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Biomedical subjects

M Tammi

Publications and source records attributed to M Tammi.

At least 55 records · Page 3Linked to original sources
PubMed1997

CD44 substituted with heparan sulfate and endo-beta-galactosidase-sensitive oligosaccharides: a major proteoglycan in adult human epidermis.

CD44 is a group of cell surface glycoproteins that is generated from a single gene by mRNA splice variation. Its functions in matrix adhesion and tumor invasion are strongly influenced by glycosylation. We studied the glycosylated tissue forms of CD44 from extracts of normal adult human epidermis by using western blotting and immunoprecipitation from short-term skin organ cultures. An antibody for CD44 (Hermes 3) precipitated 7-17% of all 35SO4-labeled proteoglycans (PGs) synthesized in epidermis. Immunoprecipitates digested with heparitinase lost 40-68% of incorporated 35SO4 and 24-40% of [3H]glucosamine, indicating that heparan sulfate was the predominant glycosaminoglycan in epidermal CD44. Chondroitinase ABC released 10-25% and 6-12% of 35SO4 and [3H]glucosamine, respectively. Less than 5% of both isotopes were susceptible to keratanase. Five to 33% of 35SO4 and 26-37% of [3H]glucosamine, however, was released by endo-beta-galactosidase, implying marked substitution by oligosaccharides with N-acetyllactosamine repeats. Heparitinase pretreatment retarded, whereas endo-beta-galactosidase enhanced the mobility of the > or = 180-kDa polydisperse CD44 on agarose gel electrophoresis. On SDS-polyacrylamide gel electrophoresis, however, western blotting and fluorographs of 35SO4-labeled immunoprecipitates showed the main CD44 isoform at > or = 250 kDa and a shift to 180-200 kDa after heparitinase treatment. Keratanase, keratanase II, and chondroitinase ABC had minor effects. A less abundant form of CD44, with a core of 100 kDa, partly substituted with chondroitinase ABC- and endo-beta-galactosidase-sensitive chains, was also present. Therefore, the large heparan sulfate-substituted CD44 forms a significant part of all proteoglycans in normal human epidermis. Both the large and the 100-kDa variant of epidermal CD44 contain endo-beta-galactosidase-sensitive oligosaccharides not previously noted in other cells or tissues.

Adult↗
PubMed1997

Developmentally programmed expression of hyaluronan in human skin and its appendages.

The expression of hyaluronan (HA) in fetal human skin was studied by using a biotinylated HA-binding probe. The uniform expression of HA in primitive skin was changed after the 9th week, when differentiation of the basement membrane zone increased HA in the subepidermal mesenchyme. Maturation of the papillary dermis at the 12-20th weeks led to the thickening of this HA-enriched zone; the underlying reticular layer was less intensely stained. In epidermis the number of cell layers rapidly increased after the 9th week. At first all epidermal layers were HA-positive. A complete loss of HA from the upper intermediate cells on the 18th week preceded the formation of mature granular and cornified layers. Peridermal cells remained HA-positive even when the underlying stratum corneum turned negative. The tightly apposed basal epithelial cells, the first stage of hair follicle and eccrine sweat gland formation, became almost completely depleted of HA. With advancing bulb development HA returned in the epithelial compartment, until maturation of the hair follicles restricted its expression to the outer root sheath and hair matrix. Maturation of the sebaceous glands led to the expression of HA pericellularly in the germinative cells and intracellularly in the mature sebocytes. Marked changes thus occur in the distribution of HA during fetal skin development; the primitive tissues exhibited a uniform widespread expression of HA, and maturing tissues showed distinct locally regulated patterns. The loss of epithelial HA in the hair follicle anlagen and upper intermediate cells turned out to be early differentiation markers.

Cell Differentiation↗
PubMed1996

Spatial distribution of CD44 and hyaluronan in the proximal tibia of the growing rat.

CD44 has been described as a cell surface hyaluronan receptor present on a variety of different cells, and it is generally assumed to be prevalent in most connective tissues that contain hyaluronan. A major aim of this study was to test that presumption by localizing CD44 and hyaluronan within several tissues of the proximal tibia of the growing rat. Comparison of these profiles would reveal whether CD44 and hyaluronan co-localize with high fidelity, as would be expected if CD44 were a major hyaluronan binding protein. Using in situ hybridization and immunohistochemistry, CD44 was identified on osteoclasts, chondroclasts, osteocytes, hematopoietic marrow cells, synovial cells, and connective tissue fibroblasts (ligaments, tendons, and fascia). Although the majority of osteocytes expressed CD44, reduced expression was observed for osteoblasts and ostcoprogenitor cells. Additionally. CD44 was not detected on chondrocytes from epiphyseal and metaphyseal growth cartilages or in meniscal fibrocartilage. Using biotinylated G1 domain from aggrecan and link protein, hyaluronan was observed in the maturational and hypertrophic zones of all growth cartilages, the synovium and other fibroblastic connective tissues, regional areas of the periosteum and endosteum (around osteoblasts, osteoprogenitor cells, and osteoclasts), osteocyte lacunae, and surrounding blood vessels. In regions of co-localization for CD44 and hyaluronan, it seems that CD44 is a likely hyaluronan binding protein in several tissues of the proximal tibia. However, it does not appear to be the predominant hyaluronan binding protein in growing cartilages of the weanling rat.

Aggrecans↗
PubMed1996

Safranin O reduces loss of glycosaminoglycans from bovine articular cartilage during histological specimen preparation.

The ability of Safranin O, added to fixation and decalcification solutions, to prevent the escape of glycosaminoglycans (GAGs) from small cartilage tissue blocks during histological processing of cartilage has been studied. GAGs in the fixatives and decalcifying solutions used and those remaining in the 1 mm3 cubes of cartilage were assayed biochemically. The quantity of GAGs remaining in the cartilage cubes were determined from Safranin O-stained sections using videomicroscopy or microspectrophotometry. A quantity (10.6%) of GAGs were lost during a conventional 4% buffered formaldehyde fixation (48 h) and a subsequent decalcification in 10% EDTA (12 days) at 4 degrees C. Roughly one-quarter of the total GAG loss occurred during the 48 h fixation, and three-quarters during the 12 days of decalcification. Inclusion of 4% formaldehyde in the decalcification fluid decreased the loss of GAGs to 6.2%. The presence of 0.5% Safranin O in the fixative reduced this loss to 3.4%. When 0.5% Safranin O was included in the fixative and 4% formaldehyde in the decalcification solution, Safranin O staining of the histological sections increased on average by 13.5%. After fixation in the presence of 0.5% Safranin O, there was no difference in the staining intensities when decalcification was carried out in the presence of either Safranin O or formaldehyde, or both. It took 24 h for Safranin O to penetrate into the deep zone of articular cartilage, warranting a fixation period of at least this long. In conclusion, the addition of Safranin O to the fixative and either Safranin O or formaldehyde in the following decalcification fluid, markedly reduces the loss of GAGs from small articular cartilage explants during histological processing. However, for immunohistochemical studies, Safranin O cannot be included in the processing solutions, because it may interfere.

Animals↗
PubMed1996

Hyaluronan distribution in the normal epithelium of esophagus, stomach, and colon and their cancers.

The distribution of hyaluronan (HA) in normal gastrointestinal wall and in tumors originating from their epithelium was studied using a specific probe prepared from cartilage proteoglycan (bHABC, biotinylated hyaluronan binding complex). The normal stratified squamous epithelium of esophagus showed an intense HA staining in the basal and lower intermediate layers, whereas the simple epithelia in the stomach and large intestine were HA negative. Esophageal in situ carcinomas expressed HA also in the cell layers close to the luminal surface, in regions normally negative. Most of the invasive squamous cell carcinomas maintained their HA expression, but in very poorly differentiated types the tumor parenchyma was devoid of HA. In both gastric and colonic adenocarcinomas the tumor parenchyma showed no HA. The stromal tissue was intensely HA positive in all tumors. Cancer cells invading the intestinal smooth muscle were surrounded by copious amounts of HA, whereas the muscular layer was otherwise very poor in HA staining. These results show that relatively well differentiated carcinoma cells themselves retain the high or low HA expression pattern of their original epithelium, whereas tumors stimulate HA deposition in the surrounding stroma.

Colon↗
PubMed1995

Hydrocortisone regulation of hyaluronan metabolism in human skin organ culture.

We studied the influence of hydrocortisone (HC) on hyaluronan (HA) metabolism in explants of human skin, a model retaining normal three-dimensional architecture of dermal connective tissue and dynamic growth and stratification of epidermal keratinocytes. The synthesis of hyaluronan and proteoglycans (PGs), and DNA, were determined with 3H-glucosamine and 3H-thymidine labelings, respectively. The total content and histological distribution of hyaluronan was studied utilizing a biotinylated aggrecan-link protein complex. A low concentration of HC (10(-9) M) stimulated the incorporation of 3H-glucosamine into hyaluronan in epidermis by 23% and reduced the disappearance rate of hyaluronan by 25% in chase experiments, resulting in a 74% increase in total hyaluronan (per epidermal dry weight) after a 5-day culture in 10(-9) M HC. On the other hand, a high concentration of HC (10(-5) M) reduced both synthesis (-42%) and degradation (-46%) of epidermal hyaluronan during 24 h labeling and chase periods. The cumulative effect of a 5-day treatment was a 24% decrease of total epidermal hyaluronan. The high dose (10(-5) M) also reduced keratinocyte DNA synthesis and epidermal thickness. In dermis, only the high (10(-5) M) concentration of HC was effective, inhibiting the incorporation of 3H-glucosamine into hyaluronan by 28%. No significant influences on total hyaluronan content or the disappearance rate of hyaluronan in dermal tissue was found. All HC concentrations lacked significant effects on newly synthesized PGs in epidermal and dermal tissues, but reduced the labeled PGs diffusing into culture medium. A low physiological concentration of HC thus maintains active synthesis and high concentration of hyaluronan in epidermal tissue, while high pharmacological doses of HC slows hyaluronan turnover and reduces its content in epidermis, an effect correlated with enhanced terminal differentiation, reduced proliferation rate and reduced number of vital keratinocyte layers.

Cell Division↗
PubMed1995

Influence of short-term hydrostatic pressure on organization of stress fibers in cultured chondrocytes.

The present study describes changes in the organization of stress fibers that occur in articular cartilage chondrocytes subjected to hydrostatic pressure. Primary cultures of chondrocytes from bovine articular cartilage, grown on coverslips, were subjected to 5, 15, or 30 MPa hydrostatic pressure at 37 degrees C. The pressure was applied continuously or cyclically at two frequencies: 0.125 Hz (4 seconds of pressure and 4 seconds of no pressure) or 0.05 Hz (1 second of pressure and 19 seconds of no pressure) for a period of 2 hours. Control chondrocytes showed a polygonal form with prominent stress fibers extending across the cells. The exposure of cells to 30 MPa pressure caused a nearly total disappearance of stress fibers and retraction of the cells from each other. With pressure at 15 MPa or cyclic pressure, the number of cells with stress fibers was decreased. In cells subjected to 5 MPa pressure, the stress fibers resembled those in control chondrocytes. The pressure effects were reversible after 2 hours. Pressure had no effect on the staining pattern of vinculin, which suggests that microfilaments are more vulnerable to pressure than vinculin. The results indicate that cytoskeletal changes may be an integral part of the response of chondrocytes to hydrostatic pressure.

Animals↗
PubMed1995

Long-distance running alters bone anthropometry, elemental composition and mineral density of young dogs.

Ten young beagle dogs were run on a treadmill for 1 year, the last 15 weeks 40 km/day. Thereafter bone anthropometric variables, elemental composition, mineral density (BMD) and serum markers of bone metabolism were analyzed and compared with matched-paired control dogs. More osteophytes developed, weight-bearing bones grew larger and BMD of axial skeleton was reduced in the trained group. Zinc and sodium accumulated in bones of the runners. Zinc correlated negatively with BMD. Serum osteocalcin and C-terminal propeptide of type I procollagen did not correlate with the observed differences in BMD. This experiment implies that intensive endurance training in adolescence may reduce the peak bone mass and alter the structural properties of bone.

Animals↗
PubMed1995

Proteoglycan depletion and size reduction in lesions of early grade chondromalacia of the patella.

OBJECTIVE: To determine the content and molecular size of proteoglycans (PGs) in patellar chondromalacia (CM) and control cartilages as a first step in investigating the role of matrix alterations in the pathogenesis of this disease. METHODS: Chondromalacia tissue from 10 patients was removed with a surgical knife. Using identical techniques, apparently healthy cartilage of the same site was obtained from 10 age matched cadavers (mean age 31 years in both groups). Additional pathological cartilage was collected from 67 patients with grades II-IV CM (classified according to Outerbridge) using a motorised shaver under arthroscopic control. The shaved cartilage chips were collected with a dense net from the irrigation fluid of the shaver. The content of tissue PGs was determined by Safranin O precipitation or uronic acid content, and the molecular size by mobility on agarose gel electrophoresis. RESULTS: The mean PG content of the CM tissue samples with a knife was dramatically reduced, being only 15% of that in controls. The cartilage chips collected from shaving operations of grades II, III, and IV CM showed a decreasing PG content: 9%, 5%, and 1% of controls, respectively. Electrophoretic analysis of PGs extracted with guanidium chloride from the shaved tissue samples suggested a significantly reduced size of aggrecans in the mild (grade II) lesions. CONCLUSION: These data show that there is already a dramatic and progressive depletion of PGs in CM grade II lesions. This explains the softening of cartilage, a typical finding in the arthroscopic examination of CM. The PG size reduction observed in grade II implicates proteolytic attack as a factor in the pathogenesis of CM.

Adult↗
PubMed1994

Articular cartilage thickness and glycosaminoglycan distribution in the young canine knee joint after remobilization of the immobilized limb.

The recovery of articular cartilage from atrophy induced by joint immobilization was investigated in immature dogs. In a previous study, we showed that 11 weeks of immobilization of the knee (stifle) joint of young dogs reduced the concentration of articular cartilage glycosaminoglycans (GAGs) by 13-47%. In the present study, right hindlimbs from six female beagles were immobilized for 11 weeks, as in the previous study, and then were remobilized for 15 weeks. Cartilage from the knee joint was compared with cartilage from nonimmobilized knees of eight age-matched control beagles. Histological samples taken from 11 different locations of the knee joint were stained with safranin O, and microspectrophotometry was used to demonstrate distribution of GAGs in the tissue. After remobilization, GAG concentration was restored in the patellofemoral region and tibial condyles. On the summits of the femoral condyles, and especially at the periphery of the femoral condyles, GAG concentration remained 8-26% less than the control values. On the summits, the thickness of the uncalcified cartilage was as much as 15% less than in the age-matched controls. Consequently, the changes induced by unloading were reversible to a great extent, but a full restoration of articular cartilage was not obtained at all sites of the knee joint within the 15 weeks of remobilization. Immobilization of the skeletally immature joint therefore may affect the development of articular cartilage in such a way that very slow recovery or permanent alterations are induced.

Animals↗
PubMed1994

A dot-blot assay of metabolically radiolabeled hyaluronan.

Glycosaminoglycans labeled in tissue culture in the presence of [3H]glucosamine were proteolytically solubilized and then precipitated with cetylpyridinium chloride onto a sheet of nitrocellulose using a dot-blot apparatus. The proportion of hyaluronan (HA) was calculated from parallel aliquots digested with Streptomyces hyaluronidase, an enzyme specifically degrading HA. A linear response of radioactivity was obtained for samples in the range of 50-10,000 cpm (1-1000 ng total HA) when the dots cut from the membrane were counted with liquid scintillation. Negligible interference from an excess of unincorporated precursor, chondroitin sulfate, and proteolytic tissue digest was observed. The assay was particularly convenient in measuring large numbers of samples with relatively low activity, such as testing the effects of different drug concentrations and analyzing chromatographic fractions.

Cetylpyridinium↗
PubMed1994

Hyaluronan and CD44 in psoriatic skin. Intense staining for hyaluronan on dermal capillary loops and reduced expression of CD44 and hyaluronan in keratinocyte-leukocyte interfaces.

The distributions of hyaluronan (HA) and its presumptive receptor, CD44, were studied in skin samples from 13 psoriasis vulgaris patients, using an HA-specific probe (HABC), and monoclonal antibodies, respectively. The general distribution of HA and CD44 in psoriatic lesional epidermis resembled that in normal epidermis. However, areas of epidermis invaded by leukocytes showed a local depletion of HA and CD44, particularly at the contact areas of keratinocytes to lymphocytes and neutrophils. Removal by cellular uptake or extracellular degradation of CD44 and HA may be required for tight adherence between a keratinocyte and a leukocyte. On the dermal side, the tips of the prolonged dermal papillae in psoriatic lesions were intensively stained with HABC. The dilated capillaries and the space below the tip basal lamina, in particular, were heavily covered with HA. Occasionally, a similar intense staining was seen around an enlarged capillary in uninvolved psoriatic skin. CD44-positive leukocytes were found around the affected capillaries. The accumulation of HA in the dermal papillae may support the growth of psoriatic lesions, since HA stimulates the growth of capillaries as well as attracting inflammatory cells.

Adult↗
PubMed1994

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)

Animals↗
PubMed1994

Softening of the lateral condyle articular cartilage in the canine knee joint after long distance (up to 40 km/day) running training lasting one year.

The effects of long distance running training (up to 40km/day) on the biomechanical properties of young canine articular cartilage were investigated using in situ indentation creep technique. The stiffness of articular cartilage was determined in the form of instantaneous and equilibrium shear moduli. The rate of cartilage deformation was also computed. Microspectrophotometric and polarized light microscopic analyses were made for determination of local glycosaminoglycan content and collagen organization, respectively. During a period of one year, the runner dogs (n = 10) underwent a gradually increased treadmill exercise up to 40 km/day, while the littermate control dogs (n = 10) lived normally in their cages. The equilibrium shear modulus of articular cartilage decreased significantly by 12 to 14% (p < 0.05) in the lateral, but not in the medial, condyles of femur and tibia. In the lateral condyles of the runner dogs, the deformation rate of cartilage increased by 16% (p < 0.05). Consequently, the articular cartilage response to running training was site-dependent. The simultaneous changes of the equilibrium shear modulus or the retardation time spectrum and the glycosaminoglycan content confirm the key role of proteoglycans in modulating the cartilage equilibrium stiffness and creep rate. The changes in the instant shear modulus appeared to be predominantly related to the alterations in the organization of the superficial collagen network. Although the running training did not create cartilage damage, we assume that the softening of the cartilage may with time jeopardize the ability of articular cartilage to maintain its normal structural and functional properties.

Animals↗
PubMed1994

Distribution of hyaluronan in bull reproductive organs.

To study the expression of hyaluronan in male reproductive organs and the origin of seminal plasma hyaluronan, we stained various parts of the bull reproductive tract for hyaluronan using a biotinylated probe derived from cartilage proteoglycan (bHABC). The potential loss of hyaluronan during tissue processing was checked with a novel technique by blotting frozen tissue sections on nitrocellulose and staining the blots with bHABC. In the same tissues the CD44 receptor was visualized by Hermes 1 antibody. The testes showed only traces of hyaluronan, whereas both the epithelium and the connective tissue of seminal vesicle, prostate, Cowper's gland, and epididymis were positive in bHABC staining. Hyaluronan was localized on the basolateral surfaces of these epithelial cells. The secretions inside the seminal vesicle and in the ducts of prostate and Cowper's gland were HA-positive, whereas the luminal contents of seminiferous tubules and epididymis were unstained both in paraffin sections and in the in situ blocks. The data indicate that hyaluronan in seminal plasma originates from the accessory sex glands. The co-localization of CD44 with hyaluronan in the basolateral surfaces of the accessory gland epithelia and its absence from other epithelia with little or no hyaluronan supports its role as a hyaluronan receptor.

Animals↗
PubMed1994

Proteoglycan and collagen alterations in canine knee articular cartilage following 20 km daily running exercise for 15 weeks.

The composition of extracellular matrix was studied at 11 different sites in the knee (stifle) articular cartilage of young beagle dogs after running exercise of 15 weeks, 20 km/day. Water content was significantly elevated by 5-17% in the patellofemoral groove and in anterior and intermediate sites on the lateral condyle of femur. Collagen content was decreased by 14 to 20% in the same sites of the lateral condyle. Proteoglycan (PG) content was not significantly changed except in the posterior edge of the medial condyle of femur with a 30% decrease. The proportion of PGs capable of reaggregation with hyaluronan was increased in tibial and femoral surfaces (mean of all sites +18%). Also, the aggregating PG monomers were larger at all sites, as studied by agarose gel electrophoresis. The chondroitin-6 to 4-sulphate ratio was reduced at the summits of femoral condyles and patella by 10 to 25%, but increased in the patellar surface of femur and tibial medial condyle, fitting to a previous finding that strenuous running depleted proteoglycans at the summits of femoral condyle from the superficial zone that is rich in chondroitin-6-sulphate. The increased water content, accompanied with a decreased concentration of collagen in the lateral femoral condyle, suggests loosening of the collagenous framework, an idea compatible with an earlier notion of superficial depletion of PGs in these sites, and possibly predisposing to degeneration. The size increase of the aggregating PGs probably indicate that a larger proportion of matrix PGs were newly synthesized and hence the turnover rate of the PGs was enhanced. It is concluded that the strenuous running program induced locally restricted changes resembling early degeneration of articular cartilage, while simultaneously caused alterations that suggest a general stimulation of proteoglycan metabolism.

Animals↗