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Biomedical subjects

V Bauer

Publications and source records attributed to V Bauer.

At least 37 records · Page 2Linked to original sources
PubMed1994

Stobadine-inhibitor of cyclophosphamide-induced micronuclei in mice.

The potential antimutagenic effect of stobadine dipalmitate (STB) on the frequency of micronuclei in reticulocytes of peripheral blood in female ICR mice was studied. The cyclophosphamide model was used to verify this effect. Stobadine dipalmitate was administered orally in three concentrations: STB I, 7.07; STB II, 23.6; STB III, 70.07 mg/kg body wt 2 h prior to or 4 h after (STB II only) cyclophosphamide administration (intraperitoneally, twice 80 mg/kg body wt with a 24 h interval). The method designed by Hayashi et al. [(1990) Mutat. Res., 245, 245-249] was used to prepare and to stain the slides. The results of the experiment show that pretreatment with stobadine 2 h prior to cyclophosphamide administration significantly decreased its mutagenic effect, as manifested by the reduced frequency of micronucleated reticulocytes. This protective effect of stobadine was concentration-dependent with the highest concentration of stobadine inducing the most pronounced decrease of micronuclei. Analysis and identification of the exact mechanism of the protective effects of stobadine is the aim of our further studies.

Animals↗
PubMed1994

[Endothelium and reactive forms of oxygen].

Recent experimental findings suggest that we should now consider some diseases as "endotheliopathies" and some others as "ROS-pathies". The presented review summarizes our knowledge on the role of endothelium and reactive oxygen species (ROS) in physiological processes and diseases. The vascular endothelium provides vital and responsive infrastructure of vessels for the circulation of blood and homeostasis of all organs. Due to its exposure to mechanical, chemical and biological factors, including ROS and the nature of its responses to these insults, it is involved in a wide variety of disease processes. Oxidative stress occurs also in many human diseases. Our understanding of the role played by the endothelium and ROS in disease pathology are still insufficient. To determine if endothelial and ROS-induced changes in hypertension, atherosclerosis, ischemia/reperfusion etc. are the primary cause of specific diseases or merely secondary effects remains to be clarified in several areas from inflammatory processes to cardiovascular diseases. Protection of the endothelium and antioxidant therapy represents a potential successful therapeutic approach in different diseases. In the near future the endothelial and free radical research will surely clarify many of our still unanswered questions.

Animals↗
PubMed1994

Effects of phenylephrine on membrane currents in single smooth muscle cells of taenia caeci.

Procedures used for dissociation of taenia caeci smooth muscle cells usually damage alpha 1-adrenoceptors. This paper describes modes of isolation under which alpha 1-adrenoceptors of taenia caeci do not lose their function. It has been found that antioxidants (dithiothreitol or taurine) are able to protect receptors from injury caused by digestive enzymes. A high concentration of bovine serum albumin also protects receptors from enzyme injury if a relatively specific enzyme (collagenase Type XI, Sigma) is used. Phenylephrine (10 mcmol/l) studied both in muscle strips using the double sucrose gap method and in isolated smooth muscle cells using whole cell current clamp conditions substantially hyperpolarized the smooth muscle membrane. This hyperpolarization was blocked by pretreatment of the tissues or cells by prazosin (1 mcmol/l). Phenylephrine (1-50 mcmol/l), under whole cell patch clamp conditions, enhanced the frequency and amplitude of spontaneous transient outward currents (STOCs), which were voltage- and temperature-dependent, and elicited a low amplitude sustained outward current. Phenylephrine (10 mcmol/l) reduced the inward and enhanced the outward component of the total whole cell current evoked by voltage steps from the holding potential of -50 mV to -10 mV. Under experimental conditions when only calcium current was recorded, phenylephrine significantly enhanced its amplitude. These results are in favor of the assumption that phenylephrine induced hyperpolarization is at least partially the consequence of calcium influx, which activates potassium conductance.

Action Potentials↗
PubMed1993

[Obstructive myocardiopathy and pregnancy].

We report a case of pregnancy in a patient with severe obstructive cardiomyopathy treated with beta-blockers. A review of the literature shows that in spite of possible worsening of the functional symptomatology, pregnancy does not increase the risk of mortality. The recommendations for the conduct of the delivery are reviewed. The risks for the fetus are essentially linked to the treatment with beta-blockers and the possibility of inheritance of the condition.

Adrenergic beta-Antagonists↗
PubMed1993

[Congenital arteriovenous malformation of the internal iliac artery discovered during pregnancy].

We report a case found at the start of labour because of the presence of a "tumour praevia". Ultrasound, Doppler and tomodensitometric examination carried out after caesarean section confirmed the vascular origin of this lesion. Arteriography made it possible to decide the pattern of this arteriovenous malformation which was occurring in several branches of the left internal iliac artery. It was not possible to obliterate it completely by selective arterial embolisation, so it was removed surgically a few months later. Little is known about the complications that occur because of these arteriovenous malformations in pregnancy and during delivery. There is the theoretical risk that spontaneous rupture will occur in pregnancy but this does not justify terminating the pregnancy. It is better to carry out caesarean section because the tumour can obstruct delivery and may rupture as well as causing delay in labour. The treatment for these lesions is sometimes difficult and complex and one has to decide whether to preserve the uterus or not. Selective embolisation and pre-operative embolisation followed by surgical removal of dysplasic tissue are the therapies of choice.

Adult↗
PubMed1993

NANC transmission in intestines and its pharmacological modulation.

Non-adrenergic, non-cholinergic (NANC) nerve stimulation results in excitation (e.j.p., rebound depolarization, contractions) or inhibition (i.j.p., afterhyperpolarization, relaxations) of the gut. NANC neuronal mechanisms participate in the maintenance of the basal tone and spontaneous activity of the gut. There are however species differences, i.e. both NANC excitation and inhibition are present in the guinea pig and only NANC inhibition in the rat intestine. Substance P-like neuropeptide/s are suggested to be mediators released from excitatory NANC and sensory nerves. The latter are activated by histamine and degenerated by capsaicin. There is evidence in favor of a nitric oxide-like substance rather than ATP, dopamine, GABA and neuropeptides (e.g. VIP, PHI/PHM) as the inhibitory NANC mediator in the gut. TTX, high Mg(2+)-low Ca2+ media, 3,4-diaminopyridine, dipyridamol and adenosine deaminase modulate NANC excitation and inhibition. The NANC excitation is more sensitive than the NANC inhibition to the action of catecholamines, reserpine, 6-hydroxydopamine, chymotrypsin, prednisolon, bacitracin, opioids, free oxygen species and low concentration of local anesthetics.

Animals↗
PubMed1991

Role of extra- and intracellular calcium in the contractile action of agonists in the guinea-pig ileum.

The effects of Ca2(+)-channel blockers (nifedipine and verapamil), EGTA, caffeine or the removal of external Ca2+ on the contractile action of different agonists and transmural electrical stimulation were examined in isolated segments of the proximal and terminal part of the guinea-pig ileum. The effects of agonists and nerve stimulation on membrane potential were also studied by means of the sucrose gap method. Acetylcholine-elicited contractions in both parts and noradrenaline- as well as histamine-induced contractions in the terminal part of the ileum were composed of an initial phasic and a sustained tonic component. Single pulse transmural nerve stimulation elicited smooth muscle twitches, whereas addition of CaCl2 to the tissue bath containing Ca2(+)-free and high-K+ medium elicited a sustained contraction. Both verapamil and nifedipine were more potent in inhibiting the tonic phase of the responses to the agonists or CaCl2 than inhibiting the phasic contractions elicited by transmural nerve stimulation, acetylcholine or noradrenaline. The excitatory junction potentials (e.j.p.s.) as well as smooth muscle twitches were reduced only by high nifedipine concentrations. The effects of acetylcholine on membrane potential and input membrane resistance were affected minimally by the omission of extracellular Ca2+, while the contractions gradually disappeared on repetitive agonist application in the absence of external Ca2+ and were blocked by caffeine preexposure. In Ca2(+)-free solution noradrenaline and histamine partially reduced each other's motor effect, while neither of them changed the contractile action of acetylcholine, yet the contraction induced by noradrenaline was prevented and that of histamine significantly reduced by preexposure to acetylcholine.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1991

Angiosarcoma in postsurgical lymphedema. An unusual occurrence in a man.

A 63-year-old man underwent partial left axillary node dissection for metastatic melanoma of unknown primary. Lymphedema of his left upper extremity developed after surgery. Eight years later, extensive cutaneous angiosarcoma developed in the edematous limb. The occurrence of cutaneous angiosarcoma in postsurgical lymphedema is extremely rare in men; to our knowledge, our case is the fifth such case thus far reported.

Arm↗
PubMed1991

Effect of potassium channel blocking agents on the actions of phenylephrine in rabbit taenia caeci.

The effects of tetraethylammonium, apamin, 4-aminopyridine and holding potential on the phenylephrine-evoked outward currents in dispersed smooth muscle cells of the rabbit taenia caeci were analyzed using the whole cell patch clamp method. Phenylephrine (10 mumol/l) under the double sucrose gap condition, substantially hyperpolarized the smooth muscle membrane and reduced the input membrane resistance. This concentration of phenylephrine enhanced the frequency and amplitude of spontaneous transient outward currents (s.t.o.c.s) and elicited a low amplitude sustained outward current which were voltage and temperature dependent. In addition, phenylephrine (10 mumol/l) reduced the outward current evoked by voltage steps. Tetratehylammonium (1-5 mmol/l) attenuated the depolarization-evoked outward current, blocked the appearance of s.t.o.c.s, and fully abolished the phenylehrine induced changes in membrane currents. Apamin (0.1-10 mumol/l) only slightly affected the evoked outward current and s.t.o.c.s. However apamin did not change the phenylephrine-induced outward currents. Pretreatment with 4-aminopyridine (0.5-2 mmol/l) did not reduce the phenylephrine-induced sustained outward current and s.t.o.c.s but prevented the phenylephrine induced reduction of the depolarization-evoked outward current. These results are in favour of assumption that the phenylephrine induced hyperpolarization and reduction in the input membrane resistance are consequences of an enhanced potassium current via tetraethylammonium-sensitive, apamin and 4-aminopyridine resistant potassium channels.

4-Aminopyridine↗
PubMed1990

Effects of phenylephrine in single isolated smooth muscle cells of rabbit and guinea pig taenia caeci.

Spontaneous transient and evoked outward currents were studied using the whole cell patch-clamp technique with freshly dispersed smooth muscle cells isolated from rabbit and guinea pig taenia caeci. Phenylephrine induced a low amplitude sustained outward current in both tissues. Simultaneously, the frequency and amplitude of spontaneous transient outward currents were increased. However, there were differences between the effects of phenylephrine on the evoked outward currents recorded from smooth muscle cells of rabbit (reduction) and guinea pig (enhancement) taenia caeci.

Animals↗
PubMed1990

Effect of stobadine and histamine H1 and H2 blockers on histamine-induced contraction of guinea pig airways in vitro.

Histamine, a nonselective histamine receptor agonist, activates simultaneously both H1 and H2 receptors in the guinea pig trachea and lung strip. The resulting contraction is due to the prevalence of H1 receptors, because they are blocked by the selective H1 antagonist diphenhydramine. The H2 receptor antagonists cimetidine and ranitidine increased the sensitivity of both tissues to histamine by affecting primarily the amplitude of contractions induced by high histamine concentrations. Since the lung strips were more sensitized by ranitidine and low concentrations of the other studied antagonists (diphenhydramine, dithiadene, stobadine) than the tracheal smooth muscle, it is inferred that the density of H2 receptors is higher in peripheral than central airways. From all the studied histamine receptor antagonists only dithiadene was able to unmask the relaxation induced by H2 receptor activation indicative of its highest H1 selectivity. In the light of the concentration-dependent antihistaminic effect of stobadine, i.e. potentiation in low and inhibition in high concentrations, stobadine is suggested to belong to antihistaminics with no histamine receptor subtype selectivity.

Animals↗
PubMed1990

[Invasive cervix cancer stage I and II in women less than 35 years old].

The results of a retrospective study of 74 women under the age of 35, treated invasive cervical cancer, stage I and stage II, between 1973 and 1985, were compared with those obtained in 547 women over 35, treated during the same period of time for a similar cervical cancer. The treatment consisted of: association radium therapy-surgery for stages IB less than 25 mm and II A moderately extended and an association radiotherapy-radium therapy for stages IB greater than 25 mm and II A extended, II B and II C. A better distribution per stage is found in women under 35, identical regarding the histological type with 5-year survival identical in both groups at the same stage. Relapses or recurrences occur much earlier in younger women. In the literature, the age as a prognosis factor is very much controverted. On the contrary, other factors should be taken into consideration: clinical stage, node invasion, size and volume of the tumor, depth of infiltration of the cervix.

Adult↗
PubMed1989

Trachealis responses induced by vincamine and vinpocetine; inhibition by indomethacin and Ca2+ dependence.

Vincamine in low concentrations induced a sustained contraction of the isolated guinea pig trachealis with long latency and slow onset and, in high concentrations, it induced relaxation which was potentiated in the precontracted trachealis. Vinpocetine had actions similar to those of vincamine on trachealis, however its relaxant effect was more pronounced. The vincamine-induced trachealis contraction was not changed by substance P desensitization, was reduced by tetrodotoxin, nifedipine and low Ca2+ high Mg2+ solution and increased in nominally Ca2+-free solution. The vincamine-induced relaxation of precontracted trachealis was increased by guanethidine and was not affected by propranolol, high Mg2+-low Ca2+ solution and tetrodotoxin. Vincamine- and vinpocetine-induced trachealis contraction as well as vinpocetine-induced relaxation at basal tension were abolished by indomethacin. Vincamine in a low concentration shifted to the left the concentration-effect curve for CaCl2 in the K+-depolarized trachealis, and shifted it to the right at a high concentration. Our results indicate that the contractile and relaxant actions of vincamine and vinpocetine on the guinea pig trachealis may be due to the generation of prostaglandins and to changes in the membrane Ca2+ fluxes and/or the intracellular Ca2+ distribution.

Acetylcholine↗
PubMed1989

Calcitonin gene-related peptide action on intestinal circular muscle.

Isolated segments of the guinea pig small intestine were used to examine the effect of calcitonin gene-related peptide (CGRP) on the motor activity of the circular muscle. CGRP (0.3-30 nM) initiated phasic contractions of the circular muscle due to stimulation of cholinergic neurons. Peristalsis, however, was inhibited by CGRP. A further analysis of this effect showed that CGRP had no inhibitory influence on the main, cholinergic, pathway of the ascending enteric reflex (AER) contraction, whereas the hexamethonium- and atropine-resistant pathways of the AER were blocked. The inhibition of the atropine-resistant AER resulted from an action of CGRP on nerves and, since it was antagonized by apamin, might be explained by a CGRP-induced activation of enteric inhibitory neurons. The direct relaxant action of CGRP on the longitudinal muscle was not affected by apamin. These findings indicate a heterogeneity and topical selectivity in the motor actions of CGRP on the gut and suggest that this peptide, when released from nerve endings within the intestine, plays a specific role in the regulation of intestinal motility.

Animals↗
PubMed1989

Interactions of neurogenic responses of longitudinal and circular muscle in the guinea-pig ileum.

The relationship between neurogenic responses of longitudinal and circular muscle was studied by measuring contractions and EMG or nonadrenergic, non-cholinergic (NANC) relaxations and NANC inhibitory junction potentials in different preparations of the guinea-pig ileum. NANC relaxation of longitudinal muscle was observed also without any preceding or concomitant circular muscle contraction ruling out the possibility that the latter might be the cause of the NANC relaxation. Circular muscle twitches or powerful contractions were absent if there was no preceding neurogenic or myogenic excitation of longitudinal muscle; in preparations with myenteric plexus-longitudinal muscle layers removed only small residual responses were seen although still under neurogenic influences. Thus excitation of longitudinal muscle seemed a prerequisite for synchronized and powerful contractions of circular muscle to occur. Cholinergic contraction and NANC relaxation of longitudinal muscle evoked by field stimulation were partly inhibited if the submucous plexus was also present suggesting the involvement of a more complex neuronal circuitry in these responses.

Adenosine Triphosphate↗