Stages Of Disintegration Research Articles

Invasion and destruction of mucosal plasma cells by Tropheryma whippelii

Whipple's disease is a poorly understood systemic disorder associated with the bacillus, Tropheryma whippelii. An early stage of Whipple's disease is studied by using electron microscopy (ELMI) and immunohistochemistry. The diagnosis was confirmed by polymerase chain reaction-amplification and sequencing of the 16S ribosomalRNA of the bacterium. By using ELMI, Tropheryma whippelii was found in plasma cells and macrophages in the jejunal mucosa. The immunoglobulin (Ig)A-positive plasma cells were focally destructed and their number significantly reduced. However, the bacilli in the plasma cells were morphologically intact. In contrast, the macrophages showed no signs of cell destruction, but contained bacilli in various stages of disintegration. A cytopathic effect of Tropheryma whippelii to IgA plasma cells may be the reason for the commonly found plasma cell reduction in the small intestine mucosa and an important pathogenic mechanism contributing to the evasion of the bacilli from local immune response.

Transmission electron microscopic observations of acrosome and head abnormalities in impala (<i>Aepyceros melampus</i>) sperm from the Kruger National Park

Sperm morphological features play an important role in semen evaluation. Exposure to a variety of chemical compounds, especially environmental endocrine disrupters, elicit abnormalities in sperm of certain species. Baseline data on ultrastructure of normal sperm as well as abnormalities observed concomitantly, are required before causal links between such substances and abnormalities can be established. Live spermatozoa were collected from the cauda epididymis of 64 impala rams in the Kruger National Park and studied by transmission electron microscopy to document normal sperm features and abnormalities. The following abnormalities of the acrosome and sperm head were documented from micrographs: Loose acrosome in various stages of disintegration, lip forming of the acrosome; bizarre head, crater defect, poor condensation of the nucleus and the Dag defect. The observed abnormalities were very similar to those reported for other members of the Bovidae. Different forms of a hollow sphere, formed by the nucleus and covered by an abnormal acrosome have not previously been described for other species.

A basic study on the solid-state nitriding of aluminum by mechanical alloying using a planetary ball mill

Nitrogen dispersed amorphous aluminum powders were synthesized by high energy grinding using a planetary ball mill under N 2 atmosphere at room temperature. The modes of amorphization and recrystallization during the grinding were investigated by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The grinding process can be classified into three stages, i.e. agglomeration, disintegration and homogenization. During the disintegration stage, an amorphous phase was formed and N 2 was supposed to diffuse into the aluminum. Recrystallization of N 2 dispersed amorphous aluminum powders was also studied. By annealing the final ground product in air and in vacuum at 1373 K for 3600 s, the particles were recrystallized to AIN/AI 2O 3 and AIN/Al composite, respectively.

Female genital schistosomiasis (FGS): relationship between gynecological and histopathological findings

Schistosomiasis of the lower female reproductive tract manifests itself in broad spectrum of clinical features. However, clinical and histopathological findings have never been studied in a synoptic manner. Based on the assumption that any type of pathology present in the female reproductive tract is the expression of a complex pathophysiological reaction towards eggs sequestered in the genital tissues, we decided to analyze colposcopic and histopathological findings in a comprehensive manner. Thirty-three women in Malawi with urinary and genital schistosomiasis were examined parasitologically and gynecologically. A thorough colposcopic examination with photodocumentation was performed and biopsies were taken from the cervix, the vagina and/or the vulva for histological sectioning and immunohistochemistry. The predominant colposcopic findings were sandy patches on the cervical surface similar to those seen in the bladder and polypous/papillomatous tumors with irregular surface on the vaginal wall and in the vulvar area. The histopathological sections of sandy-patch-like lesions demonstrated only a small cellular reaction around S. haematobium eggs in various stages of disintegration. In contrast, in the case of polyps the histology revealed a more pronounced immunological reaction characterized by a heavy cellular infiltrate. One case of invasive squamous cell carcinoma of the cervix was diagnosed. We conclude that colposcopy is a useful tool in the detection of FGS related pathology in the lower female reproductive tract and that the synoptic assessment of surface and of corresponding histological sections helped to understand the pathophysiology of S. haematobium associated disease in genital tissue.

Ultrastructural morphological changes are not characteristic of apoptotic cell death following focal cerebral ischaemia in the rat

We have used a permanent middle cerebral artery occlusion (MCAO) model in the rat to ascertain if the DNA fragmentation seen in nuclei, shows the characteristic ultrastructural features of apoptosis. Results from light and electron microscopic studies were compared with those from a neonatal model of excitotoxic cell death in which classical apoptotic changes were seen in a subpopulation of cells. At 6 and 24 h following occlusion, cells were either swollen or dark and shrunken showing a disordered cytosol. At 24 h survival a high number of cells in the lesion core and lesion border showed internucleosomal DNA breaks, which were detected in sections using terminal dUTP nick-end-labelling (TUNEL). Electron microscopy of cells with TUNEL positive spherical structures of condensed chromatin in the lesion core showed an advanced stage of cellular disintegration as opposed to an apoptotic morphology of a subpopulation of cells with chromatin condensation in the cortex and mammillary body of N-methyl- d-aspartate (NMDA) treated neonatal rats. We conclude that in focal cerebral ischaemia internucleosomal DNA fragmentation associated with chromatin condensation is a late consequence of ischaemic cell death rather than a hallmark of apoptosis.

Inhibition of the degradation of chloroplast membranes during senescence in nuclear ‘stay green’ mutants of soybean

Near‐isogenic lines of soybean (Glycine max [L.] Merr.) cv. Clark carrying nuclear ‘stay green’ genes were examined to determine the effects of these genes on the breakdown of thylakoid membranes during senescence. In order to accelerate their senescence, mature leaves were excised and incubated in darkness for 7 days. The homozygous combination of the recessive alleles d1 and d2 (at two different nuclear loci), with or without G (a dominant allele in another locus that causes green seed coat) inhibited the loss of chlorophyll and thylakoid proteins during senescence. Electron micrographs of leaves of cv. Clark during the yellowing process showed chloroplasts in various stages of disintegration; their thylakoid network was disrupted and abundant osmiophilic globuli formed. These senescent leaves also showed evident signs of deterioration of the plasma membrane, including discontinuities, invaginations and membrane ‘whorls’. In contrast, leaves carrying d1d1d2d2 and GGd1d1d2d2 did not show signs of plasma membrane degradation, and their chloroplasts appeared intact, with a continuous, unbroken thylakoid network and tightly stacked grana.Exogenous applications of abscisic acid (1 and 10 μM), methyl jasmonate (10 μM) or ethylene (1 and 10 μl]−1) accelerated chlorophyll degradation in cv. Clark, but had no appreciable effect in d1d1d2d2 and GGd1d1d2d2, which indicates that their pheno‐types are not due to a deficiency in any of these hormones. The nuclear ‘stay green’ genotypes d1d1d2d2 and GGd1d1d2d2 exhibit a general incompetence for the degradation of chloroplast membranes and, thus, they may constitute useful tools in the study of the biochemistry and regulation of leaf senescence.

The Malagasy Rift, a chasm in the Tethyan margin of Gondwana

In Permian and Triassic times plate collision and consumption along the Pacific margin of Gondwana contrasted with rifting and extensional conditions along the Tethyan rim. The latter caused the development of two major rifts, the Westralian Trough between Australia and Greater India and the Malagasy Trough between Africa-Arabia and Madagascar-India. Formation of the Malagasy Trough commenced in the Early Permain. It is evidenced by rift structures which extend from eastern Africa and Madagascar to Oman and possibly beyond. In Tanzania these early intracratonic rifts produced the mega-sequence of the Karoo Super Group. This succession which was initiated by Late Palaeozoic glacial deposits is almost entirely of terrestrial origin. However, in Madagascar and to the north thereof, marine Tethyan faunas were quick to take possession of the Malagasy Trough after deglaciation, indicating an open and unrestricted connection with the Tethys. In the same direction in which marine conditions increased, post-glacial coal deposition diminished and gave way to mildly evaporitic conditions. Various stages of rifting and disintegration are reflected by depositional sequences of east African and Madagascar Karoo Basins. These Late Palaeozoic and Triassic tectonic movements can be matched at least in parts with tectonic events in the Tethyan realm. Evidence for the development of both Malagasy and Westralian Troughs place important constraints on the positioning of continental blocks and the palaeogeography of the central Tethys in Permo-Triassic times.

Temporal Aspects of Sperm Transfer and Spermatophore Condition in Mexican Rice Borers (Lepidoptera: Pyralidae)

Sperm transfer and spermatophore disintegration in females and duplex refilling in males of the Mexican rice borer, Eoreuma loftini (Dyar), were examined by freezing moths at time intervals after mating. Eupyrene sperm location and spermatophore condition in female moths changed with time after mating. Sperm transferred from the spermatophore to the spermatheca between 6 and 8 h after mating. Spermatophores passed through several stages of disintegration and were completely disintegrated after 72 to 96 h. Stages of spermatophore disintegration are described and can be used to estimate time since females have mated. Numbers of sperm bundles in male duplexes increased with increasing time after mating but were too variable to be of practical use in assessing mating status. The best indicator of male mating status was duplex condition (color). Duplex condition can be used to determine mating status for ≈6h after mating, although estimates using this criterion will be slight underestimates of actual mating activity.

Ultrastructural changes in rat epididymides induced by cowpeas.

The ultrastructure of tubular inclusions of caput and cauda epididymides were studied in rats that were fed only cowpeas from weaning (20-22 days old) to 130 days. The results showed significant (p < .001) fall in body weight and testicular, caput, and cauda epididymal weights in the cowpea-fed animals. Although the walls of the epididymides remained intact, the lumina of both segments showed cellular inclusions of various types amid sperm clumps. Unlike controls, where sperm flagella and headpieces were free-floating in lumina of both segments of epididymides, the experimental tubules showed cytoplasmic droplets containing trapped flagella at various stages of disintegration. Other inclusions included multilobular giant cells, lymphocytes, and membrane-bound amorphous bodies. It is proposed that these changes might be due to an altered immune response induced by lectins, one of the antinutritional factors found in cowpeas, which causes epididymal dysfunction and possibly renders these animals infertile.

Time Prediction of a Rock Fall in the Carnic Alps

Abstract Based on an extensive field study and on the long-term monitoring of the kinematics of a toppling rock tower standing on a slope edge, a forecast of the time of its failure is presented. This is derived from a consideration of both present static equilibrium of the rock block including its kinematics and phenomenological characteristics and also the stage of disintegration of the block as part of the processes leading to rock fall.

Kinetics of MoSi2 pest during low-temperature oxidation

The kinetics of MoSi2 pest, caused by oxidation in air, has been studied. Experimental results indicated that pest disintegration occurred at temperatures between 375 and 500 °C. The volumes of test samples increased with oxidation duration. Analysis of change in sample volume versus oxidation duration revealed that the pest disintegration consisted of two stages, namely nucleation (or incubation) and growth. The onset of the growth stage depended on the test temperature. More importantly, changes in sample volume were found to obey a linear relationship with time during the growth stage. Equations were formulated to demonstrate that the growth kinetics of pest disintegration was proportional to the rates of change in sample volume. The rates of volume change during MoSi2 pest were calculated to be 4.9 × 10−6, 2.8 × 10−5, 3.7 × 10−5, and 5.4 × 10−5 cm3/s at 375, 400, 425, and 450 °C, respectively; the growth kinetics increased with oxidation temperature. The activation energy for the growth stage of pest disintegration was determined to be 27.6 kcal/mole, which agrees well with the activation energy for the low-temperature oxidation of MoSi2.

The lysosomal system in neuronal cell death: a review.

The lysosomal system has often been considered a prominent morphologic marker of distressed or dying neurons. Lysosomes or their constituent hydrolases have been viewed in different neuropathologic states as either initiators and direct agents of cell death, agents of cellular repair and recompensation, effectors of end-stage cellular dissolution, or autolytic scavengers of cellular debris. Limited data and limitations of methodology often do not allow these potential roles to be discriminated. In all forms of neurodegeneration, it may be presumed that lysosomes ultimately rupture and release various hydrolases that promote cell autolysis during the final stages of cellular disintegration. Beyond this perhaps universal contribution to cell death, the degree to which the lysosomal system may be involved in neurodegenerative states varies considerably. In many conditions, morphologic evidence for activation of the lysosomal system is minimal or undetectable. In other cases, lysosomal activation is evident only when other morphologic signs of cell injury are also present. This level of participation may be viewed as either an attempt by the neuron to compensate for or repair the injury or a late-stage event leading to cell dissolution. The early involvement of the lysosomal system in neurodegeneration occurs most commonly in the form of intraneuronal accumulations of abnormal storage profiles or residual bodies (tertiary lysosomes). Very often the lysosomal involvement can be traced to a primary defect or dysfunction of lysosomal components or to accelerated or abnormal membrane breakdown that leads to the buildup of modified digestion-resistant substrates within lysosomes. Because they are often striking, changes in the lysosomal system are a sensitive morphologic indicator of certain types of metabolic distress; however, whether they reflect a salutary response of a compromised neuron or a mechanism to promote cell death and removal of debris from the brain remains to be established for most conditions. Factors that may influence the lysosomal response during lethal neuronal injury include species differences, stage of neuronal development, duration of injury and pace of cell death. The lysosomal system may be more closely coupled to certain forms of neuronal cell death in lower vertebrate or invertebrate systems than in mammalian systems.

Morphological and calorimetric studies on the Amorphization Process of Rod-Milled Al50Zr50 Alloy Powders

Amorphous Al50Zr50 alloy powders have been prepared by rod-milling technique using mechanical alloying (MA) method. The amorphization and crystallization processes of the alloyed powders were followed by optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). The results have shown that the formation of amorphous Al50Zr50 alloy powders occurs through three stages, agglomeration, disintegration, and homogenization. At the disintegration stage, the alloyed powders contain many fine layers of Al and Zr. An amorphous phase has been formed at about 880 K as a result of heating these layered particles in a thermal analyzer. The crystalline-to-amorphous transformation at this stage of milling is attributed to a thermally assisted solid-state amorphizing reaction. The present study corroborates the similarity of the amorphization process through the MA with the solid-state interdiffusion reaction in multilayered thin films. The amorphization temperature, Ta, and the activation energy of amorphization, Ea, are 675 and 156 kJ/mol, respectively. In addition, the enthalpy change of amorphization, ΔHa, was evaluated to be -3.5 kJ/mol. On the other hand, the crystallization temperature, Tx, and enthalpy change of crystallization, ΔHx, were 1000 K and −68 kJ/mol, respectively.

Membranous cytoplasmic bodies in the lateral wall of the cat cochlea.

Membranous cytoplasmic bodies (MCBs) were observed both in the intermediate cells of the stria vascularis and in the fibrocytes of the spiral ligament in normal cats. The MCBs in the intermediate cells were round or ovoid, ranged from 1 to 5 microns in diameter, and consisted of 2 to 40 or more layers disposed concentrically about a core. The core was composed of not only cytoplasm but also of mitochondria in various stages of disintegration, empty vacuoles, and many kinds of dense bodies similar to lysosomes. The MCBs in the fibrocytes were similar to those in the intermediate cells, but they were a little smaller in diameter and consisted of fewer than 10 layers. Both in the intermediate cells and in the fibrocytes, MCBs seem to have a phagocytic function.

Behavior of germinal micronuclei under control of the somatic macronucleus during conjugation in Paramecium caudatum

In conjugating pairs of Paramecium caudatum, the micronuclear events occur synchronously in both members of the pair. To find out whether micronuclear behavior is controlled by the somatic macronucleus or by the germinal micronucleus, and whether or not synchronization of micronuclear behavior is due to intercellular communication between conjugating cells, the behavior of the micronucleus was examined after removal of the macronuclei from either or both cells of a mating pair at various stages of conjugation. When macronuclei were removed from both cells of a pair, micronuclear development was arrested 1 to 1.5 hr after macronuclear removal. When the macronucleus of a micronucleate cell mating with an amicronucleate cell was removed later than 3 to 3.5 hr of conjugation, that is, an early stage of meiotic prophase of the micronucleus, micronuclear events occurred normally in the operated cell. These results suggest that most micronuclear events are under the control of the macronucleus and that the gene products provided by the macronucleus are transferable between mating cells. One such product is required for induction of micronuclear division and is provided just before metaphase of the first meiotic division of the micronucleus. This factor is effective at a lower concentration in the cytoplasm and/or is more transferable between mating cells than the factors required for other stages. This factor, which seems to be present at least until the stage of micronuclear disintegration, is able to induce repeated micronuclear division as long as it remains active. The factor can act on a micronucleus which has not passed through a meiotic prophase. Moreover, the results suggest the existence of a second factor which is provided by the macronucleus after the first meiotic division that inhibits further micronuclear division.

Does chloroquine, an antimalarial drug, affect autophagy in Tetrahymena pyriformis?

The effect of chloroquine (CQ) on autophagy was studied in starved Tetrahymena pyriformis. When a proliferating Tetrahymena culture is transferred to a starvation medium, autophagy commences although cells most advanced in the cell cycle will divide. The drug was added to 1-h starved cells at different pH values because CQ affects pH dependently. The CQ concentration blocking all cell divisions was determined as the lowest toxic, but sublethal, concentration. Hence, the highest tolerated concentrations at pH 6.8, 7.1, and 7.7 were 1.0, 0.3, and 0.03 mM CQ, respectively. Lower CQ concentrations had a dose-dependent effect on cell increment and higher concentrations induced cell mortality. Rates of cell motility and decreases in cell volume were affected by the drug, while the capacity for endocytosis was unaffected in low concentrations but affected dose dependently in high concentrations. Light microscopically, all drug-treated cells contained small refractive bodies, but in toxic concentrations they also contained conspicuously large vacuoles. After 1 h and 4 h in CQ, fine structure analysis showed autophagosomes with electron-dense material in cells in tolerated concentrations and of enlarged size, but decreased number, in toxic concentrations. The contents of autophagosomes revealed cell organelles in different stages of disintegration. The conclusion is that the drug enhances autophagy in Tetrahymena in a pH-, dose-, and time-dependent manner.

Nonoccluded, cytoplasmic virus particles and rickettsia-like organisms in testes and spermathecae of Diabrotica virgifera

An ultrastructural study was conducted on the testes and spermateca of adult Diabrotica virgifera virgifera that exhibited a high incidence of abnormal sperm. The cytoplasm of spermatocyst cells was found to contain large masses of 24 to 26-nm virus particles assembled in loose aggregates or in tightly packed crystalline arrays. Double-tailed and frayed sperm in various stages of disintegration were associated with the spermatocyst cells. Similar virus particles in crystalline arrays were found in spermathecal epithelial cells and in muscle cells associated with the spermatheca. The size and appearance of the particles suggest that the virus is a picornavirus. Rickettsia-like organisms (RLO) were abundant in spermatocyst cells in addition to virus particles. These organisms were ca. 0.6 μm in diameter and up to 2.7 μm in length and were found either singly or in various-sized aggregates. The RLOs were each surrounded by a double unit membrane and colonies composed of several individuals were enclosed within a cellular vacuolar membrane. Although the virus appears to be involved in the production of abnormal sperm, the RLOs appear to act as harmless symbionts as they were abundant in spermatocyst cells that were free of damaged sperm and were present in other tissues.

The Nature of Hyaline (Eosinophilic) Globules and Vascular Slits of Kaposiʼs Sarcoma

Ultrastructural studies of Kaposi's sarcoma (KS) from skin biopsies of 24 patients (eight with acquired immunodeficiency syndrome (AIDS) and 16 without) were performed to delineate the nature of hyaline globules and vascular slits. These structures have been regarded as one of the important criteria for the recognition of KS under light microscopy. Histochemical and immunochemical studies were also performed to correlate with the electron microscopic (EM) observations. The most remarkable EM findings of KS were the intracytoplasmic lumen formation and erythrophagocytic activities of the neoplastic cells, particularly in the mature nodular, or neoplastic stage. The spindle-shaped or ovoid neoplastic cells frequently contained one to several intact and fragmented red blood cells. The intracellular and extravasated erythrocytes were often arranged in single files, giving these vascular slits an elongated appearance on longitudinal sections. The phagocytic activities of the neoplastic cells were demonstrated by the presence of membrane-bound lysosomes containing phagocytized erythrocytes and their partially digested forms (erythrophagosomes) adjacent to pinocytotic vesicles, prominent rough endoplasmic reticulum, and Golgi apparatus, as well as scattered, small, membrane-bound lysosomal granules, some of which were attached to the erythrophagosomes. The erythrophagosomes underwent various stages of disintegration. The partially digested red cells varied from 0.4 to 10 microns in diameter. The results of histochemical and immunochemical findings also strongly suggested that erythrophagosomes were most likely the hyaline globules (bodies) seen in light microscopy. The exact mechanism of erythrophagocytosis is uncertain. However, its consequences, erythrophagosomes, and intracytoplasmic lumen formation, particularly in the nodular or neoplastic stage in patients with and without AIDS, are among the important histologic features of KS.

Enzymatically active lysosomal proteases are associated with amyloid deposits in Alzheimer brain.

The formation of beta-amyloid in the brains of individuals with Alzheimer disease requires the proteolytic cleavage of a membrane-associated precursor protein. The proteases that may be involved in this process have not yet been identified. Cathepsins are normally intracellular proteolytic enzymes associated with lysosomes; however, when sections from Alzheimer brains were stained by antisera to cathepsin D and cathepsin B, high levels of immunoreactivity were also detected in senile plaques. Extracellular sites of cathepsin immunoreactivity were not seen in control brains from age-matched individuals without neurologic disease or from patients with Huntington disease or Parkinson disease. In situ enzyme histochemistry of cathepsin D and cathepsin B on sections of neocortex using synthetic peptides and protein substrates showed that senile plaques contained the highest levels of enzymatically active cathepsin. At the ultrastructural level, cathepsin immunoreactivity in senile plaques was localized principally to lysosomal dense bodies and lipofuscin granules, which were extracellular. Similar structures were abundant in degenerating neurons of Alzheimer neocortex, and cathepsin-laden neuronal perikarya in various stages of disintegration could be seen within some senile plaques. The high levels of enzymatically competent lysosomal proteases abnormally localized in senile plaques represent evidence for candidate enzymes that may mediate the proteolytic formation of amyloid. We propose that amyloid precursor protein within senile plaques is processed by lysosomal proteases principally derived from degenerating neurons. Escape of cathepsins from the stringently regulated intracellular milieu provides a basis for an abnormal sequence of proteolytic cleavages of accumulating amyloid precursor protein.

The Permo-Carboniferous Dwyka Formation of Southern Africa: Deposition by a predominantly subpolar marine ice sheet

The 800-m thick glacigene Dwyka Formation was deposited along the northern margin of the Permo-Carboniferous Dwyka Basin which covered an area of approximately 2 × 10 6 km 2 in southwestern Gondwana. The palaeogeographic setting, geochemical data of the mudrocks and diamictites, and the palaeontology indicate marine conditions during sedimentation. Ice lobes from spreading centres in the north, east and south coalesced in the basin to form an extensive ice cover from the Westphalian to the late Sakmarian. Lodgement, rain-out and subaqueous debris-flow diamictons, subaqueous and subglacial melt-water sands, suspended mud, and turbidity current sands and silts accumulated in the Dwyka Basin. Sedimentation started on the continental shelf during a grounded ice sheet stage (predominantly lodgement processes), then a floating ice stage (predominantly debris rain-out), and finally an ice sheet disintegration stage (debris rain-out, sand fall-out and suspension settling of mud). The palaeogeographic setting, presence of marine conditions in the basin and the scale of glaciation indicate deposition from a predominantly mid-latitudinal marine ice sheet. The overall characteristics of the glacial sequence are neither typical of a polar nor a temperate setting and for such ancient glaciations a subpolar setting with the presence of unstable ice shelves is suggested.