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Biomedical subjects

G Comi

Publications and source records attributed to G Comi.

At least 163 records · Page 9Linked to original sources
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↗
PubMed1999

Interscanner variation in brain MR lesion load measurements in multiple sclerosis using conventional spin-echo, rapid relaxation-enhanced, and fast-FLAIR sequences.

BACKGROUND AND PURPOSE: Different MR pulse sequences have been proposed for measuring multiple sclerosis (MS)-related abnormalities. The reproducibility of measured brain MS lesion volumes was compared for MR images performed using different scanners and different pulse sequences. METHODS: Nine patients with relapsing-remitting MS were each imaged on two scanners and, on each occasion, dual-echo conventional spin-echo, dual-echo rapid-acquisition relaxation-enhanced (RARE), and fast fluid-attenuated inversion recovery (fast-FLAIR) images were obtained. The lesion volume present on each image was evaluated three times by a single observer in random order, using a local thresholding technique. RESULTS: The mean lesion volumes present on fast-FLAIR images were significantly higher than those measured on dual-echo conventional spin-echo and RARE images. The mean intraobserver coefficients of variation for the different sequences and scanners ranged from 3.0% to 4.2% (no statistically significant difference). For each of the sequences, the use of different scanners introduced a variability that was higher than the intraobserver variability: the interscanner coefficient of variation was 7.4% for conventional spin-echo, 9.5% for RARE, and 18.5% for fast-FLAIR images. CONCLUSION: Our study confirms that the use of different scanners significantly influences lesion loads measured from MR images of patients with MS and establishes that newer sequences are more susceptible to measurement variability. It also indicates that, if newer sequences are to be used in clinical trials, careful standardization is needed.

Adult↗
PubMed1998

Central nervous system delivery of interleukin 4 by a nonreplicative herpes simplex type 1 viral vector ameliorates autoimmune demyelination.

Multiple sclerosis (MS) is a T cell-mediated organ-specific inflammatory disease leading to central nervous system (CNS) demyelination. On the basis of results obtained in experimental autoimmune encephalomyelitis (EAE) models, MS treatment by administration of antiinflammatory cytokines such as interleukin 4 (IL-4) is promising but is hampered by the limited access of the cytokines to the CNS and by the pleiotropic effects of systemically administered cytokines. We established a cytokine delivery system within the CNS using non-replicative herpes simplex type 1 (HSV-1) viral vectors engineered with cytokine genes. These vectors injected into the cisterna magna (i.c.) of mice diffuse in all ventricular and subarachnoid spaces and infect with high efficiency the ependymal and leptomeningeal cell layers surrounding these areas, without obvious toxic effects. Heterologous genes contained in the vectors are efficiently transcribed in infected ependymal cells, leading to the production of high amounts of the coded proteins. For example, 4.5 ng of interferon gamma (IFN-gamma) per milliliter is secreted into the cerebrospinal fluid (CSF) up to day 28 postinjection (p.i.) and reaches the CNS parenchyma in bioactive form, as demonstrated by upregulation of MHC class I expression on CNS-resident cells. We then exploited the therapeutic potential of the vectors in EAE mice. An HSV-1-derived vector containing the IL-4 gene was injected i.c. in Biozzi AB/H mice at the time of EAE induction. We found the following in treated mice: (1) delayed EAE onset, (2) a significant decrease in clinical score, (3) a significant decrease in perivascular inflammatory infiltrates and in the number of macrophages infiltrating the CNS parenchyma and the submeningeal spaces, and (4) a reduction in demyelinated areas and axonal loss. Peripheral T cells from IL-4-treated mice were not affected either in their antigen-specific proliferative response or in cytokine secretion pattern. Our results indicate that CNS cytokine delivery with HSV-1 vectors is feasible and might represent an approach for the treatment of demyelinating diseases. Advantages of this approach over systemic cytokine administration are the high cytokine level reached in the CNS, the absence of effects on the peripheral immune system, and the long-lasting cytokine production in the CNS after a single vector administration.

Animals↗
PubMed1998

Magnetization transfer ratios of multiple sclerosis lesions with variable durations of enhancement.

We evaluated whether new multiple sclerosis (MS) lesions with variable durations of enhancement have different magnetization transfer ratios (MTR) at the time of their appearance. We scanned ten patients with relapsing-remitting MS every four weeks on four occasions. During each of the monthly sessions, we obtained dual echo, MT and T1-weighted scans. Five minutes after gadolinium-DTPA (Gd) injection, another T1-weighted scan was obtained. We measured the MTR of new enhancing lesions on co-registered quantitative MTR images. During the three-month follow up, 54 new enhancing lesions were seen with a mean MTR value of 33.6% (SD=7.8%). The mean MTR values were 35.3% (SD=7.0%) for lesions enhancing on only one scan and 29.3% (SD=8.6%) for those enhancing on at least two consecutive scans (P=0.01). These results suggest that enhancing lesions in MS have heterogeneous pathological substrates, which may be associated with different durations of the enhancing phase.

Adult↗
PubMed1998

A rapid method for the identification and partial serotyping of Listeria monocytogenes in food by PCR and restriction enzyme analysis.

Two highly specific primers for Listeria monocytogenes were used to yield from foods such as milk, soft cheese and meat, PCR products that were cleaved with the restriction enzyme HindIII. The fragments generated allowed a distinction between two groups of L. monocytogenes serovars: serovars 1/2a and 1/2c cluster in one group and serovars 1/2b, 3b and 4b in the other subgroup. Since this procedure can be completed in 24 h, an epidemiological association between human disease and suspected sources can be rapidly confirmed at the subgroup level in the laboratory.

Animals↗
PubMed1998

A longitudinal brain MRI study comparing the sensitivities of the conventional and a newer approach for detecting active lesions in multiple sclerosis.

Monthly dual-echo spin-echo (SE) and enhanced magnetic resonance imaging (MRI) after the injection of a standard dose (SD) of gadolinium (Gd) is the conventional approach to monitor short-term disease activity in multiple sclerosis (MS). In this study, the sensitivity of this approach in detecting active lesions in MS was compared with that of monthly fast fluid attenuated inversion recovery (FLAIR) scans associated with enhanced MRI after the injection of a triple dose (TD) of Gd. Thirteen patients with relapsing-remitting MS entered the study. Monthly MRI scans were obtained on four occasions in two separate sessions (interval between 12 and 24 h). In one session, dual-echo conventional SE and SD Tl-weighted scans were obtained; in the other, fast-FLAIR and TD Tl-weighted scans. The order of the two sessions was randomized. Three observers counted the number of active lesions detected by each of the two approaches. One hundred and four active lesions were detected by the conventional approach and 199 by the newer approach (average increase per patient = 75%, range = 0-325%). The mean number of active lesions per month per patient was 2.0 for the conventional approach and 3.8 for the new approach (P = 0.004). Scans with active lesions were 34/52 (65%) with the conventional approach and 37/52 (71%) with the new approach. Our data indicate that the combined use of monthly fast-FLAIR and TD enhanced Tl-weighted scans increases the number of active lesions detected on serial MRI scans from patients with MS.

Adult↗
PubMed1998

Quantitative volumetric analysis of brain magnetic resonance imaging from patients with multiple sclerosis.

We compared the volumes of the brain as a whole and of different cerebral structures from patients with multiple sclerosis (MS) and normal subjects. In the patients, we also correlated brain volumes with T2 and T1 lesion loads and disability. A magnetization-prepared rapid acquisition gradient echo (MP RAGE) sequence with subsequent reconstruction of axial 1-mm thick slices and a dual-echo sequence were obtained in 15 patients with relapsing-remitting or secondary progressive MS and 15 sex-, age-, height- and weight-matched normal subjects. The brains and the different cerebral structures studied (cerebral hemispheres, cerebellum and brainstem) were segmented manually by a single observer on the 1-mm MP RAGE scans. The hyperintense lesion volumes seen on dual-echo scans and the hypointense lesion volumes seen on the 1-mm MP RAGE scans were measured using a semi-automated segmentation technique based on local thresholding. Compared to the normal volunteers, patients had significantly lower cerebral (P = 0.008), hemispheric (P = 0.01) and brainstem (P = 0.03) volumes. Cerebral atrophy was detected in seven (47%) MS patients. Patients with brainstem signs had significantly lower mean brainstem volume than the others (P = 0.04). No significant correlations were found between the cerebral volumes and the EDSS scores, the hyperintense lesion volumes and the hypointense lesion volumes. We conclude that cerebral atrophy is a relatively frequent finding in MS, but its relationship with physical disability is modest.

Adult↗
PubMed1998

A one year study of new lesions in multiple sclerosis using monthly gadolinium enhanced MRI: correlations with changes of T2 and magnetization transfer lesion loads.

In this study, 14 patients with either relapsing-remitting or secondary progressive multiple sclerosis (MS) were scanned monthly using gadolinium enhanced magnetic resonance imaging (MRI). At the start of the study and at 1 year follow up, T2-weighted and magnetization transfer (MT) scans were also performed. The correlation between the frequency and extent of enhancement and changes of lesion load over a 1 year period on T2-weighted and MT images were assessed. For all patients, and for the relapsing-remitting patients only, the number and volume of enhancing lesions per month showed no significant correlation with the change between baseline and 1 year follow up of lesion volumes on T2 and MT images. However, strong correlations were found between the number and volume of gadolinium enhancing lesions with changes of T2 (r = 0.93, P = 0.02) and MT (r = 0.82, P = 0.04) lesion loads in patients with secondary progressive MS. Strong correlations were also found between the lesion loads on T2-weighted scans and on MT images both at baseline and at 1 year follow up (r = 0.83, P = 0.003). In addition, the changes in lesion load over 1 year, detected using the two techniques, were moderately correlated (r = 0.51, P = 0.05). This study provides further evidence that the pathological processes in MS are at different stages in relapsing-remitting and secondary progressive MS. It also suggests that the effectiveness of recovery mechanisms within lesions might be one of the major factors responsible for such a difference.

Adult↗