Paralysie périodique thyréotoxique hypokaliémique : quatre observations et revue de la littérature

Purpose

Periodic thyrotoxic hypokalemic paralysis (TPP) is a neuromuscular complication of hyperthyroidism. It is more common in young Asian males than in Caucasian and African patients. We report four new cases and review the literature.

Case reports

Four consecutive patients were diagnosed with TPP. They were all men with a median age of 34.5 years at presentation. Two patients originated from the Philippines, one was African and one was Caucasian ethnic background. They all presented with a paresis or flaccid paralysis, without respiratory failure. Previous similar episodes in their past medical history, the presence of profound hypokalemia (mean serum potassium level of 2 mmol/L) and the presence of clinical and biological signs of hyperthyroidism led to the diagnosis of TPP. All four patients were diagnosed with Graves’ disease. Outcome was favourable in all four patients with the symptomatic treatment of TPP and treatment of Graves’ disease.

Conclusion

TPP is a severe condition, due to a dysfunction of the Na⁺-K⁺ ATPase pump. Initial management relies on β-blocker treatment and careful potassium supplementation. Then, medical or surgical etiological treatment of the thyrotoxicosis is essential to prevent a recurrence. The disease is probably underdiagnosed: it must be suspected when a profound hypokaliema resolves very quickly (< 12 hours); hyperthyroidism should always be included in the differential diagnosis of a paresis associated with hypokalemia.     

Circulating miR-133a and miR-423-5p fail as biomarkers for left ventricular remodeling after myocardial infarction

Background

Recent studies have suggested that the microRNAs miR-133a and miR-423-5p may serve as useful biomarkers in patients with left ventricular (LV) heart failure or with LV remodeling after myocardial infarction (MI). These results were however obtained in small series of patients and control subjects were used as reference groups. Whether these microRNAs may be indicators of the degree of LV remodeling after MI is unknown.

Methods

246 patients with a first anterior Q-wave MI were included. Serial echocardiographic studies were performed at hospital discharge, 3 months, and 1 year after MI and analyzed at a core laboratory. We investigated the temporal profile (baseline, 1, 3 and 12 months) of circulating miR-133a and miR-423-5p and their relations with cardiac biomarkers (B-type natriuretic peptide, C-reactive protein, and cardiac troponin I) and LV remodeling during the 1 year follow-up.

Results

There were time-dependent changes in the levels of circulating miR-133a and miR-423-5p with significant increase of miR-133a at 12 months compared to 3 months and significant increase of miR-423-5p at 1, 3, and 12 months compared to baseline. However, miR-133a and miR-423-5p were not associated with indices of LV function and LV remodeling serially assessed during a 1 year period after an acute anterior MI, nor with B-type natriuretic peptide.

Conclusions

Circulating levels of miR-133a and miR-423-5p are not useful biomarkers of LV remodeling after MI.     

Enhancement of social novelty discrimination by positive allosteric modulators at metabotropic glutamate 5 receptors: adolescent administration prevents adult-onset deficits induced by neonatal treatment with phencyclidine

Metabotropic glutamate-5 receptors (mGluR5), which physically and functionally interact with N-methyl-d-Aspartate (NMDA) receptors, likewise control cognitive processes and have been proposed as targets for novel classes of antipsychotic agent. Since social cognition is impaired in schizophrenia and disrupted by NMDA receptor antagonists like dizocilpine, we evaluated its potential modulation by mGluR5. Acute administration (0.63–40 mg/kg) of the mGluR5 positive allosteric modulators (PAMs), 3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide (CDPPB) and ADX47273, reversed a delay-induced impairment in social novelty discrimination (SND) in adult rats. The action of CDPPB was blocked by the mGluR5 antagonist, 2-methyl-6-(phenylethynyl)-pyridine (2.5–10 mg/kg), and was also expressed upon microinjection into frontal cortex (0.63–10 μg/side), but not striatum. Supporting an interrelationship between mGluR5 and NMDA receptors, enhancement of SND by CDPPB was blocked by dizocilpine (0.08 mg/kg) while, reciprocally, dizocilpine-induced impairment in SND was attenuated by CDPPB (10 mg/kg). The SND deficit elicited by post-natal administration of phencyclidine (10 mg/kg, days?7–11) was reversed by CDPPB or ADX47273 in adults at week?8. This phencyclidine-induced impairment in cognition emerged in adult rats from week?7 on, and chronic, pre-symptomatic treatment of adolescent rats with CDPPB over weeks?5–6 (10 mg/kg per day) prevented the appearance of SND deficits in adults until at least week?13. In conclusion, as evaluated by a SND procedure, mGluR5 PAMs promote social cognition via actions expressed in interaction with NMDA receptors and exerted in frontal cortex. MGluR5 PAMs not only reverse but also (when given during adolescence) prevent the emergence of cognitive impairment associated with a developmental model of schizophrenia.     

The influence of drug use in university hospitals on the pharmaceutical consumption in their surrounding communities

Aim

To investigate the influence of hospital drug choices on pharmaceutical consumption for nine competitive classes in the surrounding community.

Methods

Ecological study. Data from the national survey on drugs in hospitals were used to extract quantities purchased by 25 French university hospitals for three ‘hospital classes’ (EPOs, LMWHs and setrons) and six ‘ambulatory classes’ (PPIs, ACEIs and ARBs, statins, α-adrenoreceptor antagonists (AAAs) and selective serotonin re-uptake inhibitors SSRIs). Re-imbursed quantities for patients living in the hospital''s catchment area were extracted from the national health insurance database. The relationship between the use of a brand in hospitals and their catchment areas was assessed using multivariate linear regressions with instrumental variables.

Results

An increase of 1 day of treatment with one brand in the hospital was associated with a significant increase of 2.8 days of treatment with the same brand in the catchment area. However, results strongly varied according to classes. An increase of 1 day of treatment in the hospital was significantly associated with an increase of 0.21 day for ‘hospital classes’ and 21.8 days for ‘ambulatory classes’ in the catchment area. Strong variations were seen across ‘ambulatory classes’. The effect was maximal for cardiovascular classes and not significant for AAAs and SSRIs. The size of the effect also varied with hospital characteristics: small and proximity university hospitals exerted the greatest influence.

Conclusions

Hospital consumption influences the use of drugs in the community. A significant effect was found, especially for competitive classes used on a long-term basis. The economic consequences of these findings need to be addressed.     

Prediction of dose-hepatotoxic response in humans based on toxicokinetic/toxicodynamic modeling with or without in vivo data: A case study with acetaminophen

In the present legislations, the use of methods alternative to animal testing is explicitly encouraged, to use animal testing only ‘as a last resort’ or to ban it. The use of alternative methods to replace kinetics or repeated dose in vivo tests is a challenging issue. We propose here a strategy based on in vitro tests and QSAR (Quantitative Structure Activity Relationship) models to calibrate a dose–response model predicting hepatotoxicity. The dose response consists in calibrating and coupling a PBPK (physiologically-based pharmacokinetic) model with a toxicodynamic model for cell viability. We applied our strategy to acetaminophen and compared three different ways to calibrate the PBPK model: only with in vitro and in silico methods, using rat data or using all available data including data on humans. Some estimates of kinetic parameters differed substantially among the three calibration processes, but, at the end, the three models were quite comparable in terms of liver toxicity predictions and close to the usual range of human overdose. For the model based on alternative methods, the good adequation with the two other models resulted from an overestimated renal elimination rate which compensated for the underestimation of the metabolism rate. Our study points out that toxicokinetics/toxicodynamics approaches, based on alternative methods and modelling only, can predict in vivo liver toxicity with accuracy comparable to in vivo methods.     

Solid-Solid Transformation in Racemic Ibuprofen

Purpose

To clarify the polymorphism of racemic Ibuprofen and to determine the kinetic of the phase transformation that follows crystallisation of phase II.

Methods

Differential Scanning Calorimetry (DSC), X-ray powder diffraction and Hot Stage Microscopy are complementarily used to perform a kinetic investigation of the particular temperature range where competition between the occurrence of phases I and II is suspected.

Results

Experiments performed with the three techniques reveal that at 273?K the crystallisation to phase II is then followed by a solid-solid transition towards phase I. This transformation is exothermic (conversion enthalpy of 8.0?±?0.5?kJ/mol), which proves that the two phases form a monotropic set. The kinetics of conversion deduced from X-Ray experiments follows a Johnson-Mehl-Avrami equation and the Hot Stage Microscopy allows us to establish that the transformation proceeds by the growth of some nuclei of phase I probably formed at lower temperature.

Conclusions

These results allow us to precise the stability pattern of racemic Ibuprofen and to establish the kinetic conditions of appearance and interconversion of the different phases. Therefore such real time resolved investigations would help if applied in the screening of polymorphs when competitive crystallisations occur.     

Preceptor questioning and student critical thinking.

Questioning is fundamental to student learning. Not only does it enable students to elevate their level of thinking, but in the process it also affords them the opportunity to deal with their world intelligently. The practice setting is an environment rich in opportunity for enabling critical thinking through the use of questioning. In the preceptorship experience, preceptors are in a prime position to use questioning behaviors that can challenge the way preceptees think, encourage them to justify or clarify their assertions, promote the generation of original ideas, explanations, or solutions to patient problems, provide mental and emotional tools to help resolve dilemmas, promote discussion, and evaluate learning. This article discusses the importance of preceptor questioning for the development and promotion of student critical thinking. Contextually, the authors draw on the findings of a recent study in which preceptor questioning of the knowledge base, decision making, and actions of the preceptee were found to directly bring about or trigger their critical thinking. This article allows for some further reflection on that process and its contribution to the enhancement of the preceptorship experience.     

Formation of ZrC–SiC Composites from the Molecular Scale through the Synthesis of Multielement Polymers

In the field of non-oxide ceramic composites, and by using the polymer-derived ceramic route, understanding the relationship between the thermal behaviour of the preceramic polymers and their structure, leading to the mechanisms involved, is crucial. To investigate the role of Zr on the fabrication of ZrC–SiC composites, linear or hyperbranched polycarbosilanes and polyzirconocarbosilanes were synthesised through either “click-chemistry” or hydrosilylation reactions. Then, the thermal behaviours of these polymeric structures were considered, notably to understand the impact of Zr on the thermal path going to the composites. The inorganic materials were characterised by thermogravimetry-mass spectrometry (TG-MS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). To link the macromolecular structure to the organisation involved during the ceramisation process, eight temperature domains were highlighted on the TG analyses, and a four-step mechanism was proposed for the polymers synthesised by a hydrosilylation reaction, as they displayed better ceramic yields. Globally, the introduction of Zr in the polymer had several effects on the temperature fragmentation mechanisms of the organometallic polymeric structures: (i) instead of stepwise mass losses, continuous fragment release prevailed; (ii) the stability of preceramic polymers was impacted, with relatively good ceramic yields; (iii) it modulated the chemical composition of the generated composites as it led, inter alia, to the consumption of free carbon.