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Purpose: This article studies the variation of the electromagnetic parameters of a suspension of zebrafish (Danio rerio) embryos to assess its potential applications to toxicological and biomedical research areas., Materials and Methods: For this purpose, the dielectric impedance spectroscopy technique is applied to a modified coaxial line enclosing the biological suspension to be characterized in the frequency range from 100 kHz to 100 MHz. The electrical parameters of the suspension under test were obtained by fitting the impedance spectra to the resulted from the simulation of the test fixture using finite elements (FE)., Results: Variation of the complex permittivity of the suspensions makes possible to identify viable and non-viable embryos after a toxic exposure, as well as different stages during the blastula period of embryonic development of the zebrafish., Conclusions: The approach presented here, combining experimental and simulation techniques, may provide a basis for a non-invasive method to assess toxicity in any biological suspension.

We conducted a cluster-randomized trial to estimate effects of directly observed combination antiretroviral therapy (DOT-cART) on retention with viral suppression among HIV-positive adults in Peru. We randomly allocated facilities to receive the 12-month intervention plus the standard of care, including adherence support provided through accompaniment. In the intervention arm, health workers supervised doses, twice daily, and accompanied patients to appointments. Among 356 patients, intention-to-treat analyses showed no statistically significant benefit of DOT, relative to no-DOT, at 12 or 24 months (adjusted probability of primary outcome: 0.81 vs. 0.73 and 0.76 vs. 0.68, respectively). A statistically significant benefit of DOT was found in per-protocol and as-treated analyses at 12 months (0.83 for DOT vs. 0.73 for no DOT, p value: 0.02 per-protocol, 0.01 as-treated), but not 24 months. Rates of retention with viral suppression were high in both arms. Among adults receiving robust adherence support, the added effect of time-limited DOT, if any, is small-to-moderate.

The aim of this study is to calculate the membrane elastic energy for the different shapes observed in the discocyte-stomatocyte sequence. This analysis can provide a better quantitative understanding of the hypothesis put forward over the last decades to explain how red blood cells produce and maintain their typical shape. For this purpose, we use geometrical models based on parametric equations. The energy model considered for the elastic properties of RBC membrane includes the local and nonlocal resistance effects of the bilayer to bending. In particular, the results confirm the discocyte as the lowest energy value configuration among the sets of different red blood cell deformations considered in the sequence., (© 2013.)

We examined the relationship between food insufficiency and antiretroviral therapy (ART) adherence. A cohort of HIV-infected adults in urban Peru was followed for a two-year period after ART initiation. ART adherence was measured using a 30-day self-report tool and classified as suboptimal if <95% adherence was reported. We conducted a repeated measures cohort analysis to examine whether food insufficiency was more common during months of suboptimal adherence relative to months with optimal adherence. 1,264 adherence interviews were conducted for 134 individuals. Participants who reported food insufficiency in the month prior to interview were more likely to experience suboptimal adherence than those who did not (odds ratio [O.R.]:2.4; 95% confidence interval [C.I.]:1.4, 4.1), even after adjusting for baseline social support score (O.R. per 5 point increase:0.91; C.I.:[0.85, 0.98]) and good baseline adherence self-efficacy (O.R.:0.25; C.I.:[0.09, 0.69]). Interventions that ensure food security for HIV-infected individuals may help sustain high levels of adherence.

We use the Maxwell stress tensor to calculate the dielectrophoretic force and electrorotational torque acting on a realistic four-shelled model of the yeast Saccharomyces cerevisiae in a nonuniform rotating electric field generated by four coplanar square electrodes. The comparison of these results with numerical calculations of the dipolar and quadrupolar contributions obtained from an integral equation for the polarization charge density shows the effect of the quadrupole contribution in the proximity of the electrode plane. We also show that under typical experimental conditions the substitution of the multilayered cell by an equivalent cell with homogeneous permittivity underestimates the quadrupole contribution to the force and torque by 1 order of magnitude.

Objective: To analyze the evolution of published scientific articles on HIV/AIDS in Peru., Methods: A bibliometric analysis of papers on HIV/AIDS published in journals indexed in MEDLINE, SciELO and LILACS until October 2010. We selected research papers fully developed in Peru, and multicenter studies with participating Peruvian sites., Results: We identified 257 publications on HIV/AIDS, showing an increase since 2003. The average publication delay was 2.8±1.8 years. Only 94 (36.6 %) articles were published in Spanish. The most studied areas were epidemiology (36.6 %) and clinical topics (35.8 %). The cross-sectional design was the most frequent (56.8 %) followed by case series. According to the WHO classification, studies to learn more about the disease and risk factors predominated (85.6 %) and according to the intervention areas, 46.7 % focused on diagnosis and treatment. Most studies were conducted in Lima (65.9 %). 48.2 % of studies focused on people living with HIV/AIDS. Finally, Revista Peruana de Medicina Experimental y Salud Pública was the journal that published most articles on HIV/AIDS (9.7 %)., Conclusions: We found a growth in scientific production on HIV/AIDS in Peru; however, we believe that the research undertaken was not based on an agreed national agenda or national research priorities, which might have limitted its dissemination and application.

Progress in microelectrode-based technologies has facilitated the development of sophisticated methods for manipulating and separating cells, bacteria, and other bioparticles. For many of these various applications, the theoretical modeling of the electrical response of compartmentalized particles to an external field is important. In this paper we address the analysis of the interaction between cells immersed in rf fields. We use an integral formulation of the problem derived from a consideration of the charge densities induced at the interfaces of the particle compartments. The numerical solution by a boundary element technique allows characterization of their dielectric properties. Experimental validation of this theoretical model is obtained by investigating two effects: (1) The influence that dipolar "pearl chaining" has on the dielectrophoretic behavior of human T lymphocytes and (2) the frequency variation of the spin and orbital torques of approaching insulinoma beta-cells in a rotating field.

We predict the complex polarizability of a realistic model of a red blood cell (RBC), with an inhomogeneous dispersive and anisotropic membrane. In this model, the frequency-dependent complex electrical parameters of the individual cell layers are described by the Debye equation while the dielectric anisotropy of the cell membrane is taken into account by the different permittivities along directions normal and tangential to the membrane surface. The realistic shape of the RBC is described in terms of the Jacobi elliptic functions. To calculate the polarizability, we evoke the effective dipole moment method to determine the cell internal electric field distribution, employing an adaptive finite-element numerical approach. We have furthermore investigated the influence of the anisotropic membrane and dispersive electrical parameters of each individual cell layer on the total complex polarizability. Our findings suggest that the individual layer contribution depends on two factors: the volume of the layer and the associated induced electric field, which in turn is influenced by other layers of the cell. These results further show that the average polarizability spectra of the cell are significantly impacted by the anisotropy and associated dispersion of the cellular compartments.

The aim of this study is to analyze the electromagnetic energy stored in stomatocyte, erythrocyte and echinocyte cells exposed to a linearly polarized electromagnetic plane wave at 900, 1800 and 2450MHz radiofrequency signals. This analysis can provide a better understanding of the order of appearance of altered shapes of erythrocytes (RBC) in the stomatocyte-echinocyte transition under radiofrequency exposure in terms of the deposited electromagnetic energy. For this purpose we use a realistic geometrical cell model based on parametric equations that allow for continuous transformations between normal erythrocytes and three stomatocyte subclasses with different degree of invagination and also between normal erythrocytes and echinocytes with an arbitrary number of spicules. We use a finite element technique with adaptive meshing for calculating the electromagnetic energy deposited on the different regions of the cell models. It is found that the echinocyte cell stores the minimum electromagnetic energy and therefore from an energetic point of view it would be the most stable and preferred cell state when this electromagnetic energy is the predominant energy component., (2009 Elsevier B.V. All rights reserved.)

We show that within the dipole approximation the complex polarizability of shelled particles of arbitrary shape can be written as the volume of the particle times a weighted average of the electric field in the particle, with weights determined by the differences in permittivities between the shells and the external, possibly lossy media. To calculate the electric field we use an adaptive-mesh finite-element method which is very effective in handling the irregular domains, material inhomogeneities, and complex boundary conditions usually found in biophysical applications. After extensive tests with exactly solvable models, we apply the method to four types of hematic cells: platelets, T-lymphocytes, erythrocytes, and stomatocytes. Realistic shapes of erythrocytes and stomatocytes are generated by a parametrization in terms of Jacobi elliptic functions. Our results show, for example, that if the average polarizability is the main concern, a confocal ellipsoid may be used as a model for a normal erythrocyte, but not for a stomatocyte. A comparison with experimental electrorotation data shows quantitatively the effect of an accurate geometry in the derivation of electrical cell parameters from fittings of theoretical models to the experimental data.

We have studied the influence of the anisotropic and dispersive nature of the red blood cell structure on the energy absorption and electric field distribution within the cell exposed to electromagnetic fields of frequencies in the range from 50 kHz to 10 GHz. For this purpose we have generated a realistic model of a multilayered erythrocyte cell from a set of parametric equations in terms of Jacobi elliptic functions. The effect of dipole relaxations and anisotropic conductivities is taken into account in the dispersion equations for the conductivity and permittivity of each layer (cytoplasmic and extra-cellular bound waters, membrane, cytoplasm and external medium). Using a finite element numerical technique, we have found that the electric field distribution and the energy absorbed in the membrane show well-defined maxima for both normal and parallel orientations of the external field with respect to the symmetry axis of the cell. The normal and tangential conductivities and permittivities of the membrane are shown to be responsible for the different peak amplitudes and frequency shifts of the maxima. A previously unnoticed effect is that the cell shape combined with the dispersion of the membrane permittivity and the influence of bound water layers leads to a very high amplification factor (greater than 300) of the electric field in the membrane at frequencies in the megahertz range.

Measurements of dielectrophoretic collection spectra of Escherichia coli and Staphylococcus aureus suspensions are used for obtaining dielectric characteristics of both types of bacteria. The experiments are interpreted using a numerical method that models the cells as compartmented spherical or rod-like particles. We show the usefulness of this simple method to extract significant information about the electrical properties of Gram-negative and -positive bacteria.

We calculate the induced electric stress forces on transient hydrophobic pores in the membrane of an erythrocyte exposed to an electric field. For this purpose, we use a finite element numerical technique and a realistic shape for the biconcave erythrocyte represented by a set of parametric equations in terms of Jacobi elliptic functions. The results clearly show that the electrical forces on the base and sidewalls of the pore favour the opening of the pore. A comparison of the force densities obtained for an unstretched flat membrane and for the realistic erythrocyte model shows that the thinning and curvature of the membrane cannot be neglected. We also show that the pore deformation depends strongly on the orientation of the pore with respect to the external field, and in particular is very small when the field is tangent to the membrane surface.

We present simple parametric equations in terms of Jacobi elliptic functions that provide a realistic model of abnormal variations in size which maintain the biconcave shape of a normal erythrocyte (anisocytosis) and abnormal variations in shape which maintain the original volume of the erythrocyte (poikilocytosis), as well as continuous deformations from the normal to the altered shapes. We illustrate our results with parameterizations of microcytes, macrocytes, and stomatocytes, and we apply these parameterizations to the numerical calculation of the induced transmembrane voltage in microcytes, macrocytes, and stomatocytes exposed to an external electromagnetic field of 1800 MHz.

We study the influence of an external electromagnetic field of 1.8 GHz in the formation or disaggregation of long rouleau of identical erythrocyte cells. In particular we calculate the variation of the transmembrane potential of an individual erythrocyte illuminated by the external field due to the presence of the neighboring erythrocytes in the rouleau, and compare the total electric energy of isolated cells with the total electric energy of the rouleau. We show that the polarization of the external electromagnetic field plays a fundamental role in the total energy variation of the cell system, and consequently in the formation or disaggregation of rouleau.

In this article, the transmembrane voltage induced on erythrocyte, codocyte, ovalocyte and spherocyte cell models exposed to a linearly polarised electromagnetic plane wave of frequency 1800 MHz is calculated. For this purpose, a finite element (FE) numerical technique with adaptive meshing is used. The results show that the value of the induced voltage on the original erythrocyte shape is higher than the one observed on the rest of the altered cell geometries studied. The erythrocyte shape and the membrane electric permittivity are shown to play a fundamental role on the values of the induced transmembrane voltage.

This paper studies the internal electric field distribution in human erythrocytes exposed to MW radiation. For this purpose, an erythrocyte cell model is exposed to linearly polarized electromagnetic (EM) plane waves of frequency 900 MHz and the electric field within the cell is calculated by using a finite element (FE) technique with adaptive meshing. The results obtained show the dependence of the induced electric field distribution on the main modelling parameters, i.e., the electrical properties (permittivity and conductivity) of the membrane and cytoplasm and the orientation of the cell with respect to the applied field. It is found that for certain orientations, the field amplification within the membrane of the erythrocyte shape cell can be higher than the one observed in an equivalent simple spheroidal geometry cell, commonly used in bioelectromagnetism. The present work shows that a better insight of the interaction of electromagnetic fields with basic biological structures is obtained when the most possible realistic cell shape is used.

This paper shows the importance of using realistic cell shapes with the proper geometry and orientation to study the mechanisms of direct cellular effects from radiofrequency (RF) exposure. For this purpose, the electric field distribution within erythrocyte, rod and ellipsoidal cell models is calculated by using a finite element technique with adaptive meshing. The three cell models are exposed to linearly polarized electromagnetic plane waves of frequencies 900 and 2450 MHz. The results show that the amplification of the electric field within the membrane of the erythrocyte shape cell is more significant than that observed in other cell geometries. The results obtained show the dependence of the induced electric field distribution on frequency, electrical properties of membrane and cytoplasm and the orientation of the cell with respect to the applied field. The analysis of the transition of an erythrocyte shape to an ellipsoidal one shows that a uniformly shelled ellipsoid model is a rough approximation if a precise simulation of bioeffects in cells is desired.

Objectives: To determine the efficacy of a three-fold reduced dose (RD, 27 mg) of intravesical bacille Calmette-Guérin (BCG) against the standard dose (81 mg) in patients with superficial bladder cancer, assessing recurrence, progression and differences in toxicity., Patients and Methods: Five hundred patients with superficial bladder cancer (Ta, T1, Tis) were enrolled and randomly assigned to be treated after transurethral resection of all visible lesions with intravesical BCG Connaught strain (weekly x six and thereafter fortnightly x six) either with the standard or RD instillation., Results: All but one of the 500 patients were evaluable for efficacy and toxicity (252 in the standard arm and 247 in the RD arm). The median follow-up was 69 months (maximum 104); 71 (28%) patients in the standard arm and 76 (31%) in the RD arm developed recurrences; the median time to recurrence has not yet been attained, but at 5 years the mean (sd) percentage of recurrence-free patients was 70.5 (3.12) and 70.4 (3.1) for the standard and RD arms, respectively. In patients presenting with multifocal tumours, the standard dose was more effective against recurrences than the RD (P=0.0151). In those with G3 and high-risk tumours overall, the superiority of the standard dose was marginal (P=0.060 and P=0.082). Twenty-nine (11.5%) tumours in the standard arm and 33 (13.3%) in the RD arm progressed to invasive disease; the median time to progression has not yet been attained, but the percentage of progression-free patients at 5 years was 88.8 (2.23) and 86.9 (2.31) for the standard and RD arms, respectively. The standard dose was more effective than the RD against progression only in patients with multifocal disease (P=0.048). Twelve (4.8%) cystectomies were performed in the standard and 15 (6.1%) in the RD arm. Currently, 106 (21.2%) patients have died, but only 38 (7.6%) from bladder cancer, i.e. 20 (7.9%) in the standard and 18 (7.5%) in RD arm. Overall the disease-specific death rate was lower for those patients who completed the scheduled treatment. The cause-specific survival at 5 years did not differ between the arms (P=0.76) but there was a trend toward better cause-specific survival for patients with multifocal tumours in the standard arm. Toxicity differed between the arms, significantly more patients having no toxicity in the RD arm, and fewer having delayed instillations or withdrawing. However, severe systemic toxicity occurred even in patients treated with the RD, in a similar proportion to those receiving the standard dose., Conclusion: Overall, the RD gave similar results for recurrence and progression but with significantly less toxicity. However, patients with multifocal tumours fared better with the standard dose and there was a trend towards better recurrence rates in patients with high-risk tumours. We recommend continuing to use the standard dose for high-risk tumours, while we consider the reduced dose safe and effective for intermediate-risk lesions and for maintenance schedules.

This paper shows the importance of using a cell model with the proper geometry, orientation and internal structure to study possible cellular effects from direct radiofrequency exposure. For this purpose, the electric field intensity is calculated, using the finite element numerical technique, in single- and multilayer spherical, cylindrical and ellipsoidal mammalian cell models exposed to linearly polarized electromagnetic plane waves of frequencies 900 and 2450 MHz. An extensive analysis is performed on the influence that the cell geometry and orientation with respect to the external field have in the value of the electric field induced in the membrane and cytoplasm. We also show the significant role that the cytoplasmic and extracellular bound water layers play in determining the electric field intensity for the cylindrical and ellipsoidal cell models. Finally, a study of the mutual interactions between cells shows that polarizing effects between cells significantly modify the values of field intensity within the cell.

We present a review of the treatments of the urinary calculations carried out in the Lithotrity Unit in its first five years of working with the Dornier lithotriptor MFL-5000. We describe the location and size of the calculations, distribution by age and sex of the patients, energy applied and time employed, and we compare our retreatment index and the number of sessions per calculation with those published by other authors.

We present a case of hypercalcemia associated with a renal pelvis squamous neoplasm. Severe hyperleukocytosis was also present, resembling a leukaemoid reaction. After failure of standard therapy, we performed a trial of low dose epirubicin in this patient, obtaining a short-term clinical remission. Although a palliative non-toxic effect seems to be achievable with this approach, further studies are needed to ascertain the role of chemotherapy in the long-term control of this condition.

Sclerosant therapy for different pathological conditions (testicular hydrocele, pneumothorax) is a little known and scantily used procedure in the clinical setting. We have developed a surgical procedure in the dog that permits reproducing adult hydrocele. This experimental model is useful for morphometric assessment of the sclerosant effects of the commonly used agents (magnesium silicate hydrate, carbolic acid, ethanolamine oleate, hydroxytetracycline chlorhydrate and quinacrine chlorhydrate). Our results show that the degree of sclerosis achieved with quinacrine and hydrotetracycline is significantly superior to that obtained with other agents.

We present a case of a double left ureter, one of which branched with one blind branch, which has not been described in the literature.

A case is presented of spontaneous rupture in a pathological bladder. The authors point out the importance of retrograde cystographies to reveal intraperitoneal ruptures in te bladder and to check for the existence of associated lesions. A review is made of the etiology, clinical picture and treatment of spontaneous, intraperitoneal rupture of the bladder.