A study of examiner accuracy in cartridge case comparisons. Part 2: Examiner use of the AFTE range of conclusions.

This report describes an analysis of how examiners used the Association of Firearm and Toolmark Examiners (AFTE) Range of Conclusions in a controlled study undertaken to estimate examiner error rates in comparing cartridge cases. Results of the error rate analysis are reported in [1]; this paper focuses on a broader analysis of how the entire collection of classification categories, especially those in the Inconclusive range, were used by the participating examiners. Volunteer active examiners with AFTE membership or working in laboratories that participate in Association of Crime Laboratory Directors (ASCLD) were provided with 15 sets of three known and one questioned cartridge cases fired from a collection of 25 new Ruger SR9 handguns.

Higher Levels of Protein Palmitoylation in the Frontal Cortex across Aging Were Associated with Reference Memory and Executive Function Declines.

Cognitive decline with aging is often due to altered levels of protein expression. The NMDA receptor (NMDAR) and the complex of proteins surrounding the receptor are susceptible to age-related changes in expression. In the frontal cortex of aged mice, there is a significant loss of expression of the GluN2B subunit of the NMDAR, an increase in Fyn expression, and no change in PSD-95.

Higher levels of phosphorylated Y1472 on GluN2B subunits in the frontal cortex of aged mice are associated with good spatial reference memory, but not cognitive flexibility.

The N-methyl-D-aspartate receptor (NMDAr) is particularly vulnerable to aging. The GluN2B subunit of the NMDAr, compared to other NMDAr subunits, suffers the greatest losses of expression in the aging brain, especially in the frontal cortex. While expression levels of GluN2B mRNA and protein in the aged brain are well documented, there has been little investigation into age-related posttranslational modifications of the subunit.

Xanthohumol improved cognitive flexibility in young mice.

The protein palmitoylation cycle has been shown to be important for protein signaling and synaptic plasticity. Data from our lab showed a change in the palmitoylation status of certain proteins with age. A greater percentage of the NMDA receptor subunits GluN2A and GluN2B, along with Fyn and PSD95 proteins, were palmitoylated in the old mice.

An increase in the association of GluN2B containing NMDA receptors with membrane scaffolding proteins was related to memory declines during aging.

The NMDA receptor is an important component of spatial working and reference memory. The receptor is a heterotetramer composed of a family of related subunits. The GluN2B subunit of the NMDA receptor appears to be essential for some forms of memory and is particularly vulnerable to change with age in both the hippocampus and cerebral cortex.

Reducing expression of GluN1(0XX) subunit splice variants of the NMDA receptor interferes with spatial reference memory.

The GluN1 subunit of the N-methyl-D-aspartate (NMDA) receptor shows age-related changes in its expression pattern, some of which correlate with spatial memory performance in mice. Aged C57BL/6 mice show an age-related increase in mRNA expression of GluN1 subunit splice variants that lack the N terminal splice cassette, GluN1(0XX) (GluN1-a). This increase in expression is associated with good performance in reference and working memory tasks.

Transplantation of BDNF-secreting mesenchymal stem cells provides neuroprotection in chronically hypertensive rat eyes.

Purpose: To evaluate the ability of mesenchymal stem cells (MSCs) engineered to produce and secrete brain-derived neurotrophic factor (BDNF) to protect retinal function and structure after intravitreal transplantation in a rat model of chronic ocular hypertension (COH).

Methods: COH was induced by laser cauterization of trabecular meshwork and episcleral veins in rat eyes. COH eyes received an intravitreal transplant of MSCs engineered to express BDNF and green fluorescent protein (BDNF-MSCs) or just GFP (GFP-MSCs).

The effect of firearm muzzle gases on the backspatter of blood.

Injuries caused by gunshots can produce what bloodstain pattern analysts know as "backspatter." Observations about the presence or absence of backspatter on an individual may be used in court as evidence of guilt or innocence. The discharge of three firearms (.

Limits of detection for an AOTF-FFP spectrometer in ICP atomic emission spectroscopy.

Limits of detection for a number of elements both in air and in argon inductively coupled plasma atomic emission spectroscopy (ICPAES) have been determined using a high-resolution interferometric spectrometer (HiRIS) that consists of an acousto-optic tunable filter, a fiber-optic Fabry-Perot interferometer, and a photon-counting PMT detector. Detection limits using the HiRIS are comparable to those determined using a 1.5 m focal-length grating spectrometer, which has resolution similar to that of the HiRIS.

Spectral and conformational analysis of deoxyadenosine adducts derived from syn- and anti-Dibenzo[a,l]pyrene diol epoxides: fluorescence studies.

Low-temperature fluorescence spectra and results of conformational studies with trans-syn-, cis-syn-, trans-anti-, and cis-anti-dibenzo[a,l]pyrene diol epoxide (DB[a,l]PDE)-derived deoxyadenosine (dA) adducts are presented and compared with those previously obtained for the stereoisomeric DB[a,l]P tetrols [Jankowiak, R., et al. (1997) Chem.

Synthesis and structure determination of the adducts formed by electrochemical oxidation of Dibenzo[a,l]pyrene in the presence of adenine.

Because the radical cations of polycyclic aromatic hydrocarbons (PAH) are involved in tumor initiation, determination of the structures of biologically formed PAH-DNA adducts is important and relies on comparison of their properties with those of synthesized adducts. One of the possible sites of adduct formation is the N-3 position of Ade, but this depurinating adduct is not obtained by one-electron oxidation of dibenzo[a,l]pyrene (DB[a,l]P) in the presence of deoxyadenosine. Therefore, we turned to electrochemical oxidation of DB[a,l]P in the presence of Ade in dimethylformamide and produced the following adducts: DB[a,l]P-10-N1Ade (47%), DB[a, l]P-10-N3Ade (5%), DB[a,l]P-10-N7Ade (2%), and DB[a,l]P-10-N(6)Ade (6%).

Spectral characterization of fluorescently labeled catechol estrogen 3,4-quinone-derived N7 guanine adducts and their identification in rat mammary gland tissue.

The oxidation of carcinogenic 4-hydroxycatechol estrogens (CE) of estrone (E1) and estradiol (E2) to catechol estrogen 3,4-quinones (CE-3,4-Q) results in electrophilic intermediates that covalently bind to DNA to form depurinating adducts [Cavalieri et al. (1997) Proc. Natl.

Structure, conformations, and repair of DNA adducts from dibenzo[a, l]pyrene: 32P-postlabeling and fluorescence studies.

The nature of stable DNA adducts derived from the very potent carcinogen dibenzo[a,l]pyrene (DB[a,l]P) in the presence of rat liver microsomes in vitro and in mouse skin in vivo has been studied using 32P-postlabeling and laser-based fluorescence techniques. Analysis of DB[a,l]P-DNA adducts via 32P-postlabeling has been obtained by comparison of the adduct patterns to those obtained from reactions of synthetic (+/-)-anti-, (+)-anti-, (-)-anti-, and (+/-)-syn-DB[a,l]P-11,12-diol 13,14-epoxide (DB[a,l]PDE) with single nucleotides and calf thymus DNA. anti-DB[a,l]PDE-dA adducts derived from the (-)-enantiomer are the major adducts formed in calf thymus DNA and in mouse skin DNA.

Application of capillary electrophoresis-fluorescence line-narrowing spectroscopy for on-line spectral characterization of closely related analytes.

Capillary electrophoresis (CE) interfaced with low-temperature (4.2 K) fluorescence line-narrowing spectroscopy (FLNS) is used for the separation and spectral characterization of closely related analytes. In this paper, the CE-FLNS system is applied to the analysis of a mixture of deuterated and protonated benzo[a]pyrene, a mixture of structurally similar benzo[a]pyrene and benzo[e]pyrene, and mixtures of dibenzo[a,l]pyrene-derived adenine DNA adducts.

Conformational studies of stereoisomeric tetrols derived from syn- and anti-dibenzo[a,l]pyrene diol epoxides.

An understanding of the conformational behavior of the stereoisomeric tetrols at the 11,12,13,14-positions of dibenzo[a,l]pyrene (DB[a,l]P) is essential for the spectroscopic identification of DNA adducts derived from the biologically highly active fjord region syn- and anti-DB[a,l]P-11,12-diol 13,14-epoxides. Conformational effects are expected to play an important role in DNA-DB[a,l]P diol epoxide reactivity, base-sequence specificity, and conformation dependent repair. The results of conformational studies on trans-anti-, cis-anti-, and cis-syn-DB[a,l]P tetrol isomers are presented and compared to the results obtained previously for trans-syn-DB[a,l]P tetrol (Carcinogenesis 17, 829-837, 1996).

Capillary electrophoresis-fluorescence line-narrowing system for on-line structural characterization of molecular analytes.

We have demonstrated, for the first time, that capillary electrophoresis (CE) can be interfaced with low-temperature fluorescence line-narrowing (FLN) spectroscopy for on-line structural characterization. Detection by laser-induced fluorescence spectroscopy, under fluorescence non-line-narrowing and line-narrowing conditions, provides three-dimensional electropherograms and FLN spectra, which lead to significantly improved overall resolution and allow for structural characterization ("fingerprinting") of molecular analytes. This novel CE-FLN system consists of a modular CE system, instrumentation for FLN spectroscopy, and a specially designed capillary cryostat (CC).

Fluorescence line narrowing spectrometric analysis of benzo[a]pyrene-DNA adducts formed by one-electron oxidation.

Fluorescence line narrowing (FLN) was demonstrated for five benzo[a]pyrene (BP)-nucleoside adducts synthesized by one-electron oxidation of BP in the presence of guanosine, deoxyguanosine, and deoxyadenosine. The standard FLN spectra were used to prove that a major depurination adduct from the binding of BP to DNA in rat liver nuclei is 7-(benzo[a]pyren-6-yl)guanine (N7Gua). The structural characterization was performed with only 20 pg of the adduct.

Enhancement of sensitivity of fluorescence line narrowing spectrometry for detection of carcinogen-DNA adducts.

Fluorescence line narrowing (FLN), is a method by which highly characteristic spectra have been obtained for a large number of polycyclic aromatic hydrocarbon (PAH)-DNA adducts and is well suited for the analysis of exposures to complex mixtures of PHA. The basic method is described and recent improvements discussed which overcome one of the major limitations of the method to its wider application to biological samples, that is its sensitivity.

Fluorescence line narrowing-nonphotochemical hole burning spectrometry: femtomole detection and high selectivity for intact DNA-PAH adducts.

A new fluorescence line narrowing (FLN) apparatus is described and evaluated through experiments on intact DNA-PAH (polycyclic aromatic hydrocarbon) and globin-PAH adducts, as well as polar PAH metabolites. A detection limit of approximately 3 modified bases in 10(8) for a DNA adduct formed with a diol-epoxide of benzo[a]pyrene (BPDE-DNA) is reported for 20 micrograms of DNA at a spectral resolution of approximately 8 cm-1. The methodology employed avoids or minimizes spectral degradation and loss of sensitivity due to photooxidation and nonphotochemical hole burning (NPHB).