The effects of PTH,loading and surgical insult on cancellous bone at the bone–implant interface in the rabbit

Enhancing the quantity and quality of cancellous bone with anabolic pharmacologic agents may lead to more successful outcomes of non-cemented joint replacements. Using a novel rabbit model of cancellous bone loading, we examined two specific questions regarding bone formation at the bone–implant interface: (1) does the administration of intermittent PTH, a potent anabolic agent, and mechanical loading individually and combined enhance the peri-implant cancellous bone volume fraction; and, (2) does surgical trauma enhance the anabolic effect of PTH on peri-implant bone volume fraction. In this model, PTH enhanced peri-implant bone volume fraction by 30% in loaded bone, while mechanical loading alone increased bone volume fraction modestly (+ 10%). Combined mechanical loading and PTH treatment had no synergistic effect on any cancellous parameters. However, a strong combined effect was found in bone volume fraction with combined surgery and PTH treatment (+ 34%) compared to intact control limbs. Adaptive changes in the cancellous bone tissue included increased ultimate stress and enhanced remodeling activity. The number of proliferative osteoblasts increased as did their expression of pro-collagen 1 and PTH receptor 1, and the number of TRAP positive osteoclasts also increased. In summary, both loading and intermittent PTH treatment enhanced peri-implant bone volume, and surgery and PTH treatment had a strong combined effect. This finding is of clinical importance since enhancing early osseointegration in the post-surgical period has numerous potential benefits.     

A systematic review of studies of depression prevalence in university students

Background

Depression is a common health problem, ranking third after cardiac and respiratory diseases as a major cause of disability. There is evidence to suggest that university students are at higher risk of depression, despite being a socially advantaged population, but the reported rates have shown wide variability across settings.

Purpose

To explore the prevalence of depression in university students.

Method

PubMed, PsycINFO, BioMed Central and Medline were searched to identify studies published between 1990 and 2010 reporting on depression prevalence among university students. Searches used a combination of the terms depression, depressive symptoms, depressive disorders, prevalence, university students, college students, undergraduate students, adolescents and/or young adults. Studies were evaluated with a quality rating.

Results

Twenty-four articles were identified that met the inclusion and exclusion criteria. Reported prevalence rates ranged from 10% to 85% with a weighted mean prevalence of 30.6%.

Conclusions

The results suggest that university students experience rates of depression that are substantially higher than those found in the general population. Study quality has not improved since 1990.     

Lithium usage and renal function testing in a large UK community population; a case–control study

Objective

This study investigates the prevalence of lithium use, monitoring practice and associated effects on renal function in a large UK community sample.

Method

A large population-based renal function database was cross-referenced with a general practitioner database of 404,673 patients. The renal function of patients prescribed lithium during the 2-year period was compared with that of matched controls. The renal monitoring patterns of these cases were investigated in a naturalistic observational study. Data underwent parametric testing — continuous variables by analysis of variance, with appropriate adjustment, and categorical outcomes by χ² testing. Block analysis of variance was undertaken on case–control data.

Results

A total of 422 patients in the database were prescribed lithium. Renal function monitoring in accordance with published guidelines occurred in 69% of patients. Patients taking lithium had a significantly higher serum creatinine (5.8 μmol/L, P< .001) and lower glomerular filtration rate (5.9 ml/min, P< .001) when compared to matched controls.

Conclusions

This is the first study carried out in a large community sample. Lithium remains widely prescribed in the community setting. The study confirms that lithium has a statistically and clinically significant negative effect on renal function. Despite published guidelines and recognition of the importance of serial measurements, monitoring of renal function is inconsistent.     

Emotion perception and executive functioning predict work status in euthymic bipolar disorder

Functional recovery, including return to work, in Bipolar Disorder (BD) lags behind clinical recovery and may be incomplete when acute mood symptoms have subsided. We examined impact of cognition on work status and underemployment in a sample of 156 Euthymic-BD and 143 controls (HC) who were divided into working/not working groups. Clinical, health, social support, and personality data were collected, and eight cognitive factors were derived from a battery of neuropsychological tests. The HC groups outperformed the BD groups on seven of eight cognitive factors. The working-BD group outperformed the not working-BD group on 4 cognitive factors composed of tasks of emotion processing and executive functioning including processing speed and set shifting. Emotion processing and executive tasks were predictive of BD unemployment, after accounting for number of mood episodes. Four cognitive factors accounted for a significant amount of the variance in work status among the BD participants. Results indicate that patients with BD who are unemployed/unable to work exhibit greater difficulties processing emotional information and on executive tasks that comprise a set shifting or interference resolution component as compared to those who are employed, independent of other factors. These cognitive and affective factors are suggested as targets for treatment and/or accommodations.     

Alternative grafts in anterior cervical fusion

Objective

The present retrospective study was conducted to compare the clinical and radiographic outcomes in patients undergoing anterior cervical discectomy with fusion (ACDF) using carbon fiber reinforced polymer (CFRP) cages, or allograft.

Methods

We retrospectively reviewed cases of ACDF using allograft in 20 patients, and CFRP in 19 who had sequential radiographs before and after surgery, and at 1 year.

Results

There were no apparent significant differences between the 2 groups in age (p = 0.057), gender (p = 0.635), or complications (p = 0.648). At 12 months, there were no cases of construct failure, and fusion appeared to have been achieved in patients of both groups. Lordosis was increased significantly in both groups after surgery (p < 0.001 in allograft and p = 0.025 in CFRP), and was maintained up until 1 year (p < 0.018 in allograft and p = 0.05 in CFRP) without a difference between groups (p = 0.721). Anterior interbody height was significantly increased (p < 0.001 in both groups at each time points) after surgery, without a significant difference between groups (p > 0.21). This increase in height was greatest in magnitude immediately after surgery, and declined with the passage of time. There was no detectable health-related quality of life difference between allograft and CFRP group after surgery (p > 0.05).

Conclusion

The present study demonstrates that CFRP cages appear to have comparable fusion rates, restoration of lordosis and disc space height, and complication rates to patients who undergo ACDF with allograft.     

Dopaminergic Function in the Psychosis Spectrum: An [18F]-DOPA Imaging Study in Healthy Individuals With Auditory Hallucinations

Background: The psychosis phenotype appears to exist in the population as a continuum, but it is not clear if subclinical psychotic symptoms and psychotic disorders share the same neurobiology. We investigated whether the dopaminergic dysfunction seen in psychotic disorders is also present in healthy, well-functioning people with hallucinations. Methods: We compared dopamine synthesis capacity (using 6-[¹⁸F]fluoro-L-DOPA [[¹⁸F]-DOPA] positron emission tomography imaging) in 16 healthy individuals with frequent persistent auditory verbal hallucinations (hallucinating group) with that in 16 matched controls. Results: There was no significant difference in dopamine synthesis capacity in the striatum, or its functional subdivisions, between groups and no relationship between subclinical psychotic symptom severity or schizotypal traits and dopamine synthesis capacity in the hallucinating group. Conclusions: Altered dopamine synthesis capacity is unlikely to underlie subclinical hallucinations, suggesting that although there may be a phenomenological psychosis continuum, there are distinctions at the neurobiological level.     

Short‐term environmental enrichment,in the absence of exercise,improves memory,and increases NGF concentration,early neuronal survival,and synaptogenesis in the dentate gyrus in a time‐dependent manner

Environmental manipulations can enhance neuroplasticity in the brain, with enrichment‐induced cognitive improvements being linked to increased expression of growth factors, such as neurotrophins, and enhanced hippocampal neurogenesis. There is, however, a great deal of variation in environmental enrichment protocols used in the literature, making it difficult to assess the role of particular aspects of enrichment upon memory and the underlying associated mechanisms. This study sought to evaluate the efficacy of environmental enrichment, in the absence of exercise, as a cognitive enhancer and assess the role of Nerve Growth Factor (NGF), neurogenesis and synaptogenesis in this process. We report that rats housed in an enriched environment for 3 and 6 weeks (wk) displayed improved recognition memory, while rats enriched for 6 wk also displayed improved spatial and working memory. Neurochemical analyses revealed significant increases in NGF concentration and subgranular progenitor cell survival (as measured by BrdU+ nuclei) in the dentate gyrus of rats enriched for 6 wk, suggesting that these cellular changes may mediate the enrichment‐induced memory improvements. Further analysis revealed a significant positive correlation between recognition task performance and BrdU+ nuclei. In addition, rats enriched for 6 wk showed a significant increase in expression of synaptophysin and synapsin I in the dentate gyrus, indicating that environmental enrichment can increase synaptogenesis. These data indicate a time‐dependent cognitive‐enhancing effect of environmental enrichment that is independent of physical activity. These data also support a role for increased concentration of NGF in dentate gyrus, synaptogenesis, and neurogenesis in mediating this effect. © 2013 Wiley Periodicals, Inc.