Search PubMed⌕ Search

Biomedical subjects

J Leger

Publications and source records attributed to J Leger.

At least 91 records · Page 5Linked to original sources
PubMed1984

Fiber types and myosin types in human atrial and ventricular myocardium. An anatomical description.

Hybridomas were prepared from mice immunized with myosin from the enlarged left ventricle of a 53-year-old female with an obstructive cardiomyopathy. The specificity of 15 monoclonal antibodies to myosin heavy chains was assessed by the reactivity of muscle extracts and of chymotryptic myosin fragments of different sizes with these antibodies, as determined by the immune replicate technique; some of the monoclonal antibodies cross-reacted only with the ventricular V3-type myosin from hypothyroid rats, whereas the other antibodies cross-reacted both with the latter and with the ventricular V1-type myosins from normal young rats. Immunological heterogeneity of the fibers from human atrial muscles and from human ventricular muscles was detected by some of the antimyosin antibodies by means of indirect immunofluorescence. Histochemical fiber heterogeneity was also detected by adenosine triphosphatase staining of the same tissues. Because of the close correspondence observed between the immunological and histochemical responses of atrial fibers, it has been postulated that at least two distinct types of myosin exist in the human atrium, each myosin form being histochemically related to either alpha- or beta-like ventricular myosin heavy chains. In contrast, there was no direct correspondence between the two experimental approaches in human ventricles, and it is postulated that at least three distinct types of myosin exist within the human ventricles, one V1-type myosin, presumably corresponding to the very rare fibers with an alkaline-stable adenosine triphosphatase activity, and two other V3-type myosins corresponding to immunologically different fibers, each having an alkaline-labile adenosine triphosphatase activity. Monoclonal antibodies that can distinguish among the different myosin variants were further used to provide the basis for an anatomical description of fiber types and myosin types within the human atrial and ventricular myocardium in the whole hearts of two young boys who died sudden violent deaths. Small zones of myosin variation were seen to be scattered, but probably not randomly distributed, within large areas of myocardium in which the cellular distribution of myosin was constant; the large areas had one myosin distribution specific for each cardiac cavity. No clear-cut conclusions can yet be made concerning the physiological role of the regional variations observed in the distribution of the different molecular forms of myosin.

Adenosine Triphosphatases↗
PubMed1984

[Refractory anemia with an excess of blasts: evidence for 2 evolving groups in a group of 56 patients].

Cytological and kinetic findings in 56 patients with refractory anemia with excess blasts (RAEB) were studied. The different statistical methods used produce similar results: our group of patients can be separated by cytological parameters in two populations (overt leukemic or hematologically stable evolution). Different functional lesions may be responsible for these two types; pluripotential stem cell dysfunction in the first case and abnormality of the granulocytic committed stem cell in the second. A score, based on a small number of simple and reliable parameters, is able to distinguish these two populations.

Adolescent↗
PubMed1983

Myosin light chains in normal and pathological human skeletal muscles.

Thirty-nine human skeletal muscle biopsies from 24 individuals were classified as normal, neuropathic, or myopathic muscle according to classical clinical observations and histopathological properties of the muscles. The content in myosin light chains (LC) of each muscle sample was analyzed by means of a new technique of polyacrylamide gel electrophoresis that gives an improved discrimination, involving isoelectrofocusing of the muscle homogenate for the first dimension and successive migration in a urea-containing gel for the second dimension. Four different LC patterns have been observed in the normal muscles; these four patterns and three different ones have been observed in the pathological muscles. No apparent correlation exists between the myosin LC content and the histochemical fiber typing. It is concluded that the myosin LC are apparently not a useful marker to detect the normality or the pathology of human muscle.

Amyotrophic Lateral Sclerosis↗
PubMed1980

High rate of long-term survivals in AML treated by chemotherapy and androgenotherapy: a pilot study.

An unexpectedly high rate of long-term survivors in acute myeloid leukemia (AML) has been observed in a group of patients who achieved a first complete remission (CR) after induction of a therapeutic regimen including daunorubidomycine, vincristine, prednisone and stanozolol, and anabolizing steroid. The rate of CR was 52%. Maintenance therapy was very simple and the only association with stanozolol during this period suggested to us that an androgen, at low dosages, might be responsible for the unusual long-term survival time (45 months with a 95% confidence limit from 30 to 86 months). On the basis of our first observation, high dosages of the androgen were used during the induction phase of treatment but failed to demonstrate any advantage when associated with a drug regimen, including cytosine arabinoside (ARA-C). The reevaluation of each parameter for our group of patients did not allow selection of patients in terms of their age or the hematologic data obtained at presentation. Effects of androgen on the socalled normal hemopoietic cells and on the leukemic cells are discussed, particularly the possible antagonistic effect with ARA-C. A prospective statement is made concerning the possible condition of the prolongation of the complete remission in AML according to some experimental data which enforce the stimulative activity of androgen on the myeloid proliferation.

Adolescent↗
PubMed1980

The incorporation of radioactive lysine or tyrosine into cardiac and skeletal myofibrillar and non-myofibrillar contractile proteins.

The labelled amino acids incorporation into cardiac and skeletal contractile proteins has been compared after a single injection of 3H lysine, repeated injections of 3H lysine during 1 or 6 hours or after a continuous infusion of both 3H-lysine and 14C-tyrosine. The myofibrillar incorporation was higher in the heart than in the skeletal muscle. Myosin heavy chains and actin have been prepared using gel filtration. The incorporation was again higher in the heart for both these proteins but the labelling of actin in both the muscles reaches rapidly a plateau in contrast with myosin, suggesting that these two proteins possess a different precursor pool. Myosin heavy chains prepared from the supernatant obtained after a relaxing treatment were more labelled than those extracted from myofibrils. These heavy chains from the supernatant were presumably newly synthetized and not yet incorporated into myofibrils. They also were more labelled in the heart than in the skeletal muscle which means that the myosin synthesis itself was different and not the process of assembly of the myofibrils.

Actins↗
PubMed1979

Species-dependent immunological differences between various mammalian cardiac tropomyosins.

Antisera were produced from guinea-pigs against purified pig or rat cardiac tropomyosins and antigen-antibody interactions were analyzed by the micro-complement fixation technique. Immunoadsorption with purified tropomyosins coupled with CN Br-activated Sepharose 4B enabled us to establish that these antisera were only specific to tropomyosin and not to other contractile proteins. Direct cross-reactions and competition experiments performed with both the above antisera indicated quantitative differences in the maximum amount of complement fixed by tropomyosins from various heterologous species (man, beef, pig, rabbit, rat and mouse). These data provide direct evidence that mammalian cardiac tropomyosin is species-specific.

Animals↗
PubMed1979

Detection of antibodies specific to sodium dodecyl sulfate-treated proteins.

Heavy meromyosin (HMM) denatured by sodium dodecyl sulfate (SDS) was injected into guinea pigs, either in the presence of 1 mg SDS/mg protein or after chromatography on Sephadex G-10 to remove detergent excess. Antigen-antibody interactions were analyzed by the microcomplement fixation technique. When HMM was injected in the presence of excess of SDS, the microcomplement fixation curves exhibited two maxima; one was specific to the random coil configuration of heavy meromyosin or myosin, and the other was common to several SDS-protein complexes. The latter peak disappeared when the excess SDS was removed from the immunogen by chromatography. Results showed the presence of antibodies directed either against SDS or against the non-specific SDS protein link.

Antibody Specificity↗
PubMed1979

Effect of cardiac and skeletal tropomyosin on Mg2+-actomyosin ATPase.

Tropomyosin, one of the proteins regulating the sarcomere, was prepared from pig heart and rabbit skeletal muscles. The effect of these two different tropomyosins was studied between 0.5 and 10 mM of Mg2+ at a constant ATP concentration (1 mM) on reconstituted actomyosin prepared from pig heart myosin and rabbit skeletal actin. Cardiac and skeletal tropomyosin both activated the ATPase at low Mg2+ concentrations and inhibited it above 3 mM. The pig heart and rabbit skeletal tropomyosins which contain two isomers, alpha alpha and alpha beta, respectively has very similar effects on actomyosin ATPase.

Actomyosin↗
PubMed1977

Immunochemical evidence for the species-specificity of mammalian cardiac myosin and heavy meromyosin.

Structural differences between various myosins were investigated by means of antibodies to heavy meromyosin, a tryptic subfragment of myosin. Heavy meromyosin was purified from rabbit white skeletal and from pig and human cardiac muscles by gel filtration, and antisera were produced in guinea pigs. Analyses, carried out with the quantitative micro-complement fixation technique, indicated that the antibodies were specific to heavy meromyosin and myosin and not to other contractile proteins. For each muscle type, the corresponding intact myosin reacted, and the degree of dixation was always lower than with heavy meromyosin (50 and 70% fixation respectively). This vertical shift was the same for the three muscle types, indicating that the heavy meromyosin represent corresponding fragments of the myosin molecule from one muscle to the other. Antisera to pig or human cardiac heavy meromyosin clearly distinguished antigens (heavy meromyosins, myosins, or crude extracts) from the ventricles of various heterologous species. Relative to pig, the immunological distances were 50 for the rabbit, 73 for the rat and greater than 100 for human and mice. Relative to human, these values were 20 for the rat, 60 for the rabbit, 72 for the pig. These data provide direct evidence that mammalian cardiac myosin is species-specific.

Adenosine Triphosphatases↗
PubMed1976

A comparative study of skeletal and cardiac tropomyosins: subunits, thiol group content and biological activities.

The subunit composition, the thiol group content and the biological activities of cardiac tropomyosins (TM) of various animal species were compared. Cardiac TM from small animals such as rabbit, guinea-pig, rat and dog contain 2 SH/mole and were resolved into one band on SDS and acid urea electrophoresis and into two bands on alkaline urea electrophoresis. Chicken cardiac TM likewise gave one band and it contains 4 SH/mole. In contrast pig, sheep and human cardiac TM contain respectively 2.6, 2.4, and 2.4 SH/mole and were resolved into two bands alpha and beta on the different electrophoresis systems used, with a beta:alpha ratio respectively of I:4.2, I:4.6, I:4.8. The alpha-TM components from sheep skeletal and pig and sheep cardiac muscles were more positively charged than the rabbit skeletal alpha-TM component, as shown in alkaline urea electrophoresis system. The alphaalpha and alphabeta combinations of dimers found for skeletal muscle by other authors, were also found for cardiac pig TM. All the TM have the same effect on the Ca2+-stimulated ATPase activity of desensitized actomyosin (DAM) and on the Mg2+-stimulated ATPase activity of DAM with troponin-complex. This work suggests that the subunits of the TM from skeletal and cardiac muscles are heterogenous in their M.W. and their charges and that in the heart as well as in skeletal muscle a relationship seems to exist between the amount of the beta component and the speed of contraction of the muscle: a higher amount of this component was found in the bulky hearts which are also those which contract slower.

Actomyosin↗