Biomedical subjects
Publications and source records attributed to S P Ringel.
We report a kindred manifesting clinical features and muscle biopsy findings of inclusion body myositis (IBM). In this family, multiple members were affected in two generations with direct male-to-male and female-to-male transmission. This is the first reported instance of autosomal dominant inheritance in IBM, which usually occurs sporadically or, rarely, may be transmitted as an autosomal recessive disorder.
Muscle function is often severely impaired in peripheral arterial disease (PAD), but the effects of repeated ischemic events upon nerve and muscle are incompletely characterized. We performed comprehensive electrophysiologic studies and skeletal muscle histologic analysis in six patients with unilateral PAD and five control subjects matched for age and activity level. In the PAD patients, all ischemic legs showed both electrophysiologic and histologic evidence of chronic partial denervation-reinnervation restricted to distal muscles. Two of the PAD patients had evidence of milder distal denervation in the nonischemic legs. Two of the controls had denervation in at least one leg, but in each case electrophysiologic findings were pathognomonic of L-5 and S-1 radiculopathies. All other control legs and nonischemic legs were normal. These results suggest that recurrent ischemia associated with PAD may cause muscle denervation, which may be one of the mechanisms responsible for decreased exercise performance in these patients.
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The American Medical Association Physician Masterfile for 1990 contains 13,705 physicians who consider neurology their primary, secondary, or tertiary specialty. Of these, 7,036 are board certified and 10,065 designated neurology as their primary specialty. Although there has been a steady increase in the number of women, the vast majority of neurologists are men and less than 50 years old. Two-thirds provide direct patient care as their major activity and 15% are in training. There are almost as many neurologists employed by hospitals, medical schools, and government entities (40%) as there are working alone or in group practice (48%). The actual number of neurologists is compared with earlier projections of neurology needs for 1990. Since forecasts, in the absence of more detailed information, can become the reality of public policy decisions, neurologists will need to become increasingly informed about the many unique benefits they provide to their patients.
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The purpose of this study was to observe fiber area changes that might occur in the same subject from two opposing resistance-exercise training regimes isolating the quadriceps muscle group. Twelve college-age men divided into two groups participated in each of two 7.5-week regimens; one performed a muscular strength program (high-resistance, low-repetition) 4 days a week on a resistance-exercise apparatus, while the other performed a muscular endurance (low-resistance, high-repetition) program. After a 5.5-week hiatus, the groups changed regimens for the second 7.5 weeks. Closed-needle biopsies of the dominant vastus lateralis and isokinetic dynamometer evaluations were made before and at the end of each training period. The muscle samples were analyzed for area changes. In both groups the initial exercise stimulus, whether for strength or endurance, increased the area of fibers of all three major types (I, IIA, and IIB). Subjects doing strength exercises as their second treatment showed a further increase in the area of type I and IIB fibers, whereas those doing endurance exercises showed a decrease in all fiber types. From the first to the last biopsy all fiber areas were decreased (P less than 0.05) in the control-strength-endurance group and increased (P less than 0.05) in the control-endurance-strength group. These results suggested that endurance exercise preceding strength exercise in an isolated muscle group maximized fiber area adaptations to exercise stress. Consideration should thus be given in exercise and rehabilitation programs to the muscle cellular adaptations evidenced in different orders of training, particularly if muscular strength is considered important.
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We initially surveyed the practice patterns of 24 private sector neurologists in Colorado between June and September, 1985, having chosen representative practices from each of 4 practice types (solo [6], nonsolo single discipline [11], nonsolo multispecialty [4], and nonsolo HMO [3]) and from both urban (14) and rural (10) practice locations. Among 2,373 consecutive new patient visits initially surveyed, we reexamined 2,359 (99%) charts 1 year later to investigate patterns of principal care. We defined principal care as 2 or more follow-up visits in the year following the initial office visit. One-fifth of initial visits received principal care, and the mean number of follow-up visits per year among those receiving principal care was 4 (range, 2 to 32 visits). The best indicators of principal care were Medicare coverage, a classic neurologic diagnosis (seizure, stroke), rural practice location, and solo neurology practice. The best indicators of consultative care were self-pay coverage, a diagnosis of musculoskeletal, psychiatric, or pain disorder, urban practice location, and HMO neurology practice. Age, sex, race, and type of referring physician were unimportant in determining subsequent principal care. Projections of future manpower needs must reflect both consultative as well as principal care services provided by neurologists, as well as the cost-effectiveness of such care.
This study, a retrospective review of 165 patients with myasthenia gravis, compares the course of the disease for patients with onset before 50 and at or after 50. There were no significant differences between age groups for presenting symptoms, but more of the older patients had progressed to severe disease. More of the younger than the older patients were in remission or were asymptomatic on medication at the last visit. Sixty-two percent of those treated with steroids developed complications, with a larger portion of these being in the older group. Cataracts, infection, and bone changes were particularly significant for the older population. Complications of azathioprine treatment and plasmapheresis were less common. Thymoma was more common in the older population; these patients did no worse than the population as a whole. Sixty-five percent of our patients have undergone thymectomy, most by a modified transsternal approach. A much larger portion of those who underwent thymectomy were in remission at the last visit than those who did not.
In examining the incidence and progression of electrocardiographic abnormalities in 45 patients with myotonic dystrophy, 26 (58%) of whom at entry had at least 1 electrocardiographic abnormality, we found conduction abnormalities in 17 (38%). In 21 patients (47%), new abnormalities developed during follow-up (mean, 4.6 years). The overall incidence of electrocardiographic abnormalities increased to 78%, and the incidence of conduction defects increased to 62%. Second-degree or complete atrioventricular block did not develop in any of the patients. Pseudoinfarction patterns were common at entry and during follow-up and were not correlated with evidence of clinical coronary artery disease. There was no correlation between the presence of electrocardiographic abnormalities and apparent disease severity.
While sudden monocular blindness and occlusion of the central retinal artery associated with acute thrombosis of the internal carotid artery are well reported, concurrent unilateral ophthalmoparesis is not. We studied 3 adult men who did not have other major signs of vascular disease but who exhibited the complete syndrome. The initial paresis of the oculomotor, trochlear, and abducens nerves varied in each individual and slowly cleared over days to weeks in all, but vision did not return in any. Each had mild-to-moderate signs of hemispheric dysfunction. In each, the thrombus extended from the origin of the internal carotid to its intracranial bifurcation into the anterior and middle cerebral arteries. It also occluded the proximal one-half to two-thirds of the ophthalmic artery. None had evidence of vasculitis or compromise of the posterior circulation.
We prepared RNA probes from cloned segments of human and murine enteroviruses (EVs) for in situ hybridization of skeletal muscle biopsies from patients with dermatomyositis (DM), polymyositis, other inflammatory myopathies, and noninflammatory muscle diseases, and from normal control subjects. A probe derived from Theiler's murine encephalomyelitis virus (TMEV) detected viral RNA within mononuclear cells of the interstitial connective tissue in 3 of 5 patients with adult-onset DM. None of these patients showed positive hybridization to probes derived from human EVs (poliovirus type 1 and Coxsackie virus B3) applied to subjacent sections of the same biopsies. The remaining 2 adult DM patients, 4 patients with childhood-onset DM, and 24 non-DM patients did not react with either TMEV or human enterovirus probes. Histochemical stains for esterase and immunoperoxidase stains for Mac-1 antigen in the 3 DM patients who reacted positively revealed positive cells in the same distribution as, but in far greater number than, those positive by in situ hybridization. Immunoperoxidase staining for HLA-DR antigens revealed positive cells in the same distribution and number as were seen with the TMEV probe. We conclude that an EV-like agent, more closely related to TMEV than to human EVs, may be associated with DM and that this agent is probably localized within muscle macrophages that express class II major histocompatibility complex antigens.
The complex glycerol kinase deficiency (GKD) syndrome is an X-linked recessive genetic disorder. The syndrome often includes a myopathy that is similar histologically to Duchenne muscular dystrophy (DMD). The glycerol kinase (GK) locus is in the Xp21 region in the midportion of the short arm of the X chromosome and is in close proximity to the DMD locus. We have investigated GK activity and subcellular distribution of muscle GK in DMD patients and in a patient with the complex GKD syndrome presenting with myopathy. We found no abnormality of muscle GK specific activity or subcellular distribution in DMD. In the patient with the complex GKD syndrome the specific activity and kinetics of muscle GK were normal, but the subcellular distribution of muscle GK was altered. Liver GK had less than 10% of normal activity and showed markedly altered kinetics. These findings indicate that there is no abnormality of muscle GK activity in DMD muscle. Furthermore, the normal GK activity in an individual with the complex GKD syndrome suggests that muscle and liver GK are genetically distinct. These findings support the concept that the complex GKD syndrome results from small deletions that affect closely linked but separate loci for DMD, GK and adrenal hypoplasia.
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