Prescription of antibiotic prophylaxis in implant placement among Portuguese dentists: A web survey.

OBJECTIVES: This study aims to assess whether antibiotic prophylaxis for dental implant placement is commonly used by dentists in Portugal. MATERIALS AND METHODS: This cross-sectional survey study was based on a web survey with 22 questions divided into 5 parts. The 1st part focused on demographic details, work experience, and academic expertise, whereas the 2nd and 3rd parts were about the pre- and postoperative antibiotic prescriptions. The 4th and 5th parts focused on dentists' motivation for using/avoiding antibiotic prophylaxis and the use of a protocol, respectively. Data interpretation included descriptive analysis and statistical inference via cross-tabling with chi-square adjusted standardised for residual effects. RESULTS: Of the 204 valid surveys, at least one was received from every large Portuguese city which ensured the national coverage of the survey. Most respondents are not specialist dentists (72%). Sixty-four percent of the respondents always use antibiotic prophylaxis, while 29% adopt it only when grafting materials are employed. Most respondents use both pre- and postoperative regimens (55%). Amoxicillin 875 mg + clavulanic acid 125 mg is the most prescribed antibiotic (57%). Finally, the risk reduction of postoperative infection is the most frequent justification for the use of antibiotic prophylaxis (60%). CONCLUSIONS: The results highlight that most of the respondents do not follow the consensual international guidelines for prophylactic antibiotherapy in dental implant placement surgeries. This finding should serve as a rationale to increase the dissemination of those guidelines.

Injectability of calcium phosphate pastes: Effects of particle size and state of aggregation of ß-tricalcium phosphate powders.

The present study discloses a systematic study about the influence of some relevant experimental variables on injectability of calcium phosphate cements. Non-reactive and reactive pastes were prepared, based on tricalcium phosphate doped with 5 mol% (Sr-TCP) that was synthesised by co-precipitation. The varied experimental parameters included: (i) the heat treatment temperature within the range of 800-1100°C; (ii) different milling extents of calcined powders; (iii) the liquid-to-powder ratio (LPR); (iv) the use of powder blends with different particle sizes (PS) and particle size distributions (PSD); (v) the partial replacement of fine powders by large spherical dense granules prepared via freeze granulation method to simulate coarse individual particles. The aim was contributing to better understanding of the effects of PS, PSD, morphology and state of aggregation of the starting powders on injectability of pastes produced thereof. Powders heat treated at 800 and 1000°C with different morphologies but with similar apparent PSD curves obtained by milling/blending originated completely injectable reactive cement pastes at low LPR. This contrasted with non-reactive systems prepared thereof under the same conditions. Hypotheses were put forward to explain why the injectability results collected upon extruding non-reactive pastes cannot be directly transposed to reactive systems. The results obtained underline the interdependent roles of the different powder features and ionic strength in the liquid media on determining the flow and injectability behaviours.

The combination of infrared and microwave radiation to quantify trace elements in organic samples by ICP OES.

Sample-decomposition methods using microwave radiation in closed systems have been commonly used in the analysis of inorganic constituents; however, these methods are limited to small amounts of organic samples. This work proposes the combined use of infrared radiation and microwave radiation (IR-MW) to increase the amount of organic samples digested. The determination of Al, Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn in human-feed samples was accomplished by ICP OES. The results were in agreement with those obtained from conventional decomposition by microwave radiation (closed system). The results obtained using the proposed IR-MW system for standard reference material (whole milk powder, NIST 8435) were also compared. Agreements of 85-100% were obtained for Al, Ca, Cu, Fe, K, Mg, Na, P and Zn in the standard reference material. The IR-MW system is simple to implement and cheap because it uses commercially available infrared lamps and allows the use of infrared radiation in the microwave-digestion vessel. Additionally, it is possible to reach better precision in the analysis of the human-feed samples using the IR-MW system. The proposed method also allows total digestion of large sample amounts or samples rich in organic compounds can also be performed in the IR-MW system using small volumes of nitric acid.

Polymerisation of Kraft lignin from black liquors by laccase from Myceliophthora thermophila: effect of operational conditions and black liquor origin.

The capacity of laccase from Myceliophthora thermophila to promote the oxidative polymerisation of Kraft lignin (KL) was evaluated in several conditions of pH, temperature, enzyme dosage and treatment time. Moreover, different black liquors from the Kraft cooking of Eucalyptus globulus and mixture of Pinus pinaster/E. globulus were evaluated in order to determine the effect of the KL source on the polymerisation reaction. Furthermore, one of these black liquors was fractionated by sequential organic solvent fractionation and the polymerisation of the corresponding fractions was tested. Polymerisation products were analysed by size exclusion chromatography and Fourier transform infrared spectroscopy. The results provide evidence of notable lignin modifications after incubation with laccase. Structural oxidation and a notably molecular weight increase were attained, reaching a polymer of 69-fold its initial molecular weight depending on the raw lignin. Moreover, optimum values of reaction conditions were obtained: pH 7.3, 70°C, 2UmL(-1) and 2h.

Fuzzy logic model to describe anesthetic effect and muscular influence on EEG Cerebral State Index.

The well-known Cerebral State Index (CSI) quantifies depth of anesthesia and is traditionally modeled with Hill equation and propofol effect-site concentration (Ce). This work brings out two novelties: introduction of electromyogram (EMG) and use of fuzzy logic models with ANFIS optimized parameters. The data were collected from dogs (n=27) during routine surgery considering two propofol administration protocols: constant infusion (G1, n=14) and bolus (G2, n=13). The median modeling error of the fuzzy logic model with Ce and EMG was lower or similar than that of the Hill with Ce (p=0.012-G1, p=0.522-G2). Furthermore, there was no significant performance impact due to model structure alteration (p=0.288-G1, p=0.330-G2) and EMG introduction increased or maintained the performance (p=0.036-G1, p=0.798-G2). Therefore, the new model can achieve higher performance than Hill model, mostly due to EMG information and not due to changes in the model structure. In conclusion, the fuzzy models adequately describe CSI data with advantages over traditional Hill models.

Enzymatic polymerisation and effect of fractionation of dissolved lignin from Eucalyptus globulus Kraft liquor.

The potential ability of the laccase from Myceliophthora thermophila, either alone or with low molecular weight (LMW) additives, to polymerise a dissolved lignin from Kraft liquor of eucalypt cooking was investigated. A previous study of enzymatic performance (activity and stability) was carried out using a design experiment methodology. In addition, Kraft dissolved lignin (KDL) was fractionated according to two different protocols (solvent extraction and acidic fractionation) in order to identify possible lignin fractions with noticeable polymerisation ability. KDL and its corresponding lignin fractions were treated with laccase and analysed by size exclusion chromatography and Fourier transform infrared spectroscopy. The results provide conclusive evidence of notable lignin modifications after incubation with laccase. Moreover, lignin fractionation allows to obtain lignin fractions with different chemical characteristics and polymerisation capability. Depending on the type of raw lignin, molecular weight can increase from 4- to 21-fold by means of laccase polymerisation.

Differential effects of oral beta blockade on cardiovascular and sympathetic regulation.

In patients with hypertension, beta blockade decreases muscle sympathetic nerve activity (MSNA; micrographic technique) expressed in burst frequency (burst/min) but does not affect MSNA expressed in burst incidence (burst/100 heart beats), because reductions in blood pressure (BP) upon each diastole continue to deactivate the arterial baroreceptors, but at a slower heart rate (HR). We studied the effects of oral beta blockade on MSNA and baroreflex sensitivity (BRS) in normal participants. Bisoprolol (5 mg, 1 week) was administered in 10 healthy young adults, using a double-blind, placebo-controlled, randomized cross-over study design. The beat-to-beat mean RR interval (RR) and systolic blood pressure (SBP) series were analyzed by power spectral analysis and power computation over the very low frequency (VLF), low frequency, and high frequency (HF) bands. Baroreflex sensitivity was computed from SBP and RR cross-analysis, using time and frequency domain methods. Bisoprolol increased RR (P < .0005), decreased mean SBP and diastolic blood pressure values (P < .01), did not change the SBP and RR powers, except for RR power in VLF (P < .02) and SBP power in HF (P < .03). The MSNA variability (P > .13) and respiratory pattern (P = .84) did not change from placebo to bisoprolol condition. The bisoprolol-induced bradycardia was associated with higher burst/100 heart beats (P < .05) and bisoprolol did not affect burst/min (P = .80). Time domain BRS estimates were increased after bisoprolol (P < .05), while frequency domain ones did not change (P > .1). Oral bisoprolol induces differential effects on sympathetic burst frequency and incidence in normal participants. Peripheral sympathetic outflow over time is preserved as a result of an increased burst incidence, in the presence of a slower HR. Unchanged BP and HR and MSNA variability suggests that the larger burst incidence is not due to sympathetic activation.

Immunocytochemical study of gastrintestinal endocrine cells in insectivorous bats (Mammalia: Chiroptera).

The regional distribution and relative frequency of endocrine cells in the stomach and intestine of Phyllostomidae: Lonchorhina aurita and Molossidae: Molossus molossus bats were studied immunohistochemically. Three types of immunoreactive (IR) endocrine cells--to serotonin (5-HT), gastrin (GAS) and enteroglucagon (GLUC)--were found in the gastric mucosa and four types of IR cells were identified in the intestinal mucosa. This study showed an interespecfic difference in the regional distribution and relative frequency of endocrine cells in the Chiropteran alimentary tract.

Immunocytochemical study of gastrintestinal endocrine cells in insectivorous bats (Mammalia: Chiroptera) / Estudo imunocitoquímico das células endócrinas gastrintestinais de morcegos insetívoros (Mammalia: Chiroptera)

The regional distribution and relative frequency of endocrine cells in the stomach and intestine of Phyllostomidae: Lonchorhina aurita and Molossidae: Molossus molossus bats were studied immunohistochemically. Three types of immunoreactive (IR) endocrine cells - to serotonin (5-HT), gastrin (GAS) and enteroglucagon (GLUC) - were found in the gastric mucosa and four types of IR cells were identified in the intestinal mucosa. This study showed an interespecfic difference in the regional distribution and relative frequency of endocrine cells in the Chiropteran alimentary tract.

A distribuição regional e a freqüência relativa das células endócrinas no estômago e intestino dos morcegos insetívoros Phyllostomidae: Lonchorhina aurita e Mormoopidae: Molossus molossus foram estudadas pelo método de imunohistoquímica. Três tipos de células endócrinas imunorreativas (IR) à serotonina (5-HT), gastrina (GAS) e enteroglucagon (GLUC) foram localizadas na mucosa gástrica e quatro tipos de células endócrinas IR à 5-HT, GAS, colecistoquinina (CCK) e GLUC foram identificadas na mucosa intestinal. Este estudo mostrou uma diferença interespecífica na distribuição regional e na freqüência relativa das células endócrinas no trato alimentar de Chiropteros.

Electromigration of Mn, Fe, Cu and Zn with citric acid in contaminated clay.

Metal reactivity, speciation and solubility have an important influence in its transportation through a porous matrix by electrokinetics and, therefore, they dramatically affect the removal efficiency. This work deals with the effect of solubility and transport competition among several metals (Mn, Fe, Cu and Zn) during their transport through polluted clay. The unenhancement electrokinetic treatment results in a limited removal of the tested metals because they were retained into the kaolinite sample by the penetration of the alkaline front. Metals showed a removal degree in accordance with the solubility of the corresponding hydroxide and its formation pH. In 7 days of treatment, the removal results were: 75.6% of Mn; 68.5% of Zn, 40.6% of Cu and 14.8% of Fe. In order to avoid the negative effects of the basic front generated at the cathode, two different techniques were proposed and tested: the addition of citric acid as complexing agent to the polluted kaolinite sample and the use of citric acid to control de pH on the cathode chamber. Both techniques are based on the capability of citric acid to act as a complexing and neutralizing agent. Almost complete removal of Mn, Cu and Zn was achieved when citric acid was used (as neutralizing or complexing agent). But Fe only reached 33% of removal because it formed a negatively charged complex with citrate that retarded its transportation to the cathode.

Removal of organic pollutants and heavy metals in soils by electrokinetic remediation.

In this work, the feasibility of electrokinetic remediation for the restoration of polluted soil with organic and inorganic compounds had been development and evaluated using a model soil sample. The model soil was prepared with kaolinite clay artificially polluted in the laboratory with chromium and an azo dye: Reactive Black 5 (RB5). The electromigration of Cr in a spiked kaolinite sample was studied in alkaline conditions. Despite of the high pH registered in the kaolinite sample (around pH 9.5), Cr migrated towards the cathode and it was accumulated in the cathode chamber forming a white precipitate. The removal was not complete, and 23% of the initial Cr was retained into the kaolinite sample close to the cathode side. The azo dye RB5 could be effectively removed from kaolinite by electrokinetics and the complete cleanup of the kaolinite could be achieved in alkaline environment. In this condition, RB5 formed an anion that migrated towards the anode where it was accumulated and quickly degraded upon the electrode surface. The electrokinetic treatment of a kaolinite sample polluted with both Cr and RB5 yielded very good results. The removal of Cr was improved compared to the experiment where Cr was the only pollutant, and RB5 reached a removal as high as 95%. RB5 was removed by electromigration towards the anode, where the dye was degraded upon the surface of the electrode by electrochemical oxidation. Cr was transported towards the cathode by electromigration and electroosmosis. It is supposed that the interaction among RB5 and Cr into the kaolinite sample prevented premature precipitation and allow Cr to migrate and concentrate in the cathode chamber.

Remediation of phenanthrene from contaminated kaolinite by electroremediation-Fenton technology.

Polycyclic aromatic hydrocarbons (PAHs) cause a high environmental impact when released into the environment. The objective of this study was to evaluate the capacity to decontaminate polluted soils with phenanthrene as a model PAH using a combination of two technologies: electrokinetic remediation and Fenton process. Kaolinite was used as a model sample that was artificially polluted at the laboratory at an initial concentration of phenanthrene of 500 mg kg(-1) of dried kaolinite. The standard electrokinetic process resulted in negligible removal of phenanthrene from the kaolinite sample. Faster and more efficient degradation of this compound can be promoted by introduction of a strong oxidant into the soil such as hydroxyl radicals. For this reason, the Fenton reactions have been induced in several experiments in which H(2)O(2) (10%) was used as flushing solution, and kaolinite polluted with iron was used. When anode and cathode chambers were filled with H(2)O(2) (10%), the kaolinite pH is maintained at an acid value around 3.5 without pH control and an overall removal and destruction efficiency of phenanthrene of 99% was obtained in 14 days by applying a voltage gradient of 3 V cm(-1). Therefore, it is evident that a combined technology of electrokinetic remediation and Fenton reaction is capable of simultaneously removing and degrading of PAHs in polluted model samples with kaolinite.

Functional aspects of the tear film lipid layer.

The lipid layer is an essential component of the tear film, providing a smooth optical surface for the cornea and retarding evaporation from the eye. The meibomian lipids which compose it are well adapted for this purpose. They form a thin, smooth film whose thickness, and probably composition, influences the rate of evaporation. Their melting range ensures sufficient fluidity for delivery to the tear film from the lid margin reservoirs, while the film itself may exhibit a higher viscosity at the cooler temperature of the ocular surface. The factors governing lipid film formation during the blink are not fully understood, but one view is that the polar lipids, interacting with the aqueous sub-phase of the tear film, spread in advance of the non-polar components, which form the bulk of the film. The meibomian lipids stabilise the tear film by lowering its free energy; they carry water into the film during its formation and interact with lipid-binding proteins in the aqueous phase, such as tear lipocalin. The lipocalins, complexed with other tear components, may also contribute to the high, non-Newtonian viscosity of the tear film and its low surface tension, features which are essential for tear film stability. Formation of the lipid film is a complex process. Lipid is delivered to the tear film in the up-phase of the blink, more from the lower than the upper reservoir. The lipid layer comes to a stop well after completion of the blink and remains relatively immobile until it is compressed in the down-phase of the blink that follows. Then, it either retains its structure in a series of subsequent blinks, or is completely re-constituted after mixing with the reservoir lipids. Delivery of meibomian lipid to the marginal reservoirs is mainly the result of continuous secretion, under neural and hormonal control, supplemented by lid action. The reservoirs provide a hydrophobic barrier to tear overspill and to contamination by skin lipids which might destabilise the tear film. They probably also provide the chief route for meibomian lipid excretion.

Genomic comparisons and Shiga toxin production among Escherichia coli O157:H7 isolates from a day care center outbreak and sporadic cases in southeastern Wisconsin.

Contour-clamped homogeneous electric field pulsed-field gel electrophoresis (CHEF-PFGE) was used to compare Wisconsin isolates of Escherichia coli O157:H7, including 39 isolates from a 1994 day care center outbreak, 28 isolates from 18 individuals from the surrounding geographic area with sporadic cases occurring during the 3 months before the outbreak, and 3 isolates, collected in 1995, from patients with hemolytic-uremic syndrome (HUS) who were from eastern Wisconsin counties other than those inhabited by the day care center and sporadic-case individuals. The technique of CHEF-PFGE using XbaI identified seven highly related restriction endonuclease digestion profiles (REDPs) (93 to 98% similarity) among the 39 day care center isolates and nine XbaI REDPs (63 to 93% similarity) among the 28 isolates from sporadic-case individuals, including REDP 33, which was exhibited by both day care and sporadic-case isolates. PFGE analyses of sequential E. coli O157:H7 isolates from symptomatic day care center attendees revealed that the REDPs of 25 isolates from eight patients were indistinguishable whereas the REDPs of 2 of 6 isolates from two patients differed slightly (93 to 95% similarity). The REDPs of the three isolates from 1995 HUS patients were 78 to 83% similar, with REDP 26 being exhibited by one HUS-associated isolate and an isolate from one day care attendee who did not develop HUS. The genes for both Shiga toxins I and II (stx1 and stx2, respectively) were detected in all but one isolate (sporadic case), and Shiga toxin production by the day care center isolates was not significantly different from that of the other isolates, including the three HUS-associated isolates. Analyses of E. coli O157:H7 isolates from both the day care center outbreak and sporadic cases by CHEF-PFGE permitted us to define the REDP variability of an outbreak and geographic region and demonstrated that the day care center outbreak and a HUS case in 1995 were caused by E. coli O157:H7 strains endemic to eastern Wisconsin.

Nutritional homeostasis in locusts: is there a mechanism for increased energy expenditure during carbohydrate overfeeding?

Maintenance of carbohydrate balance via changes in CO2 output volume was investigated in locusts using a flow-through respirometer. The effect of an imbalance in the dietary protein to digestible carbohydrate ratio on expired CO2 levels was measured in locusts fed one of two synthetic diets [7% protein, 21% digestible carbohydrate (7:21) and 21% protein, 7% digestible carbohydrate (21:7)]. Additionally, the effect of dietary dilution was investigated by feeding locusts one of two diets with a close-to-optimal ratio of protein to carbohydrate, one containing 7% protein and 7% digestible carbohydrate (7:7) and the other containing 21% protein and 21% digestible carbohydrate (21:21). For insects fed unbalanced diets, a higher CO2 output volume was measured during feeding on diet 7:21 when compared with insects fed on diet 21:7. Locusts also expired a greater volume of CO2 during the entire 2h observation period. This response is consistent with specific metabolic control of carbohydrate balance via enhanced respiration. For insects fed balanced diets, the total volume of CO2 expired over the duration of a meal was greater for insects fed diet 7:7 than for those fed diet 21:21, although this was due entirely to meals lasting longer on the more dilute diet. However, the basal level of respiration rate was greater for insects fed diet 21:21 and, as a result, over the entire 2h period, CO2 output volume did not differ between locusts fed diet 7:7 or 21:21. A possible mechanism for enhanced CO2 output volume on the nutritionally unbalanced diet was investigated, namely triglyceride/fatty-acid substrate cycling. There was no evidence for the presence of the thermogenic effect of this particular cycle on locusts as a means for dealing with excess ingested carbohydrate.