Biomedical subjects
Publications and source records attributed to F J Samaha.
A 34-year-old man presented with progressive neurologic deterioration though clinically to be multiple sclerosis. At autopsy, the cerebral white matter, deep gray matter, and brain stem were diffusely infiltrated with cells characteristic of oligodendrocytes. Gliomatosis cerebri consisting predominantly of oligodendroglia is rare.
We have established the first prospective, collaborative study of spinal muscular atrophy, the second most common neuromuscular disease of childhood. One hundred and forty-one patients have been evaluated on at least four occasions over a 3-year period. The patients have been grouped by age of onset, as well as by function at the time of initial evaluation. The muscle strength of 96 patients aged 5 years or older was evaluated at 6-month intervals using a fixed myometry system. The new observations made are: (1) The present classification schema is not valid; for example, 49 patients with onset of weakness before 6 months of age (type I or Werdnig-Hoffmann disease), whose life span is said to be only 2 to 4 years, participated in the study and are 4 months to 31 years of age. (2) Thirty-seven patients were evaluated over an 18-month period. None lost strength during this time but four lost function. Although the period of observation was short, the results suggest that the loss of function in patients with spinal muscular atrophy might be explained by a process other than cell death that allows patient strength to be maintained and simultaneously prevents the motor unit from achieving its normal adult potential.
BACKGROUND: Thymectomy has continued to gain acceptance as definitive treatment for myasthenia gravis. Because of the nature of thymic embryology with scattered rests throughout the anterior mediastinum, we advocate a transsternal thymectomy with extended anterior mediastinal dissection. METHODS: A series of 48 patients with myasthenia gravis treated by thymectomy between 1979 and 1991 were reviewed. RESULTS: The mean length of duration of disease from onset to operation was 48.7 +/- 11.3 months, and the mean length of follow-up was 51.6 +/- 6.5 months. The operation was associated with a 21% morbidity rate (4% major morbidity) with no deaths. Forty-five patients (94%) have improved, requiring decreased medication. The overall drug-free remission rate was 42%. Of the 20 patients in remission, three had thymomas and four had hyperplastic glands. All of the patients who achieved drug-free remission were classified as Osserman's I or II. CONCLUSIONS: An aggressive surgical approach to myasthenia gravis can result in a high percentage of overall improvements and drug-free remissions. The best results are achieved in patients with lower-stage disease. Therefore transsternal extended thymectomy for myasthenia gravis appears to be the procedure of choice and should be advocated as soon as the diagnosis is made and the patient stabilized.
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A series of 27 patients with generalized myasthenia gravis is presented. All patients were treated by a sternal split and extended thymectomy and radical mediastinal dissection. The overall drug-free remission rate was 63%, although three additional patients are likely to achieve drug-free remission in the near future, with the total drug-free remission rate then being 74%. Of the remaining patients, all but three improved and require decreased medication, for an improvement rate of approximately 90%. One patient who has not improved had an invasive malignant thymoma. Drug-free remission was achieved in 46% of the male patients and in 82% of the female patients despite that the mean duration of disease was greater than 3.5 years. There was one serious complication, that of sterile sternal dehiscence. There was no mortality. The results suggest that an aggressive, radical surgical approach to myasthenia gravis, even in a group of patients considered somewhat less favorable because of a relatively long duration of disease, can result in a high percentage of drug-free remissions. Radical surgery for myasthenia gravis appears to be the treatment of choice, with medical therapy being reserved for those patients who are not likely to survive operation.
Muscle cells were cultured from six patients with Duchenne muscular dystrophy and nine normal subjects. Protein and myosin content and pyruvate kinase (PK) activity were similar in normal and Duchenne muscular dystrophy cultures. Creatine kinase (CK) activity was lower in Duchenne muscular dystrophy cultures and the isoenzyme distribution indicated MB-CK was significantly lower, while BB-CK was significantly higher in later Duchenne muscular dystrophy cultures. This abnormal isoenzyme pattern suggested aberrant or impaired maturation of Duchenne muscular dystrophy myotubes in vitro.
Human muscle sarcoplasmic reticulum (SR) yields three major protein bands. The percent distribution of the mean values of the bands from 15 normal human muscles was 55.4, 14.6, and 30.0 for the 100, 55, and 45-kDa mass proteins, respectively. A mean distribution similar to that in normal muscle SR was found in preparations from 7 patients with polymyositis and from 7 patients with myotonic dystrophy. In 12 preparations from patients with Duchenne dystrophy, the protein distribution differed from that of preparations from normal muscle. The 100-kDa mass protein band was decreased, whereas the 55- and 45-kDa mass bands were increased. Protease inhibitors pepstatin A, antipain, and leupeptin, as well as ethyleneglycol-bis(aminoethyl ether)-N,N,N',N'-tetraacetic acid or ethylenediaminetetraacetic acid, significantly reduced this change. However, some of the changes cannot be prevented by the addition of inhibitors and must be expressed in vivo. Neither protease inhibitors nor chelators affected SR preparations from normal muscle. We found a five- to ten-fold increase in calcium-activated neutral protease activity in Duchenne dystrophic muscles that degraded the calcium-adenosinetriphosphatase of SR. The active protease was identified as the cytoplasmic calpain II. The increased activity in Duchenne muscles may explain many reported abnormalities.
Myosin light chains were isolated from cat gastrocnemius and soleus muscles rendered paraplegic for 1 year and from the vastus lateralis of six patients with Duchenne muscular dystrophy. Despite the altered pattern of function of these muscles, no alterations were noted in the type or relative proportion of these myosin light chains when compared to control muscles.
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