Mean cell volume of human blood leucocytes and resident and activated murine macrophages

Nibbering, Peter H.; Zomerdijk, Timo P.L.; Tilburg, Adriana J. Corsèl-Van; Furth, R. van

doi:10.1016/0022-1759(90)90432-u

Cited by 59 publications

(38 citation statements)

References 8 publications

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“…Based on the calculated amounts of total Nrf2, Keap1, and Cul3 proteins in RAW 264.7 cells, the concentrations in the cytoplasm/organelles or nuclei were calculated using an estimate of the cell volume to be 460 femtoliters, and a nucleus/cytoplasm ratio of 0.54 for mouse peritoneal macrophages (41,42). In the cytoplasm/organelles of RAW 264.7 cells, Nrf2 was present at a low level in the basal state (149 nM) and increased up to 619 nM in the DEM-induced state.…”

Section: Resultsmentioning

confidence: 99%

Absolute Amounts and Status of the Nrf2-Keap1-Cul3 Complex within Cells

Iso

Suzuki

Baird

et al. 2016

Molecular and Cellular Biology

101

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The transcription factor Nrf2 (NF-E2-related-factor 2) is essential for the oxidative and electrophilic stress responses. Keap1 (Kelch-like-ECH-associated-protein 1), an adaptor for a cullin-3 (Cul3)-based ubiquitin ligase, regulates Nrf2 activity through proteasomal degradation, and acts as a sensor for oxidative and electrophilic stresses. The Keap1-Cul3 complex is a critical regulator of the cellular Nrf2 level, and yet quantitative information regarding their endogenous intracellular concentrations in homeostatic conditions and during stress responses is unknown. We analyzed the absolute amounts of the Nrf2, Keap1, and Cul3 proteins in five murine cell lines by comparison with serial dilutions of purified recombinant protein standards in combination with quantitative immunoblot analyses. In the basal state, the amount of Nrf2 was maintained at lower levels than those of Keap1 and Cul3 proteins, whereas the electrophilic agent diethylmaleate dramatically increased Nrf2 to a level greater than that of Keap1 and Cul3, resulting in the accumulation of Nrf2 in the nucleus. In contrast, Keap1 and Cul3 did not display any changes in their abundance, subcellular localization, or interaction in response to electrophilic stimuli. Our results demonstrate that the regulation of the Nrf2 protein level during stress responses is mediated by the activity but not the composition of the Nrf2-Keap1-Cul3 complex.

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Section: Resultsmentioning

confidence: 99%

Absolute Amounts and Status of the Nrf2-Keap1-Cul3 Complex within Cells

Iso

Suzuki

Baird

et al. 2016

Molecular and Cellular Biology

101

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“…The intracellular drug concentration in PBMCs (C PBMC ) was determined by the following formula: C PBMC ϭ (measured PBMC concentration/actual cell count for each sample)/(421 fl), where 421 fl is the mean PBMC volume (16). Serum sample preparation.…”

Section: Methodsmentioning

confidence: 99%

Absolute Bioavailability and Intracellular Pharmacokinetics of Azithromycin in Patients with Cystic Fibrosis

Beringer

Huynh

Kriengkauykiat

et al. 2005

Antimicrob Agents Chemother

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“…The results were expressed in micrograms per milliliter of the original (undiluted) sample. The volume of one monocyte was reported as 421 m 3 (15), and therefore the number of cells in a sample multiplied by 421 m 3 represented the total volume of cells before lysing. The ratio of cellular volume to sample volume was used to translate the results obtained in the bioassay into the intracellular concentration of the drug in micrograms per milliliter of the cell mass.…”

Section: Methodsmentioning

confidence: 99%

Comparison of activities of rifapentine and rifampin against Mycobacterium tuberculosis residing in human macrophages

Mor

Simon

Mezo

et al. 1995

Antimicrob Agents Chemother

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The activities of rifapentine and rifampin against Mycobacterium tuberculosis residing in human monocytederived macrophages were determined. The MICs and MBCs of rifapentine for intracellular bacteria were twoto fourfold lower than those of rifampin. For extracellular bacteria, this difference was less noticeable. Nevertheless, the more favorable pharmacokinetics of rifapentine over rifampin was addressed in other experimental models. These models showed substantial differences after short pulsed exposures of the infected macrophages to the drugs and when the infected macrophages were exposed to changing drug concentrations that imitated the pharmacokinetic curves observed in blood. Once-a-week exposures to rifapentine concentrations equivalent to those attained in blood after one 600-mg dose resulted during the first week in a dramatic decline in the number of bacteria, and this decline was maintained at a minimal level for a period of four weeks. The results of this study have shown the suitability of rifapentine for intermittent-treatment regimens. The prolonged effect of rifapentine found in this study may be associated with high ratios of intracellular accumulation, which were four-to fivefold higher than those found for rifampin. Further studies on the intracellular distribution of rifamycins and on the sites of actual interaction between the drugs and bacteria residing in macrophages are necessary.The combined use of isoniazid, rifampin, and pyrazinamide provided the basis for a successful short course of tuberculosis therapy. The discovery of long-lasting rifamycins, particularly of rifapentine (RPT), created the possibility for intermittent drug regimens (5,7,18). In the early studies, RPT was reported to have an in vitro activity the same as or higher than that of rifampin (RMP) (19,20). Subsequent studies have shown that the broth-determined MICs of RPT were two-to threefold lower than those of RMP (8, 10). The elimination half-life of RPT in animals and humans was about five times longer than that of RMP, and the levels of RPT in plasma substantially exceeded the MICs for a period of up to 72 h after a single oral dose (1)(2)(3)12). The advantage of RPT over RMP has been shown in murine models (1,5,11,18). Besides its more favorable pharmacokinetic parameters in blood, RPT accumulates to higher concentrations than does RMP in polymorphonuclear leukocytes and macrophages (6,9,16).In anticipation of a controlled clinical trial for the comparison of RPT and RMP in the therapy of tuberculosis, the present study compares the potential activities of these rifamycins against extracellular and intracellular Mycobacterium tuberculosis. Inhibitory and bactericidal activities (MICs and MBCs) against intracellular bacteria in human monocyte-derived macrophages were determined and compared with MICs and MBCs against extracellular bacteria. The actual accumulation of these drugs in human monocytes was also determined. Special attention was given to the evaluation of the long-lasting effect of RPT after pulsed expo...

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Mean cell volume of human blood leucocytes and resident and activated murine macrophages

Cited by 59 publications

References 8 publications

Absolute Amounts and Status of the Nrf2-Keap1-Cul3 Complex within Cells

Absolute Amounts and Status of the Nrf2-Keap1-Cul3 Complex within Cells

Absolute Bioavailability and Intracellular Pharmacokinetics of Azithromycin in Patients with Cystic Fibrosis

Comparison of activities of rifapentine and rifampin against Mycobacterium tuberculosis residing in human macrophages

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