Nanoscale imaging of InN segregation and polymorphism in single vertically aligned InGaN/GaN multi quantum well nanorods by tip-enhanced Raman scattering.

Vertically aligned GaN nanorod arrays with nonpolar InGaN/GaN multi quantum wells (MQW) were grown by MOVPE on c-plane GaN-on-sapphire templates. The chemical and structural properties of single nanorods are optically investigated with a spatial resolution beyond the diffraction limit using tip-enhanced Raman spectroscopy (TERS). This enables the local mapping of variations in the chemical composition, charge distribution, and strain in the MQW region of the nanorods. Nanoscale fluctuations of the In content in the InGaN layer of a few percent can be identified and visualized with a lateral resolution below 35 nm. We obtain evidence for the presence of indium clustering and the formation of cubic inclusions in the wurtzite matrix near the QW layers. These results are directly confirmed by high-resolution TEM images, revealing the presence of stacking faults and different polymorphs close to the surface near the MQW region. The combination of TERS and HRTEM demonstrates the potential of this nanoscale near-field imaging technique, establishing TERS as a very potent, comprehensive, and nondestructive tool for the characterization and optimization of technologically relevant semiconductor nanostructures.

A HIF-1α-driven feed-forward loop augments HIF signalling in Hep3B cells by upregulation of ARNT.

Oxygen-deprived (hypoxic) areas are commonly found within neoplasms caused by excessive cell proliferation. The transcription factor Aryl hydrocarbon receptor nuclear translocator (ARNT) is part of the hypoxia-inducible factor (HIF) pathway, which mediates adaptive responses to ensure cellular survival under hypoxic conditions. HIF signalling leads to metabolic alterations, invasion/metastasis and the induction of angiogenesis in addition to radio-chemoresistance of tumour cells. Activation of the HIF pathway is based on the abundance of HIF-α subunits, which are regulated in an oxygen-dependent manner and form transcriptional active complexes with ARNT or ARNT2 (also referred as HIF-1ß and HIF-2ß, respectively). ARNT is considered to be unaffected by hypoxia but certain cell lines, including Hep3B cells, are capable to elevate this transcription factor in response to oxygen deprivation, which implies an advantage. Therefore, the aim of this study was to elucidate the mechanism of hypoxia-dependent ARNT upregulation and to determine implications on HIF signalling. Gene silencing and overexpression techniques were used to alter the expression pattern of HIF transcription factors under normoxic and hypoxic conditions. qRT-PCR and western blotting were performed to measure gene and protein expression, respectively. HIF activity was determined by reporter gene assays. The results revealed a HIF-1α-dependent mechanism leading to ARNT upregulation in hypoxia. Forced expression of ARNT increased reporter activity under normoxic and hypoxic conditions. In conclusion, these findings indicate a novel feed-forward loop and suggest that ARNT might be a limiting factor. Augmented HIF signalling in terms of elevated target gene expression might be advantageous for tumour cells.

EEG-tomographic studies with LORETA on vigilance differences between narcolepsy patients and controls and subsequent double-blind, placebo-controlled studies with modafinil.

The aim of the present study was to identify brain regions associated with vigilance in untreated and modafinil-treated narcoleptic patients by means of low-resolution brain electromagnetic tomography (LORETA). 16 drug-free narcoleptics and 16 normal controls were included in the baseline investigation. Subsequently patients participated in a double-blind, placebo-controlled crossover study receiving a three-week fixed titration of modafinil (200, 300, 400 mg) and placebo. Measurements comprised LORETA, the Multiple Sleep Latency Test (MSLT) and the Epworth Sleepiness Scale (ESS) obtained before and after three weeks' therapy. Statistical overall analysis by means of the omnibus significance test demonstrated significant inter-group differences in the resting (R-EEG), but not in the vigilance-controlled recordings (V-EEG). Subsequent univariate analysis revealed a decrease in alpha-2 and beta 1-3 power in prefrontal, temporal and parietal cortices, with the right hemisphere slightly more involved in this vigilance decrement. Modafinil 400 mg/d as compared with placebo induced changes opposite to the aforementioned baseline differences (key-lock principle) with a preponderance in the left hemisphere. This increase in vigilance resulted in an improvement in the MSLT and the ESS. LORETA provided evidence of a functional deterioration of the fronto-temporo-parietal network of the right-hemispheric vigilance system in narcolepsy and a therapeutic effect of modafinil on the left hemisphere, which is less affected by the disease.

Determination of rhodanese enzyme activity by capillary zone electrophoresis.

A new sensitive method has been developed for the determination of rhodanese activity. The enzymatic reactions were carried out directly in thermostatted autosampler vials and the formation of SCN- was monitored by sequential capillary zone electrophoretic runs. The determinations were performed in a 75-micron fused-silica capillary using 0.1 M beta-alanine-HCl (pH 3.50) as a background electrolyte, a separation voltage of 18 kV (negative polarity), a capillary temperature of 25 degrees C and direct detection at 200 nm. Short-end injection or long-end injection procedures were used for sample application. The method is rapid, able to be automated and requires only small amounts of sample and substrates, which is especially important in the case of highly toxic cyanide. The developed capillary electrophoretic method also has great potential for thiocyanate determinations in other applications.

Fibroblast inhibition: a new and treatable cause of prosthetic graft failure.

We have encountered two patients who had repeated false aneurysms, seromas, and unseated grafts which presented about 18 months after aortobifemoral grafting. An inhibitor of fibroblast growth was detected in each patient's serum by in vitro dilution tests. Normal ingrowth of fibrous tissue resumed after plasmapheresis, leaving the patients clinically stable for up to 3 1/2 years after treatment. Criteria for the diagnosis of fibroblast inhibition are an unseated prosthesis which simulates infection, no bacterial growth on carefully studied cultures, and inhibition of fibroblast growth by the patient's serum in vitro. The diagnosis should be entertained in the differential diagnosis of graft infection when an unseated graft is encountered in association with a late seroma or false aneurysm. Plasmapheresis removed the inhibitor. Fibroblast inhibition has not been reported previously.

Sleep laboratory studies in periodic limb movement disorder (PLMD) patients as compared with normals and acute effects of ropinirole.

Periodic limb movement disorder (PLMD) occurs in a variety of sleep disorders and can cause insomnia as well as hypersomnia with daytime somnolence. The aim of this study was to investigate 12 untreated PLMD patients as compared with 12 normal controls and to measure the acute effects of 0.5 mg ropinirole (Requip((R))) - a non-ergoline dopamine agonist - as compared with placebo. In three nights (adaptation, placebo, ropinirole night) objective and subjective sleep and awakening quality were evaluated. In the target variable 'periodic leg movements per hour of sleep' (PLM/(hTST)) PLMD patients showed an increased value of 42/h (normal 0-5/h) with a greater number of arousals due to periodic leg movements (PLM) in sleep. They further demonstrated an increased number of awakenings, sleep stage S1, S4, stage shifts and decreased S2, but there were no significant differences concerning total sleep time, sleep efficiency (SE), subjective sleep quality and morning measures of mood, drive and drowsiness. However, measures of attention variability, numerical memory, fine motor activity and reaction time performance were impaired. Ropinirole 0.5 mg was shown to significantly improve the index PLM/(hTST) by 64% and arousals due to PLM, increase spontaneous arousals, REM-latency, stage 2 and stage shifts and decrease SREM. In the morning attention variability was attenuated and numerical memory augmented. Thus, ropinirole improved some sleep architecture and early morning measures of performance but specifically all PLM variables, which suggests a dopaminergic pathogenesis in PLMD. Copyright 2001 John Wiley & Sons, Ltd.

Theophylline in snoring and sleep-related breathing disorders: sleep laboratory investigations on subjective and objective sleep and awakening quality.

The aim of the present investigation was to comparatively examine the effect of theophylline on various sleep-related breathing disorders of different severity. In a single-blind, placebo-controlled crossover study, 30 patients were polysomnographically diagnosed as suffering from primary snoring (n = 7), obstructive snoring (n = 12) or moderate sleep apnea (n = 11). Subsequent polysomnographic investigations included one baseline, one placebo and one theophylline (Respicur retard 400 mg, Byk Gulden, Konstanz, Germany) night. Subjective sleep and awakening quality was evaluated by means of a test battery completed in the morning. Concerning respiratory variables, theophylline was most effective in patients with moderate sleep apnea. Obstructive snorers only showed a tendency towards improvement and primary snorers remained unchanged. Sleep architecture generally remained unchanged in all three patient groups. Objective awakening quality was partly improved in primary snorers, obstructive snorers, as well as in moderate sleep apnea patients as compared with baseline, but not as compared with placebo. Regarding subjective sleep and awakening quality, only primary snorers and obstructive snorers showed an improvement, as compared with baseline while moderate sleep apnea patients remained unchanged. Based on intergroup comparison, we conclude that patients with moderate sleep apnea showed the most pronounced improvement in regard to respiratory events. Concerning sleep initiation and maintenance, sleep architecture and subjective sleep and awakening quality, no significant intergroup differences were found. Regarding objective awakening quality, attention showed a significantly greater improvement in primary than in obstructive snorers and sleep apnea patients, while motor performance was most improved in obstructive snorers.

[Daytime tiredness correlated with nocturnal respiratory and arousal variables in patients with sleep apnea: polysomnographic and EEG mapping studies]. / Tagesmüdigkeit korreliert mit nächtlichen Atmungs- und Arousal-Variablen bei Schlafapnoepatienten: Polysomnographische und EEG-Mapping-Untersuchungen.

There is evidence that daytime tiredness is caused by apnea/hypopnea with oxygen desaturation and/or by sleep fragmentation due to arousals. The aim of this study was to investigate objective and subjective sleep and awakening quality and daytime vigilance--objectified by midmorning mapping of vigilance-controlled EEG (V-EEG)--in sleep apnea patients (N: 18), as compared with age- and sex-matched normal controls (N: 18) as well as to correlate nocturnal respiratory distress and arousals to daytime brain function. Statistical analyses demonstrated a deterioration in subjective and objective sleep and awakening quality in apnea patients. Midmorning V-EEG mapping in apnea patients exhibited less total power, more delta and theta, less alpha and beta activity, as well as a slower dominant frequency and centroid of the total activity compared to controls, which suggests a vigilance decrement. The Spearman rank correlation between 6 polysomnographically registered respiratory variables and 36 diurnal quantitative EEG measures demonstrated the following: the higher the apnea, apnea-hypopnea, snoring and desaturation indices and the lower the minimum and average low oxygen saturation, the more pronounced was diurnal tiredness. Eleven arousal measures based on ASDA criteria showed the following significant correlations: the higher the nocturnal arousal index and the more arousals due to hypopneas, the greater was daytime tiredness. On the other hand, the greater the average frequency change during arousals and the more spontaneous arousals, the better was daytime vigilance. Our findings show that, in contrast to the lengthy Multiple Sleep Latency (MSLT) and Maintenance of Wakefulness (MWT) tests which evaluate sleep pressure under resting conditions conducive to sleep, V-EEG mapping provides a brief objective measure of a sleep apnea patient's daytime tiredness under conditions of wakefulness more appropriate to reflect the patient's everyday life.

Use of the respiration activity of Thiobacillus ferrooxidans for the specific determination of iron(II, III).

A method is described for the determination of Fe2+ and Fe3+ after its reduction to Fe2+ on the basis of oxygen uptake rate as a function of Fe2+ concentration. By using substrate-specific Thiobacillus ferrooxidans in combination with the standard addition method a specific determination of iron(II, III) is possible with the determination limit of 3 mumol/L.

Application of capillary zone electrophoresis to study the properties of rhodanese from Acidithiobacillus ferrooxidans.

A new capillary zone electrophoretic method was applied to the assay of enzymic activity of rhodanese from Acidithiobacillus ferroxidans. The enzyme activity determined by capillary zone electrophoresis was compared with that determined by discontinuous spectrophotometry, the values obtained being in good agreement. The method was also used to evaluate Michaelis constants of cyanide and thiocyanate as substrates; a new approach was developed to solve the problem with variable ionic strength of the samples. The pH and temperature optima for the enzyme were also determined.

Characterization of the submerged growth of Moraxella bovis.

A submerged batch cultivation of Moraxella bovis in a medium containing enzymic casein hydrolyzate and supplemented with dialyzed ram blood was described. Up to the growth limitation the bacteria grew exponentially without a lag phase and with a doubling period of 64 min. During the exponential phase no significant decrease of viable cells and cell autolysis were observed. Amino acids were the limiting factor. At the end of growth glutamic acid, threonine and serine were detected at the lowest concentrations. Substrate limitation led to an irreversible decrease of the metabolic activity. Growth yield on oxygen was 2.3 X 10(9) cells per mg O2. The fraction of respiration required for growth-uncoupled processes was negligible. During the cultivation ammonia was produced and the pH increased but it was not the inhibitory factor. Respiration was not limited by oxygen at concentrations higher than 0.63 mumol O2 per L. Sufficient pili were produced.

Formation of iodinin by a strain of Acidithiobacillus ferrooxidans grown on elemental sulfur.

The presence of the pigment iodinin, an Acidithiobacillus ferrooxidans culture metabolite, was demonstrated after growth of bacteria on elemental sulfur. The structure of iodinin was confirmed by X-ray structure analysis; its physiological role is discussed.

Purification and some properties of thiosulfate dehydrogenase from Acidithiobacillus ferrooxidans.

Thiosulfate dehydrogenase was purified from Acidithiobacillus ferrooxidans using three purification steps. The purification procedure involved ammonium sulfate fractionation, ion-exchange chromatography, and gel permeation chromatography. Specific activity of the purified enzyme (after IEC) was 3.26 nkat/mg, and yield of the enzyme was 78%. The purity of the enzyme was checked by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The enzyme is a tetramer composed of four probably identical subunits of relative molecular weight 45,000. The pH optimum of the enzyme reaction in the direction of substrate oxidation was found to be 3.0. The isoelectric point of the enzyme was 8.3. Enzyme activity was found to be particularly sensitive to the histidine-selective reagent diethylpyrocarbonate. Reagents selective for arginine, cysteine, and tryptophane had no effect on enzyme activity.

Characterization of hepatic and brain metabolism in young adults with glycogen storage disease type 1: a magnetic resonance spectroscopy study.

In glycogen storage disease type 1 (GSD1), children present with severe hypoglycemia, whereas the propensity for hypoglycemia may decrease with age in these patients. It was the aim of this study to elucidate the mechanisms for milder hypoglycemia symptoms in young adult GSD1 patients. Four patients with GSD1 [body mass index (BMI) 23.2 +/- 6.3 kg/m, age 21.3 +/- 2.9 yr] and four healthy controls matched for BMI (23.1 +/- 3.0 kg/m) and age (24.0 +/- 3.1 yr) were studied. Combined (1)H/(31)P nuclear magnetic resonance spectroscopy (NMRS) was used to assess brain metabolism. Before and after administration of 1 mg glucagon, endogenous glucose production (EGP) was measured with d-[6,6-(2)H(2)]glucose and hepatic glucose metabolism was examined by (1)H/(13)C/(31)P NMRS. At baseline, GSD1 patients exhibited significantly lower rates of EGP (0.53 +/- 0.04 vs. 1.74 +/- 0.03 mg.kg(-1).min(-1); P < 0.01) but an increased intrahepatic glycogen (502 +/- 89 vs. 236 +/- 11 mmol/l; P = 0.05) and lipid content (16.3 +/- 1.1 vs. 1.4 +/- 0.4%; P < 0.001). After glucagon challenge, EGP did not change in GSD1 patients (0.53 +/- 0.04 vs. 0.59 +/- 0.24 mg.kg(-1).min(-1); P = not significant) but increased in healthy controls (1.74 +/- 0.03 vs. 3.95 +/- 1.34; P < 0.0001). In GSD1 patients, we found an exaggerated increase of intrahepatic phosphomonoesters (0.23 +/- 0.08 vs. 0.86 +/- 0.19 arbitrary units; P < 0.001), whereas inorganic phosphate decreased (0.36 +/- 0.08 vs. -0.43 +/- 0.17 arbitrary units; P < 0.01). Intracerebral ratios of glucose and lactate to creatine were higher in GSD1 patients (P < 0.05 vs. control). Therefore, hepatic defects of glucose metabolism persist in young adult GSD1 patients. Upregulation of the glucose and lactate transport at the blood-brain barrier could be responsible for the amelioration of hypoglycemic symptoms.

Spatio-temporal regulation of mitogen-activated protein kinase (MAPK) signalling by protein phosphatases.

ERK (extracellular-signal-regulated kinase) is a MAPK (mitogen-activated protein kinase), which regulates diverse physiological functions including cell proliferation, differentiation, transformation and survival. It is now clear that in addition to the duration and magnitude of signalling through this MAPK pathway, the spatial restriction of MAPK activity plays a key role in determining the physiological outcome of signalling. Recent work has led to the discovery of MAPK-binding proteins, which contain either nuclear localization signals or nuclear export signals. These include MAPK activators and specific protein phosphatases, which may act to both regulate MAPK activity and the subcellular localization of their substrate. This represents a mechanism by which signalling in response to extracellular stimuli may be modulated in terms of both magnitude/duration and spatial restriction thus allowing differential access of the activated MAPK to target proteins and the interpretation of this information by cells to determine an appropriate physiological response.

Differential glucocorticoid effects on proliferation and invasion of human trophoblast cell lines.

Several clinical situations require continuous glucocorticoid (GC) treatment during pregnancy. A well-known deleterious side effect of such treatment is the higher incidence of growth-restricted fetuses, for which a too shallow trophoblast invasion is presently hypothesised as the underlying cause. This study investigated whether the synthetic GC triamcinolone acetonide (TA) influences proliferation, invasion and endocrine activity of human trophoblast. BeWo and JEG-3 choriocarcinoma cell lines both express GC receptors (western blotting) and were used as models for human trophoblast. JAR devoid cells of GC receptor were used as negative control. The cells were cultured for 48 h without (control) or with 0.5, 5 and 50 microM TA. In the presence and absence of serum, proliferation was determined by cell counting and measuring the cell cycle regulating protein cyclin B1 (Western blotting); invasion was determined by a conventional Matrigel invasion assay and by measuring the secretion (ELISA) of matrix-metalloproteinases (MMP-2, MMP-9) into the culture medium; endocrine activity was assessed by measuring the levels of human chorionic gonadotropin (ELISA) into the culture medium. TA altered the number of viable and dead cells as well as cyclin B1 levels and, to a lesser extent, invasion of BeWo and JEG-3, with a strong influence of serum. BeWo and JEG-3 cells reacted differently and in most instances reverse. In the cell lines used as models of human trophoblast, TA alter some functions relevant to proliferation and invasion, and suggest that caution should be exercised when treating women with GCs during pregnancy.

Comparison of once daily mometasone furoate (Nasonex) and fluticasone propionate aqueous nasal sprays for the treatment of perennial rhinitis. 194-079 Study Group.

BACKGROUND: Mometasone furoate (Nasonex), in a new once-daily aqueous nasal spray formulation, has been shown to be as effective and well-tolerated as twice-daily beclomethasone dipropionate aqueous nasal spray in treating symptoms of seasonal allergic rhinitis and perennial rhinitis. OBJECTIVE: To compare the effectiveness and tolerability of mometasone furoate to placebo and of fluticasone propionate aqueous nasal spray, all treatments administered once-daily, in patients with perennial rhinitis. METHODS: This was a 3-month, randomized, double-blind, double dummy, parallel group study in 550 patients, aged 12 to 77 years, at 25 centers in Canada, Latin America, and Europe. Patients allergic to at least one perennial allergen, with confirmed allergy history, skin test positivity, and moderate to severe symptomatology, were eligible to receive one of the following treatments, once daily in the morning: mometasone furoate 200 micrograms, fluticasone propionate 200 micrograms, or placebo. The primary efficacy variable was the change from baseline in total AM plus PM diary nasal symptom score over the first 15 days of treatment. RESULTS: Four hundred fifty-nine patients were valid for efficacy. For the primary efficacy variable, mometasone furoate was significantly (P < .01) more effective than placebo and was not statistically different from fluticasone propionate (percent reductions from baseline were 37, 39, and 22 for mometasone furoate, fluticasone propionate, and placebo, respectively). Generally, similar trends were seen for physician-evaluated total nasal symptoms, and patient-rated and physician-rated overall condition and response to therapy. Overall, mometasone furoate was at least as effective as fluticasone propionate at equivalent doses. There was no evidence of tachyphylaxis. All treatments were well tolerated. CONCLUSION: Mometasone furoate and fluticasone propionate adequately controlled symptoms of perennial rhinitis and were well tolerated.

Comparison of once daily mometasone furoate (Nasonex) and fluticasone propionate aqueous nasal sprays for the treatment of perennial rhinitis. The 194-079 Study Group.

BACKGROUND: Mometasone furoate (Nasonex), in a new once-daily aqueous nasal spray formulation, has been shown to be as effective and well-tolerated as twice-daily beclomethasone dipropionate aqueous nasal spray in treating symptoms of seasonal allergic rhinitis and perennial rhinitis. OBJECTIVE: To compare the effectiveness and tolerability of mometasone furoate to placebo and to fluticasone propionate aqueous nasal spray, all treatments administered once-daily, in patients with perennial rhinitis. METHODS: This was a 3-month, randomized, double-blind, double dummy, parallel group study in 550 patients, aged 12 to 77 years, at 25 centers in Canada, Latin America, and Europe. Patients allergic to at least one perennial allergen, with confirmed allergy history, skin test positivity, and moderate to severe symptomatology, were eligible to receive one of the following treatments, once daily in the morning: mometasone furoate 200 micrograms, fluticasone propionate 200 micrograms, or placebo. The primary efficacy variable was the change from baseline in total AM plus PM diary nasal symptom score over the first 15 days of treatment. RESULTS: Four hundred fifty-nine patients were valid for efficacy. For the primary efficacy variable, mometasone furoate was significantly (P < .01) more effective than placebo and was not statistically different from fluticasone propionate (percent reductions from baseline were 37, 39, and 22 for mometasone furoate, fluticasone propionate, and placebo, respectively). Generally, similar trends were seen for physician-evaluated total nasal symptoms, and patient-rated and physician-rated overall condition and response to therapy. Overall, mometasone furoate was at least as effective as fluticasone propionate at equivalent doses. There was no evidence of tachyphylaxis. All treatments were well tolerated. CONCLUSION: Mometasone furoate and fluticasone propionate adequately controlled symptoms of perennial rhinitis and were well tolerated.

Acquired chronic candidiasis treated with transfer factor.

A patient with acquired chronic oral and vaginal candidiasis resistant to topical and parenteral therapy was found to have impaired cell mediated immunity to Candida antigen and loss of skin test response to tuberculin (Mantoux). Treatment with Candida-active transfer factor produced clinical remission lasting 1 year and restitution of in vitro and in vivo immune parameters. Relapse occurred while receiving a second lot of transfer factor from the same donor. Subsequent treatment with levamisole was associated with onset of agranulocytosis.