Early Bifurcation Research Articles

TET2 regulates early and late transitions in exhausted CD8+ T cell differentiation and limits CAR T cell function.

CD8+ T cell exhaustion hampers control of cancer and chronic infections and limits chimeric antigen receptor (CAR) T cell efficacy. Targeting TET2 in CAR T cells provides therapeutic benefit; however, TET2's role in exhausted T cell (TEX) development is unclear. In chronic lymphocytic choriomeningitis virus (LCMV) infection, TET2 drove conversion from stem cell-like TEX progenitors toward terminally differentiated and effector (TEFF)-like TEX. TET2 also enforced a terminally differentiated state in the early bifurcation between TEFF and TEX, indicating broad roles for TET2 in acquisition of effector biology. To exploit the therapeutic potential of TET2, we developed clinically actionable TET2-targeted CAR T cells by disrupting TET2 via knock-in of a safety switch alongside CAR knock-in at the TRAC locus. TET2-targeted CAR T cells exhibited restrained terminal exhaustion in vitro and enhanced antitumor responses in vivo. Thus, TET2 regulates fate transitions in TEX differentiation and can be targeted with a safety mechanism in CAR T cells for improved tumor control.

Morphology and variations of middle cerebral artery: systematic review and meta-analysis.

To review morphometry, morphology, branching patterns and anomalies of middle cerebral artery (MCA). The databases of PubMed, Google Scholar and Scopus were searched with different keywords. The review comprised of 45 studies. Meta-analysis was done for dimensions of MCA, shapes, patterns and MCA anomalies. Newcastle-Ottawa Scale was used for assessment of literature. Statistical analysis was done using R software using meta package. Thirteen research were combined to determine the proportion of MCA length and pooled proportion was 16.53 cm (15.33 to 17.72 cm); I2=98%; P-value<0.01. Nine studies were combined to determine proportion of MCA diameter and pooled proportion was 2.85 cm (2.52 to 3.17 cm); I2=100%; P-value<0.05. M1 segment mean length is more on left side as compared to right side. Mean length in males (16.57±1.40 cm) is more than females (15.9±1.32 cm). Mean diameter of M1 segment is similar on both sides. Mean diameter in males (3.20±0.09 cm) is higher than females (3.14±0.18 cm). Different branching patterns observed were single trunk, early bifurcation, bifurcation, trifurcation, quadrifurcation and multiple trunks. The most typical MCA branching pattern is bifurcation. The shapes of MCA like straight shaped, U shaped, C shaped, inverted U shaped and S-shaped of M1 segment have been described. Straight MCA is the most common shape. The MCA measurements and branching pattern will assist surgeons in limiting errors in the treatment of cerebral aneurysms and infarcts and providing the best possible result for the patients. An understanding of MCA shape will aid surgeons and physicians in effective endovascular recanalization.

Temporal BMP4 effects on mouse embryonic and extraembryonic development.

The developing placenta, which in mice originates through the extraembryonic ectoderm (ExE), is essential for mammalian embryonic development. Yet unbiased characterization of the differentiation dynamicsof the ExE and its interactions with the embryo proper remains incomplete. Here we develop a temporal single-cell model of mouse gastrulation that maps continuous and parallel differentiation in embryonic and extraembryonic lineages. This is matched with a three-way perturbation approach to target signalling from the embryo proper, the ExE alone, or both. We show that ExE specification involves early spatial and transcriptional bifurcation of uncommitted ectoplacental cone cells and chorion progenitors. Early BMP4 signalling from chorion progenitors is required for proper differentiation of uncommitted ectoplacental cone cells and later for their specification towards trophoblast giant cells. We also find biphasic regulation by BMP4 in the embryo. The early ExE-originating BMP4 signal is necessary for proper mesoendoderm bifurcation and forallantois and primordial germ cell specification. However, commencing at embryonic day 7.5, embryo-derived BMP4 restricts the primordial germ cell pool size by favouring differentiation of their extraembryonic mesoderm precursors towards an allantois fate. ExE and embryonic tissues are therefore entangled in time, space and signalling axes, highlighting the importance of their integrated understanding and modelling in vivo and in vitro.

Modified Ex Vivo Renal Reconstruction to Facilitate Fenestrated-Branched Endovascular Repair of a Thoracoabdominal Aortic Aneurysm.

To report the use of modified ex vivo renal artery (RA) reconstruction in a patient with 2 small right RAs (RRAs) in anticipation of planned fenestrated-branched endovascular aortic repair (FB-EVAR) of thoracoabdominal aortic aneurysm (TAAA). A staged hybrid repair was utilized in a patient with Extent II TAAA involving celiac axis (CA), superior mesenteric artery (SMA), single left RA (LRA), and 2 small (<3 mm) RRAs. The first-stage operation consisted of hepato-renal bypass using modified ex vivo renal reconstruction with single end-to-end anastomosis to both RAs using a saphenous vein graft. A second stage FB-EVAR was performed using patient-specific manufactured stent-graft with 3 fenestrations for the CA, SMA, and LRA 6 weeks later. The patient recovered with no complications. At 4 years, the patient had widely patent hepato-renal bypass and target vessels with normal renal function. The use of adjunctive hybrid procedures may optimize or facilitate FB-EVAR. In this patient, salvage of 2 small RAs was not ideally suited for branch stenting but was possible using modified ex vivo RA reconstruction with preservation of kidney parenchyma and function. This case report illustrates a hybrid approach to overcome one of the most frequent limitations to total endovascular incorporation of renal arteries, eg small diameter, early bifurcation and multiple vessels. The modified ex vivo technique allows meticulous renal artery reconstruction without the deleterious effect of warm ischemia and without the cumbersome reconstruction of ureter and vein that is needed with traditional on table ex vivo auto transplantation. The technique is used in a minority of cases and adds the morbidity of open approach. Case selection is of paramount importance.

Bilateral Variations of Pronator Teres in the Upper Limb.

During clinical practice, physicians need to have a sound knowledge of vascular and nerve variations in the body. Patients presenting with various clinical signs and symptoms need to be thoroughly investigated with anatomic variations in mind to prevent misdiagnosis. Most nerve variations are related to their formation or their course and are frequently associated with the variability of structures that surround them. These structures most commonly include blood vessels, ligaments, and muscles. Such variations should be foremost in a physician's mind when analyzing clinical symptoms. This will aid in accurate diagnosis, and if surgical intervention is warranted, such awareness would minimize intraoperative errors. This article discusses a variation in the pronator teres muscle, the branching pattern of the brachial artery, and the median nerve. During the dissection of 11 cadaveric specimens within the Geisinger Commonwealth School of Medicine, an elderly female cadaver exhibited bilateral variations in the pronator teres muscle, which originated from the mid-humerus, instead of the medial epicondyle. Careful dissection revealed associated neurovascular variations in the arm, elbow, and forearm in relation to the muscle. The pronator teres muscles in the remaining 10 cadavers in the lab were examined for variations and their lengths were measured and compared with the cadaver under study. Unlike the normal origin at the medial epicondyle as described in textbooks, it was observed that the humeral heads of the pronator teres muscle originated at mid-humerus level bilaterally,associated with the passage of the median nerve and ulnar artery posterior to it. This muscle was 19 cm in length bilaterally, approximately 5.5 cm longer than the average lengths of pronator teres measured bilaterally in the other cadavers. The abnormally high origin of this muscle was associated with the finding of a median nerve coursing posterior to it to the forearm, failing to appear in the antecubital fossa. Although the ulnar head appeared normal, there were bilateral variations in the median nerve during its passage between the two heads of the pronator teres at the proximal forearmas it proceeded to the deeper compartment of the forearm. The brachial artery was observed to divide into radial and ulnar arteries at the mid-humerus level. The radial artery replaced the brachial artery in the antecubital fossa and the ulnar artery accompanied the median nerve posterior to pronator teres into the forearm. Such variations observed bilaterally have not yet been reported in the literature. Knowledge of these variations in the origin of pronator teres muscle, the absence of specific neurovascular structures as expected within the cubital fossa, and the awareness of early bifurcation and variation in their course can be very profound for physicians, as this region is often involved in the creation of arterio-venous fistulas for medical procedures, surgical treatment options for supracondylar and radial head fractures, and to differentiate median nerve compression in pronator teres syndrome versus carpal tunnel syndrome.

Early bifurcation of the common hepatic artery: A pitfall that should be known and recognized

Early bifurcation of the common hepatic artery (EBCHA) is a rare anatomical variation (1%), that is often overlooked but can lead to accidental ligation of the right branch of the hepatic artery with consequent arterial ischemia of the right liver and potentially very serious complications during pancreaticoduodenectomy, partial hepatectomy, or liver harvesting for transplantation. It may be difficult to diagnose EBCHA using transverse imaging sections. However, on standard CT sections with intravenous contrast injection, three warning signs should allow the image reader to suspect it: presence of two hepatic arteries to the right of the celiac trunk, presence of a retro-portal hepatic artery, and absence of a right hepatic artery arising from the superior mesenteric artery. Analysis of the CT with reconstruction then allows for definitive diagnosis and limits the risk of accidental arterial injury or ligation.

Multicentre Experience with Novel Bidirectional Double Cuffed Inner Branches for Complex Endovascular Aortic Repair

This study aimed to report the initial experience with a novel bidirectional double cuff inner branch design for incorporation of renal and mesenteric arteries in patients undergoing fenestrated and branched endovascular aortic repair (F/BEVAR). A retrospective review was undertaken of the experience of F/BEVAR with grafts integrating at least one bidirectional double cuffed inner branch implanted at three tertiary aortic centres between March 2022 and June 2023. All consecutive patients were included. Baseline characteristics, operative data, and follow up data were collected. Results were presented as number or median (interquartile range) unless otherwise stated. Thirteen patients (10 male; median age 72 [68, 77] years) had F/BEVAR using a total of 15 bidirectional double cuffed inner branches (30 cuffs). Indications for bidirectional doubled cuffed inner branches included cranial vessel orientation or double renal arteries in four patients each, common coeliomesenteric trunk in three patients, and early renal artery bifurcation, renal artery origin from a false lumen requiring a flexible route for catheterisation, and surplus configuration in one patient each. Twenty three of the 30 cuffs were used, whereas the remaining seven cuffs were intentionally occluded with vascular plugs. Target vessel incorporation was successful in all bidirectional branches. There was one technical failure related to unsuccessful catheterisation of a left renal artery targeted through a unidirectional caudal inner branch. During a median follow up of seven months there were no instances of target vessel instability or re-interventions and two patients died of causes unrelated to the bidirectional branches. The results of the use of bidirectional double cuff inner branches are promising, with high technical success and no short term branch related complications in this preliminary experience. This could potentially expand the applicability of branch endografting of complex endovascular aortic repairs, but long term results are still missing.

EVALUATION OF ANATOMICAL VARIATIONS OF EXTRARENAL RENAL ARTERIAL VASCULATURE IN VOLUNTARY KIDNEY DONORS

Objective: The present study was aimed at evaluating the variations in extrarenal renal arterial vasculature in voluntary kidney donors who had undergone Multi-Detector Computed Tomography (MDCT) renal angiography for preoperative workup. Methods: A retrospective hospital based cross-sectional study was carried out in a tertiary care Army hospital in Delhi from Jan 2019 to June 2020. All voluntary kidney donors included in the study underwent Multi-Detector Computed Tomography Angiography (MDCTA) of renal arteries as a part of routine pre-operative imaging protocol and were referred by the treating physician/surgeon for MDCTA study. Retrospective analysis of the image datasets was undertaken by the principal investigator and individual patient consent was waived off by the institutional Ethics committee. Results: The mean age of study participants was 45.9±10.2 y. Accessory renal artery was relatively more common on left side (p-value 0.001). There was statistically no significant difference between gender and the presence of accessory renal artery. There was statistically no significant difference on the comparison of side and gender with distance of segmentary bifurcation of MRA. The orthogonal diameters at the origin of the MRA and accessory renal artery on both sides were also comparable. Origin of accessory renal arteries were caudal to MRA was more frequently seen. Early segmentary bifurcation of MRA was commoner on the right side. Conclusion: The study emphasizes the importance of meticulous preoperative assessment, highlighting the need for surgeons to be cognizant of the potential variations in extrarenal renal artery anatomy. Such awareness is crucial for planning successful kidney transplant surgeries.

A Multimodal Single Cell Atlas of Adult Murine Haematopoiesis Reveals Nine Differentiation Trajectories and Epigenetic Regulatory Programs

Single cell genomics has revolutionised our understanding of differentiating systems and led to a reinterpretation of haematopoiesis, moving from a step-wise hierarchical tree model towards more continous differentiation landscapes. Recent single cell RNA sequencing (scRNA-seq) studies of Lineage- ckit+ (LK) mouse bone marrow progenitors have defined a highly granular landscape of differentiation from multipotent stem cells to committed progenitors in 8 different lineages and have served as a valuable reference landscape for comparisons with perturbation states. While these landscapes have permitted exploration and interrogation of early haematopoietic progenitors, as yet, no map of mouse total bone marrow haematopoiesis exists at single cell resolution, limiting efforts to fully understand the gene programs which specify and the cell surface phenotypes which identify maturing haematopoietic lineages nor the connection between early bifurcation decisions in progenitor cells and mature cellular outputs. To answer these questions, we performed droplet-based scRNA-seq and cell surface proteomics on whole bone marrow from 4 male and 4 female 12-week old C57Bl6 mice, using a panel of 138 antibodies against cell surface antigens. To increase representation of rare progenitor populations, we complemented total bone marrow mononuclear cells with c-kit enrichment and FACS sorted LK and LK sca1-positive (LSK) populations. After quality control filtering the single cell transcriptomes and proteomes, over 198,000 single cells were analysed separately before multimodal integration into a single UMAP embedding. Addition of cell surface proteome information to the scRNA-seq data through multimodal integration produced a representation with greater resolution of haematopoietic cell types, including improved resolution of T-cell subtypes and separation of a rare population of eosinophil progenitors which were previously indistinguishable from basophil progenitors. This integrated landscape of mouse haematopoiesis was then clustered and annotated though an iterative process of label transfer and manual annotation into 41 cell type states (Figure 1). Using cell fate analysis, which utilises transcriptional similarity and pseudotemporal ordering to estimate the probability of a single cell's commitment to defined terminal states, we were able to resolve cell fate probabilities towards nine haematopoietic lineages (erythroid, neutrophil, megakaryocyte, lymphoid, monocyte, dendritic cell (DC), plasmacytoid dendritic cell (pDC), basophil and eosinophil (Figure 2)). From these probabilities we defined nine trajectories from the earliest uncommitted progenitors to terminally differentiated populations, including a pDC trajectory involving both lymphoid and common DC progenitors. Analysis of trajectory-based gene expression trends provides a framework for discovery of lineage drivers as well as shared gene expression programs across multiple lineages. Leveraging cell surface proteome data permits the use of ‘in-silico-FACS’ to describe phenotypes of cell populations which exist at cell fate branch-points, for further in-vitro characterisation. To demonstrate the utility of our atlas as a reference, we projected perturbation datasets from 7 pre-leukaemic mouse models onto the atlas, allowing quantitation of mutation-associated cellular and tissue-scale alterations. Finally, we have leveraged the transcription-start site enrichment of 5' scRNA-seq to compute enhancer RNA (eRNA) expression in our atlas, allowing the identification of dynamic usage of specific enhancer elements during haematopoietic specification and thus providing a novel framework for correlation of eRNA expression (as a proxy for active distal chromatin regions) with gene expression trends along specific haematopoietic lineages.

Studying the role of random translocation of GLUT4 in cardiomyocytes on calcium oscillations

Defective excitation-contraction coupling (ECC) is one of the causes of contractile dysfunction linked to diabetic cardiomyopathy (DCM). This defect in ECC is mainly caused by the dysregulation of the calcium homeostasis in normal cardiomyocytes due to prolonged elevated blood glucose levels. Different types of channels inside the cardiomyocytes help maintain calcium homeostasis in the cell. Free cytosolic calcium concentration changes are one of several variables that affect complicated physiological cardiac processes and significantly impact proper heart functioning. Glucose concentration in the cardiac cell also plays a vital role in altering the calcium homeostasis in the DCM condition. In the current study, we develop a mathematical model that explicitly represents many of the known signalling components mediating translocation of the insulin-responsive glucose transporter type 4 (GLUT4) to gain insight into the complexities of metabolic insulin signalling pathways in cardiac cells. We examined the effect of the random movement of GLUT4 responsible for the entry of glucose in the cardiomyocytes. In non-paced cardiac cells calcium remains in the steady state in the absence of external pacing and avoid oscillation for healthy cardiomyocyte functioning. Intracellular calcium transients were observed during action potential. We investigated the circumstances under which the system transits from a stable state to an oscillatory state. We studied the effect of random translocation of GLUT4 on calcium oscillation. By altering system parameters, we induced insulin resistance in cardiomyocytes to mimic diabetic conditions and proposed some potential restoration strategies to restore normal calcium dynamics. Early bifurcation was observed with the introduction of randomness in the system.

Abnormal developmental trajectory and vulnerability to cardiac arrhythmias in tetralogy of Fallot with DiGeorge syndrome

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease. Ventricular dysfunction and cardiac arrhythmias are well-documented complications in patients with repaired TOF. Whether intrinsic abnormalities exist in TOF cardiomyocytes is unknown. We establish human induced pluripotent stem cells (hiPSCs) from TOF patients with and without DiGeorge (DG) syndrome, the latter being the most commonly associated syndromal association of TOF. TOF-DG hiPSC-derived cardiomyocytes (hiPSC-CMs) show impaired ventricular specification, downregulated cardiac gene expression and upregulated neural gene expression. Transcriptomic profiling of the in vitro cardiac progenitors reveals early bifurcation, as marked by ectopic RGS13 expression, in the trajectory of TOF-DG-hiPSC cardiac differentiation. Functional assessments further reveal increased arrhythmogenicity in TOF-DG-hiPSC-CMs. These findings are found only in the TOF-DG but not TOF-with no DG (ND) patient-derived hiPSC-CMs and cardiac progenitors (CPs), which have implications on the worse clinical outcomes of TOF-DG patients.

The Superior Cerebellar Artery: Variability and Clinical Significance.

The superior cerebellar artery (SCA) arises from the distal part of the basilar artery and passes by the oculomotor, trochlear, and trigeminal nerves. SCA is known to play a crucial role in the development of trigeminal neuralgia. However, due to its anatomical variability, it may also trigger other neurovascular compression (NVC), including hemifacial spasm, oculomotor nerve palsy, and ocular neuromyotonia. Additionally, it may be associated with ischemic syndromes and aneurysm development, highlighting its clinical significance. The most common anatomical variations of the SCA include duplication, a single vessel origin from the posterior cerebral artery (PCA), and a common trunk with PCA. Rarely observed variants include bifurcation and origin from the internal carotid artery. Certain anatomical variants such as early bifurcation and caudal course of duplicated SCA trunk may increase the risk of NVC. In this narrative review, we aimed to examine the impact of the anatomical variations of SCA on the NVCs based on papers published in Pubmed, Scopus, and Web of Science databases with a snowballing approach. Our review emphasizes the importance of a thorough understanding of the anatomical variability of SCA to optimize the management of patients with NVCs associated with this artery.

Assessment of morphometric parameters of middle cerebral artery using CT angiography in a tertiary care hospital.

Middle cerebral artery (MCA) favors secondaries and emboli deposition. Also, with an increase in incidence of MCA aneurysms, majorly at the M1 division point, actual standardized measurement of MCA is necessary. Thus, main aim of the study is assessment of the MCA morphometry using CT Angiography in Indian population. CT cerebral Angiography datasets of 289 patients (180 males and 109 females) were assessed for the MCA morphometry (Average age - 49.29 ± 16.16years, Range- 11 to 85years). The cases involving aneurysms and infarcts were excluded. The total length of MCA, length of M1 segment and diameter were measured and the results were statistically analysed. The mean total length of MCA, length of M1 segment and diameter were 24.02 ± 1.22mm, 14.32 ± 1.27mm, 3.33 ± 0.62mm, respectively. The mean length of M1 segment on the right and left sides was 14.19 ± 1.39mm and 14.44 ± 1.12mm, respectively and the difference was statistically significant (p ≤ 0.05). The mean diameter on the right and left sides was 3.32 ± 0.62mm and 3.33 ± 0.62mm, respectively and the difference was not statistically significant (p = 0.832). The M1 segment length was maximum in patients over 60years and diameter was maximum in young patients (20-40years). The mean length of M1 segment in early bifurcation (4.4 ± 0.65mm), bifurcation (14.32 ± 1.27mm) and trifurcation (14.15 ± 1.43mm) was also noted. The MCA measurements will be useful for surgeons to minimize errors in handling cases of intracranial aneurysms or infarcts and provide the best possible outcome to the patients.

Abstract 1513: A multi-sample study reveals the evolution and heterogeneity in high-grade serous ovarian cancer

Abstract Ovarian cancer is a heterogeneous disease and high-grade serous carcinoma (HGSC) accounts for 70% of them. The pathogenesis of HGSC had remained obscure until the identification of its tubal origin; however, the carcinogenesis process remains largely underexplored. Meanwhile, targeted therapy using poly(ADP-ribose) polymerase (PARP) inhibitors have revolutionized the treatment of HGSCs and emphasizes the importance of patient stratification. Nonetheless, current clinical trials use different assays and a consensus approach for patient stratification is still lacking. In this study, whole genome sequencing technique was used to profile tumor-normal sample pairs, including some related tumors collected from different anatomical sites. This yields a multi-sample cohort comprising 55 pre-treatment samples from 33 HGSC patients and is suitable for addressing questions about molecular stratification and tumor pathogenesis. We first recapitulated two reported HGSC subgroups (H-HRD and H-FBI) in our cohort. Comprehensive analyses were conducted on genomic scars ranging from mutations, indels, structural variants and copy numbers. Our data suggests that the genomic subgroups are characterized by different extent and onset timing of homologous recombination repair defect (HRD) as well as CCNE1 activation. Of note, H-HRD group showed higher levels of copy number-based HRD score, which often serves as a surrogate biomarker for PARP inhibitor treatment response. On the other hand, tumor evolutionary trajectory was reconstructed based on in silico methods capable of inferring relative timing of genetic alterations. This highlights an early bifurcation of carcinogenesis paths in this HGSC dichotomy, despite a common scenario of a very early TP53 mutation, an often early whole genome duplication and a chromosomal instability phenotype seen eventually. Overall, these findings corroborate the concept of tumor-intrinsic genomic phenotypes by providing mechanistic underpinnings from the aspect of tumor evolution. This provides the rationale for studying HGSC disease biology in different contexts and formulating questions about subtype-specific pathogenesis and vulnerabilities. Translationally, it also holds the promise for better identifying the patient subset that might benefit from PARP inhibitor treatment. Citation Format: Siao-Han Wong, Kai Doberstein, Frederik Marmé, Benedikt Brors. A multi-sample study reveals the evolution and heterogeneity in high-grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1513.

Variations in branching pattern of middle cerebral artery using CT angiography in South Indian population

Middle cerebral artery (MCA) variants are rare compared to that of the other two cerebral arteries. Incidence of variations like duplication, fenestration, accessory vessel and early branching ranges from 0.17 to 4%. However, the literature describing MCA variations using CT Angiography (CTA) is limited, so this study was planned to determine the incidence of MCA branching pattern in Indian population using CTA. Datasets of CTA of 578 MCA from 289 patients (180 males and 109 females), with average age of 49.29±16.16 years (range of 11 to 85 years), from a tertiary care hospital were systematically reviewed for variations in branching pattern. Cases involving aneurysms and infarcts were excluded from the study. Four branching patterns of MCA were seen. Pattern I: single trunk in 0.17% (1/578) cases, on left side. Pattern II: early bifurcation in 0.52% (2/578) cases, two cases on right and one on left side. Pattern III: bifurcation, in 97.75%, (565/578) cases, 46.15% (6/13) cases on right and 53.84% (7/13) on left side. Pattern IV: trifurcation, in 1% (6/578), two cases on right and four on left side. Duplicated MCA seen in 0.34% (2/578) cases, both on the right side. The fenestration of MCA seen in 0.17% (1/578), on the left side. No case of accessory MCA was seen. Awareness of these anatomical variations in the branching pattern of MCA is valuable for clinicians and surgeons handling cases of intracranial aneurysms and infarcts. Thus, data from this study would help surgeons minimize errors and provide the best possible outcome to the patients

Association of Early Bifurcation of Hepatic Artery With Arterial Injury in Right-Sided Living-Donor Hepatectomy: Retrospective Analysis of 500 Cases.

The aim of this study was to explore the incidence of early bifurcation of the right hepatic artery (RHA) and the right posterior hepatic artery (RPHA), which is crucial in right lobe graft (RLG) and right posterior sector graft (RPSG) procurement for living-donor liver transplantation. Early bifurcation of the hepatic artery tends to induce oversight of one of the bifurcated arteries and its injury in RLG/RPSG procurement. Unrecognizable on conventional 3-dimensional (3-D) images, its significance is underestimated. We enrolled 500 patients who underwent preoperative imaging for scheduled surgeries at two major transplant centers. All-in-one 3-D images consisting of the hepatic artery, portal vein, and bile duct were constructed. Early bifurcation of the RHA and the RPHA was defined as the arteries bifurcating proximal to the cutting line of the right hepatic duct and the right posterior duct, respectively. Early bifurcation of the RHA was seen in 11.3% of cases of an infra-portal RPHA and in 46.0% of cases of a supraportal RPHA ( P < 0.001). Early bifurcation of the RPHA was encountered in 35.3% of cases of an infra-portal RPHA, in no cases of a supra-portal RPHA, and in 100% of cases in which the arteries to segment 6/7 arose individually from the RHA. The overall incidence of early bifurcation was 19.9% for RHA and 43.6% for RPHA. Early bifurcation of the RHA and the RPHA is frequently encountered and requires caution for RLG/RPSG procurement. Special attention should be paid to supraportal RPHA for RLG procurement.

Evaluation of Clinical Implications of Renal Vessel Morphology during Renal Surgeries

Objective: Aim of this research to examine renal vessels and their morphologies as well as their clinical consequences during renal surgery. Study Design: Cross-sectional study Place and Duration: Anatomy department of Bacha Khan Medical Complex, Mardan and Multan Medical &amp; Dental College Multan during the period from April 2022 to September 2022. Methods: There were 90 cases of both genders presented in this study. Included patients were aged between 20-80 years. With suspected abdominal diseases, patients were referred for abdominal CECT examinations. In contrast-enhanced MDCT images of the Abdomen, the renal arteries were examined for their normal structure and any abnormalities. SPSS 21.0 was used to analyze complete data. Results: Males were higher in numbers 61 (67.8%) than females. Mean age of the patients was 51.3±8.43 years and mean BMI 22.4±8.42 kg/m2. We found frequency of anatomical variations of the renal vessel in 62 (68.9%) cases. Frequency of variations of the renal artery was 47 (52.2%). Among 47 cases, supplementary renal artery was found in 41 (45.6%) cases. Early bifurcation of renal artery in 15 (16.7%). In 11 patients on the right side, 12 patients on the left side, and 3 individuals on both sides, an earlier branching of the renal artery was found. The right side was more often affected by renal vein variations, with 25 (278%) patients having late renal vein confluence and 6 (6.7%) patients having additional renal veins. Patients with late renal vein confluence (3.3%) and retroaortic vein (3.3%) were seen on the left side. Conclusion: Our findings in this research show renal artery alterations are common. Endovascular, laparoscopic, and urological procedures benefit from morphological examination of the renal vessels. Keywords: Abdominal disease, Renal Artery, Conventional Angiography, Anatomical Variations

Duplicated superior cerebellar arteries, one of which was supplied by a persistent trigeminal artery variant diagnosed by magnetic resonance angiography.

The purpose of the study was to describe a case of duplicated superior cerebellar arteries (SCAs), whose caudal branch was supplied by a persistent trigeminal artery (PTA) variant, diagnosed by magnetic resonance (MR) angiography. A 74-year-old woman with a history of cerebral infarction underwent cranial MR imaging and MR angiography. MR imaging revealed chronic-stage left cerebellar and right basal ganglionic infarctions. MR angiography showed no steno-occlusive lesions in the intracranial arteries; however, duplicated left SCAs were observed and the caudal branch arose from the precavernous segment of the left internal carotid artery, which is indicative of a PTA variant. Variations of the SCA (e.g., duplication, early bifurcation, and common trunk of the posterior cerebral artery and SCA) are frequently seen. A cerebellar artery arising from the precavernous segment of the internal carotid artery without connection to the basilar artery is regarded as a PTA variant. According to a meta-analysis, the prevalence is reported to be 0.2%. The majority of PTA variants are classified as the anterior inferior cerebellar artery type. PTA and PTA variants are frequently associated with other cerebral variations. A case of duplicated posterior inferior cerebellar artery, in which one of the branches was supplied by a PTA variant, was reported previously. However, the combination of duplicated SCA and PTA variants has not been reported. Using MR angiography, the author diagnosed a case of duplicated SCA, whose caudal branch was supplied by a PTA variant. No similar case has been reported in the relevant English-language literature.

A midline retroperitoneal approach for complex abdominal aortic repair: Case description and operative technique.

In the current endovascular era, open repair of complex aortic aneurysms is becoming a rare, but indispensable, part of vascular surgeons' skill set in specific scenarios. For young, low-risk patients and patients with connective tissue disorders, early target vessel bifurcation, a horseshoe kidney, or pedunculated intraluminal aortic thrombus, fenestrated-branched stent graft technology will not be applicable without significant risks. Thus, an open surgical approach has been recommended for these patients. Most vascular surgeons will be familiar with a transperitoneal approach or a retroperitoneal approach with a lateral incision. For patients with a horseshoe kidney, an inflammatory aneurysm, or a history of multiple intraperitoneal procedures, a retroperitoneal approach should be preferred. In the present report, we have described in detail the optimization of a retroperitoneal approach through a midline incision that provides excellent exposure to the paravisceral aorta, improves exposure to the right renal artery and right iliac artery bifurcation (which is limited using the left flank retroperitoneal approach), and avoids division of the lateral abdominal wall muscles, which has often been associated with iatrogenic muscle denervation and postoperative bulging for four patients who had required complex aortic reconstruction.

A Multimodal Single Cell Atlas of Human Tonsils Reveals New Insights into T and B Cell Differentiation

Palatine tonsils are secondary lymphoid organs under constant exposure to antigens via the upper respiratory tract which makes them a compelling organ for adaptive immunity development. They represent an important niche for lymphocyte maturation, where they differentiate into a wide variety of functional states, tailoring immune responses to different insults. However, although some efforts have been made to characterise the lymphocyte maturation process in human tonsils at single cell resolution, these studies lacked cell numbers and multimodal, i.e multiomics, information to comprehensively capture the cellular heterogeneity of the process. Here we generated a comprehensive human tonsil atlas of >357,000 cells profiled across five different data modalities, such as transcriptome, epigenome, proteome, adaptive immune repertoire and spatial location. We identified 121 cell subtypes and states across lineages and characterised the maturation process of both B and T lymphocytes. The high number of profiled cells allowed the detection of rare cell subtypes, such as precursor B and T cells, the latter representing <0.01% of detected cells, supporting an ongoing maturation of lymphoid cells outside the bone marrow and thymus, respectively. Beyond these rare precursor lymphocytes, the tonsil is the niche for multiple steps of mature T and B cell differentiation. With regard to mature T cells, we described 37 different T cell (TC) subpopulations being CD4 TC the more representative population with 58,783 cells, which illustrated the maturation process of this lineage. We identified an early bifurcation following antigen recognition by naïve CD4 TC, resulting in two distinct precursor populations of T follicular helper (fh) and non-Tfh cells. Tfh precursor cells continued their differentiation trajectory towards terminally differentiated populations, with functions in the production of mature B cells (BC) and in the enhancement of antibody secretion. On the other branch of the CD4 TC differentiation trajectory, our data revealed three transcriptional Treg subtypes, with functions in the suppression of antitumor responses, COVID-19 and the control of BC antibody production, respectively. The multimodal study design further enabled the interrogation of regulatory circuits driving TC specialization, describing a potential BCL6 superenhancer specifically active in follicular TC. Intriguingly, the same region has been previously linked to BCL6 gene activation in Germinal Center (GC) BC, indicating its function as follicle-specific rather than cell type-specific cis-regulatory element. Mature B cells corresponded to the greatest population of the dataset, with >70% cells assigned to the BC lineage allowing the fine-grained description of the BC maturation process. We identified 8 distinct naïve BC (NBC) subpopulations and comprehensively characterized the activation pathway upon first antigen recognition, further expanding previous findings focused on MYC. Additionally, by the combination of gene expression and chromatin accessibility profiles we disentangled the transcription factor (TF) hierarchy associated with the Light zone (LZ) to Dark Zone (DZ) reentry. We identified the activity NF-kB family genes as one of the first determinants of the TF hierarchy that drives this specialization, which seems to be shared in LZ cells reentering the DZ as well as activated NBCs that enter the DZ for the first time. However, this regulation was not observed in LZ GCBCs that further differentiate into plasma cells (PCs). This final maturation step towards an antibody secreting phenotype was also characterized, identifying the first stages of PC precursor cells derived from either memory or LZ-GCBC and their transcriptional dynamics was also spatially mapped in the tonsillar tissue. Charting the regulatory landscape in PCs we validated the presence of described PC TFs, but we also discovered SIX5 as a novel potential TF associated with the maturation, but not the commitment, of PCs. Moreover, we identified a higher activity of the regulatory network of SIX5 in multiple myeloma. This study presents a multimodal single cell view of the TC and BC maturation process taking place in the tonsil. We not only present our analysis as a resource but we discover a yet unappreciated cellular heterogeneity as well as novel gene regulatory mechanisms driving naive towards highly specialized lymphoid cells.