Avaliação da resistência adesiva e características da zircônia após diferentes tratamentos de superfície / Bond strength and surface characteristics evaluation of zirconia after different treatments

O objetivo desse estudo in vitro foi avaliar a resistência adesiva, rugosidade superficial, ângulo de contato e o espectro infravermelho da zircônia, após diferentes tratamentos de superfície. Para isso, blocos (n=9) de zircônia Y-TZP (e.max ZirCad - Ivoclar, Schann, Liechtenstein) foram seccionados em 39 fatias (12 x 11x 3 mm) divididas em grupos de acordo com cada teste. Para resistência adesiva, 20 fatias foram divididos em: 2 grupos controle; JAT, jateamento com óxido de alumínio e sílica + primer (Monobond Plus - Ivoclar, Schann, Liechtenstein); HFP, condicionamento com ácido fluorídrico 10% + primer, e 3 experimentais: PL, plasma (Plasma Não Térmico de Superfície - modelo SAP); PLP, plasma + primer; HFPLP, ácido fluorídrico + plasma + primer. Cada fatia de zircônia foi cimentada (Multilink N - Ivoclair, Schann, Liechtenstein) a um bloco pré-polimerizado de resina composta. Após a cimentação os espécimes foram seccionados, e 48 palitos com área adesiva de 1 mm2 foram obtidos em cada grupo para o ensaio de microtração (µTBS). Quatro outras fatias foram submetidas à análise de rugosidade superficial e 12 fatias submetidas à análise do ângulo de contato, após os seguintes tratamentos de superfície: sem tratamento (AV), aplicação de ácido fluorídrico a 10% (AHF), aplicação de plasma (AP) e jateamento (AJ), sendo que para o ângulo de contato foram feitas medições imediatamente após o tratamento, após 12 e 24 horas. Os resultados foram submetidos à análise estatística Anova e teste de Tukey a 5% (p< 0,05). Os espectros das ligações químicas da superfície da zircônia foram determinados em 3 outras amostras após as seguintes condições: sem tratamento (AV), jateamento (JAT) e aplicação de ácido fluorídrico 10% seguido da aplicação do plasma (AHFP). Em termos de adesão, não houve diferença estatística significante entre os grupos JAT e HFPLP, porém esses 2 foram estatisticamente superiores ao grupos HFP, PL e PLP. O jateamento demonstrou aumentar significantemente a rugosidade superficial em relação aos demais grupos. O plasma demonstrou diminuir o ângulo de contato da superfície da zircônia imediatamente e ao longo de 48 horas(AU)

The purpose of this in vito study was to evaluate zirconia bond strength, surface roughness, contact angle and to mesure infrared spectrum after different surface treatments. Y-TZP zirconium (e.max ZirCAD - Ivoclair, Schann, Liechtenstein) blocks (n=9) were sliced into 36 discs (12 x 11 x 3 mm) and divided (n=4) into surface treatment groups as following: two control groups: JAT, airborneparticle abrasion and HFP, 10% hydrofluoric acid etching + primer (Monobond Plus - Ivoclair, Schann, Liechtenstein)application ,and three experimental groups: PL, non-thermal plasma (Surface Non-Thermal Plasma SAP model) application; PLP non-thermal plasma + primer application, and HFPLP, 10% hydrofluoric acid etching + non-thermal plasma + primer application. Each zirconia disk was cemented (Multilink N - Ivoclair, Schann, Liechtenstein) to a pre-polymerized resin block (Filtek Z350 - 3M, St Paul, MN, USA). After cementation the specimens were sectioned and 48 sticks with adhesive area of 1 mm2 obtained from each group for micro-tensile testing (µTBS). Four discs were submitted to surface roughness analysis and 12 discs to contact angle analysis, after the following surface treatments: no treatment (AV), 10% hydrofluoric acid etching (AHF), non-thermal plasma application (AP); and airborne- particle abrasion (AJ). The results were submitted to ANOVA and Tukey's test (p < 0.05). Zirconia surface chemical bonds spectrum was determined in infrared spectroscopy for three specimens after the conditions: no treatment; airborne- particle abrasion and hydrofluoric acid etching + non-thermal plasma application. The results showed no statistically significant differences between the groups JAT and HFPLP, but these two groups were statistically superior to HFP, PL and PLP. Airborne- particle abrasion resulted in a significant increase of surface roughness compared to the other groups. Non-thermal plasma was shown to decrease the contact angle of the surface, within 48 hours(AU)

A modified infrared spectrometer with high time resolution and its application for investigating fast conformational changes of the GTPase Ras.

Time-resolved infrared spectroscopy is a valuable tool for the investigation of proteins and protein interactions. The investigation of many biological processes is possible by means of caged compounds, which set free biologically active substances upon light activation. Some caged compounds could provide sub-nanosecond time resolution, e.g., para-hydroxyphenacyl-guanosine 5'-triphosphate (GTP) forms GTP in picoseconds. However, the time resolution in single shot experiments with rapid-scan Fourier transform infrared (FT-IR) spectrometers is limited to about 10 ms. Here we use an infrared diode laser instead of the conventional globar and achieve a time resolution of 100 ns. This allows for the time-resolved measurement of the fast Ras(off) to Ras(on) conformational change at room temperature. We quantified the activation parameters for this reaction and found that the free energy of activation for this reaction is mainly enthalpic. Investigation of the same reaction in the presence of the Ras binding domain of the effector Raf (RafRBD) reveals a four orders of magnitude faster reaction, indicating that Ras·RafRBD complex formation directly induces the conformational change. Recent developments of broadly tunable quantum cascade lasers will further improve time resolution and usability of the setup. The reported 100 ns time resolution is the best achieved for a non-repetitive experiment so far.

Infrared spectroscopic studies of cells and tissues: triple helix proteins as a potential biomarker for tumors.

In this work, the infrared (IR) spectra of living neural cells in suspension, native brain tissue, and native brain tumor tissue were investigated. Methods were developed to overcome the strong IR signal of liquid water so that the signal from the cellular biochemicals could be seen. Measurements could be performed during surgeries, within minutes after resection. Comparison between normal tissue, different cell lineages in suspension, and tumors allowed preliminary assignments of IR bands to be made. The most dramatic difference between tissues and cells was found to be in weaker IR absorbances usually assigned to the triple helix of collagens. Triple helix domains are common in larger structural proteins, and are typically found in the extracellular matrix (ECM) of tissues. An algorithm to correct offsets and calculate the band heights and positions of these bands was developed, so the variance between identical measurements could be assessed. The initial results indicate the triple helix signal is surprisingly consistent between different individuals, and is altered in tumor tissues. Taken together, these preliminary investigations indicate this triple helix signal may be a reliable biomarker for a tumor-like microenvironment. Thus, this signal has potential to aid in the intra-operational delineation of brain tumor borders.

Infrared spectral imaging as a novel approach for histopathological recognition in colon cancer diagnosis.

Innovative diagnostic methods are the need of the hour that could complement conventional histopathology for cancer diagnosis. In this perspective, we propose a new concept based on spectral histopathology, using IR spectral micro-imaging, directly applied to paraffinized colon tissue array stabilized in an agarose matrix without any chemical pre-treatment. In order to correct spectral interferences from paraffin and agarose, a mathematical procedure is implemented. The corrected spectral images are then processed by a multivariate clustering method to automatically recover, on the basis of their intrinsic molecular composition, the main histological classes of the normal and the tumoral colon tissue. The spectral signatures from different histological classes of the colonic tissues are analyzed using statistical methods (Kruskal-Wallis test and principal component analysis) to identify the most discriminant IR features. These features allow characterizing some of the biomolecular alterations associated with malignancy. Thus, via a single analysis, in a label-free and nondestructive manner, main changes associated with nucleotide, carbohydrates, and collagen features can be identified simultaneously between the compared normal and the cancerous tissues. The present study demonstrates the potential of IR spectral imaging as a complementary modern tool, to conventional histopathology, for an objective cancer diagnosis directly from paraffin-embedded tissue arrays.

[Nondestructive identification of different oil content maize kernels by near-infrared spectra].

Using 220 maize single kernels, containing 75 common maize single kernels, 72 high-oil maize single kernels and 73 super high-oil maize single kernels as study materials, BPANN identification model was set up for maize single kernel with different oil content based on principal components of near infrared (NIR) spectra. Four fifths of the samples were randomly selected as training set and the other samples as prediction set. Fourteen principal components from the second to the fifteenth were selected as nets input and -1, 0, 1 as nets output. Ten models were set up like this and the accurate identification rate of all the training sets can reach 100%. For prediction sets, fifteen common corn grain samples had an average accurate identification rate of 99.33%, fourteen high-oil corn grain samples had an average accurate identification rate of 97.88%, fourteen super high-oil corn grain samples had an average accurate identification rate of 91.43%, and total maize grains in prediction set had an average accurate identification rate of over 95%. Results showed that NIR spectroscopy combined with BP-ANN technology could identify maize kernels fast and nondestructively according to oil content, which offered a very useful classification method for maize seed breeding. The effect of different principal component on BPANN models was also studied. Results told us that the first principal component with over 99% of variance contribution had negative effect on the identification model. The predictive ability of identification models set up by different principal component was discriminatory, although the learning accurate identification rates were all 100%. So it is necessary to choose correlative principal component to set up identification model.

Spectral detection of micro-metastases in lymph node histo-pathology.

The first detection of breast cancer micrometastases in lymph nodes by infrared spectral imaging and methods of multivariate analysis is reported. Micrometastases are indicators of early spread of cancer from the organ originally affected by disease, and their detection is of prime importance for the staging and treatment of cancer. Infrared spectral imaging, at a spatial resolution of ca. 10-12 mum, can detect small metastases down to the level of a few cancerous cells. The results presented here add to a rapidly growing database of infrared spectral imaging results for cancer diagnostics.

Felbamate urolithiasis.

PURPOSE: To report a case of felbamate (FBM) urolithiasis. METHODS: Urographic imaging [sonography, abdominal computed tomography (CT), intravenous pyelogram, voiding cystourethrogram] and urologic procedures (cystoscopy with lithotripsy, ureteral stent) to define and capture the stones. Stone identification was by infrared spectroscopy and gas chromatography/mass spectrometry. RESULTS: A 15-year-old boy had painful hematuria, bilateral ureteral obstruction, and urinary retention. Kidney, bladder, and ureteral stones were found, and ureteral stent placement was required to relieve obstruction. The stone material was identified as FBM by chemical analysis. Stone formation ceased with discontinuation of FBM. CONCLUSIONS: FBM urolithiasis can occur, and possible contributory factors include high felbamate dosage, drug polypharmacy, and risk factors for forming stones of other types. FBM urolithiasis may be heralded by crystalluria.

[The state of the dental hard tissues in persons under the influence of ionizing radiation (based on the data from infrared spectroscopy)]. / Stan tverdykh tkanyn zubiv u osib, iaki zaznaly vplyvu ionizuiuchoho vyprominiuvannia (za danymy infrachervonoï spektroskopiï).

A total of 27 teeth were examined in those subjects having been exposed to ionizing radiation in doses between 0.5 and 2.0 Gy, together with ten teeth of essentially healthy individuals. The enamel, dentine and cement mineral and protein contents were studied versus control with the aid of infrared spectroscopy techniques. It has been ascertained that in the teeth of patients presenting with dose loads there take place changes in the organic matrix. Amide I: amide II ratio tends to diminish toward contribution of Amide I. The mineral composition of the enamel reveals practically no changes under exposure to radiation. The dentine and cement display clear-cut changes in the mineral component. There appear absorption bands that belong to more soluble forms of calcium phosphate, which fact suggests an active destructive process in underlying hard tissues of the teeth, that gets intensified under exposure to ionizing radiation.

[The technology for manufacturing antiparasitic preparations. 9. The new preparation tizanox and an evaluation of its anti-Hymenolepis activity]. / Tekhnologiia proizvodstva protivoparazitarnykh preparatov. 9. Novyi preparat tizanoks i otsenka ego protivogimenolepidoznoi aktivnosti.

The paper describes a procedure for manufacturing the new anthelminthic Tizanox. It shows it necessary to administer a larger dose of the drug than that of azinox (praziquantel) to treat experimental hymenolepiasis. However, the lower toxicity of Tizanox enhances its chemotherapeutical index.

A modified rebreathing technique using an infrared gas analyzer.

To lower the cost and improve accessibility of the rebreathing technique for measuring cardiopulmonary function during exercise, we implemented a fast-response infrared (IR) gas-analyzer system to simultaneously measure lung diffusing capacity, cardiac output lung tissue volume, and lung volume by a rebreathing technique in five healthy subjects at rest and during steady-state exercise. Interferences by water vapor and CO2 on the analyzer were determined and corrected for. During rebreathing, a gas mixture of 0.4% C2H2-0.3% CH4-9% He-30% O2, and either 0.3% C18O or 0.3% C16O in a balance of N2 was simultaneously sampled by both a mass spectrometer and the IR analyzer, permitting paired comparisons. Measurements obtained by the two devices were not significantly different. We conclude that this modified rebreathing technique using the IR analyzer is accurate for the measurement of cardiopulmonary function at rest and during exercise.

Neutrophil activation in jugular venous blood during carotid endarterectomy.

OBJECTIVES: Neutrophils may play an important role in cerebral ischaemia. We investigated whether neutrophil activation can be detected in cerebral venous blood during the mild cerebral hypoxia and reperfusion that occurs during carotid cross clamping and declamping for endarterectomy. DESIGN, SETTING AND MATERIALS: The ipsilateral jugular bulb was cannulated at operation in 16 patients undergoing carotid endarterectomy. Blood was taken immediately prior to and 30 seconds following internal carotid cross clamping; then immediately prior to, 30 s and 2 m following declamping. Blood was also taken from a peripheral vein in the foot. Intracerebral oxygen saturation (CsO2) was measured continuously by near infrared cerebral spectroscopy. Neutrophil activation was measured by flow cytometric detection of fluorescence to hydrogen peroxide in unstimulated cells and phorbol myristate acetate stimulated cells, and expressed as mean fluorescent intensity (MFI). OUTCOME MEASURES: Neutrophil activation and cerebral oxygenation. MAIN RESULTS: CsO2 fell from 68% (95% Confidence interval 64%-72%) to 63% (59%-68%) following carotid cross clamping (p < 0.05, repeated measures analysis of variance). This recovered slightly during the cross clamp period to 64% but only returned to preclamp levels following declamping (p > 0.05). Neutrophil hydrogen peroxide generation by stimulated neutrophils rose significantly from 0.79 mean fluorescent intensity (0.53-1.19) to 1.46 (0.98-2.20) but no there was no further rise following cross clamp release. There was no significant neutrophil activation in the peripheral samples. CONCLUSIONS: These results indicate that even mild cerebral hypoxia is associated with priming of neutrophils in cerebral venous blood.

Calcium carbonate in cholesterol gallstones: polymorphism, distribution, and hypotheses about pathogenesis.

This study of sets of cholesterol gallstones collected consecutively from 222 patients in La Paz, Bolivia, and Mexico City, Mexico, has developed a reliable infrared (IR) spectroscopic method for the detection of calcium carbonate in cholesterol gallstones and provided the basis for simultaneous identification of each of its three polymorphs: calcite, vaterite, and aragonite. The peaks in the 854 to 876 cm-1 region demonstrated 98% sensitivity and specificity for carbonate detection. As little as 3% carbonate by weight could be detected using these peaks. The overall incidence of carbonate was 19% in these populations containing a high proportion of Amerinds. Infrared microspectroscopy of 10 to 50 microns particles, dissected from stones, allowed a ring-by-ring examination of 11 carbonate-containing stones. It was determined that different carbonate polymorphs, when present in the same gallstone, almost always occurred in separate rings. In approximately half of the gallstones, different polymorphs were present in successive layers in the same stone, indicating that conditions governing stone growth changed cyclically. Carbonates were usually precipitated in peripheral layers rather than in the center, supporting the theory that formation of calcium carbonates may be related to episodes of intermittent obstruction of the cystic duct, as opposed to being a major factor in stone nidation.