Gold nanoparticles as enablers of cell membrane permeabilization by time-varying magnetic field: influence of distance and geometry.

This study is based on the quantification of the influence of the presence of gold nanoparticles (Au NPs), of their geometry and their distance from cell membrane during time-varying electromagnetic fields cell membrane permeabilization on the pores opening dynamics. Results showed that the combined use of Au NPs and time-varying magnetic field can improve significantly the permeabilization of cell membrane. The presence of Au NPs allowed to reach transmembrane potential values enabling the cell membrane permeabilization only when placed at very short distance, equal to 20 nm. Both geometry and variability of the positioning in proximity of the cell membrane showed a strong influence on the probability of enabling pores opening. Clinical Relevance- This study provides a better comprehension about the mechanisms, still not completely understood, underlying cell membrane permeabilization by combining Au NPs and time-varying magnetic fields.

Computational Evaluation of Combined Cerebellar and Frontal Transcranial Direct Current Stimulation for Treatment-Resistant Depression.

This work aimed to estimate the distribution of the electric field generated by a combined cerebellar and frontal transcranial direct current stimulation (tDCS) for treatment-resistant depression using electromagnetics computational techniques applied to a realistic head human model. Results showed that the stronger electric fields occur mainly in the cerebellum and in DLPFC areas, where the two pairs of electrodes were applied. Furthermore, the study demonstrated that the simultaneous use of the two pairs of electrodes did not imply a lower effectiveness of the tDCS technique, in fact the electric field distributions in the primarily targets of the anatomical regions (i.e., cerebellum and DLPFC) were very similar to when the pairs of electrodes were applied separately.

Contactless Cell Permeabilization by Time-Varying Magnetic fields: Modelling Transmembrane Potential and Mechanical Stress in in- vitro Experimental Set-Up.

The feasibility of using time-varying magnetic field as a contactless cells permeabilization method was demonstrated by experimental results, but the underlying mechanism is still poorly understood. In this study a numerical analysis of the transmembrane potential (TMP) at cell membranes during permeabilization by time-varying magnetic fields was proposed, and a first quantification of mechanical stress induced by the magnetic and electric fields and hypothesized to play an important role in the permeabilization mechanism was carried out. TMP values induced by typical in-vitro experimental conditions were far below the values needed for membrane permeabilization, with a strong dependence on distance of the cell from the coil. The preliminary assessment of the mechanical pressure and potential deformation of cells showed that stress values evaluated in conditions in which TMP values were too low to cause membrane permeabilization were comparable to those known to influence the pore opening mechanisms.Clinical Relevance- Results represent a significant step towards a better comprehension of the mechanism underlying cell membrane permeabilization by time-varying magnetic fields.

Application of Stochastic Dosimetry for assessing the Human RFEMF Exposure in a 5G indoor Scenario.

In recent years the introduction of 5G networks is causing a drastically change of human exposure levels in the radio frequency range. The aim of this paper is on expanding the knowledge on this issue, assessing the exposure levels for a particular case of indoor 5G scenario, where the presence of an Access Point (AP) was simulated. Coupling the traditional deterministic computational method with an innovative stochastic approach, called Polynomial Chaos Kriging, allowed to evaluate the exposure variability of an user considering the 3D beamforming capability of the antenna. The exposure levels, expressed in terms of specific absorption rate (SAR) in specific tissues, showed low values compared to ICNIRP guidelines.

Cell transmembrane potential in contactless permeabilization by time-varying magnetic fields.

BACKGROUND: Although experimental results proved the feasibility of using time-varying magnetic field as a contactless cells permeabilization method, the underlying mechanism is still poorly understood. In this study a numerical analysis of the time-dependent transmembrane potential (TMP) at cell membranes during permeabilization by time-varying magnetic fields was proposed, and a first quantification of mechanical stress induced by the magnetic and electric fields, hypothesized to play an important role in the permeabilization mechanism, was carried out. METHODS: Starting from the simulation of real in vitro experimental conditions, the analysis was widened quantifying the influence of pulse frequency, cell dimension and distance of the cell from the magnetic field source. The mechanical pressure on cell membrane due to the interaction between free charges and induced electric field and due to the gradient of the magnetic field was quantified in all those conditions in which the TMP values were not high enough to cause membrane permeabilization. RESULTS: TMP values induced by typical in-vitro experimental conditions were far below the values needed for membrane permeabilization, with a strong dependence on pulse frequency and distance of the cell from the coil. CONCLUSION: The preliminary assessment of the mechanical pressure on cell membrane showed that stress values evaluated in conditions in which TMP values were too low to cause membrane permeabilization were comparable to those known to influence the pores opening mechanisms. Results represent a significant step towards a better comprehension of the mechanism underlying cell membrane permeabilization by time-varying magnetic fields.

Testing time-, ignorance-, and danger-based models of tolerance.

In this study, we present data showing that tolerance to Ags in the periphery is not determined by the time at which the Ag appears, or by special properties of tissues in newborn mice or newly developing immune systems. We placed male grafts onto immunoincompetent female mice, allowed the grafts to heal for up to 5 mo, and then repopulated the recipients with fetal liver stem cells. We found that the newly arising T cells were neither tolerant nor ignorant of the grafts, but promptly rejected them, though they did not reject female grafts, nor show any signs of autoimmunity. We also found that the H-Y Ag was continuously cross-presented on host APCs, that this presentation was immunogenic, not tolerogenic, and that it depended on the continuous presence of the graft. In searching for the stimulus that might activate the host APCs, we analyzed mRNA expression with a highly sensitive real-time quantitative PCR assay. By using two different "housekeeping" molecules for comparison, we analyzed the message levels for several stress and/or inflammatory molecules in the healed grafts. We found that the long-healed grafts were not equivalent to "normal" skin because the healed grafts expressed lower levels of GAPDH. Altogether, these data suggest that acceptance vs rejection of peripheral tissues is not attributable to ignorance, timing-based tolerance, or special circulation properties of naive T cells in neonatal tissues. It is more likely attributable to an aspect of the context of Ag presentation that remains to be identified.

Danger signals: SOS to the immune system.

The activation of dendritic cells, necessary for the initiation of primary and secondary immune responses, can be induced by endogenous danger signals - released by tissues undergoing stress, damage or abnormal death - and also by exogenous danger signals elaborated by pathogens. Some endogenous danger signals that recently have been discovered are heat-shock proteins, nucleotides, reactive oxygen intermediates, extracellular-matrix breakdown products, neuromediators and cytokines like the IFNs. We propose that allergy may be initiated by the direct damage of dendritic or other cells by toxic chemicals and allergenic proteases, and suggest that the triggering of danger signal receptors by exogenous pathogen-derived molecules may be more to the advantage of the pathogen than to the host.

Natural adjuvants: endogenous activators of dendritic cells.

Dendritic cells, the most potent antigen-presenting cells, need to be activated before they can function to initiate an immune response. We report here that, in the absence of any foreign substances, dendritic cells can be activated by endogenous signals received from cells that are stressed, virally infected or killed necrotically, but not by healthy cells or those dying apoptotically. Injected in vivo with an antigen, the endogenous activating substances can function as natural adjuvants to stimulate a primary immune response, and they may represent the natural initiators of transplant rejection, spontaneous tumor rejection, and some forms of autoimmunity.

Myoblasts produce IL-6 in response to inflammatory stimuli.

Muscle fibers are the target of T cell-mediated cytotoxic reactions in polymyositis and inclusion body myositis, while the success of myoblast transplantation depends on the absence of an immune rejection against the myofibers. In order to study the behaviour of muscle cells in an inflammatory milieu, we investigated the production of IL-6 and its modulation, including the second messenger pathways controlling it, in in vitro highly purified human myoblast cultures. We found that IL-1beta, tumor necrosis factor (TNF)-alpha and lipopolysaccharide (LPS) stimulated myoblast IL-6 secretion in a dose- and time-dependent manner, whereas forskolin and cholera toxin did not. HA1004 at 10 microM did not significantly affect the IL-1beta- and TNF-alpha-induced IL-6 secretion, suggesting that cAMP and protein kinase A are not sufficient to stimulate this process. To investigate the role of protein kinase C (PKC) in this signal transduction, we employed the inhibitor calphostin C, and the activators phorbol-12-myristate-13-acetate (PMA) and calcium ionophore A23187. Calphostin C blocked IL-6 secretion, PMA had a small stimulatory effect and A23187 had no effect; moreover, PKC down-regulation by PMA did not inhibit IL-1beta stimulation, while it reduced TNF-alpha stimulation. These data indicate that different PKC isoforms may be involved in TNF-alpha and IL-1beta signal transduction. Such a difference can distinguish the action of two traditionally 'overlapping' inflammatory cytokines. Our data suggest that muscle cells, like myoblasts, satellite cells and in vivo regenerating myofibers, may discriminate between different stimuli and produce IL-6 when activated in response to muscle injury.

Liver biopsy in neonatal cholestasis: a review on statistical grounds.

The aim of this study was to improve the accuracy of the histopathologic diagnosis in the differential diagnosis between obstructive and nonobstructive forms of neonatal cholestasis, using this clinical situation as a model for a mathematical approach. The study was blind, and we performed it in two steps. In the first step, 49 histologic parameters were visually estimated and were scored on a scale of 0 to 4+ in 100 liver biopsy specimens obtained between 1980 and 1985 from 78 patients with neonatal cholestasis. Forty-eight of these 100 specimens were from patients with final diagnosis of obstructive cholestasis (Group I), and 52 were from patients with nonobstructive cholestasis (Group II). The age range was 3 to 24 weeks (median, 12.5 wk). Twelve histologic variables were selected by chi 2 and Fisher's exact test (P < .05). Next, a series of combinations among these variables were submitted to statistical analysis by logistic regression method, defining a six-variable model that had the most powerful predictive value to classify the type of cholestasis. The variables were portal ductal proliferation, bile plugs in portal bile ductules, portoportal bridges, neutrophils, hepatocyte swelling, and multinucleated giant hepatocytes. The score obtained by this model correspond to the probability of a case belonging to Group I. The accuracy, sensitivity, and specificity rates were 94.0%. In the second step, the model was applied to a new sample of 74 needle-liver biopsy specimens obtained between 1990 and 1995, 45 from patients in Group I and 29 from patients in Group II. The age range was 3 to 15 weeks (median, 8 wk). The accuracy, sensitivity, and specificity rates were 90.5%, 100%, and 75.9%, respectively. In our diagnostic routine, this score has been systematically reported and has been helpful in orienting the therapeutic decision in this group of patients.

MHC class I, MHC class II and intercellular adhesion molecule-1 (ICAM-1) expression in inflammatory myopathies.

We investigated the relationship between the MHC-I, MHC-II and intercellular adhesion molecule-1 (ICAM-1) expression on myofibres and the presence of inflammatory cells in muscle specimens of 18 patients with inflammatory myopathies (nine polymyositis, seven dermatomyositis, two inclusion body myositis). We observed MHC-I expression in muscle fibres, infiltrating mononuclear cells and endothelial cells in every specimen. In seven patients, some muscle fibres were MHC-II-positive for the DR antigen, while the DP and DQ antigens were absent. ICAM-1 expression, detected in seven patients, was found in clusters of myofibres, associated with a marked MHC-I positivity and a widespread mononuclear infiltration. Most of the ICAM-1-positive fibres were regenerating fibres. Furthermore, some fibres expressed both ICAM-1 and DR antigens near infiltrating cells. This finding could support the hypothesis that myofibres may themselves be the site of autosensitization.

[Infective endocarditis: analysis of 300 episodes]. / Endocardite infecciosa: análise de 300 episódios.

PURPOSE: Study of clinical features and etiologic agents, treatment and mortality of patients with infective endocarditis (IE). PATIENTS AND METHODS: 300 episodes of IE occurring in 288 patients, ages ranged between 0.2 and 78 (mean 30.76) years; 185 (62%) episodes occurred in males. RESULTS: a) etiologic agents: viridans group streptococci in 93 (31%) episodes, enterococci en 21 (7%), group D-non enterococci in 19 (6%) (13 S. bovis), other streptococci in 14 (5%), Staphylococcus aureus in 59 (20%), Staphylococcus epidermidis in 14 (5%), gram-negative bacteria in 16 (5%), gram-positive bacteria other than streptococci and staphylococci and staphylococci in 8 (3%), fungi in 4 (1%). The etiologic agents were not identified in 52 (17%) episodes; b) underlying cardiac diseases: valvular heart disease in 119 (40%) episodes, congenital heart disease in 37 (12%), prosthetic heart valves in 69 (23%), other heart diseases in 6 (2%). There was no evidence of previous heart disease in 69 (23%); c) treatment: surgical treatment was undertaken in 102 (34%) episodes. The frequency of surgical treatment in relation to the etiologic agents ranged between 1% (non-group D streptococcus) and 62% (negative blood cultures). The frequency of operation in relation to underlying heart disease ranged between 17% (other heart diseases), 19% (congenital heart disease) and 54% (prosthetic heart valve); d) mortality: 78 (26%) patients died, 56 (28%) of the 198 submitted to medical treatment and 22 (21%) of the 102 submitted also to surgical treatment. The mortality in the different groups of etiologic agents ranged between 5% (non group D streptococcus) and 62% (gram-positive bacteria other than streptococci ans staphylococci); in relation to the underlying with other heart disease, 19% in valvular heart disease patients, 21% in patients with congenital heart disease, 23% in patients without known heart disease and 43% in patients with prosthetic heart valves. CONCLUSION: The mortality associated with IE remains still high in spite of modern treatment; the mortality is different in relation to the cardiac status before the IE.

Liver morphology with enphasis on bile ducts changes and survival analysis in mice submitted to multiple Schistosoma mansoni infections and chemotherapy

Numa tentativa de estar o mais próximo possível a pacientes infectados e tratados nas áreas endêmicas de esquistosomose (S. mansoni) e também para obter um período mais longo de seguimento, camundongos foram repetidamente infectado com um número baixo de cercarias. Dados de sobrevivência e variáveis histológicas tais como granuloma esquistosomótico, alteraçöes portais, necrose hepatocelular, regeneraçäo hepática, pigmento esquistosomótico, fibrose periductal e principalmente, alteraçöes dos ductos biliares foram analisados nos animais infectados tratados e näo tratados. Aa terapêutica por oxamniquina ns animais repetidamente infectados prolonga a sobrevivência de maneira singificante (Chi-quadrado 9,24, p = 0,0024), portanto confirmando resultados anteriores com um modelo semelhante mas com um período mais curto de seguimento. Ainda, a mortalidadade decresce rapidamente depois do tratamento, sugerindo uma abrupta reduçäo na gravidade das lesöes hepáticas. O fígado foi anida estudados sob o ponto de vista morfológico imunohistoquímico. Fibrose portal, com um quadro que lembra a fibrose humana do tipo Symmers está presente na fase tardia da infecçäo. As alteraçöes de ductos biliares säo muito próximas daquelas descritas na esquistosomose manônica humana. Antígeno esquistomótico foi observado e, uma célula isolada do revestimento alterado de ductos biliares. A patogênese das alteraçöes ductais e sua possível relaçäo com a infecçäo parasitária e/ou seus antígenos foi discutida

Liver morphology with emphasis on bile ducts changes and survival analysis in mice submitted to multiple Schistosoma mansoni infections and chemotherapy.

In an attempt to be as close as possible to the infected and treated patients of the endemic areas of schistosomiasis (S. mansoni) and in order to achieve a long period of follow-up, mice were repeatedly infected with a low number of cercariae. Survival data and histological variables such as schistosomal granuloma, portal changes, hepatocellular necrosis, hepatocellular regeneration, schistosomotic pigment, periductal fibrosis and chiefly bile ducts changes were analysed in the infected treated and non treated mice. Oxamniquine chemotherapy in repeatedly infected mice prolonged survival significantly when compared to non-treated animals (chi-square 9.24, p = 0.0024), thus confirming previous results with a similar experimental model but with a shorter term follow-up. Furthermore, mortality decreased rapidly after treatment suggesting an abrupt reduction in the severity of hepatic lesions. A morphological and immunohistochemical study of the liver was carried out. Portal fibrosis, with a pattern resembling human Symmers fibrosis was present at a late phase in the infected animals. Bile duct lesions were quite close to those described in human Mansonian schistosomiasis. Schistosomal antigen was observed in one isolated altered bile duct cell. The pathogenesis of the bile duct changes and its relation to the parasite infection and/or their antigens are discussed.

[Incidence of dyslipidemia and its relation to coronary artery disease in Brazilian populations]. / Incidência de dislipidemia e sua relação com doença arterial coronária em populações brasileiras.

PURPOSE: To describe the incidence of dyslipidemia and its relation to coronary artery disease (CAD) in two brazilian populations. PATIENTS AND METHODS: 1.261 subjects were analyzed; 674, whose mean age was 53 years, came from a cardiology private office (population A) and 587, whose mean age was 37 years, were employees of an engineering company (population B). Cholesterol was determined by the enzymatic method Chod-pap and LDL calculated by the Friedwald's formula. RESULTS: CAD was present in 35.1% of population A and in 1.4% of population B. In population A total cholesterol and LDL were above the expected, in all age groups. About 70% of these patients had cholesterol greater than 200 mg% and LDL greater than 130 mg%, which are considered desirable levels; 28% of women and 44% of men had HDL less than 35 mg%. Conversely, in population B total cholesterol and LDL were slightly above normal only in patients greater than 45 years old. In addition, about 65% of population had cholesterol less than 200 mg% and LDL less than 130 mg%; even so, 28% of women and 48% of men had HDL less than 35 mg%. In population A, there were no significant differences between the percentages of patients with and without CAD, over a wide range of cholesterol values. Similarly, levels of LDL, HDL and triglycerides as well as the incidence of hypertension, smoking and diabetes did not differ between patients with and without CAD. CONCLUSION: There is a high incidence of dyslipidemia in these brazilian populations, especially among patients from private office. Further, the isolated measurement of lipid fractions does not discriminate between patients with and without DAC, suggesting that other factors are involved in the genesis of the disease.

[Differences between men and women in fatal cases of myocardial infarction: study of 200 necropsies]. / Diferenças entre homens e mulheres em casos fatais de infarto do miocárdio. Estudo de 200 necrópsias.

PURPOSE: To compare morphological characteristics from myocardial infarction (IM) in men and women in 200 consecutive necropsies. MATERIAL AND METHODS: Necropsy heart findings from 62 female cases compared with those from 138 male cases, from patients who died from transmural myocardial infarction. Age ranged from 21 to 82 (mean 60) years. RESULTS: Concerning the coronary arteries, the number of 3 major (right, left anterior descending and left circumflex) epicardial coronary arteries narrowed at some point greater than 70% in cross-sectional area by atherosclerotic plaque was not significantly different; on the other hand, there were more severe lesions in the left main coronary artery in men (10.33%) than in women (1.64%) (p = 0.050). 33.33% of men and 43.55% of women had only recent myocardial infarction (1 month or less); 33.33% of men and 14.52% of women had only old myocardial infarction (more than 1 month); 33.33% of men and 41.94% of women had both recent and old myocardial infarction. 12.90% of women and 2.17% of men showed rupture of the left ventricle (p = 0.0220). 15.22% of men and 6.45% of women had left ventricular aneurysms (p = 0.830). CONCLUSION: There are more deaths during the acute phase of MI, in the first infarction and from rupture of the left ventricle in female patients; in men, there are more deaths occurring in chronic phases of the disease and with previous myocardial infarction; and more severe narrowing from the left main coronary artery.

[Infective endocarditis: analysis of 300 episodes]. / Endocardite infecciosa: análise de 300 episódios.

PURPOSE: Study of clinical features and etiologic agents, treatment and mortality of patients with infective endocarditis (IE). PATIENTS AND METHODS: 300 episodes of IE occurring in 288 patients, ages ranged between 0.2 and 78 (mean 30.76) years; 185 (62%) episodes occurred in males. RESULTS: a) etiologic agents: viridans group streptococci in 93 (31%) episodes, enterococci en 21 (7%), group D-non enterococci in 19 (6%) (13 S. bovis), other streptococci in 14 (5%), Staphylococcus aureus in 59 (20%), Staphylococcus epidermidis in 14 (5%), gram-negative bacteria in 16 (5%), gram-positive bacteria other than streptococci and staphylococci in 8 (3%), fungi in 4 (1%). The etiologic agents were not identified in 52 (17%) episodes; b) underlying cardiac diseases: valvular heart disease in 119 (40%) episodes, congenital heart disease in 37 (12%), prosthetic heart valves in 69 (23%), other heart diseases in 6 (2%). There was no evidence of previous heart disease in 69 (23%); c) treatment: surgical treatment was undertaken in 102 (34%) episodes. The frequency of surgical treatment in relation to the etiologic agents ranged between 1% (non-group D streptococci) and 62% (negative blood cultures). The frequency of operation in relation to underlying heart disease ranged between 17% (other heart diseases), 19% (congenital heart disease) and 54% (prosthetic heart valve); d) mortality: 78 (26%) patients died, 56 (28%) of the 198 submitted to medical treatment and 22 (21%) of the 102 submitted also to surgical treatment. The mortality in the different groups of etiologic agents ranged between 5% (non-group D streptococci) and 62% (gram-positive bacteria other than streptococci and staphylococci); in relation to the underlying heart disease, the mortality was 16% in patients with other heart disease, 19% in valvular heart disease patients, 21% in patients with congenital heart disease, 23% in patients without known heart disease and 43% in patients with prosthetic heart valves. CONCLUSION: The mortality associated with IE remains still high in spite of modern treatment; the mortality is different in relation to the different etiologic agents and in relation to the cardiac status before the IE.

A simple local database for audit and epidemiologic studies.

The Authors, after having outlined the importance of clinical audit in order to improve the perinatal care provided and reduce management-dishomogeneity between obstetrical staff members, present a simple off-line system of computerized perinatal data collection that has proved to be the useful for audit applications and statistical epidemiological evaluations.