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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.
Since a rise of 1.0 C in temperature causes a 10% increase in tissue metabolism, a wheelchair cushion which limits changes in skin temperature, and thus metabolic demand, might effectively reduce ischemic tissue damage. Skin temperature changes were measured under the ischial tuberosities and thighs of normal subjects while sitting on several types of support surfaces. The effect of commercially available wheelchair cushions on sitting surface skin temperatures was measured in five normal men and five normal women, age 20 to 30 years. The sitting surfaces studies were latex rubber cushions with nylon-vinyl and cotton polyester covers, two types of gel cushions, and a water flotation pad. Skin surface temperatures were recorded under both ischial tuberosities and both posterior thighs during each 30-minute test period. Increases in skin temperature averaging 2.3 C to 2.5 C under the ischial tuberosities and 3.2 C to 3.5 C under the thighs were noted when the subjects sat on either of the latex rubber cushions. A temperature drop of 3.1 C was noted under the ischial tuberosities and 2.2 C under the thighs when using the water flotation pad. The skin temperature remained relatively static while sitting on the gel cushions.
The reaction of the urethra to two new polyurethrane polymers was compared with those produced by materials currently used in the manufacture of urethral catheters. The comparison included silicone, latex rubber, tetrafluoroethylene polymer (Teflon) coated latex, and polyvinyl chloride. There were no significant differences in the reaction of the urethra to the various materials. The present study was carried out in the absence of bacterial contamination.
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.
T-drainage tubings consisting of siliconized latex, silicone rubber, siliconized latex with additional silicone treatment of the surface of the short legs, or silicone rubber with PVC covering of the long branch were tested in experiments with dogs. Fibrous encapsulation, incrustation, and behaviour of the material were checked after 1, 2, 4, and 12 weeks. Siliconized latex proved to be the most suitable material.
A small portable chamber for the recovery of anaerobic bacteria is described. This rigid chamber is constructed of clear acrylic with dimensions of 30 inches (ca. 76.2 cm) wide, 18 inches (ca. 44.7 cm) deep, and 18 inches (ca. 44.7 cm) high. Conventional bacteriological techniques can be used inside the chamber to efficiently isolate strict anaerobic organisms. An adapter allows the attachment of a standard anaerobic jar to the outside of the chamber. The jar can be used to store reduced media. Once the jar is attached to the chamber and the media is removed to the interior of the chamber, the jar is available to receive inoculated media. The anaerobic jar can then be removed from the chamber, without contaminating the jar or chamber with oxygen, and be placed in a conventional 37degreesC incubator. This chamber also allows the microbiologist to process cultures without wearing gloves as was necessary with previous anaerobic chambers. Air-tight latex rubber sleeves seal around the microbiologists arms and to the armport flange of the chamber to prevent the introduction of oxygen into the chamber. Anaerobic conditions are maintained by circulating a 80% N2, 10% H2, 10% CO2 gas mixture through alumina pellets coated with palladium. This study indicates that anaerobic conditions obtained in this chamber are sufficient for recovery of obligate anaerobes.
In this study, the pressure/strain and stress/strain relatioships of 44 jugular and 31 femoral canine vein segments were compared with 17 carotid artery specimens, latex rubber, and a synthetic graft material, expanded polytetrafluoroethylene. A method is described for comparing the elastic properties of vein wall specimens of varying thicknesses such as occur after implantation into the arterial circulation. A flat sheet of opened vessel wall, fexed between retention rings at one end of a saline-filled steel cylinder, was biaxially distended to form a bubble shape. Compliance ratio and stress modulus were computed at 20-mmHg increments from 20 to 200 mmHg. In the "arterial" pressure range, vein was less compliant than artery. Vein also had a higher stress modulus E (dyn/cm2 X 10(6)) +/- SE at a chamber pressure 120 mmHg than artery (E = 11 +/- 0.6), and jugular vein was stiffer (E = 65 +/- 3.6) than femoral vein (E = 41.5 +/- 2.0). Changes in the structural properties of vein grafts measured using this technique are potentially important factors leading to graft failure.
The commercial production of styrene was started in the 1930s. Currently 7 million tons of styrene a year is made worldwide by the catalytic dehydrogenation of ethylbenzene or by a process in which styrene is produced as a coproduct with propylene oxide. An estimated 62% of the styrene monomer is consumed in the manufacture of polystyrene, 12% in acrylonitrile-butadiene-styrene resins, 17% in styrene-butadiene rubber and latex, 7% in unsaturated polyester resins, and 2% in other applications. Occupational exposure to styrene occurs in monomer production and polymerization plants, during the fabrication of plastic products from monomeric or partly prepolymerized styrene, and during the transportation and handling of liquid styrene. Due to unreacted residual monomer or thermal degradation of the polymer, low concentrations of styrene can be detected during the use of plastic products. The most extensive and intensive exposure occurs in the reinforced plastics industry, in which over 200,000 workers are exposed to a styrene concentration typically ranging from 20 to 300 ppm.
The criteria used presently for evaluating the materials for haemotherapy, which are based on chemical, physicochemical and biological extracts of aqueous solutions have been found to differ from the results observed after actual prolonged contact of these materials with blood and its elements. All the investigated plastic materials complied with the required quality standards, and, despite this, some of them, such as natural latex or siliconized rubber, caused considerable adhesion of proteins, release of high amounts of haemoglobin from the erythrocytes, and have been found even most thrombogenic of all 8 plastic materials tested. Investigations by means of scanning microscopy demonstrated that adhesion of fibrinogen and thrombocytes to the surface of the plastic materials depended to a high extent on the smoothness of this surface. It depended also on migration of components specific for each material. This was also the cause of variations in the adsorption of albumin, globulin, and fibrinogen labelled with 125I after their mixing with plasma.
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.
The authors propose a conservation method developed at the Department of Normal Anatomy of the Pavlov First Medical Institute. The conservation is performed by simultaneous using of chemicals upon which the method is based: conservant and latex. The conservant is a mixture of glycerine, potassium acetate and water in proportion 45% : 10% : 45%. The latex is industrial artifical rubber.
A case of contact wealing to rubber gloves attributed to natural latex from Hevea braziliensis is described.
During cuffed intubation, damage to the trachea is least likely when the lateral wall pressure exerted by the cuff does not exceed the mean capillary perfusion pressure of the mucosa. A study was carried out of eight different types of endotracheal tubes. At the seal point the traditional red rubber tube and the armoured latex and Softway tubes exerted pressures above the mean systemic arterial pressure. Although the Portex and Mallinckrodt tubes exerted pressures close to the mean capillary perfusion pressure, much higher pressures resulted if they were overinflated. The Lanz tube, however, with its over-pressure safety balloon, maintained a lateral wall pressure below the mean capillary perfusion pressure even when inflated considerably beyond the seal point. Endotracheal cuffs are often overinflated in clinical practice. Since cuff-induced tracheal damage is most influenced by the lateral wall pressure, these results suggest that the use of Lanz-type tubes should be mandatory in intensive care units or when a cuffed tracheostomy tube is required and they should also be considered for use in more routine anaesthetic practice.
A conduit occlusor is presented consisting of a tube surrounded by foam rubber and covered by a latex membrane, with a polyurethane cap attached to the other end. A valve imbedded in the cap allows voluntary urine drainage. This atraumatic, pneumatic, non-invasive occlusor device was used quite succesfully in 3 volunteers who had had a colon conduit urinary diversion. The device was well-tolerated, leakage was effectively prevented. Further experience, however, will be necessary for final evaluation.
Investigating possible application of the DCT-30 thermoelastoplastic shows advantages of some physico-technical properties of this product based on natural caoutchouc and latex by comparison with base-rubber onene. It justifies recommending the former for making injection tubes in the blood transfusion systems.
A new commercial test of IgG-sensitized latex particle agglutination is compared with a long-established latex test for detection and titration of rheumatoid factors. The comparison was conducted on samples from three groups of patients: 125 with seropositive rheumatoid arthritis (RA), 115 seropositive samples from patients with various diseases except RA, and 100 seronegative samples with varying diagnosis including RA. The new test is very simple to perform. Its sensitivity, however, was lower than that of the Rheins test by about 2.5 dilutions. Its specificity as to the diagnosis of RA was significantly better than that of the Rheins test.
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