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

When compared to adults, muscle mass in children is lower and the relative development of aerobic and anaerobic pathways is different. The main consequences are the following: 1) The aerobic metabolism, evaluated by measurement of maximal oxygen uptake (VO2max), is either the same as in adults or more developed when VO2 max is related to body mass or lean body mass. 2) The maximal anaerobic power developed during force-velocity test and Wingate test is lower than in adults even if it is expressed by total or lean body mass unit. Blood lactate concentration is also lower. This immaturity of the anaerobic metabolism, especially the "lactic pathway" may result from lower anaerobic enzyme activities (lactico-dehydrogenase, phosphofructokinase, etc) and glycogen content. During puberty, "lactic metabolism" starts to develop significantly, simultaneously with muscle mass. It has been suggested that sexual hormones (testosterone in boys, oestrogens in girls) and other factors, such as growth factors, are implicated in this phenomenon. During this period, the aerobic metabolism remains unchanged. In prepubertal children there is neither aerobic nor anaerobic specialization: the highest anaerobic performance is associated with the highest VO2 max. Moreover, it seems that before puberty, bioenergetic profile is not modified by training. 3) Despite a high VO2 max, performance in endurance events is not as high in children as in adults because of a lower running economy. Cardiovascular responses are characterized by higher maximal and infra-maximal heart rates, and lower systolic stroke volume and arterial blood pressures than in adults. During prolonged exercise, the hormonal adaptations for energy substrate utilization is quite different from adults: a lower decrease in insulin and increase in catecholamines and glucagon in response to exercise could be responsible for a less effective regulation of glycemia with a risk of hypoglycemia. Therefore, an adequate carbohydrate intake is recommended.
Arch Pediatr 1994 Sep
PMID:[Physiology of muscular exercise in children]. 784 28

Although it is well known fact that patients with Lowe syndrome have a delay in developmental milestones, muscle hypotonia and weakness, no detailed pathologic study to explain the muscle symptoms is available. In two patients with Lowe syndrome aged 22 years and 14 years, respectively, the biopsied biceps brachii muscles showed no significant morphologic changes except for small caliber fibers measuring almost 1/3 of the normal size. Although the muscle fiber type distribution is normal with no increase in undifferentiated type 2 C fibers, there remains a possibility of a certain defective neural influence on developing muscle fibers or metabolic defect. The muscle fiber immaturity is probably responsible for muscle weakness and hypotonia in this syndrome.
No To Hattatsu 1994 Sep
PMID:[Muscle fiber involvement in Lowe syndrome]. 791 93

We examined 48 placentas of human immunodeficiency virus (HIV)-exposed pregnancies morphologically for HIV-specific changes and immunohistologically for the presence of HIV antigen and RNA. Findings were correlated to infectious states of the children and maternal risk factors. Few HIV antigen-positive Hofbauer cells and HIV RNA positive syncytiotrophoblast and Hofbauer cells were detected. HIV-positive cells in the placenta did not correlate with intrauterine infection and maternal immunologic parameters. Light microscopically, we found two changes: immaturity of the terminal villi and allantois vasculopathy. These changes, however, are not HIV specific. Our results show that vertical HIV transmission cannot be diagnosed by morphological examination of the placenta.
Am J Perinatol 1994 Sep
PMID:Vertical human immunodeficiency virus transmission: a study of placental pathology in relation to maternal risk factors. 799 9

In order to determine whether less skeletally mature adolescents experience more complications during pregnancy and give birth to smaller, less mature infants than do more skeletally mature adolescents, data were collected from the Rochester Study of Adolescent Pregnancy, a 3-year prospective study. The sample included 114 consecutively enrolled, low-income, Black, adolescents who were 12-18 years old at conception and 19 years old at delivery. In the subset examined (n=93), maternal age was determined according to chronological age, gynecologic age, and postpartum bone age from a roentgenogram of the left hand and wrist taken during the puerperium. As a categorical variable, bone age was dichotomized as 18 (immature) and 18 years (mature). Maternal body size at conception was determined by prepregnant weight, height at enrollment, and prepregnant body-mass index (weight/height sq.). Maternal weight gain was the difference between the last weight determination prior to delivery and prepregnant weight. Maternal growth was determined by the difference in prepregnant height and a second height measurement made during the puerperium on 52 (56%) of the subjects. Statistical analyses was performed with the Statistical Package for the Social Sciences. It was found that maternal bone age correlated positively with chronologic and gynecologic age. Maternal bone age also correlated positively with maternal prepregnant weight and body-mass index, but the 64 skeletally immature subjects were not significantly smaller than the 29 skeletally mature subjects at conception. Maternal bone age did not correlate with total maternal weight gain or with maternal growth in stature during pregnancy, but the 64 less skeletally mature subjects gained weight more rapidly in the second and third trimesters than did the 29 skeletally mature study subjects, although the skeletally immature grew less in stature. Obstetric complications and neonatal outcomes were not related to maternal bone age. These findings should not be considered proof of a lack of physiologic risk associated with early adolescent childbearing. The population studied may have been atypical (the infants born to adolescents 16 years old were not smaller than those born to older adolescents), the sample may have been too small to reveal statistical differences, and bone age is only a proxy indicator of physiologic and reproductive maturity. Further studies, which would include successfully completed pregnancies and conceptions which resulted in miscarriage or fetal death, are necessary to elucidate the effects of reproductive immaturity on the outcomes of adolescent pregnancy.
J Adolesc Health 1993 Sep
PMID:Skeletal maturity and growth of adolescent mothers: relationship to pregnancy outcome. 794 48

Renal immaturity is pronounced in very low-birth-weight infants with a gestational age < or = 30 weeks. We attempted to elucidate if conditions requiring mechanical ventilation, including patent ductus arteriosus, might further compromise renal function due to decreased renal perfusion. Forty infants studied between 4 and 28 days of age were divided into four groups: Control with no patent ductus or mechanical ventilation (n = 8); PDA+MV, with both patent ductus and mechanical ventilation (n = 17); PDA, with patent ductus (n = 6); MV, with mechanical ventilation (n = 9). The groups PDA+MV and MV had significantly lower creatinine clearances and significantly higher fractional sodium excretions than controls. Mean arterial pressure was significantly lower in all groups compared to controls and correlated significantly with creatinine clearance (r = 0.47, p < 0.02). In conclusion, low renal function in these infants is further compromised by a patent ductus arteriosus and/or the use of mechanical ventilation.
Acta Paediatr 1993 Sep
PMID:Renal function in sick, very low-birth-weight infants. 824 64

The aim of the present study is to examine whether the formation of the cranial and cervical flexures is involved in the process of cardiac looping, and whether looping anomalies are causally involved in the development of cardiac malformations. For this purpose, the formation of the cranial and cervical flexures was experimentally suppressed in chick embryos by introducing a straight human hair into the neural tube. In the experimental embryos, the absence of the cervical flexure, alone or in combination with a reduced cranial flexure, was always associated with anomalies in the looping of the tubular heart. The convergence of the primary distant venous and arterial ends of the heart, as well as the normal movement of the ventricular region from its original position, cranial and ventral from the cardiac inflow, to its final position caudal to the presumptive atria, was suppressed to an extent related to the degree to which the formation of the flexures was prevented. Positional immaturity of the heart loop (increased distance between its inflow and outflow, and cranio-ventral position of the ventricular region) was associated with incomplete deformations (reduced angulations) of the cardiac wall at the atrioventricular or conoventricular junctional areas. Reduced angulations were associated with the hypoplasia of the anlagen of the cardiac septa at the level of the angulation (av-cushions, conal ridges). Hypoplasia of these anlagen was followed by incomplete or absent fusion of their opposite free edges, which finally resulted in atrioventricular or ventricular septal defects. These results show that the convergence of the venous and arterial ends of the tubular heart and the caudo-dorsal movement of its ventricular region are related to the formation of the cervical flexure, and that the mesenchymal septa of the heart seem to develop in response to deformations of the embryonic heart, which are generated by the process of cardiac looping. Therefore, the positional and morphological changes of the looping heart are regarded as playing a key role in the process of normal and abnormal morphogenesis of the heart.
Anat Embryol (Berl) 1993 Sep
PMID:Correlation between the embryonic head flexures and cardiac development. An experimental study in chick embryos. 825 Feb 82

The preterm birth of immature triplets before 28 weeks is associated with excess morbidity and mortality risks attributable to extreme immaturity. We report a case of fraternal triplets in preterm labor in which the second and third triplet births were delayed 11 days after the first birth, at 26 4/7 weeks' gestation. The later-born sibs were heavier at birth and throughout their neonatal course in the hospital and suffered less severe complications as compared to the first-born triplet. Delayed birth intervals of triplets in preterm labor should be considered to improve perinatal salvage of immature triplets, although a successful outcome is rare and unexpected.
J Reprod Med 1993 Sep
PMID:Delayed birth intervals of immature fraternal triplets in preterm labor. A case report. 825 99

The frequencies of 10 diseases in a cadmium (and zinc) contaminated region in The Netherlands were analysed by comparing hospital admissions with those of a non-contaminated region and with national values. No significant differences were found for diseases which are commonly associated with increased cadmium uptake such as renal insufficiency, nephrolithiasis, hypertension, cancer, immaturity of the new-born. For the contaminated region a significantly higher frequency was only found for atherosclerosis; this was relatively strong for men aged > 40 yrs. However, no higher death frequency for atherosclerosis was observed. The results are discussed in relation to limitations in the evaluation techniques used. The absence of major health risks in the contaminated area is obvious, but the possible influence of long term-low level cadmium uptake on atherosclerosis requires more attention.
Sci Total Environ 1993 Sep 30
PMID:Prolonged low-level cadmium intake and atherosclerosis. 825 93

Adult white Leghorn chickens exhibited a sexual dimorphism in hepatic microsomal monooxygenases determined from the concentrations of total cytochromes P450 and b5, and the metabolism of drug (hexobarbital, coumarin and ethoxyresorufin) and steroid (androstenedione and testosterone) substrates that were 2- to 4-fold greater in roosters than in hens. Caponizing at 6 weeks of age reduced the activities of the monooxygenases to levels comparable to those found in intact hens. In spite of the fact that testosterone replacement maximally stimulated comb growth in the capons and elevated (i.e. masculinized) hepatic monooxygenase activities in the hens to male-like levels, androgen replacement was ineffective in increasing the subnormal enzyme levels in the capons. While the failure of testosterone administration to restore monooxygenase levels in the capons may be explained by the immaturity of the birds at orchiectomy, the present results demonstrate, that like some mammals, birds may display gender differences in hepatic monooxygenases that are regulated by the testes.
Biochem Pharmacol 1993 Sep 01
PMID:Sexual dimorphism in avian hepatic monooxygenases. 837 39

The importance of the EEG for the investigation of neurological diseases in the neonatal period has been largely discussed, since it is often the only way to approach cerebral function in newborns with severe pathologies or under drug effect. The present study was carried out with 85 newborns (NB) who presented perinatal dysfunctions and were submitted to neurological and electroencephalogram (EEG) or polysomnography (PS) evaluation. EEG/PS alterations, pathologies and prognosis were reported. The EEG were classified according to basal activity alterations, presence of paroxysmal activity and sleep stages organization and maturity. The most frequent pathology was perinatal asphyxia (40%) followed by intraventricular hemorrhage (HIV, 16%). The most frequent complaint for exam indication was apnea (71%) followed by convulsion (19%). Fifty-five percent of the exams exclusively required because apnea complaint were considered normal and out of all exams required because seizures only 31% were normal. The EEG alteration most frequently related to perinatal asphyxia, HIV and intrauterine growth delay was immaturity and in the NB with seizures immature EEG and abnormal paroxysms. Many different alterations were registered in the NB with nervous system infection. The EEG findings more correlated with unfavorable prognosis were isoelectricity and abnormal paroxysmal activity including positive sharp waves (100%).
Arq Neuropsiquiatr 1995 Sep
PMID:[Value of EEG in the characterization and prognosis of neurological diseases in premature infants]. 858 21


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