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Biomedical subjects

M Fry

Publications and source records attributed to M Fry.

124 records · Page 7Linked to original sources
PubMed1972

A new synthetic RNA-dependent DNA polymerase from human tissue culture cells (HeLa-fibroblast-synthetic oligonucleotides-template-purified enzymes).

Two DNA polymerases that can copy synthetic RNA polymers are present in human tissue culture cells. These enzymes which have each been purified about 500-fold, are present in both HeLa cells, which are derived from a cervical carcinoma, and in WI-38 cells, a normal diploid strain originating from human embryonic lung tissue. These synthetic RNA-dependent DNA polymerases are identified by their ability to copy efficiently the ribo strand of synthetic oligonucleotide-homopolymer complexes, and differ in this respect from the known DNA-dependent DNA polymerases found in HeLa cells. The template requirements of these new DNA polymerases resemble that of the RNA-dependent DNA polymerases of the RNA tumor-viruses.

Cell Line↗
PubMed1969

Deoxyribonucleic acid-ribonucleic acid hybridization. Annealing and quantitative recovery of intact ribosomal ribonucleic acid molecules from hybrids.

A simple and efficient method for hybridization and subsequent recovery of non-fragmented ribosomal RNA from the hybrid is described. The procedure involves annealing of immobilized denatured DNA bound on cellulose nitrate membrane filters to complementary RNA in 50% (v/v) formamide-0.33m-potassium chloride-10mm-tris-hydrochloric acid buffer, pH7.4, at 33 degrees for 3hr. Under these conditions no detectable changes in the sedimentation coefficients of the input RNA were detected. The RNA can subsequently be recovered quantitatively from the hybrid in intact form by incubating the filters in formamide or in 85% (v/v) dimethyl sulphoxide. The applicability of the method for the evaluation of the absolute size of ribosomal RNA cistrons in Escherichia coli DNA and for the determination of the size of messenger RNA molecules is discussed.

Buffers↗
PubMed1969

Studies of newly synthesized ribosomal ribonucleic acid of Escherichia coli.

1. RNA synthesized by Escherichia coli during one-hundredth of the generation time contains two fractions distinguishable by hybridization with homologous DNA. One fraction, approximately 30% of the newly synthesized RNA, did not compete with ribosomal RNA, being apparently messenger RNA. The other fraction, approximately 70% of the newly made RNA, hybridized as ribosomal RNA. These values are comparable with previous estimates (McCarthy & Bolton, 1964; Pigott & Midgley, 1968). 2. Hybridization-competition experiments showed that the newly made RNA associated with 70s ribosomes and larger ribosome aggregates was a mixture of ribosomal RNA and messenger RNA, whereas that associated with nascent ribosomal subunits consisted exclusively of ribosomal RNA. This observation provides means by which newly synthesized ribosomal RNA can be isolated free from messenger RNA. 3. Newly made ribosomal RNA in nascent ribosomal subunits was sensitive to shear under conditions where ribosomal RNA in mature ribosomes was shear-resistant. Thus, when RNA was extracted from cells of E. coli disrupted by mechanical means, newly made ribosomal RNA appeared heterogeneous in size, sedimenting as a broad peak extending from 8s to 16s. 4. Newly synthesized ribosomal RNA in nascent ribosomal subunits was rapidly degraded in the presence of actinomycin D and during glucose starvation. 5. Newly synthesized ribosomal RNA stimulated amino acid incorporation in a system synthesizing protein in vitro to the same extent as the RNA which contained the messenger RNA fraction.

Amino Acids↗
PubMedDate not supplied

Chick embryo fibroblasts senscence in vitro: pattern of cell division and life span as a function of cell density.

The pattern of cell division, ageing and death of cultured chick embryo fibroblasts inoculated at a wide range of cell densities is described. Cell populations seeded at densities of 2.1 x 10-3 to 3.1 x 10-4 cells per cm-2 double between 39 and 17 times respectively while their life span at all densities remains 57 puls or minus 3 days. Thus, under the experimental conditions employed, the life span of cultured embryonic chick cells is a function of calendar rather than mitotic time. We also find that the duration of phase III and the generation time of the cells during this period are proportional to the density of the culture. Moreover, the division rate of cells inoculated at low densities (4.2-31.0 x 10-2 cells per cm-2) remains constant throughout their entire lifetime. It is suggested that the decline in the proliferative capacity of chick cells ageing in vitro is a function of both their density and their age.

Aging↗
PubMedDate not supplied

Product evaluation and standardization.

Although it was cumbersome at the time of implementation, the process began to operate effectively once hospital personnel overcame their initial concern over a potential "paperwork jungle" and realized that the paperwork is easy to control. When implementing such a system, it is vital that all personnel make a commitment to the process. Although it can be time-consuming and demanding in that employees must attend meetings, write standards, conduct and coordinate evaluations, the benefits are paid back many times over, both in dollars and staff satisfaction. A major plus of our system is our requirement that the user justify why a product is needed. That need is explained in the content of a product standard. The demerit rating system, while not a precise mathematical science, does indicate the relative importance of each criterion. The final result is a standard product, a standard process and a standard decision, against which both product and process performance can be measured. This measurement is a level of professionalism achieved by the actions of a motivated staff, working in cooperation toward a single goal.

British Columbia↗
PubMedDate not supplied

Management monopoly.

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Administrative Personnel↗