Necrotizing cerebritis in an allogeneic bone marrow transplant recipient due to Cladophialophora bantiana.

We describe a necrotizing cerebritis in an allogeneic bone marrow transplant recipient caused by the neurotropic, dematiaceous fungus Cladophialophora bantiana. The patient presented 7 months after bone marrow transplantation with fever and sudden onset of left-sided weakness, followed shortly by cranial nerve III and VI palsies. The patient had a lesion (3.0 by 2.0 by 2.0 cm) of the right midbrain with extension to the pons, the left brain stem, and the right superior and the middle cerebellar peduncles. The diagnosis was made by microscopic examination and culture of a brain biopsy.     

Geminin regulates neuronal differentiation by antagonizing Brg1 activity

Precise control of cell proliferation and differentiation is critical for organogenesis. Geminin (Gem) has been proposed to link cell cycle exit and differentiation as a prodifferentiation factor and plays a role in neural cell fate acquisition. Here, we identified the SWI/SNF chromatin-remodeling protein Brg1 as an interacting partner of Gem. Brg1 has been implicated in cell cycle withdrawal and cellular differentiation. Surprisingly, we discovered that Gem antagonizes Brg1 activity during neurogenesis to maintain the undifferentiated cell state. Down-regulation of Gem expression normally precedes neuronal differentiation, and gain- and loss-of-function experiments in Xenopus embryos and mouse P19 cells demonstrated that Gem was essential to prevent premature neurogenesis. Misexpression of Gem also suppressed ectopic neurogenesis driven by Ngn and NeuroD. Gem's activity to block differentiation depended upon its ability to bind Brg1 and could be mediated by Gem's inhibition of proneural basic helix-loop-helix (bHLH)-Brg1 interactions required for bHLH target gene activation. Our data demonstrate a novel mechanism of Gem activity, through regulation of SWI/SNF chromatin-remodeling proteins, and indicate that Gem is an essential regulator of neurogenesis that can control the timing of neural progenitor differentiation and maintain the undifferentiated cell state.     

Characterization of psoriasiform and alopecic skin lesions in HLA-B27 transgenic rats.

We have previously reported a multisystem inflammatory disease in transgenic rat lines with high expression of HLA-B*2705 and human beta 2 microglobulin. Skin disease in these rats includes two predominant lesions: 1) marked psoriasiform dermatitis of the tail and digits; and 2) progressive alopecia of face, neck, trunk, and extremities. Here we present the results of a systematic survey of these lesions. Tail and digit skin showed psoriasiform hyperplasia of the epidermis associated with parakeratosis, with marked dermal and epidermal inflammation. The alopecic skin showed perifollicular and follicular mononuclear infiltration and increased numbers of atrophic follicles. Immunohistochemical analysis revealed that B27 expression was prominent on keratinocytes in hyperplastic epidermis where lymphocytic infiltrates were prominent, but was absent in the absence of inflammation. In alopecic lesions, B27 was strongly expressed on follicular epithelium and dermal hair papillae associated with mononuclear infiltrates. T cells, both CD8 and CD4, were most prominent in inflammatory lesions and rat MHC-II expression on keratinocytes, and follicular epithelium was dramatically increased. This study suggests that T cell-mediated immune mechanisms participate in development of cutaneous lesions in HLA-B27 transgenic rats.     

Broiler chickens as potential source of Campylobacter infections in humans.

Of 46 broiler chickens from a live poultry market in New York City, 38 (83%) harbored Campylobacter fetus subsp. jejuni in their rectal flora. The observed mean number of C. fetus per g of feces was 4.4 x 10(6). The organisms survived in the feces for at least 96 h at 4 degrees C whether stored in the gut or transferred to a vial. The best survival medium for pure cultures of C. fetus subsp.jejuni was heart infusion broth supplemented with sterile blood and kept in a microaerophilic atmosphere.     

The reflex effects of intralaryngeal carbon dioxide on the pattern of breathing

1. The reflex effects on the pattern of breathing and total lung resistance of introducing 30, 10 and 5% CO(2) in air into the larynx have been studied in anaesthetized and decerebrate cats breathing through a tracheostomy tube.2. Flowing 30% CO(2) into the larynx caused a two-phased response. First, respiratory frequency and tidal volume decreased, with a consequent fall in minute ventilation. After two to ten breaths, frequency remained slow, but tidal volume increased beyond the control level, so that minute ventilation was restored to control levels.3. Flowing 5 or 10% CO(2) into the larynx caused slowing of breathing with small and inconsistent changes in tidal volume. Minute ventilation was significantly diminished.4. Off effects, on re-introducing air into the larynx, after 2 and 10 min of CO(2) exposure, suggested that the reflex response diminishes with increased duration of exposure to CO(2).5. None of the concentrations of intralaryngeal CO(2) changed total lung resistance or compliance.6. CO(2) mixtures in the larynx generally caused no change in blood pressure or pulse rate of the cats.7. The reflex effects of intralaryngeal CO(2) were abolished by denervating the larynx.8. Hypoxic mixtures introduced into the larynx did not change breathing.     

Evaluation of a rapid enzyme-linked immunosorbent assay for IgG antibodies to Aspergillus fumigatus in the serological diagnosis of allergic aspergillosis

A range of 6 somatic and culture filtrate antigens of Aspergillus fumigatus were evaluated in a rapid ELISA procedure for anti-A. fumigatus IgG where the component incubation times had been reduced to 10 min. Sera from patients with allergic aspergillosis, patients with suspected allergic aspergillosis, and asthmatic patients with or without A. fumigatus precipitins were tested. For all antigens, levels of anti-A. fumigatus IgG were higher in patients with allergic aspergillosis than in the other 3 groups. Low levels of specific IgG were, however, detected in asthmatic patients who had no precipitins against A. fumigatus. None of the antigen preparations enabled all patients with proven or suspected allergic aspergillosis to be separated from the other 2 groups of asthmatic patients. Positive-negative discrimination in ELISA was achieved by the inclusion of 10 pools of precipitin test-negative sera from the 50 asthmatics without A. fumigatus precipitins. The number of sera that were classed as positive in ELISA ranged from 9 to 15 in the allergic aspergillosis group, depending on the antigen used; in the suspected aspergillosis group, the number of positive reactions ranged from 1 to 8, while in the asthmatics with precipitins, the number ranged from 0 to 2.     

Inhibition of HIV-1 expression by HIV-2

HIV-1 and HIV-2 are co-endemic in certain geographic areas. HIV-2 is more weakly pathogenic than HIV-1, and progression to AIDS occurs less frequently and over a longer period of time. Recent epidemiologic studies suggest that individuals infected with HIV-2 have a lower risk of HIV-1 infection. Both immune mechanisms and various modes of viral interference have been proposed to account for these results. Our findings, described in this paper, suggest that HIV-2 inhibits HIV-1 replication. To study the molecular interactions between HIV-1 and HIV-2, proviral clones were transfected alone or in combination into the human T cell line CEM. LTR-CAT indicator constructs were included for the purpose of monitoring viral promoter activity. Viral replication in transfected cells was monitored by p24 antigen capture assay of cell culture supernatants and Western blot analysis of cell extracts. HIV-2 inhibited HIV-1 replication as determined by intracellular and extracellular p24 antigen levels. Similar results were obtained with simultaneous virus infection using HIV-1 and HIV-2, rather than transfections of proviral DNA. Using cotransfection of HIV-1 and HIV-2 LTR indicator gene constructs, the mechanism of inhibition was found to be suppression of the HIV-1 LTR by HIV-2. The inhibitory effect of HIV-2 is not due to Tat-2, but appears to discriminate between the HIV-1 and HIV-2 LTRs based on differences in the Tat activation response element, TAR. These results suggest both a molecular mechanism for HIV-2 interference with HIV-1 replication and a potential molecular approach to therapy.     

Toxicity and immunogenicity of a verotoxin 1 mutant with reduced globotriaosylceramide receptor binding in rabbits.

The verotoxins (VT1 and VT2), produced by strains of enterohemorrhagic Escherichia coli, have been implicated in the pathogenesis of hemorrhagic colitis and the hemolytic uremic syndrome. To better understand the role of globotriaosylceramide (Gb3) receptor binding by the verotoxins in disease production, we examined the clinicopathologic effects of an intravenously (i.v.) administered verotoxin 1 mutant holotoxin (Phe30Ala) in rabbits. The substitution of alanine for phenylalanine 30 in the VT1 B subunit has been shown previously to reduce both Gb3 binding affinity and capacity in vitro. This reduction in receptor binding corresponded to a 10(5)-fold reduction in the toxic activity of VT1 on a Vero cell monolayer. In this study, purified 125I-labeled Phe30Ala was administered i.v. to rabbits to determine its specific distribution in rabbit tissues. In contrast to the rapid elimination of i.v. administered 125I-VT1 from the bloodstream, 125I-Phe30Ala had a 52-fold-longer half-life in serum and failed to localize preferentially in the gastrointestinal tract and central nervous system (CNS). Rabbits challenged with Phe30Ala at a dose equivalent to 10 times the 50% lethal dose (LD50) of VT1 showed no visible clinical symptoms typical of VT effect after 7 days. Administration of Phe30Ala at a dose equivalent to 100 times the LD50 of VT1, however, caused both clinical and histopathologic features indistinguishable from VT1 toxemia in rabbits, although the onset of symptoms was delayed. Rabbits were immunized with Phe30Ala and challenged i.v. with either 125I-VT1 or 125I-VT2. The specific uptake of 125I-VT1 in the gastrointestinal tract and CNS was totally inhibited in Phe30Ala immune rabbits. Only a partial decrease in target organ uptake was observed in Phe30Ala immune rabbits challenged with 125I-VT2. From this study, we conclude that Gb3 binding is responsible for target organ localization of VT1 and disease production in the rabbit. The ability of Phe30Ala to induce both strong antibody and protective responses against VT1 suggests that VT mutants with reduced receptor binding properties may be useful in vaccine strategies. A further reduction in the toxicity of Phe30Ala would be required for its use as a natural toxoid to protect against human verotoxigenic E. coli infections.     

Induction of heat shock proteins in lymphocytes increases with mitogen stimulation

The effect of the growth state of a cell on the ability of hyperthermia to induce the synthesis of heat shock proteins (HSPs) was studied in resting and concanavalin A (ConA)-stimulated lymphocytes. Hyperthermia induced the synthesis of hsp 110, hsp 90, hsc 70, and hsp 70 in both resting and ConA-stimulated lymhocytes, and ConA-treatment induced the synthesis of the hsp 90 and hsc 70 at normal temperature. The induction of the synthesis of hsp 110 and hsp 70 by hyperthermia was 3- to 6-fold higher for lymphocytes cultured with ConA for 12 and 24 h than in non-stimulated lymphocytes. Thus, lymphocytes induced to undergo proliferation showed a greater response to hyperthermia than resting lymphocytes.     

Expression of superoxide dismutase and catalase in rat brain as a function of age

Active oxygen species have been proposed to be involved in the aging process of the brain, therefore alterations of the levels of enzymes involved in the defence system against free radicals and other active species could substantially influence the aging process. In this study the enzyme activities of superoxide dismutase (Cu/Zn) and catalase as well as the relative levels of their mRNA were measured in the brain of Fischer F344 rats of various ages (5-37 months old). A gradual decrease in the activity of these enzymes (21-27%) was observed with increasing age. The alterations were paralleled by a decrease (39-40%) in the relative levels of these mRNA species. Thus the decrease in the activity of superoxide dismutase and catalase appears to be due to an age-dependent change in the expression of these genes.