Browsing by Author "CALDERON, I"

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    ANTIBODIES TO PORIN ANTIGENS OF SALMONELLA-TYPHI INDUCED DURING TYPHOID INFECTION IN HUMANS
    (1986) CALDERON, I; LOBOS, SR; ROJAS, HA; PALOMINO, C; RODRIGUEZ, LH; MORA, GC
    Immunoglobulin G (IgG-)- and IgM-specific antibody titers against Salmonella typhi Ty2 porins have been measured in 30 paired typhoid sera by enzyme-linked immunosorbent assay. These studies have found that IgG serum titers of acute and convalescent sera were 625 and 5,000 times higher, respectively than the control serum titers. The same typhoid sera were titrated with S. typhi Ty2 flagellin and S. typhi lipopolysaccharide. The titers against these antigens were considerably lower than those against the porins. The highest IgM-specific titer has also been found against porins in convalescent-phase sera. However, the largest increase in IgM-specific titer compared with the control group titer was obtained against flagellin during the acute phase of typhoid. The lowest increases in antibody titer were obtained with the IgM-specific anti-lipopolysaccharide in both types of sera. This may be because many normal individuals in endemic areas already have IgM titers against lipopolysaccharide. This study has provided good evidence that porins are excellent antigens and that IgG-specific antiporin titers may be of diagnostic value in typhoid infections in endemic areas.
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    CLINICAL ISOLATE OF A PORINLESS SALMONELLA-TYPHI RESISTANT TO HIGH-LEVELS OF CHLORAMPHENICOL
    (1990) TORO, CS; LOBOS, SR; CALDERON, I; RODRIGUEZ, M; MORA, GC
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    DEGRADATION OF DIARYLETHANE STRUCTURES BY PSEUDOMONAS-FLUORESCENS BIOVAR-I
    (1988) GONZALEZ, B; OLAVE, I; CALDERON, I; VICUNA, R
    Pseudomonas fluorescens biovar I was isolated from a pulp mill effluent based on its ability to grow on synthetic media containing 1,2-diarylethane structures as the sole carbon and energy source. Analysis of samples taken from cultures of this strain in benzoin or 4,4''-dimethoxybenzoin (anisoin), showed that cleavage between the two aliphatic carbons takes place prior to ring fission. Intermonomeric cleavage was also obtained with crude extracts. Substrates of this reaction were only those 1,2-diarylethane compounds that supported growth of the bacterium. The purification and partial characterization of an enzyme that catalyzes the NADH-dependent reduction of the carbonyl group of benzoin and anisoin is also reported.
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    IMMUNOGENIC CAPACITY OF RIBOSOMES OF SALMONELLA-TYPHI INTERFERED WITH BY A FLAGELLIN-LIKE MATERIAL CONTAMINANT
    (1978) COFRE, G; CALDERON, I; MORA, GC
    The double-immunodiffusion technique and sodium dodecyl sulfate-polyacrylamide electrophoresis were used to demonstrate the presence of flagellin-like material strongly attached to ribosomes of S. typhi Ty 2. This flagellin-like material contaminating the ribosome preparation interfers with the induction of [rabbit] antiribosome serum, promoting the formation of antisera reacting either only with flagellin or in some cases with flagellin and ribosomes, but giving a very weak reaction with the latter. The interference is also observed when purified ribosomes from a nonflagellated mutant of S. typhi (S. typhi O-901) mixed with purified S. typhi Ty 2 flagellin are utilized as antigens. The antirosome sera obtained with ribosomes from S. typhi O-901 have a considerably higher titer than those that are interfered with. These sera were able to react with ribosomes obtained from several related species and did not react with flagella-derived flagellin of S. typhi Ty 2.
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    MICROBIAL AND BIOCHEMICAL-CHARACTERIZATION OF A BACTERIAL CONSORTIUM ISOLATED FROM DECAYING WOOD BY GROWTH ON A BETA-O-4 LIGNIN-RELATED DIMERIC COMPOUND
    (1992) CESPEDES, R; SALAS, L; CALDERON, I; GONZALES, B; VICUNA, R
    As an approach to evaluate the contribution of bacteria to lignin degradation in wood, we have chosen to study these microorganisms in the natural wood decay ecosystem known as Palo Podrido. Initially, the characterization of bacteria able to metabolize lignin-related compounds present in samples of Palo Podrido was undertaken. For their isolation, minimal salt media containing lignin dimers of either the arylglycerol-beta-aryl ether (beta-O-4) or 1,2-diarylpropane (beta-1) types as the only source of carbon and energy were inoculated with various wood samples exhibiting different degrees of decay. The beta-1 dimers used failed to support bacterial growth. However, three bacterial consortia able to consume quantitatively the beta-O-4 model 1-[3,4-dimethoxyphenyl]-2-[2-methoxyphenoxy]-3-hydroxypropanone (compound I) were isolated. One of these was further characterized. It is composed of eight strains belonging to the families of Streptomycetaceae, Dermatophilaceae and Actinoplanaceae. HPLC and GC-MS analyses revealed that the consortium utilizes two pathways to degrade beta-O-4 dimers, both involving direct cleavage of the ether linkage. The formation of a novel C6-C3 degradation intermediate is described. Some metabolic properties of each strain, as well as those of the intact consortium, are also reported.
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    THE HEMOLYTIC EFFECT OF SALMONELLA-TYPHI TY-2 PORINS
    (1984) CALDERON, I; LOBOS, SR; MORA, GC
    Two outer membrane proteins of S. typhi Ty 2 were extensively co-purified. According to their migration in dodecylsulfate/polyacrylamide gel electrophoresis and solubility characteristics, these proteins are homologous to the 35-kDa (kilodalton) and 36-kDa porins found in S. typhimurium. A porin homologous to the 34-kDa one was not found in S. typhi Ty 2. A critical step in the purification of porins is heating at 100.degree. C in 2% sodium dodecyl sulfate before Sephadex gel filtration. The absence of detergent in aqueous suspensions enhances porin aggregation, these aggregations inducing human red cell lysis. Porins obtained by an alternative procedure consisting of heating at 60.degree. C instead of 100.degree. C were also hemolytic. Using nanomolar concentration of porins a strong influence of temperature on the hemolytic effect was observed. Porin-induced hemolysis was inhibited with anti-porin serum and by treatment with phenylglyoxal, which reacts with the arginine residues of proteins. The membrane-disrupting ability of porin aggregates might explain some pathogenic characteristics of gram-negative bacterial infections.