A dataset from a 3-year network of field measurements of soil organic nitrogen mineralization under a mild oceanic temperate climate

Improved assessment and prediction of soil organic nitrogen (SON) mineralization is essential, as it contributes significantly to the nitrogen (N) nutrition of crops and remains a major economic and environmental challenge. SON mineralization is a function of soil properties, land use and climate, which led us to monitor a network of 137 cultivated fields covering the wide diversity of soils, crop rotations and cropping practices throughout Brittany (France). SON mineralization was quantified by the mineral N balance calculated for a maize crop not fertilized with N; it was determined by measuring soil mineral N (SMN) in the 0-90 cm soil profile in March (Ni) and October (Nf) and N uptake by the maize crop, and predicting nitrate leaching (N_leached) using the STICS model. SMN and plant N uptake were measured in triplicate. To predict N_leached, STICS was initialized at the date of Ni measurement. In addition, the experimental design was based on estimating SON for three consecutive years (2012-2014) to improve the accuracy of measuring mineralization. An indicator of the cropping system (I_Sys) was developed that integrated well the effects of crop rotation and the frequency of manure application; it can be considered a good index of effects of the cropping system on SON mineralization. This dataset may be used for a variety of applications, such as analysing effects of soil properties, cropping history and climatic conditions on SON mineralization, or evaluating the accuracy of soil-plant models (e.g. STICS, CERES).

SAT0309 CARDIAC MAGNETIC RESONANCE IMAGING ELEVATED NATIVE MYOCARDIAL T1 IS PREDICTIVE FOR THE DEVELOPMENT OF MYOCARDIAL DYSFUNCTION IN SYSTEMIC SCLEROSIS

Background:

All patients included in the study fulfilled the ACR/EULAR classification criteria for SSc. We prospectively included patients who underwent at least two CMR at 1.5T, including native T1 and T2 mapping (which give account for myocardial fibrosis and myocardial edema respectively), left and right ventricles morphology and functional assessment, and Late Gadolinium Enhancement (LGE) as a part of routine follow-up between 2015 and 2019.

Objectives:

To evaluate the prognostic value of initial abnormal T1 mapping.

Methods:

All patients included in the study fulfilled the ACR/EULAR classification criteria for SSc. We prospectively included patients who underwent at least two CMR at 1.5T, including native T1 and T2 mapping (which give account for myocardial fibrosis and myocardial edema respectively), left and right ventricles morphology and functional assessment, and Late Gadolinium Enhancement (LGE) as a part of routine follow-up between 2015 and 2019.

Results:

Sixty-three patients underwent at list two CMR during the study period. Forty-three patients were women. Mean age was 52.5±15.5 years old. Follow-up duration between the initial and the follow-up CMR was 14.5±11.5 months. Forty-one had diffuse SSc. The mean native T1 was 1066.8 ±44.6 ms. Twenty-one patients suffered from cardiac clinical manifestations. Nine patients died during the follow-up. Thirty patients (47.6%) had elevated T1 (ET1) with mean T1 1105.4±36.7 ms at the time of initial CMR. Initial ET1 was clearly correlated with: 1/ alteration of Left Ventricle (LV) Ejection fraction (EF) (r=0.5, p<0.0001) during the study period, 2/LV dilatation at initial screening and follow up (r=0.22, p=0.03 and r=0.3, p=0.02). Regarding Right ventricle, initial ET1 was correlated with initial Right Ventricle (RV) dilatation (r=0.3, p=0.02) but neither with RV volume nor RVEF at follow-up. Interestingly, initial ET1 correlated with pericardial effusion (r=0.3, p=0.003) which is known to be a pejorative prognostic factor. Seventeen patients (28%) had LGE but the ET1 at initial screening and follow-up was not correlated with LGE.

Six patients had elevated T2 (ET2) which correlated with initial and follow up LV dilatation (r=0,32, p=0.002 and r=0.5, p<0.0001 respectively) but not with LVEF during the period study. Among other parameters, initial increased BNP was correlated with follow up ET1 LVEF and RVEF (r=0.4, p=0.01; r=0.35, p=0.007; r=0,37, p=0.005 respectively). In the same way, initial Pulmonary Arterial Hypertension (PAH) was correlated with follow up ET1 (r=0.3, p=0.02). Initial ET1 did not correlate with age, sex, cardiovascular risk factors, cardiac manifestations or death.

Conclusion:

Assessment of diffuse myocardial fibrosis by native T1 is predictive of the occurrence of cardiac dysfunction at the follow-up as initial ET1 was associated with decreased left ventricular function and LV and RV dilatations). These data highlights the potential role of CMR with T1mapping in initial screening and at the follow-up and provides new insights in the cardiac SSc follow up strategy.

References:

[1]Poindron V, Chatelus E, Canuet M, Gottenberg JE, Arnaud L, Gangi A, Gavand PE, Guffroy A, Korganow AS, Germain P, Sibilia J, El Ghannudi S, Martin T.T1 mapping cardiac magnetic resonance imaging frequently detects subclinical diffuse myocardial fibrosis in systemic sclerosis patients.Semin Arthritis Rheum. 2019 Jun 19.

Disclosure of Interests:

None declared

Thromboxane A2 modulates cisplatin-induced apoptosis through a Siva1-dependent mechanism

Thromboxane A(2) (TXA(2)) is an important lipid mediator whose function in apoptosis is the subject of conflicting reports. Here, a yeast two-hybrid screen for proteins that interact with the C-terminus of the TXA(2) receptor (TP) identified Siva1 as a new TP-interacting protein. Contradictory evidence suggests pro- and anti-apoptotic roles for Siva1. We show that a cisplatin treatment induces TXA(2) synthesis in HeLa cells. We demonstrate that endogenous TP stimulation promotes cisplatin-induced apoptosis of HeLa cells and that such modulation requires the expression of Siva1, as evidenced by inhibiting its endogenous expression using siRNAs. We reveal that, upon stimulation of TP, degradation of Siva1 is impeded, resulting in an accumulation of the protein, which translocates from the nucleus to the cytosol. Translocation of Siva1 correlates with its reduced interaction with Mdm2 (an inhibitor of p53 signalling), as well as with its increased interaction with TRAF2 and XIAP (known to enhance pro-apoptotic signalling). Our data provide a model that reconciles the pro- and anti-apoptotic roles that were reported for Siva1 and identify a new mechanism for promoting apoptosis by G protein-coupled receptors. Our findings may have implications in the use of cyclo-oxygenase inhibitors during cisplatin chemotherapy and might provide a target to reduce cisplatin toxicity on non-cancerous tissues.

[Usefulness of diastolic deceleration time assessed by transthoracic Doppler measurement in the detection of sustained microvascular obstruction in STEMI patients treated by primary PTCA]

AIMS

To assess the value of coronary flow measurement by transthoracic Doppler technique in the detection of "no-reflow" phenomenon.

METHODS

Fourteen patients with first anterior wall infarction treated by successful (TIMI3) primary percutaneous angioplasty and left descending coronary artery stenting were investigated. Myocardial perfusion following PCI was assessed by (i) ST-segment resolution, (ii) MRI-detected microvascular obstruction (early hypoenhancement), (iii) coronary flow pattern measurement by transthoracic Doppler technique.

RESULTS

Sustained impairment of myocardial perfusion following PCI was observed in a large proportion of the cohort (36% by MRI, 43% by ST regression analysis). Patients with a diastolic deceleration time inferior to 482 ms had higher troponin and CK peak value, higher wall motion index score, lower ST resolution and lower LVEF assessed by MRI. The concordance of the three methods was 80%.

CONCLUSION

The measurement of diastolic deceleration time by transthoracic Doppler technique is a reliable technique to identify microvascular obstruction following PCI in acute anterior STEMI. A DDT inferior to 482 ms is associated with sustained "no-reflow" phenomenon.

[Chronic constrictive pericarditis: MR imaging features]

Chronic constrictive pericarditis is defined by an increase in the rigidity of the pericardium resulting in impairment of the ventricular filling conditions. Cardiac MR is both a morphological and functional study always complemented by multi-detector CT. Morphological analysis is based on axial, longitudinal long axis and short axis views on Turbo (fast) SE Dark Blood and CINE sequences. Functional analysis is based on real-time acquisitions in the short axis at the base of the ventricles by comparing spontaneous breathing and deep breathing. The excursion of the interventricular septum is a reliable sign of constriction. The study is supplemented by phase contrast acquisitions. In the setting of persistent inflammation or free pericardial fluid, delayed enhancement 3D and 2D sequences including Phase Sensitive Inversion Recovery (PSIR) are useful.

Teaching and assessment of professional attitudes in UK dental schools - commentary

The General Dental Council expects professionalism to be embedded and assessed through-out the undergraduate dental programme. Curricula need therefore to accommodate these recommendations. A stroll poll of UK dental schools provided a basis for understanding the current methods of teaching and assessing professionalism. All respondent schools recognised the importance of professionalism and reported that this was taught and assessed within their curriculum. For most the methods involved were largely traditional, relying on lectures and seminars taught throughout the course. The most common form of assessment was by grading and providing formative feedback after a clinical encounter. Whilst clinical skills and knowledge can perhaps be readily taught and assessed using traditional methods, those involved in education are challenged to identify and implement effective methods of not only teaching, but also assessing professionalism. A variety of standalone methods need to be developed that assess professionalism and this will, in turn, allow the effectiveness of teaching methods to be assessed.

Role of pre-infarction angina and inflammatory status in the extent of microvascular obstruction detected by MRI in myocardial infarction patients treated by PCI

BACKGROUND/OBJECTIVES

The extent of microvascular obstruction (MVO) during myocardial infarction referred to as the "no-reflow phenomenon", may determine myocardial damage. Our study aimed to investigate the incidence and the influencing factors of MVO in patients with ST-elevation myocardial infarction (STEMI) treated by primary percutaneous intervention (PCI).

PATIENTS, METHODS

Using contrast-enhanced MRI, microvascular obstruction was defined as early hypoenhancement. Contrast defects were scored from 0 (no hypoenhancement) to 3 (strong hypoenhancement). 50 patients (56+/-11 years) with STEMI underwent PCI. Contrast-enhanced MRI (6+/-2 days after STEMI) and biochemical parameters were evaluated.

RESULTS

Microvascular obstruction (score 1 to 3) was observed in 90% of the patients and major microvascular obstruction (score 2-3) in 54%. In univariate analysis, leukocytes and CRP levels were associated with MVO, whereas pre-infarction angina and prior medication by aspirin or calcium channel antagonist appeared protective. Microvascular obstruction intensity positively correlated with baseline inflammation status assessed by C-reactive protein and leukocytes (rho=0.43 and rho=0.44; p=0.003), the peak of CK (rho=0.56; p=0.01) or Troponin I (rho=0.59; p=0.01) and negatively correlated with LVEF (rho=-0.44; p=0.002). Multivariate analysis identified the absence of pre-infarction angina as the only independent predictor for microvascular obstruction (odds ratio, 8.35, 95% confidence interval 1.27-54.71; p=0.027).

CONCLUSION

MRI-detected microvascular obstruction has a high incidence in patients with STEMI treated by primary PCI and determines post-MI LVEF even in patients with post PCI TIMI 3 flow score. Pre-infarction angina appears to be an independent determinant of the extent of MVO detected by MRI.

Variations of 210Po and 210Pb in various marine organisms from Western English Channel: contribution of 210Po to the radiation dose

Measurements of (210)Po were carried out in various marine matrices (mussels, oysters, seaweed, fish, and abalones) and in seawater at several points along the French coast, over a period of 2 years (2003-2005). These measurements contribute to a better knowledge of this element, since few recent data exist for the French coast. Marked seasonal variations have been revealed in some species and there are differences according to the way of life of these species. Activities in mussels (Mytilus edulis) and oysters (Crassostrea gigas) are similar and varying between 90 and 600 Bq kg(-1) (d.w.). Activities in macroalgae (Fucus serratus) are lowest, between 4 and 16 Bq kg(-1) (d.w.). In oyster, abalone (Haliotis tuberculata) and fish (Solea solea, Sparus sp.), the strongest activities are measured in the digestive glands, the gills and the gonads. (210)Po/(210)Pb ratios in all cases have values of more than one for all species. From a significant number of measurements, CFs were calculated for seaweed (between 4.6 x 10(3) and 5.0 x 10(3)) and for molluscs, with highest CFs (>10(5)) found for the digestive gland and gills of the oysters, the digestive gland of the abalones and the liver of fish. Finally, the activities measured have made it possible to estimate the internal dose from chronic exposure due to (210)Po received by the marine organisms (0.05 microGh(-1) for macroalgae, between 0.70 and 1.5 microGh(-1) for mussels and oyster), and the contribution of seafood to the dose received by humans (46-129 microSvy(-1)).

Enhanced solubilization of arsenic and 2,3,4,6 tetrachlorophenol from soils by a cyclodextrin derivative

The application of extracting aqueous solutions with cyclodextrins in several soil remediation technologies has been increasingly studied but little is known about their removal capacities toward the inorganic species. Herein, the effectiveness of cyclodextrins (CDs) in extracting arsenic, copper, and iron from a mining soil is presented. In a preliminary test of four types of CD aqueous solutions, only the addition of carboxylmethyl-beta-cyclodextrin CMCD (a cyclodextrin derivative) led to a significant enhancement in arsenic removal. An increase in the concentration of copper and iron in the leachates was also observed with CMCD. Kinetic study of arsenic release was carried out at two temperatures (20 and 35 degrees C). The arsenic concentration in the leachates increases with increasing cyclodextrin concentration. At an 80 mM CMCD concentration, arsenic, copper, and iron released in filtrates were about 20-, 1,000-, and 4,000-fold greater, respectively, than that obtained using deionized water. In the soil system, the CMCD capacity removal was found to be higher for cations than for arsenic. Because the tetrachlorophenol can co-occur with arsenic and copper in several contaminated sites, its solubilization by CMCD was also investigated. Extraction experiments were performed to extract 2,3,4,6 tetrachlorophenol (TeCP) in spiked soil with CMCD. The results of batch experiments have shown that CMCD could significantly increase the TeCP extraction from soil. CD sorption on soils as quantified by a fluorescence technique was low, indicating no significant loss of CD during the leaching experiments. The use of CMCD as a flushing agent to enhance the removal of both inorganic and organic pollutants from mixed-contaminated soils appears as a promising remediation method.

Apport de l’IRM dans l’exploration des anomalies cardiaques congénitales et des gros vaisseaux

Management of congenital heart diseases (CHD) frequently is a diagnostic challenge. MRI, as a complement to echocardiography, plays an important role in the non-invasive evaluation of these anomalies. MRI allows high resolution anatomical evaluation of these structures in multiple planes as well as functional evaluation. These features are helpful to further characterize extra-cardiac anomalies that may be difficult to assess at US and even angiography. MRI is thus a valuable imaging tool in the evaluation of CHD.

Degradation of pentachlorophenol in cyclodextrin extraction effluent using a photocatalytic process

This work evaluates a process for the elimination of pentachlorophenol (PCP) from effluents provided by a cyclodextrin-assisted flushing of contaminated soils. The effectiveness of photocatalytic degradation of PCP in several cyclodextrin (CD) solutions was evaluated using TiO2 as a photocatalyst. Effects of CD type on PCP degradation rate were studied at two pH values. A similar effect was observed for all CDs used on degradation rate of PCP and the decay of PCP was found to be less extensive at pH 11 than at pH 7. The kinetic orders of the photocatalytic reactions of PCP for all of the solutions have been determined. The first-order rate constants were found to be 0.0884, 0.0362, 0.0197 and 0.0053 min(-1) in CD solutions, respectively, at 0, 1, 2 and 5 mmol l(-1) of CD. Batch experiments were performed in order to study the CD extraction enhancement of PCP previously adsorbed on soil. The results show that the removal capacity of PCP from soil increases with CD concentration (from 0 to 5 mmol l(-1)). When the CD concentration was 5 mmol l(-1), an extraction of about 70% of PCP adsorbed on soil was observed, whereas only 37% was removed when water was used as the flushing solution. The optimal conditions for such a coupled method depend on the nature and concentration of the extracting agent and also on the photocatalytic experimental conditions. This work revealed that the coupling of cyclodextrin-enhanced solubilization and photocatalytic treatment is a promising method for contaminated soil remediation.

[Pulmonary plasmacytoma: about two new cases and review of the literature]

INTRODUCTION

Extramedullary plasmacytoma is an uncommon plasma cell malignancy mainly located to the upper aerodigestive tract. Primary pulmonary plasmacytoma is extremely rare.

EXEGESIS

We report two new cases of primary pulmonary plasmacytoma and then proceed to a review of the literature concerning 35 similar cases previously described.

CONCLUSION

Complete or partial responses were obtained in 24 cases (65%). Five patients (14%) have developed multiple myeloma within 3 years following plasmacytoma diagnostic. In spite of sustained responses with radiotherapy or chemotherapy, surgical resection while feasible remains the first therapeutic option.

Cyclodextrin-enhanced solubilization of pentachlorophenol in water

The solubilization of pentachlorophenol (PCP) by beta-cyclodextrin (beta-CD) and three of its most used derivatives, methyl-beta-cyclodextrin (MCD), hydroxypropyl-beta-cyclodextrin (HPCD) and carboxymethyl-beta-cyclodextrin (CMCD), has been investigated. The formation of soluble inclusion complexes between PCP and cyclodextrin (CDs) increases the aqueous solubility of PCP. Due to the ionizable nature of PCP, the effects of pH and ionic strength on the equilibrium complexation were evaluated. All CDs were found to form 1:1 inclusion complexes. Equilibrium constants calculated from solubility enhancement experiments revealed that the stability of the complexes was dependent on the polarity of the compound, on the ionic strength and on the cyclodextrin type. In general, weaker equilibrium constants were observed for PCP with beta-CD than with MCD or CMCD. For all CDs, the complexation or the solubilization efficiency of PCP (weak acid) depended on pH and ionic strength. Moreover, we observed that the solubility of the beta-CD/PCP complex was lower than that of the beta-CD molecule and dependent on the ionic strength of the solution. Although the equilibrium constant of PCP/CD complex was found to be higher at pH 3 than at pH 7 in water, extraction of PCP from porous media by a CD solution at neutral pH would be achievable due to the higher PCP aqueous solubility in neutral/basic media.

Radionuclide speciation in effluent from La Hague reprocessing plant in France

Effluent from the La Hague nuclear fuel reprocessing plant was mixed with seawater in order to investigate the fate of the various radionuclides. Thus, a major objective of the present work is to characterize the effluent from La Hague reprocessing plant and to study how the radionuclide speciation changes with time when discharged into the marine environment. Discharges from the La Hague nuclear reprocessing plant represent an important source of artificially produced radionuclides to the North Sea. The transport, distribution, and biological uptake of radionuclides in the marine environment depends, however, on the physicochemical forms of radionuclides in the discharged effluents and on transformation processes that occur after entering the coastal waters. Information of these processes is needed to understand the transport and long-term distribution of the radionuclides. In the present work, a weekly discharged effluent from the nuclear fuel reprocessing plant at Cap La Hague in France was mixed with coastal water and fractionated with respect to particle size and charged species using ultra centrifugation and hollow fiber ultrafiltration with on line ion exchange. The size distribution pattern of gamma-emitting radionuclides was followed during a 62-h period after mixing the effluent with seawater. 54Mn was present as particulate material in the effluent, while other investigated radionuclides were discharged in a more mobile form or were mobilized after mixing with sea water (e.g., 60Co) and can be transported long distances in the sea. Sediments can act as a sink for less mobile discharged radionuclides (Skipperud et al. 2000). A kinetic model experiment was performed to provide information of the time-dependent distribution coefficients, Kd (t). The retention of the effluent radionuclides in sediments was surprisingly low (Kd 20-50), and the sediments acted as a poor sink for the released radionuclides. Due to the presence of non-reacting radionuclide species in the effluent, a major fraction of the radionuclides, such as Cs-isotopes, 106Ru and 125Sb, in the effluent will be subjected to marine transport to the Northern Seas (i.e., the North Sea, Norwegian Sea and the Barents Sea). The La Hague effluent may, therefore, contribute to enriched levels of radionuclides found in the English Channel, including 90Sr, 60Co and Pu-isotopes, and also 106Ru and 125Sb.

Solubilization of the neutral and charged forms of 2,4,6-trichlorophenol by beta-cyclodextrin, methyl-beta-cyclodextrin and hydroxypropyl-beta-cyclodextrin in water

The solubilities of the neutral and charged forms of 2,4,6-trichlorophenol (TCP) in beta-cyclodextrin (beta-CD) and two of its most used derivatives: methyl-beta-cyclodextrin (MCD) and hydroxypropyl-beta-cyclodextrin (HPCD) solutions were investigated. The three cyclodextrins were found to form 1:1 inclusion complexes. Binding constants estimated from an enhancement solubility method revealed that the stability of the complexes was dependent on the polarity of the compound and on the cyclodextrin used.In general, weaker binding constants were observed for TCP with beta-CD than with HPCD or MCD. The solubilization efficiencies towards TCP can be ranked in the following order: MCD > HPCD > beta-CD. For all cyclodextrins, the stability constant of neutral TCP (logK(ow)=3.85) was larger than that of charged TCP (logK(ow)=1.4).A precipitation occurred in TCP/beta-CD solution (around 10 g/l beta-CD concentration) at pH 3. However, this phenomenon is not observed for TCP/beta-CD solution at pH 8.8.

Concentration and distribution of 210Po in the tissues of the scallop Chlamys varia and the mussel Mytilus edulis from the coasts of Charente-Maritime (France)

Polonium-210 (210Po) has been analysed in the soft parts of two bivalves species, the scallop Chlamys varia and the common mussel Mytilus edulis, from the Bay of La Rochelle and Ré Island, on the French Atlantic coast. Between those sites, the highest 210Po concentrations have been found in whole scallop soft parts from La Rochelle, reaching 1,181 +/- 29 Bq kg(-1) dry weight (dwt), a size effect being related to the highest 210Po concentration in the smallest scallops. The results show a significant difference in concentrations for similar size individuals between species in each site (C. varia > M. edulis) and between sites for each species (Ré Island > Bay of La Rochelle). Very high 210Po concentrations have been found in the digestive gland of C varia, ranging 3,150-4,637 Bq kg(-1) dwt. Thus, the digestive gland contains up to 60% of the radionuclide. Subcellular investigations have shown that approximately 40% of the 210Po contained in the digestive gland is in the cytosolic fraction, suggesting a high bioavailability of the 210Po from this fraction to the trophic upper level. Calculations will show that approximately 4 kg of scallops flesh intake would be necessary to reach the annual incorporation limit of 1 mSv.

Cholesterol crystal embolization simulating focal myositis

Cholesterol crystal embolization usually produces characteristic skin lesions. We report a case responsible for myositis of the calf without suggestive skin lesions. The outcome in this 58-year-old patient was spontaneously favorable. Cholesterol crystal embolization can produce a range of clinical symptoms, with the skin, kidneys, and eyes being the most common targets. Generalized forms can result in systemic disease. The diagnosis rests on histological findings, and the treatment is symptomatic. Anticoagulants have been shown to worsen the manifestations, whereas antiplatelet therapy may be useful.

Myocardial flow reserve parametric map, assessed by first-pass MRI compartmental analysis at the chronic stage of infarction

Regional myocardial flow and flow reserve (MFR) were assessed by compartmental analysis of Gd-enhanced MRI first-pass data in 7 patients with atypical chest pain, and in 15 patients with previous transmural myocardial infarction. The FE product (Flow x Extraction coefficient), derived from the modified Kety equation, was measured in regions corresponding to the Tetrofosmine-SPECT fixed defect and in remote normal regions. The FE product at rest and hyperemic FE product were similar in healed revascularized tissues (70.5 +/- 15.6 and 112.5 +/- 19.5 ml/mn/100 g, respectively) and in normal myocardium (76.2 +/- 18.3 and 142.2 +/- 33.0, respectively). In contrast, the FE index (48.8 +/- 15.2 and 60.7 +/- 18.0, respectively, P < 0.01 versus the two previous groups) and the MFR (1.27 +/- 0.20 vs. 1.91 +/- 0.29 in normal regions) were reduced in healed fibrotic tissues when the infarct-related artery remained occluded. Myocardial flow reserve maps allowed correct identification of regions corresponding to an occluded infarct-related artery.

[Cutaneous pyoderma gangrenosum with hepatosplenic localization and monoclonal gammapathy. A case report]

Pyoderma gangrenosum is an ulcerative disease of the skin. The histopathological lesions are nonspecific, characterized by a diffuse neutrophilic infiltrate in the dermis. Pyoderma gangrenosum is associated with inflammatory, digestive or articular disease, or acute or chronic hemotology disorders in 50% of the cases, more rarely with monoclonal gammapathy. A visceral localization of pyoderma gangrenosum is rare, simulating a systemic disease or an underlying neoplasia. We report a case of cutaneous pyoderma gangrenosum with splenic and hepatic localizatios associated with an IgG monoclonal gammapathy. We emphasize the efficacy of immunosuppressor treatment and the importance of long-term monitoring of these patients.

Intracellular pH determination of pristinamycin-producing Streptomyces pristinaespiralis by image analysis

Intracellular pH (pH(i)) is an essential parameter in the regulation of intracellular processes. Thus, its measurement might provide clues regarding the physiological state of cells cultivated in vitro. pH(i) of the filamentous, pristinamycin-producing Streptomyces pristinaespiralis was determined by epifluorescence microscopy and image analysis using the pH-sensitive fluorescent probe BCECF-AM [2', 7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein, acetoxymethyl ester]. Staining cell culture samples (OD(660)=1) of S. pristinaespiralis with 20 microM BCECF at 28 degrees C for 30 min yielded a green/red fluorescence ratio (R:(527/600)) that correlated with the pH(i) of the cells for values ranging from 6.5 to 8.5. When S. pristinaespiralis was cultivated in pristinamycin-producing conditions (in batch mode, with a constant external pH of 6.8), the measured pH(i) varied between 6.3 and 8.7. In fact, pH(i) correlated with the excretion of pristinamycins and glucose consumption during the production process.

Nuclear receptor ligand-binding domains: three-dimensional structures, molecular interactions and pharmacological implications

Nuclear receptors are members of a large family of ligand-inducible transcription factors that regulate gene programs underlying a plethora of (patho)physiological phenomena. The recent determination of the crystal structures of nuclear receptor ligand-binding domains has provided an extremely detailed insight into the intra- and intermolecular mechanisms that constitute the initial events of receptor activation and signal transduction. Here, a comprehensive mechanistic view of agonist and antagonist action will be presented. Furthermore, the novel class of partial agonists-antagonists will be described and the multiple challenges and novel perspectives for nuclear-receptor-based drug design will be discussed.

[Cartography of absolute myocardial perfusion with magnetic resonance imaging. Methods and results]

Ultra-rapid dynamic MRI (one image per heart beat) can follow the progression of the intra-myocardial signal during the first passage of diffusable gadolinium chelates injected as a bolus through a peripheral vein. A quantitative evaluation of myocardial perfusion is possible using a compartmental model of analysis. Absolute myocardial flow can be measured at rest and during hyperaemia induced by dipyridamole. It is possible to associate functional mapping, corresponding to parametric images of the flow indices, to the global evaluation. The ratio between the values obtained during hyperaemia and under basal conditions correspond to the myocardial reserve. The principles, results and limitations of this method are discussed in the light of published results, underlining the advantages of absolute flow measurement and of the differences between the results of MRI and myocardial scintigraphy.

[Schnitzler syndrome: a rare cause of systemic urticaria]

INTRODUCTION

The Schnitzler's syndrome first described in 1972, associates urticaria, bone pain, and monoclonal IgM gammapathy.

EXEGESIS

A 50-year-old man presented symptoms of urticaria restricted to the trunk and lower members, with episodes of fever accompanied by inflammatory pain in the knees and legs. Slight deterioration of his general condition was also observed. Biological findings showed the existence of an inflammatory syndrome. Electrophoresis and immunoelectrophoresis provided evidence for the existence of underlying IgM gammapathy. Bone X-ray demonstrated the presence of tibial and peroneal metaphysis thickening, with hyperfixation on bone scintigraphy. The patient's condition improved after cortisone and colchicine treatment, allowing decrease in coricosteroid doses. Two years later, except for urticaria, clinical features have disappeared and no hematological disorder has been observed.

Myocardial bridging as a cause of acute transient left heart dysfunction

The significance of myocardial bridging is still a matter of debate, and although several reports have underlined its pathologic potential, myocardial bridging is often considered to be a benign phenomenon. We present here the case of a 63-year-old woman with a history of acute left heart failure and ECG evidence of ischemia, and whose primary abnormality on extensive workup was myocardial bridging. This case further underlines that myocardial bridging can lead to significant cardiac events.

Neurohormonal profile before and after beta-blockade in patients with neurocardiogenic syncope

Our objective was to evaluate the effects of beta-blockers on the neurohormonal profile, particularly vasopressin (VP) release, in vasovagal syncope and to gain further insight on the pathophysiology of this syndrome. Patients (< or =75 years) with no cardiovascular, neurological disorders, or contraindications to the use of isoproterenol or beta-blockers and being explored for unexplained syncope were included. An 80 degrees HUT was performed under identical conditions. After a 25-min period of passive tilt, isoproterenol was infused at a rate of 1-5 microg/mn if required. Two groups matched for age and sex were considered: a HUT-positive and a HUT-negative group. The HUT-positive group was then given beta-blockers, subsequently reassessed, and divided into two subgroups: alpha beta-blocker nonresponder group and a beta-blocker responder group. Blood samples for assays of norepinephrine (NE), epinephrine (E), and VP were taken at baseline and the end of the procedure. In all, 44 subjects entered the study, 22 in each group. The HUT-positive group exhibited an obvious lesser increase in plasma NE and a clear-cut rise in plasma E and VP compared to the HUT-negative group (P < 0.05). Even though no patient in the HUT-positive group reported recurrent symptoms under treatment, the second HUT could distinguish two subgroups: a beta-blocker nonresponder group (n = 12) whose HUT remained positive and a beta-blocker responder group (n = 10) whose HUT was normalized. The time course of plasma E and VP during the second HUT was similar to that for the HUT-positive and HUT-negative groups. In conclusion, the efficacy of beta-blockers is associated not only with a reduction of the sympathoadrenal stimulation seen in vasovagal syncope but also with a lower release of VP suggesting that low-pressure baroreceptors might be involved in VP release.

Modulation of lipid metabolism and spiramycin biosynthesis in Streptomyces ambofaciens unstable mutants

Streptomyces ambofaciens is prone to genetic instability involving genomic rearrangements at the extremities of the chromosomal DNA. An amplified DNA sequence (ADS205), including an open reading frame (orfPS), is responsible for the reversible loss of spiramycin production in the mutant strain NSA205 (ADS205(+) Spi-). The product of orfPS is homologous to polyketide synthase systems (PKSs) involved in the biosynthesis of erythromycin and rapamycin and is overexpressed in strain NSA205 compared with the parental strain RP181110. As PKSs and fatty acid synthase systems have the same precursors, we tested the possibility that overexpression of orfPS also affects lipid metabolism in strain NSA205. This report focuses on comparative analysis of lipids in strain RP181110, the mutant strain NSA205, and a derivative, NSA228 (ADS205(-) Spi+). NSA205 showed a dramatically depressed lipid content consisting predominantly of phospholipids and triacylglycerols. This lipid content was globally restored in strain NSA228, which had lost ADS205. Furthermore, strains RP181110 and NSA205 presented similar phospholipid and triacylglycerol compositions. No abnormal fatty acids were detected in NSA205.