Genetic studies of coliphage P1. III. Extended genetic map

An extensive genetic map of coliphage P1 has been constructed for 113 amber mutants, using primarily a modification of the conventional complementation spot test. These spot tests failed to classify the mutants into cistrons, but when they were quantitated they permitted assignment of the mutants into 10 linkage clusters. Furthermore, a linear order could be deduced for most of the mutants within each cluster. This strongly suggested that recombination was the predominant event generating plaques and that, for the practical purpose of rapid genetic mapping, such spot tests could be considered as a series of two-factor crosses. Six of the 10 linkage clusters correlated with the P1 genetic map established by Scott (1968). The locations of the remaining four clusters were determined by three-factor crosses and by prophage deletion mapping. The nonrandom occurrence of termini for 14 deletion prophages, which we established previously (Walker and Walker, 1975), and the coincidence of these termini with five out of ten regions demarcating the linkage clusters are discussed. Complementation tests in liquid frequently gave ambiguous results. Therefore, cistron designations were not assigned.     

Cryosurgery of the ureter in dogs

The effect of cryosurgery on the ureter has been studied in dogs. A single 1- or 2-min cryosurgical exposure produced stricture in two of eight animals. A tumoricidal cryosrugical dose consisting of three, 2-min exposures caused stricture in six of eight dogs. Histopathologic examination of the ureter after repetitive cryosurgery showed progressive, persistent loss of smooth muscle, fibrosis of the lamina propria, and early loss with subsequent regeneration of the transitional epithelium. Although there was no loss of ureteral integrity, the possibility of permanent ureteral damage should be considered with the use of cryosurgery.     

Current management of digitalis intoxication

Of the commonly used drugs, digitalis has one of the highest therapeutic-toxic ratios. Mortality is significantly increased in the 20% to 30% of patients on digitalis who are in a toxic state when admitted to the hospital. Successful use of digitalis depends on avoidance of its use in situations likely to result in toxicity; recognition of the signs, symptoms, and electrocardiographic findings of digitalis intoxication; and stopping digitalis completely as the initial treatment of digitalis intoxication.     

Human thyroid adenyl cyclase-stimulating activity in immunoglobulin G of patients with Graves' disease

We have studied the characteristics of the stimulation of adenyl cyclase (AC) activity in human thyroid plasma membranes by thyroid-stimulating hormone (TSH) and by immunoglobulin G (IgG) from the sera of patients with Graves' disease. AC activity was measured as adenosine 3',5'-cyclic monophosphate (cAMP) generated by membranes in a 10 minute incubation. IgG from two patients with Graves' disease possessed particularly potent human thyroid AC-stimulating activity; the dose-response curves with these IgGs were essentially parallel to those obtained with TSH. As little as 30 mug of the IgG of one patient with Graves' disease or 8 muU of TSH caused significant AC stimulation. A Lineweaver-Burk plot of the data suggested similarity in the site of action of both TSH and human thyroid adenyl cyclase stimulator (HTACS) in Graves' IgG. Submaximal doses of HTACS and TSH had additive effects on AC stimulation, but a large dose of a Graves' IgG with potent AC stimulating activity did not enhance AC stimulation by a maximal dose of TSH. The effect of HTACS on AC was slower in onset and longer in duration than an equipotent dose of TSH. HTACS was detectable in IgGs of 9 of 15 untreated hyperthyroid Graves' disease patients; its concentration, however, did not correlate significantly with tests of thyroid function, nor with long-acting thyroid stimulator (LATS) activity. In another 11 treated patients with Graves' disease, selected for the presence of LATS, HTACS and LATS were significantly correlated. We observed no inhibition of LATS activity in a Graves' IgG chosen for such testing because of its high titer of HTACS and no detectable LATS. However, an inhibitor of HTACS was detected in 2 of 4 IgGs; one of these two IgGs also inhibited AC stimulation by TSH. Conclusions: 1) Some Graves' disease IgGs contain a human thyroid AC stimulator (HTACS), probably different from LATS. 2) HTACS may act via a common pathway with TSH; it differs from TSH, however, in having a slower onset and a greater effect during more prolonged incubation with plasma membranes. 3) There is also an inhibitor of HTACS activity in some Graves' disease IgGs.     

Intra-arterial sympathetic blockade in the treatment of clinical frostbite

Regional medical sympathectomy achieved by the intra-arterial injection of reserpine appeared to be of benefit in the treatment of five patients with acute or chronic frostbite injuries. Clinical improvement was associated with a significant increase in arteriographically determined regional perfusion.