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Biomedical subjects

P Didisheim

Publications and source records attributed to P Didisheim.

At least 19 recordsLinked to original sources
PubMed1986

Quantification of regional platelet and calcium deposition on pericardial tissue valve prostheses in calves and effect of hydroxyethylene diphosphonate.

Mitral valves were replaced with 25 mm bovine pericardial tissue valve prostheses (Ionescu-Shiley) in 45 calves (23 controls and 22 treated daily with hydroxyethylene diphosphonate). Before being killed 1, 14, 30, and 90 days later, the calves received In-labeled autologous platelets intravenously. Regional variations in platelet deposition were measured by a new technique. Thrombus was noted early on the flexion zone of the valve; with time it increased on the free edge and central zone. Platelet deposition was initially high on the flexion zone, attachment zone, sewing ring, and perivalvular tissue but decreased with time. Hydroxyethylene diphosphonate treatment tended to decrease platelet deposition in all zones. Calcium content was high in thrombus and increased in all zones with time, in both groups, but the deposition was less in the group treated with hydroxyethylene diphosphonate. Collagenous tissue and adherent thrombus appear to provide nucleation sites for calcification.

Animals↗
PubMed1984

Clinical evaluation of a new test of hemostasis: the Filter Bleeding Time.

The clinical value of a new in vitro test of hemostasis, which we have called Filter Bleeding Time (FBT), was determined in 59 patients referred because of a suspected bleeding disorder. FBT is based on the progressive slowing of the drop rate of citrated blood through a filter of woven Dacron under constant pressure as platelet aggregates occlude the filter. The value for FBT is defined as the time when the blood drop interval has reached 1 minute. The Mayo modification of the Ivy bleeding time (IBT) was performed in all patients; platelet response to ADP, collagen, epinephrine and arachidonate was performed in 24 patients. In 30 normal volunteers FBT measured 1-3 hr after venipuncture was 2.8 +/- 1.5 (means +/- 1SD) min. The FBT was prolonged in 3 of 3 patients with Glanzmann's thrombasthenia, 2 with disseminated intravascular coagulation, 1 with chronic lymphocytic leukemia, 1 with myelofibrosis, and 1 who had taken aspirin. In 6 patients FBT was prolonged while IBT was normal: 4 after taking aspirin, 2 with polycythemia vera. All 6 had reduced platelet aggregation (PA) to ADP (5 microM), collagen (2 mg/ml), epinephrine (5 microM) and/or arachidonate (1.7 mM). In 3 patients FBT was normal while IBT was abnormal: 1 with disseminated intravascular coagulation, 2 undiagnosed; 1 of these 3 had abnormal PA. Of 6 patients with von Willebrand's disease, FBT was prolonged in 5 and borderline in 1; IBT was prolonged in 3, normal in 1, and not done in 2 infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Arachidonic Acids↗
PubMed1984

Platelet deposition on and calcification of bovine pericardial valve.

Platelet deposition on bovine pericardial mitral valves was quantified in healthy adult mongrel dogs at 1, 14 and 30 days post-implantation and 24 h after i.v. injection of 400-500 microCi of autologous 111In-platelets. In vitro quantitation of platelet deposition on components of the prosthesis indicated maximal activity at one day with a successive decrease in activity at 14 and 30 days. At one day, platelet-associated radioactivity on the sewing ring was 3-4 times as great as on the leaflets, but at 14 and 30 days this had dropped to approximately half of the value on the leaflets. Calves underwent mitral valve replacement with a bovine pericardial valve. Thirty days post-operatively, 111Indium labeled labeled platelets were administered i.v.; 24 h later, calves were sacrificed and sections of each valve leaflet were analyzed for platelet and calcium deposition. Platelet deposition per mm2 of surface was greatest at the free edge of the leaflet, followed by the central zone and flexion point. Calves treated with sodium hydroxyethylene diphosphonate (5 mg kg-1 day-1 s.c.) had reduced platelet deposition but no reduced calcium content on the valves after 30 days compared with untreated calves. In flow chamber studies, platelet deposition from the heparinized blood of normal calves was significantly less on the smooth (inner) than on the rough (outer) surface of fixed bovine pericardium.

Animals↗
PubMed1983

Filter bleeding time: a new in vitro test of hemostasis. I. Evaluation in normal and thrombocytopenic subjects.

Disadvantages of current bleeding time methods include poor reproducibility, limited repeatability, and at times scar formation. We report a new, in vitro technique which circumvents these problems. Venous blood is collected in sodium citrate, stored capped in a siliconized tube at 37 degrees C until use, and made to flow under constant pressure through a filter of Woven Dacron. Flow rate progressively falls as platelet aggregates occlude the filter, as verified by scanning electron microscopy and 111Indium-labeled platelet radioactivity of the filter. Filter bleeding time (FBT) was 4.33 +/- 1.79 (means x +/- SD) min in 23 healthy human volunteers and 3.08 +/- 1.08 min in 14 normal dogs. Bleeding volume (BV) (number of drops) was 29 +/- 12 in the humans and 16 +/- 6 in the dogs. Initial bleeding rate (IBR) (number of drops during first minute) was 14 +/- 3 in citrated blood and 25 +/- 5 drops/min in EDTA blood of the humans (P = 9 X 10(-10)), 8 +/- 2 in citrated blood and 14 +/- 6 drops/min in EDTA blood of the dogs (P = .0004). Percent platelet reduction during passage of blood through the filter (PCR) was 27.5 +/- 7.2 in citrated blood and 4.9 +/- 2.6 in EDTA blood of the humans (P = 2 X 10(-12)), while in dogs it was 25.7 +/- 8.3 in citrated blood and 5.3 +/- 4.2 in EDTA blood (P = 8 X 10(-7)). The results of these parameters using human platelet rich plasmas (PRPs) were similar to those with human whole blood, but significant decrease of drop rate was not observed in canine PRPs during passage of PRP through the filter. FBT, BV, and IBR were correlated (r = -0.91, -0.84 and -0.62 respectively) with platelet count in 12 specimens obtained from 4 dogs in which thrombocytopenia (107 to 4 X 10(3) platelets/microliter) was induced by estradiol. This new test is unaffected by specimen transport by pneumatic tube, is sensitive to platelets, and should be useful for analysis of both quantitative and qualitative platelet abnormalities in man.

Animals↗
PubMed1982

Indium-111 tropolone, a new tracer for platelet labeling.

Platelets have been labeled with a new neutral, lipid-soluble metal complex of indium 111 (111In) and tropolone. Unlike oxine, which is soluble in ethyl alcohol, tropolone is soluble in isotonic saline. Platelet labeling with 111In tropolone can be performed in both acid-citrate-dextrose (ACD) plasma and ACD saline within two hours. Labeling efficiency has been 80% to 90%. 111In tropolone in ACD saline and ACD plasma at tropolone concentrations of 5 and 10 micrograms/ml, respectively, and incubation of the platelets with the tracer at room temperature for 20 minutes were optimal conditions for labeling. The authors have developed an ACD-saline kit for convenient preparation of 111In-labeled platelets. No adverse effect of 111In tropolone on platelets has been observed in studies of biodistribution, recovery, and survival of platelets in rabbits and dogs.

Animals↗
PubMed1981

Indium-111 tropolone, a new high-affinity platelet label: preparation and evaluation of labeling parameters.

Platelets were isolated with a new neutral, lipid-soluble metal complex of indium-111 and tropolone. Unlike oxine, which must be dissolved in ethyl alcohol, tropolone is soluble saline. Platelet labeling with In-111 tropolone can be performed in both acid-citrate-dextrose (ACD)-plasma and ACD-saline media within two hours' time. Labeling efficiency has been 80-90% in ACD-saline and 60-70% in the ACD-plasma medium. Optimum concentrations for the labeling of platelets with In-111 tropolone were 5 micrograms/ml in ACD-saline and 10 micrograms/ml in ACD-plasma, using a 15-min incubation at room temperature. A kit formulation for convenient routine preparation of In-111-labeled platelets has been developed. Seven parameters of platelet labeling were studied: concentration of tropolone, citrate, plasma proteins, and calcium ions; also platelet density, temperature, and pH of incubation medium. Their effects on the mechanism of platelet labeling with lipid-soluble tracers are discussed.

Affinity Labels↗
PubMed1980

Two new artifacts in automated coagulation testing.

Two artifacts were noted during the routine use of the Sherwood Lancer Coagulyzer. The first was that prothrombin times for 44 patients were greater than 90 sec on the Sherwood instrument, but were significantly shorter using reference methods. All 44 patients had subnormal fibrinogen values. Continuous optical density tracings during clotting performed for 11 patients demonstrated low slopes and amplitudes. For the three patients tested, the addition of fibrinogen corrected prothrombin times to values similar to those obtained on the Bio-Data instrument. Twenty-four of the patients subsequently died, 20 within three weeks of the observation of the artifact. The second artifact was that activated partial thromboplastin times for 12 patients were 9 sec on the Sherwood instrument, but were either normal or prolonged when using reference methods. Continuous tracings performed for nine patients demonstrated early optical density increases before clotting, which were responsible for the spurious values. Eleven of the 12 patients were hypoalbuminemic, and nine of the ten tested had elevated IgM levels. For seven patients, the artifact disappeared with in-vitro correction of hypoalbuminemia. Far from being weaknesses of the Coagulyzer, these artifacts may lead to the discovery of unsuspected, clinically significant laboratory information.

Blood Coagulation Tests↗
PubMed1979

Ultrastructural characteristics of dog and human platelets adherent to native and collagen-coupled cuprophan.

Adhesion of human and dog platelets to native and collagen-coupled Cuprophan under defined flow conditions was studied by scanning and transmission electron microscopy. Dog platelets, singly adherent to and uniformly distributed on both native and collagen-coupled Cuprophan, extend slender pseudopods across the surface without evidence of degranulation. Human platelets, while not adhering to native Cuprophan, formed irregularly shaped, semi-confluent cytoplasmic sheets on the collagen-coupled surface. Extensive cytoplasmic reorganization and degranulation suggests a post-release state of the human platelets. Aspirin had no apparent effect on either human or dog platelet adhesion or upon the apparent release state of the human platelets.

Adsorption↗
PubMed1978

A comparison of five manually operated coagulation instruments.

The results of activated partial thromboplastin time (APTT) and prothrombin time (PT) determinations on the single-channel Coag-a-Mate, Coagulyzer Jr., Clotek, Electra 650, and Fibrometer instruments were compared with regard to precision, day-to-day reproducibility of results, and accuracy. There was no significant difference among the machines when PT was analyzed. In the APTT study, the single-channel Coag-a-Mate had the best overall precision (coefficient of variation 2 to 4%), while the Coag-a-Mate and the Electra 650 had the best day-to-day reproducibility (coefficient of variation 2 to 5%). The comparison study indicated good correlation (r greater than or equal to 0.95) between the reference instrument (Bio/Data CA-15) and the single-channel Coag-a-Mate, Electra 650, and Clotek. The correlation for the Coagulyzer Jr. was also quite good (r = 0.95), but it could not detect some of the clots detected by the other machines. The Fibrometer showed significantly poorer correlation (r = 0.87) when compared with the other instruments.

Automation↗
PubMed1978

An evaluation of four automated coagulation instruments.

Four automated coagulation instruments were evaluated for performance of prothrombin time and activated partial thromboplastin time (APTT): the Dade Auto-Fi, General Diagnostics Dual Channel Coag-a-Mate, MLA Electra 600D, and Sherwood Lancer Coagulyzer. Statistical comparisons showed only minor differences among values determined with these instruments. Reproducibilities of duplicate prothrombin times and APTTs were equivalent on all machines except the Coag-a-Mate; the problem here was in the alignment of the two channels, and should be correctable. Differences exist in the costs, technician acceptance, computer interfacing, and normal values on these instruments. The MLA instrument has the lowest purchase price, followed by the Sherwood and then the General Diagnostics instruments. These three instruments have comparable costs for disposable supplies. The Dade has a substantially higher purchase price and higher costs of disposable supplies. The Sherwood and MLA had the best technician acceptance. All instruments except the Coag-a-Mate can be easily interfaced to a computer. The Dade instrument gave longer coagulation times than the other three instruments when General Diagnostics reagents were used.

Autoanalysis↗