Biomedical subjects

J A Tomlinson

Publications and source records attributed to J A Tomlinson.

14 recordsLinked to original sources

PubMed2005

On-site DNA extraction and real-time PCR for detection of Phytophthora ramorum in the field.

Phytophthora ramorum is a recently described pathogen causing oak mortality (sudden oak death) in forests in coastal areas of California and southern Oregon and dieback and leaf blight in a range of tree, shrub, and herbaceous species in the United States and Europe. Due to the threat posed by this organism, stringent quarantine regulations are in place, which restrict the movement of a number of hosts. Fast and accurate diagnostic tests are required in order to characterize the distribution of P. ramorum, prevent its introduction into pathogen-free areas, and minimize its spread within affected areas. However, sending samples to a laboratory for testing can cause a substantial delay between sampling and diagnosis. A rapid and simple DNA extraction method was developed for use at the point of sampling and used to extract DNAs from symptomatic foliage and stems in the field. A sensitive and specific single-round real-time PCR (TaqMan) assay for P. ramorum was performed using a portable real-time PCR platform (Cepheid SmartCycler II), and a cost-effective method for stabilizing PCR reagents was developed to allow their storage and transportation at room temperature. To our knowledge, this is the first description of a method for DNA extraction and molecular testing for a plant pathogen carried out entirely in the field, independent of any laboratory facilities.

DNA↗

PubMed2001

Increasing bioanalytical throughput using pcSFC-MS/MS: 10 minutes per 96-well plate.

The utility of packed-column supercritical, subcritical, and enhanced fluidity liquid chromatographies (pcSFC) for high-throughput applications has increased during the past few years. In contrast to traditional reversed-phase liquid chromatography, the addition of a volatile component to the mobile phase, such as CO2, produces a lower mobile-phase viscosity. This allows the use of higher flow rates which can translate into faster analysis times. In addition, the resulting mobile phase is considerably more volatile than the aqueous-based mobile phases that are typically used with LC-MS, allowing the entire effluent to be directed into the MS interface. High-throughput bioanalytical quantitation using pcSFC-MS/MS for pharmacokinetics applications is demonstrated in this report using dextromethorphan as a model compound. Plasma samples were prepared by automated liquid/liquid extraction in the 96-well format prior to pcSFC-MS/MS analysis. Three days of validation data are provided along with study sample data from a patient dosed with commercially available Vicks 44. Using pcSFC and MS/MS, dextromethorphan was quantified in 96-well plates at a rate of approximately 10 min/plate with average intraday accuracy of 9% or better. Daily relative standard deviations (RSDs) were less than 10% for the 2.21 and 14.8 ng/mL quality control (QC) samples, while the RSDs were less than 15% at the 0.554 ng/mL QC level.

Antitussive Agents↗

PubMed2001

Supermarket tampering: cocaine detected in syringes and in fruit.

Product tampering, as detailed by the Federal Anti-Tampering Act of 1983 (1), is a felony punishable by both fine and imprisonment. The rationale for product tampering ranges from pranks and attention seeking acts to extortion, terrorism, and homicide. One such case submitted for analysis involved four medical syringes found in a supermarket and suspected of being used to tamper with various products. One of the syringes was found piercing a pear while the other three syringes were found with needles exposed in other parts of the supermarket. Microscopic analysis was used to collect residue from the syringe barrels and the pear. A multidiscipline approach involving SLM, PLM, including microchemical analysis, FTIR, and GC/MS analyses, performed on the residual liquid found in the syringe barrels and in the suspect pear, confirmed the presence of cocaine. This multidisciplinary approach is often necessary when there is a possible health risk to the public and rapid response is important. With this approach, it was quickly determined which drugs or poisons were used in this tampering.

Cocaine↗

PubMed1997

Detection of clenbuterol in bovine retinal tissue by high-performance liquid chromatography with electrochemical detection.

A method for the detection of the beta-agonist drug clenbuterol in bovine retinal tissue has been developed. The extraction procedure involves sonication and centrifugation, followed by the addition of ethylenediaminetetraacetic acid (EDTA) to the supernatant. The pH of the supernatant is then brought to 12.2, which is then allowed to sit for 2 h. This is followed by a diethylether extraction. The diethylether extract is dried under nitrogen and the residue is dissolved in 1% formic acid. The quantitation of clenbuterol was accomplished by high-performance liquid chromatography with electrochemical detection. The electrochemical detector was an amperometric detection. The detector was set in the pulsed mode. The oxidizing potential of a carbon electrode was 1.3 V vs. a Ag/AgCl reference electrode and was pulsed to a reduction potential of 2.0 V vs. a Ag/AgCl reference electrode. The limit of detection for this method was 5 ng/ml of clenbuterol (S/N = 3). Typical spiked recoveries are 75%.

Adrenergic beta-Agonists↗

PubMed1993

Malignant fibrous histiocytoma developing in burn scar of the ear.

Malignant fibrous histiocytoma is the most common soft tissue sarcoma. The tumours usually present as a painless enlarging mass deep to the subcutaneous tissue most often in the thigh. Wide excision is the recommended treatment, as the incidence of recurrence is high in patients with marginal excision. Metastases can occur in 50 per cent of patients. This patient represents a rare and previously unreported presentation of malignant fibrous histiocytoma in a burn scar of the ear.

Aged↗

PubMed1982