Identification of an amiodarone metabolite in the plasma of patients receiving a single dose of the drug was carried out by mass-spectrometry following extraction and HPLC separation. The kinetics of the plasma concentrations of unchanged compound and its identified metabolite (N-monodesthyl-amiodarone) were studied in six patients after a single administration of amiodarone by oral or intravenous routes, using a sensitive and specific high-performance liquid chromatographic method. The observed plasma clearance rate for the drug varied from 0.2 to 0.5 1.h-1.kg-1 of body weight; and the elimination half-life of the unchanged compound was found to be approximately 21 hours. Oral bioavailability, as determined in one patient, was about 60%. The proportion of the metabolite found in the plasma following a single oral administration was significantly higher than that observed after infusion. The ratio of areas under the curves for metabolite-to-unchanged compound was 0.55 and 0.13 for oral and intravenous doses respectively. During a circumscribed study carried out in five patients receiving oral doses of the drug (daily dose varied from 2.6 to 9.3 mg/kg) accumulation of the metabolite was observed. The mean of the plasma level ratios (metabolite to-unaltered drug) obtained in five patients was approximately 0.97.

Aged↗

PubMedDate not supplied

Analysis of human T-lymphotrophic virus sequences in multiple sclerosis tissue.

Several observations suggest that retroviral infection is involved in the pathogenesis of the human demyelinating disease multiple sclerosis (MS). First, lymphadenopathy-associated virus/human T-lymphotropic virus type III (LAV/HTLV-III), the agent of acquired immune deficiency syndrome (AIDS), has been shown to be neurotropic in man. Second, the genetic organization of the lentivirus visna, which causes a chronic demyelinating disease of sheep, closely resembles that of LAV/HTLV-III. Recently, Koprowski and colleagues reported that MS is associated both with raised levels of circulating antibodies to HTLV-I and with the presence of HTLV-I-specific RNA within cell lines derived from the cerebrospinal fluid (CSF). Here we report that no HTLV-I-like or LAV/HTLV-III-like sequences can be detected, by in situ hybridization, in central nervous system (CNS) tissues from MS patients, and that nonspecific HTLV-I-like signal in peripheral blood mononuclear cells or in CSF cell lines is characteristic of MS. Furthermore, enzyme-linked immunosorbent assay (ELISA) analysis of circulating and CSF antibodies for HTLV-I reactivity fails to distinguish between MS and control groups.

Antibodies, Viral↗

PubMedDate not supplied

Apheresis experience with a continuous flow cell separator.

The Dideco Vivacell separator is a continuous-flow centrifugation system that has only recently been used for cytapheresis. The authors' experience with this separator in 451 plateletpheresis and 164 leukapheresis procedures is presented. Platelet collection provided high platelet yields (9.53 +/- 2.85 X 10(11) with a collection efficiency of 74 +/- 14 percent for about 6 liters of total blood processed. Functional integrity was confirmed by normal in vitro tests (aggregation and response to hypotonic stress) and good in vivo recovery (55%). In leukapheresis, white cell yields were high (3.42 +/- 1.2 X 10(10) with 85 percent polymorphonuclear neutrophil cells. Their oxidative metabolism functions (generation of free oxygen radicals), investigated by chemiluminescence, were increased over donor values. Donor reactions, all of the mild citrate type, were rare.

Blood Component Removal↗

PubMedDate not supplied

Monitoring of the intracellular activation of 5-fluorouracil to deoxyribonucleotides in HT29 human colon cell line: application to modulation of metabolism and cytotoxicity study.

An HPLC method was developed for in vitro detection and monitoring of intracellular metabolites of [3H]-5-fluorouracil (FUra). Results showed a preferential activation of FUra to ribonucleoside and ribonucleotide derivatives (FURd, FUMP, FUDP and FUTP) in the human colorectal HT29 cell line. We screened various agents so as to determine if they could act as modulators of metabolism and/or toxicity of FUra by reversing the activation pathway of FUra from ribo- to deoxyribonucleotides, thus enhancing FdUMP formation. Different drugs (efflux inhibitors, catabolism inhibitors and enzymatic cofactors) were tested for enhancement of cytotoxicity when associated with FUra. The most promising agents were further studied by assessment of their ability to modulate intracellular activation of FUra to enhance thymidylate synthase (TS) inhibition by FUra and to increase the subsequent induction of apoptosis. 2'-Deoxyinosine (d-Ino), a deoxyribose 1-phosphate donor increasing thymidine phosphorylase activity, stood out as the best modulating agent we screened. Results showed an up to 30-fold increase of cytotoxicity along with a stronger inhibition of TS when FUra was associated with d-Ino, while FUra alone exhibited a lesser effect on TS activity. Besides, HPLC analysis revealed a complete reversal of the activation pathway of FUra, thus leading to an intracellular accumulation of deoxyribonucleotides. Assessment of cell cycle distribution showed a marked increase (+480%) of apoptosis in cells exposed to FUra/d-Ino compared to FUra alone. The HPLC method we developed is a convenient tool for assessing to what extent modulators will actually act on the intracellular activation of FUra. This study confirms the potentiality of d-Ino to modulate FUra metabolism in vitro. It proved to be an agent able to orientate the mechanism of action of FUra towards the inhibition of TS in cells where the normal activation pathway of the drug does not result in the intracellular accumulation of the active metabolite FdUMP.

Cell Cycle↗

PubMedDate not supplied

New variants of B16 mouse melanoma: differentiation and metastatic properties.

A system of tumor transplantation has been developed to select metastatic variants of B16 in mutants of the C57BL/6J black strain of mice. The effects of transplantation into nonagouti a/a and mutant recipients on the production of melanin and on the metastatic potential of tumors were investigated. Transplantation of the pigmented B16 melanoma from a nonagouti black a/a host to a yellow mutant Ay/a recipient resulted in an achromic and metastatic variant melanoma, designated YB16. The amelanotic phenotype occurred consistently after more than ten passages through yellow mice and simultaneously with an increase in the incidence of pulmonary metastases. When YB16 was transplanted back to the nonagouti black a/a host, a second variant, MB16, characterized by its variable pigmentation, was obtained. Pigmented and/or entirely achromic tumors were observed. MB16 was dramatically more metastatic than B16 and YB16 when injected s.c. or i.v. Metastases in the lungs were pigmented and/or achromic. The properties of tumor cells derived from artificially induced metastases were investigated after s.c. and i.v. injections. Whereas the metastatic cells expressed a potent ability to generate metastases when injected s.c., no differences in the incidence of metastases, as compared to the metastatic potential of cells of parental origin, were observed after i.v. injection. In the MB16 variant, there appeared to be an inverse relationship between differentiation (production of melanins) and malignancy. Our results demonstrate that differentiation and metastatic behaviour are dependent on specific mutations in the host environment which generate a pool of tumor cells from which highly metastatic variants can be selected.

Animals↗

PubMedDate not supplied

[Determination of the optimal dose of bromazepam in the elderly].

The aim of our study was to determine in patients over 70 years, the optimal dose of Bromazepam. Seven patients were administered a unique dose of Bromazepam (3 mg), then repeated doses (1.5 mg) every 12 hours for 9 days. Cmax was 42.5 +/- 12 ng/ml in Tmax ranged from 2 to 12 hours after the first dose-concentrations of Bromazepam at steady-state were between 79 and 157 ng/ml. Half life was 30.5 +/- 14.7 hrs for the unique and the repeated doses. Sleeping was noted for concentrations over 40 ng/ml. The dose of 1.5 mg bid is recommended in old patients.

Administration, Oral↗

PubMedDate not supplied