106 research outputs found
Growth and Age at Reproductive Maturity of the Carolina Pigmy Rattlesnake, Sistrurus m. miliarius (Reptilia: Serpentes)
Growth and age at reproductive maturity are life history attributes that play an important role in the development of proper management strategies. The Carolina Pigmy Rattlesnake, Sistrurus m. miliarius, is one of two dwarf rattlesnake species. The subspecies ranges from eastern NC to nearly the southern tip of SC and into the northeastern portion of GA. In NC, where the species’ status is of Special Concern, fragmentation and land development have destroyed most of its historic range. Its small size also makes it highly susceptible to predation. In some parts of the range, commercial collection is another pressure the species faces. Carolina Pigmy Rattlesnakes are difficult to study due to their elusive behavior; thus, little is known about their life history. I modeled growth and age at reproductive maturity for a stable population of pigmy rattlesnakes from a wildlife refuge in north-central SC. During a six-year mark-recapture study, I recorded growth intervals (snout to vent length, or SVL) from free-ranging Carolina Pigmy Rattlesnakes. I fit these data to both von Bertalanffy and logistic growth interval models and used residual error mean square for comparison. The von Bertalanffy model estimated age at reproductive maturity at 2.7 years (males) and 2.1 years (females), and asymptotic size at 46.7cm (42.3–51.5, males) and 45cm (36.4-53.7, females); the logistic model estimated maturity at 3.4 years (males) and 3 years (females), and a total length of 45.2cm (42.1–48.2, males) and 43.9cm (37.7–50, females). These results demonstrate an accelerated life history of Carolina Pigmy Rattlesnakes, especially when compared to other pit vipers. An understanding of these aspects of their life history is essential to a sound management plan
Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer Planning (OSIRIS-REx)
Scientists at ARES are preparing to curate and analyze samples from the first U.S. mission to return samples from an asteroid. The Origins-Spectral Interpretation- Resource Identification-Security-Regolith Explorer, or OSIRIS-REx, was selected by NASA as the third mission in its New Frontiers Program. The robotic spacecraft will launch in 2016 and rendezvous with the near-Earth asteroid Bennu, in 2020. A robotic arm will collect at least 60 grams of material from the surface of the asteroid to be returned to Earth in 2023 for worldwide distribution by the NASA Astromaterials Curation Facility at ARES
Sample Curation in Support of the OSIRIS-REx Asteroid Sample Return Mission
The OSIRIS-REx asteroid sample return mission launched to asteroid Bennu Sept. 8, 2016. The spacecraft will arrive at Bennu in late 2019, orbit and map the asteroid, and perform a touch and go (TAG) sampling maneuver in July 2020. After sample is stowed and confirmed the spacecraft will return to Earth, and the sample return capsule (SRC) will land in Utah in September 2023. Samples will be recovered from Utah [2] and then transported and stored in a new sample cleanroom at NASA Johnson Space Center in Houston [3]. The materials curated for the mission are described here. a) Materials Archive and Witness Plate Collection: The SRC and TAGSAM were built between March 2014 and Summer of 2015, and instruments (OTES,OVIRS, OLA, OCAMS, REXIS) were integrated from Summer 2015 until May 2016. A total of 395 items were received for the materials archive at NASA-JSC, with archiving finishing ~30 days after launch (with the final archived items being related to launch operations)[4]. The materials fall into several general categories including metals (stainless steel, aluminum, titanium alloys, brass and BeCu alloy), epoxies, paints, polymers, lubricants, non-volatile-residue samples (NVR), sapphire, and various miscellaneous materials. All through the ATLO process (from March 2015 until late August 2016) contamination knowledge witness plates (Si wafer and Al foil) were deployed in the various cleanrooms in Denver and KSC to provide an additional record of particle counts and volatiles that is archived for current and future scientific studies. These plates were deployed in roughly monthly increments with each unit containing 4 Si wafers and 4 Al foils. We archived 128 individual witness plates (64 Si wafers and 64 Al foils); one of each witness plate (Si and Al) was analyzed immediately by the science team after archiving, while the remaining 3 of each are archived indefinitely. Information about each material archived is stored in an extensive database at NASA-JSC, and key summary information for each will be presented in an online catalog. b) Bulk Asteroid sample: The Touch and Go Sampling Mechanism (TAGSAM) head will contain up to 1.5 kg of asteroid material. Upon return to Earth, the TAGSAM head with the sample canister will be subjected to a nitrogen purge and then opened in a nitrogen cabinet in Houston. Once the TAGSAM head is removed from the canister, it will be dis-assembled slowly and carefully under nitrogen until the sample can be removed for processing in a dedicated nitrogen glovebox. Bennu surface samples are expected to be sub-cm sized, based on thermal infrared and radar polarization ratio measurements [1]. The upper limit on material collected by the TAGSAM head is ~2 cm. Therefore, we will be prepared to handle, subdivide, and characterize materials of a wide grain size (from ~10 m to 2 cm), and for both organic (UV fluorescence) and inorganic (SEM, FTIR, optical) properties. Representative portions of the bulk sample will be prepared for JAXA (0.5 %; see also [5]) and Canadian Space Agency (4%), with the remaining divided between the science team (75%). c) Contact Pad samples: The base of the TAGSAM head contains 24 contact pads that are designed to trap the upper surface layer of material and thus offer an opportunity to study asteroid samples that have resided at the very top surface of the regolith. Asteroid material is trapped on the pads in spring steel Velcro hooks, and material will have to be removed from these pads by curation specialists in the lab. d) Hardware: Some canister and SRC hardware items will contain information that will be important to understanding the collected samples, including the canister gas filter, temperature strips, flight witness plates, and the TAGSAM and canister parts that might have adhering dust grains. Some challenges remaining for both bulk sample and contact pad samples include: i) working with intermediate size range (200 to 500 micron) samples - a size range NASA has not previously worked in such detail; ii) techniques for removal of contact pad material from the spring steel hooks, iii) static electrical effects of dust sized particles during sample handling and curation is likely to be significant, and iv) the TAGSAM head and associated canister hardware will undoubtedly be coated with fine adhering dust grains from Bennu. In the case of collection of a large bulk sample mass, the adhering dust grains may be of lower priority. If a small sample mass is returned, the adhering dust may attain a higher priority, so recovery of adhering dust grains is an additional challenge to consider. In the year leading up to sample return we plan a variety of sample handling rehearsals that will enables the curation team to be prepared for many new aspects posed by this sample suite
Osiris-Rex and Hayabusa2 Sample Cleanroom Design and Construction Planning at NASA-JSC
Final Paper and not the abstract is attached. The OSIRIS-REx asteroid sample return mission launched to asteroid Bennu September 8, 2016. The spacecraft will arrive at Bennu in late 2019, orbit and map the asteroid, and perform a touch and go (TAG) sampling maneuver in July 2020. After confirma-tion of successful sample stowage, the spacecraft will return to Earth, and the sample return capsule (SRC) will land in Utah in September 2023. Samples will be recovered from Utah and then transported and stored in a new sample cleanroom at NASA Johnson Space Center in Houston. All curation-specific ex-amination and documentation activities related to Ben-nu samples will be conducted in the dedicated OSIRIS-REx sample cleanroom to be built at NASA-JSC
NASA Curation Preparation for Ryugu Sample Returned by JAXA's Hayabusa2 Mission
The NASA OSIRIS-REx and JAXA Hayabusa2 missions to near-Earth asteroids Bennu and Ryugu share similar mission goals of understanding the origins of primitive, organic-rich asteroids. Under an agreement between JAXA and NASA, there is an on-going and productive collaboration between science teams of Hayabusa2 and OSIRIS-REx missions. Under this agreement, a portion of each of the returned sample masses will be exchanged between the agencies and the scientific results of their study will be shared. NASAs portion of the returned Hayabusa2 sample, consisting of 10% of the returned mass, will be jointly separated by NASA and JAXA. The sample will be legally and physically transferred to NASAs dedicated Hayabusa2 curation facility at Johnson Space Center (JSC) no later than one year after the return of the Hayabusa2 sample to Earth (December 2020). The JSC Hayabusa2 curation cleanroom facility design has now been completed. In the same manner, JAXA will receive 0.5% of the total returned OSIRIS-REx sample (minimum required sample to return 60 g, maximum sample return capacity of 2 kg) from the rest of the specimen. No later than one year after the return of the OSIRIS-REx sample to Earth (September 2023), legal, physical, and permanent custody of this sample subset will be transferred to JAXA, and the sample subset will be brought to JAXAs Extraterrestrial Sample Curation Center (ESCuC) at Institute of Space and Astronautical Science, Sagamihara City Japan
Comparative Effectiveness of Drug-Eluting Versus Bare-Metal Stents in Elderly Patients Undergoing Revascularization of Chronic Total Coronary Occlusions Results From the National Cardiovascular Data Registry, 2005–2008
ObjectivesThis study sought to investigate the long-term effectiveness of drug-eluting stents (DES) versus bare-metal stents (BMS).BackgroundImproved recanalization techniques have increased interest in percutaneous coronary intervention (PCI) for chronic total coronary occlusion (CTO). The long-term effectiveness of DES and BMS is not known.MethodsWe used data from 10,261 stable patients age ≥65 years at 889 U.S. hospitals who underwent CTO PCI from January 1, 2005, to December 31, 2008, in the NCDR (National Cardiovascular Data Registry) CathPCI Registry with linked Medicare inpatient claims for follow-up. Patient and procedural characteristics, and 30-month death, myocardial infarction, revascularization, and hospitalization for bleeding were evaluated by stent type. Outcomes following stenting were adjusted and compared using propensity score matching.ResultsDES were used for CTO PCI in 8,218 (80%) and BMS in 2,043 (20%). DES patients were younger (74.0 vs. 75.5 years, p < 0.001), had longer lesions (18.8 vs. 16.5 mm, p < 0.001), received more stents (≥2 stents in 45.7% vs. 37.9%, p < 0.001), and underwent multivessel PCI (18.9% vs. 15.1%, p < 0.001). DES implantation was associated with a lower hazard of mortality (hazard ratio [HR]: = 0.72, 95% confidence interval [CI]: 0.60 to 0.86, p < 0.001), a similar hazard for myocardial infarction (HR: 0.85, 95% CI: 0.61 to 1.19, p = 0.35), and subsequent revascularization (HR: 0.94, 95% CI: 0.79 to 1.12, p = 0.48), including PCI (HR: 0.98, 95% CI: 0.83 to 1.19, p = 0.87) and coronary artery bypass grafting (HR: 0.71, 95% CI: 0.46 to 1.10, p = 0.12). Hospitalization for bleeding was also similar for DES versus BMS (HR: 0.92; 95% CI: 0.61 to 1.39, p = 0.70).ConclusionsCompared with BMS, DES use in stable patients undergoing CTO PCI was associated with lower mortality, as well as similar myocardial infarction and repeat revascularization rates without an increase in subsequent bleeding requiring hospitalization
Percutaneous Coronary Intervention and Drug-Eluting Stent Use Among Patients ≥85 Years of Age in the United States
ObjectivesThis study assessed the comparative effectiveness of drug-eluting stents (DES) versus bare-metal stents (BMS) among patients ≥85 years of age.BackgroundDespite an aging population, little is known about the comparative effectiveness of DES versus BMS among patients age ≥85 years undergoing percutaneous coronary intervention (PCI).MethodsWe examined 471,006 PCI patients age ≥65 years at 947 hospitals in the National Cardiovascular Data Registry between 2004 and 2008 and linked to Medicare claims data. Long-term outcomes (median follow-up 640.8 ± 423.5 days) were compared between users of DES and BMS.ResultsPatients age ≥85 years comprise an increasing proportion of PCIs performed among elderly subjects, yet rates of DES use declined the most in this age group. Compared with BMS, use of DES was associated with lower mortality: age ≥85 years, 29% versus 38% (adjusted hazard ratio [HR]: 0.80 [95% confidence interval (CI): 0.77 to 0.83]); age 75 to 84 years, 17% versus 25% (HR: 0.77 [95% CI: 0.75 to 0.79]); and age 65 to 74 years, 10% versus 16% (HR: 0.73 [95% CI: 0.71 to 0.75]). However, the adjusted mortality difference narrowed with increasing age (pinteraction <0.001). In contrast, the adjusted HR for myocardial infarction rehospitalization associated with DES use was significantly lower with increasing age: age ≥85 years, 9% versus 12% (HR: 0.77 [95% CI: 0.71 to 0.83]); age 75 to 84 years, 7% versus 9% (HR: 0.81 [95% CI: 0.77 to 0.84]); and age 65 to 74 years, 7% versus 8% (HR: 0.84 [95% CI: 0.80 to 0.88]) (pinteraction <0.001).ConclusionsIn this national study of older patients undergoing PCI, declines in DES use were most pronounced among those aged ≥85 years, yet lower adverse-event rates associated with DES versus BMS use were observed
Yorkshire Lung Screening Trial (YLST): protocol for a randomised controlled trial to evaluate invitation to community-based low-dose CT screening for lung cancer versus usual care in a targeted population at risk
© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY. Published by BMJ. INTRODUCTION: Lung cancer is the world's leading cause of cancer death. Low-dose computed tomography (LDCT) screening reduced lung cancer mortality by 20% in the US National Lung Screening Trial. Here, we present the Yorkshire Lung Screening Trial (YLST), which will address key questions of relevance for screening implementation. METHODS AND ANALYSIS: Using a single-consent Zelen's design, ever-smokers aged 55-80 years registered with a general practice in Leeds will be randomised (1:1) to invitation to a telephone-based risk-assessment for a Lung Health Check or to usual care. The anticipated number randomised by household is 62 980 individuals. Responders at high risk will be invited for LDCT scanning for lung cancer on a mobile van in the community. There will be two rounds of screening at an interval of 2 years. Primary objectives are (1) measure participation rates, (2) compare the performance of PLCOM2012 (threshold ≥1.51%), Liverpool Lung Project (V.2) (threshold ≥5%) and US Preventive Services Task Force eligibility criteria for screening population selection and (3) assess lung cancer outcomes in the intervention and usual care arms. Secondary evaluations include health economics, quality of life, smoking rates according to intervention arm, screening programme performance with ancillary biomarker and smoking cessation studies. ETHICS AND DISSEMINATION: The study has been approved by the Greater Manchester West research ethics committee (18-NW-0012) and the Health Research Authority following review by the Confidentiality Advisory Group. The results will be disseminated through publication in peer-reviewed scientific journals, presentation at conferences and on the YLST website. TRIAL REGISTRATION NUMBERS: ISRCTN42704678 and NCT03750110
Trypanosoma cruzi genome plasticity and evolution
Trypanosoma cruzi, a protozoan from the Kinetoplastidae family, is the etiologic agent of Chagas disease, a major public health problem affecting mostly the poorest areas of Latin America. Due to the complex nature of the parasite’s genome it has been impossible to produce a complete reference genome sequence, thus hampering the implementation of post- genomic approaches to unveil the mechanisms of generation of antigenic variation and the identification of new drug targets. My doctoral studies have focused on the application of combined genome sequencing and computational methods to produce a complete reference T. cruzi genome sequence and perform comparative analyses to better understand the mechanisms that allow T. cruzi to evade the mammalian host immune system and to briskly adapt to novel environments.
In paper I and II, different genome assembly strategies and second generation sequencing technologies were implemented to perform comparative analyses to identify elements of virulence between T. cruzi and two trypanosomatids that are non-pathogenic to humans: Trypanosoma cruzi marinkellei, a bat-restricted sub-species of the T. cruzi clade and the human avirulent species Trypanosoma rangeli. The studies reveal the expansion of T. cruzi- specific genomic traits specialised in the invasion of mammalian cells.
In paper III, using third-generation, PacBio sequencing data it was possible to assemble the complete reference genome sequence of a Trypanosoma cruzi isolate from the DTU-I clade. This breakthrough allowed us - for the first time - to explore in detail the genome architecture of the subtelomeric areas where many parasite virulence factors are encoded. One of the most interesting discoveries was the overrepresentation of interspersed retrotransposons and microsatellites in tandem gene arrays coding for surface molecules, hinting at a retrotransposon-driven mechanism of recombination for generating new sequence variants. Whole genome sequencing of 35 T. cruzi DTU-I isolates, collected from different locations in the American continent, made possible to identify and characterise the mechanisms of adaptability employed by the parasite.
Finally, paper IV analyses the mechanisms of genomic hybridisation in T. cruzi and the evolution over time of the hybrid offspring. The analysis revealed that during hybrid formation, the parasite integrates genetic material from each parental strains with the aid of retrotransposons and microsatellites, and the genome of these hybrid isolates moves quickly from a tetraploid to a diploid state. As a result, the hybrid strain has more genetic material, mostly in the subtelomeres, providing the parasite with a pool of new surface molecule genes with the potential to possibly increase its fitness in a new environment.
In conclusion, the work presented here has advanced the understanding of parasite biology and provided a genomic resource to be exploited for the identification of drug targets and vaccine candidates
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