Salmonella spp. in nestling common barn-owls (Tyto alba) from southwestern New Jersey

The prevalence of Salmonella spp. in nestling common barn-owls was investigated in southwestern New Jersey during the summer of 1985. Of 94 owls sampled by swabbing the cloaca, eight (8.5%) were found to harbor Salmonella spp. Three serotypes--S. thompson, S. tuindorp, and S. typhimurium--were identified. Five (20%) of the 25 nest sites examined (all of them in or near farm buildings or dwellings) contained Salmonella-positive owls.     

Metabolism of high density lipoprotein subfractions.

Over the past few years, new experimental approaches have reinforced the awareness among investigators that the heterogeneity of HDL particles indicates significant differences in production and catabolism of HDL particles. Recent kinetic studies have suggested that small HDL, containing two apolipoprotein A-I molecules per particle, are converted in a unidirectional manner to medium HDL or large HDL, containing three or four apolipoprotein A-I molecules per particle, respectively. Conversion appears to occur in close physical proximity with cells and not while HDL particles circulate in plasma. The medium and large HDL are terminal particles in HDL metabolism with large HDL, and perhaps medium HDL, being catabolized primarily by the liver. These novel kinetic studies of HDL subfraction metabolism are compelling in-vivo data that are consistent with the proposed role of HDL in reverse cholesterol transport.     

The immunopathology of experimental allergic encephalomyelitis (EAE). III. Differential in situ expression of strain 13 Ia on endothelial and inflammatory cells of (strain 2 x strain 13)F1 guinea pigs with EAE

This study was undertaken to determine if there is differential expression of the relevant strain-specific Ia antigen on endothelial and parenchymal inflammatory cells in the central nervous systems (CNS) of guinea pigs (GP) with acute experimental allergic encephalomyelitis (EAE). Adult inbred GP were sensitized with GP spinal cord homogenate and complete Freund's adjuvant. Strain 13 GP and (2 x 13)F1 hybrids developed clinical disease within 2 to 3 wk after sensitization, whereas strain 2 GP did not, although all sensitized GP had CNS mononuclear inflammatory infiltrates. By using monoclonal antibodies to strain-specific and framework Ia epitopes with an immunoperoxidase technique, the distribution and amount of the strain 2 and strain 13 Ia were analyzed. Equivalent strain 2 and strain 13 Ia expression was found in normal tissues from F1 animals. Strain 2 and strain 13 GP sensitized for EAE had increased strain-specific Ia staining of CNS vessels and inflammatory cells over controls. However, F1 GP with EAE had markedly increased strain 13, but not strain 2, Ia on CNS parenchymal vessels and mononuclear inflammatory cells (p less than 0.001, for both). These results suggest for the first time that specific major histocompatibility complex gene products are selectively expressed on endothelial and inflammatory cells in situ in immune reactions in the target organ of individuals of heterogeneous immunogenetic composition.     

Basement membrane components in healing rabbit corneal epithelial wounds: immunofluorescence and ultrastructural studies

The nature of the substrate that supports epithelial migration in vivo is of interest, particularly with respect to mechanisms of wound healing. Immunofluorescence and electron microscopy were used to search for common substrate components in prototype rabbit corneal wounds: epithelial scrape wounds, in which the corneal or conjunctival epithelium migrated over the denuded lamina densa of the corneal basement membrane (CBM), and superficial keratectomy, in which the corneal epithelium migrated over a bare stroma without CBM. The corneal epithelium moved rapidly over the CBM or stroma to cover the defect within 2-3 d, whereas the conjunctival epithelium required 1-2 wk. In all wounds, fibronectin and fibrin/fibrinogen were deposited onto the bare surface within 8 h after wounding and persisted under the migrating epithelium until migration was complete. Bullous pemphigoid antigen (BPA), a normal component of the CBM, was removed with the epithelium upon scrape wounding and reappeared in the CBM after migration was completed. In contrast, the conjunctival epithelium had a continuous subepithelial band of BPA out to the migrating tip. Laminin, also a normal component of the CBM, was not removed in the scrape wounds, indicating that the region of least resistance to shear stress was between the BPA and laminin layers. Laminin was removed by superficial keratectomy and was not detectable under the leading edge of the migrating cells. Laminin and BPA were restored in the CBM by 2-4 wk. Type IV collagen could not be detected in normal CBM, but was conspicuously present in conjunctival basement membrane and in blood vessels. Focal bands of type IV collagen did appear in the newly synthesized CBM 2-4 wk after keratectomy. These results argue that BPA, laminin, and type IV collagen are not essential for the migration of corneal epithelium during wound healing and support the hypothesis that fibronectin and fibrin/fibrinogen are the common, perhaps the essential, components of the provisional matrix that serves as a substrate until the permanent attachment components are regenerated.     

The immunopathology of experimental allergic encephalomyelitis. I. Quantitative analysis of inflammatory cells in situ

Acute experimental allergic encephalomyelitis (EAE) is a T cell-mediated, neurologic disease that is under immunogenetic control. We systematically analyzed the quantity and distribution of T cells, B cells, and macrophages in the central nervous system (CNS) of susceptible and resistant guinea (GP) with a panel of seven monoclonal antibodies by using the avidin-biotin complex (ABC) immunoperoxidase technique and alpha-naphthyl-butyrate esterase (ANBE) staining. Adult EAE-susceptible strain 13 GP immunized with isogeneic spinal cord homogenate (SC) or with myelin basic protein (MBP) developed clinical signs (paralysis, weight loss, etc.) in 2 to 3 wk. T cells were present in all CNS inflammatory foci and comprised 44% of the perivascular mononuclear cells. T cells diffusely infiltrated the neuropil away from inflammatory cell aggregates. These T cells were judged to be extravascular by the lack of an associated identifiable vessel in counter-stained sections, and by their persistence following exhaustive perfusion of the brains. In routine sections, mononuclear cells could be detected only in perivascular aggregates. IgM+ B cells comprised 9% of the perivascular infiltrates and did not diffusely infiltrate the parenchyma. ANBE+ macrophages comprised the remaining 47% of the identified perivascular cells. SC- and MBP-immunized GP showed equivalent numbers of inflammatory foci, T cells, and macrophages, but SC-immunized GP had more IgM+ cells in the meninges and choroid plexus (p less than 0.001, p less than 0.02, respectively). Virtually all cells in perivascular locations were Ia+. Ia+ mononuclear cells were also present in the neuropil. EAE-resistant strain 2 GP immunized with SC developed no clinical signs. These GP had fewer perivascular foci than strain 13 GP but, when present, the cellular composition, including the density of diffuse parenchymal T cell infiltrates, was indistinguishable. Significantly fewer parenchymal mononuclear cells in the strain 2 GP, however, displayed Ia, both in perivascular and diffuse infiltrates (p less than 0.001). We conclude that T cell migration into the CNS parenchyma is a characteristic feature of acute EAE in the GP, but that T cells can occur in this pattern without clinical signs of disease. The two features that distinguish susceptible and resistant strains were the frequency of perivascular infiltrates and the expression of Ia on parenchymal mononuclear cells, which probably reflects their enhanced immunologic activation in situ.     

Differential recovery of circulating T cell subsets after nodal irradiation for Hodgkin's disease

To better understand the immunologic effects of lymphoid irradiation (LI), blood levels of T cell subsets were sequentially monitored in 15 patients before, during, and after irradiation treatment for Hodgkin's disease. Blood levels of all lymphocytes, T cells, and T cell subsets (defined by OKT4 and OKT8) fell dramatically and in similar proportions during early therapy, reaching levels less than 20 to 25% of control by the completion of mantle irradiation, and continuing at very depressed levels through the completion of therapy. Blood levels of OKT8-reactive (OKT8+) cells returned to pretreatment levels (402 +/- 38/mm3 vs 360 +/- 32/mm3 pretreatment) between 6 to 8 mo after LI, whereas blood levels of OKT4-reactive (OKT4+) cells returned to only 42% of previous values (242 +/- 22/mm3 vs 584 +/- 34/mm3 pretreatment) over the same period. The pre-LI ratio of OKT4+ to OKT8+ cells was 1.85 +/- 0.24 and fell to 0.65 +/- 0.05 between 6 to 8 mo after LI. During the recovery period, discrepancies of 208 +/- 32 cells/mm3 (3 to 5 months post LI) and 198 +/- 32 cells/mm3 (6 to 8 mo post LI) developed between the blood levels of OKT3+ cells and the sum of OKT4+ and OKT8+ cells. This suggests the emergence of OKT4+/OKT3-, OKT8+/OKT3-, and/or OKT4+/OKT8+ cells. In five patients, the sum of OKT4+ and OKT8+ cells was compared with the number of cells simultaneously co-stained by OKT4 and OKT8. It appeared that a significant proportion of the cells were OKT4+/OKT3- and OKT8+/OKT3- lymphocytes. We concluded that LI is similarly cytotoxic to peripheral blood T cell subpopulations. The reversed ratio after LI is a result of a slower repopulation of the peripheral blood by OKT4+ cells relative to OKT8+ cells. T cells after LI show a high degree of antigenic immaturity. It is postulated that the bone marrow that lies outside the fields of treatment and contains predominantly immature OKT8+/OKT3- cells is a major source of T cells repopulating the peripheral blood after LI.     

In vivo effects of monoclonal antibody to ICAM-1 (CD54) in nonhuman primates with renal allografts

These studies test whether allograft rejection can be blocked by interference with leukocyte adhesion, using a murine IgG2a mAb (R6.5) reactive with monkey ICAM-1 (CD54). In 16 Cynomolgus renal allograft recipients, R6.5 was administered prophylactically as the sole immunosuppressive agent for 12 days (0.01 to 2 mg/kg/day). Survival in 14 recipients with technically successful grafts was significantly prolonged (24.2 +/- 2.4 vs 9.2 +/- 0.6 days for controls; p less than 0.001). Intercellular adhesion molecule-1 (CD54) (ICAM-1) was expressed on vascular endothelium in the kidney and other organs in the monkey in a pattern similar to that in humans. During cellular rejection in controls, ICAM-1 expression increased on endothelial cells, infiltrating mononuclear leukocytes and tubular cells. Biopsies during R6.5 administration showed decreased T cell infiltration (CD2, CD8, CD4) compared with controls and decreased arterial endothelial inflammation. No changes occurred in circulating T cells, aside from variable coating with mIgG. In six of eight other recipients R6.5 administration (0.5 to 2 mg/kg/day for 10 days) reversed preexisting rejection that resulted from taper of Cyclosporine to subtherapeutic levels. Responding grafts showed decreased edema and hemorrhage but no consistent change in the infiltrate. At 1 h after the first dose, mouse IgG deposited primarily on the graft vascular endothelium without any change in the inflammatory infiltrate. Mouse IgG also deposited on the endothelium of normal organs without eliciting an inflammatory response and was cleared from the endothelium within 4 days. Inasmuch as the principal site of binding was the vascular endothelium, we hypothesize that the antibody blocks adhesion to graft ICAM-1 molecules on the vessels. Anti-ICAM-1 also binds to recipient cells and may interfere with Ag presentation and/or T cell interactions. Whatever the mechanism(s), these studies indicate that an anti-ICAM-1 antibody inhibits T cell mediated injury in vivo, and that ICAM-1 is a critical molecule in the pathogenesis of allograft rejection.     

Non-covalent DNA groove-binding by 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine.

The cooked meat mutagen 2-amino-1-methyl-6-phenyl-imidazo[4,5-b]pyridine (PhIP) is metabolized in vivo to electrophilic intermediates that covalently bind to DNA guanines. Here we address the mechanism of PhIP's non-covalent interaction with DNA by using spectroscopic and computational methodologies. NMR methodologies indicated that upon addition of DNA, PhIP aromatic protons underwent a small, 0.11-0.12 p.p.m. upfield shift. DNA phosphorus resonances of non-covalent PhIP-DNA complexes broadened and slightly shifted upfield, while DNA base imino proton resonances shifted slightly downfield relative to DNA alone. UV and fluorescence spectra of PhIP titrated with DNA showed no detectable shifting and hypochromism of absorbance or fluorescence bands. In the presence of DNA, PhIP fluorescence was efficiently quenched by acrylamide, but not by silver ion. Further, the NMR spectra suggest that PhIP is in fast exchange with the DNA, and is slightly specific for adenine-thymine (A-T) sequences. Finally, structural arguments based on quantum chemistry calculations suggested that PhIP and its metabolites are unlikely to intercalate into DNA. These data collectively indicate that PhIP non-covalently binds in a groove of DNA.