A High Order Iterative Scheme for a Nonlinear Kirchhoff Wave Equation in the Unit Membrane

A high-order iterative scheme is established in order to get a convergent sequence at a rate of orderN(N≥1) to a local unique weak solution of a nonlinear Kirchhoff wave equation in the unit membrane. This extends a recent result in (EJDE, 2005, No. 138) where a recurrent sequence converges at a rate of order 2.

Megalencephalic Leukoencephalopathy with Subcortical Cysts: A Third Confirmed Case with Literature Review

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) causes early-onset, slowly progressive central nervous system white matter disease, macrocephaly, and later cognitive and motor decline. We describe brain structure in a patient with MLC and proven MLC1 mutations. A male, normal at birth, had macrocephaly at 6 months followed by developmental delay. Magnetic resonance imaging showed extensive signal abnormality in cerebral white matter and subcortical progressive cystic changes in the bilateral temporal and right frontal areas. Biopsy of frontal gyrus at age 15 months showed normal gray matter. The subcortical white matter was pale due to prominent fine uniform 2- to 4-μ-thick vacuoles with a few interspersed myelinated axons and rare microglia. The vacuoles had a single-, double-, or, rarely, triple-unit membrane (resembling myelin) and contained occasional organelles but no intermediate filaments. Both normal myelinated and thinly myelinated axons were observed. The outer and occasionally the inner layers of myelin surrounding intact axons formed blebs that may represent a source for vacuoles. Genetic analysis identified 2 heterozygous mutations of intron 3 (c.322–1 G>A) and intron 7 (c.597+1G>A), the 1st leading to deletion of amino acids 60 to 89 and the 2nd to deletion of amino acids 194 to 199. Fine uniform vacuolation of white matter with wide separation of myelinated axons is the hallmark of MLC in early childhood.

Na+-K+-ATPase is distributed to microvillous and basal membrane of the syncytiotrophoblast in human placenta

Despite its importance for placental function, syncytiotrophoblast Na+-K+-ATPase has not been studied in detail. We purified syncytiotrophoblast microvillous (MVM) and basal (BM) membranes from full-term human placenta. Western blotting with isoform-specific antibodies demonstrated the presence of the α1-subunit, but not the α2- or α3-subunits, in MVM and BM. Relative density per unit membrane protein in BM was 48 ± 1% (mean ± SE, n = 4, P < 0.02) of that in the MVM. The activity of Na+-K+-ATPase was lower in BM (1.4 ± 0.14 μmol · mg−1· min−1, n = 8, P < 0.02) than in MVM (3.9 ± 0.25 μmol · mg−1· min−1). Immunocytochemistry confirmed the distribution of Na+-K+-ATPase to MVM and BM. These findings suggest that the syncytiotrophoblast represents a type of transporting epithelium different from the classical epithelia found in the small intestine and kidney, where Na+-K+-ATPase is confined to the basolateral membrane only. This unique polarization of the Na+pump does not, however, preclude a net transcellular transport of Na+to the fetus.

Fisiologie en patofisiologie van selorganelle

Lysosomes are found in the cytoplasm of all eucaryotic cells except mature red blood cells. The matrix of the organelle is separated from the surrounding cytoplasm by a trilaminar unit membrane and contains a variety of acid hydrolytic enzymes. Morphologically primary (recently formed from the Golgi-complex) are distinguished from secondary lysosomes. The latter type is formed after fusion of a vacuole with a primary lysosome and is ultrastructurally extremely heterogeneous due to the large variety of substrates (macro­ molecules ) incorporated in the matrix of the organelle. The acid hydrolases of lysosomes are divided into the following five groups: phosphatases, nucleases, polysaccharide- and glycosaminoglycans (GAG)-liydrolases, proteases and lipases.

Effect of lactation on insulin signal transduction in sheep adipose tissue and skeletal muscle

The molecular basis of the insulin resistance of adipocytes and skeletal muscle during lactation has been investigated in sheep. The number of insulin receptors per adipocyte or per unit membrane protein for skeletal muscle is unchanged by lactation. The ability of insulin to stimulate autophosphorylation of its β-subunit was enhanced in adipocytes but not in skeletal muscle during lactation. This increased autophosphorylation was due, at least in part, to enhanced tyrosine phosphorylation and was found when both solubilised, immunoprecipitated insulin receptors and intact adipocytes were incubated with insulin. The ability of the insulin receptor kinase to phosphorylate other proteins did not appear to be altered by lactation; this was shown with lectin-purified insulin receptors using the artificial substrate, polyglutamyl tyrosine, and in intact adipocytes. Lactation had no effect on the ability of insulin to activate two key downstream kinases, mitogenactivated protein kinase and phosphatidyl inositol-3-kinase in adipocytes. The study thus shows that the insulin resistance of lactation in sheep is due to changes downstream of the receptor in both adipocytes and skeletal muscle. Journal of Endocrinology (1996) 151, 469–480