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PubMed1992

Solubilization of limulus test reactive material(s) from Candida cells by murine phagocytes.

Solubilization of limulus test reactive materials from Candida was examined in the presence or absence of phagocytic cells. Solubilized limulus test reactive materials (LTRM) were detected in culture supernatant, and hot water and sodium hydroxide extracts of the acetone dried cells of Candida parapsilosis. Suspensions of Candida cells also reacted with limulus test, and LTRM were released from the acetone dried cells by serum treatment. After treatment of the acetone dried cells with polymorphonuclear leucocytes (PMN) or macrophages (M phi), a significant amount of LTRM was solubilized. Significant amounts of LTRM were also released by PMN during treatment of live and growing C. parapsilosis. The reactivity of LTRM was completely inhibited by the addition of excess amount of purified (1----3)-beta-D-glucan, suggesting LTRM from Candida cells as described above would contain (1----3)-beta-D-glucan. These results suggested that LTRM during fungal infection would come from the extracellular water soluble polysaccharide fraction as well as the insoluble cell wall fraction solubilized by the action of phagocytes.

Animals↗

PubMed1985

A preliminary investigation into the nature of shock absorbency in synthetic sports materials.

Tests were conducted on three athletic shoe midsole materials and on three synthetic sports surfaces. All specimens were found to absorb energy when loaded. For a specific maximum load the amount of energy absorbed by each material was found to decrease as the load application rate increased. The materials exhibited different capacities to dissipate energy under the application of the same impulse. This may be a consideration for the injury protection afforded. The development of rheological models from the results of the tests aided an explanation of how force is resisted and energy absorbed by synthetic sports materials. Their shock absorbing properties were associated with the rheological elements of elasticity and viscosity.

Absorption↗

PubMed2004

Evaluation of bacterial adhesion of Streptococcus mutans on dental restorative materials.

Bacterial adhesion to the surface of composite resins and other dental restorative materials is an important parameter in the aetiology of secondary caries formation. The aim of the present study was to investigate the adhesion of a Streptococcus mutans strain (ATCC 25175) on the surface of different restorative materials. The test materials examined included three flowable composites (Filtek Flow, Tetric Flow, and Arabesk Flow), three microhybrid composites (Clearfil APX, Solitaire 2, and Z250), two glass-ionomers (Fuji IX, Fuji IX fast), a compomer (F2000), an ormocer (Admira), and a control reference material (tissue culture grade, surface treated polystyrene). The adhesion tests were carried out in 24-well plates. Quantitative turbidimetric measurements were finally performed in order to indirectly evaluate the amount of bacteria retained on the material surface after in vitro exposure to the bacteria suspension. Under these conditions, with the exception of the Admira ormocer and the Fuji IX fast glass ionomer, which were found to be more adhesive, all the other material surfaces showed a similar susceptibility to bacterial adhesion, exhibiting values not significantly different than the reference polystyrene control. Furthermore, the release of fluoride from some of the test surfaces did not appear capable to reduce early bacterial adhesion.

Adhesiveness↗

PubMedDate not supplied

Comparisons of the intraocular tissue distribution, pharmacokinetics, and safety of 125I-labeled full-length and Fab antibodies in rhesus monkeys following intravitreal administration.

Access of recombinant proteins to the retina following intravitreal administration is poorly understood. A study was conducted in male Rhesus monkeys (15 to 28 mo of age; 2.8-3.3 kg) in order to compare the intraocular tissue distribution, pharmacokinetics, and safety of 125Iodine (I)-labeled full-length humanized rhuMAb HER2 antibody (148 kD) and of 125I-labeled humanized rhuMAb vascular endothelial growth factor Fab antibody (48.3 kD) following bilateral bolus intravitreal injection on day 0 (5 animals/group). The dose administered to each eye was 25 microg (9-10 microCi) in 50 microl. Animals were euthanatized on day 0 (1 hr postdose) and on days 1, 4, 7, and 14. Safety assessment included direct ophthalmoscopy, intraocular pressure measurements, clinical observations, body weight, and hematology and clinical chemistry panels. Blood and vitreous samples were collected daily (blood only) and at necropsy for pharmacokinetics and analysis for antibodies to the test materials; the ocular tissue distribution of the test material was evaluated by microautoradiography. All animals completed the study. Microautoradiography demonstrated that the full-length antibody did not penetrate the inner limiting membrane of the retina at any of the time points examined. In contrast, the Fab antibody fragment diffused through the neural retina to the retinal pigment epithelial layer at the 1-hr time point and persisted in this location for up to 7 days. Systemic exposure to test material was low but variable: the highest plasma concentration of the full-length antibody was 20.3 ng/ml, whereas plasma concentrations for the Fab antibody remained below the limit of quantitation (i.e., <7.8 ng/ml). An immune response to the test material was not evident in either treatment group. The half-life in vitreous was 5.6 days for the full-length antibody and 3.2 days for the Fab antibody. The shorter intravitreal half-life of the Fab antibody is related to its smaller size and its significant diffusion through the retinal layers. The differences in pharmacokinetics and tissue distribution that are noted between the full-length and Fab antibodies in this study identify potential therapeutic approaches that may be exploited in specific disease conditions.

Animals↗

PubMed2003

Validation of EN ISO standard methods 6888 Part 1 and Part 2: 1999--enumeration of coagulase-positive staphylococci in foods.

The methods of European and International Organisations for Standardization for the enumeration of coagulase-positive staphylococci (CPS, Staphylococcus aureus and other species) described in EN ISO 6888 Part 1 and Part 2: 1999 were validated by order of the European Commission (Standards, Measurement and Testing Fourth Framework Programme Project SMT4-CT96-2098). EN ISO 6888-1 prescribes the use of Baird-Parker (BP) agar whereas EN ISO 6888-2 prescribes the use of Rabbit Plasma Fibrinogen Agar (RPFA). The objective was to determine the precision of each method in terms of repeatability (r) and reproducibility (R) using three different food types inoculated with various levels of S. aureus and a typical background flora. The results are intended for publication in the associated standards. Cheese, meat and dried egg powder were examined by 24 laboratories from 16 countries in Europe. Each participant received eight test materials per food type: blind duplicates at four inoculum levels (0, 10(3), 10(4) to 10(5), 10(5) to 10(6) cfu/g). In addition, two reference materials (RM) (capsules containing milk powder inoculated with S. aureus) were included in the study. All test materials were subjected to stringent homogeneity and stability testing before being used in the collaborative trial. Two statistical methods were used to calculate the precision parameters. Draft EN ISO 16140: 2000 method appeared more appropriate to the case of microbiological data than ISO 5725-2: 1994 method and was retained to calculate the precision data. Concerning EN ISO 6888-1, overall values for repeatability (r) when used with food test materials was r=log(10) 0.28 (expressed as an absolute difference between log(10)-transformed test results). For the reference materials, r=log(10) 0.19. Overall values for reproducibility (R) when used with food test materials were R=log(10) 0.43. For the reference materials, R=log(10) 0.39. Concerning EN ISO 6888-2, overall values for repeatability (r) when used with food test materials were r=log(10) 0.22. For the reference materials, r=log(10) 0.17. Overall values for reproducibility (R) when used with food test materials were R=log(10) 0.33. For the reference materials, R=log(10) 0.31. These results were presented to the ISO technical committee and to the Comité Européen de Normalisation (CEN). Both committees agreed to incorporate the precision data obtained with food materials as two amendments to EN ISO 6888-1 and -2, and to give an equal status to each part of the standard.

Bacteriological Techniques↗

PubMed1999

Comparison of test methods and early toxicity characterization for five dispersants.

The acute toxicities of a commercial dispersant (Corexit 9527) and four experimental dispersant formulations were evaluated using the 96-h mysid (Mysidopsis bahia) test and two rapid screening tests, Microtox and the Mysid IQ Toxicity Test. During 96-h toxicity tests, survival observations were recorded at 3, 6, 9, 12, and 24 h to document mortalities from short-term exposures more consistent with field exposure times and more approximate to exposure times used in Microtox and the Mysid IQ Toxicity Test. At nominal concentrations (6.25 and 12.5 mg/liter) and exposure times (3-24 h) near the upper range of predicted field conditions, mysid mortalities were </=5% for all test materials. Microtox and Mysid IQ Toxicity Test were evaluated for their ability to differentiate test materials compared with that of the 96-h mysid test. Dispersant formulations were ranked by relative toxicities based on LC50 or EC50 values and ranks compared among test methods. Microtox ranked the test materials similar to the 96-h mysid test. Ranks from the Mysid IQ Toxicity Test were dissimilar to those of the other tests. Early mortality observations during 96-h tests did not provide a better basis for comparing results of the rapid screening tests.

Animals↗

PubMedDate not supplied

Policy statement on materials for testing glucose in the urine. The Committee on Materials and Therapeutic Agents, American Diabetes Association.

Semiquantitative methods for measurement of glucose in the urine are useful for monitoring glucose homeostasis in subjects with diabetes mellitus where quantitative blood and urine glucose measurements are not available. The use of a "plus" scale for glucose measurement is confusing because the same plus values are assigned to different quantities of glucose with different methods. The two-drop Clinitest method is the most quantifiable and readable test for urine sugar, particularly if there is high sugar spill. Therefore, it is the most useful method for monitoring insulin-dependent juvenile diabetes. Its major disadvantages are its potential toxicity, the cumbersome methodology, the cost, and the possibility of interference from other reducing substances. The enzyme "dipstick" methods are most sensitive for detecting the presence of glucose. Among the available "dipstick" methods, Diastix is the most quantifiable and readable. These methods are inhibited by the presence of ketones and a number of other substances. Tes-Tape is the least expensive and, where there are inhibiting substances, the most useful, because it can be read at the liquid front where the glucose reaction is chromatographically separated. Clinistix and Chemstrip are essentially screening methods for the presence of glucose and not useful for quantification. Basing therapy on these and other plus values is irrational and should be discontinued.

False Negative Reactions↗

PubMed1998

Marginal adaptation and retention of a glass-ionomer, resin-modified glass-ionomers and a polyacid-modified resin composite in cervical Class-V lesions.

OBJECTIVES: An 18-month follow-up clinical trial of one conventional glass-ionomer (HIFI Master Palette), three resin-modified glass-ionomers (Fuji II LC, Vitremer, 3M Exp. 155) and one polyacid-modified resin composite (Dyract) was conducted to evaluate their clinical effectiveness in Class-V cervical lesions. In addition, the interface between dentin and two resin-modified glass-ionomers and one polyacid-modified resin composite was examined by scanning electron microscopy (SEM). METHODS: After evaluation of the restorations immediately following placement (baseline), all patients were subjected to a strict recall schedule with controls at 6, 12 and 18 months. The clinical effectiveness was recorded in terms of retention and marginal integrity, clinical microleakage, caries recurrence, and tooth vitality. A chi 2-test (p < 0.05) was used to test for significant differences between materials. In case of restoration loss or special defects, a replica was made to examine the surface texture and restoration margins by SEM. In vitro, the interface was examined by SEM after an argon-ion-beam etching technique was used to enhance surface relief and disclose interfacial substructures. RESULTS: Retention appeared to be good for all the materials tested. Marginal discrepancies were localized at the incisal enamel and/or the cervical dentin margin, except for the polyacid-modified resin composite that showed most of the defects at the incisal enamel margin. None of the systems could guarantee margins free of microleakage for a long time. In vitro, the type of dentin pre-treatment defines to a great extent the morphology of the resultant interface between dentin and the restorative material tested. SIGNIFICANCE: In this clinical study, the retention rate of the tested materials was good and even excellent for some products. Perfect marginal adaptation deteriorated too fast. The marginal adaptation of the polyacid-modified resin composite at the enamel site would probably have been better by the use of selective enamel or total acid etching. Marginal sealing remains a problem. Future research should concentrate on improving the marginal adaptation and sealing capacities before a broader clinical use can be advocated.

Acrylic Resins↗

PubMed1997

Culturally valid assessment tools: northern Sotho translation of the Peabody Picture Vocabulary Test-Revised.

There is currently a great demand for service provision for the African language speakers in South Africa. The difficulties associated with assessing speakers in the absence of assessment tools in the indigenous languages is, therefore, also a pertinent concern. Within the current socio-economic climate in South Africa where test translation and adaptation is often cited as a more viable option than that of developing new tests, very few guidelines exist for the development or adaptation of valid assessment tools for culturally and linguistically diverse population groups. This article is aimed at describing the process which took place when existing English test material, in this instance, The Peabody Picture Vocabulary Test--Revised (PPVT-R) (Dunn & Dunn, 1981) was translated and culturally adapted for the Northern Sotho population in Pretoria and surrounding areas. The findings of the research include practical examples of methodological considerations which should be taken into account while translating and undertaking cultural adaptation of test material. The newly adapted test material was also applied to a sample of 152 North-Sotho speaking pupils in the study area and the test results are discussed.

Black or African American↗

PubMedDate not supplied

The 21-day human cumulative irritation test can be reduced to 14 days without loss of sensitivity.

The 21-day cumulative irritation test for assessing the irritancy of topical products and chemicals is a venerable procedure that appears to have become the gold standard for manufacturers. Berger and Bowman in 1982 (1) showed that reducing the exposure to 14 days was less traumatic to the volunteers, less costly, less arduous, and did not affect reliability or the capacity to place the test agents in the proper rank order of irritancy. In the current study we compared (a) the 21-day cumulative irritation test, (b) the 14-day cumulative irritation test, and (c) the 14-day test with every-other-day patching. Additionally, ten-day, seven-day and four-day data from the 21-day test were compared. Forty-one subjects completed this study of six test materials. Two sets of patches were applied to each subject' lower back. One set had 21 consecutive applications of the test articles. The second set was applied, and removal of the test articles occurred Monday, Wednesday, and Friday for 14 days. The 21-day test fully differentiated the test materials from each other. Using only the first 14 days of the 21-day test also fully differentiated the test materials. Every-other-day patching rank ordered the test materials the same as the everyday patching, but full differentiation of the test materials was not obtained. We conclude that the 14-day cumulative irritancy test is as reliable and sensitive as the 21-day test, along with the obvious advantages in time, cost, and minimization of trauma to the test subjects.

Administration, Topical↗

PubMed2001

Demineralization of enamel in relation to the fluoride release of materials.

PURPOSE: To examine the reduction in enamel demineralization provided by fluoride release from a conventional glass-ionomer, a resin-modified glass-ionomer and an experimental fluoride-releasing resin-based composite compared to a conventional resin-based composite control, and to correlate the level of fluoride release with demineralization. MATERIALS AND METHODS: Enamel surfaces of extracted human incisors had a 0.4 mm thick layer of the specified test material carefully placed in a band across the mid-facial enamel to simulate a cement layer beneath an orthodontic bracket. The top surface of the test material was covered with nail varnish, leaving only the edges of the material exposed to release fluoride. The teeth were additionally covered with nail varnish to within 1 mm of the test material. Each group of teeth was placed into separate volumes of unstirred demineralizing solution at a pH of 4.7 for 4 days. The specimens were sectioned and examined by polarized light microscopy. Lesion areas were measured at distances from 100-800 microm away from the test material. Fluoride release for the test materials was measured for periods up to 5 months. RESULTS: All of the fluoride-releasing materials demonstrated a statistically significant (P< 0.05) degree of protection of enamel from demineralization compared to the non-fluoride control material. The degree of protection was greatest near the material, but lesion areas increased with distance in an inverse relationship to the amount of fluoride release. Lesions were displaced from the region near the materials and the mean displacement was directly related to amount of fluoride release. The mean lesion areas for each distance decreased with the logarithm of the cumulative fluoride release.

Acetates↗

PubMed1994

Shock-absorbing behavior of four processed soft denture liners.

The cushioning effect of soft denture liners was evaluated with the use of a free drop test with an accelerometer. The materials tested included SuperSoft, Kurepeet-Dough, Molteno Soft, and Molloplast-B brands. All materials were found to reduce the impact force when compared with denture base resin. A 2.4 mm layer of soft denture material demonstrated good shock absorption. The Molloplast-B and Molteno Soft materials showed excellent shock absorption. When the soft denture liner was stored in distilled water for 180 days, the damping effect recorded for all materials tested was increased. The aging of all materials also affected the cushioning effect.

Absorption↗

PubMed2007

Comparison of the clinical and preclinical biocompatibility testing of dental materials: are the ISO usage tests meaningful?

International Organization for Standardization (ISO 10993 and 7405) guidelines recommends the preclinical screening of dental materials using non-human primates. The literature contains no comparisons of responses to dental materials. To test the accuracy of preclinical screening tests for predicting human clinical responses, 106 class V pulp exposed cavities were prepared in human and non-human primate teeth. Teeth were restored with calcium hydroxide and amalgam, zinc oxide eugenol or resin-modified glass ionomer. Teeth were extracted after 10-163 days and prepared for histological analysis. Pulp cell numbers were compared and their reactionary dentin activity measured in response to cavity preparation. Pulp inflammatory activity was categorized according to ISO standards. There were no statistically significant differences between human and non-human primate teeth in terms of pulp reactions to dental materials. The use of non-human primates for preclinical biocompatibility investigation provided an accurate method of evaluating clinical responses to dental materials.

Adolescent↗

PubMed1985

Masticatory ability in patients with removable dentures. A clinical study of masticatory efficiency, subjective experience of masticatory performance and dietary intake.

One of the functions of the masticatory system is to grind the food, salivate and prepare it for swallowing. Individuals who have lost many teeth or wear removable dentures, both complete and partial, find it more difficult to grind food i.e. they suffer from impaired masticatory efficiency (ME). Some of these subjects have to avoid food-stuffs which are hard and difficult to chew. This could influence the social well-being and may eventually lead to an increased risk of malnutrition. Many different methods have been used to evaluate ME. In most of them the degree to which the masticated food or test material was broken down was measured by fractionating the particles in a sieve system. However, one of the purposes of chewing the food is to enlarge the surface area to be exposed to the digestive juices. A few authors have applied this idea and have calculated ME using the summarized area of the masticated test material. This is physiologically a more correct method. ME was investigated in 19 complete denture wearers who were fitted with new dentures. The subjects were tested twice with the old dentures and 5 times with the new ones. The last test took place about 18 months after insertion of the new dentures. The test material was gelatin hardened with formalin. The breakdown of test material was calculated by fractionating it in a sieve system. ME was also evaluated in two other groups, 43 complete denture wearers, who were in need of new dentures, and 19 subjects who were in need of RPDs in the lower jaw. In these two studies ME was evaluated in two ways. Firstly the summarized area of masticated gelatin particles was calculated and used as a measure of ME. Secondly almonds were used as test material and the breakdown was calculated by fractionating in a sieve system. The subjects were tested on three occasions, before prosthetic treatment and about one and four months after insertion of the dentures. On the first and last occasions the subjective experience of masticatory performance was assessed as well as the dietary intake. The results revealed no systematic change in ME when the 19 subjects were fitted with new complete dentures and when the breakdown of the test material was evaluated by fractionating it in a sieve system.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed2000

Amendment of various device regulations to reflect current American Society for Testing and Material citations. Food and Drug Administration, HHS. Direct final rule.

The Food and Drug Administration (FDA) is amending certain references in various medical device regulations. The amendments update the references in those regulations to various standards of the American Society for Testing and Materials (ASTM) to reflect the current standards designations. Elsewhere in this issue of the Federal Register, FDA is publishing a companion proposed rule, under FDA's usual procedures for notice-and-comment, to provide a procedural framework to finalize the rule in the event that the agency receives any significant adverse comment and withdraws the direct final rule.

Equipment and Supplies↗

PubMed1999

Thirteen-week subchronic rat inhalation toxicity study with a recovery phase of trivalent chromium compounds, chromic oxide, and basic chromium sulfate.

The toxicity of trivalent chromium compounds; chromic oxide and basic chromium sulfate, was investigated in rats in a 13-week nose-only inhalation study that included a 13-week recovery period. Nose-only exposures to insoluble chromic oxide dust at 4.4, 15, or 44 mg/m3 or soluble basic chromium sulfate dust at 17, 54, or 168 mg/m3 (trivalent chromium equivalent concentrations of 3, 10, and 30 mg/m3) were carried out for 6 h/day, 5 days/week. No compound-related mortality occurred. General toxic effects, only observed with high-exposure levels of basic chromium sulfate, included sporadic signs of labored breathing and depressed body weights. No apparent compound-related effects were noted for sperm motility or morphology, for any concentration of either test material. Bronchoalveolar lavage fluid evaluations showed test material in mononuclear cells with chromic oxide and increased neutrophils, protein, lactic dehydrogenase and cellular debris with basic chromium sulfate. The principle effects for both materials were primarily to the respiratory tract. Chromic oxide caused pathological changes in the bronchial and mediastinal lymphatic tissue and lungs, consisting of the presence of pigment-laden macrophages, lymphoid and septal hyperplasia, and interstitial inflammation similar to that observed with other inert dusts. Basic chromium sulfate produced more severe and widespread effects in the nasal cavity, larynx, lungs, and mediastinal lymph node. Effects were characterized by accumulation of foreign material, infiltration of alveolar macrophages, septal cell hyperplasia, and granulomatous and chronic inflammation. Pigment was still present in chromic oxide and, to a lesser extent, in basic chromium sulfate-treated animals after the 13-week recovery period, with partial recovery of the pathological lesions. A NOAEL was not established for either test material, but 4.4 mg/m3 was thought to be near the NOAEL level for subchronic exposure to chromic oxide. The results of this study indicate significant differences in toxicity to the respiratory tract between trivalent chromium compounds chromic oxide and basic chromium sulfate. These are likely related to differences in acidity and water solubility, rather than chromium concentration per se. This conclusion is substantiated by the lack of effect on other internal organs.

Administration, Inhalation↗

PubMed1984

Comparison of commercial beef extracts and similar materials for recovering viruses from environmental samples.

Microbiological- and food-grade beef extracts, protein hydrolytic, enzymatic and autolytic digestion products, and whole protein materials were examined for their potential effectiveness for eluting adsorbed enteroviruses from membrane filters with observed efficiencies ranging from less than 1 to 69%. Concentration of enteroviruses from solutions of these protein and protein-derived products by organic flocculation ranged in efficiency from 2 to 125%. Both elution and concentration were dependent upon virus type, as well as nature, source, and production lot of the material being tested. Determining the efficiency of virus concentration was complicated by virus aggregation and apparent virus inactivation by low pH. Effectiveness of concentrating viruses by organic flocculation from solutions prepared with the various test materials seemed independent of the amount of precipitate produced during the flocculation procedure. Quality assurance tests were proposed by which solutions prepared from beef extracts, whole protein, and protein-derived materials could be evaluated for use in eluting adsorbed viruses from membrane filters and for concentrating viruses by organic flocculation. Food-grade beef extract seemed equal to microbiological-grade beef extract in terms of both virus elution and concentration. Several of the nonbeef extract materials evaluated were as effective as beef extract for virus concentration, but were less effective for virus elution.

Adsorption↗

PubMed1975

Biological evaluation of polymers. I. Poly(methyl methacylate).

A series of poly(methyl methacrylate) formulations differing widely in chemical and physical properties was employed for the evaluation of primary screening methods for the assessment of acute toxicity. Materials and USP extracts of materials were tested in parallel. Tissue culture, hemolysis, intradermal irritation, systemic toxicity, muscle implant and histopathologic responses were determined for each of 27 formulations. A determination of the nonvolatile methanol extractable components was carried out on each formulation. The formulations varied with respect to percent, w/w, methyl methacrylate, N,N-dimethyl-p-toluidine, stannous octoate, 3, 4-diamino-toluene and, also, with respect to curing conditions. Volatile components, primarily methyl methacrylate, of three selected formulations were determined quantitatively by vacuum distillation and mass spectrographic analysis. Statistical analysis of the primary data indicated a significant correlation of residue weight (methanol extractable) with hemolytic activity (r = 0.93) and with the cumulative biological response (r = 0.9). Multiple linear regression analysis of residue weights with hemolysis and intradermal irriation responses gave the highest overall correlation (r = 0.96). Hemolytic activity and tissue culture responses were significantly correlated (r = 0.87). It was concluded that the observed variation of biological test results reflected significant differences in the toxicity of the test materials. The poly(methyl methacrylate) series examined was relatively low in toxicity and the biological tests examined, particularly the in vitro tests, were found to be responsive to formulation and curing conditions which indicated their suitability for primary toxicity screening.

Animals↗