozentsatz gleicht dem der unter Penicillineinfluss transformierenden Lymphozyten bei ein und derselben Person. Ein Einfluss von Penicillin auf die RNS-Synthese der Lymphozyten bei nicht sensibilisierten Personen wurde nicht gefunden.     

Ein Beitrag über die Art der Wirkung einiger Antituberkulotika

Summary The direct effect of any antituberculotics on pancreatic lipase was studied by the modified method ofWillstätter. The antituberculotics were found to activate the pancreatic lipase in the presence of Ca⁺⁺. Any cations, especially copper, decreases the lipase activity. Increasing antituberculotics concentration is accompanied by an increasing effect on the lipolytic action of lipase.     

Extrapyramidal pathways with monosynaptic effects upon primate α-motoneurons

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cis-cylohexane-1,2-diol in the beaver gland

Zusammenfassung Aus den Biberdrüsen wurdecis-Cyclohexan-1,2-diol isoliert und charakterisiert.

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The support of this work by the Colombo Plan administration of Canada is gratefully acknowledged.     

Synthesis and Characterization of Cross-linked Poly (β-Cyclodextin) Graft Poly(lactic acid) through Direct Polycondensation

1 Results Polylactide or polylactic acid (PLA) and poly(lactic-co-glycolic acid) (PLGA) have been utilized as bioabsorbable materials in the medical and pharmaceutical fields due to their biodegradable and biocompatible properties[1].However,due to its hydrophobicity and free carboxylic group,PLA or PLGA was not suitable for use to encapsulate the protein.Recently,poly (ε-caprolactone) and poly (D,L-lactide) were respectively grafted onto hydrophilic dextrin and gelatin to obtain the amphiphilic biodeg...     

Pathway selection by growth cones of identified motoneurones in live zebra fish embryos

How is the adult pattern of connections between motoneurones and the muscles that they innervate established during vertebrate development? Populations of motoneurones are thought to follow one of two patterns of development: (1) motor axons initially follow stereotyped pathways and project to appropriate regions of the developing muscle or (2) motor axons initially project to some regions that are incorrect, the inappropriate projections being eliminated subsequently. Here we observed individually identified motoneurones in live zebra fish embryos as they formed growth cones and as their growth cones navigated towards their targets. We report that from axogenesis, each motor axon followed a stereotyped pathway and projected only to the specific region of the muscle appropriate for its adult function. In addition, the peripheral arbor established by each motoneurone was restricted to a stereotyped region of its own segment and did not overlap with the peripheral arbor of the other motoneurones in that segment. We conclude that the highly stereotyped pattern of innervation seen in the adult is due to initial selection of the appropriate pathway, rather than elimination of incorrect projections.     

Tilman's predicted productivity-diversity relationship shown by desert rodents

Tilman has developed a model to predict the number of plant species that can coexist competitively on a limited resource base. Species diversity first increases over low resource supplies, then declines as the environment becomes richer. Although Tilman 's model was developed to describe interspecific interactions between plant species, it may also apply to animal species. Tilman questions whether animals specialize on particular proportions of nutrients. However, we believe animals probably specialize on relatively subtle microhabitat differences, especially in a multispecies competitive regime. Thus, microhabitats may act like nutrients. We hypothesize that animal species, too, show a peaked curve of diversity over productivity. The present data provide a confirmation of the hypothesis using rodent species. We have investigated the number of rodent species along a geographical gradient of increasing rainfall. The gradient extends from extremely poor desert habitats to those with annual rainfall over 300 mm. Because of the aridity , precipitation reflects productivity. The diversity pattern in desert rodents agrees with that predicted by Tilman for plants. It even possesses similar asymmetry, rising steeply then falling slowly. The pattern is duplicated in rocky and sandy habitats, each of which has a distinct and almost nonoverlapping assemblage of species. As mean precipitation is closely correlated with the variability of precipitation, the diversity pattern might also be caused by a decline in the frequency of disturbances, models for which have been proposed by several investigators.