Effect of maternal smoking on stress physiology in healthy neonates.

OBJECTIVE: To assess the impact of maternal smoking during pregnancy (MSDP) on the neonatal hypothalamic-pituitary-adrenal axis. STUDY DESIGN: In a prospective observational study, salivary cortisol and cortisone levels were measured at the fourth day of life during resting conditions and in response to a pain-induced stress event in healthy neonates whose mothers smoked cigarettes during each stage of pregnancy and compared with controls. RESULTS: Neonates in the control group (n=70) exhibited a physiologic stress response with a significant increase in cortisol (1.3 to 2.1 ng ml-1; P<0.05) and cortisone (11.8 to 17.8 ng ml-1; P<0.05) from baseline levels, whereas in neonates from mothers who smoked (n=33), cortisol (0.9 to 0.8 ng ml-1; P=0.77) and cortisone (11.5 to 13.0; P=0.19) stress response was not significantly different from baseline levels. A two-way analysis of variance confirmed these findings in both groups. CONCLUSIONS: Healthy neonates whose mothers smoked during pregnancy show a blunted stress response on the fourth day of life. Thus, MSDP leads to a dysregulation of the HPA axis with continued effects in neonatal life. This might explain long-term consequences of MSDP such as overweight, diabetes mellitus and modification of blood pressure control mechanisms in adult life.

Salivary leptin induces increased expression of growth factors in oral keratinocytes.

We investigated the influence of salivary leptin, purified by affinity chromatography, on the proliferation of human oral keratinocytes. Furthermore we determined the time- and dose-dependency of the incubation with salivary leptin on the production of epidermal growth factor (EGF) and keratinocyte growth factor (KGF), which are growth factors relevant to keratinocyte proliferation. The analysis was performed both intra- and extracellularly. The relationship between the three cytokines in cell proliferation was studied by successive blocking with specific antibodies. The incubation of oral keratinocytes with recombinant and native leptin led to a significantly increased, dose-dependent cell proliferation (P<0.001). A further significant increase in proliferation was observed after incubating the cells with sterile filtered saliva (P<0.001). The increase in proliferation could not be observed by simultaneous incubation with salivary leptin and specific antibodies against either leptin or KGF (P<0.001). We found a significant dose-dependency between leptin incubation and production of KGF and EGF at the RNA and protein level. Both cytokines were expressed intracellularly and released into the culture medium, where they could be quantified by ELISA. Furthermore, there was a dose- and time-dependent increase in the phosphorylation of STAT-1 and STAT-3, indicating that Ob-R(b) (the long form of the leptin receptor) expressed by the keratinocytes is functional. It is conceivable that the leptin-induced proliferation in keratinocytes is mediated by this signalling pathway. This is the first study to show a physiological role of salivary leptin as a growth factor for keratinocyte proliferation in the oral cavity. We could demonstrate its influence on the production of other growth factors essential for this proliferative effect. Based on the findings of our study we assume an important role for salivary leptin in wound healing within the vulnerable oral cavity.

Identification of leptin in human saliva.

Leptin is produced predominantly in adipose tissue but has recently also been found in gastric mucosa. It has been shown that the oral application of leptin induces neuronal activity in the brain stem of rodents. The objective of the present study was to identify this hormone in human saliva and to examine the production and stability of salivary leptin. We have demonstrated production of leptin in salivary glands and oral mucosa by RT-PCR, its storage by immunocytochemistry, and the release of the peptide by RIA. Chromatographic analysis and immunoblotting confirmed the identity of leptin. There is a strong linear correlation (r2 = 0.78) between leptin concentrations from simultaneously collected saliva and plasma samples (n = 61). Stimulation of saliva flow increases total leptin secretion up to 3-fold (P < 0.001). As to the stability of leptin in gastric fluid, we found the peptide was not degraded above pH 3.5. Additionally, salivary leptin remains stable up to 5 d at 4 C. With regard to the presence of leptin receptors in gastric mucosa, we suggest salivary leptin as being a possible ligand for gastric leptin receptors. Furthermore, the determination of leptin in saliva allows for noninvasive sample collection.

Relationship between salivary progesterone, 17-hydroxyprogesterone, and cortisol levels throughout the normal menstrual cycle of healthy postmenarcheal girls.

OBJECTIVE: To determine the usefulness of salivary P and 17 alpha-hydroxyprogesterone (17-OHP) for the assessment of ovarian function. In addition, salivary cortisol (F) levels were measured to assess the role of the adrenal cortex throughout the menstrual cycle. DESIGN: Prospective study. SETTING: Outpatients in hospital for children and adolescents. PATIENT(S): Thirty young women with regular menstrual cycles. INTERVENTION(S): Saliva collection in the early morning from day 1 of menstrual bleeding until next menses. MAIN OUTCOME MEASURE(S): Salivary P, 17-OHP, and F measured by RIAs. RESULT(S): During days 1-12 of the follicular phase, P and 17-OHP levels remained unchanged (P: 9-29.3 pg/mL; 17-OHP: 8-31 pg/mL). Thereafter, P increased exponentially from day 13 onward, reaching a plateau (mean +/- SEM, 70.1 +/- 9.0 pg/mL) between day 16 and 20, followed by a constant decrease until end of the cycle. The 17-OHP levels increased between day 14 and 17 (maximum: 45.8 +/- 4.5 pg/mL), decreasing rapidly thereafter. The F levels remained unchanged (follicular: 7.5 +/- 1.1 ng/mL; luteal 7.2 +/- 1.1 ng/mL). There was a significant correlation between P and 17-OHP (r(2) = 0.43; P<.001). When calculating ratios of P/F and 17-OHP/F, linear regression yielded a much stronger correlation (r(2) = 0.74; P<.001), although F did not show any correlation to P or 17-OHP. CONCLUSION(S): Changes in salivary 17-OHP levels throughout the menstrual cycle reflect ovarian but not adrenal function.

Stability of salivary steroids: the influences of storage, food and dental care.

We studied influences of dental care, food and storage on the reproducibility of salivary steroid levels. Cortisol (F), 17OH-progesterone (17OHP) and Progesterone (P) were measured using adapted commercial radioimmunoassays. Saliva samples of healthy adults (n = 15; m:8; f:7) were collected directly before and after dental care, and directly before and after breakfast with various foodstuffs. A second experiment investigated stability of steroids under different storage conditions. Four series of identical saliva portions (I: Native saliva; II: Centrifuged saliva; III: Saliva with trifluor acetate (TFA); IV: Saliva with 0.5% NaN(3)) were stored at room temperature and at 4 degrees C for up to three weeks. To demonstrate influences of repeated thawing and re-freezing of saliva on steroid values, saliva samples (n = 15) were divided into identical portions. These portions were frozen and re-thawed up to 5 times before measurement. Neither dental care nor intake of bread or milk effected the reproducibility of F, 170HP, and P. Steroid levels decreased significantly in the course of three weeks under different storage conditions (P < 0.001). This decrease was clinically relevant from the second week onward, with exception of NaN(3) treated samples. After repeated freezing and re-thawing 17OHP and P decreased slightly (about 5%). Only F decreased significantly after the third thawing (P < 0.001). The results show the usefulness of standardized handling of saliva samples for improving reproducibility and reliability of salivary steroid measurements.

High school cross country running injuries: a longitudinal study.

OBJECTIVE: To determine the incidence rate of injury among high school cross country runners over a 15-year period. DESIGN: Prospective-longitudinal. SETTING: Twenty-three high schools in western Washington State under the surveillance of the University of Washington Athletic Health Care System between 1979-1994. PARTICIPANTS: One hundred and ninety-nine cross country teams. MAIN OUTCOME MEASURE: Injuries resulting from running in a cross country practice or meet. RESULTS: There were 1,622 injuries for an overall injury rate of 13.1/1,000 athletic exposures (AEs), i.e., participation of a runner in a practice or meet. Girls had a significantly higher overall injury rate (16.7/1,000 AEs) than boys (10.9/1,000 AEs) (p < 0.0001). Girls also had significantly higher injury rates than boys for both initial (p < 0.0001) and subsequent injuries (p < 0.0001), especially those at the same body location (p = 0.0001). This difference in risk estimates was consistent over a 15-year period. Nearly three-fourths of the injuries resulted in < or =4 days of disability. Overall, higher rates of initial injuries were reported during practices (9.2/1,000 AEs) than in meets (7.8/1,000 AEs) (p = 0.04). Shin injuries had the highest overall rates of new injury (1.9/1,000 AEs) and reinjury at the same body location (53.9/1,000 AEs). Girls had significantly higher initial injury rates than boys for shin (p < 0.0001), hip. and foot injuries (p < 0.01), and higher reinjury rates for knee. calf, and foot injuries, respectively (p < 0.05). CONCLUSION: The results of this study suggest that girl cross country runners are at higher risk of injury and reinjury than boy cross country runners.