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V Kretschmer

Publications and source records attributed to V Kretschmer.

At least 55 records · Page 3Linked to original sources
PubMed1996

[Automated blood component collection with the MCS 3p].

OBJECTIVE: Two new protocols for the MCS 3p cellseparator (Haemonetics) for automated collection of blood components were evaluated. MATERIAL AND METHODS: Two units of FFP and one unit of buffy coat free red blood cells (RBC) in additive solution (PAGGS-M) were produced with the D-RBCP protocol. The RBCP-F protocol included additional in-line filtration of the RBC in a closed system. 20 automated blood component collections were performed with each of the two programs. Filtration of the RBC was performed after storage for 24 h at 4 degrees C. Blood cell counts, biochemical characterization of the RBCs (ATP, 2,3-DPG, LDH, HBDH, free Hb, K+, pH) were determined on day 0, 1, 14, 28 and 49. RESULTS AND CONCLUSIONS: Erythroplasmapheresis with both protocols was performed without any technical problems or adverse reactions. The biochemical parameters of the RBC (until 49 days) were as good or even better as with standard preparations (Hb, 2,3-DPG, ATP, LDH, HBDH, hemolysis, K+). Leukocyte and platelet counts in RBC and FFP (D-RBCP) were well within the range requested by German guidelines. Leukocyte reduction of RBC in RBCP-F was adequate but platelets in FFP exceeded the standard values. The extracorporal volume (771 ml in D-RBCP and 632 ml in RBCP-F) was rather large and at least should be adaptable to the donor's individual blood volume.

Blood Banks↗
PubMed1996

[Solid phase technique versus gel centrifugation for detection of erythrocyte antibodies--a prospective study comparison the 2 antibody detection tests].

AIM: To define differences of specifity and sensitivity between a solid phase- and a gel centrifugation test for detection of irregular erythrocyte antibodies. STUDY DESIGN: 3052 blood samples were screened for erythrocyte antibodies (AB) by gel centrifugation [ID-System, (ID) 37 degrees C Bromelin and indirect antiglobulin test with LISS (IAT)] and a solid phase antiglobulin test [Capture-R Ready Screen (CR)] in a prospective study. Identical test cells were used as immobilized monolayer in CR and as 1%-suspension in ID. Additionally, 42 sera with antibodies reacting in both tests were titered geometrically in both techniques. RESULTS: In 79 (2.6%) of all sera tested, irregular erythrocyte antibodies were detected. 64 (81%) of these positive sera were detected by both tests, 73 (92.3%) by ID and 70 (88.4%) by CR. 6 sera with AB (7.6%) were positive only with CR (1 Ce, 1 E, 1 Leb, 1 C, 1 D, 1 Cob) and 9 (11.4%) only with ID (4 Lea, 1 Fya, 1 C, 2 P1, 1 D). Seven AB solely detected in ID only reacted in the bromelin test, besides an anti-Fya, which was an IgM antibody. The titration of IgG antibodies showed a slightly higher sensitivity of the CR (less than one titre step). The ID showed clearly more unspecific reactions (1.1%) than the CR (0.5%). DISCUSSION: The antibody screening with the ID proved to detect more AB than the CR (mainly due to certainly irrelevant "enzyme only" AB). On the other hand, relevant IgG AB were detected more sensitive by the CR. Unspecific reactions appeared clearly more often in ID, predominantly when using the bromelin test. Missing a strong IgM anti-Fya in the CR is certainly a concern because of its assumed haemolytic activity. Therefore CR for antibody screening should always be combined with a method for crossmatching that safely detects IgM antibodies which are relevant for transfusion.

Blood Group Antigens↗
PubMed1996

[Effect of HLA antibodies on the gel centrifugation test].

We studied 39 samples of patients showing unexplainable but reproducibly positive indirect antiglobulin test (IAT) in the gel centrifugation (ID Micro Typing System, DiaMed) and negative auto-control test. Additionally 30 sera with defined red cell antibodies (control group) were tested. In 87.2% HLA antibodies could be found (none in the control group). After platelet absorption, 83.9% of the sera became negative in IAT. When IAT, microlymphocytotoxicity test (MLT) and platelet adhesion fluorescence antiglobulin test (PAFT) were performed with the cells of the same donors in parallel (n = 30) the IAT only became positive with the cells of donors (n = 21 = 70%) who also reacted in the MLT and/or PAFT. The tube test mostly was negative. The immunoglobulin class always was IgG. The specificity of the responsible HLA antibodies could be identified in 13 samples and was anti-HLA-B7, -B17, -A2, -A28 and mixed antibodies of these specificities. We conclude that unexplainable positive reactions in the IAT with gel centrifugation mainly are derived from HLA antibodies of high concentration which obviously play a greater role in the gel centrifugation than in other test methods. In cases of such unexplainable positive reactions the routine use of pooled platelets for absorption is recommended. In addition, test cells for antibody screening and identification by gel centrifugation should be typed at least for Bga (HLA-B7) in order to more easily recognize these irrelevant antibodies.

Blood Group Antigens↗
PubMed1995

Variables influencing the Thrombostat 4000: recommended standardization.

The in vitro bleeding test (IVBT) (Thrombostat 4000) was performed on blood samples from healthy blood donors using a "preliminary standard test." Only one factor of the test procedure was changed each time. We found the following parameters to have a significant influence on the test results: time interval between sampling and testing, diameter of the filter's aperture, capillary diameter, aggregating agents and their concentration, temperature of the blood and cartridges, method of drying the capillaries, the aspiration pressure, and the hematocrit of the blood sample. According to our data, we propose a standard IVBT for routine application and modifications for special diagnostic use.

Adenosine Diphosphate↗
PubMed1995

Desmopressin effect on acetylsalicylic acid impaired platelet function.

The mechanism of DDAVP's shortening of acetylsalicylic acid (ASA) prolonged bleeding times was investigated. Sixteen healthy subjects received two dosages of ASA (100 mg) in 12 hours. Twenty four hours after the first ASA application and again after 32 hours DDAVP was administered intravenously (0.4 micrograms/kg). The trial was terminated after 48 hrs. In between, blood samples were drawn and analyzed for the in vivo bleeding time (Simplate time), in vitro bleeding test (IVBT, Thrombostat 4000), von Willebrand factor antigen (vWf:Ag), Ristocetin cofactor activity (vWf R:Co), plasma beta-thromboglobulin (beta-TG), platelet ATP/ADP, platelet aggregation (collagen, ADP, arachidonic acid), and plasma and platelet thromboxane levels. Simplate time (BT) and IVBT showed an excellent inverse correlation with vWf R:Co (r2 BT = 0.97 and r2 IVBT = 0.99, respectively) during the time when DDAVP was administered, suggesting the involvement of plasma vWF in DDAVP's shortening of the bleeding time. The involvement of plasma thromboxane in this mechanism could be excluded. In addition, DDAVP hampered platelet aggregation tests, possibly due to the inhibition of the release reaction (reduced beta-TG in plasma) by a direct interaction with platelets.

Adult↗
PubMed1995

DDAVP's shortening of the bleeding time seems due to plasma von Willebrand factor.

The pathomechanism of desmopressin (DDAVP) dependent shortening of the acetylsalicylic acid (ASA) prolonged bleeding time (BT) is still unclear. The mechanism of action is supposed to be related to the plasma levels of von Willebrand factor (vWf), but a platelet effect is also discussed. We tried to investigate whether this effect of DDAVP might be due to either plasma vWF or platelets or both. We measured the effect of DDAVP (0.4 micrograms/ml bw in 250 ml 0.9% NaCl) on the Thrombostat 4000 (in vitro bleeding test (IVBT)) after each of 16 volunteers ingested 100 mg of ASA twice. To measure the possible effect of DDAVP on plasma and platelets separately, a mixture of 800 microliters of platelet poor plasma (PPP) or 200 microliters of isolated platelets after DDAVP, respectively, was prepared and the IVBT monitored. Two hundred microliters of PPP or platelets, respectively, served as a control. In an additional experiment, vWF concentrate (12 U/ml) dissolved in 200 microliters of PPP after ASA ingestion, as described above, was added to 800 microliters of citrated whole blood from the same volunteers. The addition of PPP after DDAVP as well as the PPP or PRP after ASA enriched with vWf led to a significant shortening of the IVBT in comparison to the control, indicating that the effect of DDAVP on the prolonged BT seems to be an isolated effect of plasma vWf. By adding platelets we were not able to show a direct effect of DDAVP on platelets.

Adult↗
PubMed1995

The Thrombostat 4000. A sensitive screening test for von Willebrand's disease.

The determination of the bleeding time (BT) is an essential diagnostic tool for von Willebrand's disease (vWD). However, the standardized Simplate BT still displays many variables and disadvantages. The present study reports on the sensitivity of the in vitro bleeding test (IVBT) in 51 vWD cases of different types and severity in comparison to the Simplate BT, and the correlation of both to each other as well as to von Willebrand factor (vWF:RCo) activity. The IVBT was performed in two modifications (2 mmol/L CaCl2 and 4 mmol/L ADP) on the Thrombostat 4000. The IVBT, particularly with CaCl2, showed clearly higher sensitivity than the BT (CaCl2: 84.3%, ADP: 61.7%, CaCl2 + ADP: 86.3, BT: 52.9%). The BT even failed in one patient with severe (type 2B) and in three with moderate vWD. The IVBT only failed in very mild forms of the disease (vW-F:RCo > 25%). In addition, the IVBT with ADP showed a close correlation to the vWF:RCo activity (r2 = 0.73). The significantly lower correlation of the BT with vWF:RCo (r2 = 0.49) was particularly due to the poor results in vWD of type 2 (type 2:r2 = 0.29; types 1 and 3:r2 = 0.61). Finally, BT and IVBT-ADP correlated with each other (r2 = 0.53), a rather good correlation considering that both are complex functional tests. It can be concluded from our study that the IVBT not only may replace the BT for most applications, but is clearly superior to BT for the screening (IVBT-CaCl2) and control of therapy in vWD.

Bleeding Time↗
PubMed1995

Hemostaseological management of urological operations in patients taking aspirin using the Thrombostat 4000.

A clinical study was started in order to examine the suitability of the Thrombostat (in vitro bleeding test) (IVBT) as a diagnostic tool to prevent perioperative bleeding due to aspirin (ASA) and/or platelet function disorders of other origins. This report is based on preliminary data. Eighty three patients who had ingested ASA in the last two weeks and/or with a history of bleeding and/or documented hemorrhagic disorders requiring distinct urological operations, were included in the study. In all patients the IVBT with CaCl2, in addition to common coagulation tests, were performed. Thirteen patients stopped ASA ingestion until IVBT became normal and did not show any increased bleeding tendency. The residual patients were classified by the various operations. The following operation groups were formed: Male genitals (n = 11), inguinal/suprapubic operations (n = 7), transurethral tumor resections of the bladder (TURB) (n = 17), transurethral prostate resection (TURP) (n = 12), tumor nephrectomy (n = 8), radical prostatectomy (n = 9). Thirty six patients with a history of ASA use, but normal IVBT, served as control group (C). Thirty one patients with a history of ASA ingestion had normal in vivo bleeding times (BT) and abnormal IVBT with CaCl2 (A). Seven patients had a bleeding history and/or documented hemorrhagic disorders (B). None of the patients (A) with abnormal IVBT but normal BT displayed clinically relevant bleeding. However, the blood loss was somewhat higher compared to the controls (C), especially in patients with TURB and radical prostatectomy (not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Aspirin↗
PubMed1995

Therapeutic use of phospholipids in thrombocytopenic or thrombocytopathic patients.

Eight thrombocytopenic/pathic patients received an intravenous infusion of phospholipids. In vitro bleeding test (Thrombostat 4000), thrombelastography, and resonance thrombography were performed in order to show the hemostatic effect. In none of the cases did phospholipids exert an effect comparable to platelet transfusion. Two patients, brother and sister, had a severe anaphylactoid reaction after the administration of phospholipids.

Adolescent↗
PubMed1995

Thrombocytopenia-adapted in vitro bleeding test assesses platelet function in thrombocytopenic patients.

Platelet counts do not always reflect the true bleeding risk in chronically thrombocytopenic patients, and the posttransfusion platelet increments do not necessarily demonstrate that therapeutic efficacy. There are no easy and reliable tests yet permitting the determination of platelet function in thrombocytopenic patients. The in-vitro bleeding test (IVBT) with the Thrombostat 4000 proved to be a very sensitive and specific test for the detection of platelet disorders. In order to become suitable for the investigation of thrombocytopenic blood with platelet count between 5 x 10(9)/L and 50 x 10(9)/L, special modifications were necessary. We report on the evaluation of two thrombocytopenia-adapted modifications (TP-IVBT 150/120), first with blood of healthy donors made thrombocytopenic (three experiments with six blood samples each of different platelet concentrations and identical hematocrit) and then in a clinical study on 77 thrombocytopenic patients (69 with bone marrow hypoplasia, eight with autoimmune thrombocytopenia) receiving 267 platelet transfusions. The patients were followed over 15 days on average (1-67 days) by daily examinations (total 1,285 observation days). Most TP-IVBT measurements were carried out in triplicate, using the modification with the 120-microns filter (TP-IVBT 120) because it proved to be superior to the other modification. Additionally, cell counts, hematocrit, body temperature, platelet volume, platelet distribution width, expression of CD 36, 41a, 42b on platelets, Simplate bleeding time, and detailed analysis of bleeding signs were performed for the calculation of a bleeding score. There was a close correlation between TP-IVBT and platelet counts with thrombocytopenic normal blood (r2 = 0.81-0.94). This indicated the suitability of this test modification to examine platelet function in thrombocytopenic patients. The clinical study showed that the TP-IVBT helped at least to determine the platelet-related bleeding risk in thrombocytopenic patients. It allowed differentiation between hypoplastic and autoimmune thrombocytopenia in most cases. In addition, significant differences in platelet function of various diseases and of different bone marrow regeneration could be demonstrated. The TP-IVBT is well-suited for the control of platelet transfusion efficacy and may replace the in-vivo bleeding time in most cases. On the other hand, the test still shows too much of a variation and involves too much labor and cost for routine application.

Bleeding Time↗
PubMed1995

Influence of HPA-1a and HLA antibodies on primary hemostasis.

The influence of platelet specific and HLA antibodies was investigated on primary hemostasis by the in vitro bleeding test (IVBT) (Thrombostat 4000). Seven of 12 plasmas with HPA-1a (P1A1) antibodies and two with antibodies against glycoprotein Ib/IX significantly inhibited the IVBT of normal, cross-match-positive donor blood. This correlated with a significant increase of GMP-140 (CD 62) on the platelets, determined by flow cytometry. These results agree with the literature showing both activation and inhibition of platelet function by platelet specific antibodies. On the other hand, HLA antibodies showed a similar platelet activation (shortening of occlusion time and decrease in blood volume in the IVBT, increase of CD 62 expression) as plasma samples of polytransfused thrombocytopenic patients without HLA antibodies. It can be concluded that neither an activating nor an inhibitory effect of HLA antibodies on platelet function is significant in vivo. The IVBT seems not to be suited for compatibility testing.

Antibodies↗
PubMed1995

The gel test: investigation into the aetiology and the significance of a positive auto-control.

BACKGROUND: Shortly after the gel test was introduced into routine immunohaematology, an increased percentage of patients were reported to show a positive auto-control in the indirect antiglobulin test (IAT) of uncertain significance as the direct antiglobulin test (DAT) in the tube technique was negative. MATERIALS AND METHODS: In our study 13,280 randomized patient blood samples were screened and additional investigations carried out including an analysis of patient histories in the 97 blood samples that were auto-control positive in the gel test. RESULTS: In 87.4%, a re-testing with polyspecific antiglobulin serum (83.2% with anti-IgG) showed positive results in contrast to only 52.9% re-tested by the tube test. Neither nonspecificity nor cold agglutinins were significant. None of the patients examined showed any signs of haemolysis except for one with pernicious anaemia. We concluded that the increased number of positive auto-controls and DATs is due to the greater sensitivity of the gel test and thus the detection of minute quantities of specific cell-bound IgG molecules, i.e. warm auto-antibodies or drug-induced antibodies. CONCLUSION: Prior to transfusion, a positive result should be confirmed by a tube DAT. If this test is negative and there is no history of a previous transfusion or of haemolysis, the transfusion should not be delayed by carrying out further time-consuming investigations.

Adult↗
PubMed1995

[Survey of blood donors on the topic of "reimbursement for blood donors"].

BACKGROUND: Remuneration for blood donors, in the way as presently handled by governmental and communal blood transfusion services in Germany, is not generally accepted. It is feared that donors are recruited with increased risk to transmit infectious diseases, especially AIDS. Alternative incentives are discussed. After the so-called AIDS scandal in Germany, a change in the donor motivation was to be expected, associated with an increased willingness to renounce remuneration. Therefore, we performed the present survey, in which we evaluated the donor's willingness to renounce remuneration, possibilities of cashless remuneration and other alternative incentives. MATERIAL AND METHODS: During March and April 1994, a total of 1,157 blood donors of the University Blood Bank Marburg were questioned anonymously by a questionnaire in the framework of whole-blood donations. Beside the above-mentioned aspects demoscopic data were included (age, sex, profession, journey). RESULTS: Cutting of remuneration without any other compensation was refused by 86.1% of the donors, 77% would not want to further donate blood in this case. Transfer of money to a bank account instead of cash payment was accepted by 78.6%, the use of non-negotiable cheques by 68.7%. Alternative compensation by tickets for theater, concert, cinema or coupons for restaurants met with the approval of only 27.3%; under these circumstances, 36.9% would be willing to continue blood donation. With increasing age and number of donations, but largely independent of social status, donors attached greater importance to retention of remuneration. DISCUSSION: Cutting of remuneration would result in a considerable reduction of the willingness to donate blood within the population of donors of the governmental and communal blood transfusion services. However, an increase of virus safety of the blood products would not be reached in this way, since especially the long-term donors would be driven away. Considerable bottlenecks, particularly in the specific blood supply of hospital-integrated blood transfusion services, would have to be expected.

Adolescent↗
PubMed1995

[Pseudothrombocytopenia: case reports and review of the literature].

BACKGROUND: Pseudothrombocytopenia (PTP) is an in vitro phenomenon with falsely low platelet counts determined automatically. Usually the thrombocytopenia is noticed accidentally without a corresponding tendency to bleeding. If this phenomenon is not recognized, misinterpretation may bring the patient into a considerable risk by diagnostical and therapeutical mistakes. By own cases and analysis of the literature, causes, appearance. incidence, as well as diagnostic and clinical problems of PTP shall be explained in detail. CASUISTICS: We report on three patients who showed a significant decrease of platelet counts after surgery DIC (disseminated intravascular coagulation) and heparin-induced thrombocytopenia type II (white clot syndrome) were assumed primarily. In all three cases the reason for the low postoperative platelet counts was found to he due to PTP caused by cold agglutinins. CONCLUSION: From the cases described it can he concluded that PTP may develop during postoperative clinical course. Due to the broad differential diagnostic spectrum in the postoperative situation. PTP is hardly considered. Therefore, there is a greater chance of misinterpretation and therapeutic mistakes. In case of low platelet counts PTP should always be excluded, even when thrombocytopenia seems to be explicable differently.

Aged↗
PubMed1994

A contribution to the indications for platelet transfusion and determination of its therapeutic efficacy.

The platelet count does not really reflect the true bleeding risk in chronically thrombocytopenic patients. Recently, we reported on two modifications of an in vitro bleeding test (IVBT) which appeared to be suitable for the evaluation of primary non-vascular hemostatis in thrombocytopenic and anemic patients (platelets 10-50,000/microL, hct 16-30 L/L). We report on the clinical study conducted with the IVBT modification which proved to be superior. Fifty thrombocytopenic patients, 42 with bone marrow hypoplasia and 8 with autoimmune thrombocytopenia, were followed up for a total of 686 days and received 161 platelet transfusions (mainly from cell separator). The IVBT was carried out with the Thrombostat 4000 in triplicate using 120 microns filters and evaluating the occlusion time (OT). Additionally, cell count, hematocrit, body temperature, platelet volume, platelet distribution width, Simplate time and a detailed analysis of bleeding signs for the calculation of a bleeding score were performed. The IVBT modification used allowed the determination of platelet-related bleeding risk in thrombocytopenic patients. With the IVBT, significant differences in platelet function in different patients could be demonstrated which primarily reflected the underlying disease. In addition, bone marrow regeneration correlated with platelet function. From the findings of this study, the authors formulate criteria for the indication of platelet transfusion which includes platelet function as well as the platelet count. Increased individual bleeding risk factors have to be considered too. But before generalization these criteria have to be verified by a controlled prospective study.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Coagulation Tests↗
PubMed1994

[A retrospective study of the practice of "look-back" procedures, on the incidence of HIV-1/2-positive blood donors and the risk of transfusion-associated HIV infection in public-community blood banks in Germany].

OBJECTIVE: 'Look-back' investigations can reveal and confirm transfusion-transmitted infectious diseases and provide data for risk calculations of blood transfusions. DESIGN: In 1993 we distributed a questionnaire to all governmental and communal blood transfusion services in Germany. The questionnaire comprised questions about the methods, numbers and results of look-back investigations in case of HIV-1/2-positive blood donors with previous donations and in case of HIV-1/2-positive recipients of blood transfusions. The questionnaire was returned by almost all blood transfusion services (n = 75). One additional institution briefly informed us by telephone. SETTING: All governmental and communal blood transfusion services in Germany. PATIENTS: All recipients of blood or blood products in the years from 1985 till the end of 1992 who were treated in hospitals supplied by the transfusion services defined above. INTERVENTIONS: None. RESULTS: All blood transfusion services included have performed look-back studies since 1985. The methods used varied considerably. The interval of looking back mostly was sufficient. A main problem was the poor documentation in the medical records. The incidence of HIV-1/2-positive blood donations decreased from 11.6/100,000 in 1985 to 3.4/100,000 in 1992. Only 7 of 73 transfusion-transmitted HIV infections derived from transfusions after the introduction of HIV testing (October 1985). Since then the risk of transfusion-transmitted HIV infection can be calculated as 1/800,000 whole-blood donations of governmental and communal blood transfusion services. CONCLUSIONS: Since the introduction of HIV testing the risk of transfusion-transmitted HIV infection in Germany has been very low, at a rather stable rate of 1/800,000. The data from the look-back studies confirm the previous estimations of the risk of transfusion-transmitted HIV infections, which was calculated by the HIV incidence in the donor population. Nevertheless there is a need for standardization of look-back investigations.

AIDS Serodiagnosis↗