摘要:

SummaryPulmonary mechanics were studied with the constant pressure body plethysmograph method in 78 infants during the first year of life. Registrations of breathing frequency, tidal volume, minute volume, dynamic compliance, pulmonary functional resistance, and end-expiratory resistance were made at rest and during carbon dioxide-induced hyperventilation. Data from 70 infants demonstrated strong correlations (P< 0.001) between all pulmonary function parameters and length. Carbon dioxide-induced hyperventilation was achieved mainly by an increased tidal volume. Pulmonary functional resistance did not change with hyperventilation, indicating wider airways during forced ventilation.A special breathing pattern called “subclinical grunting” was found in 16 of 45 infants who were low birth weight but without clinical signs of hyaline membrane disease. The pattern was characterized by a high resistance during most of the prolonged expiration. It was identical to that previously described in cases of hyaline membrane diseases. All re-examined low-birth-weight infants with subclinical grunting developed a normal breathing pattern.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SummaryWe investigated with anin vivosingle-pass perfusion technique net secretion of calcium, magnesium, and zinc from proximal and distal small intestinal segments and from the cecum plus colon segments of suckling, weanling, and adolescent rats during perfusion with either isotonic (300 mOsm/kg) or hypertonic (500 mOsm/kg) mineral-free solutions. There was net secretion of calcium, magnesium, and zinc in all segments perfused at all age periods.During isotonic perfusion, rates of net secretion of calcium and zinc were severalfold greater in the proximal and distal segments of the suckling rats compared with the corresponding segments of the adolescent rats. Net magnesium secretion was similar in the suckling and adolescent rats. Net secretion rates for the weanling rats tended to be intermediate. During hypertonic perfusion, net secretion rates for calcium, magnesium, and zinc were severalfold greater from all segments of the suckling rats compared with the corresponding segments of the adolescent rats. During either isotonic or hypertonic perfusions, rates of net secretion of calcium and magnesium in general were greater from the proximal and distal segments than from the cecum plus colon in the suckling and weanling rats. In contrast, for the adolescent rats, net secretions from all segments in general were similar. For zinc, rates of net secretion were somewhat greater in the cecum plus colon of rats in all age groups.Our findings suggest a greater permeability of the intestinal epithelium, not only to water and electrolytes but also to certain minerals (calcium and magnesium) and trace elements (Zn) in suckling rats compared with adolescent rats. The implication is that during periods of osmotic diarrhea, infant animals appear to be at risk for losing excessive amounts of minerals and trace elements. These findings may have clinical relevance to human infants suffering from recurrent diarrheal diseases.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SummaryThe cytosol peptidase activities hydrolyzing glycyl-L-leucine and L-leucyl-glycyl-glycine as well as the activities of the brush border peptidases (oligoaminopeptidase, aminopeptidase A, γ-glutamyl-transpeptidase, dipeptidyl-aminopeptidase IV, and carboxypeptidase) are present in rat fetuses during the early differentiation of the intestine (17th to 19th days of fetal life); they increase then at a different rate, reaching a maximum at various times, in the second and third wk after birth, and then decrease to the adult values during the first month of postnatal life. Only the oligoaminopeptidase activity increases steadily after birth, reaching maximal activity in the last decade of the first month.In human fetuses aged between 8 and 22 wk, the γ-glutamyl-transpeptidase was the only brush border peptidase found to be higher than in adults and children. On the other hand, the amino-peptidase A is remarkably reduced. The dipeptidylaminopeptidase IV and the carboxypeptidase are already at adult level in the youngest fetuses, and the oligoaminopeptidase increases during the period of fetal life studied; at the end of this period, the enzyme activity does not differ from the values found in children and adults.The small intestine of the term and preterm newborn should, therefore be able, with some possible exceptions, to efficiently digest peptides.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SummaryIt is well known that corticoids act to induce fetal lung maturation when administered to the fetus or mother. However, their physiologic role has been recently questioned with regard to stimulation of surfactant production.We investigated the process of fetal lung maturation to determine whether or not it is associated with changes in amniotic fluid cortisol.Sixty-two amniotic fluid samples from 53 patients were obtained by transabdominal amniocentesis strictly due to maternal and/or fetal clinical indication, according to the course of pregnancy and the maternal and/or fetal status.The L/S ratio was measured on thin-layer plates by reflectance densitometry and calculated as previously described by Glucket al.Cortisol levels in amniotic fluid were measured by radioimmunoassay using commercial reagent kits (Gamma coat I125cortisol; Clinical Assays, Inc.).The level of amniotic fluid cortisol increased with gestational age from wk 30 to 41; a sharp increment was observed at 39 to 41 wk.No significant differences were found when the mean values of cortisol were compared at wk 30 to 32, 33 to 35, and 36 to 38. When the fourth group was included (39 to 41 wk), a statistically significant difference was found (F= 4.63;P< 0.01).There was a progressive increase in L/S ratio during gestation as has already been described, plus a value greater than 2 was found during the 33 to 35 wk period. The statistical analysis performed on L/S ratios at weekly intervals 30 to 32, 33 to 35, and 36 to 38 showed a significant difference in the mean values in the groups studied (F= 6.84;P< 0.005).Therefore, the increment of L/S ratio over 2 was already observed during the 33 to 35 wk period of gestation, whereas the mean cortisol amniotic fluid values remained unchanged between the 30th and the 38th wk. The cortisol peak was observed only during the 39 to 41 wk period.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SummaryTo examine the dose-response relationships of oxygen-induced lung changes, newborn rats were exposed to various patterns of concentrations of hyperoxia (0.4, 0.8, and >0.95 FiO2) for up to 12 days. Prominent findings included microscopic evidence of lung injury and retarded alveolar development (secondary septal development delayed by as much as 88%), lower whole lung DNA (50% of control), lung-to-body-weight ratios (by as much as 18%), and significantly less compliance in the lungs after exposures of 6− or 12-day durations to all concentrations of hyperoxia. Significant increases in the activities of the lung protective enzymes superoxide dismutase (129 to 160% of control), catalase (112 to 274% of control), and glutathione peroxidase (118 to 256% of control) were noted when activity was expressed on a DNA basis after 12-day exposures to the various patterns of hyperoxia.Lung changes noted after a 7-day recovery period in air included interstitial thickening (117% of control), persistance of the microscopic injury, and retarded alveolar development seen immediately after initial 6-day hyperoxic exposures. At the conclusion of a second wk of recovery in air, the lungs of hyperoxic exposed animals resembled controls in most respects, but a significantly altered compliance was exhibited by the lungs of animals initially exposed to 6 days of 0.4 or >0.95 FiO2.The dose dependency of oxygen-induced lung injury is complex. Straightforward, stepwise dose-response adequately describes the evolution of microscopic injury and slowing of alveolar development in hyperoxia, but the dose dependency is not as clearly identified in the oxygen-induced retardation of lung growth including DNA content and in changes in antioxidant enzyme activities. Changes in lung compliance clearly do not follow expected dose-response relationships.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SummaryJaundice phototherapy is associated with a significant incidence of watery diarrhea. We have postulated that acute intestinal secretion, rather than malabsorption of dietary carbohydrate, is an effect of a photoproduct of bilirubin upon the intestinal mucosa. Because a major effect of phototherapy is the hepatic excretion of nonconjugated bilirubin, we investigated the effect of bilirubin on small intestinal function in the hamsterin vivo.The entire small intestine was luminally perfusedin vivowith solutions containing bilirubin (0.125 to 0.75 mmole/liter) and net water and sodium fluxes were measured. Control animals absorbed both water (JnetH2O = 58.9 μl/min/g) and sodium (JnetNa= 4.55 μEq/min/g), but animals perfused with bilirubin (≥0.25 mmole/liter) exhibited secretion of water (JnetNa= −39.0 - −85.9) and sodium (JnetNa= −9.91 - −18.24). The rate of water secretion was positively related to the concentration of bilirubin in the infusate (r= 0.749;P< 0.001). The concentration of bilirubin in ultrafiltrates of perfusate was likewise positively related to its concentration in the infusate (r= 0.844;P< 0.001), indicating the potential importance of soluble forms of bilirubin in inducing secretion. Possible epithelial injury was studied by measuring the concentration of DNA in the perfusate and the activity of disaccharidases in postperfusion mucosa, and the possible role of cyclic adenosine monophosphate as a mediator of the secretory process was investigated by determining its concentration in postperfusion mucosa. Perfusion with 0.5 mM bilirubin, which produced significant secretion, did not cause loss of DNA (0.284versus0.244 mg/liter) or mucosal lactase activity (56versus53 units/g) or enhancement of cyclic adenosine monophosphate concentration (14.9versus14.12 pmoles/mg protein).

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SummaryTwenty-five preterm newborns were given bolus infusions of sodium heparin (100 units/kg) and plasma heparin levels were assayed at 5, 20, 40, 90, and 150 min. Eight normal adults received a 75 units/kg bolus of heparin and levels were assayed at 5, 30, 60, 120, 180, and 240 min. In comparison with the adult data (mean adult plasma heparin half life (T1/2) = 63.3 min), the newborn infants demonstrated a significantly shorter plasma heparin half life (T1/2 = 35.5 min in group I, 33 to 36 wk gestation; 35.5 min in group II, 29 to 32 wk gestation; and 41.6 min in group III, 25 to 28 wk gestation), as demonstrated by a chromogenic heparin assay. The newborn groups had a larger volume of distribution (Vd) of heparin which varied inversely with gestational age (Vd= 36.6 ml/kg in the adults, 57.8 ml/kg in group I, 73.3 ml/kg in group II, and 81.0 ml/kg in group III babies. Heparin clearance (Cl) was significantly greater in all newborn groups when compared with the adult (ClAdult= 0.43 ml/kg/min; ClGrI= 1.37 ml/kg/min; ClGrII= 1.43 ml/kg/min; and ClGrIII= 1.49 ml/kg/min). A one-stage clotting assay for heparin generated similar results, although infant plasma heparin levels were slightly higher by this assay. Before heparin administration, the mean antithrombin III antigen (AT-III Ag) of the babies was 26.5% of normal adult and was not further decreased 90 min after the heparin bolus.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SummaryLittle information is available on the effect of visible light from commercial fluorescence lamps, commonly used in the treatment of neonatal hyperbilirubinemia, on parameters related to genetic damage in eucaryotic cells. The present study was undertaken to determine whether or not visible light of different wavelengths had any differential effects on the frequency of DNA breaks (frank breaks plus alkaline labile lesions), DNA replication, frequency of sister chromatid exchanges, and survival in cultured Chinese hamster cells.The results revealed that the “blue” spectral band (420 to 500 nm) is mainly responsible for DNA breaks, sister chromatid exchanges, and lethality induced by fluorescent light. This band is precisely that which bilirubin heavily absorbs and, hence, is the most efficient for the decomposition of this metabolite.These results were obtained with the use of light doses of 5 to 30 X 104J/m3versusthe light doses of the order of 100 X 104J/m2being received by infants undergoing phototherapy treatment.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SummaryBody water content and distribution were determined in 16 children aged 2 wk to 28 months before and after open-heart surgery for correction of congenital cardiac defects. Operative procedures were performed using hypothermia and extracorporeal oxygenation. On the day before and the day after surgery, total body water was estimated as the antipyrine space (APS); extracellular water, as the corrected bromide space (CBS), and plasma volume, as the 10-min T-1824-albumin space. Intracellular water (ICW) was assumed to be the difference between APS and CBS; interstitial water was calculated from plasma volume and CBS. Before initiation and after completion of extracorporeal circulation, a pectoral muscle biopsy was performed, and a blood sample was obtained. Muscle total water (TW) content was determined by desiccation, extracellular water (ECW) was estimated as the corrected chloride space, and ICW was assumed to be the difference between TW and ECW. Plasma sodium, potassium, chloride, glucose, and osmolality contents were determined by routine methods. All studies were not completed in all patients.Although APS and CBS increased in eight of 11 children, mean APS (± S.E.) before and after surgery (662 ± 28.0versus714 ± 37.2 ml/kg) and mean CBS (335 ± 30.5versus358 ± 15.5 ml/kg) were not statistically different. Mean ICW changed neither in relation to body weight (328 ± 28.0versus355 ± 34.2 ml/kg) nor in relation to APS (ICW/APS ratio = 0.48 ± 0.040versus0.49 ± 0.010). Neither mean PV (54 ± 4.0versus56 ± 2.8 ml/kg) nor mean blood volume (92 ± 5.4versus90 ± 5.5 ml/kg) changed significantly. Mean interstitial water increased by 9 to 68% over preoperative values in all but one patient (238 ± 10.4versus305 ± 13.4 ml/kg;P< 0.01).Muscle composition was not affected by the procedure. Mean TW was 79 ± 1.3 ml/100 g before extracorporeal circulation and 78 ± 0.8 ml/100 g afterwards whereas ECW averaged 32 ± 4.4 and 36 ± 3.4 ml/100 g, and ICW averaged 48 ± 4.6 and 42 ± 2.9 ml/100 g. Mean ICW/TW ratios were 0.60 ± 0.055 and 0.54 ± 0.040 ml/100 g.Although mean plasma sodium (142 ± 3.5versus139 ± 2.4 mEq/liter) and potassium (3.3 ± 0.16versus3.6 ± 0.15 mEq/liter) concentrations did not change appreciably during extracorporeal circulation; mean plasma chloride content decreased (108 ± 2.9versus100 ± 2.0 mEq/liter;P< .002). Plasma glucose averaged 60 mg/dl more at completion of the procedure, increasing from a mean of 223 ± 25.6 mg/dl to a mean of 283 ± 5.3 mg/dl (P< 0.05). Plasma osmolality increased in five of eight children, but mean osmolalities were similar before and after extracorporeal circulation (301 ± 8.9versus303 ± 5.4 mOsm/kg).These data suggest that a child's organism does not react complacently to the invasive procedures associated with open-heart surgery. Further research into effects of these procedures and into means of minimizing undesirable homeostatic disturbances is warranted.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

SummaryThe effect of various lipids, proteins, and other substances on the adsorption rate of dipalmitoyl phosphatidylcholine (DPC) was investigated. Each substance was added to a sonicated suspension of DPC in saline, and the surface pressure of the adsorbed surface film was measured using a platinum plate suspended from an electrobalance. Pure DPC adsorbed very slowly, being complete only after 8 hr; its half-adsorption time was 91.8 ± 8.3 min. Four additives markedly reduced the half-adsorption time of DPC: dipalmitoyl phosphatidylglycerol (1.1 ± 0.2 min), phosphatidylinositol (2.8 ± 0.4 min), serum high-density lipoprotein (1.0 ± 0.2 min), and surfactant apoprotein (0.9 ± 0.1 min). The half-adsorption times of mixtures of DPC and the other additives ranged from 15.3 ± 1.9 to 107.8 ± 12.1 min.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID