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Biomedical subjects

M Horst

Publications and source records attributed to M Horst.

75 records · Page 5Linked to original sources
PubMedDate not supplied

On the interaction of bull and boar acrosins with the zona pellucida of different mammalian species in vitro.

Acrosin was prepared from boar and bull spermatozoa and its lytic effect in vitro on the zona pellucida of mouse, golden hamster, rabbit, pig and cow was investigated. Depending upon the species studied, ovarian oocytes, ovulated oocytes and preimplantation embryos were obtained for the experiments. While in golden hamster and rabbit the zona pellucida was removed by both acrosins, this effect was absent for bull acrosin in cow and mouse eggs and for boar acrosin in pig and mouse eggs. In those species in which the zona pellucida was not removed by the acrosins after an incubation period of 2 hours even a prolongation up to 24 hours with higher amounts of acrosin, the addition of acrosomal extracts to the incubation buffer (Tyrode solution pH 7.2) or an increase of the pH value up to 8.6 of the acrosin solution had no effect upon the zona pellucida. Our results indicate that at least in vitro, acrosin does not possess the capacity to lyse the zona pellucida in a species specific fashion. Since the lytic effect of boar and bull acrosin on the zona pellucida of ovarian oocytes and preimplantation embryos is not different from that on ovulated oocytes it can be assumed that neither the maturation of the zona pellucida during oogenesis nor its modification after fertilization, change the susceptibility of the zona pellucida to acrosin digestion.

Acrosin↗
PubMedDate not supplied

Use of urea kinetics in the nutritional care of the acutely ill patient.

In acutely ill patients nitrogen balance is often assessed clinically from measurements of protein intake and urinary urea nitrogen. We have utilized urea kinetic modeling to measure urea generation rates, protein catabolic rates and nitrogen balance in 19 acutely ill patients with varying degrees of renal dysfunction and have studied the effect of varying caloric intake on protein balance during a period of fixed protein intake. In patients with measured creatinine clearances equal to or greater than 50 ml/min there was a highly significant correlation between nitrogen balance estimates derived from urea kinetic modeling and those obtained from urinary urea nitrogen (R = 0.939; p less than 0.001). When creatinine clearance measurements were between 20 to 50 ml/min the correlation between the two estimates was poorer (R = 0.337; p less than 0.001). In patients whose creatinine clearance was below 20 ml/min the correlation between measurements was worse still (R = 0.229; p less than 0.002). To determine the effects of increasing caloric intake on protein catabolic rate seven acutely ill patients were studied. When caloric intake was increased from 27.8 to 34.2 kcal/kg/day while on a fixed protein intake of 1.27 g/kg/day there was a significant fall in protein catabolic rate from 1.39 to 0.99 g/kg/day (p less than 0.002). As urea kinetic modeling takes into account changes in blood urea nitrogen, extrarenal losses of urea and the urinary urea pool, it is the preferred method for measuring protein balance in acutely ill patients particularly those with poor renal function. Serial monitoring of protein catabolic rates permits easy continuous assessment of the effect of increasing caloric intake on protein sparing during parenteral hyperalimentation.

Acute Disease↗