University of Arizona

About: University of Arizona is a education organization based out in Tucson, Arizona, United States. It is known for research contribution in the topics: Population & Galaxy. The organization has 63805 authors who have published 155998 publications receiving 6854915 citations. The organization is also known as: UA & U of A.

Phytostabilization of mine tailings in arid and semiarid environments--an emerging remediation technology.

Abstract: Mine tailings disposal sites from either inactive or abandoned mine sites are prevalent in arid and semiarid regions throughout the world. Major areas include northern Mexico and the Western United States, the Pacific coast of South America (Chile and Peru), southwestern Spain, western India, South Africa, and Australia (Munshower 1994; Tordoff et al. 2000). The global impact of such mine tailings disposal sites is enormous, as unreclaimed mining sites generally remain unvegetated for tens to hundreds of years, and exposed tailings can spread over tens of hectares via eolian dispersion and water erosion [Gonzalez and Gonzalez-Chavez 2006; Morris et al. 2003; Munshower 1994; U.S. Environmental Protection Agency (U.S. EPA) 2004; Warhurst 2000]. Mine tailings, or mill tailings, are the materials remaining after extraction and beneficiation of ores. What prevents the natural revegetation of mine tailings? It is generally a combination of factors beginning with metal toxicity. Tailings are characterized by elevated concentrations of metals such as arsenic, cadmium, copper, manganese, lead, and zinc (1–50 g/kg) (Boulet and Larocque 1998; Bradshaw et al. 1978; Walder and Chavez 1995). Further, tailings contain no organic matter or macronutrients, and usually exhibit acidic pH, although some tailings may be alkaline (Johnson and Bradshaw 1977; Krzaklewski and Pietrzykowski 2002). For these reasons, tailings remain without normal soil structure and support a severely stressed heterotrophic microbial community (Mendez et al. 2007; Southam and Beveridge 1992). Hence, the microbial community is extremely low in species richness and carbon utilization diversity compared with uncontaminated soil (Moynahan et al. 2002). Furthermore, autotrophic iron- and sulfur-oxidizing bacteria dominate the microbial community in mine tailings and are associated with plant death in acidic tailings (Schippers et al. 2000). In arid and semiarid regions, plant establishment on mine tailings is further impeded by a number of physicochemical factors including extreme temperatures especially at the tailings surface, low precipitation, and high winds. These factors contribute to the development of extremely high salt concentrations ranging up to 22 dS/m due to high evaporation and low water infiltration (Munshower 1994).

Microbiota Transfer Therapy alters gut ecosystem and improves gastrointestinal and autism symptoms: an open-label study

Abstract: Autism spectrum disorders (ASD) are complex neurobiological disorders that impair social interactions and communication and lead to restricted, repetitive, and stereotyped patterns of behavior, interests, and activities. The causes of these disorders remain poorly understood, but gut microbiota, the 1013 bacteria in the human intestines, have been implicated because children with ASD often suffer gastrointestinal (GI) problems that correlate with ASD severity. Several previous studies have reported abnormal gut bacteria in children with ASD. The gut microbiome-ASD connection has been tested in a mouse model of ASD, where the microbiome was mechanistically linked to abnormal metabolites and behavior. Similarly, a study of children with ASD found that oral non-absorbable antibiotic treatment improved GI and ASD symptoms, albeit temporarily. Here, a small open-label clinical trial evaluated the impact of Microbiota Transfer Therapy (MTT) on gut microbiota composition and GI and ASD symptoms of 18 ASD-diagnosed children. MTT involved a 2-week antibiotic treatment, a bowel cleanse, and then an extended fecal microbiota transplant (FMT) using a high initial dose followed by daily and lower maintenance doses for 7–8 weeks. The Gastrointestinal Symptom Rating Scale revealed an approximately 80% reduction of GI symptoms at the end of treatment, including significant improvements in symptoms of constipation, diarrhea, indigestion, and abdominal pain. Improvements persisted 8 weeks after treatment. Similarly, clinical assessments showed that behavioral ASD symptoms improved significantly and remained improved 8 weeks after treatment ended. Bacterial and phagedeep sequencing analyses revealed successful partial engraftment of donor microbiota and beneficial changes in the gut environment. Specifically, overall bacterial diversity and the abundance of Bifidobacterium, Prevotella, and Desulfovibrio among other taxa increased following MTT, and these changes persisted after treatment stopped (followed for 8 weeks). This exploratory, extended-duration treatment protocol thus appears to be a promising approach to alter the gut microbiome and virome and improve GI and behavioral symptoms of ASD. Improvements in GI symptoms, ASD symptoms, and the microbiome all persisted for at least 8 weeks after treatment ended, suggesting a long-term impact. This trial was registered on the ClinicalTrials.gov, with the registration number NCT02504554

An 800-million-solar-mass black hole in a significantly neutral Universe at a redshift of 7.5

Abstract: Observations of a quasar at redshift 7.54, when the Universe was just five per cent of its current age, suggest that the Universe was significantly neutral at this epoch. Despite extensive searches, only one quasar has been known at redshifts greater than 7, at 7.09. Eduardo Banados and colleagues report observations of a quasar at a redshift of 7.54, when the Universe was just 690 million years old, with a black-hole mass 800 million times the mass of the Sun. The spectrum shows that the quasar's Lyman α emission is being substantially absorbed by an intergalactic medium containing significantly neutral hydrogen, indicating that reionization was not complete at that epoch. Quasars are the most luminous non-transient objects known and as a result they enable studies of the Universe at the earliest cosmic epochs. Despite extensive efforts, however, the quasar ULAS J1120 + 0641 at redshift z = 7.09 has remained the only one known at z > 7 for more than half a decade1. Here we report observations of the quasar ULAS J134208.10 + 092838.61 (hereafter J1342 + 0928) at redshift z = 7.54. This quasar has a bolometric luminosity of 4 × 1013 times the luminosity of the Sun and a black-hole mass of 8 × 108 solar masses. The existence of this supermassive black hole when the Universe was only 690 million years old—just five per cent of its current age—reinforces models of early black-hole growth that allow black holes with initial masses of more than about 104 solar masses2,3 or episodic hyper-Eddington accretion4,5. We see strong evidence of absorption of the spectrum of the quasar redwards of the Lyman α emission line (the Gunn–Peterson damping wing), as would be expected if a significant amount (more than 10 per cent) of the hydrogen in the intergalactic medium surrounding J1342 + 0928 is neutral. We derive such a significant fraction of neutral hydrogen, although the exact fraction depends on the modelling. However, even in our most conservative analysis we find a fraction of more than 0.33 (0.11) at 68 per cent (95 per cent) probability, indicating that we are probing well within the reionization epoch of the Universe.

Disruption of hyaluronan synthase-2 abrogates normal cardiac morphogenesis and hyaluronan-mediated transformation of epithelium to mesenchyme

Abstract: We identified hyaluronan synthase-2 (Has2) as a likely source of hyaluronan (HA) during embryonic development, and we used gene targeting to study its function in vivo. Has2(-/-) embryos lack HA, exhibit severe cardiac and vascular abnormalities, and die during midgestation (E9.5-10). Heart explants from Has2(-/-) embryos lack the characteristic transformation of cardiac endothelial cells into mesenchyme, an essential developmental event that depends on receptor-mediated intracellular signaling. This defect is reproduced by expression of a dominant-negative Ras in wild-type heart explants, and is reversed in Has2(-/-) explants by gene rescue, by administering exogenous HA, or by expressing activated Ras. Conversely, transformation in Has2(-/-) explants mediated by exogenous HA is inhibited by dominant-negative Ras. Collectively, our results demonstrate the importance of HA in mammalian embryogenesis and the pivotal role of Has2 during mammalian development. They also reveal a previously unrecognized pathway for cell migration and invasion that is HA-dependent and involves Ras activation.

Drug-related morbidity and mortality: updating the cost-of-illness model

Abstract: Objective: To update the 1995 estimate .of $76.6 billion for the annual cost of drug-related morbidity and mortality resulting from drug-related problems (DRPs) in the ambulatory setting in the United States to reflect current treatment patterns and costs. Design: For this study, we employed the decision-analytic model developed by Johnson and Bootman. We used the model's original design and probability data, but used updated cost estimates derived from the current medical and pharmaceutical literature. Sensitivity analyses were performed on cost data and on probability estimates. Setting: Ambulatory care environment in the United States in the year 2000. Patients and Other Participants: A hypothetical cohort of ambulatory patients. Main Outcome Measures: Average cost of health care resources needed to manage DRPs. Results: As estimated using the decision-tree model, the mean cost for a treatment failure was $977. For a new medical problem, the mean cost was $1,105, and the cost of a combined treatment failure and resulting new medical problem was $1,488. Overall, the cost of drug-related morbidity and mortality exceeded $177.4 billion in 2000. Hospital admissions accounted for nearly 70% ($121.5 billion) of total costs, followed by long-term-care admissions, which accounted for 18% ($32.8 billion). Conclusion: Since 1995, the costs associated with DRPs have more than doubled. Given the economic and medical burdens associated with DRPs, strategies for preventing drug-related morbidity and mortality are urgently needed.