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Biomedical subjects

E Simon

Publications and source records attributed to E Simon.

At least 127 records · Page 7Linked to original sources
PubMed1990

Differential osmoresponsiveness of periventricular neurons in duck hypothalamus.

Single-unit responses to osmotic stimulation were recorded extracellularly in slice preparations from the duck's hypothalamus in the periventricular layer (pl), magnocellular center (mc), and deep periventricular neuropil of the paraventricular nucleus (PVN). The pl neurons were located in the dorsorostral third ventricular region of maximum osmoresponsiveness determined in vivo. Hypertonic stimulation (+20 to +35 mosmol/kgH2O) by excess NaCl in the incubation medium excited 25 and inhibited 4 out of 48 pl neurons. Hypotonic (-10 to -20 mosmol/kgH2O) stimulation inhibited 9 out of 10 neurons activated by hypertonic stimulation. Hypertonic activation of pl neurons was maintained in seven out of nine neurons when NaCl was replaced by LiCl, but replacing NaCl by sucrose was ineffective in each of 10 neurons. Synaptic blockade (Ca2(+)-free/high-Mg2+ medium) did not abolish hypertonic activation in 8 out of 11 pl neurons. Among 30 mc neurons, 2 were activated and 1 inhibited by hypertonic stimulation with NaCl (+20 to +35 mosmol/kgH2O), and among 24 neurons in the periventricular neuropil, 2 were activated and 4 inhibited. The function of osmoresponsive pl neurons as specific receptors would be consistent with their morphological characteristics and with the location and functional properties of the duck's third ventricular osmoresponsiveness in vivo.

Animals↗
PubMed1990

[Clinical criteria and evaluation of the pathology and progress of lympho-nodular toxoplasmosis].

We aimed at analysis of the clinical pattern and the course of lympho-nodular toxoplasmosis taking into account the intensity and duration of the illness. Ninety seven patients (69 adults and 28 children) with lympho-nodular toxoplasmosis were examined. Toxoplasmosis was diagnosed by indirect immunofluorescence; the titres of antibodies of IgG and IgM classes were also estimated. Depending on the duration of the illness three periods: early, regression of symptoms and protraction of symptoms were defined; depending on the intensity of signs and symptoms of toxoplasmosis three courses of the disease: acute, subacute and chronic were defined. The analysis showed that clinical picture of lympho-nodular toxoplasmosis was characterized by swelling of various peripheral lymph nodes as well as by general clinical symptoms (88.7% of cases) the intensity and duration of which, to a large extent, determined course of the illness. No correlation between clinical course and duration (early and regression period) of lympho-nodular toxoplasmosis and titres IFA-IgG (before therapy) was found. Pathomorphology of lymph nodes in patients with toxoplasmic lymphadenopathy is a valuable complementary examination which renders it possible to determine the period of the disease.

Adolescent↗
PubMed1990

cdc2/pp56-62 are in vitro substrates for the tyrosine kinase encoded by the v-fms oncogene.

In eukaryotic cells, the serine-threonine-specific kinase cdc2 induces entry into mitosis by phosphorylation of several proteins including cyclin (pp62) with which it forms a tight complex. We show here that cdc2 and several phosphoproteins in the range of 56 to 62 kilodaltons (kDa), associated with cdc2, serve as in vitro substrates for the v-fms-specific tyrosine kinase. This is the first demonstration of in vitro phosphorylation of a physiologically relevant substrate through the v-fms specific kinase. In addition, cdc2 phosphorylated the v-fms polypeptides in serine and threonine residues. The biological significance of the mutual phosphorylations is discussed.

CDC2 Protein Kinase↗
PubMed1989

The common occurrence of furan fatty acids in plants.

The observation that F-acids (1) occur in rat chow initiated a search for F-acids in human diet. We observed that the amount of F-acids with a pentyl side chain in alpha-position taken up with a one-day diet correlates well with the amount of excreted degradation products, the pentyl urofuran acids (2), (3) and (4). Therefore it can be concluded that F-acids with a pentyl side chain are not produced in the human body but are introduced through the diet. The origin of F-acids carrying an alpha-propyl side chain is less clear. The amount of propyl-urofuran acids (2) and (3) excreted in urine was found in one case out of three to be five times higher than the amount of F-acids carrying a propyl group in alpha-position taken up by the diet. Therefore, it can presently not be excluded that a portion of the propyl F-acids is produced by the body. F-acids found in human food are mainly introduced into the body by vegetables and fruits. F-acids were found also in birch leaves in considerable amounts, as well as in grasses, dandelion and clover leaves. Thus, we can conclude that F-acids are common constituents of plants.

Chromatography, Gas↗
PubMed1989

Role of Calcium in Phytochrome-Controlled Nyctinastic Movements of Albizzia lophantha Leaflets.

The involvement of Ca(2+) on phytochrome-controlled nyctinastic closure in Albizzia lophantha has been studied by testing the effect of the calcium ionophore 6S-[6alpha(2S(*),3S(*)),8beta(R(*)),9beta,11alpha]-5- methyl-amino)-2-[[3,9,11-trimethyl-8-[-1-methyl-2-oxo-2-(1H-pyrrol-2-yl) ethyl]-1,7-dioxaspiro[5.5]-undec-2yl] methyl]-4-benzoxazolecarboxylic acid (A23187) and the intracellular calcium antagonist 8-(diethylamino)octyl 3,4,5-trimethoxybenzoate hydrochloride (TMB-8). An external supply of Ca(2+) or calcium ionophore A23187 to the Albizzia leaflets emulates the effect of red light irradiation and counteracts the inhibitory effect of far red light. The intracellular calcium antagonist TMB-8 supplied to Albizzia leaflets inhibits the effect of red light, but had no effect on far red irradiated plants. This suggests a dependence between phytochrome action and intracellular free Ca(2+). We suggest that calcium acts as a phytochrome messenger on control of ion fluxes that drive turgor changes in pulvinular motor cells.

Journal Article↗
PubMed1989

Role of angiotensin II in aldosterone regulation in the Pekin duck.

The response of plasma aldosterone to increased plasma angiotensin II (AII) was evaluated in normally hydrated Pekin ducks as well as in birds in which plasma sodium had been acutely increased (+12 mmol/l) or reduced (-4 mmol/l) by the prior infusion of hypertonic saline or hypotonic glucose. In all cases, the i.v. infusion of AII at rates of 5, 15 and 45 pmol/kg per min for 1 h produced dose-dependent increases in the plasma concentration of aldosterone, with a potency that was inversely related to the sodium status. In addition, adrenal receptors for AII were demonstrated by in-vitro autoradiography and membrane-binding techniques, suggesting that the AII effect on aldosterone secretion is direct. Angiotensin II produced no change in plasma corticosterone. The infusion of KCl at 1, 2 and 5 mmol/l for 1 h increased plasma potassium by as much as 2 mmol/l, but had no influence on plasma aldosterone. Similarly, the heptapeptide angiotensin III, infused at 5, 15 and 45 pmol/kg per min for 1 h had no effect on circulating aldosterone. The results show that in ducks, AII has a physiological role in the control of aldosterone, whereas plasma potassium and angiotensin III have no such secretagogue function.

Adrenal Glands↗
PubMed1989

[Normal frequency jet ventilation using a nitrous oxide-oxygen mixture (NFJV/SoSG) for microlaryngoscopy and endolaryngeal microsurgery: performance of the Dresden apparatus system, results of experimental purposes and clinical tests and comparison with other jet technics].

Presentation of intentions and devices for normofrequency jet-ventilation using N2O/O2-mixture (NFJV/SoSG). Exclusion of Venturi principle permits application of N2O/O2 to anaesthetic ventilation. The conduction of narcosis is analogous to the usual combination anaesthesia. Further advantages of method: Efficient ventilation and oxygenation (F1O2 = 0.25...0.33); minimal need of space for ventilating system; optimal and variable working conditions for the endoscopist; small economic expense. In case of undisturbed gas backflow are hazardous peak pressures excluded. In comparison with ventilation using Carden tube or HFPPV/pneumatic valve principle the NFJV/SoSG appears at the very least equivalent; in important points (need of space at small tracheal diameters; tracheal stenosis) NFJV/SoSG is superior these methods.

Anesthesia↗
PubMed1989

Location and functional properties of angiotensin targets in the third ventricular region.

Centrally mediated effects of angiotensin II (ANG II) in salt and fluid balance of birds were analyzed by: 1. observing physiological responses, 2. identifying putative targets, 3. recording neuronal activity, and compared with corresponding data obtained in mammals. ANG II responsive systems inside and outside the blood-brain-barrier of the hypothalamic region could be characterized in birds as spatially and functionally separate from both central nervous osmoreceptive and neuroendocrine functions in salt and fluid balance. Morphological and functional criteria were consistent in supporting the dual function of ANG II as a physiological systemic messenger to and an intrinsic messenger within the brain.

Angiotensin II↗
PubMed1988

Occlusion of rostroventral 3rd ventricle abolishes drinking but not AVP release in response to central osmotic stimulation.

Dogs were implanted with a device for chronic cannulation of the anterior part of the 3rd ventricle (A3V). Intracerebroventricular (i.c.v.) infusion of artificial cerebrospinal fluid (CSF) containing 0.35 M NaCl into the A3V of 7 normally hydrated dogs induced thirst (average water intake 11.8 +/- 2.0 ml.kg-1 b. wt.) and significantly increased arginine-vasopressin (AVP) concentration in the blood plasma from 3.4 +/- 0.3 to 8.2 +/- 1.2 pg.ml-1. When repeating the i.c.v. hypertonic infusion at intervals of one week or more in two dogs, its dipsogenic effect vanished within 3-5 months. X-ray analysis revealed an occlusion of the rostroventral part of the A3V. Subsequent controls on 3 other dogs confirmed that the dipsogenic response to i.c.v. osmotic stimulation was abolished in association with similar partial occlusions of the A3V. However, this stimulus still produced a significant increase of plasma AVP from 3.7 +/- 0.5 to 5.7 +/- 0.7 pg.ml-1 in the 5 dogs. Control of drinking in these dogs was otherwise unimpaired as indicated by their normal plasma osmolalities. Histological examination revealed that the loss of the dipsogenic response to i.c.v. infusion of 0.35 M NaCl was in each case associated with fibrinous occlusion of the A3V between its rostral wall and the mass intermedia, preventing the passage of the infusate to the supraoptic and infundibular recesses.

Animals↗
PubMed1988

Thermal characterization and transmitter analysis of single units in the preoptic and anterior hypothalamus of conscious ducks.

With a multibarrel assembly combining one carbon fiber micropipette as recording electrode and 6 pipettes for microiontophoretic application of drugs, the activity of neurons in the preoptic and anterior hypothalamic (POAH) region was extracellularly recorded in situ in conscious ducks implanted chronically with a device permitting hypothalamic thermal stimulation. Among 355 neurons 17% were identified as warm-responsive (warm units) and 20% as cold-responsive (cold units). In 58 warm and 56 cold units control discharge rates at 40 degrees C local temperature (F40) and temperature coefficients (delta F/delta T) were determined and presented as means +/- SEM. The F40 values of warm units (35.2 +/- 2.3 Imp . s-1) were significantly higher than of cold units (16.3 +/- 1.8 Imp . s-1). The delta F/delta T values (+1.77 +/- 0.15 and -1.77 +/- 0.19 Imp . s-1 . degree C-1) of warm and cold units were not different in absolute terms. In pilot experiments either activation or inhibition by lowering whole-body temperature was observed in both warm and cold units. Microiontophoretic application of one or more of the amines acetylcholine (ACh), 5-hydroxytryptamine (5-HT), and noradrenaline (NA) to warm and cold units revealed differences in their responsiveness to ACh, which more consistently stimulated cold units. NA inhibited the majority of warm units; 5-HT stimulated the majority of cold units. In both warm and cold units NA and ACh differed in their actions, with the latter amine more consistently producing activation.

Animals↗
PubMed1988

Changes in water balance and in release of arginine vasopressin during thermal adaptation in guinea-pigs.

The following experiments were made to investigate whether any changes in water balance and in the release of arginine vasopressin (AVP) accompany the development of thermal adaptation. Twelve guinea-pigs (300-400 g initial weight) were kept in individual metabolic cages at 22 degrees C during weeks 1 and 5. During weeks 2-4, six of them were exposed to 5 degrees C, and six to 28 degrees C. Before the start of the experiment, eight animals were implanted with chronic arterial catheters for removal of blood samples. Food and water intake, body weight, and colon temperature, as well as the amounts of urine and feces, were recorded in each animal every morning. In urine and blood plasma samples (taken daily, resp. weekly), the osmolality was estimated by vapor pressure osmometry, and concentrations of AVP by a radioimmunoassay. It is apparent that the daily turnover of water increased from 94 ml in guinea-pigs adapted to 22 degrees C (N), to 111 ml in cold adapted (CA), and to 154 ml in warm adapted (WA) animals. In CA the amounts of AVP excreted in urine increased dramatically (being 10 times higher than in WA). This high release of AVP cannot be explained by changes in osmotic pressure and by alterations in volume of extracellular fluid. It is concluded that AVP is released in CA guinea-pigs mainly as a stressor hormone, in amounts which highly exceed the antidiuretic needs. The WA animals, having free access to water, did not use the AVP system to conserve water. They doubled their water intake, producing more urine of lower osmolality, corresponding to the reduced release of AVP.

Adaptation, Physiological↗
PubMed1988

Central and systemic antidiuretic hormone and angiotensin II in salt and fluid balance of birds as compared to mammals.

1. Tonicity dominates the release of ADH with similar sensitivities (0.2-1 pg/ml per mOsm/kg) for both birds and mammals. 2. There is an inverse relationship between the volume of the extracellular fluid compartments and the plasma level of ADH. 3. Angiotensin II formation is governed by volume factors. 4. In birds the factors reducing the delivery of Na+ to the nephron distal tubules stimulate ANGII formation. 5. Mammals have a high vascular constrictor sensitivity to ADH and ANGII; there is little or no vascular sensitivity to these in birds. 6. In birds and mammals the subfornical organ and other circumventricular organs have receptors that specifically bind ANGII. 7. Dog and duck CSF levels of ADH and AII indicate their function as specific mediators of intrinsic neuronal systems controlling salt and fluid balance.

Angiotensin II↗
PubMed1988

An immunochemical assay for natural IgM antibodies with an affinity to galactose and whose titer is reduced in the sera of cancer patients.

Normal sera contain an IgM fraction which binds to free galactosyl groups of agarose. This fraction causes complement-dependent lysis of Ehrlich ascites tumor cells (EATC). Cancer sera show a much reduced titer of this lytic activity. In this paper we describe an immunochemical assay for these galactophilins (GALF). Agarose columns were immunoabsorbent and bound proteins were detected by labeled antibody to human IgM. All 157 normal sera contained GALF. The serum GALF concentrations of normal sera were linearly correlated to the serum cytolytic titers. However, EATC absorbed only 15% of normal serum GALF. The titers in normal females are higher than in males. The titers in 147 nonmalignant chronic disease patients were lower than the normals only in women over 40 years of age. The sera of 138 cancer patients, taken before any therapy, were significantly lower than the corresponding normal or chronic disease controls. Lymphoproliferative neoplasms were associated with the lowest titers while melanoma sera showed normal titers. It is likely that GALF is bound to tumor associated antigens with free galactosyl groups. These are on the cell surface and/or are shed into the circulation. GALF titration may prove useful in following treatment efficacy in individual cancer patients.

Adult↗
PubMed1988

Vasoactive intestinal peptide stimulates blood flow and secretion of avian salt glands.

The neuromodulatory role of vasoactive intestinal peptide (VIP) in avian salt gland secretion and blood flow was investigated in conscious saltwater-acclimated Pekin ducks. Glandular blood flow was measured by laser-Doppler flowmetry or the radioactive microspheres technique. Osmolal excretion was closely related to salt gland blood flow during salt loading. At threshold conditions of salt gland secretion, VIP infused intracarotidally induced both osmolal excretion and arteriolar vasodilation dose dependently (30-240 pmol.min-1.kg body wt-1). The VIPergic effect on the secretory process for NaCl was enhanced by simultaneous intracarotid application of acetylcholine (5 nmol.min-1.kg body wt-1), whereas the intrinsic vasodilatory potency of acetylcholine appeared to be nonadditive in coinfusion experiments. Ongoing secretion induced by systemic infusion of hypertonic saline could be suppressed by muscarinic antagonists, with salt gland blood flow being sustained at the reduced level of atropine-resistant vasodilation. Subsequent intracarotid infusion of VIP stimulated glandular blood perfusion and also, to a minor extent, osmolal excretion, suggesting an independent, functional VIP system in efferent salt gland control.

Acclimatization↗