Distal Portion Research Articles

Dynamic landscape of the intracellular termini of acid-sensing ion channel 1a.

Acid-sensing ion channels (ASICs) are trimeric proton-gated sodium channels. Recent work has shown that these channels play a role in necroptosis following prolonged acidic exposure like occurs in stroke. The C-terminus of ASIC1a is thought to mediate necroptotic cell death through interaction with receptor interacting serine threonine kinase 1 (RIPK1). This interaction is hypothesized to be inhibited at rest via an interaction between the C- and N-termini which blocks the RIPK1 binding site. Here, we use two transition metal ion FRET methods to investigate the conformational dynamics of the termini at neutral and acidic pH. We do not find evidence that the termini are close enough to be bound while the channel is at rest and find that the termini may modestly move closer together during acidification. At rest, the N-terminus adopts a conformation parallel to the membrane about 10 Å away. The distal end of the C-terminus may also spend time close to the membrane at rest. After acidification, the proximal portion of the N-terminus moves marginally closer to the membrane whereas the distal portion of the C-terminus swings away from the membrane. Together these data suggest that a new hypothesis for RIPK1 binding during stroke is needed.

Dynamic landscape of the intracellular termini of acid-sensing ion channel 1a

Acid-sensing ion channels (ASICs) are trimeric proton-gated sodium channels. Recent work has shown that these channels play a role in necroptosis following prolonged acidic exposure like occurs in stroke. The C-terminus of ASIC1a is thought to mediate necroptotic cell death through interaction with receptor interacting serine threonine kinase 1 (RIPK1). This interaction is hypothesized to be inhibited at rest via an interaction between the C- and N-termini which blocks the RIPK1 binding site. Here, we use two transition metal ion FRET methods to investigate the conformational dynamics of the termini at neutral and acidic pH. We do not find evidence that the termini are close enough to be bound while the channel is at rest and find that the termini may modestly move closer together during acidification. At rest, the N-terminus adopts a conformation parallel to the membrane about 10 Å away. The distal end of the C-terminus may also spend time close to the membrane at rest. After acidification, the proximal portion of the N-terminus moves marginally closer to the membrane whereas the distal portion of the C-terminus swings away from the membrane. Together these data suggest that a new hypothesis for RIPK1 binding during stroke is needed.

Stroke in a young adult: looking beyond the diffusion-weighted imaging sequence.

A 37-year-old migrainous woman was referred several hours after a sudden dysarthria lasting less than 1min. Brain MRI undertaken a few hours later showed no acute cerebral infarction on the diffusion-weighted imaging (DWI) sequence. However, an intraluminal thrombus within a distal branch of the middle cerebral artery (MCA) was seen on the T2*-weighted gradient echo images as well as hyperintense vessels related to slow flow beyond the occlusion's site. Control MRI 24h later confirmed the presence of a small infarct affecting the distal portion of the MCA territory but the thrombus was no longer visible. A comprehensive etiologic workup revealed the presence of a patent foramen ovale, as the underlying cause of the patient's stroke. Though the sensitivity of DWI sequence for acute ischemia is high, false negative exist particularly in cases of transient ischemic attack, brainstem or lacunar strokes. A careful brain MRI examination or the use of perfusion weighted imaging sequences are useful to avoid misdiagnosis particularly in young patients.

Extensor Carpi Ulnaris “Turn Around” Ligamentoplasty For Distal Radioulnar Joint Instability

Extensor Carpi Ulnaris “Turn Around” Ligamentoplasty For Distal Radioulnar Joint Instability

Paramedian Supracerebellar Infratentorial Approach for Clipping a Ruptured Aneurysm in the Cerebellomesencephalic Segment of the Left Superior Cerebellar Artery: A Case Report

Superior cerebellar artery (SCA) aneurysms are rare, especially for those arising from the distal portion of the SCA. In this study, we presented a case of a ruptured aneurysm arising from cerebellomesencephalic segment of the SCA. A woman with severe headache and neck stiffness had a ruptured aneurysm arising from cerebellomesencephalic segment of the left SCA. Treated successfully with left-sided paramedian supracerebellar infratentorial (SCIT) approach for clipping the aneurysm with a sitting position, discharged after 14 days without neurological deficit. SCA aneurysms can be managed by endovascular coiling or microsurgical clipping. Although both modalities pose risks of damaging the brainstem perforators, the incidence of the SCIT approach is low since it is exposure from laterally to medially and from distal to proximal along the course of SCA. In our viewpoint, the paramedian SCIT approach is a safe and effective treatment for clipping aneurysms arising from the distal portion of the SCA.

Vascular Tissues Distribution Affects Calcium and Calcium Oxalate Crystals in Fruits of Wild Tomato (Lycopersicon pimpinellifolium (L.) Mill.).

Tomato fruit is an excellent model for evaluating calcium regulation in plants since it expresses symptoms of either calcium deficiency or calcium excess. Aiming to evaluate the structure of the vascular system and its interactions with calcium and calcium oxalate crystals (CaOx), fruits of Lycopersicon pimpinellifolium were studied. Calcium levels were evaluated in basal, median, and distal pericarp portions, which were also analyzed under a light microscope to describe the structure. The L. pimpinellifolium pericarp shows idioblasts with calcium oxalate crystals. Vascular bundles of the basal pericarp show large transverse sections and abundant xylem vessels. The vascular bundles were smaller in the distal pericarp, and the xylem showed fewer and narrower vessels. The terminal bundles often consisted exclusively of phloem. Despite the differences observed in vascular bundle composition, the density of the vascular system was uniform in the pericarp as a consequence of bundle ramifications that occur at distal portions. The calcium concentration and crystal idioblasts decrease towards the apex of the fruit. The reduction in the xylem:phloem ratio seems to determine the low calcium concentration in the distal fruit portion.

MUTYH-associated polyposis: Is it time to change upper gastrointestinal surveillance? A single-center case series and a literature overview

BACKGROUND The presence of Spigelman stage (SS) IV duodenal polyposis is considered the most significant risk factor for duodenal cancer in patients with MUTYH -associated polyposis (MAP). However, advanced SS disease is rarely reported in MAP patients, and no clear recommendations on small bowel (SB) surveillance have been proposed in this patient setting. AIM To research more because that case reports of duodenal cancers in MAP suggest that they may develop in the absence of advanced benign SS disease and often involve the distal portion of the duodenum. METHODS We describe a series of MAP patients followed up at the Regina Elena National Cancer Institute of Rome (Italy). A literature overview on previously reported SB cancers in MAP is also provided. RESULTS We identified two (6%) SB adenocarcinomas with no previous history of duodenal polyposis. Our observations, supported by literature evidence, suggest that the formula for staging duodenal polyposis and predicting risk factors for distal duodenum and jejunal cancer may need to be adjusted to take this into account rather than focusing solely on the presence or absence of SS IV disease. CONCLUSION Our study emphasizes the need for further studies to define appropriate upper gastrointestinal surveillance programs in MAP patients.

Transseptal puncture using electroanatomical mapping: a safe and cost-effective technique

Abstract Background The usual technique of transseptal puncture (TSP) uses fluoroscopy or intracardiac echocardiography. New techniques for oval fossa (OF) identification by electroanatomical mapping (EAM) have been described. However, the technique of direct visualization of the TSP needle added to the OF location by impedance mapping has not been investigated yet. Purpose To evaluate feasibility and safety of the TSP technique guided by the interatrial septum (IAS) impedance mapping and the TSP needle visualization using EAM system. Methods Consecutive patients who underwent ablation using TSP in July and August 2022 in our institute were included. The standard material for the procedure was used in addition to a temporary pacemaker (PM) connection cable. In all cases, the EAM system was CARTO 3 version 7 (Biosense Webster and a bipolar voltage map of right atrium and a impedance map of the IAS were constructed. The OF location was estimated based on the septal region with the lowest impedance and on traditional anatomical landmarks. Using a temporary PM cable connected to the proximal part of the TSP needle stylet, it was possible to visualize its distal portion on the 3D map used to guide the TSP. The entire process was simultaneously monitored under fluoroscopic visualization by an experienced professional. Results A total of 25 patients were included; mean age of 56 +/- 15 years, 16 (64%) were male. The most frequent procedure was atrial fibrillation ablation (86%); left atrium mean size of 40,26 +/- 5,2 mm. 9 patients (36%) were already submetted to a previous procedure using TSP. None of the patients had congenital heart disease. In all cases, the TSP was successfully performed and a correlation between the anatomical references and the lowest impedance region on the map was observed. There were no complications. Conclusion The technique of visualization of the TSP needle using EAM system added to IAS impedance mapping and use of anatomical markers seems to be a safe and cost-effective alternative for performing TSP. This technique could reduce ionizing radiation without need for additional materials.Impedance map and bipolar voltage mapLA (bipolar voltage map) and TSP orifice

Abstract 18628: Focal Pericoronary Adipose Tissue Evaluated by Electron Density Numbers on Contrast Spectral Computed Tomography Was Associated With Coronary Arterial Plaques: A Site-by-Site Analysis

Introduction: Inflammation in pericoronary adipose tissue (PCAT) around the coronary arterial wall causes coronary arterial sclerosis. Many studies evaluated the relationship between total PCAT volume and coronary arterial sclerosis on a patient-by-patient basis. Hypothesis: Inflammation in PCAT may occur focally in coronary arterial system to which coronary arterial plaques localize. Using novel spectral CT, based on electron density number (EDN) as a new parameter, the focal characteristics of PCAT were evaluated. Methods: 17 patients (10 males, mean age 70 years) underwent cardiac spectral CT (7500, Philips, Tokyo, Japan). From contrast data, EDNs of PCAT were determined at a 1) right side site and 2) left anterior side site of a proximal portion of the right coronary arteries (RCA), 3) anterior side site of the left main coronary arteries, 4) left side site of a proximal portion of the left circumflex artery, and left side site of a distal portion of the RCA (five sites each patient). We also evaluated coronary arterial plaques on enhanced CT images at five corresponding sites for which EDNs were determined. Results: For a total of 85 sites among 17 patients using enhanced CT, 31 sites had no plaques (group 1), 14 sites had only non-calcified plaques (group 2), 20 sites had only calcified plaques (group 3), 16 sites had mixed plaques (group 4), and four sites had stent implantations (group 5). The mean of EDNS (%EDW) for 81 sites, excluding four sites with a stent implantation, were 93.7, 93.9, 94.0, and 94.3 in groups 1-4, respectively (P=NS). For a total of 81 sites, excluding four implantation sites, we evaluated the relationship between age and EDNs in groups 1-4. No correlations were observed in group 1 (R= 0.05), 3 (R= 0.09), and 4 (R= 0,15), however negative correlation was observed in group 2 (R= -0.42) between age and EDNs. No significant differences in EDNs were noted between males and females (P=NS). Conclusions: This is the first study in which focal PCAT was evaluated by EDNs and the relationship to coronary arterial plaques determined by site-by-site analysis. This new CT parameter may evaluate the status of PCAT and be a predictor of the future occurrence of coronary arterial plaques, which are related to PCAT inflammation.

Abstract 18549: Focal Pericoronary Adipose Tissue Evaluated by Atomic Numbers on Contrast Spectral Computed Tomography Was Associated With Coronary Arterial Plaques: A Site-by-Site Analysis

Introduction: Inflammation in pericoronary adipose tissue (PCAT) around the coronary arterial wall causes coronary arterial sclerosis. Many studies evaluated the relationship between total PCAT volume and coronary arterial sclerosis on a patient-by-patient basis. Hypothesis: Inflammation in PCAT may occur focally in coronary arterial system to which coronary arterial plaques localize. Using novel spectral CT, based on atomic number as a new parameter, the focal characteristics of PCAT were evaluated. Methods: 17 patients (10 males, mean age 70 years) underwent cardiac spectral CT (7500, Philips, Tokyo, Japan). From contrast data, atomic numbers of PCAT were determined at a 1) right side site and 2) left anterior side site of a proximal portion of the right coronary arteries (RCA), 3) anterior side site of the left main coronary arteries, 4) left side site of a proximal portion of the left circumflex artery, and left side site of a distal portion of the RCA (five sites each patient). We also evaluated coronary arterial plaques on enhanced CT images at five corresponding sites for which atomic numbers were determined. Results: For a total of 85 sites among 17 patients using enhanced CT, 31 sites had no plaques (group 1), 14 sites had only non-calcified plaques (group 2), 20 sites had only calcified plaques (group 3), 16 sites had mixed plaques (group 4), and four sites had stent implantations (group 5). The mean of atomic numbers for 81 sites, excluding four sites with a stent implantation, were 6.4, 6.8, 6.4, and 6.1 in groups 1-4, respectively (P=NS). For a total of 81 sites, excluding four implantation sites, we evaluated relationship between age and atomic numbers in groups 1-4. Positive correlations were observed in group 1 (R= 0.25) and 3 (R= 0.39), however negative correlation was observed in group 2 (R= -0.37) and 4 (R= -0.40) between age and atomic numbers. No significant differences in atomic numbers were noted between males and females. Conclusions: This is the first study in which focal PCAT was evaluated by atomic numbers and the relationship to coronary arterial plaques determined by site-by-site analysis. This new CT parameter may evaluate the status of PCAT and be a predictor of future occurrence of coronary arterial plaques, which are related to PCAT inflammation.

Abstract 18610: Focal Pericoronary Adipose Tissue Evaluated by Electron Density Numbers on Non-Contrast Spectral Computed Tomography Was Associated With Coronary Arterial Plaques: A Site-by-Site Analysis

Introduction: Inflammation in pericoronary adipose tissue (PCAT) around the coronary arterial wall causes coronary arterial sclerosis. Many studies evaluated the relationship between total PCAT volume and coronary arterial sclerosis on a patient-by-patient basis. Hypothesis: Inflammation in PCAT may occur focally in coronary arterial system to which coronary arterial plaques localize. Using novel spectral CT, based on electron density number (EDN) as a new parameter, the focal characteristics of PCAT were evaluated. Methods: 17 patients (10 males, mean age 70 years) underwent cardiac spectral CT (7500, Philips, Tokyo, Japan). From non-contrast data, EDNs of PCAT were determined at a 1) right side site and 2) left anterior side site of a proximal portion of right coronary arteries (RCA), 3) anterior side site of the left main coronary arteries, 4) left side site of a proximal portion of the left circumflex artery, and left side site of a distal portion of the RCA (five sites each patient). We also evaluated coronary arterial plaques on enhanced CT images at five corresponding sites for which EDNs were determined. Results: For a total of 85 sites among 17 patients using enhanced CT, 31 sites had no plaques (group 1), 14 sites had only non-calcified plaques (group 2), 20 sites had only calcified plaques (group 3), 16 sites had mixed plaques (group 4), and four sites had stent implantations (group 5). The mean of EDNS (%EDW) for 81 sites, excluding four sites with a stent implantation, were 93.5, 93.3, 93.2, and 93.8 in groups 1-4, respectively (P=NS). For a total of 81 sites, excluding four implantation sites, we evaluated the relationship between age and EDNs in groups 1-4. Positive correlations were observed in group 1 (R= 0.40), and 3 (R= 0.40), however negative correlation was observed in group 2 (R= -0.22) and 3 (R= -0.22) between age and EDNs. No significant differences in EDNs were noted between males and females (P=NS). Conclusions: This is the first study in which focal PCAT was evaluated by EDNs and the relationship to coronary arterial plaques determined by site-by-site analysis. This new CT parameter may evaluate the status of PCAT and be a predictor of the future occurrence of coronary arterial plaques, which are related to PCAT inflammation even on non-contrast CT alone.

Titanium Versus Carbon-Fiber Reinforced Intramedullary Nailing for Humeral Bone Tumors.

Multiple techniques have been described to treat humeral diaphyseal bone tumors requiring curettage or excision. Recent studies have suggested that carbon-fiber-reinforced polyetheretherketone (CFR-PEEK) intramedullary nails (IMNs) may be preferable to titanium IMNs for patients with musculoskeletal tumors due to CFR-PEEK's high tensile strength, radiolucency, a modulus of elasticity closer to native bone, and improved postoperative surveillance/radiation dosing. In this study, we describe the rate of fixation failure for both CFR-PEEK and titanium humeral IMNs when used for humeral diaphyseal bone tumors requiring curettage or excision. This was a single-institution retrospective cohort study including 81 patients (27 CFR-PEEK and 54 titanium) treated for a humeral diaphyseal bone tumor using an IMN +/- methylmethacrylate between January 2017 and December 2022. Primary outcome was revision surgery due to soft tissue complications, non-unions, structural complications such as periprosthetic fracture or IMN breakage, periprosthetic infection, tumor progression, and implant failure due to rejection or fatigue. No failures were observed in either patients treated with titanium nails or patients treated with CFR-PEEK not requiring curettage. Fixation failure due to implant failure was observed in two cases - at 214 days and 469 days after surgery - where CFR-PEEK IMN was used for stabilization after a wide segmental resection for oncologic control with a cement spacer reconstruction. In both cases, the resection was larger than 6 cm, the remaining distal humerus was less than 5 cm, and failures occurred at the interface of the residual bone and spacer. Both patients were revised using a titanium distal posterolateral humeral plate fixed with screws and cables without any subsequent complications. One additional CFR-PEEK IMN required revision surgery after 744 days due to progression of the tumor and subsequent non-union. One revision surgery was observed after 63 days for the titanium IMN due to non-union and tumor progression. Humeral diaphyseal bone tumors requiring large segmental resection with small residual bone and a large cement spacer may fail via tension due to bending forces at the distal portion. In this clinical scenario, the use of larger diameter CFR-PEEK IMNs may be indicated when these are available. In the interim, use of intercalary allografts instead of cement spacers, additional fixation with a titanium plate distally, or the use of a titanium nail when using a cement spacer may be considered.

Abstract 100: Endovascular treatment of a traumatic near‐miss vessel injury

Introduction Traumatic injuries are a common cause of death, representing nearly 8% of all deaths worldwide(1). Vascular injury can occur in about 3% to 20% of the patients that suffer from a blunt or penetrating craniocervical injury (2). The most commonly injured arteries from penetrating trauma include CCA, ICA, and ECA (73%,22%, and 5% respectively)(3). Embolization is now a well‐established endovascular technique to treat traumatic hemorrhagic injuries(4). We present a case of a patient with a near‐miss injury treated endovascularly. Methods We present the case of a 29‐year‐old male who was found unconscious with a knife embedded in his left face. On arrival at the hospital, the patient was hemodynamically stable with no ongoing hemorrhage or respiratory distress. CTA did not reveal any vascular injury; however, due to the knife's location, the neurointerventional radiology team was consulted and performed an embolization of the proximal third of the internal maxillary artery. The patient was later taken to the operating room for the removal of the knife. Results The non‐serrated end of the knife had resulted in impingement of the distal left ECA just proximal to the bifurcation of the superficial temporal artery and internal maxillary artery and resulting in approximately 80% narrowing of the vessel. Given the extent of impingement of the foreign object on the distal portion of the left ECA, after discussing with the otolaryngology team, a decision was made to proceed with coil embolization of the vessel due to concerns for vessel injury which can result in life‐threatening hemorrhage or pseudoaneurysm during removal of the foreign object in the OR. A total of 4 HydroFrame coils were deployed from the proximal one‐third of the internal maxillary artery into the ECA covering the superficial temporal artery to the origin of the occipital artery. 2 MicroPlex 5mm x 22cm Cosmos 10 bare platinum coils were placed intact to the left ECA extending proximally just distal to the occipital artery. Final AP projection of the left ECA post coil embolization was performed showing complete occlusion of the vessel across the area of impingement at the distal ECA proper. Retrograde filling of the internal maxillary artery was noted. The left middle meningeal artery is occluded and no longer visualized as its origin is being covered by coils. Patient underwent foreign object removal by ENT and had a good functional outcome. Conclusion Endovascular intervention prior to foreign object removal can improve outcomes and decrease the risk of severe vascular injury.

Separation of the glanular part of the urethral plate, mobilization of the distal part of the neourethra, and creation of the glanular groove: a new modification of second-stage Thiersch-Duplay urethroplasty in proximal hypospadias repair.

To evaluate the effect of separation of the glanular part of the urethral plate from the underlying glans penis with creation of a glanular groove for free accommodation of the neourethra as a new modification of Thiersch-Duplay urethroplasty in proximal hypospadias repair. Between January 2016 and January 2022, 35 patients with proximal hypospadias underwent a modified Thiersch-Duplay two-stage procedure. The glanular portion of the urethral plate was either separated from the underlying glanular tissue or discarded if found scared with mobilization of the distal portion of the neourethra to reach the tip of the glans penis. In all patients, a few millimeter of glanular tissue is excised to create a glanular groove in which the neourethra is embedded freely. 35 patients were involved in this study. The patient's age at the time of operation ranged from 18months to 10years (median 3.7years). The mean follow-up period was 15.7months (ranging from 12 to 18months). Two patients developed urethrocutaneous fistula; while, none of the patients had meatal stenosis, urethral stricture, or meatal retraction. All patients have a slit-like meatus at the tip of the penis and a good cosmetic conical shape glans appearance. We believe that in Thiersch-Duplay urethroplasty, separation of the urethral plat from the underlying glanular tissue and creation of good glandular groove to accommodate the neourethra is associated with adequate glanular closure and minimization of post-operative meatal stenosis, glanular dehiscence, and meatal retraction.

Submucosal tunneling endoscopic full-thickness resection for management of a rare case of esophageal GI stromal tumor

Video 1The mass was identified at the upper- to mid-esophagus, 25 cm from the central incisors. No varices were seen on further examination of the esophagus. A 4-mm injector force needle was used to create a large submucosal injection using BlueBoost lifting agent proximal to the mass. A longitudinal mucosal incision was then made using the hybrid T-type electrocautery knife, 20 cm from the central incisors.The cutting current was the preset Endocut Q mode, and the coagulation setting was spray coag mode, effect 2 and 40 W.Next, tunnel creation by submucosal dissection was performed with a focus on keeping the submucosal space as clean as possible. Carbon dioxide was used for insufflation to prevent pneumoperitoneum.A smooth-surfaced oval mass was identified originating from the muscularis propria layer. Dissection was extended 2 cm distally beyond the mass. Next, resection of the mass was performed. First, the mucosal surface of the mass was dissected. Dissection began at the distal portion, proceeded to the left and right lateral borders, and then continued toward the proximal portion. The mass was dissected away from the muscularis propria.We focused on freeing the mass, ensuring this esophageal mass was intact throughout dissection. The attached bands of muscularis propria at the distal portion were carefully resected completely.Water irrigation was used at this time to ensure better visualization for resection. The remaining attached bands of muscularis propria were resected, ensuring complete en bloc resection. Afterward, the mass was suctioned into the cap and carefully retrieved as shown, and then sent to pathology for processing.The entire defect bed was inspected post-resection, and no perforation or bleeding was identified.The mucosal defect was completely closed with through-the-scope hemostatic clips in a longitudinal fashion beginning with approximation of the defect at the distal portion.

Predicting the effects of spatiotemporal modifications of muscle activation on the tentacle extension in squid.

Squid use eight arms and two slender tentacles to capture prey. The muscular stalks of the tentacles are elongated approximately 80% in 20-40ms towards the prey, which is adhered to the terminal clubs by arrays of suckers. Using a previously developed forward dynamics model of the extension of the tentacles of the squid Doryteuthis pealeii (formerly Loligo pealeii), we predict how spatial muscle-activation patterns result in a distribution of muscular power, muscle work, and kinetic and elastic energy along the tentacle. The simulated peak extension speed of the tentacles is remarkably insensitive to delays of activation along the stalk, as well as to random variations in the activation onset. A delay along the tentacle of 50% of the extension time has only a small effect on the peak extension velocity of the tentacle compared with a zero-delay pattern. A slight delay of the distal portion relative to the proximal has a small positive effect on peak extension velocity, whereas negative delays (delay reversed along stalk) always reduce extension performance. In addition, tentacular extension is relatively insensitive to superimposed random variations in the prescribed delays along the stalk. This holds in particular for small positive delays that are similar to delays predicted from measured axonal diameters of motor neurons. This robustness against variation in the activation distribution reduces the accuracy requirements of the neuronal control and is likely due to the non-linear mechanical properties of the muscular tissue in the tentacle.

Geochronology of reworked ash and its implications for accommodation space variations in distal foreland basins, McMurray Formation, Alberta, Canada

A bentonite bed consisting of reworked volcanic ash from the Barremian to Aptian lower McMurray Formation is dated using chemical abrasion thermal ionization mass spectrometry (CA-TIMS) on zircon. The bentonite bed is from a cored interval in the McKay Paleovalley in the northern Athabasca Oil Sands Region of Alberta, Canada. Deposition of the lower McMurray Formation took place in the distal portion of the Western Canada Sedimentary Basin early in the Cretaceous-to-Paleocene phase of widespread contractional deformation in the Canadian Cordillera. A 30 g sample of volcanic ash yielded >10,000 very small (<50 µm) zircon grains with the vast majority (~99.7%) being highly abraded and clearly detrital. Twenty-six sharply faceted grains were sufficiently large to be mounted for laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) analysis, which yielded seven Lower Cretaceous dates. These Lower Cretaceous grains were further analyzed using CA-TIMS. The five youngest CA-TIMS dates agree with a weighted mean of 121.51 ± 0.11 Ma which is conservatively interpreted as a maximum depositional age (MDA). The good agreement between the five zircon dates indicates the MDA is probably the depositional age. This study demonstrates that with careful analysis of zircon populations, high-confidence MDAs can be derived even from reworked ash beds that are dominated overwhelmingly by detrital zircon. The date from this study overlaps a previously published MDA of 121.39 ± 0.27 Ma for the top of the lower McMurray Formation in Firebag Tributary in the northeastern Athabasca Oil Sands Area. The overlapping dates establish a widespread chronostratigraphic surface within the northern Athabasca Oil Sands Area. Both ages are from ash beds preserved in coal seams, suggesting that the coal-bearing interval is a regional marker bed and that the ash beds may form an intraformational datum. Further, the occurrence of the ash beds in the McMurray Formation in close proximity to regional flooding surfaces suggests that tectonic activity in the emerging Canadian Cordillera influenced accommodation space variations in the distal portions of the adjacent foreland basin.

How Does Lateral Column Lengthening Correct the Flatfoot? A Cadaveric Study

Category: Hindfoot; Basic Sciences/Biologics Introduction/Purpose: Since its description by Evan for correction of overcorrected clubfoot cases, lateral column lengthening ( LCL) has been widely used for correction of pes planovalgus deformity of any etiolog. The main indication is correction of forefoot abduction manifested radiologically as talonavicular uncoverage. It was reported by many authors that LCL improved forefoot abduction and talonavicular uncoverage, but it was also noticed that LCL corrects the flattening of medial longitudinal arch. The mechanism by which LCL corrects the medial longitudinal arch is still not clearly understood. It was also reported that LCL is associated with forefoot supination, but the exact mechanism of supination is not understood. This study aimed to try to understand the mechanism by which LCL changes the shape of the foot. Methods: LCL osteotomy using Hintermann technique was performed in ten fresh frozen below knee cadaveric specimens. After completion of the osteotomy, the talus and leg were removed to monitor how the foot moves under the talus with opening of the osteotomy to change the shape of the foot. The amounts of osteotomy displacement medially, laterally and planetary were observed and measured. After that, the whole plantar skin was removed and plantar ligaments were dissected to study the influence of plantar ligaments on the plane of motion of the osteotomy and the effect of the osteotomy on plantar ligaments. Results: With opening of the osteotomy, the distal portion did not move in pure adduction. Instead, it moved medial and plantar, working as a dorsolateral opening wedge . So, the distal portion was adducted and plantarflexed correcting the forefoot abduction and the flat arch. Because the osteotomy opens dorsally and laterally only, the lateral part of the distal portion was plantar flexed more than the medial part, and this is the cause of forefoot supination. After dissection of plantar ligaments, it was found that the long and short plantar ligaments prevent the osteotomy from opening inferiorly . It was possible to move the distal portion in pure adduction only after cutting the long and short plantar ligaments. Plantar fascia was relaxed after opening of the osteotomy. Conclusion: This mayexplain how the LCL osteotomy corrects the flat medial longitudinal arch and how it causes supination and lateral side overload. Based on this study, Cotton osteotomy should be added to LCL to correct the supination. Also, plantar fascia tightening can not be the cause of medial longitudinal arch correction as it actually becomes more lax after opening of the osteotomy.

Association of Smoking, Diabetes, and Dialysis with the Presence of Popliteal Lesions in Femoropopliteal Artery Disease.

Although recent advances in endovascular devices have markedly improved clinical outcomes of femoropopliteal endovascular therapy, lesions located in the popliteal artery are still a major challenge. This study aimed to determine the association of cardiovascular risk factors, including smoking, diabetes mellitus, and dialysis-dependent renal failure, with the location of atherosclerotic lesions in femoropopliteal artery disease. We used a multicenter prospective study database registering patients with symptomatic femoropopliteal artery disease undergoing drug-coated balloon treatment. The analysis included 1912 patients with de novo femoropopliteal lesions. The association of clinical characteristics with popliteal lesions was investigated using the logistic regression model. In addition, the femoropopliteal artery was divided into six segments (the proximal, middle, and distal portions of the superficial femoral artery and P1, P2, and P3 segments of the popliteal artery), and the association of clinical characteristics with the presence of atherosclerotic lesions in the respective arterial segments was investigated. Smoking and dialysis-dependent renal failure showed a statistically significant inverse and positive association with the presence of popliteal lesions, respectively (adjusted odds ratio, 0.66 [95% confidence interval, 0.51-0.85] and 2.01 [1.62-2.49]; P=0.001 and P＜0.001), whereas diabetes mellitus did not (P=0.17). The subsequent per-segment analysis presented similar results. Smoking was inversely associated with popliteal lesions, whereas renal failure on dialysis was positively associated in patients with symptomatic femoropopliteal artery disease who underwent drug-coated balloon treatment. Diabetes mellitus was not significantly associated.

The efficacy of hyaluronidase on flap survival: an animal model.

It has been hypothesized that hyaluronidase may allow fluid to enter and exit the basal area of the flap more readily and thus allow waste metabolites from the distal portion of the flap to drain towards areas where the blood supply may be healthier. We aimed to test this hypothesis by seeing whether hyaluronidase enhances the survival of a flap created in an animal model. The experiment utilized 14 male Wistar rats to test the effect of administering hyaluronidase on flap survival. The study utilized the same "flap survival method" technique reported in numerous previous studies. The area of necrosis in the animals of the intervention group was lower than in the control animals, and this result reached statistical significance. Hyaluronidase may preserve tissue flap vitality, starting at the bottom end of the dosage range. Future research should establish the minimal concentration needed to obtain benefits. The optimal mode of administration, whether by injection or topical application, is also a topic for future studies.