Identification of Rickettsia rickettsii in a guinea pig model by immunofluorescent and electron microscopic techniques

Moribund guinea pigs infected with Richettsia rickettsii were examined by necropsy, histology, immunofluorescence, electron microscopy, and serology. Untreated animals died at 9 and 10 days after inoculation. Animals given saline subcutaneously survived from 1 to 4 days longer. Prolonged survival was accompanied by more severe lesions: scrotal necrosis; infarction of ears; and swollen, hemorrhagic footpads, epididymis, and cremaster muscle. Histopathologic examination demonstrated that acute, necrotizing vasculitis, perivascular hemorrhage, and focal necrosis were more extensive. Direct immunofluorescence indicated many more rickettsiae in endothelium and vascular wall of saline recipients. Ultrastructurally, typical rickettsiae were present focally in the cytoplasm of endothelial and vascular smooth muscle cells. Cytopathology in infected and adjacent cells included swelling, mitochondrial enlargement with decrease in matrix density and loss of cristae, and increased pinocytosis. In addition, treated animals had more cytonecrosis, thrombosis, extravascular fibrin deposition, prominent inflammatory cells with polymorphonuclear phagocytosis of rickettsiae, and antibody production.

Ultrastructural renal lesions in goats given a lethal dose of imidocarb diproprionate

Ultrastructural renal lesions were studied in 20 goats given one intramuscular injection of a lethal dose of imidocarb diproprionate (6.75 mg/kg). The lesions were limited to proximal convoluted tubular epithelial cells and at postinjection (PI) hour 3 included: plasma membrane disruption, smooth endoplasmic reticulum proliferation and dilatation, swelling and increased electron density of mitochondria, and cytoplasmic ground substance rarefaction. At PI hour 12, disruption of plasma membranes, with fragmentation of the microvilli, loss of junctional complexes, and cellular detachments from in tact basement membranes were observed in many tubular epithelial cells. Mitochondrial configurational alterations became more prominent at 6 and 12 hours, with the formation of large membrane-bounded structures containing fragmented cristae, clear vacuoles, and amorphous matrical material. The intramitochondrial foci of electron-dense amorphous flocculent material, which was first observed at 6 hours and increased in electron density and in number by 12 and 24 hours, were probably comprised of denatured, clumped matrical protein. The 2nd type of intramitochondrial and cytoplasmic electron-dense deposit was observed PI hour 24. The basement membranes remained intact in most proximal tubules to support regenerating epithelial cells on PI day 4 and thereafter.

Tourniquet ischemia: ultrastructural and histochemical observations of ischemic human muscle and of monkey muscle and nerve

Biopsies of muscle from ten patients and of muscle and nerve from three monkeys were obtained during periods of continuous ischemia and studied by light and electron microscopy and by histochemical means. Between the third and fourth hours of ischemia, swelling of the mitochondria was noted in monkey muscle. One week later the appearance was normal. In the monkey nerves degenerated myelin was seen one week later but appeared to be normal at 2 weeks. If after 3 hours the tourniquet was deflated for 30 minutes and then reapplied for 2 additional hours, no changes were found. Succinic dehyrogenase analysis was used to identify swelling of the mitochondria. No mitochondrial changes were seen in human muscle made ischemic by a tourniquet for 2 hours.

Ultrastructural effects of Helminthosporium maydis race T toxin on mitochondria of corn roots and protoplasts

Zea mays inbred W64A in Texas (T, toxin sensitive) male sterile and non-male sterile (N, toxin resistant) cytoplasms were utilized. Roots of freshly germinated seeds were treated for 15 min of 2 hr with culture filtrate from liquid grown Helminthosporium maydis Race T, or with a chloroform extractable purified fraction from the culture filtrate. In the susceptible W64A T line, toxin treatment, both crude and purified, caused swelling and loss of matrix densiy in mitochondria of root cap and vacuolated cells in the region of elongation. One hour treatment with the chloroform extractable toxin fraction caused similar effects or mitochondria of isolated leaf protoplasts. This is the first report of such rapid in vivo effects of HmT toxin on mitochondria. Difficulty in obtaining consistent preservation of meristem mitochondria precluded drawing firm conclusions concerning that region of the root. In the resistant W64A N line, protoplast and root mitochondria were unaffected by the toxin.

[Mitochondrial morphology and metabolism in extrahepatic obstruction (author's transl)]

Corresponding to the increased activity of mitochondrial Glutamate-Dehydrogenase (GLDH) in serum in extrahepatic cholestasis a swelling of hepatic mitochondria could be shown on ultrastructural morphometric analysis. The morphometric alterations parallel the serochemical findings. A significant correlation could be calculated between the swelling of mitochondria and the activity of GLDH in serum.

Changes in the mitochondria in the initial part of the axon during regeneration

The initial part of the axon including the axon hellock, the initial unmyelimated segment and the beginning of myelinated axon was studied electron microscopically during regeneration, 1--30 days following a crush lesion of the rat hypoglossal nerve. Large mitochondria reaching 1.1 mum in diameter, with abundant cristae and dense granules in the matrix were observed between days 3--21. They formed clusters in the initial myelinated segment of the axon. End-to-end contacts and ribosomes around them were very often visible. The large mitochondria exhibited strong succinate dehydrogenase and NAD - H2 diaphorase activities. The relationship between the appearance of large and active mitochondria in the initial part of the axon and the elevated axonal transport during regeneration of the peripheral nerve is also discussed.

An electron microscopic study of pig liver viability after extracorporeal storage

The effects of hyperbaric oxygenation and ambient pressure oxygenation on the viability of pig liver stored in the Vickers' transportable organ storage unit were assessed by electron microscopy. It was found that hyperbaric oxygenation resulted in marked liver damage in contrast to ambient pressure storage. Although electron microscopy proved to be a sensitive method for detecting damage induced by unsuitable storage protocols consideration is given to the possibility that other changes, which may not be detectable by electron microscopy, limit the success of liver storage.

Studies on the pathogenesis of ischemic cell injury. V. Morphologic changes of the pars convoluta (P1 and P2) of the proximal tubule of rat kidney made ischemic in vitro

In summary, we have described the time course of changes of mitochondria following ischemia of the kidney proximal tubule. The sequence of morphological changes of matrix as well as inner membrane corresponds well with certain functional or physical parameters such as swelling, respiration, substrate metabolism, acceptor control and P/O ratio. This indicates that morphological parameters can be utilized to predict the functional alterations of mitochondria following ischemia in cells. The significant mitochondrial changes are early loss of granules (15-30 min) and condensation (15 min), swelling (30 min), appearance of fluffy densities (30 min) and flocculent densities (after 60 min), degeneration of cristal structure (240 min) and disintegration of mitochondria as structural units (24 h).

[Oxidative processes in tissues of the nematode Mecistocirrus digitatus]

The tissues of the nematode M. digitatus were used to obtain mitochondria which swell under the effect of several factors. Intensive oxidation of succinate, fumarate, malate, oxalacetate, alpha-ketoglutarate and less intensive one -- of citrate, isocitrate and pyruvate were observed in the mitochondria; cis-aconitate was not oxidized at all. NAD and NADP increased the intensity of substrate oxidation, whereas parachlormercuribenzoate, malonate and benzoate decreased the latter.

Permeability measurements on mitochondria from wild-type and poky strains of Neurospora crassa

The permeability properties of isolated Neurospora mitochondria were determined by measuring the rate at which the mitochondria swell in isotonic solutions of various organic and inorganic molecules. Like mammalian mitochondria, wild-type Neurospora mitochondria were impermeable to sucrose and only slightly more permeable to most inorganic ions (K, Na, Cl). Their permeability to K was greatly increased by valinomycin and by monensin. In addition, the mitochondria contain specific systems mediating PO4 uptake and PO4- malate, fumarate, and succinate exchange. Mitochondria from the maternally inherited poky strain of Neurospora, previously demonstrated to possess defective ribosomes and a grossly cytochrome chain, showed a slight but significant increase in permeability to inorganic ions. They contained, however, the specific uptake and exchange systems for phosphate and dicarboxylate anions, a result suggesting that these systems do not depend upon mitochondrially synthesized polypeptides.

Naturally-occurring degeneration in chick muscle development: ultrastructure of the M. complexus

Ultrastructural study of the M. complexus muscle of the chick embryo has demonstrated two populations of fibres: the more common is the normal myotube or muscle fibre, which was observed in various stages of development; the other shows myofibrillar contractions which, at their greatest degree, produce the appearance of an amorphous mass of myofilaments. The contracted fibre had rounded and swollen mitochondria, and vacuoles (autophagic) containing glycogen, and it exhibited a cleavage of the cell which isolated the nuclear region from the main body of the fibre. When the fibres were less contracted they resembled degenerative mammalian fast-twitch-oxidative-glycolytic fibres after immobilization. The more normal fibre population was identical with that of the pectoralis muscle, which was used as a control. These results suggest that the contracted fibres are degenerating, which agrees with conclusions by earlier investigators using light miscroscopy.

[Ultrastructural changes of the stria vaseularis and the spiral ligament in chronic uremic rats (author's transl)]

Looking for the morphological correlation of uremic inner ear damage a 5/6 resection of kidney parenchyma in rats was performed. A biochemically proven chronic uremia was so created. The ultrastructural examination of the stria vascularis showed a marked swelling of the intermediate cells, compressing occasionally stria vessels. The stria was enlarged and the mitochondria of the dark and light cells swollen. In the spiral ligament connective tissue cells were moderately swollen and blood vessels partially obstructed by swelling of the endothelium. These changes are proved not to be dependent on the urea. The pathophysiological significance for uremic inner ear damage can only be determined after further examination of cochlear tissue.

Identification of a membrane protein involved in mitochondrial phosphate transport

A specific labeling by radioactive N-ethylmaleimide of a protein involved in phosphate transport was obtained by protecting one of the two-SH-groups of the transport system with low concentrations of mersalyl. Subsequently, the other free-SH groups were blocked with excess N-ethylmaleimide. Removal of mersalyl by cysteine and subsequent inbucation with labeled N-ethylmaleimide results in a "specific" binding of N-ethylmaleimide to one-SH group functionally involved in phosphate transport. The isolated inner membrane fraction of the labeled mitochondria was subjected to dodecylsulfate gel electrophoresis. The followin results were obtained. 1. The difference of the radioactivity pattern on the dodecylsulfate-polyacrylamide gel of inner membrane proteins, labeled with N-[14C]ethylmaleimide in the absence and with N-[3H-A1-ethylmaleimide in the presence of mersalyl during preincubation of mitochondria, shows only one main labeled peak. The same labeled peak is obtained from the difference of labeling after preincubation with a constant low concentration of mersalyl at 32 degrees C and at 0 degrees C. 2. The position of the labeled peak on the dodecylsulfate-polyacrylamide gel corresponds to a protein of molecular weight of 26500 +/- 800. 3. The amount of one of the two-SH groups, involved in phosphate transport, was estimated to be 30 nmol per g of mitochondrial protein.

Linear densities in mitochondria of human myocardial cells

Ultrastructural study of myocardial biopsies from 5 patients who underwent myocardial revascularization procedures because of impending infarction showed mitochondria with linear densities. These densities, which occupied the intracristal space, appeared to have a high protein but low mineral content. It is suggested that linear densities may be an expression of severe, acute myocardial cell injury.

Osmotic behavior and permeability of osmotically lysed mitochondria

Experiments were carried out with water-treated isolated rat liver mitochondria (mitochondria ghosts) previously studied by Caplan and Greenawalt (Caplan, A.I., and J.W. Greenawalt. 1966. J. Cell Biol. 31:455-472) and Vasington and Greenawalt (Vasington, F., and J. Greenawalt. 1968. J. Cell Biol. 39:661-675). The ghosts have permeability properties and osmotic behavior comparable to those of isolated mitochondria. Although they have lost most of their internal contents, they must have resealed. Four properties were found which have not been previously described in systems derived from biological membranes: (a) an osmotic behavior in the virtual absence of internal components. (b) a self-arranging property in the formation of invaginations corresponding in morphology to the cristae. The results suggest that the assembly of the molecular components of the inner membrane is sufficient to specify the morphology. Hence the surface area to volume ratio of the vesicles may specify the presence or absence of cristae-like folds. (c) an increase in the permeability of the membranes to sucrose in the presence of iso-osmotic concentrations of sucrose. (d) an independence of the light transmitted by suspensions of the vesicles from the refractive index of the external medium. This observations run counter to the general previous experience with either mitochondria or liposomes.

The effect of endo-enteric development of Toxoplasma gondii on the ultrastructure of epithelial cells of the small intestine of infected cats

Toxoplasma gondii undergoing endo-enteric development in the small intestine of the cat affects the ultrastructure of the epithelial cells. The epithelial cells from infected cats have swollen rough endoplasmic reticulum and the mitochondria may be swollen with degenerate cristae. A statistically significant shortening of the microvilli of the epithelial cells was demonstrated. It appeared that the effect on the microvilli length was related to the parasite distribution within the small intestine. These changes occur in both cells with and without parasites present at the level of the sections studied. The abnormalities are quickly rectified after the disappearance of the endo-enteric forms of Toxoplasma.

Structure and function of cardiac mitochondria in exhausted guinea pigs

The ultrastructure and functional capacity of mitochondria from hearts of exhausted guinea pigs were compared to those from rested animals. Electron micrographs of heart ventricles were examined for ultrastructural alterations, and functional capacity was studied by oxygen polarography. General swelling of mitochondria from exhausted animals was indicated by a 41% reduction in mitochondrial surface/volume ratio and a 22% increase in volume density of mitochondria from exercised animals when compared to those from controls. The yield of isolated mitochondria from exhausted guinea pigs was similar to that for control animals. In the presence of all substrates tested the rate of oxygen consumption was lower in the exhausted animals than in the controls. The ADP/O ratios and respiratory control indices for pyruvate, succinate and ascorbate were not systematically affected by exercise. With glutamate as substrate respiratory control was reduced in exercised guinea pigs. These experiments suggest that the structure of myocardial mitochondria from exhausted animals is sufficient to maintain normal ADP/O ratios but is not adequate to maintain normal rates of respiration.

Ultrastructural studies on the endometrium of women wearing TCu-200 intrauterine devices by means of transmission and scanning electron microscopy and x-ray dispersive analysis

Endometrial biopsies obtained from 12 young women wearing TCu-200 intrauterine contraceptive devices from six to 12 months were studied by means of transmission and scanning electron microscopes as well as with the use of rubeanic acid stains and x-ray dispersive analysis. Six biopsies were taken at Day 10 and six were taken at Day 20 of the menstrual cycle. The aim was to investigate epithelial and stromal changes possibly related to copper deposition. The main changes were located in the cell organelles at Day 10 of the cycle. The mitochondria disclosed vacuolization of the matrix and myelin figure formation in 70 to 80% of the epithelial cells. There were also increased numbers of lysosomes. There were similar alterations of secretory endometrium in only a few cases. Instead, there was an increased number of mitochondria, and most of them were dividing. Rubeanic acid stains as well as energy-dispersive x-ray analysis failed to reveal significant amounts of copper in the various cell organelles studied. The above observations seem to indicate that there is a definite alteration of the mitochondria of epithelial cells which may result in impairment of respiratory mechanisms and energy production, rendering the endometrial environment inhospitable to the fertilized egg. These changes are thought to be reversible. The absence of copper is explained on the basis of a rapid turnover of the endometrium or to a problem in sampling common to this methodology.

Glutamate metabolism and transport in rat brain mitochondria

1. The metabolism and transport of glutamate and glutamine in rat brain mitochondria of non-synaptic origin has been studied in various states. 2. These mitochondria exhibited glutamate uptake and swelling in iso-osmotic ammonium glutamate, both of which were inhibited by N-ethylmaleimide. 3. The oxidation of glutamate was inhibited by 20% by avenaciolide, but glutamine oxidation was not affected. 4. These mitochondria, when metabolizing glutamine, allowed glutamate, but very little aspartate, to efflux at considerable rates. 5. These results suggests that brain mitochondria of non-synaptic origin possess in addition to a relatively rapid glutamate-aspartate translocase, a relatively slow aspartate-independent glutamate-OH-translocase (cf. liver mitochondria).