Pure and filler free silicone rubber biomaterial; a new concept in preparing silicone rubber.
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Biocompatible Materials↗
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Biocontrol Potential and Mechanism of Endophytic Bacillus velezensis WSR1 Against Rubber Tree Anthracnose.
Fungal leaf anthracnose, caused by Colletotrichum species, is a major leaf disease of rubber trees, significantly reducing global natural rubber yields. To explore sustainable and safe biological control strategies, eight bacterial strains were isolated from rubber tree tissues, demonstrating antagonistic activity against Colletotrichum pathogens (C. siamense and C. australisinense). Among these, WSR1 exhibited the most pronounced antifungal effect, with inhibition rates of 87.64 and 89.03% against C. siamense and C. australisinense, respectively. Genomic analysis identified WSR1 as Bacillus velezensis. In pot experiments, WSR1 exhibited preventive efficacy of 77.24 and 73.42% for C. siamense- and C. australisinense-induced anthracnose, respectively, with therapeutic efficacy of 42.28 and 45.57%. WSR1 compromised the integrity of the cell walls and membranes of both C. siamense and C. australisinense, while inducing reactive oxygen species accumulation within the hyphae. Additionally, WSR1 enhanced rubber tree resistance to anthracnose by activating defense-related enzymes, including phenylalanine ammonia-lyase, polyphenol oxidase, and peroxidase. Plate assays and genomic analysis revealed that WSR1 secretes fungal cell wall-degrading enzymes (cellulases, pectinases, and proteases) and siderophores. Furthermore, liquid chromatography-mass spectrometry and gene cluster analysis confirmed the synthesis of antagonistic secondary metabolites, such as surfactin, macrolactin H, and fengycin. This study represents the first identification of B. velezensis as a potential biocontrol agent against rubber tree anthracnose, offering a promising candidate for the eco-friendly management of rubber tree diseases.
C. australisinense↗
[Hypersensitivity to rubber].
Occupational contact dermatitis caused by rubber chemicals is described in two groups of patients. The first group consisted of personnel from the operating rooms of a university hospital. In 12 persons the contact allergic reactions appeared to be mainly due to rubber chemicals of the thiuram group of compounds. The second group consisted of cattle farmers. In 6 persons patch tests could be performed. The main cause of the rubber contact on the farms appeared to be the milking machine. The antioxydants in the heavy duty rubber of these machines are of the paraphenylenediamine group of compounds. Positive patch tests were found to N-phenyl-N' -cyclohexylparaphenylenediamine (CPPD) and to the closely related N-phenyl-N'-isopropylparaphenylenediamine (IPPD). Their use in rubber of milking machines in Europe is based on the german "Mitteilungen aus dem Bundesgesundheitsamt" which permits the incorporation of IPPD in these kind of rubber parts to a percentage of 1,5%.
Bandages↗
Biocompatibility of standard and silica-free silicone rubber membrane oxygenators.
Spiral coil membrane oxygenators made from either standard silicone rubber or silica-free silicone rubber were compared using three priming techniques. Standard priming, carbon dioxide priming, and denucleation priming were employed with each type of device. Four-hour venovenous membrane oxygenator perfusions were carried out on awake sheep anticoagulated with heparin. Virtually no differences were observed in any parameters measured between standard silicone rubber and filler-free silicone rubber membranes. Significantly greater platelet losses occurred during the first hour of perfusion with standard priming and with carbon dioxide priming than with denucleation priming, using either type of membrane. These experiments demonstrate that denucleation priming reduces platelet losses during extracorporeal membrane oxygenator perfusion, but that the use of filler-free silicone rubber does not improve the biocompatibility of the membrane.
Animals↗
Cancer mortality and morbidity among rubber workers.
Mortality and morbidity from cancer among a cohort of 13,570 white male rubber workers were examined. Each man worked for at least 5 years at the Akron, Ohio, plant of the B. F. Goodrich Company. The potential period of follow-up was from January 1, 1940 to June 30, 1976. Departmental work histories were based primarily on records maintained by Local no. 5, United Rubber Workers. The occurrence of cancer was measured by death certificates and by a survey of Akron-area hospital tumor registries from 1964 to 1974. Two types of analyses were made: 1) an external comparison of mortality rates of rubber workers versus rates of U.S. white males, and 2) an internal comparison of cancer morbidity rates among persons who were employed in various work areas of the plant. Excess cases of specific cancers (observed/expected numbers) among workers in specific work areas included: stomach and intestine: rubber making (30/14.4); lung: tire curing (31/14.1), fuel cells and/or deicers (46/29.1); bladder: chemical plant (6/2.4), and tire building (16/10.7); skin cancer: tire assembly (12/1.9); brain cancer: tire assembly (8/2.0); lymphatic cancer: tire building (8/3.2); and leukemia: calendering (8/2.2), tire curing (8/2.6), tire building (12/7.5), elevators (4/1.4), tubes (4/1.6), and rubber fabrics (4/1.1). Agents that may be responsible for these excesses were considered.
Adult↗
Bioprospecting microbial genomes to expand the biocatalytic toolbox of rubber oxygenases.
A set of rubber oxygenases was discovered through phylogenetic analysis and AI-based structural modeling of complexes of the putative enzymes with a substrate mimicking cis-1,4-polyisoprene. Sixteen candidate proteins were selected from thermophilic microorganisms, all sequence-related to the Latex clearing protein from Streptomyces sp. K30 (LcpK30). Sequence truncation and solubility tags were then evaluated to enhance protein expression, with the SUMO tag proving to be the most effective. Including LcpK30, nine heme-containing oxygenases were successfully expressed in E. coli NEB 10-beta cells, purified (35-157 mg L-1 yield) and characterized. Steady-state kinetics revealed significant rubber latex-degrading properties for six of them, with the truncated SUMO-fused LcpK30 (SUMO-LcpK30T) showing activity in agreement with literature. Notably, the catalytic efficiencies of all the expressed homologs lay within one order of magnitude and the oxygenase from Thermomonospora echinospora was found to be particularly promising in terms of activity, especially at high latex concentrations (more than 1% w/v). The analysis of reaction mixtures by both HPLC and HPLC-MS confirmed the oxidation of cis-1,4-polyisoprene to form the expected isoprenoid oligomers (n = 2-12), whose distribution was consistent with the usual endo-type cleavage pattern in all but one case. This bioprospecting effort afforded a platform of new rubber-degrading enzymes with diverse efficiencies and product profiles, capable of adapting to targeted applications.
Oxygenases↗
Bladder cancer in rubber workers. Do screening and doctors' awareness distort the statistics?
The use of recognised carcinogens in the rubber industry before 1950 led to the introduction of screening progammes offering urinary cytology to workers who had been exposed. Publicity given to the introduction of these programmes and to individual claims for compensation have increased medical practitioners' awareness of a relationship between work and the industry and the subsequent development of bladder cancer. In this study 27 rubber workers and 88 controls registered in 1966 and 1967 with bladder cancer have been followed. A comparison of their death-rates and of the relative frequency of bladder cancer recorded on the death certificates should indicate whether cytological screening or doctors' awareness might explain a recent rise in the bladder-cancer death-rate in this industry. Since the proportions of rubber workers and controls who died before 1976 were similar (74% and 73% respectively) and bladder cancer was mentioned with similar frequence on their death certificates (80% and 83% respectively) neither screening nor doctor's awareness would appear to have an important influence.
Adenocarcinoma↗
Rubber sump drainage of enterocutaneous fistulae.
Effective sump drainage of high enterocutaneous fistulae, together with alimentary rest and total parenteral nutrition, is now an integral part of the modern management of patients with this condition. The low tissue reactivity of the plastic and polymer materials currently used in most drainage tubes appears however, to be counterproductive to the establishment of a discrete fistula track and control of the fistula. A case is made for the use of red rubber sump drains for enterocutaneous fistulae. The greater tissue reactivity of rubber is reviewed and confirmed by animal experimentation. A method of rubber sump drainage of enterocutaneous fistulae developed during the management of 83 such fistulae is described.
Animals↗
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↗
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↗
Bile peritonitis after the use of latex rubber T-tubes.
Three cases of biliary peritonitis following the removal of a latex rubber T-tube from the common duct in the second postoperative week are reported. This is a well-recognized complication following the use of polyvinyl chloride T-tubes in biliary duct surgery, but its occurrence with latex rubber T-tubes is extremely uncommon.
Adult↗
Adhesion between copper-plated acrylic tray resin and a polysulfide rubber impression material.
The method of copper plating on acrylic resin was developed, and the bond strength to polysulfide rubber was measured in comparison with that of the adhesive coating. The bond strength with copper plating was greater than with adhesive coating. The specimens with adhesive coating failed due to a rupture occurring at the elastomer-adhesive interface, while those with copper plating had cohesive-adhesive failure. The method of copper plating on acrylic resin improved the adhesion between the polysulfide rubber and the custom-built acrylic resin tray.
Acrylic Resins↗
Silicone rubber band for laparoscopic tubal sterilization.
In 1974, Yoon and associates (Am J Obstet Gynecol 120:132, 1974) described a new approach in which laparoscopic tubal occlusion was accomplished by utilizing the silicone rubber band technique. Recognizing the great advantages of the new technique in eliminating potential thermal injury associated with electrocoagulation, the authors have utilized the Yoon silicone rubber band technique in these institutions over the past 20 months. Thus far the procedure has been performed in 304 patients without any major complications. In the hope of eliminating and/or reducing possible pregnancy-failure rates, in 110 cases. In addition to application of the silicone band, the tube within the band was transected with non-electrical Seigler biopsy forceps. This, we believe, should provide an interesting long-term comparative study.
Female↗
[Substitution of an injured finger joint by silicone rubber prosthesis].
Between 1973 and the first semester of 1975, on the injured and destroyed digital articulation 27 patients have been operated on by means silicon rubber prosthesis of Swanson type. The prosthesis plasty and the field of its use are shortly resumed, pointing out the importance of its adaptation on the injured articulation. The operative technique is described, as well as the results obtained and the aspects of the evaluation are discussed. The results obtained with the silicon rubber prosthesis are very promising. In the case of failure arthrodesis may be performed at any time.
Finger Injuries↗
[Studies on the cytotoxic action of various silicone rubber impression materials by means of cell culture (author's transl)].
Biological test of the silicone rubber impression materials was done by utilizing tissue cultures of L strain cells. Criteria for cytotoxicity were based upon response index in agar diffusion method which was determined by zone index and lysis index, and morphological observations of the cells. The materials used were chosen among those which were commercially available. Base material, catalyst, unset and set mixes of both materials were tested respectively. X-ray fluorescence analysis of the material was also performed. Following results were obtained. 1) Base material of all the materials showed zone index of a range between 11.8 mm and 18.6 mm. On the otherhand, lysis index was relatively small and minimum response index was 11.8 mm/8.6 mm. The cells appeared normal after cultivation with the base materials, though tissue culture medium became opaque due to dissolution of the base materials. It is revealed that the above results mean little cytotoxicity to the cells. 2) Catalyst, on the otherhand, yielded intense cytotoxicity. Minimum response index for the catalyst was 13.4 mm/14.8 mm. Morphological observation was parallel to the results of agar diffusion method. 3) Unset mixes also yielded intense to moderate cytotoxicity. 4) Set mixes showed a similar in level of cytotoxicity to the unset mixes. 5) X-ray fluorescence analysis of the materials revealed existence of such elements as Si, Sr, Sn, S, Cu and Fe. Moreover, Zn was found in materials A, B, C, D and E; P in materials A and B, and Pb in materials E and F. However, it was unable to show what compound was formed by these elements. It is expected that the present results could give a clue on animal experiments or clinical use from the view point of biocompatibility of silicone rubber impression materials.
Animals↗
Epidemiologic investigations of styrene-butadiene rubber production and reinforced plastics production.
The United States National Institute for Occupational Safety and Health (NIOSH) began an epidemiologic study of workers employed in the styrene-butadiene rubber (SBR) industry during 1976. This study was prompted by reports of relatively high numbers of leukemia deaths occurring within SBR production work populations. Simultaneous with the initiation of this investigation, the University of North Carolina released a report associating an excess risk of death due to hematopoietic and lymphatic malignancies among workers producing several synthetic rubbers, including SBR. This report presents NIOSH's preliminary mortality observations and a discussion of progress made on the analyses of contaminants found in two SBR production facilities. Currently, NIOSH is determining the feasibility of doing an epidemiologic study in the reinforced plastics industry. Interest in this study developed as part of an effort to determine health hazards associated with occupational exposure to styrene. Most of the technology for the reinforced plastics industry developed in the 1950s, and therefore this process represents a relatively new industry. This report also includes information on environmental conditions observed in the reinforced plastics industry and enumerates some of the complicating characteristics of this industry which increase the complexity of this study.
Bone Marrow Diseases↗
[Ambulatory hemorrhoidectomy through rubber band ligation-review of the literature].
The value of rubber band ligation in the treatment of haemorrhoids is discussed and the literature on the case histories of 3244 patients who were treated by this technique is reviewed. 36% of the patients found this form of therapy to be painless, 41% suffered little and 14% severe pain. 80% of all patients finally were free of symptoms. Rubber band ligation therefore is an effective method treating internal haemorrhoids. Its advantages are simplicity, relatively little discomfort for the patient, applicability in ambulant patients, no general anaesthesia, low cost and good results with only minor complications. Thus it is an alternative to sclerotherapy and to surgical haemorrhoidectomy.
Adolescent↗
Mutagenicity and metabolism studies on 12 thiuram and dithiocarbamate compounds used as accelerators in the Swedish rubber industry.
12 thiuram and dithiocarbamate compounds used in the rubber industry as accelerators, and to some extent as sources of sulfur, were tested, as well as carbon disulfide, a metabolite found in vivo after dithiocarbamate treatment, for mutagenicity in Salmonella typhimurium. A mutagenic effect on the base-substitution-sensitive strains TA1535 and TA100 was found for 7 compounds. The most potent directly acting mutagens were: tetramethylthiuram disulfide (TMTD), zinc dimethyldithiocarbamate (ziram), cadmium diethyldithiocarbamate and zinc diethyldithiocarbamate. Tetraethylthiuram disulfide (TETD), also known as Antabus, and carbon disulfide were non-mutagenic. The relatively low direct mutagenic effect of tetramethylthiuram monosulfide (TMTM) was enhanced in the presence of a metabolizing system (S9 mix). A hypothesis is given regarding the activation process of the monosulfide TMTM.
Animals↗