bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leptin-Mediated Activation of Human Platelets: Involvement of a Leptin Receptor and Phosphodiesterase 3A Cellular Signaling Complex.
Authors: Elbatarny Hisham S. , Maurice Donald H. 
Published: October 2019

Abstract
Leptin, a 16-KDa peptide-hormone produced primarily by adipocytes, was reported previously to promote platelet aggregation by a yet undefined mechanism. In this study, we investigated the effect of leptin on human platelet activation and delineate a molecular basis for this effect. Thus, we report that leptin potentiates ADP-induced platelet aggregation and directly stimulates adhesion of platelets to fibronectin. Using a combination of pharmacological and biochemical approaches we demonstrate that leptin mediates these effects by activating a signaling cascade that includes the leptin receptor (OB-R) and the kinases Jak2, phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB/Akt). Consistent with an important role for PKB-mediated phosphorylation and activation of the dominant cAMP hydrolyzing phosphodiesterase, phosphodiesterase 3A (PDE3A), in this system, incubation of platelets with leptin activated PDE3A and stimulated a PKB-mediated phosphorylation of PDE3A. A selective PDE3 inhibitor, cilostamide, attenuated leptin effects in these cells. While leptin did not alter platelet cAMP levels, our identification of an OB-R/PDE3A complex is consistent with leptin acting locally to regulate a “pool” of cAMP that controls platelet activity. This is the first report of leptin-induced platelet adhesion which provides a mechanistic basis for this potentially important effect of this peptide hormone.
Murine Platelets Expressing a Polymorphism of Integrin β3 Associated with Acute Coronary Thrombosis in Humans.
Authors: Wilcox David A. , Fang Juan , Johnson Bryon D. 
Published: October 2019

Abstract
Inheritance of a naturally occurring polymorphism of the human integrin β3-subunit at amino acid 33 causes a change from Leu to Pro that has been implicated as a risk factor for thrombotic complication in humans. It is unclear; however, if Pro (also known as the platelet alloantigen PlA2 form of β3) can alter integrin activation to significantly affect platelet function in vivo, since some clinical studies do not corroborate the initial findings. Since PlA2 is a frequent variant of β3 expressed on 28% of platelets from Americans the impact of this genetic variation on platelet function could have widespread clinical relevance; therefore, we developed a murine model to determine if expression of this common polymorphism of human integrin β3 can increase platelet function and lead to an increased propensity for thrombosis within a homogeneous population of mice. This model eliminates issues arising from variation in the genetic make-up, physical environment, and/or lifestyles of humans and allows for in vivo analysis not possible with human subjects. To accomplish this, cDNA encoding each form of the human β3-subunit was subcloned into an HIV type-1 lentivirus-derived vector under the transcriptional control of the human αIIb gene promoter to direct synthesis of β3 specifically to the megakaryocyte lineage. Bone marrow was isolated from β3-deficient mice and transduced with β3 virions encoding either the PlA1 or PlA2 form of human β3, and then transplanted into lethally irradiated β3-deficient littermates. Flow cytometric analysis demonstrated stable expression of the hybrid murine/human αIIbβ3 integrin complex on the surface of circulating platelets. Immunoanalysis using monoclonal antibodies and human serum that react specifically with the PlA1 or PlA2 confirmed the identity of each alloantigen of human β3. The lentivirus contained a second transgene encoding a drug-selectable marker (P140K MGMT) that was used for in vivo enrichment of transduced cells in mice treated with two regimens of cytotoxic reagents, O6-BG/BCNU. Flow cytometric analysis showed that use of drug-selection resulted in increased expression of the integrin αIIbβ3 complex to equal levels on nearly 100% of platelets using either form of human β3. Similar to platelets from normal mice, platelets expressing each PlA form of β3 could be induced to form aggregates ex vivo upon treatment with a cocktail of physiological agonists of platelet activation (adenosine diphosphate, epinephrine and the thrombin receptor activating peptide).
These results demonstrate the feasibility for targeting expression of altered forms of the human integrin β3-subunit to murine platelets and pave the way for future studies to examine and compare the effect of integrin αIIbβ3 structure on platelet function and thrombosis in vivo.
Platelet Derived Microparticles (PMP) Interfere with Rolling, Adhesion and Transmigration of Hematopoietic Progenitor Cells (HPC).
Authors: Bistrian Roxana , Ruster Brigitte , Gottig Stephan , Seifried Erhard , Henschler Reinhard 
Published: October 2019

Abstract
We wished to investigate if small particles derived from platelet membranes (PMP) which are present in blood may influence the migration behavior of HPC. PMP were isolated from pooled platelet concentrates derived from human whole blood donations via the buffy coat or PRP methods. After activation of platelets with thrombin or calcium ionophore, PMP were quantitatively enriched by sequential centrifugation at 1.250 and 50.000g. Flow cytometric analysis showed separated forward and side scatter profiles of the larger platelets and smaller PMP, with both platelets and PMP staining highly positive for CD41 and CD61. Purity of PMP was 89–92%. Binding of PMP to HPC was performed at 37°C in cell culture medium at ratios between 3 and 100 PMP/HPC. Binding was assessed flow cytometrically using PMP which were fluorescence-marked with PKH26, or by appearance of CD41/CD61 complex on the surface of HPC. We found that PMP dose-dependently bound human KG-1 or primary CD34+ HPC, with half-saturation occurring within seconds to a few minutes, and 10–20 PMPs binding per HPC.
Compared to controls, the binding of PMP-preloaded HPC to immobilized fibronectin showed a mean 10.4-fold reduction with KG-1 cells and a mean 4.2-fold reduction with CD34+ primary HPC. The interaction of PMP-pretreated HPC with endothelial cells (EC) was assessed under laminar shear flow in a parallel plate flow chamber at defined wall shear stresses using TNF-alpha prestimulated human umbilical vein endothelial cells (HUVEC). We found a 1.6-fold (KG-1) and 2.2 fold (CD34+ HPC) reduction in numbers of rolling and subsequently binding cells at shear stresses of 0.1 dyn/cm2, and a 1.5-fold (KG-1) or 1.7-fold (CD34+ HPC) reduction at 2 dyn/cm2 compared to untreated controls. Both binding and rolling of HPC were dependent on P-selectin in this model, as shown by blocking of the interaction of HPC with EC with MoAB AK-4, and the abrogation of this block with PMP-HPC. Finally, SDF-1alpha-induced transmigration of HPC in transwell chemotaxis chambers was reduced > 3-fold after preincubation of HPC with PMP when more than 10–20 PMP were bound per HPC. Taken together, highly purified PMP are able to bind HPC and to modulate their interaction with endothelium. This process is mediated by (i) suppression of P-selectin mediated rolling and adhesion of HPC to endothelium, (ii) suppression of integrin-mediated adhesion of HPC and (iii) suppression of SDF-1alpha mediated transmigration of HPC. PMPs may therefore be part of a physiological mechanism which can modulate the adhesion behaviour of circulating HPC and protect them from recruitment into sites of inflammation or activated coagulation under conditions of postcapillary or venous shear stress.
The Platelet Specific Chemokine Platelet Factor 4 Induces Expression of E-Selectin in an NF-κ B Dependent Manner.
Authors: Sachais Bruce S. , Ma Peihong , Rux Ann H. , Yu Guangyao 
Published: October 2019

Abstract
The involvement of platelets in the pathogenesis of atherosclerosis has recently gained much attention. Platelet factor 4 (PF4) is a platelet specific chemokine released upon platelet activation. PF4 has been localized to atherosclerotic lesions, including macrophages and endothelium. In this report, we demonstrate that E-selectin, an adhesion molecule involved in atherogenesis, is up-regulated in human umbilical vein endothelial cells exposed to PF4. Induction of E-selectin mRNA is time and dose dependent, and requires the presence of cell surface glycosaminoglycans. Surface expression of E-selectin, as measured by flow cytometry, is also increased by PF4. Activation of NF-κB is critical for PF4 induced E-selectin expression, as demonstrated by promoter activation studies and electrophoretic mobility shift assays. In summary, our data demonstrate that PF4 can increase expression of E-selectin by endothelial cells by activation of NF-κB. PF4 induction of endothelial E-selectin expression represents another mechanism by which platelets may participate in atherosclerotic lesion progression. These data also suggest that PF4 may participate in the proinflammatory functions of activated platelets.
Influence of Multimer Size and a Natural Dimorphism on the Activity of Convulxin.
Authors: Kato Kazunobu , Cheli Yann , Furihata Kenichi , Radis-Baptista Gandhi , Kunicki Thomas J. 
Published: October 2019

Abstract
Convulxin (CVX), a C-type lectin derived from the venom of Crotalus durissus terrificus, is a potent activator of human platelets, binding predominantly to platelet glycoprotein (GP) VI, but also to GP Ibα. Native CVX is an octamer composed of four αβ-heterodimers. It has been speculated that multimer size contributes greatly to CVX function, but proof of this hypothesis has not yet been reported. Additionally, two different native sequences have been reported (GenBank protein accession numbers CAA76182 and AAQ11362), one bearing lysine (K), the other glutamic acid (E), at β chain residue 89, but the physiological relevance of this difference is unknown.
In an earlier report, we have described the production of monomeric recombinant CVX (rCVX) heterodimers using the Drosophila S2 system. We now employ this recombinant protein and site-directed mutagenesis to evaluate the influence of multimer size and the substitution βK89E on CVX function.
By flow cytometry, native CVX (αβ)4 and both recombinant forms of CVX (αβ89K and αβ89E) bind to CHO cells expressing human recombinant GPVI (hrGPVI) and to human platelets in whole blood. Surface plasmon resonance (BIAcore) was employed to assess the kinetics of the interaction between hrGPVI and native or recombinant CVX. The calculated equilibrium dissociation constants (KD) were: for rCVX αβ89K, 11.3 x 10−8 M; for rCVX αβ89E, 9 x 10−8 M; and for native CVX (αβ)4, 2.8 x 10−8 M. These results indicate that the affinities of the two rCVX forms for hrGPVI are essentially the same and that the relative affinity of native CVX is about three-fold higher. Next, aggregation of human PRP was used to assess the relative function of the CVX forms. The minimum concentration of native CVX that induces platelet aggregation (70 picomolar) is roughly 400-fold lower than that of either rCVX αβ89K or rCVX αβ89E (each, 29 nanomolar).
Based on these findings, it is apparent that: 1) There is little, if any difference, in the affinity or activity of the two recombinant forms of CVX; 2) the octameric form of native CVX results in roughly a three-fold increase in affinity for GPVI; and 3) this increase in affinity of the octameric form of native CVX cannot account for the substantial increase in its ability to induce platelet aggregation relative to the recombinant forms. These results are consistent with the hypothesis that the ability of native CVX octamer to cluster mobile GPVI molecules within the platelet membrane may be the single most important factor that contributes to the efficiency with which CVX is able to induce signal transduction and platelet activation. Moreover, smaller forms of CVX, such as the rCVX heterodimers, may prove to be efficient inhibitors of platelet activation by native CVX and other GPVI agonists.
Platelet Counts Vary by Ethnicity, Sex, and Age: Analysis of NHANES III Data.
Authors: Segal Jodi B. , Molterno Alison R. 
Published: October 2019

Abstract
Background: The possibility of variation in platelet count by age and genetic background has not been examined. Identification of subpopulations with elevated platelet counts, within what is traditionally considered a normal range, may identify a group with excessive morbidity or mortality. Furthermore, platelet count differences may suggest populations in which genetic polymorphisms in regulatory proteins such as the thrombopoietin receptor influence platelet production. We hypothesized that there were differences in platelet count by ethnicity, sex and age not explained by environmental factors. Objective: To demonstrate differences in mean platelet counts by ethnicity, sex, and age while controlling for variables known to influence platelet count.
Methods and Design: We used data from the National Health, Nutrition and Examination Survey III (NHANES III), which is a multistage probability sample of the United States population with data collected between 1988 and 1994. Using appropriate weighting for the complex sampling design, the geometric mean platelet count was calculated for the total population and the population stratified by ethnicity, sex, and age, while controlling for C-reactive protein, white blood cell count, iron-deficiency, serum folate, markers of alcohol intake, presence of hepatitis B or C antibodies, and diabetes mellitus. Other potential influences, such as medications, were found not to affect the predicted counts and not included in the models.
Results: The lowest mean platelet counts were among whites (259 K/ml [95% C.I. 255–264 K/ml]) and the highest were in non-Hispanic blacks (275 K/ml [95% C.I. 270–280 K/ml]) with Mexican-Americans having intermediate values (266 K/ml [95% C.I. 261–272 K/ml]), when controlled for age and sex. Older men and women of each ethnicity consistently had lower mean platelet counts, with 60–69 years olds having mean counts approximately 7 K/ml lower than young adults (p=0.015) and 70–90 year olds having mean counts 19 K/ml lower than young adults (p<0.001). Even with controlling for iron deficiency, women had significantly higher platelet counts than men (273 K/ml [95% C.I. 269 – 278]) versus 251 K/ml [95% C.I. 245 – 256])
Conclusion: Mean platelet counts differ by ethnicity, sex, and age and these differences are not explained by covariates known to influence platelet count. This suggests that genetic influences on the platelet count are operative. These data also suggest that there may be a hormonal regulation of platelet count. The decline with age may reflect decreased stem cell function with age; alternatively, there may be a survival advantage to having a lower platelet count. Longitudinal studies of platelet count with aging are indicated.
Production of Monoclonal Antibodies Against ADAMTS13 Determining Its Expression in Different Human Tissues.
Authors: Gao Weiqiang , Chow Xiaojun , Bai Xia , Su Jiang , Ruan Changgeng 
Published: October 2019

Abstract
The deficiency of ADAMTS13/von Willebrand factor-cleaving protease in cancer patients, which can lead to the accumulation of ultra-large von Willebrand factor (UL-vWF) in plasma, has been confirmed by several previous reports. Nevertheless, the results of them did not avoid the heterogeneity between different tumors and the reasons accounted for its deficiency still remain to be elucidated. Since ADAMTS13 is mainly synthesized and released from liver and tumors derived from liver often accompanies with metastasis, we have studied the expression levels of ADAMTS13 in patients with primary hepatocarcinoma and in different hepatic cancer cell lines. Firstly, we detected the ADAMTS13 mRNA and protein levels in paired primary cancer tissues and adjacent normal tissues using semi-quantitative reverse transcription PCR (RT-PCR) and immunohistochemistry. It showed that most of the cancer tissues expressed lower ADAMTS13 levels compared with their paired adjacent normal tissues. Significant low expression levels of ADAMTS13 had a close relationship with distal metastasis of hepatocarcinoma, but the abnormal of hepatic function did not have an association with the deficiency of ADAMTS13 expression. Interestingly, most of the patients suffering with hepatitis B and cirrhosis did not show significantly decreased ADAMTS13 levels, and most of the cancer patients with distal metastasis while without hepatitis B and cirrhosis accompanied markedly deficiency of the protease. The hepatocarcinoma cell lines, HepG2 and BEL7702, also expressed lower ADAMTS13 mRNA levels compared with SMMC7721 and a normal hepatic cell line L02. However, when the hepatocarcinoma cell lines were treated with a demethylation drug 5-aza-2′-deoxycytidine, its ADAMTS13 mRNA expression levels elevated with the increase of treatment dosage, especially in HepG 2 (P<0.05). It seems that the deficiency of ADAMTS13 in hepatocarcinoma might be associated with DNA methylation. The data above revealed that the ADAMTS13 expression levels were lower in hepatocarcinoma tissues. Furthermore, the activity of ADAMTS13 was significantly decreased in aged people older than 65 years, and the extent of methylation of genes are closely related with age. Therefore, based on our results, the deficiency of ADAMTS13 in hepatocarcinoma patients might not be caused by the abnormal of hepatic function, but be related to the DNA methylation of the protease.
Treatment of Relapsed Acute Promyelocytic Leukemia by Arsenic-Based Strategies without Hematopoietic Stem Cell Transplantation in Hong Kong: A Seven-Year Experience.
Authors: Au Wing Y. , Chim James C. , Lie Albert K. , Kumana Cyrus R. , Leung Anskar Y. , Tse Eric W. , Ma Shing Y. , Liang Raymond H. , Kwong Yok L. 
Published: October 2019

Abstract
Background: The optimal therapy for relapsed acute promyelocytic leukemia (APL) after arsenic trioxide (As2O3)-induced remission is unclear. Hematopoietic stem cell transplantation (HSCT) is associated with high morbidity and mortality. Moreover, lasting remission is observed in many patients who are not candidates for HSCT, owing to advanced age or lack of donors, implying that HSCT is not mandatory for durable remission. We evaluated our results of an As2O3-based, non-HSCT regimen for patients with relapsed APL.
Materials and methods: Forty-two consecutive patients (18 men, 24 women, median age: 35 years, 12–72) with relapsed (relapse 1, R1=39, R2=3) APL were treated with an-As2O3 based, non-HSCT regimen. The time from last complete remission (CR) was 22 (6–243) months (mo). Initial treatment was As2O3 (10 mg/day) either intravenously (n=16) or orally (n=28) until CR, followed by idarubicin consolidation (6 mg/m2/day x 9). Twenty-five patients received oral-As2O3 maintenance. Post-As2O3 relapses were treated with oral As2O3 + all-trans retinoic acid (ATRA, 45 mg/m2/day) until CR, followed by maintenance (two weeks of ATRA+As2O3 every 2 mo. for 2 years). Post-As2O3/ATRA relapses were treated with oral As2O3+ATRA+ascorbic acid (1g/day) until CR, followed by consolidation/maintenance with the same regimen (2 weeks every 2 mo. for 2 years). Part of the induction and all of the maintenance therapies were given in the outpatient clinic.
Results: Forty-one patients (98%) achieved CR after initial As2O3 treatment. One 72-year old man with XYY syndrome, diabetes and mental retardation died of pneumonia. Thirteen relapses occurred at a median of 15 (6–22) mo. As2O3-maintenance significantly decreased further relapses (3/24 with versus 10/17 without As2O3-maintenance, p=0.003). Two relapses died of cerebral APL before further treatment could be administered. Of eleven patients treated with As2O3+ATRA, 10 achieved CR, 8 of whom have remained in remission (median follow-up: 33 mo.). Two post-As2O3/ATRA relapses achieved CR again with As2O3+ATRA+ascorbic acid, and have remained in remission after maintenance treatment with As2O3+ATRA+ascorbic acid. All patients in continuous remission (n=38) were PML/RARa negative on polymerase chain reaction (sensitivity 10−3 to 10−4).
Conclusion: Our regimen resulted in a leukemia-free-survival of 89.3%. The results suggest that an oral and mainly outpatient As2O3-based, non-HSCT strategy is efficacious for relapsed APL. In terms of survival, costs, treatment side effects and patient tolerance, the results appear to be comparable to, if not more favorable than, other treatment options based on high dose chemotherapy, graft-versus-leukemia effect, or anti-myeloid antibody therapy.
Association Analysis of Interleukin-1 Gene Cluster Polymorphisms with Ischemic Stroke in a Chinese Population.
Authors: Lai Jiangtao , Pan Jiaqi , Hua Baolai , Zhu Yicheng , Cui Liying 
Published: October 2019

Abstract
Chronic inflammatory process acted an important role in atherothrombosis. Interleukin-1 (IL-1) is one of the key modulators of the inflammatory response, and its activity is critically regulated by its receptor antagonist (IL-1ra). Recently, several interleukin-1 cluster gene polymorphisms may associated with acute coronary syndrome have been reported, although with contrasting results. The associations of a variable number tandem repeat (86bp) polymorphism in intron 2 of IL-1ra and of the -511C/T polymorphism of IL-1β with the risk of the ischemic stroke were studied. 112 ischemic stroke patients of Chinese ancestry studied within ten days after presentation were compared with 95 ethnically matched healthy volunteers. 56 among these 112 stroke patients were followed for six months to have prognosis evaluated through measuring Modified Rankin Scale (RS) and Barthel Index (BI). 60 stroke patients had measured the plasma IL-1ra and C-reative protein (CRP) values. The frequency of the IL-1RN 1/1 genotype in the 112 stroke patients was significantly higher than those in healthy volunteers (93.7% vs 82.1%, p<0.05). The frequency of the IL-1RN allele 1 in the 112 stroke patients was significantly higher than those in healthy volunteers (96.4% vs 90.5%, p<0.01, OR=3.23, 95% CI 1.32–7.91). No significant association was seen for the IL-1β-511 C/T polymorphism. In the six months followed group, IL-1RN1/2 genotype carriers had higher BI scores compared with IL-1RN1/1 genotype carriers (98.00 vs 84.80, p<0.01), and patients with lower plasma IL-1ra value (below the median value 186.55pg/ml) had higher BI scores (95.00 vs 77.19, p<0.05), but no significant influence of CRP values and IL-1ra on prognosis or showed no significantly association on plasma IL-1ra and CRP values with IL-1β-511 C/T or IL-1RN genotpye studied in stroke patients. Our results implicate the IL-1ra gene in the susceptibility to ischemic stroke, which may be a useful clue for pharmacological intervention in IL-1 production.