A systematic review of the contribution of qualitative research to the study of quality of life in children and adolescents with epilepsy.

A sizeable literature focusing on QOL in children and adolescents with epilepsy has been produced over the last few years. However, relatively little emphasis has been placed on defining these issues from direct exploration of children's and adolescents' views. Qualitative methodologies are proposed in this review as an appropriate means of eliciting such information. This review systematically investigated the extent to which studies of QOL in children and adolescents with epilepsy have used recognised qualitative methodology. Articles for inclusion were identified by searching the term 'epilepsy', combined with 'adolescent(s) and/or child(ren)' and 'psychosocial and/or quality of life'. Selected articles were reviewed and rated using CASP Guidelines for qualitative research by two independent raters. Seventeen studies were retrieved through literature search. Of these six used some form of qualitative methodology either individually or combined with quantitative methods. However, only one study met quality criteria for selection in this systematic review. A summary of both selected and excluded studies is presented and methodological limitations discussed. Recommendations for appropriate methodology for investigation of QOL issues in children and adolescents are given.

Quality of life and psychosocial development in adolescents with epilepsy: a qualitative investigation using focus group methods.

The majority of previous studies investigating the impact of epilepsy on the QOL of adolescents have used proxy opinions from clinicians and/or parents. This study highlights the need for research to investigate QOL from the direct perspective of adolescents and consider issues in the context of a developmental perspective. A focus group technique was used. Twenty-two adolescents aged between 12 years 4 months and 18 years 0 months (6 males and 16 females) were stratified by age (12-13, 14-15 and 16+ years) into six focus groups. Data were transcribed and QSR NUD*IST 4.0 was used to help generate central themes. Several procedures were undertaken to increase validity and reliability of findings. Analysis identified two main themes comprising (a) issues related to adolescent development (identity formation) and (b) epilepsy related variables, with five and four main sub-themes, respectively ('peer acceptance', 'development of autonomy', 'school related issues', 'epilepsy as part of me' and 'future', and 'medication issues', 'seizures', 'knowledge of epilepsy' and 'sense of uncertainty'). The main issues related to peer acceptance and development of autonomy. In contrast to previous studies, academic difficulties were not highlighted as an issue. No significant age-related differences in issues were identified. A conceptual model representing these findings is presented and clinical implications and suggestions for future research are reported.

Real-time, high-resolution quantitative measurement of multiple soil gas emissions: selected ion flow tube mass spectrometry.

A new technique is presented for the rapid, high-resolution identification and quantification of multiple trace gases above soils, at concentrations down to 0.01 microL L(-1) (10 ppb). The technique, selected ion flow tube mass spectrometry (SIFT-MS), utilizes chemical ionization reagent ions that react with trace gases but not with the major air components (N2, O2, Ar, CO2). This allows the real-time measurement of multiple trace gases without the need for preconcentration, trapping, or chromatographic separation. The technique is demonstrated by monitoring the emission of ammonia and nitric oxide, and the search for volatile organics, above containerized soil samples treated with synthetic cattle urine. In this model system, NH3 emissions peaked after 24 h at 2000 nmol m(-2) s(-1) and integrated to approximately 7% of the urea N applied, while NO emissions peaked about 25 d after urine addition at approximately 140 nmol m(-2) s(-1) and integrated to approximately 10% of the applied urea N. The monitoring of organics along with NH3 and NO was demonstrated in soils treated with synthetic urine, pyridine, and dimethylamine. No emission of volatile nitrogen organics from the urine treatments was observed at levels >0.01% of the applied nitrogen. The SIFT method allows the simultaneous in situ measurement of multiple gas components with a high spatial resolution of < 10 cm and time resolution <20 s. These capabilities allow, for example, identification of emission hotspots, and measurement of localized and rapid variations above agricultural and contaminated soils, as well as integrated emissions over longer periods.

Real time analysis of breath volatiles using SIFT-MS in cigarette smoking.

The selected ion flow tube mass spectrometry (SIFT-MS) technique enables real time analysis of trace volatiles at ppb levels without preconcentration steps or chemical derivatization. Most previous studies of trace compounds on the breath were analyzed using gas chromatography where enhanced detection sensitivity was achieved by concentrating the breath using cryogenic or adsorption trapping techniques. In this paper, we have examined volatile organic substances, isoprene, acetone, ammonia and ethanol in breath before and after smoking a cigarette. It is interesting that isoprene levels increased in all the subjects after smoking one cigarette with a mean increase of 70%. The mean increase for acetone was found to be 22%. In contrast to isoprene, a decreasing ethanol level was observed in all the subjects except one with the negative mean decrease of 28%. Further SIFT-MS studies also have high-lighted some organic substances produced even by unburned cigarettes, US and New Zealand products. Certain US brands have shown much higher levels of volatile species than cigarettes produced in New Zealand.

Termolecular ion-molecule reactions in Titan's atmosphere. II: the structure of the association adducts of HCNH+ with C2H2 and C2H4.

The ion-molecule reactivity of the products formed in the association reactions of HCNH+ with C2H2 (C3H4N+) and C2H4 (C3H6N+) has been investigated to provide information on the structures of the adducts thus formed. The C3H4N+ and C3H6N+ adducts were formed in the reaction flow tube of a flowing afterglow sourced-selected ion flow tube (FA-SIFT) and their reactivity with a neutral molecular "probe" examined. The reactivity of possible known structural isomers for the C3H4N+ and C3H6N+ ions was investigated in both the FA-SIFT and an ion cyclotron resonance spectrometer (ICR). Ab initio investigations of the potential energy surfaces for both structures at the G2(MP2) level have also been performed and structures corresponding to local minima on both surfaces have been identified and evaluated. The results of these experimental and theoretical studies show that at room temperature, the C3H4N+ adduct ion contains two isomers; a less reactive one that is likely to be a four-membered cyclic covalent isomer (approximately 70%) and a faster reacting component that is probably an electrostatic complex (approximately 30%). The C3H6N+ adduct ion formed from HCNH+ + C2H4 at room temperature is a single isomer that is likely to be the four-membered covalently bound cyclic CH2CH2CHNH+ species.

Alcohol in breath and blood: a selected ion flow tube mass spectrometric study.

In this paper we compare the amounts of ethanol in breath and in blood after ingestion of whisky using analysis by selected ion flow tube mass spectrometry (SIFT-MS). Blood ethanol concentrations were also obtained using standard hospital forensic procedures for blood alcohol analyses. We demonstrate the quantitative nature of SIFT-MS analysis by correlating the observed alcohol content of the headspace above 5-mL amounts of venous blood and aqueous solution to which known trace amounts of alcohol have been added. This procedure provides a Henry's Law coefficient for ethanol in aqueous solution at 298 +/- 3 K of 209 +/- 7 mol/kg*bar. We also demonstrate that measurement of the ethanol concentration in the alveolar portion of a single breath using the SIFT-MS technique gives an accurate measure of blood alcohol and could obviate the need for blood samples in forensic processing. The storage performance of breath samples in Mylar bags with a volume greater than 1 L has been shown to maintain the mixture integrity for ethanol but not for some other species.

Quantitative analysis of trace gases of breath during exercise using the new SIFT-MS technique.

We show how the concentration of the breath gases ammonia, acetone, and isoprene vary with time during exercise using the new selected ion flow tube mass spectrometry (SIFT-MS) technique. The expired breath concentrations of ammonia, acetone and isoprene were observed within the range of 50-500, 100-1400 and 5-400 ppb, respectively. Increasing acetone levels were observed for most subjects during the exercise period. However, isoprene levels decreased with time during exercise. Older subjects showed higher levels of isoprene compared with younger subjects. The ammonia time profile with exercise showed both decreasing and increasing patterns for different subjects.

Association reactions at low pressure. III. The C2H2+/C2H2 system.

The association reactions, C4H2(+) + C2H2 and C4H3(+) + C2H2 have been examined at pressures between 8 x 10(-8) and 1 x 10(-4) Torr at 298 K in an ion cyclotron resonance mass spectrometer. Association occurred via two different mechanisms. At pressures below approximately 2 x 10(-6) Torr, the association was bimolecular having rate coefficients k2 = 2.7 x 10(-10) cm3 s-1 and 2.0 x 10(-10) cm3 s-1 for C4H2+ and C4H3+, respectively. At pressures above approximately 2 x 10(-6) Torr, termolecular association was observed with rate coefficients, k3 = 5.7 x 10(-23) cm6 s-1 and 1.3 x 10(-23) cm6 s-1 for C4H2+ and C4H3+, respectively, when M = C2H2. The termolecular rate constants with N2, Ar, Ne, and He as the third body, M, are also reported. We propose that the low pressure bimolecular association process was the result of radiative stabilization of the complex and the termolecular association process was the result of collisional stabilization. Elementary rate coefficients were obtained and the lifetime of the collision complex was > or = 57 microseconds for (C6H4+)* and > or = 18 microseconds for (C6H5+)*. At pressures below 1 x 10(-6) Torr, approximately 11% of the (C6H4+)* were stabilized by photon emission and the remaining approximately 89% reverted back to reactants, while approximately 24% of the (C6H5+)* were stabilized by photon emission and the remaining approximately 76% reverted back to reactants. The ionic products of the C2H2(+) + C2H2 reaction, C4H2+ and C4H3+, were found to be formed with enough internal energy that they did not react by the radiative association channel until relaxed by several nonreactive collisions with the bath gas.

Structural isomers of C2N+: a selected-ion flow tube study.

Reactivities of the structural isomers CCN+ and CNC+ were examined in a selected-ion flow tube at 300 +/- 5 K. The less reactive CNC+ isomer was identified as the product of the reactions of C(+) + HCN and C(+) + C2N2; in these reactions only CNC+ can be produced because of energy constraints. Rate coefficients and branching ratios are reported for the reactions of each isomer with H2, CH4, NH3, H2O, C2H2, HCN, N2, O2, N2O, and CO2. Ab initio calculations are presented for CCN+ and CNC+; a saddle point for the reaction CCN+ --> CNC+ is calculated to be 195 kJ mol-1 above the CNC+. The results provide evidence that the more reactive CCN+ isomer is unlikely to be present in measurable densities in interstellar clouds.