Dysregulated in vitro hematopoiesis, radiosensitivity, proliferation, and osteoblastogenesis with marrow from SAMP6 mice

The senescence accelerated-prone mouse variant 6 (SAMP6) shows normal growth followed by rapid aging, development of osteopenia, and shortened lifespan, compared with control R1 mice. Because oxidative stress is a fundamental mechanism of tissue aging, we tested whether cellular parameters that are associated with oxidative stress are impaired with marrow from SAMP6 mice. We compared in vitro hematopoiesis, irradiation sensitivity, proliferative potential, and osteoblastogenesis with marrow cells from SAMP6 and R1 mice. Marrow cells from SAMP6 mice showed shortened in vitro hematopoiesis; their stromal cells showed greater radiation sensitivity and decreased proliferation. Consistent with those properties, there was constitutive upregulation of transforming growth factor-β(1), an inhibitor of hematopoiesis, and of cell cycle inhibitory genes, p16(INK4A) and p19(ARF). Paradoxically, there was constitutive expression of osteoblast genes in stromal cells from SAMP6 mice, but in vitro matrix mineralization was impaired. These studies and data included in other reports indicate that impaired proliferation of osteoblast progenitors in SAMP6 marrow may be a major factor contributing to accelerated loss of bone mass. In sum, marrow from SAMP6 mice had diminished capacity for long-term hematopoiesis, increased radiosensitivity, and reduced proliferative capacity.     

Comparison of periodontal open flap debridement versus closed debridement with Er,Cr:YSGG laser

Background

Traditional periodontal open flap debridement (OFD) results in reduced pocket depth (PD), clinical attachment loss (CAL), gingival recession (GR) and postoperative pain and discomfort. The quest to overcome these shortcomings has led to research into Er,Cr:YSGG laser assisted pocket therapy (ELAPT). This study was designed to compare the clinical outcomes of ELAPT versus OFD.

Methods

Fifteen patients with a PD of ≥5 mm and ≤8 mm at two sites were selected. Test sites (Group 1) were treated by ELAPT and the control (Group 2) by OFD. Clinical parameters were recorded at baseline, 3 and 6 months and included Plaque Index (PI), Gingival Index (GI), modified Sulcular Bleeding Index (mSBI), PD, CAL and GR.

Results

Both treatments produced a reduction in PI, GI, mSBI and PD, an increase in GR, and a gain in CAL at 3 and 6 months. The mean gain of CAL in Group 1 at 3 and 6 months (1.60 ± 0.78 and 1.80 ± 0.63) was similar (p > 0.05) to the value of Group 2 (1.93 ± 0.88 and 2.00 ± 0.54). GR increased significantly (p < 0.05) only in Group 2 at 3 and 6 months (1.80 ± 0.56 and 1.87 ± 0.64) compared to Group 1 (0.50 ± 0.68 and 0.60 ± 0.74).

Conclusions

ELAPT compared with OFD results in similar CAL gains with less GR and significant reductions in PD, GI and mSBI, and may be considered as an alternative to surgical therapy.     

Clinical risk factors related to failures with zirconia-based restorations: An up to 9-year retrospective study

Objectives

The first objective of this study was to retrospectively evaluate zirconia-based restorations (ZBR). The second was to correlate failures with clinical parameters and to identify and to analyse chipping failures using fractographic analysis.

Methods

147 ZBR (tooth- and implant-supported crowns and fixed partial dentures (FPDs)) were evaluated after a mean observation period of 41.5 ± 31.8 months. Accessorily, zirconia implant abutments (n = 46) were also observed. The technical (USPHS criteria) and the biological outcomes of the ZBR were evaluated. Occlusal risk factors were examined: occlusal relationships, parafunctional habits, and the presence of occlusal nightguard. SEM fractographic analysis was performed using the intra-oral replica technique.

Results

The survival rate of crowns and FPDs was 93.2%, the success rate was 81.63% and the 9-year Kaplan–Meier estimated success rate was 52.66%. The chipping rate was 15% and the framework fracture rate was 2.7%. Most fractographic analyses revealed that veneer fractures originated from occlusal surface roughness. Several parameters were shown to significantly influence veneer fracture: the absence of occlusal nightguard (p = 0.0048), the presence of a ceramic restoration as an antagonist (p = 0.013), the presence of parafunctional activity (p = 0.018), and the presence of implants as support (p = 0.026). The implant abutments success rate was 100%.

Conclusions

The results of the present study confirm that chipping is the first cause of ZBR failure. They also underline the importance of clinical parameters in regards to the explanation of this complex problem. This issue should be considered in future prospective clinical studies.

Clinical significance

Practitioners can reduce chipping failures by taking into account several risk parameters, such as the presence of a ceramic restoration as an antagonist, the presence of parafunctional activity and the presence of implants as support. The use of an occlusal nightguard can also decrease failure rate.     

Rectal Cancer and Teaching Hospitals: Hospital Teaching Status Affects Use of Neoadjuvant Radiation and Survival for Rectal Cancer Patients

Background

For rectal cancer, it is unknown how use of radiation, treatment cost, and survival differ based on hospital teaching designation.

Methods

Private insurance claims data linked with the Pennsylvania Cancer Registry were used to identify rectal cancer patients undergoing surgery from 2004 to 2006. Patients with missing data of interest were excluded. Hospitals were characterized as follows: large (≥200 beds) versus small size (<200 beds), teaching versus nonteaching, and urban versus rural. Logistic regression was used to model the use of neoadjuvant radiotherapy, and Cox proportional hazards models were used to compare cancer-specific survival between hospital types.

Results

A total of 432 patients were analyzed. There was no difference in the distribution of cancer stages among the various hospital types (all p > 0.20). Teaching hospitals were associated with significantly higher utilization of neoadjuvant radiotherapy for stage II and III cancers compared with nonteaching facilities (57 vs. 28 %; p < 0.0001). On multivariate analysis, teaching status was the only hospital designation associated with use of neoadjuvant radiation (p < 0.001); hospital size and rural/urban designation were not significant. Nonteaching hospitals were more likely to use adjuvant radiotherapy for stage II and III disease (13 vs. 30 %; p < 0.01). Teaching hospitals had lower odds of death from rectal cancer when evaluating all stages [hazard ratio (HR) = 0.35; p < 0.0001] with similar costs of inpatient treatment (teaching: US $30,769 versus nonteaching: US $26,892; p = 0.22).

Conclusions

Teaching designation was associated with higher incidence of neoadjuvant radiotherapy for stage II and III disease, with improved cancer-specific survival compared with nonteaching hospitals, and with similar treatment costs.