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

INTRODUCTION: Intervertebral disc (IVD) degeneration is characterized as a multifactorial disease, in which the hereditary background is thought to be of high importance. Accordingly, one would expect all spinal levels (lumbar/cervical/thoracal) to be affected by above-average disc degeneration in genetically predisposed individuals. The aim of this study, therefore, was to analyze the amount of degenerative changes in different spine levels in humans from different ages. MATERIALS AND METHODS: In detail, the presence, localization and abundance of histomorphological changes in the annulus fibrosus (AF) and nucleus pulposus (NP) in the cervical (C5/C6), thoracic (T2/T3) and lumbar (L2/L3) spine were investigated in complete autopsy IVD specimens (47 individuals) covering a complete age range (0-95 years). RESULTS: Results indicate that the highest degree of histo-degenerative changes were observed in the NP in all spine levels and showed an age-related expression pattern. With regard to the different spine levels, lumbar disc specimen showed significantly more degenerative changes compared to cervical and thoracic discs, whereas no statistical difference was observed between cervical and thoracic discs. In summary, highest grades of degeneration were observed in lumbar discs (especially in the NP). Intra-individual correlations between the degeneration score in the different levels showed a significant individual concordance. CONCLUSIONS: The intra-individual correlation of degenerative changes in all three examined spine regions further supports the notion that individual, i.e. genetic factors are strong predisposing factor for the development of age-related disc alterations.

Triptolide exhibits anti-inflammatory, anti-catabolic as well as anabolic effects and suppresses TLR expression and MAPK activity in IL-1ß treated human intervertebral disc cells.

INTRODUCTION: Increased levels of proinflammatory cytokines seem to play a pivotal role in the development of back pain in a subpopulation of patients with degenerative intervertebral disc (IVD) disease. As current treatment options are mostly limited to surgical interventions or conservative treatment, anti-inflammatory substances might offer a novel, more target-orientated therapeutic approach. Triptolide (TPL), a natural substance found in the Chinese medicinal herb Tripterygium wilfordii Hook, has been demonstrated to possess anti-inflammatory effects in various cells, but no studies exist so far for the IVD. Therefore, the aim of this study was to determine the effects of TPL on human IVD cells by analyzing changes in gene expression and underlying molecular mechanisms. MATERIALS AND METHODS: In order to investigate the anti-inflammatory, anabolic and anti-catabolic effect of TPL, dose-dependency experiments (n = 5) and time course experiments (n = 5) were performed on IL-1ß prestimulated human IVD cells and changes in gene expression of IL-6/-8, TNF-α, PGE2S, MMP1/2/3/13, aggrecan and collagen-I/-II were analyzed by real-time RT-PCR. The molecular mechanisms underlying the effects observed upon TPL treatment were investigated by analyzing involvement of Toll-like receptors TLR2/4 (real-time RT-PCR, n = 5), NF-κB, MAP kinases p38, ERK and JNK (immunoblotting and immunocytochemistry, n = 4) as well as RNA polymerase II (immunoblotting, n = 3). RESULTS: Results showed that 50 nM TPL exhibited an anti-inflammatory, anti-catabolic and anabolic effect on the mRNA level for IL-6/-8, PGE2S, MMP1/2/3/13, aggrecan, collagen-II and TLR2/4, with most pronounced changes after 18 h for proinflammatory cytokines and MMPs or 30 h for TLRs and matrix proteins. However, we also observed an up-regulation of TNF-α at higher concentrations. The effects of TPL did not seem to be mediated via an inhibition of NF-κB or a decrease of RNA polymerase II levels, but TPL influenced activity of MAP kinases p38 and ERK (but not JNK) and expression of TLR2/4. CONCLUSIONS: In conclusion, TPL may possess promising potential for the treatment of inflammation-related discogenic back pain in vitro, but its analgetic effect will need to be confirmed in an appropriate in vivo animal model.

Influence of extracellular osmolarity and mechanical stimulation on gene expression of intervertebral disc cells.

Intervertebral discs (IVD) have a higher extracellular osmolarity than most other tissues; moreover their osmolarity changes by around 25% during each diurnal cycle. In this study, changes in aggrecan, collagen I and collagen II expression of IVD cells were examined after exposure to osmotic environment alterations or mechanical stimulation under different osmotic conditions. Human and bovine IVD cells seeded in three-dimensional (3D) collagen type I matrices were cultured under hypo-osmotic (300 mOsm), iso-osmotic (400 mOsm), or hyperosmotic (500 mOsm) conditions. Osmolarity-induced changes in gene expression of IVD cells were measured after 5 days. Load-induced changes in gene expression under the different osmotic conditions were measured after application of hydrostatic pressure (0.25 MPa, 0.1 Hz, 30 min) or cyclic strain (4%, 1 Hz, 24 h). The results showed that IVD cells respond strongly to changes in the osmotic environment by altering mRNA expression. Human cells cultured over 5 days increased expression of aggrecan and collagen II in both nucleus and annulus cells under increasing osmolarity. In contrast, collagen I expression was inhibited at high osmolarity in both cell types. Mechanically induced alterations in gene expression appear to have only modest effects on matrix protein expression, but the same stimulus partly resulted in an inhibition or stimulation of gene expression, depending on the osmotic conditions. This study showed that the osmotic environment does not only have an appreciable effect on gene expression but also affects responses to mechanical stimuli. This suggests that the osmotic conditions cannot be ignored when examining physiological and pathological behavior of IVD cells.

Evaluation of porcelain surface treatments and agents for composite-to-porcelain repair.

Intraoral repairs often involve bonding composite to fractured porcelain. Newer adhesive systems, currently referred to as multipurpose systems, include materials with recommended procedures for repair of porcelain. This laboratory study evaluated various treatment regimens with the ProBond adhesive system. Three different porcelain surface procedures were used: (1) air abrasion with aluminum oxide (50 microm), (2) 8% hydrofluoric acid, and (3) air abrasion and hydrofluoric acid. Eight different treatment procedures were then used to bond 10 composite cylinders to porcelain surfaces in each group. Shear bond strengths (in megapascals) were determined with an Instron testing machine after storage in water for 24 hours at 37 degrees C and after 3 months of storage and thermocycling. The combination of air abrasion and hydrofluoric acid on porcelain surfaces before bonding composite recorded the most consistently effective bond strengths. Four of the treatment regimens in the air abrasion groups yielded low bond strengths at 3 months. This study also indicated that silane treatment of porcelain is critical for development of suitable bond strengths for composite.

Effects of thyroid hormone replacement on beta-adrenergic responsiveness of food-deprived rats.

Thyroid hormone levels and beta-adrenergic responsiveness after stimulation with the beta-adrenergic agonist isoproterenol were studied in four groups of male rats. The groups used were control rats, rats deprived of food for 72 h, rats administered 50 micrograms thyroxine (T4)/kg daily for 4 days, and rats deprived of food for 72 h and administered 50 micrograms T4/kg daily for 4 days. Food deprivation significantly decreased serum T4 and triiodothyronine (T3) levels, and administration of T4 significantly increased serum T4 and T3 levels in both fed and food-deprived rats. Administration of T4 led to lower body weights in both fed and food-deprived rats. Administration of isoproterenol led to increases in colonic and tail skin temperatures and heart rate. Food deprivation significantly attenuated the increased body temperatures and heart rate induced by isoproterenol, and administration of T4 to food-deprived rats returned these adrenergic responses to control levels. Administration of T4 to fed rats significantly increased the thermal and cardiac responses to isoproterenol above those of the control rats. Administration of isoproterenol also increased plasma glucose levels. Food deprivation significantly decreased both postsaline- and isoproterenol-stimulated glucose levels. However, administration of T4 was without effect on either the postsaline- or isoproterenol-stimulated glucose levels of either the fed or food-deprived rats. The decreases in T4 and T3 that accompany food deprivation may thus be responsible for some, but not all, of the reductions in beta-adrenergic responsiveness observed in food-deprived rats.