Biomedical subjects

G Ebert

Publications and source records attributed to G Ebert.

18 recordsLinked to original sources

PubMed2005

Identification of potent odorants in different cultivars of snake fruit [Salacca zalacca (Gaert.) Voss] using gas chromatography-olfactometry.

Three cultivars of snake fruits, Pondoh Hitam, Pondoh Super, and Gading, were freshly extracted using liquid-liquid extraction. The aroma compounds of the three samples were analyzed by GC-MS and GC-olfactometry using the nasal impact frequency (NIF) method. A total of 24 odor-active compounds were associated with the aroma of snake fruit. Methyl 3-methylpentanoate was regarded as the character impact odorant of typical snake fruit aroma. 2-Methylbutanoic acid, 3-methylpentanoic acid, and an unknown odorant with very high intensity were found to be responsible for the snake fruit's sweaty odor. Other odorants including methyl 3-methyl-2-butenoate (overripe fruity, ethereal), methyl 3-methyl-2-pentenoate (ethereal, strong green, woody), and 2,5-dimethyl-4-hydroxy-3[2]-furanone (caramel, sweet, cotton candy-like) contribute to the overall aroma of snake fruit. Methyl dihydrojasmonate and isoeugenol, which also have odor impact, were identified for the first time as snake fruit volatiles. The main differences between the aroma of Pondoh and Gading cultivars could be attributed to the olfactory attributes (metallic, chemical, rubbery, strong green, and woody), which were perceived by most of the panelists in the Pondoh samples but were not detected in the Gading samples. This work is a prerequisite for effective selection of salak genotypes with optimal aroma profiles for high consumer acceptance.

Arecaceae↗

PubMed1998

Concentrations and decay rates of ozone in indoor air in dependence on building and surface materials.

The decay of ozone in indoor air was measured in a closed chamber after contact with different building materials and residential surfaces. The tested materials were: vinyl wall paper, woodchip paper, plywood, latex paint, fitted carpet, and plaster. In the summer of 1996, the entry of ozone from ambient air into indoor air during ventilation and the ozone decay in indoor air, after windows had been closed again, were studied. Measurements were done in a residential house on the outskirts of Berlin. The following results were gained: the chamber measurements showed a decay of ozone after contact with most of the materials put inside the chamber. Higher decay rates have been obtained for wall papers, plywood, fitted carpet and plaster. As described in the literature, ozone is able to react with olefines inside the materials and is able to form formaldehyde and other components. This formation of formaldehyde could also be confirmed in our investigations. Thus, in most cases, the formaldehyde concentrations were lower than the German guideline value of 0.1 ppm. The formation of formaldehyde could be prevented when a special wall paper that was coated with activated carbon was used. In the house, a complete ozone diffusion into indoor air took place during ventilation within 30 min. After closing the windows, the ozone concentrations decreased to the basic level before ventilation within 60-90 min.

Air Pollution, Indoor↗

PubMed1996

Indoor air pollution by different heating systems: coal burning, open fireplace and central heating.

Investigations of indoor air pollution by different heating systems in private homes are described. Sixteen homes, 7 with coal burning, 1 with open fireplace (wood burning) and 8 with central heating have been investigated. We measured the concentrations of carbon monoxide, carbon dioxide and sedimented dust in indoor air, of total suspended particulates, heavy metals and of polycyclic aromatic hydrocarbons in indoor and outdoor air. Measurements were taken during winter (heating period) and during summer (non-heating period). Generally, we found higher indoor air pollution in homes with coal burning and open fireplace than in homes with central heating. Especially, the concentrations of carbon monoxide, sedimented dust and of some heavy metals were higher. In one case, we found also high indoor air pollution in a home with central heating. This apartment is on the ground floor of a block of flats, and the central heating system in the basement showed a malfunctioning of the exhaust system.

Air Pollutants↗

PubMed1990

[Report of experiences with fibrinolytic therapy of deep venous thrombosis of the legs].

It is reported on the fibrinolytic therapy of thrombosis of the deep veins of the legs, the pelvis and the arms. This treatment was analysed in 18 patients who were treated between 1983 and 1986. The possible causes of the development of thrombosis, such as ovulation inhibiting drugs and the postoperative state, are mentioned. Fibrinolysis was performed with streptokinase (awelysin) and urokinase (ukidan). In 11 patients streptokinase infusions therapy in ultra-high doses was carried out. Within 6 hours and 30 minutes the patients got 9.500,000 units of streptokinase. The complications of the streptokinase treatment are discussed. According to the age of the phlebothrombosis and the control phlebography 2 groups of patients were formed. In the first group including thromboses lasting for 1-6 days, 7 patients showed a complete recanalisation. In the second group including thromboses lasting for 1-3 weeks, only 4 patients developed complete recanalisation. The remaining patients had only a partial recanalisation. The post-lysis effect is stressed. Streptokinase therapy with ultra-high doses has become the standard procedure of fibrinolysis treatment in our hospital.

Adolescent↗

PubMed1986

Conformations of hydrophobic polyelectrolytes.

Recent studies on the (hypercoiled) compact conformation and the pH-induced conformational transition to the extended coil of the hydrophobic poly(acids or bases), which have been well used in industrial and medical circles, are summarized, especially on the basis of our studies on poly(alpha-alkyl acrylic acids) and maleic acid copolymers with hydrophobic aromatic monomers. The stability of the compact conformation and values of various thermodynamic parameters of the transition of the hydrophobic polyelectrolytes suggest the importance of hydrophobic interaction among the side chains to form the compact conformation. Characterization of various physicochemical methods, including 1H-NMR measurements, gives a model of the compact conformation with a more expanded structure than in globular proteins, a free-draining property of the solvent, the conformation fluctuation, etc. Also, the apparent two-state character of each segment in the transition region, a life-time in each state and the cooperative parameter for the compact form formation are discussed. A review of our conformational studies on the hydrophobic-hydrophilic polypeptides is also given. For the anion-induced conformation transition in basic homopoly(alpha-amino acids), hydrophobic characters of the anion and the side chain in the polypeptide are shown to be important, especially in terms of solvation. The difference in the induced conformation by the anion between random and alternating basic copolypeptides is explained by introducing a model which shows the importance of the sequence of hydrophobic and hydrophilic residues in the polypeptide to induce the ordered conformation of the anions. Also, we attempt to explain the difference between the induction of ordered conformation in the basic homo- or copolypeptide in reversed micelles with a large sulfonate (AOT) vs. that in aqueous AOT in terms of the hydrophobic character of the side chains in the polypeptides, AOT and the medium.

Electrolytes↗

PubMed1977

On the introduction of disulfide crosslinks into fibrous proteins and bovine serum albumin.

Hydroxyl groups in serine side chains of collagen, silk fibroin, and bovine serum albumin (BSA) were converted to SH by tosylation. In collagen film, 50% of the serine OH groups could be thiolated at most. In fibroin, only 13% because of its compact beta-pleated sheet structure and low susceptibility to swelling. The SH groups introduced are near enough together to form -S-S- bonds by oxidation. The residual SH content after oxidation was 0.1% in collagen and 0.03 to 0.25% in fibroin. Disulfide crosslinking increased the shrinkage temperature of collagen and fibroin and decreased the amount of shrinkage. BSA was crosslinked to dimers (MBSA) according to gel permeation chromatography and sedimentation analysis by the analytical centrifuge. Because these crosslinked proteins can be metabolized by the usual processes, in contrast to those crosslinked by artificial, nonphysiological bridges, they may be used for biological or medical purposes.

Amino Acids↗

PubMed1977

The formation and cleavage of lysinoalanine crosslinks.

Treatment of lysinoalanine (LAL) with methyl iodide at pH-values above 8 leads to cleavage to dehydroalanine (DHA) and Nepsilon-di- or/and trimethyllysine, as was shown by ultraviolet spectra and amino acid analysis. This reaction is due to methylation of the crosslinking NH group of LAL to the quaternary ammonium compound; nucleophilic beta-elimination follows. By this reaction, the epsilon-amino groups of polylysine and its copolymers can be methylated to form di- and/or trimetryl-lysine residues. Chemically modified polypeptides containing Nepsilon-dimethyllysine can be made in this way.

Alanine↗

PubMed1977

On the specific cleavage of cysteine containing peptides and proteins.

Addition of cysteine to the double bonds of polydehydroalanine and copolymers of dehydroalanine (DHA) and methylcysteine, alanine, leucine or gamma- methyl-L-glutamate is accompanied by increased solubility and decreased molecular weight. This result is due to a peptide bond cleavage caused by formation of a thiazolidine as a consequence of nucleophilic attack by the sulfur atom on the preceding C=O group and subsequent splitting of the peptide bond by nucleophilic attack of an OH ion. This mechanism is predominant in alkaline media; in acid another mechanism is favoured; carbonyl-oxygen attacks the carbonyl-C-atom of the cysteine residue, forming a second ring system. Addition of one water molecule then yields two peptide fragments, one of them a terminal cysteine residue. Both mechanisms could be confirmed in the case of gamma-L-glutamyl-dehydroalanyl-glycine by adding cysteine. Furthermore, it could be shown that SH-glutathione is decomposed at alevated temperatures according to the two mechanisms mentioned. This SH-induced peptide bond cleavage can be used for selective peptide chain splitting of cysteine-containing polypeptides and proteins under relatively mild conditions.

Alanine↗

PubMed1976