[Diagnosis and orthodontic treatment strategy of complete canine transposition].

Tooth transposition is a challenge for orthodontists, especially in correcting the order of teeth. At present, the literature on transposition canines mainly focuses on epidemiological studies and case reports, and no systematic treatment guidance has been formed. In this article, the definition and classification, epidemiology and etiology, imaging diagnosis, treatment and risk control of transposed canines are systematically described in order to provide reference for clinical practice.

[Effect of different mechanical loading on the expression of Notch signaling pathways in growing rabbits' condylar cartilage].

Objective: To investigate the effect of different mechanical loading on the expression of Notch-1, Notch-3, Jagged-1 and Delta-like-1 in growing rabbits' condylar cartilage. Methods: Sixty-four ten-days-old rabbits were randomly divided into experimental and control groups. The rabbits in the experimental groups were fed on a powder diet, while the control groups were fed on a solid diet. The animals were sacrificed after 2, 4, 6 and 8 weeks. Notch-1, Notch-3, Jagged-1 and Delta-like-1 gene and protein expressions were examined by HE, immunohistochemistry, Western blotting and quantitative real-time PCR. Results: At 2, 4, 6, 8 weeks, the anterior part of condylar cartilage in solid diet groups ([318.1±4.3], [342.4±2.6], [364.2±3.2], [380.7±6.0] mm, respectively) were thicker than those in powder diet groups ([275.4±2.6], [301.1±2.0], [322.3±3.3], [366.5±8.4] mm, respectively) (P<0.05). There was no significant difference between the two groups in the middle part (P>0.05). From 2 to 6 weeks, the posterior part of cartilage in solid diet groups ([444.1±1.5], [451.1±0.3], [476.4±5.7] mm, respectively) was thinner than those in power diet groups ([470.4±2.7], [494.3±2.9], [512.3±5.7] mm, respectively) (P<0.05). At 6 weeks, there were more mRNA expressions of Notch-3, Jagged-1 and Delta-like-1 in solid diet group than in power diet group (P<0.05). The Notch-1 protein could be found in all layers of condylar cartilage, especially in the surface of hypertrophic zone. The expressions of Notch-1, Notch-3, and Delta-like-1 protein were increased from 2 to 6 weeks, and decreased at 8 weeks. In solid diet groups, the protein expressions of Notch-1 (at 2, 4, 6, 8 weeks), Notch-3 (at 2, 4, 6 weeks), Jagged-1 (at 2, 4, 6 weeks) and Delta-like-1 (at 4, 6, 8 weeks) were greater than in power diet groups (P<0.05). Conclusions: Low masticatory loading may delay or inhibit the development of condylar cartilage and its growing factors such as Notch-1, Notch-3, Jagged-1 and Delta-like-1. Appropriate masticatory loading plays an important role in normal development of the condyle.

Deoxythioguanosine triphosphate impairs HIV replication: a new mechanism for an old drug.

Inhibition of HIV-1 reverse transcriptase (RT) and HIV protease are effective mechanisms for anti-retroviral agents, and the combined use of mechanistically different medications has markedly improved the treatment of HIV infected patients. The active metabolite of mercaptopurine and thioguanine (TG), deoxythioguanosine triphosphate, was shown to be incorporated into DNA by the polymerase function of HIV-1 RT and then to abrogate RNA cleavage by HIV-1 RNaseH. Treatment of human lymphocyte cultures with thioguanine produced substantial inhibition of HIV replication (IC(50)=0.035 microM, IC(95)=15.4 microM), with minimal toxicity to host lymphocytes (<10% at 15.4 microM TG, P<0.000005). Furthermore, low concentrations of TG and zidovudine were synergistic in inhibiting HIV replication in human lymphocytes (synergy volume=19 microM(2)%), without additive cytotoxicity to host lymphocytes. Thus, thiopurines are novel anti-retroviral agents that alter the DNA-RNA substrates for HIV RNaseH, thereby abrogating early stages of HIV replication.