Wendelin J. Paule

AGE CHANGES TO THE ANULUS FIBROSUS IN HUMAN INTERVERTEBRAL DISCS

This study deals with age changes in the anulus fibrosus of the lumbar intervertebral discs of human individuals 21-83 years of age. The anular laminas from individuals less than 40 years of age consisted of obliquely orientated collagen fibers exhibiting a pennate arrangement. These fibers were intensely argyrophilic after silver nitrate impregnation. The fibers and surrounding substance appeared light pink after exposure to the periodicacid- Schiff (PAS) reaction and blue with alcian blue complex. Beginning during middle age and continuing into the eighth decade, there was a progressive degeneration of the laminas. The breakdown of the intact laminas was characterized by the fraying, splitting, and loss of collagen fibers. The newly formed spaces became filled with intense PAS-positive material. In addition, there was a continual deposition of chondroid substance in the anuluses of the aging discs. This phenomenon was not seen in the young disc. These age related changes lead to a loss of integrity to the disc, which may be a factor in disc pathology.

Biochemical differences between dystrophic calcification of cross-linked collagen implants and mineralization during bone induction

SummaryEctopic calcification of diseased tissues or around prosthetic implants can lead to serious disability. Therefore, calcification of implants of glutaraldehyde-cross-linked collagenous tissues and reconstituted collagen was compared with mineralization induced by demineralized bone matrix (DBM). Whereas implants of DBM accumulated large amounts of calcium and a bone-specific γ-carboxyglutamic acid protein (BGP or osteocalcin) following implantation in both young and older rats, implants of cross-linked pericardium calcified with only traces of BGP. Glutaraldehyde-cross-linked DBM failed to calcify after implantation in 8-month-old rats for 2–16 weeks. Implants of cross-linked type I collagen exhibited small calcific deposits 2 weeks postimplantation but calcium content eventually dropped to levels equal to those of soft tissues as the implants were resorbed. The calcium content of DBM implanted in 1- and 8-month-old rats reached comparable levels after 4 weeks, but the BGP content was approximately twice as high in the younger animals than in the older ones. Glutaraldehyde-cross-linked implants of DBM, tendon, and cartilage calcified significantly in young but not in old animals. This form of dystrophic calcification was associated with only trace amounts of BGP. Alkaline phosphatase activity was high in implants of DBM and undetectable in implants of cross-linked collagenous tissues. These results show that implants of glutaraldehyde-cross-linked collagenous tissues and reconstituted collagen calcify to different extents depending upon their origin and the age of the host, and that the mechanism of dystrophic calcification differs significantly from the process of mineralization associated with bone induction as reflected by alkaline phosphatase activity and BGP accumulation.

Light- and electron-microscopic characteristics of arterial smooth muscle cell cultures subjected to hypoxia or carbon monoxide

Smooth muscle cells from the tunica media of piglet aortae grown under hypoxic conditions undergo the following changes: First, they become modified by partial loss of myofilaments and proliferation of organelles, which are characteristics of young primitive cells. Second, an increase in number of pinocytotic vesicles at and below the cell surface, indicating increased extracellular uptake of material, can be detected. This is followed by accumulation of Oil Red O positive intracytoplasmic granules and vacuoles as well as the subsequent formation of mount-like protrusions. The latter consist of a core of extracellular material and necrotic debris covered with a cap of viable cells. A third feature of the cells subjected to hypoxia is a conspicuous rise in the number of lysosomes. This is considered to be a manifestation of a defense mechanism of the cells to remove undesirable material from cytoplasm. Cells exposed to an atmosphere rich in carbon monoxide exhibit basically the same alterations as those grown under hypoxic conditions; however, formation of mound-like aggregates is less prominent, while the rise in the number of lysosomes is more evident than in the hypoxic cells. The above alterations are similar to changes observed in smooth muscle cells of rabbit with experimental atherosclerosis. It is suggested that whereever the arterial smooth muscle cell is subjected to adverse conditions basically the same mechanism, consisting of dedifferentiation, increased permeability and lysosomal defense reaction, takes place.

Postmortem degradation of demineralized bone matrix osteoinductive potential. Effect of time and storage temperature.

The osteoinductive growth factors present in demineralized bone are degraded by tissue enzymes. Storage of rat limbs at low temperature (4 degrees C) before harvesting of bones preserves the osteoinductive potential of such factors. Storage at room temperature for more than 24 hours causes the recovered bone matrix to be biologically inactive, presumably as the result of biodegradation.

Changes in the ratio of non-calcified collagen to calcified collagen in human vertebrae with advancing age

Bone loss associated with aging is associated primarily with a decline in bone formation. To try and further understand the nature of this process we have used a biochemical approach which relies on the fact that osteoid is susceptible to enzymatic degradation whereas calcified collagen is protected by the mineral phase against proteolytic digestion. Our findings show a statistically significant inverse relationship between osteoid and age (r = 0.70 female, r = 0.47 male). A closer relationship was observed when age was related to the ratio of osteoid to bone (r = 0.73 female, r = 0.56 male). In both cases, the observed linear decline begins at an early age and becomes marked with advancing age. Histologic observations illustrate these findings showing decreased osteoid and osteoblasts in the older vertebral specimens compared to the younger ones. Even though the mechanism for osteoid calcification seems to remain unimpaired, the decline of a calcifiable matrix in the presence of normal bone turnover could lead to bone loss.

The induction of atherosclerotic plaque-like mounds in cultures of aortic smooth muscle cells

SummarySmooth muscle cells harvested from the tunica media of piglet aortae were maintained in continuous culture for 10 months. When grown in the presence of 95% air and 5% CO2 they maintained a mature morphology as evaluated ultrastructurally. As these populations became confluent, the cells became oriented parallel to each other. When grown in the presence of 4% O2, 91% N2, and 5% CO2, this polarized pattern was disrupted. Focal areas of lipid accumulation were observed, succeeded by mound formation at these sites. The mound stained positive with PAS, aldehyde fuchsin, and oil red O. They were surrounded by 2—4 layers of intact cells. The centers of the mounds were composed of extracellular material and cell debris.

DYSTROPHIC CALCIFICATION AND MINERALIZATION DURING BONE INDUCTION: BIOCHEMICAL DIFFERENCES

The calcification of implants of glutaraldehyde-crosslinked collagenous tissues and collagen was studied in young and old rats and compared to bone induction by non-crosslinked osteogenically active demineralized bone matrix (DBM). Glutaraldehyde-crosslinked implants of DBM, tendon, and cartilage calcified in young but not in old animals and accumulated only trace amounts of BGP (Bone Gla protein, osteocalcin). Alkaline phosphatase activity was high in implants of DBM and undetectable in crosslinked implants. To try and understand why bone formation is so significantly reduced in older Fischer-344 rats, we developed a system which consists of cylinders of DBM sealed at the ends with a Millipore filter. Cells originating from 20-day-old embryo donors were introduced into the chambers prior to subcutaneous implantation. After 4 weeks of implantation in 26-month-old rats, the cylinders containing embryonic calvaria or muscle calls were found to be full of bone and/or cartilage.

Morphological Changes in the Aging Mammalian Pancreas

A comprehensive description of morphological and cytological changes in the aging mammalian pancreas has not been reported. What works have been published consist of light microscopic descriptions of a variety of histopathologic lesions in both the aging exocrine and endocrine pancreas. While this chapter deals specifically with the area of age-related cytomorphologic changes in the mammalian pancreas, emphasis will be placed on a description of the endocrine pancreas. This is not difficult to understand in light of the relationship of the endocrine pancreas to diabetes mellitus, a disease mainly of the aged population.

Leeftijdsgebonden veranderingen in de annulus fibrosus van mensalijke intervertebrale disci

Dit onderzoek richtte zich op de leeftijdsgebonden veranderingen in de annulus fibrosus van de lumbale intervertebrale disci van de mens in de leeftijd tussen 21–83 jaar. De annuluslamellen bij mensen jonger dan veertig jaar, bestonden uit schuingerichte collagene vezels, die in een veervormige rangschikking waren geplaatst. Deze vezels werden intens argyrofiel na impregnering met zilvernitraat. De vezels en omringende materie kleurden lichtroze na blootstelling aan de periodiek-zuur-Schiff (pas)- reactie en blauw bij het alciaan- blauw-complex.