Interaction between carbamazepine and bromperidol

OBJECTIVE

The interaction between carbamazepine and bromperidol was studied in 13 schizophrenic inpatients.

METHODS

Before carbamazepine addition, the subjects were taking bromperidol 12-24 mg.day-1 for 1-20 weeks. Carbamazepine 400 mg.day-1 was coadministered for 4 weeks, and blood samplings were performed before carbamazepine addition and at weekly intervals after the addition. Plasma concentrations of bromperidol and its reduced metabolite were measured by high-performance liquid chromatography.

RESULTS

Carbamazepine significantly decreased plasma concentrations of both bromperidol and reduced bromperidol for all weeks. On average, the plasma concentrations of bromperidol and reduced bromperidol at 4 weeks were 37% and 23% of the corresponding precarbamazepine values. Despite these decreases in plasma concentration, the Clinical Global Impression scores decreased slightly but significantly after carbamazepine addition.

CONCLUSION

The present study suggests that carbamazepine decreases plasma concentrations of bromperidol and its reduced metabolite by inducing the metabolism of these compounds. Nevertheless, adjunctive carbamazepine may be useful for schizophrenic patients treated with bromperidol.

Cytosolic factors in mitochondrial protein import

In vitro import studies have confirmed the participation of cytosolic protein factors in the import of various precursor proteins into mitochondria. The requirement for extramitochondrial adenosine triphosphate for the import of a group of precursor proteins seems to be correlated with the chaperone activity of the cytosolic protein factors. One of the cytosolic protein factors is hsp70, which generally recognizes and binds unfolded proteins in the cytoplasm. Hsp70 keeps the newly synthesized mitochondrial precursor proteins in import-competent unfolded conformations. Another cytosolic protein factor that has been characterized is mitochondrial import stimulation factor (MSF), which seems to be specific to mitochondrial precursor proteins. MSF recognizes the mitochondrial precursor proteins, forms a complex with them and targets them to the receptors on the outer surface of mitochondria.

Hallucinations after a therapeutic dose of benzodiazepine hypnotics with co-administration of erythromycin

A case of repetitive hallucinations during treatment with a therapeutic dosage of triazolam (0.25 mg/day) and nitrazepam (5 mg/day) is presented. The patient suffered from acute pneumonia and chronic renal failure. Such non-psychotic symptoms as anxiety, tremor and depressed feeling were observed initially. However, after co-administration of erythromycin (600 mg/day), visual hallucinations and abnormal bodily sensations developed repeatedly after each administration of triazolam or nitrazepam. This report suggests that benzodiazepine hypnotics even at a therapeutic dosage with co-administration of erythromycin causes serious psychotic symptoms in vulnerable patients with physical complications.

Possible inhibitory effect of diazepam on the metabolism of zotepine, an antipsychotic drug

Effects of smoking and cytochrome P450 2C19 (CYP2C19) status on the single dose kinetics of zotepine and pharmacokinetic interaction between zotepine and diazepam were investigated. In 14 healthy volunteers, the pharmacokinetics of zotepine after a single oral 25 mg dose were compared between eight smokers and six non-smokers, or between seven extensive metabolizers (EMs) and seven poor metabolizers (PMs) of S-mephenytoin. There was no significant difference in any pharmacokinetic parameters between smokers and non-smokers, or between the EM and PM groups. In 17 patients treated with zotepine 80-340 mg/day, intra-individual changes in plasma concentrations of zotepine caused by coadministration of diazepam 10 mg/day for 2 weeks were examined. Plasma concentrations of zotepine were significantly increased after coadministration of diazepam (P < 0.05). Consequently, it is suggested that neither smoking nor CYP2C19 status affects the metabolism of zotepine. The elevation in plasma concentrations of zotepine after coadministration of diazepam may be a result of competitive inhibition of zotepine metabolism by diazepam via other isoenzyme than CYP2C19, e.g., CYP3A4.

No interaction between desipramine and bromperidol

1. The authors studied the effects of coadministration of desipramine, which is a substrate of CYP2D6, on plasma concentrations of bromperidol and its reduced metabolite (reduced bromperidol). Clinical changes were also evaluated by the CGI and UKU. 2. The subjects were 13 schizophrenic inpatients receiving bromperidol 12.24 mg/day for 1.20 weeks. Desipramine 50 mg/day was coadministered for 1 week, and blood samplings and clinical ratings were performed before and after the coadministration. 3. Plasma concentrations of bromperidol and reduced bromperidol were measured by a HPLC method. 4. Desipramine coadministration did not affect plasma concentration of bromperidol (9.6 +/- 4.5 vs. 9.6 +/- 2.8 ng/ml) nor that of reduced bromperidol (2.8 +/- 2.5 vs. 2.8 +/- 2.1 ng/ml). 5. There was no significant change in the CGI scores nor UKU scores after desipramine coadministration. 6. The present study thus suggests that there is no interaction between desipramine and bromperidol.

Two-dimensional electrophoretic studies on down-regulated intracellular transferrin in human fibroblasts immortalized by treatment with either 4-nitroquinoline 1-oxide or 60Co gamma rays

The immortalization of human cells is an important early step of carcinogenesis. To investigate the mechanisms of immortalization, we established three immortalized human fibroblast cell lines by treatment with either 4-nitroquinoline 1-oxide (4NQO) or 60Co gama rays. Using two-dimensional gel electrophoresis (2-D PAGE), we identified proteins which are down-regulated in these immortalization cell lines. Their isoelectric points ranged between 5.5 and 6.3, and their molecular masses were approximately 80 kDa. The proteins were also decreased in another human fibroblast cell line immortalized with simian virus 40 (SV40) and two human cervical cell lines. The proteins were present in a cytoskeletal fraction, reacted with anti-transferrin antibody and some of them were phosphorylated. The proteins were identified as transferrin. Although the 2-D PAGE patterns of our proteins and serum transferrin of different origin were distinct from each other, their isoelectric points and molecular weights were similar. We implicate some functions of intracellular transferrin, other than an iron transporter, in immortalization of human cells and discuss a new aspect of transferrin metabolism in the cells.

Protein import into mammalian mitochondria. Characterization of the intermediates along the import pathway of the precursor into the matrix

We have characterized several intermediates in the mitochondrial import stimulation factor (MSF)-dependent import into mammalian mitochondria of a matrix-targeted precursor, preadrenodoxin (pAd). In the first step, pAd docks onto the 37-kDa protein of the outer membrane (OM37) as a complex with MSF (stage I intermediate). It is then transferred to the import pore of OM in the presence of ATP, but in the absence of Deltapsi across the inner membrane (IM), to form stage II intermediate. Depletion of matrix ATP in the presence of both extramitochondrial ATP and Deltapsi induces accumulation of stage III intermediate, which is a mixture of the precursor with different intramitochondrial localizations: the precursor whose presequence had crossed either OM (IIIa) or both OM and IM (IIIb), but with a bulk portion remaining exposed to the cytosol and the precursor whose presequence had crossed both membranes, but with a residual portion staying within the intermembrane space (IIIc). These intermediates are on the correct import pathway and are characteristic in their protease accessibility, salt extractability, and antibody accessibility, as well as in their energy requirement for the chase reaction.

A method for rapid determination of zotepine by gas chromatography-mass spectrometry

A rapid and sensitive method using solid-phase extraction and gas chromatography-mass spectrometry (GC-MS) has been developed for the determination of zotepine (ZTP), an atypical neuroleptic, in human plasma. The detection limit of ZTP was 1 microgram/L. Standard curves over the concentration range from 2.5 to 100 micrograms/L had a good linearity. Intraassay variability ranged from 2.2 to 3.3% and interassay variability from 3.5 to 6.6% at the concentration range of 5-75 micrograms/L. Our preliminary data of single-dose kinetics of ZTP by using this method suggested that the peak time and elimination half-life was much longer than previously reported, and that there appeared to be a second peak after 10-12 h of ZTP administration, indicating the possibility of the presence of enterohepatic recirculation.

Mutation in p53 and de-regulation of p53-related gene expression in three human cell lines immortalized with 4-nitroquinoline 1-oxide or 60Co gamma rays

In vitro models of malignant transformation of human cells may provide considerable insight into the mechanisms of multi-step carcinogenesis. It is well established that normal human cells must be immortalized before they can be malignantly transformed; however, they are stringently destined for aging and are rarely immortalized. The mechanism of cellular aging and immortalization is still unknown. We detected expression of only mutated p53 mRNA by direct sequencing of the reverse-transcribed mRNA in 3 human cell lines immortalized either with 4-nitroquinoline 1-oxide or with 60Co gamma rays. Consequently, only the mutated pS3 protein was expressed in each immortalized cell line. The expression of sdiI/p21 and mdm2, both of which are positively regulated by wild-type p53, was significantly down-regulated in the immortalized cell lines, resulting in over-expression of cdk2 and cdk4. Introduction of the sdiI/p21 gene into these cells was followed by a remarkable decrease in their ability to synthesize DNA. These results indicate that the p53 cascade may play an important role in the immortalization of human cells.

Interleukin-6 gene expression is preferentially restricted in VLA-5-MPC-1- immature but not in VLA-5+MPC-1+ mature myeloma cells

Interleukin-6 (IL-6) is essential for the proliferation of myeloma cells, and IL-6 is considered to be produced from not only myeloma cells themselves but also microenvironments including stromal cells. To clarify which subpopulation of myeloma cells can produce IL-6, we examined IL-6 mRNA expression in immature and mature myeloma cells and normal plasma cells by RT-PCR. IL-6 mRNA expression was found in all (10/10) specimens of sorted VLA-5-MPC-1- immature myeloma cells and 27% (3/11) of VLA-5-MPC-1+ myeloma cells. On the contrary, no IL-6 mRNA was expressed in VLA-5+MPC-1+ mature myeloma cells (0/4) and CD19+CD56- normal plasma cells (0/5). IL-6R gene expression was detected in all normal and malignant plasma cells without exception. Therefore, these findings suggest that IL-6 production is preferentially restricted in immature not mature myeloma cells, and this may explain why immature myeloma cells show greater proliferative activity.

Effects of carbamazepine coadministration on plasma concentrations of trazodone and its active metabolite, m-chlorophenylpiperazine

Effects of carbamazepine coadministration on plasma concentrations of trazodone and its active metabolite, m-chlorophenylpiperazine (m-CPP) were studied in six depressed patients treated with trazodone. The daily dose of trazodone was 150 mg in three cases and 300 mg in three cases. Carbamazepine, 400 mg/day, was coadministered for 4 weeks, and blood samples were taken before carbamazepine addition and at weekly intervals after the addition. Carbamazepine significantly (p < 0.01) decreased plasma concentrations of not only trazodone but also m-CPP at each week. On the average, plasma concentrations of trazodone and m-CPP at 4 weeks were 24 and 40% of the corresponding precarbamazepine values. This study thus suggests that carbamazepine coadministration decreases plasma concentrations of trazodone and m-CPP by inducing the metabolism of these compounds.

Selective expression of mutated p53 in human cells immortalized with either 4-nitroquinoline 1-oxide or 60Co gamma rays

Many studies on in vitro transformation of human cells indicate that the cells must be immortalized before they can be neoplastically transformed, indicating that immortalization is a critical step in multistep neoplastic transformation of human cells. We immortalized three human cell lines by repeated treatment with either 60Co gamma rays or a chemical carcinogen, 4-nitroquinoline 1-oxide, and found that all three immortalized cell lines have mutations in the tumor suppressor gene, p53. Direct sequencing of the reverse-transcribed mRNA and immunoprecipitation of p53 protein revealed that mutant p53 is selectively expressed in all the immortalized cell lines, whereas the genomic fragments of the immortalized cells contain wild-type and mutated p53 alleles. Although the mutated p53 is selectively expressed in the immortalized cells, expression of the wild-type p53 was induced by treatment of the cells with a hypomethylating reagent, 5-azacytidine, indicating that the wild-type p53 allele might be inactivated by hypermethylation of DNA. Actually, the entire genomic locus including the promoter region of p53 is hypermethylated in all the immortalized cell lines. Expression and phosphorylation of Rb was normal in these three cell lines. Thus, inactivation of both wild type p53 alleles and selective expression of mutated p53 seem to be key factors in the immortalization of human fibroblasts.

Reinitiation of protein translocation across the endoplasmic reticulum membrane for the topogenesis of multispanning membrane proteins

The reinitiation of the translocation of the growing nascent chain across the endoplasmic reticulum membrane is essential for the topogenesis of multispanning membrane proteins. We investigated the requirements for the reinitiation process using model proteins in which systematically designed sequences were inserted after two preceding topogenic sequences, namely the N-terminal signal sequence (S) and stop transfer sequence (St). The model proteins were translated in vitro in the presence of rough microsomes, and the final topology of the proteins in the microsomal membrane was examined by proteolytic digestion. The structural requirements for S and the reinitiation sequence (R) overlapped to some extent, but substantial differences were noticed. When St and R were separated by a short cytoplasmic segment (58 amino acids), the efficiency of the reinitiation was not affected by the concentration of the signal recognition particle (SRP) in the translation system, even though the sequence inserted as R was an SRP-dependent signal sequence. However, when the cytoplasmic segment was longer (100 amino acids), the reinitiation efficiency was reduced, and the SRP improved the overall efficiency as well as impaired the accessibility of the processing site after the R to the signal peptidase.

Persistence of hepatitis C virus RNA in established human hepatocellular carcinoma cell lines

The persistence of the viral RNA of hepatitis C virus (HCV) was examined in 13 hepatocellular carcinoma (HCC) and two hepatoblastoma cell lines by reverse transcription followed by the polymerase chain reaction (RT-PCR). HCV RNA was detected in three HCC lines (JHH-1, JHH-4, and JHH-6) and negative-strand viral RNA was found in JHH-4, indicating that there is a putative replicative intermediate of HCV in JHH-4 cells. To rule out the possibility of contamination, the partial nucleotide sequences of HCV-specific PCR products of these three cell lines were determined. The clone from JHH-1 belonged to genotype 1 (1a or 1b), and the clones from JHH-4 and JHH-6 belonged to genotype 2b, but their sequences differed from each other. These cell lines may be useful for studies related to HCV.

Establishment and characterization of a human colon cancer cell line, OUMS-23, from a patient with familial adenomatous polyposis

A human colon carcinoma cell line designated OUMS-23 has been established from metastatic pericardial fluid of a male familial adenomatous polyposis patient with colon cancer. Since 1984, the epithelial cells have been maintained in culture. Ultrastructural studies revealed the presence of numerous microvilli on the cell surface and desmosomes between the adjacent cells. The cells secreted carcinoembryonic antigen into the culture medium (15 ng/10(6) cells-1 24 h-1). The cells expressed heat-stable placental-type-like alkaline phosphatase, whereas the normal counterparts expressed tissue-unspecific alkaline phosphatase. Karyotypic analysis showed that the cell line was of human origin and that the chromosome number was broadly distributed between 53 and 118. Southern blot analysis of the APC gene revealed no abnormalities in OUMS-24 cells, while Northern blot analysis demonstrated that the expression of the gene was about one-half that of the normal human fibroblasts. No mutations at the "hot spots" of codons 12 and 61 of H-, K- and N-ras proto-oncogenes were detected in the cells. The cells could grow in soft agar at a cloning efficiency of 6.5%, and upon transplantation into nude mice the cells formed tumors, which were diagnosed as differentiated adenocarcinoma.

Cytoplasmic chaperones determine the targeting pathway of precursor proteins to mitochondria

Two ATP-dependent cytosolic chaperones, mitochondrial import stimulation factor (MSF) and hsp70, are known to be involved in the import of precursor proteins into mitochondria. Hsp70 generally recognizes unfolded proteins, while MSF specifically recognizes mitochondrial precursor proteins and targets them to mitochondria in a NEM-sensitive manner. Here we analyzed the relative contribution of these chaperones in the import process and confirmed that the precursor proteins are targeted to mitochondria via two distinct pathways: one requiring MSF and the other requiring hsp70. Both pathways depend on distinct proteinaceous components of the outer mitochondrial membrane. The MSF-dependent pathway is NEM-sensitive and requires the hydrolysis of extra-mitochondrial ATP for the release of MSF from the mitochondrial import receptor, whereas the hsp70-dependent pathway is NEM-sensitive and does not require extra-mitochondrial ATP. The NEM-insensitive, hsp70-dependent import became NEM-sensitive depending on the amount of MSF added. The relative importance of the two pathways appears to be determined by the affinities of MSF and hsp70 for the precursor proteins.

Identification of early plasma cells in peripheral blood and their clinical significance

In the peripheral blood (PB) we detected so-called early plasma cells that might already be committed to entering the bone marrow (BM). By two-colour staining with FITC-anti-CD38 antibody, their intensity (CD38++) of expression of CD38 antigen was between that of germinal centre (GC) B cells (low expression (CD38+)) and that of BM plasma cells (high expression (CD38++)), and their phenotype was CD38++ CD19+ CD10- CD20- CD21+ CD24- CD39+ CD5- VLA-4+ VLA-5- MPC-1- without expression of surface membrane IgM (SmIgM). Morphological and immunological examination of the sorted cells confirmed that they were plasmacytoid cells with expression of cytoplasmic IgG (cIgG). Variations of these early plasma cells were examined in various diseases. In active systemic lupus erythematosus, bacterial septicaemia and liver cirrhosis, early plasma cell levels were significantly increased in PB, and after subsidence of such inflammation (inactive states) these cells returned to normal levels. In contrast, normal early plasma cells were significantly suppressed in myelomas, whilst normal or slightly increased numbers of early plasma cells was found in benign monoclonal gammopathy (BMG). In addition, the number of normal early plasma cells returned to a normal level in myeloma cases with complete responses. Therefore, early plasma cells were identified phenotypically, and an increase and decrease in these cells in PB may reflect mobilization and suppression, respectively, of activated B cells into BM plasma cells.

Immortalization of human cells and its mechanisms

One of the contributions of in vitro neoplastic transformation studies on human cells is the confirmation that cells become malignant by a multistep process. In this review, we use the term "neoplastic transformation" to indicate that the cells become capable of forming a histologically malignant tumor, that is, one that invades and/or erodes normal tissue and is serially transplantable in a susceptible animal host. Phenotypically, the cells first become immortalized and then neoplastic. If normal human cells do not overcome aging by becoming immortalized, they cannot be neoplastically transformed. However, normal human cells are stringently destined to cellular aging and very rarely become immortalized by oncogenic DNA viruses (SV40, papillomavirus types 16 and 18, adenovirus types 5 and 12), chemicals, X-rays, or spontaneously. Once human cells get immortalized, they relatively easily become neoplastic. Evidence shows that immortalization is a critical step in the neoplastic transformation process of human cells. Therefore, investigation of the mechanisms of immortalization is indispensable in understanding the multistep carcinogenesis of human cells. Although the precise mechanisms of immortalization are unknown at present, data indicate that the p53 cascade appears to be important for the immortalization of human cells. The loss of functions of normal p53 may induce genomic instability, resulting in mutations of some other unknown genes that are more directly involved in the immortalization of human cells. These unknown genes, which are presumably located at chromosomes 1, 4, 6, 7, 9, 11, 13, 17, 18, and X are now under extensive investigation.

Telomere elongation observed in immortalized human fibroblasts by treatment with 60Co gamma rays or 4-nitroquinoline 1-oxide

Telomeres are the tandemly repeated (TTAGGG)n sequences that make up the structural and functional ends of all chromosomes in mammals. Many lines of evidence indicate that telomeres stabilize chromosomes, prevent aberrant recombination, and direct chromosome attachment to the nuclear membrane. Since DNA polymerase requires a labile primer to initiate unidirectional 5'-3' DNA synthesis, some bases at the 3' end of each template strand are not copied unless special mechanisms bypass this end-replication problem. To overcome this problem, most eukaryotic cells use telomerase, an enzyme that elongates telomeres. However, this enzyme has not been detected in normal human cells, and these cells lose telomeres with cell division. Cellular senescence might be the result of this loss. Thus, activation of telomerase seems to be critical for the immortalization of human cell lines. In addition, substantial evidence indicates that immortalization in itself is a rate-limiting step for the malignant transformation of human cells. We have treated normal human fibroblasts (AD387, KMS-6, and OUMS-24 lines) intermittently with either 60Co gamma rays or 4-nitroquinoline 1-oxide (4NQO) during serial subcultivations, and have obtained three immortalized cell lines, SUSM-1, KMST-6, and OUMS-24F. In KMS-6 and OUMS-24, the mean terminal restriction fragment length significantly decreased as the population-doubling level increased. The rate of telomere loss was 40 and 50 bp/population doubling in the KMS-6 and OUMS-24 cell lines, respectively. Once these normal cell lines were immortalized, their telomeres became elongated. Similar data were obtained for AD387 cells and their immortalized SUSM-1 cells. These results suggest that telomeres play a critical role in cellular senescence and in the immortalization processes of human cells.

High proportions of VLA-5- immature myeloma cells correlated well with poor response to treatment in multiple myeloma

Using two-colour phenotypic analysis with anti-CD38 antibody, human myeloma cells can be classified into VLA-5- immature and VLA-5+ mature cells. We examined the relationship between variations of these subpopulations and clinical responses during treatment in multiple myeloma (MM). 39 patients with MM were treated with combined chemotherapy. First estimation of clinical responses after induction therapy showed that early clinical responses were correlated with the percentage of immature myeloma cells present after induction therapy (P < 0.01), not at diagnosis. After three courses of cyclic maintenance therapy, immature myeloma cells significantly decreased in proportion along with a decrease in total myeloma cells in maintained or more responsive cases (P < 0.01). On the other hand, immature myeloma cells were still found in high proportions in nonresponsive cases with no change (NC) or minor response (MR) (P < 0.01). Furthermore, in relapsing cases from partial response (PR) or progressive disease (PD) from nonresponsive cases, immature myeloma cells increased markedly. Therefore these results show that high proportions of VLA-5- immature myeloma cells remaining after induction therapy and during maintenance therapy correlate well with a declining clinical course of MM during maintenance therapy.

Intracellular targeting of lysosomal cathepsin D in COS cells

Cathepsin D carries a mannose 6-phosphate sorting signal which is recognized by a specific mannose 6-phosphate receptor, presumably at the site of the trans Golgi network, which segregates cathepsin D from the secretory proteins, and results in targeting of the enzyme to the acidic prelysosomal compartments and lysosomes in mammalian cells. Recent evidence implies that another sorting signal resides within the polypeptide backbone of the precursor cathepsin D. To evaluate the role of the propeptide region of cathepsin D in mannose 6-phosphate receptor-independent targeting to lysosomes, we prepared a deletion mutant of rat cathepsin D lacking the propeptide portion and analyzed its intracellular targeting mechanism after transfection of the mutant cDNA as well as the wild-type cDNA into COS cells. The glycosylated mutant protein was retained intracellularly, and extracellular release of mutant protein was not observed after a 48 h chase. A cell fractionation experiment demonstrated that in the cells expressing the wild-type cathepsin D, the processed form of 44 kDa cathepsin D was recovered in the dense lysosomal fraction. In contrast, in the cells expressing the mutant protein, virtually all of the cell-associated cathepsin D was present in the light fraction which was enriched in the marker enzyme NADPH cytochrome c reductase, and this molecular form of cathepsin D was not observed in the dense lysosomal fraction. An immunofluorescence study revealed that the deletion mutant protein was accumulated within the endoplasmic reticulum, unlike the wild-type protein. These results suggest that the mutant cathepsin D is not correctly recognized by the intracellular sorting system in the endoplasmic reticulum, implying that the propeptide region of cathepsin D is essential for the export of cathepsin D from the endoplasmic reticulum.

Enantioselective determination of mianserin and its desmethyl metabolite in plasma during treatment of depressed Japanese patients

A method for the analysis of the enantiomers of mianserin and its main metabolite desmethylmianserin in plasma using a chiral AGP high performance liquid chromatography column is described. In the majority of 66 depressed Japanese patients, the concentration of the more active S(+)-mianserin was higher than that of the R(-)-enantiomer. The mean S/R ratio was 1.9 +/- 0.9 (SD) (range 0.5-4.8). The concentration of S(+)-varied between 19 and 223 nM, while that of the R(-)-mianserin varied between 14 and 72 nM. Among 42 of the 66 plasma samples in which the enantiomers of desmethylmianserin could be measured, the R-form predominated in all but one. S-Desmethylmianserin was in most of the samples present in concentrations of < 10 nM (limit of detection). Analysis of the enantiomers of mianserin and desmethylmianserin might allow the establishment of a closer relationship between plasma levels and clinical effects.