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Biomedical subjects

W Marques

Publications and source records attributed to W Marques.

17 recordsLinked to original sources
PubMed2005

Navier-Stokes-like equations for traffic flow.

The macroscopic traffic flow equations derived from the reduced Paveri-Fontana equation are closed starting with the maximization of the informational entropy. The homogeneous steady state taken as a reference is obtained for a specific model of the desired velocity and a kind of Chapman-Enskog method is developed to calculate the traffic pressure at the Navier-Stokes level. Numerical solution of the macroscopic traffic equations is obtained and its characteristics are analyzed.

Journal Article↗
PubMed2005

Effect of treatment of dentofacial deformities on the electromyographic activity of masticatory muscles.

Individuals with dentofacial deformities present changes in masticatory muscles. The objective of the present study was to determine the influence of interdisciplinary treatment in cases of class III dentofacial deformities regarding the EMG activity of the temporal (T) and masseter (M) muscles. The study was conducted on 15 patients with class III dentofacial deformities who were submitted to orthodontic, oromyofunctional and surgical treatment and assigned to groups P1 (before surgery) and P2 (6-9 months after surgery). Fifteen individuals with no alterations in facial morphology or dental occlusion and without signs or symptoms of temporomandibular joint dysfunction were used as controls (CG). The T and M muscles were submitted to EMG bilaterally in the situations of mastication and mastication plus biting, with analysis of amplitude interval and root mean square. For all muscles tested, there was a difference between CG, P1 and P2; CG was higher than P2 and P2 higher than P1 in all situations assessed. We conclude that there was an increase in EMG activity in the T and M muscles after surgical correction of the dentofacial deformity accompanied by interdisciplinary treatment, although the values were still lower than those obtained for CG.

Adult↗
PubMed2004

Hereditary motor and autonomic neuronopathy 1 maps to chromosome 20q13.2-13.3.

The spinal muscular atrophies (SMA) or hereditary motor neuronopathies result from the continuous degeneration and death of spinal cord lower motor neurons, leading to progressive muscular weakness and atrophy. We describe a large Brazilian family exhibiting an extremely rare, late-onset, dominant, proximal, and progressive SMA accompanied by very unusual manifestations, such as an abnormal sweating pattern, and gastrointestinal and sexual dysfunctions, suggesting concomitant involvement of the autonomic nervous system. We propose a new disease category for this disorder, 'hereditary motor and autonomic neuronopathy', and attribute the term, 'survival of motor and autonomic neurons 1' (SMAN1) to the respective locus that was mapped to a 14.5 cM region on chromosome 20q13.2-13.3 by genetic linkage analysis and haplotype studies using microsatellite polymorphic markers. This locus lies between markers D20S120 and D20S173 showing a maximum LOD score of 4.6 at D20S171, defining a region with 33 known genes, including several potential candidates. Identifying the SMAN1 gene should not only improve our understanding of the molecular mechanisms underlying lower motor neuron diseases but also help to clarify the relationship between motor and autonomic neurons.

Chromosome Mapping↗
PubMed2004

Dejerine-Sottas' neuropathy caused by the missense mutation PMP22 Ser72Leu.

OBJECTIVE: To describe a patient with the Dejerine-Sottas' syndrome due to a de novo Ser72Leu amino acid substitution in the PMP22 protein and summarize the phenotype associated with this frequent mutation. CASE REPORT: The proband has a medical history of early onset, severe, and progressive demyelinating neuropathy, accompanied by mild ptosis and limitations of eye movements. Ulnar nerve motor conduction velocities were extremely reduced (2.6 and 2.2 m/s), and the sural nerve biopsy showed onion bulbs and thinly myelinated axons. Duplication of chromosome 17p11.2 was ruled out, and the Ser72Leu substitution was found upon sequencing the PMP22 gene. CONCLUSION: The Ser72Leu substitution is being confirmed as the most frequent point mutation in the PMP22 gene. This 'hot spot' should be considered in the strategy of looking for point mutations in the hereditary demyelinating neuropathies.

Adolescent↗
PubMed2003

Surgical outcome in mesial temporal sclerosis correlates with prion protein gene variant.

BACKGROUND: Mesial temporal lobe epilepsy related to hippocampal sclerosis (MTLE-HS) is the most common surgically remediable epileptic syndrome. Ablation of the cellular prion protein (PrP(c)) gene (PRNP) enhances neuronal excitability of the hippocampus in vitro and sensitivity to seizure in vivo, indicating that PrP(c) might be related to epilepsy. OBJECTIVE: To evaluate the genetic contribution of PRNP to MTLE-HS. METHODS: The PRNP coding sequence of DNA from peripheral blood cells of 100 consecutive patients with surgically treated MTLE-HS was compared to that from a group of healthy controls adjusted for sex, age, and ethnicity (n = 180). The presence of PRNP variant alleles was correlated with clinical and presurgical parameters as well as surgical outcome. RESULTS: A variant allele at position 171 (Asn-->Ser), absent in controls, was found in heterozygosis (Asn171Ser) in 23% of patients (p < 0.0001). The PRNP genotypes were not correlated with any clinical or presurgical data investigated. However, patients carrying the Asn171Ser variant had a five times higher chance of continuing to have seizures after temporal lobectomy (95% CI 1.65 to 17.33, p = 0.005) than those carrying the normal allele. At 18 months after surgery, 91.8% of patients with the normal allele at codon 171 were seizure free, in comparison to 68.2% of those carrying Asn171Ser (p = 0.005). CONCLUSIONS: The PRNP variant allele Asn171Ser is highly prevalent in patients with medically untreatable MTLE-HS and influences their surgical outcome. The results suggest that the PRNP variant allele at codon 171 (Asn171Ser) is associated with epileptogenesis in MTLE-HS.

Adult↗
PubMed2003

Thr(118)Met amino acid substitution in the peripheral myelin protein 22 does not influence the clinical phenotype of Charcot-Marie-Tooth disease type 1A due to the 17p11.2-p12 duplication.

The Thr(118)Met substitution in the peripheral myelin protein 22 (PMP22) gene has been detected in a number of families with demyelinating Charcot-Marie-Tooth (CMT1) neuropathy or with the hereditary neuropathy with liability to pressure palsy, but in none of them has it consistently segregated with the peripheral neuropathy. We describe here a CMT1 family (a 63-year-old man, his brother and his niece) in which two mutations on different chromosomes were found in the PMP22 gene, the 17p duplication, detected by fluorescent semiquantitative polymerase chain reaction (PCR) of microsatellite markers localized within the duplicated region on chromosome 17p11.2-p12, and the Thr(118)Met substitution, detected by direct sequencing the four coding exons of the PMP22 gene. A genotype/phenotype correlation study showed that the neuropathy segregates with the duplication and that the amino acid substitution does not seem to modify the clinical characteristics or the severity of the peripheral neuropathy. We did not find any evidence to characterize this substitution as a polymorphism in the population studied and we propose that the high frequency reported for this point mutation in the literature suggests that the Thr(118)Met substitution may be a hotspot for mutations in the PMP22 gene.

Amino Acid Substitution↗
PubMed2003

Myalgia as the revealing symptom of multicore disease and fibre type disproportion myopathy.

BACKGROUND: Multicore disease and congenital fibre type disproportion myopathy are diseases assigned to the heterogeneous group of congenital myopathies. Although hypotonia and muscle weakness appearing in early life are the commonest manifestations of these diseases, distinct phenotypes and late onset cases have been described. OBJECTIVE: To report the occurrence of myalgia as the revealing symptom of multicore disease and fibre type disproportion myopathy. METHODS: The clinical cases of three patients with fibre type disproportion myopathy and one with multicore disease are described. Skeletal muscle biopsies were processed for routine histological and histochemical studies. RESULTS: The clinical picture was unusual in that the symptoms were of late onset and the predominant complaint was muscle pain exacerbated by exercise. Muscle weakness was found in only a single patient, the mother of a patient with fibre type disproportion myopathy. Physical examination was unremarkable in the other patients. Muscle biopsies from patients 1 and 2 contained type I fibres that were considerably smaller than the type II fibres, supporting the diagnosis of fibre type disproportion myopathy. Skeletal muscle of patient 4 showed multiple areas, predominantly but not exclusively in the type I fibres, from which oxidative enzyme activities were absent, as seen in multicore disease. CONCLUSIONS: Muscle pain was the main clinical manifestation in our patients. Recognition of the broader clinical expression of these myopathies is important for prognostic reasons and for genetic counselling of the family members.

Adolescent↗
PubMed2002

Free molecular sound propagation.

The sound propagation through a gas in the free-molecular regime is studied on the basis of the linearized collisionless Boltzmann equation. The two principal quantities that characterize the sound propagation, namely the phase and amplitude of the perturbation, are determined by taking into account the influence of the receptor. It is shown that at a small distance between the source and the receptor the presence of the last changes qualitatively the sound characteristics. Two phase velocities are introduced: a differential and an integral, which are different in the free molecular regime.

Journal Article↗
PubMed2000

Limitations on the clinical utility of the ulnar dorsal cutaneous sensory nerve action potential.

OBJECTIVE: To validate the clinical use of the ulnar dorsal cutaneous (UDCN) sensory nerve action potential (SNAP) in the topographical analysis of ulnar mononeuropathies and in the process of choosing a sensory nerve for biopsy. METHODS: We surveyed the UDCN SNAP electrophysiological characteristics in both hands of 97 normal volunteers aged 10-84 years. The nerve was recorded from the 4th intermetacarpal space with subcutaneous needle electrodes and percutaneous stimulation was carried out at the wrist. RESULTS: In agreement with other studies, the mean conduction velocity was 58. 6+/-6.7 m/s, but the mean and the lower normal value of the amplitude (32 and 14.7 microV) were significantly higher than previous known data. An important finding was that in 21% of our population study, the UDCN SNAP was absent on at least one side, or a significant degree of asymmetry between the left and right sides was present. CONCLUSION: The UDCN SNAP is technically easy to obtain, but the high frequency of asymmetric or absent potentials detected in this study implies that caution should be taken in using this SNAP in clinical practice.

Action Potentials↗
PubMed1999

Phenotypic variation of a new P0 mutation in genetically identical twins.

We have identified a new point mutation in the myelin protein zero (P0) gene in two genetically identical twins with a demyelinating neuropathy. The G to A transition at nucleotide position 382 caused an aspartic acid to asparagine substitution in exon 3. Moreover, we found clear clinical differences which were most evident at an early age. These observations suggest that the expression of this P0 mutation may be susceptible to external, non-genetic influences that may act early in the course of the disease to alter the phenotype.

Adult↗
PubMed1999

Male monozygotic twins discordant for periventricular nodular heterotopia and epilepsy.

PURPOSE: To determine zygosity and study cerebral structure in apparently identical twins with discordant manifestation of focal epilepsy. METHODS: Male twins in their fifth decade were scanned by using magnetic resonance imaging (MRI) to detect structural abnormalities. Zygosity was determined by using 10 microsatellite markers. RESULTS: DNA analysis showed that the twins were >99.99% likely to be monozygous; they were discordant for bilateral symmetric periventricular nodular heterotopia (PNH) and epilepsy. CONCLUSIONS: The discordant occurrence of PNH and epilepsy in monozygotic male twins carries implications with respect to somatic mosaicism, currently held to be responsible for PNH in affected male subjects.

Brain Diseases↗
PubMed1998

Dejerine-Sottas neuropathy and PMP22 point mutations: a new base pair substitution and a possible "hot spot" on Ser72.

The occurrence of mutations in peripheral myelin protein 22 is one of the genetic mechanisms associated with Dejerine-Sottas neuropathy (DSN). On direct sequencing 2 of such patients we have found the first mutation in the third transmembrane domain associated with this neuropathy and the fourth Ser72Leu. We propose that the Ser72 may be a "hot spot" for DSN and that this should be considered for molecular analysis.

Adult↗
PubMed1997

The phenotypic manifestations of chromosome 17p11.2 duplication.

Clinical and electrophysiological investigations and nerve biopsies were carried out on 61 patients shown to have a chromosome 17p11.2 duplication (hereditary motor and sensory neuropathy-HMSN Ia). Of these, 50 showed a Charcot-Marie-Tooth (CMT) phenotype and eight could be classified as having the Roussy-Lévy syndrome. Of the patients with a CMT phenotype, three had associated pyramidal signs and of these one had 'complicated' HMSN and also signs of cerebellar and bulbar involvement. Diaphragmatic weakness was present in three severely affected cases, one of whom also had denervation of the anal sphincter associated with faecal incontinence. One unusual case presented in middle life with incapacitating muscle cramps associated with calf hypertrophy and only mild clinical signs of neuropathy. Prominent distal sensory loss was a consistent feature in one family, resulting in acrodystrophic changes in several members. Concurrent focal peripheral nerve lesions were seen with both the CMT and Roussy-Lévy phenotypes, in seven patients. Upper limb motor nerve conduction velocity was 19.9 m/s +/- 1.3 (SEM), range 5-34 m/s. This corresponds to values previously obtained for autosomal dominant HMSN I. This series consisted mainly of older patients with more advanced disease. In contrast to the findings in younger patients, in their nerve biopsies, myelin thickness tended to be relatively reduced for axon size, indicating remyelination and/or hypomyelination; there was also regression of the onion bulbs. It is concluded that the possession of two copies of the peripheral myelin protein 22 gene within the duplicated region on chromosome 17p gives rise to a range of phenotypes and not solely to a CMT syndrome, and that the pattern of histological change in the peripheral nerves alters with advance of the disease.

Adolescent↗
PubMed1994

Postsurgical idiopathic brachial neuritis.

Idiopathic brachial neuritis (IBN) is a well-recognized clinical syndrome characterized by brachial pain followed by a patchy amyotrophy of muscles in the shoulder girdle and arm innervated by individual branches of the brachial plexus. Postsurgical IBN has not been widely recognized since Parsonage and Turner's original description in which 10% of patients had antecedent surgery. We present 6 patients who 1-13 days postoperatively developed signs and symptoms which met the clinical and electrophysiologic criteria for IBN. Postsurgical neuralgic amyotrophy is an under-recognized clinical entity which in most cases is ascribed to brachial plexus stretch injuries occurring during anesthesia. Early recognition of this condition may prevent unnecessary surgical exploration and allow for a more accurate prediction of functional recovery.

Adult↗