Extracellular truncations of h beta c, the common signaling subunit for interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-5, lead to ligand-independent activation

The hypothesis that extracellular truncation of the common receptor subunit for interleukin-3 (IL-3), granulocyte-macrophage colony- stimulating factor, and IL-5 (h beta c) can lead to ligand-independent activation was tested by infecting factor-dependent hematopoietic cell lines with retroviruses encoding truncated forms of h beta c. A truncation, resembling that in v-Mpl, and retaining 45 h beta c-derived extracellular residues, led to constitutive activation in the murine myeloid cell line, FDC-P1. However, infection of cells with retrovirus encoding a more severely truncated receptor, retaining only 7 h beta c- derived extracellular residues, did not confer factor independence on these cells. These experiments show that truncation activates the receptor and define a 37-amino acid segment of h beta c (H395-A431) which contains two motifs conserved throughout the cytokine receptor superfamily (consensus Y/H XX R/Q VR and WSXWS), as essential for factor-independent signaling. The mechanism of activation was also investigated in less severe truncations. A receptor that retains the entire membrane-proximal domain (domain 4) also conferred factor independent growth on FDC-P1 cells; however, a retrovirus encoding a truncated form of h beta c having two intact membrane proximal domains did not have this ability, suggesting that domain 3 may have an inhibitory role in h beta c. The ability of these receptors to confer factor independence was cell specific as demonstrated by their inability to confer factor-independent growth when introduced into the murine IL-3-dependent pro-B cell line BaF-B03. These results are consistent with a model in which activation requires unmasking of an interactive receptor surface in domain 4 and association with a myeloid- specific receptor or accessory component. We suggest that in the absence of ligand intramolecular interactions prevent inappropriate signaling.     

B19 parvovirus replicates in circulating cells of acutely infected patients

B19 parvovirus is the etiologic agent of fifth disease and transient aplastic crisis. In natural infections, B19 antigen and DNA have been detected in sera early in the course of aplastic crisis and only rarely in fifth disease. We have found B19 DNA in circulating cells of infected patients by DNA dot blot with a virus-specific probe: in four of four sickle cell patients with aplastic crisis, in one asymptomatic sibling, and in one normal adult with fifth disease. Only two of the sera showed B19 DNA. High-molecular weight intermediate forms were detected by Southern analysis of DNA extracted from cells, thus indicating active replication of virus in cells rather than passive adsorption to their surface membranes. Separation of cells into high- and low-density fractions resulted in a concentration of the virus DNA in the granulocytic fraction.     

Role of adrenocortical scintigraphy in the exploration of incidentally discovered tumors]

To determine the utility of adrenocortical scintigraphy with I131-6 beta-iodomethyl-19-nor-cholesterol (NP59) in incidentally discovered adrenal masses, we studied 12 patients with a unilateral adrenal mass and without other primary tumors or signs of pheochromocytoma or hyperfunctioning adenoma. Ten patients had an adenoma (size: 12 to 35 mm), the diagnosis was made by surgery or by no change in size on repeated CT scans. The NP59 scintigraphy showed an increased uptake on the side of the tumor in 8 cases with a decreased uptake of contra-lateral gland in 7 cases. Hormonal investigations of glucocorticoid function suggested supranormal or fluctuant cortisol secretion in 5 cases as assessed by moderately elevated urinary free cortisol or by incomplete dexamethasone suppression test. These abnormalities disappeared after surgery. Two patients had normal bilateral uptake of NP59, the sizes of the tumors were 12 and 20 mm. Two patients had an extra-adrenal tumor. The NP59 scintigraphy showed a moderately decreased uptake on the side of the hematoma of one patient and a compression of the normal adrenal by ganglioneuroma of the other patient. Our results and those of other authors suggest that positive NP59 scintigraphy could confirm the cortical nature of an incidentally discovered adrenal mass, probably an adenoma that must be followed up morphologically and functionally. No uptake by a tumor greater than 2 cm suggests a primary malignancy or extra-adrenal origin which must be diagnosed by invasive methods.     

Eosinophil autofluorescence and its use in isolation and analysis of human eosinophils using flow microfluorometry

Unstained human eosinophils exhibit unusually bright autofluorescence, which allows them to be distinguished from other leukocytes using fluorescence microscopy. Eosinophil fluorescence is associated with the cytoplasmic granules of the cells. Eosinophil granule extracts, containing an as-yet-undefined eosinophil fluorescence factor, exhibited excitation maxima at 370 nm and 450 nm, with maximum emission at 520 nm. Eosinophils adhering to opsonized parasites in vitro deposit fluorescent material onto the parasite surface. Eosinophil fluorescence was of sufficient intensity to allow the preparation of viable, highly enriched (greater than or equal to 98%), eosinophil suspensions from peripheral blood of normal and eosinophilic donors using a fluorescence- activated cell sorter. Quantitative studies of eosinophil autofluorescence were performed using flow microfluorometry. Fluorescence intensity of blood eosinophils from normal volunteers and eosinophilic patients varied inversely with the log of the donor's absolute eosinophil count regardless of clinical diagnosis.     

Septic shock, multiple organ failure, and disseminated intravascular coagulation. Compared patterns of antithrombin III, protein C, and protein S deficiencies.

STUDY OBJECTIVE: Our aim was to document the following in patients with septic shock and disseminated intravascular coagulation (DIC): (1) the influence of DIC in the mortality rate and the occurrence of organ failure; (2) the comparative prognostic value of initial antithrombin III (ATIII), protein C (PC), and protein S (PS) levels; and (3) the compared pattern of sequential ATIII, PC, and PS levels according to clinical outcome. DESIGN: Demographic data, criteria of severity, mortality in ICU, frequency of organ failure, hemodynamic and oxygenation parameters, and laboratory findings were compared in patients with septic shock according to the occurrence of DIC. Initial and sequential levels of ATIII (activity), PC (antigen and activity), PS (total and free), and C4b binding protein (C4bBP) were compared according to the outcome in patients with DIC. PATIENTS: Sixty patients with septic shock were studied. Forty-four entered the group DIC+; 16 entered the group DIC-. RESULTS: Simplified acute physiologic score (SAPS), frequency of acquired organ failure, blood lactate, and transaminase values were significantly higher in the group DIC+. The mortality rate reached 77 percent in group DIC+ vs 32 percent in DIC- (p less than 0.001). In patients with DIC, a fatal outcome was associated with higher bilirubin and transaminase levels, lower PaO2/FIo2 ratio, Vo2, Do2 and O2 extraction. In the group DIC+, all patients but two had severe deficiencies in ATIII and PC levels. Significant correlations were found between initial ATIII and PC levels, PC and free PS levels, and free PS and C4bBP levels. Initial ATIII levels had the best prognostic value for prediction of subsequent death. Serial measurements were consistent with a prolonged ATIII and PC deficiency with significantly different levels between survivors and nonsurvivors. CONCLUSIONS: DIC is a strong predictor of death and multiple organ failure in patients with septic shock. Sequential ATIII, PC, and PS measurements were consistent with prolonged consumption or inhibition that might account for a sustained procoagulant state and inhibition of fibrinolysis. The initial ATIII level was the best laboratory predictor of death in these patients.     

New medical treatments in pituitary adenomas

Currently, the role of dopaminergic and somatostatinergic agonists in the treatment of pituitary adenomas is quite well established. Nevertheless, a clearer understanding of the expression of dopaminergic and somatostatinergic receptors at the cellular level of pituitary adenomas as well as the development of newer analogues compounds may drastically change current therapeutic modalities. In particular, the emphasis on the co-expression of different receptors types or subtypes in adenomatous cells highlights functional interactions between receptors leading to an increase in their activity. Newer molecules are also in the process of development : new somatostatin analogues with more universal binding properties to different receptors subtypes, as well as chimeric molecules capable of binding to somatostatinergic and dopaminergic receptors. In the midst of GH-secreting pituitary adenomas, a positive correlation exists between the expression of Sst2 mRNA and the inhibition of GH release by somatostatin analogues. The involvement of Sst5 subtype in adenomas resistant to preferential Sst2 agonists has recently been proved. Another recently developed compound has a more universal Sst binding profile. This compound, named SOM-230, has a 25, 5 and 40 times higher binding affinity to Sst1, Sst3 and Sst5 receptors respectively, and 2,5 times lower affinity to Sst2, when compared to octreotide. SOM-230 could therefore allow for much more effective methods in treating patients suffering from acromegaly. Besides, the use of a chimeric molecule presenting a binding affinity to both Sst2 and D2 subtypes (BIM-23A287) inhibits the secretion of GH in ways similar to the Sst2 or D2 agonists used alone or concurrently but however in a concentration 50 times lower than that of the latter. The discovery of Sst5 and D2 subtypes at the level of corticotropic adenomas reveals newer therapeutic perspectives with promising preliminary results with the use of SOM-230 ; these finding lead to a rise in interest in cabergoline. In the midst of non-functioning pituitary adenomas, the expression of Sst2, Sst3 and D2 receptors will perhaps allow the use of combined therapies associating the new somatostatin analogues to the dopaminergic agonists or even use dopastatin (BIM-23A760, chimeric molecule Sst2-Sst5-D2). The preliminary results obtained in vitro with this molecule are actually encouraging since they show a dose dependent inhibition of the cellular replication mechanisms in 60 % of the cases. Finally, concerning prolactinomas the discovery of Sst5 receptors lead to consider the use of somatostatinergic agonists specific to the Sst5 receptor, SOM-230 in particular. Nevertheless, it seems that adenomas resistant to dopaminergic agonist due to a lack of expression of D2 receptor fail to express Sst5 receptors as well. On the other hand, dopastatin appears to be more efficient than cabergoline in the management of this type of adenomas. Therefore, the growing awareness concerning the mechanisms involved in the control of pituitary secretions as well as cellular proliferation will perhaps allow physicians to treat the pathology of pituitary adenomas, macroadenomas in particular, using solely pharmacological means instead of invasive surgical procedures and/or radiotherapy.     

Meningococcal carriage during a clonal meningococcal B outbreak in France

The aim of this study performed in Normandy, France, was to analyze the pharyngeal meningococcal carriage at the peak of a clonal meningococcal B outbreak, which was subsequently controlled using an outer membrane vesicle vaccination. This cross-sectional study included randomly selected subjects aged 1–25 years. Carriers and non carriers were compared using unconditional logistic regression. Among the 3,522 volunteers, there were 196 (standardized rate: 6.46 %) Neisseria meningitidis carriers, of which there were only five with the outbreak strain (B:14:P1.7,16/ST-32; standardized rate: 0.18 %). From the multivariate analysis, older age, smoking, higher degree of socialization, and social deprivation appear to favor the carriage of all the strains included. Prior antibiotic treatment up to 12 months before swabbing, even with β-lactam, was protective against carriage. Our data indicate a low overall meningococcal carriage rate with a surprising protective effect of prior antibiotic exposure. The observed low carriage rate of the epidemic strain (B:14:P1.7,16/ST-32) contrasts with the high incidence of invasive meningococcal diseases (IMD) due to this strain. Hence, our data underline the high virulence of the strain and suggest a low level of natural immunity of the population against this strain. Although highly resource-consuming, carriage studies are helpful in guiding the implementation of control measures of IMD, such as mass vaccination or chemoprophylaxis.