Bone densitometry in the evaluation of the results obtained with the use of bovine BMP in spine arthrodesis in rabbits

The object of this study is to evaluate the use of the bone densitometry as an evaluation method of the bone increment observed when we used bovine BMP in intertransverse arthrodesis of the rabbits' lumbar spine. Since the discovery of the BMP bone inductive properties, countless experimental models have been proposed. This caused the need of setting up evaluation methods to make possible a better understanding of the found results. Twenty female rabbits from New Zealand, divided in two groups, were submitted to the intertransverse arthrodesis of the lumbar column, segment L5/L6, posterior side. In the first group it was used autologous graft and in the second an association of autologous graft with biocompound (bovine BMP, 1.0 mg and hydroxyapatite, 9.0 mg). The animals were maintained in captivity, isolated and after 15 weeks submitted to the execution of bone densitometry by computerized tomography. 268 bone density measures of the normal bone, 134 measures of the newly formed bone by the association of the isolated autologous graft and 134 measures of the newly formed bone by the association autologous graft and BMP were obtained, what demonstrated a significant bone increment after statistical analysis (p=0.034) of the BMP/HAP group, when compared to the control group. We found this same variation of bone density analyzing the normal bone. The bone densitometry accomplished by the computerized tomography is an alternative method to assess the results when the BMP is used in experimental studies. Further studies should be accomplished for better understanding of the bone density variation found when the measures of the normal bone in the two groups are compared.As BMPs, proteínas indutoras de crescimento ósseo, desde o início de sua utilização, têm sido avaliadas em diferentes modelos experimentais objetivando determinar sua eficácia, sendo necessário o estabelecimento de métodos de avaliação que permitam melhor compreensão dos resultados. OBJETIVO: Este estudo tem por objetivo avaliar a utilização da densitometria óssea como método de avaliação do incremento ósseo observado quando da utilização de BMP bovina em artrodeses intertransversas da coluna lombar de coelhos. MÉTODOS: Foram utilizados dois grupos de dez coelhos neozelandeses fêmeas, submetidos a artrodese intertransversa da coluna lombar, segmento L5/L6, por via posterior. No primeiro grupo foi utilizado enxerto homólogo e no segundo a associação de enxerto homólogo com biocomposto (BMP bovino, 1,0 mg e hidroxiapatita, 9,0 mg). Os animais foram acompanhados por 15 semanas, isolados em cativeiro e avaliados diariamente por veterinário sob o ponto de vista clínico e neurológico e, posteriormente, submetidos à realização de densitometria óssea por tomografia computadorizada. RESULTADOS: Foram obtidas 268 medidas de densidade óssea do osso normal, 134 medidas do osso neoformado de enxerto homólogo isolado e 134 medidas do osso neoformado pela associação enxerto homólogo e BMP. Esses valores foram submetidos à análise estatística que demonstrou incremento ósseo significativo (p=0,034) do grupo BMP/HAP, quando comparado ao grupo controle. Os valores de densidade óssea do osso normal foram submetidos à mesma análise estatística onde se encontrou resultado semelhante. CONCLUSÃO: A densitometria óssea realizada pela tomografia computadorizada apresenta-se como método alternativo para avaliação de resultados quando utilizado BMP em estudos experimentais. Estudos subseqüentes deverão ser realizados para melhor entendimento da variação de densidade óssea encontrada quando da comparação das medidas do osso normal nos dois grupos.Universidade Federal de São Paulo (UNIFESP)Universidade Federal de São Paulo (UNIFESP) Departamento de Ortopedia e TraumatologiaUniversidade de São Paulo Faculdade de Odontologia de BauruUniversidade São Francisco Serviço de Ortopedia e TraumatologiaUNIFESP, Depto. de Ortopedia e TraumatologiaSciEL

Phosphatase activity characterization on the surface of intact bloodstream forms of Trypanosoma brucei

Procyclic forms of Trypanosoma brucei possess a phosphatase activity on their external cell surface. This activity, while it dephosphorylates [P-32]phosphocasein, is inhibited weakly by NaF and tartrate but strongly by vanadate. in this work, we describe the presence of an external phosphatase activity in intact bloodstream forms of T brucei. With p-nitrophenyl phosphate (pNPP) as substrate, these intact cells produced 3-5 nmol pNP min(-1) mg(-1), linearly for up to at least 30 min. the activity was not significantly increased by Mg2+, Mn2+, Ca2+ and Co2+, but was inhibited by vanadate, NaF, p-chloromercuribenzoate and Zn2+ and was insensitive to okadaic acid. Membrane-enriched fractions of parasites contained an acid phosphatase activity, with a pH optimum in the range of 4.5-5.5. This activity hydrolyzed phosphotyrosine (40 nmol phosphate min(-1) mg(-1)) better than phosphothreonine or phosphoserine. Partial purification of this phosphatase yielded a single activity band following gel electrophoresis, a K-m value of 0.29 mM with pNPP and was insensitive to the Fe2+/H2O2/ascorbate system. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.Universidade Federal de São Paulo, Dept Bioquim, BR-04023900 Sao Carlos, SP, BrazilUniv São Paulo, Fac Odontol, Dept Ciencias Biol, Bauru, SP, BrazilUniv Fed Rio de Janeiro, Inst Ciencias Biol, Dept Bioquim, Rio de Janeiro, RJ, BrazilUniv Estadual Campinas, Inst Biol, Dept Bioquim, BR-13083970 Campinas, SP, BrazilUniversidade Federal de São Paulo, Dept Bioquim, BR-04023900 Sao Carlos, SP, BrazilWeb of Scienc

Effect of sucrose-containing gum and fluoridated dentifrice on in situ remineralization of caries lesions

Este trabalho objetivou avaliar a remineralização de lesões iniciais de cárie in situ em esmalte bovino. Produziram-se as lesões artificialmente com o uso de solução desmineralizante, fixando-as na região correspondente à superfície lingual de primeiros molares inferiores, através de aparelhos removíveis, em seis voluntários com idades entre 18 e 22 anos, seguindo-se três períodos experimentais de uma semana. No primeiro período (grupo controle), realizou-se a escovação com dentifrício sem flúor, 4 vezes ao dia, após as refeições; no segundo (grupo I), procedeu-se à escovação com dentifrício contendo 1.500 ppm de flúor na forma MFP, 4 vezes ao dia, após as refeições; e no terceiro (grupo II), escovação com dentifrício sem flúor e utilização de goma de mascar contendo 60% de sacarose, por 20 minutos, 4 vezes ao dia, após as refeições. Antes e depois de cada tratamento, realizaram-se ensaios de dureza Vickers (200 g), obtendo-se o percentual de remineralização de cada lesão (alfa). O grupo controle sofreu uma desmineralização de 2,78%, e os grupos I e II, remineralização de 3,36% e 5,21%, respectivamente. A análise estatística através dos testes de Kruskal-Wallis e de Miller revelou uma diferença significante (p < 0,05) entre o grupo controle e os experimentais (I e II). Entretanto, apesar de o grupo II sofrer maior remineralização em relação ao grupo I, esta diferença não foi significante. Estes resultados sugerem que o uso da goma de mascar com sacarose e do dentifrício fluoretado pode ter efeito considerável na remineralização de lesões iniciais de cárie, tornando-se uma alternativa viável em sua prevenção.The aim of this study was to evaluate the remineralization of incipient carious lesions in bovine enamel in situ. Artificial carious lesions were produced and fixed in removable lower appliances in the region of the lingual surfaces of first molars, in six volunteers with ages between 18 and 22 years, who were subjected to 3 distinct experimental periods of 1 week each. In the first period (control group), patients brushed their teeth with a non-fluoridated dentifrice 4 times a day (after meals), and, in the second period (group I), patients used a dentifrice containing 1,500 ppm of fluorine (in the form of MFP). In the third period (group II) volunteers brushed their teeth with non-fluoridated dentifrice and used chewing gum containing 60% of sucrose during 20 minutes, 4 times a day (after meals). Before and after each treatment, the specimens underwent Vickers hardness test (200 g of load), and the remineralization percentage (alpha) was calculated. The control group showed 2.78% of demineralization, and groups I and II showed 3.36 and 5.21% of remineralization, respectively. Statistical analysis (with Kruskal-Wallis and Millers tests) showed significant difference (p < 0.05) between the control and experimental groups (I and II). Group II showed greater a than group I, but this difference was not significant. These results suggest that the use of sucrose-containing chewing gum and fluoridated dentifrice has a considerable effect on the remineralization of incipient carious lesions and may be a valuable alternative for their prevention

Biocompatibility of EDTA, EGTA and citric acid

This in vivo study evaluated, through the physicochemical assay method for quantification of enhanced vascular permeability, the irritating potential of EDTA, EGTA, citric acid and saline. Thirty-two male Wister rats were anesthetized and four experimental sites were demarcated on their backs. Injections of 2% Evans blue (20 mg/kg) were administered intravenously into the lateral caudal vein. The test solutions were immediately injected intradermally (0.01 mL) into the experimental sites. The animals were killed 30 min, 1, 3 and 6 h after injection of the solutions and each piece of skin was submerged in formamide and incubated at 45ºC for 72 h. After filtration, the optical density was measured in a spectrophotometer and the total amount of dye extracted from the samples was calculated by means of a standard calibration curve. Data were analyzed statistically by two-way ANOVA and Tukey's HSD test. Compared to control, EDTA had the greatest volume of dye followed by EGTA and citric acid, for all time periods. There were statistically significant differences between all solutions (p<0.01). Considering the periods assessed, a significant difference was observed between the 3- and 6-h groups (p<0.05), but not between the 30-min and 1-h groups. Among the organic acids evaluated in this study, citric acid yielded the lowest amount of extracted dye. This indicates that the citric acid was the least irritating solution

Tissue response to a membrane of demineralized bovine cortical bone implanted in the subcutaneous tissue of rats

The treatment of persistent bone defects has encouraged the search for proper techniques or bone substitutes. In Dentistry, a common problem in the treatment of periodontal bone defects is the growth of tissues within the lesion, such as the junctional epithelium, which impair regeneration of these tissues. Guided tissue regeneration (GTR), based on the separation of the tissues by means of membranes or barriers, was developed in an attempt to improve periodontal regeneration. The aim of this study was to histologically evaluate the tissue response to a membrane of demineralized bovine cortical bone implanted in the subcutaneous tissue of rats. The study periods were 1, 3, 7, 15, 30 and 60 days after implantation. Analysis of the histological sections demonstrated a moderate to intense inflammatory response at 1 and 3 days, moderate at 7 and 15 days, and almost absent at 30 and 60 days. Resorption of the membrane began 15 days after implantation, and at 60 days only remnants could be detected in some animals. We concluded that the demineralized bovine cortical bone membrane was well tolerated by the tissues and is completely resorbed after 30-60 days by mononuclear cells and multinucleated giant cells, which disappear upon completion of the process

Effect of absorbent tetracycline-loaded membrane used in the reduction of periodontal pockets: an in vivo study

This clinical study evaluated the influence of scaling and root planning (SRP), with and without the use of tetracycline-loaded bovine absorbent membrane, in the reduction of periodontal pockets according to 3 parameters: probing pocket depth (PPD), bleeding on probing (BOP) and plaque index (PI). Twenty-four patients were selected totalizing 144 random teeth divided in 2 groups (n=72 teeth) - control (SRP) and experimental (SRP with tetracycline-loaded absorbent membrane). PPD, BOP and PI were determined before and 28 days after the treatment. In all patients, the PPD values at the end of the treatment were always lower than the baseline values. There was a reduction of the PI for both treatments, but it was more evident on the experimental group. In conclusion, the use of tetracycline-loaded absorbent membrane could result in a better prognosis compared to scaling and root planning after only 28 days of evaluation

Inhibition Of Bovine Kidney Low Molecular Mass Phosphotyrosine Protein Phosphatase By Uric Acid.

Uric acid inhibited 50% of the activity of bovine kidney low molecular mass phosphotyrosine protein phosphatase at concentrations of 1.0, 0.4, 1.3, and 0.2 mM, respectively for p-nitrophenyl phosphate (p-NPP), flavine mononucleotide, beta-naphthyl phosphate and tyrosine phosphate (Tyr-P) as substrates. The mixed type inhibition of p-NPP hydrolysis was fully reversible, with Kic and Kiu values of 0.4 and 1.1 mM, respectively; the inhibition by uric acid shifted the pH optimum from 5.0 to 6.5. When Tyr-P was the substrate, competitive inhibition was observed with a Ki value of 0.05 mM. Inhibition studies by uric acid in the presence of thiol compounds, and preincubation studies in the presence of inorganic phosphate suggest that the interaction of uric acid with the enzyme occurred at the active site, but did not involve SH residues, and that the mechanism of inhibition depended on the structure of the substrates.17345-5

Effect Of Homologous Series Of N-alkyl Sulfates And N-alkyl Trimethylammonium Bromides On Low Molecular Mass Protein Tyrosine Phosphatase Activity.

The effect of anionic and cationic surfactants on acid phosphatase denaturation has been extensively studied. Low molecular mass (LMr) protein tyrosine phosphatase (PTP), a key regulatory enzyme involved in many different processes in the cell, was distinctly affected by anionic (homologous series of n-alkyl sulfates (C8-C14)) and cationic (n-alkyl trimethylammonium bromides (C12-C16)) surfactants. At concentrations 10-fold lower critical micellar concentration (cmc) values, the enzyme was completely inactivated in the presence of anionic surfactants, in a process independent of the pH, and dependent on the chain length of the surfactants. Under the same conditions, the effect of cationic surfactants on the enzyme activity was pH-dependent and only at pH 7.0 full inactivation was observed at concentrations 10-fold higher cmc values. In contrast to cationic surfactants the effect of anionic surfactants on the enzyme activity was irreversible and was not affected by the presence of NaCl. Inorganic phosphate, a known competitive inhibitor of PTP, protected the enzyme against inactivation by the surfactants. Our results suggest that the inactivation of the LMr PTP by anionic and cationic surfactants involved both electrostatic and hydrophobic interactions, and that the interactions enzyme-surfactants probably occurred at or near the active site.265133-4