Impacto en la salud mental de los profesionales sanitarios que prestan asistencia a pacientes durante el brote del Covid-19 / Impact on the mental wellbeing of health professionals who provide care to patients during the Covid-19 outbreak

Las principales repercusiones de pandemias anteriores en el personal sanitario son los problemas de salud mental. Sin embargo, existe poca evidencia disponible relacionada a cómo el COVID-19 está afectando la salud mental en el personal sanitario. El objetivo de esta revisión de literatura fue analizar el impacto que ha tenido la pandemia en la salud mental de los profesionales de salud. Se realizó una revisión de literatura narrativa utilizando las bases de datos de Proquest y PubMed, 11 artículos fueron seleccionados de acuerdo al cumplimiento de los criterios definidos. Los trastornos mentales más frecuentes en el personal sanitario que trabaja directamente en la atención de pacientes Covid-19 son: el estrés, depresión, ansiedad y la angustia, insomnio, hiperactividad y baja calidad de vida, afectan también al personal sanitario. Estos trastornos mentales son provocados por diversos factores como el exceso de carga laboral, miedo a infectarse e infectar a sus familias, falta de medios de protección personal y temor de ser discriminados entre otros. La pandemia del COVID-19 afecta negativamente la salud mental de los profesionales de salud que trabajan directamente en la atención de pacientes, así también como la calidad de vida, por lo que es fundamental tomar acciones para proteger a los funcionarios de salud.

The main repercussions of previous pandemics on health workers are mental health problems. However, there is little evidence available related to how COVID-19 is affecting mental wellbeing in healthcare personnel. This literature review's objective was to analyze the impact that the pandemic has had on the mental wellbeing of health professionals. A narrative literature review was carried out using the Proquest and PubMed databases; 11 articles were selected according to the defined criteria' fulfillment. The most frequent mental disorders in health personnel who work directly in the care of Covid-19 patients are: stress, depression, anxiety and anguish, insomnia, hyperactivity, and low quality of life, which also affect health personnel. These mental disorders are caused by various factors such as excessive workload, fear of becoming infected and infecting their families, lack of means of personal protection, and fear of being discriminated against, among others. The COVID-19 pandemic negatively affects the mental wellbeing of health professionals who work directly in patient care and the quality of life, so it is essential to take action to protect health workers.

Enhanced Data Covariance Estimation Using Weighted Combination of Multiple Gaussian Kernels for Improved M/EEG Source Localization.

In the recent past, estimating brain activity with magneto/electroencephalography (M/EEG) has been increasingly employed as a noninvasive technique for understanding the brain functions and neural dynamics. However, one of the main open problems when dealing with M/EEG data is its non-Gaussian and nonstationary structure. In this paper, we introduce a methodology for enhancing the data covariance estimation using a weighted combination of multiple Gaussian kernels, termed WM-MK, that relies on the Kullback-Leibler divergence for associating each kernel weight to its relevance. From the obtained results of validation on nonstationary and non-Gaussian brain activity (simulated and real-world EEG data), WM-MK proves that the accuracy of the source estimation raises by more effectively exploiting the measured nonlinear structures with high time and space complexity.

Effect of effort-reward imbalance and burnout on infection control among Ecuadorian nurses.

BACKGROUND: Nurses are frequently exposed to transmissible infections, yet adherence to infection control measures is suboptimal. There has been inadequate research into how the psychosocial work environment affects compliance with infection control measures, especially in low- and middle-income countries. AIM: To examine the association between effort-reward imbalance, burnout and adherence to infection control measures among nurses in Ecuador. INTRODUCTION: A cross-sectional study linking psychosocial work environment indicators to infection control adherence. METHODS: The study was conducted among 333 nurses in four Ecuadorian hospitals. Self-administered questionnaires assessed demographic variables, perceived infection risk, effort-reward imbalance, burnout and infection control adherence. RESULTS: Increased effort-reward imbalance was found to be a unique incremental predictor of exposure to burnout, and burnout was a negative unique incremental predictor of nurses' self-reported adherence with infection control measures. DISCUSSION: Results suggest an effort-reward imbalance-burnout continuum, which, at higher levels, contributes to reduce adherence to infection control. The Ecuadorean government has made large efforts to improve universal access to health care, yet this study suggests that workplace demands on nurses remain problematic. CONCLUSION: This study highlights the contribution of effort-reward-imbalance-burnout continuum to the chain of infection by decreased adherence to infection control of nurses. IMPLICATIONS FOR NURSING POLICY: Health authorities should closely monitor the effect of new policies on psychosocial work environment, especially when expanding services and increasing public accessibility with limited resources. Additionally, organizational and psychosocial interventions targeting effort-reward imbalance and burnout in nurses should be considered part of a complete infection prevention and control strategy. Further study is warranted to identify interventions that best ameliorate effort-reward imbalance and burnout in low- and middle-income settings.

Freshwater fish faunas, habitats and conservation challenges in the Caribbean river basins of north-western South America.

The remarkable fish diversity in the Caribbean rivers of north-western South America evolved under the influences of the dramatic environmental changes of neogene northern South America, including the Quechua Orogeny and Pleistocene climate oscillations. Although this region is not the richest in South America, endemism is very high. Fish assemblage structure is unique to each of the four aquatic systems identified (rivers, streams, floodplain lakes and reservoirs) and community dynamics are highly synchronized with the mono-modal or bi-modal flooding pulse of the rainy seasons. The highly seasonal multispecies fishery is based on migratory species. Freshwater fish conservation is a challenge for Colombian environmental institutions because the Caribbean trans-Andean basins are the focus of the economic development of Colombian society, so management measures must be directed to protect aquatic habitat and their connectivity. These two management strategies are the only way for helping fish species conservation and sustainable fisheries.

Participation of inositol trisphosphate and ryanodine receptors in Bufo arenarum oocyte activation.

Calcium is considered the most important second messenger at fertilization. Transient release from intracellular stores is modulated through both agonist-gated channels, IP3Rs and RyRs, which can be found individually or together depending on the oocyte species. Using the four commonly used compounds (thimerosal, caffeine, heparin and ruthenium red), we investigated the existence and interdependence of both IP3Rs and RyRs in mature Bufo arenarum oocytes. We found that caffeine, a well known specific RyRs agonist, was able to trigger oocyte activation in a dose-dependent manner. Microinjection of 10 mM caffeine showed 100% of oocytes exhibiting characteristic morphological criteria of egg activation. Ruthenium red, the specific RyR blocker, was able to inhibit oocyte activation induced either by sperm or caffeine. Our present findings provide the first reported evidence of the existence of RyR in frogs. We further explored the relationship between IP3Rs and RyRs in B. arenarum oocytes by exposing them to the agonists of one class after injecting a blocker of the other class of receptor. We found that thimerosal overcame the inhibitory effect of RyR on oocyte activation, indicating that IP3Rs function as independent receptors. In contrast, previous injection of heparin delayed caffeine-induced calcium release, revealing a relative dependence of RyRs on functional IP3Rs, probably through a CICR mechanism. Both receptors play a role in Ca²+ release mechanisms although their relative contribution to the activation process is unclear.

Participation of MAPK, PKA and PP2A in the regulation of MPF activity in Bufo arenarum oocytes.

The objectives of the present paper were to study the involvement and possible interactions of both cAMP-PKA and protein phosphatases in Bufo arenarum oocyte maturation and to determine if these pathways are independent or not of the MAP kinase (MAPK) cascade. Our results indicated that the inhibition of PKA by treatment with H-89, an inhibitor of the catalytic subunit of PKA, was capable of inducing GVBD in a dose-dependent manner by a pathway in which Cdc25 phosphatase but not the MAPK cascade is involved. The injection of 50 nl of H-89 10 µM produced GVBD percentages similar to those obtained with treatment with progesterone. In addition, the assays with okadaic acid (OA), a PP2A inhibitor, significantly enhanced the percentage of oocytes that resumed meiosis by a signal transducing pathway in which the activation of the MEK-MAPK pathway is necessary, but in which Cdc25 phosphatase was not involved. Treatment with H-89, was able to overcome the inhibitory effect of PKA on GVBD; however, the inhibition of Cdc25 activity with NaVO3 was able to overcome the induction of GVBD by H-89. Although the connections between PKA and other signalling molecules that regulate oocytes maturation are still unclear, our results suggest that phosphatase Cdc25 may be the direct substrate of PKA. In Xenopus oocytes it was proposed that PP2A, a major Ser/Thr phosphatase present, is a negative regulator of Cdc2 activation. However, in Bufo arenarum oocytes, inhibition of Cdc25 with NaVO3 did not inhibit OA-induced maturation, suggesting that the target of PP2A was not the Cdc25 phosphatase. MAPK activation has been reported to be essential in Xenopus oocytes GVBD. In B. arenarum oocytes we demonstrated that the inhibition of MAPK by PD 98059 prevented the activation of MPF induced by OA, suggesting that the activation of the MAPK cascade produced an inhibition of Myt1 and, in consequence, the activation of MPF without participation of the Cdc25 phosphatase. Our results suggest that in incompetent oocytes of B. arenarum two signal transduction pathways may be involved in the control of MPF activation: (1) the inhibition of phosphatase 2A that through the MEK-MAPK pathway regulates the activity of the Myt1; and (2) the inhibition of AMPc-PKA, which affects the activity of the Cdc25 phosphatase.

Substrate vibrations in the scorpion Centruroides margaritatus (Scorpiones: Buthidae) during courtship / Vibraciones del sustrato en el escorpión Centruroides margaritatus (Scorpiones: Buthidae) durante el cortejo

Mating behavior in Centruroides margaritatus, as in other scorpion species, includes a series of rapid rocking or shaking movements of the male ("juddering"). It has been suggested that substrate vibrations are generated by juddering and that females respond to them by approaching the male, but its functional significance remains little studied. For the first time, substrate vibrations produced by males during courtship in Centruroides margaritatus are documented. The male started juddering after his first physical contact with the female and only one type of male vibratory signal was registered. The signal is produced during a series of rapid shaking of the male’s body from front to rear and consists of multiple short pulses. Each pulse is called a judder and several judders "a series". The average duration of each judder was 0.018±0.009s (n=50) with an interval of 0.028±0.013s (n=50); the average duration of each series of judders was 4.2±3.5s with an interval between series of 3.5±6.3s and a rate of 0.21±0.17 series per second. The females responded in 72% of the time to the males juddering. Rev. Biol. Trop. 57 (Suppl. 1): 267-274. Epub 2009 November 30.

El comportamiento de apareamiento en Centruroides margaritatus como en otras especies del escorpiones, incluye una serie de oscilaciones rápidas hacia adelante y hacia atrás del cuerpo del macho (juddering). Se ha especulado que tales oscilaciones generan vibraciones en el substrato y las hembras pueden responder a ellas aproximándose al macho, pero su significado funcional sigue siendo poco estudiado. Por primera vez, las vibraciones del substrato producidas por los machos durante el comportamiento de cortejo de Centruroides margaritatus son documentadas. El macho comenzó las vibraciones después de su primer contacto físico con la hembra y sólo se registró un tipo de señal vibratoria. La señal se produce durante una serie de rápidas sacudidas del cuerpo del macho de adelante hacia atrás y se compone de múltiples pulsos cortos. La duración media de cada pulso fue 0.018±0.009s (n = 50) con un intervalo de 0.028±0.013s (n=50); la duración media de cada serie de pulsos fue de 4.2±3.5s, con un intervalo entre las series de 3.5±6.3s y una tasa de 0.21±0.17 serie por segundo. Las hembras respondieron en un 72% del tiempo a las sacudidas de los machos. Se discute acerca de su posible función como señal.

Activation of amphibian oocytes by sperm extracts.

In the fertilization of most animals, egg activation is accompanied by an increase in cytoplasmatic Ca2+; however, the mechanism through which the fertilizing sperm induce this phenomenon is still controversial. An increase in intracellular free Ca2+ is required to trigger egg activation events, a process that includes cortical granule exocytosis, resumption and completion of meiosis and DNA replication, and culminates in the first mitotic cleavage. In this work, we investigated the effect of microinjection and incubation of different fractions of homologous sperm extract on the activation of Bufo arenarum oocytes matured in vitro. Two heat treatment-sensitive fractions obtained by chromatography were able to induce oocyte activation. The sperm fraction, which contained a 24 kDa protein, induced 90% activation when it was microinjected into the oocytes. Whilst the sperm fraction, which contained a 36 kDa protein, was able to induce about 70% activation only when it was applied on the oocyte surface.

Involvement of GABAA receptor in Bufo arenarum oocyte maturation.

Amphibian oocytes meiotic arrest is released under the stimulus of progesterone; this hormone interacts with the oocyte surface and starts a cascade of events leading to the activation of a cytoplasmic maturation promoting factor (MPF) that induces germinal vesicle breakdown (GVBD), chromosome condensation and extrusion of the first polar body. The aim of this work was to determine whether the activation of a GABAA receptor is able to induce GVBD in fully grown denuded oocytes of Bufo arenarum and to analyse its possible participation in progesterone-induced maturation. We also evaluated the role of purines and phospholipids in the maturation process induced by a GABAA receptor agonist such as muscimol. Our results indicated that the activation of the GABAA receptor by muscimol induces maturation in a dose- and time-dependent manner and that this activation is a genuine maturation that enables oocytes to form pronuclei. Assays with a receptor antagonist, picrotoxine, showed that the maturation induced by muscimol was inhibited. Treatment with picrotoxine, however, shows that the participation of GABAA receptor in progesterone-induced maturation is not significant. In addition, our results indicate that high intracellular levels of purines obtained by the use of db-AMPc and theophylline or the inhibition of the phosphatidylinositol 4,5-bisphosphate (PIP2 hydrolysis by neomycin and PIP2 turn over by LiCl, respectively, inhibited the maturation induced by muscimol. Treatment with H-7 indicated, however, that PKC activation is not necessary for GVBD induced by the GABAA receptor agonist. Results suggest that the transduction pathway used by the GABAA receptor to induce maturation is different from those used by progesterone.

Spontaneous and LH-induced maturation in Bufo arenarum oocytes: importance of gap junctions.

It has been demonstrated in Bufo arenarum that fully grown oocytes are capable of meiotic resumption in the absence of a hormonal stimulus if they are deprived of their follicular envelopes. This event, called spontaneous maturation, only takes place in oocytes collected during the reproductive period, which have a metabolically mature cytoplasm. In Bufo arenarum, progesterone acts on the oocyte surface and causes modifications in the activities of important enzymes, such as a decrease in the activity of adenylate cyclase (AC) and the activation of phospholipase C (PLC). PLC activation leads to the formation of diacylglycerol (DAG) and inositol triphosphate (IP(3)), second messengers that activate protein kinase C (PKC) and cause an increase in intracellular Ca(2+). Recent data obtained from Bufo arenarum show that progesterone-induced maturation causes significant modifications in the level and composition of neutral lipids and phospholipids of whole fully grown ovarian oocytes and of enriched fractions in the plasma membrane. In amphibians, the luteinizing hormone (LH) is responsible for meiosis resumption through the induction of progesterone production by follicular cells. The aim of this work was to study the importance of gap junctions in the spontaneous and LH-induced maturation in Bufo arenarum oocytes. During the reproductive period, Bufo arenarum oocytes are capable of undergoing spontaneous maturation in a similar way to mammalian oocytes while, during the non-reproductive period, they exhibit the behaviour that is characteristic of amphibian oocytes, requiring progesterone stimulation for meiotic resumption (incapable oocytes). This different ability to mature spontaneously is coincident with differences in the amount and composition of the phospholipids in the oocyte membranes. Capable oocytes exhibit in their membranes higher quantities of phospholipids than incapable oocytes, especially of PC and PI, which are precursors of second messengers such as DAG and IP(3). The uncoupling of the gap junctions with 1-octanol or halothane fails to induce maturation in follicles from the non-reproductive period, whose oocytes are incapable of maturing spontaneously. However, if the treatment is performed during the reproductive period, with oocytes capable of undergoing spontaneous maturation, meiosis resumption occurs in high percentages, similar to those obtained by manual defolliculation. Interestingly, results show that LH is capable of inducing GVBD in both incapable oocytes and in oocytes capable of maturing spontaneously as long as follicle cells are present, which would imply the need for a communication pathway between the oocyte and the follicle cells. This possibility was analysed by combining LH treatment with uncoupling agents such as 1-octanol or halothane. Results show that maturation induction with LH requires a cell-cell coupling, as the uncoupling of the gap junctions decreases GVBD percentages. Experiments with LH in the presence of heparin, BAPTA/AM and theophylline suggest that the hormone could induce GVBD by means of the passage of IP(3) or Ca(2+) through the gap junctions, which would increase the Ca(2+) level in the oocyte cytoplasm and activate phosphodiesterase (PDE), thus contributing to the decrease in cAMP levels and allowing meiosis resumption.

Behaviour of the vitelline envelope in Bufo arenarum oocytes matured in vitro in blockade to polyspermy.

During activation of amphibian eggs, cortical granule exocytosis causes elaborate ultrastructural changes in the vitelline envelope. These changes involve modifications in the structure of the vitelline envelope and formation of a fertilization envelope (FE) that can no longer be penetrated by sperm. In Bufo arenarum, as the egg traverses the oviduct, the vitelline envelope is altered by a trypsin-like protease secreted by the oviduct, which induces an increased susceptibility of the vitelline envelope to sperm lysins. Full-grown oocytes of B. arenarum, matured in vitro by progesterone, are polyspermic, although cortical granule exocytosis seems to occur within a normal chronological sequence. These oocytes can be fertilized with or without trypsin treatment, suggesting that the vitelline envelope is totally sperm-permeable. Vitelline envelopes without trypsin treatment cannot retain either gp90 or gp96. This suggests that these glycoproteins are involved in the block to polyspermy and that trypsin treatment of matured in vitro oocytes before insemination is necessary to enable vitelline envelopes to block polyspermy. The loss of the binding capacity in vitelline envelopes isolated from B. arenarum oocytes matured in vitro with trypsin treatment and activated by electric shock suggests that previous trypsin treatment is a necessary step for sperm block to occur. When in vitro matured oocytes were incubated with the product of cortical granules obtained from in vitro matured oocytes (vCGP), vitelline envelopes with trypsin treatment were able to block sperm entry. These oocytes exhibited the characteristic signs of activation. These results support the idea that B. arenarum oocytes can be activated by external stimuli and suggest the presence of unknown oocyte surface receptors linked to the activation machinery in response to fertilization. Electrophoretic profiles obtained by SDS-PAGE of solubilized vitelline envelopes from oocytes matured in vitro revealed the conversion of gp40 (in vitro matured oocytes, without trypsin treatment) to gp38 (ascribable to trypsin activity or cortical granule product activity, CGP) and the conversion of gp70 to gp68 (ascribable to trypsin activity plus CGP activity). Taking into account that only the vitelline envelopes of in vitro matured oocytes with trypsin treatment and activated can block sperm entry, we may suggest that the conversion of gp70 to gp68 is related to the changes associated with sperm binding.

Activation of maturation promoting factor in Bufo arenarum oocytes: injection of mature cytoplasm and germinal vesicle contents.

Although progesterone is the established maturation inducer in amphibians, Bufo arenarum oocytes obtained during the reproductive period (spring-summer) resume meiosis with no need of an exogenous hormonal stimulus if deprived of their enveloping follicle cells, a phenomenon called spontaneous maturation. In this species it is possible to obtain oocytes competent and incompetent to undergo spontaneous maturation according to the seasonal period in which animals are captured. Reinitiation of meiosis is regulated by maturation promoting factor (MPF), a complex of the cyclin-dependent kinase p34cdc2 and cyclin B. Although the function and molecule of MPF are common among species, the formation and activation mechanisms of MPF differ according to species. This study was undertaken to evaluate the presence of pre-MPF in Bufo arenarum oocytes incompetent to mature spontaneously and the effect of the injection of mature cytoplasm or germinal vesicle contents on the resumption of meiosis. The results of our treatment of Bufo arenarum immature oocytes incompetent to mature spontaneously with sodium metavanadate (NaVO3) and dexamethasone (DEX) indicates that these oocytes have a pre-MPF, which activates and induces germinal vesicle breakdown (GVBD) by dephosphorylation on Thr-14/Tyr-15 by cdc25 phosphatase and without cyclin B synthesis. The injection of cytoplasm containing active MPF is sufficient to activate an amplification loop that requires the activation of cdc25 and protein kinase C, the decrease in cAMP levels, and is independent of protein synthesis. However, the injection of germinal vesicle content also induces GVBD in the immature receptor oocyte, a process dependent on protein synthesis but not on cdc25 phosphatase or PKC activity.

Effect of insulin on spontaneous and progesterone-induced GVBD on Bufo arenarum denuded oocytes.

Progesterone is considered as the physiological steroid hormone that triggers meiosis reinitiation in amphibian oocytes. Nevertheless, isolated oocytes can be induced to undergo germinal vesicle breakdown (GVBD) in a saline medium by means of treatment with various hormones or inducing agents such as other steroid hormones, insulin or an insulin-like growth factor. It has been demonstrated that Bufo arenarum oocytes obtained during the reproductive period (spring-summer) resume meiosis with no need of an exogenous hormonal stimulus if deprived of their enveloping follicle cells, a phenomenon called spontaneous maturation. This study was undertaken to evaluate the participation of the purine and phosphoinositide pathway in the insulin-induced maturation of oocytes competent and incompetent to mature spontaneously, as well as to determine whether the activation of the maturation promoting factor (MPF) involved the activation of cdc25 phosphatase in Bufo arenarum denuded oocytes. Our results indicate that insulin was able to induce GBVD in oocytes incompetent to mature spontaneously and to enhance spontaneous and progesterone-induced maturation. In addition, high intracellular levels of purines such as cAMP or guanosine can reversibly inhibit the progesterone and insulin-induced maturation process in Bufo arenarum as well as spontaneous maturation. Assays of the inhibition of phosphatidylinositol-4,5-bisphosphate (PIP2) hydrolysis and its turnover by neomycin and lithium chloride respectively exhibited a different response in insulin- or progesterone-treated oocytes, suggesting that phosphoinositide turnover or hydrolysis of PIP2 is involved in progesterone- but not in insulin-induced maturation. In addition, the inhibitory effect of vanadate suggests that an inactive pre-maturation promoting factor (pre-MPF), activated by dephosphorylation of Thr-14 and Tyr-15 on p34cdc2, is present in Bufo arenarum full-grown oocytes; this step would be common to both spontaneous and hormone-induced maturation. The data presented here strongly suggest that insulin initiates at the cell surface a chain of events leading to GVBD. However, our studies point to the existence of certain differences between the steroid and the peptide hormone pathways, although both involve the decrease in intracellular levels of cAMP, the activation of phosphodiesterase (PDE) and the activation of pre-MPF.

Attitudes toward HIV-infected individuals and infection control practices among a group of dentists in Mexico City--a 1999 update of the 1992 survey.

BACKGROUND: The teaching of infection control (IC) was introduced at dental schools in Mexico during the 1990s. A 1992 survey indicated that some dentists had limited access to current IC standards. Deficient knowledge of bloodborne pathogens may influence dentists' attitudes about infected individuals and reduce compliance with IC recommendations. OBJECTIVE: To update the 1992 appraisal of attitudes about persons infected with HIV or the hepatitis B virus (HBV) and IC knowledge and practices in a nonrepresentative sample of dentists in Mexico City. METHOD: One hundred eighty dentists were interviewed in 1999 (response rate, 84.1%) with the same methods used in 1992. RESULTS: Seventy-nine percent of respondents perceived the risk of HIV infection as "considerable" to "very strong." The risk of HBV infection was considered higher than that of HIV. Only 32% of respondents had not been immunized against HBV. Reported use of personal protective equipment remained high. Dry heat was the preferred method for sterilization in 1992, but by 1999 it had been displaced by steam under pressure. Reported preference for more effective disinfectants was also evident overall. CONCLUSIONS: We found certain improvements in IC knowledge and practices between 1992 and 1999, and the results suggest targets for educational and regulatory efforts that are needed to promote better adherence to current IC standards.

Thanatophoric dysplasia: ultrasound diagnosis.

Six pregnant women with singleton fetuses were referred to our Prenatal Diagnostic Centers because of an initial diagnosis of intrauterine growth restriction (n = 4) or short femoral length (n = 2). We first examined the patients with two-dimensional (2D) ultrasonography (US), and then with three-dimensional (3D) US, and arrived at a definitive diagnosis of thanatophoric dysplasia. Although in experienced hands a diagnosis of thanatophoric dysplasia can be made with 2D US before the 24th week of gestation, our experience suggests that 3D US is a valuable complement to 2D US for the evaluation of fetuses with skeletal dysplasias.

Survey on attitudes toward HIV-infected individuals and infection control practices among dentists in Mexico City.

BACKGROUND: The teaching of infection control is gradually being introduced at dental schools in Mexico. However, most practicing dentists have limited access to current infection control standards. Deficiencies of knowledge with regard to blood-borne pathogens such as HIV and hepatitis B virus may influence attitudes toward infected individuals and reduce compliance with infection control recommendations. OBJECTIVE: The purpose of this study was to assess (1) attitudes toward HIV-infected patients and hepatitis B virus-infected patients and (2) infection control knowledge and practices among dental practitioners in Mexico City. METHOD: A total of 196 dentists were interviewed by means of a questionnaire with Likert-type scales and open-ended questions (response rate, 86.1%). RESULTS: Most respondents had no previous social or professional contact with HIV-positive individuals. Nine percent indicated that they had knowingly treated HIV-positive patients. Perceived professional and moral obligations to treat HIV-positive patients were high. Thirty-five percent of the respondents perceived the risk of HIV infection as "considerable" to "very strong." The risk of hepatitis B infection was considered significantly higher than the risk of HIV infection (P <.01); however, 78% of the respondents had not been immunized against hepatitis B. Reported use of personal protective equipment was high. Most respondents used dry heat sterilization. The principal disinfectants used were quaternary ammonium compounds, bleach, and glutaraldehyde. Fifty-four percent of the respondents acknowledged that clinical precautions reduced occupational risks. CONCLUSIONS: This survey revealed contradictory attitudes toward HIV-positive individuals and limited understanding of infection control recommendations. Educational and regulatory efforts are needed to promote better adherence to current infection control standards.

Fagocitosis de partículas de látex por macrófagos de ratón: influencia del tamaño de la partícula en su internación y en la liberación de lisozima / Phagocytosis of latex particles by mouse macrophages: influence of particle size on engulfment and lysozyme relase

Para determinar el comportamiento fagocítico de macrófagos en función del tamaño de partícula fagocitada, se cultivaron macrófagos peritoneales de ratón CBA in vitro durante 4, 24, 48, 72 y 96 h. Posteriormente se les incubó con partículas de látex opsonizadas (cinco grupos con partículas de 2, 6, 10, 15 y 25 µm de diámetro). En en grupo de 2 µg, 70.1 por ciento+ 5.7 de los macrófagos fagocitó las partículas, decreciendo progresivamente esta proporción (6 µm, 54.5 por ciento+ 4.9; 10 µm, 25.5 por ciento+ 6.6) hasta el grupo de 15 µm (0.33 por ciento + 0.2). La fagocitosis estuvo inversamente correlacionada al tamaño de las partículas (r=-0.9). No hubo fagocitosis en el ensayo de 25 µm. Mediante microscopía electrónica de barrido se pudo observar que en todos los grupos se estableció un contacto entre partículas de látex y macrófagos. En todos los grupos hubo liberación de lisozima, encontrándose que una mayor liberación estuvo asociada a un tamaño de partícula más grande (r=0.91). Nuestros resultados apoyan el concepto de que la fagocitosis está limitada por el tamaño de la partícula y que el contacto con éstas provoca degranulación, fenómeno que puede dar lugar a la muerte de organismo (p.ej., bacterias) cuando son atacados por enzimas liberadas por los macrófagos.