The dielectric behavior of nonspherical biological cell suspensions: an analytic approach.

The influence of the cell shape on the dielectric and conductometric properties of biological cell suspensions has been investigated from a theoretical point of view presenting an analytical solution of the electrostatic problem in the case of prolate and oblate spheroidal geometries. The model, which extends to spheroidal geometries the approach developed by other researchers in the case of a spherical geometry, takes explicitly into account the charge distributions at the cell membrane interfaces. The presence of these charge distributions, which govern the trans-membrane potential DeltaV, produces composite dielectric spectra with two contiguous relaxation processes, known as the alpha-dispersion and the beta-dispersion. By using this approach, we present a series of dielectric spectra for different values of the different electrical parameters (the permittivity epsilon and the electrical conductivity sigma, together with the surface conductivity gamma due to the surface charge distribution) that define the whole behavior of the system. In particular, we analyze the interplay between the parameters governing the alpha-dispersion and those influencing the beta-dispersion. Even if these relaxation processes generally occur in well-separated frequency ranges, it is worth noting that, for certain values of the membrane conductivity, the high-frequency dispersion attributed to the Maxwell-Wagner effect is influenced not only by the bulk electrical parameters of the different adjacent media, but also by the surface conductivity at the two membrane interfaces.

Ordering fluctuations in a shear-banding wormlike micellar system.

We present a first investigation about the non-linear flow properties and transient orientational-order fluctuations observed in the shear-thinning lecithin-water-cyclohexane wormlike micellar system at a concentration near to the zero-shear isotropic-nematic phase transition. From rheological measurements the stress plateau was found shifted to very low values of the applied shear rate gamma, compared to most of the concentrated living polymer systems reported in the literature. Rheo-small angle neutron scattering (Rheo-SANS) experiments performed in the flow-vorticity plane revealed periodical fluctuations of both the order parameter P(2) and the angular deviation phi from the vorticity axis as determined from the scattering peaks. The periods of the oscillations were not found to depend on imposed gamma. A theoretical model was also developed to explain the oscillatory dynamics of the shear-induced nematic order parameter in terms of the presence of standing waves of the director orientation profile along the circumference of the Couette cell. The experimental results of the periodic order parameter fluctuations together with their theoretical modelling shed significant new insights on the shear banding phenomenon, particularly its microscopic mechanism.

Autonomic neuropathy in mixed cryoglobulinemia.

A retrospective, cross-sectional study was performed on a series of HCV-related mixed cryoglobulinemia (HCV-MC) patients to assess autonomic neuropathy (AN) and its relation to peripheral neuropathy (PN). Thirty consecutive patients affected by HCV-MC underwent clinical, neurological and electrodiagnostic examinations. Autonomic nervous system (ANS) involvement was assessed by functional cardiovascular tests and sympathetic skin response (SSR) evaluation. Sural nerve biopsy was performed in 10 patients with PN. All patients received steroids, 15 also received recombinant interferon-alpha2b (RIfn-alpha2b). PN occurred in 27 patients (90.0%) and AN in 4 (13.3 %) all with signs of PN. SSR was the autonomic test more frequently altered. Biopsy disclosed axonal degeneration more evident in the 4 patients with AN. Three out of 4 patients with AN received steroids and rIFN-alpha2b and 1 steroids alone. In our study on HCV-MC, it was concluded that AN can occur also without dysautonomic symptoms, SSR appears to be one of the optional tests to use together with dysautonomic tests to identify AN and finally PN and AN do not seem to be positively influenced by addition of rIFN-alpha2b to steroid treatment.

In Vivo Near-Infrared Fluorescence Imaging of Aqueous Humor Outflow Structures.

The aim of this study has been to visualize the aqueous outflow system in patients affected by primary open angle glaucoma. A solution of indocyanine green (ICG) plus high viscosity viscoelastic solution was injected into the Schlemm canal during surgery in 10 glaucomatous patients undergoing canaloplasty. Soon after injection of the dye the borders of the scleral flap were completely stained due to partial reflux caused by the intrachannel resistance; progression of the dye along the Schlemm canal starting from the site of injection was then visualized. The filling of the collector channels was observed only in the patent portions of the Schlemm canal. The only noticeable aqueous veins were located in correspondence of the quadrant in which both the Schlemm canal and the collectors were patent. Lastly, a retrograde filling, of glomerular-shaped structures, deepest to the Schlemm canal was observed in the quadrants where the pathway was functioning. Our findings show that injection of a mixture composed of ICG and viscoelastic solution into the Schlemm canal allows a clear visualization of the functioning portions of the conventional outflow pathway. In addition, a retrograde filling of structures presumably located into the iris was also recorded. Clinical Trial Registration. Our study is registered in ISRCTN registry, number 54005880, DOI 10.1186/ISRCTN54005880.

Hyperthyroidism and Addison's disease in a patient with myotonic dystrophy.

A 53-year-old man had myotonic dystrophy, hyperthyroidism, and Addison's disease, an association not previously reported, to our knowledge. In the literature, at least five cases of hyperthyroidism associated with myotonic dystrophy have been described, but none also had Addison's disease. The presence of thyroid anti-microsomal antibodies and anti-adrenal antibodies suggests that the two endocrine disorders may be autoimmune. In our case, the treatment of the two endocrinopathies caused a reduction of myotonic symptoms.

Importance of showing HBsAg and HBcAg positivity in the liver for better aetiological definition of chronic liver disease.

Serum and tissue hepatitis B virus (HBV) markers were compared in 35 alcoholic and 23 non-alcoholic subjects affected by chronic liver disease. Seventeen point one per cent of alcoholic and 21.7% of non-alcoholic subjects had HBV tissue markers, but not serum markers, for this virus. It is therefore concluded that showing the presence of HBV tissue markers permits a better aetiological definition of hepatitis B surface antigen (HBsAg) negative chronic liver disease, both in alcoholic and non-alcoholic subjects.

Cognitive impairment in systemic lupus erythematosus: a follow-up study.

We evaluated outcome and the clinical value of cognitive impairment in systemic lupus erythematosus (SLE). Fifty-one consecutive SLE subjects with or without overt nervous system involvement received two comprehensive neuropsychiatric and neuropsychological assessments, including the Mental Deterioration Battery, the Mini Mental State Examination (MMSE), and tests from the Wechsler Adult Intelligence Scale. The two neuropsychological assessments were made when subjects were in stable neurological condition. Twenty-seven patients were found to have neuropsychiatric symptoms (NP-SLE) at the first assessment, and three others developed them during the follow-up. Fifteen patients (10 NP-SLE) had cognitive impairment at the first assessment. At retest the cognitive deficit persisted in all patients but one (non-NP-SLE) and had developed in four others. In the cognitively impaired subjects scores on MMSE approached the cutoff for an overt dementing condition. No progressively decreasing scores were found on any of the tests. No relationships were shown between neuropsychological diagnosis and neuropsychiatric disorder, neuroradiological findings, disease activity, or steroid and nonsteroid immunosuppressive therapy. Cognitive impairment thus seems to be a stable symptom of CNS involvement in SLE. It corresponds to the subjective complaint of intellectual difficulties and marginal performance on the MMSE. Intellectual deterioration may occur in patients without other symptoms of NP-SLE. Standardized neuropsychological testing methods should be used routinely to assess SLE patients.

Adult polyomyositis/dermatomyositis associated with acute myeloid leukemia. A case report.

Reports of PM/DM associated with haematologic disorders are rare. We describe a 62-year-old man suffering from PM/DM who developed acute myeloid leukemia. The possible paraneoplastic nature of PM/DM in this patient is discussed.

Infective endocarditis presenting as polyarthritis.

We report the case of a patient who complained of arthralgias and arthritis 1 month before the onset of fever or other signs of infective endocarditis. In 2 months she developed an additive, asymmetrical polyarthritis with fever (febrile polyarthritis). Splenomegaly was present. Two-dimensional echocardiography showed no vegetations or other findings suggesting endocardial involvement. Initially, four blood cultures showed no microorganisms, then six of nine subsequent blood cultures grew highly gentamicin-resistant Enterococcus faecalis.

Immunoscintigraphy as an adjunct to diagnostic imaging in septic sacroiliitis. Report of a case.

Septic sacroiliitis in childhood is a relatively rare condition. We describe a case of septic sacroiliitis occurring in an 11-year-old girl in whom the diagnosis was suspected on clinical findings and bone scan. Immunoscintigraphy with 99mTc-labelled antigranulocyte antibodies further supported the hypothesis for a septic origin of the disease. The clinical evolution clinched the diagnosis.

Electrochemical methods of evaluating the van't Hoff enthalpy in reactions involving biological macromolecules.

We highlight conditions under which coincidence of van't Hoff and calorimetric enthalpies can be experimentally verified for reactions of biochemical interest. First, we clarify that, often, chemical equations in condensed phase do not explicitly contain information on all processes involved. Second, we underline that the accuracy of electrochemical methods is much higher than that of other non-calorimetric techniques. Electrochemical data on the binding of ethidium ion to DNA are re-examined to verify that the entropy evaluated as the temperature derivative of the free energy agrees in full with the calorimetric one. Third, we point out that unfolding or self-association enthalpies of redox proteins can be reliably obtained by electromotive force measurements, taking advantage of their linkage to redox enthalpies. Thermodynamic cycles coupling biochemical transformations to redox systems are briefly discussed.

[Peripheral nervous system involvement in HCV-related mixed cryoglobulinemia] / Interessamento del sistema nervoso periferico nella crioglobulinemia mista HCV-correlata.

In HCV-related mixed cryoglobulinemia (MC) a peripheral neuropathy (PN) may occur. To evaluate the prevalence and the characteristics of PN, 133 consecutive patients with HCV-MC (117 type II, 16 type III) were studied. Neurologic evaluation was performed according to the guidelines of Italian Group for the Study of Cryoglobulinemias, using a neurological disability score and a neurological symptom score. In 52/133 patients an electrophysiologic study (ENG) of ulnar, peroneal and sural nerves was performed. For 27/52 patients ENG data registered at different times (interval 12-96 months) were available. In 11 patients a sural nerve biopsy was obtained. An overt PN, mostly as sensory asymmetrical or symmetrical nerve impairment, was found in 107/133 patients (80.4%). ENG abnormalities-reduction or absence of sensory and sometimes of motor action potential, normal or slightly impaired nerve conduction velocity, consistent with axonal damage- were detected in 48/52 patients (92.3%). In 26 out of the 27 patients observed at different times an evolution of PN was found. Nerve biopsies showed a prevalent axonal damage, swollen endothelial cells in epi- and perineurial vessels and scarce mononuclear perivascular infiltrates. No leukocytoclastic vasculitis was observed. Immunoglobulins and complement in sub-perineurial vessel wall were detected. CONCLUSIONS: In HCV-MC a PN is frequent. It is mostly a sensory and progressively worsening axonopathy. Different mechanisms may be involved in the pathogenesis of this disorder and a direct role of HCV cannot be excluded.

Dielectric response of shelled toroidal particles carrying localized surface charge distributions. The effect of concentric and confocal shells.

Dielectric models of biological cells are generally based on spherical or ellipsoidal geometries, where the different adjoining dielectric media are arranged as distinct core and shells, representing the cytosol and the cell membrane. For ellipsoidal particles, this approach implies the assumption of confocal shells that, in turn, means a cell membrane of ill-defined thickness. A quantitative analysis of the influence of a non-uniform thickness of the cell membrane has been not considered so far. In the case of a toroidal particle, this problem can be conveniently addressed by considering the solution of the Laplace equation in two different coordinate systems, i.e., toroidal coordinates (confocal shells and hence non-uniform thickness of the shell membrane) and toroidal polar coordinate, (concentric shells and hence a uniform thickness of the shell membrane). In the present paper, we compare the dielectric spectra of a toroidal particle aqueous suspension obtained from the two above stated solutions of the Laplace equation and we furnish a first quantitative estimate of the differences arising from considering the presence of confocal or concentric shells. This approach offers a complete view of the influence of the membrane thickness on the whole dielectric spectrum of a biological particle suspension, at least as far as toroidal objects are concerned.

Dielectric properties of biological cells in the dipolar approximation for the single-shell ellipsoidal model: the effect of localized surface charge distributions at the membrane interface.

In this paper, we describe the dielectric properties of a biological cell suspension of shelled ellipsoidal cells with a layer of localized charges at the membrane interfaces. In so doing, we are dealing with two different problems encountered in finding an analytical solution of the dielectric problem. The first one concerns the calculation of the electrical polarizability of a shelled ellipsoidal cell in the presence of a localized layer of charges. We will show that what we call the dipolar approximation is good enough to ensure a meaningful behavior of the dielectric spectra, whatever the cell parameters are, contrarily to what happens if one estimates the polarizability without taking into account the appropriate correction term deriving from the localized charge distribution. The second problem we face concerns the fact that the interfaces of the different adjacent media should be surfaces of constant coordinates, within a certain set of coordinate types. This implies, for ellipsoidal geometries, the requirement of a confocal condition which leads to a cell membrane of nonconstant thickness. Even if the membrane thickness is at least two orders of magnitude lower than the typical cell size, its nonconstancy leads to serious discrepancies in the shape of the dielectric spectra, which are heavier the larger the membrane conductivity is or larger as the value of the conductivity of the surface charge layers is. As far as this latter problem is concerned, we propose a compromise that saves the confocality condition and, at the same time, reduces significantly the effects of the nonuniform membrane thickness. We present here some dielectric spectra of shelled ellipsoidal cells (both prolate and oblate in shape) over an extended frequency range, showing their main characteristics, arising from the combined presence of localized charge distributions and polarization charge distributions. Finally, we compare some of these results with the ones obtained using different approximations.

Novel surfactant-based adsorbent material for groundwater remediation.

Many surfactants aggregate spontaneously in aqueous media to form small spherical structures called micelles. Among the numerous technical applications it is known that micelles have the ability to dissolve in their hydrophobic part significant amounts of water-insoluble organic compounds. In this study we investigated through UV-vis spectroscopy the micellar solubilization of 2,4,5-trichlorophenol (Tcp), an intermediate product of the microbial degradation of the broad-leaf herbicide 2,4,5-trichlorophenoxyacetic (2,4,5-T). Our results show that in the presence of the anionic surfactant sodium dodecylsulfate SDS the water solubility of Tcp increases six-fold whereas with cationic CTAB and nonionic Triton-X 100 the partition of chlorinated compound is not efficient. After the excess amount of the pollutant solubilized in SDS-micelles has been precipitated with CaCl2 the remaining fraction of Tcp has been successfully reduced within the toxicological limit for drinkable water through a cocurrent multistage operation. Finally, potential use in the decontamination of wastewater or soils of the new adsorbent material has been compared with the most commonly used activated carbon and silica gel.

The Interaction of Micelles with Added Species and Its Similarity to the Denaturant Binding Model of Proteins.

The effect of additives on micellar aggregation is treated using the same framework developed for macromolecular binding. This procedure, hinging on the pseudo-phase transition model, allows us to evaluate the binding constant of any added substance to a micellar aggregate as well as the number of particles bound per amphiphilic unit. The analysis of published literature data confirms that the model provides a general description of micellar aggregation in the presence of added ingredients, regardless of their ionic or non-ionic nature. Original data from our laboratory are well described by the suggested macromolecular binding approach. The dependence of experimental trends on micellization modifiers is also briefly discussed. Copyright 1998 Academic Press.

A case of portal thrombosis arisen after treatment with dihydroergotamine.

We describe the case of a 42 year old woman with abdominal pain, ascites, and splenomegaly after having taken dihydroergotamine continuously for three months due to frequent hemicranic episodes. The celiac-mesenteric angiography demonstrated diffuse thrombosis of splenic, superior mesenteric and portal veins. No surgical intervention was possible. We believe that it is possible that dihydroerogotamine, a hydrogenated derivative of ergotamine, inasmuch as it is capable of causing peripheral vasoconstriction, intimal lesions, arterial and venous thrombi, was also the cause of our patient's portal thrombosis. We therefore suggest the minimum effective amount of the drug be utilized to achieve the relief of cephalalgia.