Preliminary X-ray crystallographic analysis of SMU.2055 protein from the caries pathogen Streptococcus mutans.

The SMU.2055 gene from the major caries pathogen Streptococcus mutans is annotated as a putative acetyltransferase with 163 amino-acid residues. In order to identify its function via structural studies, the SMU.2055 gene was cloned into the expression vector pET28a. Native and SeMet-labelled SMU.2055 proteins with a His(6) tag at the N-terminus were expressed at a high level in Escherichia coli strain BL21 (DE3) and purified to homogeneity by Ni(2+)-chelating affinity chromatography. Diffraction-quality crystals of SeMet-labelled SMU.2055 were obtained using the sitting-drop vapour-diffusion method and diffracted to a resolution of 2.5 A on beamline BL17A at the Photon Factory, Tsukuba, Japan. The crystals belong to the orthorhombic space group C222(1), with unit-cell parameters a = 92.0, b = 95.0, c = 192.2 A. The asymmetric unit contained four molecules, with a solvent content of 57.1%.

[Methods of BMP immobilization and evaluation for Ti-based dental implant surface modification].

Ti-based biomaterial has been widely used as dental and bone implant material although its bioactivity still needs improvement especially for dental implant. The bone morphogenetic proteins(BMPs) bound to Ti-based materials will attract the mesenchymal stem cells to differentiate into osteoblast cells, which benefits the response to the protein-material surface, and finally leads to new bone formation. Several methods including physically mixing, coating, plasma immobilization and cross-linking were used to investigate how BMPs bind to Ti-based biomaterials. The latest research papers are focused on the structure and function of BMPs, and the methods to bind BMPs to Ti-based biomaterial and the evaluation methods after protein immobilization are reviewed in this paper.

HeLa-CCL2 cell heterogeneity studied by single-cell DNA and RNA sequencing.

The HeLa cells are the earliest and mostly used laboratory human cells for biomedical particularly cancer research. They were derived from a patient's cervical cancerous tissue, and are known for their heterogeneous cellular origin and variable genomic landscapes. Single-cell sequencing techniques with faithful linear and uniformly amplified genomes (DNA) and transcriptomes (RNA) may facilitate the study of cellular differences at the individual cell level. In this work, we have performed single-cell DNA and RNA sequencing with HeLa-CCL2 cells to study their heterogeneity. We have studied the complexity of copy number variations (CNVs) of HeLa-CCL2 genome at the single cell level, and revealed the transcriptomic heterogeneity of HeLa-CCL2. We also analyzed the relationship between genome and transcriptome at the single-cell level, and found overall correlation between CNV and transcriptome expression patterns. Finally, we concluded that although single-cell sequencing techniques are applicable to study heterogeneous cells such as HeLa-CCL2, the data analyses need to be more careful and well controlled.

Clinical investigation for bilateral cleft lip repair: modified functional bilateral cleft lip cheilorrhaphy.

PURPOSE: To obtain better operative results, a modified functional bilateral cleft lip (BCL) cheilorrhaphy was designed and used on 131 BCL patients to evaluate the clinical effectiveness in this clinical investigation. A new surgical method would be provided for BCL patients. PATIENTS AND METHODS: Based on the experiences and advantages of the commonly used self-longation and elongation surgical methods for BCL repair, a new surgical method was designed for BCL patients. During the operation, this modified functional BCL cheilorrhaphy emphasized the operative design, anatomy and reposition of musculus orbicularis orbis, management of the maxilla, and reparation of vermilion of the lip. This method was used to repair 131 BCL patients, and the conditions and results of errhysis, swelling, and healing of tresis vulnus were observed and evaluated. RESULTS: This modified functional BCL cheilorrhaphy was used successfully from January 2002 to July 2005 on 131 BCL patients. The wounds of all patients with BCL who joined this study healed very well without any hematoma, infection, or wound decohesion. All of the patients showed symmetric peak of Cupid's bow, obvious philtrum notch, full vermilion of the lip, little scarring, and satisfactory contour. During functional activity, bilateral upper lip was symmetric, coordinated, and balanced. CONCLUSIONS: The clinical results showed that modified functional BCL cheilorrhaphy may be accepted as a good selective surgical technique for BCL patients, and is worth generalization and application.

Protein preparation and preliminary X-ray crystallographic analysis of a putative glucosamine 6-phosphate deaminase from Streptococcus mutants.

The SMU.636 protein from Streptococcus mutans is a putative glucosamine 6-phosphate deaminase with 233 residues. The smu.636 gene was PCR-amplified from S. mutans genomic DNA and cloned into the expression vector pET-28a(+). The resultant His-tagged fusion protein was expressed in Escherichia coli and purified to homogeneity in two steps. Crystals of the fusion protein were obtained by the hanging-drop vapour-diffusion method. The crystals diffracted to 2.4 A resolution and belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 53.83, b = 82.13, c = 134.70 A.

Surgical repair of hard palate cleft with absorbable membrane: the new surgical technique and its clinical application.

This study evaluated a new surgical technique with absorbable membrane to repair hard palate cleft without extensive mobilisation of the mucoperiosteum. From 2001 to 2002, 32 selected patients with complete unilateral clefts underwent this surgical operation. The traditional flap surgical operation was performed at the soft palate, uvula and anterior alveolar cleft. The absorbable membrane was implanted to the hard palate cleft gap to guide the regeneration of the mucoperiosteum. The patients were followed up for 1-6 months after the operation. The speech assessment was carried out 12 months after the operation. Of 32 patients, 30 were successfully operated by this method and no obvious complications occurred. Primary healing on tissue defect of hard palate was obtained in 27 patients and secondary healing in 3 patients. Eighty percent of the 30 patients had good or excellent speech 12 months after the operation. The operation failed in 2 patients. The surgical technique with absorbable membrane to repair hard palate appears to have several valuable advantages including the decreased area of the hard palate involved and favourable outcome for speech in the majority of cases.

[Study on chronic toxicity to rats of implantation of super-high molecular weight polylactate].

OBJECTIVE: To make sure whether super-high molecular weight polylactate is toxic to the body after it has been implanted into the body for a long period. METHODS: We implanted super-high molecular weight polylactate into the rats and took the specimens of blood at 3, 6, 9, 12 months after the operation. The changes of proteins, electrolyte, enzyme and other indices were observed. At the same time, the tissue around the implants were taken out to carry out the histological observation. RESULTS: At 3, 6, 9, 12 months after the operation, the levels of albumin, globulin, total bilirubin, direct bilirubin, triglyceride, glucose, K+, Na+, Cl-, Ca2+, alkaline phosphatase, glutamic-pyruvic transaminase in the blood plasma were all in the normal range; there were no significant differences between the experimental group and the control group. The level of lactate dehydrogenase increased slightly, but there was no statistically significant difference between the experimental group and the control group. There were no non-reversible immune rejection around the implants in the histological observation. CONCLUSION: Super-high molecular weight polylactate is not toxic to the body after it has been implanted into the animals for a long period.

[Ultrastructure of poly-DL-lactic acid as GTR membrane of soft tissue defects in goats palates].

OBJECTIVE: To study the ultrastructure changes of PDLLA as GTR membrane of soft tissue defects in the palates of goats. METHODS: To establish penetrating rectangle palate defects in 8 goats. PDLLA membranes were implanted into the defect areas to guide the regeneration of the soft tissue defects. In 1, 2, 4, 6 months after the operation, the membranes were observed with scanning electron microscope. RESULTS: The surface of PDLLA membrane was regular network before implantation. 1 month after the implantation, the edge of network became blunt. 2 months after the implantation, the surface of PDLLA membrane became coarse and irregular. 4 months after the implantation, PDLLA membrane network collapsed. 6 months after the implantation, PDLLA degraded into scraggly accumulation. CONCLUSION: PDLLA membrane supplies good supporting function during concrescence of the soft tissue defects. PDLLA gradually loses mechanic intensity and is absorbed.

[Experimental study on the reconstruction of mandibular defects with a new bioactive artificial bone nano-hydroxyapatite/polyamide-66 in dogs].

OBJECTIVE: This study was designed to investigate reconstruction of segmental defect in the mandible using a new bionic materials of nano-hydroxyapatite -polyainides-66 (n-HA/PA66). METHODS: Two defects (15 mm x 10 mm x 5 mm) were created in the mandibular bodies of dogs. One of defects was reconstructed with n-HA/PA66, another not repaired as a blank control. At 2, 4, 8, 12, 16 weeks after operation. Evaluation of effects of n-HA/PA66 on reconstruction of the mandibular defects was carried out by means of radiography and histology. RESULTS: From 2 to 8 weeks after operation, some fiber tissue grew into the space between n-HA/PA66 and mandibular bone. The ossification was observed at 12 weeks post-operation. At 16 weeks, the n-HA/PA66 was connected directly to the mandibular bone by the newborn bone. CONCLUSIONS: The new artificial bone of n-HA/PA66 has the effects of osteoconduction and osteoinduction, with a good biocompatibility and is an ideal bone substitute material for reconstruction of mandibular defect.

[Influence of super high molecular weight poly D,L-lactic acid on viability and new bone formation of osteoblasts].

OBJECTIVE: To investigate the influence of the viability and new bone formation of osteoblasts by the super high molecular weight poly D,L-lactic acid (SHMW-PDLLA). METHODS: 1. The osteoblasts derived from neonatal rat were grown and maintained at steep of SHMW-PDLLA and normal culture medium. The viability and function of the osteoblasts were measured with MTT array. 2. The plate and screws made of SHMW-PDLLA were implanted and fixed at the artificial fractured mandible of dogs. Specimens were gained at 3 and 6 months and examined with macroscopy and SEM. RESULTS: 1. There is no significant difference of OD values between the experimental group and the control group (P > 0.05). The SHMW-PDLLA isn't toxic to osteoblast at 1 week and 2 weeks, and the toxicity is 3% at 3 days. 2. There were a lot of new bone formed between the implanted SHMW-PDLLA plate and bone tissues under SEM. CONCLUSION: SHMW-PDLLA hasn't pathological influence on the viability and new bone formation of osteoblasts and it is feasible in tissue engineering of bone.

[Repair of hard cleft palate with absorbable membranes made by poly-DL-lactic acid: a feasibility study].

OBJECTIVE: To investigate the feasibility and clinical results of applying poly-DL-lactic acid (PDLLA) biomembranes in cleft palate repair. METHODS: 68 cleft palate patients were divided into study group and control group. The traditional surgical method was used to control group to close the soft cleft palate, and the PDLLA biomembrane was used to study group and implanted into the surgical gap between the periosteum and bone at the hard palate, and fixed with suture. The duration, blood loss at operation, post-operative complication, wound healing and recovery were recorded and compared to conventional cleft palate repair. RESULTS: Operations were successfully completed on all 34 patients. Wound healing of soft palate and uvula was uneventful with no incidence of fistula or dehiscence. The primary healing on tissue defect of hard palate occurred in 29 patients, secondary healing occurred in 3 patients, permanent fistula between the oral cavity and the nasal cavity occurred in only one patients, and 3 patients left over fistula on alveolar process. Compared to traditional cleft palate repair, blood loss and incidence of fistula on alveolar process were decreased; the average surgical time was 89.25 minutes and was not prolonged; and there was no significant increase in post-operative complication. CONCLUSION: Hard cleft palate repair with PDLLA biomembranes is safe, simple and practical with good clinical results and is beneficial to minimize the bad influences towards the development and growth for maxilla of cleft palate patients.

[Guided reconstruction of soft tissue defects of the palate with n-HA/PA66 plates: an experimental study in goats.].

PURPOSE: To evaluate the effect of n-HA/PA66 plate as a guided implant for the regeneration of the soft tissue defects in palatal region of goats. METHODS: 12 goats were divided into experimental group and control group at random. 18.0 mm x 14.0 mm soft tissue defect and 15.0 mm x 13.0 mm hard tissue defect were formed artificially in hard palate. n-HA/PA66 plates were implanted to the defect in the experimental group. The tissue regeneration in the defects was observed and the structure of regenerating tissue was analyzed by histology. RESULTS: The mucoperiosteal tissue in the experimental group regenerated along the n-HA/PA66 plates and the mucoperiosteal defects were closed in 6 weeks. The soft and hard tissues were not closed up in control group in 6 weeks. CONCLUSION: n-HA/PA66 plates can guide the regeneration of mucoperiosteal tissue to close the palatal defects.