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Biomedical subjects

J Cieślak

Publications and source records attributed to J Cieślak.

At least 19 recordsLinked to original sources
PubMed2003

Conceptual "Heat-Driven" approach to the synthesis of DNA oligonucleotides on microarrays.

The discovery of deoxyribonucleoside cyclic N-acylphosphoramidites, a novel class of phosphoramidite monomers for solid-phase oligonucleotide synthesis, has led to the development of a number of phosphate protecting groups that can be cleaved from DNA oligonucleotides under thermolytic neutral conditions. These include the 2-(N-formyl-N-methyl)aminoethyl, 4-oxopentyl, 3-(N-tert-butyl)carboxamido-1-propyl, 3-(2-pyridyl)-1-propyl, 2-[N-methyl-N-(2-pyridyl)]aminoethyl, and 4-methythiobutyl groups. When used for 5'-hydroxyl protection of nucleosides, the analogous 1-phenyl-2-[N-methyl-N-(2-pyridyl)]aminoethyloxycarbonyl group exhibited excellent thermolytic properties, which may permit an iterative "heat-driven" synthesis of DNA oligonucleotides on microarrays. In this regard, progress has been made toward the use of deoxyribonucleoside cyclic N-acylphosphoramidites in solid-phase oligonucleotide syntheses without nucleobase protection. Given that deoxyribonucleoside cyclic N-acylphosphoramidites produce oligonucleotides with heat-sensitive phosphate protecting groups, blocking the 5'-hydroxyl of these monomers with, for example, the thermolabile 1-phenyl-2-[N-methyl-N-(2-pyridyl)]aminoethyloxycarbonyl group may provide a convenient thermo-controlled method for the synthesis of oligonucleotides on microarrays.

Deoxyribonucleosides↗
PubMed2001

Nucleoside phosphate analogues of biological interest, and their synthesis via aryl nucleoside H-phosphonates as intermediates.

This review presents a brief account of the chemistry and mechanistic aspects of aryl H-phosphonates, and selected applications of this class of compounds as intermediates in the synthesis of a wide range of biologically important analogues of nucleoside phosphates, and oligonucleotides, in which the phosphate moieties are replaced by other structurally related groups. The aryl nucleoside H-phosphonates, compounds of controlled reactivity, have proven to be more versatile and superior to various mixed anhydrides as synthetic intermediates, particularly for preparation of nucleotide analogues bearing P-N or P-S bonds in various configurational arrangements at the phosphate moiety.

Catalysis↗
PubMed2000

Aryl H-phosphonates. 12. Synthetic and (31)P NMR studies on the preparation of nucleoside H-phosphonothioate and nucleoside H-phosphonodithioate monoesters.

Transformation of nucleoside H-phosphonate monoesters into the corresponding H-phosphonothioate and H-phosphonodithioate derivatives and possible side-reactions that may accompany this process were studied using (31)P NMR spectroscopy. These provided new insight into a possible mechanism involved in this transformation and constituted the basis for development of efficient methods for the preparation of nucleoside H-phosphonothioate and nucleoside H-phosphonodithioate monoesters using readily available H-phosphonate monoesters as starting materials.

Esters↗
PubMed1990

[Results of treatment of cross-bite at the time of milk teeth and in the first period of teeth exchange].

The results of cross-bite treatment in the period of milk teeth and at the beginning of teeth exchange were analysed. In 49 cases (81%) out of 60 treated at the time of milk teeth good therapeutic results were obtained (cure in 51% and improvement in 30%). In 60 cases (80%) out of 75 treated in the beginning of the exchange the results were good (cure in 42% and improvement in 38%). Devices used by the patients and the length of time during the day and the length of the treatment are described.

Child↗
PubMed1981

The X-ray structural investigation of 6-(n,n-1,6-hexyleneformamidine)-penicillanic acid (mecillinam).

A new type of 6-formamidinepenicillanic acid in which the omega-nitrogen atom is involved in the azaheptane ring (mecillinam) having a strong selective activity against Gram-negative bacteria strains has been investigated by the X-ray single-crystal diffraction methods using crystals in the solvated state. The conformation of penam part as well as of the amidine group is discussed. Two independent molecules of mecillinam found in the asymmetric unit of the crystal cell differ from each other in their detailed conformations. The problem of the stability of the compound has been discussed also.

Amdinocillin↗
PubMed1978

Dextran T 500--induction of spreading in Ehrlich ascites tumour cells on glass surface.

The experiments were carried out in order to find factors which could induce attachment and spreading of Ehrlich ascites tumour (EAT) cells on solid substrata. In normal culture media, serum-free as well as serum-containing, these cells did not spread and very weakly attached onto glass. It was found that after coating the cell surfaces with dextran T 500 the EAT cells strongly attached and spread extensively on glass. This spreading could be inhibited or reversed by washing out the dextran or adding calf serum. Dextran T 500 caused rapid spreading also in chick embryo fibroblasts and mouse lymphocytes. Some aspects of these results in connection with contemporary views concerning the processes of cell attachment and spreading are discussed.

Animals↗