Biomedical subjects
Publications and source records attributed to D S Weinstein.
A case of sarcoidosis demonstrating an unusual pattern of profuse micronodular calcification is presented. The striking similarity with the so-called pathognomonic appearance of pulmonary alveolar microlithiasis and the progressive deterioration of pulmonary function are emphasized.
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BACKGROUND: Triple-helical nucleic acids, first reported in the late 1950s, are receiving attention for their possible involvement in controlling gene expression. Certain sequences of DNA are believed to form local triple-helical structures (H-form DNA), although this has not been directly observed in vivo. Studies carried out in our laboratories have suggested that self-replicating oligonucleotides could have been involved in chemical evolution via triple-helical intermediates. In addition to self-replication mechanisms, elucidating processes for the nonenzymatic elongation of biologically relevant polymers remains an important challenge in understanding the origin of life. To this end, we have studied a novel ligation of oligodeoxyribonucleotides that lie within a triple helix. RESULTS: The chemical end-ligation of homopyrimidine oligodeoxyribonucleotides on a triple helix is reported. This selective process, induced by cyanoimidazole, is facilitated by a template effect of the DNA aggregate and occurs between the 3' end (hydroxyl) of the third minor-groove-bound strand and the 5' end (phosphate) of the antiparallel oligopyrimidine strand. CONCLUSIONS: Double-helical homopurine/homopyrimidine DNA can serve as a template for the elongation of oligonucleotides in a manner that has not been described previously. The end-ligation of homopyrimidine oligomers, a nonenzymatic process, proceeds via a requisite triple-helical intermediate and constitutes an efficient and selective method for the template-directed elongation of nucleic acids. Such a process could conceivably have been involved in the elongation of primordial information-bearing biopolymers.
This article is intended to assist the nurse in caring for the patient who requires medical nutritional formulas, either as a complete diet or as a dietary supplement, to increase the nurse's knowledge of formula components, when and why different formulas are used, and when a change in formula may be indicated. Common formulas are broadly categorized throughout the article based on the form of the protein.
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Explore the source record for details and available documents.