Prevention of artificial dental plaque formation in vitro by plant extracts.

AIMS: A number of previous studies have shown that plant extracts can inhibit formation of dental plaque. The ability of extracts of Rosmarinus officianalis L., Salvia officianalis L., unfermented cocoa, red grape seed and green tea to inhibit plaque bacteria, glucosyltransferase activity, glucan and plaque formation in an in vitro model using bovine teeth was examined. METHODS AND RESULTS: The antimicrobial activity of the plant extracts against oral bacteria was determined using a standard susceptibility agar dilution technique. Inhibition of growth and acid production from glucose and sucrose by Streptococcus mutans in liquid culture was investigated. Prevention of plaque formation on bovine teeth initiated by Strep. mutans was studied using an artificial mouth. The plant extracts inhibited the growth of oral bacteria and prevented acid production by Strep. mutans. Extracts inhibited glucosyltransferase activity and glucan production and inhibited adhesion to glass. Extracts of R. officianalis L. and S. officianalis L. at 0·25 mg ml(-1) reduced plaque growth by >80%. Green tea extract completely inhibited plaque formation but resulted in a greenish discolouration of the teeth which could not be removed by scrubbing. CONCLUSIONS: The plant extracts, particularly those from R. officianalis L. and S. officianalis L., inhibited glucosyltranferase activity, glucan production and plaque formation in vitro. SIGNIFICANCE AND IMPACT OF THE STUDY: The results suggest that the extracts of R. officianalis L. and S. officianalis L. may be useful as antiplaque agents in foods and dental preparations. Bovine teeth can be used as an alternative to hydroxyapatite for studies of plaque formation, but they need to be carefully sterilized before use.

The antibacterial activity of plant extracts containing polyphenols against Streptococcus mutans.

The minimum inhibitory concentrations (MIC) of commercially available and 70% aqueous propanone (P70) extracts from plants chosen for polyphenol content on Streptococcus mutans and other bacteria were determined using a standard susceptibility agar dilution technique to investigate their potential use as anticariogenic agents. The effects on adhesion of S. mutans to glass were also studied. The lowest MICs were for the P70 extracts of red grape skin (0.5 mg ml(-1)) and green tea and sloe berry skin (2 mg ml(-1)). The commercial extracts generally had a lower activity with a minimum MIC of 2 mg ml(-1) for tea extracts, grape seed extracts and Pynogenol (extract of maritime pine). All other extracts had MICs of > or = 4 mg ml(-1). Unfermented cocoa had greater antimicrobial activity than fermented cocoa and the activity of the fractionated extract increased with the extent of epicatechin polymerization. Epicatechin polymer had an MIC of 1 mg ml(-1) and an MBC of 64 mg ml(-1). Selected extracts were tested against other oral bacteria and showed activity against gram-positive organisms. P70 extracts of unfermented cocoa, epicatechin polymer fraction, green tea and red grape seed were bacteriostatic and prevented acid production when added at the MIC to cultures of S. mutans grown in a chemically defined medium supplemented with either glucose or sucrose. There was a reduction in viability which was greater when added to washed cells, but there were some viable cells after 24 h. The extracts also reduced adherence of S. mutans to glass.

Evaluation of Chromocult coliform agar for the detection and enumeration of Enterobacteriaceae from faecal samples from healthy subjects.

The purpose of this study was to examine the use of Chromocult agar medium for isolation and enumeration of Enterobacteriaceae from human faecal samples, to compare it to MacConkey agar and to evaluate its usefulness as a possible alternative selective medium in human faecal studies. The medium was shown to be effective in identifying Escherichia coli and coliforms in faeces without the need for extensive accompanying biochemical tests for confirmation of identity. A positive correlation (r=0.86) was found between the recovery of Enterobacteriaceae on the two media, and no significant difference (P>0.05) between overall mean bacterial counts for the whole study group or at different intervals of faecal collection were observed. Chromocult agar is an effective replacement for MacConkey agar in human faecal studies and has the advantage of differentiating E. coli from other coliforms.

Comparative studies on Asian and Caucasian children. 1: Growth.

The growth of children whose parents originated from the Indian sub-continent (Asians) was compared with that of indigenous, white children in Rochdale (Caucasians) in a longitudinal study during the first 2 years of life. Reference was made to growth standards currently used in the UK and a small cross-sectional growth study was also carried out on related infants living in Pakistan. With the exception of birthweight, analysis of variance revealed few significant differences in individual growth parameters between the two populations living in the UK.

Comparative studies on Asian and Caucasian children. 2: Nutrition, feeding practices and health.

The growth of children whose parents originated from the Indian subcontinent (Asians) and of indigenous, white children in Rochdale (Caucasians) has been related to dietary intake which was estimated by 3-day weighed intakes during a longitudinal study at 3, 6, 9, 12 and 24 months of age. The use of human milk vis-à-vis infant milk formulas, the age of introduction of solid food and the effect of other environmental factors were also evaluated. Multiple regression analysis revealed the effects of diet per se on growth to be fairly minimal; a maximum of 28 per cent of the variation in growth could be explained by diet and the few individual nutrients significantly correlated with a growth index were not consistent.

The comparative gastrointestinal responses of children and adults following consumption of sweets formulated with sucrose, isomalt and lycasin HBC.

OBJECTIVES: To determine the gastrointestinal responses of children and adults following consumption of sucrose, isomalt and lycasin HBC and to compare these at two different dose levels in adults. DESIGN: Both studies were randomised, double-blind, cross-over designs. SUBJECTS: Fifty-one children aged 6-9 y were recruited from primary schools in the Salford area of Greater Manchester. Forty-eight children completed the study. Fifty healthy adult volunteers aged 18-24 y were recruited from the student population of the University of Salford. All subjects completed the study. INTERVENTIONS: Children consumed either 25 g of sucrose, isomalt or lycasin HBC and adults 25 and 40 g in hard boiled sweets per day for two consecutive test days. Test periods of 2 days were separated by 7 day washout periods. Children consumed sweets throughout test days and adults in no less than 30 min but no more than 90 min. Subjects reported the prevalence and magnitude of flatulence, borborygmi, bloating, colic, bowel movements and watery faeces. RESULTS: Consumption of 25 g isomalt provoked a mild laxative effect in children but not in adults. Consumption of 25 g isomalt significantly increased the prevalence and magnitude of gastrointestinal responses in both children and adults. Consumption of 25 g lycasin HBC significantly increased borborygml in children and adults but no other gastrointestinal responses. Consumption of 40 g lycasin HBC or isomalt by adults significantly increased the mean frequency of bowel movements and the number of subjects passing watery faeces. In adults, 40 g isomalt and lycasin HBC provoked significantly more gastrointestinal responses compared to 25 g of either product. CONCLUSIONS: Consumption of 25 g lycasin HBC does not provoke an unacceptable laxative effect or gastrointestinal response in children or adults compared to 25 g isomalt, which is associated with a mild laxative effect and increase in gastrointestinal responses. In adults gastrointestinal responses following consumption of products were found to be dose dependent.

Dose-related gastrointestinal response to the ingestion of either isomalt, lactitol or maltitol in milk chocolate.

OBJECTIVES: To determine whether there were differences between different polyols (sugar alcohols) in terms of their ability to stimulate intolerance symptoms when consumed in milk chocolate. Also to discover whether symptomatology can be related to the dose of polyol ingested. DESIGN: The study was of a randomised double-blind cross-over design. SUBJECTS: 59 healthy volunteers aged 18-24 years were recruited from the student population of the University of Salford. All subjects successfully completed the trial. INTERVENTIONS: Subjects ingested 100 g milk chocolate containing 40 g bulk sweetner as either sucrose, isomalt, lactitol or maltitol or a mixture (10:30 w/w) of sucrose and isomalt, sucrose and lactitol or sucrose and maltitol. Each bar was taken as breakfast on one day with following products consumed at 1-week intervals. Subjects reported the incidence and severity of the symptoms of flatulence, borborygms, colic, motion frequency and loose stools. RESULTS: The ingestion of 30 g or 40 g lactitol resulted in a significant increase in the incidence and severity of all symptoms examined compared to reactions after the consumption of standard sucrose-containing chocolate (P <0.01). Similarly, 40 g isomalt led to an increased incidence of all symptoms, including mild laxation (P <0.01), but unlike lactitol none was rated as being severe. A reduction in isomalt to 30 g was marked by increased tolerance with evidence of only mild borborygms (P <0.01), mild flatulence, colic, and laxation (P <0.05), with no increase in motion frequency (P <0.35). Ingestion of 40 g maltitol caused less intolerance than 40 g isomalt, with evidence of only flatulence, borborygms and colic (P <0.01), symptoms being rated as only mild. A reduction to 30 g led to a decrease in all symptoms except mild flatulence. Maltitol did not have any laxative effect when ingested at either 30 g (P = 0.32) or 40 g (P = 0.13) per day. CONCLUSIONS: This work has shown that there are significant differences in the reporting of gastrointestinal symptomatology following the consumption of isomalt, lactitol and maltitol incorporated into milk chocolate. However, with all three polyols the incidence and severity of symptomatology was dose dependent.

The occurrence of the trematode Plagiorchis muris in the wood mouse Apodemus sylvaticus in North Yorkshire, UK.

Wood mice Apodemus sylvaticus were trapped each September over a 13-year period, from 1993 to 2005, in a wooded area adjacent to Malham Tarn, Yorkshire, UK. Plagiorchis muris was found to be the dominant intestinal trematode and occurred in every year of sampling, with an overall prevalence of 16.9%. This appears to be the first record of P. muris in A. sylvaticus within the UK. The mean worm burden was 2.03 and the distribution of the parasite within mice was typically overdispersed. No difference in prevalence relative to host sex was evident although there was a higher prevalence of 21.9% in larger older mice compared with 9.1% in juveniles, which probably relates to a greater foraging activity in older mice. Annual prevalence values of P. muris infections varied significantly over the study period with higher prevalences being associated with years with a high spring/summer rainfall. The second intermediate hosts for P. muris include a variety of aquatic insect larvae and it is likely that the higher rainfall may result in the occurrence of temporary water bodies suitable for the development of insect larvae.

Filariasis: nutritional interactions in human and animal hosts.

Vector-borne nematodes of the Order Filarioidea produce chronic, debilitating human infections which are usually nonfatal but are associated with a high degree of severe morbidity. Weight loss often accompanies infection and is probably a consequence of the increased energy cost associated with filarial fever, lymphangitis and lymphadenitis. In onchocerciasis, weight loss is associated with heavy worm loads as assessed by abundant nodules and large numbers of skin microfilariae. Experimental infections using rodent filariae have confirmed these observations and have also shown that low protein diets render hosts more susceptible to infection; nevertheless, parasite growth and embryogenesis is retarded in stunted female worms from protein deficient animals. In the absence of appropriate evidence, studies of experimental filariasis suggest that human protein-energy malnutrition may delay the development of stage-specific acquired immunity with a corresponding prolongation of patency. Epidemiological and experimental evidence shows that filarial nematodes acquire certain nutrients directly from their hosts. Of major importance in this respect is vitamin A which is taken up preferentially by human and rodent filariae; in humans, symptoms of hypovitaminosis A often accompany infection and could be an aggravating factor in onchocerciasis. Filariae also appear to require other specific nutrients such as iodine, thiamine and pyridoxine; dietary levels of these nutrients affect the host-parasite relationships in filariasis and pyridoxine seems to be of particular importance in this respect. Filarial parasites obviously compete with their hosts for available nutrients and, in the real world, human filariasis is often associated with a deterioration in the plane of nutrition of infected individuals.

The host-parasite relationships in normal and protein-malnourished cotton rats infected with Litomosoides carinii (Nematoda: Filarioidea).

A total of 120 young cotton rats were fed ad libitum for 10 weeks on either synthetic diets containing 2.5, 5, 10 or 15% casein or on a stock breeding diet containing 20% crude protein. Half of the animals in each group were infected with the filarial nematode Litomosoides carinii and the food intake and body weight of each animal was measured. There was a trend towards increased food consumption in protein-deficient cotton rats and this was increased further in infected animals; however, differences between groups were not significant. Low protein diets reduced the rate of growth of uninfected and infected cotton rats; filarial infection intensified these adverse effects of under-nutrition and increased the number of rats which died in the lowest protein group. Protein deficiency had little effect on the number of L. carinii which developed, although fewer parasites became established in cotton rats fed on a 2.5% diet than in those fed on a 10% diet. Parasites developing in protein-deficient animals were shorter than those developing in well-fed ones and embryogenesis was retarded in female worms from protein-deficient animals. The onset of patency was retarded in protein-deficient animals and the microfilaraemia which developed subsequently was lower up to 120 days post-infection.

Vitamin A deficiency and the development of Litomosoides carinii (Nematoda, Filarioidea) in cotton rats.

This paper demonstrates that vitamin A deficient (A-) cotton rats are more susceptible to infection with Litomosoides carinii than normal (A+) cotton rats. However, embryogenesis is frequently retarded in female worms from A- hosts. Groups of young cotton rats were depleted of their liver stores of vitamin A by feeding them a vitamin A free diet from weaning. From 6 weeks of age this diet was supplemented with either 2, 5, 10, 25 or 100 IU vitamin A per 100 g body weight per day and half the animals in each group were infected with L. carinii. At autopsy, 51 days post-infection, serum vitamin A levels were proportional to vitamin A intake but were unaffected by infection (P less than 0.05). A+ cotton rats grew more rapidly and gained more weight than A- ones; infected animals gained less weight than their uninfected controls. More parasites developed in rats fed either 2 or 5 IU vitamin A than those fed either 10, 25 or 100 IU (P less than 0.02) and parasites from the 5 IU group were significantly longer than those from all other groups (P less than 0.02). However, microfilarial development was retarded in female worms from A- animals as compared with A+ ones.

In-vivo encapsulation and killing of Litomosoides carinii in white rats.

Ultrastructural studies revealed that in albino rats Litomosoides carinii was encapsulated and eventually killed in the pleural cavity by adherent host cells. Encapsulation was an organized cellular reaction which sequestered and eventually degraded the parasites. The process evolved in three phases: primary accumulation of host cells, especially eosinophils and macrophages, around the parasites with concentration of eosinophils on the parasite surface; secondary transformation of macrophages into epithelioid cells which replaced eosinophils on the parasite surface; finally, dead parasites became calcified and were gradually degraded within a tough, compacted fibrotic capsule.

Embryogenesis in Litomosoides carinii from pyridoxine deficient cotton rats.

Pyridoxine (vitamin B6) deficiency was induced in cotton rats which were then infected with the filarial parasite Litomosoides carinii. Embryogenesis was assessed microscopically in worms taken from pyridoxine deficient cotton rats and from various categories of control animals. Embryogenesis was retarded in worms from pyridoxine deficient hosts and more abnormal embryos were present in such worms than in those from control animals.