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Biomedical subjects

M Tammi

Publications and source records attributed to M Tammi.

At least 109 records · Page 6Linked to original sources
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

Effect of glycosylation on yeast invertase oligomer stability.

Yeast external invertase is a glycoprotein that exists as a dimer that can associate to form tetramers, hexamers, and octamers (Chu, F., Watorek, W., and Maley, F. (1983) Arch. Biochem. Biophys. 223, 543-555; Esmon, P. C., Esmon, B. E., Schauer, I. E., Taylor, A., and Schekman, R. (1987) J. Biol. Chem., 262, 4395-4401), a process that is facilitated by the attached oligosaccharide chains. We have studied this association by high performance liquid chromatography on a gel filtration matrix, by which procedure wild-type bakers' yeast invertase gives two peaks, and invertase from a core mutant (mnn1 mnn9) of Saccharomyces cerevisiae X2180 gives three peaks. Concentration of an invertase solution by freezing drives the dimers into higher aggregates that, at 30 degrees C, re-equilibrate to a mixture of smaller forms, the composition of which depends on pH, concentration, and time. The invertase from a mutant, mnn1 mnn9 dpg1, which underglycosylates its glycoproteins and produces invertase with 4-7 oligosaccharide chains, forms oligomers of much lower stability than the mnn1 mnn9 invertase, which has 8-11 carbohydrate chains. Both of these mutants release external invertase from the periplasm into the medium during growth, but we conclude that defects in the cell wall structure may be more important in this release than an altered tendency of the invertases to aggregate. Investigation of aggregate formation by electron microscopy revealed that all invertases, including the internal nonglycosylated enzyme, form octamers under appropriate conditions.

Chromatography, Gel↗
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

Abnormal dermal proteoglycan in aspartylglycosaminuria: a possible mechanism for ultrastructural changes of collagen fibrils in a glycoprotein storage disorder.

Changes in the structure and organization of collagen fibrils were recently described in the skin of aspartylglycosaminuria patients. The skin of the patients contained a normal amount and distribution of glycosaminoglycans, but the dermatan sulfate of aspartylglycosaminuria skin was more sensitive to chondroitinase AC digestion, resulting in unsaturated 4-sulfated disaccharides which were not detected in controls. Isolated dermatan sulfate chains as well as the chains present in the intact core protein synthesized by skin fibroblasts from an aspartylglycosaminuria patient were also digestible with chondroitinase AC, while those of a control fibroblast culture could be digested with chondroitinase ABC only. This is indirect evidence for abnormal epimerization of dermatan sulfate in the skin of aspartylglycosaminuria patients, which may be associated with the changes in collagen fibril formation.

Acetylglucosamine↗
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

Influence of retinoic acid on the ultrastructure and hyaluronic acid synthesis of adult human epidermis in whole skin organ culture.

Normal human skin was maintained in organ culture under chemically defined conditions. All-trans retinoic acid was added to the culture medium at the final concentration of 5 mumol/l. After 5 days in culture samples were either harvested for electron microscopy or labeled with 3H-glucosamine for 24 h. After labeling, epidermis was separated from dermis and both tissue compartments were analyzed for the content of 3H-labeled glycosaminoglycans (GAGs) using CPC-precipitation and thin layer chromatography after enzymatic degradation into specific disaccharides. Retinoic acid caused a marked change in the epidermal tissue architecture. The epidermal cells were flattened and contained fewer desmosomes and tonofilaments than control explants. Retinoic acid induced accumulation of fine granular material in the intercellular spaces in the upper, and less dense, flocculent material in the lower epidermis. The analysis of 3H-glycosaminoglycans showed that in the epidermis retinoic acid elevated the amount of labeled hyaluronate by 70%, whereas sulfated GAGs were not significantly increased. In dermis the incorporation of 3H-glucosamine into neither hyaluronate nor sulfated GAGs was stimulated by the retinoic acid. It is concluded that retinoic acid significantly modifies the differentiation of normal adult human epidermis by decreasing cytoskeleton components and by inducing the synthesis of new intercellular material, at least a part of which is hyaluronic acid. As a consequence, the cohesion between the epidermal cells was apparently weakened.

Chromatography, Thin Layer↗
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

A mutation that prevents glucosylation of the lipid-linked oligosaccharide precursor leads to underglycosylation of secreted yeast invertase.

A mutant of Saccharomyces cerevisiae with the genotype mnn1 mnn2 mnn9 gls1 synthesizes mannoproteins with oligosaccharides having the composition Glc3Man10Glc-NAc2- owing to the mnn9 defect, which prevents synthesis of the outer chain, the mnn1 defect, which prevents branching of the core, and the gls1 mutation, which prevents deglucosylation of the resultant glycoprotein as a consequence of a defective glucosidase-I [Tsai, P.-K., Ballou, L., Esmon, B., Schekman, R. & Ballou, C. E. (1984) Proc. Natl. Acad. Sci. USA 81, 6340-6343]. (The mnn2 defect is not expressed in presence of the mnn9 mutation.) This strain spontaneously forms new colonies in which gls1 is suppressed owing to a defect in synthesis of dolichol phosphoglucose, the glucosylation substrate. The new mutant, designated mnn1 mnn2 mnn9 gls1 dpg1, synthesizes and secretes invertase (EC 3.2.1.26) that has a higher mobility on native gel electrophoresis than that made by the parent strain, the consequence of a reduction in both the size and the number of carbohydrate chains. The mannoprotein chains have the mnn1 mnn9 structure (Man10Glc-NAc2-), and the invertase is resolved by gel electrophoresis in sodium dodecyl sulfate into two major and two minor bands that represent homologs with about 4-7 carbohydrate units, in contrast to about 8-11 chains in the parent strain. Thus, the inability to glucosylate the lipid-linked precursor reduces the efficiency of glycosylation of the protein chains. The genetic defect is in synthesis of the glucose donor dolichol phosphoglucose, but the mutation is nonallelic with the reported alg5-1 mutation, which has a similar phenotype [Runge, K. W., Huffaker, T. C. & Robbins, P. W. (1984) J. Biol. Chem. 259, 412-417].

Electrophoresis, Polyacrylamide Gel↗
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

Effects of retinoic acid on adult human epidermis in whole skin organ culture.

Adult human skin was cultured in whole-skin organ culture under chemically defined conditions. Retinoic acid was added to the culture at final concentrations of 5 X 10(-7) and 5 X 10(-6) M. Both concentrations elicited cell death in the upper epidermal layers and prevented the terminal differentiation of the cells to mature corneocytes. The inhibition of terminal differentiation was not permanent, as the corneocytes produced later during the culture showed no signs of inhibition. The upper vital cells in epidermis cultured with retinoic acid were very flattened and contained reduced amounts of cytoskeleton components. Fine, granular material not present in normal epidermis was observed in both the intercellular spaces and the intracytoplasmic vesicles of retinoid-treated epidermis. The present results indicate that the response of normal human skin to retinoic-acid treatment involves the same kind of modulation of the epidermal structure previously described in embryonic avian and diseased human skin.

Epidermis↗
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

Determination of unsaturated glycosaminoglycan disaccharides by spectrophotometry on thin-layer chromatographic plates.

Chondroitin sulfate isomers and hyaluronate, digested with chondroitinase AC II and separated as unsaturated disaccharides by thin-layer chromatography on cellulose, were quantitated with scanning spectrophotometry using reflectance measurement at 232 nm. The sensitivity of the assay was increased by one order of magnitude as compared to previous modifications of the disaccharide analysis on cellulose. The method allowed quantitation of 0.2-20 micrograms of glycosaminoglycan uronic acid. Since the elution of the disaccharides from the plate could be omitted, the speed and reproducibility of the assay was enhanced.

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↗