Antifreeze proteins: characteristics, occurrence and human exposure.

Antifreeze proteins (AFPs), also known as ice structuring proteins, bind to and influence the growth of ice crystals. Proteins with these characteristics have been identified in fish living in areas susceptible to ice formation and in numerous plants and insects. This review considers the occurrence of AFPs and relates it to the likely intake by human populations, with a view to forming a judgment about their safety in foods. Intake of AFPs in the diet is likely to be substantial in most northerly and temperate regions. Much of this intake is likely to be from edible plants, given their importance in the diet, but in some regions intake from fish will be significant. Inadequate data exist to estimate intakes from plants but estimates of intake of AFP from fish are presented for two countries with very different fish consumption, the USA and Iceland. Typical short-term exposure, for instance a portion of cod may contain up to 196 mg AFGP, while the AFP content of the same weight of ocean pout would be up to 420 mg. Average available fish AFP in the diet is calculated to be around 1-10 mg/day in the USA and 50-500 mg/day in Iceland, but these estimates are subject to considerable uncertainty. As far as can be ascertained, AFPs are consumed with no evidence of adverse health effects, either short- or long-term. Given the structural diversity of AFPs, one firm general conclusion that can be drawn from the history of consumption of AFPs is that their functional characteristics do not impart any toxicologically significant effect, in a way that, for instance, a property such as cholinesterase inhibition would. Furthermore, specifically in the case of fish AFPs where some consumption data are available, it is reasonable to infer a lack of allergenicity from the absence of reports of this effect.     

Diagnosis of chimerism based on blood group determination]

The authors report the results of blood group determinations in a 9-year-old girl in whom two populations of erythrocytes were discovered. The larger population accounting for nearly 80% of erythrocytes contained the antigen A2, the smaller population had the B antigen. Besides that differences were observed in the antigens of Duffy and Lewis systems. In the saliva A and H antigens were revealed. Familial investigations indicated the participation of two gametes of maternal origin (mother--AB, father--O) although no evidence of twin pregnancy was available. The cause of this chimaerism has not been explained.     

Ocular and facial injuries associated with the use of immersion heaters in an inmate population

PURPOSE: To report ocular and facial injuries caused by the use of electric immersion heaters in an inmate population. DESIGN: Prospective observational case series. METHODS: Data were recorded over a six-month period on age, gender, mechanism of injury, examination, and treatment of Dallas County inmates who experienced ophthalmic injuries from immersion heaters and were referred to a tertiary-care center. RESULTS: Eight male inmates were treated for thermal ocular injuries, which occurred within jail cells as a result of cooking explosions from electric immersion heaters, known by inmates as "stingers." All patients had thermal eyelid burns, either first- or second-degree facial burns, and corneal abrasions with corneal edema. Corneal metallic foreign bodies were removed in one patient, and three patients underwent debridement for corneal sloughing. CONCLUSIONS: Immersion heater-related accidents may cause thermal injuries within the inmate population. Physicians evaluating incarcerated patients with ocular trauma should be aware of immersion heaters as a common cause.     

Effect of an experimental proteasome inhibitor on the cytoskeleton, cytosolic protein turnover, and induction in the neuronal cells in vitro

GT-1 murine neuronal cells exposed to an experimental proteasome inhibitor (EPI) for 24h showed increased cell death via a non-apoptotic mechanism, as assessed by TUNEL and DNA fragmentation assays. Immunofluorescence staining demonstrated that EPI induced reorganization and relocation of non-ubiquinated actin microfilaments and microtubules to the perinuclear region in EPI treated cells. Immunohistochemistry analysis also demonstrated that other non-cytoskeletal proteins became ubiquitinated and/or upregulated including ubiquitin and other stress proteins. Perinuclear-centrosomal accumulation of gamma-tubulin and vimentin, key components of aggresomes, was observed in the EPI treated cells. Biochemical analysis indicated that EPI-induced accumulation of ubiquitinated protein aggregates in GT-1 cells was detergent - and mechanical - disruption resistant, a feature of aggresomes. Similar results were observed in GT-1 cells treated with lactacystin, a prototypical proteasome inhibitor, which is structurally dissimilar to EPI indicating a pharmacologic effect. In conclusion, EPI causes cytoskeletal reorganization and accumulation of diverse ubiquitinated and non-ubiquitinated proteins in the perinuclear region and potentially overloads the endoplasmic reticulum-dependent quality control mechanism. These processes acting alone, or in combination, are hypothesized to affect axonal transport or other aspects of cellular homeostasis and thus, represent events potentially relevant to the development of peripheral neuropathy associated with administration of proteasome inhibitors in nonclinical studies.     

The ability of the Comet assay to discriminate between genotoxins and cytotoxins

The Comet assay has been used widely in genetic toxicology,radiation biology and medical and environmental research. Thisassay detects single-strand breaks and alkali-labile sites inDNA and DNA degradation due to necrosis or apoptosis. It mayalso be modified to detect DNA crosslinking. Although a considerablenumber of chemicals have been tested in the assay there aremany aspects of validation to be considered before the methodcould be considered to provide definitive evidence of genotoxicpotential. For example, very few non-genotoxins have been testedto assess specificity of the Comet assay and there has beenonly one reported study which investigated whether the in vitroComet assay is prone to false positive responses due to cytotoxicity.We have investigated the response of the alkaline Comet assayin TK6 human lymphoblastoid cells to cytotoxic damage and genotoxicdamage. Several compounds which are toxic by different mechanismswere tested in the assay. Cycloheximide and trypsin gave a negativecomet response at a highest dose of 5 mg/ml and no toxicitywas observed. Sodium lauryl sulphate and potassium cyanide produceda significant increase in DNA migration at cell survival levelsof     

Prostaglandin E2 receptors of the EP2 and EP4 subtypes regulate activation and differentiation of mouse B lymphocytes to IgE-secreting cells.

Prostaglandin E2 (PGE2) is a potent lipid molecule with complex proinflammatory and immunoregulatory properties. PGE2 can shape the immune response by stimulating the production of IgE antibody by B lymphocytes and the synthesis of T-helper type 2 cytokines [e.g., interleukin (IL)-4, IL-10], while inhibiting production of Th1 cytokines (e.g., interferon-gamma, IL-12). It is unknown what type of receptor binds PGE2 and modulates these responses. Recent analyses in nonhematopoietic cells have identified six PGE2 receptors (EP1, EP2, EP3 alpha, EP3 beta, EP3 gamma, and EP4). This investigation examines quiescent B lymphocytes and reports that these cells express mRNA encoding EP1, EP2, EP3 beta, and EP4 receptors. The immunoregulatory functions of each receptor were investigated using small molecule agonists that preferentially bind EP receptor subtypes. Unlike agonists for EP1 and EP3, agonists that bound EP2 or EP2 and EP4 receptors strongly inhibited expression of class II major histocompatibility complex and CD23 and blocked enlargement of mouse B lymphocytes stimulated with IL-4 and/or lipopolysaccharide. PGE2 promotes differentiation and synergistically enhances IL-4 and lipopolysaccharide-driven B-cell immunoglobulin class switching to IgE. Agonists that bound EP2 or EP2 and EP4 receptors also strongly stimulated class switching to IgE. Experiments employing inhibitors of cAMP metabolism demonstrate that the mechanism by which EP2 and EP4 receptors regulate B lymphocyte activity requires elevation of cAMP. In conclusion, these data suggest that antagonists to EP2 and EP4 receptors will be important for diminishing allergic and IgE-mediated asthmatic responses.