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PubMed2005

Prevalence of type I natural rubber latex allergy among dental hygienists.

PURPOSE: Oral health care professionals have been shown to be at risk for developing a type I allergy to natural rubber latex (NRL). The objective of this study was to assess the prevalence of this allergy in dental hygienists. METHODS: Participants attending the 2000-2002 American Dental Hygienists' Association (ADHA) national meetings were screened for type I allergies to NRL using skin prick testing, symptom assessment, and health history. Participants were classified as positive for a type I NRL allergy based on their positive skin prick reactions to standardized NRL solutions. Risk factors and symptom assessments were based on a self-reported health history. RESULTS: Of the 582 ADHA participants who completed the screening and health history questionnaire, 4.8% (n=28) screened positive for a type I allergy to NRL (SPT-positive). These SPT-positive participants were significantly more likely to report an allergy to cross-reacting foods, plants, molds, and pollens, and to report reactions to rubber products. Participants screened SPT-positive were also significantly more likely to report a history of hives and respiratory symptoms after contact with natural rubber. CONCLUSION: Based on skin prick testing, the prevalence of a type I allergy to NRL in dental hygienists appears similar to that reported for other oral health care professionals and is greater than the general population. Educating dental hygienists about type I NRL allergy may help reduce prevalence and improve its management.

Adult↗

PubMed2006

[Canopy rainfall storage capacity of tropical seasonal rainforest and rubber plantation in Xishuangbanna].

Based on the 2003-2004 laboratory and field observation data, and with scaling-up method, this paper studied the canopy rainfall storage capacity of tropical seasonal rainforest and rubber plantation in Xishuangbanna. The results showed that the canopy rainfall storage capacity was 0.45-0.79 mm for tropical seasonal rainforest and 0.48-0.71 mm for rubber plantation, and that of the branch and bark accounted for >50 % of the total. For these two forests, the canopy rainfall storage capacity was much higher in foggy season (from November to February) and dry-hot season (from March to April) than in rainy season (from May to October), and the duration needed to reach water saturation was about 5 min for leaf, 2-3 h for bark, and 2. 5-4 h for branch. During the processes of wetting and air-drying, leaf was easier while branch and bark were somewhat difficult to hold water and then be air-dried, suggesting that leaf played an important role in intercepting rainfall in short-duration rainfall events, while branch and bark could work much better in doing this in long-duration or high-intensity rainfall events. Compared with rubber plantation, tropical seasonal rainforest had a stronger rainfall-storage capacity due to its multi-layer structure of canopy and excellent water-holding performance.

China↗

PubMed1989

[Type I allergy to rubber gloves containing latex].

We report on a 23-year-old female patient showing anaphylactoid mucosal reactions when handling Latex rubber gloves. Usually, type I intolerance against rubber gloves is due to allergy against Latex mediated by IgE. In addition, we discuss some general allergologic problems regarding the handling of rubber gloves.

Adult↗

PubMed1988

[Investigations on the tissue compatibility of silicon rubber materials using experimental animals].

The reaction of subcutaneous tissue in guinea-pigs at implants of six kinds of silicone rubber materials (VEB Chemiewerk Nünchritz) was investigated by semiquantitative and quantitative methods. These based on the "Programme to the Assessment of Subcutaneous Tissue Reactions at Implants" by Knöfler, Keller etc. The histocompatibility of the tested materials can be compared with that of titanium. One of the silicone rubbers differs from both the reference material and the other silicone rubber materials significantly and is assessed to be more suitable than the alloy Gisadent KCM 83 (chromium cobalt molybdenum alloy).

Animals↗

PubMedDate not supplied

Enhanced albumin affinity of silicone rubber.

The authors have developed a method to increase the albumin affinity of silicone rubber-containing medical devices. A vinyl-methyl silicone co-monomer was hydroxylated via an oxymercuration-demercuration reaction and then film-coated on a silicone rubber sheet. C16 acylation of the -OH coated sheet was carried out by an esterification reaction catalyzed by 4-DMAP. FTIR spectroscopy confirmed the presence of -OH groups following the hydroxylation reaction, and (CH2)n groups following the acylation reaction. 125I-labeled albumin binding studies indicated graded enhancements, according to reagent concentration, with maximal 2.7X and 2.5X increases for 20% -OH coated and 20% -OH/C16 acylated surfaces, respectively. Incubation with a protein denaturant, sodium dodecyl sulfate (SDS), removed 73% of adsorbed albumin from unmodified controls, with only 25 and 34% removal from 20% -OH coated and 20% -OH/C16 acylated surfaces, respectively. These results suggest that -OH and C16 modified surfaces not only preferentially adsorb albumin, but also retain it in a more stable configuration; this is an unexpected finding for -OH modified surfaces. Based on similar albumin affinities for biocompatible C18 alkylated and C16 acylated polyether polyurethanes, the authors expect significant improvements in thromboresistance and complement-activating potential for this modified silicone rubber.

Acylation↗

PubMed1986

Silicone rubber replacement of the severely fractured radial head.

Ten patients, at an average of 3.4 years after Swanson silicone rubber radial head replacement following acute trauma, were evaluated for pain, motion, and grip strength. Three had excellent results, one had a fair result, and two had poor results. Three patients had arthritis at the distal radioulnar joint. The arthritis was correlated with a positive ulnar variance in the uninjured wrist. Degenerative arthritis at the elbow was present in 56% (five out of nine). Ulnar variance was increased significantly in the wrists on the injured side, compared with the opposite wrist and to a control group. A 20-kg grip stress radiograph analysis showed the silicone rubber prostheses to deform and wrist subluxation to occur. A biomechanical study of six human cadaver upper extremities indicated that the flexible implants transferred minimal forces across the radiocapitellar joint. A radial head replacement with a modulus of elasticity similar to bone showed a more physiologic loading at the elbow. Both the clinical and biomechanical studies indicated that the silicone rubber prostheses is unable to transmit physiologic forces from the proximal radius to the capitellum. A less flexible radial head prosthesis should provide more normal physiologic stresses and may lead to improved clinical results.

Biomechanical Phenomena↗

PubMed1984

Flammability of silicone rubber: an unrecognized hazard.

A patient sustained a burn when silicone rubber tubing was ignited by a pencil cautery unit. Unlike polyethylene, silicone rubber does not melt prior to reaching its ignition temperature. The application of heat near or to silicone rubber is to be avoided.

Burns↗

PubMed1983

Three year follow-up study on the treatment of first and second degree hemorrhoids by sclerosant injection or rubber band ligation.

Two groups of 18 patients undergoing sclerosant injection or rubber band ligation for first or mild, second degree hemorrhoids have been followed-up at three years after the initial treatment. Following sclerosant injections, four of 18 patients initially presenting with bleeding per rectum did not have further episodes of bleeding within the three year follow-up period compared with 13 of 17 treated with rubber band ligation. The other symptoms of pain or discomfort, pruritus ani and soiling were not present with sufficient frequency to allow specific evaluation. Results of this study demonstrate that rubber band ligation produces better long term results than does sclerosant injection in treating bleeding, the principal symptom, of first and mild, second degree hemorrhoids.

Adult↗

PubMed1982

[Can silicon diffusion from silicone rubber catheters cause urethral stricture?].

Silicon-leakage out of alloplastic Silicon containing implants induces myofibroblast proliferation and constricting scar tissue. Therefore the possible Silicon-leakage out of Silicon rubber Foley-Catheters was of major interest. This cathaters were often used after internal urethrotomies of recurrent urethral strictures. Pieces of Silicon rubber Foley-Catheters of 18 F, 2 cm in length, were implanted subcutaneously and intraperitoneally in rats. Using Scanning electron microscopy and EDXA (energy dispersiv x-ray microanalysis) Silicon could not be identified in tissues around the implants 6 and 12 weeks after implantation. Therefore Silicon-leakage out of Silicon rubber Foley-Catheters is not responsible for recurrent urethral strictures.

Animals↗

PubMed1994

Management of hemorrhoids by rubber band ligation.

This study discusses the management of hemorrhoids by rubber band ligation. It reviews 233 rubber band ligation procedures in 148 patients with symptomatic hemorrhoids performed over a 5-year period. 72% of the patients underwent a single rubber band ligation, 22% a double band ligation and 6% a triple band ligation in one session without anesthesia. A follow-up of 18 +/- 5 months was carried out. Only three patients required hospitalization for complications. One patient was admitted for bleeding and recovered with clot evacuation, bed rest and blood transfusion. Two patients developed a band related abscess that resolved with drainage. Twenty patients (13.5%) reported pain associated with the procedure. Four patients needed subsequent surgical hemorrhoidectomy. Long-term results were good in 81.2% of the patients. This report agrees with previously published series showing the efficacy and cost containment of hemorrhoidal ligation.

Adult↗

PubMedDate not supplied

Silicone rubber splinting for athletic hand and wrist injuries.

The use of a silicone rubber protective playing splint facilitates an athlete's continued or earlier return to sport participation following injury. The purposes of this paper are to review the literature and to describe the properties, fabrication procedures, and indications for use of the silicone rubber compound materials used to splint athletic hand and wrist injuries. In general, the use of silicone rubber protective splints for stable orthopedic hand and wrist injuries has been shown to be effective.

Athletic Injuries↗

PubMed1996

Inguinal lymph node foreign body granulomas after placement of a silicone rubber (Silflex) implant of the first metatarsophalangeal joint.

We describe a woman who developed foreign body granulomas 8 years after metatarsophalangeal (MTP) joint silicone rubber implantation for hallux rigidus. She developed overnight swelling and tenderness in the inguinal region on the ipsilateral side. Histological evaluation of the lymph node showed foreign body granulomas. Electron microscopy and dispersion x-ray analysis identified the foreign body material in the inguinal lymph node and fibrous capsule surrounding the implant as silicone. Foreign body granulomas of surrounding tissues and regional lymph nodes are infrequently reported postoperative complications in patients with small joint silicone rubber implants. A fractured or eroded implant surface attributed to wear is usually noted at prosthesis excision. Granulomas in normal or enlarged lymph nodes have been described in both symptomatic and asymptomatic patients, with intact or fractured prostheses. Many related joint and lymph node symptoms resolve with removal of the silicone rubber prosthesis.

Adult↗

PubMedDate not supplied

Pharmaceutical container/closure integrity. I: Mass spectrometry-based helium leak rate detection for rubber-stoppered glass vials.

The development of mass spectrometry-based leak detection for pharmaceutical container integrity was undertaken to provide an alternative to microbial challenge testing. Standard 10-mL vials were modified to contain pinholes (0.5 to 10 microns) by affixing micropipettes with epoxy into 2-mm vial side wall holes. The absolute leak rate was determined using vials that were sealed in a tracer (helium) environment with butyl rubber stoppers and crimps. Alternatively leak rates were determined using vials that were sealed in room air and exposed to tracer under pressure (charging or bombing). Tracer leak rates were measured with mass spectrometry leak rate detectors. The absolute leak rate was correlated the squared nominal leak radius which suggested that the mode of gas flow through the glass pipette leaks was more turbulent than viscous even at low leak rates typically associated with viscous flow. The minimum observed absolute leak rate was about 10(-6.6) std cc/sec and was likely due to helium permeation through the rubber stoppers. Heat-stressed rubber stoppers did not affect the baseline absolute leak rate. Adsorption of helium tracer to the test unit surfaces was found to confound baseline leak rate measurement reliability but was eliminated as a source of variation by exposing the test units to ambient air for > or = 12 hours. The absolute leak rate and the leak rate measured after charging were related in a mathematically predictable way.

Drug Packaging↗

PubMed1998

Contact urticaria from rubber gloves: an occupational skin disorder for health care workers.

Rubber allergy is an important occupational health problem for an increasing number of patients. It may produce a type I urticarial reaction, or more commonly, a type IV delayed eczematous dermatitis. The risk groups include health care workers, rubber industry workers, and children with spina bifida (meningomyelocele) and urogenital abnormalities. In this report, we describe a physician with a relevant history who was found to have type I hypersensitivity to rubber by prick test and use test. Our aim is to increase awareness among physicians, discuss diagnosis and management, and review the literature.

Adult↗

PubMedDate not supplied

Airborne exposures to PAH and PM2.5 particles for road paving workers applying conventional asphalt and crumb rubber modified asphalt.

Personal exposure monitoring was conducted for road paving workers in three states. A research objective was to characterize and compare occupational exposures to fine respirable particles (< 2.5 microns) and particle-bound polycyclic aromatic hydrocarbons (PAHs) for road paving workers applying conventional (petroleum derived) asphalt and asphalt containing crumb rubber from shredded tires. Workers not exposed to asphalt fume were also included for comparison (to support the biomarker component of this study). The rubber content of the crumb rubber modified (CRM) asphalt at the three study sites was 12, 15, and 20%. A comparison of some specific job categories from two sites indicates greater potential carcinogenic PAH exposures during CRM asphalt work, however, the site with the greatest overall exposures did not indicate any differences for specific jobs. A statistical analysis of means for fine particle, pyrene and total carcinogenic PAH personal exposure shows, with two exceptions, there were no differences in exposures for these three measurement variables. One site shows significantly elevated pyrene exposure for CRM asphalt workers and another site similarly shows greater carcinogenic PAH exposure for CRM asphalt workers. Conventional and CRM asphalt worker airborne exposures to the PAH carcinogen marker, BaP, were very low with concentrations comparable to ambient air in many cities. However, this study demonstrates that asphalt road paving workers are exposed to elevated airborne concentrations of a group of unknown compounds that likely consist of the carcinogenic PAHs benz(a)anthracene, chrysene and methylated derivatives of both. The research described in this article has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

Air Pollution↗

PubMed2026

A STORM-based protocol for nanoscale imaging and quantitative analysis of protein-associated and phospholipid-associated structures in natural rubber.

Stochastic Optical Reconstruction Microscopy (STORM) enables nanoscale mapping of molecular components beyond the diffraction limit; however, its reproducible implementation in hydrophobic polymer matrices remains challenging because fluorescence-labeling specificity, fluorophore photoswitching, three-dimensional localization, chromatic registration, and quantitative image analysis must be carefully controlled. This protocol presents a standardized experimental workflow for dual-color labeling, astigmatism-based three-dimensional STORM acquisition, and quantitative analysis of protein-associated and phospholipid-associated structures in natural rubber (NR). The workflow covers sample pretreatment, Cy5 NHS ester labeling of protein-associated primary amines, DiI labeling of phospholipid-rich domains, STORM imaging-buffer preparation, three-dimensional single-molecule localization, dual-channel registration, generation of standardized xy projections, aggregate-size analysis, and projected lateral spatial correlation assessment. Reproducibility is supported by defined acquisition and localization criteria, three independent sample preparations with at least five fields of view analyzed per condition, and unlabeled, single-color, dye-only matrix, and processing-associated Cy5 controls. Mean lateral localization precisions of 11.8 ± 2.3 nm for Cy5 and 13.5 ± 2.9 nm for DiI were obtained, while two-dimensional Fourier ring correlation analysis of the xy projections yielded effective lateral image resolutions of approximately 25 and 28 nm, respectively. Image-based particle segmentation and localization-coordinate-based density-based spatial clustering of applications with noise (DBSCAN) were applied to standardized xy projections as complementary quantitative approaches. Application of the protocol to untreated, centrifuged, and protease-treated NR samples demonstrated treatment-associated changes in the detected abundance and projected size distributions of protein- and phospholipid-associated aggregates, together with a non-monotonic change in their projected lateral spatial correlation. These observations describe alterations in nanoscale organization but do not, by themselves, establish stable protein-phospholipid complex formation. Unlike previous studies that primarily demonstrated the feasibility of STORM imaging in rubber materials, the principal contribution of this work is an end-to-end, step-by-step protocol incorporating defined controls, three-dimensional localization, image-quality metrics, chromatic-registration procedures, and complementary quantitative-analysis pipelines for non-expert users. The workflow may be adaptable to other hydrophobic polymers and soft-material systems after appropriate optimization and validation.

Rubber↗

PubMed2025

Loss and recovery dynamics of mitochondria in laticifer vessels of the rubber tree under repeated latex harvesting.

Natural rubber is harvested by periodically incising the laticifer vessels in the bark of rubber trees to release latex, the cytoplasm of laticifers. Although mitochondria are suspended in the cytoplasm and were expected to leak out, some earlier studies failed to detect their presence. In this study, we identified mitochondria and plastids in expelled latex using molecular methods and confocal microscopy, quantifying their abundance at 13 850 ± 800 mitochondria per microliter latex. Each tapping event released approximately 746 ± 35 mtDNA copies and 113 ± 7 mitochondria per laticifer cell (mean cell volume: 0.008134 μl). Individual mitochondria contained 6.7 ± 0.6 genome copies (mean ± SD), a value significantly higher than the 1.5 ± 0.2 mtDNA copies per mitochondrion observed in leaves. This suggests that laticifer mitochondria are primed for proliferation. We further investigated mitochondrial dynamics during tapping cycles by measuring temporal changes in concentration. Initial latex flow exhibited the highest mitochondrial concentration (18 749 ± 954/μl), which progressively decreased to 40% of the initial level (7542 ± 940/μl) within 30 min, likely due to dilution from water influx. Following latex vessel plugging, the mitochondrial population rebounded rapidly, surpassing the initial concentration by 1.4-fold within 3 days. Subsequent tapping cycles (second and third) exhibited similar mitochondrial loss and recovery trends, though recovery kinetics shifted from a linear (first cycle) to a logarithmic pattern. These results indicate that tapping stimulates mitochondrial proliferation and that laticifer mitochondria lack protective mechanisms comparable to those of the nucleus, resulting in their expulsion with latex during harvesting.

Hevea↗

PubMed1954

Biosynthesis of rubber.

The problem of how rubber is synthesized in the plant has been divided into two portions: (i) the nature of the monomer used and how this monomer is synthesized, and (ii) the nature of the polymerization reaction by which the monomer is transformed to rubber. With respect to the first, the monomer appears to be the 5-carbon branched-chain compound beta-methylcrotonic acid or a derivative thereof. This substance is synthesized in the plant from acetyl-coA. With respect to the second, no information is available, since polymerization of the 5-carbon monomer units to polymers has not yet been achieved outside the living plant.

Acetyl Coenzyme A↗