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Biomedical subjects

W K Engel

Publications and source records attributed to W K Engel.

At least 91 records · Page 5Linked to original sources
PubMed1992

Light and electron microscopic localization of beta-amyloid protein in muscle biopsies of patients with inclusion-body myositis.

In 11 of 11 inclusion-body myositis (IBM) patients, including one hereditary case, vacuolated muscle fibers contained large and multiple small inclusions immunoreactive for beta-amyloid protein (beta AP). All IBM muscle biopsies had characteristic cytoplasmic tubulo-filaments (CTFs) by electron microscopy. None of 14 control muscle biopsies contained the beta AP immunoreactive (IR) inclusions characteristic of IBM. On the light microscopy level, beta AP-IR inclusions colocalized with ubiquitin immunoreactivity. By immunogold electronmicroscopy, beta AP immunoreactivity was localized to a) amorphous, poorly defined structures, b) dense floccular material, c) clusters of loosely packed amyloidlike fibrils 6-8 nm in diameter, and d) poorly defined loose fibrillar structures 6-8 nm in diameter. beta AP immunoreactive structures were often in proximity to CTFs, but CTFs themselves never contained beta AP-IR. Our study provides the first demonstration of beta AP accumulations in abnormal human muscle. This finding suggests that in addition to Alzheimer's disease, Down syndrome, and Dutch-type hereditary cerebrovascular amyloidosis, beta AP may play an important role in the pathogenesis of other diseases, including ones outside the central nervous system, for example, IBM.

Actin Cytoskeleton↗
PubMed1991

Immunolocalization of ubiquitin in muscle biopsies of patients with inclusion body myositis and oculopharyngeal muscular dystrophy.

In 10/10 inclusion body myositis (IBM) patients and 2/2 oculopharyngeal muscular dystrophy (OPMD) patients, vacuolated muscle fibers contained darkly stained ubiquitin (Ub)-immunoreactive cytoplasmic inclusions. By electronmicroscopy, Ub-immunoreactive material was strictly localized to the 15-21 nm pathologic cytoplasmic tubulofilaments (CTFs). None of 18 control muscle biopsies contained the Ub-immunoreactive inclusions that are typical for IBM and OPMD. Thus, (a) finding that CTFs are ubiquitinated places their protein in the Ub-mediated turnover pathway and provides their first molecular marker; (b) easy accessibility, as compared to the central nervous system, of muscle tissue containing ubiquitinated inclusions should be advantageous for biochemical and molecular studies and may provide information important to both systems.

Adolescent↗
PubMed1991

Down-regulation of thyrotropin-releasing hormone (TRH) receptors in spinal cord after transection as revealed by quantitative autoradiography.

The autoradiographic localization of thyrotropin-releasing hormone (TRH) receptors was investigated in the rat spinal cord after transection at the level of T8-T9. The discrete distribution of [3H]-MeTRH binding was measured with a computerized image analyzer at the cervical (C6-C7) and lumbar (L2-L3) level, one week and three weeks after injury. The TRH receptor density was expressed in fmol/mg protein. There was no significant change in the density of TRH receptors below the injury site. In the cervical region, TRH receptor concentration in the dorsal gray matter did not differ from normal controls; in contrast we found a time dependent change in lamina 10 and in the ventral gray, with a significant decrease (25% and 19%, respectively) of TRH receptor binding sites one week after transection and a return to control levels by three weeks. From these data and the known increase of TRH immunoreactivity above a spinal injury, a down-regulation of spinal cord TRH receptors in response to elevated levels of TRH is suggested.

Animals↗
PubMed1990

Abnormalities of aneural and innervated cultured muscle fibers from patients with myotonic atrophy (dystrophy).

Innervation of human muscle cocultured in monolayer with explants of fetal rat spinal cord plus dorsal-root ganglia produces more mature fibers, which show spontaneous, neurogenic (d-tubocurarine-blocked) contractions. On the innervated myotonic atrophy (MA) muscle fibers, 96% of acetylcholinesterase-stained patches were simple, and only 4% appeared as complicated, pretzel-like, more mature-looking structures; on control innervated fibers, 37% of the acetylcholinesterase patches had the mature appearance. The normal trend from multifocal innervation toward unifocal innervation was decreased in innervated MA muscle fibers. Microelectrode studies compared parameters of cultured aneural muscle fibers and cultured innervated-contracting muscle fibers from 7 patients with MA and 10 control patients. The mean resting membrane potentials of the two groups (aneurally cultured MA muscle fibers and innervated-contracting cultured MA muscle fibers) were 8 and 9 mV lower, respectively, than those of their counterpart controls. The mean amplitude of action potentials, the maximum rate of rise of action potentials in innervated MA muscle fibers, and the action potential amplitude in aneural MA muscle fibers were significantly smaller than in corresponding control fibers.

Acetylcholinesterase↗
PubMed1990

Effects of experimental spinal cord transection on substance P receptors: a quantitative autoradiography study.

The autoradiographic localisation of Substance P (SP) receptors was investigated in the rat spinal cord following cordotomy at the thoracic 8-9 level. The binding of [125I]-BH-SP was measured in discrete gray matter structures above (C6-C7 level) and below (L2-L3 level) the injury site, and expressed in fmol/mg protein. There was a statistically significant increase in SP receptor density 1 week after cordotomy in the dorsal horn and in the central canal of lumbar region, in laminae 3-4-5 and also in the ventral horn of cervical spinal cord. Elevated SP receptor density was also noted in cervical ventral horn at 3 weeks after thoracic cordotomy, whereas the increase seen at 1 week was normalized at 3 weeks everywhere else. Since SP concentration has been reported to show a similar localized increase below a spinal transection, the present results are consistent with an up-regulation of SP receptors. A similar direct relationship between SP receptors and SP content appears to occur also in the ventral horn above the injury site.

Animals↗
PubMed1990

Expression of muscle-specific isozymes of phosphorylase and creatine kinase in human muscle fibers cultured aneurally in serum-free, hormonally/chemically enriched medium.

Primary cultures of muscle cells derived from a biopsied adult human skeletal muscle were grown up to 6 weeks in a hormonally/chemically enriched serum-free medium. The expression of muscle-specific isozymes of creatine kinase, glycogen phosphorylase, and phosphoglycerate mutase, indicative of muscle cell maturation, was studied after 1, 4 and 6 weeks of growth. The maturation of muscle fibers cultured in serum-free medium was comparable to that achieved by muscle fibers cultured in medium containing 10% serum and supplemented with growth factors (insulin, epidermal growth factor, and fibroblastic growth factor) and was greater than that achieved in medium containing 10% serum only. Our study demonstrates that adult human muscle can be cultured aneurally for a long period of time in a serum-free medium, and that it can achieve a high degree of maturation. This study provides an important basis for investigations related to: (1) assessment of the influence of individual components of the medium on human muscle maturation in culture; (2) studies of regulation of abnormal gene expression in diseased human muscle cultured in serum-fre medium.

Adult↗
PubMed1990

Paralysis of innervated cultured human muscle fibers affects enzymes differentially.

Increased accumulation of muscle-specific isozyme (MSI) of creatine kinase (CK), lactate dehydrogenase (LDH), glycogen phosphorylase (GP), and phosphoglycerate mutase (PGAM) occurs with development and indicates muscle fiber maturation. The expression of MSIs of those four enzymes is greatly enhanced in innervated-contracting as compared to noninnervated and noncontracting cultured human muscle fibers. We have now studied the effect of contractile activity on developmental accumulation of MSIs in innervated-contracting, innervated-paralyzed (2 microM tetrodotoxin for 30 days), and noninnervated-noncontracting cultured human muscle fibers. Muscle acetylcholinesterase (AChE) and total enzyme activities were also studied under the same conditions. We observed a different dependency on contractile activity between total enzymatic activities of CK, LDH, and AChE, which were substantially reduced after paralysis, and GP and PGAM, which were unchanged. The expression of MSIs of CK, GP, PGAM, and LDH was always significantly increased in innervated as compared to noninnervated fibers. While the expression of MSIs of GP and PGAM was the same in contracting-innervated and paralyzed-innervated muscle fibers, the expression of MSIs of CK and LDH in paralyzed-innervated muscle fibers was very slightly decreased as compared to their contracting-innervated controls. Our studies demonstrate that in human muscle: (1) total enzymatic activities and the expression of MSIs of GP and PGAM are regulated by neuronal effect(s); (2) total enzymatic activities of CK, LDH, and AChE depend mainly on muscle contractile activity; and (3) MSIs of CK and LDH are regulated predominantly by neuronal factors and to a much lesser degree by muscle contractile activity.

Acetylcholinesterase↗
PubMed1990

Immunocytochemical localization of desmin at human neuromuscular junctions.

We localized desmin at human neuromuscular junctions (NMJs) using specific anti-desmin monoclonal and polyclonal antibodies. It was highly concentrated in the postsynaptic domain. It was found in all the NMJs examined. Compared with the area of acetylcholine receptors identified by bound alpha-bungarotoxin, the strong desmin immunoreactivity occupied a slightly larger area and was localized slightly deeper in the muscle fiber, suggesting that desmin might be accumulated within the postsynaptic folds and possibly below the folds. This appears to be the first identification of a protein unrelated to cholinergic transmission accumulated at human NMJs.

Animals↗
PubMed1990

Long-term plasmapheresis therapy is effective and safe in children with chronic relapsing dysimmune polyneuropathy.

Since childhood, two persons, a boy age 12 and a girl age 24 years, with chronic relapsing dysschwannian neuropathy causing severe limb weakness have been maintained on frequent plasmapheresis for more than 8-1/2 and 9 years respectively. They are totally dependent on it. Onset of disease was at ages 2-1/2 and 9 years. Both patients had had major relapses, some requiring ventilatory support, despite continued maximally-tolerated pharmacologic antidysimmune treatment. Plasmapheresis was started in August 1980 and December 1979, respectively. The current schedule is a set of 3 in one week at eight-week intervals for patient 1 and twice every 7-10 days for patient 2. They have had more than 330 and more than 1,100 phereses respectively. Since beginning phereses, neither has had a major relapse, and both are functional in their daily life as students, although with slight and moderate residual weakness respectively. The dependence of these 2 patients on regular pheresis for the last 8-1/2 and 9 years proves its efficacy and safety in children. Long-term maintenance pheresis may be beneficial in patients with other forms of chronic dysimmune neuropathy.

Adult↗
PubMed1989

Nuclear inclusions in innervated cultured muscle fibers from patients with oculopharyngeal muscular dystrophy.

We established monolayer muscle fiber cultures from muscle biopsies of 3 patients with oculopharyngeal muscular dystrophy (OPMD) who had characteristic intranuclear inclusions (INI-A) in their muscle fibers. Aneural cultures had normal morphology, except for a few muscle fibers that contained small vacuoles. Innervated cultures had large cytoplasmic vacuoles in a number of muscle fibers. Those muscle fibers were breaking easily, and could not be maintained longer than 2 months. Electron microscopy showed unusual intranuclear inclusions (INI-B) not previously reported in aneurally cultured muscle fibers of OPMD or in any normal or disease-control aneural or innervated cultured human muscle fibers. They resembled, but were not identical to, the INI-A, and they occurred in both the cultured fibers and the original muscle biopsies of all 3 patients. Our study demonstrate that (1) nuclear inclusions in OPMD reflect an intrinsic genetic defect; and (2) neuronal influence, advanced maturation, or both, seem to be essential for their induction in muscle fibers.

Aged↗
PubMed1988

Asynchronous regulation of muscle specific isozymes of creatine kinase, glycogen phosphorylase, lactic dehydrogenase and phosphoglycerate mutase in innervated and non-innervated cultured human muscle.

Expression of muscle specific isozymes (MSIs) of creatine kinase (CK, EC 2.7.3.2), glycogen phosphorylase (GP, EC 2.4.1.1), lactate dehydrogenase (LDH, EC 1.1.1.27) and phosphoglycerate mutase (PGAM, EC 2.7.5.3) was studied both in cultured human muscle fibers which had been innervated (InnCHMFs) for 20-83 days, and in their non-innervated (non-InnCHMFs) sister control. In non-InnCHMFs, the MSI of PGAM was never detected, and there was no change in the expression of the MSI of CK during the entire period examined; the expression of MSIs of LDH and GP showed linear increase during the entire period of growth. The expression of MSIs of all 4 enzymes was significantly enhanced in InnCHMFs as compared to non-innervated control. The expression of MSIs of GP and PGAM, and to a lesser degree of LDH increased significantly in correlation with the duration of innervation; the MSI of CK increased linearly only up to 54 days of innervation and plateaued afterward. This study demonstrates: (1) innervation of cultured human muscle fibers by fetal rat spinal cord exerts a time-related maturational influence on their cellular isoenzymatic pattern; (2) to achieve induction and characteristic time-related expression of various MSIs, the requirements for neuronal influences seem to differ.

Bisphosphoglycerate Mutase↗