Effect of Niobium Oxide on the Structure and Properties of Melt‐Derived Bioactive Glasses

The effects of adding Nb₂O₅ on the physical properties and glass structure of two glass series derived from the 45S5 Bioglass^® have been studied. The multinuclear ²⁹Si, ³¹P, and ²³Na solid‐state MAS NMR spectra of the glasses, Raman spectroscopy and the determination of some physical properties have generated insight into the structure of the glasses. The ²⁹Si MAS NMR spectra suggest that Nb⁵⁺ ions create cross‐links between several oxygen sites, breaking Si–O–Si bonds to form a range of polyhedra [Nb(OM)_6?y(OSi)_y], where 1 ≤ y ≤ 5 and M = Na, Ca, or P. The Raman spectra show that the Nb–O–P bonds would occur in the terminal sites. Adding Nb₂O₅ significantly increases the density and the stability against devitrification, as indicated by ΔT(T_x ? T_g). Bioglass particle dispersions prepared by incorporating up to 1.3 mol% Nb₂O₅ by replacing P₂O₅ or up to 1.0 mol% Nb₂O₅ by replacing SiO₂ in 45S5 Bioglass^® using deionized water or solutions buffered with HEPES showed a significant increase in the pH during the early steps of the reaction, compared using the rate and magnitude during the earliest stages of BG45S5 dissolution.     

Abnormalities in the p34cdc2-related PITSLRE protein kinase gene complex (CDC2L) on chromosome band 1p36 in melanoma

Recently, several clusters of hepatitis A have been observed among hemophiliacs linked to factor VIII concentrates treated for virus inactivation solely with the solvent/detergent (S/D) method, a procedure that does not affect nonenveloped viruses such as the hepatitis A virus (HAV). A new outbreak of hepatitis A in six hemophiliacs treated with the same lot of a factor VIII preparation occurred recently in Germany. The objective of the study was to clarify whether these diseases were caused by the administration of the S/D-treated plasma product, rather than a community-acquired infection. Polymerase chain reactions designed to detect HAV nucleic acid have been carried out in the implicated factor VIII lots, in the corresponding plasma pools, and in serum samples of four out of six infected individuals. The nucleic acid sequences were determined in samples that resulted in positive amplification products. HAV sequences were found in one of the two plasma pools used for manufacture of the incriminated product, in the incriminated lot itself, and in all recipient sera tested so far, although the latter were collected up to 7 weeks after the onset of jaundice. The sequences obtained were completely identical, revealing a unique HAV strain of genotype IA. This study provides conclusive evidence that hepatitis A can be transmitted by factor VIII concentrates treated solely by the S/D procedure for virus inactivation. This inactivation method is not effective against nonenveloped viruses. Since a number of hepatitis A transmission episodes have been described with such preparations during the past 10 years, their continued use seems to be questionable unless additional virus removal or inactivation steps are introduced to prevent the transmission of nonenveloped viruses. Molecular approaches again proved to be reliable tools for elucidating the chain of virus transmission.     

Crucial role of FcgammaRIIa (CD32) in assessment of functional anti-Streptococcus pneumoniae antibody activity in human sera

Immunoglobulin G (IgG)-mediated phagocytosis by polymorphonuclear leukocytes (PMNL) constitutes the main defense against Streptococcus pneumoniae. Two leukocyte IgG receptors, FcgammaRIIa and FcgammaRIIIb, are constitutively expressed on PMNL. Blocking experiments showed FcgammaRIIa is crucial for opsonophagocytosis of serum-opsonized S. pneumoniae. The biallelic, genetically determined FcgammaRIIa polymorphism (FcgammaRIIa-R131 vs. IIa-H131) determines the capacity of IgG2-mediated phagocytosis via this receptor. Comparative studies with PMNL from donors either homozygous for FcgammaRIIa-R131 or IIa-H131 showed the latter had higher phagocytic capacity. These results were confirmed in FcgammaRIIa-R131- and FcgammaRIIa-H131-transfected IIA1.6 cells. The performance of FcgammaRIIa-transfected cells in S. pneumoniae phagocytosis was validated using sera from adults and children. Serum-induced phagocytic activity depended mainly on anti-pneumococcal IgG2 antibodies. Results obtained with PMNL and IIA1.6 cells showed high correlation (r=0.94; P<.001), and support that FcgammaRIIa transfectants are a good alternative to PMNL as effector cells in opsonophagocytosis assays.     

Histochemical study of magellanic penguin (Spheniscus magellanicus) minor salivary glands during postnatal growth

The histological and histochemical features of the minor salivary glands during postnatal development have been generally associated with the type of food ingested. However, recent studies support the fact that these salivary glands develop independently of the diet; in fact, minor salivary glands have similar morphological and histochemical characteristics in adult individuals of species with different diet regimens. Thus, the aim of this study was to characterize the developmental morphology of the penguin minor salivary glands and to contrast them with minor salivary glands of other species. The tongue, palatine, and mouth cavity (bottom) minor salivary glands of newborn, 1- to 20-day-old, and adult magellanic penguins were studied with hematoxylin-eosin, periodic acid-Schiff, alcian blue, toluidine blue, and lectin histochemistry. Minor salivary glands were present at all ages, although they were only moderately developed in animals less than 15 days old. After this age, glands were abundant in all age groups; in addition, cells from the glandular epithelium were functionally mature and secreted mucins. Nevertheless, in newborn to 15-day-old penguins, mucins were located only at the apical cytoplasm of mucous cells. In all ages, mucous cells displayed periodic acid-Schiff-positive, alcianophilic, and metachromatic reactions; among mucous cells, other orthochromatic cells appeared interspersed. From 15 days on, histochemical reactions became more intense until adulthood, and the cytoplasm of secretory cells was filled with glycoproteins and sulfomucins. Moreover, lectins bound to different oligosaccharides in mucous cells, depending on the stage of maturation of the glands. In conclusion, penguin minor salivary glands are already present at birth, and show progressive and quantitative increases in mucous secretion during postnatal development. These changes are necessary not only for nutrient ingestion, but also for nonimmune protection of the buccal cavity.     

Can retrograde cardioplegia alone provide adequate protection for cardiac valve surgery?

Pretreatment of rats with the extract of Ginkgo biloba termed EGb761 reduced the behavioral sensitization induced by successive D-amphetamine administrations (0.5 mg/kg) as estimated by increasing values of locomotor activity. EGb761 pretreatment also prevented the reduced density of [3H]dexamethasone binding sites in the dentate gyrus and the CA1 hippocampal regions of D-amphetamine treated animals. These observations suggest that EGb761, by reducing glucocorticoid levels, could modulate the activity of the neuronal systems involved in the expression of the behavioral sensitization.