The Delta>15 Kb deletion French Canadian founder mutation in familial hypercholesterolemia: rapid polymerase chain reaction-based diagnostic assay and prevalence in Quebec

Approximately one in 500 individuals in Western population has autosomal dominant familial hypercholesterolemia due to mutations in the low-density lipoprotein receptor (LDLR) gene. Screening for these mutations is hampered by their large number, except in founder populations. We identified the breakpoint of the >15 kb deletion involving the LDLR gene promoter and exon 1, responsible for more than 60% of French Canadian hypercholesterolemia cases, as well as the breakpoint of the 5 kb deletion of exons 2 and 3 that accounts for an additional 5% of cases. Both deletions appear to be because of homologous recombination by unequal crossing-over between the left arms of Alu repeats. Using RepeatMasker, we determined that 55% of the LDLR gene is composed of Alu elements; thus, it is not surprising that most LDLR rearrangements involve at least one Alu. Furthermore, we developed a rapid polymerase chain reaction-based assay for the French Canadian-1 (>15 kb) and French Canadian-5 (5 kb) hypercholesterolemia alleles. Screening a representative population sample of 943 French Canadian youths whose LDL cholesterol levels were above the 50th percentile allowed us to estimate the prevalence of the >15 kb allele as 0.11% (95% confidence interval, 0.03-0.38).

Severe hypophosphatemia in a patient with anorexia nervosa during enteral refeeding

Hypophosphatemia is a seldom but potentially fatal complication of the nutritional recovery or refeeding syndrome in patients with protein-calorie malnutrition or starvation. We report here the case of a 35-year-old anorexic patient who presented a severe but uncomplicated hypophosphatemia during enteral refeeding, despite phosphorus supplementation. Serum phosphorus monitoring is recommended in severely malnourished anorexic patients, particularly during the first week of refeeding, be it parenteral or enteral.

Insulin resistance syndrome in a representative sample of children and adolescents from Quebec, Canada

OBJECTIVES

To estimate the prevalence of insulin resistance syndrome (IRS) in a representative sample of youth. To test for the independent contribution of insulin resistance (IR) and adiposity to clustering of metabolic risk factors. To identify the underlying components of IRS. To examine the relationship between adiposity and fasting plasma levels of free fatty acids (FFA).

METHODS

In 1999, we conducted a school-based survey of a representative sample of youth aged 9, 13 and 16 y in Quebec, Canada. Age-specific questionnaire data, standardized clinical measurements and a fasting blood sample were available for 2244 subjects. Fasting insulin and HOMA were used as surrogate measures of IR.

RESULTS

In all age-sex groups, adiposity indices, blood pressure (BP), plasma glucose and triglycerides (TG) increased significantly with increasing insulin quartiles while HDL cholesterol (HDL-C) decreased. The overall prevalence of IRS defined as hyperinsulinaemia combined with two or more risk factors including overweight, high systolic BP, impaired fasting glucose, high TG and low HDL-C, was 11.5% (95% CI: 10.2-12.9). There were no significant differences in the prevalence of IRS across ages or between sexes. The independent contribution of adiposity to clustering of risk factors was stronger than that of fasting insulin (or HOMA-IR). Factor analysis revealed three factors (BMI/insulin/lipids, BMI/insulin/glucose and diastolic/systolic BP) consistent across ages suggesting that more than one pathophysiologic process underlies IRS. Although elevation of FFA might be in the causal pathway linking obesity to IR, we did not detect any consistent association between measures of fatness and fasting plasma FFA.

CONCLUSION

IRS is highly prevalent in youth, even among children as young as age 9 y. Factor analysis identifies three physiologic domains within IRS with a unifying role for markers of IR and adiposity.

[Atypical antipsychotics in therapy refractory schizophrenia]

Many studies have shown that treatment resistance is a substantial problem in schizophrenic patients, with 20-30% of patients responding only partially and about 7% showing no response to antipsychotic treatment. Clozapine has been consistently shown to be effective in this subgroup of schizophrenic patients. It is still the drug of choice, despite the restricted indication and the need for a careful evaluation of side effects. Recently, several double-blind studies of newer atypical antipsychotics have been conducted in therapy-resistant patients. Three studies compared risperidone with clozapine, one study zotepine with clozapine and two others olanzapine with dozapine. One study compared the efficacy of clozapine, olanzapine, risperidone with one another and with haloperidol. In these studies, dozapine showed increasing superiority the more restrictive the criteria for therapy-resistance chosen. Olanzapine was found to be as effective as clozapine and was better tolerated. However, the results of studies comparing different atypical anti-psychotics have to be interpreted carefully because of their limited number as well as methodological problems. Case studies also indicate the efficacy of combining different atypical antipsychotics, but no systematic research on this issue has been done so far.

[Prolonged asystole after spinal anesthesia in a patient with Gallavardin's syndrome]

A clinical case of spontaneous ventricular dysrythmia in a 47-year-old patient scheduled for ankle osteosynthesis is reported. During initial peripheral vein canulation, a spontaneous ventricular tachycardia occurred and disappeared spontaneously in about 3 min. It was decided to proceed with surgery. Thirty minutes after spinal anaesthesia, asystole occurred. Normal sinus rhythm was rapidly restored after basic life support. There was no harmful consequence for the patient. He had a history of repetitive monomorphic ventricular tachycardia (Gallavardin type). The aetiologies of asystole after spinal anaesthesia are well known and will be not discussed in the text. Although the origin of the asystole is unclear in this case, the literature on Gallavardin's syndrome is reviewed, showing that a prolonged and complex preoperative assessment is not mandatory in this syndrome.

Lack of gender effect on the pharmacokinetics and pharmacodynamics of dexamethasone in the camel after intravenous administration

The pharmacokinetics and pharmacodynamics of dexamethasone were studied in six male and six female camels after a single intravenous dose (0.05 mgkg(-1) body weight) of dexamethasone. The pharmacokinetic parameters of the two-compartment pharmacokinetic model for female and male camels, respectively (mean+/-SEM) were as follows: terminal elimination half-lives were 8.02+/-1.15 and 7.33+/-0.80 h, total body clearances were 95.5+/-16.0 and 124.5+/-11.9 ml h(-1) per kg, volumes of distribution at steady state were 0.72+/-0.08 and 0.87+/-0.14 litre kg(-1), and the volumes of the central compartment were 0.12+/-0.02 and 0.17+/-0.02 litre kg(-1). There was no significant difference in any pharmacokinetic parameter between female and male camels. Pharmacodynamic effects were evaluated by measuring endogenous plasma cortisol, circulating lymphocytes and neutrophils numbers and were analysed using indirect pharmacokinetic/pharmacodynamic models. The estimated IC50 of dexamethasone for cortisol and lymphocytes for female and male camels were 3.74+/-0.99 and 2.28+/-1.09 and 2.63+/-0.71 and 2.41+/-0.79 ng ml(-1), respectively. The EC50 for neutrophils for female and male camels were 24.5+/-5.83 and 20.2+/-3.82 ng ml(-1), respectively. There was no significant difference in any pharmacodynamic parameter between female and male camels. Dexamethasone in urine could be detected for 4-5 days by enzyme-linked immunosorbent assay and for 3-4 days by liquid chromatography/mass spectrometry after an intravenous dose of 0.05 mg kg(-1) body weight.

Pharmacokinetics and Pharmacodynamics of Dexamethasone after Intravenous Administration in Camels: Effect of Dose

The pharmacokinetics and pharmacodynamics of dexamethasone were evaluated in healthy camels after single intravenous bolus doses of 0.05, 0.1 and 0.2 mg/kg body weight. Dexamethasone showed dose-independent pharmacokinetics. The pharmacokinetic parameters of the two-compartment pharmacokinetic model for the lowest intravenous dose (mean+/-SD) were as follows: terminal elimination half-life 8.17 +/- 1.79 h; total body clearance 100.7 +/- 52.1 (ml/h)/kg; volume of distribution at steady state 0.95 +/- 0.23 L/kg; and volume of the central compartment 0.22 +/- 0.07 L/kg. The extent of plasma protein binding was linear over the concentration range 5-100 ng/ml and averaged 75% +/- 2%. Pharmacodynamic effects were evaluated by measuring endogenous plasma cortisol concentrations, numbers of circulating lymphocytes and neutrophils and plasma glucose concentrations and were analysed using indirect pharmacokinetic/pharmacodynamic models. The cumulative systemic effect increased with dose for markers of pharmacodynamic activity. The estimated IC50 of dexamethasone for cortisol and lymphocytes for the lowest dose were 3.74 +/- 2.44 and 5.58 +/- 8.37 ng/ml, respectively and the EC50 values for neutrophils and glucose were 45.8 +/- 36.9 and 1.17 +/- 0.71 ng/ml, respectively.

N-cadherin activation substitutes for the cell contact control in cell cycle arrest and myogenic differentiation: involvement of p120 and beta-catenin

N-cadherin is expressed throughout skeletal myogenesis and has been proposed to be involved in the differentiation program of myogenic precursors. Here, we further characterize the N-cadherin involvement and its mechanism of action at the onset of differentiation, through controlled N-cadherin activation by plating isolated C2 myoblasts on surfaces coated with a chimeric Ncad-Fc homophilic ligand (N-cadherin ectodomain fused to the immunoglobulin G Fc fragment). We show that N-cadherin activation substitutes for the cell density in myogenic differentiation by promoting myogenin and troponin T expression. In addition, N-cadherin adhesion participates to the associated cell cycle arrest through the nuclear accumulation of cyclin-dependent kinase inhibitors p21 and p27. Mouse primary myoblast cultures exhibited similar responses to N-cadherin as C2 cells. RNA interference knockdowns of the N-cadherin-associated cytoplasmic proteins p120 and beta-catenin produced opposite effects on the differentiation pathway. p120 silencing resulted in a decreased myogenic differentiation, associated with a reduction in cadherin-catenin content, which may explain its action on myogenic differentiation. beta-Catenin silencing led to a stimulatory effect on myogenin expression, without any effect on cell cycle. Our results demonstrate that N-cadherin adhesion may account for cell-cell contact-dependent cell cycle arrest and differentiation of myogenic cells, involving regulation through p120 and beta-catenins.

MR imaging findings in a patient with hepatic veno-occlusive disease

We report the MRI findings in a 31-year-old woman with veno-occlusive disease. MRI demonstrated patent hepatic veins and patchy signal enhancement of the liver after gadolinium chelate injection. This enhancement was compatible with sinusoidal congestion. The diagnosis of veno-occlusive disease was confirmed by histological examination of liver biopsy. The diagnosis of veno-occlusive disease should be evoked when patchy liver enhancement suggestive of sinusoidal congestion is observed in the absence of hepatic vein thrombosis and congestive heart failure.

Polymyosites induites ou associées aux traitements hypolipémiants ?

PURPOSE

Rhabdomyolysis and myositis are rare, dose-related complications of statins and fenofibrates. The outcome is favorable as a rule with rapid regression after stopping the responsible drug. Recently, various auto-immune disease with evidence of hypersensitivity to HMG-CoA reductase inhibitors or fibrates drugs have been reported. Less than ten cases of dermatomyositis and polymyositis due to cholesterol-lowering drugs (CLD) have been previously reported. Five more cases polymyositis associated with CLD are reported.

METHODS

Symptoms were compatible with diagnosis of polymyositis according to Bohan and Peter and with previous reported criteria for drug-induced myopathy in all cases. None of these patients had previous other connective tissue disorders.

RESULTS

Five patients (median age 68 [54-78], female N =4) with CLD treatment (statin N =4, fenofibrates N =1) have developed iatrogenic polymyositis. All of them presented both proximal muscular weakness and increased muscle enzyme levels. One patient had iatrogenic antisynthetase syndrome characterized by mechanic's hand, Raynaud's phenomenon and anti JO1 antibodies. One other had sclerodermic hand oedema. Antinuclear antibodies were positive in 4 cases and muscle biopsy revealed polymyositis infiltrate in 4 cases. CLD treatment was discontinued with partial clinical improvement in 3 cases. Clinical remission was obtained with corticosteroid (N =5) in association with immunosuppresive agents in 3 cases.

CONCLUSION

Muscular symptoms in patient with CLD treatment could be the first symptom of a polymyositis revealed or increased by this treatment and must encourage physician with antinuclear antibodies screening especially in case of proximal muscular weakness and increased muscle enzyme levels.

Subjective well-being and initial dysphoric reaction under antipsychotic drugs - concepts, measurement and clinical relevance

Since the introduction of neuroleptics in 1952, many studies have examined objective aspects of efficacy and tolerability. Despite the fact that neuroleptic treatment should also improve the patient's subjective experiences, this outcome criterion has been neglected in the past. This is unfortunate, as subjective well-being with treatment appears to be strongly related to patients' readiness to take their medication. The few existing studies differ in methodology and are difficult to compare due to a number of weaknesses, including varying underlying concepts, used assessment scales, or small sample sizes. Negative subjective well-being may manifest itself throughout the entire neuroleptic treatment, even as early as in the first 48 hours after neuroleptic treatment starts (initial dysphoric reaction, IDR). The aetiology of reduced subjective well-being or IDR is not fully explained; neuroleptic side effects, especially affective, cognitive and motor adverse events, differential effects of varying psychopathology or biopsychosocial are factors in discussion. The clinical impression is characterised by symptoms as dysphoria/anhedonia, reduced vitality, and emotional indifference, which could have a negative impact on relevant clinical factors such as response or medication adherence, and therefore on outcome. With regard to pharmacological treatment, evidence suggests that atypical antipsychotics induce less negative subjective effects than conventional neuroleptics, and that various new-generation antipsychotics could be evaluated differently by patients. This article reviews existing literature in order to approach relevant questions for pharmacotherapy.

Étude de l'influence d'une hypergammaglobulinémie sur le titre des anticorps antiphospholipides

PURPOSE

Antiphospholipid antibodies (aPL), anticardiolipin antibodies (aCL) or lupus anticoagulant (LA), are indispensable for the diagnosis of antiphospholipid syndrome (APS). However, antiphospholipid assays can generate false positive results.

MATERIALS

We have studied the influence of hypergammaglobulinemia (HG) on aPL antibodies titers in 232 patients twice as positive for aPL antibodies.

RESULTS

Out of 232 patients, 93 have an APS (76 primary APS, 17 secondary APS). Thrombosis occurred 138 times in APS patients. Of 139 patients without APS, 95 have an auto-immune disease, 28 have an isolated prolonged KCT and 16 an evolutive neoplasia. LA seems to be the best marker of APS. On the other hand aCL IgG and M, anti-beta2-GP1 IgM titers are significantly higher in patients without APS but with HG.

CONCLUSION

Those results suggest that biological APS diagnosis should be carefully performed in patients with HG. In this case, other additional risk factors must be considered for the etiological diagnosis of thrombosis.

Lamellipodium extension and cadherin adhesion: two cell responses to cadherin activation relying on distinct signalling pathways

Cell adhesion molecules of the cadherin family contribute to the regulation of cell shape and fate by mediating strong intercellular adhesion through Ca2+-dependent interaction of their ectodomain and association of their cytoplasmic tail to actin. However, the mechanisms co-ordinating cadherinmediated adhesion with the reorganization of the actin cytoskeleton remain elusive. Here, the formation of de novo contacts was dissected by spreading cells on a highly active N-cadherin homophilic ligand. Cells responded to N-cadherin activation by extending lamellipodium and organizing cadherin-catenin complexes and actin filaments in cadherin adhesions. Lamellipodium protrusion, associated with actin polymerization at the leading edge sustained the extension of cadherin contacts through a phosphoinositide 3-kinase (PI 3-kinase)-Rac1 pathway. Cadherin adhesions were formed by PI 3-kinase-independent, Rac1-dependent co-recruitment of adhesion complexes and actin filaments. The expression and localization of p120 at the plasma membrane, associated with an increase in membrane-associated Rac1 was required for both cell responses, consistent with a major role of p120 in signalling pathways initiated by cadherin activation and contributing to Rac1-dependent contact extension and maturation. These results provide additional information on the mechanisms by which cadherin coordinates adhesion with dynamic changes in the cytoskeleton to control cell shape and intercellular junction organization.

Elevated serum heat-shock protein 70 levels in patients with acute infection: use of an optimized enzyme-linked immunosorbent assay

Heat-shock proteins (Hsps) are highly conserved throughout evolution and evoke great interest both in basic biology and in medicine. They are expressed in small quantities under normal conditions, and their expression can be strongly induced by several stressors. Although their action is basically intracellular, it is now obvious that these proteins can be released into the extracellular environment from viable cells. In this study, the human Hsp 70 serum concentrations were determined using an optimized, cost-effective enzyme-linked immunosorbent assay (ELISA). The average intra-assay variation was 6%, whereas the average interassay variation was 9%. The sensitivity of the assay was 10 ng/ml, and spiking experiments showed recoveries between 101 and 109%. As an application of the technique, we have investigated the serum levels of human Hsp 70 in patients with infection and in healthy subjects. Our data show significantly higher levels of Hsp 70 (P = 0.003) in patients compared to control subjects. Positive correlations were noticed between the serum levels of Hsp 70 and various markers of inflammation (IL-6; r = 0.579, P = 0.009, TNF-alpha; r = 0.552, P = 0.012, IL-10; r = 0.361, P = 0.002). We conclude that Hsp 70 is involved in inflammation of infectious origin. The interindividual variation in the serum concentration of Hsp 70 precludes the use of serum Hsp 70 levels to distinguish patients from healthy subjects.

Die initial dysphorische Reaktion (IDR) auf die Ersteinnahme von Neuroleptika

Initial dysphoric response (IDR) is characterized by a negative affective reaction within 48 h after a neuroleptic test dose. Currently, there are three scales for measuring the IDR (Neuroleptic Dysphoria Scale, Dysphoric Response Index, Drug Attitude Inventory). The debate continues about the definition, measurement, and underlying aetiology of IDR. Nevertheless, with a prevalence of 30%, the response is a clinically relevant phenomenon. Empirical data give some evidence of an association between IDR and short-term outcome. No correlation of IDR with pretreatment variables has been found yet (e.g. age, gender, and psychopathology at baseline, especially depression and hostility). With respect to aetiology, a negative subjective reaction to concurrent extrapyramidal side effects and direct dysaffective effects of some neuroleptics have been discussed. Other studies found that IDR might not be a specifically antipsychotic effect. Our first results give some evidence that patients treated with atypical antipsychotics experience IDR less often and less severely than those treated with conventional antipsychotics described in the literature. Further research should include placebo-controlled studies and the evaluation of specific pretreatment variables. To assess the aetiology of IDR, further basic research is needed.

[Regulation of cell adhesion by the cadherin cytoplasmic domain]

Juxtacrine cell interactions associated to cadherin-mediated cell-cell adhesion play a major role in the organization and homeostasis of tissues. Here, we review the intracellular molecules and regulations controlling the formation of cell-cell contacts initiated by homophilic interactions of cadherin ectodomain. These regulations involve proteins associated to cadherin cytoplasmic tail, named catenins, their association to the actin cytoskeleton and the stability of these complexes at the cell membrane. The underlying molecular mechanisms, which participate in the formation of dynamic cell-cell contacts, are intensively investigated.

Both Insulin Resistance and Diabetes inPsammomys obesusUpregulate the Hepatic Machinery Involved in Intracellular VLDL Assembly

OBJECTIVE

In the current study, we examined the mechanisms that regulate hepatic apolipoprotein B (apoB)-containing lipoprotein secretion in Psammomys obesus, a good animal model for the investigation of insulin resistance and diabetes.

METHODS AND RESULTS

When fed chow ad libitum, 22% maintained normoglycemia and normoinsulinemia (group A), 33% exhibited normoglycemia and appreciable hyperinsulinemia (group B), and 45% developed overt diabetes (group C). Body weight gain, plasma free fatty acid elevation, hypertriglyceridemia, and hypercholesterolemia characterized groups B and C. Triton WR-1339 injection, at fasting, resulted in higher plasma VLDL-triglyceride and VLDL-apoB accumulation in groups B and C, suggesting increased VLDL production by the liver. Pulse-chase labeling experiments in cultured hepatocytes with [35S]methionine revealed reduced intracellular degradation and enhanced secretion of newly synthesized apoB in groups B and C. Concomitant with the raised triglyceride and cholesterol contents in the livers of groups B and C, there was an increase in lipogenesis and in the activity of microsomal triglyceride transfer protein, monoacylglycerol acyltransferase, and diacylglycerol transferase. Pretreatment of hepatocytes with proteasomal inhibitors eliminated the differences in apoB secretion among groups A, B, and C.

CONCLUSIONS

Our data indicate that both insulin resistance and diabetes triggered the intracellular machinery involved in VLDL assembly and secretion.

[Patient compliance with drug therapy in temporal arteritis]

OBJECTIVE

To evaluate patient compliance with drug therapy in temporal arteritis and to determine the characteristics of compliant or non-compliant patients.

METHODS

Inpatients and outpatients from an Internal Medicine Unit were interviewed. Compliance with drug dosage and administration time was assessed with a questionnaire for the following drugs: glucocorticoids, calcium, vitamin D, diphosphonates (prevention of glucocorticoid-induced osteoporosis).

RESULTS

Forty-nine patients were interviewed (61% female, mean age = 73.7 years). Glucocorticoids were prescribed to 96% of the patients, calcium and vitamin D to 86% and diphosphonates to 49%. Compliance with drug therapy was 87%, 60%, 68% and 51%, respectively, for all treatments. It was independent from the disease duration. Male were more compliant than female (P = 0.012).

CONCLUSION

Half of the patients with temporal arteritis are non-compliant with drug therapy. The questionnaire is simple. It can be used in everyday clinical practice to study and improve patient compliance.

Hyperlipidemic profiles during remission in childhood idiopathic nephrotic syndrome

Hyperlipidemia, an important characteristic of idiopathic nephrotic syndrome in children (NS), is usually observed during the active phase of the disease and disappears with the resolution of the proteinuria. However, persisting lipid anomalies during remission have been reported in a few studies and raise the question of the later development of atherosclerosis. Plasma lipid profiles in 25 children with NS at remission, with or without active prednisone treatment, were compared with those of an age-matched population. The results indicate that plasma total and LDL-cholesterol levels were above the 95(th) percentile for age and sex in 12 of the 25 patients (48%) with 7 of them having apolipoprotein B and triglyceride concentrations above the 95(th) percentile. Moreover, frequently relapsing children were more likely to have abnormal lipid profile during the remission. We conclude that close monitoring of lipid levels during the remission of the NS especially in those with frequent relapses, is necessary to select the high-risk patients.