Stictodora lari (Digenea: Heterophyidae): the discovery of the first human infections

Stictodora lari Yamaguti, 1939 (Digenea: Heterophyidae) was originally reported as an avian intestinal parasite and is here reported in humans. The patients were adults, aged 46-69 (2 men and 4 women), who resided in coastal villages in Sachon-gun, Kyongsangnam-do, or Shinan-gun, Chollanam-do. in the Republic of Korea. The worms were recovered after praziquantel treatment and purgation with magnesium salts. A total of 15 S. lari specimens (1-10 per individual) was collected, together with 5 other species of intestinal flukes. The flukes were morphologically characterized by a small body size (0.70-0.86 mm long and 0.27-0.36 mm wide), a ventrogenital sac, and a gonotyl armed with 70-80 spines in the form of a comma or reversed comma lying along their lateral margin. The patients had eaten the raw flesh of mullets and gobies that had been caught in an estuary near their villages. To the best of our knowledge, this is the first record of a human S. lari infection.

Characterization of (1'R,4S,4aR,7S,7aR)-dihydronepetalactol as a semiochemical for lacewings, including Chrysopa spp. and Peyerimhoffina gracilis

The enantiomerically pure diastereoisomers (1R,4S,4aR,7S,7aR)- (1) and (1R,4R,4aR,7S,7aR)-dihydronepetalactol (2) were synthesized diastereoselectively from a renewable resource, (4aS,7S,7aR)-nepetalactone (3), isolated as the main constituent of the essential oil of the catmint plant Nepeta cataria. The stereochemistry of the compounds was determined by NMR spectroscopy and X-ray crystallography, and the compounds were identified, respectively, as neomatatabiol and isoneomatatabiol, natural products from Actinidia polygama, for which the lactol stereochemistry was previously incompletely defined. Compound 1 was found to catch significant numbers of three species of lacewing in the field: in Korea. Chrysopa cognata, and in the United Kingdom, Nineta vittata and most notably Peverimhoffina gracilis. All species caught in significant numbers were found more frequently in traps releasing 1 than 2, while more C. cognata, C. formosa, and C. phyllochroma were found in traps releasing (1R,4aS,7S,7aR)-nepetalactol (4). The catch of P. gracilis with 1 is of particular interest as this lacewing has only recently been recorded in the United Kingdom. Where sexed, the lacewings of all species trapped were found to be male, implying a possible pheromonal role for these or structurally related compounds.

Synthesis of 188 Re-labelled long chain alkyl diaminedithiol for therapy of liver cancer

Radioisotope-labelled lipiodol has been used in the therapy of liver cancer. Recently a lipiodol solution of 188Re-labelled diaminedithiol (DD) has been reported to show a high uptake in the liver cancer. We synthesized long-chain alkyl DD derivatives to improve their uptake and retention in tissue. As the length of the alkyl chain increased, tissue uptake and retention also increased due to hydrophobic interaction with lipiodol. Among the synthesized compounds, the lipiodol solution of 188Re-HDD, the DD derivative with the longest side chain (C16), is a promising agent for therapy of liver cancer.

Effect of formaldehyde on the expression of adhesion molecules in nasal microvascular endothelial cells: the role of formaldehyde in the pathogenesis of sick building syndrome

BACKGROUND

Formaldehyde is associated with sick building syndrome (SBS), a set of diffuse and irritative symptoms predominantly involving the eyes and the respiratory tract. However, its pathophysiological mechanism in SBS has not yet been clarified.

OBJECTIVE

In this study we investigated the effect of formaldehyde on the expression of adhesion molecules on human mucosal microvascular endothelial cells (HMMECs). Furthermore, we investigated the effect of formaldehyde on adhesiveness of HMMECs to eosinophils.

MATERIALS AND METHODS

HMMECs were incubated with various concentrations of formaldehyde (1 ng/mL-1 microg/mL) for 24 h, and the expressions of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM-1) on HMMECs were evaluated by flow cytometry. The change in the expression of ICAM-1 and VCAM-1 mRNA was then evaluated by reverse transcriptase polymerase chain reaction. To understand the role of formaldehyde in eosinophilic inflammation of the nasal mucosa, we examined the effects of formaldehyde on the adhesiveness between HMMECs and eosinophils by eosinophil adhesion assay.

RESULTS

Formaldehyde increased the surface expressions of ICAM-1 and VCAM-1 on HMMECs. Formaldehyde also induced ICAM-1 and VCAM-1 mRNA. In addition, the adhesiveness between HMMECs and eosinophils was also increased by formaldehyde.

CONCLUSION

These in vitro studies suggest that formaldehyde may play a role as the irritant of the nasal mucosa by increasing the expressions of adhesion molecules on HMMECs and by enhancing the adhesiveness between HMMECs and eosinophils.

Polynitroxylated starch/TPL attenuates cachexia and increased epithelial permeability associated with TNBS colitis

Free radicals play an important role in the initiation and progression of inflammatory bowel disease (IBD). Therefore, the reduction or elimination of adverse oxidant effects can provide novel therapy for IBD. Here, the antioxidant capacity and protective effects of a new class of chemically modified hetastarch (polynitroxyl starch, or PNS) plus 4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl (Tempol or TPL) (PNS/TPL) were assessed in a model of colitis. The superoxide scavenging capacity of PNS/TPL-that is, the inhibition of the reduction of cytochrome c in the presence of xanthine/xanthine oxidase (X/XO)-was evaluated in vitro. The effects of PNS/TPL on X/XO-induced neutrophil endothelial adhesion in vitro were investigated. Also, this study tested the protection produced by PNS/TPL in a mouse model of trinitrobenzene sulfonic acid (TNBS)-induced colitis. PNS/TPL was given intravenously immediately before (< 30 min) and intraperitoneally at 24 and 72 hr after TNBS induction. The body weight and survival rate of the mice were checked daily. Colonic mucosal damage was assessed on the 7th day by measuring intestinal permeability to Evans blue (EB) in vivo. The ability of PNS to reoxidize bioreduced TPL was documented by whole-body electron paramagnetic resonance (EPR) detection. We found that PNS or TPL exhibits superoxide dismutase (SOD)-like activity, with approximately 2% of SOD activity occurring on a molar basis. The endothelial-neutrophil adherence induced by X/XO was significantly inhibited by PNS/TPL but not by TPL alone. PNS/TPL protected against cachexia and mortality, both usually induced by TNBS. Epithelial permeability was increased significantly in TNBS mice but was ameliorated by the administration of PNS/TPL. In conclusion, PNS/TPL may be beneficial in the treatment or prevention of IBD through its antioxidant effects, which inhibit oxidant-mediated leukocyte adhesion and injury to endothelial cells.

PDMS-based polyurethanes with MPEG grafts: mechanical properties, bacterial repellency, and release behavior of rifampicin

PDMS-based polyurethanes (PUs) grafted with monomethoxy poly(ethylene glycol) (MPEG) were synthesized to develop a coating material for urinary catheters with a silicone surface for minimizing urinary tract infections. MPEG was grafted on PDMS-based PUs by two methods depending on the PU synthetic routes: esterification and allophanate reactions. It was confirmed from mechanical characterization that an increase of the hard segment amount enhanced the ultimate strength and Young's modulus, while reducing elongation at the end-points. The incorporation of MPEG in PDMS-based PUs induced a decrease in tensile strength and Young's modulus, and increased elongation at the break point due to its high flexibility. When hydrated in distilled water, mechanical properties of all PUs synthesized in this study deteriorated due to water absorption. It was evident from the bacterial adhesion test that PDMS-based PUs showed moderate resistance to adhesion of E. coli on their surfaces compared to Pellethane, while the incorporation of MPEG significantly enhanced repellency to bacteria, including E. coli and S. epidermidis. We also studied the release behavior of an antibiotic drug, rifampicin, from the polymeric devices fabricated by solvent evaporation. Although rifampicin is hydrophilic and soluble in pH 7.4 phosphate buffer, it showed a sustained release over 45 days from PDMS-based PUs with MPEG that were grafted on ethylene glycol residues by allophanate reaction. This release characteristic was predominantly influenced by a hydrogen bond interaction between the polymers and rifampicin, which was confirmed through an ATR-IR study. This may imply that the specific interaction is responsible for the delayed release. Considering the mechanical properties, morphologies of drug-incorporated polymeric matrices, and drug release behaviors, PDMS-based PU with MPEG that were grafted on ethylene glycol (a chain extender) residues by allophanate reaction showed better material properties for uretharal catheter coating pusposes in order to minimize urinary tract infections.

Amperometric TNT biosensor based on the oriented immobilization of a nitroreductase maltose binding protein fusion

The preparation and characterization of an amperometric 2,4,6-trinitrotoluene (TNT) biosensor based on the surface immobilization of a maltose binding protein (MBP) nitroreductase (NR) fusion (MBP-NR) onto an electrode modified with an electropolymerized film of N-(3-pyrrol-1-ylpropyl)-4,4'-bipyridine (PPB) are described. The MBP domain of MBP-NR exhibits a high and specific affinity toward electropolymerized films of PPB with the immobilized enzyme retaining virtually all of its enzymatic activity. Under similar conditions, the wild-type NR enzyme (i.e., without the MBP domain) loses most of its enzymatic activity. The kinetics of the catalytic reaction between the biosensor and TNT and 2,4-dinitrotoluene (DNT) were characterized using rotated disk electrode and cyclic voltammetry techniques, and values of 1.4 x 10(4) and 7.1 x 10(4) M(-1) s(-1) were obtained for TNT and DNT, respectively. The apparent Michaelis-Menten constants (KM) for MBP-NR in solution and on the surface, using TNT as substrate, were determined to be 27 and 95 microM, respectively. The corresponding value for "wild-type" NR in solution containing TNT was 78 microM, which is very close to the value obtained for MBP-NR on the surface. The limits of detection for both TNT and DNT were estimated to be 2 microM, and the sensitivities were determined to be 205 and 222 nA/microM, respectively.

Development of MCTS technique for 3-PM liquid scintillation counting

We have developed a multi-channel time scaling method that is suitable for activity measurement of beta emitting nuclides by means of 3-PM Liquid Scintillation Counting, using non-extending dead times and linear amplifiers. Since it enables to obtain the accidental coincidences directly, the true values for both double and triple coincidences are determined by simply taking into account the correction due to dead times. The advantages of the method are demonstrated by studying the activity of 204Tl and 14C. The measured results were compared with those derived by using the mathematical formulae.

Denitrification of high NO3(-)-N containing wastewater using elemental sulfur; nitrogen loading rate and N2O production

The effects of both concentration and loading rates of nitrate on denitrification efficiency and N2O production during the autotrophic denitrification with elemental sulfur were evaluated. Experiments were conducted with three continuously fed sulfur packed bed reactors (SPBRs) with different influent nitrate concentrations. The loading rate at which nitrate removal efficiency was greater than 95% decreased from 2.46 to 1.64 kg NO3(-)-N m(-3) day(-1) as the influent NO3(-)-N concentration increased from 175 to 700 mg 1(-1). The nitrate removal rate per unit volume of sulfur layer can be expressed as alpha (ALR)n, where ALR is the applied loading rate. The range of alpha and n values were 0.72-0.83 and 0.91-0.94, respectively. The maximum nitrate removal rate was estimated as 3.9 to 4.5 kg NO3(-)-N m(-3) day(-1) depending on the influent NO3(-)-N concentration. The loading rate for complete denitrification without N2O production was 1.37 kg NO3(-)-N m(-3) day(-1) at the influent NO3(-)-N concentration of 175 mg 1(-1). N2O production became significant when the influent nitrate concentration increased while the loading rate remained the same. The batch test indicated that the amount of N2O production per unit mass of nitrogen was greater with nitrite than with nitrate showing that N2O production was directly related to the concentration of nitrite and nitrate.

A divalent recombinant immunotoxin formed by a disulfide bond between the extension peptide chains

Recombinant immunotoxin for the treatment of cancer was made by connecting toxins to 'carcinoma-specific' antibodies that selectively bind to cancer cells, then kills them without harming the normal cells. The divalent recombinant immunotoxin, [B3(Fab)-ext-PE38]2, is a derivative of B3(Fab)-PE38. B3(Fab)-PE38 was made by fusing the Fab domain of the monoclonal antibody (MAb) B3 to PE38, a truncated mutant form of Pseudomonas exotoxin (PE). In this study, B3(Fab)-ext-PE38 was constructed, which has the hinge region of the B3(Fab)-PE38 extended with the peptide extension, G4C(G4S)2, and connected to the C3 connector. The Cys residue of the extension peptide chain makes the disulfide bond between the two Fab domains. The extension sequence (ext) makes the dimerization of B3(Fab)-ext-PE38 easier to form the divalent immunotoxin, because it decreases the steric hindrance between the two PE38s. The constructed genes were expressed in E. coli as inclusion bodies. Polypeptides that were obtained from the inclusion body were refolded, and the active forms were purified. The ID50 values of the divalent molecule, [B3(Fab)-ext-PE38]2, were about 4 ng/ml on A431 cell lines, about 1 ng/ml on CRL1739 cell lines, and 5 ng/ml on MCF-7 cell lines. The [B3(Fab)-ext-PE38]2 showed about a 12-fold higher cytotoxicity on CRL1739 cell lines than B3(scFv)-PE40 did.

Specific detection of cell surface-displayed human melanocortin 4 receptors with antibodies generated in mice

The melanocortin-4 receptor (MC-4R) is a 7-transmembrane protein, which is involved in the central regulation of appetite and obesity. Despite the great interest in this protein, tools for detecting this molecule (as expressed on the cell surface in its native state) have been unavailable. Radioactive- or otherwise labeled ligands showed low receptor specificity to this particular melanocortin receptor isotype. Also, the antibodies were only available for epitopes that were displayed in the cytoplasm. To produce antibodies that enable the detection of this receptor (as expressed on the cell surface without disruption of the target cells), a candidate epitope was selected from the extracellular domains by a computer-aided analysis of the IC-4R secondary structure. This particular region was then recombinantly expressed in E. coli. Immunization of BALB/c mice with the recombinant proteins induced a specific immune reaction, which resulted in the production of MC-4R-specific antibodies. Enzyme-linked immunosorbent assays confirmed the specificity of these antibodies. To examine whether this tool also reacts with native cell surface-displayed MC-4R, HEK-293 cells were transfected with the human MC-4R cDNA. They were analyzed with these antibodies using Western blot and flow cytometry. Specificity and exclusion of cross-reactivity of these antibodies to other MC receptors were further confirmed by an immunofluorescence analysis of the HEK-293 cells that were transfected with other MC receptor isotypes. It is evident that with the availability of this tool, studies on the cell- and tissue-specificity, as well as the regulation mechanism of the MC-4 receptor, will be largely facilitated.

TCDD-up-regulation of IGFBP-6 and IL-5R alpha subunit genes in vivo and in vitro

Although the potent environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been well known for its immunosuppressive activity, the mechanisms of its action have been difficult to elucidate. This is partly due to its inability to exert its effects in vitro. To further elucidate the underlying mechanisms of TCDD effects, we screened for genes that are regulated by the in vivo TCDD treatment of mice that are challenged with allogeneic tumor cells. RNA, collected from lymphoid organs including the thymus, draining lymph nodes, and bone marrow, was reverse-transcribed to cDNA and hybridized to DNA arrays that consisted of 588 genes (ClonTech, USA). The expression of the NF-kappaB p65, c-jun, and p27(Kip1) genes was increased by the TCDD treatment, as previously reported. In addition, we found that the expression of several genes, which were not reported as regulated by TCDD, were modulated by TCDD. Some genes, including insulin-like growth factor-binding protein-6 (IGFBP-6) and IL-5R alpha, were upregulated; while other genes, including CD14, were down-regulated. The expression of the IGFBP-6 and IL-5R alpha subunit genes by TCDD in the thymus was confirmed by RT-PCR and Western blot analyses. Furthermore, TCDD effects on the expression of the IGFBP-6 gene was also observed with EL4 mouse thymoma cells. This suggests that IGFBP-6 may be involved in thymic atrophy, and EL4 cells may be used as an in vitro model for studying molecular mechanisms of thymic atrophy.

Pharmacological preconditioning with low-dose cyclosporine or FK506 reduces subsequent ischemia/reperfusion injury in rat kidney

BACKGROUND

Ischemia/reperfusion (I/R) injury in the early posttransplant period is closely associated with delayed recovery of graft function, increased acute rejection, and late allograft dysfunction. Pharmacological preconditioning with low-dose cyclosporine (CsA) or FK506 was performed to induce ischemic tolerance in rat kidney with I/R injury.

METHODS

Low-dose CsA (3 mg/kg, administered i.v.) or FK506 (0.3 mg/kg i.v.) were used to induce ischemic tolerance in Sprague-Dawley rats, and the induction of heat shock protein (hsp) 70 by CsA or FK506 was evaluated overtime. Rats were pretreated with CsA or FK506 6 hr before I/R injury when hsp70 was maximally expressed, and were killed 24 hr later. The effect of pharmacological preconditioning on subsequent I/R injury was evaluated in terms of renal function, histopathology score, assays for apoptosis (DNA fragmentation analysis, TUNEL staining, expressions of pro-apoptotic genes, and caspase activity), and the expression of inflammatory cytokine genes (interleukin-1 and tumor necrosis factor-alpha).

RESULTS

Preconditioning with low-dose CsA or FK506 significantly improved renal function and renal histology, compared to rats with I/R injury. Apoptotic cell death (typical DNA laddering and increased TUNEL-positive cells) in rat kidneys with I/R injury, was decreased by pretreatment with low-dose CsA or FK506. Increased expression of pro-apoptotic genes (Fas, Fas-ligand, caspase 1 and 3) and activated caspases in ischemic rat kidneys were decreased after CsA or FK506 pretreatment.

CONCLUSIONS

Pretreatment with low-dose CsA or FK506 prevents subsequent I/R injury, and this effect may be related to the induction of hsp70. Pretreatment of renal donors with low-dose CsA or FK506 may result in an improvement in immediate posttransplant function.

Juniper oil inhibits the heat shock-induced apoptosis via preventing the caspase-3 activation in human astrocytes CCF-STTG1 cells

BACKGROUND

Brain astrocytes play a pivotal role in neuronal activities.

METHODS

An investigation was undertaken to determine whether juniper oil inhibits heat shock-induced apoptosis of astrocytes.

RESULTS

Juniper oil inhibited the heat shock-induced apoptosis in human astrocyte CCF-STTG1 cells. Pretreatment of the cells with juniper oil inhibited the heat shock-induced DNA fragmentation and condensation of nuclear chromatin. Juniper oil alone did not affect the apoptosis. Juniper oil inhibited the heat shock-induced caspase-3 activation and poly-ADP-ribose polymerase (PARP) fragmentation in the human astrocytes.

CONCLUSIONS

Juniper oil may inhibit the apoptosis of astrocytes by preventing the caspase-3 activation.

Recurrent pseudotumor cerebri in systemic lupus erythematosus: a case report

Pseudotumor cerebri is an uncommon manifestation of neuropsychiatric systemic lupus erythematosus (SLE), and is characterized by an elevated intracranial pressure, papilledema with occasional abducens nerve paresis, absence of a space-occupying lesion or ventricular enlargement, and normal cerebrospinal fluid chemical and hematological constituents. Pseudotumor cerebri has been reported in a few sporadic cases in patients with systemic lupus erythematosus. However, the recurrent pseudotumor cerebri in patients with systemic lupus erythematosus which has been rarely reported, has not been reported in Korea. We experienced a 30-yr-old female patient with SLE who was presented with second attack of severe intractable headache. She was diagnosed pseudotumor cerebri twice and successfully treated with corticosteroid. Headache is the common symptom in patients with neuropsychiatric SLE and attributable to various causes. We suggest that it is important to define the cause of headache in patients with SLE and pseudotumor cerebri should be included in the spectrum of clinical manifestations during the course of SLE as a cause of headache.

The antioxidant potential of pyruvate in the amitochondriate diplomonads Giardia intestinalis and Hexamita inflata

Giardia intestinalis and Hexamita inflata are microaerophilic protozoa which rely on fermentative metabolism for energy generation. These organisms have developed a number of antioxidant defence strategies to cope with elevated O(2) tensions which are inimical to survival. In this study, the ability of pyruvate, a central component of their energy metabolism, to act as a physiological antioxidant was investigated. The intracellular pools of 2-oxo acids in G. intestinalis were determined by HPLC. With the aid of a dichlorodihydrofluorescein diacetate-based assay, intracellular reactive oxygen species generation by G. intestinalis and H. inflata suspensions was monitored on-line. Addition of physiologically relevant concentrations of pyruvate to G. intestinalis and H. inflata cell suspensions was shown to attenuate the rate of H(2)O(2)- and menadione-induced generation of reactive oxygen species. In addition, pyruvate was also shown to decrease the generation of low-level chemiluminescence arising from the oxygenation of anaerobic suspensions of H. inflata. In contrast, addition of pyruvate to suspensions of respiring Saccharomyces cerevisiae was shown to increase the generation of reactive oxygen species. These data suggest that (i) in G. intestinalis and H. inflata, pyruvate exerts antioxidant activity at physiological levels, and (ii) it is the absence of a respiratory chain in the diplomonads which facilitates the observed antioxidant activity.

Attention and motor performance: preferences for and advantages of an external focus

This study examined individuad differences in the preference for and effectiveness of the type of attentional focus for motor learning. In two experiments, participants practicing a balance task (stabilometer) were asked to find out whether focusing on their feet (internal focus) or on two markets in front of their feet (external focus) was more effective. In Experiment 1, participants switched their attentional focus from trial to trial on Day 1 and used their preferred attentional focus on Day 2. In Experiment 2, participants were free to switch their attentional focus any time during 2 days of practice. Retention tests were performed on Day 3. Most participants chose an external focus. Also, they were more effective in retention than participants who preferred an internal focus.

Single-source precursors to ternary silver indium sulfide materials

Compounds of type [(Ph3P)2AgIn(SC(O)R)4] (R = Me (1), Ph (2)) are excellent single-source precursors for AgInS2 bulk materials by pyrolysis and AgIn5S8 films by aerosol assisted chemical vapour deposition (AACVD).

Hepatitis B virus X protein induced expression of the Nur77 gene

Hepatitis B virus (HBV) X protein (HBx) plays an essential role in development of HBV-associated hepatocellular carcinoma (HCC). Recently, we reported that HBx induces Fas Ligand (FasL) expression, which may help HCC cells to evade host-immune surveillance. The aim of this study was to investigate the role of HBx in expression of Nur77, an orphan nuclear receptor implicated in the upregulation of FasL. When Chang X-34 expressing HBx under the control of a doxycycline-inducible promoter was examined, induction of Nur77 was observed following HBx expression. Blocking of Nur77 function by introduction of an antisense or a dominant negative mutant Nur77 significantly inhibited the induction of FasL, indicating that Nur77 plays critical roles in FasL expression. Further, a high-level expression of transcripts and DNA binding of Nur77 were observed in the HBV-integrated cell lines established from HCC patients that express HBx. These results suggested that Nur77 may contribute to leading the HBx-induced Fas/FasL signaling pathway which eliminates invading Fas-expressing lymphocytes.

Activation of PKC but not of ERK is required for vitamin E-succinate-induced apoptosis of HL-60 cells

Vitamin E-succinate (VES) induced HL-60 human leukemia cells to undergo apoptosis. Treatment with VES induced membrane translocation of Fas; cleavages of caspase-3, PARP, and lamin B; hypophosphorylation of retinoblastoma protein; and increase of p21(WAF1) protein level. During the induction of apoptosis, activity of PKC was gradually increased with downregulation of VES-induced ERK activity and accompanied by activation of caspase-3. Inhibition of PKC by GF109203X blocked VES-mediated membrane translocation of PKC-alpha and cleavage of caspase-3 cascade, resulting in prevention of VES-induced apoptosis. On the contrary, PKC activation by cotreatment with LPC or thapsigargin and VES synergistically increased VES-mediated apoptosis. However, inhibition of ERK activity by PD98059 showed no significant effect on VES-induced PKC activity and apoptosis. Taken together, our data suggest that VES induces activation of PKC and PKC-dependent hypophosphorylation of retinoblastoma protein, which results in induction of apoptosis, and that VES-induced early activation of ERK and ERK-dependent induction of p21(WAF1) are not required for apoptosis.

Inhibitory activity of Bifidobacterium longum HY8001 against Vero cytotoxin of Escherichia coli O157:H7

Vero cytotoxin (VT)-producing Escherichia coli (VTEC), such as E. coli O157:H7, are emerging foodborne pathogens worldwide. VTs are associated with hemorrhagic colitis and hemolytic uremic syndrome in humans. Attachment of the B subunit of VTs to its receptor, globotriaosylceramide (Gb3), at gut epithelium is the primary step and, consequently, the A subunit of VTs inhibits protein synthesis in the target cell. Proinflammatory cytokines, such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta, up-regulate Gb3 expression, increase sensitivity to VTs, and enhance VT action in developing disease. Currently, there is a growing interest in probiotics, given the increasing occurrence of antibiotic-resistant bacteria. In particular, much work on bifidobacteria among probiotics, regarded as microorganisms targeted for technological and therapeutic applications, has been performed. In Korea, the neutralizing effect of the culture supernatant of Bifidobacterium longum HY8001, Korean isolate, against the VTs from E. coli O157:H7 was found. Therefore, this study focused on the raveling of the inhibitory effect of B. longum HY8001 against VTs, through the interference B subunit of VTs and Gb3 interaction. Mice were inoculated intragastrically with B. longum HY8001 culture supernatant before and after challenge with E. coli O157:H7. Control mice were inoculated intragastrically only with E. coli O157:H7. Cytokine, TNF-alpha, and IL-1beta levels in sera and expression of their mRNA were decreased, and expression of Gb3 in renal tubular epithelial cells was reduced in mice treated with B. longum HY8001 culture supernatant. In competitive enzyme-linked immunosorbent assays (ELISAs), the culture supernatant of B. longum HY8001 primarily binds VTs to interfere the VTs with Gb3 interaction. These results suggest that soluble substance(s) in B. longum HY8001 culture supernatant may have inhibitory activity on the expression of Gb3, VT-Gb3 interaction, or both. Further study should be done to elucidate the property of soluble substances in B. longum HY8001 culture supernatant.

Assessment of stress response of the probiotic Lactobacillus acidophilus

Different aspects of stress response of Lactobacillus acidophilus were investigated. First, the sublethal and lethal levels of bile, heat, and NaCl stresses were determined. They were 0.05% and 0.5% (bile), 53 degrees C and 60 degrees C (heat), and 2% and 18% (NaCl), respectively. To evaluate the effect of each stress at log phase, log-phase cultures were challenged directly with the lethal level of each stress (control) and were compared to log-phase cultures that were pre-exposed to the sublethal level prior to the exposure at the lethal level (test). Some, if not most, of the cells were killed in the control cultures against each of the three stresses. However, in the test cultures, the number of cells that had survived increased significantly. It appears that L. acidophilus is capable of displaying adaptive response to stress. The adaptive response to one stress was also shown to provide cross-protection against different stresses tested. The effect of each stress on stationary-phase cultures was also investigated. In contrast to log-phase culture, stationary-phase culture was inherently resistant to stress.

Dietary conjugated linoleic acid (CLA) induces apoptosis of colonic mucosa in 1,2-dimethylhydrazine-treated rats: a possible mechanism of the anticarcinogenic effect by CLA

One of the objectives of the present study was to investigate whether 1 % conjugated linoleic acid (CLA) in the diet reduced tumour incidence in the colon of 1,2-dimethylhydrazine (DMH)-treated rats. Colon cancer was induced by injecting 6-week-old, male, Sprague-Dawley rats with 15 mg/kg DMH twice per week for 6 weeks. They were fed either 1 % CLA or a control diet ad libitum for 30 weeks. Dietary CLA significantly decreased colon tumour incidence (P<0.05). Our second objective was to investigate whether apoptosis in the colon mucosa of DMH-treated rats was affected by the amount of dietary CLA and whether the changes in apoptosis were related to those in fatty acid-responsive biomarkers. For this purpose, rats were killed after being fed a diet containing 0 %, 0.5 %, 1 % or 1.5 % CLA for 14 weeks. CLA was undetected in the mucosa of rats fed the 0 % CLA diet and increased to 5.9 mg/g phospholipid in rats fed the 0.5 % diet. The apoptotic index estimated by the terminal deoxynucleotidyl transferase-mediated dUTP nick and labelling technique was increased by 251 % and the 1,2-diacylglycerol content was decreased by 57 % in rats fed 0.5 % CLA. No further changes in these variables were observed when CLA in the diet was raised to 1.0 % or 1.5 %. However, dietary CLA decreased mucosal levels of prostaglandin E2, thromboxane B2 and arachidonic acid in a dose-dependent manner. The present data indicate that dietary CLA can inhibit DMH-induced colon carcinogenesis by mechanisms probably involving increased apoptosis.