Evaluation of Primary Stability of Self‐Tapping and Non‐Self‐Tapping Dental Implants. A 12‐Week Clinical Study

Purpose: The aim of this study was to investigate the relationship between surgical techniques and implant macro‐design (self‐tapping/non‐self‐tapping) for the optimization of implant stability in the low‐density bone present in the posterior maxilla using resonance frequency analysis (RFA). Materials and Methods: A total of 102 implants were studied. Fifty‐six self‐tapping BlueSkyBredent® (Bredent GmbH&Co.Kg®, Senden, Germany) and 56 non‐self‐tapping Standard Plus Straumann® (Institut Straumann AG®, Waldenburg, Switzerland) were placed in the posterior segment of the maxilla. Implants of both types were placed in sites prepared with either lateral bone‐condensing or with bone‐drilling techniques. Implant stability measurements were performed using RFA immediately after implant placement and weekly during a 12‐week follow‐up period. Results: Both types of implants placed after bone condensing achieved significantly higher stability immediately after surgery, as well as during the entire 12‐week observation period compared with those placed following bone drilling. After bone condensation, there were no significant differences in primary stability or in implant stability after the first week between both implant types. From 2 to 12 postoperative weeks, significantly higher stability was shown by self‐tapping implants. After bone drilling, self‐tapping implants achieved significantly higher stability than non‐self‐tapping implants during the entire follow‐up period. Conclusions: The outcomes of the present study indicate that bone drilling is not an effective technique for improving implant stability and, following this technique, the use of self‐tapping implants is highly recommended. Implant stability optimization in the soft bone can be achieved by lateral bone‐condensing technique, regardless of implant macro‐design.     

Multicenter evaluation of parametric response mapping as an indicator of bronchiolitis obliterans syndrome after hematopoietic stem cell transplantation

Parametric response mapping (PRM) is a novel computed tomography (CT) technology that has shown potential for assessment of bronchiolitis obliterans syndrome (BOS) after hematopoietic stem cell transplantation (HCT). The primary aim of this study was to evaluate whether variations in image acquisition under real‐world conditions affect the PRM measurements of clinically diagnosed BOS. CT scans were obtained retrospectively from 72 HCT recipients with BOS and graft‐versus‐host disease from Fred Hutchinson Cancer Research Center, Karolinska Institute, and the University of Michigan. Whole lung volumetric scans were performed at inspiration and expiration using site‐specific acquisition and reconstruction protocols. PRM and pulmonary function measurements were assessed. Patients with moderately severe BOS at diagnosis (median forced expiratory volume at 1 second [FEV1] 53.5% predicted) had similar characteristics between sites. Variations in site‐specific CT acquisition protocols had a negligible effect on the PRM‐derived small airways disease (SAD), that is, BOS measurements. PRM‐derived SAD was found to correlate with FEV1% predicted and FEV1/ forced vital capacity (R = ?0.236, P = .046; and R = ?0.689, P < .0001, respectively), which suggests that elevated levels in the PRM measurements are primarily affected by BOS airflow obstruction and not CT scan acquisition parameters. Based on these results, PRM may be applied broadly for post‐HCT diagnosis and monitoring of BOS.     

Restoration of upper extremity function after peripheral nerve injuries

These days injuries to the peripheral nerves of the upper extremity that necessitate total or partial lesion are very common in the household and working environment. With regard to the majority of these injuries, not only plastic surgeons or neurosurgeons must have knowledge of their correct treatment, but general surgeons as well. The principles of reconstruction of the peripheral nerves of the upper extremity are described. The authors refer to immediate and delayed nerve repair, free nerve grafting, free vascularised nerve grafting, tendon transfer for a paralyzed hand, pedicled muscle transfer, functioning free muscle transplantation and neurotization.     

Renal-tubule metabolism of ifosfamide to the nephrotoxic chloroacetaldehyde: pharmacokinetic modeling for estimation of intracellular levels

Ifosfamide (IF) improves survival in children with solid tumors but causes a high rate of nephrotoxicity. We hypothesized that this is caused by an oxidative metabolite of IF, chloroacetaldehyde, which is produced locally by the cells of the renal tubule (RT). For this hypothesis to be viable, one must document that chloroacetaldehyde concentrations in the RT cell are consistent with levels shown to cause nephrotoxicity in experimental systems. Using pharmacokinetic modeling of experimental data, we show that the median level of chloroacetaldehyde in RT cells is 80 micromol/L, ranging from 35 to 320 micromol/L. These concentrations are consistent with levels shown experimentally to cause functional and structural RT damage and lends validity to the hypothesis that local renal production of chloroacetaldehyde causes nephrotoxicity.     

Renal ontogeny of ifosfamide nephrotoxicity

Ifosfamide-induced nephrotoxicity adversely affects the health and well-being of children with cancer. We have recently shown age-dependent nephrotoxicity induced by ifosfamide, with younger children (<3 years) substantially more vulnerable. The mechanisms leading to this age-related ifosfamide-induced renal damage have not been identified. Underlying this work is the hypothesis that renal ontogeny is involved in the expression and activity of the cytochrome P450 (CYP) enzymes responsible for IF metabolism to the nephrotoxic chloroacetaldehyde. We evaluated renal CYP3A and 2B22 activity in pigs between the ages of 1 day and adulthood, as well as the metabolism of ifosfamide by renal microsomes to 2- and 3-dechloroethylifosfamide (2-DCEIF and 3-DCEIF, respectively). Kidney CYP3A messenger RNA expression peaked 15 to 60 days (0.7-76 +/- 0.19 CYP3A/actin ratio; P < 0.001). Subsequently, this level decreased to adult values (0.54 - 0.03 CYP3A/actin ratio; P = 0.04). Similarly, we detected an increase in the ifosfamide-metabolism rate between young (18 +/- 2 pmol/mg protein/min) and adult (12.2 +/- 0.17 pmol/mg protein/min) animals (P = 0.002). Ours is the first documentation of ontogeny of renal CYP3A and of renal ifosfamide metabolism. These data suggest that age-dependent ifosfamide nephrotoxicity is, at least in part, due to ontogeny in the production chloroacetaldehyde.