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Biomedical subjects

A Radu

Publications and source records attributed to A Radu.

At least 37 records · Page 2Linked to original sources
PubMed1994

The human CAN protein, a putative oncogene product associated with myeloid leukemogenesis, is a nuclear pore complex protein that faces the cytoplasm.

We have carried out partial amino acid sequence analysis of a putative nuclear pore complex protein (nucleoporin) of rat that reacts with wheat germ agglutinin and with the polyspecific monoclonal antibody 414. Surprisingly, these partial amino acid sequence data revealed a high degree of similarity with the human CAN protein, the complete cDNA-derived primary structure of which was reported by Von Lindern et al. [Von Lindern, M., Fornerod, M., van Baal, S., Jaegle, M., de Wit, T., Buijs, A. & Grosveld, G. (1992) Mol. Cell. Biol. 12, 1687-1697]. The CAN protein has been proposed to be a putative oncogene product associated with myeloid leukemogenesis. Its subcellular localization was not established. To confirm that the putative rat nucleoporin is indeed a homolog of the human CAN protein and to determine its subcellular localization, we expressed a 39-kDa internal segment of the 213,790-Da human CAN protein in Escherichia coli and raised monospecific antibodies, which reacted with the putative rat nucleoporin. Immunofluorescence microscopy of HeLa cells gave a punctate nuclear surface staining pattern characteristic of nucleoporins, and immunoelectron microscopy yielded specific decoration of the cytoplasmic side of the nuclear pore complex. This suggests that the protein is part of the short fibers that emanate from the cytoplasmic aspect of the nuclear pore complex. In agreement with previously proposed nomenclature for nucleoporins, we propose the alternative term nup214 (nucleoporin of 214 kDa) for the CAN protein.

Amino Acid Sequence↗
PubMed1993

Nup155 is a novel nuclear pore complex protein that contains neither repetitive sequence motifs nor reacts with WGA.

We have molecularly cloned and sequenced a rat liver nuclear pore complex (NPC) protein of calculated molecular mass of 155 kD. Consistent with recently proposed nomenclature this protein is termed nucleoporin 155, or nup155. Unlike other nups that have so far been molecularly cloned and sequenced, nup155 does not contain repetitive sequence domains. It does not show similarity to the sequences of other proteins, including any nups, so far compiled in the data bases. Like other vertebrate nups which have been characterized nup155 possesses abundant (46 in total) consensus sites for various kinases. By immunoelectron microscopy, nup155 is associated with both the nucleoplasmic and the cytoplasmic aspect of the NPC and is therefore possibly a component of the symmetrically arranged NPC substructures. In mitotic cells, nup155 assumes a diffuse cytoplasmic distribution. Nup155 is among the integral of 30 proteins that were extracted from rat liver nuclear envelopes by 2.0 M urea/1.0 mM EDTA, separated from WGA-reactive proteins by WGA-Sepharose and further subfractionated by SDS-hydroxylapatite. These proteins are potential candidates for being nups.

3T3 Cells↗
PubMed1993

Autologous melanoma vaccine induces inflammatory responses in melanoma metastases: relevance to immunologic regression and immunotherapy.

Human primary malignant melanoma is often accompanied by a host response of infiltrating lymphocytes suggestive of tumor antigen-induced immunity and correlated in some tumors with prognosis. Whereas metastatic melanoma deposits typically are not inflamed and contain relatively few lymphocytes and dendritic immune cells, immunization with autologous melanoma-cell vaccine may induce a clinical inflammatory response associated with mononuclear-cell infiltration. In this study, we characterize immune responses to dermal and subcutaneous melanoma metastases in dinitrophenyl (DNP)-pre-sensitized patients immunized with DNP-conjugated melanoma cells. Patients so treated develop cutaneous delayed hypersensitivity responses to DNP-conjugated autologous mononuclear cells, and approximately one-half show clinical evidence of inflammation and regression of metastases within 2-4 months. Whereas pre-vaccination biopsies of metastatic melanoma failed to reveal significant infiltration by lymphocytes, biopsies obtained after vaccination and coincident with clinical inflammation were markedly infiltrated preponderantly by T cells with a CD8+ phenotype. Clustering of these cells about individual degenerating melanoma cells in a manner analogous to "satellitosis" was a consistent feature of this reaction. Enhanced expression of intercellular adhesion molecule-1 (ICAM-1) and human leukocyte antigen (HLA)-DR by melanoma cells were invariably associated with zones of T-cell infiltration, whereas diminished or absent expression was observed in relatively unaffected regions of tumors. Numerous HLA-DR+, CD4+, CD1-, Leu-1- dendritic cells were also associated with zones of early T-cell infiltration. These data indicate that clinical inflammation and regression of metastatic melanoma induced by autologous melanoma-cell vaccine involves activated T cells with cytotoxic-suppressor phenotype and dendritic cells putatively capable of local antigen presentation. ICAM-1 upregulation on melanoma cells is a likely mediator of ligand interaction between infiltrating T cells and target cells in this model of antigen-induced host anti-tumor response. Structural alterations identified in this setting (e.g., tumor cell satellitosis) may provide additional insight into identifying features of naturally occurring host immune responses to primary cutaneous melanomas.

Dermatitis, Atopic↗
PubMed1991

4-Hydroxynonenal reduces junctional communication between endothelial cells in culture.

The effect of 4-hydroxynonenal (HNE), a lipid peroxidation product, on junctional communication (JC) among cultured vascular endothelial cells was assessed by both study of the transfer of microinjected 6-carboxyfluorescein between neighboring cells and measurement by a "cut-loading and dye transfer" technique. Both methods indicated that at concentrations higher than 10(-9) M and testing times between 6 and 8 h HNE reduces endothelial cell junctional communication. At 10(-8) M, a gradual development of HNE effect appears during 6-8 h of exposure but is followed by a slow recovery completed at 20 h. The reduction in junctional communication is not produced by the inhibition of protein synthesis, as tested by radiolabeled leucine incorporation. The HNE effect might be relevant to pathological processes in which lipid peroxidation is associated with uncontrolled cell proliferation, as in atherogenesis and promotion of carcinogenesis by chronic inflammation.

Aldehydes↗
PubMed1991

A simple polymerase chain reaction apparatus based on a computer printer.

We describe a very simple laboratory-made polymerase chain reaction (PCR) apparatus. The reaction tubes are placed in a holder fixed through a mechanical arm to the tape cartridge of a computer printer. A computer controls the horizontal movement of the tube carrier by sending the proper printing commands. The holder is raised or lowered by a frame fixed to the paper-advancing roller of the printer. The system allows the programmed movement of the test tubes within the holder, successively through three thermal baths placed in front of the printer. DNA from single lambda gtll lysis plaques was successfully amplified with this system in our laboratory.

Animals↗
PubMed1988

Calf cardiac valvular endothelial cells in culture: production of glycosaminoglycans, prostacyclin and fibronectin.

To study the roles played by cardiac valvular endothelium in normal and pathologic conditions, we have established and characterized a system of bovine valvular endothelial cells (VEC) in culture. Viable VEC from calf atrioventricular valves were obtained by a non-enzymatic procedure using 3 mM ethylenediamine-tetraacetic acid (EDTA) as dissociating agent. The cells grown in Dulbecco's modified Eagle's medium supplemented with non-essential amino acids, vitamins and 20% fetal calf serum, developed as monolayers of closely apposed polygonal cells which were subcultured for up to seven passages. VEC maintained in culture the general ultrastructure displayed in vivo, expressed von Willebrand factor, presented angiotensin converting enzyme activity and synthesized a rich extracellular matrix. VEC preserved the cell surface anionic sites (detected with cationized ferritin, pI 8.4) and cationic sites (visualized with haemeundecapeptide pI 4.85), and took up, especially by adsorptive endocytosis, albumin-gold conjugate. The cells were coupled by functional communicating (gap) junctions, as demonstrated by microinjection of 6-carboxyfluorescein. VEC in culture produced fibronectin, prostacyclin, hyaluronic acid and heparin-like glycosaminoglycans (identified by electrophoresis, enzyme digestion, and deaminative cleavage of molecules). These properties render cultured VEC a suitable model for investigating their functions and involvement in normal and pathologic heart valves.

Animals↗
PubMed1987

The hyperlipidemic hamster as a model of experimental atherosclerosis.

Male hamsters were fed a hyperlipidemic diet consisting of standard chow supplemented with 3% cholesterol and 15% commercial butter for 12 months. In about 3 weeks serum total cholesterol doubled, raised 4-fold after the 4th week and after 10 months attained a 17-fold value. Low density lipoproteins (LDL)-cholesterol increased 4-fold after 4 weeks and about 13-fold after 10 months compared to control animals. In the first 2 weeks mononuclear cells began to adhere to the endothelium and a very intense stromal reaction appeared in the intima of the aortic arch. At the end of the 4th week of diet, Oil Red O stainable deposits were visible on the thoracic aorta, mostly on the arch, some of them as isolated, lipid-laden cells and others distributed on focal areas. Smooth muscle cells (SMC) appeared also in the intima of hyperlipidemic hamsters, compared to normal animals which had no macrophages or smooth muscle cells in the intima of the aortic specimens examined. Up to 6 months, smooth muscle cells in the intima and media began to load with lipids, as well as endothelial cells. After 10 months the affected zones looked like human atherosclerotic plaque with huge cholesterol crystal deposits, calcium deposits and necrosis. The endothelium, though very thinned and loaded with lipids, was morphologically intact.

Animals↗
PubMed1987

Cellular events in the development of valvular atherosclerotic lesions induced by experimental hypercholesterolemia.

The onset and evolution of ultrastructural changes in the cardiac valves induced by a cholesterol-rich diet were investigated in rabbit and hamster. In both animal models, the atrioventricular and sigmoid valves were comparably affected by lesions intermediary between fatty streak and fibrous plaque. The earliest detectable modification was the progressive accumulation in the subendothelium of extracellular liposome-like structures rich in unesterified cholesterol, associated with the proliferation of a basal lamina-like material. This was followed by the diapedesis of blood monocytes in the same location, which became macrophages increasingly loaded with lipid deposits. Resident interstitial cells accumulate lipids, as well. In advanced stages, the macrophage-derived foam cells clustered, deforming the valve leaflets. The resident macrophages accumulated lipids later and more slowly, while partly preserving their ultrastructure. The advanced lesions are characterized by marked stromal proliferation, massive intra- and extracellular deposition of lipids and cholesterol crystals and the appearance of a necrotic core. The salient findings of these studies were: (1) the appearance of extracellular liposomes as the earliest event in atherogenesis; (2) the capability of the valvular interstitial cells to accumulate lipids; and (3) the slow response of resident macrophages to the cholesterol-rich diet. The results revealed that hypercholesterolemia produces in the cardiac valves atherosclerotic lesions of an intermediate type, which can deform the leaflets thus altering their normal function.

Animals↗
PubMed1986

Interstitial cells of the heart valves possess characteristics similar to smooth muscle cells.

Interstitial cells of heart atrioventricular and sigmoid valves were examined in several laboratory animals (rabbit, hamster, rat, and mouse) and in humans. These cells constitute a large fraction of the total cell population of the valve; in mouse atrioventricular valves, they amount to approximately 30% of the volumetric density. By their ultrastructural features and functional properties, valvular interstitial cells are intermediate between fibroblasts and vascular smooth muscle cells. Like fibroblasts, valvular interstitial cells lack a basal lamina establishing direct and extensive contacts with collagen fibers, elastin microfibrils, and proteoglycans of the matrix. The cells have numerous slender and long processes, connected to one another, forming a complex cellular framework spanning the entire valve. Similar to smooth muscle cells, valvular interstitial cells are extensively coupled by communicating junctions as shown by thin sections, freeze-fracture, lanthanum staining, and carboxyfluorescein microinjection. The cells contain numerous bundles of actin filaments, which are decorated by the S1 fragment of heavy meromyosin. Valvular interstitial cells also express cyclic guanosine-monophosphate-dependent protein kinase, as detected by immunofluorescence and immunoperoxidase histochemistry. Motor nerve endings are located closely apposed to valvular interstitial cells: structurally most of them appear to be of the adrenergic type. Valvular interstitial cells contract on epinephrine or angiotensin II stimulation as shown both in culture and in situ (valvular strips). Taken together these observations suggest that VIC may have contractile properties, which can account for a controlled tonus, actively correlated with the cyclically changing forces acting on valves during diastole and systole.

Actin Cytoskeleton↗
PubMed1982

Hormonal regulation of cell junction permeability: upregulation by catecholamine and prostaglandin E1.

By cellular activation with hormones, we test the proposition (Loewenstein, W.R., Physiol. Rev. 61:829, 1981) that the permeability of cell junction is upregulated through elevation of the level of cyclic AMP. Cultured rat glioma C-6 cells, with beta-adrenergic receptors, and human lung WI-38 cells, with prostaglandin receptors, were exposed to catecholamine (isoproterenol) and prostaglandin E1, respectively, while their junctions were probed with microinjected fluorescent-labelled mono-, di-, and triglutamate. Junctional permeability, as indexed by the proportion of cell interfaces transferring the probes, rose after the hormones treatments. The increase in permeability took several hours to develop and was associated with an increase in the number of gap-junctional membrane with an increase in the number of gap-junctional membrane particles (freeze-fracture electron microscopy). Such interaction between hormonal and junctional intercellular communication may provide a mechanism for physiological regulation of junctional communication and (perhaps as part of that) for physiological coordination of responses of cells in organ and tissues to hormones.

Alprostadil↗
PubMed1977

Focal abnormalities in mitochondrial distribution in muscle. Two atypical cases of so-called "central core disease".

Describing two new cases of so-called Central Core Disease, the authors revealed certain atypical features: The cores were formed in central as well as in peripheral position; they were observed in some apparently type II fibers; typical "structured" and "unstructured" cores coexisted with "reversed" core. Starting from this pictures a cycle of core formation was imaginated supposing to be initiated as the consequence of abnormal functional interrelationship between muscular and neural components in early myogenesis.

Adult↗
PubMed1977

Myotubular (centronuclear) (neuro-)myopathy. I. Clinical, genetical and morphological studies.

Five new cases of myotubular (centronuclear) (neuro-)myopathy are presented. Myometric studies revealed type I fibre atrophy and mispositioned nuclei, at various stages between the myotubular structure and the normal subsarcolemmic position. Certain morphological changes, for instance target structures, suggest denervation involving the fibres in an early stage of myogenesis; differentiation seems to be more affected than growth. The genetic defect has an autosomal recessive mode of inheritance with penetrance and degree of expressivity varying from one case to another in the three families.

Adult↗
PubMed1975

Duchenne muscular dystrophy and poliomyelitis. A study of dystrophic-denervated muscle.

A systematic study of dystrophy-denervation in human muscle showed minimal morphometabolic differences between dystrophic and dystrophic-denervated muscle. The only certain conclusion is that denervation influences the rhythm of evolution of the dystrophy without impressing any of the few characteristics considered at present as peculiar to denervation.

Child↗