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Biomedical subjects

T M Wilkinson

Publications and source records attributed to T M Wilkinson.

14 recordsLinked to original sources
PubMed1994

A histologic study of retrodiscal tissues of the human temporomandibular joint in the open and closed position.

Specialized roles for the different components of the retrodiscal tissues have been previously postulated. This study compared the histologic features of the retrodiscal tissues of temporomandibular joints, taken from human cadavers, in the open and closed position; it was concluded that the primary role of these components was to provide a volumetric compensatory mechanism for pressure equilibration. This mechanism was still active in joints that demonstrated disc displacement and degenerative changes. Elastin was found in the upper and lower strata of the retrodiscal tissues, as well as in the central zone. The concept of an elastic upper stratum that has a recoil mechanism to control disc movement was not supported by this study, as the upper stratum was folded on itself in the closed position and only became stretched near maximal opening.

Aged↗
PubMed1990

Silent periods in dysfunction patients: a preliminary study using a novel approach.

Strong peri-oral stimulation is known to elicit a transient inhibition in the activity of the jaw-closing muscles. Several reports have claimed that this 'silent period' (SP) is prolonged in patients with temporomandibular joint dysfunction syndromes. In the present preliminary study, the biphasic SP evoked by electrical lip stimulation was tested in single motor units in the masseter muscles of dysfunction patients. In comparison with normal subjects, the pattern of the SP was different in the patients in that the shorter-latency phase predominated over the later phase, whereas the converse is true for normals.

Electric Stimulation↗
PubMed1989

A comparison of the masseteric silent period in temporomandibular joint dysfunction and normal human subjects by surface electromyography and single motor-unit recordings.

Single electric stimuli were delivered to the lower lip and the reflex effects were monitored in the ipsilateral masseter. Two strengths of stimulus were delivered at two levels of background excitation (defined in terms of the firing frequency of a single motor unit). Although the threshold stimulus intensity required to produce a silent period in the single motor units was the same for the patients with temporomandibular joint dysfunction and normal subjects, there were qualitative differences in the pattern of reflex responses between the two groups. Of the two phases of inhibition elicited by the stimulus, the short-latency inhibitory period was the more prominent and more resistant to changes in the background excitation levels in the dysfunction group. In normal subjects, however this was true of the long-latency inhibition. This difference may be due to the changes in the inputs to one or more of the interneurones linking the afferent limb of the reflex to the masseteric motoneurones.

Adult↗
PubMed1989

The recognition of craniomandibular disorders--an evaluation of the most reliable signs and symptoms when screening for CMD.

Two hundred and twenty-two patients who had been examined and treated for craniomandibular disorders were re-evaluated using a screening protocol. This protocol was developed from previous studies which had elucidated the most reliable signs and symptoms of craniomandibular disorders. Unilateral signs and symptoms were found to be more common than bilateral signs and symptoms. Dynamic and static pain tests were shown to be decisive in determining the preliminary diagnosis. There was a significant difference in vertical condylar height asymmetry between those patients diagnosed as having a myogenous and an arthrogenous origin of pain.

Adult↗
PubMed1982

Limitation of jaw movement by antagonist muscle stiffness during unloading of human jaw closing muscles.

The unloading reflex in the jaw closing muscles in man was investigated with a view to correlating the jaw closing movement with the timing of the electrical activity of the agonist and antagonist muscles. When the resistance to the forceful isometric bite was suddenly and unexpectedly withdrawn, the closing movement of the mandible was always arrested before the teeth came together. The rapid arrest of the jaw closing movement was not adequately accounted for by the timing of the inhibition of the jaw closing muscles and reflex excitation of the jaw opening muscles. It was observed that the jaw opening muscles, as well as the jaw closing muscles, were always active during the phase of isometric biting on an object between the teeth. It is therefore concluded that the resulting stiffness of the antagonist muscles is the mechanism which is principally responsible for limiting the jaw closing movement after unloading of the agonist muscles.

Adult↗
PubMed1979

Isolation of glycophorin with deoxycholate.

In a previous communication we reported that human erythrocyte glycophorin prepared by the lithium diiodosalicylate phenol procedure contains approximately 10 mol of lithium diiodosalicylate per mol of glycophorin, and further we showed that this bound lithium diiodosalicylate is difficult to remove by detergents or organic solvents (Romans, A.Y. and Segrest, J.P. (1978) Biochim. Biophys. Acta 511, 297-301). In the present communication we report an alternative purification procedure for glycophorin in which sodium deoxycholate is substituted for lithium diiodosalicylate; the sodium deoxycholate is subsequently removed by gel filtration. Utilizing this procedure, 25-30 mg glycophorin are obtained per gram of lyophilized erythrocyte ghosts. The glycophorin prepared by the sodium deoxycholate procedure, after a single gel filtration step, contains less than 1 mol of sodium deoxycholate per mol glycophorin and is colorless compared with glycophorin prepared by the lithium diiodosalicylate procedure, which has a distint reddish-brown cast.

Chromatography, Gel↗
PubMedDate not supplied

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Anecdotes as Topic↗