Search

Practice-induced visual perceptual learning is thought to reflect the plasticity of sensory brain regions. The hypothesis that changes in early visual areas may depend on top-down modulation from higher level brain regions by attentional mechanisms is still debated. We used a causal approach by repetitive transcranial magnetic stimulation (rTMS) to evaluate the role of primary visual cortex (V1) and posterior parietal cortex (PPC) in visual perceptual learning. Twelve healthy volunteers performed a forced-choice orientation discrimination task of gabor patches (consisting of 500 trials in five blocks) without any intervention or immediately after a conditioning inhibitory 1-Hz rTMS protocol delivered over the V1, the right PPC, and the vertex (control area), in four different days. Conditioning inhibition by 1-Hz rTMS over the V1 produced an overall worsening of the performance accuracy but no effect in the learning rate, as measured by the slope of the learning curve. The learning rate was lower after right PPC inhibition compared to the other conditions, when evaluated during the first two blocks (200 trials) where occurred most of the learning. These preliminary findings suggest that higher level brain regions may be involved in the mechanisms underlying perceptual learning.

Purpose To assess the role and to analyse the time required to perform intra-operative ultrasound (IUS) in neurosurgery. Methods Thirty-two patients with intracranial and spinal cord lesions underwent IUS with a standard, b-mode linear scanner. Results Intra-operative ultrasound resulted in reduction of the amount of potential damage to normal nervous tissues. In four patients, IUS played a fundamental role in the decision to enlarge the surgical exposure before opening the dura. The average length of time spent by the radiologist in the operating room was 1.45h in spinal cases and 1.15h in intracranial cases. Performance and interpretation of the IUS examination generally required one-fifth of the overall time spent by the radiologist in the operating room. Conclusions Intra-operative ultrasound is an easily available tool making the surgical procedures more accurate, even with standard equipment. However, it is both an operator-dependent and a time-consuming activity for the radiologist, and it would be useful for neurosurgeons to be trained to perform it.

From January 1990 to April 1997 we retrospectively evaluated 90 patients with MR examinations at our Spine Unit. The following post-traumatic spinal cord lesions were diagnosed: atrophy (47 pts), myelomalacia (40 pts), cysts (14), syrinx (14) and medullary transection with adhesion(4 pts). MR was very useful to identify atrophy more frequently found at the cervical-thoracic level (C6-D3). Myelomalcia was found in a patient with severe vertebral body trauma with chronic compression of the spinal cord. Intramedullary cysts were found in patients with hematomyelia in acute phase and were stable lesions. Post-traumatic syringomyelia is the most important sequela due to the fact that is often correlated with symptoms. MR not only detected the lesion but also identified intramedullary cavities without new neurological symptoms and guided surgery and follow-up. MR is the examination of choice not only for diagnosis of chronic spinal cord lesions but also to evaluate the possibility of surgical treatment.

A new biphasic system (MB Check, Roche) for isolation of mycobacteria from clinical specimens was evaluated by eight different microbiological laboratories in comparison with methods routinely used in the respective laboratories. Altogether 1125 clinical specimens were processed; pretreatment, if performed, was by a variety of methods. Mycobacteria were recovered from 167 specimens with the biphasic system and 165 specimens with the other methods. The average time required for isolation of Mycobacterium tuberculosis was 22.6 days with the biphasic system and 24.7 days with egg-based media; for other mycobacterial species it was 23.5 versus 20.8 days. The inclusion of a chocolate agar section in the biphasic system facilitated the early detection of contaminants, while the NAP-containing section appeared unable to differentiate Mycobacterium tuberculosis from other mycobacterial species. The biphasic system, which enables recovery of mycobacteria in small laboratories without specialized equipment, is more practical than conventional methods and at least as sensitive.

Flowcytometric analysis on T-cell subpopulations in the blood and cerebrospinal fluid (CSF) of 10 children with mumps meningitis (MM) revealed that the proportion of lymphocytes which bore the gamma delta T-cell receptor for antigen was significantly higher in CSF than in autologous and heterologous blood samples. gamma delta T-cell values in CSF of MM patients were also significantly higher than those calculated in CSF specimens from nine children with non-inflammatory neurological disorders. Whether and how the expanded CSF gamma delta T-lymphocyte subset, either CD8+ or double-negative (CD4-/CD8-), contributes to the eradication of mumps virus infection from the central nervous system represents a central focus of our ongoing research.

The expression levels of CD26 and CD31 surface antigens, two adhesion/activation molecules with helper and suppressor activities, respectively, were found to be significantly higher on human colostral T cells (CD3+) than in autologous peripheral blood samples. These findings provide further phenotypical evidence that immune system T lymphocytes are compartmentalized in the mammary gland late in pregnancy and during lactation. The question of whether these overexpanded T lymphocyte populations in breast milk modulate in situ, either by enhancing or suppressing, the cellular and/or humoral immune response of the suckling infant remains to be answered. Additional studies are, therefore, needed to explore this intriguing field concerning the immunology of the colostrum.

A total of 1292 sera, provided by different USLs (Local Health Centers) in the Marche Region (Italy), was tested by ELISA and Western Blot for the detection of anti-HTLV I/II ad HIV-1 antibodies. It was decided not to follow any particular criterion when collecting the sera, so no protocol of admission was established in advance. Of the 1292 sera tested, 12 were found antibody positive to HTLV I/II, 18 to HIV-1 and 4 to both viruses. Of the seropositives, for HTLV I/II and HIV-1, respectively, 2 and 3 were prisoners; 2 and 4 were IVDAs, 3 and 7 were hematological patients, 3 and 2 were hospitalized subjects (not for hematological disorders), and 2 and 2 were positives belonging to a healthy population group. These data suggest that the viruses may also be spreading among groups other than the high-risk ones (homosexuals, IVDAs, prisoners, blood-transfusion recipients, promiscuous heterosexuals).

The proportion of T lymphocytes, mainly CD4 positive, co-expressing the CD40 ligand (CD40-L) was significantly greater (P = 0.001) in the colostrum of 10 breast-feeding mothers than in either autologous or heterologous blood. This surface glycoprotein is a T cell molecule involved in B cell isotype switching and immunoglobulin production with its natural counter-receptor, CD40, expressed by both adult and infant B lymphocytes. As the T cells of newborn infants fail to express the CD40-L when stimulated in vitro, the in vivo upregulation on milk T lymphocytes may be one of the mechanisms through which the mother transfers immune protection to the suckling infant.