Blood metabolites and hormones--especially glucose and insulin--in veal calves: effects of age and nutrition.

Veal calves often develop insulin resistance, hyperglycaemia and glucosuria. We have studied effects of age and nutrition on blood metabolites and hormones, with major emphasis on glucose and insulin, in four groups of veal calves from 66-69 kg until slaughter at 175-196 kg. Calves were fed milk replacers which differed with respect to lactose, total sugar, protein and fat content. Mean intakes in groups 1, 2, 3 and 4 of lactose (1.24, 1.08, 0.95 and 0.66 kg/d), total sugar (1.27, 1.10, 1.01 and 96 kg/d), crude protein (0.40, 0.48, 0.65 and 0.49 kg/d) and crude fat (0.32, 0.31, 0.37 and 0.46 kg/d) were different. Average daily gains were 1.46-1.49 kg and feed/gain ratios were 1.49-1.61 kg/kg. Glucose and insulin concentrations were not associated with protein and fat intakes, but followed lactose and total sugar intakes, albeit differently at the start and end of the growth trial. Thus, insulin concentrations were higher (P < 0.05) at the end than at start of the growth trial in all 4 groups, whereas glucose concentrations increased (P < 0.05) with increasing age in only group 2. In conclusion, lactose and total sugar intakes affected the degree of hyperglycaemia and modified hyperinsulinemia at a given age, but the age-dependent rise of insulin concentrations could not be explained by hyperglycaemia alone.

Solubilization and characterisation of the cholecystokininB binding site from pig cerebral cortex.

Cholecystokinin (CCK) binding sites were solubilized from pig cerebral cortical membranes with digitonin (2%, w/v) in the presence of Na+ (120 mM) and Mg2+ (5 mM). Scatchard plot transformation of equilibrium binding data obtained with 125I-CCK-8S gave an apparent dissociation constant (Kd) of 0.6 nM, comparable to that obtained in membranes in the presence of these cations. Hill coefficients close to unity suggested the presence of a single population of receptor sites. Competitive inhibition studies with pentagastrin, gastrin(1-17)S and the CCKA receptor antagonist L-364,718 indicated that the solubilized receptor sites were of the B-type (CCKB), with the same pharmacological profile as that observed in membranes. Optimal specific binding of 125I-CCK-8S to membrane-bound and solubilized receptors was obtained in the presence of divalent cations. Both the membrane-bound and the solubilized receptor activity were attenuated by guanylyl-imidodiphosphate (Gpp(NH)p) indicating that the brain CCKB receptors are coupled to G proteins.

Z-DNA-binding proteins from bull testis.

Three Z-DNA-binding proteins of Mr 31, 33 and 58 kD were isolated from mature bull testis. They were obtained in a native state suitable for binding studies. These are the first examples of Z-DNA-binding proteins from a mammalian tissue. Purification involved tissue extraction with 0.35 M NaCl, cation exchange chromatography on CM-Trisacryl M and two consecutive anion exchange FPLC runs on Mono Q. The proteins appeared virtually homogeneous by anion exchange FPLC, SDS polyacrylamide gel electrophoresis and reverse phase HPLC (58 kD protein only). Yields from 50 g of testis tissue were: 31 kD protein, 40 micrograms; 33 kD protein, 100 micrograms; and 58 kD protein, 150 micrograms. Z-DNA binding was determined by Scatchard analysis of filter binding data using brominated poly(dG-dC).poly(dG-dC) as a conformation-specific ligand. Dissociation constants (Kz, in mol nucleotide/liter) were: 31 kD protein, 7 X 10(-7) M; 33 kD protein, 8 X 10(-7) M; 58 kD protein, 6 X 10(-8) M (primary binding site) and 6 X 10(-7) M (secondary binding site). B-DNA binding to poly(dG-dC).poly(dG-dG) was too low for reliable determination under the conditions of assay. This attested to a high degree of conformational specificity of the three proteins. The 58 kD protein bound Z-DNA at the primary site with an affinity almost equivalent to that of a polyclonal anti-Z-DNA antiserum raised in a rabbit (Kz, 4 X 10(-8) M).