Formation of Multiple Nitrosamines from the Ozonation of Corresponding Precursor Secondary Amines: Influencing Factors and Transformation Mechanisms

Abstract

Since nitrosamine disinfection by products is highly carcinogenic, they have attracted considerable attention due to their increased presence in ambient waterways and potable water supplies. For the present study, the potential formation of nitrosamines from corresponding precursor secondary amines during ozonation was investigated. The results revealed that five nitrosamines were observed during the ozonation of their corresponding secondary amines. The molar yields initially increased and then decreased with longer contact times and higher ozone doses. These phenomena indicated that ozone not only promoted nitrosamine formation but also degraded the formed nitrosamines. High pH had a positive influence on nitrosamine formation at room temperature. Further, coexisting substances including nitrate, nitrite, humic acid, and tert-butanol inhibited the generation of nitrosamines due to hydroxyl radical (·OH) competition and scavengers, whereas in the presence of hydroxylamine, nitrosamine formation increased considerably without ozone due to its capacity for independent formation between secondary amines and hydroxylamine. Further, the generation of nitrosamines from secondary amines was primarily attributed to O₃ and ·OH oxidation, which was produced through the decomposition of ozone. The transformation pathways were mainly comprised of the indirect routes between the O₃/·OH intermediates. The findings of this study were helpful toward expanding the knowledge of nitrosamine formation during the corresponding precursor secondary amine ozonation process.

http://bit.ly/2SjymkC

Correction to: Cladribine Tablets: A Review in Relapsing MS

The article Cladribine Tablets: A Review in Relapsing MS, written by Emma D. Deeks, was originally published Online First without open access.

http://bit.ly/2sSiaJ1

MRI assessment of hepatocellular carcinoma after locoregional therapy

Abstract

Liver cirrhosis and hepatocellular carcinoma (HCC) constitute one of the major causes of morbidity, mortality, and high health care costs worldwide. Multiple treatment options are available for HCC depending on the clinical status of the patient, size and location of the tumor, and available techniques and expertise. Locoregional treatment options are multiple. The most challenging part is how to assess the treatment response by different imaging modalities, but our scope will be assessing the response to locoregional therapy for HCC by MRI. This will be addressed by conventional MR methods using LI-RADS v2018 and by functional MR using diffusion-weighted imaging, perfusion, and highlighting the value of the novel intravoxel incoherent motion (IVIM).

http://bit.ly/2DGBWNF

Spontaneous bone regeneration after surgical extraction of a horizontally impacted mandibular third molar: a retrospective panoramic radiograph analysis

Abstract

Background

The mandibular third molar (M3) is typically the last permanent tooth to erupt because of insufficient space and thick soft tissues covering its surface. Problems such as alveolar bone loss, development of a periodontal pocket, exposure of cementum, gingival recession, and dental caries can be found in the adjacent second molars (M2) following M3 extraction. The specific aims of the study were to assess the amount and rate of bone regeneration on the distal surface of M2 and to evaluate the aspects of bone regeneration in terms of varying degree of impaction.

Methods

Four series of panoramic radiographic images were obtained from the selected cases, including images from the first visit, immediately after extraction, 6 weeks, and 6 months after extraction. ImageJ software® (NIH, USA) was used to measure linear distance from the region of interest to the distal root of the adjacent M2. Radiographic infrabony defect (RID) values were calculated from the measured radiographic bone height and cementoenamel junction with distortion compensation. Repeated measures of analysis of variance and one-way analysis of variance were conducted to analyze the statistical significant difference between RID and time, and a Spearman correlation test was conducted to assess the relationship between Pederson's difficulty index (DI) and RID.

Results

A large RID (> 6 mm) can be reduced gradually and consistently over time. More than half of the samples recovered nearly to their normal healthy condition (RID ≤ 3 mm) by the 6-month follow-up. DI affected the first 6 weeks of post-extraction period and only showed a significant positive correlation with respect to the difference between baseline and final RID.

Conclusions

Additional treatments on M2 for a minimum of 6 months after an M3 extraction could be recommended. Although DI may affect bone regeneration during the early healing period, further study is required to elucidate any possible factors associated with the healing process. The DI does not cause any long-term adverse effects on bone regeneration after surgical extraction.

http://bit.ly/2HGArTJ

Mid-term follow-up results of calcaneal reconstruction for calcaneal malunion

Abstract

Background

We hypothesized that calcaneal reconstruction can relieve chronic pain due to calcaneal malunion. We report the mid-term follow-up results of calcaneal reconstruction for calcaneal malunion.

Methods

We reviewed the records of 10 male patients (10 ft) who underwent calcaneal reconstruction for calcaneal malunion between January 2009 and July 2014 at the mid-term follow-up. Talocalcaneal height and angle, calcaneal pitch, calcaneal width, Böhler angle, Stephens classification, and Zwipp classification were evaluated by three orthopedic doctors at each visit (pre-reconstruction, post-reconstruction, and at the last follow-up).

Results

The mean follow-up period was 67.1 months (range, 48–101 months). The sites of pain before reconstruction were lateral aspect (4 patients), plantar aspect (3 patients), diffuse pain (2 patients), and anterior aspect (1 patient). There was a significant difference in talocalcaneal height, talocalcaneal angle, calcaneal pitch, calcaneal width, and Böhler angle before and after reconstruction (p < 0.05). There was no significant difference between reconstruction and the last follow-up. Radiological measurement agreement was calculated to be moderate to strong (intraclass correlation coefficient: 0.659–0.988). Mean American Orthopedic Foot & Ankle Society Ankle and Hindfoot score improved from 66.50 ± 9.37 pre-reconstruction to 80.30 ± 8.52 at the last follow-up (p < 0.05). The mean visual analog scale score improved from 8.60 ± 1.43 before reconstruction to 3.40 ± 0.84 at the last follow-up (p < 0.05). Most patients were satisfied with the outcome postoperatively.

Conclusions

Our results showed substantial improvement in the clinical and radiological outcomes after calcaneal reconstruction of calcaneal malunion. This outcome was maintained until the mid-term follow-up. Therefore, calcaneal reconstruction may be a good option for the treatment of chronic pain caused by the malunion of a calcaneal fracture without severe subtalar arthritis. Further prospective studies are needed to test this theory.

Level of Evidence: Level IV, Retrospective Case Series.

http://bit.ly/2B902Ps

What is the evidence to support early supervised exercise therapy after primary total knee replacement? A systematic review and meta-analysis

Abstract

Background

Total knee replacement (TKR) patients participate in early supervised exercise therapy programs, despite a lack of evidence for such programs or the optimal type, duration or frequency to provide the best clinical outcomes. As hospital stay rates decrease worldwide, the first days after joint replacement surgery are of increasing clinical importance. The purpose of this study was to investigate any reported effects of published early exercise therapy following TKR surgery.

Methods

Databases PubMed, CINAHL, Embase, Cochrane, and Pedro were searched up to August 2018 for trials which investigated an early supervised exercise therapy, commencing within 48 h of surgery. Risk of bias was evaluated using a Modified Downs and Black Checklist and meta-analysis of results was conducted using Review Manager (RevMan). Standardised Mean Differences (SMD) or Mean Differences (MD) and 95% confidence intervals were calculated and combined in meta-analyses.

Results

Four studies (323 patients) that used four different interventions were identified, including Modified Quadriceps Setting, Flexion Splinting, Passive Flexion Ranging and a Drop and Dangle Flexion regime. Patients receiving the Drop and Dangle flexion protocol had superior flexion in the first 2 days after TKR and at discharge, the Flexion Splint patients were discharged earlier and had greater flexion at 6-weeks postoperatively, and the Modified Quadriceps Setting group showed greater hamstring and gluteal muscle strength. Results of the methodological quality assessment showed included studies were of moderate quality. The meta-analysis included 3 of the 4 trials and found no significant differences between groups in maximum knee flexion (MD = 1.34; 95% CI, − 5.55–8.24) or knee society scores (MD = − 1.17; 95% CI, − 4.32–1.98) assessed at 6 weeks post-operatively.

Conclusion

The paucity and heterogeneity of existing studies that examine early supervised exercise therapy following TKR surgery makes it challenging for clinicians to deliver high-quality evidence-based exercise programs in the early postoperative period. Although superior knee flexion range was found across differing regimes, the meta-analysis showed no significant difference in this outcome between groups at 6 weeks. The results of this review show high quality randomized clinical trials are urgently needed to evaluate the impact of early exercise following TKR surgery.

Trial Registration

This review was registered with PROSPERO (CRD42017081016).

http://bit.ly/2TjVEEr

Prevalence and potential risk factors of flight-related neck, shoulder and low back pain among helicopter pilots and crewmembers: a questionnaire-based study

Abstract

Background

Flight-related neck, shoulder and low back pain are the most common musculoskeletal disorders among helicopter pilots and their crewmembers, thus becoming a growing concern. Information on the combined prevalence of these types of pain and related risks are scarce. The aim of this study was therefore to estimate pain prevalence and to evaluate potential risk factors for neck pain among helicopter pilots and crewmembers within the armed forces, the airborne police and airborne rescue organizations in Austria.

Methods

Among a cohort of 104 helicopter pilots and 117 crewmembers (69.8% compliance), demographics, flying experience, use of Night Vision Goggles (NVG), helicopter type flown, prevalence and intensity of musculoskeletal symptoms (pain was defined as any reported pain experience, ache or discomfort) were collected by an online-based questionnaire.

Results

For helicopter pilots the 12-month prevalence of neck pain was 67.3%, followed by low back (48.1%) and shoulder pain (43.3%). Among crewmembers, the 12-month pain prevalence were 45.3, 36.8 and 30.8% among the neck, lower back and shoulder, respectively. During this period, 41.8% of these helicopter pilots had experienced 8–30 pain days in the areas of neck (45.7%), shoulder (37.8%) and lower back (42.0%) whereas 47.8% of crewmembers self-reported 1–7 days of neck (54.7%), low back (44.2%) and shoulder (44.4%) pain in the previous year. The 3-month prevalence of neck pain was 64.4% followed by low back (42.3%) and shoulder pain (38.5%) for helicopter pilots. Among crewmembers, 41.9% suffered from neck, 29.9% from low back and 29.1% from shoulder pain the previous 3 months. Multivariate regression analysis revealed NVG use (OR 1.9, 95% CI, 1.06–3.50, p = 0.032), shoulder pain (OR 4.9, 95% CI, 2.48–9.55, p < 0.001) and low back pain (OR 2.3, 95% CI, 1.21–4.31, p = 0.011) to be significantly associated with neck pain.

Conclusions

The 12- and 3-month prevalence of neck, shoulder and low back is considerably high among both, helicopter pilots and crewmembers confirming the existence of this growing concern. The use of NVG devices, shoulder and low back pain in the previous 12 months represent independent risk factors for neck pain. These findings highlight the need for longitudinal studies.

http://bit.ly/2B8ZKYS