When thymocytes are stimulated they generate reactive oxygen species, which under appropriate conditions produce chemiluminescence (CL). The reactions occur near the cell surface. Since genetically determined muscular dystrophies are currently considered "membrane diseases," we tested the CL of thymocytes from dystrophic hamsters, strain BIO 14.6, in comparison with control animals of the Rb-strain. CL of 33 x 10(6) thymocytes each was monitored in a liquid scintillation counter at 32 C. Dystrophic cells stimulated with concanavalin A (Con A) reached only 60% of the normal peak CL. When stimulated with the calcium ionophore A23187, dystrophic cells exhibited only 40% of the peak CL of control cells. The thymus weight of dystrophic hamsters was significantly reduced. It is not known yet whether these alterations of the thymus are secondary to extrathymic factors or whether they are intrinsic to the thymocyte. If the latter is true, it would be an indication that the genetic defect of dystrophic hamsters is also expressed in the thymus.

Animals↗

PubMedDate not supplied

Proline incorporation by cultured skin fibroblasts from patients with duchenne muscular dystrophy.

The incorporation of proline by cultured skin fibroblasts derived from normal individuals and patients with Duchenne muscular dystrophy (DMD) was analyzed by SDS-gel electrophoresis combined with a double-labeling procedure [Pediatr. Res., 12: 887 (1978)]. DMD fibroblasts showed increased proline incorporation into protein of approximately 130 000 daltons which could be degraded partially by collagenase. This difference was observed only at 7 days after seeding, and may be due to slight differences in growth rate as comparison of cells harvested at 2 and 7 days indicated that increased proline incorporation into high molecular weight protein was associated with day 7 cells, whether normal or DMD. During 14 days in culture normal and DMD strains did not differ in protein content, doubling time or incorporation of [3H]leucine and [14C]proline into cellular protein, although the ratio of [14C]proline to [3H]leucine incorporated was greater for DMD fibroblasts at 7 days. Incorporation of [14C]proline and [3H]leucine into extracellular proteins was greater in DMD fibroblast cultures. These subtle differences support the hypothesis that the DMD gene is expressed in fibroblasts.

Cell Differentiation↗

PubMedDate not supplied

56K fibroblast protein not specific for Duchenne muscular dystrophy but for skin biopsy site.

Recently, we reported the detection by two-dimensional gel electrophoresis of a 56,000 (56K)-molecular weight polypeptide that was present in cultured skin fibroblasts from normal males but was not detectable in fibroblasts from Duchenne muscular dystrophy (DMD) patients. Since then we have established that the 56K polypeptide is not present in skin fibroblasts from normal females, DMD carrier females, or in normal male fibroblasts obtained from sources other than the Repository for Mutant Human Cell Strains, Montreal. Further inquiry has led to the discovery that all the normal male fibroblast cultures obtained from the Montreal repository had been established from preputial skin. Fibroblast cultures from DMD patients, DMD carriers, as well as other normal individuals, had been derived from non-genital skin biopsies. Thus, the absence of the 56K polypeptide is not specific for DMD, but rather is related to the site of skin biopsy.

Biopsy↗

PubMedDate not supplied

Analysis of deletions in DNA from patients with Becker and Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic disorder for which the biochemical defect is as yet unknown. Recently, two cloned segments of human X-chromosome DNA have been described which detect structural alterations within or near the genetic locus responsible for the disorder. Both of these cloned segments were described as tightly linked to the locus and were capable of detecting deletions in the DNA of boys affected with DMD. In an attempt to determine more precisely the occurrence of these deletions within a large population of DMD patients and the accuracy of one of the segments, DXS164 (pERT87), in determining the inheritance of the DMD X chromosome, the subclones 1, 8 and 15 were made available to many investigators throughout the world. Here we describe the combined results of more than 20 research laboratories with respect to the occurrence of deletions at the DXS164 locus in DNA samples isolated from patients with DMD and Becker muscular dystrophy (BMD). The results indicate that the DXS164 locus apparently recombines with DMD 5% of the time, but is probably located between independent sites of mutation which yield DMD. The breakpoints of some deletions are delineated within the DXS164 locus, and it is evident that the deletions at the DMD locus are frequent and extremely large.

Chromosome Deletion↗

PubMedDate not supplied

A 63-kDa protein with androgen-binding activity is not from the androgen receptor.

We have found a new protein in the heart of rat and mice that can be selectively and covalently labelled with the synthetic androgen analog mibolerone. Binding is specific as it can be displaced by excess radioinert ligand. The protein is prominently expressed in liver, kidney, and heart, but not in skeletal muscle. It is water soluble and found in the cytosol. Under denaturing conditions it has a molecular weight of 63,000 and appears on two-dimensional gels with an isoelectric point of 6.3. The protein's affinity for androgen is lower than that of the androgen receptor and it is about 100-fold more abundant than the receptor in the heart. Expression of the protein is not induced by androgen. The presence of this protein in testicular feminization (tfm) mice with a genetical defect of the androgen receptor rules out that it is the androgen receptor or a portion thereof. The biological role of this protein is not yet known.

Animals↗