Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Neutral Red”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,369 records · Page 76Linked to original sources
PubMed1987

A role for early cytotoxic T cells in resistance to ectromelia virus infection in mice.

Ectromelia virus-specific cytotoxic T (Tc) cell precursors were present in the draining popliteal lymph node of all strains of mice tested at 2 to 3 days after footpad inoculation of a high dose (10(5) p.f.u.) of the virulent Moscow strain of ectromelia virus. To detect this response it was necessary to culture lymph node cells from infected mice in the presence of T cell growth factors and to use the more sensitive neutral red assay for measuring cytotoxicity. Cells with lytic activity were virus-specific, major histocompatibility complex-restricted TC cells. C57BL/6J resistant mice, which express a single dominant gene conferring innate resistance had virus-specific TC cell precursors 1 to 2 days sooner than did susceptible BALB/b mice. This TC cell-mediated immune response early after infection could account for the barrier to virus dissemination known to operate 1 to 2 days after infection to slow virus passage into the lymphoreticular system.

Animals↗
PubMed1996

Comparative cytotoxicity of purified Shiga-like toxin-IIe on porcine and bovine aortic endothelial and human colonic adenocarcinoma cells.

Porcine and bovine aortic endothelial cells and human colonic adenocarcinoma cells were compared for their susceptibility to the toxic effect of purified Shiga-like toxin IIe (SLT-IIe), measured by the neutral red cytotoxicity assay. Cytotoxicity correlated with toxin binding as indicated by fluorescence activated cell sorter analysis and with the globotriosylceramide (Gb3) and globotetraosylceramide (Gb4) content of cells determined by high pressure liquid chromatography. One line of porcine aortic endothelial cells was 1400-fold more susceptible than the line of bovine aortic endothelial cells that was tested, but a second line of porcine aortic endothelial cells was highly refractory to SLT-IIe. Human colonic adenocarcinoma cells lacked detectable levels of Gb4 and were least susceptible to SLT-IIe.

Adenocarcinoma↗
PubMed1994

Evidence for an Extracellular Reception Site for Abscisic Acid in Commelina Guard Cells.

The phytohormone abscisic acid (ABA) triggers stomatal closing as a physiological response to drought stress. Several basic questions limit an understanding of the mechanism of ABA reception in guard cells. Whether primary ABA receptors are located on the extracellular side of the plasma membrane, within the intracellular space of guard cells, or both remains unknown. Furthermore, it is not clear whether ABA must be transported into guard cells to exert control over stomatal movements. In the present study, a combination of microinjection into guard cells and physiological assays of stomatal movements have been performed to determine primary sites of ABA reception in guard cells. Microinjection of ABA into guard cells of Commelina communis L. resulted in injected cytosolic concentrations of 50 to 200 [mu]M ABA and in additional experiments in lower concentrations of approximately 1 [mu]M ABA. Stomata with ABA-loaded guard cells (n > 180) showed opening similar to stomata with uninjected guard cells. The viability of guard cells following ABA injection was demonstrated by neutral red staining as well as monitoring of stomatal opening. Extracellular application of 10 [mu]M ABA inhibited stomatal opening by 98% at pH 6.15 and by 57% at pH 8.0. The pH dependence of extracellular ABA action may suggest a contribution of an intracellular ABA receptor to stomatal regulation. The findings presented here show that intracellular ABA alone does not suffice to inhibit stomatal opening under the imposed conditions. Furthermore, these data provide evidence that a reception site for ABA-mediated inhibition of stomatal opening is on the extracellular side of the plasma membrane of guard cells.

Journal Article↗
PubMed1968

Effect of Infection by Hypomyces solani f. sp. Cucurbitac on Apparent Free Space, Cell Membrane Permeability, and Respiration of Squash Hypocotyls.

Initial symptoms and increases in respiration, apparent free space, and rate of leakage of amino acids occurred concomitantly in squash (Cucurbita maxima Dcne) hypocotyls infected by Hypomyces solani f. sp. cucurbitae Snyd. and Hans. Young, rapidly expanding lesions had greater respiratory rates and apparent free space than comparable tissues from healthy plants.Hypocotyl tissues above (1-45 mm) lesions possessed greater endogenous respiratory rates (2-3 times) and lower respiratory quotients than similar tissues from healthy plants. But no differences were found in membrane permeability to nonelectrolytes and water and in apparent free space between cells above lesions and healthy hypocotyls.Host cells contiguous to fungal hyphae at lesion margins were completely permeable to solutes and failed to accumulate neutral red or exhibit cyclosis.

Journal Article↗
PubMed1971

Specificity of deoxyribonucleic Acid intercalating compounds in the control of phenylalanine ammonia lyase and pisatin levels.

Compounds with planar triple ring systems such as acridine orange, 9-amino acridine, 9-amino-1,2,3,4-tetrahydroacridine (tacrine), 6,9-diamino-2-ethoxyacridine lactate monohydrate (DE-acridine), 6-chloro-9-(3'-diethylamino-2'-hydroxypropylamino) -2-methoxyacridine.2 HCl (CDM-acridine), quinacrine, 6-chloro-9-(4'-diethylamino-1'-methylbutylamino) -2-methoxy-1,10-diazaanthracene (CDM 1,10-diazaanthracene), thionine, azure A, methylene blue, and pyronine Y when applied to excised pea pods were potent inducers of phenylalanine ammonia lyase or of pisatin, or of both. Compounds with an array of structural variation around the planar three-ring system were tested for their ability to induce these responses in pea tissue. In general, dimethylamino, diethylamino, or amino substitutions at position 2 and 6 or an amino (with or without an aliphatic side chain) substitution at position 9 of the three-ring system augmented induction potential. Methyl green, methylene blue, 2,7-diaminofluorene, nile blue, neutral red, pyrogallol red, ethidium bromide, nogalamycin, quinine, chloroquine, spermine, 8-azaguanine, gliotoxin, chromomycin A(3), actinomycin D, and mitomycin C were also potent inducers. The inhibition of phenylalanine ammonia lyase induction by the application of actinomycin D (300 micrograms per milliliter) or 6-methylpurine (1 milligram per milliliter) within 1 hour after inducer application indicated that newly synthesized RNA is necessary for induction. Phenylalanine ammonia lyase induction was also inhibited by cycloheximide (150 micrograms per milliliter).

Journal Article↗
PubMed1978

Presence of the cyanogenic glucoside dhurrin in isolated vacuoles from sorghum.

Large numbers of vacuoles (10(6)-10(7)) have been isolated from Sorghum bicolor protoplasts and analyzed for the cyanogenic glucoside dhurrin. Leaves from light-grown seedlings were incubated for 4 hours in 1.5% cellulysin and 0.5% macerase to yield mesophyll protoplasts which then were recovered by centrifugation, quantitated by a hemocytometer, and assayed for cyanogenic glucosides. Mature vacuoles, released from the protoplasts by osmotic shock, were purified on a discontinuous Ficoll gradient and monitored for intactness by their ability to maintain a slightly acid interior while suspended in an alkaline buffer as indicated by neutral red stain. Cyanide analysis of the protoplasts and the vacuoles obtained there from yielded equivalent values of 11 mumoles of cyanogenic glucoside dhurrin per 10(7) protoplasts or 10(7) vacuoles. This work supports an earlier study from this laboratory which demonstrated that the vacuole is the site of accumulation of the cyanogenic glucoside in Sorghum.

Journal Article↗
PubMed1981

High-temperature Disruption of Guard Cells of Vicia faba: EFFECT ON STOMATAL APERTURE.

Increased variability in stomatal aperture at high temperatures can be attributed, in part, to the differential sensitivity of guard cells to thermal damage. Individual stomata become increasingly open at higher temperatures until guard cells are lethally damaged; at that temperature, apertures decrease. The extent of irreversible damage causing closure was estimated by K(+) uptake, neutral red accumulation, and visual scoring of chloroplasts.This study found that visual scoring of chloroplast disruption provided the best estimate of guard cell viability at high temperature. Removal of the damaged guard cells from the population sample resulted in a constant coefficient of variability for apertures over the temperature range 25 to 50 C.

Journal Article↗
PubMed1981

Uptake and Concentration of Alkylamines by a Marine Diatom: EFFECTS OF H AND K AND IMPLICATIONS FOR THE TRANSPORT AND ACCUMULATION OF WEAK BASES.

Methylamine, ethylamine, and dimethylamine (10 micromolar) are taken up and concentrated 600 to 6,000-fold by Cyclotella cryptica. Methylamine is concentrated most strongly, and its accumulation and retention are relatively insensitive to external pH but strongly inhibited by 30 millimolar external K(+). Accumulation and retention of ethyl- and dimethylamine, on the other hand, are strongly affected by external pH and less sensitive to external [K(+)]. Intracellular pH, as estimated from neutral red staining and quenching of 9-aminoacridine fluorescence, was between 4 and 5, with the central vacuole being the major acidic compartment. The accumulation of ethyl- and dimethylamine could result from diffusion of the uncharged amine across the membrane(s) and passive equilibration of the charged form (R-NH(3) (+)) inside and outside the cell. Differences in the accumulation ratio and the ion dependence for methylamine uptake relative to ethyl- and dimethylamine uptake suggests that a different mechanism is responsible for the concentration of the simpler amine.

Journal Article↗
PubMed1982

pH in Vacuoles Isolated from Castor Bean Endosperm.

Vacuoles were prepared from germinating castor bean endosperm (Ricinus communis var Hale) and purified by filtration through a cotton layer under physiological osmolarity. The purity of vacuoles prepared by this method was comparable with that prepared by a sucrose step gradient centrifugation reported in a previous paper (Nishimura, Beevers 1978 Plant Physiol 62: 44-48). It was shown by assays of marker enzymes that the final preparation contained trace contamination of other organelles (glyoxysomes, mitochondria, and endoplasmic reticulum) and the cytosol. The isolated vacuoles were stained with neutral red, indicating that the intravacuolar pH is acidic. Intravacuolar pH of isolated vacuoles was determined by measuring the distribution of [(14)C]methylamine in the vacuoles and by directly measuring the pH of vacuolar extracts. The pH of isolated vacuolar extracts was 5.7 to 5.9. Similar values were obtained by the methylamine method and it was shown that intravacuolar pH increased as the pH of the medium was increased.

Journal Article↗
PubMed1982

Evidence for compartmentalization of conjugates of 2,4-dichlorophenoxyacetic Acid in soybean callus tissue.

Soybean Glycine max L. Merrill var. Amsoy 71 root callus tissue labeled with [1-(14)C]2,4-dichlorophenoxyacetic acid (2,4-D) which was subsequently incubated for 24 hours in the absence of 2,4-D, released considerable amounts of label into the media. These results led to an examination of the efflux of 2,4-D and 2,4-D metabolites during a 6-hour time period. Fifty% of the free 2,4-D was lost in 15 minutes and 99% in 6 hours. After 6 hours, only about 48% of the ether-soluble fraction (mainly the glutamic and aspartic conjugates) and about 33% of the aqueous-soluble fraction (mainly hydroxylated glycosides) effluxed from the tissue. Neutral red efflux from stained callus tissue was enhanced only 5% above the control by treatment with 7.5% dimethylsulfoxide (DMSO) and 50% with 20% DMSO. Similar soybean callus tissue preincubated with [1-(14)C]2,4-D and subsequently incubated with H(2)O, 7.5% DMSO, and 20% DMSO was examined for efflux of (14)C label. DMSO similarly enhanced the efflux of the ether and aqueous soluble conjugates.DMSO concentrations of less than 10% did not damage the vacuolar membranes which also has been reported with cultured tobacco cells (Delmer 1979 Plant Physiol 64: 623-629). From these data, it seems that the 2,4-D metabolites are located in a compartment of the cell and presumably the vacuole.

Journal Article↗
PubMed1985

ADP Is a Competitive Inhibitor of ATP-Dependent H Transport in Microsomal Membranes from Zea mays L. Coleoptiles.

An anion-sensitive ATP-dependent H(+) transport in microsomal membranes from Zea mays L. coleoptiles was partially characterized using the pH gradient-dependent decrease of unprotonated neutral red. The following criteria strongly suggest a tonoplast origin of the H(+) transport observed: strict dependence on Cl(-); inhibition by SO(4) (2-) and NO(3) (-); insensitivity against vanadate, molybdate, and azide; reversible inhibition by CaCl(2) (H(+)/Ca(2+) antiport); inhibition by diethylstilbestrol. The substrate kinetics revealed simple Michaelis Menten kinetics for ATP in the presence of 1 millimolar MgCl(2) with a K(m) value of 0.56 millimolar (0.38 millimolar for MgATP). AMP and c-AMP did not influence H(+) transport significantly. However, ADP was a potent competitive inhibitor with a K(i) value of 0.18 millimolar. The same inhibition type was found for membranes prepared from primary roots by the same procedure.

Journal Article↗
PubMed1985

Analysis of Guard Cell Viability and Action in Senescing Leaves of Nicotiana glauca (Graham), Tree Tobacco.

In an attempt to determine whether low epidermal conductances to water vapor diffusion of senescing leaves were caused by internal changes in guard cells or by factors external to guard cells, stomatal behavior was examined in intact senescing and nonsenescing leaves of Nicotiana glauca (Graham), tree tobacco, grown in the field or in an environmental chamber. Conductances of senescing leaves were 5 to 10% of the maximum conductances of nonsenescing leaves of the same plant, yet guard cell duplexes isolated from epidermal peels of senescing leaves developed full turgor in the light in solutions containing KCl, and sodium cobaltinitrite staining showed that K(+) accumulated as turgor developed. Ninety-five per cent of the guard cells isolated from senescing leaves concentrated neutral red and excluded trypan blue. Intercellular leaf CO(2) concentrations of senescing and nonsenescing leaves of chamber-grown plants were not significantly different (about 240 microliters per liter), but the potassium contents of adaxial and abaxial epidermes of senescing leaves taken from plants grown in the field were less than half those of nonsenescing leaves. We conclude that guard cells do not undergo the orderly senescence process that characteristically takes place in mesophyll tissue during whole-leaf senescence and that the reduced conductances of senescing leaves are produced by factors external to guard cells.

Journal Article↗
PubMed1985

The Compartmentation of Abscisic Acid and beta-d-Glucopyranosyl Abscisate in Mesophyll Cells.

beta-d-Glucopyranosyl abscisate (ABA-GE) is synthesized in Xanthium strumarium L. leaves during water stress. Following recovery from stress, the amount of ABA-GE does not decline. These observations led to the hypothesis that ABA-GE is sequestered in the vacuole where it is metabolically inert. The localization of abscisic acid (ABA) and ABA-GE was investigated by a dimethyl sulfoxide (DMSO) compartmentation method and by direct isolation of vacuoles.With the DMSO compartmentation method it was shown that in Xanthium mesophyll cells ABA was in a compartment not accessible to DMSO, presumably the chloroplast, whereas ABA-GE was in a compartment accessible to DMSO, presumably the vacuole. Neutral red, which accumulates in the vacuoles, showed a similar DMSO concentration dependence for its release from the cells as ABA-GE.Vacuoles isolated from Vicia faba L. leaf protoplasts contained 22% of the total ABA and 91% of the ABA-GE. Some of the ABA in the vacuole preparations was probably due to cytoplasmic contamination. These findings indicate that ABA-GE is sequestered in the vacuoles of mesophyll cells where the conjugated form of ABA is removed from the active ABA pool.

Journal Article↗
PubMed1986

Association of H-Translocating ATPase in the Golgi Membrane System from Suspension-Cultured Cells of Sycamore (Acer pseudoplatanus L.).

The Golgi complex and the disrupted vesicular membranes were prepared from suspension-cultured cells of sycamore (Acer pseudoplatanus L.) using protoplasts as the starting material and employing linear sucrose density gradient centrifugation followed by osmolysis (Ali et al. [1985] Plant Cell Physiol 26: 1119-1133). The isolated Golgi fraction was found to be enriched with marker enzyme activities and depleted of the activity of a typical mitochondrial marker enzyme, cytochrome c oxidase. Golgi complex, and vesicular membranes derived thereof were found to contain the specific ATPase (specific activity of about 0.5 to 0.7 micromoles per minute per milligram protein). Inhibitor studies suggested that the ATPase of Golgi was different from plasma membrane, tonoplast and mitochondrial ATPases as it was not inhibited by sodium vanadate, potassium nitrate, oligomycin and sodium azide. The sensitivity to N-ethylmaleimide further distinguished the Golgi ATPase from F(0) to F(1) ATPase of mitochondria. The internal acidification was measured by monitoring the difference in absorbance at 550 nanometers minus 600 nanometers using neutral red as a probe. The maximum rate detected with Golgi and disrupted membrane system was 0.49 and 0.61 optical density unit per minute per milligram protein, at pH 7.5, respectively, indicating that the proton pump activity was tightly associated with the Golgi membranes. In both cases, the acidification was inhibited 70 to 90% by various ionophores, indicating that the proton pump was electrogenic in nature. Both the Golgi ATPase activity and ATP-dependent acidification were profoundly inhibited by N,N'-dicyclohexylcarbodiimide, which also indicate that the two activities are catalyzed by the same enzyme.

Journal Article↗
PubMed1988

Anion-Sensitive Mg ATP-Dependent Proton Pumping in Microsomal Membranes from Phycomyces blakesleeanus Bgff.

A light microsomal membrane fraction (collected on 28% weight/volume sucrose) from young mycelia of Phycomyces blakesleeanus Bgff. stationary cultures exhibited Mg(2+) ATP-dependent proton pumping as monitored with the dye neutral red or by accumulation of [(14)C]methylamine. The substrate kinetics for ATP (K(m(ATP)) 1.1 millimolar in the presence of 2 millimolar Mg(2+)), the competitive inhibition by ADP (K(i(ADP)) 0.8 millimolar), the anion sensitivity (stimulation by Cl(-), inhibition by NO(3) (-) and SO(4) (2-)), the reversal of acidification by Ca(2+), the inhibition by diethylstilbestrol and dicyclohexylcarbodiimide, as well as the absence of any inhibition by azide, molybdate, and vanadate strongly suggest a tonoplast-type ATPase driven proton pumping. The same membrane fraction showed no pyrophosphate driven H(+)-translocation. Electron microscopic examination of the fungal mycelium demonstrated the presence of vacuoles of different sizes and other nonidentified vesicles but no typical Golgi stacks.

Journal Article↗
PubMed1989

Isolation of Guard Cell Protoplasts from Mechanically Prepared Epidermis of Vicia faba Leaves.

A method for isolating guard cell protoplasts (GCP) from mechanically prepared epidermis of Vicia faba is described. Epidermis was prepared by homogenizing leaves in a Waring blender in a solution of 10% Ficoll, 5 millimolar CaCl(2), and 0.1% polyvinylpyrrolidone 40 (PVP). Attached mesophyll and epidermal cells were removed by shaking epidermis in a solution of Cellulysin, mannitol, CaCl(2), PVP, and pepstatin A. Cleaned epidermis was transferred to a solution of mannitol, CaCl(2), PVP, pepstatin A, cellulase "Onozuka" RS, and pectolyase Y-23 for the isolation of GCP. Preparations made by this method included both adaxial and abaxial GCP and contained </=0.017% mesophyll protoplasts, </=0.6% mesophyll fragments, and no epidermal cell contaminants. Yields averaged 9 x 10(4) protoplasts/leaflet and 98 to 100% of the GCP excluded trypan blue, concentrated neutral red, and hydrolyzed fluorescein diacetate. Isolated GCP increased in diameter by 2.2 micrometers after incubation in darkness in 10 micromolar fusicoccin, 0.4 molar mannitol, 5 millimolar KCl, and 1 millimolar CaCl(2). Illumination of GCP with 800 micromoles per square meter per second of red light resulted in alkalinization of their suspension medium. When 10 micromolar per square meter per second of blue light was superimposed onto the red light background, the medium acidified. Measurements of chlorophyll a fast fluorescence transients from isolated GCP indicated that GCP were capable of electron transport, and slow transients contained the "M" peak usually associated with a functional photosynthetic carbon reduction pathway.

Journal Article↗
PubMed1991

Elevated thymidine phosphorylase activity in psoriatic lesions accounts for the apparent presence of an epidermal "growth inhibitor," but is not in itself growth inhibitory.

An apparent tissue-specific growth inhibitor, or chalone, obtained from psoriatic lesions was tentatively identified in the 100-kDa fraction based upon inhibition of DNA synthesis, as measured by [3H]-thymidine uptake by a squamous cell carcinoma cell line, SCC 38. This fraction, however, failed to inhibit SCC 38 cell growth when assessed directly in a neutral red uptake assay. Characterization of the inhibitor of [3H]-thymidine uptake revealed it to have biochemical properties identical to thymidine phosphorylase: 1) molecular weight close to 100 kDa, 2) isoelectric point of 4.2, and 3) thymidine phosphorylase enzyme activity. Thus, we conclude that its ability to inhibit [3H]-thymidine uptake was due to thymidine catabolism rather than inhibition of DNA synthesis or growth inhibition. Examination of thymidine phosphorylase activity in keratome biopsies from psoriatic and normal skin demonstrated a twentyfold increase in activity in psoriatic lesions relative to non-lesional or normal skin. This increase in metabolism of thymidine was due to thymidine phosphorylase rather than uridine phosphorylase activity. The correlation between increased thymidine phosphorylase activity and increased keratinocyte proliferation in vitro (cultured) and in vivo (psoriasis), suggests that this enzyme may play a critical role in providing the thymidine necessary for keratinocyte proliferation.

Biopsy↗
PubMed2004

Comparative effectiveness of hand and ultrasonic instrumentations in root surface planing in vitro.

BACKGROUND/AIMS: A variety of techniques are employed for planing and scaling of the superficial root surfaces, of which hand and ultrasonic instrumentations have been preferentially used in routine periodontics clinics. This study was undertaken to compare the effectiveness of ultrasonic scalers and hand curettes in facilitating fibroblast attachment to the scaled root surfaces. MATERIALS AND METHODS: Sixteen patients with periodontally involved teeth and nine subjects without periodontal diseases (control subjects) were selected. Two single-rooted teeth were extracted from each subject. Mesial and distal surfaces of teeth were selected in treated and untreated groups, respectively. The mesial surface of each tooth was randomly chosen to be treated either by hand curettes or ultrasonic instrumentation. The degree of cell attachment on the root surfaces of treated and untreated groups from control subjects and patients was then determined by the use of a gingival fibroblast line established and employed at early passages. The attachment and proliferation of gingival fibroblasts on the root surfaces were evaluated using neutral red assay and scanning electron microscopy (SEM). RESULTS: Fibroblast survival and proliferation on the surfaces of untreated periodontally involved roots were found to be significantly lower compared with control untreated surfaces (p<0.0001) or treated surfaces from patients (p<0.0001). No significant difference, however, was observed between root surfaces treated either by hand curettes or ultrasonic scalers. CONCLUSION: These results indicate the beneficial effectiveness of both techniques in root treatment and planing.

Adult↗