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At least 1,063 records · Page 59Linked to original sources
PubMed1975

Biomechanical analysis of structural stability of internal fixation in fractures of the thoracolumbar spine.

Three different methods of internal fixation for the flexion-rotation thoracolumbar spinal fractures were tested biomechanically in a cadaver model for strength, mode of failure and ease of application. The compression rod system was clearly superior in strength and rotational stability to the spring device, but it was more difficult to apply than springs. The distraction rod system exhibited an intermediate level of strength with adequate rotational stability. Technically, the method is exacting and requires a clear understanding of its principle of 3 point fixation.

Biomechanical Phenomena↗
PubMed2004

Pharmacokinetics, stability, and retrospective analysis of use of an oral gel formulation of the bovine injectable enrofloxacin in horses.

In many cases of equine infectious disease, long-term administration of antimicrobial drugs is required. Oral agents are preferred because of the relative ease of administration compared with other routes. Enrofloxacin has been shown to be effective against a variety of equine pathogens, but oral administration of this drug has proved difficult in horses. An oral gel formulation made from the injectable cattle product produces blood levels sufficient to resolve infections caused by a variety of common equine pathogens.

Absorption↗
PubMed1989

Analysis of the stability of alanine aminotransferase (ALT) levels in donor samples.

This study was designed to 1) analyze the stability of serum alanine aminotransferase (ALT) activity in nonsepanted donor samples stored at room temperature (RT) over 72 hours and 2) compare ALT levels of paired samples stored at RT and 4 degrees C over the same time period. The study showed that mean ALT activities for samples stored at RT increased at all assay times and that those stored at 4 degrees C decreased (0.54 IU/L over 72 hours). Although the mean increase in activity of the RT samples over 12 hours (1.45 IU/L) was statistically significant, it was of little practical significance. For example, based on the frequency distribution of the 311 RT samples from this study, and using a cut-off value of 69 IU/L, only one unit of blood would have been eliminated based on the difference between time zero and 12 hours. It was concluded that RT would be the storage of choice for 72 hours, since the tendency of ALT levels to decrease during storage at 4 degrees C could make possible the inclusion of borderline donor units in the blood supply.

Journal Article↗
PubMed1990

The establishment of rat hybridoma cell lines secreting McAb against strains of potato virus Y and analysis of its stability.

The rat splenocytes immunized with potato virus Y (PVYn) and ratmyeloma (IR983) were fused by PEG (M. W.1450). Three kinds of stable hybridoma cell lines secreting specific monoclonal antibodies (McAbs) were derived. One kind of the cell lines producing McAbs reacts to PVYn specifically. Another reacts to PVYo specifically. The third one reacts to both of the two strains. Tested by the methods of sandwich-ELISA and indirect-ELISA, all kinds of McAbs did not react to seven plant viruses: tobacco mosaic (TMV), cucumber mosaic (CMV), tobacco tech (TEV), alfalfa mosaic (AMV), turnip mosaic (TuMV), potato leaf roll (PLRV), potato virus X (PVX). The biological properties of the hybridoma cell lines and the McAbs were tested.

Animals↗
PubMed1989

Molecular analysis of clonal stability and longevity in B cell memory.

We used the antiphosphocholine response induced by Proteus morganii and an adoptive transfer protocol to study the contribution of individual clones to B cell memory. Spleen cells from donor mice immunized with P. morganii were injected into irradiated hosts. These recipients were then immunized and their spleen cells fused 12 to 14 wk thereafter. The sequences of hybridoma VH and VL were obtained and DNA rearrangements at both V region loci were studied to ascertain clonal relationships. In all three adoptive transfer experiments, each mouse of a pair receiving cells from the same donor contained hybridomas which were clonally related to each other. In two of these experiments paired recipients possessed cells that had identically mutated V genes. These results lead us to conclude that once a B cell clone(s) dominates a response, progeny of that clone form the memory cell population for many months. Moreover, stability appears to be generated in some memory B cells through inactivation of the hypermutation mechanism.

Amino Acid Sequence↗
PubMed1987

Deficiency of the C3b/C4b receptor (CR1) of erythrocytes in systemic lupus erythematosus: analysis of the stability of the defect and of a restriction fragment length polymorphism of the CR1 gene.

The role of genetic factors in controlling CR1 quantitative expression on erythrocytes (E) of patients with systemic lupus erythematosus (SLE) was reexamined by determining the temporal stability of CR1 numbers and the frequency of a CR1 genomic restriction fragment length polymorphism (RFLP). The mean number of binding sites/(E) for Yz-1 monoclonal anti-CR1 correlated with the number of sites for polyclonal anti-CR1 that had been determined 2 to 4 yr previously in 18 normal persons (p less than 0.001), 18 patients (p less than 0.001), and 28 relatives (p less than 0.001), indicating that CR1 sites/E was a stable characteristic in all three groups. The mean number of Yz-1 sites/E was 281 +/- 34 (+/- SEM) in 28 probands with SLE and 457 +/- 21 in 93 relatives, both determinations being less than that for 100 normal persons, 553 +/- 21 (p less than 0.002). Thirty-six patients and 51 normal individuals were also assessed for the presence of the 7.4 kb and 6.9 kb HindIII CR1 allelic restriction fragments that correlate with high and low expression, respectively, of CR1 on E. The distribution of patients differed from normal (p less than 0.05), with a smaller proportion being homozygous for the 7.4 kb allele. In addition, the mean numbers of Yz-1 sites/E for patients and relatives who were homozygous (p less than 0.02) and heterozygous (p less than 0.05) for the 7.4 kb allele were significantly lower than those for normal persons matched for the HindIII RFLP, suggesting the existence of additional heritable factors that decrease CR1 expression. The stability over time of the CR1 deficiency among patients, the finding of decreased CR1 number among an expanded group of relatives, the altered frequency among patients of CR1 alleles defined by the HindIII RFLP, and the decreased expression of CR1 on E among patients and relatives compared with normal individuals having the same HindIII RFLP indicate a role for genetic factors in CR1 deficiency in SLE.

Alleles↗
PubMed1986

Statistical analysis of the stability of the standard curve for some Syva EMIT assays.

Derivation of standard curves for the EMIT therapeutic drug monitoring system involves several mathematical algorithms, all of which can be rewritten in the form of a linear equation y = mx + b. We examined the stability of the standard curve in terms of slope and y-intercept for three drug assays (procainamide, gentamicin, and carbamazepine) by generating calibration curves intermittently for periods as long as 90 days. Controls at three concentrations were assayed after each calibration to validate the standard curves. On the basis of 98% confidence intervals, the slopes of standard curves for procainamide, gentamicin, and carbamazepine were stable for 89, 80, and 57 days, respectively. Control values generated from standard-curve manipulations (adjustments to the y-intercept) indicated consistent accuracy and precision throughout the entire study, as compared with control values determined after each calibration. The increased utility of the standard curve and reagents suggests that full recalibration on a regular basis is not always necessary.

Carbamazepine↗
PubMedDate not supplied

[Analysis of the stability of rabbit visual cortex neuron spike responses to light flashes].

The stability of neuronal responses in the rabbit visual cortex to diffuse photic flashes presented in series with sufficiently long time intervals between them was studied in acute experiments. Three types of neuronal responses with different degree of stability were singled out. The stability was judged by the mean coefficient of correlation between post-stimulus histograms of spike activity. Negative correlations were found between the mean correlation coefficient and mean square deviations of latencies of primary and secondary activation and the pause in impulse activity in neuronal responses to a photic flash. Positive correlations between primary activation latencies and mean square deviations of other response parameters suggest a greater stability of responses with a short latency.

Action Potentials↗
PubMedDate not supplied

[Comparative analysis of the stability of cardiovascular system functions in immobilized rats of different strains].

The dynamics of arterial pressure and heart rate was studied in rats of different genetic lines (non-linear, Wistar, Way and August) during immobilization emotional stress. Different lines were characterised by different stability and ability of adaptation to emotional stress. Prognostic criteria were specified that enable to foresee at an early stage of emotional stress the disturbances of cardio-vascular control. The conclusion is made that resistancy against cardio-vascular disturbances during emotional stress is of genetic nature as well as may be due to characteristics of individual growth.

Animals↗
PubMed1984

The Pennsylvania Infant and Family Development Project, II: The development of reciprocal interaction in the mother-infant dyad.

In order to assess stability and change in mother-infant interaction, 74 mother-infant dyads were observed at home under naturalistic conditions when infants were 1, 3, and 9 months. Both conceptually and empirically guided data-reduction procedures indicated that 4 summary constructs underlie 15 behavioral categories coded: reciprocal interaction, noninvolvement, distress, and basic care. Mean levels of reciprocal interaction remained unchanged over time, with individual differences being stable. Mean levels of noninvolvement increased from 1 to 3 months only, and remained stable across all time periods, while mean levels of distress and basic care declined linearly across the 9-month periods, with individual dyads displaying little stability. A final analysis assessed stability and change in the 9 component variables comprising the reciprocal interaction construct. Significant change was discerned with respect to several of these components, as well as a good deal of instability. These findings led to the conclusion that, in the face of sameness in mother-infant interaction across the first 9 months, there is also much change.

Adult↗
PubMed1981

[Analysis of the stability and local cooperativity of DNA: proposal of a molecular mechanism for the initiation of the transcription of gene A3 of bacteriophage T7 by the RNA polymerase from E. coli].

RNA polymerase (RNAP) complexed to the A3 promoter of bacteriophage T7 is known to unwind a DNA segment located downstream of the Pribnow box. This finding can be accounted for if it is assumed that the subunit sigma of RNAP unstabilizes three GC base pairs located just upstream of the transcription start. As a consequence, the rate of promoter utilisation might be related to the relative stability of the DNA between the "Pribnow box" and the transcription start.

Base Composition↗
PubMed1983

[Analysis and the stability of codeine phosphate. 2: Stability of aqueous codeine phosphate solutions].

The degradation velocity of aqueous codeine phosphate solutions is of first order. The formation of the degradation products (isomerization products) depends upon temperature, light and pH value. At pH = 3.5, codeine phosphate solutions are relatively stable. Atmospheric oxygen exerts no effect. Of the complexing agents and antioxidants tested, only citric acid and thiourea seem to be capable of reducing the rate of degradation. Besides glass ampoules, plastic containers of low-density polyethylene proved to be suited for codeine phosphate solutions.

Antioxidants↗
PubMed1983

[Analysis of the stability of the intermediate fibrin polymers formed in a fibrinogen-thrombin system].

Intermediate fibrin polymers formed from fibrinogen at low thrombin concentrations under physiological conditions are studied for their stability. Smith's statement that intermediate fibrin oligomers are inert molecules whose further self-assembly is possible only under additional thrombin activation was not supported. It is shown that the intermediate fibrin polymer stability at pH 7.4 is not high because of a strong tendency to aggregation and the higher molecular weight of the polymer the less its stability. The polymer stability in solution increases with pH. Stability of soluble fibrin complexes in solution depends on their size, defined by environmental conditions and on the quantity of fibrinogen present.

Animals↗