Quantification of 8-iso-prostaglandin-F(2alpha) and 2,3-dinor-8-iso-prostaglandin-F(2alpha) in human urine using liquid chromatography-tandem mass spectrometry

Quantification of 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) has been suggested to be a reliable indicator of lipid peroxidation that may be related to in vivo free radical generation, oxidative damage, and antioxidant deficiency. We have developed a LC-MS/MS method to quantify 8-iso- PGF(2alpha) and its dinor metabolite, 2,3-dinor-8-iso-prostaglandin F(2alpha) (2,3-dinor-8-iso-PGF(2alpha)), in human urine samples. After an initial purification step using an automated C18 solid phase extraction procedure, the urine sample was injected directly into a liquid chromatography (LC) system and detected with tandem mass spectrometry. The detection limit of the assay was 9 pg for 8-iso-PGF(2alpha) and 3 pg for 2,3-dinor-8-iso-PGF(2alpha) with both inter- and intraday variations of less than 12%. The inaccuracies were less than 3% for both analytes at three different levels. The urinary excretion rate of 2,3-dinor-8-iso-PGF(2alpha) was higher than that of 8-iso-PGF(2alpha), and changed in proportion to the parent compound (R = 0.70, n = 60). Values obtained with this method showed good linear correlation to duplicate 8-iso-PGF(2alpha) measurements performed with GCMS (R = 0.97, n = 15). The mean excretion rates of 8-iso-PGF(2alpha) and 2,3-dinor-8-iso-PGF(2alpha) were significantly higher in smokers than in nonsmokers (0.53 +/- 0.37 vs. 0.25 +/- 0.15 microg/g creatinine, p = 0.002 for 8-iso-PGF(2alpha) and 8.9 +/- 3.8 vs. 4.6 +/- 2.6 microg/g creatinine, p = 0.003 for 2,3-dinor-8-iso-PGF(2alpha), respectively). The excellent accuracy, reproducibility, and high throughput of this method should permit it to be used in large clinical studies and standard clinical laboratories.     

Determining the origin and age of the Westland beech (Nothofagus) gap, New Zealand, using fungus beetle genetics

The formation and maintenance of the Nothofagus beech gap in the South Island, New Zealand, has been the focus of biogeographical debate since the 1920s. We examine the historical process of gap formation by investigating the population genetics of fungus beetles: Brachynopus scutellaris (Staphylinidae) inhabits logs and is absent from the beech gap, and Hisparonia hystrix (Nitidulidae) is contiguous through the gap and is found commonly on sooty mould growing on several plant species. Both species show distinctive northern and southern haplotype distributions while H. hystrix recolonized the gap as shown by definitive mixing. B. scutellaris shows two major haplotype clades with strong geographical concordance, and unlike H. hystrix, has clearly defined lineages that can be partitioned for molecular dating. Based on coalescence dating methods, disjunct lineages of B. scutellaris indicate that the gap was formed less than 200 000 years ago. Phylogenetic imprints from both species reveal similar patterns of population divergence corresponding to recent glacial cycles, favouring a glacial explanation for the origin of the gap. Post-gap colonization by H. hystrix may have been facilitated by the spread of Leptospermum scoparium host trees to the area, and they may be better at dispersing than B. scutellaris which may be constrained by fungal host and/or microhabitat. The gap-excluded species B. scutellaris is found in both beech and podocarp-broadleaf forests flanking the Westland gap and its absence in the gap may be related to incomplete recolonization following glacial retreat. We also discuss species status and an ancient polymorphism within B. scutellaris .     

A design criterion for symmetric model discrimination based on flexible nominal sets

Experimental design applications for discriminating between models have been hampered by the assumption to know beforehand which model is the true one, which is counter to the very aim of the experiment. Previous approaches to alleviate this requirement were either symmetrizations of asymmetric techniques, or Bayesian, minimax, and sequential approaches. Here we present a genuinely symmetric criterion based on a linearized distance between mean-value surfaces and the newly introduced tool of flexible nominal sets. We demonstrate the computational efficiency of the approach using the proposed criterion and provide a Monte-Carlo evaluation of its discrimination performance on the basis of the likelihood ratio. An application for a pair of competing models in enzyme kinetics is given.     

Effect of colony morphology variation of <Emphasis Type="Italic">Burkholderia pseudomallei</Emphasis> on intracellular survival and resistance to antimicrobial environments in human macrophages in vitro

Background  

Primary diagnostic cultures from patients with melioidosis demonstrate variation in colony morphology of the causative organism, Burkholderia pseudomallei. Variable morphology is associated with changes in the expression of a range of putative virulence factors. This study investigated the effect of B. pseudomallei colony variation on survival in the human macrophage cell line U937 and under laboratory conditions simulating conditions within the macrophage milieu. Isogenic colony morphology types II and III were generated from 5 parental type I B. pseudomallei isolates using nutritional limitation. Survival of types II and III were compared with type I for all assays.     

Variation in heat shock proteins within tropical and desert species of poeciliid fishes

The 70-kilodalton heat shock protein (hsp70) family of molecular chaperones, which contains both stress-inducible and normally abundant constitutive members, is highly conserved across distantly related taxa. Analysis of this protein family in individuals from an outbred population of tropical topminnows, Poeciliopsis gracilis, showed that while constitutive hsp70 family members showed no variation in protein isoforms, inducibly synthesized hsp70 was polymorphic. Several species of Poeciliopsis adapted to desert environments exhibited lower levels of inducible hsp70 polymorphism than the tropical species, but constitutive forms were identical to those in P. gracilis, as they were in the confamilial species Gambusia affinis. These differences suggest that inducible and constitutive members of this family are under different evolutionary constraints and may indicate differences in their function within the cell. Also, northern desert species of Poeciliopsis synthesize a subset of the inducible hsp70 isoforms seen in tropical species. This distribution supports the theory that ancestral tropical fish migrated northward and colonized desert streams; the subsequent decrease in variation of inducible hsp70 may have been due to genetic drift or a consequence of adaptation to the desert environment. Higher levels of variability were found when the 30- kilodalton heat shock protein (hsp30) family was analyzed within different strains of two desert species of Poeciliopsis and also in wild-caught individuals of Gambusia affinis. In both cases the distribution of hsp30 isoform diversity was similar to that seen previously with allozyme polymorphisms.      

The cover of living and dead corals from airborne remote sensing

Trends in coral cover are widely used to indicate the health of coral reefs but are costly to obtain from field survey over large areas. In situ studies of reflected spectra at the coral surface show that living and recently dead colonies can be distinguished. Here, we investigate whether such spectral differences can be detected using an airborne remote sensing instrument. The Compact Airborne Spectrographic Imager (Itres Research Ltd, Canada) was flown in two configurations: 10 spectral bands with 1-m² pixels and 6 spectral bands with 0.25-m² pixels. First, we show that an instrument with 10 spectral bands possesses adequate spectral resolution to distinguish living Porites, living Pocillopora spp., partially dead Porites, recently dead Porites (total colony mortality within 6 months), old dead (>6 months) Porites, Halimeda spp., and coralline red algae when there is no water column to confuse spectra. All substrata were distinguished using fourth-order spectral derivatives around 538 nm and 562 nm. Then, at a shallow site (Tivaru) at Rangiroa Atoll, Tuamotu Archipelago (French Polynesia), we show that live and dead coral can be distinguished from the air to a depth of at least 4 m using first- and fourth-order spectral derivatives between 562–580 nm. However, partially dead and recently dead Porites colonies could not be distinguished from an airborne platform. Spectral differences among substrata are then exploited to predict the cover of reef substrata in ten 25-m² plots at nearby Motu Nuhi (max depth 8 m). The actual cover in these plots was determined in situ using quadrats with a 0.01-m² grid. Considerable disparity occurred between field and image-based measures of substrate cover within individual 25-m² quadrats. At this small scale, disparity, measured as the absolute difference in cover between field and remote-sensing methods, reached 25% in some substrata but was always less than 10% for living coral (99% of which consisted of Porites spp.). At the scale of the reef (all ten 25-m² quadrats), however, disparities in percent cover between imagery and field data were less than 10% for all substrata and extremely low for some classes (e.g. <3% for living Porites, recently dead Porites and Halimeda). The least accurately estimated substrata were sand and coralline red algae, which were overestimated by absolute values 7.9% and 6.6%, respectively. The precision of sampling was similar for field and remote-sensing methods: field methods required 19 plots to detect a 10% difference in coral cover among three reefs with a statistical power of 95%. Remote-sensing methods required 21 plots. However, it took 1 h to acquire imagery over 92,500 m² of reef, which represents 3,700 plots of 25 m² each, compared with 3 days to survey 10 such plots underwater. There were no significant differences in accuracy between 1-m² and 0.25-m² image resolutions, suggesting that the advantage of using smaller pixels is offset by reduced spectral information and an increase in noise (noise was observed to be 1.6–1.8 times greater in 0.25-m² pixels). We show that airborne remote sensing can be used to monitor coral and algal cover over large areas, providing that water is shallow and clear, and that brown fleshy macroalgae are scarce, that depth is known independently (e.g. from sonar survey).