注射Bestatin对幼年大鼠分辨学习的影响

以Ｓｐｒａｑｕｅ－Ｄａｗｌｅｙ大鼠为实验动物,从出生后第１天起,每日皮下分别注射氨基肽酶的抑制剂Ｂｅｓｔａｔｉｎ（１ｍｇ／ｋｇ（ｂ．ｗ））以及钠络酮（２ｍｇ／ｋｇ（ｂ．ｗ）＋Ｂｅｓｔａｉｎｇ（１ｍｇ／ｋｇ（ｂ．ｗ））,对照组注射等量的生理盐水,连续注射１４天,观察：１６日龄幼鼠的吸乳迷津分辨学习（ＡＤＬ）,３０日龄Ｙ迷津明暗分辨学习（ＡＤＬ）,３０日龄Ｙ迷津明暗分辨学习（ＢＤＬ）行为,４５日龄幼鼠     

Early life environment and adult height: The case of Chile

In this paper, we analyze the relationship between adult height and early-life disease environment, proxied by the infant mortality rate (IMR) in the first year of life, using cohort-region level data for Chile for 1960–1989. IMRs show a remarkable reduction of 100 points per thousand over this thirty-year period, declining from 119.4 to 21.0 per thousand. We also document a 0.96 cm increase in height per decade.We find that the drop in IMRs observed among our cohorts explains almost all of the long-term trend in rising adult heights, and that per capita GDP does not appear to have any predictive power in this context. Results are robust in a variety of specifications, which include area and cohort dummies, an adjustment for internal migration, and urbanization rates. Our results point to the long-term effect of a public health policy.     

The protective effect of breast feeding in relation to sudden infant death syndrome (SIDS): II. The effect of human milk and infant formula preparations on binding of Clostridium perfringens to epithelial cells

Breast feeding is known to protect an infant against gastrointestinal pathogens and epidemiological studies indicate that compared to breast fed infants, formula fed infants are at a greater risk of dying from sudden infant death syndrome (SIDS). Many SIDS infants have symptoms of gastrointestinal infections prior to death and one gastrointestinal pathogen associated with SIDS is Clostridium perfringens. Studies have found that a significantly higher number of formula fed SIDS infants have C perfringens and its enterotoxin in their faeces compared to breast fed infants. The aim of the study was to compare the effects of human milk and infant formula on binding of C perfringens to epithelial cells. Two protocols were used to assess the effect of human milk and infant formula to inhibit binding of C perfringens to epithelial cells. Binding was assessed by flow cytometry. For the in vivo protocol which more closely represents interactions on the mucosal surface, breast milk enhanced bacterial binding but infant formula caused inhibition of binding; however for the in vitro method, both human milk and infant formula resulted in consistent enhancement of binding. Flow cytometry studies indicated that enhancement of binding was due to the formation of bacterial aggregates. Lewis(a) and Lewis(b) antigens, found in both breast milk and infant formula, inhibited C. perfringens binding in a dose dependent manner. The Lewis(a) and Lewis(b) antigens in human milk and infant formula can inhibit C. perfringens binding to epithelial cells. While infant formula reduced binding of C. perfringens to epithelial cells in the experiments carried out with the in vivo protocol, the protective effects of breast feeding in relation to colonisation with C. perfringens are more likely to be due to formation of bacterial aggregates. These findings have implications for improving infant formula preparations.     

Ecological correlates to social structure in two lemur species in Madagascar

In this study, I tested two hypotheses regarding the relationship of ecological variables (size, density, and distribution of patches) and infant developmental patterns to lemur social structure using two prosimian primates in Ranomafana, Madagascar: the rufous lemur (Eulemur fulvus rufus) and the red-bellied lemur (Eulemur rubriventer). Three predictions regarding the general effects of patch size and subgroup size on lemur feeding rates were supported: (1) Rufous lemurs used large patches; red-bellied lemurs used smaller patches; (2) larger subgroups of rufous lemurs used larger patches; and (3) rufous lemur feeding rates decreased significantly with increases in subgroup size and patch size, whereas size and patch size had no significant effect on red-bellied lemur feeding rates. However, food item size (fruit) had a more significant effect on rufous and red-bellied lemur feeding rates than either patch size or subgroup size. When similar-sized fruits were compared, rufous lemur feeding rates on small fruit were most affected by patch size, yet feeding rates on medium-sized fruit were most affected by subgroup size. Neither lemur species used patches in consistent ways seasonally. During periods of food abundance, rufous lemurs used many small, common, and clumped patches. In food scarcity periods, they used fewer, larger, rarer, and less clumped patches; groups migrated when food became most scarce. Red-bellied lemurs also used patches in variable ways, but these patterns were not linked with food availability. Finally, infant development patterns differed between lemur species; red-bellied lemur males cared for offspring and infants reached developmental landmarks faster than rufous lemur infants. Therefore, red-bellied lemur group size may be constrained by the need for additional infant care by other group members. In contrast, rufous lemur group size may be constrained by patch availability during the most critical period of food scarcity. © 1996 Wiley-Liss, Inc.     

Analysis of infant carrying in large,well-established family groups of captive marmosets (<Emphasis Type="Italic">Callithrix jacchus</Emphasis>)

To assess the pattern of infant carrying across time and family members, we counted which animals in 13 well-established family groups of captive-bred marmosets (Callithrix jacchus) carried neonates during the first 8 weeks of life. The neonates were carried almost continuously for the first 3 weeks and then spent progressively more time independently. The mother did most of the carrying for the first 2 weeks, her contribution rising from day 1 to day 3 and declining thereafter. The contribution of the father was high on day 1, declined during the first week, and then rose to a peak in the fourth week. The contribution of the siblings rose sharply during the first week and declined thereafter. There was no overall difference in amount of infant carrying by each parent. The contribution of each sibling was small although in these large families the total contribution by siblings was large. These data may differ from previous observations because the breeding pairs were very well established, the families were large, and all except the youngest animals were very experienced in rearing and carrying. These data emphasise the group-dynamic nature of infant carrying in a primate species.     

Elevated urinary testosterone excretion and decreased maternal caregiving effort in marmosets when conception occurs during the period of infant dependence

The proximate mechanisms that regulate transitions in mammalian female reproductive effort have not been widely studied. However, variation in circulating levels of the androgenic steroid hormone testosterone (T) appears to mediate a trade-off between investment in current and future offspring in males [Ketterson, E.D., Nolan, V., Jr., 1992. Hormones and life histories: an integrative approach. Am. Nat. 140, S33-S62; Ketterson, E.D., Nolan, V., Jr., 1994. Hormones and life histories: an integrative approach. In: L.A. Real (Ed.), Behavioral Mechanisms in Evolutionary Ecology, University of Chicago Press, Chicago, pp. 327-353; Ketterson, E. D., Nolan, V., Jr., 1999. Adaptation, exaptation, and constraint: A hormonal perspective. Am. Nat. 154S, S4-S25]. The purpose of this study was to investigate the possibility that T is also associated with transitions in the reproductive effort of females, by examining the relationship between urinary T excretion, maternal caregiving behavior, and the timing of the postpartum conception in female Wied's black tufted-ear marmosets (Callithrix kuhlii). We examined the maternal carrying effort and peripartum T profiles of six females across two conditions: (1) when they conceived during the period of infant dependence (DPID), such that gestation was coupled with lactation; and (2) when the same females conceived after the period of infant dependence (APID). We also assessed the relationship between postpartum T levels and caregiving effort. When female marmosets conceived DPID, they dramatically reduced their caregiving effort, and had higher levels of urinary T, relative to when they conceived APID. Further, the litter-to-litter changes in maternal caregiving effort that we observed were related to variation in urinary T excretion; as weekly levels of urinary T excretion increased, concurrent caregiving effort declined. Our results suggest that variation in T secretion may regulate transitions in female reproductive behavior, and that the regulation of male and female parental behavior may be mediated by homologous neuroendocrine mechanisms.     

Quantification of Bifidobacterium spp., Escherichia coli and Clostridium difficile in faecal samples of breast-fed and formula-fed infants by real-time PCR

To determine the influence of either exclusive breast-feeding or formula feeding on both composition and quantity of the gut microbiota in infants, we have developed real-time, quantitative PCR assays for the detection of Bifidobacterium spp. and Clostridium difficile. Furthermore, we have monitored the prevalence and counts of Escherichia coli by applying a previously described real-time PCR assay. We found all 100 infants tested to be colonized by Bifidobacterium spp. The bifidobacterial counts were comparable between the 50 breast-fed and 50 formula-fed infants with median values of 10.56 log10 and 10.24 log10 CFU g(-1) wet weight faeces, respectively. C. difficile was detected in 14% of the breast-fed and 30% of the formula-fed infants. In addition, the C. difficile counts were significantly lower in breast-fed infants than in the formula-fed group (median values of 3.28 log10 and 7.43 log10 CFU g(-1), respectively; p=0.03). The prevalence of E. coli in the breast-fed and formula-fed group was 80% and 94%, respectively. Also, the E. coli counts in colonized infants was significantly lower in the breast-fed infants than in the formula-fed group (median values of 9.11 log10 and 9.57 log10 CFU g(-1), respectively; p=0.004). We conclude that the prevalence and counts of C. difficile as well as E. coli are significantly lower in the gut microbiota of breast-fed infants than in that of formula-fed infants, whereas the prevalence and counts of Bifidobacterium spp. is similar among both groups.     

Relationship Between Infant and Mother Circadian Rest-Activity Rhythm Pre- and Postpartum,in Comparison to an Infant With Free-Running Rhythm

Some infants show a free-running rhythm in their rest-activity. We do not know why, nor do we know exactly what the entrainment factors are for the development of the normal 24-h rest-activity rhythm. Actigraphic recordings on 10 primiparae during late pregnancy and these mothers and their infants during the 2nd, 6th, and 12th wks after birth were made over 3–5 continuous days to investigate maternal and infant entrainment. One infant showed a free-running rest-activity circadian rhythm. In late pregnancy, the period in the autocorrelogram of the mother with the free-running infant was longer than the significant period of the mean autocorrelogram of the mothers with non-free-running infants. The finding of this study indicates the free-running rhythm of infant is not reset by maternal entrainment factors. (Author correspondence: nishihara-kk@igakuken.or.jp)     

The effects of social context on the hormonal and behavioral responsiveness of human fathers

We tested first-time fathers with their 22-month old toddlers to determine whether social context variables such as pre-test absence from the child and presence of the mother affected physiological measures associated with paternal responsiveness. Heart rate and blood pressure readings as well as blood samples to determine prolactin, testosterone and cortisol levels were taken before and after the 30-min father–toddler interactions. Fathers were tested on a day when they were away from their child for several hours before testing (‘without-child’ day) and on another day where they remained with their child throughout the day (‘with-child’ day). Most measures decreased over the 30-min test period but relative decreases were context-dependent. Men maintained higher prolactin levels when they were away from their children longer before testing on the ‘without-child’ day. Cortisol levels decreased during both tests and they decreased more on the ‘with-child’ day for men who had spent more time alone with their toddler before the test. Heart-rate and diastolic (but not systolic) blood pressure decreased more on the ‘with-child’ day than on the ‘without-child’ day. Fathers' testosterone levels decreased when their partners were less involved in the interactions. Compared to men with high responsiveness ratings on both days, men whose responsiveness increased after being away from their child on the ‘without-child’ day maintained higher systolic blood pressure and had a greater decrease in testosterone levels. We conclude that context may be more important in determining fathers' physiological responses to child contact than has previously been appreciated, particularly for some individuals.