Cerebrospinal fluid (CSF) TRAP. A method to improve CSF laboratory efficiency.

Establishment of a procedure termed cerebrospinal fluid (CSF) TRAP ("Transport and Rapid Accessioning for Additional Procedures") allows clinicians to appropriately store, at -75 degrees C, and rapidly access CSF specimens. The CSF TRAP enhances patient care by decreasing the need for repeat lumbar punctures and providing reserve fluid for the following: (1) further CSF testing; (2) repeating questionable test results; and (3) laboratory accidents. The CSF TRAP has been approved for third-party payment because it promotes efficient laboratory utilization by encouraging clinicians to review initial CSF findings before ordering low-yield CSF assays such as the venereal disease research laboratory (VDRL) and cryptococcal antigen latex agglutination tests. Currently, CSF TRAP samples are being obtained with 40% of all CSF acquisitions at the Duke University Medical Center. The availability of the CSF TRAP was associated with a significant decrease in the ordering of CSF VDRL and cryptococcal antigen assays (P less than 0.05); however, there was no significant change in the proportion of those studies being performed on normal CSF. The CSF TRAP procedure provides the framework for an overall restructuring of CSF testing that is being investigated.

Establishment of a CSF bank.

A bank of well-characterized CSF has been established by collecting and storing (-70 degrees C) CSF samples remaining after completion of routine clinical studies. Over 1,700 individual patient samples were collected during a 12-month period. A database derived largely from information down-loaded from existing hospital-based systems includes the results of individual CSF laboratory studies, in addition to the patient age, primary diagnoses, and details of any malignancy. CSF control material is used to verify storage conditions. The CSF bank supplies investigators with CSF handled in a standardized manner for more precise investigation of CNS disease.

Low-dose chenodiol to prevent gallstone recurrence after dissolution therapy.

Chenodiol is a safe and effective agent for the medical dissolution of gallstones in selected patients; however, after dissolution and cessation of treatment, gallstones recur. This study was done to determine the recurrence rate after successful medical treatment and cessation of chenodiol therapy; compare the efficacy and safety of low-dose chenodiol, as compared to placebo, for prophylaxis against recurrence; and identify factors predictive of recurrence. In a randomized, double-blind fashion, 53 patients with gallstone dissolution received either chenodiol, 375 mg/d, or placebo, for at least 2 years. Standardized oral cholecystograms were done at 6 months, 1 year, and then yearly thereafter. Routine laboratory testing was done every 6 months. The cumulative rate of recurrence (life-table) was 27% in patients followed for up to 3.5 years. Chenodiol, 375 mg/d, was ineffective in preventing the recurrence of gallstones. No demographic, clinical, roentgenographic, or biochemical characteristics were predictive of recurrence.

Central laboratory quality control in the National Cooperative Gallstone Study.

This article presents the rationale, selection, operation, and quality control of the Central Serum and Central Bile Laboratories utilized by the National Cooperative Gallstone Study. The external quality control protocols were designed to monitor long-term stability of the analytical procedures and to measure the precision of the measurements as affected by the collection, labelling, storage, shipping, and laboratory methods. For both laboratories, the assessment of long-term stability by pool standards failed to produce the data necessary to come to relevant conclusions. Several of the problems involved, however, did lead to protocol changes that increased the reliability of the laboratory data. The use of duplicate measurements to monitor precision was more successful and demonstrated acceptable performance of these systems. This article describes the external quality control surveillance procedures employed in the NCGS, their strengths and weaknesses, statistical methods for the analysis of such quality control programs, and the implications for the final statistical analyses of the clinical trial patient data.

Therapeutic monitoring of tricyclic antidepressants in plasma by gas chromatography.

We describe a comprehensive gas chromatographic analysis for therapeutic concentrations of amitriptyline, nortriptyline, imipramine, desipramine, doxepin, and desmethyldoxepin in plasma, with use of a nitrogen detector. All these drugs are extracted and chromatographed under identical conditions. Each tertiary amine tricyclic is well resolved from its secondary amine metabolite on a mixed-phase column and the concentrations of both are determined simultaneously, without derivatization. The lower limit of sensitivity is 10 microgram/liter of plasma (2-ml sample). Analytical recoveries of the tertiary and secondary amines are 100 and 80%, respectively. Between-run CV's for all of the drugs ranged between 5 and 7%.