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

Response of the fetal kidney to metabolic acidosis was studied in five fetal lambs, 115-125 days gestation, in order to evaluate the renal contribution to elimination of hydrogen ion during intra-uterine development. Experiments were conducted on healthy unanesthetized fetuses, intact in utero, with catheters implanted at hysterotomy into a fetal femoral artery and vein and into the bladder via the urachus, four or more days prior to the study. A metabolic acidosis was induced by infusion of isotonic lactic acid, 15 m mole/kg, intravenously over a period of 90 minutes. Serial arterial samples were taken and urine collected in fractions before, during and for three hours following the infusion, for measurements of pH, bicarbonate, lactate and electrolytes as well as urine output. During the infusion, urine pH fell from 6.65 to 6.25 and was 6.34 three hours later (Figs. 1 to 4, Tabs. III to IV). Lactic acid infusion caused a prompt increase in urine output from a mean rate of 0.12 to a maximum of 0.28 ml/kg/min at the end of the infusion, returning to control rates three hours later. Lactate excretion increased from 0.05 to a maximum of 4.6 mumole/kg/min at the end of infusion; titratable acid increased from 0.22 to a maximum of 4 muEq/kg/min; the rates of excretion of lactate and titratable acid were still higher than control at the end of three hours. Ammonia excretion increased from 0.21 to a maximum of 0.56 muEq/kg/min three hours after the end of infusion. The acid infusion caused a small but significant fall in excretion of bicarbonate. During the 90 minutes of infusion and over the following three hours, about 800 mumole lactate was excreted while net acid excretion over the same period was no more than half that amount. The diuresis was also accompanied by a net loss of sodium and chloride, the excretion of these ions increasing more than threefold following acid infusion; excretion of potassium decreased to one-third its rate prior to the infusion. During the 90 minutes of infusion, blood pH fell from 7.36 to 7.13, base deficit rose from 3.8 to 16.4 mEq/L and lactate rose from 2.2 to 14.8 mM/L; there was also a small but significant rise in both blood PCO2 and PO2 (Figs. 1 to 2, Tabs. I to II). During the following three hours of recovery, pH rose gradually to 7.29, base deficit and lactate fell to 7.4 mEq/L and 8.7 mM/L respectively. Since renal excretion of net acid and lactate was small, the decrease in blood base deficit and lactate levels during the recovery must therefore be mainly due to equilibration in various fetal compartments as well as placental transfer. These experiments indicate that, in the lamb fetus, intact in utero, the kidney although limited by immaturity of several mechanisms, is capable of responding to an acid load and thus can make a small contribution to fetal homeostasis. The increase in excretion of net acid is accompanied by loss of sodium and chloride in the urine.
 ...
PMID:Renal response to acid loading in the developing lamb fetus, intact in utero. 0 Apr 79

Based on own studies with labeled amino acids on very young animals and on numerous investigations of different authors on fetuses and prematures the high turnover rate of proteins, carbohydrates and fats in VLBW is emphasized. Thereupon some particularities of ammonia metabolism and the difficulties of exact determination of amino acid requirement are discussed. The inadequate activity of some enzymes and the immaturity of the transport processes, further, the question of the essentiality of taurine and carnitine in VLBW are debated. Briefly some dangers which result from the immaturity of the bowel mucosa are pointed out. The knowledge of the fat metabolism in VLBW has still many gaps. Beyond all doubts the unsaturated fatty acids play an decisive role for the synthesis of prostaglandins and the other derivatives, which are synthesized by the cyclooxygenases in all tissues, especially in brain. Probably the linoleic acid is an essential fatty acid for prematures. The influence of kidney immaturity on the metabolic processes in the entire organism is shortly outlined. Finally some references to the scarcely investigated field of the maturation of the biotransformation are presented, and the risky influence of some repeatedly used drugs on the intermediary metabolism and the inhibition of enzyme induction are pointed out.
 ...
PMID:[Peculiarities of intermediary metabolism in extremely premature infants]. 374 37

Serial blood ammonia (NH3) determinations in 19 low birth weight (LBW) infants, 14 term neonates and 12 children receiving total parenteral nutrition (TPN) have shown that 73% of patients had one or more elevated NH3 values (greater than 150 micrograms/dl). The mean blood NH3 was 220 +/- 13 micrograms/dl in LBW infants, 180 +/- 9 micrograms/dl in 10 infants, and 140 +/- 7 micrograms/dl in children. All of these values are significantly higher than normal (p less than 0.001). There was no difference in incidence or mean blood ammonia concentration between patients receiving casein hydrolysate and those receiving a crystalline amino acid solution. Only four patients were symptomatic and several infants remained fully alert despite blood NH3 concentration in excess of 400 micrograms/dl. One infant who had sustained hyperammonemia was given another amino acid source (Travasol) containing 1.2 mmol/dl of arginine; blood NH3 promptly fell to the normal range. However, six of seven additional infants had hyperammonemia while receiving Travasol (mean = 184 micrograms/dl). Hyperammonemia is common during TPN in children, often is not recognized clinically, and occurs with equal frequency in infants and older children. The high levels observed in LBW infants may be due to hepatic immaturity. Blood NH3 concentration should be monitored frequently during TPN. Persistent hyperammonemia should be treated by decreasing protein content of the infusate. The role of supplemental arginine is unclear.
 ...
PMID:Hyperammonemia during total parenteral nutrition in children. 680 70

Latex is a substance that is extracted from the plant Hevea Brasiliensis, and world production is 6 million metric tons per year. After gathering it undergoes a series of processes in which ammonia, vulcanization-accelerating additives or anti-oxidants are added. All of this may constitute the antigenic load that latex contains. It is used in medicine for gloves, drainage tubes, dental implants and a growing number of products from condoms to sport products or automobile components. Over fifteen different allergenic bands have been described, with molecular weights of between 2 and 100 kDa. In a joint study, USA-Finland identified three antigenic bands that predominate according to the population type studied (2). In children with spina bifida, congenital urogenital abnormalities or those submitted to multiple surgical interventions, the band of 27 kDa is predominant. This antigen has not been detected in adult serum, which suggests that contact with the antigen is through the mucous membranes and the sensitization is triggered from here. The incidence of allergy to latex in the general population is not known, but it seems to be lower than 1%. Turjanmaa (1) establishes a frequency of 0.125% (1/800) in patients submitted to general surgery. The incidence of sensitization to latex varies according to the population studied. Among the population considered to be at risk are the workers of the health environment, where the incidence is between 2.6 and 16.9%, whereas in the general population the percentage is around 1%. Sensitivity to latex is of great importance in patients suffering from spina bifida, in whom an incidence of between 28 and 67% has been found. We present our experience in a group of children attending our service for the first time for diverse reasons of supposed allergic etiology. The objective is to determine the incidence of sensitization to latex according to the diagnostic methodology [cutaneous test or by determination of specific IgE (CAP)]; according to the type of patient (atopic or non-atopic), the direct relationship with latex material and the role that can be played by a history of surgical intervention. In our experience with 282 children studied in our pediatric allergology service using diverse methods, the incidence of allergy to latex is 3.19%. Nevertheless, if we analyze this percentage we observe that if the diagnosis is based exclusively on cutaneous tests, it is only 1.08%; if to establish a diagnosis we used exclusively the determination of specific IgE (CAP) we would label 7. 2% of our children as allergic. Atopy is a factor that facilitates sensitization. In our sample, the incidence among the atopic population is 4.4%, though this percentage may vary between 1.69% and 9.5% depending on the methodology used. There are several hypotheses for explaining these discrepancies in the diagnostic tests. Although there do not seem to be differences regarding the ammonia content of the different lots, it seems that the differential factor could lie in the type of extract and in whether it is commercial or a natural latex extract. It could be a consequence of the existence of a prophyllin, so it has not been ruled out that a part of the IgE is an antiprophyllin. The presence of different epitopes would mean that each of them has the ability to produce its own specific IgE, though the RAST/CAP was not able to differentiate them and identified them as whole. The rate of allergy to latex in a group of children suffering from myelomeningocele is 80%. At a paediatric level, sensitization to latex is influenced by the means of contact, the duration of the exposure to the antigen and the fact that the exposure occurs early, which in the case of children with myelomeningocele is associated with the immaturity of the defence mechanism of the mucous membranes.
 ...
PMID:Prevalence of allergy to latex in the pediatric population. 1043 Oct 98

Hyperammonemia of newborns should be treated promptly, and the outcome depends on the rapid elimination of excessive plasma ammonia. We encountered a case of transient hyperammonemia in an extremely low-birthweight infant whose plasma ammonia decreased sufficiently after continuous hemodialysis therapy. It seems that continuous hemodialysis therapy using the peripheral artery and umbilical vein is useful for hyperammonemia of extremely low-birthweight infants; however, there are several problems to consider due to the immaturity of these infants.
...
PMID:Continuous hemodialysis therapy for an extremely low-birthweight infant with hyperammonemia. 2413 57