Effect of xylitol varnishes on remineralization of artificial enamel caries lesions in situ.

OBJECTIVES: Analyze the effect of varnishes containing xylitol compared to commercial fluoridated varnishes on the remineralization of artificial enamel caries lesions in situ. METHODS: Twenty subjects took part in this crossover, double-blind study performed in four phases of 5days each. Each subject worn palatal appliances containing four predemineralized bovine enamel specimens. Artificial caries lesions were produced by immersion in 30ml of lactic acid buffer containing 3mM CaCl2·2H2O, 3mM KH2PO4, 6µM tetraetil metil diphosphanate (pH 5.0) for 6days. The specimens in each subject were treated once with the following varnishes: 20% xylitol (experimental); Duofluorid™ (6% NaF, 6% CaF2), Duraphat™ (5% NaF, positive control) and placebo (no-F/xylitol, negative control). The varnishes were applied in a thin layer and removed after 6h. Fifteen subjects were able to finish all phases. The enamel alterations were quantified by surface hardness and transversal microradiography. The percentage of surface hardness recovery (%SHR), the integrated mineral loss and lesion depth were statistically analyzed by Friedmann and Dunn's tests test (p<0.05). RESULTS: Enamel surface remineralization was significantly increased by Duraphat™, Duofluorid™ and 20% xylitol formulations. Significant subsurface mineral remineralization could also be seen for the experimental and commercial varnishes, except for Duraphat™, when the parameter "lesion depth" was considered. CONCLUSIONS: 20% xylitol varnish seem to be a promising alternative to increase surface and subsurface remineralization of artificial caries lesions in situ. CLINICAL SIGNIFICANCE: effective vehicles are desirable for caries control. Xylitol varnishes seem to be promising alternatives to increase enamel remineralization in situ, which should be confirmed by clinical studies.

Maximum number of repetitions, total weight lifted and neuromuscular fatigue in individuals with different training backgrounds.

The aim of this study was to evaluate the performance, as well as neuromuscular activity, in a strength task in subjects with different training backgrounds. Participants (n = 26) were divided into three groups according to their training backgrounds (aerobic, strength or mixed) and submitted to three sessions: (1) determination of the maximum oxygen uptake during the incremental treadmill test to exhaustion and familiarization of the evaluation of maximum strength (1RM) for the half squat; (2) 1RM determination; and (3) strength exercise, four sets at 80% of the 1RM, in which the maximum number of repetitions (MNR), the total weight lifted (TWL), the root mean square (RMS) and median frequency (MF) of the electromyographic (EMG) activity for the second and last repetition were computed. There was an effect of group for MNR, with the aerobic group performing a higher MNR compared to the strength group (P = 0.045), and an effect on MF with a higher value in the second repetition than in the last repetition (P = 0.016). These results demonstrated that individuals with better aerobic fitness were more fatigue resistant than strength trained individuals. The absence of differences in EMG signals indicates that individuals with different training backgrounds have a similar pattern of motor unit recruitment during a resistance exercise performed until failure, and that the greater capacity to perform the MNR probably can be explained by peripheral adaptations.

Inhibition of acetylcholinesterase from Electrophorus electricus (L.) by tricyclic antidepressants.

The effects of tricyclic antidepressants drugs (TCA) amitriptyline, imipramine and nortriptyline, on purified Electrophorus electricus (L.) acetylcholinesterase (AChE; acetylcholine hydrolase, EC 3.1.1.7) were studied using kinetic methods and specific fluorescent probe propidium. The antidepressants inhibited AChE activity by a non-competitive mechanism. Inhibition constants range from 200 to 400 microM. Dimethylated amitriptyline and imipramine were more potent inhibitors than the monomethylated nortriptyline. Fluorescence measurements using bis-quaternary ligand propidium were used to monitor ligand-binding properties of these cationic antidepressants to the AChE peripheral anionic site (PAS). This ligand exhibited an eight-fold fluorescence enhancement upon binding to the peripheral anionic site of AChE from E. electricus (L.) with K(D)=7 x 10(-7)M. It was observed that TCA drugs displaced propidium from the enzyme. On the basis of the displacement experiments antidepressant dissociation constants were determined. Similar values for the inhibition constants suggest that these drugs have similar affinity to the peripheral anionic site. The results also indicate that the catalytic active center of AChE does not participate in the interaction of enzyme with tricyclic antidepressants. These studies suggest that the binding site for tricyclic antidepressants is located at the peripheral anionic site of E. electricus (L.) acetylcholinesterase.

Purification and partial characterization of creatine kinase from electric organ of Electrophorus electricus (L.).

The present investigation deals with the purification and the partial characterization of the soluble creatine kinase (CK) isoenzyme, isolated from the electric organ electrocyte of Electrophorus electricus (L.). Purification was performed by precipitation of the enzyme in the crude extract with ammonium sulfate (80%). The precipitate obtained was analyzed on an ion exchange column of diethylaminoethyl cellulose-52 (DEAE) followed by gel filtration on Superose 12 in a Fast Protein Liquid Chromatography (FPLC) system. Electrophoretic mobility of the active peak confirmed previous results identifying the hybrid isoenzyme MB in the electrocyte cytoplasm. Electrocyte CK is a dimeric enzyme with two identical subunits of approximately 40 kDa as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The sequence analysis of the N-terminal peptide (14 amino acids) of the 40 kDa subunit showed homology with other CK enzymes from electric fish (Torpedo) and human muscle type CK.

[Fonsecaea pedrosoi-caused chromoblastomycosis in the state of Maranhão. I. The clinical, epidemiological and evolutionary aspects]. / Cromoblastomicose produzida por Fonsecaea pedrosoi no Estado do Maranhão. I--Aspectos clínicos, epidemiologicos e evolutivos.

The aim of this study was to observe the clinical and of epidemiological behavior of chromoblastomycosis in the State of Maranhão. A retrospective and prospective study of 13 cases was performed at the infectious diseases section of the Hospital dos Servidores do Estado do Maranhão, from November, 1988 to July, 1991. In the investigation a protocol record was used with a view to further analysis. A higher prevalence between 50 and 60 years of age (46.1%) and in male patients (92.3%) was noted. Twelve patients (92.3%) were from Maranhão State, and 10 of them (76.9%) came from the western microregion of the State of Maranhão. Regarding occupation, 92.3% were land workers, and most of them presented the lesions on the lower limbs (84.6%) of a vegetant warty aspect, brown in color with itching. Histopathological examination diagnosed chromomycosis in 100% of the cases. Culture was performed in 11 cases, and Fonsecaea pedrosoi isolated in 9 of them. Treatment with 5-fluorocytosine resulted in a good evolutive response. This study indicates the existence of a probable endemic area of chromomycosis in hinterland of Maranhão (western microregion) that hither to unknown.

[Spontaneous healing of leishmaniasis caused by Leishmania viannia braziliensis in cutaneous lesions]. / Cura espontânea da leishmaniose causada por Leishmania viannia braziliensis em lesões cutâneas.

In field clinics in the communities of Três Braços and Corte de Pedra, Bahia, we have attended 1.416 patients with tegumentary leishmaniasis in fourteen years, the predominant species in transmission is Leishmania Viannia brasi liensis (LVB). Because of the danger of metastasis with this infection treatment was routinely recommended with Glucan-time. However sixteen patients refused injection therapy and six women were pregnant when seen and not treated. All patients were followed up in our clinic. All these patients closed their skin ulcers although one subsequently relapsed. Patients were followed up for variable periods (four to twelve years), after the diagnosis. In nine patients (40.9%) of the cohort, the time to healing after initiation of the lesion was calculated as six months of evolution. At twelve months, nineteen patients (86.3%) had complete healing of their lesions. In three patients an active lesion was present for longer than one year. The determinants of this variable natural evolution of human LVB lesion remains completely unknown. It is difficult for us to understand and compare the effects of therapeutic agents in mucocutaneous leishmaniasis.