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PubMed2006

The effects of stability ball training on spinal stability in sedentary individuals.

Stability ball training (SBT) is believed to improve spinal stability (SS) and could reduce the risk of back pain in sedentary individuals. The purpose of this study was to examine the effects of SBT on SS. Twenty sedentary individuals were randomly assigned to either an experimental group that performed SBT twice per week for 10 weeks or to a control group. Differences between groups were assessed by analysis of variance (ANOVA) with repeated measures. The experimental group improved significantly (p < 0.05) on the static back-endurance test from pretest (149.3 +/- 72.3 seconds) to posttest (194.6 +/- 56.7 seconds) and the side bridge test from pretest (45.4 +/- 39.4 seconds) to posttest (71.3 +/- 59.7 seconds). Back endurance for the control group did not change from pretest (123.4 +/- 64.9 seconds) to posttest (87.5 +/- 40.2 seconds), nor did the results of the side bridge test change for this group from pretest (41.8 +/- 26.4 seconds) to posttest (51.6 +/- 35.9 seconds). These findings illustrate that SBT may provide improvements in SS within this population. Practitioners might use SBT exercises where the position of the spine is maintained during the early phases of back-pain prevention programs. This type of programming might be beneficial to individuals who spend a good deal of time sitting (i.e., in corporate fitness programs) or for individuals who are prone to back pain and have been cleared to exercise. Also, the side bridge and static back endurance assessments may be good choices for measuring SS in field settings.

Adult↗
PubMed1985

Stability of the shoulder joint. Cadaver study of stabilizing structures.

In 10 cadaver shoulder joints, the increments in external rotation were measured after successive cutting of the anterior stabilizing structures while a constant external torque was applied to the humerus, abducted in the scapula plane. The subscapularis muscle prevented anterior subluxation in the lower range of abduction. As abduction increased, the lower part of the capsule was the most important stabilizing structure. The findings suggest that it may be possible to perform more selective repairs in the treatment of recurrent anterior instability.

Biomechanical Phenomena↗
PubMed1993

An in vitro biomechanical study of the static stabilizing effect of lateral prophylactic knee bracing on medial stability.

We attempted to determine if the selected lateral prophylactic knee braces (ie, Anderson Knee Stabler-101W, Don Joy-PKG and McDavid Knee Guard) were effective at stabilizing the medial collateral ligament against valgus loading to the knee joint. We tested 23 volunteer subjects under each of three braced conditions, plus a nonbraced condition. Applying stress to the lower leg of the subjects, we measured and recorded the linear displacement of the tibia in abduction and/or adduction. We analyzed the data, using a repeated measures ANOVA. There were no differences between the bracing conditions. We concluded that the three knee braces were not effective at stabilizing the knee joint from a static valgus force.

Journal Article↗
PubMed2006

Posterior cruciate ligament-retaining, posterior stabilized, and varus/valgus posterior stabilized constrained articulations in total knee arthroplasty.

The degree of constraint required to achieve immediate and long-term stability in total knee arthroplasty (TKA) is frequently debated, with most authors favoring the least degree of constraint possible. There are generally three surgical biases in TKA involving the posterior cruciate ligament (PCL): surgeons who always retain the PCL, those who always sacrifice it, and those who decide to retain or sacrifice the PCL based on pathology. Surgeons who retain the PCL argue that it is one of the strongest ligaments about the knee and affords inherent stability to the TKA, whereas the proponents of PCL sacrifice argue that the PCL is compromised as a result of the degenerative process. With the pathologic approach, the diseased state of the knee at the time of arthroplasty dictates whether the PCL is retained or sacrificed. In patients without significant varus or valgus malalignment and without significant flexion, contracture may be addressed by retaining the PCL, whereas the PCL should be removed in patients with these deformities. Certain disease processes are more amendable to PCL sacrifice, such as end-stage degenerative joint disease secondary to rheumatoid arthritis, previous patellectomy, previous high tibial osteotomy or distal femoral osteotomy, and posttraumatic arthritis with disruption of the PCL. The degree of constraint of the articulation in TKA should be dictated by the degree of disease and associated deformity. A pathologic approach is rational and has clinically based evidence of success. Surgeons should have the option of modifying the degree of constraint at the time of surgical intervention. Currently, many TKA implant systems offer such flexibility.

Arthroplasty, Replacement, Knee↗
PubMedDate not supplied

[Quantum-chemical study of the relative stability of nucleic acid bases protonation stability].

The influence of protonation on the relative stability of matched and mismatched nucleic base pairs was considered. Protonation of a base has a significant effect on the bond energy and, in some cases, on the geometry of pairs. It was shown that protonation of guanine, adenine and uracil lead to an increased relative stability of matched pairs and, consequently, to decreased probability of mutations. Protonation of cytosine reduced the difference in energy formation of GC and AC complexes.

Adenine↗
PubMed1987

Preparation and stability of low-cost liquid quality-control serum stabilized with ethanediol.

The use of quality-control serum to monitor laboratory performance is an essential part of any health laboratory. However, laboratories in many countries are disadvantaged because of the non-availability or high cost of commercial quality-control sera. Here we describe the stability of bovine serum stabilized with ethanediol, prepared at low cost by simple techniques that are available in most laboratories.

Animals↗
PubMed1977

The stability of glutardialdehyde-stabilized 35-heparinized surfaces in contact with blood.

Heparin can be bound to polymer surfaces by precipitation of an ionic heparin-amine complex which can be stabilized against dissolution by treatment with glutardialdehyde. The aim of this investigation was to study the degree and course of desorption of heparin from such a heparinized surface on contact with blood. This desorption must be considered when analysing the interaction between the heparinized surface and blood. Different heparinized surfaces were prepared by using 35S-labelled heparin, and the desorption of heparin on exposure in vitro to citrated plasma or heparinized blood as well as during exposure at in vivo conditions was quantified. During in vitro experiments, the glutardialdehyde stabilized surface became stable with no further desorption of heparin after an initial loss of about 3% of the initial surface-bound heparin. Under in vivo conditions, there was an initial loss of about 12%. There was no further loss from surfaces inserted into the circulation of the dog for seven days as compared to those inserted for one hour.

Adsorption↗
PubMed1981

Hip endoprosthesis stabilization with a porous low modulus stem coating: factors influencing stabilization.

A polytetrafluoroethylene/vitreous carbon porous material has been investigated as an alternative to acrylic for hip endoprosthesis fixation. This material, which is mechanically fused to the endoprosthesis stem, has been shown to promote soft-tissue ingrowth. In 29 patients receiving a porous-coated Thompson endoprosthesis, stabilization of the porous-coated stem as observed by acceptable clinical results occurred in only about 50%. Stabilization of porous-coated endoprostheses is unsatisfactory for the following reasons: lack of press-fit, inadequate prosthetic design, infection, and technical difficulties. The major cause of 40% failure in this series was an initially inadequate press-fit.

Adult↗
PubMedDate not supplied

Stability of firefly luciferase in tricine buffer and in a commercial enzyme stabilizer.

A solution of firefly luciferase in AuthentiZyme Enzyme Stabilizer retains full activity when stored in an ice bath (0.5 degrees C) during one day. These solutions have the advantage that no additional protein (other than the luciferase) is present, which is desirable for proteolytic digestion and protein derivatization experiments. For longer-term experiments, firefly luciferase solutions in 0.05 mol/l Tricine buffer at pH 7.8, 10 mmol/l MgSO4, 1 mmol/l EDTA, and 1 mmol/l DTT which contain 100 micrograms/ml of bovine serum albumin are stable for 6 weeks if frozen and thawed only once.

Animals↗
PubMed1983

Prediction of stability in pharmaceutical preparations XX: stability evaluation and bioanalysis of cocaine and benzoylecgonine by high-performance liquid chromatography.

Specific, sensitive, reverse-phase high-performance liquid chromatographic (HPLC) assays of cocaine (I) and its hydrolysis products, benzoylecgonine (II) and benzoic acid (III), have been devised with analytical sensitivities as low as 15 ng/ml of plasma for I using spectrophotometric detection at 232 nm. Cocaine can be separated from its hydrolysis products by extraction at pH 7.5 with haloalkanes. Benzoylecgonine and benzoic acid can be extracted at pH 3.0 with 1-butanol. The evaporated residues were reconstituted in acetonitrile-water for HPLC assay. The assay was used to determine the stabilities of I and II in aqueous solutions, to establish log k-pH profiles at various temperatures, and to evaluate Arrhenius' parameters. Hydrolyses were by specific acid-base catalysis. Cocaine showed hydrogen and hydroxyl ion attack on protonated I with 40 and 90% proceeding through the benzoylecgonine route, respectively, as well as hydroxyl ion attack on neutral cocaine, with only 6% proceeding through the benzoylecgonine route. Cocaine is relatively unstable in the neutral pH range with a half-life of 5 hr in buffer at pH 7.25 and 40 degrees. Similar half-lives were observed in fresh dog plasma at 300 and 30 micrograms/ml, although one study at 0.5 microgram/ml indicated a doubling of the rate.

Buffers↗
PubMed1992

Alpha-helix stability in proteins. II. Factors that influence stability at an internal position.

The solvent-exposed residue Ala32 in the second alpha-helix of barnase was replaced by all other naturally occurring amino acids and the concomitant effects on the protein stability were determined. The results are assumed to reflect both the distinct conformational preferences of the different amino acids and also possible intrahelical interactions. The conformational preferences may be fully rationalized by invoking only a few physical principles. The results agree well with recently experimentally determined rank-order of helix-forming tendencies determined on a model peptide. There is very weak correlation between the results and the experimental host-guest values. There is a weak correlation between our results and the statistical helix propensities and a slightly better correlation with the positional-dependent statistical parameters of J. S. Richardson, and D. C. Richardson.

Amino Acid Sequence↗
PubMed1996

Sintering of partially-stabilized zirconia and partially-stabilized zirconia-hydroxyapatite composites by hot isostatic pressing and pressureless sintering.

In this study two sintering techniques, pressureless sintering (PS) and hot isostatic pressing (HIP), were used for comparing the sinterability of two yttria-partially-stabilized zirconia/hydroxyapatite (PSZ/HA) composites. Virtually dense ceramics were obtained using HIP at a maximum pressure of 160 MPa for 1 h at 1225 degrees C for both PSZ powders and their HA composites. The ceramic bodies, produced using PS at the same temperature as in the HIP process and higher, had densities from 80% to 97% of theoretical density, depending on the properties of the PSZ powders. FTIR spectra of composites sintered by HIP and PS at 1225 degrees C were compared, indicating a degradation of HA by PS but no degradation by HIP. The bending strength of HIPed ceramics was measured and found to be high. It is concluded that it is possible to produce dense PSZ/HA composites by the HIP or PS processes. For the PS, the reactivity of powders is the key factor during the densification. The HIP technique is the preferable technique for producing stable and dense HA-containing composites.

Biocompatible Materials↗
PubMed2006

A stability indicating assay method for cefuroxime axetil and its application to analysis of tablets exposed to accelerated stability test conditions.

Cefuroxime axetil is the esterified form of cefuroxime, injectable second generation cephalosporine antibiotic that can be given orally. Stereo and structural isomers of cefuroxime axetil (CA), anti-cefuroxime axetil (ACA) and Delta(3)-cefuroxime axetil (DCA), can be present in cefuroxime dosage forms as the process related impurities as well as possible degradation product. Sensitive and precise reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the determination of cefuroxime axetil in the presence of its degradation products in solid dosage forms. The RSD values for cefuroxime axetil, anti-cefuroxime axetil and Delta(3)-cefuroxime axetil of 1.80, 1.99 and 2.48%, respectively, indicated a good precision of the RP-HPLC method. Developed RP-HPLC method was sensitive with LOD = 0.08 microg mL(-1) and LOQ = 0.60 microg mL(-1) for anti-cefuroxime axetil and LOD = 0.06 microg mL(-1) and LOQ = 0.45 microg mL(-1) for Delta(3)-cefuroxime axetil. Holding studies were carried out on Ceroxim tablets, according to ICH regulation at 30 degrees C/60% relative humidity (RH) and 40 degrees C/75% RH for 1, 2, 3 and 6 months. The review data from the stability studies conducted, show the significant content change of Delta(3)-cefuroxime axetil.

Cefuroxime↗
PubMed2004

ICH guidance in practice: establishment of inherent stability of secnidazole and development of a validated stability-indicating high-performance liquid chromatographic assay method.

The degradation behaviour of secnidazole was investigated under different stress degradation (hydrolytic, oxidative, photolytic and thermal) conditions recommended by International Conference on Harmonisation (ICH) using HPLC and LC-MS. A stability-indicating HPLC method was developed that could separate drug from degradation products formed under various conditions. Secnidazole was found to degrade significantly in alkaline conditions, oxidative stress, and also in the presence of light. Mild degradation of the drug occurred in acidic and neutral conditions. The drug was stable to dry heat. Resolution of drug and the degradation products formed under different stress studies were successfully achieved on a C-18 column utilizing water-methanol in the ratio of 85:15 and at the detection wavelength of 310 nm. The method was validated with respect to linearity, precision (including intermediate precision), accuracy, selectivity and specificity.

Chromatography, High Pressure Liquid↗
PubMed2005

Establishment of inherent stability of stavudine and development of a validated stability-indicating HPLC assay method.

The present study describes degradation of stavudine under different stress conditions (hydrolysis, oxidation, photolysis and thermal stress), and establishment of a stability-indicating reversed-phase HPLC assay method. The drug was found to hydrolyse in acidic, neutral and alkaline conditions and also under oxidative stress. The major degradation product formed under various conditions was thymine, as evidenced through comparison with the standard and spectral studies (NMR, IR and MS) on the isolated product. Separation of drug, thymine and another minor degradation product was successfully achieved on a C-18 column utilising water-methanol in the ratio of 90:10. The detection wavelength was 265 nm. The method was validated with respect to linearity, precision (including intermediate precision), accuracy and specificity. The response was linear in the drug concentration range of 25-500 microg ml(-1). The mean values (+/-R.S.D.) of slope and correlation coefficient were 24256 (+/-0.679) and 0.9994 (+/-0.0265), respectively. The R.S.D. values for intra- and inter-day precision studies were <0.210 and <1%, respectively. The recovery of the drug ranged between 99.7 and 101.5% from a mixture of degraded samples. The method even proved to be affective on application to a stressed marketed capsule formulation.

Chromatography, High Pressure Liquid↗
PubMed1999

Stabilization of azadirachtin A in neem formulations: effect of some solid carriers, neem oil, and stabilizers.

Formulation of azadirachtin A on attapulgite, kaolinite, fuller's earth, hydrated calcium silicate, and fly ash revealed that it degraded to the tune of 70-95% on different solid carriers as compared to 56% in neem oil, during the 14 day heat storage studies at 54 +/- 1 degrees C in the laboratory. The degradation was reduced by 26-60% on different carriers by employing either anthraquinone or epichlorohydrin as stabilizer. Pyrogallol and hydroquinone enhanced the degradation. The cation exchange capacity and surface area of the carriers revealed a significant negative correlation with t(1/2) of azadirachtin A.

Chemistry, Pharmaceutical↗
PubMed2004

Liposome-stabilized oil-in-water emulsions as adjuvants: increased emulsion stability promotes induction of cytotoxic T lymphocytes against an HIV envelope antigen.

Protective or therapeutic immunity against HIV infection is currently believed to require both antibody and CTL responses against the envelope protein. In the present study, the adjuvant activity of a unique oil-in-water emulsion, in which liposomes containing lipid A (LA) and encapsulated antigen served as the emulsifying agent, was examined in mice using oligomeric gp140 (ogp140) derived from the HIV-1 envelope as the antigen. Emulsions rendered either highly stable or unstable by altering the ratio of liposomes to oil were used to examine the effect of stability of the emulsion on adjuvant activity. Stable and unstable emulsions had similar potencies for inducing both IgG antibodies to ogp140 and antigen-specific T-lymphocyte proliferation. Stable emulsions, but not unstable emulsions, induced antigen-specific CTL responses, possibly because of the depot effect of the stable emulsions. Furthermore, stable emulsions induced lower IgG2a/IgG1 ratios than the unstable emulsions. We conclude that stable liposomal oil-in-water emulsions provide an effective means of obtaining both antibody and CTL responses against an HIV envelope antigen.

AIDS Vaccines↗
PubMed2006

Limited mutagenesis increases the stability of human carboxypeptidase U (TAFIa) and demonstrates the importance of CPU stability over proCPU concentration in down-regulating fibrinolysis.

Procarboxypeptidase U [proCPU, thrombin-activatable fibrinolysis inhibitor (TAFI), EC 3.4.17.20] belongs to the metallocarboxypeptidase family and is a zymogen found in human plasma. ProCPU has been proposed to be a molecular link between coagulation and fibrinolysis. Upon activation of proCPU, the active enzyme (CPU) rapidly becomes inactive due to its intrinsic instability. The inherent instability of CPU is likely to be of major importance for the in vivo down-regulation of its activity, but the underlying structural mechanisms of this fast and spontaneous loss of activity of CPU have not yet been explained, and they severely inhibit the structural characterization of CPU. In this study, we screened for more thermostable versions of CPU to increase our understanding of the mechanism underlying the instability of CPU's activity. We have shown that single as well as a few 2-4 mutations in human CPU can prolong the half-life of CPU's activity at 37 degrees C from 0.2 h of wild-type CPU to 0.5-5.5 h for the mutants. We provide evidence that the gain in stable activity is accompanied by a gain in thermostability of the enzyme and increased resistance to proteolytic digest by trypsin. Using one of the stable mutants, we demonstrate the importance of CPU stability over proCPU concentration in down-regulating fibrinolysis.

Amino Acid Sequence↗