PubMed · 4159991
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G Howitt, D J Rowlands. 1966-03-19. Beta-sympathetic blockade in hyperthyroidism.. https://doi.org/10.1016/s0140-6736(66)90825-7
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In order to assess the possible effects of sleep states on cerebral haemodynamics in healthy term infants, we measured cerebral oxyhaemoglobin, deoxyhaemoglobin and total haemoglobin concentration using near infrared spectroscopy. Thirty-seven sleep state changes in seventeen infants (gestational age: 37 to 41 4/7 weeks), aged between two and eight days were continuously registrated during 1-3 h. Transcutaneous PaO2, PaCO2, arterial O2 saturation and heart rate were simultaneously recorded and sleep states were clinically defined. There was a close relationship between sleep state changes and changes in total cerebral haemoglobin concentration, which increased from active to quiet sleep and decreased from quiet to active sleep. Changes in total cerebral haemoglobin were due, in the most part, to changes in the cerebral oxyhaemoglobin concentration. In conclusion, sleep states influence the cerebral haemoglobin concentration. Studies on cerebral haemodynamics should take sleep state into account in term newborn infants.
There are many examples of branching networks in biology. Examples include the structure of plants and trees as well as cardiovascular and bronchial systems. In many cases these networks are self-similar and exhibit fractal scaling. In this paper we introduce the Tokunaga taxonomy for the side branching of networks and his parameterization of self-similar side-branching. We introduce several examples of deterministic branching networks and show that constructions with the same fractal dimension can have different side-branching parameters. As an example of stochastic-branching in biology we consider the vein structure of a leaf. We show that the vein structure of the leaf and river networks have nearly identical side branching statistics. We introduce diffusion limited aggregation (DLA) clusters. These clusters also exhibit Tokunaga side-branching statistics. We consider several alternative explanations for why leaves, river networks, and DLA clusters have similar side-branching statistics. We also consider the allometric scaling relation between metabolic rate and the mass of species in terms of a cardiovascular system with Tokunaga statistics. We find reasonably good agreement between the observed scaling exponent, approximately 0.75, and our model for a range of values of the fractal dimension of the network and the blood flow resistance parameter.
Hypertonic-hyperoncotic solutions are a supplementary possibility in the acute treatment of hypovolemia. The main mechanism of action of this solution is, induced by the tonicity of the infusion (approximately 2400 mOsm/l), the transcapillary fluid shift from the intracellular and interstitial to the intravascular compartment. Additionally the fluidity of blood is improved (due to an increase in the diameter of the capillaries), the adherence of leucocytes to the endothelial wall is reduced, and the arteriolar vasomotion is restarted. Due to the available prehospital and clinical results it can be concluded, that hypertonic-hyperoncotic solutions offer advantages compared to conventional fluid therapy regimes: rapid stabilization of hemodynamics, reduction of posttraumatic volume deficiency, of posttraumatic edema and of posttraumatic complications and an improvement of the outcome of the patients. If the therapeutic recommendations are followed, such as a dose of 4 ml/kg body weight, infusion time of about 3-5 minutes and after the end of the infusion application of colloids or crystalloids in an amount as needed, no side effects will occur. Only immediately after the end of infusion sodium, chloride and osmolarity will slightly increase, however these parameters will normalize within the first posttraumatic day. Hypertonic-hyperoncotic solutions are trigger-solutions, as with the infusion of these types of solution it is possible to restore hemodynamics adequately and to prevent shock-induced complications.