Water-soluble Tracer Research Articles

Diagnostics of gas-dynamic connection between gas caps and their influence on the product composition of the North Caspian production wells as per tracer tests

Diagnostics of gas-dynamic connection between gas caps and their influence on the product composition of the North Caspian production wells as per tracer tests

Of rats and rocks: using pre-clinical PET imaging facilities in core analysis

Positron emission tomography (PET) is routinely used for medical imaging; a current surge in published geoscientific research utilizing this modality also infer increasing interest for in-situ PET imaging in core analysis. Excellent signal to noise ratio coupled with high temporal and spatial resolution suggest that PET might become the new method-of-choice for core analysis. Obstacles related to production, transfer and handling of radioactive fluids and gases must, however, be dealt with for PET to become a widely used core scale imaging technique. This paper describes an ongoing, true multidisciplinary collaboration, where pre-clinical PET imaging facilities are routinely used in core analysis to investigate dynamic fluid flow at high pressure conditions. We detail challenges and opportunities related to porous media research in established pre-clinical laboratory facilities designed for small-animal imaging, and demonstrate the significant potential of PET imaging in core scale analysis in a context related to long-term porous media carbon storage. Explicit imaging of several fluid phases is possible by PET imaging using a range of readily available radiotracers. Relevant radiotracers to carbon storage in porous media are e.g. the carbon radioisotope 11C and water-soluble tracer 18F. These are both short-lived tracers (20 - 110 min) and must be used in high doses of radiation, which present challenges related to safe transfer and handling. Although there are several obstacles to conduct advanced core analysis in hospital imaging facilities (some of which are detailed in this paper), significant advantages include trained personnel on-site to operate a local cyclotron, procedures in place to ensure safe and efficient transfer of short-lived radiopharmaceuticals from the cyclotron, and advanced image analysis capabilities available. Cyclotrons are widely available worldwide (currently more than 1200 operating cyclotrons), often located in close proximity to medical and pre-clinical imaging facilities and academic institutions. Similar collaborations may therefore also be possible elsewhere, reducing the need for allocated geophysical PET-scanners and lowering the threshold for routinely using PET imaging in core analysis.

Precise measurement of intradermal fluid delivery using a low activity technetium-99m pertechnetate tracer

A method was developed and validated to determine the intradermal (ID) fluid delivery potential of several ID devices, including hollow microneedles. The novel method used water soluble technetium-99 m pertechnetate (99mTcO4−) diluted in normal saline to measure the volume of fluid delivered to and remaining in the skin. The fluid that back-flowed to the skin surface and the fluid left on the device surface were also quantified, thus capturing all fluid volumes deposited during intradermal injections. The technique described in this manuscript was used to assess the injection performance of conventional hypodermic needles and hollow microneedles ex vivo using porcine skin and in vivo with a rat model. Since only a small fraction, 1.1%, of the water-soluble tracer remained bound to the skin when applied topically, the technique can be used to differentiate between injected fluid and backflow. Counting of gamma radiation from 99mTcO4− provided sub-nanoliter resolution for volume measurements, making the proposed method powerful, sensitive, and suitable for the assessments of ID injection devices, particularly for vaccine delivery.

Chemical application strategies to protect water quality

Management of turfgrass on golf courses and athletic fields often involves application of plant protection products to maintain or enhance turfgrass health and performance. However, the transport of fertilizer and pesticides with runoff to adjacent surface waters can enhance algal blooms, promote eutrophication and may have negative impacts on sensitive aquatic organisms and ecosystems. Thus, we evaluated the effectiveness of chemical application setbacks to reduce the off-site transport of chemicals with storm runoff. Experiments with water soluble tracer compounds confirmed an increase in application setback distance resulted in a significant increase in the volume of runoff measured before first off-site chemical detection, as well as a significant reduction in the total percentage of applied chemical transported with the storm runoff. For example, implementation of a 6.1 m application setback reduced the total percentage of an applied water soluble tracer by 43%, from 18.5% of applied to 10.5% of applied. Evaluation of chemographs revealed the efficacy of application setbacks could be observed with storms resulting in lesser (e.g. 100 L) and greater (e.g. > 300 L) quantities of runoff. Application setbacks offer turfgrass managers a mitigation approach that requires no additional resources or time inputs and may serve as an alternative practice when buffers are less appropriate for land management objectives or site conditions. Characterizing potential contamination of surface waters and developing strategies to safeguard water quality will help protect the environment and improve water resource security. This information is useful to grounds superintendents for designing chemical application strategies to maximize environmental stewardship. The data will also be useful to scientists and regulators working with chemical transport and risk models.

Horizontal-Well Fracturing by Use of Coiled Tubing in the Belridge Diatomite: A Case History

Summary Coiled-tubing (CT) fracturing has been applied successfully in multistage vertical-well stimulation in the Belridge diatomite in the Lost Hills field. This same methodology was used to complete two northwest-trending horizontal wells drilled on the northeast flank of the Lost Hills anticlinal structure that targeted thinner, higher-oil-saturation strata separated by thicker lower-oil-saturation intervals. The target reservoir presents high-porosity, low-matrix-permeability, and low-Young's-modulus Opal A diatomite. The perforations were jetted by pumping sand slurry down the CT, and the fracture job was pumped down the annulus. The stages were isolated by setting sand plugs. Nine and twelve stages were pumped in the two wells, respectively. The perforation locations for different stages were selected in areas with high resistivity and inferred high oil saturations, an absence of hydraulic fractures from nearby wells, excellent cement bonding, and low intensity of natural fractures. These assessments followed logging-while-drilling (LWD) with gamma ray, induction-resistivity and azimuthally focused resistivity (AFR) (image) logs, and a cased-hole ultrasonic image tool (USIT) run with the aid of a tractor. The hydraulic fractures were monitored by use of surface tiltmeter sensors. Oil- and water-soluble tracers were pumped to determine the relative production contribution from the stages and fracture-fluid cleanup, respectively, from the stages. All the jobs could be pumped successfully without any screenouts. Challenges were faced in setting sand plugs and isolating stages. Large fracture widths and low leakoff into the formation led to difficulty in forming sand bridges at the perforations and concentrating sand in the wellbore for the plugs. Surface tiltmeters showed excessive fracture-height growth. Tracer results showed that 20 to 30% of the stages contributed to 50 to 60% of the production. Stages with higher treating pressures contributed less toward production. This could be attributed to near-wellbore tortuosity in these stages. Proppant flowback was encountered in one well, and after an effective cleanup, the production rose. The study illustrates how integration of various aspects, such as completion design, fracture-pressure analysis, and diagnostics, combined with geologic and reservoir information can help in identifying challenges and finding potential solutions for hydraulic fracturing. The findings highlight that the technology most suitable for vertical-well stimulation might not be favorable for horizontal-well stimulation.

A new device for characterizing fracture networks and measuring groundwater and contaminant fluxes in fractured rock aquifers

AbstractThis paper presents the fundamental theory and laboratory test results on a new device that is deployed in boreholes in fractured rock aquifers to characterize vertical distributions of water and contaminant fluxes, aquifer hydraulic properties, and fracture network properties (e.g., active fracture density and orientation). The device, a fractured rock passive flux meter (FRPFM), consists of an inflatable core assembled with upper and lower packers that isolate the zone of interest from vertical gradients within the borehole. The outer layer of the core consists of an elastic fabric mesh equilibrated with a visible dye which is used to provide visual indications of active fractures and measures of fracture location, orientation, groundwater flux, and the direction of that flux. Beneath the outer layer is a permeable sorbent that is preloaded with known amounts of water soluble tracers which are eluted at rates proportional to groundwater flow. This sorbent also captures target contaminants present in intercepted groundwater. The mass of contaminant sorbed is used to quantify cumulative contaminant flux; whereas, the mass fractions of resident tracers lost are used to provide measures of water flux. In this paper, the FRPFM is bench tested over a range of fracture velocities (2–20 m/day) using a single fracture flow apparatus (fracture aperture = 0.5 mm). Test results show a discoloration in visible dye corresponding to the location of the active fracture. The geometry of the discoloration can be used to discern fracture orientation as well as direction and magnitude of flow in the fracture. Average contaminant fluxes were measured within 16% and water fluxes within 25% of known imposed fluxes.

Water-soluble trace, rare earth elements and organic compounds in Arctic aerosol

We investigated the elemental composition and water-soluble-organic compounds (WSOC) present in size-segregated airborne particulate matter to better understand: (1) the distribution of the water-soluble fraction of trace elements (TE), rare earth elements (REE) and WSOCs among different particulate sizes, and (2) the transport processes of aerosol towards the Arctic zone. Samples were collected at Ny-Alesund in the Svalbard Islands (78°55′07″N, 11°53′30″E) from 19 April to 14 September 2010. Water-soluble TE and REE were measured with the aim of recognising reliable tracers of specific sources, which may prove crucial in cost-effective strategies of air pollution control. The TE and REE content, especially in the finest fractions of aerosols in remote areas, is primarily due to long-range transport. It gives valuable information on the global circulation and on the contribution of human activities to aerosol composition (Birmili et al. in Environ Sci Technol 40:1144–1153, 2006; Fernandez-Espinosa et al. in Atmos Environ 38:873–886, 2004; Song et al. in Atmos Environ 35:5277–5286, 2001). On the same samples, we also determined water-soluble organic tracers as specific source indicators: levoglucosan and methoxyphenols from biomass burning, acrylamide from anthropogenic origin and amino acids from primary production. These results were discussed in previous papers (Scalabrin et al. in Atmos Chem Phys 12:10453–10463, 2012; Zangrando et al. in Environ Sci Technol 47:8565–8574, 2013).

Mechanisms That Determine the Internal Environment of the Developing Brain: A Transcriptomic, Functional and Ultrastructural Approach

We provide comprehensive identification of embryonic (E15) and adult rat lateral ventricular choroid plexus transcriptome, with focus on junction-associated proteins, ionic influx transporters and channels. Additionally, these data are related to new structural and previously published permeability studies. Results reveal that most genes associated with intercellular junctions are expressed at similar levels at both ages. In total, 32 molecules known to be associated with brain barrier interfaces were identified. Nine claudins showed unaltered expression, while two claudins (6 and 8) were expressed at higher levels in the embryo. Expression levels for most cytoplasmic/regulatory adaptors (10 of 12) were similar at the two ages. A few junctional genes displayed lower expression in embryos, including 5 claudins, occludin and one junctional adhesion molecule. Three gap junction genes were enriched in the embryo. The functional effectiveness of these junctions was assessed using blood-delivered water-soluble tracers at both the light and electron microscopic level: embryo and adult junctions halted movement of both 286Da and 3kDa molecules into the cerebrospinal fluid (CSF). The molecular identities of many ion channel and transporter genes previously reported as important for CSF formation and secretion in the adult were demonstrated in the embryonic choroid plexus (and validated with immunohistochemistry of protein products), but with some major age-related differences in expression. In addition, a large number of previously unidentified ion channel and transporter genes were identified for the first time in plexus epithelium. These results, in addition to data obtained from electron microscopical and physiological permeability experiments in immature brains, indicate that exchange between blood and CSF is mainly transcellular, as well-formed tight junctions restrict movement of small water-soluble molecules from early in development. These data strongly indicate the brain develops within a well-protected internal environment and the exchange between the blood, brain and CSF is transcellular and not through incomplete barriers.

In-Plane Liquid Water Distribution at the Interface between the Gas Diffusion Layer and Catalyst Layer in the Cathode of a Polymer Electrolyte Fuel Cell with a Hybrid Pattern Flow Field

We have investigated the effect of flow field patterns without cathode humidification in a polymer electrolyte fuel cell (PEFC) using electrochemical impedance spectroscopy (EIS) with triple-parallel-serpentine, interdigitated, and serpentine-interdigitated hybrid flow fields. The hybrid flow fields exhibit better performance than the others. The EIS results indicate that dehydration of the membrane and catalyst layer (CL) is significant for the triple-parallel-serpentine flow fields whereas that for the hybrid flow fields is not so severe. Thus the serpentine-interdigitated hybrid flow field has advantage in cell operation without cathode humidification, possibly because it provides a relatively uniform current distribution due to the interdigitated flow channel, and in addition, the serpentine flow channel involved in the hybrid flow field supplies water vapor along the channel. This water distribution behavior is also indicated by ex-situ tracer distribution observation using gas diffusion layers sprayed with water soluble metal salt tracer at the CL side.

산성화 과정이 황사입자 내 금속성분의 용해도에 미치는 영향: 실험실 연구결과

Because some particulate matter emission sources may inherently produce soluble species, or some soluble species may be produced during atmospheric transport, it is important to understand the origin of a particles`s solubility when water-soluble tracers are used in source apportionment studies. Laboratory experiments were performed on three types of soils (Mongolia grassland, Mongolia desert, and Korean rural soils), to study the impact of acidification by nitric acid vapor on the solubility of metals in the soils. To achieve this goal, concentrations of water-soluble metals (Na, Mg, Al, K, Ca, Mn, and Fe) in the soils measured before and after acidification. Contributions of concentrations of water-soluble metal species before and after acidification attack to their total concentrations varied little with soil type. Concentrations of water-soluble Mg, Al, K, Ca, Mn, and Fe from the soils after interaction with nitric acid vapor increased, with significant increases in soluble Ca and Mn for all soil types suggesting soil acidification enhances the amount of leachable metal species in soil dust. There was little increase in water-soluble Na and K after acidification for each soil type. This experiment demonstrates that quantities of water-soluble metal species in particulate matter are produced under high gaseous nitric acid conditions.

Air-assisted sprayer adapted for precision horticulture: Spray patterns and deposition assessments in small-sized citrus canopies

An axial-fan air-assisted sprayer, adapted with variable rate nozzles and adjustable air-assist flow control, for citrus tree-specific precision spraying, was tested. Static experiments were conducted to determine spray patterns at varied nozzle flow rates and air-assistance settings. Spray patterns confirmed that the sprayer delivered variable liquid flow rates and the air-diverting louvre controlled the air-assistance providing targeted spray delivery. Field experiments were conducted to determine suitable air-assistance and nozzle combinations needed in the future for sensor-controlled spraying in young (small-sized) citrus canopies. Experiments involved two nozzle treatments, a) nozzles 1–6, and b) nozzles 2–3 at 100% output rates and three (40%, 70%, and 100%) levels of air assistance selected based on spray patterns. The sprayer was operated at a travel speed of 4.5 km h−1 and the water-soluble tracer deposition on biological and artificial targets, at 0.6 m and 1.4 m above ground and laterally at the canopy front, middle, and back, respectively were measured using fluorimetry. Results suggested that within nozzles 1–6 treatments with varied air-assist, 70% air-assistance was more effective for small sized canopies than 100% air-assistance; it appeared that the latter propelled the spray beyond the canopy and reduced the spray deposition efficiency. Also, for the citrus canopies studied, the use of two or three nozzles instead of the lower six nozzles (i.e. the control treatment) might be more suitable since they would result in 50% or less chemical usage while having comparable spray deposition to that of the control.

Tracer test for the measurement of gas diffusion and non-aqueous phase liquid (NAPL) saturation in soil

During soil bioremediation, the diffusion of oxygen into the soil is an important prerequisite for aerobic biodegradation, and the decrease of petroleum products is the ultimate goal. Both processes need to be monitored. The aim of this work was to develop a gas tracer test that yields information on both, gas diffusion and residual saturation with non-aqueous phase liquids (NAPLs) in unsaturated soil heaps. One conservative tracer (methane) and 4 partitioning gas tracers (diethylether, methyl tert-butyl ether, chloroform and n-heptane) were injected as vapors into laboratory columns filled with unsaturated sand with increasing NAPL saturation. Breakthrough curves of gaseous compounds were measured at two points and compared to analytical solutions of an analytical diffusive-reactive transport equation. By fitting of methane data, robust results for effective diffusivity (tortuosity) were obtained. NAPL saturation was most accurately measured by the moderately water soluble tracers (ethers and chloroform). The hydrophobic tracer n-heptane did not partition into water-immersed NAPL. An easy and accurate way to assess air–NAPL partitioning constants from gas chromatography retention times is furthermore reported. It is concluded that gas tracer tests have the potential for measuring two important properties in soil bioremediation systems easily and quickly.

Comparison of Positron Emission Tomography and X-ray radiography for studies of physical processes in sandstone

The migration of moisture in cores of porous homogeneous sandstone of Ledian age (Belgian Eocene, Tertiary) is monitored with PET ( Positron Emission Tomography) and micro-focus X-ray radiography. In the case of PET, a nuclear medical imaging technique, 55Co-EDTA ( Ethylene diamine Tetra acetic acid) and R- 18F were used as water-soluble tracers. The X-ray projection method has evolved from the better-known medical technique and allows a fast and accurate determination of the two-dimensional transient moisture content profiles. Results indicate that both techniques can deliver important information concerning physical processes in situ.

Development of water leak detection method in fusion reactors using water-soluble gas

A water leak detection method using krypton (Kr) as a water-soluble tracer has been proposed for fusion reactors with fully circulating the in-vessel cooling water. This method was targeted for applying to the International Thermonuclear Experimental Reactor (ITER), and the 10 −3 Pa m 3/s order of water leak valves were fabricated and connected to the water loop circuit. The water leaks were effused into the vacuum vessel evacuated by a cryopump and the water dissolved Kr was detected by a quadrupole mass spectrometer (QMS). When two leak valves with 1 m distance were attached to the test pipe with 30 °C heating, two distinct, the mass to charge number ratio ( m/ e) of 84 peak current rises caused by the water leak were successfully detected with the time interval of 39 s. On the other hand, the water accession length as a function of the traveling time was calculated by considering a natural convection flow caused by the 30 °C heating, where the traveling time was 44.6 s for the 1 m length. This means that the observed positional accuracy is 12.6%, based on the calculation. To enhance the positional accuracy, the detailed flow simulation is indispensable. This method can be applied to the ITER condition.

Water‐Soluble Dendrimeric Two‐Photon Tracers for In Vivo Imaging

In einer (Nuss)schale: Kovalent eingewickelt in eine schützende und Löslichkeit vermittelnde Dendrimerschale (siehe Bild) wird ein ursprünglich hydrophobes Zweiphotonenfluorophor zu einem stark emittierenden, biokompatiblen Kontrastmittel für die In-vivo-Bildgebung durch Multiphotonenmikroskopie.

Basis for the permeability barrier abnormality in lamellar ichthyosis.

The basis for the permeability barrier abnormality in lamellar ichthyosis (LI) is not known. LI is caused by mutations in the gene that encodes the enzyme, transglutaminase 1 (TGI), which is responsible for assembly of the cornified envelope (CE). TG1 also has been suggested recently to catalyze the covalent attachment of omega-hydroxyceramides (omega-OHCer) to the CE, forming the corneocyte-lipid envelope (CLE). We first assessed the barrier function and the permeability pathway of the water-soluble tracer, colloidal lanthanum, across the stratum corneum (SC) in patients with LI with absent (n = 4) or low (n = 2) TG1 activity/protein. Increased movement of tracer through the SC correlated with increased transcutaneous water loss, and tracer remained restricted to the SC interstices. Enhanced extracellular permeability, in turn, was explicable by truncation and fragmentation of extracellular lamellar membrane arrays. The resultant clefts in the SC interstices represent the likely pathway for increased water permeability. Moreover, tracer movement remained restricted to the interstices, despite the demonstration of increased corneocyte fragility associated with widespread variations in CE structure. Regardless of variability in CE structure, however, CLE structure and bound omega-OHCer content were normal. The normal CLE in LI may explain both the restriction of tracer to the SC interstices, as well as the presence of foreshortened membrane arrays with near-normal interlamellar dimensions. Finally, the demonstration of a normal CLE in LI also raises questions about the putative role of TG1 in forming the CLE. These results demonstrate: (1) the extracellular nature of increased permeability in LI; (2) discontinuities in extracellular membrane structures that account for the enhanced permeability in LI; (3) that these membrane abnormalities are both associated with and explained by abnormalities in the subjacent CE scaffold; and (4) an intact CLE is present in LI, despite abnormalities in the CE, which may restrict water movement to the SC interstices in LI.

Neuroadrenergic Denervation of the Lung in Type I Diabetes Mellitus Complicated by Autonomic Neuropathy

To verify whether autonomic neuropathy (AN) complicating type I, insulin-dependent diabetes mellitus affected neuroadrenergic bronchopulmonary innervation. Twenty nonsmoking diabetic patients without respiratory diseases were studied: 11 patients with AN (group AN) and 9 patients without AN (control; group C) diagnosed by standardized criteria. Patients underwent respiratory function tests and ventilatory scintigraphies with (123)I-metaiodobenzylguanidine (MIBG) and with (99m)Tc-diethylenetriaminepenta-acetic acid (DTPA) to assess both bronchopulmonary neuroadrenergic innervation and also permeability of the alveolar-capillary barrier to water-soluble tracers. Rates of pulmonary clearance of the two tracers were computed, and correlates were identified by nonparametric statistics. University hospital. The AN and C groups had normal respiratory function test results and comparable duration of diabetes and quality of metabolic control. (99m)Tc-DTPA clearance did not distinguish the groups. (123)I-MIBG clearance was faster in the AN group than in the C group (mean +/- SD half-time of the radiotracer time-activity curve [T(1/2)], 116.1 +/- 22.8 min in the AN group vs 139.5 +/- 18.3 min in the C group, p = 0.022), which is consistent with neuroadrenergic denervation in the AN group. (123)I-MIBG clearance was independent from (99m)Tc-DTPA clearance. Faster (123)I-MIBG clearance was significantly associated with worse performance in three of the four autonomic tests. Neuroadrenergic bronchopulmonary denervation may occur in diabetic patients with AN despite normal clinical and respiratory function findings. Further research is needed to identify clinical and prognostic implications of these findings.

Morphology of three lyotropic liquid crystalline biological NMR media studied by translational diffusion anisotropy.

The morphologies of three dilute liquid crystalline phases, which are widely used for biological NMR spectroscopy, are investigated by the study of tracer self-diffusion. The aqueous liquid crystalline media investigated include the common phospholipid bicelle medium, a phase consisting of a mixture of pentaethyleneglycol mono dodecyl ether and hexanol, and a medium containing cetylpyridinium bromide and hexanol. Threonine and water were used as tracer molecules for probing the aqueous environment, and tetramethylsilane (TMS) was for probing the lipophilic environment. Pulsed field gradient NMR was used to measure tracer self-diffusion rates in three orthogonal directions. Although results for the water-soluble tracers in bicelle media do not contradict the widely accepted disk-shaped bicelle model, the high TMS diffusion rate observed in the bilayer plane requires extensive transient edge-to-edge contacts of such disks. This morphology is essentially that of a heavily perforated lamellar bilayer phase and explains why this medium remains liquid crystalline well below the Onsager limit for disk-shaped nematogens. Below 25 degrees C, a bicelle mixture consisting of dimyristoyl phosphatidyl choline and dihexanoyl phosphatidyl choline remains isotropic, but tracer diffusion obstruction indicates that the particles are significantly oblate. The diffusion anisotropy in the penta(ethyleneglycol) mono dodecyl ether liquid crystals confirms the previously proposed alpha-lamellar phase. However, weak inhibition of aqueous-phase self-diffusion in the z direction points to the presence of bridge- or caplike obstructions, and the bilayers appear slightly permeable to water. If the previously proposed concentric cylinder superstructure of bilayers applies, the diffusion data indicate that the most outer cylinder must have a diameter greater than 50 microm. The tracer self-diffusion data for the cetylpyridinium bromide/hexanol medium is only compatible with a planar alpha-lamellar phase, with its local director orthogonal to the magnetic field, and a very large domain size over which the director remains parallel.

Pathogenesis of the Permeability Barrier Abnormality in Epidermolytic Hyperkeratosis

Epidermolytic hyperkeratosis is a dominantly inherited ichthyosis, frequently associated with mutations in keratin 1 or 10 that result in disruption of the keratin filament cytoskeleton leading to keratinocyte fragility. In addition to blistering and a severe disorder of cornification, patients typically display an abnormality in permeability barrier function. The nature and pathogenesis of the barrier abnormality in epidermolytic hyperkeratosis are unknown, however. We assessed here, first, baseline transepidermal water loss and barrier recovery kinetics in patients with epidermolytic hyperkeratosis. Whereas baseline transepidermal water loss rates were elevated by approximately 3-fold, recovery rates were faster in epidermolytic hyperkeratosis than in age-matched controls. Electron microscopy showed no defect in either the cornified envelope or the adjacent cornified-bound lipid envelope, i.e., a corneocyte scaffold abnormality does not explain the barrier abnormality. Using the water-soluble tracer, colloidal lanthanum, there was no evidence of tracer accumulation in corneocytes, despite the fragility of nucleated keratinocytes. Instead, tracer, which was excluded in normal skin, moved through the extracellular stratum corneum domains. Increasing intercellular permeability correlated with decreased quantities and defective organization of extracellular lamellar bilayers. The decreased lamellar material, in turn, could be attributed to incompletely secreted lamellar bodies within granular cells, demonstrable not only by several morphologic findings, but also by decreased delivery of a lamellar body content marker, acid lipase, to the stratum corneum interstices. Yet, after acute barrier disruption a rapid release of preformed lamellar body contents was observed together with increased organelle contents in the extracellular spaces, accounting for the accelerated recovery kinetics in epidermolytic hyperkeratosis. Accelerated recovery, in turn, correlated with a restoration in calcium in outer stratum granulosum cells in epidermolytic hyperkeratosis after barrier disruption. Thus, the baseline permeability barrier abnormality in epidermolytic hyperkeratosis can be attributed to abnormal lamellar body secretion, rather than to corneocyte fragility or an abnormal cornified envelope/cornified-bound lipid envelope scaffold, a defect that can be overcome by external applications of stimuli for barrier repair.

Overcoming electrically induced artifacts in penetration studies with fluorescent tracers

The use of model molecules in transdermal transport studies reveals transport behavior while providing an economical setup by detection of readily measured quantities such as fluorescence, radioactivity or absorbance of low-cost substances. Water soluble fluorescent tracers such as calcein have been repeatedly used as model molecules in transdermal transport studies. However, if electrically enhanced calcein transport across the human skin barrier is measured, artifacts due to interaction between calcein and electrode byproducts influence the result. Here, we describe an experimental setup which avoids known artifacts and makes calcein or other fluorescent tracers a suitable model for transdermal transport studies.