Heart morphological changes in rats placed in a crowded environment

A group of rats were stressed by placing them in a crowded environment. Examination of the hearts showed the following anatomic changes: (1) increased weight; (2) occlusion of capillaries by platelet thrombi; (3) endothelial swelling of capillaries; and (4) swelling and deformity of mitochondria.

Transport and oxidation of choline by liver mitochondria

1. Rapid choline oxidation and the onset of P(i)-induced swelling by liver mitochondria, incubated in a sucrose medium at or above pH7.0, required the addition of both P(i) and an uncoupling agent. Below pH7.0, P(i) alone was required for rapid choline oxidation and swelling. 2. Choline oxidation was inhibited by each of several reagents that also inhibited P(i)-induced swelling under similar conditions of incubation, including EGTA, mersalyl, Mg(2+), the Ca(2+)-ionophore A23187, rotenone and nupercaine. None of these reagents had any significant effect on the rate of choline oxidation by sonicated mitochondria. There was therefore a close correlation between the conditions required for rapid choline oxidation and for P(i)-induced swelling to occur, suggesting that in the absence of mitochondrial swelling the rate of choline oxidation is regulated by the rate of choline transport across the mitochondrial membrane. 3. Respiratory-chain inhibitors, uncoupling agents (at pH6.5) and ionophore A23187 caused a loss of endogenous Ca(2+) from mitochondria, whereas nupercaine and Mg(2+) had no significant effect on the Ca(2+) content. Inhibition of choline oxidation and mitochondrial swelling by ionophore A23187 was reversed by adding Ca(2+), but not by Mg(2+). It is concluded that added P(i) promotes the Ca(2+)-dependent activation of mitochondrial membrane phospholipase activity in respiring mitochondria, causing an increase in the permeability of the mitochondrial inner membrane to choline and therefore enabling rapid choline oxidation to occur. Nupercaine and Mg(2+) appear to block choline oxidation and swelling by inhibiting phospholipase activity. 4. Choline was oxidized slowly by tightly coupled mitochondria largely depleted of their endogenous adenine nucleotides, suggesting that these compounds are not directly concerned in the regulation of choline oxidation. 5. The results are discussed in relation to the possible mechanism of choline transport across the mitochondrial membrane in vivo and the influence of this process on the pathways of choline metabolism in the liver.

Ultrastructural studies of cell-virus interaction in reptilian cell lines. IV. Effects of chloramphenicol and ethidium bromide on VSW cell mitochondria and associated virions

Structural effects of chloramphenicol (CAP) and ethidium bromide (EB) on VSW cell mitochondria and intramitochondrial virions (IMV) have been studied on a comparative basis by thin-section electron microscopy. CAP-treated cells show a wide variety of mitochondrial alterations, frequently involving swelling of the organelle and loss of cristae orientation. IMV are generally severely disrupted, particularly in peripheral regions. In such configurations, strand-like material radiates in a spokelike fashion from the shell zone to adjacent cristae-matrix area. EB-treated cells also display considerable mitochondrial distortion evidenced primarily by the formation of small, localized multimembrane regions. IMV exposed to EB, however, are less structurally damaged than CAP-treated ones. The relative incidence of IMV production is enhanced approximately fourfold in EB-treated cells compared to CAP-treated ones, suggesting that virion synthesis may be under nuclear, rather than mitochondrial, control.

Experimental spongy degeneration in calves

Experimental reproduction and ultrastructural findings of spongy degeneration of the central nervous system of hyperammonemic calves are described. Hyperammonemia was produced by intravenous infusion of ammonium acetate. Histologic findings were stereotyped in all calves and characterized by widespread vacuolation of white and grey matter of the brain spinal cord. Electron microscopy revealed widespread intramyelinic vacuoles, some expansion of extracellular spaces and swollen mitochondria. There were minimal changes in neurons, axons and glia, and little evidence of myelin breakdown. Hyperammonemia may be one of the pathogeneses involved in the CNS spongy degeneration in man and domestic animals effected with hepatocerebral diseases and some hereditary disorders.

Acute tissue response to cerebral ischemia in the gerbil. An ultrastructural study

The Mongolian gerbil, because of the uniqueness of the anatomical features of its circle of Willis, has become an increasingly useful model in the study of cerebrovascular disease. The present work defines acute changes at the ultrastructural level following ischemic insult. The pathomorphological responses include initial astrocytic involvement and, when the degree of insult is increased, a progression of morphological changes is evident in neuronal and other parenchymal elements. Animals with vessels occluded for more than 3 hr without neurological signs suggestive of ischemia exhibited limited perivascular edema. Contralateral changes (perivascular astrocytic) were observed in the basal ganglia at 24 hr in animals with neurological deficit. Astrocytic and basal ganglia susceptibility to ischemia was consistent with previous findings in primate models. An additional association was found in that limited edematous involvement could exist in animals without neurological deficit but neuronal changes were only present in animals with signs of ischemic neurological deficit.

Permeability of the mitochondrial membrane to bicarbonate ions

Osmotic-swelling techniques show that HCO3- enters mitochondria by an electrogenic process, effectively HCO3- uniport, under non-energized conditions. This mode of translocation accounts for previous reports of non-entry of HCO3- in experiments with energy-linked Ca2+ uptake. The effects of HCO3- on mitochondrial respiration are reported and discussed.

Myocardial cell lesions caused by an anabolic hormone

Early changes in the composition of heart muscle cells of the rat caused by an anabolic hormone were investigated by electron microscopy. Mitochondria and myofibrils showed changes similar to those observed in early heart failure: The mitochondria were swollen and elongated. Their matrix was sparse and the cristae were few in number. The myofibrils showed either disintegration and widened and twisted Z-bands or a complete dissolution of the sarcomeric units.

Ultrastructural abnormalities of liver cells in Reye's syndrome

Electon microscopic observations were made on liver biopsy specimens from nine infants and children diagnosed as having Reye's syndrome by clinical, laboratory, and light microscopic criteria. In addition to excessive fat content, mitochondrial abnormalities were the most frequent abnormal finding in the liver. However, no correlation could be established between the severity of mitochondrial changes and clinical or biochemical data, and two patients with low levels of the first two urea cycle enzymes showed only mild mitochondrial abnormalities. Nonspecific or artifactual factors have been suggested to explain the mitochondrial changes. However, the data of this study suggest that most of the reported mitochondrial abnormalities are not artifacts, and that they can be helpful in the ultrastructural diagnosis of Reye's syndrome.

Ultrastructural alterations in ciliary cells exposed to ionizing radiation. A scanning and transmission electron microscopic study

Early effects of ionizing radiation were investigated in an experimental in vitro system using the ciliary cells of the tracheal mucous membrane of the rabbit, irradiated at 30 degrees C and at more than 90% humidity. The changes in physiological activities of the ciliary cells caused by irradiation were continuously registered during the irradiation. The specimens were examined immediately after irradiation electron microscopically. The morphological changes in irradiated material after 10-70 Gy are compared with normal material. After 40-70 Gy, scanning electron microscopy revealed the formation of vesicles on cilia, and club-like protrusions and adhesion of their tips. After 30-70 Gy, a swelling of mitochondrial membranes and cristae was apparent transmission electron microscopically. The membrane alterations caused by irradiation are assumed to disturb the permeability and flow of ATP from the mitochondria, which in turn leads to the recorded changes in the activity of the ciliated cells.

Intraocular axonal swelling produced by partial, immediately retrobulbar ligature of optic nerve

This is the first report of an experimental intraorbital ligature producing papilledema characterized by axonal swelling and accumulation of mitochondria in the lamina retinalis of the optic disc of rhesus monkeys subjected to immediately retrobulbar ligature of a portion of the optic nerve. This is an improved technique for investigating the pathogenesis of papilledema and optic neuropathy.

Studies on cellular recovery from injury. II. Ultrastructural studies on the recovery of the pars convoluta of the proximal tubule of the rate kidney from temporary ischemia

The pars convoluta of the proximal tubule of the rat kidney was studied by light and electron microscopy during the recovery phase from transient ischemia. The left kidney was made ischemic by clamping the aorta just above the left renal artery leaving the blood supply to the right kidney and the intestine intact. The pars convoluta (P1 and P2 segments) of the proximal tubule was examined both immediately after various periods of ischemia (15, 30, 60 and 120 min) and after the same ischemic periods followed by 3, 6, 12 and 24 h of blood reflow (= recovery phase). It was found that ischemia for periods up to 60 min were compatible with cell survival whereas 120 min of ischemia gave rise to irreversible cellular changes. Before regaining a normal conformation during the recovery phase, cells made ischemic for 15 min were characterized by slightly decreased cell height, dispersed nuclear chromatin, mitochondria in orthodox conformation and increased numbers of digestive vacuoles and of lipid droplets (stage A2). Most cells made ischemic for 15 min appeared normal when examined after 24 h of reflow. Cells made ischemic for 30 min were also characterized by stage A2 changes after 3 h of reflow and remained in this stage during all recovery periods studied. Cells made ischemic for 60 min first passed into a stage designated A1 and then later during the recovery phase into stage A2. Stage A1 cells were characterized by decreased height, condensed mitochondria, apparently increased numbers and sizes of secondary lysosomes and slightly dilated rough surfaced endoplasmic reticulum; 120 min of ischemia followed by reflow was not compatible with cell survival. Cells made ischemic for 120 min showed the following alterations denoted as stages C and D: shrunken with pyknotic nuclei, swollen mitochondria with large flocculent densities, and filled with different sized vesicles in the apical portion (stage C). Stage D included cells which had undergone necrosis, i.e., phasma membranes and organelles were fragmented and occurred as debris in the tubule lumens.

Glutaraldehyde fixation for electron microscopy of needle biopsies from human livers

A study including light- and electron microscopy of needle biopsies from normal and fatty human livers fixed by immersion into glutaraldehyde is presented. Four zones which can be detected by light microscopy of toluidine blue stained sections are found: zone 1, the outer one is presumably mechanically damaged. Zone 2 is usually considered to be the most well-preserved region, whereas zones 3 and 4 present increasing swelling of mitochondria, a progressive condensation of microbodies and an increasingly pronounced vesiculation of the smooth endoplasmic reticulum (SER). The alterations observed in zone 3 and 4 are of types which might simulate pathological changes. An increasing irregularity of the outline of the nuclei and a greater accumulation of chromatin along the nuclear membrane is also observed in these two zones. The perimembraneous cytoplasmic ground substance appears to be more dense and the intercellular spaces to be less distinct in the deeper zones in which the path of diffusion of the fixative is long. As regards the penetration into the tissue of glutaraldehyde, normal and steatotic livers were not found to differ. Fixation at 0 degrees C was found to be less effective than fixation at 22 degrees C.

[Cation permeability of liver mitochondrial membranes during Ca+-dependent anoxic damage in vitro]

Ca2+ ions are responsible for impairment of oxidative phosphorylation in rat liver mitochondria under anoxia in vitro. The decrease in this function is due to inhibition of electron transport over respiratory chain and to uncoupling. The increase in membrane permeability for H+, K+ and Na+ was observed on incubation of mitochondria under anoxic condition together with Ca2+. Uncoupling of phosphorylation depends on the increased permeability of the membranes for H+. The increased permeability of membranes for Na+ and K+ under energy liberation and in presence of penetrating anions led to active swelling of organelles and to secondary (osmotic) impairment. Ca2+-activated mitochondrial phospholipase A2 appears to participate in the organelle impairment under anoxia.

Ultrastructural lesions of muscle and immunofluorescent deposits in vessels in Reye's syndrome: a preliminary report of serial muscle biopsies

Thirteen sequential percutaneous skeletal muscle biopsy specimens from 4 patients with Reye's syndrome were studied ultrastructurally and by direct immunofluorescence. Prominent generalized intermyofibrillar edema, mitochondrial disruption, and swelling of vascular endothelium were demonstrated in 2 patients. In all 4 patients there were granular deposits of immunoglobulins G and M in intramuscular vessels, presumably representing antigen-antibody complexes. We postulate that these changes may be pathogenetically important in this syndrome and suggest that muscle biopsy tissue be utilized for further investigation of Reye's syndrome.

Morphologic changes during incubation of renal slices

The progression of ultrastructural changes was studied during various conditions of incubation of rat and mice renal cortex slices. The kidneys were sliced with a Stadie-Riggs microtome and incubated in various media (tris(hydroxymethyl) aminomethane (Tris), Tris-proline, and Hanks), in different oxygenation conditions (O2-CO2, 6 liters per minute; N2, 0.5 liter per minute), at different temperatures (37 degrees C, 23 degrees C.) and different time intervals (0 to 120 minutes). The most conspicious changes appear to involve plasma membranes and mitochondria. Early changes (0 to 30 minutes) are mainly confined to mitochondria cristae and matrix; there is also light swelling of the endoplasmic reticulum. After 30 minutes of incubation, the majority of mitochondria have a condensed form: dense matrix and slight dilation of the cristae. These modifications are more accentuated at 75 minutes and many mitochondria are swollen and contain dense material. The modification of the membrane takes place at 30 minutes by vesiculation and/or a diffuse dilation of brush border and is followed by myelinization. The antiluminal membrane appears less sensitive but the same modification pattern appears after 75 minutes. These changes appear more slowly at 23 degrees C. than at 37 degrees C. Kinetic studies were also carried out confirming findings of various authors; cellular uptake and accumulation of 14C-glycine still take place after 2 hours of incubation. The kidney cortex slicing technique does not seem to be suitable for the study of absorption at the luminal membrane. Furthermore, our observations suggest that the generally accepted ultrastructure of some organelles does not correspond to their appearance in the noramlly functioning state in vivo.

Pyruvate transport in tumour-cell mitochondria

Tumour-cell mitochondria contain a pyruvate-transporting system exhibiting the same general properties as those described in rat liver mitochondria. The Km for net pyruvate uptake in tumour-cell mitochondria is practically similar to that measured in rat liver mitochondria but the V is lower. This difference is also shown by swelling experiments. The possible implication of these observations in the context of lactate accumulation in tumour-cell is discussed.

Pancreatic islets subjected to different concentrations of glucose in vitro. A study with special regard to mitochondrial changes

Isolated pancreatic islets of mice and gerbils were cultured for 6 days at low (2mM) or high (20mM) concentrations of glucose after which they were studied using qualitative and quantitative electron microscopy, histo- and microchemistry, and X-ray microanalysis. Compared with the islets cultured at high glucose, those subjected to low glucose exhibited enhanced succinate dehydrogenase activity, a decreased content of adenosine triphosphate, and an increased volume of B-cell mitochondria which often were rounded or oval.

The protective effect of propranolol on ischemic myocardium: an electron microscopic study

The protective effect of propranolol on ischemic myocardium was studied experimentally and clinically by electron microscope. In an animal experiment, ischemic changes were produced in the posterior papillary muscle of the rabbit following 3, 15, 30 minutes of occlusion of the circumflex coronary artery. Propranolol (0.25 mg/kg) was injected into the left atrial cavity before occlusion of the artery. The posterior papillary muscle was excised and examined by electron microscope. In clinical experience, propranolol (20 microng/kg) was given intravenously to 6 patients who underwent open heart surgery. Transmural left ventricular myocardial biopsy was performed after the anoxic cardic arrest and the material, particularly the subendocardium, was examined by electron microscope. It was shown that propranolol was effective, both in the experiment and in the clinical experience, in preserving ischemic myocardium. The possible mechanisms through which propranolol might act were considered to be (1) indirect effect of altered oxygen supply vs. demand, effect by reducing heart rate and reducing cardiac output due to the drug's function as a beta blocker, (2) direct cellular effect, i.e., reducing myocardial substrate metabolism along with stabilization of cellular structure, and (3) increase collateral circulation to the subendocardium.

Cytological changes in chloride cells following altered ionic media

The rock-eel, Pholis, and guppy, Lebistes, adapted to fresh or saltwater were exposed to low concentrations of unnatural ions or transport inhibitors including thiocyanate, potassium and ouabain, which caused cytological alterations in the chloride cells of the gills. Some of the other substances used caused generalized damage to intracellular membranes. Highly ordered geometric arrays of the tubular reticulum were produced under certain conditions. The conditions of the experiments suggest that the tubular reticulum plays a role in ionic segragation and that the normal configuration of the reticulum is dependent on the ionic composition of the intracellular milieu.

Correlation of structure and active transport in the teleost nephron

In the present study we have extended our investigations concerning the correlation between ultrastructure and active transport in the isolated flounder nephron. The composition of the fish nephron is defined in ultrastructural terms and its behavior when incubated in vitro under short term and long term culture conditions is described. Using the in vitro system originally described by Forster, a variety of inhibitors and conditions which modify cell structure and function were tested. Ultrastructure was correlated with chlorphenol red dye transport. In general, conditions altering active transport also markedly altered cellular ultrastructure. The principal alterations consisted of membrane changes involving various organelles--most importantly the plasma membrane and the mitochondria. Conditions associated with irreversible cell injury could be rapidly produced by interference either with mitochondrial ATP synthesis or with the integrity of the plasma membrane. Both of these rapidly lead to irreversible events which are preceded by reversible structural changes. Organelle changes progress in a rather well-defined sequence of reversible and irreversible stages which are defined. One difference between the two types of interactions is the presence of intramitochondrial calcification which does not occur with direct modification of the mitochondrial electron transport system. The concept of utilizing long term explant organ cultures of fish nephrons for environmental studies is introduced.