摘要:

We and others previously reported DNA polymerase activity in culture supernatants of peripheral blood mononuclear cells from patients with acute Kawasaki syndrome (KS). In the present study, we further characterized the previously detected polymerase activity and attempted to confirm its presence in cultured peripheral blood mononuclear cells from additional patients with KS. Characterization experiments indicated that the polymerase activity was typical of a DNA-dependent DNA polymerase rather than viral reverse transcriptase. Peripheral blood mononuclear cell cultures from 17 additional KS patients were negative for reverse transcriptase activity in three laboratories. Our findings do not provide support for a retroviral etiology of KS. Further studies should continue to focus on infectious agents in efforts to elucidate the etiology of KS.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Levels of salivary antibodies directed againstHaemophilia influenzaeb (Hib) capsule, measured by ELISA and standardized to the total salivary IgA, were compared among 57 patients with Hib infections, 117 household and 49 day care contacts of patients, and 53 control individuals with no known contact with Hib. Nineteen of the household or day care contacts were throat or nasopharyngeal culture positive for Hib. Eighty % of evaluable patients had polyribosylribitol phosphate (PRP)-specific IgA in their saliva, compared with 36% of contacts who were throat or nasopharyngeal culture positive for Hib, 53% of contacts who were throat or nasopharyngeal culture negative for Hib, and 30% of control children. In patients, no correlation between age and level of salivary anti-PRP antibody was seen, but patients less than 3 y old were more likely to have these antibodies than were older patients. Salivary PRP-specific IgA antibodies, associated with either Hib colonization or PRP vaccination, tended to decline over time. Thus, PRP-specific IgA antibodies can be identified in the saliva of children over a wide age range, including those colonized with Hib or vaccinated with PRP, but these antibodies appear to decline after antigenic stimulation ceases.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Pigs demonstrate an increased sensitivity and susceptibility toEscherichia coliheat-stable enterotoxin (STa) in the 1st wk of life and immediately after weaning. To determine the possible mechanisms for this increased susceptibility, we compared STabinding, guanylate cyclase activation, and photoaffinity cross-linking to porcine jejunal brush border membranes prepared from immature (≤ wk of age)versusadult pigs as well as 3-wk-old weanedversusunweaned pigs. The STabinding capacity of immature pigs was nearly twice that of adult pigs (11.73 ± 1.52versus6.00 ± 0.96 x 10-11mol/L,p< 0.001), and the STabinding capacity of weaned pigs was nearly three times greater than that of unweaned pigs (17.48 ± 2.10versus4.86 ± 1.02 x 10-11mol/L,p< 0.001). Scatchard analysis suggested a single class of STareceptor, with an association of binding constant of ∼109L/mol at all ages. Maximum guanylate cyclase response (expressed as pmol cyclic GMP generated/mg brush border membrane protein/min) was greater in immatureversusadult pigs (1312 ± 831versus320 ± 92,p< 0.02). Weaned pigs had a greater maximum guanylate cyclase activation than unweaned pigs (1126 ± 692versus624 ± 298); however, this difference was not statistically significant. Autoradiograms demonstrated specific cross-linking of125I-STato a number of distinct radiolabeled bands (62, 66, 84, 92, 160, and 165 kD). There was a difference in the size and trypsin sensitivity of these radiolabeled bands as a function of age and weaning. Treatment with trypsin decreased the intensity of the 160 to 165-kD bands while increasing the intensity of the 62− to 66− and 84− to 92-kD bands. These differences in STabinding, guanylate cyclase activation, and STareceptor size may increase the susceptibility of pigs during the 1st wk of life and at weaning to STa-mediated diarrheal disease.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Binding of secretory IgA (sIgA) to human milk macrophages was identified by rosette formation with sIgA-sensitized indicator cells and competitive inhibition binding studies with [125I]-sIgA. Macrophages formed rosettes with sIgA-sensitized sheep red blood cells that were inhibited by sIgA (87%) but not IgG. Both IgA1and IgA2inhibited sIgA-sensitized sheep red blood cell rosette formation. Rosette formation was completely inhibited by galactose, partially inhibited by asialofetuin, and unaffected by mannose. [125I]-labeled sIgA binding to macrophages reached a plateau after 60 min, was dependent on the number of macrophages in culture, and was specifically inhibited by unlabeled sIgA. Incubation of macrophage monolayers with increasing concentrations of sIgA-anti-IgA immune complexes resulted in a progressive increase in the oxidative burst and increased secretion of prostaglandins. These studies indicate that human milk macrophages have a receptor for sIgA and that activation of these macrophages may occur via these receptors.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

In a study of absorption of iron from meals by preadolescent children (Tanner stage 1), we had noted that erythrocyte incorporation of the extrinsic iron label was somewhat greater by girls than by boys. Although the difference was not significant, the observation seemed to warrant further study. Study A: A precisely determined quantity of ferrous sulfate enriched with the stable isotope58Fe was given without food to 15 boys and 15 girls (Tanner stage 1) after an overnight fast and was immediately followed by a dose of 70 mg of ascorbic acid.58Fe enrichment of the erythrocytes was determined by inductively coupled plasma mass spectrometry at baseline and 14 and 42 d after administration of the58Fe dose. Geometric mean erythrocyte incorporation of the58Fe label was 35.2% of intake by boys and 45.0% of intake by girls. The difference was significant (analysis of covariance with serum ferritin as covariate,p= 0.035). Study B: Fifteen boys and 15 girls (Tanner stage 1) were fed a breakfast labeled with58Fe. Geometric mean erythrocyte incorporation of the58Fe label was 14.8% of intake by boys and 24.7% of intake by girls. The difference was significant (analysis of covariance with serum ferritin as covariate,p= 0.004). Because serum ferritin concentrations were similar in boys and girls, the gender-related difference in iron absorption (as reflected by erythrocyte incorporation of the label) does not appear to be explained by a difference in body stores of iron. We hypothesize that hormonal differences between boys and girls in Tanner stage 1 favor iron absorption by girls.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Our study was designed to assess the role of selenium (Se) in development of neonatal lungs under conditions of normoxia and hyperoxia. Thirty-six female Sprague Dawley rats were bred and fed a Se-deficient (0.03 ppm Se) or a Se-adequate (0.5 ppm Se) diet during pregnancy and lactation. At d 2 postpartum, 24 litters were randomly assigned to either high oxygen (>95%) or air and were cross-fostered for 4 d. Lung weight was significantly enhanced in Se-adequate pups and was not related to high oxygen or air exposure of either the pups or dams. Two types of histologic lesions were observed in the lungs of the pups: septal attenuation and interstitial inflammation. When reared in oxygen, all (17 of 17) Se-deficient pups had lesions. In contrast, only 60% (9 of 15) of Se-adequate pups were affected (plt; 0.01). Lung lesions also were more severe in Se-deficient pups. Se-deficient pups also displayed a significant degree of septal attenuation when reared in air. Se-dependent glutathione peroxidase activity in the pup lung was significantly elevated in response to hyperoxia and was unrelated to Se nutriture. No differences in activities of lung superoxide dismutase, catalase, and glutathione s-transferase were noted between Se-deficient and Se-adequate pups reared in air or high oxygen environments. These data indicate that Se has an important role in the development of neonatal lungs, a role that is even more pronounced during conditions of hyperoxia. The protective role of Se in developing lung tissue cannot be completely explained by enhanced glutathione peroxidase activity.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Xanthine derivatives relax adult airway smooth muscle (ASM). To determine whether caffeine and theophylline relax preterm ASM contracted by acetylcholine, 27 tracheal rings obtained from seven preterm lambs (120–135 d gestation) were studied. ASM was contracted using 10-5M acetylcholine (control) after the muscle was stretched to the length at which maximum active tension was developed isometrically. Concentration-effect curves for each xanthine were obtained by cumulative addition of the drug. Theophylline produced a significant decrease (p< 0.001) in active tension at each dose, whereas caffeine significantly increased (p< 0.001) active tension at 10-4and 10-3M concentrations. Addition of caffeine and theophylline to previously uncontracted ASM did not alter tension. Thus, it appears that, in contrast to their effect on adult ASM, the xanthine derivatives caffeine and theophylline have differential effects on prestimulated ASM in preterm lambs. These findings raise important questions about various aspects of the current therapeutic use of caffeine and theophylline.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Previously, we reported that the major site of pulmonary vascular resistance in fetal lambs occurred in the middle region defined by vascular occlusion, and that this region exhibited the greatest decrease upon ventilation with O2. To assess the relative individual contributions of ventilation and oxygenation to this decrease, we determined the distribution of pressures across the pulmonary circulation in isolated perfused lungs from 20 fetal lambs (131–137 d gestation) by inflow and outflow vascular occlusions. A membrane oxygenator was included in the extracorporeal circuit to control the Po1at 4 kPa (30 torr) in the unventilated fetal lungs. Half of the fetal lungs were ventilated first without changing the initial gas tensions, and the others were oxygenated first by changing the initial gas tensions to a hyperoxic mixture [Po2= 26.6 kPa (200 torr)] without ventilation. Finally, both groups of lungs were ventilated and oxygenated. In addition, indomethacin was added to the perfusate (0.112 mM, or 40 μg/mL) in half of the preparations in each group to determine the effect of prostaglandins on the distribution of pressures during these conditions. The decrease in the total pulmonary vascular resistance with ventilation and/or oxygenation was primarily due to changes in the middle pressure gradient (ΔPm). In fetal lungs without indomethacin, ventilation without oxygenation reduced ΔPm from 6.1 ± 0.8 to 2.5 ±1.0 kPa, or 74% of the total ventilation- and oxygenation-induced decrease in ΔPm (final value = 1.2 ± 0.6 kPa). In contrast, oxygenation without ventilation produced a decrease in ΔPm from 5.5 ± 0.7 to 3.8 ± 0.5 kPa, only 40% of the total decrease in ΔPm (1.2 ± 0.4 kPa). Furthermore, in fetal lungs with indomethacin, only oxygenation first caused a reduction in the resistance of the middle region, suggesting that dilator prostaglandins are not involved in the response to increased oxygen. We conclude that recruitment and/or distension of the small pulmonary vessels functionally located in the middle region by the mechanical effect of ventilation is dependent on dilator cyclooxygenase products, and that this mechanical effect is a major factor involved in the decrease in pulmonary vascular resistance occurring at birth.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Urinary levels of leukotriene (LT) E4, a stable end-product of LTC4and LTD4, were measured before and after exercise in 10 children with severe asthma and seven children with moderate asthma using HPLC and RIA to clarify the relationship of LT to the severity of asthma and to the degree of bronchospasm in exercise-induced asthma. The urinary LTE4level significantly increased after exercise in the severe asthma group, but not in the moderate asthma group (14.3 ± 14.5 to 24.3 ± 20.6versus19.6 ± 12.3 to 17.6 ± 10.8 ng/mmol creatinine,p< 0.05). The urinary LTE4level increased in 10 patients (eight with severe asthma), and it decreased in seven patients (five with moderate asthma). A significant difference in the degree of bronchospasm after exercise (as shown by the maximal % fall in the peak expiratory flow rate), was seen when patients with increased urinary LTE4excretion were compared with those with decreased excretion (60.4 ± 17.3versus24.1 ± 14.3%,p< 0.01). Our findings suggest that exercise-induced asthma, or at least a subtype of exercise-induced asthma, may partly develop through the release of LTC4.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Synthetic pulmonary surfactants consisting of mixtures of phospholipids with synthetic peptides based on the amino acid sequence of human surfactant apoprotein SP-B were prepared. These surfactants were analyzed for their ability to lower surface tension on a pulsating bubble surfactometer and for their capacity to improve lung compliance and increase alveolar expansion in a fetal rabbit model of surfactant deficiency. The data demonstrate that several peptides, ranging from 17 to 45 residues in length, matching the carboxy-terminal sequence of the SP-B protein, when appropriately recombined with the phospholipids dipalmitoylphosphatidycholine and phosphatidylglycerol (3:1), are capable of producing a synthetic surfactant with biophysical and biologic activity approaching that of human surfactant derived from amniotic fluid.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID