Influence of visual feedback sampling on obstacle crossing behavior in people with Parkinson's disease

The purpose of the current study was to investigate the role of visual information on gait control in people with Parkinson's disease as they crossed over obstacles. Twelve healthy individuals, and 12 patients with mild to moderate Parkinson's disease, walked at their preferred speeds along a walkway and stepped over obstacles of varying heights (ankle height or half-knee height), under three visual sampling conditions: dynamic (normal lighting), static (static visual samples, similar to stroboscopic lighting), and voluntary visual sampling. Subjects wore liquid crystal glasses for visual manipulation. In the static visual sampling condition only, the patients with Parkinson's disease made contact with the obstacle more often than did the control subjects. In the successful trials, the patients increased their crossing step width in the static visual sampling condition as compared to the dynamic and voluntary visual sampling conditions; the control group maintained the same step width for all visual sampling conditions. The patients showed lower horizontal mean velocity values during obstacle crossing than did the controls. The patients with Parkinson's disease were more dependent on optic flow information for successful task and postural stability than were the control subjects. Bradykinesia influenced obstacle crossing in the patients with Parkinson's disease.     

Impact of cardiovascular risk factors on vessel wall inflammation and calcified plaque burden differs across vascular beds: a PET-CT study

To evaluate the effect of age, gender and cardiovascular risk factors on vessel wall inflammation and the calcified plaque burden in different vascular beds as assessed by PET/CT. 315 patients (mean age: 57.8 years, 123 male and 192 female) who underwent whole body 18F-FDG PET/CT examinations were included in the study. Blood pool-corrected standardised uptake value (TBR) and the calcified plaque score (CPS, grade 0–4) were determined in the thoracic and abdominal aorta, both common carotid and both iliac arteries. The following cardiovascular risk factors were documented: Age ≥65 years (n = 114), male gender (n = 123), diabetes (n = 15), hyperlipidemia (n = 62), hypertension (n = 76), body mass index (BMI) ≥ 30 (n = 38), current smoker (n = 32). Effects of risk factors on TBR and CPS in different arterial beds were assessed using multivariate regression analysis. In the thoracic aorta TBR was independently associated with age ≥65 years and male gender, CPS was independently associated with age ≥65 years, male gender, hypertension and diabetes. In the abdominal aorta, TBR was independently associated with age ≥65 years and male gender, CPS with age ≥65 years, diabetes and smoking. Independent associations in the carotid arteries were found for age ≥65 years, male gender and BMI ≥ 30 in TBR and for age ≥65 and diabetes in CPS. In the iliac arteries, TBR was independently associated with age ≥65 and CPS with age ≥65, male gender, hypertension, diabetes and smoking. Findings of this PET/CT study demonstrate that the impact of cardiovascular risk factors on vessel wall inflammation and calcified plaque burden differs across vascular territories. Overall, CPS was more closely associated with cardiovascular risk factors compared to TBR.     

Human spleen cell generation of factors stimulating human pluripotent stem cell, erythroid, and myeloid progenitor cell growth

Mitogen-stimulated murine spleen cells produce humoral substances capable of supporting murine hematopoiesis and pluripotent stem cell proliferation in vitro. Thus, we evaluated conditioned media generated by human spleen cells (SCM) in the presence or absence of mitogens for factors stimulatory for human pluripotent (CFU-GEMM), erythroid (BFU- E), and myeloid (CFU-GM) precursors. Two and one half percent to 10% SCM stimulated proliferation of all three types of precursor cells from nonadherent buoyant human marrow target cells. Mitogen-stimulated SCM augmented CFU-GM (175% to 225%), whereas CFU-GEMM and BFU-E growth was essentially unchanged. Cell separation procedures used to determine which cells provided these microenvironmental stimuli indicated that nonadherent mononuclear spleen cells provided the bulk of the CSF-GM, whereas adherent cells (95% nonspecific esterase + monocyte- macrophages) and nonadherent cells provided similar proportions of CSF- mix and erythroid burst-promoting activity (BPA). The nonadherent cells generating high levels of CSF-mix, BPA, and CSF-GM were predominantly Leu-1-negative, ie, non-T, cells. In the presence or absence of mitogens, SCM was a more potent source (1.3- to 3.8-fold) than peripheral leukocyte CM of the growth factors for the three progenitor cell types. Specific in situ cytochemical stains for analyzing morphology of myeloid colonies demonstrated that SCM stimulated the proliferation of the same types and proportions of colonies as human placental CM, suggesting that these CMs may contain similar CSF-GMs. These data show the contribution of spleen cell subsets to the generation of hematopoietic growth factors and the responsiveness of these cells to various mitogenic stimuli.     

Secondary neurologic injury resulting from nonhypotensive hemorrhage combined with mild traumatic brain injury.

Although the emergency physician often treats patients with multiple injuries, there are relatively few clinically relevant models that mimic these situations. To describe the changes after a hemorrhagic insult superimposed on traumatic brain injury (TBI), anesthetized and ventilated juvenile pigs were assigned to 35% hemorrhage (35H), TBI (via fluid percussion); TBI + 35H, and TBI + 40H (40% hemorrhage). Animals were resuscitated with shed blood and crystalloid. Hemodynamic, metabolic, behavioral, and histologic parameters were assessed for 48 h. In TBI, mean arterial pressure (MAP) was not significantly different from baseline. For TBI + 40H, MAP fell by 60% (p < 0.05). This was corrected with resuscitation. Interestingly, TBI + 35H did not show a fall in MAP, while in 35H, MAP was reduced similarly to the TBI + 40H group. ICP was elevated only initially in the TBI group. In TBI + 40H and TBI + 35H, ICP increased markedly with resuscitation, remaining elevated for 60 min. ICP remained at baseline with 35 H. Hemorrhagic focal cerebal contusions at the gray-white interface were observed in 3/5 of TBI + 40H and 5/7 of TBI + 35H. Despite the presence of subarachnoid hemorrhage (SAH) in all the animals in the TBI alone group, none of these animals demonstrated grossly discernible intraparenchymal injury. There was no evidence of intracranial injury in the 35H group. Only in animals receiving a secondary insult of hemorrhage following the primary TBI were cerebral contusions found. These experiments demonstrate the evolution of cerebral contusions as a form of secondary neurologic injury following resuscitation from traumatic brain injury and hemorrhage, even in the absence of significant blood pressure changes.     

Motor imagery of hand actions: Decoding the content of motor imagery from brain activity in frontal and parietal motor areas

How motor maps are organized while imagining actions is an intensely debated issue. It is particularly unclear whether motor imagery relies on action‐specific representations in premotor and posterior parietal cortices. This study tackled this issue by attempting to decode the content of motor imagery from spatial patterns of Blood Oxygen Level Dependent (BOLD) signals recorded in the frontoparietal motor imagery network. During fMRI‐scanning, 20 right‐handed volunteers worked on three experimental conditions and one baseline condition. In the experimental conditions, they had to imagine three different types of right‐hand actions: an aiming movement, an extension–flexion movement, and a squeezing movement. The identity of imagined actions was decoded from the spatial patterns of BOLD signals they evoked in premotor and posterior parietal cortices using multivoxel pattern analysis. Results showed that the content of motor imagery (i.e., the action type) could be decoded significantly above chance level from the spatial patterns of BOLD signals in both frontal (PMC, M1) and parietal areas (SPL, IPL, IPS). An exploratory searchlight analysis revealed significant clusters motor‐ and motor‐associated cortices, as well as in visual cortices. Hence, the data provide evidence that patterns of activity within premotor and posterior parietal cortex vary systematically with the specific type of hand action being imagined. Hum Brain Mapp 37:81–93, 2016. © 2015 The Authors. Human Brain Mapping Published by Wiley Periodicals, Inc.     

Functional outcome of arthrodesis of the first metatarsophalangeal joint using parallel screw fixation

BACKGROUND: Arthrodesis of the first metatarsophalangeal (MTP) joint is a reliable procedure for a painful hallux. Most studies focus on the surgical results rather than the functional outcome for the patient. Therefore, we examined the effects of first MTP joint arthrodesis on activities of daily living and recreational activities. METHODS: Fifty-three patients (60 feet) who had isolated arthrodesis of the first (MTP) joint using a parallel screw fixation technique were evaluated for the functional outcome after the surgery to determine the effect of the arthrodesis on the activities of daily living and on recreational sports and exercise. RESULTS: Fusion was achieved in all patients; all but three stated that they would have the surgery again. Postoperative pain scores evaluated using the Visual Analogue Scale indicated effective pain relief. High levels of function were demonstrated in this group of patients. CONCLUSION: Arthrodesis of the first MTP joint is not only a successful surgical technique for relief of pain and correction of deformity but also allows a high level of function in everyday life and in recreational activities.