Dosimetric properties of europium-doped potassium bromide thermoluminescent crystals.

The dosimetric thermoluminescent properties of potassium bromide crystals doped with europium have been investigated. Nominal concentrations of europium ions varied between 0.01% and 1%. The crystals were annealed prior to irradiation following different thermal treatments. We report the glow curve and dose-response characteristics to 60Co gamma rays. After a particular annealing, the crystals showed a strong thermoluminescent peak near 100 degrees C and a linear response for doses between 0.03 cGy and 10 cGy. The sensitivity is approximately 10 times that of lithium fluoride (TLD-100).     

Significantly reduced expression of the proteoglycan decorin in Alzheimer''s disease fibroblasts

Aims—To investigate whether proteoglycan synthesis is altered in skin fibroblasts in patients with Alzheimer's disease compared with normal subjects.     

Alterations in intervertebral disc composition,matrix homeostasis and biomechanical behavior in the UCD‐T2DM rat model of type 2 diabetes

Type 2 diabetes (T2D) adversely affects many tissues, and the greater incidence of discogenic low back pain among diabetic patients suggests that the intervertebral disc is affected too. Using a rat model of polygenic obese T2D, we demonstrate that diabetes compromises several aspects of disc composition, matrix homeostasis, and biomechanical behavior. Coccygeal motion segments were harvested from 6‐month‐old lean Sprague‐Dawley rats, obese Sprague‐Dawley rats, and diabetic obese UCD‐T2DM rats (diabetic for 69 ± 7 days). Findings indicated that diabetes but not obesity reduced disc glycosaminoglycan and water contents, and these degenerative changes correlated with increased vertebral endplate thickness and decreased endplate porosity, and with higher levels of the advanced glycation end‐product (AGE) pentosidine. Consistent with their diminished glycosaminoglycan and water contents and their higher AGE levels, discs from diabetic rats were stiffer and exhibited less creep when compressed. At the matrix level, elevated expression of hypoxia‐inducible genes and catabolic markers in the discs from diabetic rats coincided with increased oxidative stress and greater interactions between AGEs and one of their receptors (RAGE). Taken together, these findings indicate that endplate sclerosis, increased oxidative stress, and AGE/RAGE‐mediated interactions could be important factors for explaining the greater incidence of disc pathology in T2D. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:738–746, 2015.     

Extended access oxycodone self-administration and neurotransmitter receptor gene expression in the dorsal striatum of adult C57BL/6 J mice

Rationale

Although non-medical use of oxycodone continues to be a growing problem in the United States, there are no animal studies examining the effects of long-term oxycodone self-administration (SA).

Objectives

The current study was designed to examine chronic oxycodone SA by mice (14 days), in novel extended (4 h) SA sessions and its effect on selective striatal neurotransmitter receptor mRNA expression.

Methods

Adult male C57/BL6J mice were either allowed to self-administer oxycodone (0.25 mg/kg/infusion, FR1) or served as yoked-saline controls in an extended access paradigm. Mice self-administered oxycodone for 4 h/day for 14 consecutive days. Comparison groups with 14-days exposure to 1-h SA sessions were also studied. Within 1 h of the last extended SA session, mice were sacrificed, dorsal striatum was isolated and selective neurotransmitter receptor mRNA levels were examined.

Results

The oxycodone groups poked the active hole significantly more times than the yoked controls. The number of nose pokes at the active hole rose over the 14 days in the oxycodone group with extended access. The expression of 13 neurotransmitter receptor mRNAs was significantly altered in the dorsal striatum, including the gamma-aminobutyric acid (GABA) A receptor beta 2 subunit (Gabrb2) showing experiment-wise significant decrease, as a result of extended oxycodone SA.

Conclusion

C57BL/6 J mice escalated the amount of oxycodone self-administered across 14 consecutive daily extended sessions, but not 1-h sessions. Decreases in Gabrb2 mRNA levels may underlie escalation of oxycodone intake in the extended access SA sessions.     

Isolation of proteoglycans synthesized by rat heart: evidence for the presence of several distinct forms.

1. The proteoglycans (Ps) synthesized by auricle and ventricle from adult rat heart were studied. 2. Auricle tissue incorporated over two times radioactive sulfate compared to ventricle tissue and the Ps were mainly found in the detergent insoluble fraction. 3. The Ps from both tissues were isolated by ion-exchange chromatography on DEAE-Sephacel, followed by gel filtration on Sepharose CL-6B and SDS-PAGE electrophoresis. 4. Enzymatic and chemical degradation of these Ps suggest that at least three and probably four different species of Ps can be observed in heart tissue. 4. A high molecular weight chondroitin sulfate-P, a high molecular weight heparan sulfate-P, a chondroitin/dermatan sulfate-P of 240-200 kDa and a dermatan sulfate of 115 kDa. 5. This latter P was specifically immunoprecipitated using rat decorin antiserum.     

Evaluation of equipment performance, patient dose, imaging quality, and diagnostic coincidence in five Mexico City mammography services

BACKGROUND: Regulations concerning the use of x-rays in medical diagnoses were published in Mexico in 1997. In this work, we evaluate technical aspects of mammography services in the Mexico City area and radiation dose and coincidence between the radiological interpretation by the institution radiologist and by a panel of experts. METHODS: Following methodology proposed by the American College of Radiology and the European Community among others, we have evaluated the performance of six mammography systems in Mexico City public and private services. The studied services carry out approximately one half of the mammography studies in the capital's metropolitan area. RESULTS: The systems comply with 53-82% of a total of 31 applied quality control tests and measurements, which include the mammography unit, x-ray generation, collimation, automatic exposure control, compression devices, grid and image receptor, film processing, darkroom, viewboxes, dose, film rejection, and image quality. The elements that most frequently fail are film processing, darkroom, and light boxes; average ACR phantom score is 11.2 (9.5, 12.0); mean average glandular dose measured with the phantom is 1.00 (0.71-1.15) mGy, and measured in patients is 1.75 (0.3, 4.9) mGy; coincidence between radiologic reports (BI-RADS) by the institution radiologist and a panel of experts is obtained in 35% of studied cases. CONCLUSIONS: Statistical analysis of results indicated that the level of equipment performance is correlated with image quality, image quality estimated by the panel of radiologists is correlated with phantom score, and coincidence in clinical mammography reports is not correlated with equipment performance and appears to depend on the radiologist's experience.     

Panoramic view of a superfamily of phosphatases through substrate profiling

Large-scale activity profiling of enzyme superfamilies provides information about cellular functions as well as the intrinsic binding capabilities of conserved folds. Herein, the functional space of the ubiquitous haloalkanoate dehalogenase superfamily (HADSF) was revealed by screening a customized substrate library against >200 enzymes from representative prokaryotic species, enabling inferred annotation of ∼35% of the HADSF. An extremely high level of substrate ambiguity was revealed, with the majority of HADSF enzymes using more than five substrates. Substrate profiling allowed assignment of function to previously unannotated enzymes with known structure, uncovered potential new pathways, and identified iso-functional orthologs from evolutionarily distant taxonomic groups. Intriguingly, the HADSF subfamily having the least structural elaboration of the Rossmann fold catalytic domain was the most specific, consistent with the concept that domain insertions drive the evolution of new functions and that the broad specificity observed in HADSF may be a relic of this process.Since the first genomes were sequenced, there has been an exponential increase in the number of protein sequences deposited into databases worldwide. At the time of this writing the UniProtKB/TrEMBL database contains over 32 million protein sequences. Although this increase in sequence data has dramatically enhanced our understanding of the genomic organization of organisms, as the number of protein sequences grows, the proportion of firm functional assignments diminishes. Traditionally, methods of functional annotation involve comparing sequence identity between experimentally characterized proteins and newly sequenced ones, typically via BLAST (1). In cases where significant sequence similarity cannot be ascertained, proteins are annotated as “hypothetical” or “putative.” Moreover, the decrease in sequence identity leads to an increased uncertainty in functional assignment, especially as the phylogenetic distance between organisms grows, limiting iso-functional ortholog discovery.As the number of newly sequenced genomes grows larger, more protein sequences are likely to be misannotated, oftentimes resulting in the propagation of incorrect functional annotation across newly identified sequences. To tackle the problem of unannotated or misannotated proteins, newer methods for computational assignment have been created with varying degrees of success (2). Although these methods outperform historical methods, continued improvement is necessary to ensure accurate annotation of function (2). A greater swath of functional space can be covered by screening substrates in a high-throughput manner on multiple enzymes from a family (3, 4). Family-wide substrate profiling offers a data-rich resource. The use of sparse screening of sequence space and a diversified library permits the determination of substrate specificity profiles to provide a family-wide view of the range of substrates and insight into the structure of the prototypical substrate. Where structures are available, correlation between substrate range and structural determinants of specificity can be achieved. In addition, the approach has utility in genomic annotation (inferred function), iso-functional ortholog assignment, and the assignment of in vitro substrate profiles to orphaned PDB entries (enzymes with structure but no function, or SNFs). Here we report the application of in vitro high-throughput functional screening of metabolites and related compounds at the superfamily level. We use as an example prokaryotic members of the haloalkanoic acid dehalogenase superfamily (HADSF), a diverse superfamily of enzymes (5) that catalyze a wide range of reactions involving the formation of a covalent intermediate with an active-site aspartate. Reactions catalyzed by this superfamily include dehalogenation (6) as well as Mg²⁺-dependent phosphoryltransfer, although the vast majority (∼99%) are phosphotransferases (7). Members of the HADSF share a Rossmannoid fold “core” domain that contains the phosphoryl transfer site (8, 9) and a “cap” domain that provides substrate specificity determinants (10). There are three major types of caps in the HADSF (C0, C1, and C2A/C2B; see SI Appendix, Fig. S1) based on size, position of insert within the Rossmann fold, and overall topology (7). At the time of writing, the HADSF is known to comprise over 120,000 members across the three domains of life with at most 3% associated with an EC identifier (11).In this study, the functional space of the HADSF was sampled by screening a customized substrate library of 167 compounds against over 200 enzymes from numerous prokaryotic species. The study revealed that a large number of family members show a broad substrate range, with the majority of the HADSF enzymes reacting with five or more substrates. Thus, widespread promiscuity is not incompatible with participation in cell metabolism and may be advantageous to the evolution of new enzyme activities. The activity profiling when applied to putative iso-functional orthologs allowed us to infer annotation for ∼35% of the HADSF. Intriguingly, the HADSF subfamily with the least structural elaboration of the core catalytic Rossmann fold was the most specific with respect to substrate range and number, implying that domain insertions drive the evolution of new functions and that the broad specificity observed in the HADSF may be a relic of this process.