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Biomedical subjects

D Krebs

Publications and source records attributed to D Krebs.

At least 271 records · Page 15Linked to original sources
PubMedDate not supplied

[Lung maturation during artificial placentation and mechanical lung distension].

An new method of lung maturation during artificial placentation was evaluated during a series of 15 animal experiments in premature lambs (gestational age 125-132 days). Perfusion circuit with interposition of a membrane lung was connected with the umbilical vessels. Extracorporeal CO2-removal (ECCO2-R) and apneic oxygenation were provided during lung distension. The ultramicroscopic pattern approved a maturation of the lung during the procedure showing development of lamellar bodies and surfactant secretion into the alveolar space. The biochemical analysis of the tracheal fluid showed a significant increase of both PC and PG concentrations (3.225 +/- 1.112 mg/100g to 24.228 +/- 3.36 mg/100 g respectively 0.249 +/- 0.11 mg/100 g of 0.622 +/- 0.09 mg/100 g. The biophysical function of the lung was also improved as was shown by a significant increase of the statistical compliance. We conclude that artificial placentation and lung distension might be a new mode of prophylaxis for respiratory distress syndrome in critically immature babies.

Animals↗
PubMedDate not supplied

[Intracranial hemodynamics in phenobarbital administration].

The effect of phenobarbital application on cerebral hemodynamics was studied in premature lambs. Near infrared spectroscopy was used for noninvasive monitoring of oxyhemoglobin, deoxyhemoglobin, total hemoglobin and cytochrom a/a3. Total intracranial blood volume decreased shortly after giving the drug and remained then on a stable lowered niveau. This could be explained with shifting of blood in different brain regions or with a decreased total intracranial blood volume.

Animals↗
PubMedDate not supplied

[The influence of umbilical cord compression on the fetal brain--an animal experiment using laser spectroscopy].

In order to evaluate the influence on the fetal brain due to compression of the umbilical cord biochemical and biophysical changes were traced during defined occlusions of 60 sec by means of NIR laser spectroscopy. Synchronously blood samples were drawn intermittently from a catheter positioned in the A. carotis and analysed for blood gases. The saturation values measured in the fetal blood correlated significantly with the dates of the HbO2 tracing of the NIR-system (r = 0.81, p less than 0.001). After induced occlusion of the umbilical cord a reproducible pattern of the NIR tracing occurred. While an immediate fall in HbO2 occurred, a synchronous rise in desaturated Hb was observed. For the changes of the cytochrome aa3 we detected a minor decrease that occurred with a lag time. Additionally there was an indication of a major change of blood volume as the total Hb content augmented during each compression. We concluded: Changes of Hb-saturation in the fetal blood are immediately indicated by NIR-laser spectroscopy. During cord occlusion of 60 sec. the intracellular oxygenation decrease only after a significant lag time and are reversible and furthermore it leads to a reproducible change of intracerebral blood volume.

Animals↗
PubMedDate not supplied

Determination of TNF alpha, interferon alpha, interleukin 2 and reactivity in the leucocyte migration inhibition test in breast cancer patients.

To date, the results concerning the prognostic importance of parameters of cell-mediated immunity in breast cancer patients are very contradictory; moreover, in most of them the results are hardly comparable due to methodological differences and heterogeneous groups of patients. In 123 patients with nonmetastatic breast carcinoma TNF alpha, INF alpha, IL 2 and reactivity in the leucocyte migration inhibition test (LMI-Test) against autologous tumor tissue were determined and the results correlated with the clinical course of the disease up to a maximum of 108 months. In breast cancer patients TNF alpha-serum levels were significantly (p less than 0.05) elevated compared to healthy controls. We also found that patients with progressive disease had higher levels than patients without recurrences. There were no differences concerning the IL-2 and IFN alpha serum levels between cancer patients and controls, nor did we find a correlation with the clinical course of the disease. In 38% of all breast cancer patients examined, a MIF production against tumor tissue could be demonstrated in the LMI-test. There was no difference concerning the LMI-reactivity between the groups of lymph-node negative and positive patients, but the observation that those patients with an unfavourable clinical course respond more frequently with an enhanced macrophage migration and rarely with migration inhibition was considered of notable prognostic significance. According to these results, it is possible that determination of TNF alpha and delayed type hypersensitivity reaction against tumor tissue in the LMI-test is of clinical value for the determination of risk groups.

Biomarkers, Tumor↗
PubMedDate not supplied

[Hemodynamic adaptation during extracorporeal perfusion and arteriovenous extracorporeal CO2 removal].

During an animal study using five bastard dogs the hemodynamic relations during extracorporeal perfusion with an arteriovenous circuit and extracorporeal CO2 removal (ECCO2-R) were analyzed. We utilised a prototype circuit (Promed, West-Germany) which is by diminution and using silicon rubber adapted to the application in newborn. A silicon lung (Scimed, 0.8 m2, ECCO2-R) was used in the circuit. During the six hours perfusion period a main arterial blood pressure of 83 +/- 17 mmHg and an extracorporeal blood flow of 412 +/- 56 ml/min was found using arteriovenous perfusion via the femoral artery and vein. We found a statistical significant correlation (r = 0.66) between the main arterial blood pressure and the extracorporeal blood flow. Further more there was a significant correlation between the arterial PCO2 and the blood flow through membrane lung (r = 0.81). In conclusion our animal experiments approved the possibility of hemodynamic adaptation to an arteriovenous circuit as well as effectiveness of CO2 removal via such circuit.

Animals↗
PubMedDate not supplied

[Endocrine parameters during artificial placentation and postnatal lung maturation].

During a experimental study in premature lamb the adaptation to a artificial placenta was evaluated by means of analysis of endocrine parameters. Performing cesarean section on day 125.-135.13 premature lambs were born and connected to a extracorporeal circuit providing CO2-Removal (ECCO2-R) during apnoic oxygenation over a period of 3 hours and 17 minutes mean duration. The intermittent analysis of 6 endocrine parameters was performed at the beginning of the experiment, after 1 hour and after 3 hours. TSH showed an statistical significant increase from a initial concentration of 0.638 +/- 0.051 microE/ml to 0.992 +/- 0.093 microE/ml after 1 hour (p 0.01). For T3 we found 0.273 +/- 0.074 nmol/l and 0.809 +/- 0.124 nmol/l. For RT3 we detected a decrease as the initial value was 4.304 +/- 0.474 ng/ml whereas after one hour we found 2.040 +/- 0.153 ng/ml. ACTH values increased from 543 +/- 109 pg/ml to 1150 +/- 194 pg/ml after 1 hour. Cortisol values increase from 39.6 +/- 7.5 ng/ml to 55.3 +/- 11.9 ng/ml. No significant change was found during the analysis of beta-endorphin concentrations. We conclude that the adaptation to artificial umbilical circulation is possible. Furthermore detected changes of endocrine parameters, namely cortisol and thyroxin levels, should provide a basis for postnatal organ maturation.

Adaptation, Physiological↗
PubMedDate not supplied

[Laser spectroscopy in the newborn infant--initial experiences].

Equipment for near-infrared laserspectroscopy for clinical application is newly available. By this technique noninvasive monitoring of biochemical parameters is achievable. We report on our first experience with a Radiometer prototype for such NIR laserspectroscopy during measurements in 5 neonates. Laserdiodes provide emission at a wavelength of 775, 805, 845 and 904 nm. The registered signals are computerized aiming at a calculation of relative changes of saturated and unsaturated hemoglobine, changes in blood volume and cytochrome aa-3. In this article graphical display of the parameters give insights in the redoxstate and the hemodynamics of the biological sample. The near-infrared laserspectroscopy has the potential of becoming an instrument for the study of biophysical and biochemical alterations in the newborn.

Brain Damage, Chronic↗
PubMedDate not supplied

In vitro activity of titanocenedichloride versus cisplatin and doxorubicin in primary and recurrent epithelial ovarian cancer.

BACKGROUND: Titanocenedichloride (MKT 4) is a new antineoplastic metal complex with proven activity in several experimental tumors. MATERIAL AND METHODS: In the present study, the cytotoxic activity of titanocenedichloride in fourteen primary and twelve recurrent ovarian carcinomas (OvCA) was evaluated by an in vitro adenosine triphosphate (ATP) bioluminescence assay. RESULTS: In primary tumors, MKT 4 was found to be at least as effective as cisplatin (DDP) and doxorubicin (DOX). In samples derived from pretreated patients, titanocenedichloride was even more active. In both groups of tumors, a lack of cross resistance between the two metal compounds as well as between MKT 4 and DOX was apparent. The new agent was found to be active in eight of seventeen DDP-resistant (primaries: n = 4; recurrences n = 4) and also eight of seventeen DOX-resistant tumors (primaries: n = 4; recurrences n = 4). CONCLUSIONS: These results indicate a remarkable in vitro activity of titanocenedichloride in native OvCA specimens, even in those exhibiting resistance against cisplatin or doxorubicin. The putative role of this novel drug for the future therapy of OvCA should be evaluated by additional in vitro and in vivo studies.

Adenosine Triphosphate↗