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AIMS: The aim of this study was to determine the influence of developmental spinal stenosis (DSS) on the risk of re-operation at an adjacent level. PATIENTS AND METHODS: This was a retrospective study of 235 consecutive patients who had undergone decompression-only surgery for lumbar spinal stenosis and had a minimum five-year follow-up. There were 106 female patients (45.1%) and 129 male patients (54.9%), with a mean age at surgery of 66.8 years (sd 11.3). We excluded those with adult deformity and spondylolisthesis. Presenting symptoms, levels operated on initially and at re-operation were studied. MRI measurements included the anteroposterior diameter of the bony spinal canal, the degree of disc degeneration, and the thickness of the ligamentum flavum. DSS was defined by comparative measurements of the bony spinal canal. Risk factors for re-operation at the adjacent level were determined and included in a multivariate stepwise logistic regression for prediction modelling. Odds ratios (ORs) with 95% confidence intervals were calculated. RESULTS: Of the 235 patients, 21.7% required re-operation at an adjacent segment. Re-operation at an adjacent segment was associated with DSS (p = 0.026), the number of levels decompressed (p = 0.008), and age at surgery (p = 0.013). Multivariate regression model (p < 0.001) controlled for other confounders showed that DSS was a significant predictor of re-operation at an adjacent segment, with an adjusted OR of 3.93. CONCLUSION: Patients with DSS who have undergone lumbar spinal decompression are 3.9 times more likely to undergo future surgery at an adjacent level. This is a poor prognostic indicator that can be identified prior to index decompression surgery.

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AIMS: We report the use of the distal radius and ulna (DRU) classification for the prediction of peak growth (PG) and growth cessation (GC) in 777 patients with idiopathic scoliosis. We compare this classification with other commonly used parameters of maturity. PATIENTS AND METHODS: The following data were extracted from the patients' records and radiographs: chronological age, body height (BH), arm span (AS), date of menarche, Risser sign, DRU grade and status of the phalangeal and metacarpal physes. The mean rates of growth were recorded according to each parameter of maturity. PG was defined as the summit of the curve and GC as the plateau in deceleration of growth. The rates of growth at PG and GC were used for analysis using receiver operating characteristic (ROC) curves to determine the strength and cutoff values of the parameters of growth. RESULTS: The most specific grades for PG using the DRU classification were radial grade 6 and ulnar grade 5, and for GC were radial grade 9 and ulnar grade 7. The DRU classification spanned both PG and GC, enabling better prediction of these clinically relevant stages than other methods. The rate of PG (≥ 0.7 cm/month) and GC (≤ 0.15 cm/month) was the same for girls and boys, in BH and AS measurements. CONCLUSION: This is the first study to note that the DRU classification can predict both PG and GC, providing evidence that it may aid the management of patients with idiopathic scoliosis. Cite this article: Bone Joint J 2016;98-B:1689-96.

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In vertebrate neuromuscular junctions, acetylcholinesterase (AChE; EC 3.1.1.7) is highly concentrated at the synaptic basal lamina and the postsynaptic muscle fiber. The postsynaptic muscle cell is the primary source of AChE. However, several lines of evidence indicate that the presynaptic motor neuron is able to synthesize and secrete AChE at the neuromuscular junctions. By using anti-AChE monoclonal antibody in immunohistochemical staining, we found that the AChE-positive cells were labeled only at the motor neurons of the chick spinal cords. When the protein extract of chick spinal cords was analyzed by a Western blot analysis, a protein band of approximately 105 kDa was recognized. In denervated chicks, the expression of motor neuron AChE, as recognized on a Western blot, decreased by approximately 50% 4 days after denervation. The AChE expression in denervated chick spinal cords, however, was restored to control level 10 days after denervation. The decreased AChE expression was restricted to the ipsilateral side of the denervated chick spinal cord while the contralateral side was relatively unchanged. In comparison with the contralateral side, the level of AChE protein and enzymatic activity expressed in the ipsilateral spinal cord was approximately 50% lower. This is the first demonstration to show that the ipsilateral and contralateral sides of chick spinal cords respond differently after nerve denervation.

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A model of pulse oximetry is developed based on the three-dimensional photon diffusion theory. To test the applicability of the model, an in vitro assay was developed. Three different scattering levels and six different relative dye concentrations were analyzed. Average percent errors of 13.9% were obtained over the full range of the study. An in vivo clinical study of two pulse oximeter probes with different spectral characteristics was compared with results estimated by the model. The model correctly predicted the changes in pulse oximeter response resulting from the wavelength changes. A x(2) test gave a probability of 20% that the model fit the data. These results demonstrated the utility of the photon diffusion theory for the modeling of tissue optics.

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The purpose of this study was to characterize the accuracy and dynamic response characteristics of traditional transmittance pulse oximeters and a new reflectance pulse oximeter with regard to the current standard in oximetry, the Hewlett-Packard ear oximeter. Studies were performed with 15 healthy male and female subjects. A rebreathing technique was employed to produce a steady fall in oxygen saturation and to maintain constant, eucapnic, end-tidal CO2 levels. The oximeters' analog outputs were recorded by a Western Graphtec Linearecorder and by an IBM-PC utilizing an analog-to-digital converter for data collection at 5 Hz. The agreement between two clinical methods of measurement was used as the statistical technique of comparing new technology (pulse oximetry) with the current standard (Hewlett-Packard ear oximetry). The mean of the difference between the Hewlett-Packard and the pulse oximeter with reflectance sensor was 0.28%, with a range of difference of +/- 3.49%. This value was similar to that of the transmittance oximeters (Criticare 501+: 0.92 +/- 2.11), (Physio-Control: 3.15 +/- 2.04), (Ohmeda 3700: 2.05 +/- 2.06). There was virtually no response-time difference between the reflectance oximeter with the sensor placed on the subject's forehead and the Hewlett-Packard ear oximeter. The authors conclude that the accuracy of the reflectance oximeter is within the limits of clinical acceptance for monitoring and trending of arterial oxygen saturation in healthy subjects.

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Estimates of oxygenation from three transmittance oximeters, Hewlett-Packard 47201A, Nellcor, and Biox III, were obtained simultaneously in ten healthy human subjects during isocapnic progressive hypoxia and under conditions of episodic hypoxemia. In the oxygen saturation range studied (approximately 95-75%), results showed that values from the Nellcor finger oximeter were 2-4% lower than values from the Hewlett-Packard ear oximeter. Values from the Biox III oximeter, using either the ear or finger probe, were 3-7% higher than those from the Hewlett-Packard, and the biggest discrepancies were seen as oxygen saturation fell below 80%. This often resulted in an estimation of the ventilatory response to hypoxia as measured using the Biox III oximeter that was higher than estimates using the Nellcor or the Hewlett-Packard (P less than 0.005). Hypoxic ventilatory responses using the Nellcor and the Hewlett-Packard oximeters gave similar values. During rapidly changing oxygenation, the distribution of values for oxygen saturation were significantly different for the three oximeters. For example, the median of the distribution for Nellcor values was 89 +/- 1.5% (mean +/- SEM); for the Hewlett-Packard, it was 92 +/- 1.3%; and for the Biox III, it was 93 +/- 0.8% (finger) and 95 +/- 1.6% (ear). The authors conclude that differences between the three non-invasive transmittance oximeters will affect clinical measurement of the ventilatory responsiveness to hypoxia and the estimation of the stimulus for hypoxic complications in respiratory diseases.

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Female rats exposed to low intensities (0.1-1.5 lx) of continuous light (LL), displayed regular estrous cycles and free-running circadian rhythms of locomotor activity. In most rats, as the intensity of LL was increased to greater than 2.0 lx, components within the active portion (alpha) of the locomotor rhythm remained synchronized as the periodicity of the rhythm lengthened. However, in a few rats alpha split into two components; one of which free-ran with a period shorter than 24 h, while the other free-ran with a period longer than 24 h. As soon as the two components became maximally separated they spontaneously rejoined. In most rats, estrous cycles ceased shortly after the intensity of LL was increased to greater than 2.0 lx even though the locomotor activity rhythm retained its unsplit free-running nature. These observations suggest that the multiple oscillators that control the rhythms of locomotor activity and the estrous cycle are normally coupled to one another. In certain intensities of LL, these oscillators uncouple and free-run with different periodicities, a condition which causes estrous cycles to cease and sometimes produces a split locomotor activity rhythm.

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A new method to estimate arterial oxygen saturation is suggested based on the presence of the plethysmographic pulse. A prototype skin reflectance oximeter system utilizing a miniature solid state optical transducer has been constructed. Preliminary data collected from a group of volunteers indicated good quantitative correlation between skin reflectance and arterial oxygen saturation as determined by an earlobe oximeter. We are now investigating the dependency of the measurements on various physiological conditions and skin characteristics in order to determine appropriate calibration procedures. This study has demonstrated for the first time that arterial hemoglobin oxygen saturation can be measured quantitatively using transcutaneous reflectance techniques. However, more extensive work is needed to further develop this technique into a viable clinical tool.

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These experiments were undertaken to determine if the pineal gland is involved in the physiological mechanism by which the rat alters its free-running period (tau) in response to changes in illuminance. Spontaneous wheel-running activity was recorded from pinealectomized or sham-operated female Charles River rats. The tau of running activity was determined in continuous darkness (DD) or in continuous dim light (LL). Pinealectomized rats and sham-operated rats lengthened their tau's to approximately the same extent when shifted from DD to LL and shortened their tau's when shifted back to DD. Continuous melatonin administration via Silastic capsules failed to alter tau of rats kept in dim LL. These results indicate that the pineal is not primarily involved in the mechanism by which the rat alters tau in response to changes in illuminance.

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