Three-dimensional dynamics of breakout afterburner ion acceleration using high-contrast short-pulse laser and nanoscale targets

Breakout afterburner (BOA) laser-ion acceleration has been demonstrated for the first time in the laboratory. In the BOA, an initially solid-density target undergoes relativistically induced transparency, initiating a period of enhanced ion acceleration. First-ever kinetic simulations of the BOA in three dimensions show that the ion beam forms lobes in the direction orthogonal to laser polarization and propagation. Analytic theory presented for the electron dynamics in the laser ponderomotive field explains how azimuthal symmetry breaks even for a symmetric laser intensity profile; these results are consistent with recent experiments at the Trident laser facility.

A low dielectric study on hybrid plasma-polymer thin films of different ratio between toluene and TEOS

Organic-inorganic hybrid co-polymer thin films were deposited on silicon(100) substrates under the several ratio of TEOS (tetraethoxysilane) against toluene by plasma enhanced chemical vapour deposition (PECVD) method. Toluene and TEOS were utilized as organic and inorganic precursors each, and hydrogen and argon were also used as a bubbler and carrier gases, respectively. In order to compare the difference of the electrical and the mechanical properties of the plasma polymerized thin films, we grew the hybrid co-polymer thin films under the conditions of various ratio between toluene and TEOS with fixed RF (radio frequency using 13.56 MHz) powers at 30 W. The as-grown polymerized thin films were in first analyzed by FT-IR and XPS. The result of FT-IR showed that the co-polymer thin films were polymerized with fragmented each precursor. Also, XPS results showed the chemical species and binding energies of each species. Si 2p core-level spectra from the hybrid polymer thin film showed the status of Si oxidation number. Impedance analyzer was utilized for the measurements of I-V curves and capacitance values. Also, the thin films were analyzed for hardness and Young's modulus by nano-indenter.

A novel high resolution ion wide angle spectrometer

A novel ion wide angle spectrometer (iWASP) has been developed, which is capable of measuring angularly resolved energy distributions of protons and a second ion species, such as carbon C(6 +), simultaneously. The energy resolution for protons and carbon ions is better than 10% at ∼50 MeV/nucleon and thus suitable for the study of novel laser-ion acceleration schemes aiming for ultrahigh particle energies. A wedged magnet design enables an acceptance angle of 30°(∼524 mrad) and high angular accuracy in the μrad range. First, results obtained at the LANL Trident laser facility are presented demonstrating high energy and angular resolution of this novel iWASP.

Development of a high resolution and high dispersion Thomson parabola

Here, we report on the development of a novel high resolution and high dispersion Thomson parabola for simultaneously resolving protons and low-Z ions of more than 100 MeV/nucleon necessary to explore novel laser ion acceleration schemes. High electric and magnetic fields enable energy resolutions of ΔE∕E < 5% at 100 MeV/nucleon and impede premature merging of different ion species at low energies on the detector plane. First results from laser driven ion acceleration experiments performed at the Trident Laser Facility demonstrate high resolution and superior species and charge state separation of this novel Thomson parabola for ion energies of more than 30 MeV/nucleon.

Pulse shape measurements using single shot-frequency resolved optical gating for high energy (80 J) short pulse (600 fs) laser

Relevant to laser based electron/ion accelerations, a single shot second harmonic generation frequency resolved optical gating (FROG) system has been developed to characterize laser pulses (80 J, ∼600 fs) incident on and transmitted through nanofoil targets, employing relay imaging, spatial filter, and partially coated glass substrates to reduce spatial nonuniformity and B-integral. The device can be completely aligned without using a pulsed laser source. Variations of incident pulse shape were measured from durations of 613 fs (nearly symmetric shape) to 571 fs (asymmetric shape with pre- or postpulse). The FROG measurements are consistent with independent spectral and autocorrelation measurements.

Caregiving appraisal of family caregivers for older stroke patients in Korea

PURPOSE

The purpose of this study was to investigate factors related to caregiving appraisal for family caregivers of older stroke patients in Korea.

METHOD

A descriptive, cross-sectional survey of a sample of 242 family caregivers (95.7% response rate) was conducted in Korea from 1 January 2005 to 4 January 2007. Data were collected from outpatient stroke centres at three hospitals and two home health agencies located in Seoul, the capital city of Korea, its suburban area of Kyunggi-do, and the rural areas Gyeongsangbuk-do and Chungcheongbuk-do. The questionnaire was self-administered. spss 13.0 (SPSS, Inc., Chicago, IL, USA) was used to perform frequency, percentage, mean standard deviation, t-test or analysis of variance, and Pearson's correlation calculations.

RESULTS

Caregiving appraisal was statistically different based on the caregiver's location of residency and the relationship between the caregiver and the recipient. The caregivers who resided in urban areas reported higher scores of caregiving appraisal compared with those who resided in rural areas. With regard to the caregiver-recipient relationship, spouses reported the highest caregiving distress status, followed by daughters-in-law, sons and, finally, daughters. In addition, caregiving distress significantly correlated with age (r = 0.151, P = 0.022), the number of caregiving hours per week (r = 0.198, P = 0.003) and filial obligations (r = 0.336, P = 0.000).

DISCUSSION

The study results helped to better understand the caregiving process of Korean family caregivers. The data emphasized the importance of examining the expression of cultural roles and individual values on the caregivers' quality of life in diverse cultures. The knowledge gained from this study will be utilized to develop culture-specific interventions and social policies to directly support Korean family caregivers and to indirectly support stroke patients.

The prevalence, characteristics and correlates of falls in Korean community-dwelling older adults

BACKGROUND

The risk factors for falls that have been reported in Caucasian older adults may not be the same for Korean older adults.

OBJECTIVE

To examine the prevalence, characteristics and correlates of falls among community-dwelling older adults in Korea.

METHODS

A stratified random sampling method was conducted to recruit participants, and 335 were eligible to participate from September 2006 to March 2007. Socio-demographic data, history of disease and medications, activities of daily living (ADL), cognitive status, health behaviour and fall incidents were collected. Descriptive statistics were used to describe the sample. The prevalence of falls was obtained. Univariate analyses for risk factors of falls using chi-square and t-test statistics, and multivariate logistic regression analyses for correlates of falls were performed.

RESULTS

Of the 335 older adults, 48 (15%) elderly had experienced falls. There was a significant difference between older adults who fell and those who did not fall with regard to ADL and exercise behaviour. Non-fallers had higher ADL scores and showed higher levels of adherence to exercise than fallers. The independent risk factor for falls was ADL.

CONCLUSIONS/IMPLICATIONS

In this study, an individual's functional status and exercise engagement were significant factors that differentiated fallers and non-fallers. Therefore, an effective fall prevention programme should be focused on encouraging older adults to participate in regular exercise.

Radiation-pressure acceleration of ion beams driven by circularly polarized laser pulses

We present experimental studies on ion acceleration from ultrathin diamondlike carbon foils irradiated by ultrahigh contrast laser pulses of energy 0.7 J focused to peak intensities of 5x10(19) W/cm2. A reduction in electron heating is observed when the laser polarization is changed from linear to circular, leading to a pronounced peak in the fully ionized carbon spectrum at the optimum foil thickness of 5.3 nm. Two-dimensional particle-in-cell simulations reveal that those C6+ ions are for the first time dominantly accelerated in a phase-stable way by the laser radiation pressure.

Enhanced laser-driven ion acceleration in the relativistic transparency regime

We report on the acceleration of ion beams from ultrathin diamondlike carbon foils of thickness 50, 30, and 10 nm irradiated by ultrahigh contrast laser pulses at intensities of approximately 7 x 10;{19} W/cm;{2}. An unprecedented maximum energy of 185 MeV (15 MeV/u) for fully ionized carbon atoms is observed at the optimum thickness of 30 nm. The enhanced acceleration is attributed to self-induced transparency, leading to strong volumetric heating of the classically overdense electron population in the bulk of the target. Our experimental results are supported by both particle-in-cell (PIC) simulations and an analytical model.

c-Src tyrosine kinase co-associates with and phosphorylates signal transducer and activator of transcription 5b which mediates the proliferation of normal human B lymphocytes

c-Src is the normal human cellular protein homologue of the viral oncogene v-src. c-Src activity was reported recently to increase in CD40-activated human B lymphocytes, suggesting its involvement in proliferation. To elucidate the exact role of c-Src in this process, we investigated the effects of c-Src over-expression on normal B lymphocyte growth. B lymphocytes purified from human peripheral blood were infected with Ad5/F35 vector encoding either a constitutively active c-Src (c-Src/dominant-positive) or a dominant-negative c-Src (c-Src/DN). Little variation of B lymphocytes expansion could be observed between control enhanced yellow fluorescent protein and c-Src/dominant-positive-infected cells. In contrast, over-expression of c-Src/DN results in a 40% inhibition of B lymphocyte expansion. These results suggest that DN c-Src may compete with endogenous c-Src, resulting in partial inhibition of a transcriptional pathway involved in B lymphocyte proliferation. We demonstrate further that c-Src can phosphorylate signal transducer and activator of transcription 5b (STAT5b) on tyrosine 699 and that c-Src and STAT5b co-associate during B lymphocyte proliferation. These results confirm an important role for c-Src in the expansion of normal human B lymphocytes in vitro, in which c-Src may regulate STAT5b in the intracellular signalling pathway important for the proliferation of normal human B lymphocytes.

Effects of an acute exposure to toluene on the DNA repair activity of the human 8-oxoguanine DNA glycosylase 1 (hOGG1) in healthy subjects

The structure and previous studies on the biotransformation of toluene lead to the suspicion that metabolites may be formed which preferentially react with strongly nucleophilic partners such as sulfhydryl groups of cysteines in proteins. Human 8-oxoguanine DNA glycosylase 1 removes the major oxidative DNA damage and possesses eight cysteines. Its potential inactivation may lead to accumulation of DNA damage by reactive oxygen species formed by exogenous agents or by ubiquitous endogenous processes. The goal of the present investigation was to study the in vivo effect in humans of an acute toluene exposure on hOGG1 activity. Twenty healthy, non-smoking males were exposed to 50 ppm toluene and to filtered air in an exposure chamber for 270 min, using a cross-over design. Before and 30 min after the end of exposure, blood samples were taken and toluene concentrations and the hOGG1 activity were measured. hOGG1 activity was determined in peripheral mononuclear blood cells. Thirty minutes after exposure to toluene, we found a median blood concentration of 0.25 mg toluene/l. Compared with the activity before exposure, upon exposure to toluene a statistically insignificant median increase of hOGG1 activity by +0.4% and upon exposure to air by +2.3% was determined. Thus, no reduction of the hOGG1 repair activity after acute exposure to 50 ppm toluene was observed.

Hypolipidemic effects of silymarin are not mediated by the peroxisome proliferator-activated receptor alpha

Silymarin is widely used in supportive therapy of liver diseases. It has been shown lately that silymarin has beneficial effects on some risk factors of atherosclerosis owing to its hypolipidemic properties. PPARalpha plays a key role in lipid metabolism and homeostasis as its target genes are involved in catabolism of fatty acids by beta-oxidation (e.g. acyl-CoA oxidase) and by omega-oxidation (e.g. cytochrome P4504A). Here we studied the possibility that hypolipidemic effects of silymarin may be mediated by PPARalpha. Rats fed with a high-cholesterol diet with either silymarin or fenofibrate (as a positive control both for PPARalpha expression as well as for lipid determination) were used. The effects of silymarin on expression of PPARalpha both at the mRNA (including selected target genes) as well as the protein level were determined. In parallel, the levels of cholesterol and triacylglycerols were determined. Our results confirmed the hypolipidemic effects of silymarin and demonstrated that these effects are probably not mediated by PPARalpha because of unchanged mRNA levels of PPARalpha target genes. Furthermore, this work shows for the first time that cholesterol itself inhibits expression of CYP4A mRNA.

No acute effects of an exposure to 50 ppm acetaldehyde on the upper airways

OBJECTIVE

German MAK value of acetaldehyde has been fixed at 50 ppm to prevent from irritating effects. The threshold value is mainly based on animal experiments. The aim of this study was to evaluate acute effects of an exposure to 50 ppm acetaldehyde on the upper airways of human subjects.

METHODS

Twenty subjects were exposed to 50 ppm acetaldehyde and to air in an exposure chamber for 4 h according to a crossover design. Subjective symptoms were assessed by questionnaire. Olfactory threshold for n-butanol and mucociliary transport time were measured before and after exposure. Concentrations of interleukin 1beta and interleukin 8 were determined in nasal secretions taken after exposure. mRNA levels of interleukins 1beta, 6 and 8, tumour necrosis factor alpha, granulocyte-macrophage colony-stimulating factor, monocyte chemotactic protein 1, and cyclooxygenases 1 and 2 were measured in nasal epithelial cells, gained after exposure. Possible effects were investigated by semiparametric and parametric crossover analyses.

RESULTS

Exposure to acetaldehyde did not cause any subjective irritating symptoms. Olfactory threshold did not change. Mucociliary transport time increased insignificantly after exposure to acetaldehyde. Neither concentrations of interleukins in nasal secretions nor mRNA levels of inflammatory factors were higher after exposure to acetaldehyde.

CONCLUSION

An acute exposure to 50 ppm acetaldehyde did not cause any adverse effects in test subjects.

Experimental characterization of picosecond laser interaction with solid targets

We have characterized the plasma produced by a picosecond laser pulse using x-ray spectroscopy. High-resolution high-sensitivity spectra of K -shell emission from a Ti plasma have been obtained, showing a strong contribution from multiply ionized ions. Hydrodynamic and collisional-radiative codes are used to extract the plasma temperature and density from these measurements. We show that our measurements can provide benchmarks for particle-in-cell (PIC) simulations of preplasma conditions in ultraintense laser-matter interactions.

Wide angle crystal spectrometer for angularly and spectrally resolved X-ray scattering experiments

A novel wide angle spectrometer has been implemented with a highly oriented pyrolytic graphite crystal coupled to an image plate. This spectrometer has allowed us to look at the energy resolved spectrum of scattered x rays from a dense plasma over a wide range of angles (approximately 30 degrees ) in a single shot. Using this spectrometer we were able to observe the temporal evolution of the angular scatter cross section from a laser shocked foil. A spectrometer of this type may also be useful in investigations of x-ray line transfer from laser-plasmas experiments.

Discovery of TH-302: An achiral hypoxia-activated cytotoxic prodrug

3515

Background: Selective targeting of the hypoxic compartment of the tumor microenvironment is both a challenge and an opportunity for discovering and developing new cancer therapeutics. Chronic and transient hypoxia underlie resistance to chemotherapeutics and radiation. We have taken a modular design approach to synthesize hypoxia-activated prodrugs. Different nitro-containing heterocyclic triggers were linked to bis alkylating phosphorous mustard toxins and profiled in in vitro and in vivo assays predictive of compound efficacy and pharmacokinetics (PK). Methods: Drug candidates were synthesized and characterized using standard synthetic methods. In vitro efficacy was assessed with cancer cell line cytotoxicity and clonogenic assays. In vivo efficacy was assessed with xenograft models in monotherapy and combination therapy modes. Results: Screening trigger-toxin combinations in H460 lung cancer cell proliferation assays under anoxic, hypoxic, and aerobic conditions yielded structure-activity relationships (SAR) and identified TH- 302, a 2-nitroimidazole triggered bromo analog of ifosfamide, as a potent and selective molecule. TH-302 exhibits in vitro proliferation IC50 values of 0.2, 5, and 90μM and clonogenic IC90 values of 0.1, 5, and 30μM under conditions of 0%, 0.6%, and 21% O2, respectively. In vitro profiling showed sufficient solubility, plasma and microsomal stability, resistance to drug efflux mechanisms, and PK. In vivo efficacy was assessed with the H460 ectopic xenograft model. TH-302 administered alone (100mpk, ip, Q3Dx5) or in combination with cisplatin (6mpk, iv, Q7Dx2) showed mean tumor volume growth delays to 500mm3 (TGD500) of 10 days for TH-302 alone, 4 days for cisplatin alone, and 20 days for the combination. These results have been confirmed and extended using different tumor models, dosing regimens, and combinations which included Taxol and 5-FU. TH-302 demonstrates dose-proportional PK in multiple species. Conclusions: TH-302, a novel hypoxia-activated cytotoxic prodrug, has promising preclinical in vitro and in vivo efficacy and selectivity and has entered IND-enabling studies. Acute and subchronic toxicology is underway in rats and dogs. We expect to file an IND for clinical studies of TH-302 this year.

No significant financial relationships to disclose.

Size Matters More Than Chemistry for Cloud-Nucleating Ability of Aerosol Particles

Size-resolved cloud condensation nuclei (CCN) spectra measured for various aerosol types at a non-urban site in Germany showed that CCN concentrations are mainly determined by the aerosol number size distribution. Distinct variations of CCN activation with particle chemical composition were observed but played a secondary role. When the temporal variation of chemical effects on CCN activation is neglected, variation in the size distribution alone explains 84 to 96% of the variation in CCN concentrations. Understanding that particles' ability to act as CCN is largely controlled by aerosol size rather than composition greatly facilitates the treatment of aerosol effects on cloud physics in regional and global models.

A systematic review of risk factors associated with near-fatal and fatal asthma

BACKGROUND

Asthma mortality and morbidity continue to be a serious global problem. Systematic reviews provide an opportunity to review risk factors in detail.

OBJECTIVE

To review all of the literature for risk factors associated with near-fatal asthma (NFA) and fatal asthma (FA).

METHODS

A literature search from 1960 to January 2004 in MEDLINE and EMBASE was conducted. Studies were included based on the following criteria: NFA was defined as an asthma exacerbation resulting in respiratory arrest requiring mechanical ventilation or a partial pressure of CO2 of at least 45 mmHg or asthma resulting in death (FA); the study reported the number of cases (NFA and/or FA) and asthmatic controls; there was explicit reporting of risk factors; cases that were adult and pediatric in nature; and all study types. Studies that included patients with chronic obstructive pulmonary disease were excluded.

RESULTS

Four hundred and three articles were identified, of which 27 met the inclusion criteria. Increased use of medications such as beta-agonists via metered dose inhalers (OR=1.67, 95% CI 0.99 to 2.84, P=0.057) and nebulizers (OR=2.45, 95% CI 1.52 to 3.93, P=0.0002), oral steroids (OR=2.71, 95% CI 1.34 to 5.51, P=0.006) and oral theophylline (OR=2.02, 95% CI 1.03 to 3.98, P=0.04) and a history of hospital (OR=2.62, 95% CI 1.04 to 6.58, P=0.04) and/or intensive care unit (OR=5.14, 95% CI 1.91 to 13.86, P=0.001) admissions and mechanical ventilation (OR=6.69, 95% CI 2.80 to 15.97, P=0.0001) due to asthma were predictors of NFA and FA. Prior emergency department assessment did not confer a greater risk of NFA and FA (OR=1.13, 95% CI 0.43 to 2.92, P=0.810). The use of inhaled corticosteroids (ICS) measured in a dose-independent fashion (did the patient take ICS previously; yes or no) inferred equivocal risk of NFA and FA (OR=1.31, 95% CI 0.83 to 2.05, P=0.25). However, two studies measured the use of ICS in a dose-dependent fashion (ie, measured the number of prescriptions filled within the previous six to 12 months). Both studies showed a trend toward a protective effect against FA. One study showed that the premature cessation of ICS can hasten death.

CONCLUSIONS

In the present study, risk factors of NFA and FA have been more accurately defined. Clinicians should identify patients with these characteristics to reduce their risk of NFA and FA. Further research should focus on quantifying the impact of risk factors on asthma deaths.

Traveling wave fronts and localized traveling wave convection in binary fluid mixtures

Nonlinear fronts between spatially extended traveling wave (TW) convection and quiescent fluid and spatially localized traveling waves (LTWs) are investigated in quantitative detail in the bistable regime of binary fluid mixtures heated from below. A finite-difference method is used to solve the full hydrodynamic field equations in a vertical cross section of the layer perpendicular to the convection roll axes. Results are presented for ethanol-water parameters with several strongly negative separation ratios where TW solutions bifurcate subcritically. Fronts and LTWs are compared with each other and similarities and differences are elucidated. Phase propagation out of the quiescent fluid into the convective structure entails a unique selection of the latter while fronts and interfaces where the phase moves into the quiescent state behave differently. Interpretations of various experimental observations are suggested.

[Phytobezoars: case report and review of the literature]

We report on the case of a 40-year-old woman with a long year history of vegetarian lifestyle, who experienced a phytobezoar induced acute abdomen due to a mechanic small bowel ileus. After uncomplicated surgical treatment and post-OP course the patient could be discharged on post-OP day 10. Beside a description of the historical background, relevant diagnostic and therapeutic aspects are mentioned as well as a review of the relevant literature.

Oscillatory convection in binary mixtures: thermodiffusion, solutal buoyancy, and advection

The role of thermodiffusive generation of concentration fluctuations via the Soret effect, their contribution to the buoyancy forces that drive convection, the advective mixing effect of the latter, and the diffusive homogenisation are compared and elucidated for oscillatory convection. Numerically obtained solutions of the field equations in the form of spatially extended relaxed traveling waves, of standing waves, and of the transient growth of standing waves and their transition to traveling waves are discussed as well as spatially localized convective states of traveling waves that are surrounded by the quiescent fluid.

Standing-wave oscillations in binary mixture convection: from the onset via symmetry breaking to period doubling into chaos

Oscillatory solution branches of the hydrodynamic field equations describing convection in the form of a standing wave (SW) in binary fluid mixtures heated from below are determined completely for several negative Soret coefficients psi. Galerkin as well as finite-difference simulations were used. They were augmented by simple control methods to obtain also unstable SW states. For sufficiently negative psi, unstable SWs bifurcate subcritically out of the quiescent conductive state. They become stable via a saddle-node bifurcation when lateral phase pinning is exerted. Eventually their invariance under timeshift by half a period combined with reflection at midheight of the fluid layer gets broken. Thereafter, they terminate by undergoing a period-doubling cascade into chaos.

Human ileal bile acid transporter gene ASBT (SLC10A2) is transactivated by the glucocorticoid receptor

BACKGROUND

Patients with Crohn's disease suffer from intestinal bile acid malabsorption. Intestinal bile acid absorption is mediated by the apical sodium dependent bile acid transporter ASBT/IBAT (SLC10A2). In rats, ASBT is induced by glucocorticoids.

AIMS

To study whether human ASBT is activated by glucocorticoids and to elucidate the mechanism of regulation.

PATIENTS AND METHODS

ASBT expression in ileal biopsies from patients with Crohn's disease and from healthy subjects was quantified by western blot. ASBT promoter function was studied in luciferase assays and by electrophoretic mobility shift assay.

RESULTS

In 16 patients with Crohn's disease, ASBT expression was reduced to 69 (7.5)% compared with healthy controls (mean (SEM); p = 0.01). In 10 healthy male volunteers, ASBT protein expression was increased 1.34 (0.11)-fold (mean (SEM); p<0.05) after 21 days' intake of budesonide (9 mg/day) whereas expression of the peptide transporter 1 was unaffected. Reporter constructs of the human ASBT promoter were activated 15-20-fold by coexpression of the glucocorticoid receptor (GR) and exposure to the GR ligands dexamethasone or budesonide. Two glucocorticoid response elements in the ASBT promoter, arranged as inverted hexanucleotide repeats (IR3 elements), conferred inducibility by GR and dexamethasone in a heterologous promoter context and were shown to bind GR in mobility shift assays.

CONCLUSIONS

Human ASBT is induced by glucocorticoids in vitro and in vivo. Induction of ASBT by glucocorticoids could be beneficial in patients with Crohn's disease who exhibit reduced ASBT expression. This study identifies ASBT as a novel target of glucocorticoid controlled gene regulation in the human intestine.

Interpretation of the magnetic structures of Cu2Te2O5X2 (X = Cl, Br) and Ca3.1Cu0.9RuO6 on the basis of electronic structure considerations: cases for strong super-superexchange interactions involving Cu2+ ions

For super-superexchange interactions between Cu(2+) ions, a qualitative rule was formulated to assess their strengths based on the geometrical parameters of the exchange paths. Spin dimer analysis was carried out for Cu(2)Te(2)O(5)X(2) (X = Cl, Br) and Ca(3.1)Cu(0.9)RuO(6) to evaluate the relative strengths of their superexchange and super-superexchange interactions. The strongest antiferromagnetic interactions in Cu(2)Te(2)O(5)X(2) (X = Cl, Br) are given by the super-superexchange interactions involving the most linear Cu-X.X-Cu paths between tetrahedral clusters Cu(4)O(8)X(4) along the (a +/- b)-directions. The adjacent CuRuO(6) chains of Ca(3.1)Cu(0.9)RuO(6) are antiferromagnetically coupled through the most linear Cu-O.O-Cu paths along the direction perpendicular to the plane of the CuRu zigzag chain. The spin lattices of Cu(2)Te(2)O(5)X(2) and Ca(3.1)Cu(0.9)RuO(6) deduced from our spin dimer analysis are consistent with the available magnetic data. The spin lattice of a magnetic solid should be determined on the basis of appropriate electronic structure considerations.

Cranial nerve function in workers exposed to polychlorinated dioxins and furans

OBJECTIVE

To look for possible effects of polychlorinated dioxins and furans (PCDD/F) on cranial nerve function.

MATERIAL AND METHODS

Clinical and neurophysiological examinations [visual and brainstem auditory evoked potentials (VEP and BAEP), blink reflex] in 121 PCDD/F exposed workers of one pesticide producing plant.

RESULTS

BAEP abnormalities were more frequent in workers with chloracne (6 of 33 workers, 18.2%) than in those without chloracne (7 of 84, 8.3%), but this was not statistically significant (chi2: 2.33). VEP abnormalities were seen in one worker with and two without chloracne. Clinically visual functions were normal except in one worker, who was amaurotic since birth. Blink reflex abnormalities without corresponding clinical findings were observed in two patients without chloracne.

CONCLUSION

Severe exposure to PCDD/F is not followed by clinical signs of cranial nerve dysfunction but may create an increased risk for abnormal BAEP findings, which were more than twice as common in workers with chloracne. Although this difference did not reach statistical significance, it cannot exclude a toxic effect of PCDD/F, as statistical significance is difficult to achieve with such small numbers of workers. In none of the workers, BAEP abnormalities were accompanied by clinical signs of hearing dysfunction.

Localized waves without the existence of extended waves: oscillatory convection of binary mixtures with strong soret effect

Spatially confined solutions of traveling convection rolls are determined numerically for binary mixtures such as ethanol-water. The appropriate field equations are solved in a vertical cross section of the rolls perpendicular to their axes subject to realistic horizontal boundary conditions. The localized convective states are stably and robustly sustained by strongly nonlinear mixing and complex flow-induced concentration redistribution. We elucidate how this enables their existence for strongly negative separation ratios at small subcritical heating rates below the saddle node of extended traveling convection rolls where the quiescent fluid is strongly stable.

Effects of an external exposure to 200 ppm methyl ethyl ketone on nasal mucosa in healthy volunteers

OBJECTIVES

To investigate the effects of an acute exposure to 200 ppm methyl ethyl ketone on the nasal mucosa of healthy volunteers.

METHODS

Nineteen healthy non-smoking men were exposed to 200 ppm methyl ethyl ketone and to a sham exposure in an exposure chamber, using a cross-over design. Mucociliary transport time was determined with the saccharine test. Interleukin (IL)-1beta, IL-6, IL-8, and tumor necrosis factor-alpha (TNFalpha) were measured in nasal secretions. Subjective symptoms were assessed by questionnaire.

RESULTS

Mucociliary transport time was significantly higher (660 vs. 600 s (medians), P = 0.01) after solvent exposure. Concentrations of IL-1beta and IL-8 were insignificantly elevated after exposure (IL-1beta: 83.8 pg/ml vs. 48.1 pg/ml, medians, P = 0.11; IL-8: 14471 pg/ml vs. 11080 pg/ml, P = 0.12), whereas those of IL-6 and TNFalpha remained unchanged. Subjects did not feel any irritation of nasal mucosa.

CONCLUSION

Concentrations of organic solvents not exceeding their MAK values can cause subclinical rhinitis. The secretion of proinflammatory cytokines and impairment of mucociliary transport can explain the development of clinical rhinitis in highly exposed subjects.

Characterization of the human OATP-C (SLC21A6) gene promoter and regulation of liver-specific OATP genes by hepatocyte nuclear factor 1 alpha

OATP-C (SLC21A6) is the predominant Na(+)-independent uptake system for bile salts and bilirubin of human liver and is expressed exclusively at the basolateral (sinusoidal) hepatocyte membrane. To investigate the basis of liver-specific expression of OATP-C, we studied promoter function in the two hepatocyte-derived cell lines HepG2 and Huh7 and in nonhepatic HeLa cells. OATP-C promoter constructs containing from 66 to 950 nucleotides of 5'-regulatory sequence were active in HepG2 and Huh7 but not HeLa cells, indicating that determinants of hepatocyte-specific expression reside within the minimal promoter. Deoxyribonuclease I footprint analysis revealed a single region that was protected by HepG2 and Huh7 but not HeLa cell nuclear extracts. The liver-enriched transcription factor hepatocyte nuclear factor 1 alpha (HNF1 alpha) was shown by mobility shift assays to bind within this footprint. Coexpression of HNF1 alpha stimulated OATP-C promoter activity 30-fold in HepG2 and 49-fold in HeLa cells. Mutation of the HNF1 site abolished promoter function, indicating that HNF1 alpha is critical for hepatocyte-specific OATP-C gene expression. The human OATP8 (SLC21A8) and mouse Oatp4 (Slc21a6) promoters were also responsive to HNF1 alpha coexpression in HepG2 cells. These data support a role for HNF1 alpha as a global regulator of liver-specific bile salt and organic anion transporter genes.

Influence of inlet and bulk noise on Rayleigh-Bénard convection with lateral flow

Spatiotemporal properties of convective fluctuations and of their correlations are investigated theoretically in the vicinity of the threshold for onset of convection in the presence of a lateral through-flow using the full linearized equations of fluctuating hydrodynamics. The effect of external forcing by inlet boundary conditions on the downstream evolution of convective fields is separated from the effect of internal bulk thermal forcing with the use of spatial Laplace transformations. They show how the spatial variation of fluctuations and of their correlations are governed by the six spatial characteristic exponents of the field equations.

No effects of pulsed radio frequency electromagnetic fields on melatonin, cortisol, and selected markers of the immune system in man

There is growing public concern that radio frequency electromagnetic fields may have adverse biological effects. In the present study eight healthy male students were tested to see whether or not radio frequency electromagnetic fields as used in modern digital wireless telecommunication (GSM standard) have noticeable effects on salivary melatonin, cortisol, neopterin, and immunoglobulin A (sIgA) levels during and several hours after exposure. In a specifically designed, shielded experimental chamber, the circularly polarized electromagnetic field applied was transmitted by an antenna positioned 10 cm behind the head of upright sitting test persons. The carrier frequency of 900 MHz was pulsed with 217 Hz (average power flux density 1 W/m2). In double blind trials, each test person underwent a total of 20 randomly allotted 4 hour periods of exposure and sham exposure, equally distributed at day and night. The results obtained show that the salivary concentrations of melatonin, cortisol, neopterin and sIgA did not differ significantly between exposure and sham exposure.

Telomere-independent reduction of human B lymphocyte: proliferation during long-term culture

Telomeres and telomerase, the telomere lengthening enzyme, have been shown to play a central role in the long-term ability of cells to proliferate and maintain viability. In opposition to transformed cells, normal somatic cells express a low level of telomerase, which results in the gradual shortening of their telomeres after each division and in cell senescence once a critical telomere length is reached. We have tested the hypothesis that shortening of telomeres could limit the expansion of normal human B lymphocytes maintained in long-term culture using a CD40/CD154 system. Measurement of temolerase activity in cell lysates showed a rapid up-regulation of telomerase following the initiation of the culture that was dependent on the CD40 signaling. The high level of telomerase activity and the corresponding long telomere structures remained constant for the 35 day culture period in which a gradual reduction of the cell expansion rate is observed. We conclude that the gradual in vitro senescence of cultured B cells does not correlate with a corresponding loss of telomerase activity and of telomere length. Rather the phenomenon may be related to an intrinsic property of the proliferating B cells to differentiate into Ig-secreting cells.

Human Ku70 interacts with heterochromatin protein 1alpha

Ku is involved in the metabolism of DNA ends, DNA repair, and the maintenance of telomeres. It consists of a heterodimer of 70- and 80-kDa subunits. Recently we have demonstrated that Ku70 interacted with TRF2, a mammalian telomere-binding protein. Using the same yeast two-hybrid screening system, we now show that Ku70 also interacts with heterochromatin protein 1alpha (HP1alpha), a protein known to be associated with telomeres as well as heterochromatin. HP1 is a suppressor of the position effect variegation in Drosophila and acts as a transcriptional suppressor in mammalian cells. The interaction with Ku70 in the two-hybrid system was confirmed by a glutathione S-transferase pull-down study using bacterial recombinant proteins in vitro. The interaction was also reproduced in vivo in HeLa cells, where endogenous Ku70 coimmunoprecipitated with HP1alpha. This interaction was more effective in acidic pH and weakened considerably as the pH of the reaction buffer was elevated up to 7.5. Ku80 did not interact with HP1alpha directly. The interaction domains of Ku70 and HP1alpha included the Leu-Ser repeat (amino acids 200-385) and the chromo shadow domain, respectively. Ku70 was largely colocalized with transfected HP1alpha but not with a C-terminal deletion mutant, HP1alpha(Delta)C. In contrast to HP1alpha, Ku70 did not repress transcriptional activity of the reporter gene when tethered to DNA after transfection to mammalian cells. The implication of this interaction is discussed.