Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “RUBBER”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources
PubMed2006

Identification of poly(cis-1,4-Isoprene) degradation intermediates during growth of moderately thermophilic actinomycetes on rubber and cloning of a functional lcp homologue from Nocardia farcinica strain E1.

The enrichment and isolation of thermophilic bacteria capable of rubber [poly(cis-1,4-isoprene)] degradation revealed eight different strains exhibiting both currently known strategies used by rubber-degrading mesophilic bacteria. Taxonomic characterization of these isolates by 16S rRNA gene sequence analysis demonstrated closest relationships to Actinomadura nitritigenes, Nocardia farcinica, and Thermomonospora curvata. While strains related to N. farcinica exhibited adhesive growth as described for mycolic acid-containing actinomycetes belonging to the genus Gordonia, strains related to A. nitritigenes and T. curvata formed translucent halos on natural rubber latex agar as described for several mycelium-forming actinomycetes. For all strains, optimum growth rates were observed at 50 degrees C. The capability of rubber degradation was confirmed by mineralization experiments and by gel permeation chromatography (GPC). Intermediates resulting from early degradation steps were purified by preparative GPC, and their analysis by infrared spectroscopy revealed the occurrence of carbonyl carbon atoms. Staining with Schiff's reagent also revealed the presence of aldehyde groups in the intermediates. Bifunctional isoprenoid species terminated with a keto and aldehyde function were found by matrix-assisted laser desorption ionization-time-of-flight and electrospray ionization mass spectrometry analyses. Evidence was obtained that biodegradation of poly(cis-1,4-isoprene) is initiated by endocleavage, rather than by exocleavage. A gene (lcp) coding for a protein with high homology to Lcp (latex-clearing protein) from Streptomyces sp. strain K30 was identified in Nocardia farcinica E1. Streptomyces lividans TK23 expressing this Lcp homologue was able to cleave synthetic poly(cis-1,4-isoprene), confirming its involvement in initial polymer cleavage.

Actinomycetales↗
PubMed2005

Chain orientation in natural rubber, Part I: the inverse yielding effect.

Inhomogeneous deformations are observed in stretched natural rubber of different crosslink density; the conditions of observation, nucleation and propagation are given in the first part of the paper. In samples of low crosslink density these inhomogeneities recall necking observed in others materials and in glassy polymers when the materials are drawn above a critical draw ratio. The difference is that in natural rubbers, NR, they nucleate and propagate at constant stress during unloading. This phenomenon, called inverse yielding appears during recovery only if the samples have been drawn previously in the hardening domain. During necking propagation the stress is constant. The mechanical and crystallinity properties of samples with and without inverse yielding are studied as a function of draw ratio, crosslink density and temperature. In the second part of the paper this transition zone (neck) of thickness 2 mm is studied by WAXS at the synchrotron source. From the orientation of NR crystallites and from the orientation of the stearic acid (2%, present in this type of rubber) we conclude that the deformation in the neck follows the flow lines. From the local crystallinity of the NR crystallites one deduces the local draw ratio across this transition zone. We suggest that in all these rubbers, which present a plateau of the recovery stress strain curve, micronecking exists. This effect is discussed in the framework of the Flory theory.

Computer Simulation↗
PubMed1991

Surgical latex glove allergy: characterization of rubber protein allergens by immunoblotting.

Immunoblot analysis employing IgE antibodies derived from sera of 3 physicians and 2 nurses allergic to surgical latex gloves, disclosed 10 allergens in natural rubber sap. Nine of the 10 allergens were detected in ammoniated natural rubber latex, but only 4 allergens in a latex glove extract. The allergenic proteins had apparent molecular weights ranging from 14 to 70 kD. Allergens with molecular weights of 14 and 21 kD showed the most intense immunoblot reactions suggesting that these proteins could be the major allergens in the natural rubber. An 11-kD protein and a 26-kD protein were only seen in the glove extract, indicating that they could be modified rubber proteins formed during glove manufacture.

Adult↗
PubMed1997

Relevance of the use of rubber dam in microbiological sampling of carious dentine.

The aim of this study was to determine the role of rubber dam isolation and the influence of salivary contamination during cavity preparation on the collection of samples of dentine for microbiological examination. Cavities were prepared in 23 carious teeth. Access to caries was gained and a sample of soft, stained demineralized tissue was taken with a round bur. After removing the rubber dam each cavity was flooded with saliva and after thorough washing and drying a second dentine sample was taken. Cavity preparation was completed and the cavity flooded with saliva. After thorough washing and drying a final sample was taken. A data set from another study served as a control for bacterial contamination at the end of cavity preparation where a rubber dam remained in place throughout. There were no significant differences in the numbers of bacteria in dentine samples gathered with and without rubber dam, which implies that salivary contamination can be removed by thorough washing and drying of the cavity.

Adult↗
PubMed1994

Using rubber dams to boost quality, quantity of restorative services.

Rubber dam use for restorative dentistry is far too low. If practitioners realized rubber dam's advantages and increased treatment quality, its use would be irresistible. Few other dental procedures offer both an increase in operating speed and treatment quality. To save the most time, competent auxiliary staff should be taught to place rubber dams before the clinical procedure begins. (Additional information on rubber dam placement by auxiliary staff is available from Dr. Christensen.)

Dental Restoration, Permanent↗
PubMed1981

Oxidative hemoglobin breakdown induced by a rubber additive.

An antioxidant commonly present in black rubber, N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD) caused very rapid oxidation and denaturation of purified hemoglobin. In the red cells, the reaction resulted in the formation of Heinz bodies, a decrease in reduced glutathione concentration, and stimulation of the hexose monophosphate shunt. IPPD appears therefore to have the potential to induce hemolysis in glucose-6-phosphate dehydrogenase deficiency. It would be expected to be more potent than most redox reagents of this type. It does not require further metabolism to be reactive, and its reactivity is similar to that of phenylhydrazine. But in particular since both IPPD and its oxidized form can oxidize hemoglobin it can act catalytically, and at low concentrations is much more effective than phenylhydrazine. Oxidation of blood stored in contact with rubber seals containing IPPD has been observed. It is also possible that prolonged contact of susceptible individuals either with rubber containing IPPD or to IPPD itself during rubber manufacture could result in hemolysis.

Anemia, Hemolytic↗
PubMed1999

The "rubber band technique": a simple method for closing large skin defects.

Traditional methods of obtaining definitive soft-tissue cover in open wounds after high-energy trauma necessitate repeated surgical procedures and sophisticated soft-tissue reconstructions. A simple one-stage technique to treat skin loss in severe open fractures is described. The "rubber band technique" enables postoperative exposure and drainage of the fracture site. The wound closes gradually by facilitated mobilization of skin in response to continuous tension from the rubber band. This technique may prevent the need for additional procedures. Continuous drainage is achieved. When deep infection is suspected, removal of the elastic rubber band permits sufficient exposure of the deep tissues. The "rubber band technique" has proved to be a safe, simple, and efficient method for treating extensive soft-tissue loss in open fractures and after incisions for open reduction or fasciotomy.

Dermatologic Surgical Procedures↗
PubMedDate not supplied

Determination of moisture in rubber stoppers: effect of Karl Fischer oven temperatures.

Moisture released from rubber stoppers of pharmaceutical products may adversely affect product quality during storage. The objective of the current study was to identify an appropriate method to quantify free moisture in processed stoppers. The moisture content in stoppers is commonly determined by the Karl Fischer (KF) method. However, for the FM257/2 stoppers from Helvoet, our results suggest that the KF assay results are always lower than that from the gravimetric method and increase with the KF oven temperatures used. The systematic study presented in this manuscript shows that, although moisture results vary with respect to KF oven temperatures, reproducible results are obtained at fixed temperatures. Therefore, the observed variation can not be explained by the release of volatile chemicals from this rubber-affecting KF reagents. Furthermore, by extrapolating moisture results obtained with different thicknesses of rubber slabs to zero thickness, it was found that the diffusion barrier is also not a major source for the variation. It is hypothesized that the moisture in rubber stoppers can be free or bound. The KF method measures both free and bound moisture. As higher KF oven temperatures are used, more bound moisture is released and determined by the KF method. By deducting the bound moisture (measured by the KF method for samples dried at 100 degrees C for one week) from the sample moisture, the amount of free moisture (which is releasable) can be estimated. A KF oven temperature at 250 degrees C is recommended based on the accuracy and precision of the results. This method was validated by showing consistency with the gravimetric method for stoppers undergoing desorption at 25 degrees C and 0% relative humidity (equilibrated with P2O5). An example is also presented to show the application of this method.

Hot Temperature↗
PubMed2001

Cancer mortality in rubber tire workers in Poland.

The study aimed at assessing cancer risk in a cohort of workers employed in the rubber tire production. The cohort consisted of 17,747 workers (11,660 men and 6087 women) employed in a rubber tire plant for at least three months during the years 1950-1995. The cohort follow-up was completed on December 31, 1995. Deaths by causes were analyzed using standardized mortality ratio (SMR) calculated by the person-years method. The mortality pattern of the general population of Poland was used as the reference. The study indicated significantly lower total mortality in the cohort (men: SMR = 72; women: SMR = 62) as compared to the general population, which is an example of a well known "healthy worker effect". The number of deaths from malignant neoplasms was also lower than expected (men: SMR = 67; women: SMR = 64). Only in a very small sub-cohort of men involved in dosing and mixing of raw material for the production of rubber, an excess of total mortality (SMR = 104) and from all cancers (SMR = 115) was found. Mortality from all neoplasms was enhanced (SMR = 108) in the sub-cohort of women employed in the technical service work area. When analyzing individual cancer sites in men of the whole cohort or sub-cohorts, the observed number of deaths from cancers of the lip, tongue, pharynx, stomach, gallbladder, pancreas, peritoneum, articular cartilage, connective tissue, skin, testis, prostate, bladder, kidney, brain, as well as from Hodgkin's disease, multiple myeloma and leukemia was larger than the expected number. Among women the excess mortality was due to cancers of the large myeloma and leukemia. The SMR calculated for these sites were statistically insignificant. The cohort under study was "young" and thus relatively small numbers of deaths were recorded. The excess mortality, based quite frequently on single cases of selected cancer sites, cannot be regarded as a basis for final conclusions. Nevertheless, the fact that these observations are in agreement with the findings of other authors who carried out studies in the rubber industry of other countries justifies the need to follow-up this cohort in the future.

Adult↗
PubMed1992

Extending the use of rubber dam isolation: alternative procedures. Part I.

Most dentists are well aware of the value of the rubber dam in allowing technical excellence; however, few recognize the potential for protecting the dentist and staff against the ever-growing number of carriers of the hepatitis and human immunodeficiency viruses. The effectiveness of the rubber dam as an isolation barrier is dependent on the consistency of its application. Sporadic rubber dam application is therefore a weak link in an infection control program. This paper describes additional modified utilizations of rubber dam, uses that are generally not attempted with restrictive orthodox application methods. In addition, practical hints on other means of retention are offered, with the emphasis on nuisance-free and easy application.

Dental Implants↗
PubMed2005

[The rubber dam, a problem for the dentist or the patient?].

Although the advantages of rubber dam use are obvious and rubber dam use is established standard of care in many disciplines, its application in general dental practice is low. To assess whether a negative attitude of patients might be the case, 304 patients were asked by means of a questionnaire comments on their treatment under rubber dam. The majority of the patients experienced no hinder, excepted for rubber dam restricting the communication with the dental practitioner. Women experienced more often than men anxiety, whereas smokers more frequently experienced discomfort.

Adolescent↗
PubMed2006

[Medico-legal autopsy case of an infant suffering anaphylactic shock during dental treatment. Potential hazards in the use of a rubber-dam-sheet for infants].

We report a medico-legal autopsy of a 4-year-old girl without any history of allergies, who died following anaphylactic shock due to local anesthesia with lidocaine during dental treatment. The shock symptoms were overlooked due to a rubber-dam-sheet covering her face. The autopsy revealed laryngeal edema, secretory fluid filling the trachea, severe pulmonary congestion and edema. An immunohistochemical investigation showed numerous mast cells releasing histamine in lungs, and the fluids in the pulmonary alveoli and veins also showed positive staining. In addition, the plasma concentration of histamine in the heart blood showed a high value. From these findings, the cause of death was determined to be respiratory failure due to anaphylactic shock induced by lidocaine. In this case, her death was considered to be due to medical malpractice; adequate life support had not been performed, because anaphylactic shock was overlooked until the rubber-dam-sheet removed. In addition, due to two previous autopsy case reports that described infantile fatalities involved with the misusage of a rubber-dam-sheet for the patients under local anesthesia, we therefore recommend immediate improvements in rubber-dam-sheets and/or better applications of them in pediatric dentistry.

Anaphylaxis↗
PubMed1987

[Contact allergy to rubber, surgical and vinyl gloves].

Thirty-one patients with a contact allergy to gloves made from rubber or vinyl were investigated in a retrospective and prospective study. Sensitivity to rubber gloves used in the household and in industry occurred most frequently (64%), followed by surgical gloves (26%) and vinyl gloves (10%). Health service worker and housewife were the professions in which the allergy was most frequently present. The main sensitizers were found to be the rubber accelerators of the thiuram and carbamate group. A series of various gloves (household, surgical, vinyl) yielded extremely different results when tested epicutaneously on the rubber-sensitized individuals. Vinyl gloves, surgical gloves made from pure latex or surgical gloves with an inner plastic coating may alternatively be used by these patients.

Dermatitis, Contact↗
PubMed1987

[Achromatizing contact dermatitis caused by rubber sandals].

Depigmentation due to contact dermatitis, presents itself in most of the cases as a professional disease, and in only few reports it is shown to be caused by the use of personal items. From June 1982 to March 1983, six patients were observed with a symmetrically distributed contact dermatitis, located on the upper side of the feet, showing the marks of rubber sandal straps, know as "Hawaiian sandals". All patients were exposed to standard patch tests, containing 31 elements among which, there are seven substances that are related to the rubber manufacturing process, such as: potassium dichromate, mercaptobenzothiazole, diphenylguanidine, thiuram-rubber-mixture, colophony, p-phenylenediamine, hydroquinone. The interpretation of the patch tests was done after 48 an 72 hours, following the criteria that were established by the International Contact Dermatitis Research Group (ICORG). Five patients showed sensitiveness to at least, two of the suspected substances. Mercaptobenzothiazole and/or thiuram rubber mixture were the substances most frequently related to these cases of depigmentation. Two patients who had a positive patch test for the thiuram-mix, developed a depigmentation area on the site of the test after two weeks. Depigmentation produced by the thiuram-mix had not been related formerly and though our study it became evident that this substance can lead to it.

Adult↗
PubMedDate not supplied

Gas chromatographic-thermal energy analysis method for determination of volatile N-nitrosamines in baby bottle rubber nipples: collaborative study.

A collaborative study was conducted on the U.S. Food and Drug Administration (FDA) dichloromethane extraction method for determining volatile N-nitrosamines in baby bottle rubber nipples. Following dichloromethane extraction, N-nitrosamines were determined by gas chromatography-thermal energy analysis. Six pairs of blind duplicate rubber nipple samples representing 6 lots were analyzed by 11 collaborating laboratories. All samples were portions taken from equilibrated composites of cut-up rubber nipples obtained from manufacturers in the United States. Recoveries of the internal standard (N-nitrosodipropylamine) at approximately 20 ppb ranged from 10 to 120%. Reproducibility relative standard deviations (RSDx) were between 35 and 45% for N-nitrosamine levels from 10 to 20 ppb. However, when data from laboratories with recoveries less than 75% were excluded (this is now specified in the method), RSDx values were between 11 and 32% for N-nitrosamine levels from 6 to 26 ppb. Values were consistent with or better than those reported for other analytical techniques designed to quantitate trace contaminants at the low ppb level, e.g., aflatoxin in foods. The method has been adopted official first action for the quantitation of volatile N-nitrosamines in baby bottle rubber nipples.

Bottle Feeding↗
PubMed1983

Mutagenicity of rubber additives and curing fumes. Results from five short-term bioassays.

The mutagenicity of rubber additives and curing fumes from some rubber formulations were studied in five short-term tests: point mutations in Chinese hamster V79 cells, the induction of sister chromatid exchanges in Chinese hamster ovary cells, micronuclei in erythrocytes of Chinese hamster bone marrow, sex-linked recessive lethal mutations in Drosophila melanogaster, and reverse mutations in the Salmonella/microsome assay. When 46 rubber additives were tested with Salmonella, 15 compounds were mutagenic, 16 were negative, and 15 were negative with no observed toxicity. Only one negative response was obtained for the nine tested samples of curing fumes. Thiuram and dithiocarbamate additives and some curing fumes with mutagenic responses in Salmonella were the primary objects of study in the other four test systems. Although the results of these four tests did not completely parallel the Salmonella results, they indicate that the individual compounds and the curing fumes from different types of rubber formulations may involve genotoxic risks.

Air Pollutants, Occupational↗
PubMed1984

[Mutagenicity of organic rubber additives].

The DNA-damaging activities of organic rubber additives such as rubber vulcanizing agents, vulcanization accelerators and rubber anti-oxidants were investigated by the rec-assay using spores of Bacillus subtilis strains H 17 and M 45. For metabolic activation, 9,000 X g supernatant solutions of the liver homogenate of Sprague-Dawley male rats previously treated with aroclor 1,254 were used. Spore rec-assays were carried out at the dose of 1 mg/disk, and the ratio of inhibition zones for M 45 to that for H 17 was calculated. Samples showing a ratio of more than 1.2 were judged positive. In order to know the DNA-damaging capacity of positive samples, the dose-response curves were prepared by carrying out the assays at various doses, and minimal inhibition concentration (MIC) for H 17 and M 45 was obtained from these curves by extrapolation. Then indices of DNA damagenicity were calculated through division of the MIC obtained with H 17 by that with M 45. The 0.005 micrograms/disk of mitomycin C and at 4 micrograms/disk of Trp-P1 were used as positive control, and the 50 micrograms/disk of kanamycin as negative control. The results obtained are as follows: Among 20 tested samples, p-quinone dioxime, bis-morpholine disulfide used as rubber vulcanizing agents and hexamethylenetetramine, zinc butylxanthate used as vulcanization accelerators gave positive results. It was considered that the action of hexamethylenetetramine against DNA was due to the electrophilic state of this material. Furthermore, we supposed that DNA-damaging activity of p-quinone dioxime was concerned with free hydroxyl groups of this compound.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Naphthylamine↗
PubMed1982

[Selective membrane electrode for the determination of ammonia released from rubber caps of containers for parenteral solutions (author's transl)].

It is dealt with an ammonia-selective membrane electrode for the quantitative determination of volatile amines and ammonia released from rubber caps of containers for parenteral solutions. The optimal measurement parameters were determined. It was demonstrated that the electrode is well suited for ammonia determinations in the range of 10(-6) to 10(-1) mol/l. As this method requires but little time and yields accurate results, it will be helpful in laboratories with heavy routine workloads. Fifteen different caps based on natural rubber, chlorobutyl rubber or bromobutyl rubber were tested for their usefulness as packaging materials for drugs. According to the amounts of released ammonia, the caps were classified into three categories.

Ammonia↗