Polymeric-Calcium Phosphate Cement Composites-Material Properties: In Vitro and In Vivo Investigations

New polymeric calcium phosphate cement composites (CPCs) were developed. Cement powder consisting of 60 wt% tetracalcium phosphate, 30 wt% dicalcium phosphate dihydrate, and 10 wt% tricalcium phosphate was combined with either 35% w/w poly methyl vinyl ether maleic acid or polyacrylic acid to obtain CPC-1 and CPC-2. The setting time and compressive and diametral tensile strength of the CPCs were evaluated and compared with that of a commercial hydroxyapatite cement. In vitro cytotoxicity and in vivo biocompatibility of the two CPCs and hydroxyapatite cement were assessed. The setting time of the cements was 5–15 min. CPC-1 and CPC-2 showed significantly higher compressive and diametral strength values compared to hydroxyapatite cement. CPC-1 and CPC-2 were equivalent to Teflon controls after 1 week. CPC-1, CPC-2, and hydroxyapatite cement elicited a moderate to intense inflammatory reaction at 7 days which decreased over time. CPC-1 and CPC-2 show promise for orthopedic applications

Preparation, Physical-Chemical Characterization, and Cytocompatibility of Polymeric Calcium Phosphate Cements

Aim. Physicochemical mechanical and in vitro biological properties of novel formulations of polymeric calcium phosphate cements (CPCs) were investigated. Methods. Monocalcium phosphate, calcium oxide, and synthetic hydroxyapatite were combined with either modified polyacrylic acid, light activated polyalkenoic acid, or polymethyl vinyl ether maleic acid to obtain Types I, II, and III CPCs. Setting time, compressive and diametral strength of CPCs was compared with zinc polycarboxylate cement (control). Specimens were characterized using X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. In vitro cytotoxicity of CPCs and control was assessed. Results. X-ray diffraction analysis showed hydroxyapatite, monetite, and brushite. Acid-base reaction was confirmed by the appearance of stretching peaks in IR spectra of set cements. SEM revealed rod-like crystals and platy crystals. Setting time of cements was 5–12 min. Type III showed significantly higher strength values compared to control. Type III yielded high biocompatibility. Conclusions. Type III CPCs show promise for dental applications

The Impact of COVID-19 Pandemic on Spine Surgeons Worldwide : A One Year Prospective Comparative Study

Study Design: Survey Objective: In March of 2020, an original study by Louie et al investigated the impact of COVID-19 on 902 spine surgeons internationally. Since then, due to varying government responses and public health initiatives to the pandemic, individual countries and regions of the world have been affected differently. Therefore, this follow-up study aimed to assess how the COVID-19 impact on spine surgeons has changed 1 year later. Methods: A repeat, multi-dimensional, 90-item survey written in English was distributed to spine surgeons worldwide via email to the AO Spine membership who agreed to receive surveys. Questions were categorized into the following domains: demographics, COVID-19 observations, preparedness, personal impact, patient care, and future perceptions. Results: Basic respondent demographics, such as gender, age, home demographics, medical comorbidities, practice type, and years since training completion, were similar to those of the original 2020 survey. Significant differences between groups included reasons for COVID testing, opinions of media coverage, hospital unemployment, likelihood to be performing elective surgery, percentage of cases cancelled, percentage of personal income, sick leave, personal time allocation, stress coping mechanisms, and the belief that future guidelines were needed (P<.05). Conclusion: Compared to baseline results collected at the beginning of the COVID-19 pandemic in 2020, significant differences in various domains related to COVID-19 perceptions, hospital preparedness, practice impact, personal impact, and future perceptions have developed. Follow-up assessment of spine surgeons has further indicated that telemedicine and virtual education are mainstays. Such findings may help to inform and manage expectations and responses to any future outbreaks.publishedVersionPeer reviewe

The Impact of COVID-19 Pandemic on Spine Surgeons Worldwide

Study Design: Cross-sectional, international survey. Objectives: The current study addressed the multi-dimensional impact of COVID-19 upon healthcare professionals, particularly spine surgeons, worldwide. Secondly, it aimed to identify geographical variations and similarities. Methods: A multi-dimensional survey was distributed to surgeons worldwide. Questions were categorized into domains: demographics, COVID-19 observations, preparedness, personal impact, patient care, and future perceptions. Results: 902 spine surgeons representing 7 global regions completed the survey. 36.8% reported co-morbidities. Of those that underwent viral testing, 15.8% tested positive for COVID-19, and testing likelihood was region-dependent; however, 7.2% would not disclose their infection to their patients. Family health concerns were greatest stressor globally (76.0%), with anxiety levels moderately high. Loss of income, clinical practice and current surgical management were region-dependent, whereby 50.4% indicated personal-protective-equipment were not adequate. 82.3% envisioned a change in their clinical practice as a result of COVID-19. More than 33% of clinical practice was via telemedicine. Research output and teaching/training impact was similar globally. 96.9% were interested in online medical education. 94.7% expressed a need for formal, international guidelines to manage COVID-19 patients. Conclusions: In this first, international study to assess the impact of COVID-19 on surgeons worldwide, we identified overall/regional variations and infection rate. The study raises awareness of the needs and challenges of surgeons that will serve as the foundation to establish interventions and guidelines to face future public health crises.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Aromatic amino acid stimulated effects on signaling pathways under normoxic vs hypoxic conditions.

<p>Reverse-phase protein array graphs of two sets of BMMSCs grown under normoxic conditions (21% O₂/5% CO₂) and under low O₂ tension (3% O₂/5% CO₂; physiologic hypoxia). When cells were 80% confluent they were treated with Phe, Tyr or Trp (100 µM) in serum-free media for 3 h. The cells were washed twice with PBS and lysis buffer was added to the plates. a-Phe, b-Tyr and c-Trp. Results are expressed as means ± SEM for three independent experiments. *<i>p</i>≤0.05 and # <i>p</i>≤0.01. Percent change of hypoxia over control for Phe was determined as percent change of BMMSCs treated with Phe under hypoxic conditions (3% O₂%) vs. BMMSCs treated with Phe under normoxic conditions (21% O₂) (control = 100%). Both sets of BMMSCs were treated with Phe and grown under different oxygen levels. Same for Tyr and Trp pannels. RPS6: Ribosomal protein s6 (S6_pS240_S244-R-V). CAV1: Caveolin 1 (Caveolin-1-R-V). NDRG1: N-myc downregulated gene (NDRG1_pT346-R-V). AKT1 AKT2 AKT3: protein kinase B (Akt_pT308-R-V). STAT3: Signal transducer and activator of transcription 3 (STAT3_pY705-R-V). CTNNB1: β-catenin (beta-Catenin-R-V). NOTCH1: Notch homolog 1 (Notch1-R-V). MAP2K1: Mitogen activated protein kinase (MEK1-R-V). EIF4EBP1: Eukaryotic initiating factor 4 (4E-BP1_pT37_T46-R-V). MAPK8: c-Jun N-terminal kinases (JNK_pT183_pT185-R-V). LCK: Lymphocyte-specific protein tyrosine kinase (Lck-R-V). CCNE1:Cyclin E1 (Cyclin_E1-M-V). BCl2: B-cell lymphoma 2 (Bcl-2-M-V). PIK3R1: Phosphatidylinositol 3-kinase regulatory subunit alpha (PI3K-p85-R-V). PKC: Protein kinase C (PKC-pan_BetaII_pS660-R-V). C12ORF5: TP53-inducible glycolysis and apoptosis regulator (TIGAR-R-V). PEA15: Phosphoprotein Enriched in Astrocytes 15 (PEA15_pS116-R-V). TGM2: transglutaminase2, C polypeptide, protein-glutamine-gamma-glutamyltransferase(Transglutaminase-M-V).</p

Modulatory effects of calcium on Tryptophan stimulated ERK phosphorylation.

<p>Erk (phospho Erk/Total Erk) assesed by Western blots of BMMSCs grown under normoxic conditions (21% O₂/5% CO₂). When cells were 80% confluent, they were treated with either Trp alone (100 µM) or in combination with either additional extracellular calcium (baseline calcium: 1.2 mM increased to 1.8 mM) or a calcium receptor antagonist (NPS 10 nM) in serum-free media. The cells were washed twice with PBS and lysis buffer was added to the plates. Results are expressed as means ± SEM for at least three independent experiments. *<i>p</i>≤0.05 and # <i>p</i>≤0.01.</p