Anticancer effects of 6-<Emphasis Type="Italic">o</Emphasis>-palmitoyl-ascorbate combined with a capacitive-resistive electric transfer hyperthermic apparatus as compared with ascorbate in relation to ascorbyl radical generation

The aim of the present study is to determine the anti-proliferative activity of 6-o-palmitoyl-l-ascorbic acid (Asc6Palm) that is a lipophilic derivative of l-ascorbic acid (Asc), on human tongue squamous carcinoma HSC-4 cells by combined use of hyperthermia in comparison to Asc. Asc6Palm or Asc were administered to HSC-4 cells for 1 h, to which hyperthermia at 42 °C was applied for initial 15 min. After further 1–72 h incubation at 37 °C, cell proliferation was determined with Crystal Violet staining. Ascorbyl radical (AscR) in HSC-4 cell suspension was measured by electron spin resonance (ESR), and cell morphology was observed with scanning electron microscopy (SEM). At 37 °C, 4 mM Asc or 0.35 mM Asc6Palm were enough to suppress proliferation of HSC-4 cells. By combined use of hyperthermia at 42 °C, cell proliferation was decreased when compared to 37 °C. After Asc of 4 mM was incubated with HSC-4 cell suspensions at 37 °C or 42 °C for 0–180 min, the signal intensity of ascorbyl radical (AscR) by ESR was not different regardless of the presence or absence of cells at 37 °C, whereas AscR signal was enlarged in the presence of HSC-4 cells at 42 °C. It was suggested that oxidation of Asc occurred rapidly in HSC-4 cells by hyperthermia, and thereby enhanced the anti-proliferative activity. By SEM observation, the surface of HSC-4 cells treated with Asc6Palm revealed distinct morphological changes. Thus, the combined regimen of Asc6Palm and hyperthermia is expected to exert a marked antitumor activity.     

Sesquiterpene pyridine alkaloids from Hippocratea excelsa

Nineteen sesquiterpene pyridine alkaloids including 17 new compounds have been isolated from the 70% aq. EtOH extract of stem barks of Hippocratea excelsa. The structures of these compounds were elucidated by various spectroscopic means.     

Dopamine beta-hydroxylase like immunoreactive cells in the frog taste disc

We immunohistochemically examined the existence of dopamine beta-hydroxylase (DBH), a noradrenalin (NA)-synthesizing enzyme from dopamine, in the taste disc of frog, Rana catesbeiana. DBH-like immunoreactive cells were located in the intermediate layer in the taste disc; the cells showed an apical process reaching the surface of the disc and one or several basal processes. Cells with a thick apical process and those with a thin apical process were both immunoreactive: these cells corresponded to type II and III receptor cells of the frog taste disc. Immunoreactive granules were observed in the cytoplasm of those cells. In the frog taste disc, only type III cells are reported to have afferent synapses with the nerve via basal processes but those basal processes have not been reported in type II cells. In the present study, we found that type II-like cells possessed a long basal process extending toward the basal lamina. Mucous (type Ia) cells, wing (type Ib) cells, and glia-like sustentacular (type Ic) cells were all immunohistochemically unreactive. The present observations support the argument that NA (or adrenalin) may work as a chemical transmitter in the frog taste organ.     

Assessment of prion inactivation by combined use of Bacillus-derived protease and SDS

Prions, infectious agents causing transmissible spongiform encephalopathy, retain infectivity even after undergoing routine sterilization processes. We found that MSK103 protease, identified in our previous study, effectively reduces infectivity and the level of misfolded isoform of the prion protein in scrapie-infected brain homogenates in the presence of SDS. The treatment therefore can be applied to the decontamination of thermolabile instruments.     

Immunoassay using microfluid filters constructed by deep X-ray lithography

Microfluid filters were fabricated, which possessed 2,100 cylindrical through-bores (psi 40 microm) in 200 microm-thickness polymethylmethacrylate (PMMA) sheets (psi 3 mm), by deep X-ray lithography using synchrotron radiation. To evaluate the microfluid filters as a device for an immunoassay, we bound the goat anti-mouse immunoglobulin G (IgG) antibody to the surface of the filters, and set the filters between reaction vessels stacked vertically in a microreactor. An enzyme-linked immunosorbent assay (ELISA) of mouse IgG using the goat anti-mouse IgG/horseradish-peroxidase (HRP) conjugate indicated that mouse IgG could be quantitatively detected in the range of 0-100 ng/ml, demonstrating the applicability of vertical microfluidic operation to the immunoassay.     

Electroconductive materials as biomimetic platforms for tissue regeneration

In many diseases, tissue regeneration is compromised and/or insufficient to restore tissue/organ function. Therefore, novel regenerative therapies are being developed to enhance resident and transplanted cell proliferation and functional differentiation. Numerous biomaterials engineered to include nanocomponents have emerged as promising candidates to fulfil the need of mimicking the properties of the healthy extracellular matrix. This is particularly important for tissues that require electroconductive support to achieve optimal cellular function, such as muscles and neurons. In this review, we summarize and discuss the current state-of-the-art for electroconductive materials in tissue regeneration, with particular emphasis on materials containing nanocomponents.     

Chk1 is activated transiently and targets Cdc25A for degradation at the Xenopus midblastula transition

In Xenopus embryos, cell cycle elongation and degradation of Cdc25A (a Cdk2 Tyr15 phosphatase) occur naturally at the midblastula transition (MBT), at which time a physiological DNA replication checkpoint is thought to be activated by the exponentially increased nucleo-cytoplasmic ratio. Here we show that the checkpoint kinase Chk1, but not Cds1 (Chk2), is activated transiently at the MBT in a maternal/zygotic gene product-regulated manner and is essential for cell cycle elongation and Cdc25A degradation at this transition. A constitutively active form of Chk1 can phosphorylate Cdc25A in vitro and can target it rapidly for degradation in pre-MBT embryos. Intriguingly, for this degradation, however, Cdc25A also requires a prior Chk1-independent phosphorylation at Ser73. Ectopically expressed human Cdc25A can be degraded in the same way as Xenopus Cdc25A. Finally, Cdc25A degradation at the MBT is a prerequisite for cell viability at later stages. Thus, the physiological replication checkpoint is activated transiently at the MBT by developmental cues, and activated Chk1, only together with an unknown kinase, targets Cdc25A for degradation to ensure later development.     

IRBIT: A regulator of ion channels and ion transporters

IRBIT (also called AHCYL1) was originally identified as a binding protein of the intracellular Ca^2 + channel inositol 1,4,5-trisphosphate (IP₃) receptor and functions as an inhibitory regulator of this receptor. Unexpectedly, many functions have subsequently been identified for IRBIT including the activation of multiple ion channels and ion transporters, such as the Na⁺/HCO₃⁻ co-transporter NBCe1-B, the Na⁺/H⁺ exchanger NHE3, the Cl⁻ channel cystic fibrosis transmembrane conductance regulator (CFTR), and the Cl⁻/HCO₃⁻ exchanger Slc26a6. The characteristic serine-rich region in IRBIT plays a critical role in the functions of this protein. In this review, we describe the evolution, domain structure, expression pattern, and physiological roles of IRBIT and discuss the potential molecular mechanisms underlying the coordinated regulation of these diverse ion channels/transporters through IRBIT. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.