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PubMed1999

Analysis of odorous compounds in water by isolation by closed-loop stripping with a multichannel silicone rubber trap followed by gas chromatography-mass spectrometry.

An alternative technique for the isolation and concentration of odorous compounds found in potable water is described. The method currently employed by water authorities is closed-loop stripping with the collection of these substances on a small activated carbon filter. The compounds of interest are then extracted from the carbon using a suitable solvent. The authors offer a multichannel silicone rubber trap as an alternative to the carbon filter. The absorbed compounds are thermally desorbed from the trap, directly on to the gas chromatographic column for analysis by GC-MS, thereby eliminating the solvent extraction step required by the carbon filter. The multichannel silicone rubber trap, producing equivalent results, offers a number of advantages over the carbon filter.

Camphanes↗

PubMed1983

Blue Rubber Bleb Nevi as a cause of intussusception.

The Blue Rubber Bleb Nevus syndrome is a rare disease characterized by a distinctive type of hemangioma which involves the skin and the gastrointestinal tract. In the latter location, these lesions are often responsible for chronic blood loss and secondary anemia, and in rare situations may act as a leading point for an intussusception. The diagnosis of intussusception in children older than 3 or 4 yr is frequently difficult and delayed. In a child with typical skin lesions of the Blue Rubber Bleb Nevus syndrome, an acute illness with manifestations of intestinal obstruction should indicate the possibility of an associated intussusception.

Child↗

PubMed2000

The elicitin secreted by Phytophthora palmivora, a rubber tree pathogen.

Palmivorein, a new member of the elicitin family, was purified from the culture filtrate of Phytophthora palmivora isolated from the rubber tree, Hevea brasiliensis. The elicitin was obtained by ammonium sulfate precipitation and further purified using ion-exchange and gel filtration. The molecular weight, isoelectric point, amino acid composition and N-terminal sequences of this molecule are reported and compared to other known elicitins. Palmivorein, as determined by SDS-PAGE, is a small protein of M(r) ca. 10,000. It is classified as an alpha-elicitin according to its acidic pI and the valine residue at position 13. Like other elicitins, the P. palmivora elicitin causes tissue necrosis on tested tobacco leaves. It also causes severe wilting and necrosis of Hevea tissue, and leaves of the susceptible rubber clone (with respect to P. palmivora) are much more sensitive to this elicitin than those that are resistant.

Algal Proteins↗

PubMed1996

Latex allergen levels of injectable collagen stored in syringes with rubber plungers.

OBJECTIVES: To assess the latex allergen content of glutaraldehyde cross-linked injectable bovine collagen stored in rubber plunger syringes. METHODS: Extracts of syringe plungers and collagen solutions before and after storage in syringes with natural rubber latex plungers were tested for latex protein allergens. Thirty-nine patients known to be allergic to latex underwent skin prick testing with extracts of the latex plungers, collagen solutions before and after storage in syringes, standard latex skin test reagents, four extracts from commercially available gloves, and positive (histamine) and negative (diluent) control solutions. Thirty-one control patients not known to be latex allergic were similarly tested. RESULTS: No latex proteins were detected using in vitro immunochemical techniques. Only 1 of 39 (2.5%) latex allergic patients reacted to the syringe extract and the collagen stored in the syringe. No reactions were recorded to collagen that no contact with latex. CONCLUSIONS: The level of latex antigens in injectable collagen is very low. The low prevalence of skin test reactivity in these highly latex allergic individuals suggests that type 1 hypersensitivity reactions as a result of latex contamination would be unlikely.

Allergens↗

PubMed1998

IgE antibodies to prohevein, hevein, and rubber elongation factor in children with latex allergy.

BACKGROUND: Prohevein (Hev b 6.01) and hevein (Hev b 6.02) have been shown to be major IgE-binding allergens in health care workers and other adult patients allergic to natural rubber latex (NRL). Rubber elongation factor (REF; Hev b 1) and the 23/27 kd NRL allergen (Hev b 3) are characteristic of children with latex allergy who have spina bifida and other children requiring multiple operations at an early age. In addition, there are children with latex allergy and no history of multiple operations in whom sensitizing allergens are not known. OBJECTIVES: We studied IgE antibodies to NRL allergens in children with latex allergy who had not undergone surgery and compared the findings with those in children with latex allergy and a history of multiple operations. METHODS: Sera from 30 children with latex allergy who had not undergone surgery, 12 children with latex allergy with a history of multiple operations, and 19 control children without evidence of NRL allergy were examined. Immunoblotting was used to study IgE binding to NRL proteins, and purified prohevein, hevein, and REF were used in ELISA to measure specific IgE antibodies. RESULTS: In immunoblotting, sera from 21 (70%) children who had not undergone surgery and from 4 (33%) children with a history of multiple operations showed IgE binding to a 20-kd protein band (known to contain prohevein), and 9 (30%) and 8 (67%) sera, respectively, to a 14-kd protein band (known to contain REF). In ELISA, sera from 26 (86%) children who had not undergone surgery and from 7 (58%) children with a history of multiple operations had IgE antibodies to prohevein and 19 (63%) and 7 (58%) sera, respectively, to hevein. Eight (27%) sera from the children who had not undergone surgery had IgE antibodies to REF in contrast to 8 (67%) sera from children with a history of multiple operations. CONCLUSIONS: The IgE antibody pattern differs between children with latex allergy who had not undergone surgery and those with a history of multiple operations. The major allergens in children with no history of surgery appear to be prohevein and hevein and not REF, a finding that agrees well with that reported for health care workers with allergy to latex.

Adolescent↗

PubMed1998

Rubber latex allergy and the endodontic patient.

Increasingly, patients with rubber latex allergy are being seen in dental offices. Health care workers, persons allergic to certain foods and those with certain medical histories are potentially latex-sensitive. This article presents the case of a patient with a history of severe rubber latex allergy and the associated management of an endodontically involved tooth. The possibility of the latex allergic patient being sensitive to gutta-percha obturation material is also raised.

Adult↗

PubMed2000

Peripheral nerve regeneration using silicone rubber chambers filled with collagen, laminin and fibronectin.

A 10 mm gap of rat sciatic nerve was created between the proximal and distal nerve stumps, which were sutured into silicone rubber tubes filled with an extracellular gel containing collagen, laminin and fibronectin. Empty silicone rubber tubes were used as controls. Six weeks after implantation, all extracellular elements were completely degraded and absorbed, and 90% of the animals from the extracellular gel group exhibited regeneration across the nerve gaps, whereas only 60% in the control group. Both qualitative and quantitative histology of the regenerated nerves revealed a more mature ultrastructural organization with 28% larger cross-sectional area and 28% higher number of myelinated axons in the extracellular gel group than the controls. These results showed that the gel mixture of collagen, laminin and fibronectin could offer a suitable growth medium for the regeneration of axons.

Action Potentials↗

PubMed1997

Adhesion of Lactobacillus species in urine and phosphate buffer to silicone rubber and glass under flow.

Coating uroepithelial cells or catheter materials with lactobacilli has been shown to retard the development of a uropathogenic biofilm, with biosurfactant production and strong adhesion being two prerequisite properties of the Lactobacillus strains to be employed. In this paper, adhesion of six selected Lactobacillus strains to silicone rubber and glass in urine and in a phosphate buffer was studied using a parallel plate flow chamber. In addition, adhesive cell surface properties of the lactobacilli, i.e. the pH dependences of their zeta potentials and their hydrophobicities by water contact angles, were determined. L. acidophilus ATCC 4356 and L. fermentum B54 were the only strains showing significant adhesion to both hydrophobic silicone rubber and hydrophilic glass, possibly by virtue of their high cell surface hydrophobicities (water contact angles of 68 and 75 degrees, respectively) and small zeta potentials (-10.0 and -8.1 mV in buffer, respectively). Both hydrophobic Lactobacillus strains adhered less well in urine than in buffer. The remaining Lactobacillus strains studied were hydrophilic, with water contact angles between 25 and 36 degrees, and had highly negative zeta potentials, reaching -37.7 mV in buffer. Adhesion of these highly negatively charged, hydrophilic strains in buffer was essentially absent, while for some of these strains minor adhesion in urine was observed. This study demonstrates that the adhesion of lactobacilli to substrata differs with strain hydrophobicity and charge, and that urinary components can affect the ability of hydrophilic Lactobacillus strains to adhere to substrata.

Adult↗

PubMed2002

Bilateral multifocal hemangiomas of the orbit in the blue rubber bleb nevus syndrome.

PURPOSE: To report the clinical findings and surgical treatment of multifocal, bilateral orbital hemangiomas in a patient with the blue rubber bleb nevus syndrome, a rare vascular disorder characterized by distinctive cutaneous and visceral hemangiomas. DESIGN: Interventional case report. METHODS: Review of clinical findings, radiologic studies, and treatment of the patient. RESULTS: A 36-year-old female with multifocal, bilateral orbital lesions was seen with severe proptosis and decreased visual acuity of the left eye. Surgical debulking of multiple cavernous hemangiomas of the orbit resulted in decreased proptosis and an improvement in visual acuity. Subsequent histopathologic analysis and the results of a systemic workup revealing multiple, distinctive, cutaneous and visceral lesions were found to be consistent with the blue rubber bleb nevus syndrome. CONCLUSIONS: Although hemangiomas of the orbit are relatively common occurrences, multifocal, bilateral lesions may exist in the setting of underlying systemic hemangiomatosis. Bilateral or multifocal hemangiomas associated with cutaneous or visceral lesions should alert the clinician to the possibility of a number of syndromes that may have life-threatening consequences.

Adult↗

PubMed2000

Fatal suffocation by rubber balloons in children: mechanism and prevention.

This paper presents five autopsy cases of children who died as a result of an accidental choking on latex (rubber) balloons. All of the investigated cases suffocated by an intact (non-broken), pear-shaped and medium-sized balloon of less than 9 cm in length and 4 cm in width. The mouthpieces of all the involved balloons were upward and above the vocal cords, while the nosepieces were downward in the larynx and the trachea. The application of continuous suction forces to uninflated or partially air-filled balloon is considered the most crucial factor in causing asphyxiation by rubber balloon. An uninflated balloon is usually placed outside the mouth cavity where the child sucks the balloon into the mouth, either during a repeated trial of inverting the balloon inside-out or during the application of a direct suction to their bulb. A partially air-filled balloon is usually placed inside the mouth cavity then it is pushed further inside by movements like sucking or chewing. Other important factors are a sudden slippage of the mouthpiece from the fingers or teeth of the child, as well as the panic of the suffocation. The process of suffocation is also facilitated by the counterforce, which results from a sudden pressure of the mouth cavity over the bulb of the balloon, and the consistency of the balloons as pliable objects. Once the balloon enters the airway, it is less likely to be expelled. Supervision of children by adults and proper education programs are needed to decrease this problem.

Airway Obstruction↗

PubMed2002

Diagnosis of natural rubber latex allergy.

The accurate diagnosis of a latex-allergic individual begins with a comprehensive clinical history. Atopy, food allergies, hand dermatitis, and temporal relationships between allergic symptoms and natural rubber product exposure are risk factors that increase the suspicion of latex allergy. If symptoms are temporally delayed (hours-days) and confined to skin-latex product contact areas, Type IV hypersensitivity should be suspected and patch testing may be performed to identify activated T cells that are specific for selected rubber chemical additives. If ocular, upper and lower airway, and/or systemic allergic symptoms are observed with rapid onset (minutes) following a definable latex exposure, Type I hypersensitivity should be suspected. One or several confirmatory tests for latex-specific IgE antibody in the skin or blood may next be performed to verify a sensitized (IgE antibody positive) state. If the clinical history remains discordant with a skin test or blood test result, in vivo provocation tests may be cautiously considered for adjudication. Diagnostic methods for latex-specific IgE antibody detection in skin and blood are overviewed, with a focus on their performance, advantages, and limitations.

Humans↗

PubMed1997

The silicone rubber contact lens: clinical indications and fitting technique.

Although the silicone rubber contact lens (SRCL) is not used frequently, there area number of clinical indications for its use which include paediatric and adult aphakia, decompensated cornea, dry eye, irregular cornea, eyelid defects, corneal ulcer and corneal perforation. The properties of silicone rubber are reviewed and the fitting technique of the SRCL is described.

Journal Article↗

PubMed2004

Liquid chromatography/coordination ion spray-mass spectrometry for the analysis of rubber vulcanization products.

Liquid chromatography/coordination ion spray-mass spectrometry has been used for the identification of reaction products in a model rubber vulcanization process. After LC separation using reversed-phase conditions, AgBF(4) in acetonitrile was added, and strong signals were observed for silica-rubber coupling agents and products of the reaction between these and alkenes. The method performs best for substances containing sulfur chains with chain lengths between two and eight sulfur atoms, but sulfur-free compounds containing triethoxysilyl groups were detected as well. For the latter, the postcolumn addition of NaBF(4) proved to be a suitable alternative. Besides the coupling agents, various reaction products, including sulfur-chain bridged alkenes were identified.

Journal Article↗

PubMed2005

Whole range of chain dynamics in entangled polystyrene melts revealed from creep compliance: thermorheological complexity between glassy-relaxation region and rubber-to-fluid region. 1.

The rubber(like)-to-fluid region of the creep compliance J(t) results reported by Plazek of two nearly monodisperse polystyrene melts in the entanglement region have been quantitatively analyzed in terms of the extended reptation theory (ERT), giving the frictional factor K (= zetab2kTpi2m2) in quantitative agreement with the values obtained previously from analyzing the relaxation modulus Gt line shapes as well as calculated from the viscosity and diffusion data-a quantity shown independent of molecular weight as expected from the theory. Using the successful description of Jt in terms of ERT in the rubber(like)-to-fluid region as the reference frame in time, the glassy-relaxation process microG(t) that occurs in the small-compliance short-time region of J(t) can be studied in perspective. As shown from the analysis in terms of a stretched exponential form for microG(t) incorporated into ERT, the temperature dependence of the energetic interactions-derived microG(t) process being stronger in a simple manner than that of the entropy-derived ERT processes accounts fully for the uneven thermorheological complexity occurring in J(t) as initially observed by Plazek. When the results of analysis being displayed in the G(t) form, the relative roles of the energetic interactions-derived dynamic process and the entropy-derived ones in polystyrene are clearly revealed. It is shown that at the calorimetric glass transition temperature (Tg) the contribution from energetic interactions among segments to G(t) at the time scale of the highest Rouse-Mooney normal mode greatly exceeds that derived from entropy, indicating vitrification at the Rouse-segmental level. At the same time the Rouse-Mooney normal modes provide an internal yardstick for estimating the characteristic length scale of a polymer at Tg, giving approximately 3 nm for polystyrene. On the basis of the obtained results, the basic mechanism for the thermorheological complexity occurring in polystyrene is analyzed. It is shown that this basic mechanism should be also responsible for the breakdown of the Stoke-Einstein equation in relating the translational diffusion constant and viscosity as observed in glass-forming liquids, such as OTP and TNB, in approaching Tg from above.

Journal Article↗

PubMed2006

Surface modification of EPDM rubber by plasma treatment.

The effect of argon, oxygen, and nitrogen plasma treatment of solvent cast EPDM rubber films has been investigated by means of atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and surface energy measurements. Plasma treatment leads to changes in the surface energy from 25 to 70 mN/m. Treatment conditions influenced both the changes in surface energy and the stability, and it became more difficult to obtain good contact angle measurements after longer (> ca. 4 min) treatment times, probably because of an increasingly uneven surface structure. XPS analyses revealed that up to 20 at. % oxygen can be easily incorporated and that variations of approximately 5% can be controlled by the plasma conditions. Oxygen was mainly found in hydroxyl groups, but also as carbonyl and carboxyl. XPS analyses showed more stable surfaces than expected from contact angles, probably because XPS analysis is less surface sensitive than contact angle measurements. AFM measurements revealed different surface structures with the three gases. The surface roughness increased generally with treatment time, and dramatic changes could be observed at longer times. At short times, surface energy changes were much faster than the changes in surface structure, showing that plasma treatment conditions can be utilized to tailor both surface energies and surface structure of EPDM rubber.

Journal Article↗

PubMed2001

Frequency of natural rubber latex allergy in adults is increased after multiple operative procedures.

BACKGROUND: It has been shown that immediate-type allergy to natural rubber latex (NRL) affects predominantly health-care workers and infants with malformations requiring repeated medical procedures. Adult patients with multiple invasive procedures are not thought to be at an increased risk of NRL allergy. METHODS: A total of 325 consecutive adult inpatients (54.4+/-15.6 years; 219 men, 106 women) awaiting surgical or urologic procedures were assessed by questionnaire-based history (atopic diseases, number of previous standard operative or endoscopic procedures, intolerance to rubber products, and adverse reactions during medical care), by skin prick tests with different NRL test solutions, by measurement of NRL-specific IgE in the serum, and, if sensitization to NRL was found, by cutaneous challenge tests with NRL-containing material. Subjects were classified as sensitized to NRL if skin prick test reactions to NRL were positive or if NRL-specific IgE antibodies were found. NRL allergy was defined as NRL sensitization and immediate-type symptoms to NRL. RESULTS: Thirty-one of 325 (9.5%) subjects were found to be sensitized to NRL, 14/285 (4.9%) by skin prick testing and 23/323 (7.1%) by NRL-specific IgE antibodies in the serum. Four individuals (1.2%) were diagnosed as having clinically manifest NRL allergy, and another 27 (8.3%) were sensitized to NRL without symptoms to date. The frequency of previous invasive procedures was zero in eight patients, up to 10 in 245, 11-20 in 52, 21-30 in seven, and over 30 (up to 83) in 13 patients. No association was found between the number of invasive procedures and NRL sensitization without clinical symptoms. However, 3/4 patients with NRL allergy had undergone more than 30 interventions, and 1/4 had had 11 operations. Frequent invasive procedures (more than 10) were significantly associated with NRL allergy (P<0.001). Allergy or sensitization to NRL was associated with atopy (21/31 vs 87/294) (P<0.001). CONCLUSIONS: A remarkable percentage of unselected adult patients undergoing surgical procedures have allergy or sensitization to NRL. Repeated invasive treatment appears to be a risk factor for NRL allergy.

Adult↗

PubMed1986

Contraction and relaxation of cultured mesangial cells on a silicone rubber surface.

Glomerular mesangial cells (MC) in culture are believed to contract or relax in response to agents such as angiotensin II and cyclic AMP. However, cells grown on glass or plastic surfaces are limited in their response to vasoactive agents because of the rigid surfaces to which they adhere; thus, interpretation of a change in shape as contraction, relaxation, or detachment is difficult. We have grown MC on a flexible silicone rubber (dimethylpolysiloxane) substrate (DMPS), and studied with sequential photographs several models of cell contraction, relaxation, and detachment. When the cells contracted, the DMPS became wrinkled; when the cells relaxed, the DMPS lost wrinkles. In contrast, if the cells detached, the sheet lost wrinkles as the cells became smaller and rounder. Angiotensin II (5 X 10(-7) M), and calcium ionophore A23187 (2 X 10(-6) M) increased wrinkles in more than 30% of cells at 22 degrees C and more than 40% of the cells at 36 degrees C. The earliest effect was visible within five to 10 minutes at 22 degrees C and within one minute at 36 degrees C and increased until 40 minutes; thereafter, the cells relaxed and wrinkles were reduced. 10(-1) M Na azide prevented the increase in wrinkles produced by angiotensin II. Seventy-two percent of the angiotensin II-treated cells whose margins could be seen in their entirety, and 78% of the calcium ionophore-treated cells showed a reduction in surface area at a time when new wrinkles were appearing or wrinkles were increasing in size. Dibutyryl cyclic AMP, a known smooth muscle relaxant, produced a decrease or loss of wrinkles in 90% of the cells, and an accompanying increase in surface area. Untreated control cells, observed in conjunction with the above series, showed little change in wrinkles. Ten percent DMSO, an actin-translocating agent, produced a reversible disappearance of wrinkles. These models of contraction and relaxation could be distinguished from cell detachment; EDTA, for example, in the presence of zero calcium, diminished both cell size and wrinkles, with an accompanying lifting of cells from the surface. Similar results were obtained with cytochalasin B and chlorpromazine. Thus, the silicone rubber system accurately reflects the contraction, relaxation and detachment of cultured mesangial cells in response to a variety of agents.

Angiotensin II↗

PubMed1989

Desmond Greer Walker Award. Rubber dam acceptance.

Probably no other technique or instrument used in dentistry is so universally accepted and advocated by the recognised authorities and so universally ignored by the practising dentists, as the rubber dam. According to the 1983 Survey by the British Endodontic Society, only 5% of the dentists working principally in the National Health Service in England used rubber dam for endodontic treatment. Presumably this figure is even lower for non-endodontic procedures.

Adolescent↗