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PubMedDate not supplied

Blood glucose control determines the renal haemodynamic response to angiotensin converting enzyme inhibition in type 1 diabetes.

Elevation of glomerular filtration rate (GFR) is a feature of diabetes mellitus in humans and in animal models. Angiotensin II has been implicated as a mediator of GFR in diabetes. The acute effect of inhibition of angiotensin converting enzyme with captopril on renal haemodynamic and endocrine parameters was therefore studied in 14 normotensive male Type 1 diabetic patients, and the responses compared with those in five normal male control subjects. Following captopril 12.5 mg orally the diabetic patients exhibited an acute fall in GFR from 122 +/- 3.8 to 113 +/- 4.5 ml min-1 1.73-m-2 (p less than 0.02) and a rise in renal plasma flow (RPF) from 670 +/- 57 to 797 +/- 46 ml min-1 1.73-m-2 (p less than 0.01) which resulted in a fall in filtration. This did not occur in normal control subjects. Natriuresis occurred only in normal control subjects. There was no change in urinary excretion of PGE2 or kallikrein in either group but excretion of 6-keto-PGF1 alpha fell in the diabetic patients. There was a significant correlation between glycosylated haemoglobin and baseline RPF (rs = -0.79, p less than 0.001) and filtration fraction (rs = 0.83, p less than 0.001) that persisted when the change in these variables following captopril was analysed. Our results are compatible with the response to ACE inhibition in diabetic patients being secondary to inhibition of angiotensin II and suggest that this response may be related to blood glucose control.

Adult↗
PubMed1995

Sucrose-derived exopolymers have site-dependent roles in Streptococcus mutans-promoted dental decay.

We have constructed a panel of mutants of S. mutans V403 which are defective in one or more of the glucosyltransferase genes (gtfB, C or D) or the fructosyltransferase gene (ftf). These strains have been tested for virulence in a gnotobiotic rat caries model with reference to both buccal (smooth surface) and sulcal (pit and fissure) carious lesions. Our data suggest differing roles for degradable and non-degradable polymers at buccal and sulcal sites. Non-degradable polymers (made by products of the gtfB and C genes) contributed significantly to the severity of smooth surface lesions. However, our studies suggested their role in pit and fissure lesions was not as important as the role of degradable polymers. Specifically, a mutant deficient in the major insoluble glucan synthesizing activity (product of the gtfB gene) was 25% more cariogenic on sulcal surfaces than was the wild-type V403 strain. We propose that extracellular glucosyltransferases and fructosyltransferase compete for sucrose and that this competition influences pathogenicity at differing tooth sites.

Animals↗
PubMed2000

Metabolization of beta-(2,6)-linked fructose-oligosaccharides by different bifidobacteria.

Low-molecular-mass beta-(2,6)-linked fructose-oligosaccharides (beta-(2,6)-FOS) were examined as a new carbohydrate source for growth of bifidobacteria. beta-(2,6)-FOS were prepared from microbial high-molecular-mass levan by acid hydrolysis and refined by cation-exchange chromatography. (13)C-NMR spectroscopy confirmed the presence of predominantly beta-(2,6)-fructosyl linkages in the oligosaccharides. More than 80% beta-(2,6)-FOS was recovered after in vitro incubation with amylolytic and proteolytic enzymes, implying resistance to degradation in the upper intestinal tract. Bifidobacterium adolescentis, B. longum, B. breve, and B. pseudocatenulatum were studied in vitro for their ability to metabolize beta-(2,6)-FOS. Growth, decrease in pH, formation of short- chain fatty acids (lactate, acetate, formate) and degradation of beta-(2,6)-FOS were markedly different among species. B. adolescentis showed the best growth, produced the highest amounts of organic acids and metabolized both short- and long-chain beta-(2, 6)-FOS.

Bifidobacterium↗
PubMed1984

Comparison of plasma clearances of polyfructosan and 51Cr-EDTA in children.

Plasma clearances of polyfructosan and 51Cr-EDTA were determined in 38 children with renal diseases and in five healthy children in order to compare the values for the glomerular filtration rate (GFR) obtained by single injection procedures. Both one-compartment (Cr-EDTA-1) and two-compartment (Cr-EDTA-2) analyses were made of the isotope decay curve. The children were divided into two age groups: (a) 24 children below 6 years, and (b) 19 children between 8 and 16 years of age. In both groups Cr-EDTA-1 GFR and Cr-EDTA-2 GFR correlated significantly with polyfructosan GFR. The correlation coefficients, however, were somewhat lower in the younger (r = 0.74, r = 0.73) than in the older children (r = 0.91, r = 0.93). There were no significant differences between simultaneously obtained polyfructosan GFR and Cr-EDTA-2 GFR based on paired observations while Cr-EDTA-1 GFR was somewhat higher (16%) than the simultaneously obtained polyfructosan GFR. We conclude that estimates of GFR from polyfructosan and Cr-EDTA clearances based on two compartment analyses and single injection procedures are interchangeable.

Adolescent↗
PubMed1995

Identification of exopolysaccharides produced by fluorescent pseudomonads associated with commercial mushroom (Agaricus bisporus) production.

The acidic exopolysaccharides (EPSs) from 63 strains of mushroom production-associated fluorescent pseudomonads which were mucoid on Pseudomonas agar F medium (PAF) were isolated, partially purified, and characterized. The strains were originally isolated from discolored lesion which developed postharvest on mushroom (Agaricus bisporus) caps or from commercial lots of mushroom casing medium. An acidic galactoglucan, previously named marginalan, was produced by mucoid strains of the saprophyte Pseudomonas putida and the majority of mucoid strains of saprophytic P. fluorescens (biovars III and V) isolated from casing medium. One biovar II strain (J1) of P. fluorescens produced alginate, a copolymer of mannuronic and guluronic acids, and one strain (H13) produced an apparently unique EPS containing neutral and amino sugars. Of 10 strains of the pathogen "P. gingeri," the causal agent of mushroom ginger blotch, 8 gave mucoid growth on PAF. The "P. gingeri" EPS also was unique in containing both neutral sugar and glucuronic acid. Mucoid, weakly virulent strains of "P. reactans" produced either alginate or marginalan. All 10 strains of the pathogen P. tolaasii, the causal agent of brown blotch of mushrooms were nonnmucoid on PAF. Production of EPS by these 10 strains plus the 2 nonmucoid strains of "P. gingeri" also was negative on several additional solid media as well as in two broth media tested. The results support our previous studies indicating that fluorescent pseudomonads are a rich source of novel EPSs.

Alginates↗
PubMed1998

Cloning, nucleotide sequence, and expression in Escherichia coli of levansucrase genes from the plant pathogens Pseudomonas syringae pv. glycinea and P. syringae pv. phaseolicola.

Plant-pathogenic bacteria produce various extracellular polysaccharides (EPSs) which may function as virulence factors in diseases caused by these bacteria. The EPS levan is synthesized by the extracellular enzyme levansucrase in Pseudomonas syringae, Erwinia amylovora, and other bacterial species. The lsc genes encoding levansucrase from P. syringae pv. glycinea PG4180 and P. syringae pv. phaseolicola NCPPB 1321 were cloned, and their nucleotide sequences were determined. Heterologous expression of the lsc gene in Escherichia coli was found in four and two genomic library clones of strains PG4180 and NCPPB 1321, respectively. A 3. 0-kb PstI fragment common to all six clones conferred levan synthesis on E. coli when further subcloned. Nucleotide sequence analysis revealed a 1,248-bp open reading frame (ORF) derived from PG4180 and a 1,296-bp ORF derived from NCPPB 1321, which were both designated lsc. Both ORFs showed high homology to the E. amylovora and Zymomonas mobilis lsc genes at the nucleic acid and deduced amino acid sequence levels. Levansucrase was not secreted into the supernatant but was located in the periplasmic fraction of E. coli harboring the lsc gene. Expression of lsc was found to be dependent on the vector-based Plac promoter, indicating that the native promoter of lsc was not functional in E. coli. Insertion of an antibiotic resistance cassette in the lsc gene abolished levan synthesis in E. coli. A PCR screening with primers derived from lsc of P. syringae pv. glycinea PG4180 allowed the detection of this gene in a number of related bacteria.

Amino Acid Sequence↗
PubMed1978

Degradation of levan by Actinomyces viscosus.

Actinomyces viscosus ATCC 15987 was examined for its ability to hydrolyze its own levan. Washed whole cells and an ammonium sulfate fraction from cell-free culture fluids were shown to possess levan hydrolase activity. Analyses of reaction mixtures by gel filtration and thin-layer chromatography demonstrated that the product of levan hydrolysis was free fructose. The cell-associated and extracellular enzyme preparations also hydrolyzed inulin and the levans synthesized by Aerobacter levanicum and Bacillus subtilis. Growth of A. viscosus in media supplemented with 0.1% A. viscosus levan resulted in a 33-fold increase and a 7-fold increase in the specific activities of the respective extracellular and cell-associated enzymes when compared with those from 55 mM glucose cultures. Growth in the presence of 29.2 mM sucrose resulted in a 28-fold increase and a 5-fold increase in the specific activities of the respective enzymes when compared with those from the glucose cultures. The extracellular enzyme exhibited high activity over a wide pH range, with 87 and 89% of its pH 6.0 optimum activity at pH 5.0 and 7.0, respectively. The cell-associated enzyme also exhibited optimum activity at pH 6.0, but this was decreased to 10 and 20% at pH 5.0 and 7.0, respectively. Analysis for the presence of extracellular levan during growth of A. viscosus in sucrose broths demonstrated that peak levan concentrations occurred during the mid-exponential to late-exponential phase of growth followed by a rapid decline in extracellular levan as a result of levan hydrolase activity.

Actinomyces↗
PubMed1979

Specificity of coaggregation reactions between human oral streptococci and strains of Actinomyces viscosus or Actinomyces naeslundii.

Coaggregation reactions between actinomycete and streptococcal cells occurred frequently when human strains of Actinomyces viscosus or A. naeslundii were mixed with human isolates of Streptococcus sanguis or S. mitis, but were infrequent with other oral actinomycetes and streptococci. Two groups of actinomycetes and four groups of streptococci were defined by the patterns of their coaggregation reactions and by the ability of beta-linked galactosides (i.e., lactose) to reverse these reactions. Coaggregations occurred by one of the following three kinds to cell-cell interactions: (i) coaggregation that was blocked by heating the streptococcus but not the actinomycete and was not reversed by lactose; (ii) coaggregation that was blocked by heating the actinomycete but not the streptococcus and was reversed by lactose; and (iii) coaggregation that was blocked only by heating both cell types. The latter reaction was a combination of the first two since lactose reversed coaggregation between heated streptococci and unheated actinomycetes but did not reverse coaggregations between unheated streptococci and heated actinomycetes. Cells that could be heat inactivated also were inactivated by amino group acetylation or protease digestion, whereas cells that were unaffected by heat were not inactivated by these treatments. Coaggregation reactions of each kind were Ca2+ dependent and insensitive to dextranase treatment. These findings are consistent with the hypothesis that human strains of A. viscosus and A. naeslundii coaggregate with strains of S. sanguis and S. mitis by a system of specific cell surface interactions between protein or glycoprotein receptors on one cell type and carbohydrates on the other type.

Acetylation↗
PubMed1980

Anti-inulin [beta-(2 leads to 1)-linked polyfructose] and anti-grass levan [beta-(2 leads to 6)-linked polyfructose] antibody response in mice.

Anti-inulin [beta-(2 --> 1) polyfructosan Brucella abortus (InuBA)] and anti-grass levan [beta-(2 --> 6) polyfructosan] antibody responses in BALB/c and C57BL mice and in their F(1) and backcross progeny, as well as in immunoglobulin congenic and Bailey recombinant inbred strains derived from BALB/c and C57BL mice, were examined. The anti-inulin antibodies could accommodate both beta-(2 --> 1)- and beta-(2 --> 6)-linked polyfructosans, and 97% of the anti-inulin plaque-forming cells (PFC) from BALB/c mice expressed the cross-reactive idiotypes (InuIdX) shared by the BALB/c inulin- and levan-binding myeloma proteins. Of the C57BL mice, only 25% produced high anti-inulin response, and none exhibited the InuIdX of BALB/c anti-inulin antibodies. The percentages of InuIdX(+) anti-inulin PFC were also examined in other strains with high anti-inulin response. In C58 and AL mice, 80% of anti-inulin PFC were InuIdX(+), whereas in A/He and RIII mice, only 40% were InuIdX(+). All strains examined developed high anti-grass levan response, and the antibodies were specific for beta-(2 --> 6) structures and did not exhibit InuIdX. Comparison of the magnitude of the anti-inulin antibody titers in response to InuBA in BALB/c, C57BL, and their F(1) and backcross progeny, as well as in immunoglobulin congenic (i.e., B.C-8, BAB-14, and C.B-20) and recombinant inbred strains derived from BALB/c and C57BL mice, showed that all mice having the IgCH(a)(BALB/c) allotype gave high anti-inulin response. In addition to the InuIdX structural genes, the effects of allotype-linked or unlinked "regulatory" genes were also indicated by the lower anti-inulin response in B.C-8 and BAB-14 mice compared with BALB/c mice and the higher anti-inulin response in C.B-20 mice compared with C57BL mice. A multigene interaction in controlling the production of the anti-inulin antibodies was implicated.

Animals↗
PubMed1981

Rise in inulin-sensitive B cells during ontogeny can be prematurely stimulated by thymus-dependent and thymus-independent antigens.

We have shown that the delayed acquisition of competence in expression of an anti-inulin (IN) response by neonatal BALB/c mice is preceded by a natural increase in the frequency of IN-sensitive B cells between 3 to 5 weeks of life. Up until 3 weeks of age, BALB/c mice resemble adult germfree mice in their low frequency of IN-sensitive B cells (1 to 2/10(6) B cells). Thereafter, the population of IN-reactive B cells rises about 10-fold to the young adult level, without deliberate immunization. This naturally expanded population of IN-reactive cells has an isotype profile resembling populations arising after intentional priming with other antigens in that it contained a large proportion of cells which generated clones expressing immunoglobulin G and immunoglobulin A isotypes, often without detectable immunoglobulin M. The late rise in frequency of IN-sensitive precursors could be induced prematurely by deliberate priming at 3 days of age with either the thymus-dependent antigen IN-hemocyanin or the thymus-independent bacterial levan. However, no circulating anti-IN could be detected following this early administration of antigen. Thus, the delayed expression of anti-IN does not reflect an absence of B cells of the appropriate specificity which can be stimulated to divide by antigen but rather other events occurring subsequent to perinatal generation of antigen-sensitive cells. Our observations support a role for the beta2 --> 1 fructosyl group as an environmental determinant which selectively expands out preexisting antigen-sensitive B cells at 3 to 5 weeks of age and these include clonotypes which express the predominant anti-IN idiotypes.

Animals↗