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PubMed1972

Division of protoplasmic astrocytes in acute experimental hepatic encephalopathy. An electron microscopic study.

The ultrastructural features of dividing protoplasmic astrocytes, induced by the production of hepatic encephalopathy, are described. True cellular hyperplasia, as manifested by cytokinesis at the site of paired nuclei, was demonstrated. The cytoplasm contained structural elements suggesting that cell division occurs by a highly organized process. Some of the observations were similar to those found in mitotic division in other types of cells, raising the possibility that cell division in protoplasmic astrocytosis might occur by mitosis rather than by amitosis, as widely held.

Acute Disease↗
PubMed1977

Nerve-muscle interaction: changes in the cellular organization of a skeletal muscle upon denervation.

The alterations in the organization of lumbrical muscle of the rat have been investigated following denervation, with emphasis on the structure of cytoplasmic constituents, sarcolemma in the synaptic and non-synaptic regions and acetylcholinesterase activity. The appearance of 15--18 nm intramenbranous particles in the non-synaptic sarcolemma is thought to be related to the known acetylcholine extrajunctional sensitivity which is manifested after denervation. The acetylcholinesterase activity is greatly reduced in the synaptic region in the denervated muscle. These changes are discussed in relation to the known physiological and biochemical data.

Acetylcholinesterase↗
PubMed1984

Comparative studies of local anesthetic effects on artificial membranes and isolated cardiac tissues.

Drugs with local anesthetic properties like propranolol, tetracaine, lidocaine, procaine, induce concentration dependent potentials in artificial membranes. The size of the drug induced potential correlates with cardiodepressant activity, measured as decrease in force of contraction of guinea-pig atria and papillary muscles. Drugs inducing high potentials like propranolol and tetracaine, show low EC50 values in cardiac tissues. Propranolol in comparison to lidocaine diffuses more rapidly across the lipid membrane as derived from the time dependent decline in membrane potential and from radioactive tracer measurements. After application of a single drug concentration on cardiac tissues a longer time is required for propranolol to reach steady state than for example for lidocaine. Effects are higher at pH 9 than at pH 7 and 7.4, respectively. The results suggest that the site of action of propranolol primarily are cytoplasmic cell structures whereas that of lidocaine and procaine is the outer membrane surface.

Anesthetics, Local↗
PubMed1982

On the cultivation of Trypanosoma cruzi in tissue cultures of the spinal and sympathetic ganglion from the chick embryo.

Trypanosoma cruzi was cultured in spinal and sympathetic ganglion cells of chick embryos. The "Y" and the "CL" strains were used for comparison, showing no differences in their tropism for the different cell types of the ganglion cultures. Nerve cells as well as satellite and Schwann cells served as host for the parasite's intracellular cycle. No toxic effect on the nerve cells was observed in heavily infected cultures. The destruction of the nerve cells is due to the multiplication of the parasites in the cell's cytoplasm. Its structure in the non parasitized nerve cells, even in direct contact with parasites, looks normal under the optical microscope and also shows no alteration in its ultrastructure.

Animals↗
PubMed1983

[Ultrastructural observations on human endometrial stromal cells during the normal menstrual cycle--with special reference to so-called "predecidual cells"].

Human endometrial stromal cells during the normal menstrual cycle were observed with the transmission electron microscope, the scanning electron microscope and the freeze-fracture replica method. In the early proliferative phase, the stromal cells had the characteristics of mesenchymal cells but in the early secretory phase, they resembled fibroblasts. In the late secretory phase, the stromal cells (so called "predecidual cells") were characterized by their large size, rounded shape, and their abundant cytoplasms with well-developed organelles. Furthermore, "predecidual cells" also had the following conspicuous features: 1. In the cytoplasms numerous membrane-bounded collagen fibers were seen, and positive acid-phosphatase activity was detected in these fibers. 2. Neighbouring "predecidual cells" were often joined to each other by "gap junctions". 3. "Predecidual cells" had many "coated regions" on their cytoplasmic membranes. Structural changes in endometrial stromal cells were discussed in regard to the function of these cells.

Alkaline Phosphatase↗
PubMed1983

Vascular changes in nerves in experimental leprosy--an ultrastructural study.

Ultrastructural observations made on the blood vessels of nerves in CBA/J mice with experimentally produced M. leprae infection revealed cytoplasmic filamentous structures along with large sized vacuoles in the endothelial cells and reduplication of peripericytal basement membranes in the 6-9 months of infection. In animals with late infection of 9-15 months duration, the endothelial cells presented foamy appearance caused by an increase in the number of vacuoles. These findings are suggestive of degenerative changes in the endothelial cells probably due to circulation of noxious substance in the blood stream.

Animals↗
PubMedDate not supplied

[Regulation of nitrogenase activity and biosynthesis in Clostridium butyricum].

The effect of various factors on the activity and biosynthesis of nitrogenase in Clostridium butyricum was estimated by the rate of acetylene reduction at different growth phases in the static culture. The activity of nitrogenase was found to be low in vegetative cells; it increased and reached the maximum at the stage of prospore formation and decreased in the course of sporulation. The duration of different stages in the cell growth cycle depended on temperature and the composition of the medium. An increase in the rate of nitrogenase synthesis at the stage of prospore formation was favoured by the presence of sodium acetate or yeast autolysate in the medium; ammonium chloride inhibited the mechanism of nitrogenase biosynthesis. Cytoplasmic membranous structures such as tubular-vesicular or lamellar mesosomes were formed in active nitrogen fixing cells grown in a medium with yeast autolysat. Such structures were absent from cells with a low activity grown in a medium containing ammonium chloride.

Clostridium↗
PubMed1982

Chemical phototoxicity in humans.

Phototoxic reactions may be induced by endogenous or exogenous chemicals. Endogenous photosensitizers made by the body include porphyrin molecules which are responsible for the photocutaneous syndromes noted in the porphyrias. Exogenous photosensitizers may arrive on the skin through topical applications or may be distributed through the vasculature. Topical photosensitizers are found in cosmetics, medications, plants, and industrial and air pollutant emissions. Systemic photosensitizers consist primarily of therapeutic agents. Acute and chronic phototoxic reactions may occur. The acute response is generally characterized by erythema and edema followed by hyperpigmentation and desquamation. The end point of chronic damage may be cutaneous cancer formation. The mechanisms of these changes may well relate to nucleic acid injury, protein and membrane damage, and alterations in other nuclear and cytoplasmic molecular structures. However, translation of experimental information into human responses remains to be clarified. A great deal of investigation is still needed in developing assays for detecting phototoxic chemicals and for defining mechanisms involved in phototoxic events in human skin.

Drug-Related Side Effects and Adverse Reactions↗
PubMed1981

Cellular localization of the molecular forms of acetylcholinesterase in rat pheochromocytoma PC12 cells treated with nerve growth factor.

In rat pheochromocytoma (PC12) cells treated with nerve growth factor (NGF), there are several molecular forms of the enzyme acetylcholinesterase (AChE) which sediment on sucrose density gradients at 4 to 6, 10, and 16 S, respectively. We have investigated the cellular localization of these forms in PC12 cells. In order to determine which forms are soluble and which are membrane bound, we extracted PC12 cells in buffers of various ionic strengths and detergent compositions. To distinguish internal from external forms of the enzyme, we examined the effect of di-isopropyl fluorophosphate and BW284c51 dibromide, membrane-permeable and -impermeable inhibitors of AChE, respectively, AChE forms in intact cells. We also determined the susceptibility of the forms in intact cells to collagenase treatment. Based on these studies, we conclude that the globular G1 and G2 (4 to 6 S) forms are internal and consist of both soluble and membrane-associated species. Thirty percent of the G4 (10 S) form is bound to cytoplasmic membrane structures, while the remainder occurs as an integral component of the plasma membrane. The asymmetric A12 (16 S) form is also a surface protein but is extracted by high salt without detergent and is released from intact cells by collagenase. This form thus contains a collagenous domain and is located outside of the plasma membrane, where it may be associated with an extracellular matrix.

Acetylcholinesterase↗
PubMed1993

[Cytokeratins as markers of differentiation. Expression profiles in epithelia and epithelial tumors].

Intermediate filaments (IFs; diameter, about 10 nm) are cytoplasmic cytoskeletal structures found in most vertebrate cells. Their protein subunits comprise a large multi-gene family of related proteins, which make it possible to divide IFs into seven separate classes whose expression is cell-type-dependent. The most important IF classes are cytokeratin (CK) filaments (epithelial cells), vimentin filaments (mesenchymal cells), desmin filaments (muscle cells), glial filaments (astrocytes), and neurofilaments (nerve cells). As the specificity of expression of IF proteins is retained in malignant tumors, they are suitable as histological markers of differentiation (tumor markers). The protein subunits of the epithelial CK filaments are unusually diverse, and within the various types of epithelia, their expression is differentiation specific. Until recently, the catalog of human CKs comprised 19 related, yet distinct polypeptides (CKs 1-19; Moll et al., 1982a); CK 20 can now be added to this list. On the basis of sequence relationships, two CK subfamilies can be delineated (CKs 9-20 = type I; CKs 1-8 = type II). Any given epithelial cell exhibits a characteristic, differentiation-dependent combination of two or more CK polypeptides, with type-I and -II polypeptides always occurring in stoichiometric amounts (i.e., as "pairs"), because the basic structural unit of the CK filaments is a heterotypical tetramer complex. On the basis of their main tissue distribution patterns, it is possible further to subdivide these polypeptides into CKs typical of stratified squamous epithelia (CKs 1-6, 9-17) and those typical of simple columnar epithelia (CKs 7, 8, 18-20); these CKs exhibit differential expression patterns in the various types of squamous and columnar epithelia. The actual characterization of the novel CK 20 as a CK initially proved to be rather difficult, as this cytoskeletal protein, which can be biochemically isolated from cells of the intestinal epithelium (M(r) 46,000; previously called "IT protein"), exhibits no reaction with numerous well-known CK antibodies in Western blots. However, a series of other characteristics typical of CKs could be demonstrated. Thus, IT protein was found, in vitro (nitrocellulose-blot binding test, native gel electrophoresis), to for heterotypical complexes with the type-II CK 8, and these complexes were able to reconstitute themselves into typical IFs in vitro. Chymotrypsin-cleaving experiments revealed the presence of a resistant core fragment (M(r) 38,000), indicating a alpha-helical "coiled-coil" conformation typical of IFs.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

A novel approach to the microdosimetry of neutron capture therapy. Part I. High-resolution quantitative autoradiography applied to microdosimetry in neutron capture therapy.

A novel approach to the microdosimetry of neutron capture therapy has been developed using high-resolution quantitative autoradiography (HRQAR) and two-dimensional Monte Carlo simulation. This approach has been applied using actual cell morphology (nuclear and cytoplasmic cell structures) and the measured microdistribution of boron-10 in a transplanted murine brain tumor (GL261) containing p-boronophenylalanine (BPA) as the boron compound. The 2D Monte Carlo transport code for the alpha and 7Li charged particles from the 10B(n,alpha)7Li reactions has been developed as a surrogate to a full 3D approach to calculate a variety of different microdosimetric parameters. The HRQAR method and the surrogate 2D Monte Carlo approach are described in detail and examples of their use are presented.

Animals↗
PubMed1995

Effects of various antineoplastic agents on an established human melanoma cell line (G-361).

An established human melanoma cell line was treated with several concentrations of three antineoplastic drugs: melphalan (0.016, 0.032, 0.16 microns), CCNU (1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea) (0.04, 0.21, 0.42 microM), and 4-OHA (4-hydroxyanisole) (4.01 x 10(-4), 1.20 x 10(-3), 2.4 x 10(-3) microM), and the effects on cell growth and viability were compared. 24 hours after treatment, 4-OHA (ID50 = 2.4 x 10(-3) microM) was more cytotoxic than melphalan (ID50 = 0.016 microM) and CCNU (ID50 = 0.21 microM). However, after 96 hours exposure, the most effective drug was CCNU (growth rate = -1.277), which caused the death of the culture. This was followed by melphalan (growth rate = -1.024) and finally 4-OHA (growth rate = -0.69). Similar ultrastructural cell injuries were observed after the use of the three drugs: the dilation of endoplasmic reticulum vesicles and the nuclear membrane; mitochondria swelling; and the existence of lamellar structures and cytoplasmic vacuoles.

Anisoles↗
PubMed1995

Hypergastrinemia and gastric enterochromaffin-like cells.

The enterochromaffin-like (ECL) cell of the oxyntic, acid-secreting mucosa is at present the most extensively studied endocrine cell type in the gastrointestinal tract. It is functionally related to acid secretion through paracrine release of histamine. Its ability to undergo proliferation in response to the trophic stimulus of hypergastrinemia has important implications in pathology, being involved in the development of ECL-cell carcinoid tumors of rodents treated with powerful inhibitors of acid secretion as well as in that of most human gastric carcinoids which, with rare exceptions, are composed of ECL cells. The various aspects of the ECL-cell response to hypergastrinemia in humans are discussed in this review. The trophic effect of gastrin is specific for ECL cells and its sensitivity is enhanced by the female sex and by the genetic background of the multiple endocrine neoplasia type 1 (MEN-1) syndrome. Exposure of ECL cells to hypergastrinemia induces peculiar changes in the structure of cytoplasmic granules and triggers the phenotypic expression of a novel protein, the alpha subunit of glycoprotein hormones, absent in normal cells. The ECL-cell hyperplasia driven by hypergastrinemia may influence the hypersecretory gastric state of patients with Zollinger-Ellison syndrome (ZES) by inappropriate intramucosal secretion of histamine and may contribute to the high circulating levels of basic fibroblast growth factor (bFGF), an ECL-cell product responsible for parathyroid mitogenic effects in MEN-1 patients. However, hypergastrinemia per se cannot promote evolution of hyperplasia into carcinoid tumors, for which additional unknown factors, particularly associated with atrophic gastritis or MEN-1 syndrome, are required. ECL-cell carcinoids developing within these backgrounds have a strikingly more favorable course than their gastrin-independent counterpart. Suppression of hypergastrinemia, either by antrectomy or treatment with somatostatin analogues, may induce regression of both ECL-cell hyperplasia and gastrin-sensitive ECL-cell carcinoids.

Carcinoid Tumor↗
PubMed1976

Lupus nephritis: correlation between light, electron microscopic and immunofluorescent findings and renal function.

Percutaneous renal biopsies from 56 patients with systemic lupus erythematosus were studied to determine the relationship between renal function and the light microscopic, electron microscopic and immunofluorescent antibody findings. The glomerular lesions were classified into 5 major groups: diffuse membranoproliferative glomerulonephritis (34%), diffuse proliferative glomerulonephritis (26.8%), membranous nephropathy (12.5%), minimal lesion ('nil') and minimal lesion with increased mesangial matrix and/or cells (21.4%) and focal and segmental glomerulonephritis (5.3%). Minimal lesions and focal and segmental glomerulonephritis were invariably associated with normal renal function. Patients with moderate to severe renal involvement and the nephrotic syndrome had predominantly diffuse membranoproliferative and diffuse proliferative glomerulonephritis. Membranous nephropathy was associated with moderate renal involvement and the nephrotic syndrome in 50% of cases. Patients with pure mesangial electron dense deposits had normal renal function or mild renal involvement when the deposits were heavy. Moderate and heavy subepithelial, and intramembranous/subepithelial deposits were associated with moderate to severe renal involvement and the nephrotic syndrome. Renal involvement was most severe with heavy subendothelial deposits. Cytoplasmic tubuloreticular structures measuring approximately 18 to 20 nm in diameter and 80 to 100 nm in length were found in 93% of all biopsies, but bore no relationship to the renal function of the patients. Anti-Hu-IgG fluorescent deposits were found in all the renal biopsies; in 81.3% these were associated with less heavily stained deposits of immunoglobulin IgA, IgD and IgM. Early complement components Clq and C4 were utilized in the complement pathway of activation. Pure mesangial fluorescent deposits were associated with normal renal function or mild proteinuria. Diffuse granular and lumpy deposits along the capillary loops were usually associated with moderate to severe renal involvement and the nephrotic syndrome. In the present series of cases, there was a good correlation between renal function of patients with systemic lupus erythematosus and the glomerular lesions as determined by light, electron microscopic and immunofluorescent microscopic findings.

Adolescent↗
PubMed1993

[Changes in the cortical astrocytes of the progeny from the moderate alcoholization of female rats].

It has been shown that in the sensomotor cortex of the offspring of female rats moderately alcoholized during of before pregnancy there are three categories of astrocyte changes: signs of delayed of maturation of some astrocytes, dystrophic and reparative changes. The dystrophic changes include abnormal structures in cytoplasm, edema of mitochondria, damage to the vesicular component of the Golgi apparatus. These changes are more distinct earlier stages of the postnatal ontogenesis. Later the signs of reparative processes are more significant, but the dystrophic astrocyte changes still remain. Changes in cortical astrocytes of the experimental offspring reflect the damage to the neuron-glia-capillary system.

Aging↗
PubMed1993

Ultrastructural observations on Weibel-Palade bodies suggesting exocytosis.

Weibel-Palade bodies were studied in endothelium in human tumours by transmission electron microscopy of ultrathin sections. In addition to individual Weibel-Palade bodies lying in the cytoplasm, one structure was observed which was interpreted as a Weibel-Palade body and in which the limiting membrane was in continuity with the plasmalemma, suggesting exocytosis. The interior of non-exocytosing Weibel-Palade bodies was generally rather dense and the microtubular inclusions well delineated. Some, however, were of reduced density and had fewer and less well delineated microtubular elements. This appearance corresponded with that of the putatively exocytosing Weibel-Palade body. It was suggested that the microtubular elements re-organise and possibly disorganise with the approach of endocytosis.

Endothelium, Vascular↗
PubMedDate not supplied

[The biotype and genetic characteristics of an isolate of the cowpox virus causing infection in a child].

A virus, identified as cowpox virus by its biological properties and the results of the analysis of its DNA, was isolated from a sick 4-year-old child with a clinical picture of pox, though having had no contacts with known natural carriers of the causative agent of this infection. At the same time the isolated virus was found to differ from the reference strain, as well as from other isolates of vaccinia virus by some biological markers (and in particular by the structure of cytoplasmic inclusions of type A) and by the restriction profile of DNA. The Hind III maps indicating the location of restriction sites made it possible to localize the genome differences established in this study. The specific feature of this case was the previous close contact of the child with a mole which was probably the source of infection.

Animals↗