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  • 1
    ISSN: 1432-1440
    Keywords: Thyrotropin-releasing hormone ; RIA-TRH ; Pharmacokinetics ; Hypothyroidism ; Hyperthyroidism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The pharmacokinetics of thyrotropin-releasing hormone (TRH) were assessed following an i.v. injection in blood of ten hyperthyroid, ten hypothyroid, and six normal subjects. A single-compartment model was employed. After methanol extraction, TRH concentrations were analyzed using a specific radioimmunoassay technique combined with fast protein liquid chromatography (FPLC). As for the basal levels of TRH, no differences were observed in either study group. Peak concentrations were always present two min after the injection of TRH. In the euthyroid subjects, TRH blood levels had a half-life (t 1/2) of 6.5±0.41 min, mean±SD, whilet 1/2 was 7.2±0.62 min in the hyperthyroid andt 1/2 was 12±1.67 min (p〈0.001) in the hypothyroid patients. The metabolic clearance rate (MCR) (82.2±15.3 liters/m2/day vs. 89.8±17.2) and the volume of distribution (Vd) (7.1±4.2 liters vs. 7.3±3.4) were approximately the same in the normal subjects and in the hyperthyroid group. MCR (66.2±15.3 Iiters/m2/day) and Vd (6.2±3.3 liters) were found to be lower in the hypothyroid patients. In FPLC, when TRH was added to plasma, it eluted in one peak. Blood samples taken 5 min after TRH i.v. injection had an elution profile of 9.94 ml. These data indicate that 1) TRH has a very short half-life, 2) hypothyroidism can prolong thet 1/2 of exogenous TRH, and 3) when TRH should be used in clinical studies, the function of the thyroid gland has to be taken into consideration.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Secretin ; pancreozymin ; exocrine pancreatic insufficiency ; insulin ; free fatty acids ; glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé L'effet des hormones intestinales sécrétine et pancréozymine sur la sécrétion d'insuline, sur la glycémie, les acides gras et le glycérol a été étudié chez onze malades sans diabète mais ayant une insuffisance pancréatique exocrine d'après des résultats cliniques et chimiques. Un groupe de 30 sujets normaux a été utilisé comme témoins. Les hormones intestinales n'ont causé aucune augmentation d'insuline dans le sérum des malades ayant une insuffisance pancréatique exocrine. La sécrétion d'insuline après l'injection intraveineuse de glucose était normale. Il semble que la présence du tissu exocrine du pancréas soit nécessaire pour obtenir une stimulation de la sécrétion d'insuline par la sécrétine et la pancréozymine. Comme il était prévu, il n'y a pas eu chez ces malades — contrairement à ce qui se passe chez les personnes normales — de sécrétion d'insuline différente après l'application de glucose oral et intraveineux. Ces résultats montrent que la similitude des modifications de l'insuline plasmatique après administration de glucose par voie orale et parentérale peut signifier un mauvais fonctionnement du pancréas exocrine. On peut en déduire qu'un récepteur du glucose de la cellule bêta ou de la membrane superficielle peut opérer indépendamment du tissu pancréatique exocrine et des hormones intestinales. D'autre part, il est proposé comme conclusion qu'un «entérorécepteur» de la cellule bêta est sensible à l'action des hormones intestinales et qu'il est dépendant, plus ou moins, d'un tissu pancréatique exocrine.
    Abstract: Zusammenfassung Bei 11 nicht-diabetischen Patienten mit klinisch und laborchemisch nachgewiesener chronischer exkretorischen Pankreasinsuffizienz wurde die Wirkung der intestinalen Hormone Sekretin und Pankreozymin auf die Insulinsekretion, den Blutzucker, die freien Fettsäuren und das Glycerin untersucht und verglichen mit den an 30 normalen Versuchspersonen gewonnenen Befunden. — Bei den Patienten mit exkretorischer Pankreasinsuffizienz bewirkten die oben genannten intestinalen Hormone keine Erhöhung des Seruminsulins, obwohl die Insulinsekretion nach der i.v. Verabreichung von Glucose nicht beeinträchtigt war. Offensichtlich ist für eine Insulinausschüttung nach Sekretin und Pankreozymin beim Menschen ein intaktes exkretorisches Pankreas erforderlich. Erwartungsgemäß konnte bei diesen Patienten, im Gegensatz zu Normalpersonen, kein Unterschied in der Insulinausschüttung nach oraler und intravenöser Verabreichung von Glucose festgestellt werden. Aus diesen Ergebnissen ist zu schließen, daß die Ähnlichkeit der Plasmainsulin-Veränderungen nach oraler und parenteraler Gabe von Glucose bereits auf einen frühen Schaden der exokrinen Pankreasfunktion hinweisen könnte. Man kann daraus die Folgerung ziehen, daß ein (hypothetischer) „Glucose receptor“ derβ-Zelle oder ihrer Oberflächenmembran mehr oder weniger unabhängig von exokrinem Pankreasgewebe und intestinalen Hormonen funktioniert. Andererseits scheint der „Entero-Rezeptor“ derβ-Zelle, der auf die insulinstimulierende Wirkung der intestinalen Hormone reagiert, mehr oder weniger abhängig zu sein von ausreichendem Vorhandensein intakten exokrinen Pankreasgewebes.
    Notes: Summary In 11 non-diabetic patients with clinical and laboratory evidence of chronic exocrine pancreatic insufficiency, the effect of intestinal hormones secretin and pancreozymin upon insulin secretion, blood sugar, free fatty acids and glycerol was studied and compared with the findings obtained in 30 normal volunteers. — In the patients suffering from exocrine pancreatic insufficiency the above mentioned enterohormones did not elicit any increase in serum insulin although insulin secretion after i.v. glucose loads was perfectly undisturbed. Obviously, the mediator inducing insulin release following secretin and pancreozymin in man depends on intact exocrine pancreatic tissue. As had been expected, no differences in the serum-insulin responses to oral and intravenous glucose, as found in normals, were established in these patients. From theses results it is inferred that similarity of plasma insulin changes after oral and parenteral glucose loads might hint at an early impairment of exocrine pancreatic tissue function. That implies, that a (hypothetical) “Glucose receptor” of theβ-cell or its surface works more or less independently of both the exocrine pancreatic tissue and the intestinal hormones. On the other hand, the “Entero-receptor” of theβ-cell responding to the insulin-stimulating action of intestinal hormones, such as secretin and pancreozymin, is likely to be more or less dependent upon sufficient amounts of intact exocrine pancreatic tissue.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 67 (1989), S. 530-534 
    ISSN: 1432-1440
    Keywords: Hypothyroidism ; Pulmonary circulation ; Pulmonary vascular resistance ; Hemodynamic evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of acute hypothyroidism on the pulmonary circulation was studied in 9 nonobese athyreotic patients by right heart catheterization at rest and during exercise. The patients were studied while they were hypothyroid 2 weeks after ceasing triiodothyronine treatment and while they were euthyroid on replacement therapy. At rest, pulmonary blood flow [4.0±0.6 l/min vs 5.8±1.0 l/min,p〈0.01] and systolic pulmonary artery pressure [18±3 mmHg vs 23±2 mmHg,p〈0.01] were lower when the patients were hypothyroid than when they were euthyroid. The mean and diastolic pressures in the pulmonary artery and the pulmonary capillary pressures were not different among the groups. Likewise, thyroid hormone levels had no significant effect on pulmonary vascular resistance [100±25 dyn-s-cm−5 vs 90±23 dyn-s-cm−5]. With supine exercise, pulmonary blood flow [10.1±1.6 l/min vs. 13.2±2.0 l/min,p〈0.01], mean pulmonary artery pressure [25±6 mmHg vs 30±6 mmHg,p〈0.02], and systolic pulmonary artery pressure [36±6 mmHg vs 44±8 mmHg,p〈0.01] were lower when the patients were hypothyroid. The diastolic pulmonary artery pressure and the pulmonary capillary pressure were similar in both thyroid states. Again, thyroid deficiency had no effect on pulmonary vascular resistance [81±23 dyn-s-cm−5 vs 76±24 dyn-s-cm−5]. The lower systolic pressures in the pulmonary artery seen in hypothyroidism are probably due to the decreased systolic volume load of the pulmonary circulation. The data do not suggest that thyroid hormones play a role in the regulation of pulmonary vascular resistance.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1433-8580
    Keywords: Secretin ; Cholecystokinin-Pancreozymin ; Intestinal hormones ; Intestinal absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of natural secretin (90%) and synthetic secretin as well as impure (10%) and pure (99%) cholecystokinin-pancreozymin (CCK) on net absorption of water, electrolytes, and glucose in human jejunum were studied in 31 normal subjects. An intestinal perfusion technique with a triple-lumen tube was used. Net absorption of water and solute was significantly inhibited by both hormones only with larger doses, pure CCK being less active than impure CCK. A dose-dependent response of water and electrolyte absorption to graded doses of pure CCK was observed, without concomitant inhibition of glucose absorption with lower doses. The findings suggest that secretin and CCK may not be of physiologic importance regarding intestinal absorption in man. The definite changes in intestinal motility and transit rate caused by these hormones seem more likely to result in a reduction of intestinal absorption and an increase in the secretion of water and electrolytes along the proximal small bowel.
    Type of Medium: Electronic Resource
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