In vitro exposure of porcine spermatozoa to methylparaben, and propylparaben, alone or in combination adversely affects sperm quality.

Parabens (PBs) are widely used in the cosmetic, pharmaceutical, and food industries as preservatives of products. Because of its great use, humans and other organisms are highly exposed daily. However, little is known about the effect of PBs on male infertility. Therefore, the aim of the present study was to evaluate the effect of methylparaben (MePB) and propylparaben (PrPB), alone or in combination, on the physiological characteristics of pig in vitro exposed sperm to different concentrations (0, 200, 500, and 700 µM) for viability, motility, and acrosome integrity evaluation and (0, 200, 500, 700, 1000, and 2000 µM) for DNA fragmentation index evaluation, after 4 h of exposure. The results showed that sperm viability decreased after exposure to MePB from the concentration of 500 µM. In the PrPB and mixture groups, viability decreased at all concentrations except for the control. The decrease in viability of sperm exposed to PrPB was greater than that of the mixture and MePB groups. Sperm motility decreased in all the experimental groups exposed to PBs, at all concentrations, except for the control group. Acrosome integrity was not decreased in the MePB group; however, in the PrPB group, it decreased at a concentration of 200 µM and in the mixture at 500 µM. All groups exhibited DNA damage at different concentrations, except for the control group. Additionally, the effect of PBs on sperm quality was concentration-dependent. The results demonstrated that MePB and PrPB alone or in combination can have adverse effects on sperm quality parameters. MePB had lower toxicity than did both PrPB and the mixture. The mixture did not have an additive effect on any of the parameters evaluated. This could partially explain the link between PB exposure and infertility.

Recomendaciones Rama de Dermatología Pediátrica, Sociedad Chilena de Pediatría. Pandemia COVID-19 / Recommendations Pediatric Dermatology Branch, Chilean Society of Pediatrics. COVID-19 pandemic

Resumen: La actual pandemia por Covid-19 (SARS-CoV-2) corresponde a una zoonosis viral altamente con tagiosa que ha requerido extremar las medidas de protección personal con el fin de disminuir la transmisión del virus, tanto en ambientes hospitalarios como fuera de ellos, siendo necesaria la adopción de estrictos métodos de aislamiento tanto de contacto como aerosoles. Esto ha reque rido la adopción de múltiples equipos de protección personal, dentro de los que se encuentran la protección ocular, mascarillas, escudo de protección facial, gorros, guantes, etcétera. Lo anterior ha generado un aumento en el daño de la barrera cutánea y, por lo tanto, la aparición de diversas dermatosis dentro de las que se encuentran dermatitis de contacto irritativa o alérgica, reaccio nes acneiformes, agravamiento de dermatosis previas, entre otras, cobrando así vital importancia el cuidado y restablecimiento de la barrera cutánea con medidas esenciales como aplicación de productos humectantes o emolientes y el correcto uso de los equipos en mención. No obstante, no solo se generan dermatosis derivadas del uso de equipos de protección personal, sino que tam bién, dentro del amplio espectro de manifestaciones dermatológicas que puede generar la enfer medad por Covid-19 propiamente tal, incluyendo compromiso cutáneo, piloso (efluvio telógeno) o ungueal (onicomadesis). Por otro lado pero no motivo de este artículo, el compromiso cutáneo puede corresponder a la primera expresión clínica de la enfermedad o ser un predictor de su evolu ción. Dentro de lo anterior encontramos la urticaria aguda, exantema maculo-papular, exantema varicela-like, erupción petequial, perniosis-like y lívedo reticularis como las principales formas de afección cutánea hasta el momento.

Abstract: The current Covid-19 pandemic (SARS-CoV-2) corresponds to a highly contagious viral zoonosis that has required to extreme measures in order to decrease the transmission of the virus in hospi tal settings and outside of them, requiring adoption of strict isolation methods, both contact and aerosols. This has required the adoption of multiple personal protective equipment, including eye protection, masks, face shield, medical caps, gloves, etc. The aforementioned has generated an in crease in the damage of the skin barrier, and therefore, the appearance of various dermatoses, among which are irritative o alergic contact dermatitis, acneiform reactions, aggravation of previous der matoses, and others, thus becoming vital protection and restoration of the skin barrier with mea sures such as the application of moisturizing or emollient products and the correct use of personal protection equipment. However, not only dermatoses are generated derived from the use of perso nal protection equipment, but also, within the wide spectrum of dermatological manifestations that Covid-19 disease itself can generate, including cutaneous, hairy involvement (telogen effluvium) or nail (onychomadesis). Cutaneous involvement may correspond to the first clinical expression of the disease or be a predictor of its evolution. Among the above we find acute urticaria, maculo-papular rash, chickenpox-like rash, petechial rash, perniosis-like, and livedo reticularis as the main forms of skin condition to date.

A master dynamic flow diagram for the shear thickening transition in micellar solutions.

The shear thickening behavior of dilute micellar solutions of hexadecyltrimethylammonium-type surfactants with different counterions (tosylate, 3- and 4-fluorobenzoate, vinylbenzoate and salicylate) and of n-alkyltetradecylammonium bromide (CnTAB), with n = 14, 16 and 18, is examined here. These solutions undergo a shear thickening transition due to the formation of shear-induced structures (SISs) in the shear range studied. Here we report a relationship between the shear thickening intensity and the differences in the hydrophobicity of counterions according to the Hofmeister-like anion series, which leads to a master flow diagram. This master flow diagram is produced by plotting a normalized shear thickening intensity (Iη - 1)/(Imax - 1) versus CD/CD,max, where Iη is the shear-thickening intensity, defined as the largest viscosity obtained in the shear-thickening transition (STT) at a given surfactant concentration CD divided by the Newtonian viscosity η0, and Imax is the largest intensity value obtained in the STT at a surfactant concentration CD,max. The master flow diagram is built using several cetyltrimethylammonium-type surfactants with different counterions, according to a Hofmeister-like series, and by n-alkyltetradecylammonium bromide surfactants with different alkyl chain lengths.

Aggregation and adsorption behavior of low concentration aqueous solutions of hexadecyltrimethylammonium ortho, meta, and parafluorobenzoate.

The aggregation properties of 2-, 3-, and 4-fluorobenzoic acids (2FBA, 3FBA, and 4FBA, respectively) and their salts with hexadecyltrimethylammonium cations (HTA2FB, HTA3FB, and HTA4FB) in water were studied with a battery of techniques. Their activity at the air/solution interface has been also studied. The position of the fluorine atom in the acid affected the solubility, adsorption, and aggregation in the pure acids solutions. The 4FBA is less water soluble, more hydrophobic, and has the lower critical aggregation concentration of the three isomers. The behavior of the HTA2FB compound in aqueous solution is different from that of HTA3FB and HTA4FB. The critical micelle concentration, critical concentration for sphere-to-rod-like micelle transition, and Krafft point of HTA3FB and HTA4FB are lower than those of the other surfactant but their surface activities are higher. The differences between the HTA2FB and the other two surfactants have been explained on the basis of the regular solution theory of mixed micelles and in light of the analysis of the hydration shell of the acids through molecular dynamic simulations. The results of the present work suggest that the different behaviors are due to a combination of different dehydration tendencies and the steric possibility of inclusion of the counterions in the micelle palisade layer. The formation of rod-like micelles by HTA2FB, while the tetradecyltrimethylammonium 2-fluorobenzoate only forms spherical aggregates, is explained on the basis of the packing parameter. The mentioned factors are complementary to others presented in literature. These conditions may be used in the rational design of micelles by means of molecular dynamics simulations, reducing the trial-and-error approach used to date.

Effects of electrolyte concentration and counterion valence on the microstructural flow regimes in dilute cetyltrimethylammonium tosylate micellar solutions.

The shear thickening behavior and the transition to shear thinning are examined in dilute cetyltrimethylammonium tosylate (CTAT) micellar solutions as a function of surfactant concentration and ionic strength using electrolytes with different counterion valence. Newtonian behavior at low shear rates, followed by shear thickening and shear thinning at higher shear rates, are observed at low and intermediate surfactant and electrolyte concentrations. Shear thickening diminishes with increasing surfactant concentration and ionic strength. At higher surfactant or electrolyte concentration, only a Newtonian region followed by shear thinning is detected. A generalized flow diagram indicates two controlling regimes: one in which electrostatic screening dominates and induces micellar growth, and another, at higher electrolyte and surfactant concentrations, where chemical equilibrium among electrolyte and surfactant counterions controls the rheological behavior by modifying micellar breaking and reforming. Analysis of the shear thickening behavior reveals that not only a critical shear rate is required for shear thickening, but also a critical deformation, which appears to be unique for all systems examined, within experimental error. Moreover, a superposition of the critical shear rate for shear thickening with surfactant and electrolyte concentration is reported.

Phase and rheological behavior of the hexadecyl(trimethyl)azanium; 2-hydroxybenzoate/water system.

The phase and rheological behavior of hexadecyl(trimethyl)azanium; 2-hydroxybenzoate (CTAS), and water as a function of surfactant concentration and temperature are investigated here. The critical micellization concentration (cmc(1)) and the concentration at which the structure of aggregates changes (cmc(2)) as well as the Krafft temperature (T(K)) are reported. A large micellar solution region exhibiting high viscosity, as well as hexagonal- and lamellar-phase regions were identified. In the dilute region, below the overlapping entanglement concentration (C*), the micellar solutions exhibit shear thickening. Above C*, wormlike micelles form and the solutions show strong viscoelasticity with Maxwell behavior in the linear regime and shear banding flow in the non-linear regime. The linear viscoelastic regime was analyzed with the Granek-Cates model, showing that the relaxation is controlled by the kinetics of reformation-and-scission of the micelles. The steady response in the non-linear regime is compared with the predictions of the Bautista-Manero-Puig (BMP) and the Giesekus models.

Rheology of the Pluronic P103/water system in a semidilute regime: evidence of nonequilibrium critical behavior.

The linear and nonlinear rheological behaviors of semidilute aqueous solutions of the amphiphile triblock polymer Pluronics P103 in water are reported here. For C(surf) < or = 20 wt%, micelles are spherical at temperatures lower than ca. 27 degrees C and grow with increasing temperature to form long polymer-like micelles. These polymer-like micelles exhibit strong viscoelasticity and a shear-banding region that shrinks as the cloud point is approached. Master time-temperature-concentration curves were obtained for the dynamic moduli using traditional shifting factors. In the nonlinear regime, P103 polymer-like micellar solutions follow the master dynamic phase diagram proposed by Berret and colleagues, in which the flow curves overlap in the low-shear-rate homogeneous flow region. Within the nonhomogeneous flow region (confirmed by flow birefringence and small-angle light-scattering measurements), oscillations and overshoots are detected at the inception of shear flow, and two main relaxation mechanisms are apparent after cessation of steady shear flow. Evidence for nonequilibrium critical behavior is presented, in which the order parameter is the difference of critical shear rates that limit the span of the plateau stress. Most of the steady-state and transient features of the nonlinear rheology of the P103 polymer-like micelles are reproduced with the Bautista-Manero-Puig (BMP) model, including the predictions of nonequilibrium critical behavior under flow.

Phase behavior of the Pluronic P103/water system in the dilute and semi-dilute regimes.

The detailed temperature-composition phase diagram of the P103/water system in the dilute and semidilute regions is reported here using density and ultrasound velocity measurements, differential scanning calorimetry (DSC), rheometry and dynamic (DLS) and static light scattering (SLS). These techniques allow a precise determination of the critical micellar temperature (CMT), the sphere-to-rod micellar transition temperature (GMT) and the cloud point temperature (CPT) as a function of concentration. DLS and SLS measurements were employed to gain information on unimers and aggregate sizes and on the transition from spherical-to-rod micelles.

Phase and rheological behavior of the polymerizable surfactant CTAVB and water.

The phase and rheological behaviors of the polymerizable surfactant, cetyltrimethylammonium benzoate (CTAVB), and water as a function of surfactant concentration and temperature are investigated here. The critical micelle concentration (cmc) and the (cmc(2)), as well as the Krafft temperature (T(K)), are reported. A large highly viscous micellar solution region and hexagonal- and lamellar-phase regions were identified. The micellar solutions exhibit shear thickening in the dilute regime, below the overlapping or entanglement concentration. At higher concentrations, wormlike micelles form and the solutions show strong viscoelasticity and Maxwell behavior in the linear regime and shear banding flow in the nonlinear regime. The linear viscoelastic regime is analyzed with the Granek-Cates model, showing that the relaxation is controlled by the kinetics of reformation and scission of the micelles. The steady and unsteady responses in the nonlinear regime are compared with the predictions of the Bautista-Manero-Puig (BMP) model. Model predictions follow the experimental data closely.

Crossing the border for health care.

A survey was administered to adults attending a health fair in south Los Angeles County, approximately 140 miles from the U.S.-Mexico border. The survey revealed that 14 percent of respondents had crossed the border to seek medical care during the past year. Nearly 80 percent of respondents crossing the border for medical care were uninsured, while 70 percent reported the low cost of medical care obtained across the border as being the most common reason for seeking care there. Twenty-eight percent of respondents reported purchasing medication in Mexico, with antibiotics and pain medication being reported in highest frequency. Ninety percent of these respondents were uninsured. This study shows that the high cost of health care and lack of insurance compels the poor and uninsured to seek low-cost health care and medication in Mexico to meet their most urgent health care needs, despite the burden of cost and travel.

[Diagnostic performance of immunologic tests in amebic liver abscess using receiver operating characteristic curves]. / Rendimiento diagnóstico de las pruebas inmunológicas en absceso hepático amibiano a través de curvas de características operantes del receptor.

Objectives. 1) To identify the tests of immunological diagnosis with a high diagnostic efficiency in amebic liver abscess. 2) To determine the ideal cutoff point for such tests. 3) To identify the influence degree of the antigen used over the test efficiency. Design. Comparative survey. Study units. Analysis of 24 articles identified in the medical literature about tests of immunological diagnosis in amebic liver abscess. Measurements. Starting from the articles, operating characteristics curves (ROC) were established derived from the test application to patients with amebic liver abscess. Results. A great variability in the diagnostic efficiency was identified between the various tests, even when the analysis was focused on the investigations of a specific test. It was not possible to conclude which test had a major degree of efficiency due to such variability. The cutoff level considered as relevant was higher than the one traditionally used for indirect hemagglutination and it had concordance with the one presently accepted for the fluorescence antibodies test. By maintaining steady the spectrum of the study patients and the type of test, variability among the tests persisted. This was due to the use of different antigens. Conclusions. A great variation in the diagnostic efficiency of the analyzed tests was identified. The variation source was the type of test, the antigen used and probably the illness spectrum.

[Evaluation of immunologic diagnostic tests in amebiasis: diagnosis or bias? A critical review of the literature]. / Evaluación de las pruebas de diagnóstico inmunológico en amibiasis: diagnóstico ó sesgo?

OBJECTIVE: 1. To describe the frequency of adherence to methodologic criteria proposed for assessment of diagnostic tests. 2. To identify potential bias. 3. To construct Receiver Operating Characteristic (ROC) curves based on data published on the assessed papers. DESIGN: Descriptive cross-sectional survey. STUDY MATERIAL: All papers listed under diagnosis and immunological headings of amebiasis in the Index Medicus from 1970 to 1988. STUDY UNITS: 80 papers. MEASUREMENT: a: Adherence to methodologic criteria proposed for assessment of diagnostic test. b: presence of potential bias. MAIN RESULTS: The adherence to methodologic criteria varied 1 to 55% of the papers. The comparison with a "gold standard" occurred in 40% the independent "blind" assessment occurred in 6% the setting for the study was described 1%. The study of an appropriate spectrum of disease was done in 11%. We were able to construct ROC curves with data from 37 papers and differences were observed among studies evaluating the same test. A high proportion of papers had potential bias. CONCLUSIONS: The adherence to methodologic standards is poor in the papers analyzed in this series. Consequently the frequency of potential bias was high.

Agenesia de traquea. Presentacion de un caso y revision de la literatura. / Agenesis of the trachea. Report of a case and review of the literature

La agenesia de traquea es una anormalidad congenita muy rara; al momento actual solo se han referido 34 casos en la literatura medica. Es frecuente la asociacion con otras malformaciones congenitas. En este trabajo se describe el caso de un paciente con agenesia traqueal, asociada con defecto septal ventricular