Search PubMed⌕ Search

Biomedical subjects

I Kiviranta

Publications and source records attributed to I Kiviranta.

At least 73 records · Page 4Linked to original sources
PubMed1988

A semiquantitative method of recording experimental tooth erosion and estimating occlusal wear in the rat.

As the erosive agent, a sport-drink mixture with pH 3.2 was given to Osborne-Mendel rats for 6 weeks. Lingual surfaces of the right first mandibular molar crowns were chosen for the recording. With the aid of a drawing tube mounted on a stereomicroscope, enlarged drawings of the surfaces were made encircling the intact and eroded areas. A computer-coupled analyser was used to measure the areas of the total surface, intact surface, eroded enamel and exposed dentine in square millimetres. The data was evaluated statistically and used to calculate erosion changes and to estimate occlusal wear.

Animals↗
PubMed1988

Running exercise as a modulatory of proteoglycan matrix in the articular cartilage of young rabbits.

Proteoglycans (PGs) and collagen were quantified in the knee articular cartilages of femoral and tibial medial condyles following 1-8 weeks of moderate running exercise of 4- to 6-month-old rabbits. The total content of PGs extractable with 4 mol/l guanidium chloride was elevated in the weight-bearing cartilage of the tibial medial condyle, while their concentration, expressed as uronic acid per wet weight, and collagen remained unchanged. The content of glucosamine (GlcN) and its ratio to galactosamine (GalN) was elevated in femoral cartilage PGs purified by centrifugation in dissociative CsCl gradients, indicating an increase in keratan sulfate. After 8 weeks of running, the chondroitin sulfate chains of PGs from tibial medial condyle contained less unsulfated disaccharide units. The content of chondroitin sulfate was elevated in the nonextractable residue of the tibial medial condyle as indicated by uronic acid and GaN assays. The content of nonextractable GlcN was increased even more, both in tibial medial and femoral cartilages. Moderate running thus increased (1) keratan sulfate-rich PGs, (2) the degree of sulfation of the chondroitin sulfate chains, and (3) nonextractable PGs; these modulatory alterations probably enhance the stability and elastic stiffness of the PG matrix.

Animals↗
PubMed1988

Erosive effect of a sport drink mixture with and without addition of fluoride and magnesium on the molar teeth of rats.

A sport drink mixture (pH 3.2), either as such or supplemented with 15 ppm F or 38.5 ppm Mg or both, was given to Osborne-Mendel rats as the only liquid for 42 days. The erosion was scored on the lingual surfaces of the first mandibular molar teeth. Sport drink caused marked erosion, but in the groups where fluoride, alone or with magnesium, was added to the drink, the erosion damages were less severe. Magnesium alone had no clear effect on erosion. Dental plaque, induced by a powdered diet containing 15% sucrose, seemed to modify the erosion process by covering a part of the enamel and thus protecting these areas from the direct effect of acidic drink.

Animals↗
PubMed1988

Blood flow, histomorphology and elemental composition of the canine femur after physical training or immobilization.

Effects of long-term physical training (treadmill running 4 km/day for 15 weeks) and immobilization (casting of the limb for 11 weeks) on the blood flow, bone marrow uptake of radio-colloid, histomorphology as well as elemental composition of the proximal canine femur were investigated. In the runners both bone marrow and mean bone perfusions measured with a 133Xe washout method were increased by 53.5% (P less than 0.05) and 54.1% (P less than 0.05), respectively, as compared with the age-matched controls. Bone marrow uptake of [99mTc]tincolloid and volumetric fractions of trabecular bone and bone marrow were not significantly altered after training or immobilization. The amount of zinc measured by atomic absorption spectrophotometry was, however, significantly higher (P less than 0.01) after immobilization as compared with the controls. Consequently, long-term physical training is suggested to stimulate bone metabolism by enhancing its blood perfusion even in the resting state, whereas the increase of zinc content was considered to be linked to the obvious bone resorption caused by immobilization.

Animals↗
PubMed1988

Effects of joint loading on articular cartilage collagen metabolism: assay of procollagen prolyl 4-hydroxylase and galactosylhydroxylysyl glucosyltransferase.

The degree of joint loading on the femoral head cartilage was experimentally altered in dogs by splinting of the knee joint for 11 weeks (n = 9), and making another group (n = 6) to run on a treadmill with 15 degrees uphill inclination during a period of 15 weeks (4 km/day, 5 days a week). A third group (n = 9) served as controls. The influence of these altered loading conditions on articular cartilage collagen synthesis was measured by assaying the activity of procollagen prolyl 4-hydroxylase (PPH) and galactosylhydroxylysyl glucosyltransferase (GGT) in chondrocytes. The average activity of PPH was 11-13% elevated in the runner and contralateral (more loaded) cartilages, while the splinted (unloaded) cartilages showed a significant (53%) increase of PPH. In some samples of the runner, splinted and contralateral cartilages the activity of GGT was also high, but the differences did not reach statistical significance. The increase of the activity of PPH, combined with unaltered total content of collagen, indicates that the synthesis of collagen and probably also its turnover, are enhanced in the cartilage atrophied due to reduced weight-bearing, but only slightly, if at all in the cartilages subjected to moderately elevated loading.

Animals↗
PubMed1987

Weight bearing controls glycosaminoglycan concentration and articular cartilage thickness in the knee joints of young beagle dogs.

Casting of the right knee (stifle) joints of young beagle dogs for 11 weeks caused up to 48% reduction in the glycosaminoglycan (GAG) concentration of the uncalcified articular cartilage, as assessed by a new microspectrophotometric method. The GAGs were depleted mainly in the superficial zone of the cartilage. Although the thickness of the uncalcified cartilage was not decreased, the calcified cartilage under the tidemark was thinned by 6-25% at the femoral condyles. The increased weight-bearing in the limb opposite the one in the splint caused uncalcified cartilage thickness to be augmented by 19% and GAG concentration by 25-35% in the intermediate, deep, and calcified zones of the summits of the femoral condyles; the changes were smaller in other, less loaded parts of the joint. It is concluded that in young dogs, increased weight-bearing augments local proteoglycan content of the articular cartilage matrix, while unloading reduces it.

Animals↗
PubMed1987

Maturation of proteoglycan matrix in articular cartilage under increased and decreased joint loading. A study in young rabbits.

The right knees of 4-month-old NZW rabbits were splinted in extension for 1 to 8 weeks. Biochemical changes of the knee articular cartilage were noted after decreased (splinted leg) and increased loading (created by the shift of body weight onto the left, contralateral limb). Increased loading accelerated changes associated with maturation of articular cartilage, which include accumulation of hyaluronic acid (HA) and keratan sulfate-rich proteoglycans (KS, PG) that are tightly bound to the tissue. After 8-weeks of splinting the content of extractable PGs in the tibial medial condyle decreased. The lost material was apparently replaced by PGs with a higher degree of sulfation of the chondroitin sulfate (Ch-S) chains. Reduced loading disturbed normal maturation as evidenced by inhibition of the accumulation of KS-rich, non-extractable PGs. Collagen content increased in all samples of different joint sites and groups during the 8-week experiment. The content of extractable PGs decreased slightly, while the content of non-extractable, especially KS-rich PGs increased. The greatest changes occurred in the tibial medial condyle, where the KS content was highest.

Age Factors↗
PubMed1987

Topographical variation of glycosaminoglycan content and cartilage thickness in canine knee (stifle) joint cartilage. Application of the microspectrophotometric method.

A recently developed microspectrophotometric method was used to measure local changes of thickness and glycosaminoglycan (GAG) content in articular cartilage. The intensity of the GAG stain was recorded from the superficial, intermediate, deep and calcified zones of articular cartilage. At each site of analysis, both the average stain concentration and the total stain content were determined. Of the 10 predefined locations of the Beagle knee (stifle) joint, the thickest cartilage was observed in the medial condyle of the tibia, which also possessed the highest GAG concentration. In the femur, the summits of the condyles had 33% thicker cartilage than the peripheral parts, while the GAG concentration was about equal in both of these regions. The thinnest cartilage and smallest GAG concentration was at the posterior end of the lateral condyle of the femur. The GAG content in the medial condyle and in the patellar surface of the femur was slightly greater than that in its lateral condyle.

Animals↗
PubMed1986

Effect of physical exercise on indentation stiffness of articular cartilage in the canine knee.

Using the indentation method, we investigated the effects of physical exercise (treadmill running 4 km/day for 15 weeks) on stiffness of the articular cartilage in the canine knee. Considering cartilage to be an elastic material with homogeneity and isotropy, we calculated elastic moduli for femoral, tibial, and patellar cartilages using instant and 15-s deformations after load application. Although the elastic moduli do not represent, because of the non-equilibrium condition, true elastic properties of articular cartilage, they characterize, together with the retardation time spectrum, the integrated response of articular cartilage during the first 15 s after load application. The moderate loading used in our training program caused no macroscopic changes on the articular surface. In running dogs, the mean stiffness of articular cartilage increased by 6% as compared with the controls. Stiffening, which was attributed to the decreased fluid flow in the cartilage, was significant (P less than 0.05) on the patellar surface of the femur and on the tibial condyles. In general, stiffness increased more (approximately 10%) in the cartilage areas, which were repeatedly heavily loaded during running exercise. This alteration in the biomechanical property as well as an increase (approximately 11%) in thickness were considered to be typical responses of articular cartilage to an increased, but physiologic loading pattern.

Animals↗
PubMed1986

Softening of canine articular cartilage after immobilization of the knee joint.

Using the indentation method, effects of immobilization with a splint for 11 weeks on the stiffness of the articular cartilage in the canine knee were investigated. Stiffness was determined for femoral, tibial, and patellar articular cartilages with nine, eight, and three test points, respectively, in the form of elastic moduli. Immobilization, without causing any macroscopic changes on cartilage surface, influenced the quality and quantity of articular cartilage. Immobilization caused significant softening of the femoral and tibial cartilages. The rate of deformation under the test load increased (42%) and the average thickness of the cartilage decreased (9%) as compared with the controls. Normal cartilage stiffness remained in the contact area between the patella and patellar surface of the femur, probably as a consequence of the sustained, but not forceful, loading between the femur and the patella produced by the flexion of the knee joint.

Animals↗
PubMed1985

Microspectrophotometric quantitation of glycosaminoglycans in articular cartilage sections stained with Safranin O.

A new microspectrophotometric method was developed for quantitation of glycosaminoglycans with Safranin O dye in articular cartilage matrix. From histological sections molar extinction coefficient of Safranin O was determined and used to measure the dye content of the sections. The amount of glycosaminoglycans was determined with depth of bovine articular cartilage by both gas chromatography and thin layer chromatography to calculate the fixed negative charge content. Comparison between the results revealed that binding of Safranin O to glycosaminoglycan polyanions was stoichiometric and showed minimal nonspecific staining. The method provides an accurate technique for quantitation and localization of fixed negative charge content of glycosaminoglycans in the articular cartilage matrix. Specific enzyme digestions enable detection of separate glycosaminoglycans.

Animals↗
PubMed1985

Demonstration of chondroitin sulphate and glycoproteins in articular cartilage matrix using periodic acid-Schiff (PAS) method.

Staining of articular cartilage by the periodic acid-Schiff (PAS) method was measured using microspectrophotometry. Standard PAS technique with 2 h oxidation produced a distinct Schiff reaction in the cartilage sections. The staining increased with depth of the articular cartilage demonstrating distribution of the glycoproteins. The modified PAS method included a second, longer periodic acid treatment, which made the uronic acid of glycosaminoglycans PAS-positive. The modified PAS method proved to be highly specific for chondroitin sulphate, which was determined from the samples with gas chromatography. A statistically significant correlation between the Schiff reactivity and galactosamine content of the sections was observed. It is concluded that for articular cartilage standard and modified PAS methods are useful procedures for demonstrating local changes of glycoproteins and chondroitin sulphate, respectively.

Animals↗
PubMed1985

Prolonged ethanol replacement by CO2 increases splits on articular cartilage surface after critical point drying.

Ethanol replacement by CO2 of glutaraldehyde-fixed and ethanol-dehydrated rabbit articular cartilage specimens was monitored with both gas chromatograph and alcometer prior to critical point drying (CPD). The surface structure of the patellar specimens was also systematically registered with a semiquantitative scanning electron microscopic method. After a 2 h interval, when about 28 microliters of ethanol/15 min CO2 extract was removed, the articular surface was smooth, although small areas of striated surface and superficial splits were present. A long-term CO2 treatment (16 h) removed ethanol completely, but increased superficial splitting of the articular surface after CPD. Air-drying of the specimens gave rise to inferior preservation of the cartilage: large areas with pitted and leafy surface qualities, but no superficial splits, were present on the surface. It was evident that prolonged ethanol replacement by CO2, prior to CPD, degraded surface structure of the articular cartilage which should be taken into consideration in the planning and design of experiments. Ethanol removal by CO2 could conveniently be monitored by an alcometer.

Animals↗
PubMed1985

Influences of joint immobilization and running exercise on articular cartilage surfaces of young rabbits. A semiquantitative stereomicroscopic and scanning electron microscopic study.

The influences of joint immobilization and running exercise on the articular cartilage surfaces of the patella and lateral tibial condyle of young rabbits were investigated by the semiquantitative stereomicroscopic and scanning electron microscopic methods during a period of 8 weeks. The smoothness of the articular surfaces was disturbed already 1 week after the onset of immobilization. Leafy, slightly rough and rough surface qualities associated with superficial splits were observed. The changes were of the same nature after a longer period of immobilization. Running exercise on the treadmill (150-300 m twice a day, 12-24 min per turn, 5 times a week) led to an increase of the striated surface quality at 1 to-2-week intervals as compared with the controls. It was apparent that during immobilization remarkable changes of the articular cartilage took place within the first week, while running exercise up to 8 weeks elicited only transient or minor alterations of the articular surface.

Animals↗
PubMed1984

Quantitative morphological and biochemical investigations on the effects of physical exercise and immobilization on the articular cartilage of young rabbits.

The effects of physical exercise and immobilization on the knee joint articular cartilage of young rabbits (2.5 to 5 months of age) were investigated by quantitative histology, semiquantitative stereomicroscopy and scanning electron microscopy as well as biochemical methods, during a period of 8 weeks. Physical exercise increased the cell size in all zones of the uncalcified cartilage without notable concomitant change in the cell density. It also increased the volume density of the cells in the intermediate and deep zones. Increased striation of the cartilage surface was observed after 1 week's running period, suggesting superficial appearance of collagenous fibres and depletion of the proteoglycans on account of the exercise. However, after 4 to 8 weeks of running the increase of the striated surface was no longer significant. At the same time the proteoglycan content increased with preponderance of keratan sulfate-rich proteoglycans. Immobilization of the knee joint decreased slightly the cell size but increased the cell density in the superficial zone. Immobilization caused derangement of the smoothness of the articular surface already at the end of the 1st week with superficial splitting of the surface. Reduction of the cartilage matrix proteoglycans and collagen was observed after 1 week's immobilization. In the whole femoral surface, but not in the weight-bearing area of tibial lateral condyle, the proteoglycan content was replenished with chondroitin sulfate-rich molecules by the end of the 8th week after immobilization. Both physical exercise and immobilization caused significant intracondylar remodelling of the articular cartilage.

Animals↗