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61.
After having reported preliminary results of soft system stabilization according to Graf in a series of 27 patients with degenerative disc disease of the lumbar spine in early 1995 the authors report long term clinical and radiological results of this patient series (n = 25). At a mean period of postoperative observation of 50 months excellent, good, satisfactory, moderate and poor results were obtained in 62, 9%, 11, 1% and 11, 1%, 7, 4% and 7, 4% of the patients, respectively. The well-known phenomenon of loss of disc height at the level of posterolateral fusion and instrumentation as well as overcharge of adjacent segments were not observed after soft system stabilization. Regional as well as global lumbar lordosis were maintained and, although statistically not significant, an increase of intervertebral distance was observed in adjacent segments in flexion of the lumbar spine. These phenomena might represent pressurization of instrumented as well as adjacent discs after the insertion of ligament prostheses. It is the impression of the authors, that the Graf technique leads to good surgical results in degenerative disc disease with destabilization of lumbar motion segment(s) if the following criteria are strictly respected: 1. No or only mild arthrotic changes of the facet joints 2. Preferably minor disc degeneration/only mild loss of intervertebral distance. 3. Well trained low back muscles and 4. A clear-cut, repeatedly demonstrated pain-relief on trial anaesthesia of the corresponding articular nerves and while wearing a probatory jacket.  相似文献   
62.
STUDY DESIGN: Morphological analysis was performed of the facet joint of the normal and spondylolytic lumbosacral spine in children and adolescents. OBJECTIVES: This study was performed to estimate the influence of spondylolysis on growth of the neural arch of the lumbosacral spine. SUMMARY OF BACKGROUND DATA: The development of the facet joint and its relation to spondylolysis have not been documented in the literature. METHODS: The dimension and orientation of the facet joint at L5/S were measured on radiographs and computed tomography scans from 144 boys without pars defects and 104 boys with pars defects. The latter group was further investigated according to the stage of pars defects. Patients in both groups were between 9 and 18 years of age. RESULTS: Growth of the facet joint in the sagittal and transverse directions and the increase of the transverse angle were remarkable up to approximately 13 years of age. Concavity of the facet joints also progressed in children of the same age. The growth of the facet joint in patients with spondylolysis was significantly retarded as the pars defects advanced from the progressive to the terminal stage. The joint surface was more coronal in orientation and flatter in shape compared with controls. CONCLUSIONS: The present results suggest that pars defects occurring in children disturb or retard the growth of the facet joint and that the morphological characteristics of the joint surfaces in patients with spondylolysis are the consequence of these defects.  相似文献   
63.
Balloon pulmonary valvuloplasty was performed in 3 infants with severe tetralogy of Fallot at days 24, 54 and 86 because of progressive hypoxemia. In two patients, the balloon catheter (4 cm long, 5-8 mm diameter) could not pass through the pulmonary valve. This necessitated a smaller balloon and required a two-step procedure. Initially, a coronary artery balloon (2 cm long, 3.5 mm diameter) was used. Following balloon valvuloplasty, arterial oxygen saturation increased from 63 to 83% in case 1, from 69 to 85% in case 2 and 63 to 86% in case 3. Immediate postvalvuloplasty right ventricular cineangiography revealed that the maximal opening diameter of the pulmonary valve leaflets increased from 1-2 mm to 3-4 mm in cases 1 and 3, and from 2-3 mm to 4-5 mm in case 2. No significant complications occurred. Echocardiographic follow-up data showed that the diameter of the right ventricular outflow tract and pulmonary arteries increased with age. The present results show that the pulmonary valvuloplasty is an effective procedure for relief of pulmonary valve stenosis in tetralogy of Fallot and to improve oxygenation and growth of the pulmonary arteries and right ventricular outflow tract without the need of an immediate aortopulmonary shunt.  相似文献   
64.
Shin Yubari coal (86.7% C) was mildly hydrogenated repeatedly at 340–385°C under an initial hydrogen pressure of 10 MPa for 1 h, using Adkins catalyst. The product was extracted with benzene at 200°C and the residue was again reacted. Finally, benzene solubles were extracted with n-hexane, and n-hexane insolubles were hydrogenated under similar conditions at 380°C; the product was then extracted with n-hexane. The yield of total n-hexane solubles was 52.5%. Acid and base were extracted with sulfuric acid and NaOH, and the neutral part (50.2%) was chromatographed using an alumina column with 2.5% water and separated into 12 fractions. UV and IR spectra, ultimate analysis and 1H-NMR spectra were obtained for each fraction and a structural analysis was carried out to obtain an image of each average structure. The aromatic ring numbers estimated from UV spectra and from structural analysis for each fractions agree well with each other; the average value was 3.2.  相似文献   
65.
Low-noise amplifiers for u.h.f. colour t.v. broadcasting translator use have been successfully developed by using 1 ?m gate GaAs m.e.s.f.e.t.s. The obtained performances revealed that a GaAs m.e.s.f.e.t. has low-noise and low intermodulation distortion characteristics, even in the 500?800 MHz frequency range, compared with a Si bipolar transistor.  相似文献   
66.
Rates of absorption of CO2 into water, a 0.2 mol/L NaOH solution and a 40 wt% glycerol solution with and without the interfacial turbulence caused by micro-stirrers, made of a magnetic material, were measured with use of a stirred vessel with known gas-liquid interfacial area. The effect of the interfacial turbulence on the rate of gas absorption was remarkable in the lower range of the bulk turbulence. The enhancement factors due to the interfacial turbulence were calculated with use of the age distribution function of the Danckwerts type and they agreed well with the experimental results.  相似文献   
67.
The sputtering process by an ion beam well collimated and highly accelerated provides a valuable means of high resolution shadowing, replication of a fine object by a combination of pre-shadowing and deposition as well as a preparation of supporting films. High resolution shadowing and films with grains smaller than 1 nm can be obtained by argon ion-sputtering targets of tungsten and tungsten/tantalum alloy. The resolution of carbon replicas pre-shadowed with tungsten/tantalum is determined from the radius of curvature of replicated magnesium oxide crystal corners.  相似文献   
68.
Using a semicontinuous culture method, in which operational parameters such as cell concentration and light intensity distribution were maintained almost constant, instability of the specific growth rate of Rhodobacter capsulatus B-100, a purple bacterium, was observed to be similar to that of R. capsulatus ST-410 when cultivated under high ratios of light intensity on the illuminated side to that of the transmitted light. Such instability was not observed in the cultivation of Chlorella vulgaris, a eukaryotic green alga, even at higher cell concentrations. Under the same conditions, the increase in only the ferrous concentration from 43 microM, the concentration in the original RCV medium, to 172 microM sustained a stable growth, whereas Fe(2+) was slightly consumed during the cultivation. Supplemental illumination with a fluorescent lamp on the transmitted side of a flat plate photobioreactor sustained a moderate level of stable growth, while a halogen lamp slightly affected the growth stability. Our results showed that an increase in Fe(2+) concentration or supplemental illumination improves the growth stability of R. capsulatus.  相似文献   
69.
The objective of the present study was to describe plasma hormonal and metabolite profile and mRNA expression levels and activities of the enzymes pyruvate carboxylase (PC), phosphoenolpyruvate carboxykinase (PEPCK), and acetyl-coenzyme A (CoA) carboxylase in the liver of male Holstein calves before (1 and 3 wk of age) and after (8, 13, and 19 wk of age) weaning at 6 wk of age. The mean plasma concentration of acetate and β-hydroxybutyrate increased, and that of plasma lactate and nonesterified fatty acids decreased with week, particularly after weaning. Plasma glucose concentration was lowest at 8 wk of age. The mean plasma concentration of insulin and glucagon did not change with time, and that of cortisol was greatest at 1 wk of age. In the liver, enzyme activity of PC was greatest at 1 wk of age and decreased with time. There was a significant relationship between the activity and the mRNA level for PC. Activity of PEPCK also decreased with week. Acetyl-CoA carboxylase activity tended to decrease with week, and activity at 13 wk of age was lower than that at other times. Expression of PC mRNA, but not that of PEPCK and acetyl-CoA carboxylase α, decreased with week. We conclude that the hepatic gluconeogenic enzymes and acetyl-CoA carboxylase activities tend to decrease with age, reflecting changes in plasma metabolites in early weaning production systems.  相似文献   
70.
The response of polycrystalline TiB2 to neutron irradiation was investigated. The material was fabricated using isotopically enriched 11B powders to minimize helium production via the 10B(n, α)7Li reaction. Neutron irradiation was conducted at temperatures of ~200°C and ~600°C to a fast fluence of 2.4 × 1025 n/m2 (>0.1 MeV). The material exhibited some swelling, but less swelling at the higher irradiation temperature. No macroscopic damage was observed in the irradiated material, although moderate irradiation-induced micro-cracking was found in the irradiated TiB2. This study demonstrated improved radiation resistance of isotopically tailored TiB2 compared with natural boron TiB2, which exhibited macroscopic fracture by irradiation.  相似文献   
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