Biomedical subjects

E Livne

Publications and source records attributed to E Livne.

At least 55 records · Page 3Linked to original sources

PubMed1989

Biochemical characterization of a virus-induced osteosarcoma-like osseous lesion in vitro.

Chondroprogenitor cells present in the apical and lateral parts of the mandibular condyle from neonatal mice differentiate towards the osteoblastic lineage and form bone within 7 days in culture. Infection of condylar explants with the FBR osteosarcoma virus (FBR MSV) results in the transformation of cells in the progenitor zone, previously identified as the target for the virus, and the formation of a transplantable osteosarcoma-like lesion. Morphological and biochemical changes in this system were investigated in the course of tumor development. Virus infection was followed by a significant increase in cell density and 3H-thymidine incorporation within the progenitor zone at the early stage of culture. In later stages, cell density and 3H-thymidine incorporation were lower than in control tissue. The 3H-thymidine labeling index gave similar results in infected and control tissues until day 7. Then, a significantly higher labeling index was found in the progenitor zone of infected condyles. At this stage, the proliferative effect of the virus even affected the cartilagenous core of the tissue. Quantitative alkaline phosphatase activity increased between day 3 and day 7 and was particularly high in the zone of infected cells. In addition, infected tissues consistently revealed a higher uptake of 45Ca, and deposition of the radioisotope along irregularly formed bone trabecules in the transformed tissue. The results suggest that there is an enhancement of tissue maturation following infection with the FBR osteosarcoma virus. Although biochemical investigations of whole condyles showed few differences in the total values of alkaline phosphatase activity, 3H-thymidine incorporation, DNA content, and 45Ca uptake, the histochemical assays revealed clear differences in the distributional pattern of these parameters within infected and control condyles.

Alkaline Phosphatase↗

PubMed1989

Effects of leukemogenic retroviruses on condylar cartilage in vitro: an ultrastructural study.

Mandibular condyles of late embryonic NMRI mice were used in an in vitro organ culture system to study the effect of bone tumor-derived murine leukemia viruses OS-5 MuLV and OA MuLV known to induce osteopetrosis and osteomas. Skeletal precursor cells present in the condylar tissue normally undergo rapid differentiation in vitro which results in new bone formation. The infection of condyles with either OS-5 MuLV or OA MuLV markedly interfered with the normal developmental pattern of the organ leading to the formation of an atypical, heavily mineralized tissue. Many spindlelike cells and pleomorphic cells were encountered, whereas fibroblastlike cells were found to penetrate an underlying collagen substratum. These observations indicate that bone tumor-inducing leukemogenic retroviruses directly affect cartilage and/or bone precursor cells resulting in pathologic developments in the skeleton.

Animals↗

PubMed1988

Growth and repair of cartilage: organ culture system utilizing chondroprogenitor cells of condylar cartilage in newborn mice.

The zone of progenitor cells of mandibular condyles of neonatal mice was kept in an organ culture system for up to 8 days. Qualitative and quantitative determinations indicated a pronounced proliferative activity during the initial phases of the culture followed by a differentiation phase and the acquisition of typical hyaline cartilage. The mature hypertrophic chondrocytes were found to be surrounded by cartilage-specific macromolecules such as type II collagen, cartilage proteoglycans, and cartilage anchorin. The extracellular mineralization proceeded along matrix vesicles as is usually noted in vivo. A unique finding in this study was the observation that explants comprising cartilage progenitor cells and their adjacent extracellular matrix succeeded in repairing the damaged condylar in vitro.

Animals↗

PubMed1988

Triamcinolone impairs the synthesis of collagen and noncollagen proteins in condylar cartilage of newborn mice.

The effects of triamcinolone hexacetonide (TH) on the synthesis of collagen and noncollagen proteins were tested in mandibular condylar cartilage of newborn mice. Four-day-old ICR mice received a single i.p. injection of TH at doses ranging from 0.4 to 4.0 mg/kg body weight. Hydrocortisone, deoxycorticosterone, dexamethasone, and progesterone were administered at a dose of 4.0 mg/kg. Test animals and nontreated and vehicle-treated controls were sacrificed after 24, 48, and 72 hours and were processed for electron microscopy. Additional animals were injected with 5 microCi of 3H-proline 2 hours before sacrifice. The specimens were extracted with 5% TCA containing 1 mM proline followed by 5% TCA, acetone, and ether, homogenized and digested with purified bacterial collagenase, and the amounts of radioactivity in collagenase digestible (CDP) and noncollagen proteins (NCP) were determined. The present results revealed that triamcinolone led to a significant dose-dependent decrease in the protein content of the tissue that lasted for 3 days (12-14% at the dose of 4 mg/kg). The incorporation of 3H-proline into CDP was reduced by 39, 57, and 42% at 24, 48, and 72 hours, respectively whereas the incorporation into NCP was reduced by 20, 35, and 23%, respectively. When compared with other steroids, dexamethasone revealed a similar inhibitory effect, whereas hydrocortisone and deoxycorticosterone had no significant effect. Progesterone, on the other hand, showed a transient (24 hours) stimulatory effect on the synthesis of collagen synthesis (21%, P less than 0.05). Electron microscopy showed an atypical arrangement of collagen fibers and accumulation of large aggregates of collagen that filled the entire matrical space between cartilage cells.

Adrenal Cortex Hormones↗

PubMed1988

Differentiation of cartilage cells studied by quantitative [3H]thymidine autoradiography in vitro.

The apical segments of the mandibular condylar cartilage of newborn ICR mice, containing the intact zones of progenitor cells along with a few rows of chondroblasts were initially prelabelled in vitro with [3H]thymidine and were subsequently chased and cultured for as long as eight days. Such explants underwent a process of tissue regeneration, as after three days in culture they reconstituted the original structure of the organ, thus resembling the in vivo appearance of neonatal mandibular condylar cartilage. Cellular proliferation with subsequent differentiation in the regenerating tissue was followed by means of quantitative autoradiography. Immediately after labelling, the autoradiography-positive grains were confined exclusively to progenitor cells. The latter revealed a substantial ability to proliferate in vitro, a fact that was manifested by a progressive increase in the labelling index along the course of the culture. The latter process was followed by cellular differentiation thereby obtaining hypertrophic chondrocytes. The increase in the rate of labelling index and in the total number of [3H]thymidine-labelled cells was significantly correlated with the overall growth of the regenerating explants.

Animals↗

PubMed1988

Enhancing effects of fluoride-containing ceramic implants on bone formation in the dog femur.

This study examined the enhancing effects of newly constructed ceramic implants, consisting of unidirectional macroporous (200 micron in diameter) material, upon in vivo bone formation in dogs' femurs. The implants comprised calcium phosphate salts that included 0.5% fluoride. The latter were introduced into bone defects in healthy dogs and were followed thereafter for a period of 8 months. Radiological and histological examinations indicated new bone formation at the implantation sites concurrent with the disappearance of the original implanted material. The rate of in situ degradation of these implants correlated to the overall size of the inserted implant. It became evident that this new kind of ceramic (that included fluoride in its basic composition) possessed a remarkable stimulating potential upon bone morphogenesis.

Animals↗

PubMed1988

Picrotoxin, a gamma-aminobutyric acid-receptor antagonist, retards craniofacial development in the weaning rat: I. Effect on mandibular bone growth.

The in vivo effects of elevated doses of picrotoxin, a gamma-aminobutyric acid (GABA) A-receptor antagonist, were studied in the skulls of weaning rats. Twenty-one-day-old male rats were treated daily with 2 mg/kg of pictroxin for a period of 3 weeks. This study revealed that chronic administration of the agent caused a reduction in bone formation in various growth sites in the skull along with a significant decrease in the calcium content and alkaline phosphatase activity in the mandible. Serum levels of calcium were unchanged, but the activity of alkaline phosphatase decreased. The decrease in bone alkaline phosphatase was accompanied by structural changes in the developing mandible. The latter was manifested by qualitative changes in the structure of ossification sites, in the appearance of the osteoblasts, and in the pattern of bone mineralization. These findings indicate that picrotoxin affects the normal growth of the craniofacial skeleton in an intact growing animal, probably because of central changes in GABA-ergic control on motor function along with possible alteration in corticosteroid secretion.

Alkaline Phosphatase↗

PubMed1988

Picrotoxin, a gamma-aminobutyric acid-receptor antagonist, retards craniofacial development in the weaning rat: II. Effect on mandibular condylar cartilage.

The in vivo effects of picrotoxin, a gamma-aminobutyric acid (GABA)-receptor antagonist, were studied in the mandibular condyles of weaning rats. Male rats 21 days old were treated daily with 2 mg/kg of picrotoxin for a period of 3 weeks. This study revealed that chronic administration of the agent caused a reduction in bone formation in various sites in the mandible, along with significant changes in the structure of the condylar cartilage and its ossification front. The length of the chondroblastic zone increased, yet the length of the hypertrophic zone was reduced. The latter phenomenon was manifested by qualitative changes in the overall structure of various cellular zones, in the appearance of the osteoblasts, and in the pattern of cartilage mineralization. The changes in the condylar cartilage cannot be attributed to a direct effect of picrotoxin; in vitro studies indicated no significant change in the incorporation of 3H-thymidine and 35S-sulfate in picrotoxin-treated cultures. These findings indicate that picrotoxin affects the normal growth of the mandible in an intact, growing animal, probably through an indirect route involving neurons in the central nervous system.

Animals↗

PubMed1988

Glucocorticoid hormone adversely affects the growth and regeneration of cartilage in vitro.

Apical portion of condylar cartilage of neonatal mice served as an experimental model to study the in vitro effects of elevated concentration of triamcinolone, a fluorinated synthetic analogue of cortisol on cartilage cell growth and development. Triamcinolone acetonide (10(-6) M) led to a significant decrease in the proliferative rate of chondroprogenitor cells along with an inhibition of the chondrogenic differentiation pathway. By 5 days in culture, control explants exhibited a pronounced increase in size and succeeded to reconstitute their native form. In hormone-treated cultures, the explants also elongated yet the increase was due to an accelerated cellular hypertrophy rather than increase in cell number. The findings of the present study which were based upon quantitative 3H-thymidine autoradiography as well as upon determination of 3H-thymidine incorporation suggest that in vitro corticosteroid hormone depresses pre-chondroblasts proliferation along with an interference in the normal differentiative pathway of the above cells.

Animals↗

PubMed1987

In vitro induction of osteosarcomalike lesion by transformation of differentiating skeletal precursor cells with FBR murine osteosarcoma virus.

This study analyzed the transforming potential of murine viruses in organ cultures of mouse fetal condylar cartilage: Finkel-Biskis-Jinkins-Murine sarcoma virus (FBJ-MuSV) and Finkel-Biskis-Reilly-Murine sarcoma virus (FBR-MuSV). It was only the FBR-MuSV isolated from a radiation-induced osteosarcoma, that induced morphological changes as early as 24 hours following the infection. The latter manifested itself by a marked enlargement of the number of progenitor cells concomitant with an accumulation of spindle-like cells, giant cells, and pleomorphic cells along with large bone spicules and heavy mineralization of the remaining cartilage. The newly formed tissue synthesized type I collagen and revealed profound invasive characteristics. By day 7, FBR-MuSV-infected cultures acquired the appearance of an osteosarcomatouslike lesion. Electron microscopy examinations revealed that both the matrix and the osteogenic cells in the induced tumors differed markedly from that encountered in normal mammalian osseous tissue. To determine which cells within the condylar tissue served as the target for the FBR-MuSV, we used antibodies against viral P30 protein for an indirect immunoperoxidase reaction. The chondroprogenitor cells were the only ones that reacted positively for the virus-specific protein. Further, the in vitro-induced tumor was tumorigenic in syngeneic mice, hence, brought about the development of osteo-fibrosarcoma subcutaneously. By contrast to FBR-MuSV, the FBJ-MuSV did not elicit similar transformative effects in vitro. Since both viruses possess the fos oncogene, it has been suggested that the unique tumorigenic potential of the FBR-MuSV may be linked to structural alterations in the fos oncogene product.

Animals↗

PubMed1987

The in vitro behavior of fetal condylar cartilage in serum-free hormone-supplemented medium.

Mandibular condyles of fetal mice 19-20 days in utero were kept in a serum-free organ culture system for up to 14 days and were investigated for their capacity to develop osteoid and to mineralize in vitro. After 3 days in culture, the cartilage of the mandibular condyle appeared to have maintained all its inherent structural characteristics, including its various cell layers: chondroprogenitor, chondroblastic, and hypertrophic. After 7-9 days in culture, no chondroblasts could be seen; instead, most of the cartilage consisted of hypertrophic chondrocytes. In addition, various areas throughout the explant revealed the appearance of osteoidlike material. The process of matrix mineralization progressed with time, and by the 14th day new bonelike material was found to occupy a larger portion of the explant. The newly formed matrix reacted positively with antibodies against type I and type III collagens, as well as against bone alkaline phosphatase. Electron microscopic examination showed that the mineralization appeared to be associated with collagen fibers as well as the matrix vesicles. In composition, the in vitro-formed mineral deposits resembled hydroxyapatite crystals. Biochemical assays indicated that the newly formed tissue reacted strongly for alkaline phosphatase and incorporated 45Ca. The findings of the present study imply that fetal condylar cartilage possesses the potential to develop in vitro osseouslike tissue even in a system that is serum-free. Due to the fact that the newly formed extracellular matrix mineralized and reacted positively to bone markers as well as to cartilage macromolecules, it would seem justifiable to define the new tissue as chondroid bone.

Alkaline Phosphatase↗

PubMed1987

Further characterization of the chondroprogenitor zone in mandibular condyles of suckling mice. An ultrastructural and cytochemical study.

In the neonatal mouse the mandibular condyle serves as an important growth center for the developing mandible. The youngest cells in this organ are the chondroprogenitor cells that are the source for new differentiating chondroblasts. The present study provides new data concerning the fine structure and cytochemical characteristics of the cartilage precursor cells as seen in suckling mice. The condylar chondroprogenitor cells normally reveal a mesenchyme-like appearance with multiple, elongated cell processes that enable close contact between neighboring cells. These cells also exhibit a variety of pinocytotic vesicles, coated pits and appear to be actively involved in the internalization of a fluid-phase marker horseradish peroxidase. Further, the progenitor cells were found to contain trimetaphosphatase reaction products within lysosomal bodies and alkaline phosphatase reactivity along their plasma membrane. Precipitates of calcium complexes in the form of calcium pyroantimonate could be demonstrated in association with the plasmalemma of the cells as well as with the extracellular collagen fibrils. Matrix granules, representing cartilage proteoglycans, became a distinct feature following staining with ruthenium red and were found to be in close contact with the extracellular collagen fibrils and with the plasmalemma. Hence, in addition to their active role in cell proliferation, the progenitor cells are also involved in the synthesis and secretion of major extracellular macromolecules such as collagen and proteoglycans.

Acid Anhydride Hydrolases↗

PubMed1987

Age-related changes in the role of matrix vesicles in the mandibular condylar cartilage.

A combined approach of light microscopy, immunofluorescence, transmission electron microscopy and electron energy loss spectroscopy (EELS) was used to study age-related changes in the condylar cartilage in mice. Chondrocalcin, a cartilage matrix calcium-binding protein, was demonstrated by indirect immunofluorescence microscopy using monospecific antibodies. In one week old animals the most intense staining was observed in the matrix around the hypertrophic cells in the mineralising zone, to a lesser degree around the cells in the zone of chondroblasts, while no staining was noted in the zone of chondroprogenitor cells and in the matrix around the early hypertrophic cells. In the mineralisation zone the distribution of chondrocalcin correlated with that of mineral deposits as revealed by the von Kossa stain. The matrix between the early hypertrophic cells as shown by transmission electron microscopy revealed the presence of matrix vesicles and demonstrated a gradual accumulation of hydroxyapatite in the mineralising zone. In one month old animals chondrocalcin localisation was mainly confined to the lower hypertrophic zone which also demonstrated positive von Kossa staining was seen along the articular surface. In older animals multiple electron-dense structure that resembled matrix vesicles were observed in the non-mineralising portions of the condylar cartilage. Use of the EELS method confirmed the almost complete lack of calcium ions in these structures. In contrast, with the use of the same method, detectable amounts of calcium were recorded in vesicles in the mineralising zones of all age groups. Hence what appear ultrastructurally as structures similar to matrix vesicles represent atypical vesicles that might characterise an ageing and degenerative articular cartilage and are not necessarily associated with the mineralisation process.

Aging↗

PubMed1986

Structural and metabolic changes characterizing the aging of various cartilages in mice.

It is well documented that various organs and tissues in the body show a differential, non-homogeneous pattern of development and aging. The present study evaluates some of the morphological and metabolic changes characterizing the aging of different types of cartilages in normal male mice. Representatives of hyaline, fibrous, articular and elastic types of cartilage were obtained from animals ranging from 1 week to 1 year of age. Our determinations included the following: total body and organ weights, proteins and DNA concentrations, [3H]leucine and [35S]sulfate uptake. The biochemical assays were accompanied by morphological examinations of corresponding tissue specimens. This investigation clearly indicates that the growth and maturational activities of the various cartilages examined attained their completion at a very early stage of life (1-3 months postnatally). Thereafter, a phase of steady state prevails, followed by a gradual but continuous decline in the various metabolic activities. The morphological findings illustrate the nature of the age-related structural changes. The present findings indicate that a skeletal tissue such as cartilages of various types, tends to age early during the lifespan of the animal.

Aging↗

PubMed1986

Internalization of cationized ferritin by isolated pancreatic acinar cells.

The internalization of cationized ferritin (CF) was studied in isolated pancreatic acinar cells in vitro. Horseradish peroxidase (HRP) was used in conjunction with CF to compare internalization of soluble-phase and membrane-bound tracers. The mode of internalization of CF was dependent upon tracer concentration and origin of the plasma membrane (apical vs. lateral-basal). At the lower tracer concentrations (0.19 and 0.38 mg/ml), internalization from the apical cell surface occurred via small vesicles. The tracer then appeared in multivesicular bodies, in tubules, and in irregular membrane-bound structures. After 15 min, CF particles were seen in many small vesicles near the Golgi apparatus, but not in the Golgi saccules. In contrast, at the lateral-basal cell surface the CF particles tended to form clusters. These clusters were more pronounced at higher CF concentrations (0.76 and 1.5 mg/ml) and were associated with elongated cellular processes, which seemed to engulf CF accumulations in a phagocytic manner. Once internalized, CF was found primarily in large irregular structures which appeared to migrate slowly toward the nucleus, reaching a juxtanuclear position after approximately 30 min. CF was observed in lysosomes after 30-45 min and by 90 min most of the CF was confined to large vacuoles and to trimetaphosphatase-positive lysosomes. Similar routes were observed when cells were double-labeled with CF and HRP, where endocytic structures showed co-localization of both tracers. The results of this study indicate the importance of the Golgi region in the intracellular sorting of internalized apical membrane. Furthermore, this work confirms the presence of distinct endocytic pathways at the apical and lateral-basal cell surfaces.

Animals↗

PubMed1986

Further characterization of spontaneous arthritic changes in murine squamo-mandibular joint: histopathological aspects.

The appearance of age-related ulcerative changes in the mouse mandibular condyle were evaluated by light and electron microscopy examinations. Fibrillations appeared along the articular surface and in deeper tissue regions, as early as at six months of age. Such changes were characterized by a marked loss of the tissue's cellularity and by a marked reduction in matrix metachromasia and safranin-0 staining. These microscopical changes were accompanied by a reduced reactivity for both ruthenium red and colloidal iron binding, as noted ultrastructurally. At the same time, increasing numbers of erythrocytes appeared to be adhered to the surface irregularities and were also found in deeper regions within the articular lesions. Using morphological criteria, it became apparent that the degenerative changes of aging articular cartilage started at the more superficial regions of the tissue and only thereafter proceeded toward the chondro-osseous junction. Also, with the advancement of age, the degenerative changes became more severe.

Aging↗

PubMed1986

Morphology and in vivo growth characteristics of an atypical murine proliferative osseous lesion induced in vitro.

Mandibular condyles of late embryonic NMRI mice were used to study the effect of the FBR murine osteosarcoma virus in an in vitro tissue culture system. Chondroprogenitor cells and chondroblastic cells present in the condylar tissue normally undergo rapid differentiation in vitro which results in an advanced stage of bone formation. The infection of condyles with FBR murine osteosarcoma virus induced the transformation of bone progenitor cells and the formation of an atypical proliferative osseous lesion. In markedly disorganized tissue many spindle-like cells, giant cells, and pleomorphic cells were seen together with the formation of large bone spicules and the heavy mineralization of osteoid-like material and of the remaining cartilage. Fibroblast-like cells were found to penetrate from the perichondrial zone into the condylar mass and also into the underlying collagen sponge. The in vivo growth characteristics of FBR murine osteosarcoma virus-infected condyles after 3 days in culture were studied via s.c. transplantation into syngeneic mice. Control condyles developed normal trabecular bone, whereas the infected condyles induced a strong cellular response with the presence of atypical cells and newly formed connective tissue and bone in situ. These observations raise the possibility of a novel approach for further investigations related to numerous aspects of virus-induced osteosarcomagenesis.

Animals↗

PubMed1985

Morphologic and cytochemical changes in maturing and osteoarthritic articular cartilage in the temporomandibular joint of mice.

We studied the light microscopic, ultrastructural, and cytochemical characteristics of the temporomandibular joints of male ICR mice, from early neonatal life until they reached senescence, when spontaneous osteoarthritis is a common phenomenon. Aging of mandibular condylar cartilage was accompanied by decreasing total proteoglycan content and by an unmasking of collagen fibers, with no shift in collagen type. Fibronectin was also commonly present on the articular surface of specimens from old animals. Chondrocytes of aged mice contained an increased number of lysosomes, and their adjacent matrix vesicles reacted positively for acid phosphatase and arylsulfatase, but not for alkaline phosphatase. Such vesicles were also found to be devoid of calcium complexes and, thus, did not appear to be involved in the mineralization process. Similar age-related changes have been described in human mandibular condyles; hence, the male ICR mouse could serve as a useful model for studies of spontaneous osteoarthritis in the human mandibular joint.

Acid Phosphatase↗