Gastric emptying of solid meals in diabetics

The gastric emptying rate of an isotopically labelled solid meal was compared in 29 insulin-dependent well-controlled diabetics and 18 normal controls. The diabetics were assessed for evidence of autonomic neuropathy. No significant difference in gastric emptying rate was found between controls and diabetics with or without autonomic neuropathy. Only three diabetics had greatly delayed gastric emptying, but in one of these the test had given a normal result on an earlier occasion.     

The Blalock-Taussig operation: the procedure of choice in the hypoxic infant with tetralogy of Fallot

An experimental model is presented enabling an analysis of the healing process of completely cut and re-sutured free segments of rabbit flexor tendons, kept avascular in a synovial milieu and completely isolated from adhesion formation. Under these conditions the cut tendons heal within a few weeks. It can be shown that this healing process is a result of intrinsic tendon cell activity only.     

Comparison of the temperature sensitivity of protein synthesis by cell-free systems from liver of rat and skate (Raja ocellata)

Studies were undertaken to determine the component(s) responsible for the temperature optimum characteristic of the protein-synthesizing system from skate and rat. 1. The macromolecular constituents of rat and skate liver ribosomes are compared. The number of ribosomal proteins is similar in the two species, although most proteins display different electrophoretic mobilities on polyacrylamide gels. The RNAs from the small subunit of skate and rat have similar sedimentation coefficients; however, the RNA from the large subunit of skate ribosomes appeared to be slight smaller than the comparable RNA from the rat. 2. Ribosomes from either rat or skate were capable of supporting poly(U)dependent polyphenylalanine synthesis with soluble factors from either species. 3. Maximal leucine incorporation directed by endogenous mRNA occurred at 35--40 degrees C with post-mitochondrial supernatant from the rat liver and at 20--30 degrees C with that from skate liver. 4. The characteristic temperature sensitivity of protein synthesis was dependent upon the source of cell sap and independent of the source of ribosomes. 5. Elongation factor 1 from both the rat and skate exhibited maximum activity at approx. 30 degrees C. 6. Phenylalanyl-tRNA synthetase from skate liver showed maximum activity at 30 degrees C while that from rat was maximally active at 37 degrees C. The rat enzyme, however, was active at 0--10 degrees C, at which temperature protein synthesis in the reconstructed rat system is virtually absent. 7. The protein-synthesizing capacity of the reconstituted system at various temperatures was closely correlated with the activity of Elongation factor 2 (translocase). Elongation factor 2 from rat liver displayed an optimum at 30 degrees C and lost all activity below 10 degrees C, while this same factor from skate liver showed an optimum at 20 degrees C and significant activity below 10 degrees C. At this low temperature the reconstituted skate liver system continued to exhibit the ability to synthesize protein. These studies suggest that Elongation factor 2 is the component responsible for determining the temperature at which the protein-synthesizing system displays its characteristic maximum activity.     

Electrophoretic studies of the cystic fibrosis ciliary inhibitor and its interaction with immunoglobulin G

The cystic fibrosis ciliary inhibitor (CFCI) has been partially purified from serum and plasma of cystic fibrosis (CF) homozygotes and heterozygotes, and from media of cultured fibroblasts derived from cystic fibrosis genotypes. Characterization and comparison of fractions containing the CFCI were carried out by polyacrylamide gel electrophoresis. Gel electrophoresis confirmed previous molecular weight estimations of 4,500 to 11,000 for the CFCI and provided an estimate of the number of proteins present in the fractions. Low molecular weight proteins from serum and media were combined with IgG preparations. No specific binding to IgG by the media fraction containing the CFCI could be demonstrated by the techniques employed. There was decreased binding of the low molecular weight serum fraction containing CFCI to native IgG molecules from cystic fibrosis patients as compared to IgG from normal individuals. However, IgG from CF individuals demonstrated increased binding of the cfci-containing low molecular weight serum fraction after gel filtration in the presence of guanidinium chloride. This suggests: 1) that very low concentrations of CFCI are present in media fractions; and 2) that native CF IgG cannot bind the low molecular weight CFCI fractions to the same degree as native IgG from normals or CF IgG that has been dissociated from non-covalently bound components.