Apoptotic-like changes in Lewy-body-associated disorders and normal aging in substantia nigral neurons.

In Parkinson's disease and other Lewy-body-associated disorders, the substantia nigra pars compacta undergoes degeneration, but the mechanism of cell death has not been previously described. The substantia nigra of normal and Alzheimer's disease cases were compared with substantia nigra from patients with Lewy-body-associated disorders (Parkinson's disease, concomitant Alzheimer's/Parkinson's disease, and diffuse Lewy body disease) using in situ end labeling to detect fragmented DNA. In situ end-labeled neurons demonstrated changes resembling apoptosis: nuclear condensation, chromatin fragmentation, and formation of apoptotic-like bodies. Ultrastructural analysis confirmed nuclear condensation and formation of apoptotic-like bodies. Apoptotic-like changes were seen in the substantia nigra of both normal and diseased cases; concomitant Alzheimer's/Parkinson's disease and diffuse Lewy body disease cases had significantly higher amounts of apoptotic-like changes than normal controls or Alzheimer patients. The finding of neuronal death by apoptosis may have relevance for the development of new treatment strategies for Parkinson's disease and related disorders.

Microcystin-LR-induced ultrastructural changes in rats.

The ultrastructure of hepatic, pulmonary, and renal lesions was evaluated in rats injected intraperitoneally with a lethal dose of microcystin-LR (MCLR, 160 micrograms/kg), a cyclic heptapeptide hepatotoxin produced by the blue-green algae, Microcystis aeruginosa. Hepatic lesions were first seen at 10 minutes post-dosing and consisted of mild widening of hepatocyte intercellular spaces centrilobularly. At 20 minutes post-dosing, hepatocyte plasma membrane alterations were more pronounced, consisting of plasma membrane invagination with formation of variably sized and shaped intracytoplasmic vacuoles, loss of microvilli along the sinusoidal face, and widespread, pronounced hepatocyte separation. By 30 minutes, the space of Disse was markedly widened. At 60 minutes post-dosing, centrilobular areas contained necrotic cells and apparently intact, isolated, organelles intermingled with erythrocytes and platelets. In less severely affected regions there was prominent hepatocyte rounding, and erythrocytes and platelets were present in the widened space of Disse. Large amounts of hepatocellular debris and intact hepatocytes were present in the pulmonary vasculature, while smaller amounts of debris were also seen in the glomerular and peritubular capillaries of the renal cortex. This study shows that initial lesions are confined to shape changes in the plasma membrane of hepatocytes. These changes are consistent with the hypothesis that microcystin-LR induces alterations in the hepatocyte cytoskeleton. Later changes consist of hepatocyte disassociation and necrosis, as well as endothelial damage, which allow release of hepatocytes and debris into the circulation with microembolism in lungs and kidneys.

Feline cytotoxic large granular lymphocytes induced by recombinant human IL-2.

Large granular lymphocytes (LGL) have been characterized phenotypically and functionally as cytotoxic T lymphocytes, NK cells or lymphokine-activated killer cells. The most prominent morphologic feature of LGL is large cytoplasmic granules that are thought to contain the molecules responsible for cell lysis. In this study, we describe the morphologic and functional characteristics of IL-2-dependent cytotoxic lymphocytes derived from feline PBL. Stimulation of feline PBL with Con A followed by culturing in 50 U of gibbon monkey IL-2 human rIL-2 induced long term lymphocyte cultures. These lymphocytes are cytotoxic for the feline leukemia virus-induced T cell lymphoma (FL74), in a 4-h 51Cr release assay. All cell lines are either constitutively cytotoxic for FL74 cells, or cytotoxic in a lectin-dependent cell cytotoxic assay, the latter being a characteristic of low passage cultures. In contrast, no cell lines express self lysis or lysis for other lines. [3H]TdR uptake showed that 1 U of human rIL-2 produces a 50% maximal proliferative response by feline lymphocytes suggesting a high degree of homology between the ligand binding sites of feline and human IL-2R. Feline cytotoxic lymphocytes possess abundant cytoplasm containing large azurophilic granules characteristic of LGL. These granules are bound by a bilipid membrane and contain numerous smaller membrane-bound vesicles 50 to 60 nm in diameter. A model is proposed, whereby subsequent to binding of LGL to target cell the large granules fuse to the LGL plasma membrane and release the small vesicles into the binding pocket. The vesicles then transport the lytic molecules directly and selectively to the target cell membrane.

Comparison of a cheetah herpesvirus isolate to feline herpesvirus type 1.

A cytopathogenic virus with size and structural characteristics of a Herpesviridae was isolated from a cheetah with severe ulcerative dermatitis. Restriction endonuclease analysis and cross-hybridization studies revealed that the isolate was related to feline herpesvirus type 1 (FHV-1). Antigenic comparison studies using anti-FHV-1 serum demonstrated the presence of common antigens in the FHV-1 and the isolate from the cheetah.

Cloacal papillomas in psittacines.

Papilloma-like masses affecting the cloaca of 19 Amazons, 16 macaws, 3 parrots, 1 conure, and 1 parakeet were examined. Papillomatous lesions were characterized by proliferation of the lining epithelium on thin fibrovascular stalks. Carcinoma in situ was diagnosed in the cloaca of a macaw in addition to the other 16 macaws with papillomas. Papillomavirus group-specific antigens were not detected in any of the 41 lesions, using the peroxidase-antiperoxidase technique. The DNA extracts from 6 different frozen papillomas did not contain papillomavirus genomes detectable by Southern blot hybridization, using an African gray parrot cutaneous papillomavirus as a probe. Evidence of an infective agent was not found by electron microscopic examination of 8 of the papillomas. Inoculations of partially purified homogenates of a cloacal papilloma from a yellow-crowned Amazon did not induce lesion formation on cloacal mucosa of an adult yellow-crowned Amazon, green and yellow macaw, sulphur-crested cockatoo, or mollucan cockatoo.

Visualization of cytoskeletal elements and associated retroviral antigens by immunogold transmission electron microscopy of detergent extracted cells.

Several investigators have reported an association between the cytoskeleton and viral antigens. In our laboratory, biochemical immunofluorescence and immuno-gold electron microscopy studies were conducted on TX-100 extracted NIH/3T3 cells infected with Moloney-murine leukemia virus. Cytochalasin B treatment causes reversible microfilament disruption and a concomitant decrease in virus production. No effect on microtubules was seen. Immunogold electron microscopy reveals an association between cytoskeletal actin and the viral antigens gp70 and p15E. The results of these immunocytological and biochemical studies indicate that the cytoskeleton may play an integral role in transport and processing of viral gene-envelope products.

Erythrocyte membrane alterations associated with the attachment and replication of Eperythrozoon suis: a light and electron microscopic study.

Erythrocytes from pigs with experimental porcine eperythrozoonosis were examined using light microscopy and scanning and transmission electron microscopy. Three distinct forms of Eperythrozoon suis were attached to the plasma surface of erythrocyte membrane. Erythrocytes were initially parasitized by one or several immature forms. Immature forms enlarged and developed into juvenile and mature forms. The parasite replicated by budding of small immature forms from larger immature forms, juvenile forms, and mature forms. Small immature forms attached to adjacent membrane of the same erythrocyte or a nonparasitized erythrocyte. E. suis organisms were intimately associated with, but distinctly separated from erythrocyte membrane by a 30-nm electron lucent zone. Cell membrane in this area was denser than adjacent nonparasitized membrane. Early interaction between erythrocyte membrane and small immature forms resulted in no membrane deformation, but as this form enlarged, it later became embedded in a deep cup-like membrane invagination. As the immature form developed into the juvenile form a shallow, broad-based depression was observed in the membrane. A similar depression that covered a greater surface area was observed in the membrane parasitized by the mature form. The interaction between the parasitic forms and erythrocyte membrane resulted ultimately in severe membrane deformation. Parasite-membrane interactions may play an important role in the development of misdirected immune responses in experimental porcine eperythrozoonosis.