Mathematical models of diffusion-limited gas bubble dynamics in tissue

Mathematical models of bubble evolution in tissue have recentlybeen incorporated into risk functions for predicting the incidence ofdecompression sickness (DCS) in human subjects after diving and/or flying exposures. Bubble dynamics models suitable forthese applications assume the bubble to be either contained in anunstirred tissue (two-region model) or surrounded by a boundary layerwithin a well-stirred tissue (three-region model). The contrastingpremises regarding the bubble-tissue system lead to differentexpressions for bubble dynamics described in terms of ordinarydifferential equations. However, the expressions are shown to bestructurally similar with differences only in the definitions ofcertain parameters that can be transformed to make the modelsequivalent at large tissue volumes. It is also shown that thetwo-region model is applicable only to bubble evolution in tissues ofinfinite extent and cannot be readily applied to bubble evolution infinite tissue volumes to simulate how such evolution is influenced byinteractions among multiple bubbles in a given tissue. Two-regionmodels that are incorrectly applied in such cases yield results thatmay be reinterpreted in terms of their three-region model equivalents but only if the parameters in the two-region model transform into consistent values in the three-region model. When such transforms yieldinconsistent parameter values for the three-region model, results maybe qualitatively correct but are in substantial quantitative error.Obviation of these errors through appropriate use of the differentmodels may improve performance of probabilistic models of DCSoccurrence that express DCS risk in terms of simulated in vivo gas andbubble dynamics.     

Fishers' knowledge and seahorse conservation in Brazil

From a conservationist perspective, seahorses are threatened fishes. Concomitantly, from a socioeconomic perspective, they represent a source of income to many fishing communities in developing countries. An integration between these two views requires, among other things, the recognition that seahorse fishers have knowledge and abilities that can assist the implementation of conservation strategies and of management plans for seahorses and their habitats. This paper documents the knowledge held by Brazilian fishers on the biology and ecology of the longsnout seahorse Hippocampus reidi. Its aims were to explore collaborative approaches to seahorse conservation and management in Brazil; to assess fishers' perception of seahorse biology and ecology, in the context evaluating potential management options; to increase fishers' involvement with seahorse conservation in Brazil. Data were obtained through questionnaires and interviews made during field surveys conducted in fishing villages located in the States of Piauí, Ceará, Paraíba, Maranhão, Pernambuco and Pará. We consider the following aspects as positive for the conservation of seahorses and their habitats in Brazil: fishers were willing to dialogue with researchers; although captures and/or trade of brooding seahorses occurred, most interviewees recognized the importance of reproduction to the maintenance of seahorses in the wild (and therefore of their source of income), and expressed concern over population declines; fishers associated the presence of a ventral pouch with reproduction in seahorses (regardless of them knowing which sex bears the pouch), and this may facilitate the construction of collaborative management options designed to eliminate captures of brooding specimens; fishers recognized microhabitats of importance to the maintenance of seahorse wild populations; fishers who kept seahorses in captivity tended to recognize the condtions as poor, and as being a cause of seahorse mortality.     

Science – A life fully lived: Joe Sodroski wins the 2006 Retrovirology Prize

The 2006 M Jeang Retrovirology Prize for HIV research has been awarded to Dr Joe Sodroski     

Elicitation of galanthamine production by leucojum aestivum shoots grown in temporary immersion system

The influence of different elicitors (copper sulfate, silver nitrate, salicylic acid and methyl jasmonate), on both the growth and alkaloid production of Leucojum aestivum shoots grown in a temporary immersion system was studied. Seven Amaryllidaceae alkaloids and three protoalkaloids were quantitatively determined by GC‐MS analysis in leaves and bulblets, separately. Methyl jasmonate was found to significantly improve the production of galanthamine (GAL) in both leaves and bulblets. The content of GAL released to the liquid nutrient medium was also measured. The release of GAL into the liquid medium took place mainly in the first 2 weeks determined by harvesting the liquid nutrient medium after 2 weeks and measuring the GAL content (1st subculturing step). © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29: 311–318, 2013     

Microassay for ammonium by determination of ammonia nitrogen in a nitrogen analyzer

The method described comprises the transformation of ammonium into ammonia, the rapid and gentle liberation of the ammonia followed by the measurement of the nitrogen in a Dohrmann nitrogen analyzer. Untreated biological samples (1-50 microliters) were pipetted onto magnesium oxide tablets at 130 degrees C and the ammonia liberated was transferred by a continuous stream of nitrogen carrier gas into the nitrogen analyzer. There the ammonia was determined by oxidative pyrolysis and subsequent chemiluminescence measurement of the excited NO2. The result could be read in nanograms ammonia nitrogen within 6.5 min. Apart from volatile amines, which are usually negligible in biological samples, the method was specific for ammonia because under the given conditions of volatilization the labile groups of glutamine and asparagine did not interfere. The assay was sensitive in the range of 1.5-150 nmol ammonia and suitable for the routine analysis of small samples.