Pain, paradox, and value

The author argues that "as soon as one begins to study the understanding and management of pain in science, human medicine, and veterinary medicine, one begins to encounter a variety of apparent paradoxes." He contends that these paradoxes, ten of which he identifies and discusses in this essay, are based on flawed philosophical and valuational assumptions underlying science and medicine. Rollins concludes that, as social morality increasingly has an impact on science, a new ideology will evolve that is more receptive to the moral universe and more capable of a "coherent vision of pain, one which acknowledges that the medical notion of adequacy of anaesthesia is as much a moral as a scientific one."     

Detection and partial purification of two lipases fromCandida rugosa

Summary Two distinct lipases produced byCanadida rugosa were identified and separated by a high resolution anion-exchange column (Mono Q) after an ethanol extraction of the crude lipase. From this Mono Q column, lipase I eluted at 0.05 M NaCl whereas lipase II eluted at 0.15 M NaCl. The less anionic nature of lipase I was also confirmed by native polyacrylamide gel electrophoresis as well as isoelectrophoresis. Both proteins have an apparent molecular weight of 58,000 by SDS-PAGE. The isoelectric points of lipase I and II are 5.6 and 5.8 respectively.     

Single-stranded circular DNA generated from broad host range plasmid R1162 and its derivatives

Extraction of R1162 plasmid DNA with the alkaline lysis method yields considerable amounts of single-stranded circular plasmid DNA. Destabilization of plasmid DNA is stimulated by the R1162 mob region in cis. The formation of single-stranded circular DNA is initiated at a specific site on the plasmid, presumably the origin of transfer (oriT).     

The kinetics of the thermal deactivation of transglutaminase from guinea-pig liver

By incubating native (N) transglutaminase from guinea-pig liver at various temperatures and assaying it at 25 degrees C, two steps in the irreversible deactivation process to the denatured form (D) have been found. The fitting of the data to the equations of two possible models (the two-steps model and the two-isoenzymes model) is only compatible with the first one (N----X----D). It is shown that the structure of the active intermediate, X, depends on the deactivation temperature and on the thermal history of the enzyme. This may mean that transglutaminase exists in a large number of microstates. Surprisingly, the activation energy of deactivation is lower than that of activity (36.6 +/- 3.4 against 47.2 +/- 2.2 kJ.mol-1). By deactivating transglutaminase at a constant temperature (55 degrees C) and assaying it at variable temperatures, the activation energy of the intermediate, (X55), has been determined to be 40.2 +/- 5 kJ.mol-1, of the same order of magnitude as the native form. Among several agents assayed, only Ca2+ had a positive effect on the thermal stability of this enzyme. At 40 degrees C, transglutaminase was quite stable in the presence of Ca2+ (in its absence, the half-life was 65 min) and at 45 degrees C, its thermostability had been considerably increased, the half-life being raised from 47 min to 275 min.     

Nematode parasites of birds of the fauna in Tunisia

330 birds of Tunisia were necropsied; they belong to 73 species among 29 families and 13 orders. We so collect 36 species of nematodes from 9 families. The relative importance of these is variable. The best represented are: Capillariidae (6 species), Spiruridae (6 species), Acuariidae (9 species) and Filariidae (6 species). The parasitism by nematodes is not uniform. Among the 330 birds autopsied only 51 were parasited by nematodes (15.45%) among 25 of the examined birds species (34.2%). Among these 25, sixteen (64%) presented only one species of parasitic nematode, six (24%) arboured two, (8%) three and only one, (partridges) presents six species of nematodes.     

Oligosaccharide synthesis by enzymatic transglycosylation

The mention of trade products or firm names does not imply that they are endorsed or recommended by the U.S.D.A. over other firms or similar products not mentioned.     

Reconstituted skin in culture:a simple method with optimal differentiation

Human skin is a unique organ, which can be reconstituted in vitro and represents an interesting system for studying cell proliferation and differentiation. A simple technique for producing reconstituted skin with optimal epidermal differentiation is described and characterized. A 4-mm punch biopsy of normal human skin is deposited on the epidermal side of mortified de-epidermized human dermis maintained at the air-liquid interface with a metallic support. The culture medium contains insulin, epidermal growth factor (EGF), cholera toxin, hydrocortisone, penicillin/streptomycin and fungizone. A well-differentiated epidermis develops within 15 days. Morphological and ultrastructural studies show a neoepidermis resembling normal skin. Differentiation markers such as involucrin, filaggrin, and various cytokeratins detected with pancytokeratin antibody are present and confirm this resemblance. The keratin profile is comparable to that observed in other skin culture models. A basement-membrane-like structure is reconstituted with hemidesmosomes and anchoring-filament formation. Bullous pemphigoid (BP) antigen is observed at the dermo-epidermal junction after 21 days of culture. Moreover, both dermal substrates and punch biopsies can be kept frozen for long-term storage, with little or no loss of epidermal growth kinetics and morphology. This skin culture technique is rapid, simple, economical and reproducible. Characterization has here shown high-quality epidermal differentiation. Scientists interested in epidermal in vitro studies should take interest in all these advantages.     

Plant regeneration by organogenesis in Vitis rootstock species

A procedure for the regeneration of Vitis rootstocks plantlets by organogenesis from foliar tissues is described. Leaves from mature plants grown in growth chambers or from plantlets grown in tubes were wounded with a scalpel and cultured on a modified Murashige and Skoog liquid medium containing different concentrations of benzyl-aminopurine. The presence of benzyl-aminopurine is required for shoot formation. The age of the source explant, the composition of the culture medium and the culture temperature are important parameters of the regeneration process.Abbreviations BA 6-benzyl-aminopurine - MS Murashige and Skoog medium - MM modified Murashige and Skoog medium