A model for the control of malaria using genetically modified vectors.

Recent works have considered the problem of using transgenic mosquitoes to control a malaria epidemic. These insects have been genetically engineered to reduce their capacity to infect humans with malaria parasites. We analyze a model of the mosquito population dynamics when genetically modified individuals are introduced into a wild type population so that the effect of their introduction can be assessed. The model describes the dynamics of gene selection under sexual reproduction in a closed vector population. Our results show that the fitness of the resulting heterozygous population is the key parameter for the success of the invasion, independently of the fitness of homozygous vectors. The vector population dynamics model is then combined with an epidemiological model to study the feasibility of controlling a malaria epidemic. Basic reproductive numbers are calculated for both models, and conditions are obtained for preventing reappearance of the epidemic. Simulations on this model show that it may be possible to reduce or even eradicate the epidemic only if the heterozygous population is better adapted than the wild type. They also show that this can be achieved without completely eliminating the wild type mosquitoes.

Enfoque del paciente con intoxicación aguda por plaguicidas organofosforados / Treatment of patient with organic phosphorus compounds poisoning

Un gran número de insecticidas organofosforados se usan en todo el mundo a diario. Las intoxicaciones ocurren generalmente de forma accidental por exposición laboral, o intencional, con fines suicidas. Los organofosforados producen sus efectos tóxicos a través de la inhibición de la acetilcolinesterasa, la enzima responsable de la hidrólisis del neurotransmisor acetilcolina, produciendo ácido acético y colina, productos químicamente inertes. La unión entre los organofosforados y la acetilcolina es una unión irreversible espontáneamente, sin embargo, puede ser reversible con el uso de antídotos específico llamados oximas. La administración temprana de pralidoxima es crucial y muy útil si se inicia en las primeras seis horas luego de la intoxicación aguda. La atropina produce un beneficio clínico dramático para los síntomas muscarínicos del síndrome colinérgico. Pueden ocurrir complicaciones importantes en los pacientes por intoxicación con organofosforados, y aún disfunción cerebral severa

Donación voluntaria y altruista de sangre desde un enfoque de promoción de la salud / Voluntary and altruistic donation of blood from an approach to health promotion

A través de la donación voluntaria y altruista de sangre, en el país, se pretende educar a la gente en estilos de vida saludables para que tengan una mejor salud, y a la vez que las personas saludables que deseen se conviertan en donantes voluntarios, de manera tal que se de un estatus al donante por el reconocimiento social que es la retribución al acto altruista de donación.

Políticas de comunicación en Salud / Policies of communicating for health

El capitulo presenta politicas de comunicacion en salud, politicas de comunicacion, politicas, estrategias y planes, experiencias de comunicacion para la salud en Bolivia, principios básicos de comunicacion par la salud pública.(au)

Release of merozoites from Plasmodium falciparum-infected erythrocytes could be mediated by a non-explosive event.

Little is known about the molecular mechanism underlying the release of merozoites from malaria-infected erythrocytes. In the present study, video microscopy was carried out, and images throughout the process of merozoite release from Plasmodium falciparum-infected erythrocytes were digitized and analyzed. Merozoites were shown to escape from the infected host cell in about 1 s through a single site of the infected erythrocyte membrane, whose dimension was estimated to be 2.5 microm. Merozoites were released together with the residual body containing hemozoin, leaving behind a membranous structure that persisted even after an extended period of observation. Densitometric measurements showed that the cytoplasmic content of the infected erythrocyte did not diffuse out as parasites were released, but was gradually lost thereafter. This would indicate that the release of merozoites from infected erythrocytes is not mediated by an explosive event.

Identification of novel membrane structures in Plasmodium falciparum infected erythrocytes.

Little is known about the molecular mechanisms underlying the release of merozoites from malaria infected erythrocytes. In this study membranous structures present in the culture medium at the time of merozoite release have been characterized. Biochemical and ultrastructural evidence indicate that membranous structures consist of the infected erythrocyte membrane, the parasitophorous vacuolar membrane and a residual body containing electron dense material. These are subcellular compartments expected in a structure that arises as a consequence of merozoite release from the infected cell. Ultrastructural studies show that a novel structure extends from the former parasite compartment to the surface membrane. Since these membrane modifications are detected only after merozoites have been released from the infected erythrocyte, it is proposed that they might play a role in the release of merozoites from the host cell.

Identification of peripheral membrane proteins associated with the tubo-vesicular network of Plasmodium falciparum infected erythrocytes.

During intracellular development of the malarial parasite numerous membranous vesicles appear in the infected erythrocyte cytoplasm between the parasitophorous vacuolar membrane (PVM) and the erythrocyte plasma membrane. In this study we describe the characterization of a monoclonal antibody which recognizes two major parasite-encoded proteins of 50 and 41 kDa. Immunofluorescence and immunoelectron microscopy demonstrated that the monoclonal antibody reacts with cytoplasmic vesicles of Plasmodium falciparum infected erythrocyte referred to as Maurer's clefts. The antigens recognized by the monoclonal antibody were expressed very early during the erythrocytic life cycle of the parasite, and remained tightly associated within membrane vesicles even after merozoites are released from infected erythrocytes. The antigens were partially soluble in non-ionic detergents, and were released from the membrane by alkali treatment, indicating that the proteins recognized by the monoclonal antibody are peripheral membrane proteins. It is proposed that the 50 and 41 kDa antigens might be part of an underlying membrane skeletal network that provides structural support to vesicles and tubules present in the infected erythrocyte cytoplasm.

Leptospirosis: presentación de un caso clínico / Leptospirosis: a clinical case report

A propósito de un caso clínico diagnosticado en 1995 en el Hospital San Juan de Dios, se revisa el tema de las leptospirosis. A pesar de ser una afección infrecuente de nuestro país, se destacan sus características clínicas y su importancia relativa en el diagnóstico diferencial de los síndromes febriles prolongados y de las ictericias. La leptospirosis corresponde a una enfermedad infecciosa aguda que se caracteriza por una extensa vasculitis provocada por una espiroqueta del género Leptospira. Es una zoonosis de distribución mundial y que puede infectar ocasionalmente al hombre por contacto directo con el reservorio animal o por transmisión indirecta, desarrollando la enfermedad. Típicamente se considera como una afección bifásica, con una etapa inicial septicémica y una segunda fase inmune. Se describen las formas clínicas de la enfermedad, las que se pueden clasificar en dos grupos: leptospirosis anistéricas que corresponden a la forma más común y benigna (90 porciento de los casos) y leptospirosis ictéricas o síndrome de Weil (10 porciento de los casos). Se consideran aspectos diagnósticos de la enfermedad el cual se realiza principalmente por cultivo en sangre, LCR y orina y serología. Se mencionan alternativas de tratamiento. La penicilina sódica en dosis habituales es el antibiótico de elección. En general, la enfermedad es de curso benigno cuando el diagnóstico y el tratamiento son precoces. En las formas graves la mortalidad alcanza hasta el 10 porciento

Failure of a synthetic vaccine to protect Aotus lemurinus against asexual blood stages of Plasmodium falciparum.

The hybrid synthetic protein SPf(66), which contains small fragments of the 83-kD, 55-kD, 35-kD, and circumsporozoite antigens of Plasmodium falciparum, was studied to determine its protective capacity against malaria infection in Aotus lemurinus monkeys. Two groups of six monkeys each were immunized six times with this polymer, which was mixed with either Freund's adjuvant or aluminum hydroxide. Two groups of five animals each were used as controls and immunized with saline solution mixed with the same adjuvants. Neither antipeptide nor antimalarial antibodies developed after the six immunization doses. Regardless of this fact, the monkeys were challenged intravenously with 10(5) P. falciparum blood stage parasites, and the resultant parasitemia was followed daily on blood smears. Only one monkey from each of the groups immunized using Freund's adjuvant (both experimental and control) was protected. In those immunized using aluminum hydroxide, one animal was protected in the experimental group, but none were protected in the control group. Anti-parasite antibodies developed during the infection, but did not correlate with protection and failed to recognize SPf(66) peptide in an enzyme-linked immunosorbent assay. Immunization with the polymer did not boost natural antibodies present in two of the monkeys before the experiment. Low levels of gamma-interferon were produced in some animals, but were not correlated with protection.