Human neurocysticercosis: rightward hemisphere asymmetry in the cerebral distribution of a single cysticercus.

The distribution of single cysticerci between cerebral hemispheres was studied in 227 adult cases of calcified and vesicular neurocysticercosis (NC). A rightward lateralization of calcified cysticerci was significant only in women, whereas vesicular cysticerci were equally distributed in both hemispheres. Factors related with the differences in the inflammatory response and in the regional cerebral blood flow between genders could be involved.

Dose-dependent DNA ruptures induced by the procarcinogen dimethylnitrosamine on primary rat liver cultures.

The effect of certain procarcinogens, among which demethylnitrosamine (DMN) is included, has been difficult to detect in several short-term assays. An alternative system, in which DMN effects could be easily quantitated, might be useful in studies of chemical carcinogenesis and environmental contamination. To develop such a system, we tested the possibility of measuring the amount of breakage produced by DMN on radiolabeled DNA of primary liver cultures. Rat liver cells were isolated 20 to 24 hr after partial hepatectomy, cultured, and pulse labeled in vitro with [3H]thymidine. Radioactively labeled cultures were treated with DMN or with the direct carcinogen N-methyl-N'-nitro-N-nitrosoguanidine and then lysed directly onto alkaline sucrose gradients. DMN and N-methyl-N'-nitro-N-nitrosoguanidine caused a dose-dependent reduction in the molecular weight of DNA, N-methyl-N'-nitro-N-nitrosoguanidine being approximately 1000 times more potent than DMN. DNA breaks appeared to be carcinogen specific and not due to cell death since treatment with high doses of cycloheximide, a noncarcinogenic hepatotoxic, was without significant effect. Our data indicate that detection of DNA breaks constitutes a more sensitive assay of DMN effects than does unscheduled DNA synthesis in primary liver cultures. Therefore, it could be useful to extend our work to determine the general applicability of quantitation of DNA breaks in liver cells as a short-term assay for the identification of possible carcinogens and procarcinogens.

Síndrome intermedio en intoxicación por organofosforados. Serie de casos / Intermediate syndrome in organogosphate poisoning. Case study

Se estima por parte de la Organización Mundial de la Salud, que se presentan alrededor de tres millones de casos asociados a intoxicaciones por plaguicidas. Los plaguicidas se clasifican de acuerdo al grado de toxicidad, medida a través de la dosis letal 50. Los plaguicidas organofosforados son potentes inhibidores de la colinesterasa capaces de causar una toxicidad colinérgica grave tras la exposición cutánea, la inhalación o la ingestión. Los compuestos organofosforados causan múltiples cuadros clínicos, así como manifestaciones de neurotoxicidad a corto y largo plazo. Sin embargo, no se comprende bien la gran variabilidad en la toxicidad y la respuesta al tratamiento entre los agentes organofosforados. En este artículo se revisan tres escenarios clínicos a los cuales nos podremos encontrar con pacientes expuestos a organofosforados, con énfasis en la presentación clínica, tiempo de evolución, medición de la colinesterasa eritrociaria y del tratamiento médico. Se concluye en esta serie de casos que la trascendencia radica, en la diferencia evolutiva de los pacientes ante el manejo, es importante recomendar como parte del tratamiento integral la administración de difenhidramina. (AU)

The World Health Organization estimates around three million cases related to pesticides. Pesticides are classified according to their toxicity which is measured by the lethal dose 50. The pesticides organophosphates are potent cholinesterase inhibitors capable of causing severe cholinergic toxicity following cutaneous exposure, inhalation, or ingestion. Toxicity from organophosphorus agents presents with manifestations of cholinergic excess, and cause neurotoxic effects in humans. However, the great variability in toxicity and treatment response among organophosphorus agents, is not well understood. This article reviews three clinical settings in which the patients were exposed to organophosphates, focusing in variability in toxicity, clinical presentation, direct measurement of erythrocyte cholinesterase, and possibilities for medical treatment. It is concluded in these series that transcendence lies within the evolutive difference from the patients through treatment, it is important to recommend diphenhydramine as part of the comprehensive treatment. (AU)

Intranasal, rectal and intraperitoneal immunization with protoxin Cry1Ac from Bacillus thuringiensis induces compartmentalized serum, intestinal, vaginal and pulmonary immune responses in Balb/c mice.

Recently we discovered that the Cry1Ac protoxin of Bacillus thuringiensis administered to Balb/c mice intraperitoneally (i.p.) or intragastrically is a systemic and intestinal immunogen as potent as cholera toxin. To further characterize the mucosal immunogenicity of Cry1Ac we additionally tried the intranasal (i.n.) and rectal routes and used enzyme-linked immunoassays to determine anti-Cry1Ac antibody responses in the serum as well as in vaginal and tracheobronchial washes and in the fluids of the large and the small intestine. Immunization by the i.p., i.n. and rectal routes induced IgM, IgG and IgA antibodies in all the mucosal surfaces analyzed, but the magnitude and predominant isotype of each response depended on the route used and the mucosal site analyzed. These data extend our findings on the striking mucosal immunogencity of Cry1Ac and provide additional evidence on the compartmentalization of the mucosal immune system.

Norepinephrine, epinephrine and MHPG levels in chick brain development.

In this study we determined the norepinephrine (NE), epinephrine and methoxy-hydroxy-phenyl-glycol (MHPG) levels in dissected chick telencephalon, diencephalon/mesencephalon and cerebellum in a number of stages from the late embryonic period (E16, E17, E18 and E19) and post-hatching period (P1, P2, P3, P4, P5, P15 and P30) using HPLC coupled with a coulometric detection system. A mobile phase which permits the detection of NE, epinephrine and MHPG simultaneously is also described. During development, NE levels increase dramatically after hatching in all brain structures studied and are not correlated in the same period with an increase in the MHPG/NE ratio. The values obtained for epinephrine and MHPG were significantly lower than the NE values in all the structures and stages studied. Our results support the notion of a specific role for NE during the first days after hatching.

Is there a cholinergic circadian rhythm throughout the oestrous cycle related to ovulation in the rat?

Rats with a 4-day oestrous cycle were given a single dose of atropine (100, 300, 500 or 700 mg/kg body wt) at 13.00 h on the days of oestrus, dioestrus 1, dioestrus 2 or pro-oestrus and were autopsied on the next expected day of oestrus. The doses of atropine (in mg/kg body wt) necessary to block ovulation during the cycle were 300 at oestrus, 100 at dioestrus 1 or 2 and 700 at pro-oestrus. A single dose of atropine (100 mg/kg) at oestrus, dioestrus 1 or dioestrus 2 was given at 09.00, 13.00, 17.00 or 21.00 h, autopsy again being performed on the next expected day of oestrus. The ability of atropine to block ovulation appeared to have a circadian rhythm, with a maximum blockade at 13.00 h on dioestrus 1 and dioestrus 2 and a minimum at 21.00 h on the same days. Hormone replacement (human chorionic gonadotrophin at oestrus, dioestrus 1 or 2, oestradiol benzoate at dioestrus 2 or progesterone at pro-oestrus) re-established normal ovulation in rats whose ovulation was blocked with atropine (100 mg/kg) on dioestrus 1 at 13.00 h. When ovulation was blocked with atropine but no hormone replacement had been given, rats ovulated 24 h after the next expected day of oestrus. Results obtained in these experiments suggest the existence of a circadian rhythm of gonadotrophin secretion throughout the oestrous cycle and a close relationship between that rhythm and the cholinergic system.

Cytopathogenicity of Entamoeba histolytica: hemolytic activity of trophozoite homogenates.

In in vitro assays the hemolytic activity of total homogenates of trophozoites of seven strains of amebae were tested for specificity and potency against the erythrocytes of eight mammalian species. The species of Entamoeba included in the tests were E. histolytica, E. invadens, E. moshkovskii, and the Laredo type of E. histolytica. The hemolytic activity was found to be dose-dependent and strain-specific, with E. histolytica being generally the species having the highest hemolytic potency.

Pre- and post-hatching developmental changes in beta-adrenoceptor subtypes in chick brain.

This study used [3H]CGP 12177 as a radioligand to determine the beta1 and beta2-adrenoceptor changes from the pre-hatching E17 stage, where the beta2 subtype is first detected, to the post-hatching P30 stage. While beta1-adrenoceptors were found to be present from E18 and were limited to cerebellum and hyperstriatum in all stages studied, beta2-adrenoceptors showed a wider distribution throughout the brain. In most of the structures analysed both beta1- and beta2-adrenoceptor binding values reached a maximum in the P2 stage, followed by a decrease over the following days. A second increase in both subtypes was detected again in the P15 and P30 stages. These results support the notion of a specific role for beta-adrenoceptors in neural plasticity in the first week after hatching and suggest that the beta2 subtype is the main adrenoceptor in chick brain throughout its development.

A comparative study of the beta-adrenoceptors in higher song nuclei of birds.

The present study analyses the presence of beta-adrenoceptors in the main telencephalic song nuclei of the goldfinch and parakeet, species belonging to the two most important groups of birds that reproduce learned songs: oscine songbirds and parrots, respectively. Brains of both species sectioned at appropriate levels were used to perform autoradiographic saturation studies using [3H]CGP 12177 as a radioligand. The results show similar K(D)values for both species (0.1-0.3 nM) and striking differences in Bmax. Thus, beta-adrenoceptors are abundant in the telencephalic vocal control nuclei of the parakeet but not of the goldfinch. The predominance of the beta2 subtype in the song nuclei of both species is also confirmed. We conclude that these receptors could be involved in functions unique to the parakeet and therefore may contribute to the greater flexibility of the vocal system of this species. Our findings also support the possible involvement of beta-adrenoceptors in the evolution of the avian brain.

A comparative study of the beta-adrenoceptors in higher visual centres of birds.

This report describes the distribution of beta-adrenergic receptors in the telencephalic visual nuclei of chick, duck, pigeon, parakeet and goldfinch using [3H]CGP 12177 (4-3-t-butylamino-2-hydroxypropoxy-[5,7(3)H] benzimidazol-2-one) as a radioligand. The results reveal a predominance of the beta2-adrenoceptor subtype in all the species studied and that this subtype fits the pharmacological profile described for mammals. It is also demonstrated that the autoradiographic interspecific differences described in previous studies are due to changes in Bmax, while KD values remain in a similar range (0.1-0.6 nM). The distribution of beta-adrenoceptors was fairly similar in the areas of the visual Wulst of all five species studied while striking differences were found in the ectostriatum, the higher centre of the tectofugal pathway. Our findings support a role for ectostriatal beta-adrenoceptors in the visual adaptation and evolution of birds.

Autoradiographic characterisation of beta-adrenoceptors in chick brain using [3H]CGP 12177.

An autoradiographic method for labelling beta(1)- and beta(2)-adrenoceptors using [3H]CGP 12177 as a radioligand is described as well as the procedure for an autoradiographic saturation kinetic study. The method afforded higher quality autoradiographs as well as an improvement in the tissue preservation when assayed in birds and chick embryos. The results confirmed the K(d) values previously reported for membrane homogenate binding. The use of different radioligands to characterise beta-adrenoceptors, the higher B(max) values found with autoradiography than those obtained by the membrane homogenate binding method and the typical errors in quantifying autoradiography are discussed. It is concluded that the method described here considerably improves autoradiographic beta-adrenergic characterisation.

DNA breaks induced by micromolar concentrations of dimethylnitrosamine in liver primary cell cultures from untreated and phenobarbital treated rats.

Direct genotoxic effects of the alkylating agent dimethylnitrosamine (DMN) have been difficult to detect in several short-term tests. We simplified our method to detect DNA breaks induced by DMN in rat liver primary cell cultures, and increased its sensitivity about 150 times by changing the conditions of ultracentrifugation and exposure to DMN. Additionally we increased 4 times the sensitivity of the improved assay by isolating hepatocytes from rats treated with phenobarbital (PB). Treatment for 24 h with 60 microM and 13.5 microM DMN of hepatocytes isolated from untreated and PB-treated rats, respectively, decreased the molecular weight of DNA by 50%. After 24 h exposure to 13.5 microM [14C]DMN, hepatocytes from PB-treated rats incorporated 3 times more radioactivity into trichloroacetic acid precipitable material than hepatocytes from untreated rats. Also PB-treatment increased remarkably cytotoxic effects of DMN while it did not modify the cytotoxicity nor the genotoxicity of the direct-acting alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine. These results show that DMN is more genotoxic for hepatocytes from PB-treated rats, and suggest that the enhanced genotoxicity is probably due to an augmented metabolism of DMN by these cultures. Our improved assay of DNA breaks as an indicator of DMN genotoxicity is now as sensitive but faster to perform than hepatocyte-mediated mutagenesis. It could be used to explore genotoxic effects of other alkylating agents and the action of microsomal enzyme modifiers on genotoxicity.

Different antiamebic antibody isotype patterns in the large and small intestine after local and systemic immunization of mice with glutaraldehyde fixed Entamoeba histolytica trophozoites.

We have determined the major immunoglobulin isotypes (IgG, IgA, IgM) of antiamebic antibodies induced in the serum and in the large and small intestine after local (oral and rectal) or systemic (intraperitoneal and intramuscular) immunization of mice with glutaraldehyde-fixed Entamoeba histolytica trophozoites (GFT). IgA predominated in the small intestine after immunization through all routes, whereas in the large intestine similar antibody levels of the major isotypes were induced by rectal, intraperitoneal and intramuscular immunization. The intramuscular route elicited intestinal responses lower than those induced by the rectal and intraperitoneal routes, but higher than the slight IgA antibody increase observed after oral immunization. The differences in antiamebic antibody response patterns at the large and small intestine suggest that there are different mucosal effector compartments. They also indicate that isotype analysis of mucosal antibodies from the sites where an infectious agent resides is needed to evaluate whether a vaccine candidate induces responses of higher protective value in the appropriate site, and that the study of antibody responses must not be limited to sampling the serum or mucosal sites distant to the relevant one.

Intragastric and intraperitoneal administration of Cry1Ac protoxin from Bacillus thuringiensis induces systemic and mucosal antibody responses in mice.

The spore-forming soil bacterium Bacillus thuringiensis produces parasporal inclusion bodies composed by delta-endotoxins also known as Cry proteins, whose resistance to proteolysis, stability in highly alkaline pH and innocuity to vertebrates make them an interesting candidate to carrier of relevant epitopes in vaccines. The purpose of this study was to determine the mucosal and systemic immunogenicity in mice of Cry1Ac protoxin from B. thuringiensis HD73. Crystalline and soluble forms of the protoxin were administered by intraperitoneal or intragastric route and anti-Cry1Ac antibodies of the major isotypes were determined in serum and intestinal fluids. The two forms of Cry1Ac protoxin administered by intraperitoneal route induced a high systemic antibody response, however, only soluble Cry1Ac induced a mucosal response via intragastric. Serum antibody levels were higher than those induced by cholera toxin. Systemic immune responses were attained with doses of soluble Cry1Ac ranging from 0.1 to 100 microg by both routes, and the maximal effect was obtained with the highest doses. High anti-Cry1Ac IgG antibody levels were detected in the large and small intestine fluids from mice receiving the antigen via i.p. These data indicate that Cry1Ac is a potent systemic and mucosal immunogen.

Immediate autoproteolysis and new proteinases in Entamoeba invadens and Entamoeba moshkovskii trophozoites.

We have examined the sodium dodecyl sulfate (SDS)-induced autoproteolysis of E. invadens (PZ and IP101) and E. moshkovskii (FIC and Laredo) trophozoite lysates. Heat-treated lysates containing parahydroxy-mercuribenzoate (pHMB) of all four strains had undegraded protein patterns. Unheated pHMB-lacking lysates of PZ had two (99 and 90 kDa) and IP101 lysates had three (45, 99, 90 kDa) major proteins, whereas FIC and Laredo lysates had only one (90 kDa). Heat-treatment changed the remaining proteins to smaller ones: 37 in PZ and IP101, 33 and 37 kDa in FIC and Laredo. Unheated lysates run on gelatin-containing "substrate" gels had gelatinases whose sizes were higher in lysates containing pHMB and allowed us to detect a 200 kDa gelatinase in E. invadens strains. Our results indicate that SDS induces immediate autoproteolysis by CPs in non-histolytica trophozoites, whose proteinases appear to be processed by self-digestion, and Entamoeba proteinases vary considerably under the various conditions used to obtain and characterize them.

Electrophysiology and immunity of the mucosa in intestinal infections.

We present here some of the major concepts and approaches to study the electrophysiology of the intestinal mucosa, and review the pathophysiology of intestinal infections caused by enteropathogenic bacteria, protozoa--especially our own work on experimental amebiasis using intestinal preparations mounted in the Ussing chamber--and nematodes, and finally discuss briefly the immunophysiology of the intestinal mucosa.

Model of intestinal amebiasis: structural and functional lesions to the rabbit colon mucosa by Entamoeba histolytica lysates.

Although the events occurring during the initial interaction of E. histolytica trophozoites with the mucosa of the large intestine probably determine the invasion by the parasites, an appropriate experimental model does not exist. To develop such a model we used full-thickness rabbit colon preparations (0.28 cm2) mounted in Ussing-type chambers. Untreated preparations had electrophysiological properties (potential difference, short-circuit current and electrical resistance) similar in magnitude and duration to those reported for stripped colonic mucosa. Exposure to E. histolytica trophozoite lysates for up to 80 min produced dose-dependent lesions in the colon, consisting of: (a) increased decay rates for potential difference, short-circuit current and transmural resistance, and (b) mucosal lesions involving vacuolation at the bases and shortening of epithelial cells, loss of intercellular junctions, destruction of microvilli, and necrosis of interglandular epithelial zones. The specificity and speed of the electrophysiologic effects and their correlation with the microscopic lesions suggest that this new model will help to understand the initial pathogenic events of intestinal amebiasis.

Variation of proteins and proteinases in Entamoeba histolytica lysates containing a protease inhibitor.

Sodium dodecyl sulfate (SDS)-lysates of E. histolytica trophozoites were analyzed by electrophoresis in simple and gelatin-containing ("substrate") SDS-polyacrylamide gels. In simple gels, boiled lysates with para hydroxymercuribenzoate (pHMB) had a complex pattern of apparently undegraded proteins; boiled lysates without pHMB showed a major 30 kDa and four minor (43, 46, 63 and 117 kDa) proteins, whereas unheated lysates displayed only the 117 kDa protein. Using substrate gels no gelatinases were detected in heated lysates; unheated lysates without pHMB showed a major 30 kDa and three minor (33, 46 and 68 kDa) gelatinases, whereas those with pHMB presented a major 56 kDa and two minor (70 and 105 kDa) gelatinases. Three caseinase peaks were separated by Sephadex G-75 chromatography from unheated lysates: peak I contained 46, 56 and 117 kDa pHMB-sensitive gelatinases and peaks II and III contained smaller pHMB-resistant caseinases. We conclude that proteins remaining in lysates after SDS-induced proteolysis appear to be mainly proteases relatively resistant to self-digestion whose type and amount changes with the conditions of lysis and the presence of inhibitors; this is exemplified by the finding of the major gelatinase of lysates with pHMB being larger (56 kDa) than in lysates lacking the inhibitor (30 kDa).

Evidence that the loss of bone mass induced by GnRH agonists is not totally recovered.

There is disagreement as to whether the loss of bone mass induced by GnRH agonists is reversible. In part, the differences of opinion might be attributed to the fact that the influence of weight and seasonal changes on bone mass is often overlooked. Taking into consideration weight and seasonal changes in bone mass, total (TBBMC) and regional body bone mineral content were measured in 38 women treated with GnRH agonists for 6 months for endometriosis or leiomyomata. Measurements were made at the onset of treatment, at 6 months of treatment and at 6 months after finishing treatment. TBBMC was corrected for body weight. Body weight had increased significantly at 6 months of treatment (P = 0.0175). Regional bone mineral content showed the following: limbs, no changes; head, significantly lower at 12 months than at baseline (P = 0.0036) and at 6 months (P = 0.0343) of therapy; trunk, significantly lower at 6 months (P = 0.0002) compared to baseline, but the values at 1 year were not significantly different from either the baseline or the 6-month values; pelvis, the same pattern of change as in the trunk (P = 0.0349). TBBMC was significantly lower at 6 months of treatment (P < 0.0001) and at 1 year (P = 0.0162). TBBMC adjusted for weight experienced the same changes as unadjusted bone mineral content (P < 0.0001 and P < 0.0009 at 6 months and 1 year, respectively). Our findings indicate that the bone mass lost with GnRH treatment had not been restored 6 months after discontinuing treatment.

Changes in body composition in women treated with gonadotropin-releasing hormone agonists.

OBJECTIVE: The changes that agonists of gonadotropin-releasing hormone (GnRH) produce in mineral bone mass are known, but, as far as we know, those produced by these agents in other body compartments are unknown. METHODS: We studied these changes using dual-energy X-ray absorptiometry in 50 eugonadal women treated with decapeptyl (Triptoreline), 3.75 mg injected intramuscularly, at 28-day intervals for 6 months. RESULTS: There were significant increases in fat content (9.5%, P < 0.0005) and weight (1.3%, P < 0.01), and significant decreases in fat-free mass (-1.9%, P < 0.0001) and water content (-1.8%, P < 0.0002). Bone mass was lost in the axial skeleton (-3.6%, P < 0.0001) but not in the peripheral skeleton. CONCLUSIONS: The changes induced in body composition by the GnRH agonists are similar to those of natural menopause.