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Results for “Neutral Red”

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PubMed1990

A specific fluorescent dye for ex situ staining of vital islets of Langerhans: neutral red.

We present a new technique for specific ex situ fluorescent staining of islets of Langerhans with neutral red. Depending on the concentration of neutral red (1 microgram/ml), this technique allows the differentiation between exocrine and endocrine pancreatic tissue, according to differences in fluorescence intensity. Pancreatic islets can be stained not only in situ, but in particular ex situ after pancreas digestion. Since intravital staining of the pancreas in situ with neutral red is not applicable in human transplantation, the staining procedure ex situ may be a useful tool for islet purification by particle sorting, using a fluorescent-light-activated system; thus, a sufficient mass of purified islets for free transplantation may be isolated.

Animals↗
PubMed1992

Histochemical probing of potato periderm with neutral red: a sensitive cytofluorochrome for the hydrophobic domain of suberin.

A technique is described which uses the lipid fluorochrome neutral red as a cytochemical probe to detect the hydrophobic domain of the ligno-suberin matrix in native and wound periderm of potato tuber. Toluidine blue O is used as a counterstain to quench autofluorescence. The neutral red technique appears to be specific for the hydrophobic/lipid domain of suberin and is significantly more sensitive than Sudan III and IV. The fluorochrome was extensively used on paraffin-embedded tissue with excellent results but also worked on freehand sections of fresh periderm tissue. In tuber tissue undergoing wound-healing, the pattern of suberin fluorescence obtained with the neutral red probe was identical in specificity to the color pattern obtained with Sudan III/IV, but somewhat different than that observed when berberine was used. Results obtained with the neutral red probe and berberine probe visually demonstrated that during ligno-suberin biosynthesis, the depositions of hydrophobic/lipid and phenolic/lignin-like components in potato tuber periderm were separate processes. The deposition of these components does not necessarily require their simultaneous presence because the fluorescence from these probes showed that the components were not consistently present together on the cell walls.

Berberine↗
PubMedDate not supplied

Neutral red fluorescence of chromatin: specificity and binding mechanism.

After treatment with neutral red at low concentrations (10(-6), 10(-5) M), the chromatin of chicken erythrocytes shows an intensive red fluorescence, which is reduced or practically abolished when nuclei become stained by using the dye at concentrations higher than 10(-4) M. Both the fluorescence and staining reactions are dependent on the DNA content of chromatin. Neutral red fluorescence of nuclei increases considerably after treatment with inorganic cations (Al3+, Ba2+), while previous treatments with methylene blue reduce the fluorescence intensity. The possibility that chromatin fluorescence depends on the intercalative binding of neutral red is suggested.

Animals↗
PubMed1984

Subcellular localization of neutral red staining in Limulus ventral photoreceptors.

Limulus ventral photoreceptors are vitally stained by neutral red. In other systems such staining has been correlated with the presence of monoamines or neuropeptides. The stained cellular components in ventral photoreceptors are clusters of small ovoids which have been identified as residual bodies. These structures are unlikely candidates for monoamine or neuropeptide synthesis or storage sites, but may be part of the cyclic synthesis and degradation of photosensitive membrane. While vital staining with neutral red is a particularly useful method for identifying certain classes of neurons in vivo, in the case of ventral photoreceptors, the association of the vital staining property with the presence of a particular class of neurotransmitter candidates has proven difficult. Neutral red is useful, however, for visualizing the segmentation of ventral photoreceptors in vivo.

Animals↗
PubMedDate not supplied

Neutral red assay in minimum fungicidal concentrations of antifungal agents.

We assayed the fungicidal effects of antifungal agents using neutral red staining. Fungal elements of Trichophyton mentagrophytes and T. rubrum were treated with various concentrations of antifungal agents in 96-well filtration plates and then stained with neutral red. The amount of neutral red incorporated by the surviving viable cells was determined from the automated spectrophotometric readings at 550 nm. The minimum fungicidal concentrations (MFCs) of antifungal agents determined by this assay correlated well with those determined by conventional assay. This newly developed procedure should provide a rapid, reproducible, quantitative, qualitative and semi-automated susceptibility test for determination of the MFCs of the fungicidal agents.

Antifungal Agents↗
PubMed1975

Enhancement of human interferon production by neutral red and chloroquine: analysis of inhibition of protein degradation and macromolecular synthesis.

Two lysosomotrophic drugs, neutral red and chloroquine, enhance polyinosinic:polycytidylic acid-induced interferon production by a strain of diploid human fibroblasts (FS-4). Treatment of cells with neutral red or chloroquine between 2.5 and 3.5 h after induction increases interferon yields 16- to 64- and 4- to 16-fold, respectively, in the subsequent 20.5 h. The two drugs inhibit the rates of protein degradation and of RNA and protein synthesis. In addition, neutral red is a very potent inhibitor of uridine transport into cells. Normalized dose-effect curves show that interferon superinduction is correlated with the inhibition of macromolecular synthesis, but not with that of protein degradation. Treatment of cells with chloroquine at low concentration (25 mug/ml) for a prolonged period of time (24 h) caused approximately 40% reduction in the rate of protein degradation. The usual rapid shutoff of interferon production and the effectiveness of effectiveness of actinomycin D superinduction are not altered by this treatment. This strongly suggests that inhibition of intralysosomal protein degradation does not significantly contribute to interferon superinduction. Degradation of the rapidly and the slowly turning over proteins was unaffected by actinomycin D under conditions of treatment known to enhance interferon production. Treatment with cycloheximide (5 or 50 mug/ml for 5 h) inhibited the rate of degradation of the rapidly turning over component by 10% and the slow component by 30-40%, which suggests that the two components turn over by distinct cellular mechanisms.

Cells, Cultured↗
PubMed1985

[Functional evaluation of cultured cells under hypotonic conditions by intravital staining with neutral red].

A high stability of pig embryo kidney-cells to hypotony was shown with neutral red vital staining. In the medium, diluted 1 : 1, the cells kept their ability to make granules during 6 days. In the medium diluted by water 1 : 3, both granular and diffuse staining of cells was shown within 6-12 hours. Later (18-48 hours) the cell ability to make granules was kept, but the neutral red was deposed as large vacuoles. In the normal medium the cell ability to make granules was kept too. In the medium, diluted by water 1 : 7, the cells lost their ability to make granules. The ability was recovered when cells were returned to the normal medium. Thus, after 6-18 hours of incubation in such a hypotonic medium, the cells produced small granules of neutral red, and 24-48 hours later they made large granules.

Animals↗
PubMedDate not supplied

The neutral red release assay: a review.

The neutral red release (NRR) assay is a cytotoxicity test that can be used to measure the immediate toxic effects of test substances on the cell membrane, resulting in the leaking of intracellular contents. The assay has already been used for several years to evaluate the cytotoxicities of various kinds of products, such as cosmetics, pharmaceuticals, industrial chemicals and household products. It has undergone in-house validation by many companies, and has been found to be particularly useful for identifying substances that are potentially capable of causing adverse reactions on coming into brief contact with the eye or the skin at relatively high concentrations, such as might occur in an adventitious splash into the eye or onto the skin, followed by a quick rinse. Because of the relatively long existence of the NRR assay, its practicality and its proven usefulness for particular purposes, ECVAM decided to review the status of the method, in order to decide whether prevalidation and formal validation studies on the test might be profitable. The review of the status of the test was carried out by performing a comprehensive review of the literature, and by conducting a survey involving companies and institutes with experience in using the test. Both the review and the survey revealed that the assay could provide extremely valuable information when it was used for particular purposes, such as for the evaluation and comparison of immediate toxic effects on the eye or the skin caused by certain products or chemicals such as surfactants. Most of those who responded in the survey favoured a prevalidation/validation study.

Animal Testing Alternatives↗
PubMed1995

Flow cytometric assay of phagocytic activity of human neutrophils and monocytes in whole blood by neutral red uptake.

In a new, simple, and fast flow-cytometric method for the simultaneous measurement of phagocytic activity of human neutrophils and monocytes in whole blood, the fluorescence capability of the well-known vital stain, neutral red was used. The incubation of 0.5 ml heparinized human blood with the phagocytic stimulus of zymosan dose- and time-dependently increased the percentage and the red fluorescence intensity of both neutrophils (4.3 +/- 1.2 times) and monocytes (2.7 +/- 0.7 times) measured cytofluorimetrically. Decreased uptake of neutral red was observed in a patient with phagocytic disorder, based upon impaired engulfment of particles and production of reactive oxygen species. In a patient with chronic granulomatosis, however, no decrease of neutral red uptake was measured. Platelet activating factor and phorbol myristate acetate were also able to increase the uptake of neutral red by both monocytes and neutrophils, but to a lesser extent than zymosan. The advantage of this method is the possibility for the simultaneous measurement of phagocytic activities of monocytes and neutrophils stimulated by either particles or soluble activators. This method is suitable for the selective measurement of activation processes not related to the production of free radicals in the phagocytes.

Adolescent↗
PubMed1975

Neutral red with photoinactivation in the treatment of herpes genitalis.

A clinical trial was undertaken to compare the efficacy of neutral red photodynamic inactivation treatment of genital herpes infections with that of a non-photoactive dye, phenol red, as a control. In a series of nineteen patients with virologically proven herpes genitalis who were adequately followed, eleven were treated with neutral red, and eight with phenol red; no difference in response to therapy was found between the two groups, and it is concluded that under the conditions of this trial neutral red with photoinactivation was not effective in the treatment of acute genital herpes infections. Approximately 75 per cent. of those with vulval lesions also had concurrent cervical infection, so that an effective topical treatment would need to be applicable to both anatomical sites.

Antibodies, Viral↗
PubMed1975

Dermatitis from neutral red therapy of herpes genitalis.

A case of contact dermatitis from neutral red dye applied for treatment of herpes genitalis is presented. A review of the literature revealed 5 other patients with a similar reaction. We suggest that neutral red dye treatment for herpes should be used with caution in patients with an allergic history.

Administration, Topical↗
PubMed2001

Uridine uptake inhibition as a cytotoxicity test for a human hepatoma cell line (HepG2 cells): comparison with the neutral red assay.

This study describes a sensitive microassay for measuring cytotoxicity based on the degree of inhibition of RNA synthesis in HepG2 cells. RNA synthesis is measured by the kinetic uptake of radiolabeled uridine. A large number of compounds were tested in a wide range of concentrations. The concentration required to induce 50% inhibition of HepG2 uridine uptake rates (IC(50)) was determined for each compound and used to rank its potency. These IC(50)s were compared with IC(50)s measured with the neutral red assay. 2-acetylaminofluorene, benzo[a]pyrene and methylnitrosourea were not cytotoxic in the neutral red assay. Uridine uptake was always inhibited at lower concentrations than those required in the neutral red assay, suggesting that the uridine uptake assay is a more sensitive indicator of toxic action than the neutral red inclusion. Uridine uptake assay provides a rapid and quantitative method for assessing toxicity in a human cell line. Application of this method to bottled spring waters are described. Due to its high sensitivity and reproducibility, this method provides a suitable tool for screening a great number of samples and will be a helpful test for evaluating food safety and controlling the recycling process of wrapping materials.

2-Acetylaminofluorene↗
PubMed1990

A semi-automated neutral red based chemosensitivity assay for drug screening.

A semi-automated colorimetric chemosensitivity assay was developed. The assay utilizes the vital stain neutral red for the rapid screening of potential anticancer agents using solid tumor cell lines. The cell lines used in this assay and presented in this report are CX-1 colon adenocarcinoma and A549 lung carcinoma. The assay, performed in 96 well tissue culture plates, allows for short drug exposure times (3 hrs.) followed by quantitation of cell number (neutral red absorbance) following four cell doubling times. Cell number directly correlated with absorbance of eluted neutral red at 540 nm. However, optimal amounts of dye and staining times varied between cell lines. IC50 concentrations (for inhibition of cell growth) determined using this assay were in good agreement with results from clonogenic assays using similar drug treatment conditions. The assay technique was determined to be capable of detecting antineoplastic compounds operating by a wide variety of mechanisms.

Adenocarcinoma↗
PubMed1993

Comparison of the neutral red and methylene blue assays to study cell growth in culture.

The neutral red and methylene blue in vitro cytotoxicity assays were compared under a variety of conditions using normal human ovarian epithelial cells to determine whether either assay is superior for studying cell growth. The results were standardized against a DNA spectrofluorometric assay. Although the assays were equivalent in reflecting cell number, each has specific advantages: while neutral red discriminates between viable and dead cells, the methylene blue assay is more sensitive and easier to perform.

Cell Division↗
PubMed1993

[Labeling of yeast protoplasts by neutral red and nile blue for fusion experiments].

Neutral red and Nile blue were found to be suitable for staining protoplasts from various strains of Saccharomyces cerevisiae. The absorption of stains by the protoplasts was dependent on the pH value, for both stains. At a pH of 7.9 the protoplasts of the fusion partners could be stained differently and therefore it was possible to observe the fusion between the various strains of yeast. Consequently the prerequisites were created for the following micromanipulation.

Fluorescent Dyes↗
PubMed1997

KTP laser and neutral red phototherapy of human squamous cell carcinoma.

Neutral red (NR) is a cationic, nontoxic vital dye employed as a histologic stain for proliferating cells; it has been used clinically for photodynamic treatment of herpes simplex virus lesions. NR is selectively taken up and concentrated by mitotic cells, an important characteristic for more effective antineoplastic agents. In the present study, UCLA-SO-P3 human squamous carcinoma cells displayed minimal toxicity when incubated with up to 50 microg/ml NR in the absence of light. However, cells incubated with greater than 0.5 microg/ml NR followed by exposure to KTP laser light at 532 nm exhibited nearly 100% tumor cell death. The degree of cell toxicity was proportional to NR dose and laser light fluence. This study demonstrates that NR is an excellent cancer cell photosensitizer in vitro, and, after adding additional in vivo preclinical testing, may prove to be a useful agent in photodynamic destruction of head and neck tumors.

Antineoplastic Agents↗
PubMed2005

In vitro cytotoxicity assays: comparison of LDH, neutral red, MTT and protein assay in hepatoma cell lines following exposure to cadmium chloride.

The aim of this study was to compare four in vitro cytotoxicity assays and determine their ability to detect early cytotoxic events. Two hepatoma cell lines, namely HTC and HepG2 cells, were exposed to cadmium chloride (0-300 microM) for 3, 5 and 8 h. Following exposure to the toxic metal cytotoxicity was determined with the lactate dehydrogenase leakage assay (LDH), a protein assay, the neutral red assay and the methyl tetrazolium (MTT) assay. In HTC cells no toxicity was observed for any incubation period when the LDH leakage, the MTT and the protein assay were employed whereas the neutral red assay revealed early cytotoxicity starting after incubation of HTC cells with CdCl(2) for 3 h. In the case of HepG2 cells the MTT assay reveals cytotoxicity due to CdCl(2) exposure after 3 h whereas no such effect is seen with the other three assays. Following 5 h exposure of HepG2 cells to CdCl(2), toxicity is observed with the MTT assay at lower concentrations compared to the ones required for detection of toxicity with the LDH leakage and the neutral red assay. In conclusion different sensitivity was observed for each assay with the neutral red and the MTT assay being the most sensitive in detecting cytotoxic events compared to the LDH leakage and the protein assay.

Animals↗