A New Approach to the Production of Bioresorbable Suture Materials with Biological Activity

2018 ◽  
Vol 935 ◽  
pp. 94-99
Author(s):  
Mukhamed A. Khavpachev ◽  
E.S. Trofimchuk ◽  
N.I. Nikonorova
Keyword(s):  
Biological Activity ◽  
Biologically Active ◽  
Degree Of Crystallinity ◽  
Uniaxial Deformation ◽  
Suture Materials ◽  
Ethanol Mixture ◽  
New Approach ◽  
Low Temperature Crystallization ◽  
Solvent Crazing ◽  
Temperature Crystallization

The advantages of structural-mechanical modification of fibers by the mechanism of crazing for obtaining bioresorbable suture materials with biological activity are shown. Optimal conditions for realization of solvent crazing of polylactide fibers are determined as the stretching rate is not more than 75% / min and the ethanol content in the water-ethanol mixture is not less than 30-40% by weight. In this case, the value of yield stress decreases by 3-5 times, and the breaking elongation increases to 400-600%. The process of uniaxial deformation of fibers under these conditions is accompanied by the formation of a highly dispersed oriented structure with a pore diameter and fibrils of about 20-30 nm and bulk porosity up to 60% by volume. Moreover, the crazing of fibers based on polylactide under these conditions is accompanied by low-temperature crystallization, reaching a degree of crystallinity of 40%. The monofilaments based on polylactide containing biologically active additives (brilliant green, fuchsine) by the crazing mechanism are obtained. Such materials are promising for use in medicine as bioresorbable sutures with antibacterial activity.

Photo-assisted low temperature crystallization of solution-derived LiCoO2 thin film

2021 ◽  
Vol 138 ◽  
pp. 111241
Author(s):  
Boseon Yun ◽  
Tan Tan Bui ◽  
Paul Lee ◽  
Hayeong Jeong ◽  
Seung Beom Shin ◽  
...  
Keyword(s):  
Thin Film ◽  
Low Temperature ◽  
Low Temperature Crystallization ◽  
Temperature Crystallization

Nickel(II)- and Silver(I)-Catalyzed C–H Bond Halogenation of Anilides and Carbamates

Synthesis ◽  
2020 ◽  
Author(s):  
Ebrahim Kianmehr ◽  
Hadi Afaridoun
Keyword(s):  
Biologically Active Compounds ◽  
Biologically Active ◽  
Silver Catalyst ◽  
Active Compounds ◽  
Available N ◽  
New Approach

Abstract ortho-C–H bond halogenation of anilides and N-aryl carbamates using easily available N-halosuccinimides (NXS) as the active halogenation reagent in the presence of nickel or silver catalyst has been developed. This method provides a new approach to 2-haloanilides and carbamates, which may serve as starting materials for the synthesis of pharmaceutically and biologically active compounds.

Isoselenocyanates: Synthesis and Their Use for Preparing Selenium-Based Heterocycles

Synthesis ◽  
2021 ◽  
Author(s):  
Stefan H. Bossmann ◽  
Raul Neri
Keyword(s):  
Biological Activity ◽  
Infectious Diseases ◽  
Cancer Cells ◽  
Multicomponent Reactions ◽  
Oxidative Cyclization ◽  
Biologically Active ◽  
Organoselenium Compounds ◽  
X Ray ◽  
Synthetic Work

AbstractIsoselenocyanates (ISCs) are a class of organoselenium compounds that have been recognized as potential chemotherapeutic and chemopreventative agents against cancer(s) and infectious diseases. ISC compounds are chemically analogous to their isosteric relatives, isothiocyanates (ITCs); however, they possess increased biological activity, such as enhanced cytotoxicity against cancer cells. ISCs not only serve as significant products, but also as precursors and essential intermediates for a variety of organoselenium compounds, such as selenium-containing heterocycles, which are biologically active. While syntheses of ISCs have become less difficult to accomplish, the syntheses of selenium-containing heterocycles are often difficult due to the use of highly toxic selenium reagents. Because of this, ISCs can serve as versatile reagents for the preparation of these heterocycles. In this review, the classical and recent syntheses of ISCs will be discussed, along with notable and recent synthetic work employing ISCs to access novel selenium-containing heterocycles.1 Introduction1.1 Selenium and Health2 Isoselenocyanates2.1 Preparation of Isoselenocyanates3 Selenium-Containing Heterocycles3.1 Notable Synthetic Work3.2 Recent Synthetic Work3.2.1 Synthesis of N-(3-Methyl-4-phenyl-3H-selenazol-2-ylidene)benzamide­ Derivatives3.2.2 Synthesis and X-ray Studies of Diverse Selenourea Derivatives3.2.3 Synthesis of Heteroarene-Fused [1,2,4]Thiadiazoles/Selenadiazoles via Iodine-Promoted [3+2] Oxidative Cyclization3.2.4 2-Amino-1,3-selenazole Derivatives via Base-Promoted Multicomponent Reactions4 Conclusion

scholarly journals Isolation, Structure Elucidation, and Biological Activity of a New Alkaloid from Zanthoxylum rhetsa

2011 ◽  
Vol 6 (11) ◽  
pp. 1934578X1100601
Author(s):  
Karsten Krohn ◽  
Stephan Cludius-Brandt ◽  
Barbara Schulz ◽  
Mambatta Sreelekha ◽  
Pottachola Mohamed Shafi
Keyword(s):  
Biological Activity ◽  
Carboxylic Acid ◽  
Medicinal Plant ◽  
Plant Extract ◽  
Structure Elucidation ◽  
Biologically Active ◽  
Reduction Product ◽  
Pharmacological Properties ◽  
Evergreen Tree

Several biologically active alkaloids (1-4, 6), including a new quinazoline-6-carboxylic acid (1), were isolated from the medicinal plant Zanthoxylum rhetsa, an evergreen tree, native to subtropical areas. Whereas the pharmacological properties of the plant extract and single constituents have been widely tested, we now show that all of the metabolites have antialgal activities, all but 6 are antibacterial, and 6 and the reduction product 5 (derived from 4) are also antifungal.

scholarly journals Transforming growth factor alpha: mutation of aspartic acid 47 and leucine 48 results in different biological activities.

1988 ◽  
Vol 8 (3) ◽  
pp. 1247-1252 ◽  
Author(s):  
E Lazar ◽  
S Watanabe ◽  
S Dalton ◽  
M B Sporn
Keyword(s):  
Amino Acids ◽  
Biological Activity ◽  
Amino Acid ◽  
Growth Factor ◽  
Aspartic Acid ◽  
Transforming Growth Factor ◽  
Biologically Active ◽  
Single Amino Acid ◽  
Transforming Growth Factor Alpha ◽  
Factor Alpha

To study the relationship between the primary structure of transforming growth factor alpha (TGF-alpha) and some of its functional properties (competition with epidermal growth factor (EGF) for binding to the EGF receptor and induction of anchorage-independent growth), we introduced single amino acid mutations into the sequence for the fully processed, 50-amino-acid human TGF-alpha. The wild-type and mutant proteins were expressed in a vector by using a yeast alpha mating pheromone promoter. Mutations of two amino acids that are conserved in the family of the EGF-like peptides and are located in the carboxy-terminal part of TGF-alpha resulted in different biological effects. When aspartic acid 47 was mutated to alanine or asparagine, biological activity was retained; in contrast, substitutions of this residue with serine or glutamic acid generated mutants with reduced binding and colony-forming capacities. When leucine 48 was mutated to alanine, a complete loss of binding and colony-forming abilities resulted; mutation of leucine 48 to isoleucine or methionine resulted in very low activities. Our data suggest that these two adjacent conserved amino acids in positions 47 and 48 play different roles in defining the structure and/or biological activity of TGF-alpha and that the carboxy terminus of TGF-alpha is involved in interactions with cellular TGF-alpha receptors. The side chain of leucine 48 appears to be crucial either indirectly in determining the biologically active conformation of TGF-alpha or directly in the molecular recognition of TGF-alpha by its receptor.

A NEW APPROACH FOR INVESTIGATING HYPOTHALAMO-PITUITARY-GONADAL AND ADRENAL FEEDBACK CONTROL MECHANISMS: ACTIVE IMMUNIZATION WITH STEROIDS

1974 ◽  
Vol 76 (3) ◽  
pp. 556-569 ◽  
Author(s):  
E. Nieschlag ◽  
K. H. Usadel ◽  
H. K. Kley ◽  
U. Schwedes ◽  
K. Schöffling ◽  
...  
Keyword(s):  
Feedback Control ◽  
Leydig Cells ◽  
Positive Response ◽  
Active Immunization ◽  
Biologically Active ◽  
Control Group ◽  
Control Mechanisms ◽  
New Approach ◽  
Biological Neutralization ◽  
Group Serum

ABSTRACT A new method for the investigation of hypothalamo-pituitary-gonadal and adrenal feedback control mechanisms based on the biological neutralization of gonadal and adrenal steroids by active immunization is proposed. The regulatory influence of a given steroid in the feedback control is proved when reduction of the free, biologically active fraction of this steroid caused by antibody binding induces a positive response of the pituitary, thus effecting gonadal or adrenal hypertrophy and hyperfunction. The advantages and limitations of the new model are demonstrated by the effects of active immunization of rabbits with cortisol (F), aldosterone (Aldo), dehydroepiandrosterone (DHA), androstenedione (Δ4-A), testosterone (T), 5α-dihydrotestosterone (5α-DHT), 5β-DHT and oestradiol (E2). In the immunized animals and in a control group serum concentrations of total corticosteroids (TC), DHA, T, Δ4-A, E1, E2, LH and FSH, the percentage of binding of steroids in serum and the specificity of the antisera are determined. The testes are evaluated by histometry and the nuclear volume of the adrenocortical and Leydig cells is measured.

Significance of C-terminal cysteine modifications to the biological activity of the Saccharomyces cerevisiae a-factor mating pheromone

1991 ◽  
Vol 11 (7) ◽  
pp. 3603-3612
Author(s):  
S Marcus ◽  
G A Caldwell ◽  
D Miller ◽  
C B Xue ◽  
F Naider ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Biological Activity ◽  
Methyl Ester ◽  
Total Synthesis ◽  
Biologically Active ◽  
Structural Genes ◽  
Wild Type ◽  
Mating Pheromone ◽  
Carboxy Terminal

We have undertaken total synthesis of the Saccharomyces cerevisiae a-factor (NH2-YIIKGVFWDPAC[S-farnesyl]-COOCH3) and several Cys-12 analogs to determine the significance of S-farnesylation and carboxy-terminal methyl esterification to the biological activity of this lipopeptide mating pheromone. Replacement of either the farnesyl group or the carboxy-terminal methyl ester by a hydrogen atom resulted in marked reduction but not total loss of bioactivity as measured by a variety of assays. Moreover, both the farnesyl and methyl ester groups could be replaced by other substituents to produce biologically active analogs. The bioactivity of a-factor decreased as the number of prenyl units on the cysteine sulfur decreased from three to one, and an a-factor analog having the S-farnesyl group replaced by an S-hexadecanyl group was more active than an S-methyl a-factor analog. Thus, with two types of modifications, a-factor activity increased as the S-alkyl group became bulkier and more hydrophobic. MATa cells having deletions of the a-factor structural genes (mfal1 mfa2 mutants) were capable of mating with either sst2 or wild-type MAT alpha cells in the presence of exogenous a-factor, indicating that it is not absolutely essential for MATa cells to actively produce a-factor in order to mate. Various a-factor analogs were found to partially restore mating to these strains as well, and their relative activities in the mating restoration assay were similar to their activities in the other assays used in this study. Mating was not restored by addition of exogenous a-factor to a cross of a wild-type MAT alpha strain and a MATaste6 mutant, indicating a role of the STE6 gene product in mating in addition to its secretion of a-factor.

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