Exploring the Landscape of Aptamers: From Cross-Reactive to Selective to Specific, High-Affinity Receptors for Cocaine.

We reported over 20 years ago MNS-4.1, the first DNA aptamer with a micromolar affinity for cocaine. MNS-4.1 is based on a structural motif that is very common in any random pool of oligonucleotides, and it is actually a nonspecific hydrophobic receptor with wide cross-reactivity with alkaloids and steroids. Despite such weaknesses preventing broad applications, this aptamer became widely used in proof-of-concept demonstrations of new formats of biosensors. We now report a series of progressively improved DNA aptamers recognizing cocaine, with the final optimized receptors having low nanomolar affinity and over a thousand-fold selectivity over the initial cross-reactants. In the process of optimization, we tested different methods to eliminate cross-reactivities and improve affinity, eventually achieving properties that are comparable to those of the reported monoclonal antibody candidates for the therapy of overdose. Multiple aptamers that we now report share structural motifs with the previously reported receptor for serotonin. Further mutagenesis studies revealed a palindromic, highly adaptable, broadly cross-reactive hydrophobic motif that could be rebuilt through mutagenesis, expansion of linker regions, and selections into receptors with exceptional affinities and varying specificities.

Faecal Immunochemical Testing to Detect Colorectal Cancer in Symptomatic Patients: A Diagnostic Accuracy Study.

(1) Background: NHS England recommended faecal immunochemical testing (FIT) for symptomatic patients in June 2020 to rationalise limited diagnostic services during COVID-19. (2) Aim: to investigate the diagnostic performance of FIT, analysing the proportion of FIT-negative colorectal cancers (CRC) missed in symptomatic patients and how this risk could be mitigated. (3) Design and Setting: a retrospective study of biochemistry and cancer databases involving patients referred from primary healthcare with suspected CRC to a single secondary care trust in North East London. (4) Methods: a retrospective cohort diagnostic accuracy study was undertaken to determine the performance of FIT for detecting CRC at 10 µgHb/g. (5) Results: between January and December 2020, 7653 patients provided a stool sample for FIT analysis; 1679 (22%) samples were excluded due to inadequate or incorrect specimens; 48% of suspected CRC referrals completed FIT before evaluation; 86 FIT tested patients were diagnosed with histologically proven CRC. At 10 µgHb/g, FIT performance was comparable with the existing literature with a sensitivity of 0.8140 (95% CI 0.7189-0.8821), a specificity of 0.7704 (95% CI 0.7595-0.7809), a positive predictive value (PPV) of 0.04923 (95% CI 0.03915-0.06174), a negative predictive value (NPV) of 0.9965 (95% CI 0.9943-0.9978), and a likelihood ratio (LR) of 3.545; 16 patients with CRC had an FIT of ≤10 µgHb/g (18.6% 95% CI 11.0-28.4%). (6) Conclusions: this study raises concerns about compliance with FIT testing and the incidence of FIT-negative CRC at the NICE recommended threshold and how this risk can be mitigated without colonic imaging. Whilst FIT may have facilitated prioritisation during COVID-19, we must be cautious about using FIT alone to determine which patients are referred to secondary care or receive further investigation.

A functional group-guided approach to aptamers for small molecules.

Aptameric receptors are important biosensor components, yet our ability to identify them depends on the target structures. We analyzed the contributions of individual functional groups on small molecules to binding within 27 target-aptamer pairs, identifying potential hindrances to receptor isolation-for example, negative cooperativity between sterically hindered functional groups. To increase the probability of aptamer isolation for important targets, such as leucine and voriconazole, for which multiple previous selection attempts failed, we designed tailored strategies focused on overcoming individual structural barriers to successful selections. This approach enables us to move beyond standardized protocols into functional group-guided searches, relying on sequences common to receptors for targets and their analogs to serve as anchors in regions of vast oligonucleotide spaces wherein useful reagents are likely to be found.

Is Panenteric PillcamTM Crohn's Capsule Endoscopy Ready for Widespread Use? A Narrative Review.

Patients diagnosed with Crohn's disease are increasingly subjected to repeat colonoscopic and radiological examinations to assess the extent of the disease severity and the effects of treatment. PillcamTM Crohn's video capsule, a modified colon capsule, was developed to generate a minimally invasive mouth to rectum video of the gastrointestinal tract. The capsule provides a wide-angle panoramic mucosal view to assess inflammation, ulceration, stenosis, disease extent, and effect of treatment. This review summarizes the evidence of its utility in both adult and paediatric Crohn's disease and reviews the scoring systems used to quantify findings. The literature survey indicates that the PillcamTM Crohn's capsule offers high sensitivity and specificity for the detection of inflammatory lesions and the extent and distribution of disease, and it could be considered a reliable imaging modality in both adults and childhood with Crohn's disease.

A cohort study of duplicate faecal immunochemical testing in patients at risk of colorectal cancer from North-West England.

OBJECTIVES: We sought to investigate if duplicate faecal immunochemical testing (FIT) sampling improves the negative and positive predictive value of patients thought to be at risk of colorectal cancer (CRC). Specifically, we aimed to investigate whether the proportion of FIT-negative CRC missed by a single FIT test in symptomatic patients could be reduced by duplicate FIT testing. DESIGN: A retrospective service evaluation cohort study of the diagnostic accuracy of duplicate FIT testing. SETTING: Patients referred from primary care with suspected CRC to four secondary care trusts in North-West England. PARTICIPANTS: 28 622 patients over 18-years-old with lower gastrointestinal symptoms suggestive of CRC who completed two FIT samples. PRIMARY AND SECONDARY OUTCOME MEASURES: The performance of duplicate FIT for detecting CRC at a threshold of 10 µgHb/g. RESULTS: The sensitivity if either test was >10 µgHb/g was 0.978 (0.955-0.989), specificity was 0.662 (0.657-0.668), positive predictive value 0.031 (0.028-0.035) and negative predictive value 1.00 (0.999-1.00). Despite two-thirds of patients (18952) being negative following two tests, at this threshold only seven CRC were missed over a 26-month period. All seven patients had other high-risk features which should have prompted investigation. CONCLUSIONS: This study suggests that in routine NHS practice, a duplicate FIT sample strategy together with clinical evaluation for evidence of anaemia and weight loss is superior to a single FIT sample alone and would allow symptomatic patients to be managed in primary care without the need for urgent referral to secondary care for urgent colonic imaging.

Review: Colon Capsule Endoscopy in Inflammatory Bowel Disease.

The COVID-19 pandemic has caused considerable disruption in healthcare services and has had a substantial impact on the care of patients with chronic diseases, such as inflammatory bowel disease. Endoscopy services were significantly restricted, resulting in long waiting lists. There has been a growing interest in the use of capsule endoscopy in the diagnostic pathway and management of these patients. This review explores the published literature on the role of colon capsule endoscopy in ulcerative colitis and Crohn's disease as a method for mucosal assessment of extent, severity, and response to treatment. Colon capsule preparation regimens and scoring systems are reported. The studies indicate that, despite inherent limitations of minimally invasive capsule endoscopy, there is increasing evidence to support the use of the second-generation colon capsule in inflammatory bowel disease evaluation, providing an additional pathway to expedite investigation of appropriate patients especially during and after the pandemic.

QbD-driven formulation development and evaluation of topical hydrogel containing ketoconazole loaded cubosomes.

The proposed study aimed to develop topical hydrogel containing ketoconazole loaded cubosomes with lower surfactant concentrations using the 'Quality by Design' (QbD) approach. Risk assessment was performed, followed by screening and optimization of formulations by 32 factorial design using Design-Expert® software. Keeping the combination of constituents similar to that of the optimized batches as predicted post conduct of 'Design of Experiment' (DoE) studies, scale-up batches were prepared. The 32 factorial design model successfully predicted the composition of the optimized formulation within the confidence limits. In vitro drug release study was performed and analyzed by various mathematical models. Ex vivo permeation study was investigated using goat ear skin. These ketoconazole loaded cubosomes showed a release pattern similar to the Korsmeyer-Peppas model experiencing Fickian diffusion having 67% cumulative ketoconazole release within 24 h. Ex vivo permeation study of hydrogel containing ketoconazole loaded cubosomes revealed a sustained release pattern through the goat ear skin with around 92.73 % release within 24 h. Scale-up studies also gave the confirmatory results for the post characterization studies, whereby the particle size of ketoconazole loaded cubosomes was 198 nm with 45% ketoconazole entrapment efficiency. This hydrogel containing ketoconazole loaded cubosomes can be used for topical drug delivery.

Optimizing Nutrition in Preterm Low Birth Weight Infants-Consensus Summary.

Preterm birth survivors are at a higher risk of growth and developmental disabilities compared to their term counterparts. Development of strategies to lower the complications of preterm birth forms the rising need of the hour. Appropriate nutrition is essential for the growth and development of preterm infants. Early administration of optimal nutrition to preterm birth survivors lowers the risk of adverse health outcomes and improves cognition in adulthood. A group of neonatologists, pediatricians, and nutrition experts convened to discuss and frame evidence-based recommendations for optimizing nutrition in preterm low birth weight (LBW) infants. The following were the primary recommendations of the panel: (1) enteral feeding is safe and may be preferred to parenteral nutrition due to the complications associated with the latter; however, parenteral nutrition may be a useful adjunct to enteral feeding in some critical cases; (2) early, fast, or continuous enteral feeding yields better outcomes compared to late, slow, or intermittent feeding, respectively; (3) routine use of nasogastric tubes is not advisable; (4) preterm infants can be fed while on ventilator or continuous positive airway pressure; (5) routine evaluation of gastric residuals and abdominal girth should be avoided; (6) expressed breast milk (EBM) is the first choice for feeding preterm infants due to its beneficial effects on cardiovascular, neurological, bone health, and growth outcomes; the second choice is donor pasteurized human milk; (7) EBM or donor milk may be fortified with human milk fortifiers, without increasing the osmolality of the milk, to meet the high protein requirements of preterm infants; (8) standard fortification is effective and safe but does not fulfill the high protein needs; (9) use of targeted and adjustable fortification, where possible, helps provide optimal nutrition; (10) optimizing weight gain in preterm infants prevents long-term cardiovascular complications; (11) checking for optimal weight and sucking/swallowing ability is essential prior to discharge of preterm infants; and (12) appropriate counseling and regular follow-up and monitoring after discharge will help achieve better long-term health outcomes. This consensus summary serves as a useful guide to clinicians in addressing the challenges and providing optimal nutrition to preterm LBW infants.

Cuboid Vesicles Formed by Frame-Guided Assembly on DNA Origami Scaffolds.

We describe the use of a frame-guided assembly (FGA) strategy to construct cuboid and dumbbell-shaped hetero-vesicles on DNA origami nanostructure scaffolds. These are achieved by varying the design of the DNA origami scaffolds that direct the distribution of the leading hydrophobic groups (LHG). By careful selection of LHGs, different types of amphiphiles (both polymer and small-molecule surfactants) were guided to form hetero-vesicles, demonstrating the versatility of the FGA strategy and its potential to construct asymmetric and dynamic hetero-vesicle assemblies with complex DNA nano-scaffolds.

DNA nanotechnology for nanophotonic applications.

DNA nanotechnology has touched the epitome of miniaturization by integrating various nanometer size particles with nanometer precision. This enticing bottom-up approach has employed small DNA tiles, large multi-dimensional polymeric structures or more recently DNA origami to organize nanoparticles of different inorganic materials, small organic molecules or macro-biomolecules like proteins, and RNAs into fascinating patterns that are difficult to achieve by other conventional methods. Here, we are especially interested in the self-assembly of nanomaterials that are potentially attractive elements in the burgeoning field of nanophotonics. These materials include plasmonic nanoparticles, quantum dots, fluorescent organic dyes, etc. DNA based self-assembly allows excellent control over distance, orientation and stoichiometry of these nano-elements that helps to engineer intelligent systems that can potentially pave the path for future technology. Many outstanding structures have been fabricated that are capable of fine tuning optical properties, such as fluorescence intensity and lifetime modulation, enhancement of Raman scattering and emergence of circular dichroism responses. Within the limited scope of this review we have tried to give a glimpse of the development of this still nascent but highly promising field to its current status as well as the existing challenges before us.

Gestational intestinal obstruction complicated by cortical blindness - a multidisciplinary case report.

Our case highlights the difficulty of diagnosing and managing surgical pathology during the advanced stages of pregnancy.

Transmural eosinophilic gastritis with gastric outlet obstruction: case report and review of the literature.

Eosinophil-associated gastrointestinal disorders (EGIDs) are uncommon conditions whose aetiologies are unclear, but which are characterised by eosinophilic infiltration and inflammation of the gastrointestinal tract in the absence of other causes of eosinophilia. We report the case of a 65-year-old woman with eosinophilic gastritis who underwent a Polya gastrectomy for a suspected gastric tumour with gastric outflow obstruction. Subsequent histological examination showed a non-malignant transmural eosinophilic infiltration of the stomach wall, a rare pathological entity. We present a review of the literature and discuss the management of such cases.

We still need to operate at night!

INTRODUCTION: In the past the National Confidential Enquiry into Peri-operative deaths (NCEPOD) have advocated a reduction in non-essential night-time operating in NHS hospitals. In this study a retrospective analysis of the emergency general surgical operative workload at a London Teaching centre was performed. METHODS: All general surgical and vascular emergency operations recorded prospectively on the theatre database between 1997 and 2004 were included in the study. Operations were categorised according to whether they commenced during the daytime(08:01-18:00 hours), evening(18:01-00:00 hours) or night-time(00:01-08:00 hours). The procedure type and grade of the participating surgical personnel were also recorded. Bivariate correlation was used to analyse changing trends in the emergency workload. RESULTS: In total 5,316 emergency operations were performed over the study period. The numbers of daytime, evening and night-time emergency procedures performed were 2,963(55.7%), 1,832(34.5%), and 521(9.8%) respectively. Laparotomies and complex vascular procedures collectively accounted for half of all cases performed after midnight whereas they represented only 30% of the combined daytime and evening emergency workload. Thirty-two percent (n = 166) of all night-time operations were supervised or performed by a consultant surgeon. The annual volume of emergency cases performed increased significantly throughout the study period. Enhanced daytime (r = 0.741, p < 0.01) and evening (r = 0.548, p < 0.01) operating absorbed this increase in workload. There was no significant change in the absolute number of cases performed at night but the proportion of the emergency workload that took place after midnight decreased significantly throughout the study (r = -0.742, p < 0.01). CONCLUSION: A small but consistent volume of complex cases require emergency surgery after midnight. Provision of an emergency general surgical service must incorporate this need.