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Biomedical subjects

M Chastain

Publications and source records attributed to M Chastain.

6 recordsLinked to original sources
PubMed1992

A base-triple structural domain in RNA.

An oligonucleotide modeled on a proposed base-triple domain of the Tetrahymena group I intron has been characterized by NMR. The oligonucleotide contains two double-helix regions with adjacent single-stranded nucleotides. The NMR data show that the two helices stack coaxially, although the rotation between the two helices is approximately twice as large as the rotation between normal base pairs. The rotation between the two helices allows the single-stranded nucleotides to form U.U.G and A.G.C base triples in the minor groove. The A.G.C base triple contains a hydrogen bond between the adenine N1 and a 2'-hydroxyl in the minor groove of the G.C pair. A similar hydrogen bond between an adenine and a 2'-hydroxyl in transfer RNA suggests that this could be a recurring tertiary interaction in RNA.

Animals↗
PubMed1992

Poly(rA) binds poly(rG).poly(rC) to form a triple helix.

Poly(rA) binds poly(rG).poly(rC) to form a triple helix. Evidence for this structure includes ultraviolet absorbance mixing curves and melting curves, and circular dichroism spectroscopy. The formation of the triple helix depends on the length of the poly(rC) strand. Triple helix forms when the average length is around 100 nucleotides but does not form when the average length is about 500 nucleotides.

Circular Dichroism↗
PubMed1991

Synthesis and purification of large amounts of RNA oligonucleotides.

Biophysical studies of RNA oligonucleotides require milligram amounts of RNA of specific length and sequence. Transcription from synthetic DNA templates using T7 RNA polymerase is a convenient method for synthesis of RNA oligonucleotides ranging in size from 9 to about 45 nucleotides. Here we present methods that make the large-scale synthesis of RNA oligonucleotides practical. This paper describes a rapid method for isolating T7 RNA polymerase free from RNases for use in transcription reactions. Protocols are also described for purification of the desired RNA oligonucleotide from the other products of transcription.

Base Sequence↗
PubMed1990

Cryogenically preserved adult and juvenile goat mandibular condylar transplantation.

Loss of a functional temporomandibular joint (TMJ) has long been a clinical challenge in both children and adults. Although reconstruction to date has been performed with various prosthetic devices or autogenous costochondral grafts, these procedures have a potential for complications and morbidity. Our studies were performed to determine the feasibility of healing, growth, and long-term function of TMJ reconstruction techniques with cryogenically preserved mandibular allografts in the goat model. This species was chosen because the surgical anatomy and biomechanics of the goat TMJ are very similar to those of the human TMJ. The positive results of the studies and their relevance will be described.

Animals↗
PubMed1988

Transplantation of cryogenically preserved mandibular condyles in the adult and juvenile goat.

Loss of a functional temporomandibular joint (TMJ), due to various causes including tumor resection, joint disease such as osteonecrosis, and injury or trauma, has long been a clinical challenge in both children and adults. It may be a significant problem facing physicians during another war. While reconstruction to date has been performed with various prosthetic devices or autogenous costochondral grafts, these procedures have a potential for complications and morbidity. This procedure could adversely delay the return of military members to a combat unit, or affect their ability to serve as functional members of society. Our studies were performed to determine the feasibility of TMJ reconstruction techniques, healing, and long-term function and growth using cryogenically preserved mandibular allografts in the goat. This species was chosen because the surgical anatomy and biomechanics of the goat TMJ are very similar to that of the human. The positive results of the studies and their relevance to future military medical readiness and civilian medicine will be described.

Age Factors↗