Reversal of rigidity and improvement in motor performance by subthalamic high-frequency stimulation in MPTP-treated monkeys

In Parkinson's disease the loss of dopaminergic neurons in the substantia nigra is associated with global disorganization of basal ganglia activity and, in particular, with increased activity of the excitatory glutamatergic neurons of the subthalamic nucleus. Recent experimental studies have shown that parkinsonian symptoms can be alleviated by selective lesioning of the subthalamic nucleus in monkeys treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We measured the effect of high-frequency stimulation of the subthalamic nucleus in two unilaterally MPTP-treated monkeys in order to determine whether it was possible to obtain reversible, gradual and controllable functional impairment of this structure. Clinical, mechanographic and electromyographic results demonstrate that this technique can alleviate parkinsonian rigidity and bradykinesia without causing dyskinesia or hemiballismus. This study supports the hypothesis that the subthalamic nucleus and its excitatory projections have an important role in the mechanisms sustaining the expression of parkinsonian motor changes, and suggests that high-frequency stimulation of the subthalamic nucleus could be included in treatment for parkinsonism.

A case of progressive encephalomyelitis with rigidity and positive antiglutamic acid decarboxylase antibodies [corrected]

A 50 year old woman developed progressive encephalomyelitis with rigidity over a three year period. Her CSF contained oligoclonal bands and both her serum and CSF contained antibodies directed against GABA-ergic synapses (antiglutamic acid decarboxylase [corrected] antibodies). These antibodies have recently been described in cases of stiff man syndrome. Both disorders may be part of a clinical spectrum that has an underlying autoimmune basis.

[Syndrome of the superior oblique muscle rigidity: clinico-anatomical aspects and results of treatment of 8 patients]

Tenectomy of the superior oblique muscle resulted in complete disappearance of Brown's syndrome in 7 out of 8 children operated on. In view of this, it can be a method of choice in treatment of the syndrome. There was the first clinical case of an additional abnormal attachment of the superior oblique muscle tendon to the sclera. In another patient an abnormal marked vascularization of the tendon identified histologically had the appearance of a muscular structure at the site of the tendon seen at the operation.

Drug effects on active immobility responses: what they tell us about neurotransmitter systems and motor functions

The literature reviewed indicates that active immobility can be promoted by systemic injections of various neurotransmitter systems, as follows: (1) Dopaminergic blockade of both D1 and D2 receptor subtypes. (2) Cholinergic agonism of both muscarinic and nicotinic receptors. (3) Noradrenergic agonism of both alpha-1 and alpha-2 receptors (but these agonists may interfere with haloperidol- and reserpine-induced catalepsy). (4) GABA agonism. (5) Histamine agonism, particularly at the H1 receptor. (6) Opiate agonism, including action of many endogenous opiate peptides, particularly those affecting mu and delta receptors. (7) Agonism by certain other peptides (neurotensin, cholecystokinin). Among the major interactions of neurotransmitter systems that regulate immobility, are the following: (1) Cholinergic-dopaminergic (cholinolytics disrupt catalepsy of dopaminergic blockade and dopaminergic agonists tend to disrupt cholinomimetic catalepsy). (2) Opiate-induced catalepsy is antagonized by the dopamine agonist, apomorphine, but is enhanced by amphetamine. It is also antagonized by certain alpha-2 adrenergic agonists, while it does not seem to be antagonized by anticholinergics. (3) Numerous other interactions have been reported, involving opiates and MSH, serotonin and dopamine mimetics, serotonin and ketamine, GABA and neuroleptics, neurotensin and anticholinergics and histamine. The significance of the multiple neurotransmitter systems is unknown. One possible explanation is that the various neurotransmitter systems participate in mediating the sensory inputs that are involved in triggering immobility and regulate the higher-order limbic and basal ganglia processing reactions that engage a final motor output pathway from the brainstem. The brain is assumed to contain two sets of systems, each with its own, or possibly overlapping, set of neurotransmitter systems, that promote either active immobility or locomotion. The systems reciprocally inhibit each other. Another view, not mutually exclusive, is that output from the locomotor-promoting system provides a negative feedback, via the active immobility pathways, to act as a "brake" on movement, while at the same time maintaining the muscular tonus that is characteristic of active immobility.

The effects of treatment on masticatory muscle activity and mandibular posture in myofascial pain-dysfunction patients

The purpose of this study was to evaluate tonic masticatory muscle activity and the postural rest position of the mandible, pre- and post-treatment, in patients with TM disorders. Forty-one patients diagnosed as suffering from myofascial pain-dysfunction (MPD) were evaluated, with electromyography (EMG) used to measure the muscle activity of the masseteric and anterior temporal areas at rest. Postural rest position was assessed by measurement of interocclusal distance. Twenty-three asymptomatic subjects were also tested as controls. Treatment for the pain group emphasized cognitive awareness of dysfunctional orofacial behavior and biofeedback training of the masseteric area to teach masticatory muscle relaxation. The pre-treatment EMG values of both the masseteric and anterior temporal areas were significantly higher for the pain group than for the control group. Post-hoc division of the pain group into successful and unsuccessful subgroups was made on the basis of the degree of symptom improvement. EMG activity decreased significantly in the masseters of both subgroups, but only the unsuccessful subgroup showed a significant decrease in anterior temporal activity following therapy. Interocclusal distance was significantly increased in both subgroups. These results suggest that tonic masticatory muscle activity may be elevated in MPD patients. They also suggest that a decrease in EMG activity in the masseter and anterior temporalis muscles and an opening of the postural rest position of the mandible may accompany completion of psychophysiological therapy, but these changes do not correspond directly with the outcome of that therapy.

Actin filament organization and myosin head labelling patterns in vertebrate skeletal muscles in the rigor and weak binding states

The structures of vertebrate skeletal muscles (particularly from frog and fish) in the rigor state are analysed in terms of the concept of target areas on actin filaments. Assuming that 100% of the heads are to be attached to actin in rigor, then satisfactory qualitative low-resolution modelling of observed X-ray diffraction data is obtained if the outer ends of these myosin heads can move axially (total range about 200A) and azimuthally (total range less than 60 degrees) from their original lattice sites on the myosin filament surface to attach in defined target areas on the actin filaments. On this basis, each actin target area comprises about four actin monomers along one of the two long-pitched helical strands of the actin filament (about 200 A) or an azimuthal range of actin binding sites of about 100 degrees around the thin filament axis. If myosin heads simply label in a non-specific way the nearest actin monomers to them, as could occur with non-specific transient attachment in a 'weak binding' state, then the predicted X-ray diffraction pattern would comprise layer lines at the same axial spacings (orders of 429 A) as those seen in patterns from resting muscle. It is shown that actin target areas in vertebrate skeletal muscles are probably arranged on an approximate 62 (right-handed) helix of pitch (P) of about 720 A, subunit translation P/6 and near repeat P/2. Troponin position need not be considered in defining the labelling pattern of cross-bridges on this 62 helix of target areas; the target areas appear to be defined solely by the azimuthal position of the actin binding sites. The distribution of actin filament labelling patterns could be regular in fish muscle which has a 'crystalline' A-band, but will be irregular in higher vertebrate muscles such as frog sartorius muscle.

Malignant hyperthermia in a black adolescent. A case report

Malignant hyperthermia is a rare genetic abnormality which presents in the peri-anaesthetic period with tachycardia, hyperventilation, hyperthermia and acidosis. Untreated, the mortality rate is in excess of 80%. This syndrome is much less common in blacks than whites. A case of malignant hyperthermia in a black South African, in whom the reaction only became evident in the postoperative period, is reported. The case also presents several other unusual features.

[Thermoelastic properties of cross-bridges in skinned skeletal muscle fibers of the frog under a condition of rigor]

Thermoelastic properties of cross-bridges were measured by application of small sinusoidal length perfurbations and submillisecond Joulean temperature jump to chemically skinned muscle fibre removed from rigor solution. The thermal expansion coefficient of fibres was 4.2 +/- 1.0 X 10(-5) K-1. We have observed neither rubber-like stiffness increase, nor tension increase and stiffness decrease (which are expected if alpha-coil melting occurs) after temperature jump.

[Interferon in chronic polyarthritis. Positive effect in clinical evaluation]

During the last two years, 80 patients with definite chronic rheumatoid arthritis were treated with interferon-gamma. Considerable improvement in the clinical picture occurred in 58, with pain decreasing rapidly and lastingly or even disappearing. Even in largely immobile patients the ability to walk and general mobility were nearly fully restored. The treatment was well tolerated in 74 patients. As the substance is administered subcutaneously it is suitable for out-patient treatment.

The effect of the ATP analogue AMPPNP on the structure of crossbridges in vertebrate skeletal muscles: X-ray diffraction and mechanical studies

Adenylylimidodiphosphate (AMPPNP), a nonhydrolysable analogue of ATP, has been used to arrest the crossbridge cycle of muscular contraction in one of its hypothetical intermediate states. Whole frog sartorius muscles were chemically demembranated, and it was found possible to cycle such skinned muscles reversibly between the relaxed and rigor states. The effect of binding of AMPPNP on the structure and spatial arrangement of the crossbridges of such muscles was studied using low-angle X-ray diffraction, with simultaneous recording of the mechanical effects, starting from the rigor state. Saturating concentrations of MgAMPPNP produce a characteristic decrease of about 50% in the original rigor isometric tension with a concomitant increase in muscle length by 0.13%. The equatorial X-ray diffraction pattern is modified in the following way: the lattice dimensions and the intensity of the (10) equatorial reflection do not change, while the intensity of the (11) equatorial reflection increases slightly. These observations of very small equatorial changes could be explained by assuming that in these muscles (as distinct from others such as rabbit psoas) the analogue does not produce a significant degree of detachment of crossbridges; that is, there are only AMPPNP-modified attached ones. The changes in the meridional X-ray diffraction pattern are more pronounced: the meridional reflection at 14.5 nm decreases in intensity, and the meridional reflection at 7.2 nm increases considerably: the intensity of all the actin-based off-meridional layer-lines decreases. There are no signs of the characteristic relaxed layer-lines, and the changes in the layer-line intensities are probably due to there being a single population of AMPPNP-modified attached crossbridges, rather than a mixture of attached and detached crossbridges. Thus the AMPPNP X-ray pattern, both equatorially and meridionally, is somewhat similar to the rigor one, indicating that most of the crossbridges remain attached. On the other hand, the fact that there are some changes in the layer-line intensities of the AMPPNP frog pattern, without the appearance of any signs of a relaxed equatorial pattern, indicates that the attached crossbridges are in a structural state that is different from rigor, one is not seeing, apparently, simply a mixture of rigor and relaxed states. Our tentative interpretation of this result is that there may be a structural change in the crossbridge near to the junction with S2, with less significant changes occurring in the parts of the crossbridge close to actin.

The process of muscle relaxation by the combined action of MgAMPPNP and ethylene glycol

Insect flight muscle fibres were relaxed by the combined action of MgAMPPNP and ethylene glycol, as measured by the stiffness of the fibres. Relaxation occurred over a small range of glycol concentration. Addition of Ca2+ raised the glycol required for relaxation. The speed at which the stiffness measurement was made did not influence the glycol concentration at which relaxation occurred. Glycol in excess of that needed to relax the muscle caused a slight rise in high-frequency stiffness. Removal of the glycol restored the rigor stiffness. Under glycol-relaxed conditions, much of the AMPPNP bound in muscle fibres was retained during cold-chase (elution of [3H] AMPPNP by nonradioactive AMPPNP); the intensity ratio of the inner equatorial X-ray diffraction peaks rose upon glycol relaxation to a value slightly below that characteristic of natural relaxation. The results are interpreted in terms of cooperative attachment of the crossbridges to actin.

The frequency of physical signs usually attributed to meningeal irritation in elderly patients

Nuchal rigidity, which may be a sign of meningitis, was found in 35 per cent of geriatric patients on acute-care and rehabilitation wards and in 13 per cent of younger patients on an acute-care ward. It was significantly associated with cerebrovascular disease, confusion, abnormal plantar responses, and primitive reflexes. Elderly patients who have nuchal rigidity with no history of neurologic or cognitive disorders should be investigated for meningitis.

Decerebrate rigidity in animals

Decerebrate rigidity (DR) in animals is caused by a release of spinal neurons from supraspinal inhibition, which results in a caricature of reflex standing and includes tonic neck and labyrinthine reflexes. The reticular formation, cerebellum, vestibular complex, spinal cord, and muscle spindle system and their neurophysiological interaction are critical to DR. Its discovery and investigation were essential to Sherrington's concept of the integrative action of the nervous system. There are two types of DR with different anatomical and physiological bases. Intercollicular decerebration yields rigidity in extensor muscles that results from bilateral destruction of the central tegmental tracts, is abolished by posterior root section, and is due to a facilitation of gamma motoneuron discharge (gamma animal). Anemic decerebration is characterized by excessive extensor rigidity, depends upon the release of tonic labryinthine reflexes from cerebellar inhibition, is independent of posterior root section, and is caused by excessive alpha motoneuron discharge (alpha animal). DR has provided an insight into the mechanisms of posture and standing, but the correlation of laboratory observations and results from animals to humans must be made with caution.

The effect of regional myocardial ischemia on series elastic and contractile elements of glycerinated heart muscle in dogs

The response of the contractile and the series elastic elements to ischemia was studied with isometric contraction and quick release methods after measuring the passive length-tension relationship in glycerinated heart muscle fibers of dogs at resting state. Myocardial infarction was induced by ligating left coronary artery. Muscle fibers taken from the ischemic area three hours after ligation demonstrated reduction in maximal developed tension (P0), the maximal rate of tension development (dp/dtmax) and Vmax. The time to peak tension (t0) was increased. As in fresh papillary muscle the modulus of elasticity of active glycerinated muscle increased in proportion to load. The stiffness of the series elastic element elevated significantly in ischemic muscle fibers. The passive stiffness in resting state showed a decrease in the slope accompanied by an increase in the intercept in ischemic heart muscle. Therefore, increased stiffness of the series elastic element and diminished contractility are present following acute myocardial infarction.

Polarization of tryptophan fluorescence measurements in muscle. A re-evaluation

The degree of polarization of the intrinsic tryptophan fluorscence of glycerinated simgle muscle fibres or fibre bundles (rabbit psoas or dorsal longitudinal muscle of Lethocerus maximus) was measured: a) With sufficiently high (15 mM) ATP concentration or when an ATP regenerating system was used no difference in the degree of polarization of a contracting and a relaxed muscle was detected, whereas a distinct difference was detected between the relaxed and the rigor state. In contrast a distinct difference between the relaxed and contracting state was obtained at low ATP concentrations (5 mM). This difference is interpreted to be caused by an ATP-free core (rigor core) in the centre of the fibre. b) No change in the polarization degree was detected after a rapid release of the contracting muscle. c) In rigor state no difference in the degree of polarization of the tryptophan fluorescence was observed in the presence or absence of AMPPNP (concentration 0.5 mM). These findings and the lack of difference between the polarization degree of the contracting and the relaxed muscle is interpreted to indicate that the polarization degree of the tryptophan fluorescence is not sensitive to the orientation of the cross bridges, or that the cross bridges do not rotate.

Studies on structural changes of F-actin and myosin in living, intact and damaged muscle fibres by means of polarized ultraviolet fluorescence microscopy

By means of polarized ultraviolet fluorescence microscopy the structural changes of F-actin and myosin were discovered at the changing a functional state of a living muscle fibre and during spreading degeneration (Zenker's necrosis). The character of conformational changes of F-actin and myosin at activation, contraction, contracture and rigor is similar, but the number of changed macromolecules depends on a fibre state. At fibre local damage in its morphological intact parts there was found an alternation of zones, reflecting two states unusual for a fibre. During spreading degeneration these states transform into irreversible contracture and then into rigor. Similar changes were observed in muscle fibres obtained from denervated muscles.

Increased dynamic stiffness of trabeculae carneae from senescent rats

Dynamic stiffness was measured in both adult and senescent Wistar rats using sinusoidal length perturbations from 17 to 40 Hz, superimposed on isometric contractions at low and below Lmax. The slope of the stiffness-tension relationship was found to be increased in senescent muscles of both sexes and at two different temperatures. The age dependence of the slope was independent of resting muscle length. The slope also exhibited frequency dependence and hysteresis that indicates the presence of viscoelasticity during activation. No age dependence was seen in peak active tension, peak dT/dt, or resting stiffness. The findings of this study, taken together with other studies that have shown a decreased shortening ability in the senescent muscle, explain in part the maintenance of active tension development in the face of decreased shortening ability associated with the senescent muscle.