Biomedical subjects

S Szela

Publications and source records attributed to S Szela.

At least 19 recordsLinked to original sources

PubMed2000

Reduction-oxidation control of beta-sheet assembly in genetically engineered silk.

Genetically engineered spider dragline silk protein was modified to incorporate methionines flanking the beta-sheet forming polyalanine regions. The methionines could be selectively chemically oxidized and reduced. This chemical change altered the bulkiness and charge of the sulfhydryl groups, and in turn, the beta-sheet forming tendencies of the polyalanine domains and solubility of the protein. The genes encoding these redesigned proteins were constructed, cloned and expressed in Escherichia coli. In the reduced state (beta-mercaptoethanol) the approximately 25 kDa protein behaved similarly to native spider dragline silk, crystallizing into beta-sheets based on diffraction analysis and appearing fibrous by TEM. The addition of the methionines into the consensus dragline silk sequence did not disrupt the normal macromolecular assembly behavior of the protein. In the oxidized state (phenacyl bromide) the protein did not form beta-sheet crystals and appeared morphologically featureless based on TEM. A reduction in beta-strand content was also observed upon oxidation based on FTIR and TEM analysis and confirmed by X-ray diffraction analysis. To further confirm changes in assembly behavior observed for the recombinant protein containing the methionines, a model peptide with the same repeat amino acid sequence was synthesized and characterized. Shifts in molecular weight, observed by MALDI, along with corresponding changes in crystallinity, by electron diffraction, agreed with the changes expected on activation and deactivation of the redox trigger. These results support the use of a redox trigger as a useful feature with which to control the assembly of beta-sheet forming proteins.

Amino Acid Sequence↗

PubMed1992

[Factors of the "acute phase" in proliferative diseases of the hemopoietic system].

In proliferative diseases of the homeopathic system before starting and at the end of treatment, the values of 8 acute phase factors were studied simultaneously, that is: seromucoid, sialic acid, alpha 1 acid glycoprotein, alpha 1 antitrypsin, haptoglobin, ceruloplasmin, transferrin, and fibrinogen. In chronic myeloid and lymphatic leukaemia no constant increase nor decrease of the concentration of any of the factors was found. In non-Hodgkin lymphoma the concentration of one factor -ceruloplasmin was constantly increased, and that of two factors--sialic acid and fibrinogen was decreased, while in plasmocytoma the concentration of two factors--haptoglobin and ceruloplasmin was constantly increased. At the end of treatment the concentration of certain factors was changing. In chronic myeloid leukaemia the concentration of ceruloplasmin, fibrinogen, and seromucoid was decreasing, while in non-Hodgkin lymphoma the concentration of haptoglobin and fibrinogen was increasing, in chronic lymphatic leukaemia the concentration of haptoglobin and increasing, in chronic lymphatic leukaemia the concentration of haptoglobin and transferrin was increasing, and in plasmocytoma the concentration was increasing of haptoglobin, sialic acid, and transferrin. The result of treatment in chronic myeloid leukaemia was good, in non-Hodgkin lymphoma and chronic lymphatic leukaemia--moderate, and in plasmocytoma it was least beneficial.

Acute Disease↗

PubMed1991

[Acute phase factors in anemia].

In various anaemias the values of 8 acute phase factors were determined simultaneously before and at the end of treatment: seromucoid, sialic acid, acid alpha 1-glycoprotein, alpha 1-antitrypsin, haptoglobin, ceruloplasmin, transferrin and fibrinogen. In iron-deficiency anaemia without coexistent inflammatory changes in organs the levels of 4 proteins--seromucoid, alpha 1-antitrypsin, ceruloplasmin and transferrin, were consistently raised. In iron-deficiency anemia with concomitant infection 4 proteins also were increased, but in place of alpha 1-antitrypsin the haptoglobin level was raised. In megaloblastic anaemia the ceruloplasmin level was increased, and in haemolytic anaemia one factor--sialic acid--was decreased. At the end of treatment the concentrations of certain proteins were changed depending on their specific role in various forms of anaemia and on various additional factors. In iron-deficiency anaemia without coexistent infection the concentration of seromucoid was decreased, and in this anaemia with coexistent infection alpha 1-antitrypsin, haptoglobin, and fibrinogen levels were raised, in haemolytic anaemia only fibrinogen was increased, and megaloblastic anaemia was associated with raised seromucoid level. The therapeutic result was good in all these anaemias with the exception of iron-deficiency anaemia associated with infection in which it was less propitious.

Acute-Phase Proteins↗

PubMed1990