Assessment of X-ray fluorescence capabilities for nail and hair matrices through zinc measurement in keratin reference materials

BackgroundNovel and emerging biomarkers of zinc status are being developed to help study and address zinc deficiency around the world. Two potential biomarkers, nail and hair, involve the measurement of zinc from easily accessible keratin-based components of the body. Portable X-ray fluorescence (XRF) is a relatively new approach to the assessment of zinc in nail or hair, and has a number of compelling advantages compared with other techniques. The aim of the current study was to test the ability of XRF to measure zinc in keratinized reference materials (RMs) designed to simulate nail and hair.MethodsFour Keratin Matrix RMs were prepared and characterized for numerous trace elements by the New York State Department of Health’s Wadsworth Center. The Keratin Matrix RMs consisted of powdered samples of caprine (goat) horns pooled from several animals. Concentrations of zinc, as assessed by inductively coupled plasma mass spectrometry (ICP-MS), were similar to what would be expected from human nail or hair tissues. Repeat measurements of the RMs were made using a portable XRF system. The XRF zinc results were compared with the ICP-MS zinc concentrations. Three different approaches to quantifying the zinc content by XRF were performed: (1) zinc signal to total signal ratio, (2) zinc signal to sulfur signal ratio, and (3) system output zinc concentration.ResultsThe portable XRF results from a given RM were found to be consistent across repeat trials under all three approaches to XRF quantitation. Precision, calculated as the relative standard deviation of repeat measurements ranged from an average result of 0.8 % (using the system output zinc concentration method) to 6.1 % (using the zinc signal to sulfur signal ratio method). Measurement of the RMs provided XRF zinc results which scaled well with ICP-MS zinc concentration, particularly when using the XRF zinc to total and system zinc concentration methods. A Bland-Altman plot showed that the XRF system zinc concentration output exceeded the ICP-MS zinc concentration by, on average, 10.2 % ± 1.2 %.ConclusionOverall, both accuracy and precision of measurement were found to be promising for portable XRF, provided appropriate conversions to concentration are introduced. The results of this study indicate that portable XRF is an effective and dependable method of assessing zinc concentration in keratinized tissue RMs. This will have implications for the future use of portable XRF to monitor zinc status in humans through measurements of nail and hair.     

Contacts of pore tubules and sensory dendrites in antennal chemosensilla of a silkmoth: Demonstration of a possible pathway for olfactory molecules

Antennal olfactory hairs of Antheraea polyphemus were investigated by means of transmission electron microscopy. Adequate preservation of dendrites and extracellular pore tubules is obtained by mechanical opening of the hair lumen and subsequent chemical fixation. The dendritic membrane has a cell coat. The dendrites contain microfilamentous structures in addition to their cytoplasmatic microtubules. The extracellular pore tubules traverse the hair cuticle and reach into the hair lumen for maximally 350 nm. Their diameter varies between 20 and 40 nm, depending on the preparation method. They consist of an electron-dense wall and an electron-lucent core. The wall has a helical substructure and is covered with a fuzzy coat. Contacts of pore tubules and dendritic membranes occur wherever dendrites are near the inner surface of the hair cuticle. Some of the pore tubules terminate approximately at right angles on the dendritic membrane, others lie against the membrane. The contact seems to be made via the surface coats of the tubules and the membrane. The structure of pore tubules which had been negatively stained with uranyl acetate is similar to the conventionally thin-sectioned material. The observations provide support for earlier assumptions that pore tubules are the pathways by which odor molecules reach the dendritic membrane.     

Differential responses of galeal gustatory sensilla of the adult Colorado potato beetle, Leptinotarsa decemlineata (Say), to leaf saps from host and non-host plants

ABSTRACT Responses of galeal sensilla of the Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), to leaf sap from Solanum tuberosum and a number of other solanaceous and non-solanaceous plants are described. A single cell responds vigorously to expressed sap from S.tuberosum , -and even to ten-fold dilutions of expressed sap. The response is characterized by a high spike frequency, low phasic activity and a tonic phase which can last for tens of seconds. At 8 s following stimulus application the primary response is typically 50% of its original activity, indicating slow adaptation to the sap stimulus. The primary response varies little among multiple stimulations of single sensilla and among sensilla on the same animal. There is a secondary response to potato leaf sap from one or more cells which have low spike amplitudes. This is usually of much lower frequency than the response from the primary cell, and it is highly variable.
The prominent and reproducible single cell response to potato sap may be an important component in signalling the presence of a host plant. This hypothesis is tested using saps from two other species of Solanum which are hosts, and several solanaceous and non-solanaceous non-hosts. Responses of galeal sensilla to the three host-plants tested were qualitatively similar and reproducible while responses to the non-hosts were highly variable and qualitatively different from responses to host saps. These results are interpreted and discussed in the context of a possible mechanism for chemosensory coding of complex stimuli in the insect/plant relationship.
Analysis of the raw electrophysiological data required extensive use of a microcomputer and several programs were developed during the course of this study. The computer analyses are briefly described in the paper and additional information and copies of the programs are available from the authors.     

Olfactory responses recorded from sensilla coeloconica of the silkmoth Bombyx mori

Abstract. Extracellular single sensillum recordings were made from the double-walled multiporous sensilla coeloconica on the antennae of males and females of Bombyx mori L. (Lepidoptera: Bombycidae). The receptor neurones responded to olfactory stimuli; no thermo- or hygroreceptors were found. Many neurones responded with a decrease of the transepithelial potential and increased rates of nerve impulses to aliphatic hydrocarbons with chain lengths between three and ten carbon atoms. Most abundant were neurones responding best to acids and aldehydes. Receptor neurones responding with a low threshold to only one acid of a certain chain length were considered as specialists. In some sensilla an increase of the transepithelial potential combined with nerve impulse inhibition was observed in response to monoterpene alcohols. Neurones responding with excitation to aliphatic acids and with inhibition to terpenes were found in the same sensilla. Some neurones excited by aliphatic acids were inhibited by terpenes. Responses to headspace volatiles of mulberry leaves, the larval food, were also obtained. Therefore the coeloconic sensilla may be involved in the selection of oviposition sites.     

Red meat and fruit intake is prognostic among patients with localized cutaneous melanomas more than 1 mm thick

BackgroundAs the 10-year mortality for localized cutaneous melanoma more than 1.00 mm thick approaches 40% following complete resection, non-therapeutic interventions that can supplement recommended active surveillance are needed. Although guidelines recommending nutrition, physical activity and tobacco cessation for cancer survivors have been published, data describing their associations with melanoma survivorship are lacking.MethodsAnalysis of modifiable lifestyle behaviors collected on the 249 cases with melanomas more than 1.00 mm thick enrolled in the Connecticut Case–Control Study of Skin Self-Examination study was conducted. Independent associations with melanoma-specific survival were evaluated through Cox proportional hazards modeling adjusting for age, gender, Breslow thickness, ulceration and the presence of microsatellites. Independently significant variables were then combined into a single model and backwards elimination was employed until all remaining variables were significant at p < 0.05.ResultsFollowing adjustment for age, Breslow thickness and anatomic site of the index melanoma, daily fruit consumption was associated with improved melanoma-specific survival (HR = 0.54; 95% CI: 0.34–0.86) whereas at least weekly red meat consumption was associated with worse outcomes (HR = 1.84; 95% CI: 1.02–3.30). Natural red (HR = 0.44; 95% CI: 0.22–0.88) or blond (HR = 0.52; 95% CI: 0.29–0.94) hair were also favorably prognostic. Higher fish consumption was of borderline significance for improved survival only when considered independently (HR = 0.65; 95% CI: 0.40–1.05); no association was seen following adjustment for red meat and fruit consumption (p > 0.10).ConclusionsDietary choices at the time of diagnosis are associated with melanoma-specific survival in patients with melanomas more than 1.00 mm thick. Further validation of our findings in larger cohorts with repeated post-diagnostic measures is warranted to further evaluate whether dietary modification during the survivorship period can improve melanoma-specific survival.     

Antennal olfactory sensory neurones responsive to host and nonhost plant volatiles in gorse pod moth Cydia succedana

We investigate the response profiles of the antennal olfactory sensory neurones (OSNs) in male and female gorse pod moth Cydia succedana to host and nonhost volatiles, using the single sensillum recording technique. Eight different classes of olfactory sensilla are identified in female C. succedana and five different classes of olfactory sensilla in males. Nineteen different classes of OSNs are identified from the sensilla in females, and nine different classes of OSNs in the male sensilla. All classes of sensilla, except class F7 and class M1 sensilla, co‐compartmentalize two or three OSNs in each sensillum, and the OSNs present in the same sensillum are specialized for different volatiles. Most plant‐volatile OSNs exhibit phasic‐tonic type of temporal responses, whereas the pheromone OSNs in male C. succedana show rather phasic responses. The majority of OSNs identified in C. succedana display highly specialized responses to a narrow range of volatiles, whereas only a small proportion of OSNs show broad response spectra. Two most abundant classes of OSNs exhibit highly specialized responses to β‐myrcene and (E)‐β‐ocimene, two major volatiles released by gorse (Ulex europaeus), the main host of C. succedana. By contrast, several other classes of OSNs exhibit highly specialized responses to geraniol, (Z)‐3‐hexen‐1‐ol, (±)‐α‐terpineol, citral and benzyl acetate, which are produced by various nonhost plants. Taking the results of the present study together, we suggest that C. succedana use the combinational input from a set of highly specialized OSNs for host plant volatiles and another set of highly specialized OSNs for nonhost volatiles to discriminate between hosts and nonhosts.     

Surface coats of pore tubules and olfactory sensory dendrites of a silkmoth revealed by cationic markers

Negatively charged surface coats have been demonstrated on the pore tubules and dendritic membranes of olfactory hairs of male Antheraea polyphemus silkmoths by application of the cationic markers lanthanum (La3+), ruthenium red (RR), and cationized ferritin (CF). Lanthanum and RR diffused readily into the apically opened hairs, whereas CF penetrated only for a relatively short distance. Deposits of the markers are distributed as follows: the inner surfaces of the hair walls are stained by RR and to a small degree by CF; the surfaces of the pore tubules and the dendritic membranes are stained by all three markers. The pore tubules have the strongest affinity for CF. The number of pore tubule-membrane contacts seems to be increased by the cationic dyes. The dendrites are often penetrated by RR, which forms deposits on the inner membrane leaflets, the cytoplasmic microtubules, and microfilaments, and by La3+, but never by CF. The observations provide support for the assumption that, first, the pore tubule-membrane contacts are formed via surface coats of both structures, possibly influenced by cations and, second, that the dendrites remain intact after pinching off the hair tips.     

Electrophysiological and behavioural responses to lactic acid stimuli in larvae of Tenebrio molitor L. (Coleoptera: Tenebrionidae) and permeability of antennal sensilla

Abstract. Of the five types of antennal sensilla in larvae of Tenebrio molitor L., only the uniporous long pointed pegs and papillate plates are readily permeable to an aqueous solution of CoCl₂, which is generally indicative of a gustatory function. An electrophysiological investigation confirms the gustatory role of the papillate sensilla on the antenna, and it suggests that they are responsible for mediating the behaviour of larvae toward lactic acid stimuli. Larvae with ablated antennae do not aggregate as would normal animals in the presence of lactic acid stimuli. The uniporous long pointed pegs show no response to lactic acid or other aqueous stimuli.