Distal Limb Research Articles

Regulation of LIM homeodomain 2 (Lhx2) in the distal limb bud during patterning and development

During limb morphogenesis, fibroblast growth factors (Fgfs) secreted from the apical ectodermal ridge (AER) direct proximodistal outgrowth of the limb, while sonic hedgehog (Shh) released from the zone of polarizing activity modulate anteroposterior expansion of the limb. Fgfs and Shh maintain each other’s expression through an autoregulatory loop. The transcription factor LIM homeodomain 2 (Lhx2) is expressed in the distal sub‐AER mesoderm and is important for Shh expression. We have identified a chicken enhancer upstream of the LHX2 promoter that is active in the distal sub‐AER LHX2 expression domain that contains putative transcription factor binding sites for known downstream targets of FGF signaling that are critical for activity. Therefore, we hypothesized that LASARM1 interacts with the LHX2 promoter and that FGF works through LASARM1 to regulate LHX2 expression. To determine this, we performed chromosome conformation capture (3C) on cells isolated from distal chicken limb buds and compared them to non‐LHX2 expressing tail cells. Promoter and enhancer specific primers were used to isolate ligated promoter‐enhancer fragments by end‐point PCR. Amplified sequences were then sequence validated. A 3C ligation product library was used as a control. We also evaluated the role of FGF to regulate LASARM1 activity in subAER mesoderm by analyzing LASARM1 activity following inhibition of FGF signaling by an FGF‐receptor inhibitor. End‐point PCR revealed promoter‐enhancer ligated amplicons in distal limb bud cells, but not in tail cells. DNA sequencing of enhancer‐ligated fragments confirmed LHX2‐LASARM1 fusion fragments for distal limb bud cells. Interestingly, disruption of FGF signaling via a specific FGF receptor inhibitor did not alter LASARM1 activity, although LHX2 expression was markedly reduced. These findings suggest that LASARM1 interacts with the LHX2 promoter during limb patterning, but additional enhancers are required to mediate the FGF‐mediated up‐regulation of LHX2. Evaluation of additional LHX2 enhancers is underway. Investigations regarding the relationship between FGF and LHX2 will provide important insights into the mechanisms underlying LHX2 regulation and the FGF‐to‐SHH reciprocal loop.

Differential Regulation of Lhx9 Expression in Mouse and Chicken Limbs

The distal tip of the developing vertebrate limb is covered by a rim of thickened ectoderm called the apical ectodermal ridge (AER). The AER secretes fibroblast growth factors (Fgfs) into the underlying mesoderm to control outgrowth and proximal‐distal patterning. Patterning during outgrowth proceeds from proximal to distal, with the proximal segment or stylopod being laid down first, then the zeugopod, and the distal segment or autopod forming last. Secreted Fgfs from the AER maintain a sub‐AER population of undifferentiated mesoderm, called the progress zone, that provides cells for this progressive differentiation.In mice, Lhx9and its homologue Lhx2are expressed in the sub‐AER mesoderm and appear to play redundant roles in maintaining the expression of other patterning molecules, such as Shh. Interestingly in the chicken, the expression of LHX9 is restricted to the anterior aspect of the sub‐AER mesoderm, while LHX2 retains the full distal expression seen in mice. Recent clinical reports of an LHX9 missense mutation in a patient with hypoplastic/missing thumbs and great toes suggest that LHX9 can play a critical role in normal limb development. We hypothesized that the chicken cis‐regulatory modules (CRMs) regulating Lhx9 might have subtle species‐specific sequence variations compared to the murine CRMs that correlate with this differential expression pattern.To test this hypothesis, potential CRMs were identified near the Lhx9 locus by in silicoanalysis, using sequence conservation and regulatory chromatin markers from published ChIP‐seq data. The potential CRMs were isolated and inserted into CRM‐reporter constructs. The limb‐related activity of a potential CRM was then determined by targeted regional electroporation into the distal chicken limb mesoderm.We identified a highly conserved, transcription‐factor‐rich 623 bp sequence within intron 12 of DENDD1B 132 kbp upstream of the chicken LHX9 transcription start site. The potential CRM was associated with H3k4me2, H3k27ac, p300 and H3k27me3. The associated CRM‐reporter construct displayed activity in both anterior and posterior sub‐AER limb mesoderm overlapping LHX9 and LHX2 expression. These findings are consistent with a distal sub‐AER LHX9enhancer, but do not account for the lack of posterior expression. This suggests that additional CRMs contribute to the final expression pattern of LHX9 in the limb. Twenty‐two additional potential CRMs were identified and will be further characterized to determine their role in restricting LHX9expression from the posterior mesoderm in chickens. Characterizing the differential regulation of Lhx9 during limb development may provide insight into the species‐specific variation of limb patterning.

An E‐Box Binding Site is Sufficient for ZPA Regulatory Sequence (ZRS) Activity in the Limb

The zone of polarizing activity (ZPA) is a cluster of mesodermal cells that secrete Sonic hedgehog (Shh) to regulate anterior‐posterior patterning during limb development. The ZPA regulatory sequence (ZRS) is the limb‐specific enhancer that controls Shh expression. ZRS microdeletion abrogates Shh expression and posterior limb development, whereas ZRS single nucleotide variants (SNVs) produce anterior ectopic Shh and preaxial polydactyly. However, the ZRS mechanism of action is not well characterized. Transcription factors (TFs) Hand2, Twist1, and Hoxd13 regulate Shh expression and ZRS contains putative binding sites for each: two Hoxd13 binding sites and three E‐boxes, sites targeted by basic helix‐loop‐helix (bHLH) TFs such as Hand2 and Twist1. Further, reports suggest these TFs may act through the ZRS: Hand2 purportedly binds the ZRS through a central E‐box; as bHLH‐TFs Hand2 and Twist1 may regulate ZRS as homo‐ or heterodimers; and both Hand2 and Hoxd13 activate the ZRS in vitro. Previously we demonstrated that disrupting all five binding sites eliminates ZRS activity. In this report, we further investigate these sites to determine the contribution of each to ZRS activity. We hypothesized that the Hand2 binding site is required for activity and that other E‐boxes and Hoxd13 sites localize ZRS activity to the distal posterior limb mesoderm.We assessed ZRS activity via an enhancer‐GFP reporter, altering all five binding sites to eliminate activity, then reinstating each site individually using site‐directed mutagenesis. Constructs were electroporated into the presumptive limbs of chicken embryos (Hamburger‐Hamilton stage 14). Enhancer activity was evaluated 48 hours post‐electroporation by fluorescence microscopy. Restoring either Hoxd13 site led to weak, focal activity. Restoring two of the E‐boxes had little to no effect, however, restoring the third, 3’ E‐box was sufficient for robust activity. This was unexpected since the central E‐box was reported as the likely Hand2 binding site. Our data suggest that the 3’ E‐box is likely the critical site used by Hand2 in ZRS‐mediated Shh regulation. Additionally, the Hoxd13 binding sites appear to impart focal activity supporting a role for localization. These findings further characterize the mechanism used to regulate focal Shh expression during limb development.

Normal embryonic development and neonatal digit regeneration in mice overexpressing a stem cell factor, Sall4.

Sall4 encodes a transcription factor and is known to participate in the pluripotency network of embryonic stem cells. Sall4 expression is known to be high in early stage post-implantation mouse embryos. During early post-gastrulation stages, Sall4 is highly expressed in the tail bud and distal limb buds, where progenitor cells are maintained in an undifferentiated status. The expression of Sall4 is rapidly downregulated during embryonic development. We previously demonstrated that Sall4 is required for limb and posterior axial skeleton development by conditional deletion of Sall4 in the T (Brachyury) lineage. To gain insight into Sall4 functions in embryonic development and postnatal digit regeneration, we genetically overexpressed Sall4 in the mesodermal lineage by the TCre transgene and a novel knockin allele of Rosa26-loxP-stop-loxP-Sall4. In significant contrast to severe defects by Sall4 loss of function reported in previous studies, overexpression of Sall4 resulted in normal morphology and pattern in embryos and neonates. The length of limb long bones showed subtle reduction in Sall4-overexpression mice. It is known that the digit tip of neonatal mice has level-specific regenerative ability after experimental amputation. We observed Sall4 expression in the digit tip by using a sensitive Sall4-LacZ knock-in reporter expression. Sall4 overexpression did not alter the regenerative ability of the terminal phalange that normally regenerates after amputation. Moreover, Sall4 overexpression did not confer regenerative ability to the second phalange that normally does not regenerate after amputation. These genetic experiments show that overexpression of Sall4 does not alter the development of the appendicular and axial skeleton, or neonatal digit regeneration. The results suggest that Sall4 acts as a permissive factor rather than playing an instructive role.

Distal Radial Artery Ligation for Dialysis Access Steal Syndrome

Renal replacement therapy is the definitive treatment for end stage renal disease apart from transplant. Steal syndrome, which can lead to distal limb ischemia, is a rare but serious complication in patients who undergo hemodialysis with an arteriovenous fistula. We present a case of a 48-year-old female with limited options for dialysis access who presented with symptoms of steal syndrome. Given the need to keep her current fistula, we opted to treat her with distal radial artery ligation. This case report summarizes the various surgical techniques available for treating dialysis access-associated steal syndrome and why distal radial artery ligation should be considered a viable management strategy, especially in the context of our patient.

Flexor digitorum brevis utilizes elastic strain energy to contribute to both work generation and energy absorption at the foot.

ABSTRACTThe central nervous system utilizes tendon compliance of the intrinsic foot muscles to aid the foot's arch spring, storing and returning energy in its tendinous tissues. Recently, the intrinsic foot muscles have been shown to adapt their energetic contributions during a variety of locomotor tasks to fulfil centre of mass work demands. However, the mechanism by which the small intrinsic foot muscles are able to make versatile energetic contributions remains unknown. Therefore, we examined the muscle–tendon dynamics of the flexor digitorum brevis during stepping, jumping and landing tasks to see whether the central nervous system regulates muscle activation magnitude and timing to enable energy storage and return to enhance energetic contributions. In step-ups and jumps, energy was stored in the tendinous tissue during arch compression; during arch recoil, the fascicles shortened at a slower rate than the tendinous tissues while the foot generated energy. In step-downs and landings, the tendinous tissues elongated more and at greater rates than the fascicles during arch compression while the foot absorbed energy. These results indicate that the central nervous system utilizes arch compression to store elastic energy in the tendinous tissues of the intrinsic foot muscles to add or remove mechanical energy when the body accelerates or decelerates. This study provides evidence for an adaptive mechanism to enable the foot's energetic versatility and further indicates the value of tendon compliance in distal lower limb muscle–tendon units in locomotion.

Novel biallelic variants affecting the OTU domain of the gene OTUD6B associate with severe intellectual disability syndrome and molecular dynamics simulations

Intellectual developmental disorder with dysmorphic facies, seizures, and distal limb anomalies (IDDFSDA) is an autosomal recessive multisystem disorder caused by compound heterozygous or homozygous variants in the gene OTUD6B. Herein, we describe novel pathogenic compound heterozygous variants in OTUD6B identified via whole-exome sequencing in an index case exhibited the severe IDDFSDA phenotype. The potential pathogenicity of the novel frameshift and missense variants in the index case was investigated using in silico tools. The truncating frameshift variant in one allele was predicted to undergo degradation via nonsense-mediated decay of the mRNA molecule. To predict the severity of the damage to the protein caused by the missense variant in the other allele and its effects on phenotypic severity was further investigated together with a previously reported first homozygous missense variant in the same domain in another patient with a less severe IDDFSDA phenotype using structural modeling and molecular dynamics (MD) simulations for the first time. Based on these analyzes, it is anticipated that Tyr216Cys in the earlier reported case with less severe IDDFSDA will lead to localized destabilization, whereas Ile274Arg in the presented index case with the severe IDDFSDA phenotype will lead to significant distortion in the overall fold of OTUD6B. Our findings suggest that compound LOF and ultrarare missense variants may be contribute to the underlying variability expressivity associated with this disorder. In conclusion, our findings support that the clinical severity could be related with the predicted functional severity of the variations in OTUD6B. However, additional functional studies are required.

Relationship between Trunk Performance and the Stair Ascending and Descending in Post Stroke Subjects

Purpose and Objective:- Trunk being the central keypoint of the body, good trunk stability is essential for reaching and grasping and proximal trunk control is a prerequisite for distal lower limb movement control in functional activities like walking and stair climbing. There are several clinical tools to measure trunk performance such as The sitting balance item of the Motor assessment scale, The trunk control test, leg and trunk scale of the Rivermead Motor Assessment Scale. The Trunk Impairment Scale (TIS) a new tool to measure motor impairment of trunk after stroke was developed in 2004 by G Verheyden et al. Studies were conducted to correlate the TIS with Tinette, TUG test, 10 min walk test. However studies were not conducted to show the relationship between the trunk impairment and stair climbing in stroke subject. Design:- Correlational study Settings:-HOSMAT Hospital, BangaloreSubjects:-A total of 32 stroke subjects with a mean (SD) age of 53.90 ± 13.07 yrs. 21 males and 11 females participated.Method:-All the 32 subjects were administered with TIS and then followed by stair ascend and descend test. Outcome measures:- TIS, Stair ascend and descend test.Results:-The median scores of static, dynamic sitting balance and coordination ( 5, 6, 1) respectively. Mean score of stair ascend - 18.87±11.05 and for stair descend - 20.60±12.43.There was a moderate negative correlation between TIS and stair ascend with rs= -0.54 (P=0.001), moderate negative correlation between TIS and stair descend with rs=-0.63(P=0.001) and also moderate negative correlation between TIS and stair ascend + descend rs= 0.58(P=0.001).Conclusion:-The Trunk impairment scale shows moderate correlation with the stair ascend and descend test, which suggests that a person scoring less on the Trunk Impairment Scale (TIS ) takes more time to ascend and descend the stairs.

Effects of regional limb perfusion technique on concentrations of antibiotic achieved at the target site: A meta-analysis.

Intravenous regional limb perfusions (RLP) are widely used in equine medicine to treat distal limb infections, including synovial sepsis. RLPs are generally deemed successful if the peak antibiotic concentration (Cmax) in the sampled synovial structure is at least 8-10 times the minimum inhibitory concentration (MIC) for the bacteria of interest. Despite extensive experimentation and widespread clinical use, the optimal technique for performing a successful perfusion remains unclear. The objective of this meta-analysis was to examine the effect of technique on synovial concentrations of antibiotic and to assess under which conditions Cmax:MIC ≥ 10. A literature search including the terms "horse", "equine", and "regional limb perfusion" between 1990 and 2021 was performed. Cmax (μg/ml) and measures of dispersion were extracted from studies and Cmax:MIC was calculated for sensitive and resistant bacteria. Variables included in the analysis included synovial structure sampled, antibiotic dose, tourniquet location, tourniquet duration, general anesthesia versus standing sedation, perfusate volume, tourniquet type, and the concurrent use of local analgesia. Mixed effects meta-regression was performed, and variables significantly associated with the outcome on univariable analysis were added to a multivariable meta-regression model in a step-wise manner. Sensitivity analyses were performed to assess the robustness of our findings. Thirty-six studies with 123 arms (permutations of dose, route, location and timing) were included. Cmax:MIC ranged from 1 to 348 for sensitive bacteria and 0.25 to 87 for resistant bacteria, with mean (SD) time to peak concentration (Tmax) of 29.0 (8.8) minutes. Meta-analyses generated summary values (θ) of 42.8 x MIC and 10.7 x MIC for susceptible and resistant bacteria, respectively, though because of high heterogeneity among studies (I2 = 98.8), these summary variables were not considered reliable. Meta-regression showed that the only variables for which there were statistically significant differences in outcome were the type of tourniquet and the concurrent use of local analgesia: perfusions performed with a wide rubber tourniquet and perfusions performed with the addition of local analgesia achieved significantly greater concentrations of antibiotic. The majority of arms achieved Cmax:MIC ≥ 10 for sensitive bacteria but not resistant bacteria. Our results suggest that wide rubber tourniquets and concurrent local analgesia should be strongly considered for use in RLP and that adequate therapeutic concentrations (Cmax:MIC ≥ 10) are often achieved across a variety of techniques for susceptible but not resistant pathogens.

De novo variants in ATP2B1 lead to neurodevelopmental delay

Calcium (Ca2+) is a universal second messenger involved in synaptogenesis and cell survival; consequently, its regulation is important for neurons. ATPase plasma membrane Ca2+ transporting 1 (ATP2B1) belongs to the family of ATP-driven calmodulin-dependent Ca2+ pumps that participate in the regulation of intracellular free Ca2+. Here, we clinically describe a cohort of 12 unrelated individuals with variants in ATP2B1 and an overlapping phenotype of mild to moderate global development delay. Additional common symptoms include autism, seizures, and distal limb abnormalities. Nine probands harbor missense variants, seven of which were in specific functional domains, and three individuals have nonsense variants. 3D structural protein modeling suggested that the variants have a destabilizing effect on the protein. We performed Ca2+ imaging after introducing all nine missense variants in transfected HEK293 cells and showed that all variants lead to a significant decrease in Ca2+ export capacity compared with the wild-type construct, thus proving their pathogenicity. Furthermore, we observed for the same variant set an incorrect intracellular localization of ATP2B1. The genetic findings and the overlapping phenotype of the probands as well as the functional analyses imply that de novo variants in ATP2B1 lead to a monogenic form of neurodevelopmental disorder.

Parallel Cross-Leg Free Flap with Posterior Tibial Artery Perforator Pedicle Propeller Cable Bridge Flap for the Treatment of Lower Extremity Wounds: A Case Series Report

Background A cross-leg flap can be used to treat severely injured lower limbs but associated with complications. Herein, we describe a technique of a parallel cross-leg free flap combined with posterior tibial artery perforator pedicle propeller cable bridge flap for the treatment of lower extremity wounds. Methods The artery and veins of the free flap are anastomosed to the contralateral posterior tibial artery and vein, respectively. The vascular pedicle is wrapped with a posterior tibial artery perforator pedicle propeller flap. The legs are allowed to remain in a straight, relaxed position which is maintained with a bandage or Kirschner wire placed at the distal limbs. Pedicle division is performed around 21 days after flap creation, and the posterior artery is re-anastomosed and pedicled flap returned to its original position. Results From June 2017 to March 2020, 7 patients with lower extremity wounds and tissue loss received reconstruction with this method. The recipient vessels for all flaps were the posterior tibial artery and vein. The average operation time was 5 hours. The average time to ambulation was 4 weeks, and the average follow-up time was 13.7 months. All flaps survived, and limb salvage was successful in all patients. Patients were not uncomfortable with the limbs held in position until pedicle division, and there were no complications. At the final follow-up, the function of all limbs was normal, and the esthetic appearance was acceptable to all patients. Conclusions The method described overcomes the disadvantages of traditional cross-leg flaps for the treatment.

Mycobacterium leprae induces Schwann cell proliferation and migration in a denervated milieu following intracutaneous excision axotomy in nine-banded armadillos

Nine–banded armadillos develop peripheral neuropathy after experimental Mycobacterium leprae infection that recapitulates human disease. We used an intracutaneous excision axotomy model to assess the effect of infection duration by M. leprae on axonal sprouting and Schwan cell density.34 armadillos (17 naïve and 17 M. leprae-infected) underwent 3 mm skin biopsies to create an intracutaneous excision axotomy followed by a concentric 4-mm overlapping biopsy 3 and 12-months post M. leprae inoculation. A traditional distal leg biopsy was obtained at 15mo for intraepidermal nerve fiber (IENF) density. Serial skin sections were immunostained against a axons (PGP9.5, GAP43), and Schwann cells (p75, s100) to visualize regenerating nerves. Regenerative axons and proliferation of Schwann cells was measured and the rate of growth at each time point was assessed. Increasing anti-PGL antibody titers and intraneural M. leprae confirmed infection.15mo following infection, there was evidence of axon loss with reduced distal leg IENF versus naïve armadillos, p < 0.05. This was associated with an increase in Schwann cell density (11,062 ± 2905 vs. 7561 ± 2715 cells/mm3, p < 0.01). Following excisional biopsy epidermal reinnervation increased monotonically at 30, 60 and 90 days; the regeneration rate was highest at 30 days, and decreased at 60 and 90 days. The reinnervation rate was highest among animals infected for 3mo vs those infected for 12mo or naïve animals (mean ± SD, 27.8 ± 7.2 vs.16.2 ± 5.8vs. 15.3 ± 6.5 mm/mm3, p < 0.05). The infected armadillos displayed a sustained Schwann cell proliferation across axotomy time points and duration of infection (3mo:182 ± 26, 12mo: 256 ± 126, naive: 139 ± 49 cells/day, p < 0.05).M. leprae infection is associated with sustained Schwann cell proliferation and distal limb nerve fiber loss. Rates of epidermal reinnervation were highest 3mo after infection and normalized by 12 mo of infection. We postulate that excess Schwann cell proliferation is the main pathogenic process and is deleterious to sensory axons. There is a compensatory initial increase in regeneration rates that may be an attempt to compensate for the injury, but it is not sustained and eventually followed by axon loss. Aberrant Schwann cell proliferation may be a novel therapeutic target to interrupt the pathogenic cascade of M. leprae.

Cancer survivors post-chemotherapy exhibit unique proprioceptive deficits in proximal limbs

BackgroundOxaliplatin (OX) chemotherapy for colorectal cancer is associated with adverse neurotoxic effects that can contribute to long-term sensorimotor impairments in cancer survivors. It is often thought that the sensorimotor impairments are dominated by OX-induced dying-back sensory neuropathy that primarily affects the distal regions of the limb. Recent preclinical studies have identified encoding dysfunction of muscle proprioceptors as an alternative mechanism. Unlike the dying-back sensory neuropathy affecting distal limbs, dysfunction of muscle proprioceptors could have more widespread effects. Most investigations of chemotherapy-induced sensorimotor impairments have considered only the effects of distal changes in sensory processing; none have evaluated proximal changes or their influence on function. Our study fills this gap by evaluating the functional use of proprioception in the shoulder and elbow joints of cancer survivors post OX chemotherapy. We implemented three multidirectional sensorimotor tasks: force matching, target reaching, and postural stability tasks to evaluate various aspects of proprioception and their use. Force and kinematic data of the sensorimotor tasks were collected in 13 cancer survivors treated with OX and 13 age-matched healthy controls.ResultsCancer survivors exhibited less accuracy and precision than an age-matched control group when they had to rely only on proprioceptive information to match force, even for forces that required only torques about the shoulder. There were also small differences in the ability to maintain arm posture but no significant differences in reaching. The force deficits in cancer survivors were significantly correlated with self-reported motor dysfunction.ConclusionsThese results suggest that cancer survivors post OX chemotherapy exhibit proximal proprioceptive deficits, and that the deficits in producing accurate and precise forces are larger than those for producing unloaded movements. Current clinical assessments of chemotherapy-related sensorimotor dysfunction are largely limited to distal symptoms. Our study suggests that we also need to consider changes in proximal function. Force matching tasks similar to those used here could provide a clinically meaningful approach to quantifying OX-related movement dysfunction during and after chemotherapy.

756 Self-Inflicted Frostbite with Dry Ice: A Case Report

IntroductionFrostbite (FB) is a severe form of cold injury that may result in significant morbidity. Freezing causes formation of ice crystals and protein denaturation leading to cellular damage and tissue necrosis. Although commonly affecting populations who live and work or become stranded in cold environments, the true prevalence is unknown due to lack of standardized reporting. Dry ice is a solid form of carbon dioxide commonly found in the food industry, that can reach temperatures as cold as -110 degrees Fahrenheit and can be purchased at local department stores. Exposure to dry ice is an unusual cause of FB injury that could occur anywhere, especially in warmer climates. Healthcare professionals practicing in warmer climates may be unprepared to assess and treat patients with such injuries.MethodsWe describe a case of self-inflicted FB injury to the bilateral lower extremities (BLE) following intentional submersion in dry ice who presented to a Southern U.S. Burn Unit.ResultsA 20-year-old man with self-diagnosed Body Integrity Identity Disorder (BIID) sustained a 12% TBSA FB injury to his BLE following intentional submersion in dry ice for an estimated 4 hours (Figure 1). He presented to the Burn Center from an outside facility approximately 12 hours post injury with initial rewarming having already occurred. He immediately underwent catheter directed intra-arterial thrombolysis with tissue plasminogen activator (TPA) for leg length preservation. TPA infusion was initiated at 16 hours post-injury for a total infusion time of 24 hours. Wound care consisted of gentle twice daily cleansing with silver sulfadiazine and mafenide acetate creams. The patient ultimately required bilateral below the knee amputations which successfully healed with minimal autografting to the distal limbs. He was formally diagnosed with schizophrenia by our behavioral health team and initiated on risperidone. He underwent aggressive physical therapy and was discharged home with his parents after 21 days. He underwent weekly mental health follow up appointments and has been seen regularly in our burn and rehabilitation clinic.ConclusionsThis unusual case is one of few to describe Grade 4 FB after exposure to dry ice and highlights that severe FB may occur in any climate and can cause severe morbidity. Severe cold injury management is important for burn care professionals to maximize tissue and limb preservation.

Post-traumatic and non-traumatic Complex Regional Pain Syndrome type I

Complex regional pain syndrome (CRPS) is an umbrella term covering different clinical scenarios. It is a rare condition characterized by regional persisting pain, disproportionate to its underlying cause, usually coupled with sensorimotor, vasomotor, sudomotor, and trophic abnormalities. Different forms of CRPS have been identified: CRPS type I (algodystrophy); CRPS type II (causalgia); CRPS-NOS (not otherwise specified), and CRPS with remission of some features (CRSF). The pathophysiology of algodystrophy is probably related to multiple mechanisms, such as abnormal inflammation, vasomotor dysfunction, and maladaptive neuroplasticity. In most cases this condition is related to traumatic injuries or fractures, most frequently located at the distal upper limb, although in some patients no related triggering factor can be found. Algodystrophy occurrence after non-orthopedic surgery or procedures, such as percutaneous transluminal coronary angioplasty, cardiac ablation, hemodialysis, or transplantation, is rare and underestimated. Imaging can assist clinicians in the very challenging differential diagnosis of CRPS. To prevent severe and disabling consequences, international guidelines suggest a prompt multimodal approach to algodystrophy, including pharmacological (bisphosphonates, particularly neridronate) and non-pharmacological (i.e., rehabilitation interventions) measures.

Concentration of amikacin sulphate in synovial fluid when given in combination with dexamethasone phosphate in intravenous regional limb perfusion in standing horses.

Eight horses underwent IVRLP at two occasions through a 23-gauge 2cm long butterfly catheter. Regional anaesthesia of the ulnar, median and medial cutaneous antebrachial nerves was performed prior, and an 8cm rubber tourniquet was placed on the proximal radius for 30minutes following the infusion. The first infusion consisted of 2g of amikacin sulphate and 10mg of dexamethasone phosphate diluted with 0.9% NaCl to a total volume of 100ml. The second perfusion was performed after a 2-week washout period, the same protocol was used but without dexamethasone phosphate. Synovial fluid samples were collected from the metacarpophalangeal joint at T=0, 0.5, 2, 12, 24 and 36h post-infusion. Synovial fluid amikacin sulphate concentrations were determined by use of liquid chromatography/tandem mass-spectrometry. All horses (n=8) remained healthy throughout the study, and no adverse effects associated with the study were encountered. No statistically significant differences were found in synovial fluid amikacin sulphate concentrations between the treatment and the control group at any of the time points. In conclusion, dexamethasone phosphate can be used in IVRLP concomitantly with amikacin sulphate in cases of distal limb inflammation and pain without decreasing the synovial fluid concentration of amikacin sulphate.

Both Upper and Lower Limb Movements Contribute to Aesthetics of the Piqué Arabesque in Ballet.

This study aimed to identify the factor structures-which are the predominant frameworks for describing the basic dimensions of a concept-that contribute to the aesthetics of body position in ballet. This study was composed of three-dimensional movement analysis and subjective evaluation. Fourteen ballet dancers participated in the three-dimensional movement analysis. Thirty-six reflective markers were attached to the dancers' bodies, after which the dancers performed a piqué arabesque, a position in which the weight transfers from one leg to the other. This movement was captured using eight optical cameras and one video camera. Biomechanical parameters, such as the joint angle and velocity of each body part, were calculated from the coordinates of the markers. Twenty-eight videos recorded in the three-dimensional movement analysis were viewed by 51 observers with ballet experience. The observers subjectively evaluated the videos through four category pairs-"beautiful-ugly," "like-dislike," "interesting-not interesting," and "good-bad"-on a five-point semantic differential scale. Two groups, the top and bottom 30%, were extracted based on the "beautiful-ugly" rating and compared using an independent t-test. In addition, exploratory factor analysis was performed on the biomechanical parameters that showed significant differences. Five factors were identified: "stability of the right distal upper limb and upper body," "torso displacement speed," "stability of the left distal upper limb and line of the support leg," "height of the gesture leg," and "stability of the support leg around the hip joint and line of the limbs on the gesture leg side." These results indicate that the movements of both upper and lower limbs contributed to the aesthetics of the ballet position of piqué arabesque. These findings will be useful for ballet teachers and dancers to understand the intrinsic aesthetics of movements.

Extended resection for seizure control of pure motor strip focal cortical dysplasia during awake craniotomy: illustrative case.

BACKGROUNDFocal cortical dysplasias (FCD) represent highly intrinsically epileptogenic lesions that require complete resection for seizure control. Resection of pure motor strip FCD can be challenging. Effective control of postoperative seizures is crucial and extending the boundaries of resection in an eloquent zone remains controversial.OBSERVATIONSThe authors report a 52-year-old right-handed male with refractory epilepsy. The seizure phenotype was a focal crisis with preserved awareness and a clonic motor onset of right-hemibody. Epilepsy surgery protocol demonstrated a left pure motor strip FCD and a full-awake resective procedure with motor brain mapping was performed. Further resection of surgical boundaries monitoring function along intraoperative motor tasks with no direct electrical stimulation corroborated by intraoperative-neuromonitorization was completed as the final part of the surgery. In the follow-up period of 3-years, the patient has an Engel-IB seizure-control with mild distal lower limb palsy and no gate compromise.LESSONSThis report represents one of the few cases with pure motor strip FCD resection. In a scenario similar to this case, the authors consider that this variation can be useful to improve seizure control and the quality of life of these patients by extending the resection of a more extensive epileptogenic zone minimizing functional damage.

A novel heterozygous TPM2 gene mutation (c.456G>C; p.Lys152Asn) in an Iranian family affected by distal arthrogryposis type 1: a case report

BackgroundDistal arthrogryposis (DA) is a group of clinically and genetically heterogeneous disorders characterized by congenital contractures of the distal limb joints without a neuromuscular disease. This case study seeks to report an affected son from an Iranian family with a diagnosis of DA1 with a rare causative genetic defect.Case presentationHerein, we aimed to figure out the underlying genetic of the subject from an Iranian family with DA1. Whole-exome sequencing (WES) of all known DA1 genes was carried out in the proband of the family. WES identified a novel missense mutation, c.456G>C; p.Lys152Asn, within the TPM2 gene, causing a change in one amino acid (Lysine converted to Asparagine). Moreover, this detected variant was confirmed by Sanger sequencing.ConclusionOur data expand the mutational spectra of TPM2 gene associated DA1 which is vital for screening and genetic diagnosis of the disease. Also, this detected mutation has not yet been described in patients with the DA1 phenotype.

Effect of perfusate volume on amikacin concentrations after saphenous intravenous regional limb perfusion in standing, sedated horses.

To determine the influence of perfusate volume on synovial fluid amikacin concentrations in the joints of the hind limb after standing saphenous intravenous regional limb perfusion (IVRLP). Randomized crossover design. Six adult horses. Saphenous IVRLP was performed in 6 standing horses with 1 g of amikacin diluted with 0.9% NaCl to volumes of 10ml, 60 ml, and 120 ml. Samples of synovial fluid from the tarsocrural, metatarsophalangeal, and hind limb distal interphalangeal joints were collected at 15 and 30 min after perfusate administration. Concentrations of 40μg/ml and 160μg/ml were considered therapeutic for susceptible and resistant pathogens, respectively. No difference in synovial fluid amikacin concentrations was detected between volumes in any joint (P= .4). All synovial fluid amikacin concentrations were higher at 30 min compared to 15 min (P= .003). All median synovial fluid amikacin concentrations at 30 min were > 40μg/ml using the 60 ml and 120 ml volumes. Synovial fluid amikacin concentrations >40 μg/ml were only reached in the hind limb distal interphalangeal joint when the 10ml volume was used. All median synovial fluid amikacin concentrations observed were < 160μg/ml. Target concentrations for pathogens that were considered susceptible were consistently reached with perfusate volumes of 60 ml and 120 ml. However, median synovial fluid amikacin concentrations did not reach target levels for resistant pathogens. Perfusate volumes of 60 ml or 120 ml are recommended to treat infections due to susceptible pathogens in the joints of the distal hind limb. These results justify investigation of saphenous IVRLP with different perfusate volumes using higher doses of amikacin.