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Y Kress

Publications and source records attributed to Y Kress.

At least 37 records · Page 2Linked to original sources
PubMed1997

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.

Animals↗
PubMed1996

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.

Animals↗
PubMed1995

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.

Adolescent↗
PubMed1995

Human microglia mediate anti-Cryptococcus neoformans activity in the presence of specific antibody.

The interaction of the opportunistic fungus Cryptococcus neoformans with human microglia was studied in vitro in the presence and absence of capsule binding antibody. In the absence of capsule binding antibody there was little or no phagocytosis. Addition of the murine monoclonal antibody (mAb) 2H1 (IgG1, kappa) to the capsular glucuronoxylomannan (GXM) produced a dose-dependent enhancement of C. neoformans phagocytosis by microglia. Phagocytosis resulted in marked inhibition of fungal proliferation. Microglial antifungal activity was studied by colony forming unit assay, L-[3H]leucine incorporation assay, and phase contrast microscopy. At microglia: C. neoformans ratios of 10:1 to 80:1 fungal growth was reduced by 61-95%. Inhibitors of nitric oxide synthase and reactive oxygen intermediates did not prevent antifungal activity mediated by human microglia. Transmission electron microscopic studies revealed that although some internalized yeast cells were killed, the majority were intact consistent with fungistasis. Human microglia cells are potent effector cells against C. neoformans in vitro in the presence of specific antibody. Enhancement of microglial activity in vivo by opsonins may be a useful therapeutic strategy.

Antibodies, Fungal↗
PubMed1995

Human microtubule-associated protein-2c localizes to dendrites and axons in fetal spinal motor neurons.

Microtubule-associated protein-2 (MAP-2) functions to maintain neuronal morphology by promoting the assembly of microtubules. MAP-2c is an alternately spliced form of MAP-2, containing the first 151 amino acids of high-molecular-weight (HMW) MAP-2 joined to the last 321 amino acids, eliminating 1,352 amino acids specific to HMW MAP-2. A polyclonal antibody generated to the splice site of human MAP-2c was used to determine its cellular localization. The MAP-2c antiserum was depleted of any HMW MAP-2 reactivity by absorption with HMW MAP-2 fusion protein. Western blot analysis of human fetal spinal cord homogenates demonstrated that the antibody is specific for human MAP-2c. MAP-2c immunoreactivity was found in the perinuclear cytoplasm and processes of anterior motor neurons and large processes of the posterior column in sections from 22-24-week human fetal spinal cord. Double-label confocal microscopy was performed using the MAP-2c polyclonal antibody and either a HMW MAP-2 or a neurofilament protein (highly phosphorylated 160- and 200-kDa protein) monoclonal antibody to identify these processes as dendrites or axons, respectively. HMW MAP-2 and MAP-2c colocalized in cell bodies and dendrites of anterior motor neurons, demonstrating for the first time the presence of native MAP-2c within dendrites. In addition, immunoelectron microscopy showed MAP-2c associated with microtubules in dendrites of motor neurons. MAP-2c and the neurofilament proteins were found in axons of the dorsal and ventral roots. The presence of MAP-2c within axons and dendrites suggests that MAP-2c contributes to neuronal plasticity during human fetal development.

Axons↗
PubMed1995

Cytotoxicity for lung epithelial cells is a virulence-associated phenotype of Mycobacterium tuberculosis.

Dissemination of viable tubercle bacilli from the lung is a critical event in the establishment of Mycobacterium tuberculosis infection. We examined the possibility that M. tuberculosis bacteria could infect and damage lung epithelial cells to determine whether direct penetration of the alveolar epithelium is a plausible route of M. tuberculosis infection. While both virulent H37Rv tubercle bacilli and the attenuated Mycobacterium bovis BCG vaccine strain were able to enter A549 human lung epithelial cells in culture, only the virulent tubercle bacilli were cytotoxic for both polarized and nonpolarized epithelial monolayers and macrophages. In addition, bacterial entry into epithelial cells, but not macrophages, was increased by intracellular passage through macrophages, suggesting enhancement of a bacterially mediated cell entry mechanism in bacteria grown within macrophages. These findings suggest that M. tuberculosis bacteria might have the ability to gain access to the host lymphatics and circulatory system by directly penetrating the alveolar epithelial lining of an infected lung.

Cell Line↗
PubMed1995

Cryptococcus neoformans survive and replicate in human microglia.

BACKGROUND: Cryptococcus neoformans (CN) is an opportunistic pathogen that can cause fatal meningoencephalitis in patients with immune deficiency. Among the central nervous system (CNS) cells that are infected by CN are perivascular microglia and macrophages. Little is known about the interaction of CN and CNS phagocytes at the cellular level. EXPERIMENTAL DESIGN: To better understand the fate of CN in microglia, we followed Ab-opsonized CN in human fetal microglial culture by phase-contrast microscopy, combined lighted microscopy and transmission electron microscopy of plastic-embedded monolayers, and immunocytochemistry for localization of capsular Ag. RESULTS: Phase-contrast microscopy revealed that microglia initially internalized and contained Ab-opsonized yeast cells within phagolysosomes. However, CN escaped from microglia and resumed extracellular growth 16 to 24 hours after being phagocytosed. Transmission electron microscopy/1-mu epoxy sections revealed that intracellular CN were localized in two types of phagosomes in microglia: spacious phagosomes (SP) and close-fitting phagosomes (CP). Three lines of evidence indicate that SP are the primary sites for intracellular CN survival and replication: (a) SP contained multiple, budding yeast cells, whereas CP contained only single yeast cells within a tightly bound phagosomal membrane; (b) the number of SP and the number of CN within SP increased considerably at 24 hours compared with at 2 hours; and (c) microglial cultures challenged with heat- or amphotericin B-treated CN had significantly fewer SP than those challenged with live CN. Both SP and CP phagosomes fused with lysosomes, suggesting that CN survival in SP was not due to failure of phagolysosomal fusion. In SP, there was attenuation and diffusion of capsular polysaccharide within the phagosome, whereas in CP the fungal capsules remained compact and homogeneous. Immunocytochemistry with an mAb directed to capsular glucoronoxylomannan supported continued synthesis of polysaccharide within SP. CONCLUSION: The results suggest that, in human microglia, CN survive and replicate within SP. Modification of CN capsular polysaccharide within SP may be a contributing factor to this aberrant microglial-CN interaction.

Animals↗
PubMed1994

Antisense MAP-2 oligonucleotides induce changes in microtubule assembly and neuritic elongation in pre-existing neurites of rat cortical neurons.

Microtubule-associated protein 2 (MAP-2) is an abundant component of the cytoskeleton present in dendrites and cell bodies of neurons of the CNS. To examine the biological function of MAP-2, two MAP-2 antisense (AS) oligonucleotides complementary to the 5' region of the rat MAP-2 cDNA were added to rat primary embryonic day 17-18 (E17-18) cultured cortical neurons 24 h after plating and neurite outgrowth and morphology studied. The treatment of primary cortical cultures with either of the two MAP-2 AS oligonucleotides resulted in decreased MAP-2 and reduction in the number of neuritic processes relative to the control or MAP-2 sense-treated cultures. By immunostaining and light microscopy the AS-treated neurons appeared smaller, more rounded, and less intensely stained for MAP-2 than the untreated or the MAP-2 sense-treated cultures. By electron microscopy disorganized microtubules and a reduction in the number of microtubules within neurites of the AS-treated cultures were observed. We conclude that MAP-2 continues to be required for microtubule spacing and stability within neurites once they have formed.

Animals↗
PubMed1994

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.

Animals↗
PubMed1993

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.

Aged↗
PubMed1993

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.

Animals↗
PubMed1993

Productive infection of human fetal microglia by HIV-1.

Central nervous system disease is a frequent finding in both pediatric and adult AIDS. Microglia have been shown to be the major target of HIV-1 infection in the central nervous system. However, studies in vitro concerning susceptibility of human microglia to HIV-1 infection reported conflicting results; microglia from adult brain showed productive infection by HIV-1, whereas microglia from fetal brain did not. To investigate this further and to define the possible mechanisms responsible for this difference, we prepared highly purified human microglial cell cultures from fetuses of 16 to 24 weeks' gestation and exposed them to monocytotropic (HIV-1 JR-FL and HIV-1 JR-CSF) isolates of HIV-1. Culture supernatants were examined for the presence of p24 antigen for a 4-week period after viral exposure. Concurrently, potential cytopathic effects and cellular viral antigen expression (gp41 and p24) were examined by light microscopy in combination with immunocytochemistry. The results showed that human fetal microglia can be productively infected by HIV-1 as judged by p24 antigen capture assay, syncytia formation, and gp41 and p24 immunoreactivity of infected microglia. In addition, by electron microscopy, numerous viral particles characteristic of HIV-1 were present both in the intracellular and extracellular compartments. Uninfected cultures or astrocytes overgrown in the microglial cultures did not show evidence of infection under identical experimental conditions. These data demonstrate that human fetal microglia, like their adult counterparts, are susceptible to HIV-1 infection in vitro and can support the production of virus.

Acquired Immunodeficiency Syndrome↗
PubMed1993

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.

Child↗
PubMed1992

Persistent productive HIV-1 infection of a CD4- human fetal thymocyte line.

Human fetal thymuses were obtained from abortuses of HIV-1 seronegative females. Thymocytes were isolated and cultured for 2 days with PHA. Thereafter, the culture was divided and half of the cells were exposed to the HIV-1 RF isolate for 4 h. After this incubation period, the HIV-1 exposed and nonexposed control cells were cultured in RPMI 1640 supplemented with IL-2 for 30 days and subsequently maintained in RPMI without the addition of growth factors. Long term culture of both HIV-1 exposed and control thymocytes has yielded two cell lines that have been maintained for more than 3 yr without the addition of growth factors. Flow cytometry using mAb that recognize T cell differentiation markers was used to analyze cell phenotypes. The HIV-1 exposed thymocyte cell line (E88/RF) was shown to be HIV-1 infected by p24 ELISA, reverse transcriptase activity, immunocytochemistry, in situ hybridization, polymerase chain reaction, electron microscopy, and to produce infectious particles by a syncytial forming assay. The non-HIV-1-exposed thymocyte cell line (T412) has remained negative by all criteria for HIV-1 infection. Flow cytometry showed the T412 cells to be positive for the T cell markers CD45, CD38, and CD4 but negative for all other markers tested. The E88/RF cells are positive for CD45 and CD38 but negative for CD4 and other markers. These data report the isolation of two human fetal thymocyte cell lines; one uninfected and susceptible to HIV-1 infection, and the other persistently and productively infected with HIV-1 with little cytopathology. These findings suggest that HIV-1 can persistently infect early T cells and may alter T cell differentiation.

CD4-Positive T-Lymphocytes↗
PubMed1992

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.

Choristoma↗
PubMed1992

Early myelination in the human fetal lumbosacral spinal cord: characterization by light and electron microscopy.

Myelination in the human central nervous system is well documented after 20 weeks of gestation (WOG). However, earlier stages of this process have not been described in detail, although it is assumed that human myelinogenesis is similar to that observed in other animals. We used light and electron microscopy to study myelination in the human lumbosacral spinal cord during the second trimester of gestation. The kinetics of myelin-associated gene expression were analyzed by immunocytochemistry using antibodies to the myelin markers myelin basic protein (MBP) and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase). These studies show that in 12-13 WOG specimens, occasional MBP-positive processes are found in developing white matter in areas distinct from the root entry zones. At this time, ultrastructural study revealed early investment of axons by glial processes and rare compacted myelin. CNPase staining was qualitatively and quantitatively less than that of MBP. The numbers of MBP- and CNPase-positive myelin sheaths increased with time, and by 24 WOG many were evident in all areas of the spinal cord except in the corticospinal tracts. Ultrastructural study of corresponding areas revealed many thin lamellae of compact myelin. This study provides initial normative data for early human myelination in the lumbosacral spinal cord and may serve as a baseline for future developmental and pathological studies.

Antibodies, Monoclonal↗
PubMed1992

HIV-1 infection of human fetal thymocytes.

Some neonates with congenital human immunodeficiency virus type 1 (HIV-1) infection exhibit immune dysregulation. This suggests that fetal CD4+ cells, possibly thymocytes, may be infected during gestation. If thymocytes are infected, this may result in a disruption of T-cell differentiation. To examine this hypothesis, normal human fetal thymocytes were established in tissue culture, characterized, and then exposed to HIV-1. On initial isolation, fetal thymocytes were analyzed for phenotypic markers by flow cytometry and assessed for T-cell function by mitogen-stimulated thymidine incorporation. The thymocytes comprised greater than 70% double positive (CD4+, CD8+) cells and responded to T- but not to B-cell mitogens. Thereafter, thymocytes were incubated in either tissue culture medium containing infectious HIV-1 or in control (HIV-free) medium. Infection of fetal thymocytes was determined by light and electron microscopy in combination with immunocytochemistry, molecular hybridization, and an infectious cell center (ICC) assay. After 1 week in culture, the thymocytes exposed to HIV-1 were positive by immunocytochemistry for the HIV-1-associated protein gp41. In addition, the presence of HIV-1 DNA was detected by molecular hybridization confirming infection of these cells. The ICC assay demonstrated the production of infectious HIV-1 particles and budding of mature virions was observed by electron microscopy. These studies demonstrate that human fetal thymocytes can be infected with HIV-1 in vitro and that this infection results in production of infectious virions. These results support the hypothesis that vertical transmission of HIV-1 in vivo may result in the infection of fetal thymocytes, which may contribute to postnatal HIV-1-associated pathologic conditions.

Cells, Cultured↗