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Biomedical subjects

W F Anderson

Publications and source records attributed to W F Anderson.

At least 325 records · Page 18Linked to original sources
PubMed1977

The problem of nuclease activity in nucleic acid hybridization reactions. Theoretical considerations.

The presence of nuclease during DNA-DNA or DNA-RNA hybridization reactions alters the kinetics of hybrid formation. Unfortunately, while the effect (even of small amounts of nucleas) on the Cot curve may be large, it may not be readily detectable. The effect of various types of nuclease is shown. As many nucleases cause a shift in the position rather than a change in shape of the curve, all studies involving nucleic acid hybridization should assay for the presence of nucleases and care must be taken to avoid their presence as contaminants.

DNA↗
PubMed1977

Extinction of hemoglobin inducibility in Friend erythroleukemia cells by fusion with cytoplasm of enucleated mouse neuroblastoma or fibroblast cells.

Friend mouse erythroleukemia cells (T3c1-2 and its subline 5000) can be induced to synthesize hemoglobin after treatment with 1.5% (vol/vol) dimethylsulfoxide. When these cells are fused with nonerythroid cells (namely, mouse neuroblastoma or L cells) hemoglobin induction is extinguished. In order to determine if the nucleus of the nonerythroid cell is necessary for this extinction, fusions were performed between mouse erythroleukemia cells and enucleated neuroblastoma or L cells. Hemoglobin induction was reduced or eliminated in clones of these hybrids even after 6 months of continuous culture. These results suggest that the cytoplasm of nonerythroid cells contains factor(s) that extinguish hemoglobin inducibility in erythroleukemic cells and that this new phenotype can be inherited.

Animals↗
PubMed1976

The clinical assessment of ageing and problems of diagnosis in the elderly.

The elderly patient presents special problems to the clinician. Accurate diagnosis in the elderly requires an understanding of the interrelationship between mental and physical illness, the altered physiology of the aged and the realisation that multiple pathology is the rule rather than the exception. The onset of illness is frequently insidious and the presentation often atypical.

Aged↗
PubMed1976

Geriatric medicine - the challenge of the 1970s.

The rising number of elderly people in the community poses a great challenge to the medical and allied professions. This article outlines the urgent need for the planning and provision of comprehensive services for the elderly. The importance of health surveillance, a preventive approach and the health team work is stressed. The need for the introduction of geriatrics into undergraduate and postgraduate medical education is emphasised.

Aged↗
PubMed1976

Importance of full size complementary DNA in nucleic acid hybridization.

The size of the DNA product synthesized by RNA-directed DNA polymerase (isolated from avian myeloblastosis virus) was found to be important for complementary DNA (cDNA)-mRNA hybridization reactions. Incomplete cDNA to rabbit reticulocyte globin mRNA formed poor hybrids and presumably lacked sequences needed for hybridization. The size of the cDNA synthesized was influenced by the reaction conditions used. The complementary DNA product contained 10 S material when synthesis was done at high deoxynucleoside triphosphate concentrations (greater than 50 muM) while the product was smaller than the template when synthesis was at lower concentrations. The concentration and size (oligo(dT)6 to (dT)10) of primer had little or no effect on the product size. Increasing the concentration of 10 S globin mRNA caused the cDNA product to contain more small material. The cDNA synthesized at high deoxynucleoside triphosphate concentrations was fractionated into heavy, medium, and light fractions by alkaline sucrose density centrifugation. All hybridized to globin mRNA. The larger cDNAs had a higher TM when hybridized to globin mRNA, a lower dTMP/dCMP ratio (indicating that the poly(dT) region constituted a smaller fraction of the molecule), and gave increased protection of 125I-labeled mRNA from nuclease digestion. The full size cDNA was especially useful for studying the RNA transcribed from chromatin by RNA polymerase. The complement of the 5' end of the mRNA is contained only in full size cDNA; the 5' end is the part of the mRNA first transcribed by the RNA polymerase assuming correct transcription. Thus, full size cDNA can hybridize more effectively to the short RNA transcripts that are obtained than partial cDNA. RNA transcribed from rabbit bone marrow chromatin by Escherichia coli RNA polymerase hybridized twice as efficiently to complete cDNA as it did to partial cDNA demonstrating the usefulness of full size cDNA.

Animals↗
PubMed1976

Extinction of globin gene expression in human fibroblast x mouse erythroleukemia cell hybrids.

We have chosen human fibroblast x mouse erythroleukemia hybrid cells as a model system to examine regulation of unique genes. The globin genes were studied as a marker of erythroid differentiation. Three separate hybrid cell lines were incubated in 2% dimethylsulfoxide, an agent which induces erythroid differentiation of the parental erythroleukemia cells. Neither human nor mouse globin mRNA sequences could be detected by a sensitive molecular hybridization assay which utilized globin complementary D N A. However, td n a from one of the cell lines was shown to contain both the mouse and humand globin genes. Thus, loss of the genes by chromosomal segregation did not account for their failure to be expressed. Cocultivation of the mouse erythroleukemia cells with excess human fibroblasts did not prevent erythroid differentiation of the erythroleukemia cells in the presence of dimethylsulfoxide. Similarly globin gene expression was preserved in tetraploid cells generated by fusion of two erythroleukemia lines. Thus, extinction of globin geneated by fusion of two erythroleukemia lines. Thus, extinction of blobin gene expression in the human fibroblast x erythroleukemia hybrids occurred at the level of mRNA production and appeared to be due to the presence of the fibroblast genome within the hybrial cell.

Animals↗
PubMed1976

Polypeptide chain initiation in eukaryotes: initiation factor requirements for translation of natural messengers.

A protein-synthesizing system consisting of ribosomes and supernatant of undeveloped Artemia saline embryos is used for assay of mRNA translation and initiation factors. This system contains the components needed for chain elongation but has low levels of mRNA and initiation factors. Exogenous mRNA is readily translated upon addition of high-speed supernatant or ribosomal salt wash of developing embryos as a source of initiation factors (IF). This requirement can be largely satisfied by a mixture of the reticulocyte factors IF-MP, IF-M3, IF-M2A, and IF-M2B. A. salina IF-M1, which is present in undeveloped embryo supernatant, can be inactivated by A. salina IF-M1 antibody without affecting translation.

Animals↗
PubMed1976

Polypeptide chain initiation in eukaryotes: mechanism of formation of initiation complex.

Artemia salina ribosomal subunits and highly purified reticulocyte initiation factors (IF) are used to study the mechanism of formation of the puromycin-sensitive initiation complex Met-tRNAi-80S ribosome-AUG. A complex with equimolar amounts of 40S subunit, GTP, and Met-tRNAi is formed at low Mg2+ concentration with a requirement for IF-MP (homogeneous) but not AUG or other factors. An 80S complex is formed only upon the further addition of AUG, IF-M2A, and IF-M2B, but not of either factor alone. This complex contains no GTP or GDP. A 40S complex, which cannot be converted to an 80S one, is formed when the nonhydrolyzable analog GMPPCP is substituted for GTP. IF-M2A has no effect on the formation of this complex, but IF-M2B enhances its formation.

Animals↗
PubMed1976

Transcription of single base oligonucleotides by ribonucleic acid-directed deoxyribonucleic acid polymerase.

The synthesis of DNA products complementary to artificial templates by the enzyme RNA-directed DNA polymerase isolated from avian myeloblastosis virus has been studied. Of the single base polyribonucleotides, poly (rC), poly(rA), and poly(rI) were active while poly (rG) and poly (rU) were almost inactive. The minimum length showing activity for an oligo (rC) template was 9; the minimum primer length of oligo(dG) was 3 or 4. In order to examine the fidelity of transcription, single base oligoribonucleotides of defined length were studied. Using (rC)13 as template and (dG)8as primer, the oligo (dG) product coelectrophoresed with the template. However, using (rA)-20 as template and (dT)10 as primer, a large (10-16s) product was formed. Similarly, using oligo (rI) (2.5S) as template and (dC)10 as primer, a large (greater than 22s) product was formed. No significant activity was obtained with oligo (rU) templates. RNA-directed DNA polymerase transcribes the various oligonucleotides differently: slippage with oligo (rA) and oligo (rI), faithful transcription with oligo (rC), and poor transcription with oligo (rU).

Avian Myeloblastosis Virus↗
PubMed1976

Hemoglobin McKees Rocks (alpha2beta2145Tyr leads to Term). A human "nonsense" mutation leading to a shortened beta-chain.

The first example of the premature termination of a polypeptide chain in man appears to be Hb McKees Rocks, beta145 Tyr leads to Term, discovered in polycythemic members of a Caucasian family. Point mutation has apparently occurred at the codon for Tyr beta145 from UAU to a "nonsense" codon, UAA or UAG, resulting in a shortened polypeptide chain with Lys 144 as its carboxyl-terminal amino acid. Evidence for this structural conclusion is the absence of tryptic peptide betaT-15 from "fingerprints" of the abnormal beta-chain, the finding of C-terminal Lys, and the similarity between the functional properties of this variant hemoglobin and those of des Tyr (145)-His(146)beta hemoglobin resulting from carboxypeptidase-A digestion of normal human hemoglobin. Hb McKees Rocks has markedly abnormal properties: its oxygen affinity is the highest of the human variants described to date; its Bohr effect is reduced; it is devoid of subunit cooperativity; and it is unaffected by 2,3-diphosphoglyceric acid. These properties are probably the consequences of decreased stability of the T quaternary conformation and are partially restored in the presence of the strong allosteric effector inositol hexaphosphate.

Adult↗