R. Yarom

Down's syndrome: abnormal neuromuscular junction in tongue of transgenic mice with elevated levels of human Cu/Zn-superoxide dismutase

To investigate the possible involvement of Cu/Zn-superoxide dismutase (CuZnSOD) gene dosage in the neuropathological symptoms of Downs syndrome, we analyzed the tongue muscle of transgenic mice that express elevated levels of human CuZnSOD. The tongue neuromuscular junctions (NMJ) in the transgenic animals exhibited significant pathological changes, namely, withdrawal and destruction of some terminal axons and the development of multiple small terminals. The ratio of terminal axon area to postsynaptic membrane decreased, and secondary folds were often complex and hyperplastic. The morphological changes in the transgenic NMJ were similar to those previously seen in muscles of aging mice and rats as well as in tongue muscle of patients with Downs syndrome. The findings suggest that CuZnSOD gene dosage is involved in the pathological abnormalities of tongue NMJ observed in Downs syndrome patients.

Studies on spinal and peripheral muscles from patients with scoliosis.

This report describes part of a wider study on muscles from patients with adolescent idiopathic scoliosis. The aim of the study was to clarify if there exists a side-related pathology in the spinal musculature and if extraspinal muscles are abnormal in scoliosis patients. In scoliotic patients, both spinal and peripheral muscles showed frequent abnormalities when examined morphologically and histometrically by light and electron microscopy. Idiopathic scoliosis patients differed from the others. Morphologic pathology seemed worse on the concave side. A mild Type I fiber atrophy occurred in spinal muscles on the concave side and in the deitoids. A generalized tendency towards small myofibers was also noted. The findings suggest that there is a generalized specific neuromuscular disorder causing idiopathic scoliosis.

Premature aging changes in neuromuscular junctions of transgenic mice with an extra human CuZnSOD gene: A model for tongue pathology in Down's syndrome

We examined the tongue muscles in several strains of transgenic mice carrying the human Zn-Cu superoxide dismutase (CuZnSOD) gene. The presence of the extra gene was confirmed in mated progeny and the gene product activity was measured in the tongue and found to be much higher than in normal littermate controls. Using electron microscopic morphometry, the neuromuscular junctions of the transgenic mice showed significant changes resembling excessive aging, with atrophy, degeneration, withdrawal, and sometimes destruction of the terminal axons, as well as the development of multiple small terminals. The myofibers showed little change except for slight hypertrophy and an increased variability in size. They also had more megamitochondria, fat droplets and lipofuscin bodies. Excess CuZnSOD generates H2O2 and hydroxyl radicals which affect both NMJ membranes and plasticity, and which may produce premature aging. The findings resemble those observed in tongues of patients with Downs syndrome, in whom an extra CuZnSOD gene is present as part of the trisomy of chromosome 21.

T-2 toxin effect on bacterial infection and leukocyte functions.

The effects of T-2 toxin on bacterial infection and leukocyte function and structure were examined in vivo and in vitro. Rats were innoculated with staphylococci after pretreatment with or without T-2 toxin. The T-2 pretreated rats failed to mount a cellular response to the bacteria. Blood and bone marrow cells were markedly suppressed by the T-2 toxin, the myeloid series being the most affected. In vitro studies with human leukocytes showed that small, nonkilling doses of T-2 toxin inhibited chemotaxis, chemiluminescence stimulated by bacteria, and phagocytosis of bacteria. It was concluded that this inhibition may contribute towards sepsis and rapid onset of death in T-2 toxin poisoning.

The effect of T-2 toxin on human platelets

Human platelets were incubated with T-2 toxin, the most toxic component of Fusarium fungi, at doses of 5 to 500 micrograms/10(9) platelets. A dose-related inhibition of platelet aggregation and release of dense bodies (these consist mainly of serotonin-containing granules) were observed. A change in membrane permeability in the absence of shape changes was also demonstrated by a heavy metal impregnation technique. There was no correlated inhibition of thromboxane synthesis or significant alterations in platelet calcium content. The microtubular system was also unaffected. Suppressed platelet aggregation may contribute to the lethal hemorrhagic phenomenon associated with intoxication by fusarial toxins in man and animals.

Effect of glutaraldehyde and urea embedding on intracellular ionic elements: X-ray microanalysis of skeletal muscle and myocardium

Embedding without dehydration in a polymerizable mixture of glutataldehyde and urea was tested on skeletal muscle and myocardium prepared in various ways. This method, which theoretically should decrease electrolyte disturbances, appears preferable to conventional techniques for electron microscope X-ray microanalysis and histochemical studies. Analysis of minimally treated tissues showed that chlorine and calcium are easily detectable as intracellular elements when precipitated with silver and antimony, respectively. Glutaraldehyde + urea embedding proved visually and analytically superior to Epon in preserving ionic stability. An experimentally produced increase in intracellular myocardial calcium was also better reflected by this method. Several points of interest relating to nuclear calcium shifts in the myocardium were noted.

X-ray fluorescence analysis of muscles in scoliosis.

X-ray fluorescence spectrometry was used to determine calcium, copper, and zinc concentrations in paraspinal and gluteal muscles obtained during spinal surgery from patients with scoliosis. Samples of 1-3 mg were sufficient to demonstrate that calcium was higher in idiopathic than in other forms of scoliosis or in normal control muscles. It is suggested that a calcium-related neuromuscular defect could be an important factor in the genesis of idiopathic scoliosis

Chronic Self-Perpetuating Arthritis Induced in Rabbits by a Cell-Free Extract of Group A Streptococci

Summary Self-perpetuating arthritis was induced in knee joints of rabbits by intraarticular injections of large amounts of cell free extract derived from group A streptococci disintegrated mechanically. The pathological alterations were characterized by synovial lining cell proliferation, polymorphonuclear and mononuclear cell infiltration with the appearance of pseudo-follicles and pannus formation. Electron microscopical proliferation of B cells was predominant. An active inflammatory exudate and numerous new capillaries were also seen. The induced arthritis was self-perpetuating and appears to resemble human rheumatoid arthritis. This research project has been supported by the Joint Research Fund of the Hebrew University— Hadassah Medical School and Dental Medicine and the Hadassah Medical Organisation.

Elevated concentrations of elements and abnormalities of neuromuscular junctions in tongue muscles of Down's syndrome

X-ray spectrometry was used to measure the concentrations of calcium, iron, copper and zinc in tongue muscles from patients with Downs syndrome (DS) undergoing partial glossectomy. Similar measurements on samples from autopsies served as controls. Electron microscopy was used to examine neuromuscular junctions. The calcium and copper were significantly elevated and correlated in DS while the iron and zinc showed little change. The copper increase is probably connected with the known high level of Zn-Cu superoxide dismutase (SOD), coded for by chromosome 21. (In DS there is a trisomy 21). The excess of SOD may interfere with free radicals needed for excitation-contraction coupling and may be instrumental in damaging junctional membranes. The high calcium may result from such membrane damage. It is suggested that neuromuscular junction pathology, either genetic or free radical induced, may cause the tongue weakness in DS.

Effect of specimen preparation on intracellular myocardial calcium

SummaryCalcium concentration and intracellular localization were investigated using the electron microscopic X-ray analyser (EMMA-4) in preparations of dog myocardial tissues fixed either in glutaraldehyde, osmium tetroxide or potassium pyroantimonate plus osmium tetroxide.Calcium could be detected with all the fixatives, but at varying efficiency. Glutaraldehyde fixation showed small detectable amounts of calcium and without special localization except in the nucleus. Osmium fixation showed much higher, but still poorly localized concentrations. The pyroantimonate technique produced the highest calcium concentrations and loci of statistically significant concentrations. Preparations stained with uranyl acetate or lead citrate showed well-visualized precipitates but no detectable calcium concentrations.