Effect of handedness on fMRI activation in the medial temporal lobe during an auditory verbal memory task

Several studies have shown marked differences in the neural localization of language functions in the brains of left-handed individuals when compared with right-handers. Previous experiments involving functional lateralization have demonstrated cerebral blood flow patterns that differ concordantly with subject handedness while performing language-related tasks. The effect of handedness on function in specific stages of memory processing, however, is a largely unexplored area. We used a paired-associates verbal memory task to elicit activation of neural areas related to declarative memory, examining the hypothesis that there are differences in activation in the medial temporal lobe (MTL) between handedness groups. 15 left-handed and 25 right-handed healthy adults were matched for all major demographic and neuropsychological variables. Functional and structural imaging data were acquired and analyzed for group differences within MTL subregions. Our results show that activation of the MTL during declarative memory processing varies with handedness. While both groups showed activation in left and right MTL subregions, the left-handed group showed a statistically significant increase in the left hippocampus and amygdala during both encoding and recall. No increases in activation were found in the right-handed group. This effect was found in the absence of any differences in performance on the verbal memory task, structural volumetric disparities, or functional asymmetries. This provides evidence of functional differences between left-handers and right-handers, which extends to declarative memory processes.     

p53-dependent integration of telomere and growth factor deprivation signals

Ectopically expressed hTERT enables p16(INK4A)(-) human mammary epithelial cells to proliferate in the absence of growth factors, a finding that has led to the hypothesis that hTERT has growth regulatory properties independent of its role in telomere maintenance. We now show that telomerase can alter the growth properties of cells indirectly through its role in telomere maintenance, without altering growth stimulatory pathways. We find that telomere dysfunction, indicated by 53BP1/phosphorylated histone H2AX foci at chromosome ends, is present in robustly proliferating human mammary epithelial cells long before senescence. These foci correlate with increased levels of active p53. Ectopic expression of hTERT reduces the number of foci and the level of active p53, thereby decreasing sensitivity to growth factor depletion, which independently activates p53. The continuous presence of hTERT is not necessary for this effect, indicating that telomere maintenance, rather than the presence of the enzyme itself, is responsible for the increased ability to proliferate in the absence of growth factors. Our findings provide a previously unrecognized mechanistic explanation for the observation that ectopically expressed hTERT conveys growth advantages to cells, without having to postulate nontelomeric functions for the enzyme.     

Craniofacial vertical bone augmentation: A comparison between 3D printed monolithic monetite blocks and autologous onlay grafts in the rabbit

Onlay autografting is amongst the most predictable techniques for craniofacial vertical bone augmentation, however, complications related to donor site surgery are common and synthetic alternatives to onlay autografts are desirable. Recent studies have shown that the acidic calcium phosphates, brushite and monetite, are osteoconductive, osteoinductive and resorb faster in vivo than hydroxyapatite. Moreover, they can be 3D printed allowing precise host bone–implant conformation. The objectives of this study were to confirm that craniofacial screw fixation of 3D printed monetite blocks was possible and to compare the resulting vertical bone augmentation with autograft. 3D printed monolithic monetite onlay implants were fixed with osteosynthesis screws on the calvarial bone surface of New Zealand rabbits. After 8 weeks, integration between the implant and the calvarial bone surface was observed in all cases. Histomorphometry revealed that 42% of the monetite was resorbed and that the new bone formed within the implant occupied 43% of its volume, sufficient for immediate dental implant placement. Bone tissue within the autologous onlay occupied 60% of the volume. We observed that patterns of regeneration within the implants differed throughout the material and propose that this was due to the anatomy and blood supply pattern in the region. Rapid prototyped monetite being resorbable osteoconductive and osteoinductive would appear to be a promising biomaterial for many bone regeneration strategies.     

Minimally invasive maxillofacial vertical bone augmentation using brushite based cements

An ideal material for maxillofacial vertical bone augmentation procedures should not only be osteoconductive, biocompatible and mechanically strong, but should also be applied using minimally invasive procedures and remain stable with respect to the original bone surfaces. This way, implant exposure and infection might be reduced and good mechanical stability may be achieved. Calcium phosphate cements are proven biocompatible and osteoconductive materials that can be injected using minimally invasive procedures. Among these cements, brushite based cements have the added advantage of being biodegradable in vivo. Therefore, this material has the potential for use in the aforementioned procedures. An in vivo study was performed in rabbits to evaluate the potential use of brushite cements in minimally invasive maxillofacial vertical bone augmentation procedures. In this study, we injected self-setting brushite cements on the subperiosteal bone surface using a minimally invasive tunnelling technique. The cement pastes were stable on the bone surface and hardened soon after they were injected thereby negating the need for additional supports such as membranes or meshes. The animals were sacrificed 8 weeks after the intervention and histological observations revealed signs of successful vertical bone augmentation. Therefore, we have demonstrated a minimally invasive vertical bone augmentation procedure that is an attractive alternative to current surgical procedures in terms of increased simplicity, reduced trauma, and lower cost of surgery.     

An EMG-driven model to estimate muscle forces and joint moments in stroke patients

Individuals following stroke exhibit altered muscle activation and movement patterns. Improving the efficiency of gait can be facilitated by knowing which muscles are affected and how they contribute to the pathological pattern. In this paper we present an electromyographically (EMG) driven musculoskeletal model to estimate muscle forces and joint moments. Subject specific EMG for the primary ankle plantar and dorsiflexor muscles, and joint kinematics during walking for four subjects following stroke were used as inputs to the model to predict ankle joint moments during stance. The model's ability to predict the joint moment was evaluated by comparing the model output with the moment computed using inverse dynamics. The model did predict the ankle moment with acceptable accuracy, exhibiting an average R² value ranging between 0.87 and 0.92, with RMS errors between 9.7% and 14.7%. The values are in line with previous results for healthy subjects, suggesting that EMG-driven modeling in this population of patients is feasible. It is our hope that such models can provide clinical insight into developing more effective rehabilitation therapies and to assess the effects of an intervention.     

Is ureteroscopy first line treatment for pediatric stone disease?

PURPOSE: We report our current outcomes for ureteroscopic management of pediatric stone disease. MATERIALS AND METHODS: We carried out a retrospective review of all ureteroscopic procedures for kidney or ureteral calculi performed between 2001 and 2005. Stone location and size, preoperative and postoperative stenting, intraoperative dilation, use of ureteral access sheath, stone-free rates and complications were noted. RESULTS: A total of 100 patients (58% female, mean age 13.2 years) underwent 115 procedures. Stones were located in the renal pelvis in 6% of patients, upper pole in 10%, mid ureter in 11%, lower pole in 17%, proximal ureter in 19% and distal ureter in 37%. Mean stone size was 8.3 mm (median 7.0), with a mean of 1.5 stones per patient. Preoperative stenting was used in 54% of patients, and a stent was placed postoperatively in 76%. Ureteral coaxial dilators and ureteral access sheaths were used in 70% and 24% of patients, respectively. There were no major intraoperative complications, although 5 patients required stent placement for ureteral perforation or extravasation. One patient had a ureteral stricture requiring ureteral reimplantation. Mean followup was 10.1 months (median 2.6). Stone-free rate was 91% on followup ultrasound, abdominal radiography or computerized tomography. Seven patients required staged ureteroscopic procedures to achieve stone-free status. While the number of percutaneous nephrolithotomy and shock wave lithotripsy cases remained stable, the number of ureteroscopic cases increased 7-fold during this period. CONCLUSIONS: Improved ureteroscopic access to stones throughout the pediatric urinary tract and stone-free rates that are comparable to the adult population have led to the adoption of ureteroscopy as first line therapy in children at our institution.     

Evaluation of perceived usefulness of activity scheduling in an inpatient depression group

Recent studies have documented that inpatient care on acute psychiatric wards is ineffective. Government directives suggest that wards should initiate and provide a choice of therapeutic and recreational activities. Priority should be given to effective treatments, such as cognitive behavioural therapy. Homework tasks, such as activity scheduling (AS), form an important part of cognitive behavioural therapy for depression. To address inactivity on the wards and use more evidence-based interventions, a quality improvement project was carried out that implemented AS in an inpatient depression group programme. Both inpatients' and staff's perception of its usefulness was evaluated. Sixteen inpatients completed the Beck Depression Inventory-II, and a questionnaire, which was specifically designed to assess the perceived usefulness of AS. In addition, 14 nursing staff completed a similar questionnaire. Both quantitative and qualitative analyses were carried out. Results showed that all participants found AS useful. Eight inpatients had not engaged in any activity prior to being involved in AS. Most inpatients reported gaining some pleasure and satisfaction out of doing AS and experienced a positive effect on their mood and recovery. While 12 staff expressed interest in learning more about AS, 10 needed more information before carrying it out themselves, and only four had the time to do so. The perceived usefulness of AS will be discussed within the context of a psychiatric inpatient setting.