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Biomedical subjects

D B Wilson

Publications and source records attributed to D B Wilson.

At least 325 records · Page 18Linked to original sources
PubMed1978

Multiple-gated acquisition cardiac blood-pool isotope imaging. Evaluation of left ventricular function correlated with contrast angiography.

Thirty-one patients were assessed by the multiple-gated acquisition cardiac blood-pool isotope-imaging technique using radiolabeled albumin within 24 hours of biplane contrast ventriculography. Data from the imaging method were analyzed by a semiautomatic technique with computer-generated edge detection and background subtraction. An excellent correlation was observed between ejection fractions determined with multiple-gated isotope imaging and those obtained by biplane contrast ventriculography (r = 0.93), and the same was true for average ejection rates (r = 0.80). For assessment of wall motion with this imaging technique, the anterior and the left anterior oblique left ventricular views were divided into nine segments, and a score was assigned to each segment based on the degree of wall motion. The cumulative anterior and left anterior oblique scores correlated well with the score from biplane contrast ventriculography (r = 0.90), and in 94% of segments in the left anterior oblique projection the assessment with multiple-gated isotope imaging was the same as or varied by only one class from the assessment by biplane contrast ventriculography. The multiple-gated acquisition cardiac blood-pool isotope-imaging technique is thus a valuable noninvasive method for assessing left ventricular function as measured by ejection fraction, ejection rates, and wall motion.

Adult↗
PubMed1977

The control of specificity of cytotoxic T lymphocytes by the major histocompatibility complex (AG-B) in rats and identification of a new alloantigen system showing no AG-B restriction.

The regulatory influence of the rat major histocompatibility complex (MHC) (Ag-B complex) on the specificity of cytotoxic T lymphocytes was investigated. It was shown that the effector cells were specific for the original Ag-B phenotype in rat systems in which the responder and stimulator cell populations were unquestionably MHC identical but expressed different minor alloantigens of viral antigens. However, combined in vivo immunization and restimulation in culture of lymphocytes from rat strains previously thought to be MHC compatible resulted in the generation of cytotoxic T lymphocytes which effectively lyse not only target cells from the specific stimulating strains but also, to varying degrees, target cells from third party strains regardless of their Ag-B haplotypes. Genetic analysis indicates that expression of these cytotoxic T-cell-defined ("CT") antigens, found on both T and B lymphocytes, detectable thus far only with cytotoxic lymphocytes, is controlled by a single locus which segregates in backcross populations with the rat MHC. Discrepancies between the nature of CT antigens of the rat Ag-B and I-region specificities of the mouse H-2 are discussed.

Animals↗
PubMed1977

The generation of killer cells to trinitrophenyl-modified allogeneic targets by lymphocyte populations negatively selected to strong alloantigens.

Negatively selected mouse and rat lymphocyte populations, specifically deprived of alloreactivity to a particular major histocompatibility complex (MHC) haplotype, are nevertheless fully capable of responding to trinitrophenyl (TNP)-modified allogeneic stimulator cells and developing cytotoxic T-lymphocyte activity to TNP-altered allogeneic target cells. As for syngeneic systems, lytic expression of those responder killer cells also requires MHC identity between the target and stimulator cell populations. Such a finding argues strongly against two variations of the dual recognition hypothesis: like-like interactions and adaptive differentiation. Instead, these data favor either the altered self model or a third variation of the dual receptor model, where one of the relevent receptors is specific for the modifying antigen and the second is a low affinity receptor unable to be triggered in the absence of a modifying antigen.

Animals↗
PubMed1977

Cerebellar histogenesis in the lurcher (Lc) mutant mouse.

The postnatal development of the cerebellar cortex of normal and lurcher (Lc) mutant mice was studied by neurohistological and autoradiographic techniques at ages ranging from 2 days through 18 days after birth. Lurcher shows severe defects in the granule cells and Purkinje cells soon after birth. A decrease in the generative layers of the external granular layer is seen as early as two days in the lobulus simplex and by six days of age in the uvula. Granule cell death is common before and during granule cell migration, from 2 to 18 days of age. Loss of granule cells is reflected in reduced growth of the molecular and granular layers. Purkinje cell abnormalities appear at three to four days after birth in the form of crowding failure of nuclear growth, and condensed or lessened cytoplasm; Purkinje cell death is apparent at four to six days of age depending on the region of the cerebellum.

Age Factors↗
PubMed1977

Histocompatibility antigen-activated cytotoxic T lymphocytes. I. Estimates of the absolute frequency of killer cells generated in vitro.

A sensitive procedure employing limiting dilution of activated lymphocytes and 51Cr release from highly labeled target cells was used to derive minimal estimates of the absolute frequency of cytotoxic T lymphocytes (CTL) present in a population of mouse lymphocytes activated to alloantigens of the major histocompatibility complex in bulk mixed lymphocyte cultures. From this figure (0.7-1.2%), the maximal rate of target cell killing could be calculated to be approximately 4 targets/CTL/hour.

Animals↗
PubMed1977

Histocompatibility antigen-activated cytotoxic T lymphocytes. II. Estimates of the frequency and specificity of precursors.

Using limiting dilutions of responding cells in mouse mixed leukocyte cultures, we obtained direct estimates of the minimum frequency of precursors of cytotoxic T lymphocytes (CTL.P) for a variety of antigens. Depending on the strain combination, there were as many as 4-15 CTL.P reactive to DBA/2 among 10(4) lymph node cells. Taking into account that only 5-10% of peripheral T lymphocytes have the potential to develop into cytotoxic T lymphocytes (CTLs) (6), this implies that at least 1-2% of all CTL.P are responsive to any given H-2 haplotype difference. Precursors of cytotoxic cells thus have the same high frequency of cells reactive to alloantigens of the major histocompatibility complex as found among proliferating cells in graft-vs.-host reactions and mixed lymphocyte interactions. The frequencies of CTL.P reactive to xenoantigens (rat) or trinitrophenyl-modified self were less than half the frequency of alloreactive CTL.P. A minority of the CTL.P specific for one H-2 haplotype were also reactive to a third party H-2 haplotype, presumably on the basis of recognition of shared determinants. By dilution of sensitized cells from single microcultures, it was shown that a single CTL.P undergoes a minimum of three to four cell divisions and generates at least 8-16 CTLs after antigenic activation.

Animals↗
PubMed1977

Purification and properties of galactokinase from Saccharomyces cerevisiae.

Galactokinase (EC 2.7.1.6; ATP:D-galactose-1-phosphotransferase) was purified to homogeneity with a 50% yield from cells of Saccharomyces cerevisiae which were fully induced for the production of the galactose metabolizing enzymes. The purification was accomplished by:(a) ammonium sulfate fractionation, (b) streptomycin sulfate precipitation. (c) DEAE-cellulose chromatography, (d) hydroxylapatite chromatography, and finally (e) Bio-Gel A-0.5 m gel filtration. The resulting preparation of galactokinase was judged to be at least 95% pure by the following criteria: (a) sodium dodecyl sulfate-polyacrylamide gel electrophoresis, (b) ultracentrifuge analysis, (c) nondissociating polyacrylamide gel electrophoresis, and (d) Bio-Gel A-0.5 m gel filtration. The purified enzyme preparation was used to determine the Km values for the two substrates, galactose and ATP, which were found to be 0.60 and 0.15 mM, respectively. Vmax was also determined and found to be 3.35 mmol/h/mg. This corresponds to a turnover rate of 3350 molecules of galactose phosphorylated/min/enzyme molecule. The effect of pH on the galactokinase-catalyzed phosphorylation of galactose was determined; the results showed the pH optimum of the reaction to be in the range of pH 8.0 to 9.0. The enzyme is highly specific for galactose since galactokinase did not appear to phosphorylate any of the other sugars tested at a rate greater than 0.5% of the rate of galactose phosphorylation. Amino acid analysis was performed on the enzyme preparation and the results were used to calculate the partial specific volume (v) of 0.736. The NH2-terminal sequence was determined for the first 3 residues. The molecular weight and subunit composition were determined by ultracentrifugation and polyacrylamide gel electrophoresis under dissociating and nondissociating conditions. The data obtained indicated that galactokinase is a monomeric protein of molecular weight 58,000.

Amino Acid Sequence↗
PubMed1977

The induction of specific resistance in F1 hybrid rats to local graft-vs.-host reactions: nature of the eliciting cell.

A specific state of resistance to local graft-vs.-host (GVH) reactions can be induced in F1 hybrid rats, derived from Ag-B incompatible matings, as a consequence of inoculation with low numbers of parental strain lymphocytes. The magnitude of GVH resistance is markedly and directly dependent upon the number of parental strain lymphocytes used in the pretreatment regimen. The relevant constituents of the resistance-inducing parental cell population are thymus-derived (T) lymphocytes possessing immunologic competence for host alloantigens. B cells, themselves incapable of inducing GVH resistance, adversely effect the induction or display of this effect by T cells.

Animals↗
PubMed1977

Role of a sugar-lipid intermediate in colanic acid synthesis by Escherichia coli.

Membrane fractions from a lon strain of Escherichia coli but not a wild-type strain catalyze the incorporation of fucose from guanosine 5'-diphosphate-fucose into a lipid and into polymeric material. Both incorporation reactions specifically require only uridine 5'-diphosphate (UDP)-glucose. The sugar lipid was shown to be an intermediate in the synthesis of the polymer which was related to colanic acid. The sugar lipid had the structure (fucose3, glucose2)-glucose P-P-lipid. Its behavior on column and thin-layer chromatography, the rates of its hydrolysis in acid and base, and the response of its synthesis to inhibitors are all identical to the other sugar-lipid intermediates which have been shown to contain sugars attached to the C55-polyisoprenol, undecaprenol, by a pyrophosphate linkage. The membrane fractions from both the lon strain and the wild-type strain also catalyzed the incorporation of either glucose from UDP-glucose or galactose from UDP-galactose into a lipid fraction which was shown to contain the free sugar attached by a monophosphate linkage to an undecaprenol-like lipid. This lipid was isolated and its nuclear magnetic resonance spectra was identical to undecaprenol. The membrane fractions from both strains also incorporated glucose from UDP-glucose into glycogen and into a polymer that behaved like Escherichia coli lipopolysaccharide. Conditions were found where the incorporation of glucose could be directed specifically into each compound by adding the appropriate inhibitors.

Bacitracin↗
PubMed1977

Quantitative aspects of proliferation in the nasal epithelium of the rhesus monkey embryo.

Proliferation was studied in the nasal epithelium of rhesus monkey embryos ranging in age from 26 through 41 days of gestation (stages 13-20). Labeling indices were tabulated 1 h after an intrachorionic injection with [3H]thymidine, and the distribution of labeled cells was determined at intervals ranging from 1h to 11h after injection. The labeling index showed a chronological decrease from 69-4% in the nasal placode at stage 13 to 31-6% in the nasal pit at stage 20. The vomeronasal epithelium was distinctive in that the basal cells lost their ability to incorporate [3H]thymidine as early as stage 18. In the remainder of the nasal epithelium, mitotic figures were initially confined to apical regions but later occurred in basal regions as the embryonic pattern of proliferation became converted to the adult type.

Animals↗
PubMed1976

Sheep red blood cell-specific helper activity in rat thoracic duct lymphocyte populations positively selected for reactivity to specific strong histocompatibility alloantigens.

These studies show that positively selected T-cell populations, having enriched reactivity in the mixed lymphocyte interaction and the graft-versus-host reaction to strong alloantigens of a chosen major histocompatibility complex haplotype, also possess helper activity which is quantitatively normal in the generation of primary antibody responses to sheep red blood cells in vitro. Such positively selected populations give a linear dose plaque-forming cells response curve indistinguishable from that seen with normal unselected T-cell populations. These findings imply that T cells reactive to histocompatibility antigens also react to conventional antigens, and the possibility is raised that they may do so by some recognition mechanism involving multiple specificities.

Animals↗
PubMed1976

Feedlot manure top dressing for irrigated pasture: good agricultural practice or a health hazard?

Top dressing a spray-irrigated pasture of orchard-grass with 125 t/ha of overwintered beef feedlot manure almost doubled the yield of dry forage: 6353 kg/ha vs. 3578 kg/ha for the plots receiving no manure. Even at this rate of application, the manure did not contaminate the irrigated grass with enteropathogenic bacteria after irrigation. When the grass became contaminated through the use of fecally polluted irrigation water, the fecal coliforms, indicator organisms with survival characteristics similar to the salmonellae, were effectively eliminated from the grass after exposure to 65 hr of bright sunlight.

Agriculture↗