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Biomedical subjects

D Kessler

Publications and source records attributed to D Kessler.

At least 73 records · Page 4Linked to original sources
PubMed1985

[Osteoporosis in corticoid therapy of patients with chronic obstructive respiratory tract diseases].

Two groups of patients with chronic obstructive lung diseases were investigated on presence of osteoporosis. If the diagnosis was made by clinical statement and X-ray signs of manifested osteoporosis, we found osteoporosis in 5.2 p.c. of all patients with corticosteroid treatment. If we used special X-ray methods after Barnett and Nordin resp. Singh, we found osteoporosis in 15.6 p.c. of all patients with corticosteroid treatment. In the present publication our own experiences with these special X-ray methods are described. They have their indication above all in women over 50 years resp. men over 60 years and in patients with concomitant diseases causing osteoporosis.

Adrenal Cortex Hormones↗
PubMed1984

Calcium binding sites in plasmodia of Physarum polycephalum as revealed by the pyroantimonate technique.

Plasmodia of the acellular slime mold, Physarum polycephalum, were treated with an osmium tetroxide fixative containing potassium pyroantimonate to precipitate calcium and thereby localize calcium binding sites and sites of increased calcium concentration. Dense calcium pyroantimonate precipitates were detected within the nucleoli. The distribution of these precipitates during interphase and mitosis coincides with the distribution of the unique minichromosomes in Physarum, i.e., the numerous short pieces of extrachromosomal nucleolar chromatin containing segments of amplified DNA coding for ribosomal RNA. Calcium pyroantimonate precipitates were present as frequent dense granules in the mitochondrial matrix and as fine precipitates in the mitochondrial nucleoid. Large calcium-containing precipitates were seen within cytoplasmic vacuoles, confirming reports by others. In addition, we have identified calcium binding sites along the cytoplasmic surface of the plasma membrane. The distribution of calcium within the plasmodium is discussed in relation to the assembly of the mitotic spindle and the regulation of cell motility.

Antimony↗
PubMed1983

Macrophage mediated damage to rat lenses in culture: a possible model for uveitis-associated cataract.

Rat lenses incubated in the presence of "activated" murine peritoneal macrophages are markedly impaired in their ability to accumulate certain radio-labeled compounds from the culture medium whereas incubation with resident macrophages has no such effect. The damage to the lens can be prevented in part by addition of certain antioxidants to the culture medium. The results suggest that mediators released by activated macrophages may be involved in initiation of the cataracts associated with chronic ocular inflammation.

Animals↗
PubMed1981

Ultrafast laser scanner microscope: design and construction.

The design of an ultrafast laser scanner microscope has been completed, and an experimental model has been constructed. Details of the novel objective lens design, the automatic focus system, the high-speed polygon scanner and the fast clock system are given. Results from initial tolerance testing as well as the first recorded images are presented.

Microscopy↗
PubMed1980

Physarum myosin light chain binds calcium.

Myosin from the slime mold Physarum polycephalum contains three sizes of polypeptides: a heavy chain and two light chains, LC-1 and LC-2. Using a simple qualitative test for calcium binding by comparing electrophoretic migration of the polypeptides in sodium dodecyl sulfate (SDS) acrylamide gels in the presence and absence of calcium, we have found that Physarum myosin light chain LC-2 migrates with an apparent molecular weight of 16,900 daltons in the presence of the metal ion chelator ethylene glycol bis (B-aminoethyl ether) N,N'-tetraacetic acid (EGTA). However, if calcium chloride is added to the sample prior to electrophoresis, the apparent molecular weight decreases to 16,100. Lanthanide and cadmium ions, but not magnesium, can substitute for calcium. Because the ionic radii of Ca2+, La3+, and Cd2+ are almost identical, we conclude that Physarum myosin LC-2 possesses a very size-specific binding site for calcium. Physarum myosin LC-1 and the heavy chain give no evidence for binding calcium by this test. Since cytoplasmic streaming in the plasmodium of Physarum requires calcium, our evidence indicates that the calcium-binding property of Physarum myosin LC-2 may be important in regulating the production of force by actomyosin in the ectoplasm. Unexpectedly, the myosin light chain in Physarum capable of binding calcium, LC-2, is the essential light chain, while LC-1 is a member of the regulatory class of myosin light chains [V. T. Nachmias, personal communication]. Until now, essential myosin light chains have not been shown to have high affinity divalent cation binding sites. This means a new version of the myosin-based model for actomyosin regulation by calcium may be required to explain cytoplasmic movement in Physarum, and perhaps in other motile systems involving cytoplasmic myosins as well.

Actomyosin↗
PubMed1976

Actomyosin content of Physarum plasmodia and detection of immunological cross-reactions with myosins from related species.

The content of myosin in plasmodia of the myxomycete Physarum polycephalum was measured by an immunological technique, quantitative microcomplement (C') fixation. Migrating plasmodia (starved after growth on rolled oats) contained 0.60 +/- 0.08 (SD) mg myosin per g fresh plasmodia. Myosin comprised 0.77% +/- 0.05 (SD) of the total plasmodial protein. When total plasmodial proteins were separated by electrophoresis on SDS-polyacrylamide gels, a large amount of protein appeared in a band comigrating with muscle actin. Densitometry performed after Coomassie blue staining indicated that as much as 15-25% of the total protein in the plasmodium could be actin. This gives an actin/myosin ratio by weight in the myxomycete plasmodium as high as 19-33, a very "actin-rich" actomyosin compared with rabbit skeletal muscle actomyosin with an actin/myosin ratio of 0.6. Starvation stimulates rapid migration and is correlated with a higher percent of both myosin and actin in the total protein of the plasmodium compared with normally growing cultures. Immunological cross-reaction of myosins from a variety of species was measured by C' fixation using an antiserum produced against purified native myosin from P. polycephalum. Although myxomycete and vertebrate striated muscle myosins have very similar morphological and biochemical properties, and apparently possess similar binding properties to F-actin, only myosins from myxomycetes in the order Physarales, rather closely related to P. polycephalum, gave detectable cross-reactions. This finding suggests that many amino acid sequences in myosin have been variable during evolution.

Actins↗
PubMed1976

Antibody to Physarum myosin. I. Preparation and functional effects.

Preparation of antibody to Physarum myosin is described, and evidence is presented that the antibody is specific for this molecule. A diffusion coefficient of 1 X 10(-7) cm2/s is estimated. The antibody interfered with myosin enzyme activity and with superprecipitation of actomyosin. It did not cross-react with rabbit striated muscle myosin.

Actomyosin↗