Inhibitory effect of stiripentol on carbamazepine and saquinavir metabolism in human

AIMS

To characterize the in vitro and in vivo inhibitory effect of stiripentol, a new anticonvulsant, on the metabolism of carbamazepine and saquinavir, which are substrates of CYP3A4.

METHODS

Human liver microsomes and cDNA-expressed CYP enzymes were used for the in vitro experiments. Pharmacokinetic data from epileptic children and healthy adults were used for the carbamazepine and saquinavir in vivo studies, respectively.

RESULTS

Carbamazepine biotransformation to its 10,11-epoxide by human liver microsomes (Vmax = 10.3 nmol min(-1) nmol(-1) P450, apparent Km = 362 microm), cDNA-expressed CYP3A4 (Vmax = 1.17 nmol min(-1) nmol(-1) P450, apparent Km = 119 microm) and CYP2C8 (Vmax = 0.669 nmol min(-1) nmol(-1) P450, apparent Km = 757 microm) was inhibited by stiripentol (IC50 14, 5.1, 37 microM and apparent Ki 3.7, 2.5, 35 microm, respectively). Saquinavir biotransformation to its major metabolite M7 by human liver microsomes (Vmax = 5.7 nmol min(-1) nmol(-1) P450, apparent Km = 0.79 microm) was inhibited by stiripentol (IC50 163 microM, apparent Ki 86 microm). In epileptic children treated with carbamazepine and stiripentol, the plasma concentration ratio of carbamazepine epoxide/carbamazepine was decreased by 65%. The in vivo apparent Ki for stiripentol ranged from 10.5 to 41.4 microm. The pharmacokinetics of saquinavir was not modified by stiripentol in healthy adults. The 95% confidence intervals for the difference for Cmax and AUC of saquinavir between the placebo and stiripentol phase were (-39.8, 39.8) and (-33.2, 112), respectively.

CONCLUSIONS

These results showed that stiripentol was a weak inhibitor of saquinavir metabolism both in vitro and in vivo. In contrast, stiripentol is a potent inhibitor of carbamazepine 10,11-epoxide formation in vitro and in vivo in epileptic patients.

Quantitative trait locus detection in commercial broiler lines using candidate regions

A QTL that explained a large proportion of the phenotypic difference between broiler and layer chickens in an experimental cross was evaluated in a commercial broiler line. A three-generation design, consisting of 15 grandsires, 608 half-sib hens, and more than 50,000 third-generation offspring, was implemented within the existing breeding scheme of a broiler breeding company. Four markers from a candidate region on chicken chromosome 4 were selected for their informativeness in the grandsires and used to genotype the first two generations. Using half-sib analyses, linkage was studied between these markers and 13 growth and carcass traits. The QTL analyses confirmed the presence of significant QTL for body weight (P < 0.01) and residual feed intake (P < 0.05) on chicken chromosome 4. Furthermore, evidence was found for QTL affecting the relative weight of bone and muscle in the thigh. Four more markers were added to increase resolution of the QTL positions. This increased the significance of the QTL for body weight (P < 0.001) and residual feed intake (P < 0.01) and showed evidence (P < 0.05) for additional QTL affecting carcass weight and conformation score. This study showed for the first time that a QTL that explains differences between broilers and layers was segregating in lines that have been selected for body weight over 50 generations. A possible explanation could be a pleiotropic or closely linked effect on fitness-related traits that are not part of the present study. The results demonstrate the feasibility of QTL detection and the potential for marker-assisted selection within a commercial broiler line without altering the existing breeding scheme.

[Development of a self-administered questionnaire to assess women's satisfaction with maternity care]

OBJECTIVES

We describe the development and the validation of a French self-administered questionnaire which measures women satisfaction concerning care given during pregnancy. The analysis includes pregnancy monitoring, hospitalization for delivery and homecoming.

METHODS

We considered the content validity, internal-consistency and the reproducibility by test-retest estimates. This survey also compared the characteristics of respondents and non-respondents.

RESULTS

Response rate was 61% and the rate of reply per question was greater than 90%. Eleven dimensions are identified by principal-components analysis. Ten of them had good Cronbach's alpha coefficients (0.58 to 0.83). The convergence between open comments and questions and between the different methods to measure satisfaction was good. The test-retest estimates for each dimension were correct.

CONCLUSION

This questionnaire is reliable. It is a valid tool for evaluation of satisfaction after pregnancy. Designed to be sent to the woman's residence 2 months after childbirth, it can be easily used in common practice.

The use of speech therapy in the treatment of globus pharyngeus patients. A randomised controlled trial

INTRODUCTION

Globus sensation is a common condition accounting for about 4% of new referrals to an ENT clinic. A review of current theories on the cause of globus sensation concludes that no single aetiology is responsible. Wareing et al believed that globus sensation might in part be associated with excessive laryngeal and pharyngeal tension. The aim of this study was to substantiate in a controlled prospective manner the results of a non-controlled study by the same authors that certain speech therapy techniques improved globus symptoms.

METHODS

1. 36 patients with typical globus pharyngeus symptoms were randomised to treatment with speech therapy (Study group) and reassurance by nurse practitioner (Control group). The following data was collated for each patient: duration and type of globus symptoms (sense of a lump in the throat/throat irritation), severity of globus symptoms on a visual analogue scale, fibreoptic laryngoscopy, full blood count, barium swallow. 2. At the end of 3 months, patients in both groups marked on the visual analogue scale the severity of their symptoms.

RESULTS

There was a significant improvement in the globus symptom scores in the speech therapy group compared to pre-intervention scores (p < 0.001, Wilcoxon rank test). There was also a significant improvement in globus symptoms in the speech therapy group compared to controls (p < 0.001, Mann-Whitney U test).

CONCLUSION

Initial results suggest that patients with globus pharyngeus symptoms benefit from speech therapy.

[Long-term efficacy and tolerance of stiripentaol in severe myoclonic epilepsy of infancy (Dravet's syndrome)]

OBJECTIVE

To describe the long term efficacy and tolerance of stiripentol associated with valproate and clobazam in an exhaustive cohort of patients with severe myoclonic epilepsy of infancy (Dravet's syndrome), in which short term efficacy of such a treatment has recently been demonstrated in a placebo-controlled trial.

RESULTS

In 46 patients the frequency and the duration of seizures was significantly reduced (p < 0.001) as well as the number of convulsive status at a median of three-year follow-up. Ten patients were dramatically improved (seizures significantly decreased in number [p = 0.002] and duration [p = 0.002] and status epilepticus disappeared), 20 were moderately improved (seizures significantly decreased in duration [p = 0.001] and status were less numerous), four had no response and efficacy was non evaluable in 12 mainly because of adverse events. Efficacy was better in the youngest patients. The most frequent adverse events were loss of appetite and loss of weight. They could be so severe in patients over 12 years of age that the stiripentol dosage could not be increased to 50 mg kg-1 j-1.

CONCLUSION

This follow-up study shows that stiripentol added to valproate and clobazam maintains its efficacy at long term in children with severe myoclonic epilepsy of infancy and suggests that the tritherapy should be introduced as early as possible in these patients in order to suppress the convulsive status epilepticus.

Remineralization of enamel subsurface lesions by sugar-free chewing gum containing casein phosphopeptide-amorphous calcium phosphate

Casein phosphopeptide-amorphous calcium phosphate nanocomplexes (CPP-ACP) exhibit anticariogenic potential in laboratory, animal, and human in situ experiments. The aim of this study was to determine the ability of CPP-ACP in sugar-free chewing gum to remineralize enamel subsurface lesions in a human in situ model. Thirty subjects in randomized, cross-over, double-blind studies wore removable palatal appliances with six human-enamel half-slabs inset containing sub-surface demineralized lesions. The appliances were inserted immediately before gum-chewing for 20 min and then retained for another 20 min. This was performed four times per day for 14 days. At the completion of each treatment, the enamel half-slabs were paired with their respective demineralized control half-slabs, embedded, sectioned, and subjected to microradiography and densitometric image analysis, for measurement of the level of remineralization. The addition of CPP-ACP to either sorbitol- or xylitol-based gum resulted in a dose-related increase in enamel remineralization, with 0.19, 10.0, 18.8, and 56.4 mg of CPP-ACP producing an increase in enamel remineralization of 9, 63, 102, and 152%, respectively, relative to the control gum, independent of gum weight or type.

An aid to the early detection and management of diabetic nephropathy: assessment of a new point of care microalbuminuria system in the diabetic clinic

AIMS

To compare the performance of the DCA2000 microalbuminuria system for albumin and creatinine concentrations and the albumin:creatinine ratio (ACR) with laboratory measurements in the hospital diabetes clinic and to assess the ease of use and applicability by standard clinic personnel.

METHODS

Urine albumin and creatinine concentration and ACR were measured in 154 diabetic patient samples and in 77 normal subjects. Both albumin assays are based on immunoturbidimetry. The DCA2000 system utilizes reagent cartridges processed automatically.

RESULTS

Control material within-run precision (coefficient of variation (CV)) for albumin and creatinine ranged up to 7.1% and 3.3% respectively. Between-run CVs ranged from 2.1% to 4.3%. Method comparisons yielded correlation coefficients > 0.99 for albumin, creatinine and ACR, only a small negative bias of 3.2 mg/l for albumin and 0.10 mg/mmol for ACR, no concentration-related bias for ACR and no between-method difference for either albumin (P = 0.195) or ACR (P = 0.341). At a laboratory albumin concentration cut-off of 20 mg/l the sensitivity, specificity, negative and positive predictive values were 92.4% 100% 92.7% and 100%. Normal reference range mean albumin, creatinine and ACR values for the DCA2000 and the laboratory were 7.7 mg/l vs. 9.0 mg/l 13.0 mmol/l vs. 12.6 mmol/l and 0.66 mg/mmol vs. 0.81 mg/mmol respectively. Clinic personnel found that the DCA2000 system was easy to use suited the clinic environment and generated confidence in the results.

CONCLUSIONS

This point of care system safely substitutes laboratory-based measurements. Ease of use and low cost make it suitable for screening and monitoring diabetes treatment. It facilitates the use of random urines, and may obviate the need for timed samples. This approach has a clear place in the battle to reduce the diabetic vascular disease burden.

GDEP, a new gene differentially expressed in normal prostate and prostate cancer

BACKGROUND

The database of human expressed sequence tags (dbEST) is a potential source for the identification of tissue specific genes. The database contains sequences that originate from cDNA libraries from different tissues cell types and tumors.

METHODS

Computer based analysis identified a cluster of sequence homologous ESTs, containing ESTs derived only from human prostate cDNA libraries. The tissue specificity was examined by multiple tissue RNA dot blots and RT-PCR. The new RNA transcript was characterized using northern blot analysis, RACE-PCR, and a ribonuclease protection assay.

RESULTS

We have identified a gene differentially expressed in prostate using EST database analysis and experimental studies. We name the gene GDEP for gene differentially expressed in prostate. The major GDEP transcript is about 520 bp long. GDEP RNA was detected in nine prostate tissue samples, four normal and five cancer. Expression in prostate epithelial cells was established by in situ hybridization. Weak expression was detected in the prostate cancer cell line LNCaP. In vitro transcription/translation indicate that the RNA encodes a small 34 amino acid protein. The major transcript consists of two exons with one large intron (> 15 kb). The GDEP gene was mapped to chromosome 4q21.1 by radiation hybrid mapping.

CONCLUSIONS

Our data proves that tissue specific genes can be identified by EST database mining. The prostate specificity of GDEP expression indicates that GDEP may be useful in the diagnosis or treatment of prostate cancer. Published 2001 Wiley-Liss, Inc.

Emergence of tics in children with attention deficit hyperactivity disorder treated with stimulant medications

The emergence of tics in children treated with stimulant medication for attention deficit hyperactivity disorder (ADHD) was investigated. A retrospective chart review of the medical records of 555 subjects was performed to examine the emergence of tics in relation to treatment with a stimulant medication, dosage, duration of treatment, and age of subjects. A total of 7.8% of the subjects treated with stimulants developed tics: 8.3% of subjects treated with methylphenidate, 6.3% with dextroamphetamine, and 7.7% with pemoline. The subjects who developed tics were significantly younger than those who did not. Subjects treated with higher doses of stimulant medication were not more likely to develop tics. While the emergence of tics was common, these subjects may have developed tics irrespective of stimulant medication. Controversy remains as to the long-term risk of tics in relation to stimulant medication and to appropriate practice should tics emerge during the course of stimulant medication treatment.

Pharmacological properties of the mouse neurotensin receptor 3. Maintenance of cell surface receptor during internalization of neurotensin

We recently reported the molecular identification of a new type of receptor for the neuropeptide neurotensin (NT), the neurotensin receptor 3 (NTR3), identical to sortilin, which binds receptor-associated protein. Here, we demonstrate that the cloned mouse NTR3 is expressed on the plasma membrane of transfected COS-7 cells. The mouse NTR3 is detectable by photoaffinity labeling and immunoblotting at the cell surface as a 100 kDa N-glycosylated protein. Biochemical analysis and confocal microscopic imaging clearly indicate that NT is efficiently internalized after binding to NTR3, and that despite this internalization, the amount of receptor present on the cell surface is maintained.

Protective effect of stiripentol on acetaminophen-induced hepatotoxicity in rat

Acetaminophen (APAP) is mainly eliminated at a therapeutic dose through glucuronidation and sulfatation and a small fraction is oxidized by cytochromes P450 (CYP) 2E1, 3A4, and 1A2 to N-acetyl-p-benzoquinone-imine (NAPQI), a highly reactive metabolite further conjugated with glutathione into APAP-GSH, and then metabolized to APAP-cystein and APAP-mercapturate excreted in urine. After APAP overdose, the glucuronidation and sulfatation pathways are saturated and the production of NAPQI increases, causing hepatic injury. Stiripentol (STP); (200 mg/kg), an anticonvulsant drug inhibitor of CYP1A2 and CYP3A4 in vivo in humans was tested against APAP-induced toxicity in rat in comparison with N-acetylcysteine (NAC; 100 mg/kg). The mortality rates 24 h after APAP overdose (2 x 500 mg/kg) were 63% (control), 38% (NAC), 0% (STP), and 4% (STP + NAC). The mean plasma transaminase concentrations 5 and 24 h after overdose were significantly higher in control than in STP and NAC groups. The percentage of rats without microscopic liver necrosis 5 h after APAP overdose was significantly higher in rats receiving STP (100%), NAC (83%), or STP + NAC (83%) than controls (42%). In another experiment, four similar groups were administered 50 mg/kg APAP. Plasma AUC(0-5 h) for APAP-GSH, APAP-cystein, and APAP-mercapturate as well as urine APAP-mercapturate mean amounts were significantly lower in STP animals than in the other groups. STP (200 mg/kg) inhibited NAPQI synthesis through CYP inhibition, thus preventing both liver necrosis and mortality in rats.

Stiripentol in severe myoclonic epilepsy in infancy: a randomised placebo-controlled syndrome-dedicated trial. STICLO study group

BACKGROUND

Stiripentol is an inhibitor of cytochrome P450 that showed antiepileptic efficacy in severe myoclonic epilepsy in infancy (SMEI) in association with clobazam and valproate in an open study. To confirm these results, 41 children with SMEI were included in a randomised, placebo-controlled, add-on trial.

METHODS

After a baseline period of 1 month, placebo (n=20) or stiripentol (n=21) was added to valproate and clobazam during a double-blind period of 2 months. Patients then received stiripentol in an open fashion. Responders were defined as having more than 50% reduction in the frequency of clonic (or tonic-clonic) seizures during the second month of the double-blind period compared with baseline.

FINDINGS

15 (71%) patients were responders on stiripentol (including nine free of clonic or tonic-clonic seizures), whereas there was only one (5%) on placebo (none were seizure free; stiripentol 95% CI 52.1-90.7 vs placebo 0-14.6). The 95% CI of the difference was 42.2-85.7. Percentage of change from baseline was higher on stiripentol (-69%) than on placebo (+7%), p<0.0001. 21 patients on stiripentol had moderate side-effects (drowsiness, loss of appetite) compared with eight on placebo, but side-effects disappeared when the dose of comedication was decreased in 12 of the 21 cases.

INTERPRETATION

This controlled trial shows the antiepileptic efficacy, of add-on stiripentol in children with SMEI. The results also provide good reason to focus studies on a specific epilepsy syndrome-a small sample of patients is sufficient to show the efficacy that might have been missed in a heterogeneous population.

Lack of effect of grapefruit juice on the pharmacokinetics and pharmacodynamics of amlodipine

AIMS

To determine whether repeated once daily administration of grapefruit juice altered the pharmacokinetics or pharmacodynamics of the calcium antagonist amlodipine.

METHOD

S The effects of grapefruit juice on the pharmacokinetics and pharmacodynamics of oral and intravenous amlodipine were assessed in 20 healthy men in a placebo-controlled, open, randomized, four-way crossover study using single doses of amlodipine 10 mg. For 9 days beginning with the day of administration of amlodipine, grapefruit juice (or water control) was given once daily, and blood samples, blood pressure and heart rate measures were obtained. Plasma concentrations of amlodipine and its enantiomers were determined in separate assays by GC-ECD.

RESULTS

Oral amlodipine had high systemic availability (grapefruit juice: 88%; water: 81%). Pharmacokinetic parameters of racemic amlodipine (AUC, Cmax, tmax, and kel) were not markedly changed with grapefruit juice coadministration. Total plasma clearance and volume of distribution, calculated after intravenous amlodipine, were essentially unchanged by grapefruit juice (CL 6.65 ml min-1 kg-1, juice vs 6.93 ml min-1 kg-1, water; Vdss 22.7 l kg-1, juice vs 21.0 l kg-1, water). Grapefruit juice coadministration did not greatly alter the stereoselectivity in amlodipine oral or intravenous kinetics. The sum of S(-) and R(+) enantiomer concentrations correlated well with total racemic amlodipine concentration (r2 = 0. 957; P = 0.0001). Coadministration of grapefruit juice with either route of amlodipine administration did not significantly alter blood pressure changes vs control.

CONCLUSIONS

Grapefruit juice has no appreciable effect on amlodipine pharmacodynamics or pharmacokinetics, including its stereoselective kinetics. Bioavailability enhancement by grapefruit juice, noted with other dihydropyridine calcium antagonists, does not occur with amlodipine. Once daily grapefruit juice administration with usual oral doses of amlodipine is unlikely to alter the profile of response in clinical practice.

The effects of intracoronary brachytherapy on the natural history of postangioplasty dissections

OBJECTIVES

The aim of this study was to determine the natural history of postangioplasty intravascular ultrasound (IVUS)-detected dissections and to assess the influence of intracoronary beta-radiation on dissection resolution.

BACKGROUND

Intracoronary radiotherapy is considered to impair exaggerated vessel healing. Conversely, excessive healing impairment may increase the risk of complications due to unhealed dissection. Alternatively, residual dissection may represent an innocent marker of adequate therapy.

METHODS

Immediate postangioplasty and six-month follow-up IVUS studies of 94 patients in the IVUS substudy of the MultiVitamins and Probucol (MVP) trial and 26 nonstented patients in the Beta Energy Restenosis Trial (BERT) were analyzed for the presence or absence of dissection.

RESULTS

Of the 28 patients with postangioplasty dissections in MVP, only one had evidence of residual dissection at six months (95% confidence interval [CI] for failure rate 0.2%; 20.2%). Conversely, 9 of 16 dissections had healed in BERT (95% CI for failure rate 30.6%; 79.2%) (p < 0.0002). Nevertheless, an index based on dissection arc and length demonstrated improvement in the irradiated patients. Irradiated patients with residual dissections showed significant increase in lumen area at six-months (5.10 +/- 0.98 to 7.11 +/- 2.61 mm2, p < 0.02) not noted when there was resolution of the dissection (6.03 +/- 2.38 to 6.36 +/- 3.33 mm2, p = NS). In both groups the external elastic membrane area was unchanged at follow-up.

CONCLUSIONS

Resolution appears to be the natural history of IVUS-detected dissections in most cases. Significant resolution of dissection occurs following intracoronary beta-radiation as reflected in reduced dissection index at six-months in these patients, although significant impairment of vessel wall healing was noted.

Allelic distribution of CTG18.1 in Caucasian populations: association studies in bipolar disorder, schizophrenia, and ataxia

CTG18.1 is a highly polymorphic and unstable CTG repeat within an intron of the SEF2-1 gene. We tested the CTG18.1 repeat length in affective disorder, schizophrenia, and nonspecific ataxia; these diseases all have shown clinical evidence for anticipation. There was no difference in the allele frequencies comparing the controls and disease groups. The most common allele contains 11 CAGs (35%) followed by alleles with 14-17 CAGs (35%). There was no difference in the distribution of the alleles in the cases vs controls for ataxia (P = 0.11), affective disorders (P = 0.21), or schizophrenia (P = 0.26). The frequency of unstable CTG18.1 alleles was approximately 3% in a population of N. European descent and is not related to the phenotypes tested.