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Biomedical subjects

H Körber

Publications and source records attributed to H Körber.

15 recordsLinked to original sources
PubMed1999

Purification of morphologically and functionally intact human basophils to near homogeneity.

Certain studies on basophils require highly purified functionally intact cell preparations. Here, a three-step procedure is described that meets these requirements. The procedure consists of a Ficoll density gradient step, counterflow elutriation and negative selection by magnetic cell sorting (MACS). The mean purity of basophils obtained from 30 donors was 97.6+/-3.96% with a viability of 99.6+/-0.83%. The recovery rate was 49.7+/-15.6%. The cells had a normal morphological appearance as assessed by May-Grünwald-stained cytospins and were functionally intact as shown by their unaltered capacity to release histamine and interleukin 4 (IL-4) following immunological activation. This procedure is a clear improvement over currently available techniques and should facilitate future investigations on basophils.

Basophils↗
PubMed1998

Extended Electrokinetic Characterization of Flat Solid Surfaces.

An experimental setup has been developed and applied for the combined determination of the electrokinetic potential and the surface conductivity of flat surfaces. The key feature of the new device (designated as microslit electrokinetic setup) is the variability of the distance between two parallel flat sample surfaces (10 mm x 20 mm) forming a slit channel. The setup allows us to decrease this distance down to about 1 µm keeping the surfaces parallel. In consequence, streaming potential measurements can be performed at a given solid/liquid interface both at conditions where surface conductivity is negligible and at conditions where surface conductivity significantly contributes to the total channel conductivity. The zeta potential is calculated at different channel geometries based on streaming potential and channel conductivity data and, alternatively, based on streaming current measurements and the dimensions of the cross section of the slit channel. The results obtained were found to agree well if correct conductivity values for the calculation of the zeta potential based on the streaming potential data are used. The surface conductivity is determined from the extrapolation of the channel conductance values gained at a number of sufficiently small distances between the parallel sample surfaces to the distance zero. An additional feature of the developed microslit electrokinetic setup is the assessability of the hydrodynamic thickness of adsorbed layers of macromolecules or particles at the investigated flat surface. In a series of measurements a plasma-deposited fluoropolymer (PDFP) layer on top of a glass carrier and an adsorption layer of the blood protein fibrinogen on top of the PDFP layer were characterized by zeta potential and surface conductivity measurements in different aqueous electrolyte solutions (KCl, KOH, HCl). For the PDFP/solution interfaces zeta potential up to -100 mV were obtained in solutions of neutral pH exclusively due to preferential ion adsorption. After adsorption of fibrinogen the zeta potential is considerably reduced. For the PDFP/solution interfaces surface conductivities were determined in the range of (1-2) x 10(-9) S. The contribution of the diffuse layer to the surface conductivity has been calculated from the zeta potential according to the approach of Bikerman (Kolloid Z. 72, 100 (1935)) and compared with the experimentally determined surface conductivity. Based on this comparison ions in hydrodynamically immobile interfacial layers were concluded to contribute considerably to the surface conductivity in all investigated cases. This so-called additional surface conductivity is attributed to the accumulation of hydroxide and hydronium ions in the Stern layer. Both the high specific mobility of these ions (as compared to the potassium and the chloride ions) and the conductivity of the charge determining species may contribute to the experimental observations. After adsorption of fibrinogen onto the PDFP surface the additional surface conductivity is increased by about an order of magnitude. The latter fact is assumed to be caused by the presence of mobile ions in the interfacial volume of the adsorbed protein layer. In addition to the electrochemical characterization of the adsorbed protein layer its hydrodynamic thickness has been determined by means of liquid flow measurements with the microslit electrokinetic setup. The obtained value of 48 +/- 5 nm correlates well with the protein dimensions given in the literature and is in the order of magnitude of the optical layer extension determined by ellipsometry. Copyright 1998 Academic Press.

Journal Article↗
PubMed1995

[Percutaneous transhepatic cholangioscopy (PTCS)--an important supplement in diagnosis and therapy of biliary tract diseases (indications, technique and results)].

In 39 patients with biliary disease inappropriate for a transpapillary access (21 m, 18 f, mean age 62 y.) 61 percutaneous transhepatic cholangioscopies (PTCS) were performed. In 28 cases (71.8%) diagnostic PTCS was done in order to investigate the etiology of a biliary stenosis. Nine of these patients had histological as well as clinical outcome indicating a benign lesion. Histology was positive for malignancy in 14 (82%) out of 17 patients with clinically assumed malignant stenosis. The etiology of the stenosis remained obscure from a clinical point of view in two cases with negative histology for malignancy. In twelve patients (30.7%) we performed PTCS for endoscopically controlled laser or electrohydraulic lithotripsy of bile duct stones. The procedure was successful in all patients and stone fragments were delivered to the duodenum by saline lavage. Seven of these patients had stones combined with a benign stenosis and were additionally treated by long-term drainage (Yamakawa drain) for three to twelve months. Two of the seven patients had no relaps of the biliary stricture after a follow-up of ten and twelve months respectively. In five cases (12.8%) PTCS controlled insertion of a guide-wire was attempted after failure of the radiologically guided internalization of the percutaneous drainage. The procedure was successful in three of these patients.

Adult↗
PubMed1992

Estimation of extracellular space and blood volume using bioelectrical impedance measurements.

The bromide-82 dilution space (extracellular space, ECS) and blood volume (BV) were measured in 21 patients with esophageal and gastric cancer and in 27 patients 18-96 months after total gastrectomy. Resistance (R) and reactance (Xc) from bioelectrical impedance measurements were used to obtain multiple regression equations for ECS and BV. The variables weight, gender, and height 2/Xc were independent predictors of ECS (r = 0.767; P less than 0.0001). Height 2/R and gender were predictors of blood volume (r = 0.856; P less than 0.0001). The mean difference between the Br space and the ECS predicted from impedance measurements was 0 +/- 1.54 (mean +/- SD). The limits of agreement (+/- 2 SD) were therefore +/- 3.08 l or 19.6% of the mean Br space of 15.7 l. The limits of agreement for BV were +/- 789 ml or +/- 19.7% of the average BV of 4008 ml. It is concluded that bioelectrical impedance plethysmography using a single frequency can be used for the estimation of ECS and BV. The wide limits of agreement, however, may limit its used in clinical practice.

Adult↗
PubMed1991

T-DNA gene 5 of Agrobacterium modulates auxin response by autoregulated synthesis of a growth hormone antagonist in plants.

Oncogenes carried by the transferred DNA (T-DNA) of Agrobacterium Ti plasmids encode the synthesis of plant growth factors, auxin and cytokinin, and induce tumour development in plants. Other T-DNA genes regulate the tumorous growth in ways that are not yet understood. To determine the function of T-DNA gene 5, its coding region was expressed in Escherichia coli. Synthesis of the gene 5 encoded protein (26 kDa) correlated with a 28-fold increase in conversion of tryptophan to indole-3-lactate (ILA), an auxin analogue. Expression of chimeric gene 5 constructs in transgenic tobacco resulted in overproduction of ILA that enhanced shoot formation in undifferentiated tissues and increased the tolerance of germinating seedlings to the inhibitory effect of externally supplied auxin. Promoter analysis of gene 5 in plants revealed that its expression was inducible by auxin and confined to the vascular phloem cells. cis-regulatory elements required for auxin regulation and phloem specific expression of gene 5 were mapped to a 90 bp promoter region that carried DNA sequence motifs common to several auxin induced plant promoters, as well as a binding site for a nuclear factor, Ax-1. ILA was found to inhibit the auxin induction of the gene 5 promoter and to compete with indole-3-acetic acid (IAA) for in vitro binding to purified cellular auxin binding proteins. It is suggested therefore that ILA autoregulates its own synthesis and thereby modulates a number of auxin responses in plants.

Base Sequence↗
PubMed1990

Extracellular space, blood volume, and the early dumping syndrome after total gastrectomy.

Extracellular space and blood volume were measured using 82Br dilution and 51Cr-tagged erythrocytes in 24 tumor-free patients after total gastrectomy. Eleven of the patients suffered from early dumping. Age, blood volume, and extracellular space were significantly smaller in dumpers (P less than 0.05). The dumping score could be predicted by a multiple regression model considering blood volume per lean body mass and extracellular space (r = 0.637; P = 0.0039). Rapid (t1/2 less than 360 seconds) emptying of the gastric substitute, assessed using a 99Tc-labeled solid test meal, was significantly associated with dumping in addition to extracellular space and blood volume (r = 0.876; P = 0.0018). Both rapid emptying and a narrow extracellular space seem to contribute to the early dumping syndrome.

Blood Volume↗
PubMed1989

High-frequency T-DNA-mediated gene tagging in plants.

An insertion element [transferred DNA (T-DNA)], transferred by soil agrobacteria into the nuclear genome of plants, was used for induction of gene fusions in Arabidopsis thaliana, Nicotiana tabacum, and Nicotiana plumbaginifolia. A promoterless aph(3')II (aminoglycoside phosphotransferase II) reporter gene was linked to the right end of the T-DNA and transformed into plants along with a plasmid replicon and a selectable hygromycin-resistance gene. Transcriptional and translational reporter gene fusions were identified by screening for APH(3')II enzyme activity in diverse tissues of transgenic plants. The frequency of gene fusions, estimated by determination of the copy number of T-DNA insertions, showed that on average 30% of T-DNA inserts induced gene fusions in Arabidopsis and Nicotiana. Gene fusions were rescued from plants by transformation of the T-DNA-linked plasmid and flanking plant DNA into Escherichia coli. By dissection of gene fusions and construction of chimeric genes, callus- and root-specific promoters were identified that showed an altered tissue specificity in the presence of a 3'-downstream-located 35S promoter. Transcript mapping of a gene fusion and expression of a non-frame transcriptional fusion of bacterial luciferase luxA and luxB genes demonstrated that dicistronic transcripts are translated in tobacco.

Base Sequence↗
PubMed1989

[Health-related evaluation of plant protective agents in drinking water].

Crop protection products are anthropogenous substances that should have no place in drinking water. Some of them are long-lived, can accumulate and are poorly biodegradable and many of them are not so harmless to human health as would be desirable or necessary. Accordingly, Federal German legislation provides for limit values of crop protection products close to the identification limit. Although it does not appear justified to close down waterworks effective 1 October 1989 if these limit values are exceeded, it must be carefully considered up to which concentration--depending on the individual substance--special permissions can be granted for a limited period of time. It seems that such concentrations should preferably be in accordance with general food legislation. Recommendations will be shortly issued by the Federal Health Ministry. The fact that special permissions are at all under consideration to prevent complete closing down of water supply reservoirs should sound a note of warning to all concerned, including crop protection product users and the relevant Government agencies issuing special permits.

Germany, West↗
PubMed1978

[Water and potassium metabolism in functional disturbances of the thyroid gland (author's transl)].

Total body water, extracellular water (bromide space), plasma volume and total body potassium were evaluated in hypothyroid (n = 24) and hyperthyroid (n = 18) patients and in controls (n = 10). Whereas the relative extracellular water was the same in all groups investigated, the relative intracellular water was found to be reduced in hyperthyroidism and increased in hypothyroidism (p less than 0.05). As to plasma volume there were no significant differences. A negative correlation between total body potassium and functional disturbance of the thyroid (T4) is thought to be attributable to an alteration of the lean body mass.

Blood Volume↗