Small Loops Research Articles (Page 1)

When Surgery meets Autoimmunity: A Case of Pneumatosis Cystoides Intestinalis mimicking mesenteric infarct in systemic sclerosis

Accurately modeling nucleic acid structure and dynamics remains challenging for all-atom simulations, especially for noncanonical motifs such as small loops and G-quadruplexes. Despite these advances, current all-atom classical force fields often fail to reproduce ensembles consistent with high-resolution experimental data. We present a systematic refinement strategy for AMBER-based force fields that incorporates nuclear Overhauser effect distance data from NMR experiments within an ensemble-averaged optimization framework. By selectively tuning van der Waals interaction pairs, this approach markedly reduces simulation-experiment discrepancies, removes persistent artifacts, and generates free energy landscapes that better reflect experimental observations. We demonstrate broad applicability across diverse DNA and RNA systems including flexible loops and G-quadruplexes. Overall, this transferable strategy significantly improves structural accuracy and predictive power, enabling more reliable modeling of complex nucleic acid conformational ensembles.

High-throughput analysis of dislocation loops in irradiated metals using Mask R-CNN.

Background: Abdominal trauma is a frequent cause of pediatric emergency admissions, but traumatic evisceration is exceptionally rare. It is defined as the protrusion of intra-abdominal organs through a defect in the abdominal wall. In children, the elasticity of the abdominal wall usually provides protection, which explains the rarity of this presentation. Case presentation: We report the case of an 11-year-old boy with no significant past medical history who sustained a road traffic accident with violent crushing trauma. On admission, clinical examination revealed a 10 cm abdominal wall laceration extending from the left iliac fossa to the hypogastrium, with evisceration of viable sigmoid colon and several small bowel loops. Multiple superficial abrasions were also noted on the trunk. The patient was hemodynamically stabilized after initial resuscitation. Emergency laparotomy confirmed the absence of intestinal perforation or associated intra-abdominal lesions. The surgical procedure included reduction of the eviscerated bowel, abundant peritoneal lavage, and placement of a drain. Broad-spectrum antibiotics were administered. The postoperative course was uneventful, with bowel function recovery on postoperative day 2 and hospital discharge on day 7. At one-month follow-up, the patient was asymptomatic with satisfactory wound healing. Conclusion: Post-traumatic evisceration in children is an exceptional but severe surgical emergency. Its management requires prompt resuscitation, early laparotomy, and careful abdominal wall repair. Long-term follow-up is necessary to assess both functional and cosmetic outcomes.

Chilaiditi Syndrome Caused by Fitz-Hugh-Curtis: Ultrasound and Computed Tomography Findings.

ABSTRACTObturator hernia is a rare internal hernia causing significant mortality and morbidity in elderly age groups. Diagnosis of obturator hernia is challenging because of vague atypical presentations. This case report describes a woman in her late 80s who presented with colicky right lower abdominal pain, abdominal distension, and obstipation, diagnosed with a right obturator hernia, computed tomography (CT) scan. An elderly female presented with chief complaints of right lower abdominal pain and abdominal distension. On examination, the abdomen was distended with generalized tenderness and rebound tenderness. CECT abdomen and pelvis showed dilated small bowel loops with a transition point caused by herniation through the right obturator foramen. Emergency laparotomy revealed a right strangulated obturator hernia. Resection of the gangrenous ileal segment with ileo‐ileal anastomosis and primary closure of the defect was done. Obturator hernia occurs through the obturator canal, which is mostly seen in elderly females. Obturator hernia usually presents as partial bowel obstruction because of a high frequency (41%–100%) of Richter's herniation of the small bowel into the obturator canal. Diagnosis can be delayed because of its nonspecific clinical presentation. CT scan is the most accurate and sensitive way to diagnose the obturator hernia. Obturator defects can be repaired by various methods including simple suture closure, closure of the obturator with adjacent tissue, and mesh placement during laparotomy. Obturator hernia is a rare abdominal hernia with delayed diagnosis because of vague atypical clinical presentation. Early diagnosis and prompt surgical treatment are essential to reduce morbidity and mortality.

Herniation, rotation, looping, and retraction of the midgut occur sequentially during midgut morphogenesis. Recent studies have demonstrated the importance of mechanical forces arising from the differential growth between the midgut and mesentery in the formation of small intestinal loops. However, the roles of mechanics and differential growth in the overall process remain unclear. In this study, we developed a computational model of midgut morphogenesis based on continuum mechanics. We showed that the protrusion, rotation, and retraction of the midgut can emerge sequentially because of temporal changes in differential growth. The midgut was modeled as a hyperelastic tube with a Gaussian shape. The differential growth of the midgut and mesentery was modeled by the spatial variation in spontaneous plastic deformation. The hyperelastic tube developed a protrusion by compression-induced deformation, suggesting that other external forces are not necessary for midgut herniation prior to rotation. Appropriate differential growth induced a rotation of the tube. A less-growing mesentery attempts to face inward to minimize the tensile forces, which causes tube twisting and results in midgut rotation. Excess differential growth may cause the retraction of the midgut before the formation of small intestinal loops. The results of this study will serve as reference in future studies on embryology and tissue engineering.

SELEX identifies high-affinity RNA targets for chromatin-binding proteins PARP1 and MeCP2

Abstract Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) are routinely performed in patients with Crohn’s disease and allow panoramic view of the abdominal region, permitting to identify intestinal disease, extra-intestinal manifestations and vascular alteration surrounding the bowel wall. Considering that most errors are related to an insufficient distension of the bowel, the requisite for an adequate MRI or CT study of the intestine is the correct bowel distension in order to have the visualization of the entire bowel. For these reasons, CT and MRI are performed after administration of a contrast medium by mouth (MR-enterography; CT-enterography) or by naso-jenunal tube (MR-enteroclysis; CT-enteroclysis). The method of administration of the contrast medium affects the degree of distension of the intestinal loops. In particular, not all small bowel loops are equally distended after administration of the contrast agents by mouth, being ileum usually better distended than jejunum. This problem could be solved by using MR enteroclysis and CT-enteroclysis. In these techniques, contrast medium is administered through naso-jejunal tube, and a better small bowel distension is usually obtained. Even if the study of small bowel disease is the most common indication of MR-enterography or MR-enteroclysis and CT-enterography or CT-enteroclysis, these techniques occasionally may be focused on colon examination. Additionally, water enema may be performed at the end of the MR-enterography (Hydro-MRI) to reach optimal colon-rectum distension. In this paper the Authors review the techniques of intestinal distension described in literature, using some CT and MR examples.

A 36-year-old female was evaluated for pelvic pain of 6 months duration. She presented to our clinic with the MRI report suggestive of a well-de ned, solid, T1 heterogeneously hypointense and T2 heterogeneously hyperintense lesion displaying post-contrast enhancement, central non-enhancing cystic areas, and areas displaying diffusion restriction, measuring 5.1 x 5.0 x 5.7 cm (APXTRXCC), noted in the mid pelvis at the level of the L5 vertebral body and the L5-S1 intervertebral disc. (Fig 1.). Black arrow pointing to the tumor. The lesion was noted closely abutting the bilateral iliac vessels posterolaterally. Anteriorly the lesion was noted abutting small bowel loops. Functional paraganglioma was ruled out by testing plasma-free metanephrines and 24-hour urine vanillylmandelic acid levels.

A 62-year-old female presented to the Emergency Department of the General Hospital of Katerini, Greece, complaining of abdominal pain, fever, and general discomfort. Laboratory tests indicated an elevated white blood cell count and an elevated C-reactive protein level. A computed tomography (CT) scan revealed dilated small bowel loops and free intraperitoneal fluid. During laparotomy, extensive ischemia and necrosis of both the small and large bowel were discovered, and a resection of the small bowel and the right colon was performed, leaving the patient with only 90 cm of small intestine and a jejunocolic anastomosis. Postoperative management was particularly challenging, requiring a multidisciplinary approach, an intensive care unit stay, reoperations due to anastomotic leaks, continuous parenteral nutrition and electrolyte management, and aggressive antibiotic treatment for persistent bacterial infections. This case report highlights the importance of appropriate management of this life-threatening complication following extensive bowel resection.

Foreign body ingestion is common problem in the paediatric population with 80% cases occurring in children under three years old. We reported a case of acute intestinal obstruction secondary to water bead ingestion. A 1-year-9-month-old boy presented with low-grade fever, non-projectile vomiting and severe acute abdomen for a day. The abdomen was distended and tense with generalised tenderness and guarding. There was neither witness of foreign body ingestion nor radio-opaque foreign body seen on the plain abdominal radiography but only presence of dilated small bowels. Ultrasound abdomen revealed grossly dilated fluid-filled small bowel loops with minimal interloop-free fluid. He underwent laparotomy in which a water bead size 4 cm was found 71cm from distal jejunum. Enterotomy with foreign body removal and primary repair was performed. Water beads are made of super absorbent polymer which can grow 100 times their original size when exposed to water. They are often used as home decorative items. Due to their attractive appearance – bright-coloured, crystal ball-like or even resembling candies, they can be easily mistaken by young children as food item and ingested by them. These beads are radiolucent on plain radiographs, frequently leading to delayed diagnosis and treatment. Water bead ingestion is a new and emerging unexpected cause of intestinal obstruction. This may result in choking, internal injuries and even death if left undetected. These objects must be stored out of reach of children. Increasing awareness among the public and medical personnel about home accidents caused by water bead ingestion is essential to prevent similar incidents.

Rationale:Hiatal hernia is one of the rarest types of internal herniation that can occur after gastrectomy. We present a case of hiatal hernia accompanied with afferent loop syndrome.Patient concerns:An 82-year-old male, who had undergone laparoscopic total gastrectomy and D2 lymphadenectomy with Roux-en-Y reconstruction 10 months prior was admitted to the emergency room with acute abdominal pain.Diagnoses:A computed tomography revealed a hiatal hernia containing efferent and left-sided small bowel loops, dilation of the afferent limb, and dilation of the extrahepatic biliary duct due to afferent limb obstruction.Interventions:Laparoscopic reduction was significantly hindered by bowel edema. To ease the reduction of the small bowel, an incision was made to the diaphragm to ensure a bigger hiatal opening. After the reduction was complete, the hiatal opening was sutured to reduce the size of the diaphragmatic hiatus.Outcomes:Reduced small bowels were in viable condition. The patient was discharged eleven days after surgery without any complications.Lessons:The case demonstrates that hiatal hernia with afferent loop syndrome can occur after total gastrectomy with Roux-en-Y reconstruction. And, in such cases, incision of the diaphragm may be necessary for a safer bowel reduction.

Context. Plages are small concentrations of strong, nearly vertical magnetic fields in the solar photosphere that expand with height. A high spatial and spectral resolution that can resolve their fine structure is required to characterize them, and spectropolarimetric capabilities are needed to infer their magnetic fields. Aims. We constrain the 3D fine structure of the magnetic field in the photosphere of a solar plage from a unique spectropolarimetric dataset with a very high spatial and spectral resolution and a fast temporal cadence. Methods. We analyzed spectropolarimetric observations of a solar plage in the two magnetically sensitive spectral lines of neutral iron around 630 nm. The observations were obtained with MiHI, which is an integral field unit attached to the Swedish Solar Telescope. MiHI obtained diffraction-limited, high-cadence observations with high spectral fidelity. These observations were interpreted using the spectropolarimetric inversion with magnetohydrostatic constraints, which allowed us to recover the magnetic and thermodynamic structure of the plage on a geometrical scale. Results. The inversion results reveal that the magnetic field can reach up to 2 kG and that it expands significantly from the deep to the mid-photosphere. Weaker (≈200 G), and very small (subarcsecond) vertical magnetic loops lie beneath this canopy, rooted in the photosphere. Conclusions. This novel picture of a solar plage, in which weak opposite-polarity field patches surround the main polarity, provides new insight into convection in strongly magnetized plasma.

Chronic active Epstein-Barr virus (CAEBV) can induce complications in various organs, including the brain and gastrointestinal tract. A 3-year-old boy was referred to the hospital with a history of fever and seizures for 15 days. A diagnosis of encephalitis based on computed tomography (CT) and magnetic resonance imaging findings and clinical correlation was made. Laboratory tests showed positive serology for Epstein-Barr virus (EBV) and negative for Rotavirus antigen and IgG and IgM antibodies for cytomegalovirus, herpes simplex virus, and varicella zoster virus, respectively. Abdominal CT showed diffuse wall thickening with fluid distension of small bowel loops, lower abdomen wall thickening, and a small amount of ascites. The biopsy demonstrated positive Epstein-Barr encoding region in situ hybridization in cells within the crypts and lamina propria. The patient was managed with steroids and hematopoietic stem cell transplantation (HSCT). This case showed histopathological characteristics of concurrent EBV-associated encephalitis and colitis in CAEBV infection. The three-step strategy of immunosuppressive therapy, chemotherapy, and allogeneic HSCT should be always be considered for prevention of disease progression.

Abstract Recent high-resolution solar observations have unveiled the presence of small-scale loop-like structures in the lower solar atmosphere, often referred to as unresolved fine structures, low-lying loops, and miniature hot loops. These structures undergo rapid changes within minutes, and their formation mechanism has remained elusive. In this study, we conducted a comprehensive analysis of two small loops utilizing data from the Interface Region Imaging Spectrograph (IRIS), the Goode Solar Telescope (GST) at Big Bear Solar Observatory, and the Atmospheric Imaging Assembly and the Helioseismic Magnetic Imager on board the Solar Dynamics Observatory, aiming to elucidate the underlying process behind their formation. The GST observations revealed that these loops, with lengths of ∼3.5 Mm and heights of ∼1 Mm, manifest as bright emission structures in Hα wing images, particularly prominent in the red wing. IRIS observations showcased these loops in 1330 Å slit-jaw images, with transition region (TR) and chromospheric line spectra exhibiting significant enhancement and broadening above the loops, indicative of plasmoid-mediated reconnection during their formation. Additionally, we observed upward-erupting jets above these loops across various passbands. Furthermore, differential emission measurement analysis reveals an enhanced emission measure at the location of these loops, suggesting the presence of plasma exceeding 1 MK. Based on our observations, we propose that these loops and associated jets align with the minifilament eruption model. Our findings suggest a unified mechanism governing the formation of small-scale loops and jets akin to larger-scale X-ray jets.

COVID-19 infection presents with a range of clinical manifestations, from pulmonary symptoms to multisystem organ involvement. Gastrointestinal complications, while commonly reported in adults and critically ill individuals, are not frequently seen in the pediatric population. This case report discusses a 4-year-old boy who developed abdominal distension during the course of an acute COVID-19 infection. Radiological findings were consistent with paralytic ileus. The child had a history of end-stage renal disease secondary to steroid-resistant nephrotic syndrome and had undergone a living kidney transplant eight months prior. He presented with fever, upper respiratory tract symptoms, abdominal pain, and vomiting. Despite not appearing clinically ill, his abdomen was significantly distended. An abdominal X-ray revealed dilated small bowel loops and multiple air-fluid levels. He was managed conservatively as a case of paralytic ileus. This report suggests a possible association between COVID-19 infection and the development of paralytic ileus in non-critically ill patients. We emphasize the importance of anticipating gastrointestinal complications in clinically stable patients with COVID-19 infection.

C. perfringens type F isolates are a leading cause of food poisoning and antibiotic-associated diarrhea. Type F isolate virulence requires production of C. perfringens enterotoxin [CPE], which acts by forming large pore complexes in host cell plasma membranes. During GI disease, CPE is produced in the intestines when type F strains undergo sporulation. The toxin is then released into the intestinal lumen when the mother cell lyses at the completion of sporulation. Once present in the lumen, CPE encounters proteases. This study examined the in vitro, ex vivo, and in vivo processing of CPE by intestinal proteases and the effects of this processing on CPE activity. Results using purified trypsin or mouse intestinal contents detected the rapid cleavage of CPE to a major band of ~32 kDa and studies with Caco-2 cells showed that this processed CPE still forms large complexes and retains cytotoxic activity. When mouse small intestinal loops were challenged with CPE, the toxin caused intestinal histologic damage, despite rapid proteolytic processing of most CPE to 32 kDa within 15 min. Intestinal large CPE complexes became more stable with longer treatment times. These results indicate that CPE processing involving trypsin occurs in the intestines and the processed toxin retains enterotoxicity.

Abstract Introduction Bowel obstruction following Roux-en-Y gastric bypass (RYGB) is observed in 1.5% to 11% of patients, with small bowel obstruction (SBO) compromising only 1.8% of these cases. SBO is categorized by time of onset as either early, within 30 days post-surgery, or late. Early obstruction typically involves surgical technical errors or dietary noncompliance. Phytobezoars, such as the one observed in our case, account for less than 1% of SBOs post-RYGB. Zopiclone, a nonbenzodiazepine hypnotic, has a maximum recommended dosage of 7.5 mg daily. Anterograde amnesia is a rare side effect of zopiclone, particularly at higher doses. Although the patient did not initially report zopiclone use, a psychiatric evaluation following the complication revealed frequent self-medication with this hypnotic. This case report is unique because phytobezoar-induced SBOs are rare and generally manifest months or years after the initial surgery. However, in our case, the obstruction occurred within the first 48 postoperative hours, in a technically correct surgery, and under unexpected circumstances. Case Presentation A laparoscopic revisional Roux-en-Y gastric bypass was successfully performed on a 59-year-old woman. The patient was discharged 24 hours after the procedure with detailed medical and nutritional instructions. However, she was readmitted 24 hours later due to acute epigastric pain and multiple episodes of vomiting. She denied any dietary indiscretions or taking non-prescribed medications. On physical examination, the patient had abdominal distension and epigastric tenderness, without signs of peritonitis. Blood analysis revealed leukocytosis with neutrophilia. A contrast CT scan showed dilated small bowel loops, right pleural effusion, and some free gas in the mediastinum. An emergency diagnostic laparoscopy revealed a normal gastric pouch and preserved anastomoses, along with dilated small bowel loops. The jejunojejunal anastomosis was disassembled, revealing undigested solid food content, including seeds, causing intestinal obstruction. The organic material was removed, and the anastomosis was reconstructed. Additionally, mesenteric gaps were closed, abdominal lavage was performed, and a left subphrenic drain was inserted. Postoperatively, the patient developed oliguria and was diagnosed with abdominal sepsis and Acute Kidney Injury (AKIN) II by the critical care team. Antibiotic and diuretic therapies were adjusted, and parenteral nutrition was started. A psychiatric consultation revealed the patient had been self-medicating with zopiclone at four times the recommended dose (30 mg each night). This had caused an anterograde amnesic episode due to the overmedication, resulting in her inability to remember her alimentary transgression. The patient was hospitalized for 10 days, during which she overcame her sepsis and achieved oral tolerance. Psychiatric, medical, and nutritional follow-up were arranged for her thereafter. Conclusion This case underscores the critical importance of obtaining a comprehensive medical history during initial patient evaluation. Patients must be informed of the necessity of disclosing all medications, including over the counter and self-prescribed drugs. In this instance, zopiclone-induced anterograde amnesia was identified as the precipitating factor for intestinal obstruction. Early identification of medication misuse is essential to prevent such complications and to ensure optimal patient outcomes.

Here, we sought to determine the role of specific RNA structural motifs in the interaction of RNA with model lipid vesicles containing liquid-ordered domains (RAFT liposomes). We show that the presence of several small apical loops within RNA structure favors RNA affinity for RAFT liposomes while the increased number of nucleotides within bulges inhibits this affinity. FRET flow cytometry measurements confirmed a modulation of the interaction of RNA with plasma membrane by the presence of specific RNA structural motifs. The analysis of viral RNA fragments revealed that a long double helix at the apical loop increases the affinity of viral RNA to lipid rafts. The analysis of exosomal Y RNAs secreted by nematode parasites showed that the presence of the EXO-motif GGAG is strongly correlated to the presence of small number of large apical loops within RNA structure. These results show that RNA structural motifs can modulate RNA affinity to liquid-ordered membrane lipid raft domains thus suggesting the importance of these motifs both for the mechanism of RNA loading into extracellular vesicles, and for the development of RNA-based lipid biosensors for monitoring of viral RNAs in biofluids and wastewater.