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.     

Photoinhibition at chilling temperature

The effects of moderate light at chilling temperature on the photosynthesis of unhardened (acclimated to +18° C) and hardened (cold-acclimated) spinach (Spinacea oleracea L.) leaves were studied by means of fluorescence-induction measurements at 20° C and 77K and by determination of quantum yield of O₂ evolution. Exposure to 550 mol photons·m^-2·s^-1 at +4° C induced a strong photoinhibition in the unhardened leaves within a few hours. Photoinhibition manifested by a decline in quantum yield was characterized by an increase in initial fluorescence (F _o) and a decrease in variable fluorescence (F _v) and in the ratio of variable to maximum fluorescence (F _V/F _M), both at 77K and 20° C. The decline in quantum yield was more closely related to the decrease in the F _V/F _M ratio measured at 20° C, as compared with F _V/F _M at 77K. Quenching of the variable fluorescence of photosystem II was accompanied by a decline in photosystem-I fluorescence at 77K, indicating increased thermal de-excitation of pigments as the main consequence of the light treatment. All these changes detected in fluorescence parameters as well as in the quantum yield of O₂ evolution were fully reversible within 1–3 h at a higher temperature in low light. The fast recovery led us to the view that this photoinhibition represents a regulatory mechanism protecting the photosynthetic apparatus from the adverse effects of excess light by increasing thermal energy dissipation. Long-term cold acclimation probably enforces other protective mechanisms, as the hardened leaves were insensitive to the same light treatment that induced strong inhibition of photosynthesis in unhardened leaves.Abbreviations F ₀ initial fluorescence - F _M maximum fluorescence - F _V variable fluorescence (F _M-F ₀ - PFD photon flux density - PS photosystem     

Ichnology and sedimentology of a tide‐influenced delta in the Ordovician from the northeastern Alborz range of Iran (Kopet Dagh region)

The Middle–Late Ordovician Ghelli Formation in the Kopet Dagh region northeastern Alborz range of Iran is composed of siliciclastic rocks deposited in a variety of turbidite to marginal marine environments (deep marine clastic fan and related environments and prodelta, distal delta front, proximal delta front and distributary channels). The ichnology of the middle member of the Ghelli Formation is here reported. Combined sedimentological and ichnological analysis allows recognition of a tide‐influenced deltaic succession in the middle member of the Ghelli Formation consisting of three main facies associations: lower distributary channels, delta front and prodelta facies. Twenty‐two ichnogenera have been identified in this marginal marine succession: Arenicolites, Arthrophycus, Bergaueria, Chondrites, Conichnus, Cruziana, Cylindrichnus, Didymaulichnus, Diplichnites, Diplocraterion, Helminthopsis, Gyrochorte, Lockeia, Macaronichnus, Monomorphichnus, Palaeophycus, Planolites, Rosselia, Rusophcus, Skolithos, Teichichnus and ?Scolicia. Their distribution is clearly linked with lithofacies and depositional palaeoenvironments. The ichnological analysis reveals that the trace fossil suites developed in these environments indicate low diversity and low to moderate abundance of burrows, poor development of tiering and sporadic distribution. Low ichnodiversity and low bioturbation intensities with higher bioturbation clusters consist of facies‐crossing ichnogenera, and the impoverishment of suspension‐feeding trophic types indicates ‘stressed’, non‐archetypal expression of the Cruziana ichnofacies. The periodic higher intensities of bioturbation due to variations in hydrodynamic regimes of tidal currents reflect the archetypal of the Cruziana ichnofacies (and rare Skolithos ichnofacies).     

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.     

Molecular basis for cytadsorption of Mycoplasma pneumoniae.

Hemadsorbing (HA+) virulent Mycoplasma pneumoniae and spontaneously derived nonhemadsorbing (HA-) avirulent mutants were compared by biochemical and ultrastructural techniques in an attempt to understand the molecular basis for cytadsorption. Lactoperoxidase-catalyzed iodination of intact mycoplasmas indicated that both virulent and avirulent mycoplasmas displayed similar surface protein patterns. A specific external protein, P1 (molecular weight, 165,000), previously implicated as a major ligand mediating attachment, was readily detected in HA+ and HA- mycoplasma strains. However, immunoferritin electron microscopy, with monospecific antibody against P1, revealed that differences in P1 topography existed among these strains. Only virulent mycoplasmas exhibited high concentrations of P1 at the terminal organelle. Avirulent mycoplasmas which possessed P1 showed no P1 clustering at the terminus. Both virulent M. pneumoniae and avirulent P1-containing mutants possessed numerous less dense P1 regions along the mycoplasma surface. Not surprisingly, an HA- mutant lacking P1 exhibited only background immunoferritin labeling. Negative staining of intact mycoplasmas revealed a well-defined, naplike terminus (associated with P1 clusters) confined at the tip of virulent M. pneumoniae. Previous characterization of HA+ virulent and HA- avirulent strains of M. pneumoniae by one- and two-dimensional polyacrylamide gel electrophoresis suggests that identified groups of mycoplasma proteins, lacking in specific HA- mycoplasmas, regulate the physical arrangement of P1 and the ultrastructure of the terminus, thus influencing adherence to the respiratory epithelium and virulence.