Grayson Ligament:A Revised Description of its Anatomy and Function

PURPOSE: Grayson ligament has been described as a common pathway for digital contracture in Dupuytren disease. Its anatomical descriptions in the literature are, however, inconsistent. METHODS: We have performed a microsurgical dissection study in 20 fresh-frozen and thawed digits to revisit the anatomy of Grayson ligaments. We also performed dissections in Thiel-preserved hands to be able to study the changes in tension of the ligaments during flexion and extension of the finger. RESULTS: We found the ligaments originally described by Grayson to be the best developed part of a trabecular network of fibers, originating in continuity with the outer adventitial layer of the flexor tendon sheath and running toward their insertions into the skin in multiple planes, all volar to the neurovascular bundle. The most dorsal fibers, which cover the neurovascular bundles, form a chevron shape with its midline apex pointing distally in an extended finger. During flexion, the fibers become more transversely oriented. CONCLUSIONS: We found Grayson ligament comprises a trabecular network of fibers, instead of a ligament, with a dynamic fiber orientation on the volar side of the finger. The main function of this network of fibers seems to be the stabilization of the skin and fat pad in digit extension while the relaxation in flexion allows the skin and volar fat pad to adapt optimally to the form of the object that is held. CLINICAL RELEVANCE: The new insights in the anatomy of Grayson trabecular network of fibers may be of importance in the understanding of the pathological anatomy of Dupuytren disease

Modelling Mixed Microbial Culture Polyhydroxyalkanoate Accumulation Bioprocess towards Novel Methods for Polymer Production Using Dilute Volatile Fatty Acid Rich Feedstocks

Volatile fatty acid (VFA) rich streams from fermentation of organic residuals and wastewater are suitable feedstocks for mixed microbial culture (MMC) Polyhydroxyalkanoate (PHA) production. However, many such streams have low total VFA concentration (1–10 gCOD/L). PHA accumulation requires a flow-through bioprocess if the VFAs are not concentrated. A flow through bioprocess must balance goals of productivity (highest possible influent flow rates) with goals of substrate utilization efficiency (lowest possible effluent VFA concentration). Towards these goals, dynamics of upshift and downshift respiration kinetics for laboratory and pilot scale MMCs were evaluated. Monod kinetics described a hysteresis between the upshift and downshift responses. Substrate concentrations necessary to stimulate a given substrate uptake rate were significantly higher than the concentrations necessary to sustain the attained substrate uptake rate. A benefit of this hysteresis was explored in Monte Carlo based PHA accumulation bioprocess numerical simulations. Simulations illustrated for a potential to establish continuous flow-through PHA production bioprocesses even at a low (1 gCOD/L) influent total VFA concentration. Process biomass recirculation into an engineered higher substrate concentration mixing zone, due to the constant influent substrate flow, enabled to drive the process to maximal possible PHA production rates without sacrificing substrate utilization efficiency

The anatomy and function of Cleland's ligaments

The cutaneous ligaments of the digits have been recognized by anatomists for several centuries, but the best known description is that of John Cleland. Subsequent varying descriptions of their morphology have resulted in the surgical community having an imprecise view of their structure and dynamic function. We micro-dissected 24 fresh frozen fingers to analyze the individual components of Cleland's ligamentous system. Arising from the proximal interphalangeal (PIP) joint, proximal, and sometimes middle phalanx, we found strong ligaments that ran proximally (PIP-P) and distally (PIP-D). On each side of each finger there was a PIP-P ligament present, which passed obliquely from the lateral side of the proximal and sometimes middle phalanx towards its insertion into the skin at the level of the proximal phalanx. The distal (PIP-D) ligaments were found to pass obliquely distally on the radial and ulnar aspects of the digit towards cutaneous insertions around the middle phalanx. A similar arrangement exists more distally with fibres originating from the DIP joint and middle phalanx (the DIP-P pass obliquely proximally, and the DIP-D, distally). Each individual PIP ligament consisted of three different layers originating from fibres overlying the flexor tendon sheath, periosteum or joint capsule, and extensor expansion. Ligaments arising at the DIP joint had two layers equivalent to the anterior two layers of the proximal ligaments. Cleland's ligaments act as skin anchors maintaining the skin in a fixed relationship to the underlying skeleton during motion and functional tasks. They also prevent the skin from 'bagging', protect the neurovascular bundle, and create a gliding path for the lateral slips of the extensor tendon

Ethnic differences in prevalence of Dupuytren disease can partly be explained by known genetic risk variants

Dupuytren disease (DD), a fibroproliferative disorder of the palmar fascia that causes flexion contractures in the fingers, is prevalent in people of North-Western European descent and less so in other ethnicities. DD is a complex disorder, influenced by genetic risk variants. We aimed to study if the marked differences in prevalences in DD between ethnic (sub)groups could be explained by differences in allele frequencies of the 26 known genetic risk variants of DD. Therefore, genetic risk scores (GRS) composed of the 26 DD risk variants were calculated for the 26 populations from the 1000 Genomes database and correlated to observed DD prevalences from literature. For comparison, GRSs were generated for 10,000 sets of 26 random SNPs and also correlated to the observed DD prevalences to determine the significance of the observed correlation. To determine whether differences in allele frequencies between ethnicities were caused by natural selection, fixation indices (Fst) were calculated from the 26 SNPs and from the sets of 26 random SNPs for comparison. Observed prevalences could be determined from literature for 10 populations. Their correlation with the GRS composed of DD SNPs proved to be 0.60 (p = 0.0003). The Fsts between British and other populations were low for European, ad mixed American, and South-Asian populations, and moderate for East-Asians. African populations were significantly different from expected values determined from the random sets. In conclusion, the 26 known genetic risk variants associated with DD explain for a substantial part (R-2 = 0.36) the differing DD prevalences observed between ethnicities

Producing holograms of reacting sprays in liquid propellant rocket engines Final report

Holograms and laser-illuminated photography of reacting sprays in liquid propellant rocket engine

Limited progression of subclinical Dupuytren's disease:results from a prospective cohort study

AIMS: With novel promising therapies potentially limiting progression of Dupuytren's disease (DD), better patient stratification is needed. We aimed to quantify DD development and progression after seven years in a population-based cohort, and to identify factors predictive of disease development or progression. METHODS: All surviving participants from our previous prevalence study were invited to participate in the current prospective cohort study. Participants were examined for presence of DD and Iselin's classification was applied. They were asked to complete comprehensive questionnaires. Disease progression was defined as advancement to a further Iselin stage or surgery. Potential predictive factors were assessed using multivariable regression analyses. Of 763 participants in our original study, 398 were available for further investigation seven years later. RESULTS: We identified 143/398 (35.9%) participants with DD, of whom 56 (39.2%) were newly diagnosed. Overall, 20/93 (21.5%) previously affected participants had disease progression, while 6/93 (6.5%) patients showed disease regression. Disease progression occurred more often in patients who initially had advanced disease. Multivariable regression analyses revealed that both ectopic lesions and a positive family history of DD are independent predictors of disease progression. Previous hand injury predicts development of DD. CONCLUSION: Disease progression occurred in 21.5% of DD patients in our study. The higher the initial disease stage, the greater the proportion of participants who had disease progression at follow-up. Both ectopic lesions and a positive family history of DD predict disease progression. These patient-specific factors may be used to identify patients who might benefit from treatment that prevents progression. Cite this article: Bone Joint J 2021;103-B(4):704-710

Patient-perceived hand function measured can predict treatment for Dupuytren's disease

BACKGROUND: Web based patient-reported outcome measures (PROMs) could aid surgeons to remotely assess the need for examination and subsequent treatment of Dupuytren's disease (DD) patients. We studied whether the Unité Rhumatologique des affections de la Main (URAM) and the Michigan Hand Questionnaire (MHQ) could predict DD treatment.METHODS: In this prospective cohort study, we compared MHQ and URAM scores of treated patients with untreated patients. For the treatment group, we selected a score closest to one year before treatment. For controls we randomly selected a score. Additionally, we tested the predictive value of a one-year change score between 15 months and 6 weeks before treatment. The primary outcome measure was DD treatment.The predictive value was determined using the Area Under the Curve (AUC). An AUC &gt;0.70 was considered as good predictive ability, 0.70-0.50 as poor predictive ability and &lt;0.50 as no predictive ability.RESULTS: We included 141 patients for the MHQ analysis and 145 patients for the URAM analysis. The AUC of the MHQ and URAM scores measured one year before treatment were 0.80 (95% CI 0.71-0.88) and 0.75 (95% CI 0.68-0.82), respectively. The one-year change score resulted in an AUC of &lt;0.60 for both questionnaires.CONCLUSIONS: Our results show that both the MHQ and URAM score measured around one year before treatment can predict treatment for DD. If future studies show that telemonitoring of DD patients with PROMs is also cost-effective, web-based PROMs could optimise patient care and treatment effectiveness of DD.</p

Three-Dimensional Stereophotogrammetry Assessment of Facial Asymmetry in Facial Palsy

Three-dimensional stereophotogrammetry is not much used in assessing facial palsy and a comprehensive understanding of sources of variation in these measurements is lacking. The present study assessed intra- and interobserver reliability of a novel three-dimensional stereophotogrammetry measurement of facial asymmetry and examined sources of variation in these outcomes. Three photographs (rest, closed mouth smile, and maximum smile) were made of 60 participants, 30 facial palsy patients and 30 control subjects. All images were analyzed twice by 2 observers independently, to determine intra- and interobserver reliability. Variance component analysis was performed to investigate sources of variation in the outcomes. Intraobserver reliability was good with intraclass correlation coefficients ranging from 0.715 to 0.999. Interobserver reliability ranged from 0.442 to 0.929. Reliability of the smile image measurements was not clearly different from the rest images. Variation in measurement results was largely due to the status of a participant, facial palsy versus control. When splitting the sample, the facial expression was a major source of variation. Acceptable reliability of the proposed 3D facial asymmetry measurement was found, in facial palsy patients and control subjects. Interobserver reliability was marked less compared to intraobserver reliability. For follow-up data only one observer should assess 3D stereophotogrammetry measurements

Further evidence of the involvement of the Wnt signaling pathway in Dupuytren's disease

Genetic background plays an important role in the development of Dupuytren's disease. A genome-wide association study (GWAS) showed that nine loci are associated with the disease, six of which contain genes that are involved in Wnt signaling (WNT2, WNT4, WNT7B, RSPO2, SFRP4, SULF1). To obtain insight in the role of these genes, we performed expression studies on affected and unaffected patient's tissues. Surgically obtained nodules and cords from eight Dupuytren's patients were compared to patient-matched control tissue (unaffected transverse palmar fascia). The Wnt-related genes found in the GWAS, the classical Wnt-downstream protein beta-catenin, as well as (myo) fibroblast markers were analyzed using real-time qPCR and immunohistochemical stainings for mRNA levels and protein levels, respectively. The collagen-coding genes COL1A1 and COL3A1 were highly upregulated on mRNA level, both in cords and nodules. Three Wnt-related genes were found to be differently regulated compared to control tissue: WNT2 was downregulated in nodules, WNT7B was upregulated in nodules, and SFRP4 was upregulated in nodules and cords. Immunohistochemistry revealed significantly less staining of Wnt2 in cords, but significantly more staining for Wnt7b in nodules. There was significantly more staining of alpha-SMA in nodules and cord and beta-catenin in nodules than in control tissue. We found differences in expression, both at mRNA and protein level, in several Wnt-related genes found earlier to be associated with Dupuytren's disease. Of these, Wnt7b was upregulated and found in close association with both alpha-SMA and beta-catenin expressing cells, making it a candidate pro-fibrotic mediator in Dupuytren's disease