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At least 1,513 records · Page 84Linked to original sources
PubMed1996

1,25-dihydroxyvitamin D3 increases the sensitivity of human renal carcinoma cells to tumor necrosis factor alpha but not to interferon alpha or lymphokine-activated killer cells.

Renal cell carcinoma is a chemotherapy-resistant tumor which is relatively responsive to immunotherapy. Immunotherapeutic regimes employ interferons or interleukin 2 with or without lymphokine-activated killer cells. Secondary cytokines, induced by interleukin 2 or interferon, may have an important impact on their anti-neoplastic activity. Notable among them is tumor necrosis factor (TNF alpha). We assessed the effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on the susceptibility of the human renal cell carcinoma cell line SK-RC-29 to the cytotoxic and cytostatic actions of TNF alpha, interferon alpha and lymphokine-activated killer cells. Using uptake of the vital dye neutral red as an indicator of viable cell number, we found that addition of 1,25(OH)2D3 (100 nM) to TNF alpha (30 ng/ml)-treated cultures resulted in a 2.6 +/- 0.2-fold (mean +/- S.E.) increase in the cytotoxic effect of the cytokine. The potentiating effect of 1,25(OH)2D3 was dose-dependent, and significant at concentrations equal to or higher than 10 nM. Another dihydroxylated vitamin D metabolite, 24,25(OH)2D3, had no effect on TNF alpha action. The cytotoxic effect of TNF alpha increased whereas the potentiation by 1,25(OH)2D3 decreased with cell density in culture. 1,25(OH)2D3, in contrast to its potentiating effect on TNF alpha action, did not modulate the cytostatic effect of interferon alpha or the susceptibility of SK-RC-29 to killing by lymphokine-activated killer cells. The findings reported here may explain some of the in vivo anti-tumor activity of 1,25(OH)2D3 and provide a rationale for the employment of active vitamin D analogs during immune anti-cancer therapy.

Calcitriol↗
PubMed2006

Lysosomal membrane stability in laboratory- and field-exposed terrestrial isopods Porcellio scaber (Isopoda, Crustacea).

Two established methods for assessment of the cytotoxicity of contaminants, the lysosomal latency (LL) assay and the neutral red retention (NRR) assay, were successfully applied to in toto digestive gland tubes (hepatopancreas) of the terrestrial isopod Porcellio scaber (Isopoda, Crustacea). In vitro exposure of isolated gland tubes to copper was used as a positive control to determine the performance of the two methods. Lysosomal latency and the NRR assay were then used on in vivo (via food) laboratory-exposed animals and on field populations. Arbitrarily selected criteria for determination of the fitness of P. scaber were set on the basis of lysosomal membrane stability (LMS) as assessed with in toto digestive gland tubes. Decreased LMS was detected in animals from all polluted sites, but cytotoxicity data were not in agreement with concentrations of pollutants. Lysosomal membrane stability in the digestive gland tubes of animals from an environment in Idrija, Slovenia that was highly polluted with mercury (260 microg/g dry wt food and 1,600 microg/g dry wt soil) was less affected than LMS in laboratory animals fed with 5 and 50 microg Hg/g dry weight for 3 d. This probably indicates tolerance of P. scaber to mercury in the mercury-polluted environment and/or lower bioavailability of environmental mercury. In animals from the vicinity of a thermal power plant with environmental mercury concentrations three to four orders of magnitude lower than those in Idrija, LMS was severely affected. In general, the LL assay was more sensitive than the NRR assay. The LMS assay conducted on digestive gland tubes of terrestrial isopods is highly recommended for integrated biomarker studies.

Animals↗
PubMed2001

A comparison of biomarker responses in the earthworm Aporrectodea caliginosa to the organophosphorus insecticides diazinon and chlorpyrifos.

Three biomarkers in Aporrectodea caliginosa Savigny were evaluated for their ability to detect exposure to organophosphorus insecticides, and these physiological responses were related to effects on growth and life-table parameters. Adult and juvenile earthworms were exposed to a laboratory-simulated field rate (low concentration) and a higher sublethal concentration of diazinon and chlorpyrifos. After a four-week exposure, juveniles were evaluated for cholinesterase activity, glutathione S-transferase activity, and growth, and adults were evaluated for the lysosomal neutral red retention assay (NRRA) and growth. Cholinesterase activity and the NRRA were more sensitive than growth in each age group for detecting exposure to the pesticides. Life-table parameters were evaluated in earthworms exposed as juveniles and as adults. Maturation was less sensitive to pesticides than was cocoon production. Growth and cocoon production in earthworms exposed as juveniles appeared to be more sensitive to organophosphorus insecticides than earthworms exposed as adults. Life-table responses in juveniles may, therefore, be more predictive of long-term impacts of organophosphorus insecticide applications on populations than responses in adults. Biomarker responses occurred at similar or lower concentrations than those causing an adverse effect on cocoon production and cocoon viability, indicating their usefulness in risk assessment for predicting ecologically relevant assessment end points.

Age Factors↗
PubMed1981

In vitro growth of human gingival fibroblasts on root surfaces of endodontically treated teeth.

Controversy exists over the potential for new connective tissue attachment to dentin of endodontically-obturated teeth following periodontal therapy. The purpose of this study was to determine whether cultured human gingival fibroblasts would grow in vitro on planed dentin surfaces of endodontically-treated teeth. A model similar to that of Aleo et al. was developed using extracted endodontically-treated human teeth. This model consisted of longitudinally sectioning 10 teeth, root planing one section only, and incubating both sections with a suspension of human gingival fibroblasts. Fibroblast growth was determined by staining with neutral red and trypan blue. The criterion for growth was staining of the complete root surface. All root areas with attached periodontal fibers displayed staining, as well as the complete root surface of all planed sections. Unplaned sections did not stain on root areas formerly exposed to the oral environment owing to periodontal disease, a finding consistent with the results of Aleo et al. Our results indicate that root canal therapy does not interfere with in vitro growth of fibroblasts on planed dentin surfaces of endodontically-treated teeth. Extrapolation to a clinical situation would indicate that normal healing may be expected after periodontal surgery on tissues adjacent to root planed endodontically-treated teeth.

Cell Division↗
PubMed2006

Indirect kinetic spectrophotometric determination of hydroxylamine based on its reaction with iodate.

A simple, precise and accurate method is proposed for rapid determination of trace amounts of hydroxylamine based on the reaction of hydroxylamine with iodate in acidic media. The reaction of neutral red by the produced nitrite ion was used to monitor the reaction spectrophotometrically at 525 nm by a fixed time method. Hydroxylamine in the range of 0.0400-1.200 microg mL(-1) could be determined. The relative standard deviation for 10 determinations of 0.500 microg mL(-1) hydroxylamine was 1.81% and the limit of detection was 0.010 microg mL(-1). The proposed method was applied to the determination of hydroxylamine in water samples with satisfactory results.

Alcohols↗
PubMed1996

Toxicity of amiodarone on mouse pulmonary endothelial cells cultured with or without alveolar macrophages.

This study was designed to specify the toxicity of amiodarone toward mouse pulmonary endothelial cells in comparison with that of another cationic amphiphilic drug, i.e., mianserin. These examinations were performed in the absence and presence of mouse alveolar macrophages under transmembrane co-culture or in direct contact with the endothelial cells to assess the contribution of macrophages to the toxicities toward the endothelial cells. As a result of 24-hr treatment, amiodarone caused a decrease in cell viability, in H(+)-ATPase, acid sphingomyelinase, and acid phospholipase A2 activities, and in neutral red uptake, and an increase in permeability of the endothelial cells. Because the magnitude of changes in the endothelial cells was the greatest under direct contact with macrophages, and was the mildest without macrophages, macrophages were considered to enhance the toxicity of amiodarone toward the endothelial cells. Additionally, the toxic effect of amiodarone on the cells was depressed by pretreatment of them with docosahexaenoic acid (DHA) or alpha-tocopherol for 2 days and co-treatment with these agents for 1 day, but not with prednisolone or indomethacin co-treatment. DHA and alpha-tocopherol protected endothelial cells from the toxicity of amiodarone. The effect was more potent for DHA than alpha-tocopherol.

Amiodarone↗
PubMed2001

In vitro evaluation of acute cytotoxicity of human chemically treated allografts.

In order to minimize the risk of contamination associated with tissue transplantation, tissue banks commonly chemically treat the tissues whenever possible. As viral inactivation uses agents lethal to microorganisms, it is imperative to assure that chemically inactivated tissue remains biocompatible. In vitro assays can be an effective means to assess the acute cytotoxicity of chemically treated human allografts. We have used different types of cells cultured in the presence of treated tissue extract. A standard cell line, a human fibroblast (WI38), which was the same for all the samples, was chosen. In addition, as the banked tissues (bone and fascia lata) were prepared to be used in bone or as a dura mater substitute, two other cell types were also used: an osteoblastic cell line (SaOS-2) and a neuronal cell line (Neuro 2A). Cytotoxic assessment was performed by qualitative evaluation of cell morphology based on confluence, granulation, vacuolization and swelling analysis. In addition, quantitative methods based on the use of neutral red (NR) and 3- (4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide (MTT) were assayed. Qualitative and quantitative evaluation of fascia lata and bone extracts did not show deleterious effects on cell cultures. These results show that in vitro methods can be appropriate to select a non-toxic procedure before it is used in the human body and that several strong chemical treatments can result in a tissue suitable for human.

Journal Article↗
PubMedDate not supplied

[The effect of propylthiouracil on function of phagocytic peripheral blood cells in persons with thyroid hyperfunction].

INTRODUCTION: It is known that hyperthyroidism as well as thyrosuppressive therapy can influence the cells of immunological system. OBJECTIVE: To examine the function of phagocyte cells in persons with hyperthyroidism and to examine if propylthiouracil (PTU) influences this function. METHOD: The study included 15 patients with hyperthyroidism and 10 healthy persons. The parameters of phagocytic activity of mononuclear and polymorphonuclear leucocytes were tested by method of ingestion of particles of inactivated yeast labeled with neutral-red. RESULTS: It was demonstrated that patients with hyperthyroidism, before the onset of therapy as well as 14 days after introduction of PTU, had decreased number of leucocytes (before PTU: 6.7 +/- 3.2 x 10(9)/l, after PTU: 6.1 +/- 2.0 x 10(9)/l and control: 8.0 +/- 1.6 x 10(9)/l; p=0.039), PMN leucocytes (before PTU: 3.9 +/- 2,4 x 10(9)/l, after PTU: 3.5 +/- 1.6 x 10(9)/l and control: 4.8 +/- 0.9 x 10(9)/l; p=0.037) and number of phagocyte PMN cells (before PTU: 0.9 +/- 0.9 x 10(9)/l, after PTU: 0.9 +/- 0.7 x 10(9)/l and control: 1.3 +/- 0.6 x 10(9)/l; p<0,05), but they had increased index of phagocytosis (before PTU: 2.0 +/- 0.2, after PTU: 1.9 +/- 0.2 and control: 1.7 +/- 0.2; p=0.029), while capacity of phagocytosis remained unchanged (before PTU: 1.9 +/- 1.7 x 10(9)/l, after PTU: 1.6 +/- 1.9 x 10(9)/l and control: 2.4 +/- 1.4 x 10(9)/l; p>0.05). The number of mononuclear leucocytes and parameters of phagocytic activity of mononuclear phagocytes in persons with hyperthyroidism did not change significantly in comparison with the control group. CONCLUSION: Patients with hyperthyroidism had decreased number of leucocytes, PMN leucocytes and number of phagocyte PMN cells, and increased index of phagocytosis, while capacity of phagocytosis remained unchanged. The number and parameters of phagocytic activity of mononuclear leucocytes did not change. PTU therapy had no effect on the examined parameters.

Adult↗
PubMed1977

Cytochemical aspects of Mercenaria mercenaria hemocytes.

The hemocytes of the hard clam M. mercenaria were of three types: an agranulocyte, a small, and a large granulocyte. The agranulocyte, with only a thin periphery of cytoplasm surrounding the nucleus, had no visible cytoplasmic granules in living preparations but did exhibit a few centers of nonspecific esterase activity. This cell type represented 2% of the hemocyte population. The small granulocyte possessed four distinct granule types and comprised 61% of the total cell population. Large granulocytes accounted fro 37% of all hemocytes. While they contained the same four granule types identified in the small granulocyte, only one-third the total number were present. The nucleus of all three hemocyte types appeared morphologically similar. The four types of granules observed were a blunt, dot-like, a refractile and a filamentous granule. Blunt granules were identified as mitochondria, based on their ability to reduce Janus Green B to diethyl safranin, the presence of NADH dehydrogenase activity and boundary staining with Sudan black B. Dot-like granules were identified as lysosomes on the basis of neutral red staining, localization of acid phosphatase and nonspecific esterase activity and staining with Sudan black B. Refractile granules were demonstrated to be membrane-bound, lipid-filled structures that reacted positively with Sudan black B and Oil red O, respectively; these granules act as lipid storage centers. Nuclear similarity of the three cell types suggest that these cells might represent different stages of maturity, rather than three distinct cell lines. This was also indicated by the similar yet graded cytochemical reactions and the varying degree of motility and phagocytic activity demonstrated by hemocyte types.

Animals↗
PubMed2000

Detection of cell detachment activity induced by Moraxella bovis.

OBJECTIVE: To characterize the effect that filtrate obtained from cultures of Moraxella bovis has on cultured corneal epithelial cells and other types of cultured mammalian cells. SAMPLE POPULATION: Cultured hamster corneal epithelial cells, bovine epithelial cells, and several transformed cell lines exposed to culture filtrate from a pathogenic isolate of M bovis. PROCEDURE: Moraxella bovis was cultured, and bacteria were removed by filtration. The resulting bacterial culture filtrate was incubated with various types of cultured cells, and effects of the filtrate on detachment of various mammalian cell types was quantified by the use of neutral red dye. Additionally, bacterial culture filtrate was treated with protease inhibitors as well as trypsin and heat prior to incubation with cultured mammalian cells. RESULTS: Bacterial culture filtrate of M bovis caused all types of cultured cells to detach from each other and from the substrate, with the maximal effect evident 2 hours after initiating incubation. Detached cells were alive, and detachment was reversible. Serine protease inhibitors (phenylmethylsulfonylfluoride and alpha2-macroglobulin) inhibited cell detachment attributable to bacterial culture filtrate. Heating and treatment with trypsin also inhibited cell detachment. CONCLUSIONS AND CLINICAL RELEVANCE: Moraxella bovis produces a soluble factor that causes reversible detachment of cultured cells. This activity may play a role in the pathogenesis of infectious bovine keratoconjunctivitis.

Animals↗
PubMed1989

Effects of corn grinding and time of corn feeding on growth, starch utilization and digesta passage characteristics of growing steers fed hay-based diets.

Two forms of corn, whole (WC) and ground (GC), were fed with hay (WH; 900) or 4 h after hay (AH; 1300) feeding to evaluate their effects on growth, starch utilization and digesta passage characteristics in growing steers. Twenty-four Angus steers with ad libitum access to fescue hay were individually limit-fed ground or whole corn (2.27 kg/d) in a 2 x 2 factorial arrangement of treatments: GC- WH, GC-AH, WC-WH and WC-AH. Average daily gain was improved with feeding GC (P less than .08), especially when fed at the same time as hay. Fecal starch (%) was less (P less than .001) for GC (7.07) than for WC (15.68). No difference was observed in rate of liquid or solid (hay) passage. Mean retention time (MRT) of whole corn (stained with neutral red and crystal violet) was decreased (P less than .07), and rate of corn passage tended to be faster for steers fed WC-AH than for those fed WC-WH. Although time of corn feeding had no effect on performance, steers fed WC-AH had more whole corn particles recovered from the feces and the MRT for whole corn particles was reduced, indicating that time of supplementation may affect passage characteristics. Altering time of supplement feeding may have applications in other feeding situations, such as with protein supplementation where ruminal escape would be advantageous.

Animal Feed↗
PubMed1985

Acid secretion and mucosal blood flow in the distal and proximal parts of the canine parietal cell mass in response to cholinergic stimulation.

Dogs provided with one denervated gastric pouch in the distal part of the corpus fundus and another of equal size in the proximal part were studied during stimulation with bethanechol chloride. Dose-response curves were determined for acid output and for mucosal blood flow, which was measured with the neutral red technique. ED50 for acid output was almost identical for the two pouches, giving a value of 1.13 (median) for the ratio of ED50 proximal pouch to ED50 distal pouch, which is between the ratios of 3.54 and 0.65 noted for pentagastrin and histamine, respectively in earlier investigations. The ED50 for blood flow was significantly lower than that for the simultaneous acid output, with a value of 0.28 for the ratio of ED50 blood flow to ED50 acid output, which gives an intermediate position between the ratios for pentagastrin (0.13 and 0.21 for the distal and proximal pouch, respectively) and histamine (0.61 and 0.73) obtained in earlier investigations. It could be hypothesized that the above differences in ratio between these three agonists reflect a difference at the receptor level of the parietal cells and the arterioles.

Animals↗
PubMed1985

Exogenous serotonin and gastric mucosal blood flow in conscious dogs.

The effects of serotonin on pentagastrin- and bethanechol-stimulated gastric mucosal blood flow (GMBF) and acid secretion were evaluated. Conscious gastric fistula dogs were used, with neutral red clearance as the method to estimate the mucosal blood flow. Serotonin inhibited the acid secretion, with a counteracting effect of propranolol and methysergide. Serotonin inhibited the pentagastrin- and bethanechol-stimulated GMBF after 15 min of infusion. The ratio between GMBF and acid secretion was increased during serotonin infusion, which suggests primary and independent changes in both variables. Propranolol and methysergide counteracted the serotonin inhibition of the GMBF. It may be concluded from this study that the acid-inhibitory effect of serotonin is not mediated by changes in the GMBF. The actions of serotonin on acid secretion and GMBF are mediated by specific receptors.

Animals↗
PubMed1986

Somatostatin increases the ratio between gastric mucosal blood flow and gastric acid and pepsin secretion in dogs.

The effects of somatostatin on gastric mucosal blood flow (GMBF), acid secretion, and pepsin secretion were evaluated. Conscious gastric fistula dogs were used, with neutral red clearance as the method for estimating the mucosal blood flow. Somatostatin inhibited the pentagastrin- and bethanechol-stimulated gastric acid and pepsin secretion and resulted in an absolute decrease in mucosal blood flow. The ratios between GMBF and secretion (acid and pepsin) were increased during somatostatin infusion, which suggests a relative increase in mucosal blood flow and independent inhibition of gastric secretion. It may be concluded from this study that the acid- and pepsin-inhibitory effects of somatostatin are not mediated by changes in the GMBF.

Animals↗
PubMedDate not supplied

Toxicity monitored with a correlated set of cell-culture assays.

A set of assays for toxicity has been developed in which cell cultures serve as an alternative to toxicity testing in vivo. One test is the assessment of the highest concentration of toxicant which produces minimal morphological alterations in cell cultures, followed by the determination of the amount of neutral red dye uptake by the cells. A second test is based on 50% inhibition of uptake of [3H]uridine after incubation of the cultures with the toxicant. There is good agreement between these assays in the rank correlation of a broad spectrum of compounds tested, as well as with the data from Draize rabbit eye irritancy tests in vivo.

Animal Testing Alternatives↗
PubMed1993

Cytotoxicity of tacrine and velnacrine metabolites in cultured rat, dog and human hepatocytes.

Clinical trials with tacrine (THA) and its principal (1-OH) metabolite (velnacrine) for the treatment of Alzheimer's disease have been hampered by adverse hepatic events that were undetected in preclinical studies. As part of integrated in vivo/in vitro efforts to characterize the role of metabolites in these events, cultured cells were evaluated for their suitability for further mechanistic studies. The relative cytotoxic potentials of THA, three monohydroxy metabolites of THA (including velnacrine, a racemate), the two velnacrine enantiomers, and several known and suspected dihydroxy velnacrine metabolites were determined. Cytotoxicity was evaluated in 24-hour cultures by morphology and by the Neutral Red Uptake Assay. All test articles were evaluated in primary rat hepatocytes and in a human hepatoma cell line (HepG2). THA and velnacrine were also tested in a rat hepatoma cell line (H4) and in primary dog hepatocytes. The metabolic competency of each cell type was determined. Sensitivity to THA and velnacrine was greatest in H4 cells, followed by primary rat and HepG2 cells; dog cells were least sensitive. In HepG2 cells, THA was clearly more cytotoxic (LC50:54 micrograms/ml) than its monohydroxy metabolites (LC50 values: 84 to 190 micrograms/ml); dihydroxy velnacrine metabolites were the least cytotoxic (LC50 values:251 to 434 micrograms/ml); the relative order was comparable in primary rat hepatocytes. Roles for reactive metabolites and/or altered metabolic capabilities of Alzheimer's patients are suggested.

Alanine Transaminase↗
PubMed1993

Change of membrane potential is not required for the tumour necrosis factor-alpha mediated cytotoxicity.

Recent evidence has been demonstrated that trimeric tumour necrosis factor-alpha (TNF) itself is a channel forming molecule and incubation of TNF with TNF-sensitive tumour cell line U937 increases the plasmalemmal Na+ permeability (21). Therefore, membrane potential (Em) may play a role in the cytotoxicity mediated by TNF. Results in our study demonstrate that: 1) TNF did not induce any changes of Em of L-929 cells but gramicidin and valinomycin produced positive responses as measured by two fluorescent probes, bis-oxonol and dis-C3-(5). 2) Exogenously imposed membrane depolarization by gramicidin or high potassium buffer did not attenuate the TNF-mediated cytotoxicity in L929 cells. 3) When the Em of L-cells was clamped at K(+)-equilibrium potential, TNF showed a dose-dependent cytotoxicity (determined by cell morphology and neutral red uptake assay) which was very similar to the normal TNF cytotoxic action. Taken together, evidence in our study illustrates that membrane depolarization or hyperpolarization is not required for TNF-mediated cytotoxicity.

Animals↗
PubMed1975

Studies in gram staining.

Gram-negative bacteria stained with crystal violet are decolorized by 95% alcohol within 2 min, whereas Gram-positive bacteria require at least 3 min treatment. Aqueous solutions of safranin, neutral red, and fuschsin replace crystal violet from stained Gram-positive bacteria more quickly than alcohol alone, and alcoholic solutions of these counterstains are in most cases still more effective. Treatment of crystal violet-stained organisms with alcoholic safranin (0.25%) for 15 sec will distinguish Gram-positive bacteria (violet) from Gram-negative bacteria (pink). Alcohol containing very low concentrations of iodine generally decolorizes crystal violet-stained Gram-positive bacteria more quickly than alcohol alone. Increasing concentrations of iodine in alcohol reduce the rate of decolorization of stained bacteria, but stained Gram-negative bacteria are still readily decolorized. The addition of 0.1% iodine to alcohol increases the rate of extraction of crystal violet by alcohol from Gram-negative organisms, but delays extraction of dye from Gram-positive organisms, and this applies when counterstain is also present. A two-solution modification of Gram staining is described in which crystal violet-stained bacteria are treated with an alcoholic solution of safranin, fuchsin, and iodine.

Bacteria↗