The Production of Platelet-Activating Factor during Hemodialysis

Regenerated cellulosic membranes (CU) induced the aggregation of plasma-free human neutrophils when recirculated in a dynamic model of dialysis without the patient on the circuit. Neutrophil aggregation was linked to the production of PAF by these cells. In the absence of detectable PAF production, no neutrophil aggregation occurred, as observed during recirculation with polymethylmethacrylate (PMMA) membranes. With polycarbonate (PC), PAF production and aggregation of neutrophils were both almost half the values with CU. PAF production was studied in ten hemodialysis (HD) patients tested twice with CU and once with PC and PMMA membranes. PAF was extracted in the venous blood during filling of the dialyser for 9/20 of patients with CU (3.1 ± 2.9 ng/ml, mean ± 1 S.D.) a membrane that induced marked leukopenia (> 50% of basal values at 15 min), C3a des Arg generation (> 500% at 5 min), and plasma levels of the elastase-alpha1-proteinase inhibitor complex (> 500% at the end of HD). Membranes such as PC and PMMA showing intermediate or low potential to induce leukopenia and C3a des Arg generation, respectively, did not trigger the production and release of PAF in detectable amounts at any interval. However, with PMMA, plasma neutrophil elastase was significantly higher than baseline at the end of dialysis. These levels were not significantly different (p < 0.05) from those observed with CU and PC membranes

IL-6, but not IFN-gamma, triggers apoptosis and inhibits in vivo growth of human malignant T cells on STAT3 silencing

STAT1 and STAT3 are the main mediators of the signaling of interferons (IFNs) and of gp130 cytokines, respectively. Neoplastic T lymphocytes frequently become resistant to the IFN-gamma/STAT1 apoptotic pathway, often because of the downregulation of the IFN-gammaR2 receptor chain. Many studies suggest that cross-regulation between different STATs, in particular between STAT1 and STAT3, may profoundly affect cytokine/growth factor signaling. Here, the function of STAT3 in the negative regulation of STAT1 apoptotic pathway was investigated by RNA interference-mediated STAT3 silencing in human malignant T lymphocytes. In STAT3-depleted cells, interleukin (IL)-6 acquired the capacity to induce apoptosis, correlating with prolonged STAT1 activation and the induction of major histocompatibility complex (MHC) class I expression. In contrast, in the absence of STAT3, IFN-gamma could slightly enhance apoptosis but its ability to induce MHC class I expression was unchanged. Accordingly, IL-6, but not IFN-gamma, could significantly impair the in vivo growth of STAT3-depleted human neoplastic T lymphocytes transplanted into severe combined immunodeficient mice. Therefore, treatment with IL-6 and simultaneous STAT3 silencing may represent a potential therapeutic approach to control the expansion of IFN-gamma-unresponsive neoplastic T cells.

Musculoskeletal tumours: preliminary experience with perfusion MRI

PURPOSE

Our study aimed to assess the role of magnetic resonance imaging (MRI) in the characterisation of musculoskeletal tumours and to identify specific perfusion patterns for the different tumours.

MATERIALS AND METHODS

Between January 2003 and September 2005, we evaluated the conventional and perfusion MRIs of 39 patients with musculoskeletal tumours. Dynamic MRI was performed with a 1.5-T and 1.0-T MRI unit before and after the intravenous administration of contrast material, using dedicated phased-array coils appropriate for the region to be studied and fast and ultrafast consecutive sequences. Postprocessing was done on an independent workstation (Advantage Windows, GE Medical System), with Functool (GE) software, which allowed a quantitative evaluation of enhancement as a function of time. The results were compared with the histopathological diagnoses obtained by biopsy or surgery.

RESULTS

The lesions identified in the 39 patients included 23 soft tissue tumours (12 benign, 11 malignant) and 16 bone tumours (ten benign, six malignant). Comparing the time-intensity diagrams of lesions of the same histological type, we found typical enhancement patterns for some bone tumours only, especially for bone, cartilaginous, fibrohistiocytic and pseudoinflammatory lesions. No typical enhancement pattern could be detected for any of the histological types of soft tissue tumour. Analysis of the slope of the time-intensity curves has a sensitivity and specificity of 64%-58% for soft tissue tumours and 86%-67% for bone tumours in determining the biological aggressiveness of the lesions.

CONCLUSIONS

Perfusion MRI had moderate sensitivity and specificity in the differential diagnosis between lesions with high or low biological activity. Only in a few cases was it possible to find some correlation between perfusion patterns and lesion histology. The slope values should therefore be used in combination with conventional spin-echo images and other imaging and clinical data in order to narrow the field of the possible differential diagnoses and reliably predict the nature of the lesion.

The integration of vascular surgical techniques with oncological surgical protocols in the treatment of soft tissue sarcomas of the limbs

Soft tissue tumors, involving the vascular bundle, require a particular surgical approach: oncological and vascular surgical techniques must be integrated in order to perform a limb-saving surgery with adequate margins. Thirty-six soft tissue sarcomas of the thigh and popliteal region were treated from June 1999 to September 2002. Nineteen cases involving the vascular bundle were analysed and placed in two groups according to imaging and clinical information: Group A, 14 patients, with tumors close to femoral vessels without adventitial infiltration, and Group B, 5 patients, with vascular infiltration. Group A was treated with vascular blunt dissection performing adventitial excision. Group B was treated with vascular "en-bloc" resection and reconstruction. Imaging and clinical information together with surgical techniques, strategies and complications were analysed in order to plan the surgical approach in neoplastic vascular bundle involvement.

Fibro-cartilaginous lesions of the glenoid labrum in shoulder instability: a proposed classification using sagittal-oblique arthro-MRI

PURPOSE

To propose a graded classification of lesions of the fibrocartilaginous glenoid labrum in traumatic dislocations of the shoulder, based on arthro-MRI in sagittal-oblique views.

MATERIALS AND METHODS

Seventy-one patients with histories of chronic post-traumatic shoulder instability were studied from May 2000 to May 2001. MR images were obtained using superconducting magnets operating at 1 and 1.5 Tesla, with a dedicated shoulder coil. The study was carried out in combination with arthrography, with axial sections oriented perpendicularly to the longitudinal axis of the glena, oblique coronal sections parallel to the course of the supraspinous muscle tendon and oblique sagittal sections with axis parallel to the longitudinal axis of the glena.

RESULTS

In one case an anatomical variant was found (Buford complex). In 18 patients a simple fissuration of the fibrocartilaginous glenoid labrum was found, whereas 28 patients displayed more extensive lesions affecting the middle-inferior portions of the labrum. In 15 patients the lesion extended to the middle-superior third of the glena, involving the middle glenohumeral ligament. In 9 cases, in addition to a complete lesion of the labrum, with typical "bucket-handle" appearance, a lesion of the superior and middle glenohumeral ligaments was also observed.

DISCUSSION AND CONCLUSIONS

In traumatic shoulder dislocations it is essential to provide the surgeon with precise information regarding the location, extension and degree of damage to the capsule, ligaments and especially the labrum of the glenohumeral joint. On the basis of the results obtained in the sagittal-oblique sections we propose an MR-arthrography classification dividing lesions of the fibrocartilaginous labrum into 4 grades.

[Magnetic resonance arthrography. Preliminary experience in study technic and main diagnostic applications]

In the study of osteoarticular conditions, MRI makes a definite diagnostic improvement, even though some problems are still to be solved. Thus, on the basis of their arthrographic experience, the authors experimentally applied this technique to MRI, to assess the actual feasibility of MR arthrography. Forty-three patients were selected to undergo MR examinations after the intraarticular injection of 15-20 ml paramagnetic contrast agent (Gd-DTPA), with 0.25% saline solution. Before MR arthrography every patient underwent a baseline MR arthrography exam. Normal anatomy was better depicted with MR arthrography. In all cases, even small lesions and other structural changes missed at baseline MRI were demonstrated. Therefore, in agreement with previous arthrographic and CT arthrographic reports, we believe MR arthrography to be a simple technique improving MR diagnostic capabilities in selected cases.

The production of platelet-activating factor during hemodialysis

Regenerated cellulosic membranes (CU) induced the aggregation of plasma-free human neutrophils when recirculated in a dynamic model of dialysis without the patient on the circuit. Neutrophil aggregation was linked to the production of PAF by these cells. In the absence of detectable PAF production, no neutrophil aggregation occurred, as observed during recirculation with polymethylmethacrylate (PMMA) membranes. With polycarbonate (PC), PAF production and aggregation of neutrophils were both almost half the values with CU. PAF production was studied in ten hemodialysis (HD) patients tested twice with CU and once with PC and PMMA membranes. PAF was extracted in the venous blood during filling of the dialyser for 9/20 of patients with CU (3.1 +/- 2.9 ng/ml, mean +/- 1 S.D.) a membrane that induced marked leukopenia (greater than 50% of basal values at 15 min), C3a des Arg generation (greater than 500% at 5 min), and plasma levels of the elastase-alpha 1-proteinase inhibitor complex (greater than 500% at the end of HD). Membranes such as PC and PMMA showing intermediate or low potential to induce leukopenia and C3a des Arg generation, respectively, did not trigger the production and release of PAF in detectable amounts at any interval. However, with PMMA, plasma neutrophil elastase was significantly higher than baseline at the end of dialysis. These levels were not significantly different (p less than 0.05) from those observed with CU and PC membranes.

Kinetic analysis of the response of plasma glucose, insulin, and C-peptide to glucagon injection in normal and diabetic subjects

A compartmental model formed by plasma glucose, proinsulin, insulin, and C-peptide was proposed to allow a quantitative evaluation of the interrelationship among the different components of the system and to obtain a better discrimination between normal and pathologic subjects. In 11 control subjects, in 6 mild diabetics, and in 9 severe diabetics (insulin-dependent), the kinetics of plasma glucose, insulin, and C-peptide after an i.v. injection of glucagon (sampling for about 120 min) were fitted to the model which was solved with digital computing techniques. Since biphasic plasma insulin and C-peptide kinetics were demonstrated in many normals and mild diabetics, the effect of glucagon in the model was represented by a differential plus a proportional effect. The model (formed by 6 compartments and 14 transfer constants) takes into account the fact that insulin and C-peptide derive monomolecularly from proinsulin and that liver inactivates insulin. The values of the parameters obtained were submitted to stepwise discriminant analysis in order to obtain their relative importance in discriminating among the three groups of subjects. With respect to normal subjects, we found in diabetics an increased inflow of glucose into plasma; a decreased effect of glucagon in promoting the proinsulin response; a decreased effect of glucose in promoting the proinsulin response; a decreased glucose utilization; a lower coupling effect of insulin on glucose; and a higher disappearance rate of C-peptide. We observed a lower formation of insulin and C-peptide from proinsulin in severe diabetics.

[Determination of plasmatic C-peptide and its clinical uses]

Physiopathological basis and methodological implications of the radioimmunological estimation of plasma C-peptide, as a test of beta cell secretory activity, are reviewed. Personal results are reported concerning C-peptide assay, both in basal and stimulative conditions, in insulindependent long-and short-term diabetes. In 1 case of organic, and 2 cases of functional hyperinsulinism, the test gave useful clinical information. The method of L. Heding-Novo Research Institute, Bagsvaerd, Denmark-, with previous elimination of proinsulin and insulinantibody in patients with high values of IgG insulin binding, proved to be suitable to endocrinological routine.

[Treatment with monocomponent semi-lente insulin in diabetes of difficult compensation]

According to personal experience, good clinical effects may be obtained by monocomponent insulin treatment, independently from strict immunological indications (i.e. high plasma-anti-insulin antibody titers). The present paper reports on a two daily injection treatment with monocomponent Semilente insulin (SeLe MC) in comparison with an earlier management with conventional retard insulins, in a group of 16 insulin dependent diabetics, selected among the most poorly controlled patients with unstable diabetes and/or high insulin requirement. In 6 subjects, after transfer to SeLe MC, it was observed a reduction in M bs, delta, and M delta indices of the glycemic regulation, indicating lower mean glycemic profiles with fewer irregularities. In 11 cases a marked improvement in the subjective symptomatology was noticed. Some minor hypoglycemic reactions induced to a reduction in the high insulin requirement in 8 cases. All but two patients had significant values of insulin IgG antibodies. The period of observation was too short to take in consideration an immunological modification, as an explanation of the present clinical results. However, these could be hypothetically referred to an amelioration in the releasing of endogenous insulin and/or in the hormone-receptor interaction as a consequence of treatment with monocomponent insulin preparations, in comparison to non purified conventional preparations. Treatment with SeLe MC seems to be suitable in particularly difficult control of the diabetes and in emergency situations.

Proinsulin and A-component antibodies in diabetics after long-term monocomponent insulin treatment

In newly diagnosed diabetics treated with Monotard (porcine monocomponent (MC) Lente insulin) for five years, no antibodies against porcine or bovine proinsulin were observed, but 2 of 13 subjects developed a-component antibodies. In newly diagnosed diabetics, treatment for the same period with conventional Lente insulin induced both proinsulin and a-component antibodies (in 5 and 8 of 10 cases, respectively). In 31 patients transferred from conventional Lente to Monotard, proinsulin and a-component antibody levels were significantly lower than in 22 patients maintained on conventional Lente after the 5-year follow-up period. No significant differences were noted between bovine and procine proinsulin antibodies. Insulin antibody production was similar to that of proinsulin antibody.