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Query: UMLS:C0029713 (immaturity)
 4,335 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tiny babies have the potential problem of hypoglycemia due to diminished hepatic glycogen stores, which can be potentiated by conditions frequently present in this birth weight group: asphyxia, cold stress, hypoxia, polycythemia. Despite the early administration of fluid and feeding, tiny babies are still at risk for developing hypoglycemia. Their immaturity, expressed by their limited ability to tolerate parenteral glucose infusions, puts them at risk for becoming hyperglycemic as well. Hence careful glucose administration and frequent monitoring of blood glucose are essential during the first several days after birth, in anticipation of hypoglycemia as well as hyperglycemia.
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PMID:Perinatal glucose homeostasis: the unique character of hyperglycemia and hypoglycemia in infants of very low birth weight. 33 33

A greater dependence on transsarcolemmal Ca2+ flux and immaturity of Ca2+ sequestration capacity may potentiate Ca2(+)-mediated reperfusion injury in the newborn myocardium. The effect of serum ionized Ca2+ concentration on left ventricular systolic and diastolic function after ischemia was studied in 5-7-day-old piglets undergoing a 90-minute period of cold-blood cardioplegic arrest. In the control group, Ca2+ was maintained at 1.2 mM (Group A [n = 6]). The cardioplegic solution and bypass perfusate were modified to achieve a low Ca2+ concentration, 0.25 mM, in Group B (n = 6). Left ventricular pressure-volume loops were acquired by using high-fidelity pressure-sensor-tipped and volume-conductance catheters. Ventricular function was assessed from the slope of end-systolic (Ees) and end-diastolic (k) pressure-volume relations during transient caval occlusion. Both groups showed a significant reduction in Ees after ischemia (p less than 0.05). Intergroup comparison of Ees after ischemia demonstrated a better recovery of the systolic function in the low Ca2+ group, 64 +/- 7% versus 49 +/- 6% in the normal Ca2+ group (p = 0.05). There was a significant increase in chamber stiffness index in group A (k, 0.48 +/- 0.06 to 0.65 +/- 0.05 ml-1, p less than 0.01) versus no significant change in group B. This study shows 1) the feasibility of acquiring continuous pressure-volume data in neonatal hearts by using a conductance catheter system, and 2) better preservation of systolic function and diastolic compliance in normal newborn myocardium by low Ca2+ concentration in the peri-ischemic period.
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PMID:Effects of low perfusate Ca2+ concentration on newborn myocardial function after ischemia. 217 11

Some infants seem to be born with a degree of respiratory centre immaturity which in combination with other problems such as illness, head colds, exposure to cold, air or smoke, may result in cessation of breathing. Vestibular stimulation by rocking has been shown to be beneficial for premature babies in reducing apnea. There also appear to be other benefits, resulting in more rapid maturation of the nerve cells of the cerebellum which is still developing during the first six months of life. The suggestion is made that crib deaths may be reduced by the use of automatically rocking cribs, particularly during the night when most deaths occur.
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PMID:Sudden infant death syndrome and possible relation to vestibular function. 225 Oct 79

Pregnant rats were exposed to a cold environment (4 degrees C for almost the whole pregnancy) and the effects on the newborn rats' ventilation, metabolic rate and morphological lung appearance were examined. In cold-exposed rats oxygen consumption (VO2) increased during pregnancy and was 23% more than in control rats 1 day after delivery. All pups were born at term in litters of similar size. At 2-4 days after birth, in the pups born from cold-exposed mothers ("cold" pups), body weight (BW) and lung weight (LW) were reduced, with respect to control newborns, in a similar proportion. In "cold" pups the mean chord of subpleural alveoli was larger and lung volume smaller than in control pups. Both specific minute ventilation (VE/kg), measured by flow plethysmography, and specific oxygen consumption (VO2/kg), measured manometrically, were similar between the two groups. However, tidal volume/BW was smaller and breathing frequency higher in "cold" pups, a breathing pattern which appears necessary to fulfil normal metabolic requirements despite lung immaturity. These results suggest that cold exposure during pregnancy represents a maternal stress which results in somatic and pulmonary underdevelopment of the neonate.
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PMID:Cold exposure of the pregnant rat and neonatal respiration. 338 73

SIDS (Sudden Infant Death Syndrome) is the major cause of death in young, apparently healthy, infants, yet its etiology and pathogenesis remain unknown. SIDS peaks at 2-4 months, is more prevalent in the winter months and typically occurs in the early morning hours when most babies are asleep, suggesting that sleep may be part of the pathophysiological mechanism of SIDS. The sleep patterns of infants at high risk for SIDS were analyzed to test the hypothesis that there are abnormalities specific to nighttime sleep which may be indicative of a central nervous system (CNS) deficit that contributes to a high frequency of SIDS during the night. Electrophysiological sleep variables were recorded at monthly intervals in 1-6 months-old infants during the peak age of SIDS. The risk group (R) was resuscitated from a potentially life-threatening Sudden A-Ventilatory Event (S.A.V.E.) and compared to a group of control infants (C) with no family history of SIDS. The data representing four equal time intervals from 11 p.m.-11 a.m. show an abrupt, statistically significant increase in REM sleep from 2-5 a.m. in R infants. In C infants, time spent in REM sleep after 2 a.m. becomes progressively shorter while NREM sleep is proportionately longer. From 11 p.m.-2 a.m., however, R and C infants do not differ either in the duration or in the percent of total sleep time (TST) of REM sleep. We hypothesize that these REM sleep abnormalities in vulnerable infants are indicative of a pervasive CNS immaturity. The higher prevalence of SIDS in the cold winter months and in the early morning hours, when darkness is prolonged, is discussed in relation to the possible involvement of the circadian rhythm of melatonin.
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PMID:SIDS, abnormal nighttime REM sleep and CNS immaturity. 963 61

Muscular changes accompanying and/or promoting the rapid postnatal improvement of the thermogenic efficiency of shivering were investigated in piglets. Animals were obtained at birth or killed after 5 days at thermoneutrality (34-30 degrees C) or in the cold (24-15 degrees C), to stimulate intense shivering thermogenesis. Fast-twitch-glycolytic (longissimus lumborum) and slow-twitch-oxidative (rhomboid) muscles were prepared for electron microscopic examination and chemical measurements. Muscle-specific changes in energy stores and metabolism were observed after birth, including the switch from glycogen to lipids and variation of the lactate/pyruvate ratio corresponding to the progressive acquisition of the metabolic type of the mature muscles. There was major age-related and/or cold-induced development of the structures involved in excitation-contraction coupling (triadic profiles, +80% in the cold), oxidative metabolism (number of lipid droplets, +81% with age in the cold; number of mitochondria, +29% with age or cold; surface of mitochondrial inner membranes, +18% with age and +32% in the cold) and contraction potential (myofibril volume, +62% with age). In contrast, neither age nor cold affected capillary volume density and capillary-to-fibre ratio. The observed changes reflect the immaturity and remarkable plasticity of piglet skeletal muscle and are likely to underlie its enhanced capacity for shivering thermogenesis after birth.
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PMID:Effect of age and cold exposure on morphofunctional characteristics of skeletal muscle in neonatal pigs. 1219 14

The US measles epidemics of 1989-1991 included a series of outbreaks resulting from vaccine failure. A series of studies was launched aimed at elucidating the mechanisms of this vaccine failure. A meta-analysis of the literature examining epidemics in vaccinated populations was conducted, which showed that the secondary vaccine failure rate (development of the disease despite an initial or primary vaccine success) is no more than 0.2%. The overwhelming proportion of measles vaccine failure was due to primary vaccine failure (failure to ever generate antibody from antigenic stimulation). This comparison of two geographically distinct communities revealed that 10% of children previously vaccinated against measles lacked antibody on follow-up and that these vaccine failures clustered in families. A study of monozygotic and dizygotic twins revealed a high degree of heritability of measles vaccine antibody level. Subsequent studies found associations with both class I and class II alleles in these population-based studies. In the future, detection of the specific peptides that interact with human leukocyte antigen (HLA) molecules may serve as the basis for improved vaccines and address vaccine failure that results from cold-chain problems, immaturity of the immune system, malnutrition and maternal immunity.
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PMID:The genetic basis for measles vaccine failure. 1517 19

Extremely low-birthweight infants have inefficient thermoregulation due to immaturity and may exhibit cold body temperatures after birth and during their first 12 hours of life. Hypothermia in these infants can lead to increased morbidity and mortality. Anecdotal notes made during our recent study revealed extremely low-birthweight infants' temperatures decreased with caregiver procedures such as umbilical line insertion, intubations, obtaining chest x-rays, manipulating intravenous lines, repositioning, suctioning, and taking vital signs during the first 12 hours of life. Therefore, nursing interventions should be undertaken to prevent heat loss during these caregiver procedures. Nurses can improve the thermal environment for extremely low-birthweight infants by prewarming the delivery room and placing the infant in a plastic bag up to the neck during delivery room stabilization to prevent heat loss.
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PMID:Thermoregulation and heat loss prevention after birth and during neonatal intensive-care unit stabilization of extremely low-birthweight infants. 2083 82

Extremely low-birthweight infants have inefficient thermoregulation due to immaturity and may exhibit cold body temperatures after birth and during their first 12 hours of life. Hypothermia in these infants can lead to increased morbidity and mortality. Anecdotal notes made during our recent study revealed extremely low-birthweight infants' temperatures decreased with caregiver procedures such as umbilical line insertion, intubations, obtaining chest x-rays, manipulating intravenous lines, repositioning, suctioning, and taking vital signs during the first 12 hours of life. Therefore, nursing interventions should be undertaken to prevent heat loss during these caregiver procedures. Nurses can improve the thermal environment for extremely low-birthweight infants by prewarming the delivery room and placing the infant in a plastic bag up to the neck during delivery room stabilization to prevent heat loss. JOGNN, 36, 280-287; 2007. DOI: 10.1111/J.1552-6909.2007.00149.x.
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PMID:Thermoregulation and heat loss prevention after birth and during neonatal intensive-care unit stabilization of extremely low-birthweight infants. 1748 35

Pathological angiogenesis-driven by an imbalance of pro- and antiangiogenic signaling-is a hallmark of many diseases, both malignant and benign. Unlike in the healthy adult in which angiogenesis is tightly regulated, such diseases are characterized by uncontrolled new vessel formation, resulting in a microvascular network characterized by vessel immaturity, with profound structural and functional abnormalities. The consequence of these abnormalities is further modification of the microenvironment, often serving to fuel disease progression and attenuate response to conventional therapies. In this article, we present the "vascular normalization" hypothesis, which states that antiangiogenic therapy, by restoring the balance between pro- and antiangiogenic signaling, can induce a more structurally and functionally normal vasculature in a variety of diseases. We present the preclinical and clinical evidence supporting this concept and discuss how it has contributed to successful treatment of both solid tumors and several benign conditions.
Cold Spring Harb Perspect Med 2012 Mar
PMID:Vascular normalization as a therapeutic strategy for malignant and nonmalignant disease. 2239 32


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