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At least 1,189 records · Page 66Linked to original sources
PubMed1990

[Morphological changes and sperm decapitation as a cause of fertility disorders in breeding stock].

Decapitation of spermatozoa was recorded in a young boar as a consequence of epididymitis and in a young dog (mastiff) and a young bull (Brown Swiss breed) as a congenital cause of the subfertility and sterility of the affected animal. Decapitation of spermatozoa as a consequence of an inflammation led to the sterility of the breeding male and affected 52 to 68% of the spermatozoa. The motility of the spermatozoa was reduced considerably (10 to 20%) and the flagella were not observed to move without the heads. In cases of congenital decapitation of spermatozoa, sperm motility in the dog and bull was reduced, but the flagella were observed to move without the heads. Decapitation affected 15 to 42% of the spermatozoa and most frequently it was accompanied by a narrowing of head base and by the presence of a protoplasmic drop, located proximally. Further developmental changes, affecting the flagella of the sperms, were observed in the dog. The mentioned morphological changes led to infertility in the dog and to a substantial reduction of fertility in the bull. After natural mating of the bull with a superovulated cow, the ten eggs obtained included four blastocysts, two were degenerated, and four were unfertilized.

Animals↗
PubMed1990

[Studies of human skin by cryofractographic and electron-microscopic methods].

Ultrathin slices from the human abdominal skin and platinum-carbonic replicas, obtained by means of the freeze-fracture method have been studied electron microscopically. Transmembranous proteins are revealed on the membrane surface as membrane-bound particles with the diameter 5-7 nm. They mainly concentrate on the membrane protoplasmic surface. Certain difference is noted in distribution of tonofibrils in cytoplasm of the epidermal cells, when various methods for preparation of specimens to be investigated are used. Predominance of the freeze-fracture method comparing to the routine method of electron microscopy is discussed, since the specimens do not subjected to fixation, dehydration and resin saturation.

Cell Membrane↗
PubMed1990

Mitosis and protein synthesis. 3. Organelle relocation during normal and colcemid-arrested M-phase in HeLa S-3 cells.

During M-phase, most organelles in HeLa S-3 cells are relocated in the 'cortex' or outer-zone of cytoplasm. Elements of the rough endoplasmic reticulum (rER) and polysome assemblies persist to varying degrees from cell to cell in this zone. Dilatation of rER cisternae becomes prominent in a small percentage of metaphases, and its occurrence and significance is discussed. Remnants of the Golgi apparatus are almost invariably peripheralized. Its cisternal elements are lost in early mitosis, and reappear in late telophase. The inner zone of the protoplasm around the chromosomes loses its associated intermediate filaments and excludes organelles until cytokinesis commences. A rapid repopulation occurs by mid-telophase. The same pattern of zoning is found in cells entering mitosis in the presence of colcemid, but is followed by some repopulation of the inner zone by a small minority of organelles after approximately 2 h of arrest. Centrioles are particularly prone to becoming enmeshed within the 'ball' of entangled c-metaphase chromosomes. An unusually high degree of pairing of cytoplasmic membranes, probably rER elements, also occurs in colcemid-arrested metaphases, which may further contribute to their reduced level of protein synthesis. These have been referred to as 'confronting cisternae' (Ghadially, 1988). The zoning of the cytoplasm may result from nuclear envelope breakdown during mitosis, and is not specifically related to or associated with microtubule redeployment during spindle formation in M-phase. Differences in the extent of zoning in other cell lines are discussed in comparison with HeLa S-3 cells.

Anaphase↗
PubMed1986

The ultrastructural localization of tri-n-butyltin in human erythrocyte membranes during shape transformation leading to hemolysis.

Scanning electron microscopy, transmission electron microscopy, freeze-fracture, and x-ray energy dispersive spectrometry were used to localize tri-n-butyltin (TBT) in human erythrocytes (RBC's). TBT induced a rapid shape transformation of the RBC discocyte to an echinocyte, which led to hemolysis at concentrations at or above 10 microM TBT. Electron dense spheres or ellipsoids were observed in association with blood cell membranes at or above 10 microM TBT. These structures were visualized initially in thin sections when postfixed with osmium tetroxide. Control cell preparations without TBT did not exhibit these structural densities when fixed with osmium. Freeze-fracture replicas confirmed the presence of TBT aggregates associated with cell membranes as intercalations in the lipid bilayer. In thin sections, these structures measured 71.5 +/- 18.2 nm in diameter. In freeze-fracture replicas of TBT-treated RBC's, particulate structures measuring 60 +/- 18.5 nm in diameter were present on membrane exoplasmic fracture faces and 59.6 +/- 10.8-nm depressions on membrane protoplasmic fracture faces. Qualitative x-ray energy dispersive spectrometry analysis of ultrathin sections of glutaraldehyde-carbohydrazide-embedded samples revealed that the membrane-associated aggregates contained tin. TBT-treated RBC's that were washed with normal saline resulted in a paucity of TBT aggregates associated with the membranes and a reduction in the RBC hemolysis rate. RBC shape transformation occurred at each concentration examined from 0.1 to 100 microM TBT, but was reversible below 1 microM TBT.

Electron Probe Microanalysis↗
PubMed1989

[O-specific L-hapten in the composition of Shigella sonnei].

Along with classical lipopolysaccharide (LPS), O-specific material not precipitated by ultracentrifugation has been isolated from the water-phenol extract of S. sonnei avirulent strain 9090 possessing complete antigenic properties. The purification of O-antigen contained in the supernatant fluid has been carried out by the gel filtration of the fluid, previously treated with ribonuclease, in a column packed with Sephadex G-100. The polysaccharide nature of O-antigen thus obtained, the absence of lipid A and KDO and the low content of hexoses, or core-specific saccharides of S. sonnei LPS, in this antigen make it possible to classify this material with O-components of microbial cells, described by different authors as "native protoplasmic polysaccharide" or "L-hapten" and formed by polymers of LPS O-side chains. The content of this component in S. sonnei strains under study is, on the average, 2.5% of the weight of dry microbial substance. L-hapten preparations obtained in the course of our investigations have been found to contain two O-specific antigens detected by immunoelectrophoresis and immunodiffusion, as well as by sedimentation in saccharose gradient, where they form peaks corresponding to 4.3 S and 10.8 S. This polysaccharide O-antigen is supposed to be capable of interaction with ribosomal particles and suitable for use as a component of ribosomal dysentery vaccines.

Antigens, Bacterial↗
PubMed1989

Localization of barriers to water flow in toad urinary bladder.

Although it is well accepted that vasopressin (ADH) increases the permeability to water of the toad bladder granular cell's luminal membrane, recent studies have suggested that regulation also takes place at an additional "postluminal" site within the epithelial granular cell. These studies are based upon the observation that a number of experimental maneuvers can alter tissue permeability to water, but do not change the number of particle aggregates observed on the protoplasmic face of the granular cell's luminal membrane with freeze-fracture electron microscopy. These aggregates are believed by many investigators to mediate the transport of water across the luminal membrane. The dissociation between permeability and aggregate frequency described above has been variously interpreted as the consequence of changes in the permeability of the aggregates themselves, or of changes in the permeability of a "postluminal" barrier that is functionally in series with the luminal membrane. We attempted to distinguish between these 2 possibilities by studying paired toad bladders during 3 protocols that alter vasopressin-stimulated water flow across the intact tissue without altering aggregate frequency. Estimates of the permeability of postluminal barriers were obtained by exposing the luminal surface to amphotericin B, an antibiotic that forms water-permeant channels in the luminal membrane. Of the 3 protocols, only diminishing bladder filling volume decreased the water flow elicited by luminal amphotericin B, suggesting that only that protocol indeed decreased the permeability of some postluminal barrier. The other 2 protocols, increasing PCO2 and repeatedly stimulating the bladder with vasopressin, did not alter amphotericin B-elicited flow, suggesting that postluminal barriers were not altered by these 2 protocols.(ABSTRACT TRUNCATED AT 250 WORDS)

Amphotericin B↗
PubMed1989

Comparison of dot immunobinding assay, enzyme-linked immunosorbent assay and immunodiffusion for serodiagnosis of paratuberculosis.

A rapid, simple and inexpensive dot immunobinding assay (DIA) was evaluated for the serodiagnosis of paratuberculosis in cattle. The assay was performed on nitrocellulose strips which were dotted with purified protoplasmic antigen of Mycobacterium paratuberculosis. After incubation with test serum samples, the bound antibodies were detected using an enzyme-amplified immunostaining procedure. The efficacy of DIA as a screening test for paratuberculosis was compared to that of an enzyme-linked immunosorbent assay (ELISA), a modified agar gel immunodiffusion (mAGID) test, and an AGID test using 329 serum samples from cattle which were examined for M. paratuberculosis infection by a sensitive fecal culture technique. The DIA and ELISA had comparable results and both of the enzyme immunoassays had higher sensitivity than tests based on AGID. The sensitivity of all four tests was influenced by the intensity of fecal bacterial shedding. Preabsorption of sera with Mycobacterium phlei increased the sensitivity of both enzyme immunoassays. the specificity but reduced the sensitivity of both enzyme immunoassays.

Animals↗
PubMed1985

Structure of axon terminals and active zones at synapses on lizard twitch and tonic muscle fibers.

The freeze-fracture technique was used to study differences in membrane structure which could explain differences in the number of quanta released from axon terminals on twitch and tonic muscle fibers in Anolis intercostal muscles. The protoplasmic leaflets of axon terminals facing lizard twitch muscle fibers have intramembrane particle specializations characterized by two parallel linear particle arrays each composed of two particle rows which lie perpendicular to the axis of shallow ridges in the axolemma. During K+ depolarization, vesicles open between the arrays, confirming that these structures are the active zones for synaptic vesicle opening. Active zones at axon terminals on tonic fibers are defined by one linear particle array composed of two parallel particle rows oriented along the axis of a shallow presynaptic ridge; vesicles open beside these arrays. Thus, there are more particles near active zone vesicles in terminals on twitch fibers. Even though terminals on twitch and tonic muscle fibers seem to have similar numbers of synaptic vesicles associated with their active zones, a presynaptic action potential is reported to release at least 10 times more quanta from terminals on twitch fibers. We postulate that the differences in quantal output are related to the observed differences in the number of active zone particles flanking synaptic vesicles at the active zone. Indeed, the correlation between the distribution of these particles and the level of transmitter release provides additional support for the idea that they are the calcium channels which couple transmitter release to the action potential.

Animals↗
PubMedDate not supplied

[Descriptions and comparative changes of modifications on ultrastructure of cocci and bacteridium of saliva under "in vitro" influence of sparse and dense solutions of chlorhexidine di-gluconate].

In our investigation we have studied and analysed the modifications on the ultrastructure of the cocci and bacteridium of saliva under "in vitro" influence of sparse and dense solutions chlorhexidine di-gluconate. We noticed that the sparse solutions of the drug revealed ruptures of the cellular wall and of the cellular membrane as well as "plasmoptysis" and "plasmolysis". The protoplasm, showing a general coagulation, damage of the cytoplasmic membrane and the cellular wall and in concentrations of 1% and 2% we observed a disorganisation of the nuclear chromatin.

Bacteria↗
PubMedDate not supplied

Cerebrospinal fluid cytomorphology identification of benign cells originating in the central nervous system.

The chief cellular consituents of CSF are the "free cells" of the pia-arachnoid, ependyma, and choroid. These cells are of diverse types, but have their mesenchymal origin in common. Usually they offer no difficulty in identification since they are predominantly histiocytic. However, these "free cells" may be morphologically changed in reaction to an appropriate stimulus, and may therefore be a source of error in diagnostic material. Cells having mesothelial characteristics are not found in the CSF compartment and therefore the term pia-arachnoid mesothelial cells appears inappropriate. The only neuroectodermal derivative that was easily identifiable was the choroidal cell. It is distinctive and unequivocal. We were unable to recognize ependymal cells in our present study. Glial cells (protoplasmic and fibrous astrocytes) and neurons can be recognized when neural tissue is penetrated in the process of collecting CSF.

Animals↗
PubMed1978

Intramembranous particles in erythrocyte, reticulocyte and erythroblastic leukemic cells of the rat: a model system for erythrocyte maturation.

The density and size distribution of intramembranous particles (IMP) were determined for cells of the erythroid series. The number and size of IMP were measured on both fracture faces of erythroblastic leukemia cells, phenylhydrazine-induced reticulocytes and mature erythrocytes. We found that the number of IMP adhering to the protoplasmic fracture face of the plasma membrane increased with increasing maturation, while the number of particles adhering to the external fracture face did not correlate with maturational stage. In general, the mean size of particles adhering to both fracture faces decreased with increasing maturation after the erythroblastic stage. We interpret these results to mean that the IMP seen are derived from more than one macromolecular species and that they are distributed asymmetrically in the plasma membrane.

Animals↗
PubMed1989

[Morphology of glial cells in the lower olivary complex of the pigeon (Columba livia). I. Astrocytes].

The morphologic peculiarities of astrocytes in the lower olivary complex (LOC of a pigeon were examined at light and electron microscopic level. Usage of histological technique established the presence of three varieties: fibrous, real protoplasmic and covered type of astrocytes. In LOC of a pigeon most of astrocytes, observed by the electron microscope, possessed in their cytoplasm bunches of filaments, which passed and proceeded along side to astrocytic arborizations parallelly. Other type of arborizations were the so-called astrocytic plates, which were frequently arranged at layers and embraced the elements of the neuropappila under the form of capsules. Multiple desmosomo-like and gap junctions were encountered between adjoining astrocytic membranes. Heterogenous astro-oligodendrocytic gap junctions were observed as well. The functional significance of these glial cells and their probable role in neuronal metabolism is discussed on the basis of a comparative analysis of the structural and ultrastructural characteristics of astrocytes in LOC of a pigeon and in various species of mammals.

Animals↗
PubMed1987

[Ultrastructure of brain tumor].

Ultrastructure of 15 brain tumors (6 astrocytomas, 5 meningiomas, 2 medulloblastomas and 2 Schwannomas) was observed by transmission electron microscope. In astrocytoma, both the fibrous and protoplasmic astrocytes were found. There were abundant capillaries among the tumor cells. The glia limitans outside the base membrane of certain capillaries were destroyed to different degrees. It indicates that the blood brain barrier may be damaged. Ultrastructurally, medulloblastoma cells may be divided into types I and II. The former was poorly differentiated but the latter was differentiated differently. Meningioma was similar to Schwannoma with complex cell membrane projections. The former had a lot of round mitochondria and filaments in the projections, between which desmosomes were observed. Schwannoma had the typical collagenous fibers among the projections. As to the epithelioid ultrastructure of meningioma, the authors speculate that the majority of meningiomas originate from the mesothelial cells of the arachnoid granulations.

Astrocytoma↗
PubMed1987

[Paraneoplastic limbic encephalopathy, inappropriate ADH secretion and recurrent subclinical epileptic seizures. Clinical, anatomo-pathological and metabolic correlations by positron emission tomography].

We report a case of limbic encephalopathy clinically characterized by a progressive amnestic syndrome and many EEG seizures mainly localized on the left temporal area. Biological investigations revealed diabetes mellitus and a syndrome of inappropriate antidiuretic hormone secretion (IADH). Haemodynamic and metabolic studies by positron-emission tomography showed an important increase in cerebral blood flow (CBF) and cerebral metabolic rate of oxygen on the left anterior temporal region precisely where the electrical seizures were recorded. Nine months later, severe disorders of memory and a dramatic decrease in CBF and CMRO2 on the same area region were present. At autopsy, a small size oat cell bronchial carcinoma was found with metastases in two small adjacent lymph nodes. Neuropathological examination showed atrophy (neuronal loss, protoplasmic gliosis) in the amygdala; where there was in addition an area of nodular gliosis. The hippocampus and parahippocampal gyrus lesions were severe on the left and moderate on the right side. The authors discuss the nosology of their case in the paraneoplastic syndromes and, with a review of the literature, the role of ADH and cellular hyperactivity in the pathogenesis of specifically localized neuronal alterations.

Amnesia↗
PubMed1985

Multiple marker analysis in the avian optic tectum reveals three classes of neuroglia and carbonic anhydrase-containing neurons.

The distribution and biochemical diversity of neuroglial cells in the avian optic tectum were analyzed using immunohistochemical techniques. Polyclonal and monoclonal antibodies were employed to define the distributions and localizations of four proteins that are considered to be glial-specific in the mammalian central nervous system: glutamine synthetase, carbonic anhydrase-C, glial fibrillary acidic protein, and S-100 protein. The results showed the presence of at least three distinguishable populations of glia: glutamine synthetase/glial fibrillary acidic protein-positive fibrous astrocytes, glutamine synthetase/carbonic anhydrase-C-positive protoplasmic astrocytes, and S-100-positive oligodendroglia. In addition, a distinct population of neurons was observed that showed very intense immunostaining for the presence of carbonic anhydrase-C. The results suggest that the segregation of biochemical functions in the major categories of brain neuroglial cells (oligodendroglia and astroglia) varies significantly between vertebrate species. This observation raises the possibility of using comparative studies to refine our understanding of the roles that glial cells play in nervous tissue.

Animals↗
PubMed1986

Freeze-fracture studies on the surface membranes of pleomorphic bloodstream and in vitro transformed procyclic Trypanosoma brucei.

The surface membranes of bloodstream long slender, short stumpy and culture procyclic stages of Trypanosoma brucei brucei were compared with respect to freeze-fracture electron microscopy, intramembrane particle (IMP) distribution and beta-hydroxysterol content as shown by the characteristic intramembrane lesions induced by the polyene antibiotic, filipin. Little difference was observed between IMP density of long slender and short stumpy form body membranes: IMP's were more abundant on the protoplasmic face (PF) than on the exoplasmic face (EF). The procyclic culture form body membrane showed an increased density of PF IMPs and a decreased density of EF IMPs over their bloodstream short stumpy form predecessors. Flagellar membrane fracture faces displayed higher IMP densities than body membrane fracture faces of the same trypanosome. The numbers of filipin-induced lesions (FIL) indicated an increased level of beta-hydroxysterols in the short stumpy forms relative to the level in the long slender bloodforms. FIL density was further increased in the body membrane of the procyclic culture form. FIL density was higher in the flagellar membrane than in the corresponding body membrane and FIL were excluded from flagellum to body attachment zones of the flagellar membrane of all stages. The polarity of the FIL in the surface membranes was reversed on transforming from bloodstream to culture procyclic stages. These observations indicate qualitative differences between the surface membranes of the three stages, independent of the presence or absence of the surface coat.

Animals↗
PubMed1989

Perturbation of the sarcolemmal membrane in isoproterenol-induced myocardial injury of the rat. Permeability and freeze-fracture studies in vivo and in vitro.

The mechanism whereby cardiotoxic doses of isoproterenol (ISO) induces early permeability alteration of the sarcolemmal membrane is unknown; both beta-receptor overstimulation and direct toxic effect of ISO oxidation products have been implicated. There has been no morphologic observation, furthermore, on the structural basis of permeability alteration during this process. The purpose of the present study was to compare the morphology of cardiocyte injury induced by ISO and oxidized ISO (ISO-O2) and to visualize perturbation of the sarcolemma correlating with the leaky membrane. The authors studied the left ventricular myocardium of rats 10 and 60 minutes after subcutaneous administration of 85 mg/kg ISO and isolated perfused rat hearts exposed for 10 minutes either to ISO or ISO-O2 in a dose of 100 mg/l (10(-4) M) to determine the permeability of the sarcolemmal membrane using the extracellular diffusion tracer horseradish peroxidase (HRP) by light and thin section electron microscopy, the morphology of the sarcolemmal membrane by means of freeze-fracture electron microscopy, and the density of intramembrane particles (IMP) in the sarcolemmal membrane by planimetry using freeze-fracture electron microscopy. In in vivo rat hearts both 10 and 60 minutes after ISO and in vitro (isolated perfused) rat hearts exposed to either ISO or ISO-O2 for 10 minutes, HRP labeled the sarcoplasm of focally located cardiocytes implicating leakiness of the sarcolemmal membrane. HRP positive cardiocytes (with the exception of the in vivo 10 minute group) showed characteristic features of contraction band necrosis (both on light and thin-section electron microscopy) in all groups. Freeze-fracture electron microscopy of sarcolemmal protoplasmic (P) membrane faces revealed two populations of cardiocytes in all groups. P-membrane faces in one population of cardiocytes appeared as in the control. In the other population of cardiocytes, P-membrane faces showed irregular tears. Planimetry demonstrated a significant decrease of IMP numerical densities in P-membrane faces with tears in the in vivo 10 minute group and both with or without tears in the in vivo 60 minutes group and the in vitro groups compared with the control values. Furthermore, with the exception of the 10 minute in vivo group, IMP densities significantly decreased in sarcolemmal membranes with tears compared with those without tears in all experimental groups. These observations are consistent with the view that catecholamine induced myocardial injury is, at least partly, related to the direct toxic effect of catecholamine oxidation products on the sarcolemmal membrane.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗