Mucosal mast cell secretion processes imaged using three-photon microscopy of 5-hydroxytryptamine autofluorescence

The secretion process of the mucosal mast cell line RBL-2H3 was imaged using infrared three photon excitation (3PE) of serotonin (5-hydroxytryptamine, 5-HT) autofluorescence, a measurement previously difficult because of the technical intractability of deep UV optics. Images of prestimulation 5-HT distributions were analyzed in loaded cell populations (those incubated in a 5-HT-rich medium overnight) and in unloaded populations and were found to be strictly quantifiable by comparison with bulk population high-performance liquid chromatography measurements. Antigenically stimulated cells were observed to characteristically ruffle and spread as granular 5-HT disappeared with no detectable granule movement. Individual cells exhibited highly heterogeneous release kinetics, often with quasi-periodic bursts. Neighboring granule disappearances were correlated, indicative of either spatially localized signaling or granule-granule interactions. In one-half of the granule release events, weak residual fluorescence was visible suggestive of leftover 5-HT still bound to the granule matrix. The terminal stages of secretion (>300 s) consisted primarily of unresolved granules and remainder 5-HT leakage from already released granules.     

Distributions for Key Exposure Factors Controlling the Uptake of Xenobiotic Chemicals by Great Blue Herons (Ardea herodius) through Ingestion of Fish

A variety of exposure factors ultimately control the uptake of xenobiotic chemicals by colonial piscivorous birds, such as herons and egrets. These factors, which include feeding rate for various food sources, feeding territory size, and body weight, are critical to the implementation of models commonly used to predict ecological risks. A critical evaluation of literature on avian behavior, physiology, and ecology was conducted in order to identify those variables that most strongly influence uptake of chemicals by herons and egrets. After developing a database of such exposure factors, we identified each factor's range, central tendency, and distribution. Sufficient information was available to allow the development of statistical distributions for body weight, fraction of diet from fish, prey length, distance to foraging site, and feeding territory size for great blue herons. The five distributions presented in this paper are intended to support probabilistic assessments of potential risks to great blue herons. Distributions of exposure factors for great blue herons have not been previously published. Without such data, application of all but the most simple mechanistic models will require point estimates, most of which will be overly conservative and will not support accurate characterization of actual exposures of herons at hazardous waste sites.     

Comparison of Ribotyping and Repetitive Extragenic Palindromic-PCR for Identification of Fecal Escherichia coli from Humans and Animals

This report compares the performances of two popular genotypic methods used for tracking the sources of fecal pollution in water, ribotyping and repetitive extragenic palindromic-PCR (rep-PCR). The rep-PCR was more accurate, reproducible, and efficient in associating DNA fingerprints of fecal Escherichia coli with human and animal hosts of origin.     

Identification of Fecal Escherichia coli from Humans and Animals by Ribotyping

Fecal pollution of water resources is an environmental problem of increasing importance. Identification of individual host sources of fecal Escherichia coli, such as humans, pets, production animals, and wild animals, is prerequisite to formulation of remediation plans. Ribotyping has been used to distinguish fecal E. coli of human origin from pooled fecal E. coli isolates of nonhuman origin. We have extended application of this technique to distinguishing fecal E. coli ribotype patterns from human and seven individual nonhuman hosts. Classification accuracy was best when the analysis was limited to three host sources. Application of this technique to identification of host sources of fecal coliforms in water could assist in formulation of pollution reduction plans.     

Millipede phylogeny revisited in the light of the enigmatic order Siphoniulida

The discovery of six specimens of the enigmatic order Siphoniulida, including for the first time males, prompted a modern re‐analysis of current phylogenetic schemes for the class Diplopoda derived from traditional morphological and developmental characters. The data matrix was constructed and analysed using paup . The resulting phylogenetic hypotheses corroborated the longest standing, traditional classification, but also demonstrated clearly that more characters must be included to reach a better resolution. Recent alternative phylogenetic hypotheses and classifications are discussed in the light of the current analysis. The validity of a putative helminthomorph synapomorphy, the location of male gonopods on the 7th body ring, is discussed. Scanning electron microscopy corroborated morphological characters already described for the Siphoniulida: modified anterior legs, an apparently legless 3rd body ring, pyriform head, antennae with clavate setae, and absence of ozopores. The highly modified gonopods of the Siphoniulida are described for the first time; only the anterior legs of the 7th ring are modified into gonopods, the posterior legs of this ring are developed as normal walking legs. The gnathochilarium differs from the Colobognatha and consists of well‐developed stipites with palps, elongated lingual plates with palps and a narrow central sclerite, most likely the mentum. Structures on the epiproct may possibly be spinnerets. Despite the discovery of adult males, the Siphoniulida are still considered Helminthomorpha incertae sedis .     

Determinants of recall and recall bias in studying drug and chemical exposure in pregnancy

Case-control studies on effects of drugs in pregnancy rely heavily on maternal recall. At the Motherisk Program in Toronto we counsel women during early pregnancy on the risk of drug and chemical exposure; subsequently, we follow up the outcome of pregnancy after birth. This cohort has given us an opportunity to assess the magnitude of recall of early pregnancy exposure and determinants likely to affect it in 145 consecutive cases. The mean recall of exposure identity was 62%, while accurate recall of timing of exposure was 37% and of dosage 24%. Exposures that prompted the clinic visit, chronic therapeutic exposures, environmental agents, and known teratogens were recalled significantly better than were other exposures. Accurate report of smoking was significantly higher than of alcohol use (79.4% vs. 59%, respectively, P = .0002). The number of agents consumed by the pregnant woman negatively correlated with her recall; mean recall of 1 agent was 85% vs. only 40% recall of 4 agents. Women greater than or equal to 30 years of age recalled significantly worse (mean +/- SEM, 52 +/- 4%) than women younger than 30 (70 +/- 4%), P = .002) despite a similar mean number of exposures. No difference in mean recall was found between women having normal (n = 112) or adverse pregnancy outcome (n = 33). There was a recall bias in reporting alcohol consumption; postnatally, women with adverse outcome tended to report significantly less than the amount initially reported by them.     

Building on the foundation of daring hypotheses: using the MKK4 metastasis suppressor to develop models of dormancy and metastatic colonization

The identification of a novel metastasis suppressor function for the MAP Kinase Kinase 4 protein established a role for the stress-activated kinases in regulating the growth of disseminated cancer cells. In this review, we describe MKK4's biological mechanism of action and how this information is being used to guide the development of new models to study cancer cell dormancy and metastatic colonization. Specifically, we describe the novel application of microvolume structures, which can be modified to represent characteristics similar to those that cancer cells experience at metastatic sites. Although MKK4 is currently one of many known metastasis suppressors, this field of research started with a single daring hypothesis, which revolutionized our understanding of metastasis, and opened up new areas of exploration for basic research. The combination of our increasing knowledge of metastasis suppressors and such novel technologies provide hope for possible clinical interventions to prevent suffering from the burden of metastatic disease.     

Role of IFN-gamma in lethal and nonlethal malaria in susceptible and resistant murine hosts

IFN-gamma plays an important role in host defense against microbial disease. Here, we studied the role of IFN-gamma in lethal and nonlethal murine malaria. Administration of recombinant murine IFN-gamma resulted in a dose-dependent protection of SW, BALB/cByJ, and CBA/J mice from the lethal variant of Plasmodium yoelii 17x (PyL) but had little effect on the course of the nonlethal variant of this parasite (PyNL). Administration of recombinant IFN-gamma also resulted in the activation of peritoneal macrophages for increased phagocytosis of malaria-infected erythrocytes and release of H2O2, as measured in vitro. The ability of spleen cells from infected mice to produce endogenous IFN-gamma and release H2O2 during the course of malaria was also studied. In BALB/cByJ mice, which are relatively susceptible to PyL and PyNL, there was an initial burst of IFN-gamma only in response to PyNL whereas in CBA/J mice, which are relatively resistant to these parasites, there was an initial burst of IFN-gamma in response to both PyL and PyNL. The kinetics of H2O2 release corresponded to that of IFN-gamma. In all infections, levels of IFN-gamma declined as parasitemia increased; however, nonlethal infections were characterized by a recovery of both IFN-gamma activity and H2O2 release as parasitemia declined. These data suggest that IFN-gamma may play an important role in modulating the course of malaria infections by activating macrophages for both intracellular and extracellular parasite destruction.