Distal Loop Research Articles

Antimesenteric sleeve tapering enteroplasty with end-to-end anastomosis versus primary end-to-side anastomosis for the management of jejunal/ileal atresia

Background/objectiveSmall bowel atresia commonly causes neonatal intestinal obstructions. Technical problems are associated with the surgical management of atresia using primary end–to–end anastomosis. Furthermore, the significantly dilated proximal loop may be associated with the stasis of intestinal fluid, thus increasing pressure on the anastomosis and prolonging fasting time before initiation of oral intake. This study aimed to perform antimesenteric tapering of the proximal loop using a linear stapler to reduce its diameter and facilitate anastomosis with the distal loop. MethodsThis retrospective study included 57 neonates diagnosed with jejunoileal atresia. They were categorised into two groups: Group A (n = 29), which included neonates treated using antimesenteric sleeve enteroplasty tapering using a linear stapler and Group B (n = 28), which included neonates treated at the primary end of the proximal loop to the side of the distal loop anastomosis. ResultsThe mean operative time was 122.5 min in group A vs. 118 min in group B, and the mean duration to reach full oral intake was 17 days in group A vs. 20.2 days in group B (p = 0.03). The mean length of hospital stay was 25 and 35 days in groups A and B, respectively (p = 0.042). ConclusionTapering the proximal dilated bowel loop to achieve anastomosis with the distal loop improved the transient time, reduced stasis and its associated translocation and colonisation, and allowed for early initiation and maintenance of oral intake. All these parameters shortened the overall length of hospital stay.

S69 Case Report: Enterovesicle Fistulas and Their Presentation in Three Adolescent Males With Crohn's Disease

Case: Background: Enterovesicle fistulas (EVF) in the setting of Crohn’s disease (CD) are uncommon. The aim of this poster is to shed light on the diagnosis and management (medical vs surgical) of EVF in pediatric populations. Methods: This poster compares 3 cases of adolescent males with Crohn's disease, their continued workup, and the difference in disease course in relation to the development of EVF. Results: Case 1: A 12-year-old male with known severe ileocolonic CD diagnosed at age 8, and a history of perianal and intra-abdominal abscesses and perianal fistula experienced recurrent urinary tract infection (UTI) 2 years into his diagnosis. A urine sample revealed stool, and magnetic resonance imaging (MRI) confirmed EVF. Exploratory laparotomy revealed inflamed and structured distal ileum with pre-stenotic dilation of proximal bowel, as well as the EVF. After surgical takedown, ileocectomy, and diverting ileostomy, he was started on infliximab. He has been on infliximab for 28 months with normalization C-reactive protein, normal linear growth curve, and no further episodes of structuring or penetrating CD. Cast 2: After years abdominal pain and growth failure a 16-year-old male (now 17) was diagnosed with Crohn's ileitis. After starting Infliximab, he began complaining of sediment and pneumaturia, which was confirmed on urinalysis (UA). He was taken to surgery for diagnostic laparoscopy where his cecum was found to be adherent to the bladder. Distal loop ileostomy was created. He is currently being treated with infliximab and doing well 1-month post-operatively. Case 3: A 22-year-old male was diagnosed with Crohn’s ileitis at age 13, after presenting with abdominal pain and weight loss. Before beginning medical therapy, he experienced dysuria and pneumaturia with visible stool in his urine sample. EVF was not seen on abdominal Computed Tomography (CT) scan. His EVF was confirmed on exploratory laparotomy, and he underwent EVF take-down, ileocecectomy, and diverting ileostomy, with subsequent successful ileostomy take-down. He was started on thiopurine post-operatively and has remained in remission on therapy for 9 years without no further disease exacerbations. Conclusions: The incidence of EVF among adults with CD ranges from 2% to 5%, although little is known about pediatric patients with EVF. In fact, only 2 case reports in children exist. EVF can be the presenting symptom of CD, or patients with known CD can present with recurrent UTI leading to diagnosis. The distinct symptoms of EVF, dysuria, pneumaturia and fecouria, make it easy to diagnose with UA and confirmatory cross-sectional imaging, although little is known about common sites of connection between the bladder fistula in children and how this affects presentation and management (10). In our 3 cases, patients received surgical intervention followed by aggressive medical management. With the advent and improvement of immunotherapy medications, research in adults has shown that EVF without severe complicating CD can sometimes be treated with medical therapy alone and experience EVF resolution (2,6-9). There is no clear consensus on clinical criteria for medical vs surgical intervention (7,8) so future studies in this area are needed.

The prevention of leakage of ileo-colonic anastomosis in an experimental peritonitis

Introduction. In colon surgery, intestinal anastomotic leaks are the main contributor to postoperative mortality. The incidence of this complication in the formation of small-colonic anastomoses in urgent surgery reaches 12% or more. It is required to develop simple and reliable techniques of intestinal suturing in conditions of peritonitis.The aim of the study was to investigate the morphological events occurring in the small-colonic anastomosis formed using various options under simulated peritonitis.Materials and methods. An experimental study involved 2 groups of Wistar white rats (25 animals - the control group and 25 - the main one). Peritonitis was simulated by dissecting the ileum into circles in 5-6 cm from the ileocecal angle. A day later, a relaparotomy was performed, a section of the intestine with a defect was excised, the distal loop was tied up, a small-colonic anastomosis was formed with a proximal loop: in the end-to-side study group the intervention was performed according to the author's method (RF patent No. 2709253 dated 12/17/2019), in the control group using side-to-side anastomosis. In 6 days, anastomosis was taken from the survived animals for histological examination. Histological examination was carried out at a magnification x400 and x630. Micromorphometry was performed with the count of neutrophils, fibroblasts and measurement of the relative area of ​​blood vessels in the anastomotic suture. Fisher's exact test, Mann-Whitney test were used for statistical data processing, quantitative data were described in the median and interquartile interval format.Results. An original end-to-side anastomosis resulted in a greater number of fibroblasts and blood vessels in the muscular and submucosal layers of the intestinal wall in the suture zone than in the side-to-side anastomosis. The number of anastomotic leaks in the study group was 4 times less than in the control group.Conclusion. The use of the authors end-to-side anastomosis technique improves blood supply and repair of the suture area in a small-colonic anastomosis under 1-day simulated peritonitis; this being accompanied by a decreased incidence of anastomosis failure.

Multidisciplinary approach for ureteral stent intravascular migration: a case report

Clinical case description: We report the case of a patient who underwent a double-pigtail ureteral stent (DPS) retrograde placement, following a complicated right renal colic. After two days with persisting pain and hematuria, a CT-Scan revealed a proximal pigtail misplacement into the inferior vena cava (IVC). In a multidisciplinary approach, an endourological removal was performed, pulling the distal loop with a cystoscope, while the vascular surgery team performed femoral access and phlebography during and after the DPS removal to prevent bleeding from IVC. Abdominal access for laparotomy was ready, anticipating potential bleeding. Relevance: DPS retrograde placement is a very frequent, usually uneventful procedure, but major complications may occur, such as the one described in the present case. It is important to know the risk of intravascular misplacement of the DPS, especially in cases of bad evolution or hematuria. Conclusion: DPS intravascular migration is a rare but potentially severe complication. An early detection and a multidisciplinary collaboration between the urology and vascular surgery teams is paramount to perform a minimally invasive removal and prevent major events.

Exploring Structural Diversity among Adhesion Devices Encoded by Lactococcal P335 Phages with AlphaFold2.

Bacteriophages, or phages, are the most abundant biological entities on Earth. They possess molecular nanodevices to package and store their genome, as well as to introduce it into the cytoplasm of their bacterial prey. Successful phage infection commences with specific recognition of, and adhesion to, a suitable host cell surface. Adhesion devices of siphophages infecting Gram-positive bacteria are very diverse and remain, for the majority, poorly understood. These assemblies often comprise long, flexible, and multi-domain proteins, which limit their structural analyses by experimental approaches. The protein structure prediction program AlphaFold2 is exquisitely adapted to unveil structural and functional details of such molecular machineries. Here, we present structure predictions of adhesion devices from siphophages belonging to the P335 group infecting Lactococcus spp., one of the most extensively applied lactic acid bacteria in dairy fermentations. The predictions of representative adhesion devices from types I-IV P335 phages illustrate their very diverse topology. Adhesion devices from types III and IV phages share a common topology with that of Skunavirus p2, with a receptor binding protein anchored to the virion by a distal tail protein loop. This suggests that they exhibit an activation mechanism similar to that of phage p2 prior to host binding.

＜Editors' Choice＞ Surgical removal of an intracranially migrated acupuncture needle: a case report and literature review.

Acupuncture is a popular alternative therapy worldwide and is generally safe. However, serious acupuncture-related complications can occur. Intracranial complications caused by a migrated acupuncture needle are extremely rare. Herein we report a surgical case of intracranial acupuncture needle migration and discuss the key technical aspects of the procedure. We additionally performed a review of the relevant literature. A 55-year-old woman presented with migration of a broken acupuncture needle via the posterior cervical skin. Computed tomography (CT) showed that the needle migrated intra- and extradurally via the atlanto-occipital junction. CT angiography revealed that the needle tail was located adjacent to the right distal horizontal loop of the vertebral artery. Meanwhile, the needle tip was positioned in the premedullary cistern adjacent to the medulla oblongata via the right lateral medullary cistern. Emergent surgical removal was conducted. Intradural exploration was required as the needle was not found in the epidural space. The needle penetrated the adventitia of the right intradural vertebral artery. We failed to pull out the needle toward the epidural space. After the needle was completely pulled into the intradural space, it was successfully removed without bleeding complication. Postoperative CT showed no evidence of residual needle fragment. The patient was discharged home without any sequelae. To the best of our knowledge, this is the first case of penetrating vertebral artery injury caused by radiologically confirmed acupuncture needle migration. An intracranially migrated needle should be removed urgently to prevent further migration causing brainstem, cranial nerve, and vessel injuries. The surgical strategy should be selected according to needle location and direction.

Distinct stimulus-dependent neutrophil dynamics revealed by real-time imaging of intestinal mucosa after acute injury.

Clinical symptoms in many inflammatory diseases of the intestine are directly related to neutrophil (PMN) migration across colonic mucosa and into the intestinal lumen, yet in-vivo studies detailing this process are lacking. Using real-time intravital microscopy and a new distal colon loop model, we report distinct PMN migratory dynamics in response to several models of acute colonic injury. PMNs exhibited rapid swarming responses after mechanically induced intestinal wounds. Similar numbers of PMNs infiltrated colonic mucosa after wounding in germ-free mice, suggesting microbiota-independent mechanisms. By contrast, acute mucosal injury secondary to either a treatment of mice with dextran sodium sulfate or an IL-10 receptor blockade model of colitis resulted in lamina propria infiltration with PMNs that were largely immotile. Biopsy wounding of colonic mucosa in DSS-treated mice did not result in enhanced PMN swarming however, intraluminal application of the neutrophil chemoattractant LTB4 under such conditions resulted in enhanced transepithelial migration of PMNs. Analyses of PMNs that had migrated into the colonic lumen revealed that the majority of PMNs were directly recruited from the circulation and not from the immotile pool in the mucosa. Decreased PMN motility parallels upregulation of the receptor CXCR4 and apoptosis. Similarly, increased expression of CXCR4 on human PMNs was observed in colonic biopsies from people with active ulcerative colitis. This new approach adds an important tool to investigate mechanisms regulating PMN migration across mucosa within the distal intestine and will provide new insights for developing future anti-inflammatory and pro-repair therapies.

Structure of Klebsiella pneumoniae adenosine monophosphate nucleosidase.

Klebsiella pneumoniae is a bacterial pathogen that is increasingly responsible for hospital-acquired pneumonia and sepsis. Progressive development of antibiotic resistance has led to higher mortality rates and creates a need for novel treatments. Because of the essential role that nucleotides play in many bacterial processes, enzymes involved in purine and pyrimidine metabolism and transport are ideal targets for the development of novel antibiotics. Herein we describe the structure of K. pneumoniae adenosine monophosphate nucleosidase (KpAmn), a purine salvage enzyme unique to bacteria, as determined by cryoelectron microscopy. The data detail a well conserved fold with a hexameric overall structure and clear density for the putative active site residues. Comparison to the crystal structures of homologous prokaryotic proteins confirms the presence of many of the conserved structural features of this protein yet reveals differences in distal loops in the absence of crystal contacts. This first cryo-EM structure of an Amn enzyme provides a basis for future structure-guided drug development and extends the accuracy of structural characterization of this family of proteins beyond this clinically relevant organism.

S2489 Differentiating CMV Colitis From GVHD in Post-Transplant Patients: A Case Study

Introduction: Cytomegalovirus (CMV) infection can complicate the clinical course of immunocompromised patients including allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients, where the infection can be serious. CMV can involve different organs including lungs, brain, eyes, and the GI tract. Signs and symptoms of CMV infection may overlap with other conditions including graft-versus-host disease (GVHD), a multisystem disorder commonly seen in allo-HSCT recipients. Case Description/Methods: A 57-year-old female presented with abdominal pain and diarrhea. Past medical history included relapsed acute myeloid leukemia, treated with azacitidine and venetoclax followed by allo-HSCT. She was recently hospitalized for suspected GVHD with skin, liver, and gastrointestinal involvement. She was also found to have a CMV viral load of 920 IU/mL. Endoscopy showed diffuse inflammation across the GI tract, with biopsies revealing apoptotic bodies consistent with acute GVHD. She was treated with ruxolitinib and prednisone for GVHD, and valganciclovir prophylactically for CMV viremia. At this presentation, labs were notable for lymphocytes of 39 x103/uL and platelets of 22 x 103/uL, and CMV viral load of 1,822,242 IU/mL. CT imaging revealed thickened distal small bowel loops, cecum, and right colon, and edematous gastric walls with submucosal enhancement. Infectious work-up, including stool culture, ova/parasite, and clostridium, was negative. She underwent endoscopic evaluation; EGD showed white discoloration that washed off in the esophagus and diffuse erythematous mucosa in the stomach (Figure). Biopsies from gastric mucosa and right colon mucosa revealed focal nuclear changes. Immunohistochemical stains were positive for CMV. She was diagnosed with refractory CMV colitis and treated with maribavir with improvement of symptoms and reduction of viral load, and prior course of steroids was tapered. Discussion: Immunosuppression for GVHD has been identified as an important risk factor for CMV reactivation. Differentiating CMV colitis and GI-GVHD poses a diagnostic challenge, and endoscopic evaluation is needed to address this. Endoscopy can identify cecal ulcers, a reliable finding for CMV colitis in patients with GVHD after allo-HSCT.1 It is important to timely identify CMV colitis to prevent post-transplant morbidity and mortality. This case also demonstrates effectiveness of maribavir, a novel antiviral, for refractory post-transplant CMV colitis.Figure 1.: EGD images showing white discoloration in the entire esophagus and diffuse erythematous mucosa in the entire examined stomach.

STUDY OF INDICATIONS AND COMPLICATIONS OF SMALL AND LARGE INTESTINAL STOMAS IN EMERGENCY SITUATIONS

Background: Stoma is a surgically created opening in the anterior abdominal wall with a purpose to divert the feces away from the distal bowel loops in order to relieve obstruction or product anastomosis (1) in emergency situations. Stomas may produce multiple complications (2). Most of the stoma complications are minor, can be managed with proper care, only little complications require intervention by means of surgery which may produce high morbidity and mortality (3). To study the Aims & Objectives: various types and indications of small and large intestinal stomas in emergency situations. To identify the various early complications encountered after the construction of emergency intestinal stomas. To assess the ways in which these complications can be minimized and managed in a better way. Observational Prospective Study of 40 patients undergoi Methods: ng emergency small and large intestinal stoma construction in tertiary care government hospital from March 2020-August 2021 according to inclusion and exclusion criteria with a follow up of 3 months post-operation. Data is analyzed using descriptive statistics. Out Results & Conclusion: of 40 patients underwent emergency small and large intestinal stoma construction, males were 34 and females were 6 with mean age of 45.38 years. The most common indication for stoma construction was Intestinal obstruction followed by Enteric perforation. The most common stoma constructed was loop ileostomy followed by loop sigmoid colostomy. The most common early complication of stoma was skin excoriation followed by stoma retraction. Most stoma complications are managed conservatively.

S3369 Small Bowel Diverticulitis: A Unique Urinary Presentation

Introduction: Small bowel diverticula (SBD) are rare and often discovered incidentally. Although usually asymptomatic, complications such as diverticulitis, obstruction, abscess, and perforation can occur. Given the rarity of SBD, no established treatment guideline exists. We present a case of a healthy patient with urinary symptoms who was found to have SBD. Case Description/Methods: A healthy 54-year-old female presented to her PCP with sharp suprapubic abdominal pain with dysuria and gross hematuria. Physical examination demonstrated suprapubic tenderness upon palpation. A urinalysis and urine culture were unremarkable. However, there was concern for urinary tract infection (UTI) and patient was started on Cephalexin 500mg BID for 14 days. Two days later, patient presented to the ER with worsening symptoms. She now had associated nausea and vomiting with fever. She exhibited guarding and rebound tenderness on physical examination. A CMP was unremarkable with normal LFTs. She had a WBC count of 11.8 K/mm3. Given worsening suprapubic pain, a CT abdomen and pelvis with contrast was obtained which showed severe acute small bowel diverticulitis involving a 6 cm long distal ileal loop adjacent to the bladder. Surgery services were consulted for intervention and recommended inpatient observation and initiation of IV antibiotics. The patient refused and wished to go home. She was discharged with Ciprofloxacin 500mg BID and Metronidazole 500mg TID for 14 days. The patient was scheduled to follow up with GI clinic. A repeat CT abdomen and pelvis with contrast showed near complete resolution of the inflammatory features of small bowel diverticulitis. Patient reported retuning to her baseline health. (Figure) Discussion: Most patients with SBD are asymptomatic. However, symptoms may reflect local inflammation as seen in our patient who presented with suprapubic pain, dysuria, and gross hematuria. No established treatment guidelines exist for SBD and thus colonic diverticulitis management is used as a guide. Asymptomatic patients do not require treatment. For patients with uncomplicated SBD, management includes diet adjustment and antibiotics. For complicated SBD, as evidenced by perforation on imaging or hemodynamic instability, surgical management is often required.Figure 1.: (top): CT abd and pelvis w/contrast showing large small bowel diverticulitis measuring 2.1 cm. (bottom): CT abd and pelvis w/contrast showing marked improvement of the small bowel diverticulitis with near complete resolution of inflammatory changes and wall thickening.

S1981 Adult Intussusception: Finding a Lead on a Rare Case

Introduction: Bowel intussusception is defined as a telescoping proximal loop within the distal loop of bowel, obliterating the bowel lumen. Although over 95% of cases occur in the pediatric population; intussusception in adults is strongly associated with tumors, with malignancy rates accounting for approximately half of all adult cases. Case Description/Methods: A 37-year-old female with no known past medical history presented to the Emergency Department complaining of suddenly worsening non-localized abdominal pain and distension. She reports a 5-day history of intermittent generalized cramps abdominal pain, which causes her to wake up several times throughout the night. Associated symptoms include anorexia, non-bloody emesis, and constipation, followed by small volume loose stools. Her physical exam was significant for generalized abdominal tenderness. Initial laboratory work-up with CBC, CMP, lipase and CRP were unrevealing except for a low serum bicarbonate (19). CT abdomen with contrast demonstrated a large colonic intussusception from the ascending colon to the splenic flexure, with suggestion of a large polyp or mass in the splenic flexure as a possible lead point (Figure). The patient underwent an exploratory laparotomy with right hemicolectomy and lymphadenectomy. Pathology of the resected colon was consistent with a Plasmablastic neoplasm involving the ileocecal valve. All surgical margins and 27 resected lymph nodes were negative. Discussion: Adult intussusception is a rare cause of bowel obstruction (< 1% on adult causes) that carries a high risk of complications, if not emergently identified and treated. Nonspecific abdominal pain is the most common clinical presentation of Adult Intussusception. The triad of red current jelly stool, colicky abdominal pain, and a palpable sausage-shaped mass; classically seen with children, is rarely present in the adult presentation. Due to high rates of malignancy, adult cases are traditionally treated with a large en-bloc resection. Early diagnosis of intussusception in adults requires a high level of clinical suspicion. Failing to recognize this may lead to complications such as bowel ischemia and perforation. Treatment in adults requires urgent operative management with oncologic resection and further investigation.Figure 1.: Left: Coronal CT revealing large colonic intussusception with lead point (yellow arrow). Right: Sagittal CT demonstrating target sign (green arrow).

An Unusual Cause of a Cecal “Seesaw” and Pneumatosis Intestinalis

Question: A 66-year-old woman with history of stroke, previous hernia surgery with mesh placement, and obstructive cholestasis due to choledocholithiasis presented with 3 days of right-sided abdominal pain, 15-lb weight loss over 1 month, and 3 weeks of constipation with thin stools. Colonoscopy was normal a few months prior. Her prior episode of choledocholithiasis in 2017 led to endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy and placement of a double pig-tail stent. She was recently admitted 1 month ago for jaundice and right upper quadrant (RUQ) pain at which time magnetic resonance cholangiopancreatography showed severe intrahepatic and extrahepatic biliary duct dilation but no liver or pancreatic lesions. The cecum was nonspecifically distended and fluid filled. Esophagogastroduodenoscopy revealed a benign-appearing intrinsic duodenal stricture felt to be related to scar tissue from the previous hernia mesh surgery. ERCP revealed an occluded biliary stent that had migrated to the major papilla and a severe burden of choledocholithiasis. The occluded stent was removed, and partial removal of stones was achieved via basket extraction. A new biliary stent was placed with a plan to follow up in 4 weeks for repeat ERCP for further stone extraction and stent removal. Before this appointment she was readmitted for worsening RUQ pain. A computed tomography scan revealed dilated loops of distal small bowel and a dilated cecum that had folded anteriorly and superiorly with extensive pneumatosis. The ascending colon was also dilated up to a decompressed hepatic flexure, where nonspecific bowel wall thickening was visualized, suggesting a transition point. No obvious mass or lesion was noted at the hepatic flexure (Figure A). Despite clinical improvement with conservative management, a lower gastrointestinal series performed a few days later showed persistent severe obstruction at the hepatic flexure with bird-beak appearance (Figure B). What is the most likely explanation for these imaging findings and how should it be managed? See the Gastroenterology website (www.gastrojournal.org) for more information on submitting to Gastro Curbside Consult. The patient’s imaging findings are consistent with cecal bascule (type III cecal volvulus). Cecal bascules are the rarest variant of cecal volvulus that involve upward folding of the cecum, without axial twisting or sigmoid involvement.1Rabinovici R. Simansky D.A. Kaplan O. et al.Cecal volvulus. Dis Colon Rectum. 1990; 33: 765-769Crossref PubMed Scopus (119) Google Scholar Bascule in French means “seesaw,” describing the pathophysiology of the cecal presentation. Surgical management was indicated given the persistent and severe hepatic flexure stricture seen on lower gastrointestinal series. Exploratory laparotomy revealed numerous omental nodules and a mass was discovered in the RUQ involving the gallbladder and liver that was causing extrinsic compression of the hepatic flexure. The largest nodule was excised and confirmed a diagnosis of metastatic cholangiocarcinoma. A distal loop ileostomy was created to decompress the colon and prevent ongoing colonic obstruction. No colonic resection was necessary. The patient began cancer staging and treatment planning, but unfortunately passed 1 month after diagnosis. This is a unique case of an extrinsic malignant obstruction causing cecal bascule. The development of a cecal bascule is usually attributed to an abnormally mobile cecum due to improper development and insufficient fixation of the mesentery to the posterior parietal peritoneum. A mobile cecum may also be acquired in pregnancy due to enlargement of the uterus or after abdominal surgery, such as open appendectomies, which require extensive division of peritoneal attachments to the cecum. Clinical presentation varies with abdominal pain, distention, and nausea being the most common symptoms but can progress to an acute abdomen and perforation.2Lung B.E. Yelika S.B. Murthy A.S. et al.Cecal bascule: a systematic review of the literature.Tech Coloproctol. 2018; 22: 75-80Crossref PubMed Scopus (14) Google Scholar Diagnosis of type III cecal volvulus requires computed tomography imaging confirming a distended cecum lying anterior to ascending colon. Treatment generally involves surgical resection of the affected bowel because colonoscopic detorsion may lead to recurrence.3Le C.K. Nahirniak P. Qaja E. Cecal volvulus. StatPearls Publishing. StatPearls Website, 2021Google Scholar

Distal Hydrophobic Loop Modulates the Copper Active Site and Reaction of AA13 Polysaccharide Monooxygenases.

Polysaccharide monooxygenases (PMOs) use a type-2 copper center to activate O2 for the selective hydroxylation of one of the two C-H bonds of glycosidic linkages. Our electron paramagnetic resonance (EPR) analysis and molecular dynamics (MD) simulations suggest the unprecedented dynamic roles of the loop containing the residue G89 (G89 loop) on the active site structure and reaction cycle of starch-active PMOs (AA13 PMOs). In the Cu(II) state, the G89 loop could switch between an "open" and "closed" conformation, which is associated with the binding and dissociation of an aqueous ligand in the distal site, respectively. The conformation of the G89 loop influences the positioning of the copper center on the preferred substrate of AA13 PMOs. The dissociation of the distal ligand results in the bending of the T-shaped core of the Cu(II) active site, which could help facilitate its reduction to the active Cu(I) state. In the Cu(I) state, the G89 loop is in the "closed" conformation with a confined copper center, which could allow for efficient O2 binding. In addition, the G89 loop remains in the "closed" conformation in the Cu(II)-superoxo intermediate, which could prevent off-pathway superoxide release via exchange with the distal aqueous ligand. Finally, at the end of the reaction cycle, aqueous ligand binding to the distal site could switch the G89 loop to the "open" conformation and facilitate product release.

MECKELS DIVERTICULUM WITH MESENTERY AS A RARE CAUSE OF CLOSED LOOP OBSTRUCTION-A CASE REPORT

Meckel's Diverticulum is most common congenital anomaly of gastrointestinal tract. It arises from Antimesenteric border of the small bowel [1]. In contradiction, a case encountered at our institution where a 32-y old female presented with complaints of pain abdomen since 3 days, vomiting's since 3 days, obstipation since 3 days and distention since 1 day. On examination abdomen is distended, diffuse tenderness present all over the abdomen with no bowel sounds and collapsed rectum with no fecal staining per rectally. Imaging studies on ultra-sonography shown dilated small bowel loops with max diameter of 3.1cm showing to and fro peristalsis. On CT abdomen multiple dilated small bowel loops with air uid levels with maximum diameter of 4.1cms with collapsed terminal ileum and large bowel. ?Closed Loop Obstruction. Emergency exploratory laparotomy was planned and shown Meckel's diverticulum with mesentery present on anti-mesenteric border with mesentery extending from mesenteric border to tip of Meckel's diverticulum with internal herniation of proximal ileum between the Meckel's and its mesentery causing closed loop obstruction noted at 60cms from IC junction for which herniated bowel loops was released with diverticulectomy followed by anastomoses of proximal and distal ileal loops. Resected Meckel's sent for histopathological examination and cut section showed mucosa, sub-mucosa, muscularis propria and serosa. Mucosa shows chronic nonspecic inammation, sections from the adjacent area's shows hyperplastic mucosa, hypertrophied muscularis layers and serosa with congested blood vessels with feature's consistent with Meckel's diverticulum. Patient was followed for 6 months, and the course was un-eventful.

Complications of Colostomy Reversal in Patients with Imperforate ANUS

Background: Colostomy reversal after definitive procedure in patients of Imperforate Anus (for example; PSARP) can be difficult and challenging for surgeon due to proximal and distal gut lumen discrepancy, short length of distal loop, difficult mobilization of stoma. These factors affect the anastomosis and anastomosis is done under tension due to these factors. Colostomies which are reversed under tension mostly results in anastomosis leakage and increases the morbidity and mortality rate. The objective of this study to assess postoperative outcome in terms of complications following colostomy closure in patients with imperforate anus. Material and Methods: This is a prospective study done at the Department of Pediatric Surgery, National Institute of Child Health Karachi during the period of 6months from December 2016 to June 2017. A Self- structured performa was used to collect the data of total 84 Patients who Underwent Colostomy Reversal after definitive procedure for imperforate anus . Data analyzed through SPSS version 20. A descriptive statistical analysis of continous and categorical variables were performed. Continuous data (like age) expressed as mean SD. The categorical data like gender, wound infections , anastomosis leakage expressed in frequency and percentages. Results: Out of total 84 children, majority 51 (60.7%) children were presented with ≤4 years of age (Mean age 4.15±3.12 years). Majority 55 (65.5%) children were presented with &gt;8 kg of weight (Mean weight 13.31±6.00 kg). There were 41 (48.8%) males and 43 (51.2%) females. Intra-operative difficulty was found in 55 (65.5%) children. Postoperative complication showed that wound infections were observed in 10 (11.9%) children while frequency of anastomotic leakage was found in 12 (14.3%) children. Conclusion: Anastomotic leakage was found to be higher following colostomy closure in children with intra-operative difficulty due to proximal and distal gut lumen discrepancy, short length of distal loop and dense adhesions making difficult the mobilization of stoma. Keywords: Postoperative outcome, Complications, Colostomy closure, Imperforate anus

MRNA-encoded HIV-1 Env trimer ferritin nanoparticles induce monoclonal antibodies that neutralize heterologous HIV-1 isolates in mice.

The success of nucleoside-modified mRNAs in lipid nanoparticles (mRNA-LNP) as COVID-19 vaccines heralded a new era of vaccine development. For HIV-1, multivalent envelope (Env) trimer protein nanoparticles are superior immunogens compared with trimers alone for priming of broadly neutralizing antibody (bnAb) B cell lineages. The successful expression of complex multivalent nanoparticle immunogens with mRNAs has not been demonstrated. Here, we show that mRNAs can encode antigenic Env trimers on ferritin nanoparticles that initiate bnAb precursor B cell expansion and induce serum autologous tier 2 neutralizing activity in bnAb precursor VH + VL knock-in mice. Next-generation sequencing demonstrates acquisition of critical mutations, and monoclonal antibodies that neutralize heterologous HIV-1 isolates are isolated. Thus, mRNA-LNP can encode complex immunogens and may be of use in design of germline-targeting and sequential boosting immunogens for HIV-1 vaccine development.

Aquaporin (AQP) channels in the spiny dogfish, Squalus acanthias II: Localization of AQP3, AQP4 and AQP15 in the kidney.

Three aquaporin water channel proteins, AQP3, AQP4 and AQP15 were localized to cells within the kidney of the spiny dogfish, Squalus acanthias, using an immunohistochemical approach. Dogfish kidney has two zones, the bundle zone (including five nephron segment bundles) and the sinus zone (with two major loops). In order to discriminate between the two loops, the cilia occurring in the first proximal/intermediate loop were labeled with two antibodies including an anti-acetylated tubulin antibody. The second late distal tubule loop (LDT) was identified, as the nephron in that region has no luminal cilia. Strong staining of the rabbit anti-dogfish AQP3, AQP4 (AQP4/2) or AQP15 polyclonal antibodies localized to LDT tubules. These antibodies were further co-stained with a mouse anti-Na+,K+-ATPase a5 monoclonal antibody, as Na+,K+-ATPase has previously been suggested to localize to the early distal tubule (EDT) and LDT and a mouse anti-NKCC T4 antibody, as NKCC2 was previously suggested to be located in the EDT and the second half of the LDT. In the LDT, strong AQP4/2 and AQP15 antibody staining localized together with the strong Na+,K+-ATPase antibody staining, whereas strong AQP3 antibody staining was largely separate but with an overlapping distribution. Very low levels of AQP4/2 antibody basal membrane staining was also detected in the first proximal /intermediate loop of the sinus zone. There was no mouse anti-NKCC T4 antibody staining apparent in the LDT. In the convoluted part of the bundle zone, the AQP4/2 and Na+,K+-ATPase but not the AQP3 or AQP15 antibodies stained tubule segments, with both AQP4/2 and Na+,K+-ATPase staining the EDT, and with low-level AQP4/2 staining of two other tubules of the bundle, which were most likely to be the proximal 1a (PIa) and intermediate II (IS II) tubules. The AQP4/2 antibody also stained the EDT in the straight bundle zone. The mouse anti-NKCC T4 antibody stained the apical region of EDT tubules in the convoluted bundle zone, suggesting that the antibody was binding to the NKCC2 cotransporter. The AQP15 antibody appeared to bind to the peritubular sheath surrounding bundles in the bundle zone. Due to the AQP4/2 antibody staining in the EDT that immediately proceeds and continues into the LDT, this suggested that the strong AQP4/2, AQP15 and Na+,K+-ATPase antibody staining was located at the beginning of the LDT and therefore the strong AQP3 was located at the end of the LDT. The staining of all three AQP antibodies was blocked by the peptide-antigen used to make each one, suggesting that all the staining is specific to each antibody.

Delayed complication due to retained contrast following augmented pressure distal loop colostogram in anorectal malformation

Augmented-pressure distal loop colostogram (APDC) is the most important diagnostic investigation to delineate the detailed anatomy to plan the reparative management of anorectal malformations. APDC is generally considered safe, with a very low complication rate. Herein, we present an unreported complication of APDC, manifesting as acute abdomen, due to retained contrast in distal loop. The patient was managed with evacuation of retained contrast from distal loop. We recommend evacuating the contrast from the distal loop following APDC.

Outcome of Tapering Enteroplasty in Managing Jejunoileal Atresia.

Jejunoileal atresia (JIA) represents a common cause of neonatal bowel obstruction. There is a discrepancy between the diameters of the proximal and the distal bowel loops and this is managed with excision or tapering of the dilated proximal bowel loop. We aim primarily to evaluate the outcome of tapering enteroplasty (TE) in managing JIA and secondarily to compare the outcome of TE to non-TE. A retrospective analysis of records of all neonatal admissions with JIA from January 2017 to December 2018 at a tertiary university children's hospital. Type and location of atresia, time to full enteral feeds, length of stay (LOS), complications, and outcome were assessed in TE and non-TE groups. Forty-one patients were included in the study; 29 (70.7%) cases had jejunal atresia and 12 (29.3%) had ileal atresia. Seventeen (41.4%) patients had TE. The median days to full feeds was 19; 28 in the TE group versus 16 in the non-TE group (P = 0.022). Four (9.7%) cases needed a re-exploration because of failure to start feeds; all in the non-TE group. The median LOS was 33 days for TE versus 22 days for non-TE (P = 0.101). Twenty-one cases (51.2%) developed a wound infection and showed a significantly longer median LOS of 29.5 versus 19 days (P = 0.019). Mortality was 7 (17.1%). TE did not show a superior outcome when compared to resection of the dilated bowel. It was associated with longer time to reach full enteral nutrition and longer LOS.