Biomedical subjects

R Longo

Publications and source records attributed to R Longo.

At least 37 records · Page 2Linked to original sources

PubMed2002

The inhibitory effect of propolis and caffeic acid phenethyl ester on cyclooxygenase activity in J774 macrophages.

The effect of an ethanolic extract of propolis, with and without CAPE, and some of its components on cyclooxygenase (COX-1 and COX-2) activity in J774 macrophages has been investigated. COX-1 and COX-2 activity, measaured as prostaglandin E2 (PGE2) production, were concentration-dependently inhibited by propolis (3 x 10(-3) - 3 x 10(2) microgml(-1)) with an IC50 of 2.7 microgml(-1) and 4.8 x 10(-2) microgml(-1), respectively. Among the compounds tested pinocembrin and caffeic, ferulic, cinnamic and chlorogenic acids did not affect the activity of COX isoforms. Conversely, CAPE (2.8 x 10(-4) - 28 microgml(-1); 10(-9) - 10(-4) M) and galangin (2.7 x 10(-4) - 27 microgml(-1); 10(-9) - 10(-4) M) were effective, the last being about ten-twenty times less potent. In fact the IC50 of CAPE for COX-1 and COX-2 were 4.4 x 10(-1) microgml(-1) (1.5 x 10(-6) M) and 2 x 10(-3) microgml(-1) (6.3 x 10(-9) M), respectively. The IC50 of galangin were 3.7 microgml(-1) (15 x 10(-6) M) and 3 x 10(-2) microgml(-1) (120 x 10(-9) M), for COX-1 and COX-2 respectively. To better investigate the role of CAPE, we tested the action of the ethanolic extract of propolis deprived of CAPE, which resulted about ten times less potent than the extract with CAPE in the inhibition of both COX-1 and COX-2, with an IC50 of 30 microgml(-1) and 5.3 x 10(-1) microgml(-1), respectively. Moreover the comparison of the inhibition curves showed a significant difference (p < 0.001). These results suggest that both CAPE and galangin contribute to the overall activity of propolis, CAPE being more effective.

Animals↗

PubMed2001

An innovative digital imaging set-up allowing a low-dose approach to phase contrast applications in the medical field.

Recently, new imaging modalities based on the detection of weak phase perturbations effects, among which are phase contrast and diffraction imaging, have been developed by several researchers. Due to their high sensitivity to weakly absorbing details, these techniques seem to be very promising for applications in the medical field. On the other hand, digital radiology is undergoing a wide diffusion, and its benefits are presently very well understood. Up to now, however, the strong pixel size constraints associated with phase contrast pattern detection limited the possibility of exploiting the advantages of phase contrast in digital radiology applications. In this paper, an innovative setup capable of removing the pixel size constraints, and thus opening the way to low dose digital phase contrast imaging, is described. Furthermore, we introduce an imaging technique based on the detection of radiation scattered at small angles: the information extracted from the sample is increased at no dose expense. We believe that several radiological fields, mammography being the first important example, may benefit from the herein described innovative imaging techniques.

Diagnostic Imaging↗

PubMed2000

Cortical-basal ganglionic degeneration: a clinical, functional and cognitive evaluation (1-year follow-up).

We decided to evaluate a patient who was diagnosed with cortical-basal ganglionic degeneration from a clinical, instrumental and neuropsychological perspective. Our aim was to employ a new instrumental tool, functional magnetic resonance, in order to evaluate his cortical damage. We then followed the pathological course for 1 year and tested the patient again: we discuss the results of our evaluation, having an overview of the literature on the topic. In particular, we focused our attention on his apraxia, trying to suggest a dynamic and anatomical model to guarantee a possible explanation of his behavior.

Aged↗

PubMed2000

Experimental evaluation of a simple algorithm to enhance the spatial resolution in scanned radiographic systems.

In order to ensure an early diagnosis of breast cancer, an imaging system must fulfil extremely stringent requirements in terms of dynamic range, contrast resolution and spatial resolution. Furthermore, in order to reduce the dose delivered to the patient, a high efficiency of the detector device should be provided. In this paper the SYRMEP/FRONTRAD (SYnchrotron Radiation for MEdical Physics/FRONTier RADiology) mammography project, based on synchroton radiation and a novel solid state pixel detector, is briefly described. Particular relevance is given to the fact that the radiographic image is obtained by means of a scanning technique, which allows the possibility of utilizing a scanning step smaller than the pixel size. With this procedure, a convolution between the real image and the detector point spread function (PSF) is actually acquired: by carefully measuring the detector PSF, it is possible to apply a post-processing procedure (filtered deconvolution), which reconstructs images with enhanced spatial resolution. The image acquisition modality and the deconvolution algorithm are herein described, and some test object images, with spatial resolution enhanced by means of the filtered deconvolution procedure, are presented. As discussed in detail in this paper, this procedure allows us to obtain a spatial resolution determined by the scanning step, rather than by the pixel size.

Algorithms↗

PubMed2000

Mammography with synchrotron radiation: phase-detection techniques.

The authors evaluated the effect on mammographic examinations of the use of synchrotron radiation to detect phase-perturbation effects, which are higher than absorption effects for soft tissue in the energy range of 15-25 keV. Detection of phase-perturbation effects was possible because of the high degree of coherence of synchrotron radiation sources. Synchrotron radiation images were obtained of a mammographic phantom and in vitro breast tissue specimens and compared with conventional mammographic studies. On the basis of grades assigned by three reviewers, image quality of the former was considerably higher, and the delivered dose was fully compatible.

Absorption↗

PubMed1999

The role of nitric oxide in aloe-induced diarrhoea in the rat.

The role of nitric oxide (NO) on aloe-induced diarrhoea was studied in the rat. Nine hours after oral administration, aloe produced diarrhoea at doses of 5 g kg(-1)(20% rats with diarrhoea) and 20 g kg(-1) (100% of rats with diarrhoea). Lower doses of aloe (0.1 and 1 g kg(-1) did not produce a diarrhoeal response. Pre-treatment (i.p.) of rats with the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME 2.5-25 mg kg(-1) reduced the diarrhoea induced by aloe (20 g kg(-1) 9 h after its oral administration. L-NAME (25 mg kg(-1)) also reduced the increase in faecal water excretion produced by aloe (20 g kg(-1). L-arginine (1500 mg kg(-1), i.p.), administered to rats pre-treated with L-NAME (25 mg kg(-1), drastically reduced the effect of L-NAME on diarrhoea and increase in faecal water excretion induced by aloe (20 g kg(-1). Given alone, L-arginine did not modify aloe-induced diarrhoea. Basal Ca2+ -dependent NO synthase activity in the rat colon was dose-dependently inhibited by aloe (0.1-20 g kg(-1)) and by aloin (0.1-1 g kg(-1)), the active ingredient of aloe. These results suggest that endogenous NO modulates the diarrhoeal effect of aloe.

Aloe↗

PubMed1998

Proton magnetic resonance spectroscopy during transient global amnesia.

There is uncertainty about the etiology of transient global amnesia and none of the pathogenetic hypotheses proposed so far, i.e. transient ischemia, epileptic discharge and spreading depression of cortical electrical activity, is completely satisfactory. Using water suppressed proton magnetic resonance spectroscopy we studied one patient during a typical episode of transient global amnesia and 2 weeks thereafter in order to investigate the metabolic changes in the hippocampal region. In both hippocampi, spectra of N-acetyl-aspartate, creatine-phosphocreatine, compounds containing choline and lactate failed to show changes consistent with cerebral ischemia, both in the acute phase and in the follow-up. Spreading depression in response to emotional stress seems a likely explanation in this patient, who suffered from migraine in the past.

Aged↗

PubMed1998

Quantitative analysis of basic fibroblast growth factor and vascular endothelial growth factor in human colorectal cancer.

Tumour growth is angiogenesis dependent. Some authors suggest a prognostic role of microvessel count in colorectal cancer. We tested the role of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) in the switch to the angiogenic phenotype in 35 patients with colorectal cancer at different stages of disease. We evaluated the two angiogenic factors, by enzyme-linked immunosorbent assay (ELISA), in tumour, peritumoral mucosa, pathological mesenteric and peripheral blood. We used ten endoscopic intestinal biopsies and ten peripheral blood samples from healthy subjects as control. bFGF was significantly lower in tumour tissues and in peritumoral mucosas than in healthy mucosas, whereas VEGF was up-regulated in tumours but not in peritumoral mucosa. Both angiogenic factors were greatly increased in mesenteric blood. VEGF tumour and serum levels were significantly correlated with the stage of disease. bFGF tumour and serum concentration were not correlated with the stage of disease. The high levels of bFGF in mesenteric blood suggest that this growth factor might be abnormally released from tumour tissue and peritumoral mucosa and could function as an early effector in the switch to the angiogenic phenotype. In contrast, VEGF, whose levels show a significant correlation with the stage of disease, could act in a following step, supporting tumour progression.

Adult↗

PubMed1998

Low-dose phase contrast x-ray medical imaging.

Phase contrast x-ray imaging is a powerful technique for the detection of low-contrast details in weakly absorbing objects. This method is of possible relevance in the field of diagnostic radiology. In fact, imaging low-contrast details within soft tissue does not give satisfactory results in conventional x-ray absorption radiology, mammography being a typical example. Nevertheless, up to now all applications of the phase contrast technique, carried out on thin samples, have required radiation doses substantially higher than those delivered in conventional radiological examinations. To demonstrate the applicability of the method to mammography we produced phase contrast images of objects a few centimetres thick while delivering radiation doses lower than or comparable to doses needed in standard mammographic examinations (typically approximately 1 mGy mean glandular dose (MGD)). We show images of a custom mammographic phantom and of two specimens of human breast tissue obtained at the SYRMEP bending magnet beamline at Elettra, the Trieste synchrotron radiation facility. The introduction of an intensifier screen enabled us to obtain phase contrast images of these thick samples with radiation doses comparable to those used in mammography. Low absorbing details such as 50 microm thick nylon wires or thin calcium deposits (approximately 50 microm) within breast tissue, invisible with conventional techniques, are detected by means of the proposed method. We also find that the use of a bending magnet radiation source relaxes the previously reported requirements on source size for phase contrast imaging. Finally, the consistency of the results has been checked by theoretical simulations carried out for the purposes of this experiment.

Biopsy↗

PubMed1998

Mammography of a phantom and breast tissue with synchrotron radiation and a linear-array silicon detector.

A linear-array, silicon pixel detector, capable of counting single photons, was applied to mammography by using a synchrotron radiation beam. Images were obtained of both a mammographic phantom and a breast-tissue sample. The phantom image was acquired with a mean glandular dose of 0.32 mGy. This detector combined with a synchrotron radiation beam allows acquisition of high-contrast, low-dose images of soft tissues.

Breast↗

PubMed1997

Bone marrow relaxation times in Gaucher disease before and after enzyme replacement therapy.

The aim of this work was to monitor the effectiveness of enzyme replacement therapy on the basis of the changes in T1 relaxation times in Gaucher patients. A total of 26 patients underwent MR before enzyme replacement therapy; of them, 18 have been followed-up. A total of 22 age-matched controls underwent the same MR study. Scans were focused on the femoral neck, and T1 relaxation times were measured by means of a mixed spin-echo inversion recovery sequence. The T1 relaxation times in Gaucher patients were significantly longer than normal (p < 0.05). After enzyme replacement therapy, T1 relaxation times gradually became closer to those of control subjects, and there was also a significant decrease (p < 0.01) with respect to values before therapy, probably due to an increase in the fat/water ratio. Evaluation of T1 relaxation time may supply a useful indication of Gaucher disease regression after enzyme replacement therapy particularly in those cases in which a normal skeletal appearance corresponds to prolonged T1 relaxation times.

Adolescent↗

PubMed1997

Noninvasive in vivo quantitative assessment of fat content in human liver.

BACKGROUND/AIMS: Since the introduction of ultrasonography, liver steatosis has become an increasingly frequent diagnosis. Both ultrasonography (US) and computerized tomography (CT) provide qualitative rather than quantitative assessment of fatty infiltration. The objective of this study was to develop a noninvasive method for the quantification of the hepatic fat content in vivo. A test object containing solutions with CT scan density (CTD) similar to normal liver ("liver-equivalent") or "fat-equivalent material" in variable proportions was prepared to measure patients with variable degrees of steatosis in vivo. RESULTS: A linear correlation (r=0.99, p<0.001) linked CTD and the increasing percentage of fat-equivalent material. A CTD calibration curve was derived as a reference for the in vivo determinations. In 29 consecutive patients with steatosis diagnosed by histology, CTD was linearly correlated (r=0.83, p<0.001) with the hepatic fat content (HFC) expressed as percent of the whole liver, obtained by a computerized histomorphometric analysis. Based on the calibration curve obtained in 29 subjects who underwent liver biopsy, 38 additional consecutive steatotic patients were examined and the degree of hepatic fat content was calculated. The HFC was linearly correlated (r=-0.86, p<0.001) with the liver-to-spleen ratio. CONCLUSIONS: We conclude that the use of test objects allows an accurate and reproducible noninvasive quantitative assessment of hepatic fat infiltration in humans. This technique may prove useful in the evaluation of the natural course and treatment of hepatic steatosis as well as in the assessment of donor livers prior to transplantation.

Adult↗

PubMed1997

Assessment of pituitary microadenomas: comparison between 2D and 3D MR sequences.

The aim of this study was to compare the diagnostic value and image quality of two different T1-weighted MR sequences in the evaluation of PRL-secreting pituitary microadenomas. Twenty-four patients with a clinical diagnosis of pituitary microprolactinoma were prospectively examined with both a 2D SE and a 3D turbo-SE T1-weighted coronal sequence, before and after intravenous contrast medium administration. Evaluation of MR images was done only on postcontrast images and considered the number of slices in which the lesions were visible and image quality, which was evaluated by both a subjective score and objective parameters (signal-to-noise and contrast-to-noise ratios). Pituitary microprolactinomas are visible in a higher number of slices in 3D TSE sequences; the subjective scores for image quality and signal-to-noise ratios were similar in both 2D and 3D sequences; the contrast-to-noise ratio was always higher in 3D sequences. In patients with hyperprolactinemia, the authors recommend using coronal 3D TSE T1-weighted sequences for evaluation of the pituitary region. 2D SE T1-weighted sequences may be considered if a shorter examination time is required (i.e., for claustrophobic patients) and in assessment or follow-up of microadenomas when a larger size lesion is clinically suspected.

Adult↗

PubMed1997

A linear array silicon pixel detector: images of a mammographic test object and evaluation of delivered doses.

We present images of a mammographic test object obtained using a linear array silicon pixel detector capable of single-photon counting. The detector pixel size was 200 x 300 microns2 and images were acquired by scanning the test object between the laminar detector and the x-ray source with a scanning step of 100 microns. A molybdenum anode tube was used with two different filtrations: 2 mm aluminium and 25 microns molybdenum. Conventional film-screen images were also obtained in order to compare spatial and contrast resolution. In our digital images it is possible to recognize low-contrast details having dimensions smaller than or equal to the dimensions of details visible by means of a clinical mammographic unit. The detection of microcalcifications smaller than 150 microns was possible only when using the Mo filtration. However a copper wire of 50 microns diameter was detectable when embedded in a simulated tissue. We discuss in detail the mean glandular doses (MGDs) delivered during the image acquisition. The MGDs necessary to obtain good-quality images are always smaller than at a conventional mammographic unit. Since MGDs depend on the x-ray spectrum, the dose reduction becomes larger when the applied spectrum is harder than in film-screen acquisition (Al filtration and 35 kVp).

Female↗

PubMed1997

[Comparison of magnetic resonance Spin-echo sequences and fat-suppressed sequences in bone diseases].

Thirty-two patients affected with skeletal conditions were examined with MRI using Short TI Inversion Recovery sequence and Spectral Presaturation with Inversion Recovery (SPIR) sequence as well as Spin-Echo (SE) T1-weighted sequence and Fast Spin-Echo (FSE) T2-weighted sequence to compare their value in the assessment of skeletal lesions. SPIR sequence was performed after intravenous injection of Gd-DTPA. The lesions included primary bone tumors (10 cases: 1 osteosarcoma, 1 periosteal sarcoma, 1 Ewing's sarcoma, 1 chondrosarcoma, 2 non-ossifying fibromas, 1 chondroma, 1 chondromyxoid fibroma, 1 desmoplastic fibroma and 1 bone cyst), metastases (7 cases: 3 prostate, 3 breast, 1 lung-squamous cell carcinoma), infections (12 cases: 9 osteomyelitis, 3 spondylodiscitis), sacroiliitis (1 case) and posttraumatic bone bruise (2 cases of bone marrow edema). The four sequences were compared by using both qualitative and quantitative evaluation. Qualitative evaluation showed that STIR sequence was better than SPIR sequence (performed with Gd-DTPA) for lesion conspicuity (p < .016) and for signal intensity uniformity (p < .03). Compared with SE T1 and FSE T2 sequences, fat-suppressed sequences were superior for conspicuity, margins, and extension of the lesions (range of p < .001-.017). Only SPIR with Gd-DTPA sequence, compared with SE T1 sequence for lesion conspicuity was not statistically significantly different. Quantitative evaluation showed statistically significant higher values of percent contrast (%C) and contrast-to-noise ratio (C/N) for STIR sequence compared with SPIR sequence (%C p < .004; C/N p < .040). This study suggests that STIR sequence and SE T1-weighted sequence provide high sensitivity in lesion detection and good anatomical definition. The use of a fat-suppressed sequence with Gd-DTPA can be useful for lesion characterization.

Adolescent↗

PubMed1996

Selective opposite modulation of dentate granule cells excitability by mu and kappa opioids in rat hippocampal slices.

The effects of opioids having affinity for kappa (U50,488H and U54,494A) and mu receptors (DAMGO and methadone) were tested on the excitability of the dentate and CA1 neurons in rat hippocampal slices. Slice perfusion with 25 microM U50,488H or with 12 microM U54,494A produced within 60 min a significant (P < 0.05) decrease in the amplitude of the primary dentate population spike (PS). A similar decrease occurred on the CA1 PS amplitude only at concentrations higher than 100 microM of U50,488H or 50 microM of U54,494A. Slice perfusion with 0.5 microM DAMGO, or 100 microM methadone produced an increase in the amplitude of the primary dentate and CA1 PS and the appearance of secondary PSs. Slice perfusion with 12 microM U50,488H or with 25 microM of methadone significantly (P < 0.05) decreased or increased, respectively, the rate of appearance of the dentate posttetanic potentiation (PTP) and long-term potentiation (LTP) after a 100 Hz tetanic stimulation of the perforant path. The same concentration of U50,488H or methadone did not affect the rate of appearance of the CA1 PTP and LTP after a 100 Hz tetanic stimulation of the Schaffer collaterals. The data, providing evidence for a selective opposite modulation by mu and kappa opioids on the basal and stimulated dentate neuronal excitability, indicate the dentate area as a target within the hippocampus for an opposite influence between mu and kappa opioids on neuronal excitability.

Animals↗

PubMed1996

7-chlorokynurenic acid prevents in vitro epileptiform and neurotoxic effects due to kainic acid.

1. The effects of 7-chlorokynurenic acid were studied against the epileptiform and neurotoxic effects due to the non-NMDA excitatory amino acid, kainic acid, in rat hippocampal slices. 2. Slice perfusion with 7-chlorokynurenic acid (100 microM), significantly (p < 0.05) decreased the duration of the CA1 epileptiform bursting due to 1 microM kainic acid. 3. Slice perfusion with 7-chlorokynurenic acid (100 microM) significantly (p < 0.05) increased the probability of recovery of the CA1 population spike after a neurotoxic concentration (12 microM) of kainic acid. 4. The results indicate that 7-chlorokynurenic acid affects, with a similar potency, epileptiform and neurotoxic effects due to kainic acid.

Animals↗

PubMed1996

In vivo biological response following low-dose interleukin-2 in complete remission B-cell non-Hodgkin's lymphoma patients. Italian Lymphoma Study Group (GISL).

The aim of the present study is to verify whether recombinant interleukin-2 (rIL-2) at low doses is well tolerated in aggressive lymphoma in complete remission (CR), and if there may be a biological justification for its use as a remission-maintenance therapy able to reduce the percentage of relapses. We treated 6 patients with B-cell non-Hodgkin's lymphoma (B-NHL) in CR following PM-Cytabom with rIL-2 3 IMU s.c. x 5 d per wk, every other wk for 8 wk. Our results show that this treatment provokes statistically significant changes in the absolute number of lymphocytes, eosinophils, CD25+ and CD122+ cells and soluble IL-2 receptors; these doses, however, are not sufficient to modify CD3+, CD16+ and CD56+ cell values or natural killer and lymphokine activated killer cell activity. Thus these findings do not appear to constitute a biological rationale for the use of rIL-2 at this dose and schedule as a remission-maintenance therapy in B-cell NHL. Nevertheless, the results are a valid basis for further study of the use of the same rIL-2 doses for a longer period of time in combination with other cytokines, in the hope that the biological effects can be augmented without increasing the toxic side effects.

Cytokines↗