Simulation of internal stress waves generated by laser-induced damage in multilayer dielectric gratings.

Multilayer dielectric (MLD) gratings used in ultrahigh-intensity laser systems often exhibit a laser-induced damage performance below that of their constituent materials. Reduced performance may arise from fabrication- and/or design-related issues. Finite element models were developed to simulate stress waves in MLD grating structures generated by laser-induced damage events. These models specifically investigate the influence of geometric and material parameters on how stress waves can lead to degradation of material structural integrity that can have adverse effects on its optical performance under subsequent laser irradiation: closer impedance matching of the layer materials reduces maximum interface stresses by ~20% to 30%; increasing sole thickness from 50 nm to 500 nm reduces maximum interface stresses by ~50%.

Assessing junk food consumption among Australian children: trends and associated characteristics from a cross-sectional study.

BACKGROUND: The ubiquitous supply of junk foods in our food environment has been partly blamed for the increased rates in overweight and obesity. However, consumption of these foods has generally been examined individually perhaps obscuring the true extent of their combined consumption and impact on health. An overall measure of children's junk food consumption may prove useful in the development of child obesity prevention strategies. We describe the development of a children's Junk Food Intake Measure (JFIM) to summarise temporal change in junk food consumption and examine the association between the JFIM and health-related behaviours. METHODS: Cross-sectional population surveillance survey of Australian children age 5-16 years collected in 2010 and 2015. Data were collected by questionnaire with parent's proxy reporting for children in years K, 2 and 4 and children in years 6, 8 and 10 by self-report. Information on diet, screen-time and physical activity was collected using validated questionnaires. The JFIM comprised consumption of fried potato products, potato crisps/salty snacks, sweet and savoury biscuits/cakes/doughnuts, confectionary and, ice cream/ice blocks. RESULTS: A total of 7565 (missing = 493, 6.1%) and 6944 (missing n = 611, 8.1%) children had complete data on consumption of junk foods, in 2010 and 2015, respectively. The 2015 survey data showed that among students from high socio-economic status neighbourhoods, there were fewer high junk food consumers than low junk food consumers. Children from Middle Eastern cultural backgrounds had higher junk food consumption. High junk food consumers were more likely to consume take-away ≥3/week, eat dinner in front of the television, receive sweet rewards, be allowed to consume snacks anytime, have soft drinks available at home and a TV in their bedroom. There was a lower proportion of high junk food consumers in 2015 compared to 2010. CONCLUSION: This is the first study to provide and examine a summary measure of overall junk food consumption among Australian children. The results indicate that junk food consumption among Australian children is lower in 2015, compared with 2010. Still, the public health workforce must continue their efforts as levels of junk food consumption remain of concern among Australian children.

Does nausea and vomiting of pregnancy play a role in the association found between maternal caffeine intake and fetal growth restriction?

The aim of this study was to explore the relationships between nausea and vomiting in pregnancy and (a) fetal growth restriction; and (b) maternal caffeine metabolism and fetal growth restriction. A cohort of 2,643 pregnant women, aged 18-45 years, attending two UK maternity units between 8 and 12 weeks gestation, was recruited. A validated tool assessed caffeine intake at different stages of pregnancy and caffeine metabolism was assessed from a caffeine challenge test. Experience of nausea and vomiting of pregnancy was self-reported for each trimester. Adjustment was made for confounders, including salivary cotinine as a biomarker of current smoking status. There were no significant associations between fetal growth restriction and nausea and vomiting in pregnancy, even after adjustment for smoking and alcohol intake. There were no significant differences in the relationship between caffeine intake and fetal growth restriction between those experiencing symptoms of nausea and vomiting and those who did not, for either the first (p = 0.50) or second trimester (p = 0.61) after adjustment for smoking, alcohol intake and caffeine half-life. There were also no significant differences in the relationship between caffeine half-life and fetal growth restriction between those experiencing symptoms of nausea and vomiting and those who did not, for either the first trimester (p = 0.91) or the second trimester (p = 0.45) after adjusting for smoking, alcohol intake and caffeine intake. The results from this study show no evidence that the relationship between maternal caffeine intake and fetal growth restriction is modified by nausea and vomiting in pregnancy.

The expression of native and cultured human retinal pigment epithelial cells grown in different culture conditions.

AIM: To determine the transcriptional proximity of retinal pigment epithelium (RPE) cells grown under different culture conditions and native RPE. METHODS: ARPE-19 cells were grown under five conditions in 10% CO(2): "subconfluent" in DMEM/F12+10% FBS, "confluent" in serum and serum withdrawn, and "differentiated" for 2.5 months in serum and serum withdrawn medium. Native RPE was laser microdissected. Total RNA was extracted, reverse transcribed, and radiolabelled probes were hybridised to an array containing 5,353 genes. Arrays were evaluated by hierarchical cluster analysis and significance analysis of microarrays. RESULTS: 78% of genes were expressed by native RPE while 45.3--47.7% were expressed by ARPE-19 cells, depending on culture condition. While the most abundant genes were expressed by native and cultured cells, significant differences in low abundance genes were seen. Hierarchical cluster analysis showed that confluent and differentiated, serum withdrawn cultures clustered closest to native RPE, and that serum segregated cultured cells from native RPE. The number of differentially expressed genes and their function, and profile of expressed and unexpressed genes, demonstrate differences between native and cultured cells. CONCLUSIONS: While ARPE-19 cells have significant value for studying RPE behaviour, investigators must be aware of how culture conditions can influence the mRNA phenotype of the cell.

Platelet-activating factor induces a concentration-dependent spectrum of functional responses in bovine neutrophils.

We characterized the dose response of bovine neutrophils to platelet-activating factor (PAF) with respect to the following functions: calcium flux and membrane potential changes, actin polymerization, degranulation, and the production and/or priming of the oxidative burst. PAF at very low concentrations (10(-10) and 10(-9) M) caused changes in intracellular calcium and membrane potential in bovine neutrophils, whereas moderate PAF concentrations (> or = 10(-7) M) resulted in increased actin polymerization. Degranulation responses to PAF were more complex: low concentrations (10(-9) M) caused secretory granule degranulation, moderate doses (> or = 10(-7) M) caused specific granule degranulation, whereas azurophil degranulation only occurred at high (10(-5) M) PAF concentrations. Treatment of bovine neutrophils with PAF at concentrations > or = 10(-7) M also caused up-regulation of the adhesion molecules Mac-l and L-selectin. PAF stimulation resulted in a very weak [compared to phorbol myristate acetate (PMA)] oxidative burst in bovine neutrophils, and only at high (10(-6) M) concentrations. Unlike human neutrophils, bovine neutrophils were poorly primed by PAF treatment. Only high concentrations of PAF (10(-5) M) caused an increased rate of PMA-stimulated superoxide production, although lower doses of PAF did reduce the lag time preceding the PMA-induced oxidative burst. The overall pattern that can be inferred is that lower concentrations of PAF promote neutrophil sensitivity and interaction by selective degranulation, up-regulation of adhesion molecules, and increased actin polymerization. In contrast, higher PAF concentrations can promote, albeit weakly, more direct bactericidal responses, such as the release of reactive oxygen species and granule enzymes. The ability of PAF to modulate a graded response in bovine neutrophils would allow the cell to respond proportionally to the severity of a stimulus.

A systematic methodology to estimate added sugar content of foods.

BACKGROUND/OBJECTIVES: The effect of added sugar on health is a topical area of research. However, there is currently no analytical or other method to easily distinguish between added sugars and naturally occurring sugars in foods. This study aimed to develop a systematic methodology to estimate added sugar values on the basis of analytical data and ingredients of foods. SUBJECTS/METHODS: A 10-step, stepwise protocol was developed, starting with objective measures (six steps) and followed by more subjective estimation (four steps) if insufficient objective data are available. The method developed was applied to an Australian food composition database (AUSNUT2007) as an example. RESULTS: Out of the 3874 foods available in AUSNUT2007, 2977 foods (77%) were assigned an estimated value on the basis of objective measures (steps 1-6), and 897 (23%) were assigned a subjectively estimated value (steps 7-10). Repeatability analysis showed good repeatability for estimated values in this method. CONCLUSIONS: We propose that this method can be considered as a standardised approach for the estimation of added sugar content of foods to improve cross-study comparison.

Genetic and transcriptional organization of the Bacillus subtilis spc-alpha region.

We used chromosomal walking methods to isolate a 10.8-kb region from the major ribosomal protein (r-protein) gene cluster of Bacillus subtilis (Bs). The gene order in this region, given by gene product, was r-proteins L16-L29-S17-L14-L24-L5-S14-S8-L6-L18-S5-L30-L15-SecY-adenylate kinase (Adk)-methionine aminopeptidase (Map)-initiation factor 1 (IF1)-L36-S13-S11-alpha subunit of RNA polymerase-L17. The region cloned, therefore, contains the homologues for the last three genes of the Escherichia coli (Ec) S10 operon, together with entire spc and alpha operons. This Bs organization differs from the corresponding region in Ec by the inclusion of the genes encoding Adk, Map and IF1 between the genes encoding SecY and L36. Plasmid integration experiments indicated that all 22 genes comprise a single large transcriptional unit controlled from a major promoter which lies upstream from the gene encoding r-protein L16. Promoter probe experiments located lesser activities internal to this large transcriptional unit, the secY and map promoters. The secY promoter region (psecY) contained two activities, each principally functioning in the stationary growth phase when high protein export is required. Thus, the Bs S10-spc-alpha region differs from its Ec counterpart in both genetic and transcriptional organization. Given this difference in transcriptional organization, the mechanisms coordinating expression of the translational apparatus are also likely to differ between Ec and Bs.

Cryopreservation of rabbit corneas in dimethyl sulfoxide.

PURPOSE: To minimize the injury to endothelial cells during cryopreservation of rabbit corneas with dimethyl sulfoxide. METHODS: Rabbit corneas were cryopreserved using 20% wt/wt dimethyl sulfoxide (Me2SO), added and removed in stages to maintain the osmotically induced excursions in cell volume to within +/-40% of their isotonic volume. The vehicle solution, cooling rate, and conditions of storage used were those already reported to be optimal for endothelial cell survival after exposure to low temperatures. Survival was assessed by confocal microscopy with vital staining and by the ability of the endothelium to control stromal hydration during 3 hours of normothermic perfusion. The effect of temperature of addition and removal of Me2SO (room temperature [RT] or 2 degrees C) on endothelial viability also was measured. RESULTS: After thawing, all the cryopreserved corneas appeared structurally intact when assessed by vital staining and could limit stromal swelling during subsequent normothermic perfusion. Analysis of the rate of stromal swelling during the first 1.5 hours of normothermic perfusion indicated a substantial benefit when the Me2SO was removed at RT. Adding and removing the Me2SO at RT, which allowed a briefer exposure to Me2SO before cooling, resulted in better structural integrity of the endothelial layer than when the addition of cryoprotectant took place on ice. CONCLUSIONS: These results demonstrate the importance of osmotic stresses in the generation of injury to corneal endothelium during cryopreservation and the possibility of eventual successful cryopreservation of this tissue.

Consumer response to healthy eating, physical activity and weight-related recommendations: a systematic review.

Strong evidence linking poor diet and lack of physical activity to risk of obesity and related chronic disease has supported the development and promotion of guidelines to improve population health. Still, obesity continues to escalate as a major health concern, and so the impact of weight-related guidelines on behaviour is unclear. The aim of this review was to examine consumer response to weight-related guidelines. A systematic literature search was performed using Medline, PsycInfo, ProQuest Central and additional searches using Google and reference lists. Of the 1,765 articles identified, 46 relevant titles were included. Most studies examined attitudes towards content, source, tailoring and comprehension of dietary guidelines. Many respondents reported that guidelines were confusing, and that simple, clear, specific, realistic, and in some cases, tailored guidelines are required. Recognition of guidelines did not signify understanding nor did perceived credibility of a source guarantee utilization of guidelines. There was a lack of studies assessing: the impact of guidelines on behaviour; responses to physical activity guidelines; responses among males and studies undertaken in developing countries. Further research is needed, in particular regarding responses to physical activity guidelines and guidelines in different populations. Communication professionals should assist health professionals in the development of accurate and effective weight-related guidelines.

L-threonine dehydrogenase. Purification and properties of the homogeneous enzyme from Escherichia coli K-12.

L-Threonine dehydrogenase, which catalyzes the conversion of L-threonine to aminoacetone + CO2 presumably via the intermediate formation of alpha-amino-beta-ketobutyrate, has been purified to apparent homogeneity from extracts of a mutant of Escherichia coli K-12 which has constitutively derepressed levels of the enzyme. Three fractionation steps were used including controlled heat denaturation, DEAE-Sephadex chromatography, and blue dextran-Sepharose affinity chromatography. The purified enzyme migrated as a single band, coincident with dehydrogenase activity, when electrophoresed on polyacrylamide gels at pH 8.0 and 9.5. Electrophoresis in 1% sodium dodecyl sulfate also showed one band and a single schlieren peak was seen during sedimentation velocity centrifugation. The enzyme has an apparent molecular weight of 140,000 +/- 4,000 as determined by sucrose density and sedimentation equilibrium centrifugation. Based on electrophoresis in 1% sodium dodecyl sulfate, sedimentation equilibrium centrifugation in 6 M guanidine.HCl, and cross-linking with dimethyl suberimidate, the molecule is a tetramer consisting of identical (or nearly identical) subunits with Mr approximately equal to 35,000. L-Threonine dehydrogenase is specific for NAD+ or NAD+ analogs and utilizes L-threonine, D-allothreonine, or L-threonine amide as the best substrates. In 50 mM Tris.HCl buffer (pH 8.4) and 37 degrees C, the Km values for L-threonine and NAD+ are 1.43 and 0.19 mM, respectively. The enzyme has a pH optimum of 10.3, is activated by Mn2+, and shows a substantial loss of activity when treated with certain sulfhydryl-reacting reagents.

Growth, enzyme levels, and some metabolic properties of an Escherichia coli mutant grown on L-threonine as the sole carbon source.

A mutant of Escherichia coli (designated E. coli SBD-76) that utilizes L-threonine as the sole carbon source was isolated. In contrast with levels in extracts of wild-type cells, the levels of threonine dehydrogenase in extracts of this mutant were 100-fold higher than levels of threonine aldolase or degradative threonine dehydratase. Catabolite repression of threonine dehydrogenase was manifested in wild-type, but not SBD-76, cells. For purposes of isolating enzymes, large quantities of SBD-76 cells with the elevated threonine dehydrogenase level could be grown in a fermentor in modified Fraser medium containing 1% glycerol, rather than in the 0.2% L-threonine minimal medium used to isolate the mutant. SBD-76 cells grown on L-threonine excreted glycine and aminoacetone into the medium, and extracts of the mutant strain catalyzed a quantitative conversion of L-threonine to glycine and aminoacetone.

Testicular seminoma: effectiveness of primary radiation therapy.

We retrospectively studied 44 patients with testicular seminoma treated with primary radiation therapy at the Bowman Gray School of Medicine from 1972 through 1982. The 26 patients with stage I disease received infradiaphragmatic irradiation. Eleven of the 12 with stage II disease, the three with stage III disease, and three with retroperitoneal disease received irradiation to the mediastinum and infradiaphragmatic area. The three-year survival rate without evidence of disease was 100% for stage I. For stage II, the rate was 92% with radiation therapy alone and 100% with salvage therapy. In two patients with stage III disease radiation therapy failed, but both had bulky abdominal disease. Only one died of seminoma. One of the patients with retroperitoneal tumor had unsuccessful radiation therapy but was salvaged with chemotherapy. Neither the diagnosis of anaplastic seminoma in nine patients nor elevated preorchiectomy beta-HCG levels in four patients affected their prognosis. In our series, primary radiation therapy with proper salvage therapy yielded 98% survival.

Recurrent meningioma.

Single meningiomas are histologically classified as benign tumors, but clearly malignant types have been encountered. The standard mode of management is total macroscopic removal with excision of the dural attachment and abnormal bone, if there is any. Despite this aggressive surgery, recurrence rates of approximately 9% have been reported with the removal of benign tumors, and the rate is much higher with the removal of malignant meningiomas. Recurrence most frequently occurs at the original tumor site and is most often explained by incomplete removal, which, in turn, is a function of the anatomic location of the tumor. Less common are regional recurrences, which may be explained on the basis of the multicentric origin of meningiomas. This theory may also explain the rare entity, "multiple meningioma." This article documents an unexpected regional recurrence of meningioma. The pertinent literature is reviewed.