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S Rossi

Publications and source records attributed to S Rossi.

At least 109 records · Page 6Linked to original sources
PubMed2001

Pilot dose-finding trial on interferon alpha in combination with ribavirin for the treatment of chronic hepatitis C in patients not responding to interferon alone.

BACKGROUND: Effectiveness of combination therapy with standard interferon alpha doses and ribavirin is far from being demonstrated in patients with hepatitis C non responders to interferon alpha monotherapy. Recent kinetic studies revealed that these doses may be suboptimal. AIMS: To find the criteria for optimisation of the interferon dose, to be used in combination with ribavirin in patients with hepatitis C non responders to interferon alpha monotherapy. PATIENTS: Sixty-three patients enrolled in a pilot controlled trial were treated for 6 months with ribavirin ([1000-1200 mg daily) and were randomised to concurrently receive interferon alpha 2b for 6 months at: 3 Million Units thrice weekly [group A (21 patients)], 5 MU thrice weekly [group B (21 patients)] and 5 million units daily [group C (21 patients)]. RESULTS: A sustained virological response was observed in: 1 patient from group A (5%), 2 patients from group B (9%) and 8 patients from group C (38%; p=0.02 vs group A; p=0.03 vs group B). Side-effects were not significantly different between the 3 groups. Multivariate analysis showed that infection by hepatitis C virus genotypes 2 or 3 and interferon alpha dosage of 5 million units daily were independent predictors of sustained response. CONCLUSIONS: These results suggest that higher interferon doses administered daily in combination with ribavirin could be more effective in those patients with hepatitis C who had not responded to interferon alone.

Adolescent↗
PubMed2001

Prefrontal [correction of Prefontal] cortex in long-term memory: an "interference" approach using magnetic stimulation.

Neuroimaging has consistently shown engagement of the prefrontal cortex during episodic memory tasks, but the functional relevance of this metabolic/hemodynamic activation in memory processing is still to be determined. We used repetitive transcranial magnetic stimulation (rTMS) to transiently interfere with either left or right prefrontal brain activity during the encoding or retrieval of pictures showing complex scenes. We found that the right dorsolateral prefrontal cortex (DLPFC) was crucial for the retrieval of the encoded pictorial information, whereas the left DLPFC was involved in encoding operations. This 'interference' approach allowed us to establish whether a cortical area activated by a memory task actually contributes to behavioral performance.

Adult↗
PubMed2001

Electrogram width parameter analysis in implantable cardioverter defibrillators: Influence of body position and electrode configuration.

The "EGM width criterion" is a discrimination algorithm that was available in the last generation ICDs. It improved ventricular tachycardia detection by withholding inappropriate therapy deliveries in the presence of narrow QRS tachycardias. The accuracy of the algorithm depends on the optimal settings of the intracardiac EGM source, the "slew thresholds," and the "width threshold." The possible dependence of these parameters on body position may affect the detection efficacy. Whether these effects can be minimized by a proper choice of the electrode configuration used for signal analysis is still to be investigated. This study aimed to evaluate the stability of the slew threshold and width threshold obtained in the supine and orthostatic positions detected by the tip-to-ventricular coil and can-to-ventricular coil electrode configurations. Their time dependence was also evaluated at the 6-month follow-up. Fifty-eight patients who were recipients of an ICD (model Medtronic 7223cx and 7227cx) were included in the study. Changing from supine to orthostatic position caused a marked variation of slew and width thresholds (21.0 +/- 13.9 V/s and 10.1 +/- 9.6 ms, respectively) in 36% of patients with tip-to-ventricular coil and in 44% of patients with can-to-defibrillating coil (the mean slew threshold variation was in this case 17.6 +/- 15.8 V/s, while the mean width threshold variation was 18.8 +/- 21.0 ms). Width threshold variation was statistically significant (P < 0.02) with the latter electrode configuration. Slew thresholds settings changed between the 1- and 6-month follow-ups in the 75% of patients with can-to-defibrillating coil configuration and in 50% with tip-to-defibrillating coil. These time related variations were significantly larger with the tip-to-defibrillating coil configuration (P < 0.01). In conclusion, EGM width parameters may change between supine and orthostatic position and over time with tip-to-defibrillating coil configuration and can-to-defibrillating coil configuration. The former configuration was less sensitive to body position changes, but more sensitive to time related variations. These findings may be useful for optimal programming of the EGM width criterion, but if parameter programming based on these results can improve the discrimination specificity still needs to be investigated.

Aged↗
PubMed2001

Hypothesis testing in a rule discovery problem: when a focused procedure is effective.

We investigated individuals' ability to use negative evidence in hypothesis testing. We compared performance in two versions of Wason's (1960) rule discovery problem. In the original version, a triple of numbers--(2, 4, 6)--was presented as an example of a rule that the experimenter had in mind (i.e., "increasing numbers"). Participants had to discover the rule by proposing new triples. In the other version, the same triple was presented as a counter-example to the experimenter's rule (i.e., "decreasing numbers"). We predicted that, in both conditions, participants would form hypotheses based on the features of the triple, and test only instances of the hypothesized rule. However, in the counter-example condition, such focused testing would invariably produce negative evidence. As a consequence, participants would be forced to revise their hypotheses. The reported results corroborated our predictions: Participants solved the counter-example version significantly better than the original problem.

Adult↗
PubMed2001

Development of a mucoadhesive dosage form for vaginal administration.

The antimycotic imidazole derivative clotrimazole is employed locally for the treatment of genitourinary tract mycotic infections and is formulated as creams, foams, tablets, gels, irrigations, or pessaries. In this study, a new dosage form was developed by including bioadhesive polymers (polycarbophyl, hydroxypropylmethylcellulose, and hyaluronic sodium salt) into pessaries made of semisynthetic solid triglycerides. These polymers hold the delivery systems in the vaginal tract for a few days without any toxic effects or important physiological modifications, prolonging the permanence of the drug on the vaginal mucosa. Technological controls (compatibility with differential scanning calorimetry [DSC] studies, particle size analysis, and liquefaction time test) and biopharmaceutics studies for the evaluation of the release of the drug from the dosage form and of the bioadhesive properties were carried out. Moreover, a new test for the evaluation of the permanence of the drug in a simulated application site was developed from a modification of the Satnikar and Fantelli method for the evaluation of the liquefaction time of rectal suppositories. This test simulates the physiological vaginal condition and verifies the efficiency of the polymers in prolonging the permanence of the dosage form in the location where it is applied. The technological controls demonstrated that the presence of the polymers did not have an influence on the characteristics of the pessaries. On the other hand, there was an improvement in adhesivity of the pessaries in the in vitro adhesion test and prolonging of the liquefaction time in the liquefaction time test in the presence of mucoadhesive polymers, which increased with increasing polymer concentration. The presence of the mucoadhesive had a large influence on the permanence of the drug in the simulated application site because it modified the distribution of the drug along the simulated application site. In conclusion, the developed new formulations showed good technological and adhesion properties and the capacity of hold the dosage form in the target site. Among the employed bioadhesive polymers, the best behavior in the performed test was by polycarbophyl at its maximum concentration.

Administration, Intravaginal↗
PubMed2001

Brain oxygen tension, oxygen supply, and oxygen consumption during arterial hyperoxia in a model of progressive cerebral ischemia.

We investigated the changes in brain oxygen tension (ptiO2) after ventilation with pure O2 in order to (1) clarify the pathophysiology of O2 exchange in the cerebral microcirculation; and (2) investigate the relationship between brain O2 tension, O2 delivery, and consumption in steady-state conditions during stepwise cerebral blood flow (CBF) reductions. A swine model was developed to reduce CBF in three stable steps: (1) baseline (CBF 100%), (2) CBF of 50-60% of baseline, and (3) CBF of <30% of baseline. CBF was reduced by infusing saline into the left lateral ventricle through a catheter connected with an infusion pump. At each step, hyperoxia was tested by increasing the inspired oxygen fraction up to 100%, PtiO2 reflected the CBF reductions, since it was respectively 27.95 (+/-10.15), 14.77 (+/-3.58), and 3.45 (+/-2.89) mm Hg during the three CBF steps. Hyperoxia was followed by an increase in ptiO2, although the increase was significantly lower when hyperoxia was applied during progressive ischemia. O2 supply to the brain did not change during hyperoxia. Arteriovenous oxygen difference (AVDO2) decreased during the phases of intact CBF and moderate impairment, but not during the phase of severe CBF reduction. In conclusion, ptiO2 reductions closely reflect the imbalance between oxygen delivery and demand; this implies a link between low ptiO2 and defective O2 supply due to impaired CBF. However, this relation is not necessarily reciprocal, since manipulating brain oxygen tension does not always influence brain oxygen delivery, as in the case of ventilation with pure oxygen.

Animals↗
PubMed2001

Effects of nebivolol on human platelet aggregation.

It has been documented that beta-adrenergic antagonists can influence platelet aggregation by a mechanism independent of their ability to antagonize beta-adrenoceptors. Nebivolol, a selective beta1-adrenergic receptor antagonist with additional hemodynamic effects, is able to vasodilate human forearm vasculature by acting on the L-arginine/nitric oxide pathway. Constitutive nitric oxide synthase is present also in human platelets, resulting in the formation of nitric oxide, an endogenous inhibitor of platelet aggregation. The aim of this study was to investigate the effects of nebivolol on platelet aggregation and in particular to determine the involvement of the platelet L-arginine/nitric oxide pathway. Propranolol, a nonselective beta-adrenergic antagonist, and carvedilol, a beta-blocker with vasodilating properties, were compared with nebivolol on platelet activity. Plasma from healthy male subjects was used. Platelet aggregation was achieved with adenosine diphosphate (ADP) (3 microM) and collagen (1 microg/ml), using the Born turbidimetric method to measure platelet aggregation. Our results showed that nebivolol, propranolol, and carvedilol all had an inhibitory effect on both ADP- and collagen-induced platelet aggregation. Nebivolol exhibited the greatest inhibition effect on platelet aggregation. The mechanism responsible for the inhibitory effect of nebivolol appeared to involve a nitric oxide-dependent pathway. Indeed, L-arginine augmented the inhibitory effects of nebivolol on platelet aggregation induced by collagen and ADP. Furthermore, the inhibitory effect of nebivolol on platelet aggregation was reduced in the presence of the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA). In conclusion, we have demonstrated in this study that nebivolol's mechanism of platelet aggregation inhibition differs from that of other beta-adrenergic antagonists by being partially dependent on nitric oxide production.

Adenosine Diphosphate↗
PubMed2001

Molecular typing and long-term comparison of clostridium difficile strains by pulsed-field gel electrophoresis and PCR-ribotyping.

Thirty-two related and 68 unrelated isolates of Clostridium difficile, isolated in different Italian hospitals since 1987, were analysed by PFGE and PCR-ribotyping to investigate their genetic relatedness. The isolates were classified into 28 groups by PFGE and 20 ribotypes by PCR-ribotyping. A single clone of C. difficile was recognised as the cause of three geographically and chronologically distant outbreaks. The correlation between PFGE and PCR-ribotyping results was good, with agreement for 77 (84%) of the 92 isolates typed by both methods. However, among sporadic isolates the discriminatory power of PFGE was more evident. Eight isolates that were untypable by PFGE could be analysed by PCR-ribotyping. The dendrograms generated showed that the genetic relatedness of the C. difficile isolates obtained by both techniques was comparable. The majority of the isolates in recent years appeared to be genetically unrelated to isolates from past infections. However, two clonal groups identified in all time periods had a common origin and this seems to indicate that they share some advantageous biological characteristics. The constant monitoring of C. difficile epidemiology will allow acquisition of further important data on this nosocomial pathogen.

Clostridioides difficile↗
PubMed2001

The action of acetyl-L-carnitine on the neurotoxicity evoked by amyloid fragments and peroxide on primary rat cortical neurones.

The amyloid beta-peptides have been implicated in the excitotoxic mechanism of neuronal injury in the pathogenesis of Alzheimer's disease. In this paper we examine the effect of different amyloid fragments (beta A1-40, A1-28, and A25-35), as well as potential neuroprotective compounds on rat cortical neuron viability. Exposure of neurones to beta A25-35 or A1-40 at concentrations as low as 1 microgram/ml inhibited, significantly, the MTT response and this level of inhibition was similar after 24-h or three-day exposure. Furthermore, the level of inhibition was not affected by the presence or absence of 5% horse serum in the medium. Preexposure (10 min) of neurones to ALC at concentrations of 0.1, 1, 5, and 10 mM attenuated the inhibition of the MTT response caused by beta A25-35 (50 micrograms/ml) in serum free medium for 24 h. The treatment of cells with vitamin E (100 microM), catalase (4 mg/ml), NGF (0.1 and 10 ng/ml), or cycloheximide (0.1 microgram/ml) significantly restored the MTT response that was inhibited by beta A25-35. The mechanism for the protective actions of these compounds against beta A25-35 toxicity is not clear but may involve free radical scavenger action and preservation of energy production, although other mechanisms, especially for ALC, such as a direct effect on A-beta interaction with charged anionic phospholipids and/or stabilizing action on membranes, are also possible.

Acetylcarnitine↗
PubMed2001

Brain temperature, body core temperature, and intracranial pressure in acute cerebral damage.

OBJECTIVES: To assess the frequency of hyperthermia in a population of acute neurosurgical patients; to assess the relation between brain temperature (ICT) and core temperature (Tc); to investigate the effect of changes in brain temperature on intracranial pressure (ICP). METHODS: The study involved 20 patients (10 severe head injury, eight subarachnoid haemorrhage, two neoplasms) with median Glasgow coma score (GCS) 6. ICP and ICT were monitored by an intraventricular catheter coupled with a thermistor. Internal Tc was measured in the pulmonary artery by a Swan-Ganz catheter. RESULTS: Mean ICT was 38.4 (SD 0.8) and mean Tc 38.1 (SD 0.8) degrees C; 73% of ICT and 57.5% of Tc measurements were > or =38 degrees C. The mean difference between ICT and Tc was 0.3 (SD 0.3) degrees C (range -0.7 to 2.3 degrees C) (p=0. 0001). Only in 12% of patients was Tc higher than ICT. The main reason for the differences between ICT and Tc was body core temperature: the difference between ICT and Tc increased significantly with body core temperature and fell significantly when this was lowered. The mean gradient between ICT and Tc was 0.16 (SD 0.31) degrees C before febrile episodes (ICT being higher than Tc), and 0.41 (SD 0.38) degrees C at the febrile peak (p<0.05). When changes in temperature were considered, ICT had a profound influence on ICP. Increases in ICT were associated with a significant rise in ICP, from 14.9 (SD 7.9) to 22 (SD 10.4) mm Hg (p<0.05). As the fever ebbed there was a significant decrease in ICP, from 17.5 (SD 8.62) to 16 (SD 7.76) mm Hg (p=0.02). CONCLUSIONS: Fever is extremely frequent during acute cerebral damage and ICT is significantly higher than Tc. Moreover, Tc may underestimate ICT during the phases when temperature has the most impact on the intracranial system because of the close association between increases in ICT and ICP.

Adult↗
PubMed2001

Antibiotic prophylaxis and treatment of surgical abdominal sepsis.

The incidence of surgical abdominal sepsis is related to the operation, patient and skill of the surgeon, ranging from <2-3% for laparoscopic cholecystectomy to >35-40% in overt peritonitis. Aged, obese, diabetic, neoplastic, acute patients have the highest incidence of sepsis. Antibiotic prophylaxis significantly reduces the incidence of postoperative infections for Class II and II operations. The proper timing (30-60 min before incision), choice of antibiotic (related to possible pathogens) and correct duration are essential. Ultra-short prophylaxis (only one administration) may be effective in most class II procedures and a cephalosporin can be used. Class II operations (colorectal) may require a booster dose soon after surgery or during surgery exceeding 3 h. The most effective regimen may include: ampicillin, clindamycin, I- II- III- or IV-generation cephalosporins, amoxycillin, aminoglycosides, metronidazole have been used alone and in combination. Combination prophylaxis should be active against aerobic and anaerobic bacteria. Treatment of surgical abdominal sepsis may be primary, seconday or tertiary. Surgery should remove the pathologic lesion, and antibiotics reduce the general effects of sepsis and infectious complications. This article presents information on the general rules for correct prophylaxis and treatment.

Abdomen↗
PubMed2001

Radiofrequency thermal ablation of hepatocellular carcinoma: using contrast-enhanced harmonic power doppler sonography to assess treatment outcome.

OBJECTIVE: We evaluated the accuracy of contrast-enhanced harmonic power Doppler sonography in assessing the outcome of radiofrequency thermal ablation of hepatocellular carcinoma. SUBJECTS AND METHODS: Fifty patients with 65 hepatocellular carcinoma nodules (1-5 cm in diameter; mean diameter, 2.5 cm) were studied using unenhanced and contrast-enhanced harmonic power Doppler sonography before and after IV administration of a microbubble contrast agent. The examinations were repeated after treatment of the tumors with radiofrequency ablation. Findings of the Doppler studies were compared with those of dual-phase helical CT, which were used as points of reference for assessing treatment outcome. RESULTS: Before radiofrequency treatment, intratumoral blood flow was revealed by unenhanced power Doppler sonography in 48 (74%) of 65 hepatocellular carcinoma nodules. After injection of the contrast agent, intratumoral enhancement was observed in 61 (94%) of 65 hepatocellular carcinomas (p < 0.01). After radiofrequency treatment, all 51 (84%) of the 61 hepatocellular carcinomas found to be necrotic on helical CT scans failed to show enhancement on power Doppler sonograms. In nine of the 10 lesions that showed a residual viable tumor on helical CT scans, persistent intratumoral enhancement-matching the enhancing areas on helical CT images-was revealed by power Doppler sonography. These nine hepatocellular carcinomas were subjected to repeated radiofrequency thermal ablation with the guidance of contrast-enhanced power Doppler sonography. Complete necrosis was seen after the second treatment session in six of the nine lesions. CONCLUSION: Contrast-enhanced harmonic power Doppler sonography is an accurate technique for assessing the outcome of radiofrequency thermal ablation of hepatocellular carcinoma and may be useful in guiding additional treatment in patients with incomplete response to initial efforts.

Aged↗
PubMed2001

Competition for space among sessile marine invertebrates: changes in HSP70 expression in two Pacific cnidarians.

The role of stress proteins-either constitutive (HSC) or inducible (HSP)-of the HSP70 family in intra- and interspecific competition for space was examined in two sessile Pacific cnidarians. Anthopleura elegantissima, an intertidal anemone, and Corynactis californica, a subtidal corallimorpharian, express HSP70 in the absence of apparent physical stress. HSP70 protein expression is concentrated in the tentacles of A. elegantissima when the animal is exposed to contact with other benthic organisms. Under the same conditions, however, HSP concentrations are similar in the body and tentacles of C. californica. When two different clones of A. elegantissima interact in the field, the outside polyps (warriors) express more HSP70 than the inside ones (2.4 versus 0.6 ng HSP70/microg Protein). When different C. californica clones interact, HSP70 expression in the outside and inside polyps is similar (1.5 versus 1.8 ng HSP70/microg P) and is fairly constant in the corallimorpharian in the different interspecific encounters. HSP70 expression is related to the different kinds of aggression encountered by both cnidarians. HSP70 expression may be involved in the recovery of tissues damaged by the allelochemical, cytotoxical, or corrosive substances produced by different enemies. C. californica clones appear prepared for war, as evidenced by the high constant expression of HSP70 in the polyps. A. elegantissima exhibits differential HSP70 expression depending on the identity of each neighboring intra- or interspecific sessile competitor. We propose that stress proteins can be used to quantify space competition or aggression among sessile marine invertebrates.

Agonistic Behavior↗
PubMed2001

[Magnetic resonance imaging in the evaluation of parametrial invasion of carcinoma of the cervix uteri: optimization of the study protocol].

PURPOSE: To determine the efficacy of three different MR sequences in the evaluation of parametrial invasion by early-stage cervical cancer. MATERIAL AND METHODS: Eighteen consecutive patients with cervical cancer clinically assessed as stage IB1 underwent MR imaging examination with the use of the following sequences: FSE T2-weighted, FSE fat-suppressed T2w, and SE fat-suppressed Gadolinium-enhanced T1w. In all cases, the presence or absence of parametrial invasion on both sides per each sequence used was evaluated. Subsequently all the sequences have been considered together for the evaluation of tumor invasion. Gold standard of the study was the histopathologic analysis of the surgical specimens. RESULTS: At histological examination, parametrial invasion by tumor was found in 6 out of 36 parametria evaluated. The accuracy achieved with each of the sequences used was as follows: 94% with FSE T2w; 86% with FSE fat-suppressed T2w; and 67% with SE fat-suppressed Gadolinium-enhanced T1w. The simultaneous evaluation of all 3 sequences obtained an accuracy level similar to that achieved with FSE T2w. The difference between the accuracy of T2w sequences and that of fat-suppressed contrast-enhanced T1w sequences was statistically significant (p<0.01). DISCUSSION AND CONCLUSIONS: Our data suggest that the MR imaging protocol for the evaluation of parametrial tumor invasion could be restricted to FSE T2w sequences. These proved to have the highest negative predictive value (97%) which allows a reliable selection of patients who can be surgically treated.

Adenocarcinoma↗
PubMed2001

Factors affecting biodegradation of 2-chlorophenol by Alcaligenes sp. in aerobic reactors.

The influence of variations in carbon source concentration, cell inocula, pH, presence of other substrates, and other organisms on the biodegradation of 2-chlorophenol (2-CP) was studied for Alcaligenes sp. isolated from natural sources. Assays of biodegradation were performed in batch and continuous-flow fluidized-bed aerobic reactors. Evaluation of biodegradation was performed by determining total phenols, chemical oxygen demand (COD), and 2-CP by ultraviolet (UV) spectrophotometry. Measurement of microbial growth was carried out by the plate count method. Bioassays of acute toxicity were performed to evaluate detoxification by using Daphnia magna. Results obtained show that under batch conditions with initial inocula of 10(6) cells/mL the strain grew exponentially with 100, 200, and 300 mg/L of 2-CP within 48 hr. A lag period was observed with low cell density inocula (10(5) cells/mL). The strain showed marked delay in the biodegradation of 2-CP at pH 5. Removal of target substrate from mixtures containing other carbon sources demonstrated the possibility of concurrent growth. Mineralization of 2-CP was assessed by gas chromatography carried out at the end of the batch assays and at the exit of the continuous-flow reactor. The presence of other organisms (bacteria, rotifers, ciliate, and algae) that developed in the fluidized-bed reactor did not affect the efficacy of the biodegradation of 2-CP. The removal of 2-CP in the two assayed systems was over 97% in all cases. Toxicity was not detected at the exit of the continuous reactor.

Alcaligenes↗
PubMed2001

[Drugs interfering with somatostatin receptors].

The use of drugs interfering with somatostatin receptors (ssR) is now consolidated practice in diagnostics and therapy, stimulating the development of new and more efficient molecules offering improved pharmacodynamics. Over the years, we have passed from the use of native somatostatin to mini-somatostatin and then octapeptides, above all octreotide. Subsequently, peptides were synthesized with specific affinities for a single receptorial subtype, like compound BIM23268 and compound CH275. More recently, somatostatin analogs were synthesized with a non-peptide structure. Another important aspect in the history of sst analogs is represented by the development of new pharmaceutical formulas for these drugs in order to improve patient compliance by reducing dose frequency.

Animals↗