Application of photopolymer to core‐hair type microgels with various hair length

The new microgels, called “core‐hair” type microgels, were synthesized. They have a hair moiety consisting of the oxyhexano‐1,7‐diyl (? O? (CH₂)₅? C(O)? ) group as a spacer and the acryloyl group for polymerization. The hair length depends on the number of spacer units, and affects the viscosity and the thixotropy index of the microgel. These core‐hair microgels show the pseudo‐plastic flow of a non‐Newtonian fluid with moderate to high dispersibility in water or alcoholic solvents. Due ­to their viscosities and dispersibilities, these core‐hair microgels are useful for photopolymer, e.g. for screen printing. Therefore, these microgels were actually applied to screen printing and confirmed pattern forming on a screen printing plate through water development. We now discuss the relation between the viscosity, the dispersibility, the photosensitivity, and the rate of photopolymerization to the hair length of the microgel. Copyright © 2001 John Wiley & Sons, Ltd.     

Chromone derivatives which bind to human hair

Chromone derivatives bearing a quaternary ammonium functionality which bind to human hair were synthesised. The radical scavenging activity, according to the DPPH assay, of the chromone derivatives is considerably lower compared with flavonoids. The compounds show interesting UV absorption properties that depend on the position of a methoxy substituent. A bathochromic shift of 29 nm was observed when the methoxy group on the ammonium salts were shifted from position 7 to position 6.     

A different approach to hair analysis: Application to multiple sclerosis

The results connected with the preparations of uranium and plutonium Standard Reference Materials, in which the content of the main compound is certified are considered.     

Sulphur isotopes in animal hair track distance to sea

Stable sulphur isotope ratios (³⁴S/³²S) in animal tissues have been suggested as a tracer of coastal residency of terrestrial animals, but data are lacking that quantify the inland range of the sulphur coastal signal and the effects of seasonality. Here, we present δ³⁴S measurements of sheep wool collected seasonally on eight farms across Ireland and wool samples collected opportunistically along the west and east coasts. We observed large (>10‰) δ³⁴S differences across the island and we show that wool δ³⁴S values were negatively correlated with distance to the west coast. We propose that this is due to the predominantly (south‐)westerly airflow, possibly combined with the influence of anthropogenic sulphur deposited from the east. While essentially all the sulphur contained in west‐coast wool is of marine origin, relatively high δ³⁴S values were still measured >100 km inland, suggesting that marine sulphur can be carried over long distances. Seasonal variations are small at the individual level for sedentary grazing animals. We conclude that sulphur isotopes ratios measured in archival keratinous tissues can be used to describe regional δ³⁴S isoscapes primarily defined by distance to coasts and thus provide a tool to detect short‐term movements of domestic, feral and wild animals within such isoscapes. Copyright © 2011 John Wiley & Sons, Ltd.     

The tail of mycolic acids

The FabH enzyme from M. tuberculosis binds the acyl tail of large substrates at the end of a buried hydrophobic tunnel. Sachdeva et al. (2008) use reactive chemical probes and X-ray crystallography to show that substrates can bind to an open state of FabH without threading through the tunnel.     

Improved STR typing of telogen hair root and hair shaft DNA

Today the STR typing of telogen hair and hair shafts is regarded as a challenge. The small DNA quantity in the hair is highly degraded. Another problem are PCR inhibitors in the hair. In particular hair pigments, the melanins, are known to inhibit PCR. Hairs are exposed to sunlight and partly to chemical oxidation processes, which make them even more difficult to analyze. To increase the chances of a correct typing of hair, the small amount of DNA must be successfully isolated and the inhibitors have to be removed or neutralized. Furthermore, miniSTR typing improves the analysis of stains with degraded DNA like it is the case with hair. We introduce a nonorganic extraction method and in addition a miniSTR concept which is promising in typing stains with little and degraded DNA, especially hairs. The miniSTR concept including five database STRs (SE33, VWA, TH01, FGA, D3S1358) and the gender typing system Amelogenin was optimized for the amplification of hair DNA. Compared to commercial STR kits, this approach resulted in considerably higher success rates.     

What contribution can be made to biological monitoring by hair analysis

Summary The specific problems of sampling and sample preparation are presented here. The interpretation of sample comminution is discussed, the difficulties of the interpretation of hair analysis are pointed out, ending with consideration of the information available from hair analysis as opposed to that from the analysis of other types of sample and where its limits lie. The application and relevance of hair analysis in industrial medicine today is illustrated and discussed on the basis of several examples from clinical chemistry.Based on a lecture delivered to the working circle Analysen in biologischem Material — Deutsche Forschungsgemeinschaft Bonn, in Giessen, 16. October 1989     

Scalp hair as a monitor of population exposure to environmental pollutants

Concentrations of As, Cd, Hg, Pb, Sb and Zn have been measured in hair from population groups with varied types of environmental exposure. Rural and urban controls have exhibited low levels of most toxic elements, whereas people residing near urban lead refineries, rural gold refinery and other industries have shown high elemental concentrations in their hair. A combination of instrumental as well as radiochemical neutron and photon activation analysis methods have been used to determine the concentrations of the above elements. The precision and accuracy of these methods have been evaluated.     

Influence of the stage of the hair cycle on Cd deposition in hair

Shortly after a single injection of Cd a much higher deposition of Cd was observed in growing hair (anaphase) than in resting hair (telophase). Shifting the time of the administration between 7 d before the onset of matrix production and full hair growth did not appreciably alter the initial deposition in spite of the rapid decline of Cd in blood plasma between the injection and the start of hair growth. After the initial deposition the concentration decreased in growing as well as in resting hair. In growing hair this is attributed to the addition of new matrix containing less Cd due to its declining supply via blood. In the resting hair it may reflect the decline of Cd in the follicular tissue adhering to the hair roots. The study demonstrates that the deposition of internal Cd in hair occurs mainly in those sections of hair growing at the time of the actual intake of Cd into the organism. The quantity of Cd found in a particular section of hair in the absence of external contamination, therefore, indicates first and foremost the quantity of Cd taken up into the blood stream—after ingestion or inhalation—at the time of the actual formation of this section notwithstanding the actual body burden at that time. This work was done under a contract of the International Atomic Energy Agency, Vienna.     

What contribution can be made to biological monitoring by hair analysis?

Summary Over the last decades there have been problems in hair analysis which have been the subject of great controversy. Great expectations were aroused for the results of hair analysis and new arguments were put forward to counter them. This meant that a method, which was applicable with certain reservations, was discredited over a long period.This publication attempts to describe the most important factors which can affect the analysis of trace elements in human hair. Analytical methods must take in account the development and morphology of human hair and the selective bonding of trace elements on the components of the hair.This involves a great deal of extra experimental complication which increases the costs considerably. However, economics should play a subsidiary role in the search for truth by chemical analysis.Based on a lecture delivered to the working circle Analysen in biologischem Material — Deutsche Forschungsgemeinschaft, Bonn, 8. December 1988     

Thermal analysis of hair treated with oxidative hair dye under influence of conditioners agents

This research aimed the effect on Caucasian hair tresses treated with oxidative hair dye, either incorporated or not with conditioners agents, analyzed by Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TG). The formulations of hair dyes were emulsions oil-in-water with light blond color containing or not the conditioners agents: silanetriol and panthenol; PEG-12 dimethicone; hydrolyzed silk, hydrolyzed milk protein, and lactose. Each dye (1.5 g) was applied in the hair tress (2.0 g/20.0 cm of length of Caucasian light-brown), previously treated, more 1.5 g of hydrogen peroxide 20 vol during 40 min. Evaluation of mass loss of the different hair sample demonstrates that these chemical hair treatments impair the hair fibers, reduced their moisture content with respect to the untreated hair. The incorporation of conditioners agents (silanetriol and panthenol; PEG-12 dimethicone; hydrolyzed silk, hydrolyzed milk protein, and lactose) in oxidative hair dyes types did not decrease the damage caused on the tresses by the coloring process quantified by TG/DTG. However, the DSC curves demonstrated those conditioners agents (silanetriol and panthenol; PEG-12 dimethicone) dislocated the beginning of the third event in 20 °C and they inhibited the presence of the fourth event, having characterized thermal protection to the hair.     

Photo yellowing of human hair

In general, human hair is claimed to turn yellower after sun exposure. This is particularly affirmed for white hair. However, quantitative data relating yellowness to hair type and to the radiation wavelength are missing. This work shows results of the effect of full or UVB-filtered radiation of a mercury vapor or a xenon-arc lamp on the yellowness of virgin white, dark-brown, blond and red hair. All hair types showed a substantial change in yellowness after irradiation, which is dependent on the hair type and radiation wavelength. Surprisingly, white hair turns less yellow after both full and UVB-filtered radiation exposure. This effect is more pronounced when UVB is filtered from the radiation system. The only radiation that shows a photo-yellowing effect on white hair is infrared. As the yellowness of white hair is commonly related to tryptophan degradation, fluorescence experiments with hair solutions were performed to identify the natural degradation of tryptophan which occurs in hair after light irradiation. Pigmented hairs were also studied, as well as hair treated with a bleaching solution. Although we observe a decrease in tryptophan content of hair after lamp radiation, a direct correlation with hair yellowness was not achieved. Results are discussed in terms of hair type, composition and melanin content.     

Analytical pitfalls in hair testing

This review focuses on possible pitfalls in hair testing procedures. Knowledge of such pitfalls is useful when developing and validating methods, since it can be used to avoid wrong results as well as wrong interpretations of correct results. In recent years, remarkable advances in sensitive and specific analytical techniques have enabled the analysis of drugs in alternative biological specimens such as hair. Modern analytical procedures for the determination of drugs in hair specimens—mainly by gas chromatography–mass spectrometry (GC–MS) and liquid chromatography–mass spectrometry (LC–MS)—are reviewed and critically discussed. Many tables containing information related to this topic are provided.     

Arsenic speciation in hair extracts

Ingested arsenic is known to be not only excreted by urine, but to be stored in sulphydryl-rich tissue like hair, nail or skin. We developed an extraction method for arsenic species from these tissues and studied the stability of different arsenic species during the extraction process. Inorganic and pentavalent methylated arsenic was found to be stable under the extraction conditions, whereas trivalent methylated arsenicals and the thio-analogue of DMA^V (DMAS) showed reduced stability. The absorption ability of hair for these different species was studied as well. Inorganic arsenic is better absorbed by hair than monomethyl- or dimethyl-arsenicals, whereby the trivalent forms are taken up better than the pentavalent forms. Independent of which methylated arsenical was used for the incubation, the pentavalent form was always the dominant form after extraction. Hair and nail samples from humans suffering from chronic arsenic intoxication contained dominantly inorganic arsenic with small and strongly varying amounts of DMA^V and MA^V present. DMAS was only found in some nail sample extracts containing unusually high amounts of DMA^V and is believed to be formed during the extraction process.     

Contribution to the sample preparation in the radionuclide X-ray fluorescence analysis of hair

Methods of sample treatment in XRF analysis of hair are studied in view of the effect on analytical results. A new method is proposed based on the incomplete ashing of hair followed by pellet preparation. Its suitability is estimated on the XRF analysis of real hair samples collected from 4 healthy adults.