To clarify the role of the ventromedial hypothalamus (VMH)-sympathetic nervous system in insulin-independent glucose uptake in peripheral tissues, tissue glucose uptake was assessed in vivo by the 2-[3H]deoxyglucose method during electrical stimulation of the VMH in anesthetized rats. VMH stimulation significantly increased the rate constant of glucose uptake in brown adipose tissue (BAT), heart and skeletal muscles, but not in white adipose tissue and brain. The effect of VMH stimulation on glucose uptake in BAT was abolished by local sympathetic denervation, indicating that the increase in glucose uptake is mediated by the sympathetic nerves. Electrical stimulation of the lateral hypothalamus, on the other hand, had no appreciable effects on 2-[3H]deoxyglucose uptake in any tissues. Changes in glucose transporters after VMH stimulation were also examined by the [3H]cytochalasin B binding method using sarcolemmal membranes isolated from heart muscle. Scatchard analysis of cytochalasin B binding indicated that VMH stimulation did not alter both the number and affinity (dissociation constant) of glucose transporters in the heart sarcolemmal membranes, whereas insulin administration increased the number of transporters in the membranes. These results suggest that the mechanism by which VMH stimulation increases glucose uptake in muscle is different from that of insulin.

Animals↗

PubMedDate not supplied

Assessment of local cerebral blood flow in neonates with N-isopropyl-P-[123I]iodoamphetamine and single photon emission computed tomography.

Local cerebral blood flow was measured in 10 high-risk infants with neonatal episodic neurological events at 41-44 post-conceptional weeks using N-isopropyl-p-[123I]iodoamphetamine (IMP) and single photon emission computed tomography (SPECT). In 5 of the 7 infants with normal neurological outcome, prominent cerebral perfusion was found in the basal ganglia, brainstem, cerebellum, parietal white matter, and sensory motor cortex. The frontal lobes showed poor relative perfusion. In 3 infants with severe neurological deficits, SPECT demonstrated severe hypoperfusion of all parts of the brain except the basal ganglia, brainstem and sensorimotor cortex. However, MRI revealed non-specific changes, such as poor myelination and ventricular dilatation. SPECT, when performed in the first weeks of life, can be useful and may be more sensitive than MRI in predicting the occurrence of major neurological handicaps. However, because of the relatively invasive character and high cost of SPECT, SPECT should not necessarily be performed in all high-risk neonates.

Amphetamines↗

PubMedDate not supplied

Superior sagittal sinus thrombosis in neonates.

Three neonatal patients with superior sagittal sinus thrombosis are reported. The neurologic signs were bulging of the anterior fontanel and clonic hemi-convulsions. Neonatal polycythemia was believed to be an etiologic factor in two patients. Computed tomography revealed massive edema with slit-like ventricles in two patients. Increased density of the torcular Herophili and straight sinus also were demonstrated in two patients. The diagnosis of superior sagittal sinus thrombosis was confirmed by cerebral angiography in one patient and by digital subtraction angiography in the other two patients. Digital subtraction angiography appears to offer a definite advantage in the diagnosis of cerebral sinus thrombosis in the neonatal period.

Cerebral Angiography↗

PubMedDate not supplied

Septo-optic dysplasia with infantile spasms.

A 21-month-old boy with septo-optic dysplasia and infantile spasms is reported. Eighteen hours after birth he had generalized convulsions, dyspnea, and hypoglycemia which were followed by recurrent clonic seizures despite administration of phenobarbital and valproic acid. At 16 months of age he had hypoglycemia and apnea attacks during varicella infection. At 19 months of age left hemiconvulsions and left hemiparesis occurred; his mental and motor development, which had been delayed but progressive, deteriorated. Tonic spasms appeared at 21 months of age and electroencephalography revealed multifocal spikes. At 27 months of age electroencephalography disclosed hypsarrhythmia. Cranial computed tomography depicted brain atrophy, right microphthalmia, and intact septum pellucidum. Magnetic resonance imaging demonstrated hypoplasia of the corpus callosum and a small pituitary gland. Coloboma of the right optic disc was detected. Physical examination revealed short stature, left hemiparesis, micropenis, and cryptorchidism. Endocrinologic loading tests revealed hypofunction of the hypophysial anterior lobe.

Endocrine Glands↗

PubMedDate not supplied

Periventricular hyperintensity detected by magnetic resonance imaging in infancy.

Twenty-one infants younger than 12 months of age were diagnosed as having periventricular hyperintensity (PVH) on T2-weighted magnetic resonance imaging. Ten infants had experienced neonatal asphyxia, 6 intracranial hemorrhage, 2 bacterial meningitis, and 3 apnea. PVH was classified according to its extent. Round foci of PVH surrounding the frontal and occipital horns of the lateral ventricles were observed in 4 infants (PVH pattern I). Continuous PVH was observed in 17 infants (PVH patterns II and III). Fourteen infants with continuous PVH had spastic diplegia or quadriplegia. Developmental delay was demonstrated in 15 infants with continuous PVH. No PVH pattern I infants had cerebral palsy; only 1 such infant had mild developmental delay. Our study suggests that the extent of PVH reflects the severity of brain damage in neonates with cerebral injuries.

Asphyxia Neonatorum↗

PubMedDate not supplied

Auditory brainstem response in hyperbilirubinemic rats: Part II.

The effect of an albumin-bilirubin solution on the auditory brainstem response (ABR) of rats was examined and compared with that of rats in which only bilirubin was administered. In albumin-bilirubin-loaded rats, the latencies of waves II and IV were prolonged and the amplitudes decreased, whereas the ABR wave I did not change significantly. The I-IV interpeak latency also was prolonged. These changes were more severe in rats loaded only with bilirubin. Mannitol injection hastened the appearance of ABR changes when only bilirubin was used, but peak levels of ABR changes were almost the same in the mannitol-injected groups. When the blood-brain barrier is intact, albumin administration is useful in hyperbilirubinemia for the prevention of damage to the central auditory pathways. The reversibility of the ABR changes were demonstrated in all bilirubin-administered groups.

Animals↗

PubMedDate not supplied

Magnetic resonance imaging in preterm infants.

Magnetic resonance imaging was performed in 9 preterm infants at 37-43 weeks postmenstrual age. They all were born at 26-35 weeks gestation. Myelination was graded according to its most cephalic location. Myelination pattern 2 (myelination observed in the posterior limb of the internal capsule and adjacent structures of the thalamus and lenticular nucleus) was demonstrated in 2 infants, pattern 3 (myelination of the corona radiata) in 3 infants, and pattern 4 (myelination of the centrum semiovale) in 4 infants. Bilateral low intensity areas were found on T1-weighted images in 7 infants and a ribbon-like, high intensity was observed in 5. These findings revealed a wide variety of magnetic resonance imaging appearance in apparently normal preterm infants. Caution is needed in interpreting the pathologic nature of such features in preterm infants during the perinatal period.

Asphyxia Neonatorum↗