Pediatric research
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Case Reports
Human pulmonary acinar aplasia: reduction of transforming growth factor-beta ligands and receptors.
Pulmonary hypoplasia has been found in the human neonatal autopsy population and has been attributed to an alteration in epithelial-mesenchymal interactions during development of the lung. Pulmonary acinar aplasia is a very rare and severe form of pulmonary hypoplasia. The transforming growth factor-betas (TGF-beta) are multifunctional regulatory peptides that are secreted by a variety of normal and malignant cells and are expressed in developing organs including the lung; their tissue distribution patterns have possible significance for signaling roles in many epithelial-mesenchymal interactions. ⋯ Immunostaining for TGF-beta1, TGF-beta2, and TGF-beta RI and RII was significantly lower in the bronchial epithelium and muscle of the hypoplastic lungs than in normal lungs, whereas no difference was detected in staining for other proteins including Clara cell 10-kD protein, adrenomedullin, hepatocyte growth factor/scatter factor, and hepatocyte growth factor receptor/Met in the hypoplastic and normal lungs or in the liver and kidneys of this infant compared with normal liver and kidney. In addition, in situ hybridization showed that TGF-beta1 and TGF-beta RI transcripts were considerably reduced in the bronchial epithelium of the hypoplastic lung compared with normal lung. These results show that there is a selective reduction of TGF-beta in pulmonary acinar aplasia and suggest that the signaling action of TGF-beta in epithelial-mesenchymal interactions in the lungs of this developmental condition may be compromised.
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Cholestatic jaundice is the major complication of total parenteral nutrition (TPN) in infancy. We have previously shown that the TPN solution is directly toxic to the liver, and that this toxicity appears to be mediated by one or more amino acids. Elevated serum methionine levels, without corresponding increases in its metabolites, suggest that accumulation of this toxic amino acid may cause TPN cholestasis. ⋯ Despite full oral feeding, it produces a depression of bile flow and histologic liver injury similar to that seen with TPN. Elevated homocysteine levels suggests an enzymatic block early in the pathway of methionine metabolism. We believe that methionine may be an important factor in the pathogenesis of TPN cholestasis.
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Transcranial magnetic stimulation (TMS) has been used to describe cortical plasticity after unilateral cerebral lesions. The objective of this study was to find out whether cortical plasticity occurs after bilateral cerebral lesions. We investigated central motor reorganization for the arm and leg muscles in cerebral palsy (CP) patients with bilateral cerebral lesions using TMS. ⋯ In patients with spastic CP born prematurely, a significant lateral shift was found for the excitability sites for the tibialis anterior. No similar lateral shift was observed in the other CP patients. These findings suggest that ipsilateral motor pathways are reinforced in both spastic and athetoid CP patients, and that a lateral shift of the motor cortical area for the leg muscle may occur in spastic CP patients with preterm birth.
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The purpose of this study was to evaluate whether avoiding interruption of ventilation during surfactant instillation improves the effects on lung function and surfactant distribution and whether it prevents the adverse effects on blood pressure and cerebral blood flow. The study was performed using rabbits with severe respiratory failure induced by lung lavages. These rabbits were randomized to 99mTc-Nanocoll labeled surfactant instillation through a side lumen of the endotracheal tube without interrupting ventilation or instillation during a short interruption of ventilation. ⋯ Blood pressure increased quickly (16+/-4.2%), followed by a 40+/-10% decrease by surfactant instillation without interruption. Cerebral blood flow, measured by an ultrasonic transit time flow probe on the carotid artery, increased quickly (45+/-14%), followed by a 64+/-11% decrease with interruption, whereas it increased 15+/-4.9% (p = 0.06 versus with interruption) and decreased 61+/-13% without interruption of ventilation. Therefore, avoiding interruption of ventilation during surfactant instillation tends to prevent the potential adverse effects of a rapid rise in cerebral blood flow, and furthermore, tends to improve uniformity of surfactant distribution, whereas having no detrimental effect on respiratory function.
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We have previously reported concordant changes in cerebral intravascular oxygenation measured by near infrared spectroscopy (NIRS) and mean arterial blood pressure (MAP) in premature infants. We hypothesized that the cerebral oxygenation changes are caused by MAP-induced alterations in cerebral blood flow (CBF) and studied these parameters in neonatal piglets (n = 6). Changes in cerebral intravascular oxygenation were measured by NIRS from the hemoglobin difference (HbD) signal (oxyhemoglobin-deoxyhemoglobin). ⋯ HbD was significantly correlated with MAP (p < 0.05) and time average mean velocity (p = 0.01). Importantly, decreases in cerebral total hemoglobin (HbT), a measure of cerebral blood volume, did not correlate significantly with decreases in MAP. We conclude that 1) decreases in cerebral intravascular oxygenation, as assessed by NIRS, observed with decreases in MAP reflect a decline in CBF, and hence oxygen delivery, 2) the HbD signal is more sensitive to changes in CBF than the HbT signal, and 3) NIRS recordings may have clinical utility in detecting cerebral ischemia.