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At least 163 records · Page 9Linked to original sources
PubMed1995

Prohevein from the rubber tree (Hevea brasiliensis) is a major latex allergen.

BACKGROUND: There is general agreement that proteins eluting from different natural rubber latex products can cause immediate type hypersensitivity reactions in latex-allergic patients. However, there is as yet no consensus as to what are the most important allergens in natural rubber latex. OBJECTIVE: We wanted to purify and characterize at the primary structure level three natural latex proteins, suggested to represent significant allergens. METHODS: Proteins were purified from ultracentrifuged bottom fraction of natural rubber latex using high performance liquid chromatography gel filtration and reversed phase chromatography. Purified proteins were subjected to tryptic cleavage, peptide separation and amino acid sequencing. Immunoblotting was used to demonstrate IgE antibodies to the purified proteins in sera from latex-allergic patients. RESULTS: A 20 kDa protein was identified by amino acid sequencing as prohevein, a major protein in the rubber tree Hevea brasiliensis, and a 30 kDa natural rubber latex protein as hevamine, another essential rubber tree protein. A third, previously undescribed natural rubber latex protein, showed high homology to several plant endo-1,3-beta-glucosidases. In immunoblotting, the purified prohevein bound IgE antibodies from 24/29 (83%) sera of latex-allergic patients including positive results in 4/6 latex-allergic children with spina bifida or other congenital anomalies. The purified prohevein elicited positive skin-prick test reactions in all six latex-allergic patients showing IgE to prohevein. The purified 36 kDa protein bound IgE from 6/29 (21%) latex-allergic sera, and the purified hevamine from only 1/29 patient sera. CONCLUSION: The observed high frequency of IgE antibodies to prohevein suggests that this protein is a major natural rubber latex allergen.

Adolescent↗
PubMed2004

Gingival cell proliferation induced by use of a sonic toothbrush with warmed silicone rubber bristles.

BACKGROUND: Toothbrushing promotes gingival cell proliferation, which may occur as the result of the physical stimulation of the gingiva. The present study evaluated the effects of temperature and silicone rubber bristles of a sonic toothbrush on gingival cell proliferation in dogs. METHODS: During the 5-week experimental period, one quadrant in each of eight dogs received a different toothbrushing regimen: a manual toothbrush or a sonic toothbrush with 1) nylon, 2) silicone rubber, or 3) warmed silicone rubber bristles. The proliferative activity of gingival cells was evaluated based on expression of proliferating cell nuclear antigen (PCNA). RESULTS: Use of the sonic toothbrushes produced a higher density of PCNA-positive and total fibroblasts than did use of a manual toothbrush. The warm silicone rubber bristles resulted in a higher density of PCNA-positive fibroblasts compared with the cooler silicone rubber bristle. The number of PCNA-positive basal cells in the junctional epithelium also increased following electric toothbrushing with warmed silicone rubber bristles. CONCLUSIONS: The sonic toothbrush with silicone rubber bristles induced gingival fibroblast proliferation to a greater degree than a manual toothbrush. Warming the silicone rubber bristles increased their stimulatory effects on the proliferative activity of gingival cells.

Analysis of Variance↗
PubMed1992

Allergic reactions to natural rubber.

Immediate hypersensitivity reactions to natural rubber pose a significant risk to patients with spina bifida and urogenital abnormalities, health care workers, and rubber industry workers. Other patients, outside of these high risk groups, have experienced severe allergic reactions to natural rubber as well. Awareness of this life-threatening condition by health care providers is essential if reactions are to be prevented. History alone is inadequate to identify all patients at risk, and reliable testing materials are not yet approved or widely available. Nonrubber medical devices are readily available for most uses; however, the only rubber-free condoms currently on the market do not prevent the transmission of sexually transmitted disease. The identification and detection of rubber antigens, along with mandated labeling for rubber antigen content, will contribute to the care of this growing population of patients. Efforts by the rubber industry to decrease the antigen content of natural rubber products will decrease the risk of reaction among sensitized patients and will, very likely, decrease the rate of sensitization in the future.

Humans↗
PubMed1996

Longitudinal study of respiratory findings in rubber workers.

A cross-sectional assessment of respiratory function and symptoms was performed in 1985 on 409 male rubber workers and 172 unexposed control workers. A follow-up study in 311 of the original rubber workers was performed 6 years later. Ventilatory capacity was measured by recording maximum expiratory flow-volume (MEFV) curves. At the time of the initial study, significantly higher prevalences of all chronic respiratory symptoms, except for asthma, were found among the rubber workers compared to controls. Smokers had a significantly higher prevalence of most of the chronic respiratory symptoms compared with nonsmokers. A high prevalence of acute symptoms during the workshift was recorded among the rubber workers at both surveys. Rubber workers demonstrated significantly lower ventilatory capacity measurements compared to predicted. Ventilatory capacity measurements diminished significantly across the workshift, particularly FEF50 and FEF25. Metaproterenol inhaled at the end of the workshift significantly improved lung function in a small group of sensitive rubber workers. Annual lung function loss among both smokers and nonsmokers was in excess of predicted. Our data suggest that exposure to noxious agents in the rubber industry are associated with the development of acute and chronic respiratory impairment.

Adolescent↗
PubMed1980

Time-dependent failure of a polyolefin rubber candidate material for blood pump applications.

Failure behavior of a polyolefin elastomer which is a candidate material for blood pump applications has been studied under uniaxial and equibiaxial test conditions. Both static and dynamic (fatigue) testing were performed to study four aspects of material failure behavior as suggested by a cumulative damage failure model. Results from testing a standard formulation butyl rubber are presented for comparison. Our results show that the uniaxial failure behavior under static loads for the butyl rubber is superior to that of the polyolefin rubber at high loads but that the polyolefin is superior at low loads. Under fatigue loading conditions, the failure times for both rubbers decrease with increasing test frequency. The observed frequency dependence lies between that predicted by the cumulative damage model and that predicted by a cycle dependent fatigue model. The distribution of failure times for the polyolefin rubber is broader than that for the butyl rubber. For both uniaxial and equibiaxial testing, the distribution of failure times changes in going from the static testing to dynamic testing. This is true for both rubbers.

Assisted Circulation↗
PubMed1994

Bacterial translocation after intraperitoneal implantation of rubber fragments in the splenectomized rat.

The aim of the present study was to determine the influence of splenectomy on the incidence of enteric bacterial translocation in rats with intraperitoneal rubber drain implantation. Male Sprague-Dawley rats (250-300 g) underwent splenectomy or sham operation 7 days prior to the intraperitoneal implantation of rubber drain fragments (7 cm2). Bacterial translocation was measured 2 days after rubber drain implantation. The incidence of bacterial translocation was significantly higher in the group with intraperitoneal rubber drain implantation plus sham splenectomy than in the groups with sham splenectomy plus sham implantation, splenectomy plus sham implantation or splenectomy plus rubber drain implantation. An increase in ileal permeability of 125I-human serum albumin was induced by intraperitoneal rubber drain implantation and ameliorated by splenectomy. Splenectomy also improved the impaired intestinal motility induced by intraperitoneal rubber drain implantation. Histological examination revealed a preserved normal mucosal architecture in splenectomized rats. Thus, splenectomy reduced the rate of enteric bacterial translocation induced by intraperitoneal biomaterial implantation.

Animals↗
PubMed2006

Comparative studies on crosslinked and uncrosslinked natural rubber biodegradation by Pseudomonas sp.

A comparative study on biodegradation of di-cumyl peroxide (DCP) crosslinked and uncrosslinked natural rubber by Pseudomonas sp. was carried out. Decrease in organic carbon content along with the changes in tensile strength of the treated rubber, both DCP crosslinked and uncrosslinked natural rubber, indicated rubber hydrocarbon utilization by the Pseudomonas sp. A decrease in 60.88% MPa and 41.66% MPa was observed after five month's old treated uncrosslinked natural rubber and DCP crosslinked rubber, respectively. Biodegradation was more pronounced in natural uncrosslinked rubber, which was further confirmed by the formation of aldehydic compounds with decrease in CH2 stretching frequencies.

Benzyl Compounds↗
PubMed2006

Identification and comparison of natural rubber from two Lactuca species.

Renewed interest in the identification of alternative sources of natural rubber to Hevea brasiliensis has focused on the Compositae family. In our search for Compositae models for rubber synthesis, we extracted latex from stems of two lettuce species: Lactuca serriola, prickly lettuce, and Lactuca sativa cv. Salinas, crisphead lettuce. Both species contained cis-1,4-polyisoprene rubber in the dichloromethane-soluble portions of their latex, and sesquiterpene lactones in their acetone-soluble portions. The rubber from both species and their progeny had molecular weights in excess of 1,000,000g/mol, and polydispersity values of 1.1. Rubber transferase activity was detected across a range of farnesyl diphosphate initiator concentrations, with decreased activity as initiator concentrations exceeded putative saturation. These results add lettuce to the short list of plant species that produce high molecular weight rubber in their latex. Due to the genomic and agronomic resources available in lettuce species, they provide the opportunity for further dissection of natural rubber biosynthesis in plants.

Lactones↗
PubMed1982

Estimation of volatile N-nitrosamines in rubber nipples for babies' bottles.

A method is described for the estimation of volatile N-nitrosamines in the rubber nipples of babies' bottles. In a study of rubber nipples from one manufacturer, N-nitrosodimethylamine, N-nitrosodiethylamine and N-nitrosopiperidine were determined by gas chromatography, using a thermal energy analyser, and their presence was confirmed by mass spectrometry with average levels of individual nitrosamines ranging from 22 to 281 ppb. When the nipples were sterilized in a conventional sterilizer together with milk or infant formula the three nitrosamines migrated into the milk or formula. Storing a bottle of milk with a rubber nipple inverted in it for 2 hr at room temperature or overnight in a refrigerator after sterilization resulted in an 8-13% average increase in the nitrosamine levels migrating into the milk. On repeated sterilization of a single nipple, the quantities of nitrosamines migrating into milk from rubber nipples declined steadily, but after seven sterilizations, nitrosamines were still readily detectable in the milk. Nitrosamine levels were higher in rubber nipples after sterilization, indicating the presence of nitrosamine precursors in the nipples. No nitrosamines were found in raw, uncured rubber. Chemical accelerators and stabilizers added during the vulcanization process are the source of the amine precursors in rubber nipples.

Bottle Feeding↗
PubMed2003

Potential of scrap tire rubber as lightweight aggregate in flowable fill.

Flowable fill is a self-leveling and self-compacting material that is rapidly gaining acceptance and application in construction, particularly in transportation and utility earthworks. When mixed with concrete sand, standard flowable fill produces a mass density ranging from 1.8 to 2.3 g/cm(3) (115-145 pcf). Scrap tires can be granulated to produce crumb rubber, which has a granular texture and ranges in size from very fine powder to coarse sand-sized particles. Due to its low specific gravity, crumb rubber can be considered a lightweight aggregate. This paper describes an experimental study on replacing sand with crumb rubber in flowable fill to produce a lightweight material. To assess the technical feasibility of using crumb rubber, the fluid- and hardened-state properties of nine flowable fill mixtures were measured. Mixture proportions were varied to investigate the effects of water-to-cement ratio and crumb rubber content on fill properties. Experimental results indicate that crumb rubber can be successfully used to produce a lightweight flowable fill (1.2-1.6 g/cm(3) [73-98 pcf]) with excavatable 28-day compressive strengths ranging from 269 to 1194 kPa (39-173 psi). Using a lightweight fill reduces the applied stress on underlying soils, thereby reducing the potential for bearing capacity failure and minimizing soil settlement. Based on these results, a crumb rubber-based flowable fill can be used in a substantial number of construction applications, such as bridge abutment fills, trench fills, and foundation support fills.

Conservation of Natural Resources↗
PubMed2003

Transcriptome analysis reveals novel features of the molecular events occurring in the laticifers of Hevea brasiliensis (para rubber tree).

Latex of Hevea brasiliensis (Willd. ex A, Juss.) Mull. Arg. (Brazilian rubber tree) contains 30-50% (w/w) of natural rubber (cis-1,4-polyisoprene), which is an important raw material for many industrial uses. In order to gain insights into the molecular events occurring in latex, we analyzed more than 20,000 cDNA-AFLP-based TDFs (transcription-derived fragments) and 1176 ESTs. The results revealed several novel features of the latex transcriptome. First, the repertoire of the genes expressed in latex is unique. Only seven gene families accounted for more than 51% of the latex transcriptome. Among them, two of the most abundant ESTs were the genes encoding rubber particle proteins REF (rubber elongation factor) and SRPP (small rubber particle protein), comprising 29% of the total ESTs. Unexpectedly, several genes involved in the rubber biosynthesis were expressed at low levels in the latex. In fact, genes encoding cis -prenyltransferase (CPT), a potential candidate for rubber polymerase, were not present in the EST pool because of their low expression level. However, we were able to clone four full-length cDNAs by screening the same latex cDNA library used in the EST analysis and confirmed their enzyme activity in vitro. The second most abundant transcripts were defense- or stress-related genes, suggesting that defense is one of the functions of laticifers. Finally, the presence of the non-mevalonate DXP/MEP pathway for IPP synthesis in latex was noted by up-regulation of the 1-deoxy-D-xylulose 5-phosphate synthase gene.

Amino Acid Sequence↗
PubMed1969

Th biosynthesis of rubber from beta-hydroxy-beta-methylgluarylcoenzyme A in Hevea brasiliensis latex.

1. beta-Hydroxy-beta-methyl[3-(14)C]glutaryl-CoA is efficiently incorporated into rubber on incubation with Hevea brasiliensis latex, and the incorporation is diminished in the presence of unlabelled mevalonate. beta-Hydroxy-beta-methylglutaric acid is not utilized for rubber synthesis, but inhibits the formation of rubber from beta-hydroxy-beta-methylglutaryl-CoA. 2. The incorporation of beta-hydroxy-beta-methylglutaryl-CoA into rubber is stimulated equally by NADP(+) and NADPH and less so by NAD(+) and NADH. ATP is slightly stimulatory and CoA is inhibitory. 3. beta-Hydroxy-beta-methylglutaryl-CoA reductase is concentrated in the sediment (bottom fraction) formed by centrifuging latex at low speed and the enzyme is unstable in the absence of cysteine or GSH. The formation of NADPH takes place in the latex serum. 4. There is a marked seasonal variation in the extent of beta-hydroxy-beta-methylglutaryl-CoA incorporation into rubber in latex, but mevalonate incorporation is relatively constant. This observation, together with the finding that beta-hydroxy-beta-methylglutaryl-CoA reduction is the rate-limiting step in the formation of rubber from beta-hydroxy-beta-methylglutaryl-CoA, suggests that the conversion of beta-hydroxy-beta-methylglutaryl-CoA into mevalonate is of importance in the regulation of rubber synthesis. 5. Evidence suggesting that beta-hydroxy-beta-methylglutaryl-CoA lyase is present in H. brasiliensis latex has been obtained.

Adenosine Triphosphate↗
PubMed2001

Natural rubber pharmaceutical vial closures release latex allergens that produce skin reactions.

BACKGROUND: The release of allergenic proteins from natural rubber vial closures (stoppers) into aqueous pharmaceuticals may induce allergic reactions in individuals with latex allergy (LA) receiving medications from such vials. OBJECTIVE: The goal of this study was to determine whether solutions stored in vials containing natural rubber closures release allergenic proteins detectable by skin testing of subjects with LA. METHODS: Five pharmaceutical vial closures (2 natural rubber and 3 synthetic) were coded, inserted onto vials containing phenol-saline-human serum albumin, and stored in an inverted position before use. Twelve volunteers with and 11 volunteers without LA underwent skin testing with solutions from each of the 5 vials, either those not punctured (0P) or those punctured 40 times with a 21-gauge needle 12 to 24 hours before testing (40P). RESULTS: All intradermal skin test responses in the group without LA were negative. Two and 5 of the 12 subjects with LA had positive intradermal skin reactions to 0P and 40P solutions, respectively, from vials containing rubber closures. Two subjects with LA had inexplicable, positive, nonreproducible intradermal skin test reactions to solutions from vials containing bromobutyl but not vials with isoprene synthetic closures. In vitro inhibition analysis detected 6 to 7 AU/g latex allergen in extracts of cut natural rubber containing closures but not in extracts of synthetic closures. CONCLUSION: Natural rubber vial closures released allergenic latex proteins into the tested solutions in direct contact during storage in sufficient quantities to elicit positive intradermal skin reactions in some individuals with LA. These data support a recommendation to eliminate natural rubber from closures of pharmaceutical vials.

Adolescent↗
PubMed2002

Long-term outcome of 160 adult patients with natural rubber latex allergy.

Allergy to natural rubber latex is a major occupational problem in the health care sector and a problem even in other occupations in which protective gloves are used. There is little information available about the long-term outcome at work in large patient populations. To study the occupational outcome when all gloves in the working environment were changed either to low-allergen latex or non-latex gloves, in 1995 to 1996 we re-examined 160 of 174 adult subjects who were diagnosed with natural rubber latex allergy between 1982 and 1994 after a median of 3 years (range, 0.5 to 24 years) after the diagnosis. The outcome in daily work or as a patient in health care was investigated with the use of a questionnaire. Special attention was paid to the assessment of the occurrence of hand eczema. Glove selection policy as an intervention in the treatment of natural rubber latex allergy is described. Of 71 health care workers and 89 non-health care workers, 72% and 83% were atopic; 54% and 65% had hand eczema at the time of diagnosis, and 89% and 19% had work-related allergy to natural rubber latex, respectively. On re-examination, none of the health care workers had changed work because of natural rubber latex allergy, and only 38% had hand eczema (significant decrease). Ninety-eight percent of the non-health care workers, of which 58% had hand eczema, continued with their previous jobs. The use of low-allergen latex or non-latex gloves throughout the health care sector seems to be an adequate step for health care workers who have natural rubber latex allergy; nonhealth care workers get along with personal avoidance of latex gloves if they are not working directly with natural rubber latexcontaining materials in production.

Adult↗
PubMed1993

Release of thiurams and carbamates from rubber gloves.

A method for quantitative determination of thiuram and carbamate derivatives released from rubber gloves into synthetic sweat is presented. The analysis was based upon determination of ester derivatives using gas-chromatography/mass spectrometry and isotope-dilution. The detection limit was 0.1 mg thiuram/carbamate in 200 ml synthetic sweat (0.5 ppm). The release of thiurams and carbamates from 5 household and 5 surgical types of gloves into synthetic sweat was determined. Each of the natural rubber gloves released varying amounts of thiurams (0-4.3 mg) as well as carbamates (0-8.1 mg). 22 thiuram-sensitized patients were patch tested with pieces of the gloves. Gloves releasing considerable amounts of thiurams and/or carbamates seemed to cause more positive patch test reactions in these patients than gloves releasing smaller amounts. Surgical gloves made from natural rubber caused a substantial larger number of positive patch test reactions than household gloves made from natural rubber. The amounts released per cm2 of the gloves were of the same order of magnitude as the content per cm2 patch test of thiuram mix, diluted 1:10. The accessibility of a quantitative, chemical analysis for thiurams and carbamates released from rubber gloves makes it reasonable to ask for declarations of rubber gloves. Proposals for threshold values for release of thiurams and carbamates from rubber gloves may be given in the future.

Carbamates↗
PubMed1994

Identification of causative chemicals of allergic contact dermatitis using a combination of patch testing in patients and chemical analysis. Application to cases from industrial rubber products.

3 cases of allergic contact dermatitis from industrial rubber products were investigated using a combination of patch testing in patients and chemical analysis of causative rubber products by gas chromatography (GC), GC-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC). Our studies revealed N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), a typical rubber allergen, as a causative chemical in a case from a brand of heavy-duty rubber gloves and a case from a black rubber ring for car manufacture, and zinc ethylphenyldithiocarbamate (ZEPC), a dithiocarbamate (DTC)-type accelerator, as a causative chemical in a case from a brand of rubber work gloves: both IPPD and ZEPC, which showed positive patch test reactions, were confirmed in the extracts of the causative rubber products by GC, GC-MS and/or HPLC.

Adult↗
PubMed2000

Biodegradation of cis-1,4-polyisoprene rubbers by distinct actinomycetes: microbial strategies and detailed surface analysis.

Several actinomycetes isolated from nature were able to use both natural rubber (NR) and synthetic cis-1,4-polyisoprene rubber (IR) as a sole source of carbon. According to their degradation behavior, they were divided into two groups. Representatives of the first group grew only in direct contact to the rubber substrate and led to considerable disintegration of the material during cultivation. The second group consisted of weaker rubber decomposers that did not grow adhesively, as indicated by the formation of clear zones (translucent halos) around bacterial colonies after cultivation on NR dispersed in mineral agar. Taxonomic analysis of four selected strains based on 16S rRNA similarity examinations revealed two Gordonia sp. strains, VH2 and Kb2, and one Mycobacterium fortuitum strain, NF4, belonging to the first group as well as one Micromonospora aurantiaca strain, W2b, belonging to the second group. Schiff's reagent staining tests performed for each of the strains indicated colonization of the rubber surface, formation of a bacterial biofilm, and occurrence of compounds containing aldehyde groups during cultivation with NR latex gloves. Detailed analysis by means of scanning electron microscopy yielded further evidence for the two different microbial strategies and clarified the colonization efficiency. Thereby, strains VH2, Kb2, and NF4 directly adhered to and merged into the rubber material, while strain W2b produced mycelial corridors, especially on the surface of IR. Fourier transform infrared spectroscopy comprising the attenuated total reflectance technique was applied on NR latex gloves overgrown by cells of the Gordonia strains, which were the strongest rubber decomposers. Spectra demonstrated the decrease in number of cis-1,4 double bonds, the formation of carbonyl groups, and the change of the overall chemical environment, indicating that an oxidative attack at the double bond is the first metabolic step of the biodegradation process.

Actinomycetales↗
PubMed1994

Allergy to natural rubber latex: a growing problem.

Immediate, IgE-mediated allergy to natural rubber latex has recently been found to be responsible for contact and generalized urticaria, protein contact dermatitis, rhinitis, asthma and even fatal anaphylactic reactions. The proteins present in latex from the rubber tree (Hevea brasiliensis) can still persist in rubber end-products where they are capable of sensitizing exposed users. Atopic people and those with hand eczema are prone to become sensitized by natural rubber latex, which often causes occupational problems in connection with the use of protective gloves. But people blowing up balloons and those using condoms are also at risk if their symptoms are misinterpreted. Severe adverse reactions caused by rubber products in medicare cannot be prevented if the diagnosis has not been made before operations and medical examinations. So the most important task today is to develop reliable and safe methods for diagnosing natural rubber latex allergy and to manufacture rubber products with fewer allergens.

Gloves, Protective↗