Surgical anatomy of the cerebellar tonsils: A cadaveric study.

BACKGROUND: Knowledge of the normal anatomy of the cerebellar tonsils is a prerequisite in various surgeries of the posterior cranial fossa Clinical conditions, as the Chiari I malformations (CIM) alter the normal position of the cerebellar tonsils. OBJECTIVE: Therefore, we aim to better elucidate the surgical anatomy of and around the cerebellar tonsils in regard to the CIM. METHODS: Fifty formalin-fixed adult cadavers injected with colored latex through vertebral arteries underwent craniotomy and durotomy to expose the cerebellar tonsils and related structures. The tonsils and their surrounding anatomy were then studied. RESULTS: Forty cerebellar tonsils were at or above the foramen magnum. Five specimens presented with CIM with the tonsils below (3-5 mm) the FM with a mean tonsillar decent of 7.9 ± 2.3 mm. Of the cadavers without CIM, in forty-two cases, the thickness of the dura mater was within ±3SD ranges. In three cases, the dura mater was thinner at the CVJ and one case; the dura adhered tightly to the inner aspect of the occipital squama. In five CIM cadavers, the dura mater was markedly thicker at the CVJ. The PICA caudal loop was 5.9 ± 1.6 mm long. In CIM cases, the PICA loop was longer, nearer the dura, 1 mm below the superior border of the C1 posterior arch. The distances from the PICA loop were markedly reduced by 3 mm from the spinal accessory nerve and 2 mm from the first spinal nerve. The DN was significantly closer to the tonsillar peduncle in CIM cases. CONCLUSION: These data are important for better understanding the intrinsic and extrinsic anatomy of the cerebellar tonsils in patients with and without CIM. Importantly, tonsillectomy/tonsillar coagulation must consider the close relationship of the dentate nucleus to the base of the cerebellar tonsil to avoid iatrogenic injury.

Investigating the Glucagon-like Peptide-1 and Its Receptor in Human Brain: Distribution of Expression, Functional Implications, Age-related Changes and Species Specific Characteristics.

Introduction: Emerging evidence has shown that the glucagon-like peptide-1 (GLP-1) agonist can be used to treat Alzheimer disease; however, knowledge of its neural targets is limited. To understand the neural substrates of GLP-1, we have done whole brain mapping for GLP-1 and its receptor (GLP-1R), in 30 human brains. Methods: GLP-1 expression was studied by immuno-histochemistry and confirmed by the western blot method. The GLP-1R gene expression was studied by reverse transcription polymerase chain reaction. Results: GLP-1 expression was observed in most of the cortical areas (maximum in frontal, prefrontal and parietal cortex), diencephalon, and brainstem, but not in the cerebellum. Protein expression studies validated these results. The highest expression of GLP-1R was found in the frontal cortex. The orbitofrontal cortex and cerebellum had negligible expression. Hippocampus demonstrated a significant presence of GLP-1R but patchy immunoreactivity to GLP-1. GLP-1R presence in most of the human cortical regions and absence in the cerebellum is the major deviation from the animal brain. Sites that might be of interest in Alzheimer have been identified. GLP-1 demonstrated an age-related decline in most of the areas after the fifth decade. At 60 years, GLP-1 was not found in any of the cortical areas except in the prefrontal cortex; however, it was present in the sub-cortical areas. Conclusion: Age-related profiling of GLP-1 in various brain areas has been analyzed, which can have an important bearing on understanding Alzheimer disease. This study provides a detailed description of GLP-1 and an brain mapping for the first time and may lead to novel treatment options targeting the GLP-1 receptors. Highlights: Glucagon like peptide-1 (GLP-1) agonist can be used for treating Alzheime'rs disease.GLP-1 gene expression was seen in cortical areas, diencephalon and brainstem, but not in cerebellum.Hippocampus demonstrated significant presence of GLP-1R but patchy immunoreactivity to GLP-1.GLP-1 demonstrated age related decline in most of the areas after fifth decade.A detailed description of GLP-1 and amp; GLP-1R locations was given which may lead to novel treatment options. Plain Language Summary: Emerging evidence has shown that the glucagon like peptide-1 (GLP1-1) agonist can be used for treating Alzheimer's disease but knowledge of its neural targets is limited. To understand the neural substrates of GLP-1, we have done whole brain mapping for GLP-1 and its receptor (GLP-1R), in 30 human brains. GLP-1 expression was studied by immuno-histochemistry and confirmed by western blot method. GLP-1R gene expression was studied by RT-PCR. GLP-1 expression was seen in most of the cortical areas (maximum in frontal, prefrontal & amp; parietal cortex), diencephalon and brainstem, but not in cerebellum. Protein expression studies validated these results. Highest expression of GLP-1R was found in the frontal cortex. The orbito-frontal cortex and cerebellum had negligible expression. Hippocampus demonstrated significant presence of GLP-1R but patchy immunoreactivity to GLP-1. GLP-1R presence in most of the human cortical regions and absence in cerebellum is the major deviation from the animal brain. Sites which might be of interest in Alzheimer's have been identified. GLP-1 demonstrated age related decline in most of the areas after 5 th decade. At 60 years GLP-1 was not found in any of the cortical areas except in the prefrontal cortex but it was present in the sub-cortical areas. Age related profiling of GLP-1 in various brain areas has been analysed, which can have important bearing on understanding the Alzheimer's. This study provides detailed description of GLP-1 and ations by complete human brain mapping for the first time and may lead to novel treatment options targeting the GLP-1 receptors.

Reelin Signaling Pathway and Mesial Temporal Lobe Epilepsy: A Causative Link.

Introduction: Mesial temporal lobe epilepsy (MTLE) is the most frequent form of partial epilepsy. Granule cell dispersion, resulting from aberrant neuronal migration in the hippocampus, is pathognomonic of MTLE. Reelin, a secreted neurodevelopmental glycoprotein has a crucial role in controlling the radial migration of neurons. Several animal studies have implicated Reelin in the MTLE pathogenesis Mesial temporal lobe epilepsy (MTLE) is the most frequent form of partial epilepsy. Granule cell dispersion, resulting from aberrant neuronal migration in the hippocampus, is pathognomonic of MTLE. Reelin, a secreted neurodevelopmental glycoprotein has a crucial role in controlling the radial migration of neurons. Several animal studies have implicated Reelin in the MTLE pathogenesis. Methods: The aim of this study was to investigate the Reelin signalling pathway in the MTLE patients. Therefore, we studied each step in the Reelin signalling pathway for the gene and protein expressions, in the hippocampal tissue obtained from patients undergoing surgery for MTLE and compared it with age matched normal autopsy cases. Results: We found statistically significant decrease (P<0.001) in the Reelin mRNA expression in MTLE patients. Among the two reelin receptors, apolipoprotein E receptor 2 (ApoER2) was significantly increased whereas very low density lipoprotein receptor (VLDLR) was decreased among the patients. Disabled 1 (Dab1), the downstream target of reelin, was found to be decreased. Dab1 in turn inhibits Cofilin, which is responsible for cytoskeletal reorganization, thus limiting aberrant neuronal migration. Statistically significant over expression of Cofilin protein was found in the patient group. Matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteases-1 (TIMP-1), both of which are involved in processing of Reelin, were down regulated in 70-85% of cases. Conclusion: The whole pathway was found to be deranged in MTLE. These results indicate that Reelin signalling pathway is disturbed at various points in the MTLE patients and might be involved in the pathogenesis & progression of MTLE. Our results extend the existing information regarding the components of the Reelin pathway and further, establish a link between pathway disturbance and MTLE.

Morpho-functional characterization of the submucosal glands at the nasopharyngeal end of the auditory tube in humans.

BACKGROUND: The auditory tube (AT), an osteocartilaginous channel, connects the nasopharynx to the middle ear cavity. At the nasopharyngeal opening of the AT, there are dense collections of submucosal glands. In a recent article, Valstar et al. proposed these nasopharyngeal tubal glands conglomerate as salivary glands, which starkly contrasts with their previously known anatomy for being a component of the respiratory tract. This study examines the contesting views regarding the taxonomical categorization of the nasopharyngeal tubal glands. MATERIALS AND METHODS: The AT glands in context were examined in human cadavers grossly, and microscopically using routine and special (Hematoxylin and Eosin [H&E] and Periodic acid-Schiff [PAS] respectively), as well as immunohistochemical (for alpha-SMA and salivary amylase) staining methods and compared with the major and minor salivary glands and the submucosal glands in the trachea. Further, a biochemical analysis was performed to detect the presence of salivary amylase in the oral and nasopharyngeal secretions of the four living human subjects, representing major salivary glands and tubal glands, respectively. RESULTS: The submucosal seromucous glands with a surface lining of respiratory epithelium were observed at the nasopharyngeal end of AT. The cells in the tubal glands showed cytoplasmic positivity for alpha-SMA, which indicated the presence of the myoepithelial cells; however, this expression was significantly lower than in the seromucous submucosal glands within the trachea. Salivary alpha-amylase was undetectable in the cadaveric tissue samples. Moreover, the amylase level in the nasopharyngeal swabs was negligible compared to the oral swabs. CONCLUSION: The anatomical location along the respiratory tract, the presence of respiratory epithelium in the overlying mucosa, their morpho-functional resemblance to the seromucous glands in the trachea, and the absence of salivary amylase strongly indicate that the tubal glands are taxonomically different from the salivary glands. Given the available evidence, their existing recognition as a part of the respiratory tract and an integral component of the AT seems more appropriate.

Expressional Study of Permeability Glycoprotein and Multidrug Resistance Protein 1 in Drug-resistant Mesial Temporal Lobe Epilepsy.

Introduction: About 30% of patients with epilepsy do not respond to anti-epileptic drugs, leading to refractory seizures. The pathogenesis of drug-resistance in mesial temporal lobe epilepsy (MTLE) is not completely understood. Increased activity of drug-efflux transporters might be involved, resulting in subclinical concentrations of the drug at the target site. The major drug-efflux transporters are permeability glycoprotein (P-gp) and multidrug-resistance associated protein-1 (MRP-1). The major drawback so far is the expressional analysis of transporters in equal numbers of drug-resistant epileptic tissue and age-matched non-epileptic tissue. Methods: We have studied P-gp and MRP-1 drug-efflux transporters in the sclerotic hippocampal tissues resected from the epilepsy surgery patients (n=15) and compared their expression profile with the tissues resected from non-epileptic autopsy cases (n=15). Results: Statistically significant over expression of both P-gp (P<0.0001) and MRP-1 (P=0.01) at gene and protein levels were found in the MTLE cases. The fold change of P-gp was more pronounced than MRP-1. Immunohistochemistry of the patient group showed increased immunoreactivity of P-gp at blood-brain barrier and increased reactivity of MRP-1 in the parenchyma. The results were confirmed by confocal immunofluorescence microscopy. Conclusion: Our results suggested that P-gp in association with MRP-1 might be responsible for the multi-drug resistance in epilepsy. P-gp and MRP-1 could be important determinants of bio availability and tissue distribution of anti-epileptic drugs in the brain which can pharmacologically inhibited to achieve optimal drug penetration to target site.

A Cost-Effective Novel Surgical Technique of Core Decompression with Bone Marrow Aspiration Concentrate: A Preliminary Cadaveric Study.

Introduction: Core decompression supplemented by stem cell incorporation is an upcoming field of research in avascular necrosis of the femoral head. Plugging the canal to avoid loss of the concentrate injected has been recognized as a crucial step to improve the efficacy of the procedure. We describe a new surgical technique that results in native bone plug formation and eliminates the need for any additional blocker. Methodology: This pilot study was performed on 4 cadaveric proximal femurs. The standard technique was used for core decompression and bone marrow aspirate concentrate (BMAC) injection. Additionally, two more tracts were drilled, superolateral, and inferomedial to the primary tract. Results: No leakage of the radiopaque dye was observed from the entry point of the primary tract, ensuring its complete blockage in all 4 cadaveric proximal femurs. This was confirmed by sectioning the femur specimens which manifested bone plug formation at the confluence of the three tracts. Conclusion: Our technique is a unique and economical method of preventing leakage of BMAC through the entry point in the proximal femoral metaphysis. This may not only benefit patients but can also provide the groundwork for further research in this field.

Simple Technique Using an Additional Landmark to Reliably Identify the Trunk of Facial Nerve During Parotidectomy: a Cadaveric and Clinical Correlation Study.

The incidence of facial palsy in parotid surgeries is up to 50% transient and 17% complete facial palsy. Locating facial nerve trunk during parotid surgery can be tricky despite using the standard landmarks. During a cadaveric dissection, we came across a simple technique to identify the trunk of facial nerve which we have also tried to use it in clinical setting and found it to be useful. Parotidectomy was done in 12 cadaveric hemi-faces. The distance between the mastoid tip and the tympanic segment of facial nerve was measured. The distance of the facial nerve and mastoid tip and tympanomastoid suture and facial nerve was measured. The trunk of facial nerve was found to cross the tympanomastoid sulcus-mastoid tip at around 8-10 mm from the mastoid tip in 70% of the cases. We extrapolated this information in 5 cases of parotidectomy in operative setting. We were able to identify facial nerve trunk accurately in 4/5 cases. Imaginary line connecting the mastoid tip and tympanomastoid suture can be used to locate the probable position of the facial nerve trunk reliably during parotidectomy.

Cadaver dissection for oculoplastic procedures: A beginner's guide.

The purpose of this article is to form a basic guide for beginning the cadaver dissection training programs focused on oculoplastic surgical procedures. Ours was a collaborative study between the departments of Ophthalmology and Anatomy in a tertiary care teaching institute. We formed a step-wise approach to begin the cadaver dissection focused on the oculoplastic surgical procedures. The basics of cadaver procurement, processing, and preparation for dissections were described. The operative requirements of trainees, surgical handling of cadavers, and basic oculoplastic surgical steps were discussed. The types of embalming (cadaver preservation process) and steps have been described in detail. We have emphasized the preoperative discussion about the proposed dissections using standard teachings and skull models for easier understanding. Additional helping tools like soft embalming and injectable substances for better intra-dissection understanding (intra-arterial, intravenous and orbital injections) have been described. Post-dissection cadaver handing and soft-tissue disposal protocols have also been described. Overall, the cadaver dissections provide holistic surgical learning for the residents, specialty trainees, and practitioners. This article may act as a basic step-wise guide for starting the cadaver-based oculoplastics lab dissection in various institutes and workshops.

Revisiting the surgical anatomy of the triangle of doom and the triangle of pain.

Better understanding of the surgical anatomy of the triangle of doom and the triangle of pain with fixed bony landmarks like the anterior superior iliac spine (ASIS) and the pubic symphysis (PS) can help in defining a safe location for trocar placement during laparoscopic surgeries and minimize neurovascular complications. Ten cadavers were dissected bilaterally to explore the surgical anatomy of both the triangles. ASIS and PS were evaluated in relation to the deep inguinal ring, external iliac artery, femoral nerve, and inferior epigastric artery. The deep inguinal ring was located at a depth of ~3 cm, about 4.9 ± 0.56 cm along the y-axis and 6.2 ± 0.94 cm along the x-axis, from the ASIS. The external iliac artery was located ~4.33 ± 0.6 cm along the y-axis and 7.29 ± 0.76 along the x-axis from the ASIS. The inferior epigastric artery was at ~4.31 ± 0.38 cm from the midline at the level of ASIS. This knowledge can help in the surface localization of both the triangles and prevent injury to the various neurovascular structures in relation to these triangles. In the current study, cranial to the ASIS lying at a distance of >5 cm from the midline was observed to be a safe zone for accessory trocar placement. The umbilical port has been observed to be safe for trocar placement. The mean angle between ductus deferens and testicular vessels was observed to be 43.5° ± 4.79°, which could help in determining their relative locations during various surgical procedures.

Osseous deficiencies, pockets, superfluous lateral border thickening in scapula: a rare occurrence.

BACKGROUND: Beyond the nutrient and suprascapular foramen, the other foramina, holes or osseous deficiencies, pockets has rarely been reported in scapula. If present, the bony holes or deficiencies may lead to radiolucent areas and may be mistaken for sites of osteolytic destruction related to skeletal metastases, multiple myeloma or others. CASE REPORT: In the present case of left scapula, unusual osseous deficiencies of different size and shape along with pockets were observed in the body of scapula. The maximum height and width of largest bony deficiency was 35.8 mm and 12.6 mm. There was abnormal osseous thickening beside the lateral border of scapula along with the presence of some spines. Five nutrient foramina, three on the costal and two on the dorsal surface were noticed. CONCLUSIONS: The present case reports the osseous deficiencies, pockets and extra osseous growth along the lateral border, multiple nutrient foramina altogether in one specimen. Thorough anatomical knowledge of these unusual osseous variations can provide the clinicians, radiologists and forensic experts with better clinical judgement and may add insight to the surgical planning by orthopaedic surgeons.

The anatomy of the cystic duct and its association with cholelithiasis: MR cholangiopancreatographic study.

The aims of this article are to detail the anatomy of the cystic duct in patients with and without gallstones as it relates to maneuvering of the duct during endoscopic transpapillary gallbladder cannulation, and to elucidate its role in the dynamics of bile flow during gallbladder contraction. One hundred MRCPs were retrieved from the prospectively maintained radiology data system to assess the configuration of the cystic duct and its confluence vis-a-vis the main biliary duct. The configuration of the cystic duct was broadly classified into four types: Angular (44%), Linear (40%), Spiral (11%), and Complex (5%). The level of emergence of the cystic duct from the bile duct was proximal in 29%, middle in 49% and distal in 20%. Its direction from the bile duct was to the right and angled upward in 69%, right and angled downward in 15%, left and angled upward in 13%, and left and angled downward in 1%. Its orifice was on the lateral surface of the bile duct in 50%, posterior in 19%, anterior in 15% and medial in 14%. In two cases, the cystic duct opened directly into the duodenum. Tortuous cystic ducts and non-lateral unions with the bile duct were significantly more prevalent in gallstone cases than the non-gallstone group (p = 0.02). The present study details the spatial anatomy of the cystic duct vis a vis the main biliary duct. This has not been well investigated to date but has become increasingly relevant with the advent of recent gallbladder interventions.

CCR4+ monocytic myeloid-derived suppressor cells are associated with the increased epithelial-mesenchymal transition in pancreatic adenocarcinoma patients.

Among all the cancer-related deaths globally, pancreatic ductal adenocarcinoma (PDAC) accounts for the seventh leading cause of mortality. A dysregulated immune system disrupts anti-tumor immunity by abnormal accumulation of myeloid-derived suppressor cells (MDSCs), but the underlying mechanisms are still inconclusive. To gain new insights into the role of MDSCs in tumor settings, we aimed to determine the mechanism of expansion of various subsets of MDSCs in PDAC patients and their role in promoting invasiveness. We assessed the load of MDSCs, chemokines responsible for the recruitment of MDSCs in PDAC patients by flow cytometry. We investigated the chemokine profile of tumor tissue using qRT-PCR and the status of epithelial-mesenchymal transition (EMT) related markers E-Cadherin, N-Cadherin, Snail, and ZEB1 by qRT-PCR and immunohistochemistry. We found a higher frequency of tumor infiltrated MDSCs in PDAC patients. Chemokine ligands CCL2 and the receptor CCR4 were markedly elevated in the PDAC tumor, while CCR4+ monocytic MDSCs (M-MDSCs) were found significantly elevated in peripheral blood and tumor tissue. In tumor tissue, expression of E-Cadherin was significantly reduced, while N-Cadherin, Snail, and ZEB1 were markedly raised. The frequency of CCR4+ M-MDSCs significantly correlated with the expression of mesenchymal transition markers N-Cadherin, Snail, and ZEB1. Collectively, these results suggest that the CCL2-CCR4 axis plays a crucial role in driving the recruitment of M-MDSCs, which is associated with increased invasiveness in PDAC. This study sheds light on the expansion mechanism of MDSCs, which can serve as a crucial target of future anti-cancer strategies to inhibit tumor cell invasiveness.

Digastric musculus sternalis.

PURPOSE: To report a rare variant muscle. METHODS: Aberrant muscle was observed in the anterior chest wall musculature during routine cadaver prosection. RESULTS: Musculus sternalis consisting of two muscular bellies united at an angle by an intermediate tendon was observed anterior to the pectoral major of the left side. The muscle did not have any bony attachment. CONCLUSIONS: The present case represents a hybrid muscle with superior belly derived from the prepectoral mass and inferior belly from ventral longitudinal muscle column. Clinically, the musculus sternalis may be misinterpreted as a pathological mass or lesion thus its accurate knowledge is significant to radiologists, angiologists and surgeons for better interpretation of mammographic images, safer interventions and for reconstructive surgeries.

Senescent chondrogenic progenitor cells derived from articular cartilage of knee osteoarthritis patients contributes to senescence-associated secretory phenotype via release of IL-6 and IL-8.

OBJECTIVES: Despite the presence of chondrogenic progenitor cells (CPCs) in knee osteoarthritis patients they are unable to repair the damaged cartilage. This study aimed to evaluate the oxidative stress, cellular senescence, and senescence-associated secretory phenotype (SASP) in the CPCs derived from osteoarthritic cartilage and compare with the CPCs of healthy articular cartilage. METHODS: Isolated CPCs were characterized based on phenotypic expression of stem cell markers, clonogenicity, and tri-lineage differentiation assay. Production of ROS was measured using DCFDA assay. Cellular senescence in CPCs was assessed by senescence-associated beta-galactosidase assay and expression of senescence markers at the gene level using real-time PCR. Morphological features associated with senescent OA-CPCs were studied using scanning electron microscopy. To study SASP, the production of inflammatory cytokines was assessed in the culture supernatant using a flow-cytometer based cytometric bead array. RESULTS: OA-CPCs exhibited elevated ROS levels along with a relatively high percentage of senescent cells compared to non-OA CPCs, and a positive correlation exists between ROS production and senescence. The morphological assessment of senescent CPCs revealed increased cell size and multiple nuclei in senescent OA-CPCs. These results were further validated by elevated expression of senescence genes p16, p21, and p53. Additionally, culture supernatant of senescent OA-CPCs expressed IL-6 and IL-8 cytokines indicative of SASP. CONCLUSIONS: Despite exhibiting similar expression of stem cell markers and clonogenicity, CPCs undergo oxidative stress in diseased knee joint leading to increased production of intracellular ROS in chondrogenic progenitor cells that support cellular senescence. Further, senescence in OA-CPCs is mediated via the release of pro-inflammatory cytokines, IL-6 and IL-8.

Identification of novel pulmonary vein nodes as generators of ectopic arrhythmic foci for atrial fibrillation: an immunohistochemical proof.

PURPOSE: The atrial muscle sleeve (AMS) of the pulmonary vein is the most common source of the arrhythmogenic triggers in atrial fibrillation (AF). Anatomical substrate generating these ectopic currents is still elusive. The present study was designed to study the AMS of pulmonary veins with an emphasis on the structural basis which might govern AF initiation and perpetuation. METHODS: The study was conducted on a longitudinal tissue section of pulmonary vein, taken from 15 human cadaveric nondiseased hearts. Tissue was studied histologically using H&E and Gömöri trichrome stain. The pacemaker channels were identified by immunohistochemistry using monoclonal HCN4 and HCN1 antibodies. RESULTS: The AMS was identified in each pulmonary vein, located between the tunica adventitia and tunica media. A node-like arrangement of myocytes was seen within the AMS in 30% of veins. It had a compact zone limited by a fibrous capsule and contained much smaller, paler and interconnected myocytes. Outside the capsule, there was a zone of dispersed, singly placed myocytes separating the compact zone from the working myocytes of the AMS. HCN4 and HCN1 antibodies were expressed on the cell membrane of nodal myocytes, while the working myocytes demonstrated none to minimal staining. CONCLUSION: Pulmonary veins nodes are similar to the specialized cardiac conductive tissue in the histological arrangement of compact and transitional zones, cellular characteristics and the presence of pacemaker channels. They might be the anatomical basis of ectopic arrhythmogenic foci. To our knowledge, these nodes are being described for the first time in human.

Basilar Artery Bands: Anatomic and Histologic Study with Application to Coiling and Stenting Procedures.

BACKGROUND: Internal bands of the basilar artery (BA) have been rarely studied. Because bands could have obvious consequences in patient diagnosis and care, the present multiinstitutional cadaveric study was performed. METHODS: The intraluminal bands of BAs were studied in 80 cadaveric specimens derived from India (Group 1) and the United States (Group 2). Their orientation within the vessel was recorded. Measurements included the length of the BA, diameter of the BA, intraluminal band length and thickness, and distance of the band to the vertebrobasilar junction. Selected bands were submitted for histologic analysis. RESULTS: In Group 1, an intraluminal band (all vertically oriented) was identified in 16.6%. The mean length and thickness of the bands were 2.04 mm and 1.33 mm, respectively. These bands were located at a mean distance of 1.74 mm superior to the vertebrobasilar junction. In Group 2, an intraluminal band was identified in 6%. One band was vertically positioned, and 2 were horizontally positioned. The mean length and thickness of the bands were 2.5 mm and 0.9 mm, respectively. These latter bands were located at a mean distance of 2.23 mm superior to the vertebrobasilar junction. Histologically, the bands were essentially extensions of the tunica media and interna of the artery. CONCLUSIONS: To our knowledge, this study is the first multiethnic study of the prevalence and morphometry of the BA bands. A better understanding of these bands may help reveal their relationship to thrombus and aneurysmal formation and their impact on endovascular procedures.

Effect of ageing on microstructure and fracture behavior of cortical bone as determined by experiment and Extended Finite Element Method (XFEM).

Bone fracture is a severe health concern; therefore, understanding the causes of bone fracture are crucial. This paper investigates the microstructure and fracture behaviour of cadaveric cortical bone of two different groups (Young, n= 6; Aged, n=7). The microstructure is obtained from µ-CT images, and the material parameters are measured with nanoindentation. Fracture behaviour in transverse and longitudinal orientations is investigated experimentally and numerically. The results show that the Haversian canal (HC) size increases and the osteon wall thickness (OWT) decreases significantly in the aged group, whereas a nonsignificant difference is found in tissue properties. The crack initiation (Jic) and crack growth (Jgrow) toughness of the aged group are found to be significantly lower (p<0.01) than the young group in the transverse orientation; however, for the longitudinal orientation, only the value of Jic in the aged group is found significantly lower. Further, a 4-phase XFEM (based on micro-CT image) model is developed to investigate the crack propagation behaviour in both orientations. For the transverse orientation, results show that in the aged group, the crack initially follows the cementline and then penetrates the osteon, whereas, in the young group, it propagates along the cementline. These results are in agreement with experimental results where the decrease in Jgrow is more significant than the Jic in the aged group. This study suggests that ageing leads to a larger HC and reduced OWT, which weakens the crack deflection ability and causes fragility fracture. Further, the XFEM results indicate that the presence of a small microcrack in the vicinity of a major crack tip causes an increase in the critical stress intensity factor.

Virtual thanks giving to a cadaver by medical students exposed to learning anatomy before and amidst COVID-19 pandemic.

PURPOSE: Due to COVID-19 pandemic, Thanks giving ceremony to cadaver was different this year in two ways: the students were partially exposed to cadaveric dissections (for 7 months) and later learned Anatomy via online classes due to lockdown (for 5 months) and secondly it was not feasible to gather for the ceremony so virtual platform was preferred. The purpose of this study was to discern the gratitude for cadaver and to recognize the importance of cadaveric dissection from the reflection of students who experienced hybrid anatomy learning amidst COVID-19. METHODS: The study was conducted on 48 first year medical students who were admitted to the college in August 2019 and were willing to participate. An online invitation was sent to students to participate in virtual thanks giving to cadaver ceremony on the last day of their anatomy class (August 2020). RESULTS: Though the students partially studied gross anatomy with the aid of dissections on the cadaver; however, they expressed respect and gratitude to the silent mentor in the form of a card, poem, drawing or paragraph and shared it via google classroom platform. The students wished if they could continue their anatomy course in dissection hall as paused due to COVID-19 pandemic. CONCLUSIONS: Reflection of these students may mark impact on future anatomy students who may or may not get the chance for dissections. The thanks-giving gesture will also help to bind medical science and humanity especially during the crisis of pandemic.

Cadaveric anatomy of the lumbar triangular safe zone of Kambin's in North West Indian population.

A three dimensional triangular space 'the Kambin's triangle (KT)' present on the dorsolateral aspect of the intervertebral disc, is considered to be a safe area for transforaminal approaches. It allows access to the exiting and traversing nerve roots, the thecal sac and to the intervertebral disc spaces. Our aim was to calculate the area of the triangle by measuring the height and base at all the intervertebral spaces bilaterally in the lumbar region in North West Indian cadavers and to assess the diameter of circle inscribed within this triangle which will correspond to the size of cannula inserted for the minimally invasive transforaminal approaches in this population. Five randomly chosen adult cadavers were used for this study. After clearing the area, the exiting nerve was identified. The height and base of the bony KTs (n=40) were measured with the help of digital Vernier's calliper (accuracy 0.02 mm) to calculate the area of the KT. There is a steady increase in the area of the bony KT reaching maximum at the level of L4-5 intervertebral space. Statistically there were no differences in the calculated areas between right and left side. The mean diameter of inscribed circle within the triangle also showed gradual increase from 5.82 mm at L1-2 level, reaching maximum value of 7.26 mm at L4-5 level on the right side while on the left side the values were 5.66 mm and 8.16 mm respectively. Careful anatomical consideration is of utmost importance in transforaminal approaches during surgical or interventional procedures in this region. Cannula having external diameter ranging 6-8 mm is recommended for any interventional approach through Kambin's space.