Comprehensive analysis by liquid chromatography Q-Orbitrap mass spectrometry: Fast screening of peptides and organic molecules.

The number of substances nominally listed in the prohibited list of the World Anti-Doping Agency increases each year. Moreover, many of these substances do not have a single analytical target and must be monitored through different metabolites, artifacts, degradation products, or biomarkers. A new analytical method was developed and validated for the simultaneous analysis of peptides and organic molecules using a single sample preparation and LC-Q-HRMS detection. The simultaneous analysis of 450 target molecules was performed after cleanup on a mixed-mode solid-phase extraction cartridge, combined with untreated urine. The cleanup solvent and reconstitution solvent were the most important parameters for achieving a comprehensive sample preparation approach. A fast chromatographic run based on a multistep gradient was optimized under different flows; the detection of all substances without isomeric coelution was achieved in 11 minutes, and the chromatographic resolution was considered a critical parameter, even in high-resolution mass spectrometry detection. The mass spectrometer was set to operate by switching between positive and negative ionization mode for FULL-MS, all-ion fragmentation, and FULL-MS/MS2 . The suitable parameters for the curved linear trap (c-trap) conditions were determined and found to be the most important factors for the development of the method. Only FULL-MS/MS2 enables the detection of steroids and peptides at concentrations lower than the minimum required performance levels set by World Anti-Doping Agency (1 ng mL-1 ). The combination of the maximum injection time of the ions into the c-trap, multiplexing experiments, and loop count under optimized conditions enabled the method to be applied to over 10 000 samples in only 2 months during the 2016 Rio Summer Olympic and Paralympic Games. The procedure details all aspects, from sample preparation to mass spectrometry detection. FULL-MS data acquisition is performed in positive and negative ion mode simultaneously and can be applied to untargeted approaches.

An allometric approach to quantify the extinction vulnerability of birds and mammals.

Methods to quantify the vulnerability of species to extinction are typically limited by the availability of species-specific input data pertaining to life-history characteristics and population dynamics. This lack of data hampers global biodiversity assessments and conservation planning. Here, we developed a new framework that systematically quantifies extinction risk based on allometric relationships between various wildlife demographic parameters and body size. These allometric relationships have a solid theoretical and ecological foundation. Extinction risk indicators included are (1) the probability of extinction, (2) the mean time to extinction, and (3) the critical patch size. We applied our framework to assess the global extinction vulnerability of terrestrial carnivorous and non-carnivorous birds and mammals. Irrespective of the indicator used, large-bodied species were found to be more vulnerable to extinction than their smaller counterparts. The patterns with body size were confirmed for all species groups by a comparison with IUCN data on the proportion of extant threatened species: the models correctly predicted a multimodal distribution with body size for carnivorous birds and a monotonic distribution for mammals and non-carnivorous birds. Carnivorous mammals were found to have higher extinction risks than non-carnivores, while birds were more prone to extinction than mammals. These results are explained by the allometric relationships, predicting the vulnerable species groups to have lower intrinsic population growth rates, smaller population sizes, lower carrying capacities, or larger dispersal distances, which, in turn, increase the importance of losses due to environmental stochastic effects and dispersal activities. Our study is the first to integrate population viability analysis and allometry into a novel, process-based framework that is able to quantify extinction risk of a large number of species without requiring data-intensive, species-specific information. The framework facilitates the estimation of extinction vulnerabilities of data-deficient species. It may be applied to forecast extinction vulnerability in response to a changing environment, by incorporating quantitative relationships between wildlife demographic parameters and environmental drivers like habitat alteration, climate change, or hunting.

Development and validation of a ultra high performance liquid chromatography-tandem mass spectrometric method for the direct detection of formoterol in human urine.

Formoterol is a long acting ß(2)-agonist and has proven to be a very effective bronchodilating agent. Hence it is frequently applied therapeutically for the treatment of asthma. Because ß(2)-agonists might be misused in sports for the stimulatory effects and for growth-promoting action their use is restricted. Since January 2012, formoterol is prohibited in urinary concentrations higher than 30 ng/mL. The objective of this study was to develop and validate a simple and robust ultra high performance liquid chromatographic-tandem mass spectrometric (UHPLC-MS/MS) method for the direct quantification of formoterol in urine. Sample preparation was limited to an enzymatic hydrolysis step after which 2 µL was injected in the chromatographic system. Chromatography was performed on a C(8)-column using gradient conditions. The mobile phase consisted of water/methanol (H(2)O/MeOH) both containing 0.1% acetic acid (HOAc) and 1mM ammonium acetate (NH(4)OAc). Calibration curve were constructed between 15 and 60 ng/mL. Validation data showed bias of 1.3% and imprecision of 5.4% at the threshold. Ion suppression/enhancement never exceeded 7%. Calculating measurement uncertainty showed proof of applicability of the method. Stability of formoterol was also investigated at 56 °C (accelerated stability test) at pH 1.0/5.2/7.0 and 9.5. At the physiological pH values of 5.2 and 7.0, formoterol showed good stability. At pH 1.0 and 9.5 significant degradation was observed.

Time-of-day effect on hip flexibility associated with the modified sit-and- reach test in males.

Flexibility is a key component of physical fitness. It has been suggested that measures of physical fitness components may vary throughout the day. The aim of this study was to analyse the effects of the time of day on flexibility performance. 26 men (mean age=25.4 years, SD=2.5) were evaluated by hip flexion on kinematic analysis and also by an absolute score in the modified Sit-and-Reach test during a repeated measure design. This was done during 3 experimental sessions, which took place at 8:00 a.m., 1:00 p.m. and 6:00 p.m., in random order. All subjects were previously familiarized with the test parameters. There was a diurnal variation only in the modified Sit-and-Reach test score between 8:00 a.m and 6:00 p.m. (P=0.01). There was no significant difference in the hip kinematic analysis between hours. These findings suggest that flexibility performance in the modified Sit-and-Reach test, in absolute scores, is affected by the time of day, with higher performance in the evening.

Effects of imidacloprid exposure on Chironomus riparius Meigen larvae: linking acetylcholinesterase activity to behaviour.

Imidacloprid (IMI) is an insecticide that interferes with the transmission of stimuli in the nervous system of insects. It is neurotoxic by mimicking nicotine through its binding to the nicotinic acetylcholine receptor. In this work, experiments comprising 96 h exposure followed by 48 h in clean medium were conducted to evaluate the toxicity of IMI to Chironomus riparius and its potential recovery. Behavioural parameters and AChE activity were assessed. After 96 h exposure to IMI, AChE activity, and the behaviour parameters ventilation and locomotion were reduced. There were no signs of recovery after removal to clean water for 48 h. Ventilation behaviour was the most sensitive parameter and the one with the highest correlation to AChE activity. Despite the possibility that IMI might be having an indirect effect on AChE activity, the behavioural endpoint showed a higher sensitivity than the biochemical response itself. This work highlights the importance of linking parameters with ecological relevance at individual level (behavioural parameters) with biochemical responses, to unravel xenobiotics mode of action.

Consequences of the formation of 3,4-dimethyl-5-phenyl-1,3-oxazolidine on the analysis of ephedrines in urine by gas chromatography and a new method for confirmation as N-trifluoroacetyl-O-t-butyldimethylsilyl ether derivatives.

The compound 3,4-dimethyl-5-phenyl-1,3-oxazolidine can appear as an artifact during the gas chromatographic analysis of ephedrines. Its presence is a risk for doping control and forensic analyses. An evaluation about the consequences of its formation showed the possibility of a false positive for ephedrine, a false negative for pseudophedrine and increased uncertainty in the quantitative approach. Misinterpretations can be avoided with the observation of fragments m/z 56 and 71 in the ephedrine mass spectrum during GC-MS analysis and also by the formation of N-TFA-O-TBDMS derivatives prior to GC analysis. These N-TFA-O-TBDMS derivatives lead to an increase in the number and mass of diagnostic ions, meet the identification criteria, and provide an improvement in chromatographic resolution, allowing the separation of the ephedrines.

Analysis of sibutramine metabolites as N-trifluoroacetamide and O-trimethylsilyl derivatives by gas chromatography-mass spectrometry in urine.

A method for identifying the metabolites of sibutramine 1-(4(chlorophenyl)-N,N-dimethyl-alpha-(2-methylpropyl))cyclobutanemethanamine) in urine, utilizing a double derivatization strategy, with N-methyl-N-(trimethylsilyl)-trifluoroacetamide and N-methyl-bis-(trifluoroacetamide), in gas chromatography/mass spectrometry is proposed. This methodology results in mass spectra with at least three fragments in abundance superior to 20%, attending the World Anti-Doping Agency identification criteria for qualitative assays. The characterization of the derivatives was obtained through two ionization modes: Chemical Ionization and Electron Impact ionization, both in full scan mode. Sibutramine was administered to 5 (five) volunteers and the excretion profile followed for 92h. Routine analytical, hydroxy-cyclobutane-bis-nor-sibutramine which becomes the more abundant metabolite in the first 10h and hydroxy-isopropyl-bis-nor-sibutramine which becomes the most abundant after 40h, were proposed for doping monitoring.

Electromyographic activity of knee stabilizer muscles during six different balance board stimuli after anterior cruciate ligament surgery.

The purpose of this study was to compare the electrical activity of the knee stabilizers, in patients with ACL (anterior cruciate ligament) reconstructed and uninjured individuals during different balance board stimuli. Eleven post-surgery individuals and eleven uninjured controls participated in the study. The muscular activity of the vastus medialis obliquus, vastus lateralis, semitendinosus, biceps femoris and gastrocnemius medial were analyzed by surface electromyography during the execution of six different balance board activities. All electromyographic data were reported as percentage of RMS mean values obtained in maximal voluntary isometric contractions (MVIC) for each muscle. When comparing the individuals with ACL reconstructed and uninjured controls, minor electromyographic activity was observed (MVIC %) for all the muscles in the surgery group (P < 0.05), however, when comparing each exercise between the groups, a statistically significant difference for vastus lateralis was demonstrated in the floor exercise (P = 0.02) and for gastrocnemius on the round board (P = 0.04). Individuals ACL reconstructed presented a decrease in muscular activity during different balance board stimuli, which suggests that compensatory alterations after ACL may still exist even after a surgery to repair an ACL rupture.

Analytical challenges in doping control: Comprehensive two-dimensional gas chromatography with time of flight mass spectrometry, a promising option.

Doping control screening based on the enhanced resolution of comprehensive two-dimensional (2D) gas chromatography hyphenated to time of flight mass spectrometer was investigated. The identification of anabolic agents (clenbuterol, norandrosterone, epimetendiol, two methyltestosterone metabolites and 3'-hydroxystanozolol) contained in a spiked urine sample (2ng/ml) was demonstrated. Special emphasis was given to 3'-hydroxystanozolol, mainly considering the difficulty in its detection. In contrast to conventional GC-MS approaches that must use single-ion monitoring, the GC x GC-TOFMS method enabled the identification of that metabolite through the deconvolution of the full mass spectrum and also resolved the co-eluted peaks of 3'-hydroxystanozolol and an endogenous component.

Crystal structure of calf spleen purine nucleoside phosphorylase complexed to a novel purine analogue.

The combined use of a rapid virtual screen of a small fragment library together with a single point enzyme assay has been used for the discovery of novel PNP inhibitors. The availability of readily soakable crystals of bovine PNP has allowed the approach to be experimentally validated by determining the crystal structure of one of the inhibitor-PNP complexes. Comparison of the experimentally determined binding mode with that predicted by the virtual screening shows them to be similar. This represents a starting point for the growth of the ligand into a higher affinity inhibitor.

A Rare Variation of the Retro-Aortic Left Renal Vein with Anastomotic Afluent from Inferior Mesenteric Vein / Una Variación Rara de la Vena Renal Izquierda Retro-Aórtica con un Afluente Anastomótico de la Vena Mesentérica Inferior

We report an uncommon anatomical variations of the left renal vein was found on dissected specimen in an elderly male cadaver: a retroaortic left renal vein. No other vascular anomalies were noted in this specimen. The anomaly result may be related to a particular pattern of left inferior vena cava. The abnormality have to be known for it may be undetected or be misleading in imaging. This anatomical curiosity should be kept in mind by clinicians and academics that may manipulate this anatomical area.

Relatamos una variación anatómica infrecuente de la vena renal izquierda, denominada vena renal retroaórtica, encontrada en un cadáver masculino disecado. No se observaron otras variaciones vasculares. Lavariación anatómica encontrada se puede relacionar con un patrón particular de la vena cava inferior izquierda. La variación debe ser conocida ya que puede pasar inadvertida o ser confundida en proyecciones de imágenes de la región. Los clínicos y académicos que actúen en la región, deben considerar esta eventual variación anatómica.

Chromosomal G-dark bands determine the spatial organization of centromeric heterochromatin in the nucleus.

Gene expression can be silenced by proximity to heterochromatin blocks containing centromeric alpha-satellite DNA. This has been shown experimentally through cis-acting chromosome rearrangements resulting in linear genomic proximity, or through trans-acting changes resulting in intranuclear spatial proximity. Although it has long been been established that centromeres are nonrandomly distributed during interphase, little is known of what determines the three-dimensional organization of these silencing domains in the nucleus. Here, we propose a model that predicts the intranuclear positioning of centromeric heterochromatin for each individual chromosome. With the use of fluorescence in situ hybridization and confocal microscopy, we show that the distribution of centromeric alpha-satellite DNA in human lymphoid cells synchronized at G(0)/G(1) is unique for most individual chromosomes. Regression analysis reveals a tight correlation between nuclear distribution of centromeric alpha-satellite DNA and the presence of G-dark bands in the corresponding chromosome. Centromeres surrounded by G-dark bands are preferentially located at the nuclear periphery, whereas centromeres of chromosomes with a lower content of G-dark bands tend to be localized at the nucleolus. Consistent with the model, a t(11; 14) translocation that removes G-dark bands from chromosome 11 causes a repositioning of the centromere, which becomes less frequently localized at the nuclear periphery and more frequently associated with the nucleolus. The data suggest that "chromosomal environment" plays a key role in the intranuclear organization of centromeric heterochromatin. Our model further predicts that facultative heterochromatinization of distinct genomic regions may contribute to cell-type specific patterns of centromere localization.

A trade-off in task allocation between sensitivity to the environment and response time.

Task allocation is the process that adjusts the number of workers in each colony task in response to the environment. There is no central coordination of task allocation; instead workers use local cues from the environment and from other workers to decide which task to perform. We examine two aspects of task allocation: the sensitivity to the environment of task distribution, and the rate of response to environmental changes. We investigate how these two aspects are influenced by: (1) colony size, and (2) behavioral rules used by workers, i.e. how a worker uses cues from the environment and from social interactions with other workers in deciding which task to perform. We show that if workers use social cues in their choice of task, response time decreases with increasing colony size. Sensitivity of task distribution to the environment may decrease or not with colony size, depending on the behavioral rules used by workers. This produces a trade-off in task allocation: short response times can be achieved by increasing colony size, but at the cost of decreased sensitivity to the environment. We show that when a worker's response to social interactions depends on the local environment, sensitivity of task distribution to the environment is not affected by colony size and the trade-off is avoided.

Collagen/collagenase interaction: does the enzyme mimic the conformation of its own substrate?

In this report, we present a hypothesis on the mechanism used by interstitial collagenases to cleave their natural substrate, interstitial collagens. The hypothesis is based on the assumption that the proline hinge domain of interstitial collagenase adopts a collagen-like conformation. With a collagen-like domain, the enzyme is able to disturb the quaternary organization of the triple helix in the collagenase-susceptible site. A modeling analysis suggests that interaction between prolines of both collagen and collagenase forming a kind of "proline zipper" is involved in the destabilization step. This destabilization makes the three-collagen helix susceptible to the catalytic cleft of the catalytic core.