Neurophysiology of epidurally evoked spinal cord reflexes in clinically motor-complete posttraumatic spinal cord injury

Increased use of epidural Spinal Cord Stimulation (eSCS) for the rehabilitation of spinal cord injury (SCI) has highlighted the need for a greater understanding of the properties of reflex circuits in the isolated spinal cord, particularly in response to repetitive stimulation. Here, we investigate the frequency-dependence of modulation of short- and long-latency EMG responses of lower limb muscles in patients with SCI at rest. Single stimuli could evoke short-latency responses as well as long-latency (likely polysynaptic) responses. The short-latency component was enhanced at low frequencies and declined at higher rates. In all muscles, the effects of eSCS were more complex if polysynaptic activity was elicited, making the motor output become an active process expressed either as suppression, tonic or rhythmical activity. The polysynaptic activity threshold is not constant and might vary with different stimulation frequencies, which speaks for its temporal dependency. Polysynaptic components can be observed as direct responses, neuromodulation of monosynaptic responses or driving the muscle activity by themselves, depending on the frequency level. We suggest that the presence of polysynaptic activity could be a potential predictor for appropriate stimulation conditions. This work studies the complex behaviour of spinal circuits deprived of voluntary motor control from the brain and in the absence of any other inputs. This is done by describing the monosynaptic responses, polysynaptic activity, and its interaction through its input–output interaction with sustain stimulation that, unlike single stimuli used to study the reflex pathway, can strongly influence the interneuron circuitry and reveal a broader spectrum of connectivity.

Quantitative and sensitive assessment of neurophysiological status after human spinal cord injury

OBJECT

This study was designed to develop an objective and sensitive spinal cord injury (SCI) characterization protocol based on surface electromyography (EMG) activity.

METHODS

Twenty-four patients at both acute and chronic time points post-SCI, as well as 4 noninjured volunteers, were assessed using neurophysiological and clinical measures of volitional motor function. The EMG amplitude was recorded from 15 representative muscles bilaterally during standardized maneuvers as a neurophysiological assessment of voluntary motor function. International Standards for the Neurological Classification of Spinal Cord Injury (ISNCSCI) examinations were performed as a clinical assessment of lesion severity.

RESULTS

Sixty-six functional neurophysiological assessments were performed in 24 patients with SCI and in 4 neurologically intact individuals. The collected EMG data were organized by quantitative parameters and statistically analyzed. The correlation between root mean square (RMS) of the EMG signals and ISNCSCI motor score was confirmed by Kendall correlation analysis. The Kendall correlation value between overall muscles/levels, motor scores, and the RMS of the EMG data is 0.85, with the 95% CI falling into the range of 0.76-0.95. Significant correlations were also observed for the soleus (0.51 [0.28-0.74]), tibialis anterior (TA) (0.53 [0.33-0.73]), tricep (0.52, [0.34-0.70]), and extensor carpi radialis (ECR) (0.80 [0.42-1.00]) muscles. Comparisons of RMS EMG values in groups defined by ISNCSCI motor score further confirmed these results. At the bicep and ECR, patients with motor scores of 5 had nearly significantly higher RMS EMG values than patients with motor scores of 0 (p = 0.059 and 0.052, respectively). At the soleus and TA, the RMS of the EMG value was significantly higher (p < 0.01) for patients with American Spinal Injury Association Impairment Scale motor scores of 5 than for those with ISNCSCI motor scores of 0. Those with C-7 ISNCSCI motor scores of 5 had significantly higher RMS EMG values at the tricep than those with motor scores of 4 (p = 0.008) and 0 (p = 0.02). Results also show that surface EMG signals recorded from trunk muscles allowed the examiner to pick up subclinical changes, even though no ISNCSCI scores were given.

CONCLUSIONS

Surface EMG signal is suitable for objective neurological SCI characterization protocol design. The quantifiable features of surface EMG may increase SCI characterization resolution by adding subclinical details to the clinical picture of lesion severity and distribution.

High resolution chromosome 3p allelotyping of human lung cancer and preneoplastic/preinvasive bronchial epithelium reveals multiple, discontinuous sites of 3p allele loss and three regions of frequent breakpoints

Allele loss involving chromosome arm 3p is one of the most frequent and earliest known genetic events in lung cancer pathogenesis and may affect several potential tumor suppressor gene regions. To further study the role of chromosome 3p allele loss in the pathogenesis of lung cancer, we performed high resolution loss of heterozygosity (LOH) studies on 97 lung cancer and 54 preneoplastic/preinvasive microdissected respiratory epithelial samples using a panel of 28 3p markers. Allelic losses of 3p were detected in 96% of the lung cancers and in 78% of the preneoplastic/preinvasive lesions. The allele losses were often multiple and discontinuous, with areas of LOH interspersed with areas of retention of heterozygosity. Most small cell lung carcinomas (91%) and squamous cell carcinomas (95%) demonstrated larger 3p segments of allele loss, whereas most (71%) of the adenocarcinomas and preneoplastic/preinvasive lesions had smaller chromosome areas of 3p allele loss. There was a progressive increase in the frequency and size of 3p allele loss regions with increasing severity of histopathological preneoplastic/preinvasive changes. In analyses of the specific parental allele lost comparing 42 preneoplastic/preinvasive foci with those lost in the lung cancer in the same patient (n = 10), the same parental allele was lost in 88% of 244 comparisons for 28 3p markers (P = 1.2 x 10(-36) for this occurring by chance). This indicates the occurrence of allele-specific loss in these foci similar to that seen in the tumor by a currently unknown mechanism. Analysis of all of the data indicated multiple regions of localized 3p allele loss including telomere-D3S1597, D3S1111-D3S2432, D3S2432-D3S1537, D3S1537, D3S1537-D3S1612, D3S4604/Luca19.1-D3S4622/Luca4.1, D3S4624/Luca2.1, D3S4624/Luca2.1-D3S1582, D3S1766, D3S1234-D3S1300 (FHIT/FRA3B region centered on D3S1300), D3S1284-D3S1577 (U2020/DUTT1 region centered on D3S1274), and D3S1511-centromere. A panel of six markers in the 600-kb 3p21.3 deletion region showed loss in 77% of the lung cancers, 70% of normal or preneoplastic/preinvasive lesions associated with lung cancer, and 49% of 47 normal, mildly abnormal, or preneoplastic/preinvasive lesions found in smokers without lung cancer; however, loss was seen in 0% of 18 epithelial samples from seven never smokers. The 600-kb 3p21.3 region and the 3p14.2 (FHIT/FRA3B) and 3p12 (U2020/DUTT1) regions were common, independent sites of breakpoints (retention of heterozygosity by some markers and LOH by other markers in the immediate region). We conclude that 3p allele loss is nearly universal in lung cancer pathogenesis; involves multiple, discrete, 3p LOH sites that often show a "discontinuous LOH" pattern in individual tumors; occurs in preneoplastic/preinvasive lesions in smokers with and without lung cancer (multiple lesions often lose the same parental allele); frequently involves breakpoints in at least three very small defined genomic regions; and appears to have allele loss and breakpoints first occurring in the 600-kb 3p21.3 region. These findings are consistent with previously reported LOH studies in a variety of tumors showing allele loss occurring by mitotic recombination and induced by oxidative damage.

Empowerment in general practice. The trilogies of caring

The authors examine the way in which the doctor-patient interaction often varies between an oppressive caring mode and an oppressed caring mode, both of which apply pressures to the participants and prevent good quality care. A model for the trilogy of oppressive, oppressed, and empowerment caring is examined and it is explained how the process of empowerment caring can enhance the general practitioners' quality of care and improve their practice, their home life and their personal wellbeing.

Does non-clinical decompression stress lead to brain damage in abalone divers?

Abalone divers are subject to considerable decompression stresses and could be at risk of progressive cognitive impairment. A sample of abalone divers was compared with a sample of fishermen, by means of a battery of neuropsychological tests. No evidence of cognitive impairment was found in the divers, in spite of evidence of their exposure to decompression stress. The implications for other professional divers and for recreational underwater divers who follow standard decompression protocols are reassuring.

Results of large scale media antismoking campaign in Australia: North Coast "Quit for Life" programme

A three community study was carried out in northern New South Wales, Australia, to determine the effectiveness of interventions via media and media plus community programmes in altering behaviours of life style, including smoking, dietary fat intake, and exercise. Results were analysed of one aspect of the "North Coast Healthy Lifestyle Programme" entitled "Quit for Life," which aimed at reducing cigarette smoking over a two year period. There was a significant decline in the prevalence of smoking in both test towns, ranging from 16% in younger men to 6% in older women. These were significantly greater than the declines in the control town. The declines were more sustained over the two year period in the town subjected to media plus community programmes.