Point of optimal kinematic error: Improvement of the instantaneous helical pivot method for locating centers of rotation

This paper proposes a variation of the instantaneous helical pivot technique for locating centers of rotation. The point of optimal kinematic error (POKE), which minimizes the velocity at the center of rotation, may be obtained by just adding a weighting factor equal to the square of angular velocity in Woltring?s equation of the pivot of instantaneous helical axes (PIHA). Calculations are simplified with respect to the original method, since it is not necessary to make explicit calculations of the helical axis, and the effect of accidental errors is reduced. The improved performance of this method was validated by simulations based on a functional calibration task for the gleno-humeral joint center. Noisy data caused a systematic dislocation of the calculated center of rotation towards the center of the arm marker cluster. This error in PIHA could even exceed the effect of soft tissue artifacts associated to small and medium deformations, but it was successfully reduced by the POKE estimation.     

The mitochondrial‐derived peptide MOTS‐c: a player in exceptional longevity?

Mitochondrial‐derived peptides (MDP) are encoded by functional short open reading frames in the mitochondrial DNA (mtDNA). These include humanin, and the recently discovered mitochondrial open reading frame of the 12S rRNA‐c (MOTS‐c). Although more research is needed, we suggest that the m.1382A>C polymorphism located in the MOTS‐c encoding mtDNA, which is specific for the Northeast Asian population, may be among the putative biological mechanisms explaining the high longevity of Japanese people.     

Efecto del ejercicio físico sobre las alteraciones cognitivas y el estrés oxidativo en un modelo transgénico APP/PSN1 para la enfermedad de Alzheimer

Introduction

The beneficial effects of physical exercise, in both the treatment and the prevention of several diseases, have been extensively demonstrated. The most common dementia, Alzheimer′s disease (AD), is a disorder in which exercise induces significant improvement at pathophysiopathological and cognitive levels. In the present work, we studied the relationship between physical exercise, oxidative stress, and cognition in the double transgenic mice model (2×Tg) for AD, APP/PSN1. This model is mainly based on the cerebral deposition of amyloid β plaques.

Material and methods

Eighteen ten-month-old mice were divided into four experimental groups: exercised 2×Tg (2×Tg-E) (n=5), rested 2×Tg (2×Tg-R) (n=5), exercised controls (control-E) (n=4) and rested controls (control-R) (n=4). We trained the animals for twelve weeks with a combination of forced exercise (treadmill running three days/week) and spontaneous wheel running. The animals were evaluated with physical and cognitive tests before and after the training period. We analyzed systemic and cortical oxidative damage and the induction of antioxidant enzymes.

Results

The 2×Tg-R mice showed a decrease in their grip strength and VO_2max as they grew older which was prevented by training. The 2×Tg-E group showed better memory than the 2×Tg-R animals. All the trained groups demonstrated greater exploratory capacity and less anxiety than the sedentary animals. Systemic oxidative damage was slightly decreased in the 2×Tg, although we found no difference in the lipoperoxidation and in the induction of the antioxidant defense in cortex between groups.

Conclusions

Physical exercise leads to improvements in the grip strength, VO_2max, cognition, and memory in 2×Tg mice. These improvements are not significantly related to changes in the antioxidant defenses or a reduction in the oxidative damage brought about by exercise.     

KIR gene variability in cutaneous malignant melanoma: influence of KIR2D/HLA-C pairings on disease susceptibility and prognosis

Natural killer and CD8⁺ T cells are believed to be involved in the immune protection against melanoma. Their function may be regulated by a group of receptors defined as killer immunoglobulin-like receptors (KIRs) and their cognate HLA class I ligands. In this study, we analyzed the influence of KIR genes and KIR/HLA-I combinations on melanoma susceptibility and/or prognosis in a Spanish Caucasian population. For this purpose, KIR genotyping by PCR-SSP and HLA-C genotyping by reverse PCR-SSO were performed in 187 melanoma patients and 200 matched controls. We found a significantly low frequency of KIR2DL3 in nodular melanoma (NM) patients (P?=?0.001) and in ulcerated melanoma patients (P?<?0.0001). Similarly, the KIR2DL3/C1 combination was significantly decreased in melanoma patients (P _c?=?0.008) and in patients with sentinel lymph node (SLN) melanoma metastasis (P _c?=?0.002). Multivariate logistic regression models showed that KIR2DL3 behaves as a protective marker for NM and ulcerated melanoma (P?=?0.02, odds ratio (OR)?=?0.14 and P?=?0.04, OR?=?0.28, respectively), whereas the KIR2DL3/C1 pair acts as a protective marker for melanoma (P?=?0.017, OR?=?0.54), particularly superficial spreading melanoma (P?=?0.02, OR?=?0.52), and SLN metastasis (P?=?0.0004, OR?=?0.14). In contrast, the KIR2DL3(?)/C1C2 genotype seems to be correlated with NM and ulceration. We also report that the KIR2DL1(+)/S1(?)/C2C2 genotype is associated with susceptibility to melanoma and SLN metastasis. Altogether, the study of KIR2D genes and HLA-C ligands may help in assessing cutaneous melanoma risk and prognosis.