The p75 neurotrophin receptor augments survival signaling in the striatum of pre-symptomatic Q175(WT/HD) mice.

Huntington's disease (HD) is a dominantly inherited neurodegenerative disorder characterized by a constellation of motor, cognitive, and psychiatric features. Striatal medium spiny neurons, one of the most affected populations, are dependent on brain-derived neurotrophic factor (BDNF) anterogradely transported from the cortex for proper function and survival. Recent studies suggest both receptors for BDNF, TrkB and p75 neurotrophin receptor (p75), are improperly regulated in the striata of HD patients and mouse models of HD. While BDNF-TrkB signaling almost exclusively promotes survival and metabolic function, p75 signaling is able to induce survival or apoptosis depending on the available ligand and associated co-receptor. We investigated the role of p75 in the Q175 knock-in mouse model of HD by examining the levels and activation of downstream signaling molecules, and subsequently examining Hdh(+/Q175);p75(-/-) mice to determine if p75 represents a promising therapeutic target. In Hdh(+/Q175);p75(+/+) mice, we observed enhanced survival signaling as evidenced by an increase in phosphorylation and activation of Akt and the p65 subunit of NFκB in the striatum at 5 months of age and an increase in XIAP expression compared to Hdh(+/+);p75(+/+) mice; this increase was lost in Hdh(+/Q175);p75(-/-) mice. Hdh(+/Q175);p75(-/-) mice also showed a decrease in Bcl-XL expression by immunoblotting compared to Hdh(+/Q175);p75(+/+) and Hdh(+/+);p75(+/+) littermates. Consistent with diminished survival signaling, DARPP-32 expression decreased both by immunoblotting and by immunohistochemistry in Hdh(+/Q175);p75(-/-) mice compared to Hdh(+/+);p75(+/+), Hdh(+/Q175);p75(+/+), and Hdh(+/+);p75(-/-) littermates. Additionally, striatal volume declined to a greater extent in Hdh(+/Q175);p75(-/-) when compared to Hdh(+/Q175);p75(+/+) littermates at 12 months, indicating a more aggressive onset of degeneration. These data suggest that p75 signaling plays an early role in augmenting pro-survival signaling in the striatum and that disruption of p75 signaling at a pre-symptomatic age may exacerbate pathologic changes in Hdh(+/Q175) mice.

Participation, willingness and abilities of school-teachers in oral health education in Tanzania.

In Tanzania, teachers in primary schools conduct oral health education as part of the school syllabus, most of them without any training for the task. The participation, willingness and abilities of teachers involved in this duty were studied by means of questionnaire, interviews, oral hygiene examinations and practical exercises. The teachers' knowledge of oral health matters and their skills in toothbrushing were poor. Health lessons in general were not accorded high priority. The teachers preferred parents to instruct their children on toothbrushing, and were reluctant to teach pupils about dietary matters. They stressed the shortage of time and materials for teaching health lessons and their heavy workload at school. These findings indicate a necessity, and a point of departure, for organising training for oral health education and encouraging teachers to undertake this task.

Oral health knowledge, attitudes, behaviour and skills of children entering school in urban and rural areas in Tanzania.

This study analysed the prevailing oral health-related knowledge, attitudes and behaviour of children entering school in Tanzania. The assessment was conducted in a random sample of 200 children who were newly enrolled in first grade in urban and rural areas of the Ilala district, by means of interviews, oral hygiene check-ups and practical exercises. Toothbrushing was a prevalent habit among these children, but its efficiency was low. Modern toothbrushes were commonly used and preferred to wooden toothbrushes. Toothpaste was considered essential and commonly used in urban areas but, instead, charcoal or ash were used in rural areas. The children's sugar consumption was low, but they widely valued sugary snacks. They had low awareness of gum disease and tooth decay, and poor knowledge about the causes and prevention of these diseases. These findings indicate gaps in the children's oral health ideas and practices acquired from home. The ongoing school oral health education is a crucial opportunity for the required improvements.

Three methods of oral health education in secondary schools.

In 1990, three methods of oral health education (OHE) were implemented in three secondary schools in the city of Pori, Finland, one method in each school. The traditional OHE consisted of a lecture given by a dentist with the aid of transparencies and slides. The peer OHE consisted of a lecture given by six pupils from the upper grades. These pupils used transparencies and extracts of video films and had a classroom exhibition with pictures, slogans, and dental aids and instruments. The self-teaching OHE was based on an exhibition from which the pupils searched for the information themselves. After the programs, the pupils' opinions about the method itself, its contents and implementation, knowledge about certain oral health issues, and the possible effect of the method were determined by a questionnaire. The attitudes and opinions were most positive in the peer OHE group. The traditional OHE was quite well accepted, but the self-teaching method was not very successful. The participants in the traditional OHE more often felt that they had been encouraged to pursue good oral health habits. In all groups, the topic considered to be the most boring was tooth brushing. Peer OHE can be recommended for Finnish secondary schools. The issue of tooth brushing should be played down, however, as too frequent repetition of the topic may cause more negative attitudes towards oral health education and practices.

Coverage of public oral health services for young children in Finland.

In the Finnish programme of public oral health care for preschool children, every child is eligible for free care. The coverage of the programme has been high, about 85%. The aim of this study was to determine, whether the nonparticipants of the programme actually do have equality in making the choice to participate. The barriers to care were identified. All 4- to 6-year-old children who were registered administratively as nonparticipants in oral health care in 1981 and their randomly selected controls were studied in the city of Lahti. Detailed analysis of nonparticipation showed that some children had been misclassified as nonparticipants in the administrative statistics, indicating the national coverage of the programme to be higher than reported. Based on this finding, suggestions are made for increasing reliability of official statistics. Multiple logistic regression analysis for 36 factors resulted in three main barriers to utilization. Children of single-parent families in which the parent had a low level of education and difficulties to take time off work had the highest risk of nonutilization and thus had little choice to participate. Children with fear to dental care, regardless of any characteristic of the family or parents, were at increased risk of nonparticipation. Not having received the invitation to an examination also increased nonutilization, regardless of any factors related to family, parents or child. It was concluded, however, that these barriers to utilization could be manipulated by the system of public oral health care.

Use of children's oral health services in Finland with special reference to heavy consumption.

The consumption of oral health services among 4-16-yr-old children in Finland is described, including an analysis of heavy consumption. Data representative of all Finnish children were collected for 4518 children from municipal health centers and homes. The response rate was 85%. Children with orthodontic visits during the year were excluded from the analyses. Of the preschoolchildren 12% and of the school-age children 4% did not use any oral health services during the studied year. Non-users did not differ from the others in terms of socioeconomic status, distance to a health center or type of residential area. Public oral health services were used very unevenly. Half of the children consumed only one-fifth of the services and the next one-third used about one-third of the services. The heavy consumers, about one-fifth of the total, used as much as half of all the services. Among preschoolchildren, the heavy consumers were mainly from lower socioeconomic groups. In contrast, no clear predictive factors were found for heavy consumption among the schoolchildren. Heavy consumers had more both treated and untreated caries than the other children did. Their treatment was mainly restorative; at least half of them did not receive adequate preventive care. Finnish public oral health care clearly should make more efforts to ensure that heavy consumers of dental services do not remain so.

Oral health education in Finnish schools.

The public system of oral health care in Finland, as in the other Nordic countries, is responsible for arranging oral health education for school classes. In this study the coverage and the personnel implementing these lessons in Finnish schools were assessed. A questionnaire was sent to all health centers (n = 214). The response rate was 87%. A total of over 23,000 oral health lessons were arranged in schools during the year studied. Coverage was high in primary schools, lower in secondary schools and lower still in high schools. The main implementers of the lessons were dental assistants. The conclusions of the study were: 1) coverage of teenagers should be increased, 2) the role of dental hygienists and dentists in implementing the program should be greater, and 3) oral health personnel and teachers should cooperate more actively.

Role of social class in caries occurrence in primary teeth.

The independent effect of social class on (A) the risk of having any caries (deft greater than or equal to 1) and on (B) the risk of having a few caries defects (deft greater than or equal to 3) in primary teeth was studied. The data, which were representative for all Finnish children of this age group, were collected by questionnaires from health centres and homes for 1637 children aged 2.5 to 7.5 years. The response rate was 83%. According to logistic regression analyses, children in the upper social class were clearly at lower risk of having caries than were children in the middle social class, independent of the child's age or sex, reported frequency of toothbrushing, consumption of sugar or use of fluoride tablets. In contrast, children in the lower social class had a higher risk of caries, which was independent of the reported dental health behaviour of the children. The results indicate that the differences among social classes in caries occurrence could not be eliminated by changes in dental health habits. Basic and applied research is needed to identify the relevant factors in socioeconomic status related to caries occurrence so that the differences in dental health between preschool children in different social classes can be reduced.

Caries frequency among 6-17-year-old participants of the Finnish public dental care during 1975-79.

Temporal trends of caries frequency in 6-17-year-old children in Finland and its counties during 1975-79 are reported. Initially the attendance rate was 70%: during the 4-year follow-up it increased to 84%. The cross-sectional annual proportion of children needing curative treatment diminished from 80% to 67% at the age of 8 years; the changes among the 12- and 16-year-old children were 78-66% and 86-76%, respectively. The proportion of entirely caries-free children increased from 2.5% to 9.2% at the age of 8 years, only a slight increase was found in the older age groups. The mean DMFT value decreased continuously at all ages: in the 8-year-old children it decreased from 2.7% to 1.7%, in 12-year-olds from 6.7% to 5.2% and at the age of 16 from 13.4% to 11.6%. The caries scores decreased most in areas where the initial values were highest. In the county with high fluoride levels, where the initial caries scores were smallest, only slight improvement in the caries situation was found; this indicates no major change in recording of caries. Although a simultaneous improvement of the national attendance rate and the caries scores were observed, no consistent associations were found between the changes in the attendance rate and the changes in various caries indices when age and geographical area were considered in the analyses. It is concluded that the marked decrease in caries frequency is mainly due to preventive measures.

Caries in primary dentition and social class in high and low fluoride areas.

Of the two random samples studied, the first represented 6--8 year-old residents of a natural high fluoride area (n = 115) and resident of all other areas of Finland (n = 1219). The second sample was representative for 7--9-year-old children participating in public dental care in one Finnish country. Structured questionnaires were used to collect data on social class; caries diagnoses were made by local dentists in municipal dental clinics. Children in the highest social class had the lowest caries experience in both high and low fluoride areas. Differences between middle and lower social class children were small. Fluoride affected caries in the primary dentition similarly in all social classes; in both samples this was shown statistically by nonsignificant interaction between social class and fluoride. In Finland, differences between social classes in caries in the primary dentition cannot be removed solely by implementing water fluoridation.

Caries of primary teeth and regularity of dental check-ups.

The study consisted of 1332 children representing 81% of a stratified random sample from the Finnish population born in 1970-72. Data on annual dental check-ups at the age of 2-5 years, caries at the age of 6-8 years, and social class were obtained by questionnaire from municipal dental clinics. Sixteen percent of the children had had regular (3-4) check-ups, 42% occasional (1-2) check-ups and 42% no dental check-ups. Proportion of children with no check-ups was somewhat higher in the highest than in the other social classes. Of the children having no reported check-ups, 27% were entirely caries free; 20% of those having occasional and 20% of hose having regular check-ups were caries free. The mean dmft values among patients with one or more dmf teeth was 5.5 in children with no reported check-ups, 6.0 and 5.8 in those with occasional or regular check-ups. The mean dt values were 2.9, 2.26 and 2.3, respectively. In cases with no history of check-ups, the mean ft value among patients with one or more dmf teeth was 2.8, with occasional check-ups, 3.6, and with regular check-ups, 3.9. Thus a negative correlation existed between number of annual dental check-ups and number of untreated caries lesions found in cross-sectional examination; a positive correlation existed between frequency of check-ups and fillings found cross-sectionally. No clear correlation existed between regularity of annual dental check-ups and past caries experience (dmft).