ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

To study the action of human growth hormone (hGH) on peripheral metabolism of serum thyroxine (T4), an oral loading dose of levothyroxine (1.2 mg/m2) was administered to seven children with hypopituitarism before initiation of hGH therapy. Serum concentrations of triiodothyronine (T3), T4, reverse triiodothyronine (rT3), and thyroxine-binding globulin (TBG) capacity were measured sequentially for 6 days. The study was repeated after 4 wk of treatment with hGH. Serum concentrations of T4were not affected by hGH therapy. In contrast, mean basal serum concentration of T3increased significantly after treatment with hGH. Also, changes in serum concentrations of T, and in the ratio of T3/T4 after an oral dose of levothyroxine were significantly augmented during hGH therapy. Serum concentrations of rT3changed in the opposite direction of T3during therapy. After treatment with hGH, the mean basal level of serum rT3, decreased, and increases in serum concentrations of rT3, after oral levothyroxine were significantly attenuated. No changes in mean serum concentrations of thyroid stimulating hormone (TSH) and TBG capacity were observed.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Isolated renal tubules were prepared from newborn and adult Sprague-Dawley rats. They were used to study the uptake and accumulation of the β-ammo acid, taurine, by renal epithelium. Initial rate as well as steady-state kinetics were studied. Initial rate studies revealed heterogeneity of uptake in newborn and adult tubules. Slower uptake was present in the newborn in the low-affinity system. Slowed efflux was found in neonatal tissue. Newborn tubules in contrast to adult tubules demonstrated uptake under anaerobic conditions. Adult and newborn tissues showed decreased uptake of taurine when incubated with β-alanine. Physiologic taurinuria, be it in the rat or man, may be due to less rapid initial uptake and/or slowed efflux from renal epithelium.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Peripheral blood lymphocytes from cystic fibrosis (CF) patients with advanced diseases do not proliferate following exposure toPseudomonas aeruginosa(PA) antigens inin vitro.In this study, we sought to determine if CF lymphocyte unresponsiveness to PA is due to inhibitory factors present in CF plasma. Nineteen low-responder CF (LRCF) patients increased their mean lymphocyte proliferative response ([3H]thymidine incorporation) from 703 ± 133 to 3178 ± 811 net cpm when incubated in normal plasma. These increases do not reach the level of response seen in normal individuals (8510 ± 1323 net cpm). Ten of 19 patients did not increase their responses over 2000 net cpm. Plasma from LRCF patients does not inhibit responses of normal or homologous CF lymphocytes. Responses of normal individuals in autologous plasma were 7807 ± 1164 net cpm. The same lymphocytes incubated in 16 plasmas from LRCF patients gave responses of 7146 ± 1317 net cpm. Preincubation of the PA antigen in LRCF plasma increases rather than inhibits normal lymphocyte responses. LRCF plasma absorbed with PA no longer supports normal lymphocyte responses to PA. LRCF and normal plasma mixtures increase responses of normal lymphocytes to PA over responses in autologous plasma. Extensive preincubation and washing of LRCF lymphocytes to eliminate blocking immune complexes failed to restore the ability to respond to PA. These data suggest that the unresponsiveness to PA of lymphocytes from CF patients with advanced disease is due to alterations occurring at a cellular levelin vivo.This lymphocyte dysfunction cannot be reversed by normal plasmain vitro, nor can it be induced in normal lymphocytes by the use of CF plasma.SpeculationLymphocytes from cystic fibrosis (CF) patients with advanced disease fail to proliferate in response toPseudomonas aeruginosaantigens. This abnormality cannot be reversed by the use of normal plasma or by preincubation and washing of CF lymphocytesin vitro.Heat-inactivated CF plasma does not inhibit proliferation of normal lymphocytes in response toPseudomonas.These results indicate that changes in lymphocyte reactivity occurin vivoand are unresponsive to plasma substitutionin vitro.Further investigation of quantitative and functional aspects of lymphocyte and macrophage subpopulations may elucidate the nature and significance of the unresponsiveness of CF lymphocytes toPseudomonas aeruginosa.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Hydrocortisone, prednisolone, and betamethasone were injected into a rat that was 21 days pregnant, and the fetal ductus arteriosus was studied using the rapid whole-body freezing technique. All these glucocorticoids constricted the fetal ductus arteriosus in a dose-dependent relationship. Fetal ductal constriction was maximum 1 to 4 hr after injection and was significantly more prominent in premature fetuses than in mature ones.SpeculationGlucocorticoids may be useful in constricting the patent ductus arteriosus in the premature babies in place of indomethacin, which is contraindicated in the presence of renal failure or jaundice. Administration of glucocorticoids to the mother may cause fetal ductal constriction and fetal distress.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Assessment of lung function in young children is extremely difficult unless sedation is given. If tidal exchange and intrathoracic pressure swings can be recorded, the severity of the respiratory problem can be measured by constructing pressure-volume loops and calculating the work of breathing. The system we have used to measure tidal thoracic volumes is that of a soft, rubber, inflatable jacket with pressure-volume characteristics linear from inflation pressure of 2.5 to 7 cm H2O. Oesophageal (intrathoracic) pressures are measured using water-filled nasogastric tubes (FG6). Frequency responses showed the 63% rise times for the jacket and water-filled nasogastric tube assessed together to be 10.5 msec. Recordings were traced onto a computer digitizing tablet and print-outs were obtained with the following information: respiratory rate, tidal thoracic volume, minute thoracic volume, oesophageal pressure, resistive work per min, elastic work per min, and total work per min. Comparisons were made between volumes measured using the respiratory jacket (VJ) and by pneumotachograph and integrator (VInt) in six infants.Hysteresis arising from the jacket produces some change in resistive work of breathing, but the total work of breathing is only increased by a maximum of 10.5%.Studies on healthy newborn babies showed that the jacket system tends to underrecord the resistive work of breathing, but that total work of breathing values are very similar.Reproducibility of analysis showed the following coefficients of variation from the mean: tidal thoracic volume, 1.6%; minute thoracic volume, 1.7%; resistive work, 5%; elastic work, 2%; and total work, 2.5%. The extent of breath-to-breath variation is much larger. This system makes it possible to obtain serial measurements of work of breathing without the need for sedation in infants who may be acutely ill and in respiratory failure.SpeculationTechniques are not available currently which allow us to study quantitatively the disturbances in lung mechanics which occur in respiratory failure in infancy. If we are to learn more about the natural history and response to a variety of therapeutic regimens, methods must be developed which allow us to study these children in greater detail without the need for sedation.One possible approach is to measure the total work of breathing noninvasively using the respiratory jacket to measure thoracic volume change, and measuring intrathoracic pressure changes by filling the nasogastric feeding tube with water, connecting it to a pressure-transducer, and withdrawing the tube so that its tip lies in the lower oesophagus.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

High altitude-induced hypoxemia in 26 young adults was used to compare hypoxia parameters such as blood lactate, hypoxia-induced electrocardiogram signs, and the recently proposed plasma hypoxanthine concentration. At a Pao2of 30 mm Hg, no elevation in hypoxanthine and small increase in lactate was observed. Minimal leg exercise was added to further increase hypoxia during hypoxemia. A significant increase in lactate and considerable ST-T depression in electrocardiogram indicated hypoxia, but no change in plasma hypoxanthine was found. Work-dependent hyperventilation as a main cause of lactate elevation was excluded. Blockade of hypoxanthine breakdown by allopurinolin vivoincreased plasma hypoxanthine levels, but hypoxemia with or without leg exercise failed to consistently increase this level further. Elevations of blood lactate above the normal range were found at a Pao2of 30 mm Hg and below.SpeculationThe increased plasma hypoxanthine concentration in newborns after delivery may result from other factors, additional to hypoxia, because in mild hypoxemic hypoxia in healthy adults hypoxanthine was not elevated, although blood lactate was already increased. Cellular hypoxia is indicated by beginning of lactate elevation at a threshold level of Pao2of 30 mm Hg.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Red cell glycolytic intermediates and adenosine triphosphate were evaluated in term infants from birth to one year of age and compared to values obtained from normal adults and subjects with a population of a similar mean cell age. The concentration of glycolytic intermediates, with the exception of phosphoenolpyruvate were elevated at birth when compared to normal subjects, consistent with a young mean red cell population. The mean levels of red cell glucoses-phosphate, fnictose-6-phosphate, and “total triose phosphate” were elevated on days 1 and 4 of life when compared to both red cells from normal adults and subjects with a similar young mean red cell age. Glucose-6-phosphate steadily increased in concentration, peaked at 3 to 4 wk of age, and then progressively decreased in value. Total triose phosphate declined to a mildly elevated concentration by 3 to 4 wk of age. The mean concentrations of 2,3-diphosphoglycerate and adenosine triphosphate were normal on day 1, increased on day 4, and then declined by 3 to 4 wk to normal values, until 5 to 6 months when both increased. The mean phosphoenolpyruvate concentration was decreased on day 1 of age when compared to red cells of a similar mean age, but this decrease was not significant (P> 0.05).The mean concentrations of 3-phosphoglycerate and 2-phosphoglycerate were normal for mean red cell age on day 1 of life. The concentration of 2-phosphoglycerate increased at 3 to 4 wk of age and remained elevated for cell age at 11 to 12 months but this increase was not statistically significant (P> 0.05). 3-Phosphoglycerate levels did not change significantly throughout the first year of life. At one year of age, all red cell glycolytic intermediates and adenosine triphosphate were elevated when compared to red cells from normal adults, but were comparable to those observed in subjects with a red cell population of a similar mean cell age, consistent with the persistence of a young red cell population throughout the first year of life.SpeculationThe pattern of glycolytic intermediates in the first year of life is suggestive of a relative “block” in glycolysis at the phosphofructokinase step. This block appears to result from factors other than decreased enzyme activity alone and may be secondary to an enzyme with altered kinetic properties and/or the influence of extracellular factors on enzyme activity at thein vivolevel.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

The role of mononuclear cells in generating procoagulant activity was examined by incubating Ficoll-Hypaque-separated mononuclear leukocytes with or without mitogens (phytohemagglutinin, pokeweed mitogen, and concanavalin A). The procoagulant activity was assayed by a modification of a one-stage plasma recalcification time. Significant procoagulant activity developed after 24 hr incubation and was dose dependent; mitogens alone had no effect on the clotting tune. The increase in activity was paralleled by the increase in tritiated thymidine incorporation into replicating DNA. However, mitomycin C had little inhibitory effect on the development of procoagulant activity, whereas thymidine incorporation was inhibited. The major procoagulant activity was associated with intact cells and not the conditioned supernatant. The removal of adherent mononuclear cells (mostly monocytes) by polystyrene bead columns abolished the procoagulant activity, whereas purification of mononuclear leukocyte populations for monocytes markedly increased the activity as compared to purified lymphocytes. The procoagulant activity was shown to act by the extrinsic limb of the coagulation sequence because substitution factor VII-deficient plasma for normal plasma resulted in marked depression of procoagulant activity, whereas factor VIII-deficient plasma resulted in a clotting tune only minimally longer than normal plasma. Thus, although procoagulant activity in cultures of mononuclear cells is stimulated by the mitogen reagent, these studies suggest that the activity may not be the result of the mitogenic effect on lymphocytesper se.Whether it is a direct effect of the mitogen on the adherent cell or is an effect of a contaminant of the mitogen reagent, such as endotoxin, remains to be determined.SpeculationFibrin formation is an important component of inflammatory responses. This study shows that mononuclear leukocytes can be activated to stimulate the formation of fibrin. This suggests that mononuclear leukocytes may play a key role in the deposition of fibrin in inflammatory responses.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Previous studies from our laboratory have demonstrated penetration of Evan's blue dye into the brain in profound fetal asphyxia, suggesting that vasogenic brain edema (BE) might be an immediate contributing factor hi asphyxiai brain injury. We modified the125I-labeled albumin method of Pappius and McCann to quantitate vasogenic BE after acute fetal asphyxia. With51Cr-labeled red cells to measure intravascular volume, and125I-labeled albumin to measure total tissue plasma, the equivalent extra vascular plasma volume,i.e., vasogenic BE, was calculated. Twenty chronically prepared animals were studied, six nonasphyxiated controls and 14 asphyxiated (of which six term animals were normotensive and five term and three premature animals were hypertensive during asphyxia). No difference hi extra vascular plasma volume was found between asphyxiated and control animals hi any of four brain regions. We conclude that, although blood brain barrier function might be impaired, vasogenic BE is not quantitatively significant immediately after severe fetal asphyxia.SpeculationAn episode of acute, profound asphyxia hi the fetal lamb is not accompanied by the formation of measurable amounts of vasogenic brain edema. Therefore, brain swelling is probably not an important factor in the genesis of acute hypoxic neurologic injury.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID