Synthetic group A streptogramin antibiotics that overcome Vat resistance.

Natural products serve as chemical blueprints for most antibiotics in clinical use. The evolutionary process by which these molecules arise is inherently accompanied by the co-evolution of resistance mechanisms that shorten the clinical lifetime of any given class of antibiotics1. Virginiamycin acetyltransferase (Vat) enzymes are resistance proteins that provide protection against streptogramins2, potent antibiotics against Gram-positive bacteria that inhibit the bacterial ribosome3. Owing to the challenge of selectively modifying the chemically complex, 23-membered macrocyclic scaffold of group A streptogramins, analogues that overcome the resistance conferred by Vat enzymes have not been previously developed2. Here we report the design, synthesis, and antibacterial evaluation of group A streptogramin antibiotics with extensive structural variability. Using cryo-electron microscopy and forcefield-based refinement, we characterize the binding of eight analogues to the bacterial ribosome at high resolution, revealing binding interactions that extend into the peptidyl tRNA-binding site and towards synergistic binders that occupy the nascent peptide exit tunnel. One of these analogues has excellent activity against several streptogramin-resistant strains of Staphylococcus aureus, exhibits decreased rates of acetylation in vitro, and is effective at lowering bacterial load in a mouse model of infection. Our results demonstrate that the combination of rational design and modular chemical synthesis can revitalize classes of antibiotics that are limited by naturally arising resistance mechanisms.

Standard Adult Gastric Emptying Scintigraphy Criteria Is Applicable for Partial Meal Ingestion.

BACKGROUND/AIMS: Gastric emptying scintigraphy is commonly performed to assess for dysmotility. A standardized meal with associated threshold criteria was established in 2000 to enable robust interpretation. However, no guidance is available to interpret results when patients do not ingest the entire meal. The purpose of this study is to determine the continued appropriateness of the threshold criteria in contemporary clinical practice and its relevance for partially ingested meals. METHODS: This retrospective study analyzed patients (n = 1365 total) who underwent solid-phase gastric emptying scintigraphy at an academic medical center. Patients were stratified based on their completion of the standard meal. Patients were further stratified into normal and delayed gastric emptying cohorts based on the current criteria. Percent gastric retention values at 1, 2, 3, and 4 h were compared. RESULTS: Median (95% upper reference) normal gastric retention values for the complete standard meal were 64% (87%) at 1 h, 25% (60%) at 2 h, 13% (54%) at 3 h and 4% (9%) at 4 h. Consumption of at least 50% of the standard meal yielded similar retention; 53% (86%) at 1 h, 19% (58%) at 2 h, 6% (29%) at 3 h and 3% (10%) at 4 h. There was no significant age- or gender-specific differences using the current criteria, and no differences were observed based on diabetic status. Retention values matched well with the current criteria and validated with data-driven clustering. CONCLUSION: Adult normative standards for gastric emptying scintigraphy are appropriate for differentiating normal and delayed populations and can be applied to partial meals with at least 50% completion.

Shovel and Cut Technique: Beveled Vitrectomy Probes to Address Diabetic Tractional Retinal Detachments.

PURPOSE: To describe a surgical technique using the structural advantages of beveled tip cutters. METHODS: The introduction of beveled tips has been one of the few modifications that have been performed to vitrectomy probes since first described by Machemer in 1972. Shovel and cut technique uses this incredible modification to access tighter planes and remove broad diabetic membranes. DESCRIPTION OF TECHNIQUE: The shovel and cut technique can be used with any gauge probe to which the bevel tip is applied. The beveled tip of the cutter is used in a shovel manner to create a tissue plane between the diabetic plaque and the retina. As the beveled tip of the cutter moves parallel to the underlying retina, scar tissue naturally feeds into the cutting port where it is cut and aspirated with low flow rates. CONCLUSION: Shovel and cut technique takes advantage of beveled tip technological innovation to allow easy access and tissue dissection of the most difficult plaques in diabetic membranes. This technique allows us to remove these plaques in a safer, more controlled manner than previous described techniques.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY MORPHOLOGY AFTER RHEGMATOGENOUS RETINAL DETACHMENT REPAIR: ALIGN Post Hoc Analysis.

PURPOSE: To compare foveal avascular zone (FAZ) geometric indices using optical coherence tomography angiography (OCTA) in pneumatic retinopexy (PnR) versus pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment (RRD). FAZ morphology was assessed as a possible imaging feature of retinal displacement. METHODS: This ALIGN post hoc analysis included primary fovea-off RRDs that underwent successful PnR or PPV, and performed OCTA, and fundus autofluorescence at (FAF) 3 months postoperatively at St. Michael's Hospital, Toronto, Canada. FAZ area (mm 2 ), axial ratio, circularity, and roundness were measured, and FAF images were assessed for retinal displacement. RESULTS: Seventy-two patients were included, 78% (56/72) were male mean age was 60 ± 9 years, and 60% (43/72) were phakic. Sixty-five percent (47/72) and 35% (25/72) underwent PnR and PPV, respectively. The mean baseline logarithm of the minimum angle of resolution visual acuity was 1.49 ± 0.76. FAZ circularity was lower after PPV (0.629 ± 0.120) versus PnR (0.703 ± 0.122); P = 0.016. Sixty-six patients had gradable FAF images. Retinal displacement was present in 29% (19/66), 84.2% (16/19) of which had displacement in the macula. FAZ circularity was lower in eyes with displacement in the macula (0.613 ± 0.110) versus those without displacement (0.700 ± 0.124); P = 0.015. There was a moderate negative correlation between 12-month aniseikonia and FAZ circularity(r = -0.262; P = 0.041). CONCLUSION: FAZ circularity was lower after PPV and in eyes with retinal displacement in the macula. Circularity was negatively correlated with 12-month aniseikonia scores. FAZ circularity may be another imaging feature to consider postoperatively after RRD repair.

Retinal Microvascular Density and Perfusion during an Insulin-Induced Hypoglycemia Episode: A Warning Call.

Aim: To evaluate retinal vascular perfusion and density by optical coherence tomography angiography (OCTA) before, during, and after hypoglycemia in individuals with diabetes mellitus with or without diabetic retinopathy (DR). Methods: A focused clinical history was performed, followed by an ophthalmological examination to document retinopathy status. OCTA was performed at baseline, at hypoglycemia, and at glucose normalization. Eye tracking and eye alignment devices on the platform were used to obtain a macular thickness cube (512 × 128) and vascular perfusion and density protocols of 3 × 3 mm. Retinal vascular reactivity was analyzed with superficial plexus vascular perfusion and density protocols on OCTA. Results: Fifty-two participants encompassing 97 eyes fulfilled the eligibility criteria. Their mean age was 42.9 ± 15.1 years (range, 22 to 65), and 20 (38.2%) were men. We found a statistically significant difference in vascular perfusion and density when comparing all groups at baseline. The controls had higher vascular perfusion and density values than the cases. Vascular perfusion and density were significantly reduced in all groups during the hypoglycemia episode, except for vascular density in DR cases. Conclusion: Acute hypoglycemia significantly alters the retinal vascularity in DM patients with and without DR, suggesting that repeated episodes of acute hypoglycemia could exacerbate retinopathy in the long term.

The effect of latency on surgical performance and usability in a three-dimensional heads-up display visualization system for vitreoretinal surgery.

PURPOSE: Although latency has been cited as a disadvantage of the three-dimensional heads-up display (3D HUD) visualization system for vitreoretinal surgery, there have been no publications evaluating the effect of latency on surgical performance. METHODS: Thirty participants conducted two tasks (external suturing and inner limiting membrane peeling) on a 3D HUD at 4 levels of latency: 50 ms (ms), 68 ms, 92 ms, and 122 ms. The task completion time was measured and patients answered a subjective questionnaire on usability. RESULTS: No difference in completion times was found between different levels of latencies in either task. Regarding usability, significant decreases were found at 122 ms for both the suturing and peeling task overall, but for experienced HUD users, there was less of a decrease. CONCLUSION: This study is the first to evaluate the effect of latency on 3D HUD for vitreoretinal surgery. The levels of latency in the current models of 3D HUD are unlikely to contribute to a decrease in surgical performance and usability with current technologies which have a latency of 70 ms.

Two-Year Results of the Phase 3 Randomized Controlled Study of Abicipar in Neovascular Age-Related Macular Degeneration.

PURPOSE: To report the 2-year efficacy and safety of abicipar every 8 weeks and quarterly (after initial doses) compared with monthly ranibizumab in patients with treatment-naïve neovascular age-related macular degeneration (nAMD). DESIGN: Two multicenter, randomized, phase 3 clinical trials with identical protocols (CEDAR and SEQUOIA). Analyses used pooled trial data. PARTICIPANTS: The trials enrolled 1888 patients (1 eye/patient) with active choroidal neovascularization secondary to age-related macular degeneration and best-corrected visual acuity (BCVA) of 24 to 73 Early Treatment Diabetic Retinopathy Study letters. METHODS: At enrollment, patients were assigned to study eye treatment with abicipar 2 mg every 8 weeks after initial doses at baseline and weeks 4 and 8 (abicipar Q8, n = 630), abicipar 2 mg every 12 weeks after initial doses at baseline and weeks 4 and 12 (abicipar Q12, n = 628), or ranibizumab 0.5 mg every 4 weeks (ranibizumab Q4, n = 630). MAIN OUTCOME MEASURES: Efficacy measures included stable vision (<15-letter loss in BCVA from baseline) and change from baseline in BCVA and central retinal thickness (CRT). Safety measures included adverse events (AEs). RESULTS: For patients who completed the study, efficacy of abicipar after initial doses was maintained through week 104. At week 104, the proportion of patients with stable vision was 93.0% (396/426), 89.8% (379/422), and 94.4% (470/498); mean change in BCVA from baseline was +7.8 letters, +6.1 letters, and +8.5 letters, and mean change in CRT from baseline was -147 µm, -146 µm, and -142 µm in the abicipar Q8 (14 injections), abicipar Q12 (10 injections), and ranibizumab Q4 (25 injections) groups, respectively. The overall incidence of intraocular inflammation (IOI) AEs was 15.4%, 15.3%, and 0.3% from baseline through week 52 and 16.2%, 17.6%, and 1.3% from baseline through week 104 in the abicipar Q8, abicipar Q12, and ranibizumab Q4 groups, respectively. CONCLUSIONS: Two-year results show efficacy of abicipar Q8 and Q12 in nAMD. First onset of IOI events with abicipar was much reduced in the second year and comparable with ranibizumab (0.8% and 2.3% vs. 1.0%). The extended duration of effect of abicipar allows for quarterly dosing and reduced treatment burden.

Repeat Evaluation of Lung Shunt Fraction is Unnecessary: A Retrospective Observational Study of Successive Lung Shunt Fractions from Variable Arterial Distributions in Patients Undergoing Radioembolization of Primary and Secondary Liver Tumors.

PURPOSE: To evaluate whether the recalculation of lung shunt fraction (LSF) is necessary prior to next-stage or same lobe repeat radioembolization. MATERIALS AND METHODS: Retrospective chart review was performed for patients who underwent radioembolization between February 2008 and December 2018. Eighty of 312 patients had repeat mapping angiograms and LSF calculations. A total of 160 LSF calculations were made using planar imaging (155, [97%]) and single-photon emission computed tomography (5 [3%]) technetium-99m macroaggregated albumin hepatic arterial injection imaging. The mean patient age was 61.8 years ± 12.7; 69 (86%) patients had metastatic disease and 11 (14%) had hepatocellular carcinoma. RESULTS: Patients had a median LSF of 5% (interquartile range [IQR] 3%-9%) with a median absolute difference of 1.25 (IQR 0.65-3.4) and a median of 76 days (IQR 42.5-120 days) between repeat LSF calculations. There was a median change in LSF of 0.2% between mapping studies (P = .11). There was no statistical significance between the repeat LSFs regardless of the arterial distribution (P = .79) or between tumor types (P = .75). No patients exceeded lung dose limits using actual or predicted prescribed dose amounts. The actual median lung dose was 2.6 Gy (IQR 1.8-4.4 Gy, maximum = 20.5) for the first radioembolization and 2.0 Gy (IQR 1.3-3.7 Gy, maximum = 10.1) for the second radioembolization. CONCLUSIONS: No significant difference in LSF was identified between different time points and arterial distributions within the same patient undergoing repeat radioembolization. In patients who receive well under 30-Gy lung dose for the initial treatment and a 50-Gy cumulative lung dose, repeat radioembolization treatments in the same patient may not require a repeat LSF calculation.

Biocompatible Chemotherapy for Leukemia by Acid-Cleavable, PEGylated FTY720.

Targeting the inability of cancerous cells to adapt to metabolic stress is a promising alternative to conventional cancer chemotherapy. FTY720 (Gilenya), an FDA-approved drug for the treatment of multiple sclerosis, has recently been shown to inhibit cancer progression through the down-regulation of essential nutrient transport proteins, selectively starving cancer cells to death. However, the clinical use of FTY720 for cancer therapy is prohibited because of its capability of inducing immunosuppression (lymphopenia) and bradycardia when phosphorylated upon administration. A prodrug to specifically prevent phosphorylation during circulation, hence avoiding bradycardia and lymphopenia, was synthesized by capping its hydroxyl groups with polyethylene glycol (PEG) via an acid-cleavable ketal linkage. Improved aqueous solubility was also accomplished by PEGylation. The prodrug reduces to fully potent FTY720 upon cellular uptake and induces metabolic stress in cancer cells. Enhanced release of FTY720 at a mildly acidic endosomal pH and the ability to substantially down-regulate cell-surface nutrient transporter proteins in leukemia cells only by an acid-cleaved drug were confirmed. Importantly, the prodrug demonstrated nearly identical efficacy to FTY720 in an animal model of BCR-Abl-driven leukemia without inducing bradycardia or lymphopenia in vivo, highlighting its potential clinical value. The prodrug formulation of FTY720 demonstrates the utility of precisely engineering a drug to avoid undesirable effects by tackling specific molecular mechanisms as well as a financially favorable alternative to new drug development. A multitude of existing cancer therapeutics may be explored for prodrug formulation to avoid specific side effects and preserve or enhance therapeutic efficacy.

Efficacy and Safety of Abicipar in Neovascular Age-Related Macular Degeneration: 52-Week Results of Phase 3 Randomized Controlled Study.

PURPOSE: To compare the efficacy and safety of abicipar every 8 weeks and quarterly (after initial doses) versus ranibizumab every 4 weeks in treatment-naïve patients with neovascular age-related macular degeneration (AMD). DESIGN: Two randomized, multicenter, double-masked, parallel-group, active-controlled, phase 3 clinical trials (CEDAR, SEQUOIA) with identical protocols were conducted. Data from both trials were pooled for analysis. PARTICIPANTS: Patients with active choroidal neovascularization secondary to AMD and best-corrected visual acuity (BCVA) of 24-73 Early Treatment Diabetic Retinopathy Study letters in the study eye were enrolled. METHODS: Patients (n = 1888) were randomized in a 1:1:1 ratio to study eye treatment with abicipar 2 mg every 8 weeks after 3 initial doses at baseline and weeks 4 and 8 (Q8), abicipar 2 mg every 12 weeks after 3 initial doses at baseline and weeks 4 and 12 (Q12), or ranibizumab 0.5 mg every 4 weeks (Q4). MAIN OUTCOME MEASURES: The primary efficacy end point was proportion of patients with stable vision (defined as <15-letter loss in BCVA from baseline) in the study eye at week 52. Secondary end points included change from baseline in BCVA and central retinal thickness (CRT) at week 52. Safety measures included adverse events (AEs). RESULTS: The proportion of patients with stable vision at week 52 was 93.2%, 91.3%, and 95.8% in the abicipar Q8, abicipar Q12, and ranibizumab Q4 groups, respectively, with both abicipar Q8 and Q12 noninferior to ranibizumab Q4. Week 52 mean change from baseline in BCVA was 7.5, 6.4, and 8.4 letters and in CRT was -144, -145, and -144 µm in the abicipar Q8, abicipar Q12, and ranibizumab Q4 groups, respectively. Incidence of intraocular inflammation (IOI) AEs was 15.4%, 15.3%, and 0.3%, respectively. The IOI AEs were typically mild or moderate in severity and treated with topical corticosteroids; 62 of 192 patients (32.3%) received oral and/or injectable corticosteroids. CONCLUSIONS: Abicipar Q8 and Q12 were both noninferior to ranibizumab Q4 in the primary end point of stable vision at week 52. Intraocular inflammation was more frequent with abicipar. Quarterly and Q8 abicipar reduce nAMD disease and treatment burden compared with monthly treatment.

Utility of 18F-Fluciclovine PET/CT for Detecting Prostate Cancer Recurrence in Patients With Low (< 1 ng/mL) or Very Low (< 0.3 ng/mL) Prostate-Specific Antigen Levels.

OBJECTIVE. We reviewed a retrospective series of 126 18F-fluciclovine PET/CT studies of patients with biochemically recurrent prostate cancer at low (< 1 ng/mL) and very low (< 0.3 ng/mL) prostate-specific antigen (PSA) levels. CONCLUSION. The rate of PET/CT positivity was 33% (15/46) in patients with low PSA levels and 0% (0/17) in patients with very low PSA levels. Our results suggest that 18F-fluciclovine PET/CT can be helpful for localizing recurrence in patients with PSA levels between 0.3 and 1 ng/mL and that 18F-fluciclovine PET/CT is not recommended in patients with PSA levels less than 0.3 ng/mL.

ECTOPIC INNER FOVEAL LAYER CLASSIFICATION SCHEME PREDICTS VISUAL OUTCOMES AFTER EPIRETINAL MEMBRANE SURGERY.

PURPOSE: To evaluate the ectopic inner foveal layer (EIFL) staging scheme as a visual prognostic factor for patients undergoing epiretinal membrane (ERM) surgery. METHODS: Retrospective study of 88 pseudophakic patients with diagnosis of idiopathic ERM who underwent ERM surgery with a minimum follow-up of 12 months. Preoperative and postoperative EIFL staging was correlated with the final best-corrected visual acuity (BCVA). As a secondary outcome, evaluation of the proportion of patients achieving final best-corrected visual acuity ≥20/40 in each stage was assessed. RESULTS: Based on the EIFL staging scheme, of 88 pseudophakic eyes analyzed, 24 (27.4%) were diagnosed as Stage 2 ERM, 45 (51.1%) as Stage 3 ERM, and 19 (21.5%) as Stage 4 ERM preoperatively. At the final follow-up visit, 70.8% of eyes with Stage 2 showed an improvement in EIFL staging scheme, while 68% of eyes in Stage 3 and 4 remained the same. The final best-corrected visual acuity significantly improved with all EIFL stages (P = <0.05). However, earlier stages were associated with better visual outcomes both preoperatively and postoperatively (Stage 2 > Stage 3 > Stage 4 P < 0.001). Final best-corrected visual acuity ≥20/40 was reached in 91.7% of eyes with Stage 2, 42.3% with Stage 3, and 5.2% with Stage 4. CONCLUSION: The EIFL staging scheme is an easy, fast, and reproducible method to evaluate visual prognosis with ERM surgery. Surgery on Stage 2 ERM results in significantly better visual outcomes and a greater chance of reversibility in anatomical changes.

Same-Day Bilateral Intravitreal Anti-Vascular Endothelial Growth Factor Injections: Experience of a Large Canadian Retina Center.

OBJECTIVE: To evaluate the outcomes and complications of bilateral same-day intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections. METHODS: This is a single-center, retrospective study that included 524 eyes of 262 patients who received concomitant bilateral intravitreal anti-VEGF injections in 2016 at St. Michael's Hospital, Toronto. If any of the patients were receiving simultaneous bilateral injections on a regular basis prior to 2016, data pertaining to previous injections were also reviewed. Everyone received bevacizumab, ranibizumab, or aflibercept in an office setting. RESULTS: A total of 9,798 intravitreal anti-VEGF injections (4,899 bilateral injection sessions) were performed in 524 eyes of 262 patients. The average number of bilateral injection sessions per patient was 18.7 ± 14.1. Ranibizumab was the most commonly used anti-VEGF drug (83.8%). The incidence of endophthalmitis was 0.01%, and there were 2 episodes of acute intraocular inflammation among the 9,798 injections (0.02%). All 3 cases occurred after treatment with ranibizumab. There were 2 deaths (0.76%) due to nonvascular causes but no vascular related systemic adverse events were reported. CONCLUSIONS: Same-day bilateral intravitreal anti-VEGF injections present a low rate of complications and are well tolerated by patients. This safe practice may reduce the burden on the health-care system and on the patients.

Safety of Administering Furosemide During Nuclear Diuretic Renography in Patients With Sulfonamide Allergies.

OBJECTIVE: We reviewed the safety of nuclear diuretic renography with furosemide in patients with sulfonamide allergies. The electronic health record was used to uncover any drug effects reported within 30 days of diuretic renograms performed between January 2009 and December 2015. CONCLUSION: Eighty-three of 1103 (7.5%) diuretic renograms were performed on patients with sulfonamide allergies. Two instances of minor rash occurred. No serious reactions occurred. Furosemide is associated with an extremely low risk of minor reactions in patients with sulfonamide allergies.

Overexpression of calcium-activated potassium channels underlies cortical dysfunction in a model of PTEN-associated autism.

De novo phosphatase and tensin homolog on chromosome ten (PTEN) mutations are a cause of sporadic autism. How single-copy loss of PTEN alters neural function is not understood. Here we report that Pten haploinsufficiency increases the expression of small-conductance calcium-activated potassium channels. The resultant augmentation of this conductance increases the amplitude of the afterspike hyperpolarization, causing a decrease in intrinsic excitability. In vivo, this change in intrinsic excitability reduces evoked firing rates of cortical pyramidal neurons but does not alter receptive field tuning. The decreased in vivo firing rate is not associated with deficits in the dendritic integration of synaptic input or with changes in dendritic complexity. These findings identify calcium-activated potassium channelopathy as a cause of cortical dysfunction in the PTEN model of autism and provide potential molecular therapeutic targets.

Optical coherence tomography-based positioning regimen for macular hole surgery.

PURPOSE: To evaluate an optical coherence tomography (OCT)-based positioning regimen for patients undergoing macular hole surgery. METHOD: We reviewed the medical records of all patients in our practice who underwent macular hole repair, instituting a modified OCT-based positioning regimen from November 1, 2011 through July 31, 2013. The regimen consisted of prone positioning at the conclusion of surgery with daily OCT imaging until the hole was confirmed closed at which point positioning was halted. Clinical data that were collected and recorded included visual acuities, stage of hole, size of hole, chronicity, preoperative and postoperative OCT imaging, and length of follow-up. RESULTS: We identified 33 patients (35 eyes) with a mean baseline visual acuity of 20/220, a mean hole size of 465 µm. The mean final (postoperative) visual acuity was 20/135 with a mean follow-up of 7.7 months. Six patients (17%) in our study were diagnosed with myopic degeneration. Thirteen patients (37%) were found to have chronic (≥12 months) holes, and 19 (54%) were found to have large holes (>400 µm). Overall, 28 eyes (80%) had persistent closure of macular holes with an OCT-based positioning regimen. In the absence of high risk factors, such as myopic degeneration, chronic or large holes, the closure rate was 92%. In the presence of 2 or 3 of these risk factors, the closure rate was 85% and 74%, respectively. CONCLUSION: The presence of 2 or 3 high risk factors, such as myopic degeneration, chronic holes (≥12 months), or large holes (>400 µm) can compromise outcomes resulting in reopening after apparent early closure. Based on the presence of these risk factors, a modified postoperative positioning regimen can be used to obtain complete and persistent closure.