Synthesized of Sporopollenin-Immobilized Schiff Bases and Their Vanadium(IV) Sorption Studies

This study investigated the potential use of a biologic polymer Lycopodium clavatum spores (Sporopollenin) for removal of vanadium ions (V(IV)) from aqueous solution. Three Schiff base derivative compounds immobilized sporopollenin were prepared and characterized. Immobilized sporopollenin was characterized via a scanning electron microscope, elemental analysis, infrared spectroscopy and thermal analysis techniques. The sorption capacities of the immobilized surfaces toward V(IV) ions were investigated by batch sorption experiments. V(IV) concentration, initial pH and the temperature effects were studied. The isotherm data of V(IV) ions were correlated reasonably well both Langmuir, Freundlich sorption isotherm. The thermodynamic studies showed that the V(IV) sorption onto immobilized sporopollenin derivatives is a spontaneous, endothermic and a chemical reaction.     

Enhanced recovery from acute renal failure by the postischemic infusin of adenine nucleotides and magnesium chloride in rats

Although a number of manipulations prior to or during the initiation phase of an acute renal injury will modify the degree of functional impairment, agents administered after the acute insult usually have been ineffective. In the present study, adenine nucleotides (AMP, ADP, or ATP) combined with magnesium chloride were infused after an ischemic renal injury. Twenty-four hours later: (1) rats that received no infusion or one of the components of the mixture alone had reduced CIn (355 +/- 40 microliter/min/100 g of body wt vs. 977 +/- 40 control value), decreased RBF (3550 +/- 205 microliter/min/100 g of body wt vs. 5095 +/- 171 control value), elevated FENa (0.65 +/- 0.10% vs. 0.17 +/- 0.04 control value), and diminished UOsm (862 +/- 110 mOsm/kg vs. 1425 +/- 132 control value); (2) rats given dopamine or phenoxybenzamine maintained low CIn (365 +/- 50) despite improved RBF (4678 +/- 222); (3) rats infused with either AMP, ADP, or ATP combined with magnesium chloride had markedly improved CIn (594 +/- 44, P < 0.01), increased RBF (4269 +/- 223, P < 0.01); normalized FENa (0.18 +/- 0.07%, P < 0.01), and improved UOsm (1201 +/- 106 mOsm/kg, P < 0.05). In animals given no infusion or only magnesium chloride, ultrastructural studies demonstrated focal cellular necrosis and marked generalized tubular cell and mitochondrial swelling, whereas rats infused with ATP and magnesium chloride had fewer ultrastructural changes with better preservation of cellular morphology. Rats treated with ATP and magnesium chloride had improved CIn despite ischemic periods of 30, 45, and 60- min; and the degree of improvement was directly related to the quantity of ATP and magnesium chloride administered. The cellular content of exogenously administered ATP was 2.5 times greater in previously ischemic kidneys than in nonischemic kidneys. The data indicate that adenine nucleotides combined with magnesium chloride when infused after the initiation of acute renal failure significantly improve both CIn and tubular function and suggest that these agents effectively enhance recovery following an ischemc renal insult.     

Adsorption of Cu(II) onto silica gel-immobilized Schiff base derivative

4-chloroisonitroacetophenone 4-aminobenzylhydrazone (CAAH) chemically anchored on a silica gel surface, has been used for Cu(II) sorption from aqueous solution. The surface modification processes was performed after silanization of silica, then analyzed by elemental analysis, infrared spectroscopy, and thermogravimetry. The sorption behavior of copper(II) was evaluated by the use of batch and column methods. The influences of the concentration, temperature and pH for sorption on the immobilized silica gel with Schiff base were investigated. The obtained dynamic data were fitted to Freundlich, Langmuir and Dubinin-Raduskevich (D-R) isotherms. The mean sorption energy (E) of copper sorption onto silica gel was calculated from D-R isotherm indicating a chemical ion-exchange. The thermodynamic parameters such as Gibbs free energy change, enthalpy change and entropy change were calculated from the adsorption isotherms which were used to explain the mechanism of the adsorption.     

A new pathway for transmembrane electron transfer in photosynthetic reaction centers of Rhodobacter sphaeroides not involving the excited special pair

It is generally accepted that electron transfer in bacterial photosynthesis is driven by the first singlet excited state of a special pair of bacteriochlorophylls (P*). We have examined the first steps of electron transfer in a mutant of the Rhodobacter sphaeroides reaction center in which charge separation from P* is dramatically slowed down. The results provide for the first time clear evidence that excitation of the monomeric bacteriochlorophyll in the active branch of the reaction center (B(A)) drives ultrafast transmembrane electron transfer without the involvement of P*, demonstrating a new and efficient mechanism for solar energy transduction in photosynthesis. The most abundant charge-separated intermediate state probably is P+B(A)-, which is formed within 200 fs from B(A)* and decays with a lifetime of 6.5 ps into P+H(A)-. We also see evidence for the involvement of a B(A)+H(A)- state in the alternative pathway.     

Isotherms and thermodynamics for the sorption of heavy metal ions onto functionalized sporopollenin

In this study, sporopollenin of Lycopodium clavatum spores was used for the sorption experiment. Glutaraldehyde (GA) immobilized sporopollenin (Sp), is employed as a sorbent in sorption of selected heavy metal ions. The sorbent prepared by sequential treatment of sporopollenin by silanazing compound and glutaraldehyde is suggested for sorption of Cu(II), Zn(II) and Co(II) from aqueous solutions. Experimental conditions for effective sorption of heavy metal ions were optimized with respect to different experimental parameters using batch method in detail. Optimum pH range of Cu(II) has occurred at pH ≥ 5.5 and Zn(II), Co(II) at pH ≥ 5.0, for the batch method. All of the metal ions can be desorbed with 10 cm³ of 0.5 mol dm⁻³ of ethylenediaminetetraacetic acid (EDTA) solution. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm equations were applied to the experimental data. Thermodynamic parameters such as free energy (ΔG^o), entropy (ΔS^o) and enthalpy (ΔH^o) were also calculated from the sorption results used to explain the mechanism of the sorption. The results indicated that this sorbent is successfully employed in the separation of trace Cu(II), Zn(II) and Co(II) from the aqueous solutions.     

Sorption of heavy metal ions by glass beads-immobilized calix[4]arenes derivative

Glass beads (GB) immobilized, 5,11,17,23-tetra-tert-butyl-25,27-diethoxycarbonylmethoxy-26,28-dihydroxycalix[4]arene (CA) are prepared and used as a new sorbent in sorption study of removal heavy metal ions. A calixarene derivative bonded to amino-functionalized glass beads sorbent was synthesized via a self assembly technique for sorbent of selected heavy metal ions in aqueous. In order to absorb selected heavy metal ions in aqueous, a calixarene derivative bonded to amino-functionalized glass beads sorbent was synthesized via a self assembly technique. The sorbent which is named GB-APTS-CA was characterized using infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), elemental analysis and thermal analysis (TGA/DTG). The influences of some experimental parameters including pH of the sample solution, weight of sorbent, concentration and temperature have been investigated. The sorption data were evaluated using the Langmuir, Freundlich and Dubinin Radushkevich (D-R) isotherm. The obtained maximum sorption capacity for Cu(II), and Pb(II) is 0.06 mmol g^?1 and 0.02 mmol g^?1, respectively. Thermodynamic parameters such as the standard free energy change (ΔG○), enthalpy change (ΔH○) and entropy change (ΔS○) were calculated to determine the nature of sorption process. Thus, GB-APTS-CA is favorable and useful for the removal of Cu(II) and Pb(II) metal ions.     

Comparative effect of tiaprofenic acid and piroxicam alone and as adjuvants to praziquantel in Schistosoma mansoni infected mice

A simple, rapid and sensitive two column-switching high-performance liquid chromatographic (HPLC) method with ultraviolet detection at 210 nm has been developed for the determination of N-(trans-4-isopropylcyclohexanecarbonyl)-D-phenylalanine (AY4166, I) and its seven metabolites in human plasma and urine. Measurements of I and its metabolites were carried out by two column-switching HPLC, because metabolites were classified into two groups according to their retention times. After purification of plasma samples using solid-phase extraction and direct dilution of urinary samples, I and each metabolite were injected into HPLC. The calibration graphs for plasma and urinary samples were linear in the ranges 0.1 to 10 microg ml(-1) and 0.5 to 50 microg ml(-1), respectively. Recoveries of I and its seven metabolites were over 88% by the standard addition method and the relative standard deviations of I and its metabolites were 1-6%.     

Anterior vertebral body screw pullout testing. A comparison of Zeilke, Kaneda, Universal Spine System, and Universal Spine System with pullout-resistant nut

STUDY DESIGN: A biomechanical study of pullout of anteriorly implanted screws in cadaveric vertebral bodies. OBJECTIVES: To investigate and compare the pullout strength of the Zielke, Kaneda, Universal Spine System (USS) pedicle screw, and USS pedicle screw with a new pullout-resistant nut. SUMMARY OF BACKGROUND DATA: A common problem with anterior purchase regardless of the implant system is screw pullout at the proximal and distal ends of multilevel constructs. There is limited information on a solution to this problem. METHODS: The L1 to L4 vertebral bodies from four cadavers had one each of Zielke and Kaneda pedicle screws (Acromed Corp., Cleveland, OH), USS pedicle screw (Synthes Spine, Paoli, PA), and USS pedicle screw with pullout-resistant nut implanted transversely across the center of the vertebral body with bicortical purchase in a similar fashion as would be used clinically. The screws were extracted using a servohydraulic material testing system. The maximum axial forces were recorded. RESULTS: The Zielke and Kaneda screws had no significant difference in mean pullout strength (P = 0.542). The USS screw alone was less strong (P = 0.009). The USS screw and pullout-resistant nut increased the pullout strength by twofold (P = 0.00006). In the screw pullout tests, the mode of failure was at the screw thread's interface. The USS screw and pullout-resistant nut failed by imploding the body around the nut. With the USS screw and pullout-resistant nut, the pullout strength was determined by the compressive strength of the bone. CONCLUSIONS: The addition of a pullout-resistant nut to an anterior vertebral body screw improves the pullout strength by twofold and changes the mode of failure to rely ultimately on the inherent vertebral body strength rather than the screw's characteristics. The addition of a pullout-resistant nut may be applicable to multilevel implant constructs to prevent screw pullout at the top and bottom.     

The lipid phosphatase activity of PTEN is critical for its tumor supressor function

Since their discovery, protein tyrosine phosphatases have been speculated to play a role in tumor suppression because of their ability to antagonize the growth-promoting protein tyrosine kinases. Recently, a tumor suppressor from human chromosome 10q23, called PTEN or MMAC1, has been identified that shares homology with the protein tyrosine phosphatase family. Germ-line mutations in PTEN give rise to several related neoplastic disorders, including Cowden disease. A key step in understanding the function of PTEN as a tumor suppressor is to identify its physiological substrates. Here we report that a missense mutation in PTEN, PTEN-G129E, which is observed in two Cowden disease kindreds, specifically ablates the ability of PTEN to recognize inositol phospholipids as a substrate, suggesting that loss of the lipid phosphatase activity is responsible for the etiology of the disease. Furthermore, expression of wild-type or substrate-trapping forms of PTEN in HEK293 cells altered the levels of the phospholipid products of phosphatidylinositol 3-kinase and ectopic expression of the phosphatase in PTEN-deficient tumor cell lines resulted in the inhibition of protein kinase (PK) B/Akt and regulation of cell survival.