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Biomedical subjects

S L Liem

Publications and source records attributed to S L Liem.

23 records · Page 2Linked to original sources
PubMed1981

The relationship between aging and ribosomal gene activity in humans as evidenced by silver staining.

Silver selectively stains nucleolar organizer regions (NORs) distributed on the D and G chromosomes of man. The number of NORs is fairly constant for a given individual but is highly variable within populations. When 2540 metaphases from lymphocytes were examined from 127 normal subjects, a mean NOR number of 7.3 was obtained with a mode of 7. No significant difference was found in mean NOR number between females and males. However, regression lines do show a decrease in NOR number with aging for both sexes but the rate of decline is more evident in females. Also, G chromosome NORs appear more stable than those in D chromosomes. Since silver--NOR staining is indicative of ribosomal gene activity, it is proposed that lymphocyte rDNA becomes less sensitive to phytohemagglutinin stimulation during aging. It is unique that this gene repression can be visualized with conventional staining and light microscopy.

Adolescent↗
PubMed1981

Variation in nucleolar organizer activity in lymphocytes of females with adenocarcinoma.

With the use of Ag staining and conventional light microscopy, a difference is visualized in the frequency of nucleolar organizer regions between PHA-stimulated lymphocytes from normal females and females with various types of adenocarcinoma. This difference in NOR activity is more pronounced in G chromosome than D chromosomes. It is feasible that rDNA gene activity in PHA-stimulated lymphocytes is augmented in patients with adenocarcinoma due to the presence of plasma mediators arising from cellular malignancies. The NOR regions located on G chromosomes are considered to be more sensitive to these mediators than those on D chromosomes.

Adenocarcinoma↗
PubMed1977

Distribution patterns of satellite associations in human lymphocytes relative to age and sex.

Using ammoniacal silver for differential staining of satellites, associations from 1,668 human metaphases were studied from lymphocyte cultures of 167 normal individuals and were correlated with age and sex. There is a peak in satellite association frequency up to age 20 years in males and to 25 in females. With older ages there is a decline in association frequencies. No associations with four or more chromosomes were found in newborns. Furthermore, association in newborns, as well as in individuals older than 50 years, are significantly low compared to in-between age groups. Females have a higher frequency of satellite associations than males between the ages of 3 and 50 years. Typically, females have greater multiple associations, while males have more single associations. Randomness or non-randomness of occurrence of associations fluctuates for different age groups within and between the two sexes.

Adolescent↗