Effect of subordinance, lack of social hierarchy, and restricted feeding on murine survival and virus leukemia.

When caged in groups of three and fed ad libitum, dominant male mice survived longer than subordinate group members which again lived longer than males caged in groups of nine, among whom no rank order was established. In groups of nine the social structure was not affected when the food supply was reduced to the lowest level not affecting survival, but in groups of three, food reduction made the survival of both dominant and subordinate animals drop to a level matching that of groups of nine. After challenge with a small dose of Moloney virus, leukemia developed among ad libitum fed subordinate mice in groups of three and members of groups of nine, but not among the dominant animals. Food restriction enhanced the leukemia incidence, but dominant animals continued to go free. We conclude that subordinance and also lack of social hierarchy result in a higher incidence of virus induced leukemia, that severe food restriction does the same, and that the effect of social order on leukemia development prevails even under feeding conditions that nearly abolish group-related differences in survival.

The effects of a break in water fluoridation on the development of dental caries and fluorosis.

Durham, NC, fluoridated since 1962, had an 11-month cessation of fluoridation between September, 1990, and August, 1991. The purpose of this study was to assess the effects of this break on the development of caries and fluorosis in children. Study participants were continuously-resident children in Kindergarten through Grade 5 in Durham's elementary schools. There were 1696 children, 81.4% of those eligible, for whom a questionnaire was completed and clinical data recorded. Age cohorts were defined by a child's age at the time that fluoridation ceased. Caries was recorded in children in the Birth Cohort through Cohort 3, and fluorosis for children in Cohorts 1 through 5. Caries was assessed in the primary first and second molars according to the decayed-filled index; fluorosis on the labial surfaces of the upper permanent central and lateral incisors was assessed by the Thylstrup-Fejerskov (TF) index. Mother's education was associated with caries; higher education of the mother had an odds ratio of 0.53 (95% CI 0.40, 0.76) for caries in the child. No cohort effects could be discerned for caries. Overall prevalence of fluorosis was 44%. Prevalence in Cohorts 1, 2, 3, 4, and 5 was 39.8%, 32.3%, 33.0%, 62.3%, and 57.1%, respectively. These cohort differences remained statistically significant in regression analysis. It was concluded that while the break had little effect on caries, dental fluorosis is sensitive to even small changes in fluoride exposure from drinking water, and this sensitivity is greater at 1 to 3 years of age than at 4 or 5 years.

Sugared soda consumption and dental caries in the United States.

Because of the complexity of the caries process, the potential cariogenicity of specific food items is difficult to assess. The purpose of this study was to investigate the associations between sugared soda consumption and caries. Dietary and dental examination data from the 1988-94 Third National Health and Nutrition Examination Survey (NHANES III) were used. From the food frequency questionnaire and 24-hour recall data, significant associations between DMFS and soda consumption were generally seen in persons over age 25. No differences in DMFS, relative to soda consumption, were seen in persons under age 25, or in analyses of dfs for children under age 12. The observed associations could be due to the cumulative effects of the long-term consumption of sugared soda. The absence of apparent effects of sugared soda consumption in younger people may also be related to the increased use of fluorides since the 1960s.

Fluorosis development in seven age cohorts after an 11-month break in water fluoridation.

This study used an 11-month break in water fluoridation to identify the time when developing incisors are most sensitive to fluorosis development. The study was based in Durham, NC, where an interruption to water fluoridation occurred between September, 1990, and August, 1991. A total of 1896 children was dentally examined. Fluorosis was measured by the TF index, and parents or guardians completed a questionnaire on demographics and fluoride history. Age cohorts ranged from those born 5 years before the break, to those born 1 year after the resumption of fluoridation. Fluorosis prevalence for seven age cohorts whose birth years ranged from 1985-86 to 1991-92 was 57.1, 62.3, 33.0, 32.3, 39.8, 30.2, and 36.8%, respectively. Children aged from birth to 3 years at the break, and those born 1 year after it, had less fluorosis than those aged 4-5 years at the break.

Intermittent stress in pigs: effects on behavior, pituitary-adrenocortical axis, growth, and gastric ulceration.

Ninety-six pigs, half females and half castrated males from 12 litters, were housed in 24 groups of four litter mates. From an age of 115 days half of the groups were subjected to chronic stress for 33 days consisting of a schedule of unpredictable, inescapable electroshocks, and half served as controls. Behavior and performance were measured on all animals in the group, hormone data on one female in each group, and data on ulceration on the castrates. Behaviorally, the pigs did not habituate to 31 days of stress treatment. One to 2 days of stress treatment produced a behavioral activation that after 9 to 10 days was restricted to the time period of potential stress treatment. After 30 to 31 days it was replaced by passive behavior. In the beginning as well as after 30 to 31 days of intermittent stress, time spent sitting was increased. In addition, 6 days of intermittent stress reduced the baseline mean of plasma ACTH. After 33 days of stress the baseline mean of plasma ACTH was normalized, but the time course of diurnal secretion of ACTH was shifted. No effects of the chronic intermittent stress on basic levels of plasma cortisol, performance, or gastric ulceration were evident. In conclusion, the effect of intermittent stress depends on the number of days of intermittent stress treatment and it does not inevitably include changes in the basic levels of cortisol. Thus, assessment of stress must be based on a wide range of variables describing the process.

Nutrition knowledge, attitudes, and practices of older and younger elderly in rural areas.

Using a mailed survey, we gathered data to examine selected aspects of nutrition attitudes, knowledge, and practices of two groups of randomly selected older individuals living in rural areas. In one group respondents were 75 through 85 years old, and in the other group respondents were 60 through 70 years old. A senior nutrition survey and a shelf inventory were used to obtain information from the 698 respondents. The 60- through 70-year-old group expressed significantly more (P less than .001) positive attitudes for efficacy, intention, and outcome expectation than the older group. In addition, the younger group had a higher level (P less than .01) of knowledge about fat and salt. They also tended to make more healthful food selections in 7 of 11 categories of the shelf inventory. Our study suggests that 75- through 85-year-old individuals have different nutrition attitudes, knowledge, and practices. Nutrition education should focus on positive messages that are age appropriate, practical, and achievable. Specific topics should include information about beneficial outcomes of healthful eating behaviors.

Assessing beliefs of older rural Americans about nutrition education: use of the focus group approach.

We used the focus group interview technique as a preliminary research step in developing a nutrition education intervention for rural seniors who, because of less than optimal eating habits and changing demographics, are an important target audience. Sixty-eight well, active, rural North Dakota seniors, 60 years or older, from communities of 2,500 or fewer people, participated in five focus groups conducted in late summer 1988. As a qualitative research approach, focus group interviews offer a means of obtaining in-depth information on a specific topic from representatives of a target audience in a discussion group atmosphere. Focus groups require careful preparation and structuring and should include a capable moderator, a prepared discussion guide, carefully recruited participants, and a comfortable setting. The process generated ideas that we are using to develop a health promotion nutrition intervention that will be a mailed-home approach, including use of incentives, social role models, cholesterol screening, and learning activities. The intervention relies on the interest and ability of seniors to make positive health changes. We conclude that the focus group approach is useful in developing nutrition education interventions.

An attempt to separate the roles of corticosterone and ACTH in the control of post-shock fighting behaviour in male laboratory mice.

One experiment was conducted to separate the roles of corticosterone and ACTH in the mediation of the facilitatory effects of experiencing shock on subsequent fighting behaviour in male mice. It was found that (1) treatment with electric foot-shock and single injections of ACTH (one dose level) lead to comparable increases in subsequent fighting in intact males; (2) preventing changes in testosterone secretion by combined castration and testosterone replacement does not occlude or modify the facilitatory effects of shock or ACTH on subsequent fighting; and (3) preventing changes in both testosterone and corticosterone secretion by combined castration-adrenalectomy and testosterone-corticosterone replacement prevents shock and ACTH induced increases in fighting. These findings suggest that corticosterone plays a more important role than ACTH in the mediation of the facilitatory effects of shock on subsequent fighting behaviour in male mice.

Role of corticosterone in the control of post-shock fighting behaviour in male laboratory mice.

Two experiments were conducted to examine the role of corticosterone in controlling fighting subsequent to electric foot-shock in male mice. It was found that (1) treatment with corticosterone restores post-shock fighting in adrenalectomized males but not in castrated-adrenalectomized males; (2) raising cortieosterone levels induces post-shock fighting in castrated-adrenalectomized males treated with testosterone but not in castrated-adrenalectomized controls treated with a placebo; and (3) preventing corticosterone responses to shock occludes the increasing in fighting which normally follow shock in intact males. These findings suggest that (1) corticosterone plays an important role in the control of post-shock fighting in mice; (2) this importance of corticosterone is dependent on the presence of circulating testosterone, or other androgens; and (3) corticosterone responses to the experience of shock may be involved in the mediation of the facilitatory effects of this experience on subsequent fighting behaviour.

Effects of repeated exposure to electric footshock on subsequent agonistic behaviour and adrenocortical secretion in male mice of different androgen status.

Two experiments were conducted to examine effects of repeated exposure to electric footshock on subsequent agonistic behaviour and adrenocortical secretion in male mice of different androgen status. Aggressive and submissive behavioural components were independently studied in the two experiments. It was found that repetition reduced aggressive, and stimulated submissive and adrenocortical responses to shock, particularly in castrates. The direction of the shock effects on aggressive behaviour was reversed by repetition in castrates, whereas only the magnitude of the behavioural responses was changed at normal androgen levels. It is suggested that the changes in agonistic responses to shock induced by repetition are mediated by changes in pituitary-adrenocortical secretion, and that androgen inhibits the shock effects on agonistic behaviour through inhibition of the pituitary-adrenocortical responses to shock.

Role of the pituitary-adrenocortical axis in the control of agonistic behaviour after single and repeated footshock in castrated male mice.

Two experiments were conducted to examine the role of the pituitary-adrenocortical axis in the mediation of the effects of single and repeated electric footshock on subsequent agonistic responding in castrated male mice. It was found that (1) preventing corticosterone responses to shock occludes the facilitatory effects of single shock on both aggressive and submissive behaviour and occludes the additional increases in submissive behaviour which normally occur after repeated shock, and (2) blocking pituitary release of ACTH by dexamethasone treatment restores aggressive behaviour after repeated shock, independently of the initial levels of corticosterone and testosterone. These findings suggest that (1) increases in aggressive and submissive behaviour in response to single shock depend on shock-induced increases in corticosterone levels; (2) further increases in submissive behaviour in response to repeated shock require further increases in the corticosterone levels; and (3) inhibition of aggressive behaviour after shock repetition appears to depend on increases in ACTH levels, and occurs independently of the initial corticosterone and testosterone levels.

Temporal relationships between shock treatment and intermale fighting behaviour in laboratory mice. Effects of modifying testicular and adrenal functions.

The three experiments of this series were conducted to (1) examine subsequent effects of electric shock on intermale fighting in previously isolated mice, and (2) determine to what extent post-shock fighting is affected by manipulations of the pituitary-gonadal and pituitary-adrenocortical axes. In experiment 1 it was found that shock treatment significantly increases fighting 1 2 to 1 h later. Experiment 2 showed that castration alone does not affect post-shock fighting, whereas adrenalectomy and castration combined with adrenalectomy both inhibit such fighting. Experiment 3 showed that pretreatment with testosterone increases fighting in intact males, but fails to restore post-shock fighting in adrenalectomized and castrated-adrenalectomized males. These findings suggest that (1) the pituitary-adrenocortical axis plays an important role in controlling post-shock fighting in mice, and (2) the inhibition of post-shock fighting by adrenalectomy and castration combined with adrenalectomy is not a result of the loss of adrenal testosterone which accompanies these operations.

Effects of immobility stress and food restriction on stereotypies in low and high stereotyping female ranch mink.

Two experiments were conducted to examine the effects of repeated immobilisations and food restriction on normal activity and stereotypies in low and high stereotyping female ranch mink. Repeated immobilisations had immediate inhibitory effects on normal activity and stereotypies in both groups, whereas food restriction had the opposite immediate effects. Subsequent to both immobilisations and food restriction, stereotypies were increased, whereas normal activities returned to pre-experimental levels. Repeated immobilisations were followed by increases in cortisol levels in both low and high stereotyping females. High stereotyping females had lower baseline cortisol levels than low stereotypers but tended to show higher cortisol responses to immobilisations. These results indicate that stressful experiences may affect stereotypies, but that the direction of the changes depends on type of stressor as well as the duration of exposure to the stressor. It is moreover suggested that stereotypies can be emancipated.

Stress during mother-infant separation in ranch mink.

Effects of different mother-infant separation procedures on experienced stress by adults and young were studied using changes in circulating eosinophil levels as a stress indicator. It was found that (1) the amount of stress experienced by the mothers increases with the age of the pups at separation, when separation occurs as 6-week-, 8-week-, and 10-week-old pups, (2) eosinophil levels of mink pups show an ontogenetic development which complicates interpretations of the levels in terms of experienced stress, and (3) complete separation from 6-week-, 8-week-, or 10-week-old pups reduces experienced stress of the mothers more radically than simple physical separation involving removal of the pups to adjoining cages.

Fluid consumption related to climate among children in the United States.

OBJECTIVE: Recommended fluoride concentrations in US public water systems are between 0.7-1.2 ppm, depending on the mean daily maximum temperature. This range assumes that water intake is higher in warmer than in cooler climates, based on research from the 1950s. The aim of this analysis is to relate fluid consumption among American children aged 1-10 years to the local climate under modern conditions. METHODS: The quantities of daily total fluid intake per body weight (ml/kg) and plain water intake per body weight (ml/kg) of children were calculated from the 24-hour recall diet survey in the third National Health and Nutrition Examination Survey (NHANES III, 1988-94). The mean daily maximum temperature from 1961 to 1990, averaged for the month during which the NHANES III exam was conducted, was obtained for each survey location from the US Local Climate Historical Database. Multiple regression analysis was conducted using SAS and SUDAAN. RESULTS: Fluid intake was significantly associated with age, sex, socioeconomic status (SES), and race and ethnicity. No significant association could be found between the amount of either total fluid or plain water intake and mean daily maximum temperature, either before and after controlling for sex, age, SES, and race or ethnicity. CONCLUSIONS: Results indicate that there is no evidence that fluid consumption among children is significantly related to mean temperature in modern conditions. This suggests that the national temperature-related guidelines for fluoride concentration in drinking water may be due for reevaluation.

Water consumption in the United States in 1994-96 and implications for water fluoridation policy.

OBJECTIVES: The purpose of this project was to describe current water consumption patterns and to compare them to findings from earlier studies. Current water consumption data also were used to reevaluate the association between water consumption and climate. These findings are of importance in estimating fluoride intake from fluoridated water. METHODS: Findings from the 1994-96 Continuing Survey of Food Intakes by Individuals (CSFII) were compared to those from two earlier dietary studies, the 1977-78 Nationwide Food Consumption Survey (NFCS) and the pioneering research of Galagan and colleagues in the 1950s. Food consumption data were analyzed for 14,619 persons with food and beverage intake data for two 24-hour periods in the CSFII. RESULTS: Increased consumption of infant formulas and decreased consumption of tap water and cow's milk were seen in the CSFII for infants compared to the NFCS. Older children and adults showed increased consumption of carbonated beverages and juices. While Galagan and colleagues found about a 60 percent increase in water consumption between the coldest (55 degrees F) and warmest (85 degrees F) conditions, only a 20 percent difference was seen between the winter and summer months in certain regions in the CSFII. CONCLUSIONS: No obvious strong or consistent association between water intake and month or season was apparent in these recent data. These findings are preliminary, and suggest that water fluoridation policy requires further research regarding water consumption and climate.

Professionally applied topical fluoride and restorative care in insured children.

OBJECTIVES: This study evaluates the association between use of professionally applied topical fluoride and use of interproximal restorations in primary and permanent teeth of children. METHODS: Insurance claims from 15,190 children, for treatment provided by 1,556 different dentists, were analyzed to look for associations between frequency of use of professionally applied topical fluoride and use of interproximal restorations. The average follow-up period for the children included in the analysis was 5.3 years, with the range from 3.0 to 7.9 years. RESULTS: Both tabular and regression results failed to demonstrate an association between frequency of use of professionally applied topical fluoride and use of interproximal restorations in either the primary or permanent dentition. The most powerful predictor of restorative care for these children was the overall propensity of the dentist to place restorations in children. CONCLUSIONS: In this group of insured children, we were unable to find an association between the frequency of use of professionally applied topical fluoride and restorative care. Further, despite numerous recommendations that professionally applied topical fluorides should be used only in moderate- and high-caries children, approximately two-thirds of these children received topical fluoride at every recall visit, nearly two times per year.

Dental caries and dental fluorosis at varying water fluoride concentrations.

OBJECTIVES: The purpose of this study was to investigate the relationships between caries experience and dental fluorosis at different fluoride concentrations in drinking water. The impact of other fluoride products also was assessed. METHODS: This study used data from the 1986-87 National Survey of US School-children. Fluoride levels of school water were used as an indicator of the children's water fluoride exposure. The use of fluoride drops, tablets, professional fluoride treatments, and school fluoride rinses were ascertained from caregiver questionnaires. Only children with a single continuous residence (n = 18,755) were included in this analysis. RESULTS: The sharpest declines in dfs and DMFS were associated with increases in water fluoride levels between 0 and 0.7 ppm F, with little additional decline between 0.7 and 1.2 ppm F. Fluorosis prevalence was 13.5 percent, 21.7 percent, 29.9 percent, and 41.4 percent for children who consumed < 0.3, 0.3 to < 0.7, 0.7 to 1.2, and > 1.2 ppm F water. In addition to fluoridated water, the use of fluoride supplements was associated with both lower caries and increased fluorosis. CONCLUSIONS: A suitable trade-off between caries and fluorosis appears to occur around 0.7 ppm F. Data from this study suggest that a reconsideration of the policies concerning the most appropriate concentrations for water fluoridation might be appropriate for the United States.

Water consumption and nursing characteristics of infants by race and ethnicity.

OBJECTIVES: The purpose of this project was to determine racial/ethnic differences in water consumption levels and nursing habits of children younger than 2 years old. METHODS: Data from the 1994-96 Continuing Survey of Food intakes by individuals (CSFII) were used for these analyses. Water consumption and breast-feeding data on 946 children younger than 2 years old were used. RESULTS: For black non-Hispanic children younger than 2 years old (n = 121), 5.3 percent of the children were currently being breast fed. This percentage was less than that seen in other racial/ethnic groups. For white non-Hispanic children (n = 620), this percentage was 10.8 percent; for Hispanic children (n = 146), 12.2 percent; for "other" children, 18.5 percent (n = 59). Black non-Hispanic children had the highest total water consumption (128.6 ml/kg/day) among all groups, white non-Hispanic had the lowest (113.2 ml/kg/day). These differences were not statistically significant in multivariate regression modeling. Black non-Hispanic children also drank more tap water (21.3 ml/kg/day) than white non-Hispanic children (12.7 ml/kg/day) and Hispanic children (14.9 ml/kg/day). The difference was statistically significant in multivariate regression modeling. CONCLUSIONS: The differences in breast feeding and water consumption observed among black children younger than 2 years of age could be a factor in the observed higher levels of fluorosis in black children compared to other children.

Longitudinal evaluation of sealing molars with and without incipient dental caries in a public health program.

OBJECTIVES: This study undertook a retrospective evaluation of the effect of sealants on the caries experience of initially sound and incipient permanent first molar pit and fissure surfaces. METHODS: Records of children with complete five-year records were obtained from a school-based dental sealant program in a fluoridated community. Sealants were placed on 677 tooth surfaces in 96 children; 120 tooth surfaces in 17 children who received baseline examinations were not sealed because of lack of caregiver consent. Tooth surfaces were initially diagnosed as being sound or having incipient lesions, and evaluated for caries status after five years. RESULTS: For initially incipient surfaces the five-year decay rate was 10.8 percent (41 of 380 surfaces) for sealed surfaces and 51.8 percent (29 of 56 surfaces) for nonsealed surfaces with an odds ratio of 8.88 (95% CI = 4.56, 17.35). Initially sound surfaces had a decay rate of 8.1 percent (24 of 297 surfaces) for sealed surfaces and 12.5 percent (8 of 64 surfaces) for nonsealed surfaces with an odds ratio of 1.63 (95% CI = 0.63, 4.08). The two odds ratios were significantly different. CONCLUSIONS: Initially sound tooth surfaces were unlikely to become decayed in five years, and did not benefit greatly from the application of sealants. Within the limitations of this study, there were clear efficiencies in sealing incipient, but not sound, surfaces. The targeting of teeth with incipient caries for sealants is therefore recommended.