PubMed Health⌕ Search

Biomedical subjects

J U Wieding

Publications and source records attributed to J U Wieding.

18 recordsLinked to original sources
PubMed1992

Determination of soluble fibrin: a comparison of four different methods.

The determination of soluble fibrin (SF) in plasma was compared using four different methods. The SF-ELISA immunologically measures the concentration of desAA- and desAABB-fibrin while the SF-tPA-test is based on activation of plasminogen by tissue plasminogen activator (tPA) in the presence of fibrin; the SF-PS-turbidimetry assay relies on the protamine sulphate (PS) -induced aggregation of fibrin in plasma whereas the SF-erythrocyte-agglutination-test (SF-EAT) detects soluble fibrin by its aggregation with fibrin monomers attached to test erythrocytes. Soluble fibrin was generated in vitro by addition of thrombin or ancrod to plasma. In these experiments the soluble fibrin values of the four methods correlated well with each other and with the fibrinopeptide A release, especially in ancrod-induced fibrinogen turnover (r greater than 0.93). This high correlation is remarkable, considering the fact that the methods are based on different principles. Detection of thrombin-induced soluble fibrin was more sensitive; differences between ancrod and thrombin action were observed as well, probably due to different forms of soluble fibrin. A delayed increase of SF-PS-turbidimetry values in particular during the thrombin action can be attributed to a lack of detectable aggregation of soluble fibrin at low concentrations due to its solubility in plasma. Subsequently, soluble fibrin was measured in samples from patients. The SF-ELISA and SF-tPA-test were highly sensitive and correlated better than the other methods with each other, but all correlations were less satisfactory compared with the in vitro studies. These weaker correlations might be explained by the heterogeneity of soluble fibrin determined by inter- and intraindividually varying concentrations of fibrinogen and its different derivatives in plasma samples from patients. All methods provided reliable results with differences in sensitivity, specificity and practicality. The SF-tPA-test, SF-PS-turbidimetry, and SF-EAT are practical methods for routine use whereas the SF-ELISA is a highly reliable and by far the most sensitive and specific method thus offering new insights into pathogenesis of fibrinaemia and related diseases.

Enzyme-Linked Immunosorbent Assay↗
PubMed1992

[Initial experiences with methylene blue virus inactivated fresh frozen plasma: results of a clinical and in vitro study].

Methylene blue (MB) has recently been introduced to inactivate viruses in single donor fresh frozen plasma (FFP) units. In the first clinical study 519 units of MB-treated FFP were given to 103 patients. No specific clinical side effects with adverse reactions were recorded. However, after thawing, clots were observed in 9 of the first 110 units, although the medical staff had thawed the MB-FFP in exactly the same manner as the conventional FFP in which clots are extremely rare. The possible effects of methylene blue were investigated by subsequent in vitro experiments: Methylene blue together with light led to generation of fibrin(ogen) derivatives which have an increased tendency for aggregation but cannot be normally clotted by thrombin and even seem to interfere with normal fibrin polymerization. Inadequate conditions during plasma preparation such as long illumination or temperatures above 40 degrees C enhanced the generation of these fibrin(ogen)-derivatives. In addition, special requirements for producers and users of MB-FFP and further investigations are necessary in order to prevent complications.

Blood Preservation↗
PubMed1991

[Comparison of 4 plasmapheresis procedures].

In recent years the collection of plasma has been increasingly carried out by apparative plasmapheresis. In the University Hospitals of Göttingen and Würzburg the plasmapheresis machines PCS from Haemonetics, Autopheresis-C from Baxter, as well as Plasmapur-Monitor from Organon-Teknika, were compared with each other and with the conventional centrifugation of blood bags; experiences in routine use were complemented by specific studies. Altogether, the apparative methods distinguished themselves through a high quality of retransfused blood and collected plasma. Furthermore, practicability, donor compatibility and donor safety resulted in good acceptance by both donors and staff.

Blood Cell Count↗
PubMed1991

[Neuronal nets].

Neural networks are used as models of cognitive systems. On the basis of results from brain research, the processing of knowledge and information can be conceived as occurring through parallel interaction of multiple but simple and uniform processor elements in a network structure. In these 'neural networks' knowledge is stored in a distributed way throughout the network and subjected to parallel processing. According to Hebb's concept of synaptic plasticity, the process of learning is based on the strengthening of the links between the processing elements. The implementation of network models in electronic data processing systems allows for simulation of cognitive phenomena such as learning and forgetting or abilities such as recognition of acoustical or optical patterns, in a more efficient way than conventional computer programming. Neural network modelling can help to understand the abilities and disorders of the brain.

Cognition↗
PubMed1990

Application of a network structure in a knowledge-based system for medical diagnostics.

Systems supporting diagnostic decision making have been designed more often on the base of production rules than on semantic nets. One reason for that might be that concepts to process information on the latter structures are still rare. In this study the application of a semantic net is described. Via creation of various views, different sets of information are defined, depending on their meaning in the semantic net. Projections, which are in general a combination of mappings and set operations, are used to infer a set of information from another. The developed system was written in Pascal, the semantic net was implemented using a network-like pointer structure. The concept has been used to develop PROJECTOR, an expert system for differential diagnosis based on a semantic net. The structure has turned out to be fast and compact enough to allow large amounts of data to be handled easily even with a personal computer.

Diagnosis, Computer-Assisted↗
PubMed1990

[Comparison of 4 procedures in plasmapheresis: studies of modifying the hemostasis potential].

The separation of plasma using the systems "Plasmapur Monitor" (Fa. Organon), "Autopheresis-C" (Fa. Baxter) and "PCS" (Fa. Haemonetics) was compared with the conventional blood bag centrifugation. In 16 apheresis per method, several parameters with the main focus on blood coagulation were examined in addition to other criteria. Compared to conventional centrifugation of blood bags, the plasma separation machines led to an only slight activation of the coagulation system, which seems to be negligible for donors as well as recipients. Furthermore, a decrease of coagulation factors and inhibitors in the collected plasma was most pronounced using bag centrifugation. Beyond this, particularly in apheresis systems with plasma filtration the low number of remaining cells meets the aim to reach a high quality of transfused plasma.

Blood Coagulation Tests↗
PubMed1990

Development of a computer-aided reference system for differential diagnostics support.

In a situation of uncertain diagnosis, physicians may spend valuable time consulting relevant literature, often with unsatisfactory results. Therefore, our aim was to develop a computer system which supports differential diagnostics via rapid and comprehensive searches through information in literature. Based on entered signs and symptoms our prototype is able to offer probable diagnoses. Subsequently, further examinations and tests are suggested to confirm or exclude a certain disease. Thus, the final diagnosis is made gradually by differentiation of possible diseases. Our first attempt consisted in representing knowledge in a rule-based PROLOG system. However, because nearly all information for a sign-oriented differential diagnosis can be represented with very few relations only, we turned to a fact-oriented representation of signs and diseases. Access was possible via PROLOG or an imperative programming language. The index-sequential access on a fact-oriented representation of knowledge was suitable to manage a large knowledge base, which is necessary for a thorough differential diagnosis. A pointer structure was recently examined in order to handle different object-to-object relations. Efficient information processing is now possible which provides short response times using even broad knowledge bases.

Diagnosis, Computer-Assisted↗
PubMed1990

[Anesthesiologic and intensive care aspects of severe pre-eclampsia with HELLP syndrome].

From 1984 to 1988 22 patients with preeclampsia and HELLP syndrome were treated in our ICU. The HELLP syndrome is defined as preeclampsia complicated by thrombocytopenia, hemolysis and disturbed liver function. 3 patients developed a severe DIC with consumption of hemostatic potential. One patient died in multiorgan failure having a consumption coagulopathy, liver rupture and renal failure. To prevent severe hemostatic complications, it is essential to start therapy of DIC as soon as possible by inhibition of the activated coagulation system. Bleeding caused by blood coagulation disorders can occur spontaneously and during operative treatment. Epidural or spinal anaesthesia should be avoided in patients with HELLP syndrome. Because of severe complications such as respiratory failure, diffuse bleeding caused by DIC and progressive deterioration of the renal and liver function in most of the cases, patients with HELLP syndrome require a close cooperation between obstetrics and anesthesist.

Acute Kidney Injury↗
PubMed1989

[Diagnosis of disseminated intravascular coagulation: the value of soluble fibrin, D-dimers and fibrin(ogen) split products].

The validity of the fibrin(ogen) derivatives 'soluble fibrin, D-dimers and fibrin(ogen) degradation products' was compared with other parameters in early and sensitive diagnosing of disseminated intravascular coagulation (DIC). In a clinical study 900 patients' samples from separate, defined groups were examined, including course observations of intensive care patients (n = 38) and patients with acute pancreatitis. The fibrin(ogen) derivatives correlated very well with the degree of blood coagulation disturbances: in particular, D-dimers and soluble fibrin proved to be more sensitive in early diagnosis of DIC than other parameters. The SF-PS-turbidimetry demonstrated a good validity and practicality in the quantitative determination of soluble fibrin, but a suitable analyzer is essential. Determination of D-dimers is preferable to that of fibrin(ogen) degradation products (both in the latex-agglutination test) because of the better sensitivity and practicality; even more sensitive results were provided by the D-dimer-ELISA, which is, however, not practical in acute diagnostics. The decrease in protein C was at least equally sensitive as the antithrombin III-levels in indicating the consumption of the hemostatic potential. The decrease of thrombocyte counts and fibrinogen levels could first be detected in a later stage of DIC. In conclusion, D-dimers and soluble fibrin can improve the DIC diagnostics, making them more reliable; additionally, antithrombin III and possibly protein C deserve further consideration, although the fibrin(ogen) derivatives are apparently of greater importance.

Acute Disease↗
PubMed1989

Determination of soluble fibrin by turbidimetry of its protamine sulphate-induced paracoagulation.

Protamine sulphate-induced aggregation of soluble fibrin causes an increase of turbidity in the plasma sample, which can be measured by means of kinetic turbidimetry. A method was developed which is sufficiently sensitive for the determination of soluble fibrin in plasma without interfering with the sensitivity for fibrinogen. The performance of the assay was studied by analysing plasma samples with high concentrations of fibrinogen and soluble fibrin at different pH values, at different concentrations of plasma and protamine sulphate, and using different wavelengths and analysis times. Measurement of thrombin-induced fibrinogen-fibrin-transformation by the developed turbidimetric method, gave results that correlated well with the release of fibrinopeptide A. The new protamine sulphate method for turbidimetric determination of soluble fibrin is characterized by its practicability, rapid availability of reproducible, quantitative results, and its economy of reagents and time in single and serial analysis. Therefore it seems well-suited for the routine diagnosis of hypercoagulability with increased fibrinogen turnover.

Blood Coagulation↗
PubMed1985

[The behavior of blood clotting and its inhibitors under long term treatment with 5,6-benzo-alpha-pyrone (coumarin). Double blind study].

The analyses on hemostaseological variables are recorded in connection with blood tests in the course of a double-blind study in 41 patients suffering from chronic venous insufficiency of higher degrees of severity. They were treated in addition to compression measures with two active ingredients, a coumarin (5,6-benzo-alpha-pyrone)/troxerutin combination (Venalot Depot) (n = 20) or benzarone (n = 21) receiving 3 X 2 dragees daily for 6 weeks. Good clinical efficacy and the improvement of symptoms were observed together with almost no side-effects. The coagulation analysis showed no influence of the active principles on the global coagulation or the clotting factors and the inhibitors and factors of the fibrinolysis. In particular there was no phenprocoumon-like effect on the blood clotting system.

Anticoagulants↗
PubMedDate not supplied

[Homologous collagen implants in oral surgery in hemorrhagic patients].

In 154 hospitalized hemorrhagic patients 883 oro-surgical procedures were done under continuous anticoagulation. Human collagen material combined with fibrin adhesive offered a safe hemostatic effect. A total of 12, mostly minor, postoperative bleedings occurred, which did not lead to delayed wound healing. Good tissue tolerance towards both homologous partners and healing by primary intention should be emphasized. These observations are to be corroborated by further clinical trials. Human collagen can make surgical treatment in hemorrhagic patients safer yet.

Blood Coagulation Disorders↗