Social context modulates behavioural and brain immediate early gene responses to sound in male songbird

Although it is well known that brain sensory information processing is a highly modulated phenomenon, how this brain function is shaped by experience and social context remains a question to explore. In this paper, we present the first attempt to investigate this problem using a songbird acoustic communication paradigm. Social context is well known to influence acoustic communicating behaviours in birds. The present paper investigates whether brain processing of auditory inputs can be modulated by this 'audience effect'. Given that call-based communication is known to be highly context-dependent, we focused on the response of male zebra finches (Taeniopygia guttata) to female calls. We tested to see if the current social context surrounding the hearing bird can modify a sound-induced immediate early gene (IEG) activation in the specific region of the caudomedial nidopallium (NCM), a songbird brain analogous to the superficial layers of the mammalian primary auditory cortex. Our results show that the expression of the sound-induced immediate early gene ZENK in the NCM is considerably enhanced when the hearing bird is in the presence of conspecifics, compared to when he is alone. This context-dependent increase of a sound-induced immediate early gene expression can be correlated with the differential behavioural response of males to the playback of the same acoustic stimulus as a function of social context.     

Oxygen and glucose deprivation induces major dysfunction in the somatosensory cortex of the newborn rat

The mechanisms and functional consequences of ischemia-induced injury during perinatal development are poorly understood. Subplate neurons (SPn) play a central role in early cortical development and a pathophysiological impairment of these neurons may have long-term detrimental effects on cortical function. The acute and long-term consequences of combined oxygen and glucose deprivation (OGD) were investigated in SPn and compared with OGD-induced dysfunction of immature layer V pyramidal cortical neurons (PCn) in somatosensory cortical slices from postnatal day (P)0-4 rats. OGD for 50 min followed by a 10-24-h period of normal oxygenation and glucose supply in vitro or in culture led to pronounced caspase-3-dependent apoptotic cell death in all cortical layers. Whole-cell patch-clamp recordings revealed that the majority of SPn and PCn responded to OGD with an initial long-lasting ischemic hyperpolarization accompanied by a decrease in input resistance (R(in)), followed by an ischemic depolarization (ID). Upon reoxygenation and glucose supply, the recovery of the membrane potential and R(in) was followed by a Na+/K+-ATPase-dependent postischemic hyperpolarization, and in almost half of the investigated SPn and PCn by a postischemic depolarization. Whereas neither a moderate (2.5 mm) nor a high (4.8 mm) increase in extracellular magnesium concentration protected the SPn from OGD-induced dysfunction, blockade of NMDA receptors with MK-801 led to a significant delay and decrease of the ID. Our data demonstrate that OGD induces apoptosis and a profound dysfunction in SPn and PCn, and underline the critical role of NMDA receptors in early ischemia-induced neuronal damage.     

Hemispheric activation and interaction: past activity affects future performance

Previous studies have shown that when hemispheric activation is modulated by a lateralised task performed concurrently with a second task, performance in the second task is affected by the side of the more active hemisphere. This effect is thought to be produced by competition for limited resources required to complete the two tasks and/or by a greater allocation of attention to the hemifield contralateral to the more active hemisphere. Little is known on how task performance is affected by the pattern of activation in the two cerebral hemispheres before a target task is conducted. The present study investigated how manipulation of hemispheric activity influenced performance of a non-lateralised task (letter matching). Greater left hemisphere activity interfered most with performance of the letter- matching task and was more pronounced in the early learning stage. Male participants were most affected by this effect. The results are discussed in relation to hemispheric interaction, functional lateralisation, and allocation of attention.     

Evidence-based management of peripheral vascular disease

Peripheral vascular disease (PVD) is very prevalent in the United States and is part of a global vascular problem. PVD patients have a heightened inflammatory state and are at high risk of death from acute cardiovascular problems rather than from progression of PVD. Modifiable risk factors for PVD include smoking, hypertension, diabetes, hyperlipidemia, elevated high sensitivity C-reactive protein, obesity, and the metabolic syndrome. Symptomatic treatment of claudication includes smoking cessation, exercise, cilostazol, statins, and revascularization with percutaneous or surgical therapy. Antithrombotic therapy with aspirin or clopidogrel is important to reduce cardiovascular events but does not affect symptoms of claudication. Patients with rest limb ischemia or ulceration should be revascularized to minimize the chance of limb loss. Percutaneous revascularization is not without significant complications, however, and future research needs to focus on inflammation, thrombosis, and restenosis in the PVD patient. Finally, new devices that tackle difficult lesions, drug-eluting stents, and pharmacologic agents that reduce global atherosclerosis are on the horizon and are likely to become critical components in the management of the PVD patient.     

How the retinal network reacts to epiretinal stimulation to form the prosthetic visual input to the cortex

We considered the problem of determining how the retinal network may interact with electrical epiretinal stimulation in shaping the spike trains of ON and OFF ganglion cells, and thus the synaptic input to first-stage cortical neurons. To do so, we developed a biophysical model of the retinal network with nine stacked neuronal mosaics. Here, we describe the model's behavior under (i) electrical stimulation of a retina with complete cone photoreceptor loss, but an otherwise intact circuitry and (ii) electrical stimulation of a fully-functional retina. Our results show that electrical stimulation alone results in indiscriminate excitation of ON and OFF ganglion cells and a patchy input to the cortex with islands of excitation among regions of no net excitation. Activation of the retinal network biases the excitation of ON relative to OFF ganglion cells, and in addition, gradually interpolates and focuses the initial, patchy synaptic input to the cortex. As stimulation level increases, the cortical input spreads beyond the area occupied by the electrode contact. Further, at very strong stimulation levels, ganglion cell responses begin to saturate, resulting in a significant distortion in the spatial profile of the cortical input. These findings occur in both the normal and the degenerated retina simulations, but the normal retina exhibits a tighter spatiotemporal response. The complex spatiotemporal dynamics of the prosthetic input to the cortex that are revealed by our model should be addressed by prosthetic image encoders and by studies that simulate prosthetic vision.     

Numbers of Foxp3-expressing CD4+CD25high T cells do not correlate with the establishment of long-term tolerance after allogeneic stem cell transplantation

OBJECTIVE: Regulatory CD4 T cells that express high levels of CD25 play a vital role in the maintenance of tolerance to self antigens and are required for the induction of nonresponsiveness to alloantigens. The long-term CD4+CD25high T-cell reconstitution after allogeneic stem cell transplantation is unknown. Here, we evaluated whether recovery of this T-cell subset might be linked to the establishment of full donor/recipient tolerance. METHODS: The frequency of CD4+CD25high T cells was determined by Fluorescence Activated Cell Sorter (FACS) analysis in 31 patients, with a mean follow-up of more than 31 months posttransplant. The expression levels of Foxp3 mRNA were assessed by quantitative real-time polymerase chain reaction (RT-PCR). RESULTS: Patients with or without graft-versus-host disease (GvHD) had significant and persistent CD4 T-cell lymphopenia. The relative frequency of CD25high cells and the expression levels of FoxP3 mRNA within this subset were similar between all patients and healthy controls. No significant difference was found in the number of Foxp3-expressing CD4+CD25high T cells in patients with or without GvHD. Finally, younger age and absence of previous GvHD were significantly linked to CD4+CD25high T-cell recovery. CONCLUSION: The low number of Foxp3-expressing CD4+CD25high T cells in grafted patients is not a specific default of this compartment but a consequence of global CD4 T-cell lymphopenia after allogeneic stem cell transplantation. Moreover, levels of Foxp3 mRNA in the CD25+ T-cell compartment do not allow predicting the development of GvHD in the long term.     

Exclusive ileal endometriosis

Endometriosis is a common condition, but its exclusive localization on the ileum is very rare. Unless there is catamenial exacerbation of symptoms, and considering the lack of specificity of results, diagnosis can be difficult. We report the case of a 50 year-old woman presenting with chronic pain in the right lower quadrant. Initial explorations revealed an ileal tumor which was not characterized before the occurrence of acute small bowel obstruction. Ileo-caecal resection by laparotomy relieved the symptoms and alllesions were removed. Diagnosis of ileal endometriosis was made by pathological examination of the resected specimen.