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Biomedical subjects

T K Gartner

Publications and source records attributed to T K Gartner.

At least 55 records · Page 3Linked to original sources
PubMed1983

TFP inhibits the expression of the endogenous platelet lectin and secretion of alpha-granules.

Activated platelets that have not undergone secretion do not express the endogenous platelet lectin whereas activated platelets that have undergone secretion do express this lectin. Expression of the lectin, secretion of beta-TG and PF-4, and secondary aggregation are inhibited by TFP. These results demonstrate that expression of the endogenous platelet lectin is apparently secretion dependent. Our results also reveal that inhibition of platelet aggregation by TFP apparently is not caused by inhibition of secretion and that there are TFP sensitive and TFP insensitive mechanisms of secretion.

Beta-Globulins↗
PubMed1982

A novel method for purification of plasma fibronectin.

Plasma fibronectin was purified from a gelatin-affinity chromatography column by elution with glucose. This procedure was effective only if the gelatin was particulate when it was attached to the Sepharose 4B. Glucose could not elute fibronectin from the gelatin if the gelatin was melted before it was attached to the Sepharose 4B. This new purification technique has the advantage of using very mild conditions for the isolation of plasma fibronectin.

Chromatography, Affinity↗
PubMed1981

Fibrinogen is the receptor for the endogenous lectin of human platelets.

Washed platelets activated by alpha-thrombin, gamma-thrombin, thrombocytin or the ionophore A23187 (ref. 3) lose their disk shape, produce pseudopodia and become cohesive. This cohesiveness is accompanied by the expression of an endogeneous haemagglutinin which, although apparently bound to the platelet membrane, is dependent on cell secretion. The interaction of this agglutinin with appropriate receptors on other platelets is believed to be responsible for aggregation. We report here that platelets can be prepared which lack agglutinin activity but have receptor function, that afibrinogenaemic platelets lack receptor activity, and that fibrinogen is the receptor for the agglutinin secreted by activated platelets.

Blood Platelets↗
PubMed1981

The endogenous lectin of human platelets is an alpha-granule component.

Platelets from patients with several bleeding disorders (congenital afibrinogenemia, Glanzmann's thrombasthenia, gray platelet syndrome, and Hermansky-Pudlak syndrome) were evaluated for both platelet-bound and platelet-free hemagglutination activities. Thrombin and A23187 activated afibrinogenemic, Hermansky-Pudlak, and thrombasthenic platelets had normal platelet-bound hemagglutination activity. Gray platelets activated by the same agents had deficient platelet-bound hemagglutination activity. In contrast, thrombin-activated afibrinogenemic, gray, and thrombasthenic platelets lacked platelet-free hemagglutination activity. Only thrombin-activated Hermansky-Pudlak platelets had a normal level of platelet-free hemagglutination activity. On the basis of these results and the distinguishing characteristics of the defective platelets, it is concluded that the alpha-granules are the origin of the enhanced hemagglutination activity. Furthermore, it is suggested that the insufficiency of the platelet-bound agglutinin may be the cause of the inability of gray platelets to aggregate normally in response to thrombin.

Blood Coagulation Disorders↗
PubMed1978

Thrombin-induced platelet aggregation is mediated by a platelet plasma membrane-bound lectin.

Throbin-activated human platelets cause agglutination of trypsinized, formalinized bovine erythrocytes. This lectin activity of stimulated platelets was blocked by galactosamine, glucosamine, mannosamine, lysine, and arginine, but not by N-acetylated sugars, other neutral sugars, or other amino acids. Inhibitors of the thrombin-induced lectin activity also blocked thrombin-induced platelet aggregation. It appears that a membrane surface component that has lectin activity mediates platelet aggregation.

Agglutinins↗
PubMed1976

Genetic and physiological evidence concerning the development of chemically sensitive voltage-dependent inophores in L6 cells.

The electrophysiological properties of a tissue culture muscle line, L6, and a K+ resistant mutant (MK1) derived from L6 were determined to elucidate certain aspects of membrane differentiation and function. MK1 was selected as a clone of myoblasts resistant to the toxic effects of 55 mM K+. The resting potentials of L6 and MK1 myoblasts and myotubes were K+ dependent and equal. The amplitudes of the action potentials were equal in normal medium, but 27.7 mM K+ interfered with or eliminated the ability of L6 myotubes to produce action potentials. MK1 myotubes produced nearly normal action potentials under these conditions. Thus, the K+ resistant myoblasts differentiate into myotubes which have an action potential generating mechanism much less sensitive to K+ than the normal mechanism. Also, both d-tubocurarine and alpha-bungarotoxin enhance the amplitude of the action potentials produced by L6 myotubes in the presence of 27.7 mM K+; these compounds do not enhance the amplitude of the action potentials produced by MK1 myotubes under the same conditions. It is proposed that as a consequence of differentiation a type of ionophore present in myoblasts becomes a voltage-dependent inophore in myotubes. Furthermore, these voltage-dependent ionophores can be chemically sensitive.

Action Potentials↗
PubMed1972

Close linkage between ochre and missense suppressors in Escherichia coli.

It was previously shown that the ochre suppressor mutation sup15B in Escherichia coli determines the accumulation of altered 30S ribosomal subunits and the presence of altered transfer ribonucleic acid (tRNA) capable of suppressing in vitro the UAG codon. This mutation has been mapped in the present study by means of conjugation and transduction experiments. After establishing the location of sup15B near argH, the following order was determined for the markers tested: metB-argH-(sup15B, supA36)-rif-thi. A comparison of location, growth rate, and suppressor pattern determined by sup15B and supM indicates the high probability that both suppressor mutations are identical. This study has also yielded a more precise location for the rifampin resistance gene. The most interesting finding is the very close (if not adjacent) location of the suppressor mutations sup15B and supA36, both of which determine tRNA alterations.

Chromosome Mapping↗
PubMed1969

The molecular basis of suppression in an ochre suppressor strain possessing altered ribosomes.

Escherichia coli K12 2320(lambda)-15B has a mutation that results in ochre suppressor activity.(1) This mutation concomitantly causes a decreased growth rate in rich medium, an increased sensitivity to streptomycin,(1) and the production of some altered 30S ribosomes which are differentially sensitive to RNase.(2) The results presented below demonstrate that the molecules which cause suppression are tRNA. These observations justify the conclusions that the suppressor mutation did not occur in a structural gene for a ribosomal component, and that the decreased growth rate in rich medium, the increased sensitivity to streptomycin, and the production of altered 30S ribosomes are probably all secondary consequences of the suppressor mutation.

Coliphages↗
PubMed1966

Effects of mutations to streptomycin resistance on the rate of translation of mutant genetic information.

Gartner, T. K. (University of California, Santa Barbara), and E. Orias. Effects of mutations to streptomycin resistance on the rate of translation of mutant genetic information. J. Bacteriol. 91:1021-1028. 1966.-The effects of mutations to streptomycin resistance of independent origin upon the translation of suppressible mutant information were studied in an isogenic series of strains of Escherichia coli. The group of suppressible mutants included 1 mutation in the z gene of the lac operon of E. coli (O(0) (2) allele), 12 mutations distributed among the two rII cistrons of T4, and 13 mutations distributed among at least five cistrons of phage T7. It was concluded that the mutations to streptomycin resistance cause a significant decrease in the rate of translation of the suppressible codons, and that this effect is limited to a few types of codons.

Chromosome Mapping↗
PubMed1966

Suppression of amber and ochre rII mutants of bacteriophage T4 by streptomycin.

Orias, E. (University of California, Santa Barbara), and T. K. Gartner. Suppression of amber and ochre rII mutants of bacteriophage T4 by streptomycin. J. Bacteriol. 91:2210-2215. 1966.-Streptomycin-induced suppression of amber and ochre rII mutants of phage T4 was studied in a streptomycin-sensitive strain of Escherichia coli and four nearly isogenic streptomycin-resistant derivatives of this strain, in the presence and in the absence of an ochre suppressor. Most of the 12 rII mutants tested were suppressed by streptomycin in the streptomycin-sensitive su(-) strain. This streptomycin-induced suppression in the su(-) strain was eliminated by the independent action of at least two of the four nonidentical mutations to streptomycin resistance. In two of the su(+)str-r strains, streptomycin markedly augmented the suppression caused by the ochre suppressor. In those su(-)str-r hosts in which significant streptomycin-induced suppression could be measured, the amber mutants were more suppressible than the ochre mutants.

Chromosome Mapping↗