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Biomedical subjects

H R Jones

Publications and source records attributed to H R Jones.

At least 19 recordsLinked to original sources
PubMed2003

Clinically disparate stiff-person syndrome with GAD65 autoantibody in a father and daughter.

Stiff-person syndrome (SPS) is a sporadic autoimmune disorder characterized by muscle stiffness with painful spasms and usually a high level of GAD65 antibody. The authors report familial SPS associated with GAD65 antibody. The clinical presentations were disparate; the father had an appendicular form of SPS and the daughter's axial SPS presented with episodic opisthotonos.

Adult↗
PubMed2001

Pseudomeningoencephalitic presentation of pediatric Guillain-Barré syndrome.

Guillain-Barré syndrome is an acute, autoimmune polyradiculoneuropathy that improves with immune-modulating treatment if instituted early in the illness. Preliminary diagnosis relies on the clinician's recognition of the typical symptoms and signs as supporting evidence of the illness, such as nerve conduction studies, which may not be available emergently. We report eight children with Guillain-Barré syndrome in whom the initial presentation was atypical and suggested a primary central nervous system illness. In these patients, the predominant clinical symptoms included drowsiness, headache, irritability, and meningismus, although the classic features of Guillain-Barré syndrome (weakness, hyporeflexia) were also present. The atypical presentation caused delay in diagnosis in some cases. It is important to recognize this variant of pediatric Guillain-Barré syndrome to ensure expeditious diagnosis and treatment.

Child↗
PubMed2000

Acute care pediatric electromyography.

The recognition of uncommon pediatric motor unit disorders or unusual clinical presentations of common illnesses, such as Guillain-Barré syndrome (GBS), have increased the need for electromyography (EMG) in childhood critical care units. There are two different clinical sets, one appropriate to newborns and infants and the other to older children. Some illnesses that present as an acute floppy infant are not found in the differential diagnosis of motor unit disorders in the older child or adult. These include spinal muscular atrophy, postvaccine poliomyelitis, intrauterine GBS, infantile botulism, and severe myopathies, such as myotonia dystrophy, and some glycogen storage diseases. An appreciation of the neurophysiological maturational norms is essential to an effective pediatric EMG consultation for children ages 0-3 years. Additionally, the neuromuscular complications of extended intubation and sepsis in children are gaining broader recognition. An increased dialogue between clinical neurophysiologists and pediatric neurologists and intensivists in both neonatal and pediatric intensive care units is essential.

Acute Disease↗
PubMed2000

Diagnosis of pediatric neuromuscular disorders in the era of DNA analysis.

Extraordinary breakthroughs in the molecular pathogenesis of muscle and nerve disease have resulted in an evolving genetic classification of neuromuscular disorders and the development of new diagnostic methods. This remarkable progress has introduced new genetic tests and has changed the indications for use of certain invasive diagnostic procedures in the evaluation of children with presumed disorders of the motor unit. In this review, we present the current diagnostic approach to the more common neuromuscular diseases of infancy and childhood and define the diagnostic role of muscle biopsy and pediatric electromyography/nerve conduction studies in the era of genetic analysis.

Blotting, Southern↗
PubMed2000

Guillain-Barré syndrome: perspectives with infants and children.

An acute flaccid paraparesis or ascending quadriparesis in an infant or child constitutes a very important pediatric neurology emergency. The Guillain-Barré syndrome (GBS) is the most frequent cause. This is primarily an autoimmune, post-infectious, demyelinating, peripheral nervous system process. A small percentage of children develop a primary axonal process not unlike that identified more commonly in China. Because of the potential for acute respiratory compromise, any child suspected of having GBS needs immediate hospitalization. The major considerations in differential diagnosis include transverse myelitis, toxic neuropathies, tick paralysis, infantile botulism, myasthenia gravis, and dermatomyositis. On occasion, some younger children present with an acute severe pain syndrome that may mask as a pseudo-encephalopathy. Another clinical variant is the Miller-Fisher syndrome characterized by ataxia, ophthalmoparesis, and areflexia. This is associated with a high frequency of the anti-GQ-1-b antibodies. Although most children with GBS have a relatively benign clinical course, some become very ill and require intubation with intensive care monitoring. Immunomodulating treatment should be used for any child who loses the ability to walk. To date, no well-controlled study has been completed analyzing the relative merits of the two most commonly used therapies, namely plasmapheresis or intravenously administered immunoglobulin.

Acute Disease↗
PubMed1998

Mutilating hand syndrome in an infant with familial carpal tunnel syndrome.

A 7-month-old infant, son of consanguinous Indian parents, presented with recurrent chewing of his digits in a median nerve distribution as the primary manifestation of carpal tunnel syndrome, in conjunction with features consistent with congenital insensitivity to pain. Electromyography (EMG) demonstrated severe median nerve entrapment at the wrist bilaterally, but other nerves were normal. In spite of clinical evidence of diffuse pain insensitivity, sural nerve and skin biopsies were normal, and he had no evidence of autonomic dysfunction. Hand findings evolved with scarring and infection of median innervated digits and loss of fine motor skills. Carpal tunnel release resulted in complete clinical resolution and significant EMG improvement. Milder symptoms and EMG evidence of median nerve entrapment were demonstrated in both parents, paternal grandparents, and several of his father's siblings. We hypothesize this child may be homozygous for a mutant allele that in its heterozygous state predisposes to familial autosomal dominant carpal tunnel syndrome. Homozygosity for this or another mutant allele may be responsible for his congenital insensitivity to pain.

Action Potentials↗
PubMed1997

Studies of the hydrodynamic volume changes that occur during refolding of lysozyme using size-exclusion chromatography.

A size-exclusion chromatography-based refolding process (SEPROS) has successfully been used to renature lysozyme at high concentrations. This process is based on the different hydrodynamic characteristics of folded and unfolded proteins and their interaction with gel filtration media. In this paper we have quantified the changes in Stokes radius, hydrodynamic volume and partition coefficient that occur when lysozyme is refolded from urea in a size-exclusion column. In 8 M urea partially folded and unfolded lysozyme were resolved using Superdex 75 HR. These two species were present at approximately the same concentration. As the urea concentration was decreased the unfolded species gradually decreased until at 4 M urea only partially folded lysozyme remained, which continued to fold on further reduction of the urea concentration. Using these results the initial mechanism for size exclusion chromatography protein refolding has been confirmed.

Buffers↗
PubMed1997

Infantile phosphofructokinase deficiency with arthrogryposis: clinical benefit of a ketogenic diet.

We report a 2-year-old boy with phosphofructokinase deficiency presenting in the newborn period with congenital arthrogryposis and severe myopathy, who has had significant improvement on a ketogenic diet since its institution at 4 months of age. We provide a rationale for use of this treatment and hypothesize it may be beneficial in other patients with phosphofructokinase deficiency and progressive muscular involvement. Confirmation awaits further clinical trials in carefully selected patients.

Arthrogryposis↗
PubMed1996

Intrauterine onset of a mononeuropathy: peroneal neuropathy in a newborn with electromyographic findings at age one day compatible with prenatal onset.

Mononeuropathies are unusual at birth, and electromyographic (EMG) definition the first day of life has not been reported previously. Although neonatal mononeuropathies may be related to obstetric complications, prenatal mechanisms also merit consideration. We report an infant, born with a peroneal neuropathy, whose EMG was performed 18 h after birth. An isolated peroneal nerve lesion with lack of compound muscle action potential and the presence of fibrillation potentials, confined to the tibialis anterior muscle, suggested a primary intrauterine mechanism for this mononeuropathy. Because of an infant's small size, the temporal profile used in adults for appearance of EMG signs of wallerian degeneration may not apply. Inaccurate conclusions may result if the EMG standards for timing adult nerve injury are applied to newborns. To our knowledge, previous published cases of neonatal mononeuropathies have not included babies whose first EMG was performed before age 4 days. Therefore, an EMG study shortly after birth needed to be accomplished if strong support for the hypothesis of a prenatal onset were to be generated. Our findings are compatible with an intrauterine onset of this baby's peroneal neuropathy.

Electromyography↗
PubMed1996

Pediatric radial mononeuropathies: a clinical and electromyographic study of sixteen children with review of the literature.

Sixteen pediatric radial mononeuropathies were seen among 2077 electromyograms performed in the electromyography laboratory at The Children's Hospital, Boston, during 16.5 years, 1979-1995. Eight (50%) of these radial neuropathies, including 2 in newborns with apparent prenatal onset, were atraumatic, primarily related to compression in 6 and entrapment in 2. The other 8 (50%) were traumatic related to fractures or lacerations. Electromyography documented the radial neuropathy to be localized to the proximal main radial nerve trunk in 2 (13%), distal main radial nerve trunk in 9 (56%), and posterior interosseous nerve in 5 (31%) children. Significant improvement was noted in 13 of the 16 radial neuropathies--within 6-12 weeks for demyelinating lesions and up to 17 months for axonal injuries. Rarely, a child with a chronic progressive radial neuropathy or a postfracture radial neuropathy that does not improve in 3 months may require exploration.

Adolescent↗
PubMed1996

Childhood Guillain-Barré syndrome: clinical presentation, diagnosis, and therapy.

A rapidly progressive, generally symmetric, ascending flaccid paraparesis or quadriparesis that develops in an infant or child constitutes an uncommon but important pediatric neurologic emergency that requires immediate evaluation and treatment. The differential diagnosis primarily includes acute neuropathies, most commonly the childhood Guillain-Barré syndrome and, rarely, acute transverse myelitis or infantile poliomyelitis. A clinical distinction may be difficult in the younger child in whom detailed sensory examination is not possible. Although most children with Guillain-Barré syndrome usually have a benign and relatively limited clinical illness, some become severely ill, requiring intubation and careful intensive monitoring. To date, no well-controlled multi-institutional studies of treatment with either plasmapheresis or intravenously administered immunoglobulin have been developed in children despite the success of these modalities in adults. A review of the data available using these therapies is included in this study.

Adult↗
PubMed1995

Guillain-Barré syndrome in children.

The Guillain-Barré syndrome is a pediatric neurologic emergency and the most common cause in children of rapidly evolving, usually flaccid, weakness with associated areflexia. Two treatable illnesses, namely tick paralysis and acute cord compression, demand immediate differential diagnosis. Rarely, poliomyelitis still mimics infantile Guillain-Barré syndrome. Specific precursor infections, such as Campylobacter jejuni, are now recognized to affect the clinical presentation of Guillain-Barré syndrome. Cerebrospinal fluid evaluation and electromyography are usually diagnostic; new modalities, such as anti-GM1 antibodies, magnetic resonance imaging, and magnetic stimulation, are being evaluated in childhood Guillain-Barré syndrome. Although most cases of Guillain-Barré syndrome have benign courses, all require initial respiratory and autonomic monitoring to prevent fatal outcomes. No well-controlled pediatric studies comparing plasmapheresis with intravenous immunoglobulin have occurred. Results of treatment with either modality are encouraging. A synopsis of these reports is included in this review.

Child↗
PubMed1994

Electromyography and biopsy correlation with suggested protocol for evaluation of the floppy infant.

Eighty infants with nonarthrogrypotic floppy infant syndrome (FIS) were evaluated between 1979 and 1990. Electromyographic data were correlated with results of muscle and nerve biopsies in 41 of 80 who had concomitant biopsies (38) or other diagnostic analyses (3). A diagnosis was made of Werdnig-Hoffmann disease (WHD) in 15, a congenital infantile polyneuropathy (IPN) in 3, neuromuscular transmission defect (NMTD) in 2, myopathy in 12, and presumed "central" hypotonia in 9. A very positive correlation rate between nerve conduction studies with electromyography and biopsy results was found in 93% (14 of 15) with WHD and 100% in IPN (3 of 3). However, only 4 of 10 infants (40%) with biopsy-proven myopathy had an abnormal EMG. Only once did the results of electromyography and biopsy conflict.

Biopsy↗