No effect of MDR1 C3435T variant on loperamide disposition and central nervous system effects

BACKGROUND: The MDR1 gene encodes the efflux transporter P-glycoprotein, which is highly expressed in the small intestine and in the blood-brain barrier. A major function of P-glycoprotein is to limit the absorption and central nervous system exposure of numerous xenobiotics. A genetic polymorphism in the MDR1 gene (C3435T) has been associated with changes in the intestinal expression level and function of P-glycoprotein. The aim of this study was to investigate the effect of this polymorphism on disposition and brain entry of the P-glycoprotein substrate loperamide. METHODS: Healthy white volunteers were genotyped for the MDR1 C3435T polymorphism, and a 16-mg oral dose of loperamide was administered to 8 subjects with the 3435TT genotype and 8 subjects with the 3435CC genotype. Plasma levels of loperamide were determined by liquid chromatography-tandem mass spectrometry. Loperamide-induced respiratory depression was detected as the ventilatory response to carbon dioxide and was used as a measure of central nervous system side effects. RESULTS: We found no significant difference in loperamide pharmacokinetics between individuals homozygous for the C and the T alleles in position 3435 of MDR1, as follows: peak plasma drug concentration, 3164 +/- 1053 pg/mL and 3021 +/- 984 pg/mL; area under the concentration-time curve from 0 to 8 hours, 14414 +/- 4756 pg. h/mL and 14923 +/- 6466 pg. h/mL; and time to peak plasma drug concentration, 3.9 +/- 1.4 hours and 3.9 +/- 2.6 hours for the MDR1 3435CC and 3435TT genotypes, respectively (P >.05, for all parameters). Hypercapnic ventilatory response changed only minimally after ingestion of loperamide (the coefficient of variation during the 0- to 8-hour period was 21% +/- 14% for the sample population), and there was no MDR1 3435 genotype-related effect on respiratory response. Carriers of the 2 major MDR1 haplotypes, MDR1*1 and MDR1*13, did not differ in their response to loperamide. CONCLUSION: There was no association between the MDR1 C3435T variation and plasma levels or central nervous system effects of the P-glycoprotein substrate loperamide in a white study population. The MDR1 haplotype structure was quite variable and supports the use of haplotypes instead of single nucleotide polymorphisms in determining clinical consequences of genetic variation.     

Facial appearance in persistent hyperinsulinemic hypoglycemia

Persistent hyperinsulinism is the most common cause of recurrent hypoglycemia in infancy because of inappropriate oversecretion of insulin by the pancreas. Pancreatic lesions can be either focal or diffuse, and they have distinct molecular bases. We have studied the facial features in 17 unrelated patients presenting with neonatal (n = 8) or infancy-onset (n = 9) hyperinsulinism. Hyperinsulinism was related to focal adenomatous hyperplasia (n = 7), diffuse hyperinsulinism (n = 5), non-operated hyperinsulinism (n = 2), and hyperinsulinism with hyperammonemia (n = 3). SUR1 or Kir6.2 mutations were found in six of seven focal adenomatous hyperplasia and three of five diffuse hyperinsulinism. A loss of the maternal allele from chromosome 11p15 in the lesion was found in all focal adenomatous hyperplasia. GLUD1 mutations were found in all patients with hyperammonemia. Large birth weight (mean > 3,800 g) was consistently observed (11/17) but protruding tongue, exomphalos, or visceromegaly were never noted and Wiedemann-Beckwith syndrome could always be ruled out. All patients presented with high forehead, small nasal tip, and short columella giving the impression that the nose is large and bulbous, smooth philtrum, and thin upper lip. A square appearance to the face was more obvious in younger patients. These specific facial features, observed in patients with hyperinsulinism of various molecular mechanisms, could be the consequence of fetal intoxication by insulin. However, to date, facial anomalies have not been noted in infants of diabetic mothers and inversely, malformations that are commonly reported in infants of diabetic mothers were not present in our hyperinsulinemic patients.     

Increased expression of metabotropic glutamate receptor subtype 1 on spinothalamic tract neurons following spinal cord injury in the rat

Spinal cord injury (SCI) leads to an increase in metabotropic glutamate receptor subtype 1 (mGluR1) immunoreactivity in the peri-lesion area. The increased expression of mGluR1 parallels the development of thermal hyperalgesia and mechanical allodynia and has been suggested to contribute to the development and maintenance of chronic central pain (CCP) syndromes resulting from SCI. However, expression of mGluR1 has not been directly shown to increase on cells in the pain pathway. Therefore, the expression of mGluR1 on spinothalamic tract (STT) neurons was quantified using confocal imaging and densiometric analysis in normal, sham, and SCI rats. Contusion SCI produced an increase in mGluR1 expression on STT cells in both the cervical enlargement and the spinal section just rostral to contusion SCI. These results suggest that mGluR1 is expressed on neurons that modulate pain transmission and expression on these cells increases following injury, supporting the hypothesis that mGluR1 contributes to CCP following SCI.     

Focusing on local health needs and promoting new partnerships

Government reports have stressed the importance of community-based interventions in addressing health inequalities. This article discusses the pivotal role played by a health visitor and school nurse team in identifying the health needs of a local community and working in partnership with local people, key community groups, health and youth workers to address these specific needs. A health needs assessment highlighted the need for a parenting programme to support parents in managing young children's behaviour, a forum for teenagers to socialize and access pertinent health information and health days to raise public awareness of key community health issues. To date the parenting programme and the youth club have been implemented. Evaluation has considered how accessible, appropriate, efficient and effective they have been and the knowledge and skills gained by participants. This community development demonstrates how health promotion works through effective community action.     

Generic carbamazepine-induced subacute adrenal insufficiency?

Iatrogenic causes of adrenal insufficiency in Addison's disease are exceptional. We report the case of a patient with a history of epilepsy (taking carbamazepine, Tégrétol LP) and Addison's disease (treated by hydrocortisone (HDC) 30 mg/d, Dectancyl 0,5 mg/d, Florinef 50 mg/d). Recent digestive disorders required emergency hospitalization. The physical examination was normal and laboratory tests showed hyponatremia, hyperkalemia, and elevated serum ACTH. The course was rapidly favorable after rehydration and up-titration of the drug regimen. No triggering factor was identified, but the Tégrétol LP had been replaced for 3 months by a generic drug with the same quantity of active ingredients and the same bioavailability, but with a different excipient (the generic drug was not encapsulated). Could these differences have increased the serum level of carbamazepine and lead to more rapide HDC metabolism by enzymatic induction? Could poorer digestive tolerance have decreased HDC absorption? The hypothesis of carbamazepine overdosage is unlikely because the assay remained within the therapeutic range and hyperkaliemia would favor adrenal decompensation. In conclusion, this single case cannot prove drug interaction but does point out the importance of being prudent when modifying a well--tolerated regimen in a patient with Addison's disease.     

Isolation of differentially expressed genes in NPM-ALK-positive anaplastic large cell lymphoma

In this study, we used subtractive suppression hybridization to compare gene expression between an ALK-positive anaplastic large cell lymphoma (ALCL)-derived cell line and a clinical case of ALK-negative ALCL. Construction and screening of a subtracted library resulted in the cloning of 29 cDNAs which were differentially expressed. Most of these clones corresponded to novel genes with unknown function (EST) or to genes implicated in the differentiation, activation or signalling of T cells such as Ran/TC4, interleukin 1-receptor, thymosin beta4, thymosin beta10, moesin and cytohesin-1. Other genes involved in the regulation of apoptosis, such as human inhibitor of apoptosis-1 (HIAP-1), Bax inhibitor-1 and MCL-1, or DNA repair, such as poly (ADP-ribose) polymerase 1 (PARP-1), X-associated protein-1 (XAP-1), SUMO-1 (sentrin-1) and RanGTPase-activating protein 1 (RanGAP-1), were isolated. Interestingly, we found that both RNA and protein levels of human sterol isomerase (hSI), also referred to as emopamil binding protein (EBP), were overexpressed in ALK+ tumours. This protein is involved in the biosynthesis of cholesterol and may be activated by NPM-ALK. Overall, our results suggest that all the genes described above are upregulated in the NPM-ALK-driven transformation process, and that moesin and cytohesin-1 may be more specifically implicated in a signalling pathway involving PLCgamma and PI3K.     

Predictors of protocol adherence in a pediatric asthma clinical trial

BACKGROUND: Declining protocol adherence can threaten the validity of a clinical trial. OBJECTIVE: We sought to explore patient and family factors important for protocol adherence in the 133 patients followed at one of the 8 Childhood Asthma Management Program (CAMP) clinical centers. Difficulties with timely return of diary cards (diary card problem), with keeping or frequently rescheduling appointments (appointment problem), and with commitment to all aspects of the trial (commitment problem) were tracked prospectively during the treatment phase of CAMP, which ranged from 20 to 40 months at the time of the analysis. METHODS: We performed a cross-sectional analysis. RESULTS: During the course of this investigation, no St Louis CAMP patients dropped out of the study, although signs of eroding participation were observed in 44% of patients. For this cross-sectional analysis, the percentage of patients exhibiting protocol-adherence problems was greater the longer patients had been in the trial: 33.3% at 20 to 25 months, 39.5% at 26 to 30 months, 51.4% at 31 to 35 months, and 69.2% at 36 to 40 months (P <.01). The diary card problem was present in 22.2% of the patients enrolled in the trial for 20 to 25 months compared with 66.7% for patients enrolled for 36 to 40 months (P <.005). Appointment and commitment problems were present in smaller percentages of patients and did not change by time in the trial (P =.41 and.22, respectively). A logistic regression analysis of demographic characteristics indicated that age at randomization and time in the trial were significant factors: for every 2-year increase in age, a child was twice as likely to have a commitment problem (odds ratio [OR], 1.96; 95% CI, 1.50-2.57), and for each additional 5 months of participation in the study, a child was twice as likely to have a diary card problem (OR, 1.91; 95% CI, 1.76-2.07). There was no influence of family income, patient race, or patient sex on the occurrence of any of the 3 protocol-adherence problems. A similar analysis of psychologic characteristics of the child and family indicated (1) a 2-fold increase in the risk of a diary card problem with a 10% increase in the percentage of total commissions on the attention scale of the Gordon Diagnostic Study (OR, 2.18; 95% CI, 2.02-2.35), (2) a 2-fold decrease in the risk of an appointment problem with a 10-unit increase in the Child Manifest Anxiety Scale (OR, 0.46; 95% CI, 0.44-0.49), (3) a 2-fold decrease in risk of an appointment problem with a 10-unit increase in the cohesion subscale of the Family Environment Scale (OR, 0.58; 95% CI, 0.55-0.60), and (4) a 5-fold decrease in the risk of a commitment problem with a 10-unit increase in the Child Depression Index score (OR, 0.21; 95% CI, 0.18-0.24). CONCLUSIONS: Adherence and retention problems commonly occur in longer clinical trials. CAMP patients and families were selected in part on the basis of likelihood of being able to participate in the trial to enhance the conclusions of the trial. Despite this selection process, adherence problems were noted. Problems increased with duration of participation, increasing child age, and the presence of less family cohesion or attention problems in the child. In contrast, the presence of mild emotional distress (anxiety and depression) in the child was associated with fewer protocol-adherence problems. Incorporating procedures that help anticipate and identify adherence problems early might improve continued participation in all aspects of a trial and even retention in long-term clinical trials.     

International variation in histologic grading is large,and persistent feedback does not improve reproducibility

Histologic grading systems are used to guide diagnosis, therapy, and audit on an international basis. The reproducibility of grading systems is usually tested within small groups of pathologists who have previously worked or trained together. This may underestimate the international variation of scoring systems. We therefore evaluated the reproducibility of an established system, the Banff classification of renal allograft pathology, throughout Europe. We also sought to improve reproducibility by providing individual feedback after each of 14 small groups of cases. Kappa values for all features studied were lower than any previously published, confirming that international variation is greater than interobserver variation as previously assessed. A prolonged attempt to improve reproducibility, using numeric or graphical feedback, failed to produce any detectable improvement. We then asked participants to grade selected photographs, to eliminate variation induced by pathologists viewing different areas of the slide. This produced improved kappa values only for some features. Improvement was influenced by the nature of the grade definitions. Definitions based on "area affected" by a process were not improved. The results indicate the danger of basing decisions on grading systems that may be applied very differently in different institutions.