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Biomedical subjects

J Eichler

Publications and source records attributed to J Eichler.

140 records · Page 8Linked to original sources
PubMedDate not supplied

Inclusion volume solid-phase synthesis.

Solid-phase synthesis of peptides was carried out using only the volume of the solvent included in the swollen solid-phase resin heads (inclusion volume synthesis). This approach enables (i) the use of higher concentrations of activated amino acids, resulting in increased coupling rates, (ii) drastically decreased consumption of solvents, and (iii) the construction of multiple peptide synthesizers having virtually no reaction vessels.

Amino Acids↗
PubMedDate not supplied

Novel glycoproteins of the halophilic archaeon Haloferax volcanii.

Archaea possess many eukaryote-like properties, including the ability to glycosylate proteins. Using oligosaccharide staining and lectin binding, this study revealed the existence of several glycosylated Haloferax volcanii membrane proteins, besides the previously reported surface layer (S-layer) glycoprotein. While the presence of glycoproteins in archaeal S-layers and flagella is well-documented, few archaeal glycoproteins that are not part of these structures have been reported. The glycosylated 150, 98, 58 and 54 kDa protein species detected were neither precursors nor breakdown products of the 190 kDa S-layer glycoprotein. Furthermore, these novel glycoproteins were outwardly oriented and intimately associated with the membrane.

Aminosalicylic Acid↗
PubMedDate not supplied

Parameters for argon laser surgery of the lower human turbinates. In vitro experiments.

On 8 human lower turbinates in vitro, experiments were performed using an argon laser with a power of 1-10 W, a beam diameter of 0.2 and 2 mm. For clinical laser surgery of the turbinates 1-2 W is sufficient. Drilling, incision, coagulation and vaporizing experiments, were done on the tissue of the lower turbinates. The results of this laser surgery are discussed and compared with present-day surgical methods such as conchotomy, cutting of the posterior ends by slinging, and electrocautery of the lower turbinates.

Aged↗
PubMedDate not supplied

[Experimental hemiglossectomy with an argon laser on tongues from dead humans and of liver rabbits].

On 8 tongues of decreased humans and 2 live rabbit tongues, drilling and incision experiments were performed using an argon laser. With a power of 50 W a hemiglossectomy was performed in 3-4 min. The average thickness of the tongue was 2 cm and the incision length 10 cm. It was shown on the liver rabbit tongue that no bleeding occurs during a partial hemiglossectomy except at the arteria lingualis. The macroscopical and histological changes of the tissue are described, viz, the carbonization zones, the irreparable cell damage and the coagulation and the hyperaemic edge. The cutting speeds and the incision and drilling data for tongues of varying thickness provide information on the technical conditions for clinical application. In addition, temperatures in the tissue during incision were recorded. The advantages of laser surgery of the tongue are compared with those achieved with the electric knife and scalpel.

Aged↗
PubMedDate not supplied

Evaluation of cotton as a carrier for solid-phase peptide synthesis.

Cotton as a new support for the solid-phase synthesis of peptides was evaluated under the conditions of both Boc/Bzl and Fmoc/But strategy. Syntheses of peptides containing only bifunctional amino acids gave comparable results, but peptides containing trifunctional amino acids are clearly advantageously synthesized using the Fmoc approach. The comparison of cotton with other planar carriers (paper or polypropylene membranes) and with classical pellicular ones has shown practical applicability of cotton as the replacement of more sophisticated carriers. N-Methylimidazole was shown to be the optimal acylation catalyst for the modification of the cellulose carrier. Stability of the ester bond to the cotton was studied and shown to be adequate for the syntheses of small to medium size peptides. A relatively low level of substitution of cotton carrier in connection with its ability to soak the solvent was used for the complete elimination of a synthetic vessel. Couplings can be performed by wetting the carrier with the coupling solution, and all solvents can be removed either by squeezing it together with a porous material (paper) or by centrifugation. This leads to a significant decrease of solvent consumption. The efficiency of solvent elimination by centrifugation was demonstrated by the synthesis of model peptide ACP 65-74 in which only one wash between coupling and deprotection and between deprotection and coupling was used and which afforded the product of the same quality as the product synthesized using the standard protocol. Bromophenol blue monitoring has been proven as the optimal way of monitoring the acylation reaction progress. Peptides directly bound to cotton were shown to be useful in enzyme-linked immunosorbent assay tests.

Acylation↗
PubMedDate not supplied

Simulation of continuous solid phase synthesis: synthesis of methionine enkephalin and its analogs.

The method of continuous solid phase synthesis, i.e., synthesis performed on a continual carrier, transferable from one synthetic compartment to another by means of a mechanical device, allows one to perform multiple synthetic steps simultaneously on different regions of the carrier. This procedure was tested on the synthesis of methionine enkephalin and its analogs. Products, obtained in reasonable yields, were fully characterized. Possible arrangements and the use of continuous solid phase synthesizers are discussed.

Amino Acid Sequence↗
PubMedDate not supplied

Cyclic peptide template combinatorial libraries: synthesis and identification of chymotrypsin inhibitors.

A cyclic peptide template combinatorial library in a positional scanning format, composed of three positional libraries, was synthesized using solid-phase chemistry and four orthogonal protecting groups (Fmoc, Boc, Dde, OAll). The cyclic peptide template is composed of three lysine residues and one glutamic acid residue. The chemical diversity was introduced by acylating the epsilon-amino groups of the lysine residues using 10 carboxylic acids in addition to the 20 proteinogenic amino acids. The library components have been shown to be stable towards proteolytic degradation. Compounds with chymotrypsin inhibitory activity were identified through the screening of this library.

Acylation↗