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At least 757 records · Page 42Linked to original sources
PubMed1999

Complementary effects of bifidogenic growth stimulators and ammonium sulfate in natural rubber serum powder on Bifidobacterium bifidum.

Natural rubber serum powder, rich in crude protein and carbohydrates, had a strong growth-stimulating activity for Bifidobacterium bifidum JCM 1254, which was unable to grow in a fully synthetic medium, B12 assay medium. Natural rubber serum powder was fractionated by ultrafiltration (molecular weight cutoff 1000). The active ultrafiltrate was further concentrated and desalted with an adsorptive microconcentrator, which adsorbs virtually all amino acids and peptides. Through this purification step, it was found that the adsorbed fraction obtained did not stimulate growth independently but acted complementarily with a small amount of ammonium sulfate. The adsorbed fraction was subsequently analyzed on reversed-phase high pressure liquid chromatography, and the activities of the eluates were measured on B12 assay medium with ammonium sulfate. Consequently, it was proved that several peptidic ingredients in the adsorbed fraction increased the growth of B. bifidum.

Ammonium Sulfate↗
PubMed2000

Purification and identification of a growth-stimulating peptide for Bifidobacterium bifidum from natural rubber serum powder.

Natural rubber serum powder, which is a by-product obtained in the production of latex rubber, has a strong growth-stimulating activity for Bifidobacterium bifidum JCM 1254. The retained fraction obtained by ultrafiltration (molecular weight cutoff 1000) showed a growth-stimulating activity in a dose-dependent manner on B12 assay medium with ammonium sulfate. One of the growth stimulators was purified from the retained fraction by acetone precipitation, solid-phase extraction with a hydrophobic pretreatment column, and multistage reversed-phase HPLC. An increase of 53-fold in the specific activity, and a recovery of 1.3% were obtained. The amino acid composition and N-terminal sequence analysis of this growth stimulator provided the structure of Ala-Thr-Pro-Glu-Lys-Glu-Glu-Pro-Thr-Ala. The molecular mass was 1075 by MALDI-TOF MS analysis. These results showed that this growth stimulator was a decapeptide with the sequence shown above. This is the first report that clarified the structure of an active peptide for the growth of Bifidobacterium.

Amino Acid Sequence↗
PubMed1976

Chronic diseases in the rubber industry.

An overview is presented of epidemiologic studies of chronic diseases in the rubber industry. Analyses of the mortality experience during the period 1964-1972 of workers age 40-64 and retirees age 65-84 of two large rubber and tire manufacturing companies consistently disclosed excesses of deaths attributed to leukemia and lymphosarcoma, and for cancers of the stomach, large intestine, and prostate. The relation of site-specific malignancies to work histories and grouped occupational titles as surrogate measures of work-related exposures to possible carcinogens is described. There was no evidence of company-wide, sizable, consistent excess for the other major chronic diseases causes of death. Although a total cohort deficit in the mortality rate for lung cancer was found, there was a history of increased frequency of exposure to certain work areas among lung cancer decedents. Morbidity studies, including analysis of disability retirements, and ad hoc questionnaire and health testing surveys, disclosed excesses of chronic pulmonary diseases. There was evidence of an interactive effect in the association of work and smoking histories with pulmonary disability retirement.

Adult↗
PubMed1976

Occupational disease in the rubber industry.

We have studied mortality patterns in a large cohort of rubber workers. We have examined workers exposed to curing fumes, processing dusts, and industrial talc and have begun to evaluate exposures of these workers in detail. Gastrointestinal (especially stomach) cancer appears in excess in processing workers. Lung cancer is excessive in curing workers. Leukemia is increased generally. All three groups studied for respiratory disease have an increase in disease prevalence which is related to intensity and duration of exposure. Since both an increase in stomach cancer and respiratory disease is seen in processing workers, exposures in this area must be controlled. Since both lung cancer and chronic respiratory disease is excessive in curing rooms, this exposure must be controlled. The leukemia risk is probably related to solvents. Whether this is all explainable by past benzene exposure is unknown. Further studies are planned to refine our knowledge concerning these risks so that occupational disease in the rubber industry can be prevented.

Adult↗
PubMed1976

Health aspects of the curing of synthetic rubbers.

A commonly used tread rubber formulation was cured in the laboratory under conditions simulating vulcanization in the Bag-O-Matic press. Volatile emissions were collected on charcoal and analyzed by combined GC-mass spectrometry. The compounds identified were either contaminants present in the raw material or reaction products. Some of these compounds were also identified in charcoal tube samples collected in the atmosphere of the industrial operations. Estimates based on the loss of weight of rubber during curing were used to predict airborne concentrations and compared to the concentrations actually found. The literature of the toxicity of raw materials and effluents was reviewed, and no acute or chronic toxicological effects would be anticipated. Information concerning potential carcinogenicity was not available and could not be evaluated.

Air Pollutants, Occupational↗
PubMed1996

Biological monitoring of genotoxic hazard in workers of the rubber industry.

Biological monitoring of genotoxic hazard in the rubber industry was performed in 19 male workers and 20 age-matched controls in a local health unit in northern Italy. Peripheral blood lymphocytes were analyzed for the presence of DNA damage (single-cell microgel-electrophoresis, or comet assay) and for cytogenetic parameters (sister chromatid exchanges and micronuclei frequency, and proliferative rate index). The following bioassays were performed in urine samples: a) mutagenicity test and concentration of thioethers as markers of exposure, and b) excretion of D-glucaric acid and 6-beta-hydroxycortisol (related to 17-hydroxycorticosteroid excretion) as indicators of the inductive status of the microsomal enzyme system (phase-I). The exposed subjects showed statistically higher mean values of 17-hydroxycorticosteroids and micronuclei and lower values of 6-beta-hydroxycortisol than controls, when taking cigarette smoking into account. The comet assay showed higher values for migration distance in exposed subjects than controls, although the differences were not significant at a p-value of 0.05. These findings suggest that industrial exposure in the rubber processing industry may cause genetic damage and may modify the activity level of some enzymes; these results should be considered with caution due to the small number of subjects enrolled.

Adult↗
PubMed1998

Natural rubber latex hypersensitivity: incidence and prevalence of type I allergy in the dental professional.

The authors investigated the prevalence of immediate (Type I) hypersensitivity to gloves made from natural rubber latex, or NRL, by performing skin-prick tests on 2,166 dental workers over the course of a two-year period (with two one-year intervals). The investigator used two separate eluents made from different brands of natural rubber latex gloves. The study, conducted in 1994 and 1995 as part of the American Dental Association's Annual Health Screening Program, found that 6.2 percent of the participants (dentists, hygienists and assistants) tested positive for Type I hypersensitivity to NRL proteins.

Adult↗
PubMed2000

Improved orthopaedic bone cement formulations based on rubber toughening.

Poly(methylmethacrylate) (PMMA) bone cements have been used for the fixation of hip and knee implants since the early 1960s. Aseptic loosening, related to fracture of the PMMA, continues to be the primary mode of failure for these prostheses. Failed prostheses must be replaced causing additional expense and patient trauma. Furthermore, the average lifetime of the revised prosthesis is significantly lower than that of a primary prosthesis. Recent work by Moseley and co-workers led to the development of a promising new rubber toughened cement. It is comprised of a matrix of the traditional PMMA with dispersed rubber particles to modify mechanical properties and, in particular, improve fracture toughness. The fracture toughness of the experimental material was 167% greater than the toughness of a nontoughened control; however, the elastic modulus and compressive strength were reduced. The reductions in properties should not pose a clinical problem based on results of the implant model reported by Moseley. More serious concerns were mixing and delivery problems and high residual monomer concentrations. The formulation and chemical/mechanical characterization of new toughened acrylic formulations that have residual monomer levels equivalent to Simplex and better mixing properties are reported.

Bone Cements↗
PubMed1981

Modeling of digestive tract lesions using silicone rubber RTV (KE-12).

In order to produce life-size models of digestive tract lesions, we applied silicone rubber RTV (KE-12) over the surface of the resected fresh, half-fixed or completely-fixed specimens to achieve their impressions. Into these impressions, super-hard plaster, acrylics and lysine base were separately poured, with the resultant casts realizing faithful replicas of the original patterns, finely reproducing their mucosal micro-structures. A photofluorogram of the silicone rubber pattern taken by using softex could reveal roentgenographic micromucosal features on a single plane. Clinically, endoscopic casting of lesions in similar procedures could produce their models, providing data available for estimation of the size and depth of an ulcer. Our method would be of help in dynamical pursuit of digestive tract lesions, as well as for comparison of the vital realities of lesions and their histopathological findings. The method may further contribute to reducing the dosage of x-ray bombardment in gastric fluoroscopy.

Animals↗
PubMed2003

Biomarker responses and chemical analyses in fish indicate leakage of polycyclic aromatic hydrocarbons and other compounds from car tire rubber.

Rubber tire material contains toxic compounds including oils rich in polycyclic aromatic hydrocarbons (PAH), so-called highly aromatic (HA) oils, as well as other reactive additives used as antioxidants, antiozonants, and vulcanization accelerators. The toxicity of rubber tire leachates to aquatic organisms has been demonstrated before. However, previous studies have focused on lethal rather than sublethal effects. We kept rainbow trout (Oncorhynchus mykiss) in tanks with two types of tires: a tire containing HA oils in the tread or a tire free of HA oils in the tread. After 1 d of exposure, an induction of cytochrome P4501A1 (CYP1A1) was evident in both exposed groups, measured as elevated ethoxyresorufin-O-deethylase (EROD) activity and increased CYP1A1 mRNA levels. After two weeks of exposure, EROD activity and CYP1A1 mRNA were still high in fish exposed to leachate from HA oil-containing tire, whereas the effect was somewhat lower in fish exposed to leachate from HA oil-free tread tire. Compounds in the tire leachates also affected antioxidant parameters. Total glutathione concentration in liver as well as hepatic glutathione reductase, glutathione S-transferase, and glucose-6-phosphate dehydrogenase activities were markedly elevated after two weeks of exposure in both groups. The responses were greater in the group exposed to leachate from HA oil-free tread tire. Vitellogenin measurements did not indicate leakage of estrogenic compounds from the tires. Chemical analyses of bile from exposed fish revealed the presence of hydroxylated PAH as well as aromatic nitrogen compounds indicating uptake of these compounds by the fish.

Animals↗
PubMedDate not supplied

Alternative rubber dam isolation technique for the restoration of Class V cervical lesions.

This article describes an expedited, atraumatic technique of restoring cervical abrasion-erosion, abfraction or carious lesions using an alternative placement sequence of the dental rubber dam for adequate field isolation. As shown by this technique, the rubber dam retainer is modified and positioned on the tooth with subsequent placement of the dental dam material over theretainer and tooth. This technique saves time and provides good retraction of the gingival tissue and isolation of the cavity preparation from contamination (saliva, hemorrhage) that can potentially cause post-operative symptoms and possible restoration replacement.

Dental Caries↗
PubMed1992

Carcinogens in rubber production in the Soviet Union.

In a preliminary phase of a broad research project on cancer among workers in a rubber footwear plant in Moscow, exposure to several known or potential carcinogens was assessed. There were high dust contents bearing both toxic substances and carcinogens. The highest concentrations of benzo[a]pyrene (500-14,400 micrograms) were found on the soot used as a filler, and the maximum N-dimethylnitrosamine (DMNA) level was measured in thiram (150-23,868 micrograms.kg-1). Air samples from the vulcanization process and the pressing of rubber goods showed BaP levels of up to 1.43 micrograms.m-3. In the work area where polyvinyl chloride was used, the mean vinyl chloride concentration was 0.21 (SE 0.06) mg.m-3. The mean value of the acrylonitrile concentrations in the workroom area was 0.19 (SE 0.07) mg.m-3. Very high levels of DMNA and N-diethylnitrosamine were measured in the preparatory shop in the winter.

Acrylonitrile↗
PubMed1983

Genotoxic hazards in the rubber industry.

The toxicology of chemicals used in the rubber industry is poorly known. In the present investigation an attempt was made to use biological monitoring methods to identify job categories with possible exposure to potentially genotoxic chemicals. Urine samples were collected and analyzed for mutagenic activity by the bacterial fluctuation test. The highest individual mutagenic activities were detected among the workers in the weighing and mixing departments, and some high individual values were found among vulcanizers. Sister chromatid exchanges (SCE) and structural chromosome aberrations were also analyzed from samples of peripheral blood. The effect of smoking was clearly associated with significantly increased numbers of SCEs and chromosome aberrations. Among the workers in different job categories, the highest SCE frequencies were found for mixers who smoked. Also nonsmoking cleaners of the mixing department differed significantly from the nonsmoking referents in this respect. However, only the group of nonsmoking weighers showed an increase in the number of chromosome aberrations (p less than 0.01) when compared with the referents. The results suggest the need for improved occupational hygiene in the weighing and mixing departments of rubber plants so that exposure to potentially hazardous genotoxic chemicals can be decreased.

Chromosome Aberrations↗
PubMed1976

[Detection of pentachlorophenol in natural rubber latex].

The method of detection of pentachlorophenol in natural rubber latex is proposed. Pentachlorophenol is isolated from other nonrubber-like substances by thin-layer chromatography and identified by spectroscopic method in UV-light. Isolation of pentachlorophenol is carried out from water extracts obtained from the dry caoutchouc films, so the same method can be used for examination of the rubber articles designed for the medicinetoo.

Chlorophenols↗
PubMed1994

The hydration phenomenon in natural rubber latex gloves and its effect on electronic glove monitors.

A physical model is presented to explain the phenomenon of hydration in natural rubber latex (NRL) gloves and to account for the observed decrease in electrical resistance of these gloves when exposed to normal saline solution. Microporosity in the rubber is attributed to failure of all latex particles making up a typical glove to completely coalesce with each other and form a continuous film free of interstitial voids. Native proteins and chemicals used in the manufacturing process are suspected of inhibiting coalescence and causing allergic reactions to some wearers after repeated uses. The effect of hydration on the performance of electronic glove monitors is discussed. Glove monitors that can distinguish between hydration and holes are considered to be the most reliable.

Electric Impedance↗
PubMed1998

Natural rubber-containing medical devices; user labelling--FDA. Final rule; interpretation.

The Food and Drug Administration (FDA) is providing notice that it does not intend to apply to combination products currently regulated under human drug or biologic labeling provisions its September 30, 1997, final rule requiring certain labeling statements for all medical devices that contain or have packaging that contains natural rubber that contacts humans. FDA is taking this action, in part, in response to a citizen petition and other communications from industry that the agency has received since the publication of the final rule. FDA intends to initiate a proceeding to propose natural rubber labeling requirements for drugs and biologics, including combination products that are currently regulated under drug and biologic labeling provisions. Such a proceeding may include a combination of rulemaking and guidance and will offer opportunity for public comment.

Consumer Product Safety↗
PubMed1998

Amended economic impact analysis of final rule requiring use of labeling on natural rubber containing devices--FDA. Final rule; amended economic analysis statement.

The Food and Drug Administration (FDA) is issuing an amended economic analysis statement relating to a final rule that published in the Federal Register of September 30, 1997 (62 FR 51021), requiring labeling statements concerning the presence of natural rubber latex in medical devices. This rule was issued in response to numerous reports of severe allergic reactions and deaths related to a wide range of medical devices containing natural rubber. The final rule becomes effective on September 30, 1998. In order to allow further comment on the economic impact of the September 30, 1997 final rule, FDA is publishing an amended economic impact statement, including an amended initial regulatory flexibility analysis (IRFA) that it has prepared under the Regulatory Flexibility Act (RFA), as amended by the Small Business Regulatory Enforcement and Fairness Act (SBREFA). FDA will respond to comments to this amended economic analysis statement, and publish in the Federal Register an amended final economic impact statement prior to the effective date of the September 30, 1997 rule.

Consumer Product Safety↗