Osteogenesis in cultures of limb mesenchymal cells

The results of previous reports demonstrated that osteoblasts develop in cultures derived from phenotypically unexpressive stage 24 chick limb mesenchymal cells. The observations reported here suggest that initial cell plating densities may provide environmental conditions deterministic to a particular limb phenotype. Quantitative microscopic studies, histochemical localization of calcium phosphate, and electron microscopy indicate that osteoblasts develop in cultures derived from stage 24 limb mesenchymal cells. Additionally, 1–3% of the cells from stage 24 limbs are associated with mineral deposits when plated at initial high densities (5 × 10⁶ cells per 35-mm culture dish), while more than 50% of the cells are associated with cartilage by Day 9. Cultures plated at intermediate seeding densities (between 2.0 and 2.5 × 10⁶ cells per 35-mm culture dish) have minimal cartilage development, and approximately 20% of the cells are associated with mineral by Day 9. Furthermore, cultures prepared from stage 31 limb mesenchymal cells form well-developed bone nodules with both osteoblasts and osteocytes present, but no cartilage. It is clear from these observations and from a consideration of the initiation of osteogenesisin vivo that the initiation of bone development in the limb is not associated with cartilage development. Based on these studies and observations on the effect of nutrient factors on phenotypic expression in culture, an hypothesis is presented relating differential vascularization and nutrient flow to the determination of limb phenotypesin vivo.     

Study of some oxidoreductases in nerve tissue culture]

A change in the activity of succinic dehydrogenase, of the NAD- and NADP-diaphorases was studied in the dissociated culture of the cerebellum of neonatal rats under the effect of immune serum of the animals with an experimental allergic pertussis encephalomyelitis. There was revealed an increase in the activity of oligodendrocytes following a 3-hour exposure with the immune serum and a reduction of the activity of the enzymes under study in the same cells after a 12-hour exposure of the cultures with the serum. In difference from oligodendrocytes, the astrocytes displayed a high activity of all the enzymes under study after a 12-hour exposure.     

Principles of insecticide action on mushroom cropping: incorporation into compost

A series of cropping experiments has demonstrated that mushroom yields show an approximate logistic response to a range of insecticide concentrations incorporated in the compost. This principle applies only to the cumulative yield at any flush, and the response of an individual flush is, therefore, related to the difference between two logistic curves. Increases in crop can thus occur in later flushes, partially compensating for earlier losses. With diazinon treatments, but not thionazin, some of this compensation was due to increases in the size of mushrooms. It is concluded that commercial applications of 50 ppm diazinon could cause up to 2–5 % reduction in crop and that 10 ppm thionazin may cause a 6% loss which must be weighed against the advantages of treatment. Suggestions are made for the design and interpretation of future trials.     

Intelligence and educational level in relation to body mass index of adult males.

In this study we explore the relationships between intelligence test score, educational level, and degree of body fatness. We collected data on intelligence test score, educational level, height, and weight from a sample of 26,274 young Danish men and computed body mass index (weight/height2) as a measure of fatness. Both intelligence test score and educational level had maximum values below the median for body mass index and declined monotonically thereafter. The decline was equal for test score and educational level and above 32 kg/m2 corresponded to almost half a standard deviation. These results are not readily explained by stigmatization of frank obesity, and other mechanisms, possibly genetic, may be responsible.