Rapid and sensitive method for the determination of acetaldehyde in fuel ethanol by high-performance liquid chromatography with UV-Vis detection

A high-performance liquid chromatography (HPLC) method for the determination of acetaldehyde in fuel ethanol was developed. Acetaldehyde was derivatized with 0.900 mL 2,4-dinitrophenylhydrazine (DNPHi) reagent and 50 mu L phosphoric acid 1 mol L-1 at a controlled room temperature of 15 degrees C for 20 min. The separation of acetaldehyde- DNPH (ADNPH) was carried out on a Shimadzu Shim-pack C-18 column, using methanol/LiCl(aq) 1.0 mM (80/20, v/v) as a mobile phase under isocratic elution and UV-Vis detection at 365 nm. The standard curve of ADNPH was linear in the range 3-300 amg L-1 per injection (20 mu L) and the limit of detection (LOD) for acetaldehyde was 2.03 mu g L-1, with a correlation coefficient greater than 0.999 and a precision (relative standard deviation, RSD) of 5.6% (n=5). Recovery studies were performed by fortifying fuel samples with acetaldehyde at various concentrations and the results were in the range 98.7-102%, with a coefficient of variation (CV) from 0.2% to 7.2%. Several fuel samples collected from various gas stations were analyzed and the method was successfully applied to the analysis of acetaldehyde in fuel ethanol samples.

Isolation and characterisation of cycloheximide sensitive mutants of Aspergillus nidulans

Aspergillus nidulans is a non-pathogenic fungus with well-developed genetics which provides an excellent model system for studying different aspects of drug resistance in filamentous fungi. As a preliminary step to characterizing genes that confer pleiotropic drug resistance in Aspergillus, we isolated cycloheximide-sensitive mutants of A. nidulans, which is normally resistant to this: drug. The rationale for this approach is to identify gents whose products are important for drug resistance by analysing mutations that alter the resistance/sensitivity status of the cell. Fifteen cycloheximide-sensitive (named scy for sensitive to cycloheximide) mutants of A, nidulans were isolated and genetically characterised. Each scy mutant was crossed with the wild-type strain and five of the crosses gave 50% cycloheximide-sensitive progeny suggesting that they carry a single mutation required for cycloheximide sensitivity. We examined ten sep mutants for resistance/sensitivity to other drugs or stress agents with different and/or the same mechanism of action, Sis of these mutants exhibited other altered resistance/sensitivity phenotypes which were linked to the cycloheximide sensitivity, These six mutants were analyzed by pairwise crosses and found to represent six linkage groups, named scyA-F. One of the mutants showed fragmentation of its vacuolar system and, in addition, its growth was osmotic, low-pi-II and oxidative-stress sensitive.

Serum and plasma hormonal concentrations are sensitive to periods of intensity and volume of soccer training

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of sex and locality on the abundance of lice on the wild rodent Oligoryzomys nigripes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sensitive Affimer and Antibody Based Impedimetric Label-Free Assays for C-Reactive Protein

C-reactive protein (CRP) is an acute phase protein whose levels are increased in many disorders. Levels greater than 3 mu g/mL serum have hitherto been considered to indicate pathology, but there is increasing interest in assessments between 0.1 and 10 mu g/mL, which have been found to correlate with severity of risk for cardiovascular disease. We report herein the generation of both antibody and Affimer based impedance immunoassays for CRP that are substantially more sensitive than clinically utilized immunonephelometry and immunoturbidity assessments. Significant in this study is not only the use of a constrained peptide to detect a clinically important target but also that derived electrochemical impedance assays can be highly sensitive even with probes whose relatively weak (mu M) affinities are not amenable to target detection by surface plasmon resonance (SPR). Key to this finding is acknowledging that receptive surfaces of comparatively low initial steric bulk and charge transfer resistance are especially primed to be highly responsive to target binding in electroanalytical assays of this type.

Bell's locality condition confronting perfect anti-correlations

We show that Local Realistic Theories, defined as obeying the Bells's locality condition, cannot satisfy the prefect anti-correlations without at the same time maximally violating rotational symmetry at the hidden variable level. We examine whether the rotational symmetry can be restored after the statistical average. We also comment on the question whether such theories are necessarily deterministic at the hidden variable leva. © 1999 Elsevier Science B.V. All rights reserved.

The dermatophyte Trichophyton rubrum secretes an EDTA-sensitive alkaline phosphatase on high-phosphate medium

In this communication, we show that the growth of isolate H6 of the dermatophyte Trichophyton rubrum on non-buffered medium and under saturating phosphate conditions is dependent on the initial growth pH, with an apparent optimum at pH 4.0. In addition, irrespective of the initial growth pH, the pH of the medium altered during cultivation reaching values that ranged from 8.3 to 8.9. Furthermore, this isolate synthesized and secreted almost the same levels of an alkaline phosphatase with an apparent optimum pH ranging from 9.0 to 10.0 when grown on both low- and high-phosphate medium. Also, this alkaline phosphatase is activated by Mg2+ and is EDTA-sensitive. On the other hand, the very low levels of the enzyme retained by the mycelium grown on buffered medium at pH 5.0-5.2 suggest that this enzyme is encoded by an alkaline gene, i.e., a gene responsive to ambient pH signaling.

The influence of the loop between residues 223-235 in beetle luciferase bioluminescence spectra: A solvent gate for the active site of pH-sensitive luciferases

Beetle luciferases emit a wide range of bioluminescence colors, ranging from green to red. Firefly luciferases can shift the spectrum to red in response to pH and temperature changes, whereas click beetle and railroadworm luciferases do not. Despite many studies on firefly luciferases, the origin of pH-sensitivity is far from being understood. Through comparative site-directed mutagenesis and modeling studies, using the pH-sensitive luciferases (Macrolampis and Cratomorphus distinctus fireflies) and the pH-insensitive luciferases (Pyrearinus termitilluminans, Phrixotrix viviani and Phrixotrix hirtus) cloned by our group, here we show that substitutions dramatically affecting bioluminescence colors in both groups of luciferases are clustered in the loop between residues 223-235 (Photinus pyralis sequence). The substitutions at positions 227, 228 and 229 (P. pyralis sequence) cause dramatic redshift and temporal shift in both groups of luciferases, indicating their involvement in labile interactions. Modeling studies showed that the residues Y227 and N229 are buried in the protein core, fixing the loop to other structural elements participating at the bottom of the luciferin binding site. Changes in pH and temperature (in firefly luciferases), as well as point mutations in this loop, may disrupt the interactions of these structural elements exposing the active site and modulating bioluminescence colors. © 2007 The Authors.

Context-sensitive analysis of obfuscated x86 executables

A method for context-sensitive analysis of binaries that may have obfuscated procedure call and return operations is presented. Such binaries may use operators to directly manipulate stack instead of using native call and ret instructions to achieve equivalent behavior. Since definition of context-sensitivity and algorithms for context-sensitive analysis have thus far been based on the specific semantics associated to procedure call and return operations, classic interprocedural analyses cannot be used reliably for analyzing programs in which these operations cannot be discerned. A new notion of context-sensitivity is introduced that is based on the state of the stack at any instruction. While changes in 'calling'-context are associated with transfer of control, and hence can be reasoned in terms of paths in an interprocedural control flow graph (ICFG), the same is not true of changes in 'stack'-context. An abstract interpretation based framework is developed to reason about stack-contexts and to derive analogues of call-strings based methods for the context-sensitive analysis using stack-context. The method presented is used to create a context-sensitive version of Venable et al.'s algorithm for detecting obfuscated calls. Experimental results show that the context-sensitive version of the algorithm generates more precise results and is also computationally more efficient than its context-insensitive counterpart. Copyright © 2010 ACM.

Context-sensitive analysis without calling-context

Since Sharir and Pnueli, algorithms for context-sensitivity have been defined in terms of 'valid' paths in an interprocedural flow graph. The definition of valid paths requires atomic call and ret statements, and encapsulated procedures. Thus, the resulting algorithms are not directly applicable when behavior similar to call and ret instructions may be realized using non-atomic statements, or when procedures do not have rigid boundaries, such as with programs in low level languages like assembly or RTL. We present a framework for context-sensitive analysis that requires neither atomic call and ret instructions, nor encapsulated procedures. The framework presented decouples the transfer of control semantics and the context manipulation semantics of statements. A new definition of context-sensitivity, called stack contexts, is developed. A stack context, which is defined using trace semantics, is more general than Sharir and Pnueli's interprocedural path based calling-context. An abstract interpretation based framework is developed to reason about stack-contexts and to derive analogues of calling-context based algorithms using stack-context. The framework presented is suitable for deriving algorithms for analyzing binary programs, such as malware, that employ obfuscations with the deliberate intent of defeating automated analysis. The framework is used to create a context-sensitive version of Venable et al.'s algorithm for analyzing x86 binaries without requiring that a binary conforms to a standard compilation model for maintaining procedures, calls, and returns. Experimental results show that a context-sensitive analysis using stack-context performs just as well for programs where the use of Sharir and Pnueli's calling-context produces correct approximations. However, if those programs are transformed to use call obfuscations, a contextsensitive analysis using stack-context still provides the same, correct results and without any additional overhead. © Springer Science+Business Media, LLC 2011.

Intriguing thigmonastic (sensitive) stamens in the Plains Prickly Pear Opuntia polyacantha (Cactaceae)

The movement of sensitive stamens in flowers of the Plains Prickly Pear (Opuntia polyacantha) is described in detail along with the external and internal filament anatomy. The goals of this investigation were: (1) to provide a synthesis of floral phenology and determine whether this rather unique stamen movement is nastic or a tropism and (2) to conduct macro- and micro-morphological analyses of filaments to determine if there are anatomical traits associated with this movement. To better understand the internal and external structure in sensitive filaments of O. polyacantha, we performed comparative anatomical analyses in two additional species from the Opuntioideae with stamens lacking such sensitivity. The consistent unidirectional movement of stamens, independent of the area stimulated, indicates a thigmonastic response. This movement serves multiple purposes, from enhancing pollen presentation to facilitating cross-pollination, protecting pollen and preventing insects from robbing pollen. Anatomically, the sensitive and non-sensitive filaments exhibit different tissue organization. Cuticle thickness, presence of capsular structures, two layers of curved cells, and more and larger intercellular spaces are characteristic of sensitive filaments. A thin unicellular epidermal layer is characteristic in sensitive filaments versus 2-3 epidermal layers in non-sensitive filaments. Another striking feature in sensitive filaments is the presence of papillae and capsular structures. We believe that these elements are related to water mobility with subsequent contraction during the thigmonastic response. Capsular structures might have a role in fluid mobility according to the stimulus of the filaments. We hypothesize that the thigmonastic response is controlled by cells with elastic properties, as evidenced by the plasmolyzed curved and contracted cells in the filaments and the fact that the movement is activated by changes in cell turgor followed by contraction as a result of plasmolysis. © 2013 Elsevier GmbH.

Sensitive voltammetric sensor for fast detection of mycolic acids present in mycobacteria

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Search for methylation-sensitive amplification polymorphisms in mutant figs

Fig (Ficus carica) breeding programs that use conventional approaches to develop new cultivars are rare, owing to limited genetic variability and the difficulty in obtaining plants via gamete fusion. Cytosine methylation in plants leads to gene repression, thereby affecting transcription without changing the DNA sequence. Previous studies using random amplification of polymorphic DNA and amplified fragment length polymorphism markers revealed no polymorphisms among select fig mutants that originated from gamma-irradiated buds. Therefore, we conducted methylation-sensitive amplified polymorphism analysis to verify the existence of variability due to epigenetic DNA methylation among these mutant selections compared to the main cultivar 'Roxo-de-Valinhos'. Samples of genomic DNA were double-digested with either HpaII (methylation sensitive) or MspI (methylation insensitive) and with EcoRI. Fourteen primer combinations were tested, and on an average, non-methylated CCGG, symmetrically methylated CmCGG, and hemimethylated hmCCGG sites accounted for 87.9, 10.1, and 2.0%, respectively. MSAP analysis was effective in detecting differentially methylated sites in the genomic DNA of fig mutants, and methylation may be responsible for the phenotypic variation between treatments. Further analyses such as polymorphic DNA sequencing are necessary to validate these differences, standardize the regions of methylation, and analyze reads using bioinformatic tools. © FUNPEC-RP.

Context-sensitive analysis of x86 obfuscated executables

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Serum cystatin C is a sensitive early marker for changes in the glomerular filtration rate in patients undergoing laparoscopic surgery

OBJECTIVE: Pneumoperitoneum during laparoscopy results in transient oliguria and decreased glomerular filtration and renal blood flow. The presence of oliguria and elevated serum creatinine is suggestive of acute renal injury. Serum cystatin C has been described as a new marker for the detection of this type of injury. In this study, our aim was to compare the glomerular filtration rate estimated using cystatin C levels with the rate estimated using serum creatinine in patients with normal renal function who were undergoing laparoscopic surgery. METHODS: In total, 41 patients undergoing laparoscopic cholecystectomy or hiatoplasty were recruited for the study. Blood samples were collected at three time intervals: first, before intubation (T1); second, 30 minutes after the establishment of pneumoperitoneum (T2); and third, 30 minutes after deflation of the pneumoperitoneum (T3). These blood samples were then analyzed for serum cystatin C, creatinine, and vasopressin. The Larsson formula was used to calculate the glomerular filtration rate based on the serum cystatin C levels, and the Cockcroft-Gault formula was used to calculate the glomerular filtration rate according to the serum creatinine levels. RESULTS: Serum cystatin C levels increased during the study (T1 = T2T3; p<0.05). The calculated eGlomerular filtration rate-Larsson decreased, whereas the eGlomerular filtration rate-Cockcroft-Gault increased. There was no correlation between cystatin C and serum creatinine. Additionally, Pearson's analysis showed a better correlation between serum cystatin C and the eGlomerular filtration rate than between serum creatinine and the eGlomerular filtration rate. CONCLUSION: This study demonstrates that serum cystatin C is a more sensitive indicator of changes in the glomerular filtration rate than serum creatinine is in patients with normal renal function who are undergoing laparoscopic procedures.