PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Cellular differentiation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 667 records · Page 37Linked to original sources
PubMed1982

[Cellular differentiation processes in normal squamous epithelium and initial stages of cervical neoplasia].

Nuclear size and ratio between DNA and nucleus were measured in 787 normal, pseudo-dyskaryotic and dyskaryotic cells of superficial and intermediary layers obtained from condylomatous lesions as well as from cases of atypical metaplasia and slight dysplasia, following Feulgen staining of the cytological specimens. All cell types occurred at different periods of time, as was observed in a longitudinal-section study. This, together with the data measured, was likely to suggest the biphasic nature of changes in cell nuclei, in that initially functional nuclear oedema (pseudo-dyskaryosis) was followed by differentiation towards the dyskaryotic cell. These processes were found to occur first to superficial cells and second to intermediary cells. In the phase of intermediary dyskaryosis the quantity of DNA was increased with significance by polyploidisation. All six cell populations differed from one another with significance by nuclear surface.

Cell Differentiation↗
PubMed1994

Differential cellular expression of cystic fibrosis transmembrane regulator in human reproductive tissues. Clues for the infertility in patients with cystic fibrosis.

Cystic fibrosis (CF) is characterized by a wide spectrum of clinical manifestations, including reproductive problems. Practically all males affected by the disease are infertile due to azoospermia associated with pathology of the male ducts, whereas females with CF have reduced fertility. To study the mechanism of reproductive pathology in CF patients, we analyzed the levels and localization of expression of the cystic fibrosis transmembrane regulator (CFTR) gene in relevant postnatal tissues. Significant expression was detected in the epithelium of the epididymis and vas deferens. Minimal expression, not associated with specific cell types, was seen in the mature testis. In female genitalia, variable levels of expression were seen in the cervical epithelium and fallopian tube. The endometrial epithelium and glands expressed CFTR at high levels only after puberty. No expression was seen in ovaries. Deficient secretory function of CFTR in males but not in females may lead to organ damage probably as a consequence of excessive concentration of viscid luminal contents.

Adult↗
PubMed1995

Differential cellular expression of the human MSH2 repair enzyme in small and large intestine.

The human MSH2 (hMSH2) protein is responsible for the initial recognition of mismatched nucleotides during the postreplication mismatch repair process. Loss of hMSH2 function has been demonstrated to lead to the accumulation of replication errors, resulting in a mutator phenotype, which may be responsible for the multiple mutations required for multi-stage carcinogenesis. Alterations of the hMSH2 gene has been linked to approximately 60% of hereditary nonpolyposis colon cancer cases. Colon tumors in hereditary nonpolyposis colon cancer patients originate within benign preneoplastic adenomas and display replication errors in the form of microsatellite instability. The aim of this study was to investigate the cellular expression of the hMSH2 protein in cells of the large and small intestines. Using antibody specific for hMSH2, we have determined that this protein is highly expressed in cells of the crypts of Lieberkühn that are undergoing rapid renewal in both the ileum and colon. Proliferative perifibroblasts in the colon also showed significant presence of the hMSH2 protein. These results confirm the hypothesis that hMSH2 is expressed in highly proliferative cells of the gut, and mutations in this gene could, therefore, be expected to expedite the progression of adenoma to carcinoma in this tissue.

Animals↗
PubMed1994

[Genetic control of cellular differentiation and proliferation during gametogenesis in mammals].

Understanding the genetic program that controls the regulation of cells progressing through the mitotic and meiotic cell cycles, whether in response to growth factors, other extracellular signals, or intrinsic programs, is critical to problems in infertility and in gonadal neoplasias. In this study, we present a consideration of important stages of cell cycle control in mammalian germ cells and data illustrating the experimental approaches that can be used to determine the pattern of such genes which may be involved in these events.

Animals↗
PubMed1994

Marked apoptosis of human myelomonocytic leukemia cell line P39: significance of cellular differentiation.

Myelodysplastic syndrome (MDS)-derived leukemia cell line P39/Tsugane could be induced to apoptosis by a variety of agents including metabolic inhibitors, a calcium ionophore and differentiation-inducing agents. As evaluated by characteristic morphological changes and oligonucleosomal lengths DNA ladder, the levels of apoptosis in P39 cells induced by actinomycin D, or A23187, were far greater than in other myeloid lines examined in this study. When 22-oxa-1 alpha, 25(OH)2D3 (D3), dimethyl sulfoxide (DMSO) and all-trans retinoic acid (RA) were used as differentiation-inducers, varying degrees of apoptosis were seen. D3 induced monocytoid differentiation, but not apoptosis above the control level. On the other hand, RA induced profound apoptosis concomitant with the progressive expression of differentiation markers. Studies on morphology, functions and phenotypes of P39 cells exposed to differentiation inducers suggest that the incidence of apoptosis was not affected by the process of differentiation, but cells in the process of varying degrees of differentiation may die via apoptosis. Moreover, RA-treated P39 cells are unique in the simultaneous occurrence of profound apoptosis and differentiation. We propose that RA-treated P39 differentiation model is ideally suited for the study of MDS.

Apoptosis↗
PubMed1993

Suppression of a cellular differentiation program by phorbol esters coincides with inhibition of binding of a cell-specific transcription factor (NF-E2) to an enhancer element required for expression of an erythroid-specific gene.

Induction by hemin increases, while induction with 12-O-tetradecanoylphorbol-13-acetate (TPA) represses, erythroid-specific gene expression in the human cell line K562. We analyzed the effects of hemin or TPA induction on the binding and activity of transcription factors at a regulatory element found within the transcriptional regulatory sequences of many erythroid-specific genes. TPA induction increases the binding of ubiquitous AP-1 factors to this element. TPA induction inhibits the binding of the lineage limited transcription factor NF-E2 to this transcriptional control element. Hemin induction of K562 cells does not facilitate the binding of NF-E2 to its recognition site. Hemin induction appears to nonspecifically increase the expression of transiently transfected genes in K562 cells. Beyond this nonspecific increase in gene expression, hemin induction acts to increase the activity of the lineage limited transcription factor NF-E2. The divergent effects of hemin and TPA on gene expression in K562 cells are mediated, in part, by their contrasting effects on the transcription factor NF-E2.

Base Sequence↗
PubMed1995

Differential cellular and subcellular expression of the human multifunctional apurinic/apyrimidinic endonuclease (APE/ref-1) DNA repair enzyme.

The multifunctional mammalian apurinic/apyrimidinic endonuclease (APE) is responsible for the repair of apurinic/apyrimidinic sites in DNA. In addition, this enzyme has been shown to function as a redox factor facilitating the DNA-binding capability of JUN and FOS, as well as numerous other transcription factors through the alteration of the transcription factor redox state. Biochemical studies of organ homogenates have shown that APE is present in the different tissues studied at similar concentrations. The present study examines the immunohistochemical distribution of APE in several organs and demonstrates new and unexpected patterns of cellular and subcellular localization of this enzyme. In the hippocampus, the APE protein was highly expressed in neurons of the dentate gyrus and regions CA3 and CA4, and unexpectedly, the staining was primarily cytoplasmic. AP endonuclease immunoreactivity in the cerebellum was found in the granule and Purkinje cells, both cytoplasmic and nuclear. APE staining of the hypoglossal nucleus of the brainstem, where motor neurons that control tongue movement reside, showed reactivity in the cytoplasmic Nissl substance. Skin, liver, and duodenum demonstrated nuclear staining; however, in the duodenum, only the enterocyte nuclei of the proximal villus and the crypts of Lieberkuhn were stained, with no staining of the distal villus. These results suggest that APE has different regulatory and functional roles in different cells and organs of the body. This study shows the importance of correlating in vitro findings in tissue culture cells with the organism as a whole. The cytoplasmic staining seen in parts of the brain and in liver suggests that there may be additional functions for the APE yet to be described.

Autopsy↗
PubMedDate not supplied

Hepatocellular carcinoma in young patients: histology, cellular differentiation, HBV infection and oncoprotein p53.

The study of 226 cases of hepatocellular carcinoma (HCC) in a homogenous rural Southern African population is based on the assessment of histology, HBV infection, p53 oncoprotein and transforming growth factor alpha (TGFa) expression. Epidemiological and morphological observations were compared to HCC observed in 89 cases from pathological files in Poland and published information from Japan and Italy. Comparatively high number of young patients with HCC in Africa presented high rates of HBV infection, p53 oncoprotein overexpression and high HBsAg/p53 correlation rates. In all patients histological grading of HCC was inversely related to p53 and TGFa expression. No significant differences in histological grading of HCC and patients' mean age were noted between various population groups. The association of hepatic cirrhosis was at least twice as common in non-African patients, whereas iron overload was noted almost exclusively in African patients livers. Signs of HBV infection were lowest in Japanese female patients. The mechanism by which early HBV infection contributes to hepatocarcinogenesis at an early stage of life is confirmed by epidemiological observations in Poland and by the clear association of p53 gene with HBsAg and the age of patients.

Adolescent↗
PubMed1998

Receptor for advanced glycation endproducts (RAGE) exhibits highly differential cellular and subcellular localisation in rat and human lung.

The transmembrane receptor (RAGE) of advanced glycation endproducts (AGEs), is abundantly present in the lung. Although the interaction of AGEs and RAGE plays an important role in vasculopathies, particularly in diabetes, the lung is not a classical target organ of diabetes. Thus, the role of RAGE in the lung is still obscure. This study sought to precisely localise RAGE in the lungs of rat and human by immunohistochemistry, double immunofluorescence and immunoelectron microscopy using a polyclonal antiserum developed against human recombinant RAGE. Anti-RAGE immunoreactivity was prominent in alveolar epithelial type I pneumocytes, while it was absent from type II pneumocytes and capillary endothelium. Cell type specificity was demonstrated by colocalisation with well established cell markers. Quantitative immunoelectron microscopy of cryo-substituted, Lowicryl-embedded rat and human specimens demonstrated a unique labelling pattern of RAGE in that it selectively localised to the basal cell membrane of type I pneumocytes. Labelling pattern was independent of the mode of fixation. Equivalent labelling densities were calculated from a fibrotic rat lung 3 months after irradiation. This highly selective localisation of RAGE to the basal face of type I pneumocytes and its absence from capillary endothelium might explain the resistance of the lung to typical diabetic complications.

Animals↗
PubMed2000

Analysis of gene expression profile during 3T3-L1 preadipocyte differentiation.

Cellular differentiation is a process in which a group of differentiation specific genes is programmatically induced. This gene expression program leads to changes in both cellular morphological and physiological phenotypes. Using an 18,376-member cDNA/EST microarray, we analyzed the difference in gene expression profiles between differentiated 3T3-L1 adipocyte and non-differentiated 3T3-L1 preadipocyte. From our study a large number of genes and ESTs were identified as differentially induced or suppressed. In this paper we describe the changes of gene expression profile during 3T3-L1 cell differentiation.

3T3 Cells↗
PubMed2003

[Cellular lipid dynamics].

During the past years, the notion of microdomains at the surface of cellular membranes has been developed. These are constituted by lipid rafts which involve sphingoglycolipids and cholesterol. To these rafts are associated proteins which have a lipid anchor or are transmembrane proteins. These lipid rafts target specific proteins at the plasma membrane surface and can remain associated with them. They are present in surface receptors and endocytosis occurs upon binding of the specific ligands. Thus these rafts participate to major aspects of cellular dynamics. These rafts are complex structures, insoluble in non-ionic detergents. According to the detergent used, many types of rafts can be isolated. Any alteration of cholesterol, sphingoglycolipids, or abnormalities of the proteins themselves, can lead to abnormal targeting at the membrane surface. It is possible that specific sphingoglycolipids are necessary to target specific proteins at the membrane surface. This may explain the complexity of the sphingoglycolipid molecules, both in relation to their oligosaccharide and to their ceramide structures. There is both a cellular and a tissue specificity of these constituents. Complex sphingoglycolipids are involved in cellular differentiation, cellular polarization, and modified in relation to cancer. Virus and bacteria can be linked to the sphingoglycolipids of these microdomains and alter cellular signaling and function. Sphingoglycolipids are involved in autoimmune diseases as antibody targets and in neurolipidoses which are genetic diseases involving their catabolism. The dynamics of the lipid rafts, in relation to cholesterol, can be altered in Niemann-Pick's disease type C and in Alzheimer's disease. Thus these microdomains are involved in many aspects related to normal and pathological cellular dynamics.

Animals↗
PubMed1999

Embryonic electronics.

Within the general domain of bio-inspired computing, a particular trend over the past few years has been that of constructing actual hardware devices that are inspired by nature. This paper describes one such project-Embryonics (embryonic electronics)-inspired in particular by the process of embryogenesis. Our ultimate objective is the construction of large-scale integrated circuits, exhibiting the properties of self-repair (healing) and self-replication, found until now only in living beings. We present the silicon-based artificial cell, followed by a description of mechanisms operating at the cellular level: cellular differentiation, cellular division, regeneration, and replication. We then present the cell's composition as an ensemble of lower-level elements, known as 'molecules'. As electronic chips grow evermore complex, the need for self-repair capabilities will become increasingly crucial. The Embryonics approach represents one possible way of confronting this pivotal problem.

Cell Differentiation↗