Recent years have witnessed the rise of the gut microbiota as a major topic of research interest in biology. Studies are revealing how variations and changes in the composition of the gut microbiota influence normal physiology and contribute to diseases ranging from inflammation to obesity. Accumulating data now indicate that the gut microbiota also communicates with the CNS — possibly through neural, endocrine and immune pathways — and thereby influences brain function and behaviour. Studies in germ-free animals and in animals exposed to pathogenic bacterial infections, probiotic bacteria or antibiotic drugs suggest a role for the gut microbiota in the regulation of anxiety, mood, cognition and pain. Thus, the emerging concept of a microbiota-gut-brain axis suggests that modulation of the gut microbiota may be a tractable strategy for developing novel therapeutics for complex CNS disorders.

/pdf/mind-altering-microorganisms-the-impact-of-the-gut-mf1hkt82wc.pdf

Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour

The impact of the gut microbiota on human health: an integrative view.

Alterations in intestinal microbiota composition are associated with several chronic conditions, including obesity and inflammatory diseases. The microbiota of older people displays greater inter-individual variation than that of younger adults. Here we show that the faecal microbiota composition from 178 elderly subjects formed groups, correlating with residence location in the community, day-hospital, rehabilitation or in long-term residential care. However, clustering of subjects by diet separated them by the same residence location and microbiota groupings. The separation of microbiota composition significantly correlated with measures of frailty, co-morbidity, nutritional status, markers of inflammation and with metabolites in faecal water. The individual microbiota of people in long-stay care was significantly less diverse than that of community dwellers. Loss of community-associated microbiota correlated with increased frailty. Collectively, the data support a relationship between diet, microbiota and health status, and indicate a role for diet-driven microbiota alterations in varying rates of health decline upon ageing.

/pdf/gut-microbiota-composition-correlates-with-diet-and-health-2dnsw10044.pdf

Gut microbiota composition correlates with diet and health in the elderly

Gene families are growing rapidly, but standard methods for inferring phylogenies do not scale to alignments with over 10,000 sequences. We present FastTree, a method for constructing large phylogenies and for estimating their reliability. Instead of storing a distance matrix, FastTree stores sequence profiles of internal nodes in the tree. FastTree uses these profiles to implement neighbor-joining and uses heuristics to quickly identify candidate joins. FastTree then uses nearest-neighbor interchanges to reduce the length of the tree. For an alignment with N sequences, L sites, and a different characters, a distance matrix requires O(N^2) space and O(N^2 L) time, but FastTree requires just O( NLa + N sqrt(N) ) memory and O( N sqrt(N) log(N) L a ) time. To estimate the tree's reliability, FastTree uses local bootstrapping, which gives another 100-fold speedup over a distance matrix. For example, FastTree computed a tree and support values for 158,022 distinct 16S ribosomal RNAs in 17 hours and 2.4 gigabytes of memory. Just computing pairwise Jukes-Cantor distances and storing them, without inferring a tree or bootstrapping, would require 17 hours and 50 gigabytes of memory. In simulations, FastTree was slightly more accurate than neighbor joining, BIONJ, or FastME; on genuine alignments, FastTree's topologies had higher likelihoods. FastTree is available at http://microbesonline.org/fasttree.

/pdf/fast-tree-computing-large-minimum-evolution-trees-with-4grq0gwfpy.pdf

Fast Tree: Computing Large Minimum-Evolution Trees with Profiles instead of a Distance Matrix

Human Genetics Shape the Gut Microbiome

Alterations in the human intestinal microbiota are linked to conditions including inflammatory bowel disease, irritable bowel syndrome, and obesity. The microbiota also undergoes substantial changes at the extremes of life, in infants and older people, the ramifications of which are still being explored. We applied pyrosequencing of over 40,000 16S rRNA gene V4 region amplicons per subject to characterize the fecal microbiota in 161 subjects aged 65 y and older and 9 younger control subjects. The microbiota of each individual subject constituted a unique profile that was separable from all others. In 68% of the individuals, the microbiota was dominated by phylum Bacteroides, with an average proportion of 57% across all 161 baseline samples. Phylum Firmicutes had an average proportion of 40%. The proportions of some phyla and genera associated with disease or health also varied dramatically, including Proteobacteria, Actinobacteria, and Faecalibacteria. The core microbiota of elderly subjects was distinct from that previously established for younger adults, with a greater proportion of Bacteroides spp. and distinct abundance patterns of Clostridium groups. Analyses of 26 fecal microbiota datasets from 3-month follow-up samples indicated that in 85% of the subjects, the microbiota composition was more like the corresponding time-0 sample than any other dataset. We conclude that the fecal microbiota of the elderly shows temporal stability over limited time in the majority of subjects but is characterized by unusual phylum proportions and extreme variability.

https://www.pnas.org/content/pnas/108/Supplement_1/4586.full.pdf

Composition, variability, and temporal stability of the intestinal microbiota of the elderly

Executive Summary highlights: Since 1964, water supplies in the Republic of Ireland (RoI) have been adjusted to 0.8 to
1.0 parts per million (ppm) fluoride. Currently 71% of the population receive fluoridated
domestic water supplies.
• In RoI, decay levels are lower among children with fluoridated domestic water supplies than
they are among those with no domestic water fluoridation.
• Decay levels are lower among children who get fluoride in their water supply in RoI than they
are among children in Northern Ireland (NI, no water fluoridation).
• Although decay levels are higher amongst the less well off, disadvantage does not account for
the difference seen between flouridated and non flouridated areas. Fluoridation is effective
in both disadvantaged and non disadvantaged groups.
• The prevalence of dental fluorosis (most commonly seen as paper white patches or fine white
lines on the tooth enamel) is higher amongst children and adolescents with fluoridated water
supplies.
• Despite the effectiveness of water fluoridation and fluoride toothpastes, there is little cause
for complacency since tooth decay continues to be a very common disease. For example by
age 15, 73% of adolescents with fluoridated water supplies in RoI already have decay in their
permanent teeth, this compares with 81% in non fluoridated NI.
• Children in RoI have amongst the highest frequency of consumption of foods and drinks
sweetened with sugar when compared with 34 other countries (WHO). Given their
unfavourable dietary habits and average or below average frequency of brushing (WHO),
water fluoridation continues to be an important preventive agent for the control of dental
decay levels in Ireland.
• The factors associated with variation in decay levels amongst 15-year-old adolescents in RoI
were fluoridation status, parents’ occupational status, frequency of tooth brushing, method
of rinsing after tooth brushing and frequency of snacking.
• In NI, there were two factors found to be associated with varying decay levels amongst 15-
year-old adolescents, these were parents’ occupational status and amount of toothpaste used
when brushing.
• The level of oral hygiene was judged to be unsatisfactory for the majority of children in RoI;
this variable was not measured in NI.
• The percentage of 15-year-olds who were under orthodontic treatment or had completed
treatment rose from 14% in 1984 to 23% in 2002 in RoI.
• Dependants of medical card holders were less likely to have had orthodontic treatment than
those without medical cards (17% vs 26%).
• Amongst 15-year-olds, 22% of those in RoI had trauma to their anterior teeth, compared with
14% in NI. A high proportion of this trauma to anterior teeth remains untreated in RoI.
• In RoI, one in five 12-year-old children, and one in three 15-year-old adolescents, had tooth
wear exposing dentine on at least one anterior permanent tooth.
• In RoI, 46% of parents were ‘very satisfied’ and 37% were ‘satisfied’ with the dental service
provided to their children, 4% of parents were either ‘dissatisfied’ or ‘very dissatisfied’ with
the service. In NI, almost all the parents completing the questionnaire were either ‘very
satisfied’ (69%) or ‘satisfied’ (29%) with the service provided.

North South survey of children’s oral health in Ireland 2002

Browne D, Whelton H, O’Mullane D, Tavener J, Flannery E. The aesthetic impact of enamel fluorosis on Irish adolescents. Community Dent Oral Epidemiol 2011; 39: 127–136. © 2011 John Wiley & Sons A/S



Abstract –  Objectives:  To assess the impact of differing degrees of enamel fluorosis on dental aesthetics according to Irish adolescents. The same participants also aesthetically rated other variations in dental appearances including a carious lesion, bleached teeth and a demarcated opacity.



Methods:  One hundred and fifty adolescents examined seven identical template photographs of an attractive dental smile displaying varying levels of enamel fluorosis (TF1, TF2, TF3), a demarcated opacity, no fluorosis (TF0), anterior caries and very white or bleached teeth. By indicating their level of agreement or disagreement with five statements on a five-point Likert scale, the participants rated the aesthetic acceptability of each of the photographs.



Results:  Using paired t-tests with the Bonferroni correction, it was found that the photographs depicting the very white teeth and anterior caries were rated as the most and least aesthetically pleasing images, respectively. There was no significant difference in the ratings of the photographs displaying TF0, TF1 and TF2 levels of fluorosis indicating that these photographs were viewed similarly (P > 0.002). The remaining two photographs (TF3 and the demarcated opacity) were rated similarly and significantly worse (P < 0.002) than the photographs showing no or low grades of fluorosis (TF0, TF1 and TF2).



Conclusions:  TF3 level of fluorosis represented the break point at which enamel fluorosis became aesthetically objectionable to these participants. Low grades of fluorosis (TF1 and TF2) were rated similarly to the photograph depicting no fluorosis (TF0).

The aesthetic impact of enamel fluorosis on Irish adolescents

A survey of the oral health and need for dental treatment was undertaken on children and adolescents with special needs in Ireland in 2003. The group had predominantly mild and moderate disabilities although a small number had severe impairments. The participants’ potential for cooperation with dental care ranged from those who could receive routine dental treatment in a primary care setting to those who would require sedation or general anaesthesia for even the most basic dental examination. The Disability Act 2005 outlines our responsibilities to people with disabilities. Good oral health is a right and indeed is integral to enabling the better assimilation of people with disabilities into society. Poor oral health, ugly stained teeth, abscesses, gaps and bad breath detracts from people’s quality of life and compounds the disadvantage that many of these children and adolescents already suffer. Prevention of oral disease in this sub group of the population is therefore fundamental since the need for dental treatment, or its provision, may further add to the morbidity and even mortality for some patients. The consequences of tooth loss can be particularly devastating for those with disabilities and permanent tooth loss levels among this young population already exceed that amongst the same age group in the general population The findings are summarised at the start of this report followed by the full results and more detailed summaries for each section. The major considerations for policy makers revealed by the study results are that: The current level of oral and dental care available to children and adolescents with special needs is inadequate and urgently needs to be expanded in order to bring services up to an acceptable level, comparable at least to that of their peers or better, given the serious health consequences of oral diseases for this group of children and adolescents. The results not only expose the lack of suitably trained personnel to deliver a quality service but also the precarious reliance on a small cohort of very dedicated and experienced dental teams, inequitably distributed across the country. The results of this survey point to the fact that for many, their first encounter with the dental services is too late since oral and dental diseases have become established and accessing and accepting dental care will pose significant new challenges.. Thirty-five percent of children in the five-year-old group had never been to a dentist. Fourteen percent of children from the 12-year-old group and 21% from the 15-year-old group had their first ever visit to a dentist when they were 9 years of age or older. One in three of the 12- and 15-year-old group with special needs had already received dental treatment under a general anaesthetic. The consequences of this approach are seen in the results of the oral health survey of adults with intellectual impairments1 Early introduction to the dental service and tailored oral hygiene support is fundamental for children and adolescents with special needs. Oral and dental diseases are avoidable and prevention is paramount given the high probability of requiring general anaesthesia (with its accompanying risks and cost) for the provision of what for children without disability would be routine care.

Oral health of children attending special needs schools and day care centres

BACKGROUND AND DESIGN parental accompaniment of children during dental treatment has always been a contentious issue. One of the factors that should be considered is the preference of the parents. The aim of this paper is to report the preference of parents of eight-year-old schoolchildren in Ireland in relation to accompanying their child during dental procedures and is part of the National Survey of Children's Dental Health in Ireland, which was conducted between October 2001 and June 2002. The survey had a cross sectional design and parents of children (average age 8.4 years) selected for dental examination were asked to complete a questionnaire. RESULTS 3629 completed questionnaires were obtained from parents of eight-year-old children giving a response rate of 68 per cent. Sixty-seven per cent of parents expressed a preference to accompany their child during dental treatment, while nine per cent expressed a preference not to accompany their child. The sex of the child (p = 0.33) or the fact that the parents were holders of a medical card (surrogate for disadvantage) (p = 0.08) did not affect parents' preference. However, parents of a single child had a higher preference (78 per cent) for accompanying their child than did parents with greater than one child in the family unit (66 per cent) (p = 0.0009). CONCLUSION If given the choice, the majority of parents would prefer to accompany their child when receiving dental treatment.

E. Flannery

Papers

Composition, variability, and temporal stability of the intestinal microbiota of the elderly

North South survey of children’s oral health in Ireland 2002

The aesthetic impact of enamel fluorosis on Irish adolescents

Oral health of children attending special needs schools and day care centres

Parents' preference as to whether they would like to accompany their child when receiving dental treatment - results from a national survey.