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Biomedical subjects

G Kummer

Publications and source records attributed to G Kummer.

29 records · Page 2Linked to original sources
PubMed1980

[Problems of early detection of latent pulmonary hypertension--the value of ergometric tests and the correlation between pulmonary circulation and parameters of lung function (author's transl)].

The possibility of early detection of pulmonary hypertension is rather late according to the large capacity of the lung vessels in the condition of rest. Consequently the parameters of the pulmonary circulation were measured in 89 healthy subjects and 261 men suffering from silicosis in rest and bicycle exercise by means of the microcatheter technique and statistically compared with other parameters of lung function. In conclusion it can be said there is a statistical correlation between pressure at rest and during exercise conditions, but this is not available in an individual case. Furthermore the pressure values of persons suffering from silicosis are higher than those of the healthy group at rest and the pressure rise is higher in the ill group during exercise. Statistically there is a slight correlation between the pressure behavior and the FEV1, Rtot, PO2, DCO and of minor importance to VC, RC and FRC.

Blood Pressure↗
PubMed1980

[The influence of hypobaric hypoxia upon the hemodynamics of the pulmonary circulation (author's transl)].

The influence of hypobaric hypoxia at the pulmonary gaseous exchange and the hemodynamics of the pulmonary circulation was tested by 12 healthy subjects at the age from 33 to 47 years. They were submitted to a basis investigation with determination of VC, VE, VO2, VCO2, Hb, PO2A/a, pH, HR, ECG, PVd, PAp, HZV, RL. These investigations were followed by stress examination by means of the bicycle ergometry in four rectangular steps during conditions of normoxia and of hypobaric hypoxia in a low-pressure chambre at 66.5 kPa (500 Torr) each of 6 min duration. During the influence of hypoxia a PO2a-decrease in a sense of partial insufficiency could be already observed at rest during conditions of a decreased alveolar oxygen-partial-pressure. At the same time was found a significant increase of the systolic peripheral and the diastolic pulmonary arterial pressure. At the increasing step by step ergometric exercise during conditions of the hypoxia stress were growing significance evidence of different reactions of the pulmonary and cardiocirculatory parameters occurred.

Adult↗
PubMed1979

Differential and integral corticosteroid feedback effects on ACTH secretion in hypoadrenocorticism.

Recent work suggests the existence of a dual corticosteroid feedback mechanism of stress-induced ACTH secretion in the rat. This possibility led us to study the kinetics of suppression of ACTH levels by corticosteroid administration in patients with nonstress ACTH hypersecretion secondary to hypoadrenocorticism. Cortisol was administered according to different protocols, which were chosen to provide extreme variations of the input signal. By this means, two phases of suppression of ACTH levels could be differentiated. A first decrease occurred without latency whenever, and as long as, plasma cortisol levels were rising. There was a linear regression between the logarithm of the increments in cortisol concentrations and the decrease in ACTH levels per minute (r = 0.951) (differential or rate-sensitive feedback mechanism). Neither the absolute doses of cortisol, nor plasma cortisol concentrations were closely correlated with the degree of suppression of ACTH by this rapid mechanism. A second decrease in ACTH levels began congruent with30 min after corticosteroid administration. In this case there was a significant linear regression between the degree of inhibition of ACTH levels and the cortisol doses (r = 0.997) (integral or dose-sensitive feedback mechanism). The dose-sensitive feedback effects of dexamethasone were less than might have been predicted from its relative anti-inflammatory potency. No rate-sensitive effects were seen with dexamethasone doses of 1.0 or 1.25 mg.

Adrenal Cortex Hormones↗
PubMed1979

Positive rate-sensitive corticosteroid feedback mechanism of ACTH secretion in Cushing's disease.

To define the nature of the disturbance of the corticosteroid feedback mechanism in Cushing's disease, the dynamic aspects of the ACTH response to corticosteroid administration have been studied in patients with Cushing's disease after total adrenalectomy (C.d. post adx.). The results were compared with those obtained in patients with Addison's disease (control group). Different experimental designs for administration of cortisol were chosen to provide extreme variations in the input signal. The response of the system was evaluated by measuring plasma ACTH concentrations (radioimmunoassay) at short time intervals. Infusion of cortisol at constant rate (50 mg/h for 2 h) resulted in a transient, paradoxical rise in ACTH levels with a maximum at 15 min. (315+/-65%, mean+/-SEM). In contrast, in the control group there was an immediate and rapid decrease in ACTH levels with a significant inhibition after 15 min (80+/-6%, mean+/-SEM). Infusion of 50 mg cortisol for 5 and 15 min, respectively, produced an increase in ACTH levels, which was confined to the time when cortisol levels were rising (maximum: 137+/-30% and 139+/-10% at 5 and 15 min, respectively, mean+/-SEM). This increase corresponded in time to the first decrease in ACTH levels in the Addisonian patients. With bolus injections of 25 mg cortisol, ACTH levels remained unchanged during the first 15 min. The time-course in the patients with C.d. post adx. was essentially the same as in the Addisonian patients. From these results it is concluded that in the patients with C.d. post adx. the rapid, rate-sensitive feedback mechanism was converted into a positive one, whereas the delayed, dose-sensitive mechanism was completely undisturbed. The capacity of dexamethasone to activate rate-sensitive feedback elements was markedly diminished. Accordingly, there were only minor positive feedback effects upon ACTH secretion in the patients with C.d. post adx.

Addison Disease↗
PubMed1978

[Effect of bronchial reactivity on the whole-body plethysmographic inhomogeneity parameter REmax/RE0 and its value in the early diagnosis of chronic nonspecific lung diseases].

Examinations performed with the help of the body-plethysmographic inhomogeneity parameter REmax/RE0 prove the close connection between the development of chronic unspecific pulmonary diseases and the appearance of disturbances of the ventilatory distribution. The functional disturbance metioned is further increased by the bronchial provocation and may partly be demonstrated in a characteristic way also in inconspicuous initial findings. The body-plethysmographic inhomogeneity parameter REmax/RE0 is, however, not suited for the early diagnosis of chronic unspecific pulmonary diseases, since with its help the verification of disturbances of the ventilatory distribution is successful only then, when the total resistance is already increased. For the final judgment of the aptitude of the bronchial reactivity test for the increase of the valency of methods of the distribution analysis in the early diagnosis further examinations are necessary.

Adolescent↗
PubMed1978

[Evaluation of measurement accuracy in microcatheterization of the heart].

In 192 patients with silicosis the results of the cardiac micro-catheterisation under conditions of rest were compared with those ones of a secondary examination performed two years later. This allows conclusions to the behaviour of the pressure values measured in the period observed as well as to the evidence of an individual cardiac micro-catheterisation. No essential increase of the mean pressure of the pulmonary artery was observed. The dispersion of an individual measurement is 3 Torr. A pulmonary hypertension, which is given from 20 Torr upwards, consequently may be established with a 95% statistical certainty only from an individual measuring value of 26 Torr.

Blood Pressure↗
PubMedDate not supplied

High-affinity binding of crustacean hyperglycemic hormone (CHH) to hepatopancreatic plasma membranes of the crab Carcinus maenas and the crayfish Orconectes limosus.

The binding properties of the crustacean hyperglycemic hormone (CHH) of two species, the shore crab, Carcinus maenas (Brachyura) and the crayfish, Orconectes limosus (Astacura), were investigated using purified plasma membranes of one of the main target organs, the hepatopancreas. Assays were performed under equilibrium binding conditions with 125I-CHH as labeled ligand and unlabeled CHH in increasing concentrations as displacing ligand. In both cases, comparable binding characteristics were observed for the homologous CHH to the respective hepatopancreatic membrane source, indicating saturable and displaceable binding with nonlinear dependence on monovalent cations and a dissociation constant (Kd) of 4 to 6 x 10(-10) M. Binding capacity was in the range of 200-400 fmol/mg membrane protein. In heterologous displacement studies a certain degree of species specificity was found, particularly with regard to selective binding by the Orconectes receptor, suggesting that the group specificity of biological activity of CHH reflects coevolution of both hormone and receptor.

Animals↗