In the cat responses of afferent fibres in the inferior splanchnic nerves which innervate the colon and its mesentery were investigated upon intra-arterial bolus injection of bradykinin, of KCl- and of hypertonic NaCl-solution and upon ischaemia of the colon. One hundred and twenty-five units were analyzed. 1) Seventy-seven from 96 units with resting activity (80%) and 7 from 29 units without (24%) were excited by bradykinin. The exictation was present both when the colon wall contracted and when the contractions were prevented or when the colon was paralytic. 2) Fifty-two from 82 units with resting activity (67%) and 4 from 21 units without (19%) responded to KCl with short-lasting, high-frequency bursts. Injections of hypertonic NaCl-solutions had only small effects on the afferent units. 3) The responses of the units to distension of the colon (see [3]) and to the chemical stimuli were highly correlated. 4) Afferent units which responded to distension of the colon and to bradykinin were also excited by partial or complete ischaemia of the colon (produced by occlusion of both mesenteric arteries or of only the inferior mesenteric artery). During ischaemia the activity in the afferents increased and became burst-like. The response to distension of the colon increased in some of the afferent units. 5) Blood pressure responses to colon distension and to local bradykinin application also increased during ischaemia. 6) The results indicate that visceral afferent fibres from the colon in the inferior splanchnic nerves may be functionally homogeneous and may encode noxious stimuli applied to the colon.
A method is introduced for estimating acceleration, velocity and distance of longitudinal growth curves and it is illustrated by analysing human height growth. This approach, called kernel estimation, belongs to the class of smoothing methods and does not assume an a priori fixed functional model, and not even that one and the same model is applicable for all children. The examples presented show that acceleration curves might allow a better quantification of the mid-growth spurt (MS) and a more differentiated analysis of the pubertal spurt (PS). Accelerations are prone to follow random variations present in the data, and parameters defined in terms of acceleration are, therefore, validated by a comparison with parameters defined in terms of velocity. Our non-parametric-curve-fitting approach is also compared with parametric fitting via a model suggested by Preece and Baines (1978).
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