Vortex polarization and circulation statistics in isotropic turbulence

We carry out an in-depth analysis of a recently introduced vortex gas model of homogeneous and isotropic turbulence. Direct numerical simulations are used to provide a concrete physical interpretation of one of the model's constituent fields: the degree of vortex polarization. Our investigations shed light on the complexity underlying vortex interactions and reveal, furthermore, that despite some striking similarities, classical and quantum turbulence exhibit distinct structural characteristics, even at inertial range scales. Crucially, these differences arise due to correlations between the polarization and circulation intensity within vortex clusters.

Statistics of extreme turbulent circulation events from multifractality breaking

Recent numerical explorations of extremely intense circulation fluctuations at high Reynolds number flows have brought to light novel aspects of turbulent intermittency. Vortex gas modeling ideas, which are related to a picture of turbulence as a dilute system of vortex tube structures, have been introduced alongside such developments, leading to accurate descriptions of the core and the intermediate tails of circulation probability distribution functions (cPDFs), as well as the scaling exponents associated to statistical moments of circulation. We extend the predictive reach of the vortex gas picture of turbulence by emphasizing that multifractality breaking, one of its salient phenomenological ingredients, is the key concept to disclose the asymptotic form of cPDF tails. A remarkable analytical agreement is found with previous results derived within the framework of the instanton approach to circulation intermittency, a functional formalism devised to single out the statistically dominant velocity configurations associated to extreme circulation events.

Circulation statistics and the mutually excluding behavior of turbulent vortex structures

The small-scale statistical properties of velocity circulation in classical homogeneous and isotropic turbulent flows are assessed through a modeling framework that brings together the multiplicative cascade and the structural descriptions of turbulence. We find that vortex structures exhibit short-distance repulsive correlations, which is evidenced when they are "tomographically" investigated, by means of planar cuts of the flow, as two-dimensional vortex gases. This phenomenon is suggested from model improvements which allow us to obtain an accurate multiscale description of the intermittent fluctuations of circulation. Its crucial new ingredient, the conjectured hard disk behavior of the effective planar vortices, is then found to be strongly supported from a study of their spatial distributions in direct numerical simulations of the Navier-Stokes equations.

Multifractality breaking from bounded random measures

Multifractal systems usually have singularity spectra defined on bounded sets of Hölder exponents. As a consequence, their associated multifractal scaling exponents are expected to depend linearly on statistical moment orders at high-enough orders-a phenomenon referred to as the linearization effect. Motivated by general ideas taken from models of turbulent intermittency and focusing on the case of two-dimensional systems, we investigate the issue within the framework of Gaussian multiplicative chaos. As verified by means of Monte Carlo simulations, it turns out that the linearization effect can be accounted for by Liouville-like random measures defined in terms of upper-bounded scalar fields. The coarse-grained statistical properties of Gaussian multiplicative chaos are furthermore found to be preserved in the linear regime of the scaling exponents. As a related application, we look at the problem of turbulent circulation statistics, and obtain a remarkably accurate evaluation of circulation statistical moments, recently determined with the help of massive numerical simulations.

Vortex gas modeling of turbulent circulation statistics

Statistical properties of circulation encode relevant information about the multiscale structure of turbulent cascades. Recent massive computational efforts have posed challenging theoretical issues, such as the dependence of circulation moments upon Reynolds numbers and length scales, and the specific shape of the heavy-tailed circulation probability distribution functions. We address these focal points in an investigation of circulation statistics for planar cuts of three-dimensional flows. The model introduced here borrows ideas from the structural approach to turbulence, whereby turbulent flows are depicted as dilute vortex gases, combined with the standard Obukhov-Kolmogorov phenomenological framework of small-scale intermittency. We are able to reproduce, in this way, key statistical features of circulation, in close agreement with empirical observations compiled from direct numerical simulations.

Magnetic dissipation of near-wall turbulent coherent structures in magnetohydrodynamic pipe flows

Relaminarization of wall-bounded turbulent flows by means of external static magnetic fields is a long-known phenomenon in the physics of electrically conducting fluids at low magnetic Reynolds numbers. Despite the large literature on the subject, it is not yet completely clear what combination of the Hartmann (M) and the Reynolds number has to be used to predict the laminar-turbulent transition in channel or pipe flows fed by upstream turbulent flows free of magnetic perturbations. Relying upon standard phenomenological approaches related to mixing length and structural concepts, we put forward that M/R_{τ}, where R_{τ} is the friction Reynolds number, is the appropriate controlling parameter for relaminarization, a proposal which finds good support from available experimental data.

Toy model for vortex-ring-assisted particle drag in superfluid counterflow

The interpretation of data obtained from particle image and tracking velocimetry in the study of superfluid flows has been so far a challenging task. Tracking particles (as solid hydrogen or deuterium) are attracted to the cores of quantized vortices, so that their dynamics can be strongly affected by the surrounding vortex tangle. Previous phenomenological arguments indicate that tracking particles and microsized vortex rings could form bound states (denoted here as VRP states). While a comprehensive description of the vortex ring-particle bonding mechanism has to deal with somewhat involved flow configurations, we introduce a simplified two-dimensional model of VRP states, which captures essential qualitative features of their three-dimensional counterparts. Besides an account of known experimental and numerical observations, the model proves to be of great heuristic interest. In particular, it sheds light on the important role played by viscous dissipation (due to the normal component of the fluid), the Magnus force, and topologically excited vortex rings in the stability and dynamics of VRP states.

Onset of intermittency in stochastic Burgers hydrodynamics

We study the onset of intermittency in stochastic Burgers hydrodynamics, as characterized by the statistical behavior of negative velocity gradient fluctuations. The analysis is based on the response functional formalism, where specific velocity configurations-the viscous instantons-are assumed to play a dominant role in modeling the left tails of velocity gradient probability distribution functions. We find, as expected on general grounds, that the field-theoretical approach becomes meaningful in practice only if the effects of fluctuations around instantons are taken into account. Working with a systematic cumulant expansion, it turns out that the integration of fluctuations yields, in leading perturbative order, to an effective description of the Burgers stochastic dynamics given by the renormalization of its associated heat kernel propagator and the external force-force correlation function.

Trend of decreasing length of cervical cone excision during the last 20 years

OBJECTIVE

The aim of the present investigation was to evaluate the cervical conizations performed in the last 20 years in a single institution, with a particular interest in analyzing the trend of the length of cone excisions.

PATIENTS AND METHODS

A retrospective cohort study of women who underwent a CO2-laser cervical conization between January 1996 and December 2015. Cytological abnormalities on referral pap smear, colposcopic findings and pertinent clinical and socio-demographic characteristics of each woman were collected. In particular, the length of cone specimen was evaluated, taking into account all the factors potentially influencing the length of excision.

RESULTS

A total of 1270 women who underwent cervical conization from January 1996 to December 2015 were included in the analysis. A mean cone length of 15.1 ± 5.7 mm was reported, and we observed a significant decrease in the length of cone excisions over the whole study period. Age (rpartial = 0.1543, p < 0.0001), see & treat procedure (rpartial = -0.1945, p < 0.0001) and grade II colposcopic findings (rpartial = 0.1540, p < 0.0001) were significantly associated with the length of cone excision on multivariate analysis.

CONCLUSIONS

In the last 20 years, a significant decrease in the length of cone excision was observed. In our opinion, this can be due to the acquired awareness by the gynecologists of the potential disadvantages of wide cone excision in term of adverse obstetric outcomes in future pregnancies.

Predictors of malignancy in endometrial polyps: a multi-institutional cohort study

PURPOSE OF INVESTIGATION

The risk of endometrial cancer in women with endometrial polyps (EPs) has been reported to vary between 0.3% and 4.8%. There is a lack of data about the management of asymptomatic women with incidental diagnosis of EPs. In the present study the authors correlated demographic and clinical characteristics with histopathological features of the EPs hysteroscopically removed.

MATERIALS AND METHODS

An observational multi-institutional cohort study was conducted from February 2010 to December 2012 to identify all the premenopausal and postmenopausal women consecutively undergoing hysteroscopic polypectomy. The data of women were reviewed and clinical features were related to histopathologic results.

RESULTS

The patients recruited were 813. The mean age was 52.5 years (range 22-87). The results showed a correlation between older age, high body mass index (BMI) and obesity, postmenopausal state, abnormal uterine bleeding (AUB), hypertension, and risk of malignant EPs. On multivariable analysis, the correlation remained only for age (OR 1.08, 95% CI 1.03 - 1.14) and AUB (OR 3.53, 95% CI 1.87 - 6.65).

CONCLUSION

Older patients in postmenopausal status with AUB, a high BMI, and hypertension are at higher risk for premalignant and malignant polyps. In these patients a surgical approach should be used, consisting in hysteroscopical removing of the polyp.

Vorticity statistics and the time scales of turbulent strain

Time scales of turbulent strain activity, denoted as the strain persistence times of first and second order, are obtained from time-dependent expectation values and correlation functions of Lagrangian rate-of-strain eigenvalues taken in particularly defined statistical ensembles. Taking into account direct numerical simulation data, our approach relies on heuristic closure hypotheses which allow us to establish a connection between the statistics of vorticity and strain. It turns out that softly divergent prefactors correct the usual "1/s" strain time-scale estimate of standard turbulence phenomenology, in a way which is consistent with the phenomenon of vorticity intermittency.

Gastric syphilis: a case-report

CLINICAL CASE A 43-year-old Romanian woman was referred with the clinical suspicion of gastric lymphoma; she had complained from two months nausea, vomiting and weight loss (7 kg); 3 esophagogastroduodenoscopic examinations had evidenced reduced distensibility of stomach body and antrum, ulcered and congestive mucosa, the histopathological examinations revealed a non specific inflammation. There was no response to therapy with omeprazolo. A computer-assisted tomoghraphy scan of the thorax and abdomen, obtained after the oral and intravenous administration of contrast material, showed diffuse thickening of the gastric wall, lymphadenopathies were seen in the retrocrural space, lesser curvature, and paraaortic region. It was performed another upper endoscopy with “deep” biopsy specimen, comprehensive of spirochetal immunohistochemistry, that was diagnostic for gastric syphilis. DISCUSSION Even though gastritis is a rare clinical manifestations of the secondary stage of syphilis, it must be considered in the differential diagnosis of erosive gastritis unresponsive to medical therapy, especially in young patients; screening tests like VDRL (routinely used until few years ago in internal medicine divisions) may be useful to identify those patients needing a further diagnostic evaluation.

Markov chain modeling of polymer translocation through pores

We solve the Chapman-Kolmogorov equation and study the exact splitting probabilities of the general stochastic process which describes polymer translocation through membrane pores within the broad class of Markov chains. Transition probabilities, which satisfy a specific balance constraint, provide a refinement of the Chuang-Kantor-Kardar relaxation picture of translocation, allowing us to investigate finite size effects in the evaluation of dynamical scaling exponents. We find that (i) previous Langevin simulation results can be recovered only if corrections to the polymer mobility exponent are taken into account and (ii) the dynamical scaling exponents have a slow approach to their predicted asymptotic values as the polymer's length increases. We also address, along with strong support from additional numerical simulations, a critical discussion which points in a clear way the viability of the Markov chain approach put forward in this work.

Conformal invariance in (2+1)-dimensional stochastic systems

Stochastic partial differential equations can be used to model second-order thermodynamical phase transitions, as well as a number of critical out-of-equilibrium phenomena. In (2+1) dimensions, many of these systems are conjectured (and some are indeed proved) to be described by conformal field theories. We advance, in the framework of the Martin-Siggia-Rose field-theoretical formalism of stochastic dynamics, a general solution of the translation Ward identities, which yields a putative conformal energy-momentum tensor. Even though the computation of energy-momentum correlators is obstructed, in principle, by dimensional reduction issues, these are bypassed by the addition of replicated fields to the original (2+1)-dimensional model. The method is illustrated with an application to the Kardar-Parisi-Zhang (KPZ) model of surface growth. The consistency of the approach is checked by means of a straightforward perturbative analysis of the KPZ ultraviolet region, leading, as expected, to its c=1 conformal fixed point.

Log-Poisson cascade description of turbulent velocity-gradient statistics

The Log-Poisson phenomenological description of the turbulent energy cascade is evoked to discuss high-order statistics of velocity derivatives and the mapping between their probability distribution functions at different Reynolds numbers. The striking confirmation of theoretical predictions suggests that numerical solutions of the flow obtained at low/moderate Reynolds numbers can play an important quantitative role in the analysis of experimental high Reynolds number phenomena, where small scales fluctuations are in general inaccessible from direct numerical simulations.

Instanton theory of Burgers shocks and intermittency

A Lagrangian approach to Burgers turbulence is carried out along the lines of the field theoretical Martin-Siggia-Rose formalism of stochastic hydrodynamics. We derive, from an analysis based on the hypothesis of unbroken Galilean invariance, the asymptotic form of the probability distribution function of negative velocity differences. The origin of Burgers intermittency is found to rely on the dynamical coupling between shocks, identified to instantons, and noncoherent background fluctuations, which-then-cannot be discarded in a consistent statistical description of the flow.

Minimalist turbulent boundary layer model

We discuss an elementary model of a turbulent boundary layer over a flat surface given as a vertical random distribution of spanwise Lamb-Oseen vortex configurations placed over a nonslip boundary-condition line. We are able to reproduce several important features of realistic flows, such as the viscous and logarithmic boundary sublayers, and the general behavior of the first statistical moments (turbulent intensity, skewness, and flatness) of the streamwise velocity fluctuations. As an application, we advance some heuristic considerations on the boundary layer underlying kinematics that could be associated with the phenomenon of drag reduction by polymers, finding a suggestive support from its experimental signatures.

Large-scale intermittency in the atmospheric boundary layer

We find actual evidence, relying upon vorticity time series taken in a high-Reynolds-number atmospheric experiment, that to a very good approximation the surface boundary layer flow may be described, in a statistical sense and under certain regimes, as an advected ensemble of homogeneous turbulent systems, characterized by a log-normal distribution of fluctuating intensities. Our analysis suggests that the usual direct numerical simulations of homogeneous and isotropic turbulence, performed at moderate Reynolds numbers, may play an important role in the study of turbulent boundary layer flows, if supplemented with appropriate statistical information concerned with the structure of large-scale fluctuations.

[Census 2004 of the Italian Renal and Dialysis Units. Emilia-Romagna, Toscana]

The 2004 SIN census of the Italian nephrology and dialysis centres showed many interesting data about the epidemiology and the organization in the Regions of Emilia-Romagna (ER) and Tuscany (T). A) Epidemiology: incidence of dialysis patients 169 pmp (patients per million population) in ER, 147 ppm in T; prevalence of dialysis patients 639 pmp and 665 pmp, respectively; prevalence of transplanted patients 325 ppm in ER and 233 pmp in T; gross mortality of dialysis patients 16.3% and 13.4%, respectively; B) Type of vascular access in prevalently dialysis patients: arteriovenous fistula 83% and 78%; central venous catheter 13% and 12%; vascular graft 5% and 9%. C) Structural resources: nephrology beds 44 mp (per million population) and 50 mp; dialysis places 157 and 146 mp. D) Personnel resources : renal physicians 29 and 41 mp; renal nurses 171 and 202 mp ; each renal physician cares for 22 and 16 dialysis patients, and each renal nurse takes care of 3.7 and 3.3 dialysis patients. E) Activity: hospital admissions 1572, 1769 pmp; renal biopsies 115 and 166 pmp.

[Update of the Italian Society of Nephrology Project No. 1 of the 2004-2006 SIN programme]

In the last few years the Italian Society of Nephrology has addressed many technical-scientific and management aspects to better patient satisfaction. Project No. 1 of the 2004-2006 programme on 'Quality and Accreditation of National Renal Units' focuses on four essential points. The first is the questionnaire mailed to all the Presidents and Regional Delegates on the relationship between Nephrology units, Local Government Health-System and the Regional Healthcare Agency. The results evidence that the 'political' decision-making power of nephrologists decreases in the absence of a national strategy. The second point, in collaboration with the National Census Group, includes the quality analysis and the standardization of resources (human and structural) and management of the Renal Units. The third point is based on 'Educational Courses for Quality and Accreditation' held in Rome (3-5 October 2005: L'Accreditamento all'Eccellenza dell'Unita' Operativa di Nefrologia, Dialisi e Trapianto; 17-19 October 2005: Il Manuale di Accreditamento della Specialità di Nefrologia). The courses aim at training members responsible for each region to hold courses in their specific region to create a network including each single Renal Unit to create an acceptable homogenous language on the models of analysis and on the correct use of 'The Guide for Excellence Accreditation'. The fourth point concerns both the on-line Guide for Excellence Accreditation and 'Peer Review Accreditation' and the NEQUASY (Nephrology Quality System) project. The manual must be 'user friendly' allowing each Centre to self-evaluate using national and regional standards.

Langevin simulation of the chirally decomposed sine-Gordon model

A large class of quantum and statistical field theoretical models, encompassing relevant condensed matter and non-Abelian gauge systems, are defined in terms of complex actions. As the ordinary Monte Carlo methods are useless in dealing with these models, alternative computational strategies have been proposed along the years. The Langevin technique, in particular, is known to be frequently plagued with difficulties such as strong numerical instabilities or subtle ergodic behavior. Regarding the chirally decomposed version of the sine-Gordon model as a prototypical case for the failure of the Langevin approach, we devise a truncation prescription in the stochastic differential equations which yields numerical stability and is assumed not to spoil the Berezinskii-Kosterlitz-Thouless transition. This conjecture is supported by a finite size scaling analysis, whereby a massive phase ending at a line of critical points is clearly observed for the truncated stochastic model.

Stochastic perturbations in vortex-tube dynamics

A dual lattice vortex formulation of homogeneous turbulence is developed, within the Martin-Siggia-Rose field theoretical approach. It consists of a generalization of the usual dipole version of the Navier-Stokes equations, known to hold in the limit of vanishing external forcing. We investigate, as a straightforward application of our formalism, the dynamics of closed vortex tubes, randomly stirred at large length scales by Gaussian stochastic forces. We find that besides the usual self-induced propagation, the vortex tube evolution may be effectively modeled through the introduction of an additional white-noise correlated velocity field background. The resulting phenomenological picture is closely related to observations previously reported from a wavelet decomposition analysis of turbulent flow configurations.

Statistics of intense turbulent vorticity events

We investigate statistical properties of vorticity fluctuations in fully developed turbulence, which are known to exhibit a strong intermittent behavior. Taking as the starting point the Navier-Stokes equations with a random force term correlated at large scales, we obtain in the high Reynolds number regime a closed analytical expression for the probability distribution function of an arbitrary component of the vorticity field. The central idea underlying the analysis consists in the restriction of the velocity configurational phase-space to a particular sector where the rate of strain and the rotation tensors can be locally regarded as slow and fast degrees of freedom, respectively. This prescription is implemented along the Martin-Siggia-Rose functional framework, whereby instantons and perturbations around them are taken into account within a steepest-descent approach.

Extended self-similarity in the two-dimensional metal-insulator transition

We show that extended self-similarity, a scaling phenomenon first observed in classical turbulent flows, holds for a two-dimensional metal-insulator transition that belongs to the universality class of random Dirac fermions. Deviations from multifractality, which in turbulence are due to the dominance of diffusive processes at small scales, appear in the condensed-matter context as a large-scale, finite-size effect related to the imposition of an infrared cutoff in the field theory formulation. We propose a phenomenological interpretation of extended self-similarity in the metal-insulator transition within the framework of the random beta-model description of multifractal sets. As a natural step, our discussion is bridged to the analysis of strange attractors, where crossovers between multifractal and nonmultifractal regimes are found and extended self-similarity turns out to be verified as well.

Circulation-strain sum rule in stochastic magnetohydrodynamics

We study probability density functions (PDFs) of the circulation of velocity and magnetic fields in magnetohydrodynamics, computed for a circular contour within inertial range scales. The analysis is based on the instanton method as adapted to the Martin-Siggia-Rose field theory formalism. While in the viscous limit the expected Gaussian behavior of fluctuations is indeed verified, the case of vanishing viscosity is not suitable of a direct saddle-point treatment. To study the latter limit, we take into account fluctuations around quasistatic background fields, which allows us to derive a sum rule relating PDFs of the circulation observables and the rate of the strain tensor. A simple inspection of the sum rule definition leads straightforwardly to the algebraic decay rho(Gamma)-1/Gamma(2) at the circulation PDF tails.

Proteinuria in focal segmental glomerulosclerosis: role of circulating factors and therapeutic approach

The clinical course of primary Focal Segmental Glomerulosclerosis (FSGS) is frequently complicated by nephrotic range proteinuria and progression to renal failure. The high recurrence rate of the disease in transplanted kidney suggests the hypothesis that such patients have a circulating factor that alters glomerular capillary permeability. In recent years some authors found that serum from patients with FSGS increases glomerular permeability to albumin and partially identified the permeability factor (PF) as a protein of 30-50 Kd m.w. The removal of this protein by means of Plasma Exchange (PE) or plasma Immunoadsorption by Protein A (IA) decreased proteinuria. In this report we provide preliminary data about the prevalence of PF and the therapeutic effect of its removal by IA, in 3 pts with recurrence in the transplanted kidney, and 4 with FSGS of the native kidneys. They were resistant to corticosteroids (CS) and immunosuppressive (IS) therapy. 10 IA sessions were performed in 4 weeks: if a remission was achieved IA was gradually tapered. The level of PF in the serum was measured by an in vitro assay to determine the glomerular permeability to albumin. The FSGS was histologically proven in all cases and the degree of evolution was evaluated. PF levels, serum creatinine, daily proteinuria and serum albumin were monitored. The 3 patients with recurrent FSGS had a normalization of the PF levels; 2 had a clinical remission. In FSGS of native kidneys PF was elevated in 3/4 cases; 1 had a clinical remission; 2 with extensive sclerohyalinosis and 1 without PF levels did not improve. Our results confirm that most patients with FSGS have high PF serum levels and suggest that its removal can be beneficial.

Apheresis in primary focal segmental glomerulosclerosis of native and transplanted kidneys: a therapeutic protocol

BACKGROUND

Patients with focal segmental glomerulosclerosis (FSGS) develop nephrotic syndrome and terminal renal failure in most cases. FSGS reappears in 15-50% of transplanted kidneys and frequently causes the graft loss. Sera from patients with FSGS of native or transplanted kidneys contain some proteinuric or permeability factors (PF) which can be removed by means of plasma exchange (PE) or protein A Immunoadsorption (IA).

METHODS

We suggest a therapeutic protocol, for patients with biopsy proven FSGS of native or transplanted kidneys, resistant to steroid and immunosuppressive therapy, based on the association of PE or IA to conventional drug therapy. Daily proteinuria, renal function, serum albumin and circulating level of proteinuric factors (permeability test) will be monitored at regular time intervals during the apheresis cycle, which will be intensive at the beginning (8-10 sessions in 4 weeks) and very gradually discontinued. Results. We will consider satisfactory remission the reduction of proteinuria below 1 g/day, improvement of renal function, normalization of serum albumin level (> 3.5 g/dl). Partial remission will be considered: proteinuria below 3 g/day, stable renal function, serum albumin level between 3 and 3.5 g/dl. Permeability test, if positive at baseline examination, should be negative after apheresis.

CONCLUSIONS

The primary endpoint of our protocol is: lasting remission (satisfactory or partial) after the apheresis suspension. Secondary endpoints are: maintained remission with continuing apheresis sessions, correlation between permeability activity and disease activity, identification of responders and non responders patients on the basis of positive permeability test.

Effects of oral administration of heparan sulphate in the rat remnant kidney model

Heparins are useful for the protection of residual renal function in several nephropathies, but the anticoagulant action and the need of parenteral administration are two main drawbacks limiting their use in chronic renal failure patients. Heparan sulphate (HS) is a heparin-like mucopolysaccharide devoid of anticoagulant action and active orally. In this study, the effects of HS oral administration have been evaluated in 18 subtotally nephrectomized rats;18 untreated remnant kidney rats served as control. No mortality was observed in the HS-treated rats, whereas in the control rats the survival rate was 72.2% at 18 weeks. At the end of the study, HS-treated rats showed lower urinary protein excretion (44 +/- 22 vs. 80 +/- 54 mg/24 h, p < 0.01), lower urea plasma levels (75 +/- 34 vs. 134 +/- 105 mg/dl, p < 0.01) and higher creatinine clearance (66 +/- 15 vs. 47 +/- 21 ml/min. 10(2), p < 0.05) than control rats. Remnant kidney weight (2.3 +/- 1.1 vs. 1.3 +/- 0.2 g, p < 0.01) and heart weight (1.3 +/- 0.2 vs. 1.1 +/- 0.1 g, p < 0.05) were greater in the control than in the HS-treated rats, as well as the systemic blood pressure values (167 +/- 19 vs. 115 +/- 32 mm Hg, respectively, p < 0.001). The remnant kidney histological examination in the HS-treated rats showed a lower prevalence of glomerular sclerosis, mesangial proliferation, and a much less evident tubulointerstitial damage than in controls. The antiproliferative and anti-inflammatory actions of HS together with its protective action on the endothelium are the putative mechanisms that could account for our findings. In conclusion, the present study supports evidence of an antiproteinuric and a renoprotective effect of orally administered HS in subtotally nephrectomized rats. This is in keeping with the well-known effects exerted also by other heparins, but the effectiveness of an orally available heparin-like product in this animal model could suggest the possibility of a clinical use also in progressing chronic renal failure patients.

Routine immunofluorescence and light microscopy processing with a single renal biopsy specimen: 18 years' experience in a single centre

To obtain a correct histological renal diagnosis, two adequate cortical biopsy cylinders are routinely taken for light microscopy and immunohistology in nephrology units. We describe our simple method for light microscopy (LM) study using the same frozen renal material used for immunofluorescence (IF). Of over 2,000 biopsies processed with this method, only three showed thawing artifacts and all occurred when the room temperature was above 30 degrees C. Our 18 years' experience and the large number of biopsies indicate that this method offers an interesting new way to do LM and IF with one biopsy core and could help stimulate etiopathogenic and diagnostic studies in nephrology. The other renal specimen can be used for histological investigation, applying recent molecular biology techniques (PCR, RT-PCR, in situ hybridization).

Predictors of renal outcome in diffuse proliferative glomerulonephritis in systemic lupus erythematosus

The occurrence of nephritis is considered to be the most important factor influencing the prognosis in systemic lupus erythematosus (SLE). Despite the apparent histological similarity of the lesions, however, patients with diffuse proliferative glomerulonephritis (DPGN) may exhibit different outcomes. A retrospective study was carried out on 81 SLE patients with DPGN to evaluate the prognostic significance of different clinical, serological and histological variables; in particular, 95 renal biopsies were re-evaluated and the activity and chronicity indices for the patients were determined. A positive correlation was observed between the presence of chronic lesions on renal biopsy and a poor renal outcome (< 0.001). Moreover, in the repeat biopsies the patients with a poor outcome showed a higher degree of chronic lesions. Active lesions and other clinical and serological parameters did not correlate with the outcome.

Guidelines for the management of essential mixed cryoglobulinemia

The principal therapeutic procedures and when they are clinically indicated in the management of essential mixed cryoglobulinemia (EMC) have been the subject of much debate. This paper reviews current knowledge and our experience in the treatment of this complex disease. It is generally agreed that patients with purpura, the primary symptom of EMC, should avoid long periods of sitting or standing in the same position. Non-steroidal antiinflammatory drugs can be used for the management of arthralgias and/ or arthritis. Low dose steroids (0.5-0.3 mg/kg/die) are usually sufficient to control the purpura, arthralgias, arthritis and weakness, while larger doses (0.5-1.5 mg/kg/die) are needed to treat the renal involvement, peripheral neuropathy and serositis. Since the discovery of the association between EMC and viral infections, the appropriateness of cytotoxic drugs has been re-evaluated and they are no longer used. With the low antigen content diet, a regimen designed to restore a saturated mononuclear phagocytic system, good results have been obtained in the treatment of purpura, arthralgias, weakness and peripheral neuropathy. Furthermore, this dietary regimen may play a steroid sparing role. Plasma exchange is widely used in the management of severe renal involvement, hyperviscosity syndrome, sensory motor neuropathy and liver involvement in EMC.

Selective techniques of apheresis in polyneuropathy associated with monoclonal gammopathy of undetermined significance

Three cases affected by peripheral neuropathy associated to monoclonal gammopathy of undetermined significance (MGUS) were treated by using selective apheretic techniques, chosen on the basis of the serological characteristics of the gammopathy. Double filtration plasmapheresis was used in the first two cases, respectively affected by gammopathy of IgM type, kappa chains, and IgG type, lambda chains; protein A immunoadsorption in Case 3 with IgG type, lambda chains. Apheretic sessions were performed for three-four months, in association with low-dose immunosuppressive therapy. Clear and stable improvement of the neuropathy over 12-month follow-up period was observed both from a clinical and electrophysiological point of view. It is concluded that in peripheral neuropathy associated with MGUS selective techniques of apheresis can prove useful both in obtaining positive results and in avoiding the collateral effect of the original plasma exchange.

Cryoglobulinemic membranoproliferative glomerulonephritis associated with hepatitis C virus

A striking association between hepatitis C virus (HCV) and mixed cryoglobulinemia (MC) has been reported by various authors, regardless of the presence of chronic hepatitis. The aim of this study is to evaluate the prevalence of HCV-related markers in cryoglobulinemic membranoproliferative glomerulonephritis (MPGN) which is one of the most severe complications of MC. Antibodies against HCV have been detected by second-generation Chiron ELISA and RIBA in 26/26 (100%) cryoglobulinemic MPGN. In addition, serum HCV RNA, expression of the ongoing viral replication, was present in 7/7 patients by the polymerase chain reaction technique. The high percentage of anti-HCV seropositivity suggests that this virus may play an important role in the pathogenesis of this immunemediated glomerulonephritis.

Unusual reaction to chlorambucil: a case report

In this brief report we describe a case of cutaneous reaction during treatment of chronic lymphatic leukemia (CLL) with chlorambucil. The patient developed a confluent maculopapular erythema and large flaccid bullae of trunk, legs, feet and mucous membranes, with fever up to 38 degrees C. Toxic epidermal necrolisis (TEN) was supposed and the diagnosis was confirmed by a skin patch test followed by cutaneous biopsy. TEN by chlorambucil is a rare syndrome that may be considered in presence of cutaneous reaction to this drug.

Protection of renal function and of nutritional status in uremic rats by means of a low-protein, low-phosphorus supplemented diet

A low-protein, low-phosphorus diet supplemented with essential amino acids and keto analogues was given to 12 rats, starting from the 90th day after subtotal nephrectomy. The purpose was to assess its effect on the residual renal function and on the nutritional status in rats with already established severe renal failure. Ten control rats in the same conditions, following a standard diet supplying normal amounts of protein and phosphorus were also studied. The supplemented diet exerted a well-evident protection of residual renal function and structure: lower rate of decline of creatinine clearance, lower mortality, significant decrease of proteinuria and almost total absence of histological signs of activity. The nutritional status was also well protected by the dietary therapy: increase of body weight, normal values of total serum protein, and low-constant values of urea appearance. In the control rats body weight decreased, total serum protein was lower than normal and the values of urea appearance were increasing simultaneously with a decreasing food intake and body weight.