Performance evaluation of an in-injection port thermal desorption/gas chromatographic/negative ion chemical ionization mass spectrometric method for trace explosive vapor analysis

A gas chromatographic method utilizing thermal desorption of Tenax TA and sol-gel sorbent traps has been developed and validated for the analysis of trace explosive vapor with negative ion chemical ionization mass spectrometric detection. Sorbent tubes were packed with Tenax TA and sorbent particles prepared in-house by the sol-gel process. Thermal desorption was performed within a split/splitless injection port with minimal instrument modification. Performance was characterized by relative thermal desorption recovery, precision (reproducibility), linearity of the calibration, and method detection limits. Method validation was performed with a series of dinitrotoluenes, dinitrobenzene, trinitrotoluene, trinitrobenzene, two aminodinitrotoluenes, three nitroesters, and two nitramines. The performance of Tenax TA and the sol-gel sorbents is evaluated based on the method validation data. The method was applied to the analysis of trace explosive vapor collected and concentrated with sol-gel solid sorbent traps from the headspace of a smokeless gunpowder sample.     

Hemispherectomy for intractable seizures: presurgical cerebral glucose metabolism and post-surgical non-verbal communication

This study examined the presurgical 2-deoxy-2[18F]-fluoro-D-glucose positron emission tomography (PET) patterns of regional cerebral glucose metabolism in the non-resected hemisphere of 13 children who underwent hemispherectomy for early-onset intractable seizures. These patterns were compared with the rate of change in the children's non-verbal communication scores, measured before and after surgery. Irrespective of the side of surgery, the pre-operative glucose metabolism in the non-resected prefrontal cortex correlated significantly with the postoperative rate of change in the children's ability to focus the attention of an adult on an object or event (joint attention). These preliminary findings suggest that pre-operative PET patterns might be associated with certain aspects of the developmental outcome of children undergoing hemispherectomy.     

Development of new cancer chemoprevention agents: role of pharmacokinetic/pharmacodynamic and intermediate endpoint biomarker monitoring

Dimerization is a prerequisite for many growth factors in their receptor activation leading to cellular response. FGF-1 and FGF-2, members of the Fibroblast Growth Factor (FGF) family, were shown to form non-covalent dimers and oligomers in vitro. Using the two-hybrid system as an in vivo binding assay we show here that of three representative members of the FGF family, only FGF-2 is able to homodimerize. Moreover the FGF-2 isoforms could heterodimerize. Two single-point mutants (T121F and W123R), defective in their dimerization capability, were isolated through random mutagenesis and were used to study the role of FGF-2 dimerization with regard to its biological activity. Remarkably, these mutant proteins were still able to induce cell differentiation, but were strongly affected in their capacity to promote cell proliferation. This study thus highlights the uncoupling between proliferation and differentiation FGF-2 signaling pathways and the crucial role of FGF-2 dimerization in the mitogenic activity of this factor.     

Longitudinal study of sensorimotor development.

Assessed the longitudinal performance of 24 healthy full-term infants from middle-class homes using an adapted version of scales by I. Casati and I. Lezine measuring stages of sensorimotor intelligence in children. The study focused on the rate of acquisition of differing sensorimotor behaviors, variability in the performance of these behaviors, and the relationship between performance on the various subtests. Results show that although there was an overall progression in stage development for the behaviors studied, occasional declines in performance were also present. Performance on one subtest was generally unrelated to performance on another subtest. In addition, longitudinal data on the development of object permanence compared favorably with previously reported results from a cross-sectional sample. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is affect aversive to young children with autism? Behavioral and cardiac responses to experimenter distress

The aim of this study was to determine whether displays of negative emotions are more aversive to young children with autism than displays of neutral emotions. The attention, behavioral reactions, facial affect, and cardiac responses of 22 autistic and 22 mentally retarded 3-5-year-old children were compared when an experimenter pretended to hurt herself and showed strong distress in contrast to when the experimenter pretended to hurt herself but showed only neutral affect. The children in both diagnostic groups looked more at the experimenter and appeared more interested and concerned when she displayed strong distress than when she showed neutral affect. The heart rate of the mentally retarded children decreased during the distress condition relative to a baseline condition, but the heart rate of the children with autism did not change across conditions. In summary, the children with autism gave no evidence of being overly aroused by or avoiding the distressed experimenter.     

Attention regulation by children with Down syndrome: coordinated joint attention and social referencing looks

We examined attention regulation of children in two different situations designed to elicit triadic interactions (i.e., between self, other, and object). Thirty-five children with Down syndrome and 23 children with typical development were observed in a semi-structured adult-child interaction designed to elicit coordinated joint attention and an ambiguous situation in which a moving robot prompted an emotional response from the adults in order to elicit social referencing looks from the child. Children with Down syndrome engaged in significantly fewer social referencing looks. Group differences were not found for coordinated joint attention looks, suggesting that the difficulty for children with Down syndrome is in cognitive appraisal abilities.     

Equilibrium partitioning model applied to RDX-halide adduct formation in electrospray ionization mass spectrometry

An equilibrium partitioning model is applied for the first time to the sequential formation of 1:1 and then 2:1 adducts between the high explosive cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) and halide anions fluoride, chloride, bromide, and iodide in electrospray ionization interface (ESI) mass spectrometry. The equilibrium partitioning model is developed and model calculations are presented to demonstrate the generic behavior of the system, which is in qualitative agreement with the observed changes in 1:1 (RDX-halide) and 2:1 (RDX-halide) responses in ESI-MS. The model is successfully applied to the experimental data with the use of octanol-water partitioning coefficients to predict interior-to-surface partitioning behavior of the complexes in droplets formed in the ESI. The data and model suggest that the significantly more hydrophobic 2:1 complexes are readily observed in ESI-MS, even though their formation constants may be several orders of magnitude less than that of the 1:1 complex. Structures for RDX-halide 1:1 and 2:1 complexes are proposed based on ion-dipole attractions and destabilizing dipole-dipole interactions.     

Preliminary models of risk and protective factors for childhood homesickness: review and empirical synthesis

Empirical research and conventional wisdom have suggested numerous risk and protective factors for the development of homesickness. Yet no study has integrated predictors and sequelae of homesickness into a testable statistical model. As a first step in developing a pathogenic model of homesickness in children, this study measured, factor analyzed, and modeled 14 predictors and 8 sequelae of homesickness. Using a sample of 293 boys, ages 8-16, spending 2 weeks at an overnight summer camp, this study tested 2 alternate models, focusing on the roles of boys' interpersonal attitudes, perceived control, and separation expectations in the subsequent development of homesickness. Results indicated that interpersonal attitudes and perceived control may predict boys' preseparation beliefs about whether they will become homesick. This "homesick disposition" combines with little prior separation experience to account for 69% of the variance in self-reported homesickness. Homesickness was not a powerful predictor of negative emotion, whereas interpersonal attitudes and perceived control predicted 70% of the variance in negative emotion. Results are discussed in the context of contemporary theories of homesickness.     

Resistances in a hospital setting: issues in resolution

Poly(ADP-ribosyl)ation of mutant and wild-type p53 was studied in transformed and nontransformed rat cell lines constitutively expressing the temperature-sensitive p53135val. It was found that in both cell types at 37.5 degrees C, where overexpressed p53 exhibits mutant conformation and cytoplasmic localization, a considerable part of the protein was poly(ADP-ribosyl)ated. Using densitometric scanning, the molecular mass of the modified protein was estimated as 64 kD. Immunofluorescence studies with affinity purified anti-poly(ADP-ribose) transferase (pADPRT) antibodies revealed that, contrary to predictions, the active enzyme was located in the cytoplasm, while in nuclei chromatin was depleted of pADPRT. A distinct intracellular localization and action of pADPRT was found in the cell lines cultivated at 32.5 degrees C, where p53 adopts wild-type form. Despite nuclear coexistence of both proteins no significant modification of p53 was found. Since the strikingly shared compartmentalization of p53 and pADPRT was indicative of possible complex formation between the two proteins, reciprocal immunoprecipitation and immunoblotting were performed with anti-p53 and anti-pADPRT antibodies. A poly(ADP-ribosyl)ated protein of 116 kD constantly precipitated at stringent conditions was identified as the automodified enzyme. It is concluded that mutant cytoplasmic p53 is tightly complexed to pADPRT and becomes modified. At 32.5 degrees C binding to DNA of p53 or its temperature-dependent conformational alteration might prevent an analogous modification of the tumor suppressor protein.