Search PubMed⌕ Search

Biomedical subjects

G Comi

Publications and source records attributed to G Comi.

At least 145 records · Page 8Linked to original sources
PubMed1999

Lesion load quantification on fast-FLAIR, rapid acquisition relaxation-enhanced, and gradient spin echo brain MRI scans from multiple sclerosis patients.

Previous studies have addressed the issue of the usefullness of fast fluid-attenuated (fast-FLAIR), rapid acquisition relaxation-enhanced (RARE), and gradient spin echo (GRASE) sequences in small groups of patients with multiple sclerosis (MS). The aim of this study was to assess and compare the lesion volumes and the intra-rater reproducibility of such measurements using fast-FLAIR, dual echo RARE, and dual echo GRASE brain scans from a large sample of MS patients. Using a 1.5 Tesla scanner, fast-FLAIR, dual echo RARE, and dual echo GRASE scans (24 axial, 5-mm thick contiguous interleaved slices) of the brain were obtained from 50 MS patients. Total lesion loads (TLL) were assessed twice using a semi-automated local thresholding segmentation technique by the same rater from the scans obtained with the three techniques. Mean TLL were 20.3 mL for fast-FLAIR, 16.6 mL for RARE, and 17.6 mL for GRASE sequences. Mean TLL detected by the three techniques were significantly heterogeneous (p < 0.001); at post-hoc analysis, the mean lesion volume detected on fast-FLAIR images was significantly higher than that on both RARE and GRASE images (p < 0.001) and the mean TLL on GRASE scans was significantly higher than that on RARE scans (p = 0.001). The mean values of intra-observer coefficient of variation for TLL measurements were similar for the three techniques (2.69% for fast-FLAIR, 2.33% for RARE, and 2.65% for GRASE). Our results confirm that fast-FLAIR sequences detect higher lesion volumes than those detected by other magnetic resonance imaging (MRI) sequences with shorter acquisition times. However, the reproducibility of TLL measurements is comparable among fast-FLAIR, RARE, and GRASE. This suggests that when assessing MS disease burden with MRI, the choice of the pulse sequence to be used should be dictated by the clinical setting.

Adult↗
PubMed1999

Method for intracellular magnetic labeling of human mononuclear cells using approved iron contrast agents.

A method for intracellular iron labeling of human mononuclear cells (lymphocytes and monocytes) for magnetic resonance imaging (MRI) using simple incubation of cells with approved MRI iron contrast agents is presented. Labeled cells can be detected by MRI in vitro, and this suggests the possibility that the technique could become a marker for in vivo lymphocyte and monocyte trafficking studies in acute inflammatory lesions such as those in Multiple Sclerosis.

Cell Survival↗
PubMed1999

Repeatability of surface EMG variables during voluntary isometric contractions of the biceps brachii muscle.

The repeatability of initial value and rate of change of mean spectral frequency (MNF), average rectified values (ARV) and muscle fiber conduction velocity (CV) was investigated in the dominant biceps brachii of ten normal subjects during sustained isometric voluntary contractions. Four levels of contraction were studied: 10%, 30%, 50% and 70% of the maximal voluntary contraction level (MVC). Each contraction was repeated three times in each of three different days for a total of nine contractions/level/subject and 90 contractions per level across the ten subjects. Repeatability was investigated using the Intraclass Correlation Coefficient (ICC) and the standard error of the mean (SEM) of the estimates for each subject. Contrary to observations in other muscles, CV estimates appeared to be very repeatable both within and between subjects. CV showed a small but significant increase when contraction force increased from 10% to 50% MVC but no change for further increase of force. As force increased, MNF showed a slight decrease possibly related to a wider spreading of the CV values. The rate of time decrement of MNF and CV increased with the level of contraction. The normalized decrement (% of initial value per second) was in general higher for MNF than for CV and was more repeatable between subjects at 10% MVC than at 70% MVC. A final observation is that a resting time of 5 minutes may not be sufficient after a contraction at 50% or 70% MVC.

Adult↗
PubMed1999

Inter-laboratory validation of an ELISA for the determination of serum anti-ganglioside antibodies.

Anti-ganglioside antibodies are frequently sought in the sera of patients with autoimmune peripheral neuropathy, using an enzyme-linked immunosorbent assay (ELISA) as the principal method for antibody detection. Wide variations in assay performance between laboratories have been reported. In this study, we established a standardized ELISA method between laboratories within the European Inflammatory Neuropathy Cause and Treatment (INCAT) group and determined the inter-laboratory variance in assay performance using both the standardized INCAT method and in-house local methods. As expected, the inter-laboratory variances were greater using local methods than using the standardized method, producing titre estimates which could be 24.8 or 7.6 times larger or smaller, respectively, than the true means for these laboratories. Using the standardized method, the within laboratory measurement error accounted for 41% of the inter-laboratory variation, providing a theoretical upper limit to which technical improvements within laboratories could reduce inter-laboratory variation. These data describe the intrinsic weaknesses within the widely used ganglioside antibody ELISA methods and reinforce the importance of inter-laboratory cooperation within this area. Standardized serological reagents used in this study are available from INCAT members.

Antibodies↗
PubMed1999

Review neuroimaging in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a chronic degenerative disorder of unknown etiology affecting the motor system. Conventional and non-conventional neuroimaging techniques can provide essential help both to increase the confidence in ALS diagnosis and to assess the disease evolution. Signal abnormalities at the level of the motor cortex and the corticospinal tract on conventional T2-weighted magnetic resonance (MR) images are a potentially useful marker of ALS pathology. However, the prognostic value of these conventional MR abnormalities is still hampered by their low pathological specificity. Non-conventional MR techniques with a higher pathological specificity, such as MR spectroscopy, magnetization transfer imaging and diffusion-weighted imaging, seem to have some potential not only for ALS diagnosis, but also for monitoring disease evolution either naturally or when modified by experimental treatments.

Amyotrophic Lateral Sclerosis↗
PubMed1999

EEG coherence in pathological conditions.

Coherence analysis of the electroencephalogram is considered an indicator of functional cortico-cortical connections, which makes it suitable for the neurophysiologic investigation of brain connectivity in normal and pathological conditions. In the clinical environment, coherence analysis has been applied in the study of brain development and in the assessment of diseases potentially involving brain connectivity, such as cortical and subcortical dementia, schizophrenia, and corpus callosum lesions. Whereas coherence decrease, at least for the high-frequency bands, is considered the expression of decreased functional cortico-cortical connections, more work needs to be performed in interpreting coherence increases. A special consideration is also required by technical aspects, such as the recording conditions and the reference used, which may greatly influence the results and need to be accounted for when drawing physiopathological interpretations. At present, whereas coherence analysis resulted successful in differentiating patients groups from the normal population, the specificity of coherence changes in various pathological conditions is questionable at the best. The same limits apply to the diagnostic value of the technique in individual patients.

Age Factors↗
PubMed1999

Interferon beta treatment for multiple sclerosis has a graduated effect on MRI enhancing lesions according to their size and pathology.

OBJECTIVE: The ability of recombinant human interferon beta-1a (rh-IFN beta-1a) to suppress multiple sclerosis activity, evaluated from MRI, was assessed across a range of lesions enhancing at different gadolinium-DTPA (Gd) doses and with different sizes. METHODS: Every 4 weeks, standard dose (Sd; 0.1 mmol/kg Gd) and triple dose (Td; 0.3 mmol/kgGd) MRI were obtained from 18 patients with relapsing-remitting multiple sclerosis for 3 months before and 4 months after starting treatment with 44 microgram rh-IFN beta-1a subcutaneously, once a week. RESULTS: The total numbers of enhancing lesions were 145 and 126 on Sd scans and 278 and 192 on the Td scans obtained before and after treatment. The introduction of treatment decreased, on average, the rate of appearance of new enhancing lesions seen on Sd and Td scans by 37% (p<0.001). Treatment effects on new enhancing lesions seen on Td scans was, on average, 28% higher than on those seen on Sd scans. The distribution of lesion sizes on Td scans changed significantly during the treatment period (p=0.05), due to a marked decrease in the number of small lesions. CONCLUSIONS: The effect of 44 microgram rh-IFN beta-1a in reducing multiple sclerosis disease activity, as monitored by Gd enhanced MRI, is not homogeneous, but graduated according to the pathological characteristics and size of the lesions.

Adult↗
PubMed1999

Peripheral levels of caspase-1 mRNA correlate with disease activity in patients with multiple sclerosis; a preliminary study.

The cysteine protease caspase-1 plays a crucial part in the inflammatory process due to its ability to proteolitically activate proinflammatory cytokine precursors, such as interleukin (IL)-1beta and IL-18. Multiple sclerosis is a chronic inflammatory demyelinating disease of the CNS in which the pathogenic process is mainly orchestrated by proinflammatory cytokines. The role of caspase-1 in multiple sclerosis was evaluated by measuring its mRNA levels in peripheral blood mononuclear cells (PBMCs) from seven patients with relapsing-remitting multiple sclerosis every 15 days over a 1 year period. The recorded levels were compared with clinical and MRI evidence of disease activity. Brain MRI was performed monthly in each patient. Caspase-1 mRNA levels were significantly increased in PBMCs from patients with multiple sclerosis compared with healthy controls (p<0.001). In patients with multiple sclerosis, a twofold to threefold increase of caspase-1 mRNA mean level was found in the week preceding an acute attack (p<0. 05). The magnitude of caspase-1 mRNA increase correlated with the number of new (p=0.01) but not persisting gadolinium enhancing brain MRI lesions. In conclusion, caspase-1 might be involved in the immune mediated process underlying CNS inflammation and might represent a suitable peripheral immunological marker of disease activity in multiple sclerosis.

Adult↗
PubMed1999

Correlation between MRI and short-term clinical activity in multiple sclerosis: comparison between standard- and triple-dose Gd-enhanced MRI.

We assessed the relative sensitivities of standard (SD)- and triple-dose (TD) gadolinium (Gd)-enhanced magnetic resonance imaging (MRI) for detecting enhancing lesions in different phases of multiple sclerosis (MS) disease activity. Ten MS patients were studied with monthly brain MRI scans for a 3-month follow-up (i.e., 4 scans were obtained for each patient with both SD and TD). A total of 11 relapses were recorded and treated with short-term high-dose steroid therapy. Enhancing lesion numbers and volumes were significantly higher for TD vs. SD scans (p < 0.0001). For both Gd doses, the numbers and volumes of lesions were higher during clinical relapses; the differences were statistically significant when comparing the results for scans obtained during and after a relapse. The gain in sensitivity of TD vs. SD scans for enhancing lesion detection was lower during relapses, whilst it was maximum after relapses, although these differences did not reach statistical significance. Our data confirm the potential role of TD MRI for monitoring MS activity, since, with its higher sensitivity, it may detect more subtle blood-brain barrier (BBB) damage. They also suggest that the degree of BBB damage in individual lesions changes during different phases of disease activity.

Adult↗
PubMed1999

Reproducibility of brain MRI lesion volume measurements in multiple sclerosis using a local thresholding technique: effects of formal operator training.

The assessment of lesion load (LL) on brain magnetic resonance imaging (MRI) scans from patients with multiple sclerosis (MS) is widely used to monitor disease evolution, natural or modified by treatments. In this study, we evaluated the effect of formal operator training on the intra- and inter-observer reproducibility of LL measurements obtained by several operators in a setting similar to that of clinical trials. Proton-density (PD)-weighted, unenhanced and enhanced T1-weighted brain MRI scans were obtained from 10 MS patients. Five naive technicians assessed LL on these images, using a semiautomated local thresholding technique for lesion segmentation and marked hardcopies as a reference. Measurements were performed twice before and twice after a 20-hour operator training. Mean intra-observer measurement coefficient of variations (COV) before and after the training were 3.1 and 1.6% for PD-weighted LL, 4.3 and 1.8% for unenhanced T1-weighted LL (p < 0. 001), 4.9 and 2.0% for enhanced T1-weighted LL (p = 0.002). Mean inter-observer COV were significantly reduced after training (from 10.0 to 5.6% for PD-weighted, from 11.0 to 7.3% for unenhanced T1-weighted and from 16.0 to 6.8% for enhanced T1-weighted LL). Our data indicate that LL assessment on serial MRI scans from MS patients performed by technicians, using a local thresholding technique for lesion segmentation, is characterized by low measurement variability which may be significantly improved by a short and cost-effective training.

Brain↗
PubMed1999

Measuring evoked responses in multiple sclerosis.

Evoked potentials (EPs) have been widely utilised in Multiple Sclerosis (MS) patients to demonstrate the involvement of sensory and motor pathways. Their diagnostic value is based on the ability to reveal clinically silent lesions and to objectivate the central nervous system damage in patients who complain frequently of vague and indefinite disturbances which frequently occurs in the early phases of the disease. The advent of magnetic resonance imaging (MRI) techniques has greatly reduced the clinical utilisation of EPs, which is not fully justifiable, as the information provided by EPs are quite different from those provided by MRI. The abnormalities of evoked responses reflect the global damage of the evoked nervous pathway and are significantly correlated with the clinical findings, while the vast majority of MRI lesions are not associated to symptoms and signs. Transversal and longitudinal studies have demonstrated that EP changes in MS are more strictly related to disability than MRI lesion burden. On the contrary, MRI is more sensitive than EPs in revealing the disease activity. Evoked responses modifications observed in MS are not disease-specific; moreover longitudinal studies showed latency and morphology changes of evoked responses not always related to clinical changes. Such a dissociation can be explained both by technical factors and by subclinical disease activity. To reduce the negative impact of technical aspects, only reproducible parameters of the evoked responses should be used to monitor disease evolution and therapeutic interventions.

Brain↗
PubMed1999

Comparison of MS clinical phenotypes using conventional and magnetization transfer MRI.

OBJECTIVE: To identify differences in pathology between the principal clinical phenotypes of MS using conventional and magnetization transfer (MT) MRI. METHODS: T1-weighted and T2-weighted images as well as MT scans were obtained from 20 controls, 21 patients presenting with clinically isolated syndromes suggestive of MS, and 93 MS patients with relapsing-remitting, secondary progressive, benign, or primary progressive course. Metrics considered: hypointense T1 and T2 lesion volumes, average lesion MT ratio, average brain MT ratio, peak height and position from MT histograms. RESULTS: MS patients had lower MT metrics than controls. Patients with clinically isolated syndromes had MT measures similar to controls, whereas primary progressive MS patients had lower histogram peak height with normal peak position. Relapsing-remitting MS patients had lower MT measures, higher T2 lesion load and ratio of hypointense T1 to T2 lesion volumes than patients with clinically isolated syndromes, and lower MT ratio and peak height than benign MS patients. Benign MS patients were similar to controls and patients with clinically isolated syndromes. Secondary progressive MS patients had the lowest MT measures and highest lesion loads. CONCLUSIONS: Pathology in patients with clinically isolated syndromes is confined to modest tissue damage in the lesions seen on T2-weighted scans. Severe damage is important for the later development of disability. However, microscopic damage in normal-appearing white matter may be a major contributor to disability in primary progressive MS.

Adult↗
PubMed1999

Antimicrobial activity of the essential oils of Thymus vulgaris L. measured using a bioimpedometric method.

The essential oils obtained from Thymus vulgaris L. harvested at four ontogenetic stages were evaluated for their biological activity and chemical composition. The thyme essential oils were tested for their inhibitory effects against nine strains of gram-negative bacteria and six strains of gram-positive bacteria. The bioimpedance method was chosen for studying the antibacterial activity of the essential oils and the parameter chosen for defining and quantifying the antibacterial activity of the essential oils was the detection time. The plate counting technique was used to study the inhibitory effect by direct contact. All the thyme essential oils examined had a significant bacteriostatic activity against the microorganisms tested. This activity was more marked against the gram-positive bacteria. The oil from thyme in full flower was the most effective at stopping the growth of the microbial species examined. The oils tested were also shown to have good antibacterial activity by direct contact, which appeared to be more marked against the gram-negative bacteria. Only a few of the species were capable of recovering at least 50% of their metabolic function after contact with the inhibitor, while most of the strains were shown to have been inactivated almost completely. Escherichia coli O157:H7 was the most sensitive species, given that after contact with even the lowest concentration of oil cells could not be recovered.

Anti-Bacterial Agents↗
PubMed1999

Relevance of hypointense lesions on fast fluid-attenuated inversion recovery MR images as a marker of disease severity in cases of multiple sclerosis.

BACKGROUND AND PURPOSE: Hypointense lesions can be visible on fast fluid-attenuated inversion recovery (FLAIR) MR images of the brain of patients with multiple sclerosis (MS), and they may be produced by severely damaged white matter. To test the role of these lesions as an MR marker of MS severity, we assessed their relationship with clinical findings and other MR measures. METHODS: Using a 1.5-T scanner, dual-echo rapid acquisition with relaxation enhancement, fast FLAIR, and T1-weighted MR images (24 axial, 5-mm-thick contiguous interleaved sections) were obtained from 50 patients (32 with relapsing-remitting and 18 with secondary progressive MS). RESULTS: Hypointense lesions were visible on the fast FLAIR images of 19 patients (mean number of lesions, 7.8; range 1-22); their median load was 1.4 mL (range, 0.05-12.6 mL). The median lesion load was significantly higher in patients with secondary progressive MS than in those with relapsing-remitting MS on the T1-weighted images. Both the number and the load of hypointense lesions shown by fast FLAIR imaging were significantly higher in patients with secondary progressive MS. Significant correlations were found between Expanded Disability Status Scale scores and MR lesion load. A multivariate analysis showed that only the presence of hypointense lesions on fast FLAIR images significantly separated cases of relapsing-remitting MS from cases of secondary progressive MS (relative risk, 7.1; 95% confidence interval, 2.0-25.9). CONCLUSION: The presence of hypointense lesions on fast FLAIR images was a strong predictor of disease severity in cases of MS, although the low sensitivity of this approach might limit its use for the assessment of MS evolution.

Adult↗
PubMed1999

Long-term changes of magnetization transfer-derived measures from patients with relapsing-remitting and secondary progressive multiple sclerosis.

BACKGROUND AND PURPOSE: For cases of multiple sclerosis (MS), magnetization transfer (MT) imaging may provide more pathologically specific and accurate estimates of the disease process than does conventional imaging. In this study, we evaluated changes of the MT ratio (MTR) of newly enhancing lesions, the MTR of normal-appearing white matter (NAWM), the average lesion MTR, and the MT histogram-derived metrics during a 3-year follow-up period for patients with relapsing-remitting or secondary progressive MS. METHODS: Dual-echo, conventional spin-echo, and MT images were obtained from seven patients with relapsing-remitting MS, seven patients with secondary progressive MS, and five age- and sex-matched control subjects at the time of study entry and 1, 13, and 37 months later. RESULTS: Newly enhancing lesions in the patients with secondary progressive MS presented a more severe and significant MTR reduction during the follow-up period as compared with those in the relapsing-remitting group. In cases of secondary progressive MS, we also observed a significant reduction of the MTR values of the NAWM and a trend toward reduction of average lesion MTR values. The patients with MS had mean percentage changes of MT histogram-derived measures that were approximately two to 10 times higher than those of the control subjects. CONCLUSION: This preliminary 3-year follow-up study shows that newly enhancing lesions and NAWM in patients with secondary progressive MS have significantly lower MTR values than do those in patients with relapsing-remitting MS. It also shows that the tissue damage that remains after enhancement ceases is more severe in secondary progressive disease.

Adult↗
PubMed1999

Comparison of three MR sequences for the detection of cervical cord lesions in patients with multiple sclerosis.

BACKGROUND AND PURPOSE: Improving the sensitivity of MR imaging for the detection of multiple sclerosis (MS) lesions in the cord might be useful in the diagnostic workup and could lead to a better understanding of the evolution of the disease. The purpose of this study was to compare fast spin-echo (FSE) with magnetization transfer-prepared gradient-echo (MT-GE) and fast short-inversion-time inversion recovery (fast-STIR) MR sequences to determine which is best for imaging cervical cord lesions in MS patients. METHODS: FSE, MT-GE, and fast-STIR MR images were obtained in 56 MS patients and 10 healthy control subjects with a 1.5-T MR system and a phased-array coil. Cord lesions seen on images obtained with each sequence were counted by two observers in two stages (stage 1: random review of the complete sets of images from each technique; stage 2: side-by-side review with a retrospective count of lesions). RESULTS: At the end of stage 1, a mean of 1.16 cord lesions per patient were seen on FSE images, 1.57 on MT-GE images (35% more than on FSE), and 1.92 on fast-STIR images (66% more than on FSE). Two or more cervical cord lesions were found on 16 FSE images (29%), 23 on MT-GE images (46%), and 30 on fast-STIR images (54%). Differences were reduced after stage 2: MT-GE detected 22% more lesions and fast-STIR 36% more lesions than FSE. Considering the three sequences together, 113 cervical cord lesions were seen in 50 patients (89%). CONCLUSION: Both MT-GE and fast-STIR sequences depict more cervical cord MS lesions than the FSE sequence, with fast-STIR having the best sensitivity. Fast-STIR MR images may be useful for the diagnostic workup of patients with suspected MS and for improving our understanding of the evolution of MS.

Adult↗