Oxidative burst and phagocytosis of neonatal neutrophils confronting Candida albicans and Candida parapsilosis

Background

Candida albicans and Candida parapsilosis are important causes of sepsis among premature neonates. The neutrophil is a key element in the control of Candida infections, yet specific neutrophil mechanisms that may contribute to the susceptibility of the premature neonate to candidiasis are not well understood.

Aims

The hypothesis for this study is that neonatal neutrophils have a developmental deficiency in their capacity to generate an oxidative burst in response to Candida species.

Study design

Neutrophils were isolated from cord blood of term and preterm infants and from peripheral blood of adult volunteers. Neutrophils were exposed to Candida species, and assays of oxidative burst and phagocytosis were conducted.

Results

Oxidative burst of neutrophils from term and preterm (22-29 weeks) neonates exposed to C. albicans hyphae was similar to adult neutrophils. No detectable burst was induced in either group by exposure to C. parapsilosis yeast, and was attenuated by exposure to C. albicans yeast. Because no deficiency in oxidative burst was seen, phagocytosis was also studied. Phagocytosis of unopsonized C. albicans yeast was low in both adult and neonatal neutrophils (10-12%), but was more efficient with C. parapsilosis as target (76-88%). Neutrophils from both term and preterm infants were capable of phagocytosis equivalent to adults.

Conclusion

A deficiency in generation of an oxidative burst or phagocytosis may not contribute to the increased susceptibility of preterm neonates to infections with Candida.     

Effects of granulocyte colony-stimulating factor on neutrophil adhesive molecules in neonates

BACKGROUND: Term and preterm neonates experience quantitative and qualitative neutrophil deficiencies resulting in part from decreased production of granulocyte colony-stimulating factor (G-CSF). In adults, G-CSF improves neutrophil function by up-regulating adhesion molecules. PATIENTS AND METHODS: To evaluate the effects of G-CSF on neonatal neutrophil adhesive phenotypes, cord blood samples were incubated with G-CSF or phosphate-buffered saline and stimulated with N-formyl-methionyl-leucyl-phenylalanine (FMLP), and adhesion molecules were evaluated by flow cytometry. RESULTS: In term and preterm neutrophils, G-CSF incubation increased beta2-integrin expression significantly compared with baseline and to a greater extent than observed in adult neutrophils. With FMLP stimulation, beta2-integrin expression increased even more in the G-CSF group. L-selectin expression decreased after G-CSF incubation and decreased even more with FMLP stimulation in the G-CSF group compared with the phosphate-buffered saline group in term and preterm samples, but not in adult samples. CONCLUSIONS: The data show that G-CSF increases expression of beta2-integrin and decreases expression of L-selectin on unstimulated and stimulated term and preterm neonatal neutrophils in vitro. Further study is required to determine whether G-CSF improves neonatal neutrophil function.     

Granulocyte function in premature infants before the 34th week of pregnancy and in mature newborn infants]

BACKGROUND: Preterm and term neonates have an increased risk to develop severe bacterial infections. Impairment of neutrophil function may be responsible for this increased risk. Other diseases related to prematurity like retinopathia of prematurity (ROP) or broncho-pulmonary dysplasia (BPD) on the other hand may be due to poorly controlled O2-radical production. PATIENTS AND METHODS: Blood samples of 112 premature (34 weeks of gestation and older) and term neonates were analysed. Blood samples of 23 healthy adults (18 to 50 years old) served as controls. O2-radical production and phagocytosis of neutrophils were determined by flow cytometry, using a commercial test system. RESULTS: Under the experimental conditions applied, the capacity to produce O2-radicals following vigorous stimulation (E. coli) is comparable between neutrophils of preterm/term neonates and healthy adults. However, unstimulated or weakly stimulated (fMLP) neutrophils of preterm and term neonates show a statistically higher O2-radical production as neutrophils of the control group. The production of oxygen radicals increases during the first 10 days of the life. The capability of neutrophils to phagocytose E. coli is significantly lower in newborns (preterm and term) compared to the adult controls. CONCLUSIONS: The values reported here for phagocytosis and O2-radical production utilizing a commercially available test system may serve as "preliminary normal values" for neonates. No differences were found between the groups of neonates with and without infection. Impaired neutrophil-phagocytosis possibly contributes to the increased risk of preterm and term neonates to acquire bacterial infections. The increased spontaneous O2-radical production, on the other hand, may play a role for the development of so called "free radical diseases" such as ROP or BPD. However, our results cannot add further proof to this hypothesis.     

Human neutrophil lipocalin: normal levels and use as a marker for invasive infection in the newborn

AIM: To evaluate human neutrophil lipocalin (HNL) as a marker of neonatal invasive infection and determine the normal serum levels of HNL in newborns. METHODS: HNL is released from neutrophil granulocytes and is regarded as a specific marker of neutrophil activity. In 81 newborns < or = 28 d of age with signs of infection on a total of 87 occasions, HNL and C-reactive protein (CRP) were measured at inclusion and on the three following days. As controls, term healthy newborns were recruited at birth (cord blood, n = 45) and at ages 3-5 d (n = 46). Serum HNL was measured by a radioimmunoassay. RESULTS: 25/87 episodes were classified as infection and 62 as non-proven infection. HNLmax was significantly higher in the infected group (mean 587.6 microg/l) than in the non-proven infected group (mean 217.7 microg/, p < 0.001). HNL peaked at inclusion, 1 d earlier than CRP. In the healthy controls. HNL was the same at 3-5 d of age as at birth (mean 82.4-81.7 microg/l) and similar to normal adult levels. CONCLUSIONS: The release of HNL is not increased in healthy newborns at birth, but neonatal neutrophils rapidly release HNL upon microbial stimulation in vivo. HNL might be useful as an early marker of neonatal infection.     

Neutrophils from term and preterm newborn infants express the high affinity Fcgamma-receptor I (CD64) during bacterial infections.

The high affinity Fcgamma-receptor I (FcgammaRI, CD64) is normally expressed only to a very low extent by neutrophils. During bacterial infections, however, neutrophils from adult patients significantly increase their expression of FcgammaRI. Stimulation through FcgammaRI is a highly effective way to improve various aspects of neutrophil function, including phagocytosis. In our study the expression of FcgammaRI on neutrophils from preterm (n = 9) and term (n = 3) newborn infants, children (n = 14), and adults (n = 6) during the early phase of an acute bacterial infection was investigated. Our results showed that neutrophils from newborn infants with bacterial infection expressed FcgammaRI to a significantly higher extent than both noninfected preterm (p < 0.001) and term (p < 0.001) newborn infants and that neutrophils from preterm neonates expressed FcgammaRI to the same extent as neutrophils from term neonates and older infants, children, and adults. No difference in the neutrophil cell surface expression of FcgammaRI during bacterial infections was found among newborn infants, children, and adults. Expression of FcgammaRI probably represents an important mechanism to improve neutrophil phagocytosis as well as other aspects of neutrophil function during bacterial infections, especially in preterm infants. Our study indicates that measurement of cell surface expression of FcgammaRI on neutrophils could be a useful indicator of severe bacterial infections in preterm and term neonates, as well as in older children and adults.     

Glutathione recycling and antioxidant enzyme activities in erythrocytes of term and preterm newborns at birth

We previously demonstrated a high susceptibility of neonatal red blood cells (RBC) to oxidative stress at birth. The aim of this study was to compare the RBC antioxidant capacity and redox cycle enzyme activities as well as glutathione (GSH) recycling in full-term and preterm infants at birth and in normal adults. GSH and GSH disulfide (GSSG) concentrations, GSH/GSSG ratio, and the activities of glucose-6-phosphate dehydrogenase (G-6-PDH), GSH peroxidase, GSH reductase (GR), catalase (CAT), superoxide dismutase (SOD), and hexokinase (HK) were measured in RBC of 25 healthy adults and 56 newborns (23 term, 33 preterm) at birth. The GSH recycling was measured in adult and newborn RBC exposed to oxidative stress (1 mM tert-butylhydroperoxide). The RBC of term and preterm babies showed higher GSH, GSSG, G-6-PDH, GR, and HK levels/activities and lower GSH/GSSG ratios and higher GSH-recycling rates than those of adults. In preterm babies significant correlations were found between G-6-PDH and CAT, GSH, GSH/GSSG ratio, and GSSG (r = -0.67, r = 0.71, r = -0.66, p < 0.01; r = 0.71, p < 0.05, respectively). In term newborns, statistically significant correlations were observed between G-6-PDH and CAT, SOD, and GSH (r = -0.65, r = -0.65, r = -0.69, p < 0.01, respectively). The results indicate the central role of the G-6-PDH activity in antioxidant defenses. We speculate that preterm babies have prompter involvement of antioxidant defenses than term babies.     

Increased respiratory burst and increased expression of complement receptor-3 (CD11b/CD18) and of IL-8 receptor-A in neutrophil granulocytes from newborns after vaginal delivery

To study neutrophil activation in cord blood as a function of the mode of delivery, we performed analysis of the function of neutrophil granulocytes by assessing their ability to produce reactive oxygen products (ROP) as well as neutrophil cell surface expression of CD11b/CD18 and interleukin (IL)-8 receptors quantified with flow cytometry. Plasma levels of granulocyte colony-stimulating factor (G-CSF) were measured using an immunoassay. Neutrophil granulocytes were derived from cord blood of term newborns delivered vaginally (n = 20) and by cesarean section (n = 10), and, for comparison, from adult peripheral blood (n = 15). Blood neutrophil counts and the capacity of neutrophil granulocytes to produce ROP in response to stimulation with Escherichia coli was increased in newborns after vaginal delivery as compared to newborns delivered by cesarean section. The level of expression of the adhesion molecule/complement receptor CD11b/CD18 and the chemokine receptor IL-8 RA was also higher after vaginal delivery. Plasma concentrations of G-CSF in cord blood of newborns were higher than those of adults with no difference detectable between vaginal delivery and cesarean section. The data demonstrate a higher functional responsiveness and a higher expression level of functionally important receptors in neutrophils after vaginal delivery possibly due to activation of neutrophil granulocytes during labor.     

Hyperglycaemia as a possible marker of invasive fungal infection in preterm neonates

AIM: The incidence of invasive fungal infection in preterm newborns is rising steadily. Early recognition and treatment are imperative, but diagnosis is difficult as data from microbiological investigations are often poor, and clinical and laboratory signs do not help in differentiating bacterial from fungal infections. We evaluated whether glucose intolerance could represent a possible surrogate marker predictor of invasive fungal infection in preterm neonates. METHODS: We performed a case-control study on neonates with birthweight less than 1250 g admitted to our tertiary-level unit during the years 1998-2004 (n = 383), comparing those with invasive fungal infection (n = 45, group A) to matched controls with late-onset sepsis caused by bacterial agents (n = 46, group B). We investigated in both groups the occurrence of hyperglycaemia (serum glycaemia > 215 mg/dl, i.e. 12 mmol/l) in the first month of life, and its temporal relationship with the episodes of sepsis. RESULTS: Hyperglycaemia occurred significantly more often in group A (21/45, 46.6%) than in group B neonates (11/46, 23.9%) (OR 1.95, 95% CI 1.235-4.432, p = 0.008). Moreover, in 19 of 21 (90.4%) neonates with hyperglycaemia in group A, the carbohydrate intolerance episode typically occurred 72 h prior to the onset of invasive fungal infection; in contrast, no temporal relationship was found in neonates with bacterial sepsis (p = 0.002). Correction of hyperglycaemia was successfully achieved in all neonates of both groups, with no significant differences in the number of days of insulin treatment needed to normalize glycaemia (p = 0.15). CONCLUSIONS: Hyperglycaemia is significantly more frequent in neonates who subsequently develop fungal rather than bacterial late-onset sepsis, with a typical 3-d interval. We suggest that a preterm neonate whose birthweight is less than 1250 g in its first month of life should be carefully evaluated for systemic fungal infection whenever signs of carbohydrate intolerance occur.     

Granulocyte-macrophage progenitor cells in term and preterm neonates

In groups of adults, and term and preterm neonates, we determined: the blood concentration, the proliferative rate, and the variety of progeny of committed granulocyte-macrophage progenitor cells (CFU-GM). In five of eight term neonates and in all premature infants, a potentially significant limitation of neutrophil production was detected. Unlike the slowly proliferating CFU-GM present in the blood of healthy adult subjects (7% thymidine suicide, range 0% to 32%), the circulating CFU-GM in the premature subjects were proliferating at a near maximal rate (55%, range 40% to 75%, P less than 0.001). Because CFU-GM proliferation is nearly maximal in the baseline, noninfected state, neonates may have restricted ability to increase neutrophil production from CFU-GM during times of increased neutrophil need, such as during bacterial infection. Such inability may predispose neonates to exhaustion of the neutrophil supply during bacterial infection.     

Autonomic cardiac control of very preterm newborns: a prolonged dysfunction

BACKGROUND: Autonomic nervous system (ANS) activity is fundamental to infant health. ANS activity of preterm newborns seems to be reduced at term equivalent age, but follow-up of ANS activity has rarely been performed in that population during the weeks after birth. The aim of the study was to perform such a follow-up in preterm newborns of different gestational ages, up to their term equivalent ages. METHODS: Prolonged electrocardiographic recordings were prospectively performed in a group of 39 premature newborns, each week, up to term equivalent age before discharge. Control values were obtained from a group of 19 full-term newborns, recorded at the first week of their life. ANS indices were calculated from recordings during quiet sleep periods by spectral-domain analysis (Fourier transform): Ptot (total power), VLF (very low-frequencies), LF (low-frequencies), HF (high-frequencies), LF/HF ratio, LFnu (normalized low-frequencies) and HFnu (normalized high-frequencies) values. RESULTS: Ptot, VLF, LF and HF were significantly lower in the preterm group at birth compared to the control group, while LFnu, HFnu and LF/HF ratio were not significantly different. The results were similar when comparing the control group to any ANS values at a given post-natal corrected age of preterm newborns. Furthermore, preterm newborns did not demonstrate any significant increase in ANS values from birth to theoretical term. CONCLUSION: The finding of substantial reduced ANS activity and failure of maturation in preterm infants up to term equivalent age needs confirming by other research groups, and mechanisms and implications for infant health explored.     

Theophylline alters neutrophil function in preterm infants

Theophylline (1,3-dimethylxanthine), which is often prescribed to premature infants to treat apnea, acts, in part, by altering the metabolism of cyclic AMP. This second messenger plays a role in signal transduction mediating neutrophil functions, including respiratory burst, chemotaxis, and motility. We hypothesize that theophylline causes reduced respiratory burst activity, chemotaxis, and random motility in neutrophils. In these studies, we aim at determining the effects of theophylline on neutrophil function in vitro in cells from preterm and full-term infants and adults as well as on neutrophils obtained from premature infants receiving theophylline treatment. Neutrophils were obtained from 20 preterm infants, 16 full-term infants, and 14 adults. Chemiluminescence, chemotaxis, and random motility were measured after exposure of these cells to theophylline in vitro (0- 84 micromol/l or 0-15 microg/ml). In addition, these neutrophil activities were correlated with serum theophylline levels in 13 preterm infants receiving theophylline treatment for 72 h. Neutrophils from premature infants, term infants, and adults all displayed reduced chemiluminescence, chemotaxis, and random motility at 84 micromol/l (15 microg/ml) of theophylline in vitro. The relative reductions were greatest in cells from premature infants (p < 0.01). A level-dependent reduction in these activities was also noted in neutrophils from preterm infants with serum theophylline levels >46 micromol/l (8.2 microg/ml; p < 0.001). In contrast, lower theophylline concentrations (about 28 micromol/l or 5 microg/ml), either in vitro or in vivo, caused significant increases in neutrophil activities. Theophylline concentrations in the high therapeutic range (84 micromol/l or 15 microg/ml) cause dose-dependent reductions in neutrophil chemiluminescence, chemotaxis, and random motility. Cells from preterm infants are particularly sensitive to this effect. In contrast, theophylline concentrations in the low therapeutic range (28 micromol/l or 5 microg/ml) cause increased neutrophil activities. Altered neutrophil activity in newborns related to theophylline treatment may affect the infants' response to infection as well as the incidence of inflammatory diseases.     

CD64 (Fcgamma receptor I) cell surface expression on maturing neutrophils from preterm and term newborn infants

BACKGROUND: The expression of CD64 (FcgammaRI) is increased from an almost negligible to a marked level on neutrophils in patients with bacterial infections. CD64 expression on neutrophils might therefore be a potential candidate for the diagnosis of bacterial infections in infants. AIM: This study was performed to monitor changes of neutrophil expression of CD64 during the postpartum period to further evaluate the usefulness of this analysis. The possible influence on the expression of this receptor by other factors was also investigated, including respiratory distress syndrome (RDS) and preterm rupture of the membranes (PROM). METHODS: Cell surface expression of CD64 on neutrophils from preterm and term newborn infants and healthy adults was analysed by flow cytometry. The expression of the other Fcgamma receptors, CD32 and CD16, and the complement receptors CD11b/CD18 and CD35 was also analysed for comparison. RESULTS: Neutrophils from preterm newborn infants showed a moderately increased level of CD64 expression that, during their first month of life, was reduced to the level observed on neutrophils from term newborn infants and adults. In contrast, the level of neutrophil expression of CD32 and CD16 was significantly lower in preterm than term newborn infants and adults. Neutrophils from all groups indicated similar levels of CD11b expression, but the expression on neutrophils from newborn infants increased after birth. CONCLUSION: Our results showed that neutrophil expression of CD64 is moderately increased in preterm newborn infants at birth. It seems not to be influenced by RDS, PROM or other factors related to preterm birth but by bacterial infection.     

Skin conductance and behaviour during sensory stimulation of preterm and term infants

Aim: To investigate the responses to painful and tactile stimulation in preterm and term infants in terms of changes in the plantar skin conductance activity (SCA) and behavioural state. Plantar SCA reflects activity in the sympathetic nervous system. Design: The plantar SCA and behavioural state in response to nociceptive (the heel prick for blood samples, or immunization) and tactile (routine nursery handling) simulation was recorded in four different groups of infants (n=71): Preterm and term neonatal infants (defined here as up to 1 week old), and preterm and term infants in the postneonatal period. Results: The preterm infants had significant increases in all skin conductance variables during both tactile and nociceptive stimulation (p<0.02), except for wave amplitude when newborns were heel pricked. The term infants displayed a more varied picture, but both the number and amplitude of the waves increased significantly during both procedures in the newborn groups, while the postneonatal groups only showed significant increases in wave amplitude during nociceptive stimulation (p<0.05). Tactile stimulation of the preterm newborn infants produced significantly higher increases in SCA than nociceptive stimulation (p<0.01), while the behavioural state was highest during nociceptive stimulation (p<0.05). A gradual change in this relation was seen with advancing total age. Conclusion: Non-painful sensory stimulation of infants, especially the newborn and preterm ones, can produce equal or higher levels of physiological stress activation than painful stimulation. Repeated nociceptive stimulation probably sensitises the infants to pain.     

胎膜早破对新生儿健康危害的研究

目的 探讨胎膜早破(PROM)对新生儿健康的影响.方法 对我院3320例住院新生儿资料进行回顾性分析,其中PROM患儿711例.用系统抽样法随机选取各100例足月PROM及未足月PROM患儿,与正常新生儿进行对照分析.结果 25%(178/711)PROM患儿发生各种感染性疾病,其中肺炎与败血症占87.1%(155/178),主要为感染性肺炎(92/711,12.9%)和败血症(63/711,8.9%).血培养阳性率38.7%(63/163),主要致病菌为G+球菌(45.9%)和G-杆菌(54.1%);检出呼吸窘迫综合征69例,占9.7%(69/711);PROM的新生儿血小板计数减少,宽度变窄,血小板平均容积增加,P<0.01;多项红细胞参数值高于正常组(P<0.05);心肌酶谱明显异于正常组(P<0.05);PROM对新生儿的电解质水平无明显影响;PROM的足月儿及早产儿平均住院时间分别延长20.0%、25.1%(P<0.05);平均住院费用足月儿增加30.5%,早产儿则增加60.0%,P<0.05.结论 PROM可对新生儿健康造成多方面危害,应加强对PROM的研究,及时采取合理措施,减少对新生儿健康的危害.     

Anti-oxidant enzymes and related elements in term and preterm newborns

Background:  Although oxidative stress-related diseases mostly affect neonates with extremely low birthweight, healthy preterm newborns might also be at risk of oxidative damages. The aim of the present study was to verify this possibility.
Methods:  Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), erythrocyte glutathione peroxidase (GSHPx) and superoxide dismutase (SOD), plasma and erythrocyte concentrations of selenium, zinc and copper were measured until 100 days of life in 30 preterm infants with mean ± SD birthweight and gestational age of 1605 ± 122 g and 34.5 ± 0.5 weeks. The control group included 30 term infants with birthweight 3123 158 g and gestational age 39.6 0.7 weeks.
Results:  Throughout the study period urinary 8-OHdG, taken as a marker of oxidative stress, was significantly higher in the preterm than in the term group. Up until 20 days of life, GSHPx activity was significantly lower in the preterm than in the term infants but this was not associated with any apparent selenium deficiency. Conversely, up until 100 days, preterm infants had significantly reduced SOD levels that appeared to reflect a shortage of the elements needed for this enzyme's activity, notably copper, the plasma concentrations of which were constantly and significantly below the control values.
Conclusion:  The nutritional status of the elements related to the anti-oxidant enzymes, especially zinc and copper, should be carefully assessed in preterm infants, even if their birthweight is not extremely low.     

Free and sulfoconjugated plasma catecholamines in premature infants and mature newborn infants after birth

Sulfate conjugation represents a major pathway for the inactivation of free catecholamines. We investigated the ability of newborns to protect the body against an overflow of free catecholamines by sulfoconjugation. No difference of free catecholamines in the umbilical artery was found in preterm and term newborns. Furthermore, preterm and term newborns were able to form sulfoconjugated catecholamines. In term newborns, but not in preterm newborns, there was a significant relationship between free catecholamines and their respective sulfoconjugated forms (p less than 0.001). In comparison to term infants sulfoconjugated dopamine and norepinephrine were significantly decreased in preterm newborns, although the placental extraction rates of these catecholamines were markedly lower in preterm infants. This favors the conclusion, that synthesis rather than increased degradation may be responsible for the low levels of sulfoconjugated catecholamines in preterm infants. Thus, preterm newborns might be less able to inactivate free catecholamines by sulfoconjugation. The clinical importance of these results concerning treatment of preterm newborns with dopamine and noradrenaline has yet to be established.     

Can anesthesiologic strategies for caesarean section influence newborn jaundice? A retrospective and prospective study

RATIONALE AND OBJECTIVES: Neonatal jaundice is a frequent problem in neonatology and can be influenced by many factors. Our study arose from the clinical observation that among all newborns delivered by caesarean section in our center, some had a more intense physiological jaundice. We began by reviewing clinical anesthesiological case-sheets to ascertain whether this difference was linked to the use of different anesthesiologic strategies. We then performed a prospective study on healthy preterm and term newborns to verify this hypothesis. STUDY DESIGN: We retrospectively considered all healthy term newborns with weight > 2,400 g delivered by caesarean section from January 1998 to May 1999. In the prospective studies we included healthy term and preterm newborns consecutively delivered by caesarean section from May 1999 to December 1999. We excluded preterm newborns with gestational age < 31 weeks and with weight < 1,400 g. RESULTS: Both in retrospective and in prospective studies anesthetic agents employed were isoflurane (A), sevoflurane (B), or bupivacaine (C). The statistical comparison of the three groups in retrospective study confirmed the clinical observation: the total bilirubin levels were significantly higher in the isoflurane group than in the sevoflurane group (p = 0.0000) and bupivacaine group (p = 0.0002). Analysis of data from the prospective study on term newborns confirmed our previous results. In preterm infants total bilirubin is statistically higher in group A starting from 96 h postdelivery. CONCLUSIONS: It is likely that anesthetic technique can be included among factors with possible influence on neonatal jaundice.     

Serum pro-hepcidin levels and relationships with iron parameters in healthy preterm and term newborns

A recently isolated peptide hormone, hepcidin, is thought to be the principal regulator of iron homeostasis. Hepcidin acts by limiting intestinal iron absorption and promoting iron retention in reticuloendothelial cells. Its precursor peptide form is called pro-hepcidin. The aims of this study were to determine serum pro-hepcidin levels in healthy preterm and term newborns, and to assess possible relationships between pro-hepcidin and serum iron, serum ferritin, and transferrin. A serum sample was collected from each of 26 healthy preterm (gestational age < 37 weeks) and 16 healthy, full-term, appropriate-for-gestational age babies. The preterm babies were also divided into 2 subgroups based on gestational age. Samples were analyzed for complete blood count, serum iron and ferritin concentrations, iron-binding capacity, and transferrin and pro-hepcidin levels. Group findings were compared and correlations between pro-hepcidin and the iron parameters were tested. The respective serum pro-hepcidin levels (mean +/- SD) in the 16 healthy term and 26 healthy preterm newborns were 482 +/- 371.9 ng/mL and 496.7 +/- 443.5 ng/mL. Analysis revealed no significant correlations between serum pro-hepcidin level and serum iron, serum ferritin, or transferrin in the preterm or term newborns. Pro-hepcidin levels were not correlated with gestational age in the preterm group. The results indicate that healthy preterm and term newborns have high pro-hepcidin levels.     

Platelet aggregation in term and preterm newborns

The platelets of newborns have a hyporeactive period. This period, during which the platelet count is normal but their functions are deficient, is called transient platelet hyporeactivity of newborns. The platelet functions and their normalizing process of term and preterm neonates are investigated. Twenty term and 20 preterm (gestational age <37 weeks) newborns were enrolled in the study. Twenty-eight healthy children aged 2 months to 3 years old participated in the study as the control group. Healthy newborns were followed for 15 days after birth longitudinally in 3 periods: period 1 (0-4 days), period 2 (5-9 days), period 3 (10-15 days). Aggregation studies were performed from whole blood samples. Whole blood aggregation was measured by the impedance method. Transient hyporeactivity of platelets was found in term and preterm groups, and there was no difference between term and preterms. Platelets of newborns gained their normal functions at postnatal 10-14 days. The results show that hyporeactivity of platelets during the first 9 days of life is physiological and transient.     

PLATELET AGGREGATION IN TERM AND PRETERM NEWBORNS

The platelets of newborns have a hyporeactive period. This period, during which the platelet count is normal but their functions are deficient, is called transient platelet hyporeactivity of newborns. The platelet functions and their normalizing process of term and preterm neonates are investigated. Twenty term and 20 preterm (gestational age <37 weeks) newborns were enrolled in the study. Twenty-eight healthy children aged 2 months to 3 years old participated in the study as the control group. Healthy newborns were followed for 15 days after birth longitudinally in 3 periods: period 1 (0–4 days), period 2 (5–9 days), period 3 (10–15 days). Aggregation studies were performed from whole blood samples. Whole blood aggregation was measured by the impedance method. Transient hyporeactivity of platelets was found in term and preterm groups, and there was no difference between term and preterms. Platelets of newborns gained their normal functions at postnatal 10–14 days. The results show that hyporeactivity of platelets during the first 9 days of life is physiological and transient.