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G B Hartwig

Publications and source records attributed to G B Hartwig.

9 recordsLinked to original sources
PubMed1983

Radionuclide angiocardiographic analysis of myocardial function in myotonic muscular dystrophy.

Using radionuclide angiocardiography, we studied cardiac function in 10 men with myotonic muscular dystrophy who had no cardiac symptoms and were less than 50 years of age, comparing resting and exercise performance of the heart. Nine of 10 patients had an abnormality of myocardial function. The interaction of exercise-induced cardiomyopathy with conduction system abnormalities may be important in sudden cardiac dysfunction in patients with myotonic dystrophy.

Adult↗
PubMed1981

Patients with myotonic dystrophy, a possible segmental progeroid syndrome, and Duchenne muscular dystrophy have fibroblasts with normal limits for in vitro lifespan and growth characteristics.

Myotonic dystrophy (MyD) has been suggested to be a segmental progeroid syndrome in man, as this syndrome has some clinical manifestations of premature aging. Fibroblasts from patients with other progeroid syndromes have been shown to have diminished in vitro lifespans or growth characteristics; therefore, it was of interest to study cellular senescence in fibroblasts from patients with MyD. Fibroblast cultures from patients with Duchenne muscular dystrophy (DMD) were used as additional controls, as premature aging is not associated with this genetic disorder. Primary skin fibroblast cultures obtained from patients with MyD or DMD and from age-sex matched controls were grown in DMEM plus 10% FBS. The in vitro lifespan was determined by either a 1:4 split ratio or with a constant initial inoculum of 1 times 10(4) cells/cm2, followed by determination of the final density at weekly intervals. Our results demonstrate that there is no difference in the limits of the in vitro lifespan for either the MyD or DMD fibroblast strains compared to the controls. Likewise, no difference could be detected in the growth characteristics of these cells. The only observable difference was that the pooled age-matched controls and MyD cultures had a shorter in vitro lifespan than the DMD group and their pooled controls, a finding expected because of the age of the patients in each group. Unlike the other progeroid syndromes, MyD fibroblasts have normal limits for in vitro lifespan. MyD is probably not closely related to the other premature aging syndromes, although there is an increasing phenotypic expression as a function of age.

Adolescent↗
PubMed1979

Debrancher deficiency: neuromuscular disorder in 5 adults.

Five patients, 4 men and 1 woman, had adult-onset and slowly progressive weakness. There was distal wasting in 2, hepatomegaly in 3, and congestive heart failure in 2. Electromyography showed a mixed pattern with abundant fibrillations. Serum creatine phosphokinase was increased 5- to 45-fold. Blood glucose failed to respond to epinephrine or glucagon, and venous lactate did not rise after ischemic exercise. Muscle biopsy showed vacuolar myopathy affecting both fiber types. By electron microscopy the vacuoles corresponded to large pools of glycogen not limited by a membrane. Glycogen concentration was 3 to 5 times normal in muscle and 7 to 21 times normal in erythrocytes. In the presence of iodine, muscle glycogen showed a spectrum characteristic of phosphorylase-limit-dextrin. Debrancher activity was measured by a spectrophotometric assay and by a radioactive reverse reaction. The activity was lacking in muscle and erythrocytes of 4 patients according to both assays; in 1 patient the reverse reaction was not impaired. Though previously reported in only 5 patients, debrancher deficiency myopathy may not be rare and should be considered in the differential diagnosis of adult-onset hereditary myopathies.

Adolescent↗
PubMed1978

Biochemical relationships between muscle and erythrocyte membrane. Interpretations with respect to Duchenne muscular dystrophy.

Whether Duchenne muscular dystrophy (DMD) is a disease of primary myogenic, secondary neuropathic, vascular or membrane etiology is the subject of some debate. Using the erythrocyte membrane as a biopsy tissue we present biochemical data that support the possibility of a defect in myosin as the genetic defect in DMD. Peptide analysis of hydrolyzed erythrocyte spectrin supports previous data demonstrating an alteration in DMD spectrin. The biochemical and biophysical similarities between spectrin and myosin can be tested with available technology. The hypothesis that a defect in myosin may be responsible for DMD is attractive because it is testable.

Erythrocyte Membrane↗
PubMed1977

Pedigree testing in Duchenne muscular dystrophy.

Female relatives of 41 Duchenne muscular dystrophy proband cases were studied with a panel of carrier-detection tests. A total of 277 relatives were tested in order to determine which mothers had affected sons as a result of new mutation. In 39 of 41 pedigrees the data demonstrate that a mutation cannot be postulated; the 2 megative pedigrees were inadequately tested. Our data suggest that all mothers of affected sons should be considered genetic carriers (heterozygotes) until proved otherwise. Our findings also raise questions concerning what mechanisms skew the indirect statistical estimates of mutation that are in common use.

Adolescent↗