Quantification of Nonproteolytic Clostridium botulinum Spore Loads in Food Materials

We have produced data and developed analysis to build representations for the concentration of spores of nonproteolytic Clostridium botulinum in materials that are used during the manufacture of minimally processed chilled foods in the United Kingdom. Food materials are categorized into homogenous groups which include meat, fish, shellfish, cereals, fresh plant material, dairy liquid, dairy nonliquid, mushroom and fungi, and dried herbs and spices. Models are constructed in a Bayesian framework and represent a combination of information from a literature survey of spore loads from positive-control experiments that establish a detection limit and from dedicated microbiological tests for real food materials. The detection of nonproteolytic C. botulinum employed an optimized protocol that combines selective enrichment culture with multiplex PCR, and the majority of tests on food materials were negative. Posterior beliefs about spore loads center on a concentration range of 1 to 10 spores kg⁻¹. Posterior beliefs for larger spore loads were most significant for dried herbs and spices and were most sensitive to the detailed results from control experiments. Probability distributions for spore loads are represented in a convenient form that can be used for numerical analysis and risk assessments.     

Balancing selected medication costs with total number of daily injections: a preference analysis of GnRH-agonist and antagonist protocols by IVF patients

ABSTRACT: BACKGROUND: During in vitro fertilization (IVF), fertility patients are expected to self-administer many injections as part of this treatment. While newer medications have been developed to substantially reduce the number of these injections, such agents are typically much more expensive. Considering these differences in both cost and number of injections, this study compared patient preferences between GnRH-agonist and GnRH-antagonist based protocols in IVF. METHODS: Data were collected by voluntary, anonymous questionnaire at first consultation appointment. Patient opinion concerning total number of s.c. injections as a function of non-reimbursed patient cost associated with GnRH-agonist [A] and GnRH-antagonist [B] protocols in IVF was studied. RESULTS: Completed questionnaires (n = 71) revealed a mean +/[MINUS SIGN] SD patient age of 34 +/[MINUS SIGN] 4.1 yrs. Most (83.1 %) had no prior IVF experience; 2.8 % reported another medical condition requiring self-administration of subcutaneous medication(s). When out-of-pocket cost for [A] and [B] were identical, preference for [B] was registered by 50.7 % patients. The tendency to favor protocol [B] was weaker among patients with a health occupation. Estimated patient costs for [A] and [B] were $259.82 +/[MINUS SIGN] 11.75 and $654.55 +/[MINUS SIGN] 106.34, respectively (p < 0.005). Measured patient preference for [B] diminished as the cost difference increased. CONCLUSIONS: This investigation found consistently higher non-reimbursed direct medication costs for GnRH-antagonist IVF vs. GnRH-agonist IVF protocols. A conditional preference to minimize downregulation (using GnRH-antagonist) was noted among some, but not all, IVF patient sub-groups. Compared to IVF patients with a health occupation, the preference for GnRH-antagonist was weaker than for other patients. While reducing total number of injections by using GnRH-antagonist is a desirable goal, it appears this advantage is not perceived equally by all IVF patients and its utility is likely discounted heavily by patients when nonreimbursed medication costs reach a critical level.     

Invertebrate communities of subcanopy epiphyte mats subject to commercial moss harvest

Subcanopy epiphytic bryophyte mats are subject to the commercial removal of over 3.7 million kg/year of fresh epiphytic bryophytes (the non-timber forest product of “moss”) from the Coast and Cascade Mountain ranges in the Pacific Northwest of North America. This paper reports on four pilot studies that provide the first characterization of the invertebrates impacted by this harvest. Invertebrates were extracted from harvestable moss mats in both mountain ranges over a period of 4 years. A total of 205 morphospecies and over 143,000 individuals were found in 337 moss mats (totaling less than 25 kg of moss, fresh weight). Invertebrates associated with both canopy and forest floor habitats were recorded. Overall morphospecies composition did not differ between mats harvested from the shrubs vine maple (Acer circinatum) and huckleberry (Vaccinium parvifolium), nor between mats harvested from the stem bases and the branch tips of vine maple. The invertebrate fauna composition was correlated with elevation, stand age, and the vertical distance to water in both the Coast and Cascade Mountain ranges. The lack of differentiation in morphospecies with mat position or host species indicates that these commercial moss harvest practices do not discriminate among taxa, but the overall impacts of harvesting have yet to be determined.     

Secretory proteins in a ciliate cell: Identification of epitopes common to numerous polypeptides

Secretory vesicles of the ciliate Pseudomicrothorax dubius, called trichocysts, are separated into > 40 proteins by two-dimensional gel electrophoresis. The trichocyst, composed of a shaft and four arms, is in a condensed state when docked in the cell cortex, and it elongates into an extended state during exocytosis. Monoclonal antibodies (mAbs) were raised against trichocyst proteins. Their reactivities were analysed: I) on Western blots of extended, isolated trichocysts by immunolabeling; 2) on entire cells and extended trichocysts by indirect immunofluorescent binding assay (IFA); 3) on semi-thin sectioned cells by IFA; and 4) on ultra-thin sections of cells by immunogold labeling. mAb IV 4E5 labels major trichocyst proteins at 15–19, 22 and 24 kDa, pI 4.6?6.6. The epitope recognized by mAb IV 4E5 is common to as many as 30 proteins and suggests a family of proteins with possible sequence homology. By IFA, the shafts of extended trichocysts are labeled. The shafts of condensed trichocysts are labeled on both semi-thin sections in Lowicryl and ultrathin sections. On semi-thin Epon sections, the part of the trichocyst which is labeled is arm-like. mAb VI 2D12 labels three major trichocyst proteins at 31 kDa, pI 5.0?5.4. The arms of extended trichocysts are labeled by IFA, but are only weakly labeled on ultrathin sections. The shaft of extended trichocysts is labeled by IFA, and the shaft of condensed trichocysts is labeled on ultrathin sections.     

New Elements To Consider When Modeling the Hazards Associated with Botulinum Neurotoxin in Food

Botulinum neurotoxins (BoNTs) produced by the anaerobic bacterium Clostridium botulinum are the most potent biological substances known to mankind. BoNTs are the agents responsible for botulism, a rare condition affecting the neuromuscular junction and causing a spectrum of diseases ranging from mild cranial nerve palsies to acute respiratory failure and death. BoNTs are a potential biowarfare threat and a public health hazard, since outbreaks of foodborne botulism are caused by the ingestion of preformed BoNTs in food. Currently, mathematical models relating to the hazards associated with C. botulinum, which are largely empirical, make major contributions to botulinum risk assessment. Evaluated using statistical techniques, these models simulate the response of the bacterium to environmental conditions. Though empirical models have been successfully incorporated into risk assessments to support food safety decision making, this process includes significant uncertainties so that relevant decision making is frequently conservative and inflexible. Progression involves encoding into the models cellular processes at a molecular level, especially the details of the genetic and molecular machinery. This addition drives the connection between biological mechanisms and botulism risk assessment and hazard management strategies. This review brings together elements currently described in the literature that will be useful in building quantitative models of C. botulinum neurotoxin production. Subsequently, it outlines how the established form of modeling could be extended to include these new elements. Ultimately, this can offer further contributions to risk assessments to support food safety decision making.