Differentiating abilities of avian somatopleural mesoderm.

Quail-to-chick grafting experiments were performed on 2-day embryos in order to test the differentiating abilities of the somatopleure. After orthotopic and heterotopic transplatations of different parts of quail somatopleural mesoderm into chick embryos it is demonstrated that avian somatopleural cells differentiate into skeletal elements, smooth muscles, tendons and connective tissues. However, skeletal muscle fibres do not originate from somatopleural cells.     

Structure specificity of some immunoadjuvant synthetic glycopeptides.

The immunoadjuvant activity of muramyl dipeptide seems to be critically dependent on the type of substitution of the gamma-carboxyl group of the D-isoglutamine residue. Moreover the nonapeptide L-Ala-D-isoGlu-L-lys-D-Ala-(Gly)5-OME also shows a definite effect.     

Skeletal muscle capillary densities during reactive hyperemia

Reactive hyperemia was induced in hindlimbs of rats by occlusion of the femoral artery. Using fluorescein dye as a peripheral vascular marker, we observed that there was an increase in the number of flowing capillaries supplying the muscle fibres following release of the occlusion. The results indicate that the number of flowing capillaries is not dependent on the duration of occlusion (2-10 min).     

Hepatic blood flow in acute myocardial ischemia

Hepatic blood flow was monitored in cats during myocardial ischemia (MI). Increased plasma CPK activity, the S-T segment of the electrocardiogram, and hepatic flow was reduced by 5 h to 40% of control. The results suggest that MI can influence organs distant from the original ischemic episode.     

Effect of hormones on adenyl cyclase activity of rabbit mammary gland in vitro

Ovarian hormones namely beta-estradiol and progesterone were observed to stimulate the activity of adenyl cyclase of the mammary gland from pregnant rabbit in vitro, unlike the lactating tissue where it was inhibited. On the other hand, non-ovarian hormones like hydrocortisone, prolactin and insulin did not have a similar effect on this enzyme.     

Acute stress reduces the sensitivity of the vasculature to sympathetic control

Vascular smooth muscle from rabbits subjected to acute severe stress exhibits decreased sensitivity to sympathetic regulation. Stimulation of the sympathetic innervation of isolated vascular segments resulted in a similar subsensitivity as did exposure to norepinephrine (NE) but not histamine. Periodic contraction of these segments caused an increase in their maximum ability to contract independent of the constrictor procedure used. These results suggest that the increase in sympathetically mediated NE release that occurs in stress and some other pathological conditions may result in a blunting of neural control and possibly resistance to certain therapeutic agents.     

Chromatin fluorescence by pyronin staining

Human, chicken and mouse cells from different tissues show a bright red-orange fluorescence of the chromatin after staining with pyronin Y. The possibility that intercalation of the dye into double helical nucleic acids accounts for this fluorescence pattern is briefly discussed.     

Cell size and cell division of the anterior pituitary: time course in the growing rat

Pituitary cells increase their numbers more than 3-fold during the 1st 10 days of life while maintaining the same cell size ratios. In the 25-day-old animal, the rate of cell division slows and there is a slight increase in the number of large cells. An increase in adult weight is attributed to hyperplasia and a shift to a population of larger cells.     

A note on the mechanism of action of UV-irradiation of amphibian embryos

The actions on amphibian embryos of UV-irradiation, exposure to Li+ or exposure to ouabain show interesting parallels with their effects on spontaneous release at the presynaptic terminals of the neuromuscular junction. It is suggested that these treatments serve to raise intracellular Ca2+ ([Ca2+]i) in these examples, and that UV-promoted abnormalities in embryogenesis are a consequence of changes in [Ca2+]i at critical stages in development.     

The effect of lidocaine on the secretion induced by cholera toxin in the cat small intestine

The intraluminal administration of lidocaine, a local anaesthetic agent, inhibits the net loss of fluid into the intestinal lumen produced by cholera toxin in the cat. It is suggested that the activation of a nervous reflex is involved in the pathogenesis of cholera.