Biomedical subjects
I Kramer
Publications and source records attributed to I Kramer.
T cell receptor/CD3 and CD28 use distinct intracellular signaling pathways.
Ligation of the T cell membrane antigen CD28 strongly enhances cytokine secretion in human T lymphocytes that are activated via T cell receptor (TcR)/CD3 or CD2 molecules. This study was undertaken to investigate whether, as has been indicated for activation via TcR/CD3, stimulation via CD28 is dependent on the activation of protein kinase C (PKC). Two inhibitors of PKC, 1-alkyl 2-methyl-glycerol and staurosporine, caused a dose-dependent inhibition of T cell proliferation induced by anti-CD3 monoclonal antibodies (mAb). The induction of interleukin (IL) 2 secretion was found to be more sensitive to the effects of the PKC inhibitors than the up-regulation of IL 2 receptor expression. In marked contrast, the anti-CD28 mAb-mediated enhancement of T cell proliferation and IL 2 secretion were insensitive to the action of either compound. We conclude that two independent signaling pathways may be operational in human T cells. The first used by TcR/CD3 depends on the activation of PKC, whereas the second is employed by CD28 and functions independently of PKC.
[Physical characteristics of endometric instruments].
A method for measuring and documentation of the physical characteristics of electronic root canal length determination instruments is presented and illustrated by evaluation of ten different devices. Important parameters such as the influence of the capacitive component in alternating current resistances are presented by means of impedance-charts. All devices examined worked with alternating current; regarding frequency, signal form and resistances, which the devices interpreted as "Apex", the measurements obtained varied. The advantages of this method for clinical and experimental studies are discussed by the author.
Muscle involvement in mucolipidosis IV.
A 15-month-old boy, thought to have a congenital myopathy, was subsequently diagnosed as having mucolipidosis type IV, with typical membranous inclusions in muscle fibers. Involvement of skeletal muscle in this lysosomal storage disease may explain the motor delay and hypotonia that are its most common presenting signs.
[Studies on the pharmacokinetics and biotransformation of ipratropium bromide in the rat and dog].
The pharmacokinetics of the bronchodilator (8r)-3alpha-hydroxy-8-isopropyl-1alphaH,5alphaH-tropanium-bromide-(+/-)-tropate (ipratropiumbromide, Sch 1000, Atrovent) were studied in the rat and the dog after administering radioactive material (14C). The blood level of Sch 1000 following oral dosing showed plateaus in both the rat and the dog over a period of 2--8 h following administration. Subsequent elimination from the blood occurs with a half-life of 7h (rat) and 10 (dog). The half-life of elimination following i.v. administration is 1.9 h (rat) and 3.4 h (dog). In the rat biliary excretion occurs to the extent of 3.2% following oral dosing and 17.7% following i.v. application. In the same species renal excretion is 5.5% following oral administration and 58% following i.v. administration. Renal excretion in the dog, on the other hand, averaged 28% following oral and 55% following i.v. dosing, respectively. On the basis of a comparison of the areas under the blood level curves and also from the renal excretion following oral and i.v. dosing, i.e. disregarding absorption by gastrointestinal tissue, absorption was calculated as being 12% in the rat and 38% in the dog. Absorption in the rat after 1--3 h was calculated at 17--35% including the gastrointestinal tissue. Four metabolites and the unchanged substance could be detected in the 8-h urine of the rat. In the urine of the dog, the percentage of unchanged substance fell from a maximum of 81% (after 1 h) to 20% (after 47 h) in terms of radioactivity in the urine.
[Whole-body autoradiographic studies on the distribution and the placental transfer of fenoterol-hydrobromide (Th 1165a) in rats].
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[On the influence of hydroxyenals (4-hydroxypent-2,3-trans-en-1-al) on DNA and RNA of Ehrlich ascites tumor cells].
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[On the binding of alpha, beta-unsaturated aldehydes to cells and tissues].
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