scholarly journals Ultrastructural Study of Platelet Aggregation by Mouse 15091A Tumor Cells

1977 ◽  
Author(s):  
G.J. Stewart ◽  
R.A. Kuprionas ◽  
G.J. Gasic ◽  
J. Catalfamo ◽  
G.P. Gasic
Keyword(s):  
Platelet Aggregation ◽  
Tumor Cells ◽  
Lysosomal Enzymes ◽  
Culture Medium ◽  
Open Channel ◽  
Channel System ◽  
Transmission Electron ◽  
Spherical Vesicles ◽  
Aggregation Of Platelets ◽  
Soluble Material

Most tumor cells cause aggregation of platelets in heparinized plasma via material shed into culture medium. In this study we investigated the events by transmission electron microscopy. Freshly washed cells were covered with closely spaced microvilli, many of which pinched off during 1 hour of incubation at 37°C. Both cells and shed microvilli were membrane enclosed. Shed microvilli became spherical vesicles containing cytoplasm. Platelets aggregated when stirred with incubated tumor cells or shed material. The aggregates were composed of platelets that showed pseudopod formation, centralization of granules and increase in the open channel system. Platelets around the periphery of aggregates had bulbous portions free of granules (ballooning) but many granules remained in platelets in the interior of aggregates suggesting that release of lysosomal enzymes may have been somewhat limited. Aggregates resembled those induced by ADP rather than by thrombin. Tumor cells were not incorporated into the aggregates. Vesicles were not selectively associated with platelets prior to or during aggregation. While some vesicles were incorporated into aggregates, it appeared that this was a consequence rather than the cause of aggregation. Therefore, vesicles may have produced soluble material that induced platelet aggregation.

Adenosine Diphosphate (ADP) Breakdown in Human Plasma with Reference to Platelet Aggregation and Uraemia

1968 ◽  
Vol 19 (03/04) ◽  
pp. 438-450
Author(s):  
I. E. T Gan ◽  
B. G Firkin
Keyword(s):  
Platelet Aggregation ◽  
Human Plasma ◽  
Platelet Function ◽  
Adenosine Diphosphate ◽  
Plasma Enzyme ◽  
Aggregation Of Platelets ◽  
Plasma Activity

Summary1. A correlation between platelet aggregation and the plasma enzyme(s) ability to degrade Adenosine Diphosphate (ADP) has been confirmed.2. This plasma activity has been shown to be reduced in 6 patients with uraemia in whom platelet aggregation was demonstrably impaired but not in two whose platelet function was normal. The incorporation of 14C labelled ADP-8-14C was also only reduced in uraemic patients with abnormal platelet aggregation.3. These findings are discussed with particular reference to possible implication in mechanism involved in ADP aggregation of platelets.

The Influence of Ascorbic Acid on Platelet Structure and Function

1975 ◽  
Vol 34 (01) ◽  
pp. 050-062
Author(s):  
Dale H Cowan ◽  
Richard C Graham ◽  
Patricia Shook ◽  
Ronda Griffin
Keyword(s):  
Ascorbic Acid ◽  
Open Channel ◽  
Channel System ◽  
Short Intervals ◽  
Platelet Survival ◽  
Artifactual Changes ◽  
Survival Studies ◽  
And Function ◽  
Induced Aggregation ◽  
Platelet Structure

SummaryTo determine the effect on platelet behavior of transient exposure of platelets to ascorbic acid, studies of platelet function and ultrastructure were done before exposure to ascorbic acid at pH 6.5, during exposure to pH 6.5, and after restoration of pH to pre-acidifìcation levels. The effect of ascorbic acid (A. A.) was compared to that of HCl and citric acid (C. A.). ADP- and collagen-induced aggregation of normal platelets were significantly impaired by both A. A. and C. A. but were less affected by HCl. The release of 14C-serotonin was significantly reduced by each agent. The ultra-structure of normal platelets brought to pH 6.5 by A.A. was normal. After neutralization, there was marked dilatation of the open channel system and loss of the disc shape. When platelets were brought to pH 6.5 by A. A., then neutralized, the aggregates which formed after stimulation by ADP or collagen were smaller than normal, the platelets were less closely approximated, and degranulation was less complete. The data show that exposure of platelets to ascorbic acid for short intervals impairs their function when measured after restoration of pH to levels compatible with maximal responses. Platelet survival studies using autologous platelets labelled with 51Cr in the presence or absence of ascorbic acid showed that the recovery of normal platelets was unaffected by ascorbic acid, whereas recovery of platelets from patients with idiopathic thrombocytopenic purpura, idiopathic thrombocythemia, and alcohol-related thrombocytopenia was markedly reduced. The injury resulting from the use of ascorbic acid in preparing platelets for studies of platelet survival in patients with disorders affecting platelets may impair the recovery of the cells, resulting in artifactual changes in the survival studies.

On The Mechanism Of Heparin-Induced Potentiation Of Platelet Aggregation

1981 ◽  
Author(s):  
M Yamamoto ◽  
K Watanabe ◽  
Y Ando ◽  
H Iri ◽  
N Fujiyama ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Coagulation Factors ◽  
Marked Enhancement ◽  
Matrix Bound ◽  
Induced Aggregation ◽  
Aggregation Of Platelets ◽  
Plasma Heparin

It has been suggested that heparin caused potentiation of aggregation induced by ADP or epinephrine. The exact mechanism of heparin-induced platelet activation, however, remained unknown. In this paper, we have investigated the role of anti-thrombin III ( AT ) in heparin-induced platelet activation using purified AT and AT depleted plasma. When ADP or epinephrine was added to citrated PRP one minute after addition of heparin ( 1 u/ml, porcine intestinal mucosal heparin, Sigma Co. USA ), marked enhancement of platelet aggregation was observed, compared with the degree of aggregation in the absence of heparin. However, in platelet suspensions prepared in modified Tyrode’s solution, heparin exhibited no potentiating effect on platelet aggregation induced by epinephrine or ADP. Potentiation of epinephrine- or ADP-induced platelet aggregation by heparin was demonstrated when purified AT was added to platelet suspensions at a concentration of 20 μg/ml. AT depleted plasma, which was prepared by immunosorption using matrix-bound antibodies to AT, retained no AT, while determination of α1-antitrypsinα2- macroglobulin and fibrinogen in AT depleted plasma produced values which corresponded to those of the original plasma when dilution factor was taken into account. The activities of coagulation factors were also comparable to those of the original plasma. Heparin exhibited potentiating effect on ADP- or epinephrine-induced aggregation of platelets in original plasma, but no effect in AT depleted plasma. When purified AT was added back to AT depleted plasma at a concentration of 20 μg/ml, potentiation of platelet aggregation by heparin was clearly demonstrated.Our results suggest that effect of heparin on platelet aggregation is also mediated by anti-thrombin III.

Impairment of Ristocetin-Induced Platelet Aggregation in Patients with Infective Endocarditis

1994 ◽  
Vol 22 (1) ◽  
pp. 63-66
Author(s):  
M Matsumoto ◽  
H Murakami ◽  
T Matsushima ◽  
J Tamura ◽  
H Sadakata ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Infective Endocarditis ◽  
Plasma Factors ◽  
Induced Aggregation ◽  
Aggregation Of Platelets

An investigation was carried out on two patients with infective endocarditis associated with reduction of ristocetin-induced aggregation of platelets. The plasma of these patients reduced the aggregability with ristocetin of normal platelets. It is suggested that the patients had certain plasma factors which disturbed platelet aggregation with ristocetin.

Ultrastructural evidence of sperm dimorphism in Deladenus sp. (Tylenchomorpha: Sphaerularioidea: Allantonematidae)

Nematology ◽  
2007 ◽  
Vol 9 (3) ◽  
pp. 397-404 ◽  
Author(s):  
Hajime Kosaka ◽  
Manabu Kusunoki ◽  
Vladimir Yushin
Keyword(s):  
Electron Microscope ◽  
Parasitic Nematode ◽  
Spermatogenic Cells ◽  
Ultrastructural Evidence ◽  
Transmission Electron ◽  
Parallel Fibres ◽  
Sperm Dimorphism ◽  
Whole Life Cycle ◽  
First Time ◽  
Spherical Vesicles

AbstractThe dimorphic spermatozoa of the insect-parasitic nematode Deladenus sp. (Tylenchomorpha: Sphaerularioidea: Allantonematidae) were studied for the first time with a transmission electron microscope (TEM). The immature spermatozoa from the testis of mycetophagous males are 10-12 μm diam. and 4-5 μm long unpolarised cells with a centrally located nucleus without a nuclear envelope. The cytoplasm contains mitochondria and specific components, membranous organelles (MO) and fibrous bodies (FB). The MO are spherical vesicles with an internal system of finger-like invaginations of the membrane; the spindle-shaped FB consist of tightly packed parallel fibres. Spermatozoa from the uteri of infective females of Deladenus sp. are vastly different in size being tiny cells ca 2 μm diam. with a spherical or oval nucleus. Each cell contains several mitochondria and MO. Although each individual of Deladenus sp. contains only monomorphic spermatozoa, sperm dimorphism was revealed after analysis of the whole life cycle. Despite a difference in size the cytological characters of both types of spermatozoa conform to the typical rhabditid pattern. The presence of both MO and FB in sphaerularioidid spermatozoa differentiates the superfamily Sphaerularioidea from Tylenchoidea whose representatives lack MO in the spermatogenic cells.

scholarly journals ROS Promote Ox-LDL-Induced Platelet Activation by Up-Regulating Autophagy Through the Inhibition of the PI3K/AKT/mTOR Pathway

2018 ◽  
Vol 50 (5) ◽  
pp. 1779-1793 ◽  
Author(s):  
Xiang Wang ◽  
Yun-Feng Fu ◽  
Xiao Liu ◽  
Guo Feng ◽  
Dan Xiong ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Platelet Aggregation ◽  
Platelet Activation ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Mtor Pathway ◽  
Enhanced Chemiluminescence ◽  
Transmission Electron ◽  
Related Proteins

Background/Aims: Oxidized low-density lipoprotein (oxLDL) promotes unregulated platelet activation in patients with dyslipidemic disorders. Although oxLDL stimulates activating signaling, researchers have not clearly determined how these events drive accelerated thrombosis. Here, we describe the mechanism by which ROS regulate autophagy during ox-LDL-induced platelet activation by modulating the PI3K/AKT/mTOR signaling pathway. Methods: For in vitro experiments, ox-LDL, the ROS scavenger N-acetylcysteine (NAC), the mTOR inhibitor rapamycin and the autophagy inhibitor 3-MA were used alone or in combination with other compounds to treat platelets. Then, platelet aggregation was evaluated on an aggregometer and platelet adhesion was measured under shear stress. The levels of a platelet activation marker (CD62p) were measured by flow cytometry, reactive oxygen species (ROS) levels were then quantified by measuring DCFH-DA fluorescence intensity via flow cytometry. Nitric oxide (NO) and superoxide (O2·-) levels were determined by the nitric acid deoxidize enzyme method and lucigenin-enhanced chemiluminescence (CL), respectively. Transmission electron microscopy was used to observe the autophagosome formation, immunofluorescence staining was employed to detect LC3 expression and western blotting was used to measure the levels of PI3K/AKT/mTOR pathway- and autophagy-related proteins. Results: Ox-LDL-induced platelets showed a significant increase in platelet aggregation and adhesion, CD62p expression, ROS level and O2·- content, with an elevated LC3II/LC3I ratio and Beclin1 expression, but a dramatic reduction in the levels of p62 and pathway-related proteins (all P < 0.05). However, platelet activation and autophagy were aggravated by the Rapamycin treatment, and decreased following treatment with NAC, 3-MA, or NAC and 3-MA, together with increased activity of the PI3K/AKT/mTOR pathway. Additionally, decreased platelet activation and autophagy were observed in platelets treated with NAC and Rapamycin or Rapamycin and 3-MA compared with platelets treated with Rapamycin alone, suggesting that both NAC and 3-MA reversed the effects of Rapamycin. Conclusion: Inhibition of ROS production may reduce autophagy to suppress ox-LDL-induced platelet activation by activating PI3K/AKT/mTOR pathway.

scholarly journals Polyhydroxyalkanoates production by a bacterium isolated from mangrove soil samples collected from Quang Ninh province

2012 ◽  
Vol 3 (2) ◽  
pp. 76-79 ◽  
Author(s):  
Thuoc Van Doan ◽  
Binh Thi Nguyen
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Culture Medium ◽  
Carbon Sources ◽  
Nile Red ◽  
Soil Samples ◽  
Mangrove Soil ◽  
Transmission Electron ◽  
Bacterium Strain ◽  
Quang Ninh

A PHA producing bacterium (strain QN271) was selected from mangrove soil samples collected from Quang Ninh province by using the Nile red dying technique. PHA accumulation in the selected bacterium strain was confirmed by transmission electron microscope. With the exception of maltose or sucrose, the bacterium strain was found to be able to synthesize PHA from various carbon sources (glucose, xylose, fructose, glycerol, and glucose plus propionate). The strain accumulated poly(3-hydroxybutyrate) from glucose, fructose, xylose, and glycerol whereas poly(3-hydroxybutyrate-co-3-hydroxyvalarate) was produced when a combination of glucose and propionate was included in the culture medium. Fructose was found to be most suitable substrate for PHA synthesis by strain QN271. PHA content of 63.3% and CDW of 6 g/L were obtained after 32 hrs of cultivation in fructose medium. Chủng vi khuẩn có khả năng sinh tổng hợp PHA đã được phân lập từ đất rừng ngập mặn tỉnh Quảng Ninh nhờ kỹ thuật nhuộm với Nile red. Ảnh quan sát dưới kính hiển vi điện tử dẫn truyền chứng tỏ rằng chủng vi khuẩn này có khả năng tích lũy lượng lớn PHA trong tế bào. Chủng vi khuẩn tuyển chọn có khả năng sinh tổng hợp PHA từ nhiều nguồn các bon khác nhau như glucose, xylose, fructose, glucerol, glucose và propionate nhưng không có khả năng tổng hợp PHA từ maltose hoặc saccharose. Chủng vi khuẩn tuyển chọn tổng hợp poly (3-hydroxybutyrate) từ các nguồn các-bon như glucose, xylose, fructose, hay glycerol, trong khi đó poly (3-hydroxybutyrate-co-3-hydroxyvalarate) sẽ được tổng hợp khi phối hợp sử dụng hai nguồn các-bon (glucose và propionate). Fructose là nguồn các-bon tốt nhất cho chủng QN271 sinh tổng hợp PHA, khi nuôi cấy trong môi trường có fructose chủng vi khuẩn này có thể tạo ra lượng sinh khối là 6 g/L trong đó có chứa 63.3% PHA sau 32 giờ.

scholarly journals Ultrastructural calli analysis of Inga vera Willd. subsp. Affinis (DC.) T.D. Penn

2010 ◽  
Vol 34 (5) ◽  
pp. 789-796 ◽  
Author(s):  
Vanessa Cristina Stein ◽  
Renato Paiva ◽  
Daiane Peixoto Vargas ◽  
Fernanda Pereira Soares ◽  
Eduardo Alves ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Culture Medium ◽  
Cell Development ◽  
Nodal Segments ◽  
Nodal Segment ◽  
Ms Medium ◽  
Flower Buds ◽  
Embryo Formation ◽  
Transmission Electron ◽  
Explant Source

Subcellular changes are relevant to understand plant organogenesis and embryogenesis in the early stages of cell development. The cytology during cell development in tissue culture is however still poorly characterized. This study aimed to characterize the ultrastructural differences related to callogenesis of anthers, ovaries, leaf and nodal segments of Inga vera Willd. subsp. Affinis (DC.) T.D. Penn. Flower buds, nodal segments and leaves were disinfected and inoculated in test tubes containing MS medium with 3% sucrose and 4.5µM 2.4-D, except for leaf callogenesis, where 9µM of this auxin was used, and for the callogenesis of anthers and ovaries, where the culture medium was enriched with 0.25% activated charcoal and 90µM PVP. After 45 days in culture medium, the anther, ovary, leaf and nodal segment calli were fixed in Karnovisky and prepared for visualization by scanning and transmission electron microscopy. Ultrastructural differences were observed among the callus cells of anthers, ovaries, segments and leaves. There was no evidence of somatic embryo formation in the anther, leaf and nodal segment calli, in spite of some embryogenic characteristics in the cells. The ovary calli, with indications of embryo formation, seem to be the most responsive explant source for embryogenesis.

Paracrystalline bundles of large tubules, induced in vitro by Mebendazole in Cysticercus cellulosae

Parasitology ◽  
1981 ◽  
Vol 83 (3) ◽  
pp. 513-518 ◽  
Author(s):  
J. P. Laclette ◽  
Marie Therese Merchant ◽  
Kaethe Willms ◽  
L. Cañedo
Keyword(s):  
Electron Microscopy ◽  
Culture Medium ◽  
Morphological Changes ◽  
Bladder Wall ◽  
Secretory Cells ◽  
External Diameter ◽  
Nematode Larvae ◽  
Transmission Electron ◽  
Cysticercus Cellulosae

SUMMARYThe effect of the anthelmintic Mebendazole on Cysticercus cellulosae maintained in culture medium was studied by transmission electron microscopy. In addition to the well-known morphological changes induced by Mebendazole in other cestode and nematode larvae, it also induced the cytoplasmic appearance of paracrystalline bundles in the secretory cells of the bladder wall. These bundles were formed by groups of large parallel tubules arranged in a hexagonal-like pattern. The tubules, which had an external diameter of about 50 nm and a length that might exceed 5 μm, were surrounded by a matrix and a distance between neighbouring tubules of 80–120 nm centre to centre was estimated. The tubules were stable to colchicine and low temperature. The temporary appearance of bundles is described and some alternative explanations on their origin are advanced.

scholarly journals Secretion of β-N-acetylglucosaminidase isoenzymes by normal human fibroblasts

1978 ◽  
Vol 173 (2) ◽  
pp. 433-439 ◽  
Author(s):  
P Willcox
Keyword(s):  
Lysosomal Enzyme ◽  
Human Fibroblast ◽  
Lysosomal Enzymes ◽  
Culture Medium ◽  
Human Fibroblasts ◽  
The Other ◽  
Normal Human Fibroblast ◽  
Acid Hydrolases ◽  
Human Fibroblast Cultures ◽  
Normal Human

1. Secretion of the lysosomal enzyme beta-N-acetylglucosaminidase (EC 3.2.1.30) by normal human fibroblast cultures was linear with respect to time up to 96h. 2. Two forms of the A isoenzyme of beta-N-acetylglucosaminidase were found in the culture medium. One form was similar to the isoenzyme found in other extracellular fluids, such as plasma and tears, the other resembled the intracellular (lysosomal) enzyme. The presence of the two isoenzymes in the culture medium appears to reflect two distinct secretory processes. 3. It is suggested that plasma acid hydrolases may be destined for incorporation into lysosomes in a manner analogous to that described for the packaging of lysosomal enzymes by fibroblasts.

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