Assessment of Qualitative and Quantitative Data from Pathological Hairs – A Critical Evaluation of Scanning Electron Microscope and Proton Induced X-Ray Emission Analyses

Analysis of single hair fibres in genetic disorders is a desirable complement to the clinical diagnosis. The scanning electron microscope (SEM) allows detailed study of the surface morphology of hair fibres which may explain some mechanical characteristics of the pathological hair. Quantitative elemental data may indicate biochemical or metabolic abnormalities. In this preliminary study we assess the feasibility of combining SEM and proton induced X-ray emission (PIXE) analysis on single hair fibres from 12 cases of genetic disease influencing the integument status. We conclude that SEM is a valuable tool in the analysis of hair pathology. The macro-PIXE technique involves some methodological and technical problems which in many cases are likely to be solved by using a proton microbeam. However, this means that routine methods have to be abandoned and careful selection of the material for analysis is an imperative necessity

Proton Induced X-Ray Emission Analysis of Biological Specimens - Past and Future

Proton induced X-ray emission (PIXE) analysis is a comparatively new member of the family of spectrographic methods. In the last decade PIXE techniques have been applied to biological problems with great success. This review gives a condensed presentation of recent developments in biological (medical, zoological, and botanical) applications of PIXE analysis with special focus on factors which commonly influence the results, such as calibration, contamination, and preparation. The great advantage of PIXE analysis in studying physiologically important trace elements such as Zn, Mg, Fe, and Cu is underlined. Elemental mapping not only allows quantitative elemental analysis, but can also demonstrate the important differences in the morphological distributions of elements by comparing normal and pathological tissue

Elemental Content of Anagen Hairs in a Normal Caucasian Population Studies with Proton Induced X-Ray Emission (PIXE)

The elemental content of anagen hair fibers in a Caucasian population of healthy females and males in the age range 10-69 years was performed to constitute a baseline for further studies of pathological conditions. Proton induced X-ray emission (PIXE) analyses were performed on single hair fibers in triplicates from 103 individuals in order to determine sulfur, zinc, calcium, and chlorine content. The hair fibers were all anagen hairs collected from a site little influenced by genetic and hormonal influences 1.5 cm above the right ear of the probands. An area 5-8 mm from the follicle bottom was chosen for minimize effect the of analysis in all cases hair-do contamination. The average sulfur content was 0.049 g/g and the average zinc content 170 μg/g. These results were not significantly influenced by chloroform/ethanol rinsing before analysis. The calcium and chlorine contents were 330 μg/g and 0.0033 g/g respectively. The latter data are expected to be more seriously influenced by external factors (e.g., contamination) than sulfur and zinc. No correlation between elemental concentration and sex was found for sulfur and zinc in the present material. PIXE analysis of single hair fibers yields valuable information on the elemental composition of hair fibers and can be rapidly and efficiently performed after simple mounting procedures

Catches of bloodsucking blackflies (Diptera: Simuliidae) tell different stories depending on sampling method

To compare different sampling techniques, blackflies were captured along six Swedish rivers in 2001 and 2002, using two fundamentally different methods: (1) daytime trapping with a vehicle-mounted net, and (2) exposure of CO 2 -baited traps. The methods were selectively different for different species of blackflies. Some species were caught relatively more frequently by vehicle trapping and others by CO 2 trapping. Only rarely were species catches proportionally similar between the two methods. We suggest that the different catch success reflects differences in host-searching behaviour in the species present and that the sampling methods are complementary

Reproductive performance of dairy cows from parturition to conception

International audienc

Human Skin Physiology Studied by Particle Probe Microanalysis

Particle probe methods (electron probe and proton probe X-ray microanalysis) have been applied to investigate the distribution of elements and water over the different layers of the epidermis. For major elements, electron probe X-ray microanalysis (XRMA) provides the advantage of superior spatial resolution, but for trace element analysis the more sensitive proton probe (particle induced X-ray emission, PIXE) analysis has to be used. On a dry weight basis, the concentration of S is rather constant across the epidermis, whereas the concentrations of P, K, Cl and Na show gradients with high levels in stratum germinativum (basale) and stratum spinosum but low levels in the stratum granulosum and stratum corneum. Essentially, Fe and Zn are confined to the basal region in normal skin. The concentration of Ca, however, increased steadily from the basal region to the stratum corneum. The probe technique allows quantitative analysis of stratum-specific changes in elemental content in a variety of pathological conditions, e.g., changes induced by nickel, detergents and other chemicals, or in psoriatic skin. Of particular interest are findings of increased Fe and Zn in non-involved psoriatic skin. Since the different layers of the skin have different elemental concentrations and react differently under pathological conditions, the probe techniques are far superior to bulk chemical analysis in elucidating physiological and pathological processes in the skin

The impacts of increasing current velocity on the drift of Simulium monticola (Diptera: Simuliidae): a laboratory approach

Current velocity and associated physical forces are among the most important factors shaping lotic benthic communities. The recent increase in the frequency and intensity of flow alterations, especially related to hydroelectric use or irrigation, represents a key element of riverine environment deterioration. Numerous studies have investigated the effect of current velocity increases on macrobenthic fauna, underlining that, in most cases, these increases enhance the drift, i.e. the abandonment of the substrate by macroinvertebrates. The purpose of this study is to examine the drift propensity of Simulium monticola (Diptera: Simuliidae) under different water velocities. Simuliidae are one of the most characteristic components of fast-flowing environments in rivers. Experiments were conducted in an artificial stream in the laboratories of Politecnico di Torino, analysing the drift of organisms at different current velocities. The observed variability of drift appears to be related to velocity increases: interestingly, we evidenced an inverse relationship between velocity and drift propensity, with low amounts of drifting organisms at higher velocities. This tendency was not related to the size of Simuliidae larvae: when comparing the size of drifting organisms with velocity, no significant correlations were detected. We hypothesized that the tendency to drift was mainly behavioural rather than catastrophic, and related to the preference for high water velocities. Our findings support the hypothesis that increases in water velocity can cause complex changes in the drift of the macrobenthic community, increasing the propensity for some species to leave the substrate and decreasing it for other

A theoretical study of the 1B2u and 1B1u vibronic bands in benzene

The two lowest bands, 1B2u and 1B1u, of the electronic spectrum of the benzene molecule have been studied theoretically using a new method to compute vibronic excitation energies and intensities. The complete active space (CAS) self-contained field (SCF) method (with six active π-orbitals) was used to compute harmonic force field for the ground state and the 1B2u and 1B1u electronic states. A linear approximation has been used for the transition dipole as a function of the nuclear displacement coordinates. Derivatives of the transition dipole were computed using a variant of the CASSCF state interaction method. Multiconfigurational second-order perturbation theory (CASPT2) was used to obtain absolute excitation energies (12 active π-orbitals). The results show that the approach works well. Vibrational progressions are well described in both bands and intensities, and energies are in agreement with experiment, in particular when CASPT2 derived geometries are used. One interesting result is that computed vertical energies fall about 0.1 eV on the high energy side of the band [email protected]