Disposition of firocoxib in equine plasma after an oral loading dose and a multiple dose regimen.

The objective of this study was to determine if a single loading dose (LD), 3× the label dose of firocoxib oral paste, followed by nine maintenance doses at the current label dose achieves and maintains near steady state concentrations. Six healthy, adult mares were administered 0.3mg/kg of firocoxib on Day 0, and 0.1 mg/kg 24 h later on Day 1, and at 24 h intervals from Day 2 to Day 9, for a total of 10 doses. Blood samples were collected throughout the study. The mean firocoxib maximum plasma concentration and standard deviation was 199±97 ng/mL, 175±44 ng/mL and 183±50 ng/mL after the LD, and first and last maintenance doses, respectively. The minimum mean concentration (C(min)) increased from 100±23 ng/mL after the LD to 132±38 ng/mL at Day 7. Then, the C(min) remained constant until Day 9. The average concentration at steady state (C(avg)) was 150±45 ng/mL, which compares well to the C(avg) (130±36 ng/mL) reported after multiple daily doses at 0.1 mg/kg. The administration of the single LD allowed achievement of the average steady state drug concentrations faster than a multi-dose regimen without a loading dose. After the LD, firocoxib at 0.1 mg/kg every 24 h was able to maintain a relatively constant average drug concentration which should produce less variability in onset of action and efficacy.

Determination of firocoxib in equine plasma using high performance liquid chromatography.

A new method of analysis has been developed and validated for the determination of firocoxib, a new nonsteroidal anti-inflammatory drug (NSAID) approved for use in horses and dogs to control pain and inflammation associated with osteoarthritis. Following a liquid extraction using ethyl acetate:hexane (40:60), samples were separated by isocratic reversed-phase HPLC on a Sunfire C(18) column and quantified using UV detection at 290 nm. The mobile phase was a mixture of water with 0.025% trifluoroacetic acid and acetonitrile, with a flow-rate of 1.1 ml/min. The procedure produced a linear curve over the concentration range 5-1500 ng/ml with a lower limit of quantification of 5 ng/ml. Intra- and inter-assay variability was less than 7%. The average recovery was 98%. The method is suitable for the analysis of clinical samples from pharmacokinetic studies and can also be used for small volume sample sizes.

Structure-related clustering of gene expression fingerprints of thp-1 cells exposed to smaller polycyclic aromatic hydrocarbons.

This study was undertaken to test the hypothesis that structurally similar PAHs induce similar gene expression profiles. THP-1 cells were exposed to a series of 12 selected PAHs at 50 microM for 24 hours and gene expressions profiles were analyzed using both unsupervised and supervised methods. Clustering analysis of gene expression profiles revealed that the 12 tested chemicals were grouped into five clusters. Within each cluster, the gene expression profiles are more similar to each other than to the ones outside the cluster. One-methylanthracene and 1-methylfluorene were found to have the most similar profiles; dibenzothiophene and dibenzofuran were found to share common profiles with fluorine. As expression pattern comparisons were expanded, similarity in genomic fingerprint dropped off dramatically. Prediction analysis of microarrays (PAM) based on the clustering pattern generated 49 predictor genes that can be used for sample discrimination. Moreover, a significant analysis of Microarrays (SAM) identified 598 genes being modulated by tested chemicals with a variety of biological processes, such as cell cycle, metabolism, and protein binding and KEGG pathways being significantly (p < 0.05) affected. It is feasible to distinguish structurally different PAHs based on their genomic fingerprints, which are mechanism based.

Optimization study of the femtosecond laser-induced forward-transfer process with thin aluminum films.

The parameters for an effective laser-induced forward-transfer (LIFT) process of aluminum thin films using a femtosecond laser are studied. Deposited feature size as a function of laser fluence, donor film thickness, quality of focus, and the pulse duration are varied, providing a metric of the most desirable conditions for femtosecond LIFT with thin aluminum films.

Identification of reactive toxicants: structure-activity relationships for amides.

A diverse series of amides were evaluated for aquatic toxicity (IGC(50)) assessed in the Tetrahymena pyriformis population growth impairment assay and for reactivity (EC(50)) with the model soft nucleophile thiol in the form of the cysteine residue of the tripeptide glutathione. All alkylamides along with some halo-substituted amides are well predicted by the simple hydrophobicity (log K (ow))-electrophilicity (E (lumo)) response-surface model [log(IGC(-1) (50)) = 0.45(log K (ow)) - 0.342(E (lumo)) - 1.11]. However, 2-halo amides with the halogen at the end of the molecule and alpha,beta-unsaturated primary amides are among those derivatives identified as being more toxic than predicted by the model. Amides, which exhibit excess toxicity, were capable of forming covalent bonds through an S(N)2 displacement or a Michael addition. Moreover, only those amides exhibiting excess toxicity were reactive with thiol, suggesting that the reactivity with model nucleophiles such as the thiol group may provide a means of accurately defining reactive toxicants.

Toxicity to Tetrahymena and abiotic thiol reactivity of aromatic isothiocyanates.

Toxicity (1/IGC(50)) in the Tetrahymena population growth assay and reactivity (1/EC(50)) with the thiol moiety of the cysteine residue of glutathione (GSH) were determined for a series of aromatic isothiocyanates (NCSs). Comparison of both toxicity and reactivity between the analogues revealed that derivatives with the NCS-moiety attached directly to an aromatic ring (e.g., phenyl derivatives) are less toxic and less reactive than those with the NCS attached to an aliphatic carbon (e.g., benzyl derivatives). These differences in potency are hypothesized to relate to difference in the ease of the Michael reaction, the proposed molecular mechanism. 1,4-Phenylene diisothiocyanate is more toxic and more reactive than its mono-NCS homologue. While there is good predictivity for the phenyl and naphthyl derivatives with the model log(1/IGC(50)) = 0.545(log K(ow)) + 16.21A(max) - 5.91, based on the 1-octanol/water partition coefficient (K(ow)) and maximum acceptor superdelocalizability (A(max)), toxicity of the other derivatives, which are outside the structural domain of the model training set, are poorly fitted. Owing to hydrolysis, the benzoyl, and cinnamyl analogues are less toxic than predicted by their thiol reactivity; however, the toxicity of the remaining compounds is modeled by the relationship log(1/IGC(50)) = 1.77 [log (1/EC(50))] + 0.60; n = 12, s = 0.34, r(2) = 0.718, q(2) = 0.629, F = 26.

Structure-activity relationships for reactivity of carbonyl-containing compounds with glutathione.

For toxicological-based structure-activity relationships to advance, will require a better understanding of molecular reactivity. A rapid and inexpensive spectrophotometric assay for determining the reactive to glutathione (GSH) was developed and used to determine GSH reactivity (reactGSH) data for 21 aliphatic derivatives of esters, ketones and aldehydes. From these data, a series of structure-activity relationships were evaluated. The structure feature associated with reactGSH was an acetylenic or olefinic moiety conjugated to a carbonyl group (i.e. polarized alpha,beta-unsaturation). This structure conveys the capacity to undergo a covalent interaction with the thiol group of cysteine (i.e. Michael- addition). Quantitatively reactGSH of the alpha,beta-unsaturated carbonyl compounds is reliant upon the specific molecular structure with several tendencies observed. Specifically, it was noted that for alpha,beta-unsaturated carbonyl compounds: (1) the acetylenic-substituted derivatives were more reactive than the corresponding olefinic-substituted ones; (2) terminal vinyl-substituted derivatives was more reactive than the internal vinylene-substituted ones; (3) methyl substitution on the vinyl carbon atoms diminishes reactivity and methyl-substitution on the carbon atom farthest from the carbonyl group causes a larger reduction; (4) derivatives with carbon-carbon double bond on the end of the molecule (i.e. vinyl ketone) were more reactive than one with the carbon-oxygen bond at the end of the molecule (i.e. aldehyde) and (5) the ester with an additional unsaturated vinyl groups were more reactive than the derivative having an unsaturated ethyl group.

Trends in structure-toxicity relationships for carbonyl-containing alpha,beta-unsaturated compounds.

Using toxicity data for 30 aliphatic polarized alpha,beta-unsaturated derivatives of esters, aldehydes, and ketones, a series of six structure-toxicity relationships were evaluated. The structure feature of all assessed compounds, an acetylenic or olefinic moiety conjugated to a carbonyl group, is inherently electrophilic and conveys the capacity to exhibit enhanced toxicity. However, the toxic potency of alpha,beta-unsaturated carbonyl compounds is dependent on the specific molecular structure with several trends being observed. Specific observations include: (1) between homologues, the acetylenic-substituted derivative was more toxic than the corresponding olefinic-substituted one, respectively; (2) between olefinic-homologues, terminal vinyl-substituted derivative was more toxic than the internal vinylene-substituted one; (3) within alpha,beta-unsaturated ketones, methyl substitution on the vinyl carbon atoms reduces toxicity with methyl-substitution on the carbon atom farthest from the carbonyl group exhibiting the greater inhibition; (4) between alpha,beta-unsaturated carbonyl compounds with the carbon-carbon double bond on the end of the molecule (vinyl ketones) and those with carbon-oxygen double bonds on the end of the molecule (aldehydes), the ketones are more toxic than the aldehydes; (5) between homologues of alpha,beta-unsaturated esters, those with additional unsaturated moieties (allyl, propargyl, or vinyl groups) were more toxic than homologues having relevant unsaturated moieties (propyl or ethyl groups); (6) between alpha,beta-unsaturated carbonyl compounds with different shaped alkyl-groups (i.e. different degrees of branching), homologues with straight-chain hydrocarbon moieties were more toxic than those with branched groups.

Compilation and evaluation of a Paso del Norte emission inventory.

Emission inventories of ozone precursors are routinely used as input to comprehensive photochemical air quality models. Photochemical model performance and the development of effective control strategies rely on the accuracy and representativeness of an underlying emission inventory. This paper describes the tasks undertaken to compile and evaluate an ozone precursor emission inventory for the El Paso/Ciudad Juárez/Southern Doña Ana region. Point, area and mobile source emission data were obtained from local government agencies and were spatially and temporally allocated to a gridded domain using region-specific demographic and land-cover information. The inventory was then processed using the US Environmental Protection Agency (EPA) recommended Emissions Preprocessor System 2.0 (UAM-EPS 2.0) which generates emissions files compatible with the Urban Airshed Model (UAM). A top down evaluation of the emission inventory was performed to examine how well the inventory represented ambient pollutant compositions. The top-down evaluation methodology employed in this study compares emission inventory ratios of non-methane hydrocarbon (NMHC)/nitrogen oxide (NOx) and carbon monoxide (CO)/NOx ratios to corresponding ambient ratios. Detailed NMHC species comparisons were made in order to investigate the relative composition of individual hydrocarbon species in the emission inventory and in the ambient data. The emission inventory compiled during this effort has since been used to model ozone in the Paso del Norte airshed (Emery et al., CAMx modeling of ozone and carbon monoxide in the Paso del Norte airshed. In: Proc of Ninety-Third Annual Meeting of Air & Waste Management Association, 18-22 June 2000, Air & Waste Management Association, Pittsburgh, PA, 2000).

The 1996 Paso del Norte Ozone Study: analysis of meteorological and air quality data that influence local ozone concentrations.

The 1996 Paso del Norte Ozone Study and subsequent data analyses were implemented to develop an understanding of the chemical and physical processes which lead to high concentrations of ozone in the Paso del Norte study area which includes El Paso County, Texas, Sunland Park, New Mexico, and Ciudad Juárez, Mexico. Both the data and data analysis results are being used to support photochemical grid modeling. El Paso County and Sunland Park fail to meet the National Ambient Air Quality Standard (NAAQS) for ozone, and neighboring Ciudad Juárez fails to meet the Mexican ambient standard for ozone. This paper summarizes the measurement campaigns of the 1996 Paso del Norte Ozone Study and the findings and conclusions that arose from subsequent data analyses. Data analyses showed that high ozone concentrations resulted from a combination of conditions, including high surface temperatures, strong sunlight with few clouds, light surface winds and high concentrations of ozone precursors at ground level in the morning, and slow convective boundary layer (CBL) growth. Synoptic-scale meteorological conditions observed during high ozone episodes included an aloft high-pressure system and aloft warming. Aloft carryover of ozone and ozone precursors did not significantly contribute to high concentrations of ozone at the surface.

Inhibitors of intracellular chloride regulation induce cisplatin resistance in canine osteosarcoma cells.

The objective of this study was to examine the role of ion transport mechanisms in clinical anticancer drug resistance. Reduction in intracellular accumulation of cisplatin is believed to be an early change in cisplatin-resistant cells, and may be dependent on the concentration of intracellular chloride (Cl-) ions and intracellular pH. The primary aim of this study was to describe the modifying effects of NHMA (5-N,N hexamethylene; amiloride), a Na+/H+ antiport inhibitor, and/or SITS (4-acetamido-4';isothiocyanostilbene-2,2'-disulfonic acid), a HCO3-/Cl- transport inhibitor, in bicarbonate-containing or bicarbonate-free media on cisplatin (cis-diamminedichloroplatinum(II); CDDP) toxicity between known cisplatin-sensitive (COS31) and cisplatin-resistant (COS31/rCDDP) canine osteosarcoma cells. This study has shown that cell survival can be influenced by the inhibition of the Na(+)-dependent HCO3-/Cl- exchanger using SITS. The addition of SITS increases the intracellular Cl- concentration in canine osteosarcoma cells cultured in a bicarbonate-containing media. In a bicarbonate-free media, the addition of SITS results in a decrease in the cytotoxic action of cisplatin.

Suicide by cop.

STUDY OBJECTIVE: "Suicide by cop" is a term used by law enforcement officers to describe an incident in which a suicidal individual intentionally engages in life-threatening and criminal behavior with a lethal weapon or what appears to be a lethal weapon toward law enforcement officers or civilians to specifically provoke officers to shoot the suicidal individual in self-defense or to protect civilians. The objective of this study was to investigate the phenomenon that some individuals attempt or commit suicide by intentionally provoking law enforcement officers to shoot them. METHODS: We reviewed all files of officer-involved shootings investigated by the Los Angeles County Sheriff's Department from 1987 to 1997. Cases met the following criteria: (1) evidence of the individual's suicidal intent, (2) evidence they specifically wanted officers to shoot them, (3) evidence they possessed a lethal weapon or what appeared to be a lethal weapon, and (4) evidence they intentionally escalated the encounter and provoked officers to shoot them. RESULTS: Suicide by cop accounted for 11% (n=46) of all officer-involved shootings and 13% of all officer-involved justifiable homicides. Ages of suicidal individuals ranged from 18 to 54 years; 98% were male. Forty-eight percent of weapons possessed by suicidal individuals were firearms, 17% replica firearms. The median time from arrival of officers at the scene to the time of the shooting was 15 minutes with 70% of shootings occurring within 30 minutes of arrival of officers. Thirty-nine percent of cases involved domestic violence. Fifty-four percent of suicidal individuals sustained fatal gunshot wounds. All deaths were classified by the coroner as homicides, as opposed to suicides. CONCLUSION: Suicide by cop is an actual form of suicide. The most appropriate term for this phenomenon is law enforcement-forced-assisted suicide. Law enforcement agencies may be able to develop strategies for early recognition and handling of law enforcement-forced-assisted suicide (suicide by cop). Health care providers involved in the evaluation of potentially suicidal individuals and in the resuscitation of officer-involved shootings should be aware of law enforcement-forced-assisted suicide as a form of suicide.

Imaging of cell/substrate contacts on polymers by total internal reflection fluorescence microscopy.

A simplified model of total internal reflection fluorescence (TIRF) emission of fluorescently labeled cell membranes [Reichert, W. M.; Truskey, G. A. J. Cell Sci. 1990, 96, 219-230] was used to determine the topography of the cell membrane in apposition to a polymer-coated surface. The homopolymer substrates were spun cast films of hydrophilic poly(hydroxyethyl methacrylate) (polyHEMA) or hydrophobic poly(ethyl methacrylate) (polyEMA). Bovine aortic endothelial cells (BAEC) on preadsorbed fibronectin polymer substrates were either plated for 24 h, fixed, labeled, and examined by TIRF microscopy (TIRFM) and phase-contrast microscopy or plated for 2 h and tested for their adhesion strength in a parallel-plate flow chamber. BAEC attached to polyHEMA showed no evidence of focal contact formation. However, BAEC attached to polyEMA were well spread and showed an array of focal contacts. TIRFM data were transformed to construct a detailed topographical map of relative cell/substrate separation distances. Virtually all of the BAEC plated to polyHEMA were sheared from the surface when subjected to a 50 dyn/cm2 burst of laminar flow, whereas only 10% of the BAEC were sheared from the polyEMA surface. These data suggest that the polyHEMA and polyEMA surface properties (e.g., hydrophobicity) correlate with the presence of BAEC focal contacts and the BAEC attachment strength.