The activity of phospholipase A2 from snake venom to hydrolyze bilayers of phosphatidylcholines is greatly enhanced by the presence of the hydrolysis products, lysolecithin and fatty acid, in the bilayer. The fluorescence of several probes of membrane structure was used to monitor changes in bilayer physical properties during vesicle hydrolysis. These changes were compared to emission spectra and fluorescence polarization results occurring upon direct addition of lysolecithin and/or fatty acid to the bilayer. The excimer to monomer ratio of 1,3-bis(1-pyrene)propane was insensitive to vesicle hydrolysis, suggesting that changes in the order of the phospholipid chains were not relevant to the effect of the hydrolysis products on phospholipase activity. The fluorescence of 6-propionyl-2-(dimethylamino)-naphthalene (Prodan) suggested that the polarity of the bilayer in the region of the phospholipid head groups increases as the hydrolysis products accumulate in the bilayer. The fluorescence of 6-dodecanoyl-2-(dimethylamino)naphthalene (Laurdan) confirmed that such effects were restricted to the bilayer surface. Furthermore, the lysolecithin appeared to be the product most responsible for these changes. These results suggested that lysolecithin increases the activity of phospholipase A2 during vesicle hydrolysis by disrupting the bilayer surface, making the phospholipid molecules more accessible to the enzyme active site.

BACKGROUND Neonates with necrotizing enterocolitis (NEC) have higher calprotectin levels in stool than do healthy neonates. However, it is not known whether high stool calprotectin at the onset of bowel symptoms identifies neonates who truly have NEC vs. other bowel disorders. STUDY DESIGN Neonates were eligible for this study when an x-ray was ordered to “rule-out NEC”. Stool calprotectin was quantified at that time and in a follow-up stool. Each episode was later categorized as NEC or not NEC. The location of calprotectin in the bowel was determined by immunohistochemistry. RESULTS Neonates with NEC had higher initial and follow-up stool calprotectin levels than did neonates without NEC. Calprotectin in bowel from neonates with NEC was within neutrophil extracellular traps (NETs). CONCLUSION At the onset of signs concerning for NEC, fecal calprotectin is likely to be higher in neonates with NEC. Calprotectin in their stools is exported from neutrophils via NETs.

OBJECTIVE Small-for-gestational-age (SGA) neonates, infants of diabetic mothers (IDM) and very-low-birth weight premature neonates (VLBW) are reported to have increased risk for developing iron deficiency and possibly associated neurocognitive delays. STUDY DESIGN We conducted a pilot study to assess iron status at birth in at-risk neonates by measuring iron parameters in umbilical cord blood from SGA, IDM, VLBW and comparison neonates. RESULTS Six of the 50 infants studied had biochemical evidence of iron deficiency at birth. Laboratory findings consistent with iron deficiency were found in one SGA, one IDM, three VLBW, and one comparison infant. None of the infants had evidence of iron deficiency anemia. CONCLUSIONS Evidence of biochemical iron deficiency at birth was found in 17% of screened neonates. Studies are needed to determine whether these infants are at risk for developing iron-limited erythropoiesis, iron deficiency anemia or iron-deficient neurocognitive delay.

Objective: Studies in adults indicate that ampicillin, in a dose-dependent manner, impairs platelet function and moderately prolongs the bleeding time (generally by 60 to 90 s). Unlike aspirin, the inhibition induced by ampicillin involves both reversible and irreversible mechanisms and is not observed immediately after initial dosing (generally requiring approximately 24 h). Ampicillin is administered commonly to neonatal intensive care unit (NICU) patients, but its effect on bleeding time in this population has not been reported earlier.Study Design: We performed neonatal template bleeding times and platelet function analyzer (PFA)-100 tests on 15 NICU patients before and at various intervals after intravenous ampicillin dosing.Result: Neonates were only studied if no beta-lactam antibiotics were administered to their mother during labor, and if they had ampicillin ordered by the clinician at a dose of 50 to 100 mg kg -1 every 12 h. Subjects ranged from 33 to 41 weeks gestation and weighed 1760 to 3835 g. Bleeding times before the first ampicillin dose (n ¼ 15) averaged 134 s (95% confidence interval (CI), 120 to 148 s) and PFA-100 times averaged 123 s (95% CI, 96 to 149 s). After the first dose of ampicillin (n ¼ 5), bleeding times and PFA-100 times did not increase, but after the third (n ¼ 5) and fourth doses (n ¼ 4) bleeding times lengthened by an average of 60 s (95% CI, 37 to 83 s, P<0.001) and PFA-100 times lengthened by an average of 20 s (95% CI, À20 to 60 s, P ¼ 0.15).Conclusion: Ampicillin administered intravenously to NICU patients prolongs the bleeding time, with a magnitude-of-effect and time-to-effect similar to that shown earlier in adults.

Using transfusion guidelines has been shown previously to reduce practice variability, lower transfusion rates and diminish transfusion costs. Based on our present findings, we maintain that even when transfusion guidelines are in place and adhered to rigorously, RBC transfusion rates are reduced further if anemia-preventing strategies are also in place.

Objective: Ibuprofen might have advantages over indomethacin, when used to effectuate closure of a neonate's patent ductus arteriosus (PDA). Several previous studies indicate that platelet plug formation is impaired after administration of indomethacin, but it is not clear whether a similar impairment occurs following ibuprofen dosing.Study Design: We performed template bleeding times and PFA-100 tests (platelet function analyzer) on 20 neonates who had a PDA, before and again at various preset intervals following ibuprofen dosing.Result: Patients ranged from 23 to 40 weeks gestation and weighed 511 to 2566 g. Their first dose of ibuprofen was administered at 72 h (18 to 363 h) after birth (median, range). None of the subjects had clinical bleeding problems noted during the days they received ibuprofen dosing. The template bleeding times before dosing ranged from 135 to 450 s. Repeat tests were performed in groups of four, at 2 h, 4 to 6 h, 12 to 18 h, 24 h after the first dose, and at 2 h after the third dose of ibuprofen. No changes in bleeding times were detected. (P ¼ 0.299) A PFA-100 time was performed on all 20 patients before and again after the ibuprofen administration. However, 3 of the 40 tests were unsuccessful, because of microclots in the blood sample (n ¼ 1) or failure of the analyzer for an unspecified reason (n ¼ 2). Before the dosing the PFA-100 time ranged from 52 to 300 s. A paired t-test showed a slight but statistically significant lengthening in PFA-100 time after the ibuprofen administration (P ¼ 0.019). The correlation between the bleeding time and the PFA-100 was poor (R 2 ¼ 0.212, P ¼ 0.576). Conclusion:On the basis of our present studies, we speculate that ibuprofen lysine administration to neonates with a PDA, when used according to the manufacturer's recommendations, has little adverse effect on platelet plug formation. This information might be a factor to consider when deciding whether to select indomethacin or ibuprofen for PDA closure.

Objective: On the day of birth, the bleeding time of very low birth-weight (VLBW, <1500 g) neonates is generally prolonged, compared with term neonates. However, their bleeding time generally improves (shortens) over the next 7 to 10 days. Ampicillin can prolong the bleeding times of term and late preterm neonates, but its effect on VLBW neonates, who already have a somewhat prolonged bleeding time initially, is not known.Syudy Design: This was a prospective, single-centered, paired, before vs after test of the effect of ampicillin on template bleeding time and PFA-100 time (platelet function analyzer). Ampicillin was dosed at every 12 h intravenously, but decisions about discontinuation were made by the responsible clinician, independent of this study.Result: A total of 20 VLBW neonates were studied. They ranged from 23-to 30-weeks gestation at birth and weighed 500 to1410 g. Initial bleeding times averaged 166 s (95% CI, 138 to 194) and initial PFA-100 times averaged 119 s (95% CI, 90 to 148). In all, 10 had ampicillin dosing stopped after a shorter course (4 to 7 doses) and 10 had it continued for a longer course (10 to 15 doses). Blood cultures were sterile in all 20, and no differences in laboratory or clinical features were found between those treated with a shorter vs longer course. After stopping the ampicillin following a short course the bleeding times and PFA-100 times were similar to the initial values. However, after a longer course the bleeding times were prolonged by an average of 2 min, to 284 s (95% CI, 242 to 326; P ¼ 0.001 vs initial). The PFA-100 times also trended longer by an average of 44 s (P ¼ 0.07). The number of doses of ampicillin received in the first week correlated with the degree of prolongation in bleeding time (r ¼ 0.68). Conclusion:Over the first week of life, a period when the bleeding time of VLBW neonates normally shortens, the opposite occurred (the bleeding time lengthened) if X10 doses of ampicillin were administered.

Objective: Platelet dysfunction has been described in adults during hypothermia. We sought to determine whether it also occurs in neonates. Methods: We measured bleeding times and PFA-100 (platelet function analyzer) times in 10 neonates with hypoxic-ischemic encephalopathy during and after head cooling. Results: The 10 neonates were born at 38.2 ± 1.6 weeks’ gestation (mean ± SD), with birth weights of 3,222 ± 746 g, pH 6.79 ± 0.17, base excess –25 ± 8, and 10-min Apgar 4 ± 2. Cooling was instituted 111 min (range: 66–180) after birth and continued 72 h. Bleeding times before cooling averaged 170 s (95% CI: 100–240). These lengthened during hypothermia, averaging 410 s (p = 0.000) and shortened after rewarming (p = 0.000). PFA-100 times were similar: prolongation during cooling and normalization after rewarming. Six neonates had clinical bleeding problems in the first 24 h of cooling, but were managed successfully, and no intracranial hemorrhages were identified. Conclusion: Defective platelet plug formation occurs during therapeutic hypothermia of neonates in a manner similar to that described in adults. Platelet impairment can be severe, but rapidly improves after rewarming.