ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractThe hypoxanthine concentration in plasma was found to be a sensitive parameter of hypoxia of the fetus and the newborn infant. The plasma level of hypoxanthine in the umbilical cord in 29 newborn infants with normal delivery varied between 0 and 11.0 μmol/liter with a mean of 5.8 μmol/liter, SD 3.0 μmol/liter.Compared with this reference group the hypoxanthine concentration in plasma of the umbilical cord in 10 newborn infants with clinical signs of intrauterine hypoxia during labor was found to be significantly higher, with a range of 11.0—61.5 μnmol/liter, with a mean of 25.0 mu;umol/liter, SD 18.0 μmol/liter.The plasma level of hypoxanthine in two premature babies developing an idiopatic respiratory distress syndrome was monitored. The metabolite was found to be considerably increased, in one of them more than 24 hr after a period of hypoxia necessitating artificial ventilation. The hypoxanthine level in plasma of umbilical arterial blood was followed about 2 hr postpartum in three newborn infants with clinical signs of intrauterine hypoxia. The decrease of the plasma concentration of the metabolite seemed to be with a constant velocity, as it was about 10 μmol/liter/hr in these cases. A new method was used for the determination of hypoxanthine in plasma, based on the principle that PO2decreased when hypoxanthine is oxidized to uric acid.SpeculationThese preliminary results indicate that the hypoxanthine concentration in plasma is a sensitive parameter of hypoxia. It is expected that this metabolite will express the degree of hypoxia quantitatively and regardless of the etiology of the hypoxia. The excretion of hypoxanthine and other purine metabolites in urine might also have diagnostic value.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractHemorrhagic atelectasis was successfully produced in newborn rabbits by pharmacologically narrowing airways leading to alveoli ventilated with oxygen-enriched gas. Between 48% and 62% of alveoli filled with blood cells. Areas of lung with a tendency to collapse were measured by pressure volume studies. Animals given supplemental oxygen retained 56% of total lung volume compared with 79% in the pilocarpine group, which suggested increased effectiveness of antiatelectasis factors in the latter. Less total lung gas was present in the pilocarpine group (4.0 ± 0.4 cc/g) compared with oxygen controls (5.1 ± 0.81 cc/g), which indicated more noninflatable lung. Neither surfactant deficiency nor heart failure needed to be present for pulmonary hemorrhage to occur.SpeculationNeonates are at increased risk of pulmonary hemorrhagic atelectasis because of their incomplete pulmonary anatomic development, if their airways become obstructed while breathing high concentrations of oxygen.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractThere is scant information regarding the contribution made by circulating precursors to pulmonary phosphatidylcholine synthesis in the developing mammalian lung.In situpulmonary artery perfusions were performed in term New Zealand newborn rabbits with physiologic buffer containing either 3.6 mM or 10.8 mM glycerol. There was a twofold increase in nanomoles of glycerol-phosphatidylcholine synthesized at 30 min when the higher concentration of glycerol was used. Continuing with the higher concentration, a near three-fold increase was observed between the 30-min and 60-min perfusions. This data indicates that thede novosynthesis of pulmonary phosphatidylcholine is influenced by the concentration of glycerol in the perfusate as well as the duration of perfusion.SpeculationThe observation that the concentration of circulating glycerol can influence thede novosynthesis of pulmonary phosphatidylcholine suggests that glycerol may also play a role in providing precursor for pulmonary surfactant synthesis. The biochemical similarity of lipid metabolism at birth between human newborn infants and the newborn rabbit encourages extrapolation of this data to humans. The question is raised as to the influence that intravenous glycerol at physiologic concentration would have on pulmonary phosphatidylcholine synthesis in the infant with hyaline membrane disease.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractHuman adult and umbilical cord-derived leukocytes were shown to be capable of generating tissue factor activity on exposure to endotoxin and to reduced pH. Blood for leukocyte separation was collected from normal adults and from newly delivered sections of umbilical cord and mixed leukocyte preparations were obtained by separation over methyl cellulose Hypaque. The coagulant activity of the cell suspension was assayed using a one-stage or two-stage method. Cord-derived leukocytes were shown to develop greater coagulant activity than adult-derived leukocytes when stimulated by endotoxinin vitroat 2,000 cells/mm3. This response to endotoxin was partially inhibited by prior exposure of the cells to prostaglandin (PG) E1and to L-epinephrine. Acetylcholine stimulated the production of coagulant activity in the absence of endotoxin. Both cord and adult-derived leukocytes (20,000/mm3developed coagulant activity when exposed to pH reduction by lactic or hydrochloric acids and this activity was shown to be tissue factor.SpeculationTF production by leukocytes (monocytes) after endotoxin stimulation may explain the frequently encountered association of disseminated intravascular coagulation (DIC) with gram-negative septicemia in the newborn infant. The effect of pH reduction in association with hypoxia in the perinatal period, by causing tissue factor (TF) activity to become available, may be the trigger mechanism for the coagulation changes of varying degrees of DIC seen in these situations. Necrotizing enterocolitis could be the result of endotoxin penetration of the bowel mucosa which induces monocyte chemotaxis and local TF production by these cells; this would cause local intravascular coagulation with platelet consumption and necrotic sequelae. It remains to be established whether inhibition of in vivo endotoxin-induced monocyte TF production can be achieved with PGE1, and whether such therapy might improve the outcome in gram-negative septicemia.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractThe recently developed technique of gas chromatography-mass spectrometry supported by computer has considerably improved the analysis of physiologic fluids. This study attempted to demonstrate the value of this system in the investigation of metabolite patterns in urine in two metabolic problems of prematurity, transient tyrosinemia and late metabolic acidosis. Serial 24-hr urine specimens were analyzed in 9 infants. Transient tyrosinemia, characterized by 5–10-fold increases over basal excretion of tyrosine, p-hydroxyphenyllactate, and p-hydroxyphenylpyruvate in urine, was noted in five of the infants. Several infants had fluctuating levels of tyrosine metabolites in urine although dietary protein intake remained constant at 3–4 g/kg/24 hr and ascorbic acid at 50 mg/24 hr. Late metabolic acidosis was seen in four infants, but bore no relation to transient tyrosinemia. The ratio of net acid to urea excretion in urine increased with increasing base deficit, implying a nonprotein origin of the metabolic acid. No unique metabolic patterns were characteristic of late metabolic acidosis.SpeculationAdvances in gas chromatography-mass spectrometry-computer technology (GC-MS-computer) allow for the screening of body fluids for a wide variety of compounds of biologic importance. One application of this technique is for the investigation of the nutritional adequacy of diets for premature infants. Clinical use of these tools may help establish parameters for assessment of nutrition and allow for a rationalization of diet.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractThe sex-differential early neonatal mortality experienced by a population of 27,243 neonates has been analyzed in relation to sex-related reproductive antecedents of their mothers. An association between the risk of dying of a neonate and the sex of previous pregnancies of its mother has been found: the risk decreases with a previous pregnancy of the same sex as the neonate, and increases with one of the opposite sex. Repeated pregnancies of same sex increase the phenomenon. An immunologic hypothesis has been formulated from these results: sex-differential survival of conceptuses during the perinatal period would be due to sex-differential conceptomaternal immunologic interactions. An advantage in survival of the female fetus results from these interactions in primiparous mothers. However, immunologic behavior of the mother is immunologic hypothesis for the sex-differential of perinatal survival has been formulated from these results.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractThis study characterizes the circulatory changes associated with asphyxia in the newborn monkey and examines the effect of phenobarbital on asphyxia. The time to last gasp and duration of total asphyxia as well as heart rate at the start of resuscitation were the same in the phenobarbital-treated and untreated infants. Initial cardiac output was the same in both groups; there was a profound drop in cardiac output with asphyxia which was the same in both groups. Organs which preferentially receive a greater percentage of cardiac output during asphyxia are heart, total brain, and adrenal glands. Organs receiving a decreased percentage of cardiac output during asphyxia are kidneys, liver, and gastrointestinal tract. Cerebral hemisphere flow as a percentage of cardiac output is maintained during asphyxia, whereas paleoencephalon flow as a percentage of cardiac output increases significantly. These data confirm the circulatory redistribution of cardiac output in response to asphyxia described previously in the monkey fetus. The treated infants did not show the prolongation of time to last gasp reported in the monkey fetus; the dose of phenobarbital we used, although adequate to produce sedation, may have been too low to demonstrate the protective effect.SpeculationThe long term survival status of infants with neonatal diseases such as severe meconium aspiration or hyaline membrane disease which are frequently accompanied by varying degrees of asphyxia might be improved by including phenobarbital in the treatment regimen if a protective effect were conclusively demonstrated.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractThree members of a Virginia family with a bleeding disorder were found to have a serum defect in thromboplastin generation similar to the previously reported “Car. factor” deficiency. Sera from three members of the original Car. family did not correct the defect of affected members of the Virginia family. Partial thromboplastin times of Car. deficient individuals and affected members of the Virginia family were normal. Although correction with normal serum is attainedin vitro, the serum defect persisted after infusion of fresh frozen plasma.Platelet function studies of the Virginia family revealed less than 30% aggregation after the addition of exogenous ADP and disaggregation within 2 min. Evaluation of children with Noonan's syndrome, albinism, and “Portsmouth” syndrome showed coexistent platelet aggregation defects and nonspecific serum defects.SpeculationThese studies suggest that the Car, factor is nonspecific; the serum defect may result from the interaction of abnormal cellular elements of the blood during clotting of whole blood in glass. This deficiency can be correctedin vitroby the addition of dilute thrombin.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

ExtractAn indicator-dilution method is described for measuring fetal pulmonary fluid, FPF, volume (Ve), and volume change with time (&OV0312;s) in the lamb fetusin utero.The indicator, albumin, which is the predominant protein of normal FPF, was administered directly to FPF in the form of radio-iodinated human serum albumin (RISA). We have shown that (1) RISA is disbributed homogeneously throughout the FPF compartment, (2) it is not altered within FPF, (3) it does not alter the functional characteristics of FPF, and (4) it remains within the FPF compartment throughout the period of measurement. Ve varies directly with the weight of the fetus so that Ve per kilogram was 31.6–35.6 ml/kg in four of five fetuses. The Ve per kilogram was lower in one fetus at the start of the experiment but increased rapidly to 29.0 ml/kg within 45 min. Thus the relaxation volume of the fetusin uterois in the range of functional residual capacity (FRC) and thoracic gas volume of the air-breathing neonate, which indicates that the pulmonary transformation at birth is, in essence, an isovolumic change in state wherein the fetal liquid-lung becomes the neonatal air-lung. The rate at which FPF is formed (&OV0312;s) is about 1.5 ml/hr-kg; however, the rate may change in so far as both rapid increases and rapid decreases of FPF volume were observed. When breathing movements were induced in the fetus by stimulation of the sciatic nerve, FPF volume decreased rapidly (&OV0312;s = −3.0 ml/hr-kg), which indicates that negative intrathoracic pressures promote its resorption. When FPF volume fell transiently or was low initially, there was subsequent rapid restoration of volume to the range of anticipated FRC.SpeculationValidation of a reliable method for measuring Ve and Vs of FPFin uteroprovides a basis for study of molecular transformations within this compartment during gestation,e.g., our investigation of the fate of FPF phosphatidylcholine in the accompanying report. Since FPF is the analog of the alveolar lining layer of the air-breathing animal, studies of the former (FPF) may give insight into the fluid and molecular dynamics of the latter which, to date, have been quite elusive because the lining layer cannot be sampled directly. Our observation that negative intrathoracic pressure alone seems to promote resorption of FPF under the conditions of our experiments suggests that this may be an important mechanism for the formation of the air-lung at birth. Since relaxation volume of the fetus is practically the same as that of the neonate, we have proposed that alveolar surface tension of the neonate is close to 0.

ISSN:0031-3998    

出版商:OVID    

年代:1975

数据来源: OVID