How does physician advice influence patient behavior? Evidence for a priming effect.

OBJECTIVE: To explore a potential "priming effect" of physician advice on patient responses to behavioral change interventions. DESIGN: Randomized controlled trial with a 3-month follow-up. SETTING: Four community-based group family medicine clinics in southeastern Missouri. PARTICIPANTS: Adult patients (N = 915). INTERVENTIONS: Printed educational materials designed to encourage patients to quit smoking, eat less fat, and increase physical activity. MAIN OUTCOME MEASURES: Recall, rating, and use of the educational materials; changes in smoking behavior, dietary fat consumption, and physical activity. RESULTS: Patients who received physician advice to quit smoking, eat less fat, or get more exercise prior to receiving intervention materials on the same topic were more likely to remember the materials, show them to others, and perceive the materials as applying to them specifically. They were also more likely to report trying to quit smoking (odds ratio [OR] = 1.54, 95% confidence interval [CI] = 0.95-2.40), quitting for at least 24 hours (OR = 1.85, 95% CI = 1.02-3.34), and making some changes in diet (OR = 1.35, 95% CI = 1.00-1.84) and physical activity (OR = 1.51, 95% CI = 0.95-2.40). CONCLUSIONS: Findings support an integrated model of disease prevention in which physician advice is a catalyst for change and is supported by a coordinated system of information and activities that can provide the depth of detail and individualization necessary for sustained behavioral change.

Evolution of immunologic functions of the mammary gland and the postnatal development of immunity.

Physiologic delays in production of immune factors occur in mammals including Homo sapiens. This finding is counter to a basic tenet of biologic evolution, because such delays increase the risk of infections. The disadvantage is, however, offset by defense factors in milk of the species in whom the developmental delay occurs. Reciprocal relationships between the production of immune factors by the lactating mammary gland and the production of those defense agents during early infancy are found in all investigated mammalian species. Thus, the evolution of these processes is closely related. Certain immunologic components of milk are highly conserved, whereas others vary according to the species. The variations most likely evolved by genetic mutations and natural selection. In addition, the immune composition of mammalian milks is associated with developmental delays in the same immunologic agents. Furthermore, most closely related mammals, such as humans and chimpanzees, are most similar in the defense agents in their milks and the corresponding developmental delays in their immune systems. Defense factors in human milk include antimicrobial agents (secretory IgA, lactoferrin, lysozyme, glycoconjugates, oligosaccharides, and digestive products of milk lipids), antiinflammatory factors (antioxidants, epithelial growth factors, cellular protective agents, and enzymes that degrade mediators of inflammation), immunomodulators (nucleotides, cytokines, and antiidiotypic antibodies), and leukocytes (neutrophils, macrophages, and lymphocytes). Because of a lack of geographic/ethnic variation in the immunologic composition of human milk and corresponding immunologic delays in infants, these evolutionary processes seem stable. This is supported by investigations of diverse populations that indicate that this evolutionary outcome is highly beneficial to human infants.

Decreased interleukin-10 production by neonatal monocytes and T cells: relationship to decreased production and expression of tumor necrosis factor-alpha and its receptors.

The production of IL-10 by human neonatal blood mononuclear leukocytes (BML) stimulated with lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF-alpha), antibodies to CD3, or phorbol 12-myristate 13-acetate (PMA) was measured. The production of IL-10 by neonatal BML cultured with LPS or TNF-alpha was approximately 20 and approximately 15%, respectively, of adult BML. The combination of human recombinant TNF-alpha and LPS failed to augment IL-10 production in neonatal BML. The decreased production of IL-10 by neonatal leukocytes was not due to an autocrine feedback mechanism because only low concentrations of IL-10 were found in newborn sera. A connection with TNF-alpha could not be ruled out, because TNF-alpha production by LPS-stimulated newborn BML and the expression of TNF-alpha receptors on newborn monocytes were reduced. Mean +/- SD of concentrations of IL-10 in supernatants from adult and neonatal BML after stimulation with antibodies to human CD3 for 48 or 72 h were 914 +/- 386 and 178 +/- 176 pg/mL, respectively (p < 0.0001). In experiments with enriched populations of neonatal T cells, the addition of PMA failed to augment IL-10 production. This suggested that newborn T cells may be in a different state of activation than adult T cells Thus, IL-10 production in neonatal monocytes and T cells is reduced and this study suggests that the reduction may be secondary in part to regulatory processes involving TNF-alpha and its receptors.

Reversible Ca2+-dependent translocation of protein kinase C and glucose-induced insulin release.

It has been reported that protein kinase C (PKC) interacts at multiple sites in beta-cell stimulus-secretion coupling. Nevertheless, there is still controversy concerning the importance of this enzyme in glucose-induced insulin release. The present study was undertaken to clarify whether glucose, directly, or through changes in cytoplasmic free Ca2+ concentration, [Ca2+]i, could promote translocation of PKC from the soluble to the membrane compartment. Whereas glucose, which increases [Ca2+]i, did not affect long-term distribution of PKC activity between soluble and membrane fractions, this distribution was reversibly affected acutely by the Ca2+ concentration in the extraction media. Translocation of PKC to the membrane by incubation of HIT cells for 10 min in the presence of 20 nM phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) resulted in a 5-fold increase in glucose-induced insulin release. This was prevented by 50 nM concentration of the PKC inhibitor staurosporine, provided that the cells were exposed to the inhibitor before the phorbol ester. Cells pretreated with TPA demonstrated increased insulin secretion in response to glucose for several hours. This time course extended beyond the disappearance of [3H]TPA from the cells, which was complete after 1 h. Activation of PKC increased both average insulin release and the amplitude of oscillations 2-fold, but did not affect oscillation frequency. The stimulatory effect of increased PKC activity on insulin release was not matched by changes in [Ca2+]i. We suggest that stimulation of the pancreatic beta-cell with glucose promotes transient translocation of certain PKC isoforms from the cytoplasm to the plasma membrane as a direct consequence of the increase in [Ca2+]i. Such a translocation may promote phosphorylation of one or several proteins involved in the regulation of the beta-cell stimulus-secretion coupling. This results in potentiation of glucose-induced activation of insulin exocytosis, an effect then not mediated by an increase in [Ca2+]i per se. Hence, pulsatile insulin release can be obtained under conditions where overall [Ca2+]i does not change, challenging the view that oscillations in [Ca2+ ]i are indeed driving the oscillations in hormone release.

Cytokines in human milk: properties and potential effects upon the mammary gland and the neonate.

Epidemiologic and immunologic studies of breastfed and nonbreastfed infants and investigations of certain biologic activities in human milk led to the identification of immunomodulating agents in human milk. Among them were the cytokines interleukin-1 beta (IL-1 beta); IL-6, IL-8, IL-10, granulocyte-colony stimulating factor, macrophage-colony stimulating factor (M-CSF), tumor necrosis factor-alpha, interferon-gamma, epithelial growth factor (EGF), transforming growth factor-alpha (TGF-alpha), and TGF-beta 2. Interferon-gamma may originate from T cells in milk; EGF, TGF-alpha, TGF-beta, M-CSF, IL-6, and IL-8 may be produced by mammary gland epithelium. Based upon their known functions, we hypothesize that cytokines influence the development and immunologic function of the mammary gland and the neonate. Those in vivo functions remain to be defined by future investigations.

Deficient quantitative expression of CD45 isoforms on CD4+ and CD8+ T cell subpopulations and subsets of CD45RA(low)CD45RO(low) T cells in newborn blood.

Deficiencies in the quantitative expression of CD45RA and CD45RO on CD4+ and CD8+ T cells and in a population of CD45RA(low)CD45RO(low) T cells in blood from term newborn infants were found by flow cytometry. The relative frequencies of CD45RO on CD4+ T cells from adults and newborn infants were 72 and 58%, respectively. However, in newborn infants greater than 70% of T cells expressing CD45RO also expressed CD45RA. In addition, the quantitative expression of CD45RA and CD45RO on newborn T cells was significantly less than that found on adult blood T cells.

Interleukin-10 in human milk.

The concentrations of immunoreactive IL-10 in the aqueous fraction of 20 specimens of human milk obtained during the first 80 h of lactation and stored at -60 degrees C ranged from 66 to 9301 pg/mL (mean +/- SD, 3304 +/- 3127 pg/mL). IL-10 was present also in the lipid layer of milk. Gel filtration revealed that IL-10 was located in a high molecular weight fraction, where certain other cytokines in human milk have been found. In addition, immunoreactive IL-10 in milk increased after treatment with sodium taurocholate. Bioactive IL-10 was demonstrated by the finding that human milk inhibited [3H]thymidine uptake by human blood lymphocytes and that inhibition was partly overcome by concomitant incubation with antibodies to human IL-10. IL-10 mRNA but no protein product was found in cultured human mammary epithelial cells. Some IL-10 was associated with preparations of human milk leukocytes, but the data did not suggest that the cells were producing the cytokine. Bioactive IL-10 in a possible protected compartment suggests that IL-10 in human milk may have immunomodulating, antiinflammatory effects on the alimentary tract of the recipient infant.

Immunologic protection of the premature newborn by human milk.

During the past decade, considerable evidence has accrued regarding the immunologic uniqueness of human milk and of the important role that the immune system in human milk plays in protecting not only the mature, healthy newborn, but also the premature infant who is more prone to infections and the damage caused by inflammatory processes. However, there is a great deal more to learn about the prophylactic and therapeutic uses of human milk in low birth weight infants, including (1) the status of many of the host defense factors in preterm milk, (2) how to preserve the protective agents in human milk during processing and storage, (3) the dose and duration of treatment with human preterm or mature milk that will be needed to protect against a particular disorder, (4) whether non-maternal milk is as efficacious as maternal milk for these infants, and (5) in view of the concern of potential graft versus host reactions, whether it is desirable or contraindicated to maintain the leukocytes in human milk used to feed premature infants. These questions are not easily answered, but will be worthy considerations by neonatologists, clinical immunologists, epidemiologists, and others who are concerned with providing optimal nutritional/immunologic support for the premature infant.