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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.
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PMID:Renal response to acid loading in the developing lamb fetus, intact in utero. 0 Apr 79

The distribution of sodium- and potassium-stimulated ATPase (Na,K-ATPase) along the crypt-villus axis and crypt cytokinetics were examined in an infective model of celiac disease produced by infection of the rat with the nematode Nippostrongylus brasiliensis. In controls, levels of enzyme activity remained stable during enterocyte migration to the villous apex. In the jejunum of infected rats, the structural lesion of villous atrophy and crypt hyperplasia, observed at day 10 of infection, was associated with a three-dimensional expansion of the crypts. Cell cycle time was shortened and this resulted in a markedly increased crypt cell production rate. Enterocytes emerged from the crypts at a faster rate, and this functional immaturity was paralleled by decreased Na,K-ATPase activity. Further decreases in enzyme levels were observed during enterocyte migration along the villi. This may reflect enterocyte damage or increased enzyme turnover. In the ileum of these animals, enterocyte maturation was prolonged and enzyme activity was increased at the level of the crypt villus junction with further increases noted during enterocyte transit. These changes in ileal Na,K-ATPase appear to be adaptive.
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PMID:Alterations in quantitative distribution of Na,K-ATPase activity along crypt-villus axis in animal model of malabsorption characterized by hyperproliferative crypt cytokinetics. 131 Apr 59

We studied urine excretion of free and conjugated aldosterone by 12 control infants and 14 infants with hyaline membrane disease (HMD) on the first and seventh days after birth. Both groups had a mean gestational age of 29 weeks. Total urine aldosterone excretion (UAE) and percent excreted as conjugate were similar for both groups on both study days, and did not relate to the severity of respiratory failure in infants with HMD. Sodium intake was higher for infants with HMD on both study days (p less than 0.02), but their urine sodium excretion was only significantly (p less than 0.01) higher on day 7. For total UAE values greater than 3 nmol/kg/d, there was no significant difference between estimated sodium-potassium exchange by control (22 +/- 5%, n = 8) and HMD (31 +/- 5%, n = 10) groups. These data suggest that neither the magnitude of excretion of aldosterone in the urine, the ability to conjugate aldosterone nor the degree of relative distal tubular unresponsiveness to aldosterone are related to the severity of pulmonary immaturity in preterm infants.
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PMID:Hyaline membrane disease and early neonatal aldosterone metabolism in infants of less than 33 weeks gestation. 186 79

In spite of the successful results of fetal reduction, the author's express concern that the practice not become a part of reproduction management, but as a practice to help infertile couples and prevent the unwanted effects of multiple pregnancies. Since 1977 there has been the ability to promote fertility through use of drugs such as clomiphene citrate and personal and in vitro fertilization with the consequence in multiple embryos. The risks to the mother may be pre-eclampsia, post partum hemorrhage, and thrombophlebitis, and/or fetal pre-maturity, immaturity, and perinatal morbidity and mortality. SInce 1986 fetal reduction techniques have been available. This imposes ethical difficulties. The authors report the results of 22 Belgian patients, who carried 87 fetuses between 1985 and 1989, and received multiple pregnancy reduction (MPR). Of these, 4 are still pregnant at 32 weeks, 4 were lost completely and 1 lost in utero, and 33 live births. The live birth rate was 82% with mild morbidity. 78% were low birth weights including 2 under 1000 grams, but with no losses. It appears from the available evidence that the 15% lost is comparable. The procedure, which is described, was changes from transcervical aspiration to intra thoracic KC1 (potassium chloride) injection due to concern for vaginal bacterial growth, and the safe affects on the remaining fetuses. Complication during pregnancy included three patients with pre- eclampsia, but delivered successfully, and 1 with a Shirodkar cerclage at 20 weeks and with ruptured membranes at 37 weeks, but delivered successfully, and 1 preterm labor at 22 weeks who delivered successfully after 28 weeks with 1 dying in utero. She has been infused with beta- mimetics and maintained on indomethacin in the Trendelenburg position.
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PMID:Multifetal pregnancy reduction: a Belgian experience. 200 43

The studies outlined in this review suggest that the immaturity of distal nephron segments may hinder urinary excretion of potassium early in life. Among the factors that may limit potassium secretion by principal cells in the neonatal cortical collecting duct are an unfavorable electrochemical gradient (reduced Ki, Na(+)-K(+)-ATPase activity and/or Vte), limited membrane permeability to potassium and sodium, low tubular fluid flow rate, reduced luminal sodium concentration, or increased paracellular backleak. Alternatively, enhanced potassium absorption by other relatively well-differentiated distal nephron segments may contribute in part to a reduced net potassium excretory rate in the newborn. It should be kept in mind, however, that the limited potassium secretory capacity of the immature kidney becomes clinically relevant only under conditions of potassium excess. Under normal circumstances, the tendency of the newborn to retain potassium is an appropriate and necessary condition for growth.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Maturation of renal potassium transport. 203 47

Clearance experiments concerning the influence of hypophysin + (0.1 vol. unit/kg) and desoxycorticosterone-21-acetate (0.1 mg/kg) on sodium, potassium, calcium, magnesium and inorganic phosphorus excretion in urine have been carried out on 12 bulls at the age of 2-5 weeks of life. After hypophysin injection kidney purification of sodium, potassium and chloride ions has been noticed and hypophysin effect on tubular absorption processes turned out to be clearly late in relation to its influence on glomerular filtration decrease. After desoxycorticosterone-21-acetate injection, lowering of clearances of both sodium and potassium has been noticed and it may prove that kidney mechanisms responsible for potassium ion regulation show functional immaturity. Hypophysin and desoxycorticosterone-21-acetate in calves at the age 2-5 weeks have not affected kidney processes of calcium, magnesium and inorganic phosphorus excretion in urine.
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PMID:[Effect of hypophysin and desoxycorticosterone-21-acetate on renal function in calves in the neonatal period. II. Urinary excretion of electrolytes]. 248 70

Nippostrongylus brasiliensis infection of the rat resulted, at day 10 of infection, in decreased levels of jejunal enterocyte sodium-potassium-activated adenosine triphosphatase (Na,K-ATPase) and potassium-activated p-nitrophenyl phosphatase (K-pNPPase) activities. Parallel decreases occurred in active sodium efflux from jejunal enterocytes in the presence and absence of actively transported monosaccharides. Ileal enterocyte Na,K-ATPase and K-pNPPase activities were significantly increased, as was active sodium efflux. In contrast to controls, the presence of monosaccharides produced a stimulation of active sodium efflux from ileal enterocytes derived from infected rats. Enzyme and sodium transport changes in the jejunal enterocytes probably reflect cellular immaturity. Functional changes in ileal enterocytes probably represent a compensatory phenomenon.
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PMID:Changes in Na,K-ATPase, sodium ion, and glucose transport in isolated enterocytes in an experimental model of malabsorption. 255 21

1. Red cell pyruvate kinase (EC 2.7.1.40) and hexokinase (EC 2.7.1.1) in high and low potassium (K) dogs were shown to exist as multiple forms which were separable by electrophoresis and ion-exchange chromatography. The R2-type pyruvate kinase, which was determined to be a young type enzyme in canine red cells, was shown to be the predominant form of pyruvate kinase in high K cells. 2. The M2-type pyruvate kinase, a prototype isozyme in erythroid cells, existed in high K dog erythrocytes as well as in high K and low K dog reticulocytes. 3. Isozyme analysis of high K red cell hexokinase also showed a profile similar to that obtained for low K reticulocytes. 4. These results seem to reflect the immaturity of high K erythrocytes, which suggest that an abnormal cell differentiation or maturation may occur at an early stage of erythroid cell proliferation in high K dogs.
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PMID:Inherited persistence of immature type pyruvate kinase and hexokinase isozymes in dog erythrocytes. 270 33

A new model of renal cystic disease was developed in newborn Syrian hamsters by the repeated injection of 9-fluoroprednisolone acetate (9-FPA), a long-acting adrenal corticosteroid. Kidneys harvested from the tenth to the fourteenth day of age showed diffuse cystic dilatation of nearly all cortical convoluted tubules. Microdissection revealed that cystic changes primarily involved proximal convoluted tubules and, to a lesser degree, the distal tubules. Electron microscopy showed immaturity of development and varying degrees of degeneration of the cells of the proximal convoluted tubule. Intraluminal obstruction was not detected and therefore could not account for the cystic changes. Analysis of electrolytes in serum and selected tissues showed a significant reduction in potassium and sodium of serum, and significant depletion of potassium, magnesium and calcium in the skeletal muscle. Thus, there was no direct relationship between an electrolyte deficiency and the cystic changes.
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PMID:Adrenal corticosteroid-induced renal cystic disease in the newborn hamster. 472 95

Iodide-induced hypothyroidism with high TSH and low T4 under long term potassium iodide medication was observed in a toddler suffering from chronic wheezy bronchitis -- in spite of intermittent application. The pathophysiology of iodide-induced hypothyroidism and the apparent immaturity of adaptation to high exogenous iodide in newborn and infants are discussed.
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PMID:[Hypothyroidism following intermittent administration of potassium iodide]. 669 43


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