Background
Previous work has demonstrated that anastomotic leak can be caused by collagenolytic bacteria such as Enterococcus faecalis via an effect on wound collagen. In humans, E. faecalis is the ...organism cultured most commonly from a leaking anastomosis, and is not routinely eliminated by standard oral or intravenous antibiotics. Novel strategies are needed to contain the virulence of this pathogen when present on anastomotic tissues.
Methods
Polyphosphorylated polymer ABA‐PEG20k‐Pi20 was tested in mice for its ability to prevent anastomotic leak caused by collagenolytic E. faecalis. The study design included a distal colonic resection and anastomosis followed by introduction of E. faecalis to anastomotic tissues via enema. Mice were assigned randomly to receive either ABA‐PEG20‐Pi20 or its unphosphorylated precursor ABA‐PEG20k in their drinking water. The development of anastomotic leak was determined after the animals had been killed.
Results
Overnight incubation of two different E. faecalis collagenolytic strains with 2 mmol/l of ABA‐PEG20k‐Pi20 led to near complete inhibition of collagenase production (from 21 000 to 1000 and from 68 000 to 5000 units; P < 0·001; 6 samples per group) without suppressing bacterial growth. In mice drinking 1 per cent ABA‐PEG20k‐Pi20, the phosphate concentration in the distal colonic mucosa increased twofold and leak rates decreased from eight of 15 to three of 15 animals (P < 0·001). In mice drinking ABA‐PEG20k‐Pi20, the percentage of collagenolytic colonies among E. faecalis populations present at anastomotic tissue sites was decreased by 6–4800‐fold (P = 0·008; 5 animals).
Conclusion
These data indicate that oral intake of ABA‐PEG20k‐Pi20 may be an effective agent to contain the virulence of E. faecalis and may prevent anastomotic leak caused by this organism.
Clinical relevance
Progress in understanding the pathogenesis of anastomotic leak continues to point to intestinal bacteria as key causative agents. The presence of pathogens such as Enterococcus faecalis that predominate on anastomotic tissues despite antibiotic use, coupled with their ability to produce collagenase, appears to alter the process of healing that leads to leakage. Further antibiotic administration may seem logical, but carries the unwanted risk of eliminating the normal microbiome, which functions competitively to exclude and suppress the virulence of pathogens such as E. faecalis. Therefore, non‐antibiotic strategies that can suppress the production of collagenase by E. faecalis without affecting its growth, or potentially normal beneficial microbiota, may have unique advantages. The findings of this study demonstrate that drinking a phosphate‐based polymer can achieve the goal of preventing anastomotic leak by suppressing collagenase production in E. faecalis without affecting its growth.
Further evidence the microbiome may be important
Mainstay treatment for Plasmodium vivax malaria has long relied on chloroquine (CQ) against blood-stage parasites plus primaquine against dormant liver-stage forms (hypnozoites), however drug ...resistance confronts this regimen and threatens malaria control programs. Understanding the basis of P. vivax chloroquine resistance (CQR) will inform drug discovery and malaria control. Here we investigate the genetics of P. vivax CQR by a cross of parasites differing in drug response. Gametocytogenesis, mosquito infection, and progeny production are performed with mixed parasite populations in nonhuman primates, as methods for P. vivax cloning and in vitro cultivation remain unavailable. Linkage mapping of progeny surviving >15 mg/kg CQ identifies a 76 kb region in chromosome 1 including pvcrt, an ortholog of the Plasmodium falciparum CQR transporter gene. Transcriptional analysis supports upregulated pvcrt expression as a mechanism of CQR.
Calpain is distributed ubiquitously in virtually every tissue (Croall, D. E., and DeMartino, G. N. (1991) Physiol. Rev. 71,
813-846), but its physiological role remains to be determined. The ...identification of its natural endogenous substrates would
be of great interest. Since pp60src, a major tyrosine kinase in platelets, is known to be easily cleaved during purification
from cells (Feder, D., and Bishop, J. M. (1990) J. Biol. Chem. 265, 8205-8211), we examined the possibility that it is an
endogenous substrate of calpain. In the whole cell lysate from resting platelets, which was analyzed by Western blotting with
monoclonal antibody 327, we found pp60src almost exclusively in a 60-kDa form, with a trace of 52-kDa form. Addition of A23187
(a calcium ionophore) or dibucaine, which are known to be activators of platelet calpain (Croall and DeMartino, 1991; Fox,
J. E., Reynolds, C., Morrow, J. S., and Phillips, D. R. (1987) Blood 76, 2510-2519; Fox, J. E., Austin, C. D., Boyles, J.
K., and Steffen, P. K. (1990b) J. Cell Biol. 111, 483-493), caused dose- and time-dependent cleavage of actin-binding protein
and p235 protein (talin). At the same time, loss of the 60-kDa species of pp60src and generation of the 52-kDa (occasionally
seen as doublets) and 47-kDa species were detected by the Western blotting. In platelets aggregated by 1 unit/ml thrombin,
apparently identical cleavage products were found. The cleavage of pp60src was inhibited by calpeptin (20 microM), an inhibitor
of calpain (Tsujinaka, T., Kajiwara, Y., Kambayashi, J., Sakon, M., Higuchi, N., Tanaka, T., and Mori, T. (1988) Biochem.
Biophys. Res. Commun. 153, 1201-1208; Tsujinaka, T., Ariyoshi, H., Uemura, Y., Sakon, M., Kambayashi, J., and Mori, T. (1990)
Life Sci. 46, 1059-1066; Fox, J. E., Clifford, C. C., and Austin, C. D. (1990) Blood 76, 2510-2519; Fox, J. E., Austin, C.
D., Boyles, J. K., and Steffen, P. K. (1990) J. Cell. Biol. 111, 483-493; Fox, J. E., Austin, C. D., Clifford, C. C., and
Steffen, P. K. (1991) J. Biol. Chem. 266, 13289-13295). Addition of EGTA (3 mM) to the extracellular media completely inhibited
the cleavage of actin-binding protein, talin, and pp60src in response to A23187 (1 microM). Intact pp60src was distributed
in both cytosolic and particulate (membrane) fractions. Cleaved species were found exclusively in the cytosolic fraction.
pp60src-associated enolase kinase activity was reduced. Thus, pp60src is an endogenous substrate for calpain, the cleavage
of which may have regulatory effects on the kinase.
By age 5, approximately one-fifth of children have early childhood caries (ECC). Both the oral microbiome and host genetics are thought to influence susceptibility. Whether the oral microbiome ...modifies genetic susceptibility to ECC has not been tested. We test whether the salivary bacteriome modifies the association of a polygenic score (PGS, a score derived from genomic data that summarizes genetic susceptibility to disease) for primary tooth decay on ECC in the Center for Oral Health Research in Appalachia 2 longitudinal birth cohort. Children were genotyped using the Illumina Multi-Ethnic Genotyping Array and underwent annual dental examinations. We constructed a PGS for primary tooth decay using weights from an independent, genome-wide association meta-analysis. Using Poisson regression, we tested for associations between the PGS (high versus low) and ECC incidence, adjusting for demographic characteristics (n = 783). An incidence-density sampled subset of the cohort (n = 138) had salivary bacteriome data at 24 mo of age. We tested for effect modification of the PGS on ECC case status by salivary bacterial community state type (CST). By 60 mo, 20.69% of children had ECC. High PGS was not associated with an increased rate of ECC (incidence rate ratio, 1.09; 95% confidence interval CI, 0.83–1.42). However, having a cariogenic salivary bacterial CST at 24 mo was associated with ECC (odds ratio OR, 7.48; 95% CI, 3.06–18.26), which was robust to PGS adjustment. An interaction existed between the salivary bacterial CST and the PGS on the multiplicative scale (P = 0.04). The PGS was associated with ECC (OR, 4.83; 95% CI, 1.29–18.17) only among individuals with a noncariogenic salivary bacterial CST (n = 70). Genetic causes of caries may be harder to detect when not accounting for cariogenic oral microbiomes. As certain salivary bacterial CSTs increased ECC risk across genetic risk strata, preventing colonization of cariogenic microbiomes would be universally beneficial.
Shape memory polymers (SMPs) respond to heat by generating programmable movement in devices that require substantial deformation and operate at transient temperatures, including stents and ...embolization coils. To enable their use in small‐scale applications like retinal vasculature stenting, shape transformations must occur in SMPs with complex 3D geometries with nanoscale features. This work describes the synthesis and sculpting of a benzyl methacrylate‐based SMP into 3D structures with <800 nm characteristic critical dimensions via two photon lithography. Dynamic nanomechanical analysis of 8 µm‐diameter cylindrical pillars reveal the initiation of this SMP's glass transition at 60 °C. Shape memory programming of the characterized pillars as well as complex 3D architectures, including flowers with 500 nm thick petals and cubic lattices with 2.5 µm unit cells and overall dimensions of 4.5 µm × 4.5 µm × 10 µm, demonstrate an 86 +/− 4% characteristic shape recovery ratio. These results reveal a pathway toward SMP devices with nanoscale features and arbitrary 3D geometries changing shape in response to temperature.
Shape memory microscale 3D polymer architectures are achieved through two photon direct laser writing of a benzyl methacrylate based crosslinked elastomeric network. Dynamic nanomechanical analysis experiments and in situ shape memory programming of structures with sub‐micron features indicate glass transition triggered shape changes, enabling future design of stand‐alone microscale deployable structures and stimuli responsive architected materials.
Objective:
Describe associations between dental caries and dental plaque microbiome, by dentition and family membership.
Methods:
This cross-sectional analysis included 584 participants in the Center ...for Oral Health Research in Appalachia Cohort 1 (COHRA1). We sequenced the 16S ribosomal RNA gene (V4 region) of frozen supragingival plaque, collected 10 y prior, from 185 caries-active (enamel and dentinal) and 565 caries-free (no lesions) teeth using the Illumina MiSeq platform. Sequences were filtered using the R DADA2 package and assigned taxonomy using the Human Oral Microbiome Database.
Results:
Microbiomes of caries-active and caries-free teeth were most similar in primary dentition and least similar in permanent dentition, but caries-active teeth were significantly less diverse than caries-free teeth in all dentition types. Streptococcus mutans had greater relative abundance in caries-active than caries-free teeth in all dentition types (P < 0.01), as did Veillonella dispar in primary and mixed dentition (P < 0.01). Fusobacterium sp. HMT 203 had significantly higher relative abundance in caries-free than caries-active teeth in all dentition types (P < 0.01). In a linear mixed model adjusted for confounders, the relative abundance of S. mutans was significantly greater in plaque from caries-active than caries-free teeth (P < 0.001), and the relative abundance of Fusobacterium sp. HMT 203 was significantly lower in plaque from caries-active than caries-free teeth (P < 0.001). Adding an effect for family improved model fit for Fusobacterium sp. HMT 203 but notS. mutans.
Conclusions:
The diversity of supragingival plaque composition from caries-active and caries-free teeth changed with dentition, but S. mutans was positively and Fusobacterium sp. HMT 203 was negatively associated with caries regardless of dentition. There was a strong effect of family on the associations of Fusobacterium sp. HMT 203 with the caries-free state, but this was not true for S. mutans and the caries-active state.
Knowledge Transfer Statement:
Patients’ and dentists’ concerns about transmission of bacteria within families causing caries should be tempered by the evidence that some shared bacteria may contribute to good oral health.
Concerns about malaria parasite resistance to treatment with artemisinin drugs (ARTs) have grown with findings of prolonged parasite clearance t
1/2s (>5 h) and their association with mutations in ...Plasmodium falciparum Kelch-propeller protein K13. Here, we describe a P. falciparum laboratory cross of K13 C580Y mutant with C580 wild-type parasites to investigate ART response phenotypes in vitro and in vivo. After genotyping >400 isolated progeny, we evaluated 20 recombinants in vitro: IC50 measurements of dihydroartemisinin were at similar low nanomolar levels for C580Y- and C580-type progeny (mean ratio, 1.00; 95% CI, 0.62–1.61), whereas, in a ring-stage survival assay, the C580Y-type progeny had 19.6-fold (95% CI, 9.76–39.2) higher average counts. In splenectomized Aotus monkeys treated with three daily doses of i.v. artesunate, t
1/2 calculations by three different methods yielded mean differences of 0.01 h (95% CI, −3.66 to 3.67), 0.80 h (95% CI, −0.92 to 2.53), and 2.07 h (95% CI, 0.77–3.36) between C580Y and C580 infections. Incidences of recrudescence were 57% in C580Y (4 of 7) versus 70% in C580 (7 of 10) infections (−13% difference; 95% CI, −58% to 35%). Allelic substitution of C580 in a C580Y-containing progeny clone (76H10) yielded a transformant (76H10C580Rev) that, in an infected monkey, recrudesced regularly 13 times over 500 d. Frequent recrudescences of ART-treated P. falciparum infections occur with or without K13 mutations and emphasize the need for improved partner drugs to effectively eliminate the parasites that persist through the ART component of combination therapy.
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