9 research outputs found
Effects of Hydroxyapatite Particulate Debris on the Production of Cytokines and Proteases in Human Fibroblasts
Cytokines and proteases are secreted by fibroblasts in response to particulate wear debris, and these proteins are felt to play an important role in the development of osteolysis and implant loosening. Although metallic and polyethlyene debris have been studied extensively, little is known about the cellular responses to hydroxyapatite, despite the wide clinical use of these materials. Therefore, the effects of hydroxyapatite (HA) and hydroxyapatite/ÎČâtricalciumphosphate (HA/TCP) on cellular proliferation, cytokine gene expression and protein secretion, protease synthesis, and gelatinolytic activity were investigated in human fibroblasts.
HA and HA/TCP particles were synthesized, and their effects were compared to the responses elicited by titanium and cobalt chromium. Sample characterization by scanning electron microscopy and Coulter Counter demonstrated that the materials had a mean particle size of less than 10 ÎŒm, and all of the particles were compared using the same concentration ranges.
Aliquots of particle suspensions were added to human fibroblasts maintained in tissue culture, and doseâresponse and timeâcourse experiments were performed. Effects of the particles on fibroblast proliferation were assessed, and alterations in cytokine levels were determined by specific enzyme linked immunosorbent assays (ELISA). Cytokines that were evaluated included interâleukinâ1 (ILâÎČ), interleukinâ6 (ILâ6), and tumor necrosis factorâα (TNFâα), all of which have been demonstrated to enhance bone resorption and are associated with osteolysis and implant loosening. Gene expression was determined using Northern blot analysis with cytokineâspecific probes, while secretion of the proteases collagenase and stromelysin was determined by Western blot analysis. Functional gelatinolytic assay was assessed using zymogram gels.
The particles were evaluated in a concentration range from 0.000021 to 0.021 vol%. All of the particles produced increases in cellular proliferation up to 0.0021 vol%, with the largest increases being seen at 0.021 vol% with HA/TCP and titanium. At the highest concentration, both cobalt chromium and HA samples decreased cellular proliferation relative to lower doses, possibly representing cytotoxicity.
Hydroxyapatite particles yielded a 30âfold increase in interleukinâ6 secretion compared to unstimulated controls, which was also greater than three times the levels produced by cobalt chromium, titanium, or HA/TCP. HA particles also tripled the secretion of ILâ1ÎČ at 0.00021 vol%, and doubled TNFâα secretion at 0.021 vol%. Addition of conditioned media prepared by incubation of the particles in culture medium in the absence of cells did not alter the secretion of any of the cytokines. Northern blot analysis using ILâ6 probes also demonstrated strong increases with HA compared to the other materials, suggesting that the action of the HA particles was at the level of transcription. Secretion of the protease collagenase was increased by all of the samples including HA when compared to unstimulated controls. Stromelysin secretion into the culture medium was decreased by cobalt chromium, but increased by titanium, HA, and HA/TCP. All of the particles including HA increased the gelatinolytic activity of the fibroblasts.
These findings demonstrate that HA and HA/TCP particles are capable of stimulating the expression and secretion of cytokines and proteases that enhance bone resorption, and suggest that particulate debris from implants using these coatings may also increase osteolysis and loosening
Heterogeneous stock rats: a new model to study the genetics of renal phenotypes
Chronic kidney disease is a growing medical concern, with an estimated 25.6 million people in the United States exhibiting some degree of kidney injury and/or decline in kidney function. Animal models provide great insight into the study of the genetics of complex diseases. In particular, heterogeneous stock (HS) rats represent a unique genetic resource enabling rapid fine-mapping of complex traits. However, they have not been explored as a model to study renal phenotypes. To evaluate the usefulness of HS rats in the genetics of renal traits, a time course evaluation (weeks 8â40) was performed for several renal phenotypes. As expected, a large degree of variation was seen for most renal traits. By week 24, three (of 40) rats exhibited marked proteinuria that increased gradually until week 40 and ranged from 33.7 to 80.2 mg/24 h. Detailed histological analysis confirmed renal damage in these rats. In addition, several rats consistently exhibited significant hematuria (5/41). Interestingly, these rats were not the same rats that exhibited proteinuria, indicating that susceptibility to different types of kidney injury is likely segregating within the HS population. One HS rat exhibited unilateral renal agenesis (URA), which was accompanied by a significant degree of proteinuria and glomerular and tubulointerstitial injury. The parents of this HS rat were identified and bred further. Additional offspring of this pair were observed to exhibit URA at frequency between 40% and 60%. In summary, these novel data demonstrate that HS rats exhibit variation in proteinuria and other kidney-related traits, confirming that the model harbors susceptibility alleles for kidney injury and providing the basis for further genetic studies
Genetic Variants in Arhgef11 Are Associated With Kidney Injury in the Dahl Salt-Sensitive Rat
A previous genetic analysis comparing the Dahl salt-sensitive (S) rat to the spontaneously hypertensive rat (SHR) identified a major locus on chromosome 2 that influences proteinuria in the S rat. In the present study, blood pressure, proteinuria, and renal hemodynamics were evaluated in congenic strains with small segments of the protective SHR genome on the S background. Proteinuria and renal function were significantly improved in the congenic strains compared to the S. The causative locus interval was narrowed to Arhgef11, Pear1, and Sh2d2 were identified as important candidate genes that may be linked to kidney injury in the S rat. In particular, Arhgef11 plays an important role in the activation of the Rho-ROCK signaling pathway. Inhibition of this pathway using fasudil resulted in a significant reduction of proteinuria in treated S rats (compared to untreated S). However, no difference was observed between treated or untreated SHR or congenic strains. The homologous region in humans was found to be associated with estimated glomerular filtration rate (eGFR) in the Candidate Gene Association Resource (CARe) population. In summary, these findings demonstrate that allelic variants in Arhgef11, acting through the Rho-ROCK pathway, could influence kidney injury in the S as well as provide insight into human kidney disease
Spontaneous Development of Written Literacy
PomÄrnÄ delĆĄĂ dobu sleduji, jak dÄti zachĂĄzejĂ s pĂsmem a jak se mu vÄnujĂ, aĆ„ uĆŸ se jednĂĄ o dÄti pĆedĆĄkolnĂ nebo ĆĄkolou povinnĂ©, aĆ„ uĆŸ je dĂtÄ ve ĆĄkole nebo doma a na ĆĄkolu se pĆipravuje, nebo je mimo ni, v druĆŸinÄ, v zĂĄjmovĂ©m krouĆŸku, na tĂĄboĆe, na ĆĄkole v pĆĂrodÄ, u prarodiÄĆŻ nebo s kamarĂĄdy. Ve vĆĄech tÄchto a mnoha dalĆĄĂch situacĂch se Äasto dÄti v tomto vÄku vÄnujĂ psanĂ zĂĄmÄrnÄ i nezĂĄmÄrnÄ, hrou nebo "pracĂ", tedy ÄinnostĂ, kterĂĄ je podmĂnÄna svĂœm dokonÄenĂm (ĆĄkolnĂ uÄebnĂ lĂĄtka). StĆedem mĂ©ho zĂĄjmu je vztah dĂtÄte ve vĂœvojovĂ©m obdobĂ ĆĄkolnĂ zralosti1 a jeho spontĂĄnnĂho psanĂ jako komunikativnĂ dovednosti ve vztahu k vĂœchovnÄvzdÄlĂĄvacĂmu pĆŻsobenĂ. KomunikativnĂ psanĂ je souÄĂĄstĂ vzdÄlĂĄvacĂ oblasti ÄeskĂœ jazyk a literatura2 a je obsaĆŸeno ve vĆĄech jejich ÄĂĄstech: KomunikaÄnĂ a slohovĂ© vĂœchovÄ, JazykovĂ© vĂœchovÄ i LiterĂĄrnĂ vĂœchovÄ
Increased susceptibility to kidney injury by transfer of genomic segment from SHR onto Dahl S genetic background
MOESM8 of The cohesin-associated protein Wapal is required for proper Polycomb-mediated gene silencing
Additional file 8: Table S1. Genomic sites occupied by Wapal
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Decitabine and vorinostat with FLAG chemotherapy in pediatric relapsed/refractory AML: Report from the therapeutic advances in childhood leukemia and lymphoma (TACL) consortium
Survival outcomes for relapsed/refractory pediatric acute myeloid leukemia (R/R AML) remain dismal. Epigenetic changes can result in gene expression alterations which are thought to contribute to both leukemogenesis and chemotherapy resistance. We report results from a phase I trial with a dose expansion cohort investigating decitabine and vorinostat in combination with fludarabine, cytarabine, and G-CSF (FLAG) in pediatric patients with R/R AML [NCT02412475]. Thirty-seven patients enrolled with a median age at enrollment of 8.4 (range, 1â20) years. There were no dose limiting toxicities among the enrolled patients, including two patients with Down syndrome. The recommended phase 2 dose of decitabine in combination with vorinostat and FLAG was 10âmg/m2. The expanded cohort design allowed for an efficacy evaluation and the overall response rate among 35 evaluable patients was 54% (16 complete response (CR) and 3 complete response with incomplete hematologic recovery (CRi)). Ninety percent of responders achieved minimal residual disease (MRD) negativity (<0.1%) by centralized flow cytometry and 84% (n = 16) successfully proceeded to hematopoietic stem cell transplant. Two-year overall survival was 75.6% [95%CI: 47.3%, 90.1%] for MRD-negative patients vs. 17.9% [95%CI: 4.4%, 38.8%] for those with residual disease (pâ<â.001). Twelve subjects (34%) had known epigenetic alterations with 8 (67%) achieving a CR, 7 (88%) of whom were MRD negative. Correlative pharmacodynamics demonstrated the biologic activity of decitabine and vorinostat and identified specific gene enrichment signatures in nonresponding patients. Overall, this therapy was well-tolerated, biologically active, and effective in pediatric patients with R/R AML, particularly those with epigenetic alterations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/172347/1/ajh26510_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/172347/2/ajh26510.pd
Recommended from our members
Decitabine and vorinostat with FLAG chemotherapy in pediatric relapsed/refractory AML: Report from the therapeutic advances in childhood leukemia and lymphoma (TACL) consortium
Survival outcomes for relapsed/refractory pediatric acute myeloid leukemia (R/R AML) remain dismal. Epigenetic changes can result in gene expression alterations which are thought to contribute to both leukemogenesis and chemotherapy resistance. We report results from a phase I trial with a dose expansion cohort investigating decitabine and vorinostat in combination with fludarabine, cytarabine, and G-CSF (FLAG) in pediatric patients with R/R AML [NCT02412475]. Thirty-seven patients enrolled with a median age at enrollment of 8.4 (range, 1-20) years. There were no dose limiting toxicities among the enrolled patients, including two patients with Down syndrome. The recommended phase 2 dose of decitabine in combination with vorinostat and FLAG was 10âmg/m2 . The expanded cohort design allowed for an efficacy evaluation and the overall response rate among 35 evaluable patients was 54% (16 complete response (CR) and 3 complete response with incomplete hematologic recovery (CRi)). Ninety percent of responders achieved minimal residual disease (MRD) negativity (<0.1%) by centralized flow cytometry and 84% (n = 16) successfully proceeded to hematopoietic stem cell transplant. Two-year overall survival was 75.6% [95%CI: 47.3%, 90.1%] for MRD-negative patients vs. 17.9% [95%CI: 4.4%, 38.8%] for those with residual disease (pâ<â.001). Twelve subjects (34%) had known epigenetic alterations with 8 (67%) achieving a CR, 7 (88%) of whom were MRD negative. Correlative pharmacodynamics demonstrated the biologic activity of decitabine and vorinostat and identified specific gene enrichment signatures in nonresponding patients. Overall, this therapy was well-tolerated, biologically active, and effective in pediatric patients with R/R AML, particularly those with epigenetic alterations