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 19 recordsLinked to original sources
PubMed2000

Exposure to rubber fume and rubber process dust in the general rubber goods, tyre manufacturing and retread industries.

This study assesses the current patterns and levels of exposure to rubber fume and rubber process dust in the British rubber industry and compares and contrasts the data obtained from the general rubber goods (GRG), retread tire (RT) and new tire (NT) sectors. A total of 179 rubber companies were visited and data were obtained from 52 general rubber goods, 29 retread tire and 7 new tire manufacturers. The survey was conducted using a questionnaire and included a walk-through inspection of the workplace to assess the extent of use of control measures and the nature of work practices being employed. The most recent (predominantly 1995-97) exposure monitoring data for rubber fume and rubber process dust were obtained from these companies; no additional sampling was conducted for the purpose of this study. In addition to the assessment of exposure data, evaluation of occupational hygiene reports for the quality of information and advice was also carried out.A comparison of the median exposures for processes showed that the order of exposure to rubber fume (E, in mg m(-3)) is: E(moulding) (0.40) approximately E(extrusion) (0.33)>E(milling) (0.18) for GRG; E(press) (0. 32)>E(extrusion) (0.19)>E(autoclave) (0.10) for RT; and E(press) (0. 22) approximately E(all other) (0.22) for NT. The order of exposure to rubber fume between sectors was E(GRG) (0.40)>E(RT) (0.32)>E(NT) (0.22). Median exposures to rubber process dust in the GRG was E(weighing) (4.2)>>E(mixing) (1.2) approximately E(milling) (0.8) approximately E(extrusion) (0.8) and no significant difference (P=0. 31) between GRG and NT sectors. The findings compare well with the study carried out in the Netherlands [Kromhout et al. (1994), Annals of Occupational Hygiene 38(1), 3-22], and it is suggested that the factors governing the significant differences noted between the three sectors relate principally to the production and task functions and also to the extent of controls employed. Evaluation of occupational hygiene reports indicated a number of shortcomings including lack of suitable and sufficient information with regard to sampling and analytical methods in use, poor sampling strategy, lack of appreciation regarding true rubber process dust, and a poor understanding of the principles of control for substances assigned maximum exposure limits.

Air Pollutants, Occupational↗
PubMed1985

Sensitivity to rubber. Study with rubber mixes and individual rubber chemicals.

During a 3-year period 3332 patients were patch tested with ICDRG standard series including 4 rubber mixes. Additional tests were performed with individual rubber chemicals and suspected solid rubber products. Rubber sensitivity was detected in 158 (4.7%) patients. Thiuram mix caused most of the positive reactions (73) followed by carba mix (51), PPD mix (40) and mercapto mix (19). From the individual rubber chemicals TMTM, TETD and IPPD caused allergic reactions most frequently. Rubber mixes, especially thiuram and PPD mix appeared to be better screening agents than any individual chemical to detect rubber allergy. However, MBT is recommended to be tested separately. Carba mix caused several irritant reactions. Three immediate type rubber reactions were seen. Gloves were the most common individual sources of rubber sensitivity.

Dermatitis, Contact↗
PubMed1989

Rubber elongation factor from Hevea brasiliensis. Identification, characterization, and role in rubber biosynthesis.

The presence of a protein, rubber elongation factor (REF), which is tightly bound to serum-free rubber particles purified from Hevea brasiliensis latex, is necessary for prenyltransferases from a number of sources to add multiple cis-isoprene units to rubber molecules. These prenyltransferases show normal farnesyl pyrophosphate synthase activity (two trans additions of isopentenyl pyrophosphate to dimethylallyl pyrophosphate) in the absence of REF bound to rubber particles. REF bound to rubber molecules can be highly purified from all other proteins in whole latex by treatment of rubber particles with low concentrations of detergent. Treatment of rubber particles with trypsin which hydrolyzes bound REF, removal of REF with high concentrations of various detergents, or treatment of whole latex with polyclonal antibodies specific for REF all prevent prenyltransferase from adding [14C]isopentenyl pyrophosphate to rubber molecules. However, we have not been successful using detergent-solubilized REF in the reconstitution of in vitro rubber biosynthesis with either REF-depleted rubber particles or allylic pyrophosphate primers. REF has a molecular mass of 14,600 Da and is associated specifically with rubber particles in whole latex. It makes up between 10-60% of the total protein in whole latex but is absent in C-serum, the supernatant fluid obtained when rubber particles are removed by centrifugation. The amount of REF in whole latex is proportional to the rubber content. Based on a number average molecular mass of 500,000 Da for rubber and the content of rubber and REF in whole latex or serum-free rubber particles, the stoichiometry of REF molecules to rubber molecules is 1:1 in both cases. There is sufficient REF to form a monomolecular protein layer coating large rubber particles (700-1,000 nm). In the electron microscope, serum-free rubber particle preparations contain particles with diameters from 800 to as small as 10 nm. In the presence of 1% sodium dodecyl sulfate no particles smaller than 100 nm are observed. We suggest that the smaller particles may be mainly composed of REF molecules.

Allergens↗
PubMed2000

Identification of natural rubber and characterization of rubber biosynthetic activity in fig tree.

Natural rubber was extracted from the fig tree (Ficus carica) cultivated in Korea as part of a survey of rubber producing plants. Fourier transform infrared and (13)C nuclear magnetic resonance analysis of samples prepared by successive extraction with acetone and benzene confirmed that the benzene-soluble residues are natural rubber, cis-1,4-polyisoprene. The rubber content in the latex of fig tree was about 4%, whereas the rubber content in the bark, leaf, and fruit was 0.3%, 0.1%, and 0.1%, respectively. Gel-permeation chromatography revealed that the molecular size of the natural rubber from fig tree is about 190 kD. Similar to rubber tree (Hevea brasiliensis) and guayule (Parthenium argentatum Gray), rubber biosynthesis in fig tree is tightly associated with rubber particles. The rubber transferase in rubber particles exhibited a higher affinity for farnesyl pyrophosphate than for isopentenyl pyrophosphate, with apparent K(m) values of 2.8 and 228 microM, respectively. Examination of latex serum from fig tree by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed major proteins of 25 and 48 kD in size, and several proteins with molecular mass below 20 and above 100 kD. Partial N-terminal amino acid sequencing and immunochemical analyses revealed that the 25- and 48-kD proteins were novel and not related to any other suggested rubber transferases. The effect of EDTA and Mg(2+) ion on in vitro rubber biosynthesis in fig tree and rubber tree suggested that divalent metal ion present in the latex serum is an important factor in determining the different rubber biosynthetic activities in fig tree and rubber tree.

Cations, Divalent↗
PubMed1986

Rubber production in guayule: determination of rubber producing potential.

Optimum conditions for the rapid, efficient, nondestructive determination of rubber producing potential in guayule (Parthenium argentatum) were established. The rubber producing potential may be defined as the ability of the plant material to synthesize rubber from a precursor under specified conditions. To achieve this, stem slices taken from the first 5 centimeters of branches were incubated with [(14)C]acetate as precursor in 0.1 molar phosphate buffer (pH 6.5) at 26 degrees C for 16 hours in the light. The (14)C from labeled acetate and acetyl coenzymeA were efficiently incorporated into rubber whereas the (14)C from both mevalonic acid (MVA) and isopentenylpyrophosphate (IPP) were poorly incorporated. Incorporation of 68.6% of the (14)C from labeled IPP into the acetone extractable material suggests that most of the IPP was channeled down the lower terpenoid branch of the polyisoprene biosynthetic pathway. The incorporation of (14)C from labeled acetate into rubber was most efficient at temperatures between 20 and 25 degrees C. The rubber producing potential was also found to be dependent on light intensity. The roots which represent about one-third of the plant biomass not only had the highest rubber producing potential but also contained the highest amount of rubber (7.6%), indicating that the root system could be a major source of rubber. The mature stem bark also had a high rubber content and rubber producing potential, whereas the young stem had a low rubber content and a lower potential for producing rubber. The leaves showed little potential to incorporate labeled acetate into rubber and no more than 0.5% rubber was found in guayule leaves.

Journal Article↗
PubMed1993

Seasonal Variations in Rubber Biosynthesis, 3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase, and Rubber Transferase Activities in Parthenium argentatum in the Chihuahuan Desert.

The rubber content and the activities of enzymes in the polyisoprenoid pathway in Parthenium argentatum (guayule) were examined throughout the growing season in field plots in the Chihuahuan Desert. The rubber content of the plants was low in July and August and slowly increased until October. From October to December there was a rapid increase in rubber formation (per plant) from 589.0 mg to 4438.0 mg. The percentage of rubber in the plants increased from 0.7% (mg/g dry weight) in August and 1.27% in October to 5.5% in December. The rapid increase in rubber formation may result from exposing the plants to low temperatures of 5 to 7[deg]C. The activity of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) was 21.1 nmol mevalonic acid (MVA) h-1 g-1 fresh weight in the bark of the lower stems in June during seedling growth and decreased to 5.1 nmol MVA h-1g-1 fresh weight in July and 2.9 nmol MVA h-1 g-1 fresh weight in September. From October to December, the activity increased from 5.0 to 29.9 nmol MVA h-1 g-1 fresh weight. The activity of rubber transferase was 65.5 nmol isopentenyl pyrophosphate (IPP) h-1 g-1fresh weight in the bark in September and increased to 357.5 nmol IPP h-1 g-1 fresh weight in December. The rapid increase in the activities of HMGR and rubber transferase coincided with the rapid increase in rubber formation. The activities of MVA kinase and IPP isomerase did not significantly increase in the fall and winter. A tomato HMGR-1 cDNA probe containing a highly conserved C-terminal region of HMGR genes hybridized at low stringency with several bands on blots of HindIII-digested genomic DNA from guayule. In northern blots with the HMGR-1 cDNA probe at low stringency, HMGR mRNA was high in June and November, corresponding to periods of high HMGR activity during seedling growth and rapid increase in rubber formation. The seasonal variations in rubber formation and HMGR mRNA, HMGR activity, and rubber transferase activity may be due to low temperature stimulation in the fall and winter months.

Journal Article↗
PubMed1999

Rubber particles from four different species, examined by transmission electron microscopy and electron-paramagnetic-resonance spin labeling, are found to consist of a homogeneous rubber core enclosed by a contiguous, monolayer biomembrane

The physical characteristics of rubber particles from the four rubber (cis-1,4-polyisoprene) producing species Euphorbia lactiflua Phil., Ficus elastica Roxb., Hevea brasiliensis Mull. Arg., and Parthenium argentatum Gray, were investigated using transmission electron microscopy (TEM) and electron-paramagnetic-resonance (EPR) spin labeling spectroscopy. Transmission electron microscopy showed the rubber particles to be composed of a spherical, homogeneous, core of rubber enclosed by a contiguous, electron-dense, single-track surface layer. The biochemical composition of the surface layer and its single-track TEM suggested that a monolayer biomembrane was the surface structure most compatible with the hydrophobic rubber core. The EPR spectra for a series of positional isomers of doxyl stearic acid, used to label the surface layer of the rubber particles, exhibited flexibility gradients and evidence for lipid-protein interactions for all four rubber particle types that is consistent with a biomembrane-like surface. The EPR spectra confirmed that the surface biomembrane is a monolayer. Thus, rubber particles appear similar to oil bodies in their basic architecture. The EPR spectra also provided information on protein location and degree of biomembrane penetration that correlated with the known properties of the rubber-particle-bound proteins. The monolayer biomembrane serves as an interface between the hydrophobic rubber interior and the aqueous cytosol and prevents aggregation of the particles. An unexpected observation for the probes in pure polyisoprene was evidence of an intrinsic flexibility gradient associated with the stearic acid molecule itself.

Journal Article↗
PubMed2001

Anaerobic desulfurization of ground rubber with the thermophilic archaeon Pyrococcus furiosus--a new method for rubber recycling.

The anaerobic sulfur-reducing archaeon Pyrococcus furiosus was investigated regarding its capacity to desulfurize rubber material. The microorganism's sensitivity towards common rubber elastomers and additives was tested and several were shown to be toxic to P. furiosus. The microorganism was shown to utilize sulfur in vulcanized natural rubber and an increase in cell density was obtained when cultivated in the presence of spent tire rubber. Ethanol-leached cryo-ground tire rubber treated with P. furiosus for 10 days was vulcanized together with virgin rubber material (15% w/w) and the mechanical properties of the resulting material were determined. The increase in the stress at break value and the decrease in swell ratio and stress relaxation rate obtained for material containing microbially treated rubber (compared to untreated material) show the positive effects of microbial desulfurization on rubber.

Biotechnology↗
PubMed1981

Structural deterioration of prosthetic oesophageal tubes: an in vitro comparison of latex rubber and silicone rubber tubes.

In a series of 100 patients with carcinoma of the oesophagus or cardia undergoing palliative intubation at endoscopy using a latex rubber or a silicone rubber tube 2 cases of tube fragmentation were encountered and are described. The effects of hydrochloric acid, bile and irradiation on the tubes have been studied in vitro. After incubation in hydrochloric acid (0.1 mol/l), the breaking force of latex rubber tubes fell by 31 per cent (48 N) (but did not change significantly for silicone rubber tubes. The addition of bile to the hydrochloric acid (0.1 mol/l) did not further influence the breaking force of either type of tube. Megavoltage irradiation with 7500 rad did not affect the breaking strength of silicone rubber tubes but caused a reduction of breaking strength of latex rubber tubes. These findings suggest that silicone rubber has advantages over latex rubber as a material for prosthetic oesophageal tubes.

Aged↗
PubMed1966

The biosynthesis of rubber: Incorporation of isopentenyl pyrophosphate into purified rubber particles by a soluble latex serum enzyme.

1. The rubber particles in Hevea brasiliensis latex have been partially purified by ;washing' with buffer solution, and separated into active fractions of different particle size. 2. The enzyme responsible for incorporating isopentenyl pyrophosphate into rubber is distributed between the surface of the rubber particles and the aqueous serum phase of the latex. The enzyme at the surface can be removed or inactivated if the rubber particles are washed sufficiently with buffer solution. Enzyme in the serum phase can be concentrated by fractional precipitation with ammonium sulphate. 3. To incorporate isopentenyl pyrophosphate into rubber in vitro, active rubber particles are required as well as enzyme and soluble cofactors. The activity of the rubber particles per unit surface area increases with diminishing particle size.

Journal Article↗
PubMed1990

Nutritive value of rubber seed (Hevea brasiliensis) meal: utilization by growing pigs of semipurified diets in which rubber seed meal partially replaced soybean meal.

Thirty-six four-way cross (Chester White X Landrace X Large White X Yorkshire) growing barrows and gilts were used to investigate the effects of replacing graded levels of protein from soybean meal with equivalent levels of protein from rubber seed meal in 16% CP semipurified diets on the performance characteristics, hematocrit, plasma metabolites and N utilization of pigs. The first diet (control) was largely cornstarch-soybean meal in which the soybean meal supplied all of the CP. In other diets, rubber seed meal replaced 10%, 20% and 30%, respectively, of the protein of soybean meal in the control diet. Twenty gilts were used in a 28-d growth trial and 16 barrows were used in an 8-d digestion trial (4-d collection). There were no differences (P greater than .05) in ADG, ADF intake and in the feed:gain ratios, even though there was a trend for lower ADG and gain:feed ratio as the level of rubber seed meal increased in the diet. There were no differences in hematocrit, but plasma protein and albumin tended to be depressed when rubber seed meal provided more than 10% of the dietary protein. Apparent digestibilities of GE, DM and N were lower with rubber seed meal at 20% of the protein than with any other diet, but apparent N retained and the percent of digested N retained were not depressed significantly (P greater than .05). Although rubber seed meal protein is of poorer quality than soybean meal protein for growing pigs, at least 10% of dietary protein can be provided by rubber seed meal without adversely affecting growth and N utilization.

Animal Feed↗
PubMed1989

Amino acid sequence of rubber elongation factor protein associated with rubber particles in Hevea latex.

The amino acid sequence of rubber elongation factor, a recently discovered protein tightly bound to rubber particles isolated from the commercial rubber tree Hevea brasiliensis, is presented. The role of this protein in rubber elongation and its interaction with prenyltransferase and rubber particles have been discussed in the preceding paper in this series (Dennis, M. S., and Light, D. R. (1989) J. Biol. Chem. 264, 18608-18617). Trypsin, Staphylococcus protease, chymotrypsin, acetic acid, and hydroxylamine cleavage were used to generate peptide fragments that were isolated by reverse phase high pressure liquid chromatography and analyzed by amino acid composition and automated Edman degradation. Each digest contained one blocked peptide identified as the amino terminus. The blocked amino-terminal peptide from the tryptic digest was analyzed by amino acid composition, fast atom bombardment mass spectrometry (molecular ion 1659.9), subdigested with Staphylococcus protease for partial sequence analysis, and finally deblocked with bovine liver acyl-peptide hydrolase removing an acetylalanine to allow analysis by Edman degradation. Rubber elongation factor is 137 amino acids long, has a molecular mass of 14,600 daltons, and lacks four amino acids: cysteine, methionine, histidine, and tryptophan. The NH2 terminus is highly charged and contains only acidic residues (5 of the first 12 amino acids). The first four amino acids are highly represented in other known NH2-terminally acetylated proteins. Comparison of the sequence of rubber elongation factor with other known sequences does not reveal significant sequence similarities that would suggest an evolutionary relationship.

Acetates↗
PubMed1996

The 14.6 kd rubber elongation factor (Hev b 1) and 24 kd (Hev b 3) rubber particle proteins are recognized by IgE from patients with spina bifida and latex allergy.

Two major water-insoluble proteins are located on the surface of rubber particles in Hevea brasiliensis latex. A 14.6 kd protein (Hev b 1), found mainly on large rubber particles (> 350 mm in diameter), and a 24 kd protein (Hev b 3), found mainly on small rubber particles (average diameter, 70 nm), are recognized by IgE from patients with spina bifida and latex allergy. Although Hev b 1 (also called the rubber elongation factor [REF]) has previously been reported as a major latex allergen, this conclusion has been disputed on the basis of results from other studies. The allergenicity of Hev b 1 is verified in this study by testing the recombinant protein generated from its gene. Because allergenicity is confined to patients with spina bifida and not observed in adults sensitive to latex, it is not a major latex allergen. The identification of Hev b 3 as another allergen originating from rubber particles is confirmed by immunogold labeling and electron microscopy. Observations with the monoclonal antibody USM/RC2 developed against Hev b 3 show that the protein has a tendency to fragment into several polypeptides of lower molecular weight (from 24 kd to about 5 kd) when stored at -20 degrees C. There is also indication of protein aggregation from the appearance of proteins with molecular weights greater than 24 kd. Fragmentation of Hev b 3 is induced immediately on he addition of latex B-serum, which is normally compartmentalized in the lutoids in fresh latex. In the preparation of ammoniated latex (used for the manufacture of latex products), the lutoids are ruptured, and the released B-serum reacts with Hev b 3 on the rubber particles to give rise to an array of low molecular weight polypeptides that are allergenic to patients with spina bifida.

Adult↗
PubMed1996

Natural rubber latex skin testing reagents: safety and diagnostic accuracy of nonammoniated latex, ammoniated latex, and latex rubber glove extracts.

BACKGROUND: Nonammoniated latex, ammoniated latex, and rubber glove extracts are the only sources of natural rubber (Hevea brasiliensis) latex that have potential for use as skin testing reagents in the diagnosis of latex allergy. Their diagnostic sensitivity and specificity as skin test reagents are unknown. OBJECTIVE: We conducted a phase 1/2 clinical study to examine the safety and diagnostic accuracy (sensitivity and specificity) of nonammoniated latex, ammoniated latex, and rubber glove extracts as skin test extracts to identify the most efficacious source material for future skin test reagent development. METHODS: Twenty-four adults not allergic to latex, 19 adults with hand dermatitis or pruritus, and 59 adults with a latex allergy were identified by clinical history. All provided blood and then received puncture skin tests and intradermal skin tests with nonammoniated latex, ammoniated latex, and rubber glove extracts from Malaysian H. brasiliensis latex by use of sequential titration. A glove provocation test and IgE anti-latex RAST were used to clarify positive history-negative skin test response and negative history-positive skin test response mismatches. RESULTS: All three extracts were biologically safe and sterile. After normalization to 1 mg/ml of total protein, all three extracts produced equivalent diagnostic sensitivity and specificity in puncture skin tests and intradermal skin tests at various extract concentrations. Optimal diagnostic accuracy was safely achieved at 100 micrograms/ml for intradermal skin tests (e.g., nonammoniated latex: puncture skin test sensitivity 96%, specificity 100%; intradermal skin test sensitivity 93%, specificity 96%). The presence of IgE antibody in skin was highly correlated with IgE anti-latex in serum (nonammoniated latex: r = 0.98, p < 0.001; ammoniated latex: r = 0.94, p < 0.001; rubber glove extract: r = 0.96, p < 0.001). All five available subjects with a positive history, negative skin test response, and absence of IgE antibody in serum had a negative glove provocation test response, indicating no clinical evidence of latex allergy. No systemic or large local allergic reactions were observed with puncture skin tests or intradermal skin tests. CONCLUSIONS: Equivalent diagnostic sensitivity and specificity were observed with the nonammoniated latex, ammoniated latex, and rubber glove extract skin test reagents after normalization for total protein; nonammoniated latex may be considered the reagent of choice on the basis of practical quality control and reproducibility considerations.

Adult↗
PubMed2000

Mutagenic profile of rubber dust and fume exposure in two rubber tire companies.

The aim of this study was to evaluate current mutagenic activity of ambient rubber dust and fume exposure in the mixing and curing departments of two rubber tire companies situated in The Netherlands and Sweden. Salmonella typhimurium strains YG1021, YG1024 and YG1041 were used to study the possible presence of mutagenic nitroarenes and aromatic amines. A large difference in mutagenic activity was found between the two companies. While the rubber tire company situated in The Netherlands revealed overall high mutagenic activity of rubber dust and fumes in the mixing and curing departments, respectively, 430 and 279 rev/m(3) (YG1041), the Swedish company showed almost no mutagenic activity, respectively, 18 and 54 rev/m(3) (YG1041). Further identification of the mutagenic profile showed that mutagenic activity was exclusively observed in S. typhimurium strains with elevated levels of O-acetyltransferase activity (YG1041 and YG1024) in the presence of a metabolic active liver S9 fraction, possibly indicating the presence of indirect mutagenic aromatic amines. These results show that although production processes and lay-out within rubber tire companies are comparable, differences in rubber chemicals used and overall level of control measures (e.g., good housekeeping, cleanliness) are likely to result in substantial differences in mutagenic exposure levels between companies.

Acetyltransferases↗