Ablation of Cx47 in transgenic mice leads to the loss of MUPP1, ZONAB and multiple connexins at oligodendrocyte-astrocyte gap junctions.

Oligodendrocytes in CNS are linked to astrocytes by heterotypic gap junctions composed of Cx32 and Cx47 in oligodendrocytes and Cx30 and Cx43 in astrocytes. These gap junctions also harbour regulatory proteins, including ZO-1 and ZONAB. Here, we investigated the localization of multi-PDZ domain protein 1 (MUPP1) at these gap junctions and examined accessory proteins and connexins associated with oligodendrocytes in Cx47-knockout mice. In every CNS region tested, punctate immunolabelling for MUPP1 was found on all oligodendrocyte somata in wild-type mice. These MUPP1-positive puncta were colocalized with punctate labelling for oligodendrocytic Cx32 or Cx47, and with astrocytic Cx30 or Cx43 at oligodendrocyte-astrocyte (O/A) gap junctions, but were not found at astrocyte-astrocyte gap junctions. In Cx47-knockout mice, immunolabelling of MUPP1 and ZONAB was absent on oligodendrocytes, whereas some ZO-1-positive puncta remained. In Cx32-knockout mice, MUPP1 and ZONAB persisted at O/A gap junctions. The absence of Cx47 in Cx47-knockout mice was accompanied by a total loss of punctate labelling for Cx30, Cx32 and Cx43 on oligodendrocyte somata, and by a dramatic increase in immunolabelling for Cx32 along myelinated fibers. These results demonstrate MUPP1 at O/A gap junctions and Cx47-dependent targeting of connexins to the plasma membranes of oligodendrocyte somata. Further, it appears that deficits in myelination reported in Cx47-knockout mice may arise not only from a loss of Cx47 but also from the accompanied loss of gap junctions and their regulatory proteins at oligodendrocyte somata, and that loss of Cx47 may be partly compensated for by elevated levels of Cx32 along myelinated fibers.

Interest of Chromogranin A for diagnosis and follow-up of endocrine tumours.

OBJECTIVE: To determine the interest of Chromogranin A (CgA) determination for diagnosis and follow-up in patients with gastroenteropancreatic endocrine tumours (GEP-ET) and multiple endocrine neoplasia type 1 (MEN-1). PATIENTS AND METHODS: CgA levels were measured with an immunoradiometric assay in 124 sporadic GEP-ET, 34 MEN-1 and 127 controls. Serial determinations were performed in 56 patients (212 visits). Changes in CgA levels over 25% were considered as significant. RESULTS: Using a cut-off value of 130 micro g/l, established from a receiver-operating characteristic curve, the specificity of CgA was 98.4%, with a sensitivity of 62.9%, higher in secreting than in nonsecreting tumours (73%vs. 45%; P < 0.003) and related to the extent of metastatic spreading (P < 0.001). In nonsecreting tumours, the positive predictive value (PPV) of CgA for the presence of metastases was 100% but the negative predictive value (NPV) was only 50%. In MEN-1, high CgA levels indicated a pancreatic tumour with a 100% specificity but the sensitivity was 59%. During the follow-up, the concordance between CgA and tumour evolution was 80%, whatever the secretory status. In patients with carcinoid tumours, the concordance was higher for CgA than for serotonin (81%vs. 54%; P < 0.001). CONCLUSION: Due to its high specificity, CgA determination may help to discriminate the endocrine character of a GEP tumour and to indicate a pancreatic tumour in MEN-1. However, its low NPV in nonsecreting tumours limits its interest for diagnosis and staging. By contrast, serial evaluation of CgA seems of particular interest for the follow-up of GEP-ET tumours.

Polyunsaturated fatty acids in the blood of spontaneously or induced muricidal male Wistar rats.

Serum levels of several n-6 and n-3 polyunsaturated fatty acids were compared in male Wistar muricidal (Mu) and non-Mu rats. The Mu behavior was either spontaneous or induced by long-term isolation, feeding with a starch-enriched polyunsaturated fatty acid diet (PUFA+S), water restriction, or adrenalectomy (ADX). Arachidonic acid (ARA) levels were lower in diet-induced (PUFA+S) Mu rats than in their non-Mu controls. Total n-6 fatty acid levels were also lower in spontaneously Mu rats than in spontaneously non-Mu rats. Docosahexaenoic acid (DHA) and total n-3 fatty acids levels were lower in rats with isolation-induced Mu behavior. The n-3/n-6 ratio was higher in spontaneously Mu rats than in spontaneously non-Mu rats. The changes in ARA levels were greater than those in DHA levels, possibly due to the higher blood-brain barrier passage of arachidonic acid. The results were analyzed in the light of recent results showing a role of PUFAs in human and animal behavior.

[Measurement of salivary cortisol with four commercial kits]. / Mesure du cortisol salivaire par quatre trousses du commerce.

Salivary cortisol was determined with four commercially available immunoassays: one enzyme-immunoassay (Cortisol Biotrol), two fluoro-immunoassays (TDX, Abbott; Stratus, Baxter) and one radioimmunoassay (Coat-A-Count, Behring). In order to improve the sensitivity of these immunoassays, it was necessary to increase sample volumes. Thus an extraction step had to be included in the procedure. It was performed with either methylene chloride or Bond Elut. However, the Coat-A-Count kit may be applied directly on salivary aliquots. The results obtained were compared to those yielded by the reference technique which includes a chromatographic step on Sephadex LH 20. According to the present data (n = 20) no kit appears to be adequate for salivary cortisol measurement at any level, at least in the conditions applied in this study. However, the introduction of a chromatographic step in the procedure improved greatly the specificity. Nevertheless, the best results were obtained with the Coat-A-Count kit. Indeed, they were generally similar to those of the reference technique, but some discrepancies were observed at low levels.

GC/MS detection of paraffins in a case of lipoid pneumonia following occupational exposure to oil spray.

A case of lipoid pneumonia following occupational exposure to oil spray is described. Biological fluids (broncho-alveolar lavage and pleural fluid) are analyzed to determine if the compounds found in the industrial oils are present. The samples are purified using high-performance thin-layer chromatography, and after extraction, the compounds were submitted to infrared spectroscopy. Direct hexane extraction of biological fluids is also performed, followed by gas chromatography/mass spectrometry (GC/MS).