Histology and histopathology Vol.13, nº 2 (1998)
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- PublicationOpen AccessThe lymphocyte-dendritic cell system(Murcia : F. Hernández, 1998) Imai, Yutaka; Yamakawa, Mitsunori; Kasajima, TakeshiAntigens provoke immune responses. The group of immunocompetent cells related directly to this response includes T and B cells, macrophages (MO) and dendritic cells (DCs). DCs acting as antigen-presenting cells have been recently recognized to be important in initiating the immune response. B cells and follicular dendritic cells (FDCs), the major immunocompetent cells in the B-cell dependent area, play an important role in humoral immunity, while T cells and interdigitating cells (IDCs), which are the major immunocompetent cells in the T-cell dependent (TD)-area, play an important role in cellular immunity. The B cell-IDC interaction in the TD-area is also essential for the B-cell response against TD-antigen. Consequently, the lymphocyte-DC interaction is essential in the response to antigenic stimulation and in inducing the potent effector cells. B cell-DC, T cell-DC and DC-B cell-T cell interactions are regulated in predetermined sites by complex and varied mechanisms. Much recent evidence demonstrates that DCs modulate lymphocyte biology in its broadest aspects, including generation, differen-tiation, proliferation, and activation. In this review, we outline recent studies on the generation, structure, and function of lymphatic tissues, propose the concept of the "Lymphocyte-Dendritic Cell System (LDS)", and finally describe the significance and functions of this system in health and disease.
- PublicationOpen AccessPlatelet-Derived Growth Factor PDGF in primary brain tumours of neuroglial origin(Murcia : F. Hernández, 1998) Smits, A.; Funa, K.It has become clear that disruptions in the genome of somatic cells play a causative role in tumour development. We know that the ultimate formation of a malignancy is the result of a multistep process in which the functional loss andlor the altered or increased expression of genes play important roles. One such family of genes are the oncogenes, encoding protein products with mainly growth stimulating effects. Platelet-derived growth factor (PDGF) belongs to the family of oncogenes. It is likely that PDGF plays an essential role in the development of at least a subgroup of malignant astrocytic tumours that do not contain amplification of the EGF-receptor. The expression of PDGF a-receptors is related to tumour progression in these tumours, and some of the most malignant tumours were shown to contain amplification of the PDGF areceptor. It is also clear now from several experimental studies that PDGF can drive the transformed phenotype, and that PDGF antagonists, by blocking the PDGF autocrine pathway revert the transformed phenotype of certain tumour cells. Because of the findings that receptor protein tyrosine kinases such as the EGF- and the PDGF-receptor play a crucial role in the development of gliomas, it is possible that inhibitors of the phosphorylation of the protein tyrosine kinases will be future candidates for glioma therapy. They might be able to at least delay the development of a fully malignant glioma. The role of PDGF in other tumours of neuroglial origin in the central nervous system has not been studied as extensively as its role in gliomas. Recent data suggest that also for the primitive neuroectodermal tumours overexpression of the PDGF a-receptor is related to malignancy of the tumours. For other tumours, such as neuroblastomas, PDGF exerts a differentiating rather than a mitogenic function and is an important survival factor. Further studies are needed to elucidate the role of PDGF in these non-glial primary brain tumours. Moreover, for a complete understanding of the role of PDGF in malignancies of the CNS, it is important to explore its function in the development of the normal Offprint requests to: Dr. Anja Smits, Department of Neurology, University Hospital Uppsala, S-751 85 Uppsala, Sweden CNS further.
- PublicationOpen AccessLow-intensity ultrasound energy applied to the testes of aged rats(Murcia : F. Hernández, 1998) Haddad, S.; Franci, J.A.A.; Petenusci, S.O.; Lamano Carvalho, T.L.Previous studies from our laboratory have shown that low-intensity ultrasound applied to the scrotum of prepubertal rats causes a 62% increase in plasma testosterone, suggesting a possible stimulation of LH receptors andtor the enzymes controlling the steroidogenic process. The purpose of the present study was to investigate whether low-intensity ultrasound has a stimulatory effect on the androgenic activity of aged testes. In addition to plasma testosterone, LH and FSH, the testicular spermatogenic status was also analysed. Ultrasound applied to the scrotum of aged rats did not stimulate sperm production, which was significantly reduced compared to sexually mature animals, and failed to re-establish the steroidogenic testicular function, which was decreased by 74%, suggesting an inherent loss of gonadal steroidogenic competence.
- PublicationOpen AccessGut glycoconjugates in Sparus aurata L. Pisces, Teleostei. A comparative histochemical study in larval and adult ages(Murcia : F. Hernández, 1998) Domeneghini, C.; Pannelli Straini, R.; Veggetti, A.This study examined the gut of the euryaline fish Sparus aurata, from the pharynx to the rectum. The specimens were collected from adult animals, both sexes, and several larval and juvenile stages, from 4 to 135 days of age. Histochemical methods to distinguish neutral and acidic glycoconjugates, as well as specific techniques to identify acidic glycoconjugates which contained 0-acylated sialic acids were used. The presence and distribution of sugar residues in the oligosaccharide side chain of glycoconjugates were investigated with the use of biotinylated lectins. The pharynx and oesophagus of adult fishes showed the presence of abundant secretory cells which synthesized a large quantity of neutral, as well as sulphated and sialylated glycoconjugates, with different cellular combinations of them in the proximal and distal tract. This may be related to the complex functions carried out by this end of the gut in a marine euryaline fish. Epithelia1 secretory cells were found in the developing oesophagus during larval life (14 days) earlier than in the stomach and intestine (34 days). The simple columnar epithelium that lined the gastric mucosa of adult fish synthesized a mixture of neutral and acidic glycoconjugates, whereas during larval life it was shown to contain neutral glycoconjugates only. The intestinal goblet cells were shown to secrete both neutral and acidic glycoconjugates, especially sulphated forms. The adherent mucus gel of the gastric and intestinal mucosa contained many sugar residues, as revealed by lectin histochemistry. This work clearly demonstrates that the quality of gut mucosubstances varies in different ages and in regions of the fish alimentary canal. This is possibly caused by changes in environmental conditions and may in turn sustain functional alterations of the digestive apparatus.
- PublicationOpen AccessThe induction of gut hyperplasia by phytohaemagglutinin in the diet and limitation of tumour growth(Murcia : F. Hernández, 1998) Pryme, I.F.; Pusztai, A.; Bardocz, S.; Ewen, S.W.B.The growth of a transplantable murine non- Hodgkin lymphoma tumour, developing either intraperitoneally as an ascites tumour or subcutaneously as a solid tumour, has been shown to be markedly diminished by including phytohaemagglutinin (PHA), a lectin present in raw kidney bean (I'haseolus vulgaris) in the diet. In NMRl mice fed PHA within the range 0.45-7.0 mg/g diet, tumours which developed during a 10 day period after subcutaneous injection of cells were about 35% of the dry weight of those in lactalbumin-fed (control) animals. The reduced rate of growth occurred in a dose-dependent manner within the range 0.45-3.5 mg/g diet. Based on these observations it has been suggested that a competition between the gut epithelium undergoing hyperplasia and the developing tumour may occur for nutrients from a common body pool, and this may be an important factor with regard to the observed initial low level of tumour growth following the feeding of a PHA-containing diet. Observations which showed that the level of hyperplasia of the small bowel in response to feeding the PHA diets was higher in noninjected mice compared to those which had been injected with tumour cells substantiated the concept of competition between gut and tumour for nutrients etc. required for growth. Experiments with a second murine tumour cell line (a plasmacytoma) in Balblc mice gave similar results indicating that the effect of PHA was not restricted to a single tumour system.