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At least 145 records · Page 8Linked to original sources
PubMed1994

The neurons of the medial geniculate body in the mustached bat (Pteronotus parnellii).

The neurons in the medial geniculate body were studied in Golgi preparations from adult mustached bats (Pteronotus parnellii). Their somatic and dendritic configurations were compared with those of cells in other, nonecholocating mammals. A second goal was to use the thalamic nuclear subdivisions derived from Golgi material to integrate the findings in parallel studies of cytoarchitecture, immunocytochemistry, and tectothalamic connections. Three primary divisions are defined. The ventral division is large and has a stereotyped neuronal organization. Medium-sized perikarya (about 10 microns in diameter) represent tufted neurons; the fibrodendritic plexus forms laminae in the lateral part along which midbrain axons terminate. A smaller, possibly intrinsic, neuron with thin, sparse dendrites is rarely impregnated. Neurons in the larger, medial part, which represents frequencies of 60 kHz and higher, have more spherical dendritic fields; their branching pattern remains tufted, and the laminar organization was less evident. The dorsal division is about equal in size, and it has many nuclei and a corresponding neuronal diversity. These neurons are medium-sized except in the suprageniculate nucleus, where many cells are larger. Four dorsal division nuclei are recognized. Each has neurons with radiate or weakly tufted dendritic arbors. Superficial dorsal nucleus neurons are oriented from medial to lateral, imparting a slightly laminated appearance to the neuropil. A few smaller, stellate neurons with modest dendritic domains are present. Suprageniculate nucleus neurons have radiating dendritic fields that project spherically; they have fewer branches than dorsal nucleus neurons. The posterior limitans nucleus is dorsomedial to the suprageniculate nucleus; it has small neurons with long, sparsely branched dendrites. The rostral pole nucleus, included in the dorsal division on cytoarchitectonic grounds, had too few neurons impregnated to reveal its neuronal architecture. The medial division, the smallest of the main parts, is one nucleus with at least six types of cells, including the magnocellular, bushy tufted, disc-shaped, medium-sized multipolar, elongated, and small stellate neurons. There is no laminar arrangement. Many of the neurons resemble those in rodent, marsupial, carnivore, and primate auditory thalamic nuclei. Despite such morphological correspondences, functional differences, such as the evolution of combination sensitivity, suggest that structurally comparable auditory thalamic neurons may subserve diverse physiological representations.

Animals↗
PubMed1977

Fine structure of the ordinary lateral line organ. II. The lateral line canal organ of spotted shark, Mustelus manazo.

The lateral line organ of the spotted shark is characterized by its semi-cylindrical shape. Each organ (neuromast) is so closely apposed to the next that the individual neuromasts are almost continuous. The neuromast is composed of receptor cells, supporting cells and mantle cells. The receptor cells bear one kinocilium and up to 40 stereocilia. Bi-directional arrangement of the receptor cells as occurs in teleosts was demonstrated. Afferent and efferent nerve endings were found at the base of the receptor cells. The supporting cells extend from the basal lamina to the free surface. Long microvilli and a cilium-like "ciliary rod" project from the top of each supporting cell. The cell contains relatively few elements of the Golgi apparatus and little rough endoplasmic reticulum, but mitochondria and filaments are abundant. The mantle cell limits the lateral margin of the neuromast. It is distinguished from the supporting cell because of its long crescent-shaped nucleus and scarce, short microvilli. Myelinated nerve fibres are found in the subepithelial connective tissue but not in the epithelium. The fine structure of the shark lateral line organ suggests that this organ is in an intermediated step of evolution between that of lamphrey and teleost.

Animals↗
PubMed1985

[Sarcomatoid spindle-cell epithelioma. Anatomicoclinical study of 15 cases].

Sarcomatoid spindle cell carcinoma, which is a rather rare cancer, is of epithelial origin, but histologically resembles a connective spindle cell sarcoma. It remains subject to controversy, especially concerning the reality of epitheliomesenchymatous transformation of the neoplastic cells which, indeed, take on not only the shape but also the behaviour of connective cells. The debate is of both a dogmatic and practical nature, dogmatic in that it has bearing on the question of cellular specificity, and practical in that histological transmutation has repercussions on the macroscopic aspect of the tumor, its clinical evolution and even its behaviour vis-a-vis radiation therapy. The preferred, but not the only, sites of such tumors are the upper respiratory and digestive tracts. In many cases, they occur in subjects who many years previously had undergone radiological treatment, with the tumor appearing in the irradiated area. The problems raised by these unusual cancers explain and seem to justify the publication over the last few years of isolated cases or series of reports made in various centers. The present work concerns 15 anatomoclinical cases observed at the Institut Curie.

Adult↗
PubMed2002

Comparative analysis of ribosomal proteins in complete genomes: an example of reductive evolution at the domain scale.

A comprehensive investigation of ribosomal genes in complete genomes from 66 different species allows us to address the distribution of r-proteins between and within the three primary domains. Thirty-four r-protein families are represented in all domains but 33 families are specific to Archaea and Eucarya, providing evidence for specialisation at an early stage of evolution between the bacterial lineage and the lineage leading to Archaea and Eukaryotes. With only one specific r-protein, the archaeal ribosome appears to be a small-scale model of the eukaryotic one in terms of protein composition. However, the mechanism of evolution of the protein component of the ribosome appears dramatically different in Archaea. In Bacteria and Eucarya, a restricted number of ribosomal genes can be lost with a bias toward losses in intracellular pathogens. In Archaea, losses implicate 15% of the ribosomal genes revealing an unexpected plasticity of the translation apparatus and the pattern of gene losses indicates a progressive elimination of ribosomal genes in the course of archaeal evolution. This first documented case of reductive evolution at the domain scale provides a new framework for discussing the shape of the universal tree of life and the selective forces directing the evolution of prokaryotes.

Animals↗
PubMedDate not supplied

Research on red cell membrane permeability in arterial hypertension.

Arterial hypertension, including the elucidation of hypertension pathogenic mechanisms involving elements in the composition of the blood, continues to represent a topical research area. Recent work, such as nuclear magnetic resonance studies looking into red cell permeability, illustrates the presence of modifications of red cell permeability to water (RCPW) related to the stage of arterial hypertension. The identification of a significant increase of RCPW compared to that present in the population with normal arterial pressure values can be useful both in early diagnosis and in warning about a possible predisposition for this condition. At the same time, the dynamic investigation of protonic relaxation time of both intra- and extra-erythrocytic water, the assessment of proton exchange time across the red cell and the calculation of permeability to water enable one not only to diagnose arterial hypertension but also to ascertain the evolution of the disease, its complications and the effectiveness of anti-hypertensive medication. Our studies have also proven the existence of a correlation between the values of systolic arterial pressure and red cell permeability to water. The curve describing the interdependence of the two values has the shape of a bell, in the case of males. The peak of the curve is reached for a systolic pressure of 160 mmHg and gets below the values of the control group in the case of systolic pressures above 200 mmHg. The RCPW test can also be considered a valuable indicator in evaluating the risk of stroke in hypertensive patients. In the chronic therapy of arterial hypertension with various types of anti-hypertensive drugs, one can note differences in the RCPW values related to the effectiveness of the respective medication, to the clinical form and stage of the disease, the sex of the patient as well as to the existence of cerebro-vascular complications.

Adrenergic alpha-Agonists↗
PubMed2003

Shaping up adaptive immunity: the impact of CCR7 and CXCR5 on lymphocyte trafficking.

The effective onset of adaptive immune responses requires that naïve antigen-specific lymphocytes, being inherently rare throughout the body, rapidly encounter foreign antigens. This problem has been elegantly solved in evolution by inventing secondary lymphoid tissues as intersections in the migratory pathway of antigen-presenting dendritic cells and antigen-specific lymphocytes. Chemokines play a central role in guiding cell movements in the course of immune responses and in lymphoid system homeostasis. In particular, the chemokine receptors CCR7 and CXCR5 are key molecules for the entry of lymphocytes and dendritic cells into secondary lymphoid organs and their homing to T-cell and B-cell zones therein. CCR7 and CXCR5 are differentially expressed on the cell surface of lymphocytes and dendritic cells depending on the stage of cellular differentiation and activation, thus allowing these cells to change their homing capacity and prospective traffic routes.

Adaptation, Physiological↗
PubMed2026

Longitudinal dynamics of gene expression and metabolomics in an aging population cohort.

Multiomic profiling provides a comprehensive physiological overview at the molecular level, but understanding of its spatiotemporal dynamics remains limited in human populations. We profiled longitudinal whole-blood gene expression and metabolite levels in 335 females over 8 years. Levels of 5061 genes and 181 metabolites changed over time, with individual trajectories often diverging from population-level trends. Longitudinally variable genes showed cell type specificity and enrichment for aging-relevant pathways, including cardiometabolic and neurodegenerative disorders. Longitudinal trajectories were further shaped by genetics, circadian rhythm, seasonality, and environmental pollutant exposures. Integrative analyses revealed extensive static and time-variable cross-omic connectivity. Longitudinal profiling offers insight into the temporal evolution of age-related conditions at the molecular level, and understanding individual variation within these longitudinal patterns will be essential for future precision medicine approaches.

Female↗
PubMed1977

Comparison of vegetative anatomy of Piperales. II. Leaf.

Many characters of leaf (hair, hypodermal cells, palisade layers, intercellular space, distinction between spongy and palisade parenchyma, "palisade ratio", distribution of collenchyma and sclerenchyma, presence or absence of starch grains, calcium oxalate crystals, number, shape and arrangement of bundles of petiole) are useful distinguishing characters. Reduction of palisade layers seems to be the trend of evolution in Piper and Peperomia.

Plants↗
PubMed1996

Plant profilins rescue the aberrant phenotype of profilin-deficient Dictyostelium cells.

To characterize the function of plant profilins in vivo, we expressed two pollen specific Zea mays (maize) profilin isoforms in profilin-minus Dictyostelium discoideum mutants. In maize, profilins exist as a multigene family containing 4 or more members which are highly similar to each other but substantially less similar to profilins from animals and lower eukaryotes. Previously we have shown that D. discoideum profilin-minus cells have an aberrant phenotype due to defects in cell shape, cytokinesis, and development. These defects could be rescued by introducing the pollen-specific profilins 1 or 2 from maize using a newly constructed expression vector. Expression of the heterologous profilins in Dictyostelium clones was assayed by affinity purification of the pollen profilins with poly-proline agarose and by immunoblotting with a polyclonal antiserum raised against maize pollen profilin. In contrast to the profilin-minus mutants, Dictyostelium cells expressing plant profilins showed normal cell shape, contained less F-actin, and were able to form fruiting bodies. These data provide genetic evidence that maize pollen profilins, even though they are specific for a distinct developmental stage, share functional properties with profilin from a lower eukaryote and apparently act as G-actin-sequestering proteins in this system.

Animals↗
PubMed2002

Lamins: building blocks or regulators of gene expression?

Intermediate filament (IF) proteins are the building blocks of cytoskeletal filaments, the main function of which is to maintain cell shape and integrity. The lamins are thought to be the evolutionary progenitors of IF proteins and they have profound influences on both nuclear structure and function. These influences require the lamins to have dynamic properties and dual identities--as building blocks and transcriptional regulators. Which one of these identities underlies a myriad of genetic diseases is a topic of intense debate.

Animals↗
PubMed2002

A model of the early evolution of soma-to-germline feedback.

The V-genes of the immunoglobulin locus in vertebrates code for a part of the heavy and light chain variable regions of antibodies and are extremely variable. Steele (1979) has developed a theory that explains the evolution of adaptive immune response by a soma-to-germline flow of cDNAs derived from somatically mutated V-genes. Here we model the early evolution of soma-to-germline feedback in a population living in a changing viral environment in terms of the dynamics of an initially rare genetic modifier that controls transfer of V-genes to germ cells' DNA. It is shown that a modifier invades the population and creates a great variety of V-genes if the environment follows stepwise temporal changes, i.e. a soma-to-germline feedback machinery evolves in a population if newly derived V-alleles still play a role in protecting the population against foreign antigens in some following generations. The distribution of the age of V-genes evolves to a bell-shaped curve the width and the maximum of which depend mainly on selection strength. Two phases of modifier evolution are distinguished. In the first phase, the dynamics are slow while the number of different V-genes is small. In the second phase, when a sufficiently large number of different V-genes is created, the modifier increases faster in frequency. Linkage of V-genes and the modifier enhances the rate of evolution.

Animals↗
PubMed1986

Contributions of the Mac-1 glycoprotein family to adherence-dependent granulocyte functions: structure-function assessments employing subunit-specific monoclonal antibodies.

MAb directed at the alpha-subunits of Mac-1 (alpha M), LFA-1 (alpha L), p150,95 (alpha X), or their common beta-subunit were used to characterize the contributions of the Mac-1 glycoprotein family to granulocyte adherence reactions. Inhibitory effects of these MAb in incubation experiments with normal granulocytes indicated distinct adhesive contributions of each subunit. Significantly greater adherence, and inhibition of adherence by anti alpha M, alpha X, and beta MAb, was observed under chemotactic conditions designed to "up-regulate" the surface expression of the alpha M beta and alpha X beta complexes. Adherence to protein-coated glass and binding of albumin-coated latex beads were significantly inhibited by anti-beta greater than anti-alpha M (OKM-10, M1/70, LM2/1.6 and OKM-1) greater than anti-alpha X greater than anti-alpha L MAb, but no effects of anti-HLA, AB, or anti-CR-1 MAb were evident. A similar rank order of inhibition was observed in granulocyte aggregation assays in response to C5a, PMA, or f-Met-Leu-Phe. Significant inhibition of directed migration by anti-beta or anti-alpha M (OKM-1 or OKM-10) MAb was observed in subagarose but not Boyden chemotaxis assays; inhibition was dependent on a continuous cell exposure to anti-Mac-1 alpha or beta during the assay, suggesting that a continuum of new Mac-1 expression is required for directed translocation. Phagocytosis of Oil-Red-O paraffin or zymosan selectively opsonized with C3-derived ligands was significantly inhibited by anti-alpha M MAb (OKM-10 greater than LM2/1.6 greater than M1/70 greater than OKM-1) or by combinations of anti-alpha M + anti-CR-1 MAb, but only minimal inhibitory effects of anti-beta MAb and no effects of anti-alpha L or anti-alpha X MAb were seen. Similarly, complement-dependent phagocytosis-associated lactoferrin release, ingestion, and intracellular killing of Staphylococcus aureus 502A, and binding of iC3b-opsonized SRBC, were significantly inhibited by anti-alpha M (OKM-10, M1/70) or combinations of anti-alpha M + anti-CR-1 MAb, but not by anti-beta, alpha L, or alpha X MAb. Notably, none of the anti-Mac-1 MAb demonstrated inhibitory effects in assays of adherence-independent functions including shape change, specific f-Met-Leu-3H-Phe binding, O-2 generation, chemiluminescence evolution, or lactoferrin release in response to PMA.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1996

Salmonellosis: host immune responses and bacterial virulence determinants.

The lifestyle of bacterial pathogens requires them to establish infection in the face of host immunity. Upon entering a potential host, a variety of interactions are initiated, the outcome of which depends upon a myriad of attributes of each of the participants. In this review we discuss the interactions that occur between pathogenic Salmonella species and the host immune systems, but when appropriate to broaden perspective, we have provided a general overview of the interactions between bacterial pathogens and animal hosts. Pathogenic Salmonella species possess an array of invasion genes that produce proteins secreted by a specialized type III secretion apparatus. These proteins are used by the bacteria to penetrate the intestinal mucosa by invading and destroying specialized epithelial M cells of the Peyer's patches. This maneuver deposits the bacteria directly within the confines of the reticuloendothelial system. The host responds to these actions with nonspecific phagocytic cells and an inflammatory response as well as by activating specific cellular and humoral immune responses. Salmonella responds to this show of force directly. It appears that the bacteria invade and establish a niche within the very cells that have been sent to destroy them. Efforts are underway to characterize the factors that allow these intracellular bacteria to customize intracellular vacuoles for their own purposes. It is the constant play between these interactions that determines the outcome of the host infection, and clearly they will also shape the evolution of new survival strategies for both the bacterium and the host.

Animals↗
PubMed1998

Solitary bronchioloalveolar adenoma of the lung.

A case of an unusual pulmonary neoplasia, called bronchioloalveolar adenoma of the lung, is reported. The neoplasm presented as a solitary peripheral lesion of the left lung on computed tomography. Examination of the tumor revealed a focal proliferating lesion consisting of cuboidal or peg-shaped epithelial cells with slight nuclear atypia. Immunohistochemical study with anti-carcinoembryonic antigen antibody, anti-surfactant apoprotein antibody, and anti-Clara cell antibody suggested that this neoplasia has the characteristics of a type II pneumocyte. It is likely that more of these small peripheral lesions, which have potential for evolution to carcinoma, will now be encountered due to the introduction of helical CT of the chest.

Adenoma↗
PubMed1987

Histological and immunological features of primary Kaposi's sarcoma: evaluation before and after chemotherapy.

Forty-one patients with primary Kaposi's sarcoma (KS) have been evaluated clinically, histologically and immunologically at the time of diagnosis. There was no correlation between histological and immunological features. Moreover, the disease did not appear to be related to particular HLA phenotypes. The T4/T8 ratio was augmented. Leu 7+ cells were also significantly increased. The last 15 patients who received chemotherapy were recently reevaluated after treatment and an increase in B lymphocytes was observed. We also observed that spindle-shaped cells (SSC), which appear later in the histopathological course of the disease, disappear first during chemotherapy, concomitantly with the increase in B cells. We conclude that the course of the disease appears to be controlled by the host's immune response, though there is no clear correlation between histological and immunological evolution. Several immunological features differentiating it from AIDS associated KS have been found.

Aged↗
PubMed2026

Asynchronous transitions from high-risk hepatoblastoma to carcinoma.

BACKGROUND & AIMS: Most pediatric hepatocellular tumors are classified as hepatoblastoma (HB) or hepatocellular carcinoma (HCC), yet a subset exhibits mixed histological and molecular features. These hepatoblastomas with carcinoma features (HBCs) include cases provisionally designated as hepatocellular neoplasm-not otherwise specified (HCN-NOS). Their biology remains poorly understood, with unresolved questions about their cellular composition and outcomes. It is unclear whether HBCs comprise hybrid cells with combined HB and HCC characteristics (HBC cells) or admixtures of distinct HB and HCC cells. We characterized the biology, etiology, cellular composition, and evolutionary dynamics of HBCs. METHODS: We performed multi-omics profiling - including single-nucleus RNA sequencing, single-nucleus DNA sequencing, and multi-region longitudinal bulk RNA and DNA sequencing - to characterize HBC composition, evolution, and treatment response. Two-thirds of our samples were post-chemotherapy resections. RESULTS: HBCs comprise heterogeneous mixtures of HB-like, HBC-like, and HCC-like molecular cell types. Outcomes in HBC are significantly worse than in HB, and HBC cells are more chemoresistant than HB cells, with resistance shaped by their cell identity, genetic alterations, and embryonic differentiation stage. HBC cells originate from HB cells that were arrested at early hepatic stem cell development stages because of aberrant WNT signaling activation. Inhibition of WNT signaling promoted differentiation and enhanced sensitivity to chemotherapy. Furthermore, each analyzed HBC reflected a dynamic process of multiple HB-to-HBC and HBC-to-HCC transitions, underscoring their evolutionary complexity. A limitation of our study is our inability to pinpoint the role of chemotherapy-induced genome modifications. CONCLUSIONS: Multi-omics profiling of HBCs revealed key insights into their biology and composition, demonstrating that they originate from HB precursors at early hepatic stem cell development stages and that their differentiation arrest depends on sustained aberrant WNT signaling activity. IMPACT AND IMPLICATIONS: Hepatoblastomas with carcinoma features (HBCs) represent a poorly understood subset of pediatric liver tumors with mixed characteristics of hepatoblastoma (HB) and hepatocellular carcinoma (HCC). Using multi-omics profiling, we show that HBCs comprise heterogeneous mixtures of HB-like, intermediate HBC-like, and HCC-like cell populations that arise from HB precursors arrested at early hepatic stem cell developmental stages due to aberrant WNT signaling. This differentiation arrest contributes to chemoresistance and poorer clinical outcomes compared with HB. Importantly, pharmacologic inhibition of WNT signaling promoted differentiation and increased chemotherapy sensitivity, suggesting a potential therapeutic strategy. These findings refine the biological classification of HBCs and highlight differentiation-based treatment approaches for this aggressive tumor subtype.

Multiomics↗
PubMedDate not supplied

The cytogenetic basis for classifying ependymomas.

The phylogeny of ependymal cells and astrocytes can be traced to a single primitive progenitor the ependymoglia or the tanycyte, respectively. Ependymoglia cells have ependymal perikarya having astrocyte-like processes that terminate subpially in primitive glial footplates. Such cells prevail in primitive nervous systems, but they also persist regionally in the mature mammalian brain. Their fine structure has been studied in many species. An electronmicroscopic study of 8 ependymomas reveals that the neoplastic cells possess features characteristic of primitive ependymoglia; in particular they possess cell processes filled with glial filaments, terminating submesenchymally in a primitive, piston-shaped footplate. The perivascular pseudorosettes of ependymomas are the equivalents of these cell poles. The dominant phenomenon of ependymoma structure appears to be a reversion of cellular organization to the stage of primitive ependymoglia cells. On reviewing 43 ependymomas and 71 astrocytomas 11 neoplasms were found having a tissue structure reminiscent of the evolution of piloid astrocytes from ependymoglia or tanycytes, respectively. These features correspond to transitional stages seen in normal primitive brains. Tumors of this type may be characterized as a tanycytic variant of ependymomas. They appear to be relatively common in the spinal cord and present a source of confusion with piloid astrocytomas.

Adolescent↗
PubMed1980

[Epithelial invasion of the anterior chamber : exploration by scanning electron microscopy (author's transl)].

Transfixing keratoplasty was performed in a patient seven years after a lens extraction, following the appearance of corneal edema with hypertony and proliferation of a retrocorneal veil. Scanning electron microscopy examination of the posterior surface of the removed graft demonstrated the presence of a vast cellular veil formed of epithelial cells. The principal characteristics of these cells were their polygonal shape, slightly raised edges, and the presence of numerous surface microvilli. Because of the particular characteristics of this epithelium, scanning electron microscopy can be used to observe mitoses in the deep layer as well as for differentiation of the superficial layers. The epithelial cell appears to be identical, as far as its evolution is concerned, both in the aqueous humor and when in contact with the lacrymal film. When compared with other modern investigational techniques, the scanning electron microscope appears to be an effective method for studying epithelial invasion of the anterior chamber. In fact, optical microscopy is of little value in such cases, and transmitted light electron microscopy too heavy a technique for the results expected. Scanning electron microscopy enables precise definition of epithelial cells and can confirm their corneal or conjunctival origin.

Anterior Chamber↗