摘要:

Bronchoalveolar macrophages (BAM) protect the adult lung from low level microbial contamination. The antimicrobial activity of human newborn RAM is unknown. BAM were isolated from effluents of suctioned, intubated newborns and from bronchoalveolar lavage of healthy, nonsmoking adult volunteers. Anin vitrocytologic slide assay was developed and used to ascertain:1) inhibition of intracellular filamentation ofCandida albicans(active yeast growth) and 2) killing + digestion of ingestedC. albicans.The ability to restrict intracellular yeast filamentation was markedly different for human newbornversusadult BAM. Adult BAM were five times more effective in restricting intracellular filamentation of Candida compared to newborn cells (p< 0.01). Nonfilamented ingested yeast were also handled differently by newborn and adult macrophages. Nonfilamented yeast were killed and digested by adult BAM at a rate that was 2.5 times above that noted in neonatal lung macrophages (p< 0.005). However, no differences were found in the total number of killed + digested Candida within human newborn and adult BAM [adult = 32A ± 10.5% (n= 5), newbornn= 8), and newborn >1200 g = 30.2 ± 11.1 % (n= 16), mean ± S.D.]. Neonatal BAM were able to destroyC. albicansat a level equivalent to adult cells because there newborn phagocytes allowed intracellular Candida to enter a state of active growth, thereby rendering the yeast more susceptible to killing and digestion. The anti-Candida activity noted in lung macrophages recovered from normal 1-day-old and adult rabbits was similar to that seen in human BAM. Kinetic studies of intra- and extracellular yeast filamentation with time revealed that extracellular yeast were unrestricted in their ability to grow (filamentation = 98 ± 0.5% by 2 h). Bonchoalveolar macrophages recovered from rabbits exposed to 95 + % O2for 96 h after birth had a 2-fold higher rate of intracellular Candida filamentation when compared to BAM lavaged from newborn rabbits raised in room air [66.3 ± 5.9%versus33 ± 13.5% (mean ± SD,p< 0.025)]. Oxygen exposure did not alter macrophage phagocytosis. We conclude that oxygen therapy may be an important factor underlying the fungistatic limitations of BAM from newborns undergoing intensive care. (Pediatr Res24: 285–290, 1988)

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Elimination of CO2during liquid ventilation is dependent on flow, diffusion, and the liquid's capacitance for CO2. Maximum expiratory flow (Vmax) and diffusion dead space were measuredin vivoin 12 young cuts during liquid fluorocarbon (FC-80) ventilation to determine the effect of breathing frequency on maximum CO2elimination. All animals were maintained (PaO2, = 255 ± 19 SEM mm Hg, PaO2, = 35 ± 1 SEM mm Hg, pH = 7.31 ± 0.01 SEM) within physiologic range during 1–4 h of liquid ventilation. The Vmaxin air (26 ± 1 SEM liter/min) and in liquid (1.2 ± 0.2 SEM liter/min) was determined by volume displacement plethysmography. Diffusion dead space (VDdiff) during liquid ventilation as a ratio of alveolar volume (VA) was well correlated (r= 0.84,p< 0.005) with the average time (tav) the liquid was in the lung [VDdiff/VA= 0.89 e(-0.053 tav)]. Alveolar ventilation, CO2elimination (VCO2and PaCO2were not affected by breathing frequency (f) when tidal volume was adjusted appropriately during steady state liquid ventilation. Predicted maximum CO2elimination (VCO2max) determined from Vmaxand VDdiffwas 24 ml/min at a f of 3–3.5 breaths/min. The maximum was found to be strongly dependent on f with much less dependency on fixed dead space (anatomic plus equipment) and wave shape characteristics. Elimination of CO2decreased at low values of f due to inadequate ventilation and at high values of f due to inadequate diffusion time. From a comparison of experimentally determined steady state VCO2to theoretically predicted VCO2max, the results demonstrate a f-related functional reserve capacity for CO2elimination during liquid ventilation. These findings suggest that by optimizing the liquid ventilatory pattern it should be possible to maintain adequate CO2elimination and physiologic PaCO2in the presence of pulmonary dysfunction and/or elevated metabolic states. (Pediatr Res24: 291–296, 1988)

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

A total of 20 healthy term infants between 4 and 6 months of age were randomly assigned to either a low protein formula (F1.3) containing 13 g protein/100 ml or a high protein formula (F1.8) containing 1.8 g protein/100 ml. Both formulas were isocaloric (72 kcal/100 ml) and had a whey-casein ratio of 50:50. Ten control infants were breast-fed (BF). The mean protein intakes (including supplementary foods) were 1.9 ± 0.3, 2.6 ± 0.2, and 1.3 ± 0.2 g/kg/day, respectively. The mean concentrations of serum urea were 2.8 ± 0.6 (F1.3), 4.1 ± 0.6 (F1.8), and 2.2 ± 0.8 mmol/liter (BF) sit 6 months (F1–3versusBF, NS, F1.8versusBF,p< 0.001). The urine excretion of nitrogen was similar in the F1.3 and BF groups being 81 and 78 mg/kg/day. In the F1.8-group nitrogen excretion was higher, 138 mg/kg/day. Plasma concentrations of albumin, prealbumin, and transferrin were normal and similar in the groups. Weight gain was significantly higher in the F1.8 group, 22.8 ± 1.7 g/kg/wk when compared to the F1.3 and BF groups, 19.9 ± 3.9 and 18.0 ± 4.3 (p< 0.01), respectively. These data indicate that a decreased protein-intake from formula during weaning results in many indices of protein metabolism and growth more similar to those found in BF infants than when conventional follow-up formulas are used. (Pediatr Res24: 297–301, 1988)

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

We determined metabolic responses after enteric galactose alimentation in 5− to 7-day-old newborn rats fasted for 24 h. The glycemic response was attenuated after enteric galactose feeding compared with the response after enteric glucose-fed rat pups.14C radioactivity in blood from galactose-fed pups was reduced as counts in blood galactose were lower than counts in blood glucose in glucose-fed pups. Nonetheless within 15 min, [14C] from galactose appeared in blood glucose suggesting rapid conversion of galactose to glucose. The plasma insulin response was also attenuated after galactose feeding compared with the insulin response after enteric glucose. Hepatic glycogen content increased rapidly after enteric galactose feeding and was higher than after glucose feeding at 60, 120, and 180 min. Significant glycogen synthesis after oral glucose was delayed and occurred at 240 min. Carbon radioactivity in glycogen was higher in galactose fed pups between 15 and 360 min of the study. Serial determination of hepatic metabolites revealed an increase of galactose-1-phosphate levels after oral galactose at 240 and 300 min and a transient decline of ATP at 15 min. Other hepatic metabolites did not demonstrate significant differences between the two groups. These data suggest that hepatic glycogen synthesis is more rapid and occurs sooner after galactose than after glucose alimentation in previously fasted newborn rats. Galactose may enter a more direct pathway for neonatal hepatic glycogen synthesis. The relatively delayed entry of glucose label into hepatic glycogen and the delay of net glycogen synthesis after oral glucose suggest that glucose entry is not direct and may require further metabolism before incorporation into glycogen. Although galactose may replenish fasting neonatal hepatic glycogen content faster than glucose, there is concern over the elevated hepatic galactose-1-phosphate levels and the transient decline of ATP. (Pediatr Res24: 302–307, 1998)

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Human carnitine palmitoyl transferase (CTP) deficiency results in two different clinical variants, one with “hepatic” and one with “muscular” symptoms. We studied CPT activity and long-chain fatty acid oxidation in fibroblast cell fines from four patients, two from each group. Overall CPT activity was deficient in patients' fibroblasts with the hepatic presentation, as previously demonstrated in patients' fibroblasts with the muscular presentation. The hepatic patients' fibroblasts displayed a CPT, deficiency which resulted in impaired long-chain fatty acid oxidation. In contrast, CPT1activity and palmitate oxidation were normal in muscular patients' fibroblasts. In these latter patients, the mutation presumably involved CYT2activity. These data suggest that CPT deficiency is due to at least two different mutations, resulting in two distinct patterns of clinical and biochemical abnormalities. (Pediatr Res24: 308–311, 1988)

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The present study was performed to determine the role of the normal fetal concentration of insulin in regulating placental-fetal glucose exchange. Fetal insulin deficiency was produced by streptozotocin injection into near term fetal sheep, and the effects of this insulin deficiency on net uteroplacental glucose uptake and net umbilical glucose uptake were measured. Each fetus received two or three doses of streptozotocin, 100 mgkg-1dose-1, given on separate days. This dosage of streptozotocin produced a 97.6% reduction in fetal pancreatic insulin content, a fall in fetal plasma insulin concentration (21 ± 2 to 10 ± 1 μUml-1), a rise in fetal plasma glucose concentration (57 ± 4 to 114 ± 19 pgml-1), a rise in fetal blood glucose concentration (20.4 ± 0.9 to 33.4 ± 4.4 mgdl-1), and a failure of insulin secretion in response to glucose infusion. Fetal blood oxygen content and umbilical oxygen uptake were normal and did not change during the entire study. Umbilical glucose uptake was reduced by 66% (5.98 ± 0.38 to 2.02 ± 1.31 mgmin-1kg-1) after the streptozotocin-induced hypoinsulinemia and hyperglycemia but was returned to the control level by an insulin infusion into the fetus that reestablished the control maternal to fetal glucose concentration gradient. Net uteroplacental glucose uptake (consumption) did not change throughout the study. Because glucose concentration and umbilical glucose uptake could be normalized by an insulin infusion, it is unlikely that direct or toxic effects of streptozotocin on fetal or placental glucose metabolism were primarily responsible for the hyperglycemia and the reduced rate of umbilical glucose uptake. Thus, changes in fetal glucose concentration primarily affected umbilical glucose uptake. Furthermore, the failure of the fetus to respond to a glucose infusion after streptozotocin injection with the same rate of exogenous glucose entry (umbilical uptake plus intravenous infusion) measured during the control period glucose infusion indicates that hypoinsulinemia contributed to the fetal hyperglycemia. These results indicate that the normal fetal insulin concentration determines net umbilical glucose uptake by regulating fetal glucose concentration. (Pediatr Res24: 312–317, 1988)

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Atrial natriuretic factor (ANF) is a class of diuretic and natriuretic peptides secreted by mammalian cardiac atria. Although basal plasma ANF levels in the ovine fetus are elevated relative to the adult, fetal secretion of ANF increases in response to intravascular isotonic saline infusion. Recentin vitroandin vivostudies indicate that ANF secretion also may be stimulated by increased plasma osmolality and/or sodium concentration. The present studies were conducted to determine if volume expansion associated with increased plasma osmolality would further augment ANF secretion in the ovine fetus. In response to successive 30-min intravenous infusions of 3% saline at 0.5 and 1.0 ml/kg/min fetal plasma ANF significantly increased from a basal level of 98 ± 31 pg/ml to a peak of 439 ± 42 pg/ml (p< 0.05). During a 30-min postinfusion recovery period, fetal plasma ANF significantly decreased from peak values to 224 ± 10 pg/ml (p< 0.05), although remaining above basal levels. Fetal plasma osmolality significantly increased from 300 ± 2 mosmol to 325 ± 3 mosmol (p< 0.05) whereas fetal plasma arginine vasopressin increased from 1.9 ± 0.4 to 10.9 ± 7.0 pg/ml (p< 0.05) at the conclusion of the 3% saline infusion. During the saline infusion a significant increase in fetal heart rate and decrease in fetal hematocrit were noted. Fetal blood pressure and maternal plasma ANF and arginine vasopressin concentrations remained unchanged. Despite the potential stimulatory effects of hyperosmolality, increased plasma arginine vasopressin, and intravascular volume expansion, the increase in fetal plasma ANF in the present study did not exceed that induced by isotonic saline alone. These results suggest that plasma osmolality does not act additively with intravascular volume loading for stimulation of ANF secretion in the ovine fetus. (Pediatr Res24: 318–321, 1988)

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Calcium concentration in fetal lung fluid in lambs is relatively low, about 1.0 mEq/liter, and its concentration in alveolar fluid in mature rabbits is about 3 mEq/liter. To see if the Ca++concentration changes at birth, we measured alveolar Ca++as soon as possible after delivery by cesarean section and the onset of ventilation in eight anesthetized lambs at 144 days gestation. Subpleural alveoli were punctured with Ca++selective microelectrodes as soon as 4 min and as late as 220 min after the onset of mechanical ventilation. The [Ca++] was 1.2 ± 0.2 mEq/liter (mean ± SD,n= 8) in fetal lung fluid collected before ventilation. After about 25 min of ventilation, alveolar Ca++was not different from that in term lambs 24 to 72 hold (3.3 ± 0.6 mEq/liter,n= 8). The [Ca++] increased with a t1/2of about 10 min. Thus, alveolar Ca++assumes a mature character very rapidly after the start of breathing in term lambs. (Pediatr Res24: 322–325, 1988)

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Metallothionein, a high cysteine-containing protein, can bind with both essential and nonessential metals and thus play an important role as a metal storage protein and also in the detoxification of toxic metals. Although in the human fetus, levels of trace minerals and metallothionein are very high, their postnatal changes are not well documented. The purpose of the present investigation, therefore, was to quantify the accumulation of metallothionein in premature and full-term infants during the first year of life and to identify factors affecting its accumulation. From 47 postmortem samples, it was determined that hepatic metallothionein levels were highest in newborn premature and full-term infants falling to levels found in older children by 4.4 months of age. Hepatic zinc levels were also highest in the youngest infants, falling with increasing postnatal age. There was a significant positive correlation between zinc and metallothionein at all ages. However, there was a negative correlation between hepatic metallothionein levels and cystathionase activity. Hepatic copper and metallothionein levels were unrelated. The renal concentration of metallothionein, zinc, and copper were significantly lower than corresponding hepatic levels. The fall in hepatic levels of zinc and metallothionein during the first months of life correspond to a period of negative zinc balance and low endogenous cysteine production in the newborn. Thus metallothionein may play an important role as a storage depot for these two essential nutrients during this critical period of active growth. (Pediatr Res24: 326–329, 1988)

ISSN:0031-3998    

出版商:OVID    

年代:1988

数据来源: OVID