Search PubMed⌕ Search

Biomedical subjects

S A Latt

Publications and source records attributed to S A Latt.

At least 145 records · Page 8Linked to original sources
PubMed1974

Sister chromatid exchanges, indices of human chromosome damage and repair: detection by fluorescence and induction by mitomycin C.

Sister chromatid exchanges in chromosomes from human lymphocytes grown two replication cycles in medium containing 5-bromodeoxyuridine can be detected by fluorescence microscopy after staining with the bisbenzimidazole dye 33258 Hoechst. These exchanges are much more frequent than chromosome or chromatid breaks and appear to be partly but not entirely due to 5-bromodeoxyuridine incorporation. Sister chromatid exchanges are extremely sensitive indicators of chromosome damage produced by DNA cross-linking agents such as mitomycin C. Significant increases in the sister chromatid exchange frequency occur with 3 ng/ml of mitomycin C; higher concentrations of mitomycin C induce further sister chromatid exchanges. Comparatively few gross chromosomal aberrations are seen in cells exhibiting as many as one hundred or more sister chromatid exchanges. Most of the damage caused by mitomycin C to chromosomal DNA is apparently repaired without detectable changes in chromosome morphology. Analysis of sister chromatid exchanges may permit more sensitive detection of damage to DNA caused by other agents than has previously been possible by classical cytological techniques.

Benzimidazoles↗
PubMed1973

Microfluorometric detection of deoxyribonucleic acid replication in human metaphase chromosomes.

Fluorescence of the dye 33258 Hoechst bound to chromosomes is partially quenched by the introduction of BrdU into chromosomal DNA. This finding has allowed microfluorometric detection of DNA synthesis in human metaphase chromosomes. Incorporation, shortly before cell harvest, of a pulse of thymidine into chromosomes otherwise substituted with BrdU results in sharply defined foci of bright 33258 Hoechst fluorescence, corresponding to regions of late DNA replication. The latereplicating X chromosome can thereby be clearly identified, and the time course of appearance of its fluorescent bands can be compared with that of its earlier replicating homologue. Growth of cells in medium containing BrdU for two generations allows fluorometric documentation of the semiconservative distribution of newly replicated DNA between sister chromatids, and regions of sister chromated exchange are demarcated. This approach should constitute, in many instances, a convenient, high-resolution fluorometric alternative to autoradiography.

Autoradiography↗
PubMed1970

Surveyor substrates: energy-transfer gauges of active center topography during catalysis.

An approach is described for the simultaneous measurement of catalysis, the distance from an active-site moiety to fluorescent substrate moieties of an enzyme substrate complex, and the microenvironment of such substrate groups. It is illustrated by means of a three-component energy transfer relay system, consisting of cobalt carboxypeptidase, its fluorescent dansylated peptide substrates, and tryptophanyl residues of the enzyme. The mode of procedure can be applied generally to yield conjoint information on functional and structural aspects of active centers of enzymes.

Binding Sites↗