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Biomedical subjects

A C Wilson

Publications and source records attributed to A C Wilson.

At least 127 records · Page 7Linked to original sources
PubMed1989

Multiple cDNA sequences and the evolution of bovine stomach lysozyme.

To investigate the origin of stomach expression of lysozyme in ruminants; we surveyed clones from a cow stomach cDNA library with a lysozyme cDNA probe. Ten percent of the clones in this library were lysozyme-specific. Thirty of the lysozyme clones were sequenced, and seven types of lysozyme mRNA sequence were found. They encode the three previously identified stomach isozymes of lysozyme. The seven sequences are closely related to one another and represent the products of a minimum of 4 of the approximately 10 cow lysozyme genes detected by genomic blotting. The most abundant form of stomach lysozyme (form 2) is encoded by at least two genes, whereas forms 1 and 3 are possibly each encoded by only one gene. The number of genes encoding each isozyme appears to contribute the largest factor in the relative abundance of each isozyme. The multiple lysozyme genes expressed in the cow stomach are the result of gene duplications that occurred during ruminant evolution. The recruitment of lysozyme as a major enzyme in the stomach may thus have involved an early regulatory event and a later 4-7-fold increase in expression allowed by gene amplification. During this period, the amino acid sequences of these lysozymes have been evolving more slowly than those of nonruminant lysozymes.

Abomasum↗
PubMed1989

Early and late survival after coronary-artery surgery.

Between 1970 and 1985, 1801 patients underwent coronary-artery surgery without associated valvular surgery. Eighty-four per cent of patients were male and the mean (+/- SD) age was 55.7 +/- 8.3 years. Of the patients, 18.7% were from the Coronary Care Unit and 6.5% had diabetes. The hospital mortality rate for the whole group was 3.5%. Patients from the Coronary Care Unit had the highest (8.9%) hospital mortality rate compared with those patients who were not from the Coronary Care Unit (2.1%; P less than 0.001). Other factors which increased the hospital mortality rate significantly were the number of diseased vessels (P less than 0.01), the degree of left main coronary-artery stenosis (P less than 0.001), an earlier year of surgery (P less than 0.01) and female sex (P less than 0.01). After these were taken into account, no other factors (for example, age, preoperative infarction, presence of left-ventricular aneurysm, left-ventricular end-diastolic pressure, diabetes, use of mammary-arterial grafts or the need for endarterectomy) affected the mortality rate. Patients were followed-up for a mean (+/- SD) of 4.4 +/- 2.8 years. The five-year survival rate for all patients was 88% and the 10-year survival rate was 65%. Cox regression analysis showed that the significant indicators of decreased long-term survival were undergoing operation directly from the Coronary Care Unit (P less than 0.001), left main coronary-artery stenosis (P less than 0.01), the number of grafted vessels (P less than 0.01), concomitant surgery for aneurysm (P less than 0.001), year of surgery (P less than 0.01). Seventy-nine per cent of patients were free of angina pectoris at five years after operation. The year of surgery (P less than 0.001) and preoperative myocardial infarction (P less than 0.05) were the best predictors of recurrent angina. In the long term, recurrent angina remains a problem, although this may change with the increased use of mammary-arterial grafts.

Actuarial Analysis↗
PubMed1989

Evolution and transcription of old world monkey globin genes.

Although apparently inactive in the whole animal, the delta globin genes from three species of Old World monkey (rhesus, baboon and green monkey) are all functional in an in vitro transcription assay. Their activities in vitro are similar to that of the functional human delta gene. A fourth monkey gene, from the colobus monkey, is transcribed approximately fivefold less efficiently than the others. This reduced in vitro activity results from a 20 base-pair deletion, which removes the normal site of mRNA initiation. When the deletion is repaired by site-directed mutagenesis, transcriptional activity increases to the level observed for the other delta genes. We also report the complete nucleotide sequences of the colobus beta, colobus delta, and rhesus delta genes. Sequence comparisons show that the delta and beta genes in the same species have not exchanged genetic information since the divergence of the human and monkey lineages. Phylogenetic analysis of these sequences affirms that the Old World monkey delta genes are evolving more rapidly than their functional counterparts. Moreover, the rate of replacement substitutions has risen to equal that of non-coding DNA, as expected for genes no longer under selective constraint.

Amino Acid Sequence↗
PubMed1989

Nucleotide sequence and genomic organization of bird minisatellites.

Two minisatellite loci from a Eurasian songbird, the willow warbler (Phylloscopus trochilus) were isolated, sequenced and used as probes to detect more than 20 related hypervariable loci. In addition, a sequence flanking one of the minisatellite loci was isolated, and used to study a VNTR locus. The bird minisatellites have a repeat unit of either 12 (AGGGAAGGGCTC) or 17 bp (GGGGACAGGGGACACCC), repeated in tandem 40-100 times per locus, and shows partial similarity to the sequence motifs of human minisatellites. These sequences are among the most variable minisatellites known, with the incidence per gamete of new length alleles estimated from family studies of warblers to about 5.6% per locus. The bird minisatellite alleles show mendelian inheritance and segregation analysis indicates that they are derived from families of sequences with members on several autosomal linkage groups. Some of the warbler core sequences cross-hybridize to hypervariable loci in other species of birds, mammals and fishes.

Alleles↗
PubMed1989

Episodic evolution in the stomach lysozymes of ruminants.

By sequencing lysozymes c from deer and pig stomachs and comparing them to the known amino acid sequences of other lysozymes c, it was possible to examine the rate of sequence change during and after the period in which this enzyme acquired a new function. Evolutionary tree analysis suggests that the rate went up while lysozyme was being recruited to function as a digestive enzyme in the stomach of early ruminants. Later, presumably after lysozyme was well adapted for functioning in the new environment, which contains acid, pepsin, and fermentation products, the rate of amino acid replacement became subnormal.

Adaptation, Physiological↗
PubMed1989

Preparative isoelectric focusing in ampholine electrofocusing columns versus immobiline polyacrylamide gel for the purification of biologically active leukoregulin.

Preparative vertical and rotating horizontal (Rotofor) ampholine column and immobiline flat bed polyacrylamide gel isoelectric focusing were evaluated for the isolation of the biologically active acidic form of leukoregulin, a 50,000-Da glycoprotein lymphokine with tumor growth inhibitory activity. Leukoregulin secreted by normal human lymphocytes was concentrated by 10,000 nominal molecular weight size exclusion ultrafiltration and by DEAE anion exchange chromatography using step elution with 0.02 M Tris-HCl: 0.1 M NaCl, pH 7.4. Preparative isoelectric focusing was carried out in a 110-ml vertical column containing 1% ampholines in a pH 4-6 gradient at 15 W constant power for 16-18 h, in a Rotofor 55-ml horizontal column containing 2% ampholines in a pH 4-6 gradient at 12 W constant power for 4-6 h, or in an immobiline pH 4.5-6.5 gradient within a 5% polyacrylamide 120 X 110 X 5-mm flat bed gel at 3 W constant power for 16-18 h. Recovery of biologically active leukoregulin from the vertical and horizontal ampholine columns was similar. The pH 4.9-5.2 fractions from the Rotofor ampholine column contained 4-7% and the fractions from the immobiline gel contained 4% of the leukoregulin activity applied to the electrofocusing column or gel, respectively. Analytical immobiline isoelectric focusing of the leukoregulin in the pH 4.9-5.2 fractions from the Rotofor column demonstrated that a single silver staining band with a pI of 5.1 can be obtained by this rapid method of preparative isoelectric focusing.

Acrylamides↗
PubMed1989

Dynamics of mitochondrial DNA evolution in animals: amplification and sequencing with conserved primers.

With a standard set of primers directed toward conserved regions, we have used the polymerase chain reaction to amplify homologous segments of mtDNA from more than 100 animal species, including mammals, birds, amphibians, fishes, and some invertebrates. Amplification and direct sequencing were possible using unpurified mtDNA from nanogram samples of fresh specimens and microgram amounts of tissues preserved for months in alcohol or decades in the dry state. The bird and fish sequences evolve with the same strong bias toward transitions that holds for mammals. However, because the light strand of birds is deficient in thymine, thymine to cytosine transitions are less common than in other taxa. Amino acid replacement in a segment of the cytochrome b gene is faster in mammals and birds than in fishes and the pattern of replacements fits the structural hypothesis for cytochrome b. The unexpectedly wide taxonomic utility of these primers offers opportunities for phylogenetic and population research.

Amino Acid Sequence↗
PubMed1989

Mitochondrial DNA sequences in single hairs from a southern African population.

Hypervariable parts of mitochondrial DNA (mtDNA) were amplified enzymatically and sequenced directly by using genomic DNA from single plucked human hairs. This method has been applied to study mtDNA sequence variation among 15 members of the !Kung population. A genealogical tree relating these aboriginal, Khoisan-speaking southern Africans to 68 other humans and to one chimpanzee has the deepest branches occurring amongst the !Kung, a result consistent with an African origin of human mtDNA. Fifteen cases of unrelated individuals having identical sequences in the most variable parts of the mtDNA control region were found within populations of !Kung, Western Pygmies, and Eastern Pygmies, but no cases of identity were evident among these populations. This and other evidence of geographic structuring of the mitochondrial diversity in Africa, together with knowledge of the rate of accumulation of base changes in human mtDNA, implies that the average rate at which female lineages have moved their home bases during hunter-gatherer times could be as low as 13 meters per year. The technique of enzymatic amplification and direct sequencing applied to readily collected, highly stable biological materials such as hairs makes it possible to examine with high resolution many representatives of virtually any population.

Africa, Southern↗
PubMed1989

Patterns of ribosomal RNA evolution in salamanders.

Sequence comparisons are presented for four segments of the large subunit of ribosomal RNA, including divergent domains D7a and D7b, portions of the large divergent domains D2, D3, and D8, and evolutionarily conservative sequences flanking divergent domains. These results resolve phylogenetic relationships among exemplars of seven families of salamanders and the three amphibian orders. Phylogenetic analysis confirms the prediction that divergent domains feature the highest relative rates of base substitution and length variation within the ribosome, but the divergent domains evolve more slowly than nuclear noncoding DNA and the silent sites of structural genes. Base substitutions demonstrate approximately twice as many transitions as transversions and an uneven distribution among sites within the divergent domains but no apparent bias in base composition. Length mutations are primarily small insertions and deletions, with deletions predominating. The divergent domains appear to be a good source of phylogenetic information for evolutionary events occurring approximately 100-200 million years ago.

Animals↗
PubMed1989

Atracurium overdose in a small infant.

An error in setting a syringe driver caused a 2.75 kg infant to receive 37 mg atracurium over 75 minutes. Clinically full recovery of muscle power had returned spontaneously 135 minutes after the infusion was stopped. The child suffered no ill effects. Assay of blood and urine for atracurium and laudanosine confirmed rapid clearance of the drug.

Atracurium↗
PubMed1989

Shifting constraints on tRNA genes during mitochondrial DNA evolution in animals.

During the evolution of echinoderm mitochondrial (mt) DNA, a transfer RNA gene lost its tRNA function and became part of a protein-coding gene. To examine the evolutionary consequences of this event, we sequenced 961 bp of mtDNA in five sea urchin species. This enabled us to build a tree relating the mtDNAs and use it for analyzing the pattern and process of evolutionary substitutions in the former leucine tRNA gene, which now is a 5' extension of the gene for NADH dehydrogenase subunit 5 (ND5). This 5' extension is now evolving at the same rate and under the same protein-coding constraints as the rest of ND5. The adjacent (upstream) serine tRNA gene, however, has been evolving at a reduced rate, consistent with the possibility that it has assumed a punctuation role in processing of the primary transcript that was once fulfilled by the former leucine tRNA gene.

Animals↗
PubMed1989

Weak beta-adrenoceptor-mediated relaxation in the human internal mammary artery.

The function of beta-adrenoceptors in the human internal mammary artery was studied in vitro to predict the way in which the internal mammary artery graft would respond to beta-adrenergic agonists and antagonists given in the perioperative period. Ring segments of the distal internal mammary artery obtained from patients not receiving beta-blocker therapy were mounted in organ baths and isometric wall force was measured. For comparison, similar experiments were conducted on segments of canine coronary artery, a vessel known to have powerful beta-adrenoceptor function. All arteries were precontracted with potassium or the thromboxane mimetic agent, U46619, before isoproterenol cumulative concentration-relaxation curves were constructed. In the human internal mammary artery, the maximum relaxation induced by isoproterenol was only 14% of the potassium-induced contraction and 24% of the U46619-induced contraction. These responses were weak compared with 54% and 86% for beta-adrenoceptor relaxation measured in corresponding experiments in the canine coronary artery. In all experiments, propranolol antagonized the relaxation induced by isoproterenol. These studies suggested that the human internal mammary artery has only a small number of beta-adrenoceptors. We conclude that beta-adrenoceptors would contribute little to the reactivity of the human internal mammary artery graft to sympathomimetic drugs.

Animals↗
PubMed1988

Loss of metastatic and primary tumor factor X activator capabilities by Lewis lung carcinoma cells cultured in vitamin K-dependent protein deficient serum.

A highly metastatic line of Lewis lung tumor cells established in fetal bovine serum (10%) was subcultured into normal rodent (mouse or rat) serum or rodent serum made deficient in functional vitamin K-dependent proteins (barium sulfate adsorption or warfarin treatment of animals). Following injection of cells cultured in normal rodent serum into C57BL/6 mice, Factor X activator activity in the primary tumors increased at a near linear rate per gram tumor and attained 5- to 8-fold higher levels than did cells grown in either of the deficient sera. Secondary lung foci were also visible in all mice of the normal-rodent serum groups within 10 days after injection, and by 21 days extensive tumor growth in the lungs had developed. No secondary lung foci were apparent in any mice of the deficient serum groups throughout 21 days of tumor burden. Cells cultured in nonrodent serum (fetal bovine serum) were less proficient than cells grown in normal mouse serum in developing primary tumor Factor X activator activity and producing secondary tumors. Exposure of cells cultured in barium sulfate-treated mouse serum to normal mouse serum for 3 h and 3 weeks prior to injection partially restored primary tumor Factor X activator and metastatic competence. These data strongly suggest that in Lewis lung tumor cells at least one species selective, plasma/serum vitamin K-dependent protein plays a major role in the regulation of metastatic events and demonstrate that there is a positive correlation between primary tumor Factor X activation activity and metastasis.

Animals↗
PubMed1988

Mitochondrial DNA sequences from a 7000-year old brain.

Pieces of mitochondrial DNA from a 7000-year-old human brain were amplified by the polymerase chain reaction and sequenced. Albumin and high concentrations of polymerase were required to overcome a factor in the brain extract that inhibits amplification. For this and other sources of ancient DNA, we find an extreme inverse dependence of the amplification efficiency on the length of the sequence to be amplified. This property of ancient DNA distinguishes it from modern DNA and thus provides a new criterion of authenticity for use in research on ancient DNA. The brain is from an individual recently excavated from Little Salt Spring in southwestern Florida and the anthropologically informative sequences it yielded are the first obtained from archaeologically retrieved remains. The sequences show that this ancient individual belonged to a mitochondrial lineage that is rare in the Old World and not previously known to exist among Native Americans. Our finding brings to three the number of maternal lineages known to have been involved in the prehistoric colonization of the New World.

Anthropology↗
PubMed1988

Conformational mutation in human mtDNA detected by direct sequencing of enzymatically amplified DNA.

Restriction enzyme analysis of 241 human mtDNAs revealed polymorphism in the electrophoretic mobility of a fragment corresponding to part of the ND4 gene. Enzymatic amplification and direct sequencing of this fragment demonstrates that a single T--C transition correlates with the faster mobility exhibited by the fragment in seven mtDNAs from Papua New Guinea. The enhanced mobility caused by this transition could result from disrupting an AT-rich region near the middle of the fragment that might make it curve. An analogous mutation at an adjacent position in a European mtDNA causes a similar but more pronounced alteration in mobility. The seven New Guineans with this substitution are all from the Eastern Highlands Province and constitute one clade in a genealogical tree based upon restriction analysis. The additional information provided by sequencing allows refinement of the genealogical tree but does not require modification of higher order branching structure.

Base Sequence↗
PubMed1988

Prognostic significance of ventricular ectopic activity in survivors of acute myocardial infarction who receive propranolol.

Beta blockers are frequently prescribed for survivors of acute myocardial infarction (AMI). Although ventricular ectopic activity was found to be associated with mortality in several cohorts, there are no data on the relation of ventricular ectopic activity to mortality in patients with AMI who receive beta blockers. One thousand six hundred and fifty participants in the Beta-Blocker Heart Attack Trial who were randomized to receive propranolol (60 or 80 mg 3 times daily) had 24-hour ambulatory electrocardiography at baseline. By multivariate analysis considering 16 variables, ventricular ectopic activity was independently associated with sudden death (p = 0.02 to 0.001) and total mortality (p = 0.04 to 0.0001) for an average follow-up of 25 months. By univariate analysis, ventricular ectopic activity was associated with increased total mortality (odds ratios 2.13 to 3.54) and sudden death mortality (odds ratio 2.26 to 3.93). The association of ventricular ectopic activity with mortality was observed in both high- and low-risk patient subsets with odds ratios similar to the placebo group. Thus, treatment with propranolol does not alter the relation between ventricular ectopic activity and mortality.

Analysis of Variance↗