Amplified migration inhibition effect

Upon exposure to specific antigen in tissue culture, sensitive lymphocytes released macrophage migration inhibition factor and other lymphokines into the supernatant culture medium. Migration of peritoneal macrophages from nonsensitive animals was inhibited in the presence of such supernatants. However, with previous techniques it was found that an inhibitory effect was present at only low low titers (less than 10(2)). It is therfore of great interest that by increasing cellular density, the total number of cells being kept constant, inhibitory activity can be amplified by a factor as great as 10(10). This amplification was observed only when lymphocytes and macrophages were loosely packed, as by spontaneous sedimentation in a conical test tube. The effect was abolished by dispersing the cell suspension in a flat-bottomed flask or, alternatively, by shaking the test tube so that intimate prolonged intercellular contact was prevented.     

The effects of training specific mnemonics on the metamnemonic efficiency of retarded children

On examination of the thumbs of 20 dissected preparations of ligaments and joints, of ten dry skeletons and of a number of living hands, apoposition (from apo = away from) was distinguished as a position in which the first carpometacarpal joint is fully abducted and laterally rotated and in which one or both distal joints of the thumb are flexed. Apoposition is commonly used in writing and it has a specific osteoligamentous basis for its stability: (1) a Y-shaped intermetacarpal ligament is attached by two crura to the base of the second metacarpal bone and by a common stem to the first metacarpal. Together with the palmar and dorsal oblique ligaments it becomes taut at abduction and establishes thereby a fixed center for the circumduction. Stability is enhanced as the circumduction takes place in the radial flat part of the joint away from the center; (2) of the two palmar prominences of the head of the first metacarpal bone the radial is the larger. At 25-30 degrees flexion in the metacarpophalangeal joint the prominence fits into an excavation on the base of the proximal phalanx in a manner which together with the ulnar collateral ligament locks the joint against mutual abduction and lateral rotation, and (3) the radial part of the trochlea of the interphalangeal joint is larger than the ulnar and secures, together with the ulnar collateral ligament, the joint against a radial luxation. Apoposition does not require activity of the thumb muscles; it is brought about by applying an external force to the ulnar side of the thumb and it is checked by ligaments and the shape of the joints.     

Purification and properties of human N-acetylgalactosamine-6-sulfate sulfatase

1. Human N-acetylgalactosamine-6-sulfate sulfatase (EC 3.1.6.-) from human placenta has been purified more than 3000-fold by gel filtration, ion-exchange and substrate affinity chromatography. The enzyme has a molecular weight of 90 000 by gel filtration chromatography and 85 000 by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Enzyme purified from cultured human skin fibroblasts has similar properties. 2. The tritium-labeled chrondroitin 6-sulfate trisaccharide N-acetylgalactosamine 6-sulfate-(beta, 1-4)-glucuronic acid-(beta, 1-3(-N-acetyl[1-3H]galactosaminitol 6-sulfate as substrate demonstrated a Km of 0.12 mM at pH 4.5. Sulfate was hydrolyzed only from the non-reducing terminal of this disulfated trisaccharide. Hyaluronic acid, dermatan sulfate, chondroitin 4-sulfate, heparin and chondroitin 6-sulfate tetrasaccharide were slightly inhibitory, whereas 6-sulfated pentasaccharides and heptasaccharides were strongly inhibitory. The enzyme dose not hydrolyze sulfate from N-acetylglucosamine 6-sulfate.     

Perception of solar UVB radiation by phytophagous insects: behavioral responses and ecosystem implications

Most of our present knowledge about the impacts of solar UVB radiation on terrestrial ecosystems comes from studies with plants. Recently, the effects of UVB on the growth and survival of consumer species have begun to receive attention, but very little is known about UVB impacts on animal behavior. Here we report that manipulations of the flux of solar UVB received by field-grown soybean crops had large and consistent effects on the density of the thrips (Caliothrips phaseoli, Thysanoptera: Thripidae) populations that invaded the canopies, as well as on the amount of leaf damage caused by the insects. Solar UVB strongly reduced thrips herbivory. Thrips not only preferred leaves from plants that were not exposed to solar UVB over leaves from UVB-exposed plants in laboratory and field choice experiments, but they also appeared to directly sense and avoid exposure to solar UVB. Additional choice experiments showed that soybean leaf consumption by the late-season soybean worm Anticarsia gemmatalis (Lepidoptera: Noctuidae) was much less intense in leaves with even slight symptoms of an early thrips attack than in undamaged leaves. These experiments suggest that phytophagous insects can present direct and indirect behavioral responses to solar UVB. The indirect responses are mediated by changes in the plant host that are induced by UVB and, possibly, by other insects whose behavior is affected by UVB.