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At least 73 records · Page 4Linked to original sources
PubMed1957

Detection of gynecological cancer; use of fluorescence microscopy to show nucleic acids in malignant growth.

Early detection of malignant lesions of the cervix, a major problem in gynecology, has been made possible in more cases by the development of exfoliative cytology. Mass-screening programs have been impeded, however, by the demands on time and skill of the examiner as posed by conventional techniques.A new method in exfoliative cytology, using fluorescence microscopy, essentially reduces the time of processing as well as of scanning of specimens. Suspicious cells show flaming orange-red fluorescence of the cytoplasm on a black background, impressively distinct from normal cells and giving a warning signal to the examiner. This color reaction is based upon cytochemical changes-namely, the abundance of ribonucleic acid in vividly growing and especially malignant cells.Besides gynecological material, the method is applicable to other forms of malignant disease.

Cytodiagnosis↗
PubMed1959

The metabolism of chromosomal ribonucleic acid in Drosophila salivary glands and its relation to synthesis of desoxyribonucleic acid.

Incorporation of adenine-8-C(14) into chromosomal nucleic acids of Drosophila salivary glands has been observed with the autoradiographic technique. RNA-C(14) and DNA-C(14) were detected as the fractions extractable by ribonuclease digestion and resistant to ribonuclease, respectively. Extractions with desoxyribonuclease and acids were also used to identify the nucleic acids. Time-course curves were determined from grain counts. RNA-C(14) concentration reached a maximum in 2 hours, and decreased after the 4th hour. DNA-C(14) concentration reached its maximum within 8 hours, and showed no decreases during a 48-hour experiment. In the latter part of the period of observation, morphological differentiation of the gland occurred, the decrease in RNA-C(14) became very rapid, and a large increase in DNA-C(14) was observed. Marked decrease in RNA-C(14) and increase in DNA-C(14) were detectable in a few hours when isotope was administered shortly before visible differentiation of the gland. Measurements of nuclear size indicated no significant decreases in RNA-C(14) amount prior to the period of differentiation. During this later period, a large decrease in RNA-C(14) amount occurs suddenly, and the same amount of C(14) is added simultaneously to the DNA fraction, as expected if RNA-C(14) is utilized in the synthesis of DNA.

Animals↗
PubMed1961

Quantitative radioautographic studies on exponentially growing cultures of Escherichia coli. The distribution of parental DNA, RNA, protein, and cell wall among progeny cells.

Exponentially growing cultures of E. coli were examined by quantitative radioautographic techniques to determine the distribution of labeled DNA, RNA, protein, and cell wall among the progeny cells of successive generations. It was found that DNA is in large structures, non-randomly distributed in the progeny. About one-half of the cells have four such structures and approximately one-half contain these four structures plus four smaller ones. These structures show remarkable stability. Fewer than 3.5 per cent of the large structures break in one division time. Protein, RNA, and cell wall are all distributed randomly among progeny cells. The number of units of each component that show random segregation must be 200 or more.

Autoradiography↗