Trace analysis of N‐acetyl‐L‐cysteine using luminol–H2O2 chemiluminescence system catalyzed by silver nanoparticles

N‐Acetyl‐L‐cysteine (NAC) can inhibit the luminol–H₂O₂, reaction, which is catalyzed by silver nanoparticles. Based on this phenomenon a new method was developed for NAC determination. Under optimum conditions, a linear relationship between chemiluminescence intensity and NAC concentration was found in the range 0.034–0.98 µg/mL. The detection limit was 0.010 µg/mL (S/N =3), and the relative standard deviation (RSD) was <5% for 0.480 µg/mL NAC (n =5). This simple, sensitive and inexpensive method has been applied to measure the concentration of NAC in pharmaceutical tablets. Copyright © 2014 John Wiley & Sons, Ltd.     

Prevalence of Pulmonary Hypertension in the General Population: The Rotterdam Study

Background

Pulmonary hypertension is characterized by increased pulmonary artery pressure and carries an increased mortality. Population-based studies into pulmonary hypertension are scarce and little is known about its prevalence in the general population. We aimed to describe the distribution of echocardiographically-assessed pulmonary artery systolic pressure (ePASP) in the general population, to estimate the prevalence of pulmonary hypertension, and to identify associated factors.

Methods

Participants (n = 3381, mean age 76.4 years, 59% women) from the Rotterdam Study, a population-based cohort, underwent echocardiography. Echocardiographic pulmonary hypertension was defined as ePASP>40 mmHg.

Results

Mean ePASP was 26.3 mmHg (SD 7.0). Prevalence of echocardiographic pulmonary hypertension was 2.6% (95%CI: 2.0; 3.2). Prevalence was higher in older participants compared to younger ones (8.3% in those over 85 years versus 0.8% in those between 65 and 70), and in those with underlying disorders versus those without (5.9% in subjects with COPD versus 2.3%; 9.2% in those with left ventricular systolic dysfunction versus 2.3%; 23.1% in stages 3 or 4 left ventricular diastolic dysfunction versus 1.9% in normal or stage 1). Factors independently associated with higher ePASP were older age, higher BMI, left ventricular diastolic dysfunction, COPD and systemic hypertension.

Conclusion

In this large population-based study, we show that pulmonary hypertension as measured by echocardiography has a low prevalence in the overall general population in the Netherlands, but estimates may be higher in specific subgroups, especially in those with underlying diseases. Increased pulmonary arterial pressure is likely to gain importance in the near future due to population aging and the accompanying prevalences of underlying disorders.     

The L33F darunavir resistance mutation acts as a molecular anchor reducing the flexibility of the HIV-1 protease 30s and 80s loops

HIV-1 protease (PR) is a 99 amino acid protein responsible for proteolytic processing of the viral polyprotein – an essential step in the HIV-1 life cycle. Drug resistance mutations in PR that are selected during antiretroviral therapy lead to reduced efficacy of protease inhibitors (PI) including darunavir (DRV). To identify the structural mechanisms associated with the DRV resistance mutation L33F, we performed X-ray crystallographic studies with a multi-drug resistant HIV-1 protease isolate that contains the L33F mutation (MDR769 L33F). In contrast to other PR L33F DRV complexes, the structure of MDR769 L33F complexed with DRV reported here displays the protease flaps in an open conformation. The L33F mutation increases noncovalent interactions in the hydrophobic pocket of the PR compared to the wild-type (WT) structure. As a result, L33F appears to act as a molecular anchor, reducing the flexibility of the 30s loop (residues 29–35) and the 80s loop (residues 79–84). Molecular anchoring of the 30s and 80s loops leaves an open S1/S1′ subsite and distorts the conserved hydrogen-bonding network of DRV. These findings are consistent with previous reports despite structural differences with regards to flap conformation.     

Robust and stable feature selection by integrating ranking methods and wrapper technique in genetic data classification

High dimensional data increase the dimension of space and consequently the computational complexity and result in lower generalization. From these types of classification problems microarray data classification can be mentioned. Microarrays contain genetic and biological data which can be used to diagnose diseases including various types of cancers and tumors. Having intractable dimensions, dimension reduction process is necessary on these data. The main goal of this paper is to provide a method for dimension reduction and classification of genetic data sets. The proposed approach includes different stages. In the first stage, several feature ranking methods are fused for enhancing the robustness and stability of feature selection process. Wrapper method is combined with the proposed hybrid ranking method to embed the interaction between genes. Afterwards, the classification process is applied using support vector machine. Before feeding the data to the SVM classifier the problem of imbalance classes of data in the training phase should be overcame. The experimental results of the proposed approach on five microarray databases show that the robustness metric of the feature selection process is in the interval of [0.70, 0.88]. Also the classification accuracy is in the range of [91%, 96%].     

Viscoelasticity of Tau Proteins Leads to Strain Rate-Dependent Breaking of Microtubules during Axonal Stretch Injury: Predictions from a Mathematical Model

The unique viscoelastic nature of axons is thought to underlie selective vulnerability to damage during traumatic brain injury. In particular, dynamic loading of axons has been shown to mechanically break microtubules at the time of injury. However, the mechanism of this rate-dependent response has remained elusive. Here, we present a microstructural model of the axonal cytoskeleton to quantitatively elucidate the interaction between microtubules and tau proteins under mechanical loading. Mirroring the axon ultrastructure, the microtubules were arranged in staggered arrays, cross-linked by tau proteins. We found that the viscoelastic behavior specifically of tau proteins leads to mechanical breaking of microtubules at high strain rates, whereas extension of tau allows for reversible sliding of microtubules without any damage at small strain rates. Based on the stiffness and viscosity of tau proteins inferred from single-molecule force spectroscopy studies, we predict the critical strain rate for microtubule breaking to be in the range 22–44 s⁻¹, in excellent agreement with recent experiments on dynamic loading of micropatterned neuronal cultures. We also identified a characteristic length scale for load transfer that depends on microstructural properties and have derived a phase diagram in the parameter space spanned by loading rate and microtubule length that demarcates those regions where axons can be loaded and unloaded reversibly and those where axons are injured due to breaking of the microtubules.     

Biology of Lysiphlebus fabarum following cold storage of larvae and pupae

Cold storage is one means of preserving parasitoids prior to release in augmentation biological control programs. This study examined the feasibility of storing larval and pupal stages of a sexual population of Lysiphlebus fabarum Marshall (Hymenoptera: Braconidae: Aphidiinae) at 6 ± 1 and 8 ± 1 °C, 50–60% r.h., and L14:D10 photoperiod. These life stages were stored for periods of 1, 2, and 3 weeks under fluctuating thermal regimes (2 h daily at 21 ± 1 °C). Generally, pupae gave better results than larvae, and 6 °C was better than 8 °C, considering wasp survival, wasp size (tibial and antennal lengths), egg load, and egg size. The best results were obtained with pupae stored for 2 weeks under a fluctuating temperature regime at 6 °C. Females emerging from this treatment did not differ from controls (developing directly at 21 °C) in body size, egg size, or progeny sex ratio, and suffered less than 20% mortality. Egg loads were reduced in these wasps, but the reductions were substantially less than occurred in other 2‐week‐storage treatments. Wasps stored in this manner successfully parasitized similar numbers of aphids as controls and produced similar progeny sex ratios. These results reveal a suitable set of low‐temperature conditions that can be used to delay the development of L. fabarum for 2 weeks with minimal impact on wasp fitness.     

Foraminifera and their associations of a possibly Rhaetian section of the Nayband Formation in central Iran,northeast of Esfahan

The following paper describes the foraminiferal fauna and associated faunal assemblages of the bedded and reef carbonates of the Upper Triassic (most probably Rhaetian) Nayband Formation, which are exposed in a section south of the small town of Bagher-Abad, northeast of Esfahan. Foraminifers are extremely rare in sponge- or coral-dominated bioconstructions and in the bedded carbonates of the Nayband Formation in central Iran. Some carbonate beds are composed of bioclastic wackstone/packstone. These are exposed in the solenoporacean horizon at the uppermost part of the section. Here, the aulotortid- and trocholinid-type foraminifers are relatively abundant. The following foraminiferal taxa with different abundances were found within the carbonates of the investigated section: Trocholina umbo Frentzen, T. turris Frentzen, T. gracilis Blau, Aulotortus tumidus (Kristan-Tollmann), Aulotortus tenuis (Kristan), Aulotortus friedli (Kristan-Tollmann), Coronipora etrusca (Pirini), Semiinvoluta clari Kristan, Turrispirillina? licia variabilis Blau, Galeanella? laticarinata Al-Shaibani, Carter and Zaninetti, Ophthalmidium sp., Agathammina sp., “Sigmoilina” schaeferae Zaninetti, Planiinvoluta carinata Leischner, Planiinvoluta sp., Nubecularia sp., Endothyra sp., Paeolituonella sp. and some sessile agglutinated and nodosariid types. All mentioned taxa are very rare, except the involutinid and trocholinid types. The following species are described as new: Trocholina blaui nov. sp., Spirilina? iranica nov. sp., and Coronipora serraforma nov. sp. Trocholina blaui is usually attached to solenoporacean thalli. Four foraminiferal associations, which are named after the occurrence of the abundant species, were distinguished as Aulotortus tumidus association, Aulotortus friedli association, Trocholina umbo association, and Trocholina blaui association. Aulotortid types and Trocholina umbo were found within the bioclastic wackstone/packstone carbonates. Trocholina blaui is abundant in solenoporacean framestones. The foraminiferal association of investigated carbonates contains a mixed fauna, known from Upper Triassic–Liassic in the Tethyan realm. Carbonates of the whole investigated section are dated—due to occurrence of the genus Aulotortus, with species A. tumidus (Kristan-Tollmann), A. tenuis (Kristan), and A. friedli (Kristan-Tollmann)—as Upper Triassic (most probably Rhaetian). The “typical” foraminifers occurring in the reef biotopes in the northwestern Tethys are either missing or extremely rare in the Iranian bioconstructions.     

Sperm status and DNA dose play key roles in sperm/ICSI‐mediated gene transfer in caprine

In relation to the growing recent interest in the establishment of sperm‐mediated gene transfer (SMGT) technology as a convenient and effective method for the simple production of transgenic animals, in this study the possibility of using SMGT to produce transgenic caprine embryos was investigated for the first time. Buck sperm were directly incubated with different concentrations (0–500 ng) of pcDNA/his/Lac‐Z plasmid and used for IVF or ICSI. Sperm used for ICSI were categorized into motile or live‐immotile group before being injected into oocytes. In a separate experiment, dead sperm prepared by repeated freezing/thawing were used for DNA‐incubation before ICSI. Sham injection was carried out by intracytoplasmic injection of approximately the same volume of media containing different doses of DNA using an ICSI needle. Transgene expression and transmission were detected by X‐Gal staining and PCR analysis of developed embryos, respectively. A reasonable blastocyst rate was observed in all the groups. Only embryos in the sham group were negative for transgene transmission. Transgene expression was completely dependent on the delivery technique and status of sperm, and was only observed in the live‐immotile and dead ICSI groups. The results of this study showed that the technique (IVF vs. ICSI vs. sham injection), sperm status (motile vs. live‐immotile vs. dead) and to some extent DNA concentration affect embryo development, transgene transmission and expression. Mol. Reprod. Dev. 77:868–875, 2010. © 2010 Wiley‐Liss, Inc.     

Genetic structure of the xerophilous bromeliad Pitcairnia geyskesii on inselbergs in French Guiana – a test of the forest refuge hypothesis

Inselbergs are isolated granitic rock outcrops that provide distinctive ecological conditions. In northern South America they rise above the surrounding rainforest. Among inselberg specialists, Pitcairnia geyskesii (Bromeliaceae) is restricted to these habitats in French Guiana. We studied populations from 12 inselbergs using 7 microsatellite loci to give a "reverse image" of the reduction-expansion of the rainforest in the context of the refuge hypothesis. Our analyses showed that populations are fragmented with dispersal occurring only over very short distances. Genetic diversity was higher in northern French Guiana, whereas specific alleles were observed in the south. The results point to the occurrence of a dry corridor in the north, as hypothesized by Tardy (1998) based on charcoal analyses, whereas de Granville's (1982) hypothesis of a unique past refuge is not confirmed. Moreover, our data suggests the importance of Oyapock River as a pathway for range expansion, arguing against the potential role of the Inini-Camopi Mountains as a physical barrier. Finally, in spite of a strongly argued scenario in favour of a north-to-south migration history, a clear genetic isolation of P. geyskesii populations living on inselbergs of the Mitaraka archipelago suggests a distinct ancestry of the most southern populations.     

Shotgun strategy-based proteome profiling analysis on the head of silkworm Bombyx mori

Insect head is comprised of important sensory systems to communicate with internal and external environment and endocrine organs such as brain and corpus allatum to regulate insect growth and development. To comprehensively understand how all these components act and interact within the head, it is necessary to investigate their molecular basis at protein level. Here, the spectra of peptides digested from silkworm larval heads were obtained from liquid chromatography tandem mass spectrometry (LC–MS/MS) and were analyzed by bioinformatics methods. Totally, 539 proteins with a low false discovery rate (FDR) were identified by searching against an in-house database with SEQUEST and X!Tandem algorithms followed by trans-proteomic pipeline (TPP) validation. Forty-three proteins had the theoretical isoelectric point (pI) greater than 10 which were too difficult to separate by two-dimensional gel electrophoresis (2-DE). Four chemosensory proteins, one odorant-binding protein, two diapause-related proteins, and a lot of cuticle proteins, interestingly including pupal cuticle proteins were identified. The proteins involved in nervous system development, stress response, apoptosis and so forth were related to the physiological status of head. Pathway analysis revealed that many proteins were highly homologous with the human proteins which involved in human neurodegenerative disease pathways, probably implying a symptom of the forthcoming metamorphosis of silkworm. These data and the analysis methods were expected to be of benefit to the proteomics research of silkworm and other insects.