Fluvial Depositional Systems of the African Humid Period: An Analog for an Early, Wet Mars in the Eastern Sahara

A widely hypothesized but complex transition from widespread fluvial activity to predominantly aeolian processes is inferred on Mars based on remote sensing data observations of ancient landforms. However, the lack of analysis of in situ martian fluvial deposits hinders our understanding of the flow regime nature and sustainability of the martian fluvial activity and the hunt for ancient life. Studying analogs from arid zones on Earth is fundamental to quantitatively understanding geomorphic processes and climate drivers that might have dominated during early Mars. Here we investigate the formation and preservation of fluvial depositional systems in the eastern Sahara, where the largest arid region on Earth hosts important repositories of past climatic changes. The fluvial systems are composed of well-preserved single-thread sinuous to branching ridges and fan-shaped deposits interpreted as deltas. The systems' configuration and sedimentary content suggest that ephemeral rivers carved these landforms by sequential intermittent episodes of erosion and deposition active for 10-100s years over ∼10,000 years during the late Quaternary. Subsequently, these landforms were sculpted by a marginal role of rainfall and aeolian processes with minimum erosion rates of 1.1 ± 0.2 mm/yr, supplying ∼96 ± 24 × 10¹⁰ m³ of disaggregated sediment to adjacent aeolian dunes. Our results imply that similar martian fluvial systems preserving single-thread, short distance source-to-sink courses may have formed due to transient drainage networks active over short durations. Altogether, this study adds to the growing recognition of the complexity of interpreting climate history from orbital images of landforms.

Dynamic Role of Oxygen in Wound Healing: A Microbial, Immunological, and Biochemical Perspective

A wound is a temporary break in the continuity of the protective skin barrier. Wound healing is central in maintaining the body's normal homeostatic mechanism, and open wounds raise the risk of microbial infection and amputation. A successful wound healing event is achieved through a series of evolutionarily conserved biochemical pathways orchestrated by various cytokines, growth factors, and immune cells. Chronic wounds are generally oxygen-deficient, and wound hypoxia impairs the wound healing process. Therefore, the use of external oxygen may improve wound health by reducing wound hypoxia, promoting tissue regeneration and granulation tissue formation, reducing anaerobic bacteria colonization, and promoting the growth of beneficial aerobic bacteria. Relevant data were searched and gathered from scientific databases, including PubMed, ScienceDirect, and Google Scholar using relevant keywords, such as "Chronic Wounds", "Topical Oxygen Therapy", "Inflammatory Markers/ Lactate/ Matrix Metalloproteinase", "Collagen", and "Wound Healing". Relevant articles were shortlisted and used in the present study. Chronic wounds show higher expression of pro-inflammatory mediators, such as C-reactive protein, and higher levels of tissue-degrading matrix metalloproteinases. In addition, chronic wounds are generally oxygen-deficient, and wound hypoxia is directly associated with wound deterioration. Several microbial, immunological, and biochemical markers show a direct association with the oxygen availability in the wound. Therefore, a detailed understanding of these microbial, immunological, and biochemical markers will certainly help clinicians understand the interplay between various factors and topical oxygen therapy and may improve patient outcomes.

Surge of Bell's Palsy in the era of COVID-19; Systematic review

BACKGROUND

With the progression of Coronavirus infectious disease-19 (COVID-19), various neurological manifestations have been noticed in these patients and Bell's palsy is one of the peripheral neuropathies among those. Bell's palsy has been associated with various other viral agents. Its evidence in patients with COVID-19 signifies the possibility of association between Bell's Palsy and Severe acute respiratory syndrome coronavirus-2 (SARS-CoV2).

OBJECTIVE

To evaluate the number of published cases of Bell's palsy as the only major neurological manifestation in patients with COVID-19 from March 2020 to December 2021 and to investigate the association of SARS-CoV2 and Bell's palsy.

MATERIALS AND METHODS

A systematic review of the published English literature was performed using an electronic search in PubMed / Medline, Scopus, Research gate, Research square and Google Scholar databases, using keywords like 'COVID-19' OR/AND 'SARS-CoV-2', OR/AND 'Bell's palsy', OR/AND 'Facial nerve palsy', OR/AND 'Neurological', OR/AND 'Manifestation'.

RESULTS

Search strategy revealed 32 relevant publications with a total of 46 patients. Bell's palsy was the initial manifestation in 37% cases and in 63% cases it developed after COVID-19 symptoms. 71.7% cases showed complete recovery and 21.7% showed only partial relief from BP.

CONCLUSIONS

Although the number of documented cases in this research are not much, but evidence of Bell's palsy as the only major neurological manifestation in patients with COVID-19 signifies an important clinical finding and the possibility of another viral aetiology of BP. More evidence is needed to establish the exact co-relation between these two entities.

Post-COVID-19 HSV encephalitis: a review

BACKGROUND

Herpes simplex virus encephalitis (HSVE) is one of the most common infectious causes of sporadic encephalitis. Coronavirus disease (COVID-19) has been associated with immune dysregulation of the host that might increase the risk of infections like HSVE following SARS-CoV-2 infection. There is paucity of literature on post COVID-19 HSVE. This study was conducted with the aim of analyzing the clinical presentation, brain imaging, and outcome of patients presenting with HSVE within 6 weeks of COVID-19 and providing a comprehensive review on the possible mechanisms of post-COVID-19 HSVE.

METHODS

This observational study included patients who had laboratory-confirmed HSVE (type 1 or type 2) and a history of COVID-19 within the previous 6 weeks. Patients were followed up for 3 months.

RESULTS

Eight patients were included and all of them had type 1 HSVE. The mean latency of onset of neurological symptoms from being diagnosed with COVID-19 is 23.87 days and a majority of the patients have received injectable steroids with a mean duration of 6.5 days. Behavioral abnormality was the commonest neurological presentation and typical brain imaging involved T2 FLAIR hyperintensities of the medial temporal lobes. All patients received intravenous acyclovir 10 mg/kg every eight hourly for atleast 14 days. One patient with concomitant rhinocerebral mucormycosis succumbed while the majority had a complete recovery.

CONCLUSION

Possible immune dysregulation in COVID-19 may increase the susceptibility of HSVE in patients with a history of recent SARS-CoV-2 infection. The clinical manifestations and laboratory findings of HSVE in such patients are similar to typical HSVE.

Continuing perioperative estrogen therapy does not increase venous thromboembolic events in transgender patients: a systematic review and meta-analysis

OBJECTIVE

The aim of this study is to compare the risk of venous thromboembolic events (VTE) between patients suspending and continuing estrogen therapy perioperatively, in male to female gender-affirming surgery (vaginoplasty).

MATERIALS AND METHODS

The authors conducted a systematic review and meta-analysis of existing research on male to female gender-affirming study, which compared the risk of VTE among the usage of estrogen perioperatively.

RESULTS

A total of 209 studies were identified as potentially eligible among PubMed, Embase, and Cochrane library databases. Among the studies, 191 studies were excluded due to their abstract inappropriateness. Out of the remaining 18 studies, only 3 articles were eligible and were finally included. Meta-analysis was performed and showed odds ratio of 0.77 (95% CI: 0.04, 14.01).

CONCLUSIONS

Perioperative estrogen therapy does not increase VTE risk on male to female gender-affirming surgery. Therefore, estrogen therapy may be continued perioperatively in vaginoplasty. More prospective studies are needed.

Clinical correlation and assessment of olfactory dysfunction with n-butanol in COVID-19 patients: our experience

Background: Studies showed olfactory disturbances in COVID patients. This has attracted focus of clinicians as an easy clinical screening tool in suspected population. Material and methods: 70 mild and moderate category COVID-19 RT-PCR positive patients, more than 10 years of age were tested on day of admission for olfaction with serial dilution of n-butanol and asked to grade severity of their olfactory dysfunction according to visual analogue score from 1-10. Results: Fatigue 42 (93.33%), sore throat 37 (82.22%), fever 36 (80%) and dyspnea 23 (51.11%) were the most common symptoms in moderate patients. Diabetes, hypertension and allergy were the three prominent risk factors. At time of admission, n-butanol diagnosed 20 patients having olfactory dysfunction compared to 11 by VAS. Patients tend to grade their dysfunction higher on VAS whereas the n-butanol test classified their olfactory dysfunction lower. Viral load and high CRP were not found to be significantly related with olfactory dysfunction. d-Dimer and LDH levels were found statistically associated with higher grading of olfactory dysfunction detected by n-butanol. Conclusion: The majority of cases developed hyposmia before they were admitted to hospital even before they realized that they were having hyposmia as revealed by n-butanol testing. We should go for objective tests of olfaction.

Quantitative RNA assessment and long-term stability in the FFPE tumor samples using Digital Spatial Profiler

Background

Long-term storage of tissue slides has been reported to induce reduced biomarker (e.g. proteins and messenger RNA) detection. This study aimed to evaluate the impact of long-term storage time (0, 16, 24 and 36 weeks) and treatment conditions (non-paraffin and paraffin dipping) at 4°C on RNA quality in formalin-fixed and paraffin-embedded (FFPE) tissue sections.

Materials and methods

NanoString GeoMx Digital Spatial Profiling (DSP), a novel platform that allows spatial profiling, was used to profile RNA in human bladder cancer FFPE tissue sections.

Results

We observed excellent consistency of quantitative DSP RNA counts of all targets between two different treatment conditions (R > 0.97, Pearson correlation) at each time point and among all four different storage time points (R > 0.96, Pearson correlation) within each treatment condition. No significant difference was observed in the percentage of target genes with sufficient signal across two different treatment conditions at any time point (0 week, P = 0.96; 16 weeks, P = 0.76; 24 weeks, P = 0.96; 36 weeks, P = 0.76, Kolmogorov–Smirnov test) and across all four different storage time points (P > 0.05, Kolmogorov–Smirnov test) in either treatment condition.

Conclusion

Although both treatment conditions provided similar results in terms of count reproducibility and signal preservation, we recommend paraffin dipping to generate reproducible RNA results and optimize sample storage. Technology behind the NanoString GeoMx DSP platform shows a robust and reproducible RNA signal from multiple targets in the FFPE tissue sections stored at 4°C for at least up to 36 weeks.

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Long-term storage of FFPE sections has been reported to induce reduced antigen detection especially for RNA.

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This study evaluated the impact of storage times and treatment conditions on FFPE sections.

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The GeoMx DSP system, a novel platform that allows spatial RNA profiling, has been utilized.

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Long-term antigenicity preservation of quantitative DSP RNA counts was reported among storage times and treatment conditions.

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This finding is valuable in low resourced settings where routine access to FFPE blocks is challenging.

291 Single Centre Retrospective Study of Outcomes of Neck of Femur Fractures

Aim

To assess operative decision-making for patients with neck of femur fractures.

Method

2-year retrospective analysis of 150 patients in a single centre looking at outcomes focusing on complication rates and mortality.

Results

Mortality stood at 6% at 1 month and 25% at 1 year compared to quoted literature (10% at 1 month and 30% at 1 year). Surgical complication rates varied between fracture pattern and operative choice. Notably, the use of cannulated screws in displaced intracapsular fractures had a very high rate of failure at 80% (4 out of 5) compared to 0% for dynamic hip screws (0 out of 5). In undisplaced intracapsular fractures, the failure rate of cannulated screws remains high at 15% (2 out of 13) which is in-keeping with current literature. Surgical complications of hemi-arthroplasty remain low with only 3 out of 73 patients having significant complications (intra-operative fracture, dislocation, and acetabular erosion).

Conclusions

Cannulated screw fixation should be carefully considered, especially in the setting of displaced intracapsular fractures. Hemi-arthroplasty or two-hole DHS may have superior results in the fracture pattern and indeed, in undisplaced fractures.

A111 A RECTUM-SPECIFIC SELECTIVE RESECTION ALGORITHM OPTIMIZES ONCOLOGIC OUTCOMES FOR LARGE NON-PEDUNCULATED RECTAL POLYPS

Background

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are complementary techniques for large (≥ 20mm) non-pedunculated rectal polyps (LNPRPs). A mechanism for appropriate technique selection has not been described.

Aims

To evaluate whether a selective resection algorithm using EMR and ESD, based on real-time optical evaluation, optimizes oncologic outcomes for LNPRPs

Methods

We evaluated the performance of a selective resection algorithm (SRA; 08/2017-04/2021) compared to a universal EMR algorithm (UEA; 07/2008-07/2017) for LNPRPs within a prospective observational study. In the SRA, LNPRPs with features of superficial submucosal invasive cancer (SMIC < 1000μm; S-SMIC; Kudo pit pattern Vi), or with an increased risk of SMIC (Paris 0-Is or 0-IIa+Is non-granular, 0-IIa+Is granular with a dominant nodule ≥ 10mm) underwent ESD. The remaining LNPRPs underwent EMR. Algorithm performance was evaluated by SMIC identified after EMR, curative oncologic resection (R0 resection, S-SMIC, absence of negative histologic features), technical success, adverse events, and recurrence at first surveillance colonoscopy.

Results

480 LNPRPs were evaluated (290 UEA, 190 SRA). Median lesion size was 40mm (IQR 30-60mm). In the SRA, 103 (54.2%) and 87 (45.8%) LNPRPs underwent EMR and ESD, respectively. SMIC was identified in 56 (11.7%) LNPRPs. Significant differences in SMIC after EMR (SRA 1 (1.0%) vs. UEA 35 (12.1%); p = 0.001), curative oncologic resection (SRA 7 (33.3%) vs. UEA 2 (5.7%); p = 0.010), and recurrence (SRA 2 (1.6%) vs. UEA 40 (17.2%); p < 0.001) were identified. No significant differences in technical success or adverse events were identified (all p > 0.137). Among potentially curable malignant LNPRPs which underwent ESD, 100% (7/7) were cured.

Conclusions

A SRA optimizes oncologic outcomes for LNPRPs and mitigates the risk of piecemeal resection of cancers.

Funding Agencies

The Cancer Institute of New South Wales provided funding for a research nurse and data manager to assist with the administration of the study. Neal Shahidi was supported by the University of British Columbia Clinician Investigator Program. There was no influence from either institution regarding study design or conduct, data collection, management, analysis, interpretation, preparation, review, or approval of the manuscript.

A140 INTEROBSERVER RELIABILITY OF THE PARIS CLASSIFICATION FOR SUPERFICIAL GASTROINTESTINAL TRACT NEOPLASMS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background

The Paris classification is an international classification system that characterizes the morphology of superficial gastrointestinal tract neoplasms. Given its ability to predict the risk of submucosal invasion, this tool plays an important role in the preliminary endoscopic assessment of early gastrointestinal neoplastic lesions. Despite its international prevalence, there are no pooled reliability analyses to assess agreement amongst endoscopists using this classification system.

Aims

To systematically review and meta-analyze the interobserver reliability (IOR) of the Paris classification system.

Methods

We conducted a systematic review and meta-analysis according to the PRISMA recommendations. A comprehensive literature query was conducted on biomedical databases through December 2020. Studies were included if they quantitively evaluated the IOR of the Paris classification with at least 5 endoscopists participating in the study cohort. Two authors independently screened studies and abstracted data using an a priori designed data collection form. We pooled the results of studies which provided IOR with kappa statistics and confidence intervals using DerSimonian and Laird random effects models. Risk of bias was independently assessed by two study authors using the Guidelines for Reporting Reliability and Agreement Studies (GRRAS) tool.

Results

From an initial 1541 studies, 5 were included in the qualitative review and 3 reported data that allowed for a quantitative analysis of the primary outcome, representing a total of 28 endoscopists. All three of these studies were high quality. The IOR for the Paris classification amongst all endoscopists was 0.541 (95% CI, 0.466–0.617). There was no significant improvement (p=0.551) in the IOR of the Paris classification system following an educational training intervention (pre-education pooled kappa, 0.498; 95% CI, 0.429–0.567 compared to post-education pooled kappa, 0.530; 95% CI, 0.451–0.608).

Conclusions

Interobserver reliability of the Paris classification is moderate with no significant improvement following educational intervention.

Funding Agencies

None

A115 ACCURACY OF OPTICAL DIAGNOSIS IN ENDOSCOPY AT A TERTIARY ACADEMIC CENTER

Background

Optical diagnosis relies on the ability of the endoscopist to visualize normal and abnormal patterns on the epithelial surface of the gastrointestinal tract. With ongoing technologic advances in image-enhanced and magnifying endoscopy, there has been more attention given to improving our ability to visually evaluate and classify lesions as this can help guide decisions around resection techniques. However, the accuracy of optical diagnosis of epithelial lesions remains under investigated.

Aims

To analyse (1) the presence or absence of descriptive details (size, gross morphology, and classification systems used) of lesions of interest within the endoscopy report and (2) the accuracy of the optical diagnosis, when stated, as compared to the final pathology report.

Methods

This is a single-centre retrospective chart review and quality improvement initiative conducted at St. Michael’s Hospital, Toronto, Ontario. All patients who had polypectomy performed between January 1st, 2019 and December 31st, 2020 for polyp(s) &gt; 10mm in size, were eligible for study inclusion. Patients were excluded if polyps did not meet the size criteria, the polyp was not resected, or absent documentation. Descriptive statistics were conducted.

Results

2100 patients had polypectomies during the study period. 714 patients with 833 polyps &gt;10mm in size were included in the data analysis. Estimated size was reported for 93% of polyps, gross morphology for 68%, and a classification system for 72%. All three description parameters were reported for 52% of polyps. Predicted pathology was recorded in 41% of polyps. When documented, the accuracy of optical diagnosis was 71%.

Conclusions

In our study, the presence of key descriptive details attributed to polyps at the time of polypectomy was lower than expected. In addition, an optical diagnosis was documented in less than half of the time. Finally, the overall accuracy of optical diagnosis was lower than predicted potentially related to the underreporting and underutilization the important predictors of submucosal invasion. Considering that making real-time endoscopic diagnoses has major implications on treatment decisions, it is imperative that we work on these skills to improve patient outcomes (increasing R0 resection rates, decreasing recurrence and avoiding unnecessary surgeries). Through this project, recommendations will be made regarding the implementation of synoptic reporting in addition to guiding future quality improvement initiatives.

Funding Agencies

None

A168 UTILITY OF FOLLOW-UP PANCOLONIC DYE SPRAY CHROMOENDOSCOPY FOR THE DETECTION AND TREATMENT OF DYSPLASTIC LESIONS IDENTIFIED DURING HIGH-DEFINITION WHITE-LIGHT ENDOSCOPY IN PATIENTS WITH COLONIC INFLAMMATORY BOWEL DISEASE

Background

Patients with inflammatory bowel disease (IBD) involving the colorectum are at higher risk for the development of flat and poorly delineated dysplastic lesions. Pancolonic dye spray chromoendoscopy (DCE) can represent an adjunct to white light endoscopy (WLE) that enhances detection and delineation of such lesions.

Aims

We evaluated the utility of follow-up DCE for lesion detection and treatment in patients with IBD who had visible (polypoid or flat lesions) or invisible (identified in non-targeted biopsies) dysplasia detected during high-definition (HD)-WLE.

Methods

We retrospectively studied patients with colonic IBD from The Ottawa Hospital who underwent DCE by a trained endoscopist, as follow-up for dysplasia detected during HD-WLE, over a 7-year time period (2013–2020). We collected demographic and disease-specific variables.

Results

Twenty-four patients were included (mean age 56.7±13.8 years, 50.0% male, 70.8% ulcerative colitis, mean disease duration 18.0±11.0 years, 70.8% moderate or severe disease activity historically, and 41.7% remote history of dysplasia). Seventeen (70.8%) patients were referred following detection of invisible dysplasia; the remainder (29.2%) were referred for surveillance of poorly defined visible dysplastic lesions. For those referred following detection of invisible dysplasia, DCE identified visible dysplasia at the same site in 8/17 (47.1%) patients, at a different site in 6/17 (35.3%) patients, and no dysplasia in 3/17 (17.6%) patients. DCE identified 1.39±1.50 new visible dysplastic lesions per patient that were not identified on index HD-WLE. DCE upgraded the highest grade of dysplasia and diagnosed colorectal cancer in 2/24 (8.3%) patients, which was missed on index HD-WLE. Endoscopic resection was successful in 23/34 (76.7%) dysplastic lesions identified on DCE. However, DCE was unable to facilitate lesion resection in three patients due to advanced lesion characteristics. Follow-up data was available for 17/24 (70.8%) patients (mean 0.88±0.58 years). Of these patients, 7/17 (41.2%) developed subsequent dysplasia, including 4/17 (23.5%) at a site of prior invisible dysplasia, 2/17 (11.8%) at sites of prior visible dysplasia, and 1/17 (5.88%) at a different site. One of these patients developed high-grade dysplasia requiring resection.

Conclusions

In this study, DCE is a valuable tool for dysplasia detection and treatment in persons with colonic IBD who have ill-defined dysplasia identified during HD-WLE. Given some patients developed dysplasia following DCE in our cohort, it is important to maintain close follow-up and obtain biopsies around sites of prior invisible and visible dysplasia. Further studies are required to validate our findings.

Funding Agencies

None

Jaundice and a testicular lump: a rare cause of malignant biliary obstruction

Biliary obstruction from metastatic deposits in the pancreas is rare. We present a case of primary testicular lymphoma (PTL) with pancreatic metastasis. A 56-year-old man presented to the general surgical department with signs and symptoms of obstructive jaundice. A computed tomography scan revealed multiple pancreatic metastases and a right primary testicular malignancy. Histology and positron emission tomography scanning subsequently confirmed PTL with pancreatic metastases. Metastasis to the pancreas from primary testicular malignancy is extremely rare. There is variation in prognosis between primary and secondary pancreatic malignancies and therefore in atypical cases of malignant biliary obstruction consideration must be given to the rarer secondary malignancies.

Sialadenoma papilliferum of a minor salivary gland with transformation to mucoepidermoid carcinoma

Sialadenoma papilliferum (SP) is a rare benign tumor usually occurring in the minor salivary glands. Only two cases of malignant transformation of SP and an occasional case of dysplasia in SP have been reported in the literature till now. We report a case of SP of a minor salivary gland in a middle-aged male where the exophytic component retained the histomorphological features of SP while the endophytic component displayed characteristics of a mucoepidermoid carcinoma. Malignant change in sialadenoma papilliferum is an extremely rare phenomenon that requires further research and documentation. Careful evaluation of morphologic features and reporting of more such cases is required to delineate the clinical behavior of this unusual tumor.