Biomedical subjects

J D Hanrahan

Publications and source records attributed to J D Hanrahan.

5 recordsLinked to original sources

PubMed1999

Relation between proton magnetic resonance spectroscopy within 18 hours of birth asphyxia and neurodevelopment at 1 year of age.

The aim of the study was to test the hypotheses that elevated cerebral lactate, detected by proton spectroscopy performed within 18 hours of suspected birth asphyxia, is associated with adverse outcome, and that increased lactate can be used to predict adverse outcome. Thirty-one term infants suspected of having had birth asphyxia and seven control infants underwent proton magnetic resonance spectroscopy, using three-dimensional chemical shift imaging, within 18 hours of birth. Adverse outcome was defined as death or neurodevelopmental impairment at 1 year of age or more. Nine infants had an adverse outcome. The other 22 and all of the control infants remained normal. Median (range) lactate/creatine plus phosphocreatine (lactate/creatine) ratios in the abnormal, the normal, and the control group were 1.14 (0.17 to 3.81), 0.33 (0 to 1.51), and 0.05 (0 to 0.6) respectively (P=0.003). Lactate/creatine >1.0 predicted neurodevelopmental impairment at 1 year of age with sensitivity of 66% and specificity of 95%, positive and negative predictive values of 86% and 88%, and a likelihood ratio of 13.2. Elevated cerebral lactate/creatine within 18 hours of birth asphyxia predicts adverse outcome.

Asphyxia Neonatorum↗

PubMed1998

Persistent increases in cerebral lactate concentration after birth asphyxia.

In this prospective study proton magnetic resonance spectroscopy (1H MRS) was used to test the hypothesis that lactate can be detected later than 1 mo after birth in the brains of infants who display severe neurodevelopmental impairment 1 y after transient perinatal hypoxia-ischemia. Data were obtained from three groups of infants: 1) eight infants suffering birth asphyxia followed by perinatal encephalopathy and abnormal neurodevelopmental outcome at 1 y of age (defined as major neurologic impairment, Griffiths quotient <85%, and low optimality score); 2) 10 infants with signs of perinatal hypoxia-ischemia but normal neurodevelopmental outcome at 1 y; and 3) six control infants with uneventful perinatal courses and normal neurodevelopment at 1 y. Between one and four examinations (median 1) were performed at median (range) 11 (4-68) wk after birth, and the cerebral concentration ratio of lactate to creatine plus phosphocreatine (Cr) calculated from each spectrum. Lactate was detected later than the 1st mo after birth in seven of eight infants with abnormal neurodevelopmental outcome [maximum detected lactate/Cr was median (range) 0.44 (0.24-0.67)]. No lactate was detected later than the 1st mo after birth in infants with normal neurodevelopmental outcome, nor in five of six control subjects, although a small amount of lactate was detected in one control infant (lactate/Cr=0.04). These results suggest that the pathologic postasphyxial process, indicated by persistent cerebral lactate, may not be confined to the period immediately after injury.

Asphyxia Neonatorum↗

PubMed1997

Noninvasive characterization of neonatal adipose tissue by 13C magnetic resonance spectroscopy.

In vivo 13C magnetic resonance spectroscopy (MRS) was applied noninvasively to analyze the fatty acid composition of adipose tissue in 21 full-term newborn infants and 6 mothers. In order to assess the effects of gestational and postnatal age on adipose tissue composition, we studied preterm infants at birth, term infants at the ages of 6 wk and at 6 mon. We also investigated the influence of maternal diet on infant adipose tissue composition by studying the breast-fed infants of women who maintained either an omnivore or a vegan diet. Significant differences were observed in adipose tissue composition of neonates compared with their mothers. Neonates had more saturated and less unsaturated fatty acids than their mothers (P < 0.01). We also observed changes in adipose tissue composition with maturity. From birth to 6 wk of age 13C MR spectra showed a significant increase in the amount of unsaturated fatty acids, particularly polyunsaturated fatty acids (P < 0.01). Similarly, differences were seen as a result of gestational age. Preterm infants had relatively fewer unsaturated fatty acids than full-term infants. A greater proportion of these unsaturated fatty acids were polyunsaturated. Our results demonstrate that 13C MRS can be utilized to assess noninvasively neonatal adipose tissue lipid composition and to monitor the effects of developmental changes due to gestational age and oral feeding.

Adipose Tissue↗

PubMed1996

Cerebral metabolism within 18 hours of birth asphyxia: a proton magnetic resonance spectroscopy study.

Proton magnetic resonance spectroscopy (1H MRS) was performed within 18 h of birth (median 13, range 4-18 h) on 16 term infants with clinical features of birth asphyxia. Ten infants with no evidence of birth asphyxia were studied as controls at 5-18 (median 8) h after birth. To detect delayed impairments in cerebral energy metabolism, 15 infants suspected of asphyxia underwent 31P MRS at 33-106 (median 62) h of age. Choline, creatine, and N-acetylaspartate (NAA) were detected in spectra located to the basal ganglia in all infants. Lactate was detected in 15 of the 16 infants suspected of asphyxia, but in only 4 of the 10 controls (p < 0.05, chi 2). Glutamine and glutamate (Glx) was detected in 11 infants suspected of asphyxia and in three controls, but this difference was not significant at the 5% level. The spectra revealed no other significant differences between asphyxiated infants and controls. In the asphyxiated infants, there was a negative correlation between the ratio of lactate to creatine in the first 18 h of life and phosphocreatine/inorganic phosphate (PCr/ P(i)) at 33-106 h (p < 0.001). Five severely asphyxiated infants had PCr/P(i) < 0.75 (median 0.53, range 0.14-0.65), indicating a poor neurodevelopmental prognosis, and a further infant died before PCr/Pi could be measured. Ten infants had PCr/P(i) > 0.75 (1.03, 0.76-1.49). Median lactate/creatine was 1.47 (range 0.67-3.81) in the six severely affected subjects, 0.38 (0-1.51) in the latter group, and 0 (0-0.6) in controls (p < 0.0005, Kruskall-Wallis). These results suggest that, after birth asphyxia, cerebral energy metabolism is abnormal during the period when 31P MRS characteristically gives normal results. 1H MRS might be of value in predicting which infants are likely to suffer a decline in cerebral high energy phosphate concentrations and subsequent neurodevelopmental impairment.

Asphyxia Neonatorum↗

PubMed1994

Early detection of cerebral infarction and hypoxic ischemic encephalopathy in neonates using diffusion-weighted magnetic resonance imaging.

Twelve newborn infants with clinical evidence of hypoxic ischemic brain injury had conventional and diffusion-weighted magnetic resonance imaging (MRI) performed one to six (median two) days and 7-42 days after birth. The extent and conspicuity of the early abnormalities was greater with diffusion-weighted than with conventional imaging in each of the four infants with neonatal infarction and in four of the infants with Grades II or III hypoxic ischemic encephalopathy (HIE). No abnormality was seen with either technique in the other four infants who had Grades I or II HIE. Diffusion weighted MRI may be important for the early diagnosis and grading of infants with hypoxic ischemic brain injury.

Asphyxia Neonatorum↗