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Biomedical subjects

J F Kennedy

Publications and source records attributed to J F Kennedy.

At least 91 records · Page 5Linked to original sources
PubMed1976

Active immobilized antibiotics based on metal hydroxides.

The water-insoluble hydroxides of zirconium (IV), titanium (IV), titanium (III), iron (II), vanadium (III), and tin (II) have been used to prepare insoluble derivatives of a cyclic peptide antibiotic by a facile chelation process. Testing of the antibacterial activities of the products against two gram-positive and two gram-negative bacteria showed that in the majority of cases the water-insoluble antibiotics remained active against those bacteria susceptible to the parent antibiotic. The power of the assay system has been extended by the novel use of colored organisms to aid determinations where the growth of normal organisms could not be distinguished from the appearance of the supporting material. Insoluble derivatives of neomycin, polymyxin B, streptomycin, ampicillin, penicillin G, and chloramphenicol were prepared by chelation with zirconium hydroxide, and these derivatives similarly reflected the antibacterial activities of the parent compounds. Several of the metal hydroxides themselves possess antibacterial activity due to complex formation with the bacteria. However, the use of selected metal hydroxides can afford a simple, inexpensive, and inert matrix for antibiotic immobilization, resulting in an antibacterial product that may possess slow-release properties. The mechanisms by which the metal hydroxide-antibiotic association-dissociation may occur are discussed.

Anti-Bacterial Agents↗
PubMed1975

Perfusion of human ovaries in vitro with artificial medium: metabolism and steroidogenesis.

A study was made of ovaries perfused in vitro with a liquid fluorocarbon that was stabilized in emulsion by a nonionic detergent to which tissue culture medium was added. A pulsatile flow was used in an organ preservation system under aseptic conditions. Glucose was utilized and lactate produced at a fairly constant rate for as long as 20 hours of perfusion. 14-C-progesterone and 14-C-17alphaOH-progesterone were synthesized from 14-C-acetate and estradiol was secreted. The production of these steroids by the perfused ovary appears to be responsive to gonadotropins.

Acetates↗
PubMed1975

Effects of titanium compounds on a D-glucose-D-glucose oxidase assay system.

Titanium compounds affect the measurement of D-glucose oxidase (and therefore D-glucose) by the D-glucose-D-glucose oxidase-peroxidase-2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) assay system. The validity of measurement of the activity of D-glucose oxidase immobilised on supports based on titanium oxides is affected by complexation of the intermediate hydrogen peroxide with the support, and such supports may prove to be unsuitable for the immobilisation of D-glucose oxidase. The formation of titanic peroxides is among the reasons discussed for the various interactions encountered. The use of the assay system for the determination of D-glucose oxidase contaminated with catalase and for the determination of hydrogen peroxide is also described.

Glucose Oxidase↗
PubMed1975

The use of cellulose xanthate for the immobilisation of biological molecules.

The mercapto groups of cellulose xanthate can reversibly form disulphide bridges with L-cysteine. This property has been utilised for the immobilisation of a protein and an enzyme. These macromolecules, as polythiol derivatives, formed disulphide linkages with the matrix without serious disturbance of their active sites, became firmly bound to the xanthate, and were not eluted by normal washing conditions. Cellulose xanthate is a cheap, easily prepared matrix which permits a simple coupling reaction. The immobilisation process is selectively reversible.

Binding Sites↗
PubMed1975

Evidence for the inactivation of an X chromosome early in the development of the human female.

Studies of somatic tissues and cultured cells, including fibroblast clones, from human embryos heterozygous for the electrophoretic variants of glucose-6-phosphate dehydrogenase confirm that one X chromosome is inactivated very early in embryonic development and indicate that X inactivation has occurred in the majority of cells from a variety of tissues at least by 5 weeks from conception.

Blood Protein Electrophoresis↗
PubMed1974

Active insolubilized antibiotics based on cellulose-metal chelates.

Cellulose was converted into a more reactive form by chelation with the transition metals titanium(III), iron(III), tin(IV), vanadium(III), and zirconium(IV). The remaining unsubstituted ligands of the transition metal ions were found to be amenable to replacement by electron-donating groups of antibiotic molecules. Ampicillin, gentamicin, kanamycin, neomycin, paromomycin, polymyxin B, and streptomycin were used as antibacterial antibiotics, and amphotericin B and natamycin were used as antifungal antibiotics. Antibacterial activity of the products was tested against two gram-positive and two gram-negative bacteria, and antifungal activity was tested against four fungi. That the antibacterial antibiotics had complexed with the cellulose-metal chelates was demonstrated in that the product cellulose-metal-antibiotic chelates exhibited antibiotic activities whereas the metal chelates of cellulose themselves were inactive. Of 140 tests conducted, cellulose-metal-antibiotic chelates were active in 102 cases. Since the antibiotic derivatives were water insoluble and in fact retain some of the antibacterial activities of the parent compounds, the chelation method provides a facile way of rendering cellulose surfaces, etc., resistant to microbial attack over and above that degree of protection afforded by noncovalent adsorption of the antibiotic to cellulose itself. The underlying principles of the chelation reactions involved are discussed in detail.

Anti-Bacterial Agents↗