Arthrite rhumatoide traitée par noréthynodrel associée à mestranol: Aspects cliniques et tests de laboratoire

A cause de l''effet favorable de la grossesse sur l''activité de l''arthrite rhumatoïde, on s''est demandé si une pseudo-grossesse, produite par un progestatif de synthèse n''entraînerait pas une rémission du moins partielle de cette maladie.Noréthynodrel associée à mestranol (Enovid), 30 mg./jour, a été administrée à 44 femmes pendant quatre à 24 mois. A cause d''effets secondaires indésirables, 11 patientes furent soustraites de l''investigation. Les résultats s''appuient sur 33 cas. Une rémission apparente complète s''est manifestée chez sept patientes aux stades précoces de la maladie; chez 15, une amélioration objective des signes inflammatoires a été observée; chez quatre, une amélioration subjective seule a été notée; chez sept, il n''y a eu aucune amélioration. Dix-sept femmes sur 36 ont présenté une altération d''un ou plusieurs tests hépatiques. Trois présentèrent un ictère cholestatique. Les 17-OH plasmatiques se sont élevés à trois ou quatre fois la normale.De cette étude il ressort que noréthynodrel associée à mestranol peut produire une atténuation des signes inflammatoires de l''arthrite rhumatoïde. L''effet est palliatif, mitigé et non curatif et ne résulte pas nécessairement de l''état de pseudo-grossesse en soi.     

Differents aspects du fer dans l'organisme : I. Ferritine et micelles ferrugineuses

Des cellules réticulaires remplies de molécules de ferritine et d'hémosidérine se trouvent au centre "d'ilots érythroblastiques." Dans la zone de contact entre la cellule réticulaire chargée de ferritine et les érythroblastes, on voit des invaginations et des petites vacuoles au bord desquelles adhérent des molécules de ferritine. Il est postulé que la ferritine passe de la cellule réticulaire centrale dans les érythroblastes par ce mécanisme, apparenté à la pinocytose (rhophéocytose). Dans tous les érythroblastes normaux, il existe du fer sous forme de ferritine. Celle-ci peut se trouver à l'état dispersé ou agglomérée en amas. Lorsque ces amas sont assez gros, ils sont visibles au microscope optique: ce sont les granules des sidéroblastes. On trouve du fer dans les mitochondries, mais rarement à l'état normal. Il est soit sous forme de granules ferritiniques soit sous forme de micelles ferrugineuses. Dans les thalassémies et d'autres maladies s'accompagnant d'un trouble de l'hémoglobinogénèse, on trouve, en grande quantité, du fer visible au microscope électronique, dans les érythroblastes. Il s'y trouve sous forme de ferritine, en amas ou dispersé. Il existe parfois en grande quantité dans les mitochondries soit sous forme de ferritine, soit sous forme de micelles ferrugineuses. Il semble que soit objectivé ainsi le trouble de la synthèse de l'hémoglobine: le fer inutilisé s'accumule dans des érythroblastes hypochromes. Il est probable qu'à l'etat normal, le fer est métabolisé dans les mitochondries. Dans le thalassémies et les anémies hypochromes hypersidérémiques, il semble souvent bloqué dans ces organites.     

Differents aspects du fer dans l'organisme : II. Différentes formes de l'hémosidérine

On voit des molécules de ferritine apparaitre dans le cytoplasme des cellules réticulaires au cours de la digestion des érythrocytes, autour des stromas phagocytés. Cette ferritine s'accumule en amas dans lesquels entrent d'autres substances, en particulier des lipides, provenant aussi des stromas globulaires et qui apparaissent sous forme myélinique. Souvent la ferritine se dispose d'une manière cristalline. Parfois la ferritine et l'apoferritine alternent dans ces cristaux. Parfois l'hémosidérine contient des cristaux qui semblent bien être de l'apoferritine pure. L'injection de sels de fer donne lieu à l'apparition de ferritine dans les cellules réticulaires. Dans les conditions de nos expériences, la plus grande partie du fer injecté était sous forme de ferritine dans un délai de 3 jours. Un aspect intermédiaire entre celui du fer injecté et celui de la ferritine a été trouvé. Dans le cas des injections de saccharate de fer ce sont de fines aiguilles; dans le cas des injections de lactate de fer, il s'agit de masses fibreuses.     

Investigating the Role of Assessment Method on Reports of Déjà Vu and Tip-of-the-Tongue States during Standard Recognition Tests

Déjà vu and tip-of-the-tongue (TOT) are retrieval-related subjective experiences whose study relies on participant self-report. In four experiments (ns = 224, 273, 123 and 154), we explored the effect of questioning method on reported occurrence of déjà vu and TOT in experimental settings. All participants carried out a continuous recognition task, which was not expected to induce déjà vu or TOT, but were asked about their experiences of these subjective states. When presented with contemporary definitions, between 32% and 58% of participants nonetheless reported experiencing déjà vu or TOT. Changing the definition of déjà vu or asking participants to bring to mind a real-life instance of déjà vu or TOT before completing the recognition task had no impact on reporting rates. However, there was an indication that changing the method of requesting subjective reports impacted reporting of both experiences. More specifically, moving from the commonly used retrospective questioning (e.g. “Have you experienced déjà vu?”) to free report instructions (e.g. “Indicate whenever you experience déjà vu.”) reduced the total number of reported déjà vu and TOT occurrences. We suggest that research on subjective experiences should move toward free report assessments. Such a shift would potentially reduce the presence of false alarms in experimental work, thereby reducing the overestimation of subjective experiences prevalent in this area of research.     

Arsenotoxicidad aguda experimental en ratones Balb/c: marcadores orgánicos y compromiso esplénico

IntroducciónEl arsénico es un tóxico ambiental ampliamente diseminado en todo el mundo. En hombres y animales, diversos órganos y tejidos son blancos de sus efectos deletéreos, entre ellos, el los del sistema inmunológico.ObjetivoDeterminar la intoxicación aguda por arsénico en tejidos y células diana de ratones Balb/c in vivo.Materiales y métodosSe aplicó una inyección intraperitoneal de 9,5 o 19 mg/kg de arsenito de sodio (NaAsO₂) o un volumen equivalente de solución fisiológica como control, en ratones Balb/c con 3 por cada grupo experimental. Tras media hora, los animales fueron sacrificados y se extrajeron bazos, timos, hígados, riñones y sangre. En cada muestra, se determinó la concentración de arsénico, polifenoles y hierro, y también, se evaluaron marcadores oxidativos, como peróxidos, productos avanzados de oxidación proteica y grupos sulfhidrilos libres. En los esplenocitos obtenidos del bazo, se determinaron la viabilidad celular y el potencial mitocondrial.ResultadosLa dosis aguda inyectada de NaAsO₂ redujo la función mitocondrial de los esplenocitos, lo que derivó en muerte celular. La presencia confirmada de arsénico en las muestras de bazo y la citotoxicidad resultante, produjeron disminución de los polifenoles y de los grupos sulfhidrilos libres, y alteraron el contenido y la distribución del hierro, pero no se aumentó la producción de peróxidos.ConclusiónEstos hallazgos aportan evidencia científica sobre los cambios en biomarcadores involucrados en la inmunotoxicidad del arsénico y ofrecen, además, una metodología para ensayar potenciales tratamientos frente a la acción deletérea de este compuesto en el sistema inmunológico.Palabras clave: arsénico, toxicidad aguda, estrés oxidativo, sistema inmunológico, ratones     

Inserción “velamentosa”, encefalopatía hipóxico-isquémica y rehabilitación neurológica: reporte de caso

La encefalopatía hipóxico-isquémica es una causa frecuente e importante de daño neurológico en recién nacidos a término y prematuros. Un evento centinela de esta condición es la vasa previa, específicamente cuando existe anormalidad de la placenta como la inserción “velamentosa” del cordón umbilical. Algunos reportes evidencian la asociación entre estas dos condiciones, pero son escasos los que dan cuenta del proceso de recuperación y del pronóstico neurológico de los niños afectados por ellas.Se presenta el caso de un paciente, con antecedentes de inserción “velamentosa” del cordón umbilical y encefalopatía hipóxico-isquémica, que recibió hipotermia terapéutica (cool cap). Se describe su proceso de rehabilitación neurológica y se calculó el porcentaje de probabilidad de presentar esta condición frente a la población sin estos factores. El niño tenía cinco años y el puntaje en su prueba de Apgar fue de 0 al minuto y de 2 a los 15 minutos. Desarrolló encefalopatía hipóxico-isquémica grave secundaria a una inserción “velamentosa” del cordón umbilical sin diagnóstico prenatal, con gran compromiso neurológico y multisistémico inicial. El proceso de recuperación incluyó el manejo inicial multidisciplinario en la unidad de cuidados intensivos neonatales y el inicio temprano de habilitación neurológica.Hoy el niño está escolarizado y en terapia integral, no presenta deficiencias motoras ni sensoriales en el examen físico, aunque la prueba neuropsicológica sugiere un riesgo de trastorno por déficit de atención e hiperactividad. Habitualmente, los niños con encefalopatía hipóxico-isquémica grave presentan discapacidad por deficiencias motoras, cognitivas o conductuales. El haber recibido hipotermia terapéutica y un manejo estructurado de rehabilitación redujo en gran medida las deficiencias esperadas y ha promovido un satisfactorio desarrollo físico y neurológico.Palabras clave: cordón umbilical, hipoxia-isquemia encefálica, hipotermia inducida, rehabilitación neurológica     

Efectos adversos de las sustancias modelantes en Cali,Colombia

IntroducciónEl deseo de mejorar la apariencia física mediante métodos sencillos y económicos, ha generado la aplicación indiscriminada de sustancias modelantes y, con ello, el surgimiento de la alogenosis iatrogénica, enfermedad cada vez más prevalente en Latinoamérica.ObjetivoDescribir las características epidemiológicas y los efectos adversos de las sustancias modelantes en un grupo de pacientes de Cali, Colombia.Materiales y métodosSe hizo una revisión retrospectiva de las historias clínicas de los pacientes que acudieron a consulta por complicaciones producidas por sustancias modelantes durante un sexenio.ResultadosSe incluyeron 1.322 pacientes, 95,5% de ellos mujeres. Las edades oscilaron entre los 19 y los 83 años, con una media de 39 años. El sitio anatómico de infiltración con sustancias modelantes con mayor frecuencia de efectos adversos, fueron los glúteos. La asimetría y el aumento del volumen en el sitio infiltrado fueron los signos más comunes, en tanto que el dolor, las alteraciones del ánimo y la depresión o la ansiedad fueron los síntomas más percibidos. El 33,6% de los pacientes desconocía la sustancia aplicada y el 28,1% refirió haberse aplicado biopolímeros. La mayoría de estos procedimientos estuvo a cargo de personal sin la debida formación.ConclusionesEstos pacientes requieren la atención de equipos multidisciplinarios para establecer alternativas de tratamiento que mejoren su calidad de vida. Además, se necesitan la regulación de los establecimientos, y las medidas de vigilancia, inspección y control en la importación y el uso de estas sustancias.Palabras clave: biopolímeros, efectos adversos, enfermedad iatrogénica, contraindicaciones de los procedimientos, estética, procedimientos quirúrgicos reconstructivos     

Cardiovascular Disease Rates,Outcomes, and Quality of Care in Ontario Métis: A Population-Based Cohort Study

Background

The burden of cardiovascular disease in the Métis, Canada’s fastest growing Aboriginal group, is not well studied. We determined rates of five cardiovascular diseases and associated outcomes in Ontario Métis, compared to the general Ontario population.

Methods

Métis persons were identified using the Métis Nation of Ontario Citizenship Registry. Métis citizens aged 20–105 were linked to Ontario health databases for the period of April 2006 to March 2011. Age- and sex-standardized prevalence and incidence of acute coronary syndromes (ACS), congestive heart failure (CHF), cerebrovascular disease (stroke), atrial fibrillation, and hypertension were compared between the Métis and the general population. Secondary outcome measures included one-year hospitalizations and mortality following the incident cardiovascular diagnosis, as well as quality-of-care measures.

Results

There were 12,550 eligible Métis persons and 10,144,002 in the general population. The adjusted prevalence of each disease was higher (p<0.05) among the Métis compared to the general population: ACS 5.3% vs. 3.0%; CHF 5.1% vs. 3.9%; stroke 1.4% vs. 1.1%; atrial fibrillation 2.1% vs. 1.4%; hypertension 34.9% vs. 29.8%. Incident ACS, stroke, and atrial fibrillation were also higher (p<0.05) among the Métis: ACS 2.4% vs. 1.5%; stroke 0.8% vs. 0.6%; atrial fibrillation 0.6% vs. 0.3%. One-year all-cause and cardiovascular-related mortality were not significantly different. Hospitalizations were higher for Métis persons with CHF (OR 1.93; 95% CI 1.34–2.78) and hypertension (OR 2.27; 95% CI 1.88–2.74). Métis with CHF made more emergency department (ED) visits in the year after diagnosis compared to non-Métis with CHF, while Métis aged ≥65 with ACS were more likely to be on beta-blockers following diagnosis.

Conclusions

The burden of cardiovascular disease was markedly higher in the Métis compared to the general population: prevalence rates for five cardiovascular conditions were 25% to 77% higher. Métis persons with CHF had more frequent hospitalizations and ED visits following their diagnosis.     

Metaciclogénesis de Trypanosoma cruzi en Belminus ferroae (Reduviidae: Triatominae) y capacidad infectiva de las heces en condiciones de laboratorio

IntroducciónBelminus ferroae es un triatomino de comportamiento entomófago, sin embargo, puede alimentarse de vertebrados ocasionalmente. No se ha demostrado infección natural por Trypanosoma cruzi en esta especie, como tampoco la metaciclogénesis del parásito.ObjetivoExaminar la metaciclogénesis de T. cruzi en B. ferroae y la capacidad infectiva de las heces o sus contenidos intestinales en roedores.Materiales y métodosSe analizaron las heces y la orina expulsadas espontáneamente por los insectos o mediante compresión abdominal o extracción del contenido intestinal a los 10, 20, 30, 40, 50 y 60 días. Se cuantificó la carga parasitaria de T. cruzi y sus formas evolutivas se identificaron con tinción de Giemsa. Asimismo, se evaluó en ratones albinos la capacidad infectiva de los tripomastigotes metacíclicos de T. cruzi obtenidos de las heces o contenidos intestinales de los especímenes infectados.ResultadosEl análisis parasitológico reveló tres (15%) insectos infectados con T. cruzi a los 30 (n=1), 40 (n=1) y 50 (n=1) días después de la infección con cargas parasitarias de hasta 1,62 x 10⁵ tripanosomas/mm³ y porcentajes de metaciclogénesis entre el 3,5 y el 6,78%.ConclusionesSe demuestra por primera vez, en una especie del género Belminus. la metaciclogenésis de T. cruzi en condiciones de laboratorio y la capacidad infectiva de las heces para un huésped vertebrado.Palabras clave: Trypanosoma cruzi, Triatominae, enfermedad de Chagas, tripanosomiasis     

Asthma and Chronic Obstructive Pulmonary Disease (COPD) Prevalence and Health Services Use in Ontario Métis: A Population-Based Cohort Study

Introduction

Chronic respiratory diseases cause a significant health and economic burden around the world. In Canada, Aboriginal populations are at increased risk of asthma and chronic obstructive pulmonary disease (COPD). There is little known, however, about these diseases in the Canadian Métis population, who have mixed Aboriginal and European ancestry. A population-based study was conducted to quantify asthma and COPD prevalence and health services use in the Métis population of Ontario, Canada’s largest province.

Methods

The Métis Nation of Ontario Citizenship Registry was linked to provincial health administrative databases to measure and compare burden of asthma and COPD between the Métis and non-Métis populations of Ontario between 2009 and 2012. Asthma and COPD prevalence, health services use (general physician and specialist visits, emergency department visits, hospitalizations), and mortality were measured.

Results

Prevalences of asthma and COPD were 30% and 70% higher, respectively, in the Métis compared to the general Ontario population (p<0.001). General physician and specialist visits were significantly lower in Métis with asthma, while general physician visits for COPD were significantly higher. Emergency department visits and hospitalizations were generally higher for Métis compared to non-Métis with either disease. All-cause mortality in Métis with COPD was 1.3 times higher compared to non-Métis with COPD (p = 0.01).

Conclusion

There is a high burden of asthma and COPD in Ontario Métis, with significant prevalence and acute health services use related to these diseases. Lower rates of physician visits suggest barriers in access to primary care services.     

Truffle Br?lés Have an Impact on the Diversity of Soil Bacterial Communities

Background

The development of Tuber melanosporum mycorrhizal symbiosis is associated with the production of an area devoid of vegetation (commonly referred to by the French word ‘brûlé’) around the symbiotic plants and where the fruiting bodies of T. melanosporum are usually collected. The extent of the ecological impact of such an area is still being discovered. While the relationship between T. melanosporum and the other fungi present in the brûlé has been assessed, no data are available on the relationship between this fungus and the bacteria inhabiting the brûlé.

Methodology/Principal Findings

We used DGGE and DNA microarrays of 16S rRNA gene fragments to compare the bacterial and archaeal communities inside and outside of truffle brûlés. Soil samples were collected in 2008 from four productive T. melanosporum/Quercus pubescens truffle-grounds located in Cahors, France, showing characteristic truffle brûlé. All the samples were analyzed by DGGE and one truffle-ground was analyzed also using phylogenetic microarrays. DGGE profiles showed differences in the bacterial community composition, and the microarrays revealed a few differences in relative richness between the brûlé interior and exterior zones, as well as differences in the relative abundance of several taxa.

Conclusions/Significance

The different signal intensities we have measured for members of bacteria and archaea inside versus outside the brûlé are the first demonstration, to our knowledge, that not only fungal communities, but also other microorganisms are affected by T. melanosporum. Firmicutes (e.g., Bacillus), several genera of Actinobacteria, and a few Cyanobacteria had greater representation inside the brûlé compared with outside, whereas Pseudomonas and several genera within the class Flavobacteriaceae had higher relative abundances outside the brûlé. The findings from this study may contribute to future searches for microbial bio-indicators of brûlés.     

Adaptive Lévy Processes and Area-Restricted Search in Human Foraging

A considerable amount of research has claimed that animals’ foraging behaviors display movement lengths with power-law distributed tails, characteristic of Lévy flights and Lévy walks. Though these claims have recently come into question, the proposal that many animals forage using Lévy processes nonetheless remains. A Lévy process does not consider when or where resources are encountered, and samples movement lengths independently of past experience. However, Lévy processes too have come into question based on the observation that in patchy resource environments resource-sensitive foraging strategies, like area-restricted search, perform better than Lévy flights yet can still generate heavy-tailed distributions of movement lengths. To investigate these questions further, we tracked humans as they searched for hidden resources in an open-field virtual environment, with either patchy or dispersed resource distributions. Supporting previous research, for both conditions logarithmic binning methods were consistent with Lévy flights and rank-frequency methods–comparing alternative distributions using maximum likelihood methods–showed the strongest support for bounded power-law distributions (truncated Lévy flights). However, goodness-of-fit tests found that even bounded power-law distributions only accurately characterized movement behavior for 4 (out of 32) participants. Moreover, paths in the patchy environment (but not the dispersed environment) showed a transition to intensive search following resource encounters, characteristic of area-restricted search. Transferring paths between environments revealed that paths generated in the patchy environment were adapted to that environment. Our results suggest that though power-law distributions do not accurately reflect human search, Lévy processes may still describe movement in dispersed environments, but not in patchy environments–where search was area-restricted. Furthermore, our results indicate that search strategies cannot be inferred without knowing how organisms respond to resources–as both patched and dispersed conditions led to similar Lévy-like movement distributions.     

Costos directos de la infección adquirida en la comunidad por neonatos a término con bajo riesgo al nacer,Cundinamarca, Colombia

IntroducciónEl 50% de los episodios de sepsis neonatal se originan en la comunidad, con un gran porcentaje de mortalidad y complicaciones.ObjetivoEstimar los costos directos de la hospitalización por infección neonatal adquirida en la comunidad en neonatos a término con bajo riesgo al nacer.Materiales y métodosSe utilizó la perspectiva del tercer pagador y la técnica de microcosteo; el horizonte de tiempo fue la duración de la hospitalización. La determinación de las situaciones generadoras de costos se obtuvo por medio de un consenso de expertos y se cuantificaron con base en la factura detallada de la atención de 337 neonatos hospitalizados. Los costos de los medicamentos se calcularon con base en el Sistema de Información de Precios de Medicamentos (SISMED) y, el de los procedimientos, según los manuales tarifarios ISS 2001 con porcentaje de ajuste y el seguro obligatorio de accidentes de tráfico (SOAT). Para incorporar la variabilidad de la información en la estimación, se obtuvo una distribución de los costos usando el método de bootstrapping.ResultadosSe incluyeron las facturas por la atención de 337 recién nacidos. El promedio de costos directos de la atención por paciente fue de COL$ 2’773.965 (desviación estándar, DE=$ 198.813,5; IC_95%: $ 2’384.298 - $ 3’163.632). Las principales categorías generadoras de costos fueron la internación en la unidad de cuidados intensivos y las tecnologías en salud. Los costos siguieron una una distribución logarítmica normal (log-normal).ConclusionesLas categorías con mayor impacto en los costos fueron la internación en la unidad neonatal y las tecnologías en salud. Los costos se ajustaron a una distribución logarítmica normal.Palabras clave: sepsis neonatal, costos y análisis de costo, recién nacido, unidades de cuidado intensivo neonatal, mortalidad infantil     

Serologically Defined Variations in Malaria Endemicity in Pará State,Brazil

Background

Measurement of malaria endemicity is typically based on vector or parasite measures. A complementary approach is the detection of parasite specific IgG antibodies. We determined the antibody levels and seroconversion rates to both P. vivax and P. falciparum merozoite antigens in individuals living in areas of varying P. vivax endemicity in Pará state, Brazilian Amazon region.

Methodology/Principal Findings

The prevalence of antibodies to recombinant antigens from P. vivax and P. falciparum was determined in 1,330 individuals. Cross sectional surveys were conducted in the north of Brazil in Anajás, Belém, Goianésia do Pará, Jacareacanga, Itaituba, Trairão, all in the Pará state, and Sucuriju, a free-malaria site in the neighboring state Amapá. Seroprevalence to any P. vivax antigens (MSP1 or AMA-1) was 52.5%, whereas 24.7% of the individuals were seropositive to any P. falciparum antigens (MSP1 or AMA-1). For P. vivax antigens, the seroconversion rates (SCR) ranged from 0.005 (Sucuriju) to 0.201 (Goianésia do Pará), and are strongly correlated to the corresponding Annual Parasite Index (API). We detected two sites with distinct characteristics: Goianésia do Pará where seroprevalence curve does not change with age, and Sucuriju where seroprevalence curve is better described by a model with two SCRs compatible with a decrease in force of infection occurred 14 years ago (from 0.069 to 0.005). For P. falciparum antigens, current SCR estimates varied from 0.002 (Belém) to 0.018 (Goianésia do Pará). We also detected a putative decrease in disease transmission occurred ∼29 years ago in Anajás, Goianésia do Pará, Itaituba, Jacareacanga, and Trairão.

Conclusions

We observed heterogeneity of serological indices across study sites with different endemicity levels and temporal changes in the force of infection in some of the sites. Our study provides further evidence that serology can be used to measure and monitor transmission of both major species of malaria parasite.     

Older Russian emigrés and medical care.

Although emigration from the former Soviet Union is dramatically increasing nationwide, little information has been reported on the medical problems of these emigrés. For older emigrés in particular, the medical realities of aging, in combination with cultural expectations, make the United States'' medical system an arena where the stresses of emigration are expressed and help is sought. We describe the influences of culture and aging on older emigrés'' health and interaction with the American medical system. A qualitative, exploratory study was done of problems and issues in health care use by older Russian emigrés at the ambulatory medical clinic of Mount Zion Medical Center, San Francisco. Cultural expectations and beliefs about health, adaptive health behaviors learned in the former Soviet Union, the stresses of emigration, and the medical realities of aging can result in serious problems in the care and treatment of older Russian emigrés. Recommended solutions include educating emigrés and health care professionals, integrating mental health services into the primary care setting, and expanding supportive services in the community such as adult day health care.     

Adaptive Lévy Walks in Foraging Fallow Deer

Background

Lévy flights are random walks, the step lengths of which come from probability distributions with heavy power-law tails, such that clusters of short steps are connected by rare long steps. Lévy walks maximise search efficiency of mobile foragers. Recently, several studies raised some concerns about the reliability of the statistical analysis used in previous analyses. Further, it is unclear whether Lévy walks represent adaptive strategies or emergent properties determined by the interaction between foragers and resource distribution. Thus two fundamental questions still need to be addressed: the presence of Lévy walks in the wild and whether or not they represent a form of adaptive behaviour.

Methodology/Principal Findings

We studied 235 paths of solitary and clustered (i.e. foraging in group) fallow deer (Dama dama), exploiting the same pasture. We used maximum likelihood estimation for discriminating between a power-tailed distribution and the exponential alternative and rank/frequency plots to discriminate between Lévy walks and composite Brownian walks. We showed that solitary deer perform Lévy searches, while clustered animals did not adopt that strategy.

Conclusion/Significance

Our demonstration of the presence of Lévy walks is, at our knowledge, the first available which adopts up-to-date statistical methodologies in a terrestrial mammal. Comparing solitary and clustered deer, we concluded that the Lévy walks of solitary deer represent an adaptation maximising encounter rates with forage resources and not an epiphenomenon induced by a peculiar food distribution.     

Cellular hypersensitivity in Guillain-Barré syndrome

The Guillain-Barré syndrome is hypothesized to be secondary to cellular hypersensitivity to peripheral nerve antigens. To test this theory lymphocytes from 100 subjects were studied using the macrophage-migration-inhibition factor (MIF) assay. Thirty-four normal controls gave a mean migration of 100.4 ± 9%. Of 34 patients with peripheral nervous system disease, only those with the Guillain-Barré syndrome showed hypersensitivity with a mean migration of 72 ± 11%. Of 34 patients with central nervous system disease only three with multiple sclerosis and two with stroke gave similar results. Positive results in the Guillain-Barré syndrome were found only in patients presenting with classical disease and who were ill at the time of study.     

Fast Waves at the Base of the Cochlea

Georg von Békésy observed that the onset times of responses to brief-duration stimuli vary as a function of distance from the stapes, with basal regions starting to move earlier than apical ones. He noticed that the speed of signal propagation along the cochlea is slow when compared with the speed of sound in water. Fast traveling waves have been recorded in the cochlea, but their existence is interpreted as the result of an experiment artifact. Accounts of the timing of vibration onsets at the base of the cochlea generally agree with Békésy’s results. Some authors, however, have argued that the measured delays are too short for consistency with Békésy’s theory. To investigate the speed of the traveling wave at the base of the cochlea, we analyzed basilar membrane (BM) responses to clicks recorded at several locations in the base of the chinchilla cochlea. The initial component of the BM response matches remarkably well the initial component of the stapes response, after a 4-μs delay of the latter. A similar conclusion is reached by analyzing onset times of time-domain gain functions, which correspond to BM click responses normalized by middle-ear input. Our results suggest that BM responses to clicks arise from a combination of fast and slow traveling waves.