Development of a new high-performance liquid chromatography-electrospray ionization time-of-flight mass spectrometry method for the determination of low molecular mass organic acids in plant tissue extracts

A liquid chromatography-electrospray ionization time-of-flight mass spectrometry method has been developed for the direct and simultaneous determination of 10 low molecular mass organic acids in different plant tissue extracts. The method does not include a derivatization step. Quantification was accomplished using (13)C-labeled malic and succinic acids as internal standards. Good limits of detection (0.05-1.27 pmol) were obtained for malic, 2-oxoglutaric, succinic, quinic, shikimic, cis-aconitic, and citric acids, whereas for oxalic, ascorbic, and fumaric acids limits of detection were 255, 25, and 11 pmol, respectively. Repeatability values for the retention time and peak area were <5%, with the exception of ascorbic acid. Analyte recovery was between 92% and 110% in most cases, with the exception of oxalic (39-108%), 2-oxoglutaric (44-69%), and ascorbic (22-86%) acids, which may require specific extraction procedures and use of the corresponding (13)C-labeled organic acid as internal standards to improve accuracy. The method was applied to three types of plant materials: sugar beet leaf extracts, tomato xylem sap, and commercial orange juice.     

Understory herb assemblages 25 and 60 years after clearcutting of a northern hardwood forest, USA

The abundance of understory herbs in 25- and 60-year old clearcuts was compared to adjacent old secondary stands to infer how herb assemblages change in space and time following clearcutting of secondary forest. Herb densities and environmental conditions were sampled along 100 m transects crossing the clearcut/old secondary forest boundary, at three sites with 25-year old clearcuts and three sites with 60-year old clearcuts. At the 25-year sites, species densities of the 23 most frequent species were compared between clearcuts and adjacent old secondary forest to classify species into response groups. Species were classed as “insensitive” if there was little or no difference in density (seven species), “sensitive” if densities were lower in the clearcuts (six species), “enhanced” if densities were higher in clearcuts (four species), and “edge-enhanced” if densities were highest near clearcut edges (six species). Densities of two of the six sensitive species declined significantly with distance from the edge into the clearcut. Further, when regression results for all 23 species were combined, the mean slope of density vs. distance was significantly negative, indicating an overall trend to lower density with distance into the clearcuts. Most species classed as sensitive at 25 years did not show similar sensitivity at the 60-year sites; only one species had lower density in 60-year clearcuts than adjacent old secondary stands. Overall, there were substantial residual effects of clearcutting on herb assemblages within 50 m of the historical edge at 25-year sites, but not at 60-year sites. This difference may be due to different logging practices at the two historical times, as well as the difference in time for recovery since logging.     

Complex patterning by vertical interchange atom manipulation using atomic force microscopy

The ability to incorporate individual atoms in a surface following predetermined arrangements may bring future atom-based technological enterprises closer to reality. Here, we report the assembling of complex atomic patterns at room temperature by the vertical interchange of atoms between the tip apex of an atomic force microscope and a semiconductor surface. At variance with previous methods, these manipulations were produced by exploring the repulsive part of the short-range chemical interaction between the closest tip-surface atoms. By using first-principles calculations, we clarified the basic mechanisms behind the vertical interchange of atoms, characterizing the key atomistic processes involved and estimating the magnitude of the energy barriers between the relevant atomic configurations that leads to these manipulations.     

Dermatophytosis caused by Trichophyton benhamiae in a dog

Trichophyton benhamiae was diagnosed in a 9-year-old female dog by histopathological evaluation, fungal culture and confirmation by sequencing of the internal transcribed spacer region of ribosomal DNA. Successful therapy was achieved with itraconazole, bathing with miconazole and chlorhexidine shampoo, and topical application of sodium hypochlorite as a rinse.     

Pulmonary function and metabolic physiology of theropod dinosaurs

Ultraviolet light analysis of a fossil of the theropod dinosaur Scipionyx samniticus revealed that the liver subdivided the visceral cavity into distinct anterior pleuropericardial and posterior abdominal regions. In addition, Scipionyx apparently had diaphragmatic musculature and a dorsally attached posterior colon. These features provide evidence that diaphragm-assisted lung ventilation was present in theropods and that these dinosaurs may have used a pattern of exercise physiology unlike that in any group of living tetrapods.     

Ciprofloxacin and norfloxacin pharmacokinetics and prostatic fluid penetration in dogs after multiple oral dosing

The aims of this study were to assess the pharmacokinetics and pharmacokinetic/pharmacodynamic (PK/PD) indices predictive of clinical outcome of ciprofloxacin (CIP) and norfloxacin (NOR) after multiple oral dosing, and to investigate their penetration into prostatic fluid in dogs. Eight dogs received seven oral doses b.i.d. of NOR (20 mg/kg) and CIP (15 mg/kg). Drug concentrations were determined in blood and in two prostatic fluid samples. Prostatic fluid concentrations were lower than plasma concentrations for both drugs. No statistically significant differences were determined between the pharmacokinetic parameters calculated after the first and seventh doses for either CIP or NOR. The PK/PD indices were found to be useful for predicting bacteriological outcome for fluoroquinolones (area under the disposition curve/minimum inhibitory concentration [MIC] and peak plasma concentration/MIC) and indicate that with this dose regimen CIP presents a more favourable disposition than NOR for successful clinical outcome.     

Antibody-dependent mechanisms of immunity against migrating larvae of Trichinella spiralis

Normal rat peritoneal exudate cells adhere to new-born Trichinella spiralis larvae in the presence of specific antibodies produced during the course of an oral infection. After 24 hours incubation with the peritoneal cells and antibodies most of the larvae were killed. Heated immune serum had less activity. With normal serum no adherence was observed. In order to investigate the influence of antibodies on new-born larvae in vivo, larvae were pre-treated in vitro with immune serum and then inoculated intravenously into normal mice. After 30 days the yield of normal larvae was 50% of the number recovered in a control group infected with non-treated new-born larvae.