Carbon nanotubes functionalized with sodium hyaluronate restore bone repair in diabetic rat sockets.

OBJECTIVE: We evaluated the effects of sodium hyaluronate (HY) and carbon nanotubes functionalized with HY (HY-CNT) on bone repair in the tooth sockets of diabetic rats. MATERIALS AND METHODS: Diabetes was induced by streptozotocin (50 mg kg(-1) i.v.), and the sockets were divided into normal control, diabetic control, diabetic treated with HY (1%), and diabetic treated with HY-CNT (100 µg ml(-1)) groups. The sockets were analyzed according to the percentage of bone formation and the number of cell nuclei. RESULTS: The percentage of bone trabeculae was lower in diabetic control animals (11.16 ± 5.10% vs 41.92 ± 6.34% in normal animals) after 14 days. Treating diabetic animals with HY or HY-CNT significantly increased the percentage of neoformed trabeculae (HY: 29.43 ± 3.29%; HY-CNT: 36.90 ± 3.07%). Moreover, the sockets of diabetic animals had an increased number of cell nuclei and HY or HY-CNT reduced this parameter. CONCLUSION: Our results indicate that HY and HY-CNT restore bone repair in the tooth sockets of diabetic rats, suggesting that these biomaterials are potential adjuvant therapies for the management of diabetes.

In vitro and in vivo evaluation of the biocompatibility of a calcium phosphate/poly(lactic-co-glycolic acid) composite.

This study assess the effects of bioceramic and poly(lactic-co-glycolic acid) composite (BCP/PLGA) on the viability of cultured macrophages and human dental pulp fibroblasts, and we sought to elucidate the temporal profile of the reaction of pulp capping with a composite of bioceramic of calcium phosphate and biodegradable polymer in the progression of delayed dentine bridge after (30 and 60 days) in vivo. Histological evaluation of inflammatory infiltrate and dentin bridge formation were performed after 30 and 60 days. There was similar progressive fibroblast growth in all groups and the macrophages showed viability. The in vivo study showed that of the three experimental groups: BCP/PLGA composite, BCP and calcium hydroxide (Ca(OH)(2)) dentin bridging was the most prevalent (90 %) in the BCP/PLGA composite after 30 days, mild to moderate inflammatory response was present throughout the pulp after 30 days. After 60 days was observed dentine bridging in 60 % and necrosis in 40 %, in both groups. The results indicate that understanding BCP/PLGA composite is biocompatible and by the best tissue response as compared to calcium hydroxide in direct pulp capping may be important in the mechanism of delayed dentine bridge after 30 and 60 days.

Screening for congenital hypothyroidism in extreme premature and/or very low birth weight newborns: the importance of a specific protocol.

BACKGROUND: Neonatal screening for congenital hypothyroidism (CH) in premature infants is not as well established as in term newborns regarding age and number of samples. AIMS: 1. To evaluate the effectiveness of the protocol recommended by the Neonatal Screening Program of the State of Minas Gerais (PETN-MG) for CH neonatal screening in very low birth weight premature infants. 2. To estimate the prevalence of delayed TSH elevation and thyroid function alterations in the target population. METHODS: TSH was assessed by ELISA on the 5th, 10th and 30th days of life in all newborns with gestational age <32 weeks and/or very low birth weight (VLB) (<1,500 g) in the period from October 2004 to September 2006. RESULTS: Out of the 14,462 newborns screened, 2,647 were premature with gestational age <32 weeks and/or VLB. Forty-four cases of altered TSH were found and 11 infants underwent treatment. Delayed TSH elevation was detected in 66% of altered cases. Five out of the 11 cases were detected in the second sample and five cases were only detected in the third sample. CONCLUSION: The high prevalence of thyroid function alterations that demanded treatment (1:242) and delayed TSH elevation in VLB premature infants reinforce the need for a specific protocol, based on retesting procedures, for CH neonatal screening.

Role of BMP-4 during tooth development in a model with complete dentition.

There are no reports in literature about roles of bone morphogenetic protein 4 (BMP-4) in tooth development in mammals with complete dentition (with all dental groups). The classical model of study is the mouse, which has distinctive incisor and molar patterns. The opossum Didelphis albiventris with five upper and four lower incisors, one canine, three premolars and four molars, on each side of the jaw, seems to be a convenient model for odontogenesis study. This investigation searched for similarities and differences in BMP-4 expression pattern between the opossum and the mouse. BMP-4 cDNA was obtained by RT-PCR and the expression pattern during molar tooth development was investigated by the immunoperoxidase method. Opossum BMP-4 mature protein has 95% of sequence similarity in relation to mouse and 94% to human. The BMP-4 expression pattern during opossum tooth development was suggestive of a role in dental organ initiation and morphogenesis.

Morphological changes and EGF expression in the granular convoluted tubule cells of submandibular glands of Trypanosoma cruzi infected rats.

We have previously demonstrated in rats that Chagas' disease affects the salivary glands, by promoting an enlargement of the submandibular gland. In order to further investigate possible functional alterations on infected submandibular glands, the objective of the present study was to analyze epidermal growth factor (EGF) expression on rat submandibular glands during Trypanosoma cruzi infection. Results demonstrated that infected rats presented lower levels of testosterone, and morphological changes in the granular convoluted tubule (GCT) cells of the submandibular glands, along with acinar enlargement and delayed ductal maturation at the developing granular ducts. Immunohistochemistry analysis additionally showed that only few cells immunolabelled with anti-EGF on infected rats during the acute phase of Chagas' disease, while after 64 and 90 days (chronic phase) of infection, EGF expression was similar to non-infected rats. The present findings suggest that at the acute phase of Chagas' disease, lower levels of testosterone may lead to a delayed maturation of GCT, which positively correlates with decreased EGF production by submandibular glands cells.

The role of tumor necrosis factor receptor type 1 in orthodontic tooth movement.

Orthodontic tooth movement is dependent on osteoclast activity. Tumor necrosis factor (TNF)-alpha plays an important role, directly or via chemokine release, in osteoclast recruitment and activation. This study aimed to investigate whether the TNF receptor type 1 (p55) influences these events and, consequently, orthodontic tooth movement. An orthodontic appliance was placed in wild-type mice (WT) and p55-deficient mice (p55(-/-)). Levels of TNF-alpha and 2 chemokines (MCP-1/CCL2, RANTES/CCL5) were evaluated in periodontal tissues. A significant increase in CCL2 and TNF-alpha was observed in both groups after 12 hrs of mechanical loading. However, CCL5 levels remained unchanged in p55(-/-) mice at this time-point. The number of TRAP-positive osteoclasts in p55(-/-) mice was significantly lower than that in WT mice. Also, there was a significantly smaller rate of tooth movement in p55(-/-) mice. Analysis of our data suggests that the TNFR-1 plays a significant role in orthodontic tooth movement that might be associated with changes in CCL5 levels.

The role of iNOS and PHOX in periapical bone resorption.

Nitric oxide (NO) and reactive oxygen species (ROS) are key molecules in resistance to pathogens. Little is known about their role in pathogenesis of periapical lesions. To address this issue, we induced periapical lesions in mice lacking nitric oxide synthase (iNOS(-/-)) or phagocyte oxidase (PHOX(-/-)). iNOS(-/-) mice expressed higher levels of IL-1ß, TNF-α, RANK, RANKL, and MCP-1 than C57BL/6 and PHOX(-/-). Apical thickening of the periodontal ligament was also greater in iNOS(-/-) compared with other groups. Interestingly, ROS production did not interfere in periapical lesion progression, but seemed to be essential for the appearance of multinucleated TRAP-positive cells. Thus, periapical lesion progression in iNOS(-/-) was associated with an imbalance of pro-inflammatory cytokines (IL-1ß and TNF-α), bone-resorptive modulators (RANK and RANKL), and MCP-1. We conclude that NO, but not ROS, controls progression of bone resorption in a murine experimental model of apical periodontitis.

Neuronal nitric oxide synthase-derived hydrogen peroxide is a major endothelium-dependent relaxing factor.

Endothelium-dependent vasorelaxation in large vessels is mainly attributed to Nomega-nitro-L-arginine methyl ester (L-NAME)-sensitive endothelial nitric oxide (NO) synthase (eNOS)-derived NO production. Endothelium-derived hyperpolarizing factor (EDHF) is the component of endothelium-dependent relaxations that resists full blockade of NO synthases (NOS) and cyclooxygenases. H2O2 has been proposed as an EDHF in resistance vessels. In this work we propose that in mice aorta neuronal (n)NOS-derived H2O2 accounts for a large proportion of endothelium-dependent ACh-induced relaxation. In mice aorta rings, ACh-induced relaxation was inhibited by L-NAME and Nomega-nitro-L-arginine (L-NNA), two nonselective inhibitors of NOS, and attenuated by selective inhibition of nNOS with L-ArgNO2-L-Dbu-NH2 2TFA (L-ArgNO2-L-Dbu) and 1-(2-trifluoromethylphehyl)imidazole (TRIM). The relaxation induced by ACh was associated with enhanced H2O2 production in endothelial cells that was prevented by the addition of L-NAME, L-NNA, L-ArgNO2-L-Dbu, TRIM, and removal of the endothelium. The addition of catalase, an enzyme that degrades H2O2, reduced ACh-dependent relaxation and abolished ACh-induced H2O2 production. RT-PCR experiments showed the presence of mRNA for eNOS and nNOS but not inducible NOS in mice aorta. The constitutive expression of nNOS was confirmed by Western blot analysis in endothelium-containing vessels but not in endothelium-denuded vessels. Immunohistochemistry data confirmed the localization of nNOS in the vascular endothelium. Antisense knockdown of nNOS decreased both ACh-dependent relaxation and ACh-induced H2O2 production. Antisense knockdown of eNOS decreased ACh-induced relaxation but not H2O2 production. Residual relaxation in eNOS knockdown mouse aorta was further inhibited by the selective inhibition of nNOS with L-ArgNO2-L-Dbu. In conclusion, these results show that nNOS is constitutively expressed in the endothelium of mouse aorta and that nNOS-derived H2O2 is a major endothelium-dependent relaxing factor. Hence, in the mouse aorta, the effects of nonselective NOS inhibitors cannot be solely ascribed to NO release and action without considering the coparticipation of H2O2 in mediating vasodilatation.