Proteoglycans Of Intervertebral Disc Research Articles

DI-5-Cuffs: Lumbar Intervertebral Disc Proteoglycan and Water Content Changes in Humans after Five Days of Dry Immersion to Simulate Microgravity.

Most astronauts experience back pain after spaceflight, primarily located in the lumbar region. Intervertebral disc herniations have been observed after real and simulated microgravity. Spinal deconditioning after exposure to microgravity has been described, but the underlying mechanisms are not well understood. The dry immersion (DI) model of microgravity was used with eighteen male volunteers. Half of the participants wore thigh cuffs as a potential countermeasure. The spinal changes and intervertebral disc (IVD) content changes were investigated using magnetic resonance imaging (MRI) analyses with T1-T2 mapping sequences. IVD water content was estimated by the apparent diffusion coefficient (ADC), with proteoglycan content measured using MRI T1-mapping sequences centered in the nucleus pulposus. The use of thigh cuffs had no effect on any of the spinal variables measured. There was significant spinal lengthening for all of the subjects. The ADC and IVD proteoglycan content both increased significantly with DI (7.34 ± 2.23% and 10.09 ± 1.39%, respectively; mean ± standard deviation), p < 0.05). The ADC changes suggest dynamic and rapid water diffusion inside IVDs, linked to gravitational unloading. Further investigation is needed to determine whether similar changes occur in the cervical IVDs. A better understanding of the mechanisms involved in spinal deconditioning with spaceflight would assist in the development of alternative countermeasures to prevent IVD herniation.

Effects of Training and Overtraining on Intervertebral Disc Proteoglycans.

Animal experimental study. Evaluate the effect of physical activity and overtraining condition on glycosaminoglycan concentration on the intervertebral disc (IVD) using a rat running model. Some guidelines recommend the implementation of a physical exercise program as treatment for low back pain; however, cyclic loading impact on the health of the IVD and whether there is a dose-response relationship is still incompletely understood. Thirty-two rats ages 8 weeks were divided into four groups with eight animals each. The first 8 weeks were the adaptive phase, the overtraining phase was from the ninth to the eleventh week, which consisted of increasing the number of daily training sessions from 1 to 4 and the recovery phase was represented by the 12th and 13th weeks without training. Control group 1 (CG1) did not undergo any kind of training. Control group 2 (CG2) completed just the adaptive phase. Overtraining group 1 (OT1) completed the overtraining phase. Overtraining group 2 (OT2) completed the recovery phase. Running performance tests were used to assess the "overtraining" status of the animals. IVD glycosaminoglycans were extracted and quantified, and identified by electrophoresis. Glycosaminoglycans showed a distribution between chondroitin sulfate and dermatan sulfate. Glycosaminoglycans quantification showed decreasing concentration at the following order: OT1 > CG2 > OT2 > CG1. Increased expression of dermatan sulfate was verified at the groups submitted to any training. Overtraining condition, as assessed by muscle and cardiovascular endurance did not lessen glycosaminoglycan concentration in the IVD. In fact, physical exercise increased glycosaminoglycan concentration in the IVD in proportion to the training load, even at overtraining condition, returning to normal levels after the recovery phase and glycosaminoglycan production is a reversible acute positive response for mechanical stimulation of the IVD. N/A.

Effect of in uteroexposure to diethylstilbestrol on lumbar and femoral bone, articular cartilage, and the intervertebral disc in male and female adult mice progeny with and without swimming exercise

IntroductionDevelopmental exposure to estrogens has been shown to affect the musculoskeletal system. Furthermore, recent studies have shown that environmental exposure to estrogen-like compounds is much higher than originally anticipated. The aim of this study was to determine the effects of diethylstilbestrol (DES), a well-known estrogen agonist, on articular cartilage, intervertebral disc (IVD), and bone phenotype.MethodsC57Bl/6 pregnant mice were dosed orally with vehicle (peanut oil) or 0.1, 1.0, and 10 μg/kg/day of DES on gestational days 11 to 14. Male and female pups were allowed to mature without further treatment until 3 months of age, when swim and sedentary groups were formed. After euthanasia, bone mineral density (BMD), bone mineral content (BMC), bone area (BA), and trabecular bone area (TBA) of the lumbar vertebrae and femur were measured by using a PIXImus Bone Densitometer System. Intervertebral disc proteoglycan was measured with the DMMB assay. Histologic analysis of proteoglycan for IVD and articular cartilage was performed with safranin O staining, and degeneration parameters were scored.ResultsThe lumbar BMC was significantly increased in female swimmers at both the highest and lowest dose of DES, whereas the femoral BMC was increased only at the highest. The males, conversely, showed a decreased BMC at the highest dose of DES for both lumbar and femoral bone. The female swim group had an increased BA at the highest dose of DES, whereas the male counterpart showed a decreased BA for femoral bone. The TBA showed a similar pattern. Proteoglycan analysis of lumbar IVDs showed a decrease at the lowest doses but a significant increase at the highest doses for both males and females. Histologic examination showed morphologic changes of the IVD and articular cartilage for all doses of DES.ConclusionsDES significantly affected the musculoskeletal system of adult mice. Results suggest that environmental estrogen contaminants can have a detrimental effect on the developmental lumbar bone growth and mineralization in mice. Further studies measuring the impact of environmental estrogen mimics, such as bisphenol A, are then warranted.

Point of View: Changes in Proteoglycans of Intervertebral Disc in Diabetic Patients

Point of View: Changes in Proteoglycans of Intervertebral Disc in Diabetic Patients

Changes in proteoglycans of intervertebral disc in diabetic patients. A possible cause of increased back pain.

Characterization of the analytic profile of proteoglycans in the intervertebral discs at L4-L5 of nondiabetic (n = 5) and diabetic (n = 5) age-matched subjects. The discs used were discarded material from operations. To clarify the reason for the higher risk of disc prolapse in diabetic patients. The pathogenesis of diabetes results from a combination of neurologic dysfunctions and a yet undefined metabolic failure, which leads to an abnormal proteoglycan profile. The following methods were used to determine the proteoglycan profile: the measurement of 35S-sulfate uptake per gram wet tissue into sulfated glycosaminoglycan using fresh tissue explants; extraction of proteoglycans by 4 M guanidinium chloride containing protease inhibitors, with further purification by ultracentrifugation on cesium chloride buoyant density gradient under dissociative conditions; total uronic acid and protein contents in the various gradient fractions; assessing the length of sugar side chains of isolated 35Sulfate-glycosaminoglycan molecules by separation of the glycosaminoglycan molecules on a Sepharose 6B-CL column; and paper chromatography of the final digest products of glycosaminoglycan molecules obtained by chondroitinase ABC, a glycosaminoglycan-degrading enzyme. The findings show that discs from normal nondiabetic subjects have 15 times the rate of 35Sulfate incorporation into glycosaminoglycan molecules than do discs of diabetic patients. The proteoglycans of diabetic patients are banded at a lower buoyant density, indicating a lowered glycosylation rate and a lower number of sugar side chains per core protein. In discs of diabetic patients, there is a slight increase in the chain length of chondroitin sulfate. Further analysis of the glycosaminoglycan chains showed a decreased amount of keratan sulfate, compared with that in nondiabetic subjects. However, the total uronic acid content of the disc tissues and the ratio of uronic acid to protein of each fraction were unchanged in diabetic patients versus that in control subjects. Discs in patients with diabetes have proteoglycans with lower buoyant density and substantially undersulfated glycosaminoglycan, which with the specific neurologic damage in these patients, might lead to increased susceptibility to disc prolapse.

A Comparative Study of the Composition of Discs and of Proteoglycans from Different Spinal Levels of Sheep

SummaryCompositional analyses were undertaken on lumbar (L2L3 - L5L6) and lumbosacral (L6S1) intervertebral disc tissues from young adult (2-year-old) merino wethers. The proteoglycan level in the nucleus pulposus of the lumbosacral disc was significantly lower than that found in the nucleus pulposus of lumbar levels (p&lt;0.05). The annulus fibrosus was richer in collagen compared to the nucleus pulposus in all discs examined, and the lumbosacral disc consistently had both higher annulus fibrosus and nucleus pulposus collagen levels than lumbar discs (p&lt;0.05). Aggregation of the high buoyant density proteoglycans, with hyaluronic acid, was generally higher in annulus fibrosus proteogly-cans than nucleus pulposus proteogly-cans irrespective of the spinal level examined. Examination of the inter-vertebral disc proteoglycans, by composite agarose polyacrylamide gel electrophoresis, demonstrated three proteoglycan subpopulations and that the nucleus pulposus generally contained a greater proportion of higher mobility more polydisperse proteoglycan species than the annulus fibrosus.Ovine intervertebral disc collagen and proteoglycan composition varies with spinal level. Lumbosacral intervertebral discs contain greater levels of non-aggregatable more polydisperse proteoglycan species than lumbar discs, which may reflect their relative proximities to the pelvis and the variable levels of stress experienced by the respective tissues.

Proteoglycans in the intervertebral disc of young dogs following strenuous running exercise.

The proteoglycans (PGs) of intervertebral disc were studied in ten beagles which ran on a treadmill for one year (up to 40 km/day) and in ten non-running control dogs. Nucleus pulposus and annulus fibrosus from cervical (C5) and thoracic (T6 and T12) discs were labeled in vitro with 35SO4. The extractability, concentration and synthesis of PGs, and the electrophoretic subpopulations, aggregation and glycosaminoglycan chain lengths of newly-synthesized and total PGs were measured. Sulfate incorporation was significantly elevated by running in the C5 disc and reduced in the annulus of T6 discs. In the annulus of the T6 discs the concentration of total PGs was significantly lower although that of dermatan sulfate PGs was actually higher than in the controls. The results show that enhanced loading of the spine exerts significant alterations in the intervertebral disc PGs in a spine-level specific manner. In the most strained area of the spine (upper thoracic), the alterations in the runners suggest compromised biomechanical properties of the disc.

A Comparison of the High Buoyant Density Proteoglycans Isolated from the Intervertebral Discs of Chondrodystrophoid and Non-Chondrodystrophoid Dogs

Groups of purebred beagles and greyhounds of similar ages (1.5–2.5 years) were used for the study. Intervertebral disc proteoglycans (PGs) were radiolabelled in vivo (with [35Sol-J, 24 hours and 60 days prior to euthanasia, when lumbar discs were dissected into nucleus pulposus (NP) and annulus fibrosus (AF). Aliquots of each disc region were separately analysed for total PG content as hexuronate. The remaining tissue was subjected to extraction with 4.0 M GuHCl. High buoyant density PGs were isolated from these extracts by CsCl density gradient ultracentrifugation. The hydrodynamic size and aggregatability of the 24-hour, 60-day-old, and resident PG populations were determined by Sepharose CL2B chromatography in the presence or absence of excess hyaluronic acid. While the hydrodynamic sizes of the newly synthesized (24-hour) disc PG preparations appeared to be similar, the 60-day-old greyhound disc PGs were found to be larger than the corresponding beagle disc PG populations. However, the keratan sulphate-core protein complexes prepared by chondroitinase ABC digestion of the newly synthesized (24 hour) disc PGs showed that the greyhound disc preparations were also larger than those from beagle discs. Approximately 80% of the newly synthesized PGs from beagle and greyhound discs were capable of aggregating with hyaluronic acid, however, this was reduced to 55% for the 60 day-old PGs in NP and AF and even less for the resident PG populations (as determined by hexuronate analysis). Significantly, PG aggregation was lower in the greyhound NP and AF preparations than in the corresponding PGs isolated from the beagle disc. These data suggest distinct differences in the turnover of PGs in the discs of these canine breeds.

Articular cartilage and intervertebral disc proteoglycans differ in structure: an electron microscopic study.

Articular cartilage and the intervertebral disc tissues have different material and biological properties and different patterns of aging and degeneration. To determine if the proteoglycans of these tissues differ in structure, we used the electron microscopic monolayer technique to compare baboon articular cartilage proteoglycans with baboon annulus fibrosus, transition zone, and nucleus pulposus proteoglycans. Intervertebral disc and articular cartilage proteoglycans differed significantly. Articular cartilage contained large proteoglycan aggregates formed from hyaluronic acid central filaments, multiple monomers, and large nonaggregated monomers. These molecules were identical to those of nasal cartilage, growth plate cartilage, chondrosarcomas, or menisci. In contrast, the intervertebral disc tissues contained only nonaggregated proteoglycan monomers and clusters of monomers without apparent central filaments. Intervertebral disc nonaggregated monomers were shorter and more variable in length than those from articular cartilage, and nucleus pulposus nonaggregated monomers were even shorter and more variable in length than transition zone and annulus fibrosus monomers. These observations suggest that significant differences in proteoglycan metabolism exist between articular cartilage and intervertebral disc.

Chymopapain, chemonucleolysis, and nucleus pulposus regeneration. A biochemical and biomechanical study.

In the adult mongrel dog, in vivo injection of chymopapain into the intervertebral disc resulted, at two weeks, in disc space narrowing. However, [35S]sulfate labeling and proteoglycan characterization demonstrate that the nucleus retains the ability to synthesize proteoglycans, although they were degraded rapidly by residual proteolytic activity. Three months following chymopapain treatment, the intervertebral dog disc shows that an increase in disc height, return of nuclear material, and proteoglycan aggregate is present. At six months following chymopapain treatment, proteoglycans of similar characteristics to normal canine intervertebral disc are identified with a glucosamine/galactosamine ratio approaching normal values. Biomechanically, the short-term (30-120 minutes) in vitro effects of chymopapain appear to be the same as the carrier causing increased disc height, stiffness values, and creep rates. In the vivo study, after three weeks, chymopapain-injected discs had significant reductions in disc height and compressive stiffness, but the creep rate was increased substantially. However, at three months postinjection, these biomechanical properties began to reverse and approached those of the uninjected controls. The observations reported in this study suggest that chymopapain has a profound but reversible effect on normal canine intervertebral disc. The radiographic narrowing of the intervertebral disc following chymopapain injection correlates with loss of proteoglycan content, structure, and biomechanical properties. The restoration of normal disc height following chymopapain injection is explained by reconstitution of normal intervertebral disc. EDTA and cysteine used alone have no discernable in vivo enzymatic effect on intervertebral disc proteoglycan biochemistry. Chemonucleolysis with chymopapain would appear less likely to alter permanently proteoglycan biochemistry and the biomechanical properties of the disc than surgical excision in experimental animals.