Acute impairment of the sensitivity of skin mechanoreceptive units caused by vibration exposure of the hand

The thresholds of single mechanoreceptive afferent units, innervating the glabrous skin of the human hand to sinusoidal skin indentations at 2, 20 or 200 Hz were measured before and after 2 min powerful vibration exposures at the same frequencies. The corresponding psychophysical thresholds were measured in collateral experiments while still monitoring the unit responses. An acute but temporary rise in threshold occurred as a consequence of the vibration exposure in three different unit types (FA I, FA II and SA I). A close correlation was found between the neural and psychophysical thresholds with regard to the magnitudes of the shifts and the time courses of the recovery, provided that the thresholds were measured at the appropriate frequencies (i.e. at 200, 20 and 2 Hz while recording from FA II, FA I and SA I units, respectively). It was concluded that the acute impairment of tactile sensibility caused by vibration exposure, as earlier observed in psychophysical studies, most likely can be explained by a depression of the excitability of the mechanoreceptive afferent units.     

Pesticide exposure of non-occupationally exposed subjects compared to some occupational exposure: a French pilot study

Data about non-dietary exposure to different chemical classes of pesticides are scarce, especially in France. Our objective was to assess residential pesticide exposure of non-occupationally exposed adults, and to compare it with occupational exposure of subjects working indoors. Twenty unexposed persons, five gardeners, seven florists and nine veterinary workers living in Paris area were recruited. Nineteen residences, two greenhouses, three florist shops and three veterinary departments were then sampled. Thirty-eight insecticides, herbicides and fungicides were measured in indoor air with an air sampler for 24 h, and on hands by wiping them with isopropanol-wetted swabs. After extraction, samples were analysed by gas and high-performance liquid chromatography. Seventeen different pesticides were detected at least once in indoor air and twenty-one on the hands. An average of 4.2+/-1.7 different pesticides was detected per indoor air sample. The organochlorines lindane, alpha-endosulfan and alpha-HCH were the most frequently detected compounds, in 97%, 69% and 38% of the samples, respectively. The organophosphates dichlorvos and fenthion, the carbamate propoxur and the herbicides atrazine and alachlor were detected in more than 20% of the air samples. Indoor air concentrations were often low, but could reach 200-300 ng/m(3) in residences for atrazine and propoxur. Propoxur levels significantly differed between the air of veterinary places and other places (Kruskal-Wallis test, p<0.05) and dieldrin levels between residences and workplaces (p<0.05). There was a greater number of pesticides on hands than in air, with an average of 6.3+/-3.3 different pesticides detected per sample, the most frequently detected being malathion, lindane and trifluralin, in more than 60% of the subjects. Maximal levels (up to 1000-3000 ng/hands) were observed either in the general population or in workers, depending on the pesticide. However, no significant difference was observed between workers and general population handwipe pesticide levels. As expected, gardeners were exposed to pesticides sprayed in greenhouses. Florists and veterinary workers, whose pesticide exposure had not been described until now, were also indirectly exposed to pesticides used for former pest control operations. Overall, general population was exposed to more various pesticides and at levels sometimes higher than in occupational places. The most frequent pesticides in residences were not the same as in US studies but levels were similar. These preliminary results need to be confirmed in a greater number of residences from different parts of the country, in order to better assess pesticide exposure of the general population and its influencing factors.     

Mesenchymal stem cells,secretome and biomaterials in <i>in-vivo</i> animal models: Regenerative medicine application in cutaneous wound healing

The treatment of nonhealing and chronic cutaneous wounds still needs a clinical advancement to be effective. Both mesenchymal stem cells (MSCs), obtained from different sources, and their secretome derived thereof (especially exosomes) can activate signaling pathways related to promotion of cell migration, vascularization, collagen deposition, and inflammatory response demonstrating prohealing, angiogenetic and anti-scarring capacities. On the other hand, biodegradable biomimetic scaffolds can facilitate endogenous cell attachment and proliferation as well as extracellular matrix production. In this Review, we revise the complex composites made by biomimetic scaffolds, mainly hydrogels, and MSC-derived exosomes constructed for cutaneous wound healing. Studies demonstrate that there exists a synergistic action of scaffolds with encapsulated exosomes, displaying a sustained release profiles to facilitate longlasting healing effects. It can be envisioned that dressings made by biomimetic hydrogels and MSC-derived exosomes will be clinically applied in the near future for the effective treatment of nonhealing and chronic wounds.     

Temperature Transients: A Model for Heat Diffusion through the Skin,Thermoreceptor Response and Thermal Sensation

A model based on heat diffusion through the skin is developed for the dynamic response of cutaneous thermo-receptors to temperature stimuli at the skin surface. It is applied to various neurophysiological experiments with good results. The model is then extended to sensation and a set of psychophysical experiments on human subjects is examined and compared with the model predictions. Altogether, in terms of both the neurophysiological response and the sensation response, this model gives good agreement with the experiments.     

A gap detection tactility test for sensory deficits associated with carpal tunnel syndrome

An automated gap detection tactility test was investigated for quantifying sensory deficits associated with carpal tunnel syndrome (CTS). The test, which involved sensing a tiny gap in an otherwise smooth surface by probing with the finger, had functional resemblance to many work-related tactile activities such as detecting scratches or surface defects. Gap detection thresholds were measured using the converging staircase method of limits paradigm. Sixteen normal subjects between 21 and 66 years of age were tested for studying important factors affecting gap detection thresholds. Actively probing with the index finger had a threshold almost an order of magnitude more sensitive (mean = 0·19mm, SD = 0·llmm) than passive touch (mean =1·63mm. SD = 0·62mm), which was similar to two-point discrimination. Average thresholds decreased by 24% as contact force increased from 25 to 75?g. Performance in this tactility test quickly stabilized and showed little learning effects over the period of the test, as evidenced by the lack of significant differences between six replicates. The results were highly repeatable. No significant threshold differences were observed between test and retest trials on different days, or between dominant and non-dominant hands. A contact force of 50?g was recommended as optimal for this test since it required moderate force but resulted in a smaller threshold compared with 25 or 75?g. A companion study was conducted using eight normal subjects and ten subjects diagnosed as having CTS. Average gap detection threshold, when finger probing was allowed, was 0·20?mm (SD = 0·11?min) for the normal subjects and increased two-fold to 0·40?mm (SD = 0·19?mm) for the CTS subjects. Average gap detection threshold, when the finger probing was not allowed, was 1·71?mm (SD = 0·53mm) for the normal subjects and increased by 48% to 2·53?mm (SD = 0·87?mm) for the CTS subjects. The results suggest that people suffering from CTS may experience similar functional deficits in daily living and work activities. The small inter-subject variability makes this test a candidate for having utility as a monitoring test for loss of cutaneous tactile sensitivity.     

The contribution of virtual reality to research on sensory feedback in remote control

Here we consider research on the kinds of sensory information most effective as feedback during remote control of machines, and the role of virtual reality and telepresence in that research. We argue that full automation is a distant goal and that remote control deserves continued attention and improvement. Visual feedback to controllers has developed in various ways but autostereoscopic displays have yet to be proven. Haptic force feedback, in both real and virtual settings, has been demonstrated to offer much to the remote control environment and has led to a greater understanding of the kinesthetic and cutaneous components of haptics, and their role in multimodal processes, such as sensory capture and integration. We suggest that many displays using primarily visual feedback would benefit from the addition of haptic information but that much is yet to be learned about optimizing such displays.     

Room air temperature affects occupants’ physiology,perceptions and mental alertness

Thermal environment that causes thermal discomfort may affect office work performance. However, the mechanisms through which occupants are affected are not well understood. This study explores the plausible mechanism linking room air temperature and mental alertness through perceptual and physiological responses in the tropics. Ninety-six young adults participated as voluntary subjects in a series of experiment conducted in the simulated office settings. Three room air temperatures, i.e. 20.0, 23.0 and 26.0 °C were selected as the experimental conditions. Both thermal comfort and thermal sensation changed significantly with time under all exposures (P < 0.0001). Longer exposure at 20.0 °C led to cooling sensations due to lower skin temperatures (P < 0.0001) and was perceived as the least comfortable. Nevertheless, this moderate cold exposure induced nervous system activation as demonstrated by the increase of α-Amylase level (P < 0.0001) and the Tsai–partington test (P < 0.0001). A mechanism linking thermal environment, occupants' responses and performance is proposed.     

Memetic improved cuckoo search algorithm for automatic B-spline border approximation of cutaneous melanoma from macroscopic medical images

This work follows up a previous paper at conference Cyberworlds 2018 for automatic border approximation of cutaneous melanoma and other skin lesions from macroscopic medical images. Given a set of feature points on the boundary of the skin lesion obtained by a dermatologist, we introduce a new method for automatic least-squares B-spline curve fitting of such feature points. The method is based on the original cuckoo search algorithm used in the conference paper but with three major modifications: (1) we use an enhanced version of the algorithm in which the parameters change dynamically with the generations; (2) this improved method is coupled with the Luus-Jaakola local search heuristics for better performance; (3) the original Bézier curves are now replaced by the more powerful and more general B-spline curves, providing extra flexibility and lower polynomial degree. The new method (called memetic improved cuckoo search algorithm) has been applied to a benchmark comprised of ten medical images of skin lesions. The computer results show that it performs very well and yields a border curve enclosing the lesion and fitting the feature points with good accuracy. Furthermore, a comparison with ten alternative methods in the literature (six standard mathematical methods for B-spline fitting, two state-of-the art methods in medical imaging, the method in our conference paper and the non-memetic version of our new method) shows that it outperforms all these methods in terms of numerical accuracy for the instances in our reference benchmark.     

Improved drug loading via spray drying of a chalcone implant for local treatment of cutaneous leishmaniasis

Current chemotherapy of cutaneous leishmaniasis (CL), even the mildest forms, encompasses multiple and painful injections with toxic drugs that cause systemic adverse effects. Recently, we showed the promising use of poly(lactic-co-glycolic acid) (PLGA) microparticles loaded with an antileishmanial nitrosylated chalcone (CH8) for effective, safe, local, and single-dose treatment of CL. Here, we proposed to optimize the delivery system by increasing the CH8 loading in PLGA-microparticles using spray drying instead of emulsification-solvent evaporation. The effect of solvent composition and polymeric matrix changes on thermal properties, loading efficiency, particle size, morphology, and spatial drug distribution of the CH8-loaded microparticles was evaluated. The results showed that spray drying allowed a higher CH8 content (18% w/w), as contrasting with the previous solvent evaporation technique that maximally incorporated 7.8% of CH8. In vitro studies on 96-hour incubation with L. amazonensis-infected macrophages showed that entrapment in spray-dried PLGA microparticles rendered CH8 safer, preserved its antileishmanial activity, and did not affect its antioxidant properties.     

A spatially explicit agent-based modeling approach for the spread of Cutaneous Leishmaniasis disease in central Iran,Isfahan

Cutaneous Leishmaniasis (CL) is an endemic vector-borne disease in the Middle East and a worldwide public health problem. The spread of CL is highly associated with the socio-ecological interactions of vectors, hosts and the environment. The heterogeneity of these interactions has hindered CL modeling for healthcare preventive measures in endemic areas. In this study, an agent-based model (ABM) is developed to simulate the dynamics of CL spread based on a Geographic Automata System (GAS). A Susceptible-Exposed-Infected-Recovered (SEIR) approach together with Bayesian modeling has been applied in the ABM to explore the spread of CL. The model is then adapted locally for Isfahan Province, an endemic area in central Iran. The results from the model indicate that desertification areas are the main origin of CL, and riverside population centers have the potential to host more sand fly exposures and should receive more preventive measures from healthcare authorities. The results also show that healthcare service accessibility prevented exposures from becoming infected and areas with new inhabitants experienced more infections from same amount of sand fly exposures.