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Background and Purpose: Spiral MR imaging has several advantages compared with Cartesian MR imaging that can be leveraged for added clinical value. A multicenter multireader study was designed to compare spiral with standard-of-care Cartesian postcontrast structural brain MR imaging on the basis of relative performance in 10 metrics of image quality, artifact prevalence, and diagnostic benefit., Materials and Methods: Seven clinical sites acquired 88 total subjects. For each subject, sites acquired 2 postcontrast MR imaging scans: a spiral 2D T1 spin-echo, and 1 of 4 routine Cartesian 2D T1 spin-echo/TSE scans (fully sampled spin-echo at 3T, 1.5T, partial Fourier, TSE). The spiral acquisition matched the Cartesian scan for scan time, geometry, and contrast. Nine neuroradiologists independently reviewed each subject, with the matching pair of spiral and Cartesian scans compared side-by-side, and scored on 10 image-quality metrics (5-point Likert scale) focused on intracranial assessment. The Wilcoxon signed rank test evaluated relative performance of spiral versus Cartesian, while the Kruskal-Wallis test assessed interprotocol differences., Results: Spiral was superior to Cartesian in 7 of 10 metrics (flow artifact mitigation, SNR, GM/WM contrast, image sharpness, lesion conspicuity, preference for diagnosing abnormal enhancement, and overall intracranial image quality), comparable in 1 of 10 metrics (motion artifacts), and inferior in 2 of 10 metrics (susceptibility artifacts, overall extracranial image quality) related to magnetic susceptibility ( P < .05). Interprotocol comparison confirmed relatively higher SNR and GM/WM contrast for partial Fourier and TSE protocol groups, respectively ( P < .05)., Conclusions: Spiral 2D T1 spin-echo for routine structural brain MR imaging is feasible in the clinic with conventional scanners and was preferred by neuroradiologists for overall postcontrast intracranial evaluation., (© 2020 by American Journal of Neuroradiology.)

We report the whole genome sequence of the serotype e Cbm + strain LAR01 of Streptococcus mutans, a dental pathogen frequently associated with extra-oral infections. The LAR01 genome is a single circular chromosome of 2.1 Mb with a GC content of 36.96%. The genome contains 15 phosphotransferase system gene clusters, seven cell wall-anchored (LPxTG) proteins, all genes required for the development of natural competence and genes coding for mutacins VI and K8. Interestingly, the cbm gene is genetically linked to a putative type VII secretion system that has been found in Mycobacteria and few other Gram-positive bacteria. When compared with the UA159 type strain, phenotypic characterization of LAR01 revealed increased biofilm formation in the presence of either glucose or sucrose but similar abilities to withstand acid and oxidative stresses. LAR01 was unable to inhibit the growth of Strpetococcus gordonii, which is consistent with the genomic data that indicate absence of mutacins that can kill mitis streptococci. On the other hand, LAR01 effectively inhibited growth of other S. mutans strains, suggesting that it may be specialized to outcompete strains from its own species. In vitro and in vivo studies using mutational and heterologous expression approaches revealed that Cbm is a virulence factor of S. mutans by mediating binding to extracellular matrix proteins and intracellular invasion. Collectively, the whole genome sequence analysis and phenotypic characterization of LAR01 provides new insights on the virulence properties of S. mutans and grants further opportunities to understand the genomic fluidity of this important human pathogen., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The growth of low-dimensional nanostructures of Au on Ge(110) and their temperature-induced motion were observed with Low Energy Electron Microscopy (LEEM). Ge(110) was dosed with 0.5-4 ML of Au and heated to 850°C. Above 500°C, liquid AuGe eutectic alloy islands grew on the surface. Islands were 0.3-3.0µm in width, 1-10µm in length, and elongated in the [11¯0] direction. Above 600°C, islands began moving with speeds of 0.1-1.0µm/s, absorbing smaller stationary islands upon collision and increasing in size to more than 100µm in width. A temperature gradient of ∼0.017°C/µm across the sample results in a gradient in the Ge concentration across the islands, inducing their movement in the direction of increasing temperature. Optical microscopy confirmed that the large islands moved from the cooler edges of the sample towards its hotter center. The mechanism for motion of the droplets is discussed, and the island velocities fit well to a model for diffusion-driven motion of the liquid droplet. When the temperature was subsequently lowered, islands became supersaturated with Ge, which crystallized on the island edges., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Shell Chemical Company Nonidet P-40 has been used for decades in many biochemical assays as a nonionic, nondenaturing detergent; however, Shell no longer manufactures this product. Four commercially available substitutes were investigated and their activities titrated in an intracellular tubulin polymerization assay. Although claimed by the supply companies to be identical to the Shell Nonidet P-40, all four substitutes were about 10-fold more potent and needed to be diluted accordingly. As microtubule targeting drugs are a major class of anticancer agent, and many researchers use the intracellular tubulin polymerization assay, this information is important to help troubleshoot assay development with the new substitutes. As the Shell Nonidet P-40 has been used in many biochemical buffers, these results will be of general interest to the biochemical, cell, and molecular research community.

The ability of Streptococcus mutans to interact with collagen through the expression of collagen-binding proteins (CBPs) bestows this oral pathogen with an alternative to the sucrose-dependent mechanism of colonization classically attributed to caries development. Based on the abundance and distribution of collagen throughout the human body, stringent adherence to this molecule grants S. mutans with the opportunity to establish infection at different host sites. Surface proteins, such as SpaP, WapA, Cnm and Cbm, have been shown to bind collagen in vitro, and it has been suggested that these molecules play a role in colonization of oral and extra-oral tissues. However, robust collagen binding is not achieved by all strains of S. mutans, particularly those that lack Cnm or Cbm. These observations merit careful dissection of the contribution from these different CBPs towards tissue colonization and virulence. In this review, we will discuss the current understanding of mechanisms used by S. mutans and related streptococci to colonize collagenous tissues, and the possible contribution of CBPs to infections in different sites of the host., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background and Purpose: A challenge with the T1-weighted postcontrast Cartesian spin-echo and turbo spin-echo brain MR imaging is the presence of flow artifacts. Our aim was to develop a rapid 2D spiral spin-echo sequence for T1-weighted MR imaging with minimal flow artifacts and to compare it with a conventional Cartesian 2D turbo spin-echo sequence., Materials and Methods: T1-weighted brain imaging was performed in 24 pediatric patients. After the administration of intravenous gadolinium contrast agent, a reference Cartesian TSE sequence with a scanning time of 2 minutes 30 seconds was performed, followed by the proposed spiral spin-echo sequence with a scanning time of 1 minutes 18 seconds, with similar spatial resolution and volumetric coverage. The results were reviewed independently and blindly by 3 neuroradiologists. Scores from a 3-point scale were assigned in 3 categories: flow artifact reduction, subjective preference, and lesion conspicuity, if any. The Wilcoxon signed rank test was performed to evaluate the reviewer scores. The t test was used to evaluate the SNR. The Fleiss κ coefficient was calculated to examine interreader agreement., Results: In 23 cases, spiral spin-echo was scored over Cartesian TSE in flow artifact reduction (P < .001). In 21 cases, spiral spin-echo was rated superior in subjective preference (P < .001). Ten patients were identified with lesions, and no statistically significant difference in lesion conspicuity was observed between the 2 sequences. There was no statistically significant difference in SNR between the 2 techniques. The Fleiss κ coefficient was 0.79 (95% confidence interval, 0.65-0.93)., Conclusions: The proposed spiral spin-echo pulse sequence provides postcontrast images with minimal flow artifacts at a faster scanning time than its Cartesian TSE counterpart., (© 2016 by American Journal of Neuroradiology.)

Collision-induced dissociation (CID) is widely used in mass spectrometry to identify biologically important molecules by gaining information about their internal structure. Interpretation of experimental CID spectra always involves some form of in silico spectra of potential candidate molecules. Knowledge of how charge is distributed among fragments is an important part of CID simulations that generate in silico spectra from the chemical structure of the precursor ions entering the collision chamber. In this chapter we describe a method to obtain this knowledge by machine learning.

Background and Purpose: Acute activation of κ opioid (KOP) receptors results in anticocaine-like effects, but adverse effects, such as dysphoria, aversion, sedation and depression, limit their clinical development. Salvinorin A, isolated from the plant Salvia divinorum, and its semi-synthetic analogues have been shown to have potent KOP receptor agonist activity and may induce a unique response with similar anticocaine addiction effects as the classic KOP receptor agonists, but with a different side effect profile., Experimental Approach: We evaluated the duration of effects of Mesyl Sal B in vivo utilizing antinociception assays and screened for cocaine-prime induced cocaine-seeking behaviour in self-administering rats to predict anti-addiction effects. Cellular transporter uptake assays and in vitro voltammetry were used to assess modulation of dopamine transporter (DAT) function and to investigate transporter trafficking and kinase signalling pathways modulated by KOP receptor agonists., Key Results: Mesyl Sal B had a longer duration of action than SalA, had anti-addiction properties and increased DAT function in vitro in a KOP receptor-dependent and Pertussis toxin-sensitive manner. These effects on DAT function required ERK1/2 activation. We identified differences between Mesyl Sal B and SalA, with Mesyl Sal B increasing the Vmax of dopamine uptake without altering cell-surface expression of DAT., Conclusions and Implications: SalA analogues, such as Mesyl Sal B, have potential for development as anticocaine agents. Further tests are warranted to elucidate the mechanisms by which the novel salvinorin-based neoclerodane diterpene KOP receptor ligands produce both anti-addiction and adverse side effects., Linked Articles: This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2., (© 2014 The British Pharmacological Society.)

Unlabelled: Prior research suggests that cold temperatures may stimulate the proliferation of certain antibiotic resistance genes (ARGs) and gene transfer elements during storage of biosolids. This could have important implications on cold weather storage of biosolids, as often required in northern climates until a time suitable for land application. In this study, levels of an integron-associated gene (intI1) and an ARG (sul1) were monitored in biosolids subject to storage at 4, 10 and 20°C. Both intI1 and sul1 were observed to increase during short-term storage (<2 months), but the concentrations returned to background within 4 months. The increases in concentration were more pronounced at lower temperatures than ambient temperatures. Overall, the results suggest that cold stress may induce horizontal gene transfer of integron-associated ARGs and that biosolids storage conditions should be considered prior to land application., Significance and Impact of the Study: Wastewater treatment plants have been identified as the hot spots for the proliferation and dissemination of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) to the environment through discharge of treated effluent to water bodies as well as application of biosolids to land. Identifying critical control points within the treatment process may aid in the development of solutions for the reduction of ARGs and ARB and curbing the spread of antibiotic resistance. This study found increases in ARGs during biosolids storage and identifies changes in operational protocols that could help reduce ARG loading to the environment when biosolids are land-applied., (© 2014 The Society for Applied Microbiology.)

Cnm, a collagen- and laminin-binding protein present in a subset of Streptococcus mutans strains, mediates binding to extracellular matrices (ECM), intracellular invasion and virulence in the Galleria mellonella model. Antibodies raised against Cnm were used to confirm expression and the cell surface localization of Cnm in the highly invasive OMZ175 strain. Sequence analysis identified two additional genes (cnaB and cbpA) encoding putative surface proteins immediately upstream of cnm. Inactivation of cnaB and cbpA in OMZ175, individually or in combination, did not decrease the ability of this highly invasive and virulent strain to bind to different ECM proteins, invade human coronary artery endothelial cells (HCAEC), or kill G. mellonella. Similarly, expression of cnaB and cbpA in the cnm(-) strain UA159 revealed that these genes did not enhance Cnm-related phenotypes. However, integration of cnm in the chromosome of UA159 significantly increased its ability to bind to collagen and laminin, invade HCAEC, and kill G. mellonella. Moreover, the presence of antibodies against Cnm nearly abolished the ability of OMZ175 to bind to collagen and laminin and invade HCAEC, and significantly protected G. mellonella against OMZ175 infection. We concluded that neither CnaB nor CbpA is necessary for the expression of Cnm-related traits. We also provided definitive evidence that Cnm is an important virulence factor and a suitable target for the development of novel preventive and therapeutic strategies to combat invasive S. mutans strains., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: CT coronary angiography (CTCA) is an emerging diagnostic tool in the assessment of patients with suspected coronary artery disease. It has several advantages over conventional coronary angiography (CCA); however, its use is not yet widespread in large teaching centres., Aims: To determine what proportion of patients who have CTCA, do not require subsequent CCA., Methods: A prospective analysis of all patients referred for CTCA from the start of the service in January 2008 to April 2010., Results: CTCA provided definitive diagnostic images in 85% of patients. Overall only 12% (n = 33) of patients had subsequent CCA. The proportion of patients who subsequently had CCA reduced with time reflecting increasing confidence with the clinical service., Conclusions: A CTCA service can be successfully established out with a large teaching centre hospital. Close working between cardiologists and radiologists leads to increased confidence in the service and obviates the need for CCA in a large proportion of patients.

Recently observed Aharonov-Bohm quantum interference of the period h/2e in charge density wave rings strongly suggests that correlated density wave electron transport is a cooperative quantum phenomenon. The picture discussed here posits that quantum solitons nucleate and transport current above a Coulomb blockade threshold field. We propose a field-dependent tunneling matrix element and use the Schrödinger equation, viewed as an emergent classical equation as in Feynman's treatment of Josephson tunneling, to compute the evolving macrostate amplitudes, finding excellent quantitative agreement with voltage oscillations and current-voltage characteristics in NbSe(3). A proposed phase diagram shows the conditions favoring soliton nucleation versus classical depinning., (© 2012 American Physical Society)

Computed tomography (CT) coronary angiography is now a widely available and reliable test accessible on basic CT platforms that can exclude coronary heart disease with confidence. It is fast, cheap and, if properly carried out by trained and accredited staff in carefully selected patients, useful information can be obtained with acceptably low radiation exposure in some cases.

The human HOXA1 mutation syndromes commonly present with abnormalities of the inner ear and ICAs. Previous cases describe varying degrees of hypoplasia or aplasia of the affected structures, often with asymmetric involvement. We present imaging findings documenting complete absence of the ICAs bilaterally with bilateral CLA, which, to our knowledge, has not been previously reported.

Background and Purpose: Rapid brain MR imaging is often substituted for head CT in multiply imaged patients with shunted hydrocephalus. Fast TSE-T2 sequences are commonly used in these protocols. One limitation of TSE-T2 sequences is the decreased catheter delineation compared with CT. The aim of this study was to compare fast TSE-T2 with rapid SS-GRE sequences in the evaluation of intracranial shunt catheter delineation as part of a rapid nonsedated pediatric brain MR imaging protocol., Materials and Methods: We evaluated the findings from 179 consecutive patients who underwent routine clinical imaging according to the rapid nonsedated pediatric brain MR imaging protocol. Comparison of the quality of intracranial shunt catheter localization on SS-GRE versus TSE-T2 was performed., Results: Of the total of 179 rapid nonsedated pediatric brain MR images that were reviewed, 62 (35%) had an intracranial shunt catheter. The shunt catheter tip was better localized on the SS-GRE than on the TSE-T2 images in 49/62 (79%) of these patients. Of the remaining 13/62 (21%), the TSE-T2 was either better or equivalent in localizing the shunt catheter tip., Conclusions: Our study shows that rapid SS-GRE sequences can provide better delineation of standard intracranial shunt catheters than standard rapid MR imaging protocols containing only fast TSE-T2 sequences.

Similarly to humans, healthy, wild-type mice develop osteoarthritis, including of the temporomandibular joint (TMJ), as a result of aging. Pro-inflammatory cytokines, such as IL-1beta, IL-6, and TNFalpha, are known to contribute to the development of osteoarthritis, whereas TGFbeta has been associated with articular regeneration. We hypothesized that a balance between IL-1beta and TGFbeta underlies the development of TMJ osteoarthritis, whereby IL-1beta signaling down-regulates TGFbeta expression as part of disease pathology. Our studies in wild-type mice, as well as the Col1-IL1beta(XAT) mouse model of osteoarthritis, demonstrated an inverse correlation between IL-1beta and TGFbeta expression in the TMJ. IL-1beta etiologically correlated with joint pathology, whereas TGFbeta expression associated with IL-1beta down-regulation and improvement of articular pathology. Better understanding of the underlying inflammatory processes during disease will potentially enable us to harness inflammation for orofacial tissue regeneration.

Previous work by Morgan and coworkers on radiation-induced genome instability in Chinese hamster ovary (CHO) cell lines showed that unstable LS-12 cells had persistently elevated levels of reactive oxygen species (ROS) that were likely due to dysfunctional mitochondria. To further investigate the correlation between radiation-induced genome instability and dysfunctional mitochondria, we performed quantitative high-throughput mass spectrometry on samples enriched in mitochondrial proteins from three chromosomally unstable CHO cell lines and their stable unirradiated GM10115 parental cell line. Out of several hundred identified proteins, sufficient data were collected on 74 mitochondrial proteins to test for statistically significant differences in their abundance between unstable and stable cell lines. The LS-12 cell line, which exhibited the highest level of ROS among the three unstable cell lines, was characterized by eight significantly down-regulated mitochondrial proteins, all associated with the TCA (tricarboxylic acid). Elevated levels of ROS relative to the unirradiated parental control were also statistically significant for the CS-9 cell line. The protein profile of CS-9 revealed five significantly up-regulated mitochondrial proteins, three of which are involved in oxidative phosphorylation. Elevation of ROS in the unstable 115 cell line was nearly as large as that seen in CS-9 cells but was not statistically significant. The mitochondrial protein profile of 115 cells showed significant down-regulation of acetyl-CoA-acetyltransferase, which was also down-regulated in LS-12, and two other proteins with abundances that were significantly different from control levels but were not directly related to either the TCA or oxidative phosphorylation. These results provide further evidence that elevated ROS and mitochondrial dysfunction are associated with radiation-induced genome instability; however, additional work is required to establish a firm mechanistic relationship between these end points.

The etiology of midface retrusion remains largely unclear. We hypothesized that the cranial base synchondroses play a key role in the development of the craniofacial skeleton in the Sandhoff mouse model. We observed that developmental abnormalities of the cranial base synchondroses involving proliferative chondrocytes are important in craniofacial growth and development. Neonatal restitution of beta-hexosaminidase in mutant mice by gene therapy successfully ameliorated the attendant skeletal defects and restored craniofacial morphology in vivo, suggesting this as a critical temporal window in craniofacial development. Analysis of our data implicates parathyroid-related peptide (PTHrP) and cyclo-oxygenase-2 (COX-2) as possible factors underlying the development of the aforementioned skeletal defects. Hence, timely restitution of a genetic deficiency or, alternatively, the restoration of PTHrP or cyclo-oxygenase activity by the administration of PTH and/or non-steroidal anti-inflammatory drugs or COX-2 selective inhibitors to affected individuals may prove beneficial in the management of midface retrusion.

This article describes some recent improvements to simplify the test for heavy metals, avoiding loss of analytes and increasing sensitivity.

Tobacco smoking is a leading cause of preventable death around the world, and there are major public health and research efforts in many countries aimed at reducing its usage. However, the molecular mechanisms underlying tobacco dependence are still not completely understood. Nicotine's action on nicotinic acetylcholine receptors, and the downstream release of dopamine, is believed to be the major pathway underlying tobacco dependence. However there is mounting evidence indicating that non-nicotinic components of tobacco smoke also play a role by inhibiting monoamine oxidase (MAO) and subsequently altering neurotransmitter levels. This article provides a review of the current knowledge of the association between MAO and tobacco dependence and suggests that further research into this topic is likely to lead to more effective pharmacotherapies for smoking cessation.

The nocturnality hypothesis of K. Autumn and coworkers states that nocturnal geckos have evolved a low energetic cost of locomotion (C(min)). A low C(min) increases maximum aerobic speed and partially offsets the decrease in maximum oxygen consumption caused by activity at low nocturnal temperatures. We tested whether a low C(min) is unique to nocturnal geckos or represents a more general pattern of convergent evolution among lizards that enables nocturnality and/or cold-temperature activity. We measured C(min) in four carefully selected lizard species from New Zealand (two nocturnal and two diurnal; n=5-9 individuals per species), including a nocturnal and diurnal gecko (a low C(min) is a gecko trait and is not related to nocturnality), a nocturnal skink (a low C(min) is related to being nocturnal), and a diurnal skink active at low temperatures (a low C(min) is related to being active at low body temperatures). The C(min) values of the four species measured in this study (range=0.21-2.00 mL O(2) g(-1) km(-1)) are lower than those of diurnal lizards from elsewhere, and the values are within or below the 95% confidence limits previously published for nocturnal geckos. A low C(min) increases the range of locomotor speeds possible at low temperatures and provides an advantage for lizards active at these temperatures. We accepted the hypothesis that nocturnal lizards in general have a low C(min) and provide evidence for a low C(min) in lizards from cool-temperate environments. The low C(min) in lizards living at high latitudes may enable extension of their latitudinal range into otherwise thermally suboptimal habitats.

This report includes a brief review of the toxicology of hydrazine and the strategies used to set acceptance criteria. A preliminary examination of a number of approaches to determine hydrazine in pharmaceutical substances susceptible to its presence either as residue from the synthesis or from decomposition are described.

A reversed-phase liquid chromatographic method has been developed for the detection and control of impurities of imipramine hydrochloride at a level of 0.2 microg/ml (corresponding to 0.02 per cent in the procedure described). This method is included in a proposed revision of the monograph (Pharmeuropa 18.4) and replaces the thin-layer chromatographic method currently employed.

We report on harmonic generation by budding yeast cells (Saccharomyces cerevisiae, 10(8) cells/ml) in response to sinusoidal electric fields with amplitudes ranging from zero to 5 V/cm in the frequency range 10-300 Hz. The cell-generated harmonics are found to exhibit strong amplitude and frequency dependence. Sodium metavanadate, an inhibitor of the proton pump known as H+-ATPase, and glucose, a substrate of H+-ATPase, are found to increase harmonic production at low amplitudes while reducing it at large amplitudes. This P-type proton pump can be driven by an oscillatory transmembrane potential, and its nonlinear response is believed to be largely responsible for harmonic production at low frequencies in yeast cells. We find that the observed harmonics show dramatic changes with time and in their field and frequency dependence after perturbing the system by adding an inhibitor, substrate, or membrane depolarizer to the cell suspension.

The dependence of metabolic processes on temperature constrains the behavior, physiology and ecology of many ectothermic animals. The evolution of nocturnality in lizards, especially in temperate regions, requires adaptations for activity at low temperatures when optimal body temperatures are unlikely to be obtained. We examined whether nocturnal lizards have cold-adapted lactate dehydrogenase (LDH). LDH was chosen as a representative metabolic enzyme. We measured LDH activity of tail muscle in six lizard species (n=123: three nocturnal, two diurnal and one crepuscular) between 5 and 35 degrees C and found no differences in LDH-specific activity or thermal sensitivity among the species. Similarly, the specific activity and thermal sensitivity of LDH were similar between skinks and geckos. Similar enzyme activities among nocturnal and diurnal lizards indicate that there is no selection of temperature specific LDH enzyme activity at any temperature. As many nocturnal lizards actively thermoregulate during the day, LDH may be adapted for a broad range of temperatures rather than adapted specifically for the low temperatures encountered when the animals are active. The total activity of LDH in tropical and temperate lizards is not cold-adapted. More data are required on biochemical adaptations and whole animal thermal preferences before trends can be established.

Shedding, the release of cell surface proteins by regulated proteolysis, is a general cellular response to injury and is responsible for generating numerous bioactive molecules including growth factors and cytokines. The purpose of our work is to determine whether low doses of low-linear energy transfer (LET) radiation induce shedding of bioactive molecules. Using a mass spectrometry-based global proteomics method, we tested this hypothesis by analyzing for shed proteins in medium from irradiated human mammary epithelial cells (HMEC). Several hundred proteins were identified, including transforming growth factor beta (TGFB); however, no changes in protein abundances attributable to radiation exposure, based on immunoblotting methods, were observed. These results demonstrate that our proteomic-based approach has the sensitivity to identify the kinds of proteins believed to be released after low-dose radiation exposure but that improvements in mass spectrometry-based protein quantification will be required to detect the small changes in abundance associated with this type of insult.

We report on harmonic generation by budding yeast cells in response to a sinusoidal electric field, which is seen to be minimal when the field amplitude is less than a threshold value. Surprisingly, sodium metavanadate, an inhibitor of P-type ATPases reportedly responsible for nonlinear response in yeast, reduces the threshold field amplitude, increasing harmonic generation at low amplitudes while reducing it at large amplitudes, whereas the addition of glucose dramatically increases the production of even harmonics. Finally, a simple model is proposed to interpret the observed behavior.

Quantum calculations on duplex DNA trimers were used to model the changes in structure, hydrogen bonding, stacking properties, and electrostatic potential induced by oxidized purine bases and abasic (AP) sites. Results for oxidized purine bases were consistent with experimental data that show small structural and energetic perturbations induced by isolated 8-oxoguanine (8oG). Watson-Crick base pairing was preserved, and no major distortions of the backbone were induced. The thermal destabilization of DNA induced by 8oG was comparable to the energy of a single hydrogen bond. In contrast, AP sites caused substantial distortions of the DNA backbone that were accompanied by relocation of counterions. The loss of Watson-Crick hydrogen bonds in AP sites had the potential to destabilize DNA by 10-20 kcal/mol (0.4-0.8 eV); however, new inter- and intrastrand hydrogen bonds formed after removal of a nucleic acid base that significantly affected the energy of AP sites and introduced a strong dependence on sequence context. Quantum calculations on small DNA fragments provided starting conformations and force-field parameters for classical molecular dynamics simulations of radiation-induced single-strand breaks that most often combine hydrolysis of a phosphate-oxygen (P-O) bond with an AP site and fully or partially degraded sugar ring. P-O bond hydrolysis increased the freedom in backbone torsion angles, which allowed the broken strand to compress and partially fill the hole in the DNA created by the AP site. Results for strand breaks with a 3'phosphoglycolate were similar to those with phosphate end groups.

An isocratic reversed-phase liquid chromatographic method is described using a hybrid column for the control of synthetic impurities potentially found in amitriptyline hydrochloride. The method has been validated and is capable of controlling impurities to 0.1 per cent.

A reversed-phased liquid chromatographic method for the control of impurities of nine impurities in Chlortalidone drug substance is presented. The method is sufficiently sensitive to quantify down to the level of 0.0015 per cent equivalent to a concentration of 15 microg/ml.

We examined the changes in cardioventilatory synchronisation and breathing frequency variability that occur during early postnatal development in anaesthetised rats. Five-minute periods of heart rate and inspiratory timing data were recorded from 26 halothane anaesthetised, spontaneously breathing rats aged 2-14 days. The presence of cardioventilatory synchronisation was determined by examining the timing relationship between inspiratory onset and the preceding ECG R waves. We observed synchronisation at all ages, and the degree of synchronisation present (measured as the Shannon entropy of the interval between inspiration and the immediately preceding R wave) did not correlate with age. Frequent apnoeas were observed in the respiratory frequency time series. The duration of these apnoeas was close to either one or two times the duration of the immediately preceding breath. We suggest that these "dropped breaths" may be the consequence of a resetting of the respiratory oscillator just prior to initiation of the breath, or a gating process beneath the oscillator that intermittently blocks the mechanical initiation of breaths. Dropped breaths were seen commonly in rats up to 11 days of age, but rarely in 11-14-day old rats, and were not associated with the presence or absence of cardioventilatory synchronisation.

Dosimetry calculations characterizing the spatial variation of the energy deposited by the slowing and stopping of energetic electrons are reported and compared with experimental measurements from an electron microbeam facility. The computations involve event-by-event, detailed-histories Monte Carlo simulations of low-energy electrons interacting in water vapor. Simulations of electron tracks with starting energies from 30 to 80 keV are used to determine energy deposition distributions in thin cylindrical rings as a function of penetration and radial distance from a beam source. Experimental measurements of the spatial distribution of an electron microbeam in air show general agreement with the density-scaled simulation results for water vapor at these energies, yielding increased confidence in the predictions of Monte Carlo track-structure simulations for applications of the microbeam as a single-cell irradiator.

A model for sustained shedding of epidermal growth factor (EGF) in response to low doses of gamma radiation was developed based on a time delay in the feedback from mitogen-activated protein kinase (MAPK) activation to metalloprotease activity in an autocrine signaling process. We determined the kinetic parameters of our model using the data available for MAPK activation by gamma irradiation in the 1-2-Gy dose range and then showed that predictions of the model were consistent with experimental results for the kinetics of EGF shedding into the growth medium after exposure of human mammary epithelial cells to 1-5 cGy of gamma radiation in the presence of antibodies that block ligand binding to EGF receptors. The model allowed us to estimate the rate of radiation-induced cytokine release per cell from measurements of EGF concentration in the growth medium and to assess the effectiveness of EGF shedding and subsequent diffusion through the medium as a mechanism for signal transmission between hit cells and bystanders.

Reactions between metals and chloride solutions have been shown to exhibit magnetic field fluctuations over a wide range of size and time scales. Power law behavior observed in these reactions is consistent with models said to exhibit self-organized criticality. Voltage fluctuations observed during the dissolution of magnesium and aluminum in copper chloride solution are qualitatively similar to the recorded magnetic signals. In this paper, distributions of voltage and magnetic peak sizes, noise spectra, and return times are compared for both reactions studied., ((c) 2004 American Institute of Physics.)

In the European Pharmacopoeia, the monographs on somatropin, somatropin bulk solution and somatropin for injection prescribe a number of tests including "related substances", "dimer and related substances of higher molecular weight" and "isoform distribution" which are intended to control the levels of impurities in the substance. The aim of this study was to verify the robustness of a new method by capillary electrophoresis and to compare its performance with that of the existing test for "isoform distribution" by isoelectric focusing. It was demonstrated that the capillary electrophoresis method was superior to the method of isoelectric focusing. The interest of the CZE method consists in the resolution of related impurities that might be process specific and/or generated by the expression system.

Peloruside A (peloruside), a compound isolated from the marine sponge Mycale hentscheli , inhibits growth of human (HL-60) and mouse (32D-ras) myeloid leukemic cells, as well as non-transformed 32D cells. Using the MTT cell proliferation assay and trypan blue dye exclusion tests, little difference was seen in growth inhibition between 32D and 32D- ras cells; however, peloruside was more cytotoxic to the oncogene-transformed cells. Peloruside also blocked 32D- ras cells more readily in G2/M of the cell cycle, leading to apoptosis. Annexin-V/propidium iodide staining of 32D and 32D- ras cells showed that 1.6 microM peloruside induced significant cell death by 36 hours in 32D cells (16% survival), but to comparable levels as early as 14 hours in 32D- ras cells (11% survival). There was no evidence for activation of either of the initiator caspases-8 or -9 by 0.1 microM peloruside following 12 hours of exposure. Peloruside inhibited T cell proliferation and IL-2 and IFN gamma production in both the mixed lymphocyte reaction and following CD3 cross-linking, and this effect was shown to be a non-specific cytotoxic effect. It is concluded that peloruside preferentially targets oncogene-transformed cells over non-transformed cells by inducing transformed cells to undergo apoptosis.

Track structures of 25, 50 and 80 keV primary electrons, simulated by the detailed-history Monte Carlo method, were analyzed for the frequency distributions of energy deposited in spheres with a diameter of 1 microm, placed in a cylindrically symmetrical array around the projected initial direction of the primary electron. The frequency mean of specific energy, the dose mean of lineal energy, and the parameters of lognormal functions fit to the dose distributions were calculated as a function of beam penetration and radial distance from the projected beam axis. Given these data, the stochastics of dose and radiation quality for micrometer-scale sites targeted by a medium-energy electron microbeam can be predicted as a function of the site's location relative to the beam entry point.

The rate of oxygen consumption (VO2) is commonly used as a measure of whole organism metabolic rate, but requires the animal to be motionless and at rest. Few studies have measured whether animals that appear motionless are truly at rest, or whether being in a novel environment elevates metabolic rate. We investigated whether conditioning of the gecko Naultinus manukanus to experimental procedures influenced the VO2 and probability of achieving a constant rate of oxygen consumption. Metabolic rate was measured at 24 degrees C in 22 individuals until a steady-state was achieved, or for 80 min if no steady-state was reached, once a day on 5 consecutive days (five trials). Geckos in the first trial, when compared with subsequent trials, had a significantly higher mass-adjusted VO2 (0.89+/-0.06 vs. 0.67+/-0.05 ml O2 h(-1), respectively), and time to reach a steady-state VO2 (66+/-8 vs. 47+/-3 min, respectively), as well as a significantly lower probability of reaching a steady-state VO2 (24% vs. 74%, respectively). We conclude that there may be hidden inaccuracies in studies that do not condition animals and that at least one conditioning trial should be used to obtain a metabolic rate at rest for small lizards.

An implementation is presented of interaction cross sections for non-relativistic electron track structure simulations. The model, incorporating liquid-phase cross sections for inelastic interactions and improved algorithms for elastic scattering, is applied to Monte Carlo simulation of the track structure of low-energy electrons. Benchmark distributions and mean values are presented for several measures of penetration distances that characterize the general physical extent of the track structure. The results indicate that, except for the last approximately 500 eV of energy loss, electron tracks have a quasi-linear character; this suggests that a major part of an electron track may be reasonably described by a lineal-energy-like characterization.

Gene therapy is emerging as a novel treatment method for the management of temporomandibular joint disorders. The aim of this investigation was to study the effects of lentiviral vectors on the temporomandibular joint. Consequently, we injected into the articular joint space a defective feline immunodeficiency virus capable of infecting dividing as well as terminally differentiated cells with the reporter gene lacZ, the expression of which was studied by means of PCR, X-gal histochemistry, and beta-galactosidase immunocytochemistry. Our results showed successful transduction of hard and soft tissues of the temporomandibular joint. Interestingly, a subset of primary sensory neurons of the ipsilateral trigeminal ganglion also stained positive for the reporter gene, presumably following uptake of the lentiviral vector by peripheral nerve fibers and retrograde transport to the nucleus. These findings suggest that lentiviral vectors can potentially serve as a platform for the transfer of anti-nociceptive genes for the management of temporomandibular joint pain.

Collaborative studies were initiated by the European Directorate for the Quality of Medicines (EDQM) to assign potency values for candidate European Pharmacopoeia Chemical Reference Substances (Ph. Eur. CRSs) used for the microbiological assay of antibiotics. The candidates were assayed against their respective International Standard (IS), using the methods by diffusion or turbidimetry. Potencies were assigned to all the antibiotics concerned, which were adopted by the European Pharmacopoeia Commission.

The contents of Euglena gracilis cells can be separated in vivo by ultracentrifugation. Within the unbroken cell, each set of components forms a distinct layer according to their respective densities. The degree of segregation increases with both the g-force and the time of centrifugation, up to a maximum at 100,000 x g for 1 h, when six distinct strata can be observed. When returned to normal growth conditions, essentially all the cells return to the normal state and growth pattern. Greater g-forces or longer exposures do not alter the observable strata, but the ability of the cells to recover is diminished. Smaller g-forces result in less separation of cellular contents and all cells recover, even after 18 h of exposure. Euglena cells stratified at 100,000 x g for 1 h were returned to normal growth conditions; recovery was followed microscopically and by the rate of utilization of oxygen as well as that of the single carbon source. The cells recovered their normal state within 1 to 2 h, which is only a tenth of the normal doubling time. The mechanism for this recovery involves a natural process of change in cell shape caused by contraction and relaxation of the pellicle, a cell surface structure.

Two liquid chromatographic methods have been developed and validated for the determination of nitrilotriacetic acid (NTA) in edetic acid (EDTA) and its salts. In one method NTA and EDTA are separated on a polymer column without pretreatment, and are detected amperometrically using a glassy-carbon electrode. In the other method NTA and EDTA are complexed with ferric ions and the complexes separated on a porous graphite carbon stationary phase with ultraviolet detection at 215 nm. Both methods were sufficiently selected and sensitive to allow the control of NTA (0.1% m/m) in sample of EDTA and its salts.

Frozen rabbit immunoglobulin G was exposed to high-energy electrons. The surviving polypeptide subunits were determined and analyzed by radiation target analysis. Each subunit was independently damaged by radiation whether or not they were bound by disulfide bridges to other subunits, demonstrating that in IgG radiation-deposited energy did not travel across disulfide bonds.

Objective: To establish the magnitude and time course of the changes in water diffusion coefficient (D(av)) following newborn infant brain injury., Methods: Ten newborn infants at high risk for perinatal brain injury were recruited from the neonatal intensive care unit. Conventional and diffusion tensor MRI was performed on three occasions during the first week of life. Regions of injury were determined by evaluating conventional MR images (T1, T2, fluid-attenuated inversion recovery) at 1 week after injury. D(av) values were determined for these regions for all three scans., Results: D(av) values were decreased in most infants 1 day after injury, but injury was not evident or underestimated in 4 of 10 infants despite the presence of injury on conventional imaging at 1 week. By the third day, D(av) values were decreased in injured areas in all infants, reaching a nadir of approximately 35% less than normal values. By the seventh day after injury, D(av) values were returning to normal (pseudonormalization)., Conclusions: MR diffusion images (for which contrast is determined by changes in D(av)) obtained on the first day after injury do not necessarily show the full extent of ultimate injury in newborn infants. Images obtained between the second and fourth days of life reliably indicate the extent of injury. By the seventh day, diffusion MR is less sensitive to perinatal brain injury than conventional MR because of transient pseudonormalization of D(av). Overall, diffusion MR may not be suitable as a gold standard for detection of brain injury during the first day after injury in newborn infants.

The progress in the development of a sensor for the detection of trace air constituents to monitor spacecraft air quality is reported. A continuous-wave (cw), external-cavity tunable diode laser centered at 1.55 micrometers is used to pump an optical cavity absorption cell in cw-cavity ringdown spectroscopy (cw-CRDS). Preliminary results are presented that demonstrate the sensitivity, selectivity and reproducibility of this method. Detection limits of 2.0 ppm for CO, 2.5 ppm for CO2, 1.8 ppm for H2O, 19.4 ppb for NH3, 7.9 ppb for HCN and 4.0 ppb for C2H2 are calculated.

Background: The differentiation of bone infarction from acute osteomyelitis in patients with sickle-cell disease is challenging, as the clinical presentations of the two conditions are similar and imaging and laboratory studies are of limited value., Methods: A combination of radionuclide bone-marrow and bone scans was performed sequentially within a twenty-four-hour period (with one exception) to aid in the differentiation between bone infarction and osteomyelitis in seventy-nine consecutive episodes of acute bone pain in children with sickle-cell disease., Results: Seventy cases of bone infarction were diagnosed on the basis of decreased uptake on the bone-marrow scan and abnormal uptake on the bone scan at the site of pain. Antibiotic administration was discontinued in sixty-six of the seventy cases after the imaging results were obtained, and the bone pain resolved. In four of the seventy-nine cases, there was normal uptake on the bone-marrow scan and abnormal uptake on the bone scan at the site of pain, findings that were suggestive of acute osteomyelitis. In three of these cases, osteomyelitis was proven by culture, and the symptoms in all four resolved with antibiotic treatment. In five of the seventy-nine cases, the bone-marrow and bone scans were normal and thought to indicate neither osteomyelitis nor bone infarction; in all of these cases, the symptoms resolved without the use of antibiotics., Conclusions: These findings suggest that osteomyelitis can be differentiated from bone infarction in children with sickle-cell anemia and acute bone pain by a combination of sequential bone-marrow and bone scintigraphy.

The hydrolysis of GTP in p21(ras) triggers conformational changes that regulate the ras/ERK signaling pathway. An important active site residue is Gln61, which has been found to be mutated in 30% of human tumors. The dynamics of the active site conformation is studied by using molecular dynamics simulation of two independent structures of the GTP-bound uncomplexed enzyme. Two distinct conformations of the enzyme are observed, in which the side-chain residue Gln61 is in different orientations. Essential dynamics analysis is used to describe the essential motions in the transition between the two conformations. Results are compared with earlier simulations of p21(ras) and its complex with GTPase activating protein p21-GAP., (Copyright 2001 Wiley-Liss, Inc.)

We discuss a method for measuring electro-optic coefficients by measuring diffraction from a tunable grating. The method involves measuring the changes in the diffraction pattern of a reflection grating, where applied electric fields of alternating direction induce changes in the index of refraction through the electro-optic effect. For certain geometries, these applied fields cause period-doubling effects that produce new peaks in the diffraction pattern. Numerically calculated diffraction patterns are presented for the assumptions of both homogeneous and inhomogeneous fields. Peak splitting, as a function of both the number of slits illuminated and the induced change in the index of refraction, is observed and discussed. Finally, the usefulness of our method for the measurement of electro-optic coefficients is discussed.