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Biomedical subjects

C S Baker

Publications and source records attributed to C S Baker.

51 records · Page 3Linked to original sources
PubMed1993

Frequency and specificity of antiheart antibodies in patients with dilated cardiomyopathy detected using SDS-PAGE and western blotting.

OBJECTIVES: This study was designed to investigate the organ and disease specificity of antiheart antibodies in patients with dilated cardiomyopathy. BACKGROUND: Autoimmune disease is characterized by the presence of circulating autoantibodies, and autoimmune mechanisms may play a role in the pathogenesis of dilated cardiomyopathy. METHODS: An SDS-PAGE (sodium dodecylsulfate polyacrylamide gel electrophoresis) procedure followed by Western blotting was used to screen serum samples for antiheart antibodies of two immunoglobulin classes, IgM and IgG, from 52 patients with dilated cardiomyopathy and 48 patients with ischemic heart disease as control subjects. Use of two-dimensional gel electrophoresis followed by Western blotting and protein sequencing enabled us to identify the protein bands against which antiheart antibodies were produced in both groups of patients. RESULTS: Strong IgG antiheart antibodies against myocardial proteins, cross-reacting with skeletal muscle proteins, were detected in significantly more patients with dilated cardiomyopathy (n = 24 [46%]) than with ischemic heart disease (n = 8 [17%]) (p = 0.001). Patients with dilated cardiomyopathy showed a significantly greater frequency and reactivity of IgG antiheart antibodies against six myocardial proteins (molecular weight 30, 35, 40, 60, 85 and 200 kD) than did patients with ischemic heart disease. These were identified as myosin light chain 1, tropomyosin, actin, heat shock protein (HSP)-60, an unidentified protein and myosin heavy chain, respectively. CONCLUSIONS: We detected strong IgG antiheart antibodies in significantly more patients with dilated cardiomyopathy than with ischemic heart disease. The most immunogenic band was that corresponding to HSP-60. Antibodies against HSP-60 were found in 85% and 42% of patients with dilated cardiomyopathy and ischemic heart disease, respectively, confirming our hypothesis of an immune involvement in dilated cardiomyopathy.

Actins↗
PubMed1993

Abundant mitochondrial DNA variation and world-wide population structure in humpback whales.

Hunting during the last 200 years reduced many populations of mysticete whales to near extinction. To evaluate potential genetic bottlenecks in these exploited populations, we examined mitochondrial DNA control region sequences from 90 individual humpback whales (Megaptera novaeangliae) representing six subpopulations in three ocean basins. Comparisons of relative nucleotide and nucleotype diversity reveal an abundance of genetic variation in all but one of the oceanic subpopulations. Phylogenetic reconstruction of nucleotypes and analysis of maternal gene flow show that current genetic variation is not due to postexploitation migration between oceans but is a relic of past population variability. Calibration of the rate of control region evolution across three families of whales suggests that existing humpback whale lineages are of ancient origin. Preservation of preexploitation variation in humpback whales may be attributed to their long life-span and overlapping generations and to an effective, though perhaps not timely, international prohibition against hunting.

Animals↗
PubMed1991

Evaluation of membranes used for electroblotting of proteins for direct automated microsequencing.

Protein purification and characterisation have been age-old problems for the biochemist. A new era has arisen with the advent of one- and two-dimensional gel electrophoresis and high sensitivity automated protein microsequencing. These two tools along with electroblotting have made it possible to separate and analyse complex protein mixtures. We studied six different membranes compatible with Edman degradation chemistry to determine their efficiencies at binding proteins electroblotted from one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Their overall blotting-sequencing properties were also evaluated. We found that the polyvinylidene difluoride-based membranes out-performed the glass-based and polypropylene-based membranes under our selected experimental conditions. The problems associated with electroblotting and microsequencing are discussed.

Buffers↗
PubMed1990

Influence of seasonal migration on geographic distribution of mitochondrial DNA haplotypes in humpback whales.

Humpback whales (Megaptera novaeangliae) migrate nearly 10,000 km each year between summer feeding grounds in temperate or near-polar waters and winter breeding grounds in shallow tropical waters. Observations of marked individuals suggest that major oceanic populations of humpback whales are divided into a number of distinct seasonal subpopulations which are not separated by obvious geographic barriers. To test whether these observed patterns of distribution and migration are reflected in the genetic structure of populations, we looked for variation in the mitochondrial DNA of 84 individual humpback whales on different feeding and wintering grounds of the North Pacific and western North Atlantic oceans. On the basis of restriction-fragment analysis, we now report a marked segregation of mitochondrial DNA haplotypes among subpopulations as well as between the two oceans. We interpret this segregation to be the consequence of maternally directed fidelity to migratory destinations.

Animals↗
PubMedDate not supplied

A human myocardial two-dimensional electrophoresis database: protein characterisation by microsequencing and immunoblotting.

This communication briefly describes how a human heart two-dimensional electrophoresis (2-DE) protein database is being established in our laboratory. The database contains more than 1500 polypeptides and approximately fifty proteins from 2-DE gels of human myocardial tissue have been characterised. Information about the proteins has been compiled including molecular weight (M(r)), isoelectric point (pI), sample spot (SSP) number, protein name, partial sequence, and antibody reacting with the protein. The first stage of this project involves the investigation of protein with pIs in the range pH 4-7. Future studies will employ immobilised pH gradient (IPG) gels as the first dimension of the 2-DE to examine basic proteins. The ultimate goal of this project is to establish a global picture of human heart protein expression in both normal and disease conditions.

Amino Acid Sequence↗
PubMedDate not supplied

The effect of differential reproductive success on population genetic structure: correlations of life history with matrilines in humpback whales of the gulf of maine.

To examine whether demographic and life-history traits are correlated with genetic structure, we contrasted mtDNA lineages of individual humpback whales (Megaptera novaeangliae) with sighting and reproductive histories of female humpback whales between 1979 and 1995. Maternal lineage haplotypes were obtained for 323 whales, either from direct sequencing of the mtDNA control region (n = 159) or inferred from known relationships along matrilines from the sequenced sample of individuals (n = 164). Sequence variation in the 550 bp of the control region defined a total of 19 maternal lineage haplotypes that formed two main clades. Fecundity increased significantly over the study period among females of several lineages among the two clades. Individual maternal lineages and other clades were characterized by significant variation in fecundity. The detected heterogeneity of reproductive success has the potential to substantially affect the frequency and distribution of maternal lineages found in this population over time. There were significant yearly effects on adult resighting rates and calf survivorship based on examination of sighting histories with varying capture-recapture probability models. These results indicate that population structure can be influenced by interactions or associations between reproductive success, genetic structure, and environmental factors in a natural population of long-lived mammals.

Animals↗
PubMedDate not supplied

DNA surveillance: web-based molecular identification of whales, dolphins, and porpoises.

DNA Surveillance is a Web-based application that assists in the identification of the species and population of unknown specimens by aligning user-submitted DNA sequences with a validated and curated data set of reference sequences. Phylogenetic analyses are performed and results are returned in tree and table format summarizing the evolutionary distances between the query and reference sequences. DNA Surveillance is implemented with mitochondrial DNA (mtDNA) control region sequences representing the majority of recognized cetacean species. Extensions of the system to include other gene loci and taxa are planned. The service, including instructions and sample data, is available at http://www.dna-surveillance.auckland.ac.nz.

Animals↗
PubMedDate not supplied

A comprehensive and validated molecular taxonomy of beaked whales, family Ziphiidae.

DNA sequences from orthologous loci can provide universal characters for taxonomic identification. Molecular taxonomy is of particular value for groups in which distinctive morphological features are difficult to observe or compare. To assist in species identification for the little known family Ziphiidae (beaked whales), we compiled a reference database of mitochondrial DNA (mtDNA) control region (437 bp) and cytochrome b (384 bp) sequences for all 21 described species in this group. This mtDNA database is complemented by a nuclear database of actin intron sequences (925 bp) for 17 of the 21 species. All reference sequences were derived from specimens validated by diagnostic skeletal material or other documentation, and included four holotypes. Phylogenetic analyses of mtDNA sequences confirmed the genetic distinctiveness of all beaked whale species currently recognized. Both mitochondrial loci were well suited for species identification, with reference sequences for all known ziphiids forming robust species-specific clades in phylogenetic reconstructions. The majority of species were also distinguished by nuclear alleles. Phylogenetic comparison of sequence data from "test" specimens to these reference databases resulted in three major taxonomic discoveries involving animals previously misclassified from morphology. Based on our experience with this family and the order Cetacea as a whole, we suggest that a molecular taxonomy should consider the following components: comprehensiveness, validation, locus sensitivity, genetic distinctiveness and exclusivity, concordance, and universal accessibility and curation.

Actins↗
PubMedDate not supplied

Genetic variation of southern hemisphere fur seals (Arctocephalus spp.): investigation of population structure and species identity.

We have examined phylogenetic and geographic patterns of variation in the mitochondrial cytochrome b gene of Southern Hemisphere fur seals (Arctocephalus spp.). Our survey of 106 individuals from four putative species reveals three distinct patterns of variation reflecting ancient, recent historic, and contemporary gene flow. For the combined samples of Subantarctic (Arctocephalus tropicalis) and Antarctic (Arctocephalus gazella) fur seals, we find low levels of sequence diversity and reciprocal paraphyly of hapiotypes (where representative haplotypes of a species are found to occur infrequently in another species and vice versa). For the Australian and Cape fur seal subspecies (Arctocephalus pusillus doriferus and A. p. pusillus, respectively), we find low levels of sequence diversity but significant differences in the regional distribution of haplotypes that are consistent with, but not conclusive of, the current subspecies definition based on nonmolecular data. For the New Zealand fur seal (Arctocephalus forsteri), we find high levels of average sequence diversity because of the survival of two divergent lineages of mitochondrial hapiotypes with differences approaching that found in interspecific comparisons of other mammals. The two divergent clades are distributed sympatrically in some regions, but the overall geographic structure of the variation is significant across the range of this species. These new molecular data are inconsistent with current taxonomic definitions of species within the Southern Hemisphere fur seals and argue for reevaluation of these "species" definitions. For management purposes, the definition of evolutionarily significant units (Ryder 1986) and genetic management units (Moritz 1994) in relation to these species may also be evaluated in light of this molecular genetic information.

Animals↗
PubMedDate not supplied

Population characteristics of DNA fingerprints in humpback whales (Megaptera novaeangliae).

Humpback whales exhibit a remarkable social organization that is characterized by seasonal long-distance migration (> 10,000 km/year) between summer feeding grounds in high latitudes and winter calving and breeding grounds in tropical or near-tropical waters. All populations are currently considered endangered as a result of intensive commercial exploitation during the last 200 years. Using three hypervariable minisatellite DNA probes (33.15, 3'HVR, and M13) originally developed for studies of human genetic variation, we examined genetic variation within and among three regional subpopulations of humpback whales from the North Pacific and one from the North Atlantic oceans. Analysis of DNA extracted from skin tissues collected by biopsy darting from free-ranging whales revealed considerable variation in each subpopulation. The extent of this variation argues against a recent history of inbreeding among humpback whales as a result of nineteenth- and twentieth-century hunting. A canonical variate analysis suggested a relationship between scaled genetic distance, based on similarities of DNA fingerprints, and geographic distance (i.e., longitude of regional subpopulation). Significant categorical differences were found between the two oceanic populations using a multivariate analysis of variance (MANOVA) with a modification of the Mantel nonparametric permutation test. The relationship between DNA fingerprint similarities and geographic distance suggests that nuclear gene flow between regional subpopulations within the North Pacific is restricted by relatively low rates of migratory interchange between breeding grounds or assortative mating on common wintering grounds.

Animals↗
PubMedDate not supplied

Versatile fluid-mixing device for cell and tissue microgravity research applications.

Microgravity life-science research requires hardware that can be easily adapted to a variety of experimental designs and working environments. The Biomodule is a patented, computer-controlled fluid-mixing device that can accommodate these diverse requirements. A typical shuttle payload contains eight Biomodules with a total of 64 samples, a sealed containment vessel, and a NASA refrigeration-incubation module. Each Biomodule contains eight gas-permeable Silastic T tubes that are partitioned into three fluid-filled compartments. The fluids can be mixed at any user-specified time. Multiple investigators and complex experimental designs can be easily accommodated with the hardware. During flight, the Biomodules are sealed in a vessel that provides two levels of containment (liquids and gas) and a stable, investigator-controlled experimental environment that includes regulated temperature, internal pressure, humidity, and gas composition. A cell microencapsulation methodology has also been developed to streamline launch-site sample manipulation and accelerate postflight analysis through the use of fluorescent-activated cell sorting. The Biomodule flight hardware and analytical cell encapsulation methodology are ideally suited for temporal, qualitative, or quantitative life-science investigations.

Cell Culture Techniques↗
PubMedDate not supplied

Management of a perforated endotracheal tube during orthognathic surgery.

Oral and maxillofacial procedures require nasotracheal intubation that often obscures the anesthesiologist's direct vision of the surgical field. Premature extubation of a damaged endotracheal tube frequently requires replacement and poses a potential risk to the patient. This case illustrates a technique for replacing a damaged endotracheal tube using a nasogastric tube inserted within the damaged tube to suction secretions, insufflate oxygen, and serve as a guide for placement of a new endotracheal tube.

Adult↗
PubMedDate not supplied

Genetic impact of an unusual group mortality among humpback whales.

Mass mortalities, due to infectious disease or toxic algal blooms, are known to have severe demographic impacts on marine mammal populations. The genetic impacts of these events, however, have received little attention. To investigate the genetic consequences of an unusual group mortality among humpback whales, we compared the mitochondrial DNA haplotypes of 10 whales poisoned by mackerel contaminated with a dinoflagellate neurotoxin to those of 32 live whales from the same regional population. Two haplotypes that were rare in the reference sample of live whales accounted for eight of the 10 poisoned whales. A randomized test of independence, based on 500 permutations of the data matrix, showed significant differences in the frequencies of haplotypes in the two samples (P < .002). This is the first demonstration that group mortality events in marine mammals can have unpredictable genetic consequences and points to a need to evaluate ecological disasters within the context of the genetic mosaic of natural populations.

Animals↗