954 resultados para Biochemical and Biomolecular Engineering
Resumo:
Chronic kidney disease (CKD) is a worldwide health problem, with adverse outcomes of cardiovascular disease and premature death. The ageing of populations along with the growing prevalence of chronic diseases such as diabetes and hypertension is leading to worldwide increase in the number of CKD patients. It has become evident that inflammation plays an important role in the pathogenesis of atherosclerosis complications. CKD patients also have an increased risk of atherosclerosis complications (including myocardial infarction, sudden death to cardiac arrhythmia, cerebrovascular accidents, and peripheral vascular disease). In line with this, oral and dental problems can be an important source of systemic inflammation. A decline in oral health may potentially act as an early marker of systemic disease progression. This series of studies examined oral health of CKD patients from predialysis, to dialysis and kidney transplantation in a 10-year follow-up study and in a cross-sectional study of predialysis CKD patients. Patients had clinical and radiographic oral and dental examination, resting and stimulated saliva flow rates were measured, whilst the biochemical and microbiological composition of saliva was analyzed. Lifestyle and oral symptoms were recorded using a questionnaire, and blood parameters were collected from the hospital records. The hypothesis was that the oral health status, symptoms, sensations, salivary flow rates and salivary composition vary in different renal failure stages and depend on the etiology of the kidney disease. No statistically significant difference were seen in the longitudinal study in the clinical parameters. However, some saliva parameters after renal transplantation were significantly improved compared to levels at the predialysis stage. The urea concentration of saliva was high in all stages. The salivary and plasma urea concentrations followed a similar trend, showing the lowest values in kidney transplant patients. Levels of immunoglobulin (Ig) A, G and M all decreased significantly after kidney transplantation. Increased concentrations of IgA, IgG and IgM may reflect disintegration of the oral epithelium and are usually markers of poor general oral condition. In the cross-sectional investigation of predialysis CKD patients we compared oral health findings of diabetic nephropathy patients to those with other kidney disease than diabetes. The results showed eg. more dental caries and lower stimulated salivary flow rates in the diabetic patients. HbA1C values of the diabetic patients were significantly higher than those in the other kidney disease group. A statistically significant difference was observed in the number of drugs used daily in the diabetic nephropathy group than in the other kidney disease group. In the logistic regression analyses, age was the principal explanatory factor for high salivary total protein concentration, and for low unstimulated salivary flow. Poor dental health, severity of periodontal disease seemed to be an explanatory factor for high salivary albumin concentrations. Salivary urea levels were significantly linked with diabetic nephropathy and with serum urea concentrations. Contrary to our expectation, however, diabetic nephropathy did not seem to affect periodontal health more severely than the other kidney diseases. Although diabetes is known to associate with xerostomia and other oral symptoms, it did not seem to increase the prevalence of oral discomfort. In summary, this series of studies has provided new information regarding the oral health of CKD patients. As expected, the commencement of renal disease reflects in oral symptoms and signs. Diabetic nephropathy, in particular, appears to impart a requirement for special attention in the oral health care of patients suffering from this disease.
Resumo:
A simple three step procedure was used to purify microsomal NADH-cytochrome b5 (ferricyanide) reductase to homogeneity from the higher plant C. roseus. The microsomal bound reductase was solubilized using zwitterionic detergent-CHAPS. The solubilized reductase was subjected to affinity chromatography on octylamino Sepharose 4B, blue 2-Sepharose CL-6B and NAD+-Agarose. The homogeneous enzyme has an apparent molecular weight of 33,000 as estimated by SDS-PAGE. The purified enzyme catalyzes the reduction of purified cytochrome b5 from C. roseus in the presence of NADH. The reductase also readily transfers electrons from NADH to ferricyanide (Km 56 μM), 2,6-dichlorophenolindophenol (Km 65 μM) and cytochrome Image via cytochrome b5 but not to menadione.
Resumo:
The synthesis of 8-aminoquinolines and 1,10-phenanthrolines with substituents in alpha of the nitrogen has been performed through an inverse-demanding aza-Diels-Alder (Povarov reaction) in the fluoroalcohols TFE or HFIP. This path involves simple starting materials: 1,2-phenylenediamines, enol ethers and aldehydes.
Resumo:
Soils showing changes in plasticity characteristics upon driving form an important group in tropical soils. These changes are attributed to the grouping of particles into aggregates either due to mineralogy or presence of cementing agents and/or pore fluid characteristics. These changes are found to be permanent. In this paper, the effect of these changes leading to changes in index properties is discussed. The coefficient of permeability has been found to be comparable at liquid limit water content for different soils of varying liquid limit values. Permeability is an indirect reflection of microstructure and indicates the flow rate, which depends upon pore geometry. Other mechanical properties like compressibility and shear strength also depend upon pore geometry. These microstructural aspects of liquid limit as a reference state for the analysis of engineering behavior of tropical soils are examined in detail.
Resumo:
CaSiO3:Eu3+ (1-5 mol%) red emitting phosphors have been synthesized by a low-temperature solution combustion method. The phosphors have been well characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and optical spectroscopy. PXRD patterns reveal monoclinic CaSiO3 phase can be obtained at 900 degrees C. The SEM micrographs show the crystallites with irregular shape, mostly angular. Upon 254 nm excitation, the phosphor show characteristic fluorescence D-5(0) -> F-7(J) (J = 0, 1, 2, 3, 4) of the Eu3+ ions. The electronic transition located at 614 nm corresponding to D-5(0) -> F-7(2) of Eu3+ ions, which is stronger than the magnetic dipole transition located at 593 nm corresponding to D-5(0) -> F-7(1) of Eu3+ ions. Different pathways involved in emission process have been studied. Concentration quenching has been observed for Eu3+ concentration >4 mol%. UV-visible absorption shows an intense band at 240 nm in undoped and 270 nm in Eu3+ doped CaSiO3 which is attributed to oxygen to silicon (O-Si) ligand-to-metal charge-transfer (LMCT) band in the SiO32- group. The optical energy band gap is widened with increase of Eu3+ ion dopant. (C) 2010 Elsevier B.V. All rights reserved.
Resumo:
Amorphous SiO2 thin films were prepared on glass and silicon substrates by cost effective sol-gel method. Tetra ethyl ortho silicate (TEOS) was used as the precursor material, ethanol as solvent and concentrated HCl as a catalyst. The films were characterized at different annealing temperatures. The optical transmittance was slightly increased with increase of annealing temperature. The refractive index was found to be 1.484 at 550 nm. The formation of SiO2 film was analyzed from FT-IR spectra. The MOS capacitors were designed using silicon (1 0 0) substrates. The current-voltage (I-V), capacitance-voltage (C-V) and dissipation-voltage (D-V) measurements were taken for all the annealed films deposited on Si (1 0 0). The variation of current density, resistivity and dielectric constant of SiO2 films with different annealing temperatures was investigated and discussed for its usage in applications like MOS capacitor. The results revealed the decrease of dielectric constant and increase of resistivity of SiO2 films with increasing annealing temperature. (C) 2010 Elsevier B.V. All rights reserved.
Resumo:
Angiotensin converting enzyme (ACE) catalyzes the conversion of angiotensin I (Ang I) to angiotensin II (Ang II). ACE also cleaves the terminal dipeptide of vasodilating hormone bradykinin (a nonapeptide) to inactivate this hormone. Therefore, inhibition of ACE is generally used as one of the methods for the treatment of hypertension. `Oxidative stress' is another disease state caused by an imbalance in the production of oxidants and antioxidants. A number of studies suggest that hypertension and oxidative stress are interdependent. Therefore, ACE inhibitors having antioxidant property are considered beneficial for the treatment of hypertension. As selenium compounds are known to exhibit better antioxidant behavior than their sulfur analogues, we have synthesized a number of selenium analogues of captopril, an ACE inhibitor used as an antihypertensive drug. The selenium analogues of captopril not only inhibit ACE activity but also effectively scavenge peroxynitrite, a strong oxidant found in vivo.
Resumo:
We have synthesized five new cholesterol based gemini cationic lipids possessing hydroxyethyl (-CH2CH2OH) function on each head group, which differ in the length of the polymethylene spacer chain. These gemini lipids are important for gene delivery processes as they possess pre-optimized molecular features, e. g., cholesterol backbone, ether linkage and a variable spacer chain between both the headgroups of the gemini lipids. Cationic liposomes were prepared from each of these lipids individually and as a mixture of individual cationic gemini lipid and 1,2-dioleoyl phosphatidylethanolamine (DOPE). Each gemini lipid based formulation induced better transfection activity than that of their monomeric counterpart. One such gemini lipid with a -(CH2)(12)-spacer, HG-12, showed dramatic increase in the mean fluorescence intensity due to the expression of green-fluorescence protein (GFP) in the presence of 10% FBS compared to the conditions where there was no serum. Other gemini lipids retained their gene transfection efficiency without any marked decrease in the presence of serum. The only exception was seen with the gemini with a -(CH2)(3)-spacer, HG-3, which on gene transfection in the presence of 10% FBS lost similar to 70% of its transfection efficiency. Overall the gemini lipid with a -(CH2)(5)-spacer, HG-5, showed the highest transfection activity at N/P (lipid/DNA) ratio of 0.5 and lipid : DOPE molar ratio of 2. Upon comparison of the relevant parameters, e. g., %-transfected cells, the amount of DNA transfected to each cell and %-cell viability all together against Lipofectamine 2000, one of the best commercial transfecting agents, the optimized lipid formulation based on DOPE/HG-5 was found to be comparable. In terms of its ability to induce gene-transfer in the presence of serum and shelf-life DOPE/HG-5 liposome was found to be superior to its commercial counterpart. Confocal imaging analysis confirmed that in the presence of 10% serum using a Lipid : DOPE of 1 : 4 and N/P charge ratio of 0.75 with 1.2 mu g DNA per well, HG-5 is better than Lipofectamine 2000.
Resumo:
The coordinating behavior of a new dihydrazone ligand, 2,6-bis(3-methoxysalicylidene) hydrazinocarbonyl]pyridine towards manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) has been described. The metal complexes were characterized by magnetic moments, conductivity measurements, spectral (IR, NMR, UV-Vis, FAB-Mass and EPR) and thermal studies. The ligand crystallizes in triclinic system, space group P-1, with alpha=98.491(10)degrees, beta=110.820(10)degrees and gamma=92.228(10)degrees. The cell dimensions are a=10.196(7)angstrom, b=10.814(7)angstrom, c=10.017(7)angstrom, Z=2 and V=1117.4(12). IR spectral studies reveal the nonadentate behavior of the ligand. All the complexes are neutral in nature and possess six-coordinate geometry around each metal center. The X-band EPR spectra of copper(II) complex at both room temperature and liquid nitrogen temperature showed unresolved broad signals with g(iso) = 2.106. Cyclic voltametric studies of copper(II) complex at different scan rates reveal that all the reaction occurring are irreversible. (C) 2011 Elsevier B.V. All rights reserved.
Resumo:
Seepage effects on the stability, mobility, and incipient motion of sand-bed particles are experimentally investigated. Seepage through a sand bed in a downward direction (suction) reduces the stability of particles, and it can even initiate their movement. The bed erosion is increased with the increased rates of suction. Whereas the seepage in an upward direction (injection) increases the stability of bed particles, it does not aid initiating their movement. The rate of bed erosion is reduced or even stopped by the increased infection rates. Hydrodynamic conditions leading to the so-called "pseudoincipient motion'' with suction (for the initiation of particles movement that are otherwise at rest under no-seepage conditions), and with injection (for only arresting the particles movement that are otherwise moving initially) are evaluated. The conventional Shields curve cannot be used to predict such pseudoincipient motion conditions with seepage. The concepts thus developed are useful for a better understanding of the sediment transport mechanics and in the design of stable alluvial channels affected by seepage.
Resumo:
Nanocrystalline ZnO:Mn (0.1 mol%) phosphors have been successfully prepared by self propagating, gas producing solution combustion method. The powder X-ray diffraction of as-formed ZnO:Mn sample shows, hexagonal wurtzite phase with particle size of similar to 40 nm. For Mn doped ZnO, the lattice parameters and volume of unit cell (a=3.23065 angstrom, c=5.27563 angstrom and V=47.684 (angstrom)(3)) are found to be greater than that of undoped ZnO (a=3.19993 angstrom, c=5.22546 angstrom and V=46.336 (angstrom)(3)). The SEM micrographs reveal that besides the spherical crystals, the powders also contained several voids and pores. The TEM photograph also shows the particles are approximately spherical in nature. The FTIR spectrum shows two peaks at similar to 3428 and 1598 cm(-1) which are attributed to O-H stretching and H-O-H bending vibration. The PL spectra of ZnO:Mn indicate a strong green emission peak at 526 nm and a weak red emission at 636 nm corresponding to T-4(1) -> (6)A(1) transition of Mn2+ ions. The EPR spectrum exhibits fine structure transition which will be split into six hyperfine components due to Mn-55 hyperfine coupling giving rise to all 30 allowed transitions. From EPR spectra the spin-Hamiltonian parameters have been evaluated and discussed. The magnitude of the hyperfine splitting (A) constant indicates that there exists a moderately covalent bonding between the Mn2+ ions and the surrounding ligands. The number of spins participating in resonance (N), its paramagnetic susceptibility (chi) have been evaluated. (C) 2011 Elsevier B.V. All rights reserved.
Resumo:
Two vitellins, VtA and VtB, were purified from the eggs of Dysdercus koenigii by gel filtration and ion exchange chromatography. VtA and VtB have molecular weights of 290 and 260 kDa, respectively. Both Vts are glycolipoproteinaceous in nature. VtA is composed of three polypeptides of M-r 116, 92 and 62 kDa while VtB contained an additional subunit of M-r 40 kDa. All subunits except the 116-kDa subunit are glycolipopolypeptides. Polyclonal antibody raised against VtA (anti-VtA antibody) cross-reacted with VtB and also with vitellogenic haemolymph and ovaries and pre-vitellogenic fat bodies, but not with haemolymph from either adult male, fifth instar female, or pre-vitellogenic females demonstrating sex and stage specificity of the Vts. Immunoblots in the presence of anti-VtA revealed two proteins (of 290 and 260 kDa) in both vitellogenic haemolymph and pre-vitellogenic fat bodies that are recognised as D. koenigii Vgs. In newly emerged females, Vgs appeared on day 1 in fat bodies and on day 3 in haemolymph and ovaries. Vg concentration was maximum on day 2 in fat body, day 4 in haemolymph and day 7 in ovary. Although the biochemical and temporal characteristics of these proteins show similarity to some hemipterans, they are strikingly dissimilar with those of a very closely related species. (C) 1999 Elsevier Science Inc. All rights reserved.