18-Substituted steroids. Part 15. 6 beta-Hydroxylation of aldosterone by liver

6 beta-Hydroxyaldosterone and 6 beta-hydroxy-17-isoaldosterone, characterized by high-field NMR studies, are among the major polar metabolites formed from aldosterone by incubation with rat liver slices or microsomal fraction. It is uncertain at present whether the 17-iso product results from an enzymatic or a chemical inversion of configuration. Periodate degradation of the 6 beta-hydroxyaldosterone gave 6 beta-hydroxyaldosterone gamma-lactone, identical with a synthetic sample.     

Breast-feeding and respiratory syncytial virus infection.

The pattern of breast-feeding in 127 infants admitted to hospital with respiratory syncytial virus infection was compared with that in 503 age-matched controls. Thirty per cent of children with infection had been breast-fed compared with 49% of controls. The approximate relative risk of being admitted to hospital with respiratory syncytial virus infection if not breast-fed was 2.2. Several other factors were also considered, including an assessment of maternal care and home environment; the mother''s age, marital state, and smoking habits; the number of siblings; and gestation. Adverse factors were all associated with an increased risk of admission with infection, but breast-feeding still appeared to provide protection after controlling for these other factors in turn. These findings provide further support for encouraging mothers to breast-feed their infants and should prompt further studies into the immune status of mothers and into the nature of the protective factors in their breast milk.     

Revisiting the use of Iprodione and Trichoderma in the integrated management of onion white rot

The biocontrol properties of Trichoderma species are well documented, but their effectiveness in antagonism of the problematic Sclerotium cepivorum, the causal agent of white rot in Allium species, appears limited with reports of significant control only relating to deliberately-mutated strains of Trichoderma. Our previous studies have indicated the possibility of using selected naturally-occurring strains of the antagonist in the suppression of other diseases; now in vitro and controlled environment in vivo studies have indicated that a degree of control of Onion White Rot is possible, and that the selected antagonist strains can be used in integrated treatments with Iprodione to good effect. The possible value of such treatments is considered in light of other approaches to the suppression of this continuing problem.     

Long-term decline of a winter-resident bird community in Puerto Rico

Despite concern expressed two decades ago, there has been little recent discussion about continuing declines of migrant bird populations. Monitoring efforts have been focused almost exclusively on the breeding grounds. We describe the long-term decline of a winter-resident bird population in Guánica Commonwealth Forest, Puerto Rico, one of the last remaining tracts of high-quality tropical dry forests in the Caribbean. The winter bird community has exhibited dramatic declines, with constant-effort mist netting now capturing about one-third as many birds as it did 20 years ago. Population estimates for the three most common species have declined dramatically, even though survival rates have remained constant, and other species are now virtually absent from a site where they once were fairly common. Although explanations for these declines are speculative, particularly because they involve multiple species, we argue that the strength and duration of these declines in well-preserved dry forest within a biosphere reserve should stimulate renewed discussion of migrant population trends and comparison with other recent monitoring activities.     

Assessing factors associated with changes in the numbers of birds visiting gardens in winter: Are predators partly to blame?

The factors governing the recent declines observed in many songbirds have received much research interest, in particular whether increases of avian predators have had a negative effect on any of their prey species. In addition, further discussion has centered on whether or not the choice of model formulation has an effect on model inference. The study goal was to evaluate changes in the number of 10 songbird species in relation to a suite of environmental covariates, testing for any evidence in support of a predator effect using multiple model formulations to check for consistency in the results. We compare two different approaches to the analysis of long‐term garden bird monitoring data. The first approach models change in the prey species between 1970 and 2005 as a function of environmental covariates, including the abundance of an avian predator, while the second uses a change–change approach. Significant negative relationships were found between Eurasian Sparrowhawk Accipiter nisus and three of the 10 species analyzed, namely house Sparrow Passer domesticus, starling Sturnus vulgaris, and blue tit Cyanistes caeruleus. The results were consistent under both modeling approaches. It is not clear if this is a direct negative impact on the overall populations of these species or a behavioral response of the prey species to avoid feeding stations frequented by Sparrowhawks (which may in turn have population consequences, by reducing available resources). The species showing evidence of negative effects of Sparrowhawks were three of the four species most at risk to Sparrowhawk predation according to their prevalence in the predator's diet. The associations could be causal in nature, although in practical terms the reduction in the rate of change in numbers visiting gardens accredited to Sparrowhawks is relatively small, and so unlikely to be the main driver of observed population declines.     

Inhibition of cobalamin-dependent methionine synthase by substituted benzo-fused heterocycles

The cobalamin-dependent cytosolic enzyme, methionine synthase (EC.2.1.1.13), catalyzes the remethylation of homocysteine to methionine using 5-methyltetrahydrofolate as the methyl donor. The products of this remethylation--methionine and tetrahydrofolate--participate in the active methionine and folate pathways. Impaired methionine synthase activity has been implicated in the pathogenesis of anaemias, cancer and neurological disorders. Although the need for potent and specific inhibitors of methionine synthase has been recognized, there is a lack of such agents. In this study, we designed, synthesized and evaluated the inhibitory activity of a series of substituted benzimidazoles and small benzothiadiazoles. Kinetic analysis revealed that the benzimidazoles act as competitive inhibitors of the rat liver methionine synthase, whilst the most active benzothiadiazole (IC(50) = 80 microm) exhibited characteristics of uncompetitive inhibition. A model of the methyltetrahydrofolate-binding site of the rat liver methionine synthase was constructed; docking experiments were designed to elucidate, in greater detail, the binding mode and reveal structural requirements for the design of inhibitors of methionine synthase. Our results indicate that the potency of the tested compounds is related to a planar region of the inhibitor that can be positioned in the centre of the active site, the presence of a nitro functional group and two or three probable hydrogen-bonding interactions.     

A web server to locate periodicities in a sequence

Summary : FT is a tool written in C++, which implements the Fourier analysis method to locate periodicities in aminoacid or DNA sequences. It is provided for free public use on a WWW server with a Java interface. Availability : The server address is http://o2.db. uoa.gr/FT Contact : shamodr@atlas.uoa.gr