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Biomedical subjects

R A Brumback

Publications and source records attributed to R A Brumback.

At least 19 recordsLinked to original sources

Rhabdomyolysis in childhood. A primer on normal muscle function and selected metabolic myopathies characterized by disordered energy production.

Patients with rhabdomyolysis present an important clinical problem. In acute episodes immediate treatment may be necessary to prevent significant morbidity and mortality. Evaluation of affected patients necessitates an understanding of basic muscle pathophysiology and of the variety of disturbances that can interfere with muscle energy metabolism. The physician must then pursue a systematic stepwise evaluation (Table 6) that includes obtaining relevant history and laboratory studies, as well as arranging for appropriate provocative testing and muscle biopsy. Once the diagnosis is established, patient and family counseling is necessary, particularly in genetic disorders. Unfortunately, specific therapies have not proven entirely successful, and treatment generally has been directed at reducing the severity of rhabdomyolytic episodes.

Child

A modified Da Fano silver stain for demonstration of neurons and dendrites in glycol methacrylate-embedded brain tissue.

Golgi impregnation techniques are commonly used for characterization of neurons and their dendritic and axonal processes. Most of the widely used techniques require processing of fresh brain tissues, which limits the amount of material available for study. Additionally, the stained blocks must be subsequently embedded in paraffin, which produces considerable cellular shrinkage and distortion artifacts. Modification by one investigator of an early silver impregnation technique, designed to demonstrate the Golgi apparatus, allowed demonstration of neurons and their dendritic processes. Our further modification of the later technique, along with embedding of the stained tissue in glycol methacrylate, permits detailed examination of neurons and their processes in formaldehyde-fixed neonatal human brains. In cerebellar sections, this modified technique impregnates nearly all Purkinje cells, elucidating the fine structural detail of the developing neuronal dendritic tree and spines.

Brain

Electrodiagnosis of compressive nerve lesions.

Electrodiagnostic studies provide valuable information that can be a useful adjunct to careful clinical evaluation in the diagnosis of compression neuropathy. Such studies can also help to predict the outcome of treatment and differentiate nerve injuries amenable to successful surgical intervention.

Electrodiagnosis

Cerebral abnormalities in thanatophoric dysplasia.

Neuropathologic evaluation of two infants with thanatophoric dysplasia displayed typical gross morphologic characteristics and a distinct pattern of brain malformations, including anomalies of the temporal lobe gyri and hippocampus, neuroglial heterotopias, fiber tract hypoplasia, and dysplasia of deep nuclei. Increased numbers of horizontal cells of Cajal-Retzius were striking in frequency and distribution. The pattern of abnormalities suggests arrest of cerebral cortical ontogeny late in development. As with the mucopolysaccharidoses, a shared common metabolic pathway is a potential mechanism for development of widespread bony and somatic abnormalities and associated central nervous system anomalies.

Brain

An adult-onset myopathy characterized by a double ring appearance of muscle fibers.

We report a 33-yr-old man with an unusual neuromuscular disorder characterized by progressive generalized weakness of 3 yr duration whose muscle biopsy showed a double ring appearance in most muscle fibers. This double ring appearance was due to a peripheral outer sarcoplasmic mass and an inner ring of annular myofibrils surrounding a core of normal longitudinally oriented myofibrils. Nerve conduction studies were normal. Electromyography showed fibrillations, positive waves, and increased brief duration, low amplitude, polyphasic potentials.

Adult

Neurological disease in xeroderma pigmentosum. Documentation of a late onset type of the juvenile onset form.

Xeroderma pigmentosum (XP) is an autosomal recessive, neurocutaneous disorder characterized by sunlight-induced skin cancers and defective DNA repair. Many XP children develop a primary neuronal degeneration. We describe 2 unusual XP patients who had a delayed onset of XP neurological disease. Somatic cell genetic studies indicated that they have the same defective DNA repair gene and are both in XP complementation group A. These 2 patients, together with a group A patient previously reported from London, establish as a distinct clinical entity the late onset type of the juvenile onset form of XP neurological disease. The functional capacity of these patients' cultured fibroblast strains to survive after treatment with ultraviolet radiation indicates that their DNA repair defect is less severe than that of typical group A patients who have a more severe neurodegeneration with an earlier symptomatic onset. The premature death of nerve cells in XP patients (which is presumably due to their inherited defects in DNA repair mechanisms) suggests that normal repair of damaged DNA in neurons is required to maintain integrity of the human nervous system.

Adolescent

Spontaneous haematomyelia: a necropsy study.

Spontaneous haematomyelia (intramedullary spinal haematoma), is an uncommon event. Predisposing conditions have been reported including syringomyelia, pregnancy and delivery, angioma, spinal artery aneurysm, and haemophilia, but only rarely has a pathological evaluation been performed. Two such cases studied at necropsy are reported. In one case, the haematoma was restricted to the cervical spinal cord, while in the second case it extended from the medulla into the lowest thoracic cord segments. In both cases the haematomyelia was fatal. In the first case the clinical course was subacute, but in the other the course was more acute. Careful neuropathological examination showed no apparent cause for the haemorrhages.

Aged

Absence of beta-amyloid immunoreactivity in mesial temporal lobe in Cockayne's syndrome.

Cockayne's syndrome is associated with dementia and other physical signs of premature senescence. Death usually occurs in the first or second decade of life. Because previous neuropathologic descriptions have included neurofibrillary tangles and calcific and dystrophic cerebrovascular changes, we examined the mesial temporal lobes of three children with Cockayne's syndrome (confirmed by 254-nm ultraviolet light studies). Immunohistochemistry was used to determine if beta-amyloid immunoreactivity was present in the parenchyma or cerebral blood vessels. Tissues from the mesial temporal lobe of patients with Alzheimer's disease and Down syndrome were used as controls. None of the three temporal lobes from patients with Cockayne's syndrome contained beta-amyloid immunoreactive material in either the parenchyma or vessels; all of the Alzheimer's disease and Down syndrome controls had beta-amyloid immunoreactivity.

Alzheimer Disease

Selective type II muscle fiber hypertrophy in severe infantile spinal muscular atrophy.

The diagnostic muscle biopsy finding in severe infantile spinal muscular atrophy (Werdnig-Hoffmann disease, SMA type 1) is considered to be large-group atrophy with isolated clusters of hypertrophic type I myofibers. We present a unique case of severe infantile spinal muscular atrophy with selective hypertrophy of type II myofibers. A male infant presented at age 2 months with breathing difficulties and by age 4 months was hypotonic and weak. Electromyography revealed denervation in all extremity muscles, and nerve conduction velocities were normal but with small compound muscle action potentials. Quadriceps muscle biopsy revealed many hypertrophied type II myofibers (myofibers with a mean least diameter of 25.4 microns). In contrast, the largest type I myofibers were 20 microns in least diameter (mean diameter, 14.9 microns), and there was a normal-size population of type II fibers (mean diameter, 15.7 microns). In addition, sheets of atrophic type I and type II fibers averaged 2.0 microns in least diameter. Sural nerve biopsy was normal. Breathing difficulties progressed, with death ensuing at age 5 1/2 months. Autopsy revealed atrophy of ventral spinal roots with normal dorsal roots. There was loss of anterior horn cells, while remnant neurons were reduced in size. No other pathologic changes were identified. This case indicates that in severe infantile spinal muscular atrophy, relative sparing of the motor units with type II myofibers may occur.

Biopsy

Metabolic myopathy produced by acute inhibition of glyceraldehyde-3-phosphate dehydrogenase with ortho-iodosobenzoic acid.

A previously developed model of exercise-induced muscle contracture using iodoacetate to inhibit glyceraldehyde-3-phosphate dehydrogenase in rat hindlimb muscles produced selective type II myofiber damage. Utilizing a modification of the same model system, rats were given intra-aortic ortho-iodosobenzoic acid (700 nmol/kg body weight), which cleaves tryptophanyl peptides from glyceraldehyde-3-phosphate dehydrogenase. Within 2-4 h, spontaneous electrically-silent contracture developed in the injected musculature resulting in a plantar-flexed position of the hindlimb. After 24 h, the extensor digitorum longus and tibialis anterior muscles appeared grossly swollen (edematous) and discolored. Microscopically, the extensor digitorum longus (composed predominantly of type II myofibers) contained many randomly scattered, damaged myofibers, reduced glycogen content, absent glyceraldehyde-3-phosphate dehydrogenase activity, interstitial edema and focal collections of mononuclear phagocytes. Damaged fibers showed degenerative changes and contained stainable intracellular calcium. On modified trichrome-stained sections, an outer red staining rim of material was identifiable in many fibers. The fibers of the soleus muscle (composed predominantly of type I myofibers) were not damaged, indicating a preferential ortho-iodosobenzoic acid effect on type II myofibers.

Animals

Primary disorder of vigilance: a novel explanation of inattentiveness, daydreaming, boredom, restlessness, and sleepiness.

We present a novel condition, designated as a primary disorder of vigilance, that has symptoms which overlap those of attention deficit-hyperactivity disorder. Vigilance is the state of being watchful, awake, and alert. When vigilance is lost, the individual has difficulty sustaining attention. The most obvious evidence of lowered vigilance is motor restlessness (fidgeting and moving about, yawning and stretching, talkativeness, or a combination of these) to improve alertness when sitting or standing still or when involved in tasks requiring continuous mental performance. When prevented from being active to stay awake, persons with lowered vigilance will stare off, daydream, show minor hyperactivity, and finally may fall asleep. They will also have decreasing attention to current activities and usually avoid or lose interest in structured or repetitive activities (complaining of boredom and monotony). The primary disorder of vigilance (for which criteria have been established) is a dominantly inherited condition with onset in early childhood and worsening symptoms with age. Persons with the primary disorder of vigilance have a remarkably kind and caring temperament. When untreated this disorder can cause chronic failure at school and work, but when properly recognized it responds well to treatment with stimulant medication and schedules that avoid sameness and repetition.

Arousal

Cystic optic glioma.

A pilocytic astrocytoma of the optic nerve, chiasm, hypothalamus, or third ventricle is a relatively common tumor of childhood. This case report illustrates such a tumor, originating from this location, which is unusual because of the association with two very large cystic extensions into the middle cranial fossa and into the third ventricle. The massive size and extent of this tumor and cysts was demonstrated on a magnetic resonance imaging (MRI) scan, with gadolinium enhancement. This case illustrates a novel macroscopic appearance for a pilocytic glioma of the anterior third ventricle. The purpose of this report is to alert clinicians to the varied morphology this tumor may present as we apply increasingly our improved radiological, operative, and histopathological techniques.

Astrocytoma

Spongiform encephalopathies: the physician's responsibility.

The spongiform encephalopathies encompass several diseases affecting humans and animals. In the United States, the most common of these disorders in humans is Creutzfeldt-Jakob disease. The most frequent manifestations include dementia, pyramidal tract signs, and extrapyramidal movement disorder. Several clinically distinct syndromes can be identified. Often the diagnosis is confused with other forms of dementia, and the only definitive method for establishing the diagnosis is autopsy evaluation of brain tissue. Unfortunately, since the recognition of the infectious etiology of Creutzfeldt-Jakob disease, fear has often unreasonably interfered with clinical care and autopsy evaluation of affected patients. In actuality, because of the low and restricted infectivity of the responsible agent, affected individuals present minimal risks to clinical caretakers, and handling of patient specimens is not dangerous if appropriate precautions are taken. These precautions are well established, and physicians and other health care workers should not refuse care of appropriate evaluation (including autopsy) to individuals with suspected Creutzfeldt-Jakob disease.

Aged