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Biomedical subjects

E Simon

Publications and source records attributed to E Simon.

At least 145 records · Page 8Linked to original sources
PubMed1987

Gradient of arginine vasopressin concentration but not angiotensin II concentration between cerebrospinal fluid of anterior 3rd ventricle and cisterna magna in dogs.

Dogs were chronically implanted with two devices for cerebrospinal fluid (CSF) sampling from (a) the anterior part of the 3rd ventricle and (b) the cisterna magna. In conscious dogs arginine vasopressin (AVP) concentration of CSF samples collected at different occasions were 2-3 times higher in the CSF of the 3rd ventricle as compared to the AVP concentration of the cisterna magna. Inhalation anesthesia stimulated AVP release into the CSF at both sites by a factor of about 2, the gradient between 3rd ventricle and cisterna magna CSF of 2-3 remained for AVP in simultaneously collected samples. In contrast, angiotensin II-like immunoreactivity of CSF was not significantly different at both sites, neither in the conscious dogs nor during anesthesia. It is concluded that the main amount of AVP enters the CSF at the 3rd ventricular level.

Angiotensin II↗
PubMed1987

Autoradiographic localization and characterization of circumventricular angiotensin II receptors in duck brain.

Binding of [125I-5Val]angiotensin II and [125I-1Sar, 8Ile]angiotensin II to target sites in the hypothalamus of the Pekin duck was determined by quantitative receptor autoradiography and conventional membrane binding techniques. Circumventricular areas involved in body fluid homeostasis like the subfornical organ (SFO), median eminence and the anterior-ventral region of the third ventricle showed highest labeling density. Binding sites for angiotensin II were also found in the paraventricular and supraoptic nuclei. The physiological relevance of the labeled SFO angiotensin II receptor is indicated by similarities between rank orders of potency of angiotensin II analogues in displacing radiolabeled ligands and their physiological osmoregulatory potencies. Receptor density in the SFO of saltwater-acclimated ducks was increased 3-fold compared to non-acclimated freshwater ducks, indicating an up-regulation of the angiotensinergic system in ducks under conditions of dehydration or high salt intake.

Animals↗
PubMed1987

Comparison between hypothalamic thermoresponsive neurons from duck and rat slices.

Neuronal thermoresponsiveness in the preoptic and anterior hypothalamic (PO/AH) region of a bird and a mammal were compared in vitro by recording the activity of 48 units from ducks and 37 units from rats in tissue slices subjected to temperature changes. Warm-responsive units were found in similar proportions in duck and rat PO/AH slices. The average degrees of thermoresponsiveness did not differ between the two species. Neurons exhibiting thresholds of warm responsiveness had higher threshold temperatures (2P less than 0.01) in duck (38.8 +/- 0.2 degrees C) than in rat (37.4 +/- 0.4 degrees C) slices (means +/- standard errors). Firing rates at threshold temperatures and thermoresponsiveness below and above thresholds did not differ between ducks and rats. During synaptic blockade in a Ca2+-free/high-Mg2+ medium, warm-responsiveness was retained in 9 out of 13 units in duck slices and in 8 out of 13 units in rat slices. In two instances in ducks and in one case in rats positive temperature coefficients were converted into negative temperature coefficients. Among two cold-responsive units tested in duck slices one retained its cold-responsiveness. It is concluded that in vitro evaluation of PO/AH neuronal thermoresponsiveness in a bird and a mammal has not revealed differences at the single unit level which might explain the diverging contributions of the avian and mammalian hypothalamus to deep body temperature perception.

Action Potentials↗
PubMed1987

Effect of bombesin on thermoregulation of the rabbit.

Injections of bombesin (BOM, 125, 250 and 500 ng) into the preoptic/anterior hypothalamus caused dose-related decreases of threshold temperatures for metabolic cold defence, cutaneous vasomotor tone and respiratory rate, combined with a reduced sensitivity of these thermoregulatory effectors in response to core temperature changes induced at thermoneutral or warm ambient conditions. Intracisternal (i.c.) injections of BOM (250 ng) produced qualitatively identical thermoregulatory effector changes in response to core temperature changes. Injections of BOM into the posterior hypothalamus did not affect body temperature control. Increased locomotor behavior, licking and grooming was elicited, however, from all injection sites. The results explain the prevailing hypothermic effect of BOM as the consequence of the concerted decrease in threshold temperatures and "gains" of all autonomic thermoregulatory effectors and suggest the activation of warm inputs, relative to cold inputs, at the hypothalamic level as the underlying mechanism. Direct or indirect inhibition of the intrinsic hypothalamic system involving thyrotropin-releasing hormone (TRH) and consequent deactivation of central noradrenergic pathways known to generate the entire autonomic pattern of cold defence might be involved in the neuro-humoral changes resulting in hypothermic effects of centrally applicated BOM.

Animals↗
PubMed1987

Dissociation between apparent volumes of distribution for inulin and sodium by salt adaptation in ducks.

In domestic ducks acclimated to 2% saltwater (SW ducks), chronic elevations of plasma osmolality and sodium concentration, and of the circulating levels of antidiuretic hormone and angiotensin II indicate a trend towards dehydration when compared to ducks maintained on freshwater (FW ducks). Under steady state conditions of salt and water balance, with prevailing antidiuresis and no salt gland secretion, the apparent volumes of distribution of 22Na and of radiolabeled inulin were calculated after single injections of the tracers. The sodium spaces as percent body mass of FW ducks (33.3 +/- 0.9) and SW ducks (31.5 +/- 0.5) were not different, but apparent volumes for inulin distribution differed significantly between FW ducks (31.2 +/- 0.7) and SW ducks (24.8 +/- 0.7). Plasma volumes and rates of inulin disappearance from the plasma during both the non-uniform and uniform phases of tracer distribution were closely similar in FW and SW ducks and support the hypothesis that the difference between apparent volumes of inulin distribution reflects a difference in extracellular fluid volume which was estimated as 20.9% in FW ducks and 17.2% in SW ducks. For SW ducks the difference between inulin and sodium spaces was significantly greater than for FW ducks. In relation to the extracellular fluid compartment SW ducks have a larger pool of non-extracellular exchangeable sodium.

Acclimatization↗
PubMed1987

Effect of acclimation temperature on the elongation step of protein synthesis in different organs of rainbow trout.

Cytosolic extracts of liver, kidney, spleen, gill, red and white muscle from rainbow trout acclimated to 4 and 17 degrees C, respectively, have been investigated in vitro with respect to their enzymic activity in stimulating the growth of nascent peptide chains (labelled polyphenylalanine) at assay temperatures from 5 to 25 degrees C using polyuracil as messenger RNA. The elongation step of protein synthesis is characterized by a Q10 value of about 2.4 (range 10-25 degrees C) in all organs from both, 4 and 17 degrees C acclimated fish. Except for the red muscle, the organs of cold acclimated trout, however, exhibit significantly higher specific elongation rates (mol phenylalanine polymerized/(g wet weight X h)) at any experimental temperature than those of warm acclimated fish. This increase of the elongation rates varies between the organs and ranges from +29% (liver) to +60% in the gill. The specific acylation rate (mol phenylalanyl-tRNA formed/(g wet weight X h] surpasses the specific elongation rate by a factor of at least 8.5. Moreover, the specific acylation rate per mg protein is independent of acclimation temperature. It is concluded that the increased specific elongation rates in 4 degrees C acclimated trout are not due to altered pool sizes of the precursor phenylalanyl-tRNA, but reflect an effective enhancement of enzymic elongation factor activities. In accordance with data taken from literature, this finding suggests a compensatory enhancement of in vivo protein synthesis to occur in trout during cold acclimation.

Acclimatization↗
PubMed1987

Specific UV-absorbancy of pure rRNA isolated from trout liver as a standard for the quantification of ribonucleic acid from fish tissues.

1. Lyophilized crude rRNA from trout (Salmo gairdneri R.) liver was composed (w/w) of 2.9% protein, traces of DNA and glycogen, 13% water and 83% pure rRNA. The RNA content was derived from the discrepancy between effectively found (8.1%, w/w) and theoretical phosphorus content (9.6%, w/w). 2. The theoretical phosphorus content was calculated on the basis of the molar distribution of nucleotides in rRNA (UMP:GMP:AMP:CMP = 24.7%:30%:19.5%:25.8%), established upon cation exchange chromatography of alkali-degraded crude rRNA. 3. The extinction coefficient (corrected for moisture and none-ribonucleic acid contaminants) of pure rRNA in 0.2 N PCA after digestion in 0.3 N KOH at 37 degrees C for 90 min is 361 in terms of E1%260. That of undegraded, pure rRNA in water amounts to 279.

Animals↗
PubMed1987

Interaction of changes in the third ventricular CSF tonicity, central and systemic AVP concentrations and water intake.

Arginine vasopressin (AVP) is assumed to be involved as a central transmitter or modulator in the control of autonomic functions including thirst. In conscious dogs AVP concentration in cerebrospinal fluid (CSF) from the anterior part of the third ventricle (A3V) was analysed before and after local elevation of CSF osmolality by intracerebroventricular (i.c.v.) infusion of 0.35 M NaCl and after i.c.v. AVP infusion at 46 and 138 fmol ml-1 for 10 min. In addition, the effects of these i.c.v. infusions on water intake, plasma AVP concentration and blood pressure were investigated. In euhydrated dogs 0.35 M NaCl i.c.v. did not alter AVP concentration in the CSF during the subsequent 2 h. In contrast, plasma AVP concentration had increased significantly from 3.4 +/- 0.3 (control) to 6.4 +/- 0.7 and 4.7 +/- 0.3 fmol ml-1, 4 and 16 min, respectively, after the hypertonic stimulus. Drinking was stimulated with an average water intake of 14.5 +/- 3.7 ml kg-1 body wt. However, AVP infusion into the A3V did not elicit water intake despite increases of AVP concentration in the A3V by factors up to 40 above control. The same animals responded with spontaneous drinking to 0.35 M NaCl i.c.v. administered 160 min after the end of AVP infusions. Exogenously administered AVP disappeared from the A3V with a time constant of 13.8 min. The results do not support the view that AVP in the A3V CSF per se stimulates drinking.

Animals↗
PubMed1987

Appropriate and inappropriate hypothalamic cold thermosensitivity in Willow ptarmigan.

Hypothalamic thermosensitivity has been investigated in conscious Willow Ptarmigan (Lagopus lagopus lagopus) provided with chronically implanted hypothalamic perfusion thermodes. The birds were exposed to either cold (Ta - 10 degrees C) or warm (Ta + 25 degrees C) ambient conditions while hypothalamic temperature (Thy) was clamped for periods of 20 min at different set levels between 28 degrees C and 43 degrees C. The responses of the animals to hypothalamic thermal stimulation were classified by comparing them with those normally found in mammals. At Ta - 10 degrees C hypothalamic heating inhibited ongoing shivering, causing a fall in body-core temperature (Tc) (appropriate mammalian-like response). Strong levels of hypothalamic cooling (Thy less than 34.0 degrees C) also caused a fall in Tc due to inhibition of shivering (inappropriate mammalian-like response). However, weaker levels of hypothalamic cooling (Thy 34-36 degrees C), facilitated ongoing shivering, resulting in small increases in Tc (appropriate mammalian-like response). At Ta + 25 degrees C hypothalamic heating facilitated ongoing panting while weak (Thy 38 degrees C) levels of hypothalamic cooling inhibited ongoing panting (both mammalian-like responses). The observation of a weak mammalian-like cold hypothalamic thermosensitivity in Willow Ptarmigan indicates that these birds possess some specific cold thermosensors in the hypothalamic region. This finding suggests that hypothalamic temperature dependence in birds and mammals is fundamentally similar.

Animals↗
PubMed1987

Effect of capsaicin upon afferent and efferent mechanisms of nociception and temperature regulation in birds.

(1) Acute capsaicin effects on nociception in the conscious chicken were tested by close arterial injection. The threshold dose to elicit nocifensive and autonomic responses was 50 micrograms, i.e., two to three orders of magnitude higher than in mammals but four times lower than in pigeons. (2) Foot withdrawal from hot water remained unchanged after capsaicin was injected either intravenously in the chicken at a cumulative dose of 600 mg/kg or perineurally at a dose of 100 micrograms into the sciatic nerve of pigeons. (3) Temperature regulation and body temperature in the chicken were not affected by subcutaneous injection of capsaicin, but intravenous infusion at rates of 2-5 or 10-13 mg X min-1 X kg-1 transiently lowered body temperature by 1.5 degrees C and stimulated panting and sometimes vasodilatation of the comb. Repeated capsaicin infusion produced temporary tachyphylaxia but no permanent desensitization. (4) A cumulative dose of 1 g/kg body weight capsaicin reduced the relationship between breathing frequency and respiratory evaporative heat loss in the duck. This deficit was compensated by more pronounced panting and, thus, did not indicate any impairment of temperature regulation. (5) Injection of capsaicin into the sciatic nerve depleted substance P in the dorsal horn of rats. Similar treatment in pigeons caused an increase of substance P immunoreactivity in the dorsal horn. (6) The effects of high capsaicin doses in birds indicate only low susceptibility of afferent neural mechanisms. Some of the effects may be due to a capsaicin action upon efferent neural mechanisms.

Afferent Pathways↗
PubMed1987

Dehydration and arginine vasotocin and angiotensin II in CSF and plasma of pekin ducks.

Osmolalities and, by radioimmunoassay, the contents of arginine vasotocin (AVT) and angiotensin II (ANG II) in simultaneously collected cisternal cerebrospinal fluid (CSF) and plasma samples were determined in chronically prepared conscious Pekin ducks (Anas platyrhynchos) adapted to either freshwater (FW ducks) or salt water (2% saline, SW ducks) for drinking. In FW ducks the AVT in CSF was approximately 10-fold higher than in plasma; ANG II concentration in CSF was about two-thirds of that in plasma. In SW ducks concentrations of AVT were increased approximately threefold and of ANG II fourfold in both CSF and plasma. Dehydration in FW ducks (24-48 h) increased AVT and ANG II in both CSF and plasma, the relative rise being greater in plasma. Within 150 min after rehydration plasma AVT fell at unchanged CSF AVT, whereas CSF ANG II fell at unchanged plasma ANG II. Hydration of SW ducks with freshwater had similar effects. The results indicate separate avenues of release of central and systemic AVT and ANG II and support the idea of an independent control of central ANG II as a mediator in osmoregulation, with CSF AVT reflecting the state of osmoregulatory activity of the hypothalamopituitary vasotocinergic system.

Adaptation, Physiological↗
PubMed1987

[Internal iliac arteriovenous fistulas following gynecologic surgery. Development of principles of treatment. Apropos of 2 cases].

Pelvic arterio-venous fistulae are rare. They can be congenital or acquired. If the latter they are nearly always iatrogenic following surgery for prolapsed intervertebral discs or following gynaecological or obstetrical surgery. Diagnosis is difficult because the symptoms and signs are not specific ore are deceptive. Clinical examination shows that this "tumour" is vascular in nature. Up till recently treatment was disappointing, consisting as it did of surgery which was often difficult and dangerous and possibly carrying a poor prognosis, and in most cases resulting in recurrences. Since intra-arterial embolisation techniques have been developed, either by themselves or before surgery, the results have been better. They cannot be carried out without a preliminary precise and complete arteriographic assessment.

Abortion, Induced↗
PubMed1987

[Microsurgical treatment of lesions of the proximal segment of the oviduct. Isthmo-ostial reimplantation. Isthmo-ostial anastomosis and isthmo-uterine reimplantation].

The authors, who operated on 187 patients with 277 interstitial sections of the isthmus, describe their microsurgical techniques for isthmo-ostial anastomosis, for isthmo-ostial reimplantation and for isthmo-uterine reimplantation. Histological analysis of the lesions and the anatomical features of the proximal segment of the tube justify their method. Patency is re-established and the results are encouraging. All the same, these partial proximal lesions can be markedly improved with success by medical treatment before operation.

Fallopian Tube Diseases↗
PubMed1986

Capsaicin fails to produce disturbances of autonomic heat and cold defence in an avian species (Anas platyrhynchos).

Capsaicin was intravenously administered to adult domestic ducks of 1.8-2.6 kg body weight, with a cumulative dose of 1.0 g/kg body weight given in 4-6 single infusions at intervals of 2-3 days. There were no acute, nociceptive or hypothermic effects, as typically seen in mammals. Before and after capsaicin treatment respiratory evaporative heat loss (REHL, w X kg-1), breathing frequency (BF, min-1) and metabolic heat production (M, w X kg-1) were determined in a warm environment (35-38 degrees C) as a function of core temperature, measured in the esophagus (Tes), which was altered by graded heat extraction with a colonic thermode. Capsaicin treatment reduced the rate at which REHL increased with increasing BF, however, this was compensated by a steeper increase of BF with rising Tes so that the relationship between Tes and REHL remained unchanged. The Tes threshold for activation of M was increased by 0.3 degrees C and the slope reduced by 27% after capsaicin, but identical maximum M values were attained before and after capsaicin at identical degrees of hypothermia. Skin temperature measurements revealed no influence of capsaicin on the threshold Tes values for skin vasoconstriction. It is concluded that capsaicin fails to exert effects in birds on those afferents and central neurons which are involved in thermo- and nociception, in contrast to mammals in which these perceptive functions become severely impaired.

Animals↗
PubMed1986

Thermally induced changes in neural and hormonal control of osmoregulation in a bird with salt glands (Anas platyrhynchos).

In conscious Pekin ducks adapted to hypertonic saline (1.9%) as drinking water, steady state secretion of the salt glands was established by continuous intravenous salt loading and the effects of hypothalamic thermal stimulation on salt gland activity and on the plasma concentrations of arginine vasotocin (AVT) and angiotensin II (AII) were observed. Hypothalamic cooling depressed salt gland secretion and the plasma level of AVT. Hypothalamic warming caused transient activation and subsequent inhibition of salt gland secretion without consistent changes of the plasma levels of AVT and AII. Whole body cooling by heat extraction with a colonic thermode produced moderate inhibition of salt gland activity, without changes in plasma AVT and AII, which may be explained by peripheral vasoconstriction. The results are consistent with the view that hypothalamic osmoregulation is under an influence of local temperature by combined osmo/thermo-responsiveness of hypothalamic neurons and temperature dependence of signal transmission in hypothalamic neural integration of osmoregulation.

Angiotensin II↗
PubMed1986

Complement-dependent lysis of Erhlich ascites tumor cells by human serum (ascitolysin) is lowered in cancer patients and raised in pregnant women.

Normal human serum has been shown to contain IgM antibodies that are lytic to Ehrlich ascites tumor cells in the presence of complement. We call this activity ascitolysin (AL). Using a 51Cr release assay, the AL titers of 164 normal sera, 211 sera from patients with non-malignant disease, 62 sera from 25 pregnant women and 170 sera from cancer patients were estimated. The patient sera were taken preoperatively, and were assigned to the cancer or non-cancer group after histological diagnosis. In normals, higher titers were found in sera of A and O blood groups but not B and AB. The difference was due to a fraction absorbed by B red blood cells. Sera from untreated cancer patients showed significantly reduced titers when compared to normal, benign tumor, chronic and other non-malignant disease groups. In pregnancy, titers were positively correlated with duration and remained elevated for at least 6 weeks post partum. About 30% of AL activity was absorbed by the free galactose groups of agarose. This fraction was significantly lower in untreated cancer patients. Anti-T antigen antibodies do not contribute to AL levels. Galactophilic blocking factors were also found; eight times more frequently in cancer sera than in normals. The non-absorbed fraction was also lower in cancer sera. The data suggest that AL antibodies may be directed against human oncofetal antigens.

ABO Blood-Group System↗
PubMed1986

gp140v-fms molecules expressed at the surface of cells transformed by the McDonough strain of feline sarcoma virus are phosphorylated in tyrosine and serine.

Cells transformed by the McDonough strain of feline sarcoma virus express at their surface a v-fms-specific transmembrane glycoprotein designated gp140v-fms. By labeling with 32Pi, gp140v-fms was shown to be phosphorylated 30-fold more in serine residues than were the cytosolic v-fms polypeptides gp180gag-fms and gp120v-fms. By using the phosphotyrosine phosphatase-specific inhibitor sodium orthovanadate, an additional tyrosine phosphorylation was observed in vivo, again involving predominantly gp140v-fms. In vitro studies showed that the v-fms proteins were phosphorylated by protein kinase C in a calcium- and phosphatidylserine-dependent manner.

Animals↗