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Methods of Assessing Skin Irritation and Sensitization of Jet Fuels
Published in Mark L. Witten, Errol Zeiger, Glenn D. Ritchie, Jet Fuel Toxicology, 2010
R. Jayachandra Babu, Ram Patlolla, Mandip Singh
The microdialysis (MD) technique involves the insertion of a semipermeable membrane underneath the epidermis or in the dermis using a guiding cannula and continuous sampling of biomarkers from the extracellular fluids by pumping a physiological fluid through the semipermeable membrane at a constant rate. The extracellular substances diffuse through the membrane against a concentration gradient. This is a well-established technique for the continuous sampling of biomarkers of disease within the extracellular fluid space in vivo. It has several advantages over other sampling techniques in that it can be used to follow temporal variations in the generation and release of a biomarker at a discrete location within the tissue space. Furthermore, this technique can be directly adapted to humans to measure molecular responses in the skin, without having to collect biopsy samples. There are some excellent review articles in the literature describing skin MD technique (e.g., Kreilgaard, 2002; Clough, 2005; Ao and Stenken, 2006). Microdialysis of large molecular compounds is often difficult because of poor recovery of the macromolecules in the dialysate samples. Several different factors such as dilution effect inherent to microdialysis, low concentrations of inflammatory mediators, and relatively low sensitivity of ELISA techniques have been attributed to the limited use of the microdialysis technique in inflamed skin. By using a larger surface area of membranes (longer probes), large-molecular-weight cutoff probes, and the addition of bovine serum albumin (or dextran and surfactants), higher biomarkers recoveries can be achieved. Few studies have used MD to assess the release of neuropeptides and inflammatory cytokines in dermal neurogenic inflammation (Schmelz et al., 1997). We studied the effect of jet fuel (JP-8) and xylene (a representative aromatic component of JP-8) on skin irritation in rats by measuring the expression of inflammatory biomarkers, Substance P (SP) and prostaglandin E2 (PGE2), in the skin using the MD technique (Fulzele et al., 2007). Occlusive exposure (2 hours) of hairless rats to JP-8 induced significantly higher release of SP and PGE2 as compared to control values. The JP-8 skin irritation effect was prevented by pretreatment with SR-140333 and celecoxib (Fulzele et al., 2007). The MD technique was also used to assess the skin irritation effect of JP-8 aliphatic hydrocarbons such as nonane, dodecane, and tetradecane by measuring SP, PGE2 α-MSH, and IL-6 in hairless rats (Patlolla et al., 2009). As shown in Table 8.1, nonane increased all the biomarker levels in significant amounts within 2 hours of chemical exposure compared to dodecane and tetradecane. In this study we demonstrated the potential of the MD technique to quantify the biomarkers in the skin as function of time.
Design of non-invasive glucose meter using near-infrared technique
Published in Journal of Medical Engineering & Technology, 2018
Gameel Saleh, Fatimah Alkaabi, Noor Al-Hajhouj, Fatimah Al-Towailib, Safa Al-Hamza
This method depends on the sampling of the interstitial fluid found in the skin or in the subcutis to measure blood glucose level by using subcutaneous electrochemical sensor or biosensor implanted in the abdominal region or by using microdialysis technology [4,8].
Fatigue: Is it all neurochemistry?
Published in European Journal of Sport Science, 2018
More recently, Hasegawa et al. (2008), Hasegawa, Ishiwata, et al. (2005) and Hasegawa, Meeusen, et al. (2005) performed a series of experiments on the effects of tetrodotoxin (TTX) and bupropion (a DA/NA reuptake inhibitor) on exercise behaviour and/or thermoregulation in freely moving or exercising rats. TTX, a poison of the Japanese puffer fish that acts as a sodium channel blocker, is widely used for blockage of neurotransmission in specific brain regions. When employed together with brain microdialysis, this method can be used to elucidate possible mechanisms of neurotransmitter action (Hasegawa, Ishiwata, et al., 2005). Hasegawa, Ishiwata, et al. (2005) concluded that perfusion of TTX into the PO/AH induced a significant increase in body temperature with a significant decrease in tail temperature and an elevation in heart rate. Interestingly, the TTX-induced hyperthermia was found without a change in exercise behaviour. Hasegawa, Meeusen, et al. (2005) and Hasegawa et al. (2008) looked at the effects of bupropion on thermoregulation and brain neurotransmitter levels in freely moving rats and on performance in exercising rats. In freely moving rats, the injection of the dual DA and NA reuptake inhibitor induced a significant increase in brain and core temperature with a decrease in heat loss responses (decreased tail temperature). These thermal responses were accompanied by an increase of the extracellular concentrations of NA and DA with no effect on serotonin release in the PO/AH (Hasegawa, Meeusen, et al., 2005). In a follow-up experiment the rats were forced to exercise at a speed of 26 m min−1 on a treadmill until exhaustion at 18°C (no drug), 30°C with saline or 30°C with bupropion (Hasegawa et al., 2008). Running time to exhaustion was significantly shorter at 30°C than at 18°C. At 30°C, running time to exhaustion was significantly increased by bupropion compared with the saline condition. Furthermore, significantly higher brain and core temperatures were observed in the bupropion trial. These changes in brain and core temperature were accompanied by an increase in the extracellular concentrations of DA and NA in the PO/AH.