Search results for "hair"
showing 10 items of 348 documents
Contemporary Ergonomics and Business 2011: Proceedings of the 1st International Scientific-Practical Conference of the Latvian Ergonomics Society (7 …
2011
All published papers are peer-reviewed.
A comparison of 3 H-cocaine binding on melanin granules and human hair in vitro
1997
The in vitro experiments on the interaction of 3H-cocaine and melanin from Sepia officinalis confirmed the existence of drug binding sites on melanin granules. The results suggested that the binding of 3H-cocaine to melanin could be analyzed by assuming that the binding to the surface of pigment granules is analogous to the adsorption of a drug on a solid and follows Langmuir adsorption isotherm type I. Scatchard analysis indicated heterogeneity of binding sites. Structural and chemical alterations caused by isolation of the melanoproteins, which are heterogeneous in nature and show different physico-chemical properties, are considered to be most crucial. The studies on hair samples confirm…
Live imaging of stem cell and progeny behaviour in physiological hair-follicle regeneration
2012
Tissue development and regeneration depend on cell-cell interactions and signals that target stem cells and their immediate progeny. However, the cellular behaviours that lead to a properly regenerated tissue are not well understood. Using a new, non-invasive, intravital two-photon imaging approach we study physiological hair-follicle regeneration over time in live mice. By these means we have monitored the behaviour of epithelial stem cells and their progeny during physiological hair regeneration and addressed how the mesenchyme influences their behaviour. Consistent with earlier studies, stem cells are quiescent during the initial stages of hair regeneration, whereas the progeny are more …
Can we consider a natural environment always of high quality and adequate to protect population from potential risks of health threats?
2013
The question posed in the title arise because the current knowledge suggests that there are important, both beneficial and adverse, relationships between natural environment and human health. The human body obtains metals and metalloids from diet, some of which are derived from local foodstuffs and municipal water supplies, and it is therefore plausible that areas characterized by various types of bedrock and superficial materials, upon which food is grown and water drained, provide different availabilities of trace elements. The present study aimed at elucidating whether the degree of human exposure to trace elements is subject to changes in local environmental factors. This hypothesis was…
Influence of industrial activity on metal and metalloid contents in scalp hair of adolescents
2015
Petrochemical industries represent a controversial although important economical resource. They offer a great deal of job opportunities producing also a development of several areas. However, such kind of industrial plants are responsible for the change of the environmental background through the emission of toxic pollutants such as metalsmetalloids and organic compounds. People living in cities close to such industrial plants are particularly exposed to a severe environmental decline, which implies the deterioration of the quality of air, soil, water and food with the consequent human health concerns. The municipalities of Gela (GL) and Pace del Mela (PM), located respectively along the Me…
(A)sexual reproduction - a review of life cycles of grape phylloxera,Daktulosphaira vitifoliae
2009
Since its emergence as a pest of grapevine about 150 years ago, studies on the life cycle and mode of reproduction of grape phylloxera (Daktulosphaira vitifoliae Fitch) (Homoptera: Phylloxeridae) have been of considerable scientific interest and importance for applied viticulture. The life cycle of grape phylloxera, as described in the mid to late nineteenth century, is still subject to discussion and confusion. In this article, we aim to provide for the first time an overview of the reported life cycle strategies of grape phylloxera by summarizing documented observations, the results of controlled field and laboratory assays, and the results of molecular genetic analyses. Thus, we present …
A theoretical basis for the high-frequency performance of the outer hair cell’s receptor potential
1997
The frequency response of the outer hair cell (OHC) was studied theoretically. An electrical model of the OHC was analyzed mathematically, taking into account the effect of its inherent voltage-dependent capacitance. It was found that the variations of the capacitance dependent on the membrane potential could enhance the high-frequency response of the OHC, so that its cutoff frequency could be extended into the audio range. It was found further that the enhancement of the frequency response of the OHC was strongly dependent on its resting potential and on the ratio of the maximum voltage-dependent capacitance to the membrane linear capacitance.
Charge Pair Interactions in Transmembrane Helices and Turn Propensity of the Connecting Sequence Promote Helical Hairpin Insertion
2013
alpha-Helical hairpins, consisting of a pair of closely spaced transmembrane (TM) helices that are connected by a short interfacial turn, are the simplest structural motifs found in multi-spanning membrane proteins. In naturally occurring hairpins, the presence of polar residues is common and predicted to complicate membrane insertion. We postulate that the pre-packing process offsets any energetic cost of allocating polar and charged residues within the hydrophobic environment of biological membranes. Consistent with this idea, we provide here experimental evidence demonstrating that helical hairpin insertion into biological membranes can be driven by electrostatic interactions between clo…
Autonomous molecularly crowded confinement in inkjet printed femtoliter-scale aqueous compartments
2019
Natural evolution has chosen the localization of biomolecular processes into crowded sub-cellular femtoliter (fL) scale compartments for organizing complex biological processes. [1] Many synthetic biology platforms with life-like activities have been able to mimic these systems under different compartment sizes regimes. [2] However, the fabrication of crowded compartments down to sub-cellular scales is challenging, mainly because of high surface-volume ratio of these systems, finally compromising the stability of the encapsulated biomolecules. In this regard, we here bridge this gap by showing the possibility to produce femtoliter-scale aqueous droplets using a novel inkjet printing approac…
New Alkaloids of the Sarpagine Group from Rauvolfia serpentina Hairy Root Culture
2002
Three new monoterpenoid indole alkaloids, 19(S),20(R)-dihydroperaksine (1), 19(S),20(R)-dihydroperaksine-17-al (2), and 10-hydroxy-19(S),20(R)-dihydroperaksine (3), along with 16 known alkaloids 4-19 were isolated from hairy root culture of Rauvolfia serpentina, and their structures were elucidated by 1D and 2D NMR analyses. Taking into account the stereochemistry of the new alkaloids and results of preliminary enzymatical studies, the putative biosynthetical relationships between the novel alkaloids are discussed.