XYY chromosomal complement,proven by fluorescence,in a child with trisomy 21: 48,XYY,21+

Summary Clinical, cytogenetic, autoradiographic, fluorescence microscopic and dermatoglyphic data of a boy with 48,XYY,21+ karyotype are reported. The child had some clinical anomalies common in Down's syndrome. DNA replication of the 2 Y chromosomes was synchronous in all labelled metaphases. It was possible to distinguish the two Y's from the pairs No. 21-22 under the fluorescence microscope and single as well as double Y bodies were demonstrated in buccal mucosa cells. Dermatoglyphic investigation revealed some features typical for mongolism.     

Copper organo-chelators inAspergillus fumigatus andPenicillium chrysogenum

The presence of copper in the growth medium induces the biosynthesis of several low-mol-wt copper ogano-chelators in Aspergillus fumigatus and Penicillium chrysogenum. By use of P. chrysogenum, we were able to prepare several low-mol-wt metallothionein chelators, as well as several short-chain copper chelatins. The amino acid composition of a chelatin of mol wt approx 799 Da revealed the presence of cysteine, glutamic acid, glycine, and leucine. Use of A. fumigatus led to fewer copper chelators and one very short-chain peptide: a chelatin of mol wt approx 624 Da. composed of four amino acids, asparagine, glutamic acid, cysteine, and glycine. These results may confirm our assumption that fungi detoxify the deleterious action of toxic elements by producing high levels of heavy metal chelators/chelatins.     

Regulatory Mutations Affecting the Gluconate System in Escherichia coli

A spontaneously arising regulatory mutant of the gluconate system in Escherichia coli was isolated. This mutant became constitutive, probably in one step, for gluconate high-affinity transport, gluconokinase, and gluconate-6-P dehydrase. The mutation involved (gntR18) is cotransducible with asd. Pseudorevertants, derived from a mutant (M2) that shows a long lag for growth on gluconate mineral medium, were also isolated and characterized. They give constitutive levels of gluconokinase and gluconate-6-P dehydrase but lack high-affinity transport function. Genetic experiments performed with one of these pseudorevertants (M4) indicate that it carries a secondary mutation in the gntR gene. The M4 phenotype is thus the result of the interaction of expression of a constitutive mutation (gntR4) with the mutation of strain M2 (gntM2).     

Vellozone,a tetracyclic triterpene from Vellozia stipitata

The isolation of (20R)-20-hydroxy-24-methylenedammar-3-one from Vellozia stipitata is described.     

Rheological properties of cross-linked hyaluronan-gelatin hydrogels for tissue engineering

Hydrogels that mimic the natural extracellular matrix (ECM) are used in three-dimensional cell culture, cell therapy, and tissue engineering. A semi-synthetic ECM based on cross-linked hyaluronana offers experimental control of both composition and gel stiffness. The mechanical properties of the ECM in part determine the ultimate cell phenotype. We now describe a rheological study of synthetic ECM hydrogels with storage shear moduli that span three orders of magnitude, from 11 to 3 500 Pa, a range important for engineering of soft tissues. The concentration of the chemically modified HA and the cross-linking density were the main determinants of gel stiffness. Increase in the ratio of thiol-modified gelatin reduced gel stiffness by diluting the effective concentration of the HA component.     

Metal complexes of bovine lactoferrin inhibit in vitro replication of herpes simplex virus type 1 and 2

The inhibitory effect of bovine lactoferrin (BLf) saturated with ferric, manganese or zinc ions, on the infection of Vero cells by human herpes simplex virus type 1 (HSV1) and 2 (HSV2) was investigated. Viral infectivity determined by intracellular antigen synthesis and plaque formation was efficiently inhibited by metal saturated lactoferrins in a dose-dependent manner. Effective BLf concentrations which reduced the infection by 50% ranged from 5.2 to 31 mug ml and were far below the cytotoxicity threshold. Fe BLf and Mn BLf exhibited selectivity indexes higher than Zn BLf and apoBLf for both viruses and the effect was mainly directed towards the early steps of infection. The slight viral inhibition shown by the citrate complexes of the different metals could indicate that the antiviral effect was not significantly influenced by Fe , Mn or Zn ions delivered by BLf into the cells. © Rapid Science 1998     

Development of a multispecies periodontal biofilm model within a stirred bioreactor

Abstract

The objective of this work was to develop a subgingival biofilm model using a stirred bioreactor. Discs of bovine teeth were adapted to a stirred bioreactor filled with a culture medium containing bacterial species associated with periodontal health or disease. After anaerobic incubation, the biofilms growing on the substratum surfaces were collected and analyzed. The mean number of Colony-forming Units (CFUs) varied, but with no difference between 3 and 7?days of biofilm formation (p?>?0.05). Scanning Electron Microscopy (SEM) analysis showed a uniform biofilm layer covering the cement layer of the root surface containing bacteria with diverse morphology. In checkerboard DNA-DNA hybridization, bacterial species were identified in both biofilms. In conclusion, a subgingival biofilm model was developed using a stirred bioreactor, allowing the in vitro reproduction of complex microbial communities. This is an advanced model that may be useful to mimic complex clinical periodontal biofilms.