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Biomedical subjects

M Böck

Publications and source records attributed to M Böck.

51 records · Page 3Linked to original sources
PubMed1990

[Thrombocyte crossmatching: clinical experience with the Capture P-test].

A commercially available solid phase red cell adherence test (Capture P) for platelet crossmatching was tested. The specificity of the test is 94.8%, the sensitivity 47.9%. Whereas the predictive value for negative results is low (52.9%), the predictive value for positive results was calculated as 93.8%. Therefore, the Capture P test seems to be useful for the exclusion of incompatible single donor platelet concentrates from transfusion. When negative results are obtained, however, no precise prediction of the transfusion success can be made.

Blood Grouping and Crossmatching↗
PubMed1988

[Antibody detection in emergency transfusions. A comparison of 3 different methods].

We compared the manual Polybrene technique to three standard methods (albumin/Coombs, LISS/Coombs, and enzyme/papain) on 113 red cell antibodies. Polybrene identified 8 antibodies of the Rhesus system missed by standard methods, whereas 3 antibodies could only be detected by the standard techniques. Four antibodies were identified only in saline solution at room temperature; 6 were found by use of Polybrene exclusively in the additional Coombs phase. In addition, 61 antibodies were tested by 4 different LISS. No considerable differences in the quality of the various LISS were seen. The manual Polybrene test appears to be suitable for crossmatching and rapid antibody identification in emergency situations.

Blood Group Antigens↗
PubMed1986

Cardiac ventricular beta 2-adrenoceptors in guinea-pigs and rats are localized on the coronary endothelium.

In mammalian heart tissue beta 2-adrenoceptors are known to coexist with beta 1-adrenoceptors. In the present study, evidence that beta 2-adrenoceptors in guinea-pig and rat ventricles are primarily localized on the coronary endothelium is provided by competition binding studies with the subtype-selective beta-adrenoceptor antagonists ICI 89.406 (beta 1-selective) and ICI 118.551 (beta 2-selective) on four different plasma membrane preparations. (1) Following density gradient centrifugation of cardiac ventricular microsomes from rats or guinea-pigs, endothelial plasma membranes migrated at slightly higher density than the sarcolemmal membranes, as verified by endothelial (angiotensin converting enzyme) and sarcolemmal markers (adenylate cyclase, [3H]ouabain binding). At the activity peak of angiotensin converting enzyme, the relative amount of beta 2-adrenoceptors in guinea-pigs and rats was 25% and 65%, respectively. (2) On sarcolemmal membranes corresponding to the activity peak of adenylate cyclase, beta-adrenoceptors consisted of the beta 1-type exclusively (guinea-pig), or to at least 90% (rat). (3) Cultures of coronary endothelial cells derived from guinea-pigs revealed only beta 2-adrenoceptors. (4) Isolated guinea-pig cardiomyocytes contained only beta 1-adrenoceptors, a finding recently established in rat myocytes as well.

Animals↗
PubMed1985

[Recent knowledge about the metabolic regulation of coronary circulation, with a contribution on adenine nucleotide metabolism of coronary endothelial cells].

The adenosine hypothesis in its original form neglects other myocardial tissues besides the predominant cardiomyocyte compartment. We could, however, demonstrate that the coronary endothelium comprises a metabolically very active adenosine and adenine nucleotide compartment of the heart, and functions as an impermeable metabolic barrier for interstitially or intravascularly accumulating adenosine if the vasoactive nucleoside is present at concentrations less than 10(-6) M. As a consequence, the vasodilatory action of intracoronarily applied adenosine cannot result from a direct action on the smooth muscle cells of the arterioles, but must be mediated by the endothelium. Since high molecular weight derivatives of adenosine, which are clearly confined to the coronary system, can also induce a very prompt coronary flow increase when applied intravascularly, smooth muscle relaxation must be triggered by an extracellular adenosine receptor at the luminal surface of the endothelium. According to preliminary pharmacological studies, this receptor belongs to the A2-type and thus stimulates the endothelial adenylate cyclase system. On the basis of our findings it is evident that with respect to the vasodilating effect of adenosine one has to distinguish between its action from the interstitial space directly via the putative receptor at the surface of the arteriolar smooth muscle cells, and its action from the intravascular space via the newly detected endothelial A2-receptor. It is a matter of further experimentation to determine to what extent both receptor populations actually participate in the metabolic regulation of coronary flow under physiological and pathophysiological conditions.

Adenine Nucleotides↗
PubMed1984

[Comparative studies on the side effects of morphine after peridural, spinal and intravenous administration].

A prospective randomized study was carried out on 29 patients undergoing transurethral prostatectomy. In addition to the regional anaesthetic given for the operation, the patients received either: 1 mg morphine intrathecally (spinal group), 0.05 mg/kg body weight of morphine i.v. (i.v. group), or 0.05 mg/kg body weight epidurally (PDA group). Two of the intrathecal group patients had to be given an antagonist because of clinically relevant respiratory depression. In one of these cases, this depression could be documented by a continuous fall in respiratory minute volume, and an increase in PCO2. In the other, bradypnoea and vomiting developed within a few minutes of injection. The presence of a central action of intrathecal and epidural opiates was indicated by the significant increase in reaction time found. In the two instances of respiratory depression, the CSF morphine concentration 24 hrs after injection was markedly lower (0 and 18 ng/ml respectively) than in unaffected patients. It must therefore be assumed that the respiratory depression was caused by a more rapid cephelad transport than that occurring in normal cases.

Aged↗
PubMedDate not supplied

Binding of [3H]ouabain to endothelial cells derived from various vascular beds.

Binding experiments were performed with [3H]ouabain on plasma membranes derived from several types of isolated and cultivated endothelial cells. Identical saturation curves for [3H]ouabain binding to endothelial cells from pig aorta, caval vein, and pulmonary artery were obtained with a dissociation constant (KD) of 3.29 +/- 0.31 nmol/l and a binding capacity (Bmax) of 5.22 +/- 0.12 pmol/mg protein. On guinea-pig coronary endothelial cells, saturation of [3H]ouabain revealed much lower affinity (KD 95 +/- 15 nmol/l, Bmax 2.08 +/- 0.09 pmol/mg protein). All Scatchard plots were linear, indicating a homogeneous class of binding sites. In competition experiments, cardiac glycosides and their aglycons displaced the radioligand with a structure-activity relationship typical for interaction with Na+/K+-ATPase (proscillaridin A greater than ouabain greater than digoxin greater than g-strophanthidin greater than digoxigenin greater than dihydrodigoxin); in particular, removal of the sugar moiety results in considerable reduction of affinity. Furthermore, K+ displayed a steep inhibition curve with a half-maximal inhibitory constant of 2 mmol/l. All these findings suggest the presence of endothelial ouabain receptors linked to Na+/K+-ATPase. However, direct measurement of this enzyme was not possible due to an extremely high Mg2+-ATPase activity.

Animals↗
PubMedDate not supplied

The coronary endothelium: a highly active metabolic barrier for adenosine.

Cultured coronary endothelial cells and the coronary endothelium of isolated perfused guinea-pig hearts are characterized by a very active adenosine and adenine nucleotide metabolism. Adenosine applied to the endothelium at low concentrations is avidly metabolized and preferentially incorporated into different nucleotide pools--only a minor amount is degraded to uric acid. Physiologically, the coronary endothelium therefore functions as an impermeable metabolic barrier for interstitially or intravascularly accumulating adenosine. Only at concentrations greater than or equal to 10(-6) M adenosine can pass the endothelial barrier. As a consequence, the vasodilatory action of adenosine formed in or administered into the coronary system cannot be induced by a direct association of the nucleoside with the putative adenosine receptor of the arteriolar smooth muscle cells, but must be mediated by the endothelium. High molecular weight derivatives of adenosine, clearly confined to the coronary system, can also induce a coronary dilation. The endothelium-mediated smooth muscle relaxation is therefore obviously due to triggering of an extracellular adenosine receptor at the luminal surface of the endothelium. Since this process is accompanied by a rapid and pronounced activation of the adenylate cyclase system, the endothelial receptor conforms to an A2-type. According to our results it is necessary to reconsider qualitative and quantitative facets of the adenosine hypothesis of metabolic regulation of coronary blood flow, which--in its original formulation--exclusively centers on the cardiomyocyte metabolism. With respect to the vasoactivity of adenosine one obviously has to distinguish between its action from the interstitial space directly via the myocyte receptors of the vessel wall, and/or its action from the intracoronary space via the newly detected endothelial A2-receptor. More information is needed to determine the extent to which both receptor populations actually participate in the metabolic regulation of coronary flow under physiological and pathophysiological conditions.

Adenine Nucleotides↗
PubMedDate not supplied

Cryopreservation of human platelets with dimethyl sulfoxide: changes in biochemistry and cell function.

BACKGROUND: The shelf life of liquid-stored platelet concentrates is limited to 5 days. Therefore, much work has been carried out in an attempt to establish the optimum method for cryopreservation. Among the various cryoprotectants, dimethyl sulfoxide (DMSO) has been shown to be the most effective. However, DMSO-frozen platelets are characterized by a number of cell lesions. This report describes metabolic and functional changes that should give rise to some concern about the functional integrity of these cells. STUDY DESIGN AND METHODS: Single-donor platelet concentrates were frozen in liquid nitrogen by use of DMSO (5%). After thawing, the cells were washed and resuspended in autologous plasma. Before, during, and after the freezing process, samples for analysis of metabolic measures (e.g., pH; calcium, potassium, and lactate dehydrogenase concentrations; plasma complement factors) and functional measures (e.g., aggregometry, in vitro bleeding time, alpha-granule membrane protein-140 expression) were taken. RESULTS: Mean platelet volume increases during the deep-freezing process. Potassium, calcium, and lactate dehydrogenase are released from the intracellular space to the extracellular space. A strong activation of complement, which is mainly due to the addition of DMSO, is observed. Platelets become activated as indicated by the expression of alpha-granule membrane protein-140. Accordingly, decreased platelet function can be observed. CONCLUSION: DMSO-frozen platelets are characterized by several metabolic and functional changes. Although these cells have been shown to exert hemostatic effects in vivo, it is conceivable that those effects could be improved by further development of platelet-freezing techniques.

Blood Platelets↗
PubMedDate not supplied

Influence of antibiotics on posttransfusion platelet increment.

BACKGROUND: Fever has been identified as a major cause of platelet refractoriness. However, it is regularly attended by the administration of antibiotics, and thus it cannot be determined whether fever, the administration of antibiotics, or both are responsible for the reduced platelet increment. The present study was undertaken to discern the effect of body temperature and antibiotics on transfusion success. STUDY DESIGN AND METHODS: Single-donor platelet transfusions (n = 400) were monitored retrospectively. Besides other influencing factors (e.g., spleen size, number of previous transfusions, diagnosis, bone marrow transplantation), body temperature and the administration of antibiotics were documented from the patients' records. To distinguish the effects of fever and antibiotics, a general mixed model of variance was used for analysis. RESULTS: Besides the well-known factors of splenomegaly, hepatomegaly, bone marrow transplantation, and pretransfusion storage time, both body temperature and antibiotics independently reduced the corrected count increment. Among the various antibiotics, amphotericin B, ciprofloxacin, and vancomycin had the greatest influence. CONCLUSION: The administration of antibiotics has a negative effect on the corrected count increment, independent of the presence of fever. Besides amphotericin B, which has previously been shown to influence the corrected count increment, vancomycin and ciprofloxacin reduce it significantly. Because these antibiotics are widely used in patients with bone marrow failure, these observations should be proven by further prospective in vivo and in vitro studies.

Adolescent↗
PubMedDate not supplied

Single-donor platelet concentrates: changes of surface glycoproteins during storage.

Storage of single-donor platelet concentrates is currently limited to 5 days. During this period, however, numerous morphologic and biochemical changes have been observed. These changes result in functional impairment of stored platelets. The present study describes increased binding of a monoclonal antibody against GMP 140 on the surface of stored single-donor platelets revealing an activation process. In contrast, binding of monoclonal antibodies directed against glycoprotein complex (GP) IIb-IIIa and ligand-induced binding site (LIBS1) is slightly diminished during storage. When platelets are stimulated with ADP GMP 140, GP IIb-IIIa, and LIBS1 are expressed to a higher extent than on the surface on nonstimulated platelets. The quantity exposed, however, depends upon the storage time. It is significantly reduced when platelets are stored for longer than 1-2 days. The present data indicate that storage of single-donor platelet concentrates affects fibrinogen binding, cell to cell cohesion, and release reaction. The results are in good agreement with conventional aggregation and in vitro bleeding time measurements.

Antigens, CD↗
PubMedDate not supplied

Influence of blood transfusion on recurrence, survival and postoperative infections of laryngeal cancer.

Clinical and experimental studies indicate, that blood transfusion can modify the recipient's immune system. While beneficial to renal allograft survival, these immunomodulating effects may, however, prove detrimental to cancer patients. Recently, an adverse relationship between blood transfusion and cancer recurrence was reported in colon, lung, breast, kidney and gastric cancer. Moreover, a higher postoperative infection rate was observed when blood units were administered intraoperatively. We retrospectively reviewed the records of 174 patients with squamous cell carcinoma of the larynx undergoing curative resection between 1979 and 1985. One hundred and forty-one patients received blood transfusions, 33 did not. Recurrence rate (16.7%) was significantly related to clinical stage (p = 0.008) and lymph node status (p = 0.000); cumulative survival time depended significantly on clinical stage (p = 0.003), lymph node status (p = 0.004) and tumor size (p = 0.017). In contrast, when corrected for these baseline prognostic factors, no significant correlation could be detected between blood transfusion and cancer relapse. Also, survival time did not depend on blood transfusions. No correlation could be found between postoperative infection rate and intraoperative application of blood transfusion (p = 0.694). The present study does not support the hypothesis that blood transfusion adversely affects the prognosis of patients with laryngeal cancer. It indicates, that risk factors other than blood transfusion have a greater influence on recurrence and survival time.

Adult↗