Orthodontic fine adjustment after vertical callus distraction of an ankylosed incisor using the floating bone concept.

The outcome of vertical callus distraction of a segment of tooth-supporting alveolar process might be functionally and esthetically unsatisfactory because of the unidirectional impact of intraoral distraction devices. In this case report, we describe how, with a shortened consolidation phase and application of the floating bone effect, the tooth-supporting osteotomy segment can be successfully aligned 3 dimensionally. We applied orthodontic force systems that went beyond the unidirectional vector preset by the mechanical properties of the distraction device.     

Cardiac efficiency and oxygen consumption measured with 11C-acetate PET after long-term cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) is a treatment option in patients with severe heart failure and left bundle-branch block (LBBB). This study evaluated the effects of 4 and 13 mo of CRT on myocardial oxygen consumption (MVO2) and cardiac efficiency as compared with mild heart failure patients without LBBB. METHODS: Sixteen patients with severe heart failure and LBBB due to idiopathic cardiomyopathy were studied at baseline and after 4 and after 13 mo of therapy. Thirteen patients with mild heart failure without LBBB served as a comparison group. The clearance rate (k2) of 11C-acetate was measured with PET to assess MVO2. Stroke volume was derived from the dynamic PET data according to the Stewart-Hamilton principle and, furthermore, cardiac efficiency using the work metabolic index. RESULTS: After 4 mo of CRT, stroke volume index (SVI) increased by 50% (P = 0.012) and cardiac efficiency increased by 41% (P < 0.001). Global k2 remained unchanged but regional k2 demonstrated a more homogeneous distribution pattern. The parameters showed no significant changes during therapy. Under CRT, cardiac efficiency, SVI, and the distribution pattern of regional k2 did not differ from mild heart failure patients without LBBB. CONCLUSION: CRT improves cardiac efficiency for at least 13 mo, as demonstrated by a higher SVI, whereas MVO2 remains unchanged. Cardiac efficiency, SVI, and the MVO2 distribution pattern reach the level of patients with mild heart failure without LBBB. The unfavorable hemodynamic performance in heart failure with LBBB is effectively restored by long-term CRT to the level of an earlier disease state.     

Normative values of bone parameters of children and adolescents using digital computer-assisted radiogrammetry (DXR).

PURPOSE: To verify whether estimation of bone mineral density (BMD) using digital X-ray radiogrammetry (DXR) is possible on children and to determine normative values of both such a DXR-BMD estimate and a corresponding metacarpal index (DXR-MCI) on. PATIENTS AND METHODS: In retrospect, X-rays were selected of the hands of 200 healthy Caucasian children (120 boys and 80 girls, aged 4-18 yr). The involved children were selected among a larger group of children submitted to the surgical department of our institute for evaluation of a suspected fracture after an occurred trauma. All children with a verified fracture or a chronic bone-related disease, including bone age retardation or acceleration, were excluded from the study. Furthermore, only conventional X-rays with the same film and capture parameters were included. The images were scanned and analyzed using the Pronosco X-posure system V.2 (Sectra Pronosco, Denmark). DXR-BMD, DXR-MCI, and a porosity index (DXR-PI) were automatically calculated using the midshafts of the metacarpals II-IV. Mean values of DXR-BMD and DXR-MCI were calculated separately for girls and boys in 2-yr intervals. RESULTS: In the present study the system has been demonstrated to be capable of calculating DXR-BMD from conventional X-rays of the hand from children down to approx 6 yr of age. This ability depended somewhat on the diameter and the length of the involved metacarpals. The success rate was higher for large bones than for small bones. The system succeeded in analyzing the images of 110 boys and 68 girls. Values of DXR-BMD were observed to increase with age from 0.40 g/cm2 to 0.62 g/cm2 in the male group and from 0.39 g/cm2 to 0.54 g/cm2 in the female group. Girls aged 11-12 yr had a higher DXR-BMD than did boys, corresponding to the earlier entry to puberty of girls. Standard deviations (SDs) reached values of up to 0.05 g/cm2. DXR-MCI increased with age from 0.36 to 0.47 for boys and from 0.34 to 0.49 for girls with a maximum SD of 0.06. The correlation between DXR-BMD and age was r=0.83 and r=0.84 for boys and girls, respectively. The corresponding correlations for DXR-MCI was lower, with observed correlations of r=0.63 (boys) and r=0.68 (girls), respectively, with p<0.01 in all cases. The DXR-PI did not reveal a significant correlation to age (r=-0.31 and r=0.04. respectively) and showed SDs marginally higher than the calculated mean values. CONCLUSION: The newly available DXR-methodology seems to offer the ability to determine DXR-BMD and DXR-MCI in children starting with a bone age of 6. This possibility may be of special relevance for children suffering from chronic bone diseases that require repeated X-rays of the hand (e.g. to determine bone age). The acquired normative data suggest that the measurements are of clinical value owing to low age-dependent variability (SDs) relative to an observed high increase with age. The clinical value of the porosity index (DXR-PI) remains uncertain and is limited owing to a high inter-individual variability.     

Propofol and Sevoflurane in Subanesthetic Concentrations Act Preferentially on the Spinal Cord: Evidence from Multimodal Electrophysiological Assessment

Background: Animal experiments in recent years have shown that attenuation of motor responses by general anesthetics is mediated at least partly by spinal mechanisms. Less is known about the relative potency of anesthetic drugs in suppressing cortical and spinal electrophysiological responses in vivo in humans, particularly those, but not only those, connected with motor responses. Therefore, we studied the effects of sevoflurane and propofol in humans using multimodal electrophysiological assessment.

Methods: We studied nine healthy volunteers in two sessions during steady state sedation with 0.5, 1.0, and 1.5 [mu]g/l (targeted plasma concentration) propofol or 0.2 and 0.4 vol% (end-tidal) sevoflurane. Following a 15-min equilibration period, motor responses to transcranial magnetic stimulation and peripheral (H-reflex, F-wave) stimulation were recorded, while electroencephalography and auditory evoked responses were recorded in parallel.

Results: At concentrations corresponding to two thirds of C50 awake, motor responses to transcranial magnetic stimulation were reduced by approximately 50%, H-reflex amplitude was reduced by 22%, F-wave amplitude was reduced by 40%, and F-wave persistence was reduced by 25%. No significant differences between sevoflurane and propofol were found. At this concentration, the Bispectral Index was reduced by 7%, and the middle-latency auditory evoked responses were attenuated only mildly (Nb latency increased by 11%, amplitude PaNb did not change). In contrast, the postauricular reflex was suppressed by 77%.     

Velocity and flow quantitation in the superior sagittal sinus with ungated and cine (gated) phase-contrast MR imaging

Normal blood flow and velocity in the superior sagittal sinus were measured in 30 patients. A fast two-dimensional ungated phase-contrast (PC) pulse sequence was compared with a peripherally gated cine PC technique for velocity and flow quantitation. The same imaging parameters were used for both methods. Measured values for mean velocity and flow obtained with the two methods were compared by using regression analysis and t testing. For blood flow, the correlation coefficient was 0.976. For velocity measurements, r was 0.950. Mean flow was 285 mL/min ± 19 with the ungated PC method and 281 mL/min ± 19 with the cine PC method. The mean velocities measured with the two methods were 12.94 cm/sec ± 1.1 and 13.59 cm/sec ± 1.1, respectively. There was no significant difference (paired t test) between the methods for mean flow or velocity data. This was true even though flow in the superior sagittal sinus is moderately pulsatile, as shown with the cine PC technique. The ungated PC method provided these data in 13 seconds versus 3.5 minutes for the cine PC method.     

Fibre type characteristics of the lumbar paraspinal muscles in normal healthy subjects and in patients with low back pain

A knowledge of the alteration in the fibre type profile of paraspinal muscle associated with low back pain is essential for the design of successful rehabilitation programmes. In attempting to compare the muscles of patients with low back pain with those of controls, few previous studies have considered factors such as gender, age, and size of the subjects, each of which can potentially confound interpretation of the results. We obtained samples of lumbar paraspinal muscle during spinal surgery from 21 patients with low back pain and, using the percutaneous biopsy technique, from 21 control volunteers matched for gender, age, and body mass. The samples were subject to routine histochemicsl typcal analysis to determine characteristics of muscle fibre type. Compared with controls, the muscle of the patients had a significantly higher proportion of type-IIB (fast-twitch glycolytic) fibres than type- I (slow oxidatve) fibres. The mean size of a given fibre type did not differ between the patients and the controls. Consequently, the relative area of the muscle iccupied by type-IIB fibres was higher and that by type-I fibres Was lower in the patients. The patients had a greater number of muscle samples with more than 1% type-IIC fibres, and abnormalities that could be described as pathological were more marked in the patients than in the controls. In conclusion, the paraspinal muscles of patients who have low back pain display a more glycolytic (faster) profile; this can be expected to render them less resistant to fatigue.