Metabolitanalysen bei schnell wachsenden DS-Carcinosarkomen der H�hner-Chorioallantois

Rauen, H. M.; Norpoth, K.; Wenderdel, P.; Böhm, Elisabeth; Husen, N. van

doi:10.1007/bf00524799

Cited by 5 publications

(3 citation statements)

References 22 publications

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“…Multicellular tumor spheroids were cultured in media with elevated lactate concentrations to match the situation of cells in tumor micro-areas in vivo where metabolic wastes, such as lactic acid, are accumulated because of inadequate removal by an insufficient microcirculation (Rauen et al, 1969). Volume growth rates of the cellular aggregates were considerably retarded by elevated lactate concentrations, growth saturation occurred at much smaller spheroid diameters than in control conditions, and the clonogenicity of spheroid cells was reduced.…”

Section: Discussionmentioning

confidence: 99%

“…An objective of the present investigation was to study possible influence of elevated lactate levels on growth, viability, oxygenation status and respiratory activity of multicellular tumor spheroids, since lactate has been shown to accumulate substantially in tumor tissue up to concentrations of >20 mM (Rauen et al, 1969). Presumably, even proliferating cells next to tumor microvessels are exposed to elevated lactate concentrations, which can be concluded from high lactate concentrations in the range of 5-7 m~ found in tumor-venous blood (Vaupel et a l .…”

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confidence: 99%

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Biological response of multicellular emt6 spheroids to exogenous lactate

Bourrat-Floeck

Groebe

Mueller‐Klieser

1991

Intl Journal of Cancer

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The influence of elevated lactate concentrations, as found in tumor microregions, on cellular growth, viability, and metabolic state was studied employing the multicellular spheroid model. Spheroids of EMT6/Ro cells were cultured at 37 degrees C in 5% or 20% (v/v) oxygen, using stirred media with various concentrations of exogenous lactate ranging from 0.0 mM (standard conditions) to 20.0 mM. Elevated concentrations of exogenous lactate led to a considerable decrease of the maximum spheroid diameter at growth saturation, e.g., for 20% O2 from around 1700 microns to 700 microns in 0.0 and 20.0 mM lactate respectively. Histological investigations showed that the thickness of the viable cell rim was increased by elevated lactate concentrations in 20% O2, whereas this correlation was reversed in 5% O2. Cultivation of spheroids in increasing lactate concentrations was associated with a shift of metabolic pathways from net production to increased utilization of lactate in both 20% and 5% O2, as determined by standard enzymatic assays. Oxygen tension (PO2) values measured with micro-electrodes were less in spheroids cultured in high lactate (9.0 and 20.0 mM) than under standard conditions, irrespective of the external oxygen concentration. This finding reflected a substantial increase in the cellular O2 consumption with elevated external lactate levels. At given lactate concentrations, respiration rates that were derived from measured PO2 distributions by theoretical considerations were significantly lower in 5% O2 than in 20% O2.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Biological response of multicellular emt6 spheroids to exogenous lactate

Bourrat-Floeck

Groebe

Mueller‐Klieser

1991

Intl Journal of Cancer

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“…With these results, we believe that the propensity of 1 to form an iminooxazolidinone upon exposure to an isocyanate, in lieu of catalyzing an isocyanate cyclooligomerization reaction or forming a hydantoin, was driven by electronic effects. [65,66] Regardless, the aforementioned reaction constitutes the first example of selectively synthesizing an iminooxazolidinone, a pharmacologically relevant heterocyclic core, [67] instead of a hydantoin, which is frequently obtained from the introduction of a carbene (e.g., SIPh [19,20,22] or dimethoxycarbene [21,68,69] ) to an isocyanate. [70] To further compare the nucleophilic reactivity of DACs to other carbenes, 1 was treated with two equivalents of diphenylketene in C 6 D 6 ([1] 0 = 0.1 M) for 1 h (Scheme 4).…”

Section: Introductionmentioning

confidence: 99%

Exploring the nucleophilicity of N,N′‐diamidocarbenes: Heteroallenes and related compounds as coupling reagents

Lee

Moerdyk

Bielawski

2012

J of Physical Organic Chem

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The propensity of a stable N,N′‐diamidocarbene (DAC) to react with various heteroallenes was explored. The DAC condensed with 4‐nitrophenyl azide as well as 4‐nitrophenyl isothiocyanate to afford the respective acyclic triazene or zwitterionic dihydropyrimidinium imidothiolate products. Treating the DAC with two equivalents of 3‐nitrophenyl isocyanate afforded an iminooxazolidinone rather than the expected hydantoin. Similarly, the addition of diphenylketene to the DAC afforded a dioxolane product, whereas analogous reactions involving N‐heterocyclic carbenes (NHCs) resulted in betaine adducts. Although the DAC as well as various diaminocarbenes condensed with 2,6‐dimethoxyphenyl nitrile N‐oxide to afford the respective nitrosoethylenes, only the six‐membered DAC and NHC adducts rearranged to the corresponding nitrones at elevated temperature. Copyright © 2012 John Wiley & Sons, Ltd.

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