ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The basal and gonadotropin-releasing hormone (GnRH) stimulated levels of LH were measured in 21 boys with delayed puberty using conventional RIA, mouse interstitial cellin vitrobioassay (B-LH), and a highly sensitive immunofluorometric method (F-LH). On the basis of subsequent clinical follow-up, the subjects were diagnosed as idiopathic constitutional delay of puberty (CD, n = 13) or hypogonadotropic hypogonadism (HH, n = 8). The basal RIA LH levels were similar in the two diagnostic groups (HH, 2.92 ± 0.76, CD 3.53 ± 1.37 IU/L). In contrast, the mean basal B-LH was significantly lower in boys with HH than with CD (1.10 ± 0.45versus2.91 ± 1.23 IU/L; p < 0.01). A similar finding was made by F-LH measurements which were clearly lower in the HH than the CD group (0.073 ± 0.04versus1.71 ± 0.97 IU/L, p < 0.01). Also upon GnRH stimulation (3.5 Mg/kg i.v.), the distinction between the CD and HH groups was better with the B-LH and F-LH measurements. The basal B/I ratio of the CD group (0.90 ± 0.43) was more than that of the HH group (0.42 ± 0.25, p < 0.01) and this ratio increased significantly (more than 2-fold, p < 0.01) during GnRH stimulation in the CD group, but not in the HH patients. Such differences were not found between the B/F ratios of the CD and HH groups. Measurements of basal and GnRH stimulated B- and F-LH levels clearly improved the distinction between CD and HH in comparison to the conventional RIA method, due to the low sensitivity and likely cross-reactions with some non-LH constituents of serum in the latter assay. This problem is, to a great extent, eliminated by better sensitivity and specificity of B-LH and F-LH measurements. For the same reasons, the difference in B/I ratios between the CD and HH samples, and the increased B/I ratio after GnRH stimulation in the CD group, were not observed in B/F ratios. In conclusion, the measurements of basal and GnRH-stimulated concentrations of serum B-LH and F-LH clearly improve the differential diagnostics between CD and HH. The discrepancies measured between the B/I and B/F ratios in these samples call for reevaluation of the bio/immuno ratios of circulating LH.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Pulsatile secretion of LH and FSH was examined in 10 prepubertal (aged 4.5–12.9 y) and seven early pubertal (aged 12.8–14.5 y) boys with ultrasensitive (0.019 and 0.014 IU/L time-resolved immunofluorometric assays. Plasma LH and FSH levels were measured every 15 or 20 min for 6 h during the day and night. The lowest mean LH level in a prepubertal boy was 0.02 IU/L and in eight other prepubertal boys mean LH levels were less than 0.4 IU/L. In early pubertal boys the mean LH levels ranged from 0.3 to 6.5 IU/L. The difference in mean FSH level between prepubertal (0.61 IU/L) and early pubertal boys (1.85 IU/L) was smaller than the difference in LH level. All boys had significant LH and FSH pulses. The LH interpulse interval was 135 ± 86 min (mean ± SD) and 76 ± 65 min for the prepubertal and pubertal boys, respectively (p < 0.01). For FSH, the respective values were 150 ± 122 and 221 ± 157 min (p = NS). The mean LH pulse amplitudes were 11-fold greater in the early pubertal boys than in the prepubertal boys, whereas the mean FSH pulse amplitudes were similar between the two groups. The present method shows that the mean LH levels in prepubertal boys are much lower, and the increase during puberty larger, than previously reported. The increase is apparently due to increased pulse frequency and amplitude. The increase in mean FSH level is smaller and evidently not caused by an increase in pulse frequency or pulse amplitude.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Red blood cell (RBC) deformability in rats of various ages was assessed by filtration (3 μm Nuclepore membranes). Neonatal rat RBC (1 d old) had lower filter-ability, both in terms of RBC incremental volume (9.97 ± 1.85 versus 0.33 ± 0.28 nL at 180 d of age, mean ± SD, p < 0.001) and the number of filter clogging particles (25.7 ± 3.1 versus 18.9 ± 3.4 RBC × 103/s, p < 0.001). The lower filterability correlated with a larger RBC volume (169 ± 12.6versus69 ± 3.2 μm3, pversus2.84 ± 0.05 μm, p < 0.001). Almost all of the neonatal RBC had a minimum cylindrical diameter exceeding the 3 μm nominal pore size of the filters. The calculated resistance to initial folding was also significantly greater, as indicated by a static bending analysis of initial deformation. However, when the larger size of neonatal RBC was taken into consideration, and thus their greater projected area on which forces are applied, they appear to be at least as deformable as the adult type RBC. This finding may explain the contradiction between RBC filtration experiments and other approaches based on RBC deformations in shear flow, which have been unable to detect a hampered flexibility of neonatal RBC. In view of the more pronounced differences between neonatal and adult RBC in rats than in human subjects, the rat is an interesting model for studying this physiologic phenomenon in newborns.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

IL-6 is a cytokine with a wide variety of influences on the cells involved in immune and inflammatory responses. Defective production of IL-6 may be partly responsible for the impaired immune defense and inflammatory response often observed in the neonatal period. In our study, we used whole blood culture to examine the capacity of neonatal leukocytes to produce IL-6 in response to various stimuli. IL-6 activity was evaluated by growth promoting assay using an IL-6-dependent murine hybrid-oma clone. IL-6 activity was undetectable in fresh or unstimulated blood obtained from both newborns and adults. In contrast, incubation of whole blood with lipo-polysaccharide or concanavalin A resulted in marked IL-6 activity. After stimulation, IL-6 activity was induced as early as 2 h after culture and increased with time, reaching a plateau at around 12 h. Comparative examinations suggested that the IL-6 activity induced in neonatal blood on stimulation was similar to that seen in stimulated adult blood. Neutralization experiments with anti-IL-6 anti-serum confirmed the presence of IL-6 proteins in the stimulated blood, and induction of cellular IL-6 mRNA was demonstrated in the stimulated blood as well. In addition, immunocytochemical observations suggested that the major IL-6 producing cells in the stimulated blood may be monocytes. The results suggest that the production of IL-6 in response to specified stimuli is normal at birth.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Sera from obligate heterozygotes for deficiency of the C8β subunit of the eighth component of human complement (C8) were analyzed for the molecular composition of C8. The C8α-γ and C8β subunits were separated by SDS-PAGE, visualized by immunoblotting, and the resulting bands were quantitated by laser densitom-etry. The laser densitometric absorption data were set to 100 arbitrary units (AU) for both subunits of pooled normal human sera. The AU values of individual normal sera ranged from 45 to 150 AU for C8α-γ (median 99 AU) and from 45 to 140 AU for C8β (median 101), whereas the C8α-γ/C8β-ratio varied from 0.7 to 1.4. Sera from C8β-deficient heterozygotes differed, as expected, from the normal sera for the markedly reduced levels of C8β (20 to 90 AU, median 55 AU) and for the higher C8α-γ/C8β-ratio (1.3 to 3.5). High voltage agarose gel electrophoresis was used to separate free and C8β-bound C8α-γ. The migration of free and C8β-bound C8α-γ subunit was checked by hemolytic overlay gels and by second dimension SDS-PAGE and immunoblotting. Immunochemical evaluation of C8α-γ using this system revealed about 5–14% free C8α-γ in sera with normal C8 and higher levels, from 33–71%, in the C8βD heterozygous sera. Functional analysis confirmed the substantial increase of free C8α-β in the heterozygous group. We conclude that the C8 in C8βD heterozygous sera is characterized by increased amounts of free C8α-γ due to reduced concentrations of the C8β subunit. This finding may help to identify individuals heterozygous for C8β deficiency.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The development of the intestinal mucosal immune barrier is an important protective adaptation for postnatal life. The distribution and phenotype of T and B lymphocytes in human fetal intestine and lymphoid tissues have been characterized and compared to the distribution and phenotype of lymphocytes in postnatal intestine. The characterization of lymphocyte phenotype and MHC class II antigen distribution was done using MAb and an avidinbiotin complex immunohistochemical staining technique. Intraepithelial lymphocytes were occasionally present in fetal intestine and were primarily CD3+, CD8+. T lymphocytes were readily identified in the lamina propria of fetal intestine, but most were clustered in lymphoid aggregates. Cells identified by anti-IgA1and anti-IgA2were the most numerous cells of B cell lineage in the lamina propria of postnatal intestine, whereas IgM+and IgD+lymphocytes predominated in fetal tissues. However, IgA-bearing cells were identified in lymphoid aggregates of the intestine or spleen of some fetuses. This finding suggests that B lymphocytes can undergo Ig switchingin utero. Additionally, fetal intestinal epithelial cells did not express MHC class II antigens, unlike some postnatal intestinal tissues. It is possible that postnatal events such as antigen exposure may be important for the induction of these class II antigens on intestinal epithelial cells.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The impact of early postnatal protein-energy malnutrition and of 4, 7, and 14 d of nutritional rehabilitation on small intestinal growth, development, structure and function was examined in 28-, 32-, 35-, and 42-d-old infant rabbits. Malnutrition was induced by litter expansion 7 d postpartum and, in randomly selected malnourished animals, refeeding was begun at weaning, 28 d. Results are compared toad libitumfed dietary controls. Malnutrition altered the small intestine of the developing rabbit, as evidenced by: 1) reduced jejunal and ileal mass as shown by decreased mucosal wt, protein, and DNA content; 2) depressed epithelial proliferation and enterocyte migration along the crypt-villus axis; 3) delayed epithelial maturation as measured by mucosal enzyme activities; and 4) enhanced glucose-stimulated Na+transport. Refeeding stimulated rapid and complete recovery, as evidenced by: 1) restoration of jejunal and ileal mucosal mass within 4 d; 2) enhancement of epithelial renewal and enterocyte migration by 7 d; and 3) complete return of the normal pattern of mucosal enzymes by 14 d. With 7 d of refeeding, glucose-stimulated Na+transport was downregulated to the level of dietary controls. We conclude that early postnatal protein-energy malnutrition has a severe impact on small intestinal growth, development, structure, and function. Furthermore, a brief period refeeding induced a rapid and complete recovery of these parameters.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The molecular forms of lactoferrin (LF) were examined in stools and urine collected at 2.5 or 5 wk of age from very low birth wt infants fed either a cow's milk formula or a fortified human milk preparation. LF was not found by Western blotting in excreta from infants fed cow's milk. In contrast, intact and fragmented forms of IF were detected in stools and concentrated urine of each infant who received human milk. Only intact LF was detected in the fortified human milk preparation, whereas many types of LF fragments were present in the stools and urine. The approximate molecular wt of the most prominent fragments were 44, 38, 34, and 32 kD. However, the stools also displayed lower molecular wt fragments that were not found in urines of those infants. The LF fragments in those excreta were similar in size to those producedin vitroby limited digestion of apo-LF with trypsin. Furthermore, fragments produced byin vitroproteolysis were immunoreactive in an ELISA for LF. Thus, the fragments of LF in stools of very low birth wt infants fed human milk appeared to be produced byin vivoproteolysis, and the close resemblance between the LF fragments in the stools and urine suggests that the urinary LF fragments originated in the gastrointestinal tract. It remains unclear, however, whether the whole LF molecules that were fragmented were derived solely from ingested LF in human milk or in part from LF produced by the infant in response to human milk feedings.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Extracellular volume can be estimated from the distribution volume of sucrose (Vdsucrose). The purpose of this study was to establish sucrose pharmacokinetics in preterm infants <1500 g compared to children and adults and to define an optimal sampling scheme. In five preterm infants, 10 children, and five adults Vdsucrose after a single injection was calculated with the two-compartment model (VdSucrose-TCM) and with the one-compartment model applied only to the elimination phase of the same concentration-time curve (Vdsucrose-OCM). In preterm infants Vdsucrose-TCM was 417 ± 45 mL/kg (mean ± SD). Vdsucrose-OCM was only 3.0 ± 2.3% higher, because sucrose elimination half-life was on average 250 times longer than distribution half-life. Therefore VdSucrose-OCM, requiring only four blood samples between 2 to 5 h after injection, gave an adequate estimate of Vdsucrose in preterm infants <1500 g. Vdsucrose-TCM in children and adults was 188 ± 26 and 189 ± 17 mL/kg, respectively. Vdsucrose-OCM was 10 to 65% higher. Therefore, in children and adults only Vdsucrose-TCM gives a reliable estimate of Vdsucrose. This requires 10 to 15 blood samples. The reduced sampling scheme was used in an extension of the study of preterm infants including five additional infants. Vdsucrose-OCM in the preterm infants was 462 ± 47 mL/kg at birth and 425 ± 46 mL/kg at maximal postnatal wt loss. Postnatal wt loss (mean −83 ± 44 g) was not significantly different from postnatal reduction of Vdsucrose-OCM (mean −82 ± 56 mL), suggesting that postnatal wt loss mainly represents extracellular fluid loss.

ISSN:0031-3998    

出版商:OVID    

年代:1990

数据来源: OVID