Plasma ionized magnesium levels in neonatal respiratory distress syndrome

Measurement of ionized magnesium (IMg) provides an accurate assessment of the free form of Mg, which is the physiologically active form and is most reflective of the biologically active and not easily measurable intracellular Mg fraction. Plasma levels of IMg were measured by ion-selective electrode method in premature newborns with respiratory distress syndrome (RDS), and relationships and correlations between IMg levels and various demographic, prognostic and laboratory characteristics were investigated by comparing the premature newborns with (study group; n = 19) and without RDS (control group; n = 20) in the present study. The values of the postnatal arterial pH and base excess and plasma IMg levels were significantly different between the study and control groups, and the number of newborns with any morbidity was significantly higher in the study group. Within the study group there were significant negative correlations between the plasma IMg levels and the values of the umbilical cord arterial pH (r = -0.621, p = 0.005) and base excess (r = -0.746, p = 0.001), and the value of the postnatal arterial base excess (r = -0.585, p = 0.008). The newborns who died later had higher plasma IMg levels than those who survived (0.89 +/- 0.45 vs. 0.63 +/- 0.24 mmol/l, p = 0.026). These findings suggest that increase of plasma IMg may be due to extracellular movement of Mg, which is a principally intracellular ion, as a result of acidosis, hypoxia and probable cellular injury during the early course of RDS. The exact pathophysiological mechanism responsible for IMg increase, and whether determination of plasma IMg level, including umbilical cord blood IMg measurement, can be used as an early or predictive indicator of RDS in the diagnosis remain to be determined in further large-scale studies.     

Ionized magnesium and gestational age

Objective Investigation of magnesium (Mg) homeostasis has re-emerged as an area of interest in preterm born neonates who are at risk for brain pathology. However, data regarding the association between the biologically active ionized form of Mg and gestational age (GA) at an early stage of life in newborn infants are controversial. Methods We evaluated the total and ionized Mg electrolyte (TMg and IMg) as well as the calcium (TCa and ICa) and pH in the cord blood and on day 2 of life in 22 neonates born at different gestational ages (<32, 32–34, and ≥35 week) without magnesium tocolysis and absence of serious complications during pregnancy and delivery. Results The IMg fraction that accounted for 68.1+/−5.1% of the TMg in the cord blood and 67.9+/−4.5% of the TMg on day 2 of life, was significantly higher in very preterm infants (GA<32 week) as compared to neonates with GA ≥35 week. Higher IMg levels were correlated with the lower pH that was recorded in the cord blood of the very preterm infants (correlation coefficient, r=−0.80, p<0.0001) and ICa (r = −0.52, P<0.01). Lower pH also was correlated with the GA (P<0.0001). However, standard multiple regression analysis showed significant association between IMg levels and decreased pH but not the gestational age or ICa (beta=−1.10+/−0.21, p<0.00009). Conclusion Extremely preterm infants even without additional exposure to tocolytic magnesium are at risk for the lower pH associated elevation of ionized Mg, which should be considered during the management of these infants in order to prevent hypermagnesemia-related pathology.     

Plasma methionine enkephalin levels in the human newborn at birth

Plasma met-enkephalin immunoreactivity (MET-ENKi) and catecholamine levels were measured in umbilibal cord blood from 46 healthy newborn infants. Clinical data including Apgar scores, birth weight, gestational age, route of delivery, fetal heart tracings and arterial blood gas values were also obtained. Thirty-nine infants were delivered by the vaginal route. All but 1 infant delivered by cesarian section had undergone a trial of labor. Plasma MET-ENKi in the newborn infants was markedly greater than levels found in healthy adult volunteers: 360 +/- 25 versus 25 +/- 2 pg/ml, respectively. MET-ENKi levels were similar in umbilical arterial and umbilical venous blood, and in infants delivered vaginally or by cesarian section.     

Plasma vasoactive intestinal polypeptide in the newborn infant

Vasoactive intestinal polypeptide (VIP) has been suggested as a possible contributor to the development of gastrointestinal problems. VIP is produced by nerve endings in the intestinal tract and appears to have marked effects on gut motility and its blood flow. Since necrotizing enterocolitis and feeding intolerance are common problems in the newborn, we examined the plasma VIP responses to feeding in healthy preterm and term newborn infants. Plasma VIP levels were measured in 20 full-term newborn infants (gestation of 39.4 +/- 0.9 weeks, mean +/- SD, and weight of 3,351 +/- 477 g) and 38 preterm infants (gestation of 27-35 weeks, weight of 920-2,440 g). In term infants, cord blood samples were obtained from the umbilical artery and vein and then before and after the feed. For preterm infants, blood samples were obtained prior to the introduction of oral feeds during the first week, and then before and after feeding once a week over the next 4 weeks. Feeding ranged from diluted premature formula to special care (24 calories per ounce) for the preterm, and breast milk or regular commercial formula for the term infants. Twenty-one healthy adults, age 25-42 years, were studied for comparison. In the term newborn infants, the plasma VIP levels in the umbilical venous blood were lower, although not statistically significant (p = 0.06), than the umbilical arterial blood (10.78 +/- 5.89 vs. 13.54 +/- 6.71 pmol/L), suggesting placental metabolism of VIP. After birth, there was a significant increase in plasma VIP levels (18.89 +/- 10.07 pmol/L, p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Serum total magnesium and ionized calcium concentrations in asphyxiated term newborn infants with hypoxic-ischaemic encephalopathy

Total magnesium, ionized calcium, potassium and sodium concentrations in mixed umbilical cord blood and venous blood serum at a median (min.-max.) age of 33 h (24-48 h) were assessed colorimetrically in 46 asphyxiated and 35 healthy term infants. Asphyxiated infants without any signs or with signs of mild hypoxic-ischaemic encephalopathy (HIE) had significantly higher, and infants with severe HIE lower umbilical cord blood serum total magnesium (mean (95%CI) 0.81 (0.75-0.87) mmol/l and 0.64 (0.47-0.87) mmol/l, respectively, p < 0.05) compared with the control group (0.72 (0.69-0.76)mmol/l). An increase in serum total magnesium in spite of normalized acid-base status in asphyxiated infants suffering from severe HIE compared with the control group infants was found by the second day of life (0.97 (0.87-1.07) mmol/l and 0.86 (0.81-0.9) mmol/l, respectively, p < 0.05). At the age of 24-48 h hypermagnesaemia (>2 SD) was discovered in 36%, hyponatremia (<2 SD) in 38%, and hypocalcaemia (<2 SD) in 23% of asphyxiated infants. Derangements (>2 SD) in at least two electrolytes by the second day of life were significantly associated with poor outcome. CONCLUSIONS: Magnesium, calcium and sodium derangements are a frequent finding in asphyxiated infants, and these abnormalities are significantly associated with poor outcome. For a better outcome prediction, the routine determination of magnesium in addition to other electrolytes in asphyxiated infants is recommended.     

Serum anion gap in the differential diagnosis of metabolic acidosis in critically ill newborns

OBJECTIVES: To determine in critically ill newborn infants (1) the range of the serum anion gap without metabolic acidosis and (2) whether the serum anion gap can be used to distinguish newborns with lactic acidosis from those with hyperchloremic metabolic acidosis. STUDY DESIGN: Umbilical arterial blood gases and serum electrolyte and lactate concentrations were measured simultaneously in 210 samples from 63 infants over the first week of life. Metabolic acidosis was defined as a blood base deficit (BD) >4 mmol/L. The anion gap was calculated as [Na(+)] - [C1(-)] - [TCO (2)]. Lactic acidosis was defined as a serum lactate concentration >2 SD above the mean serum lactate concentration in samples without metabolic acidosis. RESULTS: In 89 blood samples with BD <4 mmol/L, serum lactate concentration decreased with postnatal age (r = 0.51). The upper limit of serum lactate concentration was 3.8 mmol/L at less than 48 hours, 2.4 mmol/L between 48 and 96 hours, and 1.5 mmol/L for infants greater than 96 hours of age. The mean serum anion gap +/- 2 SD in 174 samples without lactic acidosis was 8 +/- 4 mmol/L; in 36 samples with lactic acidosis it was 16 +/- 9 mmol/L (P <.0001). Serum anion gap and lactate concentration were poorly correlated for samples without lactic acidosis (r = 0.04) but highly correlated in those with lactic acidosis (r = 0.81, P <.0001). None of the 85 samples with metabolic acidosis but without lactic acidosis had an anion gap >16 mmol/L; only 4 of 36 samples with lactic acidosis had an anion gap <8 meq/L. However, 25 of 36 samples with lactic acidosis had serum anion gaps of 8 to 16 mmol/L. CONCLUSION: In the presence of metabolic acidosis, a serum anion gap >16 mmol/L is highly predictive of lactic acidosis; a serum anion gap <8 is highly predictive of the absence of lactic acidosis; an anion gap = 8 - 16 mmol/L has no use in the differential diagnosis of metabolic acidosis in the critically ill newborn.     

The effects of acute and chronic perinatal stress on plasma vasopressin concentration and renin activity at birth

The effects of acute and chronic intrauterine stress on plasma vasopressin (AVP) concentration and renin activity (PRA) in the cord blood of 36 newborn infants were studied. AVP concentrations in the umbilical artery were significantly higher than those in the umbilical vein in all infants, except in those delivered by elective cesarean section after normal pregnancy. AVP concentrations in the umbilical arterial blood after normal term pregnancy and vaginal delivery (779 pg/ml, log mean) were higher than those in the cord blood of infants delivered vaginally after maternal hypertensive disease (198 pg/ml). Compared to the values of the latter group, the AVP values were significantly lower (39 pg/ml) in infants delivered by cesarean section without labor because of severe growth retardation and decreased heart rate variability. The group of normal term infants delivered by elective cesarean section after normal pregnancy had the lowest AVP concentrations (13 pg/ml). PRA in the umbilical arterial blood was not different from that in the umbilical venous blood. The highest mean level of PRA (14.5 ng/ml/h) was observed in premature infants delivered by cesarean section because of fetal growth retardation and pathological heart rate variability, and the lowest mean level in term infants delivered by elective cesarean section (3.4 ng/ml/h). PRA was significantly increased in term infants delivered vaginally after normal pregnancy (7.8 ng/ml/h) or after hypertensive pregnancy (11.7 ng/ml/h) in comparison to that of term infants delivered by elective cesarean section.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cord and placenta arterial gas analysis: the accuracy of delayed sampling

AIM: To determine the accuracy of delayed arterial gas sampling (1) from the umbilical cord and (2) from the placental surface at room temperature. METHODS: Term deliveries were classified a priori into three groups: normal vaginal deliveries, elective caesarean sections and high risk deliveries. The cord was double clamped and paired arterial samples were taken from the cord and the placenta at 0, 30, 60 and 90 min. RESULTS: 90 placentas were sampled with 30 cases per group. At time 0 the mean cord pH 7.207 (+/-0.08) was significantly lower than the placenta pH 7.240 (+/-0.08). The cord pH dropped significantly: by 0.050 (95% CI 0.036 to 0.063) at 30 min, 0.087 (95% CI 0.069 to 0.105) at 60 min, and 0.112 (95% CI 0.086 to 0.138) at 90 min. The placenta pH fell at twice the rate of the cord pH over 90 min. At time 0 the mean cord base excess -7.0 mmol/l (+/-4.1) was significantly lower than the placenta base excess -6.3 mmol/l (+/-3.6). The cord base excess fell at 30 min by 4.1 mmol/l (95% CI 3.4 to 4.7), at 60 min by 7.1 mmol/l (95% CI 6.1 to 8.0), and at 90 min by 9.0 mmol/l (95% CI 7.9 to 10.0). The pH and base excess rate of fall was similar for each of the three delivery groups despite differing starting values. CONCLUSION: Arterial blood gases should be taken as soon as possible after delivery from the umbilical cord. However, when this is not possible, the arterial pH and base excess from a delayed sample from a clamped cord at room temperature can be used to estimate the values at birth.     

新生儿脐血pH和BE影响因素的研究

目的通过大样本收集新生儿脐血血气,研究脐血血气统计学参考值范围与不同影响因素的相关关系。方法选择2012年5～11月广东省妇幼保健院和新会妇幼保健院产科出生的新生儿进行前瞻性研究,选取其中1rainApgar评分〉7分者的脐血血气结果进行统计分析,了解正常新生儿脐血血气的统计学参考值范围;重点分析影响新生儿脐血pH和BE的因素。结果2000例新生儿中,1min Apgar评分≤7分11例,〉7分1989例,低Apgar评分组pH〈7．2的比例为45．5％,正常Apgar评分组pH〈7．2的比例为3．5％,差异有统计学意义（P〈0．001）;1800例足月单胎、体重适于或大于胎龄新生儿中,1794例1min Apgar评分〉7分者脐血pH和BE的统计学参考值范围分别是7．34±0．14（X±1．96S）和-3．53±6．57（X±1．96s）。单因素分析显示,宫内窘迫组、妊娠期并发症组pH值均低于对照组,剖宫产组pH和BE值均高于阴道分娩组,脐带绕颈组pH值降低,双胎组BE值高于单胎组;羊水性状对pH、BE值均无影响。多因素分析显示,宫内窘迫、分娩方式均对脐血血气有影响。结论足月单胎、体重适于或大于胎龄新生儿中,1min Apgar评分〉7分者脐血pH值和BE值的统计学参考值范围分别是7．34±0．14和-3．53±6．57;Apgar评分与脐血血气分析具有一致性,但单独使用Apgar评分诊断早产儿窒息可能会增加窒息的误诊率;宫内窘迫可能会增加新生儿酸中毒的发生率,不同分娩方式对脐血血气pH、BE值均有影响。     

Amylin peptide levels are raised in infants of diabetic mothers.

BACKGROUND: Amylin is a novel 37 amino acid peptide hormone that is co-secreted with insulin from the pancreas in response to food intake. As a potent inhibitor of gastric emptying it plays an important role in the control of carbohydrate absorption. Feed intolerance is common in infants of diabetic mothers (IDM). AIMS: To establish a normal range of amylin levels in healthy neonates, and to determine whether serum amylin levels are raised in IDM. METHODS: A serial sample of 221 infants > or =28 weeks gestation was enrolled prior to delivery over a 12 month period. Blood samples collected immediately after birth (umbilical cord), and at the routine Guthrie test were analysed for amylin and insulin levels. RESULTS: Amylin levels in umbilical cord (n = 181) and Guthrie samples (n = 33) of healthy infants were 5.7 (3.0-9.1) and 6.9 (2.9-9.0) pmol/l respectively. IDM had significantly raised amylin levels in both cord (n = 31; 32.7 pmol/l, 25.9-48.1) and Guthrie samples (n = 8; 18.1 pmol/l, 15.3-23.6). Amylin correlated positively with insulin (n = 42; r = 0.67; 95% CI 0.4 to 0.81), birth weight (r = 0.22; 95% CI 0.08 to 0.36), and gestation (r = 0.18; 95% CI 0.03 to 0.32). Umbilical cord venous amylin levels showed agreement with arterial cord amylin levels (n = 34, mean bias -0.2, 95% CI 3.1 to -3.6). CONCLUSIONS: Amylin levels are significantly increased in the umbilical cord and Guthrie blood samples in IDM.     

Hypoxanthine as a measurement of hypoxia.

The hypoxanthine concentration in plasma was found to be a sensitive parameter of hypoxia of the fetus and the newborn infant. The plasma level of hypoxanthine in the umbilical cord in 29 newborn infants with normal delivery varied between 0 and 11.0 mumol/liter with a mean of 5.8 mumol/liter, SD 3.0 mumol/liter. Compared with this reference group the hypoxanthine concentration in plasma of the umbilical cord in 10 newborn infants with clinical signs of intrauterine hypoxia during labor was found to be significantly higher, with a range of 11.0-61.5 mumol/liter, with a mean of 25.0 mumol/liter, SD 18.0 mumol/liter. The plasma level of hypoxanthine in two premature babies developing an idiopathic respiratory distress syndrome was monitored. The metabolite was found to be considerably increased, in one of them more than 24 hr after a period of hypoxia necessitating artificial ventilation. The hypoxanthine level in plasma of umbilical arterial blood was followed about 2 hr postpartum in three newborn infants with clinical signs of intrauterine hypoxia. The decrease of the plasma concentration of the metabolite seemed to be with a constant velocity, as it was about 10 mumol/liter/hr in these cases. A new method was used for the determination of hypoxanthine in plasma, based on the principle that PO2 decreased when hypoxanthine is oxidized to uric acid.     

Concentrations of magnesium and ionized calcium in umbilical cord blood in distressed term newborn infants with hypoxic-ischemic encephalopathy

Magnesium and ionized calcium in mixed umbilical cord blood was assessed colorimetrically in 38 distressed and 21 healthy term newborn infants. Distressed infants with a severe or moderate degree of hypoxic-ischemic encephalopathy (HIE) ( n = 8) had significantly lower ( p < 0.001 (concentrations of magnesium (0.52 ± 0.08 mmol/L) compared to the control group (0.69 ± 0.06 mmol/L). No differences in concentrations of ionized calcium between distressed and control infants were detected.     

Congenital oral mucosal abnormalities in true umbilical cord knots

OBJECTIVE: The pathogenesis and clinical significance of true umbilical cord knots remain controversial. Here, we tested the hypothesis of the presence of congenital oral mucosal changes in newborns with true umbilical cord knots. STUDY DESIGN: Seven consecutive infants with true umbilical cord knots and 50 gestational age- and sex-matched controls were enrolled. The proportion of oral frenulum abnormalities and the two-dimensional vascular network geometry [fractal dimension, D, at two scales: D(1-46), and D(1-15), with the relative Lempel-Ziv complexity, (L-Z)], were analyzed. RESULTS: Infants with true umbilical cord knots showed significantly higher proportions of mandibular frenulum agenesis compared to controls (p = 0.000006). The oral vascular networks of these infants exhibited a significantly higher D(1-46) and D(1-15) (p < 0.0001, respectively), and higher L-Z values (p < 0.0001) than control networks. CONCLUSION: These findings indicate the presence of significant congenital oral mucosal changes in newborn infants with true umbilical cord knots, thus suggesting a previously unrecognized association between true umbilical cord knots and a subclinical extracellular matrix disorder.     

Intrapartum surveillance of IUGR fetuses with cardiotocography and fetal pulse oximetry

OBJECTIVE: To investigate the efficacy and safety of intrapartum fetal pulse oximetry, as a predictor of metabolic acidosis at birth of fetuses with intrauterine growth retardation (IUGR). STUDY DESIGN: We studied 18 IUGR fetuses (group I) and a control group of 30 appropriate for gestational age (AGA) fetuses (group II) during labor. Both groups had abnormal fetal heart rate tracings and were monitored simultaneously throughout labor with cardiotocography and fetal pulse oximetry. Apgar scores, pH and base excess of fetal blood obtained from the umbilical artery after delivery were compared in both groups. SETTING: The Fetal Surveillance Unit of the 2nd Department of Obstetrics and Gynecology, Aretaieion Hospital, Medical School, Athens University. RESULTS: In IUGR fetuses, when their oxygen saturation value (FSPO2) was less than 34%, cord artery pH was 7.10 +/- 0.04, base excess -13 +/- -1 mmol/l and Apgar scores < or =5 at the 5th min, and when FSPO2 was over 35%, artery pH was 7.29 +/- 0.08, base excess -8 +/- -2 mmol/l and Apgar scores > or =7 at the 5th minute. In cases of drops of FSPO2)below 30% for more than 2 min, labor was completed operatively and cord pH was 7.00 +/- 0.04, base excess -15 +/- -2 mmol/l and Apgar scores < or =5 at the 5th minute. In AGA fetuses, when FSPO2 was over 30%, artery pH was over 7.20, base excess <-11 mmol/l and Apgar scores > or =9 at the 5th minute; in contrast, when FSPO2 was <30% for 2 min, a cesarean section was performed and cord pH was < or =7.02, base excess > or =-13 mmol/l and Apgar scores < or =4 at the 5th minute. CONCLUSIONS: In IUGR fetuses, FSPO2 values less than 34% represent an acidotic status, while values of > or =35% are well tolerated. Fetal pulse oximetry proved reliable, according to umbilical cord blood measurements and Apgar scores, reducing cesarean deliveries in cases of nonreassuring cardiotocographic patterns in IUGR fetuses.     

Serum anion gap in the umbilical cord blood of healthy newborn infants

This paper presents the results of the determination of serum anion gap in arterial and venous umbilical cord blood obtained from a carefully selected group of 47 healthy term newborns. In the arterial blood, the following concentrations of particular anions were found: chloride - 102.85 +/- 4.35 mmol/l, bicarbonate - 22.26 +/- 2.67 mmol/l, protein anions - 11.89 +/- 1.00 mmol/l, and residual anions - 14.26 +/- 4.35 mmol/l, while in the venous blood these values were: chloride - 104.28 +/- 4.14 mmol/l, bicarbonate - 20.79 +/- 2.70 mmol/l, protein anions - 12.48 +/- 1.23 mmol/l, and residual anions - 13.03 +/- 3.06 mmol/l. Provided strict clinical and biochemical (acid-base balance and blood gases) selections criteria are applied, these data are likely to represent normal values for term newborns and can be the basis for comparison of umbilical serum anion gap in newborns under depressed conditions, like asphyxia. As discussed, the role of serum anion gap studies in the diagnosis of the type of metabolic acidosis, as well as in the monitoring of neonatal therapy is most important.     

Evaluation of umbilical cord pH and its relationship with Apgar score in term newborn infants

The value of the Apgar score as an index of birth asphyxia has been recently questioned. The purpose of the present study is to evaluate the relationship between cord blood pH and Apgar score in term newborn infants.A cross-sectional study involving 76 term newborn infants was performed from March through September 1995 at the Obstetric Unit of Hospital de Clínicas de Porto Alegre. The blood samples were obtained from umbilical cord artery and vein at the moment of delivery. Infants were divided in three different groups according to the Apgar score: Group A (n=60): >or=7 at one and five minutes; Group B (n=13): < 7 at one minute and >or=7 at five minutes; Group C (n=3): < 7 at one and five minutes. The frequency of acidemia in Group A was 18.3% (11 newborn infants) considering arterial pH < 7.20 and 5% considering arterial pH or= 7.20 and nine (56.2%) had arterial pH > 7.10. None of the newborn infants in Group C had arterial pH > 7.10. The sensitivity and specificity values for Apgar score less than 7 at one minute for detection of fetal acidemia were, respectively, 54.1% and 94.1%. This study confirms a poor correlation between Apgar score and umbilical blood cord pH, even in a term newborn, and emphasizes the importance of obtaining umbilical cord pH to consider the diagnosis of perinatal asphyxia.     

Plasminogen activators and plasminogen activator inhibitors in plasma of premature and term newborns

Objective : To compare the plasminogen activators (tPA, uPA) and their inhibitors (PAI-1, PAI-2) at different gestational ages, related to levels in women at term and non-pregnant women. Methods : Blood samples were obtained by puncture of the umbilical cord vein, in gestational weeks 39–40 ( n = 21), 30–32 ( n = 15), and 27–29 ( n = 9). Analyses of PA and PAI antigen concentrations and of PAI-1 activity were performed. Results : The mean tPA antigen level in term newborn infants was 14.5 μg/l compared to the premature newborns (7.0 μg/l) women at term (7.5 μg/l) and non-pregnant women (2.3 μg/l). PAI-1 activity and PAI-2 antigen concentrations were also higher in term newborn than in premature infants. Conclusions : The plasma levels of the plasminogen activators and inhibitors are higher in term newborn compared with premature newborn infants, reflecting maturation of protein synthesis.     

Natural killer cell activity and delivery: possible influence of cortisol and anesthetic agents. A study on newborn cord blood

The aim of this study was to evaluate the influence of the method of delivery, the level of cord blood lidocaine, and the cortisol concentration on the cord blood natural killer (NK) activity in the full-term healthy newborn. We studied healthy newborns delivered by elective cesarean section without labor under general anesthesia (n = 24), delivered by cesarean section under epidural anesthesia (n = 21), and delivered vaginally with uncomplicated labor (n = 19). The NK cell activity was significantly lower in newborns delivered by cesarean section under epidural anesthesia than it was in the general anesthesia group, while it was similar to the levels found in vaginally delivered newborns. The cortisol concentration was highest in the vaginal delivery group (589.2 +/- 200 mmol/l) and lowest in the general anesthesia group (199.2 +/- 81.9 mmol/l). The mean serum lidocaine concentration was 414.1 +/- 370 microgram/l in the epidural anesthesia group and undetectable in the other groups. In conclusion, our data suggest that the cord blood NK activity was significantly influenced by the method of delivery. This effect could be related to anesthetics given to the mother for general or epidural anesthesia or to the endocrine-metabolic variations observed after different degrees of delivery-related stress. The NK cells being a first-line defense mechanism against viral infections, the results of this study suggest an association with the occurrence of early perinatal infections, especially in preterm infants.     

Autologous umbilical cord blood transfusion.

The purpose of this study was to examine some aspects of umbilical cord blood collection for autologous transfusion in premature infants. All 120 microbacterial cultures (aerobic and anaerobic) of cord blood samples as well as 30 cultures of mycoplasma were treated. Cord prothrombin fragment (F 1 + 2) concentrations were quantified at one and 10 minutes after clamping of the cord. F 1 + 2 concentrations assessed on 25 newborn infants were similar and no linear association with time of clamping could be drawn. This means that cord blood thrombosis is not activated for at least 10 minutes following clamping of the cord. As far as is known, the first newborn infant to benefit from this method of transfusion is reported here. The premature infant received two portions of autologous blood (on days 5 and 7). No untoward effects were noted. Blood, collected from the umbilical cord, is a safe source for autotransfusion, provided that bacteriological testing has been carried out.     

High total and free 1,25-dihydroxyvitamin D concentrations in serum of premature infants

We investigated the relationship between serum total and free 1,25-dihydroxyvitamin D (1,25-OH2D) and the biochemical regulation of 1,25-OH2D production in premature infants. We measured 1,25-OH2D, vitamin D binding protein and related biochemical parameters and calculated the free 1,25-OH2D index in serum of 17 premature infants (birthweight 810-1700 g; gestational age 31-36 weeks) on two different occasions defined by body weight (Study A: 1,750-1,850 g, Study B: 2,100-2,200 g). Dietary calcium (Ca) intake was 1,5 or 2,6 mmol/kg/d, phosphorus (P) intake 1,7 mmol/kg/d and vitamin D intake 1,000 IU/d. Biochemical results were similar in infants with different Ca intakes and all were within reference ranges. Concentrations of vitamin D binding protein (Study A 0.15 +/- 0.03 g/l, Study B 0.14 +/- 0.03 g/l; means +/- SD) were lower, concentrations of 1,25 (OH)2D (Study A 180 +/- 67 pmol/l, Study B 216 +/- 53 pmol/l) were higher, and consequently the free 1,25-OH2D index (Study A 6.6 +/- 2.7, Study B 8.8 +/- 2.6) was 4 to 6 times higher than in previously studied term infants. 1,25-OH2D and the free 1,25-OH2D index increased significantly with age and were not correlated with serum P or parathyroid hormone. The data indicate that in premature infants with normal biochemical parameters of Ca and P metabolism elevated concentrations of 1,25-OH2D signify an increased fraction of free 1,25-OH2D and that increased production of 1,25-OH2D is not due to hypophosphatemia or hyperparathyroidism.