[Comparison of clinical effects between periodontal endoscopy aiding subgingival debridement and flap surgery].

OBJECTIVE: To compare the clinical effects of periodontal endoscopy aiding subgingival debridement with periodontal flap surgery on residual deep pockets of chronic periodontitis. METHODS: In the single-blind randomized control clinical study, residual deep pockets of periodontitis patients were still existing when re-evaluation after receiving initial periodontal treatment.The pockets which were necessary for bone surgery or guided tissue regeneration surgery were excluded.The sites were divided into test group and control group randomly.Test group sites underwent periodontal endoscopy aiding debridement and control group sites had periodontal flap surgery.At the baseline and 3 months later, parameters, such as plaque index (PLI), bleeding index (BI), probing depth (PD), attachment loss (AL) were examined.Bone height was measured by parallelly digital X-ray dental film.Meanwhile, treatment time and comfort scale (visual analogue scale, VAS) were also recorded. RESULTS: At baseline, 41 proximal sites with residual deep pockets were enrolled (test sites=21, control sites=20).All the parameters were not significantly different between the two groups.PD decreased by (1.67±0.91) mm from (5.62±0.86) mm to (3.95±0.74) mm in test group and by (2.25±1.12) mm from (5.95±1.19) mm to (3.70±0.73) mm in control group significantly (P < 0.05).The difference between the two groups was not significant.The PD of all the sites decreased lower than 5 mm, meanwhile, 76% was lower than 4 mm in test group and 85% was lower than 4 mm in control group.The BI decreased by 0.81±0.93 in test group and 0.65±0.99 in control group significantly (P < 0.05).The difference between the two groups was not significant.The PLI showed a tendency of decrease more in test group and bone height showed a trend of decrease more in control group, however, the difference was not significant.The treatment time was almost the same.The patients felt more comfortable in the test group (VAS was 0.60±0.89) than the control group (VAS was 1.20±1.64), however, the difference was not significant. CONCLUSION: Periodontal endoscopy aiding subgingival debridement could improve periodontal status by reducing the PD and BI significantly in short term.The effect was almost the same with periodontal surgery and endoscopy treatment may decrease the necessity of surgery.Meanwhile, periodontal endoscopy has more comfortable treatment experience than flap surgery and does not need extra treatment time.

[Multivariable analysis of tooth loss in subjects with severe periodontitis over 4-year natural progression].

OBJECTIVE: To evaluate the characteristics of severe periodontitis with various number of tooth loss during 4-year natural progression, and to analyze the factors related to higher rate of tooth loss. METHODS: A total of 217 patients aged 15 to 44 years with severe periodontitis were included, who participated in a 4-year natural progression research. Data obtained from questionnaire survey, clinical examination and radiographic measurement. Tooth loss during 4-year natural progression was evaluated. The baseline periodontal disease related and caries related factors were calculated, including number of teeth with bone loss > 50%, number of missing molars, number of teeth with widened periodontal ligament space (WPDL), number of teeth with periapical lesions and etc. Characteristics of populations with various number of tooth loss and the related factors that affected higher rate of tooth loss were analyzed. RESULTS: In 4 years of natural progression, 103 teeth were lost, and annual tooth loss per person was 0.12±0.38. Nine patients lost 3 or more teeth. Thirty-four patients lost 1 or 2 teeth, and 174 patients were absent of tooth loss. Molars were mostly frequent to lose, and canines presented a minimum loss. The number of teeth with WPDL, with periapical lesions, with intrabony defects, with probing depth (PD)≥7 mm, with PD≥5 mm, with clinical attachment loss≥5 mm, with bone loss > 50% and with bone loss > 65% were positively correlated to number of tooth loss. Results from orderly multivariate Logistic regression showd that the number of teeth with bone loss > 50% OR=1.550), baseline number of molars lost (OR=1.774), number of teeth with WPDL (1 to 2: OR=1.415; ≥3: OR=13.105), number of teeth with periapical lesions (1 to 2: OR=4.393; ≥3: OR=9.526) and number of teeth with caries/residual roots (OR=3.028) were significant risk factors related to higher likelihood of tooth loss and multiple tooth loss. CONCLUSION: In 4 years of natural progression, the number of teeth with bone loss > 50%, baseline number of missing molars, number of teeth with WPDL, baseline number of teeth with periapical lesions and number of teeth with caries/residual roots were significantly related to higher risk of tooth loss and multiple tooth loss among Chinese young and middle-aged patients with severe periodontitis in rural areas.

[Molecular epidemiology of Listeria monocytogenes isolated from ready-to-eat food in 2017 in China].

Objective: To analyze the molecular characteristics of Listeria monocytogenes strains from ready-to eat food in China. Methods: A total of 239 Listeria monocytogenes strains isolated from ready-to-eat food in 2017, all strains underwent whole-genome sequencing (WGS) , and comparisons uncovered population structure derived from lineages, clonal complex, serogroups, antimicrobial susceptibility and virulence, which were inferred in silico from the WGS data. Core genome multilocus sequence typing was used to subtype isolates. Results: All strains were categorized into three different lineages, lineage Ⅱ was the predominant types in food, and IIa was the main serogroups. CC8, CC101 and CC87 were the first three prevalent CCs among 23 detected CCs, accounting for 49.4%. Only 4.6% (11 isolates) of tested strains harbored antibiotic resistance genes, which were mostly trimethoprim genes (7 isolates, 2.9%). All strains were positive for LIPI-1, and only a part of strains harbored LIPI-3 and LIPI-4, accounting for 13.8% (33 isolates) and 14.2% (34 isolates), respectively. ST619 carried both LIPI-3 and LIPI-4. 51.5% (123 isolates) of strains carried SSI-1, and all CC121 strains harbored SSI-2. Different lineages, serogroups and CCs can be separated obviously through cgMLST analysis, and 24 sublineages were highly concordant with CCs. Conclusion: Ⅱa was the main serogroups in ready-to-eat food isolates in China; CC8, CC101 and CC87 were the prevalent CCs, and CC87 isolates was hypervirulent isolates, cgMLST method can be adopted for prospective foodborne disease surveillance and outbreaks detection.

[Contamination and pathogenicity analysis of listeria monocytogenes in restaurant in Heilongjiang Province].

Objective: To study the contamination, serotype, pulsed field gel electrophoresis (PFGE) and drug resistance of listeria monocytogenes (L.monocytogenes) in the process of restaurant kitchens in Heilongjiang Province. Methods: Seventeen typical restaurants were selected from three cities in Heilongjiang Province in 2016, and 590 kitchen samples were collected and tested according to the national standard method. The serotype, pulsed field gel electrophoresis (PFGE) and drug resistance of isolated strains were analyzed. Results: L. monocytogenes was found in 104 of 590 of the samples analysed (17.63%). The isolates belong to six serotypes (1/2 a, 1/2 b, 1/2c, 3a, 3 b, 4 b) and self-condensing bacteria, and 57.38% (70 strains) of the strains belong to serotype 1/2b. Two highly pathogenic serotype 4b was detected for human listeria disease. The results of PFGE analysis show that the bacteria have cross-contamination in the environment, tools, equipment, food and personnel. The drug resistance results showed that 2 strains were resistant to tetracycline, 1 strain was resistant to erythromycin, 13 strains were intermediate to tetracycline, and 2 strains were resistant to tetracycline and erythromycin. Conclusion: There is a certain degree of L. monocytogenes cross-contamination in the catering kitchen in Heilongjiang Province. And an important serotype 4b that can cause human Listeria disease was detected.

Immune reconstitution in patients with acquired severe aplastic anemia after haploidentical stem cell transplantation.

Immune recovery (IR) after haploidentical stem cell transplantation (haplo-SCT) in severe aplastic anemia (SAA) patients remains relatively unknown. In this study, we examined immune cell subset counts and immunoglobulins in 81 SAA patients from day 30 to day 365 after haplo-SCT. Simultaneously, we determined which factors influence IR and analyzed the effects of immune cell subsets on transplant outcomes. We found that: (i) The reconstitution of different immune cell subsets occurred at different rates after haplo-SCT. Monocytes were the first to recover, followed by CD8+ T and CD19+ B cells, and finally CD4+ T cells. (ii) In the multivariate analysis, lower recipient age, female gender, high mononuclear cell counts in the graft and absence of CMV reactivation were associated with improved IR after transplant. (iii) A CD4/CD8 ratio less than 0.567 on day 30 post transplantation was associated with higher overall survival after haplo-SCT in SAA patients. In conclusion, SAA patients showed a faster recovery of monocytes and CD8+ T cells after haplo-SCT, whereas the recovery of the CD4+ T-cell subset was delayed. Our results may provide insight into methods for better predicting and modulating IR of SAA patients and subsequently improving outcomes after transplantation.

Heat shock protein 90 maintains the stability and function of transcription factor Broad Z7 by interacting with its Broad-Complex-Tramtrack-Bric-a-brac domain.

Heat shock protein 90 (Hsp90) is a highly conserved chaperone protein that interacts with various client proteins to mediate their folding and stability. The Broad-Complex-Tramtrack-Bric-a-brac (BTB) domain, also known as poxvirus and zinc finger (POZ) domain, exists widely in different proteins and is highly conserved. However, the stability mechanism of BTB domain-containing proteins has not been fully understood. Co-immunoprecipitation and a protein pull-down assay were performed to investigate the interaction between Hsp90 and the transcription factor Broad isoform Z7 (BrZ7) in vivo and in vitro. The middle domain of Hsp90 directly associated with the BTB domain of BrZ7. The Hsp90 inhibitor 17-(Allylamino)-17-demethoxygeldanamycin (17-AAG) interrupted the interaction between Hsp90 and BrZ7 and decreased the protein level of BrZ7 but did not affect the mRNA level of BrZ7. The addition of the proteasome inhibitor peptide aldehyde Cbz-leu-leu leucinal suppressed the 17-AAG-induced degradation of BrZ7. BTB domain deletion and 17-AAG treatment resulted in inhibition of BrZ7 function in gene expression in the 20-hydroxyecdysone and juvenile hormone pathways. These results reveal that the middle domain of Hsp90 associates with the BTB domain of BrZ7 to prevent BrZ7 degradation and maintain BrZ7 function in gene expression in the lepidopteran insect Helicoverpa armigera.

Microstructural fingerprints of phase transitions in shock-loaded iron.

The complex structural transformation in crystals under static pressure or shock loading has been a subject of long-standing interest to materials scientists and physicists. The polymorphic transformation is of particular importance for iron (Fe), due to its technological and sociological significance in the development of human civilization, as well as its prominent presence in the earth's core. The martensitic transformation α→ε (bcc→hcp) in iron under shock-loading, due to its reversible and transient nature, requires non-trivial detective work to uncover its occurrence. Here we reveal refined microstructural fingerprints, needle-like colonies and three sets of {112}<111> twins with a threefold symmetry, with tell-tale features that are indicative of two sequential martensitic transformations in the reversible α→ε phase transition, even though no ε is retained in the post-shock samples. The signature orientation relationships are consistent with previously-proposed transformation mechanisms, and the unique microstructural fingerprints enable a quantitative assessment of the volume fraction transformed.

Design and chance in the self-assembly of macromolecules.

The principles of self-assembly are described for naturally occurring macromolecules and for complex assemblies formed from simple synthetic constituents. Many biological molecules owe their function and specificity to their three-dimensional folds, and, in many cases, these folds are specified entirely by the sequence of the constituent amino acids or nucleic acids, and without the requirement for additional machinery to guide the formation of the structure. Thus sequence may often be sufficient to guide the assembly process, starting from denatured components having little or no folds, to the completion state with the stable, equilibrium fold that encompasses functional activity. Self-assembly of homopolymeric structures does not necessarily preserve symmetry, and some polymeric assemblies are organized so that their chemically identical subunits pack stably in geometrically non-equivalent ways. Self-assembly can also involve scaffolds that lack structure, as seen in the multi-enzyme assembly, the degradosome. The stable self-assembly of lipids into dynamic membraneous sheets is also described, and an example is shown in which a synthetic detergent can assemble into membrane layers.

The proteasome inhibitor bortezomib promotes mitochondrial injury and apoptosis induced by the small molecule Bcl-2 inhibitor HA14-1 in multiple myeloma cells.

Interactions between the small molecule Bcl-2 inhibitor HA14-1 and proteasome inhibitors, including bortezomib (Velcade; formerly known as PS-341) and MG-132, have been examined in human multiple myeloma cells. Sequential (but not simultaneous) exposure of MM.1S cells to bortezomib or MG-132 (10 h) followed by HA14-1 (8 h) resulted in a marked increase in mitochondrial injury (loss of DeltaPsim, cytochrome c, Smac/DIABLO, and apoptosis-inducing factor release), activation of procaspases-3, -8, and -9, and Bid, induction of apoptosis, and loss of clonogenicity. Similar interactions were observed in U266 and MM.1R dexamethasone-resistant myeloma cells. These events were associated with Bcl-2 cleavage, Bax, Bak, and Bad accumulation, mitochondrial translocation of Bax, abrogation of Mcl-1, Bcl-xL, and XIAP upregulation, and a marked induction of JNK and p53. Bortezomib/HA14-1 treatment triggered an increase in reactive oxygen species (ROS), which, along with apoptosis, was blocked by the free radical scavenger N-acetyl-L-cysteine (L-NAC). L-NAC also opposed bortezomib/HA14-1-mediated JNK activation, upregulation of p53 and Bax, and release of cytochrome c and Smac/DIABLO. Finally, bortezomib/HA14-1-mediated apoptosis was unaffected by exogenous IL-6. Together, these findings indicate that sequential exposure of myeloma cells to proteasome and small molecule Bcl-2 inhibitors such as HA14-1 may represent a novel therapeutic strategy in myeloma.

Crystal structure of an Xrcc4-DNA ligase IV complex.

A complex of two proteins, Xrcc4 and DNA ligase IV, plays a fundamental role in DNA non-homologous end joining (NHEJ), a cellular function required for double-strand break repair and V(D)J recombination. Here we report the crystal structure of human Xrcc4 bound to a polypeptide that corresponds to the DNA ligase IV sequence linking its two BRCA1 C-terminal (BRCT) domains. In the complex, a single ligase chain binds asymmetrically to an Xrcc4 dimer. The helical tails of Xrcc4 undergo a substantial conformational change relative to the uncomplexed protein, forming a coiled coil that unwinds upon ligase binding, leading to a flat interaction surface. A buried network of charged hydrogen bonds surrounded by extensive hydrophobic contacts explains the observed tightness of the interaction. The strong conservation of residues at the interface between the two proteins provides evidence that the observed mode of interaction has been maintained in NHEJ throughout evolution.

Conformational changes in serpins: II. The mechanism of activation of antithrombin by heparin.

Antithrombin, uniquely among plasma serpins acting as proteinase inhibitors in the control of the blood coagulation cascade, circulates in a relatively inactive form. Its activation by heparin, and specifically by a pentasaccharide core of heparin, has been shown to involve release of the peptide loop containing the reactive centre from partial insertion in the A sheet of the molecule. Here we compare the structures of the circulating inactive form of antithrombin with the activated structure in complex with heparin pentasaccharide. We show that the rearrangement of the reactive centre loop that occurs upon activation is part of a widespread conformational change involving a realignment of the two major domains of the molecule. We also examine natural mutants that possess high affinity for heparin pentasaccharide, and relate the kinetics of their interaction with heparin pentasaccharide to the structural transitions occuring in the activation process.

Topography of a 2.0 A structure of alpha1-antitrypsin reveals targets for rational drug design to prevent conformational disease.

Members of the serpin family of serine proteinase inhibitors play important roles in the inflammatory, coagulation, fibrinolytic, and complement cascades. An inherent part of their function is the ability to undergo a structural rearrangement, the stressed (S) to relaxed (R) transition, in which an extra strand is inserted into the central A beta-sheet. In order for this transition to take place, the A sheet has to be unusually flexible. Malfunctions in this flexibility can lead to aberrant protein linkage, serpin inactivation, and diseases as diverse as cirrhosis, thrombosis, angioedema, emphysema, and dementia. The development of agents that control this conformational rearrangement requires a high resolution structure of an active serpin. We present here the topology of the archetypal serpin alpha1-antitrypsin to 2 A resolution. This structure allows us to define five cavities that are potential targets for rational drug design to develop agents that will prevent conformational transitions and ameliorate the associated disease.

The conformational activation of antithrombin. A 2.85-A structure of a fluorescein derivative reveals an electrostatic link between the hinge and heparin binding regions.

Antithrombin is unique among the serpins in that it circulates in a native conformation that is kinetically inactive toward its target proteinase, factor Xa. Activation occurs upon binding of a specific pentasaccharide sequence found in heparin that results in a rearrangement of the reactive center loop removing constraints on the active center P1 residue. We determined the crystal structure of an activated antithrombin variant, N135Q S380C-fluorescein (P14-fluorescein), in order to see how full activation is achieved in the absence of heparin and how the structural effects of the substitution in the hinge region are translated to the heparin binding region. The crystal structure resembles native antithrombin except in the hinge and heparin binding regions. The absence of global conformational change allows for identification of specific interactions, centered on Glu(381) (P13), that are responsible for maintenance of the solution equilibrium between the native and activated forms and establishes the existence of an electrostatic link between the hinge region and the heparin binding region. A revised model for the mechanism of the allosteric activation of antithrombin is proposed.

The 2.0-A resolution crystal structure of a trimeric antibody fragment with noncognate VH-VL domain pairs shows a rearrangement of VH CDR3.

The 2.0-A resolution x-ray crystal structure of a novel trimeric antibody fragment, a "triabody," has been determined. The trimer is made up of polypeptides constructed in a manner identical to that previously described for some "diabodies": a VL domain directly fused to the C terminus of a VH domain-i.e., without any linker sequence. The trimer has three Fv heads with the polypeptides arranged in a cyclic, head-to-tail fashion. For the particular structure reported here, the polypeptide was constructed with a VH domain from one antibody fused to the VL domain from an unrelated antibody giving rise to "combinatorial" Fvs upon formation of the trimer. The structure shows that the exchange of the VL domain from antibody B1-8, a Vlambda domain, with the VL domain from antibody NQ11, a Vkappa domain, leads to a dramatic conformational change in the VH CDR3 loop of antibody B1-8. The magnitude of this change is similar to the largest of the conformational changes observed in antibody fragments in response to antigen binding. Combinatorial pairing of VH and VL domains constitutes a major component of antibody diversity. Conformationally flexible antigen-binding sites capable of adapting to the specific CDR3 loop context created upon VH-VL pairing may be employed by the immune system to maximize the structural diversity of the immune response.