RISK AND MID‐LEVEL MORAL PRINCIPLES

We discuss ethical aspects of risk‐taking with special focus on principlism and mid‐level moral principles. A new distinction between the strength of an obligation and the degree to which it is valid is proposed. We then use this distinction for arguing that, in cases where mid‐level moral principles come into conflict, the moral status of the act under consideration may be indeterminate, in a sense rendered precise in the paper. We apply this thought to issues related to pandemic influenza vaccines. The main conclusion of the paper is that on a principlist approach some acts may be neither right nor wrong (or neither permissible nor impermissible), and we claim that this has important implications for how we ought to make decisions under risk.     

A Cell Culture System for Study of the Development of Toxoplasma gondii Bradyzoites

ABSTRACT. Toxoplasma gondii is a ubiquitous apicomplexan parasite and a major opportunistic pathogen under AIDS-induced conditions, where it causes encephalitis when the bradyzoite (cyst) stage is reactivated. A bradyzoite-specific Mab, 74.1.8, reacting with a 28 kDa antigen, was used to study bradyzoite development in vitro by immuno-electron microscopy and immunofluorescence in human fibroblasts infected with ME49 strain T. gondii . Bradyzoites were detected in tissue culture within 3 days of infection. Free floating cyst-like structures were also identified. Western blotting demonstrated the expression of bradyzoite antigens in these free-floating cysts as well as in the monolayer. Bradyzoite development was increased by using media adjusted to pH 6.8 or 8.2. The addition of γ-interferon at day 3 of culture while decreasing the total number of cysts formed prevented tachyzoite overgrowth and enabled study of in vitro bradyzoites for up to 25 days. The addition of IL-6 increased the number of cysts released into the medium and increased the number of cysts formed at pH 7.2. Confirmation of bradyzoite development in vitro was provided by electron microscopy. It is possible that the induction of an acute phase response in the host cell may be important for bradyzoite differentiation. This system should allow further studies on the effect of various agents on the development of bradyzoites.     

Changes in Soybean Raceme and Petiole Anatomy Induced by 6-Benzylaminopurine

An enlargement of the peduncle and rachis of the terminal racemeand the petiole of the uppermost mainstem leaf was observedin soybean plants [Glycine max (L.) Merr.] treated with thecytokinin, 6-benzylaminopurine (BAP). Histological studies wereperformed to determine the timing and extent of anatomical changesaccompanying BAP treatment. Swelling of treated ‘Tracy-M’peduncles, rachises, and petioles was observed within 4–6d after treatment initiation. A significant increase in totalcross-sectional tissue area was observed at lower and intermediateinternodes of treated rachises after 11 d. Rachis enlargementwas due to increases in both cell size and cell number, particularlyof the vascular tissue. In treated petioles of IX93-100, procambialcells of vascular bundles were the first to respond to the BAPtreatment. These cells differentiated into a vascular cambiumwhich formed secondary xylem and phloem. Soybean, Glycine max (L.) Merr., anatomy, rachis, BAP.     

Soft Rot Erwinia Bacteria in the Atmospheric Bacterial Aerosol

Using a Casella High Volume Airborne Bacteria Sampler, the soft rot coliform bacteria Erwinia carotovora var. carotovora and E. carotovora var. atroseptica were caught from the open air during rainfall in mid to late summer, autumn and early winter, but not in late winter, spring or early summer. They were not found every time it rained, and never when the weather was dry. The bacteria were caught close to potato crops, but there were several occasions when they were found at sites where there were no such crops or at times of year after potato crops had been harvested. The sources of the organisms are uncertain, but those obtained close to potato crops may have originated there. The results are considered to provide further evidence that airborne spread and subsequent deposition of viable bacteria could cause contamination of Erwinia -free potato stocks, and suggest that rainfall is a major generator of the general atmospheric bacterial aerosol.     

The Effect of Sucrose on Primordium Development and on Protein and RNA Levels in Detached Cotyledons of Sinapis alba L.

Cotyledons of Sinapis alba cultured in the light on filter-papermoistened with water initiated root primordia within 2 daysafter detachment. These increased in size and penetrated thebase of the petiole after a further 3 days. Culture in sucrosesolution in the light inhibited root formation mainly by affectingthe extension phase when many primordia regressed resultingin a decline in the numbers of primordia per petiole. When cotyledonswere cultured in the dark no primordia were initiated in water,but sucrose promoted root formation. Levels of RNA rose to a peak value in the terminal petiole segmentat a time when primordia were being initiated in this region,protein reached a peak 2 days later. This pattern was much lessevident in the subterminal segments. It did not occur at allin cotyledons cultured in sucrose in the light where a smallinitial increase in RNA and protein was followed by a rapiddecline. The level of RNA and protein in the terminal segmentin light-cultured cotyledons in water was related to the numberof light periods given following detachment as was the percentageof cotyledons which formed roots. The effect of sucrose on RNAand protein content was less marked when cotyledons were transferredfrom sucrose to water instead of being maintained in sucrosethroughout. Sucrose clearly modifies the biochemical and structural changestaking place at the petiole base having particularly inhibitoryeffects on the extension phase of the primordia. The evidenceindicates that sucrose could be causing premature ageing ofcells forming the primordia.     

Changes in the composition of understorey vegetation after harvesting eucalypts for sawlogs and pulpwood in East Gippsland

Cover and abundance of all understorey vascular plant species were studied on permanent plots on two areas (Maramingo and Reedy Creek) in the foothill forests of East Gippsland, eastern Victoria. The areas were harvested for sawlogs and pulpwood in 1976, and parts were burned to assist regeneration. Plots were assessed before harvesting and at intervals until 1980. Changes in total species composition were minimal, although there were many positive and negative changes in crown cover and abundance of individual species. Total cover of understorey vegetation was reduced initially but recovered well on both areas. By 1980, cover at Maramingo was slightly greater than the low levels before harvesting. Some species there were favoured by burning while others were not. At Reedy Creek the original dense understorey had not regenerated fully by 1980. Snig tracks had revegetated to 60% of original average cover but log landings were slower to revegetate. Introduced species were initially a very minor component of the vegetation on both areas: they remained so at Reedy Creek (confined mainly to tracks) but at Maramingo three species proliferated along with other small herbaceous plants.     

COMPARISON OF SOURNESS OF ORGANIC ACID ANIONS AT EQUAL pH AND EQUAL TITRATABLE ACIDITY

The sourness of six organic acids was compared by pair tests in binary acid solutions of equal pH and equal potential hydrogen ion concentration. Monoprotic lactic acid was more sour than three of the four acids against which it was tasted, while triprotic citric acid was less sour than the four other acids against which it was compared. Of the diprotic acid pairs which were evaluated, only one significant difference in sourness was observed; succinic acid was more sour than malic acid. No relationship between buffer capacity or hydrophobicity and intensity of sourness was observed.