Super-optimality and relative distance coding in location memory.

The prevailing model of landmark integration in location memory is Maximum Likelihood Estimation, which assumes that each landmark implies a target location distribution that is narrower for more reliable landmarks. This model assumes weighted linear combination of landmarks and predicts that, given optimal integration, the reliability with multiple landmarks is the sum of the reliabilities with the individual landmarks. Super-optimality is reliability with multiple landmarks exceeding optimal reliability given the reliability with each landmark alone; this is shown when performance exceeds predicted optimal performance, found by aggregating reliability values with single landmarks.

Direction and distance information in memory for locations of objects relative to landmarks and boundaries.

An observer often remembers an object's location on the basis of its direction and distance from reference objects. Two kinds of reference object are of particular interest: landmarks and boundaries. We compared how well observers remembered the direction and distance of target objects from a landmark and a boundary.

Greater sensitivity in separation discrimination with closer spacing of separation levels tested.

We explored the effects of spacing in the levels of separation tested in a separation discrimination task. Participants indicated, for pairs of test circles, whether the separation between them was greater than a standard separation. A critical set of equally-spaced separation levels was tested in two conditions.

Determination of Patient Adherence for Duloxetine in Urine.

Duloxetine, known by its brand name, CymbaltaTM, is a selective serotonin and norepinephrine reuptake inhibitor used to treat major depressive disorders. Determination of patient compliance for duloxetine is typically determined through medication possession ratio (MPR) or plasma concentrations. The purpose of this paper was to characterize normal urinary duloxetine concentrations in patients prescribed duloxetine to monitor patient adherence.

Ritalinic acid in urine: Impact of age and dose.

Objectives: The objective of this work was to study the results of urine drug testing for ritalinic acid (RA), the major urinary metabolite of methylphenidate (MP) (e.g., Ritalin®).

The effects of visual discomfort and chromaticity separation on neural processing during a visual task.

Visual stimuli that are uncomfortable to look at evoke a large neural response suggesting altered processing. While there is some evidence linking uncomfortable achromatic stimuli to impaired visual processing, the effect of uncomfortable chromatic patterns on visual cognition has yet to be explored. Large differences in chromaticity separation (e.

A Rapid LC-MS-MS Method for the Quantitation of Antiepileptic Drugs in Urine.

Epilepsy is a common neurologic disease that requires treatment with one or more medications. Due to the polypharmaceutical treatments, potential side effects, and drug-drug interactions associated with these medications, therapeutic drug monitoring is important. Therapeutic drug monitoring is typically performed in blood due to established clinical ranges.

A Dilute and Shoot LC-MS/MS Method for Antipsychotics in Urine.

Adherence to prescribed antipsychotics is an ongoing problem. Traditionally, estimates of adherence have been made from patient interviews, pill counting and blood testing. A number of methods for the analysis of antipsychotics in blood have been reported for both therapeutic drug monitoring and postmortem testing for toxicity.

Development and Validation of a Novel All-Inclusive LC-MS-MS Designer Drug Method.

Designer drugs including synthetic cannabinoids and synthetic cathinones are an increasing problem due to the ease of access to these compounds. They present analytical challenges inasmuch as the compound structures are numerous and growing within each class. Typically each class of designer compounds is analyzed separately due to differences in chemistry, desired cut-offs or other reasons.

Nicotine and cotinine in oral fluid: Passive exposure vs active smoking.

Scheidweiler and colleagues have clinically tested and identified a reporting cutoff (10 ng/mL) of nicotine and cotinine in oral fluid that could reliably determine active smoking in patients. The results from that study were reevaluated using a large data set of oral fluid nicotine and cotinine results available from pain medication monitoring. Additionally, test results from patients using a nicotine transdermal patch delivery device are compared with those from smokers.

Zolpidem and Zolpidem Carboxylic Acid Results from Medication Monitoring.

Zolpidem (Ambien®) is one of the "Z" drugs often used to improve sleep in older patients and those suffering from insomnia. Schwope, D.M.

Impact of β-Glucuronidase Mediated Hydrolysis on Haldol® Urinalysis.

Reports have suggested that patients with mental health disorders including major depressive disorder and schizophrenia have dramatically low adherence levels to prescribed medications. Patients on haloperidol (Haldol®) therapy, regardless of their disease, were found to have higher adherence levels-though still strikingly low. This work shows that high levels of the glucuronidated form of haloperidol are present in patient urine samples.

Analytical Considerations When Developing an LC-MS/MS Method for More than 30 Analytes.

Background: While validation of analytical (LC-MS/MS) methods has been documented in any number of articles and reference texts, the optimal design and subsequent validation of a method for over 30 analytes presents special challenges. Conventional approaches to calibration curves, controls, and run time are not tenable in such methods. This report details the practical aspects of designing and implementing such a method in accordance with College of American Pathologists validation criteria.

Patterns of Marijuana Use in a 6-Month Pain Management Sample in the United States.

This study is a 6-month retrospective analysis of urine drug testing (UDT) data from a pain management population among specimens with clinician-ordered marijuana testing (N = 194 809). Descriptive statistics about the specimen positivity of clinician-ordered marijuana UDT are provided as well as other drug positivity. Specimens from men and adults aged 18 to 34 years had the highest prevalence rates of marijuana positivity.

Quetiapine Carboxylic Acid and Quetiapine Sulfoxide Prevalence in Patient Urine.

Treatment adherence is often an issue with mental health patients. For those prescribed quetiapine (Seroquel), the low levels of parent drug and plasma metabolite(s) (e.g.

Fentanyl-Norfentanyl Concentrations During Transdermal Patch Application: LC-MS-MS Urine Analysis.

Poklis and Backer published a survey of the concentrations of fentanyl and norfentanyl that could be expected in urine from patients using Duragesic, a transdermal fentanyl patch. That study employed a relatively small number of patient data points and analysis by Gas Chromatography/Mass Spectrometry. This work examines a larger population of patient positives for fentanyl and norfentanyl to determine whether more than a decade later the original report remains accurate in predicting the range and median levels of fentanyl and norfentanyl concentrations physicians can expect to see from their patients.

Normalizing Oral Fluid Hydrocodone Data Using Calculated Blood Volume.

Oral fluid testing to assist in the assessment of treatment adherence for chronic pain patients is attractive for a number of reasons. However, efforts focused on interpreting patient results have been modest when compared to urine drug testing. This work details a retrospective approach developed to transform and normalize oral fluid testing results to provide a historical picture of patient values in this important test fluid.

Improved Chiral Separation of Methamphetamine Enantiomers Using CSP-LC-MS-MS.

To determine the true enantiomeric composition of methamphetamine urine drug testing results, chiral separation of dextro (D) and levo (L) enantiomers is necessary. While enantiomeric separation of methamphetamine has traditionally been accomplished using gas chromatography-mass spectrometry (GC-MS), chiral separation of D- and L-methamphetamine by chiral stationary phase (CSP) liquid chromatography-mass spectrometry/mass spectrometry (LC-MS-MS) has proved more reliable. Chirally selective detection of methamphetamine by GC-MS is often performed using L-N-trifluoroacetyl-prolyl chloride (TPC).

A Dilute-and-Shoot LC-MS Method for Quantitating Opioids in Oral Fluid.

Opioid testing represents a dominant share of the market in pain management clinical testing facilities. Testing of this drug class in oral fluid (OF) has begun to rise in popularity. OF analysis has traditionally required extensive clean-up protocols and sample concentration, which can be avoided.

Capillary electrophoresis-mass spectrometry determination of morphine and its isobaric glucuronide metabolites.

The determination of morphine and its isobaric metabolites morphine-3-beta-d-glucuronide (M3G) and morphine-6-beta-d-glucuronide (M6G) is useful for therapeutic drug monitoring and forensic identification of drug use. In particular, capillary electrophoresis with mass spectrometry (CE-MS) represents an attractive tool for opioid analysis. Whereas volatile background electrolytes in CE often improve electrospray ionization for coupled MS detection, such electrolytes may reduce CE separation efficiency and resolution.

Rapid enzymatic hydrolysis using a novel recombinant β-glucuronidase in benzodiazepine urinalysis.

Only trace amounts of parent benzodiazepines are present in urine following extensive metabolism and conjugation. Thus, hydrolysis of glucuronides is necessary for improved detection. Enzyme hydrolysis is preferred to retain identification specificity, but can be costly and time-consuming.