Biomedical subjects

E Chifu

Publications and source records attributed to E Chifu.

5 recordsLinked to original sources

PubMed1995

[Management of epidural anesthesia in a patient with aortitis syndrome].

We report an anesthetic management of a patient with severe vascular occlusion case caused by Aortitis syndrome. The patient, 61 yr-old woman, was scheduled for sigmoidectomy. Her bilateral common carotid arteries and left main coronary artery were totally occluded, but she had been asymptomatic for over thirty years. Epidural anesthesia was chosen to provide pain control, cardiovascular stability, and also to maintain consciousness during operation for cerebral circulatory evaluation. Following intravenous administration of lactated Ringer's solution (about 1000 ml), epidural blockade was maintained with 1 to approximately 1.5% lidocaine and butorphanol. Our findings in this case indicate that it is important for coronary and cerebral perfusion to have normal central venous pressure (preload) and arterial pressure during sympathetic blockade resulting from epidural anesthesia.

Adenocarcinoma↗

PubMed1992

Monolayer properties of archaeol and caldarchaeol polar lipids of a methanogenic archaebacterium, Methanospirillum hungatei, at the air/water interface.

Monolayer studies at the air/water interface were carried out on the major tetraether (caldarchaeol-) derived phosphoglycolipid, Glcp-alpha(1-2)-Galf-beta(1-1)-caldarchaeol-phosphoglycerol (PGC-I), the major diether (archaeol-) derived glycolipid, Glcp-alpha(1-2)-Galf-beta(1-1)-archaeol (DGA-I), the major archaeol-derived phospholipids, phosphatidyl-N,N dimethylaminopentanetetrol (PPDAA) and phosphatidyl-N,N,N-trimethylaminopentanetetrol (PPTAA) and the minor caldarchaeol-derived glycolipid, Glcp-alpha(1-2)-Galf-beta(1-1)-caldarchaeol (DGC-I) isolated from the methanogenic archaebacterium, Methanospirillum hungatei. The compression isotherms obtained showed that the two tetraether lipids had molecular surface areas about twice those of the diether lipids at all surface pressures, suggesting that both polar headgroups of the tetraether lipids are anchored into the aqueous subphase, even at the collapse pressure pi c. A U-shaped hydrocarbon chain conformation thus appears to be preferred for the tetraether lipids at the air/water interface, rather than an extended chain arrangement. The compression isotherms of the two tetraether lipids PGC-I and DGC-I were very similar at pH 0, both molecules being uncharged, but at pH 5.6 or 8, PGC-I films were much more expanded than the neutral DGC-I, due to ionization of the phosphate group in PGC-I and the resulting charge-charge repulsion. Monolayers of the zwitterionic diether phospholipids PPDAA and PPTAA were much less compressible than the glycosylated lipids, PGC-I, DGC-I and DGA-I, because the latter lipids contain the more compressible diglycosyl headgroup, oriented in horizontal conformation at low surface pressures, compared to the lower compressibility of the zwitterionic headgroup in the vertical conformation, particularly at pH 0 and 5.6.(ABSTRACT TRUNCATED AT 250 WORDS)

Air↗

PubMed1990

Influence of stearic acid monolayers upon the procaine adsorption from underlying alkaline aqueous solutions.

Adsorption of procaine at the air/water interface and its penetration into stearic acid monolayers from aqueous subphase of pH 8 are studied by measuring surface tension of aqueous procaine solutions and by recording surface pressure vs. mean molecular area curves for stearic acid monolayers spread onto procaine solutions of different concentrations. The amount of procaine in the interface is derived by means of Gibbs' equation. Results are compared to those obtained earlier at pH 2 and on unbuffered subphases. With increasing pH an increasing procaine adsorption and procaine penetration is observed. This phenomenon is interpreted in terms of protolytic equilibria in which participate both surfactants procaine and stearic acid.

Adsorption↗

PubMed1987

Intermolecular interactions in lipid/carotenoid monolayers.

The collapse pressure at the air-water interface of monomolecular films of 1,2-distearoyl derivatives of phosphatidylcholine and digalactosyldiacylglycerol containing various proportions of the carotenoid astaxanthin was related to the composition of the monolayer. The results were analysed by using a regular-association approximation by which it is assumed that there is a stepwise formation of ABi-type associations where A and B represent the diacyl lipid and astaxanthin respectively and 1 less than or equal to i less than or equal to 6. This treatment provides an adequate description of the experimental data and permits calculation of equilibrium constants for the steps in complex-formation; each step is said to have the same equilibrium constant. The value for the collapse-surface-pressure increment associated with formation of ABi complexes was also derived. Calculated values of equilibrium constants and collapse-surface-pressure increments are greater for phosphatidylcholine/astaxanthin mixed monolayers than for digalactosyldiacylglycerol/astaxanthin mixed monolayers. These differences are discussed in terms of intermolecular interactions between components in the two systems.

Carotenoids↗

PubMedDate not supplied

Surface complexes of xanthophyll films with transition metal ions.

Compression isotherms of astaxanthin (AX; 3,3'-dihydroxy-4,4'-dioxo-beta-carotene) monolayers, recorded at the air/water interface show, on the one hand, the collapse pressure to depend on the subphase pH, indicating the ionisation of AX at high pH values, and on the other hand, the subphase Co2+ ions to have a condensing effect upon the monolayer and to entail the increase of its collapse pressure. The latter effects are assigned to surface complex formation. The interfacial tension at the benzene/water interface (the benzene phase containing AX, the water phase Co2+ ions) exhibit a maximum at a molar ratio AX: Co of about 3.6, pleading for the formation of relatively stable Co(AX)4 type interfacial complex. Geometric model and ligand field considerations show besides the dative type sigma-bond formation, the possibility of both dative and retrodative type pi-bond formation between Co2+ and the AX ligands. Under the working conditions used, the formation of a neutral non-electrolyte type complex of the composition [Co(LH)2L2] is postulated, where LH stands for the neutral AX molecule, L- for its anion.

Air↗