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PubMed1981

[Unique tissue differentiation in peripheral nervous system tumors (glandular neurofibroma)].

A rare observation of glandular differentiation in neurofibroma of the right orbit is described. Data on another 7 similar tumors reported in the literature are presented. The problems of histogenesis of such neoplasias and difficulties of their diagnosis are discussed. Glandular neurinomas and neurofibromas are characterized by a malignant course and trend for relapses favouring high lethality in this disease.

Adult↗
PubMed1995

Molecular cloning of two rat Na+/Pi cotransporters: evidence for differential tissue expression of transcripts.

Recently, Na+/Pi cotransport activity has been demonstrated in rat liver hepatocytes. Here, we report the isolation of two Na+/Pi cotransporter cDNAs (RNaPi-1a and RNaPi-1b) from a rat liver cDNA library. The two cDNAs have the same coding but different 5'-untranslated regions. The rat cDNAs encode a polypeptide of 465 amino acids, having 62% and 66% identity with the rabbit NaPi-1 and human kidney Na+/Pi cotransporter, respectively. Northern blot analysis showed that a RNaPi-1a--specific probe detected two major transcripts (2.3 and 1.8 kb), whereas a RNaPi-1b--specific probe hybridized with one transcript (1.8 kb) in rat kidney, liver, and hepatocytes in primary culture. Rat liver expressed much higher levels of RNaPi-1a than RNaPi-1b, whereas the converse was true for rat kidney. Low levels of RNaPi-1 mRNAs were also detected in rat heart, brain, and skeletal muscle. These findings indicate that there are at least two isoforms of RNaPi-1 transcripts expressed in liver and kidney and that the levels of expression of the RNaPi-1a and RNaPi-1b may be controlled by tissue-specific factors.

Amino Acid Sequence↗
PubMedDate not supplied

[Differentiation of corneal tissues (role of the nerve factor)].

The results of various experimental exposures of corneal tissue are presented. Morphological studies demonstrate a decrease of tissue differentiation and its accelerated growth and impairment of tissue relationships depending on injury to its nervous system. The author considers that the degree of tissue differentiation, tissue correlations, and functional intactness of tissue depend on the status of the nervous system.

Animals↗
PubMed2000

Intracorporeal imaging and differentiation of living tissue with an ultra-high-frequency ultrasound probe.

Intraoperative diagnostic tissue differentiation is expected to be useful clinically. We have fabricated a 3-mm diameter rod-shaped ultrasound (US) probe mounted with a 120-MHz transducer whose lateral resolution is the same as the cellular size of 13 microm. The probe can image a microscopic structure (i.e., the cellular arrangement inside intracorporeal living tissue). We imaged normal kidney tissue of a living mouse and tumor tissue implanted in another mouse kidney. We anesthetized the mice, exteriorized the kidneys, and punctured the kidneys with the probe. Renal corpuscle-like structures were seen in the healthy kidney, but a wavy spindle-like structure was seen in the tumor. The similarity between the ultrasonic images and histological sections taken from the imaged organs demonstrates the possibility of real-time tissue differentiation by ultra-high-frequency US.

Animals↗
PubMed1993

Differentiation and growth of rat egg-cylinders cultured in vitro in a serum-free and protein-free medium.

Modified organ cultures of rat egg-cylinders were grown for 2 weeks in Eagle's minimal essential medium (MEM) without serum. Differentiation of epidermis and cartilage in the cultures deprived of serum was comparable to that in fully serum-supplemented medium, whereas other differentiated tissues were rare or absent. The purpose of the experiment was to determine whether terminal tissue differentiation is modified by various added factors. The factors used affected the growth and/or differentiation of explants as follows: bovine serum albumin and human transferrin had a positive permissive influence on the appearance of neuroblasts; human transferrin alone stimulated the formation of lentoids, a relatively rare tissue. Retinoic acid inhibited cartilage formation and stimulated the differentiation of cylindrical epithelium; neural growth factor inhibited the growth of explants; and 5-azacytidine impeded the survival of explants. One can conclude that these factors influenced the growth and differentiation of the early rat embryos cultured in a chemically defined medium.

Animals↗
PubMed1989

Oncogene expression in cholangiocarcinoma and in normal hepatic development.

The expression of the proteins encoded by the ras, myc, and erb B-2 oncogenes was examined in 63 paraffin-embedded human cholangiocarcinomas of Thai and English origin using immunohistochemistry. The observed distributions were compared with oncogene expression in a series of human hepatocellular carcinomas. In an attempt to relate expression of these three oncogenes to specific stages of normal tissue differentiation, tissue sections of normal fetal, infant, and adult human livers were also examined. Of 63 cholangiocarcinomas, 59 (95%) expressed p62 c-myc, 47 (75%) expressed p21 c-ras, and 46 (73%) expressed p190 c-erbB-2. The expression of c-myc and c-ras but not of c-erb B-2 correlated directly with tumor differentiation as judged by morphologic criteria. No difference was observed in oncogene expression between intrahepatic and extrahepatic cholangiocarcinomas. Twelve of 14 hepatocellular carcinomas (86%) stained positively for all three oncoproteins. During normal liver development, expression of c-myc and c-ras was shown to occur from 18 weeks' gestation until 5 years of age, but not thereafter. Expression of c-myc, c-ras, and c-erbB-2 oncogenes may be used as immunohistochemical markers to distinguish cholangiocarcinoma from nonneoplastic biliary tissues, and may provide useful information concerning the cell biology of tumor differentiation.

Adenoma, Bile Duct↗
PubMed1997

Developmental expression of perlecan during murine embryogenesis.

Perlecan is a modular heparan sulfate proteoglycan that is an intrinsic constituent of all basement membranes and extracellular matrices. Because of its strategic position and unique structure, perlecan has been implicated in modulating the activity of various growth factors required for normal development and tissue homeostasis. To gain insights into the potential function of perlecan in vivo, we examined the spatiotemporal distribution of its mRNA and protein core during murine embryogenesis. We utilized a new affinity-purified antibody that recognizes specifically the protein core of perlecan together with an in situ RT-PCR approach to perform a systematic analysis of perlecan expression and deposition during murine ontogeny. Perlecan appeared early (E10.5) in tissues of vasculogenesis including heart, pericardium, and major blood vessels. Its early expression coincided with the development of the cardiovascular system. Subsequently (E11-13), the greatest deposition of perlecan occurred within the developing cartilage, especially the cartilage undergoing endochondral ossification, where it remained elevated throughout all the developmental stages, and up to adulthood. Interestingly, the mRNA levels of perlecan were always higher in all the vascularized tissues, principally within endothelial cells, while chondrocytes displayed relatively low mRNA levels. This suggests a higher biosynthesis and turnover rates in the blood vessels vis-à-vis those of cartilaginous and other mesenchymal tissues. During later stages of development (E13-17.5) perlecan mRNA levels progressively increased and its expression correlated with the onset of tissue differentiation of various parenchymal organs including the developing kidneys, lungs, liver, spleen, and gastrointestinal tract. The central nervous system showed no perlecan expression with the exception of the calvaria and choroid plexus. Collectively, the results indicate that perlecan may play crucial roles not only in vasculogenesis but also in the maturation and maintenance of differentiated tissues, including cartilage.

Animals↗
PubMed1998

Tissue engineering: generation of differentiated artificial tissues for biomedical applications.

A new field in biomedical science has been established. Cell biologists, engineers, and surgeons now work within a team. Artificial connective, epithelial, or neuronal tissues are being constructed using living cells and different kinds of biomaterials. Numerous companies and laboratories are presenting dynamic developments in this field. Prognoses predict that, at the beginning of the coming century, the industry of tissue engineering will reach the importance of the present genetic technology. An enormous demand for organ and tissue transplants motivates research activities and drives the acquisition of innovative techniques and creative solutions. At the front of this development is the creation of artificial skin for severely burned patients and the generation of artificial cartilage for implantation in articular joint diseases. Future challenges are the construction of liver organoids and the development of an artificial kidney on the basis of cultured cells. In this paper we show strategies, needs, tools, and equipment for tissue engineering. The presupposition for all projects is the induction, development, and maintenance of differentiation within the tissue under in vitro conditions. As experiments in conventional culture dishes continued to fail, new cell and tissue culture methods had to be developed. Tissues are cultured under conditions as close as possible to their natural environment. To optimize adherence or embedding, cells are grown on novel tissue carriers and on individually selected biomatrices or scaffolds. The tissues are subsequently transferred into different types of containers for permanent perfusion with fresh culture medium. This guarantees constant nutrition of the developing tissue and prevents the accumulation of harmful metabolites. An organo-typical environment for epithelial cells, for example, is obtained in gradient containers, which are permanently superfused at the apical and basal sides with different media. Long term experiments result in cultured tissues in a quality thus far unreached.

Biomedical Engineering↗
PubMed2006

Wavelet-based feature extraction applied to small-angle x-ray scattering patterns from breast tissue: a tool for differentiating between tissue types.

This paper reports on the application of wavelet decomposition to small-angle x-ray scattering (SAXS) patterns from human breast tissue produced by a synchrotron source. The pixel intensities of SAXS patterns of normal, benign and malignant tissue types were transformed into wavelet coefficients. Statistical analysis found significant differences between the wavelet coefficients describing the patterns produced by different tissue types. These differences were then correlated with position in the image and have been linked to the supra-molecular structural changes that occur in breast tissue in the presence of disease. Specifically, results indicate that there are significant differences between healthy and diseased tissues in the wavelet coefficients that describe the peaks produced by the axial d-spacing of collagen. These differences suggest that a useful classification tool could be based upon the spectral information within the axial peaks.

Algorithms↗
PubMed1984

Lamellar bodies in differentiating insect tissues during basal lamina formation as revealed by tannic acid.

Tannic acid penetrates differentiating tissues differentially resulting in variable contrast, extraction and dense bodies with a lamellar substructure. The penetrability appears to correlate with the existence and/or robustness of a basal lamina. In the male genital tract, probably of mesodermal origin, tannic acid penetrates the epithelium until there is a basal lamina, but in the ectodermal bursa copulatrix it does not penetrate since there is always a basal lamina. The lamellae of the dense bodies have a center-to-center spacing of 4.65 +/- 0.025 nm, dimensions which resemble those of phospholipids.

Animals↗
PubMed2001

Differentiation of rat neural tissue in a serum-free embryo culture model followed by in vivo transplantation.

AIM: To analyze neural tissue differentiation in a unique, chemically-defined in vitro culture model of gastrulating rat embryo proper by use of transmission electron microscopy (TEM), proliferating cell nuclear antigen (PCNA) expression, and in vivo transplantation after a 2-week culture in serum-free or serum-supplemented media. Influence of protein-free medium unfavorable for differentiation of neural tissue in vitro was compared with favorable serum-free media enriched with transferrin or albumin. Differentiation of mesodermal derivatives in transplants was also investigated. METHODS: We cultivated 9.5-day-old Fischer rat embryos on the gas-liquid interface in the protein-free Eagle's Minimum Essential Medium (MEM), in MEM with either iron-saturated holotransferrin (50 microg/mL) or iron-free apotransferrin (50 microg/mL), and in medium saturated with either bovine serum albumin (BSA) (4 mg/mL or 400 microg/mL) or rat serum (50%). After the two-week culture period, light microscopy, TEM, and immunohistochemical method for detection of PCNA were done. Some explants were transplanted under the kidney capsule of adult male rats to be cultured in vivo for additional two weeks. Chi-square test or Fisher exact test were used to compare the proportion of tissues developed. RESULTS: Proportion of differentiated neural tissue was similar in explants cultivated in apotransferrin- and holotransferrin-supplemented media (13/33 and 9/20, respectively), but higher than in explants cultivated in protein-free medium (1/13). Neurons and glia cells produced a neuropil structure. Myelinization occurred only in serum-supplemented medium. PCNA expression was detected in a small number of neural tissue cells, even in serum-free cultivated embryos. Differentiation of brain-like tissue, cerebrospinal, and vegetative ganglionic cells occurred in all groups of transplants. However, in the transplants derived from protein-free medium, the proportion of neural tissue, cartilage, bone, skeletal and smooth muscle was significantly lower than in transferrin-supplemented media (p<0.01). Albumin seemed to promote differentiation of all tissues except vegetative ganglionic cells. CONCLUSION: Nerve tissue differentiated to a rather high degree in a two-week in vitro postimplantation embryo culture. Transferrin or albumin, as the only proteins used for serum-free precultivation, significantly improved subsequent differentiation of nerve tissue and mesodermal derivatives in transplants in vivo.

Animals↗
PubMed1983

Immunohistochemical demonstration of altered functional differentiation of pancreatic tissue in sacrococcygeal teratomas.

The finding of teratomas with mature-appearing pancreatic tissue showing abnormal production of immunoreactive amylase appears to contradict earlier suggestions that somatic tissue in teratomas that appears mature also functions normally. It therefore seems judicious to study carefully both morphologic and functional characteristics of tissues in teratomas before utilizing them as experimental models of tissue differentiation, since at least in the case of human amylase, functional differentiation does not always follow morphologic differentiation.

Amylases↗
PubMed1997

Tissue factor expression during monocyte-macrophage differentiation.

Tissue factor (TF), the high affinity receptor and cofactor of factor VII, is considered as the main procoagulant in stimulated monocytes and macrophages. We studied the effect of longterm culture (differentiation) on "spontaneous" and induced (LPS) expression of TF (mRNA, antigen, cell surface associated VIIa-cofactor activity) in isolated human monocytes. TF was expressed transiently in monocytes cultured on Teflon membranes (suspension monocytes, Mo-S) and on plastic dishes (adherent monocytes, Mo-A), reaching maximal levels between days 3 and 5. Increased expression of TF was accompanied by increased stable expression of macrophage specific markers (CD71, the mannose receptor, the scavenger receptor). Bacterial lipopolysaccharide (LPS) induced (additional) TF mRNA, antigen, and activity in both Mo-S and Mo-A. In Mo-S and Mo-A of days 3 to 5, the period in which there was "spontaneous" expression of TF, TF response to LPS was considerably lower. It is concluded that during monocyte-macrophage transition, TF is "spontaneously" and transiently expressed and that with respect to TF induction the responsiveness of the cells to LPS is maintained.

Cell Differentiation↗
PubMed2001

Activation of lymphocytes inhibits human monocyte to macrophage differentiation.

Tissue macrophages (MAC) differentiate from circulating blood monocytes (MO) during a maturation step that is of crucial importance for their functional competence. In vitro a similar process of maturation can be observed, if MO are cultured in the presence of serum. In the work presented here, we show that activated lymphocytes can interfere with MAC differentiation. Resting lymphocytes have only marginal influence upon MO to MAC transition in vitro. However, if cells are activated by the lectins PWM or ConA or by double-stranded RNA (polyinosinic-polycytidylic acid, pI:C), normal MAC maturation is suppressed: MO stay small and do not acquire MAC maturation-associated surface molecules like carboxypeptidase M (CPM, determined by antibody MAX.1) or CD84 (determined by antibody MAX.3). This phenomenon can be induced by small numbers of lymphocytes and can be transmitted by soluble factors in cultures stimulated with ConA or PWM. IFN-gamma is present in these conditioned media and partially suppresses MAC maturation but cannot fully substitute for the conditioned media. On the contrary, in pI:C stimulated cultures, suppression of MAC differentiation is dependent on cell-cell contact. In conclusion, activated lymphocytes are able to suppress the terminal differentiation of MAC by several pathways depending on the mode of lymphocyte stimulation.

Antigens, CD↗