摘要:

SummaryStudies were performed to determine the effects of iron deficiency on brain metabolism in rats. Concentrations of cytochrome pigments, oxidative phosphorylation, and catalase and monoamine oxidase activities in brain tissue were unaffected by iron deficiency. However, activities of aldehyde oxidase, a key enzyme in the pathway of serotonin degradation, were significantly reduced, and concentrations of serotonin and total 5-hydroxyindole compounds were elevated in brain tissue of iron-deficient animals. Aldehyde oxidase activities and concentrations of 5-hydroxyindole compounds in brain tissues returned to approximately normal values one week after treatment of iron deficient animals with iron dextran.SpeculationStates of iron deficiency may result in reduction of important iron containing enzymes in brain tissue and altered brain metabolism.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SummaryAt 0–3 days of age the plasma ammonium concentration in full term appropriate for gestational age (AGA) infants was (mean ± SEM) 27.5 ± 0.5 μM; a value similar to that reported in adults. Ammonium levels in low birthweight AGA and SGA groups were 47.0 ± 2.0 μM and 45.1 ± 3.3 μM respectively; significantly elevated (P< 0.001) as compared to the full term group. These increased ammonium levels persisted at 3–5 weeks of age. Associated with the hyperammonemia was a significant (P< 0.01) decrease in plasma α-ketoglutarate concentration: 11.8 ± 1.0 μM, in the low birthweight AGA as compared to 20.7 ± 0.6 μM in the full term AGA infants. There was an inverse linear correlation between plasma concentrations of ammonium and α-ketoglutarater= −0.86,P< 0.001. Urinary orotate excretion was significantly elevated (P< 0.05) in low birthweight AGA infants. There was no difference in the plasma concentrations of glutamine, glutamate, or alanine among the various groups. Hyperammonemia was not associated with neurologic dysfunction.SpeculationThere is a greater accumulation of ammonium in low birthweight as compared to full term infants. This may be a consequence of a developmental delay of one or more of the enzymes required for urea synthesis. Alternatively, the hyperammonemia may be related to arginine and/or ornithine diversion out of the cycle and incomplete repletion of ornithine from glutamate via the Δ′-pyrroline-5-carboxylate pathway.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SummaryThis investigation was undertaken to determine the nature of acute alterations in renal function following the production of hypoxemia, hypercarbia, and acidosis in newborn piglets 6–96 hr of age. After completion of the surgical procedure piglets were allowed to recover from the effects of anesthesia. When respiratory dead space was increased arterial oxygen tension decreased whereas arterial carbon dioxide tension and hydrogen ion concentration increased. There was little change in glomerular filtration rate. Total renal blood flow decreased and renal vascular resistance increased significantly (504 ± 78 mm Hg/liter/mm/m2to 1422 ± 504). There was no change in distribution of intrarenal blood flow. Sodium excretion and urinary flow rate demonstrated significant parallel increases following the increase in dead space. Plasma renin concentration increased from 67 to 110 ng/ml.SpeculationHypoxia, hypercarbia, and acidosis produced changes in renal function in newborn piglets. Therapeutic approaches to the newborn human with respiratory distress must consider the potential for modifications of renal function which may be detrimental to the infant.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SummaryIn a homozygous affected patient with maple syrup urine disease, pharmacologic doses of thiamine lowered urinary excretion of branched chain α-ketoacids and stimulated branched chain α-ketoacid dehydrogenase (BCKAD) in his peripheral blood leukocytes. Supplementation of his branched chain aminoacid restricted diet with 100 mg/day of thiamine eliminated recurrent episodes of ketoacidosis. These clinical responses were studiedin vitrousing mitochondrial inner membranes prepared from his cultured skin fibroblasts and those from another thiamine-responsive patient from Canada. BCKAD in both mutant cell lines had similarities to normal enzyme including: identical apparent Kmvalue for thiamine pyrophosphate; similar heat inactivation profiles which were slowed by the presence of thiamine pyrophosphate; and stimulation above basal activity by thiamine pyrophosphate. Differences in the enzymes included: decreased apparent Vmaxfor thiamine pyrophosphate; increased lability at 37°; and failure to respond to added NAD+CoASH, and Mg2+.We propose that “excess” thiamine led to increased available thiamine pyrophosphate which stabilized the branched chain α-ketoacid dehydrogenase, decreased biologic turnover, increased enzyme specific activity and producedin vivotolerance to branched chain aminoacids in these patients with maple syrup urine disease.SpeculationBy studying the partially purified normal and mutant branched chain α-ketoacid dehydrogenases from cultured human fibroblasts, directin vitroeffects of thiamine pyrophosphate can be measured and related toin vivoclinical responses. This should improve and extend the treatment and management of patients with maple syrup urine disease and provide a method for study of other mutant human enzymes located in the mitochondrial membrane.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SummaryWe have examined the effect on lung liquid secretion of catecholamines infused in chronically catheterized fetal lambsin utero.Isoproterenol and epinephrine inhibited secretion, an effect which increased with gestation and, in fetuses near delivery, caused absorption of lung liquid. In 7 out of 8 experiments nor-epinephrine had no effect on secretion. This pattern of response and the fact that the inhibitory effect could be blocked by propranolol indicate a mode of action involving β-adrenergic receptors.SpeculationThe observed effects on lung liquid secretion were achieved with infusion rates of epinephrine which are well within the range for endogenous production by the adrenals in response to splanchnic nerve stimulation or asphyxia. Thus the marked increase in the secretion of epinephrine which occurs during parturition may be an important factor in initiating lung liquid absorption. Permanent inhibition of lung liquid secretion postnatally may be due to greater sensitivity of the pulmonary epithelium to β-adrenergic stimulation and to the higher “resting” output of epinephrine from the adrenals of neonates compared with fetuses.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

SummaryTo establish normal parameters, we have measured 14 proteins in 120 amniotic fluid samples from normal second trimester pregnancies. Pregnancy-associated macroglobulin (PAM), identified in 15 samples, has served to indicate contamination with maternal blood; this represents the first time that PAM has been used for this purpose. Albumin, transferrin, α-1-antitrypsin, orosomucoid, IgG, and C3 show great variability in individual concentrations but are generally in proportion to each other, particularly transferrin/albumin, α-1-antitrypsin/albumin, and IgG/albumin. The first two ratios are similar to proportions in adult serum, supporting the concept that most amniotic fluid protein is maternal in origin and moves directly across the amnionic membrane. Levels of low density lipoproteine, C4, IgA, IgM, α-2-macroglobulin, and haptoglobin, all low in amniotic fluid, vary independently both of albumin and of each other. α-1-Fetoprotein levels are normal in all samples, suggesting freedom from gross fetal blood contamination. In the presence of maternal blood contamination, 10 of the 15 samples show clear elevation of at least one protein level; C3, IgA, and α-2-macroglobulin are most frequently abnormal.Similar-protein analyses have also been carried out on 11 samples from pregnancies with anencephaly, 5 with spina bifida, and 3 with fetal demise. Results have been compared with normal and blood-contaminated samples. Most protein concentrations are either high normal or abnormally elevated with anencephaly and fetal demise but not with spina bifida. Of all proteins studied, low density lipoprotein is most reliably elevated with neural tube defects and demise and is least affected by blood contamination. IgM and α-2-macroglobulin are also elevated in a significant percentage of uncontaminated samples. Increased IgA and haptoglobin levels correlate with blood contamination but not with neural tube defects. Low density lipoprotein, IgM, and α-2-macroglobulin may be useful adjuncts in the second trimester prenatal diagnosis of neural tube defects.SpeculationWell defined normal ranges for second trimester amniotic fluid proteins are a prerequisite for applying such measurements to diagnosing fetal dysfunction and understanding transamniotic interactions between mother and fetus. In defining such parameters, the present study first re-enforces the necessity to identify blood contamination and then establishes low density lipoprotein, IgM, and α-2-macroglobulin measurements as potentially useful ancillary studies for the prenatal diagnosis of neural tube defects. Similar testing on samples associated with omphalocele, congenital nephrosis, esophageal atresia, and other major fetal malformations must be carried out to determine whether these measurements may be of further help in second trimester differential diagnosis.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID