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Biomedical subjects

M Köck

Publications and source records attributed to M Köck.

At least 37 records · Page 2Linked to original sources
PubMed1996

Secondary structural elements as a basis for antibody recognition in the immunodominant region of human immunodeficiency viruses 1 and 2.

Synthetic peptide antigens corresponding to the entire third variable region V3, the principal neutralizing determinant of the human immunodeficiency virus (HIV) envelope glycoprotein of HIV-1 subtype B (1), HIV-2 subtype A (5), and HIV-2 subtype B (7) were synthesized by solid-phase peptide synthesis (Table 1). 1 and 5 were also prepared as their GlcNAc-glycosylated forms at the natural N-glycosylation site NXT (positions 6-8; peptides 4 and 6). Additionally, the proposed beta-turn region of 1 (GPGR; positions 15-18) was altered by introducing D-Ala17 (2) and D-Pro16 (3). All compounds have been studied by two-dimensional NMR techniques. Interproton distances and 3JNH/H alpha coupling constants derived from NMR data are used as restraints in distance geometry and ENSEMBLE-Distance and angle-bound driven dynamics calculations. The stimulations led to disordered conformations except for a high propensity of a beta II-turn in the region GPXR (positions 15-18) in 1, 2, and 4. In 3 (G-D-ProGR, positions 15-18), a type beta I'-turn was mainly found instead. For peptide 7, the consensus sequence of HIV-2 subtype B, a type beta II-turn was also found although the primary structure (VSGL; positions 15-18) differs grossly from the HIV-1 peptide 1. With the exception of 2, all beta II-turns were able to form a canonically opened beta-turn by a 180 degree rotation of phi(G17). Surprisingly, compounds 5 and 6 that are highly similar to 7 showed no beta II-type turn within MSGL (positions 15-18). They form a type beta VIII-turn across the tetrapeptide SGLV (positions 16-19) together with a non-canonical turn conformation across LMSG (positions 14-17) leading to an S-conformation. The reaction of the peptides with HIV-positive sera from patients infected with different subtypes of HIV-1 and HIV-2 was tested in enzyme-linked immunosorbent assays (ELISA reactions). No HIV-2 sera reacted peptide 1 and no HIV-1 sera showed reactivity to peptide 5. We propose that certain amino acid exchanges within the V3 domain lead to altered conformations of the V3 loop resulting in antibodies that show altered binding properties to the peptide antigens used in the ELISA reactions.

Amino Acid Sequence↗
PubMed1995

cDNA structure and regulatory properties of a family of starvation-induced ribonucleases from tomato.

In previous work we have determined the primary structure of two of the five ribonucleases which are induced by phosphate starvation in cultured tomato cells. Here, we present the isolation and characterization of the cDNAs for the extracellular ribonuclease LE and the intracellular, but extravacuolar ribonuclease LX. Structural analysis of these cDNAs together with partial protein-sequencing of vacuolar ribonucleases LV1, LV2 and LV3 revealed a family of very similar ribonucleases. From these data we assume identify between ribonucleases LE and LV3 for which the targeting mechanism has to be shown. Furthermore, RNase LV1 and RNase LV2 might be posttranslational processing products of RNase LX which travel to the vacuoles after splitting off the putative ER retention signal present at RNase LX. Additionally, we show by northern blot analysis that phosphate starvation in plant cells leads to an increase in the steady-state level of this type of enzymes revealing close similarities of the plant response to a limited supply of inorganic phosphate with the PHO regulation in bacteria and fungi.

Amino Acid Sequence↗
PubMed1992

Unusual thionation of a cyclic hexapeptide. Conformational changes and dynamics.

One carbonyl oxygen of the cyclic hexapeptide cyclo(-Gly1-Pro2-Phe3-Val4-Phe5-Phe6-) (A) can be selectively exchanged with sulphur using Yokoyama's reagent. Surprisingly it was not the C=] of Gly1 but that of Phe5 which was substituted and cyclo(-Gly1-Pro2-Phe3-Val4-Phe5 psi [CS-NH]Phe6-) (B) was obtained. Thionation results in a conformational change of the peptide backbone although the C=O of Phe5 and the corresponding C=S are not involved in internal hydrogen bonds. Two isomers in slow exchange, containing a cis Gly1-Pro2 bond in a beta VIa-turn (minor) and a trans Gly-Pro bond in a beta II'-turn (major), were analyzed by restrained molecular dynamics in vacuo and in DMSO as well as using time dependent distance constraints. It is impossible to fit all experimental data to a static structure of each isomer. Interpreting the conflicting NOEs, local segment flexibility is found. MD simulations lead to a dynamic model for each structure with evidence of an equilibrium between a beta I- and beta II-turn about the Val4-Phe5 amide bond in both the cis and trans isomers. Additionally proton relaxation rates in the rotating frame (R1 rho) were measured to verify the assumption of this fast beta I/beta II equilibrium within each isomer. Significant contributions to R1 rho-rates from intramolecular motions were found for both isomers. Therefore it is possible to distinguish between at least four conformers interconverting on different time scales based on NMR data and MD refinement. This work shows that thionation is a useful modification of peptides for conformation-activity investigations.

Amino Acid Sequence↗
PubMed1991

Cancer mortality from 1978 to 1987 in smaller regions of Styria, Austria, with different environmental conditions.

In 1984 we have shown in a study, that regions with high air pollution have a higher respiratory cancer rate than regions without substantial air pollution. In this study 45 small regions of Styria, which can be considered homogenous from an environmental viewpoint, have been studied with respect to age standardized respiratory cancer mortality. These small regions have been classified into regions without substantial air pollution, with substantial air and substantial water pollution. Between 1978 and 1987 we have found that small regions with substantial air or water pollution show an increased age standardized respiratory cancer mortality than small regions with "good" environmental conditions. In some regions the rate was twice as high compared to regions without substantial environmental problems. The main difference was found for the age group between 60 and 75 years. Generally between 1978 and 1987 no trend has been observed, only within age groups a shift can be seen.

Adult↗
PubMed1990

Hygienic investigation of coastal waters of the upper Adriatic Sea.

In the course of the bathing season of 1989, investigations of bathing waters were carried out in two-week intervals. From the point of view of public health, the chemical-physical and microbiological results do not suggest objections against bathing at the beach areas investigated (Grado, Lignano). However, these favorable results do not imply intact ecological conditions. National and international standards are designed for humans and allow only very limited conclusions about the living conditions of the marine ecosystem. This also means that ecological investigations are not sufficient to permit conclusions about hygienic conditions. In spite of this seeming contradiction, hygienic and ecological concerns are clearly identical. Hygienic measures must not be limited to local "cosmetic" corrections but must target foremost unfavorable basic conditions.

Enterobacteriaceae↗
PubMed1989

[Testing of industrial repellents against gnats and horseflies].

According to the Austrian Cosmetic Recommendation a minimum period of protection of 2 hours is to be provided. This applies to the preparation on the market with the substance "Merck 3535" in aqueous concentration in the tested area. However, this protection period was not achieved for horseflies. In test trials the characteristic of the individual nuisance should be taken into account.

Alanine↗
PubMed1989

[Air pollution emissions and changes in lung function].

Among the environmental hazards in a modern industrial society, air pollutants are of major significance. They can directly affect the cells of the bronchopulmonary system and lead to an irritation of the epithelial and immunocompetent cells. This results in a decreased secretion of immunoglobulin A, and, consequently, a decreased resistance against infections. Thereby pathogens, especially bacteria, may lead to an inflammation of the respiratory tract. Apart from the direct toxic effect of their pollutants, recurrent inflammations eventually lead to small airway obstruction. The spirometric parameters FVC, FEV1 and MEF50 were reduced. IgA concentration in the saliva was determined by means of immunodiffusion and was found to be reduced when compared to a less exposed group. A series of pathogenic germs were isolated from various mucous membranes (conjunctiva, nose/throat). The median immissions for the children examined were 1.345 mg/m3 SO2 and 0.189 mg/m3 HCl.

Air Pollutants↗
PubMed1989

Bacteriological investigations and resistance patterns in beef and goat's meat in Colombo's slaughter-house.

A high contamination rate was found in meat of slaughtered cattle and goats at the time of this study. Certain organisms were isolated from meat and also from wounds of slaughter workers. A high antibiotic resistance pattern was found - in some instances. Following observations of high surface meat contamination, associated with high antibiotic resistance, it must be assumed, that these highly resistant organisms can also be directly transmitted to humans by transport, transaction and by food preparation. This must be taken into consideration in the actual therapeutics.

Abattoirs↗
PubMed1989

[Epidemiologic significance of sludge for the transmission of zoonoses].

Sludge contains all types of pathogenic organisms originating from the drainage system of the population. Decontamination is difficult and expensive, it is ranging from thermal-chemical to radioactive treatment of the materials. Suitable treatment and use of sludge can really reduce the health hazards to the population.

Animals↗
PubMed1989

Ocular infection investigations in Cairo's waste disposal sites. PVP-iodine treatment trials.

Investigations were carried out in Cairo's waste disposal sites of the inhabitants of all age groups. Germ-spectrum was analyzed before and after PVP-Iodine-treatment. However, any further dilution of PVP-Iodine in the treatment had no effect on the germspectrum, as hydrochloric acid formation in air, produced by plastic burning causes severe eye irritation and a constant lacrimation. The high germ count of the air in the dwellings and the environment is an additional source of contamination to the conjunctiva.

Adolescent↗
PubMed1989

[Serologic studies of listeriosis antibodies in dogs in Greece].

In an epidemiological study of dogs carried out in Greece, antibodies against listeriosis were demonstrated in the slow-agglutination and the complement-fixation-reaction. Depending on the dogs' place of origin CFR titers were found in 6.1% to 51.1%. CFR-titers could be confirmed in a comparative investigation with the slow-agglutination-test.

Animals↗