A comparative study of microbial changes in dental plaque before and after single- and multiappointment treatments in patients with severe early childhood caries.

BACKGROUND: The status of dental caries is closely related to changes in the oral microbiome. In this study, we compared the diversity and structure of the dental plaque microbiome in children with severe early childhood caries (S-ECC) before and after general anaesthesia and outpatient treatment. METHODS: Forty children aged 3 to 5 years with S-ECC who had completed whole-mouth dental treatment under general anaesthesia (C1) or in outpatient settings (C2) were selected, 20 in each group. The basic information and oral health status of the children were recorded, and the microbial community structure and diversity of dental plaque before treatment (C1, C2), the day after treatment(C2_0D), 7 days after treatment (C1_7D, C2_7D), 1 month after treatment (C1_1M, C2_1M), and 3 months after treatment (C1_3M, C2_3M) were analysed via 16 S rRNA high-throughput sequencing technology. RESULTS: (1) The alpha diversity test showed that the flora richness in the multiappointment group was significantly greater at posttreatment than at pretreatment (P < 0.05), and the remaining alpha diversity index did not significantly differ between the 2 groups (P > 0.05). The beta diversity analysis revealed that the flora structures of the C1_7D group and the C2_3M group were significantly different from those of the other time points within the respective groups (P < 0.05). (2) The core flora existed in both the pre- and posttreatment groups, and the proportion of their flora abundance could be altered depending on the caries status of the children in both groups. Leptotrichia abundance was significantly (P < 0.05) lower at 7 days posttreatment in both the single- and multiappointment groups. Corynebacterium and Corynebacterium_matruchotii were significantly more abundant in the C1_1M and C1_3M groups than in the C1 and C1_7D groups (P < 0.05). Streptococcus, Haemophilus and Haemophilus_parainfluenzae were significantly more abundant in the C1_7D group than in the other groups (P < 0.05). CONCLUSION: A single session of treatment under general anaesthesia can cause dramatic changes in the microbial community structure and composition within 7 days after treatment, whereas treatment over multiple appointments may cause slow changes in oral flora diversity.

P450-Modified Ribosomally Synthesized Peptides with Aromatic Cross-Links.

Cyclization of linear peptides is an effective strategy to convert flexible molecules into rigid compounds, which is of great significance for enhancing the peptide stability and bioactivity. Despite significant advances in the past few decades, Nature and chemists' ability to macrocyclize linear peptides is still quite limited. P450 enzymes have been reported to catalyze macrocyclization of peptides through cross-linkers between aromatic amino acids with only three examples. Herein, we developed an efficient workflow for the identification of P450-modified RiPPs in bacterial genomes, resulting in the discovery of a large number of P450-modified RiPP gene clusters. Combined with subsequent expression and structural characterization of the products, we have identified 11 novel P450-modified RiPPs with different cross-linking patterns from four distinct classes. Our results greatly expand the structural diversity of P450-modified RiPPs and provide new insights and enzymatic tools for the production of cyclic peptides.

catena-Poly[[chlorido(1,10-phenanthro-line)copper(II)]-µ-{2-[(1S,3S)-3-acetyl-2,2-dimethyl-cyclo-but-yl]acetato}].

The title compound, [Cu(C(10)H(15)O(3))Cl(C(12)H(8)N(2))](n), is a one-dimensional coordination polymer. The Cu(II) atom is coordin-ated by a chloride ion, two N atoms from the 1,10-phenanthroline ligand, and a monodentate carboxyl-ate O atom from the pinononate anion, forming a CuN(2)ClO approximate square plane. A symmetry-generated pinononate O atom completes a square-based pyramidal geometry for the copper ion. The bridging 2-(3-acetyl-2,2-dimethyl-cyclo-but-yl)acetate anion leads to chains in the crystal propagating in [001]. Adjacent 1,10-phenanthroline rings form a dihedral angle of 39.4 (2)°.

(2E,5E)-2,5-Difurfurylidenecyclo-penta-none.

In the title mol-ecule, C(15)H(12)O(3), the three five-membered rings are nearly coplanar: the dihedral angles between the cyclopentanone ring and the furan rings are 3.5 (2) and 9.7 (2)°, and the two furan rings form a dihedral angle of 7.2 (2)°. In the crystal structure, weak inter-molecular C-H⋯O hydrogen bonds help to consolidate the crystal packing.

(2E,6E)-2,6-Difurfurylidenecyclo-hexa-none.

The complete mol-ecule of the title compound, C(16)H(14)O(3), is generated by crystallographic mirror symmetry, with two C atoms and one O atom lying on the mirror plane. The mol-ecule adopts an E configuration about the C=C bond and the dihedral angle between the furan rings is 16.1 (2)°.

Chlorido(5-formyl-2-hydroxy-phenyl-κC)mercury(II).

In the planar (r.m.s. deviation = 0.027 Å) title compound, [Hg(C(7)H(5)O(2))Cl], the Hg(II) atom shows a typical linear coordination by a C atom of the benzene ring and a Cl atom. Inter-molecular O-H⋯O hydrogen bonds are present in the crystal structure, resulting in chains propagating along the b axis. The crystal studied was a non-merohedral twin, with a twin ratio of 0.802 (2):0.198 (2).

Sodium (1R,2S,5S)-2-hydr-oxy-6,6-dimethyl-bicyclo-[3.1.1]heptane-2-carboxyl-ate penta-hydrate.

In the title compound, Na(+)·C(10)H(15)O(3) (-)·5H(2)O, the vertices of a distorted octa-hedron centred on the Na(+) cation are defined by six O atoms of water mol-ecules. The edge-sharing Na(H(2)O)(6) octa-hedra form a chain extended along the b-axis direction with adjacent Na(+) cations related by a twofold screw symmetry operation. The organic anion, which is not in close contact with the Na(+ )cation, is hydrogen-bonded to an uncoordinated water mol-ecule and to water mol-ecules of the Na(H(2)O)(6) octa-hedra.

Amycolamycins A and B, Two Enediyne-Derived Compounds from a Locust-Associated Actinomycete.

Two novel enediyne-derived natural products, amycolamycins A and B (1 and 2), were characterized from a locust-associated actinomycete Amycolatopsis sp. HCa4. Amycolamycins A and B contain a unique 2-(cyclopenta[a]inden-5-yl)oxirane core with suspected enediyne polyketide biosynthetic origin. Sequencing and analysis of the acm biosynthetic gene cluster allowed us to propose the biosynthetic pathway of 1 and 2. Moreover, amycolamycin A (1) was selectively cytotoxic to the M231 breast cancer cell line.