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At least 19 recordsLinked to original sources
PubMed1984

The postnatal physiological and neurochemical development of peripheral sensory C fibres.

The postnatal development of sensory C fibre function was investigated in neonatal rats aged 1-21 days. From birth, flexor-withdrawal reflexes (measured from the hamstring electromyograph) to pinching and heating the skin of the hindfoot were easily recorded under light anaesthesia and in fact were exaggerated in amplitude and duration compared to adult responses. Flexor reflexes to irritant chemicals, however, were not present until day 10-11 of life. In parallel with this late development of specific chemical sensitivity, neurogenic oedema, a C fibre-mediated inflammatory reaction, also did not occur until day 11. Substance P and fluoride-resistant acid phosphatase histochemistry were used to investigate the neurochemical development of sensory C fibres. Substance P was present in the skin, nerve, dorsal root ganglion and spinal cord from birth and fluoride-resistant acid phosphate within 12 h of birth. The adult neurochemical appearance of C-fibre terminals in the dorsal horn was established in a few days. The results show that despite the apparent early anatomical and neurochemical maturity of C fibres, physiological function is not fully established until the second week of life.

Acid Phosphatase↗
PubMed2003

[Postnatal physiological development of rats after acute prenatal hypoxia].

The aim of study was to investigate the physiological development of the brain and behaviour in rats subjected to prenatal hypoxia on the 13.5th day of embryogenesis. We have found that such rats manifested a delayed physiological development and a change in nervous tissue of the sensorimotor cortex, as well a disturbed formation of motor responses during the first month of postnatal ontogenesis. During maturation these modifications were in part compensated, however we observed a decrease of the rats' ability to learn new forepaw movements. The destruction of the brain tissue and the modification of neurons composition in the sensorimotor cortex correlated with changes of behaviour at different stages of ontogenesis. Thus, changes of the conditions under which an organism develops during embryogenesis, predetermine a disturbance in ontogenesis and the learning ability.

Acute Disease↗
PubMed2004

Postnatal physiological development of rats after acute prenatal hypoxia.

The aim of the present work was to identify the characteristics of the physiological development of the brain and the formation of behavior in rats subjected to hypoxia on day 13.5 of embryogenesis. These animals showed delayed development and changes in nerve tissue structure in the sensorimotor cortex, along with disturbances to the processes forming normal movement responses during the first month after birth. These changes were partially compensated with age, though adult animals subjected to acute prenatal hypoxia were less able to learn new complex manipulatory movements. Alterations in nerve tissue structure and changes in the neuronal composition of the sensorimotor cortex correlated with the times of appearance of behavioral impairments at different stages of ontogenesis. Thus, changes in the conditions in which the body is formed during a defined period of embryogenesis lead to abnormalities in the process of ontogenetic development and the ability to learn new movements.

Animals↗
PubMed1981

Postnatal physiologic hypercholemia in both premature and full-term infants.

Previous studies have shown that bile salt concentrations in human blood taken from the placenta at birth of term infants are in the range found in adults. A 125I-radioimmunoassay procedure and capillary gas liquid chromatography-mass spectrometry have been used in this investigation to measure serum bile salt concentrations in premature and normal term infants. It was found that the serum bile salt concentration in samples taken at birth in premature infants were also similar to that of adults. In the week after birth the serum bile salt concentration rose four- to sevenfold in each of the infant groups. The increase was independent of gestational age and the "health" of the child. A similar increase was observed in term infants. Thus, hypercholemia is physiologic in newborn infants. In conjunction with other abnormalities of the enterohepatic circulation of bile salts there are profound implications in the newborn for the metabolism and excretion of those endogenous and exogenous substances that are dependent on the secretion of bile salt by the liver. In addition, speculations concerning the role of parenteral nutrition in the induction of cholestasis in premature infants should be made with caution.

Age Factors↗
PubMed2006

Postnatal - physiological research of the bronchial receptor system development on the isolated preparation of the human trachea in vitro.

Research was done on pharmacological-physiological development of the bronchial receptor system on the smooth muscles of trachea in the newborn children, alive-born and stillborn children. Monitored was the response on: acetylcholine, dopamine, histamine and serotonin in different molar concentrations 10(-4), 10(-3), 10(-2), 10 mol/dm(-3), micromol/dm(-3)). Research was done on tonus of tracheal smooth muscles of 23 tracheal preparations taken by autopsy after death from different factors. Based on pharmacological-physiological research on the preparations of human isolated trachea it was find out that: acetylcholine stimulation effect is significant (p>0,01) in 38-41 weeks of pregnancy comparing with that in 30-37 weeks of pregnancy (p>0,01), while dopamine stimulation effect is significant (p>0,05) in 30-37 pregnancy weeks comparing with the effect of acetylcholine and dopamine on the still-born infants of the same pregnancy period (p<0,01). Histaminic receptors were developed during intrauterine life after 38 weeks of pregnancy (p>0,025). Serotonin has caused contraction of the bronchial smooth muscles after 30 pregnancy weeks, but response was not significant (p<0,01). This suggests that cholinergic and adrenergic system of the airways in alive newborn infants develops in parallel intrauterine, contrary to other systems which develop in certain extrauterine life phases.

Acetylcholine↗
PubMed2004

Early physiological development of infants with intrauterine growth retardation.

OBJECTIVES: To assess the patterns of early postnatal physiological adaptation and maturation in intrauterine growth retarded (IUGR) infants by measuring changes in sleeping deep body temperature, heart rate, and concentrations of urinary cortisol. SETTING: At home. PATIENTS: Sixty five IUGR babies and 127 controls matched for sex, social class, and levels of parental smoking. RESULTS: Night time sleeping deep body temperature, heart rate, and cortisol excretion fell with age, eventually establishing an adult type diurnal rhythm of physiological function. Minimum overnight temperature showed a linear decline with age (p < 0.001), but the IUGR infants and the controls had significant differences in intercept (p = 0.007) and slope (p = 0.02). The estimated rate of decline per week was 0.020 degrees C for IUGR infants and 0.031 degrees C for controls. Maximum temperature did not show similar changes. IUGR infants had a mean (SE) age adjusted minimum overnight heart rate that was 4.2 (1.5) beats/min (p = 0.005) higher than controls. Overnight cortisol/creatinine ratios declined with age at a rate of 4.1% per week (log ratio -0.421 (0.0165), p = 0.01), but the ratio for IUGR infants was on average 42% higher (log ratio 0.35 (0.11), p = 0.002) than for controls of the same age. Morning cortisol concentrations did not show a similar pattern. CONCLUSIONS: Postnatal physiological adaptation and maturation of IUGR infants is slower than normal and therefore they remain in a physiologically immature state for longer. The higher heart rates and greater cortisol excretion in such infants may be precursors to hypertension and cardiovascular disease seen in adults.

Adaptation, Physiological↗
PubMed1979

Longitudinal study of plasma testosterone in male pseudohermaphrodites during early infancy.

Plasma testosterone was longitudinally studied during the first months of life in 7 XY infants with male pseudohermaphroditism. In two, the physiological postnatal rise of plasma testosterone was absent or blunted. A combined adrenal and testicular enzymatic defect was demonstrated in these two boys. In 5, a normal postnatal testosterone rise demonstrated a normal Leydig cell function. The longitudinal study of the physiologic postnatal rise of testosterone may be useful to distinguish secretory defects from responsiveness abnormalities thus improving the choice of gender in male pseudohermaphrodites.

Age Factors↗
PubMed2006

Effects of twinning, birth size, and postnatal growth on glucose tolerance and hypothalamic-pituitary-adrenal function in postpubertal sheep.

Low birth weight is associated with postnatal physiological changes, including impaired glucose tolerance and increased cortisol secretion, that may predispose to disease in adulthood. Twins are born lighter than singletons, but there are conflicting data regarding the association between birth weight and postnatal physiology in twins. We studied glucose tolerance and ACTH and cortisol responses to a combined corticotropin-releasing hormone and arginine vasopressin (CRH + AVP) challenge in postpubertal female twin (n = 7 twin pairs) and singleton (n = 13) sheep from the same flock. There were no differences in glucose tolerance between twins and singletons and no association with birth weight. Twins had a greater ACTH (P < 0.05), but not cortisol, response to CRH + AVP than singletons. ACTH area under the curve was inversely related to birth weight in both singletons [R(2) = 0.31, P = 0.05; -8,311 (SD 3,736) pg.min.ml(-1).kg(-1)] and twins (R(2) = 0.49); in twins, this was due to the within-twin pair rather than the between-twin pair coefficient in the regression analysis [P = 0.02, -26,856 (9,806) vs. P = 0.1, 8,619 (4,950) pg.min.ml(-1).kg(-1)]. We conclude that the reduced fetal growth in twins has postnatal consequences for hypothalamic-pituitary-adrenal function and that this is determined by factors specific to the fetus (within-twin pair) rather than by shared maternal factors (between-twin pair). Studies investigating the associations between fetal growth and postnatal outcomes in twins benefit from an appropriate singleton control group and from analyses evaluating the contribution from both between- and within-pair coefficients in twins.

Adrenocorticotropic Hormone↗
PubMed1991

[Physiology and physiopathology of postnatal pulmonary adaptation. 1: Physiology].

The aim of the review consists of the help to understand the complex physiological mechanisms of the onset of breathing and the regulation of the respiration during the early newborn period. The lungs of the newborn contain nearly no alveoli. Postnatal formation of alveoli enlarges the gas exchange surface until the 20th year of life, the lung volume increases by a factor of 27. Immediately postnatal the aeration of the lungs is performed by several deep inspirations with breath hold and following crying. The fetal lung liquid is resorbed via both, lymph and blood vessels. Stability of the functional residual capacity is reached very rapidly. The inflation augmenting reflex and sighing support effectively this process. The significant importance of the surfactant for the successful begin of air breathing is described. Onset of respiration is combined with the decrease of the pulmonary arterial resistance and the remarkable increase of the pulmonary blood flow. The hypoxic response in the newborn is biphasic. An initial short hyperventilation is regularly followed by ventilatory depression. Neurophysiological causes are evident. Hyperventilation by inhalation of gas mixtures with higher CO2 concentrations is low, at least in preterm infants. The causes are believed to ly in the limitation of the efficiency of the respiratory muscles. Peripheral chemoreceptors in the glomus caroticum and in the bronchial mucosa, stretch receptors in the bronchial muscles, and muscle spindles in the intercostal muscles are functioning in newborns as well as in preterm infants.

Adaptation, Physiological↗
PubMed2003

Comparative physiology of postnatal developments of cardiopulmonary reflex.

We analyzed and compared the frequency components of the heart rate variability in human neonate, rat, white chicken, turtle, and frog during the developments. Frequency analysis with autocorrelation-FFT method was applied to the heart rate and respiration waves to calculate the respiration induced frequency component in the power spectra. The comparative analysis of the cardiopulmonary reflex in human and rat neonates resulted in a similar developmental progress. In case of human immature neonate, respiration induced frequency component in the heart rate variability was negligible at day-old 0, and significantly increased at postnatal 1 month. The rat neonates also showed no or negligible respiration induced components until days 8 and it became significant approximately postnatal 1 month. The white chicken also indicated negligible respiration induced component before and a few days after hatching, and became significant after 38 days-old (17 days post hatching). However the frog and the turtle indicated no clear response in entire periods of the development even in adult. The results strongly suggested that gravity may be a possible essential factor of the appearance of the post natal development of the cardiopulmonary reflex.

Animals↗
PubMed2003

Overnight deep body temperature and urinary cortisol excretion in infants from economically deprived areas.

OBJECTIVES: To assess the pattern of postnatal physiological maturation in economically deprived infants by measuring the age-related changes in deep body temperature during night-time sleep. SETTING: Inner city Leicester, UK. PARTICIPANTS: Forty-eight infants aged 6-21 weeks from economically deprived areas and 87 control infants from more affluent areas. OUTCOME MEASURES: Average deep body temperature between 2 and 4 h after bedtime, overnight and early morning urinary cortisol excretion. RESULTS: Both groups showed a decline in overnight deep body temperature with age that averaged 0.030 degrees C per week (SE = 0.003). Over the age range studied, the average age-adjusted overnight temperature in the infants from deprived homes was 0.090 degrees C (SE = 0.028) higher than that for the affluent group (P = 0.001). Deprived infants had on average 51% higher overnight urinary cortisol and 80% higher morning cortisol. The differences remained when the effects of room temperature, clothing, smoking, birthweight and gestational age were taken into account. CONCLUSION: These indicators of postnatal physiological maturation suggest that infants from economically deprived homes mature less quickly. This might increase their vulnerability to illness.

Age Factors↗
PubMed1986

Response of the maternal, fetal, and neonatal pituitary-thyroid axis to thyrotropin-releasing hormone.

Thyrotropin releasing hormone (TRH) readily crosses the placenta and stimulates the fetal pituitary. We studied the response of the maternal and fetal pituitary-thyroid axes to TRH and the influence of prenatal exposure to TRH on the physiological postnatal increase in thyrotropin (TSH) and triiodothyronine (T3) in the neonate. Twenty-six pregnant women received TRH (400 or 600 micrograms) intravenous or saline (controls) either 2 or 12 h before elective cesarean section at term. Administration of 400 micrograms of TRH resulted in significant elevations of maternal TSH (15.7 +/- 2.9 versus 3.2 +/- 0.4 microU/ml, p less than 0.01) and prolactin (416 +/- 94 versus 223 +/- 41 ng/ml, p less than 0.05) 2 h later. Maternal T3 remained unchanged. A higher dose of TRH (600 micrograms) produced comparable results. Maternal administration of TRH (400 micrograms) 2 h before delivery resulted in significant increases in fetal TSH and T3 over controls (21.1 +/- 3.7 versus 4.8 +/- 1.0 microU/ml, and 132 +/- 12 versus 64 +/- 9 ng/dl, p less than 0.01, respectively). Cord blood hormone levels 12 hours after TRH administration were similar to controls. Higher doses of TRH did not produce further increases in fetal TSH or T3. Control and treated neonates demonstrated similar physiological postnatal increases in TSH and T3, suggesting that prior exposure to TRH did not blunt this response. These data suggest that maternal administration of TRH is an effective way of increasing fetal T3 levels, and that this treatment does not inhibit the postnatal surge in TSH and T3.

Female↗
PubMed1988

A comparison of postnatal thermal physiology and energetics in an altricial (Gerbillus perpallidus) and a precocial (Acomys cahirinus) rodent species.

1. Daily weight increase is polyphasic in Gerbillus perpallidus whereas it follows a linear pattern in Acomys cahirinus. 2. Young A. cahirinus achieve full homeothermic capacities much earlier (less than or equal to 12 days old) than G. perpallidus (19-21 days old). 3. The differences in the development of the two species are reflected in the alterations of their metabolic rates. 4. In both species, age-dependent phases of development are obvious, beginning, however, much later in G. perpallidus. 5. It is concluded that, by postponing functional maturity, considerably more energy can be allocated to growth. This may be a precondition for the altricial mode of development.

Aging↗