Biomedical subjects

G Tajana

Publications and source records attributed to G Tajana.

At least 19 recordsLinked to original sources

PubMed1994

Mandibular lengthening by external distraction: an experimental study in the rabbit.

OBJECTIVE: To observe the development of bone at different times during the period of mandibular lengthening by external distraction using Ilizarov's transosseous osteosynthesis technique. MATERIALS AND METHODS: Fifteen rabbits, 2 to 3 kg in weight, were used for this experiment. The left side of the mandible was exposed and a corticotomy was performed with a water-cooled drill. After 12 hours, distraction was started and continued 1 mm per day for 2 weeks. Plain radiography and three-phase bone scan scintigraphy were performed on the 1st, 7th, and 14th postoperative days. The mandibles were then either removed for immediate histologic evaluation or after 2, 5, or 8 weeks of postdistraction fixation. RESULTS: Elongation of up to 11 mm was achieved. Radiographic and scintigraphic evaluation suggested a residual inflammation on the 7th day and definite ossification on the 14th day. Histologic observations of the distraction site showed a gradual change from an amorphous matrix to a fibrous matrix and, finally, an osseous-like tissue. CONCLUSION: Bone lengthening by gradual distraction is commonly used in tubular bones. To achieve mandibular lengthening it is necessary to resolve many problems. Morphologic, radiographic, scintigraphic, and histologic observations confirm that mandibular lengthening by external distraction is possible, with the formation of new bone tissue.

Animals↗

PubMed1991

Macrophage activation induced by different carbon fiber-epoxy resin composites.

The activation of cells by interaction with solid surfaces is important in many settings, including the response of tissue to implanted materials. However, few comprehensive studies of both cell migration and activation have been performed so that the connection between these events and immunological activation against foreign material is not well understood. In the present study, synthesis and expression of Ia antigens by peritoneal exudate macrophages after implantation of different carbon fiber composites in the rat peritoneal cavity have been investigated in order to determine whether the type of material implanted affected the composition of Ia-bearing cells of the exudate. The results have confirmed the low level of expression of Ia on resident peritoneal macrophages; while we have found that macrophages, harvested after implantation, express a different amount of Ia related to the different cure cycles of the composite material used.

Animals↗

PubMed1991

Rat peritoneal immune response to carbon fibre reinforced epoxy composite implants.

The aim of this paper was to evaluate the histocompatibility of differently cured carbon fibre reinforced epoxy composites, studying their potential to induce an intolerance reaction in neighbouring tissues after peritoneal implantation in the rat. According to the microscopic and scanning electron microscope findings, the inductive capacity to generate connective tissue and cellular reaction was greatest in the partially cured material compared to the fully cured material. In addition, only the partially cured material implants appeared totally coated by macrophages at various stages of activation. The differences in the cellular reactions and scar tissue deposition in the interstices of these two composites are probably related to the chemical surface properties rather than to the structural characteristics of the materials.

Adsorption↗

PubMed1988

A retrovirus carrying the polyomavirus middle T gene induces acute thrombocythemic myeloproliferative disease in mice.

Mice inoculated with an artificially constructed retrovirus carrying the middle T gene of polyomavirus develop acute myeloproliferative disease with severe thrombotic and hemorrhagic disorder and impaired platelet function. The megakaryocytic lineage appears to be a target for polyoma-murine leukemia virus infection and middle T gene expression. This newly described disease represents a unique model system for studying disorders of the megakaryocytic lineage.

Adenosine Triphosphate↗

PubMed1985

[End-to-side anastomosis made with a short circulatory interruption in the receiving vessel. Experimental model in the rat].

End to side microsurgical anastomoses between vessels of small calibre require interruption of blood flow of about 25-40 min. In terminal vascular beds this time may be incompatible with the cellular survival. The authors refer their experience in rats with a partly original experimental technique requiring less time of clamping the receiving vessel (about 3-4 min), as the main part of the anastomosis is performed between the wall of the donor vessel and the adventitia of the receiving vessel, without interruption of blood flow in this latter. Histological examinations, performed 21 days later, reveal a patency rate of 60%.

Angiography↗

PubMed1984

Transglutaminase-mediated modifications of the rat sperm surface in vitro.

Two transglutaminase-mediated modifications of the rat epididymal spermatozoon surface were demonstrated in vitro. Transglutaminase was effective in promoting the binding of spermidine to the sperm. Moreover, the enzyme, by reacting with one of the major proteins secreted by the rat seminal vesicle epithelium, produced a modified form of the protein with a higher molecular weight and the capability of binding to the sperm cells. A specific physiological role for the enzyme, bringing about modifications of the rat sperm surface in the seminal fluid environment, is suggested.

Acyltransferases↗

PubMed1984

[Ultrastructure of human cerebral neoplasms in vitro: glioma].

The authors describe the in vitro structural features of cellular populations derived from human gliomas. They report the structure of each population, and hypothesize on the correlation among these different cell populations. The findings of this study show some of the individual glioma cell lines to have characteristic structures.

Brain Neoplasms↗

PubMed1984

[Ultrastructure of human cerebral neoplasms in vitro: medulloblastoma].

The fine structure of five lines of medulloblastoma cells in long-term cell cultures are described. The cell cultures were fixed in situ by the rapid exchange of the medium for the fixative solution consisting of 3% glutaraldhyde in 0.1 M Na cacodylate-HC1 buffer with 0.1 M sucrose (pH 7,2, total osmolality 510 mOsm, vehicle osmolality 300 mOsm). The cultures were subsequently postfixed in 1% OsO4 in water at room temperature and dehydrated in a graded series of ethanol solutions. In the second change of 100% ethanol they were stained with 2% uranyl acetate for 10 minutes. They described the structural characteristics of these cells in relation to the various phases of the culture, is similar to the well known of in vitro cellular embryonal systems (spongioblasts).

Adolescent↗

PubMed1984

Location of 64K collagen producer chondrocytes in developing chicken embryo tibiae.

The synthesis of a new low-molecular-weight collagen by cultured chicken embryo chondrocytes has been recently demonstrated (Capasso et al., Exp. Cell Res. 142:197-206, 1982; Gibson et al., J. Cell Biol. 93:767-774, 1982; Schmid and Conrad, J. Biol. Chem. 257:12444-12450, 1982). In this paper we report results on the location of chondrocytes synthesizing this new collagen (64K collagen) in the developing chicken embryo. The 64K collagen is synthesized in very large amounts by cells concentrated at the diaphysis of 9-day-old and at the epiphysis of 17-day-old embryo tibiae. These regions are characterized by a remodeling of the cartilage matrix leading to the replacement of the cartilage with bone tissue; therefore, this collagen appears to be a marker of a specific developmental stage of chondrocytes. The origin of cells competent for the synthesis of the 64K collagen is also discussed.

Animals↗

PubMed1982

The culture of chick embryo chondrocytes and the control of their differentiated functions in vitro. I. Characterization of the chondrocyte-specific phenotypes.

We have maintained chick embryo chondrocytes in culture for more than 2 months, passaging the floating cells in the absence of ascorbic acid. Throughout the culture period some of the cells attached to the dish, assuming an epithelial-like morphology and subsequently giving rise to new floating cells. The interconversion of the two cell populations was highest in primaries and decreased with the aging of the culture. Cartilage cells synthesized pro-alpha 1 (II) collagen and sulphated proteoglycans in vitro; compared with floaters, the epithelial-like cells secreted relatively large amounts of fibronectin. When ascorbic acid was added to the medium, all cells attached, maintaining their rounded shape; in this condition the pro-alpha, (II) collagen was matured and collagen fibres were detectable outside the cells. Other specific proteins synthesized by the chondrocytes in culture were also identified. One of these, a 64 K collagenase-sensitive protein, was not related to the type II collagen and may represent a new collagen type.

Animals↗

PubMed1982

Intermediate filaments in a human medulloblastoma cell strain.

The fine structure of a human medulloblastoma cell strain characterized by the emission of two types of cytoplasmic processes was studied with particular regard to the cytoskeleton organization of the cell processes. A particular abundance of intermediate filaments (6-11 nm) was found in the primary processes. This study suggests that this abundance can strongly condition the cell shape of in vitro medulloblastoma cells and can represent a marker of this type of cells.

Cell Line↗

PubMed1982

Block in the expression of differentiation markers of rat thyroid epithelial cells by transformation with Kirsten murine sarcoma virus.

Well-differentiated epithelial cells, derived from primary cultures of normal rat thyroid glands (T-79 cells), as well as a cloned cell line also derived from normal rat thyroid glands (FRT-L cells) were infected with Kirsten murine sarcoma virus carrying outer coat of the helper Kirsten murine leukemia virus. Infected T-79 and FRT-L cells changed morphologically and began to proliferate rapidly, suggesting malignant transformation by the virus. Both cell lines can support the replication of both transformation-competent and transformation-incompetent viruses such as murine or rat leukemia viruses. Infected T-79 and FRT-L cells had a high colony-forming efficiency (68 and 64%, respectively) when grown in agar and formed tumors when transplanted s.c. into syngeneic rats. These tumors morphologically resemble undifferentiated adenocarcinomas, thus showing that Kirsten sarcoma virus carrying the outer coat of the helper Kirsten murine leukemia virus is able to transform differentiated epithelial cells. Transformed T-79 and FRT-L cells, in contrast to uninfected cells, neither secrete thyroglobulin concentrate iodide, two biochemical markers of differentiated thyroid function. Thus, expression of the differentiated phenotype is blocked as a consequence of cell transformation. The system described may be useful in studying epithelial cell carcinogenesis in terms of regulated expression of differentiated functions.

Animals↗

PubMed1980

[Nomarski interference microscopy: use of combined contrast uranyl acetate-PTA for in vitro observation of monolayer cultures].

In this paper is reported a technique for the fixation and staining of cellular monolayers in vitro for observation by the interferential microscope according to Nomarski. This method includes the use of glutaraldehyde at 2.5% in phosphate buffer 0.1 M pH 7.5 and the sequential use of Uranil acetate (0.9% in absolute alcohol) and phosphtungstic acid (1% in absolute alcohol). This study has been conducted on 3 cellular lines: PC12 (rat pheocromocytoma), R.P.C. (rat pineal cells), primary culture obtained from a human carcinoma of the uterus.

Acetates↗

PubMed1980

[Practical staining method: T-OPA triple stain].

The following procedure has proven to be successful as routine trichrome stain on paraffin embedded material: 1) Mayer's hemalum for 10 min, followed by running tap water wash; 2) staining in 1% Orange G in 1% acqueous PTA for 5 min and rinsing a few seconds in distilled water; 3) Aniline blue 1% acqueous for 5 min, followed by few seconds distilled water wash. Dehidratation in ethanol, or by blotting followed by t-buthanol or 1:3 terpineol-xylene, clearing and mounting, completed the procedure.

Acridine Orange↗

PubMed1980