Beyond HOSPEX: what is the additional training value of military hospital exercises (HOSPEX)?

BACKGROUND

The use of simulation in clinical environments is a frequently used adjunct to training individuals and teams. The military uses clinical simulation to train large numbers of personnel, standardise patient pathways and sustain specific skills to ensure medical personnel are prepared to deploy in their clinical roles.

METHODS

As part of a North Atlantic Treaty Organization (NATO) exercise, 256 Field Hospital (Reserves) deployed a team of clinicians to simulate a role 2 basic field hospital. This hospital exercise (HOSPEX) involved training, and a 4-day real-time exercise with casualty simulation. A retrospective survey of all clinical personnel was conducted to analyse the utility of the exercise on their understanding of their job role, the workings of the field hospital and their confidence in deploying on operations.

RESULTS

39 personnel were surveyed, with questions graded on a modified Likert scale. 41% had previous operational experience in their current job role. A significantly higher proportion of respondents graded their understanding of their job role, and the field hospital overall, as good or excellent having completed the exercise (p<0.01), and 90% felt more confident in fulfilling their operational role postexercise. 90% of respondents had previous experience of simulation, and 94% of these rated the military simulation as being more beneficial than civilian equivalents.

DISCUSSION

With a shift towards simulation in medical training, opportunities have arisen within HOSPEX to develop additional skills for teams and individuals. Simulation is especially important in personnel who have not had previous operational experience, who may deploy on first time operations in senior clinical and leadership roles.

CONCLUSION

HOSPEXs are perceived as being extremely useful by clinical personnel preparing for future operational deployment. HOSPEX simulation has prepared the military for varied operations since its inception, and the paradigm has potential for extension into civilian training for high intensity medical responses.

Increased permeability of reconstructed human epidermis from UVB-irradiated keratinocytes

Extrinsic (photo) aging accelerates chronologically aging in the skin due to cumulative UV irradiation. Despite recent insights into the molecular mechanisms of fibroblast aging, age-related changes of the skin barrier function have been understudied. In contrast, the constantly increasing subpopulation of aged patients causes a clinical need for effective and safe (dermatological) treatment. Herein, we reconstructed human epidermis from UVB-irradiated keratinocytes (UVB-RHE). UVB-irradiated keratinocytes show higher activity of senescence associated β-galactosidase, less cell proliferation, and reduced viability. Higher amounts of β-galactosidase are also detectable in UVB-RHE. Moreover, UVB-RHE release more interleukin-1α and -8 into the culture medium and present altered differentiation with a thinner stratum corneum compared to normal RHE. For the first time, the permeation of testosterone and caffeine through UVB-irradiated RHE indicate a clear influence of the UVB stress on the skin barrier function. Impaired barrier function was confirmed by the increased permeation of testosterone and caffeine as well as by the increased penetration of dendritic core-multishell nanocarriers into the constructs. Taken together, UVB-RHE emulate hallmarks of skin aging and might contribute to an improved non-clinical development of medicinal or cosmetic products.

Time-Resolved Fluorescence Spectroscopy and Fluorescence Lifetime Imaging Microscopy for Characterization of Dendritic Polymer Nanoparticles and Applications in Nanomedicine

The emerging field of nanomedicine provides new approaches for the diagnosis and treatment of diseases, for symptom relief and for monitoring of disease progression. One route of realizing this approach is through carefully constructed nanoparticles. Due to the small size inherent to the nanoparticles a proper characterization is not trivial. This review highlights the application of time-resolved fluorescence spectroscopy and fluorescence lifetime imaging microscopy (FLIM) for the analysis of nanoparticles, covering aspects ranging from molecular properties to particle detection in tissue samples. The latter technique is particularly important as FLIM allows for distinguishing of target molecules from the autofluorescent background and, due to the environmental sensitivity of the fluorescence lifetime, also offers insights into the local environment of the nanoparticle or its interactions with other biomolecules. Thus, these techniques offer highly suitable tools in the fields of particle development, such as organic chemistry, and in the fields of particle application, such as in experimental dermatology or pharmaceutical research.

Poly[acrylonitrile-co-(N-vinyl pyrrolidone)] nanoparticles - Composition-dependent skin penetration enhancement of a dye probe and biocompatibility

Nanoparticles can improve topical drug delivery: size, surface properties and flexibility of polymer nanoparticles are defining its interaction with the skin. Only few studies have explored skin penetration for one series of structurally related polymer particles with systematic alteration of material composition. Here, a series of rigid poly[acrylonitrile-co-(N-vinyl pyrrolidone)] model nanoparticles stably loaded with Nile Red or Rhodamin B, respectively, was comprehensively studied for biocompatibility and functionality. Surface properties were altered by varying the molar content of hydrophilic NVP from 0 to 24.1% and particle size ranged from 35 to 244nm. Whereas irritancy and genotoxicity were not revealed, lipophilic and hydrophilic nanoparticles taken up by keratinocytes affected cell viability. Skin absorption of the particles into viable skin ex vivo was studied using Nile Red as fluorescent probe. Whilst an intact stratum corneum efficiently prevented penetration, almost complete removal of the horny layer allowed nanoparticles of smaller size and hydrophilic particles to penetrate into viable epidermis and dermis. Hence, systematic variations of nanoparticle properties allows gaining insights into critical criteria for biocompatibility and functionality of novel nanocarriers for topical drug delivery and risks associated with environmental exposure.

Interactions of hyaluronic Acid with the skin and implications for the dermal delivery of biomacromolecules

Hyaluronic acid (HA) hydrogels are interesting delivery systems for topical applications. Besides moisturizing the skin and improving wound healing, HA facilitates topical drug absorption and is highly compatible with labile biomacromolecules. Hence, in this study we investigated the influence of HA hydrogels with different molecular weights (5 kDa, 100 kDa, 1 MDa) on the skin absorption of the model protein bovine serum albumin (BSA) using fluorescence lifetime imaging microscopy (FLIM). To elucidate the interactions of HA with the stratum corneum and the skin absorption of HA itself, we combined FLIM and Fourier-transform infrared (FTIR) spectroscopy. Our results revealed distinct formulation and skin-dependent effects. In barrier deficient (tape-stripped) skin, BSA alone penetrated into dermal layers. When BSA and HA were applied together, however, penetration was restricted to the epidermis. In normal skin, penetration enhancement of BSA into the epidermis was observed when applying low molecular weight HA (5 kDa). Fluorescence resonance energy transfer analysis indicated close interactions between HA and BSA under these conditions. FTIR spectroscopic analysis of HA interactions with stratum corneum constituents showed an α-helix to β-sheet interconversion of keratin in the stratum corneum, increased skin hydration, and intense interactions between 100 kDa HA and the skin lipids resulting in a more disordered arrangement of the latter. In conclusion, HA hydrogels restricted the delivery of biomacromolecules to the stratum corneum and viable epidermis in barrier deficient skin, and therefore seem to be potential topical drug vehicles. In contrast, HA acted as an enhancer for delivery in normal skin, probably mediated by a combination of cotransport, increased skin hydration, and modifications of the stratum corneum properties.

Overview about the localization of nanoparticles in tissue and cellular context by different imaging techniques

The increasing interest and recent developments in nanotechnology pose previously unparalleled challenges in understanding the effects of nanoparticles on living tissues. Despite significant progress in in vitro cell and tissue culture technologies, observations on particle distribution and tissue responses in whole organisms are still indispensable. In addition to a thorough understanding of complex tissue responses which is the domain of expert pathologists, the localization of particles at their sites of interaction with living structures is essential to complete the picture. In this review we will describe and compare different imaging techniques for localizing inorganic as well as organic nanoparticles in tissues, cells and subcellular compartments. The visualization techniques include well-established methods, such as standard light, fluorescence, transmission electron and scanning electron microscopy as well as more recent developments, such as light and electron microscopic autoradiography, fluorescence lifetime imaging, spectral imaging and linear unmixing, superresolution structured illumination, Raman microspectroscopy and X-ray microscopy. Importantly, all methodologies described allow for the simultaneous visualization of nanoparticles and evaluation of cell and tissue changes that are of prime interest for toxicopathologic studies. However, the different approaches vary in terms of applicability for specific particles, sensitivity, optical resolution, technical requirements and thus availability, and effects of labeling on particle properties. Specific bottle necks of each technology are discussed in detail. Interpretation of particle localization data from any of these techniques should therefore respect their specific merits and limitations as no single approach combines all desired properties.

Penetration of normal, damaged and diseased skin--an in vitro study on dendritic core-multishell nanotransporters

A growing intended or accidental exposure to nanoparticles asks for the elucidation of potential toxicity linked to the penetration of normal and lesional skin. We studied the skin penetration of dye-tagged dendritic core-multishell (CMS) nanotransporters and of Nile red loaded CMS nanotransporters using fluorescence microscopy. Normal and stripped human skin ex vivo as well as normal reconstructed human skin and in vitro skin disease models served as test platforms. Nile red was delivered rapidly into the viable epidermis and dermis of normal skin, whereas the highly flexible CMS nanotransporters remained solely in the stratum corneum after 6h but penetrated into deeper skin layers after 24h exposure. Fluorescence lifetime imaging microscopy proved a stable dye-tag and revealed striking nanotransporter-skin interactions. The viable layers of stripped skin were penetrated more efficiently by dye-tagged CMS nanotransporters and the cargo compared to normal skin. Normal reconstructed human skin reflected the penetration of Nile red and CMS nanotransporters in human skin and both, the non-hyperkeratotic non-melanoma skin cancer and hyperkeratotic peeling skin disease models come along with altered absorption in the skin diseases.

Nanodynamics of dendritic core-multishell nanocarriers

The molecular dynamics of polymeric nanocarriers is an important parameter for controlling the interaction of nanocarrier branches with cargo. Understanding the interplay of dendritic polymer dynamics, temperature, and cargo molecule interactions should provide valuable new insight for tailoring the dendritic architecture to specific needs in nanomedicine, drug, dye, and gene delivery. Here, we have investigated polyglycerol-based core-multishell (CMS) nanotransporters with incorporated Nile Red as a fluorescent drug mimetic and CMS nanotransporters with a covalently bound fluorophore (Indocarbocyanine) using fluorescence spectroscopy methods. From time-resolved fluorescence depolarization we have obtained the rotational diffusion dynamics of the incorporated dye, the nanocarrier, and its branches as a function of temperature. UV/vis and fluorescence lifetime measurements provided additional information on the local dye environment. Our results show a distribution of the cargo Nile Red within the nanotransporter shells that depends on solvent and temperature. In particular, we show that the flexibility of the polymer branches in the unimolecular state of the nanotransporter undergoes a temperature-dependent transition which correlates with a larger space for the mobility of the incorporated hydrophobic drug mimetic Nile Red and a higher probability of cargo-solvent interactions at temperatures above 31 °C. The measurements have further revealed that a loss of the cargo molecule Nile Red occurred neither upon dilution of the CMS nanotransporters nor upon heating. Thus, the unimolecular preloaded CMS nanotransporters retain their cargo and are capable to transport and respond to temperature, thereby fulfilling important requirements for biomedical applications.

Exploiting Fluorescence Lifetime Plasticity in FLIM: Target Molecule Localization in Cells and Tissues

The mechanisms of drug-receptor interactions and the controlled delivery of drugs via biodegradable and biocompatible nanoparticulate carriers are active research fields in nanomedicine. Many clinically used drugs target G-protein coupled receptors (GPCRs) due to the fact that signaling via GPCRs is crucial in physiological and pathological processes and thus central for the function of biological systems. In this letter, a fast and reliable ratiometric fluorescence lifetime imaging microscopy (rmFLIM) approach is described to analyze the distribution of protein-ligand complexes in the cellular context. Binding of the fluorescently labeled antagonist naloxone to the G-protein coupled μ-opioid receptor is used as an example. To show the broad applicability of the rmFLIM method, we extended this approach to investigate the distribution of polymer-based nanocarriers in histological liver sections.

The reconnaissance and siting of field hospitals

This paper describes the reconnaissance function for the siting of deployable field hospitals. It reports two levels of reconnaissance, theatre/operational and tactical. The paper describes the factors to be considered when conducting the reconnaissance and the format of the reconnaissance report.