Biomedical subjects

Yoav Littner

Publications and source records attributed to Yoav Littner.

18 recordsLinked to original sources

PubMed2006

Detection of alcohol consumption during pregnancy--current and future biomarkers.

Alcohol, one of the most frequently reported addictions, is a significant public health problem in the USA. Early identification is important and would aid in intervention for the pregnant woman who continues to drink and for the affected infant. To date, there isn't a definitive test which identifies either alcohol abuse during pregnancy or newborns exposed to alcohol prenatally. The existing biomarkers can detect varying degrees of alcohol exposure but further research is needed to improve sensitivity/specificity and to validate these markers.

Alcohol Drinking↗

PubMed2006

Circadian variations in fat content of expressed breast milk from mothers of preterm infants.

BACKGROUND: Little is known about circadian variations of the fat content in expressed human milk by mothers of preterm infants. OBJECTIVE: To test the hypothesis that the fat content of expressed preterm human milk is higher in samples expressed in the evening (i.e. after 3 daily meals) than in the morning (after a night-long fast). METHODS: We collected samples of expressed human milk obtained from 39 mothers of hospitalized growing preterm infants aged 7-14 days, with a gestational age at birth ranging from 26 to 33 weeks, who routinely expressed all their milk every 3 hours, during the day time, just before bed time, and as soon as they woke up, using a commercial breast pump (Medela AG, Baar, Switzerland). One sample was obtained from the first morning expression (between 0600 and 0900) and the second from the evening expression (between 2100 and 2400). The entire quantity of expressed milk was collected, mixed and measured in a capillary tube after centrifugation at 9000 rpm for 5 minutes. Creamatocrits (CMT) were performed in duplicates. Each sample was read independently by 2 investigators who were not aware of the origin and time of sampling and the results were averaged. Results are expressed as mean +/- SD, and analyses were by paired t-test and regression analysis. RESULTS: CMT was significantly higher in evening than in morning samples (7.9 +/- 2.9% vs. 6.6 +/- 2.8%, P = 0.005). Neither CMT nor the morning-evening difference in CMT correlated with gestational age or birthweight. The morning CMT correlated significantly with the evening CMT (P < 0.001). CONCLUSIONS: There are significant circadian variations in the CMT of expressed preterm human milk. We speculate that if higher caloric content of expressed human milk is needed in a specific preterm infant, evening sample, if available, should be used preferentially.

Adult↗

PubMed2006

Conclusiveness of the Cochrane Neonatal Reviews: a systematic analysis.

AIM: To assess the conclusiveness of the Cochrane Neonatal Reviews (CNRs). We tested the hypotheses that: 1) the majority of the reviews is inconclusive; 2) the majority of reviews recognizes the need for further studies; 3) the ability to reach a conclusion is dependent upon both the number of studies and the number of patients. We also aimed to determine whether the conclusiveness of the CNRs was affected by time. METHODS: We selected CNRs available in the Cochrane Library in June 2004. The number of randomized clinical trials (RCTs) found, number of RCTs included for analysis, number of patients enrolled, the stated need for further studies, and the conclusiveness of CNRs were recorded. RESULTS: Out of 170 CNRs, 67.7% were conclusive. The average number of articles was similar, but the total number of patients enrolled was three times higher in the conclusive CNRs. The percentage of articles included in conclusive studies was significantly higher than in inconclusive ones. The vast majority of CNRs recognized the need for further studies. The number of studies included correlated significantly with the total number of patients included. The percentage of conclusive CNRs correlated negatively with year of publication. CONCLUSION: The majority of CNRs is conclusive, but emphasizes the need for further studies. The ability of a CNR to reach a conclusion is affected by the cumulative sample size and by the number of studies performed. The probability of a newer review to be conclusive is lower than that of an older review.

Humans↗

PubMed2006

Signaling pathways regulating cell motility: a role in ethanol teratogenicity?

This article summarizes the proceedings of a symposium presented at the 2005 annual meeting of the Research Society on Alcoholism in Santa Barbara, California. The organizer and chair was Tara A. Lindsley. The presentations were (1) Ethanol and Neuron Migration in the CNS, by Michael W. Miller; (2) Ethanol and L1-mediated Neurite Outgrowth, by Yoav Littner and Cynthia F. Bearer; and (3) Ethanol and Axon Guidance, by Tara A. Lindsley.

Abnormalities, Drug-Induced↗

PubMed2005

Negative results and impact factor: a lesson from neonatology.

OBJECTIVE: To test the hypothesis that articles with negative results are more likely than articles with positive results to be published in journals with lower impact factor. DESIGN AND SETTING: We selected all of the randomized, placebo-controlled trials conducted during the neonatal period between October 1, 1998, and October 1, 2003. Trials were classified as having positive results or negative results (significant or no significant difference, respectively). Only studies dealing with primary outcomes (efficacy) were included. MAIN OUTCOME MEASURES: The impact factor of each journal was determined, and the sample size for each study was noted. RESULTS: There were 233 articles that fulfilled the inclusion criteria. There was a significant difference between the 2 groups in terms of impact factor (P = .03) but not sample size (P = .30). Impact factor correlated with both sample size and the type of study results (positive results vs negative results; P<.05). CONCLUSION: Articles with negative results are more likely than articles with positive results to be published in journals with lower impact factor.

Bibliometrics↗

PubMed2005

Effect of hematocrit on exhaled carbon monoxide in healthy newborn infants.

OBJECTIVE: We tested the hypothesis that, the red blood cell (RBC) mass, estimated by hematocrit (HCT) or hemoglobin (Hb) level, influences the carbon monoxide (CO) production rate. STUDY DESIGN: The relationship between end tidal CO corrected for ambient carbon monoxide level (ETCOc) and the RBC mass have been studied in 58 full-term infants at the mean age 4.9 hours. RESULTS: Mean ETCOc was 1.88 ppm (1.3 to 3.4 ppm). ETCOc correlated significantly with HCT (R 2=10.1%, p=0.015) and with Hb (R 2=11%, p=0.011). Infants with a capillary HCT >65% had significantly higher ETCOc (mean 1.99+/-0.49 ppm) than infants with a capillary HCT <65% (1.74+/-0.39 ppm), p=0.035. When CO production was corrected for HCT (ETCOc/HCT), this difference did not longer exist. CONCLUSIONS: In newborn infants ETCOc significantly correlates with RBC mass. Comparing different infant's CO generation rate one should take into consideration their initial RBC level. In order to adjust for the existing differences in RBC, we suggest the use of the ETCOc/HCT index.

Breath Tests↗

PubMed2005

The effect of prolonged rupture of membranes on circulating neonatal nucleated red blood cells.

OBJECTIVES: To test the hypothesis that absolute nucleated red blood cells (ANRBC) counts are higher at birth in infants who were born after prolonged rupture of membranes (PROM, >24 hours). STUDY DESIGN: Retrospective study of 31 infants admitted to the neonatal intensive care unit who were born after PROM, and pair matched for gestational age and Apgar scores with 31 no PROM controls. Venous ANRBC counts were obtained within 1 hour of life. RESULTS: Groups did not differ in birthweight, gestational age, Apgar scores, and platelets counts. The ANRBC counts and hematocrit were significantly higher in infants who were born after PROM than in controls. CONCLUSIONS: Infants born after PROM have higher ANRBC counts at birth than control infants. We suggest that increased fetal erythropoiesis exists in infants who are delivered after PROM. If correct, our interpretation supports the theory that fetal hypoxia and/or ischemia may result from PROM.

Apgar Score↗

PubMed2005

Bone ultrasound velocity of infants born small for gestational age.

BACKGROUND: Quantitative ultrasound is increasingly used to assess bone status. Bone speed of sound (SOS), a biophysical property of bone, has been used to predict bone breakability. While decreased bone mineral content and delayed epiphyseal growth have been reported in small for gestational age (SGA) infants, there are no data on bone SOS in this group of infants. OBJECTIVE: To test the hypothesis that SGA infants have lower bone SOS than appropriate for gestational age (AGA) infants. METHODS: Bone SOS was measured within the first 96 hours of life at the right tibial midshaft in 22 singleton SGA infants. We compared these data with data obtained in 73 AGA controls. We used the Omnisense instrument which measures axially transmitted SOS. Infants ranged in gestational age (GA) from 25 to 42 weeks and in birth weight (BW) from 500 to 2,585 g. Statistical analyses included paired t-tests between the actual value obtained in every child and the theoretical, computed average normal value for GA, BW, or knee-sole length (KSL) based on our curves for AGA singletons. A p value < 0.05 was considered significant. RESULTS: Bone SOS measured in SGA infants was higher than the predicted computed average SOS of AGA singletons with significant differences in all of the parameters studied. CONCLUSIONS: Contrary to our hypothesis, SGA infants have higher bone SOS than AGA controls. Since bone mineral density is reported to be low in these infants, we speculate that intrauterine growth restriction may affect bone mineral density and bone protein matrix in opposite directions.

Bone Density↗

PubMed2004

Nucleated red blood cells in concordant, appropriate-for-gestational age twins.

OBJECTIVES: The purpose of this study was to test the hypothesis that neonatal nucleated red blood cell (RBC) counts are elevated in nondiscordant twins compared with singletons. STUDY DESIGN: We compared absolute nucleated RBC counts taken after birth in 2 groups of term, appropriate-for-gestational age infants; 74 concordant twins, and 29 singleton control infants. We excluded infants with factors associated with a potential increase in absolute nucleated RBC counts. RESULTS: Birth weight and gestational age were significantly lower in twins than in singletons (P < .01). Hematocrit, absolute nucleated RBC count, and corrected lymphocyte counts were significantly higher in twins (P < .01). In multiple regression, the significantly higher absolute nucleated RBC count in twins remained significantly higher even after taking into account gestational age and Apgar scores. CONCLUSION: Concordant, appropriate-for-gestational age twins have increased nucleated RBCs at birth compared with singleton control infants.

Apgar Score↗

PubMed2004

Nucleated red blood cells in preterm infants who have necrotizing enterocolitis.

Absolute nucleated red blood cell counts for 23 preterm newborn infants who subsequently had development of necrotizing enterocolitis were significantly higher than for 23 control infants. These infants may have been exposed to relative intrauterine hypoxemia, a possible risk factor for the development of necrotizing enterocolitis.

Case-Control Studies↗

PubMed2004

Decreased bone ultrasound velocity in large-for-gestational-age infants.

BACKGROUND: Bone speed of sound is a measure of bone breakability. There are few reports on bone mineral content in large for gestational age infants; most of them in infants of diabetic mothers. There are no data on bone speed of sound in large for gestational age infants of nondiabetic mothers. OBJECTIVE: To test the hypothesis that large for gestational age infants of nondiabetic mothers have lower bone speed of sound than appropriate for gestational age infants. DESIGN/METHODS: Bone speed of sound was measured within the first 96 hours of life at the right tibial midshaft in 25 singleton large for gestational age infants of non diabetic mothers and compared to appropriate for gestational age controls. RESULTS: Bone speed of sound measured in large for gestational age infants of nondiabetic mothers was lower than in controls. CONCLUSIONS: Large for gestational age infants of nondiabetic mothers have lower bone speed of sound than controls.

Birth Weight↗

PubMed2004

Bone ultrasound velocity of appropriately grown for gestational age concordant twins.

In neonates, quantitative ultrasound has been shown to be predictive of bone breakability and an index of biophysical property of bone. There are no data on bone speed of sound (SOS) in appropriate for gestational age (AGA) twins. The purpose of this study was to test the hypothesis that AGA twins who had normal intrauterine growth have bone SOS similar to that of AGA singletons. We measured tibial midshaft bone SOS within the first 96 hours of life in 25 pairs of AGA twins, 27 to 40 weeks gestation, and compared them with our data of 73 singletons. There were no significant differences in bone SOS between twin and singleton infants in any of the parameters studied. We found no significant difference in bone SOS between twins of the same pair. AGA twins have bone SOS very similar to that of AGA singletons. We suggest that intrauterine weight sparing occurs also in terms of biophysical properties of bone.

Bone Development↗

PubMed2004

Neonatal nucleated red blood cells in discordant twins.

The objective of this study was to test the hypothesis that in discordant twins, the smaller infant has higher absolute nucleated red blood cell (RBC) count than the larger sibling. We compared absolute nucleated RBC counts, hematocrits, absolute leukocyte counts, absolute granulocyte counts, absolute lymphocyte counts, RBC counts and platelet counts obtained in the first 12 hours of life in 30 discordant twin sets. The smaller infant had a higher absolute nucleated red blood cell count and lower platelet counts than its larger sibling. Platelet counts correlated inversely with absolute nucleated RBC counts ( R(2) = 24.5%; p < 0.001) and absolute nucleated RBCs correlated directly with percent intertwin weight differences ( R(2) = 17.8%; p = 0.02). In discordant twins, the smaller infant has higher absolute nucleated RBC count and lower platelet counts than the larger sibling. We speculate that the hematologic alterations in the smaller fetus are linked to relative fetal hypoxia.

Birth Weight↗

PubMed2004

Increased serum potassium and intraventricular hemorrhage revisited.

BACKGROUND: Increased serum potassium and intraventricular hemorrhage occur frequently in preterm infants. OBJECTIVE: To retrospectively analyze data obtained on infants with severe IVH in relation to blood K+ concentrations. METHODS: We identified all patients with severe IVH bom between July 1997 and July 2000. Each patient was pair-matched with a control infant of the same gestational age (+/- 1 week) without IVH in terms of head ultrasound findings on day 5 and whole blood K+ on days 3-5. RESULTS: There were 24 infants in each group. The IVH group had significantly lower 1 minute Apgar scores and pH and higher blood K+ than the control group. Blood pH and K+ were inversely correlated. Stepwise regression analysis, taking into account blood pH and 1 minute Apgar score, showed a correlation only between blood K+ and IVH status. CONCLUSIONS: Severe IVH is significantly associated with higher blood K+ concentrations. A causal relationship cannot be ascertained at this point.

Cerebral Hemorrhage↗

PubMed2004

Bone mass evaluation in children - comparison between methods.

Peak adult bone mass should be optimized during childhood and adolescence. The physiology of bone mass accretion during these early years of life has been extensively studied, due to the development of reliable, precise, little or noninvasive methods of bone mass assessment. The purpose of this review is briefly to describe quantitative aspects of bone mass accretion during intrauterine life, childhood and adolescence and to describe the methods that have been used to assess bone mass in children in terms of precision, accuracy, ease of use, invasiveness and normative data. In particular, we review major methods such as radiographic methods, photon absorptiometry, dual-energy X-ray absorptiometry, quantitative ultrasound, quantitative computerized tomography and other methods less frequently used.

Absorptiometry, Photon↗

PubMed2003

Nucleated red blood cells in polycythemic infants.

OBJECTIVE: This study was undertaken to evaluate whether the absolute nucleated red blood cell (RBC) count is elevated in term, appropriate-for-gestational-age (AGA) polycythemic infants. STUDY DESIGN: We compared absolute nucleated RBC counts taken during the first 12 hours of life in term, AGA infants with neonatal polycythemia (n = 29), and in control, nonpolycythemic infants (n = 37). We excluded infants of women with diabetes, hypertension, and alcohol, tobacco, or drug abuse, and those with fetal heart rate abnormalities or low Apgar scores, hemolysis, blood loss, or chromosomal anomalies. RESULTS: There were no differences between groups in birth weight, gestational age, or other demographic or perinatal factors. The hematocrit, RBC count, and absolute nucleated RBC counts were significantly higher and the platelet counts significantly lower in the polycythemic group. Regression analysis that included Apgar scores and gestational age showed a significant correlation of absolute nucleated RBC count with the polycythemia status only (P =.017). CONCLUSION: At birth, term AGA polycythemic infants have increased indices of active erythropoiesis. We speculate that this finding is suggestive of subtle fetal hypoxemia.

Apgar Score↗

PubMed2003

Nucleated red blood cells in infants of mothers with asthma.

OBJECTIVE: The purpose of this study was to evaluate whether the absolute nucleated red blood cell and lymphocyte count is elevated in term, appropriate-for-gestational-age infants born to women with asthma. STUDY DESIGN: We compared absolute nucleated red blood cell counts taken during the first 12 hours of life in two groups of term, vaginally delivered, appropriate-for-gestational-age infants; one group was born to mothers with active asthma during pregnancy (n = 28 infants), and the other group was born to control mothers (n = 29 infants). Asthma severity was classified according to the National Asthma Education and Prevention Program. We excluded infants of women with diabetes mellitus, hypertension, alcohol, and tobacco or drug abuse and infants with fetal heart rate abnormalities, hemolysis, blood loss, or chromosomal anomalies. RESULTS: There were no differences between groups in birth weight, gestational age, maternal age, gravidity, parity, maternal analgesia during labor, 1- and 5-minute Apgar scores, and infant sex. The hematocrit level, red blood cell count, absolute nucleated red blood cell count, and corrected leukocyte and lymphocyte counts were significantly higher in the asthma group than in the control group. The platelet count was not significantly different between groups. The absolute nucleated red blood cell count correlated significantly with the asthma severity score (r (2) = 28%, P <.001). Backward stepwise multiple regression that included Apgar scores and gestational age showed a significant correlation of absolute nucleated red blood cell count with the presence of asthma and its severity (P <.001). CONCLUSION: At birth, term appropriate-for-gestational-age infants born to mothers with asthma have increased circulating absolute nucleated red blood cell and lymphocyte counts compared with control infants.

Adult↗

PubMed2003

Bone ultrasound velocity curves of newly born term and preterm infants.

BACKGROUND: Ultrasound velocity (speed-of-sound [SOS]) has been proposed as a non-invasive method of evaluation of bone status in infants. We hypothesized that SOS correlates with both gestational age and birth weight. METHODS: We measured SOS within the first 96 hours of life at the right tibial midshaft location in 73 neonates ranging in gestational age from 25 to 41 weeks, and in birth weight from 825 to 3880 grams. We used the Sunlight Omnisense 7000p device (Tel Aviv, Israel). Results are expressed as meanS +/- 1 SD; statistical analyses included linear regression and computation of 95% CI regression lines; p<0.05 was considered significant. RESULTS: There was, as hypothesized, a significant correlation between gestational age (or birth weight) and SOS. There were no significant differences between males and females. Ninety-five percent confidence intervals were established. CONCLUSIONS: These data may be used as reference ranges for further studies.

Birth Weight↗