Anabolic and catabolic responses of human articular chondrocytes to varying oxygen percentages

Introduction  

Oxygen is a critical parameter proposed to modulate the functions of chondrocytes ex-vivo as well as in damaged joints. This article investigates the effect of low (more physiological) oxygen percentage on the biosynthetic and catabolic activity of human articular chondrocytes (HAC) at different phases of in vitro culture.     

Mycotoxin formation in moist wheat under controlled temperatures

One-kilogram parcels of wheat with 20.5% moisture content were maintained at 15° and 22 °C for 10 weeks to study quality changes. Temperature, moisture, oxygen and carbon dioxide levels, microfloral incidence and abundance, seed germination, fat acidity values, aflatoxins, sterigmatocystin, ochratoxin A, penicillic acid, citrinin and zearalenone were monitored. By two weeks, trace levels of ochratoxin had formed at both temperatures. By 10 weeks, the wheat contained at least three times more ochratoxin A at 22 °C than at 15 °C. Strains of Penicillium verrucosum var. cyclopium were associated with ochratoxin A production. No other mycotoxins were detected. The effect of temperature was significant for all variables (greater effect at 22 °C) except A. glaucus gr. and Penicillium (P<.01). The effect of time was significant for all variables except bacteria (P<.01). The shape of the response was fully characterized by the linear and quadratic terms, except for % moisture which was linear only, and for bacteria for which time was not significant. The interaction between time and temperature was significant (P<.01) for total fungal propagule count, % moisture, and Aspergillus versicolor, indicative of the steeper rise in slope for 22 °C.     

Developments in the scientific understanding of osteoarthritis

Osteoarthritis is often a progressive and disabling disease, which occurs in the setting of a variety of risk factors – such as advancing age, obesity, and trauma – that conspire to incite a cascade of pathophysiologic events within joint tissues. An important emerging theme in osteoarthritis is a broadening of focus from a disease of cartilage to one of the 'whole joint'. The synovium, bone, and cartilage are each involved in pathologic processes that lead to progressive joint degeneration. Additional themes that have emerged over the past decade are novel mechanisms of cartilage degradation and repair, the relationship between biomechanics and biochemical pathways, the importance of inflammation, and the role played by genetics. In this review we summarize current scientific understanding of osteoarthritis and examine the pathobiologic mechanisms that contribute to progressive disease.     

Ethanol-Induced Effects on Sting Extension Response and Punishment Learning in the Western Honey Bee (Apis mellifera)

Acute ethanol administration is associated with sedation and analgesia as well as behavioral disinhibition and memory loss but the mechanisms underlying these effects remain to be elucidated. During the past decade, insects have emerged as important model systems to understand the neural and genetic bases of alcohol effects. However, novel assays to assess ethanol''s effects on complex behaviors in social or isolated contexts are necessary. Here we used the honey bee as an especially relevant model system since bees are typically exposed to ethanol in nature when collecting standing nectar crop of flowers, and there is recent evidence for independent biological significance of this exposure for social behavior. Bee''s inhibitory control of the sting extension response (SER) and a conditioned-place aversion assay were used to study ethanol effects on analgesia, behavioral disinhibition, and associative learning. Our findings indicate that although ethanol, in a dose-dependent manner, increases SER thresholds (analgesic effects), it disrupts the ability of honey bees to inhibit SER and to associate aversive stimuli with their environment. These results suggest that ethanol''s effects on analgesia, behavioral disinhibition and associative learning are common across vertebrates and invertebrates. These results add to the use of honey bees as an ethanol model to understand ethanol''s effects on complex, socially relevant behaviors.     

ELECTROKINETIC PHENOMENA. III : THE "ISOELECTRIC POINT" OF NORMAL AND SENSITIZED MAMMALIAN ERYTHROCYTES

A survey of the published electrophoretic mobilities of certain mammalian red cells reveals that the isoelectric points accorded to these cells are the result of equilibria incidental to red cell destruction. The electrophoretic mobilities of normal washed sheep and human cells have now been studied in 0.85 per cent NaCl solutions from about pH 3.6 to 7.4. All measurements were made within 2 minutes of the preparation of the suspension of red cells. In no case was reversal of sign of charge observed under these conditions. Reversal of sign of charge occurred only after sufficient time had elapsed to permit sufficient adsorption of the products of red cell destruction. There is little change in mobility as the pH of the medium is decreased. Reversal of sign of charge does occur in the presence of normal and immune (anti-sheep) rabbit sera. The isoelectric point determined under these conditions does not appear to be connected specifically with the immune body but is perhaps associated with phenomena incidental to red cell destruction and the presence of serum. The characteristic lowering of mobility by amboceptor occurs, however, from pH 4.0 to pH 7.4. The curves of mobility plotted against pH for normal and for immune sera support the viewpoint that the identity of the isoelectric points for normal and sensitized sheep cells is not primarily concerned with the immune reaction. It is most unlikely that an "albumin" or a "globulin" surface covers red cells with a complete protein film. Although serum protein reacts with red cells in acid solutions, this is not demonstrable for gelatin. The lowering of mobility usually ascribed to anti-sheep rabbit serum may also occur, but to a lesser degree, in normal rabbit serum. This diminution of mobility is not, in the first place, associated with sensitization to hemolysis induced by complement. This supports the view that only a very small part of the red cell surface need be changed in order to obtain complete hemolysis in the presence of complement.