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Biomedical subjects

J Römer

Publications and source records attributed to J Römer.

At least 19 recordsLinked to original sources

[Rupture of a splenic aneurism in an emergency situation].

We report on a 36 year old patient who collapsed at home and was resuscitated by prehospital medical emergency services. He presented on scene unconscious with severe ST-elevations on the ECG and hardly palpable pulses. His previous medical history included only idiopathic hypertension and his professional background as manager of a company was associated with high stress levels. The prehospital diagnosis was myocardial infarction with cardiogenic shock. A hypovolemic shock was excluded from the differential diagnosis because of the age of the patient, lack of a precipitating trauma and inconsistent symptoms. The patient died after terminating prolonged resuscitation. A post mortem showed as cause of death the rupture of a splenic artery aneurysm. We emphasize that a cardiovascular collapse in a young patient without specific history or trauma still can be caused by hypovolemic shock due to intra-abdominal or -thorac bleeding.

Adult↗

Swedish-German actinide migration experiment at ASPO hard rock laboratory.

Within the scope of a bilateral cooperation between Svensk Kärnbränslehantering (SKB) and Forschungszentrum Karlsruhe, Institut für Nukleare Entsorgung (FZK-INE), an actinide migration experiment is currently being performed at the Aspö Hard Rock Laboratory (HRL) in Sweden. This paper covers laboratory and in situ investigations on actinide migration in single-fractured granite core samples. For the in situ experiment, the CHEMLAB 2 probe developed by SKB was used. The experimental setup as well as the breakthrough of inert tracers and of the actinides Am, Np and Pu are presented. The breakthrough curves of inert tracers were analyzed to determine hydraulic properties of the fractured samples. Postmortem analyses of the solid samples were performed to characterize the flow path and the sorbed actinides. After cutting the cores, the abraded material was analyzed with respect to sorbed actinides. The slices were scanned optically to visualize the flow path. Effective volumes and inner surface areas were measured. In the experiments, only breakthrough of Np(V) was observed. In each experiment, the recovery of Np(V) was < or = 40%. Breakthrough of Am(III) and Pu(IV) as well as of Np(IV) was not observed.

Actinoid Series Elements↗

Characterization of Gorleben groundwater colloids by atomic force microscopy.

Groundwater colloids from the Gorleben site (Lower Saxony, Germany) are characterized in the presence of Eu(III) by tapping-mode atomic force microscopy (AFM) with phase contrast imaging. Using a liquid cell the method allows investigations of samples being in contact with aqueous solution. This ensures that complex structures are kept in their native hydrated state. Different types of colloids and aggregates are found by AFM, e.g., spherical particles, fibrous structures, and structures which appear to be hollow. A partial coating of the edges of clay particles with humic colloids can be assumed from phase contrast images. Therefore, aquatic colloids and their aggregates found in Gorleben groundwater can be characterized as a complex mixture of components, which may influence the migration of groundwater contaminants in different processes.

Colloids↗

Distribution of estrone sulfatase in rat brain determined by in vitro autoradiography with 16alpha-[18F]fluoroestradiol-3,17beta-disulfamate.

16Alpha-fluoroestradiol-3,17beta-disulfamate (FESDS) strongly inhibits estrone sulfatase (ES), an enzyme which is also present in the brain. The enzyme is probably involved in important regulatory functions of neurosteroids which may be disturbed in certain brain diseases. In the present study, [18F]FESDS was used to measure the amount of ES in various rat brain regions using quantitative in vitro autoradiography. The obtained values vary between 0.29 pmol (mg protein)(-1) (pons) and 11.5 pmol (mg protein)(-1) (striatum). They are positively correlated with the enzyme activity measured in homogenates of the corresponding regions. Because this radiotracer binds also to carbonic anhydrase in the brain it is only of limited use for in vivo imaging studies.

Adenocarcinoma↗

Distribution of 16alpha-[18F]fluoro-estradiol-3,17beta-disulfamate in rats, tumour-bearing mice and piglets.

Based on a high affinity to the enzyme estrone sulfatase (ES), 16alpha-[18F]fluoroestradiol-3,17beta-disulfamate ([18F]FESDS) has been suggested as a potential PET radiotracer for imaging steroid-dependent breast tumours. The distribution of [18F]FESDS was studied in rats, tumour-bearing nude mice and piglets. In all species evidence for binding to a second target, the enzyme carbonic anhydrase (CA), was obtained. ES and CA inhibitors significantly reduced the radiotracer uptake in various organs but not in tumours. It is concluded that [18F]FESDS binds to ES and CA in vivo but this binding is not strong enough to allow tumour imaging with positron emission tomography (PET).

Animals↗

Automated synthesis of 16alpha-[18F]fluoroestradiol-3,17beta-disulphamate.

After 16alpha-[15F]fluoroestradiol ([18F]FES) has been successfully prepared in an automated module, the synthesis of 16alpha-[18F]fluoroestradiol-3,17beta-disulphamate ([18F]FESDS) is described as a module-assisted one-pot procedure which can provide 10GBq [18F]FESDS with a radiochemical purity better than 99%. The procedure is reliable and reproducible and requires a time of about 90 min. Because of its high sulphatase-inhibitory effect [15F]FESDS is thought to be a new PET tracer to image sites of high sulphatase activity.

Arylsulfatases↗

Phagocytosis and killing of Mycobacterium avium complex by human neutrophils.

Organisms belonging to the Mycobacterium avium complex (MAC) cause life-threatening bacteremia in immunocompromised patients. Monocytes and macrophages are thought to be responsible for ingestion and killing of MAC. However, it has been suggested that neutrophils may play a role in the early immune response to MAC infection. Here, neutrophils in autologous plasma were incubated (at 0 and 37 degrees C) with M. avium labeled with Auramine O, a potent fluorochrome. Neutrophil phagocytosis was measured by flow cytometry. Neutrophils incubated at 37 degrees C showed an increase in fluorescence over time with a maximum at 15 min, whereas neutrophils on ice showed no time-dependent increase in FL1. At 15 min Fl 1 at 37 degrees C was twice as high as FL1 at 0 degrees C. Examination under the fluorescent microscope showed multiple intracellular fluorescent mycobacteria. Results in nine independent experiments showed time-dependent decrease of colony-forming units in neutrophil-associated live M. avium. Significant killing was observed within 30 min and was complete by 120 min. Observation by electron microscopy clearly confirmed the presence of intraphagosomal MAC, both intact and with evidence of degradation. These data demonstrate that MAC is rapidly phagocytized and killed by human neutrophils. The newly established flow cytometry method should be useful in further studies of neutrophil function and of the role of G-CSF and other cytokines in MAC disease.

Adult↗

[Bovine serum albumin conjugates of the new progestagen dienogest, synthesis and immunogenic properties].

In order to develop a radioimmunoassay for the new progestagen dienogest (STS 557, 17 alpha-cyanomethyl-17 beta-hydroxy-estra-4,9-dien-3-one), bovine serum albumin (BSA) conjugates of STS 557-3-carboxymethyloxime and of STS 557-11-hemisuccinate were synthesized as antigens for the production of antisera. It was proved that an excess of isobutylchlorocarbonate in the coupling reaction using the "mixed anhydride method" results in an acylation of free NH2-groups in the BSA. By the immunization of rabbits with the STS 557-antigen-antisera of high specificity and affinity to STS 557 were produced. Endogenous steroids show no cross reaction with the STS 557-antisera. Steroids with a 17 alpha-CH2CN-group, being obtained by chemical synthesis or microbial transformation, compete with STS 557 for the binding positions of the antibodies to a different extent.

Animals↗

Characterization of various immunoglobulin preparations for intravenous application. I. Protein composition and antibody content.

In this comparative study we investigated 14 immunoglobulin (Ig) preparations for intravenous application; they were prepared by various manufacturers who used either placental or venous blood as the starting material. The pepsin- and plasmin-treated products and a preparation which, according to the manufacturer, was not degraded enzymatically, contained 17-86% of IgG split products. On the other hand, three chemically modified preparations, one preparation treated at pH 4, for products treated with poly(ethylene glycol) (PEG) and one preparation protected by albumin contained 90% or more of non-fragmented IgG. The IgG subclass distribution corresponded to the distribution of subclasses in normal serum only in the nonmodified and not enzymatically degraded preparations. All samples except one contained 0.1 mg/ml IgA or more, all contained only traces of IgM. No product had clinically relevant titers of irregular antibodies against erythrocyte antigens. The content of those antiviral and antibacterial antibodies that were tested for was similar in all preparations. Only the anti-HBs activity exhibited large variations. Some PEG-treated preparations showed an elevated prekallikrein activator (PKA) level, whereas all other preparations contained, if any, only traces of PKA.

ABO Blood-Group System↗

Characterization of various immunoglobulin preparations for intravenous application. II. Complement activation and binding to staphylococcus protein A.

14 immunoglobulin preparations for intravenous use were tested to assess functions of their Fc portion. Inhibition of the hemolytic activity of complement, C1q binding and the interaction of IgG subclasses with Staphylococcus protein A were investigated. Complement studies were done on both the ready-for-infusion and the heat-aggregated preparations. Three groups of products could be distinguished: (1) Enzymatically and chemically treated products were devoid of complement-activating capacity, both when tested and ready-for-infusion and as heat-aggregated preparations. The chemically treated preparations showed atypical binding properties to Staphylococcal protein A. (2) The poly-(ethylene glycol) (PEG)-treated preparations and the untreated reference activated complement before and after heat-aggregation. (3) The albumin protected and the pH 4-treated product did not spontaneously activate complement in the ready-for-infusion state but did so after heat-aggregation. These results suggest that only the albumin-protected and the pH 4-treated products can be expected both to be well tolerated when given intravenously to high-risk agammaglobulinemic patients and to exhibit normal Fc functions in vivo.

Complement Activating Enzymes↗

Assay of anticomplementary activity in solutions of immunoglobulins.

A method of estimating the inactivation of complement by immunoglobulins, based on a hemolytic assay, is described. During a three year period of routine assays the investigation of standard immunoglobulin solutions of high and low anticomplementary activity confirmed the reliability of the method. Since the activity of complement is largely dependent on the ionic strength, the salt concentration of the test solution must be carefully adjusted. The specific complement inactivation per gram immunoglobulin CI50/g is proposed as a parameter to compare the anticomplementary activity of immunoglobulin solutions.

Animals↗