A new lysine biosynthetic enzyme from a bacterial endosymbiont shaped by genetic drift and genome reduction.

The effect of population bottlenecks and genome reduction on enzyme function is poorly understood. Candidatus Liberibacter solanacearum is a bacterium with a reduced genome that is transmitted vertically to the egg of an infected psyllid-a population bottleneck that imposes genetic drift and is predicted to affect protein structure and function. Here, we define the function of Ca. L. solanacearum dihydrodipicolinate synthase (CLsoDHDPS), which catalyzes the committed branchpoint reaction in diaminopimelate and lysine biosynthesis. We demonstrate that CLsoDHDPS is expressed in Ca. L. solanacearum and expression is increased ~2-fold in the insect host compared to in planta. CLsoDHDPS has decreased thermal stability and increased aggregation propensity, implying mutations have destabilized the enzyme but are compensated for through elevated chaperone expression and a stabilized oligomeric state. CLsoDHDPS uses a ternary-complex kinetic mechanism, which is to date unique among DHDPS enzymes, has unusually low catalytic ability, but an unusually high substrate affinity. Structural studies demonstrate that the active site is more open, and the structure of CLsoDHDPS with both pyruvate and the substrate analogue succinic-semialdehyde reveals that the product is both structurally and energetically different and therefore evolution has in this case fashioned a new enzyme. Our study suggests the effects of genome reduction and genetic drift on the function of essential enzymes and provides insights on bacteria-host co-evolutionary associations. We propose that bacteria with endosymbiotic lifestyles present a rich vein of interesting enzymes useful for understanding enzyme function and/or informing protein engineering efforts.

Endoscopic features of low-grade dysplastic Barrett's.

Background and study aims Barrett's esophagus (BE) with low-grade dysplasia (LGD) is considered usually endoscopically invisible and the endoscopic features are not well described. This study aimed to: 1) evaluate the frequency of visible BE-LGD; 2) compare rates of BE-LGD detection in the community versus a Barrett's referral unit (BRU); and 3) evaluate the endoscopic features of BE-LGD. Patients and methods This was a retrospective analysis of a prospectively observed cohort of 497 patients referred to a BRU with dysplastic BE between 2008 and 2022. BE-LGD was defined as confirmation of LGD by expert gastrointestinal pathologist(s). Endoscopy reports, images and histology reports were reviewed to evaluate the frequency of endoscopically identifiable BE-LGD and their endoscopic features. Results A total of 135 patients (27.2%) had confirmed BE-LGD, of whom 15 (11.1%) had visible LGD identified in the community. After BRU assessment, visible LGD was detected in 68 patients (50.4%). Three phenotypes were observed: (A) Non-visible LGD; (B) Elevated (Paris 0-IIa) lesions; and (C) Flat (Paris 0-IIb) lesions with abnormal mucosal and/or vascular patterns with clear demarcation from regular flat BE. The majority (64.7%) of visible LGD was flat lesions with abnormal mucosal and vascular patterns. Endoscopic detection of BE-LGD increased over time (38.7% (2009-2012) vs. 54.3% (2018-2022)). Conclusions In this cohort, 50.4% of true BE-LGD was endoscopically visible, with increased recognition endoscopically over time and a higher rate of visible LGD detected at a BRU when compared with the community. BRU assessment of BE-LGD remains crucial; however, improving endoscopy surveillance quality in the community is equally important.

Location and appearance of dysplastic Barrett's esophagus recurrence after endoscopic eradication therapy: no additional yield from random biopsy sampling neosquamous mucosa.

BACKGROUND AND AIMS: Surveillance after complete remission of intestinal metaplasia (CRIM) is essential. Current recommendations are to sample visible lesions first, followed by random 4-quadrant biopsy sampling of the original Barrett's esophagus (BE) length. To inform post-CRIM surveillance protocols, we aimed to identify the anatomic location, appearance, and histology of BE recurrences. METHODS: We performed an analysis of 216 patients who achieved CRIM after endoscopic eradication therapy for dysplastic BE at a Barrett's Referral Unit between 2008 and 2021. The anatomic location, recurrence histology, and endoscopic appearance of dysplastic recurrences were evaluated. RESULTS: After a median of 5.5 years (interquartile range, 2.9-7.2) of follow-up after CRIM, 57 patients (26.4%) developed nondysplastic BE (NDBE) recurrence and 18 patients (8.3%) developed dysplastic recurrence. From 8158 routine surveillance biopsy samplings of normal-appearing tubular esophageal neosquamous epithelium, the yield for recurrent NDBE or dysplasia was 0%. One hundred percent of dysplastic tubular esophageal recurrences were visible and in BE islands, whereas 77.8% of gastroesophageal junction dysplastic recurrences were nonvisible. Four distinct endoscopic features suspicious for recurrent advanced dysplasia or neoplasia were identified: buried or subsquamous BE, irregular mucosal pattern, loss of vascular pattern, and nodularity or depression. CONCLUSIONS: The yield of routine surveillance biopsy sampling of normal-appearing tubular esophageal neosquamous epithelium was zero. BE islands with indistinct mucosal or loss of vascular pattern, nodularity or depression, and/or signs of buried BE should raise clinician suspicion for advanced dysplasia or neoplasia recurrence. We suggest a new surveillance biopsy sampling protocol with a focus on meticulous inspection, followed by targeted biopsy sampling of visible lesions and random 4-quadrant biopsy sampling of the gastroesophageal junction.

Direct percutaneous endoscopic gastrostomy for nutritional support in patients with aerodigestive tract cancers.

BACKGROUND: Conventional pull-through percutaneous endoscopic gastrostomy (PEG) risks infection and tumour implantation in head and neck cancers. Endoscopically inserted direct gastrostomy has lower rates of complications but is underutilised. AIMS: To describe the endoscopic steps for direct gastrostomy insertion and review our single-centre experience to assess the technical feasibility and safety. METHODS: Patients who underwent endoscopic direct gastrostomy insertion between December 2016 and June 2021 were included. A 24Fr introducer kit for gastrostomy feeding tube (Avanos Healthcare, Australia) was used. Patient and tumour characteristics, procedural data and 30-day outcomes were recorded. RESULTS: Thirty patients underwent direct PEG insertion (mean age 64 years and 24 male). All were planned for or currently undergoing radiotherapy. Twenty-six (87%) of 30 cases were performed under conscious sedation over a median procedure time of 21 min (interquartile range 11 min). No tumour seeding was seen, and one case of PEG-site infection was observed. CONCLUSIONS: Direct PEG is safe and effective and should be considered for patients with aerodigestive tract cancer in need of nutritional support.

Clinical application and diagnostic accuracy of artificial intelligence in colonoscopy for inflammatory bowel disease: systematic review.

Background and aims Artificial intelligence (AI) technology is being evaluated for its potential to improve colonoscopic assessment of inflammatory bowel disease (IBD), particularly with computer-aided image classifiers. This review evaluates the clinical application and diagnostic test accuracy (DTA) of AI algorithms in colonoscopy for IBD. Methods A systematic review was performed on studies evaluating AI in colonoscopy of adult patients with IBD. MEDLINE, Embase, Emcare, PsycINFO, CINAHL, Cochrane Library and Clinicaltrials.gov databases were searched on 28 th April 2021 for English language articles published between January 1, 2000 and April 28, 2021. Risk of bias and applicability were assessed with the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Diagnostic accuracy was presented as median (interquartile range). Results Of 1029 records screened, nine studies with 7813 patients were included for review. AI was used to predict endoscopic and histologic disease activity in ulcerative colitis, and differentiation of Crohn's disease from Behcet's disease and intestinal tuberculosis. DTA of AI algorithms ranged between 52-91 %. The sensitivity and specificity for AI algorithms predicting endoscopic severity of disease were 78 % (range 72-83, interquartile range 5.5) and 91 % (range 86-96, interquartile range 5), respectively. Conclusions AI has been primarily used to assess disease activity in ulcerative colitis. The diagnostic performance is promising and suggests potential for other clinical application of AI in IBD colonoscopy such as dysplasia detection. However, current evidence is limited by retrospective data and models trained on still images only. Future prospective multicenter studies with full-motion videos are needed to replicate the real-world clinical setting.

Quality of upper GI endoscopy: a prospective cohort study on impact of endoscopist education.

BACKGROUND AND AIMS: Guidelines on quality of upper GI (UGI) endoscopy have been proposed by the British Society of Gastroenterology (BSG) and European Society of Gastrointestinal Endoscopy (ESGE). However, these guidelines have not been evaluated in clinical practice. We aimed to measure the impact of endoscopist education on the quality of gastroscopy based on these guidelines and the association between compliance with guidelines and the detection of clinically significant premalignant pathology such as Barrett's esophagus (BE), esophageal squamous dysplasia, gastric intestinal metaplasia (GIM), and Helicobacter pylori. METHODS: Endoscopists participated in a 1-hour education session on recommended performance measures and endoscopic detection of premalignant pathologies. A controlled before and after study was performed, measuring compliance with guidelines and rates of detection of pathology in control and intervention groups. RESULTS: Over 2 years, 2719 procedures were performed: 1412 in the control group and 1307 in the intervention group. The proportion of procedures complying with guidelines was higher in the intervention group. The use of biopsy sampling protocols (eg, management of precancerous conditions of the stomach, 52% vs 91%; P = .007) and standardized terminology (eg, Forrest classification, 24% vs 68%; P < .001) was significantly higher. Detection of H pylori was higher in the intervention group (5.5% vs 9.8%, P = .003). Minimum inspection time of 7 minutes was associated with detection of BE (7.4% vs 2.0%, P < .001). CONCLUSIONS: A simple endoscopist education session enhanced the quality of UGI endoscopy by improving compliance with BSG and ESGE recommendations and increasing the detection of clinically significant pathology. A minimum inspection time of 7 minutes was associated with increased diagnostic yield and may be a feasible quality indicator for clinical practice.

Evaluation of Endoscopic Practices and Outcomes in Follow-up of Gastric Ulcers.

GOAL: The aim of this study was to evaluate current practice in gastric ulcer follow-up to establish diagnostic yield and predictors of malignancy. BACKGROUND: Repeat gastroscopy is routinely performed to confirm gastric ulcer healing and exclude malignancy. However, the incidence of malignancy at follow-up endoscopy is low, without consensus regarding case selection and timing. STUDY: New gastric ulcers diagnosed on gastroscopy at 2 institutions in Australia were identified through keyword search of endoscopy reports over a 5-year period (2013 to 2017). Data collected included patient demographics, clinical presentation, and endoscopic and histologic findings from initial and subsequent gastroscopies. RESULTS: Of 795 patients, repeat gastroscopy was performed in 440 (55%). Malignancy was diagnosed in 52 (7%) with 83% identified at initial gastroscopy. Eight cancers were identified at repeat gastroscopy with malignancy yield of 2% (8/440). Three were diagnosed in patients with benign initial ulcer histology (3/286, 1%). One cancer was diagnosed during follow-up in a patient with benign histology but no repeat gastroscopy (1/286, 0.3%). Predictors of benign ulcers were absence of endoscopic suspicion [odds ratio (OR) 0.1 (0.03-0.13), P≤0.005], complete healing on repeat gastroscopy [OR 0.5 (0.34-0.70), P=0.036] and benign initial histology [OR 0.12 (0.43-0.90), P≤0.005]. CONCLUSIONS: Seven percent of new gastric ulcers were malignant with most identified with biopsy on initial gastroscopy. Malignancy yield from follow-up gastroscopy was 2%. Diagnostic yield of endoscopic follow-up may be low in ulcers with benign appearance and adequate histology. However, current practice of repeat gastroscopy is warranted in the absence of patient-based and lesion-based predictors of malignancy.

Not all low grade dysplasia in Barrett's oesophagus is the same: using specific histological criteria in predicting progression to neoplasia.

Barrett's oesophagus with low grade dysplasia (LGD) is a risk factor for progression to high grade dysplasia (HGD) and oesophageal adenocarcinoma (OAC); however, only a subgroup of LGD will progress. We used a combination of specific histological criteria to identify patients with LGD who are more likely to progress to HGD or OAC. LGD slides from 38 patients within the progressor group (PG) and 17 patients from the non-progressor group (NPG) were obtained and reviewed by two expert GI pathologists, to be stratified by the same four specific histological variables identified by Ten Kate et al.: loss of surface maturation, mucin depletion, nuclear enlargement, and increase of mitosis. After review of LGD slides by two expert GI pathologists, 27 suitable patients were identified. Of these 27 patients there was a higher proportion of patients from the PG with all four specific criteria reported, compared to the NPG: 14 (78%) vs 3 (33%) p=0.0394. Patients with all four specific criteria were more likely to progress compared to those who had one or less specific criteria reported (OR 7, 95% CI 1.1848-41.3585, p=0.032). A combination of ≥2 or ≥3 specific histological criteria was not prognostic. Patients with a combination of all four specific histological criteria (loss of surface maturation, mucin depletion, nuclear enlargement, and increase of mitosis) were associated with greater progression from LGD to HGD or OAC in Barrett's oesophagus.

N-acetylmannosamine-6-phosphate 2-epimerase uses a novel substrate-assisted mechanism to catalyze amino sugar epimerization.

There are five known general catalytic mechanisms used by enzymes to catalyze carbohydrate epimerization. The amino sugar epimerase N-acetylmannosamine-6-phosphate 2-epimerase (NanE) has been proposed to use a deprotonation-reprotonation mechanism, with an essential catalytic lysine required for both steps. However, the structural determinants of this mechanism are not clearly established. We characterized NanE from Staphylococcus aureus using a new coupled assay to monitor NanE catalysis in real time and found that it has kinetic constants comparable with other species. The crystal structure of NanE from Staphylococcus aureus, which comprises a triosephosphate isomerase barrel fold with an unusual dimeric architecture, was solved with both natural and modified substrates. Using these substrate-bound structures, we identified the following active-site residues lining the cleft at the C-terminal end of the ß-strands: Gln11, Arg40, Lys63, Asp124, Glu180, and Arg208, which were individually substituted and assessed in relation to the mechanism. From this, we re-evaluated the central role of Glu180 in this mechanism alongside the catalytic lysine. We observed that the substrate is bound in a conformation that ideally positions the C5 hydroxyl group to be activated by Glu180 and donate a proton to the C2 carbon. Taken together, we propose that NanE uses a novel substrate-assisted proton displacement mechanism to invert the C2 stereocenter of N-acetylmannosamine-6-phosphate. Our data and mechanistic interpretation may be useful in the development of inhibitors of this enzyme or in enzyme engineering to produce biocatalysts capable of changing the stereochemistry of molecules that are not amenable to synthetic methods.

Barrett's esophagus with low-grade dysplasia: high rate of upstaging at Barrett's esophagus referral units suggests progression rates may be overestimated.

BACKGROUND AND AIMS: The reported progression rate from low-grade dysplasia (LGD) in Barrett's esophagus (BE) to high-grade dysplasia (HGD) or esophageal adenocarcinoma (EAC) ranges from .4% to 13.4% per year. We hypothesize that some reported progression rates may be overestimated because of prevalent HGD or EAC that was not identified during endoscopic assessments performed in the community. Our aim is to determine the proportion of prevalent HGD or EAC detected by BE referral units (BERUs) in patients referred from the community with a recent diagnosis of LGD. METHODS: All patients referred from the community to 6 BERUs with a diagnosis of BE with LGD were identified. Patients with an assessment endoscopy performed at BERUs more than 6 months from their referral endoscopy in the community were excluded. Visible lesions and histology outcomes were compared between the community referral endoscopy and the assessment endoscopy performed at BERUs. RESULTS: The median time between BERU assessment and referral endoscopy was 79 days (interquartile range, 54-114). Of the 75 patients referred from the community with LGD, BERU assessment identified HGD or EAC in 20 patients (27%). BERU assessment identified more visible lesions than referral endoscopy performed in the community (39 [52%] vs 9 [12%], respectively; P = .029). CONCLUSIONS: BERU assessment endoscopy identified more visible lesions than community referral endoscopy and identified HGD or EAC in 27% of patients referred from the community with a recent diagnosis of LGD. Reported progression rates from LGD to HGD or EAC may be overestimated.

Quantifying early gastric cancer in Australia: What is the opportunity for gastric endoscopic submucosal dissection?

BACKGROUND AND AIMS: Endoscopic submucosal dissection (ESD) is the recommended treatment for early gastric cancer (EGC). However, there are challenges in attaining expertise in ESD in countries where the incidence of gastric cancer and proportion diagnosed at an early stage of disease are relatively low. This study aims to establish the proportion of gastric cancer meeting histological criteria for EGC, which may be suitable for ESD, in a Western population. METHODS: Gastric cancers reported to the Victorian Cancer Registry between January 2011 and December 2016 were analyzed. EGC was defined as tumor confined to mucosa (T1a) or submucosa (T1b). Histology reports were analyzed using Japanese and European guidelines to identify potential ESD candidates. Criteria for extended ESD were based on grade of differentiation, tumor depth, lymphovascular and perineural invasion, and ulceration. RESULTS: Twenty percent of 1217 gastric cancers was EGC (237 cases), with detailed histopathology reports suitable for evaluating ESD criteria recorded in 182 cases. Standard and extended ESD criteria were met in 46% (84/182) and 75% (132/182), respectively. Actual treatment of the 237 EGC was endoscopic in 14% (n = 33) and surgery in 86% (n = 204). Endoscopically treated EGCs were more likely to be stage T1a and located in the proximal stomach. CONCLUSIONS: EGCs represented 20% of reported gastric adenocarcinomas with the majority fulfilling criteria for ESD. ESD should be considered in the management algorithm and discussed at tumor board meetings involving interventional endoscopists. To increase utilization of ESD, systems need to be implemented to improve training, accreditation, and access to ESD.

Endoscopic features of buried Barrett's mucosa.

BACKGROUND AND AIMS: Buried Barrett's mucosa is defined as intestinal metaplasia that is "buried" under the normal-appearing squamous epithelium. This can occur in Barrett's esophagus with or without previous endoscopic therapy. Dysplasia and neoplasia within buried Barrett's mucosa have also been reported. However, endoscopic features of buried Barrett's mucosa have not been described. At our tertiary referral center for Barrett's esophagus, several endoscopic features have been observed in patients who were found to have buried Barrett's mucosa on histology. These features are squamous epithelium which is (1) darker pink on white-light and darker brown on narrow-band imaging and/or (2) has a slightly raised or nodular appearance. It was also observed that either of these 2 features is frequently seen adjacent to a Barrett's mucosa island. This study aimed to (1) evaluate the diagnostic accuracy of these endoscopic features, and (2) evaluate the frequency of endoscopically identifiable buried Barrett's mucosa in patients with dysplastic Barrett's esophagus, before and after endoscopic eradication therapy. METHODS: This was a retrospective analysis of a prospectively observed cohort of all cases of dysplastic Barrett's esophagus referred to St Vincent's Hospital, Melbourne. Endoscopy documentation software and histopathology reports of esophageal biopsy and EMR specimens between March 2013 and March 2019 were searched for terms "buried" or "subsquamous" Barrett's mucosa. Endoscopic reports, images, and histopathology reports of suspected buried Barrett's mucosa were then reviewed to apply the endoscopic features and correlate with the histologic diagnosis. RESULTS: In a cohort of 506 patients with dysplastic Barrett's esophagus, 33 (7%) patients (73% male, median age at referral 70.5 years) had buried Barrett's mucosa on histology. Twenty-seven (82%) patients had previous treatment for dysplastic Barrett's esophagus; radiofrequency in 2 (6%), EMR in 4 (12%), and both modalities in 21 (64%). Six (18%) had no previous treatment. Histologically confirmed buried Barrett's mucosa was suspected at endoscopy in 26 patients (79%). Endoscopic features were (1) darker pink or darker brown mucosa underneath squamous epithelium (24%), (2) raised areas underneath squamous mucosa (27%), and both features present concurrently (27%). These features were associated with adjacent islands of Barrett's esophagus in 48%. Forty-four cases of buried Barrett's mucosa were suspected endoscopically, and these were sampled by biopsy (50%) and EMR (50%). Buried Barrett's mucosa was confirmed in 26 cases, with a positive predictive value of endoscopic suspicion of 59%. Eighteen cases of endoscopically suspected buried Barrett's mucosa had no buried Barrett's mucosa on histology; inflammation or reflux was identified in 12 (67%) patients. Dysplasia was identified within buried Barrett's mucosa in 12 (36%) patients; 5 intramucosal adenocarcinoma, 1 high-grade dysplasia, and 6 low-grade dysplasia. Endoscopic features of buried Barrett's mucosa were observed in 11 of 12 cases harboring dysplasia or neoplasia, compared with 15 of 21 cases of buried Barrett's mucosa without dysplasia. CONCLUSIONS: In this retrospective analysis of prospectively observed patients with dysplastic Barrett's esophagus, buried Barrett's mucosa was identified in 7%, including treatment-naive patients. The proposed endoscopic features of buried Barrett's mucosa were seen in 79% of patients with histology confirmed disease. These endoscopic features may predict the presence of buried Barrett's mucosa, which may contain dysplasia or neoplasia. An overlap between the endoscopic features of inflammation, reflux, and buried Barrett's mucosa was observed. Future prospective studies are required to develop and validate endoscopic criteria for identifying buried Barrett's mucosa.

The role of esophagectomy in the management of Barrett's esophagus with high-grade dysplasia.

Barrett's esophagus (BE) with high-grade dysplasia (HGD) has previously been a routine indication for esophagectomy. Recent advances in endoscopic therapy have resulted in a shift away from surgery. Current international guidelines recommend endoscopic therapy for BE with HGD irrespective of recurrence or progression of dysplasia. Current guidelines do not address the ongoing role of esophagectomy as an adjunct in the setting of failed endoscopic therapy. This review examines the role of esophagectomy as an adjunct to endoscopy in the management of patients with BE and HGD, with a specific focus on patients with persistent, progressive, or recurrent disease, disease resistant to endoscopic therapy, in patients with concomitant esophageal pathology, and in those patients in whom lifelong surveillance may not be possible or desired.

Medical Options for Care of Gender Diverse and Transgender Youth.

Increasing numbers of transgender and gender diverse (TGD) youth are presenting for medical care, including seeking more information and access to services from gynecologic and reproductive health experts. Such experts are well positioned to provide affirming, comprehensive services, including education, hormonal interventions, menstrual management, contraception, and various gynecological procedures. Early medical guidance and support for the TGD community has been associated with long-term positive emotional and physical health outcomes. In this article medical interventions that reproductive health experts can offer to their TGD patients are discussed.

On the catalytic mechanism of bacteriophage endolysins: Opportunities for engineering.

Bacteriophage endolysins have the potential to be a long-term antibacterial replacement for antibiotics. The exogenous application of endolysins on some bacteria results in rapid cell lysis. The prospects for endolysins are furthered by the ability to engineer them; novel endolysins can be developed with optimised stability, specificity, and lytic function. But the success of endolysin engineering and application requires a comprehensive understanding of the relationship between the enzymes biochemical, biophysical and bacteriolytic properties. Here, we examine their catalytic mechanisms, opportunities for developing novel endolysins, and highlight areas where a better understanding would support their long-term success as antibacterial agents.

Simethicone use during gastrointestinal endoscopy: Position statement of the Gastroenterological Society of Australia.

Concern has been raised regarding the use of simethicone, a de-foaming agent, during endoscopic procedures. Following reports of simethicone residue in endoscope channels despite high level disinfection, an endoscope manufacturer recommended that it not be used due to concerns of biofilm formation and a possible increased risk of microorganism transmission. However, a detailed mucosal assessment is essential in performing high-standard endoscopic procedures. This is impaired by bubbles within the gastrointestinal lumen. The Gastroenterological Society of Australia's Infection Control in Endoscopy Guidelines (ICEG) Committee conducted a literature search utilizing the MEDLINE database. Further references were sourced from published paper bibliographies. Following a review of the available evidence, and drawing on extensive clinical experience, the multidisciplinary ICEG committee considered the risks and benefits of simethicone use in formulating four recommendations. Published reports have documented residual liquid or crystalline simethicone in endoscope channels after high level disinfection. There are no data confirming that simethicone can be cleared from channels by brushing. Multiple series report benefits of simethicone use during gastroscopy and colonoscopy in improving mucosal assessment, adenoma detection rate, and reducing procedure time. There are no published reports of adverse events related specifically to the use of simethicone, delivered either orally or via any endoscope channel. An assessment of the risks and benefits supports the continued use of simethicone during endoscopic procedures. Strict adherence to instrument reprocessing protocols is essential.

Psychosocial Overview of Gender-Affirmative Care.

Transgender and gender-diverse youth and their families are increasingly presenting to adolescent gynecological providers for education, care, and referrals. These youth more often face mental health and social disparities that frequently go unrecognized or unaddressed by providers. A gender-affirmative approach focuses on providing emotional validation, psychological safety, and support to young patients and their families. With better understanding of the unique needs of transgender and gender-diverse populations, gynecological care can be personalized and delivered in a nuanced fashion to better address the sexual and reproductive needs of gender minority patients. In this article we review essential psychological and social considerations in caring for transgender and gender-diverse youth, including concepts relating to gender identity, affirmative approaches, means of assessing for risk and resiliency, and family dynamics. Ultimately, adolescent gynecological providers have an important role in promoting the emotional health and positive development of transgender and gender-diverse youth.

"Just a spoonful of sugar...": import of sialic acid across bacterial cell membranes.

Eukaryotic cell surfaces are decorated with a complex array of glycoconjugates that are usually capped with sialic acids, a large family of over 50 structurally distinct nine-carbon amino sugars, the most common member of which is N-acetylneuraminic acid. Once made available through the action of neuraminidases, bacterial pathogens and commensals utilise host-derived sialic acid by degrading it for energy or repurposing the sialic acid onto their own cell surface to camouflage the bacterium from the immune system. A functional sialic acid transporter has been shown to be essential for the uptake of sialic acid in a range of human bacterial pathogens and important for host colonisation and persistence. Here, we review the state-of-play in the field with respect to the molecular mechanisms by which these bio-nanomachines transport sialic acids across bacterial cell membranes.

Changes in gene expression of neo-squamous mucosa after endoscopic treatment for dysplastic Barrett's esophagus and intramucosal adenocarcinoma.

BACKGROUND: Endoscopic therapy, including by radiofrequency ablation (RFA) or endoscopic mucosal resection (EMR), is first line treatment for Barrett's esophagus (BE) with high-grade dysplasia (HGD) or intramucosal cancer (IMC) and may be appropriate for some patients with low-grade dysplasia (LGD). OBJECTIVE: The purpose of this study was to investigate the molecular effects of endotherapy. METHODS: mRNA expression of 16 genes significantly associated with different BE stages was measured in paired pre-treatment BE tissues and post-treatment neo-squamous biopsies from 36 patients treated by RFA (19 patients, 3 IMC, 4 HGD, 12 LGD) or EMR (17 patients, 4 IMC, 13 HGD). EMR was performed prior to RFA in eight patients. Normal squamous esophageal tissues were from 20 control individuals. RESULTS: Endoscopic therapy resulted in significant change towards the normal squamous expression profile for all genes. The neo-squamous expression profile was significantly different to the normal control profile for 11 of 16 genes. CONCLUSION: Endotherapy results in marked changes in mRNA expression, with replacement of the disordered BE dysplasia or IMC profile with a more "normal" profile. The neo-squamous mucosa was significantly different to the normal control squamous mucosa for most genes. The significance of this finding is uncertain but it may support continued endoscopic surveillance after successful endotherapy.

Structure and inhibition of N-acetylneuraminate lyase from methicillin-resistant Staphylococcus aureus.

N-Acetylneuraminate lyase is the first committed enzyme in the degradation of sialic acid by bacterial pathogens. In this study, we analyzed the kinetic parameters of N-acetylneuraminate lyase from methicillin-resistant Staphylococcus aureus (MRSA). We determined that the enzyme has a relatively high KM of 3.2 mm, suggesting that flux through the catabolic pathway is likely to be controlled by this enzyme. Our data indicate that sialic acid alditol, a known inhibitor of N-acetylneuraminate lyase enzymes, is a stronger inhibitor of MRSA N-acetylneuraminate lyase than of Clostridium perfringens N-acetylneuraminate lyase. Our analysis of the crystal structure of ligand-free and 2R-sialic acid alditol-bound MRSA N-acetylneuraminate lyase suggests that subtle dynamic differences in solution and/or altered binding interactions within the active site may account for species-specific inhibition.