ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The cytotoxicity of natural killer (NK) cells against X562 cells and their responsiveness to interferonα and interleukin 2 (IL-2) were studied throughout child-hood using51Cr-release and single-cell assays. Although NK activity was extremely low in the neonatal period, it almost reached the adult level during 1 to 5 mo of age and remained at that level thereafter. At the single-cell level, the binding, lytic, and recycling abilities were also depressed in the neonatal period, but these abilities improved conspicuously after this period; in particular, the lysis and recycling were at higher levels during 6 mo to 4 y of age. The absolute numbers of circulating cytotoxic NK cells were high during infancy to early childhood: they were 54 \pm 24 (mean \pm SD/mm3) in neonates, 115 \pm 48 in 1− to 5-mo-old infants, 121 \pm 42 in 6− to 12-mo-old infants, 93 \pm 26 in 1− to 4-y-old children, and 42 \pm 16 in adults. Inter feron-α and IL-2 could enhance NK activity throughout childhood. The IL-2 enhancement was prominent especially in the neonatal period; IL-2 yielded a 2.5-fold in crease in the number of cytotoxic cells and improved the recycling to the adult level. At older ages, interferon-α and IL-2 yielded 1.4-and 1.9-fold increases in the number of eytotoxic cells, respecively, but did not enhance the recycling. The iacreased number of NK cells with adequate cytotoxic abilities during infancy to early childhood indicates the predominance of NK immunity during these periods. IL-2 is a cytokine that induces high levels of NK cytotoxicity even in neonates. (Pediatr Res28: 316–322, 1990)

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

In vitro, IL-6 can induce hematopoietic progenitors to progress from Gointo cycle, but a role for IL-6 in regulating cycling status of progenitorsin vivohas not been established. In our studies, groups of five to six adult and newborn rats received i.v. injections of either IL-6 (1 ng/g body wt) or the vehicle (control), after which cycling of hematopoietic progenitors was evaluated by tritiated thymidine suicide. Progenitors from adult rats injected with the control had thymidine suicide rates of 7 \pm 1% (mean \pm SEM), compared with 23 \pm 7% in the IL-6 recipients (p< 0.02), Progenitors from newborn rats injected with the control had thymidine suicide rates of 19 \pm 2%, compared with 29 \pm 1% in the IL-6 recipients (p< 0.003). In addition, IL-6 administration resulted in release of cells from the nentrophil storage pool into the circulation, as evidenced by fewer polymorphonuclear cells flushed from the long bones (neonates,p< 0.001; adults,p< 0.003), a rise in blood neutrophil concentration (neonates,p< 0.001; adults,p< 0.005), and a leukocyte "left shift" (neonates,p< 0.001; adults,pPediatr Res28: 323–326,1990)

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Neutrophils (PMN) from newborn calves generate significantly less superoxide anion (O2-) than do their adult counterparts after stimulation with direct protein kinase C agonists. To better understand this observation, we compared the activity and kinetics of NADPH oxidase in membrane fractions from phorbol 12-myristate 13-acetate-stimnlated adult and newborn PMN. After phorbol 12-myristate 13-acetate stimulation, PMN were sonicated and the membranes assayed for O2- production with increasing concentrations of NADPH. O2- production was calclated 1 and 2 min after the begianing of the reaction. At all concentrations of NADPH ased, there was no difference (p> 0.05) in O2- production between adult (n = 8) and newborn (n = 9) PMN membrane preparations. Enzyme kinetics calculations revealed no differences (p> 0.05) between age groups in Km and Vmax or in the velocity of the reactions. Determination of the protein content in the membrane pellet, however, showed that adlut PMN yielded significiantly (phigher amounts of protein (2.82 \pm 0.14 mg/ml) than did newborn PMN (1.78 \pm 0.07 mg/mL). This difference could be partly attributed to cell size; flow cytometric analysis showed that newborn PMN had a significiantly (pp< 0.01) in newborn PMN. These data collectively showed that the observed difference in O2- production between newborn and adult bovine PMN stimulated with protein kinase C agonists was not due to a difference in the activity or the kinetics of the enzyme NADPH oxidase, and that PMN from newborn calves had a significantly smaller diameter, volume, and surface area than did adnlt PMN. These size differences could play a role in the O2- generating deficit of newborn bovin PMN. (Pediatr Res28:327–331,1990)

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

To establish a parameter for zinc status that is independent of the occurrence of infection, we studied the effects of low dietary zinc and endotoxin in weaning rats 21 d after65Zn intubation. We monitored aspects of zinc status (tissue zinc content,65Zn distribution, and specific65Zn activity in tissue) and65Zn metabolism (absorption, excretion, and biologic half-life), as well as weight gain, feed conversion, and dietary zinc use. The low zinc diet iuduced classical deficiency with losses of bone zinc, resulting in lower content (7.4 versus 19.6 μmol) and higher specact (17versus8 kBq/μmol). Other tissue-specific and plasma-specifie activities were also higher (overall, 20versus8 kBq/μmol; plasma, 8versuskBq/μmol). Endotoxin caused lower total-plasma zinc (0.04versus0.05/μmol) but did not affect spec act (4 kBq/μmol): combined endotoxin and low-zinc diet caused low total-plasma zinc (0.01 μmol) and high spec act, as did the low-zinc diet alone (12 kBq/μmol). We conclude that plasma-spec act (or stable isotope enrichment) can serve as an index for nutritional zinc status during recurrent infection. (Pediatr Res28: 332–335,1990)

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Guinea pig gallbladder smooth muscle contractility undergoes a period of postnatal maturation. Because tissues from adult animals contract more forcefully than tissues from newborn animals when stimulated with agonists that activate the contractile process through different mechanisms (receptor activation, membrane depolarization), we proposed that factors unrelated to the mechanism of action of the agonist may contribute to the difference in force development between the age groups. Our study tested this hypothesis by examining thein vitrocontractile response to calcium of membrane skinned muscle preparations from newborn and adult guinea pigs. Cell membranes were permeabilized using a Triton X-100 (0.5%) skinning solution. The muscle strips were rinsed in relaxing solution then contracted with calcium. The contracting solution contained either 1, 5, 10, or 20 μM calcium. Each muscle strip was stimulated with a single concentration of calcium. The resutls can be summarized as follows: I) the maximal response of the skinned preparations did not differ from that of membrane intact preparations: 2) tissues from each age group contracted in a dose-response manner with the maximal response occurring at 10 μM calcium; and 3) at each caleium concentration, tissues from adult animals devellped more active force than tissues from newborn animals. The data suggest that the postnatal maturation of gallbladder smooth muscle contractility includes factors involved in calcium activation of the excitation-contraction compling process. (Padiatr Res28: 336–338, 1990)

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Bile secretion of trace elements, analyzed by proton-induced x-ray emission, was studied in rats with a congenital defect in hepatobiliary transport of organic anions Groningen Yellow (GY) rats, in which the process of bile secretion resembles that of the neonatal period. Bile flow(-41%) and biliary glutathione secretion(-99%) were drastically imparied in Gy rats compared with controls. Plasma concentrations of all detectable trace elements (Fe, Cu, Zn, Mo, Br, and Se), as well as that of simultaneously determined Ca, were similar in GY and age-matched control Wister rats. Bile concentrations of Fe, Mo, Br, and Ca were also similar in both groups, resulting in a ∼40% reduction of their secretion rates in GY rats. The concentrations of Zn(-62%) and Mn (-64%) were significantly lower in GY rats in contrast to that of Ca, which was 50% higher. Se could not be detected in bile of either group. Recovery in bile (% dose/3 h) after i.y. injection of MnCl2, CuSO4, or SeO2(1 mg metal/kg) was lower in GY rats than in controls: Mn, 26 and 35%; Cu, 2.6 and 5%; and Se, 1.5 and 5%, respectively, injection of ZnSO4did not lead to increased Zn secretion in GY rats, and only 1.1% of the dose was recovered in controls. Thus, the hepatic handling of different endogenous and exogenously admjnistered trace metals is affected to a variable extent in the GY rat. For a number of metals (e.g.Fe, Mo), this may be related to the reduced bile flow: for others (e.g.Zn, Ma, Cu), other regulatory factors appear to be responsible. (Pediatr Res28: 339–343, 1990)

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Cardiac failure and skeletal muscle weakness are the main clinical features of glycogenosis type II, a lysosomal storage disorder caused by acid α-glucosidase deficiency. In our study, we have investigated in a rat heart perfusion-recirculation system whether acid α-glucosidase can be taken up from the vascular system into cardiomy-ocytes. When rat hearts were perfused with mannose 6-phosphate-containing acid α-glucosidase purified from bovine testis, a 3− to 4-fold increase of enzyme activity was obtained, Perfusion with human placental acid α-glucosidase not containing the mannose 6-phosphate recognition marker did not have such an effect. The presence of bovine testis acid α-glucosidase in heart tissue was demonstrated by immunoblotting. Immunocytochemistry provides evidence for uptake of the exogenous enzyme in lysosomes of the cardiomyocytes. The relevance of these findings for enzyme therapy in glycogenosis type II is discussed. (Pediatr Res28; 344–347,1990)

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Interstitial transudate and coronary venous concentrations of adenosine, inosine, and hypoxanthine were determined in isolated isovolumic immature and mature rabbit hearts during normoxia and hypoxia. During normoxia, interstitial transudate adenosine was lower in immature hearts compared with mature hearts. Interstitial transudate concentrations of adenosine, inosine, and hypoxanthine were 130 \pm nM, 699 \pm 88 nM, and 392 \pm 80 nM, respectively, in immature rabbit hearts and 228 \pm 35 nM, 1154 \pm 126 nM, and 287 \pm 30 nM, respectively, in mature rabbit hearts. Interstitial transudate adenosine was significantly lower in the immature hearts. Coronary venous purine concentrations were 6− and 8-fold lower than their respective intersutial transudate concentrations during normoxia in both age groups. Hypoxia significantly increased interstitial transudate purines in both age groups. Interstitial transodate adenosine, inosine, and hypoxan-thine increased to 1180 \pm 231 nM, 4049 \pm 500 nM, and 1099 \pm 98 nM, respectively, in immature hearts and to 1225 \pm 300 nM, 5220 \pm 1217 nM, and 876 \pm 147 nM, respectively, in mature hearts. The age-related difference in transudave adenosine levels present during normoxia was not detected during hypoxia. Venous purine levels increased during hypoxia and the gradient from interstitial transwdate fi to venous effluent was abolished for adenosine in both groups. In immature hearts, hypoxia led to higher venous effluent adenosine leyels than in the mature hearts. Coronary resistance correlated with interstitial transndate adenosine in both groups, although immature hearts displayed lower resistances at all adenosine levels. The results indicate that1) interstitial transudate adenosine may regulate coronary resistance during hypoxia in isolated hearts from both age groups,2) age-related differences exist in the normoxic release of interstitial transudate adenosisne, and3) age-related differences appear to be present in the release of purines into the coronary venous effluent during hypoxia. (Pediatr Res28: 348–353, 1990)

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID