Using advanced mass spectrometry techniques to fully characterize atmospheric organic carbon: current capabilities and remaining gaps.

Organic compounds in the atmosphere vary widely in their molecular composition and chemical properties, so no single instrument can reasonably measure the entire range of ambient compounds. Over the past decade, a new generation of in situ, field-deployable mass spectrometers has dramatically improved our ability to detect, identify, and quantify these organic compounds, but no systematic approach has been developed to assess the extent to which currently available tools capture the entire space of chemical identity and properties that is expected in the atmosphere. Reduced-parameter frameworks that have been developed to describe atmospheric mixtures are exploited here to characterize the range of chemical properties accessed by a suite of instruments. Multiple chemical spaces (e.g. oxidation state of carbon vs. volatility, and oxygen number vs. carbon number) were populated with ions measured by several mass spectrometers, with gas- and particle-phase α-pinene oxidation products serving as the test mixture of organic compounds. Few gaps are observed in the coverage of the parameter spaces by the instruments employed in this work, though the full extent to which comprehensive measurement was achieved is difficult to assess due to uncertainty in the composition of the mixture. Overlaps between individual ions and regions in parameter space were identified, both between gas- and particle-phase measurements, and within each phase. These overlaps were conservatively found to account for little (<10%) of the measured mass. However, challenges in identifying overlaps and in accurately converting molecular formulas into chemical properties (such as volatility or reactivity) highlight a continued need to incorporate structural information into atmospheric measurements.

N2O5 reactive uptake on aqueous sulfuric acid solutions coated with branched and straight-chain insoluble organic surfactants.

A flow reactor coupled to a chemical ionization mass spectrometer was used to study the reactive uptake coefficients at 273 K of N2O5 on aqueous 60 wt % sulfuric acid solutions coated with insoluble organic monolayers. Both straight-chain surfactants (1-hexadecanol, 1-octadecanol, and stearic acid) and a branched surfactant (phytanic acid) were studied. The reactive uptake coefficient decreased dramatically for straight-chain surfactants. The decrease ranged from a factor of 17 to a factor of 61 depending on the type of straight-chain surfactant. In contrast to the straight-chain data, the presence of phytanic acid did not have a significant effect on the N2O5 reactive uptake coefficient (the decrease was less than the uncertainty in the data) compared to the uncoated solution. In addition to measuring the reactive uptake coefficients, we also investigated the relationship between properties of the monolayers and the reactive uptake coefficients. The reactive uptake coefficients measured on aqueous sulfuric acid subphases showed a relationship to the surface area occupied by the surfactant molecules. However, data obtained with other subphases did not overlap with this trend.

A novel flow reactor for studying reactions on liquid surfaces coated by organic monolayers: methods, validation, and initial results.

A new flow reactor has been developed that allows the study of heterogeneous kinetics on an aqueous surface coated by an organic monolayer. Computational fluid dynamics simulations have been used to determine the flow characteristics for various experimental conditions. In addition a mathematical framework has been developed to derive the true first-order wall loss rate coefficient, k(1st)(w), from the experimentally observed wall loss rate, k(obs). Validation of the new flow reactor is performed by measuring the uptake of O(3) by canola oil as a function of pressure and flow velocity and the reactive uptake coefficients of N(2)O(5) by aqueous 60 wt % and 80 wt % H(2)SO(4). Using this new flow reactor, we also determined the reactive uptake coefficient of N(2)O(5) on aqueous 80 wt % H(2)SO(4) solution coated with an 1-octadecanol (C(18)H(37)OH) monolayer. The uptake coefficient was determined as (8.1 +/- 3.2) x 10-4, which is about 2 orders of magnitude lower compared to the reactive uptake coefficient on a pure aqueous 80 wt % H(2)SO(4) solution. Our measured reactive uptake coefficient can be considered as a lower limit for the reactive uptake coefficient of aqueous aerosols coated with organic monolayers in the atmosphere, because in the atmosphere organic monolayers will likely also consist of surfactants with shorter lengths and branched structures which will have a smaller overall effect.

Dilated cardiomyopathy is associated with significant changes in collagen type I/III ratio.

BACKGROUND: It is controversial whether myocardial fibrosis in end-stage dilated cardiomyopathy (DCM) is associated with altered collagen type I/type III (Col I/Col III) ratio. METHODS AND RESULTS: Patients with DCM (ejection fraction [EF] <50%, n=12) and with mild global left ventricular dysfunction (EF >50%, n=18) were examined. Col I, Col III, and transforming growth factors-beta1 (TGF-beta1) and -beta2 (TGF-beta2) gene expression in endomyocardial biopsies was evaluated by quantitative competitive reverse transcriptase-polymerase chain reaction (qRT-PCR). Collagen content was quantified after picrosirius red and immunohistological staining and by hydroxyproline assay. In patients with EF <50%, there was a pronounced 2- to 6-fold increase of myocardial Col I mRNA abundance (P<0.01), with a corresponding 1.6-fold increase at the protein level versus that found in patients with EF >50%. The Col III mRNA abundance showed a 2.0-fold increase (P<0.04). There was a relevant shift in the Col I/Col III mRNA ratio for DCM patients (Col I/Col III, 8.2) compared with patients with an EF >50% (Col I/Col III, 6. 4). In addition, total collagen content was increased in patients with EF <50% (n=3) (4.3+/-0.1%) compared with patients with EF >50% (n=8) (2.7+/-0.9%) (P<0.004). The biochemically determined ratio of hydroxyproline/total protein (n=12) was correlated to the Col I mRNA abundance (P<0.05, r=0.77). TGF-beta1 and TGF-beta2 showed elevated myocardial mRNA abundances (1- to 7-fold and 4- to 5-fold, respectively) in DCM patients. CONCLUSIONS: Differential increase of Col I and Col III leads to an increased Col I/Col III ratio in DCM myocardium. Because Col I provides substantial tensile strength and stiffness, this may contribute to systolic and in particular diastolic dysfunction in DCM.

Performance-based management in local health departments: measuring the success of implementation.

Six of eight local health departments in North Carolina's Southwest Perinatal Region III participated in a PBMS demonstration project also involving the state health department, the Centers for Disease Control, and the School of Public Health of the University of North Carolina at Chapel Hill. In all six counties the problem of reducing prematurity and low birthweight was selected to test this innovation. Using standardized instruments, staff awareness of and concern for low birthweight problems and programs were measured, as was level of success of implementation of PBMS. Factor analysis of three rounds of Awareness and Concern responses produced three uncorrelated factors: awareness of low birthweight problems, awareness of low birthweight programs, and concern for low birthweight. The results suggest that the PBMS increased awareness of the problem and the program, and that the project succeeded in half of the counties, helped some counties achieve some goals, and provided some benefits to some counties. The implications for Total Quality Management are discussed.

Patient, parent, and physician perspectives on pediatric oncology rounds.

To provide data to guide physicians regarding the extent to which pediatric patients and their families should be involved in decision-making discussions by their health care teams, we compared the standard rounding procedure in a pediatric oncology unit (rounds conducted out of earshot) with bedside rounds in which management was discussed in front of patients and parents. Type of rounds was alternated in 2-week blocks for 4 months. The impact of the two types of rounds of 35 parents and children was studied. Parents preferred bedside rounds to standard rounds, and perceived increased opportunities to obtain information and ask questions. Parents and children differed in their reports of how much bedside rounds upset children. Older children, compared with younger children, more strongly disliked standard rounds; this appeared to be related to feelings of exclusion. The two types of rounds differed in their effectiveness in providing specific types of education to residents. The findings suggest that bedside rounds have a positive impact on parents' attitudes toward physicians, that they do not dilute the child's sense of relationship with the primary attending physician, and that they contribute to certain aspects of resident education.

Percutaneous hepatic biopsy in suspected pancreatic carcinoma.

Pancreatic neoplasms often present with hepatic lesions as well as a pancreatic mass, as seen on abdominal computed tomography examination. To obtain histologic diagnosis, we advocate computed tomography-directed biopsy of the liver lesion instead of the pancreatic mass because of the increased accuracy and safety of hepatic biopsy as compared with pancreatic biopsy.

Liver lesions: comparative accuracy of scintigraphy and computed tomography.

Of 84 cases with both radionuclide and computed tomographic studies of the liver, in 54 the results of the two examinations agreed, in 14 results disagreed, and in 16 cases one of the two tests gave equivocal results. Overall accuracy in detecting or ruling out focal liver disease was 79% for scintigraphy and 98% for computed tomography. In 13 of the 14 patients in whom studies did not agree, the scintigram was falsely negative. In 10 of these 13 false-negative scintigrams, small (less than 2 cm) solitary or multiple lesions were detected on computed tomography in patients who had normal liver function studies. In seven patients in whom both studies agreed, computed tomography provided additional, extrahepatic information that altered clinical management. Scintigraphy was 86% accurate in detecting liver disease when the patient had a gastrointestinal neoplasm, but only 74% accurate for nongastrointestinal neoplasm. Computed tomography was over 94% accurate in both situations. These data indicate an advantage of computed tomography as the initial screening examination for space-occupying lesions of the liver, especially in patients with a primary diagnosis of nongastrointestinal neoplasm.

Gas in the pancreatic bed without abscess.

A series of 259 patients from the Emory University Affiliated Hospitals with clinical suspicion of pancreatic inflammatory or neoplastic disease was reviewed. Seven of the patients had documented gas in a pancreatic mass; three of the cases were proved subsequently not to be pancreatic abscess formation. Two of the seven patients had proven fistulae from pseudocyst to bowel documented either by surgery or on an associated radiologic examination which accounted for the gas. In one additional patient, no fistula was identified at preoperative radiologic examination or at surgery. The awareness of this entity is important in the avoidance of unnecessary surgery. Since patients with spontaneous cystoenteric fistulae improve after rupture into the gastrointestinal tract, this entity should be kept in mind, particularly in the patient who is not toxic. Radiologic evaluation of the gastrointestinal tract to detect fistulous communication, percutaneous aspiration, and culture may prevent unnecessary surgery.