Self-monitoring has no adverse effect on disordered eating in adults seeking treatment for obesity

OBJECTIVES

Although monitoring is considered a key component of effective behaviour change, the development of apps has allowed consumers to constantly evaluate their own diet, with little examination of what this might mean for eating behaviour. The aim of this study was to investigate whether self-monitoring of diet using the app MyFitnessPal or daily self-weighing increases the reported occurrence of eating disorders in adults with overweight/obesity following a weight loss programme.

METHODS

Two hundred fifty adults with body mass index ≥ 27 kg/m2 received diet and exercise advice and were randomized to one of four monitoring strategies (daily self-weighing, MyFitnessPal, brief monthly consults or self-monitoring hunger) or control for 12 months. The Eating Disorder Examination Questionnaire 6.0 was used to assess eating disorder symptoms and behaviours for the previous 28 d at 0 and 12 months.

RESULTS

There were no significant differences in the global Eating Disorder Examination Questionnaire score or the subscales between those in the four monitoring groups and the control at 12 months (all p ≥ 0.164), nor were there differences in binge eating, self-induced vomiting, laxative misuse or excessive exercise at 12 months (p ≥ 0.202). The overall prevalence of one or more episodes of binge eating was 53.6% at baseline and 50.6% at 12 months, with no change over time (p = 0.662).

CONCLUSIONS

There was no evidence that self-monitoring, including using diet apps like MyFitnessPal or daily self-weighing, increases the reported occurrence of eating disorder behaviours in adults with overweight/obesity who are trying to lose weight.

Faraday-Shielded dc Stark-Shift-Free Optical Lattice Clock

We demonstrate the absence of a dc Stark shift in an ytterbium optical lattice clock. Stray electric fields are suppressed through the introduction of an in-vacuum Faraday shield. Still, the effectiveness of the shielding must be experimentally assessed. Such diagnostics are accomplished by applying high voltage to six electrodes, which are grounded in normal operation to form part of the Faraday shield. Our measurements place a constraint on the dc Stark shift at the 10^{-20} level, in units of the clock frequency. Moreover, we discuss a potential source of error in strategies to precisely measure or cancel nonzero dc Stark shifts, attributed to field gradients coupled with the finite spatial extent of the lattice-trapped atoms. With this consideration, we find that Faraday shielding, complemented with experimental validation, provides both a practically appealing and effective solution to the problem of dc Stark shifts in optical lattice clocks.

#cutting: Non-suicidal self-injury (NSSI) on Instagram

BACKGROUND

Social media presents an important means for social interaction, especially among adolescents, with Instagram being the most popular platform in this age-group. Pictures and communication about non-suicidal self-injury (NSSI) can frequently be found on the internet.

METHODS

During 4 weeks in April 2016, n = 2826 (from n = 1154 accounts) pictures which directly depicted wounds on Instagram were investigated. Those pictures, associated comments, and user accounts were independently rated for content. Associations between characteristics of pictures and comments as well as weekly and daily trends of posting behavior were analyzed.

RESULTS

Most commonly, pictures depicted wounds caused by cutting on arms or legs and were rated as mild or moderate injuries. Pictures with increasing wound grades and those depicting multiple methods of NSSI generated elevated amounts of comments. While most comments were neutral or empathic with some offering help, few comments were hostile. Pictures were mainly posted in the evening hours, with a small peak in the early morning. While there was a slight peak of pictures being posted on Sundays, postings were rather evenly spread across the week.

CONCLUSIONS

Pictures of NSSI are frequently posted on Instagram. Social reinforcement might play a role in the posting of more severe NSSI pictures. Social media platforms need to take appropriate measures for preventing online social contagion.

Hyperpolarizability and Operational Magic Wavelength in an Optical Lattice Clock

Optical clocks benefit from tight atomic confinement enabling extended interrogation times as well as Doppler- and recoil-free operation. However, these benefits come at the cost of frequency shifts that, if not properly controlled, may degrade clock accuracy. Numerous theoretical studies have predicted optical lattice clock frequency shifts that scale nonlinearly with trap depth. To experimentally observe and constrain these shifts in an ^{171}Yb optical lattice clock, we construct a lattice enhancement cavity that exaggerates the light shifts. We observe an atomic temperature that is proportional to the optical trap depth, fundamentally altering the scaling of trap-induced light shifts and simplifying their parametrization. We identify an "operational" magic wavelength where frequency shifts are insensitive to changes in trap depth. These measurements and scaling analysis constitute an essential systematic characterization for clock operation at the 10^{-18} level and beyond.

Psychosocial interventions for children and adolescents after man-made and natural disasters: a meta-analysis and systematic review

Children and adolescents are a vulnerable group to develop post-traumatic stress symptoms after natural or man-made disasters. In the light of increasing numbers of refugees under the age of 18 years worldwide, there is a significant need for effective treatments. This meta-analytic review investigates specific psychosocial treatments for children and adolescents after man-made and natural disasters. In a systematic literature search using MEDLINE, EMBASE and PsycINFO, as well as hand-searching existing reviews and contacting professional associations, 36 studies were identified. Random- and mixed-effects models were applied to test for average effect sizes and moderating variables. Overall, treatments showed high effect sizes in pre-post comparisons (Hedges' g = 1.34) and medium effect sizes as compared with control conditions (Hedges' g = 0.43). Treatments investigated by at least two studies were cognitive-behavioural therapy (CBT), eye movement desensitization and reprocessing (EMDR), narrative exposure therapy for children (KIDNET) and classroom-based interventions, which showed similar effect sizes. However, studies were very heterogenic with regard to their outcomes. Effects were moderated by type of profession (higher level of training leading to higher effect sizes). A number of effective psychosocial treatments for child and adolescent survivors of disasters exist. CBT, EMDR, KIDNET and classroom-based interventions can be equally recommended. Although disasters require immediate reactions and improvisation, future studies with larger sample sizes and rigorous methodology are needed.

Differences in Activation and Deactivation in Children with Sickle Cell Disease Compared with Demographically Matched Controls

BACKGROUND AND PURPOSE

Declines in both functional activation and functional connectivity have been reported in patients with sickle cell disease. In this study, we derived the functional and default mode responses to a word stem paradigm in age-, ethnicity-, and background-matched subjects with sickle cell disease and control groups, with the aim of testing whether both networks were similarly attenuated and whether the changes were related to physiologic parameters that characterize sickle cell disease.

MATERIALS AND METHODS

Both the functional and default mode responses were obtained from age- and background-matched controls and the sickle cell population by using a visually presented word stem paradigm on a 3T scanner.

RESULTS

We observed an attenuated response to both activation and deactivation in the sickle cell disease group. There were no significant differences in the activation response between the 2 groups for the contrast control > sickle cell disease; however, significant differences were observed in the medial parietal cortex, the auditory cortex, and the angular gyrus for the default mode. For the sickle cell group, a significant correlation between the activation z scores and the physiologic parameters was observed; for the deactivation, the results were not significant but the trend was similar.

CONCLUSIONS

The results indicate that the physiologic parameters modulate the activation in the expected fashion, but that the effect was weaker for deactivation. Given that significant differences between the 2 groups were only seen for deactivation, additional factors must modulate the deactivation in sickle cell disease.

Anomalous Broadening in Driven Dissipative Rydberg Systems

We observe interaction-induced broadening of the two-photon 5s-18s transition in ^{87}Rb atoms trapped in a 3D optical lattice. The measured linewidth increases by nearly 2 orders of magnitude with increasing atomic density and excitation strength, with corresponding suppression of resonant scattering and enhancement of off-resonant scattering. We attribute the increased linewidth to resonant dipole-dipole interactions of 18s atoms with blackbody induced population in nearby np states. Over a range of initial atomic densities and excitation strengths, the transition width is described by a single function of the steady-state density of Rydberg atoms, and the observed resonant excitation rate corresponds to that of a two-level system with the measured, rather than natural, linewidth. The broadening mechanism observed here is likely to have negative implications for many proposals with coherently interacting Rydberg atoms.

Hyperplastic and Neoplastic Changes in the Lungs of Rats Treated Concurrently with Chrysotile Asbestos and N-Nitrosoheptamethyleneimine

This study investigated the combined effect in rat lungs of simultaneous exposure to chrysotile asbestos and N-nitrosoheptamethyleneimine (NHMI), with the objective of determining the potential for chrysotile to promote or otherwise enhance the pathological responses to this potent rodent lung carcinogen. Groups of 15 or 20 male and female animals were treated with 0, 3, or 10 mg kg(-1) NHMI subcutaneously, once a week for 10 wk, plus either clean air (control) or 50 mg m(-3) chrysotile by nose-only inhalation for 4 wk. A broad range of pulmonary metaplastic, hyperplastic, and neoplastic lesions was observed. Effects were more marked in male than in female animals. NHMI treatment increased the incidence of hyperplastic lesions, with apparent augmentation by chrysotile exposure (not statistically significant). Similarly, a "promoting" effect of chrysotile in the induction of lung tumors was observed, with all but 2 of the 11 primary tumors detected being in animals treated with both NHMI and asbestos. However, this apparent interaction was again not confirmable statistically, probably because of the low number of observed tumors (stemming from premature termination of the experiment). The study results are in line with those of similar previous studies, which found a higher incidence of hyperplastic and neoplastic changes in animals treated with both nitrosamine and asbestos than in those given nitrosamine alone. It is proposed that the method described (with minor modification) could be used to investigate either (1) the ability of other inhaled particles to augment NHMI carcinogenicity, or (2) the propensity of other chemical carcinogens to interact with asbestos in the production of pulmonary neoplasms.

White matter damage in asymptomatic patients with sickle cell anemia: screening with diffusion tensor imaging

BACKGROUND AND PURPOSE

Ischemic injury to the brain is a common complication of SCA. To better understand the neurologic impact of SCA, TBSS were applied to DTI data to investigate white matter injuries in pediatric patients with SCA.

MATERIALS AND METHODS

TBSS comparisons of a range of anisotropy and diffusion measures were carried out between age- and background-matched population groups: patients with SCA with no visible lesions, patients with SCA with mild gliosis, and normal controls.

RESULTS

TBSS analysis revealed that both SCA populations exhibited reduced anisotropy and increased diffusivity compared with normal controls in multiple brain regions, including the corpus callosum and centrum semiovale. Furthermore, the results suggest that the severity of SCA is positively correlated with the white matter changes in the corpus callosum.

CONCLUSIONS

The study demonstrates that TBSS is a viable technique in detecting subtle white matter damage in patients with SCA whose conventional anatomic MR imaging scans show no, or minimal, abnormalities and has the potential to evaluate the neurologic impact of the treatment of SCA.

Optimization of a free-fall reactor for the production of fast pyrolysis bio-oil

A central composite design of experiments was performed to optimize a free-fall reactor for the production of bio-oil from red oak biomass. The effects of four experimental variables including heater set-point temperature, biomass particle size, sweep gas flow rate and biomass feed rate were studied. Heater set-point temperature ranged from 450 to 650 °C, average biomass particle size from 200 to 600 μm, sweep gas flow rate from 1 to 5 sL/min and biomass feed rate from 1 to 2 kg/h. Optimal operating conditions yielding over 70 wt.% bio-oil were identified at a heater set-point temperature of 575 °C, while feeding red oak biomass sized less than 300 μm at 2 kg/h into the 0.021 m diameter, 1.8m tall reactor. Sweep gas flow rate did not have significant effect on bio-oil yield over the range tested.

Process optimization of an auger pyrolyzer with heat carrier using response surface methodology

A 1 kg/h auger reactor utilizing mechanical mixing of steel shot heat carrier was used to pyrolyze red oak wood biomass. Response surface methodology was employed using a circumscribed central composite design of experiments to optimize the system. Factors investigated were: heat carrier inlet temperature and mass flow rate, rotational speed of screws in the reactor, and volumetric flow rate of sweep gas. Conditions for maximum bio-oil and minimum char yields were high flow rate of sweep gas (3.5 standard L/min), high heat carrier temperature (∼600 °C), high auger speeds (63 RPM) and high heat carrier mass flow rates (18 kg/h). Regression models for bio-oil and char yields are described including identification of a novel interaction effect between heat carrier mass flow rate and auger speed. Results suggest that auger reactors, which are rarely described in literature, are well suited for bio-oil production. The reactor achieved liquid yields greater than 73 wt.%.

{gamma}-Tubulin and microtubule organization during meiosis in the liverwort Ricciocarpus natans (Ricciaceae)

Extant liverworts are "living fossils" considered sister to all other plants and as such provide clues to the evolution of the microtubule organizing center (MTOC) in anastral cells. This report is the first on microtubule arrays and their γ-tubulin-nucleating sites during meiosis in a member of the Ricciales, a specialized, species-rich group of complex thalloid (marchantioid) liverworts. In meiotic prophase, γ-tubulin becomes concentrated at several sites adjacent to the nuclear envelope. Microtubules organized at these foci give rise to a multipolar prometaphase spindle. By metaphase I, the spindle has matured into a bipolar structure with truncated poles. In both first and second meiosis, γ-tubulin forms box-like caps at the spindle poles. γ-Tubulin moves from spindle poles to the proximal surfaces of telophase chromosomes where interzonal microtubules are nucleated. Although a phragmoplast is organized, no cell plate is deposited, and second division occurs simultaneously in the undivided sporocyte. γ-Tubulin surrounds each of the tetrad nuclei, and phragmoplasts initiated between both sister and nonsister nuclei direct simultaneous cytokinesis. The overall pattern of meiosis (unlobed polyplastidic sporocytes, nuclear envelope MTOC, multipolar spindle origin, spindles with box-like poles, and simultaneous cytokinesis) more closely resembles that of Conocephalum than other marchantiod liverworts.

Polar organizers and girdling bands of microtubules are associated with gamma-tubulin and act in establishment of meiotic quadripolarity in the hepatic Aneura pinguis (Bryophyta)

Meiosis in Aneura pinguis is preceded by extensive cytoplasmic preparation for quadripartitioning of the diploid sporocyte into a tetrad of haploid spores. In early prophase the four future spore domains are defined by lobing of the cytoplasm and development of a quadripolar prophase spindle focused at polar organizers (POs) centered in the lobes. Cells entering the reproductive phase become isolated and, instead of hooplike cortical microtubules, have endoplasmic microtubule systems centered on POs. These archesporial cells proliferate by mitosis before entering meiosis. In prophase of each mitosis, POs containing a distinct concentration of gamma-tubulin appear de novo at tips of nuclei and initiate the bipolar spindle. Cells entering meiosis become transformed into quadrilobed sporocytes with four POs, one in each lobe. This transition is a complex process encompassing assembly of two opposite POs which subsequently disperse into intersecting bands of microtubules that form around the central nucleus. The girdling bands define the future planes of cytokinesis and the cytoplasm protrudes through the restrictive bands becoming quadrilobed. Two large POs reappear in opposite cleavage furrows. Each divides and the resulting POs migrate into the tetrahedral lobes of cytoplasm. Cones of microtubules emanating from the four POs interact to form a quadripolar microtubule system (QMS) that surrounds the nucleus in meiotic prophase. The QMS is subsequently transformed into a functionally bipolar metaphase spindle by migration of poles in pairs to opposite cleavage furrows. These findings contribute to knowledge of microtubule organization and the role of microtubules in spatial regulation of cytokinesis in plants.

Peripheral-type benzodiazepine receptor in neurosteroid biosynthesis, neuropathology and neurological disorders

The peripheral-type benzodiazepine receptor is a mitochondrial protein expressed at high levels in steroid synthesizing tissues, including the glial cells of the brain. Peripheral-type benzodiazepine receptor binds cholesterol with high affinity and is a key element of the cholesterol mitochondrial import machinery responsible for supplying the substrate cholesterol to the first steroidogenic enzyme, thus initiating and maintaining neurosteroid biosynthesis. Neurosteroid formation and metabolism of steroid intermediates are critical components of normal brain function. Peripheral-type benzodiazepine receptor also binds with high affinity various classes of compounds. Upon ligand activation peripheral-type benzodiazepine receptor-dependent cholesterol transport into mitochondria is accelerated leading in increased formation of neuroactive steroids. These steroids, such as allopregnanolone, have been shown to be involved in various neurological disorders, such as anxiety and mood disorders. Thus, peripheral-type benzodiazepine receptor drug ligand-induced neuroactive steroid formation offers a means to regulate brain dysfunction. Peripheral-type benzodiazepine receptor basal expression is upregulated in a number of neuropathologies, including gliomas and neurodegenerative disorders, as well as in various forms of brain injury and inflammation. In Alzheimer's disease pathology neurosteroid biosynthesis is altered and a decrease in the intermediate 22R-hydroxycholesterol levels is observed. This steroid was found to exert neuroprotective properties against beta-amyloid neurotoxicity. Based on this observation, a stable spirostenol derivative showing to display neuroprotective properties was identified, suggesting that compounds developed based on critical intermediates of neurosteroid biosynthesis could offer novel means for neuroprotection. In conclusion, changes in peripheral-type benzodiazepine receptor and neurosteroid levels are part of the phenotype seen in neuropathology and neurological disorders and offer potential targets for new therapies.

Adsorption of arsenic(V) by activated carbon prepared from oat hulls

The efficiency of self-manufactured activated carbon (AC) produced from oat hulls in adsorbing arsenic(V) was tested in a batch reactor. The results indicated that the adsorptive capacity of AC was affected by initial pH value, with adsorption capacity decreasing from 3.09 to 1.57 mg As g(-1) AC when the initial pH values increased from 5 to 8. A modified linear driving force model conjugated with a Langmuir isotherm was created to describe the study's kinetics. The test results show that rapid adsorption and slow adsorption exist simultaneously when AC is used to remove arsenic(V).

Gamma-tubulin and microtubule organization during microsporogenesis in Ginkgo biloba

This is the first report on gamma-tubulin and microtubule arrays during microsporogenesis in a gymnosperm. Meiosis in Ginkgo biloba is polyplastidic, as is typical of the spermatophyte clade, and microtubule arrays are organized at various sites during meiosis and cytokinesis. In early prophase, a cluster of gamma-tubulin globules occurs in the central cytoplasm adjacent to the off-center nucleus. These globules diminish in size and spread over the surface of the nucleus. A system of microtubules focused on the gamma-tubulin forms a reticulate pattern in the cytoplasm. As the nucleus migrates to the center of the microsporocyte, gamma-tubulin becomes concentrated at several sites adjacent to the nuclear envelope. Microtubules organized at these foci of gamma-tubulin give rise to a multipolar prophase spindle. By metaphase I, the spindle has matured into a distinctly bipolar structure with pointed poles. In both first and second meiosis, gamma-tubulin becomes distributed throughout the metaphase spindles, but becomes distinctly polar again in anaphase. In telophase I, gamma-tubulin moves from polar regions to the proximal surface of chromosome groups/nuclei where interzonal microtubules are organized. No cell wall is deposited and the interzonal microtubules embrace a plate of organelles between the two nuclear cytoplasmic domains (NCDs) of the dyad. Following second meiosis, phragmoplasts that form between sister and non-sister nuclei fuse to form a complex six-sided structure that directs simultaneous cytokinesis. Gamma-tubulin becomes associated with nuclei after both meiotic divisions and is especially conspicuous in the distal hemisphere of each young microspore where an unusual encircling system of cortical microtubules develops.

Economic analysis of selected lignocellulose-to-ethanol conversion technologies

The objective of this case study was to examine the economics of three lignocellulose-to-ethanol conversion technologies: fast pyrolysis integrated with a fermentation step, simultaneous saccharification and fermentation (SSF), and dilute sulfuric acid hydrolysis and fermentation. All technologies were assumed to have an annual production rate of 25 million gallons of ethanol. The three technologies were compared in terms of capital costs, operating costs, and ethanol production costs. Sensitivity analyses were carried out to study the uncertainties of wood costs and ethanol production rates on ethanol production costs. Final economic analysis showed that fast pyrolysis integrated with a fermentation step is comparable with the other two processes and suggests that it should be considered for further development.

Survey of the biological effects of refractory ceramic fibres: overload and its possible consequences

This paper summarizes the biological effects of refractory ceramic fibres (RCFs). RCFs are aluminosilicate glass insulation wools with similar chemical properties to other synthetic vitreous fibres (SVFs) or 'man-made vitreous fibres' (MMVFs). There is concern that RCFs could be significantly more pathogenic than other SVFs. This paper critically reviews the data on which this perception is based. Morbidity studies on workers in RCF manufacturing indicated that, in the United states, RCF exposure was associated with an increased incidence of pleural plaques and in both the united states and Europe with statistically significant changes in some measures of lung function (though not at present exposure levels). No interstitial fibrosis was found. An ongoing mortality study of limited statistical power has failed to indicate any increased incidence of lung cancer or mesothelioma. Findings in several early animal studies led to a large series of inhalation studies where rats exposed to high levels of RCF developed fibrosis and tumours but not those exposed to other SVFs. Similarly hamsters exposed to one sample (RCF1) developed mesothelioma. Subsequent analyses of the data indicated that the RCF used in these experiments had a significantly greater proportion of non-fibrous particles than those present in the other types of SVFs tested or in workplace air. Short-term studies indicated that pulmonary overload occurred at the same as RCF tissue burdens as those in the long-term animal bioassay. When RCFs were prepared in the same way as the other SVFs, a sample resulted with a more representative ratio of particles to fibres; this sample did not produce overload in short-term tests. SVFs have various abilities to persist in the lung tissue and thus accumulate to varying degrees. It is suggested that biopersistence is a key property. While RCFs are among the more persistent they are similar to many other fibre types. The scientific and regulatory implications of these findings are examined.

Gamma-tubulin localization changes from discrete polar organizers to anastral spindles and phragmoplasts in mitosis of Marchantia polymorpha L

Unlike the astral mitotic spindle that is organized at discrete centriolar centrosomes, the spindle of land plants is typically anastral and its origin has remained obscure. Gamma tubulin (gamma-tubulin), an important component of the centrosome, has been demonstrated at microtubule-nucleating sites in plant cells. Mitotic spindles of certain hepatics are initiated at distinct acentriolar polar organizers (POs) that appear de novo at the onset of mitosis. Data on the relationship of gamma-tubulin to POs and to microtubule arrays throughout the cell cycle were collected from rapidly dividing cells of Marchantia polymorpha (Bryophyta) that were triple-stained for gamma-tubulin, microtubules, and nuclei. POs at opposite ends of the elongated nucleus in early prophase stain brightly for gamma-tubulin and astral microtubules emanating from them initiate the spindle. As the spindle develops, however, the gamma-tubulin becomes dispersed from the highly concentrated spherical form of the POs to more diffusely organized cups at tips of the fusiform nucleus. By the end of prophase, all astral microtubules have disappeared and the gamma-tubulin is located in several minipoles along the now broad polar regions of the spindle. At metaphase, gamma-tubulin extends into the spindle itself. By telophase, the gamma-tubulin has migrated from distal to proximal surfaces of the sister nuclei and extends into the phragmoplast. Upon completion of cytokinesis, gamma-tubulin appears diminished and surrounds the nuclear envelopes. These data show that gamma-tubulin is only briefly concentrated in the PO, migrates in a cell-cycle-specific manner, and is consistently present at all putative sites of microtubule nucleation.

Steam activation of chars produced from oat hulls and corn stover

Oat hulls and corn stover were used to produce chars at approximately 500 degrees C. The carbon concentrations of oat hull char and corn stover chars produced were 72.3 and 68.0 wt.%, respectively. Both activation burn-off and Brunauer-Emmett-Teller (BET) surface area appear to exhibit a linear relationship with respect to activation time of oat hulls. As to corn stover activated carbons, there is no linear relationship between activation time and BET surface area. However, activation burn-off of and activation time appear to relate in a linear manner for the activated carbons produced from corn stover chars. Oat hull is better than corn stover as a raw material for the production of activated carbon.

Application of thermophilic enzymes in commercial biotransformation processes

Biocatalysis is a useful tool in the provision of chiral technology and extremophilic enzymes are just one component in that toolbox. Their role is not always attributable to their extremophilic properties; as with any biocatalyst certain other criteria should be satisfied. Those requirements for a useful biocatalyst will be discussed including issues of selectivity, volume efficiency, security of supply, technology integration, intellectual property and regulatory compliance. Here we discuss the discovery and commercialization of an l-aminoacylase from Thermococcus litoralis, the product of a LINK project between Chirotech Technology and the University of Exeter. The enzyme was cloned into Escherichia coli to aid production via established mesophilic fermentation protocols. A simple downstream process was then developed to assist in the production of the enzyme as a genetically modified-organism-free reagent. The fermentation and downstream processes are operated at the 500 litre scale. Characterization of the enzyme demonstrated a substrate preference for N-benzoyl groups over N-acetyl groups. The operational parameters have been defined in part by substrate-concentration tolerances and also thermostabilty. Several examples of commercial biotransformations will be discussed including a process that is successful by virtue of the enzyme's thermotolerance.

A dose-response model for refractory ceramic fibers

Refractory ceramic fibers (RCFs) are man-made vitreous fibers commonly used in insulation applications above 1000 degrees C. Although they have been subjected to considerable toxicologic evaluation, only the pooled results from two rat inhalation studies provide data that may be suitable for performing a numerical risk assessment. Even in these inhalation studies, good evidence exists that the maximum tolerated dose (MTD) was exceeded and that pulmonary overload occurred, a condition that will cause tumors whatever the dust responsible. Indeed, a significant yield of tumors was only obtained at the highest dose tested. If these results are omitted, there is no statistically significant evidence of carcinogenicity within the RCF results. Although there is little evidence that overload-related tumors are relevant to human risk, we adopted a conservative approach to obtain the estimates of risk regardless of overload, using a biologically based model, the two-stage clonal expansion model, as well as various statistical models, including the benchmark dose model. We argue that the data favor the use of a biologically based model, which gives the best fit when the highest dose RCF exposures are omitted. Continuing with this model, we show that available data from the RCF experiment, less outliers, coupled with results from other experiments with man-made mineral fibers (MMVFs), demonstrate that all MMVFs are potentially carcinogenic, with any risk mediated by the fibers' biopersistence. Application of this "all MMVF data set" model yields a maximum likely estimate for RCF excess unit risk of 4.6 x 10(-5) (95% upper confidence limit = 9.2 x 10(-5) per fiber/ml). This implies that the risk from occupational exposure to RCFs at 1 fiber/ml for a typical working lifetime would not exceed 10(-4).

TETRASPORE encodes a kinesin required for male meiotic cytokinesis in Arabidopsis

A key step in pollen formation is the segregation of the products of male meiosis into a tetrad of microspores, each of which develops into a pollen grain. Separation of microspores does not occur in tetraspore (tes) mutants of Arabidopsis thaliana, owing to the failure of male meiotic cytokinesis. tes mutants thus generate large 'tetraspores' containing all the products of a single meiosis. Here, we report the positional cloning of the TES locus and details of the role played by the TES product in male cytokinesis. The predicted TES protein includes an N-terminal domain homologous to kinesin motors and a C-terminus with little similarity to other proteins except for a small number of plant kinesins. These include the Arabidopsis HINKEL protein and NACK1 and two from tobacco (Nishihama et al., 2002), which are involved in microtubule organization during mitotic cytokinesis. Immunocytochemistry shows that the characteristic radial arrays of microtubules associated with male meiotic cytokinesis fail to form in tes mutants. The TES protein therefore is likely to function as a microtubule-associated motor, playing a part either in the formation of the radial arrays that establish spore domains following meiosis, or in maintaining their stability.

Events during the first four rounds of mitosis establish three developmental domains in the syncytial endosperm of Arabidopsis thaliana

Endosperm begins development as a single fertilized cell that undergoes many rounds of mitosis without cytokinesis resulting in a syncytium. The multinucleate cytoplasm is organized by nucleus-based radial microtubule systems into nuclear-cytoplasmic domains. When microtubules are organized into mitotic spindles, the integrity of the common cytoplasm is maintained by an unaltered network of filamentous actin. The first four rounds of mitosis result in the establishment of three developmental domains within the common cytoplasm. The spindles of the first two rounds of mitosis are oriented parallel to the long axis of the central cell, resulting in four nuclear-cytoplasmic domains in a filamentous arrangement. A switch in spindle orientation occurs in the third round of mitosis; all four spindles are oriented perpendicular to the long axis resulting in eight nuclear-cytoplasmic domains arranged in two adjacent files. Whereas the first three rounds of mitosis are synchronous, the fourth occurs as a wave of successive mitoses that begins at the micropylar pole. By the 16-nuclei stage, differences in nuclear shape, cytoskeletal arrays, and cytoplasmic characteristics mark the differentiation of the syncytium into micropylar, central, and chalazal developmental chambers. Nuclei in the micropylar chamber are fusiform and sheathed by parallel microtubules that flare from their tips, while those in the central and chalazal chambers are spherical. Nuclei in the central chamber are surrounded by radial microtubule systems, while those in the chalaza are enmeshed in a reticulum of microtubules. Whereas the cytoplasm in both micropylar and chalazal chambers is dense and nearly nonvacuolate, the syncytium in the central chamber consists of a single layer of evenly spaced nuclear-cytoplasmic domains surrounding a large central vacuole.

Cytoskeletal organization of the micropylar endosperm in Coronopus didymus L. (Brassicaceae)

The micropylar chamber of the mustard Coronopus didymus is a developmental domain distinct from the contiguous central chamber and the more extreme chalazal chamber. Early in syncytial development the micropylar endosperm surrounding the embryo becomes populated with unusual fusiform to multilobed nuclei. These nuclei are sheathed by unique parallel arrays of microtubules that focus at tips of the nuclei and flare to connect with a reticulate network in the common cytoplasm. F-actin does not closely invest the nuclei but instead forms an extensive but separate cytoplasmic reticulum. When the embryo is in the early heart stage, the cytoskeleton of the endosperm undergoes a remarkable transition in preparation for cellularization. Microtubules become reorganized into radial arrays emanating from the nuclei, which themselves become spherical. Radial microtubule systems (RMSs), which replace both the parallel microtubules and the cytoplasmic reticulum, organize the common cytoplasm into evenly spaced nuclear cytoplasmic domains (NCDs). F-actin gradually becomes coaligned with the RMSs. Phragmoplasts are initiated adventitiously at the interfaces of opposing RMSs in the absence of mitosis. Cell plate deposition, which is initiated at multiple sites, results in a network of walls formed more or less simultaneously around the densely packed NCDs. The walls, which are rich in 1-3-beta-glucans, join with one another and with the existing walls of both the central cell and embryo to complete cellularization in the micropylar chamber. In the adjacent central chamber where the syncytium is restricted to a thin peripheral layer by the large central vacuole, basic organization of the syncytium into NCDs is followed by alternating cycles of alveolation and periclinal cell division resulting in cellularization.

Role of the peripheral-type benzodiazepine receptor in adrenal and brain steroidogenesis

The peripheral-type benzodiazepine receptor (PBR) has been demonstrated to be critical for steroidogenesis in all steroid-producing tissues. Here, we review the identification and characterization of the PBR, the evidence pointing to its function as a cholesterol pore involved in transporting cholesterol from the cytoplasm of steroid-producing cells into the inner mitochondrial membrane where it is metabolized, and the known mechanisms regulating its function. We present data on the functions of the PBR in the adrenal gland, a classical steroidogenic tissue, and in the brain, which has only recently been proven to be steroidogenic. Finally, we discuss other potential roles for the PBR in pathological conditions, including cancer, neurodegeneration, and neurotoxicity, and a broader role for the PBR in mediating intracellular cholesterol transport/compartmentalization, which may or may not be linked to steroid biosynthesis.

C-H insertion approach to the synthesis of endo,exo-furofuranones: synthesis of (+/-)-asarinin, (+/-)-epimagnolin A, and (+/-)-fargesin

A series of novel 5-aryl-4-aryloxymethyl-3-diazotetrahydrofuran-2-ones (12, 24, and 35a/b) have been prepared and found to undergo regio- and stereoselective C-H insertion reactions to afford 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane-8-ones (18, 26, and 36a/b) with endo,exo stereochemistry. Subsequent reduction of the lactone ring and cyclization of the resulting diols 27 and 37a/b permitted the synthesis of three endo,exo-furofuran lignans: asarinin (2), fargesin (3), and epimagnolin A (4). En route to the key diazo compounds 24 and 35a/b, a modified procedure for the Ghosez keteniminium-olefin cyclization was developed, which was required to minimize the decomposition of acid-sensitive functional groups such as electron-rich benzylic ethers that were present in the target compounds 2-4.

Effects of nonfibrous particles on ceramic fiber (RCF1) toxicity in rats

In previous investigations a reference test sample of prepared ceramic fibers called RCF1 induced lung tumors in a 2-yr inhalation study in rats. It was hypothesized that nonfibrous particles in RCF1 may have played a significant role. The objective of the present study was to compare lung retention and biological effects of another sample of ceramic fibers, called RCF1a, to the original RCF1. The main difference between these 2 samples was the content of nonfibrous particles: 25% of the mass of RCF1 versus 2% for RCF1a. These nonfibrous particles were chemically identical to the fibers. Female Wistar rats were exposed 6 h/day, 5 days/wk for 3 wk to either RCF1a or RCF1 fiber aerosol at a concentration of about 125 fibers (>20 microm long)/ml. Because of differences in the nonfibrous particle contents, the average gravimetric aerosol concentration differed between the two samples (RCF1, 51.2 mg/m(3); RCF1a, 25.8 mg/m(3)). The posttreatment observation period was 12 mo. Biological effects measured include the clearance function of alveolar macrophages (clearance of fibers and tracer particles), and inflammation and its persistence during the recovery period. Alveolar clearance of tracer particles ((46)Sc(2)O(3)) was barely retarded after RCF1a exposure (80 days clearance half-time compared to 60 days in controls). After RCF1 exposure, however, a severe retardation of clearance was observed (1200 vs. 66 days). In both groups, differential cell counts on pulmonary lavage showed a significant increase of polymorphonuclear leukocytes (PMNs) (about 15%) and lymphocytes 3 days after the end of exposure. The PMN influx persisted longer after exposure to RCF1 than RCF1a. The conclusion of the study is that the particle fraction of RCF1 significantly enhanced any adverse effects. This clearly demonstrates the importance of the physical characteristics of the test material for the degree of toxic effects to be expected. The presence of nonfibrous particulates can enhance the effects on the lung of a mixture of fibrous and nonfibrous particulates following exposure.

Filtration in industrial hygiene

Filters used in industrial hygiene are of two basic types, corresponding with the two basic airborne hazards: particulate and vapor. They are as different in their construction as they are in their purpose, and each gives negligible protection against the other hazard. By use of the correct type, adequate filtration efficiency can usually be achieved. Most particulate filters are made from fibers, and finer fibers result in higher efficiency. Filters can capture particles much smaller than the fiber diameter, as a result of diffusional motion of the airborne particles and, in the case of filters that hold a permanent electric charge, electrostatic attraction. Most vapor filters are made from granules of activated carbon, which have an extremely large effective surface area, where molecules of contaminant are adsorbed. The performance of all filters tends to alter as the filter material becomes loaded. Electrically neutral particulate filters become more efficient but at the expense of increased resistance to airflow. Particulate filters that act by electric forces may become less efficient, and are often less inclined to clog. Vapor filters usually have a high initial efficiency, but the penetration of vapor increases as the filters become saturated with adsorbed vapor, and the performance of these filters is normally expressed in terms of their lifetime rather than their efficiency. It is important that the choice of a filter should be made with close reference to the situation in which it is to be used, and optimum respiratory protection should be sought, rather than maximum filtration efficiency. Special problems of filters are illustrated by some case histories, and finally the use of filters as size selectors for dust samplers is briefly described.

Biopersistence, fiber length, and cancer risk assessment for inhaled fibers

We briefly review the evidence that the carcinogenic risk posed by inhaled fibers depends principally on the lung burden of long fibers. We use a deposition clearance model to generate time-dependent lung burdens in rats of a dozen long fibers for various exposure concentrations. Together with a previously estimated potency factor for long fibers, we use the generated lung burdens to estimate risks of lung cancer associated with inhaled fibers in rats. Over a broad range of exposure concentrations, excess risk is a linear function of exposure concentration. Excess risk of lung cancer is also a linear function of weighted half-life for fibers for which the weighted half-life is short compared to the life span of the rat. We propose an approach to estimating human lung cancer risk associated with inhaled fibers from animal studies.

Do untreated bednets protect against malaria?

Bednets are thought to offer little, if any, protection against malaria, unless treated with insecticide. There is also concern that the use of untreated nets will cause people sleeping without nets to receive more mosquito bites, and thus increase the malaria risk for other community members. Regular retreatment of nets is therefore viewed as critical for malaria control. However, despite good uptake of nets, many control programmes in Africa have reported low re-treatment rates. We investigated whether untreated bednets had any protective benefit (in October and November 1996) in The Gambia where nets, although widely used, are mostly untreated. Cross-sectional prevalence surveys were carried out in 48 villages and the risk of malaria parasitaemia was compared in young children sleeping with or without nets. Use of an untreated bednet in good condition was associated with a significantly lower prevalence of Plasmodium falciparum infection (51% protection [95% CI 34-64%], P < 0.001). This finding was only partly explained by differences in wealth between households, and children in the poorest households benefited most from sleeping under an untreated net (62% protection [14-83%], P = 0.018). There was no evidence that mosquitoes were diverted to feed on children sleeping without nets. These findings suggest that an untreated net, provided it is in relatively good condition, can protect against malaria. Control programmes should target the poorest households as they may have the most to gain from using nets.

Structure, function and regulation of the mitochondrial peripheral-type benzodiazepine receptor

Steroid biosynthesis begins with the transfer of cholesterol from intracellular stores into mitochondria. Through in vitro and in vivo studies using various steroidogenic cell models and with the help of pharmacological, biochemical, morphological and molecular approaches we demonstrated that the peripheral-type benzodiazepine receptor (PBR) is an 18 kDa mitochondrial protein that interacts with other proteins in the outer mitochondrial membrane to form a multimeric complex. PBR is required for the binding, uptake and release, upon ligand activation, of the substrate cholesterol. Thus, cholesterol becomes available to the inner mitochondrial membrane P450scc where steroid biosynthesis begins. The presence of mitochondrial PBR is also critical in maintaining outer mitochondrial membrane stability and in preventing apoptosis. Considering these functions of PBR and the fact that PBR is a ubiquitous protein, it is suggested that this drug receptor may serve as a target to control various mitochondrial and cell functions and to protect against experimentally or pathologically induced mitochondrial and cell toxicity.

Long man-made fibers and lung cancer risk

We show that available experimental data from long-term oncogenicity experiments in Fisher rats are consistent with the hypothesis that the oncogenic potential of long man-made mineral fibers is determined mainly by their biopersistence. We present analyses of these data within the initiation-promotion-progression paradigm of carcinogenesis. Our method of analysis can take the temporal pattern of the burden of long fibers in the lungs of individual animals into explicit account. For this analysis, the temporal pattern of lung burden for each animal was imputed from the information obtained from sacrificed animals. The data are consistent with the hypothesis that fibers act as initiators in the rat lung. We present an estimate of the dose-dependent initiation parameter that is based on all the available data.

Dustiness of different high-temperature insulation wools and refractory ceramic fibres

Recent regulations are encouraging the replacement of older types of man-made mineral fibre by more soluble and, thus, less biopersistent compositions. In order for there to be any health benefits from this policy and to gain maximum benefit from such substitutions, the use of the new materials should not increase exposure. The work reported here was undertaken to investigate the use of new high-temperature glass insulation wools in place of refractory ceramic fibres (RCF). Airborne fibre levels occurring during the manufacture of both RCF and calcium magnesium silicate wools (CMS) were compared using measurements of genuine workplace exposure from a routine monitoring operation on the same plant. Exposures during use were compared in one customer facility where RCF and CMS blankets were used for the same task. Further comparisons were made in a laboratory test of dustiness using a "shaking box test". For some manufacturing tasks there are only a few workplace samples and there are few opportunities for genuine comparisons with both RCF and CMS in identical uses. However, both materials produced very similar exposure levels during manufacture, use and in the laboratory test. The novel magnesium silicate fibre was significantly dustier in the laboratory test.

RANTES production from CD4+ lymphocytes correlates with host genotype and rates of human immunodeficiency virus type 1 disease progression

Several chemokine and chemokine receptor parameters were measured in peripheral blood mononuclear cells obtained from patients before they became infected with human immunodeficiency virus type 1 (HIV-1). After HIV-1 infection, the parameters were compared with plasma HIV-1 RNA levels and with rates of CD4(+) lymphocyte decline. Patients who were heterozygous for the Delta32CCR5 allele had significantly higher levels of RANTES production from their CD4(+) lymphocytes than did patients who did not carry the Delta32CCR5 allele (P=.01). Higher RANTES production levels from ex vivo-activated CD4(+)-enriched lymphocytes, but not CD8(+) lymphocytes, correlated with lower plasma HIV-1 RNA levels 9-12 months after infection (P= .01) and with slower rates of CD4(+) lymphocyte decline (P= .002). CCR5 expression levels on ex vivo-activated CD4(+) lymphocytes did not correlate with markers of disease progression. These results further support the hypothesis that chemokine production levels are associated with HIV-1 replication in vivo.

The power of the European Union protocol to test for carcinogenicity of inhaled fibers

We evaluate the power of a recent protocol proposed by the European Union (EU) for testing the carcinogenicity of inhaled fibers. We assume that every fiber has oncogenic potential determined by its biopersistence. We use a recently estimated potency for the oncogenic potential of fibers together with experimentally determined "weighted" half-lives (WHL) of a dozen fibers to generate simulations of long-term bioassays conducted according to the EU protocol. We analyze these experiments using standard statistical techniques and determine the number of tests that would have yielded significant results. We conclude that the EU protocol will readily detect the carcinogenic effect of long-lived fibers, such as amosite with a WHL of more than 450 days, and usually detect the effect of fibers, such as RCF1a, with WHL of about 40-50 days. However, the EU protocol has very low power to detect effects of short-lived fibers, such as X607, with WHL of about 10 days.