The ordered arrangement of hair follicles (Foit lines) and reception of a geomagnetic field

The authors offer the hypothesis of reception of a geomagnetic field based on the special properties of a mammal’s skin. It assumes that the ordered arrangement of hair follicles (Foit lines) can serve the pseudo-solenoid, in which under the action of external fields the currents starting the neuro-humoral mechanism of answer-back reactions are induced. According to this hypothesis, the magnitude of the generated afferent neuro-humoral signals depends on animal orientation concerning a vector of a geomagnetic field. There of there will be a larger or smaller degree of activation of hypothallamus-hypophysis-adrenal system (HHAS) which defines the adaptive status of an animal and, accordingly, adequacy of response to the set of external factors corresponds.

Rabbit heart can be “preconditioned” via transfer of coronary effluent

Brief myocardial ischemia not only evokes a local cardioprotective or “preconditioning” effect but also can render remote myocardium resistant to sustained ischemia. We propose the following hypotheses: remote protection is initiated by a humoral trigger; brief ischemia-reperfusion will result in release of the humoral trigger (possibly adenosine and/or norepinephrine) into the coronary effluent; and transfer of this effluent to a virgin acceptor heart will elicit cardioprotection. To test these concepts, effluent was collected during normal perfusion from donor-control hearts and during preconditioning ischemia-reperfusion from donor-preconditioned (PC) hearts. After reoxygenation occurred and aliquots for measurement of adenosine and norepinephrine content were harvested, effluent was transfused to acceptor-control and acceptor-PC hearts. All hearts then underwent 40 min of global ischemia and 60 min of reperfusion, and infarct size was delineated by tetrazolium staining. Mean infarct size was smaller in both donor- and acceptor-PC groups (9% of left ventricle) than in donor- and acceptor-control groups (36% and 34%; P < 0.01). Protection in acceptor-PC hearts could not, however, be attributed to adenosine or norepinephrine. Thus preconditioning-induced cardioprotection can be transferred between rabbit hearts by transfusion of coronary effluent. Although adenosine and norepinephrine are apparently not responsible, these results suggest that remote protection is initiated by a humoral mechanism.

Expression of vascular endothelial growth factor in pediatric and adult cerebral arteriovenous malformations: an immunocytochemical study

✓ Children and adults may differ with respect to their cerebral vasculature in both normal and pathological states. The authors have identified four pediatric patients in whom a cerebral arteriovenous malformation (AVM) recurred after surgery for removal of the AVM and in whom a normal postoperative angiogram had been obtained. This phenomenon has not been observed in adults. The propensity to regrow a cerebral AVM may reflect a less mature cerebral vasculature and a disregulated angiogenic process. Recently, attention has focused on vascular endothelial growth factor (VEGF) as a possible general mediator of angiogenesis in development and neoplasia. A retrospective immunocytochemical analysis of VEGF expression in AVM tissue was conducted to test the hypothesis that VEGF expression may be found in association with the regrowth of AVMs. The results demonstrate a high degree of astrocytic VEGF expression in four (100%) of four specimens from the initial operation in the children with recurrent AVMs as compared to one (14%) of seven nonrecurrent AVMs in the pediatric and two (25%) of eight adult specimens. All of the specimens from the first operation of the recurrent group demonstrate a clear association of cellular immunoreactivity to the abnormal blood vessels, a relationship that was not observed in the specimens from the nonrecurrent groups. These observations indicate that a humoral mechanism mediated by VEGF may play a role in AVM recurrence.

AN X-RAY STUDY OF THE INFLUENCE OF VASOACTIVE INTESTINAL POLYPEPTIDE AND SUBSTANCE P ON THE SECRETION OF GAS INTO THE SWIMBLADDER OF A TELEOST GADUS MORHUA

The rate of gas secretion into the swimbladder of the Atlantic cod Gadus morhua was studied with X-ray measurements of swimbladder size. A direct correlation was found between the area of the swimbladder in the X-ray photographs and the volume of the swimbladder. Removal of the swimbladder gas stimulates the fish to produce new gas, and the mean rate of refilling of the swimbladder in the cod was found to be 1.5 ml kg−1 h−1 during the first 24 h. The influence of drugs and of vagotomy on the rate of filling was measured. Gas secretion was completely inhibited by vagotomy and partly inhibited by injections of atropine or porcine vasoactive intestinal polypeptide (VIP). Substance P and VIP both increased the rate of secretion in atropinized fish, while 5-hydroxytryptamine (5-HT) and noradrenaline did not affect the rate of filling in either control or atropinized fish. Carbachol, VIP and substance P did not induce secretion in vagotomized fish, indicating that certain other fibres in the vagus might be necessary for gas secretion. It is concluded that a VIP-like and a substance-P-like peptide might be involved in the control of the secretion of gas in the cod swimbladder, VIP by a neuronal mechanism and substance P by a neuronal and/or humoral mechanism.