Paul Maertens

Bio: Paul Maertens is an academic researcher from University of South Alabama. The author has contributed to research in topics: Medicine & Infarction. The author has an hindex of 11, co-authored 28 publications receiving 514 citations. Previous affiliations of Paul Maertens include University of Mississippi Medical Center.

Elevated plasma gamma-aminobutyric acid (GABA) levels in autistic youngsters: stimulus for a GABA hypothesis of autism

Abstract: Background Autistic Disorder is an early-onset developmental disorder with severe lifelong impact on social functioning, communication, and behavior. There is currently no marker or cure. The pathophysiology and etiology are obscure. Evidence for abnormal gamma-aminobutyric acid (GABA) function in Autistic Disorders is limited. A few case-reports and small studies have reported differences in GABA levels in plasma, platelets, and urine, compared to controls. Further studies on abnormalities of GABA function in Autistic Disorder are warranted. Material/methods Plasma GABA levels were measured using a new and sensitive technique, based on gas chromatography/mass spectrometry, in a small group of youngsters with Autistic Disorder and Attention-Deficit/Hyperactivity Disorder. Participants were outpatients between ages 5-15, satisfying modern criteria for these disorders. Results Elevated plasma GABA levels were found in youngsters with Autistic Disorder. Psychotropic medications did not seem to affect plasma GABA levels in this study. Plasma GABA levels decreased with age. Conclusions Elevated plasma GABA levels may be a biochemical marker of Autistic Disorder. This study supports the hypothesis that GABAergic mechanisms play a role in the etiology or pathophysiology of Autistic Disorder. However, the hypothesis remains unspecified owing to lack of research. Future studies on the clinical associations of seizure disorders, mood disorders, and catatonia in autistic people may provide the necessary data to formulate a coherent theory of GABA dysfunction in Autistic Disorder. More trials of medication with known or suspected effects on GABA function are warranted.

Clinical manifestations of mitochondrial DNA depletion

Abstract: Objective We studied five new patients with mitochondrial DNA (mtDNA) depletion to better define the clinical spectrum of this disorder. Background mtDNA depletion has been associated with myopathy or hepatopathy, or both, in infants and young children. Involvement of the CNS and peripheral nervous system has not been clearly established. Methods We reviewed the clinical course and performed morphologic, biochemical, and genetic analyses of muscle samples from five patients. Results Age at onset ranged from 3 months to 5 years, and one patient survived until age 10% years. Two patients had laboratory and clinical features reminiscent of dystrophinopathy, two had evidence of brain involvement, and two had peripheral neuropathy. Muscle biopsy specimens in all patients showed abundant ragged-red fibers. Biochemistry showed cytochrome c oxidase deficiency in all patients tested and decreased activities of other respiratory chain complexes in some. Conclusions Inheritance appeared to be autosomal recessive, suggesting that mutations in nuclear DNA are responsible for mtDNA depletion. mtDNA depletion should be considered in children with mitochondria1 disorders of uncertain etiology, and criteria for diagnosis are proposed.

Guillain-Barré syndrome with unilateral peripheral facial and bulbar palsy in a child: A case report.

Abstract: Guillain–Barre syndrome is characterized by progressive motor weakness, sensory changes, dysautonomia, and areflexia. Cranial nerve palsies are frequent in Guillain–Barre syndrome. Among cranial ne...

Cerebellar hemorrhage: a major morbidity in extremely preterm infants.

Abstract: To determine the impact of cerebellar hemorrhage (CH) on mortality and adverse neurodevelopmental (ND) outcome rates in extremely preterm infants admitted to a tertiary neonatal unit. A total of 1120 eligible infants (<28 weeks gestation) were born from 1998 to 2008 and had at least one cranial ultrasound. ND outcome was determined at 12 to 18 months corrected age. Most CH (75%) occurred in infants <25 weeks gestation. CH did not affect mortality rates, however, it was associated with both mental and motor impairments, with incidence rate ratios of 3.08 (1.71 to 4.84) and 2.12 (1.12 to 3.45), respectively. Moreover, the risk of cerebral palsy (CP) was increased in infants with CH involving the medial part of the cerebellum. Our findings substantiate recent reports about the cerebellum, highlighting its role in cognitive and executive functions, and associating early cerebellar injury not only with CP but also with learning, affective and behavioral disorders.

Anti-musk antibody after thymectomy in a previously seropositive myasthenic child

Abstract: We report a young girl with myasthenia gravis (MG) who was first seen at age 2 for unexplained falls, diplopia, and ptosis. The patient was born as a full-term spontaneous vaginal delivery and spoke her first words and started walking at the age 10 months. The child was physically active initially and loved to play and run. At age 27 months, the patient started having difficulty rising up while she was lying or sitting. She also experienced increasing difficulty swallowing without any dyspnea. Diagnostic workup at age 2 revealed a positive neostigmine test with improved muscle strength. Electromyography showed a decrement of 20 to 28% with 3- and 10-Hz repetitive stimulation in two nerve muscle pairs; anti-acetylcholine receptor antibody (anti-AChR Ab) levels were 0.6 and 1.3 on consecutive testing (N 0 to 0.4). Chest radiograph and CT scan did not reveal any additional findings. …

Guillain-Barré Syndrome Associated with SARS-CoV-2.

Abstract: Guillain–Barre Syndrome with Covid-19 Five patients who had Guillain–Barre syndrome 5 to 10 days after the onset of Covid-19 are described. Three had severe weakness and an axonal pattern on electr...

Human Coronaviruses and Other Respiratory Viruses: Underestimated Opportunistic Pathogens of the Central Nervous System?

Abstract: Respiratory viruses infect the human upper respiratory tract, mostly causing mild diseases. However, in vulnerable populations, such as newborns, infants, the elderly and immune-compromised individuals, these opportunistic pathogens can also affect the lower respiratory tract, causing a more severe disease (e.g., pneumonia). Respiratory viruses can also exacerbate asthma and lead to various types of respiratory distress syndromes. Furthermore, as they can adapt fast and cross the species barrier, some of these pathogens, like influenza A and SARS-CoV, have occasionally caused epidemics or pandemics, and were associated with more serious clinical diseases and even mortality. For a few decades now, data reported in the scientific literature has also demonstrated that several respiratory viruses have neuroinvasive capacities, since they can spread from the respiratory tract to the central nervous system (CNS). Viruses infecting human CNS cells could then cause different types of encephalopathy, including encephalitis, and long-term neurological diseases. Like other well-recognized neuroinvasive human viruses, respiratory viruses may damage the CNS as a result of misdirected host immune responses that could be associated with autoimmunity in susceptible individuals (virus-induced neuro-immunopathology) and/or viral replication, which directly causes damage to CNS cells (virus-induced neuropathology). The etiological agent of several neurological disorders remains unidentified. Opportunistic human respiratory pathogens could be associated with the triggering or the exacerbation of these disorders whose etiology remains poorly understood. Herein, we present a global portrait of some of the most prevalent or emerging human respiratory viruses that have been associated with possible pathogenic processes in CNS infection, with a special emphasis on human coronaviruses.

Trends in Care Practices, Morbidity, and Mortality of Extremely Preterm Neonates, 1993-2012

Abstract: Obstet Gynecol Surv 2016;71(1):7–9Since the 1990s, there have been considerable changes in care for mothers in preterm labor and for extremely preterm infants. The Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network has monitored changes in this

Mutant mitochondrial thymidine kinase in mitochondrial DNA depletion myopathy

Abstract: The mitochondrial deoxyribonucleotide (dNTP) pool is separated from the cytosolic pool because the mitochondria inner membrane is impermeable to charged molecules The mitochondrial pool is maintained by either import of cytosolic dNTPs through dedicated transporters1,2 or by salvaging deoxynucleosides within the mitochondria; apparently, enzymes of the de novo dNTP synthesis pathway are not present in the mitochondria In non-replicating cells, where cytosolic dNTP synthesis is down-regulated, mtDNA synthesis depends solely on the mitochondrial salvage pathway enzymes, the deoxyribonucleosides kinases Two of the four human deoxyribonucleoside kinases, deoxyguanosine kinase (dGK) and thymidine kinase-2 (TK2), are expressed in mitochondria3,4,5,6 Human dGK efficiently phosphorylates deoxyguanosine and deoxyadenosine, whereas TK2 phosphorylates deoxythymidine, deoxycytidine and deoxyuridine Here we identify two mutations in TK2, histidine 90 to asparagine and isoleucine 181 to asparagine, in four individuals who developed devastating myopathy and depletion of muscular mitochondrial DNA in infancy In these individuals, the activity of TK2 in muscle mitochondria is reduced to 14–45% of the mean value in healthy control individuals Mutations in TK2 represent a new etiology for mitochondrial DNA depletion, underscoring the importance of the mitochondrial dNTP pool in the pathogenesis of mitochondrial depletion

The deoxyguanosine kinase gene is mutated in individuals with depleted hepatocerebral mitochondrial DNA.

Abstract: Mitochondrial DNA (mtDNA)-depletion syndromes (MDS; OMIM 251880) are phenotypically heterogeneous, autosomal-recessive disorders characterized by tissue-specific reduction in mtDNA copy number. Affected individuals with the hepatocerebral form of MDS have early progressive liver failure and neurological abnormalities, hypoglycemia and increased lactate in body fluids. Affected tissues show both decreased activity of the mtDNA-encoded respiratory chain complexes (I, III, IV, V) and mtDNA depletion. We used homozygosity mapping in three kindreds of Druze origin to map the gene causing hepatocerebral MDS to a region of 6.1 cM on chromosome 2p13, between markers D2S291 and D2S2116. This interval encompasses the gene (DGUOK) encoding the mitochondrial deoxyguanosine kinase (dGK). We identified a single-nucleotide deletion (204delA) within the coding region of DGUOK that segregates with the disease in the three kindreds studied. Western-blot analysis did not detect dGK protein in the liver of affected individuals. The main supply of deoxyribonucleotides (dNTPs) for mtDNA synthesis comes from the salvage pathway initiated by dGK and thymidine kinase-2 (TK2). The association of mtDNA depletion with mutated DGUOK suggests that the salvage-pathway enzymes are involved in the maintenance of balanced mitochondrial dNTP pools.