W.J. Nooyen

Stable and sensitive method for the simultaneous determination of N5-methyltetrahydrofolate, leucovorin, methotrexate and 7-hydroxymethotrexate in biological fluids

A high-performance liquid chromatographic method for the determination of N5-methyltetrahydrofolic acid, leucovorin, methotrexate and 7-hydroxymethotrexate in plasma and liquor samples is presented. Gradient elution is used to increase the sensitivity. Four sample preparation methods were compared with respect to the stability of the injectable sample. Samples can be pretreated with a simple deproteinization method. For enhanced selectivity a solid-phase extraction procedure is described.

Cerebrospinal fluid tumour markers in patients treated for meningeal malignancy.

The results of cerebrospinal fluid (CSF) biochemical markers were compared with conventional CSF cytology in patients treated for leptomeningeal metastases from extra cranial malignancies. For lumbar CSF, before treatment, no statistically significant difference of the probabilities of being positive was found between CSF cytology and a classification by linear discriminant analysis, based on patients age, of beta-glucuronidase and beta 2-microglobulin. During treatment, classification by linear discriminant analysis was found more often positive than cytology. Possible mechanisms for this difference are discussed. For ventricular CSF a correlation was found between CSF cytology and beta-glucuronidase for solid tumours, and between CSF cytology and beta 2-microglobulin for haematological malignancies. Reference values for ventricular protein, CEA beta-glucuronidase and beta 2-microglobulin were obtained for cytological negative samples.

Serial lumbar and ventricular cerebrospinal fluid biochemical marker measurements in patients with leptomeningeal metastases from solid and hematological tumors

SummaryThis study presents results of investigations of lumbar and ventricular cerebrospinal fluid (CSF) biochemical markers (Beta-glucuronidase (B-gluc), Beta-2-microglobulin (B2-m), and carcinoembrionic antigen (CEA)) in 28 patients with five different tumor types with leptomeningeal metastasis diagnosed by CSF cytology and/or autopsy. All received methotrexate and radiotherapy at some stage. Decadron or other symptomatic treatments were not used.Measurements of the concentrations of B-gluc, B2-m and CEA were evaluated with the aim of correlating the results of these measurements to site of disease, of monitoring response and early relapse of leptomeningeal disease, and of establishing the duration of survival. than those obtained from lumbar CSRThe markers did not correlate with site of disease or CSF cytology. A clear relationship was found between pretreatment lumbar CSF B2-m and CEA levels, response to therapy and survival. The markers are also useful for monitoring response. The findings of this study indicate that B2-m and CEA levels have a prognostic value with regard to response to therapy and time of survival.

Analytical methods for the determination of vinca alkaloids in biological specimens: A survey of the literature

The bio-analysis and pharmacokinetics of vinca alkaloids have been the subject of many investigations. In most cases radiolabelled compounds have been used for quantification purposes. Although this method lacks selectivity, it has provided valuable information on tissue distribution of unchanged drug and metabolites in an early stage of clinical and preclinical investigations. During the last few years, methods based on high-performance liquid chromatography have been presented. This paper reviews the methods described in the literature for the bio-analysis of vinca alkaloids, supplemented with our own experience in this field. Special attention is paid to the problems that may arise during the analytical processes.

Cerebrospinal fluid beta2-microglobulin: a study in controls and patients with metastatic and non-metastatic neurological diseases

We studied cerebrospinal fluid Beta 2-microglobulin (CSF B2-m) in 197 patients with a variety of neurological diseases to evaluate the usefulness of B2-m in the detection of meningeal dissemination of malignancy. In the control group we found a relationship between CSF log B2-m and age (P less than 10(-4)). Age standardized reference values were established as 0.65-2.2 mg/l. The results show that CSF B2-m was elevated in leptomeningeal metastases from solid and haematological tumors. We observed slight elevations of CSF B2-m in epidural and parenchyma metastases from solid tumors. Our study shows that B2-m in CSF is a sensitive marker for meningeal metastases especially from hemopoietic tumors.

Bio-analysis of vinorelbine by high-performance liquid chromatography with fluorescence detection.

A simple and selective procedure for the determination of vinorelbine, a new semi-synthetic vinca alkaloid, is presented. The method is based on ion-exchange high-performance liquid chromatography on normal-phase silica with fluorescence detection, combined with liquid-liquid extraction using diethyl ether for sample clean-up. The absence of endogenous interferences and the excellent chromatographic behaviour of vinca alkaloids provides accurate results even at low concentrations. The limit of determination in plasma is 1.5 micrograms/l (500-microliters sample). Reproducible recoveries in urine were obtained if 10-50 microliters of sample were processed supplemented with 500 microliters of blank plasma.

Sensitivity and specificity of single and combined tumour markers in the diagnosis of leptomeningeal metastasis from breast cancer.

The clinical efficacy of four laboratory tests in detecting leptomeningeal metastases in 57 patients with breast carcinoma was assessed. The sensitivity and specificity of beta-glucuronidase, beta 2-microglobulin, carcinoembryonic antigen and lactate dehydrogenase in cerebrospinal fluid were determined. As a single test beta-glucuronidase was the most sensitive (93%) and specific (93%) for discriminating between leptomeningeal metastases and other CNS metastases from breast cancer. Lactate dehydrogenase was the next most useful marker. Both beta 2-microglobulin and carcinoembryonic antigen had a sensitivity of 60%. More specific results were achieved by combining beta-glucuronidase and lactate dehydrogenase. CSF beta-glucuronidase may be useful by itself and in combination with lactate dehydrogenase in the detection of leptomeningeal metastases from breast carcinoma.

High-performance liquid chromatographic determination of vinblastine, 4-O-deacetylvinblastine and the potential metabolise 4-O-deacetylvinblastine-3-oic acid in biological fluids

Procedures for the determination of vinblastine (VBL), 4-O-deacetylvinblastine (DVBL) and 4-O-deacetylvinblastine-3-oic acid (DVBLA) in biological samples using high-performance liquid chromatography (HPLC) combined with selective sample clean-up are presented. VBL and DVBL were determined in plasma and urine using ion-exchange normal-phase HPLC with fluorescence detection. The limit of detection was 1 microgram/l for both compounds using a 500-microliter sample. Successful chromatographic analyses of DVBLA were achieved by using a glass column packed with 5-microns Hypersil ODS and acetonitrile-0.05 M phosphate buffer (pH 2.7) (23:77, v/v). Positive identification was supported by the use of diode-array detection. The limit of detection (at 270 nm) was 10 micrograms/l using 1-ml samples.

High-performance liquid chromatographic bio-analysis and preliminary pharmacokinetics of the experimental antitumour drug vintriptol

A high-performance liquid chromatographic procedure, including sample pretreatment, is presented for the analysis of the experimental antitumour drug vintriptol in plasma. The sample pretreatment involved liquid-liquid extraction of the buffered (pH 3) sample with chloroform. Vinblastine was used as internal standard. Separation was achieved on a Hypersil ODS (5 microns) column with a mobile phase of acetonitrile-phosphate buffer. Electrochemical detection (at +0.70 V) was used, giving a detection limit of 2 micrograms/l. The applicability of the assay was demonstrated in a pharmacokinetic study with eight cancer patients who received 45 or 50 mg/m2 vintriptol in a phase I study. A three-compartment model was used to fit the plasma concentration-time curves. Pharmacokinetic parameters are presented.

Tumour markers in the cerebrospinal fluid of patients with central nervous system metastases from extracranial malignancies

We have assessed the diagnostic value of the determination of cerebrospinal fluid lactate dehydrogenase, carcinoembryonic antigen, beta 2-microglobulin, beta-glucuronidase and total protein, using linear discriminant analysis, in detecting central nervous system metastases from extracranial malignancies. We conclude that, using these tests, it is impossible to differentiate between control individuals and patients with brain or epidural metastases. Leptomeningeal dissemination from either solid tumours or non-Hodgkin lymphoma could be differentiated from control individuals and patients with brain or epidural metastases. In this differentiation it is essential that bacterial, fungal or tuberculous meningitis be excluded from the differential diagnosis by other diagnostic procedures. The combination of beta-glucuronidase and beta 2-microglobulin provides almost the same diagnostic information as the combination of all parameters.