Human P450 CYP17A1: Control of Substrate Preference by Asparagine 202

CYP17A1 is a key steroidogenic enzyme known to conduct several distinct chemical transformations on multiple substrates. In its hydroxylase activity, this enzyme adds a hydroxyl group at the 17α position of both pregnenolone and progesterone at approximately equal rates. However, the subsequent 17,20 carbon–carbon scission reaction displays variable substrate specificity in the numerous CYP17A1 isozymes operating in vertebrates, manifesting as different Kd and kcat values when presented with 17α-hydroxypregnenlone (OHPREG) versus 17α-hydroxyprogesterone (OHPROG). Here we show that the identity of the residue at position 202 in human CYP17A1, thought to form a hydrogen bond with the A-ring alcohol substituent on the pregnene- nucleus, is a key driver of this enzyme’s native preference for OHPREG. Replacement of asparagine 202 with serine completely reverses the preference of CYP17A1, more than doubling the rate of turnover of the OHPROG to androstenedione reaction and substantially decreasing the rate of formation of dehydroepiandrosterone from OHPREG. In a series of resonance Raman experiments, it was observed that, in contrast with the case for the wild-type protein, in the mutant the 17α alcohol of OHPROG tends to form a H-bond with the proximal rather than terminal oxygen of the oxy–ferrous complex. When OHPREG was a substrate, the mutant enzyme was found to have a H-bonding interaction with the proximal oxygen that is substantially weaker than that of the wild type. These results demonstrate that a single-point mutation in the active site pocket of CYP17A1, even when far from the heme, has profound effects on steroidogenic selectivity in androgen biosynthesis

Accurate OH maser positions II. the Galactic Center region

We present high spatial resolution observations of ground-state OH masers, achieved using the Australia Telescope Compact Array (ATCA). These observations were conducted towards 171 pointing centres, where OH maser candidates were identified previously in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH) towards the Galactic Center region, between Galactic longitudes of $355^{\circ}$ and $5^{\circ}$ and Galactic latitudes of $-2^{\circ}$ and $+2^{\circ}$. We detect maser emission towards 162 target fields and suggest that 6 out of 9 non-detections are due to intrinsic variability. Due to the superior spatial resolution of the follow-up ATCA observations, we have identified 356 OH maser sites in the 162 of the target fields with maser detections. Almost half (161 of 356) of these maser sites have been detected for the first time in these observations. After comparing the positions of these 356 maser sites to the literature, we find that 269 (76\%) sites are associated with evolved stars (two of which are planetary nebulae), 31 (9\%) are associated with star formation, four are associated with supernova remnants and we were unable to determine the origin of the remaining 52 (15\%) sites. Unlike the pilot region (\citealt{Qie2016a}), the infrared colors of evolved star sites with symmetric maser profiles in the 1612 MHz transition do not show obvious differences compared with those of evolved star sites with asymmetric maser profiles.Comment: 24 pages, 12 figures, accepted by ApJ

Challenges and Solutions for Automotive OTA Testing

OTA (Over-The-Air) Testing is Essential for Developing Assisted and Autonomous Driving Systems in Vehicles, as It Plays a Crucial Role in the Localization, Perception, and Intelligent Driving Capabilities of ICVs (Intelligent Connected Vehicles). Automotive Antennas, Typically Much Smaller in Size Than the Vehicle itself and Can Be Located in Various Positions, Require Spherical Near-Field Measurement for OTA Testing. While There Are Established Standards for OTA Testing Methods and Uncertainties for Mobile Devices, Base Stations, and Satellite Components, There Are Still Many Challenges in the OTA Testing of Automotive Systems. These Challenges, specifically in SISO (Single Input Single Output) and MIMO (Multiple Input Multiple Output) Configurations, Are Discussed Along with Potential Solutions in This Article

Identification of Brush Species and Herbicide Effect Assessment in Southern Texas Using an Unoccupied Aerial System (UAS)

Cultivation and grazing since the mid-nineteenth century in Texas has caused dramatic changes in grassland vegetation. Among these changes is the encroachment of native and introduced brush species. The distribution and quantity of brush can affect livestock production and water holding capacity of soil. Still, at the same time, brush can improve carbon sequestration and enhance agritourism and real estate value. The accurate identification of brush species and their distribution over large land tracts are important in developing brush management plans which may include herbicide application decisions. Near-real-time imaging and analyses of brush using an Unoccupied Aerial System (UAS) is a powerful tool to achieve such tasks. The use of multispectral imagery collected by a UAS to estimate the efficacy of herbicide treatment on noxious brush has not been evaluated previously. There has been no previous comparison of band combinations and pixel- and object-based methods to determine the best methodology for discrimination and classification of noxious brush species with Random Forest (RF) classification. In this study, two rangelands in southern Texas with encroachment of huisache (Vachellia farnesianna [L.] Wight & Arn.) and honey mesquite (Prosopis glandulosa Torr. var. glandulosa) were studied. Two study sites were flown with an eBee X fixed-wing to collect UAS images with four bands (Green, Red, Red-Edge, and Near-infrared) and ground truth data points pre- and post-herbicide application to study the herbicide effect on brush. Post-herbicide data were collected one year after herbicide application. Pixel-based and object-based RF classifications were used to identify brush in orthomosaic images generated from UAS images. The classification had an overall accuracy in the range 83–96%, and object-based classification had better results than pixel-based classification since object-based classification had the highest overall accuracy in both sites at 96%. The UAS image was useful for assessing herbicide efficacy by calculating canopy change after herbicide treatment. Different effects of herbicides and application rates on brush defoliation were measured by comparing canopy change in herbicide treatment zones. UAS-derived multispectral imagery can be used to identify brush species in rangelands and aid in objectively assessing the herbicide effect on brush encroachment

Integrated Optical Coherence Tomography and Optical Coherence Microscopy Imaging of Ex Vivo Human Renal Tissues

available in PMC 2012 June 04Materials and Methods A total of 35 renal specimens from 19 patients, consisting of 12 normal tissues and 23 tumors (16 clear cell renal cell carcinomas, 5 papillary renal cell carcinomas and 2 oncocytomas) were imaged ex vivo after surgical resection. Optical coherence tomography and optical coherence microscopy images were compared to corresponding hematoxylin and eosin histology to identify characteristic features of normal and pathological renal tissues. Three pathologists blinded to histology evaluated the sensitivity and specificity of optical coherence microscopy images to differentiate normal from neoplastic renal tissues. Results Optical coherence tomography and optical coherence microscopy images of normal kidney revealed architectural features, including glomeruli, convoluted tubules, collecting tubules and loops of Henle. Each method of imaging renal tumors clearly demonstrated morphological changes and decreased imaging depth. Optical coherence tomography and microscopy features matched well with the corresponding histology. Three observers achieved 88%, 100% and 100% sensitivity, and 100%, 88% and 100% specificity, respectively, when evaluating normal vs neoplastic specimens using optical coherence microscopy images with substantial interobserver agreement (κ = 0.82, p <0.01). Conclusions Integrated optical coherence tomography and optical coherence microscopy imaging provides coregistered, multiscale images of renal pathology in real time without exogenous contrast medium or histological processing. High sensitivity and specificity were achieved using optical coherence microscopy to differentiate normal from neoplastic renal tissues, suggesting possible applications for guiding renal mass biopsy or evaluating surgical margins.National Institutes of Health (U.S.) (NIH Grants R01-CA75289-14)National Institutes of Health (U.S.) (NIH R01-HL095717-02)United States. Air Force Office of Scientific Research (FA9550-10-1-0063)United States. Air Force Office of Scientific Research (FA9550-10-1-0551

Computer-generated reminders and quality of pediatric HIV care in a resource-limited setting

OBJECTIVES: To evaluate the impact of clinician-targeted computer-generated reminders on compliance with HIV care guidelines in a resource-limited setting. METHODS: We conducted this randomized, controlled trial in an HIV referral clinic in Kenya caring for HIV-infected and HIV-exposed children (<14 years of age). For children randomly assigned to the intervention group, printed patient summaries containing computer-generated patient-specific reminders for overdue care recommendations were provided to the clinician at the time of the child's clinic visit. For children in the control group, clinicians received the summaries, but no computer-generated reminders. We compared differences between the intervention and control groups in completion of overdue tasks, including HIV testing, laboratory monitoring, initiating antiretroviral therapy, and making referrals. RESULTS: During the 5-month study period, 1611 patients (49% female, 70% HIV-infected) were eligible to receive at least 1 computer-generated reminder (ie, had an overdue clinical task). We observed a fourfold increase in the completion of overdue clinical tasks when reminders were availed to providers over the course of the study (68% intervention vs 18% control, P < .001). Orders also occurred earlier for the intervention group (77 days, SD 2.4 days) compared with the control group (104 days, SD 1.2 days) (P < .001). Response rates to reminders varied significantly by type of reminder and between clinicians. CONCLUSIONS: Clinician-targeted, computer-generated clinical reminders are associated with a significant increase in completion of overdue clinical tasks for HIV-infected and exposed children in a resource-limited setting

Sargasso Sea phosphorus biogeochemistry : an important role for dissolved organic phosphorus (DOP)

© The Authors, 2010. This article is distributed under the terms of the Creative Commons Attribution 3.0 License. The definitive version was published in Biogeosciences 7 (2010): 695-710, doi: 10.5194/bg-7-695-2010Inorganic phosphorus (SRP) concentrations in the subtropical North Atlantic are some of the lowest in the global ocean and have been hypothesized to constrain primary production. Based upon data from several transect cruises in this region, it has been hypothesized that dissolved organic phosphorus (DOP) supports a significant fraction of primary production in the subtropical North Atlantic. In this study, a time-series of phosphorus biogeochemistry is presented for the Bermuda Atlantic Time-series Study site, including rates of phosphorus export. Most parameters have a seasonal pattern, although year-over-year variability in the seasonal pattern is substantial, likely due to differences in external forcing. Suspended particulate phosphorus exhibits a seasonal maximum during the spring bloom, despite the absence of a seasonal peak in SRP. However, DOP concentrations are at an annual maximum prior to the winter/spring bloom and decline over the course of the spring bloom while whole community alkaline phosphatase activities are highest. As a result of DOP bioavailability, the growth of particles during the spring bloom occurs in Redfield proportions, though particles exported from the euphotic zone show rapid and significant remineralization of phosphorus within the first 50 m below the euphotic zone. Based upon DOP data from transect cruises in this region, the southward cross gyral flux of DOP is estimated to support ~25% of annual primary production and ~100% of phosphorus export. These estimates are consistent with other research in the subtropical North Atlantic and reinforce the hypothesis that while the subtropics may be phosphorus stressed (a physiological response to low inorganic phosphorus), utilization of the DOP pool allows production and accumulation of microbial biomass at Redfield proportions.This research was supported by the NSF Biological Oceanography Program through awards OCE-0453023 (MWL), OCE-0451419 (STD), OCE-0452904 (JWA). We also acknowledge support for the Bermuda Atlantic Time-series Study provided by the NSF Chemical and Biological Oceanography Programs through the most recent awards OCE 0326885 and OCE 0752366. CS thanks The Charrock Foundation and Princeton Environmental Institute for her support