摘要:

ABSTRACT.The ontogeny of human antibody responses to pneumococcal polysaccharide antigens was studied by determining whether the age at immunization affects the level and/or immunoglobulin isotype of antibody produced. Twenty-nine healthy infants between 2 and 18 months of age and 13 normal adults were studied. Responses were found to vary markedly with the age at the time of immunization and with the pneumococcal serotype tested. Three general patterns of isotype-specific antibody response were observed in the infants: a high response in IgG antibody occurred as early as 2 months of age following immunization with type 3 pneumococcal polysaccharide; little or no response was noted in either IgG or IgM antibody with types 6,18, and 19; and intermediate responses with IgM antibody increases greater than IgG increases were found for type 23. These data suggest that different factors control the immunologic response of infants to various pneumococcal polysaccharide serotypes following immunization at various ages.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.It is unclear whether placental xenobiotic metabolism can protect the human conceptus. In particular, the role of placental metabolism of toxic components of cigarette smoke such as polycyclic aromatic hydrocarbons (PAHs) is poorly understood. We hypothesized that increased aryl hydrocarbon hydroxylase (AHH) activity observed in placentas from smokers might help clear PAHs from maternal circulation and thereby prevent transplacental induction of AHH by PAHs. Our studies of AHH activity in human placentas and umbilical vein endothelium support this premise. While AHH activity was significantly increased in placentas from smokers compared with activity in placentas from nonsmokers, AHH activity in umbilical vein endothelium from these same pregnancies was unaffected by maternal smoking and remained low. In order to confirm that AHH present in endothelium was inducible, we also demonstrated dose-dependent increases in AHH activity in primary cultures of human umbilical vein endothelial cells exposed to PAHs. These findings may indicate first pass protection of the fetus by placental xenobiotic metabolism, or that endogenous factors suppress AHH induction in the fetus but not placenta.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.To explore the antisecretory effect of methylated casein (MC) cholera toxin was placed in isolated jejunal loops, andin vivowater fluxes were measured 3 h later in the presence or absence of MC. Secretion was observed in the loops filled with Ringer's solution only, but net absorption was observed in all 10 loops to which MC was added. Its actions was evident within 20 min, and was exerted directly on the luminal side of the epithelium. This response was dose-dependent and the antisecretory effect vanished after boiling MC and after ultrafiltration.In vitro,the antisecretory effect of MC consisted of reversing net Na and CI fluxes from secretion to absorption (δJNanet= 6.18 ± 1.25 and δJClnet= 5.10 ± 1.66 μ Eq.h−1cm−2). This change was due to the enhancement of mucosal to serosal flux. Transepithelial potential difference and tissue conductance did not alter. Interestingly, MC did not interfere with intestinal function in the absence of stimulation by cholera toxin. In the presence of cholera toxin, MC and glucose both stimulated ionic absorption by different mechanisms, MC stimulating neutral NaCl absorption, and glucose stimulating electrogenic Na absorption. MC did not alter basal adenylate cyclase activity but it inhibited the cholera toxin-stimulated increase in activity. The present results indicate that methylated casein inhibits water and electrolyte secretion induced by cholera toxin in rat jejunum. Its availability, low cost, and curative effect from the luminal side constitute compelling indications for further investigation.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.Using a specific and sensitive epidermal growth factor (EGF) radioimmunoassay, we have shown measurable quantities of EGF in mouse urine during the neonatal period. Sephadex G-50 column chromatography demonstrated the presence of a single immunoreactive component at the position defined by standard EGF (mol wt 6045). Comparison of urine urea nitrogen and urine EGF levels in neonatal and adult mice showed adult values to be 3− and 16-fold higher, respectively. Kidney weights relative to body weight were similar in newborn and adult animals while kidney EGF concentration per mg protein was 2.5-fold higher in the adult. The relative submandibular gland (SMG) weight was slightly higher in adult female mice than in the newborn, whereas SMG-EGF concentration was 15,000-fold higher in the adult than in the newborn.Thyroxine administration to neonatal mice from day 0 to day 6 increased urine EGF concentration 7-fold compared to control pups. Though the hormone treatment elicited a significant increase in relative SMG weight, its EGF concentration like that of the kidneys remained unchanged. The results suggest that urine EGF is subject to thyroid hormone modulation in newborn animals and that the changes in urine EGF concentration are independent of changes in SMG and renal EGF levels.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.Qualitative changes are known to occur in testicular steroidogenesis at birth as the testosterone peak is reached without significant elevation of basal luteinizing hormone in the 2nd wk of life. This study was designed to evaluate testicular activity prior to these changes. Pituitary-testicular function was studied by measuring serum gonadotropins and steroids after stimulation by gonadotropin-releasing hormone (GnRH) (one intravenous injection) and human chorionic gonadotropin (hCG) (three intramuscular injections). The subjects had minor genital anomalies; their ages ranged from 2 to 6 days. All had a strong luteinizing hormone response and a weaker follicle-stimulating hormone response to GnRH stimulation. hCG induced significant increases in serum pregnenolone, 17-hydroxyprogesterone, androstenedione, testosterone, and dihydrotestosterone. Serum estradiol and estrone did not change, and progesterone decreased. The results clearly show that the pituitary-testicular axis is functional neonatally. The responsiveness of the testis to hCG supports the assumption that the postnatal decrease of testicular steroids is due to the simultaneous disappearance of hCG from the circulation. The neonatal testis does not show any estradiol response to hCG, which is a feature typical of prepuberty.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.Cultured skin fibroblast homogenates from patients with Niemann-Pick disease Type C, were able to degrade sphingomyelin liposomes at a normal rate. Fibroblasts from patients with Niemann-Pick disease Types A and B were less active (0.08–0.55 versus 0.96–2.93 nmol/ h/mg). When fibroblasts were maintained in synthetic media (MCDB-104) devoid of fetal calf serum for a period of 21 days, sphingomyelinase activity measured at pH 3.8 increased in control and Niemann-Pick Type C (up to 15-fold) and in Niemann-Pick Type B (up to 3-fold) while Niemann-Pick Type A showed no significant increase in sphingomyelinase activity.Addition of a protein activator isolated from the spleen of a Type I Gaucher's disease patient stimulated a 2–7.5-fold increase in sphingomyelinase activity in normal, Niemann-Pick Type B and C fibroblasts, while under the same conditions the Niemann-Pick Type A fibroblast enzyme responded poorly.Our data show that the residual sphingomyelinase activity in Niemann-Pick Type A can be differentiated from that present in other phenotypic forms by its lack of response to the Gaucher activator. Furthermore, we can find no evidence to support the view that Niemann-Pick Type C sphingomyelinase differs from the normal enzyme in its response to Gaucher activator.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.Previous studies have shown a reduction in mortality rate from 90% to zero when neonatal rats, inoculated with group B streptococci (GBS) were injected with type-specific IgM antibody. However, in those studies, the antibody was administered simultaneously with the bacteria and at the same site, unlike the situation which would exist if antibody was used clinically to treat established infection. In the present experiments, we administered antibody intraperitoneally at various intervals following intrathoracic inoculation of GBS. When antibody was administered immediately after, or up to 2 h following bacterial inoculation, all animals survived. When antibody administration was delayed for 4, 5, or 6 h, survival rates of 92, 60, and 29% were observed. When antibody administration was delayed for more than 6 h, no survival occurred. Failure of antibody to protect animals from death coincided temporally with profound depletion of the neutrophil storage pool. In other experiments, depletion of the neutrophil storage pool was produced by a separate, noninfectious mechanism (subcutaneous implantation of sterile polyvinyl sponge discs) after which animals were inoculated with GBS. Antibody did not provide protection from death in animals with neutrophil storage pool depletion.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.An endogenous digoxinlike immunoreactive substance(s) (DLIS) exists in the serum of premature and full term infants not receiving digoxin. We followed serum changes in DLIS concentration sequentially over the first 14 postnatal days in 24 premature neonates who did not receive digoxin in the intensive care nursery. All infants had measurable levels (>0.6 ng/ml) of DLIS in their serum. There was a distinct peak in DLIS concentration in 19 of 24 infants occurring at 4 ± 1.6 (SD) days after birth (range, 1–8 days). No peak was found in five infants. The peak serum level of DLIS obtained in the first 8 days of life was negatively correlated with gestational age and birth weight.DLIS levels in amniotic fluid remained constant from 16 to 33 weeks of gestation but rose from 33 wk to term. DLIS concentrations in umbilical artery, umbilical vein, and maternal serum at normal full term delivery suggested that DLIS was of fetal origin. DLIS and digoxin concentrations are additive when present in the same serum sample if measured by standard radioimmunoassay methods.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.In this study, the experimental model of Wigglesworth was used to limit the maternal blood supply to the rat fetus and induce intrauterine growth retardation. The associated changes in plasma somatomedin activity, insulin, glucose, and cartilage metabolic activity are reported. The mean body weight ( ± SEM) of 108 fetuses in ligated uterine horns was significantly lower than that of 146 control fetuses (ligated, 2820 ± 50 mg; control, 3180 ± 50 mg;p< 0.001), as was mean nose-tail tip length (ligated, 55.6 ± 0.4 mm; control, 59.4 ± 0.3 mm;p< 0.001) and mean liver weight (ligated, 222 ± 5 mg; control, 274 ± 5 mg;p< 0.001). The uptake of [35S]sulfate by fetal costal cartilage in basal culture medium was significantly lower in growth-retarded fetuses than in controls. Plasma somatomedin activity measured by fetal rat cartilage bioas-say was significantly lower in growth-retarded than in control fetuses (p< 0.001). The growth-retarded fetuses were relatively hypoinsulinemic and hypoglycemic compared to control animals. These studies suggest that nutrient supply may become a limiting factor in the release of insulin and the circulating levels of somatomedin activity in the rat fetus, and hence in its growth.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACT.Postheparin plasma lipoprotein lipase and hepatic lipase activities of 11 preterm infants aged 1 to 4 days were measured 15 min after a heparin bolus of 100 IU/kg and during an exchange transfusion performed with fresh heparinized blood. Each infant had a birth weight (range, 1210–3490 g) appropriate for gestational age (range, 28–36 (wk). Eight of the infants (group 1) were in good clinical condition while three (group 2) suffered from septic shock. After the heparin bolus and during the exchange transfusion, lipoprotein and hepatic lipase activities in group 1 were higher than in term infants. In group 2, both lipase activities were extremely low after the heparin bolus but increased approaching the activities of group 1 during the exchange transfusion. Clearance of fat from the circulation is slower in preterm than term infants. This has been attributed to low lipoprotein lipase activity. Our results, however, indicate that lipoprotein lipase is not the reason for slow clearance of fat from the circulation in preterm infants except in septic shock.

ISSN:0031-3998    

出版商:OVID    

年代:1984

数据来源: OVID