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At least 793 records · Page 44Linked to original sources
PubMed1999

Extrachromosomal rDNA and polarity of pro-oocytes during ovary development in Creophilus maxillosus (Coleoptera, Staphylinidae).

In telotrophic ovary of Creophilus maxillosus, the differentiation of the oocyte and nurse cells takes place within the linear clusters of sister oogonial cells. The amplification of rDNA occurs in the nuclei of pro-oocytes which are the most posterior cells of the clusters. During the consecutive oogonial divisions extrachromosomal rDNA segregates preferentially to the pro-oocyte of the next generation. We analyzed the ultrastructure of pro-oocytes and pro-nurse cells in the early and late phase of rDNA amplification in pupal ovary of Creophilus maxillosus. We found that pro-oocytes of the same generation contain variable amounts of extrachromosomal rDNA and that the presence of extra DNA is not limited to the nuclei of pro-oocytes; extra DNA is also present in the nuclei of some pro-nurse cells. Pro-oocytes can experience partial loss of extrachromosomal DNA during early oogonial divisions which is caused by the imprecise segregation of this material to the posterior pole. We believe that this imperfect segregation is a source of extrachromosomal DNA present in the nuclei of pro-nurse cells. Ultrastructural analysis showed that multiple nucleoli do not disperse in oogonial mitoses but remain associated with extrachromosomal chromatin and segregate with it to the posterior pole of the pro-oocyte. We also analyzed the ultrastructure of the germ plasm--a cytoplasmic structure present at the posterior pole of pro-oocytes. We have found that this structure contains spectrin and at the ultrastructural level is strikingly similar to the spectrosome which is present in germline cells of Drosophila. We also found spectrin in the intercellular bridges which connect oogonial cells and are known to contain fusomes.

Animals↗
PubMed2001

[Malformed macrocephalous sperm with polytails and chromosomal aberrance].

OBJECTIVE: To investigate the relationship between sperm anomalies and chromosomal aberrance and to further understand the pathological changes of anomalous spermatozoa. METHODS: Light and electronic (SEM or TEM) microscopes were used for morphological analysis. Fluorescence in situ hybridization(FISH) with chromosome X-, Y-specific probes were used for aneuploidy detection in sperms of the patient. RESULTS: Ninety eight point seven five per cent of the Papanicolaou stained sperms were observed to be abnormal; 100% of the sperm heads were abnormal, measured under oil objective (1000 times); 60.25% of the sperms had two or more tails (the maximum being eight tails). SEM and TEM demonstrated that the heads contained a large amount of cytoplasmic structure, the surfaces of heads were uneven, the nuclei were of much irregular shape; besides aberrance in quantity, anomalies occurred with centromeres, mitochondria and flagella in the tails. The results of FISH showed that the aneuploidy rate of sex chromosomes was 61.41% which was parallel to the rate of polytails. CONCLUSION: Even though the chromosomes in somatic cells are normal, the chromosomes in anomalous sperms may be abnormal.

Adult↗
PubMedDate not supplied

Expression of vimentin intermediate filament in human odontoblast.

BACKGROUND: Vimentin (57 Kda) is a cytoskeletal protein. Odontoblasts contain vimentin and it seems that this protein may function to keep the organelles and the nucleus in a definite place. However little is known about vimentin in the cytoskeleton of odontoblast processes. The purpose of the present study was, therefore to immunolocalize vimentin intermediate filament in odontoblast body and process in order to clarify the distribution of this cytoskeletal element. METHODS: 12 extracted intact premolars, from children, were used in the present study. Each specimen was decalcified in EDTA. Each tissue portion was embedded in paraffin. On sections a monoclonal anti-vimentin antibody was applied. The immunoreaction was visualized by ABC technique. RESULTS: Vimentin was expressed in the cell body and cell process of odontoblasts, however with a different immunolabeling pattern related to the topographical area of observations. In odontoblast cell bodies vimentin showed a perinuclear and cytoplasmatic staining. In the very initial portion of odontoblast process immunoreaction products for vimentin were observed in the core of the process. In the middle zone of dentin vimentin immunoreactions products also showed a granular and cross-bridge arrangements, and also, vimentin was also detected under the plasma membrane, at the periphery of the odontoblast process. Nearby the dentino-enamel junction vimentin immunolabeling was appreciated, mainly under the plasma membrane. CONCLUSIONS: On the basis of vimentin distribution in the odontoblast process it seems plausible to assume that this IF vimentin is important in forming a flexible scaffold essential for structuring cytoplasm.

Child↗
PubMed2001

Xwig1, a novel putative endoplasmic reticulum protein expressed during epithelial morphogenesis and in response to embryonic wounding.

In a subtractive differential screening, we identified a novel gene with interesting characteristics, termed Xenopus wounding induced gene 1 (Xwig1). Xwig1 encodes a novel protein of 912 amino acids containing 13 putative transmembrane segments and an evolutionarily conserved carboxy-terminal domain. Protein localization studies revealed that Xwig1 is anchored in cytoplasmic structures, presumably the endoplasmic reticulum. Expression is largely confined to epithelial cells in regions that undergo morphogenetic processes, such as blastopore closure, hindgut closure, dorsal closure and optic vesicle invagination. Interestingly, Xwig1 transcription is activated in response to embryonic epidermal wounding. The wounding-induced transcription occurs downstream of the transient phosphorylation of extracellular signal-regulated protein kinases and is in part mediated by Elk-1, but independent of dissection-induced FGF signalling. Thus, Xwig1 provides a molecular link between epithelial morphogenesis and wound healing.

Amino Acid Sequence↗
PubMed2001

Modified silver staining of nucleolar organizer regions to improve the accuracy of image analysis.

Silver staining of nucleolar organizer regions (NORs) and their subsequent quantification by image analysis are used increasingly in human pathological specimens and experimental models. Because certain conditions determined by the type of tissue and/or its fixation render AgNOR segmentation for image analysis difficult due to insufficient contrast or nonspecific silver precipitation, we propose three improvements to the original technique to overcome these difficulties. Pretreatment with 7% nitric acid produced very distinct dark brown images of AgNORs on a yellow background. The gradient of background colors allowed easy discrimination of nucleolar, nuclear and cytoplasmic structures. Seven morphometric parameters related to number, size and shape of AgNORs were evaluated quantitatively by image analysis on sections pretreated with nitric acid and on adjacent sections treated with citrate buffer in a wet autoclave according to the most widely accepted method for image analysis of AgNOR. Both methods yielded similar results. A second improvement was achieved by coating the slides with 7% celloidin solution in ethyl alcohol-ether prior to AgNOR staining and acid pretreatment. This coating prevented nonspecific silver deposition on argyrophilic bacteria and other tissue debris in human vaginal smears that could make visualizing AgNOR sites difficult. Finally, placing sections face down on the staining solution prevents the formation of nonspecific silver precipitates. These procedures can be applied together or separately according to the requirements of the material to be evaluated.

Adenocarcinoma↗
PubMed1992

Subcellular distribution and antifungal effects of fluconazole in human phagocytic cells. Demonstration of the antifungal agent in neutrophil polymorphonuclear leucocytes and monocytes by autoradiography and electron micrography.

Electron microscopic autoradiography was used to demonstrate the presence of [3H] fluconazole (CAS 86386-73-4) in neutrophils and monocytes isolated from volunteers. Quantitative analysis of the autoradiographs showed significant accumulation of fluconazole in both phagocytic cells. The distribution of fluconazole was equal in the different intracellular compartments such as cytoplasm and nucleus. Fluconazole (20 micrograms/ml) induced ultrastructural changes in Candida albicans cells which had been phagocytized by neutrophils or monocytes (macrophages) in vitro. Particularly, changes in the plasma membrane and in the cytoplasmic structure of the intraphagocytic yeast cells were observed electron microscopically.

Antifungal Agents↗
PubMed1992

Catalytic properties, tissue and intracellular distribution of neurofibromin.

The neurofibromatosis type 1 (NF1) gene encodes a protein, neurofibromin, that shows homology with members of the GTPase-activating protein (GAP) family. To study neurofibromin, rabbit polyclonal antisera were raised against two synthetic peptides. These antisera immunoprecipitated a specific protein of about 240 kDa in lysates of adult murine and rat tissues both in the soluble (S100) and to a lesser degree in the particulate (P100) fractions. The neurofibromin immunoprecipitated from the lysates of several murine organs stimulated the intrinsic GTPase activity of p21 c-Ha-ras protein. Based on immunoblotting, immunoprecipitation and GTPase assays, neurofibromin appears to be at least 10-fold more abundant in the brain than in the other murine organs. The GTPase-stimulatory activity of full-length neurofibromin, like the catalytic GAP-related domain, is inhibited by arachidonic acid and the detergent dodecyl maltoside, while phosphatidic acid, containing arachidonic and stearic acid, is non-inhibitory. Immunofluorescence analysis with anti-neurofibromin sera in NIH3T3 cells suggests that at least some of the cellular protein associates with cytoplasmic structures that are distinct from actin or tubulin filaments.

Amino Acid Sequence↗
PubMed2003

Microtubule assembly in cultured myoblasts and myotubes following nocodazole induced microtubule depolymerisation.

When myoblasts fuse into myotubes, the organisation of the cytoskeleton changes dramatically. For example, microtubules emanate in a radial array form the centrosome in myoblasts, but form linear arrays not linked to a centrosome in myotubes. It is not clear how these linear arrays are formed and nucleated. They could arise in a number of ways: by nucleation and release from centrosomal like structures, cytoplasmic assembly, breakage/severing or nucleation from non-centrosomal sites. To test which of the above mechanisms or combination of mechanisms are responsible we investigated the re-formation of microtubules after depolymerisation by nocodazole, using antibodies against pericentrin, gamma-tubulin, EB1, and tyrosinated alpha-tubulin. In myoblasts, we found that when microtubules were allowed to recover after complete depolymerisation with nocodazole, microtubule recovery began within 1 min and was complete after 5 min. Microtubules grew out from the centrosome, which was positively stained for gamma-tubulin or pericentrin. In untreated myotubes, microtubules were arranged in linear arrays, with EB1 at their ends. The pericentriolar protein, pericentrin was arranged in a band around the nucleus as well as discrete spots in the cytoplasm. In contrast, the microtubule nucleating protein gamma-tubulin was not found in a band around the nucleus, but was found in several punctuate spots throughout the cytoplasm. Further, when microtubules were allowed to recover, after complete depolymerisation with nocodazole, recovery was not as rapid as that seen in myoblasts, and we found that regrowth began with the formation of short microtubule fragments throughout the cytoplasm. Gamma-tubulin was associated with these fragments. These results suggest that in myotubes, nucleation of microtubules can be non-centrosomal.

Animals↗
PubMed2005

Autophagy--a basic mechanism and a potential role for neurodegeneration.

Autophagy constitutes a fundamental survival strategy of cells; its disturbance contributes to the pathogenesis of cancer, liver and immune disease, pathogen infection, myopathies as well as neurodegenerative disorders such as Amyotrophic lateral sclerosis, Parkinson;s, Huntington;s and Alzheimer;s disease. The pathogenesis of neurodegenerative diseases also involves a gradual and progressive loss of neuronal cells. Cells may use different pathways for active self-destruction as reflected by different morphology: while in apoptosis (or "type I") nuclear fragmentation associated with cytoplasmic condensation but preservation of organelles is predominant, autophagic degradation of the cytoplasmic structures preceding nuclear collapse is a characteristic of a second type of programmed cell death (PCD). Linking autophagy to programmed cell death initiated a controversial discussion on how a suggested role of autophagy in cell suicide might meet with its established survival function. To some extent, the diverse morphologies can be associated with distinct biochemical and molecular events [caspase-dependent and -independent death programs, DAP-kinase activity, Ras-expression, induction of autophagy genes, fate of cytoskeleton, among others]. However, there is a broad overlap between cell death pathways. Conceivably, diverse PCD programs emerged during evolution, the conservation of which allows eukaryotic cells a flexible response to physiological or pathological demands.

Animals↗
PubMed1991

Brain-specific small RNA transcript of the identifier sequences is present as a 10 S ribonucleoprotein particle.

BC-1 RNA is a small RNA transcript of the identifier repetitive sequences present in rodent genomes. The RNA has been reported to be specific to the brain and confined to the cytoplasm. The RNA level increases during the 1st month after birth. To understand its cytoplasmic function, it seems important to examine whether BC-1 RNA is present as an RNP. It is believed that the protein component may govern the functions of BC-1 RNA in the brain cells. In the present report, we have demonstrated that BC-1 RNA is not free but complexed with proteins to form a 10 S RNP in the cytoplasm. We have also shown that the 10 S RNP is not associated with cytoplasmic structures such as polysomes/ribosomes or microsomes. The buoyant density of the RNP was 1.26 g/cm3 in metrizamide. Furthermore, some of the protein components were shown to be in direct contact with RNA, since photo-cross-linking adducts of protein to BC-1 RNA were identified upon UV irradiation of the 10 S BC-1 RNP.

Animals↗
PubMed1976

[New structural components detected in B. pertussis of different serotypes].

The authors present electron microscopic data on the study of morphological peculiarities of the strains belonging to various serological types. All the strains studied had a structure characteristic of Gram-negative bacteria. Two types intracellular membranes and intracytoplasmic crystal-like structures were revealed in a number of strains (No. 222, No. gZ353, No. 475), irrespective of the serological types. Dynamics of formation of the crystal-like structures in the bacterial cell was described. Marked changes occurred in the cells with the formation of crystal-like structures: cytoplasmic membrane became detached from the cell wall with the resultant contraction of the cytoplasm; large periplastic spaces formed.

Bordetella pertussis↗
PubMedDate not supplied

[Biochemical heterogeneity of mitochondria from mucosa of rat small intestine].

Mitochondria from mucosa of rat small intestine were separated (0-11% gradient of ficoll) into fractions, differing by the content of protein, DNA and cytochrome a+a3 as well as by the respiratory activity and the activity of succinate- and NADH-dehydrogenases. Content of DNA and cytochrome a+c was shown to be increased in "heavy" mitochondrial fractions. Mitochondria od "midle" fractions possessed the highest functional activity. The data obtained suggest that the mitochondrial preparations are not contaminated by other cytoplasmic structures; they were also not impaired during isolation and fractionation. The activity of RNA and DNA synthesis in vivo and distribution of labelled mitochondrial RNA and DNA in the fractions were studied. The possible relation of mitochondrial heterogeneity to, their biogenesis is discussed.

Acid Phosphatase↗
PubMedDate not supplied

New trends in laser application: atherolysis.

Attempts to define optimal laser sources for vascular recanalization--new phenomenon--decreasing of the atherosclerotic volume under the influence of low-intensity laser beam were made. He-Ne and dye lasers (wave length: 632 nm) were used as a laser source with a mean exposure of 15 +/- 7 min. This phenomenon was established without any administration of exogenous porphyrin and was confirmed by morphological, ultrastructural and immunochemical studies. Ultrastructural investigation revealed that the action of low-intensity bares radiation on atherosclerotic plaque tissue is mediated by destruction of cells in the surface layers of the atherosclerotic arterial segments. It is noteworthy that the necrotic alterations in cells caused by laser radiation were due to primary damage of cytoplasmic structures. These observations were used in view of a new method of treating atherosclerotic lesions by transluminal laser atherolysis (TLA). Both TLA (37 patients) or laser illumination of vessels added to the conventional ball on angioplasty (25 patients) showed good patency after mechanical recanalization (9 patients). The procedure was verified by digital angiography, direct angioscopy, Doppler etc. The successful rate (82%) has proved that laser atherolysis is an effective tool in the prevention and treatment of atherosclerosis.

Adult↗
PubMed1978

[Action of vitamin D and E on the erythrocyte membrane. II. Morphological changes in the erythrocytes studied by transmission electron microscopy].

Man, rabbit, guinea-pig erythrocytes treated "in vitro" with high doses of cholecalcipherol or alpha-tocopherol release K+ and haemoglobin and show ultrastructural damages. These damages consist in a change of the red cells profile as well as in the desappearance of the glycocalix, in alterations of the membrane and of the cortical cytoplasm structure. These ultrastructural alterations are of a different degree, depending on the animal species; they partly resemble the erythrocyte changes induced by retinol. Our results are in partial agreement with the Dingle and Lucy's hypothesis on the common action of liposoluble vitamines on the erythrocyte membrane.

Animals↗
PubMedDate not supplied

[Ultrastructural and morphometric study of the myeloid parenchyma cells of mice prior and after X-ray exposure].

An electron microscopic study of initial X-ray changes in ultrastructures of bone marrow cells was performed. Such changes reached nucleous and cytoplasm organellas early (1 hour) after radiation, but were more proeminent later on. Subsequent readings (2, 6 hours) showed them more proeminent in cytoplasm structures, and the morphologic appearance was close to normal within 12, 14 days. Quantitative analyses were performed using the marrow recovery coefficient (MRC).

Animals↗
PubMed1990

Histiocytosis X of the vulva: a case report and review of the literature.

Histiocytosis X of the female genital tract is unusual. Thirty-two cases have been reported to date in the world literature. An additional case is reported herein, presenting as a vulvar ulcer in a 2.5-year-old child with osteolytic lesions of the skull, splenomegaly, and otitis media. The diagnosis of histiocytosis X may be established by identifying the Langerhans histiocyte, characterized by nuclear grooves, immunoreactivity for S-100 protein, and pentalamellar cytoplasmic structures seen by electron microscopy. Prognosis is difficult to determine with certainty. However, age of less than 2 years at presentation, multi-organ involvement, and/or organ dysfunction appear to be associated with a less favorable prognosis. The patient presented herein is currently receiving vinblastine chemotherapy for recurrence of disease, manifested as an osteolytic lesion in the skull.

Bone Diseases↗
PubMed1989

Extracellular matrix biosynthesis by cultured fetal rat lung epithelial cells. I. Characterization of the clone and the major genetic types of collagen produced.

A new cell line of fetal rat lung origin has been established using the outgrowth procedure. One clone (2G3) isolated by this procedure exhibited during early passages some of the transmission electron microscopic features (e.g., lamellar bodies) indicative of type II pneumocytes and was selected for further study. This cell line has a stable modal chromosome number of 44 and has not been found to develop tumors in athymic rodents. The clone exhibits a biphasic growth curve with an initial generation time of approximately 22 hours at 37 degrees C. The cultures are not contact inhibited but rather develop an organized secondary growth pattern. Initially after subculture, a monolayer is formed consisting of cells which exhibit a cobblestone appearance. After development of this monolayer, a secondary growth pattern emerges. This latter phase of growth is characterized by spindle-shaped cells displaying a pattern of organization that delimits lumina on top of the initial monolayer. At the ultrastructural level, desmosomes are observed, and concurrent with the development of the secondary growth pattern, there is the appearance of dense cytoplasmic structures which resemble lamellar bodies. Based upon the origin, growth properties, and morphologic features of the cells, this clone has been designated fetal rat lung epithelial (FRLE) cells. The collagens secreted into the culture medium and present in the cell layers of FRLE cell cultures, which have developed the secondary growth pattern, were isolated using limited pepsin digestion and differential salt fractionation. Polyacrylamide gel electrophoresis under denaturing conditions indicated that FRLE cells synthesized components corresponding to the chains present in types I, III, IV, and V collagen molecules with no major differences occurring between the profiles of cell-associated and secreted molecules. Carboxymethyl-trisacryl chromatographic analysis revealed that approximately 80% of the collagen synthesized was type I and that approximately 20% of this genetic type of collagen was recovered as the type I homotrimer. Types III, IV, and V molecules accounted for 16, 2, and 3%, respectively, of the total collagen synthesized. Additionally, the type V collagen synthesized by FRLE cells was found to have the molecular compositions alpha 1(V) alpha 2(V) alpha 3(V) and [alpha 1(V)]3. These observations suggest that the collagen biosynthetic profile of the fetal or immature type II cell may differ from that of the fully differentiated type II pneumocyte. Furthermore, it is proposed that cultured FRLE cells may be a useful in vitro model system for investigating the regulation of macromolecular synthesis in and the differentiation and maturation of the fetal alveolar epithelial cell.

Animals↗
PubMed1988

Ultrastructure of myeloma cells in patients with common acute lymphoblastic leukemia antigen (CALLA)-positive myeloma.

We investigated the ultrastructure of myeloma cells obtained from four cases of common acute lymphoblastic leukemia antigen (CALLA)-positive myeloma. Clinically, the disease was aggressive and our patients died with a median survival after diagnosis of only 62 days. By light microscopic criteria of Greipp et al., their disease was classified as plasmablastic, immature (two cases), and intermediate. In contrast, the myeloma cells of all four cases were judged to be immature and abnormal on the basis of the electron microscopic observation. Characteristic features were sparse heterochromatin, high to moderate nucleocytoplasmic ratio, nuclear bodies, thin and short rough endoplasmic reticula, scattered pattern of mitochondria, and polysomes consisting of five to six ribosomes, along with irregular nuclear membrane, poorly developed organella, and abnormalities in cytoplasmic structures such as dense bodies, vacuoli, buddings, single-sac loop-like structures, multilamellar bodies, and abnormal inclusion bodies. While overlapping each other, it is suggested that the CALLA-positive and the plasmablastic myelomas should be classified separately. Thus, the electron microscopic study, like the immunological marker analysis, provides a useful means for better assessment regarding immaturity and abnormality of myeloma cells.

Adult↗