Biomechanical Effect of Macroscopic Degeneration in a Lumbar Intervertebral Disc

2008 ◽  
Author(s):  
Raghu N. Natarajan ◽  
Hannah Lundberg ◽  
Howard An ◽  
Gunnar B. Andersson
Keyword(s):  
Animal Studies ◽  
Structural Integrity ◽  
Progressive Failure ◽  
Tissue Structure ◽  
Lumbar Intervertebral Disc ◽  
Structural Alterations ◽  
Disc Tissue ◽  
Age Related ◽  
Biomechanical Effect ◽  
Age Related Changes

Structural alterations of the disc are accompanied by changes in disc tissue structure and composition during degeneration processes. Fissures and cracks appear in the disc some times extending from the outer annulus to the nucleus. Animal studies have shown that when a rim lesion was introduced in the annulus, progressive failure on the inner annulus was observed (1). From a macroscopic study on lumbar motion segments originating from regular autopsies it was shown (2) that nuclear clefts precede annular tears. Within the annular tears, rim lesions follow the radial and concentric tears. These age-related changes in disc tissue decrease the structural integrity of the disc contributing to the progression of degeneration. The effect of existing cracks and fissures in the lumbar discs on the biomechanics of the disc is an area where there is very little information currently in the literature.

Presbyacusis and the Auditory Brainstem Response

2002 ◽  
Vol 45 (6) ◽  
pp. 1249-1261 ◽  
Author(s):  
Flint A. Boettcher
Keyword(s):  
Hearing Loss ◽  
Auditory System ◽  
Auditory Brainstem Response ◽  
Animal Studies ◽  
Auditory Brainstem ◽  
Clinical Tool ◽  
Age Related ◽  
Brainstem Response ◽  
Auditory Functions ◽  
Age Related Changes

Age-related hearing loss (ARHL or presbyacusis) is an increasingly common form of sensorineural hearing loss (SNHL) as a result of changing demographics, and the auditory brainstem response (ABR) is a common experimental and clinical tool in audiology and neurology. Some of the changes that occur in the aging auditory system may significantly influence the interpretation of the ABR in comparison to the ABRs of younger adults. The approach of this review will be to integrate physiological and histopathological data from human and animal studies to provide a better understanding of the array of age-related changes in the ABR and to determine how age-related changes in the auditory system may influence how the ABR should be interpreted in presbyacusis. Data will be described in terms of thresholds, latencies, and amplitudes, as well as more complex auditory functions such as masking and temporal processing. Included in the review of data will be an attempt to differentiate between age-related effects that may strictly be due to threshold elevation from those that may be due to the aging process.

scholarly journals Age-related changes in human cervical, thoracal and lumbar intervertebral disc exhibit a strong intra-individual correlation

2011 ◽  
Vol 21 (S6) ◽  
pp. 810-818 ◽  
Author(s):  
C. Weiler ◽  
M. Schietzsch ◽  
T. Kirchner ◽  
A. G. Nerlich ◽  
N. Boos ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Lumbar Intervertebral Disc ◽  
Age Related ◽  
Age Related Changes

Effect of Annular Micro Tear on Lumbar Intervertebral Disc Biomechanics

2010 ◽  
Author(s):  
Raghu N. Natarajan ◽  
Mohammed Qasim ◽  
Howard An ◽  
Gunnar B. J. Andersson
Keyword(s):  
Intervertebral Disc ◽  
Tissue Structure ◽  
Age Group ◽  
Human Cadaver ◽  
Lumbar Intervertebral Disc ◽  
Structural Alterations ◽  
Disc Herniations ◽  
Probability Of Presence ◽  
Cadaver Studies ◽  
Annular Tear

Structural alterations of the disc are accompanied by changes in disc tissue structure and composition during degeneration processes. Human cadaver studies have shown that the probability of presence of annular tear is 0.6 in the age group 30 to 34 which increases to 0.85 in the 60 year age group. Among different phenomena that occur during disc degeneration, annular radial tears are commonly associated with disc herniations. The effect of increase in size of radial micro tear in the lumbar discs on the change in biomechanics of the disc is an area where there is very little information currently in the literature.

scholarly journals Animal aging and regulation of sympathetic nerve discharge

2010 ◽  
Vol 109 (4) ◽  
pp. 951-958 ◽  
Author(s):  
Michael J. Kenney
Keyword(s):  
Animal Models ◽  
Sympathetic Nerve ◽  
Animal Studies ◽  
Current Knowledge ◽  
Human Subjects ◽  
Sympathetic Nerves ◽  
Age Related ◽  
Current Knowledge Base ◽  
Age Related Changes ◽  
Nerve Discharge

Studies completed in human subjects have made seminal contributions to understanding the effects of age on sympathetic nervous system (SNS) regulation. Numerous experimental constraints limit the design of studies involving human subjects; therefore, completion of studies in animal models of aging would be expected to provide additional insight regarding mechanisms mediating age-related changes in sympathetic nerve discharge (SND) regulation. The present review assesses the current state of the literature regarding contributions from animal studies on the effects of advancing age on SND regulation, focusing primarily on studies that have used direct recordings of sympathetic nerve outflow. Few studies using direct SND recordings have been completed in animal models of aging, regardless of the fundamental component of SND regulation reviewed (basal levels, acute responsiveness, relationships between the discharges in sympathetic nerves, central neural regulation). SNS responsiveness to various acute stressors is altered in aged compared with young animals; however, mechanisms remain virtually unexplored. There is a marked dearth of studies that have used central neural microinjection techniques in conjunction with SND recordings in aged animals, making it difficult to develop an evidence-based framework regarding potential age-associated effects on central regulation of SND. Determination of age-related changes in mechanisms regulating SND is important for understanding relationships between chronic disease development and changes in SNS function; however, this can only be achieved by substantially extending the current knowledge base regarding the effects of age on SND regulation in animal studies.

scholarly journals Age related changes in the primary somatosensory area of the cerebral cortex

2020 ◽  
Vol 11 (5) ◽  
pp. 87-92
Author(s):  
Santos George Joseph ◽  
Anne George
Keyword(s):  
Cerebral Cortex ◽  
Structural Integrity ◽  
Age Groups ◽  
Pyramidal Cells ◽  
Stellate Cells ◽  
Somatosensory Area ◽  
Age Related ◽  
Study Results ◽  
The Impact ◽  
Age Related Changes

Background: Age-related changes in structural and functional part of brain have been the motivation of previous and ongoing neuroscientific research. The focus of most studies done, were on different motor areas of the of the cerebral cortex. Very few studies were done on primary somatosensory areas of the brain. Aims and Objective: The aim of the study was to investigate the age-related changes in primary somatosensory area of the cerebral cortex of the human brain. Materials and Methods: The study was conducted on 50 autopsied brain specimens. The specimens removed were of both sexes belonging to various age groups ranging from 9 months to 75 years. The specimens were collected from the Department of Forensic Medicine, Medical College Kottayam. During the autopsy the meninges were carefully stripped off. The sulci and gyri were then examined carefully. Results: The depth of the upper area of the central sulcus is more than the middle and lower areas, both in the right and left halves of the cerebral cortex. The laminae of the primary somatosensory area have shown that as age advances there is a progressive increase in thickness except in the case of lamina IV. From the ages of 61 years onwards, laminar degeneration takes place. The thickest lamina was lamina V. The thinnest laminawas lamina IV. The stellate cells that dominate in lamina II and IV show a difference in their arrangement. In foetal life, the pyramidal cells were almost indistinguishable from the stellate cells. The pyramidal cells were seen mostly in lamina III and V. Conclusion: The study results suggest the possibility that in the more advanced stages of aging, the structural integrity of lamina IV is more consistent than other layers present in primary somatosensory area of the cerebral cortex. Further study is needed to examine the impact of ageing on somatosensory area.

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