[Reply to criticism of "Analysis of the lateral stability of protofibrils in the A-disk of striated muscle"].
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Biophysical Phenomena↗
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Results for “Stability analysis”
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[Method of quantitative analysis of phosphorus and stabilizing its content in biological and chemical assays].
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Indicators and Reagents↗
[Clinical and radiological analysis of lumbar spine stability after hemilaminectomy and laminectomy in cases of lumbar disk excision with simultaneous interbody fusion].
108 patient were operated on the Neurosurgical Department of the Military Clinical Hospital in Wrocław since 1989 till 1991. The stability of the lumbar spine after hemilaminectomy and laminectomy with disc excision and interbody fusion was analysed. The period after operation ranged from 6 months to 2 years. Signs of clinical and radiological instability were the base of the study. Respective segmental motions in maximal ante- and retroflexion were calculated. Horizontal intercorporal dislocation was assessed. No signs of instability where found in the analysed material. The results after laminectomy and hemilaminectomy were similar. The failures were not caused by instability.
Adult↗
Posterior decompression and stabilization for spinal metastases. Analysis of sixty-seven consecutive patients.
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Bone Screws↗
[Quantitative evaluation of the stability of antibody production by human-mouse hybridoma clones with flow cytometry analysis].
The paper described a method of quantitative stability analysis of antibody production by hybridoma clones with flow cytometry (FACS). Through FACS analysis the frequency of antibody-negative variants was measured. The rate of generation of antibody-negative variants/cell/generation (mu) could be calculated through Luria-Delbrück fluctuation analysis. The results showed that the value of mu was correlated to the antibody production of hybridoma clones: the larger was the mu value, the more unstable was the antibody production by the hybridoma clones. The experimental results suggested that the clone was stable if its mu value was on the magnitude of 10(-3), while the clone was not stable if its mu value was on the magnitude of 10(-2). According to requirements of single cell for FACS analysis and presence of a variety of methods for dispersing cell aggregates to single cells, the authors regard that this method is fully suitable for analysis of cells in suspension or even in the form of aggregate.
Animals↗
Early versus delayed stabilization of pediatric femur fractures: analysis of 387 patients.
OBJECTIVES: To assess the effect of timing of femur fracture stabilization on pulmonary complication rates in pediatric trauma patients. DESIGN: Retrospective review. SETTING: Level I trauma center. PATIENTS: Three hundred eighty-seven previously healthy patients from zero to fifteen years of age with traumatic diaphyseal femur fractures. INTERVENTION: Femur fracture stabilization: early (less than twenty-four hours after injury) in 213 patients and late in 174 patients. MAIN OUTCOME MEASUREMENTS: Age, sex, GCS (Glasgow Coma Score), AIS/ISS (Abbreviated Injury Score/Injury Severity Score), timing of fracture stabilization, duration of mechanical ventilation, intensive care unit stay, and hospital stay were recorded. Pulmonary complications, including pneumonia, respiratory distress syndrome, and pulmonary embolus, were recorded. RESULTS: Thirteen patients developed pulmonary complications. Twelve of these had severe head injuries (GCS < or = 8). One had sustained an upper cervical spine fracture that resulted in quadriplegia. Statistical analysis revealed GCS, GCS < or = 8, ISS, and head and neck AIS to be significant predictors of pulmonary complications. Early stabilization of femur fractures had no apparent effect on the pulmonary complication rate. CONCLUSIONS: Pulmonary complications are rare in pediatric femur fracture patients. Patients with severe head injuries (GCS < or = 8) or cervical spinal cord injuries are at high risk for pulmonary complications. The timing of femur fracture stabilization does not appear to affect the prevalence of pulmonary complications in these patients.
Adolescent↗
Design and analysis of accelerated degradation tests for the stability of biological standards II. A flexible computer program for data analysis.
The accelerated degradation test is commonly used to predict the stability of a biological standard during long-term storage at low temperature. A flexible computer program is described which has been written to analyse degradation test results by the method of maximum likelihood. In addition to predicting the degradation rate at low temperature, the program furnishes estimates of statistical precision and it carried out a test of goodness of fit of the data to the assumed Arrhenius equation model.
Biological Products↗
Uncontrolled manifold analysis of single trials during multi-finger force production by persons with and without Down syndrome.
Recently, the framework of the uncontrolled manifold (UCM) hypothesis has been used to study multi-finger synergies based on analysis of motor variability across large sets of trials. We introduce a similar method of analysis, which can be applied to single trials, and hence may be more relevant to studies of atypical populations. In one experiment, results of across-trials and single-trial UCM analysis were compared for control participants who performed accurate ramp force production trials by pressing with four fingers of the hand. Both types of analysis revealed selective stabilization of total force by co-variations of individual finger forces. The stabilization was more pronounced at higher forces. When the participants purposefully varied the relative involvement of fingers during the ramp, significantly higher UCM effects were observed. However, high-pass filtering of the data at 4 Hz made these results similar to those observed in trials with natural patterns of force production. These observations allow assessment of the contribution of processes at two levels of a hypothetical hierarchical control system to the stabilization of total force. We also applied the single-trial UCM method to re-analyze previously published data from another experiment to study the motor variability in a group of persons with Down syndrome (DS) because these persons have difficulty in motor planning and timing as well as in force stabilization. Results of single-trial UCM analysis demonstrated force stabilization in these persons. The degree of force stabilization improved significantly after three days of practice. The analysis also showed that the total pronation/supination moment generated by the four fingers with respect to the midpoint was stabilized. The degree of moment stabilization did not change with practice. We conclude that the single-trial method of UCM analysis allows the analysis of hypotheses about stabilization of different performance variables by alleged multi-finger synergies in both typical individuals and individuals with DS.
Adolescent↗
Role of the C-terminal tail on the quaternary structure of aldehyde dehydrogenases.
To assess the importance of the C-terminal tail in the structure of aldehyde dehydrogenases (ALDH), mutants of tetrameric ALDH1 were generated by adding a tail of 5 amino acids (ALDH1-5aa) or the tail from the class 3 enzyme. A mutant of dimeric ALDH3 was made, where 17 amino acids from the C-terminus were deleted to generate ALDH3DeltaTail. The expression and solubility of the ALDH1 mutants was slightly lower than the wild type. Expression of ALDH3DeltaTail mutant was similar to wild type, but the solubility was only about 30%. The activity of ALDH1-5aa mutant was 30%, while ALDH1-H3Tail mutant was 60% active, compared to the wild type. The activity of the class 3 mutant was similar to the activity of the parent ALDH3 enzyme. Analysis of stability against temperature demonstrated that ALDH1-5aa was more stable than ALDH1 wild type, while the ALDH1-H3Tail mutant was considerably less stable than ALDH1, showing a stability similar to ALDH3. However, native gel and size exclusion analysis, showed no changes in the oligomerization state of these mutants. ALDH3DeltaTail mutant was more stable than wild type; the stability against temperature was similar to ALDH1. The ALDH3DeltaTail mutant showed an elution similar to that of ALDH1 from the size exclusion column, indicating that it was possibly a tetramer. These results show that the tail in ALDH3, is involved in the determination of the quaternary structure of ALDH3, but has no effect on the ALDH1 enzyme; the absence of the C-terminal tail is not the only factor participating in holding the dimers together. Thus, the interaction between single residues, or interactions with the N-terminal region might be more important for maintaining stable tetramers.
Aldehyde Dehydrogenase↗
A thermogravimetric analysis of non-polymeric pharmaceutical plasticizers: kinetic analysis, method validation, and thermal stability evaluation.
Four non-polymeric plasticizers, propylene glycol, diethyl phthalate, triacetin, and glycerin have been subjected to rising temperature thermogravimetry for kinetic analysis and vaporization-based thermal stability evaluation. Since volatile loss of a substance is a function of its vapor pressure, the thermal stability of these plasticizers has been analyzed by generating vapor pressure curves using the Antoine and Langmuir equations. Unknown Antoine constants for the sample compounds, triacetin and glycerin have been derived by subjecting the vapor pressure curves to nonlinear regression. For the first time, the entire process of obtaining the unknown Antoine constants through thermogravimetry has been validated by developing an approach called the 'double reference method.' Based on this method, it has been possible to show that this technique is accurate even for structurally diverse compounds. Kinetic analysis on the volatilization of compounds revealed a predominant zero order process. The activation energy values for vaporization of propylene glycol, diethyl phthalate, triacetin, and glycerin, as deduced from the Arrhenius plots, have been determined to be 55.80, 66.45, 65.12, and 67.54 kJ/mol, respectively. The enthalpies of vaporization of the compounds have been determined from the Clausius-Clapeyron plots. Rising temperature thermogravimetry coupled with nonlinear regression analysis has been shown to be an effective and rapid technique for accurately predicting the vapor pressure behavior and thermal stability evaluation of volatile compounds.
Chemistry, Pharmaceutical↗
Analytical strategy for detecting doping agents in hair.
Lists of banned classes of doping agents are released by the International Olympic Committee, adopted by other sports authorities and updated regularly, including the substance classes stimulants, narcotics, diuretics, anabolic agents, peptide hormones, beta-blockers etc. There are different classes of restriction: anabolic and masking agents (anabolic steroids, diuretics etc.) are always banned for athletes regardless of their topical activity (training or competition) several substances are permitted with certain restrictions (caffeine below a cut-off value, or inhalation of some beta 2 agonists) beta-blockers are prohibited in competitions of certain sports disciplines the majority of the substances (stimulants, narcotics etc.) is prohibited during competitions, so that they do not have to be analysed in out-of-competition samples. A differentiation between training and competition period is impossible by means of hair analysis due to the uncertainty of (especially short-term) kinetic considerations related to hair growth. Therefore, the analytical identification of doping relevant substances in hair is not always a sufficient criterion for a doping offence and the identification of stimulants, beta-blockers etc. in hair would be entirely irrelevant. The most interesting target substances are certainly the anabolic agents, because their desired action (enhanced muscle strength) lasts longer than the excretion, leading to sophisticated procedures to circumvent positive analytical results in competition control. Besides the analysis of out-of-competition control samples, the long term detection of steroids in hair could provide complementary information. An analytical approach to the identification of exogenous steroids in hair requires consideration of the presence of many other steroids in the hair matrix interfering the analysis at trace levels, and of a limited chemical stability. The analysis of endogenous steroids in hair appears to be even more complicated, because the possibility of many biotransformation reactions from (into) other precursors (metabolites) has to be taken into account. Precursor substances of anabolic steroids (especially esters as application forms) are very promising analytical targets of hair analysis, because they can only be detected after an exogenous intake. The quantitative evaluation of active parent compounds like testosterone (which is actively involved in physiological processes of hair growth) in hair is still controversial. Clinical applications under reproducible conditions can be useful, but the biovariability of these parameters will probably prevent the definition of acceptable cut-off levels as a criterion of abuse.
Adrenergic beta-Antagonists↗
Stability of femoral neck fractures. A postoperative roentgen stereophotogrammetric analysis.
Using roentgen stereophotogrammetric analysis, the postoperative stability of femoral neck fractures was measured in 16 patients. During the first day after internal fixation, before weight bearing, the center of the femoral head moved on an average 1.5 mm (total translation) in six undisplaced fractures and 3.7 mm in 10 displaced fractures, which was about one third of the fracture movement during the first postoperative month. Three undisplaced fractures displayed a rotatory instability, mainly after weight bearing had begun. Five of the displaced fractures showed maximal rotatory displacement during the first postoperative day. The recorded fracture movements before weight bearing may question the rationale of peroperative mechanical compression.
Aged↗
[Determination of trace elements in pure metal by optical emission spectrometry].
The important factor for trace concentration element analysis by optical emission spectrometry is detection limit, RSD, stability. Through study on analytical parameters of trace element in pure metal, it is found that the detection limit of element mainly depends on the choose analytical line and discharge type but bears no relation to reference. RSD and stability of analysis depend on analytical line pair(analytical line/reference line) and discharge type. The best analytical parameter will be selected to make quick and accurate analysis with this principle.
English Abstract↗
The determinants of stability in the human prion protein: insights into folding and misfolding from the analysis of the change in the stabilization energy distribution in different conditions.
The dynamic evolution of the PrP(C) from its NMR-derived conformation to a beta-sheet-rich, aggregation-prone conformation is studied through all-atom, explicit solvent molecular dynamics in different temperature and pH conditions. The trajectories are analyzed by means of a recently introduced energy decomposition approach aimed at identifying the key residues for the stabilization and folding of the protein. It is shown that under native conditions the stabilization energy is concentrated in regions of the helices H1 and H3, whereas under misfolding conditions (low pH, high temperature, or mutations in selected sites) it is spread out over helix H2. Misfolding appears to be a rearrangement of the chain that disrupts most of the native secondary structure of the protein, producing some beta-rich conformations with an energy distribution similar to that of the native state.
Computer Simulation↗
The stability of the hippocampal slice preparation: an electrophysiological and ultrastructural analysis.
The viability and stability of the in vitro rat hippocampal slice preparation were assessed using electrophysiological and electron microscopical means. Slices exhibited lifetimes of 6-19 h. Correlation between the duration of electrical activity and changes in ultrastructure of these slices was found. Possible reasons for the wide variability in lifetime of the hippocampal slice are suggested.
Animals↗
Stability of radioiodinated monoclonal antibodies: in vitro storage and plasma analysis.
The in vitro stability and immunointegrity of four radioiodinated monoclonal antibodies was evaluated in various storage conditions and also in plasma samples. The monoclonal antibodies studied included T101, B72.3, Lym1, and 16.88. Stabilities of typical monoclonal antibody therapy solutions, with radioactivities ranging from 2220 to 3700 MBq (60-100 mCi) were assessed using conventional instant thin layer chromatography and size exclusion high performance liquid chromatography. Radioimmunoreactivity was assessed using a live cell attenuated cell, or mucin-linked bead assay. Results of the study demonstrated that therapy solutions were stable to degradation, if properly stored in 5 or 10% human serum albumin at 4 degrees C for the duration of the study (5 days). Minor losses in immunoreactivity were also measured in stabilized therapy solutions. When incubated in plasma samples, radioiodinated monoclonal antibodies generally remained stable for the duration of the study (3 days). However, significant decreases in immunoreactivity were measured for specific radioiodinated monoclonal antibody preparations.
Antibodies, Monoclonal↗
[Shelf-life estimation of pharmaceutical products by matrixing].
The shelf-life estimates of pharmaceutical products obtained by matrixing are compared with those obtained by ordinary analysis, using stability data generated by the Monte Carlo method. The effect of the variation in stability due to different packaging and formulations on the shelf-life estimates is described. Analysis of variance is proposed for the evaluation of shelf-life estimates obtained by matrixing. The relationship between the power of the test and the significance level is discussed as well as the effect of assay error on the power of test.
Analysis of Variance↗
Stability of lactate dehydrogenases. I. Chemical modification of lysines.
The lysine residues of lactate dehydrogenase (L-lactate: NAD+ oxidoreductase, EC 1.1.1.27) can be amidinated by methyl-4-hydroxy-3-nitrobenzimidate to introduce nitrophenolate anions. This modification results in lowered thermal stability, as does acetylation. The conversion of these groups into uncharged aminophenol groups without further modification of the enzyme itself stabilizes the enzymes from pig heart and muscle and from chicken muscle, as does acetamidination, but the unusually stable enzyme from chicken heart reverts only to the stability of the native form. The results allow for the following conclusions. Destabilization is brought about at many points at the surface of lactate dehydrogenases by neutralization of positive charges. Stabilization, in contrast, is concluded to be due to modification of one lysine at position 241 of the sequence. This lysine must have been changed to arginine during the evolution of heart-type lactate dehydrogenases in going from lower to higher reptiles. This exchange has been conserved in the enzymes from the hearts of birds and therefore the enzyme from chicken heart is very stable and cannot further be stabilized by modification of lysines. From X-ray structure analysis, the stabilization by exchange of Arg for Lys at position 241 or by amidination is explained by the formation of additional ion pairs with aspartic acid57 of the Q-related subunits.
Animals↗