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Biomedical subjects

R Ruggeri

Publications and source records attributed to R Ruggeri.

At least 19 recordsLinked to original sources
PubMed2004

Unexpected behavior of crossing microwave beams.

An anomalous effect in the near field of crossed microwave beams, consisting in an unexpected transfer of modulation from one beam to the other, cannot be fully interpreted, at least not in a simple way, in terms of the usual electromagnetic or related framework. It is hypothesized that a local breaking of the Lorentz invariance, already invoked for an alternative interpretation of superluminal behaviors in these kinds of systems, could provide a partial explanation of the present results, although other interpretations cannot be completely ruled out.

Journal Article↗
PubMed2003

Tunneling as a stochastic process: a path-integral model for microwave experiments.

Delay time results obtained in microwave experiments at frequencies above and below the cutoff frequency of different waveguide sections are interpreted on the basis of wave propagation in the presence of dissipative effects. Kac's original suggestion was the starting point for the formulation of a stochastic model, which has now been substantially improved, also in relation to the transition-elements theory of Feynman-Hibbs. In this way, an approach to the problem is provided, which is completely distinct from the ones formulated elsewhere.

Journal Article↗
PubMed2002

Anomalous delay in wave propagation and tunneling: a transition-elements analysis of the traversal time.

An alternative model for near-field propagation and optical tunneling is proposed following the lines of the path-integral method developed by Feynman, and in particular by using a transition-elements analysis. Such a model was able to account for the frequency dependency of delay-time results of an experiment involving microwave propagation in the near field using two horn antennas [A. Ranfagni et al., Phys. Rev. E 66, 036111 (2002)]. Furthermore, this approach is also capable of interpreting delay-time results as a function of the barrier width in a frustrated total internal reflection experiment performed at the microwave scale and in the optical region.

Journal Article↗
PubMed2002

Anomalous pulse delay in microwave propagation: A stochastic process interpretation.

An experiment involving microwave propagation in the near-field region with two horn antennas demonstrated a superluminal behavior which is strongly dependent on the frequency. The models previously proposed are found to be inadequate for interpreting the results. An attempt is made within the framework of a stochastic model, which can be improved by a path-integral analysis.

Journal Article↗
PubMed2002

Different approach for evaluating dissipation in macroscopic quantum tunneling.

The problem of evaluating dissipative effects in macroscopic quantum tunneling is re-examined for the case of Josephson junctions, with the adoption of an alternative way with respect to several previously proposed and, in some cases, contradictory approaches. The system, which consists of a junction coupled to a transmission line, is analyzed both analytically and numerically. A test of the theoretical model, as compared to the experimental results available, is performed in accordance with a criterion based on a shortening of the traversal time.

Journal Article↗
PubMed2002

Simple stochastic model for optical tunneling.

A simple model, derived from a Brownian-motion scheme, is capable of interpreting the results of delay-time measurements relative to frustrated total reflection experiments at the microwave scale but also in the visible region. In this framework we also obtain a plausible description of the trajectories (rays) inside the tunneling region, the air gap between two paraffin prisms.

Journal Article↗
PubMed2001

Experimental evidence of tunneling as a stochastic process.

A model for tunneling based on stochastic processes proves to be capable of interpreting the results of two experiments at the microwave scale. The first of these consisted of measuring the penetration time in a subcutoff waveguide; the second one, in measuring the shift of a beam in a frustrated total reflection. Said shift which is a measurement of the traversal time of the barrier. In both cases, a peak in the real-time component was evidenced, as predicted by the theoretical model.

Journal Article↗
PubMed2001

Piver's radical hysterectomy (type III): Endo-Gia 30 stapler versus traditional forcipressure for resection of the cardinal ligament.

OBJECTIVE: Morbidity and costs associated with Piver's radical hysterectomy (type III) are noteworthy. The Endo-Gia stapler method for resection of cardinal ligaments can reduce duration of surgery and hospitalization, blood loss, costs and postoperative infection rates. METHOD: Two groups of patients (homogeneous for age, weight and medical condition) were studied: one group was operated on using the Endo-Gia stapler method (n=52) and the other with the traditional forcipressure (n=13). The size of parametrial tissue removed, blood loss, duration of surgery, duration of hospitalization, cost of materials and postoperative fever were compared in the two groups. RESULT: Mean operative times were lower in the Endo-Stapler group than in the controls (mean 180 min versus 220 min). Mean blood loss was 300 cc in the stapler group versus 450 cc in the forcipressure group. Mean cost of surgery (considering costs of materials, hospital stay. duration of surgery), was lower in the stapler group (3,095 euros) than in the group who underwent traditional surgery (3,434 euros). CONCLUSION: Our data suggest the Endo-Gia stapler method significantly reduces blood loss, operative time and cost.

Adult↗
PubMed2000

Observation of superluminal behaviors in wave propagation

The possibility of observing superluminal behavior in the propagation of localized microwaves over distances of tens of wavelengths is experimentally demonstrated. These types of waves, better than the evanescent modes of tunneling, can contribute to answering the question on the luminal limit of the signal velocity.

Journal Article↗
PubMed1999

Chemokine production by human chondrocytes.

OBJECTIVE: To evaluate the role of chondrocytes in producing CXC chemokines [interleukin 8 (IL-8), growth related gene product (GRO-alpha)] and CC chemokines [monocyte chemoattractant protein (MCP-1), macrophage inflammatory protein (MIP-1alpha), RANTES] in patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and subjects after traumatic injury (PT). METHODS: Articular cartilage specimens were obtained from 38 patients with OA and 18 with RA undergoing joint replacement surgery. Healthy human cartilage was obtained from femoral condyles removed after trauma in 11 subjects with no history of joint pathology (PT cases). Chondrocytes were isolated from articular cartilage by sequential enzymatic digestion and cultured in vitro. Chemokine production was investigated in unstimulated condition and after 72 h incubation with proinflammatory [IL-1beta, tumor necrosis factor-alpha (TNF-alpha)] and antiinflammatory [transforming growth factor-beta1 (TGF-beta1), IL-10] mediators. Chemokine concentrations in cell supernatants were evaluated by ELISA. RESULTS: Chondrocytes produce all these chemokines to a different extent. IL-1beta was a more potent stimulus than TNF-alpha in inducing production of all chemokines except MCP-1. We found no statistical differences among chondrocytes isolated from OA, RA, and PT for chemokine production in either basal conditions or after cytokine stimulation. IL-1beta induced chemokine production can be modulated by TGF-beta1 in different ways according to the various chemokines, while IL-10 does not affect IL-1beta induced chemokine production. CONCLUSION: Chondrocytes produce IL-8, GRO-alpha, MCP-1, MIP-1alpha, and RANTES. Proinflammatory factors (IL-1beta, TNF-alpha) effectively upregulate chemokine production, but production is scarcely modulated by the antiinflammatory mediators TGF-beta and IL-10. Chondrocyte derived chemokines may play a role in triggering the mechanisms involved in pathogenesis and persistence of joint diseases.

Adult↗
PubMed1998

Serum chemokines in patients with psoriatic arthritis treated with cyclosporin A.

OBJECTIVE: To evaluate the levels of serum chemokines in patients with psoriatic arthritis (PsA) before and during cyclosporin A (CyA) treatment. METHODS: Sixteen outpatients with active PsA were followed for 6 months during low dosage CyA treatment. Serum chemokines of the C-X-C and C-C groups were determined by ELISA at the baseline. Serum RANTES levels were measured at 2 month intervals for 6 months. Serum chemokine levels were related with clinical and laboratory disease activity variables. RESULTS: Serum interleukin 8 and macrophage inflammatory protein 1alpha levels were undetectable at baseline. Mean serum growth related gene product-alpha and monocyte chemoattractant protein 1 values were reduced and serum RANTES were elevated compared to controls. CyA treatment did not change serum RANTES levels. Patients with PsA with persistently normal serum RANTES levels (4 patients) had a more favorable clinical and laboratory response to CyA compared to patients with persistently high serum levels (6 patients). CONCLUSION: Serum RANTES levels are higher in patients with PsA than in a control population. CyA treatment does not change RANTES values. Patients with PsA with persistently normal RANTES levels have a better response to CyA treatment.

Adult↗
PubMed1997

Urinary excretion of ethylenethiourea in five volunteers on a controlled diet (multicentric study).

Urinary excretion of ethylenethiourea (ETU) was monitored for 8 days in a group of five male non-smoker volunteers on a diet, the items of which were assayed for ETU and carbon sulphide. Urinary excretion of ETU reflected the consumption of wine, fruit and vegetables. Urinary ETU concentrations ranged from 0.6 to 6.7 micrograms/g creatinine. ETU concentrations in the food eaten by the volunteers were generally below the detection limit whereas in wine 8.8 micrograms/l ETU was detected. Evolution of carbon sulphide by food samples ranged from 0.03 to 0.17 mg/kg. Mean (+/- S.D.) daily intake of ETU in wine was 3.5 +/- 0.2% of the acceptable daily intake (ADI): 0.070 +/- 0.004 micrograms/kg body wt. During the 8 days of the study, an average of 48.3% of the ETU ingested in wine was excreted unmodified by the kidneys. Twenty-four hour urinary excretion of ETU was significantly correlated with daily intake of ETU (r = 0.768) and CS2 evolved by the daily food items (r = 0.414).

Adult↗
PubMed1997

[The estimation of the absorbed dose with wedge fields].

In the dose calculation at an arbitrary point in a water-equivalent homogeneous medium irradiated by an X-ray megavoltage wedged beam (w), several treatment planning systems (TPS) based on the Bently-Milan data processing procedure use algorithms which do not distinguish between wedged OF(s)w and open OF(s)o output factor or between field size dependent WF(s) and not WF wedge factor. This is equivalent to neglecting the difference between open (o) and wedged (w) fields both in relation to back-scattered radiation from secondary collimators to the beam monitor chamber and to scattered radiation generated by the water-phantom at the depth of measurement. The output factor can be expressed by: OF(s) = Sc(s)* Sp(s) where Sc(s) is the collimator scatter factor and Sp(s) is the phantom scatter factor. The approximation between wedged OF(s)w and open OF(s)o is thus equivalent to ignoring the fact that the insertion of the wedge in an open field modifies the back-scattered radiation from secondary collimators to the beam monitor chamber and the scattered radiation in the phantom. The lack of wedge factor's field size dependence WF(s) or the equivalent lack of wedged field output factor OF(s)w in the beam data installed in TPS is in appreciable source of systematic error in the calculation of the absorbed dose. This systematic uncertainty can be evaluated by measuring the wedge factor's field size dependence. In our study of WF(s) for 25-MV X-rays generated by our Linac "Saturne-43" (by GE), the relative wedge factor variation with respect to the reference value WF(so) ranges from (-.7%) for the smallest wedged field size (5 x 5) cm2 to (+2.6%) for the largest wedged field size (20 x 20) cm2. It is clear that the same relative variation reproduces itself identically as a systematic uncertainty in the calculation of the absorbed dose.

Absorption↗
PubMed1996

Reference values of urinary ethylenethiourea in four regions of Italy (multicentric study).

The results of a study in which urinary ethylenethiourea (ETU) was assayed in the general population (167 subjects) of four Regions of Italy (Veneto, Lombardy, Piedmont and Trentino Alto Adige) are reported. The results are compared with those in a population of 97 subjects from Rovescala, a hillside wine-producing town a few kilometers from Pavia, where ethylenebisdithiocarbamates are sprayed by helicopter. It was found that an average of 24% of the populations of the four regions, taken together, had urinary ETU levels above detection limits (1.0 microgram 1(-1)) as compared to 37% of the population of Rovescala. The ranges of concentration were 0.8-8.3 micrograms 1(-1) for the four regions and 0.9-61.4 micrograms 1(-1) for Rovescala. Statistically significant variables for urinary ETU levels were smoking and wine drinking.

Adolescent↗