Mitochondrial abnormalities in Alzheimer's disease.

The finding that oxidative damage, including that to nucleic acids, in Alzheimer's disease is primarily limited to the cytoplasm of susceptible neuronal populations suggests that mitochondrial abnormalities might be part of the spectrum of chronic oxidative stress of Alzheimer's disease. In this study, we used in situ hybridization to mitochondrial DNA (mtDNA), immunocytochemistry of cytochrome oxidase, and morphometry of electron micrographs of biopsy specimens to determine whether there are mitochondrial abnormalities in Alzheimer's disease and their relationship to oxidative damage marked by 8-hydroxyguanosine and nitrotyrosine. We found that the same neurons showing increased oxidative damage in Alzheimer's disease have a striking and significant increase in mtDNA and cytochrome oxidase. Surprisingly, much of the mtDNA and cytochrome oxidase is found in the neuronal cytoplasm and in the case of mtDNA, the vacuoles associated with lipofuscin. Morphometric analysis showed that mitochondria are significantly reduced in Alzheimer's disease. The relationship shown here between the site and extent of mitochondrial abnormalities and oxidative damage suggests an intimate and early association between these features in Alzheimer's disease.

The effect of the echinocandin analogue caspofungin on cell wall glucan synthesis by Cryptococcus neoformans.

The echinocandin derivative caspofungin (MK-0991, L-743,872) inhibits 1,3-beta-d-glucan synthesis and is active against several medically important fungi but is relatively ineffective against Cryptococcus neoformans. To investigate the mechanism of C. neoformans resistance, the prevalence of 1,3- and 1,6-beta-d-glucan linkages was determined in cells grown with and without caspofungin, using affinity-purified antisera and gold particle immunoelectron microscopy. Cryptococcal strains ATCC 24067 (serotype D) and MY2061 (serotype A) were studied. Growth at 4 microg/mL of caspofungin reduced both glucan linkages in both strains. However, growth at 2 microg/mL resulted in reduced 1,6-beta-d-glucan linkage only for MY2061. Inhibition of 1,6-beta-d-glucan synthesis may be an additional mechanism of action for pneumocandins. The relatively low efficacy of caspofungin against C. neoformans may result from reduced activity against C. neoformans glucan synthase or from yet undiscovered mechanisms of action operative in other fungal pathogens but not in C. neoformans.

Induction of Alzheimer-specific Tau epitope AT100 in apoptotic human fetal astrocytes.

In Alzheimer's and other neurodegenerative diseases, hyperphosphorylated tau accumulates in affected neuronal and glial cells in the form of paired helical filaments (PHFs). This tau binds antibody AT100, which recognizes the double phosphorylation site (Thr212/Ser214) that is not present in normal biopsy tau. In primary cultures, highly enriched (>98%) in astrocytes of human fetal brain, three polypeptides of 52, 64, and 70 kD showed immunoreactivity with tau antibodies against non-phosphorylated epitopes, accounting for 88, 12, and <1%, respectively, of the total reactivity. All three polypeptides were phosphorylated at the PHF-1 epitope but not at the epitopes Tau-1, 12E8, AT8, and AT100. Treatment of cultures with okadaic acid resulted in apoptosis characterized by the blebbing of the plasma membrane, condensation of nuclear chromatin, and fragmentation of the nucleus. This treatment also resulted in a 3- to 5-fold increase in the content of both tau protein and phosphorylation. The increases were observed in all phosphorylation sites examined, and included the AT100 site. The AT100 site has been proposed to be generated by protein kinase B/Akt and Cdc2. Since okadaic acid can induce an AD-like hyperphosphorylated state of normal tau in primary cultures of human brain cells, a simple cellular model is available permitting study of self-aggregation of tau and phosphorylation events characteristic of neurodegeneration.

Intracellular passage within macrophages affects the trafficking of virulent tubercle bacilli upon reinfection of other macrophages in a serum-dependent manner.

SETTING: The interaction of tubercle bacilli with macrophages is central to understanding of tuberculosis disease. OBJECTIVE: The objective was to determine whether prior passage within macrophages affects the behavior of Mycobacterium tuberculosis (Mtb) upon re-entry into other macrophages. DESIGN: Transmission electron microscopy was used to monitor fusion of bacterial phagosomes with late endosomal/lysosomal compartments using thoria as a fluid phase marker. Two-dimensional polyacrylamide gel electrophoresis was used to study bacterial protein expression within macrophages. RESULTS: H37Rv and BCG expressed novel proteins within macrophages. H37Rv also underwent less fusion after intracellular (IC) (24.2+/-7.7%) than extracellular (XC) (67.4+/-5.5%) passage when the bacteria entered new macrophages in small clusters. These effects were inhibited by serum, and were not observed with H37Ra or BCG bacteria (78.9+/-1.6% fused for all conditions). In addition, vacuoles which contained single bacilli were less likely to acquire markers (26.9+/-2.6%) than those that contained multiple bacilli (77.3+/-2.8%). CONCLUSION: These results indicate that phagolysosomal fusion patterns can be modulated by a variety of factors and that virulent Mtb bacteria may express proteins within macrophages that alter their interaction with these host cells.

cAMP-dependent protein kinase phosphorylations on tau in Alzheimer's disease.

To elucidate the role cAMP-dependent protein kinase (PKA) phosphorylations on tau play in Alzheimer's disease, we have generated highly specific monoclonal antibodies, CP-3 and PG-5, which recognize the PKA-dependent phosphorylations of ser214 and ser409 in tau respectively. The present study demonstrates by immunohistochemical analysis, CP-3 and PG-5 immunoreactivity with neurofibrillary pathology in both early and advanced Alzheimer's disease, but not in normal brain tissue and demonstrates that cAMP-dependent protein kinase phosphorylations on tau precede or are coincident with the initial appearance of filamentous aggregates of tau. Studies using heat-stable preparations demonstrate that neither site appears to be phosphorylated to any appreciable extent in normal rodent or human brain. Further analysis demonstrates that the beta catalytic subunit of PKA (Cbeta), the beta II regulatory subunit of PKA (RIIbeta), and the 79 kDa A-kinase-anchoring-protein (AKAP79), are tightly associated with the neurofibrillary pathology, positioning cAMP-dependent protein kinase to participate directly in the pathological hyperphosphorylation of tau seen in Alzheimer's disease.

The M cell as a portal of entry to the lung for the bacterial pathogen Mycobacterium tuberculosis.

M. tuberculosis accesses the terminal lung and is phagocytosed by alveolar macrophages. Utilizing a mouse intratracheal challenge model, we demonstrate that M. tuberculosis rapidly enters through M cells as well. From there, bacilli are deposited within associated intraepithelial leukocytes and subsequently conveyed to the draining lymph nodes early after infection. Osteopetrotic (Csfm(op)/Csfm(op)) mice, null mutants for macrophage colony-stimulating factor, possess diminished numbers of circulating monocytes and tissue macrophages. Csfm(op)/Csfm(op) mice were highly susceptible to challenge with M. tuberculosis. In contrast to controls, tubercle bacilli were not conveyed to draining lymph nodes early after infection but were instead retained within the mucosa. These results indicate that M cells represent an alternate portal of entry for M. tuberculosis, which may contribute to the rapid development of protective lung immune responses.

Herpesvirus-associated papillomas in koi carp (Cyprinus carpio).

From January through November 1994, 32% (7/22) of koi carp (Cyprinus carpio) maintained in indoor aquariums developed proliferative cutaneous lesions that consisted of single to multiple 2-10-mm whitish to pink fleshy masses usually associated with fin rays. Although scaleless koi were more commonly affected (3/6) than were normally scaled koi (4/16), the difference in incidence rates was not significant (chi2 text, P > 0.05). Lesions typically resolved spontaneously in 1-3 wk, occasionally persisted for >3 mo, and recurred in several fish after 2-5 mo. Fish were otherwise asymptomatic. Wet mount preparations from lesions were densely cellular and consisted of hyperplastic epidermal cells of normal morphology without parasites or inflammatory cells. Histologically, biopsies were consistent with papillomas and were characterized by a marked benign epidermal hyperplasia without inclusion bodies or inflammatory infiltrate. Transmission electron microscopic examination revealed intranuclear and intracytoplasmic herpesvirus virions. Virus isolation attempts were unsuccessful.

Mitotic phosphoepitopes precede paired helical filaments in Alzheimer's disease.

We have shown previously that the TG-3 and MPM-2 antibodies recognize phosphoepitopes common to mitosis and degenerating neurons of Alzheimer's disease(AD) brain. Here, we have evaluated their occurrence in human brain biopsy tissue, and confirm that they are absent in mature neurons of adult brain, but reappear during neurodegeneration in AD. The TG-3 epitope appears ahead of the MPM-2 epitope and is distributed throughout the neuronal soma. Tau is the major TG-3 antigen in AD brain. The initial localization of MPM-2 immunoreactivity in primary dendrites, it's robust occurrence in granulovacuolar bodies, and the increased immunoreactivity with 300-350-kDa proteins, suggest MAPI B as a candidate MPM-2 antigen in AD. Production of mitotic phosphepitopes in more than one type of human neurodegenerative lesion implicates mitotic kinases as common mediators of neuronal death. Because mitotic phosphoepitopes appear before paired helical filaments, it is suggested that mitotic kinase activation triggers neurofibrillary tangle formation. Future studies will need to focus on factors influencing mitotic kinase activity, a point with potential for early diagnosis and disease abrogation.

Fibrous long-spacing collagen in bacillary angiomatosis.

Fibrous long-spacing (FLS) collagen is a distinct ultrastructural form of collagen present in normal tissue, various tumors, and tissues degraded by bacterial collagenases in vivo and in vitro. An association between FLS collagen and bacillary angiomatosis has not been previously described. Six cases of bacillary angiomatosis, including one autopsy case with disseminated disease, were examined ultrastructurally. In addition, Kaposi sarcoma (3), pyogenic granuloma (3), capillary hemangioma (3), and cavernous hemangioma (2) were examined for comparison. A vascular proliferation in a lymph node from a patient with AIDS (1) and a case of pulmonary capillary hemangiomatosis (1), also in an AIDS patient, were studied. Abundant FLS collagen was identified in 4 of 6 cases of bacillary angiomatosis, in close association with the organisms. FLS collagen was not seen beyond the immediate vicinity of the organisms. The FLS collagen in bacillary angiomatosis was seen in skin biopsies and in lung and skeletal muscle in the autopsy case; in the latter case, as well as in the two AIDS-associated, nonbacillary angiomatosis, non-Kaposi sarcoma vascular proliferations, there was a striking distribution of FLS collagen around small blood vessels. Occasional FLS collagen was observed in all three pyogenic granuloma. When present in pyogenic granuloma, FLS collagen was intermixed with subendothelial collagen. Abundant FLS collagen was identified in close association with the organisms of bacillary angiomatosis in four cases; this morphologic alteration was seen in skin as well as lung and skeletal muscle. An association between FLS collagen and endothelial cells in normal tissue (Descemet's membrane) and in certain vascular proliferations appears to exist.

Eosinophil-Cryptococcus neoformans interactions in vivo and in vitro.

Eosinophils are components of inflammatory responses to a variety of pathogens. Although a variety of beneficial and harmful functions have been ascribed to these cells, their role in protection against infectious agents remains uncertain. Previous studies have reported eosinophilic pneumonia in mice infected intratracheally with Cryptococcus neoformans. We confirmed this observation and studied the inflammatory response in the lung at day 14 by light and electron microscopy. Immunostaining for glucuronoxylomannan showed isolated cryptococci inside the eosinophilic cuffs. Eosinophils were found to be in close association with C. neoformans in vivo. Cryptococci were associated with eosinophils within eosinophilic perivascular cuffs, within granulomas, and lining the alveolar space. To further investigate this phenomenon in vitro, we isolated rat peritoneal eosinophils and studied cryptococcus-eosinophil interactions in the presence and absence of anti-capsular immunoglobulin G1 (IgG1) and IgE monoclonal antibody (MAb). Eosinophils phagocytosed C. neoformans only in the presence of specific antibody. Phagocytosis was rapid, and dense rings that appeared to consist of granule contents were formed around the organisms. Mast cells were observed to occasionally phagocytose C. neoformans in vitro in the presence of IgE MAb. Our observations suggest that eosinophils may be effector cells against C. neoformans.

Adenosarcoma of the uterus with extensive smooth muscle differentiation: ultrastructural study and review of the literature.

Four cases of Mullerian adenosarcoma were studied by light and electron microscopy and immunohistochemistry. All 4 cases showed the histologic characteristics of adenosarcoma with benign endometrial glands and a malignant stroma. Ultrastructurally, the epithelial component in all cases had the appearance of proliferative endometrial glands, and the malignant mesenchymal cells showed features of endometrial stroma. A distinct basal lamina separating glands from stroma was present. In addition, 2 of the cases showed extensive smooth muscle differentiation which was associated with sarcomatous overgrowth. The smooth muscle features were confirmed by immunohistochemistry. Multiple theories of the histogenesis of this tumor are discussed.

Effects of protein calorie malnutrition on tuberculosis in mice.

Infectious diseases and malnutrition represent major burdens afflicting millions of people in developing countries. Both conditions affect individuals in industrialized nations, particularly the aged, the HIV-infected, and people with chronic diseases. While malnutrition is known to induce a state of immunodeficiency, the mechanisms responsible for compromised antimicrobial resistance in malnourished hosts remain obscure. In the present study, mice fed a 2% protein diet and developing protein calorie malnutrition, in contrast to well-nourished controls receiving a 20% protein diet, rapidly succumbed to infection with Mycobacterium tuberculosis. Malnourished mice exhibited a tissue-specific diminution in the expression of interferon gamma, tumor necrosis factor alpha, and the inducible form of nitric oxide synthase in the lungs, but not the liver. The expression of these molecules critical to the production of mycobactericidal nitrogen oxides was depressed in malnourished animals in the lungs specifically at early times (< 14 days) after infection. At later times, levels of expression became comparable to those in well-nourished controls, although the bacillary burden in the malnourished animals continued to rise. Nevertheless, urinary and serum nitrate contents, an index of total nitric oxide (NO) production in vivo, were not detectably diminished in malnourished, mycobacteria-infected mice. In contrast to the selective and early reduction of lymphokines and the inducible form of nitric oxide synthase in the lung, a marked diminution of the granulomatous reaction was observed in malnourished mice throughout the entire course of infection in all tissues examined (lungs, liver, and spleen). Remarkably, the progressively fatal course of tuberculosis observed in the malnourished mice could be reversed by restoring a full protein (20%) diet. The results indicate that protein calorie malnutrition selectively compromises several components of the cellular immune response that are important for containing and restricting tuberculous infection, and suggest that malnutrition-induced susceptibility to some infectious diseases can be reversed or ameliorated by nutritional intervention.

Acinic cell carcinoma of the lacrimal gland.

An 18-year-old woman underwent exenteration of the right orbit for tumor recurrence 3 years subsequent to external-beam irradiation for a lacrimal gland tumor diagnosed as an "adenocarcinoma." Light microscopy of the exenteration specimen revealed an acinic cell carcinoma of the lacrimal gland, with a predominant microcystic (latticelike) pattern of growth. Cytoplasmic vacuoles and the secretion within the microcysts stained positive with periodic acid-Schiff with and without alpha-amylase, alcian blue (at a pH of 2.5), mucicarmine, and colloidal iron with and without hyaluronidase. This histochemical staining for epithelial mucins supports the theory that the lacrimal gland, although serous in type, may also function as a modified mucus gland. There was cytoplasmic immunopositivity for keratin (CAM 5.2, KAE 1-3); immunostaining for vasoactive intestinal polypeptide was negative. Electron microscopy disclosed undifferentiated features of intercalated duct cells. We speculate that the lack of immunoreactivity for vasoactive intestinal polypeptide may be correlated with the predominantly undifferentiated intercalated duct cell features observed ultrastructurally.

Experimental approaches to mechanisms of protection and pathogenesis in M. tuberculosis infection.

It has, for many years, been widely assumed that the fundamental mechanism of protection in tuberculosis infection is a CD4 T cell response producing lymphokines that activate macrophages to kill or restrict the intracellular growth of M. tuberculosis. Just as certain cytokines, e.g. IFN-gamma, are currently perceived to be important for protection, others, particularly tumor necrosis factor (TNF), are thought to be responsible for much of the tissue destruction associated with the disease. Yet there are remarkably few critical experimental or clinical data that have defined the immunological requirements for protection and pathogenesis. One of the initial stimuli to the work we have undertaken has been careful reflection on the results of the many prospective trials of BCG against tuberculosis. Two aspects have impelled us to reconsider conventional wisdom. The first, of course, is the wide discrepancy in the degree of protection imparted, ranging from 0% in South India to 77% in the British MRC trial (1, 2). The second is that, in all trials that examined them, skin test conversions to tuberculin positivity were 85% or greater, indicating a disparity between the presence of delayed hypersensitivity to tuberculin and protection. We and others have argued (1, 2) that there are multiple possible explanations for this discrepancy, the principal one being protection caused by infection with environmental mycobacteria. But, the general point raised is whether cell mediated immunity as manifested by CD4+ cell production of lymphokines and macrophage activation is a sufficient mechanism for protection against M. tuberculosis infection.

Visceral myogenic tumors. A manifestation of HIV infection in children.

We report a primary smooth-muscle tumor of undetermined malignant potential of the liver in a child with acquired immune deficiency syndrome (AIDS). This patient represents the eighth child infected with the human immunodeficiency virus who developed a mesenchymal tumor other than Kaposi's sarcoma. All these children were younger than 10 years of age. These tumors often were histologically or clinically malignant and all but one were smooth-muscle tumors. These tumors arose exclusively in visceral organs, and the hepatobiliary, gastrointestinal, and tracheopulmonary systems were involved. Transmission of the virus occurred both vertically (in six children) and via blood transfusion (in two). Given the rarity of smooth-muscle tumors in uninfected children, the unusual frequency of these tumors suggests that immunosuppression induced by the virus permits the unregulated proliferation of a primitive mesenchymal cell disposed to myogenous differentiation, a situation not unlike that observed in the development of AIDS-related Kaposi's sarcoma in adults.

Pathogenesis of tuberculosis: interaction of Mycobacterium tuberculosis with macrophages.

Central to understanding the pathogenesis of tuberculosis is the interaction between the pathogen and mononuclear phagocytes. A key question about that interaction is whether Mycobacterium tuberculosis exerts an effect on phagolysosome fusion. We have reexamined the dynamics of phagolysosome fusion and its effect on intracellular bacterial replication in M. tuberculosis-infected macrophages by performing an extensive study at the electron microscopic level. Thoria-labelled murine and human macrophages were infected with a virulent (H37Rv) or avirulent (H37Ra) strain of M. tuberculosis or with Mycobacterium bovis BCG vaccine for times ranging from 2 h to 7 days. In all cases, by 2 h postinfection, approximately 85% of the bacteria clearly resided in fused vacuoles. However, at 4 days postinfection, fusion levels for viable H37Rv and H37Ra were reduced by half, whereas the fusion profiles of BCG and of heat-killed H37Rv and H37Ra were unchanged. A comparison of the numbers of bacteria per fused and nonfused vacuoles suggests both a net transfer of bacteria out of fused vacuoles and preferential bacterial multiplication in nonfused vacuoles. H37Rv and H37Ra appeared to bud from the phagolysosomes into tightly apposed membrane vesicles that did not fuse with secondary lysosomes. In some cases, no such membrane was seen and the bacteria appeared to be free in the cytoplasm. Only viable H37Rv showed a significant increase in bacterial counts during the course of infection. Thus, both of the attenuated strains we examined differed from the virulent strain H37Rv in their abilities to replicate successfully within macrophages, but each diverged from H37Rv at a different point in the process. Viable tubercle bacilli H37Rv and H37Ra had the capacity to escape from fused vesicles as the infection progressed; BCG did not. After extrusion from the phagolysosome, H37Rv, but not H37Ra, was able to multiply. These results suggest a novel mechanism by which virulent M. tuberculosis eludes the microbicidal mechanisms of macrophages by escaping from fused phagolysosomes into nonfused vesicles or the cytoplasm.

Phosphorylated tau immunoreactivity of granulovacuolar bodies (GVB) of Alzheimer's disease: localization of two amino terminal tau epitopes in GVB.

An immunocytochemical study of Alzheimer's disease hippocampus with a panel of anti-tau antibodies revealed two antibodies that stained granulovacuolar bodies (GVB) in pyramidal neurons of Ammon's horn. These two affinity-purified anti-tau antibodies were raised in rabbits against synthetic peptides homologous to sequences (amino acids 44-55 and 75-87) in the 58 amino acid insert in the amino terminus of the longest form of human tau. This region is homologous to exons 2 and exon 3 of bovine tau. The exon 2 peptide contains a serine (amino acid residue 46), which has been shown to be a phosphorylated site in paired helical filaments. Antibodies to a nonphosphorylated exon 2 peptide failed to immunostain GVB, but those to the phosphopeptide consistently stained GVB. Staining, however, was most consistent with the antibody to the exon 3 sequence. As in previous studies, GVB were also stained by RT97, a neurofilament antibody whose epitope in tau appears to be a phosphorylated site in or near exon 2, perhaps at serine residue 46 (Brion et al. 1992). Antibodies to epitopes in the amino terminus, mid-region and carboxy terminus of tau failed to consistently stain GVB. More often they produced staining around the periphery of the GVB, giving the appearance of an "empty vacuole." Most GVB were also immunoreactive with an antibody to ubiquitin. The results are consistent with the hypothesis that GVB are derived from sequestered altered tau possibly mediated by ubiquitin. The failure to detect most regions of tau in GVB is consistent with the idea that tau is partially degraded or highly modified in GVB.

Phakomatous choristoma of the eyelid. Immunohistochemical and electron microscopic observations.

BACKGROUND: A 13-month-old Hispanic boy underwent excision of a congenital inferonasal orbital mass arising from the right lower lid. Results of histopathologic examination of the tumor showed a phakomatous choristoma of the eyelid. An immunohistochemical and electron microscopic study of this rare, benign, congenital tumor of lenticular anlage was performed. METHODS: Immunohistochemistry was performed on 4-microns thick sections from paraffin-embedded tissue. Electron microscopy was performed on thin sections stained with uranyl acetate and lead citrate. FINDINGS: The cuboidal epithelial cells that comprise this choristoma showed strongly positive cytoplasmic staining with S-100 protein and vimentin and focally positive staining with a keratin cocktail (AE1/AE3). Electron microscopy showed the presence of numerous 10-nm whorled cytoplasmic microfilaments within degenerating epithelial cells. CONCLUSION: The immunoreactivity of this tumor to keratin and vimentin are newly described in this detailed clinicopathologic report and, together with its S-100 positivity, support the proposal that this tumor is of lenticular anlage. The authors hypothesize that the intracytoplasmic 10-nm intermediate filaments observed with electron microscopic examination within the epithelial cells that comprise this choristoma represent vimentin as detected by immunohistochemistry.