Tracking ability in subjects symptomatic of cumulative trauma disorder: does it relate to disability?

Symptoms of upper extremity cumulative trauma disorders (CTDs) often include weakness, discomfort, pain, numbness and stiffness, which are generally assessed clinically by using static tests or isolated movements. Little is known about the dynamic, functional ability of the upper extremity in CTD, yet, more than impairment, performance variables may relate to disability. The objectives of this study were to determine whether a manual tracking task was sensitive to the presence of symptoms associated with CTD and whether tracking performance related to disability. Forty-five volunteers who had frequently experienced one or more symptoms consistent with upper extremity CTD for at least 1 year and 22 control subjects performed the manual tracking task. Using a hand-held stylus over a digitizing tablet, subjects tracked a target that moved pseudo-randomly and was displayed on a computer screen. The root mean square error of the linear difference between target and stylus positions provided a measure of overall performance accuracy. Quadrant specific performance was also calculated to determine whether the location of the target (hence hand and wrist position) influenced performance. Additionally, the symptomatic group completed the Disability of the Arm, Shoulder and Hand (DASH) questionnaire reflecting physical disability level. Performance accuracy was poorer in symptomatic subjects than controls (p<0.001) and was influenced by target location (p<0.0001). The overall performance was associated with physical disability (r = 0.54). The findings suggest that tracking performance is sensitive to the presence of CTD symptoms and related to disability level. Further validation is required to determine whether the performance measure is sensitive to disease progression or intervention-induced changes.

Iron and aluminum deposition in the meninges of the lamprey: identification of an aluminum-ferritin inclusion body.

The meningeal tissue of the brain and spinal cord of larval and juvenile adults of lampreys (Petromyzon marinus) was examined by routine electron microscopy, electron microscopic histochemistry, and electron-probe x-ray microanalysis to locate sites of iron deposition. A magnetometer was used for identification of ferromagnetic iron. Ferritin particles, representing ferric iron, are present in abundance within the cytoplasmic matrices and in dense bodies of meningeal cells of both the brain and spinal cord of larvae and juveniles. These round cells of the meninges also contain abundant glycogen and lipid. Small quantities of ferrous iron are associated to the latter inclusion. Aluminum deposits are present within an electron-dense material of many ferritin-containing inclusions of meningeal cells of the larval brain. Ferromagnetic material was not detected in larval and upstream-migrant lampreys. The deposition of iron and aluminum in the meninges of lampreys may be related to physiological and environmental factors, respectively, and/or to an important interaction between the two metals.

Changes in the distribution of fast and slow forms of troponin I in some neuromuscular disorders.

As judged from the atrophy of the muscle cells, the distribution of slow and fast troponin I in type I and type II cells in peripheral neuropathies in the adults (24-67 years of age) was unaffected for long periods after denervation. Reinnervation by fast or slow nerve in chronic neuropathies usually resulted in typical fibre type grouping with complete segregation of slow and fast troponin I in type I and type II cells, respectively. Intermediate fibres (slow and fast troponin I in the same cell) were present during the course of transformation. Unlike peripheral neuropathies, the number of cells staining for slow troponin I in the very atrophic fascicles in spinal muscular atrophy was considerably reduced. The synthesis of fast troponin I was stimulated in original type I cells containing slow troponin I. These observations support the experimental data (Dhoot and Perry 1982b) that the suppression of fast troponin I in type I or presumptive type I cells requires innervation by the slow nerve. Its absence results in an increased expression of fast troponin I in cells that originally contained only slow troponin I. Once suppressed, fast troponin I is absent in type I cells even after long periods of experimental denervation or cases of human peripheral neuropathies but not so in the cases of spinal muscular atrophy.

Transformation of fibre types in muscular dystrophies.

In the normal human skeletal muscle, slow and fast forms of troponin I are segregated in type I and type II cells, respectively. Muscle biopsies from different dystrophies showed a large number of intermediate cells that stained with antibodies to both fast and slow troponin I. Intermediate cells of variable size were scattered at random and did not show a motor unit distribution as generally seen in some neuromuscular disorders. The preponderance of a particular cell type depended on the type of dystrophy. Except for dystrophia myotonica, all cases showed presence of small cells that looked like regenerating cells.

Scoliosis: a rare manifestation of intrinsic tumours of the spinal cord in children.

Three cases are described of apparent idiopathic scoliosis in childhood which were shown subsequently to be due to intramedullary spinal cord tumour. The possibility of this underlying lesion should be considered in any child who develops scoliosis without an obvious cause.

Magnetic properties of lunar samples.

A breccia sample (10023) from the moon was found to have a strong and fairly stable remanent magnetization. If this sample was not magnetized by local fields in the spacecraft or in the lunar receiving laboratory, it must have been magnetized on the moon. This could have happened in a variety of ways, such as cooling through the Curie temperature, by comitinuous thermal cycling, or by impact, but all of these require the presence ofr a magnetic field. Such a field could have been of internal origin in the moon, or it could have been a residual effect from the earth's magnetic field at a time when the moon and the earth were much closer together. Thermomagnetic studies identify the presence of iron with about 1 percent nickel (igneous). iron with abiout 5 to 10 percent nickel (meteoritic), iron with about 33 percent or more nickel (meteoritic), and ilmenite.

A standard and rapid method for determining nozzle-tip abrasion.

The wear resistance of nozzle tips used in malaria eradication programmes has, in the past, been measured with water suspensions of a variety of wettable powder insecticides. The abrasive powers of these suspensions vary greatly, and it is therefore impossible to relate the results of one test to those of another. A standard method has been devised in which a suspension of a standard synthetic powder with a high silica content is forced through nozzles, once, at 40 lbf/in(2) (2.81 kgf/cm(2)). The method is reliable, reproducible, and rapid, and it may also be used to evaluate the abrasiveness of water-wettable insecticide powders.