Robert T. Chatterton

Modulation of attentional inhibition by norepinephrine and cortisol after psychological stress

Two of the most salient physiological responses to stress are increased norepinephrine (NE) and cortisol (CORT) activities. However, it is unclear how these neurochemical events affect cognition, especially attention. We examined the effects of mild psychological stress on selective attention, as assessed by the negative priming (NP) paradigm. Salivary measures of the stress hormone CORT and alpha-amylase (a correlate of NE) were assayed to probe the relationship between the stress response and attentional inhibition. Healthy subjects (N = 20) engaged in the attention task, which was then followed by 15 min of a stressful video game before a return to the attentional task. Baseline saliva samples were obtained before the experiment began, 1 min after the video-game stressor, and 20 min post-stress. Subjects showed a significant reduction in NP and a decrease in reaction time (RT) after the video game. Moreover, alpha-amylase levels increased significantly after the stressor, indicating the role of NE in the acute stress response. While CORT levels remained unchanged after stress, CORT correlated significantly with both NP scores and RT after the stressor. These results imply that mild psychological stress can significantly alter attentional processes. Given the increase in alpha-amylase and the correlation between attention and CORT after stress, it seems likely that attentional processes are under tight control by brain systems which mediate the fight-or-flight response.

Salivary estradiol and progesterone levels in conception and nonconception cycles in women: evaluation of a new assay for salivary estradiol☆

OBJECTIVEnTo determine the usefulness of salivary E2 and progesterone for noninvasive assessment of ovarian function.nnnDESIGNnProspective study of salivary hormone levels in women planning a pregnancy.nnnSETTINGnDepartment of Obstetrics and Gynecology at Northwestern University Medical School in Chicago, Illinois.nnnPATIENT(S)nFourteen women aged 23-39 years with regular menstrual cycles who were planning a pregnancy.nnnINTERVENTION(S)nNone.nnnMAIN OUTCOME MEASURE(S)nSalivary estradiol and progesterone concentrations.nnnRESULT(S)nThe sensitivity of the E2 assay is 2.0 pmol/L; the interassay coefficient of variation was 5.2% (mean value 17 pmol/L). Recovery of E2 added to saliva was 106%. The correlation with simultaneous serum samples was 0.71. Menstrual cycle patterns contained a preovulatory depression and a midcycle surge. By comparison with nonconception cycles, the luteal phases of conception cycles had significantly elevated salivary E2 within the first 5 days after ovulation. Salivary progesterone was significantly elevated but not until 10 days after ovulation.nnnCONCLUSION(S)nSalivary measurements of E2 and progesterone can be used as noninvasive methods for assessment of ovarian function. Salivary specimens can be collected at home and brought to the laboratory for analysis, obviating the need for frequent phlebotomy. The sensitivity and precision of the salivary E2 assay make it comparable with assays of serum E2 for assessing changes in hormone levels.

Comparison of Milk Output Between Mothers of Preterm and Term Infants: The First 6 Weeks After Birth

This study reports the temporal pattern of milk output in 2 groups of lactating mothers during the first 6 weeks postpartum. A study aim was to examine if the average milk output for postpartum days 6 and 7 (baseline) predicts milk adequacy at week 6 postpartum. Mothers of preterm (= 31 weeks) infants (n = 95) used mechanical expression to initiate and maintain their milk supply; mothers of a singleton healthy term infant (n = 98) fed their infant at the breast. Baseline milk output was predictive of milk adequacy, defined as = 500 mL/d at week 6 (P = .000). Preterm mothers were 2.81 times more at risk of not producing adequately than term mothers were. Study findings suggest that interventions that promote the initiation and maintenance of an adequate milk supply during the first week postbirth are critical.

Effects of pumping style on milk production in mothers of non-nursing preterm infants.

Milk production was examined in 39 lactating mothers of non-nursing preterm infants from 2 tertiary care centers. The purposes of this study were (1) to compare milk production of those using sequential single (SEQ) or simultaneous double (SIM) breast-pumping regimen, and (2) to examine the relationship of selected variables to inadequate (<3500 g/week) and adequate (>3500 g/week) milk production. In multivariate analysis, mothers using SIM produced a similar amount of milk by weight during weeks 2 to 5 postpartum compared to those using SEQ. A logistic regression model including frequency of kangaroo care, frequency of pumping, high versus low income, and previous breastfeeding experience was predictive of mothers producing adequate versus inadequate milk volume 79% of the time. All of the mothers producing >3500 g at week 2 produced adequate amounts of milk at weeks 4 and 5. None of the mothers producing < 1700 g at week 2 reached adequate production by weeks 4 and 5. Of the remaining mothers who produced 1700 g to 3500 g at week 2, 54% achieved adequate production during weeks 4 and 5 postpartum.

Initiation and frequency of pumping and milk production in mothers of non-nursing preterm infants.

This secondary data analysis examined if time of initiation of milk expression and pumping frequency influenced milk weight weeks 2-5 postpartum. Of the 39 subjects in the convenience sample, 20 were in the early initiating (EI) group, (n = 12 high frequency [HF], n = 8 lowfrequency [LF]), and 19 were in the late initiating (LI) group, (n= 7HF, n = 12LF). The EI group initiated pumping = 48 hours after birth; the HF group pumped a minimum of 6.25 times daily. A two-way analysis of variance indicated that milk weight was significantly higher in the HF as compared to the LF group. While there was no significant difference in milk weight between the EI and LI groups, therewas a significant interaction between frequency and initiation. Milk weight for the LF group appeared to be positively influenced by the initiation of mechanical expression soon after birth.

The Effects of a Low-Fat/High-Fiber Diet on Sex Hormone Levels and Menstrual Cycling in Premenopausal Women: A 12-Month Randomized Trial (the Diet and Hormone Study)

Reduction of cumulative exposure to endogenous ovarian steroid hormones is a postulated method for reducing the risk of carcinoma of the breast and other malignancies. Although there are data from trials evaluating the effect of low‐fat and high‐fiber diets on sex hormone levels in premenopausal women, to the authors knowledge none of these trials has combined a relatively large number of participants, follow‐up of > 2–3 months, parallel controls receiving a usual diet, and careful timing of blood sampling within the menstrual cycle.

Primary and secondary mediators' influence on milk output in lactating mothers of preterm and term infants.

This study examined potential primary mediators, such as intended length to breastfeed, maternal education, income, and infant gestation, and secondary mediators, such as early frequency of breast stimulation, early milk output, and supplementation with artificial milks that may influence milk output in mothers of preterm and term infants the first 6 weeks postpartum. Analysis suggested that for mothers of a preterm infant (n = 95), the primary mediators, income and infant gestation, and the secondary mediators, early milk output/d and early frequency/d, accounted for 53.5% of the variance in milk output/d at week 6. For mothers of a term infant (n = 98), the primary mediator, income, and secondary mediators, early milk output/d and supplementation, accounted for 48.4% of the variance in milk output/d at week 6. Further research is needed to determine what early interventions may improve milk output in mothers at risk for lactation failure. Journal of Human Lactation. 21(2):138-150.

Sequential, randomized trial of a low‐fat, high‐fiber diet and soy supplementation: Effects on circulating IGF‐I and its binding proteins in premenopausal women

Despite evidence supporting the involvement of the IGF system in the development of breast and other cancers, the major determinants of interindividual variability in circulatory IGF‐I levels are not well understood. Previous research has pointed to important genetic influences as well as dietary effects through marked calorie or protein restriction. We conducted a randomized trial to determine the effects of 2 dietary patterns on serum IGF‐1, IGFBP1 and IGFBP3 in free‐living premenopausal women: phase 1, an isocaloric low‐fat, high‐fiber (LFHF) vs. usual diet, and phase 2, a soy supplement either with or without isoflavones (soy+IF vs. soy–IF). Participants completed 12 menstrual cycles on phase 1 and then were randomly assigned to a soy supplement for 3 cycles while maintaining the phase 1 diet. Before and after each phase, 154 women provided serum. We found no difference in the change in IGF‐I, BP1 or BP3 in the LFHF group compared to the usual diet group. In phase 2, there were no differences in any IGF protein between the soy+IF and the soy–IF groups or any evidence of interaction between isoflavone exposure and the background diet. However, there was a small but statistically significant decrease (2.3%) in BP3 and an increase in the IGF‐I:BP3 molar ratio among all 153 subjects following either soy supplement. These changes were correlated with changes in intake of calcium, total vegetable protein and soy. The results are compatible with previous data suggesting that increases in dietary calcium, protein and soy, in particular, could increase circulating levels of bioavailable IGF‐I.

Direct radioimmunoassay of progesterone in saliva.

We have developed a simple, direct radioimmunoassay for progesterone in saliva. The correlation coefficient (r) between the direct assay and an extraction procedure was 0.92 (n = 65, P < 0.001), and the correlation between concurrent serum and salivary progesterone concentrations in the luteal phases of menstrual cycles of 48 women was 0.75 (P < 0.001). Whereas certain polystyrene and polyethylene vials and tubes were found to bind and remove up to 87% of the progesterone from saliva, other plastic and glass surfaces were satisfactory for the procedure. Intraassay and interassay CVs from values greater than 300 pmol/L were 12.0 and 12.4%, respectively. The assay sensitivity was 48 pmol/L. Collection of saliva is a more convenient and less invasive technique for frequent sample collection than phlebotomy, and is useful for monitoring ovulation and assessment of luteal function in women clinically.

Growth factors in expressed prostatic fluid from men with prostate cancer, BPH, and clinically normal prostates

Although growth factors such as epidermal growth factor (EGF), transforming growth factor (TGF)‐α, and TGF‐β are important regulators of prostate cell growth in vitro and in animal models, evidence to support their role in human prostate cancer development remains sparse. We previously showed that men without prostate cancer have concentrations of EGF and TGF‐α in expressed prostatic fluid (EPF) that are individually distinct and stable over time. This study addressed whether growth factor levels in EPF are associated with the presence or progression of prostate cancer.