Age-related changes in the intercellular substance of human hyalin and collagen-fiber cartilage tissue

The articular cartilage of the hip joint and the intervertebral disks (LIV and LV), obtained from 42 corpses without any signs of pathology in these tissues, have been investigated. Six age groups have been distinguished: 21-30, 31-40, 41-50, 51-60, 61-70, 71 years of age and older. After the topo-optic reactions have been get, double refraction of glycosamineglycans (GAG) and collagen is studied in the structure and orientational regularity is estimated in these macromolecules in the matrix. The peculiarities on distribution of the collagenous fiber fasciculi in the intercellular substance in the hyalin and collagen-fibrillar cartilaginous tissue are demonstrated at the areas and depending on the age. Correlations in qualitative and quantitative changes of the GAG and collagen with age are analysed; this gives certain possibilities to reveal signs of similarity and difference in morphogenesis of hyalin and collagen-fibrillar cartilage tissue. Basing on the comparative analysis performed concerning the GAG and collagen state in the age aspect, as well as taking into account the data of previously performed investigations, the collagenous carcass can be characterized as the most stable component of the intercellular substance of cartilages, possessing a great reserve of strength. Homokinesis of the cartilaginous tissue is performed at the expense of the GAG; this ensures a high ability of the cartilaginous tissue to adaptation. A hypothesis on the GAG role in realization of adaptive rearrangements of the cartilaginous matrix at the macromolecular level is put forward.     

Structuro-functional organization of the fibrillar component and ground substance of human rib cartilage

A complex morphological investigation (histology, histochemistry, scanning and transmissive electron microscopy, electron histochemistry) has been performed to study the intercellular substance of the costal hyalinous cartilage. It has been demonstrated that the fibrillar framework of the costal cartilage consists of branching collagenous fibrillae, chaotically scattering. The fibrillae are surrounded with the ground substance; one of its components is the reticular ruthenium-positive structure.     

Biomechanical implications of degenerative joint disease in the apophyseal joints of human thoracic and lumbar vertebrae

An experimental technique for quantifying load-sharing in cadaveric spines is used to test the hypothesis that degenerative changes in human apophyseal joints are directly related to high levels of compressive load-bearing by these joints. About 36 cadaveric thoraco-lumbar motion segments aged 64-92 years were subjected to a compressive load of 1.5 kN. The distribution of compressive stress was measured in the intervertebral discs using a miniature pressure transducer, and stress measurements were summed over area to give the compressive force resisted by the disc. This was subtracted from the applied 1.5 kN to indicate compressive load-bearing by the apophyseal joints. The cartilage of each apophyseal joint surface was then graded for degree of degeneration. After maceration, each joint surface was scored for degenerative joint disease (DJD) affecting the bone. Results demonstrated that the apophyseal joints resisted 5-96% (mean 45%) of the applied compressive force. A significant positive correlation was demonstrated between age and cartilage degeneration, age and DJD bone score, apophyseal joint load-bearing and bone score, and cartilage score and load-bearing. The latter correlation was strongest for load-bearing above 50%. Ordinal regression showed that the variables describing bone DJD (marginal osteophytes, pitting, bony contour change, and eburnation) were significantly correlated with degree of cartilage degeneration. It is concluded that in elderly individuals apophyseal joint load-bearing above a threshold of 50% is associated with severe degenerative changes in cartilage and bone, and that markers of DJD observed palaeopathologically may be used as predictors of such loadingin life.     

Inhibition of substance P activity prevents stress-induced bladder damage

Substance P is a neuropeptide involved in inflammation, immune regulation and stress response. Stress may induce bladder damage by stimulating inflammatory response such as mast cell activation. We here examined the role substance P during stress-induced mast cell degranulation and urothelial injury in rat bladder. Adult Sprague-Dawley rats (200-270 g) were either exposed to cold-immobilization stress or substance P (SP) intracerebroventricularly. Different doses of substance P receptor (NK1R) antagonist CP 99994 were administered peripherally or centrally before the stress exposure. From each group, samples of the bladder were examined with light and electron microscope. Stress- and SP-injected centrally, increased the number of both granulated and degranulated mast cells. Ultrastructurally, urothelial degeneration with vacuolization in the cytoplasm and dilated intercellular spaces were seen. Both central and peripheral injection of CP 99994 prevented stress-induced urothelial degeneration as well as stress-induced mast cell degranulation. In conclusion, centrally and peripherally released substance P is involved in stress-induced bladder damage. Inhibition of NK1R prevents stress-induced pathological changes of urinary bladder and NK1R antagonist can be considered for the treatment of inflammatory bladder diseases.     

Pathways of load-induced cartilage damage causing cartilage degeneration in the knee after meniscectomy

Results of both clinical and animal studies show that meniscectomy often leads to osteoarthritic degenerative changes in articular cartilage. It is generally assumed that this process of cartilage degeneration is due to changes in mechanical loading after meniscectomy. It is, however, not known why and where this cartilage degeneration starts. Load induced cartilage damage is characterized as either type (1)--damage without disruption of the underlying bone or calcified cartilage layer--or type (2), subchondral fracture with or without damage to the overlying cartilage. We asked the question whether cartilage degeneration after meniscectomy is likely to be initiated by type (1) and/or type (2) cartilage damage. To investigate that we applied an axisymmetric biphasic finite element analysis model of the knee joint. In this model the articular cartilage layers of the tibial and the femoral condyles, the meniscus and the bone underlying the articular cartilage of the tibia plateau were included. The model was validated with data from clinical studies, in which the effects of meniscectomy on contact areas and pressures were measured. It was found that both the maximal values and the distributions of the shear stress in the articular cartilage changed after meniscectomy, and that these changes could lead to both type (1) and type (2) cartilage damage. Hence it likely that the cartilage degeneration seen after meniscectomy is initiated by both type (1) and type (2) cartilage damage.     

The structure of the human symphysis pubis with special consideration of parturition and its sequelae

Review of the structure of the symphysis pubis, based on my extensive study of the pelvic joints ('31) shows changes from age, function, pregnancy hormones and stress of parturition. Primary physiologic shearing clefts and secondary traumatic clefts in cartilage are more frequent in females. Inter-digitations in the young osteocartilaginous border secure the vulnerable growth cartilage against increasing shearing forces. The retropubic eminence, ligamentous or cartilaginous, forms earlier in females, later, due to bony lipping in males, secondary to extrusion of disc cartilage. Ovarian and placental hormones in pregnancy cause remodeling and resorption of the posterior margin of the pubic facette and adjacent cortex, making a (variably) deep bony groove for greatly hypertrophied transverse ligaments. Delivery of a mature infant produces traumatic changes leading to extrusion of torn fibrocartilage in any direction, progressively loosening the symphysis, producing cartilage nodules, cysts and reactive bone formation. Older age degenerative arthritis is more frequent in parous females.     

Changes in the cerebellum of the rat after actinomycin during the postnatal period]

A single dose of actinomycin was applied to young Wistar albino rats in the critical phase of their cerebellar development. The morphological alterations of the cerebellar cortex were studied by means of light and electron microscopy on several postnatal days. The cell types of the cerebellar cortex reacted in different ways toward the noxious substance according to their stage of development. The acute alterations consisted of an edematous reaction of the neuronal and glial perikarya (light degeneration) and a shrinkage of the neurons (dark degeneration). A massive intercellular edema and a rarefaction of glia cells as well as the Purkinje cell fibres proved to be the long-term damage. This pattern of the alteration was discussed regarding the chemodifferentiation of the cells of the cerebellar cortex, the onset of cerebellar function on day 14, and the establishment of a neuroglial functional unit.     

The elastic cartilage in the normal rat epiglottis

Summary Chondrocytes of the rat epiglottis contain large amounts of glycogen and lipids, which often make the cells resemble fat cells. The content of lipids is interpreted as being related to the function of the cells. The membranes of some of the large vacuoles are stained with ruthenium red. The cells give rise to long cytoplasmic processes. As in hyaline cartilage the intercellular substance consists of a fine network containing proteoglycan granules together with thicker cross striated fibers. Furthermore elastic fibers are found, consisting of amorphous and microfibrillar parts. In the matrix, both lysosome-like granules and more or less empty vesicles are observed. Accumulations of a finely particulate electron dense material and of a translucent amorphous material containing membrane bound granules are found in some lacunae situated in the outer part of the cartilage. These accumulations are possibly related to the development of collagenous and elastic fibers.     

Post-traumatic osteoarthritis: the role of accelerated chondrocyte senescence

Joint injuries frequently lead to progressive joint degeneration that causes the clinical syndrome of post-traumatic osteoarthritis. The pathogenesis of osteoarthritis remains poorly understood, but patient age is a significant risk factor for progressive joint degeneration. We have found that articular cartilage chondrocytes show strong evidence of senescence with increasing age, including synthesis of smaller more irregular aggrecans; increased expression of lysosomal beta-galactosidase and telomere erosion; and decreased proteoglycan synthesis, response to the anabolic cytokine IGF-I, proliferative capacity, and mitochondrial function. These observations help explain the strong association between age and joint degeneration, but they do not explain how joint injury increases the risk of joint degeneration in younger individuals. We hypothesized that excessive loading of articular surfaces due to acute joint trauma or post-traumatic joint instability, incongruity or mal-alignment increases release of reactive oxygen species, and that the increased oxidative stress on chondrocytes accelerates chondrocyte senescence thereby decreasing the ability of the cells to maintain or restore the tissue. To test this hypothesis, we exposed human articular cartilage chondrocytes from young adults to mechanical and oxidative stress. We found that shear stress applied to cartilage explants in a triaxial pressure vessel increased release of reactive oxygen species and oxidative stress induced chondrocyte senescence (as measured by expression of lysosomal beta-galactosidase, nuclear and mitochondrial DNA damage and decreased mitochondrial function). These observations support the hypothesis that joint injury accelerates chondrocyte senescence and that this acceleration plays a role in the joint degeneration responsible for post-traumatic osteoarthritis.     

Age-related osteo-arthrotic degeneration of the temporomandibular joint in the mouse

The light-microscopic and ultrastructural characteristics of the temporomandibular joints (TMJs) of female STR/IN mice, aged from 3 to 12 months, were studied. Every TMJ of an adult mouse starts to degenerate in early adulthood and subsequently suffers from osteo-arthrosis. Ageing of the TMJ is characterized by thinning out of its cartilaginous components. The chondrocytes are no longer distributed regularly in the ground substance but form clusters. Cracks and fissures invade the condylar cartilage and lead to the formation of cartilage islands, which finally become loose as free bodies in the lower joint chamber and joint capsule. The lower joint chamber diminishes, but no ankylosis is observed. Ultrastructurally, the number of vesicles around the degenerated chondrocytes increases. Aged chondrocytes contain more lysosomes. The condylar surface becomes irregular and reveals microscars. Its surface is covered by an electron-dense fine granular material, considered to be built up by proteoglycans. Compared to the male ICR mouse, the osteo-arthrotic destruction of the cartilage, the subchondral sclerosis and the deformation of the underlying bone exhibit only minor states in the female STR/IN mouse. Concerning the aetiology and pathogenesis, the very early degeneration of the mostly unloaded TMJ seems to be based on a genetically altered composition of the articular cartilage, possibly due to failing articular chondrocyte responses to stimuli connected with degeneration and repair.     

Polarized Light Technic A Comparison with the Marchi Method

The authors compare polarized light technic for the study of degeneration of myelinated nerves with the Marchi method. While polarized light shows much the same thing, it has the advantages of being much more rapid, more sensitive, and constant. It does not depend on fixation and staining but on the chemical structure of the myelin substance. These changes in structure begin before the third hour after cutting the nerve of a rat. No further technic is involved beside the making of frozen sections. Photographs are presented to illustrate the method.     

Electron microscopy of human articular cartilage]

Scanning and transmission microscopy of the articular cartilage was performed in femoral condyles of persons at the age of 30-50 years. It was demonstrated that hyaline cartilage is covered with a protective fibrillar layer consisting of tightly pressed collagenous fibrillae with an underlying layer of fibroblastic cells. In the intracellular substance of the hyaline cartilage fibrillar structures form a complex reticular web with vertical arrangement of the main collagenous fasiculi. In the superficial layer of the hyaline cartilage the collagenous fibrillae and their fasciculi form arcade-like structures. Lacunar chondrocytes have a rough villose surface, cellular secrete is discharged as round granules through cytoplasmic membrane. Ultrastructural changes in chondrocytes are observed simultaneously with their degenerative-dystrophic changes.     

Articular-cartilage proteoglycans in aging and osteoarthritis.

The composition of macroscopically normal hip articular cartilage obtained from dogs of various ages was studied. Pieces of cartilage with signs of degeneration were studied separately. In normal aging, the extraction yield of proteoglycans decreased; the keratan sulphate content of extracted proteoglycans increased and the chondroitin sulphate content decreased. The extracted proteoglycans were smaller in the older cartilage, mainly owing to a decrease in the chondroitin sulphate-rich region of the proteoglycan monomers. The hyaluronic acid-binding region and the keratan sulphaterich region were increased and the molar concentration of proteoglycan probably increase with increasing age. The degenerated cartilage had higher water content and the proteoglycans, as well as other tissue components, gave higher yields. The proteoglycan monomers from the degenerated cartilage were smaller than those from normal cartilage of the same age, and hence had a smaller chondroitin sulphate-rich region and some of the molecules also appeared to lack the hyaluronic acid-binding region. Increased proteolytic activity may be involved in the process of cartilage degeneration.     

Osteoarthrosis in guinea pigs: histopathologic and scanning electron microscopic features

Spontaneous cartilage degeneration of the femorotibial joint of male Hartley guinea pigs, 61 to 365 days old, was studied by light microscopy (LM) and scanning electron microscopy (SEM) to determine the incidence, age at onset, and to characterize the early changes. Knee joints of 61 day old animals were histologically and ultrastructurally normal. Focal minimal degeneration characterized by cell and proteoglycan loss with surface fibrillation was first observed by LM on the medial tibial plateau (MTP) in two of five 89 day old animals. Mild lesions characterized by focal surface disruption, primarily in the area of medial tibial plateau not covered by the meniscus, were observed in three of five 89 day old animals by SEM. Light microscopic alterations in knee joints of 4, 5, and 6 month old animals consisted of varying degrees of focal chondrocyte death, decreased toluidine blue matrix staining, and surface fibrillation. Small chondrocytic clones were first observed in medial tibial cartilage of 6 month old animals with moderate focal degeneration. Ultrastructurally, 4, 5, and 6 month old animals generally had moderate to severe fibrillation involving primarily the area of the medial tibial plateau not covered by the meniscus. Tibial osteophyte formation, mild synovial hyperplasia, medial femoral and meniscal cartilage degeneration, were first seen by LM in 9 month old animals. Lesions in 1 year old animals were similar, but more severe and included subchondral sclerosis of medial tibial and femoral bone. Bilateral fibrillation of greater than 50% of the medial tibial articular surface was observed in all 1 year old animals by SEM.(ABSTRACT TRUNCATED AT 250 WORDS)     

Permeability and shear modulus of articular cartilage in growing mice

Articular cartilage maturation is the postnatal development process that adapts joint surfaces to their site-specific biomechanical demands. Understanding the changes in mechanical tissues properties during growth is a critical step in advancing strategies for orthopedics and for cell- and biomaterial- based therapies dedicated to cartilage repair. We hypothesize that at the microscale, the articular cartilage tissue properties of the mouse (i.e., shear modulus and permeability) change with the growth and are dependent on location within the joint. We tested cartilage on the medial femoral condyle and lateral femoral condyle of seven C57Bl6 mice at different ages (2, 3, 5, 7, 9, 12, and 17 weeks old) using a micro-indentation test. Results indicated that permeability decreased with age from 2 to 17 weeks. Shear modulus reached a peak at the end of the growth (9 weeks). Within an age group, shear modulus was higher in the MFC than in the LFC, but permeability did not change. We have developed a method that can measure natural alterations in cartilage material properties in a murine joint, which will be useful in identifying changes in cartilage mechanics with degeneration, pathology, or treatment.     

Changes in the metabolism of chondrocytes after chronic intake of phenol and lead

White rats and guinea pigs were given phenol (0.2 and 10 mg/kg) or lead acetate (10 mg/kg of the body mass) for 3-6 months. Intensity of biosynthesis was estimated by glycosaminoglycane cells and by collagene (by means of 35S and 3H-glycine inclusion), distribution of glycoproteids, glycogene and alcaline phosphomonoesterase. The intensity of glycosaminoglycanes biosynthesis decrease in chondrocytes, as does glycogene content and alcaline phosphomonoesterase activity in the zones of the cartilage mineralization. In the intercellular cartilage substance, sertain deviations in quantity and in artio of different types of macromolecules appear, that results in decreasing rates of the cartilage substitution and of the osseous trabecules growth and in development of osteoporosis.     

Deletion of Dual Specificity Phosphatase 1 Does Not Predispose Mice to Increased Spontaneous Osteoarthritis

Background

Osteoarthritis (OA) is a degenerative joint disease with poorly understood etiology and pathobiology. Mitogen activated protein kinases (MAPKs) including ERK and p38 play important roles in the mediation of downstream pathways involved in cartilage degenerative processes. Dual specificity phosphatase 1 (DUSP1) dephosphorylates the threonine/serine and tyrosine sites on ERK and p38, causing deactivation of downstream signalling. In this study we examined the role of DUSP1 in spontaneous OA development at 21 months of age using a genetically modified mouse model deficient in Dusp1 (DUSP1 knockout mouse).

Results

Utilizing histochemical stains of paraffin embedded knee joint sections in DUSP1 knockout and wild type female and male mice, we showed similar structural progression of cartilage degeneration associated with OA at 21 months of age. A semi-quantitative cartilage degeneration scoring system also demonstrated similar scores in the various aspects of the knee joint articular cartilage in DUSP1 knockout and control mice. Examination of overall articular cartilage thickness in the knee joint demonstrated similar results between DUSP1 knockout and wild type mice. Immunostaining for cartilage neoepitopes DIPEN, TEGE and C1,2C was similar in the cartilage lesion sites and chondrocyte pericellular matrix of both experimental groups. Likewise, immunostaining for phosphoERK and MMP13 showed similar intensity and localization between groups. SOX9 immunostaining demonstrated a decreased number of positive cells in DUSP1 knockout mice, with correspondingly decreased staining intensity. Analysis of animal walking patterns (gait) did not show a discernable difference between groups.

Conclusion

Loss of DUSP1 does not cause changes in cartilage degeneration and gait in a mouse model of spontaneous OA at 21 months of age. Altered staining was observed in SOX9 immunostaining which may prove promising for future studies examining the role of DUSPs in cartilage and OA, as well as models of post-traumatic OA.     

circRNA_0058097 promotes tension-induced degeneration of endplate chondrocytes by regulating HDAC4 expression through sponge adsorption of miR-365a-5p

Excessive mechanical tension can lead to the degeneration of endplate chondrocytes. The presence of tension-sensitive circRNA_0058097 molecules has been detected in human endplate chondrocytes, where it was found to be a potential competing endogenous RNA. Indeed, inhibiting the expression of circRNA_0058097 effectively enhanced the stress resistance of endplate chondrocytes, suggesting that it may be an important trigger point for the degeneration of endplate cartilage. Through a series of experiments, we reveal that circRNA_0058097 can upregulate the expression of downstream target gene histone deacetylase 4 by sponge adsorption of miR-365a-5p, which promoted morphological changes of endplate chondrocytes, and increased extracellular matrix degradation and degeneration of endplate cartilage. Therefore, circRNA_0058097 may provide a new way to prevent and treat endplate cartilage degeneration.     

The structure of the arteries at the base of the brain in young and adult dwarf goats. 2. Age-associated changes

Age-associated changes in cerebral arteries of 6 years old pygmy goats were investigated quantitative-histologically. No atherosclerotic alterations could be observed. But age-related thickenings of the subendothelial lamina till to 7 microns were present. Beside a significant increases of the intima, also an increase of the media as also of some lumina could be seen. In relation to the increase of the arterial lumen, the increase of the media was more rapid. Apparently more intercellular substance is formed by the smooth muscle cell during age. These studies confirm only weak intimal thickenings of the cerebral arteries during ageing. They do not effect the blood supply of the brain.     

Human articular cartilage in relation to age, A morphometric study.

The cell density of the weight-bearing area of normal femoral head cartilage was investigated in 65 cases of both sexes ranging from 6 to 90 years of age. In the maturing cartilage (until about the third decade), the cell density decreases, while in aging cartilage (30-90 years) it remains constant. Our results are in agreement with the main trend of earlier and similar investigations. The reason for contradictory reports is suggested to be due to differences in the selection of criteria for defining 'normal' cartilage. This problem is particularly acute with advancing age, where a great part of the available material shows degenerative changes.