摘要:

Since kernicteric lesions are usually found in the subcortical regions of the brain and these areas also receive the highest blood flow during asphyxia and hypercapnia, we hypothesized that increases in brain bilirubin deposition may be related to increases in brain blood flow. Fourteen piglets underwent a 3-h infusion of bilirubin to maintain total serum bilirubin at approximately 8 mg/dl, during which time blood gases, hemodynamic variables, and brain blood flow were determined. After sacrificing the animals, regional brain bilirubin content was determined. Ten piglets underwent the same protocol; in addition, hypercapnia was induced during the last hour of study (Paco2 approximately 70 mm Hg). The regional brain blood flow and bilirubin deposition were significantly increased over control values (p < 0.05) following hypercapnia in the subcortical region and significantly so in the midbrain and cerebellum. In separate groups of control (n= 6) and hypercapnia (n= 6) piglets,125I-labeled albumin was infused and demonstrated that hypercapnia was not associated with increased regional brain albumin content. We conclude that hypercapnia-induced augmentation in regional brain blood flow is associated with increased deposition of unbound bilirubin. Although the causal relationship between these two observations has not been firmly established, the findings deserve future investigation to clarify the role of brain blood flow, brain bilirubin deposition, and the production of kernicterus in high risk infants.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

An association between zinc depletion and intrauterine growth retardation might occur through disturbed prostaglandin (PG) synthesis. The zinc content and PG metabolism of leucocytes from control, nonpregnant women and mothers 24–48 h after delivery, were measured and related to fetal growth and maternal smoking. Mothers of small for gestational age babies had lower polymorphonuclear and mononuclear cell zinc contents than mothers of appropriate for gestational age babies or nonpregnant controls. Monocytes were the major leucocytes producing PGs. Mothers of small for gestational age babies had higher PGE2:F2aratios than mothers of appropriate for gestational age babies. PGF2aproduction and PGE2a:F2aratio were correlated with tissue zinc status. Monocytes from nonsmokers tended to produce more PGs than those from smokers but the differences were not significant. Mild maternal zinc depletion is not significantly sufficient to alter absolute PG production, but is associated with altered differential production of PGs in human leucocytes. Zinc depletion or malnutrition may contribute to intrauterine growth retardation by affecting placental and/or umbilical PG production.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The transfer and metabolism of L-carnitine. L-acetylcarnitine, and L-palmitoylcarnitine were studied in the human placenta at term by means ofin vitrodual perfusion of a placental lobe. L-Carnitine transfer was 20% that of the freely diffusing antipyrine and 40% that of L-lysine. The transfer of L-acetylcarnitine was similar to that of L-carnitine, but no placental transfer of L-palmitoylcarnitine was found. In contrast to L-lysine, L-carnitine, and L-acetylcarnitine were not actively transported from the maternal to the fetal circulation. No stereospecific transfer of carnitine across the placenta was found. However, there was stereospecific uptake of carnitine by placental tissue. The placenta exhibited an active carnitine metabolism by esterifying free carnitine and hydrolyzing carnitine esters taken up from the perfusion medium and releasing the metabolites into the fetal and maternal circulations.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Newborn infants and animals typically exhibit a paradoxical ventilatory response to hypoxia. The depressive phase of the response has not been adequately explained. It has been suggested that hypoxia may cause the release of inhibitory neuromodulators which depress ventilation. We have postulated that the nucleoside, adenosine, may be involved because 1) it is rapidly released during hypoxia, 2) it depresses ventilation, and 3) theophylline, a competitive inhibitor, has successfully been used to treat apnea of prematurity. Herein we describe the effects of aminophylline on ventilation during hypoxia in the spontaneously breathing newborn piglet administered both rapidly after ventilatory depression has occurred (bolus) and before the onset of hypoxia (pretreatment). Ten percent oxygen breathing produced a typical biphasic ventilatory response. The decrease in minute ventilation was caused by a decrease in both tidal volume and respiratory frequency. The bolus administration of aminophylline reversed the depression in minute ventilation (p < 0.001) by increasing tital volume (p< 0.002). Pretreatment with aminophylline decreased the amount of ventilatory depression (p< 0.05) by preventing a decrease in respiratory frequency. We conclude that aminophylline, an adenosine antagonist, reduces the decrease in ventilation which occurs during hypoxia in the newborn. We speculate that adenosine may play a role in hypoxic ventilatory depression and respiratory control in the newborn.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Saliva secretion induced by 10−6M acetylcholine was reduced 74% in isolated, perfused submandibular glands of control rats when the gland was perfused with solutions containing either furosemide (10−3M) or sulfate (instead of chloride) as the major anion. In regular (Cl-containing) perfusates without furosemide, saliva secretion was reduced 74 % in isolated glands of rats treated with seven intraperitoneal doses of reserpine (0.5 mg/kg body weight). In the latter, addition of furosemide or replacement of perfusate Cl−with SO=caused a further 35% drop in saliva volumes. Salivary Cl−concentrations were lower in saliva from the treated animals and were reduced further by furosemide, which also reduced the Cl−concentrations of control saliva. In submandibular acini isolated from control glands, acute exposure to36Cl (1 μCi/ ml) resulted in a rapid uptake of tracer so that a constant content of isotope (approximately 9.5 nM/mg protein) was attained in 4–5 min and maintained for 30 min. This basal uptake reached 8.4 nM/mg protein in acini isolated from glands of reserpine-treated rats and attainment of a steady state of tracer content was delayed and required 8–10 min. Exposure to acetylcholine reduced uptake and steady state tracer content by 35% in control acini, but had no effect in acini of reserpine-treated rats. Acetylcholine caused a rapid decrease (42% in 1 min) in36CI content of control acini which were preloaded with tracer for 12 min, but only a 23% decrease in acini of reserpine-treated rats. Exposure to furosemide at zero time caused a 50% reduction in36Cl uptake in control acini and a 41% reduction in acini of the treated animals. Addition of the diuretic to acini preloaded with tracer caused a slower reduction in36Cl content of control acini (48% in 7 min) and a similarly slow and smaller reduction (26%) in acini of reserpine-treated rats. These findings indicate that: 1) Salivary fluid secretion requires the transepithelial movement of CI−in salivary acinar cells. This involves both entry of Cl−, which occurs in part by a furosemide-sensitive transport system, and efflux of CI. 2) Both steps of this mechanism are abnormal in salivary glands of reserpine-treated animals. Cl−uptake is delayed and shows a somewhat reduced sensitivity to furosemide, while Cl−efflux is inhibited. The resulting decrease in overall transepithelial Cl−transport can explain, therefore, the reduced saliva secretion observed in reserpine-treated animals. 3) Since the reserpine-treated rat has been used as an animal model for cystic fibrosis, similar abnormalities in Cl−transport could exist in salivary cells of patients with this disease and, similarly, explain the reported disturbances in saliva secretion.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

In order to determine if defects in regulation of immune responses play a role in the pathogenesis of croup, we studied 37 infants and children with either croup or upper respiratory illness alone due to parainfluenza virus (PV). PV-specific IgE responses were determined by an enzyme-linked immunosorbent assay, cell-mediated immune responses to PV antigen were studied byin vitrolymphocyte transformation assays, and suppressor cell function was determined by addition of histamine to lymphocyte transformation assays. In comparison to patients with upper respiratory illness alone, patients with croup had increased production of PV-specific IgE antibody, increased lymphoproliferative responses to PV antigen, and diminished histamine-induced suppression of lymphocyte transformation responses to PV. These results suggest that a defect in suppressor function exists among croup patients. Similar defects have been demonstrated in bronchiolitis and atopic diseases, providing an immunologic link between the three illnesses.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The compromised human newborn frequently presents with overwhelming feeding problems which lead to inadequate intake. These problems may affect the development of the small intestine, especially mucosal barrier function, leading to increased infections and susceptibility to allergens. To study this, an animal model was established using neonatal rabbits deprived of nutrients from birth until 72 h. Mucosal barrier function was compared in deprived and control (naturally fed 72-h-old animals) rabbits by measuring immunoreactive bovine serum albumin in serum 4 h after intragastric infusion of crystalline bovine serum albumin (200 mg/100 g body weight). Trypsin activity was measured in rinse fluid obtained from the small intestine. Representative sections of jejunum from control and experimental animals were formalin fixed and stained with hematoxylin and eosin for morphologic comparison. Following the bovine serum albumin feeding, a significantly increased serum immunoreactive bovine serum albumin and significantly decreased trypsin-like activity of the small intestinal rinse fluid was noted in starved animals compared to controls. In addition, the enterocytes of malnourished animals were more cuboidal and contained fewer and smaller supranuclear granules on microscopic examination than the enterocytes of controls. This study suggests that short-term starvation in newborns affects mucosal barrier function. Acute starvation may place newborns at increased risk for infections and allergic disease.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

We injected 3-day-old (neonatal), 8-day-old (infant), and 8-wk-old (adult) Sprague-Dawley rats with monocrotaline to examine the effect of a toxic agent at various stages of lung development. Two and four weeks after injection the rats were killed and the heart and lungs removed: the right and left ventricles were separated and weighed, the pulmonary artery was injected with barium-gelatin, and the lung was fixed in the inflated state. Morphometric techniques were applied to assess lung volume, alveolar size and number, and arterial size, muscularity, and concentration relative to alveolar. Rats injected with monocrotaline in the neonatal period did not survive to 3 wk. After 2 wk, there was no significant right ventricular hypertrophy and pulmonary vascular changes were no worse than in the other rat groups injected with monocrotaline, but alveolar development was severely impaired; less than one-third the normal number was present. Rats injected with monocrotaline in infancy had normal alveolar development. After 2-wk, the arterial changes,i.e.extension of muscle into peripheral arteries, medial hypertrophy of muscular arteries, and decreased arterial concentration relative to alveolar were similar to those observed in adult rats. After 4 wk, there was a decrease in medial hypertrophy associated with growth in artery size and only a lack of regression of right ventricular weight. In adult rats, after 4 wk medial hypertrophy became progressively more severe, the arterial concentration relative to alveolar decreased further, and right ventricular hypertrophy developed. Thus, exposure to a toxic agent in the newborn period may have a critical effect on alveolar development, whereas arterial changes induced by a toxic agent during infancy may regress if there is potential for growth of the pulmonary vascular bed.

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1985

数据来源: OVID