Tracer Studies of Neuroreceptor Kinetics In Vivo

2019 ◽  
pp. 63-82
Author(s):  
Albert Gjedde
Keyword(s):  
Tracer Studies ◽  
Kinetics In Vivo

Neutrophil kinetics in rabbits during infusion of zymosan-activated plasma

1989 ◽  
Vol 67 (1) ◽  
pp. 88-95 ◽  
Author(s):  
C. M. Doerschuk ◽  
M. F. Allard ◽  
J. C. Hogg
Keyword(s):  
Relative Size ◽  
Pulmonary Sequestration ◽  
Blood Velocity ◽  
Pulmonary Capillaries ◽  
In Vitro Activation ◽  
The Complement System ◽  
Kinetics In Vivo ◽  
Neutrophil Kinetics

Complement activation in vivo produces neutropenia and pulmonary sequestration of neutrophils (PMNs) whereas in vitro activation increases PMN adherence and decreases PMN deformability. The present study examined PMN kinetics in vivo to determine if this sequestration was specific to the lung. Venous or arterial injections of radiolabeled PMNs were given to animals receiving infusions of zymosan-activated plasma (ZAP) or saline, and the PMN distribution was evaluated 10 min later. In control animals, the relative size of the marginated and circulating PMN pools was similar after venous or arterial injection and regional PMN retention increased as blood velocity slowed. ZAP infusion produced threefold increases in PMNs within pulmonary capillaries after venous injection and PMN retention was independent of blood velocity. After arterial injection, ZAP infusion produced PMN sequestration in all organs. Rigid (glutaraldehyde-fixed) PMNs injected into control rabbits showed increased lung recoveries similar to those of fresh PMNs injected into ZAP-treated rabbits. We conclude that activation of the complement system causes PMN sequestration in both the pulmonary and the systemic microvasculature and that the decrease in PMN deformability that occurs with activation of the PMN may be important in the genesis of PMN sequestration.

Dose-response curves of effects of insulin on leucine kinetics in humans

1986 ◽  
Vol 251 (3) ◽  
pp. E334-E342 ◽  
Author(s):  
P. Tessari ◽  
R. Trevisan ◽  
S. Inchiostro ◽  
G. Biolo ◽  
R. Nosadini ◽  
...  
Keyword(s):  
Insulin Infusion ◽  
Leucine Incorporation ◽  
Dependent Manner ◽  
Carbon Oxidation ◽  
Response Curves ◽  
Leucine Kinetics ◽  
Dose Dependent ◽  
Kinetics In Vivo ◽  
Infusion Period

To determine the effects of physiological and pharmacological insulin concentrations on leucine-carbon kinetics in vivo, eight postabsorptive normal volunteers were infused with L-[4,5-3H]leucine and alpha-[1-14C]ketoisocaproate (KIC). Insulin concentrations were sequentially raised from 8 +/- 1 to 43 +/- 6 and 101 +/- 14 and to 1,487 +/- 190 microU/ml, while maintaining euglycemia with adequate glucose infusions. At the end of each 140-min insulin-infusion period, steady-state estimates of leucine and KIC rates of appearance (Ra), KIC (approximately leucine-carbon) oxidation, nonoxidized leucine-carbon flux [an index of leucine incorporation into protein (Leu----P)], and leucine and KIC interconversion rates were obtained. After the three insulin infusions, leucine Ra decreased by a maximum of approximately 20%. KIC Ra decreased by a maximum of approximately 50%. The sum of leucine plus KIC Ra in the basal state was 2.59 +/- 0.24 mumol X kg-1 X min-1 and decreased by approximately 30% at the maximal insulin concentrations. KIC oxidation decreased by a maximum of approximately 65%. Leu----P did not increase after hyperinsulinemia. Interconversion rates were promptly and markedly suppressed by 50-70%. Leucine clearance increased by approximately 120%. We conclude that euglycemic hyperinsulinemia, at physiological and pharmacological concentrations, decreased leucine and KIC concentrations, leucine-carbon turnover and oxidation, and leucine and KIC interconversions in a dose-dependent manner in vivo.

Smooth Muscle Cell Kinetics in Vivo: A Comparative Study

1980 ◽  
pp. 567-569
Author(s):  
Michael B. Stemerman ◽  
Itzhak D. Goldberg ◽  
Ruth T. Gardner ◽  
Robert L. Fuhro
Keyword(s):  
Smooth Muscle ◽  
Comparative Study ◽  
Smooth Muscle Cell ◽  
Muscle Cell ◽  
Cell Kinetics ◽  
Kinetics In Vivo

scholarly journals Measurement of Eosinophil Kinetics In Vivo

2021 ◽  
pp. 183-191
Author(s):  
Neda Farahi ◽  
Daniel Gillett ◽  
Chrystalla Loutsios ◽  
A. Michael Peters ◽  
Charlotte Summers ◽  
...  
Keyword(s):  
Kinetics In Vivo

A Model Mechanism for the Enzymatic Synthesis of Lupin Alkaloids

1979 ◽  
Vol 34 (9-10) ◽  
pp. 704-708 ◽  
Author(s):  
Michael Wink ◽  
Thomas Hartmann ◽  
Hans-M artin Schiebel
Keyword(s):  
Enzyme System ◽  
Cell Suspension Cultures ◽  
Gas Liquid Chromatography ◽  
Alkaloid Biosynthesis ◽  
Tracer Studies ◽  
Lupinus Polyphyllus ◽  
Crude Enzyme Preparation ◽  
Enzymatic Model ◽  
Hypothetical Mechanism

Abstract A crude enzyme preparation obtained from cell suspension cultures of Lupinus polyphyllus catalyzes the pyruvate dependent conversion of cadaverine into the tetracyclic lupin alkaloids. As the first reaction product 17-oxosparteine could be identified by gas-liquid chromatography and mass spectroscopy. In some experiments sparteine was found additionally. A participation of di­amine oxidase could be ruled out. The cadaverine-pyruvate transaminating enzyme system (17-oxosparteine synthase) catalyzes the formation of 17-oxosparteine from three cadaverine units without releasing free intermediates. These results are inconsistent with the hypothetical mechanism thus far formulated for the lupin alkaloid biosynthesis. A new enzymatic model mechanism is proposed regarding both the results of the enzymatic experiments and those of the in vivo tracer studies.

scholarly journals Surfactant-Associated Protein B Kinetics In Vivo in Newborn Infants by Stable Isotopes

2005 ◽  
Vol 57 (4) ◽  
pp. 519-522 ◽  
Author(s):  
Paola Cogo ◽  
Aldo Baritussio ◽  
Federica Rosso ◽  
Antonina Gucciardi ◽  
Vincenzo Moretti ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Newborn Infants ◽  
Kinetics In Vivo ◽  
Protein B

scholarly journals Kinetics of adult hematopoietic stem cell differentiation in vivo

2018 ◽  
Vol 215 (11) ◽  
pp. 2815-2832 ◽  
Author(s):  
Samik Upadhaya ◽  
Catherine M. Sawai ◽  
Efthymia Papalexi ◽  
Ali Rashidfarrokhi ◽  
Geunhyo Jang ◽  
...  
Keyword(s):  
Stem Cell Differentiation ◽  
Cell Types ◽  
Lineage Tracing ◽  
Intermediate Cell ◽  
Hematopoietic Stem ◽  
Hematopoietic Stem Cell Differentiation ◽  
Kinetics Of ◽  
Kinetics In Vivo

Adult hematopoiesis has been studied in terms of progenitor differentiation potentials, whereas its kinetics in vivo is poorly understood. We combined inducible lineage tracing of endogenous adult hematopoietic stem cells (HSCs) with flow cytometry and single-cell RNA sequencing to characterize early steps of hematopoietic differentiation in the steady-state. Labeled cells, comprising primarily long-term HSCs and some short-term HSCs, produced megakaryocytic lineage progeny within 1 wk in a process that required only two to three cell divisions. Erythroid and myeloid progeny emerged simultaneously by 2 wk and included a progenitor population with expression features of both lineages. Myeloid progenitors at this stage showed diversification into granulocytic, monocytic, and dendritic cell types, and rare intermediate cell states could be detected. In contrast, lymphoid differentiation was virtually absent within the first 3 wk of tracing. These results show that continuous differentiation of HSCs rapidly produces major hematopoietic lineages and cell types and reveal fundamental kinetic differences between megakaryocytic, erythroid, myeloid, and lymphoid differentiation.

scholarly journals Direct arene C–H fluorination with 18F− via organic photoredox catalysis

Science ◽  
2019 ◽  
Vol 364 (6446) ◽  
pp. 1170-1174 ◽  
Author(s):  
Wei Chen ◽  
Zeng Huang ◽  
Nicholas E. S. Tay ◽  
Benjamin Giglio ◽  
Mengzhe Wang ◽  
...  
Keyword(s):  
Pharmaceutical Compounds ◽  
Emission Tomography ◽  
Light Illumination ◽  
Photoredox Catalysis ◽  
Tracer Studies ◽  
Drug Discovery And Development ◽  
Positron Emission ◽  
Wide Range ◽  
Diagnostic Agents

Positron emission tomography (PET) plays key roles in drug discovery and development, as well as medical imaging. However, there is a dearth of efficient and simple radiolabeling methods for aromatic C–H bonds, which limits advancements in PET radiotracer development. Here, we disclose a mild method for the fluorine-18 (18F)–fluorination of aromatic C–H bonds by an [18F]F− salt via organic photoredox catalysis under blue light illumination. This strategy was applied to the synthesis of a wide range of 18F-labeled arenes and heteroaromatics, including pharmaceutical compounds. These products can serve as diagnostic agents or provide key information about the in vivo fate of the labeled substrates, as showcased in preliminary tracer studies in mice.

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