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Biomedical subjects

M Barber

Publications and source records attributed to M Barber.

71 records · Page 4Linked to original sources
PubMed1979

Synthesis and biological activities of [7-(azetidine-2-carboxylic acid)]-oxytocin and -lysine-vasopressin.

[7-(Azetidine-2-carboxylic acid)]-oxytocin and -lysine-vasopressin have been synthesised by a (6 + 3) strategy using protected hexapeptide acids with preformed disulphide bridges, and their biological activities have been investigated. All activities were reduced but not to the same extent. In assays of pressor and antidiuretic activity it was observed consistently that the responses to the vasopressin analogue were of shorter duration than responses to lysine-vasopressin of the same amplitude.

Amino Acid Sequence↗
PubMed1969

Mass-spectrometric determination of the amino acid sequences in peptides isolated from the protein silk fibroin of Bombyx mori.

Several peptides were isolated from the protein silk fibroin of Bombyx mori by means of ion-exchange chromatography of a chymotryptic digest. The sequences of three of the peptides, Gly-Ala-Gly-Tyr, Gly-Val-Gly-Tyr and Gly-Ala-Gly-Ala-Gly-Ala-Gly-Tyr, were known from previous chemical work, but the sequence of the fourth, Gly-Ala-Gly-Val-Gly-Ala-Gly-Tyr, was previously only partially known. The necessary volatility for mass-spectrometric examination of the peptides was achieved by permethylation of the N-acetyl-peptide methyl ester derivatives. From the mass spectra it was possible to confirm the known sequences and to establish that of the partially known one. In one instance it was possible to deduce from the same mass spectrum the sequence of a main peptide component and that of a small amount of contaminating peptide. These results demonstrate for the first time the use of mass spectrometry in the determination of the amino acid sequences in peptides from a protein hydrolysate.

Amino Acid Sequence↗
PubMed1965

Drug combinations in antibacterial chemotherapy.

DOUBLE CHEMOTHERAPY FOR THE TREATMENT OF BACTERIAL INFECTIONS HAS BEEN RECOMMENDED FOR MANY REASONS, OF WHICH THE MOST IMPORTANT ARE THE FOLLOWING: (1) To achieve a synergic effect. (2) To delay the emergence of resistant strains. (3) To prevent superinfection. (4) To treat relatively inaccessible bacteria. (5) To treat mixed infections. (6) To treat undiagnosed infections.Combinations which have a truly synergic effect in vivo are those which show bactericidal synergy in vitro. Bactericidal therapy is of great practical importance in conditions which are inaccessible to the natural defences of the body, or where they are deficient. If in such cases the infecting bacterium is not readily killed by a single drug, then combinations should be tried. There are no absolute rules and double bactericidal sensitivity tests should always be carried out on the infecting strain, but the most likely combination to show this type of synergy is a penicillin and streptomycin.If a bactericidal drug is combined with an agent which is only bacteristatic, the killing effect may be antagonized, since many bactericidal drugs only kill rapidly multiplying cells. Again there are no absolute rules, but antagonism is particularly liable to occur when the bactericidal agent is one of the penicillins and is very unlikely to occur when it is a polymyxin, since this kills resting bacteria.Drug combinations to delay the emergence of drug-resistant strains should be considered for infections due to staphylococci and coliform bacilli, particularly in hospitals, and when it is desired to use drugs to which these bacteria readily develop resistance.Drug combinations may also be the most efficient treatment for mixed infections and may be necessary for the treatment of fulminating infections pending bacteriological diagnosis. The combination of nystatin with a tetracycline may be necessary to prevent candidiasis if tetracycline therapy has to be prolonged.

Anti-Bacterial Agents↗