摘要:

Amniotic fluid samples were obtained by transabdominal amniocentesis from 20 women in preterm labor (≤34 wk gestation). Concentrations of IL-6 in culture-positive amniotic fluids (mean 8706 pg/mL, range 5100–14 446 pg/mL) were higher than those in culture-negative fluids (mean 1133 pg/mL, range ≤5–6534 pg/mL, p < 0.0001) or fluids from healthy term pregnancies (mean 196 pg/mL, range ≤5–790 pg/mL, p < 0.001). To assess possible sources of the IL-6 in amniotic fluid, we tested the ability of a variety of fetal and maternal cells to produce IL-6in vitroafter stimulation with IL-1, a cytokine known to stimulate IL-6 production. Very low concentrations of IL-6 were present in supernatants of cells not stimulated with IL-1; however, high concentrations were observed in supernatants of stimulated umbilical venous endothelial cells, decidual cells, and fetal and maternal blood mono-nuclear cells. To determine whether cells from adults produce IL-6 with kinetics similar to those of neonates, we incubated mononuclear cells obtained from blood of adults and term and preterm neonates with IL-1. After 6 h, IL-6 was detected in supernatants of adult cells and term neonatal cells, but not in supernatants of preterm cells. Concentrations at 18, 24, and 48 h were similar for adult and term cell supernatants, but were lower in supernatants of preterm cells. We also observed considerably more IL-6 mRNA accumulation in circulating mononuclear cells from adults than in those from neonates.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

ABSTRACTClones of hepatitis B virus (HBV) DNA were propagated from sera of two babies who developed neonatal fulminant hepatitis B, as well as from sera of their mothers who carried HBV with antibody to hepatitis B e antigen, and the precore-region sequences were determined. A point mutation from guanine to adenine, converting codon 28 for tryptophan (TGG) to a stop codon (TAG), was detected in 18 of 20 HBV DNA clones from mother and all 31 clones from baby in one family, and invariably in 55 clones from mother and three clones from baby in the other family. These results indicate that HBV mutants defective in the precore region in some carrier mothers with antibody to hepatitis B e antigen may transmit fulminant hepatitis B to their babies.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

TwoHaemophilus influenzaetype b (Hib) polysaccharide-protein conjugate vaccines were evaluated for immunogenicity in eliciting anti-polyribosyl ribitol phosphate (PRP) antibodies in infant rhesus monkeys. Animals received intramuscular injections of either Hib polysaccharide (PRP)-meningococcal outer membrane protein complex or Hib oliosaccharide-CRM197(HbOC) conjugate vaccines on d 0,28, and 56. Because HbOC contains the CRM197mutant diphtheria toxin fromCorynbacterium diphtheriaeas its protein carrier, the effect of simultaneous injection of diphtheria toxoid on the immunogenicity of HbOC also was evaluated by dividing monkeys vaccinated with HbOC into three groups: HbOC/saline, HbOC/diph-theria and tetanus toxoids, and HbOC/tetanus toxoid (coadministration of HbOC and other vaccine or placebo injected into the flank muscle of different legs). Infant monkeys vaccinated with the PRP-outer membrane protein complex conjugate responded with anti-PRP antibody after the first dose and showed booster responses after the second and third injections. In contrast, infant monkeys vaccinated with HbOC did not respond after three doses of HbOC/saline or HbOC/tetanus toxoid. However, two of three monkeys given concurrent injections of HbOC and diphtheria and tetanus toxoids did respond. The nonresponder monkey to three doses of HbOC and diphtheria and tetanus toxoids did respond to a subsequent injection with PRP-outer membrane protein complex. Thus, concomitant administration of diphtheria toxoid, a common vaccine for human infants, is necessary to elicit an anti-PRP antibody response to HbOC. This finding suggests that the CRM197protein, at the 12.5-μg dose of protein in the HbOC used in this study, may not be sufficiently immunogenic in naive infant rhesus monkeys to permit an antibody response to the Hib oligosaccharide component of the conjugate.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

EnterohemorrhagicEscherichia coli(EHEC) are associated with hemorrhagic colitis and hemolytic uremic syndrome. These illnesses are typically seen in young children, but are rare before 6 mo of age. The cause of this age restriction is unclear. Because bacterial adherence to intestinal mucosa is considered a critical initial event in pathogenesis, we studied the ontogeny of the adherence of EHEC (0157:H7 and other serotypes) isolated from children with diarrhea, hemorrhagic colitis, or hemolytic uremic syndrome. Adherence was quantitatively determined by incubating radiolabeled bacteria with viable rabbit intestinal cells, which were prepared by treating loops of distal ileom and proximal colon with EOTA, DTT, and citrate. Cells obtained from animals of different ages were studied simultaneously. The adherence of the various EHEC strains varied significantly. A non-0157:H7 E.colistrain 43–12 bound best (35 and 32 bacteria/cell to ileal and colonic cells, respectively) with 48–60% inhibition by D-mannose and α-methyl mannoside (p < 0.01) and 20–28% inhibition by L-fucose (p < 0.05), but no significant inhibition by other carbohydrates. Analysis of variance and polynomial regression showed that postnatal age significantly affected the adherence to ileal and colonic cells. Adherence during the 1st wk of life was 13–19% of that in the adult animal; it increased gradually, reaching the adult level at about 4 wk of age. Our study shows that postnatal age affects the adherence of EHEC to intestinal cells. These findings are compatible with postnatal development of gut receptors and may be relevant to the age-related risk of EHEC disease in children.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

ABSTRACTWe studied smooth muscle strips from rabbit distal colon to determine age-related changes in length-tension properties and agonist-mediated contraction. Strips from newborn (1-d-old) and weanling (11-wk-old) rabbits were oriented to measure isometric tension in longitudinal muscle. Active tension comprised 47 ≤ 4 and 75 ≤ 5% of the total tension in the newborn and weanling, respectively. Total and active tensions in the weanling were greater than in the newborn (p < 0.001). Although the potencies for bethanechol were similar, the maximal response was nearly 9-fold greater in weanlings (6900 ≤ 292 mN/cm2)versusnewborns (753 ≤ 112 mN/cm2) p < 0.001. Maximal stress increased with age for bethanechol, high extracellular potassium, substance P, neurokinin A, cholecystokinin octa-peptide, bombesin, and serotonin. ED50for bethanechol, substance P, neurokinin A, and bombesin did not change with age. Serotonin was 12 times more potent in newbornsversusweanlings (p < 0.05). In contrast, cholecystokinin octapeptide was five times less potent in newborns (18.6 nMversus3.4 nM, respectively, p < 0.05). Substance P-induced contractions were inhibited partially by atropine. We conclude that length-tension properties of longitudinal colonic smooth muscle differ, and responses to agonists increase with age.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

ABSTRACTInherited selective intestinal malabsorption of cobalamin (Cbl) was observed in a family of giant schnauzer dogs. Family studies and breeding experiments demonstrated simple autosomal recessive inheritance of this disease. Affected puppies exhibited chronic inappetence and failure to thrive beginning between 6 and 12 wk of age. Neutropenia with hypersegmentation, anemia with anisocytosis and poikilocytosis, and megaloblastic changes of the bone marrow were present. Serum Cbl concentrations were low, and methylmalonic atiduria and homocysteinemia were present. Parenteral, but not oral, cyanocobalamin administration rapidly eliminated all signs of Cbl deficiency except for low serum Cbl concentrations. Cbl malabsorption in affected dogs was documented by oral administration of [57Co]cyanocobalamin with or without simultaneous oral administration of intrinsic factor or normal dog gastric juice. Quantitation and function studies of intrinsic factor and transcobalamin-II from affected dogs revealed no abnormality. Other gastrointestinal functions and ileal morphology were normal, indicating a selective defect of Cbl absorption at the level of the ileal enterocyte. Immunoelectron microscopy of ileal biopsies showed that the receptor for intrinsic factor-Cbl complex was absent from the apical brush border microvillus pits of affected dogs. This canine disorder resembles inherited selective intestinal Cbl malabsorption (Imerslund-Grasbeck syndrome) in humans, and is a spontaneously occurring animal model of early onset Cbl deficiency.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

To determine the effects of dietary and biliary lipid absorption on intestinal apo B-48 and apo A-I synthesis in the newborn piglet, 2-d-old female piglets were prepared with a duodenal infusion catheter. After recovery, animals were given either low triglyceride (Vivonex; VIV group) or high triglyceride (Intralipid; FAT group) diets by continuous intraduodenal infusion for 24 h. A bile-diverted group was also studied. Segments of proximal jejunum and distal ileum were then pulse-radiolabeledin vivowith3H-leucine. Mucosal apo B-48 and apo A-I were immunoprecipitated, and apoprotein synthesis was expressed as percentage of total protein synthesis. Mucosal apoprotein content (ng apoprotein/μg total protein) was measured by competitive ELISA assays. In jejunum and ileum, apo B-48 synthesis was not different in the three groups. However, apo B content increased 2.4-fold in jejunum and 1.7-fold in ileum in the FAT group compared with the VIV group. Immunoblotting revealed the majority of jejunal apo B to be apo B-48, not apo B-100 from contaminating plasma lipoproteins, in all three experimental groups. Bile-diverted animals had decreased jejunal apo B content compared with the VIV group. Jejunal apo A-I synthesis and content were approximately 2-fold higher in FAT animals compared with the VIV group. Although ileal apo A-I synthesis was also 2-fold higher in the FAT group, apo A-I content was not different from the VIV group. Neither jejunal nor ileal apo A-I synthesis was significantly affected by bile diversion, even though jejunal apo A-I content was decreased by over two thirds compared with the VIV animals. In the newborn piglet, intestinal synthesis of apo B-48 and apo A-I is differentially regulated by luminal lipid absorption. Although fat feeding and bile diversion regulate mucosal apo B-48 content, synthesis is unchanged, indicating a posttranslational regulatory mechanism. In contrast, apo A-I synthesis generally parallels mucosal apo A-I content except in distal ileum. Changes in jejunal apo B content and apo A-I content and synthesis parallel changes in mucosal triglyceride content. However, changes in ileal apo B content and apo A-I synthesis were not accompanied by changes in ileal triglyceride content, suggesting other regulatory factors in the distal small intestine.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

We compared peroxidizability of neonatal and adult lipoproteins exposed to oxidative stress initiated by an azo-compound. Oxygen uptake showed a two-phase pattern, with slow oxygen uptake in the first phase and faster uptake in the second phase. During the first phase, tocopherol was consumed progressively, inhibiting lipid peroxidation by scavenging peroxy radicals. After the tocopherol concentration fell below a critical level, extensive propagation of chain oxidative reactions produced the rapid oxygen uptake in the second phase. In the first phase of neonatal lipoprotein oxidation, a faster oxygen uptake was observed and the length of this phase was shorter than in adults. The oxygen uptake rate in the second phase was smaller in the neonatal lipoproteins. In other words, neonatal lipoproteins were more susceptible to oxidative stress than were adult ones when tocopherol remained in lipoproteins, but after tocopherol depletion the reverse was true. These results were consistent with the finding that in neonatal lipoproteins the tocopherol/lipid ratio was significantly lower (length of the inhibitory phase was closely correlated to the lipoprotein tocopherol content). In addition, the average number of active bisallylic hydrogen atoms, which are considered to determine the relative susceptibility of polyunsaturated fatty acids to oxidation, was significantly smaller (oxygen uptake rate in the second phase was closely correlated to the active bisallylic hydrogen number) in neonatal lipoproteins, and the ratio of active bisallylic hydrogen to tocopherol content (which closely correlated to oxygen uptake rate in the first phase) was also significantly lower compared with the adult ratio. Under physiologic conditions, an intensive oxidation of lipoproteins sufficient to cause lipoprotein tocopherol to fall below critical levels is unlikely to occur. Therefore, it seems reasonable to suggest that neonatal lipoproteins are more susceptible to oxidative stress than are adult lipoprotein.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Lingual lipase in the rat is present in the neonatal period and undergoes developmental increase during postnatal life. To evaluate the role of glucocorticoid in the control of lingual lipase during development, suckling rats were adrenalectomized at d 10 and various hormone replacements were performed. Adrenalectomy abolished the developmental increase of lingual lipase. Low doses of dexamethasone (0.2 and 0.5 μg/100 g body wt) restored the lingual lipase to near normal level in adrenalectomized animals. High doses of dexamethasone (20 μg/100 g body wt), when given to similarly adrenalectomized animals, however, led to a reduction of lingual lipase levels. Inhibition by dexamethasone is through the action of the hormone inasmuch as the coadministration of RU38486, a glucocorticoid type II receptor antagonist, completely abolished the inhibitory action. Inhibition is also steroid specific, with dexamethasone and triamcinolone acetonide being more effective. The results suggest a unique bimodal regulation of lingual lipase by dexamethasone in the rat serous glands. Because of the possible importance of lingual lipase as an alternative enzyme for fat digestion in neonates, the inhibitory action of high doses of glucocorticoid on lingual lipase development may have important implications. The use of steroidal compounds in the hastening of long maturation and treatment of inflammatory disease might conceivably compromise their lingual lipase development, hence their capacities of fat digestion and malabsorption in the same period.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

IGF-I and -II are peptide growth factors that may be important contributors to the growth-promoting properties associated with milk. IGF in extracellular fluids, including serum and milk, are carried by specific high-affinity binding proteins (IGFBP). In this study, the levels of IGF-I and -II in rat serum and milk were quantified by specific RIA, and the IGFBP were characterized using Western ligand blotting and autoradiography throughout lactation. The levels of IGF-I in both milk and maternal serum decreased during lactation. Serum IGF-I decreased from 743 ≤ 187 μg/L on d 1 to 391 ≤ 106 (mean ≤ SD) on d 21 of lactation, and milk IGF-I levels fell from 30 ≤ 10 to 13 ≤ 8 μg/L. Levels of IGF-II in serum and milk were much lower than IGF-I, and were unaffected by lactation. In maternal serum, several IGFBP were identified: IGFBP-3, which migrates as four glycosylated bands with apparent M, from 38 to 42 kD and one to two nonglycosylated bands with apparent M, of 28 to 29 kD, and an IGFBP with an apparent M, of 24 kD. In milk, IGFBP-3, the 24-kD binding protein, and a third IGFBP with an apparent M, of 29 kD were identified. Treatment of milk and serum with Endoglycosidase F reduced the four glycosylated IGFBP-3 bands (38–42 kD) to two bands with apparent M, of 35 and 32 kD. In rat milk, but not adult rat serum, the IGFBP with an apparent M, of 29 kD was immunoprecipitable by an antibody that recognizes IGFBP-2. These results demonstrate that in adult rat serum and milk both IGF-I and IGF-II are present, with IGF-I being predominant. IGFBP are present in rat milk; the presence of IGFBP-2 in rat milk, but not in maternal serum, indicates that IGFBP may be synthesized within the mammary gland.

ISSN:0031-3998    

出版商:OVID    

年代:1991

数据来源: OVID