The Adjunct Use of Platelet-Rich Plasma in Split-Thickness Skin Grafts: A Systematic Review.

OBJECTIVE: To summarize the available literature on platelet-rich plasma (PRP) as an adjunct to split-thickness skin graft (STSG) in an organized and easy-to-read format. These data may encourage surgeons to integrate PRP into their skin graft protocol. DATA SOURCES: The authors conducted a systematic search using the PubMed, Cochrane, and ClinicalTrials.gov databases for articles published from their respective inceptions to October 1, 2019, to identify relevant studies. STUDY SELECTION: A total of 629 articles were reviewed, and 5 were identified for inclusion in this study. The population of all studies was patients receiving an STSG to close a skin defect. DATA EXTRACTION: Articles were screened for the following outcome measures: graft take rates, edema or hematoma formation, instant adhesion of graft, healing time, length of hospital stay, scar hypertrophy, and frequency of dressing changes. DATA SYNTHESIS: The data were organized into two tables describing the studies and the selected outcome measures. CONCLUSIONS: The data suggest that PRP in STSG reduces healing time, length of hospital stay, and scarring and that it eliminates the need for sutures/staples. Further, these benefits may correlate with a decrease in overall expenditure. This systematic review suggests that further research on PRP and skin grafts is warranted.

Spatially Resolved Analytical Chemistry in Intact, Living Tissues.

Tissues are an exciting frontier for bioanalytical chemistry, one in which spatial distribution is just as important as total content. Intact tissue preserves the native cellular and molecular organization and the cell-cell contacts found in vivo. Live tissue, in particular, offers the potential to analyze dynamic events in a spatially resolved manner, leading to fundamental biological insights and translational discoveries. In this Perspective, we provide a tutorial on the four fundamental challenges for the bioanalytical chemist working in living tissue samples as well as best practices for mitigating them. The challenges include (i) the complexity of the sample matrix, which contributes myriad interfering species and causes nonspecific binding of reagents; (ii) hindered delivery and mixing; (iii) the need to maintain physiological conditions; and (iv) tissue reactivity. This framework is relevant to a variety of methods for spatially resolved chemical analysis, including optical imaging, inserted sensors and probes such as electrodes, and surface analyses such as sensing arrays. The discussion focuses primarily on ex vivo tissues, though many considerations are relevant in vivo as well. Our goal is to convey the exciting potential of analytical chemistry to contribute to understanding the functions of live, intact tissues.

The Role of Toluidine Blue in Mohs Micrographic Surgery: A Systematic Review.

Toluidine blue (TB) is a metachromatic dye used as a stain in frozen sections in Mohs micrographic surgery (MMS). The current literature on the use of TB is sparse and generally qualitative in nature. The aim of this systematic review was to summarize and evaluate the existing literature analyzing TB use in MMS. The PubMed and Cochrane databases were searched for relevant studies published before December 1, 2019. Studies that analyzed the use of TB in frozen sections applicable to MMS were included. A total of 25 articles were reviewed, of which 12 fit the inclusion criteria. Our analysis showed that TB may play an important role in the successful diagnosis and treatment of particular cutaneous tumors.

Nodules on the Anterior Neck Following Poly-L-lactic Acid Injection.

Poly-L-lactic acid (PLLA) is a synthetic biologic polymer that is suspended in solution and can be injected for soft-tissue augmentation. The most common adverse events generally are transient in nature, such as swelling, tenderness, pain, bruising, and bleeding. Persistent adverse events of PLLA primarily are papule and nodule formation. Injecting PLLA into the anterior neck is an off-label procedure and may cause a higher incidence of nodule formation.

Intravascular Basal Cell Carcinoma Hiding under a Keratoacanthoma.

A 79-year-old male presented for removal of what was proven to be a keratoacanthoma. Additional tissue removed deep to the initial lesion revealed intravascular basal cell carcinoma (BCC). Intravascular BCC is exceedingly rare with only 8 cases previously reported in the literature. Intravascular BCC may be associated with more aggressive subtypes. Intravascular infiltration is more common in metastatic BCC, but this finding may not imply causality. More data are required in order to determine prognostic implications of intravascular BCC and to develop a protocol for managing patients with this unique finding.

Spatially resolved measurement of dynamic glucose uptake in live ex vivo tissues.

Highly proliferative cells depend heavily on glycolysis as a source of energy and biological precursor molecules, and glucose uptake is a useful readout of this aspect of metabolic activity. Glucose uptake is commonly quantified by using flow cytometry for cell cultures and positron emission tomography for organs in vivo. However, methods to detect spatiotemporally resolved glucose uptake in intact tissues are far more limited, particularly those that can quantify changes in uptake over time in specific tissue regions and cell types. Using lymph node metabolism as a case study, we developed an optimized method to detect dynamic and spatially resolved glucose uptake in living tissue by combining ex vivo tissue slice culture with a fluorescent glucose analogue. Live slices of murine lymph node were treated with the glucose analogue 2-[N-(7-nitrobenz-2-oxa-1,3-dia-xol-4-yl)amino]-2-deoxyglucose (2-NBDG). Incubation parameters were optimized to differentiate glucose uptake in activated versus naïve lymphocytes. Regional glucose uptake could be imaged at both the tissue level, by widefield microscopy, and at the cellular level, by confocal microscopy. Furthermore, the glucose assay was readily multiplexed with live immunofluorescence labelling to generate maps of 2-NBDG uptake across tissue regions, revealing highest uptake in T cell-dense regions. The signal was predominantly intracellular and localized to lymphocytes rather than stromal cells. Finally, we demonstrated that the assay was repeatable in the same slices, and imaged the dynamic distribution of glucose uptake in response to ex vivo T cell stimulation for the first time. We anticipate that this method will serve as a broadly applicable, user-friendly platform to quantify dynamic metabolic activities in complex tissue microenvironments.

User-defined local stimulation of live tissue through a movable microfluidic port.

Many in vivo tissue responses begin locally, yet most in vitro stimuli are delivered globally. Microfluidics has a unique ability to provide focal stimulation to tissue samples with precise control over fluid location, flow rate, and composition. However, previous devices utilizing fixed ports beneath the tissue required manual alignment of the tissue over the ports, increasing the risk of mechanical damage. Here we present a novel microfluidic device that allows the user to define the location of fluid delivery to a living tissue slice without manipulating the tissue itself. The device utilized a two-component SlipChip design to create a mobile port beneath the tissue slice. A culture chamber perforated by an array of ports housed a tissue slice and was separated by a layer of fluorocarbon oil from a single delivery port, fed by a microfluidic channel in the movable layer below. We derived and validated a physical model, based on interfacial tension and flow resistance, to predict the conditions under which fluid delivery occurred without leakage into the gap between layers. Aqueous solution was delivered reproducibly to samples of tissue and gel, and the width of the delivery region was controlled primarily by convection. Tissue slice viability was not affected by stimulation on the device. As a proof-of-principle, we showed that live slices of lymph node tissue could be sequentially targeted for precise stimulation. In the future this device may serve as a platform to study the effects of fluid flow in tissues and to perform local drug screening.

Working Memory Systems in the Rat.

A fundamental feature of memory in humans is the ability to simultaneously work with multiple types of information using independent memory systems. Working memory is conceptualized as two independent memory systems under executive control [1, 2]. Although there is a long history of using the term "working memory" to describe short-term memory in animals, it is not known whether multiple, independent memory systems exist in nonhumans. Here, we used two established short-term memory approaches to test the hypothesis that spatial and olfactory memory operate as independent working memory resources in the rat. In the olfactory memory task, rats chose a novel odor from a gradually incrementing set of old odors [3]. In the spatial memory task, rats searched for a depleting food source at multiple locations [4]. We presented rats with information to hold in memory in one domain (e.g., olfactory) while adding a memory load in the other domain (e.g., spatial). Control conditions equated the retention interval delay without adding a second memory load. In a further experiment, we used proactive interference [5-7] in the spatial domain to compromise spatial memory and evaluated the impact of adding an olfactory memory load. Olfactory and spatial memory are resistant to interference from the addition of a memory load in the other domain. Our data suggest that olfactory and spatial memory draw on independent working memory systems in the rat.