Aerodynamic damping during rapid flight maneuvers in the fruit fly Drosophila

We systematically investigated the effect of body rotation on the aerodynamic torque generation on flapping wings during fast turning maneuvers (body saccades) in the fruit fly Drosophila. A quasi-steady aerodynamic simulation of turning maneuvers with symmetrically flapping wings showed that body rotation causes a substantial aerodynamic counter-torque, known as flapping counter-torque (FCT), which acts in the opposite direction to turning. Simulation results further indicate that FCTs are linearly dependent on the rotational velocity and the flapping frequency regardless of the kinematics of wing motion. We estimated the damping coefficients for the principal rotation axes - roll, pitch, yaw - in the stroke plane frame. FCT-induced passive damping exists about all the rotation axes examined, suggesting that the effects of body rotation cannot be ignored in the analysis of free-flight dynamics. Force measurements on a dynamically scaled robotic wing undergoing realistic saccade kinematics showed that although passive aerodynamic damping due to FCT can account for a large part of the deceleration during saccades, active yaw torque from asymmetric wing motion is required to terminate body rotation. In addition, we calculated the mean value of the damping coefficient at 21.00 x10(-12) N m s based on free-flight data of saccades, which is somewhat lower than that estimated by the simulation results (26.84 x 10(-12) N m s).

Impaired angiogenesis in aging myocardial microvascular endothelial cells is associated with reduced importin alpha and decreased nuclear transport of HIF1 alpha: mechanistic implications

Aging is associated with increased incidence of myocardial infarctions and impaired angiogenesis - new capillary blood vessel formation from preexisting vessels. The molecular mechanism(s) of aging-related impairment of angiogenesis are unknown. In the present study we focused on the mechanism of activation of the gene for vascular endothelial growth factor (VEGF - the most potent stimulator of angiogenesis) in young and aging myocardial microvascular endothelial cells (MMEC). Activation of VEGF gene in the cell nucleus is mediated in part by the transcription factor hypoxia-inducible factor 1 alpha (HIF1 alpha). In order to activate VEGF gene, HIF1 alpha must first be transported to the nucleus, but the mechanisms of this transport are unknown. We hypothesized that reduced VEGF gene activation and impaired angiogenesis in myocardium during aging can result from downregulation of the nuclear transport receptor - importin alpha that leads to decreased transport of HIF1 alpha to the nucleus. We examined in MMEC isolated from young (3 months of age) and aging (24 months old) Fisher F-344 rats: 1) in vitro angiogenesis; and 2) the expression of VEGF, importin alpha and HIF1 alpha. Aging MMEC exhibited a 3.7-fold reduction in angiogenesis and a corresponding reduction in VEGF (by 3-fold) and importin alpha (by 1.9-fold) levels compared to young MMEC. Aging MMEC also exhibited cytoplasmic accumulation (by 1.8-fold) of HIF1 alpha protein, reduced HIF1 alpha transport to the nucleus and decreased binding of HIF1 alpha protein to the VEGF gene promoter. This study is the first demonstration of the downregulation of importin alpha in aging MMEC and reduced nuclear transport of HIF1 alpha, which likely lead to decreased VEGF gene activation and impaired angiogenesis.

Comparison of three current sources for single-electrode capacitance measurement

The capacitance of a single electrode is usually measured by injecting a current to the electrode and measuring the resultant voltage on the electrode. In this case, a voltage-controlled current source with a high bandwidth is needed because the impedance is inversely proportional to the excitation frequency. In this design note, three different current sources are discussed: (1) the Howland current source, (2) a modified Howland current source, and (3) a dual op-amp current source. The principle and dynamic performances are presented and compared. Simulation and experimental results show that although the Howland current source has the lowest (i.e., worst) output impedance, its output is the most stable among the three current sources when the frequency changes. Therefore, it is suitable for single-electrode capacitance measurement. Initial tests have proven the feasibility of single-electrode capacitance sensor with the Howland current source.

Hepatocyte nuclear factor 4alpha attenuates hepatic fibrosis in rats

BACKGROUND AND AIMS

Hepatocyte nuclear factor 4alpha (HNF4alpha) is a central transcriptional regulator of hepatocyte differentiation and function. The aim of this study was to evaluate the effect of HNF4alpha on attenuation of hepatic fibrosis.

METHODS

The adenoviruses carrying HNF4alpha gene or containing siRNA targeting HNF4alpha were injected through tail vein on two distinct hepatic fibrosis models either induced by dimethylnitrosamine or by bile duct ligation in rats. Moreover, HNF4alpha, epithelial-mesenchymal transition (EMT)-related and fibrotic markers in hepatocytes, hepatic stellate cells (HSCs) and liver tissues were detected by real time PCR, immunofluorescence or immunohistochemistry.

RESULTS

We demonstrated that decreased expression of HNF4alpha and epithelial markers accompanied by enhanced expression of mesenchymal markers occurred in fibrotic liver. More importantly, forced expression of HNF4alpha remarkably alleviated hepatic fibrosis and improved liver function with suppression of EMT in both fibrosis models. In contrast, downregulation of HNF4alpha by siRNA aggravated hepatic fibrosis and decreased the expression of E-cadherin in association with the enhanced expression of vimentin and fibroblast-specific protein-1. In vitro study revealed that HNF4alpha could suppress the EMT process of hepatocytes induced by transforming growth factor-beta1 and increase the expression of liver-specific genes. A similar phenomenon of the EMT process was observed during the activation of HSCs, which was abrogated by HNF4alpha. Additionally, HNF4alpha deactivated the myofibroblasts through inducing the mesenchymal-to-epithelial transition and inhibited their proliferation.

CONCLUSIONS

Our study suggests that HNF4alpha is critical for hepatic fibrogenesis and upregulation of HNF4alpha might present as an ideal option for the treatment of hepatic fibrosis.

Simulating the ES-SAGD Process With Solvent Mixture in Athabasca Reservoirs

Abstract

The ES-SAGD process was developed to improve the energy and oil drainage efficiency of the SAGD process. The idea of the ES-SAGD process is to co-inject solvent with steam and the co-injected solvent mixes with the bitumen to further reduce the viscosity of the heated bitumen along the boundary of the steam chamber thus enhances the oil recovery. Practically, the co-injected solvent will be a solvent mixture (such as diluent /naphtha) because of its availability and reduced cost than a pure hydrocarbon. This paper reports the results of an ES-SAGD lab test conducted with steam and diluent co-injection using Athabasca bitumen. To simulate the ES-SAGD test, a pseudo-component scheme to represent the complex solvent mixture in the numerical model is derived, based on the diluent composition and measured PVT data. The behaviours and effects of the co-injected solvent in the ES-SAGD process are analyzed through detailed history matching of the ES-SAGD test. Numerical sensitivity analyses are also performed to investigate the effects of some key parameters in the numerical approach.

Introduction

The Steam Assisted Gravity Drainage (SAGD)(1) and the Vapour Extraction (VAPEX)(2), combined with the horizontal well technology, are being developed to recover the enormous heavy oil and bitumen resources in Western Canada. The SAGD process has been successfully field-tested and is in the early stage of commercial-scale application, while the VAPEX process is still at the piloting stage. Both processes have their advantages and disadvantages. The advantage of the SAGD process is its high oil production rate. However, the high production rate of the SAGD process is associated with intensive energy consumption and CO2 emissions from burning natural gas to generate steam, and costly post-production water treatment. The VAPEX process, on the other hand, has the advantage of lower energy consumption and water usage, and therefore less CO2 emission and water treatment cost. However, the major drawbacks of the VAPEX process are its relatively lower oil production rate and the additional cost of solvent.

Selective Effects of Glucose, Insulin and Leptin by Molecular Breast Cancer Subtype

Background: Type II diabetes and obesity are important risk factors for post-menopausal luminal A (LA) and triple negative (TN) pre-menopausal breast cancers, particularly in African American (AA) and Hispanic women. Breast cancer patients with these chronic metabolic diseases also have a worse prognosis, independent of other factors. We have published that metformin inhibits cell growth (S phase arrest) and induces apoptosis, only in TN cell lines in vivo and in vitro. It is less active, growth inhibitory (G1 arrest) and does not induce apoptosis in other breast cancer cell subtypes (Cell Cycle, 2009).Methods: We investigated the effects of glucose as a mitogen at physiologic (5mM), metabolic syndrome (7mM) or diabetic levels (10mM), with or without insulin (100 ng/ml) or leptin (100 ng/ml) using cell lines representing all molecular subtypes of breast cancer. Metformin was then used in combination with the above, to determine whether it would block the mitogenic or signaling effects of supraphysiological glucose, insulin or leptin.Results: The LA (MCF-7) and 2 of 5 TN cell lines (derived from AA patients; HCC 1806 and MDA 468) showed the most cell growth in response to glucose >5mM (75% for MCF-7, 30-50% for AA TN lines). Three TN cell lines from Caucasians (MDA231, HCC1937, BT20), the HER2 (SKBR3) and luminal B (BT-474) cells showed less growth induction with glucose >5mM. In TN lines only, glucose associated mitogenesis was associated with increased EGFR, pEGFR, IGF1R, pIGF1R, AKT and pAKT and decreases in AMPK, pAMPK, p38, IRS2, and the cyclins D1, E and A in a dose dependent manner. Metformin abrogated glucose induced cell growth and the aforementioned protein expression/phosphorylation changes involving EGFR, IGF1R, and AKT, increased AMPK and pAMPK and induced a profound reduction in Cyclin D1 across all glucose concentrations in TN cell lines from AA women. It reduced but did not eliminate glucose associated mitogenesis in the TN cell lines from Caucasian patients. Metformin had a more variable effect on cell lines of other molecular subtypes grown under high glucose conditions. The 5 TN breast cancer cell lines were uniformly resistant to both leptin and insulin associated mitogenesis, across a wide range of glucose concentrations. In contrast, both leptin and insulin significantly promoted LA breast cancer cell growth. These effects were resistant to metformin treatment. Leptin and insulin had the least growth promoting effects on HER2 breast cancer cell lines, whereas they induced modest growth induction in LB cell lines.Conclusions: All TN cell lines showed significant mitogenesis in response to glucose >5mM, whereas they were uniformly resistant to both leptin and insulin. The glucose associated mitogenesis was more pronounced in lines derived from AA patients, as were the anti-mitgenic effects of metformin. LA cells showed marked growth induction by glucose, leptin and insulin, whereas HER2 cell lines showed general resistance to all of these factors. These data suggest that metabolic and hormonal shifts with obesity and diabetes, as well as metformin response vary by the molecular subtype of breast cancer cells and ethnicity.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5154.

A role for a cell wall localized glycine-rich protein in dehydration and rehydration of the resurrection plant Boea hygrometrica

The acquisition of desiccation tolerance in dicotyledonous angiosperms requires the induction of a co-ordinated programme of genetic and biochemical processes during drying and the adaptive mechanisms are primarily protoplasmic in nature. Recent studies have shown that changes in cell wall structure and composition are also important for recovery after drying, however, the molecular mechanisms that underpin these adaptive responses are largely unknown. Here, the desiccation-tolerant plant Boea hygrometrica was used as a model system to investigate the changes in gene expression and cell wall adaptation that take place during extreme dehydration. A cDNA macroarry analysis of dehydration-inducible genes led to the identification of a gene encoding a glycine-rich protein (BhGRP1). The corresponding transcript was up-regulated during drying in B. hygrometrica leaves. In silico analysis revealed that BhGRP1 is targeted to the cell wall and this was confirmed in planta. Morphological changes in the cell wall architecture were also observed during the process of drying and re-watering. Concomitant with this observation, cell wall profiling by Fourier transform infrared spectroscopy indicated that protein levels increased upon desiccation and remained broadly similar upon re-watering. These findings suggest that the deposition of BhGRP1 may play a role in cell wall maintenance and repair during dehydration and rehydration in B. hygrometrica.

A single high dose of methamphetamine increases cocaine self-administration by depletion of striatal dopamine in rats

Psychostimulant addicts often take high doses of drugs, and high doses of psychostimulants such as methamphetamine (METH) are neurotoxic to striatal dopamine (DA) terminals. Yet, the effects of high doses of METH on drug-seeking and drug-taking behavior have not been examined. In the present study, we found that single high doses of METH in rats (10-20 mg/kg) dose-dependently increased cocaine self-administration under fixed-ratio 2 (FR2) reinforcement conditions, while higher doses (40 mg/kgx1 or 10 mg/kg/2 hx4) caused high mortality among rats maintained on daily cocaine self-administration. The increased cocaine self-administration appeared to be a compensatory response to reduced cocaine reward after METH, because the same doses of METH caused a dose-dependent reduction both in "break-point" levels for cocaine self-administration under progressive-ratio reinforcement and in nucleus accumbens DA response to acute cocaine. Further, METH (10-20 mg/kg) produced large DA release (4000%-6000% over baseline), followed by a significant reduction in striatal DA and 3,4-dihydroxyphenylacetic acid (DOPAC) contents, but without significant changes in striatal DA transporter levels. These findings suggest that the present high doses of METH caused striatal DA depletion or hypofunction without severe damage in DA terminals, which may contribute to the increased cocaine-taking behavior observed in the present study. Provided that the present doses of METH may mimic METH overdose incidents in humans, the present findings suggest that METH-induced DA depletion or neurotoxicity may lead to an increase in subsequent drug-taking and drug-seeking behavior.

Reduced ghrelin in endothelial cells plays important mechanistic role in aging-related impairment of angiogenesis

Ghrelin, a hormone produced mainly by gastric mucosal cells stimulates growth hormone (GH) release. Ghrelin is also expressed in the endothelial cells of blood vessels suggesting its physiological role and a function in these cells. We recently demonstrated that ghrelin induces angiogenesis--new capillary blood vessel formation- in neonatal human microvascular endothelial cells (HMVECs). Angiogenesis is impaired in aging individuals both in vitro and in vivo, but the precise mechanism(s) of this phenomenon is unknown. We examined whether HMVECs derived from aging individuals (66 years and 90 years old), 66-HMVECs and 90-HMVECs have reduced ghrelin levels vs. neonatal (Neo) HMVECs and whether treatment with exogenous ghrelin can restore impaired in vitro angiogenesis on matrigel in aged HMVECs. Ghrelin levels were reduced in the aged HMVECs by 3.2-fold (p<0.05) compared to Neo-HMVECs. Angiogenesis was significantly decreased in the aged 66- and 90-HMVECs by 39.7% (p = 0.003) and 62.4% (p = 0.003), respectively compared to Neo-HMVECs. Treatment with exogenous ghrelin significantly reversed impaired angiogenesis in aged HMVECs with the EC(50) 0.05 nM. Ghrelin induced angiogenesis in Neo-HMVECs mainly through ERK2 activation. This study is the first demonstration that reduced ghrelin is one of the factors responsible for aging-related impairment of angiogenesis.

Phase II study of postoperative chemoradiotherapy for esophageal carcinoma

e15606

Background: Esophageal squamous cell carcinoma is still a virulent disease diagnosed at late stage and remains a major cause of carcinoma mortality in China. The preoperative chemoradiotherapy had been applied to patients with esophageal carcinoma in an effort to reduce the relapse and improve survival. However, randomized controlled trails have shown conflicting results. Intergroup study 0116 demonstrated that postoperative chemoradiotherapy significantly improved overall survival in gastric carcinoma patients. The question remains whether postoperative chemoradiotherapy can improve overall survival in patients with esophageal carcinoma. Our planning study was to investigate the role of postoperative chemoradiotherapy in the multimodality treatment for locally advanced esophageal carcinoma. Methods: From October 2000 to October 2007, Fifty-two patients who underwent esophagectomy with stage II-III esophageal carcinoma were enrolled. All patients received 50Gy of postoperative radiotherapy over 25 fractions in 5 weeks. Two cycles of chemotherapy (Paclitaxel 135mg/m2 d1,cisplatin 20mg/m2d1–3) were administered concurrently on days 1–3 and days 29–31 of radiotherapy. Results: Of the total 52 patients, 28 (54%) developed grade 3 or 4 toxicity.At the time of analysis, 23 patients died. The median follow-up for surviving patients was 23.5 months. The median survival time was 37.2 months. Incidences of tumor recurrence were 53.8 % (28/52) of patients. As expected, distant metastasis was predominant. The 2-year local-regional control survival, distant metastasis-free survival and relapse-free survival were 60.01%, 71.38% and 42.01%, respectively. 1-year and 3-year overall survival were 82.19% and 47.13%, respectively. Conclusions: This novel postoperative chemoradiation regimen for treatment of patients with stage II-III esophageal cancer has a tolerable toxicity and promising 3-year overall survival.

No significant financial relationships to disclose.

[Establishment of a rabbit model of Acanthamoeba keratitis]

AIM

To establish an animal model of Acanthamoeba keratitis.

METHODS

Six New Zealand white rabbits were each injected intrastromally with Acanthamoeba suspension 3 days after subconjunctival injection with dexamethasone.

RESULTS

All of the 6 rabbits developed keratitis. Acanthamoeba protozoa were identified by the methods of corneal scraping with 10% potassium hydroxide wet mount examined under microscope, corneal protozoa culture and pathological section examination.

CONCLUSION

A rabbit model of Acanthamoeba keratitis was established.

A major QTL for acute ethanol sensitivity in the alcohol tolerant and non-tolerant selected rat lines

The Alcohol Tolerant and Alcohol Non-Tolerant rats (AT, ANT) were selectively bred for ethanol-induced ataxia as measured on the inclined plane. Here we report on a quantitative trait locus (QTL) study in an F(2) intercross population derived from inbred AT and ANT (IAT, IANT) and a follow-up study of congenics that were bred to examine one of the mapped QTLs. Over 1200 F(2) offspring were tested for inclined plane sensitivity, acute tolerance on the inclined plane, duration of the loss of righting reflex (LORR) and blood ethanol at regain of the righting reflex (BECRR). F(2) rats that were in the upper and lower 20% for inclined plane sensitivity were genotyped with 78 SSLP markers. Significant QTLs for inclined plane sensitivity were mapped on chromosomes 8 and 20; suggestive QTLs were mapped on chromosomes 1, 2 and 3. Highly significant QTLs for LORR duration (LOD = 12.4) and BECRR (LOD = 5.7) were mapped to the same locus on chromosome 1. Breeding and testing of reciprocal congenic lines confirmed the chromosome 1 LORR/BECRR QTL. A series of recombinant congenic sub-lines were bred to fine-map this QTL. Current results have narrowed the QTL to an interval of between 5 and 20 Mb. We expect to be able to narrow the interval to less than 5 Mb with additional genotyping and continued breeding of recombinant sub-congenic lines.

A phytoplasma related to 'Candidatus phytoplasma asteri' detected in citrus showing Huanglongbing (yellow shoot disease) symptoms in Guangdong, P. R. China

Citrus huanglongbing (HLB) or yellow shoot disease (i.e., greening disease) is highly destructive to citrus production worldwide. Understanding the etiology of HLB is critical for managing the disease. HLB is currently associated with infection by 'Candidatus Liberibacter spp.' around the world, including China. However, Koch's postulates have not been fulfilled. In addition, other plant pathogens also may be involved in HLB. In a survey performed in Guangdong Province, P. R. China in 2006 and 2007, 141 citrus samples showing typical symptoms of HLB from 11 different cities were collected. Polymerase chain reaction (PCR) using phytoplasma-specific primer sets fU5/rU3 nested with primer set P1/P7 identified 110 (78.0%) positive samples. A 1,785-bp amplicon was obtained with primer set P1/P7. Analysis showed a 100% identity of this sequence in the region of 16S rDNA and 16S-23S rRNA intergenic transcribed spacer to three strains of 'Candidatus Phytoplasma asteri' (onion yellows [Japan], aster yellows 'watercress' [Hawaii], and valeriana yellows [Lithuania]). Of the 141 samples, 89 (63.1%) samples were positive for 'Ca. Liberibacter asiaticus'. When mixed infection was considered, 69 (48.9%) samples were positive for both 'Ca. P. asteri' and 'Ca. L. asiaticus'. Transmission electron microscopy (TEM) showed low titers of both walled and wall-less bodies in the phloem sieve tubes of HLB citrus. When transmission from symptomatic citrus to periwinkle (Catharanthus roseus) via dodder (Cuscuta campestris) was conducted, both phytoplasma and 'Ca. L. asiaticus' were detected from the affected periwinkle. In addition to yellowing/mottling, the infected periwinkle showed symptoms of virescence and phyllody which are commonly associated with phytoplasmal diseases. TEM analysis of affected periwinkle revealed pleomorphic and wall-less organisms, characteristic of phytoplasmas, filling some phloem sieve tubes. In contrast, walled bacteria were at low titer. This study showed that in addition to 'Ca. L. asiaticus', a phytoplasma related to 'Ca. P. asteri' could also be detected in citrus showing HLB symptoms in Guangdong.

[Effects of hydroxy safflor yellow A on blood vessel and mRNA expression with VEGF and bFGF of transplantation tumor with gastric adenocarcinoma cell line BGC-823 in nude mice]

OBJECTIVE

To investigate the effects of Hydroxy Safflor yellow A (HSYA) on the growth of blood vessel of transplantation tumor of gastric adenocarcinoma cell line BGC-823 in nude mice and its underlying mechanism of antagonizing tumor angiogenesis.

METHOD

The BGC-823 cells was subcutaneouly injected into the right anterior armpit of BALB/C nu/nu nude mice and established the animal model of transplantation tumor. Then nude mice were divided into 4 groups at random: model group, control group, high or low dosage of HSYA group. The model group were treated with normal sodium by intraperitoneal injection, HSYA groups were treated with HSYA at concentration of 0.056 g x L(-1) and 0.028 g x L(-1) by intraperitoneal injection, and in these groups each mouse was injected 2 times everyday with 0.2 mL by 4-6 hours interval. The control group were injected in enterocoelia 1 times every 2 days starting from the third day with cytoxan at 2 g x L(-1). 20 days later, the volume and weight of nude mice were observed. The pathological change of tumor tissue was observed under optical microscope. The mRNA expression of VEGF and bFGF of transplantation tumor were detected by real time quantitative PCR.

RESULT

The volume (607.42 +/- 252.96) mm3, weight (0.88 +/- 0.14) g of transplantation tumor, the mRNA expression level of VEGF 0.49 +/- 0.13 and bFGF 0.60 +/- 0.48 are reduced significantly after treatment with HSYA at the concentration of 0.028 g x L(-1) compared with physiologic saline-treated group (P < 0.05 or P < 0.01). The tumor pathological angiogenesis of HSYA group is also less obvious than the normal sodium-treated group.

CONCLUSION

HSYA in given concentration can inhibit the growth of BGC-823 transplantation tumor, and decreasing the mRNA expression of VEGF and bFGF, which suggests that inhibiting tumor angiogenesis may be one of the mechanisms of HSYA antagonizing tumor.

TGF-beta repression of Id2 induces apoptosis in gut epithelial cells

Transforming growth factor-beta (TGF-beta) regulates epithelial tissue homeostasis by activating processes that control cell cycle arrest, differentiation and apoptosis. Disruption of the TGF-beta signaling pathway often occurs in colorectal cancers. Earlier, we have shown that TGF-beta induces apoptosis through the transcription factor Smad3. Affymetrix oligonucleotide microarrays were used to identify TGF-beta/Smad3 target genes that regulate apoptosis in rat intestinal epithelial cells (RIE-1). We found that TGF-beta repressed the expression of the inhibitor of differentiation (Id) gene family. Knockdown of Id1 and Id2 gene expression induced apoptosis in RIE-1 cells, whereas overexpression of Id2 attenuated TGF-beta-induced apoptosis. TranSignal Protein/DNA arrays were used to identify the hypoxia-inducing factor-1 (HIF-1) as a downstream target of TGF-beta. HIF-1 is a basic helix-loop-helix protein, and overexpression of Id2 blocked HIF-1 activation by TGF-beta. Furthermore, knockdown of HIF-1 blocked TGF-beta-induced apoptosis. Thus, we have identified HIF-1 as a novel mediator downstream of Id2 in the pathway of TGF-beta-induced apoptosis.

Porphyromonas gingivalis with either Tannerella forsythia or Treponema denticola induces synergistic IL-6 production by murine macrophage-like J774.1 cells

BACKGROUND

Chronic periodontitis is caused by mixed bacterial infection. Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola are frequently detected in deep periodontal pockets. We demonstrate that these bacteria induce proinflammatory cytokine production by the mouse macrophage-like cell line J774.1.

MATERIALS AND METHODS

J774.1 cells were incubated with and without bacteria for 24h in 96-well flat-bottomed plates. The culture supernatants were analyzed by enzyme-linked immunosorbent assay for secreted mouse interleukin (IL)-6, monocyte chemoattractant protein-1, IL-23, IL-1 beta and tumor necrosis factor-alpha. The cytokine concentrations were determined using a standard curve prepared for each assay.

RESULTS

Mixed infection with P. gingivalis and either T. forsythia or T. denticola at 10(5)CFU/ml acted synergistically to increase IL-6 production, but not monocyte chemoattractant protein-1, IL-23, IL-1 beta or tumor necrosis factor-alpha production. Gingipain inhibitors KYT-1 and KYT-36 inhibited IL-6 production by J774.1 cells incubated with 10(5)CFU/ml of mixed bacteria.

CONCLUSION

These results suggest that P. gingivalis with either T. forsythia or T. denticola directly induces synergistic IL-6 protein production and that gingipains play a role in this synergistic effect.