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At least 325 records · Page 18Linked to original sources
PubMed1992

Posterior malleolar ankle fractures: an in vitro biomechanical analysis of stability in the loaded and unloaded states.

The use of internal fixation for posterior malleolar fractures remains controversial. This study assessed the contribution of the posterior malleolus/posterior tibiofibular (PM/PTF) complex to ankle stability in the loaded condition. Total plantarflexion and dorsiflexion, torsion, version, and drawer were measured with 15- and 70-kg loads before and after creation of posterior malleolar fractures that measured 25% of the distal articular surface. After internal fixation, specimens were retested. Fractures caused significant increases with internal rotation and posterior drawer at 15- and 70-kg loads in the neutral position. External rotation, anterior drawer, and dorsiflexion increased at 15-kg load. Fixation increased stability of fractured specimens, but not significantly. Fractures of the PM/PTF ligament complex may lead to excessive internal rotation and posterior instability in the loaded state.

Ankle Injuries↗
PubMed1990

[Experimental study on carbon fiber reinforced plastic plate--analysis of stabilizing force required for plate].

Plates currently in use for the management of bone fracture made of metal present with various problems. We manufactured carbon fiber reinforced plastic (CFRP) plates from Pyrofil T/530 puriplegs overlaid at cross angles of +/- 10 degrees, +/- 20 degrees, and +/- 30 degrees for trial and carried out an experimental study on rabbit tibiofibular bones using 316L stainless steel plates of comparable shape and size as controls. The results indicate the influence of CFRP plate upon cortical bone was milder than that of stainless steel plate, with an adequate stabilizing force for the repair of fractured rabbit tibiofibular bones. CFRP has the advantages over metals of being virtually free from corrosion and fatigue, reasonably radiolucent and able to meet a wide range of mechanical requirements. This would make CFRP plate quite promising as a new devices of treating fracture of bones.

Animals↗
PubMed1986

[Analysis and stability of propiverine hydrochloride (Mictonorm)].

In acid, neutral and alkaline solution the hydrolytic degradation of the spasmolytic agent Mictonorm (1) was determined. As degradation products ester- and/or ether fragments (2-5), benzophenone (6) and a compound X (7) were identified. In comparison N-Methylpiperidinyl(4)-benzilate (2) and benzilic acid (3) were also investigated in the isothermal quick-assay test. The test showed that the ether bound in 1 was hydrolyzed before the ester group. The compounds 5-7 are formed also direct from 3.

Benzilates↗
PubMed1983

[Analysis and stability of suxamethonium chloride. 2: Study of various factors in the stability of suxamethonium chloride injection solutions].

The packing material (glass ampoules and plastic disposable syringes) and the degree of purity of the active agent do not affect the stability of injectable suxamethonium chloride solutions. In contrast to this, the stability was markedly improved by lowering the temperature of storage. Injectable suxamethonium chloride solutions may be stored in plastic disposable syringes.

Chemistry, Pharmaceutical↗
PubMed1983

[Analysis and stability of atropine sulfate and scopolamine hydrobromide. 2. Quantitative determination of the alkaloid in its decomposition product; 79. contribution to problems concerning the use of plastic containers for liquid pharmaceuticals].

The authors describe a method which permits, after thin-layer chromatographic separation and elution by means of the Eluchrom apparatus, to determine the tropane alkaloids and apoatropine in the presence of their decomposition products using tropaeolin 00. The recommended method has proved to be superior to other elution variants with regard to accuracy and reproducibility. Detectable amounts (microgram/ml): atropine, 0.4-4.0; scopolamine, 1.2-7.2; apoatropine, 0.8-3,2.

Atropine↗
PubMed1983

[Analysis and stability of atropine sulfate and scopolamine hydrobromide. 3: Studies on the stability of tropane alkaloids; 80: contribution to problems in the use of plastic containers for liquid pharmaceuticals].

On evaluating their investigations, the authors discuss the degradation mechanism of tropane alkaloids in aqueous solution. As evidenced by competitive and consecutive reactions (hydrolysis, dehydration, dimerization), the degradation mechanism is characterized by a complicated course. Apart from temperature, a series of other factors, above all the pH value, exerts a considerable effect on the stability of both the alkaloids. Unbuffered solutions are more stable than buffered ones. The isothermal short-time test is not suitable for stability prediction. In the long-time test it was found that unbuffered aqueous atropine sulphate solutions still contained 90% of their initial drug content after 18 months' storage in low-density polyethylene containers at 20 degrees C. Scopolamine hydrobromide solutions showed an almost analogous behaviour. Of the container materials tested, low-density polyethylene bottles have been found to be best suited.

Atropine↗
PubMed1982

[Analysis and stability of suxamethonium chloride. 1. Detection and quantitative determination of the intact active agent with its degradation products].

The authors developed methods permitting to follow the course of degradation in injectable solutions of suxamethonium chloride. The qualitative detection of the active agent in the presence of degradation products is achieved by thin-layer chromatography and spraying with Dragendorff's reagent and bromocresol green indicator solution. The same separation technique may be used for determining with sufficient accuracy the intact agent in the eluate, using the method of Okken and Haas. Furthermore, a modified Draganic procedure (which is based on the spectrophotometric determination of the hydrolysis products succinic acid monocholine chloride and succinic acid as a Cu-benzidine complex) is suited for estimating the degree of degradation. No previous separation is required because the molar extinction efficients of the monoester and of the acid are in agreement, so that the degree of degradation can be calculated from the sum of the molar concentrations. The value of these methods is demonstrated by analyzing experimental mixtures of the intact agent and degradation products.

Drug Stability↗
PubMed1994

L4-5 isthmic spondylolisthesis. A biomechanical analysis comparing stability in L4-5 and L5-S1 isthmic spondylolisthesis.

The authors have previously reported that the L4-5 isthmic spondylolisthesis lesion often progresses more than the L5-S1 lesion in adult patients. This biomechanical study compares the in vitro stability of the L4-5 isthmic spondylolisthesis lesion compared with the L5-S1 isthmic lesion. The authors also analyzed the role of the L5 iliolumbar ligament as a contributing factor to stability. Six fresh frozen human cadaveric specimens (L4 to the sacrum including the iliolumbar ligamentous complex) were tested by applying 10 Nm flexion-extension moments. Sagittal plane motion was measured with the specimens intact and after sequential transection of the pars interarticulares at L4 and L5 and finally with the iliolumbar ligaments cut at L5-S1. L4-5 and L5-S1 both showed significant increases in rotation with the pars defect compared with normal (L4-5 = +2.0, L5-S1 = +3.2 degrees). Decreased translation of L5-S1 occurred with pars defect at this level. There were no significant differences at the L5-S1 level after sectioning of the iliolumbar ligament. Calculating the percentage difference from normal, L4-5 with a pars defect exhibited significantly greater relative motion compared with L5-S1 with the same defect; 12% more rotation, 33% more shear, and 43% more axial translation. The iliolumbar ligament did not appear to contribute to these differences because there was no significant change in the L5-S1 kinematics after its transection. These results support the hypothesis that L4-5 pars defects are more unstable than L5-S1 lesions. The iliolumbar ligament could not be implicated as the major contributing factor in these differences.

Biomechanical Phenomena↗
PubMed1995

Phase plane analysis of stability in quiet standing.

We analyzed the standing balance control of 11 healthy subjects and 15 subjects with bilateral vestibular hypofunction (BVH) using phase plane (velocity versus displacement) plots. We hypothesized that maintaining postural stability requires control of both the position and momentum of the center of gravity (CG) and infer that it is advantageous to use both velocity and displacement data to characterize balance control. Phase plane plots provide insight into this dynamic aspect of balance control. We evaluated phase plane plots based on whole body CG and center of pressure (CoP). We varied stability by altering the base of support and visual information. Three different foot placements were used: feet wide apart, feet together, and semitandem stance. Feet together standing was performed with eyes open and with eyes closed. The phase plane plots show changes in stability as base of support is altered or visual input is removed and reveal stability differences between the control and BVH groups. The root mean square variance of velocity and displacement was used to quantify the phase plane information. This parameter showed significant differences between activities and between groups. We conclude that phase plane plots that combine displacement and velocity information are more useful in characterizing balance control than displacement or velocity alone.

Gravitation↗
PubMed1995

Economic and quality of life outcomes: the four-step pharmacoeconomic research model.

Increasingly, economic data are being considered in formulary decisions. In oncology, pharmacoeconomic evaluations are essential to help decision makers weigh the associated costs and outcomes of competing chemotherapeutic interventions. In this article, we present a four-step pharmacoeconomic research model that can be customized for specific provider or payer systems. The model encompasses problem identification, clinical management analysis, three pharmacoeconomic analyses (cost consequence, expected cost, and cost effectiveness), and a sensitivity analysis--the rank order stability analysis (ROSA)--to validate the findings.

Antineoplastic Agents↗