Madeleine Bastide

Prevention of Clostridium difficile-induced experimental pseudomembranous colitis by Saccharomyces boulardii: a scanning electron microscopic and microbiological study

The ability of Saccharomyces boulardii to protect mice against intestinal pathology caused by toxinogenic Clostridium difficile was studied. Different regions of the intestine of experimental mice were prepared for observation by scanning electron microscopy or homogenized for C. difficile enumeration and quantification of toxin A by enzyme immunoassay and toxin B by cytotoxicity. The test group was treated for 6 d with an S. boulardii suspension in drinking water and challenged with C. difficule on day 4. The three control groups were: axenic mice, mice treated with only S. boulardii and mice only challenged with C. difficile. The results showed that: (i) 70% of the mice infected by C. difficile survived when treated with S. boulardii; (ii) the C. difficile-induced lesions on the small and large intestinal mucosa were absent or markedly less severe in S. boulardii-treated mice; and (iii) there was no decrease in the number of C. difficile but rather a reduction in the amount of toxins A and B in S. boulardii-treated mice.

Biological effects of continuous exposure of embryos and young chickens to electromagnetic fields emitted by video display units

The effects of continuous exposure of embryos and young chickens to electromagnetic fields (EMFs) emitted by video display units (VDUs) were investigated. Embryos and brood were continuously exposed during embryonic and postembryonic phases to EMFs emitted by two types of VDU (TV or computer). Embryonic mortality was evaluated in three independent experiments. Young chickens were immunized three times by porcine thyroglobulin (Tg). Blood samples were assayed after each immunization for specific anti-Tg antibodies (IgG), plasma corticosterone (CORT), and plasma melatonin (MLT). In the sham-exposed samples, embryonic death (10-33%) was restricted to the perinatal period and the IgG, CORT, and MLT responses of young chickens crested after the second immunization. Constant EMF exposure was accompanied by significantly increased fetal loss (47-68%) and markedly depressed levels of circulating anti-Tg IgG, CORT, and MLT. Collectively, these findings indicate that continuous exposure to EMFs, issuing from VDUs, adversely affects embryos and young chickens.

Effect of calcitonin gene-related peptide and vasoactive intestinal peptide on murine CD4 and CD8 T cell proliferation.

The effects of alpha calcitonin gene-related peptide (alpha CGRP) and vasoactive intestinal peptide (VIP) on the proliferation of CD4 and CD8 T-murine lymphocytes were investigated. When stimulated by a combination of phorbol 12-myristate-13-acetate (PMA) and calcium ionophore (A23187), both neuropeptides in a range of 10(-7)-10(-10) M had an inhibitory effect on the proliferative response of unfractionated splenocytes as well as of purified CD4 and CD8 T lymphocytes. The inhibitory effect of these two neuropeptides was completely or partially blocked by the antagonists of CGRP and VIP receptors. CGRP8-37 and (p-Cl-D-Phe6, Leu17VIP, respectively. The inhibitory effects of each neuropeptide on purified T cells were observed within 4 h after PMA/A23187 activation and their inhibitory actions were correlated with a decrease of IL-2 production. In addition, the two neuropeptides in a range of 10(-7)-10(-10) M induced a rapid and dose-dependent increase in intracellular cAMP in CD4 and CD8 T cells. This suggests the involvement of this second messenger in the inhibitory effects of these two neuropeptides. Taken together these results show that CD4 and CD8 spleen cells represent at least two of the cellular targets for CGRP and VIP inhibition of proliferation mediated by the same type of mechanism.

A role for bursa fabricii and bursin in the ontogeny of the pineal biosynthetic activity in the chicken

Abstract: The tripeptide bursin (Lys‐His‐Gly‐NH2) is a B cell differentiation hormone derived from the bursa fabricii. The latter is a cloacal diverticulum and the site of B lymphocyte differentiation and selection in aves; also the bursa fabricii is involved in endocrine functions. Herein we demonstrate that in the chicken, the bursa fabricii and bursin are crucial to the ontogeny of both the pineal response to antigenic challenge and pineal circadian synthetic activity. In early embryonically bursectomized chickens, the plasma melatonin response to immunization by porcine thyroglobulin (Tg) was abolished. Also, the amplitudes of both plasma melatonin and pineal N‐acetyltransferase (NAT) circadian rhythms were reduced by 50%, whereas the activity of hydroxyindole‐O‐methyltransferase (HIOMT) remained unchanged. Conversely, administration of either minute amounts (100 pg, 100 fg) or highly dilute (5 × 10−27 g) bursin, with the exception of a highest dose (100 μg), to bursaless embryos induced recovery of normal antigen‐induced melatonin response and normal amplitudes of melatonin and NAT rhythms. These findings establish that early in embryonic life, the bursa fabricii and its derived signal (bursin) are essential for normal development of pineal synthetic activity and underline the efficacy of very dilute bursin as an informative signal.

Taxonomic Significance of Yeast Sphaeroplast Release after Enzymic Treatment of Intact Cells

Treatment of whole yeast cells with a mixture of a reducing agent and 1,3-beta-glucanase isolated from Basidiomycete QM806 led to the production of sphaeroplasts from ascomycetes, from some fungi imperfecti, but not from basidiomycetes. Association of 1,3-beta-glucanase with a second enzyme, 1,4-alpha-glucanase, from Trichoderma viride, was required for sphaeroplast release from some, but not all, basidiomycetes and fungi imperfecti. The ability of yeast cells to liberate sphaeroplasts following appropriate enzymic treatment is proposed as a taxonomic criterion for differentiating basidiomycetous from ascomycetous yeasts and for classifying fungi imperfecti yeasts.

Kinetics of appearance of intestinal lesions in mice mono-associated with a lethal or non-lethal strain of Clostridium difficile

The kinetics of the appearance of intestinal lesions induced by orogastric inoculation of gnotobiotic mice with a lethal strain of Clostridium difficile (VPI) that produced toxins A and B in vivo and in vitro was studied and compared with the lesions induced by non-lethal C. difficile strain 786 that produced toxins A and B in vitro but only toxin B in measurable amounts in vivo. Different portions of the intestine were removed 12, 20, 26 and 30 h after inoculation and studied by scanning electronmicroscopy. The remaining portions were homogenised for enumeration of C. difficile and quantification of toxin A by enzyme immunoassay and toxin B by cytotoxicity. The results showed that, following inoculation: (i) measurable amounts of both toxins were necessary to produce lesions; (ii) with strain VPI, the caecum and the colon were rapidly impaired and completely destroyed after 1 day, whereas the small intestine was damaged to a lesser extent; (iii) C. difficile strain 786 did not cause mucosal damage but induced mucus-like or serum-like secretion and morphological changes in the caecal enterocytes only.

Factors Involved in Catheter Obstruction During Long-Term Peritoneal Insulin Infusion

OBJECTIVE To analyze the efficacy of ECPII and the factors responsible for technical problems often encountered. This treatment has been in use with IDDM patients since 1980. RESEARCH DESIGN AND METHODS Forty-four IDDM treated by ECPII for 42–78 mo (mean, 53 mo). patients were RESULTS Glycemic equilibrium was improved during treatment (mean plasma glucose level, 7.6 mM; mean GHb level, 8%). Catheter blockage was the main reason for ECPII failure (74%). Mean catheter survival of each catheter, determined by actuarial analysis, was 11.7 mo and significantly decreased with subsequent implantation. SEM of the catheter tips showed deposits composed of fibrin and cells occluding the inner lumen. Factors such as age, sex, local infection, and low insulin basal rate were not found to have any incidence on the catheter survival. Placement of the catheter in the upper part of the peritoneum, however, increased catheter survival. Anti-insulin antibodies did not seem to be directly involved in blockage. CONCLUSIONS We conclude from this long-term experience that during ECPII, catheter blockage remains the major recurring complication, probably involving a local immune-inflammatory response in the peritoneum.

An efficient immunization protocol for production of monoclonal antibodies against soluble human insulin

A new immunization protocol has been developed to obtain specific monoclonal antibodies (mAb) directed against the soluble form of human insulin. Various protocols differing on the basis of the nature of immunogen, the number of injections and the route of administration of the antigen were compared. Mice with the highest anti-insulin titers were selected for cell fusion. The results showed that the immunization protocol involving 2 injections of insulin followed by a boost 2 months later mainly stimulated B lymphocytes secreting IgM mAb directed against immobilized insulin. Immunization with 2 injections of human proinsulin followed by 2 injections of a human insulin-bovine serum albumin conjugate and finally with a booster injection of this conjugate on each of the last 4 days preceding fusion was necessary to obtain a high percentage of hybridomas secreting specific IgG mAb able to recognize immobilized insulin (indirect ELISA) as well as iodinated insulin (liquid-phase radioimmunoassay).

The Role of the Bursa of Fabricius and Highly Dilute Bursin in Immunoneuroendocrine Interactions in the Chicken

A huge set of data, pertaining to Mammals namely, supports the existence of two-way communication between the immune and neuroendocrine systems. For example, glucocorticoids released by the adrenals are immunodepressive; in turn, immune products act at different levels of the hypothalamo-pituitary-adrenal axis (HPA) (for review see Lilly and Gann, 1992). Also, the chief pineal hormone melatonin (MLT) is immunostimulatory (Maestroni et al., 1989) whereas interferon-γ stimulates the release of MLT by cultured pineal glands (Withyachumnarkul et al., 1990). The concept that products of the immune system act on the neuroendocrine system was suggested by (1977), based on their observation that in rats, serum corticosterone (CORT) increases during the course of immune response. However, in Mammals, most studies working out immunoneuroendocrine interferences deal with the T immune component mainly, therefore neglecting the involvement of the B lymphoid compartment, because the latter is rather anatomically diffuse. Therefore, it appears experimentally difficult to identify specific B immune signal (s) endowed with neuroendocrine competence.