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Biomedical subjects

C Boyd

Publications and source records attributed to C Boyd.

At least 37 records · Page 2Linked to original sources
PubMed1990

Homograft valve durability: host or donor influence?

Antibiotic sterilized valves have been shown to function longer than those chemically sterilized; however, the reason remains obscure. Current hypotheses cite either retention of donor fibroblasts capable of repairing the grafted valve, or host fibroblast ingrowth into and onto the leaflet ground substance. A cryopreserved aortic homograft from a male donor was explanted from a female recipient after 10 months, and subjected to immunocytochemistry, tissue culture, and karyotyping. The leaflet bases exhibited normal morphology with an intact endothelium. The distal one-third of the leaflets was devoid of fibroblasts from the leaflet bases showed them to be of host origin. This homograft seems to have been implanted with an intact ground substance which allowed for host cell repopulation of the inner one-third of the leaflets. Perhaps donor cell viability in itself is not as important to durability as is preservation of the leaflet ground substance, but rather the presence of viable cells may be an index of the structural integrity of the collagen and elastic matrix.

Adult↗
PubMed1989

Luteal phase deficiency after completely normal follicular and periovulatory phases.

Luteal phase defect (LPD) accounts for a significant proportion of reproductive disorders, however its etiology is still debated. A prospective study was performed on 37 ovulatory women to determine whether LPD can occur in cycles characterized by completely normal folliculogenesis. Criteria for normal folliculogenesis included: a gradual rise of serum estradiol, a luteinizing hormone (LH) surge, the presence of a dominant follicle that disappeared, an increase of serum progesterone, and normal serum levels of prolactin, testosterone, dehydroepiandrosterone sulfate, follicle-stimulating hormone, and LH. Thirty of 37 women fulfilled the above mentioned strict criteria and underwent endometrial biopsy in the late luteal phase. Seven of 30 (23%) demonstrated a delay in endometrial development and all had normal hormonal and ultrasonographic parameters of folliculogenesis and ovulation. Women with delayed endometrial development demonstrated slightly longer follicular phases (17.0 +/- 1.1 versus 14.5 +/- 0.3 days). Perfectly normal follicular and periovulatory events may be followed by deficient luteal phases.

Adult↗
PubMed1987

Structure, polymorphism, and novel repeated DNA elements revealed by a complete sequence of the human alpha-fetoprotein gene.

The human alpha-fetoprotein gene spans 19,489 base pairs from the putative "Cap" site to the polyadenylation site. It is composed of 15 exons separated by 14 introns, which are symmetrically placed within the three domains of alpha-fetoprotein. In the 5' region, a putative TATAAA box is at position -21, and a variant sequence, CCAAC, of the common CAT box is at -65. Enhancer core sequences GTGGTTTAAAG are found in introns 3 and 4, and several copies of glucocorticoid response sequences AGATACAGTA are found on the template strand of the gene. There are six polymorphic sites within 4690 base pairs of contiguous DNA derived from two allelic alpha-fetoprotein genes. This amounts to a measured polymorphic frequency of 0.13%, or 6.4 X 10(-4)/site, which is about 5-10 times lower than values estimated from studies on polymorphic restriction sites in other regions of the human genome. There are four types of repetitive sequence elements in the introns and flanking regions of the human alpha-fetoprotein gene. At least one of these is apparently a novel structure (designated Xba) and is found as a pair of direct repeats, with one copy in intron 7 and the other in intron 8. It is conceivable that within the last 2 million years the copy in intron 8 gave rise to the repeat in intron 7. Their present location on both sides of exon 8 gives these sequences a potential for disrupting the functional integrity of the gene in the event of an unequal crossover between them. There are three Alu elements, one of which is in intron 4; the others are located in the 3' flanking region. A solitary Kpn repeat is found in intron 3. The Xba and Kpn repeats were only detected by complete sequencing of the introns. Neither X, Xba, nor Kpn elements are present in the related human albumin gene, whereas Alu's are present in different positions. From phylogenetic evidence, it appears that Alu elements were inserted into the alpha-fetoprotein gene at some time postdating the mammalian radiation 85 million years ago.

Base Sequence↗
PubMed1986

Reye's syndrome.

Explore the source record for details and available documents.

Female↗
PubMed1986

Ejection fraction by combined inverse Fourier analysis and second-derivative technique: correlation with isocontour method.

In order to measure ejection fractions (EFs) from nuclear ventriculograms, we devised a semi-automated edge-detection technique based on a combination of inverse Fourier analysis and second-derivative techniques. Initial clinical studies showed that, for the left ventricle, our method gives EF values statistically identical with those obtained using a conventional isocontour technique. For the right ventricle, however, the values obtained using the two methods were somewhat more at variance. Despite requiring a longer processing time, the results obtained with our method are reproducible because less operator intervention is necessary.

Fourier Analysis↗
PubMed1986

Mutations linked to the pro alpha 2(I) collagen gene are responsible for several cases of osteogenesis imperfecta type I.

We have analysed six South African families with osteogenesis imperfecta type I using three DNA polymorphisms associated with the pro alpha 2(I) collagen gene. In four of these families linkage of the pro alpha 2(I) gene and the osteogenesis imperfecta phenotype was suggested, whereas in the remaining two families there was a lack of linkage. No distinct correlation could be made between the phenotypic features of the families studied and linkage or lack of linkage to the pro alpha 2(I) gene. Two different haplotypes were found to be associated with the mutant pro alpha 2(I) alleles. These findings suggest that molecular heterogeneity exists within osteogenesis imperfecta type I and that in a significant proportion of cases the defect is linked to the pro alpha 2(I) gene.

DNA↗
PubMed1985

Structure of the 3' portion of the bovine elastin gene.

A bovine genomic library constructed by partial Sau3A digestion and contained in lambda Charon 30 was screened by in situ hybridization with a 1.3-kilobase (kb) sheep elastin cDNA clone [Yoon, K., May, M., Goldstein, N., Indik, Z., Oliver, L., Boyd, C., & Rosenbloom, J. (1984) Biochem. Biophys. Res. Commun. 118, 261-269]. Three clones encompassing 10 kb of the bovine elastin gene were identified and characterized by restriction mapping and DNA sequencing of the 6.2 kb of the most 3' region of the gene. These analyses have permitted localization of eight exons in the 6.2 kb in which the translated exons vary in size from 27 to 69 base pairs, and there is an approximately 1-kb untranslated region at the 3' end. In addition to identification of sequences homologous to those found in porcine tropoelastin, the analyses defined a 58 amino acid sequence that forms the carboxy-terminal region of tropoelastin, and this sequence, which contains two cysteine residues, was previously not observed in the protein sequence data. The analyses also suggest that functionally distinct cross-link and hydrophobic domains of the protein are encoded in separate exons.

Amino Acid Sequence↗
PubMed1985

Analysis of the 3' region of the sheep elastin gene.

The nucleotide sequences of a 1279-bp sheep elastin cDNA clone, pcSEL1 [Yoon et al. (1984) Biochem. Biophys. Res. Commun. 118, 261-269], and a 1230-bp sheep elastin genomic subclone, pSS1 [Davidson et al. (1984) Biochem. J. 220, 643-652], corresponding to a portion of the cDNA clone, were determined. These analyses permitted determination of the 100 amino acids at the carboxy terminus of sheep tropoelastin. A portion of this sequence showed strong homology to known sequences of pig tropoelastin, but most of the sequence had not been previously determined through protein sequencing. Novel aspects of the tropoelastin molecule which have been revealed by the present analyses are (i) the presence of an unusual sequence, KPPKP, which may contribute to crosslink formation; and (ii) the finding of cysteine within a sequence, CLGKSCGRKRK, at the putative carboxy terminus of tropoelastin. Because of the presence of these sequences, it is speculated that the carboxy-terminal region may be of importance in crosslinking tropoelastin molecules to themselves or to other matrix macromolecules. The nucleotide analyses revealed that sheep elastin mRNA contains a 974-bp untranslated sequence at the 3' end, which appears to be strongly conserved among species.

Animals↗
PubMed1985

Toward an understanding of mother-daughter identification using concept analysis.

Mother-daughter identification was analyzed using a concept analysis strategy proposed by Walker and Avant. This strategy was selected because of its utility in clarifying a concept requiring refinement. It was toward this goal that the concept analysis of mother-daughter identification was initiated. Rogers's conceptual model was used to add a new dimension to past conceptualizations of mother-daughter identification, one that allows the concept to be added to a nursing perspective.

Adult↗
PubMed1985

Chromosomal localization of the human elastin gene.

mRNA isolated from fetal human aorta was used to synthesize cDNA that was cloned into the PstI site of pBR322. The recombinant clones were screened with an authentic sheep elastin cDNA, and one human clone that hybridized strongly was isolated and characterized. The 421-base pair (bp) insert of this human clone was sequenced by the dideoxy method, and the DNA sequence showed strong homology to the nontranslated portion of the sheep elastin cDNA. This result unequivocally identified the human clone, designated pcHEL1, as an elastin clone. Plasmid pcHEL1 labeled with [3H] nucleotides was used in in situ hybridization experiments utilizing normal metaphase chromosomes and also with cells carrying a balanced translocation between chromosomes 1 and 2: 46,XY,t(1;2)(p36;q31). The results strongly suggest that the elastin gene is localized to the q31----qter region of chromosome 2.

Animals↗
PubMed1984

Elastin mRNA levels during foetal development of sheep nuchal ligament and lung. Hybridization to complementary and cloned DNA.

Elastin mRNA levels were quantified in sheep nuchal ligament and lung during the latter half of foetal development with elastin-specific cDNA (complementary DNA) probes using both hybridization in solution (saturation analysis) and hybridization on a fixed support (Northern analysis). For the solution-hybridization studies, cDNA prepared from nuchal-ligament mRNA was enriched to 65% for elastin sequences by hybridizing it to its template at a R0t (mol X s X litre-1) value that included only the abundant class of mRNA sequences. Hybridization of this probe to RNA extracted from nuchal ligament between 70 and 138 days after conception demonstrated elastin sequences increased about 10-fold (from 0.047 to 0.438% of total RNA). In contrast, lung elastin mRNA levels increased only 3-fold (from 0.009 to 0.022% of total RNA) during the same period. Over this development period these values correspond to increases in the average number of elastin mRNA molecules from 950 to 20 000 molecules/ligament cell and from 130 to 330 molecules/lung cell. For Northern analysis, elastin mRNA was purified from near-term-sheep nuchal ligament on sucrose density gradients. Analysis of the translation products of this elastin mRNA showed that relative elastin precursor synthesis was at least 80% of total [3H]valine incorporation. The Mr of this elastin mRNA, determined by methylmercury-agarose-gel electrophoresis, was approx. 1.25 X 10(6). Northern hybridization of nuchal ligament and lung RNA to a [32P]cDNA probe, transcribed from this sucrose-gradient-purified elastin mRNA, confirmed the developmental changes in elastin mRNA levels detected by solution-hybridization techniques. The specificity of this method was confirmed by using a cloned elastin gene fragment. These studies demonstrate that elastin mRNA levels in organs such as nuchal ligament and lung increase with foetal development, but that there are significant differences in the average cellular elastin mRNA content of these two organs.

Animals↗
PubMed1984

Characterization of a sheep elastin cDNA clone containing translated sequences.

mRNA, isolated from the ligamentum nuchae of fetal sheep by guanidine HCl extraction and oligo(dT) cellulose chromatography, was used to synthesize blunt-ended cDNA molecules by the successive application of AMV reverse transcriptase, DNA polymerase and S1 nuclease. The cDNA was centrifuged on a 15-30% sucrose gradient and molecules greater than 700 bp were tailed with dCTP and cloned into the PstI site of pBR322 which had been tailed with dGTP. Ampicillin-sensitive and tetracycline-resistant colonies were screened by in situ hybridization with elastin-enriched mRNA that had been terminally labeled with 32p. Recombinant plasmids prepared from strongly hybridizing colonies were characterized by restriction mapping and the plasmid with the largest insert (1300 bp) thought to contain elastin sequences was characterized in more detail. The nick-translated cDNA hybridized to a single 3.5 kb mRNA species upon blot hybridization, a size identical to that previously identified for chick elastin mRNA (Burnett et al. (1982) J. Biol. Chem. 259, 1569-1572). Nucleotide sequencing of the 5' end of the cDNA demonstrated a sequence which was extremely GC rich and which corresponded to an amino acid sequence partially homologous to that previously identified in porcine tropoelastin (Foster et al. (1973) J. Biol. Chem. 248, 2876-2879). This is the first report of the identification of a plasmid containing sequences complementary to a translated region of elastin mRNA.

Amino Acid Sequence↗
PubMed1984

Blot hybridisation analysis of genomic DNA.

Restriction endonuclease analysis of specific gene sequences is proving to be a valuable technique for characterisation and diagnosis of inherited disorders. This paper describes detailed protocols for isolation, restriction, and blot hybridisation of genomic DNA. Problems and alternatives in the procedure are discussed and a troubleshooting guide has been provided to help rectify faults.

Autoradiography↗
PubMed1983

Addicted women and their relationships with men.

The information for this descriptive study comes from Andersen's (1980) research funded through the National Institute on Drug Abuse. Although Andersen's questionnaires do not directly gather data about the relationship between the woman's drug use and her relationships with men, the authors were drawn to explore this area because of the large number of female drug users who described this connection. In reviewing the initial and termination data on 72 clients, it was found that 43% reported a variety of ways their usage was affected by men. These anecdotal descriptions provided by the female drug users are summarized under seven headings; some anecdotal notes are included in the text. The categories are not mutually exclusive. The findings reported in this article concur with the recent literature on drug dependent women.

Adult↗
PubMed1982

Studies of DNA damage and cell death in embryonic limb buds induced by teratogenic exposure to cyclophosphamide.

Many teratologic investigations have shown that certain types of chemical insults to the embryo (those altering replication, transcription, and translation) can cause excessive cell death in tissues destined to become malformed. Chemical carcinogens also induce cell death in target tissues, but the critical event is believed to be heritable alteration in the DNA of surviving cells. In the present study, an attempt was made to study the interaction between cell death and DNA damage in the initiation of birth defects. The pattern of DNA damage induced by cyclophosphamide was examined at time intervals before, during, and after the necrotic episode in mouse embryo limb buds. The alkaline elution assay was used to measure alkali-labile sites in single-strand DNA due to its adaptability to small tissue samples. An ip dose of 20 mg/kg of cyclophosphamide induced forelimb malformations in 85% of surviving mouse fetuses and 30% embryolethality when administered at 9 am on Day 11. As early as 5 hr after exposure, a slight excess of necrosis was observed in treated limbs by light microscopy, while at 24 hr, massive necrosis was evident. By 48 and 72 hr, excess necrosis was not observed in treated limbs. When alkaline elution analysis was conducted at prenecrotic (1-, and 5-hr), necrotic (24-hr), and postnecrotic (48-, and 72-hr) intervals, a trend toward increasing DNA damage in treated limbs with time was observed. The greatest differences in elution values occurred during the postnecrotic period. Although mean retention values were not significantly different, significantly increased variance was obtained in retention values of treated limbs at all time intervals other than 1 hr. This may reflect the actual in vivo situation where relatively few cells within a heterogeneous population of cells carry sublethal DNA damage into the postnecrotic period. These results suggest that not all limb bud cells affected by teratogenic exposure to cyclophosphamide die, but that some persist to the postnecrotic period carrying heritable alterations in their DNA.

Abnormalities, Drug-Induced↗