More Than Just a Spearhead: Diverse Functions of PAAR for Assembly and Delivery of Toxins of the Contractile Injection Systems

The type VI secretion system (T6SS) belongs to the evolutionarily related group of contractile injection systems that employ a contractile outer sheath to inject a rigid spear-like inner tube into target bacterial and eukaryotic cells. The tip of the rigid tube is often decorated by a PAAR-repeat protein as a key structural component.

Clinical and imaging interrelationships in the diagnosis of foreign body aspiration in children

Background: Foreign body aspiration (FBA) is a typical occurrence in children. The clinical signs are influenced by various causes, and the differential diagnosis is important, especially when the suffocation crisis is not recognized. The aim of this study was to evaluate the clinical and imaging symptoms in children with FBA. Material and methods: A retrospective study is provided of 156 children who were hospitalized and examined (clinical and paraclinical tests) in the Pneumology Clinic between 2011 and 2020 after having a foreign body removed from their airways, using rigid tube bronchoscopy or fibrobronchoscopy. Results: The most affected age group was 1-3 years, which constituted 77.6% (95% CI 70.2% -83.8%). The most common symptoms were: cough – 98.7% (95% CI 95.4%-99.8%), dyspnoea – 94.2% (95% CI 89.3%-97.3%), wheezing – 61.5% (95% CI 53.4%-69.2%). Chest radiography was relevant for foreign body aspirations in 55.8% of cases (95% CI 47.6%-63.7%). The foreign body was extracted from the right bronchus in 32.1%, from the left bronchus in 21.8% of cases, from the lobar / segmental bronchi – 22.5%, and in 21.2% – multiple locations. The etiological structure of the endobronchial foreign body was dominated by the organic ones – 96.8%. Conclusions: Cough, dyspnoea, and wheezing are suggestive of this pediatric emergency. Chest radiography provides diagnostic information only for every second child.

On Green’s function for Laplace’s equation in a rigid tube

A classical problem from potential theory (a point source inside a long rigid tube) is revisited. It has an extensive literature but its resolution is not straightforward: standard approaches lead to divergent integrals or require the discarding of infinite constants. We show that the problem can be solved rigorously using classical methods.

O27 The diameter of an anorectal physiology catheter in the anal canal influences the results

Introduction Conventional “catheter-based” anorectal physiology systems may influence anal canal pressures by stretching the sphincters thereby increasing tension. Anal acoustic reflectometry (AAR) is a “catheter-less” technique as the flexible thin catheter does not distort the anal canal. The aim of this study was to explore whether the size of rigid tube in the anal canal had any effect on tension. Method Participants with no anorectal dysfunction were included. Baseline resting/squeeze AAR measurements were recorded, then repeated with a 6 mm and 10 mm rigid tube placed along-side the AAR catheter. This process was repeated for anorectal manometry (ARM) and Opening pressure (AAR) and mean resting pressure (MRP) were used to calculate tension (pressure (mmHg) x radius (mm)). Result 9 participants were included (7 female/2male) with median age 22 years (21–31 years). Tension at rest (no additional tube) for AAR and ARM was 14 and 135 N/m respectively and 33 and 238 N/m during squeeze. Tension increased in a linear fashion, for both resting and squeeze, as the size of additional rigid tube increased. The largest increase in tension from baseline AAR and ARM measurements was recorded with the 10 mm additional tube (1,807% and 102% respectively). Conclusion The thin AAR catheter exerted the lowest tension at baseline. A large increase in tension was observed as the size of tube increased and therefore the diameter of catheter used in the assessment of anal physiology will affect the results. ARM measurements carried out by devices of different diameter will not be comparable. Take-home Message The diameter of the anorectal physiology catheter in the anal canal influences the results.

Soft but Not Too Soft—How a Rigid Tube Expands without Breaking

Fungi grow by apical extension of their hyphae. The continuous growth requires constant delivery of vesicles, which fuse with the membrane and secrete cell wall biosynthesis enzymes.

Quantitative description of a contractile macromolecular machine

Contractile injection systems (CISs) [type VI secretion system (T6SS), phage tails, and tailocins] use a contractile sheath-rigid tube machinery to breach cell walls and lipid membranes. The structures of the pre- and postcontraction states of several CISs are known, but the mechanism of contraction remains poorly understood. Combining structural information of the end states of the 12-megadalton R-type pyocin sheath-tube complex with thermodynamic and force spectroscopy analyses and an original modeling procedure, we describe the mechanism of pyocin contraction. We show that this nanomachine has an activation energy of 160 kilocalories/mole (kcal/mol), and it releases 2160 kcal/mol of heat and develops a force greater than 500 piconewtons. Our combined approach provides a quantitative and experimental description of the membrane penetration process by a CIS.

Linitis Plastica of Terminal Ileum

Linitis plastica generally involves stomach. Most common cause is diffuse signet ring adenocarcinoma, metastatic disease from breast and lungs can also lead to Linitis plastica and also caustic burns. In Linitis plastica the stomach becomes rigid and pipe like (leather bottle). We are presenting a rare case of Linitis plastica of terminal ileum. Ours is a 55-year female patient presenting in casualty with abdominal pain, distension, vomiting and bilious vomiting. Her terminal ileum had stricturous rigid tube-like lesion with multiple mesenteric lymphadenitis. We did curative resection (ileoascending colon) and anastomosis. She had uneventful recovery. Though small bowel malignancies are rare, one should have high index of suspicion when one encounters rigid pipe like strictures lesion of ileum, as these can be malignant lesion and one should perform curative resection. Surgery improves survival rate along with adjuvant chemotherapy as required. Key words: Linitis plastica, small bowel malignancy, Linitis plastica ileum, Linitis plastica stomach.

Extended Depth-of-Field of a Miniature Optical Endoscope Using Wavefront Coding

Endoscopic imaging is an indispensable tool for visual inspection of surfaces in hard-to-access places. The conventional optical endoscope only enables imaging the regions that lie close to the focal plane, and therefore improving the depth of field (DOF) of an endoscopic system has recently attracted much attention. Here, we propose and demonstrate a simple, cost-effective, and easily available industrial endoscopic system, which is composed of a rigid tube and group of optical lenses. The outer diameter of the designed endoscopic modality presented in this article is 3 mm. By employing the wavefront coding technique, the DOF of newly-designed endoscope was extended to 2.7 mm in the proof-of-concept experiment, which is an increase of almost 10 times compared to the initial counterpart.