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At least 253 records · Page 14Linked to original sources

L.A. stories: aggression in preschoolers' spontaneous narratives after the riots of 1992.

64 inner-city preschoolers' spontaneous story narratives that were examined directly after the Los Angeles riots of 1992 were compared with narratives told by a matched comparison group of 128 children living in other U.S. cities who had no direct exposure to the riots. Narratives were coded for length, complexity, overall thematic content, character behavior in the stories, number of aggressive words, and story outcome. Children were given language and pre-academic skill assessments, their classroom behavior was observed and teachers rated children's social competence. Results indicated that there were significant group differences in the story narratives. Children who were directly exposed to the riots told more narratives with aggressive thematic content, aggressive words, unfriendly figures who engaged in physical aggression, and mastery of situations with aggression than did the comparison group of children who had no direct exposure to the riots. The findings suggest that children's narratives reflected their exposure to the violence and their expression of that experience.

Aggression↗

Observation of different ceramide species from crude cellular extracts by normal-phase high-performance liquid chromatography coupled to atmospheric pressure chemical ionization mass spectrometry.

Normal-phase high-performance liquid chromatography (NP-HPLC) coupled to atmospheric pressure chemical ionization mass spectrometry (APCI-MS) allows qualitative analysis of endogenous ceramide and dihydroceramide species from crude lipid extracts utilizing chromatographic methods readily adaptable from commonly used thin layer chromatography (TLC) conditions. Qualitative information for the species comes from observation of differences in chromatographic and mass spectrometric behavior between species. Application to the analysis of ceramide and dihydroceramide from various cell lines is demonstrated. The results show the species profile in each cell line to be unique despite growth under identical conditions. The results from APCI-MS analysis corroborate and enhance information acquired from use of the diacylglycerol kinase assay for total ceramide measurement. This technique readily allows the previously difficult distinction between ceramide and dihydroceramide species.

Atmospheric Pressure↗

Double-mode impedance analysis of epithelial cell monolayers cultured on shear wave resonators.

The viscoelastic behavior of epithelial cells (MDCK-I and MDCK-II) grown on AT-cut quartz crystals with a fundamental resonance at 5 MHz was investigated by impedance spectroscopy. Using the electromechanical model recently derived by Martin et al. [(1991) Anal Chem 63: 2272-2281] for Newtonian liquids in contact with shear wave resonators we quantified the viscous damping arising from the adherent cells by fitting the impedance data with a modified Butterworth-Van Dyke circuit in the region of the resonance frequency. Impedance spectroscopy was additionally performed in the frequency range from 1 Hz to 1 MHz to scrutinize the passive electrical properties of the epithelial cell layers using an additional platinum electrode. These data allow one to document the cell layers' integrity as well as the electrode coverage. We were able to confirm that the presence of a cell-layer mainly increases damping of the shear wave and does not exhibit a pure mass-load behavior. These findings were supported by the discovery that the inductance L in the electromechanical model was less influenced by the cell-layer than the resistance R. The apparent cell-viscosities determined by our method are 0.097 poise for MDCK-I and 0.142 poise for MDCK-II cell-layers. These low apparent viscosities may be explained in terms of a considerable spacing between the cells immobilized via their focal contacts and the quartz surface.

Animals↗

alpha-Methyldopamine, a key intermediate in the metabolic disposition of 3,4-methylenedioxyamphetamine in vivo in dog and monkey.

Metabolites of 3,4-methylenedioxyamphetamine in the urine of dogs and monkeys were separated by gas-liquid chromatography as their trifluoroacetyl and/or n-butyl ether derivatives and identified by comparison of the chromatographic and mass spectrometric behavior of these derivatives with those of synthetic compounds. The metabolites identified in dog and monkey urine were alpha-methyldopamine, 3-O-methyl-alpha-methyldopamine, and 3,4-dihydroxybenzyl methyl ketone. The monkey urine also contained 3,4-methylenedioxybenzyl methyl ketone and 3,4-methylenedioxybenzoic acid present as a glucuronide and/or sulfate conjugate, whereas the dog urine had 3-methoxy-4-hydroxybenzoic acid present as a conjugate other than glucuronide and sulfate. The phenolic metabolites in both species were present free and as glucuronide and/or sulfate conjugates.

3,4-Methylenedioxyamphetamine↗

Nanoelectrospray--more than just a minimized-flow electrospray ionization source.

The comparison between electrospray ionization (ESI) mass spectra from NaCl solutions with and without analyte obtained under ionspray and nanospray conditions reveals different mass spectral behavior of the two ESI techniques. This can be attributed to the different initial droplet sizes which are in the microns range for ionspray, while in nanospray they are believed to be about one order of magnitude smaller. In the context of the widely accepted uneven-fission model, nanospray would then enter one fission generation later; in addition, a higher initial droplet surface charge density in nanospray results in early fissions without extensive evaporation and thus increase in sample and salt concentration. This rationalizes that ionspray spectra closely resemble nanospray spectra from solutions with about one order of magnitude higher salt concentrations, showing a higher tolerance of nanospray towards salt contamination. When the analyte is a peptide (in a solution containing a high molar surplus of salt), molecule ion formation effectively competes with salt cluster ion formation; when the analyte is a sugar, it is detectable beside a high salt concentration only with nanospray, indicating the supporting effect of surface activity on ion release in the case of peptides. A model is presented which explains the different mass spectral behaviour of ionspray and nanospray by suggesting different "predominant fission pathways" depending on the size of the initial droplets.

Algorithms↗

Negative-ion electrospray ionization mass spectrometry of N-benzyloxycarbonyl-protected 1-substituted and cyclic taurines.

The negative-ion mass spectrometric behavior of N-benzyloxycarbonyl-protected 1-substituted and cyclic taurines has been investigated under electrospray ionization conditions. Their fragmentation pathways are proposed and supported by collisionally activated dissociation product-ion spectrometry. The deprotonated substituted taurines preferentially eliminate a molecule of benzyl alcohol to yield isocyanato-sulfonate ions, which further generate alkene-2-sulfonate ions by loss of isocyanic acid. The isocyanato-sulfonate ions of 1-substituted taurines could further generate aziridine-2-sulfonate ion via ring rearrangements by loss of CO plus benzyne and carbene moieties, respectively, while the isocyanato-sulfonate ions of cyclic taurines could further give rise to cycloalkene anion radicals. An obvious substituent effect on the fragmentations of the title compounds was observed.

Cyclopentanes↗

Suicide and the media.

Evidence continues to amass on the significant impact of media coverage on suicide. The research literature on the impact of news reports of nonfictional suicides as well as fictional suicide stories is reviewed in order to determine the nature and scope of the influence of the mass media on suicide. The current review, building upon earlier reviews, is limited to English language publications or English translations of articles and/or abstracts. The interactive factors that may moderate the impact of media stories are also reviewed. Such interactive factors include characteristics of the stories (agent), individuals' attributes (host), and social context of the stories (environment). Recommendations are presented for the reporting of suicide stories, which may minimize the risk of imitative suicides. The media's positive role in educating the public about risks for suicide and shaping attitudes about suicide is emphasized. In summary, the existence of suicide contagion no longer needs to be questioned. We should refocus our research efforts on identifying which particular story components promote contagion under which circumstances and which components are useful for preventive programming.

Humans↗

Living with support in a home in the community: predictors of behavioral development and household and community activity.

The purpose of this article was to review studies of behavioral development and household and community activity among adults with mental retardation living in community residential services and to distill knowledge about the factors that influence outcome. Research points to behavioral development occurring across the full spectrum of disability but influenced by mental retardation syndrome and the acquisition of pivotal skills. However, engagement in household and community activities has been found to be strongly related to individual adaptive behavior. People with more severe mental retardation are vulnerable to leading lives characterized by underoccupation and lack of community involvement. Moving from institutional to community-based residential services may be accompanied by significant increases in adaptive behavior, but a plateau effect on subsequent development has also been reported. There is substantial evidence to suggest that key aspects of effective teaching technology may be absent in community-based residential environments. Community settings support greater engagement in household and community activities than institutions. Ordinary housing stock and normative architecture and standards of material enrichment are to be preferred. The use of normative housing constrains group living to relatively small scale, but there is little evidence that smaller size within this range is to be preferred to larger size. There is little evidence to suggest that higher staff-to-resident ratios lead to uniformly better outcomes, but staff orientation, working methods, and performance are important influences. Little is known about what precise characteristics of community location give rise to greater community integration. MRDD Research Reviews 7:75-83, 2001.

Adaptation, Psychological↗

A model-free method for mass spectrometer response correction.

A new method for correction of mass spectrometer output signals is described. Response-time distortion is reduced independently of any model of mass spectrometer behavior. The delay of the system is found first from the cross-correlation function of a step change and its response. A two-sided time-domain digital correction filter (deconvolution filter) is generated next from the same step response data using a regression procedure. Other data are corrected using the filter and delay. The mean squared error between a step response and a step is reduced considerably more after the use of a deconvolution filter than after the application of a second-order model correction. O2 consumption and CO2 production values calculated from data corrupted by a simulated dynamic process return to near the uncorrupted values after correction. Although a clean step response or the ensemble average of several responses contaminated with noise is needed for the generation of the filter, random noise of magnitude less than or equal to 0.5% added to the response to be corrected does not impair the correction severely.

Cardiac Output↗

Preparation, gas chromatography and mass spectrometry of methyl and trimethylsilyl esters of indomethacin.

The preparation and gas chromatographic-mass spectrometric behavior of the methyl and trimethylsilyl esters of indomethacin, 1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetic acid, are described. Reaction of this anti-inflammatory drug with diazomethane or bis(trimethylsilyl)acetamide forms the expected esters. Derivatization with dimethylformamide dimethylacetal yields two compounds, the methyl ester (major product) and a methyl ester-dimethylaminomethylene condensation (at the alpha-carbon of the side chain) product (minor). Experiments with 5-O-desmethyl-indomethacin have demonstrated that using the described diazomethane methylation conditions no alkylation of the phenolic group occurs. Esterification combined with an isolation procedure allows the determination of indomethacin levels in plasma and aqueous humor of rabbits, the 4-fluorobenzoyl analog serving as internal standard. The derivatives exhibit excellent electron capture properties allowing quantitative assay of the drug at the submicrogram level. Precision and accuracy for plasma samples varied from 92 +/- 19% (5 ng/ml) to 96 +/- 1.5% (1000 ng/ml). The analogous values for aqueous humor are superior: 97 +/- 5.6% and 99 +/- 2.2%, resectively.

Chromatography, Gas↗

Electron ionization mass spectra of phosphorus-containing heterocycles. II. 1,2,3,4,4a,5,6,7,8,8a-decahydro-1,3,2-benzodiazaphosphinine 2-oxides.

The electron ionization mass spectra of cis- and trans-fused 1,2,3,4,4a,5,6,7,8,8a-decahydro-1,3,2-benzodiazaphosphinine 2-oxides (1-17) were recorded, and the fragmentation pathways were established and compared with those of 1,4,4a,5,6,7,8,8a-octahydro-2H-3,1,2-benzoxazaphosphinine 2-oxides. In general, the mass spectral behaviors of the isomeric compounds were very similar and it was mostly impossible to differentiate them from each other on the basis of the relative abundances of their characteristic fragment ions. The compounds in which R(2) = Ph or OPh exhibited a series of common fragments, e.g. [R(2)H](+), R(2)PONHR(1(3)+), [M-C(3)H(7)](+) and [M-C(4)H(9)](+), the latter two ions being present in the spectra of only two of the derivatives with an N(CH(2)CH(2)Cl)(2) substituent on the P atom. When R(2) = Ph, numerous other alkyl radicals, alkenes and a cycloalkane were also ejected and these compounds also lost NH(2), NH(3), CH(3)N, CH(4)N or CH(3)NH(2). The compounds with an N(CH(2)CH(2)Cl)(2) substituent on the P atom most closely resembled their 3,1,2-O,N,P analogs in respect of the dominant role of this substituent.

Alkenes↗

Study of 4-quinolone antibiotics in biological samples by short-column liquid chromatography coupled with electrospray ionization tandem mass spectrometry.

Simultaneous detection and confirmation of 15 quinolone antibiotics was accomplished by fast short-column liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC/MS/MS). Several physiochemical parameters such as hydrophobicity and aqueous dissociation constants were calculated from the structural formulas of the quinolone drugs, and their impact on both chromatographic and mass spectrometric behavior was studied. Additionally, a possible influence of bulk solution pH on electrospray detection sensitivity of 4-quinolones was investigated and compared to predictions based on solution-phase equilibria. A signal intensity comparison of the MH+ ions at different pH values for all 15 compounds did not reveal any pH effect, despite variations by several orders of magnitude in equilibrium concentrations in bulk solution. To demonstrate the potential of the LC/MS/MS method, its application to trace analysis in several biological matrices such as milk, salmon, and human urine was investigated. The method was shown to be sensitive with detection limits down to 1 ppb in both milk and salmon tissue. The versatility of the method was also exhibited by utilizing it for rapid identification of urinary metabolites of ciprofloxacin. Finally, a new complementary approach is described for confirmatory analyses of 4-quinolones by means of a quasi-MS/MS/MS technique involving in-source collision-induced dissociation. It is shown that LC/quasi-MS/MS/MS can significantly enhance structural information and, thus, the specificity of analysis for the investigated 4-quinolones.

4-Quinolones↗

Effects of photoperiod history on immune responses to intermediate day lengths in Siberian hamsters (Phodopus sungorus).

Seasonal changes in day length enhance or suppress immune function in individuals of several mammalian species. Siberian hamsters (Phodopus sungorus) are long-day breeders that adjust reproductive physiology and behavior, body mass, and immune function following exposure to short photoperiods. Photoperiods of intermediate-duration, encountered in nature by juvenile hamsters born in early-spring and by those born in mid-summer, trigger gonadal development in the former cohort and inhibit the onset of puberty in the latter. Divergent reproductive responses to the same intermediate photoperiod depend on a photoperiod history, communicated during gestation. These experiments assessed whether photoperiod history during gestation likewise impacts immunological responses to intermediate photoperiods. Male hamsters were gestated in long photoperiods and remained in long photoperiods postnatally, or were transferred to an intermediate-duration or a short-duration photoperiod; other males were gestated in short days and transferred to an intermediate-duration photoperiod at birth. Long days stimulated, and short days inhibited, somatic and reproductive development; intermediate day lengths either accelerated or inhibited somatic and reproductive development, depending on whether hamsters were gestated in short days or long days, respectively. By contrast, photoperiod during gestation did not affect most immune endpoints. The data suggest that photoperiodic mechanisms that enhance and suppress several aspects of immunity in young-adult hamsters are not responsive to prenatally communicated photoperiod history information.

Age Factors↗

Episodic neurological dysfunction due to mass hysteria.

We describe 10 students from a small rural secondary school with episodes resembling seizures or syncopal attacks. Several students were initially treated for epilepsy or syncope, but the temporal pattern of the attacks, the simultaneous resolution of the episodes during a school holiday, and the fact that 4 students subsequently had pseudoseizures confirmed by video-electroencephalography strongly suggest mass hysteria. Seven students were treated with antiepileptic medications, and most underwent multiple diagnostic studies. Prompt recognition of mass hysteria allows physicians to avoid unnecessary tests and treatments and to reassure those affected as well as the general public.

Adolescent↗

Mass hysteria among schoolchildren. Early loss as a predisposing factor.

On May 21, 1979, an outbreak of illness spread swiftly among elementary school students in a Boston suburb. Of 224 boys and girls attending an assembly, 34 were hospitalized with severe dizziness, weakness, hyperventilation, headache, nausea, and abdominal pain. Sudden remission of symptoms, preponderance in girls, and failure of an extensive epidemiological investigation to detect an organic cause indicated mass hysteria. To test the hypothesis that previous loss influenced a child's vulnerability to current loss and predisposed that child to mass hysteria, we compared the incidence of family disruption in the hospitalized children with that in the nonhospitalized children. A significantly higher rate of parental divorce (P less than .00005) and death within the family (P less than .0005) occurred among the hospitalized children. These findings suggest a relationship between childhood loss and susceptibility to mass hysteria.

Adolescent↗

Electrospray ionization and collision-induced dissociation of antibiotic polyether ionophores.

A series of polyether ionophores (lasalocid, monensin-A, narasin-A and salinomycin) was investigated by electrospray ionization (ESI) tandem mass spectrometry (MS/MS). A fast short-column liquid chromatographic (LC) method, using a ternary gradient sequence, was developed to separate the ionophores in less than 4 minutes. Several mobile phase parameters such as pH and solvent additives were investigated, and their impact on both chromatographic and mass spectrometric behavior was studied. The ionophores readily formed stable complexes with various metal cations present as impurities in the solvents. Therefore, a method was developed to convert the ionophores into only sodium adduct species prior to ESI analysis. This procedure maximized both sensitivity and specificity in the subsequent MS/MS step. Low energy collision-induced dissociation (CID) of the sodium adduct ions resulted in a number of structure-diagnostic product ions for all ionophores. The proposed interpretation of these fragment ions is presented in this work. Additionally, the fragmentation of a series of monovalent carboxylic alkali-metal ion complexes of lasalocid was investigated under CID conditions. A comparison of the CID spectra revealed a decreasing degree of fragmentation in the order [M + H]+ approximately [M + NH4]+ > [M + Li]+ > [M-H + 2Li]+ > [M + Na]+ >> [M + Cs]+. To demonstrate the analytical potential of the LC/MS/MS method, its application to the determination of salinomycin in catfood samples was investigated. Salinomycin was recovered from catfood by a microwave solvent extraction procedure, and subsequently analyzed using LC/MS/MS of the sodium adduct ions.

Anti-Bacterial Agents↗

Sometimes sensitive, seldom specific: a review of the economics of screening.

As the policy relevance of screening has increased, the application of the techniques of economic evaluation to screening has become widespread. This paper critically reviews the literature, and in so doing, highlights several ways in which future evaluations might be improved. These include: the adoption of a broader perspective regarding the questions to be addressed and the relevant margins; a reconsideration of the nature of the benefits and how they might be valued; and a greater emphasis being placed upon the role of individual behaviour and its potential impact on the outcome of economic evaluations.

Cost-Benefit Analysis↗

Dimensional behavior of curing bone cement masses.

The curing of bone cements is accompanied by release of polymerization heat and, hence, by a temperature rise of the curing cement mass. This temperature rise causes expansion of enclosed air bubbles and evaporation of the volatile monomer. An overall expansion of 3 to 5 vol % has been mentioned in the literature. It has often been stated that this expansion favours the fixation of metal endoprostheses in the marrow cavity of bone. To check for the influence of this expansion on linear dimensions of the cured cement mass we filled stainless steel cylinders with a precision bore of 22,000 +/- 0,005 mm and a length of 120 mm with bone cement. After curing of the cement in a environment of 37 degrees C the resulting cement rod was released from the cylinder and the diameter of the rod was measured at 37 degrees C. The influence of the "foaming effect" on the transverse dimensions of the rods was studied by curing the cement at 37 degrees C and 2 atm air pressure in a high-pressure-vessel. This method of curing eliminates porosity in the cement almost completely, so that curing shrinkage is to be expected rather than expansion of the cement mass. The results indicate that a volumetric expansion of the cement during curing of cylindrical rods in laboratory experiments, can be accompanied by a linear diametrical shrinkage of the cement mass. The explanation of this phenomenon is to be sought in the fact that the volumetric expansion takes place at a time when the cement is still plastic; by the formation of gas bubbles, the cement is forced in longitudinal direction into the cylinder and when the temperature of the mass has passed through a maximum, the cooling of the cement mass results in a thermal shrinkage of approximately 0.4% linearly. Extrapolating this laboratory result to clinical situation one might doubt whether the overall expansion of bone cements during curing will result in a permanent positive pressure on the walls of marrow cavity and whether it will contribute to a better fixation of endoprostheses than in the case of a, still hypothetical, nonporous cement.

Bone Cements↗