Natural and hybrid immunity after SARS-CoV-2 infection in children and adolescents

PURPOSE

In contrast to adults, immune protection against SARS-CoV-2 in children and adolescents with natural or hybrid immunity is still poorly understood. The aim of this study was to analyze different immune compartments in different age groups and whether humoral immune reactions correlate with a cellular immune response.

METHODS

72 children and adolescents with a preceding SARS-CoV-2 infection were recruited. 37 were vaccinated with an RNA vaccine (BNT162b2). Humoral immunity was analyzed 3-26 months (median 10 months) after infection by measuring Spike protein (S), nucleocapsid (NCP), and neutralizing antibodies (nAB). Cellular immunity was analyzed using a SARS-CoV-2-specific interferon-γ release assay (IGRA).

RESULTS

All children and adolescents had S antibodies; titers were higher in those with hybrid immunity (14,900 BAU/ml vs. 2118 BAU/ml). NCP antibodies were detectable in > 90%. Neutralizing antibodies (nAB) were more frequently detected (90%) with higher titers (1914 RLU) in adolescents with hybrid immunity than in children with natural immunity (62.5%, 476 RLU). Children with natural immunity were less likely to have reactive IGRAs (43.8%) than adolescents with hybrid immunity (85%). The amount of interferon-γ released by T cells was comparable in natural and hybrid immunity.

CONCLUSION

Spike antibodies are the most reliable markers to monitor an immune reaction against SARS-CoV-2. High antibody titers of spike antibodies and nAB correlated with cellular immunity, a phenomenon found only in adolescents with hybrid immunity. Hybrid immunity is associated with markedly higher antibody titers and a higher probability of a cellular immune response than a natural immunity.

Nutritional Management in Children and Adolescents with Severe Neurological Impairment-Who Cares? A Web-Based Survey Among Pediatric Specialists in Germany

BACKGROUND

Nutritional management of children and adolescents with severe neurological impairment (SNI) is challenging. A web-based survey was distributed to identify the present situation and the knowledge of the involved medical professionals in Germany.

METHODS

The survey was created with LimeSurvey, and access data were distributed by several medical societies. Eighty-three questions covered four topics: "general information," "gastro- and jejunostomy procedure," "handling of gastrostomies and feeding tubes," and "nutritional management and follow-up of children and adolescents with SNI." A descriptive analysis was performed with Microsoft Excel.

RESULTS

A total of 156 participated (65 completed and 91 partially), 27% being pediatric gastroenterologists, 23% pediatric neurologists, and 10% pediatric surgeons. The most common indications for gastrostomy and tube feeding were oropharyngeal dysfunction and failure to thrive. Many patients were still underweight after some months of enteral feeding. The procedure of gastrostomy and handling recommendations varied broadly. Frequently, standard operating procedures (SOPs) and written local guidelines did not exist, and there was a considerable request for training. Only 53% of participants were aware of the European Society for Paediatric Gastroenterology, Hepatology and Nutrition position paper published in 2017, even fewer (38%) followed the guidelines. The recommended measures to assess a nutritional status were often not respected.

CONCLUSION

Nutritional management of children and adolescents with SNI in Germany is still strongly deficient. Despite the international guideline of 2017, few colleagues are aware of and adhere to the recommendations. This could be improved by interdisciplinary teaching and evaluation of the reasons for noncompliance. The procedure of gastrostomy and the patients' follow-up vary widely. Therefore, modified SOPs should be developed.

[The challenges of managing thoracic pain in cystic fibrosis (CF)]

BACKGROUND

Cystic fibrosis (CF) is a rare genetic multisystemic disorder with progressive abdominal and pulmonary involvement. Pain is still an underestimated symptom in CF patients.

METHODS

A comprehensive review of guidelines and scientific literature on the topic was performed and combined with findings from pain management in a young CF patient with progressive thoracic pain.

RESULTS

German CF guidelines do not cover diagnosis and management of pain in these patients. Studies from Europe and the United States report interactions between intensity of pain and mortality in CF, but do not include data on the efficacy of pain management. These data and clinical observations of a CF patient with episodes of intense thoracic pain are used to illustrate the specific challenges in pain relief.

CONCLUSION

Pain management in CF requires meticulous monitoring as well as an interdisciplinary approach and should be implemented in the German CF guidelines. The authors also want to suggest recommendations for the treatment of thoracic pain in CF. The range and severity of organ involvement complicates the use both of opioids and non-opioids. Especially opioid treatment carries the risk of hypoxia and opioid-induced constipation (OIC) and needs close medical supervision.

The Multiple Sclerosis Inventory of Cognition for Adolescents (MUSICADO): A brief screening instrument to assess cognitive dysfunction, fatigue and loss of health-related quality of life in pediatric-onset multiple sclerosis

OBJECTIVE

Screening for cognitive impairment (CI), fatigue and also Health-related quality of life (HRQoL) in patients with pediatric-onset multiple sclerosis (POMS) is of utmost importance in clinical practice. The aim of this study was to establish a new and validated pediatric screening tool "MUSICADO" that is easy to use and time economical.

METHODS

106 patients with POMS aged 12-18 years and 210 healthy controls (HCs) stratified for age and education underwent neuropsychological testing including a screening test "Multiple Sclerosis Inventory of Cognition" for adults and 8 standardized cognitive tests and established scales to assess fatigue and HRQoL.

RESULTS

The phonemic verbal fluency task (RWT "s-words"), the Trail Making Test A (TMT-A), and the Digit Span Forward discriminated significantly between patients and HCs (p = 0.000, respectively) and showed the highest proportion of test failure in patients (24.5%, 17.9%; 15.1%, respectively). Therefore, they were put together to form the cognitive part of the "MUSICADO". After applying a scoring algorithm with balanced weighting of the subtests and age and education correction and a cut-off score for impairment, 35.8% of patients were categorized to be cognitively impaired (specificity: 88.6%). Fatigue was detected in 37.1% of the patients (specificity: 94.0%) and loss of HRQoL in 41.8% (specificity 95.7%) with the screening version, respectively.

CONCLUSION

The MUSICADO is a newly designed brief and easy to use screening test to help to early identify CI, fatigue, and loss of HRQoL in patients with POMS as cut scores are provided for all three items. Further studies will have to show its usability in independent samples of patients with POMS.

Zur Neurologie bei der immuno-ossären Dysplasie Schimke (IODS)

Die klinische Trias der immuno-ossären Dysplasie Schimke (IODS) besteht aus spondyloepiphysärer Dysplasie, Nephropathie und Immunopathie. Neurologische Symptome sind bei >50% der Patienten mit IODS nachweisbar. Beschrieben wurden Kopfschmerzen, Doppelbilder, motorische Aphasien, Hemiparästhesien und Hemiparesen, die auf transitorische ischämische Attacken oder Hirninfarkte auf der Basis einer frühen generalisierten Arteriosklerose zurückgeführt werden. Trotz erfolgreicher Nierentransplantation kann es zu neurologischen Symptomen kommen; das transplantierte Organ bleibt von pathologischen Veränderungen verschont. Das Auftreten neurologischer Symptome scheint mit der Schwere der Erkrankung zu korrelieren. Eine Phänotyp-Genotyp-Korrelation besteht insofern, als klinisch schwerer betroffene IODS-Patienten auf beiden Allelen nonsense-, frame-shift-oder splicing-Mutationen des SMARCAL1-Gens aufweisen, wohingegen Patienten mit milden Verläufen missense-Mutationen auf jedem Allel zeigen. Eine wirksame Therapie der IODS und auch der neurologischen Symptome existiert bislang nicht. Die zugrundeliegende Pathologie der Erkrankung bleibt trotz bekanntem Gendefekt unklar.

[Current Practice of Pre- and Postnatal Screening and Future Developments for Evidence Based Guidelines]

Objectives: In this selective review we provide an overview of the current pre- and postnatal screenings up to 18 years established in Germany to inform physicians of different medical fields (gynecologists, pediatricians, general practitioners, other medical specialists who treat children, adolescents or pregnant females). Current State: Research on screening for different types of cancer has frequently failed to show any benefit. Thus, there is a need to broaden the evidence basis related to medical screenings especially for children and adolescents. Outlook: Potential future developments of pre- and postnatal screenings are illustrated including their social impact. The lack of an early detection of mental health problems is pointed out. An interdisciplinary collaboration and research is required to accumulate evidence with regard to medical screenings and to consider health economic and ethical aspects.

[Cognitive Development in Children with Benign Rolandic Epilepsy of Childhood with Centrotemporal Spikes - Results of a Current Systematic Database Search]

Benign Rolandic Epilepsy (BRE) is one of the most common epilepsy syndromes in childhood. Although global intellectual performance is typically normal in BRE-patients, problems were found in specific cognitive domains. To summarize recent empirical findings concerning cognitive development in children with BRE a systematic literature search of clinical studies published between 2009 and 2015 was performed. 19 studies of relevance were found.In most recent studies children with BRE consistently showed general intellectual performance within the normal range. However, in two of the studies patients showed a significantly poorer (but still normal) performance in comparison to controls. The studies provide clear indications for a high prevalence of impairments in language (10 out of 12 studies) and academic performance (6 out of 8 studies) in children with BRE. Regarding deficits in other cognitive domains (attention, memory, visual/auditory perception, executive functions) current findings are inconsistent. In addition, no clear results are found in studies examining cognitive development after remission of BRE. Studies on the relationship between selected clinical/electroencephalographic characteristics (e. g. EEG-patterns, focus lateralization) and cognitive performance and studies on potential benefits of anti-epileptic therapy for cognitive functions also have not yielded consistent results. Studies using fMRI and evoked potentials provide evidence for functional reorganization of neural networks in BRE.Due to the developmental risks in children with BRE early cognitive assessment, early treatment and follow-up assessments are important.

Dietary habits and metabolic control in adolescents and young adults with phenylketonuria: self-imposed protein restriction may be harmful

BACKGROUND

In untreated patients, phenylketonuria (PKU) results in severe encephalopathy with mental retardation. A protein-restricted diet is recommended which can be relaxed in adolescence/adulthood.

METHODS

We contacted all 72 adult/adolescent PKU patients who had been treated in our center during early childhood. Some still regularly attended our outpatient clinics, while others were lost for follow-up, giving 51 patients in our study. We asked all patients to complete a dietary protocol as well as a questionnaire on quality of life. Blood and urine were analyzed and body impedance plethysmography and cerebral MRI were performed.

RESULTS

42 % of the patients followed protein restriction supplemented with amino acid mixtures (AAM), others had a vegan diet with (8 %) or without (14 %) AAM; 36 % said they were eating normally and did not need any AAM. However, based on dietary protocols and blood urea levels, protein intake was restricted in this patient group. None of the patients examined had serious nutritional deficits. Phenylalanine levels were higher in patients not taking AAM. MRI of the brain was not different from those following protein restriction and taking AAM. The lesions score and mood correlated best with the cumulative phenylalanine values during the first 10 years of life.

CONCLUSION

In summary, 50 % of adult/adolescent patients from our center did not take AAM at the start of our survey although they unknowingly followed self-imposed protein restriction. They had no overt nutritional deficits; however, long-term brain function may be compromised. Our study emphasizes the need for specialized metabolic care in PKU during adulthood.

Dental abnormalities in Schimke immuno-osseous dysplasia

Described for the first time in 1971, Schimke immuno-osseous dysplasia (SIOD) is an autosomal-recessive multisystem disorder that is caused by bi-allelic mutations of SMARCAL1, which encodes a DNA annealing helicase. To define better the dental anomalies of SIOD, we reviewed the records from SIOD patients with identified bi-allelic SMARCAL1 mutations, and we found that 66.0% had microdontia, hypodontia, or malformed deciduous and permanent molars. Immunohistochemical analyses showed expression of SMARCAL1 in all developing teeth, raising the possibility that the malformations are cell-autonomous consequences of SMARCAL1 deficiency. We also found that stimulation of cultured skin fibroblasts from SIOD patients with the tooth morphogens WNT3A, BMP4, and TGFβ1 identified altered transcriptional responses, raising the hypothesis that the dental malformations arise in part from altered responses to developmental morphogens. To the best of our knowledge, this is the first systematic study of the dental anomalies associated with SIOD.

Molecular characterization of folate receptor 1 mutations delineates cerebral folate transport deficiency

Cerebral folate transport deficiency is an inherited brain-specific folate transport defect that is caused by mutations in the folate receptor 1 gene coding for folate receptor alpha (FRα). This genetic defect gives rise to a progressive neurological disorder with late infantile onset. We screened 72 children with low 5-methyltetrahydrofolate concentrations in the cerebrospinal fluid and neurological symptoms that developed after infancy. We identified nucleotide alterations in the folate receptor 1 gene in 10 individuals who shared developmental regression, ataxia, profound cerebral hypomyelination and cerebellar atrophy. We found four novel pathogenic alleles, one splice mutation and three missense mutations. Heterologous expression of the missense mutations, including previously described mutants, revealed minor decrease in protein expression but loss of cell surface localization, mistargeting to intracellular compartments and thus absence of cellular binding of folic acid. These results explain the functional loss of folate receptor alpha for all detected folate receptor 1 mutations. Three individuals presenting a milder clinical phenotype revealed very similar biochemical and brain imaging data but partially shared pathogenic alleles with more severely affected patients. Thus, our studies suggest that different clinical severities do not necessarily correlate with residual function of folate receptor alpha mutants and indicate that additional factors contribute to the clinical phenotype in cerebral folate transport deficiency.

Recurrent upper motor neuron facial weakness of possible epileptic etiology: a case report

We report on an otherwise healthy infant who presented with clusters of alternating central facial nerve paresis. At 11 months of age, the patient showed intermittent facial asymmetry compatible with right-sided upper motor neuron facial paresis and accompanying incomplete upper motor neuron hypoglossal paresis. Laboratory work-up and imaging studies did not reveal signs of infection, infarction or structural lesions, and after one week, symptoms spontaneously resolved. Similar episodes affecting alternate sides were noted at ages of 17, 27 and 49 months lasting for 4-14 days. At 49 months, EEG showed right temporo-occipital benign sharp waves with activation during drowsiness and sleep. A diagnosis of benign focal epilepsy with negative motor phenomena was made. She is now 60 months old and no further episodes have occurred without antiepileptic treatment. Ictal orofacial phenomena are the clinical hallmark of benign focal epilepsy with centro-temporal sharp waves (BECTS). As in our patient, negative epileptic motor phenomena frequently lead to a broad diagnostic work-up. In infants presenting with episodic central facial nerve paresis, the possibility of negative epileptic motor phenomena should be considered.

['Cases against KiSS': a diagnostic algorithm for children with torticollis]

In 1991, Biedermann coined the term "kinetic imbalance due to suboccipital strain" ("KiSS-syndrome"). He assumed a functional abnormality of the suboccipital-high cervical spine, resulting in positional preference of the infant;s head. A broad spectrum of symptoms and complaints have been attributed to "KiSS-Syndrome". Patients are advised to undergo manual therapy, with pressure applied locally in order to readjust the cervical spine. Life threatening side-effects have been published repeatedly. We present two infants with brain tumours who developed torticollis and further neurological findings such as ataxia and reflex differences. In both cases, symptoms caused by the tumour were interpreted as "KiSS-syndrome", and appropriate diagnostics and therapy were delayed for months. There is no scientific evidence for the actual existence of "KiSS-syndrome" as a clinical entity or for the positive effects of manual therapy. Approximately 12% of all infants <12 months show a positional preference of the head, about 8% present with body asymmetry. Whereas most cases are benign, there is a long list of serious differential diagnoses for torticollis in infants. We give an updated review of the literature regarding "KiSS-Syndrome" and discuss the differential diagnostics in infants with torticollis.

Scheie syndrome: enzyme replacement therapy does not prevent progression of cervical myelopathy due to spinal cord compression

Hurler-Scheie syndrome is caused by alpha-l-iduronidase deficiency. Enzyme replacement therapy (ERT) can improve physical capacity and reduces organomegaly. However, the effect on bradytrophic connective tissue is limited. As intravenously administered enzyme cannot cross the blood-brain barrier, the therapy of choice for the more severe Hurler syndrome is haematopoietic stem cell transplantation (HCT). In the more attenuated Scheie syndrome, neurological impairment is less severe; therefore, ERT may be appropriate to treat these patients. Information on long-term outcome in Scheie patients undergoing ERT is scarce. We report a 38-year-old female Scheie patient who has been on ERT for 8 years. While non-neurological symptoms improved, she developed paresthesias in her hands and feet and progressive pain in her legs. Somatosensory evoked potentials were abnormal, suggesting dysfunction of the dorsal funiculus and lemniscus medialis. After 6 years of ERT, a spinal MRI showed dural thickening at the upper cervical spine. These soft-tissue deposits are presumably due to the accumulation of mucopolysaccharides. Intramedullary hyperintensities at the level of C1/2 revealed cervical myelopathy. An MRI before the start of ERT had shown milder spinal lesions. Cystic lesions in the white matter of the centrum semiovale due to dilated Virchow-Robin spaces were essentially unchanged compared with the MRI scan before ERT. Decompression of the spinal cord resulted in clinical improvement. In an adult patient with Scheie syndrome, ERT failed to prevent progression of cervical myelopathy. Clinical significance of cerebral changes is unclear. Whether early HCT or intrathecal ERT could have prevented these lesions remains speculative.

Prenatal benzoate treatment in urea cycle defects

OBJECTIVE

In patients with severe urea cycle defects (UCD) metabolic decompensation with hyperammonaemia typically occurs during the first days of life resulting in severe neurological damage or death. Benzoate can eliminate nitrogen independent of the urea cycle. Usually, benzoate is started soon after birth, but prenatal administration might improve metabolic stability.

DESIGN

Two fetuses with a prenatal diagnosis of UCD (female: citrullinaemia; male: ornithine transcarbamylase deficiency) were loaded with benzoate prenatally via the placenta by infusing their mothers with benzoate. Benzoate concentrations were measured in umbilical cord blood and the blood of the mothers and their newborns.

RESULTS

Therapeutic concentrations of benzoate were found in umbilical cord blood and in the children's blood. Thus, benzoate transfer across the placenta was demonstrated. Plasma ammonia and glutamine levels in the postnatal period were within the normal range.

CONCLUSIONS

Benzoate infusion of the mother shortly before birth is safe and results in therapeutic levels of benzoate in umbilical cord blood.

Developmental changes of oxalate excretion in enterally fed preterm infants

To further substantiate gestational age-related changes in oxalate excretion, we studied urinary oxalate excretion in 66 preterm infants born at 23.4-34.7 weeks of gestation. Spot urine of 66 preterm infants was analysed by ion chromatography as soon as they were completely orally fed with enriched breast milk and/or special preterm milk formula (days 7 to 57 of postnatal life). Infants with evidence of renal, gastrointestinal, muscular or metabolic disease were not included. Newborns on parenteral nutrition were excluded. Oxalate/creatinine ratios (Ox/Cr) decreased with gestational age (three age groups: group 1, 23 0/7-28 0/7; group 2, 28 1/7-32 0/7; and group 3, 32 1/7-35 0/7 weeks of gestation). The mean Ox/Cr was highest in group 1 (398.2 mmol/mol +/- 116.8; n = 21). Differences between groups 1 + 3 were statistically significant; p = 0.001; those between groups 1 + 2 and between groups 2 + 3 were not. Ox/Cr correlated inversely with gestational and maturational age (r = -0.41, p = 0.001; r = -0.33, p = 0.007) and positively with postnatal age (r = 0.32, p = 0.008). It correlated inversely with birth weight as well as actual weight at sample collection (r = -0.46 and -0.44, p < 0.001). Ox/Cr was significantly linked to energy and carbohydrate intake (r = 0.3 and 0.4, p = 0.03 and 0.001). These results were independent of sex. In the present study we show that urinary oxalate excretion in preterm infants depends on gestational age.

[Maternal vitamin B12 deficiency: cause for neurological symptoms in infancy]

BACKGROUND

Symptoms of Vitamin B (12) deficiency in infancy include growth retardation, regression of psychomotor development, muscular hypotonia and brain atrophy. Besides an inappropriate vegetarian diet of the infants, a vegan diet or a pernicious anaemia of the mother may lead to an insufficient vitamin B (12) supply of the child.

PATIENTS AND METHODS

We report here the neurological symptoms of 4 fully breast-fed infants from mothers on vegan diet or with pernicious anaemia.

DISCUSSION AND CONCLUSION

Vitamin B (12) deficiency can easily be diagnosed by detection of methylmalonic acid when measuring the organic acids in urine. Vitamin B (12) deficiency should be avoided or diagnosed as early as possible since a supplementation of mother and child can prevent neurological symptoms of the baby. Furthermore, the neurological symptoms of the infant with manifest vitamin B (12) deficiency are (partially) reversible.

Novel mutations in exon 6 of the GFAP gene affect a highly conserved if motif in the rod domain 2B and are associated with early onset infantile Alexander disease

Alexander disease is a rare disorder of cerebral white matter due to a dysfunction of astrocytes. The most common infantile form presents as a megalencephalic leukodystrophy. Mutations of the GFAP gene, encoding Glial Fibrillary Acidic Protein, have been recognized as the cause of Alexander disease. Glial Fibrillary Acidic Protein is the major intermediate filament protein in astrocytes, its functional rod domain is conserved in sequence and structure among other intermediate filament proteins. We report here two cases of infantile Alexander disease with early onset and severe course, caused by DE NOVO mutations A364 V and Y366C. Both affected GFAP residues are part of a highly conserved coiled-coil trigger motif in the C-terminal end of segment 2B, probably required for the stability of intermediate filament molecules. Comparable effects are seen with mutations of the corresponding residues of the gene coding for keratin 14, another intermediate filament, this further supports the hypothesis that these positions of the trigger motif are generally critical for a normal function of intermediate filaments.

Vaso-occlusion in Schimke-immuno-osseous dysplasia: is the NO pathway involved?

Schimke-immuno-osseous dysplasia (SIOD) is an autosomal recessive disorder with the main clinical findings of spondyloepiphyseal dysplasia, nephrotic syndrome, and defective cellular immunity. Vaso-occlusive processes, especially generalized atherosclerosis, are a life-limiting complication in patients with severe SIOD. The nitric oxide synthase (NOS) oxidizes L-arginine to nitric oxide (NO). NO is a potent vasodilator with inhibitory effects on platelet aggregation and the development of atherosclerosis. We hypothesized that reduced NO production due to antagonism of NOS by asymmetric dimethylarginine (ADMA) would be a possible pathophysiological mechanism for vaso-occlusion in SIOD. We tested this hypothesis in 10 patients with SIOD and 10 age-matched healthy controls. Plasma and urine levels of nitrite and nitrate, the indicators of NO synthesis, and of ADMA, an endogenous NOS inhibitor, in children suffering from SIOD were not significantly different from those in the age-matched healthy controls. Our results suggest that the L-arginine/NO pathway is not altered in SIOD. Antagonism of NOS by ADMA does not seem to be the cause of premature general atherosclerosis in SIOD. The underlying pathology of vaso-occlusion in SIOD still remains unclear.

Branched chain amino acids as a parameter for catabolism in treated phenylketonuria

This study was performed to study an association between nutritional status on one hand and BCAA- and Phe-concentrations on the other hand in PKU patients free of infection. AA profiles from 70 PKU patients were measured. 9 patients (subgroup I) with elevated Phe- and BCAA-concentrations as well as 23 patients (subgroup II) with only elevated Phe-levels were included. Dietary records were obtained from both groups; low caloric intake in subgroup I was increased with Duocal or p-am ANAMIX without modifying total protein- and Phe-intake. AA profiles were controlled after 2 weeks. Additionally, we investigated AA profiles from 26 liver transplanted patients with increased carbohydrate and caloric intake as an example for anabolism. In subgroup I Phe- and Isoleu-concentrations decreased sign. After dietary intervention. Leu, Val and Tyr levels decreased not sign. Initial Phe-levels correlated negatively with protein and caloric intake. BCAA concentrations of liver transplanted patients receiving high amounts of carbohydrates were in the lower range of normal. Increased caloric intake lowered most of the elevated Phe- and BCAA- concentrations.

Agenesis of the corpus callosum, abnormal genitalia and intractable epilepsy due to a novel familial mutation in the Aristaless-related homeobox gene

Mutations in the Aristaless-related homeobox (ARX) gene are associated with a broad spectrum of disorders including X-linked lissencephaly with abnormal genitalia (XLAG) and absent corpus callosum. Here, we describe a family with two male infants suffering from agenesis of the corpus callosum (ACC), intractable epilepsy, and abnormal genitalia. The phenotype of both affected patients differed in severity of the cerebral malformation with one showing no obvious evidence for lissencephaly. Both infants lacked any psychomotor development and died at the age of 17 weeks and 18 months, respectively. Genetic analysis of the ARX gene revealed a novel frameshift mutation in exon 4 (nt1419_1420insAC) leading to a shortened protein lacking the aristaless domain. In summary, analysis of the ARX gene should not only be considered in male patients with typical features of XLAG but also in those presenting with early onset epilepsy, ACC, and abnormal genitalia without obvious neuroradiological features of lissencephaly.

Glutaric aciduria I: creatine supplementation restores creatinephosphate levels in mixed cortex cells from rat incubated with 3-hydroxyglutarate

The pathogenesis of neurological sequelae in glutaric aciduria I (GA I) is still unclear. Some evidence exists for compromised energy generation in the brain of patients with GA I resulting in 'slow-onset' excitotoxicity. Previously, we have shown a reduced activity of the mitochondrial ATPsynthase in cultured mixed cortex cells from neonatal rats incubated with 2-4mM 3-hydroxyglutarate (3-OH glut) for 24h. In the present study we measured cellular contents of high energy phosphate compounds (creatinephosphate CP, ATP, and ADP) in this model after a 24h incubation period with 2-4mM glutarate (glut) or 3-OH glut. 3-OH glut specifically led to a reduction of CP content in a dose-dependent manner, whereas concentrations of ATP, ADP, and AMP remained unchanged. The drop in CP-concentration could be prevented by preincubation with the non-competitive NMDA-receptor antagonist MK 801 or coincubation with 1mM creatine. NMDA-receptor associated ion channels may be opened due to a lack of energy inside the neurons caused by a reduction of CP. This is followed by membrane depolarization which could impair electrogenic creatine transport into the cell.

Altered levels of high-energy phosphate compounds in fibroblasts from different forms of neuronal ceroid lipofuscinoses: further evidence for mitochondrial involvement

The pathogenesis of neurodegeneration in neuronal ceroid lipofuscinosis (NCL) is still not clear despite progress in mutation analysis of these diseases. We have recently observed anomalies at the level of the mitochondrial ATPsynthase (complex V of the respiratory chain) in fibroblasts from children with CLN1, CLN2, CLN3 and in an ovine model (OCL6). The measurements were carried out in vitro. If these alterations were of relevance in vivo as well, contents of high-energy phosphate compounds should be reduced. In the present study, we measured levels of creatine phosphate (CP), ATP, ADP and AMP in fibroblasts from children with CLN1, CLN2, CLN3 and in OCL6. ATP was reduced to about 50% of normal in CLN1, CLN2 and CLN3, ADP was about 30% of normal in these cells, and CP was 50% of normal in CLN1 and CLN2 but remained normal in CLN3. In fibroblasts of NCL-sheep, however, CP and ADP were increased to 690% and 220% of normal, respectively, while ATP remained normal. If the anomalies found in cellular energy metabolism in fibroblasts were expressed in neurons from NCL patients and NCL sheep 'slow-onset excitotoxicity' could occur leading to cellular dysfunction and eventually to cell death.

Glutaric aciduria type I: pathomechanisms of neurodegeneration

In organotypic corticostriatal and hippocampal slice cultures from rat brain, 3-hydroxyglutaric acid but not glutaric and glutaconic acids induced neurodegeneration by activation of NMDA receptors. Electrophysiological investigations (Xenopus laevis oocytes expressing glutamate receptors; rat mixed cortex culture) revealed no direct interaction of 3-hydroxyglutaric acid with glutamate receptors. We speculate that 3-hydroxyglutaric acid induces a mild energy deprivation that interferes with the voltage-dependent Mg(2+)-block of NMDA receptors.

Requirement of metabotropic glutamate receptors for the generation of inflammation-evoked hyperexcitability in rat spinal cord neurons

In the central nervous system the transmitter L-glutamate activates both ionotropic receptors coupled to cation channels and metabotropic receptors coupled to G-proteins. The role of metabotropic receptors in the processing of mechanosensory and nociceptive information was studied in a subset of spinal cord neurons with afferent input from the knee joint in anaesthetized rats using electrophysiological methods. The ionophoretic administration of L-2-amino-3-phosphonopropionic acid (L-AP3), an antagonist at the metabotropic receptor, had no effect on the responses to innocuous and noxious pressure applied to the normal knee joint, although the antagonist prevented the potentiation of these responses evoked by the ionophoretic administration of a specific agonist at the metabotropic receptor, trans-(+/-)-1-amino-(1S,3R)-cyclopentane-dicarboxylic acid (t-ACPD). By contrast, in neurons that were rendered hyperexcitable by acute inflammation in the knee joint L-AP3 reduced the responses to pressure applied to the knee. When L-Ap3 was applied during induction of inflammation and throughout the subsequent 1.5 h the spinal neurons did not develop hyperexcitability over this time period. L-AP3 did not impair the activation of ionotropic N-methyl-D-aspartate (NMDA) and non-NMDA receptors by the specific agonists. We conclude that spinal metabotropic glutamate receptors are not involved in the mediation of responses to innocuous and noxious mechanical stimuli applied under normal conditions. They are required, however, for the generation of inflammation-evoked hyperexcitability of spinal cord neurons, a form of functional plasticity underlying the painfulness in pathophysiological conditions such as inflammation.

The involvement of N-methyl-D-aspartate (NMDA) and non-NMDA receptors in the responsiveness of rat spinal neurons with input from the chronically inflamed ankle

Unilateral adjuvant inflammation was induced at the rat ankle 2 or 20 days before an evaluation of the contribution of N-methyl-D-aspartate (NMDA) and non-NMDA receptors to the processing of nociceptive information by wide dynamic range neurons in the spinal cord. Microionophoretic application of either the NMDA receptor antagonists ketamine and DL-2-amino-5-phosphonovalerate (AP5) or the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) reduced the responses to innocuous and noxious mechanical stimulation of the inflamed ankle. The pattern of these effects was comparable to that in rats with acute inflammation suggesting that non-NMDA and NMDA receptors are similarly involved in acute, prolonged acute and chronic inflammation-evoked activity.

Electrophysiological evidence for a spinal antinociceptive action of dipyrone

Electrophysiological experiments in anesthetized cats and rats were performed in order to study the effects of dipyrone on single afferent fibers from the knee joint and on spinal cord neurons with knee joint input. The neurons were activated and/or rendered hyperexcitable by an acute inflammation in the knee joint. In the joint nerve in cats, intravenous dipyrone (25-100 mg/kg) reduced ongoing activity in 10/12 thinly myelinated afferents but only in 1/10 unmyelinated afferents; the responses to movements of the inflamed knee were reduced in 8/10 thinly myelinated but only in 3/10 unmyelinated units. The reduction of activity was significant 20-30 min after application and was maximal at 60-180 min. In the spinal cord of spinalized cats, intravenous dipyrone (25-100 mg/kg) reduced ongoing activity and/or responses to pressure onto the inflamed knee in 14/16 neurons and in non-spinalized rats similar effects were seen in 10/11 neurons. Effects on spinal cord neurons started 5-10 min after application and were maximal after 20-40 min. These data show pronounced suppression of inflammation-induced nociception by dipyrone and they suggest that the spinal cord is a major site of action of this compound.

N-methyl-D-aspartate (NMDA) and non-NMDA receptor antagonists block the hyperexcitability of dorsal horn neurons during development of acute arthritis in rat's knee joint

1. In 22 anesthetized rats we studied the involvement of N-methyl-D-aspartate (NMDA) and non-NMDA receptors in the generation and maintenance of hyperexcitability in spinal cord neurons with knee input that develops in the course of an acute inflammation in the knee. In all experiments one neuron with knee input was identified, and the responses to mechanical stimuli and the receptive fields were monitored before and after induction of inflammation by the intra-articular injections of kaolin and carrageenan into the joint cavity. In most experiments multibarrel electrodes were used to administer specific NMDA and non-NMDA antagonists ionophoretically close to the neuron to test their effects on the inflammation-evoked changes. 2. Six neurons in the deep dorsal horn in six rats were used to establish the time course of the development of hyperexcitability in the untreated animal. In control periods of up to 3 h, the responses to mechanical stimuli and the receptive fields were stable. After induction of inflammation, the neurons developed increased responsiveness to mechanical stimuli applied to the injected knee but also to mechanical stimuli applied to the ipsilateral ankle and paw (including a reduction in the mechanical threshold in nociceptive specific neurons). The receptive fields expanded in five out of six neurons. The changes of responsiveness occurred mainly in the 2nd to 3rd h after the injection of kaolin. 3. In four rats three to four intravenous injections of the NMDA antagonist ketamine (2 mg/kg) were given during the injections of kaolin and carrageenan and in the following periods (up to 101 min postkaolin). During this treatment none of the four neurons exhibited the changes of responsiveness that were usually seen in control animals, although swelling of the knee developed in the same fashion as in control rats. Similarly, the generation of hyperexcitability was prevented when the NMDA antagonists ketamine and DL-2-amino-5-phosphonovalerate (AP5) were administered ionophoretically (ketamine in 4, AP5 in 2 rats) during the injections of kaolin and carrageenan and up to 100 min postkaolin. The doses of ketamine and AP5 were sufficient to reduce the responses to NMDA, whereas the responses to the non-NMDA agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) were not influenced. 4. The ionophoretic application of the non-NMDA antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) during the injections of the kaolin and carrageenan and up to 103 min postkaolin also prevented the generation of hyperexcitability in six neurons in six rats.(ABSTRACT TRUNCATED AT 400 WORDS)

The clinically available NMDA receptor antagonist memantine is antinociceptive on rat spinal neurones

In anaesthetized rats antinociceptive effects of the clinically available drug memantine, an NMDA (N-methyl-D-aspartate) antagonist in vitro, were evaluated using extracellular recordings from spinal neurones with knee joint input. Memantine (1-12 mg kg-1) was applied intravenously before (control animals) or after induction of an acute knee joint inflammation which rendered spinal neurones hyperexcitable. Memantine (2 mg kg-1, i.v.) selectively reduced the responses to ionophoretic application of NMDA close to the neurone but not those to AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid). In control animals memantine reduced the neurones' responses to noxious but not to innocuous pressure on to the knee. In rats with acute arthritis memantine reduced the responses to noxious and innocuous pressure. Thus memantine may be useful for the treatment of pain states.

Differential effects of N-methyl-D-aspartate (NMDA) and non-NMDA receptor antagonists on the responses of rat spinal neurons with joint input

In anaesthetized rats the involvement of N-methyl-D-aspartate (NMDA) and non-NMDA receptors in the processing of innocuous and noxious sensory inflow from joints was assessed in 27 spinal dorsal horn neurons. Microionophoretic application of either the NMDA antagonists ketamine and D,L-2-amino-5-phosphonovalerate (AP5) or the non-NMDA antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) reduced the responses to noxious compression of the knee and ankle joint. By contrast, the responses to innocuous pressure were consistently reduced by CNQX but only exceptionally by NMDA antagonists. Therefore non-NMDA receptors are involved in the processing of innocuous and noxious mechanical stimuli applied to the normal joint whereas NMDA receptors are activated mainly by nociceptive input.