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.     

Evaluation of the ability of intact platelets to accumulate acridine organge

Summary A new approach to the evaluation of the uptake of fluorescent, probes by intact, cells is described. Acridine organe (AO) was used because it can be selectively accumulated by serotonin-containing granules of platelets. Analysis of the fluorescence signal allows the estimation of the relative volume of the granules and the equilibrium coefficients for AO transport across the cytoplasm and granule membranes. The following results were obtained for human and rabbit platelets: the relative volumes of the granules were 14±1% and 29±2%, the ratios of intragranular-extracellular probe concentration were 2260±382 and 30,000±5500, and the cytoplasm-extracellular medium concentration ratios were 375±60 and 225±60, respectively.     

Effect of diabetes on the enzymes of the cholinergic system of the rat brain

Choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) activities were determined in several brain regions of normal and streptozotocin-induced diabetic rats. The diabetic rats exhibited significant increase in ChAT activity (p less than 0.05) in all brain regions studied except for the cortex and the midbrain. Meanwhile, the diabetes condition was associated with significant increase (p less than 0.05) in AChE activity of the bulbus olfactorius, medulla oblongata and cerebellum. These data suggest that uncontrolled diabetes is associated with significant alterations in the brain cholinergic systems.     

Role of the anomeric centre in sugar sweetness

Intensity-time studies of the sweetness of D-glucose solutions show that there are no major differences between alpha- and beta-anomers. Nor do the alpha- and beta-anomers exhibit any differences in apparent molar volumes. Contrary to previous reports, the anomeric centre of D-fructose may play no direct role in the sweetness response.     

Transglutaminase induction by various cell death and apoptosis pathways

Clarification of the molecular details of forms of natural cell death, including apoptosis, has become one of the most challenging issues of contemporary biomedical sciences. One of the effector elements of various cell death pathways is the covalent cross-linking of cellular proteins by transglutaminases. This review will discuss the accumulating data related to the induction and regulation of these enzymes, particularly of tissue type transglutaminase, in the molecular program of cell death. A wide range of signalling pathways can lead to the parallel induction of apoptosis and transglutaminase, providing a handle for better understanding the exact molecular interactions responsible for the mechanism of regulated cell death.