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At least 1,135 records · Page 63Linked to original sources
PubMed1996

Comprehensive gait analysis in posterior-stabilized knee arthroplasty.

Sixteen patients implanted with a posterior-stabilized prosthesis (Insall-Burstein PS II, Zimmer, Warsaw, IN) and 32 age-matched control subjects were evaluated by isokinetic muscle testing and comprehensive gait analysis at a mean 46 months following the index arthroplasty. The contralateral knee was normal in 13 patients and an asymptomatic total knee arthroplasty in 3 patients. No significant differences (P > .05) were found between the study and control groups in spatiotemporal gait parameters nor were there isokinetic strength deficits. A prolonged firing of the vastus medialis was observed in some patients. Knee range of motion during level walking and stair descent was decreased significantly (P < .05) in the study group. There was no significant difference for knee range of motion between the study and control groups during stair ascent. Spatiotemporal gait parameters in the total knee arthroplasty patients show no significant differences from the control subject at nearly 4 years after surgery. However, other gait abnormalities are present and cannot be accounted for on the basis of muscle weakness, abnormal phasic muscle activity, or inadequate knee range of motion. With reference to historic control subjects, the persistent gait abnormalities of patients implanted with posterior-stabilized prostheses (posterior cruciate substituting) are comparable to those of patients implanted with cruciate-retaining prostheses and superior to cruciate-sacrificing prostheses.

Adult↗
PubMed2002

Use of prior information to stabilize a population data analysis.

When modeling new data with a complex population pharmacokinetic/pharmacodynamic model, there may not be sufficient information to obtain estimates of all parameters. In this case information from previous studies can also be used to help stabilize estimation. Using simulated data, we explored three different ways to do this. (i) Some parameter values were fixed to estimates obtained from earlier data. (ii) The earlier data were combined with the current data. (iii) The objective function based on the current data was augmented by a penalty function expressing summary information obtained from the earlier data. This last method is similar to the use of a Bayesian prior. It may be particularly useful when either the combined data set of method (ii) is very large and leads to large computation times or when the early data are not readily available. With this method, two different types of penalty functions were used. With our examples, the three methods all resulted in stabilized estimation. Methods (ii) and (iii) gave similar results for parameter and standard error estimation, especially with respect to fixed effects parameters. For hypothesis testing, results obtained with method (i) are very problematic. There are also problems with the results obtained with method (iii), but they are much less severe, and when the design for the earlier data is known, they can be corrected by using a computer-intensive simulation test procedure.

Algorithms↗
PubMed2001

Local structure analysis of Ti species stabilized in ion exchangeable layer solids by x-ray absorption spectroscopy.

Nano-sized titanium dioxides are incorporated into the interlayer spaces of ion-exchangeable layered perovskites, H(1-x)Ca2(x)La(x)Nb3O10 (x=0.0-0.75), by replacing the interlayer protons with positively charged TiO2 nano-sol particles or basic titanium glycolate complex (titanatrane). Powder X-ray diffraction analysis. UV-Vis absorption spectroscopy, thermogravimetric analysis, and N2 adsorption-desorption isotherm measurements show that quantum sized TiO2 particles are stabilized in between perovskite lattices to form micropores (S(BET) = 37-110 m2/g). X-ray absorption spectroscopy at the Ti K-edge was used for investigating the local environment around Ti atoms constituting the interlayer pillars. According to the XANES spectra, the 'as-pillared' Ti species have the same local environments with those of precursory species, which subsequently converted into TiO2 clusters with rutile and anatase-like local structures when TiO2 nano-sol particles and titanatrane are used as pillaring species. respectively. It is also found that the local environment of TiO2 remains almost constant irrespective of the layer charge density, while the TiO2 pillar content and the microporosity increase with the latter.

Journal Article↗
PubMed1979

Stability-indicating sulfa drug analysis using high-performance liquid chromatography.

Sensitive and efficient methods for sulfonamide determination as single entities and in combination with other drug substances in pharmaceutical dosage formulations were developed using high-performance liquid chromatography. These stability-indicating procedures involved a nitrile bonded phase column and nonaqueous mobile phases having diverse polarities. Sample potency was determined using peak height measurements. The methods may be used to determine trace sulfonamide quantities because detection limits are in the nanogram range.

Chemical Phenomena↗
PubMed2003

Finite element analysis of the initial stability of ankle arthrodesis with internal fixation: flat cut versus intact joint contours.

OBJECTIVE: Qualitative comparison of the initial stability provided by two joint preparation techniques and various screw configurations in ankle arthrodesis, using the finite element method.Design. A three-dimensional model of a healthy ankle was developed from computed tomography images. Two groups of models were built, one with the joint contours resected to produce flat surfaces, and the second with the joint contours preserved. In each case, a variety of screw orientations were examined. BACKGROUND: Despite the improved results of ankle arthrodesis, failure rates due to non-union are still reported. The initial stability of the arthrodesis construct seems important in the final outcome of the fusion. METHODS: Non-linear contact finite element analyses were performed in the arthrodesis constructs subjected to internal/external torsion and dorsiflexion. Micromotions at the bone-to-bone interface were calculated for frictionless and Coulomb friction contact, and compared for the two joint preparation techniques and screw configurations. RESULTS: Overall lower peak micromotions were predicted when preserving the joint contours both in torsion and dorsiflexion. For both preparation techniques, the lowest micromotions tended to occur with the screws inserted at 30 degrees with respect to the long axis of the tibia, crossing above the fusion site. Inclusion of friction in the models caused a general decrease on the magnitude of the micromotions as compared to the frictionless case, but did not affect the ranking of the models. CONCLUSIONS: The finite element method can be used as a qualitative tool to study the initial stability of ankle arthrodesis, overcoming the difficulties of measuring bone-to-bone interface micromotions experimentally. Better initial stability was predicted for ankle arthrodesis when the joint contours were preserved rather than resected. Crossing the screws above the fusion site at a steeper angle also tended to increase the stability at the fusion site. RELEVANCE: Finite element analyses can help during the pre-operative planning of ankle arthrodesis. When bone density is not compromised, preserving the joint contour and inserting the screws at less than 45 degrees to the long axis of the tibia, crossing over the arthrodesis site, may offer better initial stability.

Ankle Joint↗
PubMed2000

Elucidation of determinants of protein stability through genome sequence analysis.

Sequences of putative soluble proteins from complete genomes of eight thermophiles and 12 mesophiles were analyzed to gain insight into determinants of protein thermostability. The predator algorithm was used to assign secondary structures to each protein sequence. Based on simple statistical tests, a set of stabilizing factors was identified. These include reduced protein size, increases in number of residues involved in hydrogen bonding, beta-strand content and helix stabilization through ion pairs. There are also significant increases in the relative amounts of charged and hydrophobic beta-branched amino acids and decreases in uncharged polar amino acids in proteins from thermophiles relative to mesophilic organisms. Factors such as the relative proportion of residues in loops, proline and glycine content and helix capping do not appear to be important.

Amino Acids↗
PubMed1998

Study of NADH stability using ultraviolet-visible spectrophotometric analysis and factorial design.

The chemical stability of nicotinamide adenine dinucleotide coenzyme (NADH/NAD+) and its derivatives (NADPH/NADP+) was investigated using changes in the UV-visible absorption spectra of these compounds. The spectra of cofactor (reduced form) were monitored at 340 nm wavelength in different buffers, showing a faster degradation in phosphate buffer. This was assigned to the adduct formation between phosphate and NADH (pyridine ring). The three-factor-two-level factorial design study evaluated the contributions: buffers (phosphate and Pipes 0.1 M), pH's (6.8 and 7.8), and temperature (25 and 30 degrees C). The freshly prepared aqueous solutions of coenzyme were analyzed after 40 min under the different conditions (eight assays in triplicate) of the experiment. The main observed effects of the NADH oxidation were, in increasing order, pH, temperature, and buffer without appreciable interactive effects. Therefore, it was verified that the better conditions for cofactor use were alkaline media employing Pipes buffer or its derivatives and low temperatures.

Buffers↗
PubMedDate not supplied

Radiohumeral stability to forced translation: an experimental analysis of the bony constraint.

Radiohumeral stability to forced translation was experimentally analyzed in 8 osteocartilaginous joint preparations. The joints were dislocated in 8 centrifugal directions at 12 different combinations of joint flexion and rotation while a constant joint compression force of 23 N was applied. Stability was measured as the maximum resistance to translation. On average, the specimens could resist a transverse force of 16.4 N (range, 13.0-19.1 N). Stability was greater in some directions than in others. Rotating the joint changed the direction at which stability was greatest, whereas joint flexion did not. In supination, the greatest stability was observed for anteromedial dislocations, in neutral rotation for posteromedial dislocations, and in pronation for posterolateral dislocations. The findings from this study indicate systematic variations in wall height around the radial head concavity as well as individual variations in joint constraint. This may have implications for the treatment of conditions involving radiohumeral joint dislocation.

Cadaver↗
PubMed1993

Does migration stabilize local population dynamics? Analysis of a discrete metapopulation model.

A discrete model for a metapopulation consisting of two local populations connected by migration is described and analyzed. It is assumed that the local populations grow according to the logistic law, that both populations have the same emigration rate, and that migrants choose their new habitat patch at random. Mathematically this leads to a coupled system of two logistic equations. A complete characterization of fixed point and two-periodic orbits is given, and a bifurcation analysis is performed. The region in the parameter plane where the diagonal is a global attractor is determined. In the symmetric case, where both populations have the same growth rate, the analysis is rigorous with complete proofs. In the nonsymmetric case, where the populations grow at different rates, the results are obtained numerically. The results are interpreted biologically. Particular attention is given to the sense in which migration has a stabilizing and synchronizing effect on local dynamics.

Animals↗
PubMed1996

Survivorship analysis of the Kinematic Stabilizer total knee replacement: a 10- to 14-year follow-up.

The Kinematic Stabilizer is a posterior-cruciate-substituting design of total knee replacement. We have reviewed 109 primary total knee replacements in 95 patients at a mean follow-up time of 12.7 years (10 to 14). We used survival analysis with failure defined as revision of the implant. This gave a cumulative survival rate of 95% (95% CI +/- 5%) at ten years and (87% +/- 10%) at 13 years. These results from an independent centre confirm the value of an established design of cemented total knee replacement and question the wisdom of the introduction of modifications and new designs without properly controlled trials.

Adult↗
PubMed1999

Major bone transplantation in total knee arthroplasty: a 2- to 9-year radiostereometric analysis of tibial implant stability.

Eight total knee arthroplasties involving major bone grafting to repair noncontained defects of the proximal tibia were studied. In all knees, autologous bone was used. Cement was used for implant fixation. At follow-up evaluation 5 years after surgery, 7 knees had excellent results, and 1 had fair results; the mean Hospital for Special Surgery score was 84. Radiostereometric analysis showed a mean migration of 0.5 mm (range, 0.2-1.5 mm). None of the knees in which major structural autologous bone grafting was used showed increased micromotion of the adjacent tibial implant.

Aged↗
PubMed1997

Stability enhancement for peptide analysis by electrospray using the triple quadrupole mass spectrometer.

Electrospray ionization sources, used with triple quadrupole mass spectrometers from PE/Sciex (API III+), Micromass (Quattro II), and Finnigan (TSQ 7000), were modified with a 35-gauge stainless steel needle. The dimensions of the needle were 63 microm i.d. by 145 microm o.d. with variable length, depending on the specific instrument. This modification led to enhanced signal stability, improved signal/noise ratios, and lowered sample consumption for a wide range of peptides. Stable baselines were observed with flow rates in the range of 50 nL/min to 5 microL/min. An alternative design, based on a metal wire housed within a fused silica capillary, led to the most stable signals of all during infusion, but caused excessive peak broadening with capillary chromatography. The Finnigan interface was further modified with an external postcolumn addition tee, used in conjunction with capillary liquid chromatography columns of 30 and 50 microm internal diameter. The best results with the modified Finnigan interface were acquired using the 50-microm column at a flow rate of 150 to 200 nL/min.

Factor VII↗
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

Analysis of the genetic stability of Eucalyptus globulus Labill. somatic embryos by flow cytometry.

Flow cytometry was used to measure the nuclear DNA content of Eucalyptus globulus Labill. somatic and zygotic embryos and leaves in order to determine if somatic embryogenesis induces DNA content and ploidy changes in this species. Mature zygotic embryos derived from open-pollination orchard families were collected from a location in the centre of Portugal. One group was kept for nuclear DNA content and ploidy analysis, and the other group was used for establishing embryogenic cultures. Mature zygotic embryos were grown on Murashige and Skoog (MS) medium supplemented with 3% (w/v) sucrose and 3 mg l(-1) alpha-naphthaleneacetic acid (NAA) for 3 weeks and then transferred to MS medium without growth regulators. Globular somatic embryos from approximately 8-month-old embryogenic cultures were used in the assay. DNA ploidy levels and the nuclear DNA content of mature zygotic embryos, somatic embryos and leaves from the mother field tree were determined using flow cytometry combined with propidium iodide staining. Zygotic embryos had a nuclear DNA content of 1.32 pg/2C, somatic embryos had a nuclear DNA content of 1.39 pg/2C and leaves from the field tree had a nuclear DNA content of 1.40 pg/2C. The values estimated for the somatic embryos and mother plant did not differ statistically from each other (P < or = 0.05), but both differed from those of the zygotic embryos (P < or = 0.05). These results clearly indicate that no changes were induced during the embryogenic process. However, the differences found between the field plants and zygotic embryos did suggest that some aspects must be evaluated carefully, as propidium iodide fluorescence may potentially be influenced by the presence of secondary compounds (e.g. anthocyanins, tannins) in E. globulus somatic embryos and mature leaves. Therefore we believe that the somatic embryogenesis methodology used did not induce major genetic changes in the somatic embryos and that our primary goal of "true-to-type" propagation was assured.

Analysis of Variance↗
PubMed1989

Study on the behavior management of children at dental treatment. Various factors affecting the frequency of training.

Search was made using quantification method of the first and second type to search the factors affecting the frequency of training, and to estimate it. The following conclusions were led; 1. Factors giving large effect on the decision of the frequency of training were 'Frankl classification', 'ages at the initial examination' and 'if children have any experience of dental treatment or not'. 2. With the factors concerned with educational environments including mothers, 'number of brothers and sisters', 'mother's educational history' and 'if mothers works or not' showed high correlation. 3. Among the factors concerned with character analysis, 'emotional stability' 'if children can control themselves or not' gave much effect. 4. As the factors to estimate the frequency of training, the reliable factors include 'Frankl classification', 'ages at initial examination', and 'sexes'. 5. With the factors concerned with educational environments including mothers, 'mother's educational history', 'number of brothers and sisters' 'birth order' were highly reliable. 6. With the factors concerned with character analysis, 'emotional stability', 'if children fants are degenerative or productive' showed high reliability. 7. Multiple correlation coefficient for all the 27 factors was 0.823, which was found to be highly reliable for the estimation of the frequency of training.

Behavior Therapy↗
PubMed1989

[Study on the behavior management at dental treatment. Research of various factors affecting the frequency of training by multivariate analysis].

A Search was made using quantification methods of the first and second type to discover the factors affecting the frequency of training, and to estimate it. The following conclusions were obtained; 1. Factors having a large effect on the decision of the frequency of training were the Frankl classification, ages at the initial examination and if children have any experience of dental treatment or not. 2. With the factors concerned with educational environments encompasing mothers, number of brothers and sisters, the mother's educational history and wether the mothers work or not high correlation was shown. 3. Among the factors concerned with character analysis, emotional stability, if children can control themselves or not had considerable effect. 4. As for the factors for estimating the frequency of training, the reliable factors include Frankl classification, ages at initial examination, and sexes. 5. With the factors concerned with educational environment including mothers, the mothers' educational history, the number of brothers and sisters, birth order were highly reliable. 6. With the factors concerned with character analysis, emotional stability, if children are degenerative or productive showed high reliability. 7. Multiple correlation coefficient for all the 27 factors was 0.823, which was found to be highly reliable for the estimation of the frequency of training.

Behavior Therapy↗