The role of cytochrome P450 2D6 in the metabolism of moclobemide

The metabolic fate of moclobemide (Ro 11-1163), a new reversible and selective inhibitor of monoamine oxidase type A (MAO-A), has been assessed in a pilot study in 2 debrisoquine poor metabolizers (PM) and 4 extensive metabolizers (EM) after multiple oral dosings of moclobemide with and without co-medication of dextromethorphan. Absorption and disposition parameters were not different between PM and EM. Concurrent application of dextromethorphan, a selective substrate of CYP2D6, did not affect the pharmacokinetics of moclobemide. These results indicate that the cytochromal isoenzyme CYP2D6 does not play a major role in the metabolic degradation of moclobemide. Limited CYP2D6 activities because of a genetic defect or co-medications with CYP2D6 substrates should therefore not give rise to elevated moclobemide blood levels.

Automated determination of dextromethorphan and its main metabolites in human plasma by high-performance liquid chromatography and column switching

An automated column-switching technique coupled to isocratic high-performance liquid chromatography (HPLC) with fluorescence detection was developed for simultaneous determination of dextromethorphan and its three major metabolites, dextrorphan, hydroxymorphinan, and methoxymorphinan. After cleavage of conjugates by incubation with glucuronidasearylsulfatase at 37 degrees C for 15 h, plasma samples were injected directly into the HPLC system. Dextromethorphan and metabolites were retained on a cleanup column (10 x 4.6 mm internal diameter [ID]) filled with cyanopropyl (CN) material (Hypersil CPS, 10-microns article size) while interfering proteins and lipids were washed to waste. After column switching, the drugs were eluted from the cleanup column and separated on Spherisorb CN material (5-microns particle size, column size 250 x 4.6 mm ID). Fluorescence detection was carried out with an excitation wavelength of 220 nm and an emission wavelength of 305 nm. Sample cleanup and HPLC separation were completed within 20 min. Regression analyses found linearity (r > 0.99) between drug concentration and detector response over a wide range-5-220 ng/ml for dextromethorphan, 5-550 ng/ml for dextrorphan, 5-500 ng/ml for hydroxymorphinan, and 5-200 ng/ml for methoxymorphinan. The limit of quantification was approximately 5 ng/ml, and the recovery was > 90% for all compounds. At concentrations of 20-500 ng/ml, the intra- and interassay coefficients of variation ranged from 3.5 to 14.6% and from 7.0 to 14.0%, respectively. The method is suitable for in vivo phenotyping of CYP2D6 activity, which catalyzes the O-demethylation of dextromethorphan to dextrorphan, and is also applicable to pharmacokinetic studies in man.

Reactive arthritis induced by Strongyloides stercoralis

Reactive arthritis induced by Strongyloides is exceedingly rare. A case in a 53-year-old man from the Guadeloupe (French Antilles) is reported. The outcome was rapidly favorable under thiabendazole therapy. The cycle of Strongyloides is reviewed, and the contribution of parasites to reactive arthritis in patients with genetic risk factors is discussed. Establishing the correct diagnosis is sometimes difficult but is essential in order to avoid inappropriate administration of corticosteroids that can lead to fatal, multivisceral dissemination of the parasite, particularly in patients with strongyloidiasis.

[Endoscopic and extracorporeal shock wave lithotripsy of salivary calculi]

Shock wave lithotripsy of salivary gland stones has become more and more efficient in the treatment of sialolithiasis during the last years. We use two different methods in our hospital: Extracorporeal shock wave lithotripsy (ESWL) and endoscopically intracorporeal lithotripsy (EISL). The results of both therapies are compatible; 60-70% could be successfully treated. The indication is different due to the localisation of the salivary gland stone. Stones that are located in the glandula or very proximal in the duct should be fragmented by extracorporeal lithotripsy. Stones located in the duct and multiple intraductal stones should be treated by the intracorporeal method. Clinical experiments showed that some salivary stones do not fragment easily. The reason is still unknown. We examined the ability of fragmentation in relation to the physicochemical analysis of the stone. The stones were examined by infrared spectroscopy. This study revealed that pure carbonate apatite stones are more difficult to destroy than stones containing some protein.

Pericellular pH affects distribution and secretion of cathepsin B in malignant cells

Redistribution of lysosomes to the cell surface and secretion of lysosomal proteases appear to be general phenomena in cells that participate in local proteolysis. In the present study, we have determined whether malignant progression affects the intracellular distribution and secretion of the lysosomal protease cathepsin B in three model systems, each of which consists of cell pairs that differ in their degree of malignancy. The intracellular distribution of vesicles staining for cathepsin B was evaluated by immunofluorescent microscopy and the secretion of cathepsin B was evaluated by two complementary techniques: stopped assays of activity secreted into culture media; and continuous assays of activity secreted from viable (> or = 95%) cells growing on coverslips. We observed that the intracellular distribution of cathepsin B+ vesicles was more peripheral in the cells of higher malignancy in all three model systems and that active cathepsin B was secreted constitutively from these cells. Because an acidic pericellular pH has been shown to induce translocation of lysosomes in macrophages and fibroblasts, we evaluated the intracellular distribution of cathepsin B+ vesicles and secretion of cathepsin B in cell pairs incubated at slightly acidic pH. Acidic pericellular pH induced a redistribution of cathepsin B+ vesicles toward the cell periphery. In the more malignant cells, this resulted with time in reduced intracellular staining for cathepsin B and enhanced secretion of active cathepsin B. Translocation and secretion of cathepsin B were dependent on a functional microtubular system. Both the redistribution of cathepsin B+ vesicles toward the cell surface induced by acidic pH and the constitutive and acidic pH-induced secretion of active cathepsin B could be inhibited by microtubule poisons and stabilizers. We suggest that the redistribution of active cathepsin B to the surface of malignant cells and its secretion may facilitate invasion of these cells.

Cathepsin B expression and localization in glioma progression and invasion

The poor prognosis of human malignant gliomas is due to their invasion and recurrence, the molecular mechanisms of which remain poorly characterized. We have accumulated substantial evidence implicating the cysteine protease cathepsin B in human glioma malignancy. Increases in cathepsin B expression were observed throughout progression. In primary brain tumor tissue, transcript abundance (Northern blot analysis) increased in low-grade astrocytoma to high-grade glioblastoma from 3- to 6-fold, respectively, above normal brain levels. This increase correlated with increases in protein abundance (from + to ) as measured by immunohistochemistry. Furthermore, in glioblastoma cell lines increases in transcript abundance (ranging from 3- to 12-fold) were accompanied by increases in enzyme activity (44-133 nmol/min x mg protein). Altered subcellular localization was observed both immunohistochemically and by indirect immunofluorescence confocal microscopy and was found to correlate with increased grade. In addition, this increase in cathepsin B expression and altered subcellular localization correlated with histomorphological invasion and clinical evidence of invasion as detected by magnetic resonance imaging. These data support the hypothesis that cathepsin B plays a role in human glioma progression and invasion.

A lipoxygenase metabolite, 12-(S)-HETE, stimulates protein kinase C-mediated release of cathepsin B from malignant cells

The process of tumor cell invasion of the basement membrane is proposed to consist of three steps: attachment, local proteolysis and migration. 12-(S)-HETE, a 12-lipoxygenase metabolite of arachidonic acid, upregulates surface expression of integrin cytoadhesins and an autocrine motility factor receptor, suggesting that this metabolite may play an important regulatory function in tumor cell invasion. In the present study, we determined whether 12-(S)-HETE affects surface expression and/or release of cathepsin B, a cysteine protease that has been implicated in focal degradation of basement membrane. Secretion and distribution of cathepsin B was evaluated in two model systems for various stages of neoplastic progression: (i) murine B16 melanoma lines of low (B16-F1) and high (B16a) lung colonization potential, and (ii) immortalized and ras-transfected MCF-10 human breast epithelial cells that differ in their invasive capacities in vitro. In the B16a cells, 12-(S)-HETE induced release of native and latent cathepsin B activity and concomitantly reduced cell-associated cathepsin B immunoreactivity. In contrast, 12-(S)-HETE did not induce the release of cathepsin B from B16-F1 cells, suggesting that there may be an enhanced response to 12-(S)-HETE in more malignant cells. This was confirmed in the MCF-10 system, in which 12-(S)-HETE was able to induce the release of cathepsin B from the ras-transfected cells, but not from the immortal cells. A simultaneous reduction in staining for cathepsin B was observed in the ras-transfected cells, but not in their immortal counterparts. The release of cathepsin B may be mediated by PKC as pretreatment of B16a cells with the selective PKC inhibitor calphostin C, but not with the PKA inhibitor H8, prevented the stimulated release of cathepsin B. In B16a cells, the release of cathepsin B was accompanied by a translocation toward the cell periphery of vesicles staining for cathepsin B, resulting in focal areas of accumulation of cathepsin B. After 12-(S)-HETE stimulation of the ras-transfected MCF-10 cells, cathepsin B was distributed homogeneously on the apical surface. Thus, 12-(S)-HETE can upregulate the surface expression on tumor cells of proteins able to mediate each of the three steps of tumor cell invasion: adhesion, degradation, and migration.

Photolysis of ClNO adsorbed on MgO(100)

The 365 nm pulsed laser photolysis of nitrosyl chloride adsorbed on a rough MgO(100) surface at 90 K has been studied. Mass spectrometric detection was used to record time-of-flight (TOF) spectra by monitoring Cl+ and NO+. These ions can derive from parent ClNO, which fragments completely in the mass spectrometer, as well as from Cl and NO photofragments. The TOF distributions are considerably slower than for the corresponding gas phase photodissociation process. NO was also detected state selectively by using resonance enhanced multiphoton ionization (REMPI), and a channel corresponding to direct adsorbate photolysis was identified. The state selective detection of NO molecules that emerge from the surface following photolysis shows unambiguously that their rotational degrees of freedom reflect the surface temperature (Trot = 100−140 K), even at low coverages. At similar photolysis wavelengths, gas phase ClNO photodissociation is known to produce highly rotationally excited NO with a distinctive non-statistical distribution peaked at J″ = 46.5. Our studies suggest that, contrary to the gas-phase photolysis results, Cl and NO are not ejected rapidly following photolysis of surface-bound species on a repulsive potential energy surface. We postulate that ClNO grows in islands, with MgO defect sites serving as nucleation centers. Photofragment rotational and translational excitations are quenched efficiently due to strong attractive interactions that equilibrate NO to the surface temperature. Desorption of intact ClNO may also take place, but following (i.e., not during) the photolysis pulse. Such desorbed species can contribute to the TOF spectra, but not the REMPI spectra.

Membrane association of cathepsin B can be induced by transfection of human breast epithelial cells with c-Ha-ras oncogene

Alterations in trafficking and increases in expression of the lysosomal proteases cathepsins B, D and L have been observed in transformed cells and malignant tumors, including human breast carcinoma. ras and the related rab proteins participate in the vesicular transport processes required for normal trafficking of lysosomal enzymes. In addition, transfection of murine fibroblasts with the ras oncogene has been shown to increase the expression of cathepsins L and B. As human cancers are primarily epithelial in origin, we have investigated whether there are alterations in the trafficking and expression of cathepsin B in MCF-10 human breast epithelial cells transfected with wild-type and mutated ras. In all cells examined, i.e. mortal MCF-10M cells, immortal MCF-10A or MCF-10F cells, and transfected MCF-10A cells (transfected with the neomycin resistance gene (MCF-10Aneo) or cotransfected with wild-type proto-oncogenic ras (MCF-10AneoN) or mutated oncogenic ras (MCF-10AneoT)), levels of mRNA transcripts for cathepsin B were similar. However, alterations in trafficking of cathepsin B were observed in the cells transfected with oncogenic ras. In these cells there was an increased association of cathepsin B activity and cathepsin B protein with plasma membrane/endosomal fractions and a more peripheral distribution of immunofluorescent staining for cathepsin B. At the electron microscopic level, immunogold labeling for cathepsin B was localized to the cell membrane as well as to vesicles in the microvilli and adjacent to the cell membrane. In the parental MCF-10A cells, in contrast, cathepsin B was localized to vesicles in the perinuclear region. The cathepsin B associated with plasma membrane/endosomal fractions in the cells transfected with oncogenic ras was mature cathepsin B as demonstrated by immunoblot analysis. This was confirmed further by showing an absence of peripheral immunofluorescent staining in these cells using an antibody specific for the propeptide of cathepsin B. Thus, we have demonstrated by multiple techniques that transfection of human breast epithelial cells with oncogenic ras results in alterations in the trafficking of cathepsin B similar to those observed previously in human and animal tumors of both epithelial and mesenchymal origin.

Pyomyositis: cervical localization

We describe an uncommon case of cervical pyomyositis in a 60-year-old woman without predisposing factors, admitted for cervicobrachial neuralgia with fever and paravertebral contracture. Ultrasonography and computed tomography (CT) showed a collection in the left longissimus capitis. Ultrasonography guided needle aspiration yielded thick pus, which cultured Staphylococcus aureus. Our patient completely recovered after antibiotherapy. Pyomyositis is rare and most commonly affects rhizomelic muscles (cervical localization is extremely rare) and occurs in patients with predisposing factors. Staphylococcus aureus is responsible for over 85% of cases; ultrasonography and CT scan are useful for abscess localization and aspiration.

Fibroblastic rheumatism: clinical, histological, immunohistological, ultrastructural and biochemical study of a case

We report a case of fibroblastic rheumatism (FR). Only eight other cases of this recently described entity have been reported previously. FR is characterized by polyarthralgia and joint stiffness without joint destruction, associated with cutaneous nodules and sclerodactyly. Histology shows an increase in the number of fibroblasts and marked dermal fibrosis. Rheumatological and skin manifestations may improve with corticosteroid therapy. In our patient, immunohistochemical studies of involved and uninvolved skin showed an increase in fibronectin and tenascin deposition. In the dermis, the hyperplastic cells had phenotypic features of muscle, suggesting myofibroblastic differentiation. Ultrastructural study showed an increase in active fibroblastic cells with features of myofibroblasts. A hyperproliferative capacity was observed in fibroblasts cultured from involved skin. Biochemical studies of the production of collagen and non-collagen proteins were performed on these cultured cells, and showed a reduction in collagen and non-collagen protein synthesis by FR fibroblasts. Thus, FR appears to differ from other fibrotic skin diseases such as scleroderma, in that dermal fibrosis may be due predominantly to fibroblast proliferation with myofibroblastic differentiation without any increase in collagen synthesis.

Hereditary progressive dystonia with diurnal fluctuation (Segawa's syndrome)--an unusual case

A young girl with hereditary progressive dystonia with diurnal fluctuation or Segawa's syndrome, completely handicapped and confined to a wheelchair between the age of 5 and 9, revealed an unusually slow response to levodopa. The ability to walk returned only after 12 to 14 months of treatment. Apart from peculiarities of behaviour due to longstanding immobility and ensuing parental overprotection, there were no psychological or mental abnormalities. Other organic diseases were ruled out. A series of regular follow-ups over the course of 7 years was performed. While residual and irregular day-to-day variation of functional capacities almost disappeared after conversion to a preparation with a decarboxylase inhibitor, some mild neurological abnormalities and a slight choreic hyperkinesia persisted with doses providing functional results. The patient today leads an almost normal teenage life and has performed well in school.

Multicentric reticulohistiocytosis. Immunohistological and ultrastructural study: a pathology of dendritic cell lineage

A case of multicentric reticulohistiocytosis is presented with extensive immunohistochemical study of the infiltrate in both paraffin and cryostat sections. Factor XIIIa dermal dendrocyte marker was demonstrated in the cytoplasm of histiocytes, which has not been reported previously in this disease. In addition, the S100 protein stained positive. This immunophenotyping study suggests a dermal dendrocyte lineage with an unusual expression of S100 protein.

Cysteine endopeptidases and their inhibitors in malignant progression of rat embryo fibroblasts

Cathepsins B and L and their endogenous inhibitors were evaluated in rat embryo fibroblast lines which have been developed as a model system for the study of malignant progression and metastatic capability. Three groups of lines were analyzed: 1) immortalized/non-tumorigenic, 2) tumorigenic/metastatic lines transfected with c-Ha-ras, and 3) metastatic revertants transfected with c-Ha-ras+the E1A region of adenovirus type 2. The metastatic revertants are tumorigenic, but non-metastatic. No correlation was seen between tumorigenicity and metastatic potential and the level of expression of cathepsin B or the subcellular distribution of cathepsins B and L. However, cathepsin L activity was increased 2-fold in the 4R metastatic line. Although transfection of aneuploid 3T3 fibroblasts with ras has been shown to increase the expression of cathepsin L and cathepsin B, transfection of the diploid rat embryo fibroblasts with ras did not correlate with increased expression of cathepsin L or cathepsin B. However, ras transfection of the rat embryo fibroblasts was associated with a significant (4-15-fold) decrease in the activity of heat-stable cysteine endopeptidase inhibitors. Thus, in tumorigenic rat embryo fibroblast lines, regulation of the activities of cysteine endopeptidases by their endogenous inhibitors may be compromised, resulting in increased effective activities of the cysteine endopeptidases.

[Lupus chorea revealing. Study in magnetic resonance imaging. Success of plasma exchanges after resistance to pulsed cortisone]

Chorea as a manifestation of SLE is infrequent (1% of all cases of SLE). A new case is reported herein. The patient, a seventeen-year-old female, was admitted with a one-week history of choreic movements of the left half of the body and arthritis of both wrists. Biologic findings confirmed the diagnosis of SLE with presence of an antiprothrombinase circulating anticoagulant. Findings upon cerebral CT scan and magnetic resonance imaging were normal. Clinical symptoms worsened despite corticosteroids in a daily dosage of 1 mg/kg with three pulses of 800 mg methylprednisolone. High-dose neuroleptic therapy was given and three plasma exchanges were performed. A dramatic improvement in clinical symptoms and biological anomalies occurred and persisted during follow-up which now exceeds one year. The lack of MRI anomalies suggests that the pathogenesis of SLE-associated chorea involves functional neurone activation by immune complexes; the dramatic effectiveness of plasma exchanges may obviate the need for using immunosuppressant agents in patients who fail to respond to corticosteroids.

Knee arthritis revealing acute leukemia in a patient with rheumatoid arthritis

We report one case of leukemic synovitis in a patient with a 40-year history of rheumatoid arthritis. The synovial fluid sample and synovial biopsy specimen showed myeloblastic cells. So, leukemic synovitis can be suspected in a patient with inflammatory rheumatism and adequate diagnostic procedures should be carried out.

Possible interaction of fluoroquinolones with the benzodiazepine-GABAA-receptor complex

1. The possible involvement of the benzodiazepine (BZD)-GABAA-receptor complex in mediating CNS stimulatory effects of fluoroquinolones was tested in vitro, in a binding inhibition assay and in vivo, in a clinical drug interaction study using electro-encephalogram (EEG) monitoring. 2. The specific binding of [3H]-flunitrazepam to rat synaptic brain membranes was inhibited by various fluoroquinolones in a concentration-dependent manner. 3. Ofloxacin had CNS-stimulating effects as revealed by the EEG which were slightly augmented by flumazenil but reversed by coadministration of midazolam. 4. In conclusion, our findings suggest that clinically observed CNS adverse effects of fluoroquinolones could be mediated at least in part through interaction with the BZD-GABAA-receptor complex and may be controlled by BZD agonist administration.