Number Of Neural Elements Research Articles

Histological changes and neural elements in the subacromial bursa on patients with rotator cuff tear: Pilot study.

Objective:This study aimed to investigate the neural elements of the subacromial bursa (SAB) in rotator cuff tears.Materials and methods:Twenty patients with rotator cuff tears were recruited, and their visual analog scale (VAS) score, duration of symptoms, and range of motion (ROM), including flexion, external rotation, and internal rotation were evaluated. Tear size was measured using magnetic resonance imaging (MRI). The SAB specimens obtained during arthroscopic rotator cuff repair were studied using routine hematoxylin and eosin staining and immunohistochemistry (S-100 protein and PGP 9.5 protein). The SAB specimen for the control group was obtained from 2 fresh cadavers and 2 patients with acute humeral shaft fracture. The Mann-Whitney U test was applied to assess the difference between histological findings of the rotator cuff tear group and control group. The correlation between the histological findings and clinical features was evaluated using the Spearman correlation coefficient.Results:The mean duration of symptom was 10.2 ± 6.4 months. The preoperative average VAS score was 2.9 ± 1.2. The degrees of preoperative ROM in forward flexion and external and internal rotations were 143.8 ± 19.5, 49.5 ± 23.1, and –4.3 ± 4.2, respectively. The tear was 2.0 ± 0.9 cm. For histological findings, the number of neural elements per low power field in the rotator cuff tear group was significantly less than the control group in both immunohistochemical stainings (S-100: 0.5 ± 0.7 vs 2.8 ± 0.5, p < .01; PGP 9.5: 0.4 ± 0.7 vs 3.5 ± 0.6, p < .01). During the correlation analysis, the number of neural elements in the PGP 9.5 staining was negatively correlated with the ROM in forward flexion and external rotation.Conclusion:This study revealed that chronic rotator cuff tears may induce degeneration of neural elements in SAB.

Changes in the mechanisms of brain adaption during postnatal ontogeny of rats exposed to prenatal hypoxia

We have previously shown that acute hypoxia during embryogenesis impaired learning and memory processes during rat ontogeny [1]. These impairments could be related to changes in the structural and functional properties of neuronal networks of the cerebral cortex, specifically, with neurotransmission and structural intercellular interactions, because the number of neural elements in the hippocampus and the cerebral cortex in the adult rats that were exposed to hypoxia during embryogenesis were similar to the control values. It is known that impairments in cognitive functions and changes in amyloid precursor protein metabolism that are specific for the progress of dementia or Alzheimer’s disease are associated with a decrease in the expression of synaptophysine (a protein of presynaptic terminals) and the actin-associated spine protein synaptopodine [2]. A decrease in the expression of synaptopodine may result in disturbances of cytoskeleton formation in labile dendritic spines and a decrease in the plasticity of neuronal networks [3, 4]. The purpose of this study was comparative analysis of the synaptopodine distribution in the cortex and hippocampus during ontogeny in the control rats and the rats that had undergone prenatal hypoxia. On the basis of immunohistochemical data, we have demonstrated that prenatal exposure of rats to hypoxia leads to a decrease in the number of mobile synaptopodine-positive dendritic spines in the neuropile of cortical areas of the rat brain. These data demonstrate changes in the adaptive properties of neuronal networks and can explain disturbances in cognitive functions.

Neuronal regeneration after application of radiofrequency energy to collagenous tissue is affected by limb immobilization: an in vivo animal study

Despite widespread use of radiofrequency (RF)-shrinkage, there have been no studies on the influence of RF-energy on neural elements of collagenous tissue. The purpose of this study was to examine the effect of RF-shrinkage on neural structures of capsuloligamentous tissue and the recovery of neural elements under different postoperative treatment protocols. One patellar tendon of 46 New-Zealand-White rabbits was shrunk. Six rabbits were sacrificed immediately postoperative. Twenty rabbits were not immobilized, 10 were immobilized for 3 and 10 were immobilized for 6 weeks. A monoclonal antibody, specific against a neurofilament protein, was used to detect nerves and neural structures. Staining pattern of nerve fibres was significantly altered immediately postoperative. After 3 weeks the number of nerve fibres and bundles decreased significantly in immobilized and non-immobilized limbs. The loss of nerve fibres was significantly less in immobilized limbs. At 6 weeks the number of neural elements in immobilized limbs increased to the level of untreated control tissue. In non-immobilized limbs we found no recovery of neural elements 9 weeks postoperatively. At this time the number of nerve fibres and bundles was still significantly less compared to the untreated control limbs. RF-shrinkage causes significant alteration of neural elements. Under immobilization nerve fibres and bundles reach the level of normal untreated tissue. Careful rehabilitation is important after RF-shrinkage. Not only for biomechanical reasons, but also to allow the neural elements to recover, thermally modified tissue should be protected from normal physiologic loads.

Prediction of porosity and lithology in siliciclastic sedimentary rock using cascade neural assemblies

A novel approach to porosity and lithology prediction in siliciclastic sedimentary rocks is discussed here. It is based on the use of multi-element neural assembly with multiple inputs and a single output. In experiments with porosity prediction, the writers used one-, two- and three-dimensional input vector-parameters with coordinates (1) V p or V s; (2) V p and V s, and (3) petrophysical group index, V p and V s. When the neural assembly was trained to predict lithology, the input parameters were: (1) V p or V s; (2) V p and V s, and (3) V p, V s, and porosity. The writers utilized the training data-sets containing only 20 to 30 elements. To be able to work efficiently with such small training sets the writers used cascading neural assemblies specifically designed to work with small training data-sets. Each element of the neural assembly is a neural network of a simple structure. The elements of the assembly are combined in such a way that the approximation error of the assembly obtained during training session decreases with increasing number of elements. This allows for a simple and a well-defined methodology of estimating of a necessary number of neural elements in the assembly. The cost function of each element of neural assembly was taken as a sum of two terms. The first term was an estimate of the prediction error (a standard cost function of the predictive neural net), whereas the second term was a regularization term equal to the weighted sum of the squared norms of the transform matrixes. The neural network-based prediction of rock parameters was tested on a variety of training and test data-sets. Best results were achieved when the training data-set included representatives of all lithologies (petrophysical groups) contained in the test data-set and when the input parameters included independent data on the type of lithology or porosity in addition to seismic velocities.

Development of nerve fibres in the temporomandibular joint of the human fetus.

The development of nerve fibres in the temporomandibular joint (TMJ) in relation to the development of bone, muscle and fibre components was investigated in human fetuses ranging from 9 weeks of gestation to birth. Immunohistochemistry for the glia-associated protein S-100 and for the neuro-specific marker protein gene product 9.5 (PGP 9.5) were used; specimens were compared to specimens of adult TMJ capsule and disc. At 9-10 weeks, a small number of neural elements are already present in the connective tissue around the joint and in the mesenchyme between the two articular blastemas from which the disc will differentiate. By 19 weeks many nerve fibres are clearly visible. Immunohistochemical results suggest diffuse disc innervation extending along the entire disc but not in the thin central area. More complex structures, i.e. encapsulated corpuscles, were also seen. The fetal disc appears highly innervated compared to adult tissue; already at this developmental stage morphology and distribution of nerves and corpuscles in the joint capsule are comparable to those in the adult joint. It may be concluded that the innervation of the TMJ is detectable from the end of the second month and that it develops fully between the third and the fifth month of gestation. Nerve endings in the disc are most numerous at 20 weeks, after which a progressive reduction, possibly secondary to the growth of articular tissues, is observed throughout the last trimester of fetal life and into adult life. The innervation of the lateral pterygoid muscle, on the contrary, is much less than that seen in adult muscles, even at full-term.

Discrimination of Complex Electrical Stimulation Through a Multichannel Intracochlear Implant

A model has been developed to describe the electric fields generated in the inner ear when electrical stimuli are presented through a multichannel implant in the scala tympani of the cochlea. The model relies on the hypothesis that stimuli which excite the largest number of neural elements provide the greatest probability of successful discrimination by the implanted subject. It suggests that the effective stimulus is determined by the linear combination of electrical fields produced by the individual channels, and that excitation takes place in a spatially restricted area of the auditory nerve in the vicinity of the stimulating electrodes. The model was tested by biophysical measurements of the potential developed in the stimulated cochlea, and by a psychophysical study of the ability of a monkey to discriminate complex electrical signals using dual channel stimulation. The experimental findings are in agreement with the computer simulations.

Natural stimuli evoking somatosensory potentials.

NATURAL STIMULI EVOKING SOMATOSENSORY POTENTIALS A. Starr, H. Pratt,* and D. Burkef Department of Neurology University of California, Irvine Irvine, California 9271 7 The definition of somatosensory evoked potentials has customarily employed percutaneous electrical stimuli to activate mixed nerves, such as the median nerve a t the wrist, or sensory nerves, such as the digital nerves at the fingers. The use of a natural stimulus such as touch or pressure to evoke potentials has been utilized infrequently.’-’ An advantage of a natural stimulus is that it provides information as to the function of the receptor and its terminal nerve fibers whereas electrical stimulation of nerve trunks bypass these areas. Secondly, both the type of neural elements and the central pathways activated are relatively specific with a natural stimulus compared to electrical stimulation of nerve trunks. A major disadvantage of a natural stimulus is that complex procedures are often required for its quantification. Moreover, since natural stimuli usually activate a restricted number of neural elements, the amplitude of their evoked potentials may be less than those evoked by electrical stimulation. Over the past few years we habe had the opportunity to work on this problem and have utilized two types of natural stimuli: ( I ) mechanical deformation of the skin of the finger that feels like a tap,8-” and (2) flexion or extension of the ankle joint to activate muscle spindle receptors in the gastrocnemius or tibialis anterior muscle^.'^ These natural stimuli were capable of evoking potentials at several levels of the somatosensory pathway. Tactile stimuli elicit clear potentials at many levels of the somatosensory pathway but are of low amplitude compared to the potentials evoked by electrical stimulation of nerve trunks (FIGURE 1). Their scalp distributions are comparable” as are the effects of stimulus rate.“ Preliminary studies using tactile stimulation were completed in neonates and showed clear potentials at several levels of the pathway.’* However, cortical potentials could only be detected in 2 of 10 newborn infants compatible with a maturational delay in cortical circuits in youngsters of this age. Conduction times along the sensory pathway to natural tactile stimuli can be For instance, in calculated and used to assess abnormalities in clinical pop~lations.’~ an unpublished study of diabetic and uremic patients with peripheral neuropathy, we (Starr and Pratt) found the conduction time from mechanical stimulation of the index finger to the Occurrence of the evoked potentials recorded over the median nerve to be abnormal in 8 of 1 1 patients with uremia but normal in the 7 patients with diabetes. However, in both groups of patients proximal afferent conduction times between the wrist and axilla from electrical stimulation of the digital nerves were consistently abnormal (10/11 uremic patients; ti/7 diabetic patients). This finding would suggest *Present address: Gutwirth Bldg., Technion. Israel Institute of Technology, Haifa 32000, Israel. ?Present address: Unit of Clinical Neurophysiology, The Prince Henry Hospital, Little Bay, N.S.W. 2036 Australia. 0077-8923/S2/0388-0702 S1.75/0 Q 1982. NYAS