Strain differences in parturition behavior and survival probability in rats (Rattus Norvegicus).

Three strains of laboratory rats (Wu:Cpb, CPB-B and WKY/Cpb) differing widely in reproductive success were compared concerning the role played by maternal behavior in the survival probability of pups. Parturition behavior of the dams was selected for study as pups are most dependent on the mother's behavior at, and immediately after birth. Great strain differences in survival rate of life born pups were found. However, differences between strains in parturition behavior were found to be restricted to only one pup oriented behavior and some non social behaviors. Besides no pups died at the day of birth nor did it seem probable that the strain differences we found in parturition behavior can be held responsible for the eventual death of pups during parturition. The suggestion is presented that strain differences in maternal behavior which affect survival chances of pups are to be looked for in the lactation period.     

Mortality after carotid body denervation in rats.

Carotid body denervation (CBD) in neonatal goats and piglets results in minimal irregular breathing and no fatalities. Redundancy and/or plasticity of peripheral chemosensitivity and a relatively mature ventilatory control system at birth may contribute to the paucity of CBD effects in these species. In the present study, we tested the hypothesis that CBD mortality would be greater in neonates of a less mature species such as the rat. We found that the mortality in rats denervated at 2-3 and 7-8 days of age was significantly higher (P < 0.05) than in sham-CBD rats. In all surviving rats, pulmonary ventilation during hypoxia was lower in CBD than in sham operated rats 2 days after denervation. In surviving rats denervated during the 7th and 8th postnatal days, there was also reduced weight gain and pulmonary ventilation during eupnea, including apneas up to 20 s in duration. However, the effects of CBD were compensated within 3 wk after denervation. Local injections of NaCN indicated that aortic chemoreceptors might have been one of the sites of recovery of peripheral chemosensitivity. We concluded that CBD has higher mortality in newborn rats than in other mammals, possibly because of the relative immaturity of these animals at birth. Nonetheless, in survivors there was enough redundancy and plasticity in the control of breathing to eventually compensate for the consequences of CBD.     

Strain differences in kidney copper concentrations of male rats

The copper concentrations of the kidneys of male rats of six inbred (BN, F344, LEW, SHR, WAG/Cpb, and WAG/Rij) and one random-bred Wistar strain were determined. In inbred rats the mean concentration varied between strains and ranged from 7.10 μg/g for F 344 to 23.48 μg/g for WAG/Cpb. The calculated coefficient of genetic determination (g²) was 0.88. A remarkable discrepancy was found between the two WAG inbred strains; the WAG/Cpb had a 2.5 times higher kidney Cu concentration than the WAG/Rij. Kidney Cu concentrations of random-bred rats varied considerably; the coefficient of variation of the means was 28 and 34% in two samples taken with a 1-yr interval, respectively, indicating inhomogeneity within the population. The results indicate that the individual differences in kidney Cu concentration have a genetic basis.     

Creeping: a new mutant rat with neurological disease

We describe a new mutant rat, named creeping, that exhibits severe ataxia characterized by a creeping posture due to the inability to stand up. Affected animals can be recognized at 14.8 +/- 1.6 (mean +/- SD) days of age and die within 35 days after birth. There are no sex differences in phenotype. The breeding data suggest that the abnormal locomotion is caused by an autosomal recessive gene. We have tentatively named the gene creeping (cre). The cerebellum of affected rats is much smaller than that of normal littermates. The cerebellar lobes of the mutant are barely formed. The notable histopathological changes are disarrangement of neuronal cells in the cerebellum and cerebral cortices, although the several cell types that are present in the cortices of normal rats are also found in the cortex of the creeping rats. The same type of change is also present in the hippocampus and fascia dentata.     

Clearance of apoptotic beta-cells is reduced in neonatal autoimmune diabetes-prone rats

The kinetics of beta-cell death in neonatal diabetes-prone (BBdp) and diabetes-resistant (BBdr) BioBreeding rats was investigated using both direct (histochemical) and indirect (mathematical modelling) techniques. In both BBdp and BBdr rats, the incidence of TUNEL positive beta-cells increased until 10 days of age before declining. The number of apoptotic beta-cells was significantly higher in BBdp as compared to BBdr neonates from birth until 20 days of age (P<0.05). Using a mathematical model applied to the time course of beta-cell mass and replication rate, a wave of net beta-cell loss was detected between 10 and 20 days of age in both strains. In contrast to the observed difference in the incidence of TUNEL positive beta-cells, with the model-based approach we found no difference in the rate of beta-cell apoptosis between BBdp and BBdr rats prior to weaning. As the number of apoptotic cells present in a tissue depends on the rate at which cells die and the rate at which the apoptotic cell debris is cleared, we compared in vitro phagocytosis of apoptotic thymocytes by peritoneal macrophages from 2-week-old BBdp and BBdr rats. Macrophages from BBdp neonates engulfed significantly less apoptotic cells as compared to BBdr neonates (P<0.0005). Taken together, these findings suggest that there is impaired clearance of apoptotic beta-cells in diabetes-prone BB rats during the neonatal period.     

The use of a rat-derived microflora for providing colonization resistance in SPF rats

To obtain a suitable species-specific microflora for a new rat SPF-unit, germ-free WAG/Rij rats were associated with a flora derived originally from selectively decontaminated Cpb: WU (Wistar) rats. Caecal and ileal contents of these rats had been cultured anaerobically (37 degrees C) for 7 days and harvested. This cultured flora was given to germ-free Cpb: SE (Swiss) mice, which were kept in an isolator system and acted as a source of the flora to associate germ-free Wag/Rij rats. In these associated rats, several parameters indicative of the 'quality' of the intestinal microflora were investigated and compared to those in rats with a mouse derived anaerobic microflora. Parameters included relative caecal weight, colonization resistance and the concentration of faecal bile acids. The cultured rat-derived microflora normalized the observed intestinal parameters better than the mouse derived microflora, and provided better colonization resistance. We conclude that culturing of intestinal contents of selectively decontaminated animals can be a useful way to obtain a species-specific donor-microflora which can be used to start new SPF units.     

Effects of prenatal perfluorooctane sulfonate (PFOS) exposure on lung maturation in the perinatal rat

BACKGROUND: Perfluorooctane sulfonate (PFOS), found widely in wildlife and humans, is environmentally and metabolically stable. Environmental PFOS may be from its use as a surfactant, hydrolysis of perfluorooctanesulfonyl fluoride, and degradation of N-alkyl-perfluorooctanesulfonamide compounds formerly used in numerous applications. Prenatal exposure to PFOS in rodents causes neonatal mortality; treatment on gestation days (GD) 19-20 is sufficient to induce neonatal death in rats. Affected pups are born alive but present with labored breathing. Their lungs are pale and often do not expand fully on perfusion. METHODS: Pregnant Sprague-Dawley rats received 0, 25, or 50 mg/kg/day PFOS/K+ orally on GD 19-20. Lungs from GD 21 fetuses and neonates were prepared for histology and morphometry. Rescue experiments included co-administration of dexamethasone or retinyl palmitate with PFOS. Pulmonary surfactant was investigated with mass spectrometry in GD 21 amniotic fluid and neonatal lungs. Microarray analysis was carried out on PND 0 lungs. RESULTS: Histologically, alveolar walls were thicker in lungs of PFOS-exposed newborns compared to controls. The ratio of solid tissue:small airway was increased, suggesting immaturity. Rescue studies were ineffective. Phospholipid concentrations and molecular speciation were unaffected by PFOS. No changes in markers of alveolar differentiation were detected by microarray analysis. CONCLUSIONS: Morphometric changes in lungs of PFOS exposed neonates were suggestive of immaturity, but the failure of rescue agents and normal pulmonary surfactant profile indicate that the labored respiration and mortality observed in PFOS-treated neonates was not due to lung immaturity.     

Developmental studies on gamma-glutamyl transferase in rat intestinal mucosa.

The activity of gamma-GT in rat intestinal mucosa has been studied during normal development. No significant differences in enzymatic activity have been recorded between 21-day-old fetuses, neonates tested at 3, 10, 20 and 30 days and older animals (65 days). Only in the period immediately prior to birth did the liver gamma-GT display activity levels similar to those of intestinal gamma-GT. In neonates and in adult rats, the intestinal gamma-GT activity was much higher as compared to the enzymatic activity in the liver, possibly revealing a species feature in rats. The results of the studies show that the rat is particularly suitable for experimental studies on intestinal gamma-GT in pathological conditions.     

Maternal reproductive experience enhances early postnatal outcome following gestation and birth of rats in hypergravity

A major goal of space life sciences research is to broaden scientific knowledge of the influence of gravity on living systems. Recent spaceflight and centrifugation studies demonstrate that reproduction and ontogenesis in mammals are amenable to study under gravitational conditions that deviate considerably from those typically experienced on Earth (1 x g). In the present study, we tested the hypothesis that maternal reproductive experience determines neonatal outcome following gestation and birth under increased (hyper) gravity. Primigravid and bigravid female rats and their offspring were exposed to 1.5 x g centrifugation from Gestational Day 11 either through birth or through the first postnatal week. On the day of birth, litter sizes were identical across gravity and parity conditions, although significantly fewer live neonates were observed among hypergravity-reared litters born to primigravid dams than among those born to bigravid dams (82% and 94%, respectively; 1.0 x g controls, 99%). Within the hypergravity groups, neonatal mortality was comparable across parity conditions from Postnatal Day 1 through Day 7, at which time litter sizes stabilized. Maternal reproductive experience ameliorated neonatal losses during the first 24 h after birth but not on subsequent days, and neonatal mortality was associated with changes in maternal care patterns. These results indicate that repeated maternal reproductive experience affords protection against neonatal losses during exposure to increased gravity. Differential mortality of neonates born to primigravid versus bigravid dams denotes gravitational load as one environmental mechanism enabling the expression of parity-related variations in birth outcome.     

High Incidence of Neonatal Danger Signs and Its Implications for Postnatal Care in Ghana: A Cross-Sectional Study

Background

Reducing neonatal mortality is a major public health priority in sub-Saharan Africa. Numerous studies have examined the determinants of neonatal mortality, but few have explored neonatal danger signs which potentially cause morbidity. This study assessed danger signs observed in neonates at birth, determined the correlations of multiple danger signs and complications between neonates and their mothers, and identified factors associated with neonatal danger signs.

Methods

A cross-sectional study was conducted in three sites across Ghana between July and September in 2013. Using two-stage random sampling, we recruited 1,500 pairs of neonates and their mothers who had given birth within the preceding two years. We collected data on their socio-demographic characteristics, utilization of maternal and neonatal health services, and experiences with neonatal danger signs and maternal complications. We calculated the correlations of multiple danger signs and complications between neonates and their mothers, and performed multiple logistic regression analysis to identify factors associated with neonatal danger signs.

Results

More than 25% of the neonates were born with danger signs. At-birth danger signs in neonates were correlated with maternal delivery complications (r = 0.20, p < 0.001), and neonatal complications within the first six weeks of life (r = 0.19, p < 0.001). However, only 29.1% of neonates with danger signs received postnatal care in the first two days, and 52.4% at two weeks of life. In addition to maternal complications during delivery, maternal age less than 20 years, maternal education level lower than secondary school, and fewer than four antenatal care visits significantly predicted neonatal danger signs.

Conclusions

Over a quarter of neonates are born with danger signs. Maternal factors can be used to predict neonatal health condition at birth. Management of maternal health and close medical attention to high-risk neonates are crucial to reduce neonatal morbidity in Ghana.     

Rapid karyotyping of neonates on the basis of data from cord blood.

A method is described for karyotyping neonates on the basis of data from cord blood--by means of direct examination of dividing cells--that yields results within a few hours of birth. This method obviates the need for bone-marrow aspiration when chromosome studies are required urgently.     

Abnormal bile acid pool and composition in neonates of spontaneously diabetic Wistar BB rats and its change during development

Streptozotocin-induced diabetes during pregnancy in rats causes a decrease in primary bile acid pool in neonates. To rule out direct drug effect on the fetus as the basis for this change, studies of bile acid pool and composition at birth and during subsequent development was carried out in neonates of spontaneously diabetic Wistar BB rats and compared to control neonates. The cholic acid pool in neonates of diabetic rats was lower when compared to control neonates at birth. The pool of secondary bile acids was markedly increased in neonates of diabetic rats, with increases in lithocholic and 3 beta,12 alpha-dihydroxycholanoic acid. With age, the cholic acid pool of neonates from diabetic rats was increased and at 3 months of age it was actually higher than in control neonates. The pool of chenodeoxycholic at diabetes onset age was lower in neonates of diabetic rats. HDL-cholesterol was lower in neonates of diabetic rats at 1 week, but this reversed at 3 months of age. These studies firmly establish that neonates of diabetic rats have abnormal bile acid pool and composition at birth which changes to adult diabetic pattern with age.     

Neonatal weight in gibbons (Hylobates spp.)

Neonatal and birth weights of gibbons have mostly been reported for single individuals, and larger samples (n = 2–8) have apparently been published for only two species of gibbons (Hylobates lar and H. syndactylus). In addition, a critical examination of the few published neonatal weights of gibbons shows that several of them should not be used. Neonatal weights are here defined as weights taken on infants up to seven days old, whereas birth weights include only those taken on the day of birth. This paper presents neonatal weights for six representative species of gibbons (H. lar, H. leucogenys, H. moloch, H. muelleri, H. pileatus, H. syndactylus) and some of their hybrids. Most of our data stem from surviving animals that were subsequently hand-reared and include 80 infants, thus making the previously available dataset 5 times larger. Our neonatal weights fall roughly into three different classes: neonates of the lar group (about 390 g, n = 27), the concolor group (about 510 g, n = 7), and the siamang (about 540 g, n = 46). This grouping corresponds not only to taxonomic units within the hylobatids, but also to grouping of gibbons by adult body weight. No weight difference between males and females is evident in our sample, and hybrids of the lar group do not appear to differ in weight from pure species. True birth weights (i.e., weights recorded on the day of birth) are available for only a few individuals. These weights are, on average, 7% higher than neonatal weights, but the difference is not statistically significant. Additional samples of neonatal weights suggest that infants that die on the day of birth weigh, on average, 17% less, twins weigh 29% less, and infants born by Cesarean section weigh 19% more than our reference sample of neonates. © 1995 Wiley-Liss, Inc.     

Ontogenic changes in metabolism and transport of glutathione in the rat

Changes in the level of glutathione (GSH), the turnover rate, and gamma-glutamyltransferase (GGT) activity were examined in newborn, weanling, and adult male Wistar rats, the objective being to elucidate the mechanisms which control the hepatic GSH level during maturation as well as under conditions of different degrees of protein ingestion. The hepatic GGT activity in the newborn rats was high at birth, decreased within a few days to 1 to 2% of the initial level, and remained unchanged thereafter, when these rats were fed a normal diet after 3 weeks of age. In contrast, the hepatic GSH level increased 3-4-fold while total GGT activity in the kidney increased 6-8-fold. When weanling rats were fed a low protein diet (containing 10% soy protein) for 3 weeks, the hepatic GSH level decreased markedly while the GGT activity increased 5-6-fold. The turnover rate of hepatic GSH also increased, as determined by the use of buthionine sulfoximine, a specific inhibitor of GSH synthesis; a value of 2.1 h was obtained in comparison with 3.5 h for that of rats fed the normal laboratory chow (CRF-1). On the other hand, feeding adult rats on the low protein diet resulted in a marked decrease in hepatic GSH level with no effect on either hepatic or renal GGT activity. These results together with other observations may suggest that GSH translocated out of liver cells in the newborn rats is degraded mainly by these cells, while the tripeptide secreted by hepatocytes of adult rats is metabolized predominantly in extrahepatic tissues, such as the kidney.(ABSTRACT TRUNCATED AT 250 WORDS)     

Birth spacing patterns in humans and apes

Comparative studies of birth interval dynamics in wild primates suffer from several problems of analysis and interpretation: (1) the data are always right-censored, (2) sample sizes are usually small, (3) the distribution of birth intervals is expected to be non-normal, (4) early offspring mortality is a confounding variable, and (5) differences in life history (e.g., presence or absence of menopause) can complicate interpretation of the results. A survival analysis designed to minimize these problems is applied to published data on wild chimpanzees and gorillas from Gombe and Virunga Parks, respectively, and to new data on wild orangutans from Tanjung Puting National Park and on a human population, the Gainj of highland Papua New Guinea. According to this analysis, the estimated median birth interval (when the offspring whose birth opens the interval does not die within the interval) is 43.3 +/- 1.0 months for the Gainj, 45.5 +/- 1.2 months for gorillas, 66.6 +/- 1.3 months for chimpanzees, and 92.6 +/- 2.4 months for orangutans.     

Effects of aminoglutethimide phosphate on litter size and birth weight in superovulated rats

In this study, litter sizes, birth weights and survival rates of neonates in superovulated rats treated with aminoglutethimide phosphate (AGP) were studied. Young (8- to 9-week old) and adult (14- to 16-week old) rats were treated with 20 or 40 IU PMSG between 1100 and 1300 hours on the day of early diestrus, followed by identical doses of hCG 52 to 54 hours later. These rats received 10 mg AGP on Days 0 to 2 of pregnancy (AGP rats). The duration of pregnancy in the AGP-treated and control rats was about the same. Mean live litter sizes in young and in adult AGP rats treated with 20 IU PMSG and 20 IU hCG were significantly higher (15.5 and 15.4; P<0.01) than in the control rats (11.5 and 12.6). When AGP was given to young and adult rats pretreated with 40 IU PMSG and 40 IU hCG, they produced means of 17.7 and 17.3 live neonates, respectively. The birth weights for young (5.55 to 5.88 g) and adult (5.89 to 5.96 g) AGP rats were smaller than those of respective control rats (6.44 and 6.40 g; P < 0.05-0.01). When the number of neonates was adjusted to 8 per dam for nursing and rearing, all of them were alive at 5 weeks after birth and showed normal growth. However, body weight gains of the progeny of AGP dams were lower than those of controls. These results indicate that rats treated with large doses of gonadotropins and AGP produce larger litter sizes than nontreated controls.     

Early identification of neonates at risk: traits of newborn piglets with respect to survival

Despite technological changes and improved management, piglet mortality remains a problem for both production and welfare. Most preweaning mortality occurs within the first 3 days after birth because of problems with adaptation and development. Thus, the purpose of our study was to determine the physiologic state of newborn pigs with respect to piglet survival. Data were collected from 1024 live-born piglets of 106 primiparous German Landrace sows to analyze relationships between farrowing traits, early postnatal vitality and blood chemistry, including immunity of piglets at birth. Surviving piglets were compared with those that died during the first 10 days of life. The survivors were significantly heavier at birth (P=0.001), were born earlier in the birth order (P=0.04), reached the udder and took in first colostral milk more quickly (P=0.001) and had a smaller drop in rectal temperature I h after birth (P=0.001) than dead. However, dead piglets had significantly higher blood levels of inorganic phosphorus (P=0.0001), calcium (P=0.04) and urea (P=0.05), but a lower concentration of alpha2-macroglobulin and lower lymphocyte proliferation indices in response to pokeweed mitogen (P=0.05). Models fitted for discrimination between survivors and piglets that died included, in addition to birth weight and litter size, the foraging behavior of neonates (time from birth to first suckle) and their thermoregulatory capacity (rectal temperature 1 h after birth) in the first experimental unit, as well as prenursing biochemical measures (inorganic phosphorus, calcium and glucose) in the second experimental unit. These ethophysiological and biochemical traits of early postnatal vitality are important determinants of maturity and development at birth. Hence, breeding programs and perinatal housing and feeding conditions should ensure a high physiological maturity to improve mortality rates of neonates.     

Do Biological and Bedsite Characteristics Influence Survival of Neonatal White-Tailed Deer?

Coyotes recently expanded into the eastern U.S. and potentially have caused localized white-tailed deer population declines. Research has focused on quantifying coyote predation on neonates, but little research has addressed the potential influence of bedsite characteristics on survival. In 2011 and 2012, we radiocollared 65 neonates, monitored them intensively for 16 weeks, and assigned mortality causes. We used Program MARK to estimate survival to 16 weeks and included biological covariates (i.e., sex, sibling status [whether or not it had a sibling], birth weight, and Julian date of birth). Survival to 16 weeks was 0.141 (95% CI = 0.075-0.249) and the top model included only sibling status, which indicated survival was lower for neonates that had a sibling. Predation was the leading cause of mortality (35 of 55; 64%) and coyotes were responsible for the majority of depredations (30 of 35; 86%). Additionally, we relocated neonates for the first 10 days of life and measured distance to firebreak, visual obstruction, and plant diversity at bedsites. Survival of predation to 10 days (0.726; 95% CI = 0.586-0.833) was weakly associated with plant diversity at bedsites but not related to visual obstruction. Our results indicate that neonate survival was low and coyote predation was an important source of mortality, which corroborates several recent studies from the region. Additionally, we detected only weak support for bedsite cover as a covariate to neonate survival, which indicates that mitigating effects of coyote predation on neonates may be more complicated than simply managing for increased hiding cover.     

Maternal supplementation with dietary arachidonic and docosahexaenoic acids during lactation elevates bone mass in weanling rat and guinea pig offspring even if born small sized

Whether post-natal long chain polyunsaturated fatty acids (LCPUFA) elevates bone mineral content (BMC) of small and normal neonates was studied using pregnant rats and guinea pigs fed a control (C) diet or low protein (LP) diet to induce small neonates followed by C or LCPUFA diets during lactation. Measurements (days 3 and 21 post-partum) included BMC and density (BMD) plus bone metabolism. In rats LP reduced birth weight but at day 21 elevated weight and whole body BMC; LCPUFA enhanced spine BMC, tibia BMC and BMD and whole body BMD. In guinea pig pups, at days 3 and 21, LP reduced weight, whole body and regional BMC and BMD whereas LCPUFA reduced day 3 osteocalcin and elevated day 21 spine BMD. LCPUFA minimized loss of whole body BMC in dams and elevated osteocalcin in sows. LCPUFA during lactation enhances bone in normal and small neonates without compromising maternal bone.