Fiber-type specific caffeine sensitivities in normal human skinned muscle fibers.

Caffeine sensitivity was studied in chemically skinned muscle fibers from vastus lateralis muscle obtained by biopsy during reconstructive knee surgery from 15 otherwise healthy young individuals. Muscle fiber type was determined by contracture occurring in strontium (slow-oxidative, type I fiber) or calcium (both type I and type II, fast glycolytic fiber) solutions and in several fibers after contracture testing by ATPase enzyme histochemistry. Caffeine sensitivity (mean +/- SD), defined as the threshold concentration inducing more than 10% of the maximal tension obtained with a calcium 3 x 10(-5) mM solution was 2.

Amyotrophic lateral sclerosis. Recent advances in pathogenesis and therapeutic trials.

We reviewed the current status of pathogenesis and therapeutic trials in amyotrophic lateral sclerosis (ALS). Clinical studies have identified several rare but definable causes for apparent ALS. Certain clinical features previously considered unlikely to occur in ALS are found on careful examination.

Thyrotropin-releasing hormone (TRH) in murine motor neuron disease (the wobbler mouse).

Clinical benefits of thyrotropin-releasing hormone (TRH) were tested in wobbler mice, an animal model of motor neuron disease. After the disease was clinically recognized at 3-4 weeks, the animals were divided into two groups, each group consisting of 5 pairs of wobbler mice and normal littermates. TRH (50 mg/kg) and normal saline (NS) were injected intraperitoneally daily, 6 times per week for 9 weeks, in a double-blind study.

Inclusion body myositis presenting as treatment-resistant polymyositis.

Inclusion body myositis (IBM) has been viewed as a distinct and rare form of inflammatory myopathy. Previously reported findings from series of IBM patients have suggested that clinical and pathologic features are present which readily distinguish it from idiopathic polymyositis. We report 4 cases of IBM presenting clinically and pathologically as polymyositis, each of which was refractory to therapy.

Chloroquine neuromyotoxicity. Clinical and pathologic perspective.

Six cases of toxic myopathy and/or neuropathy with chloroquine and/or hydroxychloroquine therapy are described. Two patients had unique clinical and pathologic evidence of cardiomyopathy secondary to chloroquine or hydroxychloroquine therapy. One patient had polyneuropathy secondary to chloroquine toxicity.

Vacuolated anterior horn cells in wobbler mouse motor neuron disease: peripheral axons and regenerative capacity.

We investigated whether vacuolated cervical anterior horn cells of the wobbler mouse maintain axons to the periphery, and if these morphologically abnormal neurons are capable of supporting axonal regeneration. Using retrograde axonal transport, we applied horseradish peroxidase (HRP) to peripheral nerves or muscles and with electron microscopy sought evidence for perikaryal labeling in vacuolated neurons in 23 wobbler mice. When HRP was injected into forelimb muscles, 12 of 36 vacuolated neurons became positively labeled indicating that these neurons have axons in continuity with the periphery.

Respiratory insufficiency in adult-onset acid maltase deficiency.

Although the adult form of acid maltase deficiency is characterized by weakness of the limb girdle muscles, weakness of the respiratory muscles out of proportion to that of the limb muscles may make the diagnosis less obvious. We present four patients aged 35 to 57 with respiratory muscle weakness associated with signs of cor pulmonale and symptoms of alveolar hypoventilation. Each had symptoms of fatigue, hypersomnolence, morning headache, and orthopnea, the cause of which was misdiagnosed.

Amyotrophic lateral sclerosis: effects of acute intravenous and chronic subcutaneous administration of thyrotropin-releasing hormone in controlled trials.

We performed double-blind crossover trials to assess the effects of thyrotropin-releasing hormone (TRH) on amyotrophic lateral sclerosis patients. For acute intravenous trials, 500 mg TRH or placebo with norepinephrine was given at 1-week intervals (16 patients). CSF TRH concentration increased, and clinical side effects appeared with TRH.

Impaired slow axonal transport in wobbler mouse motor neuron disease.

We studied slow axonal transport and morphometry of forelimb axons in wobbler mice and controls. In wobbler mice, the total radioactivity migrating with the slow transport was decreased by 50%. The velocity of transport also appeared to be reduced; 15 days following administration of a radioisotope, polypeptides migrating with slow component a of transport did not form a peak and remained mostly 2 mm from the spinal cord, while in controls slow component a was distributed as a peak which was located 4 mm from the cord.

Motor neuropathy associated with a facilitating myasthenic syndrome.

We report a patient with progressive muscle weakness, areflexia, and no sensory loss. Electromyography revealed normal sensory nerve conductions, mild slowing of motor nerve conduction velocities, low amplitude compound muscle action potentials, a neuromuscular transmission defect characterized by prominent facilitation, and diffuse fibrillation potentials. Muscle biopsies showed acute denervation atrophy, and at autopsy, there was anterior horn cell loss and gliosis in the spinal cord.

Motor neuron disease and adult hexosaminidase A deficiency in two families: evidence for multisystem degeneration.

We studied three patients from two unrelated families with adult hexosaminidase A deficiency. A 30-year-old, non-Jewish proband in the first family had juvenile amyotrophic lateral sclerosis that evolved to mild dementia, ataxia, and axonal (neuronal) motor-sensory peripheral neuropathy. A 36-year-old Jewish proband in the second family had "pure" spinal muscular atrophy.

Axonal regeneration in wobbler motor neuron disease: quantitative histologic and axonal transport studies.

The regenerative capacity of the cervical anterior horn cells was studied at 4 and 7 days following forelimb nerve crush in 19 wobbler mice and 18 normal littermates. Quantitative histologic and radiolabeled axonal transport techniques showed that the axotomized neurons of the wobbler mouse supported active axonal elongation. However, the average axon outgrowth rate determined by histologic technique was diminished by 25% and the fastest axon outgrowth rate determined by axonal transport technique was also decreased by 30% in wobbler mice as compared to controls.

Chronic progressive external ophthalmoplegia (CPEO): clinical, morphologic, and biochemical studies.

We studied skeletal muscles from eight chronic progressive external ophthalmoplegia patients with ragged-red fibers (group A), five CPEO patients without ragged-red fibers (group B), and five controls. The EM morphometric fraction of structurally abnormal mitochondria was increased in group A, and there was a similarly increased fraction of normal-appearing mitochondria in group B. State 3 respiration and uncoupled respiration were severely decreased in both groups.

Murine motor neuron disease (the wobbler mouse): degeneration and regeneration of the lower motor neuron.

The study of the temporospatial pattern of lower motor neuronal generation in the wr/wr mouse demonstrated that the pathological changes started in the neuronal perikaryon in the spinal cord. Thus the wr/wr mouse suffers from a primary motor neuronopathy. Axonal pathology predominated at the level of the ventral root and suggested a focal proximal axonopathy.

Adult-onset acid maltase deficiency presenting as diaphragmatic paralysis.

A 51-year-old man presented with a six-year history of gradually progressive exertional dyspnea. His complaint was attributed to increasing age, but evaluation finally led to a diagnosis of diaphragmatic paralysis. Neurological examination disclosed only minimal evidence of weakness of limb muscles.

Focal EEG abnormalities in Heidenhain's variant of Jakob-Creutzfeldt disease.

Serial EEGs obtained during a six-week period from a patient with Heidenhain's variant of Jakob-Creutzfeldt disease demonstrated periodic complexes confined to the occipital regions that at no time became generalized. The focal character of the discharges correlated with the site of maximal disease in the occipital cortex, suggesting that cortical damage is a necessary substrate for the production of periodic complexes in Jakob-Creutzfeldt disease.

Malignant lymphoma of the central nervous system: a case of primary spinal intramedullary involvement.

Primary involvement of the spinal cord in malignant lymphoma is rare. Clinical and pathologic features of a case of malignant lymphoma initially involving the spinal cord and subsequently one cerebral hemisphere are reported and the medical literature reviewed. If malignant lymphoma of the central nervous system is diagnosed by means of brain biopsy examination, radiotherapy of any coexisting intramedullary spinal cord lesion of undetermined cause should be considered.

Perineurioma as the cause of localized hypertrophic neuropathy.

Clinical, electrodiagnostic, and morphological studies were performed on three patients with localized hypertrophic neuropathy (LHN). LHN is characterized clinically by slowly progressive motor mononeuropathy without significant pain or numbness. Nerve conduction studies and needle electrode examination show severe focal motor and sensory axonal loss.

Mucormycosis presenting as positional nystagmus and hydrocephalus. Case report.

A case of mucormycosis presenting with signs of positional nystagmus and obstructive hydrocephalus is described. The authors believe that this presentation of Mucor is unique.