Subjective time under altered states of consciousness in ayahuasca users in shamanistic rituals involving music

Ayahuasca is described as a hallucinogenic substance whose property is to alter the subjective experience of time and impair the perception of the passage of time during stimuli of more than two to three seconds. The dose-dependent effects of two concentrations of ayahuasca in the ritualistic context were investigated employing temporal reproduction tasks in participants experienced in shamanistic ayahuasca rituals. The study was conducted on nine healthy volunteers who ingested two doses of ayahuasca at two times during a ritual session. The doses of each session, consumed in amounts ranging from 20 to 60 mL, were either of low concentration or of experimental ayahuasca according to a double-blind procedure. Participants performed the task of immediately listening and reproducing, with a laptop, 20-s musical stimuli during the session. The results showed that significant temporal distortion was triggered by the musical stimulus presented without the ingestion of ayahuasca, with means of 16.33 to 16.52 s. There were minor temporal distortions after ingestion of ayahuasca: a mean of 17.91 s for control ayahuasca and of 18.38 s for experimental ayahuasca. These results with less temporal distortion among participants with ayahuasca intake disagree with other studies of hallucinogens involving temporal reproduction.

VEGF receptor expression decreases during lung development in congenital diaphragmatic hernia induced by nitrofen

Changes in vascular endothelial growth factor (VEGF) in pulmonary vessels have been described in congenital diaphragmatic hernia (CDH) and may contribute to the development of pulmonary hypoplasia and hypertension; however, how the expression of VEGF receptors changes during fetal lung development in CDH is not understood. The aim of this study was to compare morphological evolution with expression of VEGF receptors, VEGFR1 (Flt-1) and VEGFR2 (Flk-1), in pseudoglandular, canalicular, and saccular stages of lung development in normal rat fetuses and in fetuses with CDH. Pregnant rats were divided into four groups (n=20 fetuses each) of four different gestational days (GD) 18.5, 19.5, 20.5, 21.5: external control (EC), exposed to olive oil (OO), exposed to 100 mg nitrofen, by gavage, without CDH (N-), and exposed to nitrofen with CDH (CDH) on GD 9.5 (term=22 days). The morphological variables studied were: body weight (BW), total lung weight (TLW), left lung weight, TLW/BW ratio, total lung volume, and left lung volume. The histometric variables studied were: left lung parenchymal area density and left lung parenchymal volume. VEGFR1 and VEGFR2 expression were determined by Western blotting. The data were analyzed using analysis of variance with the Tukey-Kramer post hoc test. CDH frequency was 37% (80/216). All the morphological and histometric variables were reduced in the N- and CDH groups compared with the controls, and reductions were more pronounced in the CDH group (P<0.05) and more evident on GD 20.5 and GD 21.5. Similar results were observed for VEGFR1 and VEGFR2 expression. We conclude that N- and CDH fetuses showed primary pulmonary hypoplasia, with a decrease in VEGFR1 and VEGFR2 expression.

Cultivo in vitro de Brosimum gaudichaudii Tréc. (Moraceae) / In vitro cultivation of Brosimum gaudichaudii Tréc. (Moraceae)

O objetivo desta pesquisa foi avaliar o potencial organogenético de entrenós, discos foliares, e raízes de Brosimum gaudichaudii utilizando 12 diferentes combinações dos fitorreguladores 6-benzilaminopurina e ácido naftaleno acético, em meio MS (diluído à metade), sólido (6,5 g de ágar), e com 20 g.L-1 de sacarose. Independentemente das combinações hormonais testadas verificou-se a formação de calos friáveis (2 a 20 mm de diâmetro) em 90% dos entrenós usados como explantes. No entanto, os tratamentos testados não foram capazes induzir calos ou gemas em raízes e em discos foliares. O estudo anatômico revelou a formação de meristemóides nas regiões mais externa e mais interna dos calos. Os resultados obtidos poderão servir de base para novos testes de indução de calos na espécie.

The objective of this research was to evaluate the organogenic potential of internodes, leaf discs and roots of Brosimum gaudichaudii using 12 different combinations of the plant growth regulators 6-benzylaminopurine and naphthalene acetic acid in MS medium (half strength), solid medium (6.5 g agar) and sucrose medium (20 g.L-1). Regardless the hormonal combination tested, we observed the formation of friable calluses (2 - 20 mm wide) in 90% of the internode explants. However, the treatments were not able to induce callus or buds on roots and leaf discs. The anatomical analysis revealed meristemoid formation in the outer and inner regions of the calluses. The results may serve as the basis for further testing of callus induction in this species.

Efeito da temperatura ambiente e da idade do frango sobre o valor energético do farelo de soja / Effects of environmental temperature and age of broilers on energy value of soybean meal

Foram utilizados 288 pintos de corte Cobb, distribuídos em delineamento experimental inteiramente ao acaso, em esquema de parcelas subdivididas no tempo, sendo as três temperaturas de criação - fria, termoneutra e quente - as parcelas, e as três fases de avaliação - inicial, crescimento e final - as subparcelas, com seis repetições de seis aves cada. A dieta-teste foi obtida pela substituição de parte da ração basal pelo alimento-teste: 40 por cento do farelo de soja + 60 por cento da ração basal. Foram calculados os coeficientes de metabolizabilidade aparente e verdadeiro da matéria seca, do nitrogênio, do extrato etéreo da dieta-teste e os valores de energia metabolizável aparente e verdadeira (EMA e EMV), e corrigidas pelo balanço de nitrogênio do farelo de soja (EMAn e EMVn). Foram encontrados valores médios de EMAn do farelo de soja para aves criadas em temperatura fria, termoneutra e quente de 2110, 2016 e 2022kcal/kg, respectivamente, e para as fases de criação inicial, crescimento e final de 1840, 2052 e 2256kcal/kg, respectivamente. O valor de energia metabolizável do farelo de soja, os balanços e os coeficientes de metabolizabilidade dos nutrientes da dieta-teste aumentaram com a idade do frango de corte, porém não são afetados pela temperatura ambiente.

Two hundred and eighty-eight Cobb chicks were distributed in a completely randomized design with a split-plot arrangement with six replication of six chicks each, the main plots were in three temperatures (cold, thermo neutral and hot) and the secondary plot were by phase (initial, growing and final). The test diet was produced by replacing the basal diet with test food: 40 percent soybean meal+60 percent basal diet. The coefficient of apparent and true metabolizability of dry matter, nitrogen, ether extract of the test diet and apparent and true metabolizable energies (AME and TME) of soybean meal were calculated and energy values were corrected for nitrogen balance (AMEn and TMEn) of soybean meal, in kcal/kg, as fed basis. The mean values of AMEn observed for broiler chicks in cold, thermo neutral and hot temperature were 2110, 2016 and 2022kcal/kg, respectively, and the initial, growing and final phases were 1840, 2052 and 2256kcal/kg, respectively. The metabolizable energy values of soybean meal, the balance and coefficients of metabolizability of the nutrients of the test diet increased with the age of broiler; however, they were not affected by environmental temperature.

Inflammatory response in a rat model of gastroschisis is associated with an increase of NF-kappaB

Babies with gastroschisis have high morbidity, which is associated with inflammatory bowel injury caused by exposure to amniotic fluid. The objective of this study was to identify components of the inflammatory response in the intestine and liver in an experimental model of gastroschisis in rats. The model was surgically created at 18.5 days of gestation. The fetuses were exposed through a hysterotomy and an incision at the right of the umbilicus was made, exposing the fetal bowel. Then, the fetus was placed back into the uterus until term. The bowel in this model had macro- and microscopic characteristics similar to those observed in gastroschisis. The study was conducted on three groups of 20 fetuses each: gastroschisis, control, and sham fetuses. Fetal body, intestine and liver weights and intestine length were measured. IL-1â, IL-6, IL-10, TNF-á, IFN-ã and NF-kappaB levels were assessed by ELISA. Data were analyzed statistically by ANOVA followed by the Tukey post-test. Gastroschisis fetuses had a decreased intestine length (means ± SD, 125 ± 25 vs 216 ± 13.9; P < 0.005) and increased intestine weight (0.29 ± 0.05 vs 0.24 ± 0.04; P < 0.005). Intestine length correlated with liver weight only in gastroschisis fetuses (Pearson’s correlation coefficient, r = 0.518, P = 0.019). There were no significant differences in the concentrations of IL-1â, TNF-á or IFN-ã in the intestine, whereas the concentration of NF-kappaB was increased in both the intestine and liver of fetuses with gastroschisis. These results show that the inflammatory response in the liver and intestine of the rat model of gastroschisis is accompanied by an increase in the amount of NF-kappaB in the intestine and liver.

Situação epidemiológica da brucelose bovina no Estado do Rio de Janeiro / Epidemiological situation of bovine brucellosis in the State of Rio de Janeiro, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina no Estado do Rio de Janeiro. O Estado foi dividido em três circuitos produtores. Em cada circuito foram amostradas aleatoriamente cerca de 300 propriedades e, dentro dessas, foi escolhido, de forma aleatória, um número pré-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total foram amostrados 8239 animais, provenientes de 945 propriedades. Em cada propriedade amostrada foi aplicado um questionário epidemiológico para verificar o tipo de exploração e as práticas zootécnicas e sanitárias que poderiam estar associadas ao risco de infecção pela doença. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e reteste dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo se pelo menos um animal foi reagente às duas provas sorológicas. Para o Estado, as prevalências de focos e de animais infectados foram, respectivamente, de 15,4 por cento [12,9-17,9 por cento] e de 4,1 por cento [2,8-5,3 por cento]. Para os circuitos, as prevalências de focos e de animais infectados foram, respectivamente: circuito 1, 13,8 por cento [10,2-18,2 por cento] e 3,0 por cento [1,9-4,1 por cento]; circuito 2, 15,7 por cento [11,9-20,2 por cento] e 2,3 por cento [1,4-3,2 por cento]; circuito 3, 19,6 por cento [15,4-24,4 por cento] e 9,3 por cento [4,5-14,1 por cento]. Os fatores de risco (odds ratio, OR) associados à condição de foco foram: ter mais que 30 fêmeas com idade de 24 meses ou acima (OR=2,33 [1,51-3,07]), compra de reprodutores (OR= 1,95 [1,13-2,45]) e prática de aluguel de pasto (OR= 1,74 [1,03-2,74]).

A study to characterize the epidemiological status of bovine brucellosis in the State of Rio de Janeiro was carried out. The State was divided in three regions. Three hundred herds were randomly sampled in each region and a pre-established number of animals were sampled in each herd. A total of 8,239 serum samples from 945 herds were collected. In each herd, it was applied an epidemiological questionnaire focused on herd traits as well as husbandry and sanitary practices that could be associated with the risk of infection. The serum samples were screened for antibodies against Brucella spp. by the Rose-Bengal Test (RBT), and all positive sera were re-tested by the 2-mercaptoethanol test (2-ME). The herd was considered positive if at least one animal was positive on both RBT and 2-ME tests. The prevalences of infected herds and animals in the State were, respectively: 15.4 percent [12.9-17.9 percent] and 4.1 percent [2.8-5.3 percent]. The prevalences of infected herds and animals in the regions were, respectively: region 1, 13.8 percent [10.2-18.2 percent] and 3.0 percent [1.9-4.1 percent]; region 2, 15.7 percent [11.9-20.2 percent] and 2.3 percent [1.4-3.2 percent]; and region 3, 19.6 percent [15.4-24.4 percent] and 9.3 percent [4.5-14.1 percent]. The risk factors (odds ratio, OR) associated with the presence of the infection were: herd size larger than 30 cows (OR=2.33 [1.51-3.07]), purchase of animals for breeding (OR= 1.95 [1.13-2.45), and pasture rental practice (R= 1.74 [1.03-2.74]).

Effect of air pollution on diabetes and cardiovascular diseases in São Paulo, Brazil

Type 2 diabetes increases the risk of cardiovascular mortality and these patients, even without previous myocardial infarction, run the risk of fatal coronary heart disease similar to non-diabetic patients surviving myocardial infarction. There is evidence showing that particulate matter air pollution is associated with increases in cardiopulmonary morbidity and mortality. The present study was carried out to evaluate the effect of diabetes mellitus on the association of air pollution with cardiovascular emergency room visits in a tertiary referral hospital in the city of São Paulo. Using a time-series approach, and adopting generalized linear Poisson regression models, we assessed the effect of daily variations in PM10, CO, NO2, SO2, and O3 on the daily number of emergency room visits for cardiovascular diseases in diabetic and non-diabetic patients from 2001 to 2003. A semi-parametric smoother (natural spline) was adopted to control long-term trends, linear term seasonal usage and weather variables. In this period, 45,000 cardiovascular emergency room visits were registered. The observed increase in interquartile range within the 2-day moving average of 8.0 µg/m³ SO2 was associated with 7.0 percent (95 percentCI: 4.0-11.0) and 20.0 percent (95 percentCI: 5.0-44.0) increases in cardiovascular disease emergency room visits by non-diabetic and diabetic groups, respectively. These data indicate that air pollution causes an increase of cardiovascular emergency room visits, and that diabetic patients are extremely susceptible to the adverse effects of air pollution on their health conditions.

Indoor NO2 air pollution and lung function of professional cooks

Studies of cooking-generated NO2 effects are rare in occupational epidemiology. In the present study, we evaluated the lung function of professional cooks exposed to NO2 in hospital kitchens. We performed spirometry in 37 cooks working in four hospital kitchens and estimated the predicted FVC, FEV1 and FEF25-75, based on age, sex, race, weight, and height, according to Knudson standards. NO2 measurements were obtained for 4 consecutive days during 4 different periods at 20-day intervals in each kitchen. Measurements were performed inside and outside the kitchens, simultaneously using Palm diffusion tubes. A time/exposure indicator was defined as representative of the cumulative exposure of each cook. No statistically significant effect of NO2 exposure on FVC was found. Each year of work as a cook corresponded to a decrease in predicted FEV1 of 2.5 percent (P = 0.046) for the group as a whole. When smoking status and asthma were included in the analysis the effect of time/exposure decreased about 10 percent and lost statistical significance. On predicted FEF25-75, a decrease of 3.5 percent (P = 0.035) was observed for the same group and the inclusion of controllers for smoking status and asthma did not affect the effects of time/exposure on pulmonary function parameter. After a 10-year period of work as cooks the participants of the study may present decreases in both predicted FEV1 and FEF25-75 that can reach 20 and 30 percent, respectively. The present study showed small but statistically significant adverse effects of gas stove exposure on the lung function of professional cooks.

Impact of respiratory infections by influenza viruses A and B in pediatrics patients from Federal University of Paraná, Brazil

The objective of the present study was to determine the impact of influenza virus on pediatric hospitalized patients. We retrospectively reviewed records of children with laboratory diagnoses, by cell culture and/or indirect immunofluorescence assay, of influenza virus seen in a period of 6 years. A total of 1,033 samples were analyzed, 45 (4.3 percent) of them being reactive to influenza virus. Thirty-one samples were positive to influenza A virus and 14 to influenza B. The frequency of hospitalization in intensive care and medical emergency was found to be high. Three (8.6 percent) patients died, two of them due to respiratory failure. Low frequency of influenza virus infection was observed in the study. The data suggest the need of more efficient epidemiological surveillance measures in order to obtain reliable information to better assess the impact of the virus on our region and determine the need of preventive measures, such as immunization.

Impact of acute exposure to air pollution on the cardiorespiratory performance of military firemen

The objective of the present study was to determine the impact of acute short-term exposure to air pollution on the cardiorespiratory performance of military fireman living and working in the city of Guarujá, São Paulo, Brazil. Twenty-five healthy non-smoking firemen aged 24 to 45 years had about 1 h of exposure to low and high levels of air pollution. The tests consisted of two phases: phase A, in Bertioga, a town with low levels of air pollution, and phase B, in Cubatão, a polluted town, with a 7-day interval between phases. The volunteers remained in the cities (Bertioga/Cubatão) only for the time required to perform the tests. Cumulative load 10 ± 2 min-long exertion tests were performed on a treadmill, consisting of a 2-min stage at a load of 7 km/h, followed by increasing exertion of 1 km h-1 min-1 until the maximum individual limit. There were statistically significant differences (P < 0.05) in anaerobic threshold (AT) between Cubatão (35.04 ± 4.91 mL kg-1 min-1) and Bertioga (36.98 ± 5.62 mL kg-1 min-1; P = 0.01), in the heart rate at AT (AT HR; Cubatão 152.08 ± 14.86 bpm, Bertioga 157.44 ± 13.64 bpm; P = 0.001), and in percent maximal oxygen consumption at AT (AT percentVO2max; Cubatão 64.56 ± 6.55 percent, Bertioga 67.40 ± 5.35 percent; P = 0.03). However, there were no differences in VO2max, maximal heart rate or velocity at AT (ATvel) observed in firemen between towns. The acute exposure to pollutants in Cubatão, SP, caused a significant reduction in the performance at submaximal levels of physical exertion.

Hemencyrtus herbertii Ashmead (Hymenoptera: Encyrtidae) como parasitóides de dípteros muscóides coletados em Itumbiara, Goiás / Hemencyrtus herbertii Ashmead (Hymenoptera: Encyrtidae) as parasitoid of muscoids dipterous collected in Itumbiara Goiás, Brazil

This study determined the species of hosts of the parasitoid Hemencyrtus herbertii Ashmead (Hymenoptera: Encyrtidae) in human feces, cattle liver and chicken viscera, collected in Itumbiara, Goias. The pupae were obtained by the flotation method. They were individually placed in gelatin capsules until the emergence of adult flies or their parasitoids. The overall prevalence of parasitism was 23.7 percent.

Air pollution and neonatal deaths in São Paulo, Brazil

Air pollution has been associated with health effects on different age groups. The present study was designed to assess the impact of daily changes in air pollutants (NO2, SO2, CO, O3, and particle matter (PM10)) on total number of daily neonatal deaths (those that occur between the first and the 28th days of life) in São Paulo, from January 1998 to December 2000, since adverse outcomes such as neonatal deaths associated with air pollution in Brazil have not been evaluated before. Generalized additive Poisson regression models were used and nonparametric smooth functions (loess) were adopted to control long-term trend, temperature, humidity, and short-term trends. A linear term was used for holidays. The association between air pollutants and neonatal deaths showed a short time lag. Interquartile range increases in PM10 (23.3 æg/m ) and SO2 (9.2 æg/m ) were associated with increases of 4 percent (95 percent CI, 2-6) and 6 percent (95 percent CI, 4-8), respectively. Instead of adopting a two-pollutant model we created an index to represent PM10 and SO2 effects. For an interquartile range increase in the index an increase of 6.3 percent (95 percent CI, 6.1-6.5) in neonatal deaths was observed. These results agree with previous studies performed by our group showing the deleterious effects of air pollutants during the perinatal period. The method reported here represents an alternative approach to analyze the relationship between highly correlated pollutants and public health problems, reinforcing the idea of the synergic effects of air pollutants in public health.

Microhimenópteros parasitóides de dípteros muscóides coletados em diferentes substratos em área de mata em Itumbiara, Goiás / Microhimenopterous parasitoids of muscoids dipterous collected from different substrata in a wood area in Itumbiara, Goias, Brazil

This paper reports the occurrence of parasitoids in pupae of flies (Diptera) collected from several different substrata in Itumbiara, Goiás, Brazil. The pupae were isolated by flotation. They were individually placed into gelatin capsules and kept until the emergency of adult flies or their parasitoids. From March 2001 through April 2002, a total of 684 parasitoids and 830 pupae of flies were collected from humans feces, chicken viscera, fish, and bovine kidney. Brachymeria podagrica were identified in a high number of samples. The prevalence of parasitism was of 82.4 percent.

Parasitoids of flies collected in chicken viscera in Itumbiara, Goiás, Brazil

Este estudo teve como objetivo determinar as espécies de parasitoides associados com moscas coletadas em vísceras de galinha, em Itumbiara, Goiás. Armadilhas contendo vísceras de galinha como isca foram utilizadas para atrair a moscas. As pupas, obtidas pelo método de flutuaçäo, foram colocadas individualmente em cápsulas de gelatina (nº 00) e mantidas em laboratório até a emergência das moscas e/ou dos parasitoides. A prevalência total de parasitismo foi de 20,0 por cento. Brachymeria podagrica, Hemencyrtus sp. (Hymenoptera: Encyrtidae), Nasonia vitripennis (Hymenoptera: Pteromalidae), Paraganaspis egeria (Díaz, Gallardo & Wash) (Hymenoptera: Figitidae), apresentaram prevalência de parasitismo de 8,9 por cento, 10,8 por cento, 0,9 por cento e 0,3 por cento, respectivamente.

Ocorrência de Brachymeria podagrica (Fabricius) (Hymenoptera: Chalcididae) como parasitóide de dípteros coletados em diferentes substratos em Itumbiara, Sul de Goiás, Brasil / Occurrence of Brachymeria podagrica (Fabricius) (Hymenoptera: Chalcididae) as parasitoid of díptera collected in different substrata in Itumbiara, South of Goiás, Brazil

This work aimed to study the prevalence of parasitism of the parasitoid Brachymeria podagrica in Itumbiara, Goiás, using five different substrata: cattle kidneys, human feces, viscera of chicken, fish and cattle liver. The pupae were obtained by the flotation method. They were individually placed in gelatin capsules until the emergency of the adult flies or their parasitoids. The prevalence of parasitism was of 13.8 percent

Aphaereta sp. (Hymenoptera: Braconidae: Alysiinae) as a natural enemy to Peckia chrysostoma (Wiedemann) (Diptera: Sarcophagidae), in Brazil

This paper reports the first occurence of the parasite Aphaereta sp. (Hymenoptera: Braconidae: Alysiinae) which wascollected from Peckia chrysostoma pupae (Diptera: Sarcophagidae) by means of traps containing some fish baits in a wood area close to the Agronomy college (Faculdade of Agronomia) in Itumbiara, Goiás, in the period from March to September, 2001. A total of 362 gregarious specimens of parasitoids from 26 pupae of P. chrysostoma. Aphaereta sp. was collected, with several individuals emerging from the same pupae

Paraganspis egeria Díaz, Gallardo & Walsh (Hymenoptera: Figitidae: Eucoilinae) as potential agent in the biocontrol of muscoid dipterous collected in several substracts in Itumbiara, Goias, Brazil

Este estudo determinou as espécies de hospedeiros do parasitóide Paraganspis egeria (Díaz, Gallardo & Walsh, 1996) (Hymenoptera: Figitidae) em esterco bovino, fezes humanas, rins de bovino, galinha e carcaça de suíno. As pupas foram obtidas pelo método de flutuaçäo. Elas foram colocadas individualmente em cápsulas de gelatina e mantidas até a emergência das moscas e/ou parasitóides. A prevalência total de parasitismo foi de 3,4 por cento

Brachymeria podagrica (Fabricius) (Hymenoptera: Chalcididae) as a parasitoid of Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae): first report in Brazil

Este trabalho relata a primeira ocorrência do parasitóide Brachymeria podagrica (Fabricius, 1787) parasitando estádios imaturos de Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae) no Brasil. Utilizaram-se armadilhas contendo como isca vísceras de galinha. As pupas foram obtidas pelo método de flutuaçäo. Elas foram colocadas individualmente em cápsulas de gelatina e mantidas até a emergência das moscas e/ou dos parasitóides. Foram obtidas 29 pupas de C. albiceps, quatro das quais emergiram parasitóides. A prevalência de parasitismo foi de 13,7 por cento

Ethidium bromide-induced demyelination of the sciatic nerve of adult Wistar rats

Peripheral nerve ultrastructure was assessed after single or multiple local injections of the intercalating dye ethidium bromide. Thirty-four adult Wistar rats of both sexes were divided into five groups and maintained in a controlled environment with rat chow and water ad libitum throughout the experiment. The experimental animals were injected with 1 æl of 0.1 percent ethidium bromide in 0.9 percent saline into the central third of the left sciatic nerve 1 (group 1), 2 (group 2), 4 (group 3), 6 (group 4) or 8 (group 5) times. In groups 2 to 5 the injections were made at 28-day intervals. Control animals received the same amount of 0.9 percent saline. The animals were killed at different times after injection: group 1 at 7 days (2 rats) and 15 days (2 rats); for groups 2, 3, 4 and 5, all rats were killed 10 days after the last injection and the lesions were investigated by light and transmission electron microscopy. In the acute lesions, intoxicated Schwann cells showed a vacuolated cytoplasm and separation of the sheaths from the axon. Myelin sheaths underwent progressive vesiculation and subsequent segmental demyelination. Myelin debris were withdrawn by macrophages and remyelination by Schwann cells was prominent. With the increase in the number of injections collagen fibers also increased in number and progressively enveloped smaller numbers of remyelinated axons composing new fascicles. Wallerian degeneration of fibers apparently not affected by ethidium bromide was more intense in the nerves from groups 4 and 5. The peripheral nerve repairs itself after demyelinating challenges with a profusion of collagen fibers and new fasciculations. This experimental model is valid to mimic recurrent demyelinating neuropathies

Inflammatory response of the spinal cord to multiple episodes of blood-brain barrier disruption and toxic demyelination in Wistar rats

Multiple episodes of blood-brain barrier disruption were induced by sequential intraspinal injections of ethidium bromide. In addition to the barrier disruption, there was toxic demyelination and exposure of myelin components to the immune system. Twenty-seven 3-month-old Wistar rats received 2, 3 or 4 injections of 1 mul of either 0.1 percent ethidium bromide in normal saline (19 rats) or 0.9 percent saline (8 rats) at different levels of the spinal cord. The time intervals between the injections ranged from 28 to 42 days. Ten days after the last injection, all rats were perfused with 2.5 percent glutaraldehyde. The spinal sections were evaluated macroscopically and by light and transmission electron microscopy. All the lesions demonstrated a mononuclear phagocytic infiltrate apparently removing myelin. Lymphocytes were not conspicuos and were found in only 34 percent of the lesions. No perivascular cuffings were detected. In older lesions (38 days and older) they were found only within Virchow-Robin spaces. This result suggests that multiple blood-brain barrier disruptions with demyelination and exposure of myelin components to the immune system were not sufficient to induce an immune-mediated reaction in the central nervous system.