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At least 433 records · Page 24Linked to original sources
PubMed1981

Use of silicone rubber as a pericardial substitute to facilitate reoperation in cardiac surgery.

Reoperations following cardiac procedures have an increased risk because of the danger of damaging the heart, great vessels, or grafts because of adhesions to the sternum and anterior chest wall. We report our experience with the use of silicone rubber as a pericardial substitute in 102 patients--58 children undergoing palliative and corrective operations and 44 adults undergoing porcine valve insertion or coronary revascularization. The pericardial substitute was used only in cases in which reoperation was considered likely. There were no mediastinal infections. One adult had signs of cardiac constriction which improved markedly on administration of anti-inflammatory agents. Seven patients required reoperation for bleeding. Two patients who underwent Fontan procedures developed pericardial effusions necessitating a pericardial window. Reoperation was undertaken 1 to 12 months postoperatively in seven patients, all of whom were children. The silicon rubber greatly facilitated opening of the chest bone but did not affect the formation of adhesions within the pericardium. Postmortem examinations have been obtained in two cases 5 and 9 months postoperatively, and showed a thin layer of dense fibrous tissue adjacent to the silicone rubber. We conclude that silicone rubber may be used as a pericardial substitute and that it facilitates reoperation following cardiac operations. Particular caution should be used in patients undergoing Fontan procedures, as there appears to be a tendency for pericardial effusions and tamponade to develop.

Adult↗
PubMed1975

[Macroscopic and microscopic study of local compatibility of silicone rubber in short- and long-term experiments].

Extended trials were carried out on the purpose of finding optimal silicone rubber materials for endotheses, among others macroscopical and microscopical examinations of local compatibility after implantation in rats and dogs. Short-term experiments on 7 kinds of silicone rubber (VEB Chemiewerk Nünchritz) showed that subcutaneous and intramuscular implantation was well tolerated by rats. Optimal terms for removal were the 7th and the 28th day. Long-term trials of 4 kinds of silicone rubber in rats and dogs up to 1 year yielded no significantly different results compared with control materials from the Dow Corning Corporation. After comparing trials for biostability, 2 silicone rubbers were recommended for clinical use. Optimal terms for removing in long-term experiments were the 3rd, 6th, and 12th month. In the rat experiments after 6 months the thickness of the capsule remained constant, as morphometrically determined. This might be crucial in the assessment of long-term compatibility.

Animals↗
PubMed1994

Hevein, a lectin-like protein from Hevea brasiliensis (rubber tree) is involved in the coagulation of latex.

Hevein, a lectin-like protein is the major protein of vacuolar structures called lutoids in the latex of rubber trees. We have shown both by in planta and ex planta studies that hevein is involved in the coagulation of latex by bringing together rubber particles. This polyvalent bridging between hevein and rubber particles is mediated by N-acetyl-D-glucosamine and involves a receptor glycoprotein of 22 kDa, which is localized on the surface of the rubber particles. The proposed role of hevein helps us to understand the mechanism of coagulation of latex and assigns a physiological intracellular function to one of the smallest lectins.

Acetylglucosamine↗
PubMed2026

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↗
PubMed1999

Elevated mortality from nonalcohol-related chronic liver disease among female rubber workers: is it associated with exposure to nitrosamines?

BACKGROUND: Despite several case reports describing liver toxicity of nitrosamines and the fact that some N-nitroso compounds are used to induce cirrhosis of the liver in animal models, this association has not been investigated in epidemiological studies. METHODS: A cohort of 2,875 female rubber workers who were active on January 1, 1976, or hired thereafter, and who had been employed for at least 1 year in one of five plants producing tires or technical rubber goods was followed for mortality from January, 1976, through December, 1991. Work histories were reconstructed using routinely documented "cost center codes" and classified into six work areas. Age and calendar year standardized mortality ratios (SMR) and 95% confidence intervals (95% CI) were calculated and stratified by plant, work area, year of hire, and years of employment in the respective work area. RESULTS: The excess mortality from cirrhosis of the liver was most pronounced for nonalcohol-related cirrhosis of the liver (ICD-9 571.4-571.9: 10 deaths, SMR 202; 95% CI 97-372). Mortality from alcohol-related cirrhosis of the liver (ICD-9 571.0-571.3: 3 deaths, SMR 153; 95% CI 31-446) and from other alcohol-related diseases (organic psychoses, injury, and poisoning) was not statistically significantly elevated. All 10 cases of nonalcohol-related cirrhosis had worked in production of technical rubber goods (SMR 279; 95% CI 134-514) and risks increased with earlier years of hire and with longer duration of employment in this work area. DISCUSSION: Although our results must be interpreted with caution, they suggest that the observed excess deaths from cirrhosis of the liver are associated with occupational risk factors. In light of additional evidence from case reports and animal data, exposure to nitrosamines may be a plausible risk factor for the observed excess mortality.

Adult↗
PubMed1982

A case-control study of employment experience and lung cancer among rubber workers.

In this case-control study the detailed employment histories of 121 rubber plant employees who died of lung cancer from 1964 through 1973 were compared to those of 448 plant employees (controls) who died of other causes during the same calendar period. All subjects were white male hourly employees. Lung cancer cases and controls were matched individually on year of birth and year of first hire at the plant. Results of matched analyses indicated that there was no association between lung cancer mortality and employment in either rubber compounding and mixing jobs or curing jobs. Men who had worked for at least five years in rubber reclaim operations, where there was potentially heavy exposure to particulates and fumes, experienced a twofold increase in lung cancer risk. In addition, there was a 70% excess of lung cancer risk among men employed in making special products, where the primary production activity was fuel cell manufacturing. The latter two findings were marginally statistically significant.

Adult↗
PubMed1986

Peripheral eosinophilia and respiratory symptoms in rubber injection press operators: a case-control study.

To evaluate a suspected association between an outbreak of acute respiratory illness and eosinophilia and employment as a rubber worker, we performed a retrospective review of medical records of rubber workers employed from September 1983 to July 1984 in a plant housing a thermoinjection process. Twenty-five workers met the case definition of a respiratory illness requiring a physician visit. The predominant respiratory illness was acute in onset with cough, chest tightness, and dyspnea. Peripheral eosinophilia, up to 40% of white blood cells in a peripheral smear, was seen in 10 of 18 (56%) cases. Twenty-one of 25 white males with respiratory symptoms were employed in the thermoinjection process (odds ratio = 22, p less than .001). Smoking and employment in this process contributed independently to an increased risk of being a case as determined by a logistic regression analysis. Return to the plant building caused recurrence of symptoms in most cases, and these workers have been transferred or left the company. We conclude that a strong previously unrecognized association exists between employment in this neoprene rubber thermoinjection process and the development of an acute respiratory illness.

Adult↗
PubMed1976

Interference by butyl rubber stoppers in GLC analysis for theophylline.

During a study of the pharmacokinetics of theophylline using GLC analysis, unexpectedly high values occurred in a random manner. The cause of there abnormal values was investigated, and significant interference was observed when blood samples were drawn using evacuated glass tubes sealed with butyl rubber stoppers. In vitro tests using distilled water showed no apparent theophylline levels due to the additives in three commonly used tubes. However, when water was allowed to remain in contact with the butyl rubber stoppers for 1 min, an apparent theophylline content of as high as 5.5 mug/ml was observed. A contact time of 60 min resulted in apparent theophylline levels of as high as 52.3 mug/ml. It was concluded that a substance leached from the butyl rubber stoppers accounted for the spurious results.

Chromatography, Gas↗
PubMed2004

Involvement of Hevea latex organelle membrane proteins in the rubber biosynthesis activity and regulatory function.

Centrifugation of fresh Hevea rubber latex yields three distinct fractions. The sediment bottom fraction (BF) content of membrane-bound organelles is ca. 20 vol.-% of latex. Prolonged storage or delayed use of fresh latex will result in disintegration and loss of the bottom fraction. This is due to the osmotically sensitive BF rupture and its membrane debris being tightly bound to the top rubber particles (RP) phase. The BF membrane was found to be highly active for rubber biosynthesis (RB), in contrast to previous reports that describe RB only occurring on the RP surface. It was clearly shown that washed BF membrane (WBM) was much more active than fresh RP for RB activity. WBM was highly activated by SDS for RB in a biphasic manner, but SDS strongly inhibited the RP. Probably WBM micelle formation resulted in a highly increased active surface area for RB. C55-PP (UPP) was a very active allylic for WBM in RB function, but inactive for RP. Serial acetone extraction of WBM proteins showed a distinct profile of the fractions with different RB activity. WBM isolated proteins suspended in 2% sodium dodecyl sulfate (SDS) with an RB activity equal to that of intact WBM was with the 20% acetone protein fraction. The 60 and 80% fractions were inactive. Combining the 20 with 80% fractions showed a complete inhibition of RB activity. Complete RB loss was also found when WBM was mixed with the 80% fraction, indicating that WBM has both an enzyme system and a factor for regulation of the RB activity in a well controlled metabolic function for the latex RB process.

Acetone↗
PubMed1984

Decreased erythrocyte glutathione s-transferase activity in rubber workers.

Decreased erythrocyte glutathione s-transferase activity was found in workers exposed to hot rubber fumes in two-roll mill and calender departments (6.6 +/- 0.9 and 6.8 +/- 0.8 mumol/min X mg haemoglobin, respectively vs 8.4 +/- 0.5 in controls). This trend was also noted in the general category of all rubber exposed workers without stratification according to their task (7.6 +/- 0.5, n = 30). This result was contrary to that expected, as the cases with the lowest values had the greatest urinary thioether excretion. The thioethers are the end-products of the enzyme-catalyzed glutathione conjugation reaction aimed at the inactivation of potentially toxic chemicals. Thus, it appears that the assay of erythrocyte glutathione s-transferase activity is not very informative about exposure, although the enzyme assay might disclose other, so far unknown, biological effects of reactive rubber chemicals.

Depression, Chemical↗
PubMed1995

Afferent activity in the superior spermatic nerve of lambs--the effects of application of rubber castration rings.

Electrophysiological techniques were used to record afferent activity in the superior spermatic nerves of young lambs under general anaesthesia. Receptive fields were identified in the pampiniform plexus and the deep tissue of the testis in response to mechanical stimulation. Application of a standard rubber castration ring to the scrotal neck evoked vigorous afferent activity, including some from formerly silent units with receptive fields particularly in the pampiniform plexus. Some of this multi-unit discharge adapted rapidly within 10 s of the application of the ring and was followed by a discharge pattern which decayed exponentially over 90 min. The rate of decay of this discharge showed more than one exponent (time constant) with inflections at approximately 90 s and 16 min. After the application of the castration ring, quantitatively controlled scrotal compression continued to excite receptors, though a declining frequency was recorded over the period of observation. It was concluded that: (a) rubber castration rings initiated afferent activity which persisted for periods in excess of 90 min, a time course which is similar to the behavioural and humoral changes in the conscious animal; (b) both standard and small rubber castration rings were ineffective in rapidly producing neuronal pressure block of the slowly conducting afferent fibres in the superior spermatic nerve; (c) intra-testicular injection of local anaesthetic rapidly blocked afferent fibres running in the superior spermatic nerve.

Animals↗
PubMed1984

Hemorrhoids. Measuring the constrictive force of rubber bands.

In ligating hemorrhoids with rubber bands, weaker constrictive force lessens liability to subsequent bleeding but increases that for venous block without complete arterial block. A method applicable in the office is described to assess this force. Thirteen samples of rubber bands tested exhibited very wide differences of this force and also of hysteresis. Some attributes of the desirable rubber band are submitted.

Constriction↗
PubMed1980

Inhibitory effect of rubber on the growth of M. tuberculosis.

Rubber liners used in screw-cap bottles in Hong Kong were found to inhibit the growth of M. tuberculosis in culture media but not to exert any inhibitory effect on the bacilli in sputum. The British Standard for testing rubber used in transfusion equipment (BS: 2463) does not detect the inhibitory effect. It is recommended that rubber liners in the caps of bottles used for growing M. tuberculosis should be tested for cytotoxicity by a modification of the method described in British Standard 5213 or by the simple bacteriological tests described in this report.

Culture Media↗
PubMed1994

IgE immune response to rubber proteins in adult patients with latex allergy.

In the present immunoblot study we examined IgE immune responses to natural rubber latex proteins in sera from 27 adult patients with latex allergy. We demonstrated at least 30 proteins in the rubber tree sap, of which 19 bound IgE antibodies in a heterogeneous manner in patient sera. Twenty-two of the 27 patient sera (81%) showed positive immunoblot test results. IgE antibodies in the patient sera bound most frequently to a 20 kd allergen, which was recognized by 17 of the 22 (77%) patient sera with positive immunoblot test results. These results suggest that a 20 kd rubber protein could be a major allergen in adult patients with latex allergy. Immunoblotting with a representative set of allergens as antigen would offer a sensitive, confirmatory in vitro test to demonstrate hypersensitivity to latex.

Adult↗
PubMed1988

Use of a modified natural-rubber phantom for radiotherapy dosimetry measurements.

The utility of a phantom material, based on SMR(L) [Standard Malaysian Rubber] grade natural rubber and a formulation used for the proprietary rubber phantom-material, Temex, has been examined for the 1-MeV photon-Measurement has also been performed with 60-keV photons using the radionuclide 241Am. At photon-therapy energy levels the measured response, when compared with tabulated central-axis percentage depth doses for the defined measuring conditions, produces everywhere (in the range 1-19 cm depth) better than 2% deviation. The favourable measured response characteristics combined with the ease of processing and casting the phantom material provide the basis for useful radiotherapy machine calibration and anthropomorphic dosimetry measurements. The measured mass-attenuation coefficient, at 60keV, of 0.204 cm2 g-1 (+/- 3%) is in close agreement with tabulated values for water (0.2055 cm2 g-1).

Cobalt Radioisotopes↗
PubMed2006

Experience with elastic rubber bands for the tie-over dressing in skin graft.

We derived a dressing using elastic rubber bands to tie over the skin graft. This is a simple, easy to perform, timesaving, inexpensive and reliable method for applying pressure over the skin graft compared with traditional methods. Between September 2002 and August 2004, we have used the present dressing technique in 35 patients with 36 grafts in various parts of the body. We chose this method, because of some anatomic areas, such as back, and buttock, which are frequently quite difficult to maintain pressure dressings in place, minimal movement can cause the skin graft to dislodge. The elastic rubber bands, rather than threads, are used as tie-over. Such a dressing permits expansion and contraction, providing a dynamic quality in the most difficult anatomic locations. The patient group consisted of 23 males and 12 females. The age ranged from 34 to 82 years (mean 52.4 years). Defect size ranged from 3x2.5 to 30x20 cm2 (mean 11.2x7.0 cm2 in size). The average follow-up was 5.8 months (range: 1-12 months). Among the 36 grafts in our study, all grafts except four showed good to excellent results. The mean graft successful rate is 88%. With our procedure no hematoma formation or shearing force (except one case) occurred in this group of patients during the phase of revascularization, there was, hence, good fixation of the graft by the "tie-over" dressing using elastic rubber bands compared with conventional tie-over dressing, especially in skin grafts of the back site of body and at large graft area. However, it is not suitable for the potentially infectious granulation beds, especially near joint area.

Adult↗
PubMed2004

Analysis of low-molar-mass materials in commercial rubber samples by Soxhlet and headspace extractions followed by GC-MS analysis.

Very tight regulations apply to materials used for pharmaceutical packaging and for administering drugs. In this paper, we describe a simple and reliable procedure involving both gas- and liquid-phase extraction steps followed by an analysis step to identify the low-molar-mass materials in commercial-rubber samples. Representative commercial rubbers, that could be used for pharmaceutical packaging, have been selected and cryogenically powdered. Headspace and Soxhlet extractions have been carried out and the key parameters are discussed. The obtained extracts have been analyzed by gas chromatography (GC)-mass spectrometry (MS). More than 100 compounds have been detected and identified. Headspace allowed to extract the more-volatile compounds, whereas Soxhlet extraction recovered less-volatile compounds, but induced a loss of the volatile ones. Thus, both extraction techniques are required to fully characterize the low-molar-mass compounds present in rubber.

Gas Chromatography-Mass Spectrometry↗
PubMed2000

The rubber dam interposition technique during intracranial aneurysm clipping under deep hypothermic circulatory arrest.

OBJECTIVE: We describe a technique for isolating perforating arteries by use of a rubber sheet during the clipping of intracranial aneurysms under deep hypothermic circulatory arrest. METHODS: After meticulous dissection of the perforating arteries from the aneurysm, a rubber sheet, cut from a surgical glove to the proper shape, is inserted between the aneurysm and the arteries to prevent arterial reattachment to the aneurysmal neck. RESULTS: Even when perforators are invisible at the time of neck clipping because of a large aneurysmal body, the blade of the clip slides along the rubber sheet without injuring the vessels. CONCLUSION: With this method, an aneurysm, especially a large or giant one, can be clipped easily and safely even when the patient is in deep hypothermic circulatory arrest.

Female↗