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PubMed2000

Mitochondrial free calcium levels (Rhod-2 fluorescence) and ultrastructural alterations in neuronally differentiated PC12 cells during ceramide-dependent cell death.

Mitochondrial free calcium levels measured by Rhod-2 fluorescence and ultrastructure were examined during cell death in nerve growth factor (NGF)-differentiated PC12 cells that were 1) exposed to C2-ceramide, 2) deprived of serum to induce endogenous ceramide production, or 3) treated with calcium ionophore A23187. Rhod-2 fluorescence in mitochondria and also in the nucleolus increased to a maximum within 3 hours after C2-ceramide treatment or serum withdrawal. In A23187-treated cells, Rhod-2 fluorescence remained at baseline levels. In all three models, enlargement of the endoplasmic reticulum was the first ultrastructural alteration, followed by mitochondrial shrinkage in ionophore-treated cells, but by mitochondrial swelling in the ceramide-dependent models, in which rupture of the outer mitochondrial membrane and unfolding of the inner membrane were frequently seen. Dihydro-C2-ceramide, which did not cause cell death, had no effect on cellular ultrastructure. NGF, which inhibits ceramide-dependent cell death, prevented the effects of serum deprivation on mitochondrial ultrastructure but not on endoplasmic reticulum morphology or Rhod-2 fluorescence. Nuclear shrinkage with loss of nuclear membrane integrity, characterized by nuclear pores, free or surrounded by electron-dense filaments, was a late event in ceramide-dependent cell death. Chromatin condensation and other morphological features associated with apoptosis were seen in only a few atypical cells. Ceramide-mediated cell death, therefore, did not involve classical apoptosis but was mediated by a reproducible series of events beginning in the endoplasmic reticulum, followed by the mitochondria, and then the nucleus. NGF-dependent cell death inhibition intervenes at the mitochondrial level, not by blocking the increase in Rhod-2 fluorescence but by preventing the ultrastructural changes that follow.

Animals↗
PubMed2001

Characterization of ultrastructure and its relation with DNA fragmentation in Fas-induced apoptosis of cultured cardiac myocytes.

The purposes of the present study were to define precisely the ultrastructural features of apoptosis in cultured cardiomyocytes and to determine whether DNA fragmentation is essential for the apoptotic morphology. When cultured neonatal murine cardiomyocytes were incubated with an agonistic anti-Fas antibody in the presence of a non-toxic amount of actinomycin D or cycloheximide, approximately 70% of them had lost their viability after 24 h. The dead cardiomyocytes showed the typical ultrastructural changes of apoptosis on transmission and scanning electron microscopy, as well as by positive in situ nick end-labelling (TUNEL), positive Taq polymerase-based in situ ligation, a DNA ladder pattern on gel electrophoresis, and an increase in the active fragment of caspase-3. According to TUNEL at the electron microscopic level, apoptotic nuclear change, cytoplasmic shrinkage, and DNA fragmentation always occurred simultaneously in apoptotic cardiomyocytes. Other ultrastructural features of apoptosis were the appearance of abundant lipid-like structures in the cytoplasm of cardiomyocytes at the early phase, and a high incidence of plasma membrane rupture and formation of apoptotic bodies at the later phase. When zinc, an inhibitor of Ca2+/Mg2+-dependent endonuclease, was added to the present model, activation of caspase-3 and an apoptotic ultrastructure were still observed in spite of the lack of DNA fragmentation, indicating that this type of myocyte death is also apoptosis. In conclusion, the typical apoptotic ultrastructure and DNA fragmentation occur simultaneously in association with caspase-3 activation in Fas-stimulated cultured cardiomyocytes. Apoptotic morphology can, however, be observed even without DNA fragmentation.

Animals↗
PubMed1978

Ultrastructural studies on neuroblastoma: evaluation of cytodifferentiation and correlation of morphology and biochemical and survival data.

Fifteen cases of neuroblastoma, ganglioneuroblastoma and ganglioneuroma were studied by electron microscopy. Ultrastructural features of cytodifferentiation, including numbers of dense core neurosecretory granules (NSG) and neuritic processes, were used to evaluate variation within the neuroblastoma group to determine whether differences in cytodifferentiation exist where light microscopic variations are not evident. These studies revealed that undifferentiated neuroblastomas do show ultrastructural variations not evident by light microscopy. The ultrastructural findings for each case were compared with initial urinary catecholamine excretory patterns, the latter having recently been shown to have valuable prognostic significance. There was a positive correlation, in the undifferentiated neuroblastomas, between increased numbers of NSG and prognostically favorable biochemical excretory patterns. Conversely, low numbers of NSG were associated with an unfavorable biochemical pattern and fatal clinical course. These correlations between ultrastructural differentiation and the biochemical secretory pattern indicate that ultrastructural evaluation of undifferentiated neuroblastomas would appear to have prognostic value, particularly in cases lacking initial biochemical data or as an adjunct to biochemical studies.

Abdominal Neoplasms↗
PubMed2001

Garlic prevents ultrastructural alterations caused by dehydration in mouse cerebral microvessels.

Dehydration is known to significantly reduce both the time required for the first platelet aggregate and the time to full occlusion in photochemically-induced thrombosis, in vivo. Ultrastructural changes that contribute to such events remain unknown. Therefore, the effect of water deprivation for 24 hr, (as a model for dehydration) on the ultrastructure of mouse pial microvessels was investigated. The possible beneficial effect of garlic in preventing such ultrastructural changes was also investigated. Four groups of TO strain: control, control-garlic treated, dehydrated, and dehydrated-garlic treated male mice, 10/group, were used. Dehydration was induced by water deprivation for 24 hr. Garlic solution was i.p. injected at 0.1 ml/10g body weight. In urethane-anesthetized (2 mg/g, i.p.) mice, topical and transvessel bimodal fixation of pial microvessels was done with a phosphate buffered mixture of glutaraldehyde and paraformaldehyde, followed by a conventional electron microscopy procedure. Examination of control cerebral pial microvessels showed no evidence of cellular damage. Membranes of endothelial cells were intact. Within pial microvessels there was no evidence of platelet aggregation. Garlic treatments did not cause any ultrastructure abnormalities in control mice. Compared with control, dehydration caused the appearance of thrombi that consisted of platelet aggregates. Discoid platelets containing granules, spheroid degranulated platelets, and those with large pseudopodia were present in 80% of dehydrated mice. The venular endothelial surface of dehydrated mice revealed dilated profiles of endoplasmic reticulum and variously shaped vacuoles. Swelling of nuclear envelopes and mitochondrial distension were also present in dehydrated mice. Concomitant garlic treatment prevented most of these ultrastructural changes. These findings demonstrated the extent of damage to the pial microvessels in response to water deprivation and demonstrated the beneficial effect of garlic as a possible mean of protection against oncoming vascular pathology.

Animals↗
PubMed1983

Ultrastructural evidence of continued reorganization at the aging (11-26 months) rat soleus neuromuscular junction.

Ultrastructural remodeling, with evidence of focal deafferentation and reinnervation, occurs within normal young adult rat soleus neuromuscular junctions (Cardasis and Padykula, 1981). This may be related to normal variations in function. Recognition of this plasticity provides a basis for analysis of aging changes in junctional ultrastructure. Thirty soleus junctions were studied between 11 and 26 months of life. In these junctions, compared to younger ones (3-5 months) synaptic sites with the conventional ultrastructure become increasingly sparse. There is an increase in extent and frequency of exposed junctional folds, of intervention of Schwann cell cytoplasm between axon and junctional folds, and of numbers of lysosomes in all cytoplasmic profiles. Often primary clefts are shallow or missing, and secondary folds are widened and contain collagen. Features limited largely to these older junctions include highly pleomorphic myonuclei, deeply invaginated by myofibrils, and an increase in cellular profiles between basal lamina and sarcolemma. The identity of these profiles is unknown. At other locations within many of the same endplates, small intact terminals are associated with larger expanses of junctional folds, and several small terminals occur within the same primary cleft. Such terminals frequently contain dense-cored vesicles. These observations suggest continuation of some terminal axonal regeneration. Thus, the ultrastructure of these aging neuromuscular junctions reveals the same degenerative and regenerative events suggested by the ultrastructure of younger junctions, but suggests a shift in the balance between them.

Aging↗
PubMed1990

Early involvement of hepatic parenchymal cells in erythrohepatic protoporphyria? An ultrastructural study of patients with and without overt liver disease and the effect of chenodeoxycholic acid treatment.

Liver biopsy specimens obtained from two groups of erythrohepatic protoporphyria patients were studied histopathologically and ultrastructurally. Group 1 comprised seven erythrohepatic protoporphyria patients with a normal liver histology; from two patients liver biopsy specimens were available before and after 1 yr of chenodeoxycholic acid treatment. Group 2 consisted of four patients with a history of liver disease and liver histopathology; three patients were observed before and after 1 yr of chenodeoxycholic acid treatment. Liver specimens of nine kidney transplant donors served as controls. Unlike the morphology at the light microscopic level, the ultrastructure of hepatic parenchymal cells was affected in both groups of erythrohepatic protoporphyria patients. In both groups the nuclei, endoplasmic reticulum, lateral plasma membranes and bile canaliculi were altered. Collagen fibers were frequently present. In addition, in group 2 bile thrombi and intracytoplasmic protoporphyrin crystals were observed. After chenodeoxycholic acid administration, the latter feature had diminished. It is concluded that (a) in erythrohepatic protoporphyria ultrastructural changes are present in the hepatic parenchymal cells even in early stages of the disease. Changes in bile canalicular ultrastructure suggest a defective hepatic excretory function, probably caused by the toxic effect of protoporphyrin. (b) Chenodeoxycholic acid administration causes no distinct improvement of the ultrastructure of organelles in the hepatic parenchymal cell or the bile canalicular system but may decrease crystalline protoporphyrin deposition in the liver.

Adolescent↗
PubMedDate not supplied

Recovery of normal testicular ultrastructure and sperm motility after cessation of gossypol treatment in rats.

This study evaluates the reversibility of the effects of gossypol on testicular ultrastructure and the motility of epididymal spermatozoa. Adult male rats were treated 6 days weekly with the vehicle alone (Group A), or with 10 (Group B) or 20 (Group C) mg/kg of gossypol for 12 weeks, and then sacrificed six or 12 weeks after cessation of treatment. Although epididymal spermatozoa in Groups B and C were 100% immotile after gossypol treatment, little evidence of abnormality could be detected with the light microscope in the seminiferous tubules or interstitium. By contrast, at the ultrastructural level, there were demonstrable pathognomonic defects in the mitochondrial sheath and axonemes of step 18 and 19 spermatids which were identical to those reported earlier (Hoffer, 1983). In addition, an ultrastructural defect in the flagella of late testicular spermatozoa is described for the first time. This defect consists of an indentation, or constriction, of the mitochondrial sheath at outer dense fibers (ODFs) 1, 2, and 9, resulting in a separation of these 3 ODFs from the other fibers. This defect, though visible in an earlier ultrastructural study (Hoffer, 1983), was not described. In Group B rats allowed to recover from gossypol treatment, ultrastructural defects in step 18 and 19 spermatids could not be detected at six or at 12 weeks after cessation of treatment, and sperm motility also did not differ significantly from controls by the end of either recovery period. In Group C rats, sperm motility returned to the normal range within six weeks after treatment ended, but a few morphological defects in the midpiece and axoneme of late spermatids could still be detected with the electron microscope.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Renewal of the intestinal epithelium: new aspects as indicated by recent ultrastructural observations.

This article is a summary of our work of several years on the renewal of the intestinal epithelium. A combination of ultrastructural, radioautographic, and light microscopic analyses was carried out using normal tissue and tissue affected by inhibitors of RNA and protein synthesis. Measuring protein synthesis by 3H-leucine radioautography showed that the life span of the columnar (absorptive) cells in the rat small intestine was divisible into two main phases: differentiation (from stem to functional cell) and maturation (from functional to extruding cell), each phase and its subdivisions being well defined morphologically. Differentiation involved a linear rise in the rate of protein synthesis per cell and showed at the same time heterochromatinization and silencing of RNA transcription. Data from various experiments indicated that the cells functioned from stored information (RNA), part of which came from the nucleolus, which underwent marked and characteristic ultrastructural changes. Although transcription from rDNA ceased, the nucleolus released its ribosomal material, which added to the existing protein synthesis, presumably by recruiting excess stored mRNAs. Maturation involved a nearly linear decrease of the rate of protein synthesis per cell to a characteristic low value at which extrusion took place. A gradual exhaustion of the stored RNA was indicated to be the key factor in this decrease. Ultrastructurally, maturation was associated with a gradually increasing vesiculation of rER and Golgi. The results thus imply a regulatory role of cellular protein synthesis level in renewal. This would be an epigenetic response after the genes are silenced. The nucleolus seems to play a central role in this process, and this in turn is reflected in its characteristic ultrastructural changes. The work also included new observations on the epithelium of the rat ascending colon describing a hitherto unrecognized deep crypt mucus-secretory ("DCS") cell which is a nongoblet mature cell type apparently arising from midcrypt mitoses. In between the DCS cells, occasional slender columnar cells were seen which displayed the ultrastructural features of stem cells. These were probably reserve stem cells. We also observed nongoblet deep crypt mucous cells in the human right colon although fewer in number than in the rat. Nucleolar regulation and the presence of reserve stem cells represent new dimensions in our understanding of renewal. Electron microscopy is an essential tool in this investigation.

Animals↗
PubMed1996

Ultrastructural changes in canine lung preserved in newly developed solutions.

The present study was undertaken to clarify the effect of differences in the ionic composition of a preservation solution by investigating ultrastructures of pulmonary endothelial cells and oxygenation ability of preserved lungs after reperfusion. The relation between the ultrastructural changes and the oxygenation ability was also examined. Canine lungs flushed with an extracellular-type (ET)-Kyoto solution (group A, n = 6), with an intracellular-type-Kyoto solution and prostaglandin El (group B, n=6), or with Euro-Collins solution and prostaglandin E1 (group C, n=6) were stored at 4 degrees C for 20 hr. In transmission electron microscopic findings, the frequency of ultrastructural changes (protrusion of endothelial cells and cellular vacuolization) was significantly less in group A (23.3 +/- 9.1 and 13.3 +/- 5.2%, respectively) than in group B (64.4 +/- 6.1 and 42.2 +/- 8.8%, respectively). In group A, PaO2 after 40, 70, and 130 min of reperfusion was uniformly excellent (289.4 +/- 5.7, 303.3 +/- 7.0, and 303.0 +/- 19.6 mm Hg, respectively) and significantly higher than in groups B and C (202.6 +/- 32.0 and 185.9 +/- 23.0 mm Hg, respectively) after 70 min and higher than in group C (155.7 +/- 36.3 mm Hg) after 130 min of reperfusion. A negative correlation was noted between the frequency of cellular vacuolization and the PaO2 after reperfusion. These results indicated that extracellular ion composition has significantly better effect on pulmonary vascular ultrastructures than intracellular ion composition. This may be a factor making ET-Kyoto solution superior to the other two solutions in oxygenation ability after reperfusion. When attempting to develop better lung preservation solution, the ability to preserve the ultrastructures of preserved lung may be an important consideration in the evaluation.

Animals↗
PubMed1995

Ultrastructural characterization of the sexually dimorphic medial preoptic nucleus of male Japanese quail.

The medial preoptic nucleus is a sexually dimorphic structure whose cytoarchitecture, afferent and efferent connections, and functions have been previously described. No detailed ultrastructural study has, however, been performed to date. Here we describe the ultrastructural organization of this important preoptic structure of the male quail. Neuronal cell bodies of the medial preoptic nucleus generally show extensive development of protein-synthesis-related organelles (rough endoplasmic reticulum, polysomes), and of secretory structures (Golgi complexes, secretory vesicles, dense bodies). Previous morphometrical studies at the light-microscopical level have demonstrated the presence of a medial and a lateral neuronal population distinguished by the size of their cell bodies (the medial neurons are smaller than the lateral neurons). The present ultrastructural investigation confirms the difference in size, but no difference has been observed in the ultrastructural organization of the neurons. In both the medial and the lateral part, the nucleus is characterized by a large variety of cell bodies, including some that, on the basis of their ultrastructure, can be considered as putative peptidergic neurons. Close contacts are frequently observed between adjacent cell bodies that are normally arranged in clusters. Various types of synaptic endings are also present, suggesting a rich supply of nerve fibers. A few glial cells are scattered within the nucleus. In view of the crucial role of this region in regulating quail sexual behavior, the large heterogeneity of neurons and of afferent nervous fibers suggest that this region might have an important role in the integration of information arriving from different brain regions.

Animals↗
PubMed1986

Ultrastructure of lymphocytes from patients with paracoccidioidomycosis in the lymphocyte transformation test by phytohemagglutinin.

The morphology and ultrastructure of peripheral blood lymphocytes from patients with paracoccidioidomycosis (PCM) and from unaffected individuals (controls) were studied before and after Ficoll-Hypaque separation and at the end of culture, stimulated with phytohemagglutinin. Patient lymphocytes were cultured in medium with autologous plasma (from the patient himself) and with homologous plasma (from an unaffected donor), while donor lymphocytes were cultured in medium with plasma from a patient or with plasma from the donor himself. The Ficoll-Hypaque mixture caused no morphological or ultrastructural changes in the lymphocytes of patients or of unaffected donors. Patient lymphocytes cultured in medium with autologous plasma showed different degrees of cytoplasmic and nuclear alterations, such as organelle dissolution, vacuoles, amorphous masses, deformed nuclei, and absence of nucleoli. Lymphocytes from control individuals cultured in patient plasma also showed ultrastructural alterations, though they were less marked, and a reduced number of 'blasts'. Patient lymphocytes cultured in medium with homologous plasma (from a control individual) showed a morphology similar to that of lymphocytes from control individuals cultured in medium with their own plasma, although with a lower number of 'blasts'. On the basis of the results obtained using that methodology, we draw the following conclusions: separation by Ficoll-Hypaque does not seem to alter the ultrastructure of patient or donor lymphocytes; patients with diffuse PCM and more markedly impaired general condition can exhibit lymphocytes with morphological and ultrastructural alterations capable of affecting their biological systems and functionality.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Ultrastructural and histochemical evidence for differentiation of intraocular locus coeruleus grafts and invasion of the host iris by central neurites and glia.

Intraocular grafts of dorso-lateral pons, including the noradrenaline-containing cell group locus coeruleus, have been studied with ultrastructural and histochemical techniques. Also, the invasion of neuronal and glial constituents from the grafts into the iris of the host animal is described. In mature brain grafts, aggregates of locus coeruleus neurons were easily discernible with monoamine histofluorescence. These cells had an ultrastructural appearance very similar to that in situ. Numerous somatic spines were frequently associated with synaptic specializations, and monoamine-containing vesicles could be found scattered in the cytoplasm of the locus coeruleus cells. Large neurons of the nucleus tractus mesencephalici nervi trigemini were also found. These cells were neurofilament-immunoreactive just as in situ, and were ultrastructurally characterized by size, distribution of the granular endoplasmic reticulum and abundant large terminals in synaptic contact with their somata and processes. All grafts showed a vigorous astroglial proliferation, evidenced both with immunohistochemistry of glial fibrillary acidic protein and electron microscopy. The astroglial cells were more numerous, larger and with more processes than in adult in situ counterparts. At the attachment site of the brain stem grafts, the iris dilator plate was entirely changed ultrastructurally by a vigorous invasion of neuronal and astrocytic processes. The normal, loose connective tissue stroma of the iris was replaced by layers of almost exclusively central nerve fibres and astrocytes respectively. Monoamine histofluorescence demonstrated an extreme adrenergic hyperinnervation of the iris at the attachment site of the graft, compared to the normal sympathetic ground plexus, whereas neurofilament immunohistochemistry did not visualize any substantial ingrowth of such positive central nerve fibres. Immunohistochemistry of glial fibrillary acidic protein strongly supported the ultrastructural evaluation, showing profound astroglial invasion deep into the iris stroma. Electron microscopic identification of central nerve fibres in the iris showed numerous adrenergic locus coeruleus fibres with small dense-core vesicles. Also, bundles of thin, central, unmyelinated axons were found deep in the iris as well as occasional dendrites. Both large dense-cored and small clear vesicles were encountered in the iris fibres of brain graft origin. Axo-dendritic synaptic specializations formed by locus coeruleus-derived adrenergic fibres were found in the iris.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Ultrastructure and synaptic relationships of calbindin-reactive, Dogiel type II neurons, in myenteric ganglia of guinea-pig small intestine.

Immunoreactivity for calbindin D 28K was localized ultrastructurally in nerve cell bodies and nerve fibres in myenteric ganglia of the guinea-pig small intestine. Reactive cell bodies had a characteristic ultrastructure: the cytoplasm contained many elongate, electron-dense mitochondria, numerous secondary lysosomes that were peripherally located, peripheral stacks of rough endoplasmic reticulum and dispersed Golgi apparatus. The cells were generally larger than other myenteric neurons and had mainly smooth outlines. The cytoplasmic features of these neurons were shared by a small group of immunonegative cells, but the majority of negative cells had clearly different ultrastructural appearances. Of 310 cells from 16 ganglia that were systematically examined, 38% were immunoreactive for calbindin, 10% were unreactive but similar in ultrastructure to the calbindin-reactive neurons and 51% were unreactive and dissimilar in the appearance of their cytoplasmic organelles. Immunoreactive varicosities with synaptic specializations were found on most unreactive neurons, but were markedly less frequent on the calbindin-immunoreactive cell bodies. Non-reactive presynaptic fibres were also more common on non-reactive neurons than on the calbindin-positive cell bodies. Numerous reactive varicosities, some showing synaptic specializations, were found adjacent to other fibres in the neuropil. Light microscopic studies show calbindin immunoreactive neurons to have Dogiel type-II morphology. Thus the present work links distinguishing ultrastructural features to a specific nerve cell type recognized by light microscopy in the enteric ganglia for the first time.

Animals↗
PubMed2004

Ultrastructural study of benign, low-malignant potential (LMP), and malignant ovarian tumors.

Ultrastructural characteristics of benign, low-malignant potential (LMP), and malignant ovarian tumors were investigated, considering the aspects of histologic subtypes and histologic grading. In addition, the histogenesis of ovarian cancer was histologically investigated in an attempt to elucidate whether malignant tumor was generated from benign or LMP tumor, or whether it was generated de novo from normal tissues. Although all the benign, LMP, and malignant tumors appeared to be derived from Mullerian duct in serous tumors, the origin of endometrioid or mucinous tumor could not be ultrastructurally clarified. However, there was ultrastructural similarity between benign and malignant tumors among serous, endometrioid, and mucinous tumors, and it was suggested that benign adenoma may be the developmental origin of malignant tumors regardless of the histologic subtype. In addition, the investigation of endometrioid tumors revealed that the differences of histologic grading in malignant tumors reflected the ultrastructural differences, and that G1 tumor had an ultrastructure that was more similar to that of benign and LMP tumors than to that of G2 tumor.

Animals↗
PubMed1987

A quantitative analysis of blood-brain barrier ultrastructure in the aging human.

The unique ultrastructure of brain endothelial cells restricts nonspecific leakage of blood-borne molecules across the blood-brain barrier (bbb). Human barrier ultrastructure has not been studied extensively because of the rapid ultrastructural degeneration that takes place after death. We have obtained living, structurally normal neocortex and underlying white matter at biopsy from patients of various ages, and have quantitated ultrastructural features that are associated with the bbb so that we could characterize human barrier ultrastructure and determine whether it changes with age. We found that gray matter capillaries have thinner walls than white matter capillaries, and that during aging white matter capillary walls became thinner until they approached the dimensions of those in gray matter. Thinning is due to loss of pericytes and thinning of the endothelial cytoplasm. The mitochondrial density was found to be higher in gray matter than in white matter, but this is a consequence of there being a smaller cytoplasmic volume and not more (or larger) mitochondria. The mitochondrial population did not change with age. Presumptive nonspecific permeability routes (endothelial vesicles, junctional gaps) did not change with age; therefore we found no morphological substrate for increased nonspecific bbb permeability in the aging human. The loss of pericytes, however, suggests that the bbb in the elderly may be less able to compensate for transient leaks.

Aging↗
PubMed1985

Methyl mercury and selenium interaction in relation to mouse kidney gamma-glutamyltranspeptidase, ultrastructure, and function.

The effects of methyl mercury (CH3Hg) and selenium (Se) on renal ultrastructure were investigated and correlated to changes in renal gamma-glutamyl transpeptidase (gamma-GTPase) activity, mercury (Hg) accumulation, and renal function (serum creatinine and urea nitrogen). Three experimental protocols were used to investigate CH3Hg and Se interactions of both Se-sufficient and Se-deficient mice involving ip injection of the following administered alone or in combination: CH3Hg (4.0 mg/kg) and Se (0.16 mg/kg) daily for 7 days, CH3Hg (1.0 mg/kg) and Se (0.08 mg/kg) daily for 20 days, and a single acute dose of CH3Hg (8.0 mg/kg). Acivicin (12 to 50 mg/kg), an antitumor glutamine antagonist, was also used as a highly effective specific inhibitor of the gamma-GTPase. Our results show that CH3Hg administered to Se-deficient mice for 7 or 20 days resulted in significant (p less than or equal to 0.05) but only moderate inhibition (20%) of gamma-GTPase activity and extensive renal ultrastructural damage. Acivicin-treated mice had significant inhibition of gamma-GTPase activity (80%) following a single injection while ultrastructural damage was substantial only after several days of administration. These results may indicate different modes of action of acivicin and CH3Hg. Acivicin inhibited gamma-GTPase prior to renal damage while CH3Hg produced greater pathological effects with only moderate gamma-GTPase inhibition. Renal damage from acute and chronic CH3Hg toxicity occurred after distinct neurological signs were present. Selenium administered to Se-deficient mice ameliorated both the neurotoxic effects and nephrotoxic action of CH3Hg. While Se and CH3Hg treatments caused some of the same ultrastructural pathology as the treatment with CH3Hg alone (cytoplasmic vacuolation, increased lysosomal profile, mitochondrial swelling, and extrusion of cellular masses into the tubular lumen), degeneration was not as extensive. Although the total doses administered during both the 7- and the 20-day studies were similar, mice from the chronic 20-day study showed greater ultrastructural pathological effects from CH3Hg. The primary effects of CH3Hg appeared to be on the lysosomal system, while acivicin exerted its effects on the mitochondrial and endoplasmic reticulum systems. The accumulation studies on Hg suggest that dietary Se may have only an initial protective effect against Hg accumulation in the kidney while injected Se offers longer protection.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

Chondroid lipoma: an ultrastructural and immunohistochemical analysis with further observations regarding its differentiation.

Chondroid lipoma was recently described as a unique, benign, pseudosarcomatous lipomatous tumor with chondroid features, often simulating liposarcoma and myxoid chondrosarcoma. An extended histochemical and immunohistochemical analysis of 13 cases, including the proliferation markers, proliferating cell nuclear antigen (PCNA) and Ki67, as well as ultrastructural studies of eight cases were performed with the intent of further elucidating its differentiation. Staining with toluidine blue and alcian blue at controlled pHs indicated the presence of chondroitin sulfates within the myxohyaline matrix. Immunohistochemically, all tumors were positive for vimentin and S100 protein. Focal immunoreactivity for cytokeratins was seen in 3 of 13 cases; one of these also had intracytoplasmic tonofilament bundles ultrastructurally. Scattered tumor cells stained for CD68 antigen with KP1 in 6 of 13 cases. None of the tumors stained for epithelial membrane antigen (EMA) or alpha-smooth muscle actin. Collagen IV immunostains showed a network of fibrils encircling individual tumor cells in 10 of 13 cases. Intracytoplasmic staining for laminin was found in 9 of 13 cases. Ultrastructurally there was a spectrum of differentiation, ranging from primitive cells sharing features of prelipoblasts and chondroblasts, to lipoblasts and preadipocytes, to mature adipocytes. A striking ultrastructural feature in 5 of 8 cases was the presence of knob-like protrusions of the cell membrane, which contained granular, amorphous, and fibrillar material that appeared to be extruded into the adjacent matrix. The myxohyaline matrix had ultrastructural features of cartilage. Numerous mitochondria and lysosomes were absent, indicating that chondroid lipoma is neither a hibernomatous lesion nor a lipogranuloma. Ki67 immunoreactivity was typically very low and detected only in the more primitive cell population. The findings in this analysis indicate that chondroid lipoma is a pseudosarcomatous lipogenic neoplasm with a unique cell population possessing predominantly features of embryonal fat and, to a lesser extent, embryonal cartilage.

Adolescent↗
PubMed1990

Ultrastructure of E1 + 2 + 9 + 12 inversion breakpoints in Drosophila subobscura.

The ultrastructure of the Drosophila subobscura chromosome regions around the breakpoints of the complex E1 + 2 + 9 + 12 gene arrangement was analyzed. This overlapping inversion is formed by the association of the E1, E2, E9, and E12 simple inversions. Ultrastructure of sections involving 58D/59A, 61C/D, 62D/63A, 64B/C, 67A/B, and 68B/C breakpoints on Est chromosomes were compared with the ultrastructure of sections involving chromosomes were compared with the ultrastructure of sections involving 58D/68B, 62D/64C, 59A/63A, 64B/68C, 67B/61C, and 67A/61B breakpoints on E1 + 2 + 9 + 12 chromosomes. No detectable changes of structural organization on banding patterns induced by the E1 + 2 + 9 + 12 inversion were found. Ultrastructural analysis of the two E12 breakpoints has, however, facilitated the analysis of the left boundary of E12 inversion. Accordingly, we propose 61B/C as a new breakpoint instead of 61C/D.

Animals↗