摘要:

SummaryThis paper describes a study comparing the impedance cardiac output (ICO) with effective pulmonary capillary blood flow (&OV0422;pc eff), measured by rebreathing N2O, in a group of healthy babies during the neonatal period. The calculation of ICO requires a value for the electrical resistivity of blood, p. The resistivity of blood was measured on 40 samples of neonatal blood with hematocrit range of 18–70% and a new relationship was defined between haematocrit and resistivity, wherebyp= 67.919 exp (0.02433 Het) (Fig. 2). A total of 109 simultaneous measurements of &OV0422;pc eff and ICO, made from 32 different babies studied upon 41 occasions, was considered for correlation purposes (Table 2). The different methods are plotted against each other in the graphs (Fig. 3). It is seen that using any one of the available data for human blood resistivity alone, a good correlation between ICO and &OV0422;pc eff is only achieved over a part of the haematocrit range. A hematocrit-related correction factor, S, has been derived to be applied to the stroke volume equation. The corrected ICO compared with &OV0422;pc eff results is shown in Figure 5 and the correlation coefficients and percentage differences between the two methods for the different hematocrit groups are shown in Table 2. The mean ICO is 205 ml kg1min1SEM 3.5 (range 124–289).Impedance cardiography is a safe and easy technique to apply to the newborn human infant but even if accurate values for resistivity are used, a further hematocrit-related factor should be applied for optimal results.SpeculationA technique having been established by which impedance cardiography can be used to make accurate measurements of cardiac output in the healthy newborn infant, it is now possible to use this method to provide noninvasive observations on the normal cardiovascular physiology of the newborn and to assess its potential for making clinically useful measurements on sick infants.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryMilk samples from 100 lactating mothers in the 10 days following delivery have been analyzed for pH, sodium, and potassium. The sodium concentration was high in the first 5 days, mean 21 ± 5 mmol/liter, but fell to a mean 15 mmol/liter by the end of the first week and 12 mmol/liter by the 10th day. A similar downward trend was shown for potassium with an initial mean concentration of 18.5 mmol/liter falling to 15 mmol/liter by the 10th day. The pH fluctuated widely from day to day through a range of 6.75–7.42 with a mean pH 7.09. Considerable variations were shown in individuals from day to day, and from the beginning to the end of feeds (Table 1).The relatively high sodium concentration in the firs> few days may be an important defense mechanism against dehydration and hyponatremia during a period of relative thirst and starvation. The variation in the pH and electrolyte content of human milk may be expected to have some influence on the acid-base and electrolyte status of the infant.SpeculationHyponatremia and acidosis in neonates in the first few weeks may be attributed in part to the inappropriate pH and electrolyte content of artificial milk formulas based on mature human milk. The addition of sodium and base to formulas may be a desirable modification both for premature infants and for term infants in the first few weeks of life.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryThis study was conducted in 41 premature infants during the first 48 hr of life to investigate the effect of a constant calcium infusion on serum calcium, phosphorus, magnesium, immunoreactive parathyroid hormone (iPTH), and immunoreactive calcitonin (iCT) in low birth weight infants (LBW). The infants were divided into two comparable groups. A control group (group I) included 16 infants who received a 10% glucose solution; a calcium group (group II) included 25 infants who received a 10% glucose solution with calcium gluconate, the amount of mineral calcium perfused being 35 mg/kg/day or 1.7 mg/kg/day. No overall adverse effects were observed in the infants receiving the Ca infusion.In the first group, mean serum Ca level decreased rapidly during the first 24 hr of life from 8.9 ± 0.7 mg/100 ml to 6.79 ± 1.07 mg/100 ml at 22–26 hr (P< 0.001) without any further significant change. In the second group, the mean serum Ca level remained stable from 1–3 hr (8.51 ± 0.61 mg/100 ml) to 44–48 hr (8.33 ± 0.94 mg/100 ml). The mean Ca levels were significantly higher ingroup IIat 10–14 hr and 22–26 hr (P< 0.001). There was no significant change in mean serum P levels in both groups. The mean serum Mg levels were significantly higher ingroup IIfrom 22–48 hr. Mean serum iPTH levels increased in both groups from 1–3 hr to 44–48 hr (P< 0.001) without significant difference at any time between the two groups. The mean serum iCT level showed a marked increase from 1–3 hr to 10–14 hr or 22–26 hr in both groups (P< 0.001) without significant difference between the two groups. In both groups of infants a negative correlation was observed between serum iCT and serum Ca levels at 22–26 hr. Ingroup I, mean serum iCT levels decreased during the second day of life, whereas ingroup IIthere was no further significant change in mean serum iCT.These data suggest that the administration of a continuous intravenous perfusion of calcium can prevent early neonatal hypocalcemia in low birth weight infants without depressing the parathyroid activity in the majority of the infants. They also indicate that the hypercalcitoninemia which is observed during the neonatal period is not closely dependent upon the serum Ca level; however, the finding of negative correlations between serum Ca and serum iCT levels suggests that the elevated serum iCT levels have a depressive effect upon serum Ca in low birth weight infants.SpeculationThe use of a prophylactic continuous calcium infusion has been advocated to prevent early neonatal hypocalcemia of low birth weight infants. In the normal adult calcium infusion is known to depress the parathyroid function and may stimulate the secretion of calcitonin. We wished to determine the effects of early continuous calcium infusion on serum parathyroid hormone and calcitonin levels in low birth weight infants.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryTo date, no information is available on whether human growth hormone (hGH) exerts an influence on digestive processes in man. To test this, we studied the composition of the aqueous (micellar) phase during the digestion of two consecutive meals in growth hormone-deficient individuals and in control subjects, before and after replacement therapy with hGH.Before treatment, the average micellar bile acid concentration was 5.0 ± 0.6 mM (normal adults and controls subjects: 6–15 mM) during the first meal, and 3.5 ± 0.9 mM (normal adults and control subjects 5–10 mM) during the second meal. After 1 year of treatment, the mean micellar bile acid concentration increased to 9.7 ± 1.0 mM (P< 0.02) during the First, and to 7.1 ± 0.3 mM (P< 0.01) during the second meal. Concomitantly with an increased micellar bile acid concentration, micellar lipid increased as well (effect of treatment: (1) fatty acid, first meal 6.3 ± 0.6 mM to 13.0 ± 0.7 mM,P< 0.001; second meal 4.5 ± 1.5 mM to 8.5 ± 0.3 mM,P< 0.05; (2) monoglyceride, as percentage of total fatty acids: first meal 25 ± 10 to 53 ± 7,P< 0.02; second meal 31 ± 7 to 62 ± 6,P0.02).Short term treatment (10 days) did not have an effect on the concentration of micellar bile acids and lipids in the control subjects. There was no significant difference in the physical state of bile acids and lipids between patients and control subjects before and after treatment.SpeculationThe digestion of dietary lipid involves a sequence of important steps: after emulsification, lipolysis generates fatty acids and monoglyceride, which require dispersal by bile acids (above their critical micellar concentration) for transport through the aqueous milieu to the membrane of the enterocyte. The “physiologic micellar concentration” of bile acids in the intestine during a meal for the efficient micellar dispersal of lipid is between 3 and 4 mM.The increase of the intestinal micellar bile acid concentration from borderline to normal adult levels after replacement therapy with growth hormone could be explained as follows. The increased concentrations of bile acids in the intestine after treatment was the result of an increased hepatobiliary secretion of bile acids. This could have been effected by a growth hormone-mediated increase of hepatic bile acid synthesis, or through increased storage capacity of the gallbladder. The latter is probably best explained by a growth hormone-stimulated secretin effect, rather than an effect of gallbladder emptying. Further, increased availability of bile acids for lipid digestion could also result from their improved intestinal conservation (absorption).The clinical implications of the results reported in this study are indirect, but may point towards an interrelationship between hormonal stimulation and certain aspects of hepatobiliary function, which influence digestive processes.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryGlycine content and enzyme activity of the glycine cleavage system were compared in autopsied brain from five infants dying with glycine encephalopathy and four control infants, including two with other types of hyperglyeinemia. Glycine content was elevated 2− to 8-fold and glycine cleavage enzyme activity was undetectable in the brains of the glycine encephalopathy patients. Glycine content and enzyme activity were normal in the brains of the control patients, including one with ketotic hyperglyeinemia secondary to methylmalonic acidemia. Prolonged dialysis failed to restore glycine cleavage enzyme activity in brain homogenates of glycine encephalopathy patients, and these homogenates failed to inhibit enzyme activity when added to homogenates of control brain. Radioactive bicarbonate was converted to radioactive glycine by control brain, but not by glycine encephalopathy brain. This Finding, together with the results of recombination experiments between solubilized human brain enzymes and purified protein components of the bacterial glycine cleavage system ofArthrobacter globiformis, indicates that the enzyme defect in glycine encephalopathy involves at least the second or H protein of the 4-protein glycine cleavage enzyme system.SpeculationThe severe neurologic syndrome that characterizes glycine encephalopathy, in contrast to some other forms of hyperglycinemia, is probably caused by absence of glycine cleavage enzyme activity and marked elevation of glycine content in infantile brain. Since symptoms of this inherited disorder only appear shortly after birth, a firmly bound endogenous inhibitor of the glycine cleavage enzyme may accumulate in brain of affected infants, who have been protected during fetal life by clearance of the putative inhibitor across the placenta.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryA male child died at 7 months of age with progressive neurologic deterioration and persistent metabolic acidosis. Investigations during life showed this child to have elevated blood pyruvate, lactate, and α-ketoglutarate as well as elevation of branched chain amino acids and occasional hypoglycemia. Co-factor therapy using either thiamine-HCI (2 g/kg/24 hr) or thiamine tetrahydrofurfuryl disulfide had no measurable effect on the clinical or biochemical status of the patient. Tissue taken postmortem showed normal levels of key gluconeogenic enzymes but a deficiency in the activity of pyruvate dehydrogenase in all tissues tested (liver, brain, kidney, skeletal muscle, and heart). Examination of the individual activities of the pyruvate dehydrogenase complex showed pyruvate decarboxylase (E1) to be normal in liver and other tissues. Dihydrolipoyl dehydrogenase (E3), on the other hand, was deficient in all tissues tested. α-Ketoglutarate dehydrogenase complex, which depends on E3for its total activity, was also deficient in all tissues tested. The absence of this enzyme is discussed in relation to the clinical and biochemical status of the patient.SpeculationCongenital lactic acidosis due to a severe defect in the pyruvate dehydrogenase complex for the first time has been shown to be due to the absence of the E3enzyme of the pyruvate dehydrogenase complex, dihydrolipoyl dehydrogenase. The survival of this infant for 6 weeks of life without hospitalization is suggestive of a reliance on glycolytic rather than oxidative metabolism in the early neonatal period.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryAlveolar macrophages (AMs) obtained from 1-day-old rabbits showed high levels of phospholipid, protein, UNA, and RNA compared to those obtained from 7-day-old, 28-day-old, or adult rabbits. The surfactant material released in alveoli during the perinatal period is extensively phagocytosed by AMs, and appears to be primarily responsible for high phospholipid content of these cells. The high protein, UNA, and KNA levels of AMs may result from phagocytosis of cellular debris.Of the six lysosomal enzymes of AMs studied, acid phosphatase (AP) and lysozyme activities showed a decline in the first postnatal week. In AP this was followed by no significant change. A steady rise in lysozyme activity after the seventh postnatal day was observed. The activities of cathepsin D and DNase did not show significant changes, whereas β-glucuron-idase and RNase activities of AMs increased significantly within the first postnatal week.The activities of glucose-6-phosphate dehydrogenase (G-6-PU), 6-phosphogluconate dehydrogenase (6-PGU), lactate de

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryPhagocytic and bactericidal function of rabbit alveolar macrophages (AMs) lavaged from animals during the course of postnatal maturation was studied.Staphylococcus aureusand a temperature-sensitive mutant ofEscherichia coli, which could not replicate at 37° during the functional assays, were employed as test bacteria. Assays of the phagocytic capacity of AMs from rabbits of various age groups revealed no significant differences either in the percentage of AMs which took up bacteria (79–90%) or in the number of bacteria taken up per AM (Table 1). In contrast, bactericidal activity of AMs was found to increase with increasing animal age. No bactericidal activity was detected in AMs from newborn animals (Figs. 1 and 2), whereas AMs from 7-day-old animals exhibited at least a bacteristatic activity againstS. aureus(Fig. 1) and AMs from 28-day-old rabbits snowed marked bactericidal activity, essentially the same as that of AMs from adult rabbits. Adult AMs killed 75% of theS. aureusand 60% of theE. coliwithin 120 min (Figs. 1 and 2).SpeculationThe development of bactericidal activity in AMs during the postnatal period correlates with their previously reported morphologic and biochemical maturation. This developmental pattern of bactericidal activity may indicate that the mechanisms responsible for bacterial killing may not be fully developed at birth but develop during extrauterine life. Alternatively, the large quantities of phagocytized surfactant-like material known to be present in the AMs in the early postnatal period may inhibit their bactericidal activity.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

SummaryAntibodies of restricted specificity have been identified in the human in response to certain antigens. The present study analyzed tetanus and diphtheria antitoxins isolated from selected human sera and suggested a restricted response in antibody production to each of these antigens. Purified antibodies from eight serum specimens with elevated hemagglutination titers to tetanus and four to diphtheria yielded only IgG proteins in concentrations of 160–500 μg/ml. Although some of the tetanus specimens were derived from cord sera and tetanus immunoglobulin, none of the total group had antibodies of the IgA and IgM classes. Utilizing immunoelectrophoresis against heavy chain subclasses, genetic markers, and κ and λ quantitations, a predeliction for the κ IgG1subclass was established for both tetanus and diphtheria antibodies. The λ light chains were present in diminished quantities, IgG2heavy chains were absent, and the IgG3and IgG4chains were variably identified.SpeculationThe elucidation of those antigens which result in restricted antibody formation has apparent clinical significance, in view of the fact that some individuals possess selective defects in the production of certain IgG subclasses.

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1977

数据来源: OVID