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Biomedical subjects

U Hübner

Publications and source records attributed to U Hübner.

At least 37 records · Page 2Linked to original sources
PubMed1997

A multicentre evaluation of the CA 15-3 assay, CA 19-9 assay and CA 125 II assay on the Bayer Immuno 1 System.

The analytical performance of the tumour markers CA 15-3 assay, CA 19-9 assay and Ca 125 II assay on the Bayer Immuno I System was studied according to a revised version of the ECCLS guidelines (Haeckel R. In: Evaluation methods in laboratory medicine, Weinheim, VCH Verlag 1993:47-69) in a multicentre evaluation involving five laboratories. Determination of the 3 analytes generated more than 6000 data. On the Bayer Immuno I System, the imprecisions of the CA 15-3 assay, CA 19-9 assay and CA 125 II assay were better than those found for comparison methods. The median recovery over all five laboratories of system assigned values in control sera was within the 1-s range for the three tumour marker assays. No deviation of linearity could be detected experimentally for all assays. Results for patients' samples showed acceptable agreement between the Bayer Immuno 1 system and several different comparison methods in most cases. One exception was the CA 15-3 assay in comparison with the MCA assay from Roche Diagnostic Systems, where the large difference in values is due to the use of different antibodies and calibrators in the two assays. No carry-over effects could be detected. The selective Bayer Immuno 1 system is fully automated; its practicability was rated as high.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1996

Slow rhythmic oscillations of blood pressure, intracranial pressure, microcirculation, and cerebral oxygenation. Dynamic interrelation and time course in humans.

BACKGROUND AND PURPOSE: Various biological signals show nonpulsatile, slow rhythmic oscillations. These include arterial blood pressure (aBP), blood flow velocity in cerebral arteries, intracranial pressure (ICP), cerebral microflow, and cerebral tissue PO2. Generation and interrelations between these rhythmic fluctuations remained unclear. The aim of this study was to analyze whether stable dynamic interrelations in the low-frequency range exist between these different variables, and if they do, to analyze their exact time delay. METHODS: In a clinical study, 16 comatose patients with either higher-grade subarachnoid hemorrhage or severe traumatic brain injury were examined. A multimodal digital data acquisition system was used to simultaneously monitor aBP, flow velocity in the middle cerebral artery (FVMCA), ICP, cerebral microflow, and oxygen saturation in the jugular bulb (SjO2). Cross-correlation as a means to analyze time delay and correlation between two periodic signals was applied to a time series of 30 minutes' duration divided into four segments of 2048 data points (approximately 436 seconds) each. This resulted in four cross-correlations for each 30-minute time series. If the four cross-correlations were consistent and reproducible, averaging of the original cross-correlations was performed, resulting in a representative time delay and correlation for the complete 30-minute interval. RESULTS: Reproducible cross-correlations and stable dynamic interrelations were found between aBP, FVMCA, ICP, and SjO2. The mean time delay between aBP and ICP was 6.89 +/- 1.90 seconds, with a negative correlation in 81%. A mean time delay of 1.50 +/- 1.29 seconds (median, 0.85 seconds) was found between FVMCA and ICP, with a positive correlation in 94%. The mean delay between ICP and SjO2 was 9.47 +/- 2.21 seconds, with a positive correlation in 77%. Mean values of aBP and ICP did not influence the time delay and dynamic interrelation between the different parameters. CONCLUSIONS: These results strongly support Rosner's theory that ICP B-waves are the autoregulatory response of spontaneous fluctuations of cerebral perfusion pressure. There is casuistic evidence that failure of autoregulation significantly modifies time delay and the correlation between aBP and ICP.

Blood Pressure↗
PubMed1995

Long-term follow-up of children with diaphragmatic hernia.

From 1962 to 1988, 147 neonates were admitted for operative repair of CDH to the Division of Pediatric Surgery in the Children's Hospital of Cologne. Follow-up studies were performed on 45 patients ages 1 to 25 years representing 54.2% of the 83 survivors. 18 patients (40%) were entirely without any complaints, 11 patients (24.4%) had increased rates of respiratory infections. Especially in early childhood they suffered from obstructive alterations in the respiratory tract. No restrictive pulmonary changes were observed. Scintigraphic ventilation tests were performed on 44 cases. 34 (77%) tests indicated absolutely normal results. Some rare local deficits of lung ventilation were based on adhesive anatomic alterations of the thoracic skeleton and the diaphragm. The lung function tests conducted in 29 persons ages 6 to 25 years revealed that the vital capacity and the forced expiratory volume were all normal. We found an increase of the intrathoracic gas volume in 11 infants (disposition to pulmonary inflation). In 9 cases we observed a decrease in the mid expiratory flow curves and in 6 patients we measured an increase in the specific resistance of airways (tendency towards obstructive airway alterations). Nevertheless even former hypoplastic lungs revealed a good extensibility.

Adolescent↗
PubMed1994

Transient behaviour of baker's yeast during enforced periodical variation of dissolved oxygen concentration.

The aim of the investigation was to find out the influence of the variation of the dissolved oxygen concentration in the microenvironment of yeast cells on their physiological behaviour in small laboratory reactors and estimate their behaviour in large industrial reactors. Since the morphology of the laboratory and industrial yeasts differed considerably, their transient behaviour was investigated and compared. For this purpose, the strain Saccharomyces cerevisiae H620 and an industrial strain were cultivated on synthetic as well as on complex medium in batch operation during periodical variation of the dissolved oxygen concentration, monitoring the most important key parameters. Also the yeast was cultivated in batch as well as in continuous operation, the cell-containing culture medium was recirculated through a nonaerated loop at different recirculation rates (residence times of the cells in the loop), and the key operation variables were monitored. It was found that the transient behaviour of laboratory and industrial yeasts differed slightly. Since cells growing in batch culture are more sensitive to dissolved oxygen concentration variation than cells growing in continuous culture, the transient behavior of cells cultivated in batch operation varied from those in continuous operation. If the anaerobic phase was longer than 1 min, ethanol was produced. However, it was consumed during the aerobiosis again, provided that phase was considerably longer than the anaerobic phase. This means that the yeast cultivation was not influenced by the periodic operation of the dissolved oxygen. Judging from the measurements in large stirred tank and airlift tower loop reactors, in general, the cells would spend more time in the aerobic than in the anaerobic flow region, and they would spend less than 1 min in the anaerobic flow region. Therefore, no considerable effect of the periodically varied dissolved oxygen concentration on the cell cultivation can be expected in large-scale reactors. In the stirred tank-loop-system at high pumping rates/high frequencies of periodically varied dissolved oxygen concentration, unexpectedly, the formation of ethanol was observed, which might be caused by stress imposed on the cells.

Biotechnology↗
PubMed1993

[The value of scintigraphic functional assessment in extreme hydronephrosis].

Renographic studies are occasionally suspected of overestimating the excretory function of obstructed kidneys. Presenting the case of a ten months old boy with obstruction of the ureterovesical junction and severe hydronephrosis, we discuss the validity of the assessment of renal function by radionuclide urography. Normal postoperative excretion as well as renographic controls confirmed the good relative function of the hydronephrotic kidney. Instead of nephrectomy a reconstructive operative procedure was employed.

Humans↗
PubMed1990

Activation signals in human lymphocytes: interleukin 2 synthesis and expression of high affinity interleukin 2 receptors require differential signalling for the activation of protein kinase C.

The mitogenic activation of resting T lymphocytes involves two distinct cellular events, the synthesis of the ultimate mitogen interleukin 2 and the synthesis and expression of receptors for it. In order to get more detailed information on the mechanisms associated with these activating steps (the effects of different stimuli, leading to activation of protein kinase C were investigated in human lymphocytes). The anti-T-cell receptor (TCR) and anti-CD3 monoclonal antibodies (BMA 031 and BMA 030, respectively), as well as the combination of the phorbol ester, TPA, with a calcium ionophore-induced interleukin 2 synthesis and subsequent proliferation in human peripheral blood lymphocytes. Incubation of cells with synthetic diacylglycerols and calcium ionophores proved to be effective in expression of high affinity interleukin receptors, no detectable amounts of interleukin 2 were, however, synthetized. When diacylglycerols were, however, added repetitively, interleukin 2 was also produced. Both anti-TCR/CD3 antibodies and TPA or DiC8 caused activation and translocation of protein kinase C from the cytosol to the plasma membrane. Significant differences, however, were observed between the time kinetics of the translocation of the enzyme. In plasma membranes of TPA-stimulated cells activation of protein kinase C was detectable up to 4 hr. In contrast, the highest specific activity of protein kinase C was measured in the plasma membranes after 15 min of DiC8 addition to cells. Anti-CD3 monoclonal antibodies activated protein kinase C in a biphasic manner. Shortly after binding of BMA 030 to the T cell antigen receptor/CD3 complex the activity of protein kinase C was increased in the plasma membrane, then it declined to control levels followed by a second long-lasting activation of the enzyme up to 4 hr. These results suggest different signal requirements for different activation steps. While for synthesis and expression of interleukin 2 receptors a short term activation of protein kinase C is sufficient, long-term activation of the enzyme is necessary for interleukin 2 synthesis in human lymphocytes.

Biological Transport↗
PubMed1989

Antioxidants for bone marrow cryopreservation.

Addition of antioxidants into the preservation solution improved the cryoprotection of human bone marrow cells. The viability was studied by the growth of GM-CFC in agar culture before and after storage at -196 degrees C. All used antioxidative drugs (selenomethionine, methionine, tocopherol, penicillin/Fe++) increased the tolerance of the stem cells to freezing and thawing and elevated the number of surviving GM-CFC up to the twofold in comparison with that of controls. More immature colony forming cells were especially protected.

Antioxidants↗
PubMed1987

Antioxidants increase the cryoresistance of GM-CFC.

The influence of antioxidative drugs on the cryopreservation of human bone marrow cells was studied. The viability of bone marrow cells was tested after freezing and thawing from--196 degrees C by the growth of GM-CFC in agar culture. The results suggest the ability of antioxidants to protect stem cells against damage caused by freezing and thawing. Addition of tocopherol or penicillin to a cryoprotective medium increases the number of surviving GM-CFC. From the colony-to-cluster ratio can be concluded that antioxidants especially protect more immature haematopoietic (colony forming) cells.

Antioxidants↗