[Preliminary exploration of the clinical warning value of ischemic modified albumin in the development of pre-eclampsia].

Objective: To explore the clinical warning value of ischemic modified albumin (IMA) and IMA to human serum albumin (HSA) ratio (IMAR) in the development of pre-eclampsia (PE) and its severity. Methods: A total of 156 pregnant women with PE admitted to the Haidian District Maternal and Child Health Hospital of Beijing from April 2022 to March 2023 were collected as the PE group, and 156 healthy pregnant women with the same age and gestational age were matched as the control group. PE pregnant women were further divided into severe PE group (78 cases) and non-severe PE group (78 cases). Severe PE pregnant women were divided into emergency group (42 cases) and non-emergency group (36 cases) according to the disease progression time.All pregnant women were stratified according to their HSA levels (<30 g/L, 30-32 g/L, ≥32 g/L), and the peripheral blood IMA, HSA, and IMAR of pregnant women in different periods and subgroups were compared, and also the difference of IMA levels in umbilical artery blood. Bivariate correlation analysis was used to explore the correlation between severe PE and IMA or IMAR, and receiver operating characteristic (ROC) curves was used to analyze the diagnostic value of IMA, HSA, and IMAR for PE and severe PE. Results: (1) The IMA level and IMAR in peripheral serum of pregnant women in the PE group at diagnosis, and the IMA level in umbilical artery blood at delivery, and peripheral serum at 2 days after delivery were higher than those in the control group. The HSA level in peripheral serum was lower than that in the control group at diagnosis, and the differences were statistically significant (all P<0.001). (2) The IMA level and IMAR in the peripheral serum of pregnant women with severe PE were higher than those in the non-severe PE group at diagnosis, while the HSA level were lower than those in the non-severe PE group. The differences were statistically significant (all P<0.05). At diagnosis, the IMA level and IMAR in peripheral serum of pregnant women in the emergency group were higher than those in the non-emergency group, while the HSA level was lower than that in the non-emergency group. The differences were statistically significant (all P<0.05). When diagnosed, the peripheral serum IMA levels of pregnant women in the PE group were compared between subgroups with HSA<30 g/L, 30-32 g/L, ≥32 g/L, and there was no statistically significant difference (F=0.366, P=0.694). However, the IMAR was compared between the three subgroups, and the difference was statistically significant (F=28.544, P<0.001), which increased with the decrease of HSA levels. In the subgroup with HSA≥32 g/L, the peripheral serum IMA level and IMAR of pregnant women in the PE group were higher than those in the control group at diagnosis, and the differences were statistically significant (all P<0.001). (3) The severe PE manifestations positively correlated with peripheral serum IMAR at diagnosis include systolic blood pressure (r=0.279), mean arterial pressure (r=0.212), and urinary protein quantification (r=0.277), while the severe PE manifestations negatively correlated include HSA levels (r=-0.644) and newborn birth weight (r=-0.305), all of which were significantly correlated (P<0.05). (4) The area under curve (AUC) for IMAR diagnosis of PE was 0.875 (95%CI: 0.833-0.916), with the highest diagnostic efficiency at a cutoff value of 2.06, sensitivity of 72.5%, and specificity of 85.1%. The AUC for diagnosing severe PE was 0.871 (95%CI: 0.822-0.919), with the highest diagnostic efficacy at a cutoff value of 2.18, sensitivity of 72.3%, and specificity of 88.3%. The diagnostic efficacy of IMAR for PE and severe PE were higher than those of IMA and HSA levels. Conclusions: The level of IMA and IMAR in pregnant women with PE are higher than those in normal pregnant women. IMA and IMAR are correlated with the severity of PE, with IMAR changes occurring earlier and more significantly. IMAR could be considered as one of the evaluation indicators for the development of PE, or as a more sensitive PE severity warning indicator than HSA.

[Diagnostic value of rapid exchange test in patients with peritoneal dialysis catheter dysfunction].

A total of 36 patients with suspected peritoneal dialysis (PD) catheter dysfunction in the First Hospital of China Medical University from June 2020 to August 2022 were included, and five patients with normal PD catheter were also included as the control group. There were 22 males and 19 females, and aged (45±21) years. The volume of rapid-phase drainage in the control and dysfunction groups was (2 086±65) and (1 181±637) ml, and the total drainage time was (15.2±1.3) and (38.3±14.9) min, respectively. The volume of rapid-phase drainage in the dysfunction group was reduced and the total drainage time was longer than that in the control group (both P<0.05). Compared with group with PD catheter migration, the duration of new bag instillation was prolonged, the drainage volume in the rapid-phase was reduced, the total drainage duration was prolonged, and the ultrafiltration volume was decreased in the group with PD catheter obstruction (all P<0.05). The rapid exchange test can provide an early preliminary diagnosis of PD catheter dysfunction and identify the type of catheter dysfunction.

[Clinical analysis of 16 children with traumatic basal ganglia stroke].

Objective: To investigate the clinical characteristics and risk-factors of traumatic basal ganglia stroke (TBGS) in children. Methods: A retrospective case study was conducted to analyze the clinical and imaging data of 16 children with TBGS in the First Hospital of Jilin University from January 2014 to June 2017. A total of 16 TBGS cases (11 males, 5 females) were diagnosed and the age ranged from 0.5 to 13.0 years. The prognosis of children with TBGS at different ages (≥5 years and<5 years) and with different traumatic stroke (infarction and hemorrhage) were compared. Fisher 's test was used to compare the prognosis of different groups. Results: All cases had clear history of head trauma and varying degrees of limb paralysis after injury, including 4 cases of facial paralysis, 3 cases of consciousness disturbance and 1 case of seizures. Head CT scan of the 16 cases showed 11 cases of ischemic stroke and 5 cases of hemorrhagic stroke. Moreover, scattered calcification was observed in the bilateral basal ganglia point of 8 cases. Neurotrophic treatment, microcirculation improvement and nerve rehabilitations were given according to the clinical and imaging data. One patient was treated with craniotomy and hematoma clearance. Of the 16 cases, 11 cases were restored to normal, while 3 cases developed limb paralysis and 2 cases died. The prognosis of 11 cases of traumatic basal ganglia infarction (10 cases recovered and 1 case remained hemiplegic) was relatively better than that of 5 cases of hemorrhage (1 case recovered, 2 cases remained hemiplegic and 2 cases died) (χ(2)=8.045, P=0.013). In addition, the children younger than 5-year-old (all 8 cases recovered) had a better prognosis than the children older than 5-year-old (8 cases, 3 of whom recovered, 3 cases remained hemiplegia, 2 cases died)(χ(2)=12.121, P<0.01). Conclusions: The anatomical characteristics of basal ganglia and calcification of the lenticulostriate artery are risk-factors for TBGS in children. The prognosis of infarcted children and younger children is relatively better.

Adaption, translation and validation of the Diabetes Mellitus in the Offspring Questionnaire (DMOQ): The Malay version.

BACKGROUND: The Diabetes Mellitus in the Offspring Questionnaire (DMOQ) assesses the perceptions of Type 2 diabetes mellitus (T2DM) patients on the risk of their offspring developing T2DM and the possibility of intervention to reduce this risk. It has 34 items framed within seven domains. This study aimed to adapt, translate and validate the DMOQ from English into the Malay language. METHODS: This was a cross-sectional validation study among 159 T2DM patients attending a public primary care clinic in Selangor. The DMOQ English version underwent adaptation, translation, face validation and field testing to produce the Malay version. Psychometric analysis was performed using Exploratory Factor Analysis, internal consistency and testretest reliability. RESULTS: The DMOQ domains were conceptually equivalent between English and Malay language. A total of 13 items and two domains were removed during the validation process (three items during the content validation, three items due to poor factor loadings, five items as they loaded onto two domains which were not interpretable, one item as it did not fit conceptually into the factor it loaded onto and one openended question as it did not fit into the retained domains). Therefore, the final DMOQ Malay version consisted of 21- items within five domains. The Cronbach alpha was 0.714 and the intraclass-correlation coefficient was 0.868. CONCLUSION: The DMOQ Malay version is a valid and reliable tool which is consistent over time. It can be used to examine the perception of T2DM patients towards the risk of their offspring developing diabetes and possibility of intervention in Malay-speaking patients.

[Variation of long-chain 3-hydroxyacyl CoA dehydrogenase DNA methylated modification and correlation with gene mRNA expression of early-onset preeclampsia, HELLP syndrome and antiphospholipid syndrome in trophoblast cells of placenta].

OBJECTIVE: By detecting the DNA methylation and gene expression of long-chain 3-hydroxyacyl CoA dehydrogenase(LCHAD)in trophoblast cells, analyze the correlation of DNA methylation and gene expression in early-onset preeclampsia(EPE), hemolysis, elevated liver enzymes, and low platelets(HELLP)syndrome and antiphospholipid syndrome(APS), to investigate the molecular basis of long-chain fatty acid oxidation changes in different preeclampsia and pathological pregnancy. METHODS: Primary human cytotrophoblast cells and HTR8/Svneo cells were treated with serum from patients with EPE(14 cases), HELLP(12 cases), APS(14 cases), and normal pregnant women(NP, 14 cases). The methylation level of LCHAD gene promoter region through the MassARRAY platform and mRNA expression level by real-time fluorescent quantitative PCR technique were conducted. RESULTS: (1)Cytosine-phosphate-guanine(CpG)sites in human LCHAD DNA promoter region: CpG sites were detected in the range of 558 bp before LCHAD gene transcription start site, the detected CpG sites were 11 sites including 8 single sites and 3 complex sites. The position of these sites were at-984,-960,-899,-853,-811,-796,-774,-727,-615,-595,-579 respectively.(2)The sites of-899,-853,-615 and-595 showed increased methylation level in EPE and HELLP groups. The methylation level at-899,-853 and-615 sites in EPE and HELLP groups were significantly higher than those in NP group(P<0.01). The methylation level at-853 site was higher in EPE group than that in HELLP group(P<0.05). The-595 site showed the unmethylated in EPE, HELLP and APS groups. There were significantly difference between the 3 groups and EPE group(P<0.01).(3)The gene expression of LCHAD mRNA in EPE(0.048±0.005), HELLP(0.045±0.006)and APS(0.044±0.004)groups were significantly lower than NP group(0.076±0.009; P<0.01).(4)The correlation of methylation level and gene expression in all groups: the methylation level at-899,-853,-727,-615 and-579 sites were negatively correlated with gene mRNA expression in EPE group(P<0.05). The methylation level at-899,-853 and-615 sites were negatively correlated with gene mRNA expression in HELLP group(P< 0.05). CONCLUSIONS: The variation of LCHAD DNA methylation of trophoblast cells are found among EPE, HELLP syndrome and APS. The different correlation of LCHAD DNA methylation and gene expression are different in pathological groups. LCHAD DNA methylation of EPE and HELLP syndrome were significantly increased and negatively correlated with LCHAD gene mRNA expression. These results further revealed the molecular basis of long-chain fatty acid oxidation in different preeclampsia and pathological pregnancy.

Fap2 of Fusobacterium nucleatum is a galactose-inhibitable adhesin involved in coaggregation, cell adhesion, and preterm birth.

Fusobacterium nucleatum is a common oral anaerobe involved in periodontitis that is known to translocate and cause intrauterine infections. In the oral environment, F. nucleatum adheres to a large diversity of species, facilitating their colonization and creating biological bridges that stabilize the multispecies dental biofilm. Many of these interactions (called coadherences or coaggregations) are galactose sensitive. Galactose-sensitive interactions are also involved in the binding of F. nucleatum to host cells. Hemagglutination of some F. nucleatum strains is also galactose sensitive, suggesting that a single galactose-sensitive adhesin might mediate the interaction of fusobacteria with many partners and targets. In order to identify the fusobacterial galactose-sensitive adhesin, a system for transposon mutagenesis in fusobacteria was created. The mutant library was screened for hemagglutination deficiency, and three clones were isolated. All three clones were found to harbor the transposon in the gene coding for the Fap2 outer membrane autotransporter. The three fap2 mutants failed to show galactose-inhibitable coaggregation with Porphyromonas gingivalis and were defective in cell binding. A fap2 mutant also showed a 2-log reduction in murine placental colonization compared to that of the wild type. Our results suggest that Fap2 is a galactose-sensitive hemagglutinin and adhesin that is likely to play a role in the virulence of fusobacteria.

Periodontal disease, atherosclerosis, adverse pregnancy outcomes, and head-and-neck cancer.

Interrelationships between periodontal infection and systemic conditions such as cardiovascular disease, adverse pregnancy outcomes, and head-and-neck cancer have become increasingly appreciated in recent years. Periodontitis is associated with cardiovascular disease (CVD) and, experimentally, with measures of atherosclerosis and endothelial dysfunction. Periodontal therapy may reduce atherosclerotic changes and improve endothelial function. Preliminary findings suggest a role for the genetic locus ANRIL in the pathobiology of both CVD and periodontitis. Periodontal pathogens induce anticardiolipin in periodontitis patients by molecular mimicry of the serum protein ß-2 glycoprotein I. These antibodies have biological and pathological activities consistent with those reported for other infection-induced antiphospholipid antibodies. Anticardiolipin may explain some of the observed associations between periodontitis and systemic conditions such as CVD and adverse pregnancy outcomes. The oral commensal Fusobacterium nucleatum (Fn) becomes pathogenic on migration to extra-oral sites. Fn infection of the fetal-placental unit has been linked to pregnancy complications, including preterm birth, stillbirth, and early-onset neonatal sepsis. Reagents aimed at inhibiting or resolving inflammatory responses may be used to treat or prevent pregnancy complications due to bacterial infection. Chronic periodontitis may be independently associated with head-and-neck squamous cell carcinoma (HNSCC) through direct toxic effects of bacteria and their products, and/or through indirect effects of inflammation. Additionally, chronic periodontitis may facilitate the acquisition and persistence of oral HPV infection, a recently emerged risk factor for HNSCC.

Mobile microbiome: oral bacteria in extra-oral infections and inflammation.

The link between oral infections and adverse systemic conditions has attracted much attention in the research community. Several mechanisms have been proposed, including spread of the oral infection due to transient bacteremia resulting in bacterial colonization in extra-oral sites, systemic injury by free toxins of oral pathogens, and systemic inflammation caused by soluble antigens of oral pathogens. Mounting evidence supports a major role of the systemic spread of oral commensals and pathogens to distant body sites causing extra-oral infections and inflammation. We review here the most recent findings on systemic infections and inflammation complicated by oral bacteria, including cardiovascular disease, adverse pregnancy outcomes, rheumatoid arthritis, inflammatory bowel disease and colorectal cancer, respiratory tract infections, and organ inflammations and abscesses. The recently identified virulence mechanisms of oral species Fusobacterium nucleatum, Porphyromonas gingivalis, Streptococcus mutans, and Campylobacter rectus are also reviewed. A pattern emerges indicating that only select subtype(s) of a given species, e.g., F. nucleatum subspecies animalis and polymorphum and S. mutans non-c serotypes, are prone to extra-oral translocation. These findings advocate the importance of identification and quantification of potential pathogens at the subtype levels for accurate prediction of disease potential.

IFPA Meeting 2010 Workshop Report I: Immunology; ion transport; epigenetics; vascular reactivity; epitheliochorial placentation; proteomics.

Workshops are an important part of the IFPA annual meeting. At IFPA Meeting 2010 there were twelve themed workshops, six of which are summarized in this report. 1. The immunology workshop focused on normal and pathological functions of the maternal immune system in pregnancy. 2. The transport workshop dealt with regulation of ion and water transport across the syncytiotrophoblast of human placenta. 3. The epigenetics workshop covered DNA methylation and its potential role in regulating gene expression in placental development and disease. 4. The vascular reactivity workshop concentrated on methodological approaches used to study placental vascular function. 5. The workshop on epitheliochorial placentation covered current advances from in vivo and in vitro studies of different domestic species. 6. The proteomics workshop focused on a variety of techniques and procedures necessary for proteomic analysis and how they may be implemented for placental research.

Oral health and adverse pregnancy outcomes - what's next?

Studies on the link between periodontal disease and adverse pregnancy outcome have gone through several phases. The epidemiological studies predominantly support a positive association between these wide-affecting diseases. During the intervention phase, a few small-scale, single-center studies reported improvement of birth outcome following periodontal treatment, whereas the large-scale multi-center studies did not demonstrate efficacy. Many questions arise with regard to patient population, disease type, and therapy. In addressing these questions, it is crucial that one understands the mechanism underlying the link between these diseases. Two non-mutually exclusive hypotheses exist. In the first, periodontal disease is believed to affect the maternal and fetal immune responses systemically, leading to premature labor. Alternatively, evidence is accumulating that oral bacteria may translocate directly into the pregnant uterus, causing localized inflammation and adverse pregnancy outcome in the presence or absence of clinical periodontitis. The oral-uterine transmission is not limited to the well-recognized periodontal pathogens, but instead may also involve the commensal species. Future studies should investigate these mechanisms, to understand the host susceptibility to oral-uterine transmission. Only when a thorough understanding of the mechanism is achieved can meaningful intervention studies be designed utilizing effective therapies, targeting appropriate populations, and measuring relevant outcomes.

Periodontal therapy reduces the severity of active rheumatoid arthritis in patients treated with or without tumor necrosis factor inhibitors.

BACKGROUND: Rheumatoid arthritis (RA) and periodontitis are common chronic inflammatory conditions. Recent studies showed a beneficial effect of periodontal treatment on the severity of active RA. This study was undertaken to further examine the effect of non-surgical periodontal treatment on the signs and symptoms of RA in patients treated with or without anti-tumor necrosis factor-alpha (anti-TNF-alpha) medications. The effect of anti-TNF-alpha therapy on periodontitis also was assessed. METHODS: Forty participants diagnosed with moderate/severe RA (under treatment for RA) and severe periodontitis were randomly assigned to receive initial non-surgical periodontal therapy with scaling/root planing and oral hygiene instructions (n = 20) or no periodontal therapy (n = 20). To control RA, all participants had been using disease-modifying anti-rheumatic drugs, and 20 had also been using anti-TNF-alpha before randomization. Probing depth (PD), clinical attachment level (CAL), bleeding on probing (BOP), gingival index (GI), plaque index (PI), RA disease activity score 28 (DAS28), and erythrocyte sedimentation rate (ESR) were measured at baseline and 6 weeks later. Linear mixed models were used to identify significant differences between subjects who received periodontal treatment and those who did not. RESULTS: Patients receiving periodontal treatment showed a significant decrease in the mean DAS28, ESR (P <0.001), and serum TNF-alpha (P <0.05). There was no statistically significant decrease in these parameters in patients not receiving periodontal treatment. Anti-TNF-alpha therapy resulted in a significant improvement in CAL, PD, BOP, and GI. CONCLUSIONS: Non-surgical periodontal therapy had a beneficial effect on the signs and symptoms of RA, regardless of the medications used to treat this condition. Anti-TNF-alpha therapy without periodontal treatment had no significant effect on the periodontal condition.

Spatiotemporal effects of sonoporation measured by real-time calcium imaging.

To investigate the effects of sonoporation, spatiotemporal evolution of ultrasound-induced changes in intracellular calcium ion concentration ([Ca(2+)](i)) was determined using real-time fura-2AM fluorescence imaging. Monolayers of Chinese hamster ovary (CHO) cells were exposed to a 1-MHz ultrasound tone burst (0.2 s, 0.45 MPa) in the presence of Optison microbubbles. At extracellular [Ca(2+)](o) of 0.9 mM, ultrasound application generated both nonoscillating and oscillating (periods 12 to 30 s) transients (changes of [Ca(2+)](i) in time) with durations of 100-180 s. Immediate [Ca(2+)](i) transients after ultrasound application were induced by ultrasound-mediated microbubble-cell interactions. In some cases, the immediately affected cells did not return to pre-ultrasound equilibrium [Ca(2+)](i) levels, thereby indicating irreversible membrane damage. Spatial evolution of [Ca(2+)](i) in different cells formed a calcium wave that was observed to propagate outward from the immediately affected cells at 7-20 microm/s over a distance >200 microm, causing delayed transients in cells to occur sometimes 60 s or more after ultrasound application. In calcium-free solution, ultrasound-affected cells did not recover, consistent with the requirement of extracellular Ca(2+) for cell membrane recovery subsequent to sonoporation. In summary, ultrasound application in the presence of Optison microbubbles can generate transient [Ca(2+)](i) changes and oscillations at a focal site and in surrounding cells via calcium waves that last longer than the ultrasound duration and spread beyond the focal site. These results demonstrate the complexity of downstream effects of sonoporation beyond the initial pore formation and subsequent diffusion-related transport through the cellular membrane.

A unique beta-hairpin protruding from AAA+ ATPase domain of RuvB motor protein is involved in the interaction with RuvA DNA recognition protein for branch migration of Holliday junctions.

The Escherichia coli RuvB protein is a motor protein that forms a complex with RuvA and promotes branch migration of Holliday junctions during homologous recombination. This study describes the characteristics of two RuvB mutants, I148T and I150T, that do not promote branch migration in the presence of RuvA. These RuvB mutants hydrolyzed ATP and bound duplex DNA with the same efficiency as wild-type RuvB, but the mutants did not form a complex with RuvA and were defective in loading onto junction DNA in a RuvA-assisted manner. A recent crystallographic study revealed that Ile(148) and Ile(150) are in a unique beta-hairpin that protrudes from the AAA(+) ATPase domain of RuvB. We propose that this beta-hairpin interacts with hydrophobic residues in the mobile third domain of RuvA and that this interaction is vital for the RuvA-assisted loading of RuvB onto Holliday junction DNA.

Mutational analysis of the functional motifs of RuvB, an AAA+ class helicase and motor protein for holliday junction branch migration.

Escherichia coli RuvB protein, together with RuvA, promotes branch migration of Holliday junctions during homologous recombination and recombination repair. The RuvB molecular motor is an intrinsic ATP-dependent DNA helicase with a hexameric ring structure and its architecture has been suggested to be related to those of the members of the AAA+ protein class. In this study, we isolated a large number of plasmids carrying ruvB mutant genes and identified amino acid residues important for the RuvB functions by examining the in vivo DNA repair activities of the mutant proteins. Based on these mutational studies and amino acid conservation among various RuvBs, we identified 10 RuvB motifs that agreed well with the features of the AAA+ protein class and that distinguished the primary structure of RuvB from that of typical DNA/RNA helicases with seven conserved helicase motifs.

Interactions between periodontal bacteria and human oral epithelial cells: Fusobacterium nucleatum adheres to and invades epithelial cells.

Bacteria are causative agents of periodontal diseases. Interactions between oral bacteria and gingival epithelial cells are essential aspects of periodontal infections. Using an in vitro tissue culture model, a selected group of gram-negative anaerobic bacteria frequently associated with periodontal diseases, including Bacteroides forsythus, Campylobacter curvus, Eikenella corrodens, Fusobacterium nucleatum, Porphyromonas gingivalis, and Prevotella intermedia, were examined for their ability to adhere to and invade primary cultures of human gingival epithelial cells (HGEC). The effects of these bacteria on the production of interleukin-8 (IL-8), a proinflammatory chemokine, were also measured. These studies provided an initial demonstration that F. nucleatum adhered to and invaded HGEC and that this was accompanied by high levels of IL-8 secretion from the epithelial cells. The attachment and invasion characteristics of F. nucleatum were also tested using KB cells, an oral epithelial cell line. The invasion was verified by transmission electron microscopy and with metabolic inhibitors. Invasion appeared to occur via a "zipping" mechanism and required the involvement of actins, microtubules, signal transduction, protein synthesis, and energy metabolism of the epithelial cell, as well as protein synthesis by F. nucleatum. A spontaneous mutant, lam, of F. nucleatum, isolated as defective in autoagglutination, was unable to attach to or invade HGEC or KB cells, further indicating the requirement of bacterial components in these processes. Sugar inhibition assays indicated that lectin-like interactions were involved in the attachment of F. nucleatum to KB cells. Investigation of these new virulence phenotypes should improve our understanding of the role of F. nucleatum in periodontal infections.

Induction of apoptotic cell death in peripheral blood mononuclear and polymorphonuclear cells by an oral bacterium, Fusobacterium nucleatum.

It is largely unknown why a variety of bacteria present in the oral cavity are capable of establishing themselves in the periodontal pockets of nonimmunocompromised individuals in the presence of competent immune effector cells. In this paper we present evidence for the immunosuppressive role of Fusobacterium nucleatum, a gram-negative oral bacterium which plays an important role in the generation of periodontal disease. Our studies indicate that the immunosuppressive role of F. nucleatum is largely due to the ability of this organism to induce apoptotic cell death in peripheral blood mononuclear cells (PBMCs) and in polymorphonuclear cells (PMNs). F. nucleatum treatment induced apoptosis of PBMCs and PMNs as assessed by an increase in subdiploid DNA content determined by DNA fragmentation and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end-labeling assays. The ability of F. nucleatum to induce apoptosis was abolished by either heat treatment or proteinase digestion but was retained after formaldehyde treatment, suggesting that a heat-labile surface protein component is responsible for bacterium-mediated cell apoptosis. The data also indicated that F. nucleatum-induced cell apoptosis requires activation of caspases and is protected by NF-kappaB. Possible mechanisms of F. nucleatum's role in the pathogenesis of periodontal disease are discussed.

Identification and characterization of human immunoglobulin G Fc receptors of Fusobacterium nucleatum.

Several human pathogens express components which can bind to the Fc portion of immunoglobulins. This study was undertaken to characterize the human immunoglobulin G (IgG) Fc-binding activity of Fusobacterium nucleatum, a suspected pathogen involved in periodontal diseases. Fc-binding activity was detected using whole-cell, cell envelope and outer membrane fractions, and it was found to be associated with polypeptides of 40 kDa and 42 kDa, respectively. Amino terminal sequencing of these components revealed them to be homologous to the bacterial porin encoded by fomA gene. Further sequencing of internal peptide fragments obtained by CNBr cleavage suggested that these two proteins are probably isoforms. In summary, we show that a porin-like protein on the surface of F. nucleatum can bind the Fc fragment of the human immunoglobulin G, and this protein may act as a virulence factor to facilitate this bacterium in evading host immune surveillance system.

Expression of bvgAS of Bordetella pertussis represses flagellar biosynthesis of Escherichia coli.

BvgAS is a two-component system of Bordetella pertussis involved in the reciprocal regulation of the virulence genes and the flagellar biosynthesis. In this study, we found that expression of bvgAS in Escherichia coli also results in reduced motility. The repression was relieved by the addition of known chemical modulators of BvgAS such as MgSO4 and nicotinic acid, indicating that functional BvgAS proteins are required for the negative control of E. coli motility. In addition, BvgAS repressed the transcription of the flhDC master operon of E. coli, which consequently caused non-flagellation on the cell surface. However, expression of BvgAS had no effect on stress-resistant motile mutants of E. coli. These data suggest that E. coli may have BvgA-like protein(s) involved in the regulatory interactions between the stress response and the flagellar biosynthesis.

Reevaluation of the virulence phenotype of the inv yadA double mutants of Yersinia pseudotuberculosis.

Yersinia pseudotuberculosis and Yersinia enterocolitica are closely related human pathogens causing gastroenteritis. Invasin and YadA are two of the most extensively studied virulence factors of the Yersinia genus. Invasin is the primary invasion factor encoded by the inv gene on the chromosome and is required for the penetration of the epithelial cells. YadA is encoded by the yadA gene on the 70-kb virulence plasmid and has multiple functions. Previous studies indicate that an inv yadA double mutant of Y. enterocolitica is avirulent while an inv yadA mutant of Y. pseudotuberculosis is hypervirulent. In this study, we investigated this unexpected difference. New constructs of the inv yadA mutants of Y. pseudotuberculosis were made and tested in mice. These new constructs were not hypervirulent; rather, they maintained the same virulence as the wild-type strain. Further examination of the inv mutant used for the previous study revealed that it carries an aberrant inv phenotype and has an altered outer membrane profile and an altered colony morphology. Therefore, the mutants used previously were not isogenic to the parental wild-type strain, which may in part account for the difference in the results obtained.