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Biomedical subjects

I Dunia

Publications and source records attributed to I Dunia.

54 records · Page 3Linked to original sources
PubMed1980

In vitro synthesis of the major lens membrane protein.

The biosynthetic activity of a polyribosomal fraction isolated from the lens fiber plasma membrane-cytoskeleton complex by DNase I treatment has been assayed. After translation of these polyribosomes in a reticulocyte cell-free system and analysis of the products by electrophoresis in sodium dodecyl sulfate gels, the preferential synthesis of a protein with an apparent molecular weight of 26,000 was observed. By means of immunochemical characterization we showed that this protein, which seems not to be synthesized by "free" polyribosomes, is identical with the major intrinsic plasma membrane protein MP26 of lens fibers. Upon storage, the molecular weight of the newly synthesized protein decreases to about 22,000, a phenomenon that has previously been observed for MP26 in isolated plasma membranes and that may be caused by the presence of a specific proteolytic cleaving site in the protein.

Actins↗
PubMed1979

Is the cytoskeleton-plasma membrane complex involved in lens protein biosynthesis?

Calf lens fiber cells contain a population of polyribosomes that direct, at least in vitro, the synthesis of a specific plasma membrane protein MP26. This protein may serve as a marker in terminal differentiation, since it is absent in the lens epithelium but appears in lens fiber plasma membranes. The MP26 manufacturing polyribosomes are found to be associated with a structural complex in which also the cytoskeleton and plasma membranes participate. They can be released from the complex by treatment with DNAse I. This result presumably reflects the involvement of actin in the linkage of the MP26 synthesizing polyribosomes to the cytoskeleton-membrane complex.

Animals↗
PubMed1979

Junctional modulation in mouse embryonal carcinoma cells by Fab fragments of rabbit anti-embryonal carcinoma cell serum.

Mouse embryonal carcinoma PCC4 cells are connected by extensive gap and tight junctions. When the cells are incubated in a medium containing Fab fragments against embryonal carcinoma F9 cells, they round up and a process of junctional removal is initiated. In particular, gap junctions are internalized and after 30 hr of incubation with the anti-F9 Fab fragments both tight and gap junctions are no longer present at the cell surface; however, the cells are still in contact by means of small attachment sites.

Animals↗
PubMed1979

Actin in mammalian lens.

In this paper evidence is provided that one of the protein components of the water-soluble fraction of the calf lens binds specifically to deoxyribonuclease I (DNAse I). On the basis of this property, the polypeptide could be purified by applying DNAse I affinity chromatography. Concomitantly a protein of Mr55000 and a rather large amount of alpha-crystallin copurify with this polypeptide, which has a molecular weight of 42000. Highly purified 42000-Mr protein was also obtained by extraction of the water-insoluble fraction of the calf lens with 2-([tris(hydroxymethyl)methyl]amino) ethanesulfonic acid followed by gel filtration. Amino acid analyses, peptide mapping and electron microscopy show that the protein obtained from both lens fractions is identical to non-muscle actin. Furthermore the amino acid composition of the 55000-Mr protein is identical to hog stomach skeletin and very similar to calf brain desmin.

Actins↗
PubMed1979

Comparative ultrastructure of Mycobacterium leprae and Mycobacterium lepraemurium cell envelopes.

The structural properties of the cell envelopes of Mycobacterium leprae and Mycobacterium lepraemurium were investigated by freeze-fracture, freeze-etching, and negative-staining techniques. Freeze-fracture split the cell wall and exposed the internal features of the peptidoglycolipid mycosidic filamentous network. The cell membrane was also split into two asymmetric faces. The external fracture face was characterized by linear arrays of intramembranous particles, whereas the protoplasmic fracture face showed randomly distributed clusters of particulate entities. Comparative analysis of the ultrastructural features observed in M. leprae and M. lepraemurium indicated that the organization of the cell envelope in these two species differed particularly with respect to the amount and complexity of the superficial peptidoglycolipid and mycosidic integument, which is poorly developed in the mycobacterium responsible for human disease.

Animals↗
PubMed1974

Correlation between the mobility of inner plasma membrane structure and agglutination by concanavalin A in two cell lines of MOPC 173 plasmocytoma cells.

Both the distribution of the concanavalin A-binding sites and the rearrangement of the intramembranous particles revealed by the freeze-etching technique, have been studied by means of two variants of the same cell line issued from MOPC 173 murine plasmocytoma. One variant does not agglutinate even in presence of high lectin concentration. It has been shown that the number of binding sites and affinity are almost the same in the two variants. The clustered distribution of intramembranous particles is induced by the interaction of the concanavalin A and the cell surface only in the variant which is agglutinable. From these results it became apparent that the clustered distribution of the membrane particulate components is an acquired feature of the plasma membrane accompanying cell agglutination.

Agglutination↗
PubMed1974

Development of junctions during differentiation of lens fibers.

Throughout the differentiation of eye lens epithelium into fibers, an extensive system of intercellular junctions develops. The junctional assembly is initially characterized by the accumulation of 9.0-nm intramembranous particles, forming linear rows in the matching plasma membranes of adjoining fibers. At the final stage of the fiber differentiation, the junctional particles are assembled in geometrically packed arrays. The formation of linear rows and bidimensional lattices of intramembranous particles probably favors reciprocal recognition of cell surfaces and specific cell-to-cell interlocking. Moreover, the existence of a rather rigid lipid core of the plasma membrane of eye lens fiber may promote the clustered distribution of intramembranous particles and facilitate the junctional assembly.

Animals↗
PubMedDate not supplied

Plasma membrane and cytoskeletal constituents in Leishmania mexicana.

The presence and the localization of actin, spectrin and ankyrin are studied by immunofluorescence and immunoblotting in Leishmania mexicana promastigotes growing in vitro. These proteins, amphitropic in nature, coexist both in soluble and insoluble forms. Our results demonstrate that the Triton insoluble form of these proteins constitutes beside tubulin the cytoskeletal scaffold of promastigotes in close association with the plasma membrane, the axoneme and the basal body of the parasite.

Actins↗
PubMedDate not supplied

Sulpiride in the treatment of somatoform disorders: results of a European observational study to characterize the responder profile.

An open, observational study was conducted in five European countries to obtain information concerning the profile of patients responding to sulpiride. A total of 1,356 patients were evaluable for analysis. The majority of patients (81.1%) had at least three principal somatic complaints; asthenia being the most common, followed by dizziness and headache. Most patients (76.0%) were rated as moderately to extremely ill according to the Clinical Global Impression (CGI) severity score. All patients received oral sulpiride for 3-6 weeks (mean dose, 175 mg/day). Sulpiride demonstrated good efficacy as shown by a reduction in the incidence and severity of somatic complaints, and an improvement in CGI severity score and the Hopkins Symptom Checklist--58 items. Based on a CGI rating of very much or much improved, 58.2% of patients were rated as responders. Sulpiride was well tolerated. There were no serious adverse events and only 16 patients (1.2%) were withdrawn prematurely from the study due to adverse events. There were no differences between the countries regarding the patients' profile or their response to sulpiride. Thus, the prescription profile of sulpiride appears not to be culturally dependent.

Adolescent↗
PubMedDate not supplied

Freeze-etching and freeze-fracture structural features of cell envelopes in mycobacteria and leprosy derived corynebacteria.

The structural properties of the cell wall and cell membrane of several mycobacteria and of Leprosy Derived Corynebacteria are investigated by freeze-etching and freeze-fracture. In all cases the freeze-fracture split the cell wall in two asymmetric halves. The cell wall fracture faces of the mycobacteria are characterized by a filamentous network which vary with respect to the amount and complexity among microorganism of the same species and even more of different species. In LDC the structure organization of the cell wall and cell membrane differs from that of mycobacteria. The most stricking difference is the presence on the fracture faces of the LDC cell wall of different classes of particulated entities of yet unknown nature. In the mycobacteria and LDC the periseptal annuli likely provide a potential frame for cell envelope and cell membrane assembly.

Animals↗