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PubMed2000

Prevalence of Cryptosporidium, Giardia and Eimeria infections in post-weaned and adult cattle on three Maryland farms.

The prevalence of Cryptosporidium, Giardia and Eimeria, in healthy, asymptomatic, post-weaned and mature cattle was investigated on three Maryland farms. One farm, a dairy research facility, had 150 multiparous Holstein milking cows; 24 were examined and Cryptosporidium andersoni was detected in three (12.5%) but neither Giardia nor Eimeria was detected. The second farm, a commercial dairy, had 57 multiparous Holstein milking cows and an equal number of heifers. Of 19 cows examined, C. parvum, Giardia duodenalis, and Eimeria bovis and/or E. ellipsoidalis were detected in two (10.5%), two (10.5%) and one (5.26%) cow, respectively. Of 23 heifers examined, C. parvum, Giardia, and E. bovis and E. ellipsoidalis, was detected in two (8.7%), four (17.4%), and five (21.7%), heifers, respectively. The third farm, a beef cattle breeding and genetics research facility, had 180 7- to 9-month old purebred black Angus. Of 118 examined for C. parvum and Giardia, 34 (28.8%) and 44 (37.3%) were positive, respectively, of 97 examined for E. bovis and/or E. ellipsoidalis 32 (33.0%) were positive. These findings, based on a method with a minimum detection level of 100 oocysts of C. parvum/g of feces, which underestimates the number of infected cattle, clearly demonstrate the presence of low level, asymptomatic infections in post-weaned and adult cattle in the United States and indicate the potential role of such cattle as reservoirs of infectious parasites.

Animals↗
PubMed2002

Postpartum anoestrus is reduced by increasing the within-day milking to suckling interval in dual purpose cows.

In the dual purpose milk/beef production system practised in Mexico, the cows are milked once a day in the presence of the calf and then the calf suckles for the next 1-8 h. It was hypothesised that the imposition of milking and suckling in close succession contributes to the long postpartum anoestrous periods experienced by cows in this system. Therefore, separating these two inhibiting factors, by delaying the start of suckling after milking would lower the impact on the hypothalamus-hypophysial axis and allow it to recover more readily. This hypothesis was tested in two experiments using Bostaurus x Bosindicus cows which weighed 541.3 +/- 12.7 kg (mean +/- S.E.M.; experiment 1) and 537.8 +/- 10.6 kg (experiment 2) and had a body condition score of 5-6 (scale 1-9) at calving. The cows and calves were maintained on separate pastures and the cows were offered concentrate supplements. Experiment 1 was conducted in the dry season and cows were offered a daily supplement of 3 kg of 17% crude protein (CP) concentrates plus 1 kg molasses per cow. Experiment 2 was conducted during the wet season and the nutritional supplement consisted of only 1 kg of 17% CP plus 1 kg molasses per cow per day. Each experiment lasted for the first 100 days postpartum and the cows were not mated during this time. Cows were hand-milked once a day in the presence of the calf to stimulate milk let-down. In experiment 1, 30 multiparous cows were assigned at random by date of calving, to one of three treatments: controlled suckling (CS; n = 10), delayed suckling (DS; n = 10) and prolonged delayed suckling (PDS; n = 10). The suckling period on all treatments lasted for 2 h and started at 0 h (CS), 4 h (DS) or 8 h (PDS) after milking. In experiment, 34 multiparous cows were assigned at random to three treatments: CS (n = 11), PDS (n = 11) or prolonged delayed short suckling (PDSS; n = 12), in this last treatment the suckling period was reduced to only 30 min. In both experiments, one quarter of the udder of cows on treatment CS was not milked but all the udder was milked on the other treatments. Body weights of cows and calves and cow milk yields were recorded. Weekly blood samples were collected for plasma progesterone assay to detect the first postpartum corpus luteum. Data were analysed by ANOVA and chi-square test. Cows in experiment 1 had similar weight changes during the first 100 days postpartum. Milk production was higher for DS (8.0 +/- 0.7 kg per day) and PDS (7.0 +/- 0.5 kg per day) cows than for CS (5.2 +/- 0.7 kg per day) cows (P < 0.01). Calf daily gain was greater (P < 0.05) for PDS (827 +/- 35 g per day), than CS (702 +/- 26 g per day) or DS (715 +/- 29 g per day). The proportion of cows ovulating during the first 100 days postpartum were 50.0, 70.0 and 100.0%, for CS, DS and PDS, respectively (P < 0.05). The intervals from calving to first significant rise in progesterone were 70.4 +/- 1.6, 72.1 +/- 1.3 and 64.6 +/- 1.5 days for CS, DS and PDS (P > 0.05), respectively. In experiment 2, cow body weight during the first 100 days postpartum did not differ between treatments. Milk production was not significantly different between CS (7.3 +/- 1.0 kg per day) and PDSS (6.8 +/- 1.0 kg per day), but was higher (P < 0.05) for CS than PDS (5.2 +/- 1.0 kg per day). Calf daily gain was lower for CS (576 +/- 31 g per day; P < 0.05) than PDS (779 +/- 38 g per day) and PDSS (780 +/- 20 g per day). The proportion of cows ovulating was higher (P < 0.05) for treatments PDS (100%) and CS (81.8%) than PDSS (50%). Calving to first ovulation interval was shorter (P < 0.05) for PDS (57.3 +/- 4.5 days) and PDSS (49.7 +/- 3.0 days) cows than CS (72.1 +/- 3.5 days) cows. It is concluded that delaying suckling for 8 h after milking, increases the proportion of cows ovulating within 100 days of calving, shortened the calving to first ovulation interval and improved calf performance without adversely affecting cow milk yield or body weight change.

Anestrus↗
PubMed1998

Birth order, estrogens and sex-ratio adaptation in African wild dogs (Lycaon pictus).

Because the sex of mammals is chromosomally determined, populations generally produce a similar proportion of males and females. However, it has been recognized for more than century that individuals might increase their fitness by over-producing offspring of one sex, under certain conditions. Small biases in the secondary sex ratio are seen in many vertebrates. Here, we report that the sex ratio of primiparous African wild dogs (Lycaon pictus) is strongly biased in favor of sons (63%), while multiparous females produce an excess of daughters (64%). The direction of these biases is predicted by individual females' need for subordinate helpers. For humans, elevated estrogens have been hypothesized to bias the secondary sex ratio toward males. Consistent with this hypothesis, primiparous female wild dogs had basal estrogen levels double those of multiparous females.

Animals↗
PubMed2000

Seasonal effects on puberty and reproductive characteristics of female Chios sheep and Damascus goats born in autumn or in February.

Ten Chios ewe lambs and 10 Damascus she-kids born in October-November and similar numbers born in February along with eight multiparous females from each species, were used to examine pubertal events and reproductive seasonality. Reproductive activity was monitored by determining serum progesterone concentrations once a week for 12 months. The mean date of onset of ovulation (puberty) in autumn-born Chios females (7 August) was earlier (p<0.05) than in February-born ones (11 September) though the onset of regular cyclicity was not significantly different between the two groups (30 August and 19 September, respectively). The age and live weight at puberty in autumn-born females was higher (p<0.01) than in February-born ones, the respective values being 43.3 weeks and 50.1kg, versus 29.9 weeks and 42.0kg. All animals, irrespective of time of birth, started ovulating after the summer equinox. Multiparous Chios ewes had reproductive cycles covering most time of the year with acyclic periods during spring and summer. In ewe lambs, about half of the animals ceased cycling during the second half of winter and in spring, while the rest continued cycling. The total number of cycles detected over the experimental period was lower (p<0.05) for February-born (n=9.4) compared with autumn-born females (n=13.7) and adult ewes (n=17.1). In Damascus she-kids born in autumn or in February, onset of puberty was at the same time in the following autumn, the respective mean date for the two groups being 1 November and 27 October. For autumn-born animals, age (48.4 weeks) and live weight (53.8kg) at puberty were higher (p<0.01) than for those born in February (37.3 weeks, 42.9kg). Reproductive cycles in adult goats started in the second half of September and continued until the end of March. Most young goats (75%) had their last seasonal cycle in February and the rest in March. The total number of cycles was higher (p<0.01) in adult (n=8.1) than in young goats born either in autumn (n=6.3) or in February (n=5.7). It is concluded that reproductive development and puberty in Chios female sheep are mostly under seasonal influences though age and body weight are also contributing factors. This breed has a long reproductive season with some animals cycling throughout the year. The Damascus female goat is strictly seasonal with distinct periods of reproductive cyclicity and inactivity. Puberty attainment of Damascus females born in autumn or in February is at the same time the following autumn.

Journal Article↗
PubMed1998

[Factors influencing the duration of breast feeding. A study of 150 women].

BACKGROUND: The duration of breast feeding has not yet been thoroughly described in France. A prospective survey has been performed on 150 breast feeding mothers to determine its duration. The objective of this study was to analyse predicting factors of this duration. METHODS: A questionnaire including sociological, psychological and medical variables was completed by the mothers and fathers. After discharge, the mothers were contacted every month by a physician until the completion of weaning. RESULTS: The median duration was 10 weeks. By univariate analysis, several variables were associated with a longer duration: decision to breast feed before pregnancy (12 weeks vs 9 weeks; P < 0.01), multiparity (17 weeks vs 12 weeks, P < 0.05), high paternal social level (14 weeks vs 9 weeks, P < 0.001), high maternal education level (12 weeks vs 9 weeks; P < 0.05), mother's idea of "bad" milk (9 weeks vs 30 weeks; P < 10(-6), satisfied mothers (11 weeks vs 2 weeks; P < 0.001), motivation to breast feed (P < 0.05), baby and mother in the same room during the night (13 weeks vs 10 weeks; P < 0.05), and formula supplementation (6 weeks vs 13 weeks; P < 0.01). The mother's return to work was related to a decline in the breast feeding rate at 12 weeks, yet working women generally breast fed the most frequently before returning to work, and many women breast fed and worked concomitantly. A Cox multivariate analysis took into account six significant variables: "bad" milk (lower duration), mother who had been fed, mother satisfied with breast feeding, multiparity, high maternal education, closer proximity of baby to mother (longer duration). DISCUSSION: The duration in our study is longer than in other studies in France. Predictive factors are sociological, linked to maternal education, and psychological, with antecedent of mother breast feeding and decision before pregnancy. The role of the mother's occupation was not very important because working women are generally at a higher social level. The role of the father was analysed, as well as the role of professional workers, family and breast feeding women's associations. CONCLUSION: Factors of breast feeding duration can be somewhat modified, but it is necessary to respect the plans of both the mother and the father. However, early assistance in the hospital and after discharge can help parents realize their plans for prolonged breast feeding and helps obviating the cessation of 20% of mothers during the 1st month.

Adult↗
PubMed2000

Pregnancy, fertility, and disease course in patients with Crohn's disease and ulcerative colitis.

Pattern recognition of the long-term disease course before, during, and after pregnancy can provide us with data about the influence of pregnancy on IBD, and vice versa. Determinants that predict an indolent versus an aggressive disease course are currently being sought. Our intention is to analyze the disease course during pregnancy in an EU-IBD inception cohort of 1200 patients diagnosed from 1991 to 1993 and followed up for 10 years. We also attempt to evaluate such factors as smoking and medication and to predict pregnancy course and fertility in IBD as well as in a cross-sectional study of members of the patient organization EFCCA. One of the questions that arose was: what factor is responsible for the observation that pregnancy decreases the incidence of relapses and the development of fibrostenotic lesions? Relaxin and the glycoprotein YKL-40 are validated in the cohort. The protein relaxin, produced by the corpus luteum during pregnancy, increases the laxity of fibrous tissue. Collagen fibers are dissolved and disorganized. As maternal rejection of the fetus does not occur, a protein from the fetal lymphocytes most likely decreases the maternal lymphocyte response. Multiparity may lead to subtle, acquired immune deficits. Glycoprotein YKL-40, which causes fibrosis in RA and cirrhosis, is speculated to be lower in multiparous women than in nonpregnant women due to the fetal lymphocytes that secrete a protein that is a potential immune modulator. Knowledge gained from future EC-IBD studies may result in new legislation (e.g. regarding adoption) that can benefit IBD patients throughout Europe.

Journal Article↗
PubMed2002

[Choriocarcinoma in Senegal: epidemiology, prognosis and prevention].

OBJECTIVE: The objective of this study was to define the epidemiological profile of choriocarcinoma in Senegal, to evaluate its prognosis and to submit a better way of prevention of this pathology in an area with poor medical care. MATERIAL AND METHOD: It was a retrospective case-control study of all choriocarcinomas diagnosed from January 1st to December 31st 2000 at Dakar university teaching hospital. The witnesses were chosen among patients who had had molar abortion at the same time as the cases at study and had not developed the pathology after at least 12 months of aftercare. The stability of association was checked by calculating the confidence interval in 95% by Miettinen method and using Chi 2 test of Pearson with a risk factor alpha under 5% or Fischer test; the prognosis survival factors were compared by using logrank test. RESULTS: Among the 1098 patients in follow-up treatment after molar abortion, 61 choriocarcinomas were diagnosed with an incidence of 5.5%. The epidemiological profile was a great multiparous (40 years old or more) with low socio-economical level, 51% of the diagnosed cases are made in the metastasis stage. The prognosis was marked by a complete remission in 37.7% and by global lethality in 49.2%; the average survival was about 48 months. DISCUSSION AND CONCLUSION: The risk factors of choriocarcinoma among patients who had a molar abortion were represented by an age superior or equal to 40 years old, high multiparity and preservation of the uterus after molar abortion. To improve the prognosis in a country with low medical care, we recommend to widen preventive hysterectomy indications after molar abortion among patients with risk factors of choriocarcinoma.

Adult↗
PubMedDate not supplied

Length of normal labor in women of Hispanic origin.

Emanuel Friedman in the 1950s established means and statistical guidelines for normal lengths of labor. The childbearing population in the United States has changed considerably since Friedman's research was conducted. This study documented the duration of labor in a cohort of 240 Hispanic women who had normal vaginal births of singleton term infants from January 1995 through December 1998 and compared these results with the mean duration of the first and second stages of labor as established by Friedman. The mean duration of the active phase first stage labor duration for nulliparous Hispanic women was 6.2 hours, and for multiparous Hispanic women was 4.4 hours, both significantly longer than Friedman's group (P <.01). The mean duration of the second stage of labor in nulliparous Hispanic women was 54.2 minutes and for multiparous Hispanic women was 22.2 minutes, not significantly different from Friedman's group (P =.5 and P =.09, respectively).

Adolescent↗
PubMed2002

The impact of parity on the incidence of HELLP syndrome and small for gestational age infants in hypertensive pregnant women.

OBJECTIVES: To determine whether maternal and fetal complications such as HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome and the incidence of small for gestational age infants in women with preeclampsia and gestational hypertension differ with both gravidity and parity. STUDY DESIGN: The charts of 441 hypertensive women, 182 with preeclampsia and 259 with gestational hypertension, presenting for delivery at B.C. Women's Hospital were retrospectively reviewed. Multiple clinical parameters, including gestational age at presentation, the incidence of small for gestational age (SGA) infants, HELLP syndrome, and the severity of pre-eclampsia, were compared among three groups of women: (A) primigravid primiparous, (B) multigravid primiparous, and (C) multiparous. Mean values between the groups were compared using analysis of variance with pair-wise comparison using the Tukey test. RESULTS: The incidence of HELLP syndrome among the women with preeclampsia was similar in groups A and B (35% and 50%, respectively), but significantly lower (p < 0.012) in group C (19%). The incidence of small for gestational age infants among the women with preeclampsia was similar for groups A, B, and C (27%, 31%, and 19%, respectively). In the gestational hypertensive group the incidence of SGA infants was similar for groups A, B, and C (14%, 11%, and 12% respectively). CONCLUSIONS: The preeclamptic primigravid primiparous and multigravid primiparous groups behaved similarly in their clinical expression of hypertensive complications but differed from the multiparous group by having a higher incidence of HELLP syndrome. The incidence of complications in hypertensive pregnant women varied by parity but not by gravidity. The gestational hypertensive groups did not differ in their clinical expression of hypertensive complications.

Adult↗
PubMed2003

Parental and birth characteristics in relation to testicular cancer risk among males born between 1960 and 1995 in California (United States).

OBJECTIVE: We explored birth and parental risk factors for testicular cancer, examining risk factors for all testicular cancers and by histologic type. METHODS: We linked 1645 testicular cancer cases to live singleton birth certificates, selecting three random controls per case, matched by sex and date of birth. We used conditional multiple logistic regression to assess the mutually adjusted effects of parental and birth characteristics on testicular cancer risk. RESULTS: Sons of Black mothers had a lower risk than those of White mothers (adjusted odds ratio (AOR) = 0.38, 95% confidence interval (CI)=0.12, 1.22). Increasing maternal age was associated with an increased risk in offspring (AOR=1.03 for each year of maternal age, 95% CI=1.01, 1.05). Sons of primiparous and low-multiparous women had increased risks compared to sons of high-multiparous women (AOR=1.22, 95% CI=1.04, 1.44; and AOR=1.31, 95% CI=1.12, 1.54, respectively). Among seminomas, term infants with birth weights of 1500-2499 g had a higher risk compared to term, normal birth weight infants (AOR=2.69, 95% CI=1.40, 5.17; p-value for homogeneity=0.008). CONCLUSIONS: Markers of higher estrogen exposure in the mother (age and parity) are associated with increased testicular cancer risk, and factors associated with fetal growth retardation may be associated with seminoma testicular cancer.

Adolescent↗
PubMed2001

Maternal smoking and gestational age in twin pregnancies.

BACKGROUND: A twin pregnancy imposes greater demands on maternal physiology and smoking may thus be associated theoretically with a greater risk of preterm delivery than in singleton pregnancies. POPULATION AND METHODS: From 1989 to 1996 all women who booked for antenatal care at the Department of Gynecology and Obstetrics, Aarhus University Hospital, Denmark were asked to fill in two questionnaires. Apart from smoking habits, these questionnaires provided information on medical and obstetric history together with information on sociodemographic and other lifestyle variables. Gestational age at delivery was calculated from ultrasonographically determined fetal biparietal diameter and information about the last menstrual period. Only women carrying twins were included in the present study (n=401). RESULTS: Mean gestational age was 5 days (95% CI 1-9 days) shorter among smokers compared with non-smokers. Among non-smokers mean gestational age was 261 days (+/-18), among women who smoked 1-9 and 10+ cigarettes per day 257 days (+/-23) and 255 days (+/-20), respectively. The overall risk of preterm delivery (< 37 weeks) and delivery before 34 completed weeks was 1.3 (95% CI 0.9-2.2) and 1.4 (95% CI 0.8-2.4), respectively. Primiparous women had shorter gestational age than did multiparous women. Still, among primiparous as well as among multiparous women gestational age decreased with smoking. Adjustment for maternal age, height and prepregnancy weight, alcohol and caffeine intake, marital status, education, occupational status, preterm birth in previous pregnancies, and in vitro fertilization in the present pregnancy did not change the results. CONCLUSIONS: Smoking has a substantial effect on mean gestational age in twin pregnancies, and a dose response like relationship is present.

Adolescent↗
PubMed2003

Intrapartum influences on cesarean delivery in multiple gestation.

OBJECTIVE: To evaluate which intrapartum factors influence the method of delivery in a group of twin pregnancies eligible for vaginal delivery. STUDY DESIGN: Over a 10-year period, 967 consecutive twin pregnancies at gestational age >/=32 weeks with twin A presenting as a vertex and eligible for vaginal delivery were reviewed. Excluded were 40 (4.1%) patients who underwent a repeat and elective cesarean section. All patients who underwent a cesarean section were placed into one of two groups according to the method of delivery of both twins: group 1, cesarean section/cesarean section delivery; and group 2, vaginal/cesarean section delivery. The impact of the following intrapartum factors on the type of delivery were assessed: (1) presentation of the 2nd twin: vertex vs. breech vs. other; (2) experience of the obstetrician: </=euro 10 years vs. > 10 years in practice; (3) multiparity: nulliparous vs. multiparous; (4) incidence of epidural usage; (5) induction vs. spontaneous labor; and (6) difference in fetal weight between twin B and twin A: /= 25% difference. The chi-square statistic was used to compare differences in the incidence of cesarean section between the groups. RESULTS: Total incidence of cesarean section was 266/927 (28.7%). Risk of delivering by a combined vaginal delivery and cesarean section was reduced if the presentation of twin B was vertex or breech (RR: 0.114; 95% confidence interval: 0.049-0.266) or if an epidural was used (RR: 0.380; 95% confidence interval: 0.163-0.883). In twin gestations eligible for vaginal delivery the risk of requiring delivery by cesarean section for both twins is reduced if the presentation of twin B was vertex (RR: 0.782; 95% confidence interval; 0.631-0.968), if an epidural was used (RR: 0.461; 95% confidence interval: 0.375-0.566), or if the birthweight discrepancy was <euro25% (RR: 0.695; 95% confidence interval: 0.524-0.922). CONCLUSION: Twin gestations with twin B presenting as vertex or breech or with an epidural were less likely to undergo combined vaginal delivery and cesarean section. The liberal use of epidural anesthesia may reduce the need for cesarean section in patients with twin gestations considered good candidates for vaginal delivery.

Anesthesia, Epidural↗
PubMed1983

Predicting and understanding mothers' infant-feeding intentions and behavior: testing the theory of reasoned action.

The present study examines the applicability of Fishbein and Ajzen's theory of reasoned action to the prediction and understanding of how primiparous and multiparous mothers intended to feed their infants and how they actually fed these infants during the 6 weeks following delivery. Measures of attitudes to behavior, subjective norms, and behavioral intentions were taken during the last trimester of pregnancy. Behavior was assessed by self-report 6 weeks postpartum. In most respects the findings supported the theory of reasoned action. However, attitudes to behavior were found to make an independent and significant contribution to the prediction of infant-feeding behavior, and the previous behavior of multiparous mothers explained an independent and significant proportion of variation in their behavioral intentions. The relative importance of the attitudinal and normative components of the theoretical model tended to vary according to whether the mothers had direct experience of the criterion behavior. Further analysis revealed that mothers who breast-fed during the 6-week postpartum period differed from those who bottle-fed exclusively during this period on a number of behavioral beliefs, outcome evaluations, and normative beliefs, and on one measure of motivation to comply. The implications of these findings for the theory of reasoned action are discussed.

Adolescent↗
PubMed2000

Plasticity in the maternal circuit: effects of experience and partum condition on brain astrocyte number in female rats.

Female rats that have received a maternal experience undergo enhanced c-fos expression in a number of brain sites when reexposed to pups. The present 2 studies examined changes in the expression of another brain protein, glial fibrillary acidic protein (GFAP), which is a major unit of the astrocytic cytoskeleton. In both experiments, primiparous and multiparous female rats were given varying amounts of postpartum contact with pups and overdosed after varying intervals, with no pups. Brains were prepared for GFAP immunohistochemical analysis. In both studies, Day 5 postpartum multiparous subjects given additional postpartum contact with pups, when compared with pup-exposed primiparous subjects, were found to have significantly higher numbers of GFAP positive cells in the medial preoptic area of the hypothalamus, an area critical for the expression of maternal behavior, but not in control sites. In Experiment 2, an opposite effect of parity was found in the medial amygdala and habenula.

Amygdala↗
PubMed2000

Women's and men's personal goals during the transition to parenthood.

To investigate how women's and men's personal goals change during the transition to parenthood, the authors studied 348 women (152 primiparous and 196 multiparous) and 277 of their partners at 3 times: early in pregnancy, 1 month before the birth, and 3 months afterward. At each measurement, participants completed the Personal Project Analysis questionnaire (B. R. Little, 1983). The results showed that during pregnancy women became more interested in goals related to childbirth, the child's health, and motherhood and less interested in achievement-related goals. After the birth women were more interested in family- and health-related issues. These changes were more substantial among the primiparous than among the multiparous mothers. Although the men's personal goals changed during the transition to parenthood, these changes were less substantial than those found among the women.

Adaptation, Psychological↗
PubMed1974

Differentiation between the embryonic and tumour specific antigens on chemically induced rat tumours.

The tumour specific antigens and tumour associated embryonic antigens expressed on chemically induced rat hepatomata and sarcomata have been shown to be different by means of blocking antibody studies. Serum from multiparous female rats contained blocking antibody which protected both tumour and embryo cells from the in vitro cytotoxic effect of lymph node cells from multiparous donors. These sera did not, however, block the cytotoxicity of lymph node cells from tumour immune rats for cells of the immunizing tumour. In addition, the tumour specific rejection antigens and embryonic antigens have been shown to have dissimilar locations in tumour cells.

Animals↗
PubMed2003

Oxytocin improves long-lasting spatial memory during motherhood through MAP kinase cascade.

Oxytocin is an essential hormone for mammalian labor and lactation. Here, we show a new function of oxytocin in causing plastic changes in hippocampal synapses during motherhood. In oxytocin-perfused hippocampal slices, one-train tetanus stimulation induced long-lasting, long-term potentiation (L-LTP) and phosphorylation of cyclic AMP-responsive element binding protein (CREB), and MAP kinase inhibitors blocked these inductions. An increase in CREB phosphorylation and L-LTP induced by one-train tetanus were observed in the multiparous mouse hippocampus without oxytocin application. Furthermore, intracerebroventricular injection of oxytocin in virgin mice improved long-term spatial learning in vivo, whereas an injection of oxytocin antagonist in multiparous mice significantly inhibited the improved spatial memory, L-LTP and CREB phosphorylation. These findings indicate that oxytocin is critically involved in improving hippocampus-dependent learning and memory during motherhood in mice.

Animals↗
PubMed2005

Reproductive factors and subtypes of breast cancer defined by hormone receptor and histology.

Reproductive factors are associated with reduced risk of breast cancer, but less is known about whether there is differential protection against subtypes of breast cancer. Assuming reproductive factors act through hormonal mechanisms they should protect predominantly against cancers expressing oestrogen (ER) and progesterone (PR) receptors. We examined the effect of reproductive factors on subgroups of tumours defined by hormone receptor status as well as histology using data from the NIHCD Women's Contraceptive and Reproductive Experiences (CARE) Study, a multicenter case-control study of breast cancer. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) as measures of relative risk using multivariate unconditional logistic regression methods. Multiparity and early age at first birth were associated with reduced relative risk of ER + PR + tumours (P for trend=0.0001 and 0.01, respectively), but not of ER - PR - tumours (P for trend=0.27 and 0.85), whereas duration of breastfeeding was associated with lower relative risk of both receptor-positive (P for trend=0.0002) and receptor-negative tumours (P=0.0004). Our results were consistent across subgroups of women based on age and ethnicity. We found few significant differences by histologic subtype, although the strongest protective effect of multiparity was seen for mixed ductolobular tumours. Our results indicate that parity and age at first birth are associated with reduced risk of receptor-positive tumours only, while lactation is associated with reduced risk of both receptor-positive and -negative tumours. This suggests that parity and lactation act through different mechanisms. This study also suggests that reproductive factors have similar protective effects on breast tumours of lobular and ductal origin.

Adult↗