scholarly journals Electrocardiographic Imaging of Repolarization Abnormalities

2021 ◽  
Vol 10 (9) ◽  
Author(s):  
Laura R. Bear ◽  
Matthijs Cluitmans ◽  
Emma Abell ◽  
Julien Rogier ◽  
Louis Labrousse ◽  
...  
Keyword(s):  
Sinus Rhythm ◽  
Correlation Coefficient ◽  
Ex Vivo ◽  
Data Sets ◽  
Human Donor ◽  
Electrocardiographic Imaging ◽  
Significant Difference ◽  
Highly Correlated ◽  
Repolarization Abnormalities

Background Dispersion and gradients in repolarization have been associated with life‐threatening arrhythmias, but are difficult to quantify precisely from surface electrocardiography. The objective of this study was to evaluate electrocardiographic imaging (ECGI) to noninvasively detect repolarization‐based abnormalities. Methods and Results Ex vivo data were obtained from Langendorff‐perfused pig hearts (n=8) and a human donor heart. Unipolar electrograms were recorded simultaneously during sinus rhythm from an epicardial sock and the torso‐shaped tank within which the heart was suspended. Regional repolarization heterogeneities were introduced through perfusion of dofetilide and pinacidil into separate perfusion beds. In vivo data included torso and epicardial potentials recorded simultaneously in anesthetized, closed‐chest pigs (n=5), during sinus rhythm, and ventricular pacing. For both data sets, ECGI accurately reconstructed T‐wave electrogram morphologies when compared with those recorded by the sock (ex vivo: correlation coefficient, 0.85 [0.52–0.96], in vivo: correlation coefficient, 0.86 [0.52–0.96]) and repolarization time maps (ex‐vivo: correlation coefficient, 0.73 [0.63–0.83], in vivo: correlation coefficient, 0.76 [0.67–0.82]). ECGI‐reconstructed repolarization time distributions were strongly correlated to those measured by the sock (both data sets, R 2 ≥0.92). Although the position of the gradient was slightly shifted by 8.3 (0–13.9) mm, the mean, max, and SD between ECGI and recorded gradient values were highly correlated ( R 2 =0.87, 0.75, and 0.86 respectively). There was no significant difference in ECGI accuracy between ex vivo and in vivo data. Conclusions ECGI reliably and accurately maps potentially critical repolarization abnormalities. This noninvasive approach allows imaging and quantifying individual parameters of abnormal repolarization‐based substrates in patients with arrhythmogenesis, to improve diagnosis and risk stratification.

scholarly journals Predicting chromosome damage in astronauts participating in international space station missions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alan Feiveson ◽  
Kerry George ◽  
Mark Shavers ◽  
Maria Moreno-Villanueva ◽  
Ye Zhang ◽  
...  
Keyword(s):  
International Space Station ◽  
Dose Response ◽  
Ex Vivo ◽  
Space Station ◽  
Space Radiation ◽  
Blood Samples ◽  
International Space ◽  
Significant Difference ◽  
Subject Specific

AbstractSpace radiation consists of energetic protons and other heavier ions. During the International Space Station program, chromosome aberrations in lymphocytes of astronauts have been analyzed to estimate received biological doses of space radiation. More specifically, pre-flight blood samples were exposed ex vivo to varying doses of gamma rays, while post-flight blood samples were collected shortly and several months after landing. Here, in a study of 43 crew-missions, we investigated whether individual radiosensitivity, as determined by the ex vivo dose–response of the pre-flight chromosome aberration rate (CAR), contributes to the prediction of the post-flight CAR incurred from the radiation exposure during missions. Random-effects Poisson regression was used to estimate subject-specific radiosensitivities from the preflight dose–response data, which were in turn used to predict post-flight CAR and subject-specific relative biological effectiveness (RBEs) between space radiation and gamma radiation. Covariates age, gender were also considered. Results indicate that there is predictive value in background CAR as well as radiosensitivity determined preflight for explaining individual differences in post-flight CAR over and above that which could be explained by BFO dose alone. The in vivo RBE for space radiation was estimated to be approximately 3 relative to the ex vivo dose response to gamma irradiation. In addition, pre-flight radiosensitivity tended to be higher for individuals having a higher background CAR, suggesting that individuals with greater radiosensitivity can be more sensitive to other environmental stressors encountered in daily life. We also noted that both background CAR and radiosensitivity tend to increase with age, although both are highly variable. Finally, we observed no significant difference between the observed CAR shortly after mission and at > 6 months post-mission.

scholarly journals A Tumbling Magnetic Microrobot System for Biomedical Applications

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 861
Author(s):  
Elizabeth E. Niedert ◽  
Chenghao Bi ◽  
Georges Adam ◽  
Elly Lambert ◽  
Luis Solorio ◽  
...  
Keyword(s):  
Ultrasound Imaging ◽  
Biomedical Applications ◽  
Imaging System ◽  
Ex Vivo ◽  
Negative Control ◽  
Circular Path ◽  
Rotational Axis ◽  
Significant Difference

A microrobot system comprising an untethered tumbling magnetic microrobot, a two-degree-of-freedom rotating permanent magnet, and an ultrasound imaging system has been developed for in vitro and in vivo biomedical applications. The microrobot tumbles end-over-end in a net forward motion due to applied magnetic torque from the rotating magnet. By turning the rotational axis of the magnet, two-dimensional directional control is possible and the microrobot was steered along various trajectories, including a circular path and P-shaped path. The microrobot is capable of moving over the unstructured terrain within a murine colon in in vitro, in situ, and in vivo conditions, as well as a porcine colon in ex vivo conditions. High-frequency ultrasound imaging allows for real-time determination of the microrobot’s position while it is optically occluded by animal tissue. When coated with a fluorescein payload, the microrobot was shown to release the majority of the payload over a 1-h time period in phosphate-buffered saline. Cytotoxicity tests demonstrated that the microrobot’s constituent materials, SU-8 and polydimethylsiloxane (PDMS), did not show a statistically significant difference in toxicity to murine fibroblasts from the negative control, even when the materials were doped with magnetic neodymium microparticles. The microrobot system’s capabilities make it promising for targeted drug delivery and other in vivo biomedical applications.

scholarly journals Neuraminidase inhibitors rewire neutrophil function in vivo in murine sepsis and ex vivo in COVID-19

2020 ◽  
Author(s):  
Rodrigo O. Formiga ◽  
Flávia C. Amaral ◽  
Camila F. Souza ◽  
Daniel A. G. B. Mendes ◽  
Carlos W. S. Wanderley ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Ex Vivo ◽  
Neutrophil Function ◽  
Human Neutrophils ◽  
Data Sets ◽  
Neuraminidase Inhibitors ◽  
Severe Infections ◽  
Whole Blood Cells ◽  
Neutrophil Dysfunction

ABSTRACTNeutrophil overstimulation plays a crucial role in tissue damage during severe infections. Neuraminidase (NEU)-mediated cleavage of surface sialic acid has been demonstrated to regulate leukocyte responses. Here, we report that antiviral NEU inhibitors constrain host NEU activity, surface sialic acid release, ROS production, and NETs released by microbial-activated human neutrophils. In vivo, treatment with Oseltamivir results in infection control and host survival in peritonitis and pneumonia models of sepsis. Single-cell RNA sequencing re-analysis of publicly data sets of respiratory tract samples from critical COVID-19 patients revealed an overexpression of NEU1 in infiltrated neutrophils. Moreover, Oseltamivir or Zanamivir treatment of whole blood cells from severe COVID-19 patients reduces host NEU-mediated shedding of cell surface sialic acid and neutrophil overactivation. These findings suggest that neuraminidase inhibitors can serve as host-directed interventions to dampen neutrophil dysfunction in severe infections.

Comparison of the Predictive Value of MRD and PVA Score in Pediatric ALL.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1520-1520
Author(s):  
Anja Troeger ◽  
Gabriele Escherich ◽  
Udo zur Stadt ◽  
M. L Den Boer ◽  
Rob Pieters ◽  
...  
Keyword(s):  
Multivariate Analysis ◽  
Correlation Coefficient ◽  
Predictive Value ◽  
Genetic Alterations ◽  
Relevant Parameter ◽  
Response To Chemotherapy ◽  
Significant Difference ◽  
The Impact

Abstract Early identification of patients (pts) at risk for relapse allows for development of risk-adapted treatment strategies, thus steadily improving the outcome in pediatric acute lymphoblastic leukemia (ALL). Besides classic prognostic factors such as age, initial leukocyte count (WBC), genetic alterations and the immune phenotype, the so called PVA Score, summarizing the in vitro resistance of blasts against prednisone, vincristine and asparaginase, has been applied for treatment stratification in the CoALL protocol, a German multicenter study for children with ALL. Over the past years it has become increasingly clear that the in vivo response to chemotherapy assessed by detection of residual malignant cells (MRD) by PCR technique can be predictive of prognosis. Here we compare for the first time the relevance of in vitro (PVA Score) and in vivo (MRD) treatment response in a large cohort of 275 children with ALL, age 1–17 years, uniformly treated according to the CoALL protocols 05–92 to 07–03. Children with B cell precursor ALL (BCP-ALL) and T-ALL were analyzed separately. Bone marrow samples of 160 children with BCP-ALL and of 115 T-ALL pts diagnosed between 1992–2005 were prospectively assessed for PVA Score at diagnosis and MRD levels at day (d) 15, 29 and 43 after informed consent was obtained from the parents or legal guardians at the time of enrolment. Of note, 7 of the BCP-ALL and 14 of the T-ALL pts with late morphological response were excluded from analysis. Overall median MRD levels in BCP-ALL pts (MRDd15: 6×10e-4; MRDd29: 2×10e-5) were one log lower than in T-ALL (MRDd15: 9×10e-3; MRDd29: 3×10e-4). We detected no association between PVA Score and MRD level in BCP-ALL (correlation coefficient: r=0.15; p=0.15) and only a weak correlation in T-ALL pts (correlation coefficient: r=0.43; p=0.0003). When assessing the impact of the PVA Score on relapse free survival (RFS), in BCP-ALL only score 3+4 (good response) vs. 8+9 (poor response) was prognostically relevant (RFS 0.86±0.05 vs. 0.59±0.12; p=0.03), whereas in T-ALL no significant difference between these subgroups was found (RFS 0.71±0.1 vs. 0.68±0.1; p=0.62). In multivariate analysis PVA Score 3+4 vs. 8+9 remained the most relevant parameter for RFS in BCP-ALL (p=0.05) when compared to age and initial WBC. However, MRD levels were of even higher predictive power, especially at later time points: MRD negativity at d29 in BCP-ALL identified pts with significantly superior RFS (RFS MRD neg.: 0.9±0.05 vs. pos.: 0.7±0.05; p=0.003) and low MRD levels indicated a favorable outcome in T-ALL (RFS MRD <10e-3: 0.89±0.05 vs. MRD >10e-3: 0.68±0.07; p=0.001). Moreover, both BCP-ALL and T-ALL pts characterized by MRD levels >10e-3 on d43 exhibited a poor outcome (RFS BCP-ALL: 0.42±0.17; RFS T-ALL: 0.47±0.14). MRD remained an independent marker in multivariate analysis including initial WBC and age, both in BCP- (MRDd29: p=0.006; MRDd43: p=0.001) and T-ALL (MRDd29: p=0.003; MRDd43: p=0.015). By multivariate analysis, in T-ALL low MRD levels on d29 predicted superior RFS independently from the PVA Score (MRD: p=0.002 vs. PVA: p=0.09), whereas in BPC-ALL these parameters were not completely independent from each other at that early time point (MRD: p= 0.059 vs. PVA: p= 0.063) but became independent at d43 (MRD: p= 0.018 vs. PVA: p= 0.253). While the predictive value of the PVA Score was limited to BCP-ALL, MRD was an independent prognostic marker for both BCP- and T-ALL and reliably identified pts at low and high risk for relapse.

Insights Into Thrombopoiesis From Infused Human Megakaryocytes Into Mice

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1165-1165
Author(s):  
Yuhuan Wang ◽  
Vincent M. Hayes ◽  
Prasuna Paluru ◽  
Stella T. Chou ◽  
Deborah L. French ◽  
...  
Keyword(s):  
Half Life ◽  
Size Range ◽  
Conflicts Of Interest ◽  
Ex Vivo ◽  
Human Donor ◽  
Nsg Mice ◽  
Infusion Study ◽  
Recipient Animal ◽  
Post Infusion

Abstract Thrombopoiesis is the process by which megakaryocytes (Megs) release platelets (Plts), but issues remain as to the detailed in vivo mechanisms underlying this process. We now report new insights into this process by studying infused human Megs into immunocompromized NOD/SCID, gamma-interferon deleted (NSG) mice. Prior in situ microscopy has suggested that Megs release varied-size cytoplasmic fragments up to whole Megs in size into the medullary vascular space. Other studies have suggested that at least a portion of thrombopoiesis occurs by Megs lodged in the lungs. We previously infused ex vivo-generated murine Megs into mice and found that these Megs become entrapped in the animals’ lungs, and in <1.5 hrs, release functional Plts (termed here “Meg-Plts”) that have a similar half-life as infused mouse donor-derived Plts (termed here “Donor-Plts”). To better understand the biology of thrombopoiesis, we have infused ex vivo-generated human Megs into NSG mice. These studies replicated many of the observations seen with infused murine Megs: Human Megs were entrapped in the lungs with delayed release of human Meg-Plts, and these Meg-Plts had the same half-life as infused human Donor-Plts. Human Plts differ from murine Plts in size so this parameter was analyzed following infusion of human Megs using forward cell scatter analysis. We noted that 10 mins post-infusion, the Meg-Plt size range was wide and displayed a non-bell-shaped distribution. This distribution was in contrast to the tight bell-shaped curves seen for the endogenous murine Plts and for infused human Donor-Plts. However, by 3 hrs post-human Meg infusion - at the time of peak Meg-Plt counts - the human Meg-Plts now displayed an identical bell-shaped distribution curve as infused human Donor-Plt. The smaller, human Meg-Plts had disappeared. The size and distribution of these Meg-Plts then remained near identical to Donor-Plts for the remaining portion of the 48 hr post-infusion study. However, after impairing macrophage clearance in NSG recipient mice with clodronate-ladened liposome infusion, the small Meg-Plts did not disappear and were present at 48 hrs. Using thiazole orange (TO) to stain platelets for RNA content, we noted that ∼70% of all Meg-Plts were initially TO+ compared to the steady-state of ∼10% for mouse endogenous platelets. This high TO+ state decreased to near 10% by 24 hrs post-infusion. Up to ∼6 hrs, all of the large Meg-Plts were TO+, while the smaller-sized Meg-Plts were predominantly TO-. Unless the mice were treated with clodronate-ladened liposomes, these TO-, small Meg-Plts disappeared before 6 hrs. In conclusion, these data support that ex vivo-generated human Megs release physiologic platelets in the pulmonary vascular bed of NSG mice with the same size range/distribution and survival as infused human Donor-Plts. Mean Meg-Plt size depends on the species of origin of the infused Megs rather than on the species of the recipient animal. We did not detect large Meg cytoplasmic fragments that underwent further size reduction although our technique may not be capable of detecting small numbers of such fragments or the small size changes that would accompany platelet maturation from preplatelets. Our data also suggest that Megs generated in culture release a wide size range of non-physiologic Plt-like particles that when infused are cleared rapidly by macrophages. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Ex vivo and in vivo study of Kowa HA-2 applanation tonometer in the measurement of intraocular pressure in cats

2017 ◽  
Vol 38 (6) ◽  
pp. 3647
Author(s):  
Claudia Lizandra Ricci ◽  
Rogério Giuffrida ◽  
Glaucia Prada Kanashiro ◽  
Hilidia Stephania Rufino Belezzi ◽  
Carolina De Carvalho Bacarin ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Ex Vivo ◽  
Clinical Signs ◽  
In Vivo Study ◽  
Eye Drops ◽  
Significant Difference ◽  
Applanation Tonometer ◽  
Ex Vivo Study ◽  
Healthy Eyes

The objective of this study was to evaluate the use of the Kowa HA-2 applanation tonometer in measuring intraocular pressure (IOP) in cats. Ten healthy eyes were used in an ex vivo study in which the calibration curve for manometry vs. tonometry was determined by artificially raising the IOP in 5 mmHg increments up to 60 mmHg (10-60 mmHg). Both eyes of 10 anesthetized cats were studiedin vivo to compare manometry vs. tonometry. In the ambulatory study, 78 healthy eyes, 7 eyes with glaucoma and 20 eyes with uveitis were evaluated by tonometry, which was performed with topical anesthesia and 1% fluorescein eye drops for the formation of fluorescein semicircles. The correlation coefficient (r²) between the manometer and the Kowa HA-2 tonometer was 0.993 and the linear regression equation was y = 0.0915x + 0.0878 in the ex-vivo study. In the in vivo study, the IOP values (mean±SD, in mmHg) in manometry were 15.6 ± 1.1(14.0 – 17.5) and in tonometry were 15.5 ± 1.2(13.5 – 17.2), with no significant difference (P > 0.05) between manometry and tonometry. In ambulatory study, using the Kowa HA-2 tonometer, the IOP values (mean±SD, in mmHg) were 15.0 ± 1.5 (11.8 – 18.3) for the healthy eyes, 38.4 ± 8.1(29.6 – 53.7) for glaucomatous eyes and 10.4 ± 2.0(5.3 – 12.2) for eyes with uveitis. There was a strong correlation and accuracy between the IOP values with the manometry and the Kowa HA-2 tonometer. In the ambulatorystudy the IOP values obtained with the tonometer were compatible for animals with healthy eyes and with clinical signs of glaucoma and uveitis. We conclude that the Kowa HA-2 tonometer can be used in the measurement of IOP in cats, since it is a practical and accurate method in this species.

scholarly journals Effect of Doxycycline on Survival in Abdominal Aortic Aneurysms in a Mouse Model

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Lisa C. Adams ◽  
Julia Brangsch ◽  
Jan O. Kaufmann ◽  
Dilyana B. Mangarova ◽  
Jana Moeckel ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Ex Vivo ◽  
Endothelial Damage ◽  
Aortic Aneurysms ◽  
Clinical Dose ◽  
Doxycycline Treatment ◽  
Abdominal Aortic ◽  
Significant Difference ◽  
Aneurysm Growth

Background. Currently, there is no reliable nonsurgical treatment for abdominal aortic aneurysm (AAA). This study, therefore, investigates if doxycycline reduces AAA growth and the number of rupture-related deaths in a murine ApoE−/− model of AAA and whether gadofosveset trisodium-based MRI differs between animals with and without doxycycline treatment. Methods. Nine ApoE−/− mice were implanted with osmotic minipumps continuously releasing angiotensin II and treated with doxycycline (30 mg/kg/d) in parallel. After four weeks, MRI was performed at 3T with a clinical dose of the albumin-binding probe gadofosveset (0.03 mmol/kg). Results were compared with previously published wild-type control animals and with previously studied ApoE−/− animals without doxycycline treatment. Differences in mortality were also investigated between these groups. Results. In a previous study, we found that approximately 25% of angiotensin II-infused ApoE−/− mice died, whereas in the present study, only one out of 9 angiotensin II-infused and doxycycline-treated ApoE−/− mice (11.1%) died within 4 weeks. Furthermore, doxycycline-treated ApoE−/− mice showed significantly lower contrast-to-noise (CNR) values ( p = 0.017 ) in MRI compared to ApoE−/− mice without doxycycline treatment. In vivo measurements of relative signal enhancement (CNR) correlated significantly with ex vivo measurements of albumin staining (R2 = 0.58). In addition, a strong visual colocalization of albumin-positive areas in the fluorescence albumin staining with gadolinium distribution in LA-ICP-MS was shown. However, no significant difference in aneurysm size was observed after doxycycline treatment. Conclusion. The present experimental in vivo study suggests that doxycycline treatment may reduce rupture-related deaths in AAA by slowing endothelial damage without reversing aneurysm growth.

Trastuzumab versus MYL-1401O (a proposed trastuzumab biosimilar) in a phase I bioequivalence study: In vivo and in vitro immunomodulation.

2017 ◽  
Vol 35 (7_suppl) ◽  
pp. 10-10
Author(s):  
Régine Audran ◽  
Haithem Chtioui ◽  
Anne-Christine Thierry ◽  
Carole Mayor ◽  
Laure Vallotton ◽  
...  
Keyword(s):  
Phase I ◽  
Mononuclear Cell ◽  
Ex Vivo ◽  
Reference Drug ◽  
Gm Csf ◽  
Significant Difference ◽  
Ifn Γ ◽  
The Impact

10 Background: Trastuzumab is a humanized monoclonal antibody targeting breast cancer cells overexpressing the HER2-oncoprotein. During a Phase-I single centre, single dose, randomized, double-blind, cross-over study assessing the bioequivalence of a proposed trastuzumab biosimilar (MYL-1401O) versus the initially marketed drug (Herceptin), we investigated in addition a large panel of pharmacodynamics parameters comparing the immunomodulatory activity of both drugs. Methods: 22 healthy males were included, 19 subjects receiving randomly a single intravenous infusion of MYL-1401O and 22 of Herceptin, separated by 16 to 22 week wash-out. Blood samples drawn pre- and post- infusion were assessed for in vivo serum cytokines induction (IL-1β, IL-2, IL-6, IL-10, IL-12, TNF-α, GM-CSF and IFN-γ) whereas the impact of treatment on mononuclear cell subsets and their level of activation was tested ex vivo. Volunteers’ PBMC (peripheral blood monocnuclear cells) were stimulated in vitro with recall antigens and mitogen for cytokine production. At baseline, we performed in addition a cytokine release assay on PBMC upon stimulation with trastuzumab as a preclinical safety test. Results: Trastuzumab infusion induced a transient and weak peak of serum IL-6 at 6h, and a modulation of mononuclear cell subset profile and level of activation. Notably CD16+ cells frequency decreased at 3h and peaked at 48h. Except for CD8+ T cells, there were no significant differences between Herceptin and its proposed biosimilar ex vivo. PBMC stimulated in vitro with trastuzumab secreted IL-6, TNF-a, IL-1β, GM-CSF, IFN-γ, and IL-10, but no IL-2. There was no significant difference between the two mAbs. Conclusions: Based on these in vivo, ex vivo and in vitro experiments, there is a strong assumption that MYL-1401O is biosimilar to the reference drug Herceptin for its immunomodulation properties as already proven for its bioequivalence. Clinical trial information: 2011-001406-94.

Survivin Is Required for Proliferation, but Not Polyploidization of Megakaryocytes.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1328-1328
Author(s):  
Jeremy Q Wen ◽  
Cindy Leung ◽  
Zan Huang ◽  
Sara Small ◽  
John Crispino
Keyword(s):  
Bone Marrow ◽  
Ex Vivo ◽  
Survivin Expression ◽  
Annexin V ◽  
Retroviral Infection ◽  
Hematopoietic Stem ◽  
Significant Difference ◽  
Megakaryocyte Progenitors

Abstract Survivin is a member of chromosome passenger complex, which plays an important role in chromosome alignment, separation and cytokinesis. We recently reported that survivin is necessary for the proliferation and survival of hematopoietic stem and progenitor cells. Furthermore, we previously showed that reduced levels of survivin expression facilitates megakaryocyte development, whereas elevated levels of survivin inhibit their maturation and polyploidization. However, the extent to which survivin is necessary for polyploidization and terminal differentiation of committed megakaryocytes remains unclear. To determine whether survivin is required for megakaryocyte and platelet biogenesis, we mated mice with floxed alleles of survivin (sur fl/fl) to mice that express Cre recombinase under the control of the PF4 promoter. Compound mutant animals appeared grossly normal and harbored normal platelet counts. Furthermore, survivin deleted and control littermates displayed similar expression of CD41 and CD42, as well as similar DNA content within the CD41+ population. The only significant difference detected was an increase in annexin V staining of CD41+ cells within the bone marrow of the mice with survivin deletion. Analysis of DNA extracted from these bone marrows showed no evidence of the survivin deletion, indicating that the surviving cells all escaped excision. These in vivo findings are consistent with a requirement for survivin in the survival or proliferation of megakaryocyte progenitors. Next, to induce megakaryocyte development ex vivo, we cultured bone marrow from surv fl/fl mice in vitro in the presence of TPO. Using this approach, we were able to induce survivin deletion in 75% of the cells as evidenced by PCR. Despite the deletion of survivin, polyploidization of the ex vivo generated megakaryocytes was unaffected. Finally, we induced deletion of survivin by retroviral infection of surv fl/fl progenitors with MSCV-Cre and found that megakaryocyte polyploidization was actually increased in the excised population. Taken together, our results suggest that survivin is not required for polyploidization, but is necessary for proliferation of megakaryocyte progenitors.

A Critical Investigation into the Existence of Circulating Platelet Aggregates

1986 ◽  
Vol 56 (01) ◽  
pp. 045-049 ◽  
Author(s):  
A R Saniabadi ◽  
G D O Lowe ◽  
R Madhok ◽  
K Spowart ◽  
B Shaw ◽  
...  
Keyword(s):  
Whole Blood ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
Venous Blood ◽  
White Blood Cells ◽  
Blood Platelet ◽  
Blood Collection ◽  
Significant Difference ◽  
Platelet Aggregates

SummaryBy a method of counting single platelets in diluted whole blood, platelet aggregates were quantified ex-vivo. Four groups: 20 thrombotic patients, 10 non-thrombotic patients, 10 healthy old controls and 10 healthy young controls were included in the study. Using a 19 gauge needle, with and without tubing, venous blood was taken into buffered EDTA, as a disaggregating agent and buffered EDTA-formalin, as the fixative. The amount of platelet aggregates quantified was affected by the quality of venepuncture or the rate of blood flow through the needle, but was unaffected by the presence of the tubing. There was no statistically significant difference between the four groups, in terms of the platelet aggregates quantified, but scanning electron microscopy revealed the presence of irreversible aggregates, composed of platelet red and white blood cells, in the blood of a greater number of thrombotic patients than non-thrombotic or healthy controls. Platelet aggregates were also quantified in aliquots of platelet rich plasma, and were found to be significantly greater than the corresponding values in whole blood. The difference appeared to be due to increased viscosity of the plasma, induced by the fixative which reduces platelet mobility during centrifugation. It is concluded that the platelet aggregates which disaggregate in bufffered EDTA may represent an artifact of blood collection; the irreversible aggregates are suspected to represent the in vivo circulating aggregates.

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