Challenges in fingertip replantation.
Ontology highlight
ABSTRACT:
SUBMITTER: Kim JS
PROVIDER: S-EPMC3842354 | biostudies-other | 2013 Nov
REPOSITORIES: biostudies-other
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Project description:Surgical ingenuity has resulted in continuing microsurgical innovation in replantation. In this article, the authors define complex amputations as those that stretch the boundaries or fall outside traditionally defined indications for replantation. They discuss management of difficult situations involving multiple digit amputations, multiple-level amputations, prolonged ischemia, and multiple trauma. The role of transpositional and ectopic replantation, as well as the requirement for secondary procedures in replantation is also discussed. Although technically challenging, microsurgical management of complex amputations ultimately results in far superior outcomes.
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Project description:In the early period of replantation surgery, the emphasis was on digit survival. Subsequently, with better microsurgical techniques and instrumentation, the focus has shifted to function and in recent years to consideration of cost-effectiveness. Despite over 40 years of effort in refining digital replantation surgery, a rigorous evaluation of the outcomes of digital replantation has not been performed. This is because of the many confounding variables that influence outcome comparisons. These variables include the mechanism of injury (guillotine, crush, avulsion), the injury itself (total, near total, subtotal, partial amputation), and the surgical procedure (replantation, revascularization). In addition, the traditional outcome measures (two-point discrimination, range of motion, grip strength, or the ability to return to work) are reported inconsistently and vary widely among publications. All these factors make meaningful comparison of outcomes difficult. The recent emphasis on outcome research and cost-effectiveness necessitates a rethinking in the way we report outcomes of digital replantation. In this article, the authors summarize the challenges in assessing outcomes of digital replantation and explain the need to measure outcomes using rigorous clinical research designs that incorporate cost-effectiveness studies in the research protocol.
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Project description:Objective: This study aimed to identify the transcriptome profiles from periodontal tissues of replanted teeth and evaluate the functional differences of transcriptomes between immediate replantation and delayed replantation in a rat teeth avulsion animal model. Background: In dental avulsion, the prognosis of replanted teeth is hardly favorable in delayed replantation. After tooth replantation, complex inflammatory responses occur to return homeostasis in periodontal tissue. Various types of cytokines are produced in inflammatory microenvironment and these cytokines determine the periodontal tissue responses. Methods: Maxillary first molars of Sprague–Dawley rats were extracted and exposed to dry environment, then replanted. The animals were divided into two groups according to extra–oral time: immediate replantation group (dry for 5 min) and delayed replantation (dry for 60 min). Either 3 or 7 days after replantation, the animals were sacrificed. The palatal gingival tissues were harvested for mRNA–sequencing. Hallmark gene set enrichment analysis were performed to predict the function of transcriptomes. Normalized enrichment score (NES) was generated to determine the functional differences between the groups. Results: Hallmark gene sets enriched in delayed replantation at 3 days were oxidative phosphorylation (NES=2.82, q < 0.001) and TNF–α signaling via NF–κB pathway (NES= 1.52, q=0.034). At 7 days, TNF–α signaling via NF–κB pathway (NES=–1.82, q=0.002), angiogenesis (NES=–1.66, q =0.01), and TGF–β signaling pathway (NES=–1.46, q=0.051) were negatively highlighted in delayed replantation compared to immediate replantation. Conclusions: Transcriptome profiles were significantly different between immediate replantation and delayed replantation. The responses of periodontal tissues were associated with TNF–α signaling via NF–κB pathway. However, the enrichment score of this pathway were changed with time–dependent manner between immediate replantation and delayed replantation.
2021-05-01 | GSE173622 | GEO
Project description:Human fingertip microflora is transferred to touched objects and may provide forensically relevant information on individual hosts, such as on geographic origins, if endogenous microbial skin species/strains would be retrievable from physical fingerprints and would carry geographically restricted DNA diversity. We tested the suitability of physical fingerprints for revealing human host information, with geographic inference as example, via microbial DNA fingerprinting. We showed that the transient exogenous fingertip microflora is frequently different from the resident endogenous bacteria of the same individuals. In only 54% of the experiments, the DNA analysis of the transient fingertip microflora allowed the detection of defined, but often not the major, elements of the resident microflora. Although we found microbial persistency in certain individuals, time-wise variation of transient and resident microflora within individuals was also observed when resampling fingerprints after 3 weeks. While microbial species differed considerably in their frequency spectrum between fingerprint samples from volunteers in Europe and southern Asia, there was no clear geographic distinction between Staphylococcus strains in a cluster analysis, although bacterial genotypes did not overlap between both continental regions. Our results, though limited in quantity, clearly demonstrate that the dynamic fingerprint microflora challenges human host inferences for forensic purposes including geographic ones. Overall, our results suggest that human fingerprint microflora is too dynamic to allow for forensic marker developments for retrieving human information.
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Project description:Multi-sensory human-machine interfaces are currently challenged by the lack of effective, comfortable and affordable actuation technologies for wearable tactile displays of softness in virtual- or augmented-reality environments. They should provide fingertips with tactile feedback mimicking the tactual feeling perceived while touching soft objects, for applications like virtual reality-based training, tele-rehabilitation, tele-manipulation, tele-presence, etc. Displaying a virtual softness on a fingertip requires the application of quasi-static (non-vibratory) forces via a deformable surface, to control both the contact area and the indentation depth of the skin. The state of the art does not offer wearable devices that can combine simple structure, low weight, low size and electrically safe operation. As a result, wearable softness displays are still missing for real-life uses. Here, we present a technology based on fingertip-mounted small deformable chambers, which weight about 3 g and are pneumatically driven by a compact and cost-effective unit. Weighting less than 400 g, the driving unit is easily portable and can be digitally controlled to stimulate up to three fingertips independently. Psychophysical tests proved ability to generate useful perceptions, with a Just Noticeable Difference characterised by a Weber constant of 0.15. The system was made of off-the-shelf materials and components, without any special manufacturing process, and is fully disclosed, providing schematics and lists of components. This was aimed at making it easily and freely usable, so as to turn tactile displays of softness on fingertips into a technology 'at fingertips'.
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Project description:Most literature on fingertips reviews new surgical techniques of coverage while many surgeons prefer the results of secondary healing. This article reviews the current best evidence and concepts about secondary healing in fingertip injuries.
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Project description:Amputations of a traumatic origin are very frequent in developing countries, in the case of Guatemala these are a result of work accidents very closely related to poor work conditions existing for manual workers, as well as social violence and the lack of security that governs society. The present case shows a patient that suffered a left hand amputation at wrist level. Amputated hand was transported swiftly and in adequate conditions, maintaining cold chain at all times until arrival at Hospital for replantation. After 14 months, patient has evolved satisfactorily and obtained functional result of the hand.
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Project description:When touched, a glass plate excited with ultrasonic transverse waves feels notably more slippery than it does at rest. To study this phenomenon, we use frustrated total internal reflection to image the asperities of the skin that are in intimate contact with a glass plate. We observed that the load at the interface is shared between the elastic compression of the asperities of the skin and a squeeze film of air. Stroboscopic investigation reveals that the time evolution of the interfacial gap is partially out of phase with the plate vibration. Taken together, these results suggest that the skin bounces against the vibrating plate but that the bounces are cushioned by a squeeze film of air that does not have time to escape the interfacial separation. This behavior results in dynamic levitation, in which the average number of asperities in intimate contact is reduced, thereby reducing friction. This improved understanding of the physics of friction reduction provides key guidelines for designing interfaces that can dynamically modulate friction with soft materials and biological tissues, such as human fingertips.
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Project description:The success of replantation surgery is not judged by survival of the replanted part, but by the functional outcome attained. Hence, primary repair of all injured structures is the preferred aim. At times, constraints induced by the ischemia time and nature of injury preclude primary repair. In such situations, secondary procedures are inevitable. Secondary procedures are also frequently required to improve the function and appearance of the replanted extremity. The incidence of secondary procedures will vary with the level of replantation and the type of patient population. Secondary procedures are difficult because they carry risk of injury to the vital neurovascular structures that now lay at nonanatomical locations. Nevertheless, when indicated and performed with caution they could significantly raise the functional status of the individuals.
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Project description:The temporal evolution of surface strain, resulting from a combination of normal and tangential loading forces on the fingerpad, was calculated from high-resolution images. A customized robotic device loaded the fingertip with varying normal force, tangential direction and tangential speed. We observed strain waves that propagated from the periphery to the centre of the contact area. Consequently, different regions of the contact area were subject to varying degrees of compression, stretch and shear. The spatial distribution of both the strains and the strain energy densities depended on the stimulus direction. Additionally, the strains varied with the normal force level and were substantial, e.g. peak strains of 50% with a normal force of 5 N, i.e. at force levels well within the range of common dexterous manipulation tasks. While these observations were consistent with some theoretical predictions from contact mechanics, we also observed substantial deviations as expected given the complex geometry and mechanics of fingertips. Specifically, from in-depth analyses, we conclude that some of these deviations depend on local fingerprint patterns. Our data provide useful information for models of tactile afferent responses and background for the design of novel haptic interfaces.
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