PCP Concentration Research Articles

Phencyclidine in Drivers and Decedents in Dallas County: A Five-Year Retrospective Review of Toxicological and Demographical Data.

Presented are phencyclidine (PCP)-positive cases received by the Toxicology Laboratory at the Southwestern Institute of Forensic Sciences from local law enforcement agencies and the Office of the Medical Examiner (OME) between 1 January 2015 and 31 December 2020. Of the 43,940 requests for testing received during that time, 898 (2.04%) were positive for PCP. These cases were evaluated for PCP concentration, additional/concurrently reported drug concentrations and demographics. For ME cases, the cause and manner of death were also evaluated. Although the number of requests received by the Toxicology Laboratory increased each year, the percentage positive for PCP remained consistent. Subjects ranged from 18 to 71 years old (median 48 years) and were predominantly black (94.19%) and male (78.49%). PCP concentrations for all case types ranged from 0.02 to 2.33 mg/L (median 0.05 mg/L); driving while intoxicated (DWI) cases ranged from 0.02 to 0.14 mg/L (median 0.04 mg/L) and ME cases ranged from 0.02 to 2.33 mg/L (median 0.13 mg/L). In addition to PCP, one or more drug(s) or metabolite(s) was identified concurrently in 69.49% of cases. Cannabinoids were the most frequently detected (39.8%), followed by cocaine and its metabolites (22.0%) and ethanol (18.5%). Results were similar when comparing the additional drugs reported in ME and DWI cases. PCP concentrations in ME samples were generally higher, especially for stimulant drugs. Of the 264 ME cases positive for PCP, the manner of death was determined to be an accident for the majority of cases (62.54%), and the most common cause of death was drug toxicity (35.61%). The results from this study facilitate comparison of laboratory- or region-specific data sets, help determine whether laboratory scopes meet testing needs, contribute to reference ranges and provide the foundation for well-informed policy decisions.

Resistance and Application of the Biomass from Fusarium solani in the Removal of Pentachlorophenol in Aqueous Solution

Recently, the removal and degradation capacity of different environmental contaminants such as heavy metals, organic solvents, oils, plastics, pesticides and herbicides, from sites contaminated by low-cost materials has been studied, with promising results. These adsorbents include agricultural and industrial waste, clay minerals, live and dead microorganismos, and others materials. The objective of this investigation was study the tolerance and removal capacity of pentachlorophenol by the environmental polluting fungus Fusarium solani, by UV-visible spectrophotometry method. The fungal strain grew on LMM supplemented with 80 mg/L of PCP about 6% of growth relative to control (118 mg of dry weight without of pesticide) was obtained. The highest adsorption was obtained at pH 5.0, at 28oC after 24 hours of incubation with 1 g of fungal biomass, and 100 rpm. If we increase the PCP concentration, the removal capacity decrease, and if the biomass concentration is increase, the removal is most efficient, and the laccase activity is increase in presence of 10 mg/L of PCP, with a degradation of 63% at 15 days of incubation.

Association of Pentachlorophenol with Fetal Risk of Prolonged Bradycardia: A Systematic Review and Meta-Analysis.

Objective This study explored the systematic evaluation and meta-analysis of different concentrations of PCP on the risk of long-term bradycardia in fetuses. Methods Cochrane Library, Embase, PubMed, China Biomedical Literature Service, CNCNKI, and Wanfang database were computerized to collect all case-control studies on the association between variety classes and different concentrations of environmental pollutant gas to fetal of prolonged bradycardia. After evaluating the quality of the inclusion study and extracting valid data, meta-analysis was performed using Stata15 software. Relative hazards were calculated using the Mantel-Haenszel method and the random effect model, and P values and I2 values were used for heterogeneity evaluation. When heterogeneity occurs, subgroup analysis and sensitivity analysis were used to explore the sources. Results A total of 15 studies were included, including 1202 patients with fetal of prolonged bradycardia and 1380 in the control population. Meta-analysis showed that there was no statistical difference in PCP < 0.1 mg/L between the experimental group and control group (OR = 1.03, 95% CI (0.62, 1.72), P=0.90, I2 = 0%, Z = 0.13), but there was a statistical difference in PCP > 5 mg/L (OR = 1.73, 95% CI (1.15, 2.58), P=0.008, I2 = 0%, Z = 2.65), PCP > 10 mg/L (OR = 1.75, 95% CI (1.19, 2.57), P=0.004, I2 = 14%, Z = 2.85), and PCP >15 mg/L (OR = 2.02, 95% CI (1.38, 2.95), P=0.0003, I2 = 77%, Z = 3.61). Conclusion In this study, we found that different concentrations of PCP increased the risk of long-term bradycardia in fetuses, and the risk coefficient increased with the increase of PCP concentration.

Anaerobic/aerobic cycle effect on di(2-ethylhexyl) phthalate and pentachlorophenol removal from real textile wastewater in sequencing batch biofilm reactor

This study aims to investigate the treatability of pentachlorophenol encountered in cotton textile plants and di(2-ethylhexyl) phthalate used in synthetic textile production. They were selected as model micropollutants. Experiments were carried out at different anaerobic/aerobic (A/O) sequences (4 h/16 h, 8 h/12 h, 12 h/8 h, 16 h/4 h) at constant hydraulic retention time (36 h) and solid retention time (15 d) to determine the effect of biocarriers addition and anaerobic/aerobic cycle time on micropollutant removal from real textile wastewater. During the study period, sequencing batch reactor and sequencing batch biofilm reactor, which contains K3 Kaldnes bio-carrier with 50% filling ratio, were fed with a real textile wastewater. Reactors were operated with a total cycle period of 24 h (fill: 0.5 h; react: 20 h; settle: 2 h; decant: 1 h; idle: 0.5 h). Their performances were compared in terms of PCP, DEHP and macro pollutants (BOD5, COD, TOC, TN, TP, and color) removals. The average DEHP and PCP concentrations in feed wastewater were 124.5 ± 5.24 and 12.8 ± 0.27 μg/L, respectively. The maximum DEHP removal efficiencies were 72.2% for SBBR at 4 h/16 h (A/O) and 42.1% for SBR at 8 h/12 h (A/O) sequence. The PCP removal efficiency was not affected significantly by the change of aeration times and remained 51.1%–56.5% for SBBR and 35.0%–43.2% for SBR. The addition of biocarrier caused 30.0% and 13.0% increase in removal efficiency for DEHP and PCP, respectively.

Toxicological and Demographic Profiles of Phencyclidine-Impaired Driving Cases in Houston.

Phencyclidine (PCP) was first synthesized in 1926 and originally developed in 1950s as a general anesthetic agent. Abuse of PCP declined at the national level since its first illicit use in 1960s, but it continues in certain areas including Houston. This research evaluates PCP-positive cases of driving while intoxicated (DWI) in 2013-2018. The blood samples were collected from drivers, submitted by the Houston Police Department and analyzed for alcohol and drugs. Toxicological findings and demographic information were evaluated for the impaired driving cases tested positive for PCP in blood. Additionally, the Drug Recognition Expert (DRE) findings were examined for 12 cases in 2018. A total of 615 DWI cases positive for PCP in blood were identified in which the traffic offense occurred between August 2013 and December 2018. The mean (median, range) PCP concentration was 47 (43, 7-180)ng/mL. A total of 23% of those cases were females, and 77% were males; 85% were blacks, 10% were whites and 5% were other races/ethnicities as identified by the arresting officer. The mean age was 37years. No significant differences in median and distribution of PCP concentrations (P's>0.05) were observed across the offense years and among demographic cohorts. A total of 43% of the cases were positive for PCP only. Among the remaining 57%, cannabinoids are the most common concurrently detected analytes (35%), followed by cocaine/metabolite (14%) and ethanol (13%). The proportion of black male PCP-positive drivers decreased in younger age groups. Common indications observed by DRE officers included slurred speech, chemical breath odor, watery and/or bloodshot eyes, vertical/horizontal gaze nystagmus and impaired coordination/balance. This study provides valuable regional information to better understand the demographic patterns of PCP-impaired drivers in Houston, TX over 6years. The findings may aid in designing and implementing regulations and prevention programs to reduce PCP-impaired driving.

Bioremediation of PCP by Trichoderma and Cunninghamella Strains Isolated from Sawdust

Four fungal isolates, SD12, SD14, SD19 and SD20 isolated from the aged sawdust grew on agar plates supplemented with PCP up to a concentration of 100 mg L-1. At high PCP concentration, isolate SD12 showed the highest radial growth rate of 10 mm day-1, followed by SD14 and SD19 both with 4.5 mm day-1 and SD20 with 4.2 mm day-1. Ultrastructural study on the effect of PCP on the PCP tolerant fungi using scanning electron microscope showed that high concentration of PCP caused the collapse of both fungal hyphae and spores. Among the four PCP tolerant fungi examined, isolate SD12 showed the least structural damage at high PCP concentration of 100 mg L-1. This fungal isolate was further characterized and identified as Cunninghamella sp. UMAS SD12. Preliminary PCP biodegradation trial performed in liquid minimal medium supplemented with 20 mg L-1 of PCP using Cunninghamella sp. UMAS SD12 showed that the degradation up to 51.7% of PCP in 15 days under static growth condition.

Factors determining the accumulation of pentachlorophenol — a precursor of dioxins in bottom sediments of the Gulf of Gdańsk (Baltic Sea)

Abstract Pentachlorophenol (PCP) and its derivatives are considered to be the precursors of dioxins, thus their concentrations in environmental compartments remain relatively correlated. Unlimited production and usage of PCP in recent decades may have posed a potential ecological threat to marine ecosystems due to uncontrolled discharge of this contaminant into the Vistula River and finally into the Gulf of Gdańsk. Since there are no data on PCP concentration in sediments of the southern part of the Baltic Sea, the level of contamination has been examined and possible influence of sediment properties in the Gulf of Gdańsk on the accumulation intensification has been investigated. The study has resulted in the evaluation of an efficient analytical procedure characterized by a low detection limit (LOD&lt;1 ng g−1 d.w.). Instrumental analyses have been supplemented with Microtox® bioassay in order to assess the sediment toxicity. The obtained concentrations in collected samples varied from below the LOD in sandy sediments to 179.31 ng g−1 d.w. in silty sediments, exceeding the PNEC value of 25 ng g−1 d.w. (Predicted No Effect Concentration) estimated for the Baltic Sea (Muir &amp; Eduljee 1999). It has been proven that properties of sediments from the Gulf of Gdańsk, including pH, Eh of bottom water, the content of water and organic matter, affect the rate of PCP accumulation. High toxicity has been recorded in the bottom sediments of the Gdańsk Deep but no statistically significant correlation between PCP concentration and the sediment toxicity has been observed. Analysis of PCP concentration distribution in sediment cores revealed that the surface layer is the most polluted one, which indicates a continuous inflow of PCP from the Vistula River. Horizontal PCP distribution in the sediment from the Gdańsk Deep reveals variability similar to that observed for highly chlorinated dioxins (Niemirycz &amp; Jankowska 2011).

Attic dust assessment near a wood treatment plant: Past air pollution and potential exposure

The wood treatment process uses substances that generate hazardous compounds that may contaminate environmental compartments. In the present study, an area under influence of a deactivated wood treatment plant was investigated to evaluate past air pollution and to try to understand local air dispersion. Attic dust samples were collected from eight residences around the plant and from two residences outside this area, as reference samples. The presence of copper, chromium, arsenic, pentachlorophenol, sixteen priority polycyclic aromatic hydrocarbons and mutagenic activity using Salmonella/microsome assay was evaluated. The residences close to the entrance to the plant were the most affected, according to potentially toxic elements analysis. The PCP concentration was 0.49mg/kg and the total PAHs content ranged from 0.40 to 13.31μg/g with greater dispersion than potentially toxic elements. The highest mutagenesis values were 15,905 and 10,399 revertants/g of dust in the absence and presence of S9 mix (mammalian metabolic activation), respectively. Samples in which the total PAHs concentration was less than 2μg/g no mutagenic effects were observed, including the residences in the reference area. The contribution of PAHs to mutagenesis was 10 percent, indicating that other compounds may contribute to the mutagenic effect. These results suggest that the population was or is potentially exposed to substances with strong effects on health.

Increased impulsive choice for saccharin during PCP withdrawal in female monkeys: influence of menstrual cycle phase.

In previous studies with male and female rhesus monkeys, withdrawal of access to oral phencyclidine (PCP) self-administration reduced responding for food under a high fixed-ratio (FR) schedule more in males than females, and with a delay discounting (DD) task with saccharin (SACC) as the reinforcer impulsive choice for SACC increased during PCP withdrawal more in males than females. The goal of the present study was to examine the effect of PCP (0.25 or 0.5mg/ml) withdrawal on impulsive choice for SACC in females during the follicular and luteal phases of the menstrual cycle. In component 1, PCP and water were available from two drinking spouts for 1.5h sessions under concurrent FR 16 schedules. In component 2, a SACC solution was available for 45min under a DD schedule. Monkeys had a choice of one immediate SACC delivery (0.6ml) or six delayed SACC deliveries, and the delay was increased by 1s after a response on the delayed lever and decreased by 1s after a response on the immediate lever. There was then a 10-day water substitution phase, or PCP withdrawal, that occurred during the mid-follicular phase (days7-11) or the late luteal phase (days24-28) of the menstrual cycle. Access to PCP and concurrent water was then restored, and the PCP withdrawal procedure was repeated over several follicular and luteal menstrual phases. PCP deliveries were higher during the luteal (vs follicular) phase. Impulsive choice was greater during the luteal (vs follicular) phase during withdrawal of the higher PCP concentration. PCP withdrawal was associated with elevated impulsive choice for SACC, especially in the luteal (vs follicular) phase of the menstrual cycle in female monkeys.

High performance composite membranes with a polycarbophil calcium transition layer for pervaporation dehydration of ethanol

A new kind of composite membranes, consisting of a polyacrylonitrile (PAN) support layer, a polycarbophil calcium (PCP) transition layer and a glutaraldehyde cross-linked chitosan (CS) active layer, was prepared by sequential casting and spin coating methods. A dense region was formed between the active layer and the transition layer as confirmed by positron annihilation spectroscopy. No distinct boundary between these two layers was observed by field emission scanning electron microscope and the total thickness of these two layers was around 200nm. The static water contact angle revealed that the PCP layer promoted interfacial compatibility between the PAN layer and the CS layer. T-peel test verified that the interfacial adhesion strength of the composite membrane was enhanced by the incorporation of PCP transition layer. The composite membranes were utilized for pervaporation dehydration of ethanol. Even when the PCP concentration was only 0.05wt%, the CS/PCP/PAN membrane exhibited a high performance with the separation factor of 1279 and the permeation flux of 1390g/m2h for 90wt% ethanol aqueous solution at 353K with a flow rate of 60L/h and a pressure of 0.1kPa at the downstream side of the membrane. Furthermore, the composite membrane displayed desirable stability during the long-term continuous operation.

The ozone mass transfer characteristics and ozonation of pentachlorophenol in a novel microchannel reactor

A “T” junction microchannel was employed to investigate the ozone mass transfer characteristics without chemical reaction taking place in the solution firstly. The correlations of the experimental kLα values with dimensionless numbers: ShL, Ret, ReL, Sc for Taylor, slug–annular and churn flow regimes were proposed through a least square regression method. The gas–liquid interfacial area was determined by chemical adsorption method in the present work. The results indicated that the effect of superficial liquid velocity on the interfacial area was insignificant compared with that of superficial gas velocity. And on the basis of the interfacial area determined above, the liquid side ozone mass transfer coefficient under varied superficial gas and liquid velocities was calculated. The mass transfer rate was accelerated in the presence of PCP in solution. The reaction rate between PCP and O3 was proved to fell in the instantaneous regime based on the experimental results of EO3 increasing with either liquid PCP concentration or the reciprocal interfacial ozone concentration, (CO3,L,i)−1. In addition, further studies indicated that dissociation of PCP and the elevation of the average mass transfer driving forces caused by increasing pH and gaseous ozone concentration, respectively, availed the degradation of PCP in the microchannel.

Isolation and process parameter optimization of Brevibacterium casei for simultaneous bioremediation of hexavalent chromium and pentachlorophenol

Chromate and pentachlorophenol are major pollutants discharged through tanneries. Three bacteria resistant to high Cr(6+) and PCP concentrations simultaneously were isolated. The TVS-3 strain was tolerant to highest 850 mg l(-1) Cr(6+) and 1000 mg l(-1) PCP concentration and concomitantly reduced 69% Cr(6+) and degraded 72% PCP within 168 h at pH 7.5, 35 ± 1°C temperature, was selected and identified as Brevibacterium casei. At 168 h of growth, bacterium showed maximum PCP utilization of 720 mg l(-1) and released 900 mg l(-1) chloride ion. The bacterium exhibited remarkable ability to significantly reduce Cr(6+) and degrade PCP in presence of other metals, between 100-120 rpm aeration and over broad pH (6.5-10.0) and temperature (30-40°C) range. Maximum 78% Cr(6+) reduction and 82% PCP degradation was observed at pH 8.0, 35 ± 1°C within 168 h of incubation, 120 rpm and initial concentration of 850 mg l(-1) Cr(6+) and 1000 mg l(-1) PCP. This is the first study reporting 78% Cr(6+) reduction and 82% PCP degradation simultaneously by single native bacteria under wide growth conditions utilizing PCP as sole carbon source. This bacterium may potentially be useful for simultaneous bioremediation of Cr(6+) and PCP containing wastes in the environment.

Predictors of PCP, OH-PCBs, PCBs and chlorinated pesticides in a general female Norwegian population

The aims of the current study were to assess plasma concentrations and predictors of halogenated phenolic compounds (HPCs), polychlorinated biphenyls (PCBs) and chlorinated pesticides in a representative group of postmenopausal Norwegian women (n=311, mean age: 56years). In addition to delivering a blood sample, the participants had also filled out a detailed questionnaire regarding their current health status, use of medication and dietary habits, etc. The association between a large number of dietary variables, lifestyle factors and plasma concentration of organic pollutants were investigated using multivariate statistics.Within the current study group, p,p′-DDE (median: 903ng/L w.w.) and pentachlorophenol (PCP, median: 711ng/L w.w.) were the dominating compounds on a wet weight basis and were present in considerable higher concentrations than the PCBs, the hydroxylated PCBs (OH-PCBs) and the remaining chlorinated pesticides. Of the PCBs, PCB 153 was detected in highest concentrations, whereas 4-OH-PCB187 was present in highest concentration of the selected OH-PCBs. The ratio of ΣOH-PCB to ΣPCB varied between 0.06 and 0.77ng/L and were significantly lower in individuals with higher ΣPCB concentration. PCP did not co-vary with the other contaminants, indicating a different route of exposure. No clear food cluster was positively associated with PCP exposure; however intake of marine food was negatively linked to PCP concentration and age and being a non-smoker were positive predictors of PCP. The other investigated contaminants co-varied and were positively associated with age, plasma concentrations of marine derived omega-3 fatty acids and a traditional Norwegian fish and bread based diet. The difference in contaminant concentration between high, medium and low consumers of total marine food were however marginal for the dominating PCBs and chlorinated pesticides. The current results indicate however that marine food in itself could be a source of some of the OH-PCBs, regardless of their PCB precursors.As PCP is one of the dominating organic contaminants within the general female Norwegian population, future research on human concentrations, exposure routes and potential health effects of PCP is encouraged. Continued monitoring of human OH-PCB levels should also be performed as they could be present at levels almost as high as the PCBs and they are expected to be more toxic than their mother substances.

Mineralization of pentachlorophenol with enhanced degradation and power generation from air cathode microbial fuel cells

The combined anaerobic-aerobic conditions in air-cathode single-chamber MFCs were used to completely mineralize pentachlorophenol (PCP; 5 mg/L), in the presence of acetate or glucose. Degradation rates of 0.140 ± 0.011 mg/L-h (acetate) and 0.117 ± 0.009 mg/L-h (glucose) were obtained with maximum power densities of 7.7 ± 1.1 W/m(3) (264 ± 39 W/m(2), acetate) and 5.1 ± 0.1 W/m(3) (175 ± 5 W/m(2), glucose). At a higher PCP concentration of 15 mg/L, PCP degradation rates increased to 0.171 ± 0.01 mg/L-h (acetate) and 0.159 ± 0.011 mg/L-h (glucose). However, power was inversely proportional to initial PCP concentration, with decreases of 0.255 W/mg PCP (acetate) and 0.184 W/mg PCP (glucose). High pH (9.0, acetate; 8.0, glucose) was beneficial to exoelectrogenic activities and power generation, whereas an acidic pH = 5.0 decreased power but increased PCP degradation rates (0.195 ± 0.002 mg/L-h, acetate; 0.173 ± 0.005 mg/L-h, glucose). Increasing temperature from 22 to 35°C enhanced power production by 37% (glucose) to 70% (acetate), and PCP degradation rates (0.188 ± 0.01 mg/L-h, acetate; 0.172 ± 0.009 mg/L-h, glucose). Dominant exoelectrogens of Pseudomonas (acetate) and Klebsiella (glucose) were identified in the biofilms. These results demonstrate that PCP degradation using air-cathode single-chamber MFCs may be a promising process for remediation of water contaminated with PCP as well as for power generation.

Evaluation of a New Phencyclidine Enzyme Immunoassay for the Detection of Phencyclidine in Urine with Confirmation by High-Performance Liquid Chromatography-Tandem Mass Spectrometry

We present an evaluation of a new phencyclidine (PCP) enzyme immunoassay (PCPI) for detection in urine. The PCPI was evaluated by testing 523 urine specimens. Controls containing 0 ng/mL of PCP and -25% (negative control) and +25% (positive control) of the 25 ng/mL cutoff calibrator were analyzed with each batch. All urines were analyzed by high-performance liquid chromatography- tandem mass spectrometry (HPLC-MS-MS) for PCP. Of the 523 specimens tested, 218 yielded positive results by the PCP assay. HPLC-MS-MS confirmed the presence of at least 25 ng/mL in 214 specimens, indicating four false-positive results containing 11, 13, 16, and 20 ng/mL PCP. Three specimens yielded a negative result; however, PCP concentrations were within 20% of the 25 ng/mL cutoff value. The overall agreement of PCPI and HPLC-MS-MS results was 98.7%. The sensitivity of the PCPI was 0.982 and the specificity 0.987. Testing at 100 ng/mL of other drugs or their metabolites demonstrated no cross-reactivity. The within-run precision was CV = 2% (n = 12); the between-run precision was CV = < 6% (n = 4). The assay was found linear from -50% to 150% (12.5-37.5 ng/mL) of the cutoff concentration. The Lin-Zhi PCPI provides a precise, reliable method for the routine detection of phencyclidine in urine specimens.

Inhibition of G Protein-Activated Inwardly Rectifying K+ Channels by Phencyclidine

Addictive drugs, such as opioids, ethanol, cocaine, amphetamine, and phencyclidine (PCP), affect many functions of the nervous system and peripheral organs, resulting in severe health problems. G protein-activated inwardly rectifying K+ (GIRK, Kir3) channels play an important role in regulating neuronal excitability through activation of various Gi/o protein-coupled receptors including opioid and CB1 cannabinoid receptors. Furthermore, the channels are directly activated by ethanol and inhibited by cocaine at toxic levels, but not affected by methylphenidate, methamphetamine, and 3,4-methylenedioxymethamphetamine (MDMA) at toxic levels. The primary pharmacological action of PCP is blockade of N-methyl-D-aspartate (NMDA) receptor channels that are associated with its psychotomimetic effects. PCP also interacts with several receptors and channels at relatively high concentrations. However, the molecular mechanisms underlying the various effects of PCP remain to be clarified. Here, we investigated the effects of PCP on GIRK channels using the Xenopus oocyte expression system. PCP weakly but significantly inhibited GIRK channels at micromolar concentrations, but not Kir1.1 and Kir2.1 channels. The PCP concentrations effective in inhibiting GIRK channels overlap clinically relevant brain concentrations in severe intoxication. The results suggest that partial inhibition of GIRK channels by PCP may contribute to some of the toxic effects after overdose.

Phencyclidine: A 5-Year Retrospective Review from the New York City Medical Examiner’s Office

We report here a 5-year retrospective review of autopsy cases from the New York City Medical Examiner's Office that demonstrated phencyclidine (PCP) in the blood. There were a total of 138 cases. There were 52 deaths because of mixed drug intoxication: the blood PCP concentrations in these cases ranged from <1 to 598 ng/mL. There were 80 violent deaths in which PCP was quantified in the blood but was unrelated to the cause of death. There were five nonviolent deaths in which PCP exclusively was detected. In four of these, there were preexisting medical conditions that could also have contributed to death. In these, the highest PCP concentration was 361.3 ng/mL, a concentration lower than seven of the individuals in our violent death category. This suggests that lower concentrations may be fatal with comorbid conditions.

Effects of altering reinforcer magnitude and reinforcement schedule on phencyclidine (PCP) self-administration in monkeys using an adjusting delay task

Compared to nondrug reinforcers, few studies have examined delay discounting for drug reinforcers. The purpose of the present study was to examine delay discounting in rhesus monkeys using orally delivered phencyclidine (PCP) as the reinforcer and to examine the effects of manipulating reinforcer magnitude and cost on delay discounting for PCP using an adjusting delay task. Monkeys could choose between a single delivery of PCP available immediately or a bundle of PCP deliveries available following a titrated delay. The average of the delays, or the mean adjusted delay (MAD), served as the quantitative measure of delay discounting. In Experiment 1, reinforcer magnitude was manipulated by varying the PCP concentration and the size of the delayed reinforcer (6 or 12 deliveries). The concentration-effect curve for PCP deliveries assumed an inverted U-shaped function, but varying PCP concentration had little effect on MAD values or the choice between immediate and delayed reinforcers. Increasing the size of the delayed reinforcer produced an upward and leftward shift in the concentration-effect curve. In Experiment 2, the cost of reinforcers was manipulated by increasing the fixed ratio (FR) requirement for each choice. Increasing the FR led to increased MAD values and decreased PCP self-administration.

Phencyclidine and cannabinoids in vitreous humor

Vitreous humor (VH) is routinely collected at autopsy for the testing of electrolytes and ethanol. In recent years drugs of abuse have been detected in this specimen. In this study the authors assayed 30 VH samples for phencyclidine (PCP) and 50 specimens for cannabinoids. Specimens were screened by immunoassay and then assayed for PCP by GC-FID and cannabinoids by GC/MS. Eighteen (60%) specimens screened positive for PCP using a cutoff of 25 ng/mL. Quantitative analysis showed PCP concentrations in VH that screened positive ranged 30–290 ng/mL. Corresponding blood concentrations were 50–600 ng/mL. VH PCP concentrations in the 12 cases which screened negative were 40–470 ng/mL. False negative results were probably due to matrix effects. All VH specimens screened for cannabinoids were negative. Ten negative screening specimens assayed by GC/MS yielded 1 11-nor-9-carboxy-delta-9-tetrahydrocannabinol positive result at 2 ng/mL. These data indicated that VH maybe a useful specimen for the detection of PCP but not for cannabinoids.

Effects of Sublethal Concentrations of Portland Cement Powder in Solution on the Aminotransferases of the African Catfish (Clarias Gariepinus (Burchell, 1822))

The present study investigated the effect of sublethal concentrations of Portland cement powder in solution (PCPS) (39.10, 19.55, 9.87 and 0.00 mg/L) on the aminotransferases (Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST)) of the African catfish (Clarias gariepinus) with the aim to ascertain which of the selected organs (liver or kidney) or serum was mostly affected by the toxicant after a 15-day exposure period. The effect of sublethal concentrations of PCPS on the aminotransferases of Clarias gariepinus was significantly different (p < 0.01). The decrease in the activity of the aminotransferases was inversely proportional to the concentration of PCPS. The most significant decrease in the activity of AST was observed in liver, less significant in serum and the least in kidney, whereas the activity of ALT most significantly decreased in kidney, less in liver and the least in serum. Thus, PCP concentrations in the range of 9.87–39.10 mg/L in the aquatic ecosystem were harmful to the j...