Structural basis of DNA polymerase θ mediated DNA end joining.

DNA polymerase θ (Pol θ) plays an essential role in the microhomology-mediated end joining (MMEJ) pathway for repairing DNA double-strand breaks. However, the mechanisms by which Pol θ recognizes microhomologous DNA ends and performs low-fidelity DNA synthesis remain unclear. Here, we present cryo-electron microscope structures of the polymerase domain of Lates calcarifer Pol θ with long and short duplex DNA at up to 2.4 Šresolution. Interestingly, Pol θ binds to long and short DNA substrates similarly, with extensive interactions around the active site. Moreover, Pol θ shares a similar active site as high-fidelity A-family polymerases with its finger domain well-closed but differs in having hydrophilic residues surrounding the nascent base pair. Computational simulations and mutagenesis studies suggest that the unique insertion loops of Pol θ help to stabilize short DNA binding and assemble the active site for MMEJ repair. Taken together, our results illustrate the structural basis of Pol θ-mediated MMEJ.

Prehospital Treatment of Atrial Fibrillation: Infusion Pump for Bolus and Infusion?

OBJECTIVE: The prehospital treatment for stable patients with atrial fibrillation with rapid ventricular response is rate-controlling agents such as calcium channel blockers, often diltiazem given as a bolus. At our agency we encourage the use of a bolus given via the infusion pump over two to four minutes immediately followed by a maintenance infusion, given concerns of recurrent tachycardia or hypotension secondary to rapid bolus administration. We examined if administering a bolus and infusion via an infusion pump shows better heart rate (HR) control at arrival to the emergency department (ED) compared with administration of a bolus only, while maintaining hemodynamic stability during transport. We also analyzed if a patient received a second bolus within 60 min of arrival to the ED. METHODS: We used a retrospective propensity-matched cohort of prehospital patients with atrial fibrillation for whom diltiazem was administered, from 1/1/2018 to 12/31/2021, in our system of 10 New Jersey paramedic units. We analyzed the age, gender, and initial HR and used it to match groups. We analyzed the mode and time of administration, dosage of the bolus, and presence of hypotension prehospitally. RESULTS: The matched groups contained 145 patients who received a prehospital diltiazem bolus only (BO) and 146 patients who received a diltiazem bolus and infusion (BI). There was no significant difference between the mean change in HR from initial paramedic arrival to ED arrival between the two groups (BO 38 vs. BI 34, p = 0.16). There was no significant difference in the need for a second bolus within the first 60 min of arrival to the ED (BO 9.7% vs. BI 11.6%, p = 0.30). Patients in the BO group were more likely to experience prehospital hypotension then in the BI group (BO 17.2% vs BI 8.2%, p = 0.01), despite receiving smaller initial bolus doses (BO 14.2 mg vs. BI 17.4 mg, p < 0.001). CONCLUSION: Our results show no significant differences in HR control or need for repeat bolus at the ED with the use of a diltiazem infusion following a diltiazem bolus. However, even when administering larger boluses, the use of an infusion pump resulted in less hypotension.

RbgA ensures the correct timing in the maturation of the 50S subunits functional sites.

RbgA is an essential protein for the assembly of the 50S subunit in Bacillus subtilis. Depletion of RbgA leads to the accumulation of the 45S intermediate. A strain expressing a RbgA variant with reduced GTPase activity generates spontaneous suppressor mutations in uL6. Each suppressor strain accumulates a unique 44S intermediate. We reasoned that characterizing the structure of these mutant 44S intermediates may explain why RbgA is required to catalyze the folding of the 50S functional sites. We found that in the 44S particles, rRNA helices H42 and H97, near the binding site of uL6, adopt a flexible conformation and allow the central protuberance and functional sites in the mutant 44S particles to mature in any order. Instead, the wild-type 45S particles exhibit a stable H42-H97 interaction and their functional sites always mature last. The dependence on RbgA was also less pronounced in the 44S particles. We concluded that the binding of uL6 pauses the maturation of the functional sites, but the central protuberance continues to fold. RbgA exclusively binds intermediates with a formed central protuberance and licenses the folding of the functional sites. Through this mechanism, RbgA ensures that the functional sites of the 50S mature last.

Ribosomal subunits in bacteria assemble according to energy landscapes comprised of multiple parallel pathways. In this study, the authors identified a critical maturation step in the late assembly stages of the large 50S ribosomal subunit in bacteria. This step represents a merging point where all parallel assembly pathways of the ribosomal particles converge. At this critical step, the convergent assembly intermediate that accumulates in cells exists in a 'locked' state, and its maturation is paused. The RbgA protein acts on this critical step to 'unlock' the last maturation steps involving folding of the functional sites. Through this mechanism, RbgA ensures that the functional sites of the 50S mature last.

2D QSAR, Design, and in Silico Analysis of Thiophene-Tethered Lactam Derivatives as Antimicrobial Agents.

BACKGROUND: A very high rate of resistance causes health-care-associated and community-acquired infections. E. coli is one of the nine pathogens of highest concern to most of the antibiotics and other class of antimicrobials. OBJECTIVE: The objective of the present study is to develop novel thiophene derivatives using 2D QSAR and in silico approach for E. coli resistance. METHODS: Substituted thiophene series reported by Nishu Singla et al., were taken for QSAR analysis. From the results, a set of 15 new compounds were designed. A complete in silico analysis has been done using PADEL, Autodock vina, Swiss ADME, Protox II software. RESULTS: The designed compounds obey the Lipinski's rule of five and were known to have excellent inhibitory action (pIC50 values -0.87 to -1.46) which is similar to the most active compound of the data set (pIC50 -0.69) taken for the study. The bioavailability score (0.65) with no toxicity representing that the designed compounds are suitable for oral administration. CONCLUSION: The designed compounds are inactive for mutagenicity and cytotoxicity and ADMET studies states that these molecules are likely to be orally bioavailable and could be easily transported, diffused, and absorbed. So, the designed compounds will definitely serve as a lead antibacterial agent for E. coli resistance.

Enteroaggregative E. coli Adherence to Human Heparan Sulfate Proteoglycans Drives Segment and Host Specific Responses to Infection.

Enteroaggregative Escherichia coli (EAEC) is a significant cause of acute and chronic diarrhea, foodborne outbreaks, infections of the immunocompromised, and growth stunting in children in developing nations. There is no vaccine and resistance to antibiotics is rising. Unlike related E. coli pathotypes that are often associated with acute bouts of infection, EAEC is associated with persistent diarrhea and subclinical long-term colonization. Several secreted virulence factors have been associated with EAEC pathogenesis and linked to disease in humans, less certain are the molecular drivers of adherence to the intestinal mucosa. We previously established human intestinal enteroids (HIEs) as a model system to study host-EAEC interactions and aggregative adherence fimbriae A (AafA) as a major driver of EAEC adherence to HIEs. Here, we report a large-scale assessment of the host response to EAEC adherence from all four segments of the intestine across at least three donor lines for five E. coli pathotypes. The data demonstrate that the host response in the duodenum is driven largely by the infecting pathotype, whereas the response in the colon diverges in a patient-specific manner. Major pathways altered in gene expression in each of the four enteroid segments differed dramatically, with responses observed for inflammation, apoptosis and an overwhelming response to different mucin genes. In particular, EAEC both associated with large mucus droplets and specific mucins at the epithelial surface, binding that was ameliorated when mucins were removed, a process dependent on AafA. Pan-screening for glycans for binding to purified AafA identified the human ligand as heparan sulfate proteoglycans (HSPGs). Removal of HSPG abrogated EAEC association with HIEs. These results may mean that the human intestine responds remarkably different to distinct pathobionts that is dependent on the both the individual and intestinal segment in question, and uncover a major role for surface heparan sulfate proteoglycans as tropism-driving factor in adherence and/or colonization.

Thoracoscopic enucleation of oesophageal submucosal tumours in prone position gives excellent long-term outcome: A single-centre experience.

Background: Thoracoscopic enucleation of oesophageal leiomyomas has been adopted by many centres. The procedure when performed in prone position gives good results. The long-term outcome has not been reported earlier. This single-centre study establishes the role of this particular technique. Methods: A retrospective analysis of a prospectively maintained hospital database was performed and after following the study criteria eleven cases of oesophageal submucosal tumours were included in the study. All patients underwent thoracoscopic enucleation in the prone position by a single surgeon. Peri-operative data were recorded and patients followed up for a mean period of 78 months (range = 24-120 months). Results: Thoracoscopic enucleation in prone position was done for all patients with no conversions to an open procedure. Two patients had a mucosal rent during dissection that was repaired. There was no post-operative morbidity greater than Clavien-Dindo Grade 2. Long-term follow-up is available for eight patients (73%) with no recurrence of disease or symptoms. Conclusion: Oesophageal submucosal tumours (predominantly leiomyomas) are benign neoplasms with an indolent biological behaviour and deserve a procedure that would serve the purpose of minimal post-operative morbidity coupled with excellent outcome. Thoracoscopic enucleation in the prone position provides a physiological benefit that translates into better peri-operative outcomes without compromising the long-term outcome and should be the preferred form of treatment for oesophageal submucosal tumours.

SMA syndrome: management perspective with laparoscopic duodenojejunostomy and long-term results.

BACKGROUND: Superior mesentery artery syndrome (SMAS) is a rare vasculo-anatomic occlusive pathologic entity for which a period of conservative medical management is advocated with surgery reserved for nonresponsive cases. We present our management plan that entails a single admission approach and complete rendering of medical and surgical treatment to the patient on a background of the socioeconomic and cultural trends prevalent in this geographic region. METHODS: A retrospective analysis of 22 cases of SMAS admitted in our health care system who underwent a period of preoperative conditioning followed by laparoscopic duodenojejunostomy from September 2009 to June 2019 was performed. Patients were followed up at regular intervals. RESULTS: The mean follow-up of the cohort was 41.2 months (2-108 months). The median length of stay was 6 days. The mean postoperative stay was 4.13 days. A subgroup of six patients who had severe physiological depletion required a period of preoperative optimisation. Five of the 22 (22.7%) patients suffered from postoperative complications in the form of delayed return of bowel functions. None of the patients had complications more than Clavien-Dindo grade 2 with no mortality. Long-term data are available for 19 patients (86.3%) which showed no symptom recurrence. CONCLUSION: Management of SMAS that entails an antecedent medical therapy followed by surgery can be accomplished in a single admission with good to excellent results in the intermediate and long-term follow-up. Physiologically depleted patients do require a period of intensive preconditioning but on long-term follow-up, they have excellent results.

Effect of COVID19 on prehospital pronouncements and ED visits for stroke and myocardial infarction.

OBJECTIVE: The Novel Coronavirus19 (COVID19) arrived in northern New Jersey (NJ) in early March 2020, peaked at the beginning of April, and then declined. Starting in March, some patients who called 911 and required advanced life support (ALS) may have decompensated more rapidly than would have been expected, possibly because of concomitant COVID19 infection and/or delays in seeking medical care because of fear of exposure to the virus, and social isolation. In this study, our goal was to determine if there was an increase in prehospital ALS pronouncements and a decrease in ED visits for potentially serious conditions such as MI and stroke during the peak of the COVID-19 pandemic in northern NJ. METHODS STUDY DESIGN: Retrospective cohort of prehospital patients pronounced dead by paramedics and patients with MI and stroke in the EDs of receiving hospitals of these paramedics. Study Setting and Population: Ten ground ALS units in northern NJ and nine receiving hospital EDs. Each ALS unit is staffed by two NJ-certified mobile intensive care paramedics and respond with a paramedic flycar in a two-tiered dispatch system. DATA ANALYSIS: We identified prehospital pronouncements using the EMSCharts electronic record (Zoll Medical, Chelmsford, Massachusetts). We tabulated the number of pronouncements by week from January 1 to June 30 in 2019 and 2020. We tabulated the combined total number of pronouncements and ED visits by month along with visits for MI and stroke and calculated the changes during the same timeframe. We used Chi-square to test for statistical significance for the monthly changes from 2019 to 2020. RESULTS: For January through June in 2019 and 2020, there were 12,210 and 13,200 ALS dispatches, and 366 and 555 prehospital pronouncements, respectively. In 2020, pronouncements rose from a weekly baseline of 13 in early March, reached a peak of 45 at the beginning of April, then returned to the baseline level by the end of May. April 2020, the month with the most pronouncements, had 183% more pronouncements than April 2019 but total ED visits and visits for MI and stroke were 49%, 46% and 42% less, respectively (p < 0.0001 for each of these changes). CONCLUSION: Following the arrival of the COVID-19 pandemic in northern NJ, we found pre-hospital ALS death pronouncements increased and ED visits for MI and stroke decreased. Although we have speculated about the reasons for these findings, further studies are needed to determine what the actual causes were.

Structural consequences of the interaction of RbgA with a 50S ribosomal subunit assembly intermediate.

Bacteria harbor a number GTPases that function in the assembly of the ribosome and are essential for growth. RbgA is one of these GTPases and is required for the assembly of the 50S subunit in most bacteria. Homologs of this protein are also implicated in the assembly of the large subunit of the mitochondrial and eukaryotic ribosome. We present here the cryo-electron microscopy structure of RbgA bound to a Bacillus subtilis 50S subunit assembly intermediate (45SRbgA particle) that accumulates in cells upon RbgA depletion. Binding of RbgA at the P site of the immature particle stabilizes functionally important rRNA helices in the A and P-sites, prior to the completion of the maturation process of the subunit. The structure also reveals the location of the highly conserved N-terminal end of RbgA containing the catalytic residue Histidine 9. The derived model supports a mechanism of GTP hydrolysis, and it shows that upon interaction of RbgA with the 45SRbgA particle, Histidine 9 positions itself near the nucleotide potentially acting as the catalytic residue with minimal rearrangements. This structure represents the first visualization of the conformational changes induced by an assembly factor in a bacterial subunit intermediate.

Role of Era in assembly and homeostasis of the ribosomal small subunit.

Assembly factors provide speed and directionality to the maturation process of the 30S subunit in bacteria. To gain a more precise understanding of how these proteins mediate 30S maturation, it is important to expand on studies of 30S assembly intermediates purified from bacterial strains lacking particular maturation factors. To reveal the role of the essential protein Era in the assembly of the 30S ribosomal subunit, we analyzed assembly intermediates that accumulated in Era-depleted Escherichia coli cells using quantitative mass spectrometry, high resolution cryo-electron microscopy and in-cell footprinting. Our combined approach allowed for visualization of the small subunit as it assembled and revealed that with the exception of key helices in the platform domain, all other 16S rRNA domains fold even in the absence of Era. Notably, the maturing particles did not stall while waiting for the platform domain to mature and instead re-routed their folding pathway to enable concerted maturation of other structural motifs spanning multiple rRNA domains. We also found that binding of Era to the mature 30S subunit destabilized helix 44 and the decoding center preventing binding of YjeQ, another assembly factor. This work establishes Era's role in ribosome assembly and suggests new roles in maintaining ribosome homeostasis.

Thoracoscopic oesophago-oesophagostomy in the prone position for oesophageal stenosis caused by dilated azygos vein in polysplenia-associated heterotaxy.

BACKGROUND: Heterotaxy syndrome is associated with a plethora of cardiovascular and other multi-system anomalies with a high childhood mortality. A dilated azygos vein as part of the polysplenia variant of heterotaxy syndrome may cause oesophageal stenosis owing to a prolonged compression. We describe our technique of extramediastinal oesophago-oesophagostomy in the prone position for this rare congenital syndromic malformation with an excellent outcome. PATIENTS AND METHODS: A 17-year-old boy with heterotaxy syndrome presented with intermittent dysphagia and postprandial emesis with failure to thrive. Despite the presence of diverse anatomic abnormalities, it was only his symptom of dysphagia due to oesophageal stricture that merited surgical intervention. He underwent an azygos-preserving extramediastinal oesophago-oesophagostomy in the prone position without segmental resection with the establishment of continuity using a modified Collard-type anastomosis. RESULTS: The patient had an uneventful convalescence, with imaging after 1 year showing no re-stenosis. After a follow-up of 3 years, the patient is free of symptoms and has gained weight. CONCLUSION: Oesophageal stenosis may result from prolonged compression by anomalous vasculature. An isolated correctable anatomic derangement, young age with good functional reserve, other associated anomalies not causing any symptoms, the physiological advantages of executing the surgery in a prone position and availability of expertise in minimally invasive surgery ensured excellent outcomes. The hitherto unreported technique may open up avenues for further research regarding the behaviour of the oesophageal muscular tube with transection and re-anastomosis for rare benign abnormalities.

Duodenal neuroendocrine tumours in morbidly obese: Amalgamated strategy to optimise outcome.

The association of gastroenteropancreatic neuroendocrine tumours (GEP-NETs) with obesity has been reported and researched on. Rendering of a laparoscopic treatment treating these concurring pathologies in unison has not been described. Two morbidly obese patients with duodenal NETs underwent a resectional procedure, with curative intent, in the form of laparoscopic subtotal gastrectomy with roux-en-y gastrojejunostomy with partial duodenectomy and a laparoscopic one-anastomosis gastric bypass-mini gastric bypass with remnant gastrectomy and partial duodenectomy. Both patients had an uneventful convalescence with acceptable weight loss and no evidence of tumour recurrence on follow-up. The indolent nature of NETs, as compared to the morbidity of obesity provides the rationale for treating this particular cohort of patients with a surgical procedure that would serve to remove the tumour and also provide therapeutic benefit for obesity. With experience in advanced laparoscopic procedures, this can be accomplished safely with acceptable results.

Allele-Specific Silencing Ameliorates Restrictive Cardiomyopathy Attributable to a Human Myosin Regulatory Light Chain Mutation.

BACKGROUND: Restrictive cardiomyopathy is a rare heart disease associated with mutations in sarcomeric genes and with phenotypic overlap with hypertrophic cardiomyopathy. There is no approved therapy directed at the underlying cause. Here, we explore the potential of an interfering RNA (RNAi) therapeutic for a human sarcomeric mutation in MYL2 causative of restrictive cardiomyopathy in a mouse model. METHODS: A short hairpin RNA (M7.8L) was selected from a pool for specificity and efficacy. Two groups of myosin regulatory light chain N47K transgenic mice were injected with M7.8L packaged in adeno-associated virus 9 at 3 days of age and 60 days of age. Mice were subjected to treadmill exercise and echocardiography after treatment to determine maximal oxygen uptake and left ventricular mass. At the end of treatment, heart, lung, liver, and kidney tissue was harvested to determine viral tropism and for transcriptomic and proteomic analysis. Cardiomyocytes were isolated for single-cell studies. RESULTS: A one-time injection of AAV9-M7.8L RNAi in 3-day-old humanized regulatory light chain mutant transgenic mice silenced the mutated allele (RLC-47K) with minimal effects on the normal allele (RLC-47N) assayed at 16 weeks postinjection. AAV9-M7.8L RNAi suppressed the expression of hypertrophic biomarkers, reduced heart weight, and attenuated a pathological increase in left ventricular mass. Single adult cardiac myocytes from mice treated with AAV9-M7.8L showed partial restoration of contraction, relaxation, and calcium kinetics. In addition, cardiac stress protein biomarkers, such as calmodulin-dependent protein kinase II and the transcription activator Brg1 were reduced, suggesting recovery toward a healthy myocardium. Transcriptome analyses further revealed no significant changes of argonaute (AGO1, AGO2) and endoribonuclease dicer (DICER1) transcripts, and endogenous microRNAs were preserved, suggesting that the RNAi pathway was not saturated. CONCLUSIONS: Our results show the feasibility, efficacy, and safety of RNAi therapeutics directed towards human restrictive cardiomyopathy. This is a promising step toward targeted therapy for a prevalent human disease.

Mechanobiology of Macrophages: How Physical Factors Coregulate Macrophage Plasticity and Phagocytosis.

In addition to their early-recognized functions in host defense and the clearance of apoptotic cell debris, macrophages play vital roles in tissue development, homeostasis, and repair. If misregulated, they steer the progression of many inflammatory diseases. Much progress has been made in understanding the mechanisms underlying macrophage signaling, transcriptomics, and proteomics, under physiological and pathological conditions. Yet, the detailed mechanisms that tune circulating monocytes/macrophages and tissue-resident macrophage polarization, differentiation, specification, and their functional plasticity remain elusive. We review how physical factors affect macrophage phenotype and function, including how they hunt for particles and pathogens, as well as the implications for phagocytosis, autophagy, and polarization from proinflammatory to prohealing phenotype. We further discuss how this knowledge can be harnessed in regenerative medicine and for the design of new drugs and immune-modulatory drug delivery systems, biomaterials, and tissue scaffolds.

A Retrospective Database Review of the Indications, Complications, and Incidence of Subsequent Spine Surgery in 12,297 Spinal Cord Stimulator Patients.

STUDY DESIGN: Retrospective review. OBJECTIVE: To analyze the indications, incidence of minor and major complications, and rate of subsequent spinal surgery or revision after spinal cord stimulator (SCS) placement for degenerative spine disease. SUMMARY OF BACKGROUND DATA: Despite the application of SCS in various chronic pain conditions, there remains a growing debate on the efficacy and necessity of SCS in degenerative spine disease. METHODS: A nationally representative sample of Medicare patients who had an open (via laminectomy) SCS placement for degenerative spine disease between 2005 and 2014 were studied. Indications, complications, and the rate of subsequent spinal surgery within 90 days, one year, two years, and three years postoperatively were studied using Current Procedural Terminology (CPT) and International Classification of Diseases (ICD) codes. RESULTS: We included 12,297 SCS patients in our study cohort. The most common indications for SCS placement were postlaminectomy syndrome (25.2%) and chronic pain syndrome (20.2%). There was a 4.2 and 17.2% incidence of postoperative back or spine emergency department (ED) visits, and a 0.3 and 3.4% incidence of SCS electrode removal or reimplantation within 90 days and 1 year, respectively. Other reported surgical complications were wound infection (4.3%), hematoma (0.5%), and seroma (0.4%) at one year postoperatively. Within 90 days after SCS implantation, the rate of subsequent spine surgery or revision was 0.9%. This incidence was 7.1, 11.7, and 15.5% at one, two, and three years, respectively. CONCLUSIONS: In our retrospective analysis of Medicare patients, the most common indication for SCS implantation was postlaminectomy syndrome. Common postoperative complications included wound infection, and removal of SCS electrodes at one year postoperatively. About 17% patients had an ED visit for spine-related symptoms within one year of device implantation, and 15.5% underwent subsequent spinal decompression and/or fusion within 3 years after primary SCS placement.

Laparoscopic excision and redo hepaticojejunostomy for remnant choledochal cyst with anastomotic stricture in an adult: A case report.

The laparoscopic management of hepatobiliary pathology is an established mode of treatment. Incomplete excision of choledochal cyst with the resultant complications is a distinct surgical pathology, the treatment of which can be rendered based on the philosophy of minimally invasive approach which is now an acceptable treatment for the primary condition itself. We describe a case of hepaticojejunostomy site stricture associated with incomplete cyst excision managed laparoscopically. A redo procedure is technically demanding considering the presence of adhesions and a difficult to discern anatomy, but resulted in an excellent outcome. At centres with significant experience in laparoscopic surgery, redo procedures with a favourable impression on pre-operative work-up can be effectively treated with laparoscopy.

Spatial confinement downsizes the inflammatory response of macrophages.

Macrophages respond to chemical/metabolic and physical stimuli, but their effects cannot be readily decoupled in vivo during pro-inflammatory activation. Here, we show that preventing macrophage spreading by spatial confinement, as imposed by micropatterning, microporous substrates or cell crowding, suppresses late lipopolysaccharide (LPS)-activated transcriptional programs (biomarkers IL-6, CXCL9, IL-1ß, and iNOS) by mechanomodulating chromatin compaction and epigenetic alterations (HDAC3 levels and H3K36-dimethylation). Mechanistically, confinement reduces actin polymerization, thereby lowers the LPS-stimulated nuclear translocation of MRTF-A. This lowers the activity of the MRTF-A-SRF complex and subsequently downregulates the inflammatory response, as confirmed by chromatin immunoprecipitation coupled with quantitative PCR and RNA sequencing analysis. Confinement thus downregulates pro-inflammatory cytokine secretion and, well before any activation processes, the phagocytic potential of macrophages. Contrarily, early events, including activation of the LPS receptor TLR4, and downstream NF-κB and IRF3 signalling and hence the expression of early LPS-responsive genes were marginally affected by confinement. These findings have broad implications in the context of mechanobiology, inflammation and immunology, as well as in tissue engineering and regenerative medicine.

Laparoscopic evaluation and resection of type-II choledochal cyst arising from right hepatic duct mimicking gall bladder duplication.

A Type II choledochal cyst arising from the right hepatic duct may mimic a gall bladder duplication. Both are rare and may not get differentiated before operative exploration. While a magnetic resonance cholangiopancreatography (MRCP) may be helpful, laparoscopy may be the final tool for evaluation and effective surgical treatment. We report such a case of a 22-year-old male whose MRCP was suggestive of a cystic lesion in the gall bladder fossa and was taken up for surgery with a pre-operative diagnosis of gall bladder duplication with a single cystic duct. He underwent elective laparoscopic evaluation, mobilisation, discerning of anatomy and diagnosis, excision of cyst and concomitant cholecystectomy. This case highlights that these two rare entities can mimic each other on imaging; however, a laparoscopic approach serves the dual purpose of diagnosing and treating this unique pathoanatomical entity.

Coupling between chromosome intermingling and gene regulation during cellular differentiation.

In this article, we summarize current findings for the emergence of biophysical properties such as nuclear stiffness, chromatin compaction, chromosome positioning, and chromosome intermingling during stem cell differentiation, which eventually correlated with the changes of gene expression profiles during cellular differentiation. An overview is first provided to link stem cell differentiation with alterations in nuclear architecture, chromatin compaction, along with nuclear and chromatin dynamics. Further, we highlight the recent biophysical and molecular approaches, imaging methods and computational developments in characterizing transcription-related chromosome organization especially chromosome intermingling and nano-scale chromosomal contacts. Finally, the article ends with an outlook towards the emergence of a functional roadmap in setting up chromosome positioning and intermingling in a cell type specific manner during cellular differentiation.

Chromosome intermingling-the physical basis of chromosome organization in differentiated cells.

Chromosome territories (CTs) in higher eukaryotes occupy tissue-specific non-random three-dimensional positions in the interphase nucleus. To understand the mechanisms underlying CT organization, we mapped CT position and transcriptional changes in undifferentiated embryonic stem (ES) cells, during early onset of mouse ES cell differentiation and in terminally differentiated NIH3T3 cells. We found chromosome intermingling volume to be a reliable CT surface property, which can be used to define CT organization. Our results show a correlation between the transcriptional activity of chromosomes and heterologous chromosome intermingling volumes during differentiation. Furthermore, these regions were enriched in active RNA polymerase and other histone modifications in the differentiated states. These findings suggest a correlation between the evolution of transcription program in modifying CT architecture in undifferentiated stem cells. This leads to the formation of functional CT surfaces, which then interact to define the three-dimensional CT organization during differentiation.