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At least 649 records · Page 36Linked to original sources
PubMed2000

Blastocystis hominis: origin and significance of vacuolar and granular forms.

Using supravital neutral red staining and light microscopy, individual Blastocystis organisms, subcultured from clinical isolates in modified monophasic Robinson's medium, were followed over various periods on glass slides. A rapid transition from uniformly stained to granular and vacuolated forms preceded the organism's death as evidenced by pale staining and Brownian motion in the cell's interior. Granular and vacuolar forms of Blastocystis may indicate degenerative changes in individual cells, fixation artifact, or both.

Animals↗
PubMed1979

A cinematographical study of the development of vitally stained Dictyostelium discoideum.

We report observations from time-lapse films of the development of Dictyostelium discoideum (Dd) stained with the vital dye neutral red. We have used this dye to enable us to track individual cells, as they move through multicellular tissues in later Dd stages. Our observations lead us to new conclusions about the control of cell movement and cell contact during Dd development, including the tentative conclusion that the aggregation control competences regulate cell behaviour throughout the whole of Dd. development. We are led to specific hypotheses for the mechanisms of later morphogenetic movements and pattern formation.

Dictyostelium↗
PubMed1976

[Method for the intavital of the isolated pancreatic islands of Langerhans in rats].

The authors describe a method of vital detection and isolation of individual islands of Langerhans in rats. This method is based on the capacity of the beta-cells of the islands to accumulate the stain during life. Since the stain (0.05% neutral red solution) is harmless and it is rapidly eliminated by the cells this method permits vital marking on the surface of the pancreas of individual islands and their distinguishment under steroscopic microscope; these islands can be isolated from the surrounding parenchyma of the pancreas with the aid of a microknife. Thus obtained islands of the pancreas could be used as material for experiments with implantation and for other experimental studies.

Animals↗
PubMed2000

Arachidonic acid release and prostaglandin E2 synthesis as irritant index of surfactants in 3T6 fibroblast cultures.

Surface-active agents are components of many drugs and cosmetics. [3H]arachidonic acid ([3H]AA) is rapidly incorporated into cell membrane phospholipids. As a result of membrane disintegration or enzymatic catalysis, it is released to the medium and [3H]AA metabolites can be measured by the scintillation technique. In order to validate the use of this test to predict the irritant and toxic effects of surfactants in vitro, various surfactants were examined using this methodology and the neutral red test. Benzalkonium chloride and sodium dodecylsulfate were more irritant and cytotoxic than amphoteric and non-ionic surfactants such as cocoamidopropylbetaine and Tween 80, respectively. The rank order of the toxicity/irritancy of these agents was similar to that given by other tests in vivo and in vitro. Moreover, our results confirm that the measurement of [3H]AA release in 3T6 fibroblast cultures is a sensitive assay of membrane damage.

Animals↗
PubMed1976

Transformation of human embryonic fibroblasts by photodynamically inactivated herpes simplex virus, type 2 at supra-optimal temperature.

Infection of human embryonic fibroblast cell monolayers with neutral red and light-inactivated herpes simplex virus, type 2 (HSV-2) at supra-optimal temperature (42 degrees C) resulted in persistence of viable cells in suspension culture at 37 degrees C which have properties in common with virus transformed cells: formation of cell aggregates, HSV-2-specific antigens and colony formation in soft methyl cellulose medium. These data are consistent with the idea that photodynamic inactivated HSV-2 has potential oncogenic activity.

Antigens, Viral↗
PubMed1992

Intracellular pH in rat brain in vivo and in brain slices.

Intracellular pH can be measured quantitatively in rat brain in vivo and in vitro using spectrophotometric detection of the vital dye neutral red. This method preserves spatial information and is compatible with microhistochemistry. The intracellular pH indicated by this method is in close agreement with that indicated by 31P-NMR spectroscopy. During ischemia, intracellular acidification is correlated with tissue lactate accumulation. The spatial distribution of pH values becomes more heterogeneous as the tissue becomes more acidic. Resuscitation from total cerebral ischemia produced by cardiac arrest results in rapid intracellular realkalinization. This realkalinization is at least partially inhibited by amiloride pretreatment. Some neuronal populations, especially in the hippocampal CA1 and CA4 regions, may become more acidic during ischemia and realkalinize more slowly after reperfusion than other tissue regions. The intracellular pH of hippocampal brain slice preparations is more alkaline than expected from in vivo studies. The intracellular pH of the brain slice can be acidified to near neutrality by specific inhibitors of the sodium/hydrogen ion exchanger.

Amiloride↗
PubMed2003

An in vitro study of biological safety of condoms and their additives.

The use of condoms to prevent sexually transmitted diseases, especially HIV, is widely encouraged. Condoms contain latex, nonspermicidal lubricants (such as dimethylsiliconium) and other nonspecified compounds, such as colorants and flavorings. Latex causes allergy reaction in susceptible individuals but little is known regarding the cytotoxic effects of other additives. The objective of this study was to develop a sensitive in vitro system to determine the toxic effects of condom material. The modified L929 FDA method and a more specific cell type, such as the cervical epithelial tumor cell line HeLa, was used. Lubricated (LC), lubricated and flavored (LFC), and lubricated, flavored and colored condoms (LFCC) were evaluated. Washings containing condom surface material were prepared by washing condom fragments in medium for different time intervals. Changes in cell number, viability and lysosome integrity in the L929 and HeLa cell lines was determined using the Crystal Violet, MTT and Neutral Red assays, respectively. The condom type affected cell viability and lysosome integrity, with LC inducing an increase in cell viability and LFC a decrease in lysosome integrity. The HeLa cell line in combination with the MTT and NR assay was themost sensitive in vitro system to determine the toxic effects of condom material.

Animals↗
PubMed1994

Molecular entrapment of small molecules within the interior of horse spleen ferritin.

A procedure for trapping small molecules inside the interior of horse spleen ferritin (HoSF) and methods for characterizing HoSF and its small entrapped molecules are described. HoSF is first dissociated into subunits by adjustment to pH 2 in the presence of the small molecules to be trapped. The pH of the dissociated HoSF is then increased to 7 at which time the dissociated subunits reassemble reforming the 24-mer HoSF, thereby trapping solvent within its interior. HoSF is then separated from unbound molecules by dialysis, ultrafiltration, and/or ammonium sulfate precipitation. Sephadex G-25 and DEAE chromatographic methods were also used to separate HoSF from unbound small molecules. Capillary electrophoresis (CE) was used to demonstrate the association of small molecules with HoSF after the pH-induced unfolding-refolding process. The pH indicator neutral red was clearly associated with HoSF and presumed trapped within the ferritin interior. Acid/base titrations suggested that the trapped indicator had a different pKa than the free indicator, a result which indicates that the ferritin interior is different than the external solution. The utility of using trapped molecules for gaining information on ferritin function is proposed and discussed.

Ammonium Sulfate↗
PubMed2006

Electrochemical studies on horseradish peroxidase covalently coupled with redox dyes.

The present study aims at investigating the use of redox dyes as non-diffusional electron mediators in hydrogen peroxide biosensors using horseradish peroxidase (HRP). We observe that the two redox dyes Safranine O and Neutral Red covalently bound to HRP, efficiently mediate electron transfer from the active site of the enzyme to the electrode surface. Dyes bound to the enzyme using a spacer arm diaminohexane further enhance the electron transfer. The enzyme electrodes show a linear response to the concentration of H2O2 up to 500 microM concentration and with a detection limit of around 50 microM. The dyes can be used as coupled mediators to develop a successful electro-optical biosensor.

Biosensing Techniques↗
PubMed2004

Biocompatibility of platinum-metallized silicone rubber: in vivo and in vitro evaluation.

Silicone rubber is commonly used for biomedical applications, including implanted cuff electrodes for both recording and stimulation of peripheral nerves. This study was undertaken to evaluate the consequences of a new platinum metallization method on the biocompatibility of silicone rubber cuff electrodes. This method was introduced in order to allow the manufacture of spiral nerve cuff electrodes with a large number of contacts. The metallization process, implying silicone coating with poly(methyl methacrylate) (PMMA), its activation by an excimer laser and subsequent electroless metal deposition, led to a new surface microtexture. The neutral red cytotoxicity assay procedure was first applied in vitro on BALB/c 3T3 fibroblasts in order to analyze the cellular response elicited by the studied material. An in vivo assay was then performed to investigate the tissue reaction after chronic subcutaneous implantation of the metallized material. Results demonstrate that silicone rubber biocompatibility is not altered by the new platinum metallization method.

Animals↗
PubMedDate not supplied

[Osmotic tolerance and adaptation to hypotonic medium of Echinorhynchus gadi (Acanthocephala, Echinorhynchidae)].

Minimum of the osmotic pressure in the intestine of the cod corresponds to the osmotic pressure of sea water of 10%. The sorbtion level of neutral red by intact E. gadi remained practically unchanged after their maintenance in sea water of 8-10 to 30% during 24 hours (ecological optimum). Specimens of E. gadi transferred from 10 to 4% displayed compensatory recovery of the normal sorbtion level of the dye by the 5th-6th day of the experiment. The ability of Acanthocephala possessing extreme eutelia to a physiological adaptation is indicative of its not obligatory participation of mitotic processes in the acclimation.

Absorption↗
PubMed2003

Cytotoxicity of a new endodontic filling material.

In vitro cell cultures have been widely used as a means of evaluating cytotoxicity of root canal filling materials. Following ANSI/ADA spec. no. 41, the aim of the present study was to investigate the biological compatibility of a new sealer (FibreFill) and compare it with some commercially available endodontic sealers (Bioseal and Acroseal). Mouse 3T3 fibroblasts were seeded and cultured and subsequently extracts of the cements were added. After 24 hours incubation, the cellular vitality of fibroblasts was evaluated by the neutral red uptake test (NRU), which measures the membrane permeability. Data were collected and statistically analysed. Results showed that all tested materials exhibited mild cytotoxic effects, which are compatible with normal clinical use, and no statistically significant difference was noted between FibreFill and the other tested materials. Therefore, selection amongst these sealers should be based on other factors.

3T3 Cells↗
PubMed2002

In vitro toxicity of stimulant soft drinks.

Some drinks containing natural products with stimulant properties are highly consumed among young adults. The market for these drinks has increased in past years around the globe, and, although they might be harmless, overdoses or combination of these with other drinks could be harmful to the health of some consumers in certain circumstances. Samples were obtained at food shops and different popular brands were chosen. Cytotoxicity tests used were neutral red uptake, total protein content, and tetrazolium assay on Chinese hamster ovary cells. Results revealed that tested samples were not cytotoxic; however, studies have demonstrated the toxicity of high concentrations of some of these products. For this reason, the authors considered it to be of critical importance to carryout an in vitro toxicity screening of stimulant soft drinks that are highly consumed.

Animals↗
PubMed2004

Acetylcholinesterase inhibition as a biomarker of adverse effect. A study of Mytilus edulis exposed to the priority pollutant chlorfenvinphos.

The inhibition of acetylcholinesterase (AChE) activity has been used widely as a biomarker of exposure to organophosphorous pesticides (OPs). However, scientific uncertainty about the risk assessment implications of data describing inhibition of cholinesterases in diverse species and tissues has hampered the use of AChE activity as a biomarker of adverse effect. Here, haemolymph AChE activity was combined with biomarkers of cellular integrity, immunotoxicity and physiological status in order to measure exposure to and the effects of the priority pollutant chlorfenvinphos. Laboratory exposures of the blue mussel Mytilus edulis to commercial grade chlorfenvinphos (Sapecron) were conducted over 24, 48 and 96 h. AChE activity in haemolymph of M. edulis was highly variable and bore no relationship to either sublethal effects or lethality over the range 0.003-0.03 mg/l chlorfenvinphos. In comparison, concentration dependent inhibition was evident for each of the remaining biomarkers (phagocytic activity, spontaneous cytotoxicity, neutral red retention time, total haemolymph protein). Mussels at the highest exposure concentration showed visual signs of neurotoxicity (impaired neuromuscular control). Haemocyte phagocytic activity and spontaneous cytotoxicity responses were highly sensitive to chlorfenvinphos with significant modulation evident after 24 h exposure to environmentally realistic concentrations of 0.007 mg/l (P = 0.0003). Thus the immune function and well being of the mussels was significantly impacted in the absence of measurable inhibition of haemolymph AChE.

Acetylcholinesterase↗
PubMedDate not supplied

In vitro phototoxicity testing: development and validation of a new concentration response analysis software and biostatistical analyses related to the use of various prediction models.

As demonstrated in several validation studies, the dermal phototoxic potential of chemicals in humans can be effectively assessed by in vitro methods. The core of these methods is to monitor dose-response curves of a chemical in the absence and presence of light, to quantify the difference between these two curves by appropriate measures (either the photo-irritancy factor [PIF], or the mean photo effect [MPE]), and to use these measures as predictors of in vivo phototoxicity. We present new concentration-response analysis software for in vitro phototoxicity testing, which runs on current personal computers, and takes into account all the limitations identified when using a former program. We also demonstrate the validity and robustness of this new software by applying it retrospectively to all data available from two phases of the EU/COLIPA validation trial for the 3T3 neutral red update in vitro phototoxicity test. Some frequently raised questions pertaining to the use of prediction models in phototoxicity testing are addressed, including: the necessity of using prediction models based on a cut-off; whether it is justifiable to use sharp prediction cut-off values; whether there is a biostatistical justification for the highest concentration of the test chemical; and whether repeated testing of a chemical is required.

3T3 Cells↗
PubMed1996

Immunomodulative effects of aflatoxins and selenium on human peripheral blood lymphocytes.

We investigated the antagonist immunomodulative properties of aflatoxin B1 and selenium on human peripheral blood lymphocytes by 2 colorimetric in vitro cytotoxicity assays, the neutral red uptake and the thiazolyl blue tetrazolium bromide assay. Immunotoxic properties of these substances were determined by a (3H)-thymidine DNA incorporation assay on phytohemagglutinin (PHA) stimulated and non-stimulated lymphocytes. Aflatoxin B1 and selenium, when studied separately, had an immunosuppressive effect on PHA stimulated and non-stimulated human peripheral blood lymphocytes. When they were studied together, they had an antagonistic effect on this immunological parameter.

Adjuvants, Immunologic↗
PubMed1987

Polycyclic aromatic hydrocarbon in vitro cytotoxicity to bluegill BF-2 cells: mediation by S-9 microsomal fraction and temperature.

The in vitro cytotoxicities of various polycyclic aromatic hydrocarbons (PAHs) to bluegill sunfish BF-2 cells were determined with the neutral red assay, which was modified by the incorporation of an S-9 microsomal fraction. Whereas the PAHs per se were weakly cytotoxic, the presence of the S-9 fraction in the incubation mixture increased the cytotoxicity of many of the PAHs, presumably due to the formation of active metabolites. In addition, the cytotoxicity of the PAHs (whether in the absence or presence of the S-9 microsomal fraction) was potentiated if the 6 h exposure was at 37, rather than at 26 degrees C.

Animals↗
PubMed2005

Removal of cationic dyes from aqueous solution by adsorption on peanut hull.

The potential feasibility of peanut hull particle for removal of three cationic dyes (methylene blue, brilliant cresyl blue and neutral red) from aqueous solution was investigated. The effects of various experimental parameters were examined and optimal experimental conditions were decided. Above the value of initial pH 4, three dyes studied could be removed effectively. The isothermal data fitted the Langmuir model or Freundlich model. The adsorption processes followed the pseudo-first-order rate kinetics. The results in this study indicated that peanut hull was an attractive candidate for removing cationic dyes from dye wastewater.

Adsorption↗