Specificity of rabbit antisera against the rough lipopolysaccharide of Salmonella minnesota strain R7 (chemotype Rd1P-)

Rabbit polyclonal antibodies against the lipopolysaccharide (LPS) of the Rd1P- mutant strain R7 of Salmonella minnesota were serologically characterized using R7 LPS, dephosphorylated LPS, deacylated LPS, deacylated, dephosphorylated and reduced LPS, and synthetic partial structures. The latter comprised partial structures of the core region of Rd1P- LPS bound to the beta 1-->6-linked glucosamine dissacharide with two amide-linked 3-hydroxytetradecanoic acid residues or artificial glycoconjugates comprised of the synthetic oligosaccharides coupled to bovine serum albumin. Using a passive hemolysis and an enzyme immunoassay, absorption and inhibition experiments, the antibody specificites present could be determined. One group of antibodies required components of the core region and the phosphorylated glucosamine disaccharide of the lipid A moiety for binding. The majority of phosphate-independent antibodies was directed against the trisaccharide L-glycero-alpha-D-manno-heptopyranose(1-->3)- L-glycero-alpha-D-manno-heptopyranose(1-->5)3-deoxy-D-manno-oct ulo sonic acid. Antibodies against the 1-->3- and 1-->7-linked heptose disaccharides and against a single heptose were also detected, however, with low titers. No antibodies were found which required the presence of fatty acids.     

Chemical structure of lipid A from Helicobacter pylori strain 206-1 lipopolysaccharide

The chemical structure of a novel lipid A, which was obtained as a major component from lipopolysaccharide of Helicobacter pylori strain 206-1, was determined to be a glucosamine beta(1-6) disaccharide 1-(2-aminoethyl)phosphate acylated by (R)-3-hydroxyoctadecanoic acid and (R)-3-(octadecanoyloxy)octadecanoic acid at the 2- and 2'-position, respectively. The absence of a phosphoryl group at the 4'-position and fatty acyl groups at the 3- and 3'-position, and the stoichiometric presence of 2-aminoethyl phosphate at the 1-position are unique features, distinguishing it from the lipid A of enterobacteria.     

Frequency and drug sensitivity of "Klebsiella oxytoca" in human clinical material (author's transl)

962 Klebsiella strains were isolated from a total of 15422 clinical samples. 782 of these were characterized as the species Klebsiella pneumoniae, 170 as "Klebsiella oxytoca" and 10 as Klebsiella ozaenae. 95 of the Klebsiella oxytoca strains originated from samples of the respiratory tract, 13 from purulent materials, 1 from blood and 61 from urine samples. Among further biochemical criteria indole formation, lacking gas formation at 45 degrees C in lactose peptone water medium and delayed gelatine liquefaction were used to differentiate Klebsiella oxytoca from other enterobacteriaceae. In addition the drug resistance patterns were determined.     

Centrally infused galanin-(1-15) but not galanin-(1-29) reduces the baroreceptor reflex sensitivity in the rat

It has been demonstrated previously that central administration of the N-terminal galanin fragment (1-15) elicits hypertension and tachycardia and antagonizes the hypotensive effect of the parent molecule galanin-(1-29). In order to further clarify the role of galanin in central cardiovascular control, the possible modulation of the baroreceptor reflex by both galanin molecules has been studied. Different groups of rats were injected in the lateral ventricle with subthreshold doses of galanin-(1-15) (0.1 nmol/rat, or 0.3 nmol/rat), with subthreshold doses of galanin-(1-29) (0.1 nmol/rat, and 0.3 nmol/rat) or with an effective dose of galanin-(1-29) (3.0 nmol/rat). The baroreceptor reflex was elicited by intravenous injections of different doses of L-phenylephrine before and after the intraventricular administration of galanin peptides. The changes of the bradycardic responses after galanin peptide injections as well as the modifications of the baroreceptor reflex sensitivity were evaluated. Intraventricular injections of galanin-(1-15) significantly inhibited the reflex bradycardia elicited by intravenous L-phenylephrine and thus decreased the baroreceptor sensitivity. However, neither subthreshold doses of galanin-(1-29) nor its effective dose were able to modulate these cardiovascular responses. From these data it may be suggested that the galanin fragment (1-15) plays a more important role in central cardiovascular regulation than galanin-(1-29), possibly acting on a specific receptor subtype which exclusively recognizes N-terminal fragments of galanin, and exists on cardiovascular areas of the central nervous system.     

Crystal structure of TNF-alpha mutant R31D with greater affinity for receptor R1 compared with R2

Crystal structures have been determined of recombinant human tumor necrosis factor-alpha (TNF-alpha) and its R31D mutant that preferentially binds to TNF receptor R1 with more than seven times the relative affinity of binding to receptor R2. Crystals of the wild-type TNF were of space group P4(1)2(1)2 and had unit cell dimensions of a = b = 94.7 and c = 117.4 A. Refinement of the structure gave an R-factor of 22.3% at 2.5 A resolution. The crystals of TNF R31D mutant diffracted to 2.3 A resolution, and were of identical space group to the wild type with unit cell dimensions of a = b = 95.4 and c = 116.2 A, and the structure was refined to an R-factor of 21.8%. The trimer structures of the wild-type and mutant TNF were similar with a root mean square (r.m.s.) deviation of 0.56 A for Calpha atoms; however, the subunits within each trimer were more variable with an average r.m.s. deviation of 1.00 A on Calpha atoms for pairwise comparison of subunits. Model complexes of TNF with receptors R1 and R2 have been used to predict TNF-receptor interactions. Arg31 in all three subunits of wild-type TNF is predicted to form an ionic interaction with the equivalent glutamic acid in both receptors R1 and R2. Asp31 of the TNF R31D mutant is predicted to interact differently with the two receptors. The side chain of Asp31 in two subunits of the TNF mutant is predicted to form hydrogen bond interactions with Ser59 or Cys70 of R1, while it has no predicted interactions with R2. The loss of three strong ionic interactions of Arg31 and the electrostatic repulsion of Asp31 with Glu in the receptors is consistent with the reduced binding of the R31D mutant to both receptors relative to wild-type TNF. The replacement of these ionic interactions by two weaker hydrogen bond interactions between Asp31 of the R31D mutant and R1, compared with no interactions with R2, is in agreement with the observed preferential binding of the R31D mutant to R1 over R2. Analysis of the structure and function of receptor-discriminating mutants of TNF will help understand the biological role of TNF and facilitate its use as an antitumor agent.     

The structure of R(1-x)Ga2(1- x)(0 < x < 0.33) and its relation to RGa6 (R = Rare Earth Element) and Ga

X-ray diffraction studies were used to investigate the wide solubility range of Ga in RGa₂ type compounds observed in several systems of light rare earth metals (= R) with Ga. A model, based on pairwise substitution of R atoms by Ga atoms, is suggested to explain the observed wide solubility. Using this model it is possible to explain the change in lattice parameters of the ε phase having the formula R(_1-x)Ga₂(_1+x). The structural relationships among the phases RGa₂, R(_1-x)Ga₂(_1+x,RGa₆, and pure Ga are delineated, and the common feature of these phases which belong to widely different crystal systems is shown.     

The structure of R(1-x)Ga2(1- x)(0 < x < 0.33) and its relation to RGa6 (R = Rare Earth Element) and Ga

X-ray diffraction studies were used to investigate the wide solubility range of Ga in RGa₂ type compounds observed in several systems of light rare earth metals (= R) with Ga. A model, based on pairwise substitution of R atoms by Ga atoms, is suggested to explain the observed wide solubility. Using this model it is possible to explain the change in lattice parameters of the ε phase having the formula R(_1-x)Ga₂(_1+x). The structural relationships among the phases RGa₂, R(_1-x)Ga₂(_1+x,RGa₆, and pure Ga are delineated, and the common feature of these phases which belong to widely different crystal systems is shown.     

The inductive immunosuppressive activity of the lipopolysaccharide from Shigella sonnei R forms]

BACKGROUND AND AIMS: The hypothesis of an emotional component in asthma has been put forward since antiquity. It is currently explored using a psychodynamic, cognitive-behavioural and systemic-relational approach. This study, carried out using a psychodynamic approach, aimed to identify the psychological aspects of recurrent asthmatic attacks in childhood. METHODS: The study examined 20 subjects, aged between 9 months and 7 years and 11 months, attending the Pneumological Division of the Ospedale Infantile in Turin. The study consisted of the collection of social and personal data regarding the family and clinical and medical history; a semi-structured interview with the mothers, discussed as part of individual supervision regarding the mother-child relationship and the emotive reactions to an asthma attack. RESULTS: Although all subjects had an early onset of manifest asthma, ascertained allergic pathogenesis was only revealed in 30% of children. All cases revealed a lacking and/or conflictual quality in the mother-child relationship, as well as the young patient's difficulty in growing up, implying the acquisition of gradual autonomy. CONCLUSIONS: The authors emphasise the need to focus greater attention on the emotive situation of the child and its parents, in particular those aspects regarding the quality of life under the influence of disease.     

(1S,2R)-D-erythro-2-(N-myristoylamino)-1-phenyl-1-propanol as an inhibitor of ceramidase

In this study, we have examined the cellular and biochemical activities of the ceramide analog (1S,2R)-D-erythro-2-(N-myristoylamino)-1-phenyl-1-propanol (D-erythro-MAPP). Addition of 5 microM D-e-MAPP to HL-60 human promyelocytic leukemia cells resulted in a concentration- and time-dependent growth suppression accompanied by an arrest in the G0/G1 phase of the cell cycle; thus mimicking the action of exogenous ceramides. Its enantiomer L-e-MAPP was without effect. Two lines of evidence suggested that D-e-MAPP may not function as a direct analog of ceramide. First, D-e-MAPP possesses a stereochemical configuration opposite to that of D-erythro-ceramide. Second, D-e-MAPP failed to activate ceramide-activated protein phosphatase in vitro. Therefore, we examined if D-e-MAPP functioned indirectly by modulating endogenous ceramide levels. The addition of D-e-MAPP to cells, but not L-e-MAPP, caused a time- and concentration-dependent elevation in endogenous ceramide levels reaching greater than 3-fold over baseline following 24 h of treatment. Both D-e-MAPP and L-e-MAPP underwent similar uptake by HL-60 cells. D-e-MAPP was poorly metabolized, and remained intact in cells, whereas L-e-MAPP underwent a time- and concentration-dependent metabolism; primarily through N-deacylation. In vitro, L-e-MAPP was metabolized by alkaline ceremidase to an extent similar to that seen with C16-ceramide. D-e-MAPP was not metabolized. Instead, D-e-MAPP inhibited alkaline ceramidase activity in vitro with an IC50 of 1-5 microM. D-e-MAPP did not modulate the activity of other ceramide metabolizing enzymes in vitro or in cells, and it was a poor inhibitor of acid ceramidase (IC50>500 microM). Finally, D-e-MAPP inhibited the metabolism of L-e-MAPP in cells. These studies demonstrate that D-e-MAPP functions as an inhibitor of alkaline ceramidase in vitro and in cells resulting in elevation in endogenous levels of ceramide with the consequent biologic effects of growth suppression and cell cycle arrest. These studies point to an important role for ceramidases in the regulation of endogenous levels of ceramide.