Biomedical subjects

C Hardisson

Publications and source records attributed to C Hardisson.

86 records · Page 5Linked to original sources

PubMed1978

Early stages of arthrospore maturation in Streptomyces.

In the sporogenesis of Streptomyces, two basic stages can be considered: sporulation septum synthesis and arthrospore maturation. Most of the information about the ultrastructural changes accompanying the sporogenesis refer to the first stage of the process, but nothing has been published about the evolution of the sporulation septum during maturation. In a previous paper, proposed three basic types of sporulation septum formation in Streptomyces. Our ultrastructural study on the evolution of the sporulation septum during the early stages of arthrospore maturation in seven species of Streptomyces indicates correlation between the sporulation septum type and its evolution during the arthrospore maturation. In types I and II the material of the annuli was incorporated into the lateral walls of the arthrospore, whereas in types II and III the deposits were lysed during the maturation. Only in type III was the arthrospore wall synthesized de novo. In type I there was total integration and in type II there was partial integration of the septum into the arthrospore wall.

Microscopy, Electron↗

PubMed1977

The action of fosfomycin on the growth of Pseudomonas aeruginosa.

A study was made of the effect of the inoculum size and the culture conditions on the MIC of a strain of Pseudomonas aeruginosa that was sensitive to fosfomycin. The increase of the inoculum and the conditions which favour the cellular multiplication considerably increase the MIC. Phosphates inhibit the action of the antibiotic. Fosfomycin produces a logarithmic decrease in the number surviving 1 h after being added; the bacterial lysis measured by the decrease in the OD depends on the medium and is hardly noticeable in ordinary broth. In a minimum medium the antibiotic does not affect the growth. The determination of the variation in the consumption of oxygen is a rapid and accurate method of evaluating the effect of fosfomycin. A spontaneous mutant glpT was isolated which was more than 128 times more resistant than the isogenic parental strain. The growth curves of this mutant, the sensitive parental strain and a naturally resistant strain that was isolated in a patient were similar to each other in complex media. In synthetic media the naturally resistant strain shows shorter phases of latency, but the generation times are analogous. This would seem to indicate that the resistance to fosfomycin in P. aeruginosa has no influence on the speed of growth.

Anti-Bacterial Agents↗

PubMed1976

Ultrastructural studies of sporulation in Streptomyces.

This is the first study of sporogenesis in Streptomyces carried out on a relatively high number of species (seven) which allows us, using also previously published results, to establish a general picture of this process. In the sporogenesis of Streptomyces two basic stages can be considered: the sporulation septum synthesis and the arthrospore maturation. Our ultrastructural study of the sporulation septum formation suggests the existance within this genus of three basic types. Type I is distinguished because the septum is formed from the beginning by two separate cross walls. Within this type we include Streptomyces erythraeus, Streptomyces albus, and Streptomyces aureofaciens and also include Streptomyces venezuelae, Streptomyces griseus, and Streptomyces osteogriseus. Type II is distinguished because there is a deposit of material previous to the synthesis of the double annulus which completes the septum. This type can be divided into two subtypes. In the first the deposits are wedge-shaped and the double annulus is clearly visible, and to this group belong Streptomyces flaveolus, Streptomyces ambofaciens, and Streptomyces coelicolor. In the second the deposits, which have a different shape and are very well developed, constitute almost entirely the sporulation septum in which the double annulus is barely visible; Streptomyces antibioticus and also Streptomyces viridochromogenes belong to this group. Type III, represented by Streptomyces cinnamonensis, is distinguished because the septum is formed by a single cross wall.

Cell Wall↗

PubMed1969