Whole-brain white matter network reorganization in HIV

The human immunodeficiency virus (HIV) causes an infectious disease with a high viral tropism toward CD4 T-lymphocytes and macrophage. Since the advent of combined antiretroviral therapy (CART), the number of opportunistic infectious disease has diminished, turning HIV into a chronic condition. Nevertheless, HIV-infected patients suffer from several life-long symptoms, including the HIV-associated neurocognitive disorder (HAND), whose biological substrates remain unclear. HAND includes a range of cognitive impairments which have a huge impact on daily patient life. The aim of this study was to examine putative structural brain network changes in HIV-infected patient to test whether diffusion-imaging-related biomarkers could be used to discover and characterize subtle neurological alterations in HIV infection. To this end, we employed multi-shell, multi-tissue constrained spherical deconvolution in conjunction with probabilistic tractography and graph-theoretical analyses. We found several statistically significant effects in both local (right postcentral gyrus, right precuneus, right inferior parietal lobule, right transverse temporal gyrus, right inferior temporal gyrus, right putamen and right pallidum) and global graph-theoretical measures (global clustering coefficient, global efficiency and transitivity). Our study highlights a global and local reorganization of the structural connectome which support the possible application of graph theory to detect subtle alteration of brain regions in HIV patients.Clinical Relevance-Brain measures able to detect subtle alteration in HIV patients could also be used in e.g. evaluating therapeutic responses, hence empowering clinical trials.

Disruption of structural brain networks in Primary Open Angle Glaucoma

Primary open angle glaucoma (POAG) is one of the most common causes of permanent blindness in the world. Recent studies have originated the hypothesis that POAG could be considered as a central nervous system pathology which results in secondary visual involvement. The aim of this study is to assess possible structural whole brain connectivity alterations in POAG by combining multi-shell diffusion weighted imaging, multi-shell multi-tissue probabilistic tractography, graph theoretical measures and a newly designed disruption index, which evaluates the global reorganization of brain networks in group-wise comparisons. We found global differences in structural connectivity between Glaucoma patients and controls, as well as in local graph theoretical measures. These changes extended well beyond the primary visual pathway. Furthermore, group-wise and subject-wise disruption indices were found to be statistically different between glaucoma patients and controls, with a positive slope. Overall, our results support the hypothesis of a whole-brain structural reorganization in glaucoma which is specific to structural connectivity, possibly placing this disease within the recently defined groups of brain disconnection syndrome.

Phlebographic study does not show differences between patients with MS and control subjects

BACKGROUND AND PURPOSE

Hypothetical correlation between chronic cerebrospinal venous insufficiency and MS has gained the attention of patients and the scientific community. Studies performed by echo-color Doppler ultrasonography have shown different results, and it is necessary to use more objective diagnostic techniques. The aim of our study was to evaluate the presence of stenoses affecting azygos veins and internal jugular veins by use of venography in patients with MS.

MATERIALS AND METHODS

We recruited 2 groups of subjects who underwent venography: the study group included 29 patients with MS and the control group included 15 healthy volunteers. The ileo-lumbar plexus, the azygos, and the internal jugular veins were selectively catheterized. We considered any cross-sectional area reduction of the venous lumen >50% to be a significant stenosis. Furthermore, blood pressure was measured in the studied vessels at the stenotic internal jugular veins.

RESULTS

Selective venography showed at least 1 significant venous stenosis in 84% of subjects examined, without significant difference between the study group and the control group. Positive venography chronic cerebrospinal venous insufficiency patterns were found in 50% of all subjects examined, without any significant difference between the 2 groups. The multivariate logistic regression analysis failed to assess any significant association between the presence of a positive venography and MS condition. The difference between the median blood pressure of stenotic and nonstenotic internal jugular veins was not statistically significant (P = .46).

CONCLUSIONS

Our data exclude any direct correlation between chronic cerebrospinal venous insufficiency and MS because venous abnormalities were equally present in both groups.

Molecular Imaging and Magnetic Resonance Imaging in Early Diagnosis of Alzheimer's Disease

Alzheimer's disease (AD), a progressive neurodegenerative disorder, is the most common cause of dementia in the elderly. Magnetic resonance (MR) or computed tomography (CT) imaging is recommended for routine evaluation of dementias. The development of molecular imaging agents and the new techniques of MR for AD are critically important for early diagnosis, neuropathogenesis studies and assessing treatment efficacy in AD. Neuroimaging using nuclear medicine techniques such as SPECT, PET and MR spectroscopy has the potential to characterize the biomarkers for Alzheimer's disease. The present review summarizes the results of radionuclide imaging and MR imaging in AD.

Caspase-3 is dually regulated by apoptogenic factors mitochondrial release and by SAPK/JNK metabolic pathway in leukemic cells exposed to etoposide-ionizing radiation combined treatment

Ionizing radiation induces a series of multiple intracellular events which can lead to activation of caspases, cytoplasmic proteases involved in the occurrence of apoptosis. The response of leukemic cells to ionizing radiation is amplified when they have been pre-treated with the anticancer drug etoposide, therefore the aim of this work has been to establish the lowest etoposide concentration combined with the lowest ionizing radiation dose to obtain the best antineoplastic response. Two leukemic cell lines, HL-60 and Jurkat, employed in this study demonstrated different sensitivities to ionizing radiation and to etoposide treatment, with Jurkat T cells requiring a higher dose (1 microM) to display cell cycle perturbation and apoptotic DNA damage similar to those seen in HL-60. We hypothesize that this kind of response could be mediated by mitochondrial release of apoptogenic factors and by SAPK/JNK metabolic pathway activation, both leading to caspase-3 cleavage. All in all these results provide insight into the sensitivity or resistance of leukemic cells to antineoplastic agents and identify molecular targets for rational therapeutic intervention strategies.

Protein kinase C zeta nuclear translocation mediates the occurrence of radioresistance in friend erythroleukemia cells

Friend erythroleukemia cells require high doses (15 Gy) of ionizing radiation to display a reduced rate of proliferation and an increased number of dead cells. Since ionizing radiation can activate several signaling pathways at the plasma membrane which can lead to the nuclear translocation of a number of proteins, we looked at the intranuclear signaling system activated by Protein Kinases C, being this family of enzymes involved in the regulation of cell growth and death. Our results show an early and dose-dependent increased activity of zeta and epsilon isoforms, although PKC zeta is the only isoform significantly active and translocated into the nuclear compartment upon low (1.5 Gy) and high (15 Gy) radiation doses. These observations are concomitant and consistent with an increase in the anti-apoptotic protein Bcl-2 level upon both radiation doses. Our results point at the involvement of the PKC pathway in the survival response to ionizing radiation of this peculiar cell line, offering PKC zeta for consideration as a possible target of pharmacological treatments aimed at amplifying the effect of such a genotoxic agent.

[Virtual laryngoscopy of neoplastic pharyngeal and laryngeal pathology]

PURPOSE

This study investigated the feasibility and clinical value of high-resolution virtual laryngoscopy (VL) based on helical CT data sets.

MATERIAL AND METHODS

Fifteen patients with neoplastic laryngeal pathology underwent helical CT examination performed with controlled breath. The CT data were downloaded to a workstation equipped with software for three-dimensional rendering (Silicon Graphics O2, Vitrea Visualization 1.2.8). Two radiologists using Fly Through software generated both antegrade and retrograde endoluminal virtual endoscopy navigations of the larynx. The results of the radiological study were compared with conventional endoscopy findings.

RESULTS AND CONCLUSIONS

Virtual laryngoscopy provided the correct diagnosis in 13 of 15 cases. VL is capable of simulating the visual findings of endoscopy in cases of laryngeal tumors and subglottic stenosis. Small and plane tumors of the vocal chords are not adequately visualized. This technique appears to be useful both as biopsy guide during conventional laryngoscopy and as a correct pre-surgery staging, particularly in stenotic tumors.