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

Thyroid hormones influence fetal and neonatal lung growth and maturation. However, the effect of naturally occurring, genetically determined hypo- or hyperthyroidism on fetal or neonatal lung maturation has not been examined. In the hyt/hyt mouse, primary hypothyroidism, which is characterized by a high serum TSH concentration, is transmitted as an autosomal recessive trait. It occurs due to a mutational defect in the beta-subunit of the TSH receptor. We studied the lung ultrastructure of the fetal [18-d-gestation (term = approximately 19.5 d)] and neonatal (< 1-d-old) hyt/hyt mouse. In addition, disaturated phosphatidylcholine and total phospholipid contents of newborn hyt/hyt mouse lungs were determined. Male and female hyt/hyt mice with a high serum TSH concentration were made euthyroid by adding 3,5,3'-triiodothyronine to drinking water and then mated. Balb-c mice served as euthyroid controls. Fetal and neonatal hyt/hyt mice had a higher serum TSH concentration than the Balb-c controls. Fetal hyt/hyt mouse lungs showed a large amount of intracellular glycogen and fewer lamellar bodies in epithelial type II cells compared with Balb-c fetal mouse lungs. The neonatal hyt/hyt mouse also showed signs of lung immaturity such as persistent epithelial cell glycogen, few lamellar bodies, reduced disaturated phosphatidylcholine content, and absent tubular myelin. We conclude that fetal and neonatal lung maturation is delayed in the hyt/hyt mouse with primary hypothyroidism.
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PMID:Delayed ultrastructural lung maturation in the fetal and newborn hypothyroid (Hyt/Hyt) mouse. 780 36

The Jamaican Perinatal Mortality Survey provided the data for this logistic regression analysis of factors related to perinatal mortality. The sample included 94% of all mothers delivering in September and October 1986 and clinical records of still births and infant mortality with 7 days of birth during September 1986 and August 1987. Causes were identified according to the Wigglesworth classification as antepartum fetal deaths (APFD), congenital malformations and immaturity (IMMAT), intrapartum asphyxia (IPA), and miscellaneous. The results showed the lowest risk among married mothers and the highest among women with a visiting partner, but the relationship was not strong. Expenditures on food per person was unrelated. Unemployed women had a higher risk for all causes except immaturity. There were reduced risks for all deaths and IPA among households with heads engaged in professional and nonmanual skilled occupations. There was a strong relationship with the number of children under 11 years old in the household. The risk was very high in households with no children and risk declined with number of children under 11 years old. Housing size or type of ownership were unrelated. The more crowded the sleeping conditions, the lower the risk of perinatal death for IPA and all perinatal deaths. Risk was increased with lack of access to a private water supply in the household and use of shared toilet facilities. Increased risk was also related to lack of access to urban facilities. Risk was lowest in the eastern area of the island and highest in the far western areas. Lowest risks for all deaths were in the urban areas of Kingston, St. Andrew, and St. James. A U-shaped pattern appeared for age, with high risk among those under 17 years and over 35 years old for all deaths and IPAs. APFDs and IMMAT were more likely among mothers under 17 years old. Women taller than 5 feet 6 inches had the lowest mortality. APFDs and total perinatal mortality were significantly related to increased weight. Risk was increased among mothers either malnourished or obese. The final logistic model showed increased risk among mothers who were unmarried or cohabiting, with no young children regardless of parity, with shared toilet facilities, with lower nutrition, and increased age.
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PMID:Associations between social and environmental factors and perinatal mortality in Jamaica. 807 99

Distinct receptors mediate the vascular (V1) and renal (V2) effects of arginine vasopressin (AVP). Although ovine fetal AVP-induced antidiuresis can be demonstrated in early gestation (< 120 days; term 150 days), the early-gestation fetal renal responses to AVP are variable, including increases in urine flow and glomerular filtration rate (GFR). AVP V1 receptor predominance and/or V2 receptor system immaturity may contribute to variable early-gestation renal responses to AVP. To differentiate these possibilities, we assessed early-gestation fetal V2 receptor function in the presence and absence of V1 receptor-mediated effects by comparing the responses to AVP (a combined V1-V2 receptor agonist; n = 10; 112 +/- 2 days) with the selective V2-receptor agonist 1-desamino-8-D-arginine vasopressin (DDAVP) (n = 5; 111 +/- 2 days). AVP infusion increased fetal mean arterial pressure (MAP; 36 +/- 1 to 44 +/- 2 mmHg) and decreased heart rate (197 +/- 2 to 171 +/- 3 beats/min); DDAVP infusion had no effect on MAP or heart rate. Free water clearance decreased in response to AVP (0.13 +/- 0.02 to 0.02 +/- 0.01 ml.min-1.kg-1) and DDAVP (0.21 +/- 0.04 to 0.04 +/- 0.02 ml.min-1.kg-1), and urine osmolality increased in response to both analogues (AVP: 145 +/- 4 to 283 +/- 15 mosmol/kgH2O; DDAVP: 146 +/- 5 to 244 +/- 32 mosmol/kgH2O).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Vascular effects alter early-gestation fetal renal responses to vasopressin. 816 Aug 65

The renal effects of endothelin-1 were investigated in 16 anesthetized and mechanically ventilated newborn rabbits. Renal blood flow and glomerular filtration rate were determined by the clearance of para-aminohippuric acid and inulin, respectively. Each animal acted as its own control. In eight newborn rabbits, a bolus injection of 5 nmol.kg-1 of endothelin-1 caused an initial fall in mean arterial blood pressure followed by a gradual, significant increase in mean arterial blood pressure that lasted for 45 min. The dramatic increase in renal vascular resistance (+28 +/- 4%) induced by endothelin led to a fall in glomerular filtration rate (-12 +/- 4%) and renal blood flow (-16 +/- 3%). In spite of the reduction of glomerular filtration rate and renal blood flow, urine flow and sodium excretion rates increased significantly (+20 +/- 5% and +49 +/- 9%, respectively). In eight additional newborn rabbits, a bolus injection of 1 nmol.kg-1 of endothelin--a dose that usually induces marked renal and systemic vasoconstriction in adult models--did not affect systemic or renal hemodynamics. In conclusion, endothelin induces renal and systemic vasoconstriction and affects water and sodium homeostasis during the neonatal period. These effects occur under higher doses than those used in adult animals. This age difference in systemic and renal responsiveness is probably mediated by receptor immaturity and/or interference of high levels of counteracting hormones present during the neonatal period.
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PMID:Effects of endothelin on renal function in newborn rabbits. 823 10

The epidermal permeability barrier is provided by intercellular lipids forming multiple membrane bilayers in the stratum corneum. In the fetal rat, the barrier to transepidermal water loss forms during the 20th d of gestation and is accompanied by 1) increasing stratum corneum thickness; 2) increasing stratum corneum lipid content, particularly nonpolar ceramide and cholesterol content; and 3) the formation of lamellar unit structures throughout the stratum corneum interstices. In this report, we demonstrate that among pups of 20 d gestational age increasing barrier competence is correlated with increasing fetal weight. It has been previously demonstrated that fetal rats subjected to intrauterine growth retardation (IUGR) exhibit a thinner stratum corneum and decreased content of differentiation-specific epidermal structural proteins. To determine whether IUGR fetal rats also exhibit immaturity of barrier function and the barrier membrane system, maternal rats underwent unilateral uterine vessel ligation on d 17 or 18 of gestation and IUGR and control littermates were harvested on d 20, 21, or 22 of gestation for determination of transepidermal water loss. Despite significant somatic growth retardation and a thinner stratum corneum, barrier function in IUGR fetal rats did not significantly differ from that in control littermates at any gestational age. In both IUGR and control fetal rat epidermis at 21 d gestational age, lipids were deposited in a membrane pattern as visualized by nile red fluorescence microscopy and formed lamellar unit membrane structures throughout the stratum corneum intercellular domains as observed by electron microscopy.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Preservation of permeability barrier ontogenesis in the intrauterine growth-retarded fetal rat. 847 25

Kasabach-Merritt syndrome is characterized by thrombocytopenia and bleeding tendency leading to disseminated intravascular coagulation with giant hemangiomas. We present a very low birth weight infant with this syndrome who underwent four operations. A male baby (1179 g, 37 cm) was born at a gestational age of 28 weeks and 6 days by caesarean section. A large hemangioma, 7 x 8 cm in size, was recognized on the left thigh. As associated consumption coagulopathy (Kasabach-Merritt syndrome) was diagnosed with platelet count 5.1 +/- 10(4) mm-3 and fibrinogen 49 mg.dl-1. Despite treatment with liniac X-ray radiation, systemic steroid and component transfusion, coagulopathy became worse with extremely low platelet count of 1.1 x 10(4) mm-3. Infusion of dopamine and dobutamine was necessary for high output cardiac failure. On day 9, PDA ligation was performed. Cerebro-ventricular drainage, ventricuro-peritoneal shunt and shunt revision were required on day 15, 49 and 88, respectively, for hydrocephalus due to intraventricular hemorrhage. Main anesthetics used were fentanyl and sevoflurane. Major problems encountered by anesthetists were: bleeding tendency, water and electrolyte management, body temperature control, and immaturity and fragility of premature infant. Coagulopathy in Kasabach-Merritt syndrome must be a risk factor for intraventricular hemorrhage, which is a characteristic complication of a very low birth weight infant.
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PMID:[Anesthetic problems in a very low birth weight infant with Kasabach-Merritt syndrome]. 881 2

The skin of the extremely preterm infant is structurally and functionally immature at birth, although there is rapid postnatal maturation. The consequences of this immaturity are a high transepidermal water loss (leading to hypothermia and difficulty in fluid balance) accidental percutaneous absorption and toxicity, and skin trauma (leading to infection). Neonatologists must be aware of these and take measures to limit them.
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PMID:The immature skin. 883 41

Dietary intake, bacterial metabolites, and the secretion of factors (eg, proteins, electrolytes, lipid-soluble molecules, and water) by the body each contribute to the physicochemical environment of the gastrointestinal tract. Peristalsis regulates the changes along the length of the intestine. However, coordinated peristaltic responses develop as premature infants mature. In addition, the physicochemical environment of the center of the intestinal lumen differs from that of the epithelial surface. The area adjacent to the small intestinal epithelium is more acid than the bulk phase. Na+/H+ exchange antiporters in the epithelial cell apical membrane generate this acidity. Mucus maintains the acid microclimate by preventing free diffusion of hydrogen ions into the bulk phase. Development also affects these mechanisms. Changes in the lumenal environment may alter the synthesis of signaling molecules expressed by the intestinal epithelium. Thus, the epithelium, through changes in gene regulation, may act as an active interface that transmits information about the composition of the intestinal lumen to the mucosal immune system. Premature neonates are at risk of necrotizing enterocolitis, a disease almost exclusively associated with oral feeds. The pathogenesis of this condition may, in part, be due to the immaturity of the interactions between the physicochemical environment of the lumen and intestine.
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PMID:The physicochemical environment of the neonatal intestine. 1023 45

A significant increase in the water permeability was found in the rat outer medullary collecting duct (OMCD) cells in presence of 10-7M of vasopressin. The latter caused a decrease in the OMCD cell volume in isoosmotic medium in adult rats. In pups, the water permeability of the OMCD cells was very high. Vasopressin seems to be unable to decrease the cell volume of the OMCD cells in pups which suggests an immaturity of the cell transduction mechanism.
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PMID:[Morphometric analysis of the effects of vasopressin in the rat kidney collecting tubules]. 1038 87

Recent advances in neonatology and dermatology have provided us with a better understanding of neonatal and premature infant skin. The problems associated with immature skin become evident immediately after birth and require constant attention throughout the neonatal period. As advances in neonatal care push the gestational age of viability lower, skin maturation and function become increasingly important clinical problems. Premature skin immaturity contributes to elevated water loss, problems with electrolytes and thermoregulation, increased risk of local or systemic infection, increased uptake of potentially toxic agents, and vulnerability to trauma. This review discusses the unique nature of dermal structure and function in very low birth weight infants, evidence of mechanical fragility, toxicity of various topical agents, and the use of emollients. The opinions expressed are those of the authors and do not necessarily represent the views of the Navy or Department of Defense.
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PMID:Neonatal dermatology. 1055 1


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