Half Year Of Life Research Articles

The thymic size in children: a preliminary sonographic study

It is usually believed that the size of the thymus increases up to the age of one year and perhaps it increases even until puberty. We performed a sonographic assessment of the thymic volume in nine healthy term infant 3–7 times within the first one-and-a half years of life. We found that the thymic size increased only during the first 6 months of life and then it decreased. Two children were atypical in that the size of the thymus increased again after 6 months of age. We suspect that the thymic size may be affected by infections and feeding modes and ongoing larger sonographic studies will hopefully reveal this.

Infant expectations and reaction time as predictors of childhood speed of processing and IQ.

A longitudinal study investigated the relation between infant expectations and reaction time (RT) and childhood IQ and RT. Measures of visual anticipation and visual RT were taken at 3.5 months and 4 years of age. In addition, manual RT and verbal and performance IQ were measured at 4 years of age. Infant visual RT correlated reliably with childhood visual RT, and infant performance correlated significantly with childhood IQ. Childhood performance also correlated with concurrent childhood IQ. Children were slower to initiate eye movements when a manual choice button press was required than when it was not required. This load effect decreased as IQ increased. Visual RT and manual RT in childhood correlated only marginally. These are the first data to suggest stability in RT between early infancy and childhood or predictability from infant RT and anticipation in the first half-year of life to childhood IQ.

Missing effects of background dioxin exposure on development of breast-fed infants during the first half year of life

Fetal exposure to higher levels of PCBs can result in low birth weight and neurological disorders of the newborn. In this study the effects of exposure to the highly toxic dioxins and dibenzofurans, structurally related to PCBs, was investigated in a population of 38 healthy infants. The infants were divided into two groups, according to concentrations of dioxins and dibenzofurans in their mothers milk fat. Neonatal body weight, length, Quetelet index and liver size were determined at different time points during the first half year of life. Additionally neurological development was determined. Comparing these items between the high and low exposure groups did not show any statistically significant differences. The results of this study do not reveal any effect of exposure to background levels of dioxins and dibenzofurans, but in utero exposure to these toxic agents may result in symptoms later in life. Therefore follow-up study of this well defined group will be performed.

Standards for total body fat and fat-free mass in infants.

Data on body composition in conjunction with reference centiles are helpful in identifying the severity of growth and nutritional disorders in infancy and for evaluating the adequacy of treatment given during this important period of rapid growth. Total body fat (TBF) and fat-free mass (FFM) were estimated from total body electrical conductivity (TBEC) measurements in 423 healthy term Caucasian infants, aged 14-379 days. Cross sectional age, weight, and length related centile standards are presented for TBF and FFM. Centiles were calculated using Altman's method, based on polynomial regression and modelling of the residual variation. The TBF percentage steeply increased during the first half year of life, and slowly declined beyond this age. Various simple TBEC derived anthropometric prediction equations for TBF and FFM are available to be used in conjunction with these standards. Regression equations for the P50 and the residual SD, depending on age, weight, or length, are provided for constructing centile charts and calculating standard deviation scores.

The humoral immune response of children and infants to an RSV infection: its maturation and association with illness

In this study the immune response of 29 newborns and infants hospitalized on behalf of a RSV infection was evaluated. Acute phase and convalescent sera were examined by a neutralization assay, in an immunoblot, and in an ELISA based on 10 synthetic peptides derived from RSV proteins. The last two tests allow to monitor the synthesis of RSV specific antibodies of the infant. Despite the presence of maternal antibodies the initial immune response seems to be random and favours linear epitopes of the protein backbone of viral proteins. The earliest protecting antibodies directed against glycosylated epitopes are acquired in the second half year of life. Antibodies generated during the primary immune response seem to predispose infected children to get ill.

Development of linear and non-linear properties of heart rate control during quiet and active sleep in healthy infants

In this study it is analyzed by linear and non-linear methods, how the control of instantaneous heart rate (IHR) develops in infants in quiet and active sleep. Ten healthy and term newborns were studied during their first half year of life. Low (LF) and high frequency power (HF) of the spectrum, and the largest Lyapunov exponent (LLE) were calculated from IHR. By means of the surrogatedata-test, significance of LLE with respect to linear correlated gaussian noise was verified. Significant differences were determined between the original and the surrogate data sets (p< 0.001) assuming non-linear properties. LF, HF, LLE have irregular developmental patterns during the first month, whereby LLE has a distinct low value on the 21st day. HF significantly increases between the second and sixth month in quiet sleep, whereas for LF and LLE no significant correlations were found, neither for quiet nor active sleep. Using linear and non-linear methods, the study shows that the system controlling heart rate pass through mainly two different developmental periods: a period of adaptation in the first four weeks, where parameters distinctly vary, followed by a period with clear developmental courses, lasting till the sixth month.

Development of inferior temporal cortex in the monkey.

Inferior temporal (IT) cortex is critical for visual pattern recognition in adult primates. However, the functional development of IT cortex appears to be incomplete until late in the first year of life in monkeys and probably beyond. Responses of neurons in IT are substantially weaker, of longer latency, and more susceptible to anesthesia within at least the first half year of life. In addition, refinement of connections of IT, particularly those with regions in the opposite hemisphere and with regions related to memory and attention, continues for at least several months after birth. Moreover, many of the pattern recognition functions that IT supports in adulthood themselves show a very protracted period of development, and damage to IT cortex in infancy appears to have relatively little effect on pattern recognition abilities, despite the pronounced effects of comparable damage in adulthood. These findings all suggest that IT undergoes an extended period of postnatal development, during which both visual experience and the maturation of other brain structures may contribute to the emergence of mechanisms of pattern recognition within IT. In other respects, fundamental characteristics of IT emerge quite early. For example, despite their weaker responses, IT neurons have adult-like patterns of responsiveness--including pronounced form selectivity and large bilateral receptive fields--as early as we were able to test (approximately 6 weeks). Thus, IT cortex appears to be prewired with (or predisposed to develop rapidly) neural circuitry sufficient to produce basic properties remarkably similar to those found in the adult animal. Future studies of IT cortex will need to address the development of signals related to perceptual constancies and to formation and retrieval of visual object memories, the development of interactions with other regions involved in visual recognition (particularly frontal cortex), and the specific mechanisms underlying various types of plasticity present in IT cortex in both developing and mature primates.

Arachidonic acid immunoregulation in lambs persistently infected with border disease virus

To evaluate arachidonic acid-related immunoregulatory mechanisms during long-term persistent pestivirus infection, we measured plasma contents of leukotriene C4 (LTC4), prostaglandin D2 (PGD2) and their plasma fatty acid (FA) precursor, arachidonic acid (AA), in six lambs with congenital border disease (BD). Significantly elevated average plasma LTC4 during the first half year of life was associated with increased PDG2 when compared to uninfected control lambs. Significantly elevated total plasma esterified AA stores suggest an effective BDV-mediated prostenoid immunostimulation. However, at 1 yr old, prostenoid secretion had fallen to normal (LTC4) or below normal (PGD2) levels. In contrast, there remained significantly elevated plasma esterified AA, present as available substrate for formation of these anti-viral immunoregulatory agents. These results suggested that preventing mobilization of AA from lipid stores for effective immune responses may be a viral strategy of BD virus that is associated with long term border disease effects.

Clinical peculiarities and some neurophysiologic aspects of the spastic syndrome in children aged one year

The results of clinical and electrophysiologic examination of 116 children aged one year with spastic syndrome are presented. Neurosonographic examination shows the organic changes in brain tissue which manifest themselves as edema and periventricular infiltration in newborns and as ventriculomegalia of different manifestations in infants. The dopplerograms show the descrease of blood flow rate and change of resistance index. The sings of the decrease of the threshold of spastic readiness prevail in children in the second half year of life.

Effects of reducing the mother's radius of action on the development of mother-infant relationships in longtailed macaques

Abstract. Longtailed macaque, Macaca fascicularis, mothers, but not their infants, were limited in their radius of action to a small part of the harem-group cage. The behaviour of infants and the mother-infant relationship in these restrained dyads and in unrestrained dyads were compared during the first half year of life. Restraining the mother had no effect on the mother-infant relationship. Furthermore, there was only one effect on the infants' development, namely that infants of restrained mothers were on average 11 weeks older when they went beyond arm's reach of their mothers. This retardation in development of these infants' radius of action can be explained by infants being unwilling to enter the unfamiliar environment which could not be explored with the mother nearby.

Linguistic Experience Alters Phonetic Perception in Infants by 6 Months of Age

Linguistic experience affects phonetic perception. However, the critical period during which experience affects perception and the mechanism responsible for these effects are unknown. This study of 6-month-old infants from two countries, the United States and Sweden, shows that exposure to a specific language in the first half year of life alters infants' phonetic perception.

Transcutaneous Oxygen and Carbon Dioxide during the First Half Year of Life in Premature and Normal Term Infants

Repetitive polysomnograms were recorded from a total of 33 infants, 19 healthy preterm infants, and 14 term controls between 40 wk postconceptional age and 6 mo of age. These nighttime recordings lasted 2-4 h, except at 52 wk in preterm infants and at 3 mo of age in term infants when an overnight 12-h recording was performed. Minute by minute values of transcutaneous PO2 (PtCO2) and transcutaneous PCO2 (PtcCO2) levels and variability during the awake state, active sleep, and quiet sleep were obtained through computer analyses of the polygraphic data. The results from preterm infants at corrected postconceptional age could not be differentiated from those of control infants. PtCO2 levels rose between 40 wk and 3 mo, and PtcCO2 levels declined. Sleep states modulated only the variability of PtcO2, not the level; in contrast, state modulation was seen in both variability and level of PtcCO2 throughout the age span studied. During sleep the number of transient declines in PtCO2 greater than 2.03 kPa (15 mm Hg) decreased with advancing age. Hypercapnic PtcCO2 values decreased with age as well, but their prevalence in healthy, young infants suggests the need for reevaluation of criteria for hypercapnia based on transcutaneous measurements. The data demonstrate that ventilatory regulation continues to undergo changes between 1 and 3 mo, the age of highest risk for sudden infant death syndrome.

Maternal unresponsiveness and infant crying across the first 9 months: A naturalistic longitudinal study

In this longitudinal study of 50 mother-infant dyads, it is hypothesized that maternal responsiveness, defined as promptness of maternal interventions to infant crying, decreases the number and duration of infant crying bouts. All subjects were visited 12 times at home at 3-week intervals during the first 9 months after the birth of the infant. The mean total observation period for every dyad was 21.7 hours. Data on frequency and duration of infant crying and maternal responsiveness were collected through event- and audiorecording equipment. Results show that average duration of crying is reduced by half from the first to the third quarter. Average frequency of crying bouts, however, remains the same. Individual differences in duration of crying cannot be explained by differences in promptness of maternal responsiveness to infant crying. However, individual differences in number of crying bouts at the end of the first half year can be partly attributed to differences in maternal responsiveness: More frequent delay of maternal responses reduces the number of crying bouts during the first half year of life. The concept of differential responsiveness is hypothesized to explain our unexpected results.

Malignant melanoma in transgenic mice.

Ocular and cutaneous melanomas arose in new inbred lines of transgenic mice having an integrated recombinant gene comprised of the tyrosinase promoter, expressed in pigment cells, and the simian virus 40 early-region transforming sequences. The tumors were hypomelanotic and were histopathologically similar to corresponding human melanomas. Eye melanomas often originated at a young age, chiefly from the retinal pigment epithelium, also from the choroid, and rarely from the ciliary body. The eye tumors grew aggressively, were highly invasive, and metastasized to local and distant sites. The earliest formation of these tumors was associated with higher copy numbers of the transgene; mice of different single-copy lines varied greatly in age of onset and frequency of eye tumors. Coat pigmentation was reduced in almost all lines, to various extents. Primary skin melanomas arose later and less frequently than eye melanomas. Hence they were at early stages and of unknown long-range incidence in this investigation, in which autopsies covered the first half-year of life. For both ocular and cutaneous melanomas, the transgenic mice offer numerous possibilities for experimental study of mechanisms underlying formation and spread of melanomas.

Whole Cow Milk Feeding Between 6 and 12 Months of Age? Go Back to 1976

In 1976, the Committee on Nutrition of the American Academy of Pediatrics recommended that the non-breast-fed infant receive an iron-fortified proprietary formula during the entire first year of life.1 In 1983, the Committee on Nutrition reversed the previous recommendation and concluded, "If breast-feeding has been completely discontinued and infants are consuming one third of their calories as supplemental foods consisting of a balanced mixture of cereal, vegetables, fruits, and other foods, whole cow milk may be introduced."2 The Committee, in their report, acknowledged the fact that "there are many unanswered questions concerning the use of whole cow milk in the second half year of life." I believe that we now have answers to some of these questions and that we should return to the original recommendation discouraging the use of whole cow milk (WCM) until infants have reached their first birthday. Studies performed since the 1983 report have demonstrated that the introduction of WCM prior to the first birthday is associated with an increased risk of occult gastrointestinal bleeding3 and an increased incidence of iron deficiency anemia.4,5 In addition, iron deficiency anemia in infants less than 1 year of age has been shown to be associated with cognitive and psychomotor impairment6-8; such impairment may not be correctable with iron therapy.7-9

Whole Cow Milk Feeding Between 6 and 12 Months of Age? Go Back to 1976

In 1976, the Committee on Nutrition of the American Academy of Pediatrics recommended that the non-breast-fed infant receive an iron-fortified proprietary formula during the entire first year of life.1 In 1983, the Committee on Nutrition reversed the previous recommendation and concluded, If breast-feeding has been completely discontinued and infants are consuming one third of their calories as supplemental foods consisting of a balanced mixture of cereal, vegetables, fruits, and other foods, whole cow milk may be introduced.2 The Committee, in their report, acknowledged the fact that there are many unanswered questions concerning the use of whole cow milk in the second half year of life. I believe that we now have answers to some of these questions and that we should return to the original recommendation discouraging the use of whole cow milk (WCM) until infants have reached their first birthday. Studies performed since the 1983 report have demonstrated that the introduction of WCM prior to the first birthday is associated with an increased risk of occult gastrointestinal bleeding3 and an increased incidence of iron deficiency anemia.4,5 In addition, iron deficiency anemia in infants less than 1 year of age has been shown to be associated with cognitive and psychomotor impairment6-8; such impairment may not be correctable with iron therapy.7-9

Social Relations in Groups of the Black-Capped Capuchin (Cebus apella) in Captivity

During the second half-year of life, capuchin monkey infants maintain close contacts to kin-related animals. Apart from these contacts, they frequently interact with other infants and juveniles 1 year older. During this period of life the 'peer phase' begins in the life of the infants. Furthermore, gender differences, especially in respect to social play, become obvious.

Polysomnographic Sleep and Waking States Are Similar in Subsequent Siblings of SIDS and Control Infants During the First Six Months of Life

Twenty-five subsequent siblings of infants who died of Sudden Infant Death Syndrome (SIDS) underwent 12-h overnight polygraphic recordings during the first week of life and at 1, 2, 3, 4, and 6 months of age. The polygraphic tracings from these infants were compared with those from 25 infants without a family history of SIDS. One dozen sleep and waking parameters were examined including state transition probabilities, the ratio between quiet sleep (QS) and active sleep (AS), the incidence and duration of sustained states and the stability of an infant's sleep and waking during the first half year of life. Variability within and between infants was marked with a reduction of variability in measures of QS at 3 months and of AS at 4 months of age. The similarities between subsequent siblings of SIDS and control infants far outweighted the differences. However, subsequent siblings exhibited a tendency, once asleep, to remain asleep longer than controls. This finding was observed in a comparison of 20 infants in each group. When five infants were added to each group, infants in both groups tended to awaken equally from QS, but once in AS the subsequent siblings tended to proceed into QS instead of awaken as the controls did.

The natural history of liver disease in alpha 1-antitrypsin deficient children.

During 1972-1974, 200,000 Swedish infants were screened for alpha 1-antitrypsin deficiency. Of 127 PiZ (Protease inhibitor) children followed from infancy to 12 years of age, four PiZ children with neonatal liver disease have died; two of liver cirrhosis, one was found to have liver cirrhosis at autopsy, having died of aplastic anemia and the fourth died in an accident. Liver microscopy showed a mild increase of periportal fibrous tissue. Another PiZ child died of anaphylactic shock. At 12 years of age, none of the PiZ children have clinical symptoms of liver disease. No PiZ-, PiSZ, PiS- or PiFZ child has had any clinical symptom of liver disease. One PiSZ child died of sudden infant death syndrome. Laboratory analyses from birth through 12 years of age have shown increased S-Bilirubin levels in 11% of the PiZ infants, which normalized within the first half year of life. S-GT was abnormal in about half of the infants, but had normalized when checked at 8 and 12 years of age in all but 6-3% of the PiZ children. The percentage of abnormal S-ALAT test results have decreased from 73% during the first year of life, to about 15% at the age of 12. The range of the abnormal levels also decreased considerably. Abnormal S-GT or S-ALAT levels were found in about 20% of the PiSZ infants, the proportion decreasing to 2% at the age of 12.

Vernier acuity is less than grating acuity in 2- and 3-month-olds

Vernier acuity and grating acuity were measured longitudinally starting at 1 or 2 months of age in 22 infants, using a two-alternative, forced-choice preferential looking technique. For vernier acuity, the motion-sound display was employed. For grating acuity, a preferential looking method was employed. Steps of the stimulus (vernier offset and spatial frequency of the grating) and procedures were basically identical between the two acuity tests. The range of stimuli was set so as to compare the two acuities at younger ages. Results show: (1) vernier acuity is less than grating acuity at 11–12 weeks of age or younger, and (2) the developmental rate of vernier acuity is greater than that of grating acuity in the first half-year of life. To interpret the data, it was speculated that: (1) the mean sampling distance (center-to-center distance between receptive fields) may influence vernier acuity more than grating acuity, whereas the size of the receptive field may influence grating acuity more than vernier acuity: (2) when the mean sampling distance is large relative to the size of the receptive field, vernier acuity may be less than grating acuity. Thus, the neonatal visual system, just as the visual system in the periphery and in strabismic amblyopia, may be characterized by spatial undersampling.