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Biomedical subjects

R J Barohn

Publications and source records attributed to R J Barohn.

104 records · Page 6Linked to original sources
PubMed1992

Improvement of the exercise test after therapy in thyrotoxic periodic paralysis.

The diagnosis of periodic paralysis (PP) can be aided by demonstrating a decrease in compound motor action potential (CMAP) amplitude after several minutes of exercise. We report a case of secondary hypokalemic PP due to thyrotoxicosis in which the decrease in the CMAP amplitude after exercise dramatically improved after treatment, when a euthyroid state was achieved. The exercise test is a useful electrophysiologic means of monitoring the neuromuscular status of patients with thyrotoxic periodic paralysis prior to, and after treatment of the thyrotoxicosis.

Action Potentials↗
PubMed1992

Unexpected cross-reactivity between myosin and a main immunogenic region (MIR) of the acetylcholine receptor by antisera obtained from myasthenia gravis patients.

Antibodies obtained from the plasma of patients with myasthenia gravis (MG) were found to contain reactivity against both the classic target antigen, the acetylcholine receptor, as well as muscle myosin. This observation was consistent with several previously published reports. However, it was also observed in the present study that much of the dual reactivity contained in MG plasma was due to the ability of individual clonotypic species of anti-receptor antibodies to also bind myosin. Furthermore, the cross-reactivity demonstrated by these antibodies appeared to involve a main immunogenic region of the acetylcholine receptor and an enzymatically important region in the head of the myosin heavy chain. This observation appears to provide new explanations for the epitope-restricted antibody response seen in MG patients.

Amino Acid Sequence↗
PubMed1991

The Bruns-Garland syndrome (diabetic amyotrophy). Revisited 100 years later.

A group of 17 patients had proximal diabetic neuropathy characterized by abrupt onset of asymmetric pain and weakness. Fourteen patients had unilateral onset that later involved the other extremity in 3 days to 8 months. All patients reported stepwise or steady progression during 2 to 18 months that was documented during serial examinations. In 16 patients, both proximal and distal muscles were involved. Sural nerve biopsy specimens demonstrated multifocal variability in nerve fiber density manifesting as nonrandom fiber loss between and within fascicles compared with age-matched controls. These findings demonstrate that patients may have a rapidly evolving course of proximal diabetic neuropathy followed by continued progression for many months and emphasize the overlap between proximal diabetic neuropathies of presumed different types. Our cases and others cast doubt on notions supporting two distinct types of proximal diabetic neuropathies represented by the rapid evolution of asymmetric weakness on an ischemic basis, in contrast to a more slowly progressive condition of metabolic pathogenesis.

Action Potentials↗
PubMed1991

Autosomal recessive distal dystrophy.

We describe five new cases of autosomal recessive distal dystrophy (Miyoshi myopathy) and emphasize the distinctive clinical and laboratory features of this unusual muscular dystrophy. Symptoms began at age 15 to 25, the gastrocnemius muscles were selectively involved, and creatine kinase was elevated more than 10 times normal. The EMG showed abundant brief motor units with numerous fibrillations. Dystrophic features without vacuoles were best seen in the biceps femoris muscle. Asymptomatic creatine kinase elevation was present years prior to the development of weakness. The disorder appears to be inherited in an autosomal recessive pattern. Miyoshi myopathy can be distinguished from other distal muscular dystrophies. We propose a new classification for the distal muscular dystrophies.

Adolescent↗
PubMed1990

Centronuclear myopathy and type-1 hypotrophy without central nuclei. Distinct nosologic entities?

Four infants presented with severe hypotonia, weakness, and hypoventilation or apnea at birth. Their clinical presentations and courses resembled those of the x-linked recessive form of centronuclear myopathy. Histologic examination of their muscle biopsy specimens showed patterns ranging between centronuclear myopathy and type-1 hypotrophy without central nuclei. Regardless of their gender or the appearance of their biopsy specimens, the children all had a poor outcome. The clinical and biopsy findings in these infants suggest that centronuclear myopathy and type-1 hypotrophy without central nuclei do not represent distinct nosologic entities. It seems more likely that the histologic changes represent abnormalities in fiber size distribution and development, which are nonspecific and which reflect a primary defect at one or more sites in the neuraxis.

Biopsy↗
PubMed1990

Recurrent respiratory insufficiency and depressed ventilatory drive complicating mitochondrial myopathies.

Three patients with mitochondrial myopathies and progressive external ophthalmoplegia had repeated episodes of respiratory failure requiring assisted ventilation. Studies in these patients and asymptomatic family members, as well as a sporadic case of Kearns-Sayre syndrome, demonstrated markedly depressed ventilatory drive responses to hypoxia. In 2 patients, there was also decreased drive to hypercapnia. The reduced ventilatory drive appears to be due to an altered neural control system that may cause episodic life-threatening hypoventilation occurring especially in relation to surgery, sedation, or intercurrent infection.

Adult↗
PubMed1989

Chronic inflammatory demyelinating polyradiculoneuropathy. Clinical characteristics, course, and recommendations for diagnostic criteria.

Over a 10-year period, we followed up 60 patients (35 men and 25 women) with chronic inflammatory demyelinating polyradiculoneuropathy. Diagnosis was based on previously outlined criteria. Patients were treated in a uniform manner and the overwhelming majority, 56 (94.9%) of 59 treated patients, initially responded to immunosuppressive therapy. The time for initial improvement was 1.9 +/- 3.6 months while the time to reach a clinical plateau was 6.6 +/- 5.4 months. The course was monophasic in 32 patients (53.3%) and relapsing in 28 (46.6%). Despite the initial responsiveness, only 24 (40%) of 60 patients are in partial or complete remission, receiving no medication. Two patients died. We were unable to identify specific clinical or laboratory features at the time of diagnosis that predicted outcome. Our data analysis, along with previous reports, suggests that chronic inflammatory demyelinating polyradiculoneuropathy may be more heterogeneous than previously emphasized. In this light, we have proposed diagnostic criteria that allow for the heterogeneity but at the same time provide for a more consistent approach to better establish the natural history of this condition.

Biopsy↗
PubMed1989

Myoclonic epilepsy and ragged-red fibers with cytochrome oxidase deficiency: neuropathology, biochemistry, and molecular genetics.

A 36-year-old man with myoclonic epilepsy and ragged-red fibers (MERRF) died after more than 18 years of follow-up study. He was 1 of 3 affected siblings and the offspring of an affected mother, suggesting maternal transmission. At autopsy, there was neuronal loss and gliosis in the dentate nucleus of the cerebellum and in the inferior olivary nucleus. Skeletal muscle showed ragged-red fibers, and paracrystalline inclusions in mitochondria by electron microscopy. Biochemical analysis showed a generalized partial defect of cytochrome c oxidase (COX) in mitochondria isolated from all tissues, including brain, heart, skeletal muscle, kidney, and liver. The Michaelis constant (Km) for cytochrome c was abnormally low, suggesting a defect of the mitochondrially encoded subunit II of COX. Immunological studies (enzyme-linked immunosorbent assay, dot-blot, Western blot, and immunohistochemistry) showed that the holoenzyme was decreased but subunit II was decreased more than the holocomplex or the nuclearly encoded subunit IV. However, Northern and Southern blots showed that the gene for subunit II, as well as the genes for subunits I, III, IV, and VIII, were of normal size and were normally transcribed. A point mutation or a small deletion of mitochondrial DNA, probably affecting the COX-II gene, may be responsible for the COX deficiency in this case of MERRF.

Adolescent↗
PubMed1988

Gastric hypomotility in Duchenne's muscular dystrophy.

In Duchenne's muscular dystrophy, functional impairment of smooth muscle in the gastrointestinal tract can cause acute gastric dilatation and intestinal pseudo-obstruction that may be fatal. We describe a patient with this syndrome who at autopsy had smooth-muscle degeneration of the stomach. To provide objective evidence of functional smooth-muscle impairment in Duchenne's dystrophy, we performed gastric-emptying studies in 11 patients and 11 normal controls, using technetium-99m radionuclide scintigraphy in a test meal of oatmeal. The patients with Duchenne's dystrophy had delayed gastric-emptying times (118.18 +/- 32.21 minutes [mean +/- SEM]) as compared with controls (42.5 +/- 3.4 minutes, P less than 0.01). The cause of the pathological and functional abnormalities we describe in smooth muscle is unknown but may be a deficiency of dystrophin, the recently identified gene product of the Duchenne's muscular dystrophy locus.

Adolescent↗
PubMed1988

Evoked potentials in chronic inflammatory demyelinating polyneuropathy.

Eighteen patients with chronic inflammatory demyelinating polyneuropathy were studied with evoked potentials to assess for evidence of central nervous system demyelination. Both visual and brain-stem auditory evoked responses were obtained, and the results were compared with magnetic resonance imaging (MRI). An evoked potential was abnormal in nine of 18 patients, five of whom had central nervous system evidence of demyelination by MRI. Evoked potentials identified four patients with probable anterior optic pathway involvement that was not demonstrable by MRI. These findings continue to support that chronic inflammatory demyelinating polyneuropathy is associated with a central demyelinating disorder and more importantly emphasize the possibility of a common pathogenic mechanism in central and peripheral nerve demyelination.

Brain Stem↗
PubMed1980

Cranial fasciitis: nodular fasciitis of the head.

An infant was noted at birth to have a lesion over the left coronal suture fixed to both the skin and periosteum, which was identical histologically to nodular fasciitis. This lesion has been described in the literature in various locations, but rarely in the scalp, and not in newborns.

Female↗
PubMedDate not supplied

Congenital ceroid-lipofuscinosis.

A term infant, observed at birth to be microcephalic, developed status epilepticus and died 36 hours later. At autopsy a markedly atrophic brain was found which, by microscopic examination, demonstrated changes consistent with neuronal ceroid-lipofuscinosis. Cerebral lipidosis with microcephaly presenting at birth is extremely rare. Congenital neuronal ceroid-lipofuscinosis is an atypical form of ceroid-lipofuscinosis and should be considered in the differential diagnosis of the microcephalic neonate with seizures.

Astrocytes↗
PubMedDate not supplied

Neonatal nemaline myopathy with abundant intranuclear rods.

A term hypotonic female infant was born to a primigravida mother. The infant required mechanical ventilation from birth until death at 5 weeks of age. An elevated serum creatine kinase of 1300 IU l-1 lead to a quadriceps muscle biopsy at 3 days of age. The biopsy showed numerous intranuclear inclusions on light microscopy. Electron microscopy revealed the inclusions to be rod (nemaline) bodies and were located in 80% of the muscle nuclei. Cytoplasmic rod bodies were also present in 50% of the muscle fibers, often arising from Z discs. The intranuclear rods were more than ten times larger than the cytoplasmic rods. There have been eight reported cases of abundant intranuclear rods in nemaline myopathy: three adult onset; one childhood onset; and four neonatal (including this case). Six of the cases (all of the neonatal and two adult onset) died due to respiratory failure and pneumonia. While intranuclear rods are unusual in nemaline myopathy, they occur in both adult and neonatal cases, and their presence is often associated with a fatal outcome.

Cell Nucleus↗