Inhibitory activity of gut bacteria against Escherichia coli O157 mediated by dietary plant metabolites

Under both aerobic and anaerobic conditions, the growth of Escherichia coli O157 strain NCTC 12,900 was inhibited by the coumarins esculetin, umbelliferone and scopoletin, but not by the coumarin glycoside esculin. Esculin-hydrolysing bacteria from the rumen, the pig gut and the human gut inhibited growth of E. coli in an overlay-plate assay in the presence of esculin. The combined effect of esculetin and volatile fatty acids was greater than the effect of either factor alone suggesting that coumarin glycosides in the diet might reduce the growth or survival of E. coli O157 in the gut. Adding esculin to incubations of mixed rumen contents significantly reduced the survival of E. coli O157.

Effects of Coumarin and Sparteine on Attachment to Cellulose and Cellulolysis by Neocallimastix frontalis RE1

The plant secondary metabolites coumarin and sparteine reduced attachment to cellulose, cellulose solubilization, and the proportion of lactate in the fermentation products of the anaerobic fungus Neocallimastix frontalis RE1. Neither compound directly inhibited the endoglucanase or lactate dehydrogenase activities of cell extracts of the fungus.

Isolation and characteristics of a wheatbran-degrading Butyrivibrio from human faeces

Screening over 100 isolates from human faeces for cellulolytic activity led to the isolation of a weakly cellulolytic anaerobic, curved, motile bacterium which produced H2, lactate and butyrate from wheatbran. The mol% of G + C in the DNA was 39-42. These properties, together with the Gram-positive cell wall ultrastructure and SDS-PAGE profile, are consistent with the genus Butyrivibrio. The isolate is believed to be the most active wheatbran-degrading bacterium so far described.

Interactions between rumen bacterial strains during the degradation and utilization of the monosaccharides of barley straw cell-walls

Pure cultures and pair-combinations of strains representative of the rumen cellulolytic species Ruminococcus flavefaciens, Fibrobacter succinogenes and Butyrivibrio fibrisolvens were grown on cell-wall materials from barley straw. Of the pure cultures, R. flavefaciens solubilized straw most rapidly. The presence of B. fibrisolvens, which was unable to degrade straw extensively in pure culture, increased the solubilization of dry matter by R. flavefaciens and the solubilization of cell-wall carbohydrates by both R. flavefaciens and F. succinogenes. During fermentation, both R. flavefaciens and F. succinogenes released bound glucose and free and bound arabinose and xylose into solution. The accumulation of these sugars, especially arabinose and xylose, was greatly reduced in co-cultures containing B. fibrisolvens, suggesting that significant interspecies cross feeding of the products of hemicellulose hydrolysis (particularly soluble bound xylose released by F. succinogenes) occurs during straw degradation by mixed cultures containing this species.

Binding and degradation of lectins by components of rumen liquor

The binding of 15 different plant lectins to feed particles and microbes in rumen liquor, and their degradation were studied in vitro. The rate of degradation assessed from the label released when radioactive iodine-labelled lectins were incubated with rumen liquor conflicted with the rates calculated from measurements of the survival of the antigenic structure (immuno-rocket electrophoresis) or the biological function (haemagglutination) of the lectins. Thus solubilization of the radioactive label indicated that Concanavalin A (Con A), but not the soyabean agglutinin, SBA, or kidney bean phytohaemagglutinin, PHA-E3L, was stable to rumen proteolysis. In contrast, both SBA and PHA-E3L were shown by immuno-rocket electrophoresis or haemagglutination tests to be highly resistant to breakdown, while the degradation of Con A proceeded at a constant slow rate under the same conditions. This was in accord with the previously established general stability of lectins in the gut of single-stomach animals. Of the 15 lectins, SBA, favin (Vicia faba lectin) and Con A were bound by hay and the particle fraction of rumen liquor. This was, in part, specific and reversible in the presence of appropriate sugars. Most pure bacterial strains preferentially bound lectins with specificity for glucose/mannose (favin and Con A), while rumen fungi reacted with SBA. The level of binding was low with other lectins. However, inter-strain differences of lectin-binding were found in Selenomonas ruminantium and Ruminococcus flavefaciens. Clearly, as some lectins were not fully degraded in the rumen, they could be expected to depress the utilization of the diet not only in single-stomach animals but, possibly, also in ruminants.

The inhibition of fungal cellulolysis by cell-free preparations from ruminococci

The degradation of filter paper by the anaerobic fungus Neocallimastix frontalis strain RE1 was reduced by the addition of cell-free supernates from cultures of Ruminococcus albus strain J6 and R. flavefaciens strains 17 and 007. Fungal uptake of, and growth on, glucose was not affected. After gel permeation and anion exchange chromatography, inhibitory activity towards fungal cellulolysis was recovered in a fraction from strain 17 that contained at least five negatively charged polypeptide components, molecular mass 45-68 kDa, on SDS-PAGE.

Prevention of fungal colonization and digestion of cellulose by the addition of methylcellulose

When the attachment of cellulolytic rumen fungi to cellulose is blocked by the addition of methylcellulose, cellulose digestion is entirely inhibited. Even after these fungi have colonized and penetrated the cellulosic fibers of filter paper, the addition of methylcellulose effectively halts cellulose digestion. This effect of methylcellulose is accompanied by the complete inhibition of fungal attachment to cellulose fibers; the addition of methylcellulose does not affect the growth of these organisms on soluble substrates. We conclude that fungal cellulose digestion, like bacterial cellulose digestion, requires the spatial juxtaposition of the cellulolytic organism and its insoluble substrate. The simultaneous inhibition of both attachment and digestion by the same inhibitor suggests that these two processes are functionally linked in the fungi.

The properties of forms of Ruminococcus flavefaciens which differ in their ability to degrade cotton cellulose

Two mutant strains of Ruminococcus flavefaciens strain 007 that differ in their ability to hydrolyse cotton fibres have been shown also to differ in their cell-surface topology, in that the cotton degrading form possessed larger and more protuberant cell surface structures. The strains had similar CMCase, cellobiosidase and beta-glucosidase activities. The results indicate the importance of cell-surface properties in cotton degradation by R. flavefaciens.

Safety and efficacy of topical minoxidil in the management of androgenetic alopecia

Of 149 subjects with androgenetic alopecia, 102 completed 1 year of a double-blind, randomized study comparing 2% minoxidil and 3% minoxidil solutions for safety and efficacy. One third of the subjects used a vehicle placebo for the first 4 months and then switched to 3% minoxidil. At 12 months the 2% minoxidil group switched to a 3% solution. During months 5 to 12 a steady increase in terminal hair counts occurred to an equal degree within the 2% and 3% minoxidil groups and the 3% treatment group switched from placebo. Total hair counts at 12 months increased from a baseline mean of 63.5 to 180.6 in the 2% treatment group, from 61.0 to 179.9 in the 3% group, and from 65.0 to 191.1 in the placebo to 3% crossover group. Although all 102 subjects completing 12 months of the study thought that visible hair growth had resulted, 89 were considered by the investigators to have visible growth. Dense hair growth, defined as hair long enough to cut or comb, was present in 48 subjects by their own evaluation and in 33 subjects by investigator evaluation. There were no serious side effects. Two instances of allergic contact dermatitis and four of pruritus were attributed to use of the drug. Two individuals complained of impotence, which disappeared within a few days of discontinuation of topical minoxidil. This effect has not been reported during the use of minoxidil in its oral form (Loniten) for the treatment of hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of ammonia treatment on the solubilization of straw and the growth of cellulolytic rumen bacteria

Pre-treatment of straw with anhydrous ammonia increased its susceptibility to solubilization by the predominant cellulolytic bacteria from the rumen, Bacteroides succinogenes, Ruminococcus albus and R. flavefaciens. Ammonia treatment also increased the production of microbial protein and fermentation products by all three species. Scanning electron microscope observations of straw during digestion suggested that the attack of straw by these bacteria was accompanied by the formation of substantial numbers of adherent microcolonies.

Clindamycin phosphate used in combination with tretinoin in the treatment of acne

Sixty-four patients with acne were studied to evaluate the irritancy, tolerance, and systemic absorption of topical 1% clindamycin phosphate when combined with tretinoin gel 0.025% as compared to either agent alone. All these treatment regimens were effective and well-tolerated. Clindamycin alone was less irritating than tretinoin alone or tretinoin combined with clindamycin. The combination treatment produced fewer complaints from patients than tretinoin alone. No systemic absorption of clindamycin was detected after two weeks and eight weeks of usage.

Benzoyl peroxide reactions in an acne study group

Benzoyl peroxide patch testing was performed on 60 young adults who had participated in a double-blind acne study. 25% of those who had used a benzoyl peroxide product showed reactivity of +1 or greater (on a 0--3 scale). None of these individuals demonstrated symptoms suggestive of irritancy or allergy greater than those who did not have positive patch tests and who were on the same treatment program. The positive patch tests did not correlate with acne treatment responses. 2 of 44 individuals in the acne study group developed clinical allergy and had dramatically positive patch tests, while the majority of individuals with positive patch tests could use products containing benzoyl peroxide daily without significant adverse effects.