Human Infants (human + infant)

Distribution by Scientific Domains

Selected Abstracts

Commentary: An Early, Short, and Useful Sensitive Period in the Human Infant

BIRTH, Issue 2 2009
Marshall H. Klaus MD
No abstract is available for this article. [source]

Discrimination of Large and Small Numerosities by Human Infants

INFANCY, Issue 3 2004
Jennifer S. Lipton
Six experiments investigated infants' sensitivity to numerosity in auditory sequences. In prior studies (Lipton & Spelke, 2003), 6-month-old infants discriminated sequences of 8 versus 16 but not 8 versus 12 sounds, and 9-month-old infants discriminated 8 versus 12 but not 8 versus 10 sounds, when the continuous variables of rate, sound duration, and sequence duration were controlled. The current studies investigated whether infants' numerical discrimination is subject to the signature ratio limit of adults' numerosity discrimination. Four experiments at 6 and 9 months provided evidence for this signature limit, suggesting that common mechanisms underlie numerosity discrimination in infants and adults. In further experiments, infants failed to discriminate 2 versus 4 or 2 versus 3 sounds when tested under the same conditions as with large numbers. These findings accord with studies using visual-spatial arrays (e.g., Clearfield & Mix, 1999) and suggest that separate systems underlie infants' representation of small and large numerosities. [source]

Pointing Behaviors in Apes and Human Infants: A Balanced Interpretation

Juan-Carlos Gómez
This article presents a tentatively "balanced" view (i.e., midway between lean and rich interpretations) of pointing behavior in infants and apes, based upon the notion of intentional reading of behavior without simultaneous attribution of unobservable mental states. This can account for the complexity of infant pointing without attributing multilayered mindreading to infants. It can also account for ape pointing, which shares some of the complexities of infant pointing, but departs from it in other respects, notably in its range of motives and its focus upon the regulation of executive behavior. The article explores some explanations for these similarities and differences and calls for a new look at human infant communication unbiased by adult communication models. [source]

Perceptual Completion in Newborn Human Infants

Eloisa Valenza
Despite decades of studies of human infants, a still open question concerns the role of visual experience in the development of the ability to perceive complete shapes over partial occlusion. Previous studies show that newborns fail to manifest this ability, either because they lack the visual experience required for perceptual completion or because they fail to detect the pattern of motion. To distinguish these possibilities, newborns' perception of a center-occluded object was tested, using stroboscopic motion. Infants (mean age of 72 hr) perceived the object as a connected unit, providing the first evidence that the newborn is capable of filling in gaps in the visible surface layout when the relevant visual information can be detected by his or her immature visual system. [source]

Regional Fos expression induced by morphine withdrawal in the 7-day-old rat

Anika A. McPhie
Abstract Human infants are often exposed to opiates chronically but the mechanisms by which opiates induce dependence in the infant are not well studied. In the adult the brain regions involved in the physical signs of opiate withdrawal include the periaqueductal gray area, the locus coeruleus, amygdala, ventral tegmental area, nucleus accumbens, hypothalamus, and spinal cord. Microinjection studies show that many of these brain regions are involved in opiate withdrawal in the infant rat. Our goal here was to determine if these regions become metabolically active during physical withdrawal from morphine in the infant rat as they do in the adult. Following chronic morphine or saline treatment, withdrawal was precipitated in 7-day-old pups with the opiate antagonist naltrexone. Cells positive for Fos-like immunoreactivity were quantified within select brain regions. Increased Fos-like labeled cells were found in the periaqueductal gray, nucleus accumbens, locus coeruleus, and spinal cord. These are consistent with other studies showing that the neural circuits underlying the physical signs of opiate withdrawal are similar in the infant and adult. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 544,552, 2009. [source]

Enculturated chimpanzees imitate rationally

David Buttelmann
Human infants imitate others' actions ,rationally': they copy a demonstrator's action when that action is freely chosen, but less when it is forced by some constraint (Gergely, Bekkering & Király, 2002). We investigated whether enculturated chimpanzees (Pan troglodytes) also imitate rationally. Using Gergely and colleagues' (2002) basic procedure, a human demonstrator operated each of six apparatuses using an unusual body part (he pressed it with his forehead or foot, or sat on it). In the Hands Free condition he used this unusual means even though his hands were free, suggesting a free choice. In the Hands Occupied condition he used the unusual means only because his hands were occupied, suggesting a constrained or forced choice. Like human infants, chimpanzees imitated the modeled action more often in the Hands Free than in the Hands Occupied condition. Enculturated chimpanzees thus have some understanding of the rationality of others' intentional actions, and use this understanding when imitating others. [source]

Unique Susceptibility of the Fetal Thymus to Feline Immunodeficiency Virus Infection: An Animal Model for HIV Infection In Utero1

PROBLEM: Human infants infected in utero with HIV develop thymus insufficiency and progress to AIDS sooner than infants infected peripartum. However, direct analysis of the thymus is difficult due to limited tissue access and variable timing of vertical transmission. METHOD OF STUDY: Fetal and neonatal cats were inoculated with feline immunodeficiency virus (FIV) at an equivalent infectious dose. The thymus, blood, and lymph nodes were harvested and compared at 23 and 46 days post-inoculation (p.i.) and also compared to sham-inoculated, age-matched controls. Lymphocyte phenotypes were analyzed by flow cytometry and virus burden was quantified in histologic sections and by virus isolation from plasma. RESULTS: Fetal cats inoculated with FIV had acute thymus atrophy at birth, which coincided with peak viremia. At 46 days p.i., thymus size and cell composition rebounded and supported increased productive infection. In contrast, neonatal cats inoculated with FIV developed chronic thymus atrophy and degeneration, which was associated with decreasing productive infection and low-level viremia. CONCLUSIONS: The fetal thymus is uniquely vulnerable to acute, transient depletion and high-level productive infection. The neonatal thymus is less vulnerable to acute changes, and responds through progressive atrophy and declining productive infection. Reduced immune competence, as reflected by the failure to control virus replication, may contribute to the accelerated progression of FIV and HIV infections in utero. [source]

Aspects of Infant Food Formulation

D.K. Thompkinson
ABSTRACT:, Milk is a biological fluid of exceptional complexity. It contains the nutrients for the growth and development of the newborn. The compositional structure of milk is, however, dependent on the species and tailored to sustain growth and development of its own offspring. Human milk contains specific proteins, lipids, and other components designed to be easily digestible and which have important roles to play in child development. Human infants should ideally be nursed on mother's milk, which constitutes nature's best food. However, in the event of lactation failure, insufficient milk secretion, and where mothers are suffering from transmittable diseases, human milk substitutes serve as savers of precious life during vulnerable stages of infancy. Bovine milk as such or with certain modifications has been widely used for infant feeding. There has been an ever-increasing reliance on formula feeding practices both in developed and developing countries. Bovine milk based dried formulations have become a prominent feature of infantile dietetics. Emphasis has been laid on the manufacture of formulations having compositional and biochemical characteristics similar to human milk. The technological advancement for the production of infant formula has come a long way in the manufacture of a variety of infant formulae for the dietary management of infants. This is a comprehensive review providing insight on the detailed compositional differences of various nutrients present in human milk as compared to bovine milk, their makeup, significance, and recommended levels of intake that are best suited for the growth and development of infants fed on modified/prepared infant formulations. [source]

Spontaneous kicking in full-term and preterm infants with and without white matter disorder

Linda Fetters
Abstract Early damage to white matter of the brain may have developmental consequences for prematurely born infants including the coordination of leg movements. Our perspective is that white matter damage initiates an ontogenetic course that may lead to movement dysfunction leading to disability. In this study, spontaneous kicking in the human infant is a "window" for evaluating the potential consequences of perinatal brain damage for sensori-motor coordination. We compare the intra-limb coordination patterns of 5-month-old premature infants with white matter damage (PTWMD) to a group of prematurely born infants without WMD (PT) and a group of full-term (FT) infants. The PT group demonstrates advanced kicking patterns in comparison to both the PTWMD and FT groups. The PTWMD group has less mature patterns than the FT group on some, but not all measures. The movement challenge for PTWMD infants may be in the transition from spontaneous kicking to movements with the legs that require decoupling of intralimb joints. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52: 524,536, 2010. [source]

Perception of audiovisual rhythm and its invariance in 4- to 10-month-old infants

David J. Lewkowicz
Abstract This study investigated the perception of complex audiovisual rhythmic patterns in 4-, 6-, 8-, and 10-month-old human infants. In Experiment 1, we first habituated infants to an event in which an object could be seen and heard bouncing in a rhythmic fashion. We then tested them to determine if they would detect a relative temporal pattern change produced by rearranging the intrapattern intervals. Regardless of age, infants successfully detected the pattern change. In Experiment 2, we asked whether infants also can extract rhythmic pattern invariance amid tempo variations. Thus, we first habituated infants to a particular rhythmic pattern but this time varying in its tempo of presentation across trials. We then administered one test trial in which a novel rhythm was presented at a familiar tempo and another test trial in which a familiar rhythm was presented at a novel tempo. Infants detected both types of changes indicating that they perceived the invariant rhythm and that they did so despite the fact that they also detected the varying tempo. Overall, the findings demonstrate that infants between 4 and 10 months of age can perceive and discriminate complex audiovisual temporal patterns on the basis of relative temporal differences and that they also can learn the invariant nature of such patterns. © 2006 Wiley Periodicals, Inc. Dev Psyshobiol 48: 288,300, 2006. [source]

Maternal exposure to first-trimester sunshine is associated with increased birth weight in human infants

Karen Tustin
Abstract Two alternative hypotheses have been generated to account for seasonal variation in the birth weight of human infants born in industrialized countries. First, it has been hypothesized that low ambient temperature during the second trimester of gestation decreases birth weight. Second, it has been hypothesized that exposure to bright sunshine during the first trimester increases birth weight. We tested these two hypotheses to determine which, if either, accounted for seasonal variation in birth weight of full-term infants. Birth weight data, collected over a 5-year period, were analyzed as a function of peak and trough sunshine and ambient temperature. Although there was no effect of ambient temperature during any trimester on birth weight, infants whose mothers were exposed to peak sunshine during their first trimester were born significantly heavier than infants whose mothers experienced trough levels of sunshine during the same trimester. Furthermore, infants whose mothers were exposed to trough levels of sunshine during their second and third trimesters were born significantly heavier than infants whose mothers were exposed to peak levels of sunshine during the same trimesters. We hypothesize that high levels of sunshine during early gestation may increase the level of insulin-like growth factor (IGF)-1, facilitating prenatal growth. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 45: 221,230, 2004. [source]

Correlated attributes and categorization in the first half-year of life

Ramesh S. Bhatt
Abstract In two experiments with 36 human infants, we asked whether 3- and 6-month-olds could use correlations between attributes of individual objects to categorize. Infants learned to kick to move block mobiles that simultaneously displayed two categories defined by the figures displayed on them: the colors of the figures and the colors of the blocks. Two features were correlated, and the third varied across categories. Only 6-month-olds categorized novel category exemplars that preserved the original feature correlations (Experiment 1A), but both 3- and 6-month-olds discriminated feature recombinations that broke the original correlations (Experiment 1B). When category exemplars were presented successively, 6-month-olds also learned the feature correlations and used them to categorize (Experiment 2), but their performance was less robust. Infants' superior learning when stimuli were presented simultaneously may reflect "unitization," a learning disposition unique to immature infants. These experiments reveal that infants' ability to use correlated attributes to categorize emerges months earlier than previously thought. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 44: 103,115, 2004. [source]

Effects of redundant and nonredundant bimodal sensory stimulation on heart rate in bobwhite quail embryos

Greg D. Reynolds
Abstract Research with both animal embryos and human infants has provided evidence that information presented redundantly and in temporal synchrony across sensory modalities (intersensory redundancy) can guide selective attention, perceptual learning, and memory during early development. How this facilitation is achieved remains relatively unexamined. This study examined the effects of redundant versus nonredundant bimodal stimulation on a measure of physiological arousal (heart rate) in bobwhite quail embryos. Results show that quail embryos exposed to concurrent but nonredundant auditory and visual stimulation during the late stages of incubation exhibit significantly elevated heart rates following stimulus exposure and during stimulus reexposure when compared to embryos exposed to redundant and synchronous audiovisual stimulation, unimodal auditory stimulation, or no supplemental prenatal sensory stimulation. These findings indicate a functional distinction between redundant and nonredundant bimodal stimulation during early development and suggest that nonredundant bimodal stimulation during the prenatal period can raise arousal levels, thereby potentially interfering with the attentional capacities and perceptual learning of bobwhite quail. In contrast, intersensory redundancy appears to foster arousal levels that facilitate selective attention and perceptual learning during prenatal development. © 2003 Wiley Periodicals, Inc. Dev Psychobiol 43: 304,310, 2003. [source]

Testing neural models of the development of infant visual attention

John E. Richards
Abstract Several models of the development of infant visual attention have used information about neural development. Most of these models have been based on nonhuman animal studies and have relied on indirect measures of neural development in human infants. This article discusses methods for studying a "neurodevelopmental" model of infant visual attention using indirect and direct measures of cortical activity. We concentrate on the effect of attention on eye movement control and show how animal-based models, indirect measurement in human infants, and direct measurement of brain activity inform this model. © 2002 Wiley Periodicals, Inc. Dev Psychobiol 40: 226,236, 2002. DOI 10.1002/dev.10029 [source]

Sensitivity to communicative relevance tells young children what to imitate

Victoria Southgate
How do children decide which elements of an action demonstration are important to reproduce in the context of an imitation game? We tested whether selective imitation of a demonstrator's actions may be based on the same search for relevance that drives adult interpretation of ostensive communication. Three groups of 18-month-old infants were shown a toy animal either hopping or sliding (action style) into a toy house (action outcome), but the communicative relevance of the action style differed depending on the group. For the no prior information group, all the information in the demonstration was new and so equally relevant. However, for infants in the ostensive prior information group, the potential action outcome was already communicated to the infant prior to the main demonstration, rendering the action style more relevant. Infants in the ostensive prior information group imitated the action style significantly more than infants in the no prior information group, suggesting that the relevance manipulation modulated their interpretation of the action demonstration. A further condition (non-ostensive prior information) confirmed that this sensitivity to new information is only present when the ,old' information had been communicated, and not when infants discovered this information for themselves. These results indicate that, like adults, human infants expect communication to contain relevant content, and imitate action elements that, relative to their current knowledge state or to the common ground with the demonstrator, is identified as most relevant. [source]

Enculturated chimpanzees imitate rationally

David Buttelmann
Human infants imitate others' actions ,rationally': they copy a demonstrator's action when that action is freely chosen, but less when it is forced by some constraint (Gergely, Bekkering & Király, 2002). We investigated whether enculturated chimpanzees (Pan troglodytes) also imitate rationally. Using Gergely and colleagues' (2002) basic procedure, a human demonstrator operated each of six apparatuses using an unusual body part (he pressed it with his forehead or foot, or sat on it). In the Hands Free condition he used this unusual means even though his hands were free, suggesting a free choice. In the Hands Occupied condition he used the unusual means only because his hands were occupied, suggesting a constrained or forced choice. Like human infants, chimpanzees imitated the modeled action more often in the Hands Free than in the Hands Occupied condition. Enculturated chimpanzees thus have some understanding of the rationality of others' intentional actions, and use this understanding when imitating others. [source]

Listening to language at birth: evidence for a bias for speech in neonates

Athena Vouloumanos
The nature and origin of the human capacity for acquiring language is not yet fully understood. Here we uncover early roots of this capacity by demonstrating that humans are born with a preference for listening to speech. Human neonates adjusted their high amplitude sucking to preferentially listen to speech, compared with complex non-speech analogues that controlled for critical spectral and temporal parameters of speech. These results support the hypothesis that human infants begin language acquisition with a bias for listening to speech. The implications of these results for language and communication development are discussed. [source]

Number sense in human infants

Fei Xu
Four experiments used a preferential looking method to investigate 6-month-old infants' capacity to represent numerosity in visual-spatial displays. Building on previous findings that such infants discriminate between arrays of eight versus 16 discs, but not eight versus 12 discs (Xu & Spelke, 2000), Experiments 1 and 2 investigated whether infants' numerosity discrimination depends on the ratio of the two set sizes with even larger numerosities. Infants successfully discriminated between arrays of 16 versus 32 discs, but not 16 versus 24 discs, providing evidence that their discrimination shows the set-size ratio signature of numerosity discrimination in human adults, children and many non-human animals. Experiments 3 and 4 addressed a controversy concerning infants' ability to discriminate large numerosities (observed under conditions that control for total filled area, array size and density, item size and correlated properties such as brightness: Brannon, 2002; Xu, 2003b; Xu & Spelke, 2000) versus small numerosities (not observed under conditions that control for total contour length: Clearfield & Mix, 1999). To investigate the sources of these differing findings, Experiment 3 tested infants' large-number discrimination with controls for contour length, and Experiment 4 tested small-number discrimination with controls for total filled area. Infants successfully discriminated the large-number displays but showed no evidence of discriminating the small-number displays. These findings provide evidence that infants have robust abilities to represent large numerosities. In contrast, infants may fail to represent small numerosities in visual-spatial arrays with continuous quantity controls, consistent with the thesis that separate systems serve to represent large versus small numerosities. [source]

Sound induces perceptual reorganization of an ambiguous motion display in human infants

Christian Scheier
Adults who watch an ambiguous visual event consisting of two identical objects moving toward, through, and away from each other and hear a brief sound when the objects overlap report seeing visual bouncing. We conducted three experiments in which we used the habituation/test method to determine whether these illusory effects might emerge early in development. In Experiments 1 and 3 we tested 4-, 6- and 8-month-old infants' discrimination between an ambiguous visual display presented together with a sound synchronized with the objects' spatial coincidence and the identical visual display presented together with a sound no longer synchronized with coincidence. Consistent with illusory perception, the 6- and 8-month-old, but not the 4-month-old, infants responded to these events as different. In Experiment 2 infants were habituated to the ambiguous visual display together with a sound synchronized with the objects' coincidence and tested with a physically bouncing object accompanied by the sound at the bounce. Consistent with illusory perception again, infants treated these two events as equivalent by not exhibiting response recovery. The developmental emergence of this intersensory illusion at 6 months of age is hypothesized to reflect developmental changes in object knowledge and attentional mechanisms. [source]

Learning to perceive object unity: a connectionist account

Denis Mareschal
To explore questions of how human infants begin to perceive partly occluded objects, we devised two connectionist models of perceptual development. The models were endowed with an existing ability to detect several kinds of visual information that have been found important in infants' and adults' perception of object unity (motion, co-motion, common motion, relatability, parallelism, texture and T-junctions). They were then presented with stimuli consisting of either one or two objects and an occluding screen. The models' task was to determine whether the object or objects were joined when such a percept was ambiguous, after specified amounts of training with events in which a subset of possible visual information was provided. The model that was trained in an enriched environment achieved superior levels of performance and was able to generalize veridical percepts to a wide range of novel stimuli. Implications for perceptual development in humans, current theories of development and origins of knowledge are discussed. [source]

Searching for food in the wild: a nonhuman rimate's expectations about invisible displacement

Marc D. Hauser
Five experiments involving invisible displacements were run on a population of semi-free-ranging rhesus monkeys (Macaca mulatta). The goal of these experiments was to assess, without training, the kinds of expectations individuals spontaneously set up when an object has moved out of sight. The first experiment, modeled after studies of human infants and children, involved a table with one box on the top surface and a second box lined up below on the ground. An occluder was placed in front of the table, blocking the subject's view. A piece of food was then dropped behind the occluder, above the top box. The presenter then removed the occluder, walked away, and allowed the subject to approach. Consistently, subjects searched in the incorrect bottom box. This error can be interpreted as a failure to understand solidity, containment, or some other factor. It can also be interpreted as an error guided by a gravity bias, i.e. an expectation that all falling objects fall straight down or to the lowest point. Experiments 2,5 tested these alternative hypotheses. Results show that rhesus monkeys do not have an inherent bottom box bias, are not avoiding the top box, and do recognize that in some contexts boxes can contain or hold food. Thus, for example, when the two boxes are placed on the ground, one in front of the other, and occluded, subjects search in the near box after a piece of food has been rolled behind the occluder (horizontal trajectory). This shows that rhesus can solve an invisible displacement problem that involves solid containers, where one container blocks travel to the other container. We conclude that the rhesus monkey's error in Experiment 1 is guided by an expectation that all falling objects fall straight down or, at least, to the lowest point. This expectation represents a limitation of their knowledge of physical objects and events. [source]

Semantic confusion regarding the development of multisensory integration: a practical solution

Barry E. Stein
Abstract There is now a good deal of data from neurophysiological studies in animals and behavioral studies in human infants regarding the development of multisensory processing capabilities. Although the conclusions drawn from these different datasets sometimes appear to conflict, many of the differences are due to the use of different terms to mean the same thing and, more problematic, the use of similar terms to mean different things. Semantic issues are pervasive in the field and complicate communication among groups using different methods to study similar issues. Achieving clarity of communication among different investigative groups is essential for each to make full use of the findings of others, and an important step in this direction is to identify areas of semantic confusion. In this way investigators can be encouraged to use terms whose meaning and underlying assumptions are unambiguous because they are commonly accepted. Although this issue is of obvious importance to the large and very rapidly growing number of researchers working on multisensory processes, it is perhaps even more important to the non-cognoscenti. Those who wish to benefit from the scholarship in this field but are unfamiliar with the issues identified here are most likely to be confused by semantic inconsistencies. The current discussion attempts to document some of the more problematic of these, begin a discussion about the nature of the confusion and suggest some possible solutions. [source]

The ontogeny of diurnal rhythmicity in bed-sharing and solitary-sleeping infants: a preliminary report,

Melissa M. Burnham
Abstract The purpose of the current study was to investigate the development of sleep,wake and melatonin diurnal rhythms over the first 3 months of life, and the potential effect of bed-sharing on their development. It was hypothesized that increased maternal contact through bed-sharing would affect the development of rhythms in human infants. Ten solitary-sleeping and 8 bed-sharing infants' sleep,wake patterns and melatonin secretion were examined for 72 h at 1 and 3 months of age in their homes. Infants wore actigraphs on their ankles to study sleep,wake patterns. 6-Sulphatoxymelatonin was obtained through urine extracted from each diaper used over the 72-h study period. No significant differences were apparent in the timing of appearance or magnitude of sleep,wake or melatonin rhythms between bed-sharing and solitary-sleeping infants. Sleep,wake results were in the expected direction, with bed-sharing infants displaying more robust rhythms. A large degree of individual variability was evident in both rhythms, especially at 1 month. Three infants' parents regularly used a bright light source at night for feedings and diaper changes; the rhythms of these infants were less robust than the rest of the sample. Trends were mostly in the hypothesized direction and deserve attempts at replication with a larger sample. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Brain and behavior interface: Stress and the developing brain

Megan R. Gunnar
Animal studies have shown that mother,infant interactions can have long-term impacts on areas of the brain that regulate fearful behavior and the physiology of stress. Here, the research on human infants and children is reviewed with an eye to whether early experiences have similar effects in our species. Research shows that during the first year, sensitive and responsive caregiving becomes a powerful regulator of emotional behavior and neuroendocrine stress hormone activity in young children. Indeed, quality-of-care effects can be detected for children throughout the preschool years. Reviewed research suggests that temperament affects the likelihood that children will show increases in stress hormones as the quality of their care decreases. Finally, we review the literature on stress hormone activity in children who have been maltreated early in life, and explore the critical question of whether enhancing care later in development can reverse the effects on behavior and neurobiology of early adverse experiences. ©2003 Michigan Association for Infant Mental Health. [source]

Measurement of pulmonary surfactant disaturated-phosphatidylcholine synthesis in human infants using deuterium incorporation from body water

Paola E. Cogo
Abstract The aim of the study was to determine surfactant palmitate disaturated-phosphatidylcholine (DSPC-PA) synthesis in vivo in humans by the incorporation of deuterium from total body water into DSPC-PA under steady state condition. We studied three newborns and one infant (body weight (BW) 4.6 ± 2.9 kg, gestational age 37.5 ± 2 weeks, age 9 ± 9 days) and four preterm newborns (BW 1.3 ± 0.6 kg, gestational age 30.3 ± 2.5 weeks, postnatal age 8.8 ± 9.2 h). All infants were mechanically ventilated during the study and the four preterm infants received exogenous surfactant at the start of the study. We administered 0.44 g 2H2O/kg BW as a bolus intravenously, followed by 0.0125 g 2H2O/kg BW every 6 h to maintain deuterium enrichment at plateau over 2 days. Urine samples and tracheal aspirates (TA) were obtained prior to dosing and every 6 h thereafter. Isotopic enrichment curves of DSPC-PA from sequential TA and urine deuterium enrichments were analyzed by Gas Chromatography-Isotope Ratio,Mass Spectrometry (GC-IRMS) and normalized for Vienna Standard Mean Ocean Water. Enrichment data were used to measure DSPC-PA fractional synthesis rate (FSR) from the linear portion of the DSPC-PA enrichment rise over time, relative to plateau enrichment of urine deuterium. Secretion time (ST) was defined as the time lag between the start of the study and the appearance of DSPC-PA deuterium enrichment in TA. Data were given as mean ± SD. All study infants reached deuterium-steady state in urine. DSPC-PA FSR was 6.5 ± 2.8%/day (range 2.6,10.2). FSR for infants who did not receive exogenous surfactant was 5.7 ± 3.5%/day (range 2.6,9.9%/day) and 7.3 ± 2.1%/day (range 5.1,10.2%/day) in the preterms, whereas DSPC-PA ST was 10 ± 10 h and 31 ± 10 h respectively. Surfactant DSPC-PA synthesis can be measured in humans by the incorporation of deuterium from body water. This study is a simpler and less invasive method compared to previously published methods on surfactant kinetics by means of stable isotopes. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Matrix metalloproteinase-9 and tissue inhibitor of matrix metalloproteinase-1 in the respiratory tracts of human infants following paramyxovirus infection

Matthew B. Elliott
Abstract Respiratory syncytial (RSV) and parainfluenza (PIV) viruses are primary causes of acute bronchiolitis and wheezing illnesses in infants and young children. To further understand inflammation in the airways following infection, we tested for the presence of matrix metalloproteinases (MMP) and natural tissue inhibitors of MMP (TIMP) in primary and established human cell lines, and in the nasopharyngeal secretions (NPS) of human infants infected with RSV or PIV. Using ELISA and multiplex-based assays, MMP-9 and TIMP-1 proteins were, respectively, detected in 66/67 and 67/67 NPS. During PIV or RSV infection TIMP-1 concentrations were associated with hypoxic bronchiolitis. TIMP-1 amounts were also negatively correlated with O2 saturation, and positively correlated with IL-6, MIP-1,, and G-CSF amounts following RSV infection. IL-6, MIP-1,, and G-CSF were negatively correlated with O2 saturation during RSV infection. Acute respiratory tract disease was not associated with MMP-9 protein/protease activity. Additional studies using real-time quantitative PCR suggested that MMP-9 mRNA copy numbers were elevated in normal human bronchial epithelial (NHBE) cells infected with RSV, while TIMP-1 and TIMP-2 were not increased. However, ELISA did not reveal MMP-9 protein in the NHBE cell culture supernatants. Hence, the data implied that airway epithelial cells were not the primary source of MMP or TIMP following paramyxovirus infection. Taken together, the data suggested that paramyxovirus infection perturbs MMP-9/TIMP-1 homeostasis that in turn may contribute to the severity of respiratory tract disease. J. Med. Virol. 79:447,456, 2007. © 2007 Wiley-Liss, Inc. [source]

Neurochemical changes in the developing rat hippocampus during prolonged hypoglycemia

Raghavendra Rao
J. Neurochem. (2010) 114, 728,738. Abstract Hypoglycemia is common during development and is associated with the risk of neurodevelopmental deficits in human infants. The effects of hypoglycemia on the developing hippocampus are poorly understood. The sequential changes in energy substrates, amino acids and phosphocreatine were measured from the hippocampus during 180 min of insulin-induced hypoglycemia (blood glucose < 2.5 mmol/L) in 14-day-old rats using in vivo1H NMR spectroscopy. Hypoglycemia resulted in neuroglycopenia (brain glucose < 0.5 ,mol/g). However, the phosphocreatine/creatine (PCr/Cr) ratio was maintained in the physiological range until approximately 150 min of hypoglycemia, indicating that energy supply was sufficient to meet the energy demands. Lactate concentration decreased soon after the onset of neuroglycopenia. Beyond 60 min, glutamine and glutamate became the major energy substrates. A precipitous decrease in the PCr/Cr ratio, indicative of impending energy failure occurred only after significant depletion of these amino acids. Once glutamate and glutamine were significantly exhausted, aspartate became the final energy source. N -acetylaspartate concentration remained unaltered, suggesting preservation of neuronal/mitochondrial integrity during hypoglycemia. Correction of hypoglycemia normalized the PCr/Cr ratio and partially restored the amino acids to pre-hypoglycemia levels. Compensatory neurochemical changes maintain energy homeostasis during prolonged hypoglycemia in the developing hippocampus. [source]

Ethanol as a Reinforcer in the Newborn's First Suckling Experience

ALCOHOLISM, Issue 3 2001
Sarah J. Cheslock
Background: Recent evidence suggests that human infants prefer alcohol-flavored milk when fed through a bottle. Animal models also indicate a surprising predisposition for neonatal and infant rats to voluntarily and willingly ingest ethanol. These findings suggest high susceptibility to the reinforcing properties of ethanol early in ontogeny. Methods: A surrogate nipple technique,a highly effective tool for investigation of the reinforcing properties of different fluids,was applied in the present study. Tests of ethanol reinforcement were accomplished in terms of two basic paradigms of Pavlovian conditioning. In one paradigm, the conditioned stimulus (CS) was the surrogate nipple, and in the other, the CS was a novel odor. Results: Newborn rats showed sustained attachment to the nipple providing 5% ethanol, and later reproduced this behavioral pattern toward the empty nipple (CS alone). Ingestion of ethanol yielding appetitive reinforcement was accompanied by detectable blood alcohol concentrations, with most in the range of 20,30 mg/dl. The reinforcing efficacy of ethanol was also confirmed in the classical olfactory conditioning paradigm: following pairing with intraoral ethanol infusions, the odor (CS) alone elicited sustained attachment to an empty nipple. Females showed better olfactory conditioning with low concentrations of ethanol, whereas males were effectively more conditioned to high concentrations. Although there were no reinforcing consequences of intraperitoneally injected ethanol [as an unconditioned stimulus (US)] when a neutral odor was the CS, when paired with ingestion of water from a nipple, the injection of ethanol had a reinforcing effect. Conclusions: The present series of experiments revealed ethanol reinforcement in the newborn rat. Two varieties of Pavlovian conditioning established that ethanol can serve as an effective US, and hence reinforcer, in such a way as to increase the approach and responsiveness toward stimuli paired with that US, indicating appetitive reinforcement. [source]

Role of Lung Surfactant in Respiratory Disease: Current Knowledge in Large Animal Medicine

U. Christmann
Lung surfactant is produced by type II alveolar cells as a mixture of phospholipids, surfactant proteins, and neutral lipids. Surfactant lowers alveolar surface tension and is crucial for the prevention of alveolar collapse. In addition, surfactant contributes to smaller airway patency and improves mucociliary clearance. Surfactant-specific proteins are part of the innate immune defense mechanisms of the lung. Lung surfactant alterations have been described in a number of respiratory diseases. Surfactant deficiency (quantitative deficit of surfactant) in premature animals causes neonatal respiratory distress syndrome. Surfactant dysfunction (qualitative changes in surfactant) has been implicated in the pathophysiology of acute respiratory distress syndrome and asthma. Analysis of surfactant from amniotic fluid allows assessment of fetal lung maturity (FLM) in the human fetus and exogenous surfactant replacement therapy is part of the standard care in premature human infants. In contrast to human medicine, use and success of FLM testing or surfactant replacement therapy remain limited in veterinary medicine. Lung surfactant has been studied in large animal models of human disease. However, only a few reports exist on lung surfactant alterations in naturally occurring respiratory disease in large animals. This article gives a general review on the role of lung surfactant in respiratory disease followed by an overview of our current knowledge on surfactant in large animal veterinary medicine. [source]

Effects of low dose dexamethasone treatment on basal cardiovascular and endocrine function in fetal sheep during late gestation

Andrew J. W. Fletcher
This study investigated the effects on ovine fetal basal cardiovascular and endocrine functions of fetal intravenous dexamethasone treatment, resulting in circulating concentrations that were one-fifth of the values measured clinically in human infants following maternal antenatal glucocorticoid therapy. Between 117-120 days gestation (dGA; term: ca 145 dGA), 26 Welsh Mountain sheep fetuses were surgically prepared under general anaesthesia with vascular catheters and a Transonic flow probe positioned around a femoral artery. At 125 ± 1 dGA, fetuses were infused with dexamethasone (2.06 ± 0.13 ,g kg,1 h,1i.v.; n= 13) or saline (n= 13) for 48 h. Daily fetal arterial blood samples were taken and cardiovascular data were recorded continuously (data acquisition system). Pressor, vasoconstrictor and chronotropic responses to exogenously administered doses of phenylephrine, angiotensin II and arginine vasopressin (AVP) were determined at 124 ± 1 (pre-infusion), 126 ± 1 (during infusion) and 128 ± 1 (post-infusion) dGA. Fetal cardiac baroreflex curves were constructed using peak pressor and heart rate responses to phenylephrine. Dexamethasone treatment elevated fetal mean arterial blood pressure by 8.1 ± 1.0 mmHg (P < 0.05), increased femoral vascular resistance by 0.65 ± 0.12 mmHg (ml min,1),1 (P < 0.05), depressed plasma noradrenaline concentrations and produced a shift in set-point, but not sensitivity, of the cardiac baroreflex (P < 0.05). Elevations in fetal arterial blood pressure, but not femoral vascular resistance and the shift in baroreflex set-point, persisted at 48 h following dexamethasone treatment. By 48 h following dexamethasone infusion, basal plasma noradrenaline concentration was restored, whilst plasma adrenaline and neuropeptide Y (NPY) concentrations were enhanced, compared with controls (P < 0.05). Fetal dexamethasone treatment did not alter the fetal pressor or femoral vasoconstrictor responses to adrenergic, vasopressinergic or angiotensinergic agonists. These data show that fetal treatment with low concentrations of dexamethasone modifies fetal basal cardiovascular and endocrine functions. Depending on the variable measured, these changes may reverse, persist or become enhanced by 48 h following the cessation of treatment. [source]