Decline of hepatitis a antibodies during the first 7 months of life in full-term and preterm infants

Summary In a previous study we have shown that transplacental transfer of hepatitis A antibodies to preterm infants does not differ from that observed in full-term infants. This follow-up study was designed to investigate the decline of hepatitis A virus (HAV) antibodies during the first 7 months of life in full-term and preterm infants, in an endemic region for hepatitis A. Two hundred and fifty newborn infants— 147 full-term and 103 preterm infants—were enrolled. Blood samples from the infants were taken at birth, and at 3 and 7 months of age. Anti-HAV titers were determined by ELISA. A concentration of ≥1∶20 mlU/ml was considered protective. Protective hepatitis A antibodies were present at birth in 48.3% of all full-term and 49.5% of all premature infants. By the age of 7 months only 13% of full-term and 21.7% of preterm infants still had protective titers. For the seropositive full-term infants the geometric mean titers (GMT) were 15,698, 6,107 and 345 at birth, 3 months and 7 months, respectively, and for preterm infants, 10,378, 2,307 and 225 at birth, 3 months and 7 months, respectively. Significant differences in GMT between preterm and full-term infants were found at birth and at 3 monts of age (P<0.05). In a region endemic for hepatitis A, low levels of anti-HAV at 7 months of age may justify trials on infant vaccination since this is the most effective way to eliminate hepatitis A from circulation.     

Variation of serum ferritin in low birth weight infants with maternal ferritin, birth weight and gestational age.

Serum ferritin measured at birth in 69 low birth weight infants proved to vary with gestational age as well as with weight. The increase with gestational age was even more striking when the infants small for gestational age were excluded. The relation between maternal and infant serum ferritin concentration was investigated for 2 groups of infants and their mothers (*preterm and term infants, respectively). Neither in preterm nor in term infants was the serum ferritin found to vary with that in the respective mothers.     

Evidence that maternal dengue antibodies are important in the development of dengue hemorrhagic fever in infants

To establish the role of maternal dengue-specific antibodies in the development of dengue hemorrhagic fever and dengue shock syndrome caused by dengue 2 virus in infants, we examined sera from mothers of infants and toddlers with dengue hemorrhagic fever or dengue shock syndrome and mothers of infants with pyrexia of unknown origin. The mean titers of hemagglutination inhibition, neutralization, and infection-enhancing activities against dengue 2 virus were not statistically different among the three groups. However, among infants who developed dengue hemorrhagic fever/dengue shock syndrome there was a strong correlation between the mothers' dengue 2 neutralizing titers and infant age at the time of onset of severe illness, where no such correlation was found among the other two groups. Furthermore, the actual age at which dengue hemorrhagic fever/dengue shock syndrome occurred in each infant correlated with the age at which maximum enhancing activity for dengue 2 infection in mononuclear phagocytes was predicted. This critical time for the occurrence of dengue hemorrhagic fever/dengue shock syndrome was observed to be approximately 2 months after the time calculated for maternal dengue 2 neutralizing antibodies to degrade below a protective level. In addition, sera of mothers of infants with dengue hemorrhagic fever/dengue shock syndrome enhanced dengue 2 virus infection to a slightly greater degree than did sera from mothers of infants with pyrexia of unknown origin and toddlers with dengue hemorrhagic fever/dengue shock syndrome. These data are consistent with the hypothesis that maternal dengue antibodies play a dual role by first protecting and later increasing the risk of development of dengue hemorrhagic fever/dengue shock syndrome in infants who become infected by dengue 2 virus.     

Perinatal bile acid metabolism: bile acid analysis of meconium of preterm and full-term infants

Background Our purpose was to evaluate the metabolism of bile acids in the fetus by analyzing the bile acid composition of meconium of preterm (less than 30 weeks’ gestational age) and full-term infants and comparing the results with the bile acid composition of feces of preterm and full-term infants 6 days after delivery. Methods The concentrations of individual bile acids were determined by gas chromatography-mass spectrometry after solvolysis and hydrolysis of bile acid conjugates. Results In meconium, the main bile acids were chenodeoxycholic and hyocholic acids. The main bile acid of feces from preterm infants at 6 days of age was the same as that of meconium. We also detected large amounts of secondary bile acids, especially deoxycholic acid and ursodeoxycholic acid. The ratio of cholic acid relative to chenodeoxycholic acid in meconium of preterm and full-term infants and in feces of preterm infants was less than 1, 0.36, 0.55, and 0.55, respectively. The percentage of chenodeoxycholic acid relative to total bile acids in meconium of preterm (P < 0.05) and full-term (P < 0.01) infants was significantly higher than that in feces of 6-day-old full-term infants. Conclusions More than half of the main pathway, at least, for bile acid synthesis in preterm infants may be the acidic pathway until the infants reach about 7 days of age.     

Gestational Maturation of Electrical Activity of the Stomach

Gestational maturation of gastrointestinalmotility is a key factor in readiness of the pretermneonates for enteral nutrition. Since gastric motilitymainly depends on the electrical activity of the smooth muscle cells, it was of interest to investigatethe developmental aspects of electrical activity of thestomach. The latter was recorded weekly throughcutaneous electrogastrography in 27 preterm infants (aged 29-34 weeks of gestation). Recordingswere done for 1 hr before and 1 hr after meal. Theelectrogastrographic variables measured were: percentageof normal gastric rhythm, i.e., 2-4 cpm; percentage of tachygastria (>4 cpm); the fed-to-fastingratio of the dominant electrogastrographic power; andthe instability coefficient of the dominant frequency.Data were compared with those measured in 10 full-term infants. Peaks of normal electricalactivity (2-4 cpm) were present in most of therecordings at all the gestational ages; however,percentages of both normal electrical rhythm andtachygastria in preterm infants were similar to thosemeasured in full-term infants (mean ± SD) (normalrhythm; fasting: 70.2 ± 3.8, fed: 72.2 ±5.0; tachygastria: fasting: 24.6 ± 4.0, fed: 19.1± 3.5) by 35 weeks of gestation (normal rhythm; fasting:67.5 ± 2.0, fed: 69.6 ± 4.4; tachygastria:fasting: 27.1 ± 4.0, fed: 25.6 ± 4.1). Thecoefficient of instability of the dominant frequency inpreterm infants was also similar to the value measuredin full-term infants by 35 weeks of gestation, whereasthe EGG power showed a significant increase in thepostprandial state at all the gestational ages. We conclude that a maturation pattern of theelectrical activity of the stomach can be detected bymeans of a noninvasive tool such as cutaneouselectrogastrography: a normal electrical rhythm can bedetected at very early gestational ages; however, thisactivity becomes dominant at around the 35 weeks ofgestational age. In preterm infants developmentalchanges of gastric electrical activity are a function of advancing postnatal age.     

Intrauterine growth is related to gestational pulmonary function in pregnant asthmatic women. Kaiser-Permanente Asthma and Pregnancy Study Group

Asthmatic mothers have been reported to deliver infants of lower mean birth weight than nonasthmatic mothers. This study examined the relationship between intrauterine growth and serial gestational spirometry in 352 pregnant asthmatic women who were prospectively treated and observed during pregnancy. A small (r = 0.11) but significant (p less than 0.04) direct correlation was demonstrated between infant birth weight and individual mean percent predicted FEV1 during pregnancy. In addition, lower maternal mean FEV1 during pregnancy was associated with increased incidences of birth weight in the lower quartile of the infant population (p = 0.002) and ponderal indices less than 2.2 (suggestive of asymmetric intrauterine growth retardation) (p less than 0.05), but not with increased incidences of preterm (less than 38 weeks) or low birth weight (less than 2,500 g) infants. Although lower mean birth weight occurred in infants of smoking compared with nonsmoking asthmatic mothers (p less than 0.02), the relationships of lower FEV1 to birth weight in the lower quartile of the population (odds ratio 3.0, p = 0.002) and ponderal indices less than 2.2 (odds ratio 2.8, p less than 0.05) were shown by multivariate analysis to be above and beyond the influence of smoking and also independent of the effects of age, parity, acute asthmatic episodes, and asthma medications. These data support the hypothesis that lower maternal gestational FEV1 during pregnancy is related to intrauterine growth retardation and suggest that the goals of gestational asthma therapy should include optimization of pulmonary function in addition to achievement of symptomatic control.     

Thyroid function in seventy-five healthy preterm infants thirty to thirty-five weeks of gestational age: a prospective and longitudinal study during the first year of life.

Thyroid function was evaluated in 75 healthy preterm infants, 30-35 weeks of gestational age. Serum thyrotropin (TSH), thyroxine (T(4)), triiodothyronine (T(3)), free T(4) (immunochemoluminescence) and reverse triiodothyronine (rT(3)) (radioimmunoassay) were measured in the mother and in the cord at delivery and in the preterm infants at 1 hour, 24 hours, 1 week, 3 weeks, 2 months, 4 months, 6 months, and 12 months of postnatal age. These values were compared to those of healthy full-term infants of the same postnatal age (22 at 24 hours from our hospital and from previously reported data at others times). Mean 24-hour TSH values were significantly lower (p < 0.001) in preterm than in full-term infant populations (12.38 +/- 6.13 microIU/mL versus 22.02 +/- 13.28 microIU/mL); however, all TSH values of preterm infants were in the range of the full-term values. Mean 24-hour free T(4) values were similar in preterm and full-term infants (1.88 +/- 0.46 ng/dL versus 2.01 +/- 0.54 ng/dL) and all preterm infants had free T(4) values within the range of those of full-term infants at 24 hours. Mean T(4) and T(3) values were significantly lower in preterm than in full-term neonates at 1 hour and 24 hours of age. Mean 24-hour rT(3) values were significantly higher in preterm than in full-term newborns. From 1 week onwards, all thyroid function values were in the same range in both populations. In conclusion, individual thyroid function was similar in healthy preterms and full-terms from the first 24 hours of life. Normative data in preterm infants during the first year of life applying the latest luminescence techniques currently used worldwide are reported.     

Prevalance of heparin-dependent platelet-activating antibodies in preterm newborns after exposure to unfractionated heparin.

Heparin is frequently used in preterm infants to prolong the patency of intravascular catheters. The aim of this study was to evaluate the prevalence of heparin-dependent platelet-activating antibodies in newborns. A cross-section of all preterm newborn infants expected to require heparin to maintain patency of a central venous access line were enrolled. A blood sample was obtained soon after birth before heparin exposure to exclude the possibility of placental transfer of maternal heparin-dependent platelet-activating antibodies. A second sample was obtained at termination of heparin use (mean duration of heparin exposure was 23 +/- 13 days; range, 6-67). Paired samples, at birth and after heparin use, were available for 42 infants with a mean gestational age of 27.8 +/- 2.2 weeks and birth weight of 1036 +/- 267 g. Thrombocytopenia developed in 57% (24/42) of the infants. None of these infants had clinical suspicion of thrombosis during the study period. The etiology of thrombocytopenia was confirmed sepsis in six, presumed sepsis in three, necrotizing enterocolitis in one, and unclear in 14 infants. Anti-heparin/platelet factor 4 antibodies measured using the standard assays for heparin-induced thrombocytopenia (two commercially available enzyme-linked immunosorbent assay tests and the functional platelet serotonin release assay) were negative on all infants. Although it could be related to the poor ability of these infants to mount an immunologic response, further research is necessary to fully understand this lack of response to heparin and to elucidate further the reasons for thrombocytopenia in very-low-birth-weight infants.     

The influence of prematurity and low birthweight on transplacental antibody transfer in Sri Lanka.

The influence of gestational age, the neonate's birthweight, and maternal age, weight, height and parity on transplacental antibody transfer was assessed in 141 mothers from Sri Lanka and their neonates. Paired blood samples were collected from the mothers and the umbilical cords of the newborns. The sera separated from these samples were categorized as: preterm but adequate birthweight (< 37 weeks' gestation and birthweight > or = 2500 g); term but low birthweight (> or = 37 weeks' gestation and birthweight < 2500 g); or term and adequate birthweight (> or = 37 weeks' gestation and birthweight > or = 2500 g). Neonatal and maternal sera were assessed, in ELISA, for specific IgG antibodies against measles virus (MeV), herpes simplex virus type-1 (HSV1), respiratory syncytial virus (RSV), varicella-zoster virus (VZV), tetanus toxoid (TT), diphtheria toxoid (DT), and Streptococcus pneumoniae (Pn) and Haemophilus influenzae type-b (Hib) capsular antigens. Placental antibody transfer to certain antibody specificities was significantly lower in preterm neonates than term neonates. Thus the ratios between geometric mean cord antibody levels and geometric mean maternal antibody levels (the antibody-transfer ratios) were lower in preterm sera than term sera, for MeV (1.51 v. 2.03; P = 0.03), HSV1 (1.29 v. 1.76; P = 0.04), VZV (0.96 v. 2.50; P = 0.01), TT (1.13 v. 1.33; P = 0.04), DT (1.03 v. 2.39; P = 0.02), Pn (0.68 v. 0.98; P = 0.01) and Hib (0.58 v. 0.98; P = 0.00). Geometric mean levels of antibody to MeV, VZV, TT, DT and Pn were also significantly lower in preterm neonates than term. Compared with the values for 'adequate-birthweight' sera, low birthweight was independently associated with significantly lower levels of antibody transfer, for MeV (with antibody-transfer ratios of 1.51 v. 2.03; P = 0.02), VZV (0.99 v. 2.50; P = 0.03), TT (1.01 v. 1.33; P = 0.04) and DT (1.16 v. 2.39; P = 0.04) and significantly lower levels of antibodies to MeV, HSV1, VZV, TT, DT and Pn in the neonates. Maternal age, weight, height and parity had no independent influence on placental IgG transfer for antibodies to any of the pathogens investigated. These results demonstrate that prematurity and low birthweight may influence the level of maternally acquired immunity in Sri Lankan neonates.     

Prevalence of pertussis antibodies in maternal delivery, cord, and infant serum

BACKGROUND: Passively acquired maternal antibodies protect infants from many pathogens. With increasing reports of infant pertussis, we evaluated pertussis antibodies in maternal-infant paired sera from 1999-2000. METHODS: Antibodies to pertussis toxin (PT), filamentous hemagglutinin (FHA), and fimbrial proteins (FIM) were measured by validated IgG-specific enzyme-linked immunosorbant assay (ELISA) in 64 maternal-umbilical cord serum pairs and in 61 of 64 infant sera. Geometric mean concentrations (GMCs) of pertussis antibodies and cord : maternal GMC ratios were calculated. RESULTS: Mean maternal age and gestation were 29.7 years (range, 19-42) and 39.3 weeks (range, 35.6-40.9), and 81% of mothers were white. GMCs of maternal antibodies at delivery (ELISA units/mL) were 2.4 for PT, 6.9 for FHA, and 13 for FIM. Cord GMCs were 169%, 178%, and 157% of maternal delivery values for PT, FHA, and FIM, respectively, demonstrating active placental transfer (P<.001). Pertussis-specific IgG values for each antigen decayed to below the threshold of detection by age 2 months. CONCLUSIONS: Despite efficient placental transfer, low maternal pertussis antibody levels and their rapid decay in infant sera leave infants with little humoral protection against pertussis. These data support the rationale for maternal or neonatal immunization, with acellular pertussis vaccines, to prevent life-threatening pertussis in early infancy.     

Immune response to hepatitis B vaccine in premature neonates.

The immunogenecity of a recombinant yeast-derived hepatitis B vaccine in 25 premature infants who were born to HBsAg negative mothers was studied. The gestational ages were 28-37 weeks and birth weights were 1300-2000 grams. Seroconversion occurred in 22 infants, the anti HBs titers varied between 50 and 13,470 IU/L (Geometric mean titer = 542 IU/L). Seroconversion rate = 88%. The response did not vary with gestational age, birth weight or illness status.     

Immune responses to measles and mumps vaccination of infants at 6, 9, and 12 months

Immunizing infants against measles at the youngest age possible has the potential to reduce morbidity and mortality. The ability of infants at 6, 9, or 12 months to respond to measles and mumps vaccines was evaluated by measuring T cell proliferation, interferon-gamma production, and neutralizing antibody titers before and after vaccination. Infants in all age groups had equivalent cellular immune responses to measles or mumps viruses, with or without passive antibodies when immunized. In contrast, 6-month-old infants without passive antibodies had low geometric mean titers of antibody to measles or mumps viruses and low seroconversion rates. Geometric mean titers of antibody to measles virus increased if infants were revaccinated at 12 months. Six-month-old infants had limited humoral responses to paramyxovirus vaccines, whereas cellular immunity was equivalent to that of older infants. T cell responses can be established by immunization with these live attenuated virus vaccines during the first year, despite the presence of passive antibodies.     

Sweat-testing in preterm and full-term infants less than 6 weeks of age

Our objective was to examine the characteristics of preterm and full-term infants < or = 6 weeks old that influence the success of obtaining sufficient sweat for diagnosis of CF, and corresponding sweat chloride concentrations. A retrospective chart review of 119 sweat tests was performed on 103 preterm and full-term infants < or = 6 weeks of age. Bivariate and multivariate regression analyses were used to determine the predictors of successful sweat testing and characteristics influencing sweat chloride concentrations. Adequate amounts of sweat (> or = 75 mg) were obtained for analysis in 73.8% of initial attempts in the infant group. The following characteristics were associated with increased odds of obtaining a quantity not sufficient (QNS) for sweat chloride concentration measurement: African-American race, infant weight < 2,000 g, preterm birth, and postmenstrual age (PMA) < 36 weeks. With a multivariable logistic model, the only significant predictors were African-American race (7.3, 2.4-21.7) and PMA < 36 weeks (17.9, 4.2-75.9). Sweat chloride concentration in non-CF individuals is inversely related to both gestational age and age at testing, and this effect is additive in a linear regression model. In conclusion, sweat collection can be reliably performed in infants > or = 36 weeks postmenstrual age, > 2,000 g, and > 3 days postnatal age. Maturational factors have a mild impact on sweat chloride concentration.     

Management of patent ductus arteriosus in preterm infants.

OBJECTIVE: To evaluate the incidence of symptomatic patent ductus arteriosus (PDA) in preterm infants, and the results of the intravenous indomethacine treatment and surgery. METHODS: Among 394 preterm infants (<37 weeks), symptomatic PDA was diagnosed by echocardiography in 51 babies and they were examined retrospectively. All infants were managed conservatively and then IV indomethacine was given to non-responders (n=30). Surgical closure was performed in 12 babies. RESULTS: The incidence of symptomatic PDA in preterm infants was 12.9%: median age: 3 days, mean birth weight: 1434+/-540 g (540-2900g) and mean gestational age (GA) 30.9+/-3.3 weeks (23-37 weeks). With indomethacine, ductal closure was achieved in 70% infants. Early clinical improvement was observed in all cases that underwent surgery and most of them had a low birth weight (<1500 g) and an early gestational age (<32 weeks). None of them died due to operation. CONCLUSION: The incidence of symptomatic PDA is high in preterm infants. Treatment with indomethacine improves ductal closure and is associated with few reversible adverse effects. In the other hand, early clinical improvement and high success rate were achieved after surgery. If indomethacine fails to achieve ductal closure, decision of surgery must be made immediately.     

Growth and differentiation factor 15 (GDF15) levels predict adverse respiratory outcomes in premature neonates

Growth and differentiation factor 15 (GDF15) is a stress-responsive cytokine, and its expression increases during inflammation, hyperoxia, and senescence. Significantly, GDF15 is secreted by the placenta, and maternal levels increase throughout pregnancy. Serum GDF15 level is a promising biomarker for many lung diseases like pulmonary hypertension and pulmonary fibrosis. However, circulating GDF15 levels in preterm infants and their role as a predictor of respiratory outcomes have not been studied. We hypothesized that GDF15 levels would increase with gestational age at birth, and that postnatal GDF15 will be correlated with adverse respiratory outcomes in preterm infants. Scavenged blood samples were retrieved from 57 preterm infants at five time points, from birth until 36-weeks postmenstrual age (PMA). GDF15 levels were measured using ELISA in 114 samples. We performed two-sample t-test, correlation and linear regression, logistic regression, and mixed-effects linear models for statistical analysis, and significance was identified when p < 0.05. Contrary to our hypothesis, for every 1-week increase in gestational age at birth, the predicted GDF15 level decreased by 475.0 pg/ml (p < 0.001). Greater PMA was significantly associated with lower serum GDF15 levels (p < 0.001). Interestingly, higher GDF15 levels were associated with a longer need for mechanical ventilation (p = 0.034), prolonged respiratory support need (p < 0.001), and length of hospital stay (p = 0.006). In conclusion, in preterm infants, GDF15 levels show an inverse correlation with gestational age at birth, with higher levels in more preterm babies, and levels trend down postnatally. Furthermore, longitudinal GDF15 levels through 36 weeks PMA predict adverse respiratory outcomes in preterm infants.     

Correcting for Ethnicity when Defining Large for Gestational Age Infants in Diabetic Pregnancies

The large-for-gestational-age (LGA) infant, defined as >90th birthweight percentile, is associated with mild disturbances of maternal glucose tolerance. In the UK the same birthweight percentile charts are used for all ethnic groups when assessing LGA infants. The influence of maternal hyperglycaemia on LGA infants of Asian (Indian Sub-continent) mothers in the UK is likely to be under-reported, as Asian birthweights tend to be lower than White/Europid birthweights. We assessed the number of LGA infants born consecutively to 21 Asian and 26 White/Europid mothers with gestational diabetes mellitus (GDM), delivered between 37 and 42 weeks gestation, and also in 34 Asian and 121 White/Europid mothers with a positive screening test for GDM but a normal 75 g oral glucose tolerance test (OGTT). Large-for-gestational-age infants were identified using both the standard UK percentile charts of the Medical Research Council and percentile charts constructed from 30418 Asian and 162477 White/Europid singleton births, delivered between 37 and 42 weeks gestation to non-diabetic mothers delivered in the North West Thames Region of England. The standard Medical Research Council percentile charts, compared with the ethnically derived charts, identified fewer LGA Asian (7/56 vs 15/56) but more White/Europid infants (33/147 vs 21/147). When correcting for ethnicity more Asian than White/Europid GDM mothers delivered LGA infants (9/21 vs 3/26, χ² = 4.76, p < 0.05). The maternal 2 h OGTT plasma glucose was a significant independent contributor to birthweight in the Asian (r ² = 0.319, p < 0.0005) but not the White/Europid infants, in whom gestational age and maternal height were significant independent contributors to birthweight (r² = 0.158, p < 0.0001). We conclude that ethnic influences are important when defining LGA infants and that mild disturbances of maternal glycaemia have a greater influence on the birthweight of Asian than White/Europid infants.     

Lack of Relationship between Birth Conditions and Allergic Disorders in Japanese Children Aged 3 Years

Background. The current cross-sectional study examined the associations between low birth weight (LBW), preterm birth, and small-for-gestational-age (SGA) and the prevalence of wheeze, asthma, and eczema in Japanese children aged 3 years. Methods. Study subjects were 2004 children. All data were obtained using a questionnaire. Outcomes were defined according to the criteria of the International Study of Asthma and Allergies in Childhood. Adjustment was made for sex, number of siblings, breastfeeding duration, paternal and maternal educational level, paternal and maternal history of allergic disorders, maternal smoking during pregnancy, secondhand smoke exposure at home, and gestational age at birth. Results. The prevalence of wheeze, asthma, and eczema in the previous 12 months were 22.1%, 9.0%, and 17.5%, respectively, and 8.4% were classified as LBW (<2500 g), 4.7% as preterm birth (<37 weeks), and 7.1% as SGA (<10th percentile). There were no significant associations between LBW, preterm birth, or SGA and the prevalence of wheeze, asthma, or eczema. A positive relationship between preterm birth and asthma was of borderline significance in children whose mothers had smoked during pregnancy (adjusted OR: 4.71 [95% CI: 0.97?21.39]), but not in those whose mothers had never smoked during pregnancy; the multiplicative interaction between preterm birth and maternal smoking during pregnancy with respect to asthma was significant (p = .04). Conclusions. The current study failed to detect significant associations between birth conditions and allergic disorders. Nevertheless, we did find evidence for an interaction between preterm birth and maternal smoking during pregnancy affecting asthma.     

Reduced lymphocyte-mediated antifungal capacity in high-risk infants

Premature and critically ill infants are highly susceptible to Candida albicans. This study evaluated the lymphocyte-mediated antifungal capacity of infants relative to birth weight, prematurity, and illness severity. Growth inhibition of C. albicans by lymphocytes from preterm and low-birth weight infants was significantly reduced, compared with full-term and normal-weight infants. Lymphocyte growth inhibition of C. albicans is dependent on cell adhesion to the fungus. Compared with full-term infants, lymphocytes from preterm infants had a reduced capacity to adhere to C. albicans. Furthermore, infants with greater severity of illness (score for neonatal acute physiology [SNAP], >or=10) exhibited significantly reduced lymphocyte-mediated antifungal capacity and fungal adhesion. Although gestational age, birth weight, and SNAP were significantly associated with lymphocyte-mediated growth inhibition and adhesion, stepwise regression analysis demonstrated that gestational age best predicted both lymphocyte growth inhibition of and adhesion to the fungus.     

福建地区新生儿刚地弓形虫感染血清学调查

目的 调查福建地区新生儿刚地弓形虫感染血清学阳性率,为制定先天性弓形虫病防控措施提供参考依据.方法 以2017-2018年福建地区出生的1 045例新生儿作为研究对象,其中早产儿387例、足月儿658例.采集新生儿脐带血,检测并比较早产儿和足月儿血清抗弓形虫IgG抗体阳性率.收集早产儿和足月儿母亲肘静脉血,检测并比较早...     

Rotavirus-specific helper T cell responses in newborns, infants, children, and adults.

An obstacle to developing a successful rotavirus vaccine has been the inability to consistently correlate the humoral immune response with protection against disease. Transplacental transfer of maternal rotavirus-specific antibodies may obscure the capacity to discriminate an active from a passively acquired humoral immune response in infants. In an attempt to circumvent this problem, an assay was developed to detect rotavirus-specific helper T cells among circulating mononuclear cells. Rotavirus-specific lymphoproliferative responses and rotavirus-specific neutralizing antibody titers in blood were determined in 11 mother/newborn pairs at the time of delivery and in 54 infants, children, and adults ranging in age from 16 days to 40 years. Only 1 of 11 infants tested between 16 days and 6 months of age had detectable rotavirus-specific helper T cell activity whereas 8 of 11 had circulating rotavirus-specific neutralizing antibodies. Acquisition of rotavirus-specific helper T cell activity over the first few years of life correlated with the age at which infants and young children are known to be infected with rotavirus. These findings support the hypothesis that detection of rotavirus-specific lymphoproliferative activity in infants may more accurately determine previous exposure to rotavirus than detection of rotavirus-specific antibodies.