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At least 325 records · Page 18Linked to original sources
PubMed1980

Reversible (G0) and nonreadily reversible (Q) noncycling cells in human peripheral blood. Immunological, structural, and biological characterization.

PHA-stimulated human lymphocytes (normal-resting-proliferating) at 0, 24, 48, 72, and 144 h were studied with Acridine Orange (AO) staining. By viable cell sorting, by subsequent subculturing, and by the use of biochemical, biophysical, and immunological assays, not only have the G0 resting and G1 (cycling) cell cycle phases been objectively characterized, but a separate subpopulation of quiescent cells that are functionally viable and deeply committed to nonproliferation, the Q cells, has been identified. Multiparameter cytofluorimetric analysis, methyl14C-thymidine incorporation, automated image analysis, and mitogen stimulation studies have shown that the "Q" cell, compared to the "G0" resting but easily recruitable cell, exhibits quite lower red and green AO emission, possesses 2c to 4c DNA content (rather than only 2c), has a higher average optical density, and is either nonrecruitable or recruitable-with-difficulty in PHA-stimulated lymphocyte cultures.

Acridine Orange↗
PubMed1999

Complete reversal of run-down in rabbit cardiac Ca2+ channels by patch-cramming in Xenopus oocytes; partial reversal by protein kinase A.

The rabbit cardiac Ca2+ channel (alpha1C) expressed in Xenopus oocytes exhibited a complete run-down of ionic currents when cell-attached patches were excised. The alpha1C channel was expressed alone or was coexpressed with the accessory beta2a or beta1b subunit. The catalytic subunit of protein kinase A (PKAc) and MgATP were capable of delaying the run-down of single-channel currents. In 33% of the alpha1C patches, and 26% of the alpha1C+beta2a patches, inclusion of PKAc in the bath solution delayed the run-down for a maximum of 20 min. In experiments where PKAc in the bath was not sufficient to delay the run-down of channel activity, insertion of the patch back into the oocyte (patch-cramming) could restore channel activity. Gating currents were also measured in the alpha1C+beta1b channel and were not subject to any run-down, even after the complete run-down of ionic currents. The results presented here reveal that PKAc is capable of delaying the run-down of currents in a subset of patches. The patch-cramming results suggest that a cytoplasmic factor, in addition to phosphorylation of the channel (by PKAc), may be involved in the maintenance of channel activity.

Adenosine Triphosphate↗
PubMed1993

Chloroquine resistance in Plasmodium falciparum is not reversed by BIBW-22, a compound reversing the multidrug resistance phenotype in mammalian cancer cells.

The pteridine derivative BIBW-22 (4-[N-(2-hydroxy-2-methyl-propyl)-ethanolamino]-2,7-bis(cis-2,6-di methyl-morpholino)-6-phenylpteridine), which had been developed for the treatment of multidrug-resistant cancer and binds to P-glycoprotein, was tested against chloroquine resistant Plasmodium falciparum strains in culture. Based on the result that BIBW-22 enhanced rather than lowered chloroquine resistance in vitro, it is concluded that chloroquine resistance in malaria parasites may not be mechanistically linked to the multidrug-resistant phenotype of chloroquine resistant P. falciparum.

Animals↗
PubMed1985

Vasopressin pressor antagonist injected centrally reverses behavioral effects of peripheral injection of vasopressin, but only at doses that reverse increase in blood pressure.

Previous work in rats (Ader, R. and De Wied, D., Psychon. Sci., 29 (1972) 46-48) has established that subcutaneously (s.c.) injected arginine vasopressin (AVP) prolongs extinction of active avoidance and that this effect could be prevented by pretreatment with the vasopressin antagonist analog [1-deaminopenicillamine, 2-(O-methyl)tyrosine]-beta-arginine vasopressin (dPtyr(Me)AVP). The purpose of the present study was to determine if peripherally administered AVP acts via a peripheral blood pressure effect or by a direct action in the central nervous system. We therefore tested the effects of the antagonist injected intracerebroventricularly (i.c.v.) on the prolongation of active avoidance and on blood pressure effects of s.c. injected AVP. The antagonist (i.c.v.) blocked the behavioral effects of systemically injected AVP only at dose sufficient to block the peripherally mediated pressor response of systemically administered AVP. The results show that peripherally injected AVP acts on peripheral systems and support our hypothesis that the peripheral visceral action of AVP contributed significantly to its behavioral action.

Animals↗
PubMed2000

Hormone replacement therapy reverses the decrease in natural killer cytotoxicity but does not reverse the decreases in the T-cell subpopulation or interferon-gamma production in postmenopausal women.

OBJECTIVE: To investigate the immunologic deviations of postmenopausal women before and after hormone replacement therapy (HRT). DESIGN: Prospective study. SETTING: University teaching hospital. PATIENT(S): Seventeen postmenopausal women (study group) and 17 women of reproductive age (control group). INTERVENTION(S): Continuous usage of E(2) valerate 2 mg/d and medroxyprogesterone acetate 5 mg/d in postmenopausal women in the study group. MAIN OUTCOME MEASURE(S): Immunophenotyping with flow cytometry, cytokine production with and without mitogen stimulation of the peripheral mononuclear cells, and a natural killer (NK) cell cytotoxicity test against K562 target cells by the (51)Cr-release assay were performed in the control group and in the study group before, 1 month after, and 6 months after HRT. RESULT(S): NK cytotoxicity, interferon-gamma production, and the T-cell subpopulation were significantly decreased, and the subpopulations of CD3(+)CD25(+) and CD3(+)HLA-DR(+) were increased in the study group before HRT when compared with those in the control group. After HRT was given for 6 months, however, the NK cytotoxicity increased significantly in the postmenopausal women to a value similar to that of the control group. CONCLUSION(S): Women after menopause are prone to impaired immune responses. Nevertheless, some of the impairment can be restored after HRT.

Adult↗
PubMed1999

Semi-permeable surface analytical reversed-phase column for the improved trace analysis of acidic pesticides in water with coupled-column reversed-phase liquid chromatography with UV detection. Determination of bromoxynil and bentazone in surface water.

The coupled-column (LC-LC) configuration consisting of a 3 microm C18 column (50 x 4.6 mm I.D.) as the first column and a 5 microm C18 semi-permeable-surface (SPS) column (150 x 4.6 mm I.D.) as the second column appeared to be successful for the screening of acidic pesticides in surface water samples. In comparison to LC-LC employing two C18 columns, the combination of C18/SPS-C18 significantly decreased the baseline deviation caused by the hump of the co-extracted humic substances when using UV detection (217 nm). The developed LC-LC procedure allowed the simultaneous determination of the target analytes bentazone and bromoxynil in uncleaned extracts of surface water samples to a level of 0.05 microg/l in less than 15 min. In combination with a simple solid-phase extraction step (200 ml of water on a 500 mg C18-bonded silica) the analytical procedure provides a high sample throughput. During a period of about five months more than 200 ditch-water samples originating from agricultural locations were analyzed with the developed procedure. Validation of the method was performed by randomly analyzing recoveries of water samples spiked at levels of 0.1 microg/l (n=10), 0.5 microg/l (n=7) and 2.5 microg/l (n=4). Weighted regression of the recovery data showed that the method provides overall recoveries of 95 and 100% for bentazone and bromoxynil, respectively, with corresponding intra-laboratory reproducibilities of 10 and 11%, respectively. Confirmation of the analytes in part of the samples extracts was carried out with GC-negative ion chemical ionization MS involving a derivatization step with bis(trifluoromethyl)benzyl bromide. No false negatives or positives were observed.

Benzothiadiazines↗
PubMed1999

High throughput detection of retrovirus-associated reverse transcriptase using an improved fluorescent product enhanced reverse transcriptase assay and its comparison to conventional detection methods.

The development and application of a novel, sensitive TaqMan fluorescent probe-based product enhanced RT test (F-PERT) for the detection of retrovirus are described. The assay allows discrimination between the amplification signals generated by genuine positive signals that result from retroviral RT activity and the RT-like activity from DNA polymerases. The RT-like activity from DNA polymerases was suppressed by the addition of activated calf-thymus DNA with no reduction in the RT activity. A linear relationship between threshold cycle (C(T)) and the number of virus particles was demonstrated, allowing quantification of retroviruses in unknown samples. The F-PERT assay was able to detect a wide range of retroviral RT activities, including that from porcine endogenous retrovirus (PoERV), murine leukaemia virus (MLV), simian foamy virus (SFV), simian immunodeficiency virus (SIVmac) and squirrel monkey retrovirus (SMRV). The detection limit of SMRV, MLV and PoERV was approximately 100 virion particles and the test was able to detect at least 10(2) molecules of purified RT enzyme. RT activity was not detected in cellular lysates and supernatants from MRC-5, BT, VERO, or Raji cells, whereas RT activity was detected in C1271, Mus dunni, K-Balb, BHK-21, CHO-K1, SP2/0-Ag14 and NSO cell supernatants. RT activity was also detected in the Spodoptera cell line Sf9.

Animals↗