摘要:

SummaryPlasma parathormone (PTH) and calcium concentrations were measured in 309 specimens collected from 190 newborns during the first 7 days of life. The patient material consisted of 51 preterm, 130 term, and 9 postterm infants, including 22 infants of diabetic mothers (IDM), 38 infants with hypocalcemia, and 25 asphyxiated infants. PTH was detectable, although in low concentrations, in cord blood samples despite the presence of elevated calcium concentrations. Postpartum, PTH concentrations in term, appropriate for gestational age (AGA) infants remained low during the first 2 days of life; a significant (P< 0.05) and sustained increase in plasma hormone levels was noted starting on day 3. PTH concentrations in IDM and preterm infants remained low for 3 days and a significant hormone increase did not occur until day 4.Hypocalcemia was common in IDM and asphyxiated infants; these infants accounted for two-thirds of all hypocalcemic infants. The profile of plasma calcium in IDM during the first week of life was different than that of any other group of infants. Plasma calcium concentrations remained depressed over this period of time and exhibited a temporary drop on day 4 accompanied by an increase in plasma PTH levels. Asphyxiated infants exhibited low plasma calcium concentrations, despite PTH levels that were significantly (P< 0.007) higher than those of age-matched term AGA newborns.SpeculationBasal PTH secretion is present at birth, several days before the parathyroid glands appear to become responsive to hypocalcemia. Furthermore, in cord blood PTH is detectable in spite of elevated calcium concentrations. The present observations suggest that nonsuppressible PTH secretion, previously described in short-term animal experiments, also occurs in the human fetus exposed to long-standing intrauterine hypercalcemia, with the implication that PTH secretion in man may be regulated by control mechanisms in addition to calcium feedback. There is anatomical and pharmacologic evidence to implicate the autonomic nervous system in this control.

ISSN:0031-3998    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SummaryThe body composition (percent body fat) at vaginal opening of groups of rats fed different diets was determined. Serial changes in body composition prior to vaginal opening were also measured to assess the temporal relationship between first achievement of the body composition subsequently found at puberty and the actual onset of puberty (vaginal opening). The body weight at vaginal opening and the total carcass fat at vaginal opening were significantly different among the three dietary groups (F = 43.06 and 44.60, respectively;P< 0.001). In addition, the percent body fat at vaginal opening was also significantly different among the three dietary groups (F = 30.30;P< 0.001). In one group, the percent body fat was the same at the age of 31 days as it was at vaginal opening (mean age 41 days). In a group where food intake was restricted, the percent body fat prior to and at vaginal opening remained lower than that seen at vaginal opening in a group fed the same diet ad libitum. Thus, attainment of a critical level of body weight, total body fat stores, or percent body fat does not trigger puberty in rats.SpeculationSexual maturation and body fat accumulation may be parallel but asynchronous processes which reflect completion of an animal's early period of rapid growth.

ISSN:0031-3998    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SummaryThe acetylcarnitine concentration in amniotic fluid fell significantly between 33 and 37 and 40 weeks of gestation. It was significantly higher in samples that had a low lecithin to sphingomyelin ratio. The acetylcarnitine content of tracheal fluid was higher in samples obtained from premature newborns. The major excretory form of carnitine is the acetate ester and only in adults does the urine contain significant amounts of free carnitine. The level of acetylcarnitine in plasma significantly increases after the first day of life; there was no difference in the plasma levels of carnitine between full-term and premature newborns. Plasma-free carnitine and acetylcarnitine levels were significantly lower in infants who were receiving a soybean-based formula. A positive correlation was found between the plasma level of ketone bodies and that of acetylcarnitine.SpeculationA characteristic of early postnatal adaptation in human newborns is a high dependence on the utilization of fatty acids derived from endogenous sources and increasingly from digested milk triglycerides. This essential energy-producing mechanism seems to be facilitated by carnitine, of which a considerable amount is derived from milk.

ISSN:0031-3998    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SummaryCell-mediated immunity (CMI) was examined in 74 children with acute rheumatic fever (ARF) grouped as with or without carditis and inactive disease with valvular lesions and 26 healthy controls of the same age.Absolute lymphocyte count, skin tests with PPD, Candida, and streptokinase streptodornase (SK-SD) antigens were employed. The lymphocyte transformation test was performed by using phytohemagglutinin (PHA), SK-SD, Candida, and cardiac antigens, and incorporation of tritiated thymidine into DNA was measured.Absolute lymphocyte counts in all groups were not significantly different than those of controls. Skin test responses to PPD, Candida, and SK-SD antigens were significantly decreased in patients with rheumatic activity. In contrast, inactive rheumatic patients with valvular lesions showed higher percentages of positive reactions which were not significantly different than those of the healthy controls. Thein vitroresponse to PHA was decreased in active rheumatic fever (RF) patients, whereas patients with inactive RF with valvular lesions showed a hyperactivity to this mitogen. Patients with inactive RF with valvular lesions also exhibited an exaggerated cellular reactivity to SK-SD antigen, but the patients in active groups showed more of a decreased reactivity than did the controls. Patients with evidence of rheumatic carditis exhibited the same degree of cellular reactivity to these antigens and mitogen as did patients without clinical evidence of rheumatic heart disease. Candida did not cause significant stimulation of blastic transformation in any of the study groups. The blastic transformation response to heart homogenates was present in 25% of the cases with active rheumatic carditis, in 15% without carditis, and in 46% of the patients with inactive valvular lesions.Plasma from the patients with active RF caused inhibition of thein vitroresponse of the normal lymphocytes to PHA.In the last few years, it has become increasingly apparent that, in addition to the well documented alterations in humoral immunity, ARF is also accompanied by abnormalities in cell-mediated immunity (CMI) where the precise significance in pathogenesis of rheumatic carditis remains controversial.SpeculationPatients with active rheumatic fever may have depressed cellular immune responses bothin vivoandin vitroto PHA and specific antigens. Observations on the responses to SK-SD and heart homogenate in inactive rheumatic fever patients suggest that patients with rheumatic carditis build up a cellular immune response to the heart.Our findings also suggest that the possibility of lymphocyte sensitization by heart tissue antigens might play a part in the pathogenesis of rheumatic carditis. But the reason for hyporeactivity and the exact link if any between lymphocyte abnormalities and tissue lesions of rheumatic carditis remain to be elucidated.

ISSN:0031-3998    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SummaryIntravenous phenylalanine loading tests were performed in 22 children affected by different types of hyperphenylalaninemia: six cases of classical phenylketonuria (PKU), six cases of atypical PKU, five cases of mild permanent hyperphenylalaninemia, three cases of “transient” PKU, and two cases of the “new variant with progressive neurological illness resistant to dietary treatment,” one of them suffering from DHP reductase deficiency and the other being affected by a defect in biopterin synthesis. A 0.06 M L-phenylalanine (500 ml/m2) solution in NaCl was perfused during 3 hr so that a plasma level of about 2-3 µmol·ml-1was obtained. Results were compared to those obtained in five controls.In classical, atypical, and mild types, a first order kinetics was observed; the constant of the disappearance rate (k) was, respectively, 2.5, 4.6, and 8.5 X 10-4·min-1, the differences being highly significant (P< 0.001). Expressed as a function of the value of k found in controls (1.37 X 10-2·min-1), these figures represent, respectively, 1.8,2.4, and 6.2% of the normal. A first order kinetics was observed also in the new variant, the values of k (3.5 and 4.4 x 10-4·min-1) being similar to those found in atypical PKU. On the other hand, in the so-called transient PKU, the kinetics of disappearance is a zero-order one. Moreover, the tune course of fall is, on an average, 48 hr, thus demonstrating the persistance of a metabolic disorder in spite of the subnormal plasma levels (0.2–0.3 µmol·ml-1) on a regular diet.The results demonstrate that in the common variants (classical PKU, atypical PKU, and mild forms) the disappearance rate constant of phenylalanine after an intravenous perfusion is proportional to the residual hydroxylase activity as assayed in liver biopsies. They suggest that transient PKU, which is, in fact, a permanent condition, might result from the accumulation of an intermediate, the concentration of which remains constant during the hydroxylation process. Finally, in spite of a normal hydroxylase activity in thein vitrosystem, anin vivohydroxylation rate of 3 and 4% of the normal was found in the two children affected by the new variant, which is in good agreement with their daily tolerance and their fasting phenylalanine plasma level on a regular diet.SpeculationThe demonstration of a zero-order kinetics of phenylalanine disappearance in transient PKU suggests the accumulation of an intermediate released during the hydroxylation process, which might occur from a phenylalanine hydroxylase-stimulating protein defect.

ISSN:0031-3998    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SummaryThree human infants with hypertensive obstructive hydrocephalus were treated with oral doses of digoxin beginning on the 2nd, 7th, and 13th week of postnatal life, respectively. One infant received 0.015 mg/kg/day and two infants were given 0.010 mg/kg/day of digoxin. The drug failed to alleviate any clinical signs of elevated intracranial pressure. Groups of 10-day-old infant rats were acutely digitalized by sc administration of three successive doses of digoxin (3 mg/kg body wt) at 20-min intervals. In the first group electrocardiograms and electroencephalograms were monitored. Additionally, arterial blood pressure was monitored by means of an aortic catheter. The electroencephalographic and cardiovascular response differed from controls only by minor changes in the ECG wave-form (increased amplitude of the QRS and T-waves). In the second group the rate of bulk flow [or cerebrospinal fluid (CSF) formation] was assessed by 5-min intrathecal infusion of14C-inulin, performed 20 min after the last injection of digoxin.Comparative values for inulin clearance from the CSF system (µl/min) of experimental and control animals were calculated from inulin concentrations in CSF at stated intervals of 15-22, 22-30, 30-45, and 45-60 min after the last dose of digoxin. Rates of CSF formation were depressed to about 50% of control levels at 15 min, reaching a state of complete arrest between 22 and 45 min, and followed by rapid recovery to resting levels at 60 min. In the third experimental group of digitalized infant rats, concentrations of 5-hydroxyindoleacetic acid (5-HIAA) in CSF and brain were assessed 80 min after the last injection of digoxin. Although no significant change in the amounts of 5-HIAA was found in brain tissue, the 5-HIAA concentrations in the CSF of digoxin-treated rats rose to values that were 140% greater than found in controls.An additional group of 10-day-old rats was killed 60 min after se injection of probenecid, 250 mg/kg body wt. Probenecid, a drug which competitively inhibits carrier-mediated transport of 5-HIAA from both the brain and CSF system, increased both brain and CSF concentrations of 5-HIAA by 55 and 432%, respectively.SpeculationWe speculate that, although digoxin, in doses not toxic to the cardiovascular system, can completely arrest fluid secretion by the choroid plexus of the rat, its duration of action is too brief, rendering it useless for the treatment of chronic hydrocephalus in man.We also speculate that, despite the presence of efficient transport mechanisms localized to the brain parenchyma as well as the choroid plexus, the circulation of CSF is necessary for efficient elimination of acid metabolites from the central nervous system.

ISSN:0031-3998    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SummaryA tracheal ring explant system, when used with 25% cystic fibrosis (CF) serum, displayed obvious ciliostasis. Hamster, rabbit, and guinea pig explants all had measurable decreases in ciliary activity after 24 hr of incubation in the serum. The differential response to CF serum (relative to normal serum) was greatly increased by using explants which were maintained 24–72 hr in minimal essential medium (MEM) with 10% horse serum and which were selected on the basis of optimal ciliary activity and vigor. With such a bioassay system of guinea pig tracheal explants, incubation with 25% normal serum would produce essentially no change in relative ciliary activity (score of 242 of a possible 300), whereas CF serum resulted in an 86% decrease (score of 33). Scanning electron microscopic observation indicated that the explants displaying the CF-ciliostatic effect had significant accumulations of mucous over the ciliated epithelial surface. A biochemical viability assay (dehydrogenase activity) showed no cytonecrosis when CF serum-treated tissues were compared to standard explants (10% horse serum in MEM) or control explants (25% normal human serum).SpeculationCystic fibrosis serum, when tested at 25% concentrations on preselected guinea pig tracheal ring cultures, showed an obvious and easily measurable ciliostatic response. This new bioassay may serve as an improved model to detect and analyze the CF dyskinesia factor.

ISSN:0031-3998    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SummaryBasal and pentagastrin-stimulated gastric acid secretion was measured in 26 healthy newborn infants on the 1st and 2nd days of life. Basal acid outputs (BAO) on day 1 (0.378 mEq/hr) and day 2 (0.388 mEq/hr) were similar and not significantly different from the maximal acid outputs (MAO) on day 1 (0.413 mEq/hr) and day 2 (0.452 mEq/hr). When calculated on a mEq/kg/hr basis, BAO on day 1 was 0.110 with an MAO of 0.122. The BAO on day 2 was 0.114 with an MAO of 0.133. Fasting serum gastrin levels obtained before the acid studies on each day were elevated (mean, day 1 = 100 pg/ml; mean, day 2 = 108 pg/ml). These findings suggest that either gastric acid secretion in the newborn is maximal under basal condition or that newborn parietal cells are unresponsive to pentagastrin on day 1 and 2 of life.

ISSN:0031-3998    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SummaryNormal values are given for the activities of pyruvate carboxylase (E.C. 6.4.1.1), mitochondrial phosphoenolpyruvate carboxykinase (E.C. 4.1.1.32, PEPCK), and citrate synthase (E.C. 4.1.3.7) in fibroblasts, lymphocytes, and leukocytes. Also given are values for these enzymes in the leukocytes and fibroblasts from a severely mentally and developmentally retarded patient with proximal renal tubular acidosis and hepatic, cerebral, and renal cortical pyruvate carboxylase deficiency. In normals, virtually all of the mitochondrial PEPCK and pyruvate carboxylase activity was present in the mononuclear leukocyte fraction of whole venous blood. Cellular fractionation studies with human lymphocytes and fibroblasts demonstrated that all of the PEPCK activity in these cells is mitochondrial. Normal values for pyruvate carboxylase in leukocytes were 0.092 (0.070–0.208) mU/mg protein (n = 5), in lymphocytes 0.154 (0.092–0.262) raU/mg protein (n = 5), and in fibroblasts 136 (0.778–2.19) mU/mg protein (n = 5). The patient with hepatic, renal, and cerebral pyruvate carboxylase deficiency had no detectable activity (<0.009 mU/mg protein) in his leukocytes and 0.018 mU/mg protein in his fibroblasts. Data from an assay for pyruvate carboxylase activity in the patient's fibroblasts show that the activity observed is significant but very close to the lower limits of the assay. Values for PEPCK in normal lymphocytes were 1.42 (0.824–1.88) mU/mg protein (n = 5), in leukocytes 1.68 (1.64–1.72) mU/mg protein (n = 2), and in fibroblasts 5.49 (3.94–6.33) mU/mg protein (n = 6).SpeculationThe absence of pyruvate carboxylase in the lymphocytes and fibroblasts of a patient with hepatic, renal, and cerebral pyruvate carboxylase deficiency supports the hypothesis that only one form of pyruvate carboxylase exists in the human and suggests that the examination of lymphocytes or fibroblasts for pyruvate carboxylase activity may be a valid method for diagnosing this disease. Furthermore, our results suggest that family studies and prenatal diagnosis may be possible for pyruvate carboxylase deficiency.

ISSN:0031-3998    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SummaryA model of salicylate intoxication was developed in ferrets to permit the evaluation of the interaction with viruses isolated from patients with Reye's syndrome. Salicylate intoxication produced mild elevation of the serum glutamic oxaloacetic transaminase and fatty changes in the liver, but these changes differed from those seen in Reye's syndrome on light and electron microscopy. Salicylates were associated with decreased activity of hepatic phosphorylase and a slight depression of activity of ornithine transcarbamylase, a mitochondrial urea cycle enzyme. Infection with influenza viruses produced mild fatty changes in the liver, but did not significantly potentiate the effects of salicylate intoxication on the over-all mortality, the degree of fatty changes, or the hepatic enzymes. Influenza infection alone was not associated with decreased hepatic phosphorylase activity, but was associated with decreased activity of ornithine transcarbamylase. Influenza A was isolated from the livers of two of four animals cultured in embryonated eggs.SpeculationBecause of its susceptibility to human influenza viruses, the ferret provides an animal model to evaluate potential toxic cofactors in the production of Reye's syndrome.

ISSN:0031-3998    

出版商:OVID    

年代:1979

数据来源: OVID