Papain-induced changes in intracellular lipid levels in cartilage

Loss of proteoglycans from the cartilage matrix of the ears of young rabbits was induced by intravenous injection of papain so as to permit histochemical observation of lipid levels in chondrocytes during both the depletion process and subsequent proteoglycan synthesis by the chondrocytes. Lipid content was quantified using an image analyser. Between 4 and 24 h after injection, loss of proteoglycans was accompanied by a fall in intracellular fat levels. In the 24- to 120-hour post-injection period, matrix proteoglycan levels and basophilia recovered parallel to the intracellular fat content. The function of intracellular lipids in cartilage is discussed in the light of these results.     

Osmotic loading to determine the intrinsic material properties of guinea pig knee cartilage

Few methods exist to study cartilage mechanics in small animal joints due to the difficulties associated with handling small tissue samples. In this study, we apply an osmotic loading method to quantify the intrinsic material properties of articular cartilage in small animal joints. Cartilage samples were studied from the femoral condyle and tibial plateau of two-month old guinea pigs. Swelling strains were measured using confocal fluorescence scanning microscopy in samples subjected to osmotic loading. A histochemical staining method was developed and calibrated for quantification of negative fixed charge density in guinea pig cartilage. Site-matched swelling strain data and fixed charge density values were then used with a triphasic theoretical model for cartilage swelling to determine the uniaxial modulus of the cartilage solid matrix. Moduli obtained in this study (7.2 MPa femoral condyle; 10.8 MPa, tibial plateau) compare well with previously reported values for the tensile moduli of human and other animal cartilages determined from uniaxial tension experiments. This study provides the first available data for material properties and fixed charge density in cartilage from the guinea pig knee and suggests a promising method for tracking changes in cartilage mechanics in small animal models of degeneration.     

A deep-etching study of the guinea pig tracheal cilium with special reference to the ciliary transitional region

The fine structure of the cilium was examined by freeze-fracture-etch studies. In the interior of the transitional region, three types of plate structures were clearly observed. While the terminal plate contained fine fibrillar linkers suspending the central core plates from its peripheral doublet microtubules, two other types of plates had no suspending linkers. At the upper level of transitional region, one of the central microtubules elongated deeper than the other in the space surrounded by ring structure. Axosome-like structure was not observed in our replicas. Central vesicle of the basal body was also suspended by fine fibrillar linkers from peripheral triplets. Though membrane particles of ciliary necklace were recognized on protoplasmic and external fracture faces, and the external surface, particle arrays were not observed on protoplasmic surface. Instead, Y-shaped, cross bridges, one end of which attached to the doublet microtubules, merged in the circular ridge structure at opposite ends. This circular ridge structure at the necklace region may play a role as an anchoring site of both membrane particles of the necklace and cross bridges from peripheral doublet microtubules.     

Extracellular matrix changes in knee joint cartilage following bone-active drug treatment

Certain drugs or treatments that are known to affect bone quality or integrity might have side effects on the extracellular matrix of articular cartilage. We investigated the effects of vitamin D and calcium deficiency, estrogen deficiency, and hypercortisolism alone or in combination with bisphosphonates or sodium fluoride in an animal model, viz., the Göttingen miniature pig (n=29). The articular cartilage from knee joints was analyzed for its content of glycosaminoglycans (GAGs, as macromolecules responsible for the elasticity of articular cartilage) by a spectrometric method with dimethylene blue chloride. In cryo- or paraffin sections, alkaline phosphatase (AP, as an enzyme indicating mineralization or reorganization of articular cartilage matrix) was localized by enzyme histochemistry, and positive cells were counted, whereas differently sulfated GAGs were stained histochemically. A significant decrease in GAG content was measured in ovariectomized and long-term glucocorticoid-treated animals compared with untreated animals. In the glucocorticoid/sodium fluoride group, GAGs were significantly diminished, and significantly fewer AP-positive chondrocytes were counted compared with the control. GAG content was slightly higher, and significantly more AP-positive chondrocytes were counted in short-term glucocorticoid-treated animals then in the control group. GAGs, as part of proteoglycans, are responsible for the water-storage capacity that gives articular cartilage its unique property of elasticity. Thus, ovariectomy and long-term glucocorticoid therapy, especially when combined with sodium fluoride, have detrimental effects on this tissue.This work was in part supported by Deutsche Forschungsgemeinschaft (DFG) project no. Schr 430/5–1, 5–2 and G 1289/1–1, 1–2     

Subchondral bone and ligament changes precede cartilage degradation in guinea pig osteoarthritis

There is increasing recognition that osteoarthritis (OA) is a complex disease involving the whole synovial joint, rather than the articular cartilage alone, however its aetiology and pathogenesis is not understood. Our initial studies revealed elevated turnover of bone and ligament collagen in human and mouse OA, respectively. To investigate the relative appearance of pathology in cartilage, bone and ligament, we studied the progression of spontaneous OA in the Dunkin-Hartley (DH) guinea pig knee, and compared with age-matched control Bristol Strain 2 (BS2) knees. The classical radiographic OA score of the DH knees compared to BS2 knees was 2-fold higher at 24 weeks of age. The patella perimeter and subchondral bone density was significantly greater in the DHs at 24 and 36 weeks compared to BS2. The femoral intercondylar notch width was found to be significantly lower in the DHs at 24 and 36 weeks, compared to BS2, indicating bone remodelling at the cruciate ligament (CL) insertion site. We found significantly greater laxity of the DH anterior CL at 12, 16 and 20 weeks compared to BS2. This elevated laxity was associated with increased remodelling of the CLs, based on markers of collagen turnover, and occurred prior to bone and cartilage pathology. We propose that the laxity of the CL leads to remodelling of the subchondral bone, and intercondylar notch, due to a change in load through the joint. Remodelling of the CLs and bone occurs prior to and concomitant with histopathological changes in the articular cartilage respectively, demonstrating the fundamental role of the ligament and subchondral bone in the aetiology of knee OA.     

Distribution of NT-IR perikarya in the brain of the guinea pig with special reference to cardiovascular centers in the medulla oblongata

The occurrence and distribution of neurotensin-immunoreactive (NT-IR) perikarya was studied in the central nervous system of the guinea pig using a newly raised antibody (KN 1). Numerous NT-IR perikarya were found in the nuclei amygdaloidei, nuclei septi interventriculare, hypothalamus, nucleus parafascicularis thalami, substantia grisea centralis mesencephali, ventral medulla oblongata, nucleus solitarius and spinal cord. The distribution of NT-IR perikarya was similar to that previously described in the rat and monkey. In the gyrus cinguli, hippocampus and nucleus olfactorius, though, no NT-IR neurons were detected in this investigation. Additional immunoreactive perikarya, however, were observed in areas of the ventral medulla oblongata, namely in the nucleus paragigantocellularis, nucleus retrofacialis and nucleus raphe obscurus. The relevance of the NT-IR perikarya within the ventral medulla oblongata is discussed with respect to other neuropeptides, which are found in this area, and to cardiovascular regulation.     

Distribution of NT-IR perikarya in the brain of the guinea pig with special reference to cardiovascular centers in the medulla oblongata

Summary The occurrence and distribution of neurotensin-immunoreactive (NT-IR) perikarya was studied in the central nervous system of the guinea pig using a newly raised antibody (KN 1). Numerous NT-IR perikarya were found in the nuclei amygdaloidei, nuclei septi interventriculare, hypothalamus, nucleus parafascicularis thalami, substantia grisea centralis mesencephali, ventral medulla oblongata, nucleus solitarius and spinal cord. The distribution of NT-IR perikarya was similar to that previously described in the rat and monkey. In the gyrus cinguli, hippocampus and nucleus olfactorius, though, no NT-IR neurons were detected in this investigation. Additional immunoreactive perikarya, however, were observed in areas of the ventral medulla oblongata, namely in the nucleus paragigantocellularis, nucleus retrofacialis and nucleus raphe obscurus.The relevance of the NT-IR perikarya within the ventral medulla oblongata is discussed with respect to other neuropeptides, which are found in this area, and to cardiovascular regulation.Abbreviations abl nucleus amygdaloideus basalis lateralis - abm nucleus amygdaloideus basalis medialis - acc nucleus amygdaloideus centralis - aco nucleus amygdaloideus corticalis - ahp area posterior hypothalami - ala nucleus amygdaloideus lateralis anterior - alp nucleus amygdaloideus lateralis posterior - ame nucleus amygdaloideus medialis - atv area tegmentalis ventralis - bst nucleus proprius striae terminalis - CA commissura anterior - CC corpus callosum - cgld corpus geniculatum laterale dorsale - cglv corpus geniculatum laterale ventrale - cgm corpus geniculatum mediale - CHO chiasma opticum - CI capsula interna - co nucleus commissuralis - cod nucleus cochlearis dorsalis - cp nucleus caudatus/Putamen - cs colliculus superior - cu nucleus cuneatus - dmh nucleus dorsomedialis hypothalami - DP decussatio pyramidum - em eminentia mediana - ent cortex entorhinalis - epi epiphysis - FLM fasciculus longitudinalis medialis - fm nucleus paraventricularis hypothalami pars filiformis - FX fornix - gd gyrus dentatus - gp globus pallidus - gr nucleus gracilis - hl nucleus habenulae lateralis - hm nucleus habenulae medialis - hpe hippocampus - ift nucleus infratrigeminalis - io oliva inferior - ip nucleus interpeduncularis - LM lemniscus medialis - MT tractus mamillo-thalamicus - na nucleus arcuatus - nls nucleus lateralis septi - nms nucleus medialis septi - npca nucleus proprius commissurae anterioris - ns nucleus solitarius - n III nucleus nervi oculomotorii - nt V nucleus tractus spinalis nervi trigemini - ntm nucleus mesencephalicus nervi trigemini - osc organum subcommissurale - P tractus cortico-spinalis - PC pedunculus cerebri - PCI pedunculus cerebellaris inferior - pir cortex piriformis - pol area praeoptica lateralis - pom area praeoptica medialis - prt area praetectalis - pt nucleus parataenialis - pvh nucleus paraventricularis hypothalami - pvt nucleus paraventricularis thalami - r nucleus ruber - re nucleus reuniens - rgi nucleus reticularis gigantocellularis - rl nucleus reticularis lateralis - rm nucleus raphe magnus - ro nucleus raphe obscurus - rp nucleus raphe pallidus - rpc nucleus reticularis parvocellularis - rpgc nucleus reticularis paragigantocellularis - sch nucleus suprachiasmaticus - SM stria medullaris thalami - snc substantia nigra compacta - snl substantia nigra lateralis - snr substantia nigra reticularis - ST stria terminalis - tad nucleus anterior dorsalis thalami - tam nucleus anterior medialis thalami - tav nucleus anterior ventralis thalami - tbl nucleus tuberolateralis - tc nucleus centralis thalami - tl nucleus lateralis thalami - tmd nucleus medialis dorsalis thalami - TO tractus opticus - TOL tractus olfactorium lateralis - tpo nucleus posterior thalami - tr nucleus reticularis thalami - trs nucleus triangularis septi - TS tractus solitarius - TS V tractus spinalis nervi trigemini - tvl nucleus ventrolateralis thalami - vmh nucleus ventromedialis hypothalami - vh ventral horn, Columna anterior - zi zona incerta Supported by the Deutsche Forschungsgesellschaft (DFG) SFB 90, Carvas     

Turnover of proteoglycans in guinea pig costal cartilage

The turnover in vivo of proteoglycans of guinea pig costal cartilage was investigated using Na₂³⁵SO₄ as precursor. Proteoglycans were extracted with guanidine · HCl, at both low and high ionic strength, and purified and fractionated by ultracentrifugation in CsCl gradients under associative and dissociative conditions. The results suggest that the sulfate is incorporated into macromolecules of at least two major metabolic pools with half-lives of about 3 days and about 60–70 days, respectively. Molecules with a fast turnover were enriched in the low ionic strength extracts and in fractions containing small, nonaggregated proteoglycans. No substantial evidence was found for a precursor-product relationship between different fractions.     

Electron microscopic and enzyme cytochemical studies on the guinea pig metaphysis with special reference to the lysosomal system of different cell types

The effects of chronic administration of dexamethasone (for up to 15 consecutive days) on both the morphology and DNA-synthesis of the mitochondria of the rat adrenal zona fasciculata were investigated by stereologic and autoradiographic techniques. Up to the 3rd day of continuous dexamethasone treatment, the average volume of mitochondria did not change, whereas the number of mitochondria per cell was significantly decreased. From the 3rd to the 15th day of hormonal administration both the volume and number of mitochondria were found to decrease in proportion to the duration of treatment. Autoradiography showed that after the 3rd day of dexamethasone administration there is virtually no incorporation of 3H-thymidine into the mitochondrial compartment. These findings are discussed in the light of evidence indicating that dexamethasone blocks ACTH-release by inhibiting the hypothalamo-hypophyseal axis. The results confirm the view that ACTH controls the maintenance of growth and proliferation of rat adrenocortical mitochondria.     

Innovar-Vet-induced pathologic changes in the guinea pig.

High doses of Innovar-Vet administered im induced pathologic changes in tissues at the site of drug deposition. The onset and extent of the changes were dose related. Distal self-mutilation occurred coincidentally to the peak of pathologic changes in the ischiatic nerve.