Biomedical subjects

R Mischke

Publications and source records attributed to R Mischke.

At least 91 records · Page 5Linked to original sources

PubMed1995

[Applicability of activated partial thromboplastin time (APTT) as a screening test of milk to medium deficiencies of coagulation factors in cats].

The present investigation examined if the aPTT shows sufficient sensitivity for single factor activities also in cats when measured with the test optimized for humans using a commercial reagent. Comparative measurements were done with different modifications of the aPTT (sample predilution, addition of fibrinogen). Measurements of the aPTT using different methods and the activity of the coagulation factors II, V, X, VIII, IX, XI, and XII were performed in 42 healthy cats in order to determine the reference ranges. The same measurements were done on 21 cat plasmas where at least one of the coagulation factors was diminished in relation to the corresponding reference range. The conventional aPTT reflected the decrease in coagulation factor activity in each of the 21 plasmas by prolongation above the reference range (14.6-24.4 s). The test thus possesses high sensitivity and is a suitable screening test also for the cat. In contrast, in tests with sample predilution the sensitivity was lower (3-4 false negative results). This was probably caused by the distinct increase of the range of the reference values.

Animals↗

PubMed1995

[Automatic cell counting in cat blood].

The usability of the haematology analyzers ¿F-800¿ and ¿System 9000+¿ was investigated in cats using 40 blood samples. Reference measurements were done with a haemocytometer or the microhaematocrit method. Reliable leukocyte counts were measured with the analyzer F-800 in cases only, when the histogram rendered possible a clear demarcation of the leukocyte curve (r=0.97, n=25). With the analyzer System 9000+ a changed basic adjustment of the inferior discriminator (49 fl) vouched for a close correlation with the values measured visually (r=0.94). The volume distribution curves of the erythrocytes and thrombocytes which were partly overlapping allowed an approximate counting of the thrombocytes with both analyzers only of one half of the samples. The inaccuracy resulting from the inexact separation had only a relatively unimportant effect on the automatically measured erythrocyte count due to the numerical relation of erythro- and thrombocytes. Here at a close correlation to the haemocytometer method (r=0.95) was found as well as slightly higher values with the automatic counting. The haematocrit measured with the analyzer F-800 and to a smaller extent by the use of the System 9000+ lay distinctly higher in relation to the values measured by microhaematocrit, when the analyzers were calibrated with human standards. Besides a species specific calibration of the haematocrit and a particular basic adjustment for leukocyte counting with the analyzer System 9000+, the use of the investigated haematology analyzers on feline blood requires an individual estimation of the histograms and removing of the discriminators as well as frequently a repetition of the leukocyte- and thrombocyte counting with a haemocytometer.

Animals↗

PubMed1994

A study on the efficacy of a phospholipid solution in dogs with aspirin-induced thrombocytopathy.

The aim of the present study was to test the haemostyptic properties of a phospholipid complex with platelet factor-3 (PF-3) activity in platelet-dependent haemostatic disorders. The substance was investigated in an animal model comprising six investigational groups (five dogs each). A thrombocytopathy was created in the dogs belonging to groups 1-5 by intravenous administration of 20 mg/kg body weight (BW) acetylsalicylic acid (ASA). Two hours later a human albumin solution (5%) (control group) or a phospholipid complex with PF-3 activity was injected or infused intravenously in different dosages. In dogs pre-treated with ASA, injection of 2 ml/kg BW of the phospholipid complex shortened capillary bleeding time, which was prolonged as a consequence of ASA-treatment. This effect lasted for 4 h at least. The capability of the platelets to aggregate increased 5 min after intravenous injection of the phospholipid without differences in the respective groups. At the same time platelet counts dropped to approximately 50%, but increased again distinctly after 30 min. When the phospholipid complex was administered to clinically healthy dogs who had not been treated with ASA, this resulted in prolongation of the capillary bleeding time as well as a significant platelet drop in the peripheral blood. Although these were only short-term effects after administration of the phospholipid complex, a disadvantageous effect cannot be excluded in patients suffering from haemorrhagic diathesis. For this reason, a phospholipid complex with PF-3 activity cannot be recommended as a therapeutic agent for platelet-dependent coagulation disorders in the dog.

Animals↗

PubMed1994

[Measuring fibrinogen concentrations in healthy dogs: standardization, comparison of methods and reference values].

Plasma fibrinogen concentration was measured in 67 healthy, adult dogs using five different methods (gravimetry, methods described by JACOBSSON (1955) RATNOFF and MENZIE (1951), and CLAUSS (1957), and functional photometric assay). Apart from using linear regression and the Pearson correlation coefficient (r) in order to characterize the relation between different methods, reference ranges (2.5-97.5%-fractile) were calculated for all methods. For calibration of the CLAUSS method (1957) and the photometric assay, dog plasma with a defined fibrinogen concentration was used. Measurements of commercial human fibrinogen standards yielded a good conformity with the concentrations specified by the manufacturer (values approximately 3% too low). These standards appear, therefore, to be also suited to the calibration of measurements of dog fibrinogen. The reference range for the gravimetry was 1.08-2.88 g fibrinogen per litre of plasma. A considerable conformity and close correlation was seen between the fibrinogen concentration measured by gravimetry and by using methods described by JACOBSSON (1955; y = 1.088 x -0.142, r = 0.967) or CLAUSS (1957; y = 0.999 x -0.004, r = 0.973), respectively. Between the reference-method gravimetry and the photometric method and RATNOFF-MENZIE (1951) method, respectively, a less close correlation, as well as a minor conformity, was found.

Animals↗

PubMed1994

[Methodological aspects for the determination of the coagulative activity of coagulation factors II, V, VII and X from dog plasma].

For optimization of single factor II, V, VII and X activity measurements in dogs, dilution series of dog pool plasma were prepared using different commercially available calcium thromboplastins and deficient plasmas. Measured by use of a canine reference curve, the single factor activity in humans was 89% (factor II), 13% (factor V), 27% (factor VII) and 84% (factor X). Because the factor V and VII activity in dogs is much higher than in humans, in measurements using human-deficient plasma, a high sample predilution of at least 1:40 seems to be of advantage. Otherwise extreme variations of the factor V and VII activity may also influence the results of the other single factors. For determination of factor II, V and X activity, therefore, a non-standardized human placenta thromboplastin was especially suitable. With this reagent, the results were also reproducible at high sample dilutions (1:80, factor II and X; 1:160, factor V). Because of the low sensitivity of non-standardized human placenta thromboplastin to factor VII, measurements of this factor at a sample dilution of 1:40 required a standardized human placenta, or rabbit brain thromboplastin had to be used. For factor II measurements, the selection of a suitable deficient plasma is particularly important. Here, the reference curve showed a clear dependence on the commercial preparation chosen.

Animals↗

PubMed1994

[Optimized methods for measuring coagulation factors II, IV, VII and X in cats].

Since the single factor activity of the cat differed in part distinctly from humans (factor II: 94%, factor V: 500%, factor VII: 125%, factor X: 62%) the method had to be optimized, above all to exclude an influence of a reactive increased factor V-activity on the results of the other coagulation factors. Dilution series of cat pool plasma (CPP) (n = 50 cats) showed, that a commercial human placenta thromboplastin was more suitable as activating reagent than rabbit brain thromboplastin. Using the required sample predilution (1:40), measurements with the latter reagent were more precise when measured on the relation between the imprecision and the time interval between different CPP-dilution steps. Reference curves were prepared for CPP using the optimized method and human placenta thromboplastin (50 microliters 1:40 prediluted sample and 50 microliters deficient plasma were incubated at 37 degrees C for 1 minute, addition of 200 microliters Ca-thromboplastin) and reference ranges were calculated using the values of 57 cats (factor II: 74-126%, factor V: 42-184%, factor VII 56-150%, factor X: 65-143%).

Animals↗

PubMed1994

[Activity of coagulation factors II, V, VII and X in healthy dogs--dependence on age, sex and breed].

The activity of the coagulation factors II, V, VII and X was measured in plasmas of 167 healthy dogs of different age, sex and breeds using a test optimized for dogs. During the first months of life particularly the factor X-activity, but also the activity of factor-II-, and by way of suggestion the factor V-activity was lower in comparison to adult dogs. A dependence on the sex was only seen for the factor II- (p = 0.0497) and V-activity (p = 0.0467), which was slightly higher in not castrated female than in male dogs. Significant differences between different breeds existed for factor VII. With regard to a collective of different breeds the reference values (2.5- and 97.5%-quantile) were calculated for adult dogs (n = 111). Especially the range of the factor VII- (62-180%), and also of factor V-activity (68-137%) was wider than that of the factor II- (84-126%) and factor X-activity (77-121%).

Aging↗

PubMed1993

[The effect of factor VIII:C activity on the activated partial thromboplastin time (aPTT) in the dog. Adaptation of the aPTT as a screening test for canine hemophilia A?].

The factor VIII:C-sensitivity of the aPTT in dogs was investigated for 2 different, commercially available reagents. For this purpose, 45 plasmas with a decreased factor VIII:C-activity, which were collected from haemophilic dogs (n = 10) at variable points of time of a substitution therapy were used. Moreover, by the stepwise addition of a canine factor VIII:C-deficient plasma to a reference pool plasma it was examined whether factor VIII:C-sensitivity could be increased by prediluting the plasma. By use of both reagents all 45 pathological plasmas (factor VIII:C-activity: 1.5-58%, reference values: 63-144%) showed a prolonged aPTT in relation to the respective reference values. The aPTT correlated well with a pathologically decreased factor VIII:C-activity. In conclusion, the aPTT measured with commercially available reagents according to the manufacturers' instruction is a well suited screening test for haemophilia A and monitoring of its therapy in dogs. Predilution of the dog plasma used in the test does not lead to a distinct of the sensitivity. On the contrary, a high dilution leads to a decrease of sensitivity.

Animals↗

PubMed1992

[Laboratory diagnosis and differential diagnosis of disseminated intravascular coagulation in the dog].

The laboratory diagnostic possibilities for characterization of disseminated intravascular coagulation (DIC) in dogs are reviewed. A DIC can be demonstrated by means of: 1. Simultaneous consumption of platelets, fibrinogen, coagulation factors and inhibitors of coagulation 2. Increased plasma levels of the specific reaction products fibrin monomers and fibrinopeptides 3. Secondary hyperfibrinolysis, especially an increase in plasma concentrations of fibrin(ogen) degradation products 4. Presence of schistocytes in the blood smear 5. Improvement in the coagulation values during an efficacious anticoagulant therapy 6. Indication of enhanced turnover and formation of microthrombi in different organs by radioisotopically detected coagulation components. Different principles of the laboratory diagnostic procedure in DIC are illustrated by the results of an animal experiment and clinical case reports. Concerning differential diagnosis among other things a deprivation- and dilution effect as well as a disturbance of synthesis have to be considered. One must especially bear in mind that a DIC may also be caused by different coagulator disturbances, e.g. of prothrombin complex synthesis. A DIC can mask such a defect in laboratory diagnostic findings, thereby complicating the diagnosis.

Animals↗

PubMed1991

[Modification of the global coagulation tests for the dog. Significance for the monitoring of heparin therapy].

When the global coagulation tests Quick's test, aPTT and thrombin time are carried out on dogs using reagents from the human medical sector according to the manufacturer's instructions, they react insensitively to deficiencies of the corresponding coagulation factors or to the presence of fibrin degradation products. In the present study it was attempted to develop sensitive global tests for the dog by modifying these tests. The Quick's test reacted apparently more sensitively after a 1:4 dilution of the test plasma with physiological saline solution. The sensitivity of the aPTT was demonstrated by the addition of BaSO4-adsorbed plasma to normal plasma. It seems to be particularly advantageous to combine a 1:3 plasma dilution with a reduction in the CaCl2-concentration to 5 mmol/l. Likewise, plasma dilution allows the thrombin time to react more sensitively in the presence of increased concentrations of fibrin degradation products. The aPTT and thrombin time are, as in human beings, suited for the control of a heparin therapy. However, since prolongation of the coagulation times is considerably dependent on the test chosen, the heparin sensitivity of the test should be determined in vitro prior to use.

Animals↗

PubMedDate not supplied

Influence of fibrinogen degradation products on thrombin time, activated partial thromboplastin time and prothrombin time of canine plasma.

To investigate how thrombin time, activated partial thromboplastin time (APTT) and prothrombin time are influenced by fibrinogen degradation products (FDP), different concentrations (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8 and 1.0 mg/ml) of the purified FDP X, Y, D and E were added to the plasma of healthy dogs. If fragment Y was added to the plasma a considerable inhibitory effect could be demonstrated for all three test systems. A significant prolongation (p < 0.05) was found for concentrations of > or =0.1 mg/ml (thrombin time, APTT) and > or =0.2 mg/ml (prothrombin time). With FDP Y concentrations from >0.185 mg/ml (prothrombin time) to >0.24 mg/ml (APTT) coagulation time was prolonged beyond the respective reference range. As regards the other fragments, a comparable inhibitory effect could only be shown for fragment X added to the thrombin time test system. This effect can most probably be explained by the competition of the FDP X and fibrinogen for the fibrinogen binding sites of thrombin, rather than by a fibrin polymerization disorder. The results demonstrate that for plasma with normal fibrinogen concentration the group tests are only prolonged beyond the reference range at FDP concentrations very rarely found in spontaneous hyperfibrinolysis.

Animals↗

PubMedDate not supplied

Comparison of different methods to measure fibrinogen concentration in canine plasma with respect to their sensitivity towards the fibrinogen degradation products X, Y and D.

In this study, fibrinogen measurements according to the Clauss method, photometric method and Jacobsson method have been investigated to find out how they are influenced by adding in vitro the purified canine fibrinogen degradation products (FDP) X, Y and D. Test results according to the Clauss method were found to be underestimated if the fragments X, Y and D were added while measurements according to the Jacobsson method turned out to underestimate the real fibrinogen concentration if the FDP Y and D were added. The Clauss method was particularly sensitive towards FDP. Results were considerably underestimated even with a quantity as little as 0.05 g FDP Y or FDP D/g fibrinogen (p < 0.05). The photometric method was only affected by FDP X leading to false high results. If FDP X was added, fibrinogen values were also overestimated with the Jacobsson method. Our results demonstrate that the photometric method is the most accurate.

Animals↗

PubMedDate not supplied

Alterations of the global haemostatic function test 'resonance thrombography' in spontaneously traumatised dogs.

Samples taken from 30 dogs with spontaneously acute trauma were investigated with two different resonance thrombographs (instrument 2: 28 dogs), a global method for examination of the haemostatic system. Reaction time of the resonance thrombogram (RTG-r), fibrin generation time (RTG-f), fibrin amplitude (RTG-F) and parameters of platelet function [amplitude of the platelet leg (RTG-P) and descending time of the platelet leg (RTG-p)] were evaluated statistically and compared with a normal control as well as with the results of individual components of the haemostatic system and other screening tests. Comparison of the results of the RTG of dogs suffering from trauma with the normal control revealed differences only for RTG-r, which was longer when measured with instrument 1 and lower RTG-F values measured with both instruments. Depending on the RTG parameter and instrument, only 1-6 samples showed values outside the reference ranges. Only 4 out of 26 cases (resonance thrombograph 2: 2 out of 24 cases) with mild to moderate deficiency in individual coagulation factor activity showed a prolongation of RTG-r which was significantly less sensitive than activated partial thromboplastin time (p < 0.001). Of the 26 samples having mainly mildly to moderately increased fibrin(ogen) degradation product (FDP) levels (median: 39 microg/ml, range: 2-90 microg/ml, reference values: <18 microg/ml) only between 1 and 5 showed abnormalities of the parameters RTG-f and/or RTG-F. The results of this study show in particular the limited sensitivity of the method for detecting individual coagulation factor deficiencies and minimal to moderate increases of FDP concentrations. Remarkable alterations of fibrin generation as measured by the resonance thrombograph are a rare condition in dogs with acute accidental trauma.

Accidents, Traffic↗

PubMedDate not supplied

[Long-term EKG in dogs: comparison between a computerized system and visual arrhythmia analysis].

Based on results of holter ecg recordings taken from 38 dogs the computerized analyses system turned out as method not exactly valuing the frequency and sensitivity of arrhythmias. Despite there was a significant correlation between the computerized and visual arrhythmia analysis for ventricular respectively supraventricular premature beats, in individual cases there was an important aberration between the particular values.

Animals↗

PubMedDate not supplied

[Changes in platelet concentrates from dogs due to storage. I. Platelet count in in vitro function].

The possibility of storage of canine platelet concentrates (PC) was investigated using PC from dogs which were obtained with an automatic cell separator in C4-cell separation sets with low gasdiffusionable Polyvinylchlorid (PVC) storage containers or in C4L-sets developed for storage with high gasdiffusionable Polyolefin (PO) containers, respectively. The storage was carried out for a period of 10 days under permanent agitation at 22 degrees C (C4/22 degrees C, n = 10; C4L/22 degrees C, n = 11) or at 4 degrees C (C4L/4 degrees C, n = 6), respectively. Measurements were done directly after production of the PC, after 6 hours and then daily during the 10-day storage period. In the first part of this paper the results of platelet count (determined automatically with a blood cell differentiation automat and visually), the number of platelet aggregates, the mean platelet volume (MPV) as well as the platelet function with regard to the platelet aggregation induced by collagen or ADP and the resonance-thrombogram (RTG) are presented. The platelet count, measured automatically as well as visually, remained preponderantly constant over the complete storage time in all storage conditions. Dependent on the storage conditions--especially under storage at 22 degrees C--an increase of the number of platelet aggregates and a decrease of MPV was determined. In addition, the loss of platelet function measured by aggregation induced by collagen as well as by ADP showed a significant dependency of storage conditions. The stored platelets lost their ability to aggregate under C4/22 degrees C-conditions after a storage period of 2 days, under C4L/22 degrees C-conditions after 4 days and under C4L/4 degrees C-conditions not before 8 days of storage. Previous resuspending of platelets in fresh plasma delayed the loss of platelet function. Because the loss of platelet function described in the RTG became significant at nearly the same point in time, a storage of canine PC under corresponding conditions can be recommended for upto 2 days (C4/22 degrees C), for 4 days (C4L/22 degrees C) or 8-10 days (C4L/4 degrees C), respectively.

Adenosine Diphosphate↗

PubMedDate not supplied

[Comparison of factor VIII:C and factor IX sensitivity of different commercial APTT reagents for canine plasma].

In the present study, six commercial reagents for the determination of the activated partial thromboplastin time (APTT) were compared with respect to their factor VIII:C and factor IX sensitivity for measurements of canine plasma. For this purpose, plasma with different levels of factor VIII:C or factor XI activity (100, 80, 70, 60, 50, 40, 30, 20, 15, and 10% [factor VIII:C: additionally 5%]) was prepared by mixing pool plasma with plasma of dogs with haemophilia A or B. Double measurements of three different sample mixtures were carried out for each activity level. The sensitivity of the reagents was measured first based on the ratios of the coagulation time to the 100% values. In addition, the single factor activity (F VIII:C/IX(X0.975)), whose accompanying APTT corresponded to the upper limit of the reference range (97.5%-quantile, n = 50) of the respective reagent, was determined graphically. The APTT reflected a decrease of factor IX activity generally more sensitive than a reduction of factor IX activity of an identical degree. Based on ratios distant differences respecting factor VIII:C and factor IX sensitivity were found between different reagents using two way analysis of variance (p < 0.05). Significant differences between various reagents were also found with respect to the F VIII:C(X0.975) and the F IX(X0.975). These corresponded to values between 27 and 50% or 32 and 64%, respectively, dependent on the reagent. As a result, the more sensitive reagents fulfilled the demands on the sensitivity of APTT in humans. Based on the latter criterion the highest sensitivity for both factors was found for the same reagent (Pathromtin) consisting of kaolin as a contact activator and human placental phospholipid. Respecting all proofed reagents, however, no relation was found between contact activator and single factor sensitivity.

Animals↗

PubMedDate not supplied

[Reference values of the red blood profile in beagle, German shepherd and golden retriever puppies].

In the present study, blood samples were taken from clinically healthy puppies of the breeds Beagle, German Shepherd, and Golden Retriever between days 1 and 3 (n = 146), 8 and 10 (n = 137), 28 and 33 (n = 151), and 50 and 58 (n = 129) post natum. Measurements for red blood cell count, haemoglobin concentration, haematocrit, mean erythrocyte volume (MCV), mean corpuscular haemoglobin (MCH), and mean corpuscular haemoglobin concentration (MCHC) were performed by a semi-automatic blood cell counter; the normoblast number was counted visually. Between the 1st and 3rd day of life, the erythrocyte number of the puppies was 4.57 +/- 0.68 10(6)/microliter and, as such, was clearly below the reference range for adult animals. It further decreased by the 2nd measurement (8th to 10th day of life) to 3.59 +/- 0.41 10(6)/microliter, and then increased again to 4.75 +/- 0.68 10(6)/microliter (reference range: 3.73-6.25 10(6)/microliter, 2.5% to 97.5% percentile) by the final measurement (50th to 58th day of life). The measurement values of the haemoglobin concentration (13.5 +/- 2.0 g/dl) and haematocrit (41.0 +/- 6.5%) after birth were only insignificantly below or around the lower limit of the reference range for adult animals. Both parameters decreased to a more pronounced extent than did the erythrocyte count. They reached a minimum of 8.4 +/- 1.0 g/dl and 26.8 +/- 3.2%, respectively, between the 28th and 33rd day of life. Even at the end of the examination period (50th to 58th day of life), the values of these parameters (10.1 +/- 1.1 g/dl, reference range: 7.5-11.8 g/dl; 32.1 +/- 4.2%, reference range: 24.8 to 40.8%) were remarkably lower than the minimum of reference range for adult dogs. At the 1st sampling (between 1st and 3rd day of life), MCV (89.8 +/- 6.7 fl) and MCH (29.6 +/- 1.9 pg) were distinctly higher than the reference values for adult dogs. Both parameters decreased with increasing age. Thus, from the 50th-58th day of life, the results were comparable to those of adults. No considerable age dependence was found for MCHC. During the first days of life a relatively high number of normoblasts (8 +/- 7/100 Leukozyten) was found; it decreased rapidly. The study revealed significant differences between the breeds, e.g. German Shepherd dogs had lower initial values of erythrocyte count, haemoglobin concentration, and haematocrit when compared to the other breeds. Puppies of this breed also had higher normoblast numbers than the Beagle and Golden Retriever puppies at the 2nd and 3rd samplings. No clear sex differences in the studied parameters were observed. The results of this study reflect the replacement of fetal erythrocytes by postnatal erythrocytes. Moreover, they illustrate the need to use age as well as breed-specific reference ranges.

Aging↗

PubMedDate not supplied

[Sensitivity of resonance thrombograms in thrombocytopenia of dogs].

Based on results of 84 blood samples, taken from 28 dogs suffering from thrombocytopenia, the resonance thrombography turned out as a method with low sensitivity (S) to detect thrombocytopenia in dogs. It was insignificant which one of the two tested resonance thrombographs was taken for measurement and which parameter of the resonance thrombogram (RTG) was used for the thrombocytic potential of haemostasis, the amplitude (RTG-P) or descending time of the platelet side. Only samples containing < or = 25,000 platelets/microliter were reliably measured (S > or = 0.90), whereas thrombocytopenias with > 50,000 platelets/microliter usually resulted in false negative results. The correlation between the platelet count and RTG-P could be almost expressed by a geometrical regression (rs = -0.709). The low sensitivity of RTG mirrors the multifactorial influences and contrasts to the exclusive use of RTG in the screening of thrombocytopenia.

Animals↗