Leukapheresis for the extraction of monocytes and various lymphocyte subpopulations from peripheral blood: product quality and prediction of the yield using different harvest procedures.

BACKGROUND AND OBJECTIVES: Leukapheresis of non-mobilized healthy donors is performed to harvest monocytes and lymphocyte subpopulations for use in various therapeutic regimens. In this methodological study, we compared two different leukapheresis programs, using equivalent volumes of processed blood over similar processing periods, to determine the influence of the procedures on the donor peripheral blood count and to establish the procedure that yields the highest quality product. MATERIALS AND METHODS: The target variables obtained in 41 healthy blood donors who underwent short-term leukapheresis (80-105 min) were retrospectively compared. Twenty-one volunteers were processed on a COBE Spectra machine at the MNC setting and 20 volunteers were processed at the AutoPBSC setting. Data were collected on pre- and postleukapheresis samples and on the product. RESULTS: AutoPBSC and MNC procedures resulted in a decrease of haemoglobin (5-7%), platelets (17-20%), monocytes (22%) and lymphocytes (23-27%), but not of granulocytes in peripheral blood. Both procedures produced nearly identical leucocyte and lymphocyte yields. AutoPBSC products contained a greater number of granulocytes, monocytes and red cells, but fewer platelets. The preleukapheresis values correlated with the yields for monocytes, T-helper and T-suppressor cells, B-lymphocytes and natural killer cells, but not for granulocytes or platelets. CONCLUSIONS: Leukapheresis is a safe and efficient procedure for collecting large numbers of peripheral blood monocytes and different lymphocyte populations from non-mobilized donors. The two programs yield comparable leucocyte harvests. Based on our results, yields can be predicted from the peripheral cell counts.

Rapid gas chromatographic procedure for the determination of topiramate in serum.

A rapid gas chromatographic method for the routine determination in serum of the new anticonvulsant drug topiramate (Topamax) (TOP) is described. The method involves extracting 0.50 mL of sample, previously adjusted to pH 9.5 with saturated borate buffer with ethyl acetate. One-microliter aliquots of the extract were injected into a 10-m x 0.53-mm i.d. x 0.5-microm 100% methyl silicone megabore capillary column connected to a nitrogen-phosphorus detector. The column temperature was initially at 170 degrees C for 0.1 min, then programmed at 10 degrees C/min to 240 degrees C, then 20 degrees C/min to 280 degrees C for 0.5 min. Under these conditions of the assay, the retention times of TOP and mepivicaine, internal standard, were 4.0 and 3.4 min, respectively. Quantitative determinations were performed with peak-height ratios of TOP to the internal standard. Calibration curves were linear from 2.5 to 150 mg/L TOP. The assay had a limit of quantitation of 2.5 mg/L. The overall within-run precision of the method yielded coefficients of variation (CV) of 3.9% at 10 mg/L (n = 10) and 3.1% at 100 mg/L (n = 10). The overall between-run precision calculated by three determinations on a single day for a week yielded CVs of 7.3% at 23 mg/L (n = 12) and 7.8% at 85 mg/L (n = 12). Common anticonvulsant and basic/neutral extractable drugs were found not to interfere with the assay. At present, no correlation has been demonstrated between trough plasma TOP concentrations and clinical efficacy. However, TOP values observed in our laboratory in serums from patients receiving adjunctive treatment for seizure disorders ranged from 2.5 to 35 mg/L.

Heat and pH alter the concentration of deoxynivalenol in an aqueous environment.

The effects of heat (100, 120, and 170 degrees C and pH (4.0, 7.0, and 10.0) on the stability of deoxynivalenol (DON) were measured in an aqueous buffer solution for different periods of time (15, 30, and 60 min). At pH 4.0 DON appeared to be very stable showing no destruction at 100 or 120 degrees C and only partial destruction at 170 degrees C after 60 min. At pH 7.0 DON was still stable but showed more destruction at 170 degrees C after 15 min. At pH 10.0 DON was partially destroyed at 100 degrees C after 60 min and was totally destroyed at 120 degrees C after 30 min and at 170 degrees C after 15 min.

Ethylene oxide on electrophysiology catheters following resterilization: implications for catheter reuse.

Reuse of electrophysiology catheters is an important cost-saving option for many laboratories. However, to be reused safely, catheters must undergo resterilization with ethylene oxide (EtO). Residual EtO levels on resterilized catheters may be high and could pose a risk to patients. Resterilized diagnostic electrophysiology catheters were tested for residual EtO using headspace gas chromatography after both a standard resterilization with an aeration process and after a resterilization process that incorporated a detoxification period. The Food and Drug Administration's maximum permissible level of EtO for implantable products, 25 parts per million (ppm), was used as the cutoff for acceptable catheter residuals. At day 2 after standard resterilization, the residual level of EtO on catheters was high at 41 +/- 6 ppm. However, these levels decreased with shelf time, decreasing to 26 +/- 3 ppm by day 7 and to 14 +/- 2 ppm by day 14 after sterilization, at which time all catheters were <25 ppm (p <0.001). Detoxification periods of 6, 12, and 15 hours were tested and 15 hours was found to be optimal. After 15 hours of detoxification, residual EtO was 19 +/- 1 ppm by day 2 and all catheters were <25 ppm. In summary, electrophysiology catheters that have undergone resterilization have residual EtO levels that are twice the Food and Drug Administration's limit for implantable products. Residual EtO levels may be substantially reduced either by allowing a 14-day waiting period after resterilization or by incorporating a detoxification period immediately after EtO exposure.

Gas chromatographic procedures for determination of ethanol in postmortem blood using t-butanol and methyl ethyl ketone as internal standards.

Three gas chromatographic procedures for the determination of ethanol in postmortem blood using alternative internal standards to n-propanol are presented: a direct injection procedure using t-butanol, and two headspace methods using t-butanol and methyl ethyl ketone. t-Butanol and methyl ethyl ketone were well resolved from ethanol, acetone, methanol and other commonly observed putrefactive volatiles using direct injection or headspace analysis. CVs for the direct injection method were below 5% for ethanol and below 10% for the other volatiles. The lower limits of detection (LOD) were 25-50 mg/L. The CVs for the headspace methods were below 5% for ethanol and below 6% for the other volatiles. The LODs were 10 mg/L using either t-butanol or methyl ethyl ketone as internal standards. The use of t-butanol or methyl ethyl ketone as alternatives to n-propanol avoids the possibility of error in the quantitation of ethanol due to the presence of n-propanol and allows for the identification of other volatiles that may aid in distinguishing antemortem ingestion from postmortem production of ethanol.

Determination of gabapentin in serum using solid-phase extraction and gas-liquid chromatography.

A gas-liquid chromatographic method for the determination of gabapentin (Neurontin) is described. The method involves extracting 0.5 mL of acidified sample by C18 solid-phase column, derivatization with MTBSTFA plus 1% tBDMCS, and analysis on an HP-1 column with a flame-ionization detector. Quantitation was performed with peak-height ratios of gabapentin to a gabapentin analogue [(1-aminomethyl-1-cycloheptyl) acetic acid] as the internal standard. The assay had a limit of detection of 0.2 mg/L and a linear range from 0.5 to 30.0 mg/L. Several compounds were analyzed for potential interference, and none interfered with the assay.

Improved method for quantification of the bacteriocin nisin.

Nisin, a bacteriocin produced by Lactococcus lactis subsp. lactis, is used in some types of food preservation due to its inhibitory action on Gram-positive bacteria and their spores. A commonly used agar diffusion bioassay technique for quantification of nisin in food samples was modified to increase its sensitivity, accuracy and precision. Several variables were evaluated. Results showed Micrococcus luteus as the most sensitive organism tested, a lower agar concentration (0 x 75% compared 1 x 5%) increased the sensitivity of the assay (21% improvement over standard method), and incorporation of 1% Na2HPO4 buffer into the bioassay agar made it possible to prevent false inhibitory zones from developing due to the low pH of the test solutions. This resulted in a 57% improvement in accuracy and a 12% improvement in precision compared to the standard method.

Confirmation of metastatic prostatic carcinoma to lung by immunohistochemistry.

In recent years, immunoperoxidase staining of fine needle aspirates has been proposed. This study examines the use of immunoperoxidase staining of prostatic acid phosphatase and prostatic specific antigen in two cases where differentiation of prostatic carcinoma from other carcinomas manifesting as metastatic lesions is essential. The histologic differentiation of primary and metastatic disease, which has significant therapeutic and prognostic implications, has been enhanced by the use of immunoperoxidase staining. The presented cases demonstrate the ease with which immunoperoxidase staining can be done in a community hospital.