Electron Microscopy of Human Platelet Aggregates Formed in vitro with and without Fibrin Production

1970 ◽  
Vol 7 (2) ◽  
pp. 84-103
Author(s):  
B.A. Warren ◽  
M.G. Davey
Keyword(s):  
Electron Microscopy ◽  
Human Platelet ◽  
Platelet Aggregates

Endothelial Alterations During The Platelet Activating Factor (PAF) Respiratory Distress Syndrome

1981 ◽  
Author(s):  
J C Lewis ◽  
J T O’Flaherty ◽  
C M McCall ◽  
R L Wykle
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Platelet Activating Factor ◽  
Capillary Endothelium ◽  
Cytotoxic Action ◽  
High Concentration ◽  
Rabbit Lung ◽  
Capillary Endothelial Cells ◽  
Platelet Aggregates

PAF (l-0-alkyl-2-0-acetyl-sn-gylcero-3-phosphocholine) induces polymorphonucelar leukocyte and platelet stasis in rabbit lung capillaries in vitro and produces a model of acute respiratory disease. Since PAF mediates anaphylactic reactions, a study was done to determine the ultrastructural effects of PAF treatment. Mature rabbits were treated by intravenous administration of either PAF (0.15-10 μg/kg: 8 animals) or BSA (the PAF carrier: 3 animals) prior to sacrifice and intraventricular perfusion with 0.1 M phosphate buffered (pH 7.2) glutaraldehyde (2.5%). Animals (n=5) injected with a high concentration of PAF (3-10 μg/kg) and sacrificed within 15 minutes of PAF administration had grossly contracted lungs, the vasculature of which (as observed by scanning electron microscopy) contained numerous marginated leukocytes and platelet aggregates. Animals (n=3) given PAF in the concentration range 0.15-2.4 μg/kg had less consistent lung contraction and fewer platelet aggregates within capillaries. Luminal surfaces of capillary endothelial cells in all PAF treated animals (when observed by transmission electron microscopy [TEM]) were dramatically altered. In contrast to the uniformly smooth surfaces in control animals, vessels in the PAF treated animals had tortuous surfaces with plasma membrane discontinuities and protrusion of plasma membrane fragments into the capillary lumen. Morphometric analysis of TEM micrographs substantiated statistically significant (p<0.01) increases in the number and size of plasmalemmal vesicles.These observations clearly document a cytotoxic effect for capillary endothelium. This cytotoxic action may in part explain the clinical effect of PAF.

In Vitro Inhibition of Platelet Aggregatton by the Gelatin Plasma Expander Haemaccel.(R)

1979 ◽  
Author(s):  
I. Stibbie ◽  
P.M. van der Plas ◽  
G.L. Ong ◽  
D.S. de Jong ◽  
E. Krenning-Douma ◽  
...  
Keyword(s):  
Heart Surgery ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Open Heart Surgery ◽  
Open Heart ◽  
Specific Mechanism ◽  
Plasma Expander ◽  
Platelet Aggregates ◽  
In Vitro Inhibition

In a study concerning open-heart surgery we found that, platelet aggregates present in heparinised human blood disappeared immediately after addition of the gelatin plasma expander haemaccel. A study was therefore initiated of the effect of haemaccei on platelet appregation (Payton apprepometer, 4W RPM as controlled by stroboscope, 37°C, final platelet count 200-300 χ 109/1) and compared with the effect of bovine serum albumin (USA) and platelet poor plasma (PPP). Haemaccel powder was kindly supplied by Rehringwerke and contained 0.98% sodium, 0.015% calcium and no measurable potassium. 0.3 ml human platelet rich plasma (PRP) was nixed with 0.2 ml haemaccel (final concentrations 0-20 mg/ml) in Tyrode’s solution (2 mM Ca++. pH 7,4), Haemaccel inhibited apgrepation in both citrated and heparinised PRP induced by collagen, ADP or adrenalin, both in the presence or absence of indomethacin (90/μM), PPP (0.2 ml) and BSA (in Tyrode’s solution, final concentrations 0-16 mp/ml) were also inhihitinp, hut on a weipht hasis less than haemaccel. Different Ca++ concentrations in the Tyrode’s solution did not alter the inhibition by haemaccel. Final pH in aggregation mixtures varied by less than 0.10 for a given experiment. It is concluded that, under the conditions used, haemaccel and USA inhibit platelet appregation, probably by a non-specific mechanism.

scholarly journals Human platelet myosin. II. In vitro assembly and structure of myosin filaments.

1975 ◽  
Vol 67 (1) ◽  
pp. 72-92 ◽  
Author(s):  
R Niederman ◽  
T D Pollard
Keyword(s):  
Electron Microscopy ◽  
Ionic Strength ◽  
Thin Section ◽  
Human Platelet ◽  
Myosin Ii ◽  
Myosin Molecule ◽  
Myosin Filaments ◽  
In Vitro Assembly ◽  
Myosin Rod

We have used electron microscopy and solubility measurements to investigate the assembly and structure of purified human platelet myosin and myosin rod into filaments. In buffers with ionic strengths of less than 0.3 M, platelet myosin forms filaments which are remarkable for their small size, being only 320 nm long and 10-11 nm wide in the center of the bare zone. The dimensions of these filaments are not affected greatly by variation of the pH between 7 and 8, variation of the ionic strength between 0.05 and 0.2 M, the presence or absence of 1 mM Mg++ or ATP, or variation of the myosin concentration between 0.05 and 0.7 mg/ml. In 1 mM Ca++ and at pH 6.5 the filaments grow slightly larger. More than 90% of purified platelet myosin molecules assemble into filaments in 0.1 M KC1 at pH 7. Purified preparations of the tail fragment of platelet myosin also form filaments. These filaments are slightly larger than myosin filaments formed under the same conditions, indicating that the size of the myosin filaments may be influenced by some interaction between the head and tail portions of myosin molecules. Calculations based on the size and shape of the myosin filaments, the dimensions of the myosin molecule and analysis of the bare zone reveal that the synthetic platelet myosin filaments consists of 28 myosin molecules arranged in a bipolar array with the heads of two myosin molecules projecting from the backbone of the filament at 14-15 nm intervals. The heads appear to be loosely attached to the backbone by a flexible portion of the myosin tail. Given the concentration of myosin in platelets and the number of myosin molecules per filament, very few of these thin myosin filaments should be present in a thin section of a platelet, even if all of the myosin molecules are aggregated into filaments.

Aggregation of Rabbit Blood Platelets Produced in Vitro by Saline “Extract” of Tendons

1963 ◽  
Vol 09 (02) ◽  
pp. 248-263 ◽  
Author(s):  
Torstein Hovig
Keyword(s):  
Electron Microscopy ◽  
Blood Coagulation ◽  
Platelet Rich Plasma ◽  
Blood Platelets ◽  
Adenosine Diphosphate ◽  
Blood Platelet ◽  
Saline Extract ◽  
Rabbit Blood ◽  
Platelet Aggregates

SummaryRabbit blood platelet aggregates were produced in vitro by addition of rabbit tendon “extract” to citrated platelet-rich plasma. The aggregating activity was not due to presence of adenosine diphosphate in the “extracts” and was unrelated to blood coagulation. The aggregating principle was destroyed by heating of the “extract” to 60° C for 15 minutes or by incubation with collagenase for 1 hour at 37° C. The aggregating effect was associated with particles which were sedi- mented by centrifugation for 30 minutes at 10,000 G. By means of electron microscopy the particles were identified as cross-striated collagen fibrils.

scholarly journals Endotoxin-induced changes in human platelet membranes: morphologic evidence

Blood ◽  
1978 ◽  
Vol 51 (3) ◽  
pp. 487-495 ◽  
Author(s):  
DH Ausprunk ◽  
J Das
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Human Platelet ◽  
Human Platelets ◽  
Free Medium ◽  
Platelet Surface ◽  
Low Concentrations ◽  
Induced Changes ◽  
Scanning Electron

Abstract Interaction between human platelets and bacterial endotoxin was studied in vitro with transmission and scanning electron microscopy. Washed human platelets, whose aggregation was blocked with apyrase, were incubated in a plasma-free medium containing crude endotoxin that had previously been complexed with copper. Thirty minutes of incubation resulted in adherence of endotoxin particles to the platelet surface, breaks in the platelet plasma membrane with apparent attempts at repair, pseudoped formation, and centralization of platelet organelles. Copper appeared to potentiate these phenomena, since neither Cu2+ at low concentrations nor endotoxin alone altered the morphology of the platelet membrane. This platelet-endotoxin interaction may be an intermediary step in the detoxification and clearance of endotoxin from the plasma.

scholarly journals Endotoxin-induced changes in human platelet membranes: morphologic evidence

Blood ◽  
1978 ◽  
Vol 51 (3) ◽  
pp. 487-495
Author(s):  
DH Ausprunk ◽  
J Das
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Human Platelet ◽  
Human Platelets ◽  
Free Medium ◽  
Platelet Surface ◽  
Low Concentrations ◽  
Induced Changes ◽  
Scanning Electron

Interaction between human platelets and bacterial endotoxin was studied in vitro with transmission and scanning electron microscopy. Washed human platelets, whose aggregation was blocked with apyrase, were incubated in a plasma-free medium containing crude endotoxin that had previously been complexed with copper. Thirty minutes of incubation resulted in adherence of endotoxin particles to the platelet surface, breaks in the platelet plasma membrane with apparent attempts at repair, pseudoped formation, and centralization of platelet organelles. Copper appeared to potentiate these phenomena, since neither Cu2+ at low concentrations nor endotoxin alone altered the morphology of the platelet membrane. This platelet-endotoxin interaction may be an intermediary step in the detoxification and clearance of endotoxin from the plasma.

The Binding of Phosphatidylglycerol Liposomes to Rat Platelets Is Mediated by Complement

1990 ◽  
Vol 64 (01) ◽  
pp. 172-176 ◽  
Author(s):  
H C Loughrey ◽  
M B Bally ◽  
L W Reinish ◽  
P R Cullis
Keyword(s):  
Heat Treatment ◽  
Platelet Count ◽  
Human Platelet ◽  
Serum Complement ◽  
Factors Associated ◽  
Platelet Aggregates ◽  
Aggregation Of Platelets ◽  
Rat Platelets

SummaryPrevious work has shown that intravenous administration of phosphatidylglycercol (PG) containing liposomes to rats results in a rapid transient decline in platelet count (1). Here the interactions of PG liposomes with rat platelets in vitro have been examined with the aim of charactenzing factors associated with the decline. It is shown that PG liposomes induce formation of rat (but not human) platelet-liposome microaggregates in vitro. The PG liposome dependent thrombocytopenia observed in vivo can therefore be attributed to sequestration of PG liposome-platelet aggregates. Further, the aggregation of platelets with PG liposomes, which can be moni ored as a reduction in platelet count using a coulter counter, is shown to be mediated by a serum complement fgctor, likely C3b. This is indicated by a requirement of plasma for the in vitro reduction in platelet count induced by PG liposomes, and the inhibition of this effect by heat treatment of plasma, by incubation of plasma with purified cobra venom factor, or by removal of C3 from plasma.

Sem Studies of Co-Cr-Mo Surgical Implant Alloy Corrosion Behavior

1982 ◽  
Vol 40 ◽  
pp. 520-521
Author(s):  
Ann Chidester Van Orden ◽  
John L. Chidester ◽  
Anna C. Fraker ◽  
Pei Sung
Keyword(s):  
Electron Microscopy ◽  
Corrosion Behavior ◽  
Anodic Polarization ◽  
Saline Solution ◽  
Saturated Calomel Electrode ◽  
Physiological Saline ◽  
X Ray ◽  
Physiological Saline Solution ◽  
Scanning Electron

The influence of small variations in the composition on the corrosion behavior of Co-Cr-Mo alloys has been studied using scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), and electrochemical measurements. SEM and EDX data were correlated with data from in vitro corrosion measurements involving repassivation and also potentiostatic anodic polarization measurements. Specimens studied included the four alloys shown in Table 1. Corrosion tests were conducted in Hanks' physiological saline solution which has a pH of 7.4 and was held at a temperature of 37°C. Specimens were mechanically polished to a surface finish with 0.05 µm A1203, then exposed to the solution and anodically polarized at a rate of 0.006 v/min. All voltages were measured vs. the saturated calomel electrode (s.c.e.).. Specimens had breakdown potentials near 0.47V vs. s.c.e.

Maytansine-Induced Mitotic Arrest in Human Lymphoblasts

1977 ◽  
Vol 35 ◽  
pp. 460-461
Author(s):  
Tai-Te Chao ◽  
John Sullivan ◽  
Awtar Krishan
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Transmission Electron Microscopy ◽  
Tubulin Polymerization ◽  
Vinca Alkaloids ◽  
Antimitotic Activity ◽  
Transmission Electron ◽  
Flow Microfluorometry ◽  
Brain Tubulin

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.

Some Structural Features of Metaphase Chromosomes of Mice and Men

1967 ◽  
Vol 25 ◽  
pp. 190-191
Author(s):  
Godfrey C. Hoskins ◽  
Betty B. Hoskins
Keyword(s):  
Electron Microscopy ◽  
Electron Micrographs ◽  
Structural Features ◽  
Metaphase Chromosomes ◽  
The Future ◽  
Of Mice And Men ◽  
Mouse Cells ◽  
Human And Mouse

Metaphase chromosomes from human and mouse cells in vitro are isolated by micrurgy, fixed, and placed on grids for electron microscopy. Interpretations of electron micrographs by current methods indicate the following structural features.Chromosomal spindle fibrils about 200Å thick form fascicles about 600Å thick, wrapped by dense spiraling fibrils (DSF) less than 100Å thick as they near the kinomere. Such a fascicle joins the future daughter kinomere of each metaphase chromatid with those of adjacent non-homologous chromatids to either side. Thus, four fascicles (SF, 1-4) attach to each metaphase kinomere (K). It is thought that fascicles extend from the kinomere poleward, fray out to let chromosomal fibrils act as traction fibrils against polar fibrils, then regroup to join the adjacent kinomere.

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