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PubMedDate not supplied

Ultrastructural localization of collagen IV, fibronectin, and laminin in the trabecular meshwork of normal and glaucomatous eyes.

PURPOSE: To determine whether differences in the ultrastructural characteristics or composition of the basement membranes of the trabecular lamellae and Schlemm's canal exist in normal eyes and eyes with primary open-angle glaucoma (POAG). Basement membranes play key roles in the attachment of the overlying trabecular cells and Schlemm's canal cells. METHODS: Electron microscopy used in conjunction with immunogold labeling was used to examine the ultrastructure of the basement membranes in the trabecular meshwork and to determine the presence of collagen IV, laminin, and fibronectin in 6 normal eyes and 6 eyes with POAG. To determine which cells in the meshwork synthesized these molecules in situ hybridization was studied in an additional 8 normal eyes. RESULTS: No distinctive ultrastructural changes were found in the basement membranes of glaucomatous eyes, whether early or advanced disease, when compared with normal eyes. Label for all three proteins was present in the basement membranes of the trabecular lamellae, Schlemm's canal, and in scattered patches within the juxtacanalicular tissue. Laminin and fibronectin were most abundant in the periphery of the sheath material surrounding the elastic tendons in the juxtacanalicular tissue. In contrast to previously published light microscopic studies, no increase in fibronectin was found in glaucoma. Regions of the basement membrane of the canal underlying giant vacuoles were similar to regions without giant vacuoles in both appearance and labeling. In situ hybridization revealed that mRNA for all three proteins was present in most trabecular cells throughout the meshwork; no regional differences in cellular labeling within were observed. CONCLUSION: The ultrastructural characteristics and immunogold labeling of basement membranes were similar in normal and glaucomatous eyes; no additional structures were labeled in POAG eyes that were not also labeled in normal eyes. Label of the patches of amorphous fibrogranular material within the juxtacanalicular tissue suggests it is basement membrane in origin, while the sheath material which is known to accumulate in POAG was not heavily labeled and does not appear to be basement membrane in origin.

Aged↗
PubMed1997

Pneumocytes type II ultrastructural modifications after storage in preservation solutions for transplantation.

Although lung transplantation represents a real therapeutic opportunity, the problem of preserving the organ for a prolonged period (> 10 h) still remains unsolved. Further studies are necessary to fully understand the behavior of different lung cell types during the ischemic period. As ultrastructural modifications of cells of lung samples stored in different means of preservation represent an index of the integrity and therefore of cellular viability, in the present work we have compared the time-related ultrastructural changes in human pneumocytes type II cells after hypothermic (10 degrees C) storage for 6 and 12 h in University of Wisconsin (UW) solution and in low potassium dextran (LPD) solution. An ultrastructural grading scale was used to quantify the damage and the results confirmed what was observed microscopically. Statistical analysis (t test) of the data showed that after 6 h in LPD solution, pneumocytes type II were less damaged than those stored in UW solution; these differences were statistically significant (p < 0.05). In our opinion, ultrastructural studies should be considered among the methods presently used to assess the effectiveness of different storage fluids.

Adenosine↗
PubMed1984

Effect of the removal of different endocrine glands upon insulin secretion and B-cell ultrastructure.

Glucose-induced insulin secretion and B-cell ultrastructure were studied in islets obtained from normal, adrenalectomized, radiothyroidectomized, ovariectomized and orchidectomized rats. Both parameters were also studied in the same experimental groups submitted to specific substitutive therapy. Insulin secretion in response to high glucose was significantly diminished in adrenalectomized, hypothyroid and male castrated rats. Conversely, this secretion was enhanced in ovariectomized rats. These abnormal insulin responses were restored to normal range by specific substitutive therapy. B-cell ultrastructure was markedly altered in hypothyroid and in female and male castrated rats. No significant changes were observed in the adrenalectomized rats. No conspicuous alterations were depicted in the other islet cell populations. The features of the morphological alterations were mainly related to changes in the B-granules and the rough endoplasmic reticulum. Modifications of the other B-cell organelles were less frequent. In the castrated rats, a distinctive feature was the appearance of a finely granulated colloid material. These B-cell alterations, consecutive to changes in the circulating levels of a given hormone, seemed to depend on the chemical structure of the hormone itself rather than on the changes induced in the B-cell secretory function. The ultrastructural changes described were reversed, as in the case of insulin release, by specific substitutive therapy. It is concluded that changes in the circulating levels of the hormones studied are followed by specific alterations in both B-cell secretion and ultrastructure.

Adrenalectomy↗
PubMed1994

Ultrastructure of the heart muscle in rats under hypobaric stress and under high NaCl intake.

Cellular metabolic alterations in the heart have been widely investigated under a variety of experimental conditions in which the oxygen supply was diminished. However, there is relatively scarce information about the effect of the reduced food intake and saline loading on the ultrastructural changes occurring in myocardial cells exposed to hypobaric stress during short periods of time. The purpose of the present study was to analyze the effects of hypobaric stress, NaCl intake and undernourishment on the body and heart weights and the ultrastructural changes produced in the rat myocardial cells under these conditions. The body and heart weights in all the experimental groups were determined as well as the total and mitochondrial protein concentrations. A significant decrease in body and cardiac weights was observed in both groups of undernourished animals submitted to hypobaric stress or not. On the other hand, a slight increase in the mitochondrial protein concentration was obtained in the same groups. Cardiac muscle samples were processed for light- and electron-microscopic observations. Few ultrastructural alterations were seen in the experimental groups fed with a standard diet; however, an increase in the mitochondrial size was shown in the rats that received 0.9 and 1.3% NaCl solutions. In the groups of animals with one third of the normal protein-calorie intake, more intense changes were noted; disappearance of the contractile structures, with almost complete extinction of the Z bands, was commonly observed in the rats submitted to hypobaric stress. The ultrastructural alterations seen in the undernourished animals were even more evident, showing generalized damage to the intracellular components.

Animals↗
PubMed1996

Distinctive ultrastructural pathology of nonulcerative interstitial cystitis: new observations and their potential significance in pathogenesis.

Ultrastructural study of the bladder in interstitial cystitis has, so far, been limited, mainly to the urothelium. The present study was conducted first to study in detail the ultrastructural features of all tissue components of the bladder wall in nonulcerative interstitial cystitis and second to derive clues from the observed changes to pathogenesis of the disease. Endoscopic biopsies of urothelium with attached suburothelium, and muscularis, were obtained from both lesional and nonlesional areas in 5 female patients with unequivocal clinical diagnosis of interstitial cystitis. The specimens were processed for electron microscopic study by standard methods and subjected to comprehensive ultrastructural study of urothelium, suburothelium, detrusor muscle cells, intrinsic blood vessels, and intrinsic nerves. A distinctive combination of peculiar muscle cell profiles, injury of intrinsic vessels and nerves in muscularis and suburothelium, and discohesive urothelium was observed in lesional and less markedly in nonlesional samples of all specimens. Marked edema of various tissue elements and cells appeared to be a common denominator of many observed changes. Edema of muscle cells resulted in characteristic querciphylloid profiles, so designated because of peripheral bosselation of cell sarcoplasm with a lobed perimeter resembling that of an oak leaf. Urothelial changes disrupted the true permeability barrier, consisting of asymmetric unit membrane and triple epithelial junctions of surface (umbrella) cells. Vascular lesions included endothelial cell injury and suggested sluggishness of intrinsic microcirculation. Neural changes included a combination of degenerative and regenerative features, some expressing neural plasticity. The observed ultrastructural changes appear to be sufficiently distinctive to be diagnostic in specimens submitted for pathologic confirmation of nonulcerative interstitial cystitis. The changes do not support a primary pathogenetic role of mast cells or a selectively deficient glycosaminoglycan layer. They do suggest, however, a pathogenesis based on a potentially self-perpetuating process of neurogenic inflammation that can trigger a biologically potent cascade of events, including a leaky urothelium and mast cell activation. As proposed, neurogenic inflammation consolidates various proposals advanced as the pathogenesis of interstitial cystitis and can readily accommodate infectious, immunologic, and autoimmunologic mechanisms as factors that contribute to development or chronicity of the disease.

Adult↗
PubMed1994

Ultrastructural findings and SOD levels in experimental optic nerve injury: effect of thyroid-releasing hormone on the degenerative and regenerative processes.

We performed pressure on the left optic nerves of 24 pigs and injected intravenous thyroid-releasing hormone (TRH) to 12 of these pigs in order to evaluate the degeneration and regeneration in the optic nerves. The histopathologic, ultrastructural and biochemical examinations of the optic nerves were made at the 24th hour, 7th, 15th and 30th days. Although the light-microscopic examinations were normal, ultrastructural changes of the uncompressed optic nerves were interesting. Histopathologic and ultrastructural investigation of the compressed optic nerves showed significant degenerative changes in the non-TRH-applied group. Ultrastructural comparison yielded lighter degenerative changes in the TRH-applied group but there was no clue showing the stimulation of regeneration. We observed increased superoxide dismutase (SOD) levels in the nontraumatized optic nerves due to the cellular stress. The SOD values were found to be low in highly damaged left compressed optic nerves indicating the prevention of SOD enzyme synthesis.

Animals↗
PubMed1995

Early clinical and ultrastructural effects of diltiazem injection on rabbit extraocular muscles.

We injected diltiazem into the left lateral rectus muscles (LR) of 10 rabbits in order to examine the ultrastructural effects of diltiazem on rabbit extraocular muscles and estimate its advantages in clinical use as an alternative to the surgical therapy of strabismus. The animals were divided into two groups according to the time of evaluation following the injection. The LR muscles of both eyes of the first group were respected 60 min after the injection, for ultrastructural examination. The same procedure was done for the second group at the 24th hour. The right eyes were used as the control group. There was a medial shift 3-5 min following the injection in the left eyes of both groups. The ultrastructural examination revealed weakness in muscle contractility, probably as a result of inhibition of glycogen usage due to calcium accumulation. In this study, we examined the early clinical and ultrastructural effects of diltiazem.

Animals↗
PubMed2002

Sensitivity to apoptosis signal, clearance rate, and ultrastructure of fas ligand-induced apoptosis in in vivo adult cardiac cells.

BACKGROUND: Sensitivity to apoptotic signals, the clearance rate of apoptosis, and the apoptotic ultrastructure have not been studied in cells of the in vivo adult heart. METHODS AND RESULTS: To minimize the systemic influence, soluble Fas ligand was injected directly into in vivo rat hearts and livers (as the control) at concentrations of 0, 0.5, 2, and 5 microg/mL (groups C, F0.5, F2, and F5). Apoptotic cardiomyocytes and apoptotic noncardiomyocytes of the heart were identified with similar incidences only in F5. Their incidences peaked at 12 hours after injection (2.0+/-0.09% in cardiomyocytes) and diminished markedly 24 hours later. Caspase-3 was activated only in F5. Boc-Asp-fmk, a pancaspase inhibitor, inhibited apoptosis, suggesting that the apoptosis sensitivity was regulated upstream of caspase-3. Apoptotic noncardiomyocytes showed typical ultrastructure. In addition to the typical ultrastructure, such as cellular shrinkage, chromatin condensation, and apoptotic bodies, however, apoptotic cardiomyocytes showed unique features: doughnut-like, but not half-moon- or crescent-like, chromatin condensation; frequent plasma membrane rupture even during the early stage; condensed mitochondria with wrinkled cristae inside; the appearance of cytoplasmic lipid-like droplets; and myofibrillar derangement. In the livers, typical apoptosis was induced in hepatocytes and nonhepatocytes of the liver even in the F0.5 group, which were cleared 24 hours later. CONCLUSIONS: Compared with liver cells, cardiomyocytes as well as noncardiomyocytes of the heart are more resistant against the apoptotic signal, but the clearance is similarly rapid (within 24 hours). The ultrastructure of apoptotic cardiomyocytes is unique. These findings provide new insights into the dynamics of cell death in the heart.

Animals↗
PubMed2006

Ultrastructural changes after artificial retinal detachment with modified retinal adhesion.

PURPOSE: Artificial retinal detachment is increasingly used in submacular surgery. However, overcoming physiological retinal adhesiveness by subretinal fluid injection is suspected to cause cellular damage and thus to limit visual rehabilitation. This experimental study was designed to examine the ultrastructural changes induced by retinal detachment under vitrectomy conditions and to evaluate factors that reduce adhesiveness and minimize cellular damage. METHODS: Twenty-one pigmented rabbits underwent vitrectomy, and the vitreous cavity was perfused for 10 minutes with various solutions. These included variations in osmolarity (314 and 500 mOsM), Ca(2+) ion concentration (Ca(2+)-supplemented, low Ca(2+), active Ca(2+) deprivation via 1 mM EDTA), temperature (19 degrees C and 34 degrees C), and ischemia (5 minutes). Nonvitrectomized eyes served as the control. Consecutively, an artificial bleb detachment was created underneath the visual streak by injecting 1 mL of buffered saline solution subretinally. Eyes were enucleated within 3 minutes, fixed with 2% glutaraldehyde/0.1 M cacodylate buffer (pH 7.4) containing 100 mM sucrose and processed for transmission electron microscopy and scanning electron microscopy. RESULTS: If a Ca(2+)-containing standard solution was used during vitrectomy, retinal adhesiveness was strong, and a forced bleb detachment caused substantial cellular damage characterized by swollen and fragmented photoreceptor outer segments and disruption of retinal pigment epithelial cells. Use of a Ca(2+)-free solution moderately reduced the adhesive strength with consequently less ultrastructural damage. Active Ca(2+)-deprivation further reduced the retinal adhesion, but may have induced damage as suggested by intracellular vacuolization. Hyperosmolarity and ischemic conditions had toxic effects on both the photoreceptors and RPE cells. In contrast, the use of a preheated Ca(2+)-free solution (34 degrees C) substantially reduced retinal adhesiveness under vitrectomy conditions and hence ultrastructural damage. CONCLUSIONS: Artificial retinal detachment causes substantial ultrastructural damage in eyes with physiological retinal adhesiveness if performed under vitrectomy conditions similar to surgery in humans. The use of a preheated Ca(2+)-free physiologic saline solution seems to be suitable to reduce retinal adhesion sufficiently, without causing significant cellular damage.

Adhesiveness↗
PubMedDate not supplied

Acquired ultrastructural alterations of respiratory cilia and clinical disease. A review.

Efficient cleansing of the upper and lower respiratory surfaces by the mucociliary apparatus is essential to health. Failure of the cleansing allows contaminants prolonged residence on the mucosal respiratory surfaces and thus penetration into the mucosa and possibly inauguration of disease. For some years, genetic ultrastructural ciliary alterations have been recognized, with symptoms dating from early life. It is only in recent years, however, that evidence has shown that ultrastructural ciliary alterations can be acquired later in life and that these alterations in turn lead to a deterioration of efficient ciliary cleansing. A discussion of the ultrastructure of the normal mammalian cilium will be given, as well as a listing of the genetic ciliary disease and their characteristic morphologic alterations. A more complete review will be made in regard to acquired ciliary defects, their cause, the ultrastructural changes, and the relation to clinical disease.

Cilia↗
PubMed1991

Ultrastructural and cytochemical evidence for single impulse initiation zones in vestibular macular nerve fibers of rat.

Cupric ion-ferricyanide labeling methods and related ferrocyanide-stained tissues were used to locate and characterize, at the ultrastructural level, presumptive impulse initiation zones in the three types of vestibular macular nerve fibers. Large-diameter, M-type vestibular nerve fibers terminate in a calyx at the heminode, and labeling is coextensive with the base of the calyx. Intermediate, M/U-type nerve fibers have short, unmyelinated preterminal segments that sometimes bifurcate intramacularly, and small-diameter, U-type nerve fibers have long, unmyelinated preterminal axons and up to three branches. Preterminals of these nerve fibers display ultrastructural heterogeneity that is correlated with labeling patterns for sodium channels and/or associated polyanionic sites. They have a nodelike ultrastructure and label heavily from near the heminode to the base of the macula. Their intramacular branches, less organized ultrastructurally, label only slightly. Results indicate that vestibular nerve fibers have one impulse initiation zone, located near the heminode, that varies in length according to nerve fiber type. Structural heterogeneity may favor impulse conduction in the central direction, and length of the impulse initiation zone could influence nerve discharge patterns.

Acoustic Maculae↗
PubMed1995

Iatrogenic compressive lumbar myelopathy and radiculopathy in adult cattle following injection of an adjuvanted bacterin into loin muscle: histopathology and ultrastructure.

Compressive lumbar myelopathy is a recognized iatrogenic complication of injecting water-in-oil vaccines into paravertebral sites of laboratory animals and chickens. Herein, we report the histologic and ultrastructural features of a similar complication in a herd of cattle. Iatrogenic posterior paresis developed over 34 days in 56 of 610 cows (9.2%) following injection of a commercial bacterin 11-34 days earlier into M. longissimus lumborum. The bacterin was composed of inactivated Escherichia coli and Campylobacter fetus ssp. venerealis in a proprietary adjuvant. Tissues were collected for histopathology from 9 affected cattle that died or were euthanized after clinical signs lasting 6-38 days. A range of tissues, including the injection site lesion and lumbar spinal nerve roots, was obtained for ultrastructural examination from a cow with paresis of 31 days duration. There was locally extensive pyogranulomatous myositis with fibrosis and necrosis in right M. longissimus lumborum. Extension of the lesion into the vertebral canal via spinal nerve foramina resulted in focal pyogranulomatous inflammation in epidural fat and in adjacent dura mater. There was axonal degeneration in dorsal, lateral, and ventral columns and chromatolysis of spinal motor neurons in lumbar spinal cord, secondary to compression. A distinctive histologic and ultrastructural feature of pyogranulomata was the presence of osmiophilic material at the center of inflammatory foci, surrounded by macrophages and giant cells that contained intracytoplasmic lipid droplets. Ultrastructural examination of entrapped spinal nerves revealed axonal degeneration and loss of myelinated and unmyelinated fibers, segmental demyelination with remyelination, axonal spheroid formation, and early axonal regeneration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMed2002

Gastrointestinal stromal tumors: an ultrastructural study.

Gastrointestinal stromal tumors (GISTs) represent an enigmatic group of lesions of uncertain phenotype and biologic potential. Although earlier studies suggested smooth muscle cells, schwann cells, or neuronal differentiation, more recent evidence indicates that these tumors show phenotypic features that are similar to the interstitial cells of Cajal. Recently, investigators have begun to evaluate these lesions in a site-specific manner and have found that, in addition to morphologic differences between them, their biologic behavior also appears to be linked to their anatomic location. Many of these studies have emphasized the histologic and immunophenotypic features of GISTs in relation to their sites of origin, however, their site-specific ultrastructural characteristics have received little attention in the literature. In this study, we evaluated 34 GISTs (15 gastric, 12 small intestinal, 4 colonic, and 3 omental) for a variety of ultrastructural features in an effort to identify site-specific similarities and differences. Tumors predominantly composed of epithelioid cells were more commonly seen in gastric (60%) and omental (67%) tumors than in those of the small intestine (33%) and colon (0%). Cytoplasmic filaments and intercellular junctions were commonly seen in tumors from all locations, the filaments frequently forming paranuclear aggregates in the epithelioid cells. Tumors from all sites were composed of cells with surface filopodia and interdigitating cell processes, but in tumors of the stomach and omentum the filopodia were usually short and minimally intertwined, whereas those of small and large intestinal GISTs were characteristically long and complex. Basal lamina, though poorly formed, was present only in tumors of gastric and omental origin (13% and 67%, respectively). Pinocytotic vesicles were also seen in tumors from these sites (33% of gastric tumors and 67% of omental lesions) as well as those of the small intestine (17%) and the colon (25%). None of the gastric or omental tumors had microtubules; they were, however, seen in small intestinal (33%) and colonic (25%) stromal tumors. Skenoid fibers were seen in 33% of small intestinal GISTs and 1 metastatic gastric GIST. Overall, gastric and omental tumors have better developed features of myogenic differentiation and have blunt filopodia and minimally intertwined cell processes. Indeed, these 2 groups are indistinguishable ultrastructurally, raising the possibility that the genesis of omental GISTs is similar to that of gastric stromal tumors. Small intestinal stromal tumors have characteristic interdigitating cell processes and numerous elongate filopodia-like structures harboring intercellular junctions as well as microtubules and extracellular skenoid fibers. The constituent cells in colonic stromal tumors, while more reminiscent of small intestinal stromal, were frequently more primitive in appearance. In conclusion, GISTs from different anatomic locations share many overlapping ultrastructural characteristics; however, a few features are distinctive. It is hoped that these findings will aid in their recognition and contribute to the classification of this heterogeneous group of neoplasms.

Biomarkers, Tumor↗
PubMed2005

Keratin-positive Ewing's sarcoma: an ultrastructural study of 12 cases.

Ewing's sarcoma/primitive neuroectodermal tumor (EWS/PNET) is an aggressive neoplasm of bone and soft tissue. Histologically, it is characterized by the presence of small round blue cells, which usually express MIC-2 and FLI-1 immunohistochemically. The most specific feature for diagnosis, however, is cytogenetic or molecular evidence of a consistent abnormality, the t(11;22)(q24;q12), or variants thereof. The immunohistochemical expression of keratins in a significant proportion of these cases has been highlighted in several recent studies. The ultrastructural features of these keratin-positive tumors have not, however, been characterized in detail. In this study we analyzed the ultrastructural features of 12 well-documented EWS/PNETs that stained strongly for pankeratin by immunohistochemistry. Ultrastructurally, the tumor cells contained a few organelles, which included a small number of mitochondria, poorly developed Golgi complexes, free ribosomes, and inconspicuous rough-endoplasmic reticulum. Rudimentary cell junctions were seen in 2 tumors while prominent junctions were observed in the remaining 10. Five tumors contained intracytoplasmic filaments, and definite tonofibrils were identified in 2. Well-developed basal lamina around tumor cells were also demonstrated in 2 tumors. Follow-up information was available for all cases. Seven patients died of disease, 2 are alive with disease, and 3 have no current evidence of disease. The cohort includes 5 patients with a type-1 translocation, which has been associated with a better prognosis in some studies; 4 of these patients have died of their disease, and 1 is alive with recurrent disease. This study shows that keratin-positive EWS/PNETs have evidence of epithelial differentiation ultrastructurally, and may possibly represent a more aggressive subset of the EWS/PNET group of tumors.

Adolescent↗
PubMed1995

Ultrastructural study of proliferating cells with an improved immunocytochemical detection of DNA-incorporated bromodeoxyuridine.

We designed an improved method to observe proliferating cells with well-preserved ultrastructure. After IP injection of bromodeoxyuridine (BrdU) into rats, the pituitaries were fixed in 4% paraformaldehyde with 0.05% or 0.2% glutaraldehyde and post-fixed with ferrocyanide-reduced osmium. They were embedded in LR White and polymerized by heat. BrdU incorporated into DNA was detected with a commercial anti-BrdU monoclonal antibody (MAb) by the immunogold or the immunogold-silver staining method. Using these methods, proliferating cells labeled by BrdU were observed with well-preserved ultrastructure. By light microscopy, the number of labeled cells was almost the same regardless of the fixative used. By electron microscopy, localization of gold particles that indicate incorporated BrdU varied according to the cells and was mainly observed in two patterns, one in which gold particles were localized in condensed chromatin scattered in the nucleus and the other in which gold particles were dispersed evenly all over the nucleus. These results showed that with our improved method fine ultrastructure and good immunoreactivity of BrdU can be obtained in proliferating cells. We consider that this method is very useful for ultrastructural study of cell proliferation and differentiation.

Animals↗
PubMed2001

The effects of the pre-treatment of intravenous nimodipine on Na(+)-K+/Mg+2 ATPase, Ca+2/Mg+2 ATPase, lipid peroxidation and early ultrastructural findings following middle cerebral artery occlusion in the rat.

Excessive calcium influx has been implicated in the pathophysiology of ischemic cerebral damage. The effects of nimodipine, a calcium antagonist, on the Na(+)-K+/MG+2 ATPase activity, Ca+2/Mg+2 ATPase, lipid peroxidation, and early ultrastructural findings were examined at the acute stage of ischemia in the rat brain. Ischemia was produced by permanent unilateral occlusion of the middle cerebral artery. In Group I, the rats which had no ischemia and not received medication were used for determining Na(+)-K+/Mg+2 ATPase, Ca+2/Mg+2 ATPase, the extent of lipid peroxidation by measuring the malondialdehyde content and normal ultrastructural findings. In Group II, the rats which had only subtemporal craniectomy without occlusion and received saline solution were used for determining the effect of the surgical procedure on the biochemical indices and ultrastructural findings. In Group III, the rats received saline solution following the occlusion in the same amount of nimodipine and in the same duration as used in Group IV. In Group IV, nimodipine pre-treatment 15 min before occlusion (microgram kg-1 min-1 over a 10 min period) was applied i.v. Na(+)-K+/Mg+2 ATPase and Ca+2/Mg+2 ATPase activities decreased significantly and promptly as early as 10 min and remained at a lower level than the contralateral hemisphere in the same group and at the normal level in Group I. Nimodipine pre-treatment immediately attenuated the inactivation of Na(+)-K+/Mg+2 ATPase (p < 0.05) but there was no change on Ca+2/Mg+2 ATPase activity (p < 0.05). Malondialdehyde content increased significantly in Group III following ischemia as early as 30 min. Nimodipine pre-treatment decreased the malondialdehyde level in Group IV (p < 0.05). This study supports the possibility that nimodipine pre-treatment effects the membrane stabilizing properties via inhibiting the lipid peroxidation and subsequently restoring some membrane bound and lipid dependent enzymes' activity such as Na(+)-K+/Mg+2 ATPase and the ultrastructural findings.

Animals↗
PubMed2003

Ultrastructural study shows morphologic features of apoptosis and para-apoptosis in megakaryocytes from patients with idiopathic thrombocytopenic purpura.

To investigate whether altered megakaryocyte morphology contributes to reduced platelet production in idiopathic thrombocytopenic purpura (ITP), ultrastructural analysis of megakaryocytes was performed in 11 ITP patients. Ultrastructural abnormalities compatible with (para-)apoptosis were present in 78% +/- 14% of ITP megakaryocytes, which could be reversed by in vivo treatment with prednisone and intravenous immunoglobulin. Immunohistochemistry of bone marrow biopsies of ITP patients with extensive apoptosis showed an increased number of megakaryocytes with activated caspase-3 compared with normal (28% +/- 4% versus 0%). No difference, however, was observed in the number of bone marrow megakaryocyte colony-forming units (ITP, 118 +/- 93/105 bone marrow cells; versus controls, 128 +/- 101/105 bone marrow cells; P =.7). To demonstrate that circulating antibodies might affect megakaryocytes, suspension cultures of CD34+ cells were performed with ITP or normal plasma. Morphology compatible with (para-)apoptosis could be induced in cultured megakaryocytes with ITP plasma (2 of 10 samples positive for antiplatelet autoantibodies). Finally, the plasma glycocalicin index, a parameter of platelet and megakaryocyte destruction, was increased in ITP (57 +/- 70 versus 0.7 +/- 0.2; P =.009) and correlated with the proportion of megakaryocytes showing (para-) apoptotic ultrastructure (P =.02; r = 0.7). In conclusion, most ITP megakaryocytes show ultrastructural features of (para-) apoptosis, probably due to action of factors present in ITP plasma.

Adult↗
PubMed1980

The effects of spectinomycin and ethidium bromide on the synthesis of organelle rRNA and on ultrastructure in Ochromonas danica.

The effects of 24-h exposure to spectinomycin (100 microgram/ml) and ethidium bromide (1 microgram/ml) on the accumulation of chloroplast and mitochondrial rRNAs and on organelle ultrastructure were studied in greening cells of Ochromonas danica. Cells treated with ethidium bromide for 24 h divide at the same rate as controls but contain less than one third the normal amount of mitochondrial rRNA. Ultrastructural observations showed that these cells contain only 10% the number of mitochondrial ribosomes found in controls as well as fewer mitochondrial cristae. Ethidium bromide has no effect on chloroplast ultrastructure in Ochromonas. Greening cells treated with spectinomycin grow at close to control rates but contain 30-40% less chloroplast rRNA than do controls. Electron microscopy showed that spectinomycin disrupts the organization of chloroplast membranes and reduces the number of chloroplast ribosomes by 30%. Under these conditions, spectinomycin has no effect on mitochondrial rRNA or ultrastructure. Since spectinomycin is a specific inhibitor of translation on 70S ribosomes, these results are consistent with the possibility that at least some chloroplast ribosomal proteins are synthesized in the chloroplast of Ochromonas.

Cell Division↗