SEARCH · PubMed Health

Results for “LUBRICATION”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources

PubMed1982

Effect of various analgesics and lubricants on isolation of Chlamydia trachomatis and Neisseria gonorrhoeae.

Five preparations used as analgesics or lubricants in surgical, obstetrical, gynecological, and investigative procedures were tested for their effect on the isolation of Chlamydia trachomatis. Three lignocaine preparations and a lubricating jelly containing 2% phenol were inhibitory to chlamydiae. In contrast, K-Y lubricating jelly was relatively nontoxic to chlamydiae. Since K-Y jelly also had only slight toxic activity against gonococci, it is recommended for the lubrication of instruments which need to be used for the efficient isolation of these microorganisms.

Analgesics↗

PubMed1984

Surfactants identified in synovial fluid and their ability to act as boundary lubricants.

Thin-layer chromatography has been used to identify phospholipids extracted from canine synovial fluid, the major component (45%) being phosphatidyl choline (PC). The extracts and their components have been shown to be surface active in reducing the surface tension of water and to be readily adsorbed to hydrophilic solids, whose surfaces then become hydrophobic. These adsorbed monolayers of synovial surfactant were then found to be excellent boundary lubricants in vitro, reducing the coefficient of kinetic friction (mu) in the dry state and under physiological loading by up to 97% for extracts and 99% for PC alone, reaching mu = 0.01. Surface-active phospholipid is put forward as the possible active ingredient in joint lubrication and shown to be consistent with previous biochemical studies to elucidate its identity. The model essentially follows the classical Hardy model for boundary lubrication imparted by surfactants. It is discussed in relation to a new approach in providing artificial lubrication and facilitating tissue release in patients with arthritis.

Animals↗

PubMed1992

Effects of pharyngeal lubrication on the opening of obstructed upper airway.

We examined the effect of electrical stimulation of the hypoglossal nerve and pharyngeal lubrication with artificial surfactant (Surfactant T-A) on the opening of obstructed upper airway in nine anesthetized supine dogs. The upper airway was isolated from the lower airway by transecting the cervical trachea. Upper airway obstruction was induced by applying constant negative pressures (5, 10, 20, and 30 cmH2O) on the rostral cut end of the trachea. Peripheral cut ends of the hypoglossal nerves were electrically stimulated by square-wave pulses at various frequencies from 10 to 30 Hz (0.2-ms duration, 5-7 V), and the critical stimulating frequency necessary for opening the obstructed upper airway was measured at each driving pressure before and after pharyngeal lubrication with artificial surfactant. The critical stimulation frequency for upper airway opening significantly increased as upper airway pressure became more negative and significantly decreased with lubrication of the upper airway. These findings suggest that greater muscle tone of the genioglossus is needed to open the occluded upper airway with larger negative intraluminal pressure and that lubrication of the pharyngeal mucosa with artificial surfactant facilitates reopening of the upper airway.

Airway Obstruction↗

PubMed1997

Electrical impedance of the cochlear implant lubricants hyaluronic acid, oxycellulose, and glycerin.

Hyaluronic acid (Healon), oxycellulose (hydroxypropyl methylcellulose), and glycerin are lubricants used in cochlear implant surgery for atraumatic deep insertion of the electrode array into the scala tympani. The electrical impedances of these three lubricants were measured to assess possible effects on intraoperative evoked response measurements, such as the electrically evoked stapedius reflex and auditory brain stem response. The impedances of hyaluronic acid, oxycellulose, and saline were very similar and independent of frequency (20 Hz to 1 MHz). Glycerin had an excessively high impedance at low frequencies. A film of hyaluronic acid or oxycellulose around the electrode array immersed in saline did not have any measurable effect on the impedance; a film of glycerin resulted in a strongly reactive polarized layer. However, neither the far-field current spread nor the impedance between stimulated electrodes was affected by any of the lubricants applied as a thin film. This suggests that none of these lubricants affect intraoperative responses, when applied as a thin film.

Cochlear Implants↗

PubMed2005

An open-label evaluation of HP-Guar gellable lubricant eye drops for the improvement of dry eye signs and symptoms in a moderate dry eye adult population.

OBJECTIVE: Evaluate the efficacy of a polymer hydroxypropyl guar (HP-Guar) gellable lubricant eye drop (Systane* Lubricant Eye Drops) in reducing dry eye signs and symptoms among dry eye patients who exhibited at least moderate signs and symptoms. METHODS: 168 patients with moderate dry eye signs and symptoms were enrolled at 29 sites in this open label study. The mean age of patients was 62 years with a minimum age of 28 years and a maximum of 90 years. One hundred and forty-seven patients completed the study, 111 female and 35 male, excluding 1 subject (gender not captured). In order to be included in the study, subjects were required to have a total corneal staining score > or = 4 (NEI grid) in at least one eye, with a grade > or = 2 in at least one zone of the same eye. Patients also had to indicate that their eyes 'felt dry enough to want to use eye drops' at least 'some of the time' on a standardized frequency scale. Eligible patients were dispensed a run-in drop (Opti-Free Express Rewetting Drops*) to use QID for 7 days, and then examined. Patients continuing to meet the inclusion criteria were dispensed the test drops (HP-Guar gellable lubricant eye drops) to use QID, and re-examined on Day 28. At each visit, corneal and conjunctival staining were measured, and six ocular discomfort symptoms were rated on a standardized 0-4 severity scale. At Days 0 and 28, patients subjectively rated product acceptability using a Likert scale. RESULTS: No significant changes in corneal or conjunctival staining were observed with the use of the run-in drop. After 28 days of test drop use, there was a statistically significant reduction in corneal staining (p < 0.0001). Ninety-four percent of patients improved from baseline, with mean reduction in total corneal staining of 4.1 units (0-15 total scale) (62%). Conjunctival staining also improved significantly (p < 0.0001) with a mean total reduction of 3.1 (59%). Patients experienced statistically significant symptomatic relief from day 0 to day 28 for all six ocular discomfort severity questions (p < 0.0001). CONCLUSION: Lubricating drops effectively relieved signs and symptoms associated with moderate dry eye, with measurable improvements evident in both objective staining and subjective questionnaire measures after 28 days in this study population.

Adult↗

PubMed2005

Application of powder rheometer to determine powder flow properties and lubrication efficiency of pharmaceutical particulate systems.

The objective of this study was to understand the behavior of particulate systems under different conditions of shear dynamics before and after granulation and to investigate the efficiency of powder lubrication. Three drug powders, metronidazole, colloidal bismuth citrate, and tetracycline hydrochloride, were chosen as model drugs representing noncohesive and cohesive powder systems. Each powder was individually granulated with microcrystalline cellulose and 5%PVP as a binder. One portion from each granulation was lubricated with different levels of magnesium stearate for 5 minutes. The powder characterization was performed on the plain powders, nonlubricated and lubricated granules using powder rheometer equipped with a helical blade rotating and moving under experimentally fixed set of parameters. The profiles of interaction during the force-distance measurements indicate that powder compresses, expands, and shears many times in a test cycle. Test profiles also clearly reveal existence of significant differences between cohesive and noncohesive powders. In all cases lubrication normalized the overall interactive nature of the powder by reducing peaks and valleys as observed from the profiles and reduced the frictional effect. The developed methods are easy to perform and will allow formulation scientists to better understand powder behavior and help in predicting potential impact of processing factors on particulate systems.

Lubrication↗

PubMed2001

The influence of phospholipid concentration in protein-containing lubricants on the wear of ultra-high molecular weight polyethylene in artificial hip joints.

There is considerable interest in the wear of polyethylene and the resulting wear-debris-induced osteolysis in artificial hip joints. Proteins play an important role as boundary lubricants in vivo in the pseudosynovial fluid, and these are reproduced in in vitro tests through the use of bovine serum. Little is known, however, about the effect of phospholipid concentrations within proteinaceous solutions on the wear of ultra-high molecular weight polyethylene (UHMWPE). The effects of protein-containing lubricants with 0.05, 0.5 and 5 per cent (w/v) phosphatidyl choline concentrations on the wear of ultra-high molecular weight polyethylene (UHMWPE) were compared with 25 per cent (v/v) bovine serum which had 0.01 per cent (w/v) lipid; the effects were compared in a hip joint simulator with smooth (n = 4) and scratched (n = 3) femoral heads. The control bovine serum lubricant produced UHWMPE wear of 55 and 115 mm3/10(6) cycles on the smooth and rough heads respectively. The increased phospholipid concentration significantly reduced the wear rate. At the higher concentration (5% w/v phosphatidyl choline) the average wear was reduced to less than 2 mm3/10(6) cycles. Even with the relatively low concentrations of 0.05% w/v phosphatidyl choline the wear was reduced by at least threefold compared with the bovine serum tests for both the smooth and rough femoral heads. There may be considerable differences in the phospholipid concentrations in patients' synovial fluid and this is highly likely to produce considerable variation in wear rates. In vitro, differences in the phospholipid concentration of lubricants may also cause variation in wear rates between different simulator tests.

Hip Prosthesis↗

PubMed2001

Elastohydrodynamic lubrication analysis of ultra-high molecular weight polyethylene hip joint replacements under squeeze-film motion.

Elastohydrodynamic lubrication was analysed under squeeze-film or normal approach motion for artificial hip joint replacements consisting of an ultra-high molecular weight polyethylene (UHMWPE) acetabular cup and a metallic or ceramic femoral head. A simple ball-in-socket configuration was adopted to represent the hip prosthesis for the lubrication analysis. Both the Reynolds equation and the elasticity equations were solved simultaneously for the lubricant film thickness and hydrodynamic pressure distribution as a function of the squeeze-film time was solved using the Newton-Raphson method. The elastic deformation of the UHMWPE cup was calculated by both the finite element method and a simple equation based upon the constrained column model. Good agreement of the predicted film thickness and pressure distribution was found between these two methods. A simple analytical method based upon the Grubin-Ertel-type approximation developed by Higginson in 1978 [1] was also applied to the present squeeze-film lubrication problem. The predicted squeeze-film thickness from this simple method was found to be remarkably close to that from the full numerical solution. The main design parameters were the femoral head radius, the radial clearance between the femoral head and the acetabular cup, and the thickness and elastic modulus for the UHMWPE cup; the effects of these parameters on the squeeze-film thickness generated in current hip prostheses were investigated.

Arthroplasty, Replacement, Hip↗

PubMed1997

Analysis of fluid film lubrication in artificial hip joint replacements with surfaces of high elastic modulus.

Lubrication mechanisms and contact mechanics have been analysed for total hip joint replacements made from hard bearing surfaces such as metal-on-metal and ceramic-on-ceramic. A similar analysis for ultra-high molecular weight polyethylene (UHMWPE) against a hard bearing surface has also been carried out and used as a reference. The most important factor influencing the predicted lubrication film thickness has been found to be the radial clearance between the ball and the socket. Full fluid film lubrication may be achieved in these hard/hard bearings provided that the surface finish of the bearing surface and the radial clearance are chosen correctly and maintained. Furthermore, there is a close relation between the predicted contact half width and the predicted lubrication film thickness. Therefore, it is important to analyse the contact mechanics in artificial hip joint replacements. Practical considerations of manufacturing these bearing surfaces have also been discussed.

Biocompatible Materials↗

PubMed2006

Importance of head diameter, clearance, and cup wall thickness in elastohydrodynamic lubrication analysis of metal-on-metal hip resurfacing prostheses.

The main design features of metal-on-metal (MOM) hip resurfacing prostheses in promoting elastohydrodynamic lubrication were investigated in the present study, including the femoral head diameter, the clearance, and the cup wall thickness. Simplified conceptual models were developed, based on equivalent uniform wall thicknesses for both the cup and the head as well as the support materials representing bone and cement, and subsequently used for elastohydrodynamic lubrication analysis. Both typical first- and second-generation MOM hip resurfacing prostheses with different clearances and cup wall thicknesses were considered with a fixed large bearing diameter of 50 mm, as well as a 28 mm diameter MOM total hip replacement bearing for the purpose of comparison. The importance of the head diameter and the clearance in promoting elastohydrodynamic lubrication was confirmed. Furthermore, it was also predicted that a relatively thin acetabular cup in the more recently introduced second-generation MOM hip resurfacing prostheses would be capable of improving elastohydrodynamic lubrication even further.

Acetabulum↗

PubMed2006

Effect of lubricant composition on the fatigue properties of ultra-high molecular weight polyethylene for total knee replacement.

Ultrahigh molecular weight polyethylene (UHMWPE) fatigue is a critical factor affecting the longevity of total knee replacement (TKR) bearings. With the increased need for laboratory studies to mimic near in vivo conditions for accurate characterization of material performance, the present study investigated the role of hyaluronic acid (HA) in testing lubricant on the crack growth response of UHMWPE. It was hypothesized that the change in lubricant viscosity as a result of HA would affect the fatigue life of the polymer. A fracture mechanics approach as per ASTM E 647 was adopted for this study. Surface micrograph and surface chemistry analyses were employed to study the micromechanisms of fatigue failure and protein adsorption of the specimen surfaces. Rheological analysis indicated that the addition of HA to diluted bovine serum increased testing lubricant viscosity. HA concentrations of 2.22, 0.55, and 1.5 g/l closely matched the viscosity ranges reported for osteoarthritis, rheumatoid arthritic diseased joint fluid, and periprosthetic fluids respectively. Results showed that the addition of HA to standard diluted bovine serum lubricants, in concentrations similar to that of periprosthetic fluid, delayed crack initiation and crack growth during fatigue testing.

Animals↗

PubMed1995

Cushion form bearings for total knee joint replacement. Part 1: Design,friction and lubrication.

Cushion knee prostheses have been designed and constructed that produce approximately equal initial contact areas and theoretical film thicknesses compared with a conventional UHMWPE (ultra-high molecular weight polyethylene) joint. These compliant bearings had a flat tibial component which imposed fewer biomechanical constraints and allowed a greater range of movement. Friction experiments have been carried out on a pendulum simulator apparatus. The results showed that the cushion knee joints operated just within the mixed lubrication regime, but that they benefited from a substantial measure of fluid film lubrication. Microelastohydrodynamic lubrication was effective in preserving low friction and thin but effective lubricating films.

Biomechanical Phenomena↗

PubMed1996

The influence of loading time and lubricant on the friction of articular cartilage.

Friction of cartilage on metal, metal on cartilage and cartilage on cartilage contact configurations, within a mixed lubrication regime, was measured using synovial fluid, Ringer's solution or with no lubricant present. The main test variable was the period of stationary loading which ranged from 5 s to 45 min, prior to sliding and consequently measuring friction. The coefficient of friction rose gradually with increasing stationary loading time, up to a value of approximately 0.3 at 45 min for all the contact configurations. Following the re-application of load, after short periods of load removal, friction was also found to drop sharply. The flow of liquid in the biphasic cartilage and load carriage by the fluid phase was highlighted as being an important factor in reducing friction within the mixed or boundary lubrication regime. Movement of the contact zone over the cartilage counterface ensured very low friction as the slider moved over fully hydrated cartilage. For the cartilage--cartilage contacts synovial fluid significantly reduced friction compared to Ringer's solution. This was attributed to an effective boundary lubrication action, which was not as effective for the cartilage--metal contacts.

Animals↗

PubMed2001

[Discussion on the lubrication mechanism of natural and artificial human joints].

The lubrication mechanism of natural and artificial human joints was discussed in this paper. The history of joint lubrication research was reviewed briefly. Some key problems in joint lubrication were addressed. The clinical use of results obtained in studies of joint lubrication mechanism was also discussed in the paper.

Biomechanical Phenomena↗

PubMed2004

Effectiveness of lubrication of endotracheal tube cuff with chamomile-extract for prevention of postoperative sore throat and hoarseness.

PURPOSE OF THE STUDY: To determine the efficacy of lubrication of the endotracheal tube cuff with Chamomile extract (Kamillosan M) before intubation on postoperative sore throat and hoarseness. MATERIAL AND METHOD: The authors randomly assigned 161 patients ASA (American Society of Anesthesiologists) physical status I, II elective surgical, orthopedic, gynecological or urological into 2 groups. The study group received 10 puffs of total 370 mg of Chamomile extract (Kamillosan M spray) lubricated at cuff of endotracheal tube while the control group did not receive any lubrication before intubation. Standard general anesthesia with tracheal intubation was given in both groups. Sore throat and hoarseness were recorded in post anesthetic care unit and at 24 h after operation. RESULTS: One hundred and sixty-one ASA physical status I, II elective surgical patients were recruited. Forty one out of 81 patients (50.6%) in the Chamomile group, scored no postoperative sore throat in the post-anesthesia care unit compared with 45 out of 80 patients (56.3%) in the control group p=0.386. Postoperative sore throat and hoarseness both in the postanesthesia care unit and at 24 h postoperation were not statistically different. There was no statistically significant relationship between sore throat or hoarseness and postoperative nausea or vomiting, ASA physical status, gender, history of smoking, grade of laryngoscopic view, number of intubation attempts, condition during intubation, use of oral airway and couching during extubation. CONCLUSION: Lubrication of endotracheal tube cuff with Chamomile extract spray before intubation can not prevent post operative sore throat and hoarseness.

Adult↗

PubMed2005

The effect of experimental cartilage damage and impairment and restoration of synovial lubrication on friction in the temporomandibular joint.

AIMS: To evaluate how the frictional coefficient of the porcine temporomandibular joint (TMJ) is affected by an impairment of the synovial lubrication produced by an experimental abrasion of the articular cartilage and the application of hyaluronic acid (HA) with different molecular weights to the abraded cartilage surfaces. METHODS: Erosion of the articular cartilage was produced by scouring it with sandpaper. Impairment and restoration of synovial lubrication were modeled by washing the joint space with phosphate-buffered saline (PBS) and by the application of HA with different molecular weights. After measuring the frictional coefficients in the intact TMJs (n = 10), the effects of washing with PBS, sandpaper scouring, and the application of HA were subsequently examined. RESULTS: The mean frictional coefficient in the intact joint was 0.0154 (SD 0.0043). After PBS washing and sandpaper scouring, it increased significantly to 0.0235 (SD 0.0052) and 0.0520 (SD 0.0088), respectively. Subsequent application of HA resulted in a significant decrease (43% to 56%) of the frictional coefficient. Observations by scanning electron microscopy showed that after sandpaper scouring, the superficial cartilage layer was disrupted and inner layer was exposed, creating an irregular surface. CONCLUSION: Joint friction may increase by approximately 350% following an experimental scouring of the cartilage surface and impairment of synovial lubrication. Lubrication by means of HA decreased joint friction by approximately 50%.

Animals↗

PubMed2006

Effect of instrument lubricant on the cohesive strength of a hybrid resin composite.

OBJECTIVES: The purpose of this study was to evaluate the effect of instrument lubricant on the cohesive strength of resin composite layers. METHOD AND MATERIALS: Clear acrylic molds were filled with 3 increments of a hybrid resin composite using a metal instrument. The first increment (shade A2) was inserted to a height of 4 mm and light cured, followed by a 1-mm-high second increment (shade A1). The composite instrument was then wiped with 1 of 7 lubricants before insertion of a 1-mm-high third increment (shade A1): (1) isopropyl alcohol gauze, 70% v/v (AL); (2) acetone (AC); (3) Adper Single Bond Adhesive (SB); (4) One-Step Adhesive (OS); (5) D/E Bonding Resin (DE); (6) Scotchbond Multi-Purpose Adhesive (SP); (7) Tescera Sculpting Resin (TE). No lubricant was used in the control group (CT). A final 4-mm-high increment (shade A2) was inserted and light cured. The blocks were sectioned to obtain 48 sticks for each group. Sticks were fractured with an Instron machine. Statistics were computed using 1-way analysis of variance and Duncan's test. RESULTS: Outcomes were as follows (mean +/- SD, MPa; same letters indicate significant differences at a confidence level of 95%): TE = 96.7A +/- 17.8; SP = 93.6AB +/- 9.6; DE = 93.4AB +/- 16.2; OS = 91.9AB +/- 19.5; AC = 90.1ABC +/- 12.2; SB = 89.9ABC +/- 14.5; AL = 88.8BC +/- 16.8; CT = 84.7C +/- 8.3. CONCLUSIONS: Although the difference between Tescera Sculpting Resin and alcohol was statistically significant, Tescera Sculpting Resin is recommended only for indirect composite restorations. The lubricant used to reduce stickiness between the resin composite used for direct restorations and the composite instrument did not significantly reduce bond strengths.

2-Propanol↗

PubMed1994

[Harmful substances released during the thermal oxidative destruction of coolant lubricants].

The use of lubricated oils in industry is related to processes of dispersing, evaporation and thermo-oxidizing destruction. As a result, in the air is eliminated a complex vaporous-gas aerosol mixture, consisting of lubricated aerosols, vapours and volatile products of evaporation and products of thermo-oxidizing destruction. In the vapour-gas phase are identified hydrocarbons [saturated, unsaturated, aromatic and cyclic] oxygen- containing hydrocarbon derivatives-aldehydes, ketones, esters, alcohols] in some cases CO. HCL. The composition of the mixture depends on the type of the lubricated oils and on the specific technological operation. The detailed study of the components of the mixture is a prerequisite for determining the leading toxic substances and for correct evaluation of the exposure and professional risk in industries, allowing a course of destructive processes with the lubricated oils.

Air Pollutants, Occupational↗