[Changes in variability of heart rate and sudden death detected during ambulatory electrocardiography]. / Alteraciones de la variabilidad de la frecuencia cardiaca y muerte súbita detectada durante electrocardiografía ambulatoria.

Two patients with ischemic heart disease had sudden death detected by means of ambulatory electrocardiography; the first patient had ventricular tachycardia-asystole and the second bradycardia-asystole without mediating a ventricular tachyarrhythmia. In both cases the autonomic function of the heart was determined, by means of the heart rate variability for spectral analysis and for time domain analysis. An important decrease in heart rate variability in the patient with tachyarrhythmia was appreciated, more pronounced in the hour previous to his death. On the other hand, in the patient with bradycardia-asystole there was increased heart rate variability. This suggests different neural influences in both patients for the development of sudden death: an alteration in the autonomic function of the heart in the patient with ventricular tachyarrhythmias, related to a depressed parasympathetic tone. In the patient with bradycardia-asystole, the parasympathetic tone was accentuated.

Blood responses of calves fed milk substitutes containing hydrolyzed fish protein and lime-treated corn flour.

Two experiments involving 3- to 5-d-old dairy calves were carried out. In Experiment 1, lime-treated corn flour (Nixtamal) supplied 50 to 100% of carbohydrates in a milk substitute based on sodium caseinate, lard, and cerelose. In Experiment 2, partially hydrolyzed fish protein concentrate replaced 50% of 67% of proteins in milk substitutes based on skim milk powder, lard, and 35% Nixtamal. Increasing the proportion of carbohydrates supplied by Nixtamal was associated with a linear decrease of postprandial serum glucose and insulin. Postprandial fluctuations in blood glucose were less in calves fed Nixtamal than in controls. Nixtamal probably was trapped within the casein clot in the abomasum, leading to delayed rate of passage of Nixtamal carbohydrates into the intestine. Replacing skim milk protein with hydrolyzed fish protein in diets containing Nixtamal had no effect on blood glucose or insulin but elevated free essential amino acids, which promoted glucagon secretion. More uniform concentrations of blood essential amino acids and glucose were related to lower blood urea at 54 d in calves fed diets based on hydrolyzed fish protein and Nixtamal, than that of control calves. It is suggested that more uniform postprandial blood glucose concentrations might reduce amino acid degradation for energy purposes and stimulate protein synthesis. Young dairy calves may adapt to milk substitutes based on Nixtamal and hydrolyzed fish protein despite changes in the concentration patterns of several blood components.

Replacement of skimmed milk with hydrolyzed fish protein and Nixtamal in milk substitutes for dairy calves.

Two experiments were conducted with 3- to 5-d-old Holstein male calves. In Experiment 1, 15 calves were assigned to three dietary treatments. The control diet was based on sodium caseinate, lard, and cerelose. In the other diets, either 50% or all carbohydrates were replaced by lime-treated corn flour (Nixtamal). In Experiment 2, 35 calves were assigned to dietary treatments in which 0, 50, or 67% low heat skimmed milk protein was replaced by hydrolyzed fish protein; for the replacement diets, Nixtamal was incorporated at 25 or 35% of the dry matter. Control diet protein was entirely from skimmed milk. Milk substitutes provided the only feed during the 8-wk experiment. In Experiment 1, body weight gain and feed efficiency declined when Nixtamal completely replaced skimmed milk but remained unchanged at 50% substitution. Substitution of Nixtamal for skimmed milk powder decreased nitrogen and carbohydrate digestibility; but digestibility improved with age. In Experiment 2, replacing up to 67% of skimmed milk protein with partially hydrolyzed fish protein concentrate had no effect on body weight gain but decreased feed efficiency linearly at 8 wk and reduced dry matter, nitrogen, and fat digestibility. Nixtamal can replace up to 50% of skimmed milk carbohydrates without detrimental effect on growth rate, feed efficiency, and diarrhea, but digestibility might be reduced. Concurrent replacement of up to 67% of skimmed milk protein with partially hydrolysed fish protein concentrate would be feasible for newborn calves gaining 450 g/d, despite lower nitrogen digestibility.