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At least 1,477 records · Page 82Linked to original sources
PubMed1987

Stromal luteoma of the ovary: a clinicopathological analysis of 25 cases.

The clinical and pathological features of 25 stromal luteomas were reviewed. The patients ranged in age from 28-74 (average 58.4) years. The most common initial manifestation (60%) was abnormal vaginal bleeding; three patients (12%) were virilized. The tumors, only one of which was bilateral, ranged from 0.25-2.9 (average 1.3) cm in greatest diameter. They were all well circumscribed. Microscopic examination revealed unencapsulated nodules composed of rounded polyhedral cells that were arranged either diffusely or in nests and cords. Twenty percent showed degeneration within aggregates of cell resulting in the formation of pseudoacinar structures. The cytoplasm of the neoplastic cells was generally eosinophilic and granular, and lipochrome granules were present in over half the tumors. In 92% of the cases hyperthecosis was present in the adjacent ovarian stroma. Follow-up of 6 months to 17 years was available for 19 patients. Sixteen of them were alive and free of disease; the remaining three died of other causes. The benign course in all the cases in which follow-up data were available was expected in view of the small size of the tumors and their benign microscopic appearance.

Adult↗
PubMed2006

The clear cell variant of solid pseudopapillary tumor of the pancreas: a previously unrecognized pancreatic neoplasm.

Solid pseudopapillary tumor is a rare but distinctive pancreatic neoplasm whose cell phenotype remains a mystery. We report 3 cases of a previously undescribed variant of solid pseudopapillary tumor of the pancreas composed almost entirely of multivacuolated clear cells (>90%). The cytoplasmic vacuoles did not contain glycogen, mucin, or lipid but seemed to be formed by dilatation of the endoplasmic reticulum and mitochondria. The tumors displayed prominent trabeculae and a solid growth pattern but lacked the characteristic pseudopapillary pattern of the classical solid pseudopapillary tumor. In contrast, the clinical features, gross characteristics, and immunoprofile were similar to those of classical solid pseudopapillary tumor. Two of the patients were young adult females with well-demarcated tumors involving the body and tail of the pancreas. Tumor cells showed immunoreactivity for vimentin, CD10, CD56, synaptophysin, and nuclear accumulation of beta catenin. In 2 patients, 1 male and 1 female, the tumors were discovered incidentally. Despite vascular invasion in one of the tumors all 3 patients are disease free after distal pancreatectomy. Clues to distinguish the clear cell variant of solid pseudopapillary tumor from endocrine pancreatic tumor composed of clear cells, clear and foamy cell variants of ductal carcinoma, metastatic renal cell carcinoma, serous cystadenoma and ectopic adrenocortical nodules are provided.

Adenocarcinoma, Clear Cell↗
PubMed2002

Characterization of a human immunodeficiency virus type 1 pre-integration complex in which the majority of the cDNA is resistant to DNase I digestion.

The human immunodeficiency virus type 1 (HIV-1) pre-integration complex (PIC) is a cytoplasmic nucleoprotein structure derived from the core of the virion and is responsible for reverse transcription of viral RNA to cDNA, transport to the nucleus and integration of the cDNA into the genome of the infected target cell. Others have shown by Mu phage-mediated PCR footprinting that only the LTRs of the cDNA of PICs isolated early in infection are protected by bound protein, while the rest of the genome is susceptible to nuclease attack. Here, using DNase I footprinting, we confirmed that the majority of the cDNA of PICs isolated at 8.5 h after infection with cell-free virus was sensitive to digestion with DNase I and that only part of the LTRs (approximately 6% of the total cDNA) was protected. However, PICs isolated 90 min later (at 10 h post-infection) were very different in that the majority (approximately 90%) of cDNA was protected from nuclease degradation. These late PICs were integration active in vitro. We conclude that HIV-1 has at least two types of PIC, an early PIC characterized by protein bound only at the LTRs, and a late, and possibly more mature form, in which protein is bound along the length of the cDNA.

Cell Nucleus↗
PubMed2003

Dengue virus type 2 NS3 protease and NS2B-NS3 protease precursor induce apoptosis.

Apoptosis was detected in Vero cell cultures expressing transfected dengue virus type 2 (DENV-2) genes. Approximately 17.5 and 51.5 % of cells expressing NS3 serine protease and NS2B-NS3(185) serine protease precursor protein [NS2B-NS3(185)(pro)] genes, respectively, were apoptotic. The percentage of apoptotic cells was significantly higher in cell cultures expressing NS2B-NS3(185)(pro). NS2B-NS3(185)(pro) was detected as NS2B-NS3(185)(pro)-EGFP fusion protein in cytoplasmic vesicular structures in the apoptotic cells. Site-directed mutagenesis which replaced His(51) with Ala within the protease catalytic triad significantly reduced the ability of the expressed NS3 and NS2B-NS3(185)(pro) to induce apoptosis. Results from the present study showed that DENV-2-encoded NS3 serine protease induces apoptosis, which is enhanced in cells expressing its precursor, NS2B-NS3(185)(pro). These findings suggest the importance of NS2B as a cofactor to NS3 protease-induced apoptosis.

Amino Acid Sequence↗
PubMed2006

Human papillomaviruses target the double-stranded RNA protein kinase pathway.

The double-stranded RNA protein kinase (PKR) pathway plays a vital role in the innate immune response to viral infection. Activation of PKR following virus entry can lead to a shutdown in translation, thereby inhibiting viral protein synthesis and replication. Little is currently known about whether human papillomaviruses (HPVs) modulate PKR expression and activity. In this study, normal human foreskin keratinocytes (NHKs) transfected stably with the HPV 31 or 16 genomes and cell lines expressing the HPV 16 E6 and E7 oncoproteins were used to examine effects on the PKR pathway. HPV gene products were found to modulate PKR phosphorylation, activity and localization. The levels of total PKR protein were reduced modestly in cells that maintained HPV 16 or 31 episomes through a reduction in PKR transcription. However, levels of phosphorylated PKR were decreased 4-fold through a post-transcriptional mechanism mediated by E6 and E7 that was independent of the transcriptional downregulation mediated by HPV. In response to infection by vesicular stomatitis virus, phosphorylation of eIF2alpha was blocked in cells expressing HPV oncoproteins, but not in NHKs. Finally, it was observed that the cellular localization of PKR was altered by HPV gene products in HPV raft cultures, as well as HPV-positive patient biopsies. This effect was mediated by the HPV E6 oncoprotein and leads to the co-localization of PKR with P-bodies. These studies demonstrate that high-risk HPVs target the PKR pathway by multiple mechanisms.

Animals↗
PubMed1986

Ultrastructural Changes in Potato Tuber Pith Cells during Brown Center Development.

Electron microscopy revealed that subjecting ;Russet Burbank' potato (Solanum tuberosum L.) plants to 2 days of cool temperature growing conditions (18 degrees C days/10 degrees C nights) did not produce visible damage or changes in tuber pith tissue when compared to warm-grown tubers (23 degrees C days/18 degrees C nights). However, damage to some tuber pith cells was observed after 5 days of cool treatment. Eight days of cool treatment produced extensive alterations in cell structure. The cytoplasm of the cool-treated tuber pith cells had become highly vesiculated and there was evidence of complete destruction of amyloplast membranes and tonoplasts. In many cases the starch grains appeared to be undergoing hydrolysis suggesting total disruption of normal cell function. Sixteen days of cool treatment were sufficient to produce visible brown center development in all cool-grown tubers examined. Electron microscopy of these tissues revealed that, although some organelles were still present, the cytoplasm had become extremely vesiculated and lacked any resemblance to that of tissue from warm-grown tubers. Gross, irregular thickening of cell walls was also detected.

Journal Article↗
PubMed1998

Stoichiometric shifts in the common bean mitochondrial genome leading to male sterility and spontaneous reversion to fertility

The plant mitochondrial genome is characterized by a complex, multipartite structure. In cytoplasmic male-sterile (CMS) common bean, the sterility-inducing mitochondrial configuration maps as three autonomous DNA molecules, one containing the sterility-associated sequence pvs-or f 239. We constructed a physical map of the mitochondrial genome from the direct progenitors to the CMS cytoplasm and have shown that it maps as a single, circular master configuration. With long-exposure autoradiography of DNA gel blots and polymerase chain reaction analysis, we demonstrate that the three-molecule CMS-associated configuration was present at unusually low copy number within the progenitor genome and that the progenitor form was present substoichiometrically within the genome of the CMS line. Furthermore, upon spontaneous reversion to fertility, the progenitor genomic configuration as well as the molecule containing the pvs-or f 239 sterility-associated sequence were both maintained at substoichiometric levels within the revertant genome. In vitro mitochondrial incubation results demonstrated that the genomic shift of the pvs-or f 239-containing molecule to substoichiometric levels upon spontaneous reversion was a reversible phenomenon. Moreover, we demonstrate that substoichiometric forms, apparently silent with regard to gene expression, are transcriptionally and translationally active once amplified. Thus, copy number suppression may serve as an effective means of regulating gene expression in plant mitochondria.

Journal Article↗
PubMed1991

Inflammatory properties of neutrophil-activating protein-1/interleukin 8 (NAP-1/IL-8) in human skin: a light- and electronmicroscopic study.

Neutrophil-activating protein-1/interleukin 8 (NAP-1/IL-8), purified to homogeneity from lipopolysaccharide-stimulated human peripheral blood monocytes, was injected intracutaneously into human skin. Sequential biopsy specimens were taken in order to investigate the sequence of ultrastructural changes induced by the cytokine. Whereas intracutaneous injection of 100 ng of NAP-1/IL-8 per site caused no macroscopic changes, by histology infiltration with polymorphonuclear leukocytes (PMN) and monocytes was present within 1 h and increased at 3 and 5 h. No lymphocyte infiltration was noted. The first ultrastructural changes (30 min) consisted of the presence of cytoplasmic 7-nm microfilament bundles, as well as numerous protrusions of the luminal plasma membrane of endothelial cells (EC). As a striking feature, multiple 100- to 160-nm electron lucent vesicles could be observed in the EC cytoplasm. These structures differed from plasmalemmal vesicles and suggest secretory activity. When PMN and monocytes appeared in the vascular lumen (1 h and later), the number of 100-160-nm electron-lucent vesicles had decreased significantly. In contrast to C5a-injected skin sites, mast cell degranulation was absent.

Complement C5a↗
PubMed1981

Changes in surface protein structure of bull spermatozoa during epididymal maturation.

The surface proteins of bull spermatozoa from caput and cauda epididymis were labelled by lactoperoxidase-catalyzed radioiodination and solubilized and analyzed by SDS-PAG-electrophoresis. The surface protein patterns of caput and cauda epididymal spermatozoa resembled each other but some distinct differences could be found. Caput epididymal spermatozoa revealed a protein peak with molecular weight of 15 000 - 18 000 daltons but this peak was not found on cauda epididymal spermatozoa. On caput epididymal spermatozoa the most intensely labelled protein peak was located between 90 000 and 100 000 daltons but on cauda epididymal spermatozoa the corresponding peak was only weakly labelled and had a molecular weight of 80 000 - 90 000 daltons. Surface protein with molecular weight of 42 000 - 47 000 daltons was dominating on cauda epididymal spermatozoa. The surface protein structure of cytoplasmic droplets did not drastically differ from that of epididymal spermatozoa.

Animals↗
PubMed1983

Residual glomerular lesions in postpartal women with toxemia of pregnancy.

Renal biopsies from 10 patients who had residual symptoms of toxemia of pregnancy were examined by light, electron and immunofluorescent microscopy. The biopsies were performed 1 month to 3 months postpartum. The glomeruli showed a similar lesion, even though to a lesser degree, to that found in toxemia of pregnancy. Subepithelial swellings and endothelial cytoplasmic microtubular structures were also observed. Mesangial and monocyte-like cells contained lysosomes, cholesterol clefts and lipid-containing vacuoles with or without myelin figures, suggesting reparative process in the glomeruli. The present study indicates that the glomerular injury persists for a few months after delivery, together with the concurrent reparative process.

Adult↗
PubMed1979

Rhabdospora thelohani Laguessé, 1895 (Apicomplexa): new host and geographic records with taxonomic considerations.

New fish species and geographic records for Rhabdospora thelohani Laguessé, 1895 (rodlet cells) are presented. Additionally, the ultrastructure of R. thelohani in Alburnoides bipunctatus ohridanus Karaman, Borostomias antarcticus (Lönnberg), Leuciscus cephalus albus Bonaparte and Rutilus rubilio (Bonaparte) is compared with that reported by other authors and with members of Subphylum Apicomplexa. The ultrastructure of R. thelohani was similar in all the fish species examined; however, the organism was not present in all members of any single species and had intertissue density variations. Rhabdospora thelohani is pyriform, averaging in size 7 X 12 micrometer, with a basal nucleus. The surface complex is composed of a layer (0.5 micrometer diameter) formed by microfilaments (9.3 nm) and an outer trilaminar membrane (9.3 nm). The cytoplasm contains structures identical to rhoptries, micronemes and subpellicular microtubules. Mitochondria, Golgi apparatus, and rough endoplasmic reticulum were not observed, althouth free ribosomes were present and arranged in a vesicular pattern. The observations suggest that the organism moves between cell of epithelial layers and is either released into a lumen intact or passively or actively discharges its contents into a lumen. Results from this study indicate that R. thelohani should be considered a member of Apicomplexa unless definitive evidence is presented to the contrary.

Animals↗
PubMed1975

Langerhans cells in actinic reticuloid.

Actinic reticuloid was observed in a patient following the development of porphyria cutanea tarda. A cutaneous lymphoma-like infiltrate was found histologically and at the ultrastructural level. In the infiltrate, the main population was histiocytic, with some mast cells and mononuclear cells. Most of the histiocytic cells contained numerous typical Langerhans granules and worm-like structures. Crystalloid cytoplasmic inclusions were occasionally detected.

Adult↗
PubMed1988

Ultrastructural changes produced in Ehrlich ascites carcinoma cells by ultraviolet-visible radiation in the presence of melanins.

Irradiation of Ehrlich ascites carcinoma (EAC) cells in the presence of pheomelanin, i.e., red hair melanin (RHM), has been reported to produce extensive cell lysis. Irradiation in the presence of eumelanin, i.e., black hair melanin (BHM), or irradiation in the absence of either type of melanin did not produce this effect. We observed that RHM particles penetrated the cell membrane without apparent structural damage to the cell or the cell membrane. Irradiation of the cells in the absence of melanin did not produce any changes in the ultrastructure of the cells. Incubation of the cells in the dark in the presence of RHM produced only minor structural, mainly cytoplasmic changes. Irradiation of the cells in the presence of RHM produced extensive ultrastructural changes prior to complete cell lysis; these changes were more severe than the effects of incubation of the cells in the dark in the presence of RHM. When the cells incubated in the dark or irradiated in the presence of latex particles or either one of the eumelanins particles, viz. BHM or synthetic dopa melanin, these particles did not penetrate into the cells or produce any ultrastructural changes. These particles were in fact not even ingested by the cells.

Animals↗
PubMed1985

Regulation of luminal membrane water permeability by water flow in toad urinary bladder.

Intramembranous particle aggregates (presumed sites for water flow) which appear in the luminal membrane consequent to ADH treatment are derived from cytoplasmic membrane structures (now termed "aggrephores") which fuse with the luminal membrane. We have previously shown that bladders stimulated in the absence of an osmotic gradient have about twice as many aggregates and about three times as many sites of aggrephore fusion as bladders stimulated with ADH in the presence of a 175 milliosmolal gradient. The present studies show that the frequency of fused aggrephores and luminal membrane aggregates can be modified as a consequence of alterations in transmembrane water flow initiated by changing the transbladder osmotic gradient during hormone stimulation. Bladders treated with ADH for 1 hr without a gradient and then for 1 hr with a gradient had approximately 1/3 as many aggregates and fusion sites as paired bladders treated for 2 hr without a gradient. Conversely, bladders treated with ADH for 1 hr with a gradient and then for 1 hr without a gradient had approximately 2x as many aggregates and fusion sites as bladders treated for 2 hr with a gradient. In other experiments we demonstrate that the time course of hormone washout is greatly accelerated if carried out in the presence of an osmotic gradient. In paired bladders that were first stimulated with ADH for 30 min in the absence of a gradient, aggregates and fusion sites as well as osmotic water permeability determined in fixed bladders, persisted at near maximum levels for 15 min of washout in the absence of a gradient.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2003

Decapping and decay of messenger RNA occur in cytoplasmic processing bodies.

A major pathway of eukaryotic messenger RNA (mRNA) turnover begins with deadenylation, followed by decapping and 5' to 3' exonucleolytic decay. We provide evidence that mRNA decapping and 5' to 3' degradation occur in discrete cytoplasmic foci in yeast, which we call processing bodies (P bodies). First, proteins that activate or catalyze decapping are concentrated in P bodies. Second, inhibiting mRNA turnover before decapping leads to loss of P bodies; however, inhibiting turnover at, or after, decapping, increases the abundance and size of P bodies. Finally, mRNA degradation intermediates are localized to P bodies. These results define the flux of mRNAs between polysomes and P bodies as a critical aspect of cytoplasmic mRNA metabolism and a possible site for regulation of mRNA degradation.

Capsid Proteins↗
PubMed2006

Aggresomes and autophagy generate sites for virus replication.

The replication of many viruses is associated with specific intracellular compartments called virus factories or virioplasm. These are thought to provide a physical scaffold to concentrate viral components and thereby increase the efficiency of replication. The formation of virus replication sites often results in rearrangement of cellular membranes and reorganization of the cytoskeleton. Similar rearrangements are seen in cells in response to protein aggregation, where aggresomes and autophagosomes are produced to facilitate protein degradation. Here I review the evidence that some viruses induce aggresomes and autophagosomes to generate sites of replication.

Autophagy↗