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PubMed1991

Statherin: a major boundary lubricant of human saliva.

The lubricating properties of human submandibular-sublingual salivary fractions were examined using a servohydraulic model of mandibular movement. Fractions containing statherin exhibited a strong tendency to boundary lubrication. The lubricity of purified statherin was confirmed and compared to the amphipathic molecules gramacidin S and sodium dodecyl sulfate. Contact angle measurements of statherin paralleled the other amphipathic molecules. The helical content of statherin increased in trifluoroethanol indicating the presence of amphipathic helical regions. CD studies and hydrophobic moment calculations indicated that statherin adopts an amphipathic helical conformation at the N-terminus. An energy-minimized model of the polar N-terminal residues 1-15 suggested that this domain could be positioned in space to interact with a hydroxyapatite substrate. These data imply that under appropriate conditions statherin may display an amphipathic nature which enables it to function as a boundary lubricant on enamel.

Adult↗

PubMed2002

Lubrication of the vaginal introitus and speculum does not affect Papanicolaou smears.

OBJECTIVE: To test the hypothesis that lubrication of the vaginal introitus and external speculum does not adversely affect Papanicolaou interpretation. METHOD: One hundred eighty-two patients presenting for Papanicolaou smears as part of their visit were randomly assigned to have either only warm water or a water soluble lubricant to assist speculum insertion. Cytotechnicians and pathologists were blind to the cohort from which smears were obtained. RESULTS: Two unsatisfactory smears were found among 93 patients with the lubricant and two were found among 89 using only warm water. No significant difference was found using the t test for continuous variables and chi(2) for categoric variables. CONCLUSION: Use of a water soluble lubricant on the vaginal introitus and external speculum facilitates examination with no adverse effect on Papanicolaou smear interpretation.

Adult↗

PubMed2001

Lubricants based on renewable resources--an environmentally compatible alternative to mineral oil products.

The development of lubricants like, e.g. engine and hydraulic oils was traditionally based on mineral oil as a base fluid. This fact is related to the good technical properties and the reasonable price of mineral oils. The Report to the Club of Rome (W.W. Behrens III, D.H. Meadows, D.I. Meadows, J. Randers, The limits of growth, A Report to the Club of Rome, 1972) and the two oil crises of 1979 and 1983, however, elucidated that mineral oil is on principle a limited resource. In addition, environmental problems associated with the production and use of chemicals and the limited capacity of nature to tolerate pollution became obvious (G.H. Brundtland, et al., in: Hauff, Volker (Ed.), World Commission on Environment and Development (WCED), Report of the Brundtland-Commission, Oxford, UK, 1987), and the critical discussion included besides acid rain, smog, heavy metals, and pesticides also mineral oil (especially oil spills like the case Exxon Valdes). A disadvantage of mineral oil is its poor biodegradability and thus its potential for long-term pollution of the environment. From the early development of lubricants for special applications (e.g. turbojet engine oils) it was known, that fatty acid polyol esters have comparable or even better technical properties than mineral oil. Subsequently, innumerable synthetic esters have been synthesized by systematic variation of the fatty acid and the alcohol components. Whereas the alcohol moiety of the synthetic esters are usually of petrochemical origin, the fatty acids are almost exclusively based on renewable resources. The physico-chemical properties of oleochemical esters can cover the complete spectrum of technical requirements for the development of high-performance industrial oils and lubricants (e.g. excellent lubricating properties, good heat stability, high viscosity index, low volatility and superior shear stability). For a comprehensive review of their technical properties see F. Bongardt, in: Jahrbuchfür Praktiker, H. Ziolkowsky (Ed.), Verlag für chemische Industrie GmbH, 1996, pp. 348-361. This article will focus on the ecological properties of oleochemical (synthetic) esters. The environmental relevance of oleochemicals in comparison to petrochemicals is discussed, and then the principles of an ecological assessment are described. The ecotoxicological properties and the biodegradability of oleochemical esters are presented. Finally, the ecological properties of the oleochemical esters are discussed with regard to existing environmental classification and labeling systems.

Alkenes↗

PubMed2001

Environmental assessment of lubricants before and after wire drawing process.

Iron wire drawing processes involve the use of solid lubricants made of powdered raw materials, which lead to industrial wastes after being used. These wastes, based on stearates, have a negative effect on the environment. This study deals with the environmental assessment of some lubricants before and after the wire drawing process in a Spanish factory. The parameters evaluated for this study have been total organic carbon (TOC), mobility of zinc and lead, and ecotoxicity (EC(50)). Results show that wastes have more ecotoxicity than the original lubricants due to the content of metals that lubricants pick up from the wire, as pickling, patenting and galvanising take part in the manufacture. The capture of metallic particles leads to a reduction of TOC and an increase in ecotoxicity.

Biological Assay↗

PubMed2005

Porcine gastric mucin (PGM) at the water/poly(dimethylsiloxane) (PDMS) interface: influence of pH and ionic strength on its conformation, adsorption, and aqueous lubrication properties.

We have investigated the influence of pH and ionic strength on the conformation of porcine gastric mucin (PGM) in bulk aqueous solution, its adsorption behavior onto poly(dimethylsiloxane) (PDMS) surfaces, and its lubricating behavior upon the self-mated sliding contact of a PDMS tribopair by means of circular dichroism (CD) spectroscopy, optical waveguide lightmode spectroscopy (OWLS), and pin-on-disk tribometry, respectively. In a low-concentration regime (1 mg/mL), where the formation of a mucus-gel is generally excluded, PGM is still observed to exhibit effective aqueous lubricating properties under specific conditions of acidic pH and low ionic strength. This behavior was closely correlated with specific conformations in the bulk solution as well as specific adsorption behavior at the water/PDMS interface. The lubrication mechanism of the self-mated sliding contact of PDMS by means of surface modification with PGM is discussed in terms of isoviscous-elastic/soft-elastohydrodynamic lubrication (soft-EHL).

Adsorption↗

PubMed2002

The characterization of oil-degrading microorganisms from lubricating oil contaminated (scale) soil.

AIMS: To isolate and characterize oil-degrading microorganisms from contaminated (scale) soil. METHODS AND RESULTS: Oil-degrading microorganisms were isolated from enrichment cultures of scale soil. Each isolate was identified using 16S rDNA gene and oil degradability was determined on both unused and used lubricating oil. The weight of the extracted remaining oil revealed that most isolates degraded unused lubricating oil more than used lubricating oil. Chemical composition of oil analysed by TLC-FID and GC-MS demonstrated that Nocardia simplex W9 degraded used oil the best, and resulted in a decrease in saturates, aromatics and resins to 52.46, 38.13 and 18.81%, respectively. CONCLUSIONS: Nocardia simplex W9 is the best degrader, among all the isolates, on both used and unused lubricating oil. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of Nocardia simplex W9 in scale soil enables iron to be recycled by biodegradation.

Biodegradation, Environmental↗

PubMed2005

Oil-lubricated colonoscopy: easier and less painful?

BACKGROUND AND STUDY AIMS: Methods of lubrication are rarely considered to be a matter for study in gastrointestinal endoscopy. We evaluated a new technique, i. e. the release of seed oil in discrete amounts from the tip of the scope during colonoscopy. PATIENTS AND METHODS: 346 consecutive patients prospectively underwent colonoscopy with a standard lubricating method (using water-soluble jelly; group A) or with the standard method plus seed oil (corn oil) instillations through the biopsy channel (group B). The following variables were evaluated in the two groups: the success rate for total intubation, and the time required to reach the cecum; the time needed to examine the colon at withdrawal; the detection rates for colorectal diseases; the level of pain and degree of difficulty associated with the examination. Patients in whom total colonoscopy was not achieved were asked to undergo a further examination in which the other lubricating technique was used. RESULTS: Successful intubation to the cecum was significantly more frequent ( P < 0.005) in the oil lubrication group (group B, 159/168) than in the control group (group A, 145/170), and less time was needed ( P < 0.001). No significant differences were found with regard to time for examination at withdrawal and detection rates for colorectal diseases. Level of pain and degree of difficulty during colonoscopy were significantly lower in the oil group ( P < 0.001). In the cross-over examinations done in patients in whom total colonoscopy was not achieved, no statistical difference was found between the two groups. We observed no side effects for patients or damage to the instrument. CONCLUSIONS: The proposed technique could be a simple, safe, and inexpensive method for easier and less painful colonoscopy; moreover, it might facilitate difficult examinations. Further studies are needed to confirm our data and to ensure that the use of this technique is not liable to damage the scope.

Adult↗

PubMed2003

Generic scenario for the impact of cooling lubricants into the hydrosphere.

According to directive 93/67/EEC of the European Commission, this paper deals with the generic exposition evaluation of the environmental concentration of cooling Lubricant chemicals from the metal working industry into the hydrosphere. After considering the relevant life-cycle steps and the selection of a representative point source for the 'reasonable worst case', the emission per day Elocal(water) is determined. It leads to the predicted environmental concentration (PEClocal(water)) for the local stage in the compartment water. In order to gain the PEClocal(water) for an example--a corrosion inhibitor as additive in a cooling lubricant--, the relevant emission paths and the corresponding representative point source are described for the reasonable worst case. For non-water-miscible cooling lubricants, none of the operations in the life cycle leads to a release into the compartment water. To evaluate the hazard potential for cooling lubricant chemicals, the complete risk assessment has to be done. Also, the assessment has to be done for all high production volume chemicals, new substances and existing hazard chemicals. This means that even industrial categories like chemicals used in the textile industry or biocides and others have to be evaluated.

Biological Availability↗

PubMed2006

Numerical analysis of the effects of material parameters on the lubrication mechanism for knee prosthesis.

The tibial component of current knee prostheses made of ultra high molecular weight polyethylene (UHMWPE) has a high degree of wear that causes knee inflammation, prosthesis loosening and subsequent replacement in not more than 15 years. In order to know which UHMWPE material properties have more influence on wear, a steady state lubrication model with non-Newtonian synovial fluid has been studied through numerical solution. The results show that UHMWPE has a very high elastic modulus that makes difficult a well lubricated artificial joint and induces the formation of very thin lubricating films between the moving surfaces with the same magnitude of roughness components. This study shows that the use of deformable porous materials in the tibial component could cause the lubricating film thickness to be higher than the average roughness and the pressure levels to be lower than the one predicted for UHMWPE. These two facts imply friction and wear reduction.

Biocompatible Materials↗

PubMed2004

Impact of engine lubricant properties on regulated gaseous emissions of 2000-2001 model-year gasoline vehicles.

The impact of the sulfur (S) content in lubricating oil was evaluated for four ultra-low-emission vehicles and two super-ultra-low-emission vehicles, all with low mileage. The S content in the lube oils ranged from 0.01 to 0.76%, while the S content of the gasoline was fixed at 0.2 ppmw. Vehicles were configured with aged catalysts and tested over the Federal Test Procedure, at idle and at 50-mph cruise conditions. In all testing modes, variations in the S level of the lubricant did not significantly affect the regulated gas-phase tailpipe emissions. In addition to the regulated gas-phase emissions, a key element of the research was measuring the engine-out sulfur dioxide (SO2) in near-real-time. This research used a new methodology based on a differential optical absorption spectrometer (DOAS) to measure SO2 from the lubricants used in this study. With the DOAS, the contribution of SO2 emissions for the highest-S lubricant was found to range from less than 1 to 6 ppm on a gasoline S equivalent basis over the range of vehicles and test cycles used. The development and operation of the DOAS is discussed in this paper.

Air Pollutants↗

PubMed1993

Evaluation of shipboard formation of a neurotoxicant (trimethylolpropane phosphate) from thermal decomposition of synthetic aircraft engine lubricant.

MIL-L-23699 lubricants that are composed principally of trimethylolpropane triheptanoate (TMP) and tricresyl phosphate (TCP) have been shown to form a neurotoxicant, trimethylolpropane phosphate (TMPP), during pyrolysis and/or combustion. Mechanistically, TMPP is thought to irreversibly inhibit the GABA-mediated inhibitory response and thereby produce epileptiform clonic/tonic seizures with convulsions followed by death. Thermal decomposition of MIL-L-23699 lubricant produces TMPP under laboratory conditions, but this product has not been detected in the workplace following actual fires. This study has examined whether TMPP is produced during an actual shipboard fire by placing the synthetic lubricant in a fire environment aboard the ex-U.S.S. Shadwell, Mobile, Alabama. Both biological and chemical analyses were performed on the thermally decomposed lubricant to ensure detection of the neurotoxic material. Under the conditions of this study, the formation of TMPP during a shipboard fire was confirmed. The implications of this finding for safe management of post-fire cleanup are discussed.

Bridged Bicyclo Compounds, Heterocyclic↗

PubMed2003

Talc functionality as lubricant: texture, mean diameter, and specific surface area influence.

Talc is widely used as a glidant (flow regulator) for powders. This study highlights the characteristics that confer to talcs new end use properties in improving the lubrication function during compression. We studied the contribution of texture, mean diameter (D50), and specific surface area on the residual die pressure, the ejection pressure, the lubrication index, and the tablet hardness. Different textures were studied: microcrystalline, macrocrystalline, and moderately macrocrystalline talc grade. The compression parameters were improved according to the texture. D50 varies from 0.62 to 15 microm. As D50 decreases, the lubrication performance is improved. Finally, the specific surface area of talcs was studied. This last characteristic of talcs was shown as the most relevant parameter in determining lubrication ability.

Excipients↗

PubMed2005

Randomized double-blind comparison of lidocaine gel and plain lubricating gel in relieving pain during flexible cystoscopy.

PURPOSE: To compare the pain induced by outpatient flexible cystoscopy in men having local lidocaine jelly application or plain lubricant. PATIENTS AND METHODS: We performed a randomized, double-blind study to compare the anesthetic effect of intraurethral 2% lidocaine gel (N = 45) and plain lubricant (N = 46) in men undergoing outpatient flexible cystoscopy. The age, prostate size, and examination time were similar in the two groups. Before cystoscopy, we filled the urethra with 20 mL of gel, which was held for 15 minutes. A 15.5F flexible cystoscope was then used for examination. A 10-point visual analog pain scale (1 = least to 10 = most painful) and a four-point pain grade (grade 1 = least to grade 4 = most painful) were used to measure the pain perception. The amount of postoperative analgesic used and willingness to adopt the same anesthesia for future cystoscopy were also recorded. RESULTS: The mean pain scores for the lidocaine and plain gel groups were 2.8 +/- 1.1 and 2.5 +/- 1.1, respectively (P = 0.06), while the pain grades for the lidocaine gel and plain gel groups were 1.6 +/- 0.6 and 1.8 +/- 0.7, respectively (P = 0.19). In both groups, many patients (42.2% in the lidocaine gel group and 37% in the plain lubricant group) felt the external sphincter and prostatic urethra were the most uncomfortable areas during cystoscopy. Postcystoscopic analgesics were requested by 12 of 45 patients in the lidocaine group, but only 6 of 46 of the plain-gel group (P = 0.103). When patients were asked if they would desire general anesthesia for better pain control in future examinations, five of the lidocaine group responded positively, while three of the plain-gel group said they would (P = 0.62). The cost of lidocaine gel is about thrice that of the plain gel. CONCLUSION: Using plain lubricant is cheaper and faster than applying lidocaine gel. The pain score, pain grade, postcystoscopic analgesic requirement, and anesthetics requested for the next cystoscopy were similar in the two groups. However, a larger investigation will be needed to achieve more significant statistical power.

Aged↗

PubMed1998

Surface-active phospholipid as the lubricating component of lubricin.

To resolve the apparent conflict between a lubricating glycoprotein, 'lubricin', as the active ingredient in synovial fluid (SF) and surface-active phospholipid (SAPL) present in SF (and adsorbed to articular cartilage) as the boundary lubricant reducing friction to such low physiological levels, lubricin was isolated from bovine SF following the original procedure of Swann et al. (Arthritis Rheum 1981;24:22-30). Analysis of the lipid extract by thin-layer chromatography and phosphorus determination demonstrated a phospholipid component of 11.1 +/- 1.7% (N = 5) which corresponds very closely to the 9.2-13.0% of lubricin which had hitherto remained unidentified and which has previously been shown to be transferable to the articular surface to impart lubrication. These results would appear to resolve any theoretical conflict in that lubricin is, indeed, an active ingredient within SF. Yet, as a large water-soluble molecule, it really functions as a carrier for the highly insoluble SAPL which it deposits on the articular surface as the oligolamellar layer visualized in previous studies. However, it is this deposited SAPL, rather than lubricin, which actually lubricates.

Animals↗

PubMed2003

Effectiveness of lidocaine lubricant for discomfort during pediatric urethral catheterization.

PURPOSE: Many children with urinary tract infections and vesicoureteral reflux require catheterization. Catheterization can be a painful experience, and a desire to avoid this experience may affect patient care. We evaluated the effectiveness of lubricant containing lidocaine for minimizing patient pain and distress during catheterization. MATERIALS AND METHODS: We conducted a prospective, double-blind, placebo controlled trial. Twenty children (16 girls and 4 boys, mean age 7.7 years) had urethral lubricant with or without lidocaine placed within 10 minutes before urethral catheterization. In all children pre-procedure anxiety, and pain and distress during catheterization were recorded. Pre-procedure anxiety was measured using a visual analog scale, pain was measured with the Oucher Pain Scale and distress was recorded by 2 independent observers with a simple 7-point Likert-type scale. RESULTS: There were no significant group differences for age, number of previous catheterizations or pre-procedure anxiety. The group receiving lubricant with lidocaine had significantly lower pain (21 +/- 19.69 versus 65.5 +/- 26.29) and distress (2.65 +/- 1.97 versus 4.7 +/- 2.07) (p = 0.001 and 0.007, respectively). CONCLUSIONS: The use of lubricant with lidocaine significantly decreases pain with pediatric urethral catheterization and is recommended with pediatric catheterizations.

Anesthetics, Local↗

PubMed2006

The effect of gel lubrication on cuff leakage of double lumen tubes during thoracic surgery.

High-volume, low-pressure tracheal cuffs of disposable double lumen tubes may offer limited protection to the dependent lung if fluid leaks through folds in the inflated cuffs. This study was undertaken to determine the incidence of fluid leakage past the tracheal cuff and whether gel lubrication reduces the incidence. Fifty-five patients were randomly assigned to receive a double lumen tube with or without gel lubrication. The dependent lung was intubated. With the patient in the lateral position, methylthionium chloride was administered above the tracheal cuff via a pre-attached catheter. Fibreoptic bronchoscopy was performed to determine if dye had passed the tracheal cuff. Three patients were excluded. Dye leakage was seen in 12/27 and 3/25 patients in the unlubricated and lubricated group, respectively (p = 0.014). Gel lubrication significantly reduces fluid leakage past the tracheal cuff of a double lumen tube and should be considered for all thoracic surgical patients requiring one-lung ventilation.

Adult↗

PubMed1995

Remarkable lubricating capabilities of amniotic surfactant.

Surface-active phospholipid (SAPL) extracted from amniotic fluid or elutriated from the chorioamnionic sacs of placentas recovered from normal full term deliveries has been shown to be a remarkable lubricant. Coefficients of kinetic and static friction were reduced to 0.009 by SAPL from amniotic fluid and 0.011 for a membrane extract, even under high load (3 kg/cm2), compared with 0.04 for the best nonbiological boundary lubricants. The antiwear properties were equally remarkable, giving a mean scar diameter under extreme pressure of only 0.76 mm for amniotic SAPL and 1.00 mm for membrane extract compared with 0.85-0.95 mm for aqueous lubricants commercially available. These results support the hypothesis that premature rupture (PROM) is less likely to occur if movement between the fetus and the amnion or between the decidual surface of the uterus and the chorion is well lubricated.

Amniotic Fluid↗

PubMed1999

Comparison of topical anesthetics and vasoconstrictors vs lubricants prior to nasogastric intubation: a randomized, controlled trial.

OBJECTIVE: To determine whether pre-treatment of the nose and throat with topical anesthetics and vasoconstrictors would reduce the pain associated with nasogastric (NG) intubation. METHODS: This was a prospective, randomized, controlled trial assessing the pain of NG intubation in patients pretreated with topical anesthetics and vasoconstrictors vs surgical lubricants alone. The subjects were 40 alert, cooperative adult patients requiring NG intubation without allergies to the study medications or contraindications to their use from a suburban university-based ED. The patients in the experimental group had phenylephrine 0.5% sprayed in their noses followed by instillation of 5 mL of 2% lidocaine jelly. Their throats were sprayed with 2% tetracaine and 14% benzocaine. The control patients received intranasal lubrication only. The primary outcome measured was pain of NG intubation on a 100-mm visual analog scale. Other outcomes included nasal pain, discomfort from gagging, and the incidences of vomiting, choking, and epistaxis. RESULTS: The mean age (+/-SD) was 54.8+/-22.3 years; 20 (50%) were female. The patients who had a combination of topical anesthetics and vasoconstrictors inserted prior to NG intubation experienced significantly less overall pain/ discomfort than did the control patients [28.6 mm (95% CI = 17.3 to 39.9 mm) vs 57.5 mm (95% CI = 44.9 to 70.1 mm), p = 0.001]. The patients in the experimental group also experienced significantly less nasal pain than did the patients in the control group [18.1 mm (95% CI = 8.0 to 28.2 mm) vs 44.4 mm (95% CI = 30.4 to 58.6 mm), p = 0.003] and significantly less discomfort from gagging than the patients receiving pretreatment with a lubricant alone [24.1 mm (95% CI = 11.1 to 37.1 mm) vs 50.9 mm (95% CI = 36.7 to 65.1 mm), p = 0.006]. There was no between-group difference in the frequencies of adverse effects. CONCLUSIONS: Use of topical lidocaine and phenylephrine for the nose and tetracaine with benzocaine spray for the throat prior to NG intubation results in significantly less pain and discomfort than use of a nasal surgical lubricant alone. Widespread use of topical anesthetics and vasoconstrictors prior to NG intubation is recommended.

Administration, Topical↗