摘要:

To gain information about the ontogeny of neonatal biliary physiology, we determined gallbladder bile composition, hepatic bile flow and composition, and the choleretic effects of taurocholate, taurodehydrocholate, secretin, and glucagon in anesthetized puppies of 0-3 (n=13), 7-21 (n=9), and 28-42 (n=8) days of age, and in fed (n=4) and fasted (n=4) adult dogs. Although gallbladder bile volume was similar in all puppies, chloride concentration in gallbladder bile declined with age (54.2, 33.2, 22.6, 15.9, and 5.8 mEq/liter in these respective groups), and so did bicarbonate concentration (43.5, 26.1, 17.6, 11.4, and 5.7 mEq/liter). In contrast, the concentrations of sodium (175.4, 189.2, 224.5, 251.6, and 279.4 mEq/liter) and bile acids (77.8, 137.3, 206.2, 219.6, and 280.7 mEq/liter) increased. Spontaneous bile flow rate in 0- to 3-day-old puppies averaged 0.194 µl/min/g and increased to 0.365 µl/min/g in puppies of 28-42 days of age. The latter value was not significantly different from that in fed adult dogs (0.344 µl/min/g).14C-erythritol bile-to-plasma ratio in spontaneously secreted bile increased with age (1.05, 1.08,1.26, 1.48, and 1.70), and chloride concentration decreased (96.8, 85.8, 79.2, 74.3, and 60.1 mEq/ liter). The choleretic activity of taurocholate (2 µmol/min/ kg) was the same in all puppies (7.8 µl/jumol) and adult animals (7.2 µl/fimoY). Taurodehydrocholate (2 µmol/min/ kg) increased bile flow by a greater magnitude, yet its choleretic activity in the puppies (13.3 µl/jtmol) was the same as that in adult dogs (12.7 µl/µmol). In all animals, total bile acid excretion accounted for 70-95% of the infused taurocholate or taurodehydrocholate. Secretin (1- 20 CU/kg/h) and glucagon (1-20 µg/kg/h) produced a minimal, or no effect on bile flow in 0- to 3-day-old puppies. In puppies of 28-42 days of age, the choleretic effect of these hormones was 30-45% of that seen in adult animals. These findings suggest that gallbladder and ductular bile water reabsorption, canalicular secretion, and hormone choleresis are all deficient processes in the newborn puppy and develop during postnatal life.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Serum immunoreactive cationic trypsinogen levels were determined in 99 control subjects and 381 cystic fibrosis (CF) patients. To evaluate the status of the exocrine pancreas all CF patients had previously undergone fecal fat balance studies and/or pancreatic stimulation tests. Three hundred fourteen CF patients had fat malabsorption and/or had inadequate pancreatic enzyme secretion (pancreatic insufficiency) requiring oral pancreatic enzyme supplements with meals. Sixty-seven CF patients did not have fat malabsorption and/or had adequate enzyme secretion (pancreatic sufficiency) and were not receiving pancreatic enzyme supplements with meals. Mean serum trypsinogen in 99 control subjects was 31.4 ± 14.8 µg/liter (± 2 SD) and levels did not vary with age or sex. In CF infants (< 2 yr) with pancreatic insufficiency, mean serum trypsinogen was significantly above the non-CF values (p<0.001). Ninety-one percent of the CF infants had elevated levels. Serum trypsinogen values in the pancreatic insufficient group declined steeply up to 5 years, reaching subnormal values by age 6. An equation was developed which described these age-related changes very accurately. Only six CF patients with pancreatic insufficiency had serum trypsinogen levels above the 95% confidence limits of this equation. In contrast, there was no age related decline in serum trypsinogen among the CF group with pancreatic sufficiency. Under 7 yr, serum trypsinogen failed to distinguish the two groups. In those over 7 yr of age, however, serum trypsinogen was significantly higher than the CF group with pancreatic insufficiency (p<0.001), and 93% had values within or above the control range. In conclusion, serum trypsinogen appears to be a useful screening test for CF in infancy. Between 2 and 7 yr of age this test is of little diagnostic value. After 7 yr of age, serum trypsinogen can reliably distinguish between CF patients with and without pancreatic insufficiency.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

In vitroexperiments were performed to examine the contractile responsiveness of guinea pig gallbladder smooth muscle as a function of developmental age. Gallbladder muscle strips from preterm (day 50-55 gestation), newborn (days 1-3 post partum), and 1-month-old animals were stimulated with agonists that initiate the contractile process either by activation of membrane receptors (acetylcholine and the octapeptide of cholecystokinin) or by membrane depolarization (potassium). Dose-response curves were constructed for each agonist in each age group and analyzed with respect to the maximal force developed and the pD2value (negative logarithm of the dose of agonist which produces a one-half maximal response). The results can be summarized as follows: 1) when normalized for tissue cross-sectional area, the magnitude of the contractile response to each agonist increased with increasing developmental age; 2) the dose of agonist required to elicit a one-half maximal response was independent of developmental age. The data indicate that cholinergic and cholecystokinin receptors are present and functional on gallbladder smooth muscle prior to birth and that the force generating capacity of the tissue continues to develop after birth. A reduced contractility of the gallbladder in preterm and newborn animals as compared to young adults may partially explain the decreased choledochol bile flow seen in the neonate.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Eleven normal term infants undergoing respiratory assessment involving rebreathing to produce progressive hypercapnia were studied by Doppler ultrasound examination of an anterior cerebral artery during the procedure. A linear increase in end tidal carbon dioxide concentration from 4.5% to a maximum of 8.5% was documented during a period of 4-5 min rebreathing. A corresponding elevation of transcutaneous carbon dioxide tension was shown in the two infants monitored in this way. In all cases the Pourcelot index fell with rising end tidal carbon dioxide concentration. This fall in Pourcelot index was due to an increase in the diastolic frequency of the Doppler waveform. These results are consistent with the view that Pourcelot index correlates with cerebral vascular resistance distal to the site of recording.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

A stable isotope dilution method was developed to measure accurately small amounts of isovalerylglycine in amniotic fluid and urine for the prenatal diagnosis of isovaleric acidemia. [4,4,4-D3]Isovalerylglycine was synthesized and used as an internal standard. Samples were extracted, methylated, and analyzed by chemical ionization gas chromatography-mass spectrometry operated in the selected ion monitoring mode. This method is very sensitive (lower limit ~5 ng/ml), linear over three orders of magnitude above 10 ng/ml up to at least 10 µg/ml and reproducible. No isovalerylglycine was detected at all in amniotic fluids from eleven normal pregnant women with an exception of a single case which contained 6 ng/ml. Amniotic fluids from five pregnancies at risk were analyzed. Two of these samples had isovalerylglycine concentrations of 957 and 556 ng/ml. Three others contained 18, 18, and 17 ng/ ml of isovalerylglycine. Postpartum diagnostic tests and/orin vitroassay of isovaleryl-CoA dehydrogenase of [1-14C] isovaleric acid oxidation using amniocytes confirmed that the first two fetuses were affected by isovaleric acidemia, whereas the latter three were unaffected. The method described in this report provides a highly accurate and reliable technique for the prenatal diagnosis of isovaleric acidemia.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The effect of breast-feeding on the development of lymphocyte responsiveness in infants has been studied. Peripheral blood mononuclear cells from 15 breast- and 15 bottle-fed infants were obtained sequentially between 6 days and 9 months of age. A number of agents were used to stimulate the cellsin vitroand the resulting proliferative responses were compared between the two feeding groups. A hanging drop microculture system using serum-free medium, enabled spontaneous proliferation and proliferative responses to several stimuli (T and B cell mitogens, allogeneic lymphocytes, and antigen) to be studied at a range of cell concentrations and days of culture. Significant age-related differences were found between the responses of cells from the two feeding groups. Spontaneous proliferation and proliferative responses to the T cell mitogen phytohaemagglutinin and the antigen tetanus toxoid were significantly greater in the breast-fed group at the two earliest ages studied (6 days and 6 wk). Responses to mitogens which predominantly affect B cells, such as pokeweed mitogen andStaphylococcus aureus(Cowan), were similar in both feeding groups at this age. In contrast, from 3 to 9 months of age, responses of cells from bottle-fed infants were significantly greater to all stimuli than responses from breast-fed infants. One possible explanation for the higher level of proliferation by cells from newborn breast-fed infants, is that these infants may absorb the cell-growth factors and lymphokines known to be present in human colostrum and milk. These factors may stimulate T cells and/or their precursorsin vivo. The subsequent greater responsiveness of peripheral blood mononuclear cells from the bottle-fed group at 3 to 9 months of age appears to be due to a higher level of antigenic stimulation in vivo in this group. This could result from the greater intake of cow milk proteins or from the absence of the passive protective effect of the antimicrobial components in human milk.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Thyroxine (T4) administration in mice during the 2nd wk of postnatal life elicits a precocious increase in submandibular gland-nerve growth factor (SMG-NGF) and epidermal growth factor (SMG-EGF) levels, but the mechanism(s) of T4 action has not been studied. The present report examines the role of the developing sympathetic nervous system (SNS) in the SMG-NGF and EGF responses to T4. For this purpose newborn mice were injected with T4 and/or 6-hydroxydopamine, a toxic congener of norephinephrine which causes selective destruction of sympathetic nerve terminals. The effectiveness of chemical sympathectomy was assessed by SMG-norepinephrine measurements using a sensitive radioenzymatic assay. The glandular norepinephrine contents were greatly reduced indicating that the dose and duration of 6-OHDA treatment were sufficient to cause a total sympathectomy in SMG tissue. In addition, the 6-OHDA treatment greatly reduced the wet weight and total protein content of the sympathetic superior cervical ganglia which innervate SMG tissue. SMG-NGF and EGF concentrations were measured by specific radioimmunoassays. 6-OHDA treatment alone did not affect the basal SMG-NGF and EGF concentrations. However, the maximal responses of SMGNGF and EGF to T4 administration were greatly reduced by concurrent treatment with 6-OHDA. In summary, the data demonstrate a critical role for developing sympathetic nervous system in the T4-stimulated increase in SMG-NGF and EGF concentrations.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The potential endotoxin modifying effects of subinhibitory doses of polymyxin B were evaluated in an animal model of overwhelming septicemia. Five to six day old Sprague-Dawley rats were infected intraperitoneally with 106-107cfu ofHaemophilus influenzaetype b. At 12 h after infection, at which time mortality was 18%, subinhibitory doses of polymyxin b (0.0125 mg/kg X 3 q 3 h) either alone or in combination with 500 mg/kg ampicillin significantly increased survival at 17 and 20 h (p=0.009, 0.01 andp=0.003, 0.01) compared to animals treated with 0.5 mg/kg of ampicillin alone. Prolonged survival at 36 h (p=0.009) was seen in animals receiving both ampicillin and low dose polymyxin compared to either ampicillin dose alone. Ampicillin significantly reduced the number of bacteria in blood of survivors (p<0.023 at 30 min) compared to untreated animals but increased the activity of free endotoxin at 30 min compared to controls (p=0.006).In vitroendotoxin release fromH. influenzaetype b increased 5-fold after addition of 100 µg/ml of ampicilin, whereas a six-fold reduction in endotoxin activity was measured after the addition of 7 µg/ml of polymyxin B. Subinhibitory doses of polymyxin B modulate the ethal effects of overwhelmingH. influenzaetype b infection in infant rats and might be beneficial as adjunct treatment in gram-negative septicemia.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Experiments were performed to examine how aldosterone modulates colonic NaKATPase activity during the weaning period. NaKATPase activity was determined in proximal and distal colon in control rats aged 16, 20, and 40 days, in rats aged 20 and 40 days fed low sodium diet for 4 days and in 20-day-old rats adrenalectomized on day 16. In some protocols net sodium and water transport was determined with in vivo perfusion technique. In control rats colonic NaKATPase activity increased significantly between day 16 and 20. This increase was abolished by adrenalectomy but restored by aldosterone substitution, 5 µg/100 g body weight/12 h. No significant increase in NaKATPase activity occurred between day 20 and 40. Serum levels of both aldosterone and of corticosterone were low until day 14 and increased to peak level at day 18-20. In 20- and 40-day-old rats fed a low sodium diet, NaKATPase activity increased significantly in proximal and distal colon in both age groups but the increases were significantly greater in the 20- than the 40-day-old animals. A low sodium diet increased serum aldosterone, but not serum corticosterone levels in both age groups: also the low sodium diet significantly increased net sodium and water transport in 20- but not in 40-day-old rats. Aldosterone is of physiological importance for the regulation of NaKATPase activity in the colon at the time of weaning. The immature colon may have an enhanced sensitivity to aldosterone.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Nondepolarizing muscle relaxants are administered to hypoxic neonates (including those with severe cyanotic congenital heart disease) to reduce oxygen consumption. However, it is unknown whether paralysis actually reduces oxygen consumption or whether the drugs used affect the cardiovascular system of neonates. Therefore, we studied the effects ofd-tubocurarine and pancuronium induced muscle paralysis on oxygen consumption, cardiac output, and tissue oxygen delivery in healthy normoxic and hypoxic 1- to 3-day-old lambs. We measured intravascular pressures, cardiac output and its distribution (microspheres), and blood gases and pH during: 1) spontaneous respiration with room air (control); 2) spontaneous respiration with a Pao2of 27-33 mm Hg (hypoxia); 3) mechanical ventilation with room air; 4) mechanical ventilation with room air and paralysis with rf-tubocurarine (0.3 mg/kg) or pancuronium (0.1 mg/kg); and 5) mechanical ventilation with hypoxia and paralysis. Mechanical ventilation, with or without muscle paralysis, had no effect on the oxygen delivery or oxygen consumption of normoxic animals. Hypoxia and spontaneous ventilation had no effect on oxygen consumption, but hypoxia, paralysis, and mechanical ventilation reduced it 35% (p<0.002 rf-tubocurarine) and 50% (p<0.001 pancuronium). Cardiac output was unaffected by oxygenation, mechanical ventilation, or muscle paralysis. However, blood flow to the brain and heart increased during hypoxia, which maintained normal oxygen delivery to these organs. During hypoxia and spontaneous ventilation, mean pulmonary arterial pressures increased 34% (rf-tubocurarine) and 54% (pancuronium) above control; during hypoxia, muscle paralysis, and mechanical ventilation, it increased 81%. Myocardial blood flows and right ventricular rate-pressure products increased during hypoxia and were greatest during hypoxia, paralysis, and mechanical ventilation. Serum lactate levels increased 30-50% during hypoxia and spontaneous ventilation and remained elevated for the rest of the study. These data indicate that muscle paralysis and mechanical ventilation reduce the total body oxygen consumption of hypoxic lambs, but have no effect on the oxygen consumption of normoxic lambs. They also show that muscle paralysis increases the level of hypoxic pulmonary vasoconstriction, but that paralysis does not interfere with hypoxia induced redistribution of blood flow. We conclude that similar muscle relaxant induced changes may be beneficial to most hypoxic neonates, but that the pulmonary vascular effects, if similar to those found in our lambs, may be undesirable in neonates with pumonary vascular or rightsided heart disease.

ISSN:0031-3998    

出版商:OVID    

年代:1986

数据来源: OVID