Gut Microbiome and Retinopathy of Prematurity.

Retinopathy of prematurity (ROP), a leading cause of childhood blindness worldwide, is strongly associated with gestational age and weight at birth. Yet, many extremely preterm infants never develop ROP or develop only mild ROP with spontaneous regression. In addition, a myriad of other factors play a role in the retinal pathology, one of which may include the early gut microbiome. The complications associated with early gestational age include dysbiosis of the dynamic neonatal gut microbiome, as evidenced by the development of often concomitant conditions, such as necrotizing enterocolitis. Given this, alongside growing evidence for a gut-retina axis, there is an increasing interest in how the early intestinal environment may play a role in the pathophysiology of ROP. Potential mechanisms include dysregulation of vascular endothelial growth factor and insulin-like growth factor 1. Furthermore, the gut microbiome may be impacted by other known risk factors for ROP, such as intermittent hypoxia and sepsis treated with antibiotics. This mini-review summarizes the literature supporting these proposed avenues, establishing a foundation to guide future studies.

Assessing Neonatal Intensive Care Unit (NICU) Graduates Across Varied Settings: A Study on the Feasibility of the Baby Moves App.

We assessed the feasibility of obtaining parent-collected General Movement Assessment videos using the Baby Moves app. Among 261 participants from 4 Chicago NICUs, 70% submitted videos. Families living in higher areas of childhood opportunity used the app more than those from areas of lower opportunity.

Use of an Artificial Intelligence-Generated Vascular Severity Score Improved Plus Disease Diagnosis in Retinopathy of Prematurity.

PURPOSE: To evaluate whether providing clinicians with an artificial intelligence (AI)-based vascular severity score (VSS) improves consistency in the diagnosis of plus disease in retinopathy of prematurity (ROP). DESIGN: Multireader diagnostic accuracy imaging study. PARTICIPANTS: Eleven ROP experts, 9 of whom had been in practice for 10 years or more. METHODS: RetCam (Natus Medical Incorporated) fundus images were obtained from premature infants during routine ROP screening as part of the Imaging and Informatics in ROP study between January 2012 and July 2020. From all available examinations, a subset of 150 eye examinations from 110 infants were selected for grading. An AI-based VSS was assigned to each set of images using the i-ROP DL system (Siloam Vision). The clinicians were asked to diagnose plus disease for each examination and to assign an estimated VSS (range, 1-9) at baseline, and then again 1 month later with AI-based VSS assistance. A reference standard diagnosis (RSD) was assigned to each eye examination from the Imaging and Informatics in ROP study based on 3 masked expert labels and the ophthalmoscopic diagnosis. MAIN OUTCOME MEASURES: Mean linearly weighted κ value for plus disease diagnosis compared with RSD. Area under the receiver operating characteristic curve (AUC) and area under the precision-recall curve (AUPR) for labels 1 through 9 compared with RSD for plus disease. RESULTS: Expert agreement improved significantly, from substantial (κ value, 0.69 [0.59, 0.75]) to near perfect (κ value, 0.81 [0.71, 0.86]), when AI-based VSS was integrated. Additionally, a significant improvement in plus disease discrimination was achieved as measured by mean AUC (from 0.94 [95% confidence interval (CI), 0.92-0.96] to 0.98 [95% CI, 0.96-0.99]; difference, 0.04 [95% CI, 0.01-0.06]) and AUPR (from 0.86 [95% CI, 0.81-0.90] to 0.95 [95% CI, 0.91-0.97]; difference, 0.09 [95% CI, 0.03-0.14]). CONCLUSIONS: Providing ROP clinicians with an AI-based measurement of vascular severity in ROP was associated with both improved plus disease diagnosis and improved continuous severity labeling as compared with an RSD for plus disease. If implemented in practice, AI-based VSS could reduce interobserver variability and could standardize treatment for infants with ROP. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

FULL-THICKNESS MACULAR HOLE CLOSURE WITH TOPICAL MEDICAL THERAPY.

PURPOSE: To examine the efficacy and clinical characteristics of successful full-thickness macular hole closure with topical therapy. METHODS: Retrospective case series of full-thickness macular holes managed by a single retinal physician (DS) diagnosed and treated from 2017 to 22. RESULTS: Of 168 patients with full-thickness macular holes, 71 patients were started on steroid, carbonic anhydrase inhibitor, and nonsteroidal antiinflammatory (NSAID) drops. 49 patients (mean 67 years, 59% women) were included in the analysis, and 22 patients were excluded for poor follow-up. In total, 7/49 were secondary post-PPV holes and 42/49 were idiopathic. In addition, 18/49 eyes (36.7%) achieved closure on topical therapy, of which 13 were idiopathic. Hole size was directly correlated with odds of closure: for every 10 µm decrease in size and odds of closure increased by 1.2× ( P = 0.001, CI 1.1-1.4). Average time to closure was 107.2 days (range 20-512 days) and was not correlated with hole size ( P = 0.217, CI -0.478 to +1.938). The presence of VMT was found to be inversely related to successful closure (OR 6.1, P = 0.029, CI 1.2-31.3). There was no significant difference in final best-corrected visual acuity for eyes undergoing primary pars plana vitrectomy versus those trialing drops before undergoing pars plana vitrectomy ( P = 0.318, CI -0.094 to +0.112). CONCLUSION: In the first study to date to report the overall efficacy and clinical characteristics of successful macular hole closure with topical therapy, drops achieved an overall closure rate of 36.7%, with higher efficacy in smaller holes and those without VMT. Rates of MH narrowing and reduction in central foveal thickness acted as predictors of effectiveness of drop therapy.

The Creation and Circulation of Evidence and Knowledge in American Medicine through the Lens of the "Husband's Stitch".

Physicians in the twentieth century routinely used episiotomy-a cut made during childbirth-to better facilitate labor, using the evidence of their experiences that it was useful. But physicians were not alone in producing evidence regarding episiotomy and its repair. Here I consider how three groups-male physicians, husbands, and laboring women-were involved in creating evidence and circulating knowledge about episiotomies, specifically, the intention of its repair, the so-called "husband's stitch," to sexually benefit men. By doing so I seek to consider the meanings of evidence within medicine, evidence as a basis for challenging the hegemony of medicine by lay women, and how medical knowledge is produced and shared among physicians and non-physicians.

LRRK2 Inhibition by BIIB122 in Healthy Participants and Patients with Parkinson's Disease.

BACKGROUND: Leucine-rich repeat kinase 2 (LRRK2) inhibition is a promising therapeutic approach for the treatment of Parkinson's disease (PD). OBJECTIVE: The aim of this study was to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of the potent, selective, CNS-penetrant LRRK2 inhibitor BIIB122 (DNL151) in healthy participants and patients with PD. METHODS: Two randomized, double-blind, placebo-controlled studies were completed. The phase 1 study (DNLI-C-0001) evaluated single and multiple doses of BIIB122 for up to 28 days in healthy participants. The phase 1b study (DNLI-C-0003) evaluated BIIB122 for 28 days in patients with mild to moderate PD. The primary objectives were to investigate the safety, tolerability, and plasma pharmacokinetics of BIIB122. Pharmacodynamic outcomes included peripheral and central target inhibition and lysosomal pathway engagement biomarkers. RESULTS: A total of 186/184 healthy participants (146/145 BIIB122, 40/39 placebo) and 36/36 patients (26/26 BIIB122, 10/10 placebo) were randomized/treated in the phase 1 and phase 1b studies, respectively. In both studies, BIIB122 was generally well tolerated; no serious adverse events were reported, and the majority of treatment-emergent adverse events were mild. BIIB122 cerebrospinal fluid/unbound plasma concentration ratio was ~1 (range, 0.7-1.8). Dose-dependent median reductions from baseline were observed in whole-blood phosphorylated serine 935 LRRK2 (≤98%), peripheral blood mononuclear cell phosphorylated threonine 73 pRab10 (≤93%), cerebrospinal fluid total LRRK2 (≤50%), and urine bis (monoacylglycerol) phosphate (≤74%). CONCLUSIONS: At generally safe and well-tolerated doses, BIIB122 achieved substantial peripheral LRRK2 kinase inhibition and modulation of lysosomal pathways downstream of LRRK2, with evidence of CNS distribution and target inhibition. These studies support continued investigation of LRRK2 inhibition with BIIB122 for the treatment of PD. © 2023 Denali Therapeutics Inc and The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Biomarkers of Pediatric Cataracts: A Proteomics Analysis of Aqueous Fluid.

Cataracts are among the most common causes of childhood vision loss worldwide. This study seeks to identify differentially expressed proteins in the aqueous humor of pediatric cataract patients. Samples of aqueous humor were collected from pediatric and adult cataract patients and subjected to mass spectrometry-based proteomic analysis. Samples of pediatric cataracts were grouped by subtype and compared to adult samples. Differentially expressed proteins in each subtype were identified. Gene ontology analysis was performed using WikiPaths for each cataract subtype. Seven pediatric patients and ten adult patients were included in the study. Of the pediatric samples, all seven (100%) were male, three (43%) had traumatic cataracts, two (29%) had congenital cataracts, and two (29%) had posterior polar cataracts. Of the adult patients, seven (70%) were female and seven (70%) had predominantly nuclear sclerotic cataracts. A total of 128 proteins were upregulated in the pediatric samples, and 127 proteins were upregulated in the adult samples, with 75 proteins shared by both groups. Gene ontology analysis identified inflammatory and oxidative stress pathways as upregulated in pediatric cataracts. Inflammatory and oxidative stress mechanisms may be involved in pediatric cataract formation and warrant further investigation.

Aggressiveness of Small-Spored Alternaria spp. and Their Sensitivity to Succinate Dehydrogenase Inhibitor Fungicides.

Brown leaf spot of potato is caused by a number of small-spored Alternaria spp. Alternaria alternata sensu stricto, A. arborescens, and A. tenuissima have been reported with increasing frequency in commercial potato fields. Potato cultivars with resistance to small-spored Alternaria spp. have yet to be developed; therefore, the application of foliar fungicides is a primary management strategy. Greenhouse inoculation assays demonstrated that isolates of these three small-spored Alternaria spp. were pathogenic. Significant differences in aggressiveness were observed across isolates; however, there was no trend in aggressiveness based on species. Significant fungicide by isolate interactions in in vitro fungicide sensitivity and significant differences between baseline and nonbaseline isolates were observed in all three small-spored Alternaria spp. The ranges of in vitro sensitivity of A. alternata baseline isolates to boscalid (EC50 <0.010 to 0.89 µg/ml), fluopyram (<0.010 to 1.14 µg/ml) and solatenol (<0.010 to 1.14 µg/ml) were relatively wide when compared with adepidyn (<0.010 to 0.023 µg/ml). The baseline sensitivities of A. arborescens and A. tenuissima isolates to all four fungicides were <0.065 µg/ml. Between 10 and 21% of nonbaseline A. alternata isolates fell outside the baseline range established for the four succinate dehydrogenase inhibitor (SDHI) fungicides evaluated. In A. arborescens, 10 to 80% of nonbaseline isolates had higher sensitivities than the baseline. A. tenuissima isolates fell outside the baseline for boscalid (55%), fluopyram (14%), and solatenol (14%), but none fell outside the baseline range for adepidyn. Evaluations of in vivo fungicide efficacy demonstrated that most isolates were equally controlled by the four SDHI fungicides. However, reduced boscalid efficacy was observed for four isolates (two each of A. arborescens and A. tenuissima) and reduced fluopyram control was observed in one A. alternata isolate. Results of these studies demonstrate that isolates of all three species could be contributing to the brown leaf spot pathogen complex and that monitoring both species diversity and fungicide sensitivity could be advantageous for the management of brown leaf spot in potatoes with SDHI fungicides.

Impact of SDH Mutations in Alternaria solani on Recently Developed SDHI Fungicides Adepidyn and Solatenol.

Early blight, caused by Alternaria solani, is observed annually in all midwestern potato production areas. The use of foliar fungicides remains a primary management strategy. However, A. solani has developed reduced sensitivity or resistance to many single-site fungicides such as quinone outside inhibitor (QoI, FRAC group 11), succinate dehydrogenase inhibitor (SDHI, FRAC group 7), demethylation inhibitor (DMI, FRAC group 3), and anilinopyrimidine (AP, FRAC group 9) fungicides. Boscalid, fluopyram, solatenol, and adepidyn are EPA-registered SDHI fungicides used commercially on a variety of crops, including potato. Five SDH mutations have been characterized previously in A. solani that affect the efficacy of boscalid while only one of these mutations has been demonstrated to negatively affect fluopyram efficacy. Conidial germination assays were used to determine if a shift in sensitivity has occurred in these SDHI fungicides. A. solani isolates collected prior to the commercial application of SDHI fungicides (baseline) were compared with recently collected isolates (nonbaseline). Greenhouse evaluations were conducted also to evaluate the efficacy of boscalid, fluopyram, solatenol, and adepidyn on A. solani isolates possessing individual SDH mutations. Additionally, field trials were conducted to determine the effects of application of these SDHI fungicides on the frequency of SDH mutations. Fluopyram, solatenol, and adepidyn had high intrinsic activity against A. solani when compared with boscalid, based on in vitro assays. The application of adepidyn and solatenol resulted in greater early blight control than the application of boscalid and fluopyram in greenhouse experiments. Molecular characterization of A. solani isolates collected from the field trials determined that the frequency of the H134R-mutation can increase in response to more recently developed SDHI fungicides. In contrast, the H278R/Y- and H133R-mutations decreased to the point of being nearly absent in these field experiments.

Cardiovascular involvement in alpha-n-acetyl neuraminidase deficiency syndromes (sialidosis type I and II).

Sialidosis, a rare autosomal recessive disorder, is caused by a deficiency of NEU1 encoded enzyme alpha-N-acetyl neuraminidase. We report a premature male with neonatal-onset type II sialidosis which was associated with left ventricular dysfunction. The clinical presentation and subsequent progression which culminated in his untimely death at 16 months of age are succinctly described. Early-onset cardiovascular involvement as noted in this patient is not well characterised. The case report is supplemented by a comprehensive review of the determinants, characteristics, and the clinical course of cardiovascular involvement in this rare condition.

A gender comparison of motivations for seeking leadership positions among gastroenterologists.

BACKGROUND AND AIMS: A gender gap exists in leadership positions in gastroenterology. However, individual motivations for seeking leadership positions within the gastroenterology community among men and women have not been explored. The primary aim of this study was to determine whether motivations for pursuing and attaining leadership positions in gastroenterology differ by gender. METHODS: A 20-question survey was created by the authors and shared with gastroenterologists electronically via a social media group (Facebook) and emails gathered through publicly available society websites and professional and social contacts. Data gathered from the survey included demographics, practice characteristics, presence of spouse or domestic partner, past and present leadership positions, motivations for pursuit of leadership positions, and reasons for lack of desire for a leadership position. RESULTS: The survey was sent to 981 gastroenterologists (679 women, 302 men). The overall response rate was 21.4% (n = 210) (20.9% for women, 22.5% for men). Overall, 41% of respondents (84 of 206) currently hold a leadership position, including more males than females (52% vs 36%, respectively; P = .03). However, among those who completed their training in the past 5 years, more women than men hold a current leadership role (25% vs 6%; P = .11). Other factors associated with currently holding a leadership position included age and years since completion of training, practice type, full-time status, and having a spouse who is not a physician. The positive factors of leadership cited most frequently were (1) ability to effect change, (2) furthering the goals of the organization, and (3) opportunity for career advancement. The negative factors cited most frequently were increased workload and decreased time for personal life. These reported positive and negative factors were similar for male and female respondents. Forty-nine respondents did not desire a leadership position now or in the future. The most common reason cited was lack of interest in the responsibilities, long hours, or stress that accompanies a leadership position (22 of 42, 52%). The second most common reason was that respondents were too busy at home or work to take on the extra responsibilities. CONCLUSIONS: A gender gap in gastroenterology leadership exists but is closing. There is fairly equal representation of men and women in leadership positions among those who completed training in the last 5 years. Many gastroenterologists are motivated for a leadership position and at the same time, many qualified individuals do not desire a leadership position because of factors that affect work-life balance. Ongoing efforts to engage motivated individuals into leadership positions and to revise the nature of leadership positions may allow for a larger talent pool from which to recruit.

The Ste20 Family Kinases MAP4K4, MINK1, and TNIK Converge to Regulate Stress-Induced JNK Signaling in Neurons.

The c-Jun-N-terminal kinase (JNK) signaling pathway regulates nervous system development, axon regeneration, and neuronal degeneration after acute injury or in chronic neurodegenerative disease. Dual leucine zipper kinase (DLK) is required for stress-induced JNK signaling in neurons, yet the factors that initiate DLK/JNK pathway activity remain poorly defined. In the present study, we identify the Ste20 kinases MAP4K4, misshapen-like kinase 1 (MINK1 or MAP4K6) and TNIK Traf2- and Nck-interacting kinase (TNIK or MAP4K7), as upstream regulators of DLK/JNK signaling in neurons. Using a trophic factor withdrawal-based model of neurodegeneration in both male and female embryonic mouse dorsal root ganglion neurons, we show that MAP4K4, MINK1, and TNIK act redundantly to regulate DLK activation and downstream JNK-dependent phosphorylation of c-Jun in response to stress. Targeting MAP4K4, MINK1, and TNIK, but not any of these kinases individually, is sufficient to protect neurons potently from degeneration. Pharmacological inhibition of MAP4Ks blocks stabilization and phosphorylation of DLK within axons and subsequent retrograde translocation of the JNK signaling complex to the nucleus. These results position MAP4Ks as important regulators of the DLK/JNK signaling pathway.SIGNIFICANCE STATEMENT Neuronal degeneration occurs in disparate circumstances: during development to refine neuronal connections, after injury to clear damaged neurons, or pathologically during disease. The dual leucine zipper kinase (DLK)/c-Jun-N-terminal kinase (JNK) pathway represents a conserved regulator of neuronal injury signaling that drives both neurodegeneration and axon regeneration, yet little is known about the factors that initiate DLK activity. Here, we uncover a novel role for a subfamily of MAP4 kinases consisting of MAP4K4, Traf2- and Nck-interacting kinase (TNIK or MAP4K7), and misshapen-like kinase 1 (MINK1 or MAP4K6) in regulating DLK/JNK signaling in neurons. Inhibition of these MAP4Ks blocks stress-induced retrograde JNK signaling and protects from neurodegeneration, suggesting that these kinases may represent attractive therapeutic targets.

RNA sequencing distinguishes benign from malignant pancreatic lesions sampled by EUS-guided FNA.

BACKGROUND AND AIMS: EUS-guided FNA (EUS-FNA) is the primary method used to obtain pancreatic tissue for preoperative diagnosis. Accumulating evidence suggests diagnostic and prognostic information may be obtained by gene-expression profiling of these biopsy specimens. RNA sequencing (RNAseq) is a newer method of gene-expression profiling, but published data are scant on the use of this method on pancreas tissue obtained via EUS-FNA. The aim of this study was to determine whether RNAseq of EUS-FNA biopsy samples of undiagnosed pancreatic masses can reliably discriminate between benign and malignant tissue. METHODS: In this prospective study, consenting adults presented to 2 tertiary care hospitals for EUS of suspected pancreatic mass. Tissue was submitted for RNAseq. The results were compared with cytologic diagnosis, surgical pathology diagnosis, or benign clinical follow-up of at least 1 year. RESULTS: Forty-eight patients with solid pancreatic mass lesions were enrolled. Nine samples were excluded because of inadequate RNA and 3 because of final pathologic diagnosis of neuroendocrine tumor. Data from the first 13 patients were used to construct a linear classifier, and this was tested on the final 23 patients (15 malignant and 8 benign lesions). RNAseq of EUS-FNA biopsy samples distinguishes ductal adenocarcinoma from benign pancreatic solid masses with a sensitivity of .87 (range, .58-.98) and specificity of .75 (range, .35-.96). CONCLUSIONS: This proof-of-principle study suggests RNAseq of EUS-FNA samples can reliably detect adenocarcinoma and may provide a new method to evaluate more diagnostically challenging pancreatic lesions.

ATP citrate lyase mediated cytosolic acetyl-CoA biosynthesis increases mevalonate production in Saccharomyces cerevisiae.

BACKGROUND: With increasing concern about the environmental impact of a petroleum based economy, focus has shifted towards greener production strategies including metabolic engineering of microbes for the conversion of plant-based feedstocks to second generation biofuels and industrial chemicals. Saccharomyces cerevisiae is an attractive host for this purpose as it has been extensively engineered for production of various fuels and chemicals. Many of the target molecules are derived from the central metabolite and molecular building block, acetyl-CoA. To date, it has been difficult to engineer S. cerevisiae to continuously convert sugars present in biomass-based feedstocks to acetyl-CoA derived products due to intrinsic physiological constraints-in respiring cells, the precursor pyruvate is directed away from the endogenous cytosolic acetyl-CoA biosynthesis pathway towards the mitochondria, and in fermenting cells pyruvate is directed towards the byproduct ethanol. In this study we incorporated an alternative mode of acetyl-CoA biosynthesis mediated by ATP citrate lyase (ACL) that may obviate such constraints. RESULTS: We characterized the activity of several heterologously expressed ACLs in crude cell lysates, and found that ACL from Aspergillus nidulans demonstrated the highest activity. We employed a push/pull strategy to shunt citrate towards ACL by deletion of the mitochondrial NAD(+)-dependent isocitrate dehydrogenase (IDH1) and engineering higher flux through the upper mevalonate pathway. We demonstrated that combining the two modifications increases accumulation of mevalonate pathway intermediates, and that both modifications are required to substantially increase production. Finally, we incorporated a block strategy by replacing the native ERG12 (mevalonate kinase) promoter with the copper-repressible CTR3 promoter to maximize accumulation of the commercially important molecule mevalonate. CONCLUSION: By combining the push/pull/block strategies, we significantly improved mevalonate production. We anticipate that this strategy can be used to improve the efficiency with which industrial strains of S. cerevisiae convert feedstocks to acetyl-CoA derived fuels and chemicals.

DLK initiates a transcriptional program that couples apoptotic and regenerative responses to axonal injury.

The cell intrinsic factors that determine whether a neuron regenerates or undergoes apoptosis in response to axonal injury are not well defined. Here we show that the mixed-lineage dual leucine zipper kinase (DLK) is an essential upstream mediator of both of these divergent outcomes in the same cell type. Optic nerve crush injury leads to rapid elevation of DLK protein, first in the axons of retinal ganglion cells (RGCs) and then in their cell bodies. DLK is required for the majority of gene expression changes in RGCs initiated by injury, including induction of both proapoptotic and regeneration-associated genes. Deletion of DLK in retina results in robust and sustained protection of RGCs from degeneration after optic nerve injury. Despite this improved survival, the number of axons that regrow beyond the injury site is substantially reduced, even when the tumor suppressor phosphatase and tensin homolog (PTEN) is deleted to enhance intrinsic growth potential. These findings demonstrate that these seemingly contradictory responses to injury are mechanistically coupled through a DLK-based damage detection mechanism.

Multicenter evaluation of the utilization of endoscopic ultrasound.

BACKGROUND AND AIM: There are currently no data regarding the number and type of endoscopic ultrasound (EUS) procedures being carried out in the USA. The aims of the present study are to: (i) estimate the annual number of EUS procedures being carried out in a nationwide database; (ii) describe the indications and types of EUS carried out; and (iii) examine short-term trends in volume. METHODS: Retrospective analysis from the Clinical Outcomes Research Initiative (CORI) of EUS procedures carried out on patients >18 years of age from 1 January 2010 through 31 December 2013. RESULTS: EUS cases (n = 7614) were carried out by 68 endoscopists at 18 sites over the study period, representing 1.7% of the total number of endoscopic procedures. The most common indications were evaluation of a pancreatic mass (14.7%), diagnostic sampling with fine-needle aspiration (14.1%), and evaluation of a pancreatic cyst (14.0%). The number of EUS examinations and cases undergoing same-day endoscopic retrograde cholangiopancreatography (ERCP) increased over the study period (P < 0.0001). Use of general anesthesia or deep sedation increased markedly from 37.8% to 82.8% of procedures (P < 0.0001). CONCLUSIONS: This is the largest survey of EUS practice in the USA. Evaluation of the pancreas accounts for approximately 40% of the indications for EUS. Use of EUS increased over the study period, and the proportion carried out with deep sedation or general anesthesia also increased. These data may have implications regarding the number of endosonographers who should be trained, as well as cost issues pertaining to increasing use of anesthesia providers and same-day ERCP.

Genetic analysis reveals that amyloid precursor protein and death receptor 6 function in the same pathway to control axonal pruning independent of ß-secretase.

In the developing brain, initial neuronal projections are formed through extensive growth and branching of developing axons, but many branches are later pruned to sculpt the mature pattern of connections. Despite its widespread occurrence, the mechanisms controlling pruning remain incompletely characterized. Based on pharmacological and biochemical analysis in vitro and initial genetic analysis in vivo, prior studies implicated a pathway involving binding of the Amyloid Precursor Protein (APP) to Death Receptor 6 (DR6) and activation of a downstream caspase cascade in axonal pruning. Here, we further test their involvement in pruning in vivo and their mechanism of action through extensive genetic and biochemical analysis. Genetic deletion of DR6 was previously shown to impair pruning of retinal axons in vivo. We show that genetic deletion of APP similarly impairs pruning of retinal axons in vivo and provide evidence that APP and DR6 act cell autonomously and in the same pathway to control pruning. Prior analysis had suggested that ß-secretase cleavage of APP and binding of an N-terminal fragment of APP to DR6 is required for their actions, but further genetic and biochemical analysis reveals that ß-secretase activity is not required and that high-affinity binding to DR6 requires a more C-terminal portion of the APP ectodomain. These results provide direct support for the model that APP and DR6 function cell autonomously and in the same pathway to control pruning in vivo and raise the possibility of alternate mechanisms for how APP and DR6 control pruning.

Devices for the endoscopic treatment of hemorrhoids.

Multiple endoscopic methods are available to treat symptomatic internal hemorrhoids. Because of its low cost, ease of use, low rate of adverse events, and relative effectiveness, RBL is currently the most widely used technique.