Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0029713 (immaturity)
 4,335 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Examinations were made with the use of same materials as in Part I and according to the same methodology. The great capability of the calves kidneys to economise water was observed. The kidneys are able already in the second week of calves life to reduce and increase urine concentration within limits from 65.70 to 955.54 mmol/kg H2O, keeping at the same time molality of the body fluids on relatively the same level. It may prove high efficiency of the hypothalamic pituitary antidiuretic system. It seems, that because of the probable immaturity of tubules it was difficult to create the high osmotic gradient in the renal medulla what is confirmed by the changing clearances of the free water and the resorption water. It also seems, that the rate with which urine is passing through the renal tubules is of great importance in the process of thickening the urine in this period.
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PMID:[Kidney function in calves in the neonatal period. II. Studies of the capacity to reduce and increase urine concentration]. 248 68

To examine the effect of a patent ductus arteriosus on water accumulation and protein permeability in the premature, ventilated lung, we studied 16 lambs at 121-127 d gestation (term = 145 d). Water accumulation was assessed by the wet:dry wt ratio of the blood-free left lung. Protein permeability was assessed by the albumin content and by the recovery of 125I-albumin in the right lung lavage fluid 1 h after intravenous injection. Using a model that allows mechanical control of ductus patency, we compared nine lambs with patent ductus (left-to-right shunts 42 +/- 18% to left ventricular output) with seven lambs with closed ductus. The animals were studied over 3 h. In the open ductus lambs, 0.85 +/- 0.36 and 1.76 +/- 1.87%/h of the injected 125I-albumin was recovered in the lavage fluid and lung tissue, respectively. In the closed ductus lambs, the corresponding amounts were 0.71 +/- 0.21 and 0.71 +/- 0.22%/h; these differences were not statistically significant. Similarly, blood-free wet:dry ratios did not differ significantly between the two groups (7.01 +/- 1.28 open ductus versus 6.55 +/- 0.82 closed ductus). We concluded that patency of the ductus arteriosus does not significantly affect water accumulation and net protein transudation into the airways of preterm lambs in the first hours of life. Therefore, some other feature of immaturity must be responsible for the large protein leaks previously observed by others.
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PMID:Effect of patent ductus arteriosus on water accumulation and protein permeability in the lungs of mechanically ventilated premature lambs. 260 36

After having been virtually completely forgotten since the Second World War, paediatric regional anaesthesia has been undergoing a renewal in the last decade. This renewed interest in old techniques is due to several converging factors: a better knowledge of the pharmacology of local anaesthetic agents in the child, the availability of equipment adapted for children, the remarkable haemodynamic stability of the very young child during an epidural block, as well as the need to treat pain not just in the operative period. The child is not, or rather, is not only a small adult. Embryological development is not finished at birth. The incompletely myelinized nervous system as well as the incomplete skeletal ossification will influence local anaesthetic pharmacodynamics and the choice of anaesthetic technique and anatomical landmarks. Aponeurotic sheaths are only poorly attached to anatomical structures, especially nerves. This, together with the fact that epidural fat in the young child is very fluid, explains why some techniques are very efficient, but also why the volumes of required anaesthetic solution are proportionately much more important than in adults. The general pharmacology of local anaesthetic drugs is very close to adults. However, the very important regional blood flow rates, the different body water distribution, the immature neurovegetative system, the weak activity of some enzymes, and the relatively greater importance of the liver and brain by weight explain the differences found in pharmacokinetics, which are differences in degree and not in nature. The choice of the appropriate local anaesthetic agent depends on these factors. In France, the chosen drug will almost exclusively be an amide, mostly lignocaine and bupivacaine. The psychological immaturity of children makes any assessment of pain quite difficult. Moreover, body image has not yet been completely acquired in most cases, so reducing the possibility of conceptualization. The usefulness of techniques requiring an active patient participation, in particular the search for paraesthesia, is therefore rather reduced. Light general anaesthesia and peripheral nerve stimulators (for nerve blocks) are essential, and desirable at least, if not wished by most patients. Caudal anaesthesia is an important technique in the child. It is easy to perform, efficient, with small risk. Its ideal indication is surgery below the umbilicus in the infant and young child. Lumbar epidural anaesthesia requires greater experience as well as proper equipment, especially in the very young child. Peripheral nerve blocks are less used than in adults.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Regional anesthesia in pediatrics]. 265 20

Renal function in the newborn infant varies with conceptual age and should be evaluated in this context. Very preterm infants less than 34 weeks' conceptual age have reduced GFR and tubular immaturity in the handling of filtered solutes when compared to term infants. Premature infants between 34 and 37 weeks' conceptual age undergo rapid maturation of renal function similar to term infants, with establishment of glomerulotubular balance early in the postnatal period. ARF in neonates differs from that seen in older children and adults in that ischemic (e.g., hypoxic) insults and congenital malformations constitute the major pathophysiologic mechanisms responsible for clinically observed oliguria and azotemia. Principles of conservative management are similar to those used in older children except for the greatly increased insensible water loss requirements of the very preterm and premature infant. Technical advances have added peritoneal dialysis and CAVH to the therapeutic regimen for persistent ARF or life-threatening complications of reduced renal function.
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PMID:Renal function and renal failure in the newborn. 265 61

Many centrally acting drugs which are prescribed for hypertension, depression, epilepsy, insomnia and asthma may also affect fetal brain neurotransmission and behavioral states. Nearly all these drugs enter the fetal circulation following maternal administration. The immaturity of the blood-brain barrier and greater accumulation in the developing brain make the fetal brain a major target of its mother's medication. Adverse effects that are seen in the fetus are not necessarily evident in its mother. We have shown that drugs like clonidine (an antihypertensive) and clomipramine (an antidepressant), which act on noradrenaline and serotonin neurotransmission in the brain, suppress rapid eye movement sleep in the developing rat. In adulthood, the neonatally treated rats showed hyperactivity, hyperanxiety, reduced sexual behavior, disturbed sleep patterns and reduced cerebral cortical size. Furthermore, such treatment induced an increase in voluntary alcohol consumption and a decreased adaptability of responses to changes in water deprivation in a Y-maze. Little is known about long-lasting consequences of centrally acting drugs used during late gestation in humans. Minor neurological disturbances, such as delayed visual motor performance, smaller head circumference, increased anxiety and disturbed sleep-wake patterns, have been reported in children born to hypertensive mothers treated with clonidine or alpha-methyl-dopa.
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PMID:Neurochemical and electrophysiological disturbances mediate developmental behavioral alterations produced by medicines. 287 4

The present studies were undertaken to determine, by recollection micropuncture, the effect of a synthetic atrial natriuretic peptide (ANP) on the absolute and fractional deliveries of water and sodium to the juxtamedullary end-descending limb. Two groups of young female Munich-Wistar rats were studied: control (n = 8) received the vehicle only; and ANP (n = 12) received a prime followed by the constant infusion of a synthetic rat atrial peptide (28 amino acids). With the infusion of ANP, clearance of p-[14C]aminohippurate [( 14C]PAH) and glomerular filtration rate (GFR) fell significantly. Despite this fall in GFR and renal plasma flow, ANP produced a 2-fold increase in urine volume and a 10-fold increase in sodium excretion. Absolute and fractional sodium deliveries to the end-descending limb increased by approximately 30% in the ANP group, whereas mean juxtamedullary single-nephron glomerular filtration rate (SNGFR) remained stable. In three additional rats prepared for micropuncture of the superficial end-accessible proximal tubule, ANP reduced cortical SNGFR by approximately 15%. By contrast, GFR did not decline in response to ANP in larger rats, when treated identically. We conclude that in young rats ANP can produce a natriuresis in the absence of a rise in GFR; the fall in GFR observed following ANP is due presumably to the immaturity of the animals used in these studies; and ANP produces a rise in absolute and fractional water and sodium deliveries to the end-descending limb that cannot be attributed to a change in SNGFR.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of synthetic ANP on renal and loop of Henle functions in the young rat. 294 65

Rational pharmacotherapy is dependent upon an understanding of the clinical pharmacokinetic and pharmacodynamic properties of the drugs employed. Although the available data on drug biodisposition and action in the neonate have increased considerably in the last few years, pharmacokinetic-pharmacodynamic interactions for many drugs remain poorly understood. The ontogeny of drug absorption, distribution, metabolism, and elimination are addressed in this review. Drug absorption from any site depends upon both the physicochemical properties of the drug and a variety of patient factors. Absorption of orally administered drugs may be affected by changes in gastric acidity and emptying time as well as by bile salt pool size, bacterial colonisation, and extraintestinal disease states such as congestive heart failure. Factors affecting drug absorption following intramuscular, percutaneous, and rectal administration are also discussed. Drug distribution in the neonate is influenced by a variety of important and predictable age-dependent factors. The developmental aspects of protein binding and body water compartments are described. Additionally, hepatic drug metabolism assumes an important role in understanding the pharmacokinetic and pharmacodynamic properties of many compounds. Certain biotransformation pathways, including hydroxylation by the P450 mono-oxygenase system and glucuronidation, demonstrate only limited activity at birth, while other pathways, such as sulphate or glycine conjugation, appear very efficient at birth. Elimination of drugs excreted unchanged in the urine is dramatically reduced in the newborn, compared with older infants and children, due to immaturity of both glomerular filtration and tubular secretory processes. The glomerular filtration rate remains markedly reduced prior to 34 weeks gestational age, increasing as a function of post-conceptual age until adult values are achieved by approximately 2.5 to 5 months of age. Tubular secretory capacity is also limited at birth, approaching adult values by approximately 7 months of age. Published reports describing the pharmacokinetics and pharmacodynamics of commonly used drugs in the neonatal period, as well as differences in drug biodisposition among premature infants, full term neonates, and older infants and children, are reviewed. Our recommendations for neonatal drug therapy are based upon a critical interpretation of these data, an understanding of fetal development and maturational processes, and an understanding of how disease states may affect drug biodisposition in the neonate.
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PMID:Principles of drug biodisposition in the neonate. A critical evaluation of the pharmacokinetic-pharmacodynamic interface (Part I). 329

The clinical response and changes in water and salt homeostasis during ORT was studied in 15 infants less than 2 months old (range 2-50 days) with acute diarrhoea. Eight patients were neonates and 7 were 1-2 months old. The oral rehydration solution contained 60 mmol sodium per litre. All patients except one were successfully rehydrated. The fluid retention was significantly higher in neonates and young infants than in infants above 3 months of age treated in the same way. One patient in the group of neonates who had a normal sodium level on admission developed hypernatremia with a sodium level of 162 mmol/l 36 hours after the start of ORT. The urinary sodium excretion was lower in the neonates than in the young infants. The results show that neonates and young infants have a lower capacity than older infants to excrete water and salt and therefore run a great risk of developing fluid and salt retention during ORT. The risk is most pronounced in neonates who, due to immaturity of the renal function, are unable to excrete excess fluid and salt.
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PMID:Oral rehydration therapy in neonates and young infants with infectious diarrhoea. 330 Jan 47

Vitamins are organic compounds essential in small amounts for metabolic functions. Since they cannot be synthesized in the body they must be supplied with the diet. While fat-soluble vitamins cross the placenta by single and/or facilitated diffusion the water-soluble vitamins are actively transported with the exception of vitamin C. An adequate supply of fat-soluble vitamins to the fetus seems to be dependent on maternal blood levels during gestation. On the contrary, the transfer of water-soluble vitamins is relatively independent of the levels in maternal blood. Due to their immaturity preterm and low birth weight infants require higher dosages of some vitamins compared to healthy full-term newborns.
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PMID:Vitamins and the premature. 332 38

This one-dimensional thin-layer chromatographic method is used for assay of phospholipids in the gastric aspirate of newborns. The solvent mixture (chloroform/hexane/methanol/glacial acetic acid/water, 12/7/4/3/0.3 by vol) completely resolves lecithin, sphingomyelin, phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine, and phosphatidylglycerol. The method is simple, precise, inexpensive, and rapid (chromatographic development takes less than 25 min) and gives high chromatographic resolution. We used this method to determine the lecithin/sphingomyelin densitometric ratio (L/S ratio) and the phosphatidylglycerol percentage in 200 samples of gastric aspirate and found an L/S ratio of 2.5 to be a satisfactory cutoff value for distinguishing fetal lung maturity and immaturity. We confirmed that the presence of phosphatidylglycerol excluded the possibility of respiratory distress.
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PMID:Improved thin-layer chromatographic determination of phospholipids in gastric aspirate from newborns, for assessment of lung maturity. 335 10


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