Structural and chemical properties of anion exchanged CsPb(Br(1-x)Clx)3heterostructured perovskite nanowires imaged by nanofocused x-rays

Over the last years metal halide perovskites have demonstrated remarkable potential for integration in light emitting devices. Heterostructures allow for tunable bandgap depending on the local anion composition, crucial for optoelectronic devices, but local structural effects of anion exchange in single crystals is not fully understood. Here, we investigate how the anion exchange of CsPbBr3nanowires fully and locally exposed to HCl vapor affects the local crystal structure, using nanofocused x-rays. We study the nanoscale composition and crystal structure as function of HCl exposure time and demonstrate the correlation of anion exchange with changes in the lattice parameter. The local composition was measured by x-ray fluorescence and x-ray diffraction, with general agreement of both methods but with much less variation using latter. The heterostructured nanowires exhibit unintentional gradients in composition, both axially and radially. Ferroelastic domains are observed for all HCl exposure times, and the magnitude of the lattice tilt at the domain walls scales with the Cl concentration.

A novel method for calculating beta band burst durations in Parkinson's disease using a physiological baseline

BACKGROUND

Pathologically prolonged bursts of neural activity in the 8-30 Hz frequency range in Parkinson's disease have been measured using high power event detector thresholds.

NEW METHOD

This study introduces a novel method for determining beta bursts using a power baseline based on spectral activity that overlapped a simulated 1/f spectrum. We used resting state local field potentials from people with Parkinson's disease and a simulated 1/f signal to measure beta burst durations, to demonstrate how tuning parameters (i.e., bandwidth and center frequency) affect burst durations, to compare burst duration distributions with high power threshold methods, and to study the effect of increasing neurostimulation intensities on burst duration.

RESULTS

The baseline method captured a broad distribution of resting state beta band burst durations. Mean beta band burst durations were significantly shorter on compared to off neurostimulation (p = 0.0046), and their distribution shifted towards that of the 1/f spectrum during increasing intensities of stimulation.

COMPARISON WITH EXISTING METHODS

High power event detection methods, measure duration of higher power bursts and omit portions of the neural signal. The baseline method captured the broadest distribution of burst durations and was more sensitive than high power detection methods in demonstrating the effect of neurostimulation on beta burst duration.

CONCLUSIONS

The baseline method captured a broad range of fluctuations in beta band neural activity and demonstrated that subthalamic neurostimulation shortened burst durations in a dose (intensity) dependent manner, suggesting that beta burst duration is a useful control variable for closed loop algorithms.

Low-temperature Debye–Scherrer powder diffraction on Beamline I11 at Diamond

A bespoke capillary sample holder is described that attaches to the cold head of a commercially manufactured (PheniX) closed-cycle helium cryostat originally intended for flat-plate geometry. The new holder allows high-resolution synchrotron powder diffraction data to be collected from samples in Debye–Scherrer geometry over the temperature range 11–295 K. To demonstrate that high-quality powder data can be obtained using this new sample holder, structural refinement (Rietveld) and thermal expansion results measured from reference samples (Si and Al) are presented.

Expression of bacterial levanase in yeast enables simultaneous saccharification and fermentation of grass juice to bioethanol

This study demonstrates use of recombinant yeast to simultaneously saccharify and ferment grass juice (GJ) to bioethanol. A modified Bacillus subtilis levanase gene (sacC) in which the native bacterial signal sequence was replaced with a yeast α-factor domain, was synthesised with yeast codon preferences and transformed into Saccharomyces cerevisiae (strain AH22) using the expression vector pMA91. AH22:psacC transformants secreted sacCp as an active, hyper-glycosylated (>180 kDa) protein allowing them to utilise inulin (β[2-1] linked fructose) and levan (β[2-6] linkages) as growth substrates. The control (AH22:pMA91) strain, transformed with empty plasmid DNA was not able to utilise inulin or levan. When cultured on untreated GJ levels of growth and bioethanol production were significantly higher in experiments with AH22:psacC than with AH22:pMA91. Bioethanol yields from AH22:psacC grown on GJ (32.7[±4] mg mL(-1)) compared closely to those recently achieved (Martel et al., 2010) using enzymatically pre-hydrolysed GJ (36.8[±4] mg mL(-1)).

Expression, purification and use of the soluble domain of Lactobacillus paracasei beta-fructosidase to optimise production of bioethanol from grass fructans

Microbial inulinases find application in food, pharmaceutical and biofuel industries. Here, a novel Lactobacillus paracasei beta-fructosidase was overexpressed as truncated cytosolic protein ((t)fosEp) in Escherichia coli. Purified (t)fosEp was thermostable (10-50 degrees C) with a pH optimum of 5; it showed highest affinity for bacterial levan (beta[2-6] linked fructose) followed by nystose, chicory inulin, 1-kestose (beta[2-1] linkages) and sucrose (K(m) values of 0.5, 15, 15.6, 49 and 398 mM, respectively). Hydrolysis of polyfructose moieties in agriculturally-sourced grass juice (GJ) with (t)fosEp resulted in the release of >13 mg/ml more bioavailable fructose than was measured in untreated GJ. Bioethanol yields from fermentation experiments with Brewer's yeast and GJ+(t)fosEp were >25% higher than those achieved using untreated GJ feedstock (36.5[+/-4.3] and 28.2[+/-2.7]mg ethanol/ml, respectively). This constitutes the first specific study of the potential to ferment ethanol from grass juice and the utility of a novel core domain of beta-fructosidase from L. paracasei.

Association of chest radiographic abnormalities with tuberculosis disease in asymptomatic HIV-infected adults

SETTING

Francistown and Gaborone, Botswana.

OBJECTIVE

Chest radiography is used to screen for tuberculosis (TB) in asymptomatic persons living with the human immunodeficiency virus (PLWH) seeking isoniazid preventive therapy (IPT). We describe radiographic features in PLWH in a TB-endemic setting and identify features associated with TB disease.

DESIGN

Asymptomatic PLWH seeking IPT under program conditions for a clinical trial between 2004 and 2006 received chest radiographs (CXRs) that were read using the standardized Chest Radiograph Reading and Recording System (CRRS). Clinical characteristics, including TB disease, were compared with the radiographic findings.

RESULTS

From 2732 screening CXRs, 183 had one or more abnormalities and were scored using CRRS, with 42% having infiltrates (36% upper lobes), 35% parenchymal fibrosis and 32% adenopathy. TB disease status was determined in 129 (70%) PLWH, of whom 22 (17%) had TB disease. TB disease was associated with upper lobe infiltrates (relative risk [RR] 3.0, 95%CI 1.5-6.2) and mediastinal adenopathy (RR 3.9, 95%CI 1.8-8.4). The sensitivity and specificity of either upper lobe infiltrates or mediastinal lymphadenopathy for TB disease were respectively 64% and 82%.

CONCLUSION

A combination of CXR features was useful for predicting TB disease in asymptomatic PLWH. CRRS should be used more frequently in similar studies.

Beamline I11 at Diamond: a new instrument for high resolution powder diffraction

The performance characteristics of a new synchrotron x-ray powder diffraction beamline (I11) at the Diamond Light Source are presented. Using an in-vacuum undulator for photon production and deploying simple x-ray optics centered around a double-crystal monochromator and a pair of harmonic rejection mirrors, a high brightness and low bandpass x-ray beam is delivered at the sample. To provide fast data collection, 45 Si(111) analyzing crystals and detectors are installed onto a large and high precision diffractometer. High resolution powder diffraction data from standard reference materials of Si, alpha-quartz, and LaB6 are used to characterize instrumental performance.

The ikaite-to-vaterite transformation: new evidence from diffraction and imaging

Vaterite is one of three polymorphs of calcium carbonate (CaCO3) found in nature, the others being calcite and aragonite. Here the formation of vaterite from decomposition of ikaite (CaCO3·6H2O) was investigated using synchrotron powder diffraction and scanning electron microscopy. The crystallite sizes of vaterite (∼40 nm) were found to be much smaller than those of the precursor ikaite (∼0.5–1.0 µm) as a result of vaterite nucleating as ikaite dehydrates. The rate of decomposition to vaterite increases with temperature, indicating kinetic control of this transformation. It is postulated that the structural arrangement of the hydration sphere around Ca2+in ikaite determines the orientation of Ca2+and CO32−ions such that vaterite nucleates upon dehydration. This implies that the dehydration of a precursor hydrated phase such as ikaite is required for vaterite nucleation.

Differential azole antifungal efficacies contrasted using a Saccharomyces cerevisiae strain humanized for sterol 14 alpha-demethylase at the homologous locus

Inhibition of sterol-14 alpha-demethylase, a cytochrome P450 (CYP51, Erg11p), is the mode of action of azole antifungal drugs, and with high frequencies of fungal infections new agents are required. New drugs that target fungal CYP51 should not inhibit human CYP51, although selective inhibitors of the human target are also of interest as anticholesterol agents. A strain of Saccharomyces cerevisiae that was humanized with respect to the amino acids encoded at the CYP51 (ERG11) yeast locus (BY4741:huCYP51) was produced. The strain was validated with respect to gene expression, protein localization, growth characteristics, and sterol content. The MIC was determined and compared to that for the wild-type parental strain (BY4741), using clotrimazole, econazole, fluconazole, itraconazole, ketoconazole, miconazole, and voriconazole. The humanized strain showed up to >1,000-fold-reduced susceptibility to the orally active azole drugs, while the topical agents showed no difference. Data from growth kinetic measurements substantiated this finding but also revealed reduced effectiveness against the humanized strain for the topical drugs. Cellular sterol profiles reflected the decreased susceptibility of BY4741:huCYP51 and showed a smaller depletion of ergosterol and accumulation of 14 alpha-methyl-ergosta-8, 24(28)-dien-3beta-6 alpha-diol than the parental strain under the same treatment conditions. This strain provides a useful tool for initial specificity testing for new drugs targeting CYP51 and clearly differentiates azole antifungals in a side-by-side comparison.

Mixing in adsorbed monolayers: perfluorinated alkanes

The mixing behavior of binary combinations of perfluoroalkanes in the bulk and in solid monolayers adsorbed at the graphite/liquid interface, determined by calorimetry and powder diffraction, is reported. The perfluoroalkanes are found to generally have a smaller excess enthalpy of mixing on the surface than in the bulk, and their relative size ratio is a good parameter to predict the mixing behavior. The excess enthalpy of mixing for perfluoroalkanes is found to be significantly smaller than that of the closely related hydrocarbons. The preferential adsorption of longer homologues over shorter ones is observed. Interestingly, the extent of preferential adsorption with relative size ratio is very similar to that of the hydrocarbons. These results can be understood in terms of the increased compressibility and lower polarizability of the perfluoroalkanes compared to hydrocarbons.

The Crystalline Structures of Carboxylic Acid Monolayers Adsorbed on Graphite

X-ray and neutron diffraction have been used to investigate the formation of solid crystalline monolayers of all of the linear carboxylic acids from C(6) to C(14) at submonolayer coverage and from C(8) to C(14) at multilayer coverages, and to characterize their structures. X-rays and neutrons highlight different aspects of the monolayer structures, and their combination is therefore important in structural determination. For all of the acids with an odd number of carbon atoms, the unit cell is rectangular of plane group pgg containing four molecules. The members of the homologous series with an even number of carbon atoms have an oblique unit cell with two molecules per unit cell and plane group p2. This odd-even variation in crystal structure provides an explanation for the odd-even variation observed in monolayer melting points and mixing behavior. In all cases, the molecules are arranged in strongly hydrogen-bonded dimers with their extended axes parallel to the surface and the plane of the carbon skeleton essentially parallel to the graphite surface. The monolayer crystal structures have unit cell dimensions similar to certain close-packed planes of the bulk crystals, but the molecular arrangements are different. There is a 1-3% compression on increasing the coverage over a monolayer.

Selection of reference films based on reliability assessment of a classification of high-resolution computed tomography for pneumoconioses

OBJECTIVE

Worldwide demand has increased for the development of a computed tomography (CT) classification system that supplements the ILO classification of radiographs for pneumoconioses. The authors aimed to show preliminary reliability test results for selected referent films for the CT classification system developed through an international effort by researchers from seven countries.

METHODS

Reading trials by eight physicians who have considerable experience in pneumoconioses using a total of 114 lung zones consisting of 6 lung zones of 19 CT films of dust-exposed workers were performed to assess reliability of the classification system by weighted kappa. The results were also utilized for selecting reference films.

RESULTS

A good agreement was observed for both first and second reading trials for rounded opacities (weighted kappa=0.76, 0.74, first and second trial results, respectively), irregular opacities (0.60, 0.48), emphysema (0.56, 0.70) and honeycombing (0.72, 0.79). Ground glass opacities, on the other hand, showed moderate agreement (0.43, 0.38). Intra-reader agreements among eight readers were shown in the same table as the mean and standard deviation of weighted kappa statistics. The inter-reader agreement for pleural thickening was not as good as for parenchymal lesions.

DISCUSSION

The CT classification development may pioneer noble and sensitive medical screening for dust-exposed workers in selected settings. This system may be applied to radiographic borderline cases of profusion 0/1 and 1/0 by the ILO classification, in a setting that assures the occupational safety and health of workers exposed to some newly developed chemical compounds.

Allogeneic stem-cell transplantation for lymphoproliferative disorders using BEAM-CAMPATH (+/- fludarabine) conditioning combined with post-transplant donor-lymphocyte infusion

BACKGROUND

We report our updated experience of allogeneic transplantation in lympho-proliferative disorders using a reduced-intensity conditioning regimen combining BEAM (plus fludarabine in three cases) with pre-transplant CAMPATH. Post-transplant donor lymphocytes have been infused for persisting disease or relapse, and both chimerism and minimal residual disease have been monitored utilizing molecular techniques.

METHODS

Thirty patients with median age 47.6 years underwent allogeneic transplantation for relapsed or high-risk lymphoproliferative disease using HLA-identical (sibling n = 25, unrelated n = 2) or one antigen mismatched sibling donors (n = 3). Twenty-one had NHL, three had HD and six had CLL/PLL. Stem-cell source was PBSC (n = 24), BM (n = 5) or both (n = 1) with a median CD34 dose of 4.5 x 10(6)/kg. GvHD prophylaxis was with CYA and MTX.

RESULTS

Engraftment was prompt in the majority of patients, with a median of 15 days to both ANC > 0.5 and platelets > 20. There have been three transplant-related deaths secondary to viral pneumonitis or bacterial pneumonia. Seven patients developed Grade I-II acute GvHD post-transplant. Of 28 evaluable patients, 18 achieved a CR at assessment 2-3 months post-transplant and a further patient converted from PR to CR following DLI, to give an overall CR rate of 68%. Three patients had early progressive disease and six have relapsed from CR or progressed from PR (two of whom have achieved CR following DLI therapy). Overall survival is 67% and event-free survival 48% at 3 years. With a median follow-up of 1.3 years 57% of patients are currently alive and lymphoma-free. A molecular remission has been achieved in nine of 12 informative patients.

DISCUSSION

These encouraging results show that this reduced-intensity conditioning regimen is effective, with a low-toxicity profile compared with conventional TBI-based conditioning, and certainly merits further evaluation in this setting.

Genetic analysis of plant disease resistance pathways

Plant disease resistance (R) genes are introduced into high yielding crop varieties to improve resistance to agronomically important pathogens. The R gene-encoded proteins are recognitionally specific, interacting directly or indirectly with corresponding pathogen avirulence (avr) determinants, and are therefore under strong diversifying selection pressure to evolve new recognition capabilities. Genetic analyses in different plant species have also revealed more broadly recruited resistance signalling genes that provide further targets for manipulation in crop improvement strategies. Understanding the processes that regulate both plant-pathogen recognition and the induction of appropriate defences should provide fresh perspectives in combating plant disease. Many recent studies have utilized the model plant, Arabidopsis thaliana. Here, mutational screens have identified genes that are required for R gene function and for restriction of pathogen growth in compatible plant-pathogen interactions. Genetic analyses of these plant mutants suggest that whilst signalling pathways are conditioned by particular R protein structural types they are also influenced by pathogen lifestyle. Two Arabidopsis defence signalling genes, EDS1 and PAD4, are required for the accumulation of salicylic acid, a phenolic molecule required for systemic immunity. The cloning, molecular and biochemical characterization of these components suggests processes that may be important in their disease resistance signalling roles.

The disease resistance signaling components EDS1 and PAD4 are essential regulators of the cell death pathway controlled by LSD1 in Arabidopsis

Specific recognition of pathogens is mediated by plant disease resistance (R) genes and translated into a successful defense response. The extent of associated hypersensitive cell death varies from none to an area encompassing cells surrounding an infection site, depending on the R gene activated. We constructed double mutants in Arabidopsis between positive regulators of R function and a negative regulator of cell death, LSD1, to address whether genes required for normal R function also regulate the runaway cell death observed in lsd1 mutants. We report here that EDS1 and PAD4, two signaling genes that mediate some but not all R responses, also are required for runaway cell death in the lsd1 mutant. Importantly, this novel function of EDS1 and PAD4 is operative when runaway cell death in lsd1 is initiated through an R gene that does not require EDS1 or PAD4 for disease resistance. NDR1, another component of R signaling, also contributes to the control of plant cell death. The roles of EDS1 and PAD4 in regulating lsd1 runaway cell death are related to the interpretation of reactive oxygen intermediate-derived signals at infection sites. We further demonstrate that the fate of superoxide at infection sites is different from that observed at the leading margins of runaway cell death lesions in lsd1 mutants.

The disease resistance signaling components EDS1 and PAD4 are essential regulators of the cell death pathway controlled by LSD1 in Arabidopsis

Specific recognition of pathogens is mediated by plant disease resistance (R) genes and translated into a successful defense response. The extent of associated hypersensitive cell death varies from none to an area encompassing cells surrounding an infection site, depending on the R gene activated. We constructed double mutants in Arabidopsis between positive regulators of R function and a negative regulator of cell death, LSD1, to address whether genes required for normal R function also regulate the runaway cell death observed in lsd1 mutants. We report here that EDS1 and PAD4, two signaling genes that mediate some but not all R responses, also are required for runaway cell death in the lsd1 mutant. Importantly, this novel function of EDS1 and PAD4 is operative when runaway cell death in lsd1 is initiated through an R gene that does not require EDS1 or PAD4 for disease resistance. NDR1, another component of R signaling, also contributes to the control of plant cell death. The roles of EDS1 and PAD4 in regulating lsd1 runaway cell death are related to the interpretation of reactive oxygen intermediate-derived signals at infection sites. We further demonstrate that the fate of superoxide at infection sites is different from that observed at the leading margins of runaway cell death lesions in lsd1 mutants.

The disease resistance signaling components EDS1 and PAD4 are essential regulators of the cell death pathway controlled by LSD1 in Arabidopsis

Specific recognition of pathogens is mediated by plant disease resistance (R) genes and translated into a successful defense response. The extent of associated hypersensitive cell death varies from none to an area encompassing cells surrounding an infection site, depending on the R gene activated. We constructed double mutants in Arabidopsis between positive regulators of R function and a negative regulator of cell death, LSD1, to address whether genes required for normal R function also regulate the runaway cell death observed in lsd1 mutants. We report here that EDS1 and PAD4, two signaling genes that mediate some but not all R responses, also are required for runaway cell death in the lsd1 mutant. Importantly, this novel function of EDS1 and PAD4 is operative when runaway cell death in lsd1 is initiated through an R gene that does not require EDS1 or PAD4 for disease resistance. NDR1, another component of R signaling, also contributes to the control of plant cell death. The roles of EDS1 and PAD4 in regulating lsd1 runaway cell death are related to the interpretation of reactive oxygen intermediate-derived signals at infection sites. We further demonstrate that the fate of superoxide at infection sites is different from that observed at the leading margins of runaway cell death lesions in lsd1 mutants.

Vessel loops made easy

Vessel loops are invaluable in vascular surgery. Unfortunately, they frequently slide toward the ends of the arteriotomy, making precise stitch placement difficult. By bringing the vessel loops out separate stab wounds, we improve visualization at the heel and toe of the anastomosis while preserving arterial elevation and hemostasis.

Otitis media in a llama

A 7-month-old female llama was examined because of chronic otitis media and externa of 7 months' duration. Radiographically, the tympanic bullae appeared thicker than normal, and the ventral borders were poorly defined; the left external acoustic meatus (ear canal) appeared to be narrower than the right. The llama was treated with penicillin, and the ear canals were lavaged daily. Contrast radiography was performed on day 15 to determine the shape and size of the ear canals and evaluate the integrity of the tympanic membranes. Contrast medium was visible radiographically in the left tympanic bulla, indicating that the left tympanic membrane was ruptured, but the right tympanic membrane appeared to be intact. The left ear canal was narrower than the right, and the bony ear canals had a well-defined sigmoid shape. The right ear improved with medial treatment alone, but the left ear did not. Therefore, lateral ear canal resection was performed. After surgery, however, exudate was still evident in the left ear canal, and the llama became more lethargic and more reluctant to eat. Lateral bulla osteotomy was attempted, but no purulent material was obtained, and curettage of the bulla resulted in hemorrhage. Because of this and because of the llama's poor physical condition, a decision was made to euthanatize the llama. The sigmoid shape of the bony ear canal and the multicompartmental nature of the tympanic bulla make surgical treatment of otitis media and externa in llamas difficult. Further study of surgical treatments for otitis media in llamas is needed.

Constitutive disease resistance requires EDS1 in the Arabidopsis mutants cpr1 and cpr6 and is partially EDS1-dependent in cpr5

The systemic acquired resistance (SAR) response in Arabidopsis is characterized by the accumulation of salicylic acid (SA), expression of the pathogenesis-related (PR) genes, and enhanced resistance to virulent bacterial and oomycete pathogens. The cpr (constitutive expressor of PR genes) mutants express all three SAR phenotypes. In addition, cpr5 and cpr6 induce expression of PDF1.2, a defense-related gene associated with activation of the jasmonate/ethylene-mediated resistance pathways. cpr5 also forms spontaneous lesions. In contrast, the eds1 (enhanced disease susceptibility) mutation abolishes race-specific resistance conferred by a major subclass of resistance (R) gene products in response to avirulent pathogens. eds1 plants also exhibit increased susceptibility to virulent pathogens. Epistasis experiments were designed to explore the relationship between the cpr- and EDS1-mediated resistance pathways. We found that a null eds1 mutation suppresses the disease resistance phenotypes of both cpr1 and cpr6. In contrast, eds1 only partially suppresses resistance in cpr5, leading us to conclude that cpr5 expresses both EDS1-dependent and EDS1-independent components of plant disease resistance. Although eds1 does not prevent lesion formation on cpr5 leaves, it alters their appearance and reduces their spread. This phenotypic difference is associated with increased pathogen colonization of cpr5 eds1 plants compared to cpr5. The data allow us to place EDS1 as a necessary downstream component of cpr1- and cpr6-mediated responses, but suggest a more complex relationship between EDS1 and cpr5 in plant defense.

Rapid recovery and identification of anthrax bacteria from the environment

Bacillus anthracis has been recognized as a highly likely biological warfare or terrorist agent. We have designed culture techniques to rapidly isolate and identify "live" anthrax from suspected environmental release. A special medium (3AT medium) allows for discrimination between closely related bacilli and non-pathogenic strains. Nitrate was found to be a primary factor influencing spore formation in Bacillus anthracis. Nitrate reduction in anthrax is not an adaptation to saprophytic environmental existence, but it is a signal to enhance environmental survival upon the death of the anthrax host, which can be mimicked in culture.

Lydia Becker's "School for Science": a challenge to domesticity

Lydia Becker (1827-1890) is known as a leader of the Women's Suffrage Movement but little is known about her work to include women and girls in science. Before her energy was channelled into politics, she aimed to have a scientific career. Mid-Victorian Britain was a period in which women's intellect and potential were widely debated, and in which the dominant ideology was that their primary role in life was that of wife and mother. Science was widely regarded as a "masculine" subject which women were deliberately discouraged from studying. The author concentrates on the two main areas in which important contributions were made, the British Association for the Advancement of Science, and the Manchester School Board.

Arabidopsis map kinase 4 negatively regulates systemic acquired resistance

Transposon inactivation of Arabidopsis MAP kinase 4 produced the mpk4 mutant exhibiting constitutive systemic acquired resistance (SAR) including elevated salicylic acid (SA) levels, increased resistance to virulent pathogens, and constitutive pathogenesis-related gene expression shown by Northern and microarray hybridizations. MPK4 kinase activity is required to repress SAR, as an inactive MPK4 form failed to complement mpk4. Analysis of mpk4 expressing the SA hydroxylase NahG and of mpk4/npr1 double mutants indicated that SAR expression in mpk4 is dependent upon elevated SA levels but is independent of NPR1. PDF1.2 and THI2.1 gene induction by jasmonate was blocked in mpk4 expressing NahG, suggesting that MPK4 is required for jasmonic acid-responsive gene expression.

The role of apoptosis, proliferation, and the Bcl-2-related proteins in the myelodysplastic syndromes and acute myeloid leukemia secondary to MDS

Bone marrow CD34(+) cell apoptosis (annexin V), proliferation (Ki-67), and Bcl-2-related protein expression was evaluated by flow cytometry in 102 patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia secondary to MDS (MDS-AML) and in 30 normal donors (NBM). Apoptosis was significantly increased in refractory anemia (RA)/RA with ringed sideroblasts (RARS) (56.9% [20.4%-93.6%]) and refractory anemia with excess blasts (RAEB) (51.2% [25.2%-76. 6%]) compared with NBM (16.7% [3.4%-35.3%], P <.0001). In RA/RARS, apoptosis always exceeded proliferation (Ki-67-positivity, 26.1% [9.5%-47.8%]; apoptosis:proliferation ratio 2.08 [1.15-3.63]); whereas in RAEB, this ratio equalized (1.14 [0.93-2.08]) due to increased proliferation (40.4% [22%-69.5%]). Progression to RAEB in transformation (RAEB-t)/MDS-AML was associated with a significant reduction in apoptosis (22.3% [2.1%-53.2%]; P <.0001) and proliferation (16.8% [1.9%-75.8%); P =.04; ratio 1.69 [0.16-12.21]). Pro-apoptotic (Bax/Bad) versus anti-apoptotic (Bcl-2/Bcl-X) Bcl-2-related protein ratios were increased in RA/RARS compared with NBM (2.57 [1.93-9.42] versus 1.89 [0.65-4.1]; P =.06), whereas disease progression was associated with significantly reduced ratios (1.16 [0.06-3.32]; P <.0001) due primarily to increased Bcl-2 expression. Apoptosis and Bax/Bad:Bcl-2/Bcl-X ratio were inversely correlated with both International Prognostic Scoring System score and cytogenetic risk group; highest levels observed in patients with low score and/or good risk cytogenetics. There was a trend toward an association between Bcl-2-related protein expression and apoptosis (P =.07). This study indicates that MDS progression arises through multiple hits that alter levels of CD34(+) cell apoptosis and proliferation. Early disease is associated with excessive apoptosis and elevated ratio of apoptosis to proliferation. Increased proliferative rates are observed in RAEB, whereas leukemic transformation arises through inhibition of apoptosis rather than excessive cell growth. Although disease progression is accompanied by a fall in pro-apoptotic versus anti-apoptotic Bcl-2-related protein ratios, heterogeneity in patterns of protein expression indicates that factors additional to Bcl-2 family members play a role in the deregulated apoptosis in MDS. (Blood. 2000;96:3932-3938)

Excessive apoptosis in low risk myelodysplastic syndromes (MDS)

The paradox of peripheral cytopenias despite a normo/hypercellular marrow in MDS has been ascribed to excessive intramedullary hematopoietic cell apoptosis. Programmed cell death (PCD) in early disease might be triggered by the BM microenvironment, mediated either through inhibitory cytokines such as tumor necrosis factor alpha (TNF-alpha) or fas/fas ligand signaling or through a relative deficiency in hematopoietic growth factors. Intrinsic cellular defects giving rise to abnormalities in cell-cell or cell-stromal interaction, cell signaling or cell cycling may also underlie hematopoietic progenitor apoptosis. Alternatively, an early 'hit' in the multistep pathogenesis of MDS may result in a higher proliferative rate of the neoplastic clone. Increased apoptosis may thus represent a homeostatic process to control cell numbers. This paper shall summarize current evidence implicating a role for increased PCD in low risk MDS, outline possible etiologic factors and suggest potential therapeutic mechanisms whereby excessive hematopoietic progenitor cell apoptosis might be circumvented.

Epidemiologic investigation of respiratory morbidity at a nylon flock plant

BACKGROUND

A cluster of biopsy-confirmed interstitial lung disease among workers at a nylon flock plant led to a request for National Institute for Occupational Safety and Health investigators to conduct a health hazard evaluation.

METHODS

Part of the overall evaluation, reported here, involved a cross-sectional medical survey of current employees. The survey consisted of a questionnaire, spirometry and diffusing capacity testing, and chest radiograph.

RESULTS

Workers assigned to production and maintenance jobs reported frequent eye and throat irritation, respiratory symptoms, and systemic symptoms (i.e., generalized aches and fevers). Most reported improvement when away from work. Frequent respiratory/systemic symptom prevalence was significantly associated with departmental category, with days and hours worked per week, and with working on a flocking range. Compared to asymptomatic workers, symptomatic workers had similar mean ratios of forced expiratory volume in one second to forced vital capacity, but lower mean percent of predicted values for both forced vital capacity and diffusing capacity. All acceptable chest radiographs were classified as category 0 for small opacities.

CONCLUSIONS

Findings of this study, along with those from studies reported elsewhere, implicate occupational exposure to flock-associated dust as a significant respiratory health hazard at this plant.

Ultrasonographic diagnosis: cranial vena cava thrombosis in a cow

A 5-year-old Hereford cow was donated to Oregon State University, College of Veterinary Medicine. Two weeks before presentation the cow was treated by a left-flank laparotomy to correct a uterine torsion that revealed an excessive amount of abdominal fluid and a full term dead fetus. Ultrasonographic evaluation of the right cranioventral thoracic cavity was performed owing to physical examination (muffled heart sounds, areas of silence) and thoracocentesis findings suggestive of pleuritis. Ultrasonography revealed hypoechoic pleural effusion and a mass of mixed echogenicity visible within the right atrial lumen extending into the cranial vena cava. A diagnosis of cranial vena cava thrombosis was demonstrated at necropsy. The clinical, ultrasonographic, and pathological features of this less common condition (cranial vena cava thrombosis) in cattle are discussed.

Interplay of signaling pathways in plant disease resistance

Plants are under constant threat of infection by pathogens armed with a diverse array of effector molecules to colonize their host. Plants have, in turn, evolved sophisticated detection and response systems that decipher pathogen signals and induce appropriate defenses. Genetic analysis of plant mutants impaired in mounting a resistance response to invading pathogens has uncovered a number of distinct, but interconnecting, signaling networks that are under both positive and negative control. These pathways operate, at least partly, through the action of small signaling molecules such as salicylate, jasmonate and ethylene. The interplay of signals probably allows the plant to fine-tune defense responses in both local and systemic tissue.

cDNA-AFLP display for the isolation of Peronospora parasitica genes expressed during infection in Arabidopsis thaliana

To identify genes from the obligatory biotrophic oomycete Peronospora parasitica that are expressed during infection in Arabidopsis thaliana we employed cDNA-amplified fragment length polymorphism (AFLP) display. cDNA-AFLP fragments from infected and non-infected leaves were separated in parallel by gel electrophoresis and displayed by autoradiography. Most differential gene fragments were derived from P. parasitica.

Pulsed microwave induced light, sound, and electrical discharge enhanced by a biopolymer

Intense flashes of light were observed in sodium bicarbonate and hydrogen peroxide solutions when they were exposed to pulsed microwave radiation, and the response was greatly enhanced by a microwave-absorbing, biosynthesized polymer, diazoluminomelanin. A FPS-7B radar transmitter, operating at 1.25 GHz provided pulses of 5.73 +/- 0.09 micros in duration at 10.00 +/- 0.03 pulses/s with 2.07 +/- 0.08 MW forward power (mean +/- standard deviation), induced the effect but only when the appropriate chemical interaction was present. This phenomenon involves acoustic wave generation, bubble formation, pulsed luminescence, ionized gas ejection, and electrical discharge. The use of pulsed microwave radiation to generate highly focused energy deposition opens up the possibility of a variety of biomedical applications, including targeting killing of microbes or eukaryotic cells. The full range of microwave intensities and frequencies that induce these effects has yet to be explored and, therefore, the health and safety implications of generating the phenomena in living tissues remain an open question.

Intelligent database generated occupational questionnaire system

Obtaining an adequate occupational history requires special expertise to "ask the right questions" that are relevant to a particular patient's specific health conditions and potential exposures. This article describes a way to systematically accomplish this by means of a computer system that can overcome limited availability of necessary clinical occupational health expertise. The Intelligent Questionnaire system is a computer-based system for generating case-specific questionnaires about the influence of work on respiratory disease. Intelligent Questionnaire includes three databases: Questions, Responses, and Calls (clues to identify questions). The Questionnaire also arranges questions in a logical manner and provides a customized data entry screen for each subject. This approach provides primary practitioners with expertise on a case-by-case basis. It also facilitates occupational health surveillance because it allows acquiring detailed case-specific information in a systematic fashion. A computer-based system can facilitate obtaining occupational histories with high specificity and consistency without depending on general availability of a human occupational health clinical expertise.

Unravelling R gene-mediated disease resistance pathways in Arabidopsis

Abstract Molecular genetic approaches were adopted in the model crucifer, Arabidopsis thaliana, to unravel components of RPP5- and RPP1-mediated disease resistance to the oomycete pathogen, Peronospora parasitica. The products of RPP5 and three genes comprising the RPP1 complex locus belong to a major subclass of nucleotide-binding/leucine-rich repeat (NB-LRR) resistance (R) protein that has amino-terminal homology to the cytoplasmic domains of Drosophila and mammalian Toll and interleukin-1 family receptors (the so called 'TIR' domain). Similarities in the domain architecture of these proteins and animal regulators of programmed cell death have also been observed. Mutational screens revealed a number of genes that are required for RPP5-conditioned resistance. Among these are EDS1 and PAD4. Both EDS1 and PAD4 precede the function of salicylic acid-mediated plant responses. The EDS1 and PAD4 genes were cloned and found to encode proteins with similarity to the catalytic site of eukaryotic lipases, suggesting that they may function by hydrolysing a lipid-based substrate.

Arabidopsis thaliana PAD4 encodes a lipase-like gene that is important for salicylic acid signaling

The Arabidopsis PAD4 gene previously was found to be required for expression of multiple defense responses including camalexin synthesis and PR-1 gene expression in response to infection by the bacterial pathogen Pseudomonas syringae pv. maculicola. This report describes the isolation of PAD4. The predicted PAD4 protein sequence displays similarity to triacyl glycerol lipases and other esterases. The PAD4 transcript was found to accumulate after P. syringae infection or treatment with salicylic acid (SA). PAD4 transcript levels were very low in infected pad4 mutants. Treatment with SA induced expression of PAD4 mRNA in pad4-1, pad4-3, and pad4-4 plants but not in pad4-2 plants. Induction of PAD4 expression by P. syringae was independent of the regulatory factor NPR1 but induction by SA was NPR1-dependent. Taken together with the previous observation that pad4 mutants have a defect in accumulation of SA upon pathogen infection, these results suggest that PAD4 participates in a positive regulatory loop that increases SA levels, thereby activating SA-dependent defense responses.

Pronounced intraspecific haplotype divergence at the RPP5 complex disease resistance locus of Arabidopsis

In Arabidopsis ecotype Landsberg erecta (Ler), RPP5 confers resistance to the pathogen Peronospora parasitica. RPP5 is part of a clustered multigene family encoding nucleotide binding-leucine-rich repeat (LRR) proteins. We compared 95 kb of DNA sequence carrying the Ler RPP5 haplotype with the corresponding 90 kb of Arabidopsis ecotype Columbia (Col-0). Relative to the remainder of the genome, the Ler and Col-0 RPP5 haplotypes exhibit remarkable intraspecific polymorphism. The RPP5 gene family probably evolved by extensive recombination between LRRs from an RPP5-like progenitor that carried only eight LRRs. Most members have variable LRR configurations and encode different numbers of LRRs. Although many members carry retroelement insertions or frameshift mutations, codon usage analysis suggests that regions of the genes have been subject to purifying or diversifying selection, indicating that these genes were, or are, functional. The RPP5 haplotypes thus carry dynamic gene clusters with the potential to adapt rapidly to novel pathogen variants by gene duplication and modification of recognition capacity. We propose that the extremely high level of polymorphism at this complex resistance locus is maintained by frequency-dependent selection.

Pronounced intraspecific haplotype divergence at the RPP5 complex disease resistance locus of Arabidopsis

In Arabidopsis ecotype Landsberg erecta (Ler), RPP5 confers resistance to the pathogen Peronospora parasitica. RPP5 is part of a clustered multigene family encoding nucleotide binding-leucine-rich repeat (LRR) proteins. We compared 95 kb of DNA sequence carrying the Ler RPP5 haplotype with the corresponding 90 kb of Arabidopsis ecotype Columbia (Col-0). Relative to the remainder of the genome, the Ler and Col-0 RPP5 haplotypes exhibit remarkable intraspecific polymorphism. The RPP5 gene family probably evolved by extensive recombination between LRRs from an RPP5-like progenitor that carried only eight LRRs. Most members have variable LRR configurations and encode different numbers of LRRs. Although many members carry retroelement insertions or frameshift mutations, codon usage analysis suggests that regions of the genes have been subject to purifying or diversifying selection, indicating that these genes were, or are, functional. The RPP5 haplotypes thus carry dynamic gene clusters with the potential to adapt rapidly to novel pathogen variants by gene duplication and modification of recognition capacity. We propose that the extremely high level of polymorphism at this complex resistance locus is maintained by frequency-dependent selection.

Education and career paths of LSU's summer science program students from 1985 to 1997

Since 1985, the Louisiana State University School of Medicine in New Orleans, through its Office of Community and Minority Health Education, has operated the Summer Science Program for Louisiana high school students from underrepresented minorities. The authors conducted a survey during the 1997-98 academic year of the 773 students who had participated in the summer program from 1985 to 1997. The goal was to learn what education and career paths these students had taken since leaving the program. A total of 665 students (89.4%) responded. Sixty-one were still in high school, 11 had not continued their education after completing high school, but 432 of the remaining 583 students had chosen education paths in medicine, another health profession, or science, and 31 were enrolled in or had graduated from medical school. These findings indicate that the majority of the summer program students had maintained the health and/or science career interests they had expressed during their time in the program. Future studies will use control groups to better ascertain how influential the summer program was in helping students choose and maintain science and health education and career paths.

EDS1, an essential component of R gene-mediated disease resistance in Arabidopsis has homology to eukaryotic lipases

A major class of plant disease resistance (R) genes encodes leucine-rich-repeat proteins that possess a nucleotide binding site and amino-terminal similarity to the cytoplasmic domains of the Drosophila Toll and human IL-1 receptors. In Arabidopsis thaliana, EDS1 is indispensable for the function of these R genes. The EDS1 gene was cloned by targeted transposon tagging and found to encode a protein that has similarity in its amino-terminal portion to the catalytic site of eukaryotic lipases. Thus, hydrolase activity, possibly on a lipid-based substrate, is anticipated to be central to EDS1 function. The predicted EDS1 carboxyl terminus has no significant sequence homologies, although analysis of eight defective eds1 alleles reveals it to be essential for EDS1 function. Two plant defense pathways have been defined previously that depend on salicylic acid, a phenolic compound, or jasmonic acid, a lipid-derived molecule. We examined the expression of EDS1 mRNA and marker mRNAs (PR1 and PDF1.2, respectively) for these two pathways in wild-type and eds1 mutant plants after different challenges. The results suggest that EDS1 functions upstream of salicylic acid-dependent PR1 mRNA accumulation and is not required for jasmonic acid-induced PDF1.2 mRNA expression.