Evidence of Early Emergence of the Primary Dentition in a Northern Plains American Indian Population.

The purposes of this study were to describe primary tooth emergence in an American Indian (AI) population during the first 36 mo of life to compare 1) patterns of emergence between male and female children and 2) tooth emergence between these AI children and other U.S. ethnic groups. Data were derived from a birth cohort of 239 AI children from a Northern Plains tribe participating in a longitudinal study of early childhood caries, with examination data at target ages of 8, 12, 16, 22, 28, and 36 mo of age (±1 mo). Patterns of emergence in AI children were characterized and sex comparisons accomplished with interval-censored survival methodology. Numbers of erupted teeth in AI children at each age were compared via Kruskal-Wallis tests against those in children of the same age, as drawn from a cross-sectional study of dental caries patterns in Arizona; these comparisons were based on the dental examinations of 547 White non-Hispanic and 677 Hispanic children. Characterization of time to achievement of various milestones-including emergence of the anterior teeth, the first molars, and the complete primary dentition-provided no evidence of sex differences among AI children. AI children had significantly more teeth present at 8 mo (median, 3) than either White non-Hispanic (P < 0.0063) or Hispanic (P < 0.0001) children (median, 2 each). This was also true at 12 mo (P < 0.001; medians, 8 vs. 6 and 7, respectively) and 16 mo (P < 0.001; medians, 12 vs. 11 each). Less pronounced differences were seen at 22 mo (P < 0.0001). White non-Hispanic and Hispanic children did not differ at any time considered (P > 0.05). These results provide evidence of earlier tooth emergence in AI children than in the other 2 ethnicities. Although the underlying etiology of the severity of early childhood caries in AI children is likely to be multifactorial, earlier tooth emergence may be a contributing factor. Knowledge Transfer Statement: The findings of this study have practical implications for practitioners providing childhood oral health care to ethnic groups with early tooth emergence. It may be important to provide parents with information on toothbrushing, dentist visits, and other practices supportive of good oral health as early as possible to protect their children's primary dentition.

Distribution of Leaf-Feeding Beetles and Bean pod mottle virus (BPMV) in Illinois and Transmission of BPMV in Soybean.

Bean leaf beetles (BLB; Cerotoma trifurcata) were collected in soybean (Glycine max) fields in 58 and 99 Illinois counties surveyed during the 2000 and 2001 growing seasons, respectively. In 2000, BLB counts were highest in the central portion of the state. BLB counts were lower the following year, but were more uniformly distributed throughout the state. BLB tested positive for Bean pod mottle virus (BPMV) in 37 of 41 counties assayed in 2000. In 2001, BLB tested positive for BPMV in 86 of 99 counties sampled. In 2000 and 2001, western corn rootworm (WCR; Diabrotica virgifera virgifera) adults were abundant in soybean fields only in east central Illinois. WCR adults tested positive for BPMV in 21 of 21 east central Illinois counties in 2000 and 20 of 24 sampled in 2001. BPMV was detected in soybean plants in 38 of 46 counties sampled in 2000. Field-collected WCR adults transmitted BPMV to potted soybean plants at low rates either directly from BPMV-infected soybean fields or with prior feeding on BPMV-infected plants. This is the first report of the distribution of BLB, WCR adults, and BPMV in Illinois and of BPMV transmission by adult WCR.

Age and stress history effects on spatial performance in a swim task in Fischer-344 rats.

This study determined whether prior habituation to water immersion would ameliorate age-related deficits in learning and memory in a swim task. Aged (22 months) and young adult (3 months) rats were immersed in water (30 degrees C) for 15 min on each of 28 consecutive days before training in the swim task. Additional groups of age-matched animals served as handled controls. Training on a spatial discrimination version of the water task was conducted over 5 days with two trials per day (1-h intertrial interval). A probe trial was substituted for the last trial on the fifth day to assess the rats' use of spatial information. Three days later, rats received cue discrimination training to find a visible platform. In the spatial task, prior habituation to water immersion ameliorated deficits in acquisition within each day (i.e., at a 1-h intertrial interval) but not across days (at 24 h). The results obtained with the 24-h interval confirm the rapid forgetting characteristic of aged rats in many tasks. The stress-habituation procedures reduced age-related deficits seen on the probe trial and on cue discrimination training. These findings indicate that several aspects of age-related impairments in the swim task, often attributed to primary age-related deficits in learning and memory processes per se, may instead be secondary to age-related differences in stress responses to water immersion.

Age-related changes in plasma catecholamine and glucose responses of F-344 rats to a single footshock as used in inhibitory avoidance training.

Young adult (3 months) and aged (22 months) Fischer 344 male rats were prepared with chronic tail artery catheters. Two days after surgery, rats were transferred to a test chamber and exposed to a single footshock (0, 0.25, 0.50, or 1.0 mA for 1 s). Blood samples were obtained from each rat under basal conditions and at timed intervals after exposure to footshock. Basal plasma levels of norepinephrine (NE) and epinephrine (EPI) were similar for 3- and 22-month-old rats. In contrast, plasma glucose (GLU) levels were significantly lower in aged rats compared to young adults. Increments in plasma levels of EPI were greater in aged rats compared to young adult controls following transfer of rats to the test chamber. In addition, aged rats had potentiated plasma EPI responses to footshock. Finally, aged rats had greater plasma levels of both catecholamines up to 5 min after a single training footshock compared to young adult controls. However, the increased responsiveness of EPI in aged rats was not accompanied by proportionate increases in plasma GLU levels, i.e., the EPI-GLU relationship was uncoupled in aged rats. These findings point to dramatic differences between young adult and aged rats in their plasma EPI responses to inhibitory avoidance training. Age-related increases in EPI secreted from the adrenal medulla, together with decreased blood GLU responses, may contribute in part to age-related deficits in memory modulatory processes.

Age-related changes in plasma catecholamine responses to chronic intermittent stress.

We examined habituation and sensitization of plasma catecholamine responses to stressful stimulation in young adult (3 months) and aged (22 months) Fischer 344 (F-344) male rats. Aged rats had greater elevations in plasma levels of norepinephrine (NE) and epinephrine (EPI) following exposure to restraint stress compared to young adult controls. Within ages, plasma catecholamine responses were similar in rats stressed for the first time compared to those stressed for the 27th time. When chronically stressed young adult and aged F-344 rats were exposed to a novel stressor, swim stress at 25 degrees C, plasma catecholamine responses were significantly greater than for age-matched handled controls. The magnitude of sensitization of plasma catecholamine responses to the novel stressor was similar for young adult and aged F-344 rats. These results indicate that aged rats have enhanced plasma catecholamine responses to acute restraint stress compared to young adults. In addition, rats of both ages displayed comparable levels of sensitization of plasma catecholamine responses to a novel stressor. These findings emphasize that aged rats differ from young adult rats in some but not all aspects of sympathetic-adrenal medullary regulation. Further, these age-related differences in sympathetic-adrenal medullary responses are unmasked when animals are exposed to stressful stimulation.

Age-related changes in plasma catecholamine responses to acute swim stress.

Young adult (3 months) and aged (22 months) Fischer 344 male rats were prepared with chronic tail artery catheters. Three days after surgery, rats were exposed acutely to swim stress at 20, 25, 30, or 35 degrees C for 15 min. Blood samples were obtained from each rat under basal conditions, at the end of the swim stress episode, and 15, 30, and 45 min after swim stress. Basal plasma levels of norepinephrine and epinephrine (EPI) were similar for 3- and 22-month-old rats. In contrast, plasma catecholamine responses of aged rats were significantly greater than those of young adult rats following swim stress at 20 and 25 degrees C. Plasma catecholamine responses were similar for rats of the two ages following swim stress at 30 or 35 degrees C. These findings indicate that aged rats have exaggerated sympathetic-adrenal medullary responses to acute swim stress at the lower water temperatures. Given the modulatory effects of plasma EPI on memory, these age-related alterations in plasma catecholamine responses to acute swim stress may influence spatial memory performance of rats in the Morris water maze.

Psychosocial correlates of immune responsiveness and illness episodes in US Air Force Academy cadets undergoing basic cadet training.

This study examined psychosocial correlates of immune function and illness in 89 male first-year US Air Force Academy cadets. A psychosocial questionnaire was administered to cadets prior to their arrival at the academy and was readministered during cadet orientation and during the stressful environment of Basic Cadet Training (BCT). Immune responsiveness was analyzed by PHA-, PMA-, or anti-CD3-stimulated thymidine uptake in mononuclear leucocytes. Illness episodes were assessed via medical chart review and self-reported symptoms. There were significant increases in distress levels as cadets entered BCT. No psychosocial measure assessed prior to arrival at the academy predicted level of PHA-, PMA-, and anti-CD3-stimulated thymidine uptake or risk of illness. However, hostility levels reported during BCT predicted risk of illness in the four weeks following psychosocial assessment (odds ratio = 7.1; 95% confidence interval: 1.4-36.1). Elevated response to environmental stressors and lower well-being levels also predicted impending illness, but only in the cohort of cadets who had not contracted food poisoning prior to assessment during BCT (OR = 9.3, CI = 1.9-46.7; OR = 0.09, CI = 0.02-0.53). These results suggest that self-report measures of hostility, response to environmental stressors and well-being may be useful predictors of impending illness episodes in males encountering high stress environments.

Immune responsiveness and risk of illness in U.S. Air Force Academy cadets during basic cadet training.

It has been proposed, but not confirmed, that environmental stressors alter immune function and increase the risk of viral infection among healthy individuals. We evaluated this hypothesis, examining the relationship among stress, immune function, and illness in 96 first-year U.S. Air Force Academy cadets during orientation and 4 weeks later during the stressful environment of Basic Cadet Training (BCT). Perceived stress and well-being levels of cadets were assessed via questionnaire. Immune responsiveness was analyzed by PHA-stimulated thymidine uptake in mononuclear leucocytes and by serologic evidence of reactivation of the Epstein-Barr virus (EBV). We documented significant declines in in vitro PHA-induced lymphocyte transformation (-35%; p less than 0.05) and subjective well-being (-19%; p less than 0.05) from orientation to BCT with corresponding, significant increases in perceived stress (+32%; p less than 0.05). Despite significantly altered in vitro immune responsiveness, there was no serologic evidence of EBV reactivation nor was there an association between these measures and risk of illness as determined by medical chart review and self-reported symptoms. These results suggest that reduced in vitro immune responsiveness during a moderate stressor may not necessarily lead to an increased risk of infection and/or reactivation of EBV in normal individuals.