Fresh Porcine Skin Research Articles

Tape Stripping Method in Dermatological and Pharmacological Research: Evaluating Fresh and Frozen-Thawed Porcine Skin.

Background The stratum corneum (SC) plays a crucial role in protecting the skin and regulating water loss. Tape stripping is a well-established method for studying skin barrier function and evaluating topical treatments. However, the behavior of fresh versus frozen-thawed skin during tape stripping has not been extensively compared. Objective This study aims to compare the removal of the stratum corneum from fresh and frozen-thawed porcine skin using tape stripping. It also aims to assess the reliability of tape weighing versus histological methods in quantifying SC removal. Methods Fresh and frozen-thawed porcine ears were obtained, cleaned, and subjected to tape stripping at varying numbers of strips from zero to 40. Tape weight and histological measurements were used to quantify SC removal. Statistical analyses were conducted to compare SC thickness and tape weight between the two types of skin. Results The study found that frozen-thawed skin exhibited a non-linear rate(r = 0.65) of SC removal per tape strip in the first five strips compared to a linear removal for fresh skin (r = 0.96). By the fifth tape strip, frozen-thawed samples had lost 80.6% of their SC, while fresh samples had only lost 33.5% (P < 0.03). Tape weighing and histological measurements showed strong correlations (r = 0.93 for fresh skin and r = 0.95 for frozen-thawed skin), indicating that tape weighing is a reliable alternative to histology for assessing SC removal on both sample types. Conclusions Fresh and frozen-thawed porcine skin respond differently to tape stripping, with frozen-thawed skin showing accelerated SC removal in the first five strips. The strong correlation between tape weighing and histological analysis supports the use of tape weighing as a practical tool for evaluating SC removal. These findings have implications for specimen selection and methodological standardization in dermatological and pharmacological research. Future research should explore alternative preservation and SC thickness measurement methods and their impact on tape stripping outcomes.

Characterising Skin Electrical Impedance Using Tape Stripping Methods: A Bioelectrical Study of a Porcine Model.

Background Recent advancements in ultra-low power electronics and wireless devices have facilitated the widespread adoption of wearable technology for fitness and health monitoring, paving the way for personalized medicine. Microneedle-based devices, comprising small epidermal patches that penetrate the skin's stratum corneum to potentially access biomarkers in the extracellular fluid of the viable epidermis, represent a promising innovation in this field. Objectives This project aimed to develop and validate a novel method to evaluate microneedle engagement in the skin in real-time. To our knowledge, there are no studies published to date that have characterized the electrical impedance of stratum corneum and epidermis using the tape stripping method to selectively remove cell layers. Additionally, no studies have been published comparing the electrical impedance of fresh to frozen-thawed porcine skin. The objective of this study was to develop and validate a novel method to evaluate microneedle engagement in skin, in real-time, that does not require processing of the tissue. Methods A tape stripping technique was employed to selectively remove the stratum corneum from fresh and frozen-thawed porcine skin samples which were then electrically characterized using an excitation frequency of 5 kHz with a peak Voltage of 1 V. Results This study demonstrated a mean impedance reduction of 97.08 ± 1.3 % for fresh porcine skin, and 98.04 ± 0.3 % for frozen-thawed porcine skin when transitioning from the surface stratum corneum to the viable epidermis. The correlation between the reduction of impedance and the number of tape strips across all 18 test sites was significant (r = 0.98, p < 0.00001). However, comparing the skin impedance of the fresh and frozen-thawed specimens showed poor equivalence, with the frozen-thawed sites approximately 5.5 times the impedance of the fresh sites before any tape stripping, and 4.19 times greater after 30 tape strips. Conclusions These findings suggest that monitoring for an interelectrode impedance decrease of greater than 95% between two projections of a microneedle device could provide a rapid and effective evaluation of skin engagement, crucial for advancing the development and clinical application of microneedle-based technologies in personalized medicine. The study also underscores the impact of the freeze-thaw process on the mechanical and electrical properties of skin, which is crucial for standardizing testing protocols.

Multi-Modal Spectroscopic Assessment of Skin Hydration.

Human skin acts as a protective barrier, preserving bodily functions and regulating water loss. Disruption to the skin barrier can lead to skin conditions and diseases, emphasizing the need for skin hydration monitoring. The gold-standard sensing method for assessing skin hydration is the Corneometer, monitoring the skin's electrical properties. It relies on measuring capacitance and has the advantage of precisely detecting a wide range of hydration levels within the skin's superficial layer. However, measurement errors due to its front end requiring contact with the skin, combined with the bipolar configuration of the electrodes used and discrepancies due to variations in various interfering analytes, often result in significant inaccuracy and a need to perform measurements under controlled conditions. To overcome these issues, we explore the merits of a different approach to sensing electrical properties, namely, a tetrapolar bioimpedance sensing approach, with the merits of a novel optical sensing modality. Tetrapolar bioimpedance allows for the elimination of bipolar measurement errors, and optical spectroscopy allows for the identification of skin water absorption peaks at wavelengths of 970 nm and 1450 nm. Employing both electrical and optical sensing modalities through a multimodal approach enhances skin hydration measurement sensitivity and validity. This layered approach may be particularly beneficial for minimising errors, providing a more robust and comprehensive tool for skin hydration assessment. An ex vivo desorption experiment was carried out on fresh porcine skin, and an in vivo indicative case study was conducted utilising the developed optical and bioimpedance sensing devices. Expected outcomes were expressed from both techniques, with an increase in the output of the optical sensor voltage and a decrease in bioimpedance as skin hydration decreased. MLR models were employed, and the results presented strong correlations (R-squared = 0.996 and p-value = 6.45 × 10-21), with an enhanced outcome for hydration parameters when both modalities were combined as opposed to independently, highlighting the advantage of the multimodal sensing approach for skin hydration assessment.

Porcine skin ablation using mid-infrared picosecond pulse burst

We present the porcine skin ablation using a mid-infrared high-repetition-rate picosecond pulse burst laser. A burst-mode pulse with a repetition rate of 16.32 MHz was generated from a home-built difference frequency generation (DFG) system operating at 3 μm. Within each burst, there were 16 equally spaced 8.5 ps sub-pulses at an intra-burst repetition rate of ∼3.3 GHz. To study the laser-tissue interaction, laser powers of 1 to 2 W, and scanning times from 1 to 10 with spot size of ∼50 μm were applied to irradiate the fresh porcine skin. The results demonstrate that the burst-mode pulse with modest peak power density of MW/cm2 is efficient for tissue ablation. The optimized ablation depth increased with the average power and scanning times, reaching a maximal incision depth of 150 μm. Thanks to the high repetition rate of intra-burst pulse and high absorption of radiation, the ablation width and thermal effect width kept within 50 μm and 25 μm in all control groups. It is believed that as the first demonstration, such mid-infrared burst-mode laser radiation with modest power intensity is of great potential to realize micron penetration depth and low thermal effect in high-precision surgery applications.

Natural extracts-meditated efficient and electrically responsive bioglues

Bioglues have great potential in the field of biomedical engineering concerning interfacial adhesion. Based on naturally extracted chitosan and benzoic acids, we developed low-viscosity bioglues capable of achieving an efficient and strong interfacial adhesion to wet skin tissues without any additional post-treatment. Owing to the synergy of topology, electrostatic interaction and self-hydrophobization, the adhesive strength could reach as high as 110 kPa when two pieces of fresh porcine skin were adhered together with the bioglues for one minute. Subsequently, we showed that the bioglue-regulated interfacial adhesion was essentially sensitive to external electrical fields with voltages less than 1 V, which might thus cause an electrically responsive adhesion. Likewise, we revealed that the phenol–quinone transition played a dominant role in inducing changes in interfacial adhesion strength modulated by the applied electric fields. By introducing a circuit model to mimic electric stimulation, we further recognized that an electric field of ∼2500 V/m was the threshold required for the electrically regulated phenol–quinone transition. Further, the bioglues were biocompatible, antibacterial and promoted wound healing, making them more suitable for applications in smart interfacial adhesion-related areas like biomedicine, flexible electronics and soft robotics.

The biophysical effects of localized electrochemical therapy on porcine skin

BackgroundMinimally-invasive methods to treat scars address a common pathway of altering collagen structure, leading to collagen remodeling. ObjectiveIn this study, we employed in situ redox chemistry to create focal pH gradients in skin, altering dermal collagen, in a process we refer to as electrochemical therapy (ECT). The effects of ECT to induce biochemical and structural changes in ex vivo porcine skin were examined. MethodsDuring ECT, two platinum electrodes were inserted into fresh porcine skin, and following saline injection, an electrical potential was applied. pH mapping, high frequency ultrasonography, and two photon excitation microscopy and second harmonic generation (SHG) microscopy were used to evaluate treatment effects. Findings were correlated with histology. ResultsFollowing ECT, pH mapping depicted acid and base production at anode and cathode sites respectively, with increasing voltage and application time. Gas formation during ECT was observed with ultrasonography. Anode sites showed significant loss of SHG signal, while cathode sites showed disorganized collagen structure with fewer fibrils emitting an attainable signal. Histologically, collagen denaturation at both sites was confirmed. ConclusionWe demonstrated the production of in situ acid and base in skin occurring via ECT. The effects chemically and precisely alter collagen structure through denaturation, giving insight on the potential of ECT as a simple, low-cost, and minimally-invasive means to remodel skin and treat scars.

Terahertz signal analysis for biological tissues based on empirical mode decomposition

We propose an empirical mode decomposition (EMD) based method for terahertz (THz) signal analysis to differentiate different biological tissues. The THz signals reflected from fresh porcine muscle and skin tissues were observed. The time-domain THz signals of the tissues are decomposed into a series of components called the intrinsic mode functions (IMFs). It is found that the decomposed low-order IMFs, especially the first-order IMF, have better performance to distinguish different tissues. Because the first-order IMF contains most of the energy from the original signal in the higher frequency range, in which tissue water has lager absorption of THz wave. The proposed strategy provides a supplementary and more efficient way for biological tissues characterization.

Acousto-mechanical behaviour of ex-vivo skin: Nonlinear and viscoelastic properties

The mechanical behaviour of skin is significant for some applications including dermatology, surgery, and impact biomechanics science. In this work, we have investigated the study of the acousto-mechanical viscoelastic properties of skin. For that, both tensile-relaxation and ultrasonic tests were conducted on porcine tissue samples in fibre directions. To understand the complex skin aging phenomena, we used strength tensile test correlated with the Nonlinear Time Reversal signal processing tool extension “TR-NEWS”. Uniaxial tensile tests were carried out at a strain rate of 5⋅10−3 mms−1 on skin using a load-relaxation-discharge load path with increasing amplitude and offset. This work is also under way to extend the frequency range of ultrasounds to 50 MHz. Digital Image Correlation was used for 2D strain measurement of the dermis. From this analysis, we conclude that fresh porcine skin should be modelled as a nonlinear viscoelastic material with strain-rate dependence. The obtained hysteresis loop shall be taken as significant skin damage.

Association of Electrochemical Therapy With Optical, Mechanical, and Acoustic Impedance Properties of Porcine Skin.

The classic management of burn scars and other injuries to the skin has largely relied on soft-tissue transfer to resurface damaged tissue with local tissue transfer or skin graft placement. In situ generation of electrochemical reactions using needle electrodes and an application of current may be a new approach to treat scars and skin. To examine the changes in optical, mechanical, and acoustic impedance properties in porcine skin after electrochemical therapy. This preclinical pilot study, performed from August 1, 2015, to November 1, 2016, investigated the effects of localized pH-driven electrochemical therapy of ex vivo porcine skin using 24 skin samples. Platinum-plated needle electrodes were inserted into fresh porcine skin samples. A DC power supply provided a voltage of 4 to 5 V with a 3-minute application time. Specimens were analyzed using optical coherence tomography, optical coherence elastography, and ultrasonography. Ultrasonography was performed under 3 conditions (n = 2 per condition), optical coherence tomography was performed under 2 conditions (n = 2 per condition), and optical coherence elastography was performed under 2 conditions (n = 2 per condition). The remaining samples were used for the positive and negative control groups (n = 10). Platinum-plated needle electrodes were inserted into fresh porcine skin samples. A DC power supply provided a voltage of 4 to 5 V with a 3-minute application. Tissue softening was observed at the anode and cathode sites as a result of electrochemical modification. Volumetric changes were noted using each optical and acoustic technique. A total of 24 ex vivo porcine skin samples were used for this pilot study. Optical coherence tomography measured spatial distribution of superficial tissue changes around each electrode site. At 4 V for 3 minutes, a total volumetric effect of 0.47 mm3 was found at the anode site and 0.51 mm3 at the cathode site. For 5 V for 3 minutes, a total volumetric effect of 0.85 mm3 was found at the anode site and 1.05 mm3 at the cathode site. Electrochemical therapy is a low-cost technique that is on par with the costs of suture and scalpel. The use of electrochemical therapy to create mechanical and physiologic changes in tissue has the potential to locally remodel the soft-tissue matrix, which ultimately may lead to an inexpensive scar treatment or skin rejuvenation therapy. NA.

Composite multiscale entropy analysis of reflective terahertz signals for biological tissues

We demonstrate a composite multiscale entropy (CMSE) method of terahertz (THz) signal complexity analysis to distinguish different biological tissues. The THz signals reflected from fresh porcine skin and muscle tissues were measured and analyzed. The statistically significant difference and separation of the two tissues based on several parameters were analyzed and compared for THz spectroscopy and imaging, which verified the better performance of the CMSE method and further enhancement of the contrast among THz signals that interact with different tissues. This process provides a better analysis and discrimination method for THz spectroscopy and imaging in biomedical applications.

Effect of Ultrasound-Enhanced Transdermal Drug Delivery Efficiency of Nanoparticles and Brucine.

Brucine is the active component in traditional Chinese medicine “Ma-Qian-Zi” (Strychnos nux-vomica Linn), with capabilities of analgesic, anti-inflammatory, anti-tumor and so on. It is crucial how to break through the impact of cuticle skin which reduces the penetration of drugs to improve drug transmission rate. The aim of this study is to improve the local drug concentration by using ultrasound. We used fresh porcine skin to study the effects of ultrasound on the transdermal absorption of brucine under the influence of various acoustic parameters, including frequency, amplitude and irradiation time. The transdermal conditions of yellow-green fluorescent nanoparticles and brucine in skin samples were observed by laser confocal microscopy and ultraviolet spectrophotometry. The results show that under ultrasonic conditions, the permeability of the skin to the fluorescent label and brucine (e.g., the depth and concentration of penetration) is increased compared to its passive diffusion permeability. The best ultrasound penetration can make the penetration depth of more than 110 microns, fluorescent nanoparticles and brucine concentration increased to 2-3 times. This work will provide supportive data on how the brucine is better used for transdermal drug delivery (TDD).

Ultrasound-mediated transdermal drug delivery of fluorescent nanoparticles and hyaluronic acid into porcine skin in vitro**Project partially supported by the National Natural Science Foundation of China (Grant Nos. 81127901, 81227004, 81473692, 81673995, 11374155, 11574156, 11274170, 11274176, 11474001, 11474161, 11474166, and 11674173), the Natural Science Foundation of Jiangsu Province, China (Grant No. BK2011812), the Fundamental Research Funds for the Central Universities, and

Transdermal drug delivery (TDD) can effectively bypass the first-pass effect. In this paper, ultrasound-facilitated TDD on fresh porcine skin was studied under various acoustic parameters, including frequency, amplitude, and exposure time. The delivery of yellow–green fluorescent nanoparticles and high molecular weight hyaluronic acid (HA) in the skin samples was observed by laser confocal microscopy and ultraviolet spectrometry, respectively. The results showed that, with the application of ultrasound exposures, the permeability of the skin to these markers (e.g., their penetration depth and concentration) could be raised above its passive diffusion permeability. Moreover, ultrasound-facilitated TDD was also tested with/without the presence of ultrasound contrast agents (UCAs). When the ultrasound was applied without UCAs, low ultrasound frequency will give a better drug delivery effect than high frequency, but the penetration depth was less likely to exceed 200 μm. However, with the help of the ultrasound-induced microbubble cavitation effect, both the penetration depth and concentration in the skin were significantly enhanced even more. The best ultrasound-facilitated TDD could be achieved with a drug penetration depth of over 600 μm, and the penetration concentrations of fluorescent nanoparticles and HA increased up to about 4–5 folds. In order to get better understanding of ultrasound-facilitated TDD, scanning electron microscopy was used to examine the surface morphology of skin samples, which showed that the skin structure changed greatly under the treatment of ultrasound and UCA. The present work suggests that, for TDD applications (e.g., nanoparticle drug carriers, transdermal patches and cosmetics), protocols and methods presented in this paper are potentially useful.

Development and Validation of an Artificial Mechanical Skin Model for the Study of Interactions between Skin and Microneedles

Microneedles are small needle‐like structures that are almost invisible to the naked eye. They have an immense potential to serve as a valuable tool in many medical applications, such as painless vaccination. Microneedles work by breaking through the stratum corneum, the outermost barrier layer of the skin, and providing a direct path for drug delivery into the skin. A lot of research has been presented over the past two decades on the applications of microneedles, yet the fundamental mechanism of how they interact, pressure, and penetrate the skin in its native state is worth examining further. As such, a major difficulty with understanding the mechanism of microneedle–skin interaction is the lack of an artificial mechanical human skin model to use as a standardized substrate. In this research news, the development of an artificial mechanical skin model based on a thorough mechanical study of fresh human and porcine skin samples is presented. The artificial mechanical skin model can be used to study the mechanical interactions between microneedles and skin, but not diffusion of molecules across skin. This model can assist in improving the performance of microneedles by enhancing the reproducibility of microneedle depth insertions for optimal drug delivery and biosensing. image

Investigation of dental materials as skin simulants for forensic skin/skull/brain model impact testing.

The purpose of this study was to measure the tear strength and hardness of four different dental silicones in comparison to that of porcine skin. Specimens were prepared (n = 20/group) according to ASTM D624-00, using three hydrophilic vinyl polysiloxane impression materials, one duplication silicone, and fresh porcine skin. A universal testing machine was used to strain each test specimen until complete rupture and calculate its tear strength (kNm(-1)). Failure analysis was then conducted using a stereoscopic zoom light microscope, as well as a scanning electron microscope (SEM). A shore A-type durometer was used to measure the hardness of all specimens. The tear strength for the silicones ranged from 1.75 to 9.58 kNm(-1) and the pigskin from 3.65 to 56.40 kNm(-1). The mean shore hardness for the silicones ranged from 16.275 to 62.65DU and the pigskin had a mean shore hardness of 22.65DU, with p values <0.0125 (0.05/4). Failure analysis of the silicone materials showed the origin of failure being in the tension side of the specimens and typical failure patterns were observed. Examining the materials under a SEM revealed that materials with higher viscosity presented with a larger amount of filler particle content than silicones with low viscosity, with the duplication silicone having no filler content. Dental silicones are a good alternative for skin in studies that require a skin simulant.

Texture Profile Analysis and Functional Properties of Gelatin from the Skin of Three Species of Fresh Water Fish

The texture profile analysis and functional properties of gelatin from fresh water fish (carps) and porcine skin were measured. Texture profile analysis revealed that the porcine gelatin showed significantly higher values for hardness, springiness, cohesiveness, gumminess, and chewiness than carp skin gelatin (p < 0.05). The bloom strength of gelatin from a porcine source was higher (466.40 g) than carp skin. The solubility profile of gelatin from carps and porcine as function of sodium chloride concentration indicated a maximum solubility at 0.3 M. The relationship between emulsion capacity values and concentration of proteins were found to be inversed in all of the gelatin samples.

Efficacies of treating large area third-degree burns by tangential excision and skin grafting for subcutaneous tissue wounds

To explore the efficacies of treating patients with large area third-degree burns by tangential excision and skin grafting for subcutaneous tissue wounds. From January 2002 to December 2013, the medical records were retrospectively reviewed for 31 consecutive adult patients with a third-degree burn area exceeding 70% and undergoing tangential excision and skin grafting on subcutaneous tissue wound (TESGSTW) for the first time within 7 days postburn at Burn Center, Affiliated Jinan Central Hospital, Shandong University. For 31 patients, wounds with relative integrity eschar underwent TESGSTW by stages. Tourniquet was not used in some extremities. The relevant clinical data including patient condition on admission, causes of death, blood loss of tangential excision wound, surgical procedures and efficacies in cured group were analyzed. Average age, burn total area and third-degree burn area of 31 patients were (32.4 ± 12.8) years, (89.0 ± 6.2)% and (80.4 ± 7.6)% respectively. There were inhalation injury (n = 25, 80.6%) and early-stage shock before hospitalization (n = 22, 71.0%). Among 18 cured ones (58.1%), 2 patients had a third-degree burn area ≥ 90%. And 13 patients (41.9%) died and 10 of them died at 4 to 19 days postburn. Burn area was a risk factor of burn mortality. Sepsis and multiple organ dysfunction syndrome (MODS) were major mortality causes. Four patients died from early-stage sepsis. Within 14 days postburn, average blood loss volume per 1% tangential excision area in non-tourniquet group was slightly higher than that in the tourniquet group, but the difference was insignificant. For 18 cured patients, TESGSTW were performed 41 times. For 14 patients (77.8%), TESGSTW was performed twice. The average time of the first tangential excision was (4.1 ± 0.6) days postburn, the time interval between the first two tangential excisions was (6.4 ± 2.0) days, the first tangential excision area (33.8 ± 7.6)% and accumulated tangential excision area (58.4 ± 10.8)%. Among 39 operations within 14 days postburn, refrigerated allogeneic or fresh porcine skin grafts were involved 33 times (84.6%). The wounds were fresh and bleeding after peeling 5 to 7 days postoperation. The time of allogeneic (xenogeneic) skin removal or rejection, recipient bed debridement and auto-skin grafting was (18.0 ± 4.8) days postoperation. And the auto-skin survival rate was (89.5 ± 9.5)%. Wound infection occurred 5 times in 4 patients. During a follow-up period of 6-108 months after TESGSTW, healed wound surface was plump and contraction relatively mild and non-prone to ulceration. And both extensibility and sensitivity were good. TESGSTW is safe for treating patients with large area third-degree burns. And its short and long-term outcomes are favorable.

Photostability of cosmetic UV filters on mammalian skin under UV exposure.

Previous studies showed that the common UV filter substances benzophenone-3 (BP-3), butyl methoxydibenzoylmethane (BM-DBM), octocrylene (OCR), ethylhexyl methoxycinnamate (EHMC), ethylhexyl salicylate (EHS) and ethylhexyl triazone (EHT) were able to react with amino side chains of different proteins in vitro. To transfer the results to mammalian skin conditions, sunscreen products were applied on both prepared fresh porcine skin and glass plates, followed by UV irradiation and the determination of depletion of the respective UV filters. Significantly lower recoveries of the UV filters extracted from skin samples than from glass plates indicated the additional reaction of the UV filters with skin constituents, when proteins will be the most important reactants. Among the products tested, BP-3 showed the greatest differences in recoveries between glass and skin samples of about 13% and 24% after 2 and 4 h of irradiation, respectively, followed by EHS > BM-DBM > OCR > EHMC > EHT. The obtained results raise the question, whether the common in vitro evaluations of sunscreens, using inert substrate materials like roughened quartz or polymethyl methacrylate (PMMA) plates are really suitable to fully replace in vivo methods, as they cannot include skin-typical reactions.

Optical tracking of local surface wave for skin viscoelasticity

Rapid and effective determination of biomechanical properties is important in examining and diagnosing skin thermal injury. Among the methods used, viscoelasticity quantification is one of the most effective methods in determining such properties. This study aims to rapidly determine skin viscoelasticity by optically tracking the local surface wave. New elastic and viscous coefficients were proposed to indicate skin viscoelasticity based on a single impulse response of the skin. Experiments were performed using fresh porcine skin samples. Surface wave was generated in a single impulse using a vibrator with a ball-tipped device and was detected using a laser Doppler vibrometer. The motions along the depth direction were monitored using an ultrasound system. The ultrasound monitoring results indicated the multi-layered viscoelasticity of the epidermis and dermis. The viscoelastic coefficients from four healthy samples show a potential viscoelasticity variation of porcine skin. In one sample, the two coefficients were evidently higher than those in a healthy area if the skin was slightly burned. These results indicate that the proposed method is sensitive, effective, and quick in determining skin viscoelasticity.

Hyperspectral fluorescence lifetime imaging for optical biopsy

A hyperspectral fluorescence lifetime imaging (FLIM) instrument is developed to study endogenous fluorophores in biological tissue as an optical biopsy tool. This instrument is able to spectrally, temporally, and spatially resolve fluorescence signal, thus providing multidimensional information to assist clinical tissue diagnosis. An acousto-optic tunable filter (AOTF) is used to realize rapid wavelength switch, and a photomultiplier tube and a high-speed digitizer are used to collect the time-resolved fluorescence decay at each wavelength in real time. The performance of this instrument has been characterized and validated on fluorescence tissue phantoms and fresh porcine skin specimens. This dual-arm AOTF design achieves high spectral throughput while allowing microsecond nonsequential, random wavelength switching, which is highly desirable for time-critical applications. In the results reported here, a motorized scanning stage is used to realize spatial scanning for two-dimensional images, while a rapid beam steering technique is feasible and being developed in an ongoing project.

Antibiotic susceptibility and resistance of Staphylococcus aureus isolated from fresh porcine skin xenografts: Risk to recipients with thermal injury

The previous use of fresh porcine xenografts at the Prague Burn Centre had raised concerns over the transmission of zoonotic pathogens. This study examines the risk of zoonotic Staphylococcus aureus colonisation of burn patients from fresh porcine skin xenografts.Samples were collected from the nares, skin and perineum of commercial pigs (n=101) and were screened for methicillin sensitive S. aureus (MSSA) and resistant S. aureus (MRSA). The efficacy of the antibiotic wash used in decontamination of the pigskin was tested against planktonic- and biofilm-grown isolates. The spa type of each isolate was also confirmed.All pig swabs were negative for MRSA but 86% positive for MSSA. All planktonic-grown isolates of MSSA were sensitive to chloramphenicol and nitrofurantoin and 44% of isolates were resistant to streptomycin. Isolates grown as biofilm exhibited higher rates of antimicrobial resistance. Sequence analysis revealed three distinct spa types of the MRSA ST398 clonal type.This finding demonstrates the existence of a MSSA reservoir containing spa types resembling those of well-known MRSA strains. These MSSA exhibit resistance to antibiotics used for decontamination of the pigskin prior to xenograft. Amended use of procurement could allow the use of fresh pigskin xenografts to be reinstated.