A simple and reliable method to screen isolates of Escherichia coli and Klebsiella pneumoniae for the production of TEM- and SHV-derived extended-spectrum β-lactamases

Objective: To evaluate which of 24 β-lactams used in susceptibility tests best discriminated between strains of Klebsiella pneumoniae and Escherichia coli that produce extended spectrum β-lactamases (ESBLs) from strains that produce older, more familiar, plasmid-mediated β-lactamases such as TEM-1 and SHV-1.
Methods: Susceptibility to the 24 β-lactam agents was determined by agar dilution and disk diffusion methodologies, using 27 strains of K. pneumoniae and E. coli that produced 22 different older plasmid-mediated β-lactamases and 28 strains that produced 17 different ESBLs.
Results: In general, strains that produced ESBLs were intermediate or resistant to cefpodoxime, whereas those that produced other β-lactamases were susceptible to this agent. The agar dilution test exhibited 96% sensitivity and 100% specificity in discriminating these two groups of organisms. The disk diffusion test exhibited 100% sensitivity and 96% specificity. All other β-lactam agents tested were inferior discriminators between the two groups of organisms.
Conclusions: Agar dilution and disk diffusion tests with cefpodoxime can be used to discriminate strains of K. pneumoniae and E. coli that produce ESBLs from those that produce older, plasmid-mediated β-lactamases.     

Direct detection of verotoxin genes in stool samples by polymerase chain reaction in hemolytic uremic syndrome patients in France

Objective: To reassess the occurrence of verocytotoxin-producing Escherichia coli (VTEC) in French hemolytic uremic syndrome (HUS) patients.
Method: From March 1991 to January 1995, direct detection of verotoxin genes (VT) by the polymerase chain reaction (PCR) was performed on stool samples from 169 patients suffering from HUS.
Results: Fifty-one were PCR positive (30.1%); one was positive for the VT1 gene and the others for the VT2 gene. VTEC was isolated from only 32 of the 51 PCR-positive samples. E. coli O157:H7 was isolated from five patients. E. coli O111 was isolated from seven patients during an outbreak of HUS. Among the other VT2 E. coli strains, only four were serotypable. Of the 51 PCR-positive stools, 19 were culture negative for VTEC.
Conclusions: This study provides evidence that in France E. coli O157 and other VTEC serotypes are involved in HUS.     

Effect of human serum on bioluminescence of natural and recombinant luminescent bacteria

Biphasic modification of bacterial bioluminescence by human serum was revealed: bioluminescence was inhibited at high concentrations of the serum and stimulated at low concentrations. Effects of temperature and duration of exposure on bioluminescence manifested in stimulation of the inhibitory effect at higher temperature and longer exposure. The degree of inhibition of bioluminescence under in the presence of serum depends on species characteristics of the microorganism and nature of the luminescent system. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 138, No. 9, pp. 311–315, September, 2004     

Use of λgt11 and monoclonal antibodies to map the gene for the 60,000 dalton glycoprotein of infectious laryngotracheitis virus

To localize the gene encoding the 60 kD glycoprotein (gp60) of infectious laryngotracheitis virus (ILTV), a library of the ILTV genome was constructed in the gt11 expression vector. Twelve recombinant bacteriophages expressing gp60 epitopes as fusion products with -galactosidase were detected by immunoscreening with monoclonal antibodies specific for gp60. The ILTV DNA sequence contained in one of these recombinants 24-4 was used as a hybridization probe for mapping the insert sequence on the viral genome. The gene for the gp60 was located at map unit 0.72–0.77 in the unique long region (U_L) of the ILTV genome. The DNA sequence of the 1.2 kb insert of 24-4 containing the gp60 epitope was determined. The majority of deduced gp60 amino acid sequence has no homology with any of the known alphaherpesvirus glycoproteins.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession number X 121209.     

Effects of luminal stimuli on polyamine metabolism in the small intestine of the rat: the role of enteric nerves

The aim of this study was to investigate to what extent polyamine metabolism in the small intestine of the rat is controlled by the enteric nervous system. Polyamine metabolism was followed by measuring the activity of ornithine decarboxylase (ODC) and in some instances also the content of polyamines (putrescine, spermidine and spermine). ODC activity in the intestine was increased when intraluminal pressure was increased and 3 h after placing cholera toxin in the intestinal lumen. Cholera toxin also increased the tissue putrescine content. Atropine or hexamethonium given i.v. did not influence the evoked changes of ODC activity. The pressure induced changes were not decreased by placing lidocaine on the serosal surface. On the other hand, the ODC activity of control segments were decreased by hexamethonium or atropine. The presence of glucose in the intestinal perfusate did not augment tissue ODC activity, neither did the heat stable enterotoxin from Escherichia coli (STa). It is concluded that the effect on polyamine metabolism evoked by luminal pressure or cholera toxin seems not to be mediated via nerves, while nerves seem to influence ODC activity during control conditions. The experiments with enterotoxins suggest that cAMP is the intracellular second messenger controlling intestinal ODC activity.     

Cross-linking of cell surface ganglioside GM1 induces the selective apoptosis of mature CD+ T lymphocytes

Gangliosides are glycosphingolipids found ubiquitously on thesurface of mammalian cells. They contain a ceramide tail thatis inserted into the membrane and exposed carbohydrate and sialicacid moleties. The non-toxic B subunit oligomer (EtxB) of Escherichiacoli heat-labile enterotoxin (Etx) is a potent immunogen invivo and has profound modulatory effects on EtxB-primed lymphocytesin vitro, properties which are dependent on its ability to bindto GM1 ganglioside receptors. Here, it is shown that cross-linkingGM1 by EtxB causes a differential effect on mature CD4⁺ andCD8⁺ T cells from lymph node cultures proliferating in responseto an unrelated antigen, ovalbumin. Addition of EtxB to suchcultures led to the complete depletion of CD8⁺ T cells comparedwith enhanced activation of CD4⁺ T cells [as measured by expressionof CD25 (IL-2R)]. By contrast, addition of a mutant EtxB, EtxB(G33D),which does not bind to GM1, failed to trigger CD8⁺ T cell depletion.When EtxB was added to isolated non-immune CD8⁺ lymphocytesrapid (12–18 h) alterations in nuclear morphology andthe appearance of sub-G₀/G₁ levels of DNA were induced; propertieswhich are characteristic of cells undergoing apoptosis. EtxB(G33D)failed to trigger apoptosis, indicating that the induction ofthe apoptotic signal was dependent on the binding of GM1. Thesefindings provide an insight into the potent immunogenicity andimmunomodulatory properties of E. coli enterotoxins as wellas heralding a novel method for the selective induction of apoptosisin mature CD8⁺ T lymphocytes.     

Cytopathogenic action ofEscherichia coli cells containing heterologous human type O(H) antigen on human cells in culture

The character of interaction between two enteropathogenic strains ofEscherichia coli of serotype 055K59 with human HeLa cells containing O(H) isoantigen was studied. On the addition of strainE. coli No. 5789, containing heterologous type O(H) antigen to a culture of HeLa cells, a cytopathogenic action was discovered on the third day of interaction in the presence of doses of bacterial cells of 2·10¹⁰, 2·10⁵, and 2·10⁴. A dose of 2·10³ bacterial cells ofE. coli did not give this effect. Strain No. 3827, not containing heterologous antigen of ABO type, had no cytopathogenic action in maximal, average, and small doses of bacterial cells. It is suggested that the cytopathogenic action of strain No. 5789 is connected with the presence of an antigen in this strain which is identical with the group antigen of the human cell culture studied.Research Laboratory of Experimental Immunobiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of medical Sciences of the USSR N. N. Zhukov-Verezhnikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 7, pp. 70–72, July, 1977.     

Interactions of the enantiomers of 3-O-methyldobutamine with α- and β-adrenoceptors in vitro

Summary The enantiomers of 3-O-methyldobutamine, a metabolite of dobutamine, were evaluated for their - and -adrenoceptor mediated effects in vitro in a variety of isolated organs and in radioligand binding studies. Neither enantiomer of 3-O-methyldobutamine possessed ₁-adrenoceptor agonist activity in isolated guinea pig aorta. However, both enantiomers of 3-O-methyldobutamine were competitive ₁-adrenoceptor antagonists, with the (+)-enantiomer being approximately 10-fold more potent than the (-)-enantiomer as assessed either in guinea pig aorta or by displacement of ³H-prazosin binding from ₁-adrenoceptors in rat cerebral cortex. The ₁-adrenoceptor blocking activity of (+)-3-O-methyldobutamine was relatively potent and corresponded to a pA₂ of 7.33 in guinea pig aorta and a-log K _i of 7.72 in radioligand binding studies. Neither enantiomer of 3-O-methyldobutamine possessed ₂-adrenoceptor agonist activity in field-stimulated guinea pig ileum. Although (+)-3-O-methyldobutamine weakly inhibited the twitch response in field-stimulated guinea pig ileum, the response was not blocked by the selective ₂-adrenoceptor antagonist, yohimbine, and was found to result from weak anticholinergic activity (pA₂=5.06). Neither enantiomer of 3-O-methyldobutamine possessed ₁-adrenoceptor agonist activity in guinea pig atria, however the (+)-enantiomer was a weak noncompetitive antagonist at ₁-adrenoceptors. In contrast, both enantiomers of 3-O-methyldobutamine were weak ₂-adrenoceptor agonists in rat uterus, however these weak effects were not highly stereoselective, which was also confirmed in radioligand binding studies. The results of the present study indicate that 3-O-methyldobutamine is a potent and highly selective ₁-adrenoceptor antagonist, with minimal activity at ₂-, ₁- and ₂-adrenoceptors. It is hypothesized that the potent ₁-adrenoceptor antagonist activity of 3-O-methyldobutamine, which resides predominantly in the (+)-enantiomer, may play a role in the hemodynamic effects of dobutamine, by contributing, in part, to the decrease in total peripheral vascular resistance observed following administration of dobutamine.     

Potentiation of central effects of L-dopa by an inhibitor of catechol-O-methyltransferase

Summary The effects of a COMT-inhibitor, U-0521, and a MAO-B-inhibitor, l-deprenyl, on L-dopa-induced circling behaviour were compared in 6-OHDA-lesioned rats. The actions of U-0521 and l-deprenyl on the anticataleptic effect of L-dopa were also studied. Both U-0521 and l-deprenyl were found to potentiate L-dopa-induced circling behaviour and anticataleptic effect of L-dopa. In both test systems the L-dopa potentiation of l-deprenyl was longer-lasting than that caused by U-0521. Thus inhibition of COMT, like inhibition of MAO, is able to enhance the central effects of L-dopa. This principle might be beneficial in the treatment of Parkinson's disease especially if COMT-inhibitors with greater performance can be developed.     

70. Ileorectostomie versus ileo-anale Anastomose mit Reservoir bei Colitis ulcerosa und Adenomatosis coli

Zusammenfassung Ca. 2000 Proktomucosektomien sind in den letzten Jahren durchgeführt worden als Alternative zur Proktocolektomie, aber auch zur Ileorectostomie bei AC und CU. Bei minimaler Operationsletalität ist die Rate der Frühkomplikationen (Ileus, Anastomoseninsuffizienz, Anastomosenstenose) nicht unbeträchtlich (> 10%). Die funktionellen Ergebnisse dagegen sind nach einer Phase der Adaptation vorwiegend gut. Die nicht unerheblichen Risiken der Ileorectostomie bei AC (Entartungsrate bis 20%) und bei CU (Entzündungsrezidiv 20–30%, sekundäre Entartung um 5%) haben die Proktomucosektomie an gröeren Zentren zu einem etablierten Verfahren werden lassen.