Studies on intervertebral disc protrusion in beagles

The serine proteinase inhibitory proteins of the chondrodystrophoid (beagle) and non-chondrodystrophoid (greyhound) canine intervertebral disc

Trypsin inhibitory proteins of low buoyant density (p < or = 1.35 g/mL) fractions were prepared by CsCl density gradient ultracentrifugation of 4 M guanidinium hydrochloride extracts of lumbar beagle and greyhound annulus fibrosus and nucleus pulposus from animals aged 1 to 6 years. Affinity blotting with biotinylated trypsin was used to identify active trypsin inhibitory protein species; these species were also identified immunologically by Western blotting using antibodies against bovine pancreatic trypsin inhibitor (BPTI), and human inter-alpha-trypsin inhibitor (ITI). None of the trypsin inhibitory species evident in Western blots were reactive with anti-human alpha1-proteinase inhibitor (alpha-1-PI), alpha2-macroglobulin or secretory leucocyte proteinase inhibitor. The greyhound intervertebral disc samples generally had higher levels of active trypsin inhibitor species per unit weight of tissue extracted, and a more extensive range of inhibitor species. Inhibitor species of 30, 32, 34 kDa were identified in both beagle and greyhound intervertebral disc samples; these species were generally most prominent in the annulus fibrosus samples. In contrast, the nucleus pulposus samples contained relatively large trypsin inhibitor species; the anti-BPTI detected an inhibitor species of approximately 85-90 kDa; anti-ITI detected species of 120-250 kDa; biotinylated trypsin detected species of 60-110 kDa. A small molecular mass trypsin inhibitor species of 6 kDa, which was of similar mobility to BPTI, was also detected in annulus fibrosus samples; however, this species did not react with anti-BPTI.

Intervertebral disc reconstitution after chemonucleolysis with chymopapain is dependent on dosage

STUDY DESIGN

The current report describes a study in beagles in which the effects of intradiscal injection of three doses of chymopapain were evaluated with respect to the reduction of disc width and reconstitution of the nucleus pulposus.

OBJECTIVES

To establish an intradiscal dose of chymopapain that would achieve optimal reduction in disc height followed by maximum reconstitution of the nucleus pulposus.

SUMMARY OF BACKGROUND DATA

Earlier reports of the efficacy of high and low doses of chymopapain for chemonucleolysis have provided conflicting data, and a scientific basis for an appropriate dose is lacking.

METHODS

Four mature, female beagles were subjected to chemonucleolysis using three doses of chymopapain as Chymodiactin (31, 63 and 125 picokatals/disc) injected into the L2-L3, L1-L2, and L3-L4 discs. Disc widths were monitored radiographically over 32 weeks. Proteoglycans were radiolabeled by intravenous injection with Na2 35SO4 (1 mCi/kg) 24 hours before sacrifice, and their specific activities (disintegrations per minute/mg proteoglycan), hydrodynamic size, and ability to aggregate determined.

RESULTS

Sixty-three picokatals of Chymodiactin produced optimal disc reconstitution after chemonucleolysis. A reduction in disc height of approximately 35% was evident within 1 month and this slowly returned to approximately 90% of the preinjection value after 32 weeks. The nucleus pulposus contained approximately 75% of the proteoglycan content of control tissues, and most of these formed aggregates with hyaluronan. Disc collagen levels remained relatively unaffected by treatment.

CONCLUSIONS

This study demonstrates that an effective reduction in disc width compatible with later reconstitution of the nucleus pulposus can be achieved experimentally with an appropriate dose of chymopapain. These data clearly indicate that an optimal dose of chymopapain for chemonucleolysis in humans needs to be established.

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.

Running training alters fiber type composition in spinal muscles

The issue of whether exercise can induce changes in muscle fiber types has been long debated. Knowledge about the alterations in spinal muscle fiber types is scarce. In this study, the alterations initiated by long-distance running on spinal muscle fiber type distribution was studied. Ten young dogs were run on a treadmill for 55 weeks, 5 days a week, and ten dogs from the same litters served as controls. The daily running distance was gradually increased to 40 km and maintained at that level for the final 15 weeks. Histological sections were prepared from the cervical, thoracic, and lumbar multifidus muscles and the medial and lateral heads of triceps brachii and analyzed for the fiber type composition and cross-sectional area of fibers. In the lumbar multifidus, the numerical percentage of the muscle fibers with low oxidative capacity (type II) increased significantly in the running group. However, in the thoracic and cervical spine multifidus, the response to running resembled more of the significant shift from type II to type I fibers (with high oxidative capacity), which was also observed in the triceps brachii muscle. In these muscles, the quantitative image analysis of nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR) reaction also demonstrated a shift towards a higher oxidative capacity within the type II fibers. The results show that training can induce changes in fiber type composition not only in limb muscles but also in the stabilizing spinal muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Proteoglycan synthesis in canine intervertebral discs after long-distance running training

The alterations and distribution of proteoglycan (PG) synthesis in the intervertebral discs of young dogs exercised with long-distance running (40 km/day) were studied with a method based on image analysis of tissue sections. Ten dogs were run on a treadmill daily for 55 weeks, and 10 dogs from the same litters served as controls. The daily running distance gradually was increased to 40 km and was maintained at that level for the final 15 weeks. Midsagittal disc segments C7-T1, T8-9, and L1-2 were labeled with 35SO4, and histological sections of the segments were apposed against autoradiographic film to determine the synthesis of PGs. Next, the same sections were stained with safranin O to estimate possible alterations in PG concentration. The radiographs and stained sections were digitized with a flatbed scanner and measured by image analysis. The lumbar discs of runners displayed a significantly lower rate of 35SO4 incorporation, while a tendency toward enhanced incorporation was seen in the cervical and thoracic discs. Safranin O staining showed a pattern just opposite to 35SO4 incorporation: decreased staining in the cervical and thoracic discs and increased staining in the lumbar discs of the runners. The results demonstrate qualitatively different influences of long-term running training on PG metabolism at the cervical, thoracic, and lumbar levels in young dogs.

A longitudinal study of the matrix changes induced in the intervertebral disc by surgical damage to the annulus fibrosus

A 5 x 5-mm anterolateral incision was made in the annulus fibrosus (AF) of lumbar discs of 16 sheep; four animals of similar age not operated on were used as controls. The experimental animals were sacrificed 2, 4, 6, 8, 12, and 18 months postoperatively (PO), and the incised and adjacent lumbar discs were collected. Discs were dissected into four zones: AF (zones 1 and 2) and nucleus pulposus (NP) (zones 3 and 4) corresponding to the half of the AF in which the cut was made and its opposite half, and the complementary halves of the NP. Each zone was analyzed for moisture, proteoglycan (PG), collagen, and noncollagenous protein (NCP) content. The PG extractability, aggregation, and hydrodynamic size were also examined. The NP of injured discs showed a significant loss of PGs and collagen 8 months PO, but NCP levels increased. In the incised discs, PG aggregation initially declined but recovered to within control values 6-8 months PO. The NP of discs adjacent to the incised disc also showed time-dependent changes in matrix components that included loss of collagen and PG; however, the AF matrix remained essentially uneffected. Double immunodiffusion studies indicated that a sizeable proportion of the NCPs present in the injured discs (but not the adjacent lumbar discs) were derived from serum.