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PubMedDate not supplied

Structural characterization of rubber from jackfruit and euphorbia as a model of natural rubber.

A structural study of low molecular weight rubbers from Jackfruit (Artocarpus heterophyllus) and Painted spurge (Euphorbia heterophylla) was carried out as model compounds of natural rubber from Hevea brasiliensis. The rubber content of latex from Jackfruit was 0.4-0.7%, which is very low compared with that of 30-35% in the latex from Hevea tree. The rubber from Jackfruit latex was low molecular weight with narrow unimodal molecular weight distribution (MWD), whereas that obtained from E. heterophylla showed very broad MWD. The 1H and 13C NMR analyses showed that Jackfruit rubber consists of a dimethylallyl group and two trans-isoprene units connected to a long sequence of cis-isoprene units. The alpha-terminal group of Jackfruit rubber was presumed to be composed of a phosphate group based on the presence of 1H NMR signal at 4.08 ppm corresponding to the terminal =CH-CH2OP group.

Artocarpus↗
PubMedDate not supplied

Identification and characterization of genes from Streptomyces sp. strain K30 responsible for clear zone formation on natural rubber latex and poly(cis-1,4-isoprene) rubber degradation.

Streptomyces sp. strain K30 was isolated from soil next to a city high way in Münster (Germany) according to its ability to degrade natural and synthetic poly(cis-1,4-isoprene) rubber and to form clear zones on natural rubber latex agar plates. The clear zone forming phenotype was used to clone the responsible gene by phenotypic complementation of a clear zone negative mutant. An open reading frame (lcp) of 1,191 bp was identified, which was preceded by a putative signal sequence and restored the capability to form clear zones on natural rubber latex in the mutant. The putative translation product exhibited strong homologies (50% aa identity) to a putative secreted protein from Streptomyces coelicolor strain A3(2), another clear zone forming strain. Heterologous expression of lcp of Streptomyces sp. strain K30 in Streptomyces lividans strain TK23 enabled the latter to form clear zones on latex-overlay agar plates and to accumulate a degradation product of about 12 kDa containing aldehyde groups. Two ORFs putatively encoding a heterodimeric molybdenum hydroxylase (oxiAB) were identified downstream of lcp in Streptomyces sp. strain K30 strain which exerted a positive effect on clear zone formation and enabled the strain to oxidize the resulting aldehydes. Heterologous expression of a fragment harboring lcp plus oxiAB in S. lividans TK23 resulted in accumulation of aldehydes only in the presence of 10 mM tungstate. Determination of protein content during cultivation on poly(cis-1,4-isoprene) revealed an increase of the cellular protein, and gel permeation chromatography analysis indicated a shift of the molecular weight distribution of the rubber to lower values in the transgenic S. lividans strains and in the wild type, thus confirming utilization and degradation of rubber. Therefore, for the first time, genes responsible for clear zone formation on natural rubber latex and synthetic cis-1,4-polyisoprene degradation in Gram-positive bacteria were identified and characterized.

Aldehydes↗
PubMed2002

Type I allergy to natural rubber latex and type IV allergy to rubber chemicals in health care workers with glove-related skin symptoms.

BACKGROUND: It has been established that there are type I and type IV allergens in latex gloves. OBJECTIVE: The purpose of the study was to establish the prevalence of rubber glove-induced skin symptoms among health care workers in one Italian hospital. METHODS: Health care workers (n = 1584) were evaluated using a written questionnaire and 295 respondents with glove-induced skin symptoms were tested. We performed: skin prick test with latex glove extract and commercial latex, and environmental and food allergens; glove use test; patch tests with a rubber additive series; and RASTs. RESULTS: Hospital employees who used or had used latex gloves at work were 1294. Three hundred and sixteen (24.4%) reported glove-induced symptoms, namely, cutaneous symptoms in all the cases and non-cutaneous symptoms in 105 subjects (8.1%). Twenty-seven of the 295 symptomatic employees tested (9.1%) were latex sensitive. Thirty-one patients (10.5%) exhibited positive patch test to rubber-related allergens. The most positive readings were obtained from the Thiuram mix and the Carba mix, with 12 and 9 positivities, respectively. The risk factors for latex skin sensitization were: a previous history of atopy and asthma; history of surgery; pre-existing hand dermatitis; work-related symptoms; and positive skin tests to common inhalant and certain foods (P < 0.05). Subjects who exhibited positive patch test were significantly more likely to have a prior hand dermatitis (P < 0.001). Of the 295 cases, 275 (93.2%) were contact dermatitis (CD), 13 (4.4%) contact urticaria (CU) (including protein CD) and 7 (2.4%) CD associated with CU. CONCLUSIONS: Our results show a high prevalence of rubber glove-induced dermatoses among the employees in one Italian hospital. The majority of skin complaints of latex gloves are related to skin irritation rather than to allergy. The immediate allergy to latex and the delayed allergy to rubber chemicals suggest that all the health care workers with glove-related dermatitis should undergo both skin prick test and glove use test to detect type I hypersensitivity to latex, and patch test to detect type IV hypersensitivity to rubber chemicals.

Adult↗
PubMed2003

A comparison of the simultaneous application of sclerotherapy and rubber band ligation, with sclerotherapy and rubber band ligation applied separately, for the treatment of haemorrhoids: a prospective randomized trial.

OBJECTIVE: To compare simultaneous application of sclerotherapy and rubber band ligation, with sclerotherapy and rubber band ligation applied separately for the treatment of 2nd degree haemorrhoids. PATIENTS AND METHODS: Between 1993 and 1996, 255 patients that suffered from 2nd degree haemorrhoids were divided into 3 groups of 85 patients, each to receive either simultaneous sclerotherapy for smaller and rubber band ligation for larger piles (SCL/RBL) in one session, or sclerotherapy (SCL), or rubber band ligation (RBL), respectively. After a period of 4 years all patients were examined and their symptoms were recorded. RESULTS: The patients of the SCL group developed significantly fewer complications after treatment compared to the other two methods (P < 0.001), which did not differ from each other. After the SCL/RBL treatment, significantly more patients were symptom free (46%) than after SCL (8%), P < 0.001. There was no significant difference between the SCL/RBL (46%) and the RBL (31%) groups (P = 0.217), although the combined treatment seemed to be more effective than rubber band ligation. Only 10% of the patients of the SCL/RBL group needed additional sessions 6-24 months after the initial treatment compared to 30% of the patients of the SCL group (P = 0.001). However, there was no significant difference between SCL/RBL and RBL (17%) groups (P = 0.151). CONCLUSION: The combination of sclerotherapy and rubber band ligation for treatment of 2nd degree haemorrhoids is significantly more efficient than sclerotherapy on its own.

Combined Modality Therapy↗
PubMed2000

Effect of pretreatment of rubber material on its biodegradability by various rubber degrading bacteria.

The effect of pretreatment of several cis-1,4-polyisoprene containing rubbers on their biodegradability was examined. Tests were carried out with six recently isolated and characterized rubber degrading bacteria belonging to the genera Gordonia (strains Kb2, Kd2 and VH2), Mycobacterium, Micromonospora and Pseudomonas. All strains were able to use natural rubber (NR) as well as NR latex gloves as sole carbon source. Extraction of NR latex gloves by organic solvents resulted in an enhancement of growth for three of the selected strains. On the other hand, growth of Gordonia sp. (strain Kb2 and Kd2), Mycobacterium fortuitum NF4 and Micromonospora aurantiaca W2b on synthetic cis-1,4-polyisoprene did only occur after removal of the antioxidants, that are usually added during manufacture to prevent aging of the materials. Detailed degradation studies performed with Gordonia sp. Kb2 revealed an enhanced mineralization of pretreated NR latex gloves and mineralization of purified natural rubber (NR), indicating the actual mineralization of cis-1,4-polyisoprene rubber constituent even after removal of non-rubber constituent that may act as co-metabolic substrate and support microbial growth. Further analysis by scanning electron microscopy (SEM) clearly demonstrated the enhanced colonization efficiency of these bacteria towards pretreated NR latex gloves. Colonization was additionally visualized by staining of overgrown NR latex gloves with Schiff's reagent, and the purple color produced in the area of degradation was an evidence for the accumulation of aldehydes containing oligomers. Further enhancement of latex gloves degradation could be achieved after successive replacement of mineral salts medium during cultivation. Thereby, a rapid disintegration of untreated NR latex gloves material was accomplished by Gordonia sp. strain VH2.

Actinomycetales↗
PubMed1996

Cloning, characterization, and heterologous expression of cDNAs for farnesyl diphosphate synthase from the guayule rubber plant reveals that this prenyltransferase occurs in rubber particles.

Two farnesyl diphosphate synthase (FPS) cDNA's from a guayule stembark library were isolated and characterized. Both encode M(r) 39,000 proteins containing 432 amino acids that differ slightly in their deduced molecular weights and isoelectric points. They both contain the DDXXD motifs that are characteristic of prenyltransferases, and both isoforms show high homology to other plant FPS sequences but less overall homology to FPS sequences from nonplant sources. The two isoforms differ by 5% in their amino acid sequence. When expressed in Escherichia coli, each guayule isoform exhibits high specific activity that produces farnesyl diphosphate as the major isoprenoid and small amounts of geranyl diphosphate. Biochemical and immunological evidence also indicates that FPS is associated with guayule rubber particles. Antibodies to chicken FPS cross-react with both guayule isoforms expressed in E. coli and recognize a low abundance M(r) 39,000 protein in rubber particles purified from guayule stembark. Guayule FPS sequences show high homology to peptide fragments of the prenyltransferase associated with rubber particles from Hevea brasiliensis, suggesting that this enzyme may be important for rubber biosynthesis in both species.

Alkyl and Aryl Transferases↗
PubMed2001

Rubber foreign bodies in puncture wounds of the foot in patients wearing rubber-soled shoes.

We report 8 cases of puncture wound of the foot associated with rubber foreign bodies in patients who were wearing rubber-soled shoes. The difficulty in making the correct diagnosis and the complications arising from these injuries are reviewed. The morbidity associated with these seemingly innocuous puncture wounds can be serious. Infective complications resolved only with removal of all imbedded rubber foreign bodies. A history of wearing rubber-soled shoes during the injury and a high index of suspicion may prevent complications.

Adult↗
PubMed2000

Natural rubber latex aeroallergen exposure in rubber plantation workers and glove manufacturers in Thailand and health care workers in a UK hospital.

OBJECTIVES: To estimate personal airborne natural rubber latex (NRL) concentrations for three occupational exposure groups; rubber plantation workers and NRL glove manufacturers in Thailand and health care workers in the UK. To utilise these data to classify the populations into appropriate exposure groups for the exposure-response analysis in the epidemiological study on latex allergy. METHODS: Two rubber plantations (110 workers), three NRL glove manufacturing factories (583 workers) in Thailand and one UK hospital (490 workers) were selected for the study. A preliminary workplace survey was carried out at each workplace in order to assign job titles subjectively in to high, moderate or low exposure groups for the purpose of sample selection. Between 5 and 20% of workers from each group for the three populations were then selected randomly for personal measurement of latex airborne allergens. Personal sampling was conducted using a 25 mm PTFE filter loaded in to an IOM sampling head at 2 l. min(-1). NRL aeroallergens were measured by an inhibition assay with NRL-specific IgE antibodies from NRL-sensitised people. RESULTS: A total of twenty-two personal samples were collected from plantation workers, sixty-one samples from the glove manufacturer employees and twenty seven from health care workers. The highest geometric mean (GM) NRL aeroallergen concentration was found in the glove manufacturing factories (7.3 microg m(-3)), followed by the rubber plantations (2.4 microg m(-3)) and the UK hospital (0.46 microg m(-3)). Amongst the NRL glove factories, the NRL aeroallergen concentrations were highest for those conducting the following tasks; glove stripping, glove inspections and packing of powdered gloves. The GM NRL aeroallergen for these tasks were in the range of 12.9 to 17.8 microg m(-3). CONCLUSIONS: In the process from tapping and manufacture of latex gloves through to their use the highest exposure to NRL aeroallergens is likely to occur in the manufacturing factories. Exposure to aeroallergens for the plantation workers was considered to be moderate and that of health care workers to be low.

Agriculture↗
PubMed2002

Occupational exposure to rubber vulcanization products during repair of rubber conveyor belts in a brown coal mine.

Several hundred chemical compounds were found in workroom environments in the rubber industry, but most of the published exposure data relate to the production of tyres; information from the "non-tyre" sections are very limited, if any. This study was carried out to identify chemical substances and measure their air concentrations in the repair shop of a brown coal mine in which damaged rubber conveyor belts were repaired. GC-MS and HPLC analysis of stationary air samples resulted in identification of aliphatic and aromatic hydrocarbons to C12, PAHs, alcohols, phenols, ketones, heterocyclic nitrogen and sulfur compounds. Quantitative evaluation of occupational exposure included determination of organic compound vapours collected on charcoal (GC-MSD), polycyclic aromatic hydrocarbons (HPLC), N-nitrosoamines and other amines (GC-NPD) and DNPH derivatives of aldehydes (HPLC) in the breathing zone of workers representing all job titles. The concentrations of investigated compounds were very low. Carcinogenic substances: N-nitrosoamines, benzene, PAHs were not present in workroom air in concentrations exceeding limits of detection of the analytical methods being applied; concentrations of methylisobutylketone, tetrachloroethylene, naphtha, aromatic hydrocarbons, phthalates and aldehydes were much lower than the respective occupational exposure limit values. The results indicate much lower exposure than that reported in the production of tyres and other fabricated rubber products.

Carcinogens↗
PubMed1994

[Occupational contact dermatitis induced by allergens present in rubber. I. Allergy to rubber accelerators].

During the period between January 1989 and 15 April 1994 allergy to chemical compounds present in rubber was found in 51 (15%) out of 339 patients with occupational dermatitis. In this group (20 workers of the metallurgical industry, 15 health service workers, 6 workers of the building and 3 of the rubber industries, 2 farmers and 5 drivers) the frequency of allergy to 15 accelerators of the thiuram group, thiocarbamates, thiazoles as well as derivatives of diphenylguanidine and thiocarbamide was investigated. Thiurams caused over-sensitivity in 52.9% of patients, thiocarbamates in 41.2%, thiazoles in 35.3%, guanidine derivatives in 11.8% and thiocarbamide in 9.8%. In general, allergy to thiocarbamates was concomitant with allergy to thiurams (20 out of 21 patients allergic to carbamates) and over-sensitivity to thiazoles was very often parallel to allergy to thiurams (8 out of 18 patients allergic to thiazoles). Accelerators present in the rubber of protective gloves proved to be the most frequent source of allergy especially in health service workers.

Adult↗
PubMed1990

Silicone rubber-hydrogel composites as polymeric biomaterials. I. Biological properties of the silicone rubber-p(HEMA) composite.

A composite material was prepared consisting of silicone rubber matrix and particulate lightly cross-linked poly(2-hydroxyethyl methacrylate) (p(HEMA] hydrogel. The material resembling common silicone rubber is hydrophilic and swells in water like hydrogels. The effects of the implanted composite on tissues of the living organism were tested in rats by methods assessing local acute and chronic inflammatory reactions and calcification by means of radioactive indicators and by histological examination. Results of a 6 month implant study indicated no difference in reactions of the animal body on the silicone rubber-p(HEMA) composite and a non-toxic, non-irritant pure solid p(HEMA) control.

Animals↗
PubMed1987

N-nitrosamines and nitrosatable compounds in rubber nipples, pacifiers and other rubber and plastic commodities.

In 1983 and 1985, rubber teats and pacifiers from the Dutch market were analysed for N-nitrosamines (NA) and nitrosatable compounds (NC) by extraction with an artificial saliva test solution (24 h, 40 degrees C). NC were determined as NA (gas chromatography-thermal energy analysis) after nitrosation. In 1983, the total content of NA and NC varied from 4-40 micrograms/kg and 50-3700 micrograms/kg, respectively (18 samples). In 1985, NA and NC varied from 3-94 micrograms/kg and 26-5100 micrograms/kg, respectively (20 samples). According to Dutch legislation, teats may contain no more than 1 microgram/kg and 20 microgram/kg NA and NC. Of other rubber and plastic commodities analysed, balloons contained levels of up to 120 micrograms/kg and 2800 micrograms/kg NA and NC.

Cooking and Eating Utensils↗
PubMed1993

The rubber elongation factor of rubber trees (Hevea brasiliensis) is the major allergen in latex.

BACKGROUND: Allergy to latex-containing articles is becoming more and more important because it can result in unexpected life-threatening anaphylactic reactions in sensitized individuals. METHODS: A protein of 58 kd with an isoelectric point of 8.45 was purified from raw latex and from latex gloves and identified as the major allergen, completely blocking specific IgE antibodies in the serum of latex-sensitized subjects. The allergen is a noncovalent homotetramer molecule, in which the 14.6 kd monomer was identified, by amino acid composition and sequence homologies of tryptic peptides, to be the rubber elongation factor found in natural latex of the Malaysian rubber tree. RESULTS: Competitive immunoinhibition tests showed that the starch powder covering the finished gloves is the airborne carrier of the allergen, resulting in bronchial asthma on inhalation. The purified allergen can induce allergic reactions in the nanogram range. CONCLUSION: The identification of the allergen (Hev b I) may help to eliminate it during the production of latex-based articles in the future.

Allergens↗
PubMed1998

[Hygienic evaluation and analytical methods for the silicon rubber rubber intended to come into contact with food. Part I. Determination of the migration of the soluble substances into the aqueous model fluids].

The review of the regulations for the silicon rubber intended to come into contact with food in some European countries and USA was performed. On the basis of these regulations the principles of the hygienic evaluation and the analytical models for the testing of silicon rubber and elastomers contacting with food in Poland was presented. The testing include: sensoric analysis; migration of the soluble substances into aqueous model fluids; volatile substances; hardeners; catalyzers; migration of certain heavy metals; N-nitrosamines and N-nitrosatables. Some of these methods have been published in Polish Standards or in the Methodical Publications of the National Institute of Hygiene.

Catalysis↗
PubMed1994

[Christopher Columbus, rubber, and rubber nipples].

The author quickly traces the history of rubber, making note of the pharmacists who therein played a role. He exhibits the history of rubber nipples and that of infant bottles, of which one of the most widely used was the "Robert Bottle."

Bottle Feeding↗
PubMed2002

Allergic reactions to natural rubber latex at home, to rubber products, and to cross-reacting foods.

The prevalence of clinical sensitivity to natural rubber latex (NRL) has increased dramatically in the last 15 years. In the health care setting this has been associated with the increased use of latex gloves. It does not, however, explain the observation that IgE antibodies to NRL are detected in equal rates in both health care workers and the general population, with the numerous reactions occurring in homes and in health care settings in non-health care workers. This increase in NRL sensitivity has occurred at the same time as our observation of an increase in atopy. In addition, atopy is a definite risk factor that has been associated with NRL sensitivity in all studies. Exposure to NRL products outside the health care environment is significant and ubiquitous. Exposure to NRL epitopes also occurs by ingestion of foods, food additives, and pollen. This exposure is sufficient to induce IgE antibodies to both the food and NRL proteins. It is therefore difficult in an individual patient to implicate any single product as the cause of NRL sensitization leading to the development of symptoms. Outside of the health care environment there does not appear to be an increase in exposure to NRL products or to cross-reacting materials. This would suggest that there is an increase in the susceptible population, which clearly appears to be the atopic individual. A great deal of attention is devoted to reducing exposure to latex gloves in the health care setting, which may be only the visible portion of the iceberg. More attention should be devoted to reducing the antigens present in all NRL products and consideration given to developing vaccines for the food-sensitive individuals.

Allergens↗