Standardized indolent systemic mastocytosis evaluations across a health care system: implications for screening accuracy.

ABSTRACT: Timely diagnosis of systemic mastocytosis (SM) remains challenging because of care heterogeneity. We implemented a standardized approach for SM screening and diagnosis using a novel health care system-wide international screening registry. A retrospective analysis assessed rates of SM, cutaneous mastocytosis (CM), and molecular diagnoses before and 2 years after care standardization. The accuracy of individual and combined SM screening tests, basal serum tryptase (BST) ≥11.5 and ≥20.0 ng/mL, REMA ≥2, monomorphic maculopapular CM (MPCM), and elevated BST based upon tryptase genotype, was analyzed. Tryptase genotyping and high-sensitivity KIT p.D816V testing increased substantially 2 years after care standardization. SM diagnoses doubled from 47 to 94, and KIT p.D816V molecular diagnoses increased from 24 to 79. Mean BST and KIT p.D816V variant allele frequency values were significantly lower in patients diagnosed after standardization. Hereditary-alpha tryptasemia prevalence was increased in SM before care standardization (4/30 [13.3%]) but reflected the general population prevalence 2 years later at (5/76 [6.6%]). Elevated BST based upon genotype and BST ≥11.5 ng/mL had the highest sensitivities at 84.2% and 88.3%, respectively. The presence of monomorphic MPCM, elevated BST based upon tryptase genotype, and the combination of REMA ≥2 with elevated BST based upon tryptase genotype had specificities >90%. BST >20.0 ng/mL had low sensitivity and specificity and was not required to establish any indolent SM (ISM) diagnosis. Care standardization increased SM diagnosis rates, particularly in patients with low BSTs. Stratifying BST based upon genotype had the best overall sensitivity and specificity of any ISM screening test and improved the REMA score specificity.

Systematic synthesis and identification of monolignol pathway metabolites.

Monolignol serves as the building blocks to constitute lignin, the second abundant polymer on Earth. Despite two decades of diligent efforts, complete identification of all metabolites in the currently proposed monolignol biosynthesis pathway has proven elusive. This limitation also hampers their potential application. One of the primary obstacles is the challenge of assembling a collection of all molecules, because many are commercially unavailable or prohibitively costly. In this study, we established systematic pipelines to synthesize all 24 molecules through the conversions between functional groups on a core structure followed by the application to other core structures. We successfully identified all of them in Populus trichocarpa and Eucalyptus grandis, two representative species respectively from malpighiales and myrtales in angiosperms. Knowledge about monolignol metabolite chemosynthesis and identification will form the foundation for future studies.

Traumatic terson syndrome with a peculiar mass lesion and tractional retinal detachment: a case report.

BACKGROUND: To report a case with bilateral Terson syndrome presented with a unique mushroom-like mass lesion on the optic disc along with proliferative vitreoretinopathy and tractional retinal detachment. CASE PRESENTATION: A 33-year-old man was injured during a traffic accident and had diffuse brain swelling and intraocular hemorrhage. Poor vision in both eyes was noted after the patient regained consciousness. B-scan ultrasonography showed extensive vitreous opacity with a posterior vitreous detachment and without obvious retinal detachment. Vitrectomy was performed in both eyes five months after the accident. After clearing up the vitreous opacity, a peculiar pigmented mushroom-like mass lesion was noted in the posterior pole and had severe adhesion to the underneath optic disc. Extensive multilayered peripapillary epiretinal membrane was found covering the posterior pole and led to tractional retinal detachment around the macula. The mass was presumed to be an organized vitreous hemorrhage originated from the optic disc. The extensive and adherent epiretinal membrane together with the mass lesion were removed as much as possible and silicon oil was injected for tamponade. However, in the right eye, the retina redetached under silicon oil, whereas in the left eye, his vision improved to 20/100. CONCLUSIONS: Terson syndrome usually has a favorable prognosis but may be complicated by proliferative vitreoretinopathy and tractional retinal detachment. Careful monitoring is warranted and early vitrectomy should be considered in cases suspecting additional pathologies.

All-optical switching of magnetization in atomically thin CrI3.

Control of magnetism has attracted interest in achieving low-power and high-speed applications such as magnetic data storage and spintronic devices. Two-dimensional magnets allow for control of magnetic properties using the electric field, electrostatic doping and strain. In two-dimensional atomically thin magnets, a non-volatile all-optical method would offer the distinct advantage of switching magnetic states without application of an external field. Here, we demonstrate such all-optical magnetization switching in the atomically thin ferromagnetic semiconductor, CrI3, triggered by circularly polarized light pulses. The magnetization switching behaviour strongly depends on the exciting photon energy and polarization, in correspondence with excitonic transitions in CrI3, indicating that the switching process is related to spin angular momentum transfer from photoexcited carriers to local magnetic moments. Such an all-optical magnetization switching should allow for further exploration of magneto-optical interactions and open up applications in high-speed and low-power spintronic devices.

Antenatal Corticosteroid Exposure is Associated with Childhood Mental Disorders in Late Preterm and Term Infants.

OBJECTIVES: To study the association between antenatal corticosteroids treatment and childhood mental disorders in infants born at different gestational ages, and to investigate the effect of different administration timing. STUDY DESIGN: This population-based cohort study used data from the Taiwan National Health Insurance Research Database. All singleton live births born between 2004 and 2010 were enrolled and followed up for at least 6 years. The primary outcome was any childhood mental disorder. Secondary outcomes included 7 specific subgroups of mental disorders. RESULTS: A total of 1 163 443 singleton infants were included in the analysis, and 16 847 (1.45%) infants were exposed to antenatal corticosteroid treatment. Children exposed to antenatal corticosteroids were found to have a higher risk of developing childhood mental disorders in the entire cohort (hazard ratio [HR], 1.13; 95% CI, 1.08-1.18), the term group (HR, 1.11; 95% CI, 1.05-1.16), and the late-preterm group (HR, 1.15; 95% CI, 1.06-1.25). The administration of corticosteroids in the early stage of pregnancy (<28 weeks of gestation) significantly increased the risk of childhood mental disorders (HR, 1.22; 95% CI, 1.14-1.31). CONCLUSIONS: Exposure to antenatal corticosteroid treatment increases the cumulative risk of childhood mental disorders and attention deficit hyperactivity disorders, both in term and late preterm infants. The administration of corticosteroids in the early stage of pregnancy tends to increase the risk of mental disorders.

Prognostic value of neutrophil-lymphocyte ratio in out-of-hospital cardiac arrest patients receiving targeted temperature management: An observational cohort study.

BACKGROUND: Out-hospital cardiac arrest (OHCA) is a major cause of mortality and morbidity worldwide. The magnitude of the post-resuscitation inflammatory response is closely related to the severity of the circulatory dysfunction. Currently, targeted temperature management (TTM) has become an essential part of the post-resuscitation care for unconscious OHCA survivors. Some novel prognostic inflammatory markers may help predict outcomes of OHCA patients after TTM. METHODS: A retrospective observational cohort study of 65 OHCA patients treated with TTM was conducted in a tertiary hospital in Taiwan. The primary outcome measure was in-hospital mortality. Baseline and post-TTM neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte (PLR), and the systemic immune inflammation index (SII) were identified as potential predictors. RESULTS: These patients had a mean age of 62.2 ± 17.0 years. Among the total sample, 53.8% had an initial shockable rhythm and 61.5% had a presumed cardiac etiology. The median resuscitation duration was 20 min (IQR 13.5-28.5) and 60% received subsequent percutaneous coronary intervention. The mean baseline NLR, PLR and SII were 7.5 ± 16.7, 118 ± 207, 1395 ± 3004, and the mean post-TTM NLR, PLR and SII were 15.0 ± 11.6, 206 ± 124, 2369 ± 2569, respectively. Using multiple logistic regression analysis, post-TTM NLR was one of the independent factors which predicted in-hospital mortality (adjusted odds ratio (aOR): 1.249, 95% confidence interval (CI): 1.040-1.501, p = 0.017). CONCLUSION: Post-TTM NLR is a predictor of in-hospital mortality in OHCA patients who underwent TTM.

Controlling Andreev Bound States with the Magnetic Vector Potential.

Tunneling spectroscopy measurements are often used to probe the energy spectrum of Andreev bound states (ABSs) in semiconductor-superconductor hybrids. Recently, this spectroscopy technique has been incorporated into planar Josephson junctions (JJs) formed in two-dimensional electron gases, a potential platform to engineer phase-controlled topological superconductivity. Here, we perform ABS spectroscopy at the two ends of planar JJs and study the effects of the magnetic vector potential on the ABS spectrum. We show that the local superconducting phase difference arising from the vector potential is equal in magnitude and opposite in sign at the two ends, in agreement with a model that assumes localized ABSs near the tunnel barriers. Complemented with microscopic simulations, our experiments demonstrate that the local phase difference can be used to estimate the relative position of localized ABSs separated by a few hundred nanometers.

A Novel Probiotic-Based Oral Vaccine against SARS-CoV-2 Omicron Variant B.1.1.529.

COVID-19 pandemic, caused by the SARS-CoV-2 virus, is still affecting the entire world via the rapid emergence of new contagious variants. Vaccination remains the most effective prevention strategy for viral infection, yet not all countries have sufficient access to vaccines due to limitations in manufacturing and transportation. Thus, there is an urgent need to develop an easy-to-use, safe, and low-cost vaccination approach. Genetically modified microorganisms, especially probiotics, are now commonly recognized as attractive vehicles for delivering bioactive molecules via oral and mucosal routes. In this study, Lactobacillus casei has been selected as the oral vaccine candidate based on its' natural immunoadjuvant properties and the ability to resist acidic gastric environment, to express antigens of SARS-CoV-2 Omicron variant B.1.1.529 with B-cell and T-cell epitopes. This newly developed vaccine, OMGVac, was shown to elicit a robust IgG systemic immune response against the spike protein of Omicron variant B.1.1.529 in Golden Syrian hamsters. No adverse effects were found throughout this study, and the overall safety was evaluated in terms of physiological and histopathological examinations of different organs harvested. In addition, this study illustrated the use of the recombinant probiotic as a live delivery vector in the initiation of systemic immunity, which shed light on the future development of next-generation vaccines to combat emerging infectious diseases.

A novel synthetic-genetic-array-based yeast one-hybrid system for high discovery rate and short processing time.

Eukaryotic gene expression is often tightly regulated by interactions between transcription factors (TFs) and their DNA cis targets. Yeast one-hybrid (Y1H) is one of the most extensively used methods to discover these interactions. We developed a high-throughput meiosis-directed yeast one-hybrid system using the Magic Markers of the synthetic genetic array analysis. The system has a transcription factor-DNA interaction discovery rate twice as high as the conventional diploid-mating approach and a processing time nearly one-tenth of the haploid-transformation method. The system also offers the highest accuracy in identifying TF-DNA interactions that can be authenticated in vivo by chromatin immunoprecipitation. With these unique features, this meiosis-directed Y1H system is particularly suited for constructing novel and comprehensive genome-scale gene regulatory networks for various organisms.

A Simple Risk Score for Predicting Neurologic Outcome in Out-of-Hospital Cardiac Arrest Patients After Targeted Temperature Management.

OBJECTIVES: Although several risk factors for outcomes of out-of-hospital cardiac arrest patients have been identified, the cumulative risk of their combinations is not thoroughly clear, especially after targeted temperature management. Therefore, we aimed to develop a risk score to evaluate individual out-of-hospital cardiac arrest patient risk at early admission after targeted temperature management regarding poor neurologic status at discharge. DESIGN: Retrospective observational cohort study. SETTING: Two large academic medical networks in the United States. PATIENTS: Out-of-hospital cardiac arrest survivors treated with targeted temperature management with age of 18 years old or older. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Based on the odds ratios, five identified variables (initial nonShockable rhythm, Leucocyte count < 4 or > 12 K/µL after targeted temperature management, total Adrenalin [epinephrine] ≥ 5 mg, lack of oNlooker cardiopulmonary resuscitation, and Time duration of resuscitation ≥ 20 min) were assigned weighted points. The sum of the points was the total risk score known as the SLANT score (range 0-21 points) for each patient. Based on our risk prediction scores, patients were divided into three risk categories as moderate-risk group (0-7), high-risk group (8-14), and very high-risk group (15-21). Both the ability of our risk score to predict the rates of poor neurologic outcomes at discharge and in-hospital mortality were significant under the Cochran-Armitage trend test (p < 0.001 and p < 0.001, respectively). CONCLUSIONS: The risk of poor neurologic outcomes and in-hospital mortality of out-of-hospital cardiac arrest survivors after targeted temperature management is easily assessed using a risk score model derived using the readily available information. Its clinical utility needed further investigation.

Postvitrectomy endophthalmitis caused by Morganella morganii: a case report and literature review.

BACKGROUND: Postvitrectomy endophthalmitis is a rare and serious complication following vitreoretinal surgeries. Morganella morganii, an emerging gram-negative, facultative anaerobic rod, is related to severe nosocomial infections in various organs and thus has gained importance in recent decades. Morganella morganii infection following intraocular surgery is rarely reported. CASE PRESENTATION: We report an immunocompetent patient with Morganella morganii-related endophthalmitis after vitrectomy for retinal detachment who presented with hand motion visual acuity, hypopyon and a unique retrolental exudative membrane. Initially, the patient was unresponsive to empirical intravitreal ceftazidime and vancomycin but recovered with vision preservation (20/63) after surgical removal of the membrane and silicone oil tamponade. CONCLUSIONS: Morganella morganii intraocular infection is often devastating, likely due to its high multidrug-resistance rate via intrinsic ß-lactamase production, multiple acquired traits related to additional genetic mechanisms, and fimbrial adhesion, urease production, and type III secretion system-associated biofilm formation. The above characteristics of M. morganii may lead to an inadequate response to empirical intravitreal antibiotics, and early surgical intervention should be considered.

Delayed-onset radiculopathy caused by a retropulsed bone fragment after percutaneous kyphoplasty: report of four cases and literature review.

BACKGROUND: Vertebral compression fractures caused by osteoporosis are common in elderly patients and are often encountered by clinical physicians. Percutaneous balloon kyphoplasty (PKP) is widely accepted as a minimally invasive procedure for effectively relieving pain and correcting deformities, but complications may occur. Radiculopathy with a delayed onset caused by a retropulsed bone fragment has not been adequately described in the literature. Thus, this article presents a case report of four cases of retropulsed bone fragment-related radiculopathy after PKP. CASE PRESENTATION: In this article, we reported that four out of 251 patients developed radiculopathy after PKP between January 2012 and January 2019 despite experiencing substantial improvements in back pain. All patients with radiculopathy were female and diagnosed with osteoporosis, and their ages ranged from 68 to 89 years. Radiculopathy occurred from 2 to 16 weeks after PKP. All four patients underwent another operation (posterior decompression and instrumentation). Three patients recovered completely, and one died of postoperative intracranial haemorrhage. A detailed imaging study with pre- and postoperative magnetic resonance imaging (MRI) revealed that retropulsed bone fragments that impinged on the corresponding root after PKP were responsible for this complication, and all four patients developed a disrupted posterior vertebral rim preoperatively. No leakage of cement or pedicle track violations were observed. CONCLUSION: Although PKP is a safe and effective treatment for painful osteoporotic vertebral compression fractures, a risk of catastrophic neurological injury remains. Radiculopathy with delayed onset caused by a retropulsed bone fragment after kyphoplasty is rare and challenging to treat, and the integrity of the posterior vertebral cortex should be carefully evaluated preoperatively to prevent this complication.

Large-scale data analysis for robotic yeast one-hybrid platforms and multi-disciplinary studies using GateMultiplex.

BACKGROUND: Yeast one-hybrid (Y1H) is a common technique for identifying DNA-protein interactions, and robotic platforms have been developed for high-throughput analyses to unravel the gene regulatory networks in many organisms. Use of these high-throughput techniques has led to the generation of increasingly large datasets, and several software packages have been developed to analyze such data. We previously established the currently most efficient Y1H system, meiosis-directed Y1H; however, the available software tools were not designed for processing the additional parameters suggested by meiosis-directed Y1H to avoid false positives and required programming skills for operation. RESULTS: We developed a new tool named GateMultiplex with high computing performance using C++. GateMultiplex incorporated a graphical user interface (GUI), which allows the operation without any programming skills. Flexible parameter options were designed for multiple experimental purposes to enable the application of GateMultiplex even beyond Y1H platforms. We further demonstrated the data analysis from other three fields using GateMultiplex, the identification of lead compounds in preclinical cancer drug discovery, the crop line selection in precision agriculture, and the ocean pollution detection from deep-sea fishery. CONCLUSIONS: The user-friendly GUI, fast C++ computing speed, flexible parameter setting, and applicability of GateMultiplex facilitate the feasibility of large-scale data analysis in life science fields.

InSbAs Two-Dimensional Electron Gases as a Platform for Topological Superconductivity.

Topological superconductivity can be engineered in semiconductors with strong spin-orbit interaction coupled to a superconductor. Experimental advances in this field have often been triggered by the development of new hybrid material systems. Among these, two-dimensional electron gases (2DEGs) are of particular interest due to their inherent design flexibility and scalability. Here, we discuss results on a 2D platform based on a ternary 2DEG (InSbAs) coupled to in situ grown aluminum. The spin-orbit coupling in these 2DEGs can be tuned with the As concentration, reaching values up to 400 meV Å, thus exceeding typical values measured in its binary constituents. In addition to a large Landé g-factor of ∼55 (comparable to that of InSb), we show that the clean superconductor-semiconductor interface leads to a hard induced superconducting gap. Using this new platform, we demonstrate the basic operation of phase-controllable Josephson junctions, superconducting islands, and quasi-1D systems, prototypical device geometries used to study Majorana zero modes.

Application of Convolutional Neural Network for Fingerprint-Based Prediction of Gender, Finger Position, and Height.

Fingerprints are the most common personal identification feature and key evidence for crime scene investigators. The prediction of fingerprints features include gender, height range (tall or short), left or right hand, and finger position can effectively narrow down the list of suspects, increase the speed of comparison, and greatly improve the effectiveness of criminal investigations. In this study, we used three commonly used CNNs (VGG16, Inception-v3, and Resnet50) to perform biometric prediction on 1000 samples, and the results showed that VGG16 achieved the highest accuracy in identifying gender (79.2%), left- and right-hand fingerprints (94.4%), finger position (84.8%), and height range (69.8%, using the ring finger of male participants). In addition, we visualized the CNN classification basis by the Grad-CAM technique and compared the results with those predicted by experts and found that the CNN model outperformed experts in terms of classification accuracy and speed, and provided good reference for fingerprints that were difficult to determine manually.

Secular Trends in the Incidence, Prevalence, and Medications for Epilepsy from 2007 to 2015 in Taiwan: A Nationwide Population-Based Study.

BACKGROUND: Patients with epilepsy have a higher mortality rate than the general population. Up-to-date estimates of epilepsy incidence, prevalence, and medication use are critical to assist policymaking. METHODS: Using the National Taiwan Insurance Research Database, the standardized incidence and prevalence of epilepsy were estimated in each calendar year from 2007 to 2015. We used the incident cases of epilepsy to analyze the change in prescribing patterns from 2007 to 2015. Joinpoint regression was used to estimate secular trends. RESULTS: From 2007 to 2015, the age- and sex-standardized incidence decreased from 0.72 (95% confidence interval [CI] 0.70-0.73) to 0.54 (95% CI 0.53-0.55) per 1,000 person-years, giving an annual percentage change (APC) of -2.73 (p < 0.05). Among patients younger than 20 years, the incidence did not change significantly. The age- and sex-standardized prevalence decreased from 6.94 (95% CI 6.90-6.98) to 6.86 (95% CI, 6.82-6.89) per 1,000 people, giving an APC of -0.31 (p < 0.05). However, the prevalence increased in the 35- to 49- and 50- to 64-year age-groups. The most common first-line anticonvulsant was phenytoin in 2007 and valproate in 2015. The use of levetiracetam, clobazam, and valproate increased during the study period, with APCs of 25.48% (95% CI 19.97-31.24), 6.41 (3.09-9.85), and 2.83 (1.51-4.16), respectively. The use of carbamazepine, phenytoin, and topiramate decreased; the APCs were -23.86% (95% CI -25.25 to -22.44), -6.61 (-8.40 to -4.79), and -4.29% (-7.87 to -0.57), respectively. CONCLUSIONS: The overall prevalence and incidence of epilepsy decreased slightly from 2007 to 2015. The prescribed first-line anticonvulsant also changed over time.

Predictors of Successful Weaning from Noninvasive Ventilation in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Single-Center Retrospective Cohort Study.

PURPOSE: Noninvasive ventilation (NIV) is often required for patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD), and it can significantly reduce the need for endotracheal intubation. Currently, there is no standard method for predicting successful weaning from NIV. Therefore, we aimed to evaluate whether a weaning index can predict NIV outcomes of patients with AECOPD. METHODS: This study was conducted at a single academic public hospital in northern Taiwan from February 2019 to January 2021. Patients with AECOPD admitted to the hospital with respiratory failure who were treated with NIV were included in the study. Univariate and multivariate logistic regression analyses were used to identify independent predictors of successful weaning from NIV. Receiver operating characteristic curve methodology was used to assess the predictive capacity. RESULTS: A total of 85 patients were enrolled, 65.9% of whom were successfully weaned from NIV. The patients had a mean age of 75.8 years and were mostly men (89.4%). The rapid shallow breathing index (RSBI) (P < 0.001), maximum inspiratory pressure (P = 0.014), and maximum expiratory pressure (P = 0.004) of the successful group were significant while preparing to wean. The area under the receiver operating characteristic curve for the RSBI was 0.804, which was considered excellent discrimination. CONCLUSION: The RSBI predicted successful weaning from NIV in patients with AECOPD with hypercapnic respiratory failure. This index may be useful for selecting patients with AECOPD that are suitable for NIV weaning.

Unilateral Vision Loss After Hyaluronic Acid Injection: A Case Report.

ABSTRACT: Vascular occlusion causing vision loss is a rare yet one of the most devastating complications of facial esthetic fillers. In this article, we present a case of unilateral blindness and superficial skin necrosis in a 31-year-old woman after the injection of hyaluronic acid for esthetic purposes. The delicate ocular fundal findings of ophthalmic artery occlusion were demonstrated by ophthalmoscopy, optical coherence tomography, and fluorescein angiography. Magnetic resonance imaging also showed subsequent ischemic changes in the optic nerve and posterior scleral wall after ophthalmic artery occlusion. Despite management including intraocular pressure-lowering agents, globe massage, and anticoagulation with acetylsalicylic acid and hyperbaric oxygen therapy, her final vision was not restored. Given the lack of effective treatments, this report depicts the comprehensive ocular fundal findings of an ophthalmic artery occlusion after esthetic hyaluronic acid filler injection, and highlights the importance of a preventive approach to avoid such catastrophic complications.

Hook plate with or without coracoclavicular ligament augmentation in the treatment of acute acromioclavicular separation.

BACKGROUND: Acromioclavicular (AC) separation can be treated with the use of a hook plate. Some studies have reported that coracoclavicular (CC) ligament augmentation is necessary to reduce the complications of hook plate fixation, whereas others recommend hook plate fixation alone without augmentation. The aim of this study was to compare the results and complications between these two groups. METHODS: This was an observational case-control study. Patients with acute (less than 2 weeks) Rockwood type V AC separation were treated with a hook plate at our hospital. A total of 105 cases received hook plate fixation with CC ligament augmentation (group I), and 112 cases received hook plate fixation without augmentation (group II). Constant-Murley scores were used to evaluate the function before and after implant removal, and radiographs were taken to evaluate the complications. The results and complications were compared between groups. RESULTS: Before removal, the Constant-Murley score was significantly higher in group I (mean, 50.1) than in group II (mean, 42.6) (p = 0.004); however, there was no significant difference between groups at 3 and 6 months after removal. The incidence of significant acromion osteolysis was higher in group II (65/112) than in group I (25/105). Before removal, the patients with significant acromion osteolysis had worse Constant-Murley scores than those of the patients without osteolysis in both groups. The incidence of peri-implant fracture of the hook plate was higher in group II (8/112) than in group I (1/105). CONCLUSION: The patients without CC ligament augmentation had worse functional results before hook plate removal, a higher incidence of radiographic acromion osteolysis, and a higher incidence of peri-implant fractures than those patients with CC ligament augmentation. Therefore, CC ligament augmentation is highly recommended to improve short-term outcomes and decrease complications for Rockwood type V AC separation treated by hook plate.

Crystal Structure of PigA: A Prolyl Thioester-Oxidizing Enzyme in Prodigiosin Biosynthesis.

Prodigiosin is an intensely red pigment comprising three pyrroles. The biosynthetic pathway includes a two-step proline oxidation catalyzed by phosphatidylinositol N-acetylglucosaminyltransferase subunit A (PigA), with flavin adenine dinucleotide (FAD) as its cofactor. The enzyme is crystallized in the apo form and in complex with FAD and proline. As an acyl coenzyme A dehydrogenase (ACAD) family member, the protein folds into a ß-sheet flanked by two α-helical domains. PigA forms a tetramer, which is consistent with analytical ultracentrifugation results. FAD binds to PigA in a similar way to that in the other enzymes of the ACAD family. The variable conformations of loop ß4-ß5 and helix αG correlate well with the structural flexibility required for substrate entrance to the Re side of FAD. Modeling with PigG, the acyl carrier protein, suggests a reasonable mode of interaction with PigA. The structure helps to explain the proline oxidation mechanism, in which Glu244 plays a central role by abstracting the substrate protons. It also reveals a plausible pocket for oxygen binding to the Si side of FAD.