Histology and histopathology Vol.15, nº 2 (2000)

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Open Access
Mineralization of human premolar occlusal fissures. A quantitative histochemical microanalysis
(Murcia : F. Hernández, 2000) Campos, Antonio; Rodriguez, I.A.; Sanchez-Quevedo, M.C.; García, J.M.; Nieto-Albano, O.H.; Gómez de Ferraris, M.E.
The mechanisms of cariogenesis in occlusal fissures remain elusive because of limited information about fissure structure and wall mineralization. The purpose of the present study was to determine the correlation between morphological patterns in occlusal fissures in human premolars and quantitative histochemical patterns of mineralization in the walls of these formations. We used scanning electron microscopy and quantitative X-ray microanalysis with the peak-tolocal background ratio method and microcrystalline calcium salts as standards. We distinguished three morphological patterns of fissures in scanning electron microscopic images. The wall of the fissures was less mineralized than the control enamel in all three types of fissures. Because the fissure walls are hypomineralized, we suggest that practicing dentists should take into account the degree of mineralization when they are preparing the fissures for the application of sealant.
Open Access
Comparative study of tumor angiogenesis and immunohistochemistry for p53, c-ErbB2, c-myc and EGFr as prognostic factors in gastric cancer
(Murcia : F. Hernández, 2000) Sanz Ortega, J.; Steinberg, S.M.; Moro, E.; Saez, M.; Lopez, J.A.; Sierra, E.; Sanz Esponera, J.; Merino, M.J.
Gastric cancer (GC) continues to be a highly aggressive malignancy with poor prognosis and low survival rates. The survival of patients with GC depends mainly on the stage of the disease, with early GC having a 5 year survival of 90-100% and advanced tumors a 5 year survival of 15-25%. The role of other prognostic factors in these tumors is still under investigation. 28 gastric dysplasia, 45 Early GC and 98 Advanced Gastric Cancers were evaluated for expression of the oncogenes p53, c-ErbB2, c-myc and the EGFr in paraffin-embedded material utilizing Avidin-Biotin immunohistochemistry techniques. In 34 cases of GC microvessel density (MVD) was determined in CD34 stained sections. Statistical correlations with stage, histologic type, differentiation degree, location, size, ploidy patterns and overall survival were done. The Mantel-Cox test was performed to evaluate which factors had an independent prognostic value. Both, tumor angiogenesis and p53 protein expression were statistically associated (95% confidence intervals) with overall survival in patients with GC. p53 protein expression was also correlated with cardial location, nodal involvement and tumor stage. c-ErbB2 may recognize a group of highly aggressive well differentiated adenocarcinomas with worse prognosis. c-myc was also significantly enhanced in well differentiated tumors. EGFr showed no significant associations. Mantel-Cox was performed to compare the prognostic value of tumor stage, p53 protein expression and tumor angiogenesis. Tumor angiogenesis was the most important prognostic indicator to predict overall survival in our series. p53 expression was not independent and did not provide additional prognostic information to tumor stage. Our study suggests that angiogenesis as demonstrated by microvessel counts in CD34 stained sections is a significantly important Offprint requests to: Julian Sanz Ortega, MD, Departamento de Anatomia Patolbgica, Hospital Universitario "San Carlos". Martin Lagos s.n., Madrid 28040, Spain. Fax: 34-913303032, e-mail: jsanz@ hcsc.insalud.es prognostic factor for predicting survival in gastric cancer.
Open Access
Effects of ethanol on the ultrastructure of the hamster thyroid C-cell
(Murcia : F. Hernández, 2000) chen, H.; Hayakawa, D.; Emura, S.; Tamada, A.; Ozawa, Y.; Taguchi, H.; Yano, R.; Shoumura, S.
The morphology of the thyroid C-cells in golden hamsters after short- and long-term treatment with ethanol was studied. Immunohistochemistry was applied to examine the distribution of the C-cells in the thyroid gland. In the short-term experimental animals, the Golgi complexes and the granular endoplasmic reticulum were well developed and the number of the secretory granules was decreased as compared with those of the control animals. These findings suggest that the cellular activity of the thyroid C-cell is stimulated after short-term treatment with ethanol. The morphology of the thyroid C-cells of the long-term experimental animals was similar to that of the controls. It is conceivable that long-term treatment with ethanol does not affect the function of the C-cell.
Open Access
Melatonin, experimental basis for a possible application in breast cancer prevention and treatment
(Murcia : F. Hernández, 2000) Cos, S.; Sánchez Barceló, E. J.
The role of the pineal as an oncostatic gland has been studied in animal models of tumorigenesis, especially on those concerning the mammary gland. The general conclusion is that experimental manipulations activating pineal gland, or the administration of melatonin, reduce the incidence and growth rate of chemically-induced murine mammary tumors, while pinealectomy or situations which implicate a reduction of melatonin production usually stimulate mammary carcinogenesis. The direct actions of melatonin on mammary tumors have been suggested because of its ability to inhibit, at physiological doses (InM), the in vitro proliferation of MCF-7 human breast cancer cells. In this article we review the outstanding findings related to melatonin actions on mammary which, taken together, support a possible usefulnes of this indoleamine in the prevention and treatment of mammary gland malignancy.
Open Access
Pathophysiology of primary hyperparathyroidism
(Murcia : F. Hernández, 2000) Hellman, P.; Carling, T.; Rask, L.; Akerstrom, G.
Parathyroid gland is the overall regulatory organ within the systemic calcium homeostasis. Through cell surface bound calcium-sensing receptors external calcium inversely regulates release of parathyroid hormone (PTH). This mechanism, which is voltage independent and most sensitive around physiologic calcium concentrations, is regulated through a 120 kDa calcium sensing receptor, CaR. Inherited inactivation of this receptor is the cause for familial hypocalciuric hypercalcemia (FHH). Parallel research identified the 550 kDa glycoprotein megalin, which also is expressed on the parathyroid cell surface, as another potential calcium sensing protein. Although this protein expresses numerous calcium binding sites on its external domain, its main function may be calcium sensitive binding and uptake of steroid hormones, such as 25-OH-vitamin Dg (bound to vitamin D binding protein) and retinol. In hyperparathyroidism (HPT), excessive PTH is secreted and the calcium sensitivity of the cells reduced, i.e. the set-point, defined as the external calcium concentration at which half-maximal inhibition of PTH release occurs, shifted to the right. Pathological cells have reduced expression of both CaR and megalin, and reduced amount of intracellular lipids, possibly including stored steroid hormones. A number of possible genetic disturbances have been identified, indicating multifactorial reasons for the disease. In postmenopausal women, however, the individual group with highest incidence of disease, a causal relation to reduced effect of vitamin D is possible. An incipient renal insufficiency with age, lack of sunshine in the Northern Hemisphere, and an association to the baT haplotype of the vitamin D receptor supports this theory. This review summarizes data on regulation of PTH release, dysregulation in HM; as well as proliferation of parathyroid cells.
Open Access
Morphological changes to somatotroph cells and in vitro individual GH release, in male rats treated with recombinant human GH
(Murcia : F. Hernández, 2000) Jiménez Reina, L.; Cañete, R.; Cepeda, T.; Bernal, G.
The effect of in vivo chronic administration of recombinant human growth hormone (rhGH) on morphology and individual GH release in somatotroph cells was evaluated in young male Wistar rats. Over an 18-day period, 30-day-old male rats were injected daily with 1.5 1U rhGH/kg (GPG group) or saline (VPG group) by subcutaneous injection. Electron-immunocytochemical, ultrastructural and morphometric studies of somatotroph cells were carried out. Additionally, rat pituitary cells were dispersed and overall and individual GH release was studied by radioimmunoassay and cell immunoblot assay (quantified by image analysis), respectively. The ultrastructure and size of somatotroph cells did not change, but volume density of secretion granules was reduced (pc0.01) by previous in vivo GH treatment. At four days, basal GH release of rat pituitary cell monolayer cultures was lower in the GPG group than in the VPG group (pc0.05); after 12 hours of culture, GHRH stimulation of GH release was lower in the GPG group than in the VPG group (p<0.05), and GHRH+SRIH inhibited GH release in the GPG group (p<0.05), but not in the VPG group. The percentage of somatotroph cells was not modified, but the ratio of strongly/weakly GH-immunostained cells had changed; weakly GH-immunostained cells increased from 34% to 55%. Moreover, in vitro treatment with GHRH, SRIH, and both, easily changed the strongly/weakly GHimmunostained cell ratio. Individual GH release, however, was not changed by previous in vivo GH treatment, although GHRH preferably stimulated a subpopulation of GH cells and SRIH did not inhibit individual GH release. These data suggest that exogenous chronic rhGH treatment down-regulates somatotroph function by modifying the proportion of GH cell subpopulation.
Open Access
Duodenal endocrine cells in mice with particular regard to age-induced changes
(Murcia : F. Hernández, 2000) Sandstrom, O.; El-Salhy, M.
Duodenal endocrine cell types in four age groups of NMRI mice (1, 3, 12 and 24 months old) were identified by immunocytochemistry and quantified by computerized image analysis. Whereas the number of secretin-immunoreactive cells was significantly increased in the 24-month-old group, the number of GIP-immunoreactive cells was reduced in 12-month-old compared with 3-month-old mice. The number of somatostatin-immunoreactive cells was fewer in both the 12- and 24-month-olds vis-a-vis the 3-month-old mice. Whereas serotonin-immunoreactive cells were fewer in both 1-month-old and 12-month-old mice, they were more numerous in 24-month-old mice then in the 3- month-old ones. The number of gastrin/CCK-immunoreactive cells was unaffected by age. The cell secretory index (CSI) of secretin- and serotonin-immunoreactive cells was increased in the 24-month-old mice vis-a-vis the 3-month-old ones and the CSI of GIP- and somatostatin-immunoreactive cells was increased in 12- month-old mice vis-a-vis 3-month-old rnice. In contrast, the CSI of somatostatin- and serotonin-immunoreactive cells in 1-month-old mice was lower than that of 3- month-old-mice. The nuclear volume of secretin-, GIP-, gastrin/CCK- and serotonin-immunoreactive cells was less in 1-month-olds than in 3-month-old mice. Whereas the nuclear volume of somatostatin-immunoreactive cells was decreased in 12-month-old animals, that of gastrin/CCK- and serotonin-immunoreactive cells was greater in 24-month-old mice than in 3-month-old ones. It is concluded that these changes may be secondary to structural and functional changes in the gastrointestinal tract caused by ageing. It is possible that these changes are involved in the development of dysfunction of the gut observed at advanced age.
Open Access
Characterization of inflammatory reaction in upper airways of cystic fibrosis patients
(Murcia : F. Hernández, 2000) Lesprit, E.; Escudier, E.; Roger, G.; Pruliere, V.; Lenoir, G.; Reinert, Ph.; Coste, A.
Inflammatory cell populations have not been yet precisely evaluated in cystic fibrosis (CF) airways. We intended to characterize morphological modifications, inflammatory cell infiltration and cell proliferation in nasal tissues obtained from 15 CF patients and from 6 non-CF patients with nasal polyposis. Morphological analysis showed an intense inflammatory infiltration in CF and non-CF tissues with only few modifications in the epithelium from CF tissues. Inflammatory cell populations characterized by specific immunolabeling were quantified, showing a predominance of macrophages and T- and B-lymphocytes and only moderate numbers of neutrophils in CF tissues; in non-CF polyps, lymphocytes and eosinophils were abundant. Proliferating cell percentages quantified after proliferating cell nuclear antigen immunolabeling were 5.3+4.1% (mean t SD) in CF polyps and 3.1?1.2% in non-CF polyps in epithelium but were very low in lamina propria. Intense inflammation in nasal tissues from CF patients is therefore dominated by macrophages and lymphocytes rather than by neutrophils. While morphology is preserved, proliferation is high in epithelium from CF polyps. These findings should be regarded in the future for a better understanding of inflammation in CF airway disease.
Open Access
Expression of c-kit and kit-ligand in benign and malignant prostatic tissues
(Murcia : F. Hernández, 2000) Simak, R.; Capodieci, P.; Cohen, D.W.; Fair, W.R.; Scher, H.; Melamed, J.; Drobnjak, M.; Heston, W.D; Stix, U.; Steiner, G.; Cordon-Cardo, C.
The tyrosine kinase receptor c-kit and its ligand [kit ligand (KL) or stem cell factor (SCF)] exert a broad range of biological activities during organogenesis and normal cell development. Recent studies have revealed that altered c-kit levels occur in a variety of malignancies and cancer cell lines. KL has also been shown to stimulate the growth of malignant cells, as well as to promote chemotaxis. We had previously reported expression of KL in stroma cells of normal human prostate. The present study was undertaken in order to analyze the patterns of expression of c-kit and KL in a well characterized set of prostatic tissues, including normal prostate (n=4), benign prostatic hyperplasia (BPH) (n=53) and adenocarcinoma (n=46) samples. The distribution of c-kit and KL proteins was studied by immunohistochemical analyses, while transcript levels were determined by in situ hybridization with specific RNA probes on a subset of the benign and malignant tissues referred above. In addition, reverse-transcriptase polymerase chain reaction (RT-PCR) was performed to determine levels of c-kit and KL expression in cultures of epithelial and stroma cells, as well as in the prostate cancer cell lines LNCaP, DUI45 and PC3. c-kit protein in normal prostate was exclusively detected in mast cells by immunohistochemistry and in situ hybridization. However, c-kit transcripts, but not ckit protein, were detected in low levels and with an heterogeneous pattern in basal epithelial cells of ducts and acini. c-kit in BPH was detected in epithelial cells in 9 of 53 (17%) specimens. c-kit protein expression in malignant epithelial cells was identified in 1 of 46 (2%) tumors. However, c-kit transcripts were detected in low levels by in situ hybridization in most of the tumors analyzed. KL protein and transcripts in normal prostate were detected in high levels in stroma cells. However, epithelial cells were unreactive for anti-KL antibody, but Offprint requests to: Dr. Carlos Cordon-Cardo, MD, PhD, Department of Pathology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue New York, NY 10021, USA. Fax: 212-794-3186. e-mail: cordonc@ mskcc.org showed low levels of KL transcripts mainly in cells of the basal layer. Basal epithelial cells in hyperplastic glands showed KL expression in 13 of 53 (24%) specimens. KL protein in tumor cells was noted in 18 of 46 (39%) cases. c-kit transcripts were not found in normal prostate and in the 3 cancer cell lines analyzed by RT-PCR, however, it was present in cultured epithelial cells of BPH, and in cultures of stroma cells from both normal and BPH. The majority of cultured cell lines of epithelial and stromal origin displayed considerable levels of KL. In addition all prostate cell lines studied showed significant levels of KL transcripts. In summary, CO-expression of c-kit and KL in a subset of BPH cases may suggest an autocrine mode of signaling. Data from this study reveals that altered patterns of c-kit and KL expression are associated with BPH and adenocarcinoma of prostate. It appears that KL induces mast cells proliferation and maturation and enhances their release of protease. This could explain the accumulation of mast cells at tumor sites. a phenomenon that was not observed in normal prostate or BPH samples.
Open Access
lntraepidermal free nerve fiber endings in the hairless skin of the rat as revealed by the zinc iodide-osmium tetroxide technique
(Murcia : F. Hernández, 2000) Müller, T.
The nerve fiber distribution in the epidermis of the hairless rat skin was studied light microscopically by means of zinc iodide-osmium tetroxide staining. Two different morphological types of free nerve fiber endings could be detected: clusters of relatively thick nerve fibers stretched up through the spinous layer up to the granular layer sending off terminal branches. In addition, many solitary thin varicose nerve fibers were seen within the epidermis. The observed discrepancies in nerve fiber diameters appeared to be larger than those reported for human intraepidermal nerve fibers in recent immuno- - histochemical studies. Moreover, dendritic cells, most probably representing Langerhans cells, could be selectively stained. These cells appeared to be in a close location to thin varicose nerve fibers. Both types of demonstrated free nerve endings have to be functionally connected with different sensoric functions. Possibly, a subpopulation of the thin nerve fibers might possess primarily a nociceptive task, whereas the thick ones have most probably to be regarded as mechanoreceptive. The nerve fibers innervating dendritic cells appear to be identical to the peptidergic ones which may regulate the antigen-presenting capacity of these cells. Due to its selectivity for intraepidermal nerve fibers, the used method might supplement immunohistochemical procedures in a helpful manner.
Open Access
Abnormal distribution of CD45 isoforms expressed by CD4+ and CD8+ T cells in rheumatoid arthritis
(Murcia : F. Hernández, 2000) Mamoune, A.; Durand, V.; Le Goff, P.; Pennec, Y.L.; Youinou, P.; Le Corre, R.
CD45RO+ T cells are referred to as memory or helper-inducer while CD45RA+ T cells are regarded as naive or suppressor-inducer T cells. The former population predominates in the peripheral blood and even more in the synovial fluid of patients with rheumatoid arthritis, to the expense of the latter population. Within the CD45RB+ compartment, there appears to be more of the fully-differentiated than of the early-differentiated CD4+ T cells. In spite of the fact that these lymphocytes are close to undergoing apoptosis, this programmed cell death is inhibited in the rheumatoid synovium.
Open Access
Prolonged kallikrein inhibition does not affect the basal growth and secretory capacity of rat adrenal cortex, but enhances mineralo- and glucocorticoid response to ACTH and handling stress
(Murcia : F. Hernández, 2000) Rebuffat, P.; Neri, G.; Bahgelioglu, M.; Malendowicz, L.K.; Nussdorfer, G.G.
The effects on the pituitary-adrenocortical functions of the prolonged (7-day) blockade of endogenous bradykinin (BK) synthesis, obtained by the administration of the kallikrein inhibitor (K-I) cyclohexylacetyl-Phe-Arg-Ser-Val-Gln amide, were investigated in the rat. K-I treatment did not cause significant changes in the (i) body and adrenal weights; (ii) basal plasma levels of ACTH, aldosterone and corticosterone; and (iii) average volume of adrenocortical cells and their basal secretory capacity. Conversely, K-I administration induced a significant magnification of the in vivo mineralo- and glucocorticoid responses to the intraperitoneal (i.p.) bolus injection of ACTH. Moreover, K-I-treated rats, but not control ones, displayed a moderate and short-term adrenal secretory response to the mild stress evoked by the placebo i.p. injection. Collectively, these findings rule out the possibility that endogenous BK plays a relevant role in the control of adrenocortical function under basal conditions. However, they suggest that endogenous BK may be involved in quenching exceedingly high adrenocortical responses to ACTH and stresses.
Open Access
Freeze-fracture cytochemistry,a new fracture-labeling method for topological analysis of biomembrane molecules
(Murcia : F. Hernández, 2000) Takizawa, T.; Robinson, J.M.
Freeze-fracture cytochemistry allows visualization of cellular and molecular characteristics of biomembranes in situ. In this review, we discuss freezefracture cytochemistry with special reference to a new cytochemical labeling of replicas, the detergentdigestion fracture-labeling technique. In this procedure, unfixed cells are rapidly-frozen, freeze-fractured, and physically stabilized by evaporated platinum/carbon. The frozen cells are then removed from the freezefracture apparatus to thaw and are subsequently treated with detergents. After detergent-digestion, replicas are labeled with cytochemical markers. We demonstrate that the technique is a versatile tool for direct analysis of the macromolecular architecture of biomembranes and allows identification of particular intracellular membrane organelles. In addition, we demonstrate the application of ultrasmall gold to freeze-fracture immunocytochemistry. Freeze-fracture cytochemistry is a valuable technique for investigating topology and dynamics of membrane molecules.
Open Access
Linkage between cell membrane proteins and actin-based cytoskeleton the cytoskeletal-driven cellular functions
(Murcia : F. Hernández, 2000) Fais, S.; Luciani, F.; Logoui, M.; Parlato, S.; Lozupone, F.
Asymmetric organization of the plasma membrane and cytosolic organelles is fundamental for a variety of cells, including bacteria, yeast and eukaryotic cells (Nelson, 1992). The degree into which cells polarize is characterized by their ability to create and maintain morphologically and biochemically distinct plasma membrane domains. The generation and maintenance of polarized distribution of membrane components (proteins and lipids) is thus critical to the ability of cells to perform complex activities such as cell-to-cell interactions, vectorial transport and secretion, cellular immunity, development and morphogenesis. Modification of cellular polarity may potentially lead to abnormal cellular activities and various pathological disorders (Molitoris, 1991; Carone et al., 1994; Chen et al., 1995). Our review shows the complex interplay between membrane proteins and the cytoskeletal network in determining the "polarized phenotype" in the cell. We provide evidence that membrane/cytoskeleton interaction is the key to regulation of the vast majority of cellular functions.
Open Access
Cellular localization of fibroblast growth factor 2 , FGF,-2 in benign prostatic hyperplasia
(Murcia : F. Hernández, 2000) Sinowatz, F.; Schams, D.; Einspanier, R.; Arnold, G.; Pfeffel, M.; Temmim-Bakers, L.; Amselgruber, W.; Plendl, J.
Fibroblast growth factor 2 (FGF-2, basic fibroblast growth factor) has been reported to be elevated in tissues from benign prostatic hyperplasia (BPH), the most frequent neoplastic disease in aging men. This suggests that FGF-2 may play a significant role in the development of BPH. In this study the cellular distribution pattern of FGF-2 in tissues from BPH has been investigated by immunohistochemical and molecular biological methods. Radioimmunoassay revealed high concentrations of FGF-2, ranging between 450 and 950 ng per g tissue. Immunoblots confirmed the presence of a 18 kDa FGF-2 in tissue extracts. By immunohistochemistry done with a polyclonal antibody to recombinant FGF-2 on paraffin sections, FGF-2 was localized in fibroblasts, endothelial cells and smooth muscle cells of tissue samples of BPH. Nuclei of these cells were labelled distinctly. Moreover the cytoplasm of smooth muscle cells was labelled moderately. No immunostaining was seen in prostatic epithelium. Nonradioactive in situ hybridization with digoxygeninlabelled oligonucleotides revealed the presence of mRNA for FGF-2 in smooth muscle cells of the prostatic stroma. These results provide evidence that FGF-2 may be produced locally in the human prostate as a stromaspecific mitogen and may play a causal role in the development of BPH.
Open Access
Gain of function properties of mutant p53 proteins at the mitotic spindle cell cycle checkpoint
(Murcia : F. Hernández, 2000) Hixon, M.L.; Flores, A.; Wagner, M.; Gualberto, A.
Mutations in the p53 tumor suppressor gene locus predispose human cells to chromosomal instability. This is due in part to interference of mutant p53 proteins with the activity of the mitotic spindle and postmitotic cell cycle checkpoints. Recent data demonstrates that wild type p53 is required for postmitotic checkpoint activity, but plays no role at the mitotic spindle checkpoint. Likewise, structural dominant p53 mutants demonstrate gain-of-function properties at the mitotic spindle checkpoint and dominant negative properties at the postmitotic checkpoint. At mitosis, mutant p53 proteins interfere with the control of the metaphase-toanaphase progression by up-regulating the expression of CKsl, a protein that mediates activatory phosphorylation of the anaphase promoting complex (APC) by Cdc2. Cells that carry mutant p53 proteins overexpress CKsl and are unable to sustain APC inactivation and mitotic arrest. Thus, mutant p53 gain-of-function at mitosis constitutes a key component to the origin of chromosomal instability in mutant p53 cells.
Open Access
Schwann cell extracellular matrix molecules and their receptors
(Murcia : F. Hernández, 2000) Chernousov, M.A.; Carey, D.J.
The major cellular constituents of the mammalian peripheral nervous system are neurons (axons) and Schwann cells. During peripheral nerve development Schwann cells actively deposit extracellular matrix (ECM), comprised of basal lamina sheets that surround individual axon-Schwann cell units and collagen fibrils. These ECM structures are formed from a diverse set of macromolecules, consisting of glyco-proteins, collagens and proteoglycans. To,interact with ECM, Schwann cells express a number of integrin and non-integrin cell surface receptors. The expression of many Schwann cell ECM proteins and their receptors is developmentally regulated and, in some cases, dependent on axonal contact. Schwann cell ECM acts as an organizer of peripheral nerve tissue and strongly influences Schwann cell adhesion, growth and differentiation and regulates axonal growth during development and regeneration.
Open Access
Id genes in nervous system development
(Murcia : F. Hernández, 2000) Andres-Barquin, P.J.; Hernandez, M.C.; Israel, M.A.
Id genes encode helix-loop-helix proteins that function to mediate processes important for normal development including cellular differentiation. proliferation and apoptosis. Id proteins act as negative regulators of other transcription factors, which are essential for cell determination and differentiation in diverse cell types, and interact with proteins important for cell cycle regulation. Studies of Id gene expression in the nervous system and in neural cells in culture indicate that Id proteins contribute to the regulation of mammalian nervous system development. Also, recognition of a wide variety of proteins with which Id transcription factors are capable of interacting suggests that it will be possible to understand more precisely their specific functions and importantly how these are integrated.
Open Access
Skeletal muscle development in the mouse embryo
(Murcia : F. Hernández, 2000) Kablar, B.; Rudnicki, M.A.
n this review we discuss the recent findings concerning the mechanisms that restrict somitic cells to the skeletal muscle fate, the myogenic regulatory factors controlling skeletal muscle differentiation and specification of myogenic cell lineages, the nature of inductive signals and the role of secreted proteins in embryonic patterning of the myotome. More specifically, we review data which strongly support the hypothesis that Myf-5 plays a unique role in development of epaxial muscle, that MyoD plays a unique role in development of hypaxial muscles derived from migratory myogenic precursor cells, and that both genes are responsible for development of intercostal and abdominal muscles (hypaxial muscles that develop from the dermatomal epithelia). In addition, while discussing upstream and post-translational regulation of myogenic regulatory factors (MRFs), we suggest that correct formation of the myotome requires a complex cooperation of DNA binding proteins and cofactors, as well as inhibitory function of non-muscle cells of the forming somite, whose proteins would sequester and suppress the transcription of MRFs. Moreover, in the third part of our review, we discuss embryonic structures, secreted proteins and myogenic induction. However, although different signaling molecules with activity in the process of somite patterning have been identified, not many of them are found to be necessary during in vivo embryonic development. To understand their functions, generation of multiple mutants or conditional/tissue-specific mutants will be necessary.
Open Access
Neonatal treatment with monosodium glutamate MSG structure of the TSH-immunoreactive pituitary cells
(Murcia : F. Hernández, 2000) Miskowiak, B.; Partyka, M.
Glutamic acid represents the most abundant stimulatory neurotransmitter in the central nervous system. Monosodium glutamate (MSC), subcutaneously administered to newborn rats in the perinatal period, induces lesions in 80 to 90% of the neurocytes of arcuate nuclei in the hypothalamus. These nuclei are the site of production of numerous stimulatory and inhibitory hormones including growth hormone releasing hormone (GHRH). The present studies were performed on male Wistar strain rats, subcutaneously injected on days 2, 4, 6, 8, and 10 of postnatal life with MSC at a dose of 4 mglg body weight. Eighteen-month-old rats were additionally treated with Ambinon. When the animals reached the ages of 6 or 12 months, their body weight, body length and weight of pituitary were determined. On parafrin sections, using imrnunohistochemical techniques, TSHimmunoreactive cells were detected and characterised by computerised image analysis. The results were subjected to statistical analysis using Student's t test. The rats which were perinatally treated with MSC and examined after 6 or 12 months of life were obese and shorter than control rats by 7% and 10% respectively. They also exhibited a reduction in the weight of the pituitary of 30% and 40% respectively in the two age groups. The proportion of TSH-immunoreactive cells in the pituitary remained unchanged and amounted to 4.5% in the 6-month-old and 5.4% in the 12-month-old rats respectively. The number of TSH-positive cells per mm 2 area remained unchanged. The area and circumference of the cells in the 12-month-old rats were reduced by 22% and 18%, respectively. Perinatal injury to hypophyseal arcuate nuclei induced by monosodium glutamate injection, was not associated with any significant alterations in pituitary structure, as defined by the proportion of pituitary volume occupied by TSH-immunoreactive cells.