Internalization of a novel,huge lectin from <Emphasis Type="Italic">Ibacus novemdentatus</Emphasis> (slipper lobster) induces apoptosis of mammalian cancer cells

An N-acetyl sugar-binding lectin (termed iNoL) displaying cytotoxic activity against human cancer cells was isolated from the slipper lobster Ibacus novemdentatus (family Scyllaridae). iNoL recognized monosaccharides containing N-acetyl group, and glycoproteins (e.g., BSM) containing oligosaccharides with N-acetyl sugar. iNoL was composed of five subunits (330, 260, 200, 140, and 30 kDa), which in turn consisted of 70-, 40-, and 30-kDa polypeptides held together by disulfide bonds. Electron microscopic observations and gel permeation chromatography indicated that iNoL was a huge (500-kDa) molecule and had a polygonal structure under physiological conditions. iNoL displayed cytotoxic (apoptotic) effects against human cancer cell lines MCF7 and T47D (breast), HeLa (ovarian), and Caco2 (colonic), through incorporation (internalization) into cells. The lectin was transported into lysosomes via endosomes. Its cytotoxic effect and incorporation into cells were inhibited by the co-presence of N-acetyl-D-mannosamine (ManNAc). Treatment of HeLa cells with iNoL resulted in DNA fragmentation and chromatin condensation, through activation of caspase-9 and ?3. In summary, the novel crustacean lectin iNoL is incorporated into mammalian cancer cells through glycoconjugate interaction, and has cytotoxic (apoptotic) effects.     

Differential usage of COX-1 and COX-2 in prostaglandin production by mast cells and basophils

Basophils have been erroneously considered as minor relatives of mast cells, due to some phenotypic similarity between them. While recent studies have revealed non-redundant roles for basophils in various immune responses, basophil-derived effector molecules, including lipid mediators, remain poorly characterized, compared to mast cell-derived ones. Here we analyzed and compared eicosanoids produced by mouse basophils and mast cells when stimulated with IgE plus allergens. The production of 5-LOX metabolites such as LTB4 and 5-HETE was detected as early as 0.5 h post-stimulation in both cell types, even though their amounts were much smaller in basophils than in mast cells. In contrast, basophils and mast cells showed distinct time course in the production of COX metabolites, including PGD2, PGE2 and 11-HETE. Their production by mast cells was detected at both 0.5 and 6 h post-stimulation while that by basophils was detectable only at 6 h. Of note, mast cells showed 8–9 times higher levels of COX-1 than did basophils at the resting status. In contrast to unaltered COX-1 expression with or without stimulation, COX-2 expression was up-regulated in both cell types upon activation. Importantly, when activated, basophils expressed 4–5 times higher levels of COX-2 than did mast cells. In accordance with these findings, the late-phase production of the COX metabolites by basophils was completely ablated by COX-2 inhibitor whereas the early-phase production by mast cells was blocked by COX-1 but not COX-2 inhibitor. Thus, the production of COX metabolites is differentially regulated by COX-1 and COX-2 in basophils and mast cells.     

Application of positron emission tomography to neuroimaging in sports sciences

To investigate exercise-induced regional metabolic and perfusion changes in the human brain, various methods are available, such as positron emission tomography (PET), functional magnetic resonance imaging (fMRI), near-infrared spectroscopy (NIRS) and electroencephalography (EEG). In this paper, details of methods of metabolic measurement using PET, [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG) and [¹⁵O]radio-labelled water ([¹⁵O]H₂O) will be explained.Functional neuroimaging in the field of neuroscience was started in the 1970s using an autoradiography technique on experimental animals. The first human functional neuroimaging exercise study was conducted in 1987 using a rough measurement system known as ¹³³Xe inhalation. Although the data was useful, more detailed and exact functional neuroimaging, especially with respect to spatial resolution, was achieved by positron emission tomography. Early studies measured the cerebral blood flow changes during exercise. Recently, PET was made more applicable to exercise physiology and psychology by the use of the tracer [¹⁸F]FDG. This technique allowed subjects to be scanned after an exercise task is completed but still obtain data from the exercise itself, which is similar to autoradiography studies.In this report, methodological information is provided with respect to the recommended protocol design, the selection of the scanning mode, how to evaluate the cerebral glucose metabolism and how to interpret the regional brain activity using voxel-by-voxel analysis and regions of interest techniques (ROI).Considering the important role of exercise in health promotion, further efforts in this line of research should be encouraged in order to better understand health behavior. Although the number of research papers is still limited, recent work has indicated that the [¹⁸F]FDG-PET technique is a useful tool to understand brain activity during exercise.     

Adsorption characteristics of P(3HB) depolymerase as evaluated by surface plasmon resonance and atomic force microscopy

Molecular recognition of poly[(R)-3-hydroxybutyrate] (P(3HB)) depolymerase from Ralstonia pickettii T1 to the surfaces of biodegradable aliphatic polyesters such as P(3HB) and poly(L-lactic acid) (PLLA) was examined from the viewpoints of kinetics and dynamics. To determine the kinetic parameters on the interaction between the substrate-binding domain (SBD) of P(3HB) depolymerase and various polymer substrates with different chemical structures, surface plasmon resonance (SPR) measurements were performed. On the other hand, using an atomic force microscopic (AFM) cantilever tip functionalized with the SBD of P(3HB) depolymerase, the mechanical parameters such as unbinding force to the polymer surfaces were measured. Both the SPR and AFM measurements showed that the SBD has a high affinity to P(3HB) and PLLA. From the results of kinetics and dynamics, the energy potential landscape of SBD-polymer interaction was disclosed on the basis of a phenomenological model, and the mechanism of the interaction was discussed.     

A method for the synthesis of an oseltamivir PET tracer

A protocol applicable for the synthesis of an oseltamivir positron emission tomography (PET) tracer was developed. Acetylation of amine 3 with CH(3)COCl, followed by deprotection and aqueous workup, produced oseltamivir 4 from 3 within 10 min. The obtained 4 was sufficiently pure for PET studies. This method can be extended to PET tracer synthesis using CH(3)(11)COCl.     

Effect of contingent auditory stimuli on concurrent schedule performance: an alternative punisher to electric shock

This study explored whether load auditory stimuli could be used as functional punishing stimuli in place of electric shock. Three experiments examined the effect of a loud auditory stimulus on rats’ responding maintained by a concurrent reinforcement schedule. In Experiment 1, overall response rate decreased when a concurrent 1.5 s tone presentation schedule was superimposed on the concurrent variable interval (VI) 180-s, VI 180-s reinforcement schedule. On the contrary, response rate increased when a click presentation schedule was added. In Experiment 2, the extent of the response suppression with a 1.5 s tone presentation varied as a function of the frequency of the reinforcement schedule maintaining responses; the leaner the schedule employed, the greater the response suppression. In Experiment 3, response suppression was observed to be inversely related to the duration of the tone; response facilitation was observed when a 3.0-s tone was used. In Experiments 1 and 2, a preference shift towards the alternative with richer reinforcement was observed when the tone schedule was added. In contrast, the preference shifted towards the leaner alternative when the click or longer duration stimulus was used. These results imply that both the type and duration of a loud auditory stimulus, as well as the reinforcement schedule maintaining responses, have a critical role in determining the effect of the stimuli on responding. They also suggest that a loud auditory stimulus can be used as a positive punisher in a choice situation for rats, when the duration of the tone is brief, and the reinforcement schedule maintaining responses is lean.