Morphometric study of the apical anatomy of C-shaped root canal systems in mandibular second molars

AIM

To investigate the apical anatomy of C-shaped canal systems in mandibular second molars by micro-computerized tomography (microCT) and stereomicroscopy.

METHODOLOGY

Forty-four permanent mandibular second molars with a C-shaped root canal systems from a native Chinese population were scanned at 100 microm intervals by microCT at a resolution of 30 x 30 microm. The apical 5 mm of each tooth was reconstructed three-dimensionally for visualization and classification of the canal configuration using Vertucci's criteria. The main and auxiliary (accessory) foramina were examined under a stereomicroscope.

RESULTS

Type IV and VIII canal configurations were most often found in the apical 5 mm of these canal systems. The prevalence of accessory canals, lateral canals, inter-canal communications and apical delta were 41%, 25%, 27% and 11%, respectively. Approximately 80% of C-shaped canals had 1-3 apical foramina; the prevalence of accessory foramina was about 48%. The mean distance between the main foramen and the anatomic root apex was 0.84 mm, and that between the accessory foramen and the apex was 1.61 mm. The mean (shortest and longest) diameters of major and accessory foramina were 0.19 - 0.32 mm and 0.07 - 0.10 mm, with a mean form factor of 0.73 and 0.82, respectively.

CONCLUSION

The apical anatomy of C-shaped root canal systems in mandibular second molars is extremely complex with many anatomical variations.

Immunogenicity and persistence of a targeted anti-caries DNA vaccine

We have previously reported that a targeted anti-caries DNA vaccine, pGJA-P, induced accelerated and increased antibody responses compared with a non-targeted anti-caries DNA vaccine. Recently, pGJA-P/VAX, a new targeted anti-caries DNA vaccine for human trials, was constructed by replacing the pCI vector used in the construction of pGJA-P with pVAX1, the only vector authorized by the US Food and Drug Administration in clinical trials. Here, we report on our exploration of the kinetics of the antibody responses generated following pGJA-P/VAX immunization and the persistence of pGJA-P/VAX at both the inoculation site and the draining lymph nodes. Intranasal vaccination of mice with pGJA-P/VAX induced strong antibody responses that lasted for more than 6 months. Furthermore, pGJA-P/VAX could still be detected at both the inoculation site and the draining cervical lymph nodes 6 months after immunization. Thus, the persistent immune responses are likely due to the DNA depot in the host, which acts as a booster immunization.

Expression and bioactivity of recombinant human lysozyme in the milk of transgenic mice

Human milk lysozyme is an important protein for innate immunity, but human breast milk is a fairly poor source for commercial production of this enzyme. Research on the expression of recombinant human lysozyme (rHlys) is therefore potentially valuable to the dairy industry. In this study, 2 different kinds of transgenic mice, PBC-hLY and PBC-sighLY, were generated and used as system models to express rHlys. Six lines of PBC-hLY transgenic mice with human lysozyme genomic DNA-based constructs were generated, and a maximum expression level of rHlys approaching 0.154 mg/mL was achieved. Antibacterial activity of the whey from PBC-hLY female transgenic mice was determined by a turbidimetric assay. Results showed that antibacterial activity of the whey was strongly enhanced, and confirmed that rHlys retained full activity. For rHlys to be secreted efficiently into the milk of transgenic mice, 5 lines of mice were also generated, in which the signal peptide DNA of bovine beta-casein was substituted for that of lysozyme in PBC-hLY transgenic mice. Compared with PBC-hLY transgenic mice, both the expression levels of rHlys and the antibacterial activity of the whey were much higher in the PBC-sighLY transgenic mice. The concentration of rHlys in one of these mice amounted to 1.405 mg/mL-3 times higher than the level in human whey. The antibacterial activity of the whey was also 3 times higher than that of human whey. The rHlys from both PBC-hLY and PBC-sighLY transgenic mice had the same antibacterial activity as human milk lysozyme. The effect of the signal peptide and copy numbers of the transgene on expression of rHlys was also evaluated. This work will certainly permit a better understanding of how mammary gland bioreactor systems can be applied to produce rHlys in other mammals, such as cattle.

Partial molecular characterization, polymorphism and chromosomal localization of the porcine PSMD4 gene

The complete coding sequence of porcine PSMD4 gene encoding proteasome 26S non-ATPase subunit 4 was obtained by the reverse transcriptase-polymerase chain reaction (RT-PCR) and deposited in GenBank nucleotide database (AY704418). The nucleotide sequence and the predicted protein sequence shared the high sequence identity with their mammalian counterparts. A G/A single nucleotide polymorphism in intron 9 detected as Hin6I PCR-restriction fragment length polymorphism (PCR-RFLP) shows allele frequency differences between Meishan, Erhualian, Tibetan, Large White and Duroc breeds. Analyses of somatic cell hybrid panel (SCHP) and radiation hybrid (IMpRH) panel revealed that PSMD4 gene maps to SSC 4q21-q23 and closely linked the SW512 (14 cR, LOD = 19.47).

Cooperative antitumor activity between the retinoid X receptor (RXR)-selective agonist bexarotene and EGFR-tyrosine kinase inhibitors in preclinical models of NSCLC

17073

Background: Gefitinib and erlotinib, small molecule inhibitors of the EGFR-tyrosine kinase (EGFR-TKI), can have antitumor activity in patients with advanced NSCLC. However, analysis of clinical samples and in vitro characterization of NSCLC cell lines has revealed EGFR mutations that correlate with the clinical responses. While EGFR-mutant cell lines are hypersensitive to EGFR-TKI-mediated growth inhibition and have a greater tendency to undergo apoptosis in response to EGFR inhibition, wild-type EGFR cell lines undergo growth inhibition only at high concentrations, and are resistant to apoptosis induction. Bexarotene (Targretin) is a RXR modulator with clinical activity enhancing survival in a subset of NSCLC patients. We have shown that bexarotene can suppress the growth of epithelial tumors by modulating the expression and function of the EGFR pathway. This study examined the effect of bexarotene/EGFR-TKI combinations in preclinical models of NSCLC, and evaluated the possible molecular mechanisms for cooperative antitumor activity between these agents. Results: Bexarotene enhanced the activity of gefitinib in most of the cell lines tested, and did so regardless of their EGFR mutation status or intrinsic sensitivity to gefitinib alone. Resistant lines were sensitized by the combination, which decreased gefitinib IC50s to clinically achievable concentrations. Bexarotene increased the pro-apoptotic activity of both gefitinib and erlotinib, an effect which was paralleled by enhanced repression of p-Akt and p-Her2 levels by the combinations. In ex vivo cultures of human NSCLC explant tissue, the addition of bexarotene enhanced the growth inhibitory activity of both gefitinib and erlotinib. Finally, combinations of bexarotene and EGFR-TKI produced growth inhibition of TKI-resistant A427 NSCLC xenograft tumors that was superior to either agent alone. Conclusions: These results indicate that bexarotene can sensitize NSCLC cells which are unresponsive to the effects of EGFR-TKIs, resulting in cooperative growth inhibition and apoptosis induction. Combination therapy using bexarotene in conjunction with EGFR-TKIs may provide a powerful new therapeutic strategy.

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Efficacy of emergent transcatheter transplantation of stem cells for treatment of acute myocardial infarction (TCT-STAMI)

OBJECTIVE

To study whether emergent intracoronary autologous bone marrow cell transplantation (BMT) is applicable for the treatment of acute myocardial infarction (AMI).

METHODS

20 patients admitted within 24 h after the onset of a first AMI were randomly allocated to receive intracoronary autologous BMT (n = 10) or bone marrow supernatant (controls, n = 10) immediately after primary percutaneous coronary intervention. Left ventricular ejection fraction (LVEF), left ventricular end diastolic internal diameter (LVDd) and myocardial perfusion defect scores were examined respectively by echocardiography and single-photon emission computed tomography at one week and six months after AMI.

RESULTS

From one week to six months after AMI, LVEF was enhanced from mean 53.8 (SD 9.2)% to 58.6 (9.9)% (p < 0.05) in the BMT group but was unchanged in the control group (58.2 (7.5)% v 56.3 (3.5)%, p > 0.05); LVDd remained unchanged (52.5 (2.8) v 52.1 (3.2) mm, p > 0.05) in the BMT group but was significantly enlarged in the control group (50.4 (6.0) v 55.2 (7.1) mm, p < 0.05). Additionally, myocardial perfusion defect scores decreased from 21 (11) to 13 (10) (p < 0.01) in the BMT group but were unchanged in the control group (20 (14) v 17 (15), p > 0.05).

CONCLUSION

Emergent intracoronary transplantation of bone marrow mononuclear cells after AMI is practicable, and it improved cardiac function, prevented myocardial remodelling and increased myocardial perfusion at six months' follow up.

Sequence identification, tissue distribution, mapping and polymorphism of the porcine sar1b gene

The predicted full-length cDNA sequence of the porcine Sar1b gene was characterized by assembling pig ESTs from GenBank. The coding sequence (CDS) shares high sequence identity with the corresponding sequences of human (93%) and mouse (91%). The reverse transcription-polymerase chain reaction (RT-PCR) displayed that porcine Sar1b gene is expressed in all eight tissues (liver, small intestine, stomach, heart, lung, spleen, muscle and fat). Analysis of the somatic cell hybrid panel (SCHP) and the INRA-University of Minnesota porcine radiation hybrid (IMpRH) panel indicated the gene maps to SSC2 (1/2 q24)-q29 and most closely links to the interleukin-4 (IL4) gene. One base-pair deletion polymorphism in the 3' untranslated region (UTR) detected by PCR-single strand conformational polymorphism (PCR-SSCP) analysis shows allele frequency differences between Meishan, Yushan Black, Dahuabai, Qingping, Tibetan, Landrace, Large White and Duroc. The association analysis using pigs of Tongcheng, Landrace x (Large White x Tongcheng) and Large White x (Landrace x Tongcheng) suggested that the deletion polymorphism was associated with the porcine muscle pH value.

Evaluation of the accuracy of three electronic apex locators using glass tubules

AIM

To evaluate the accuracy of three different electronic apex locators (EALs) using glass tubules.

METHODOLOGY

Forty-eight glass tubules with different diameters and an agar model were used to mimic root canals. A size 15 stainless steel K-file was used as the measuring electrode. The Root ZX, Propex and Neosono Ultima EZ were used to measure the tubule length with tubules dry, or filled with 0.9% NaCl, 3% H(2)O(2), 2.5% NaOCl or 17% EDTA. The distance between the real length (RL) and measured length (ML) of the tubules was recorded. The range of RL +/- 0.5 mm and RL +/- 1 mm was used to evaluate the accuracy of the EALs. Results were subject to correlation analysis and Friedman's test.

RESULTS

In dry tubules, the accuracy of Root ZX was 75-91.7% for RL +/- 0.5 mm and 100% for RL +/- 1 mm, whilst the measurements of the other two EALs were all within the RL +/- 0.5 mm. No influence from the increase in tubule diameter on the accuracy of all three EALs was observed in dry tubules. In tubules filled with electrolyte, the accuracy of the Root ZX decreased as tubule diameter increased (R(d) > 0, P < 0.05). The RL-ML distance recorded by Propex was inversely related to the tubule diameter (R(d) < 0, P < 0.05). The accuracy of Propex was 75-100% for RL +/- 0.5 mm and 100% for RL +/- 0.5 mm when the tubule diameter was not more than 0.80 mm, but decreased in tubules with diameter over 0.80 mm and filled with 2.5% NaOCl or 17% EDTA. Nearly, all the measurements (except for six tubules) using Neosono Ultima EZ were within 1 mm shorter than RL despite the contents in tubules and the increase of tubule diameter.

CONCLUSIONS

The accuracy of the Root ZX decreased as the tubule diameter increased when tubules were filled with electrolytes. The electrolytes in the tubules decreased the accuracy of Propex when the tubule diameter was large. The electrolytes in tubules and tubule diameter had no influence on the accuracy of Neosono Ultima EZ. The Propex and Neosono Ultima EZ were more accurate than the Root ZX under various conditions in this laboratory study.

Comparison of BMD precision for Prodigy and Delphi spine and femur scans

INTRODUCTION

Precision error in bone mineral density (BMD) measurement can be affected by patient positioning, variations in scan analysis, automation of software, and both short- and long-term fluctuations of the densitometry equipment. Minimization and characterization of these errors is essential for reliable assessment of BMD change over time.

METHODS

We compared the short-term precision error of two dual-energy X-ray absorptiometry (DXA) devices: the Lunar Prodigy (GE Healthcare) and the Delphi (Hologic). Both are fan-beam DXA devices predominantly used to measure BMD of the spine and proximal femur. In this study, 87 women (mean age 61.6+/-8.9 years) were measured in duplicate, with repositioning, on both systems, at one of three clinical centers. The technologists were International Society for Clinical Densitometry (ISCD) certified and followed manufacturer-recommended procedures. All scans were acquired using 30-s scan modes. Precision error was calculated as the root-mean-square standard deviation (RMS-SD) and coefficient of variation (RMS-%CV) for the repeated measurements. Right and left femora were evaluated individually and as a combined dual femur precision. Precision error of Prodigy and Delphi measurements at each measurement region was compared using an F test to determine significance of any observed differences.

RESULTS

While precision errors for both systems were low, Prodigy precision errors were significantly lower than Delphi at L1-L4 spine (1.0% vs 1.2%), total femur (0.9% vs 1.3%), femoral neck (1.5% vs 1.9%), and dual total femur (0.6% vs 0.9%). Dual femur modes decreased precision errors by approximately 25% compared with single femur results.

CONCLUSIONS

This study suggests that short-term BMD precision errors are skeletal-site and manufacturer specific. In clinical practice, precision should be considered when determining: (a) the minimum time interval between baseline and follow-up scans and (b) whether a statistically significant change in the patient's BMD has occurred.

Polymorphism detection of porcine PSMC3, PSMC6 and PSMD3 genes and their association with partial growth, carcass traits, meat quality and immune traits

PSMC3, PSMC6 and PSMD3 genes encode the proteasome 26S ATPase subunit 3, subunit 6 and the non-ATPase subunit 3, respectively, and exert the function in antigen processing and presentation. So these three genes were considered as the candidate genes that have the effect on porcine production and immune traits in this study. Genetic variations of these three genes were investigated and the single nucleotide polymorphism-based (SNPs-based) association analyses were studied initially. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) revealed that there is a MvaI polymorphic site in intron3 of PSMC3 gene and a MboI polymorphic site within intron 5 of PSMC6 gene, as well as a RsaI polymorphic site within exon 10 of the PSMD3 gene. χ2 analysis presented that allele frequencies differed among four breeds (Meishan, Erhualian, Qingping pig and Duroc) at PSMC3 and PSMD3 loci (P < 0.01). Association analysis showed that the PSMC3 gene has an effect on average backfat thickness (P < 0.01), total erythrocytes (P < 0.01) and hematocrit (P < 0.01), and there is a significant association between the PSMD3 genotypes and the mean corpuscular volume. PSMC6 has no effect on the production and immune traits we studied. Key words: Porcine, PSMC3, PSMC6, PSMD3, polymorphism, association analysis

PRNP polymorphisms in Chinese ovine, caprine and bovine breeds

Transmissible spongiform encephalopathy (TSE) is a neurodegenerative disorder in humans and animals. Polymorphisms and mutations in the prion protein (PRNP) gene have been associated with the incidence of natural and experimental TSE and the incubation period length. In this study, we determined PRNP polymorphisms in Chinese ovine, caprine and bovine breeds using 400 samples from 13 ovine and caprine breeds and 250 samples from nine bovine breeds. In the ovine and caprine PRNP gene, we found five previously unreported amino acid polymorphisms and two silent nucleotide alterations. In bovine PRNP, we found eight previously unreported amino acid polymorphisms and six silent nucleotide alterations.