Inhibition and axial deviation of limb regeneration in the newt by means of a digit implanted into the amputated limb

This research was designed to follow up the observation of Thornton and Kraemer ('51) that regressed, denervated limbs of Ambystoma larvae will not regenerate upon reinnervation if all digits on the limbs were not completely resorbed. The object of this experiment was to determine whether the presence of an apical structure, protruding past the amputation surface, would affect the regenerative process. Both forearms of adult newts were amputated midway between the elbow and the wrist. One limb served as a normal regeneration control, and in the other limb the third digit from the removed hand was implanted in place of the removed radius, so that the three distal phalangeal segments protruded past the plane of amputation. Blastema formation in the experimental limbs was delayed by several weeks as compared with control limbs. Approximately one third of the experimental limbs did not regenerate. The regenerates that did form were strongly deviated (45-90 degrees) radially from the longitudinal axis of the limb. Experimental analysis showed that the delay in regeneration is due largely to the projecting part of the digit. The radial deviation of the regenerates is not due to the digital implant, but rather to the removal of the radius. Trauma alone does not account for this phenomenon.     

Glomerular adaptations to chronic dietary salt restriction or excess

Micropuncture studies were performed in 33 Munich-Wistar rats maintained chronically either on dietary NaCl restriction (group 1) or excess (group 2). Values for single nephron (SN) and total kidney glomerular filtration rate (GFR) were identical in both groups. Nevertheless, because of preferential efferent vasoconstriction, glomerular capillary hydraulic pressure (PGC) was higher in group 1, offsetting the lower initial glomerular plasma flow rate (QA) also found in group 1. The pressor response to infusion of exogenous angiotensin II (AII) was less in group 1 than in group 2, suggesting that vascular receptors for AII may have been occupied by endogenous hormone, the latter leading to the efferent arteriolar vasoconstriction. In addition to AII, prostaglandins also appear to be involved in the adaptations of the glomerular microcirculation to chronic variations in salt intake. In group 1, indomethacin or meclofenamate infusion mimicked exogenous AII, causing declines in QA and SNGFR. These changes were lacking in group 2. Because of relative contraction of plasma volume, the vasodilatory effects of prostaglandins appear to be needed in low salt animals to sustain SNGFR and QA. In the high salt group, however, since plasma volume is not contracted, maintenance of SNGFR and QA appears to be less critically dependent on endogenous prostaglandins.     

Allergic contact dermatitis to quinones in Paphiopedilum haynaldianum (Orchidaceae)

An eczematous eruption developed on the hands and forearms of a 68-year-old man after frequent contact with homebred specimens of the lady slipper Paphiopedilum haynaldianum. Patch tests with leaves, petals, and stems, as well as with two quinones isolated from the plant by thin-layer chromatography, gave strongly positive reactions. The results demonstrated that the recurrent skin lesions were the expression of an allergic contact dermatitis due to the quinoid constitutnets, which are the main contact allergens in this orchid species.     

Plasma noradrenaline correlates to sympathetic muscle nerve activity in normotensive man

Recordings of multiunit sympathetic activity were made in muscle branches of the peroneal nerve in 22 healthy subjects at rest in recumbent position. Nerve activity was quantitated in terms of burst incidence (number of pulse synchronous sympathetic bursts per 100 heart beats or per min). In a separate session, 4-45 months later, blood was drawn from an antecubital vein for noradrenaline analysis. Both sympathetic activity and plasma concentrations of noradrenaline varied widely between subjects and both parameters increased with age. There was a significant positive correlation between a subject's level of sympathetic activity and his plasma concentration of noradrenaline. It is suggested that overflow of transmitter from sympathetic terminals in muscles contributes significantly to plasma levels of noradrenaline at rest.