Controlled Secretion of the Anticancer Protein MDA-7 from Engineered Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have been explored as a "live" carrier of cytokines for targeted cancer therapy, but, in earlier reports in the literature, the secretion process of therapeutic cytokines was not regulated. The purpose of this study was to generate MSCs to conditionally secrete the melanoma differentiation-associated gene-7 (MDA-7) tumor-suppressor protein. To control the secretion of MDA-7 from MSCs, a well-established tetracycline-controlled transcriptional activation system was incorporated into MDA-7 plasmid. MDA-7 gene expression was induced in the engineered MSCs only in the presence of doxycycline, as characterized by quantitative reverse transcription (qRT)-PCR. Enzyme-linked immunosorbent assay (ELISA) also revealed that the MDA-7 protein was secreted from the engineered MSCs only after the cells had been exposed to doxycycline. Both recombinant human MDA-7 protein and the conditioned medium from the engineered MSCs in the presence of doxycycline significantly inhibited tube formation of human umbilical vascular endothelial cells (HUVECs), indicating that our system could be used for targeted, antiangiogenic therapy. Overall, this study provides useful information on the potential use of engineered MSCs for the controlled secretion of therapeutic proteins, in this case MDA-7, for targeted cancer therapy.

Intrinsic Resistance to 5-Fluorouracil in a Brain Metastatic Variant of Human Breast Cancer Cell Line, MDA-MB-231BR

Although drug resistance is often observed in metastatic recurrence of breast cancer, little is known about the intrinsic drug resistance in such metastases. In the present study, we found, for the first time, that MDA-MB-231BR, a brain metastatic variant of a human breast cancer cell line, was refractory to treatment with 5-fluorouracil (5-FU) even without chronic drug exposure, compared to its parent cell line, MDA-MB-231, and a bone metastatic variant, MDA-MB-231SCP2. Both the mRNA and protein levels of COX-2 and BCL2A1 in MDA-MB-231BR were significantly higher than those in MDA-MB-231 or MDA-MB-231SCP2. Neither the COX-2 inhibitor celecoxib nor the NF-κB inhibitor BAY11-7082 could sensitize MDA-MB-231BR to 5-FU, indicating that COX-2 plays little, if any, role in the resistance of MDA-MB-231BR to 5-FU. Although BCL2-family inhibitor ABT-263 failed to sensitize MDA-MB-231BR to 5-FU at a dose at which ABT-263 is considered to bind to BCL2, BCL2-xL, and BCL2-w, but not to BCL2A1, ABT-263 did sensitize MDA-MB-231BR to 5-FU to a level comparable to that in MDA-MB-231 at a dose of 5 μM, at which ABT-263 may disrupt intracellular BCL2A1 protein interactions. More importantly, BCL2A1 siRNA sensitized MDA-MB-231BR to 5-FU, whereas the overexpression of BCL2A1 conferred 5-FU-resistance on MDA-MB-231. These results indicate that BCL2A1 is a key contributor to the intrinsic 5-FU-resistance in MDA-MB-231BR. It is interesting to note that the drug sensitivity of MDA-MB-231BR was distinct from that of MDA-MB-231SCP2 even though they have the same origin (MDA-MB-231). Further investigations pertinent to the present findings may provide valuable insight into the breast cancer brain metastasis.

Growth, respiration and nutrient acquisition by the arbuscular mycorrhizal fungus Glomus mosseae and its host plant Plantago lanceolata in cooled soil

Although plant phosphate uptake is reduced by low soil temperature, arbuscular mycorrhizal (AM) fungi are responsible for P uptake in many plants. We investigated growth and carbon allocation of the AM fungus Glomus mosseae and a host plant (Plantago lanceolata) under reduced soil temperature. Plants were grown in compartmented microcosm units to determine the impact on both fungus and roots of a constant 2.7 °C reduction in soil temperature for 16 d. C allocation was measured using two (13)CO(2) pulse labels. Although root growth was reduced by cooling, AM colonization, growth and respiration of the extraradical mycelium (ERM) and allocation of assimilated (13)C to the ERM were all unaffected; the frequency of arbuscules increased. In contrast, root respiration and (13)C content and plant P and Zn content were all reduced by cooling. Cooling had less effect on N and K, and none on Ca and Mg content. The AM fungus G. mosseae was more able to sustain activity in cooled soil than were the roots of P. lanceolata, and so enhanced plant P content under a realistic degree of soil cooling that reduced plant growth. AM fungi may therefore be an effective means to promote plant nutrition under low soil temperatures.

Relationship between developmental synaptic modulation and conditioning-induced synaptic change in Lymnaea

Though adult Lymnaea are bimodal breathers, young animals breathe mainly through the skin and adults through the lung. Operant conditioning changes adult breathing behavior from aerial to cutaneous. We hypothesized that this behavioral change is caused by alterations in the neuronal circuit during both development and conditioning. We focused our study on whether the synaptic connection between RPeD1 and RPA6 neurons is modulated during development and conditioning. Our findings indicated that the RPeD1 has an excitatory monosynaptic contact with the RPA6 in young naive and operantly-conditioned adult animals. The relationship of this contact was well correlated with their respiratory behavior.

Antimicrobial susceptibility of 800 anaerobic isolates from patients with dentoalveolar infection to 13 oral antibiotics

INTRODUCTION

The aim of this study was to determine the current antimicrobial susceptibility of the principle anaerobic pathogens involved in dentoalveolar infection, to 13 oral antibiotics, and to assess the value of each antibiotic in the management of the infection.

METHODS

A total of 800 isolates from patients with dentoalveolar infection (Prevotella species, Fusobacterium species, Porphyromonas species and Peptostreptococcus micros) were tested for their susceptibility to amoxicillin, amoxicillin/clavulanate, cefaclor, cefuroxime, cefcapene, cefdinir, erythromycin, azithromycin, telithromycin, minocycline, levofloxacin, clindamycin, and metronidazole using an agar dilution method.

RESULTS

Although the majority of Fusobacterium strains were resistant to erythromycin, azithromycin, and telithromycin, the remaining antibiotics demonstrated a high level of antimicrobial activity. P. micros and Porphyromonas species exhibited high susceptibility to all antibiotics tested in this study. In the case of Prevotella species, resistance to amoxicillin occurred in 34% of isolates and all of these resistant strains were found to produce beta-lactamase. Susceptibility of Prevotella strains to cefaclor, cefuroxime, cefcapene, cefdinir, erythromycin, azithromycin, and minocycline was found to correlate with amoxicillin susceptibility. Amoxicillin/clavulanate, telithromycin, clindamycin, and metronidazole exhibited high antimicrobial activity even against amoxicillin-resistant strains of Prevotella species.

CONCLUSION

Amoxicillin would still be advocated therefore as being a suitable first-line agent, while reduced susceptibility of Prevotella strains remains a matter of concern with penicillins. Amoxicillin/clavulanate, clindamycin, and metronidazole are useful alternatives in combating the anaerobic bacteria involved in dentoalveolar infection.

Ephrin-B1 localizes at the slit diaphragm of the glomerular podocyte

Ephs and ephrins are a family of membrane-bound proteins that function as receptor-ligand pairs. Members of the Eph-ephrin-B family have recently been reported to regulate the paracellular permeability of epithelial cells. In this study, we analyzed the expression and the function of ephrin-B1 in glomeruli. Using immunofluorescence (IF), we found that ephrin-B1 was expressed along the glomerular capillary loop. Immunoelectron microscopy revealed that ephrin-B1 expression was restricted at the slit diaphragm. Dual labeled IF showed ephrin-B1 colocalized with the slit diaphragm proteins nephrin and CD2-associated protein. Ephrin-B1 colocalized with nephrin at the late capillary loop stage of kidney development. Additionally, injection of rats with a nephritogenic anti-nephrin antibody (ANA) reduced ephrin-B1 expression. When podocytes were cultured in vitro, they extruded processes that co-stained for ephrin-B1 and for CD2-associated protein. When these podocytes were treated in culture with small interfering RNA for ephrin-B1, CD2-associated protein was reduced in the processes, with a remaining faint perinuclear staining. We suggest that ephrin-B1 has a role in maintaining barrier function at the slit diaphragm.

The microbial synergy of Peptostreptococcus micros and Prevotella intermedia in a murine abscess model

This study characterized the microbial interaction of Peptostreptococcus micros and Prevotella intermedia, the major pathogens of dentoalveolar infection, using a murine model. Subcutaneous injection of P. micros cells in the dorsum of the mouse together with living cells of P. intermedia resulted in a significantly larger abscess when compared with single injection of the organisms (P < 0.02). The abscess size was also significantly increased (P < 0.05) when the plate-cultured cell suspension of P. micros was injected into mouse with the culture filtrate of P. intermedia. The heat-treated culture filtrate of P. intermedia also enhanced the virulence of P. micros. P. micros culture filtrate did not affect the virulence of P. intermedia. Interestingly, the virulence of P. micros appeared to be enhanced even when the culture filtrate of P. intermedia was injected at separate sites in the mouse. These results suggest that a heat-stable product or products of P. intermedia increase the virulence of P. micros indirectly by altering the host condition, whereas living cells of P. micros can directly enhance virulence of P. intermedia.

Antimicrobial susceptibility of major pathogens of orofacial odontogenic infections to 11 beta-lactam antibiotics

In this study, we evaluated the current effectiveness of 11 beta-lactam antibiotics for treatment of orofacial odontogenic infections by determining the antimicrobial susceptibility of the major pathogens. The antimicrobial susceptibilities of viridans streptococci (n = 47), Peptostreptococcus (n = 67), Porphyromonas (n = 18), Fusobacterium (n = 57), black-pigmented Prevotella (n = 59) and non-pigmented Prevotella (n = 47) isolated from pus specimens of 93 orofacial odontogenic infections to penicillin G, cefmetazole, flomoxef, cefoperazone, cefoperazone/sulbactam, ceftazidime, cefpirome, cefepime, cefoselis, imipenem and faropenem were determined using the agar dilution method. Penicillin G, most cephalosporins, imipenem and faropenem worked well against viridans streptococci, Peptostreptococcus, Porphyromonas and Fusobacterium. Penicillin G and most cephalosporins, including fourth-generation agents, were not effective against beta-lactamase-positive Prevotella, though they were effective against beta-lactamase-negative strains. Cefmetazole, cefoperazone/sulbactam, imipenem and faropenem expressed powerful antimicrobial activity against beta-lactamase-positive Prevotella. In conclusion, penicillins have the potential to be first-line agents in the treatment of orofacial odontogenic infections. Most of the other beta-lactam antibiotics, including fourth-generation cephalosporins, were not found to have greater effectiveness than penicillins. In contrast, cefmetazole, cefoperazone/sulbactam, imipenem and faropenem were found to have greater effectiveness than penicillins.

Bacteriology and antimicrobial susceptibility of gram-positive cocci isolated from pus specimens of orofacial odontogenic infections

We recently reported the beta-lactamase production and antimicrobial susceptibility of anaerobic gram-negative rods isolated from pus specimens of 93 orofacial odontogenic infections. In this report, we determine the bacteriology and antimicrobial susceptibility of bacteria other than anaerobic gram-negative rods, mainly gram-positive cocci, isolated from the same specimens. Streptococcus constellatus and Peptostreptococcus micros were frequent isolates from all types of infection examined. Peptostreptococcus prevotii, Corynebacterium species, and Eubacterium species were recovered only from dentoalveolar infections, while Gemella morbillorum was found more frequently in periodontitis than in the other infections. beta-Lactamase-positive strains were detected only in staphylococci. Ampicillin, ampicillin/sulbactam, cefazolin, cefotaxime, imipenem, erythromycin, clindamycin and levofloxacin showed high susceptibility rates (> or = 77%) against viridans streptococci, Peptostreptococcus and Gemella. Minocycline showed a high MIC90 value against viridans streptococci (32 microg/ml), and metronidazole was effective against Peptostreptococcus and Gemella. These results provide useful information for the treatment of orofacial odontogenic infections.

Effects of the antiplatelet agent TA-993 and its metabolite MB3 on the hemorheological properties of rat and human erythrocytes

In the present study, we investigated the effects of the antiplatelet agent TA-993 and its metabolite MB3 on the hemorheological properties of rat and human erythrocytes in comparison with ticlopidine and aspirin. TA-993 and MB3 concentration-dependently lowered the viscosity of rat erythrocyte suspensions. TA-993 and MB3 inhibited both the hypotonic hemolysis of human erythrocytes and the mechanical hemolysis of rat erythrocytes induced by turbulent flow. Treatment of rats with TA-993 (10 mg/kg/day po) for 10 days significantly increased blood filterability, but ticlopidine and aspirin did not show this effect. TA-993 and MB3 enhanced the interaction of 1-anilino-8-naphthalene sulfonate (ANS), a hydrophobic probe, with human erythrocyte ghosts and reduced the fluorescence polarization in 1,6-diphenyl 1,3,5-hexatriene (DPH, a fluidity probe)-labeled human erythrocyte ghosts. TA-993 and MB3 induced aggregation of liposome suspensions prepared from acidic phospholipids. These findings suggest that TA-993 and MB3 may affect the erythrocyte membrane by interacting with acidic phospholipids and thus improve the hemorheological properties.

Colonisation and transmission of Clostridium difficile in healthy individuals examined by PCR ribotyping and pulsed-field gel electrophoresis

Healthy adults who had not been exposed to antimicrobial agents for the preceding 4 weeks were examined for intestinal carriage of Clostridium difficile. The 1234 individuals examined were composed of seven groups: three classes of university students, hospital workers at two hospitals, employees of a company and self-defence force personnel at a local station. Overall, 94 (7.6%) individuals were positive for C. difficile by faecal culture but carriage rates among the study groups ranged from 4.2% to 15.3%. Typing by PCR ribotyping and pulsed-field gel electrophoresis demonstrated clusters of carriers colonised by a single type in each of three groups, indicating that cross-transmission of C. difficile can occur in community settings. Follow-up culture was performed on 38 C. difficile-positive individuals and C. difficile was isolated again from 12 (32%) of them 5-7 months after the initial culture; six (50%) of these 12 individuals had a new strain on repeat culture. Two or more family members were C. difficile-positive in five of 22 families examined. C. difficile with an identical type was isolated from persons within a family in only one family. These results suggest that intestinal carriage by healthy adults may play a role as a reservoir for community-acquired C. difficile-associated diarrhoea, but that cross-transmission of C. difficile does not occur frequently among family members at home.

Specific immunoglobulin E responses in ZAP-70-deficient patients are mediated by Syk-dependent T-cell receptor signalling

ZAP-70 deficiency is a rare primary immunodeficiency characterized by the absence of peripheral CD8+ T cells and defects in T-cell receptor (TCR) signalling. T cells in ZAP-70-deficient patients are assumed to have no helper functions for B-cell immunoglobulin synthesis, whereas the patients rarely have antigen-specific antibodies. We experienced a ZAP-70-deficient patient, who had immunoglobulin E (IgE) antibodies specific to food allergens, and we investigated the mechanisms of switching to IgE in the patient. Peripheral blood mononuclear cells from the patient did not proliferate upon stimulation with the antigens but produced distinct levels of interleukin-4 (IL-4). Cell sorting analysis indicated that the cells that produced IL-4 in response to the antigens were enriched in CD4+ T cells. Purified CD4+ T cells from the patient produced IL-4 and expressed CD40L upon stimulation with anti-CD3. Moreover, CD4+ T cells pretreated with anti-CD3 induced mature epsilon transcript on naive B cells. Since the results indicated that there remained sufficient T-cell receptor (TCR)-signalling in the patient's T cells to exert antigen-specific IgE switching on B cells, we next investigated the expression of the ZAP-70-homologous kinase Syk. Syk was present in high levels in patient's CD4+ T cells and was tyrosine-phosphorylated after TCR stimulation. Inhibition of Syk by piceatannol resulted in decreased production of IL-4 and expression of CD40L on patient's CD4+ T cells. Moreover, Syk was expressed on all human T-cell leukaemia virus (HTLV-1)-transformed T-cell lines derived from peripheral blood of the patient, whereas it was low or undetectable in control lines. It was therefore concluded that specific IgE responses in the patient were most likely to be mediated by Syk-dependent TCR-signalling.

Inhibitory effects of TA-993 and its metabolite MB3 on platelet activation induced by collagen and U-46619 in human platelets

In the present study, we investigated the effects of TA-993 and its metabolite MB3 on platelet activation in vitro. TA-993 and MB3 concentration-dependently inhibited platelet aggregation and ATP release induced by collagen in human platelets. Thromboxane (Tx) A2 formation, as determined by the production of TxB2, and the increase in intracellular Ca2+ concentration ([Ca2+]i) were also suppressed by TA-993 and MB3. TA-993 and MB3 did not inhibit TxA2 formation caused by arachidonic acid. These results suggest that the inhibition of platelet activation by TA-993 and MB3 is partly mediated by an inhibition of TxA2 formation at a step prior to cyclooxygenase. Furthermore, TA-993 and MB3 inhibited U-46619-induced platelet aggregation without blockade of the increase in [Ca2+]i, suggesting that they are likely to exert some additional effects on the intracellular events induced by Ca2+.

Incidence of beta-lactamase production and antimicrobial susceptibility of anaerobic gram-negative rods isolated from pus specimens of orofacial odontogenic infections

The incidence of beta-lactamase production in anaerobic gram-negative rods isolated from 93 pus specimens of orofacial odontogenic infections and the antimicrobial susceptibility of these isolates against 11 antibiotics were determined. A total of 191 anaerobic gram-negative rods were isolated from the specimens. Beta-lactamase was detected in 35.6% of the black-pigmented Prevotella and 31.9% of the nonpigmented Prevotella. However, no strains among the other species isolated produced beta-lactamase. Ampicillin, cefazolin and cefotaxime showed decreased activity as regards beta-lactamase-positive Prevotella strains, whereas the activity of ampicillin/sulbactam, cefmetazole, and imipenem continued to be effective against such strains. All tested beta-lactam antibiotics were effective against Porphyromonas and Fusobacterium. Erythromycin showed decreased activity against nonpigmented Prevotella and Fusobacterium. Clindamycin, minocycline and metronidazole were powerful antibiotics against which anaerobic gram-negative rods could be tested. The present study showed that beta-lactamase-positive strains were found more frequently in the Prevotella strains than in any of the other species of anaerobic gram-negative rods. The effectiveness of adding sulbactam to ampicillin was demonstrated, as well as the difference in cephalosporin activity against beta-lactamase-positive strains.

Genetic analysis of type E botulinum toxin-producing Clostridium butyricum strains

Type E botulinum toxin (BoNT/E)-producing Clostridium butyricum strains isolated from botulism cases or soil specimens in Italy and China were analyzed by using nucleotide sequencing of the bont/E gene, random amplified polymorphic DNA (RAPD) assay, pulsed-field gel electrophoresis (PFGE), and Southern blot hybridization for the bont/E gene. Nucleotide sequences of the bont/E genes of 11 Chinese isolates and of the Italian strain BL 6340 were determined. The nucleotide sequences of the bont/E genes of 11 C. butyricum isolates from China were identical. The deduced amino acid sequence of BoNT/E from the Chinese isolates showed 95.0 and 96.9% identity with those of BoNT/E from C. butyricum BL 6340 and Clostridium botulinum type E, respectively. The BoNT/E-producing C. butyricum strains were divided into the following three clusters based on the results of RAPD assay, PFGE profiles of genomic DNA digested with SmaI or XhoI, and Southern blot hybridization: strains associated with infant botulism in Italy, strains associated with food-borne botulism in China, and isolates from soil specimens of the Weishan lake area in China. A DNA probe for the bont/E gene hybridized with the nondigested chromosomal DNA of all toxigenic strains tested, indicating chromosomal localization of the bont/E gene in C. butyricum. The present results suggest that BoNT/E-producing C. butyricum is clonally distributed over a vast area.

Bacteriologic features and antimicrobial susceptibility in isolates from orofacial odontogenic infections

OBJECTIVE

The aim of this study was to obtain information for an effective antimicrobial therapy against orofacial odontogenic infections; such information was obtained from recent bacteriologic features and antimicrobial susceptibility data.

STUDY DESIGN

The bacteriology and antimicrobial susceptibility of major pathogens in 163 patients with orofacial odontogenic infections to 7 antibiotics was examined.

RESULTS

Mixed infection of strict anaerobes with facultative anaerobes (especially viridans streptococci) was observed most often in dentoalveolar infections, periodontitis, and pericoronitis. Penicillin (penicillin G) was effective against almost all pathogens, although it did not work well against beta-lactamase-positive Prevotella. Cefmetazole was effective against all test pathogens. Erythromycin was ineffective against viridans streptococci and most Fusobacterium. Clindamycin exerted a strong antimicrobial activity on anaerobes. Minocycline was effective against almost all the test pathogens. The antimicrobial activity of levofloxacin against viridans streptococci was not strong.

CONCLUSIONS

An antibiotic that carries out antimicrobial activity against both viridans streptococci and oral anaerobes should be suitable for treatment of dentoalveolar infection, periodontitis, and pericoronitis. Penicillin remains effective as an antimicrobial against most major pathogens in orofacial odontogenic infections. Cefmetazole, clindamycin, and minocycline may be effective against most pathogens, including penicillin-unsusceptible bacteria.

The virulence of mixed infection with Streptococcus constellatus and Fusobacterium nucleatum in a murine orofacial infection model

Orofacial infections are usually polymicrobial, and it is the microbial interactions of pathogenic species that cause tissue destruction. In this study, the microbial interaction between Streptococcus constellatus and Fusobacterium nucleatum was characterized using a murine orofacial infection model. A mixture of viable S. constellatus and F. nucleatum cells (both 2 x 10(8) CFU/mouse) was injected into the submandible; as a result, all of the test mice died. In contrast, none of the experimental animals monoinjected with either S. constellatus or F. nucleatum died (P<0.001), indicating that the synergism between the two resulted in the virulence. When a mixture of viable S. constellatus cells and a culture filtrate of F. nucleatum was tested, lethality and the bacterial cell count per lesion were significantly enhanced as compared with monoinjections (P<0.02). However, the virulence of F. nucleatum was not enhanced by infection of a culture filtrate of S. constellatus. The enhancement of virulence was observed even when viable S. constellatus cells and the culture filtrate of F. nucleatum were injected at separate sites. Heat treatment of the culture filtrate of F. nucleatum did not affect the enhancement. These results indicate that a heat-stable substance(s) produced by F. nucleatum contributes to the microbial synergy of S. constellatus and F. nucleatum in orofacial infections.

Spontaneous regression of hepatocellular carcinoma and review of literature

A 68-year-old man presented with multiple hepatocellular carcinoma, which was considered to be unresectable at the first admission in January 1994. Pathological diagnosis was made by biopsy of the one lesion among them. From January 1994 to December 1997, 10 transarterial chemoembolizations and six percutaneous ethanol injection therapies were performed on the tumours in the cirrhotic liver. In February 1998 the tumour situated in the right lobe began to increase in size. The maximum tumour diameter was 6.3 cm measured by computed tomography (CT). In the beginning of May 1998 moderate ascites was present and mild hepatic encephalopathy was noticed. The patient was in the terminal stage of hepatocellular carcinoma and no further treatment was possible at that time. However, serum alpha-fetoprotein and protein induced by vitamin K absence or antagonist II dramatically decreased in June 1998. The CT scan also showed that the tumour had completely regressed without specific treatment. In February 1999 a new biopsy-proven hepatocellular carcinoma, 2 cm in diameter, developed in the lateral segment of the liver. It was well treated by percutaneous ethanol injection therapy. The patient was alive in good condition without any symptoms or tumour recurrence in June 1999. It was concluded that a rare case of spontaneous regression of hepatocellular carcinoma had occurred.

Characterization of bacterial orofacial infections using a new murine model

We devised a new murine orofacial infection model using bacteria from odontogenic infection origins and characterized the experimental infections. In this model, bacteria were injected into the submandible of mice. Streptococcus constellatus and Peptostreptococcus micros produced a single abscess at the injection site and their abscess-forming and lethal abilities were low: the median abscess-forming dose (AF(50)) of S. constellatus and P. micros were 10(8.5-10.7)and 10(10.2-10.6)cfu/mouse, and their median lethal dose (LD(50)) were >11 and 10(10.6-11)cfu/mouse, respectively. Prevotella oralis and Fusobacterium nucleatum produced multiple abscesses and their abscess-forming and lethal abilities were strong: AF(50)of P. oralis and F. nucleatum were 10(6.0-6.4)and 10(7. 0-8.7)cfu/mouse, and their LD(50)were 10(7.0-7.7)and 10(8.3-9. 9)cfu/mouse, respectively. LD(50)of P. intermedia and P. gingivalis were 10(9.4->11)and 10(8.9-9.1)cfu/mouse, respectively. Prevotella intermedia and Porphyromonas gingivalis generated a necrotizing lesion, which progressed rapidly. We conclude that this murine model could reflect human orofacial odontogenic infections and is useful to investigate the pathogenicity of causative bacteria of such infections.

Antiplatelet mechanisms of TA-993 and its metabolite MB3 in ADP-induced platelet aggregation

We investigated the antiplatelet mechanisms of TA-993 [(-)-cis-3-acetoxy-5-(2-(dimethylamino)ethyl)-2, 3-dihydro-8-methyl-2-(4-methylphenyl)-1,5-benzothiazepin-4(5H)-one maleate] and its metabolite MB3 (deacetyl and N-monomethyl TA-993) in human platelets stimulated by ADP in vitro. TA-993 and MB3 concentration-dependently inhibited fibrinogen binding to the ADP-stimulated platelets as well as inhibiting platelet aggregation. The antiplatelet effect of MB3 was about 300 times more potent than those of TA-993 and a glycoprotein IIb/IIIa receptor antagonist, Arg-Gly-Asp-Ser (RGDS). Aggregation of ADP-treated fixed platelets caused by the addition of fibrinogen was inhibited by RGDS but not by TA-993 and MB3. TA-993 and MB3 inhibited ADP-induced polymerization of actin filaments. Neither TA-993 nor MB3 affected cyclic AMP and cyclic GMP levels in resting platelets, and nor suppressed the increase in intracellular Ca(2+) concentration induced by ADP. These results suggest that the antiplatelet mechanisms of TA-993 and MB3 may involve inactivation of glycoprotein IIb/IIIa receptors via inhibition of the polymerization of actin.

Past administration of beta-lactam antibiotics and increase in the emergence of beta-lactamase-producing bacteria in patients with orofacial odontogenic infections

OBJECTIVE

The purpose of this study was to determine the current status of beta-lactamase-producing bacteria in orofacial odontogenic infections.

STUDY DESIGN

Microbiologic data regarding purulent exudate from 111 cases with orofacial odontogenic infections were analyzed in relation to the past administration of beta-lactams.

RESULTS

beta-lactamase-producing bacteria were isolated more frequently from the beta-lactam-administered group (38.5%) than from the beta-lactam-nonadministered group (10.9%; P <.005), and they were isolated more frequently as the duration of administration increased. The predominant bacteria isolated included Prevotella (the most frequent isolate), viridans streptococci, Peptostreptococcus, and Fusobacterium, and 7.1% of total isolates produced beta-lactamase. Penicillin and cefazolin worked well with beta-lactamase-nonproducing Prevotella but were remarkably affected by beta-lactamase-producing Prevotella. Cefmetazole, sulbactam/cefoperazone, and imipenem worked well against both types of Prevotella.

CONCLUSIONS

beta-lactams are still suitable for the first antimicrobial therapy in the treatment of these infections. However, because past beta-lactam administration increases the emergence of beta-lactamase-producing bacteria, beta-lactamase-stable antibiotics should be prescribed to patients with unresolved infections who have received beta-lactams.

[Transition of branched-chain amino acids and tyrosine ratio (BTR) in the blood of acute hepatitis patients]

The molar ratio of branched-chain amino acids to tyrosine (BTR) correlates well with the Fischer ratio, and can be measured in a short period of time. It is regarded as the method of analysis that will eventually replace the Fischer ratio. But clinical significance of BTR in terms of acute liver disorders has not been examined thoroughly as of yet. In this study, we measured BTR of 34 patients with acute hepatitis, and examined the transition of the acute period of acute hepatitis and its recovery process. Thirty-four patients diagnosed with acute viral hepatitis became subjects of examination (16 patients of A type, 15 patients of B type, 1 patient of C type, 2 patients of non-A, non-B, non-C type). Out of the 34 patients, 11 were in serious stages (HPT under 40%), including 3 in fulminant condition. By using preserved serum obtained during the acute period (within 1 week of the highest transaminase value), recovery period (within 4 weeks), and treatment period (3 months and later), measurements were conducted with Diacolor:BTR (enzymatic analysis, ONO Pharmaceutical Co., Ltd.), and the results were compared with those of 50 healthy subjects (25 men, 25 women). BTR correlated well with the Fischer ratio for chronic hepatic patients, and with albumin (Alb), PT, and ICGR15 as well, proving that it is useful as an indicator of hepatic reserve ability. But BTR has not been thoroughly examined as it relates to acute liver disorders. In this study, BTR fell in the acute period, correlating with the serious period, proving that it is a useful indicator. For acute liver damage, BTR supports conventional indicators (Alb, Ch-E, HGF, etc.) for assessing serious damage. Also, it has been suggested that measuring the passage of BTR could be the indicator of true recovery, including amino acid metabolism for liver disorders.

Ultraviolet-cured polymer microlens arrays

A method for fabricating microlens arrays that uses the contraction effect of UV-curable photopolymers is presented. Lenses with diameters ranging from 0.2 to 2 mm that were made under different conditions are optically evaluated. The optimum conditions for producing low f-number lenses are discussed.

Isolation and characterisation of neurotoxigenic Clostridium butyricum from soil in China

Soil specimens collected from a site around the home of patients with food-borne type E. botulism probably caused by neurotoxigenic Clostridium butyricum in Guanyun, Jiangsu province, China, were examined for the presence of neurotoxigenic C. butyricum. Five lakeside sites of Weishan lake, in an area near to the sites where the type E. botulism outbreaks caused by neurotoxigenic C. butyricum occurred were also surveyed. Type E toxin-producing C. butyricum was isolated from soil from four sites including the site in Guanyun. Polymerase chain reaction assay demonstrated the presence of the type E toxin gene in all the toxigenic isolates. The biochemical properties of the isolates from the Guanyun soil and the lakeside soil were identical except for inulin fermentation and starch hydrolysis properties. These results indicate that neurotoxigenic C. butyricum has its principal habitat in soil.

Laboratory diagnosis of toxigenic Clostridium difficile by polymerase chain reaction: presence of toxin genes and their stable expression in toxigenic isolates from Japanese individuals

Clostridium difficile causes pseudomembranous colitis and antibiotic-associated diarrhea. The definitive diagnosis of C. difficile infection is finally accomplished by the isolation of toxigenic C. difficile. However, only a small number of Japanese clinical laboratories are able to reach a definitive diagnosis of C. difficile infection, probably because simple reliable assays for toxins in the isolates are not available. In this study, we examined the compatibility of a polymerase chain reaction (PCR) assay and tissue culture assay to identify toxigenic C. difficile, in toxigenic and nontoxigenic C. difficile isolates from Japanese patients and healthy carriers. The specificity of PCR primers was demonstrated by restriction endonuclease digestion and seminested PCR in C. difficile VPI 10463 strain. No PCR product was amplified in the eight other clostridial species used to check the specificity of the PCR assay. The detection limit was 10(3) cells. Both toxin A and toxin B genes (the genes encoding the major virulence factors of C. difficile) were detected in 58 toxigenic C. difficile isolates, which showed a wide range of cytotoxic activity in tissue culture assays. Neither of the toxin genes was carried by 40 nontoxigenic strains of C. difficile. The results of this study strongly suggest that a definitive diagnosis of C. difficile infection can be accomplished by PCR detection of the toxin genes rather than by tissue culture assay of isolates.

Second site suppressor mutations of a GTPase-deficient G-protein alpha-subunit. Selective inhibition of Gbeta gamma-mediated signaling

G proteins transmit signals from cell surface receptors to intracellular effectors. The intensity of the signal is governed by the rates of GTP binding (leading to subunit dissociation) and hydrolysis. Mutants that cannot hydrolyze GTP (e.g. GsalphaQ227L, Gi2alphaQ205L) are constitutively activated and can lead to cell transformation and cancer. Here we have used a genetic screen to identify intragenic suppressors of a GTPase-deficient form of the Galpha in yeast, Gpa1(Q323L). Sequencing revealed second-site mutations in three conserved residues, K54E, R327S, and L353Delta (codon deletion). Each mutation alone results in a complete loss of the beta gamma-mediated mating response in yeast, indicating a dominant-negative mode of inhibition. Likewise, the corresponding mutations in a mammalian Gi2alpha (K46E, R209S, L235Delta) lead to inhibition of Gbeta gamma-mediated mitogen-activated protein (MAP) kinase phosphorylation in cultured cells. The most potent of these beta gamma inhibitors (R209S) has no effect on Gi2alpha-mediated regulation of adenylyl cyclase. Despite its impaired ability to release beta gamma, purified recombinant Gpa1(R327S) is fully competent to bind and hydrolyze GTP. These mutants will be useful for uncoupling Gbeta gamma- and Galpha-mediated signaling events in whole cells and animals. In addition, they serve as a model for drugs that could directly inhibit G protein activity and cell transformation.

Characterization of Clostridium botulinum type B neurotoxin associated with infant botulism in japan

The neurotoxin of strain 111 (111/NT) associated with type B infant botulism showed antigenic and biological properties different from that (Okra/NT) produced by a food-borne botulism-related strain, Okra. The specific toxicity of 111/NT was found to be about 10 times lower than that of Okra/NT. The monoclonal antibodies recognizing the light chain cross-reacted with both neurotoxins, whereas most of the antibodies recognizing the carboxyl-terminal half of the heavy chain of Okra/NT did not react to 111/NT. Binding experiments with rat brain synaptosomes revealed that 125I-labeled 111/NT bound to a single binding site with a dissociation constant (Kd) of 2.5 nM; the value was rather lower than that (0.42 nM) of 125I-Okra/NT for the high-affinity binding site. In the lipid vesicles reconstituted with ganglioside GT1b, 125I-Okra/NT interacted with the amino-terminal domain of synaptotagmin 1 (Stg1N) or synaptotagmin 2 (Stg2N), fused with the maltose-binding protein, in the same manner as the respective full-length synaptotagmins, and the Kd values accorded with those of the low- and high-affinity binding sites in synaptosomes. However, 125I-111/NT only exhibited a low capacity for binding to the lipid vesicles containing Stg2N, but not Stg1N, in the presence of ganglioside GT1b. Moreover, synaptobrevin-2, an intracellular target protein, was digested to the same extent by the light chains of both neurotoxins in a concentration-dependent manner. These findings indicate that the 111/NT molecule possesses the receptor-recognition site structurally different from Okra/NT, probably causing a decreased specific toxicity.

Inhibition of enhanced toxin production by Clostridium difficile in biotin-limited conditions

Production of toxins A and B by Clostridium difficile is enhanced in a defined medium with biotin-limited conditions. In the present study compounds inhibitory to enhanced toxin production by a C. difficile strain were examined. Increases in biotin concentration from 0.05 nM to 50 nM accelerated growth and inhibited enhanced toxin production. Asparagine, glutamic acid and glutamine (10 mM) showed an effect on growth and toxin production similar to that of biotin. Lysine (10 mM) suppressed growth and inhibited toxin production. Addition of these toxin-inhibitory compounds within an incubation period of 2 days inhibited the enhanced toxin production, but later addition showed only slight inhibition of toxin production. Amino acids contained in the defined medium under the biotin-limited conditions were actively utilised in the presence of the three toxin-inhibitory amino acids, but in the presence of lysine, amino-acid utilisation was suppressed. Different mechanisms of action of these toxin-inhibitory molecules, which may be divided into excess biotin, asparagine-glutamic acid-glutamine group, and lysine, are discussed.

Effect of isoleucine on toxin production by Clostridium difficile in a defined medium

Supplementation of a carbohydrate-free minimal medium with a high level (100 mM) of histidine, methionine, valine, isoleucine, proline and leucine, in particular isoleucine, markedly increased toxin production by Clostridium difficile VPI 10463. The effect of isoleucine was further examined. Increasing the concentration of isoleucine from 20 to 100 mM remarkably increased toxin production, while bacterial growth decreased gradually. Amino acid analysis of the culture revealed that, at 100 mM isoleucine, consumption of isoleucine was remarkably increased. During the incubation period when toxin titers increased markedly but bacterial growth was declining, isoleucine, leucine and cysteine were taken up preferentially and alanine and cystathionine, which were not found at 1 mM isoleucine, were produced in large quantities. These findings suggest that isoleucine may play an important role in toxin production by C. difficile and that alanine and cystathionine production may be co-regulated with the toxin production in the absence of fermentable carbohydrates.

Cardiovascular effect of a new 1,5-benzothiazepine derivative TA-993 in anesthetized dogs

TA-993 is a new 1,5-benzothiazepine derivative having l-cis configuration and shows a potent antiplatelet aggregating action. We studied its cardiovascular effect in anesthetized dogs by using diltiazem as a reference compound. TA-993 (> or = 10 microg/kg, i.v.) significantly increased blood flows of common carotid, brachial, and femoral arteries. The peak of its effect was observed approximately 60 min after the administration, and the peak level was maintained until > or = 300 min after the administration. TA-993 (100 microg/kg, i.v.) slightly increased cardiac output in the same manner. However, TA-993 did not cause any persistent effects on arterial pressure, LVdP/dtmax, or vertebral, coronary, superior mesenteric, and renal blood flows. TA-993 caused concentration-dependent vasorelaxation in the isolated canine femoral artery contracted with 40 mM K+, but its potency was approximately 1/20 that of diltiazem. The increasing action of TA-993 on femoral blood flow was completely inhibited by pretreatment with hexamethonium in anesthetized dogs. These results indicate that TA-993 has a selective increasing action on common carotid, brachial, and femoral blood flows and suggest that the action is mediated by the autonomic nervous system.

Effect of arginine on toxin production by Clostridium difficile in defined medium

Twenty strains of Clostridium difficile were examined for the effect of arginine on toxin production in a defined medium. In three strains, the production of toxins A and B was greatly enhanced in the absence of arginine. These strains showed distinctively poorer growth in the absence of arginine in comparison with the remaining 17 strains, indicating that the presence of arginine is required for good growth among the three strains. From the present results, test strains were divided into two groups: a group in which arginine insufficiency caused distinctly poor growth and enhanced toxin production, and another group in which there was neither distinctly poor growth nor enhanced toxin production. The phenomenon is discussed in relation to the biosynthesis and catabolism of arginine.

Association between frequency of amino acid changes in core region of hepatitis B virus (HBV) and the presence of precore mutation in Japanese HBV carriers

To elucidate the relationship between the frequency of core mutations and precore mutation of hepatitis B virus (HBV) in Japanese HBV carriers, we investigated the nucleotide sequence of the precore/core region of HBV in 26 Japanese HBV carriers [15 who were HBe antigen-negative (HBeAg-) and 11 who were HBeAg-positive (HBeAg+)]. The number of amino acid changes (5.9 +/- 3.8) in the core region of HBV in HBeAg-carriers was significantly greater than that in the HBeAg+ carriers (1.5 +/- 1.0; P < 0.005). The precore stop codon mutation was found in 93.3% of HBeAg-negative HBV carriers, while no precore mutation was found in the HBeAg-positive HBV carriers, suggesting that the frequency of core mutations may be associated with the presence of the precore stop codon mutation. However, there was no significant difference in the frequency of amino acid changes among HBeAg-HBV carriers. The mean number of core amino acid changes of liver cirrhosis patients, chronic active hepatitis patients, chronic persistent hepatitis patients, and asymptomatic carriers were 2.7 +/- 1.5, 6.0 +/- 2.2, 4.7 +/- 1.2, and 8.4 +/- 5.3, respectively. We detected hot spots for core mutations, which showed characteristic localizations and specific substitutions: Gly-87, Leu-97, and Thr-130 were detected exclusively in patients with chronic liver disease with or without HBeAg. To address further the relationship between frequency of core mutations and the presence of the precore stop codon mutation, we investigated the precore/core nucleotide sequence serially along with seroconversion in three patients with chronic hepatitis B in whom the hepatitis either became inactive or remained active after the seroconversion. Emergence of the precore stop codon mutation and a significant increase in core amino-acid changes after seroconversion were noted in all three patients. Our results suggest a close association between the frequency of core amino acid changes and the presence of the precore stop codon mutation; some characteristic core mutations may be associated with the clinical course of chronic hepatitis B in Japanese patients.

Characterization of a neurotoxigenic Clostridium butyricum strain isolated from the food implicated in an outbreak of food-borne type E botulism

Neurotoxigenic Clostridium butyricum was isolated from the food implicated in an outbreak of clinically diagnosed type E botulism in China. PCR assay showed that the isolate (LCL 155) contained the type E botulinum toxin gene. This appears to be the first report of neurotoxigenic C. butyricum causing food-borne botulism.

Emergence of Clostridium botulinum type B-like nontoxigenic organisms in a patient with type B infant botulism

We encountered a patient with infant botulism caused by a single clone of Clostridium botulinum type B. In the early convalescent phase, a C. botulinum type B-like nontoxigenic organism emerged in the feces instead. Growth inhibition of toxigenic strains by nontoxigenic strains was examined.

Emergence of rifampin-resistant Rhodococcus equi in an infected foal

To investigate the emergence of rifampin resistance in Rhodococcus equi strains isolated from foals and their environment in Japan, we compared the in vitro antimicrobial susceptibilities to rifampin of 640 isolates from 64 infected foals and 98 soil isolates from their horse-breeding farms. As a control, 39 human isolates from patients with and without AIDS were also tested for susceptibility to rifampin. All of the isolates showed rifampin sensitivity, except isolates from one infected foal and two patients with AIDS that showed rifampin resistance. To investigate the emergence of rifampin-resistant R. equi in the infected foal, which had received rifampin monotherapy for a month before euthanasia, 99 isolates of R. equi from the lesions and 20 isolates from the intestinal contents of the one foal with rifampin-resistant organisms were analyzed for rifampin susceptibilities, pathogenicities, and ribotypes. Of the 99 isolates from the lesions, all of which were virulent R. equi strains containing a virulence plasmid with a size of 85 or 90 kb, 90 (91%) isolates were rifampin resistant (MIC, > or = 12.5 microg/ml). On the other hand, of the 20 isolates from the intestinal contents, 11 (55%) isolates showed rifampin resistance (MIC, > or = 25 microg/ml), and 5 of them were avirulent R. equi strains. Among these 101 rifampin-resistant R. equi isolates with and without virulence plasmids characterized by ribotyping, 58 were type I, 20 were type II, 11 were type III, and 12 were type IV. These results demonstrated that at least eight different rifampin-resistant R. equi strains emerged concurrently and respectively from the different lesions and intestinal contents of the infected foal.

Possible involvement of ATP-dependent K-channel related mechanisms in the antihypertensive and cough suppressant effects of the novel ACE inhibitor (2S, 3aS, 7aS)-1-(N2-nicotinoyl-L-lysyl-gamma-D-glutamyl)octahydro-1H- indole-2-carboxylic acid

The antihypertensive and cough suppressant mechanisms of DU-1777 ((2S,3aS,7aS)-1-(N2-nicotinoyl-L-lsyl-gamma-D-glutamyl )octahydro-1H-indole-2 -carboxylic acid, CAS 116662-73-8), a new long-acting angiotensin-1-converting enzyme (ACE) inhibitor, were investigated in vivo and in vitro. The antihypertensive effects of DU-1777 at 10 mg/kg p.o. and cromakalim at 0.3 mg/kg p.o. were partially (about 60%) or fully antagonized by glibenclamide at 10 mg/kg i.v. in 2-kidney, 1-clip renal hypertensive rats (2K-1C RHR). The antihypertensive effects of a Ca blocker (nifedipine) and other ACE inhibitors (captopril, alacepril, enalapril, lisinopril, imidapril and quanapril) were not antagonized by glibenclamide. In deoxycorticosterone acetate-salt hypertensive rats (DOCA-HR), the antihypertensive effects of DU-1777 at 3-30 mg/kg p.o. were fully antagonized by glibenclamide. However, in vitro, DU-1777 (10(-6)-10(-3) mol/l) did not affect aortic ring contractions induced by high K (30 mmol/l). In guinea pig, citric acid induced cough was increased by ACE inhibitors, captopril, alacepril, enalapril and lisinopril (10 and 30 mg/kg p.o.). DU-1777 had a tendency to decrease citric acid induced cough and the effect was antagonized by glibenclamide. These results suggest that while DU-1777 itself does not open ATP-dependent K channel, it indirectly produces these effects through unknown mechanisms in vivo. Moreover, these effects contributed to the antihypertensive effect in DOCA-HR and cough suppressant effect in guinea pigs.

Human gene encoding CD38 (ADP-ribosyl cyclase/cyclic ADP-ribose hydrolase): organization, nucleotide sequence and alternative splicing

We have recently demonstrated that cyclic ADP-ribose (cADPR) serves as a second messenger for glucose-induced insulin secretion [Takasawa et al. (1993a) Science 259, 370-373] and that CD38 has both ADP-ribosyl cyclase (ADRC) and cADPR hydrolase activities [Takasawa et al. (1993b) J. Biol. Chem. 268, 26052-26054]. In this study, we determined the structure of the human CD38 gene, and showed that two mRNA forms originated by alternative splicing from the CD38 gene. The human CD38 gene consists of 8 exons that extend more than 77 kb on the human genome. Exon 1 encoded the 5'-untranslated region of the mRNA, the N-terminal end of CD38 and the putative transmembrane domain, and exon 2-8 encoded the remainder of CD38: the exon-intron organization of the human CD38 gene is similar to that of the Aplysia ADRC gene [Nata et al. (1995) Gene 158, 213-218]. This structural conservation between human and Aplysia genes suggests that both genes may have evolved from a common ancestral gene.

Typing of verotoxins by DNA colony hybridization with poly- and oligonucleotide probes, a bead-enzyme-linked immunosorbent assay, and polymerase chain reaction

To identify the type of Verotoxins (VT) produced by Verocytotoxin-producing Escherichia coli (VTEC), a sensitive bead-enzyme-linked immunosorbent assay and polymerase chain reaction with common and specific primers to various VTs (VT1, VT2, VT2vha, VT2vhb, and VT2vp1) were developed. Together with colony hybridization tests with oligo- and polynucleotide probes, these methods were applied to VTEC isolates to type the VT produced. The toxin types of 26 of 37 strains were identified, but the reaction profiles in assays of the remaining 11 strains suggested the existence of new VT2 variants. The application of these identification procedures may be useful as a tool for clinical and epidemiological studies of VTEC infection.

Enhancement of Clostridium difficile toxin production in biotin-limited conditions

The effect of biotin on toxin production by Clostridium difficile was examined in a defined medium. When toxin production by strain KZ 1647, which was isolated from a healthy adult, was examined in relation to its biotin requirement, it was found that with decreasing concentrations of biotin, bacterial growth was decreased, but production of both toxins A and B were remarkably increased, particularly with 0.05 nM biotin. The time course of production of both toxins in biotin-limited conditions was similar to that in biotin-enriched conditions. The biotin effect on toxin production was also observed in 15 other strains, suggesting that the effect occurs frequently amongst toxigenic C. difficile strains. The biotin effect is discussed in relation to the pathogenesis of C. difficile colitis.

Long-lasting antagonistic effects of monatepil on Ca2+ current in guinea-pig ventricular cells

Monatepil maleate (CAS 103377-41-9, AJ-2615), a new derivative of dihydrodibenzothiepins, showed dose-dependent inhibition of Ca2+ current (ICa) in single cardiac cells isolated from guinea-pig ventricle. ICa was elicited by depolarization from -40 mV to +10 mV at 0.2 Hz. IC50 value of monatepil for the peak ICa at +10 mV was 18.7 nmol/l. The ICa inhibition was still sustained 30 min after washout, indicating that monatepil had long lasting activity in the mammalian single muscle cell.