Influx rate of 18F-fluoroaminosuberic acid reflects cystine/glutamate antiporter expression in tumour xenografts

AbstractThe Oort cloud probably is the source of Halley-type (HT) comets and perhaps of some Jupiter-family (JF) comets. The process of capture of Oort cloud comets into HT comets by planetary perturbations and its efficiency are very important problems in comet ary dynamics. A small fraction of comets coming from the Oort cloud − of about 10−2− are found to become HT comets (orbital periods < 200 yr). The steady-state population of HT comets is a complex function of the influx rate of new comets, the probability of capture and their physical lifetimes. From the discovery rate of active HT comets, their total population can be estimated to be of a few hundreds for perihelion distancesq <2 AU. Randomly-oriented LP comets captured into short-period orbits (orbital periods < 20 yr) show dynamical properties that do not match the observed properties of JF comets, in particular the distribution of their orbital inclinations, so Oort cloud comets can be ruled out as a suitable source for most JF comets. The scope of this presentation is to review the capture process of new comets into HT and short-period orbits, including the possibility that some of them may become sungrazers during their dynamical evolution.

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Determination of cerebral glucose transport and metabolic kinetics by dynamic MR spectroscopy

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1997.273.6.e1216 ◽

1997 ◽

Vol 273 (6) ◽

pp. E1216-E1227 ◽

Cited By ~ 6

Author(s):

P. C. M. Van Zijl ◽

D. Davis ◽

S. M. Eleff ◽

C. T. W. Moonen ◽

R. J. Parker ◽

...

Keyword(s):

Glucose Transport ◽

Kinetic Equations ◽

Direct Determination ◽

Life Time ◽

Compartment Model ◽

Brain Extract ◽

Influx Rate ◽

Positron Emission

A new in vivo nuclear magnetic resonance (NMR) spectroscopy method is introduced that dynamically measures cerebral utilization of magnetically labeled [1-13C]glucose from the change in total brain glucose signals on infusion. Kinetic equations are derived using a four-compartment model incorporating glucose transport and phosphorylation. Brain extract data show that the glucose 6-phosphate concentration is negligible relative to glucose, simplifying the kinetics to three compartments and allowing direct determination of the glucose-utilization half-life time [ t ½ = ln2/( k 2 + k 3)] from the time dependence of the NMR signal. Results on isofluorane ( n = 5)- and halothane ( n = 7)- anesthetized cats give a hyperglycemic t ½ = 5.10 ± 0.11 min−1 (SE). Using Michaelis-Menten kinetics and an assumed half-saturation constant Kt = 5 ± 1 mM, we determined a maximal transport rate T max = 0.83 ± 0.19 μmol ⋅ g−1 ⋅ min−1, a cerebral metabolic rate of glucose CMRGlc = 0.22 ± 0.03 μmol ⋅ g−1 ⋅ min−1, and a normoglycemic cerebral influx rate CIRGlc = 0.37 ± 0.05 μmol ⋅ g−1 ⋅ min−1. Possible extension of this approach to positron emission tomography and proton NMR is discussed.

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BNP7787, a novel protector against platinum-related toxicities, does not affect the efficacy of cisplatin or carboplatin in human tumour xenografts

European Journal of Cancer ◽

10.1016/s0959-8049(02)00036-9 ◽

2002 ◽

Vol 38 (8) ◽

pp. 1148-1156 ◽

Cited By ~ 29

Author(s):

E Boven ◽

M Verschraagen ◽

T.M Hulscher ◽

C.A.M Erkelens ◽

F.H Hausheer ◽

...

Keyword(s):

Human Tumour ◽

Human Tumour Xenografts ◽

Tumour Xenografts

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Patient-derived tumour xenografts as models for oncology drug development

Nature Reviews Clinical Oncology ◽

10.1038/nrclinonc.2012.61 ◽

2012 ◽

Vol 9 (6) ◽

pp. 338-350 ◽

Cited By ~ 713

Author(s):

John J. Tentler ◽

Aik Choon Tan ◽

Colin D. Weekes ◽

Antonio Jimeno ◽

Stephen Leong ◽

...

Keyword(s):

Drug Development ◽

Oncology Drug ◽

Oncology Drug Development ◽

Tumour Xenografts

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The influx rate of long-period comets in the Earth's neighborhood and their debris contribution to the interplanetary medium

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314005006 ◽

2012 ◽

Vol 10 (H16) ◽

pp. 140-140

Author(s):

Julio Angel Fernández

Keyword(s):

Steady State ◽

Interplanetary Medium ◽

Interplanetary Dust ◽

Large Contribution ◽

Influx Rate ◽

Long Period ◽

Impact Rate ◽

Total Magnitude ◽

Dust Complex ◽

The Impact

AbstractWe analyze the flux of new and evolved long-period comets (LPCs) reaching the Earth's neighborhood (perihelion distances q < 1.3 AU), their physical lifetimes, and their implications as regards to the amount of meteoritic matter that is being deposited in the near-Earth region. The flux of LPCs with q < 1.3 au is found to be of about 340 ± 40, brighter than absolute total magnitude 8.6 (radius R ~ 0.6 km) (Fernández and Sosa 2012). Bearing in mind that most of these comets disintegrate into meteoritic matter, this represents a large contribution to the interplanetary dust complex which requires an amount of matter of about 10 tons s−1 to keep it in steady state. These aspects, as well as the impact rate with Earth of meteoroids of LPC origin, will be discussed in this presentation.

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Sodium Movements in the Human Red Blood Cell

The Journal of General Physiology ◽

10.1085/jgp.56.3.322 ◽

1970 ◽

Vol 56 (3) ◽

pp. 322-341 ◽

Cited By ~ 48

Author(s):

John R. Sachs

Keyword(s):

Blood Cell ◽

Rate Constant ◽

Transport Mechanism ◽

Extracellular Potassium ◽

Sodium Influx ◽

Influx Rate ◽

High K ◽

Inner Surface ◽

Pump Mechanism ◽

Made In

Measurements were made of the sodium outflux rate constant, okNa, and sodium influx rate constant, ikNa, at varying concentrations of extracellular (Nao) and intracellular (Nac) sodium. okNa increases with increasing [Nao] in the presence of extracellular potassium (Ko) and in solutions containing ouabain. In K-free solutions which do not contain ouabain, okNa falls as [Nao] rises from 0 to 6 mM; above 6 mM, okNa increases with increasing [Nao]. Part of the Na outflux which occurs in solutions free of Na and K disappears when the cells are starved or when the measurements are made in solutions containing ouabain. As [Nao] increases from 0 to 6 mM, ikNa decreases, suggesting that sites involved in the sodium influx are becoming saturated. As [Nac] increases, okNa at first increases and then decreases; this relation between okNa and [Nac] is found when the measurements are made in high Na, high K solutions; high Na, K-free solutions; and in (Na + K)-free solutions. The relation may be the consequence of the requirement that more than one Na ion must react with the transport mechanism at the inner surface of the membrane before transport occurs. Further evidence has been obtained that the ouabain-inhibited Na outflux and Na influx in K-free solutions represent an exchange of Nac for Nao via the Na-K pump mechanism.

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