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Biomedical subjects

D R Barnett

Publications and source records attributed to D R Barnett.

At least 19 recordsLinked to original sources
PubMed1992

A problem-based learning approach to teaching medical genetics.

A newly developed problem-based medical genetics course that was integrated into the fourth-year medical school curriculum of the University of Texas Health Science Center at San Antonio is described. To provide a basic genetic background for the clinical rotations, a supplemental computer tutorial is required during the second year. These two formats prepare the medical students to recognize genetic diseases, to provide basic genetic counseling in their daily practice, and to appropriately refer patients to genetic specialists.

Computer-Assisted Instruction↗
PubMed1988

Haptoglobin.

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Chromatography, Affinity↗
PubMed1986

Characterization, mapping, and expression of the human ceruloplasmin gene.

Ceruloplasmin (CP) is a copper-binding protein in vertebrate plasma. It is the product of an intragenic triplication and is composed of three homologous domains. Oligonucleotide probes constructed according to published amino acid sequences were used to identify cDNA clones encoding human CP. Two clones, CP-1 and CP-2, differed from each other by the presence or absence, respectively, of a deduced sequence of four amino acids. The two clones provided 81% of the sequence encoding CP. Comparison of the nucleotides of the three domains of the CP coding sequence revealed internal domain homology with identity of sequences ranging from 50.1% to 56%. The nucleotide sequence of CP-2 cDNa was compared to that of a homologous human protein, clotting factor VIII, and was found to be 48% identical overall. The CP gene was mapped to human chromosome 3 by somatic-cell-hybrid analysis and to 3q25 by in situ hybridization; however, sites of hybridization to DNA on other chromosomal sites suggested additional CP-like DNA sequences in the human genome. A DNA polymorphism was detected with CP cDNA after endonuclease digestion of human DNA by Pst I. CP mRNA was detected in human liver, macrophages, and lymphocytes by in situ histohybridization.

Base Sequence↗
PubMed1986

Linkage of cystic fibrosis locus and polymorphic DNA markers in 14 families.

Linkage relationships between the cystic fibrosis (CF) locus and three polymorphic DNA markers were examined in 14 families, five of which were of Hispanic origin. Tight linkage was found between the CF locus and MET (maximum lod score = 7.16 at theta = .001), and between CF and pJ3.11 (maximum lod score = 3.87 at theta = .001). We observed two recombinations between CF and collagen, yielding a maximum lod score of 0.359 at theta = .125, and one recombination in the cluster CF-MET-pJ3.11. Analysis by the seriation method indicates the order COL-pJ3.11-CF-MET.

Cystic Fibrosis↗
PubMed1979

Altered polyamine metabolism in cystic fibrosis.

Children with cystic fibrosis excreted elevated urinary levels of all three polyamines--putrescine, spermidine, and spermine. Heterozygote parents excreted intermediate concentrations of the polyamines, but not levels significantly different from levels in normal controls. Patients with cystic fibrosis who were administered a tracer amount of [14C]spermidine excreted 11--13% of the radiolabel within 72 hr whereas normal controls excreted 60--76% of the radiolabel within 72 hr. Spermine excretion was positively correlated with increased pathology as assessed by the National Institutes of Health (NIH) clinical score, whereas urinary putrescine and spermidine levels were negatively correlated with increased pathology.

Adult↗
PubMed1977

Cystic fibrosis: studies with the oyster ciliary assay.

Bioassays using ciliary systems have detected a factor or factors in cystic fibrosis (CF) sera and tissue culture medium derived from CF cells. The typical shortcomings of an assay measuring biological activity have been studied, and the means to overcome the weaknesses of the oyster gill cilia assay have been established. The presence of the cystic fibrosis mucociliary inhibitor (CFMI) in experimental fractions may be determined by accepting data from only those assays in which authentic CF and normal (non-CF) fractions give defined reactions, by measuring the reaction of each sample at least three times, and by examining each experimental sample at a protein concentration greater than the minimum established in this study. The relative concentrations of the CFMI present in the first steps of purification of serum and medium have been calculated in terms of units of inhibition. Generally, the units of inhibition present in serum and medium fractions from heterozygotes are close to one-half of that in fractions from homozygous sources. Analogous fractions concentrated from a normal (non-CF) source never inhibited mucociliary activity, even when tested at nearly 100 times the CF concentration. Ciliary assays utilizing oyster gills are essential for monitoring fractionation procedures aimed at purifying the CFMI, and have been shown to be capable and reliable enough to do so.

Biological Assay↗
PubMed1976

Immunochemical studies of the plasma and cultured fibroblast media fractions containing the cystic fibrosis ciliary inhibitor.

The cystic fibrosis ciliary inhibitor (CFCI) has been fractionated from plasma of cystic fibrosis (CF) homozygotes and from the media of cultured fibroblasts derived from CF homozygotes. Plasma and fibroblast media from normal controls have been fractionated in an identical manner. Fractions from plasma and fibroblast culture media that demonstrate ciliary inhibitory activity contain several proteins in a molecular weight range of approximately 5,000-11,000. These proteins have been partially characterized by immunochemical analysis with antisera to 33 human serum proteins. Immunological determinants of albumin, C3 (but not C3a), C4, C5, alpha1-lipoprotein, beta-lipoprotein, beta2-microglobulin and immunoglobulin light chains have been detected by hemagglutination in fractions of CF plasma that inhibited ciliary activity and in analogous fractions from normal sera. None of the proteins were detected in media of cultured fibroblasts from either genotype. Since the same proteins and protein fragments were identified in both CF and normal plasma fractions, and were not detected in CF fibroblast media, it appears that none of these proteins can be identified as the CFCI. Identification of these proteins will permit further purification of the CFCI by immunochemical methods.

Animals↗
PubMed1976

Somatic cell genetic studies of cystic fibrosis.

The expression of the gene coding for the cystic fibrosis ciliary inhibitor has been examined in somatic cell hybrid clonal lines. Hybrids were produced by the fusion of cultured skin fibroblasts from cystic fibrosis patients with mouse RAG and LM (TK-) cell lines. The ciliary inhibitor was detected by the oyster ciliary assay in several primary hybrid clones but not detected in others, indicating the segregation of an associated nuclear gene.

Animals↗
PubMed1976

Electrophoretic studies of the cystic fibrosis ciliary inhibitor and its interaction with immunoglobulin G.

The cystic fibrosis ciliary inhibitor (CFCI) has been partially purified from serum and plasma of cystic fibrosis (CF) homozygotes and heterozygotes, and from media of cultured fibroblasts derived from cystic fibrosis genotypes. Characterization and comparison of fractions containing the CFCI were carried out by polyacrylamide gel electrophoresis. Gel electrophoresis confirmed previous molecular weight estimations of 4,500 to 11,000 for the CFCI and provided an estimate of the number of proteins present in the fractions. Low molecular weight proteins from serum and media were combined with IgG preparations. No specific binding to IgG by the media fraction containing the CFCI could be demonstrated by the techniques employed. There was decreased binding of the low molecular weight serum fraction containing CFCI to native IgG molecules from cystic fibrosis patients as compared to IgG from normal individuals. However, IgG from CF individuals demonstrated increased binding of the cfci-containing low molecular weight serum fraction after gel filtration in the presence of guanidinium chloride. This suggests: 1) that very low concentrations of CFCI are present in media fractions; and 2) that native CF IgG cannot bind the low molecular weight CFCI fractions to the same degree as native IgG from normals or CF IgG that has been dissociated from non-covalently bound components.

Blood Proteins↗
PubMed1973

Cystic fibrosis: fractionation of fibroblast media demonstrating ciliary inhibition.

A chromatographic fraction has been identified in media from fibroblast cultures derived from 15 of 18 cystic fibrosis patients and 8 of 10 heterozygotes that inhibits ciliary activity, as judged by the oyster gill assay. The analogous fraction of media from cultures of fibroblasts derived from 11 normal individuals did not inhibit ciliary activity under the experimental conditions used. The chromatographic fractions containing the ciliary inhibitory activity from both fibroblast media and sera of cystic fibrosis patients and heterozygotes eluted in the same position from diethylaminoethyl-cellulose at pH 8.5. Although the serum ciliary inhibitor had consistently been detected in a fraction that contained predominantly immunoglobulin G, results of the fractionation of fibroblast media demonstrate that the ciliary inhibitor is present in a protein fraction containing three species of different molecular weight and in which IgG cannot be detected by the techniques used.

Animals↗