2,118 research outputs found

    Characterization of Glycated Proteins by \u3csup\u3e13\u3c/sup\u3eC NMR Spectroscopy

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    13C NMR spectroscopy has been used to characterize Amadori (ketoamine) adducts formed by reaction of [2-13C]glucose with free amino groups of protein. The spectra of glycated proteins were acquired in phosphate buffer at pH 7.4 and were interpreted by reference to the spectra of model compounds, N alpha-formyl-N epsilon-fructose-lysine and glycated poly-L-lysine (GlcPLL). The anomeric carbon region of the spectrum (approximately 90-105 ppm) of glycated cytochrome c was superimposable on that of N alpha-formyl-N epsilon-fructose-lysine, and contained three peaks characteristic of the alpha- and beta-furanose and beta-pyranose anomers of Amadori adducts to peripheral lysine residues on protein (pK alpha approximately 10.5). The spectrum of GlcPLL yielded six anomeric carbon resonances; the second set of three was displaced about 2 ppm to lower shielding of the first and was assigned to the Amadori adduct at the alpha-amino terminus (pK alpha approximately 7.5). The spectrum of glycated RNase was similar to that of GlcPLL, but contained a third set of three signals attributable to modification of active site lysine 41 (pK alpha approximately 8.8). The assignments for RNase were confirmed by analysis of spectra taken at pH 4 and under denaturing conditions. The spectrum of glycated hemoglobin was comparable to that of GlcPLL, and distinct resonances could be assigned to Amadori adducts at amino-terminal valine and intrachain N epsilon-lysine residues. Chemical analyses were performed to measure the relative extent of alpha- and epsilon-amino group modification in the glycated macromolecules, and the results were compared with estimates based on integration of the NMR spectra

    How to Reduce Tire-Pavement Noise: Interim Better Practices for Constructing and Texturing Concrete Pavement Surfaces

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    This report describes better practices for constructing and texturing quieter concrete pavements; better practices that answer the question of how we can reduce tire-pavement noise; and better practices that don\u27t compromise the other things about the pavement that are of equal or greater importance, including safety, cost, and durability. In developing this document, the National Concrete Pavement Technology Center at Iowa State University draws from its decades of combined experience working for and alongside concrete paving contractors. This document also includes the collective experience of various contractors and equipment manufacturers with a reputation for quality. These guidelines further address the challenges that are faced in consistently producing a high-quality product in a low-bid environment. This document is intended to serve as interim guidelines and better practices for texturing. Work under the pooled fund study that sponsored the development of this document is ongoing. Additional data are being collected on both existing and new concrete paving projects that will validate the practices described herein. Given the importance of this issue, however, it is believed that many of these practices can be implemented immediately without adverse consequences. Refinements to these practices can then be implemented as necessary as changes to these better practices are made in the near future

    \u3csup\u3e13\u3c/sup\u3eC NMR Investigation of Nonenzymatic Glucosylation of Protein

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    Nonenzymatic glucosylation of protein is initiated by the reversible condensation of glucose in its open chain form with the amino groups on the protein. The initial product is an aldimine (Schiff base) which cyclizes to the glycosylamine derivative. The aldimine can undergo a slow Amadori rearrangement to yield the relatively stable ketoamine adduct which is structurally analogous to fructose. 13C NMR has been used to characterize these early products of nonenzymatic glucosylation, using RNase A as a model protein. C-1 of the beta-pyranose anomer of the glycosylamine was identified at 88.8 ppm in the spectrum of RNase glucosylated approximately 1:1 with D-[1-13C]glucose. C-1 of the Amadori product was also apparent in this spectrum, resonating as a pair of intense peaks at 52.7 and 53.1 ppm. The anomeric (C-2) resonances of the Amadori adduct were seen in the spectrum of RNase glucosylated approximately 1:1 with [U-13C]glucose. This spectrum was interpreted by comparison to the spectra of reference compounds: D-fructose, fructose-glycine, N alpha-formyl-N epsilon-fructose-lysine, and glucosylated poly-L-lysine. In the protein spectrum, the most intense of the C-2 resonances was that of the beta-fructopyranose anomer at 95.8 ppm. The alpha- and beta-fructofuranose anomers were also observed at 101.7 and 99.2 ppm, respectively. One unidentified signal in the anomeric region was observed in the spectra of poly-L-lysine and RNase, both glucosylated with [U-13C]glucose; no comparable resonances were observed in the spectra of the model compounds

    The evolution of interdependence in a four-way mealybug symbiosis

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    Mealybugs are insects that maintain intracellular bacterial symbionts to supplement their nutrientpoor plant sap diets. Some mealybugs have a single betaproteobacterial endosymbiont, a Candidatus Tremblaya species (hereafter Tremblaya) that alone provides the insect with its required nutrients. Other mealybugs have two nutritional endosymbionts that together provide these nutrients, where Tremblaya has gained a gammaproteobacterial partner that resides in the cytoplasm of Tremblaya. Previous work had established that Pseudococcus longispinus mealybugs maintain not one but two species of gammaproteobacterial endosymbionts along with Tremblaya. Preliminary genomic analyses suggested that these two gammaproteobacterial endosymbionts have large genomes with features consistent with a relatively recent origin as insect endosymbionts, but the patterns of genomic complementarity between members of the symbiosis and their relative cellular locations were unknown. Here, using long-read sequencing and various types of microscopy, we show that the two gammaproteobacterial symbionts of P. longispinus are mixed together within Tremblaya cells, and that their genomes are somewhat reduced in size compared to their closest non-endosymbiotic relatives. Both gammaproteobacterial genomes contain thousands of pseudogenes, consistent with a relatively recent shift from a free-living to endosymbiotic lifestyle. Biosynthetic pathways of key metabolites are partitioned in complex interdependent patterns among the two gammaproteobacterial genomes, the Tremblaya genome, and horizontally acquired bacterial genes that are encoded on the mealybug nuclear genome. Although these two gammaproteobacterial endosymbionts have been acquired recently in evolutionary time, they have already evolved co-dependencies with each other, Tremblaya, and their insect host

    Crustal Shortening, Exhumation, and Strain Localization in a Collisonal Orogen: the Bajo Pequeno Shear Zone, Sierra de Pie de Palo, Argentina

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    The Bajo Pequeño Shear Zone (BPSZ) is a lower-crustal shear zone that records shortening and exhumation associated with the establishment of a new plate boundary, and its placement in a regional structural context suggests that local- to regional-scale strain localization occurred with progressive deformation. A kilometer-scale field and analytical cross section through the ~80 m thick BPSZ and its adjacent rocks indicates an early Devonian (405–400 Ma) phase of deformation on the western margin of Gondwanan continental crust. The earliest stages of the BPSZ, recorded by metamorphic and microstructural data, involved thrusting of a hotter orthogneiss over a relatively cool pelitic unit, which resulted in footwall garnet growth and reset footwall white mica 40Ar/39Ar ages in proximity to the shear zone. Later stages of BPSZ activity, as recorded by additional microstructures and quartz c-axis opening angles, were characterized by strain localization to the center of the shear zone coincident with cooling and exhumation. These and other data suggest that significant regional tectonism persisted in the Famatinian orogenic system for 60–70 million years after one microplate collision (the Precordillera) but ceased 5–10 million years prior to another (Chilenia). A survey of other synchronous structures shows that strain was accommodated on progressively narrower structures with time, indicating a regional pattern of strain localization and broad thermal relaxation as the Precordillera collision evolved

    Forest chimpanzees (Pan troglodytes verus) remember the location of numerous fruit trees

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    It is assumed that spatial memory contributes crucially to animal cognition since animals’ habitats entail a large number of dispersed and unpredictable food sources. Spatial memory has been investigated under controlled conditions, with different species showing and different conditions leading to varying performance levels. However, the number of food sources investigated is very low compared to what exists under natural conditions, where food resources are so abundant that it is difficult to precisely identify what is available. By using a detailed botanical map containing over 12,499 trees known to be used by the Taï chimpanzees, we created virtual maps of all productive fruit trees to simulate potential strategies used by wild chimpanzees to reach resources without spatial memory. First, we simulated different assumptions concerning the chimpanzees’ preference for a particular tree species, and, second, we varied the detection field to control for the possible use of smell to detect fruiting trees. For all these assumptions, we compared simulated distance travelled, frequencies of trees visited, and revisit rates with what we actually observed in wild chimpanzees. Our results show that chimpanzees visit rare tree species more frequently, travel shorter distances to reach them, and revisit the same trees more often than if they had no spatial memory. In addition, we demonstrate that chimpanzees travel longer distances to reach resources where they will eat for longer periods of time, and revisit resources more frequently where they ate for a long period of time during their first visit. Therefore, this study shows that forest chimpanzees possess a precise spatial memory which allows them to remember the location of numerous resources and use this information to select the most attractive resources

    Vibrational properties of amorphous silicon from tight-binding O(N) calculation

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    We present an O(N) algorithm to study the vibrational properties of amorphous silicon within the framework of tight-binding approach. The dynamical matrix elements have been evaluated numerically in the harmonic approximation exploiting the short-range nature of the density matrix to calculate the vibrational density of states which is then compared with the same obtained from a standard O(N4N^4) algorithm. For the purpose of illustration, an 1000-atom model is studied to calculate the localization properties of the vibrational eigenstates using the participation numbers calculation.Comment: 5 pages including 5 ps figures; added a figure and a few references; accepted in Phys. Rev.

    Management and control of tuberculosis control in socially complex groups: a research programme including three RCTs

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    Background: Socially complex groups, including people experiencing homelessness, prisoners and drug users, have very high levels of tuberculosis, often complicated by late diagnosis and difficulty in adhering to treatment. / Objective: To assess a series of interventions to improve tuberculosis control in socially complex groups. / Design: A series of observational surveys, evaluations and trials of interventions. / Setting: The pan-London Find&Treat service, which supports tuberculosis screening and case management in socially complex groups across London. / Participants: Socially complex groups with tuberculosis or at risk of tuberculosis, including people experiencing homelessness, prisoners, drug users and those at high risk of poor adherence to tuberculosis treatment. Interventions and main outcome measures We screened 491 people in homeless hostels and 511 people in prison for latent tuberculosis infection, human immunodeficiency virus, hepatitis B and hepatitis C. We evaluated an NHS-led prison radiographic screening programme. We conducted a cluster randomised controlled trial (2348 eligible people experiencing homelessness in 46 hostels) of the effectiveness of peer educators (22 hostels) compared with NHS staff (24 hostels) at encouraging the uptake of mobile radiographic screening. We initiated a trial of the use of point-of-care polymerase chain reaction diagnostics to rapidly confirm tuberculosis alongside mobile radiographic screening. We undertook a randomised controlled trial to improve treatment adherence, comparing face-to-face, directly observed treatment with video-observed treatment using a smartphone application. The primary outcome was completion of ≥ 80% of scheduled treatment observations over the first 2 months following enrolment. We assessed the cost-effectiveness of latent tuberculosis screening alongside radiographic screening of people experiencing homelessness. The costs of video-observed treatment and directly observed treatment were compared. / Results: In the homeless hostels, 16.5% of people experiencing homelessness had latent tuberculosis infection, 1.4% had current hepatitis B infection, 10.4% had hepatitis C infection and 1.0% had human immunodeficiency virus infection. When a quality-adjusted life-year is valued at £30,000, the latent tuberculosis screening of people experiencing homelessness was cost-effective provided treatment uptake was ≥ 25% (for a £20,000 quality-adjusted life-year threshold, treatment uptake would need to be > 50%). In prison, 12.6% of prisoners had latent tuberculosis infection, 1.9% had current hepatitis B infection, 4.2% had hepatitis C infection and 0.0% had human immunodeficiency virus infection. In both settings, levels of latent tuberculosis infection and blood-borne viruses were higher among injecting drug users. A total of 1484 prisoners were screened using chest radiography over a total of 112 screening days (new prisoner screening coverage was 43%). Twenty-nine radiographs were reported as potentially indicating tuberculosis. One prisoner began, and completed, antituberculosis treatment in prison. In the cluster randomised controlled trial of peer educators to increase screening uptake, the median uptake was 45% in the control arm and 40% in the intervention arm (adjusted risk ratio 0.98, 95% confidence interval 0.80 to 1.20). A rapid diagnostic service was established on the mobile radiographic unit but the trial of rapid diagnostics was abandoned because of recruitment and follow-up difficulties. We randomly assigned 112 patients to video-observed treatment and 114 patients to directly observed treatment. Fifty-eight per cent of those recruited had a history of homelessness, addiction, imprisonment or severe mental health problems. Seventy-eight (70%) of 112 patients on video-observed treatment achieved the primary outcome, compared with 35 (31%) of 114 patients on directly observed treatment (adjusted odds ratio 5.48, 95% confidence interval 3.10 to 9.68; p < 0.0001). Video-observed treatment was superior to directly observed treatment in all demographic and social risk factor subgroups. The cost for 6 months of treatment observation was £1645 for daily video-observed treatment, £3420 for directly observed treatment three times per week and £5700 for directly observed treatment five times per week. / Limitations: Recruitment was lower than anticipated for most of the studies. The peer advocate study may have been contaminated by the fact that the service was already using peer educators to support its work. / Conclusions: There are very high levels of latent tuberculosis infection among prisoners, people experiencing homelessness and drug users. Screening for latent infection in people experiencing homelessness alongside mobile radiographic screening would be cost-effective, providing the uptake of treatment was 25–50%. Despite ring-fenced funding, the NHS was unable to establish static radiographic screening programmes. Although we found no evidence that peer educators were more effective than health-care workers in encouraging the uptake of mobile radiographic screening, there may be wider benefits of including peer educators as part of the Find&Treat team. Utilising polymerase chain reaction-based rapid diagnostic testing on a mobile radiographic unit is feasible. Smartphone-enabled video-observed treatment is more effective and cheaper than directly observed treatment for ensuring that treatment is observed. / Future work: Trials of video-observed treatment in high-incidence settings are needed. / Trial registration: Current Controlled Trials ISRCTN17270334 and ISRCTN26184967. / Funding: This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full in Programme Grants for Applied Research; Vol. 8, No. 9. See the NIHR Journals Library website for further project information

    Interakcije nekih plijesni i aflatoksinogenog soja Asspergillus flavus NRRL 3251

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    The objective of this study was to evaluate biotic interaction between some mould species and active producer of aflatoxin B1 Aspergillus flavus NRRL 3251, co-cultured in yeast-extract sucrose (YES) broth. Twenty-five mould strains of Alternaria spp., Cladosporium spp., Mucor spp., A. flavus and A. niger, used as biocompetitive agents, were isolated from outdoor and indoor airborne fungi, scrapings of mouldy household walls, and from stored and post-harvest maize. Aflatoxin B1 was extracted from mould biomasses with chloroform and detected using the multitoxin TLC method. The results confirm antagonistic interaction between all strains tested. With Alternaria spp. and Cladosporium spp., aflatoxin B1 production decreased 100 %, compared to detection in a single culture of A. flavus NRRL 3251 (Cmean=18.7 µg mL-1). In mixed cultures with Mucor spp., aflatoxin B1 levels dropped to (5.6-9.3) µg mL-1, and the inhibition was from 50 % to 70 %. Four of five aflatoxin non-producing strains of A. flavus interfered with aflatoxin production in mixed culture, and reduced AFB1 productivity by 100 %. One strain showed a lower efficacy in inhibiting AFB1 production (80 %) with a detectable amount of AFB1 3.7 µg mL-1 when compared to control. A decrease in toxin production was also observed in dual cultivation with A. niger strains. It resulted in 100 % reduction in three strains), 90 % reduction in one strain (Cmean=1.9 µg mL-1) and 80 % reduction in one strain (Cmean=3.7 µg mL-1) inhibition.Cilj rada bio je procijeniti biotske interakcije između sojeva različitih vrsta plijesni i kontrolnog soja Aspergillus flavus NRRL 3251, producenta aflatoksina B1 (AFB1). Inhibitorno djelovanje u miješanim kulturama na tvorbu AFB1 ispitano je na dvadeset pet sojeva Alternaria, Cladosporium, Mucor i Aspergillus vrsta izoliranih iz zraka, strugotina pljesnivih zidova te uskladištenog i prezimljenog kukuruza. Biosinteze su provedene u tekućoj hranjivoj podlozi s kvaščevim ekstraktom (YESbujon). Ekstrakcije AFB1 iz biomase izvršene su multitoksinskom metodom tankoslojne kromatografije. Rezultati biotskih interakcija pokazali su antagonistički odnos svih testiranih sojeva. Alternaria i Cladosporium vrste simultano inokulirane sporama A. flavus NRRL 3251 inhibirale su tvorbu AFB1 100 % u odnosu na dokazani toksin u kontrolnoj biosintezi (konc. 18,7 µg mL-1). U miješanim kulturama vrstama roda Mucor dokazane su padajuće koncentracije AFB1 (9,3 µg mL-1, 7,5 µg mL-1 i 5,6 µg mL-1), odnosno inhibicija tvorbe toksina 50 % do 70 %. Atoksinogeni sojevi A. flavus inhibirali su tvorbu AFB1 80 % (1 soj, konc. 3,7 µg mL-1) i 100 % (4 soja). Antagonističko djelovanje prema toksinogenom soju, smanjujući tvorbu AFB1 u rasponu 80 % do 100 % (konc. 1,9 µg mL-1 i 3,7 µg mL-1), dokazano je u uzgojnim biosintezama s A. niger
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