The enhanced AVSH algorithm reduces %VP compared with standard AVSH in patients with intermittent AV block.

Human plasma somatostatin-like immunoreactivity (SLI) is heterogeneous. Moreover, human plasma contains a somatostatin-binding protein, enzymes that degrade the peptide, and other poorly characterized substances that interfere in radioimmunoassays of the peptide. Previously described extraction methods only partially circumvent these problems and generally result in less than adequate recovery. The present studies were therefore undertaken to determine whether gel filtration of plasma could be used to avoid these difficulties and provide a means for radioimmunoassay of plasma somatostatin in man. Gel filtration (Sephadex G25) of human plasma and subsequent radioimmunoassay of column eluates using five different antisera uniformly demonstrated two fractions of SLI in plasma. One fraction (peak I) eluted in the void volume and had an apparent molecular weight in excess of 150,000 daltons; this material comprised most of the plasma SLI, did not dilute in parallel with synthetic somatostatin, and decreased immunoprecipitability of both N-tyrosine-and tyrosine-11-125 l somatostatin. The second fraction (peak II) coeluted with synthetic somatostatin (apparent mol. wt. 1600 daltons), diluted in parallel with synthetic somatostatin, and did not appreciably degrade either 125 l-tyrosylated analogue. Synthetic somatostatin added to plasma was recovered nearly completely (95 ± 3%) in peak II SLI. Infused synthetic somatostatin increased peak II SLI but did not alter peak I SLI. These results demonstrate that gel chromatography of human plasma before assay can be used to circumvent problems of immunoheterogeneity, degradation, and nonspecific interference while providing adequate recovery. With this method, mean plasma somatostatin concentrations (peak II SLI) in postabsorptive normal volunteers ranged from approximately 40 to 100 pg/ml, depending on the antibody system used. These concentrations (3-6 x 10~1 1 M) are of similar magnitude to those

In an attempt to clarify the pathogenesis of the disturbed calcium metabolism which sometimes follows partial gastrectomy, we determined plasma 25-hydroxyvitamin D (25-OH-D) concentrations and urinary cyclic 3',5'-adenosine monophosphate (cAMP) excretion in patients who had previously undergone Billroth II gastrectomy and who were without clinical evidence of bone disease. In 17 Billroth II patients plasma 25-OH-D concentrations were reduced (12.6 +/- 4.6 ng/ml, mean +/- SD) compared to values in 17 control patients with diseases not affecting calcium metabolism (31.6 +/- 12.9 ng/ml, P less than 0.001). Urinary cAMP excretion, in part reflecting parathyroid function, was higher in 17 Billroth II patients (5.0 +/- 2.5 micronmol/day) than in the control patients (2.6 +/- 1.3 micronmol/day, P less than 0.001). These results suggest impaired nutrition of vitamin D and secondary hyperparathyroidism in Billroth II patients. While the cause of this phenomenon is unclear, it may contribute to the disturbance of calcium metabolism in patients who have had subtotal gastrectomy.

Recently we observed an increased urinary cAMP excretion in diabetics with symptomatic hypoglycemia during insulin treatment (v. Lilienfeld• Toal and WiIlms, in press). In order to show that hypoglycemia leads to changes of plasma cAMP concentration (pcAMP) in these patients, we studied the effect of I. V. insulin administration (0.15 U /kg BW) in 12 insulin dependent diabetics (age range: 18-53 years; therapeutic insulin dose: 22-76 U/day). In addition we sought evidence of changes in renin release by measuring the plasma renin activity (PRA) which increases during insulin induced hypoglycemia in normals (Lowdes, Frazer and Liddie 1975).