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

In recent years increasing experimental and clinical data have provided compelling evidence for the involvement of oxygen free radicals in the 3 main disorders of prematurity--chronic lung disease, retinopathy of prematurity and intraventricular haemorrhage. Infants born prior to 30 weeks gestation or weighing less than 1500 g at birth appear to be most at risk. They are very underdeveloped and as a consequence of the immaturity of their lungs often require intense respiratory support, including the provision of supplemental oxygen. The theoretical basis for free radical involvement in these disorders is that oxygen centred radicals and related reactive oxygen metabolites are formed too rapidly to be detoxified by the antioxidant defence mechanisms in specific tissues. In the case of chronic lung disease, the evidence currently favours excess oxygen (hyperoxia) as the cause of the greater oxygen free radical production, whereas in retinopathy of prematurity and intraventricular haemorrhage, it is proposed that low oxygen tensions (hypoxia) followed by periods of reoxygenation is the more likely stimulus for excess radical formation.
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PMID:Free radical disorders of preterm infants. 822 Oct 31

Bronchopulmonary dysplasia of preterm infants has a multifactorial etiology. Pulmonary immaturity, oxygen toxicity, formation of oxygen radicals and mechanical lung trauma as well as additional factors (pulmonary hyperhydration, infection a.o.) may contribute to pulmonary damage. A pulmonary inflammatory reaction is thought to play a central role in the pathogenesis of chronic lung disease. It is characterized by the presence of inflammatory cells and various inflammatory mediators including proteases, chemoattractants, cytokines, leukotrienes and others. Due to the immaturity of several protective systems (antiproteases, antioxidants, surfactant system) the inflammatory response seems to be aggravated. Moreover, the magnitude and persistence of inflammation may eventually lead to pulmonary fibrosis.
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PMID:[Pathogenesis of bronchopulmonary dysplasia]. 852 53

Free radical-mediated oxidation of proteins may impair their function and cause cellular damage. We studied pulmonary protein oxidation and its association with the development of chronic lung disease in 61 newborn infants (mean gestational age 31.1 +/- 4.0, range 24-41 weeks) requiring intensive care with oxygen therapy. Protein oxidation was quantified as protein carbonylation in tracheal aspirates recovered daily during the first week of life. Mean carbonyl concentration was 3.5 +/- 1.6 mumol/mg protein. Negative correlations existed between protein carbonylation during days 2-4 and gestational age (day 2: r = -0.37, p = 0.01; day 3: r = -0.48, p = 0.001; and day 4: r = -0.33, p = 0.03). Patients who developed bronchopulmonary dysplasia showed significantly higher protein carbonylation on days 1-6 (all p < 0.05). In multiple regression analysis explaining bronchopulmonary dysplasia, using gestational age, inspired oxygen on days 1-3 and protein carbonylation on day 3 as independent variables, only protein carbonylation remained significant. We conclude that immaturity is the most important factor explaining free radical-mediated pulmonary protein oxidation in newborn infants and that oxidation of proteins is related to the development of chronic lung disease.
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PMID:Early protein oxidation in the neonatal lung is related to development of chronic lung disease. 858 Jun 30

Bronchopulmonary dysplasia (BPD), a respiratory disorder first described in prematurely born infants with respiratory distress syndrome (RDS) treated with mechanical ventilation and oxygen supplementation, is the most common cause of chronic lung disease in infants. It is defined as the need for increased inspired oxygen at 28 days of age, and is observed with the highest frequency following premature delivery of very low birth weight infants. Indeed, an incidence of 48% has been recently reported in a population with a mean gestational age of 27 weeks. The etiology of BPD is multifactorial including lung immaturity, respiratory distress, oxygen therapy, and mechanical ventilation. Based on the current understanding of the pathogenesis of the disease, several therapeutical strategies are used. One of them is focused on the prevention of BPD by correcting surfactant deficiency in premature infants with RDS using exogenous surfactant, and also by improving the techniques of mechanical ventilation used for the management of RDS. Another approach which is being developed is focused on the factors involved in the processes of repair of the injured immature lung. These factors include the use of inhibitors of the inflammatory cascade, antioxidants, and inhibitors of fibrosis.
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PMID:[Bronchopulmonary dysplasia]. 876 16

Respiratory morbidity, recurrent cough and/or wheeze and lung function abnormalities are common even outside infancy in preschool children born prematurely. Throughout the first 5 years of life, adverse neonatal events such as immaturity at birth and a requirement for prolonged respiratory support are significantly associated with positive symptom status. In the older preschool child, however, there is some evidence to suggest that other factors, such as a family history of atopy, may be equally important. The development of recurrent symptoms even at 4 years of age can be predicted accurately from the results of lung function measurements made in infancy, and hopefully such data will facilitate the introduction of effective intervention strategies. Lung function abnormalities are more marked in symptomatic patients and, in older children, seem to reflect increased airway responsiveness rather than having a significant relationship to adverse neonatal events. The hospital readmission rate for respiratory disorders, however, is certainly adversely affected by extremely low birthweight and neonatal chronic lung disease, as well as current symptom status. These data highlight that strategies to reduce extremely premature delivery and its consequences should favourably influence respiratory morbidity in preschool children.
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PMID:Respiratory morbidity in preschool children born prematurely. Relationship to adverse neonatal events. 881 40

In Japan, chronic lung disease (CLD) is defined as an oxygen requirement greater than that obtainable in room air at 28 days of age, with symptoms of persistent respirator distress and a hazy or emphysematous and fibrous appearance upon chest x-ray. A total of 4964 infants weighing less than 1500 g at birth and born in 1990 were admitted to and cared for at level II and III neonatal care centers in Japan. A total of 4293 infants (86.3%) survived at 28 days after birth. Analyses of infants who developed CLD through their preceding illnesses and chest x-ray findings resulted in the classification of CLD into six types. Types I and II are defined as CLD following the acute stage respiratory distress syndrome (RDS). Type I is the typical case of bronchopulmonary dysplasia (BPD) as described previously, whereas Type II shows atypical radiological findings, namely only diffuse haziness without typical emphysema and fibrosis. Type III has a history of intrauterine inflammation. Chest x-ray shows the typical bubbling and cystic appearance described in the original report of Wilson-Mikity syndrome or neonatal pulmonary emphysema in the very low birth weight infant. Type III also has atypical radiological findings in cases with intrauterine infection. Type IV does not have a history of either intrauterine inflammation or RDS but shows typical emphysematous and fibrous appearance upon chest x-ray. Type V includes those with atypical chest x-ray appearance similar to Type II but without history of RDS and intrauterine inflammation. CLD is a heterogeneous condition which shows different spectra. However, the cardinal event is common to all types--the excessive inflammatory response caused by various insults to the immature airways and alveoli, such as oxygen, barotrauma, infection and so on. The excessive inflammatory response leads to lung tissue damage and the abnormal healing process due to immaturity, (such as vitamin A deficiency and insufficient oxygen radical scavenging system) and results in dysplasia and metaplasia of the respiratory system. The treatment of respiratory distress due to CLD also acts as an insult to the lungs and thus forms a vicious cycle. The different spectra of the disease are most possibly attributed to the difference in the timing and the kind of insults to the lungs. In Type I and II CLD, the insults are given in the first hours of life when the infants with surfactant deficiency receive high concentrations of oxygen for stabilization before the surfactant replacement. In Type III and III' CLD the insults are most likely given before birth. Excessive and sustained inflammatory response in the lungs with different onset times may result in the development of Type IV and V CLD. The strategy for the prevention of CLD should be different according to the origins and causes. The prevention of Type I and II CLD, or CLD following RDS, should be accomplished by successful prophylactic surfactant replacement therapy. Another procedure may be the application of high frequency oscillatory ventilation (HFOV) in the acute stage of RDS or at the time of stabilization right after birth. Types III and III' CLD present the most difficult challenge for prevention strategy because the disease process already started before birth. At the moment there are no effective measures for prevention. The strategy for the prevention of Type IV and V CLD may reside in the early detection and treatment of patent ductus arteriosus, sepsis and airway infection including pneumonia.
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PMID:Chronic lung disease of the very low birth weight infant--is it preventable? 967 27

Drug utilisation in term and preterm neonates (i.e. less than 28 days of age) has been investigated prospectively in 4 clinical studies during the past 10 years. 3880 neonates with a mean gestational age of 34.5 weeks (corresponding birthweight 2280g) were enrolled in these studies. An overview indicates a high prevalence of antibiotic treatment throughout the studies, ranging from 69% to virtually 100%. The highest prevalence was observed in studies enrolling only preterm neonates (gestational age less than 30 weeks) with need for mechanical ventilation. A further high prevalence of parenteral nutrition (84 to 100%), transfusion of blood products (91 to 100%) and vitamin use (16 to 78%) was described. Higher degrees of immaturity and rates of complications were associated with an increased drug usage up to a mean of 17 different drugs in very preterm (i.e. less than or equal to 30 weeks gestation) neonates with severe respiratory disorders and related complications. The high prevalence of antibiotic usage may be explained by the fact that clinical symptoms of neonatal bacterial infections are usually variable, and laboratory tests initially are not highly specific. Respiratory disorders in neonates are often associated with or caused by infections. Nosocomial infections in neonatal intensive care units further prompt administration of antimicrobial agents. Six prospective controlled clinical trials during the past 10 years have investigated treatment with dexamethasone of bronchopulmonary dysplasia, a chronic lung disease secondary to mechanical ventilation of surfactant-deficient lungs in very preterm neonates.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Drug utilisation in preterm and term neonates. 1014 10

Chronic lung disease (CLD) of prematurity remains a substantial problem despite modern perinatal and neonatal care. CLD remains related to gestational age and lung immaturity, although it has become clear that severe initial lung disease is not a prerequisite for CLD to develop. Attempts to prevent CLD to date have not adequately addressed the multifactorial nature of the complex pathophysiology that leads to CLD. Thus, results have been modest at best. Prevention of CLD will require a multifaceted approach with specific interventions and care practices focused on different aspects of the pathway that leads to CLD. This review considers new information related to causation of CLD and the magnitude of the effect of prevention strategies tested to date. This article also advances the hypothesis that CLD is preventable with a global strategy of minimizing inciting events, optimizing management, and specific therapies aimed at intrinsic vulnerabilities.
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PMID:Strategies for prevention of neonatal chronic lung disease. 1115 5

Surfactant proteins A (SP-A) and D (SP-D) are important in the innate host defense against pathogenic microorganisms. A deficit in these proteins in premature infants, either because of immaturity or as a consequence of superimposed chronic lung disease (CLD), could increase their susceptibility to infection. The study reported here examined infection in CLD in the premature newborn baboon, and correlated it with the amounts of SP-A and SP-D in lung tissue and lavage fluid. Two groups of baboons were delivered prematurely, at 125 d gestational age (g.a.), and differed principally in whether they developed naturally acquired pulmonary infections and sepsis. Group I animals were ventilated with clinically appropriate oxygen for 6 d and 14 d without clinical incident. Group II animals were ventilated for 5 to 71 d, but differed from those in Group I in that most developed pulmonary infection and/or sepsis. In Group I animals, tissue pools of both SP-A and SP-D were equal to or exceeded those in adults, and lavage pools of SP-A increased progressively with the time of ventilation to about 35% of adult levels after 14 d. In contrast, most Group II animals had concentrations of lavage SP-A that were less than 20% of that in adult animals. A low concentration of lavage SP-A correlated with the release of interleukin-8, and with a high "infection index" based on histopathology, microbiologic cultures, and clinical indications of sepsis. Our data suggest that the amounts of SP-A and SP-D in lavage fluid are indicators of the risk of infection in the evolution of neonatal CLD. Deficits in the amount of lavage SP-A, even after 60 d of ventilation, may have inhibited the resolution of infection and thereby contributed to the developing injury among our Group II animals.
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PMID:Deficiencies in lung surfactant proteins A and D are associated with lung infection in very premature neonatal baboons. 1117 12

A deficiency in alveolar surfactant due to immaturity of alveolar type II epithelial cells causes respiratory distress syndrome (RDS). In contrast to animals, the fetal maturation of surfactant in human lungs takes place before term, exceptionally large quantities of surfactant accumulating in the amniotic fluid. The antenatal development of surfactant secretion is very variable but corresponds closely to the risk of RDS. The variation in SP-A and SP-B genes, race, sex and perinatal complications influence susceptibility to RDS. Surfactant therapy has improved the prognosis of RDS remarkably. Abnormalities in alveolar or airway surfactant characterize many lung and airway diseases. In the acute respiratory distress syndrome, deficiencies in surfactant components (phospholipids, SP-B, SP-A) are evident, and may be caused by pro-inflammatory cytokines (IL-1, TNF) that decrease surfactant components. The resultant atelectasis localizes the disease, possibly allowing healing (regeneration, increase in surfactant). In the immature fetus, cytokines accelerate the differentiation of surfactant, preventing RDS. After birth, however, persistent inflammation is associated with low SP-A and chronic lung disease. A future challenge is to understand how to inhibit or redirect the inflammatory response from tissue destruction and poor growth towards normal lung development and regeneration.
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PMID:Surfactant in respiratory distress syndrome and lung injury. 1136 52


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