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Biomedical subjects

K Ivanova

Publications and source records attributed to K Ivanova.

33 records · Page 2Linked to original sources
PubMed1988

Amiloride increases the sensitivity of particulate guanylate cyclase to atrial natriuretic factor.

The natriuretic agent amiloride induces a shift of the dose-response curve of particulate guanylate cyclase to atrial natriuretic factor (ANF) to the left. The ANF concentration for half-maximal activation of guanylate cyclase is shifted from 20 to 3 nM in the presence of 100 microM amiloride. This effect is observed with GTP*Mn2+, but not with GTP*Mg2+ as substrate. Amiloride derivatives, which inhibit a specific Na+-channel, also shift the dose-response curve to the left. These data suggest that some of the effects of amiloride may be mediated by an increased sensitivity of particulate guanylate cyclase to ANF.

Amiloride↗
PubMedDate not supplied

Bilophila wadsworthiain brain abscess: case report.

A case of a patient with a 20-year history of chronic otitis media complicated by cholesteatoma and brain abscess is described. A CT scan with contrast material showed three abscess cavities in the right cerebellar hemisphere. A culture from a specimen of the cholesteatoma yielded a significant amount of growth of Bilophila wadsworthia, Bacteroides fragilis and Prevotella oris and a moderate growth of alpha-streptococci and Staphylococcus simulans. From the pus of the brain abscess we also isolated numerous Bilophila wadsworthia, Bacteroides fragilis and Prevotella oris and some Prevotella buccae and Peptostreptococcus anaerobius. No aerobes were present. The patient underwent a craniotomy and the biggest abscess was removed together with the capsule. The antimicrobial therapy included penicillin plus metronidazole and later augmentin. The result of the treatment was a complete cure and total recovery of the patient. This is the first documentation of isolation of B. wadsworthia in chronic otitis media and in brain abscess.

Journal Article↗
PubMedDate not supplied

Gravity perception and signal transduction in single cells.

Cellular signal processing in multi-, as well as in unicellular organisms, has to rely on fundamentally similar mechanisms. Free-living single cells often use the gravity vector for their spatial orientation (gravitaxis) and show distinct gravisensitivities. In this investigation the gravisensitive giant ameboid cell Physarum polycephalum (Myxomycetes, acellular slime molds) is used. Its gravitaxis and the modulation of its intrinsic rhythmic contraction activity by gravity was demonstrated in 180 degrees-turn experiments and in simulated, as well as in actual, near-weightlessness studies (fast-rotating clinostat; Spacelab D1, IML-1). The stimulus perception was addressed in an IML-2 experiment, which provided information on the gravireceptor itself by the determination of the cell's acceleration-sensitivity threshold. Ground-based experiments designed to elucidate the subsequent steps in signal transduction leading to a motor response, suggest that an acceleration stimulus induces changes in the level of second messenger, adenosine 3',5'-cyclic monophosphate (cAMP), indicating also that the acceleration-stimulus signal transduction chain of Physarum uses an ubiquitous second messenger pathway.

Acceleration↗
PubMedDate not supplied

[Fluorine content in natural cow milk from the region of Plovdiv].

Fluorine content in natural cow milk has been determined with a view to the fluoration of the milk and its use for dental caries prophylaxis. Fluorine has been determined by the method of standard calibration, making use of fluorine selective electrode and "Orion SA 720 pH/ISE Meter" with LCD display. The mean fluorine quantity in milk is mean = 0.046 ppm, being far lower than the optimal fluorine concentration.

Animals↗