Orientador: Léa Assed Bezerra da Silva / Banca: Mario Roberto Leonardo / Banca: Mário Tanomaru Filho / Banca: Clóvis Monteiro Bramante / Banca: José Antônio Poli de Figueiredo / Resumo: O objetivo deste trabalho foi avaliar a liberação de íons cálcio e pH, de três pastas à base de hidróxido de cálcio, a saber: UltraCal- XS, Calcicur e pasta aquosa, além de avaliar a resposta tecidual das mesmas em tecido conjuntivo subcutâneo, do dorso de ratos Wistar, nos períodos de 7 e 30 dias. A análise do cálcio contido nas pastas testadas foi realizada utilizando a espectrofotometria por absorção atômica. As leituras de pH foram efetuadas com o emprego de um peagâmetro. As mensurações do pH e liberação de cálcio foram realizadas nos períodos experimentais de 1 hora, 1, 2, 3, 7, 15, 30, 45 e 60 dias. Para a resposta de biocompatibilidade foram empregados 18 ratos Wistar, nos quais foram inseridos, no tecido subcutâneo do dorso, 04 tubos de polietieleno, contendo em cada tubo uma das 3 pastas, nos períodos de 7 e 30 dias. Os resultados indicaram diferenças significativas entre o pH e liberação de cálcio das pastas estudadas, quando foram levados em consideração os valores no período inicial, valores mínimo, máximo e quando da comparação dos valores final e inicial (delta). O pH e liberação de cálcio foram maiores para a pasta controle e Calcicur, respectivamente, quando comparadas a UltraCal (ANOVA-1via). No experimento de biocompatibilidade não foi possível observar diferenças estatísticas significantes entre os 3 materiais testados nos períodos de 7 e de 30 dias, entretanto, levando em consideração os eventos celulares, foi possível identificar que, para as 3 pastas de hidróxido de cálcio, ocorreu uma redução nos escores de avaliação de 7 para 30 dias (ANOVA-2 vias). As pastas UltraCal, Calcicur e controle mantiveram-se com pH acima de 12 em todos tempos testados. A dissociação em íons cálcio e hidroxila, das pastas controle e Calcicur, aconteceu de forma mais rápida, até 45 dias, em função do veículo aquoso. As 3 pastas... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: The aim of this study was to evaluate the release of calcium íons and pH of three calcium hydroxide pastes: UltraCal XS, Calcicur and aqueous paste besides evaluating the tissue's response in subcutaneous conjunctive tissue extracted from the dorsal part of Wistar rats in the period of 7 and 30 days. The analysis of the calcium present in the pastes was performed using a spectrophotometer by atomic absorption. A pHmeter was employed to read the measured pH. The pH and calcium release measurements were performed in the experimental times of 1 hour and 1, 2, 3, 7, 15, 30, 45 and 60 days. For the biocompatibility response 18 Wistar rats were used, on which were inserted into the dorsal subcutaneous tissue poliethylene tubes containing each one the three pastes, in the periods of 7 and 30 days. The results showed significant differences between the pH and calcium release of the pastes considering the values from starting time, minimum and maximum values, and when comparing the final and starting values (delta). The results showed higher pH and calcium release to the control paste and Calcicur respectively when compared to UltraCal (ANOVA- one way). On the biocompatibility experiment, statistically significant differences were not observed among the three tested materials in the periods of 7 and 30 days. Nevertheless, considering the cellular events, it was possible to identify that for all three calcium hydroxide pastes there was an evaluation score reduction from 7 to 30 days (ANOVA-two ways). Ultracal, Calcicur and the control paste maintained the pH above 12 during all times. The calcium and hydroxil ions from the control paste and Calcicur presented a faster ionic dissociation, up to 45 days due to the aqueous vehicle. The biocompatibility of the three pastes was observed in the evaluated observation times. / Doutor

Calcium phosphate compounds have been widely utilised in the interdisciplinary field of biomaterials research and are used clinically in a number of medical devices. In the present work, calcium phosphate compositions were prepared by two precipitation methods: a classic aqueous precipitation method and a novel biomimetic precipitation method. The aqueous precipitation method was used to produce a range of hydroxyapatite and carbonate-substituted hydroxyapatite compositions that would act as reference materials, but more importantly to allow a method of determining the Ca/P molar ratio of these compositions using X-ray diffraction data. The importance of this was that a simple technique would be required for studying the calcium phosphates produced later by biomimetic methods, as the very low yields prevents traditional methods such as XRF. It was found that Rietveld refinement of XRD data from precipitated apatites that had been heated at between 800 and 1200°C in air provided quantitative phase compositions that could then be used to calculate Ca/P molar ratios. In order to use synthesis conditions that were more similar to in vivo mineralisation, calcium phosphate compositions were directly prepared by using alkali-induced 'biomimetic' precipitation from Simulated Body Fluid (SBF) under controlled conditions. The key parameters that were studied were the effect of precipitation pH, the SBF concentration, the reaction time, the soaking time, and the magnesium and the carbonate ion concentration of the SBF solution. The key finding was that while the precipitated product obtained from 'conventional' SBF was an amorphous calcium phosphate with a Ca/P molar ratio of 1.5, irrespective of the pH, SBF concentration, reaction time or carbonate ion concentration, the gradual removal of magnesium ions from the SBF solution led to the precipitation of firstly a Ca-deficient apatite and eventually (for low Mg concentrations and a Mg-free SBF) a stoichiometric hydroxyapatite with a Ca/P molar ratio of 1.67. This method resulted in very low yields, typically (50 mg from 100 ml of SBF) but control of parameters could yield different phase compositions and could also affect the crystal size and the crystallinity of the product. These observations highlighting the important role of magnesium ions in the SBF on the composition of the calcium phosphate phase that would precipitate raised the question of what effect does SBF magnesium ion content have on the surface apatite precipitation on various biomaterials when incubated in SBF, which is the classic in vitro bioactivity test. Studies that incubated bioactive glass discs and powder (45S5 composition) and dense hydroxyapatite ceramic discs in conventional SBF and an Mg-free SBF showed that the rate of surface apatite precipitation was significantly affected by the Mg content in the SBF. For the case of bioactive glass discs, a surface apatite layer formed in 2 hours when incubated in an Mg-free SBF compared to 24 hours in conventional SBF.

Orientador: Adil Muhib Samara / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-12T15:20:38Z (GMT). No. of bitstreams: 1 Mardegan_LucianaCalvo_M.pdf: 1133557 bytes, checksum: 3724bd20274a4ec0c0d6a02b0da7547d (MD5) Previous issue date: 2008 / Resumo: No Brasil, a prevalência da osteoartrite é de cerca de 16,2%, sendo que aos 75 anos, 85% das pessoas apresentarão evidências clínica ou radiológica da doença. A condrocalcinose é a segunda principal causa de doença por deposição de cristais. Estudos recentes têm demonstrado uma prevalência de 8-10% de condrocalcinose radiológica em pacientes com 60 anos ou mais. Nosso objetivo é avaliar a influência dos cristais de pirofosfato de cálcio na osteoartrite inflamatória de joelhos. Foram avaliados vinte pacientes do Ambulatório de Ortopedia do Hospital de Clínicas da Unicamp, com critérios diagnóstico de osteoartrite em joelhos. Realizaram-se exames de imagem (radiografia, tomografia computadorizada e ressonância nuclear magnética), colheita do líquido sinovial com posterior análise por microscopia de luz compensada e polarizada, além da dosagem de cálcio no dia da colheita e noventa e seis horas após. Os achados foram correlacionados com a presença ou não de osteoartrite inflamatória. Entre os vinte pacientes estudados, onze apresentavam osteoartrite inflamatória, sendo que a condrocalcinose foi evidenciada na radiografia, tomografia e na ressonância de um paciente e apenas na tomografia de outro. Entre os nove que não apresentavam osteoartrite inflamatória, apenas um apresentou imagem de condrocalcinose na tomografia. Foi dosado o cálcio no LS de quinze pacientes, sendo que não houve diferença significativa entre a média do cálcio 1 e cálcio 2. Não foi possível estabelecer a relação entre a presença de cristais de pirofosfato de cálcio e a osteoartrite inflamatória de joelhos / Abstract: Objective: Osteoarthritis prevalence in Brazil is around 16, 2%, and, by the age of 75, 85% of the individuals will present with clinical or radiological signs of the disease. Chondrocalcinosis is the second cause of crystal deposition pathology. Recent studies show 8-10% of radiologic evidence of chondrocalcinosis in people older than 60 years. Our goal is to evaluate the impact of calcium pyrophosphate crystals on inflammatory knee osteoarthritis. Methods: Twenty patients from UNICAMP Clinical Hospital, Orthopedic clinic, with complains of knee joint pain were assessed. Image exams (Radiography, TC scan and Magnetic Resonance Imaging), synovial liquid exam (polarized compensated light microscopy and calcium quantification at the same day of synovial liquid aspiration and after 96 hours) were performed. The diagnosis of inflammatory osteoarthritis was given according to these findings. Results: Eleven patients, among the initial twenty, presented inflammatory osteoarthritis and chondrocalcinosis was observed in two of them. Chondrocalcinosis was detected by Rx, TC scan and MRI in one and just by TC in the other. As for the other nine subjects, just one presented chondrocalcinosis on TC scan. There was no difference regarding synovial liquid calcium measurements. Conclusion: It was not possible to establish a correlation between calcium pyrophosphate crystals and knee osteoarthritis / Mestrado / Clinica Medica / Mestre em Clinica Medica

D.Phil. (Chemistry) / The formation ofcalcium carbonate scale is a major problem in industry as well as in households. The scale that forms acts as an insulator, decreasing the effectiveness ofheat exchangers, be it a water cooling systems or a water heating system This raises the energy costs ofthat company and the costs of cleaning are expensive. Physical water treatment has been used for at least 50 years in the treatment ofwater with scale forming potential to reduce the formation ofthis scale. In thisthesis, tests were made on a magnetic and constantelectric field antiscaling device on the effect they have, ifany, on CaC03 scale formation. An attempt will be made to give a mechanism for any effect found. It is hoped that a contribution is made by this research in clearing up the misconceptions that abound in this controversial field ofphysical water treatment. Water with a high calcium bicarbonate content was exposed to the antiscaling devices and then calcium carbonate was forced to precipitate out ofsolution. This precipitation was followed by meauring the pH and the crystal structure ofthe precipitated calcium carbonate was studied. The most important results were that by exposing the calcium bicarbonate solution to an antiscalingdevice, the start ofprecipitation ofthe calcium carbonate was significantly delayed and the crystal structure of the calcium carbonate that formed was predominantly aragonite as opposed to calcite that usually formed.

Atrial fibrillation (AF), is characterised by rapid, irregular atrial stimulation, which leads to reduced contraction, resulting in a negative force-frequency-relationship (FFR). It is thought that rapid stimulation frequencies, which are synonymous with AF, disturb excitation-contraction-coupling (ECC). Ageing increases both the prevalence and economic impact of AF progressively. Although mechanisms underlying AF have been investigated in human and animal models, the cellular electrophysiology, and molecular changes that render the atria in aged individuals more susceptible to AF, still remain poorly understood. To our knowledge, there are no data investigating the effects of rapid stimulation frequencies on the Ca2+ handling within atrial myocytes, of a larger mammal, which are able to maintain AF, and is physiologically relevant to the human. To investigate this, sheep atrial myocytes were isolated, via enzymatic digestion. Measurements of intracellular Ca2+ ([Ca2+]i) were obtained via analysis of fluorescence (Fluo 5F am). Electrophysiological experiments were performed via the perforated-patch clamp technique, under voltage-clamp stimulation, to assess measurements of [Ca2+]i and trans-sarcolemmal currents. All voltage clamp experiments were performed at 37°C. Analysis of CaMKII inhibition, on Ca2+ wave frequency, was performed in non-stimulated atrial myocytes, at room temperature. Increased stimulation frequency (from 1Hz – 5Hz) had a significant impact on Ca2+ handling and trans-sarcolemmal currents within the atria. A reduction in Ca2+ transient amplitude was observed with increased rate. This was achieved despite increases in SR Ca2+ content, which were due to increased SERCA activity. The reduction in Ca2+ transient amplitude was attributed to reduced L-type Ca2+ current (ICa-L). Ageing augmented the rise in diastolic [Ca2+]i which was observed with rate, but with no further impac on Ca2+ transient amplitude. The rate dependent increase in SR Ca2+ content was augmented with age, and was presumed to be as a result of a reduction in ICa-L.By sensitising the ryanodine receptor (RyR), with low-dose caffeine (500 μmol.l-1), the fractional release of the first Ca2+ transient upon application was exacerbated by an increase in rate. This rapidly decayed to control levels at all stimulation frequencies. This data suggests that increases in RYR sensitivity lead to a greater Ca2+ release from the SR, for a given trigger. By ceasing stimulation there was potentiation of the first Ca2+ transient, post-rest, in comparison to pre-rest at 1Hz. This was augmented by increased rate. As ICa-L was unaltered between pre- and post-rest, within each frequency, it was assumed that the increased SR Ca2+ content with rate, coupled with continued SR Ca2+ uptake during the rest period, enhanced the fractional SR Ca2+ release for a given trigger, thus potentiating the amplitude of the Ca2+ transient. However, this requires further investigation. Other data found that CaMKII inhibition (via KN93) had no effect on Ca2+ wave frequency in control, or heart failure (HF), non-stimulated sheep atrial myocytes, which suggests either CaMKII is not up-regulated in the HF model used, or the concentration of KN93 used was insufficient. Further investigation is required in this area. The alterations in the mechanisms that modulate SR Ca2+ release and uptake are affected by alterations in stimulation frequency, which alter key modulators of contractile force.

Carta al Editor

White lime is used in many industries in South Africa but is not produced locally and must be imported. Many technologies have been suggested for the large-scale manufacture of calcium carbonate but these are not necessarily suitable for application in South Africa. This study investigated a chemical preparation of calcium carbonate combined with biological purification Calcium containing materials from the Pretoria Portland Cement, Lime Division factory at Lime Acres in the Northern Cape were studied as the starting materials for the manufacture. Investigation showed that they contained various impurities, including iron and manganese compounds which were largely responsible for the brown-grey colour of the lime products. Complete dissolution of calcium hydroxide, the purest of the potential starting materials, and subsequent hydroxide precipitation was not successful in removing all iron and manganese. Precipitation with sulfide ions was successfill, decreasing levels of metals to below the detection limit of atomic absorption spectrophotometry. Studies of all potential starting materials revealed that the levels of impurities in the starting material did not have a large effect on levels of impurities in the calcium carbonate produced. It was therefore possible to convert the residual calcium oxide or hydroxide in waste lime dusts to white calcium carbonate, a marketable prciduct Recycling of the water and starting material used in the process served to increase, rather than decrease, the purity of the calcium carbonate product. This allows for water conservation as water is not consumed in the process but merely utilised. When waste lime dust was used as the starting material, sulfate was found in the product. While still a white lime, the calcium carbonate was not chemically pure. Sulfate removal was therefore investigated and the use of sulfate-reducing bacteria was studied as a novel application. A mixed sulfate-reducing bacterial population was isolated and found to be hIghly active at sulfate concentrations between 0.2 and 2 ~~~. They were capable of autotrophic growth and could reduce sulfate in solutions with elevated pH and in calcium carbonate suspensions, although they did not grow readily in these media. A process was designed for the production of bulk quantities of calcium carbonate making use of the facilities and materials available at Lime Acres. This was tested using a small scale bench-top reactor series, with favourable results. The process would allow automatic, continuous production of large quantities of white lime using waste lime dust. Provision was also made for manufacture of smaller quantities of pure calcium carbonate using sulfate-reducing bacteria to remove the sulfate impurity.

No description available.

A series of three balance experiments were conducted to study the effect of the addition of animal fat to the diet on the utilization of calcium by growing chicks. In two experiments, the chicks were fed diets containing four levels of calcium, 0.75%, 1.0%, 1.25% and 1.50%, with a calcium: phosphorus ratio of 1.7:1. A fifth treatment was fed in which the top calcium level was adjusted to provide a calcium:phosphorus ratio of 2.5:1. All diets fed contained an excess of Vitamin D. Each of the five mineral treatments was fed as a control diet, to which no supplemental fat was added, and as a high fat diet, in which 8% of ground cellulose was replaced by 8% animal fat. In one experiment the diets contained 24% protein. In the other, the protein level was reduced to 20.6%. In the third experiment, to clarify the effect of adjusting the calcium:phosphorus ratio in the diet, three levels of calcium were fed with calcium:phosphorus ratios of approximately 1.5:1 and 2:1. As in the previous experiments, the different mineral levels were fed as low fat diets, and as high fat diets containing 8% animal fat. The diets fed in this experiment contained 23.6% protein. Criteria of calcium utilization used in all these experiments were rate of growth, feed efficiency, calcium balance (% of calcium retained) and calcium retention (calcium retained per 100 grams of gain in body weight). In addition, in the first two experiments, the percentage of bone ash was determined on a sample of chicks from each group at the conclusion of the experiment. It was found that: 1. The calcium requirement for growth and feed efficiency was not affected by the addition of 8% animal fat to the diet. The calcium requirement for maximum growth when the diet contained 24% protein appeared to be between 1.0 and 1.25% of the diet. All levels of calcium fed provided equal growth with diets containing 20.7% protein. 2. The addition of 8% fat to the diet significantly impaired bone calcification when the diet contained 24% protein. No impairment was evident at the 20.7% protein level. Diets containing 1% calcium provided calcification equal to that provided by diets containing 1.25% or 1.5% calcium. 3. Calcium balance (% of calcium retained) was found to be influenced excessively by differences in feed efficiency. A more useful index of calcium utilization was calcium retention, expressed in terms of body weight. 4. The addition of 8% animal fat to the diet impaired calcium retention (expressed as calcium retained per unit gain in weight) when the diet contained 1% to 1.5% calcium. In the case of the low fat diets, calcium retention rose as the level of calcium in the diet was increased to 1.25%, and remained constant as the calcium level was increased further to 1.5%. When fat was added to the diet, calcium retention rose more slowly as the calcium level was increased, and failed to reach the maximum retention of the low fat diets. The degree to which calcium retention was reduced was not sufficient to affect growth, in the presence of vitamin D above the usual allowance. 5. The addition of 8% animal fat to diets containing 24% protein increased the rate of growth and improved feed efficiency. The addition of fat to diets containing 20.7% protein did not affect the rate of growth and had little, if any, effect on feed efficiency. 6. Adjusting the calcium:phosphorus ratio of the diet within the limits tested did not affect growth, calcification, or calcium retention. / Land and Food Systems, Faculty of / Graduate

The magneto-optical Faraday effect was used, to observe the spin-bath relaxation in Europium doped CaF₂ crystals at helium temperatures from 1.5 to 4.2° K. Theory shows that the magnitude of the Faraday rotation is proportional to the difference in population of the ground state doublet. The experimental method used in this thesis is the same as that which was successfully used by Glattli and by Griffiths. Pulsed microwave power at X-band frequencies was employed to disturb the equilibrium between the spin system and the bath. The observed relaxation time t was expected to have a T⁻¹ temperature dependence hut because of the orientation of the crystal in our dc magnetic field which resulted in the seven transition lines being close together, cross-relaxation effects produced a temperature dependence of approximately T⁻². It is suggested that exchange coupled pairs of Eu²⁺ and clusters involving Eu³⁺ may account for this temperature dependence rather than there being a phonon bottleneck present. The field dependence of the relaxation time was found not to be directly related to the resonance spectrum, The Eu²⁺ concentration of the crystals used in this thesis was .2% / Science, Faculty of / Physics and Astronomy, Department of / Graduate