Coronary thrombosis in myocardial infarction: Report of a workshop on the role of coronary thrombosis in the pathogenesis of acute myocardial infarction

In recent years the widely held concept that coronary thrombi cause myocardial infarcts has been seriously questioned. On the basis of pathologic studies, several reports have suggested that coronary thrombi do not cause infarcts but instead are the result of infarction. Should these findings become generally substantiated, the antithrombotic approach to the prevention and therapy of ischemic heart disease must be revised. This workshop was organized to examine more closely this issue and to sort out reasons for such divergent views of the role of thrombosis in the pathogenesis of myocardial infarction.     

Effects of insulin at two dose levels on gluconeogenesis from alanine in fasting man

We have determined the effect of insulin infused at 1 and 5 mU/kg/min on gluconeogenesis from alanine in 48-hr fasted men. The conversion of alanine to glucose was measured by the arterial-hepatic venous catheterization technique combined with the infusion of ¹⁴C-alanine. During insulin infusion, euglycemia was maintained by variable glucose infusion. When insulin was infused at 1 mU/kg/min the net splanchnic production of ¹⁴C-glucose was suppressed by 80% but glucagon infused at the end of the study resulted in substantial release of ¹⁴C-glucose from the liver suggesting marked accumulation of labeled glucose in glycogen. When insulin was infused at 5 mU/kg/min the splanchnic release of ¹⁴C-glucose was also markedly suppressed but in contrast to the lower insulin dose very little labeled glucose accumulated in glycogen. Neither the high nor the low dose insulin infusion had any effect on net splanchnic alanine uptake and plasma glucagon levels fell by 35% in both protocols. These data demonstrate that in 48-hr fasted man, (1) a small increment in insulin concentration will suppress glucose production but mostly by diverting the newly formed glucose into glycogen; (2) at higher concentrations, insulin will inhibit glucose production mainly by suppressing gluconeogenesis; and (3) this insulin-induced suppression of gluconeogenesis is due to an intrahepatic effect rather than an effect on the splanchnic extraction of alanine.     

Analysis of non-histone chromatin proteins in porcine malignant hyperthermia

Non-histone chromatin proteins (NHCP) were isolated from skeletal muscle, left ventricle and liver of swine susceptible to malignant hyperthermia and from controls. These proteins were extracted with phenol buffers and fractionated by polyacrylamide gel electrophoresis. Isoelectrofocusing gel electrophoresis revealed quantitative differences in NHCP from skeletal muscle between disease and control groups. The high resolution of proteins by two-dimensional polyacrylamide gel electrophoresis showed a relative similarity between skeletal muscle, heart and liver although some differences could be discerned. Non-histone chromatin proteins of molecular weight 35,000–45,000, focusing between pH 7 and 9, were increased in skeletal muscle nuclei derived from malignant hyperthermia-susceptible swine. These proteins appear to be important in the maturation of messenger RNA. No alterations were seen in either heart or liver. We conclude that an increase in NHCP which is associated with the processing of messenger RNA, may be important in the phenotypic expression in skeletal muscle of malignant hyperthermia in swine.     

Heterochromatic variants and their association with neoplasias. I. Chronic and acute leukemia

C-banding studies of the heteromorphism of chromosomes #1, #9, and #16 were performed in 120 leukemic patients: 56 with chronic myelocytic leukemia (CML), 45 with acute lymphoblastic leukemia (ALL), and 19 with acute nonlymphoblastic leukemia (ANLL). No differences were found among patients and controls with regard to sex. Our data showed a significant increase of polymorphism in chromosome #1 in the three neoplastic groups; the heterochromatic variant preferentially involved 1qh-, whereas there were no significant differences in heteromorphism in chromosomes #9 and #16.     

Subannular Mitral Prosthesis in Aortic Position

Björk-Shiley subannular mitral prostheses have been used in the aortic position in 36 patients with calcific aortic annulus. We believe that the flange in the sewing ring of these prostheses offers added protection against perivalvular leakage; over an 18-month period there have been no instances of periprosthetic leakage in these patients.