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PubMed2002

Protective effect of soybean saponins and major antioxidants against aflatoxin B1-induced mutagenicity and DNA-adduct formation.

Saponins from various plant sources have been suggested as possible anticarcinogens. Major dietary sources of saponins include legumes such as soybeans. This study was performed to determine the effect of soybean saponins on aflatoxin B(1)(AFB(1))-induced mutagenicity and AFB(1)-DNA adduct formation using Salmonella typhimurium and human liver hepatoma (HepG2) cells, respectively. Major antioxidants including L-ascorbic acid, alpha-tocopherol, all-trans-retinol, and butylated hydroxytoluene (BHT), previously reported to possess antimutagenic activity, were used as test materials to evaluate the relative effectiveness of saponins. Results indicated antimutagenicity was in the order of BHT > saponins > alpha-tocopherol > L-ascorbic acid. Soybean saponins exerted a significant effect, inhibiting the mutagenicity of AFB(1) by 52%, 64%, and 81% at concentrations of 600, 900, and 1,200 microg per plate, respectively. The amount of tritiated AFB(1) metabolites-DNA adducts formed in HepG2 cells was significantly reduced when cells were preincubated with 10 or 30 microg/ml of test materials. Soybean saponins inhibited AFB(1)-DNA adduct formation by 50.1% at a concentration of 30 microg/ml, whereas L-ascorbic acid and BHT reduced adduct formation by 38.4% and 32.6%, respectively, at the same concentrations. These results indicate that soybean saponins possess not only a significant antimutagenic activity but a strong inhibitory action against carcinogen-induced DNA damages. Soybean saponins possibly block the initiation stage of carcinogenesis, and further studies are required to elucidate the mechanisms of action.

Aflatoxin B1↗
PubMed1986

Differentiation without cleavage: multiple cytospecific ultrastructural expressions in individual one-celled ascidian embryos.

Multiple states of differentiation developed within the same undivided egg cytoplasm of ascidian zygotes cleavage-arrested with cytochalasin B. Complex ultrastructural traits of up to four quite diverse cell lineage components were observed in regions of the common cytoplasm in such multinucleate homokaryons of Ciona intestinalis: epidermal, muscle, notochordal, and neural. Almost all specimens among those selected as showing differentiation contained two such features, half of them had at least three, and a few expressed all four. The histospecific morphological characteristics noted were the extracellular test material of epidermal cell origin, muscle myofilaments and myofibrils, sheath components (leaflets and filaments) associated with notochordal cells, and the particular localized combinations of microtubules, filamentous structures, and cilia indicative of neural tissues. Cleavage-arrested one-celled embryos of Ascidia ceratodes served to demonstrate that those which were found cytochemically to contain muscle acetylcholinesterase always had myofibrils and myofilaments. Other arrested zygotes of Ascidia (unstained specimens) also had quite fully formed test material as well as myofilaments and myofibrils. The occurrence within the same cell of so many specific markers of diverse pathways of development is consistent with a theory about a primary level of regulation based on autonomous gene activation factors already present in the fertilized egg. If further investigation substantiates a real cytoplasmic continuity within these cleavage-arrested embryos, other theories that invoke cell interactions, temporal sequences of metabolically distinct microenvironments, and gradients of substances as causes of determinative change seem inadequate to account for the coexisting expressions of differentiation described here.

Cell Differentiation↗
PubMed1982

Subchronic dermal toxicity study of allyl methacrylate in rabbits.

A 28-day subchronic dermal toxicity of allyl methacrylate (AMA) was conducted in New Zealand white rabbits. Groups of six male and six female rabbits were treated with the test material at dose levels of 0, 25, 50 and 100 mg/kg/day for four weeks. One satellite group of male and female rabbits was also treated with 100 mg/kg/day of AMA. No overt signs of toxicity or abnormal behavior were seen among the rabbits during the treatment period. Two females from the 50 mg/kg/day group and two females at the highest dose level died during the course of the study. No mortalities and no significant adverse effects were observed in the low dose and control rabbits. Males treated with the highest dose level exhibited reduced weight gain and lower food consumption. The test material has no significant adverse effects on serum biochemistry, urine and hematological parameters or absolute and relative organ weights. No chemical related gross pathological alterations were observed in any of the organs or tissues examined at the time of necropsy except slight hemorrhage in the fascia of the skin of rabbits treated with 100 mg/kg/day of AMA. There were no significant chemical related microscopic changes found in any of the test rabbits. The animals of the satellite group appeared fully recovered following the 28-day dermal exposure to AMA. These results suggest that it is unlikely that AMA will present a significant health hazard from skin contact under normal conditions of industrial handling.

Acrylates↗
PubMed2005

Penetration of ammonium perfluorooctanoate through rat and human skin in vitro.

Rat and human epidermal membranes were mounted onto in vitro diffusion cells with an exposure area of 0.64 cm2, and skin integrity was confirmed using electrical impedance. Following membrane selection, Fluorad FC-118, a 20% aqueous solution of ammonium perfluorooctanoate (AFPO), was applied to the epidermal surface of each skin replicate at approximately 150 microL/cm2 and the donor chamber opening occluded with Parafilm. Serial receptor fluid samples were collected hourly from 1 to 6 h and at 12, 24, 30, and 48 h and analyzed by liquid chromatography-mass spectrometry (LC-MS) for APFO anion (PFO-). For rat skin, the time to steady-state penetration (6500+/-3000 ng APFO x cm(-2) x h(-1)) occurred in less than 12 h, which was sustained until termination (48 h). Based on the concentration of the applied test material, the permeability coefficient (Kp) for APFO in rat skin was calculated to be 3.25+/-1.51 x 10(-5) cm/h. By end of the 48-h exposure period, only a small portion of the total APFO applied (1.44+/-1.13%) had penetrated through rat skin. For human skin, steady-state penetration of APFO (190+/-57 ng APFO x cm(-2) x h(-1)) was reached by 12 h. Based on the concentration of the applied test material, the permeability coefficient for APFO in human skin was calculated to be 9.49+/-2.86 x 10(-7) cm/h. By the end of the 48-h exposure period, only a negligible amount of the total APFO applied (0.048+/-0.01%) had penetrated through human skin. Thus, under infinite dose and occlusive conditions, the steady-state penetration of APFO from a 20% solution was approximately 34-fold faster through rat skin than human skin.

Animals↗
PubMed1999

Histological changes in the rat common carotid artery following simultaneous topical application of cotton sheet and cyanoacrylate glue.

Histological changes in and around the arterial walls of rats were investigated following simultaneous topical application of cotton sheet and cyanoacrylate glue. The bilateral common carotid arteries were exposed using sterile techniques, and the test materials were applied to the right artery. The left artery served as a control. Changes in arterial histology were evaluated at 2 weeks, 1 month, 2 months, and 3 months after surgery. Extensive inflammation consisting primarily of histiocytes and multinuclear giant cells was observed around the materials, but tended to decrease by 3 months. Necrosis in the media and fibrosis in the adventitia initially appeared around 2 weeks, and became advanced by 2-3 months. At 2-3 months, disruption of elastic fibers and marked fibrosis in the media were seen, and endothelial proliferation in the intima appeared. Intimal proliferation was observed at both the experimental and other sites of the vessels. The present results suggest that simultaneous use of the test materials can cause the arterial occlusive lesions observed following aneurysmal surgery.

Animals↗
PubMed2001

The effect of thermocycling on the fracture toughness and hardness of core buildup materials.

STATEMENT OF PROBLEM: Thermocycling has been shown to cause surface degradation of many dental materials, but its effect on the fracture toughness and hardness of direct core buildup materials is unknown. PURPOSE: This study was designed to determine the effect of thermocycling on the fracture toughness and hardness of 5 core buildup materials. MATERIAL AND METHODS: Fifteen specimens were prepared from each of the following materials: Fluorocore, VariGlass VLC, Valiant PhD, Vitremer, and Chelon-Silver. American Standard for Testing Materials guidelines for single-edge notch, bar-shaped specimens were used. Ten specimens of each material were thermocycled for 2000 cycles; the other 5 specimens were not thermocycled. All specimens were subjected to 3-point bending in a universal testing machine. The load at fracture was recorded, and the fracture toughness (K(IC)) was calculated. Barcol hardness values were also determined. Data were analyzed with 1-way analysis of variance and compared with the Tukey multiple range test (P<.05). Pearson's correlation coefficient was also calculated to measure the association between fracture toughness and hardness. RESULTS: Fluorocore had the highest thermocycled mean K(IC) and Valiant PhD the highest non-thermocycled K(IC). Chelon-Silver demonstrated the lowest mean K(IC) both before and after thermocycling. One-way analysis of variance demonstrated significant differences between conditions, and the Tukey test showed significant differences (P<.05) between materials for both conditions. Most specimens also showed significant hardness differences between conditions. Pearson's correlation coefficient indicated only a mild-to-moderate correlation between hardness and fracture toughness. CONCLUSION: Within the limitations of this study, the thermocycling process negatively affected the fracture toughness and hardness of the core buildup materials tested.

Acrylic Resins↗
PubMed1979

A rat bioassay for measuring the comparative availability of carbohydrates and its application to legume foods, pure carbohydrates and polyols.

An assay was developed to evaluate the bioavailability of dietary carbohydrate by slope-ratio analysis of weight gain and plasma ketones of rats fed a carbohydrate-free diet supplemented with glucose as a standard and selected food items, pure carbohydrates and polyols. The diet was based on 35% food grade oleic acid, 12% casein protein supplemented with methionine (0.3%) and arginine (0.2%), 7.5% soybean oil, 37% cellulose, minerals and vitamins. Glucose, as the reference standard, or test materials were incorporated in the diet by replacing equi-energetic amounts of oleic acid and adjusting cellulose to equalize total weight. Optimal levels of protein (casein) and triglyceride (soybean oil) in the basal diet were defined as those levels above which additional protein or fat would serve only to provide endogenous glucose from their glucogenic amino acids and glycerol constituents. A standard dose-response curve was obtained by feeding diets containing 0%, 1% and 2% glucose. Similar dose response curves were obtained by feeding test materials. Under these experimental conditions, additional glucose or additional protein were growth stimulating and casein had approximately 50% of the value of an equal weight of glucose, which was consistent with its content of glucogenic amino acids. The specific carbohydrate value of a food was estimated in the assay by subtracting the calculated glucogenic value of its digestible protein from the total response. The apparent availability of the carbohydrates (i.e., nitrogen-free extract) in soybean meal, lima bean (Phaseolus lumatus), and chick pea (Cicer arietinum) were 35, 70, and 80%, respectively, as available as glucose. Galactose, a 1:1 mixture of galactose + glucose, fractose and starch were as available as glucose. Lactose, ribose, sorbitol, and xylitol were 50 to 65% as available as glucose while mannitol and inulin were not available to a significant extent. Possible metabolic bases for these differences are discussed.

Amino Acids↗
PubMed2006

Effect of mineral trioxide aggregate on proliferation of cultured human dental pulp cells.

AIM: To investigate the effect of mineral trioxide aggregate (MTA) on the proliferation of human dental pulp (HDP) cells ex-vivo. METHODOLOGY: Human dental pulp cells were cultured with MTA or calcium hydroxide-containing cement (Dycal) using culture plate inserts. Control cells were cultured with culture plate inserts only. Cell proliferation was measured for up to 14 days using a Cell Counting kit, and the concentration of calcium ions released from the tested materials was assessed using a Calcium E-test kit. To confirm that the effect of MTA was attributable to released calcium ions, cell proliferation was measured in the presence of exogenous calcium chloride as a source of calcium ions while in the absence of MTA. RESULTS: Mineral trioxide aggregate significantly stimulated cell proliferation after 12 days, whereas Dycal had no such effect. The number of calcium ions released from MTA was significantly higher than that released from Dycal. Following the addition of calcium chloride, cell proliferation increased in a dose-dependent manner after 12 days. Moreover, cell proliferation showed a similar pattern whether a given concentration of calcium ions was produced by calcium chloride or by release from MTA. CONCLUSIONS: In this ex-vivo study, the elution components such as calcium ions from MTA had higher proliferation ability of HDP cells than control and Dycal.

Adult↗
PubMed1987

Estimation of fetal weight in the third trimester by ultrasound.

A method to estimate the intrauterine fetal weight by use of ultrasound measurements of the fetal biparietal diameter (BPD) and the abdominal diameter (AD) is presented. From a consecutive series of single pregnancies the 238 pregnancies (3% of the hospital population) with ultrasound measurements obtained within 4 days before delivery were used in the estimation of birth weight. In addition, the estimated formula was applied on a test material consisting of 100 similarly selected pregnancies from the same hospital. To evaluate the expected selection effects, the birth weight for gestational age in the study group was compared with birth weight for gestational age in the total population. The weight could be estimated as 0.0351 X AD1.65 X BPD0.69 X exp(0.00196 X gestational age). Thus, the actual birth weight was within 83-120% of the estimated weight (95% prediction limits), with a residual coefficient of variation of about 9%. The gestational age could be omitted without major influence on the weight prediction. When applying the formula on the test material, 70% of the actual weights deviated less than 10% from the estimated fetal weight, but a tendency towards a slight overestimation of the weight for light for gestational age infants was found.

Birth Weight↗
PubMed1996

A respirometer with improved sensitivity for ready biodegradation testing.

In this paper we describe a respirometry system with improved sensitivity, that was used to test materials at concentrations down to 3 mg C/l. Data obtained with this system, operating under the conditions of the OECD ready biodegradability tests 301B, C, D and F, is presented and compared with CO2-production data obtained under 301B conditions in the Sealed Vessel Test. For simple materials, the shape of the curves, not easily seen with CO2 production or DOC removal data, is clearly biphasic with a sigmoidal first part-suggesting growth of the inoculum on the test materials. For a selection of rapidly and readily biodegradable materials, the removal of soluble carbon was complete at the end of the first, sigmoidal part of the biodegradation curve; It is speculated that the remainder of the curve probably represents the mineralisation of part of the biomass. The respirometer generated many hundred data points per degradation curve and Monod or exponential growth models were fitted and growth parameters were derived. Growth rates under ready test conditions were derived for six materials as follows: aniline mu = 0.31 h-1, ethanolamine mu = 0.13 h-1, 1,6-hexanediol mu = 0.05 h-1, pentaerythritol mu = 0.04 h-1, C12.8EO mu = 0.13 h-1 and commercial LAS mu = 0.05 h-1.

Biodegradation, Environmental↗
PubMed2003

Embryonic toxicity of a mancozeb containing fungicide formulation and Cu-sulphate in pheasant after individual or combined administration.

Cu-sulphate and a 80% mancozeb containing fungicide formulation (Dithane M-45) were studied in pheasants after administration as single compounds or in combination. The test materials were injected directly into the air-chamber of eggs on day 12 of the hatching period and evaulation was carried out on day 23 of incubation. The pheasant embryos were examined for the following: rate of embryo mortality, body mass, type of developmental anomalies, light microscopic examination. After the administration of copper-sulphate on day 12 of incubation, the average body weight of pheasant embryos significantly did not decrease as compared to the control. The embryonic mortality was 68%. After the administration of a mancozeb containing fungicide formulation (Dithane M-45) on day 12 of incubation, the average body weight of embryos did not decrease as compared to the control. The embryonic mortality was 50%. After the individual administration of pesticide, the incidence of developmental anomalies was very high. After the combined administration of copper-sulphate and the 80% mancozeb containing fungicide formulation (Dithane M-45) on day 12 of incubation the embryonic mortality markedly increased. The rate of embryo mortality was 93%. We did not find any degenerative change in the liver tissue in either the control group or the treated groups by light microscopic examination. In summary, it can be established that the simultaneous administration of Cu-sulphate and mancozeb containing fungicide formulation caused high toxicity compared with the individual toxicity of test materials.

Animals↗
PubMed2006

In vitro computer analysis of crown discolouration from commonly used endodontic sealers.

The aim of this study was to assess the degree of staining of tooth crowns by commonly used endodontic sealers using a computer analysis method. Crown discolouration by root canal sealers AH26, Endofill, Tubliseal, Zinc oxide eugenol (ZnOE), Apatite root canal sealer III as well as gutta-percha and Cavizol (a filling material containing ZnOE) were tested on extracted human premolar teeth. The roots of the teeth were resected 3 mm below the cemento-enamel junction. The pulp chambers were then cleaned and irrigated. The samples were divided into nine groups of five samples each and filled with test materials. Ten teeth were used as control groups: five positive (amalgam) and five negative (distilled water). The degree of tooth discolouration was analysed at 3, 6 and 9 months. The crown discolouration was assessed by computer analysis of digital images taken from the samples using the CIE Lab colour system. Statistical analysis was carried out using anova, repeated measure anova and Tukey's HSD tests. All sealers caused a degree of tooth discolouration, which increased with time. Endofill and ZnOE caused the greatest discolouration and Apatite root canal sealer III caused the least discolouration after 9 months. The most discolouration during the test periods occurred in the cervical third of the crown.

Analysis of Variance↗
PubMed2004

Effect of calcium hydroxide and chlorhexidine based gutta-percha points on gingival fibroblasts and epithelial tumor cells.

AIMS AND METHODS: The aim of the present study was to demonstrate the possible effect of different endodontic calcium hydroxide and chlorhexidine-based gutta-percha points, on two different human cell culture systems. Two different calcium hydroxide (Roeko, Langenau, Germany) and one chlorhexidine (Activ Point/Roeko, Langenau, Germany) gutta-percha points were tested with gingival fibroblasts and epithelial tumor cells over a period of six days (n = 12). Conventional gutta-percha points (VDW, Munich, Germany) and cells that were not exposed to any substances served as controls (n = 12). Study parameters included cell vitality, cell count, protein synthesis and cell proliferation. RESULTS: All tested materials induced cell growth specific alterations. Chlorhexidine-based gutta-percha points showed a significant lower protein synthesis with both, gingival fibroblasts (0.013 +/- 0.009 mg/ml) and epithelial tumor cells (0.07 +/- 0.039 mg/ml), when compared with the controls (p > 0.05). Protein synthesis increase of the epithelial tumor cells (0.581 +/- 0.013 mg/ml, control) was observed with the conventional gutta-percha points (0.688 +/- 0.078 mg/ml) and with both gutta-percha points containing different calcium hydroxide-based formulations (0.776 +/- 0.115 and 0.7 +/- 0.047 mg/ ml). CONCLUSIONS: Under the conditions of this study, chlorhexidine containing gutta-percha points showed the highest effect on cell growth inhibition. No significant differences were observed between the tested material and the two different cell culture types.

Adult↗
PubMed2004

Cytotoxicity of composite resins polymerized with different curing methods.

AIM: To compare the relative cytotoxicity of resin-based composite materials polymerized with three different curing methods on L 929 cells over a period of 1 week. METHODOLOGY: Ten discs of each material (Flowline, P 60 and Z 250) were cured from one side with either standard cure (Optilux 401), soft-start cure (Elipar Free Light) or fast cure (Hilux Ultra Plus). Then the samples were aged for 1, 2, 3, 5 and 7 days in Dulbecco's Modified Eagle Medium/Ham's F12 (DMEM/F12). After each ageing interval, cytotoxicity of the extracts to cultured fibroblasts (L 929) was measured by MTT assay. The degree of cytotoxicity for each sample was determined according to the reference value represented by the cells with a pure culture medium. Statistical significance was determined by one-way analysis of variance (anova), followed by the Student's Newman-Keuls test. RESULTS: Exposure of L 929 cells to the test materials resulted in a high survival fraction at 1 and 7 days. Flowline specimens, either cured with Optilux 401 or Elipar Free Light, had no toxic effect on the cells, whereas the other groups were moderately toxic on the 2-day interval. All experimental groups presented lower cell viability than the control at the 3- and 5-day intervals. CONCLUSIONS: The composite resins used in this study were cytotoxic after 48 h pre-incubation, but this toxicity disappeared after pre-incubation in a biological medium for 7 days. Curing did not have a significant effect on the cytotoxicity of the composite materials tested.

Analysis of Variance↗
PubMed1994

Toxicity testing of polymer materials for dialysis equipment: is there any need for in vivo testing?

In an earlier work, slightly more than 650 plastic materials, intended for use in medical devices, were tested with a battery of chemical, as well as in vitro and in vivo biological tests. An analysis showed that only a limited number of the tests used were actually necessary to obtain the same pass or fail decision as that obtained using the full test battery. This prompted us to prescreen all new materials with a small test battery consisting of the two most discriminating chemical tests and an in vitro cell growth inhibition test. The present work is a report of our findings after testing another 155 materials using this prescreen system. For each single one of the 155 tested materials the same decision on whether or not to use the material in the intended medical device would have been reached without any in vivo testing. In no single case in a total of 851 in vivo tests did an eluate that had passed the in vitro cell test give rise to a reaction in vivo. Thus, among the tests on living systems, the cell test alone seems to be sensitive enough to provide sufficient information. Nothing appears to be gained from the in vivo animal tests. However, some of the materials that passed the prescreening tests later failed in one or several of the chemical tests. Both nonspecific chemical tests and tests for specific molecules seem to detect undesirable levels of leachable substances not detected by the prescreening system. Therefore these tests should not be abandoned. Abandoning unnecessary in vivo testing, on the other hand, would save considerable costs.

Animals↗
PubMed2004

Evaluation of the roughness and mass loss of the flowable composites after simulated toothbrushing abrasion.

The purpose of this study was to measure mass loss and surface roughness changes of different brands of flowable resin composites after a simulated toothbrushing test. The null hypotheses were that there would be no differences in mass loss and no significant changes in surface roughness after this test and that there would be no correlation between the two variables. The tested materials were Aeliteflo (Bisco), Flow-It (Pentron), Flow-It LF (Pentron), Natural Flow (DFL) and Wave (SDI). Z100 (3M/ESPE) microhybrid and Silux Plus (3M/ESPE) microfilled resin composites were used as control materials. Twelve specimens (5 mm in diameter, 3 mm thick) of each material were prepared according to manufacturers' instructions. Toothbrushing abrasion was performed on all specimens from each of the materials using a simulator. The percentage mass loss and surface roughness were assessed before and after 100,000 brushstrokes, using a Sartorius analytical balance of 0.0001 g accuracy and a Hommel Tester T1000, respectively. The measurements of both properties were statistically compared by paired t-test and Tukey's test (p < 0.05). All materials presented a statistically significant mass loss comparing initial and final values, with the exception of Flow-It LF. However, no difference was revealed when comparing the mass loss of the different tested materials. All materials became rougher and Wave presented statistically higher roughness compared to the other resin composites. Flowable resin composites did not seem to be superior to the control groups, and they can be expected to wear by mass loss and to have an increased roughness of surface after toothbrushing action. The anticipated null hypotheses were partially accepted.

Composite Resins↗
PubMed2004

Immunoadjuvant potential of Asparagus racemosus aqueous extract in experimental system.

The immunoadjuvant potential of Asparagus racemosus (Willd.) Family (Liliaceae) aqueous root extract was evaluated in experimental animals immunized with diphtheria, tetanus, pertussis (DTP) vaccine. Immunostimulation was evaluated using serological and hematological parameters. Oral administration of test material at 100 mg/kg per day dose for 15 days resulted significant increase (P = 0.0052) in antibody titers to Bordtella pertussis as compared to untreated (control) animals. Immunized animals (treated and untreated) were challenged with B. pertussis 18323 strain and the animals were observed for 14 days. Results indicate that the treated animals did show significant increase in antibody titers as compared to untreated animals after challenge (P = 0.002). Immunoprotection against intra-cerebral challenge of live B. pertussis cells was evaluated based on degree of sickness, paralysis and subsequent death. Reduced mortality accompanied with overall improved health status was observed in treated animals after intra-cerebral challenge of B. pertussis indicating development of protective immune response. Present study indicates applications of test material as potential immunoadjuvant that also offers direct therapeutic benefits resulting in less morbidity and mortality.

Adjuvants, Immunologic↗