safranine-t and Cadaver

Mechanical and biochemical analyses of cadaveric and surgically removed discs.. To test the hypothesis that fissures in the annulus of degenerated human discs are mechanically and chemically conducive to the ingrowth of nerves and blood vessels.. Discogenic back pain is closely associated with fissures in the annulus fibrosus, and with the ingrowth of nerves and blood vessels.. Three complementary studies were performed. First, 15 cadaveric discs that contained a major annulus fissure were subjected to 1 kN compression, while a miniature pressure transducer was pulled through the disc to obtain distributions of matrix compressive stress perpendicular to the fissure axis. Second, Safranin O staining was used to evaluate focal loss of proteoglycans from within annulus fissures in 25 surgically removed disc samples. Third, in 21 cadaveric discs, proteoglycans (sulfated glycosaminoglycans [sGAGs]) and water concentration were measured biochemically in disrupted regions of annulus containing 1 or more fissures, and in adjacent intact regions.. Reductions in compressive stress within annulus fissures averaged 36% to 46%, and could have been greater at the fissure axis. Stress reductions were greater in degenerated discs, and were inversely related to nucleus pressure (R(2) = 47%; P = 0.005). Safranin O stain intensity indicated that proteoglycan concentration was typically reduced by 40% at a distance of 600 μm from the fissure axis, and the width of the proteoglycan-depleted zone increased with age (P < 0.006; R(2) = 0.29) and with general proteoglycan loss (P < 0.001; R(2) = 0.32). Disrupted regions of annulus contained 36% to 54% less proteoglycans than adjacent intact regions from the same discs, although water content was reduced only slightly.. Annulus fissures provide a low-pressure microenvironment that allows focal proteoglycan loss, leaving a matrix that is conducive to nerve and blood vessel ingrowth.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Blood Vessels; Cadaver; Cell Movement; Child; Female; Humans; In Vitro Techniques; Intervertebral Disc; Intervertebral Disc Degeneration; Male; Middle Aged; Phenazines; Proteoglycans; Spinal Nerves; Stress, Mechanical; Young Adult

To use the ultrashort time-to-echo magnetic resonance imaging (UTE MRI) technique to quantify short T2* properties (obtained through gradient echo) of a disc from the human temporomandibular joint (TMJ) and to corroborate regional T2* values with biomechanical properties and histologic appearance of the discal tissues.. A cadaveric human TMJ was sliced sagittally and imaged by conventional and UTE MRI techniques. The slices were then subjected to either biomechanical indentation testing or histologic evaluation, and linear regression was used for comparison to T2* maps obtained from UTE MRI data. Feasibility of in vivo UTE MRI was assessed in two human volunteers.. The UTE MRI technique of the specimens provided images of the TMJ disc with greater signal-to-noise ratio (~3 fold) and contrast against surrounding tissues than conventional techniques. Higher T2* values correlated with lower indentation stiffness (softer) and less collagen organization as indicated by polarized light microscopy. T2* values were also obtained from the volunteers.. UTE MRI facilitates quantitative characterization of TMJ discs, which may reflect structural and functional properties related to TMJ dysfunction.

Topics: Adult; Aged; Azo Compounds; Biomechanical Phenomena; Cadaver; Collagen; Coloring Agents; Elastic Modulus; Feasibility Studies; Humans; Image Enhancement; Image Processing, Computer-Assisted; Imaging, Three-Dimensional; Magnetic Resonance Imaging; Male; Microscopy, Polarization; Phenazines; Reference Standards; Rosaniline Dyes; Signal-To-Noise Ratio; Stress, Mechanical; Temporomandibular Joint Disc