The amount and the types of glycosaminoglycans (GAGs) present in human pancreatic carcinoma were examined and compared with those in normal pancreas. Human pancreatic carcinoma contained increased levels (4-fold) of total GAGs. Particularly, this carcinoma is characterized by a 12-fold increase of hyaluronan (HA) and a 22-fold increase in chondroitin sulfate (CS) content. CS in pancreatic carcinoma exhibited an altered disaccharide composition which is associated with marked increase of non-sulfated and 6-sulfated disaccharides. Dermatan sulfate (DS) was also increased (1.5-fold) in carcinoma, whereas heparan sulfate (HS), the major GAG of normal pancreas, becomes the minor GAG in pancreatic carcinoma without significant changes in the content and in molecular size. In all cases, the galactosaminoglycans (GalGAGs, i.e. CS and DS) derived from pancreatic carcinomas were of lower molecular size compared to those from normal pancreas. The results in this study indicate, for the first time, that human pancreatic carcinoma is characterized by highly increased amounts of HA and of a structurally altered CS.

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The aim of the present study was to examine the effect of acute plyometric exercise on indices of muscle damage and collagen breakdown. Nine untrained men performed an intense bout of plyometric jumping exercises (experimental group) and nine men remained at rest (control group). Seven days before and 24, 48, and 72 hours after plyometric exercise or rest, several physiological and biochemical indices of muscle damage and two biochemical indices of collagen damage were determined. No significant changes in concentric and eccentric peak torque of knee extensors and flexors or flexion and extension range of motion were found after the plyometric exercise. Delayed-onset muscle soreness increased 48 hours after exercise. Creatine kinase increased 48 and 72 hours post exercise, whereas lactate dehydrogenase increased 24, 48, and 72 hours post exercise. Serum hydroxyproline increased 24 hours post exercise, peaked at 48 hours, and remained elevated up to 72 hours post exercise. Hydroxylysine (which was measured only before exercise and at 48 hours) was found increased 48 hours post exercise. No differences were found in any physiological or biochemical index in the control group. Intense plyometric exercise increased muscle damage, delayed-onset muscle soreness, and serum indices of collagen breakdown without a concomitant decrease in the functional capacity of muscles. Hydroxyproline and hydroxylysine levels in serum seem promising measures for describing exercise-induced collagen degradation. Coaches need to keep in mind that by using plyometric activities, despite the increased muscle damage and collagen turnover that follow, it is not necessarily accompanied by decreases in skeletal muscle capacity.

In a cell-free system derived from Escherichiu coli, the reaction between A c [~H ] P~~-~R N A and puromycin (S) is inhibited by blasticidin S (I). In this reaction A c [~H ] P~~-~R N Ais part of the A~[~HlPhe-tRNA-poly(U)-ribosome complex (C). After preincubating the complex C with I and then adding S, the degree of inhibition is greater than that observed when C reacts with a mixture of S and I. Without preincubation, the inhibition is competitive giving a Ki of 2 x M. After preincubation the inhibition becomes of the mixed non-competitive type. A first-order kinetic analysis of the reaction between C and excess S, in the presence or in the absence of I, with or without preincubation, suggests that I acts as a modifier decreasing the catalytic rate constant of ribosomal peptidyltransferase (the putative enzyme that catalyzes the reaction between C and S). The effectiveness of I cannot be expressed by an equilibrium constant such as the above-mentioned Ki. A model is proposed which explains the results obtained. In this model, in the presence of I, C is converted to a modified species C *, which is still able to react with S but with a lower catalytic rate constant. This is a novel concept, in which the ribosome can be subjected to modulation of its activity by small ligands. It can be useful in studies on translational control of protein synthesis.It has been widely assumed that the interaction between the ribosome (R) and various inhibitors (I) of protein synthesis can be expressed by a simple equilibrium of the form R + I R1, and that the corresponding equilibrium constant (K,) is a measure of the potency of the inhibitor. This notion has prevailed for many years in most of the studies on inhibitors of protein synthesis. In the field of ribosomal topography attempts are made to map ribosomal sites based, again, on the assumption of simple equilibria [I, 21. The first indications that a simple equilibrium might express only the initial encounter between the ribosome and the inhibitor, and that subsequent events may lead to a modification of the ribosome, came from work with sparsomycin and spiramycin [3], which was confirmed in other laboratories [4, 51. Blasticidin S is an aminohexose pyrimidine nucleoside antibiotic, which inhibits protein synthesis. It specifically inhibits ribosomal peptidyltransferase [6, 71. The interest in blasticidin S is due to the fact that structurally it relates to puromycin and to the aminoacyladenylyl terminus of aminoacyl-tRNA; it has been used in studies involving other important inhibitors of protein synthesis, such as chloramphenicol [8 -101 and sparsomycin [I 11. However, the mechanism of action of blasticidin S, as well as that of chloramphenicol and of sparsomycin is still unclear. Blasticidin s has also been reported as an inhibitor of DNA synthesis [12].A model reaction, used frequently in studies on protein synthesis, is the puromycin reaction. Puromycin is utilized as Abbreviation. Complex C, the AcPhe-tRNA -poly(U) -ribosome complex. a substrate by the ribosomal pept...