Presence de Chitinozoaires dans les calcaires siluro-devoniens de la Sierra Negra (Pyrenees centrales espagnoles)

A stratigraphical and paleontological study of the Silurian in the Benasque area of the high Pyrenees has made it possible to assign an Upper Pridolian age to certain limestones which occur near the top of a thick and monotonous serie of black shales. These limestones yeiled some remarkably well preserved chitinozoa together with some conodonts, orthocerases and pelecypods.     

Scabies masquerading as Letterer-Siwe's disease.

Letterer-Siwe''s disease was diagnosed from clinical appearance and initial assessment of a skin biopsy in a child with a 2-month history of skin rash. Fine erythematous papules were scattered on the trunk. The biopsy showed epidermal thickening and an inflammatory infiltrate chiefly in the upper layers of the dermis; deeper in the dermis the infiltrate was perivascular and periappendicular, histiocytes predominating in some areas and lymphocytes in others. A diagnosis of scabies was made after burrows were demonstrated on palms and soles and the mite of scabies was isolated from them.     

Electronmicroscopy studies on the exocrine pancreas of Wistar-Rats following treatment with Streptozotocin.

In Wistar rats the intraveneous injection of streptozotocin (65 mg/kg body weight) caused a permanent hyperglycemia. After 5 days there were lesions in the exocrine parenchyme of the pancreas and its nerve fibers. Pathological changes were found in cytoplasm, cell membrane, nucleus and all other cell organelles, too. The zymogen granules remaining after extensive degranulation may disintegrate in two different ways: 1. Shrinking of the granules and formation of a hale between granule membrane and core, the electronic density of which is decreased; indistinct demonstrability of the granule membrane and finally its decomposition. 2. Shrinking of the granules, decrease of the electron density and either homogeneous or mainly peripheral arrangement of the disintegrated material of the granules; irregular shape of the granules and splitting of their membranes.     

The role of cytosolic free calcium in the generation of inositol 1,4,5-trisphosphate and inositol 1,3,4-trisphosphate in HL-60 cells. Differential effects of chemotactic peptide receptor stimulation at distinct Ca2+ levels

The generation of the two inositol trisphosphate (IP3) isomers, 1,4,5-IP3 and 1,3,4-IP3, and its relation to changes in the cytosolic free calcium concentration, [Ca2+]i, in response to the chemotactic peptide fMet-Leu-Phe was studied in the human promyelocytic cell line HL-60, induced to differentiate with dimethyl sulfoxide. Stimulation by fMet-Leu-Phe within seconds transiently elevates 1,4,5-IP3 to peak values averaging 8-fold basal levels, and leads to a concomitant rise in [Ca2+]i and to degranulation. These responses are followed by a slower and more sustained rise in 1,3,4-IP3. Alterations in [Ca2+]i modulate differentially the generation of the two IP3 isomers. At [Ca2+]i lower than 30 nM, no IP3 is generated upon fMet-Leu-Phe stimulation. Working at normal resting [Ca2+]i, but preventing the fMet-Leu-Phe induced transient rise in [Ca2+]i (by prior depletion of intracellular Ca2+ stores and working in calcium-free medium) the fMet-Leu-Phe stimulation of 1,3,4-IP3 levels is attenuated, whereas the response of 1,4,5-IP3 is not significantly altered. Maintained elevation of [Ca2+]i to micromolar levels with the Ca2+ ionophore ionomycin generates enhanced 1,3,4-IP3 levels in the absence of fMet-Leu-Phe, whereas the fMet-Leu-Phe stimulation of 1,4,5-IP3 generation is markedly inhibited. Pertussis toxin selectively abolishes the fMet-Leu-Phe-induced IP3 production, whereas ionomycin stimulation of 1,3,4-IP3 generation is unaffected. These findings indicate that in intact cells: receptor-triggered phosphatidylinositol bisphosphate phosphodiesterase activation has a minimal Ca2+ requirement, but does not depend on a previous or concomitant rise in [Ca2+]i; Ca2+ elevations above micromolar levels decrease the fMet-Leu-Phe-induced generation of 1,4,5-IP3; and 1,3,4-IP3 generation is not directly linked to receptor activation and appears to result both from increased [Ca2+]i and 1,4,5-IP3 levels.     

Multi-organ, multi-lineage engraftment by a single bone marrow-derived stem cell

Purification of rare hematopoietic stem cell(s) (HSC) to homogeneity is required to study their self-renewal, differentiation, phenotype, and homing. Long-term repopulation (LTR) of irradiated hosts and serial transplantation to secondary hosts represent the gold standard for demonstrating self-renewal and differentiation, the defining properties of HSC. We show that rare cells that home to bone marrow can LTR primary and secondary recipients. During the homing, CD34 and SCA-1 expression increases uniquely on cells that home to marrow. These adult bone marrow cells have tremendous differentiative capacity as they can also differentiate into epithelial cells of the liver, lung, GI tract, and skin. This finding may contribute to clinical treatment of genetic disease or tissue repair.     

Microwave exposure alters the expression of 2-5A-dependent RNase

The effects of 2.45-GHz continuous-wave microwaves (SAR = 130 mW/g) on the expression of the interferon-regulated enzymes 2'-5'-oligoadenylate (2-5A) synthetase(s) and 2-5A-dependent endoribonuclease (RNase L) were studied in murine L929 cells. Cells growing as monolayers were removed from the substratum and placed in suspension culture for a 4-h sham or microwave exposure. The cells were returned to monolayer growth for 18 h, and then harvested and assayed to determine the amount of RNase L protein (via [32P]2-5A binding) and the specific activities of RNase L and 2-5A synthetase. Binding of radioactive 2-5A to RNase L for sham- and microwave-exposed samples was 14.5 and 36.4% above control, respectively (the microwave-exposed bound 19.0% more probe than the sham-exposed). The increases in 2-5A binding were accompanied by corresponding elevations of RNase L specific activity. In contrast, sham or microwave irradiation produced no alterations in 2-5A synthetase specific activity. No detectable differences were noted in the postexposure cell viability, plating efficiency, or proliferation rate. Also, there were no detectable differences in cell viability or plating efficiency between controls and cultures irradiated for 2 h when the temperature was simultaneously increased to above normal physiological limits (39 to 45 degrees C). The SAR (130 mW/g) and the power density (95 mW/cm2) used for the greater part of this study were nearly 20 times higher than the ANSI limit of 8 mW/g and 5 mW/cm2 for any 1 g of exposed human tissue.