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.

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.

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.

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.

[Peripheral nervous system involvement in HCV-related mixed cryoglobulinemia]

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.

Elevated bioactive prolactin levels in systemic lupus erythematosus--association with disease activity

OBJECTIVE

To assess the possibility that prolactin (PRL) is involved in the pathogenesis of systemic lupus erythematosus (SLE).

METHODS

We determined serum PRL levels in 122 serum samples from 78 unselected patients with SLE (73 women, 5 men, age range 16-71 yrs). Disease activity was defined according to Lupus Activity Criteria Count (LACC) and scored by Systemic Lupus Disease Activity Index (SLEDAI). Serum PRL concentrations were determined by immunoradiometric assay (IRMA) and by biological assay (BA) that evaluates Nb2 lymphoma cell proliferation.

RESULTS

Hyperprolactinemia (> 20 ng/ml) was found in 21 patients (26.9%) by IRMA and in 31 (39.7%) by BA. A significant correlation between IRMA and BA PRL levels was found (rs 0.46, p < 0.001). According to LACC, SLE was active in 29 patients and inactive in 49. In those with active disease median PRL levels were higher both by IRMA (18.5 ng/ml, range 2.2-51.2 vs 10.6 ng/ml, range 3.9-29.6; p < 0.001) and BA (21.0 ng/ml, range 12.4-84 vs 14.9 ng/ml, range 4.2-46.1; p < 0.001). Hyperprolactinemia was associated with active disease in 13/21 patients (61.9%) by IRMA and in 18/31 (58.1%) by BA (p < 0.01). SLEDAI scores correlated with PRL levels both by IRMA (rs 0.5, p < 0.001) and BA (rs 0.41, p < 0.02). A followup analysis on serum samples from 44 patients seen again after 6-8 mo confirmed the above results. There was no difference in the rate of different clinical manifestations in hyperprolactinemic and normoprolactinemic subjects, apart from the increased prevalence of malar rash and central nervous system manifestations in the patients with hyperprolactinemia (p < 0.03 and p < 0.01, respectively).

CONCLUSION

Hyperprolactinemia was frequently detected in patients with SLE by IRMA and by BA and was associated with disease activity. Our findings suggest that PRL may play a role in the pathogenesis of SLE.

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.

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.

Increased serum concentrations of soluble HLA-class I antigens in hepatitis C virus related mixed cryoglobulinaemia

OBJECTIVE

To investigate whether quantitative alterations of both beta(2)microglobulin (beta(2)micro) associated HLA class I heavy chains (sHLA-I) and beta(2) micro free class I heavy chains (sHLA-FHC) in sera of patients with hepatitis C virus (HCV) infection occur and whether they distinguish patients with mixed cryoglobulinaemia (MC).

METHODS

83 HCV infected patients were studied and divided into three groups: (A) without cryoglobulinaemia (n=21), (B) with polyclonal MC (n=20), (C) with monoclonal MC (n=42). Serum sHLA-I and sHLA-FHC were measured by double determinant radioimmunoassay using monoclonal antibodies: TP25.99 as catching antibody, and NAMB-1 and HC-10 as revealing antibodies. Western blot identified HLA-I isoforms.

RESULTS

The serum concentrations of sHLA-I and of sHLA-FHC in HCV infected patients versus controls were respectively 1.3(0.5) microg/ml (mean (SD)) versus 0.8 (0.3) (p<0. 001) and 13.9 (7.1) ng/ml versus 9.2 (5) (p<0.001). sHLA-I were 1.01 (0.4) microg/ml in group A, 1.04 (0.4) microg/ml in group B, and 1. 47 (0.4) microg/ml in group C (p=0.001). Statistical analysis showed a significant difference versus controls for groups B (p<0.02) and C (p<0.001). sHLA-FHC were 12.8 (8.3) ng/ml in group A, 17.2 (7.1) ng/ml in group B, and 12.9 (6.2) ng/ml in group C (p<0.02). A significant difference versus controls for each group was found (p<0. 02, p<0.001, and p<0.02, respectively). Different patterns of sHLA-I isoforms were observed.

CONCLUSIONS

Increased serum concentrations of sHLA-I and sHLA-FHC characterise HCV infected patients. The highest sHLA-I concentrations seem to distinguish patients with monoclonal MC. In this last condition sHLA could play a part in the HCV escape and in B cell proliferation. The significance of sHLA-FHC is still undefined.

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.

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.

Increased level of serum HLA class I antigens in patients with systemic lupus in patients with systemic lupus erythematosus. Correlation with disease activity

The level of soluble beta2-mu-associated HLA Class I heavy chains (sHLA-I) and of soluble beta2-mu-free HLA Class I heavy chains (sHLA-FHC) was found to be significantly higher in sera from 58 patients with systemic lupus erythematosus (SLE) than in those from 82 age and sex-matched controls. The level of serum sHLA-I in patients with SLE was significantly correlated to disease activity. Western blotting analysis showed that the 44-kDa isoform represents the major component in the antigens immunoprecipitated by anti-beta2-mu mAb NAMB-1 and by anti-beta2-mu-free HLA Class I heavy chain mAb HC-10 from sera of patients with SLE. These results suggest that the increased serum levels of sHLA-I and of sHLA-FHC in patients with SLE reflect their increased shedding from cell membrane. In view of the ability of sHLA-I and of sHLA-FHC to induce apoptosis of activated T cells, it is suggested that their increased serum levels in patients with SLE is triggered by dysregulation of the immune system leading to T-cell activation. The increased serum levels of sHLA-I and of sHLA-FHC may be used by the immune system to control the pool of activated T cells by inducing apoptosis. If this possibility is proven to be correct, modulation of the serum level of sHLA-I and of sHLA-FHC may be utilized to develop strategies to treat SLE.

An unusual case of primary systemic amyloidosis

Here we report an unusual case of primary systemic amyloidosis. The cutaneous lesions were polymorphic and included involvement of both external auditory canals. The visceral involvement was covert. Mapping of amyloid deposits was performed using scintigraphy with technetium-99m (V) dimercaptosuccinic acid ([99mTc (V)] DMSA). Therapy with melphalan, prednisone and colchicine resulted in considerable improvement.

Thermodynamic and Dynamic Properties of Micellar Aggregates of Nonionic Surfactants with Short Hydrophobic Tails

The densities and viscosities of binary aqueous mixtures of poly(ethylenoxide)hexanols [C6 H13 (OCH2 CH2 )m OH, C6 Em ] (m = 3, 4, and 5) have been studied in the micellar composition range. For the same surfactants the self-diffusion coefficients in mixtures with heavy water have been determined by the spin-echo pulsed field gradient method. The volumetric data are interpreted by means of the phase separation model, and values of the CMC, volume change, and standard free energy change of micellization are obtained. From the viscosity data the hydration numbers of the surfactant hydrophilic head in the micellar state are computed; they are in agreement with those obtained from HDO self-diffusion data. The surfactant self-diffusion data are used to calculate the apparent micelle radius and the aggregation number. The micellization parameters obtained for the different surfactants are compared and discussed.

Prevalence of alcohol problems in general practice: an experience from southern Italy

The Michigan Alcoholism Screening Test (MAST) and the response to a question about heavy alcohol consumption were used to assess the prevalence of alcohol problems in consecutive patients (77 males and 46 females) consulting a general practitioner in an urban area in the South of Italy (Castellammare di Stabia). Alcohol problems, which were defined by a cut-off score of 5 on the MAST and/or by heavy alcohol consumption (corresponding to at least 60 g of ethanol daily for males and 36 g of ethanol daily for females for at least 2 years), were identified in 54 patients [43.9%; 95% confidence interval (CI) 35.0-53.1%], 45 males (58.4%; 95% CI 46.6-69.6%) and nine females (19.6%; 95% CI 9.4-33.9%). The prevalence of MAST positive patients was 32.5% (95% CI 24.4-41.6%) in the total patient sample, 45.5% (95% CI 34.1-57.2%) among males and 10.9% (95% CI 3.6-23.6%) among females. The question about heavy alcohol consumption had a predictive negative value of 97.2% (95% CI 90.2-99.7%) and a predictive positive value of 73.1% (95% CI 59.0-84.4%) in relation to MAST positive patients. It is suggested that general practitioners should incorporate this question about heavy alcohol consumption as a screening question in order to detect alcohol problems and give advice regarding reduction of alcohol consumption.

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.

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.

Avascular osteonecrosis in patients with SLE: relation to corticosteroid therapy and anticardiolipin antibodies

Sixty-nine unselected SLE patients were studied to evaluate the prevalence of avascular osteonecrosis (AVN) and its relationship with steroid therapy and with anticardiolipin antibodies (aCL). All the patients were under treatment with corticosteroids. AVN occurred in seven occurred in seven of the 69 patients (10.14%) and was not related to corticosteroid intake. Seventeen of the 69 patients were also treated with methylprednisolone pulse therapy (MPPT) and cumulated the highest corticosteroid doses but none of them suffered from AVN. Excluding the 17 MPPT-treated SLE patients, corticosteroid intake was significantly higher in the AVN-SLE patients. Abnormal IgG and/or IgM aCL serum levels were found in two of the seven AVN-SLE patients and in 24 of the 62 non-AVN SLE, without a statistically significant difference. None of the seven AVN-SLE patients showed features of antiphospholipid syndrome. We conclude that in SLE patients a continuous high-dose steroid treatment may be considered a risk factor for AVN. On the contrary, MPPT regimen may reduce this risk. Anticardiolipin antibodies might represent an added factor which could play a role in some patients but not in all.

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.

A simple and rapid method to evaluate lymphocyte response to mitogens

A new method to evaluate lymphocyte response to mitogens is proposed. The method is based on the observation in fluorescence of the stimulated cells after their supravital staining on slides prestained with acridine orange in alcoholic solution. The results are expressed as Blast Index (IB). The method is very practical, easy to reproduce and shows a good correlation with 3H-thymidine uptake.

Detection of microorganisms in clinical specimens using slides prestained with acridine orange (AOS)

Slides prestained with acridine orange (AOS) were used for direct examination of microorganisms in clinical specimens. The method is simpler than a commonly used acridine orange stain (AO) and has the advantage of being a supravital stain. Results indicate that the AOS method is sensitive, and allows rapid detection of microorganisms, even in the specimens containing few microorganisms, e.g. cerebrospinal fluid. Moreover AOS may be the choice method for detection of Trichomonas vaginalis.

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.

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.