The aim of the present in vitro study was to evaluate the influence of different bone substitute materials (BSM) on the viability of human primary osteoblasts (PO), bone marrow mesenchymal cells (BMMC), and nonadherent myelomonocytic cells (U937). Six different bone substitute materials were tested: Bio-Oss Spongiosa (BOS), Tutodent Chips (TC), PepGen P-15 (P-15), Ostim (OM), BioBase (BB), and Cerasorb (CER). Cells were cultivated on comparable volumes of BSM in 96-well plates. Cell culture-treated polystyrol (Nunclon Delta surface; C) served as positive control. After 2 h and 3, 6, 10, and 14 days, viability of cells was evaluated using a standardized ATP viability assay (CellTiter Glo). Nonsurface-dependent effects of the materials were separately tested using nonadherent U937 suspension cells. For statistical analysis, the Mann-Whitney test was used. Results were considered statistically significant at P < 0.05. Cell viability of PO increased significantly on TC, C, and CER followed by BB. No changes were found for P-15 and decreasing viability for BOS and OM. BMMC showed similar results on C, TC, CER, and P-15. Lower viability for BB and no viability could be detected for BOS and OM (Mann-Whitney test, respectively). Nonadherent cells displayed increasing viability in presence of CER, BB, and BOS. No changes were observed for TC and P-15, whereas for OM, no viability was detected after a maximum cultivation period of 3 days. It was concluded that granular hydroxyapatite (HA; TC, BOS, P-15) and alpha- and beta-tricalciumphosphate (CER, BB) support, whereas nanosized HA (OM) limit or even inhibit surface- and nonsurface-related cell viability in the in vitro model used.

BackgroundAround 30% of the population will experience herpes zoster (HZ), 10% of whom develop postherpetic neuralgia (PHN). Together, these illnesses produce a significant economic burden to the healthcare system.MethodsAdministrative healthcare data collected over the period of April 1st 1997 to March 31st 2014 were analyzed to determine the healthcare system burden of HZ using direct medical costs. Episodes of HZ were identified using international classification of disease (ICD) codes. Trends in age-adjusted (AA) HZ-rates were analyzed by piecewise-regression. Total annual and per-episode costs were determined for drug treatment, medical care, and hospitalizations within each year.ResultsThe incidence of HZ increased by 49.5% from 1997/98 to 2013/14. Piecewise-regression of AA-rates revealed a steady AA-rate of 4.7 episodes/1000 person-years (PY) from 1997/98 to a breakpoint in 2008/09, after which rates began to increase reaching 5.7 episodes/1000 PY in 2013/14.Drug costs rose significantly (p <0.03) from $89.77/episode (95% CI: $82.96, $96.59) to $127.34/episode (95% CI: $117.24, $137.44). Medical costs increased (p <0.0001) from $57.98/episode (95% CI; $55.26, $60.70) to $78.84/episode (95% CI; $74.08, $83.61). Hospitalization rates declined from 3.10% in 1997/98 to 1.36% in 2011/12, resulting in cost dropping from $397/episode (95% CI; $284, $511) to $195/episode (95% CI; $129, $260).Total annual costs of HZ and PHN were $1,997,183 in 2011/12, 4.7% lower than the 1997/98 costs of $2,095,633.ConclusionA significant increase in annual number of HZ cases was observed, driven largely by demographic factors. A 21% increase in the AA-incidence reveals changes in HZ rates beyond those expected by population shifts.The large increase in incidence of HZ, with rising per episode medical and prescription costs were offset by dramatic drops in hospitalization rates, the net effect of which has been to hold the total costs relatively constant. However, the decrease in hospitalization rates slowed over the last half of the study, settling at 1.3% in the last 4 study years. The likely future of HZ burden is one of rising costs, primarily driven by the demographic shifts of an increasing and aging population.

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