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Biomedical subjects

G Marchiori

Publications and source records attributed to G Marchiori.

17 recordsLinked to original sources
PubMed2006

Active-feedback control of the magnetic boundary for magnetohydrodynamic stabilization of a fusion plasma.

Stable operation with control on magnetohydrodynamic modes has been obtained in the modified reversed field experiment employing a set of 192 feedback controlled saddle coils. Improvements of plasma temperature, confinement (twofold), and pulse length (threefold) and, as a consequence of the magnetic fluctuation reduction, strong mitigation of plasma-wall interaction and mode locking are reported.

Journal Article↗
PubMed2004

Feedback stabilization of multiple resistive wall modes.

Active feedback stabilization of multiple independent resistive wall modes is experimentally demonstrated in a reversed-field pinch plasma. A reproducible simultaneous suppression of several nonresonant resistive wall modes is achieved. Coupling of different modes due to the limited number of the feedback coils is observed in agreement with theory. The feedback stabilization of nonresonant RWMs also has an effect on tearing modes that are resonant in the central plasma, leading to a significant prolongation of the discharge pulse.

Journal Article↗
PubMed2004

Precision and accuracy of the bedside examination in detecting an ejection fraction of less than 40% following acute myocardial infarction.

BACKGROUND: Left ventricular function is the most important determinant of prognosis following myocardial infarction. METHODS: A prospective analytical cohort study of 33 cardiac care unit survivors of acute myocardial infarction was performed to assess the accuracy, reproducibility and observer variation of the bedside Valsalva response in predicting an ejection fraction (EF) less than 40%. RESULTS: Agreement between physicians for the clinical Valsalva response was excellent (kappa coefficient 0.75), as was the comparison between physicians' clinical response to the Finapres (Ohmeda, USA) hemodynamic response (weighted kappa=0.85). The EF was significantly higher among patients with a normal Valsalva response (56.9%) than in patients with either an absent overshoot (48.4%) or a square wave (28.3%) response (P<0.001). Physicians were very accurate at estimating whether the EF was greater or less than 40%. In 40 of 66 situations, the clinicians were confident, based on the clinical examination and the Valsalva response, that the EF was either greater or less than 40%. In these situations, agreement (95.0%) and kappa (0.89) were both excellent. When all patients were considered, the degree of agreement (90.8%) and kappa (0.80) diminished slightly. A square wave response had poor sensitivity (37.5%) but excellent specificity (92.7%), whereas any abnormal response had excellent sensitivity (91.7%) but poor specificity (54.8%). CONCLUSION: Compared with many other aspects of the clinical examination, the bedside Valsalva manoeuvre has acceptable degrees of interobserver variability. A normal response tends to rule in an EF of greater than 40%, whereas a square wave response rules out an EF of greater than 40%. This simple bedside manoeuvre may be useful in predicting low EF following acute myocardial infarction.

Adult↗
PubMed2004

Biological qualification of blood units: considerations about the effects of sample's handling and storage on stability of nucleic acids.

BACKGROUND: In transfusional setting introduction of nucleic amplification technique (NAT) for HBV-DNA, HCV-RNA and HIV-RNA in biological qualification of blood units suggest some problems. At first the opportunity to operate on mini-pool, at second the need to store the samples at +4 degrees C. The authors therefore have tried to estimate the impact of these conditions on the operativity of NAT testing in the transfusional setting. METHODS: The following parameters has been estimated: distribution of viral-load in untreated subjects, stability of nucleic acids during storage at +4 degrees C, stability of nucleic acids after repeated cycles of freezing and defrosting, robustness of the test to the cross-contamination, definition of the detection-limit (95%). Quantitative tests has been performed by using the following kits: Cobas Amplicor HBV Monitor, Cobas Amplicor HCV Monitor, Cobas Amplicor HIV Monitor; the qualitative tests has been performed by using the following kits: Ampliscreen HBV, Ampliscreen HCV 2,0, Ampliscreen HIV 1,5 all supplied by Roche Molecular System (Brancburg, NJ). RESULTS: Viral load in untreated subjects showed wide variation for HBV, HCV and HIV. HBV has been demonstrated much stable to the conservation +4 degrees C also until 168 h while for HCV and HIV a greater decrease of the viral-load was observed. For all and three virus the conservation to +4 degrees C until 72 h does not seem to involve meaningful fall in the viral-load. A remarkable reduction of the viral-load has been observed after five cycles of freezing and defrosting. All the tests showed a good robustness to cross-contamination. The detection-limit (95%) was 8 U/ml for HBV, 21 U/ml for HCV and 27 copy/ml for HIV. CONCLUSIONS: Samples for NAT testing, can be stored until 72 h to +4 degrees C without appreciable lowering of the viral-load. Repeated cycles of changes of state should be avoided. The tests showed a good robustness to cross-contamination. NAT tests for biological qualification of blood units had a minimal sensibility around 50 (copy/unit/ml). In our experience the detection-limit (95%) was 21 U/ml for HCV, 27 copies/ml for HIV, 8 U/ml for HBV. The availability of NAT test for HBV-DNA, HCV-RNA e HIV-RNA, sensitive and reliable, together with epidemiological data, suggest the opportunity to place side by side, in the biological qualification of the blood units, to add the tests for HBV-DNA and HIV-RNA to the test for HCV-RNA mandatory by low, in Italy in the biological qualification of blood units.

Blood Preservation↗
PubMed2002

[Foetal-maternal alloimmunizations in the South-East area of the Venice province].

BACKGROUND: This study report the results obtained in a retrospective analysis of the foetal-maternal alloimmunizations observed from 1993 to 1999 in the South-East area of the Venice province. METHODS: The data concerning 17,000 pregnancy observed in this area from 1993-1999 have been collected. For each pregnancy data concerning maternal ABO, Rh, Kk and IAT as well as foetal ABO, Rh, Kk and DAT were available. Further data (mainly antibodies concentration and specificity) were available if a foetal-maternal alloimmunization was detected and if transfusional support was given after the birth. RESULTS: The authors observed 465 alloimmunizations (prevalence 2.7%): 381 (82%) of these were due to an ABO foetal-maternal incompatibility, 23 due to D incompatibility and the other 61 due to other blood groups antigens. Only 6 cases needed transfusional support: 5 exchange transfusion (a patient needed 2 exchanges) and a delayed transfusion. CONCLUSIONS: Foetal-maternal alloimmunizations are today a rare but not exceptional event (about 3% of pregnancy), the great majority of these alloimmunizations are due to an ABO incompatibility. Despite the prevention of alloimmunization in D negative women by using Rh immune globulin, anti-D alloimmunization is still observed. A great number of other blood groups antigens are involved in foetal-maternal alloimmunization mainly within the Rh system (CcEe, etc.). In the authors' experience the great majority of foetal-maternal alloimmunizations were clinically silent, only 6 cases (1.3% of patients with a positive DAT) needed transfusional therapy.

ABO Blood-Group System↗
PubMed2001

Pulsatile hemodynamics in congestive heart failure.

Pulse pressure, an indirect measure of vascular stiffness and pulsatile load, predicts clinical events in congestive heart failure (CHF), suggesting that abnormal pulsatile load may contribute to CHF. This study was designed to assess more direct measures of central pulsatile load in CHF. Noninvasive hemodynamic evaluations were performed in 28 subjects with CHF and 40 controls using calibrated tonometry of the brachial, radial, femoral, and carotid arteries along with echocardiographic assessment of left ventricular outflow tract (LVOT) diameter and Doppler flow. Characteristic impedance (Z(c)) was calculated as the ratio of DeltaP (carotid) and DeltaQ (LVOT flow) in early systole. Carotid-radial (CR-PWV) and carotid-femoral (CF-PWV) pulse wave velocities were calculated from tonometry. Augmentation index was assessed from the carotid waveform. Total arterial compliance (TAC) was calculated using the area method. Brachial pulse pressure was elevated (62+/-16 versus 53+/-15 mm Hg, P=0.015) in CHF because of lower diastolic pressure (66+/-10 versus 73+/-9 mm Hg, P=0.003). CHF had higher Z(c) (225+/-76 versus 184+/-66 dyne. sec. cm(-5), P=0.020). CF-PWV did not differ (9.7+/-2.7 versus 9.2+/-2.0, P=0.337), whereas CR-PWV was lower in CHF (8.6+/-1.4 versus 9.4+/-1.5, P=0.038). There was no difference in TAC (1.4+/-0.5 versus 1.4+/-0.6 mL/mmHg, P=0.685), and augmentation index was lower in CHF (8+/-17 versus 21+/-13%, P=0.001). CHF subjects have elevated central pulsatile load (Z(c)), which is not apparent in global measures such as augmentation index or TAC, possibly because of contrasting changes in central and peripheral conduit vessels. This increased pulsatile load represents an important therapeutic target in CHF.

Arteries↗
PubMed2000

The stability of hepatitis C virus RNA after storage at +4 degrees C.

One of the major issues in nucleic acid testing is how to store blood samples to obtain reliable results. We therefore studied hepatitis C virus (HCV) RNA concentration in samples after storage at +4 degrees C or freezing and thawing. Six HCV RNA-positive, untreated subjects were studied. Blood samples were collected from these subjects in plasma preparation tubes. The HCV RNA concentration was analysed after storage at +4 degrees C for 168 h or after five freeze-thaw cycles. For HCV RNA quantification we used a qualitative and a quantitative commercial test. After 168 h of storage at +4 degrees C, the HCV RNA concentration was similar to that observed at time-point 0 (5.025 log vs 5.492 log). In one sample we observed a significant fall in HCV RNA concentration. After five freeze-thaw cycles, the HCV RNA concentration was lower than that observed at time-point 0 (4.454 log vs 5.492 log) and in four samples we observed a significant fall in HCV RNA concentration. Our data suggest that HCV RNA is stable in whole blood samples stored at +4 degrees C for 168 h. Based on our results, we conclude that the standard procedures for transport of blood samples (at room temperature for a maximum of 5 h) and storage schedules (+4 degrees C for a maximum of 48 h) can be maintained without compromising the quality of results.

Blood Donors↗
PubMed1998

Malignant meningeal melanoma.

We report the case of an isolated pigmented lesion of the cerebellar tentorium which was initially interpreted as meningeal melanocytoma. The immunohistochemical study required as a result of a subsequent post-surgical recurrence prompted us to reconsider the early diagnosis in favour of malignant meningeal melanoma. On the basis of data in the literature, the possibility that the lesion may have been a dural melanoma is discussed.

Aged↗
PubMed1994

[Retroperitoneal ganglioneuroma. A case report and review of the literature].

Ganglioneuromas are typically of slow growth and benign evolution and may remain clinically silent for a considerable time if favourably situated. Many large examples are discovered incidentally on X-ray examination, routine abdominal palpation or at necropsy. Ganglioneuromas are often encountered in childhood and are found more frequently in the posterior mediastinum than in any other single situation; other sites are the lumbar and pelvic retroperitoneal tissues, the gastrointestinal tract and the mesentery. Diffuse alimentary tract ganglioneuromatosis has been described as port of the multiple endocrine neoplasia syndrome (MEN) type II-B. Sometimes ganglioneuromas are found in the von Recklinghausen Syndrome. The authors report in this paper a rare case of a retropancreatic ganglioneuromas.

Female↗
PubMed1993

Category-specific form-knowledge deficit in a patient with herpes simplex virus encephalitis.

In-depth case study of a herpes simplex virus encephalitis patient who presents with a relatively clear knowledge disorder and anterograde amnesia in the absence of any other major cognitive deficit. The main neuropsychological feature is a category-specific impairment restricted to living things. The patient misnamed pictures of animals and vegetables, could not accurately draw animals from memory or verbally describe their visual appearance, and was not accurate in sorting pictures of real animals from pictures of unreal animals; conversely, in the same tasks her performance with artifactual objects was either errorless or superior to that with animals. We interpret the patient's category-specific deficit as due to a selective disturbance within the structural description system, rather than a deficit in low-level visual processing or semantic memory. From this case study and a review of other reported cases we claim that such deficit of form-knowledge is a consequence of the extensive lesions that affect bilaterally the inferior parts of the temporal lobes. The patient here described thus offers further empirical evidence for the crucial role of the inferotemporal cortex in processing visual knowledge about concepts.

Acyclovir↗
PubMed1989

Kinematic measurement from panned cinematography.

Traditional 2-D cinematography has used a stationary camera with its optical axis perpendicular to the plane of motion. This method has constrained the size of the object plane or has introduced potential errors from a small subject image size with large object field widths. The purpose of this study was to assess a panning technique that could overcome the inherent limitations of small object field widths, small object image sizes and limited movement samples. The proposed technique used a series of reference targets in the object field that provided the necessary scales and origin translations. A 102 m object field was panned. Comparisons between criterion distances and film measured distances for field widths of 46 m and 22 m resulted in absolute mean differences that were comparable to that of the traditional method.

Humans↗