Strong Reduction of the Effective Radiation Length in an Axially Oriented Scintillator Crystal.

We measured a considerable increase of the emitted radiation by 120 GeV/c electrons in an axially oriented lead tungstate scintillator crystal, if compared to the case in which the sample was not aligned with the beam direction. This enhancement resulted from the interaction of particles with the strong crystalline electromagnetic field. The data collected at the external lines of the CERN Super Proton Synchrotron were critically compared to Monte Carlo simulations based on the Baier-Katkov quasiclassical method, highlighting a reduction of the scintillator radiation length by a factor of 5 in the case of beam alignment with the [001] crystal axes. The observed effect opens the way to the realization of compact electromagnetic calorimeters or detectors based on oriented scintillator crystals in which the amount of material can be strongly reduced with respect to the state of the art. These devices could have relevant applications in fixed-target experiments, as well as in satellite-borne γ telescopes.

Feasibility and diagnostic accuracy of a low radiation exposure protocol for prospective ECG-triggering coronary MDCT angiography.

AIM: To compare the feasibility, accuracy, and effective radiation dose (ED) of multidetector computed tomography (MDCT) in the detection of coronary artery disease using a combined ED-saving strategy including prospective electrocardiogram (ECG) triggering with a short x-ray window and a body mass index (BMI)-adapted imaging protocol using adaptive statistical iterative reconstruction (ASIR; group 1), in comparison with a prospective ECG triggering strategy alone (group 2). MATERIALS AND METHODS: One hundred and seventy patients scheduled for invasive coronary angiography (ICA) were evaluated. Fourteen patients were not eligible for MDCT. The remaining 156 patients were randomized to group 1 (78 patients) and group 2 (78 patients). Eight and 11 patients in groups 1 and 2, respectively, were excluded after randomization because the patients' heart rates were >65 beats/min. MDCT images were assessed for feasibility, signal-to-noise ration (SNR), and contrast-to-noise ratio (CNR), accuracy in detection of coronary stenoses >50% versus ICA and for ED. RESULTS: The feasibility, SNR, CNR, accuracy in a segment-based and patient-based model were similar in both groups (97 versus 95%, 14.5 ± 3.9 versus 14.2 ± 4.1, 16 ± 4.6 versus 16.5 ± 4.4, 95 versus 94% and 97 versus 99%, respectively). The ED in group 1 was 72% lower than in group 2 (2.1 ± 1.2 versus 7.5 ± 1.8 mSv, respectively; p<0.01). CONCLUSIONS: The use of a multi-parametric ED saving protocol results in a significant reduction in ED without a negative impact on accuracy.

Capsaicin-sensitive tachykinin-like immunoreactivity in the thymus of rats and guinea-pigs.

Capsaicin-sensitive, substance P-like immunoreactivity (SP-LI) has been detected recently in rat thymus. Other tachykinins are frequently present with SP. In the present study, tachykinin-like immunoreactivity (TK-LI) was measured in guinea-pig, rat, mouse and hamster thymus with the amount detectable being greatest in guinea-pig, less in rat and least in mouse; it was not detectable in hamsters. In guinea-pig and rat thymus, but not in mouse, TK-LI was markedly reduced by pretreatment with capsaicin. TK-LI levels correlated significantly with those of SP-LI in both guinea-pig and rat thymus. High-performance liquid chromatography (HPLC) fractions considered to represent neurokinin A, eledoisin and neuropeptide K were present in guinea-pig thymus but only the first two were present in rat thymus.

Gonadotropins and inhibins along the development of a luteinized rat ovarian tumor.

Luteinized intrasplenic ovarian tumors develop in response to high circulating gonadotropins. The relationship between tumor development, gonadotropins and inhibins was studied. Tumor-bearing animals were sacrificed weekly along the first 6 weeks of development. Inhibins were measured by enzyme-linked immunosorbent assay (ELISA), serum gonadotropins, GH and IGF-1 by RIA. Inhibin subunit mRNAs were determined by Northern blot. Tumor histology was examined. Ovarian grafts grew significantly along development. LH increased ten-fold on week 1; a further significant increment was observed on week 3. FSH peaked on weeks 1 and 2 and fell significantly thereafter. Serum inhibins markedly increased on weeks 3-5. Tumor inhibin A content and mRNA levels for alpha and beta A subunits also increased on week 3. Inverse correlations between inhibins and FSH and direct correlations between inhibins and LH were observed. Tumor inhibin A and IGF-1 contents correlated significantly. Increasing levels of luteinization were observed along tumor development. These luteinized tumors develop mainly in response to LH, since growth continues under FSH inhibition. The active inhibin secretion and the positive correlation between inhibins and LH suggests that LH may be the main driving force behind this production, while growth factors produced by the gonads may also participate in their regulation.

A photometric method for the dosage of factor XIII applied to the study of chronic hepatopathies.

The photometric method of Fickenscher et al. for the determination of factor XIII (FXIII) activity has been used in the study of 35 patients with severe chronic hepatopathy, in comparison with 25 normal subjects. The FXIII proteic fractions a and b were determined by quantitative immuno-electrophoresis after Laurell. The plasmatic FXIII activity, as well as the proteic fractions a and b, were significantly reduced in hepatopatic patients, in comparison to controls, and proportional to the prolongation of prothrombin times. Ratios between functional and immunological levels of FXIII in hepatopatics were similar to those observed in controls. These results confirm the involvement of fibrin stabilization deficiency in the coagulation defect of severe chronic hepatopathies. The correlations between functional and antigenic values are in agreement with the hepatic origin of FXIII. The method of Fickenscher has been proved to be rapid and simple, and it may be useful in the routine study of hepatopathies, for a better knowledge of the role of FXIII deficiency in the complex coagulopathy of liver diseases, as well as of other acquired FXIII deficiencies.

Coexistence of antithrombin deficiency, factor V Leiden and hyperhomocysteinemia in a thrombotic family.

We report a thrombotic family with combined type I antithrombin deficiency and factor V Leiden (factor V-R506Q) in which the proposita, affected by recurrent venous and arterial thrombosis, was also characterized by mild hyperhomocysteinemia (28 micromol/l; normal <18.5 micromol/l). Her two thrombotic sisters, with normal antithrombin levels and factor V molecules, showed hyperhomocysteinemia (51 and 30 micromol/l, respectively). Four other members of the family had the combined antithrombin/factor V Leiden defect and two of them had thrombosis. The common A223V mutation in the methylenetetrahydrofolate reductase gene, responsible for the thermolabile variant of the enzyme, was found to be heterozygous in the proposita; the two sisters were homozygous and heterozygous, respectively. The heterozygous sister also had a high titre of antiphospholipid antibodies (85 units of immunoglobulin G antiphospholipid antibody/ml). Furthermore, low plasma folate levels were found in the three hyperhomocysteinemic subjects of the family. This family with several prothrombotic defects is a clear example of the polyfactorial nature of thrombophilia.

Resistance to activated protein C and low levels of protein S activity in nine thrombophilic families: a correct diagnosis.

In order to define the thrombophilic conditions related to activated protein C resistance (APC-R) and protein S (PS) deficiency and to detect the possible combination of these defects, we studied nine unrelated patients selected because of low anticoagulant response to APC and reduced PS activity with at least one first degree relative having the same coagulation feature. The mean APC ratio was 0.64 (normal values > 0.80) and range 0.35-0.80. Three of the patients were heterozygous and two were homozygous for the Leiden mutation (FVR506Q); in the remaining four there was no mutation. The mean PS activity was 41.6% and range 32-54 (normal 65-150%). Five of the patients had low PS activity despite normal total and free antigenic levels, and normal activity when measured at higher plasma dilution; these were carrying at least one gene for the Leiden mutation. In the remaining four patients the crossed-immunoelectrophoresis and the Western-blotting analysis showed a type I PS deficiency confirmed by the familial restriction fragment length polymorphism analysis. Thus, four families were diagnosed with the type I PS defect and five with congenital APC-R. No combined PS/FV Leiden or type II PS defect was found. The only defect found was in the anticoagulant PC pathway. We therefore designed a procedure to diagnose thrombophilic conditions related to this pathway. This study indicates that a specific methodological approach must be used to accurately characterize APC-R and PS deficiency and that care is necessary to avoid the possibility of misdiagnosis.

Thrombosis of mechanical heart valve prostheses: revisiting the role of fluoroscopy.

Prosthetic valve thrombosis is a rare but potentially fatal complication of heart valve replacement. Symptoms may be misleading, yet the condition may rapidly lead to death. A prompt diagnosis is therefore crucial. Ultrasound is the most often used technique for evaluating prosthesis dysfunction. We describe two cases of prosthesis thrombosis with negative Doppler results but with distinctly abnormal leaflet motion at fluoroscopy. A correct diagnosis would have been missed if the Doppler evaluation alone was relied on. Fluoroscopy should always form part of the diagnostic work-up in patients with artificial heart valves.

Fluid-structure interaction within realistic three-dimensional models of the aneurysmatic aorta as a guidance to assess the risk of rupture of the aneurysm.

Abdominal aortic aneurysm (AAA) disease is a degenerating process whose ultimate event is the rupture of the vessel wall. Rupture occurs when the stresses acting on the wall rise above the strength of the AAA wall tissue. The complex mechanical interaction between blood flow and wall dynamics in a three dimensional custom model of a patient AAA was studied by means of computational coupled fluid-structure interaction analysis. Real 3D AAA geometry is obtained from CT scans image processing. The results provide a quantitative local evaluation of the stresses due to local structural and fluid dynamic conditions. The method accounts for the complex geometry of the aneurysm, the presence of a thrombus and the interaction between solid and fluid. A proven clinical efficacy may promote the method as a tool to determine factual aneurysm risk of rupture and aid the surgeon to refer elective surgery patients.

[Etiopathogenetic considerations on so-called moderate thrombopenia in young women]. / Considerazioni etio-patogenetiche sulla cosiddetta piastrinopenia modica delle giovani donne.

Twenty cases of moderate thrombocytopenia in young women were examined in an assessment of the nosological status of this form. Parameters enjoying pathogenetic significance were distinguished in some instances: 4 cases displayed dysendocrinopathy, 2 the signs of consumption coagulopathy, 3 an antibody situation attributable to compensated autoimmune thrombocytopenia, and 3 a probable central inhibition of thrombocytopoiesis due to drugs. Since no significant cause could be determined in the remaining 8 cases, it can be said that this syndrome occupies a special place among the forms of chronic thrombocytopenia.

[Platelet hyperfunction in prethrombotic vascular disease]. / L'iperattività piastrinica in patologia vascolare pretrombotica.

In 3 groups of patients with high thrombotic risk (diabetes mellitus, hyperbetalipoproteinemia, hypertension) the platelet aggregation and the level of circulating platelet aggregates were found statistically higher than in normal controls. In addition, platelet aggregation in diabetic patients was found statistically higher than in the other 2 groups of patients. Therefore these 2 parameters of platelet function are useful for the screening of patients with potential risk for thrombosis allowing a more selective and defined prophylaxis, both of thrombosis and atherosclerotic complications.

Giant anastomotic pseudoaneurysm after Bentall operation causing late postoperative cardiogenic shock.

Pseudoaneurysm of the ascending aorta is a rare but severe complication occurring after composite graft surgery for combined aortic valve and ascending aorta disease. The diagnosis of this condition can be difficult because anastomotic pseudoaneurysms show highly variable clinical features depending on the site of the aortic dehiscence and on the involvement of the surrounding structures. We report an unusual case of a late postoperative aortic graft dehiscence, causing acute right heart failure.