[Conservative treatment of idiopathic scoliosis].
Explore the source record for details and available documents.
Adolescent↗
Biomedical subjects
R Bauer
Publications and source records attributed to R Bauer.
Comparison between single-screw and triangulated, double-screw fixation in anterior spine surgery. A biomechanical test.
STUDY DESIGN: The advantage to fixation strength of triangulated, double-screw fixation compared with that of single-screw instrumentation in anterior spine surgery was evaluated by in vitro testing. OBJECTIVES: To compare the fixation strength of single-screw instrumentation with ventral derotation spondylodesis screws with the fixation strength of triangulated, double-screw instrumentation with Cotrel-Dubousset-Hopf screws. Resistance against pull-out load and against load perpendicular to the axis of the screws was evaluated. To avoid the bias caused by different screw design, the pull-out strength of single screws of both devices was compared first. SUMMARY OF BACKGROUND DATA: To the authors' knowledge, no study comparing anterior single with triangulated screws has been published. METHODS: A pull-out test was performed when one vertebra in each spine specimen was instrumented with a ventral derotation spondylodesis screw, one with an isolated Cotrel-Dubousset-Hopf screws, and one with two triangulated, Cotrel-Dubousset-Hopf screws linked by a Cotrel-Dubousset-Hopf block. Load perpendicular to the axis of the screw was applied on the bone-device interface after instrumentation of further specimens with ventral derotation spondylodesis and triangulated, Cotrel-Dubousset-Hopf devices. RESULTS: Use of isolated Cotrel-Dubousset-Hopf screws compared with ventral derotation spondylodesis screws showed no significant differences in pull-out strength. The use of triangulated, double-screw fixation with Cotrel-Dubousset-Hopf screws led to a significant 79% increase in resistance against pull-out and a 73% increase in resistance against load perpendicular to the screw axis compared with the resistance produced using ventral derotation spondylodesis single-screw instrumentation. CONCLUSION: In anterior surgery, fixation of the vertebra-device interface can be improved considerably by application of two triangulated screws.
Aged↗
The protein conformation of Cd-substituted horse liver alcohol dehydrogenase and its metal-site coordination geometry in binary and ternary inhibitor complexes.
The coordination geometry of the metal at the active site in Cd-substituted horse liver alcohol dehydrogenase (LADH) has been investigated for the binary complexes of LADH with imidazole, isobutyramide, decanoic acid and Cl-, and for the ternary complexes of LADH with NADH and imidazole, NADH and isobutyramide, NAD+ and decanoic acid and NAD+ and Cl-, by using the method of perturbed angular correlation of gamma-rays (PAC). The spectral results are consistent with a flexible structure around the metal for the binary complexes with inhibitors. For ternary complexes, however, a rigid structure is observed. An exception is the ternary complex between LADH, NADH and imidazole, in which the metal site is still flexible. Comparing with available structures determined by X-ray crystallography, we found a correlation between open structures and flexible metal sites, and between closed structures and rigid metal sites. This indicates that the PAC technique can be applied to distinguish the two conformations in solution. The spectral parameters, omega(o) and eta, of the experiments, except for the complexes with imidazole, fall into two groups: one with low omega(o) and one with high omega(o) (eta is relatively constant in all experiments). In this work it is clarified that the low omega(o) values are connected with the presence of a negatively charged solvent ligand. Using an angular-overlap approach to interpret the results, the low omega(o) values are found to be compatible with a coordination geometry where the S-Cd-S (Cys174 and Cys46 coordinate to the metal) angle is about 110 degrees as suggested in [Hemmingsen, L., Bauer, R., Danielsen, E., Bjerrum. M. J., Zeppezauer, M., Adolph, H. W., Formicka, G. & Cedergren-Zeppezauer, E. (1995) Biochemistry 34, 7145-7153], whereas high omega(o) values are compatible with an S-Cd-S angle of 130 degrees. The presence of a negatively charged metal ligand, therefore, might trigger the movement of the sulfur of Cys174. As it is believed that alcohols coordinate to the metal as alcoholate ions this could be important for catalysis.
Alcohol Dehydrogenase↗
Relations between parameters of spectral power densities and deterministic chaos of heart-rate variability.
To evaluate whether or not heart-rate variations (HRV) have both periodic and deterministic-chaotic properties in conscious and anaesthetized states, HRV of 9 rabbits were analysed by power spectral analysis and methods of deterministic chaos. In order to correlate these properties with the physiological structure of HRV, cholinergic and beta-adrenergic blockades and medullar transections were done. A predominant deterministic-chaotic structure of HRV with high fractal correlation dimension (CD) during conscious state changes to a more periodic structure and lower CD during general anaesthesia. The main periodic and deterministic-chaotic components of HRV are vagally mediated because of their strong reduction by cholinergic blockade, but not by beta-adrenergic blockade or medullar transection.
Animals↗
Axial rotation measurement of scoliotic vertebrae by means of computed tomography scans.
STUDY DESIGN: This study evaluated the preconditions for exact axial rotation measurement and the possibility for other parameters to measure axial rotation and mechanical torsion. OBJECTIVES: Quality criteria for axial rotation measurement in computed tomography scans are not established yet. Criteria should be found to improve axial rotation measurement. SUMMARY OF BACKGROUND DATA: To the authors' knowledge, no systematic analysis of the errors of axial rotation measurement based on computed tomography scans has been performed. METHODS: Axial rotation was measured in 259 computed tomography scans of 11 cadaveric vertebrae from scoliotic specimens. The sagittal axial rotation measurement angle of Aaro and Dahlborn and a new rotation parameter were measured with a pencil and ruler. Five landmarks were digitized and consequently five axial rotation parameters were computed. The influence of insufficient visualization of bony landmarks, mechanical torsion of the vertebra itself, and oblique position of the vertebra was evaluated. RESULTS: Accuracy is considerably improved in central computed tomography scans (same distance to the top and bottom of the vertebral body) due to good visualization of landmarks and reduction of effects of mechanical torsion. The oblique vertebral position causes more errors. One mechanical torsion parameter with sufficient reliability is identified. CONCLUSION: The sagittal axial rotation measurement method of Aaro and Dahlborn is superior to other techniques of measurement. It can be improved considerably if computed tomography scans fulfill certain quality criteria.
Anthropometry↗
Imaging of dopamine receptors with [123I]iodobenzamide single-photon emission-computed tomography in neuroleptic malignant syndrome.
With the tracer [123I]iodobenzamide ([123I]-IBZM), it is possible to image dopamine receptor occupancy with single-photon emission-computed tomography (SPECT). We report follow-up examinations with IBZM-SPECT in neuroleptic malignant syndrome (NMS) to display D2-receptor availability in the acute phase and during the course of remission. A 27-year-old man was admitted with severe akinesia, rigor, tachycardia, fever, and elevated creatine phosphokinase level (CK) after neuroleptic medication. NMS was diagnosed, and treatment was started with dantrolene, amantadine, and dopamine agonists. IBZM-SPECT examination was performed on days 6, 34, 90, 107, 131, and 201. In the acute state of NMS, there was no binding of IBZM to D2-receptors. SPECT reached almost normal values on day 131, but clinical examination still showed a mild parkinsonian syndrome. With SPECT, the D2-receptor occupancy in NMS could be successfully shown in correlation with extrapyramidal signs. IBZM-SPECT may therefore serve to monitor D2-receptor occupancy in patients at risk for NMS.
Adult↗
Effects of Cerebrolysin on cytoskeletal proteins after focal ischemia in rats.
Explore the source record for details and available documents.
Amino Acids↗
Influence of severe hemodilution on brain function and brain oxidative metabolism in the cat.
OBJECTIVE: It has been established that during constant pressure arterio-venous bypass perfusion, brain metabolism gradually deteriorates in parallel with the declining hematocrit. However, whether this is due to a disturbance of flow regulation or to the decline in the oxygen-carrying capacity of the blood has not been documented. Therefore, intact animals were submitted to severe hemodilution to determine the threshold for the beginning of functional and biochemical impairment of the brain. METHODS: Six anesthetized and paralyzed adult mongrel cats were submitted to gradual isovolemic hemodilution by stepwise exchange of blood with Ringer lactate/dextran (1 : 1) solution. Exchange of 80 ml/kg body weight resulted in a final hematocrit level ranging from 6.1% to 11%. RESULTS: Cerebral blood flow gradually increased during hemodilution, with a sharp rise to eight times the prehemodilution value when the hematocrit fell below 10%. The calculated oxygen delivery to the brain remained relatively unchanged. Hemodilution did not cause suppression of spontaneous ECoG or somatically evoked primary cortical potentials, even at the lowest hematocrit value of 6.1%. Brain tissue ATP and phosphocreatine content were largely maintained, although tissue lactate content was elevated (9.54 +/- 5.99 micromol/g). CONCLUSIONS: The hemodynamically unimpaired healthy mammal is able to support a substantial degree of hemodilution without major functional or biochemical disturbance to the brain. The previously observed disturbances during prolonged bypass perfusion are, therefore, most probably due to the associated abnormalities of flow regulation.
Adenosine Triphosphate↗
Nevadensin glycosides from Lysionotus pauciflorus.
Two new flavone glucosides, nevadensin 5-O-beta-D-glucoside and nevadensin 5-O-beta-D-glucosyl(1-->6)beta-D-glucoside, have been isolated from the aerial parts of Lysionotus pauciflorus. The structures have been determined by means of UV, mass spectral and one- and two-dimensional 1H and 13C NMR techniques.
Animals↗
The role of magnetic resonance imaging and scintigraphy in the diagnosis of pathologic changes of the mandible after radiation therapy.
A prospective study of 85 patients with oral cancer, treated with high-dose radiation therapy, was performed to assess the value of magnetic resonance imaging (MRI) and scintigraphy for diagnosis of pathologic changes in the mandible. During postradiotherapeutic monitoring, radiation osteomyelitis occurred in 12 cases, tumor recurrences infiltrating the mandible in five cases, and progressive periodontal disease in nine cases. MRI permitted early diagnosis of radiation osteomyelitis in 11 out of 12 cases; only two cases were false positive. In scintigraphy with 99mTc-HDP, all alterations of the mandible, such as osteoradionecrosis, tumor infiltration, and periodontitis, showed a high uptake, resulting in a sensitivity of up to 100%, but a low specificity of 57%. Scintigraphy permitted assessment of the extension and location of the lesions. Both methods were superior to conventional radiography and clinical examination and should be integrated into a comprehensive follow-up program after radiation therapy.
Adult↗
Colored microsphere technique as a new method for quantitative-multiple estimation of regional hepatic and portal blood flow.
A new method for multiple, quantitative estimation of regional splanchnic blood flow is presented which overcomes all the limitations of the radionuclide microsphere technique. By direct comparison of two methods, i.e., simultaneous blood flow measurement with radionuclide-labeled and colored microspheres, it was shown that the quality of flow measure was quite similar. Simultaneous measurement using paired radionuclide-labeled microspheres yielded an excellent correlation between both values of r = 0.997, a variability of 4.58 +/- 3.84% and a SEE-value of 0.167 ml/g/min. The colored microsphere technique produced corresponding values with r = 0.998, a variability of 5.94 +/- 7.80% and a SEE-value of 0.212 ml/g/min (n.s.). This is also shown for five different abdominal organs and tissues with quite different flow rates under normal physiological conditions. Thus, the colored microsphere technique is a suitable experimental method for making multiple and quantitative measures of the nutritive blood flow through splanchnic organs and tissues and yields values of arterial blood inflow into the liver and into the circulatory bed which is drained by the portal vein.
Animals↗
Characterization of autoantibodies to natural killer cells in HIV-infected patients.
Natural killer (NK) cells in HIV-infected patients have a reduced ability to generate non-MHC restricted cytotoxicity to a variety of target cells. The authors investigated antibodies to NK cells in HIV-infected patients and evaluated effects of these antibodies to NK cell numbers and function. Antibodies to NK cells were determined in 160 HIV-infected patients and 35 healthy controls. Flow cytometric whole blood methods were developed to detect antibodies to NK cells. Antibodies to asialo-GM1 were detected by TLC immunostaining. The presence of antibodies to NK cells was demonstrated in plasma of about one-third (54/160) of HIV-infected patients but rarely in controls (2/35). Auto-antibodies bound to NK cells in vivo and were detected by a strong increase of surface immunoglobulin (Ig) on NK cells of HIV-infected patients. Anti-NK cell antibodies were warmreactive antibodies rather of IgG than of IgM phenotype. The prevalence of specific antibodies to asialo-GM1 was low (12.5%). Numbers of circulating NK cells did not differ significantly between antibody positive (99.5/microliters) and antibody negative (141/microliters) patients (P = 0.3). However, pre-incubation of healthy donors' NK cells with autoantibody positive plasma significantly inhibited cytotoxicity to K562 leukaemic cells (P = 0.002). Autoantibodies to NK cells in HIV-infected patients are present in the plasma of one-third of HIV-infected patients and are bound to NK cells in vivo. There is evidence that these autoantibodies can induce NK cell defects similar to those seen in vivo.
Antibodies, Anti-Idiotypic↗
Small-angle neutron scattering from multilamellar lipid bilayers: Theory, model, and experiment.
Explore the source record for details and available documents.
Journal Article↗
Vibroacoustic stimulation with a complex signal: effect on behavioral state in fetal sheep.
An ideal vibroacoustic stimulus for testing fetal reactivity has yet to be developed. In the present study in fetal sheep we tested the effect on behavioral state of an amplitude and frequency-modulated signal produced at the abdominal surface of the ewe. The stimulus was presented during periods of fetal non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. Evaluation of behavioral state was accomplished by visual observation of strip-chart recordings. Assessed in this manner, vibroacoustic stimulation during NREM sleep consistently resulted in a change to an indeterminate state. However, stimulation during REM sleep failed to have an effect. Additional evaluation applying spectral analysis to the fetal electrocorticogram during stimulation in NREM sleep revealed a marked decrease in delta band power from 100 to 27 +/- 5% and in theta band power from 100 to 40 +/- 4% resulting in a decrease in total power from 100 to 35 +/- 4% (p < 0.05). Stimulation during REM sleep revealed a significant increase in beta band power from 100 to 123 +/- 14%. Vibroacoustic stimulation in both NREM and REM sleep led to an increase in spectral edge frequency, implying central arousal.
Acoustic Stimulation↗
AIDS information on the Internet (Part 2): Critical Path Internet services.
Explore the source record for details and available documents.
Acquired Immunodeficiency Syndrome↗
Early migration predicts late aseptic failure of hip sockets.
We report a prospective, stratified study of 60 PCA-cups and 60 RM-polyethylene cups which have been followed for a median time of 90 months, with annual radiography. The radiological migration of cups was measured by the computer-assisted EBRA method. A number of threshold migration rates from 1 mm in the first year to 1 mm in five years have been assessed and related to clinically determined revision rates. A total of 28 cups showed a total migration of 1 mm or more within the first two years; 13 of these cups have required revision and been exchanged. The survival curves of cups which had previously shown early migration were considerably different from those without early migration. For cups with a migration of less than 1 mm within the first two years the mean survival at 96 months was 0.96 +/- 0.02; for migrating cups, it was 0.63 +/- 0.11 (log-rank test, p=0.0001; chi-square value=39.4). Early migration is a good predictor for late loosening of hip sockets.
Aged↗
Characterization of complex heart rate dynamics and their pharmacological disorders by non-linear prediction and special data transformations.
OBJECTIVE: The aim of the presented method was the characterization of different complex heart rate dynamics in conscious rabbits as well as during general anaesthesia and vagal blockade. This was done by non-linear prediction of original measured and special surrogate data in the phase space. METHOD: The development of the prediction error in dependence on the prediction time interval was investigated in the phase space. Two kinds of surrogate data were produced and tested with regard to non-linearities and orientation in the phase space. Typical characteristics of prediction error development were shown for simulated uncorrelated stochastic, correlated stochastic, regular deterministic, and deterministic chaotic signals. These characteristics were used to evaluate the measured heart rate data in connection with tests of surrogate data. RESULTS: It could be shown that heart rate fluctuation cannot be described by one of these ideal models alone. Common consideration of all investigated prediction characteristics indicated chaos in the heart rate of conscious rabbits as well as during anaesthesia and vagal blockade, where non-linear correlated stochastic properties could not be excluded. The different amount of non-linearities and orientation was described quantitatively. CONCLUSIONS: Detailed analysis of prediction error development in the phase space, connected with tests for non-linearities and orientation, enabled a specific quantitative characterization of complex heart rate dynamics and their pharmacological disorders.
Anesthesia, General↗