Real-time organic aerosol chemical speciation in the indoor environment using extractive electrospray ionization mass spectrometry

Understanding the sources and composition of organic aerosol (OA) in indoor environments requires rapid measurements, since many emissions and processes have short timescales. However, real-time molecular-level OA measurements have not been reported indoors. Here, we present quantitative measurements, at a time resolution of five seconds, of molecular ions corresponding to diverse aerosol-phase species, by applying extractive electrospray ionization mass spectrometry (EESI-MS) to indoor air analysis for the first time, as part of the highly instrumented HOMEChem field study. We demonstrate how the complex spectra of EESI-MS are screened in order to extract chemical information and investigate the possibility of interference from gas-phase semivolatile species. During experiments that simulated the Thanksgiving US holiday meal preparation, EESI-MS quantified multiple species, including fatty acids, carbohydrates, siloxanes, and phthalates. Intercomparisons with Aerosol Mass Spectrometer (AMS) and Scanning Mobility Particle Sizer suggest that EESI-MS quantified a large fraction of OA. Comparisons with FIGAERO-CIMS shows similar signal levels and good correlation, with a range of 100 for the relative sensitivities. Comparisons with SV-TAG for phthalates and with SV-TAG and AMS for total siloxanes also show strong correlation. EESI-MS observations can be used with gas-phase measurements to identify co-emitted gas- and aerosol-phase species, and this is demonstrated using complementary gas-phase PTR-MS observations.     

Effects of vasodilators and perfusion pressure on coronary flow and simultaneous release of nitric oxide from guinea pig isolated hearts

OBJECTIVE: The aims were to validate the use of a direct reading NO electrode, to compare the effects of diverse acting drugs on altering coronary flow (CF) and NO release, and to examine the effects of altered perfusion pressure on flow-induced changes in NO concentration [NO] in the hemoglobin free effluent of guinea pig isolated hearts. METHODS: Hearts were isolated and perfused initially at a constant perfusion pressure (55 mmHg) with a modified Krebs-Ringer's solution equilibrated with 97% O2 and 3% CO2 at 37 degrees C. Heart rate, left ventricular pressure, CF, and effluent pH, pCO2, pO2, and NO generated current were monitored continuously on-line. Effluent was sampled for L-citrulline. Percent O2 extraction and O2 consumption were calculated. [NO] was quantitated with a sensitive amperometric sensor (sensitivity > or = 1 nmol/l approximately 3 pA) and a selective gas permeable membrane. RESULTS: The electrode was not sensitive to changes in solution pO2, flow, or pressure. The electrode was sensitive to pCO2 (-0.50 nmol/l/mmHg) and temperature (+24.5 nmol/l/degree C), so coronary effluent pCO2 was measured to compensate for a small decrease in pCO2 that occurred with an increase in coronary flow, and effluent temperature was rigidly controlled. Serotonin, bradykinin, and nitroprusside increased NO release along with CF, whereas nifedipine, butanedione monoxime, zaprinast, and bimakalim comparably increased CF but did not increase [NO] or NO release. Increases in CF (ml/g/min) and NO release (pmol/g/min), respectively, were 5.0 +/- 1 and 100 +/- 17 for 1 mumol/l serotonin, 7.5 +/- 1 and 148 +/- 18 for 100 nmol/l bradykinin, and 7.8 +/- 1 and 173 +/- 28 for 100 mumol/l nitroprusside. The increases in effluent NO by bradykinin were proportional to the increases in L-citrulline. Tetraethylammonium decreased CF, but did not change NO release, indomethacin changed neither CF nor NO release, and NG-nitro-L-arginine methyl ester (L-NAME) reduced CF by 2.6 +/- 1 ml/g/min and NO release by 25 +/- 8 pmol/g/min. An increase of CF of 8.0 +/- 0.3 ml/g/min, produced by increasing perfusion pressure from 25 to 90 mmHg, increased [NO] by 30 +/- 4 nmol/l; L-NAME but did not reduce the pressure-induced increase in CF, but reduced the increase in [NO] to 10 +/- 5 nmol/l. CONCLUSIONS: This study demonstrates in intact hearts real-time release of NO by several vasodilator drugs and by pressure-induced increases in flow (shear stress) and attenuation of these effects by L-NAME.     

Chronic fluoride exposure does not cause detrimental, extraskeletal effects in nutritionally deficient rats

On the basis of observations that endemic fluorosis occurs more often in malnourished populations, a series of studies tested the hypothesis that deficient dietary intake of calcium, protein or energy affects fluoride metabolism so that the margin of safe fluoride exposure may be reduced. The objective of the investigation was to determine whether changes in fluoride metabolism in nutritionally deficient rats resulted in manifestation of any extraskeletal toxic fluoride effects not observed in healthy animals. This investigation included two studies, one that monitored the effect of calcium deficiency on the effects of chronic fluoride exposure, and a second study that observed fluoride effects in rats that were deficient either in protein or in energy and total nutrient intake. Control and experimental rats received drinking water containing 0, 0.26 (5), 0.79 (15) or 2.63 (50) mmol fluoride/L (mg/L) for 16 or 48 wk. Control rats were fed optimal diets and experimental rats were fed diets deficient in calcium (Study 1) or protein (Study 2). An additional group of experimental rats (Study 2) was provided with a restricted amount of diet; thus these rats were deficient in energy and total nutrient intake. The intake, excretion and retention of fluoride were monitored; after the rats were killed, tissue fluoride levels and biochemical markers of tissue function were analyzed. Bone marrow cells were harvested from some of the rats, after 48 wk of treatment, for determining the frequency of sister chromatid exchange, a marker of genetic damage. Although there were significant differences among fluoride treatment groups in fluoride excretion and retention that resulted in significantly greater fluoride levels in tissues of the experimental rats, we were unable to detect any harmful, extraskeletal biochemical, physiologic or genetic effects of fluoride in the nutritionally deficient rats.     

A role for Edman degradation in proteome studies

Advances in protein database design and the software used to access the sequence data has led to progress in using protein attributes such as amino acid composition and peptide masses to identify proteins separated by two-dimensional electrophoresis. However, Edman degradation remains the principal technique for protein identification and it presents a significant bottleneck in the progress towards rapid protein identification. Simple modifications to the sequencing hardware, which automate the delivery of protein spots into the sequencer, and parallel sequencing of the protein spots represent a significant advance in the use of Edman degradation to rapidly generate the powerful protein attribute, an N-terminal sequence tag.     

Pigeon perception and discrimination of rapidly changing texture stimuli

The perception and discrimination of rapidly changing texture stimuli by pigeons was examined in a target localization task. Five experienced pigeons were rewarded for finding and pecking at a randomly placed odd target block of small repeated elements embedded in a larger rectangular array of contrasting distractor elements. On dynamic color test trials, the color of the target, distractor, or both of these regions changed at rates of 100, 250, 500, or 1000 ms per frame. The number of colors appearing within such trials also varied. Pigeons performed well above chance in all test conditions, with target-associated changes producing the best discrimination. The results suggest: (a) global relational information can exclusively guide target localization behavior, (b) pigeons can perceptually group and segregate colored textured differences quite rapidly (< or = 100 ms), and (c) pigeons may possess automatic search control processes that can be captured by stimulus-driven changes in the display.     

Analysis of immunoglobulin-synthesizing cells in human dental periapical lesions by in situ hybridization and immunohistochemistry

The iron status of 22 children and adolescents with Crohn's disease (mean age: 13 years) was evaluated. Eleven patients were suffering from active disease with inflammation, identified by at least one abnormal value for serum orosomucoid, C-reactive protein or sedimentation rate (group I). Eleven patients were in clinical remission and showed no biological evidence of inflammation (group II). Hemoglobin and red cell indices, erythrocyte protoporphyrin, serum iron, transferrin, serum ferritin and basic red cell ferritin were determined in all patients. The usual indicators of iron status, particularly serum ferritin, were affected by the inflammatory processes, but basic red cell ferritin appeared to be independent of inflammation. Basic red cell ferritin can therefore be considered to be a reliable indicator of iron status in children and adolescents with Crohn's disease.     

Translational research models in neuro-oncology

Tumor development and progression in the nervous system are poorly understood. Consequently, even though there seems to be little possibility of major advances in existing clinical modalities used to treat malignant brain tumors, no targeted molecular therapies have risen to take their place. The variability and plasticity of brain neoplasms make them an illusive target for study and therapeutic intervention. Further complicated by infiltration of vital nervous tissue, clinical studies have serious practical limitations and the ability to assess tumor progression in vivo is still a developing technology. Evaluation of potential new therapies for brain tumors is heavily dependent on the development of more informative and cognate experimental models. To develop and validate new models, it is particularly important to integrate clinical, pathological, and cell biological characterizations of malignant brain tumors. This discussion provides an overview of developments in tumor cell culture and the impact of animal models on brain tumor research. Studies of malignant glial neoplasms associated with a dismal prognosis in patients receive particular attention.     

Protein expression profiles in human breast ductal carcinoma and histologically normal tissue

Reference two-dimensional (2-D) gels are presented for human breast ductal carcinoma and histologically normal tissue. Whole biopsy fragments were analyzed, including epithelial and nonepithelial components. Thirty-five spots have been assigned by gel matching to the human liver SWISS-2DPAGE reference map and/or to the human primary keratinocyte IPG map from the Danish Center for Human Genome. N-terminal microsequencing was applied to confirm randomly chosen matching assignments and to identify six new spots. Protein expression profiles in ductal carcinoma and in normal breast tissue appeared to be similar, except for a pattern consisting of 32 spots, which were highly expressed in all carcinoma specimens, and less intense and occasionally undetectable in normal tissue. This difference was statistically significant. Assignment has been obtained for several spots, namely GRP94, GRP78, GRP75, mitochondrial HSP60, calreticulin, protein disulfide isomerase, peptidyl-prolyl cis-trans isomerase, collagen-binding protein 2, fructose bisphosphate aldolase, glyceraldehyde-3-phosphate dehydrogenase, thioredoxin, cytochrome c oxidase VA subunit, tubulin beta isoform and macrophage migration inhibitory factor (MIF). The cancer- and tissue-specificity of the described pattern was assessed by matching to the Swiss-2DPAGE human liver, hepatoma, lymphoma, erythroleukemia reference maps. The pattern of 32 spots was found to be indicative of epithelial neoplasia.