Identification of small molecules that promote human embryonic stem cell self-renewal.

Human embryonic stem cells (hESCs) and induced pluripotent cells have the potential to provide an unlimited source of tissues for regenerative medicine. For this purpose, development of defined/xeno-free culture systems under feeder-free conditions is essential for the expansion of hESCs. Most defined/xeno-free media for the culture of hESCs contain basic fibroblast growth factor (bFGF). Therefore, bFGF is thought to have an almost essential role for the expansion of hESCs in an undifferentiated state. Here, we report identification of small molecules, some of which were neurotransmitter antagonists (trimipramine and ethopropazine), which promote long-term hESC self-renewal without bFGF in the medium. The hESCs maintained high expression levels of pluripotency markers, had a normal karyotype after 20 passages, and could differentiate into all three germ layers.

Influence of comedication on serum concentrations of aripiprazole and dehydroaripiprazole.

Aripiprazole, a relatively new antipsychotic drug, is metabolized by cytochrome P450 3A4 (CYP3A4) and CYP2D6 to an active metabolite, dehydroaripiprazole. As studies on pharmacokinetic drug interactions with aripiprazole are so far limited, the aim of the present study was to investigate the impact of comedication on serum concentrations of aripiprazole and dehydroaripiprazole in psychiatric patients in a clinical setting. A therapeutic drug monitoring database was screened for patients receiving aripiprazole tablets as part of their treatment. Of the 361 samples included, 78% were from patients receiving comedication. The remaining 79 samples constituted the control group. Steady-state dose-adjusted serum concentrations (concentration to dose ratios, C:D ratios) of aripiprazole, dehydroaripiprazole and the sum of aripiprazole and dehydroaripiprazole, and the metabolic ratio (dehydroaripiprazole/aripiprazole) in the different comedication groups were compared with controls. Coadministration of a CYP3A4 inducer resulted in approximately 60% lower mean C:D ratios of aripiprazole, dehydroaripiprazole, and the sum of aripiprazole and dehydroaripiprazole (P < 0.05, P < 0.01, and P < 0.01, respectively). Combination with a CYP2D6 inhibitor resulted in a 45% higher mean C:D ratio of aripiprazole (P < 0.05), with no effect on the C:D ratio of dehydroaripiprazole. When aripiprazole was coadministered with alimemazine or lithium, a 56% (P < 0.01) and 43% (P = 0.05) higher mean C:D ratio of aripiprazole, respectively, was observed. Olanzapine, risperidone injections, escitalopram, or lamotrigine also had statistically significant effects on aripiprazole disposition but to a lesser extent. In conclusion, concurrent treatment with CYP3A4 inducers, CYP2D6 inhibitors, alimemazine, or lithium resulted in changes in the systemic exposure of aripiprazole between 40% and 60%. This is of such a magnitude that dose adjustments of aripiprazole may be required.

A new powerful antibacterial synergistic combination of trimethoprim and trimeprazine.

The antihistaminic phenothiazine trimeprazine (Tz) was found to exhibit significant antibacterial activity on the basis of in vitro and in vivo tests. For the study of synergism due to a combination between Tz and trimethoprim (Tm), drug soaked filter paper discs were placed on young culture lawns of sensitive bacteria on nutrient agar plates. Calculation of the area of inhibition zones for determining the degree of synergism between Tz and Tm showed the increase to be statistically significant (p<0.01) when compared with their individual effects. By the checkerboard assessment procedure, the fractional inhibitory concentration (FIC) index was found to be 0.18, confirming synergism. The protective capacity of this combination was then assessed in Swiss white mice using S. typhimurium as the challenge bacterium, and the level of bacterial load was determined from infected autopsied animals. Statistical analysis of the data by students 't' test finally proved that a combination of Tz+Tm was highly synergistic.

Phenothiazine-induced increase in thyroid autoantigens and costimulatory molecules on thyroid cells: a pathophysiological mechanism for drug-induced autoimmunity?

We have previously demonstrated (J Immunol 1995; 154:3593) that MHC class II antigens can be induced on thyroid epithelial cells (TEC) by alimemazine, a member of the phenothiazine group. Although this expression of MHC class II antigens on TEC confers the theoretical ability to behave as antigen-presenting cells (APC), the simultaneous expression of self antigens and co-receptor(s) must also occur for efficient presentation of self antigens. Therefore, we investigated whether alimemazine applied at pharmacologic doses would modify the expression of thyroid antigens, and simultaneously, the expression of intercellular adhesion molecule-1 (ICAM-1), B7, and LFA-1 co-receptors in human TEC in culture. Using polymerase chain reaction (PCR) amplification and Northern blot analysis, we showed that alimemazine induces increases in thyroglobulin (Tg) and thyroid-stimulating hormone receptor (TSH-R) cDNA, within the first 2 h following its addition. This phenomenon is followed 48 h later by an increase of Tg and TSH-R protein expression on the surface of TEC. Furthermore, increases in the expression of ICAM-1 and B7 co-receptors were concomitantly observed. These results suggest that alimemazine, a drug currently used in paediatrics, could play a role in the induction and perpetuation of thyroid autoimmune disorders by transforming TEC into functional APC.

Phenothiazine induces de novo MHC class II antigen expression on thyroid epithelial cells. A new mechanism for drug-induced autoimmunity.

Autoimmune responses are initiated by MHC class II-restricted T cell responses directed against tissue-specific autoantigens. Furthermore, HLA-DR expression in thyroid epithelial cells is a prominent feature of autoimmune thyroid disease. In the present work, we were particularly interested in a phenothiazine, a neuroleptic and anti-depressant drug of pharmacologic importance named alimemazine. Our interest in this compound stems from previous findings of immune effects of this and other phenothiazines. We demonstrate that MHC class II Ags can be experimentally induced on thyroid cells by pharmacologic concentrations of alimemazine, a drug commonly used in psychiatry. In contrast, MHC class II Ags were not induced on the lymphoid cell lines Raji and Jurkat. Expression of MHC class II Ag on the surface of the cloned human thyroid cell hybridoma, GEJ, was demonstrated by flow cytometry. Moreover, by using Northern blot and Southern blot analyses, this finding was confirmed at the molecular level in GEJ and in murine thyroid epithelial cell cultures, respectively. The functional role of phenothiazine-, de novo-induced MHC class II Ags on thyroid cells was assessed by both syngeneic murine thyroglobulin-specific and allogeneic proliferative T cell responses. These results suggest that antidepressant drugs of the phenothiazine type could play a role in the induction and the perpetuation of thyroid autoimmune disorders, through induction of class II restriction elements on normally class II-negative thyroid epithelial cells.

Effects of calmodulin antagonists on radiation-induced lipid peroxidation in microsomes.

Rat liver microsomes were irradiated with gamma-rays at a dose rate of 1.31 Gys-1. The extent of lipid peroxidation, measured in terms of malondialdehyde (MDA) formed, increased with radiation dose. The presence of calmodulin antagonists during irradiation decreased lipid peroxidation. The order of their protective efficiency was: chlorpromazine (CPZ) greater than promethazine (PMZ) greater than trimeprazine (TMZ). Their protective effect was diminished in the presence of ferrous (Fe2+) ions and was restored on addition of EDTA. However, calmodulin antagonists considerably inhibited radiation-induced lipid peroxidation in the presence of ferric (Fe3+) ions. Calmodulin antagonists also decreased the cytochrome P-450 content of microsomes. These results are discussed with respect to their applicability to radiotherapy. A possible mechanism for the inhibition of radiation-induced lipid peroxidation is suggested.

Modification of radiation induced lipid peroxidation by calmodulin antagonists.

It has been shown that calmodulin antagonists provide radio-protection in euoxic and sensitization in hypoxic conditions. This differential protection in euoxic conditions might have arisen from the interaction of calmodulin antagonists with oxygen free radicals. This possibility has been tested in the present communication. Radiation induced lipid peroxidation process in liposomes has been used for this purpose. Liposomes prepared from L-alpha-lecithin were irradiated with or without calmodulin antagonists. Calmodulin antagonists inhibited lipid peroxidation significantly. The inhibition was found to increase with increase in concentration of the drugs. These observations suggest that calmodulin antagonists have a capacity to scavenge oxygen free radicals involved in initiation and/or propagation of lipid peroxidation process. This may be the reason for their differential radioprotection in euoxic conditions in biological systems.

Cardiovascular and respiratory effects of oral premedication with trimeprazine and droperidol in children.

The systolic blood pressure, pulse rate and respiratory rate were assessed in 112 children before and after receiving premedication consisting of trimeprazine (3 mg/kg) and droperidol (0.2 mg/kg) by mouth. A mild (10%) drop in blood pressure was shown, but no statistical difference was found in the other parameters measured. The premedication is highly efficacious, 70% of patients being asleep in the preanaesthetic room; 27% were calm and only 3% were distressed or crying.

Comparison of temazepam elixir and trimeprazine syrup as oral premedication in children undergoing tonsillectomy and associated procedures.

Temazepam 0.5, 1.0 and 1.5 mg kg-1 in an elixir formulation (Euhypnos Elixir), was compared with trimeprazine tartrate 3 mg kg-1 in a syrup (Vallergan Forte Syrup), as premedication in 220 children (ASA grade I) undergoing tonsillectomy and associated procedures. Each patient was randomly allocated to one of the four treatments. The administration was blind to the observers in theatre, recovery room and postoperative ward, who assessed each patient according to a total of 14 criteria. A modelling technique allowed account to be taken of the effects of concomitant variables (e.g. age and duration of anaesthesia) where appropriate. No statistically significant difference was found between the efficacy of the treatments. The only statistically significant differences were that temazepam was associated with more ectopic beats under anaesthesia (P = 0.03 or 0.002, depending on the test applied), more postoperative vomiting (P = 0.04) and more postoperative restlessness (P less than 0.0001).

Temazepam and trimeprazine compared with placebo as premedication in children. An investigation extended into the first 2 weeks at home.

Temazepam, trimeprazine and placebo were compared as premedication in 85 children undergoing routine otolaryngological operations. Premedication with trimeprazine caused significantly more sedation than temazepam or placebo in patients on arrival in the anaesthetic room (P less than 0.02). Recovery time was significantly longer after trimeprazine than temazepam or placebo (P less than 0.012). Significantly more children (P less than 0.05) failed to recall a picture shown immediately before induction after trimeprazine and temazepam than with placebo. Fewer patients vomited after operation with trimeprazine than with temazepam or placebo (P less than 0.01). The majority of children exhibited some behavioural problem during the first 2 weeks at home, although this rarely lasted for more than a few days. More children exhibited apathetic/withdrawn behaviour after receiving placebo (P less than 0.05), although the significance of this should be interpreted with caution.

Radioprotection of euoxic bacteria by phenothiazine drugs.

Survival studies on irradiated euoxic E. coli B/r cells in presence of various concentrations of four radioprotecting phenothiazine drugs have been carried out. Maximum radioprotection was obtained at a optimal concentration for each drug and it decreased on either side of it. The DNA strand break studies at the maximum protective and non-protective concentrations of chlorpromazine and promethazine revealed that the number of ssbs in DNA were less at the protective concentration which were efficiently repaired by the type-III repair process. On the other hand, at the non-protective concentrations, inhibition of DNA repair was noticed and a higher number of DNA ssbs were detected. We suggest that the membrane is fluidized to a greater extent at the protective concentrations allowing the chemical restitution of damaged sites by NPSH compounds. At the non-protective high concentrations of the drugs, the membrane may be too grossly disorganised to allow any repair and at the same time high concentrations of the drugs or their radicals may also react with radioprotective intracellular sulphhydryls.

Modification of radiation response of E. coli B/r cells by phenothiazines.

Promethazine and trimeprazine sensitized anoxic E. coli B/r cells to 60Co gamma-rays, but both drugs showed a radioprotective effect under euoxic conditions. Their radiosensitizing effect was found to be due to the reaction of radiolytically induced hydroxyl radicals with the sensitizers. The radioprotective effect of these drugs is attributed to changes in the membrane structure conducive with chemical repair of the damaged sites in the gel region of the cellular membrane by intracellular sulphydryl compounds. Pre-irradiation depletion of sulphydryls from E. coli B/r by treatment with N-ethyl maleimide abolished the radio-protective effect of these drugs under euoxic conditions.

Lorazepam in children. A double-blind trial comparing lorazepam, diazepam, trimeprazine and placebo.

One hundred patients aged 5-13 yr were randomly allocated to four groups in a double-blind study of premedication. Drugs studied were lorazepam, diazepam and trimeprazine. A placebo group was included. All the drugs appeared satisfactory as premedicants. Lorazepam induced the most sedation immediately after surgery, but by 4 h lorazepam and diazepam appeared similar. Lorazepam produced better amnesia than the other drugs. There were no untoward side-effects and no cardiorespiratory depression in any group. Lorazepam appears a suitable premedicant for children.

Comparative study of lorazepam and trimeprazine for oral premedication in paediatric anaesthesia.

One hundred and ninety-nine children received lorazepam 0.05 mg kg-1 or trimeprazine 3 mg kg-1 as oral premedication in a double-blind trial. Lorazepam proved more palatable and produced a cheerful demeanour, but possessed no significant advantages on overall assessment before surgery. Following operation, restlessness with vomiting, and evidence of retrograde amnesia occurred more frequently with lorazepam.

Premedication of children with trimeprazine tartrate.

A double-blind trial was undertaken to compare the effects of trimeprazine tartrate (2 mg kg-1 or 4 mg kg-1) plus atropine 0.03 mg kg-1 for oral premedication of 192 children undergoing tonsillectomy. Demeanour before operation, side-effects after operation, recovery times and fluid balance were studied. Behaviour in the anaesthetic room and restlessness after operation were unaffected by the dose given. There was less vomiting associated with 4 mg kg-1 compared with 2 mg kg-1. Prolonged recovery times occurred frequently in the two groups, 14% in the small- and 17% in the large-dose groups taking more than 10 h to recover full mental faculties. Fluid balance was unaffected by the dose and prolonged recovery did not result in a reduction of urine output. Trimeprazine tartrate is not recommended for routine premedication when early recovery is required.

Effects of trimeprazine and trimipramine on nocturnal scratching in patients with atopic eczema.

Twelve men with severe and long-standing atopic eczema were admitted to a double-blind trial to establish the effects of trimeprazine tartrate, trimipramine maleate, and placebo on nocturnal scratching. Neither of the drugs altered the likelihood of a scratching bout beginning in wakefulness or in any stage of sleep. However, both drugs, especially trimipramine, made sleep less broken, and the reduced time spent in stage 1 of sleep accounted for a modest reduction in the overall amount of scratching during the night.