[Phaeochromocytoma revealed by a cardiogenic shock treated by extracorporeal life support]. / Choc cardiogénique révélant un phéochromocytome traité par assistance circulatoire.

Phaeochromocytoma is a catecholamine-secreting tumour that originates from the chromaffin cells in the adrenal medulla in 85% of the cases. Phaeochromocytoma typically presents with the classic signs and symptoms of paroxysmal hypertension, tachycardia, and episodic headache in young adults. However, it rarely may manifest as cardiogenic shock due to a catecholamine induced cardiomyopathy. We report the use of central extracorporeal life support (ECLS) in a young man admitted to our department because of cardiogenic shock caused by phaeochromocytoma.

EMG changes in thigh and calf muscles in fin swimming exercise.

Because previous researchers have reported a reduced lactic acid production that accompanies a delayed or an absent ventilatory threshold (VTh) in water-based exercise, we hypothesized that the metaboreflex, activated by muscle acidosis, might be absent in fin swimming. This motor response, delaying the occurrence of fatigue, is characterized by a decreased median frequency (MF) of electromyographic (EMG) power spectrum. Seven healthy subjects performed a maximal fin swimming exercise protocol with simultaneous recordings of surface EMGs in VASTUS MEDIALIS (VM), TIBIALIS ANTERIOR (TA) and GASTROCNEMIUS MEDIALIS (GM). We computed the root mean square (RMS) and MF and recorded the compound evoked muscle potential (M-wave) in VM. We also measured the propulsive force and oxygen uptake (VO (2)), and determined VTh. VTh was absent in 4/7 subjects and measured at 70-90% of VO (2max) in the other three. In the three studied muscles, the global EMG activity (RMS) increased while the MF decreased in proportion of VO (2), the MF changes being significantly higher in VM (-29%) and GM (-39%) than in TA (-19%). Because no M-wave changes were noted, the MF decline was attributed to the recruitment of low-frequency, fatigue-resistant motor units. Our most important finding is the persistence of the metaboreflex even in a situation of reduced muscle acidosis.

Fin swimming improves respiratory gas exchange.

Data in the literature suggest that compared to dry-land exercise fin swimming might delay the activation of the anaerobic metabolism. To verify this hypothesis, we explored indirect indices such as the oxygen pulse (VO(2)/HR), carbon dioxide production (VCO(2)), and ventilatory threshold, comparing fin swimming exercise to dry-land cycling. Thirteen participants, experienced or inexperienced in fin swimming, completed an incremental fin swimming exercise and a maximal exercise on a cycloergometer with breath-by-breath measurements of heart rate (HR), ventilation (VE), tidal volume (VT), VO(2), VCO(2), and VO(2)/HR and determination of the ventilatory threshold and maximal oxygen uptake (VO(2)max). Compared to dry-land cycling exercise, fin swimming resulted in elevated or absent ventilatory threshold. Although VO(2)max did not differ in either condition, in fin swimming the maximal HR value was lower (-18%, p=0.0072), maximal VO(2)/HR higher (+20%, p=0.0325), and maximal VCO(2) lower (-17%, p=0.0071). We also measured significant reduction of VE, VT, and HR variations for the same VO(2) increase. This study suggests that the anaerobic muscle metabolism might be delayed in fin swimming. An attenuated chemoreflex drive to the heart and respiratory centres exerted by muscle metabolites might explain the depressed cardiopulmonary response to fin swimming.

Optimization and characterization of a flow injection electrochemical system for pentachlorophenol assay.

A flow injection (FI) electrochemical detection system has been developed and optimized for the determination of pentachlorophenol (PCP) in contaminated soil. PCP was oxidized to tetrachloro-1,4-benzoquinone (1,4-TCBQ) with a high yield using bis(trifluoroacetoxy)iodobenzene in 0.1 M tartaric acid, pH 2.0, at ambient temperature. Upon rapid reaction with immobilized glucose oxidase, the detection and amplification scheme was completed as the reduced form of 1,4-TCBQ or tetrachloro-1,4-hydroquinone was reoxidized to 1,4-TCBQ at the surface of the glassy carbon electrode (+ 0.40 V vs Ag/AgCl). Rapid electron exchange between the enzyme and its glucose substrate provided a non-rate-limiting current toward the electrode. The FI electrochemical system was linear up to 1 µM oxidized PCP with a detection limit of 10 nM and exhibited a reproducibility of ±0.6% over 165 repeated analyses during 14 h of continuous operation. When applied to PCP-contaminated soil samples, the results obtained from the FI electrochemical system compared well with those of the HPLC standard method.

A Combined Chemical and Electrochemical Approach Using Bis(trifluoroacetoxy)iodobenzene and Glucose Oxidase for the Detection of Chlorinated Phenols.

A novel electrocatalytic approach using a chemical reaction and an enzymatic reaction has been developed for the measurement of 18 chlorophenol congeners, including highly chlorinated pollutants such as pentachlorophenol, 2,3,5,6-tetrachlorophenol, 2,3,4,6-tetrachlorophenol, and several trichlorophenols. Chlorophenols were oxidized to chlorobenzoquinones with very high yields using bis(trifluoroacetoxy)iodobenzene in 0.1 M trichloroacetic acid, pH 1.5, at ambient temperature. UV-visible spectrophotometry, cyclic voltammetry, and HPLC have been used to characterize the reaction products and yields. Together with glucose oxidase immobilized on a working glassy carbon electrode (+0.45 V vs Ag/AgCl), chlorinated benzoquinones have been demonstrated to be efficient mediators in a glucose oxidase/glucose system. In this approach, glucose oxidase was readily reduced by excess glucose to provide a non-rate-limiting source of electron flow toward the electrode. The oxidation products of chlorophenols then recycled the reduced glucose oxidase to its active oxidative state, i.e., mediating the rate-limiting electron transfer from the enzyme to the electrode. At pH 3.5, linear behavior of the current response was observed up to 200 nM for all chlorophenol oxidation products. The detection limit of this method for both pentachlorophenol and 2,3,5,6-tetrachlorophenol was about 4 nM, which is close to the maximum allowable contamination level of pentachlorophenol in water samples (2.7 nM). The detection limit obtained for pentachlorophenol could also be considered superior to the result obtained with the PCP immunoassay technology (13.3 nM).