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.     

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.     

First results of a study on airborne sporomorps in Budapest,Hungary

The first results of an aerobiological study, with the help of a Burkard spore trap in Hungary, are reported. A pollen calendar of 1989 is presented. Out of the total identified sporomorphs, the most relevant 16 types of pollen and 10 of fungal spores are reported. We have pointed out, that in Budapest Ambrosia and Artemisia pollen and some fungal spores are particularly responsible for the long lasting allergies to pollen and spores in the autumn. The pollen frequencies and the symptom scores of patients of the Pediatrics (Semmelweis Medical School, Budapest) showed a good correlation. Weekly reports are published in a newspaper and in television.     

Selectivity of different biological products to the egg parasitoid Telenomus remus (Hymenoptera: Platygastridae)

The selectivity of five entomopathogens and a chemical insecticide (positive control) to pupae and adults of the egg parasitoid Telenomus remus (Nixon) was evaluated in the laboratory under controlled environmental conditions according to protocols established by the International Organization for Biological Control. Baculovirus anticarsia (Baculovirus AEE^®), Bacillus thuringiensis var. kurstaki (Thuricide^®), Bacillus thuringiensis var. aizawai (Agree^®), Beauveria bassiana (Boveril^®), Metarhizium anisopliae (Metarril^®) and Trichoderma harzianum (Trichodermil^®) are harmless to T. remus pupae, and adults. Thus, our results suggest that the insect control strategies applied here are compatible since entomopathogens were classified as harmless to T. remus in most examined cases and therefore facilitate a joint application to control different pests. Bacillus thuringiensis var. kurstaki (Dipel^®), despite being classified as slightly harmful in some of the evaluations, can still be considered compatible for use together with T. remus, especially when compared with chemical insecticides such as chlorpyrifos that might be considered harmful to the parasitoid survival.