摘要:

ABSTRACT.We evaluated carbohydrate tolerance in nine thin cystic fibrosis (CF) patients and in six controls, measuring responsiveness to the following insulinotropic secretagogues: oral glucose, IV glucose, and IV tolbutamide. Glucose responses segregated patients into two groups: Group I with normal carbohydrate tolerance associated with normal to slightly increased insulin responses, and Group II with impaired carbohydrate tolerance associated with insulinopenia. This latter group included one patient with frank diabetes. The CF patients demonstrated a significant positive correlation between insulin secretion, in response to each secretagogue, and pancreatic exocrine function as measured by serum pancreatic amylase isoenzyme concentration. Pancreatic a-cell function, as reflected by basal plasma glucagon concentrations, also correlated well with exocrine function in the CF patients, excluding the diabetic individual. The enteroinsular axis of the CF group was intact as reflected by normal plasma gastric inhibitory polypeptide concentrations in Group I and by elevated levels, basally and in response to oral glucose, in the insulinopenic Group II patients. Furthermore, those patients with impaired tolerance demonstrated a greater magnitude of insulinopenia compared to controls following IV glucose and possibly IV tolbutamide, than following oral glucose.Thus, these data suggest that loss of carbohydrate tolerance in patients with CF, like that seen with classical chronic pancreatitis, 1) parallels the loss of exocrine function, 2) is associated with appropriate enteroinsular signaling, and 3) can be detected earlier or more easily following testing with direct IV secretagogues than following oral glucose stimulation.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.To examine the possible mechanisms of ventricular dysrhythmias in the presence of right ventricular hypertension and following ventriculotomy, we instrumented 6-month-old puppies. There were four groups: 1) six animals served as controls (instrumentation only); 2) six animals underwent ventriculotomy only; 3) six animals underwent pulmonary artery banding with a pneumatic vessel occluder to produce right ventricular hypertension; 4) six animals had both ventriculotomy and right ventricular hypertension. Each week for 8 wk, 24-h electrocardiograms and electrophysiologic studies were performed with the animals awake and unsedated. We attempted to induce ventricular dysrhythmias with premature extrastimuli, rapid pacing, isoproterenol, and vagal stimulation. The following “chronic” data were obtained in week 8 (pvalue for overall analysis of variance; values are mean ± SD): heart rate – 126 ± 16 beats/min (no significant difference between groups; all animals); right ventricular systolic pressure: control 26 ± 6 mm Hg, ventriculotomy 30 ± 3, right ventricular hypertension 65 ± 5, ventriculotomy and right ventricular hypertension 75 ± 18 (p< 0.001); right ventricular end diastolic: control 4 ± 1 mm Hg, ventriculotomy 4 ± 3, right ventricular hypertension 11 ± 5, ventriculotomy and right ventricular hypertension 16 ± 7 (p< 0.001); QRS duration: control 22 ± 5 ms, ventriculotomy 33 ± 7, right ventricular hypertension 44 ± 6, ventriculotomy and right ventricular hypertension 49 ± 4 (p< 0.01); right ventricular apex-base interval with ventricular pacing: control 20 ± 3 ms, ventriculotomy 34 ± 9, right ventricular hypertension 30 ± 5, ventriculotomy and right ventricular hypertension 31 ± 6 (p< 0.01). On 24-h electrocardiogram, there were no chronic spontaneous ventricular dysrhythmias in any control or ventriculotomy animal, but were present in 5 of 6 right ventricular hypertension animals and 6 of 6 ventriculotomy and right ventricular hypertension animals. At electrophysiology study, no ventricular dysrhythmias were induced in the control or ventriculotomy animals but in the right ventricular hypertension group, 5 of 6 had accelerated ventricular escape and 2 of 6 had induced ventricular dysrhythmias; in the ventriculotomy and right ventricular hypertension group, 5 of 6 had accelerated ventricular escape and the same 5 of 6 had induced ventricular dysrhythmias including two with sustained ventricular tachycardia. In four animals, the coupling interval to the dysrhythmia was dependent upon the preceding cycle, a feature of triggered activity. In conclusion, in the dog with an otherwise normal right ventricle, ventriculotomy has no lasting dysrhythmogenic effect. Chronic right ventricle hypertrophy and dilation are associated with prolonged intraventricular conduction, spontaneous and induced dysrhythmias. Ventriculotomy may be additive in prolongation of conduction and production of dysrhythmias. The mechanism for the dysrhythmias may involve triggered activity.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.Cerebral hyperperfusion associated with hypertension, may play an important role in the pathogenesis of intraventricular hemorrhage in preterm infants. To examine the effect of hypertension on changes in total and regional brain blood flow (BBF), we increased the mean arterial blood pressure (MABP) in nine awake newborn piglets by an infusion of 0.7 mg/kg of metaraminol bitar-trate (Aramine) (group I) and studied cerebral circulatory changes. In order to prevent the Aramine-associated bradycardia, we pretreated nine other piglets with atropine, which produced a higher level of hypertension (group II). MABP and BBF were measured and cerebral vascular resistance (CVR) was calculated during baseline, the Aramine infusion, and twice at decreasing MABP following the discontinuation of the Aramine infusion. In group I, the significant increase in MABP from 68 ± 3 to 100 ± 3 mm Hg (mean ± SEM) during the Aramine infusion resulted in a significant increase in BBF (98 ± 9 to 118 ± 11 ml-min−1100 g−1)- MABP decreased significantly (although remained significantly above baseline levels), when Aramine was discontinued; however, total BBF remained elevated. CVR increased during the Aramine infusion, but decreased significan(versusthe Aramine-infused state) in the post-Aramine period. Regional BBF increased significantly to the cerebrum and cerebellar cortex, but remained unchanged to the other regions including the brain stem. In group II, the Aramine infusion resulted in a significantly greater increase in MABP, a sustained increase in vascular resistance, and no increase in total BBF. Thus, atropine prevents increased BBF during hypertension in the newborn piglet.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.Cord blood phagocytic cells were characterized with respect to cytochemical activities, FCγ and C3b receptors, and capacity to phagocytose and kill various species of bacteria.The percentages of peroxidase-positive granulocytes and monocytes from neonates and adults were comparable; the percentage of esterase-positive cord-blood monocytes was about two-thirds of that of adults' blood monocytes. The numbers of cord blood and adults' monocytes with FCγ and C3b receptors were similar.Phagocytic and intracellular killing capacities of cord blood granulocytes and monocytes were investigated forStaphylococcus aureus, Escherichia coli, Streptococcus pyogenes,and group BStreptococcustype III. The rates of phagocytosis and intracellular killing by granulocytes from newborns proved to be comparable to the corresponding values for granulocytes from adults.Cord blood monocytes phagocytosedE. coli, S. aureus,andS. pyogenesat a normal rate, and killed ingestedE. coliandS. pyogenesintracellular at the same rate as adults' monocytes did. However,S. aureuswas killed at a much lower rate by cord blood monocytes than by monocytes from adults. Phagocytic activity for group BStreptococcuswas impaired and killing of these bacteria by cord blood monocytes was virtually nil. The latter finding might partially explain the frequent streptococcal infections in newborns.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.The acute effects of normoxemic hypocarbia and hypercarbia were examined in six newborn piglets. Brain blood flow was maintained during hypocarbia until extremely low Paco2(<15 mm Hg) levels were achieved at which time total brain and cerebral blood flow decreased significantly from baseline values. Blood flow to the thalamus, cerebellum and brain stem was unchanged from baseline conditions during hypocarbia. This suggests that the newborn brain is relatively insensitive to moderate degrees of hypocarbia. Extreme hypocarbia (Paco2<15 mm Hg) was associated with a significant increase in heart rate, accompanied by a significant decrease in mean arterial blood pressure; however, cardiac output was not significantly different from baseline determinations. Hypercarbia with normoxemia was associated with significant increases in total brain blood flow, with greater blood flow to the brain stem, cerebellum, and thalamus than to the cerebrum. The percentage of cardiac output received by the brain was also significantly increased, although total cardiac output was unchanged. This demonstrates that the newborn cerebral vasculature is sensitive to hypercarbia and that regional differences in sensitivity may account for the greater increments in blood flow to the caudal portions of the brain than that to the cerebrum.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.Muscarinic cholinergic receptors were identified and partially characterized in crude membrane fractions of rat lung and trachea from day 17 of gestation to adulthood using (-)-[3H]quinuclidinyl benzilate (QNB). (–)-[3H]QNB binding to rat lung membrane was characteristic of muscarinic cholinergic receptor sites. Binding capacity of muscarinic receptors sites was relatively low in rat lung compared to that in other tissues. The number of (–)-[3H]QNB-binding sites (binding capacity) decreased progressively and significantly from 79 ± 8 fmol mg−1protein on days 17–18 of gestation to 21 ± 3 fmol mg−1mean ± SEM on days 21–22 of gestation, p < 0.01. Binding capacity did not vary thereafter from birth to adulthood. Affinity of (-)-[3H]QNB binding for lung membranes did not change with age (KDapproximately 70 pM). (–)-[3H] QNB-binding sites were significantly higher in membrane preparations of trachea or tracheal-bronchial tissue than in lung parenchyma from both the adult and newborn rats. (-)-[3H]QNB binding was undetectable in crude membrane preparations of cultured purified type II epithelial cells isolated from the adult rat lung.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.The effects of pretreatment with methylprednisolone on the reaction to a toxin isolated from group β-hemolytic streptococci, type III, were studied in seven sheep instrumented for chronic measurements of pulmonary lymph flow and pulmonary artery and left atrial pressure. Each sheep was infused with toxin alone on one day and with methylprednisolone plus toxin on a different day in random order. The toxin alone caused a two-phase reaction. After the infusion of toxin, alone, in the initial phase, pulmonary artery pressure increased from 16 ± 1 to 45 ± 5 mm Hg and the rectal temperature rose from 39.5 ± 0.14 to 40.8 ± 0.18° C. During the second phase, the peripheral blood granulocyte count decreased to 10% of baseline values and the lung lymph protein clearance increased from 5.1 ± 1.1 to 11.2 ± 1.8 ml/h, suggesting increased pulmonary vascular permeability. Methylprednisolone pretreatment did not alter the initial phase of pulmonary hypertension or the febrile response but completely abolished the granulocytopenia and the increased pulmonary vascular permeability. These effects are unlikely to be related to inhibition of prostaglandin synthesis. Prevention of the lung vascular injury by methylprednisolone may be related to inhibition of granulocyte accumulation in the lung.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.We report a case of familial lactic acidosis, lethal in the newborn period. Studies in intact fibroblasts identified a defect in the oxidative pathway of pyruvate metabolism. Although assay of pyruvate dehydrogenase on cell sonicates was not appreciably reduced, flux through the enzyme and other mitochondrial multienzyme dehydrogenases was severely impaired in intact cells. Deficient lactate conversion to carbon dioxide could be repaired by the addition to the incubation medium of electron acceptors such as methylene blue (25 μg/ml) or dichlorophenolindo-phenol (25 μg/ml).

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Generation of oxygen metabolites is an important component of the neutrophil's armamentarium against microbes. Production of superoxide anion (O−2) and generation of hydroxyl radical (OH) were measured in neutrophils from cord blood of 12 vaginally delivered, term newborn infants and 12 adults after stimulation with phorbol myristate acetate (PMA) and opsonized zymosan. With either stimulus, generation of OH was relatively less than production of O−2for all infants studied. This discrepancy might be related to abnormal release or diminished cell content of a cofactor necessary for production of OH from O−2Since both lactoferrin (LF) found in specific granules and myeloperoxidase (MPO) found in azurophilic granules have been shown to enhance OH generation, we compared degranulation of both granule types in response to PMA and opsonized zymosan and total neutrophil content of MPO, LF, and lysozyme in cord blood and adult neutrophils. Degranulation, even after pretreatment with cytochalasin B, was the same for newborn and adult neutrophils. Content of MPO was identical (adult, 204 ± 24Aunits, mean ± SEM,n= 9; newborn, 201 ± 21,n= 9) but lysozyme was mildly diminished (adults, 111 ± 10Aunits; newborn, 89 ± 6,n= 9,p< 0.05), and lactoferrin was moderately decreased (adult, 89.0±7.3 μg/mg cell protein,n= 11; newborn, 43.2±7.0,n=11 < 0.005). Generation of Oh in response to PMA and LF content were measured in seven cord blood-adult control pairs. Both LF and OH generation were diminished in newborn cells and there was a direct relationship between OH generation and LF content. Electron microsopic studies of newborn neutrophils demonstrated evidence of degranulation and loss of specific granules. these dificits may be related to defective bactericidal activity exhibite by neutrophils from neonates. Activation of neutrophils during partuition may be the cause of the decrease in specific granules and the diminished LF content.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.Lung distensibility and airway mechanics were evaluated in 24 asthmatic children and adolescents, ages between 7 and 21 years, by quasi-static pressure-volume curves and by the static recoil-lung conductance relationship. The measurements were obtained by the stepwise inflation technique and the pressure-volume curves were analyzed by a new sigmoid exponential curve-fitting model of the form: VL = Vm + [VM/(1 + be -K.PstL)], where VL is lung volume, PstL is static recoil pressure, Vm and Vm are the upper and lower asymptotes, and K and b are shape constants. The shape constant K serves as index for lung distensibility, whereas the slope of Θ of the static recoil-lung conductance plot represents the flow-resistive behavior of the airways. The combined evaluation of these two parameters (K and Θ) shows that some asthmatic children have a very high lung distensibility and normal airway function, whereas others have nearly normal lung elasticity but grossly reduced airway distensibility. Sigmoid exponential analysis of static pressure-volume curves and an evaluation of the static recoil-lung conductance relationship in asthmatic children enable a distinction of these two types of functional derangements. Increased pulmonary distensibility consistent with an increase of alveolar air space seems to indicate an involvement of tissue elements. In contrast, decreased airway distensibility indicates a defect in the conducting airways. Sympathomimetics not only have a positive effect on airway mechanics, but seem to increase lung distensibility both in patients with hyperinflation and to an even greater degree in patients whose lungs are already too compliant.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID