Search PubMed⌕ Search

Biomedical subjects

A Horvath

Publications and source records attributed to A Horvath.

68 records · Page 4Linked to original sources
PubMed1982

Peptide antagonists of LH-RH: large increases in antiovulatory activities produced by basic D-amino acids in the six position.

It has been assumed, usually with good reason, that D-amino acids with large aromatic side-chains must be present in position 6 of both LH-RH superagonists and antagonists for the highest levels of biological activity to be reached. However, using one of a recent generation of potent lH-RH inhibitory analogs as a model, we have found that the insertion of D-lysine or, better still, D-arginine in this position results in greater antiovulatory activity in the rat over corresponding D-phenylalanine6- and D-tryptophan6-analogs. For instance, [Ac-D-p-Cl-Phe1,2,D-Trp3,D-Arg6,D-Ala10]-LH-RH exhibits antiovulatory activity at a dose of 750 ng per animal and appears to be the first competitive antagonist with activity in the nanogram region in vivo. This effect seems to be highly dependent on the degree of basicity of the amino acid side-chain since D-amino acids with neutral or acidic groups produced far less active compounds.

Animals↗
PubMed1981

Staining of collagen and elastin in tissue slices with the methyl-benzothiazol-2-on-hydrazone reagent.

Collagen and elastic fibres were stained in cryostatic slices of various tissues with the MBTH reaction, specific for aldehyde groups. Depending on the source, collagen and elastin gave different colours, easy to distinguish. It appears that this simple technique could be useful not only to visualize cross-linking in vivo of these fibres but also to explore their pathological alterations.

Animals↗
PubMed1979

Children who wear individual hearing aids in British Columbia, Canada.

Data collected on the use of hearing aids by 680 school-aged hearing-impaired subjects are examined and aid use is related to gender, age, hearing loss, age at onset, aetiology, age at diagnosis, educational setting, method of communication, primary language in the home, hearing status of parents and additional handicaps. The likelihood of a student wearing an aid is significantly related to certain educational settings, the degree of hearing loss, age and to a lesser extent, his method of communication.

Adolescent↗
PubMedDate not supplied

Synthesis and biological activity of LH-RH antagonists modified in position 1.

As part of our studies on the design of more potent antagonists of the LH-RH (luteinizing hormone-releasing hormone) decapeptide, twelve new highly soluble D-Arg6-analogs have been synthesized. These peptides contain modifications in position 1 and are typified by the general formula (N-acetyl-X1, D-p-Cl-Phe2, D-Trp3, D-Arg6, D-Ala10) LH-RH. We have found that a lyophilic, aromatic substituent is required in position 1 in order to elicit antiovulatory activity at a dose as low as 3 micrograms. The larger the hydrophobic amino acid (X: p-Br-Phe, beta-Nal-2) in position 1, the higher is the antiovulatory activity that can be attained. Analogs with non-aromatic or hydrophilic amino acids (X: Gly, Leu, Arg, His, Glu) in position 1 generally have much lower activities in this series of LH-RH antagonists.

Amino Acids↗
PubMedDate not supplied

Results of a randomised, multicentre study comparing a new water-based gel of clindamycin 1% versus clindamycin 1% topical solution in the treatment of acne vulgaris.

Several topical formulations of clindamycin phosphate are currently marketed for the treatment of acne vulgaris. This 12 week, multi-centre, investigator-blind, randomised, active and placebo-controlled, parallel group study assessed the clinical efficacy and safety of clindamycin 1% gel once-a-day vs clindamycin 1% solution twice-a-day, and to demonstrate its superiority vs its vehicle alone. A total of 592 subjects were included. After 12 weeks, a 65% reduction in inflammatory lesion count was observed with both active treatments. The gel was superior to its vehicle for total and inflammatory lesion reduction, Global Assessment of Improvement, and Global Severity Grade at final visit (all p < 0.01). No difference was found between the 2 active treatments for any of the evaluated criteria. Local tolerance in each active treatment group was slightly better with clindamycin gel (1.9% of subjects) relative to 3.1% in the topical solution group. In conclusion, the new water-based gel once-a-day formulation of clindamycin 1% is an effective, safe, and convenient alternative to the twice-a-day topical solution formulation in the treatment of acne vulgaris.

Acne Vulgaris↗