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At least 1,009 records · Page 56Linked to original sources
PubMed1988

The motor innervation of the soft palate. An anatomical study in guinea pigs and monkeys.

In an effort to gain a more precise understanding of the motor innervation of the soft palate, a neuroanatomical tracer (horseradish peroxidase) was injected into the vela of nine guinea pigs and four monkeys. After 48 h the animals were sacrificed and frozen frontal sections were appropriately reacted with tetramethylbenzidine and counterstained with neutral red, and then evaluated by means of light microscopy. In all specimens retrogradely labeled neurons appeared in the brain stem. The distribution patterns of these labeled cells were to a large degree comparable in both the guinea pigs and the monkeys. The complex motor innervation of the soft palate was found to involve at least five different centers, with the strongest staining seen in the nucleus ambiguus and the motor nucleus of the trigeminal nerve. Additional cells of origin were discernible in the retrofacial nucleus. Facial neurons, however, were labeled only occasionally. Findings also showed that a previously undescribed component from the hypoglossal nerve appears to be essential for lateral soft palate movement in both animal models.

Animals↗
PubMed1986

In vitro prediction of aminoglycoside ototoxicity.

The first step by which a basic aminoglycoside (AG) causes ototoxicity is thought to be electron binding to such acidic substances as phosphatidylinositol diphosphate and acidic glycosaminoglycans (AGAGs). We studied the competitive binding ability of AGs and basic dyes to AGAG in order to determine if this mechanism was indeed responsible for ototoxicity. The negative charge of heparin was the strongest among the AGAGs examined when the molar ratio of AG to AGAG was small. Toluidine blue was a better basic dye than acridine orange, methylene blue, alcian blue, or neutral red. After we mixed toluidine blue, heparin and an AG, the absorbance of free toluidine blue was measured at 625 nm. The difference in the free dye released by the well-established AG showed a fairly good correlation with the ototoxic activity found in vivo. However, the predicted ototoxicities of newly prepared AGs were greater than estimated when testing their effects on experimental animals. The basicity of AGs will determine their binding affinities to cochlear hair cell membranes and is an important factor in predicting ototoxicity.

Aminoglycosides↗
PubMed1975

Changes in pancreatic tryptophan in the rat in response to fasting. The effect of B-cytotoxic agents and variation through the oestrous cycle.

The concentration of tryptophan not incorporated into protein or polypeptides in the pancreas of male rats rose two- to three-fold in response to a 24 hrs period of food deprivation. On refeeding or intra-peritoneal administration of glucose the level of tryptophan in the pancreas fell, while that in the serum rose. The pancrease B-cytotoxic agents alloxan and streptozotocin both abolished this response to fasting, while neutral red (an A-cytotoxic agent) had no effect. It therefore appears that the tryptophan which accumulates in the pancreas during fasting is located mainly in the B-cells of the Islets of Langerhans. In female rats, the concentration of tryptophan in the pancreas was greater at dioestrus than at any other stage of the oestrous cycle. The increase in pancreatic tryptophan was maximal at metoestrus and minimal at oestrus.

Alloxan↗
PubMed1995

Effects of ozone on some biological activities of cells in vitro.

The aim of this work was to study the in vitro effect of ozone on the 70 kDa family of inducible heat shock proteins (HSPs70). We also performed tests to investigate possible toxic effects of ozone at the different doses employed. In human haematic mononucleated cells ozone at doses up to 20 micrograms/ml had no toxic effects and induced biosynthesis of the HSPs70. Biosynthesis of these proteins was greater at 40 micrograms/ml. In murine macrophages testing with tetrazolium salt (MTT), neutral red, and 2-deoxy-D-[1-3H]glucose uptake and study of the cell morphology showed a remarkable resistance or no toxic effects at a dose of 100 micrograms/ml also. Melanoma B16 murine cells assayed with the MTT test demonstrated less resistance to the toxic effects of ozone than normal cells. These results provide indications relevant to the problems of ozone therapy.

Animals↗
PubMed1979

Neutral protease activity in lymphocytes of Lewis rats with acute experimental allergic encephalomyelitis.

Lymphocytes from popliteal and inguinal lymph nodes of Lewis rats with acute EAE as a result of injection of lyophilized guinea pig myelin in Freund's complete adjuvant exerted strong proteolytic activity at neutral pH toward myelin basic protein. After injection of myelin the level of proteolytic activity remained about the same as that in lymphocytes from Freund's adjuvant-injected controls until about day 10 after injection, just before the onset of paralytic symptoms; then the proteolytic activity increased to approximately double its former level. Myelin basic protein was hydrolyzed by whole lymphocytes, but more activity was unmasked by homogenization. Similar results were also obtained using lymphocytes from thymus of EAE and control animals. Lymphocytes with high levels of proteolytic activity were not absorbed by glass wool, did not stain with neutral red, nor did they phagocytose antibody-coated sheep red blood cells. Thymus and lymph node lymphocytes cleaved myelin basic protein to three major peptides and a fourth minor peptide, while spleen lymphocytes hydrolyzed basic protein at only one point resulting in two peptides whose molecular weights added up to that of myelin basic protein. The protease activity was inhibited by 5 X 10(-3) M p-chloromercuribenzoate and by phenylmethyl sulfonyl fluoride, TPCK, and soybean trypsin inhibitor, therefore the enzymatic activity probably depends on a serine residue and a sulfhydryl group. The bulk of the enzymatic activity is mostly membrane bound with the highest specific activity and total activity contained in a lysosomal-mitochondrial fraction. In view of the infiltration of lymphocytes into the brain substance in acute EAE, it is suggested that these cells may contribute to the destruction of myelin which is usually attributed to the monocyte or macrophage.

Animals↗
PubMed1990

The evolution of focal ischemic damage: a metabolic analysis.

Focal cerebral ischemia in the rat was induced by left middle cerebral artery occlusion. The area of ischemia was determined by infusion of a qualitative perfusion indicator, neutral red. The temporal evolution of alterations in regional energy metabolism was assessed by direct microquantitative histochemical analysis of high-energy phosphates, glucose, glycogen, and lactate content of the tissue. Perfusion analyses demonstrated a perifocal region of diminished, but not absent perfusion up to 6 hr after occlusion. By 24 hr, there was an abrupt demarcation between perfused and nonperfused regions. Profound metabolic alterations were seen as early as 20 min after occlusion. Although there was an area of intermediate metabolic derangement in the more medial portions of the lateral ipsilateral cortex up to 6 hr, by 24 hr there was an abrupt transition from normal to abnormal cortex. No evidence of metabolic recovery was seen in this model of permanent occlusion.

Adenosine Triphosphate↗
PubMed1991

In vitro response of the brown bullhead catfish cell line, BB, to aquatic pollutants.

Established cell lines from brown bullhead catfish (BB) and rainbow trout (RTG-2) and primary cultures of cells derived from gill, fin, and gonad tissues from brown bullhead catfish were evaluated for use as bioindicators in the neutral red cytotoxicity assay. The BB and RTG-2 cells were compared after a 1 day exposure to chlorinated pesticides and after a 6-day exposure to various polycyclic aromatic hydrocarbons. The BB cells were more sensitive to both classes of chemicals. The sequence of toxicity for the BB cells was 4,4'-DDD. 4,4'-DDT greater than aldrin, 4,4'-DDE and 7,12-dimethylbenz(a)anthracene (DMBA) greater than 3-hydroxybenzo(a)pyrene (3-OH-B(a)P) greater than benzo(a)pyrene (B(a)P). For the RTG-2 cells, the sequence was aldrin greater than 4,4'-DDD greater than 4,4'-DDT greater than 4,4'-DDE and 3-OH-B(a)P greater than DMBA greater than B(a)P. The BB cells were also sensitive to benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)anthracene, and trans-7,8-dihydro-7,8-dihydroxybenzo(a)pyrene. The responses of BB and RTG-2 cells were compared with those of primary cultures after a 1 day exposure to B(a)P. After 1 day of exposure, the RTG-2 cells and primary cultures were more sensitive than the BB cells to B(a)P. Apparently, after 1 day of incubation the RTG-2 and primary cells metabolized greater amounts of B(a)P to cytotoxic metabolites, than did the BB cells. However, by 6 days of incubation, the BB cells were more sensitive to B(a)P than were the RTG-2 cells. A 6-day exposure to B(a)P was not performed with the primary cell cultures.

Animals↗
PubMed1981

Alkalinization of phosphorylase kinase-deficient muscle during tetanic contraction.

The intracellular pH of resting and stimulated muscle was monitored by two independent methods: measurement of pH in iodoacetate-treated homogenates of freeze-clamped tissue and the absorbance at 550-443 nm of intracellular neutral red dye in vivo. During tetanic stimulation, muscle of phosphorylase kinase-deficient mice shows a transient alkalinization whereas muscle in normal mice becomes more acid under similar conditions. The alkalinization appears to be caused by abnormally rapid AMP deamination associated with adaptation to phosphorylase kinase deficiency.

Animals↗
PubMed1993

Oxidative stress in fish cells: in vitro studies.

Bluegill sunfish BF-2 fibroblasts were used in the neutral red (NR) cytotoxicity assay to discern the toxicities of hydrogen peroxide (H2O2) and paraquat as indicated by their abilities to induce oxidative stress. The toxicity of H2O2 was markedly enhanced in BF-2 cells treated with the glutathione depleting agents, buthionine sulfoximine (BSO), maleic acid, and chlorodinitrobenzene; similar treatments did not sensitize the BF-2 cells to paraquat, a redox cycling xenobiotic. BSO treated BF-2 cells, however, were sensitized to nitrofurantoin, also a redox cycling chemical. Diethyldithiocarbamate, an inhibitor of superoxide dismutase, only weakly enhanced the sensitivity of the BF-2 cells to H2O2 and paraquat. 1,10-Phenanthroline, a chelator of Fe2+, reduced the cytotoxicity of H2O2 and paraquat, presumably by preventing hydroxyl radical formation in the Fenton reaction. Quin 2 AM, an intracellular chelator of Ca2+, markedly lessened the toxicity of H2O2, but not of paraquat; EGTA, an extracellular chelator of Ca2+, had no effect on the toxicity of H2O2 or paraquat. Apparently, perturbation of intracellular Ca2+ homeostasis is involved in H2O2 toxicity. For comparative purposes, some studies were performed with fathead minnow FHM epithelioid cells, BALB/c mouse 3T3 fibroblasts, and human HepG2 hepatoma cells. The BF-2 fibroblast/NR cytotoxicity red assay was shown to be a suitable model to study oxidative stress in fish.

3T3 Cells↗
PubMed1978

Biochemical Transformation of mouse cells by herpes simplex virus types 1 and 2: comparison of different methods for inactivation of viruses.

Comparison of methods to inactivate lytic properties of herpes simplex viruses revealed that ultraviolet irradiation, photodynamic procedures, and heat all destroyed infectivity effectively. Ability to biochemically transform thymidine kinase deficient cells to an enzyme positive phenotype was retained after limited exposure to heat or ultraviolet light but appeared to be destroyed by photodynamic methods employing neutral red. Exposure to 56 degrees C quickly and effectively destroyed transforming activity with lower temperatures being less effective. The most reproducible transforming assays were obtained following inactivation by ultraviolet light. Cell cultures developed by this procedure were virus-free but retained ability to synthesize virus-specific antigens.

Animals↗
PubMed1988

The use of fluorochromes in the cytochemical characterization of some phytoflagellates.

Sixteen fluorochromes were tested for the cytochemical characterization of two dinoflagellates (Amphidinuim carterae, Prorocentrum micans) and one chlorophycean flagellate (Dunaliella tertiolecta). Depending on the fluorochrome used, various cellular components (including the plasma membrane, thecal plates, pusule, trichocysts, nucleus, lipid bodies and vacuoles) were revealed. The different colours obtained from single or double fluorochrome staining enabled the differentiation and identification of most cellular components. Protoplasmic staining with Fluorescein diacetate suggested the occurrence of esterases in the three phytoflagellates. Rhodamine B, Neutral Red, FluoroBora P and Nile Blue revealed extensive occurrence of lipoid bodies in A. carterae, but Nile Blue showed considerable difference from the other stains in the inclusion size and intracellular location of these bodies. Chlortetracycline binding, and its inhibition by the Ca2+ionophore A23187, indicated that the plasma membrane, pusule system and trichocysts contain sites of Ca2+ binding. Calcofluor White ST proved superior to Congo Red and Lucifer Yellow in elucidating structural details of the thecal plates of P. micans. While Acridine Orange revealed the presence of surface-coat acidic polysaccharides, the fluoresceinated lectins established their glycoconjugate nature in all the three flagellates. Possible mechanisms of fluorochrome uptake are discussed.

Animals↗
PubMed1985

Electric pulse-induced fusion of mouse lymphoma cells: roles of divalent cations and membrane lipid domains.

Mouse leukemic lymphoblasts (L5178Y) brought into close contact by dielectrophoresis underwent cell fusion following the application of electrical pulses in the presence of electrolytes. The electrically fused cells became spherical after switching off the dielectrophoretic field. Fusion between a cell vitally stained with Janus Green and that with Neutral Red resulted in the homokaryon with a mixed color. Intracellular potentials simultaneously recorded from the two cells located on both sides of the homokaryon were identical. The fusion efficiency was remarkably dependent upon temperature, displaying a discontinuity at about 11 degrees C in the Arrhenius plot. The extracellular application of phospholipase-A2 or -C suppressed the fusion yield. Thus, it appears that the phospholipid domains play a crucial role in the electric pulse-induced cell fusion. Treatment of the cells with proteolytic enzymes markedly enhanced the fusion yield, presumably due to removing the glycocalix and/or giving rise to fusion-potent, protein-free lipid domains. The presence of millimolar concentrations of divalent cations (irrespective of Mg2+ or Ca2+) as well as of micromolar concentrations of Ca2+ (but not Mg2+) was prerequisite to the resealing of membranes suffered from electrical breakdown upon exposure to electric pulses. In addition, extracellular Ca2+ (but not Mg2+) ions at more than micromolar concentrations were indispensable for the cell fusion.

Animals↗
PubMed1981

Interaction of organic dyes with hepatic microsomal drug-metabolizing monoöxygenases in vitro.

Organic dyes such as malachite green, methylene blue, fuchsin, safranine T, neutral red, phenazine methosulphate, riboflavin, dichlorophenolindophenol, phenolphthalein, and fluorescein, inhibit hepatic microsomal mixed-function oxidases and, partly, enhance, partly, inhibit hepatic microsomal NADPH-dependent cytochrome c and neotetrazolium reductases, in contrast to other inhibitors of drug metabolism which do not affect cytochrome c reductase but only interact with cytochrome P-450.

Animals↗
PubMed1993

Effects of cisplatin and ORG.2766 in chick embryonic brain cell cultures.

The neurotoxicity of cisplatin and ORG.2766, both separately and in combination, was investigated using serum-free chick embryonic brain cell cultures. At low cisplatin concentrations glial cells were affected more than nerve cells. The onset of cisplatin toxicity was delayed, the major effects only being seen after the treatment was finished and when no free cisplatin was present in the culture medium. The data further indicate that the area under the graph of free cisplatin concentration in the culture medium against time (AUC) is a measure of cisplatin toxicity. The AUC of free cisplatin in the culture medium which causes a 50% reduction in the expression of glial fibrillary associated protein (GFAP) was similar to blood AUC values in humans known to induce neurotoxic effects in around 80% of patients. ORG.2766 at very high concentrations increased lysosomal activity, as measured by neutral red uptake, and the expression of GFAP. ORG.2766 did not influence the toxicity of cisplatin in culture.

Adrenocorticotropic Hormone↗
PubMed1992

Possible direct role of reactive oxygens in the cause of cutaneous phototoxicity induced by five quinolones in mice.

The mechanisms of phototoxicity induced in mice by five quinolone antibacterial agents were investigated using mouse 3T3 fibroblast cells and Balb/c mice. In the in vitro study, the cultured cells were exposed to ultraviolet-A (UVA) in the presence of the five quinolones lomefloxacin, enoxacin, ciprofloxacin, ofloxacin and DR-3355 (the s-isomer of ofloxacin). Cytotoxicity after irradiation was assayed by the neutral red and MTT assay methods, both of which revealed dose-dependent phototoxicity for all five quinolones. Phototoxicity was inhibited by the addition of catalase, and was augmented by the addition of superoxide dismutase. Dimethylthiourea (a hydroxyl radical scavenger) protected against phototoxicity induced by four quinolones, but not against that by enoxacin. These results indicated that superoxide anions, hydrogen peroxide and hydroxyl radicals were generated in solutions of these quinolones under UVA irradiation. In the in vivo study, mice were injected in the auricle with hydrogen peroxide. Ear swelling reactions appeared dose dependently. When irradiated, these reactions were significantly augmented. These data suggested that cutaneous phototoxicity in Balb/c mice is initiated by the generation of reactive oxygens in the target tissue, especially of hydroxyl radicals.

3T3 Cells↗
PubMed2000

Assessment of acute cyto- and genotoxicity of corrosion eluates obtained from orthodontic materials using monolayer cultures of immortalized human gingival keratinocytes.

Whilst a patient is undergoing orthodontic treatment, dental appliances based on non-precious metals or titanium remain in the oral cavity for up to several years. Throughout this period the appliance is in either direct or indirect contact with the oral mucosa. To investigate the possibility of cell damage occurring as a result of appliance corrosion, monolayer cultures of immortalized human gingival keratinocytes were assessed for acute cyto- and genotoxicity using the hexosaminidase assay and the Comet assay respectively. The materials tested included 1. a nickel-free wire, 2. a UK-1 bond, 3. nickel-free as well as nickel-containing brackets with and without color signature and 4. a titanium expansion screw. Each of the test materials was corroded in a solution consisting of equal amounts of lactic acid and sodium chloride (0.1 M) for 1, 3, 7 and 14 days. The cell cultures were then exposed to eluates exhibiting the highest ion concentrations. None of the eluates was found to exhibit acute cytotoxicity, regardless of the type of test system used. Qualitative assessment using neutral red dye for live cells and either trypan blue or propidium iodide to disclose dead cells failed to reveal any significant increase in cell damage when exposed cells were compared to control cultures. Unrestricted cell vitality was confirmed by quantifying viable cells through measurement of hexosaminidase enzyme activity. Furthermore, assessment of genotoxicity revealed no apparent DNA damage to immortalized gingival keratinocytes following exposure to the test eluates. Because the materials tested in this study were corroded using the exacting methods normally applied to precious metals or gold-containing alloys, the lack of either acute cyto- or genotoxic effects following exposure to the test eluates indicates that the materials tested exert no adverse effects on cells similar to those of the target tissue exposed to the materials in situ.

Cell Culture Techniques↗
PubMed1996

Cyto- and genotoxic effects of coordination complexes of platinum, palladium and rhodium in vitro.

The growing industrial use of platinum group elements as catalysts, especially in automobile exhaust detoxification (trimetal catalytic converters), is causing increasing occupational and environmental pollution. The cytotoxic and mutagenic properties of industrially used coordination complexes of platinum, palladium and rhodium were investigated using the neutral red cytotoxicity assay on two established cell lines and the Salmonella typhimurium/microsome test system (Ames test). Cytotoxic effects of the platinum complexes, measured as ED50, occurred at test concentrations of 0.2 mM. The analogous palladium salts tested were 3 times less toxic with ED50 being 0.6 mM, while the rhodium salts proved to be 30 times less toxic (ED50 = 6 mM). Levels of toxicity of the different complexes of a particular metal did not differ significantly from each other, which indicates that the metal itself is responsible for the toxic effects. In the Ames test, the spontaneous mutation rates increased by factors of 3 to 20 when the four tester strains were exposed to the platinum complexes. The analogous rhodium compounds proved to be considerably less mutagenic, and palladium demonstrated no mutagenic potential. As all of the four tester strains contain different mutations, the mutagenic potential of platinum and rhodium complexes appears to be based on a variety of mechanisms that damage DNA. From these in vitro experiments, it can be concluded that water-soluble complex salts of rhodium are less toxic and have a smaller mutagenic potential than the analogous platinum complexes. For palladium there is no evidence of any mutagenic property. From this point of view, the development of a catalytic converter containing predominantly palladium may be a possible means of minimizing potential health risks from this exhaust detoxification technique.

Animals↗
PubMed1996

Effect of anoxia and reoxygenation on antioxidant enzyme activities in immortalized brain endothelial cells.

The effects of anoxia and reoxygenation on major antioxidant enzyme activities were investigated in vitro in immortalized rat brain endothelial cells (RBE4 cells). A sublethal anoxic period of 12 h was assessed for RBE4 cells using the neutral red uptake test. Anoxia markedly influenced the specific activity of catalase and superoxide dismutase, with no major effect on glutathione peroxidase or glutathione reductase. After 24 h postanoxia, the superoxide dismutase activity modulated by the presence or absence of oxygen returned to control value. Damage and recovery of RBE4 immortalized rat brain endothelial cells in culture after exposure to free radicals and other oxygen-derived species provides a useful in vitro model to study anoxia-reoxygenation trauma at the cellular level.

Animals↗