Special report of the Massachusetts weight‐of‐evidence workgroup A weight‐of‐evidence approach for evaluating ecological risks

Weight‐of‐evidence is the process by which multiple measurement endpoints are related to an assessment endpoint to evaluate whether significant risk of harm is posed to the environment. In this paper, a methodology is offered for reconciling or balancing multiple lines of evidence pertaining to an assessment endpoint. Weight‐of‐evidence is reflected in three characteristics of measurement endpoints: (a) the weight assigned to each measurement endpoint; (b) the magnitude of response observed in the measurement endpoint; and (c) the concurrence among outcomes of multiple measurement endpoints. First, weights are assigned to measurement endpoints based on attributes related to: (a) strength of association between assessment and measurement endpoints; (b) data quality; and (c) study design and execution. Second, the magnitude of response in the measurement endpoint is evaluated with respect to whether the measurement endpoint indicates the presence or absence of harm; as well as the magnitude. Third, concurrence among measurement endpoints is evaluated by plotting the findings of the two preceding steps on a matrix for each measurement endpoint evaluated. The matrix allows easy visual examination of agreements or divergences among measurement endpoints, facilitating interpretation of the collection of measurement endpoints with respect to the assessment endpoint. A qualitative adaptation of the weight‐of‐evidence approach is also presented.     

Enhancement of secondary metabolite production using the antibiotic gradient-plate technique.

We have used the antibiotic gradient-plate technique to generate antifungal producing Actinomadura strains that synthesize enhanced quantities of component 3A of a macrocyclic lactam antifungal compound Sch 38516. Seventy-nine colonies were selected from a mixture of rifampicin and spectinomycin gradient plates. The two fermentation extracts described produced an enhanced 3A component (identified with silica gel TLC, HPLC, and bioautography) when compared to the parent culture isolate extracts (no antibiotic selection).     

Variations of Phenoloxidase Activities as a Consequence of Stresses that Induce Resistance to Fusarium Wilt of Tomato

The variations over 7–8 day of peroxidase (PO) and polyphenoloxidase (PPO) activity have been investigated in tomato plants the roots of which had been subjected to stresses (heat, chloroform and a non-pathogenic form of Fusarium oxysporum) that induce resistance to Fusarium oxysporum f. sp. lycopersici. All treatments induced increase of PO and PPO activity that reached a maximum 3 days after the treatments in leaves, 4 days in stem and roots and were higher in leaves than in other parts. Activity decreased to levels for the control plants after 8 days. Inoculation with Fusarium oxysporum f. sp. lycopersici further stimulated PO and PPO activity in all treated plants over that caused by the treatments alone. Again, activity of treated plants was lower than in controls 7 days after inoculation. It is concluded that 1. increased PO and PPO activity in tomato is a systemic response to cellular injury caused in the root by heat, chloroform and non-pathogenic Fusarium oxysporum, 2. these treatments do no prevent the pathogen from interacting with the plants and inducing further enzyme increase, 3. treated plants react more strongly to the challenge inoculation than untreated plants.     

Effect of Chemical Thymectomy on Skin Homografts: A Preliminary Report

In an attempt to combine the results obtained by Miller (mice thymectomized at birth accepted homograft at six weeks of age) and those obtained by Selye (selective calcification of the cortex of the thymus with calciphylaxis), calcification of the thymus was produced by the combined injection of dihydrotachysterol and triamcinolone, in non-inbred Sprague-Dawley and hooded, eight-week-old rats. Six days after the beginning of treatment, full-thickness skin homografts were performed on the rats.Homografts exchanged between two rats with complete calcification of the thymus cortex were accepted for an extended period of time, which in the oldest rats at the time of writing was seven months. Homografts exchanged between rats with incomplete calcification of the thymus resulted in a prolonged homograft survival with final rejection within a period of three weeks. Homografts exchanged between rats that were not treated, surgically thymectomized at the same age as the treated animals, or treated with only one of the two substances used for thymus calcification, resulted in rejection in the average time of eight days.     

Mutagenicity of selected aniline derivatives to Salmonella following plant activation and mammalian hepatic activation

We compared several phenylenediamines (4-nitro-o-phenylenediamine, NOP; 2-nitro-p-phenylenediamine, NPD; o-phenylenediamine, OPD; p-phenylenediamine, PPD; m-phenylenediamine, MPD) and aniline (ANL) for mutagenicity to Salmonella directly and following activation by plant and mammalian hepatic S9 using plate incorporation and preincubation protocols. In addition, we assayed each chemical for activation by intact plant cells using the plant cell/microbe coincubation protocol. At the concentrations tested, NOP, NPD, OPD, MPD and ANL were active in one or more assays. NPD, OPD and MPD were activated by mammalian hepatic S9 in one or more assay and each was activated by plant S9 or intact plant cells. ANL was mutagenic only in the presence of plant S9. PPD was not active under any of the test conditions.     

Human pluripotent stem cells identify molecular targets of trisomy 12 in chronic lymphocytic leukemia patients

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