Phosphorylcholine is located in Aggregatibacter actinomycetemcomitans fimbrial protein Flp 1.

Phosphorylcholine (ChoP) is covalently incorporated into bacterial surface structures, contributing to host mimicry and promoting adhesion to surfaces. Our aims were to determine the frequency of ChoP display among Aggregatibacter actinomycetemcomitans strains, to clarify which surface structures bear ChoP, and whether ChoP-positivity relates to serum killing. The tested oral (N = 67) and blood isolates (N = 27) represented 6 serotypes. Mab TEPC-15 was used for immunoblotting of cell lysates and fractions and for immunofluorescence microscopy of cell surface-bound ChoP. The lysates were denatured with urea for hidden ChoP or treated with proteinase K to test whether it binds to a protein. Three ChoP-positive and two ChoP-negative strains were subjected to serum killing in the presence/absence of CRP and using Ig-depleted serum as complement source. Cell lysates and the first soluble cellular fraction revealed a < 10 kDa band in immunoblots. Among 94 strains, 27 were ChoP positive. No difference was found in the prevalence of ChoP-positive oral (21/67) and blood (6/27) strains. Immunofluorescence microscopy corresponded to the immunoblot results. Proteinase K abolished ChoP reactivity, whereas urea did not change the negative result. The TEPC-15-reactive protein was undetectable in Δflp1 mutant strain. The survival rate of serotype-b strains in serum was 100% irrespective of ChoP, but that of serotype-a was higher in ChoP-positive (85%) than ChoP-negative (71%) strains. The results suggest that a third of rough-colony strains harbor ChoP and that ChoP is attached to fimbrial subunit protein Flp1. It further seems that ChoP-positivity does not enhance but may reduce A. actinomycetemcomitans susceptibility to serum killing.

Primary driving factors of ecological environment system change based on directed weighted network illustrating with the Three-River Headwaters Region.

The primary driving factors of ecological environment change have received significant attention. However, previous research methods for identifying the main drivers of ecological environment change have primarily relied on correlation analysis and regression analysis. While these methods can reveal co-occurrences, associations, and correlations among elemental characteristics, they often struggle to uncover the deep-seated interactions among elements within complex, unstable, nonlinear, and high-dimensional systems. To address this, we used the Three-River Headwaters Region as a case study and introduced a complex network model from the perspective of the ecological environment system to investigate the main driving factors of ecological environment change. In our analysis, we considered 12 factors related to the atmosphere, hydrology, vegetation, and soil, including evaporation, long-wave radiation, short-wave radiation, specific humidity, soil temperature, precipitation rate, soil water content, air temperature, air pressure, vegetation normalization index, wind speed, and natural surface runoff. Watersheds were selected as the fundamental units for constructing ecological environment datasets. We applied the Ensemble Empirical Mode Decomposition (EEMD) method and Hilbert-Huang Transform (HHT) to analyze causal relationships between time series pairs and constructed two directed weighted network models based on sub-catchments. The results showed that both network models yielded consistent conclusions, with the sparse network exhibiting higher efficiency. Radiation and temperature were identified as the primary driving factors of ecosystem change, and the water cycle was determined to be the ultimate manifestation of ecological system change throughout the Three-River Headwaters Region. Furthermore, based on node out-strength, we generated a vegetation protection priority map.

Hydrological impacts of vegetation cover change in China through terrestrial moisture recycling.

Terrestrial moisture recycling (TMR), characterized by a continuous process comprising green water flow (i.e., terrestrial evaporation), atmospheric transport, and terrestrial precipitation, functions as a nexus connecting hydrosphere, atmosphere, biosphere, and anthroposphere. During this process, land cover changes that impact green water flow can modify regional and remote precipitation patterns, potentially yielding far-reaching effects on water resources and human livelihoods. However, the comprehensive patterns of moisture recycling and transfer across eco-geographical regions in China, and their connection with various land cover types and vegetation transitions, remain insufficiently evaluated. This study employed an atmospheric moisture tracking model to quantify China's TMR pattern and evaluate the hydrological impacts of vegetation cover changes in China's ecosystems through TMR. The results demonstrate a significant moisture recycling ratio (52.4 %) and a considerable recycled volume (1.9 trillion m3/a) over China, characterized by pronounced moisture transfer from south to north and southwest to northeast. Among various land cover types, grasslands, croplands, and forests play pivotal supportive roles in China's TMR, contributing 738.8, 470.0, and 450.0 billion m3/a of precipitation in China, respectively. Moreover, the potential transition of vegetation between forest and cropland exerts the most significant and extensive impact on China's hydrological cycle. The conversion from forest to cropland leads to a total decrease of 44.7 billion m3/a in precipitation, whereas reforestation from cropland corresponds to a precipitation increase of 74.9 billion m3/a. This study provides a quantitative approach to comprehending the TMR pattern and its relationship with ecosystems, substantiating the significance of a comprehensive water management framework that considers the contribution of atmospheric moisture recycling and the impact of vegetation cover change.

Vesicle-independent extracellular release of a proinflammatory outer membrane lipoprotein in free-soluble form.

BACKGROUND: Aggregatibacter actinomycetemcomitans is an oral bacterium associated with aggressively progressing periodontitis. Extracellular release of bacterial outer membrane proteins has been suggested to mainly occur via outer membrane vesicles. This study investigated the presence and conservation of peptidoglycan-associated lipoprotein (AaPAL) among A. actinomycetemcomitans strains, the immunostimulatory effect of AaPAL, and whether live cells release this structural outer membrane lipoprotein in free-soluble form independent of vesicles. RESULTS: The pal locus and its gene product were confirmed in clinical A. actinomycetemcomitans strains by PCR-restriction fragment length polymorphism and immunoblotting. Culturing under different growth conditions revealed no apparent requirement for the AaPAL expression. Inactivation of pal in a wild-type strain (D7S) and in its spontaneous laboratory variant (D7SS) resulted in pleiotropic cellular effects. In a cell culture insert model (filter pore size 0.02 mum), AaPAL was detected from filtrates when strains D7S and D7SS were incubated in serum or broth in the inserts. Electron microscopy showed that A. actinomycetemcomitans vesicles (0.05-0.2 mum) were larger than the filter pores and that there were no vesicles in the filtrates. The filtrates were immunoblot negative for a cytoplasmic marker, cyclic AMP (cAMP) receptor protein. An ex vivo model indicated cytokine production from human whole blood stimulated by AaPAL. CONCLUSION: Free-soluble AaPAL can be extracellularly released in a process independent of vesicles.

[Role of platelet-activating factor receptor in adhesion and invasion of Aggregatibacter actinomycetemcomitans in human umbilical vein endothelial cells].

OBJECTIVE: To explore the role of platelet-activating factor receptor (PAFR) in adhesion and invasion of phospho- rylcholine (PC)-positive Aggregatibacter actinomycetemcomitans in cultured human umbilical vein endothelial cells (HUVEC). METHDOS: Cultured HUVECs were pretreated with the PAFR antagonist CV3988 or anti-human PAFR monoclonal antibody for 30 min before infection with PC-positive or -negative A. actinomycetemcomitans strains. The bacterial adhesion and invasion and cytotoxicity in the cells were examined using MTT assay. RESULTS: Pretreatment with PAFR antagonists at 100, 200 and 500 nmol/L significantly reduced the adhesion rate (36.29∓3.52)%, (19.04∓3.35)% and (7.69∓3.19%), respectively] and invasion rate [(12.12∓1.58)%, (7.08∓0.29)% and (2.60∓2.26)%, respectively] of PC-positive A.actinomycetemcomitans in HUVECs. Similarly, pretreatment with anti-PAFR antibody also significantly reduced A.actinomycetemcomitans adhesion and invasion in HUVECs [(50.05∓5.28)% and (39.09∓6.50)%, respectively]. Pretreatment with PAFR antagonist (200 and 500 nmol/L) and anti-PAFR antibody (25 µg/mL) significantly increased the viability of HUVECs incubated with PC-positive A.actinomycetemcomitans from (25.39∓9.33)% to (91.12∓3.14)%, (94.12∓2.15)% and (65.5∓1.87)%, respectively, but such pretreatments did not increase the viability of cells incubated with PC-negative A.actinomycetemcomitans. CONCLUSIONS: PAFR plays an important role in the adhesion, invasion, and cytotoxicity of PC-positive A.actinomycetemcomitans in cultured HUVECs.

Study on poly(vinyl alcohol)/carboxymethyl-chitosan blend film as local drug delivery system.

The distinguishable films composed of poly(vinyl alcohol) (PVA) and carboxymethyl-chitosan (CMCS) were prepared by blending/casting method, and loaded with ornidazole (OD) as local drug delivery system. In vitro test, the blend films showed pH-responsive swelling behavior and moderate drug release action, and also exhibited a little antimicrobial activity against E. coli and S. aureus strains. Those characteristics of CMCS/PVA blend films were essentially governed by the weight ratio of CMCS and PVA. Increasing the content of PVA in blend film would decrease swelling and decelerated the drug release. However, increasing the content of CMCS would enhance the antimicrobial activity. The biocompatibility and bioactivity of the blend film were also evaluated using rabbit blood and Wister rats. This blend drug system was of no hemolysis, no toxicity to rat periodontia and no cytotoxicity to the rat muscle. After subcutaneously implanting the blend drug films in Wister rat, the systems kept a good retention at the application site and maintained high drug concentration in long time (5 days) which was longer than the period of drug released in vitro (160 min).

[Relationship between periodontal disease and rheumatoid arthritis].

OBJECTIVE: To study a population of rheumatoid arthritis patients and determine the extent of periodontal disease in these patients, in order to investigate the relationship between periodontal disease and rheumatoid arthritis. METHODS: The experimental group was composed of 70 patients with rheumatoid arthritis and the control group consisted of 70 age- and gender-matched individuals without rheumatoid arthritis. The relationship between periodontal status in rheumatoid arthritis and control groups as well as the relationship between periodontal status and rheumatological findings in patients were analyzed. RESULTS: The percentage of periodontal disease was statistically significant between experimental and control group (P < 0.01). The difference of average number of missing teeth and bleeding on probing in the experimental group and control group were not statistically significant (P >0.05). There were more number of periodontal disease index 5 or 6 in experimental group than in control group ( P < 0.05). Rheumatoid arthritis patients with moderate to severe bone loss had deeper degree of morning stiffness, erythrocyte sedimentation rate levels and serum C-reactive protein levels than patients with no or mild bone loss. CONCLUSION: Individuals with rheumatoid arthritis are more likely to experience periodontal disease compares to healthy subjects. They are also very likely to suffer from moderate to severe periodontitis.