The role of different X-inactivation pattern on the variable clinical phenotype with Rett syndrome.

A gene for Methyl-CpG binding protein 2 (MECP2), which locates Xq28, was recently found to be responsible for Rett syndrome. Although mutational analyses of MECP2 in Rett syndrome have been extensively analyzed, the mechanism(s) by which variable clinical phenotype occurred between affected monozygotic twins or sisters have not been clarified. We hypothesized that the difference of X-inactivation pattern might explain this phenomenon. With the method based on methylation-specific PCR, we analyzed polymorphic trinucleotide repeat in the human andorogen receptor gene mapped on Xq11.2-12, using DNA samples derived from previously described monozygotic twins and sisters together with their parents. Their clinical phenotypes were reported to be significantly different between siblings. We found that (1) maternally derived allele is predominantly active than paternally derived one in three out of four patients analyzed, (2) remaining one twin patient, whose ratio of active paternal allele is almost the same level as maternal allele, showed far much severe phenotype when compared with her counterpart. Together with the finding that most of the alleles with de novo mutation are from paternal X chromosome in sporadic cases, the existence of a mechanism that suppresses mutated paternal allele activation, resulting skewed X-inactivation to make clinical phenotype milder, might be speculated. Thus, when this mechanism fails to work sufficiently by an unknown reason, severer clinical phenotype could occur.

Engineering neoglycoproteins with multiple O-glycans using repetitive pentapeptide glycosylation units.

Controlled protein remodeling with O-linked glycans has been limited by our incomplete understanding of the process of glycosylation. Here we describe a secretable fibroblast growth factor (FGF) with multiple mucin-type O-glycans produced by introducing a minimum pentapeptide glycosylation unit in a decarepeat format at its N- or C-terminus. Expressed in Chinese hamster ovary cells, chemical and biochemical analyses of the resultant proteins (Nm10-FGF and Cm10-FGF, respectively) demonstrated that all O-glycosylation units were glycosylated and the dominant structure was sialylated Gal[beta1-3]GalNAc. This indicates that minimum O-glycosylation unit in multirepeat format serves as a remarkably efficient acceptor in CHO cells. The Nm10-FGF and Cm10-FGF proteins maintained the mitogenic activity to vascular endothelial cells. In addition, intact Cm10-FGF and its desialylated form interacted with several lectins in the same way as mucin-type glycoproteins. The intact Cm10-FGF with multiple sialylated O-glycans exhibited a longer lifetime in circulating blood, whereas the Cm10-FGF with desialylated O-glycans exhibited a shorter lifetime than the deglycosylated form of Cm10-FGF. Our approach would thus appear to be highly effective for engineering neoglycoproteins, the characteristics of which are determined by their multiple mucin-type O-glycans.

[Longitudinal study of cognitive function in two patients with focal cortical dysplasia].

To clarify the relationship between epileptic attacks and cognitive dysfunction, we examined the serial findings of 123I-IMP single photon emission computed tomography (SPECT) in relation to the intelligence quotient (IQ), assessed by Wechsler Intelligence Scale of Children-Revised, in two female patients with focal cortical dysplasia (FCD) over a 10-year period. The age of patient 1 at the initial assessment was 2 years, and the age of patient 2 was 9 months. They developed complex partial epilepsy in infancy, and were treated with antiepileptic drugs, which remained effective until 11 years of age, when their epileptic attacks recurred. Patient 1, a 14-year-old girl with FCD of the left parietal lobe suffered from dyscalculia, right-left disorientation, and finger agnosia even when she was free of epileptic attacks. Following the recurrence of seizures which occurred every night, she became unable to understand what was said to her. A hypoperfusion area detected by 123I-IMP SPECT was restricted to the left parietal lobe during the seizure-free period, but spread to the temporo-parietal lobes following the recurrence. Her verbal IQ declined from 94 (at 9 years of age) to 63 (at 11 years and 8 months). After her seizures were controlled again (at 14 years and 4 months), the 123I-IMP SPECT findings improved. Patient 2, a 12-year-old girl with FCD of the left frontal lobe, showed cognitive dysfunction. Her verbal IQ declined from 91 (at 7 years and 5 months) to 76 (at 11 years and 8 months) following a recurrence of epileptic attacks. 123I-IMP SPECT showed hypoperfusion in the left frontal lobe, where the accumulation count ratio (left/right ratio) declined from 0.86 (at 3 years) to 0.64 (at 11 years). These findings suggest that epileptic attacks are related to cognitive dysfunction in FCD patients. This cognitive dysfunction appears to correlate with the appearance of hypoperfusion areas, as detected by 123I-IMP SPECT.

Distinct regulation of myoblast differentiation by intracellular and extracellular fibroblast growth factor-1.

We studied the role of fibroblast growth factor (FGF)-1 in the physiology of myoblast differentiation. We found that, while endogenous FGF-1 in L6-10 rat myoblasts did not suppress the progress of differentiation, the addition of FGF-1 to the culture medium suppressed it. Moreover, L6-10 cells stably transfected with full length FGF-1 undergo enhanced differentiation. The latter was well correlated with myogenin expression and myotube formation. Constitutive expression of a mutant FGF-1 (FGF-1U) that lacked a nuclear localization signal, promoted the differentiation of the myoblasts even more strongly. Furthermore, the expression of FGF-1U in an inducible expression system enhanced myogenin expression promptly. In L6-10 transfectants expressing a dominant-negative mutant of FGF receptor, stable transfection of FGF-1 promoted differentiation as it did in parent cells. Studies with FGF receptors and MAP kinase suggest that both are involved in the effect of FGF-1 when it is supplemented to culture medium but not during the effect of endogenous FGF-1 synthesized in cells. We conclude that intracellular (endogenous) and extracellular (exogenous) FGF-1 have differential effects on the regulation of myogenic differentiation of L6-10 cells.

Development of spinal motoneurons in rats after a neonatal hypoxic insult.

To determine the developmental changes of cervical and lumbar motoneurons (MNs) during normal development and after a neonatal hypoxic insult, cervical and lumbar MNs were studied in rats of various postnatal ages using a retrograde neurotracing technique combined with immunohistochemistry. The results regarding normal development could be summarized as follows: (1) the dendrites elongated mainly during the first 5 postnatal days (PNDs), being longer and more extensive in cervical MNs than in lumbar MNs; (2) the average cell body area increased from PND 5 to 14; and (3) the distribution of cell body areas changed from a unimodal to a bimodal pattern between PND 5 and 14. The temporal differences in morphologic development between cervical and lumbar MNs may influence the motor development in a rostrocaudal manner. The dendrites of lumbar MNs were shorter and less extensive in rats with a neonatal hypoxic insult than in rats without one; no significant difference was observed in cervical MNs between the two groups. The developmental difference between cervical and lumbar MNs after a neonatal hypoxic insult may contribute to motor deficits, with greater effect on the lower than the upper limbs.

Cerebellar hypoperfusion and developmental dysphasia in a male.

A male with developmental dysphasia is documented with fine motor dysfunction whose improvement in expressive language was associated with increased cerebellar perfusion, as detected by serial N-isopropyl-p-[iodine-123] iodoamphetamine single photon emission computed tomography (SPECT). His expressive language has been improving since 6 years, 8 months of age, and his verbal intelligence quotient improved from less than 45 at 5 years of age to 80 at 8 years of age. Compared with the SPECT findings at 4 years of age, the ratio of the average pixel values of the cerebellum to the frontal cortices increased at 9 years of age (from 0.81 to 1.03-1.09 in the hemisphere and from 0.66 to 0.98 in the vermis). However, he was not able to understand stories presented orally even at 9 years, 4 months of age. These results suggest that developmental dysphasia, which mostly involves expressive impairment, in this patient could have been the result of delayed maturation of cerebellar function, mainly that of the vermis.

[A successful treatment with intravenous lidocaine followed by oral mexiletine in a patient with Lennox-Gastaut syndrome].

Clusters of atypical absence, myoclonic seizures and tonic seizures developed in a thirteen-year-old boy with Lennox-Gastaut syndrome. As conventional antiepileptic drugs failed to eliminate the seizures, we treated the patient with continuous intravenous lidocaine (4 mg/kg/hr). The treatment reduced the duration of paroxysmal discharges (spike-wave complexes and rapid rhythm) from 3 sec/min to 0.7 sec/min, monitored by EEG. Oral mexiletine (5.4 mg/kg/day) following the lidocaine treatment has maintained good seizure control for two years with no adverse effects, and improved his behavioral problem. The treatment with lidocaine followed by mexiletine was useful for controlling clusters of intractable seizures.

Beta-2-microglobulin and ferritin in cerebrospinal fluid for evaluation of patients with meningitis of different etiologies.

To determine whether or not the beta-2-microglobulin (beta2-m) and/or ferritin levels in cerebrospinal fluid (CSF) can be used as markers for the differential diagnosis of meningitis and determination of the response to treatment, 122 subjects with etiologically well-characterized diagnoses were classified into three groups: bacterial meningitis (n = 5; mean age +/- SD. 1.0+/-1.0 year), viral meningitis (n = 39; 5.9+/-3.8 years), and a non-meningitis group (n = 78; 5.2+/-4.9 years). The levels of beta2-m and ferritin in CSF were determined by means of a latex photometric immunoassay. The statistical significance of the data was analyzed with the Mann Whitney U-test. A receiver operating characteristic curve was used to evaluate the diagnostic accuracy of each prediction marker. This study indicated that (1) the levels of beta2-m and ferritin in CSF were related with age in the non-meningitis group: subjects of up to 5 months of age exhibited higher concentrations of these proteins than ones of above 6 months of age (beta2-m, 1.89+/-1.13 vs. 0.84+/-0.65 mg/l. P < 0.01; ferritin, 2.97+/-2.04 vs. 1.81+/-1.34 microg/l, P = 0.09); (2) the beta2-m level was significantly higher in the CSF of patients with viral meningitis than in ones without meningitis (2.41+/-1.23 vs. 0.84+/-0.65 mg/l, P < 0.01): the best cut-off value was 1.2 mg/l (3) the ferritin level was significantly higher in the CSF of patients with bacterial meningitis than in ones with viral meningitis (43.24+/-39.49 vs. 6.81+/-7.41 microg/l, P < (.01): the best cut-off value was 7.5 microg/l; and (4) sequential measurement of the CSF ferritin level was of value for determination of the response to antibiotic treatment for bacterial meningitis. These results only apply to patients of greater than 6 months of age. beta2-m and ferritin in the CSF can be used as an ancillary tool for diagnostic guidance in the acute phase of meningitis and determination of the response to treatment for bacterial meningitis.

Proton magnetic resonance spectroscopy to study the metabolic changes in the brain of a patient with Leigh syndrome.

Localized proton magnetic resonance spectroscopy (MRS) was performed to study the metabolic changes in the brain of a patient with Leigh syndrome, who had a T-->G point mutation at nt 8993 of mitochondrial DNA. In this patient, sodium dichloroacetate therapy normalized the lactate and pyruvate levels in both blood and cerebrospinal fluid (CSF). However, his psychomotor retardation did not improve and magnetic resonance imaging showed progressive cerebral atrophy. In the patient's spectra, elevation of brain lactate was observed throughout the brain with regional variations, predominantly in the basal ganglia and brainstem with an abnormal MRI appearance. Although the lactate/creatine ratio observed on proton-MRS was related to the CSF lactate level, the ratio did not completely parallel the CSF lactate level, i.e. brain lactate was detected even when the CSF lactate level had become normalized. Furthermore, proton-MRS revealed a decrease in the N-acetylaspartate/creatine ratio and an increase in the choline/creatine ratio, representing neuronal loss and breakdown of membrane phospholipids. The clinical and MRI findings were well related to the changes in spectroscopically determined brain metabolites. These results indicate that the brain metabolites observed on proton-MRS are useful indicators of a response to therapy and prognosis in Leigh syndrome.

Serum melatonin kinetics and long-term melatonin treatment for sleep disorders in Rett syndrome.

We studied the circadian rhythm of serum melatonin levels in two patients with classical Rett syndrome having severe sleep disorders; serum melatonin levels were measured before and during melatonin treatment using radioimmunoassay. Patient 1 had a free-running rhythm of sleep-wake cycle from 3 years of age. At the age of 4 years, the peak time of melatonin was delayed 6 h compared to normal control and the peak value was at the lower limit. Patient 2 had a fragmented sleep pattern accompanied by night screaming from 1 year and 6 months of age. At the age of 10 years, the peak time of melatonin secretion was normal but the peak value was at the lower limit. These patients were given 5 mg melatonin orally prior to bedtime. Exogenous melatonin dramatically improved the sleep-wake cycle in patient 1. In patient 2, exogenous melatonin showed a hypnotic effect but early morning awakenings occurred occasionally. When melatonin treatment was stopped, the sleep disorders recurred and re-administration of 3 mg melatonin was effective in both patients. The effect was maintained over 2 years without any adverse effects. These findings suggests that sleep disorders in patients with Rett syndrome may relate with an impaired secretion of melatonin.

Encephalopathy associated with haemophagocytic lymphohistiocytosis following rotavirus infection.

UNLABELLED: A 2-year-old Japanese boy with a haemophagocytic lymphohistiocytosis (HLH) associated encephalopathy which developed after rotavirus infection is described. The neurological symptoms consisted of coma, seizures and spastic quadriplegia. On therapy with steroids, etoposide and cyclosporin A, the patient recovered without any neurological deficits. The interferon-gamma levels in serum and CSF were elevated at onset of the disease but had returned to normal at the time of clinical remission. Brain MRI revealed diffuse white matter abnormalities and parenchymal volume loss. Proton magnetic resonance spectroscopy revealed elevated lactate in the abnormal lesions observed on MRI, indicating that macrophages not exhibiting aerobic metabolism had infiltrated the CNS. At the time of clinical remission, the white matter abnormalities and brain lactate had disappeared. These findings suggested that the neurological symptoms resulted from the overproduction of cytokines by activated T-cells and macrophages. The pathophysiology of a HLH associated encephalopathy was considered to be a local immune response within the CNS, because interferon-gamma can induce the expression of major histocompatibility complex class I and II antigens on glial cells in the CNS. CONCLUSION: Haemophagocytic lymphohistiocytosis associated encephalopathy should be considered early in the differential diagnosis of cases with acute onset neuropathy.

Cognitive deterioration associated with focal cortical dysplasia.

Surgery for an area of focal cortical dysplasia in a critical region is reported in a right-handed female manifesting intractable focal epilepsy and verbal cognitive deterioration. She developed the first seizure at 2 years of age and was treated with phenytoin and zonisamide, with good control until 10 years of age. Although seizures did not occur at 9 years of age, she manifested dyscalculia, right-left disorientation, and finger agnosia, and N-isopropyl-p-iodoamphetamine single-photon emission computed tomography (SPECT) revealed focal hypoperfusion in the left parietal lobe. At 11 years of age, she developed regular nocturnal seizures and gradually lost the ability to understand the meaning of sentences. Verbal IQ declined from 94 to 63, and the area of hypoperfusion detected by interictal N-isopropyl-p-iodoamphetamine SPECT spread over the left parietotemporal lobes. Magnetic resonance imaging revealed focal cortical dysplasia mainly in the left parietal lobe, and ictal technetium-99m-ethyl cysteinate dimer SPECT images demonstrated an area of hyperperfusion around the focal cortical dysplasia, including the left precentral gyrus. Because of the overlap between the epileptogenic and functional cortex, the authors concluded that cortical resection, including focal cortical dysplasia, was inappropriate in this patient.

Blood-brain barrier glucose transporter: effects of hypo- and hyperglycemia revisited.

The transport of glucose across the blood-brain barrier (BBB) is mediated by the high molecular mass (55-kDa) isoform of the GLUT1 glucose transporter protein. In this study we have utilized the tritiated, impermeant photolabel 2-N-[4-(1 -azi-2,2,2-trifluoroethyl)[2-3H]propyl]-1,3-bis(D-mannose-4-ylo xy)-2-propylamine to develop a technique to specifically measure the concentration of GLUT1 glucose transporters on the luminal surface of the endothelial cells of the BBB. We have combined this methodology with measurements of BBB glucose transport and immunoblot analysis of isolated brain microvessels for labeled luminal GLUT1 and total GLUT1 to reevaluate the effects of chronic hypoglycemia and diabetic hyperglycemia on transendothelial glucose transport in the rat. Hypoglycemia was induced with continuous-release insulin pellets (6 U/day) for a 12- to 14-day duration; diabetes was induced by streptozotocin (65 mg/kg i.p.) for a 14- to 21-day duration. Hypoglycemia resulted in 25-45% increases in regional BBB permeability-surface area (PA) values for D-[14C]glucose uptake, when measured at identical glucose concentration using the in situ brain perfusion technique. Similarly, there was a 23+/-4% increase in total GLUT1/mg of microvessel protein and a 52+/-13% increase in luminal GLUT1 in hypoglycemic animals, suggesting that both increased GLUT1 synthesis and a redistribution to favor luminal transporters account for the enhanced uptake. A corresponding (twofold) increase in cortical GLUT1 mRNA was observed by in situ hybridization. In contrast, no significant changes were observed in regional brain glucose uptake PA, total microvessel 55-kDa GLUT1, or luminal GLUT1 concentrations in hyperglycemic rats. There was, however, a 30-40% increase in total cortical GLUT1 mRNA expression, with a 96% increase in the microvessels. Neither condition altered the levels of GLUT3 mRNA or protein expression. These results show that hypoglycemia, but not hyperglycemia, alters glucose transport activity at the BBB and that these changes in transport activity result from both an overall increase in total BBB GLUT1 and an increased transporter concentration at the luminal surface.

Effects of neonatal hypoxia on the medulla-spinal cord descending neurons.

Hypoxic changes in the medulla-spinal cord descending neurons were studied morphologically using a retrograde neurotracer, choleratoxin B subunit (CTb). On postnatal day 7, Sprague-Dawley rats were subjected to a hypoxic load of 8% oxygen for 5 hours. In the rats that survived, CTb was injected into the lumbar enlargement at postnatal day 26, and they were killed at postnatal day 28 for histologic analysis. Retrograde transported CTb was visualized by immunohistochemistry. The results were compared with those obtained from control rats. In the control rats, CTb-positive cells were observed in the nucleus reticularis gigantocellularis, nucleus reticularis magnocellularis, nucleus raphe magnus, nucleus raphe obscurus, and nucleus raphe pallidus. In the hypoxic rats, although CTb-positive cells were detected in the same areas as the control rats, there was a noteworthy decrease in the number of CTb-positive cells in all areas, and there were many cells with hypoxic degeneration. In all of the nuclei a marked decrease in the number of CTb-positive cells was observed. Because medulla-spinal cord descending neurons have important roles in the regulation of postural muscle tone, these results may account for the pathophysiology of abnormal muscle tonus accompanying hypoxic brain damage.