Renal cell carcinoma survival and body mass index: a dose-response meta-analysis reveals another potential paradox within a paradox.

BACKGROUND: In healthy subjects increasing body mass index (BMI) leads to greater mortality from a range of causes. Following onset of specific diseases, however, the reverse is often found: called the 'obesity paradox'. But we recently observed the phenomenon called the 'paradox within the paradox' for stroke patients. OBJECTIVE: The objective of our study was to examine the effect of each unit increase in BMI on renal cancer-specific survival (CSS), cancer-specific mortality, overall survival (OS) and overall mortality. DESIGN: Random-effects generalized least squares models for trend estimation were used to analyze the data. Eight studies, comprising of 8699 survivals of 10 512 renal cell carcinoma (RCC) patients met the inclusion criteria, including 5 on CSS and 3 on OS. RESULTS: The association of BMI with CSS and OS was non-linear (P<0.0001, P=0.004, respectively). We observed that CSS increased in relation to BMI, indicating that there was the obesity paradox in RCC. However, each unit increase in BMI over 25 was associated with decreased OS, indicating that RCC may also exhibit a paradox within the paradox. CONCLUSIONS: Inconsistent effects of increases in BMI on CSS and OS, as previously observed for stroke, creates a paradox (different directions of mortality for different causes) within the obesity paradox.

Application of modified nano-alumina as a solid phase extraction sorbent for the preconcentration of Cd and Pb in water and herbal samples prior to flame atomic absorption spectrometry determination.

The first study on the high efficiency of nanometer-sized gamma-alumina coated with sodium dodecyl sulfate-1-(2-pyridylazo)-2-naphthol (SDS-PAN) as a new sorbent solid phase extraction (SPE) has been reported. A microcolumn packed with modified nanometer-sized alumina was used to preconcentrate and separate Cd and Pb in water and herbal samples. The metals were eluted with 2 mL HNO(3) directly and detected with the detection system flame atomic absorption spectrometry (FAAS). Various influencing parameters on the separation and preconcentration of trace metals, such as pH, flow rate, sample volume, amount of sorbent, and concentration of eluent, were studied. Under the optimized operating conditions, the sorption capacities of the modified nano-gamma-alumina for Cd and Pb were 11.1 and 16.4 mg g(-1) respectively. With 500.0 mL sample an enrichment factor of 250 was obtained. The detection limits of this method for Cd and Pb were 0.15 and 0.17 microg L(-1) and the R.S.D.s were 2.8 and 3.2% (n=10), respectively. The proposed method has been applied to the determination of these metal ions at trace levels in certified reference materials and real samples with satisfactory results.

Laser induced-thermal lens spectrometry after cloud point extraction for the determination of trace amounts of palladium.

Cloud point extraction (CPE) in combination with thermal lens spectrometry (TLS) has been developed for the preconcentration and determination of palladium. TLS and CPE methods have good matching conditions for the combination because TLS is a suitable method for the analysis of low volume samples obtained after CPE. Palladium was complexed with 1-(2-pyridylazo)-2-naphthol (PAN) as a complexing agent in an aqueous medium and concentrated by octylphenoxypolyethoxyethanol (Triton X-114) as a surfactant. After the phase separation at 60 degrees C based on the cloud point extraction of the mixture, the surfactant-rich phase was dried and the remaining phase was dissolved using 20 microL of carbon tetrachloride. The obtained solution was introduced into a quartz microcell and the analyte was determined by laser induced-thermal lens spectrometry (LI-TLS). The single-laser TLS was used as a sensitive method for the determination of palladium-PAN complex in 20 microL of the sample. Under optimum conditions, the analytical curve was linear for the concentration range of 0.3-60 ng mL(-1) and the detection limit was 0.04 ng mL(-1). The enhancement factor of 460 was achieved for 10 mL samples containing the analyte and relative standard deviations were lower than 5%. The developed method was successfully applied to the extraction and determination of palladium in water samples.

Fiber optic-linear array detection spectrophotometry in combination with cloud point extraction for simultaneous preconcentration and determination of cobalt and nickel.

A new combined method including fiber optic-linear array detection spectrophotometry (FO-LADS) and cloud point extraction (CPE) was developed using a cylindrical micro cell for simultaneous preconcentration and determination of different species. The CPE and FO-LADS methods have good matching conditions for combination because FO-LADS is suitable as a detection technique for the low volume of remained phase obtained after CPE. This combination was carried out using 50 microL cylindrical micro cell and then employed for simultaneous preconcentration and determination of cobalt and nickel. Cloud point extraction method was based on the chromogenic reaction of metal ions and 1-(2-pyridylazo)-2-naphthol (PAN) and then preconcentration of formed complexes using octylphenoxypolyethoxyethanol (Triton X-114). The remained phase after CPE was transferred into cylindrical micro cell and located at the cell holder of FO-LADS. The spectra of cobalt and nickel complexes were collected by FO-LADS and processed for ordinary and first derivative spectrophotometry. Optimization of different parameters was evaluated. Under optimum conditions, calibration curves were linear in the range of 0.6-30.0 and 0.1-15.0 microg L(-1) with detection limits of 0.2 and 0.04 microg L(-1) for Co and Ni respectively. The relative standard deviations (R.S.D.s) were lower than 4%. The obtained enhancement factors were 198 and 199 for cobalt and nickel, respectively. The proposed method was compared with the other methods and applied to the analysis of several real and spiked samples.

Fiber optic-linear array detection spectrophotometry in combination with dispersive liquid-liquid microextraction for simultaneous preconcentration and determination of palladium and cobalt.

A new combined method including fiber optic-linear array detection spectrophotometry (FO-LADS) and dispersive liquid-liquid microextraction (DLLME) was developed using a cylindrical micro-cell for simultaneous preconcentration and determination of different species. DLLME and FO-LADS methods have good matching conditions for being combined since FO-LADS is a suitable method for the determination of analytes in low volume of the remained phase obtained after DLLME. DLLME technique was successfully used as a sample preparation method. In this preconcentration method, an appropriate mixture of ethanol (the disperser solvent) and 1,2-dichlorobenzene (the extraction solvent) was injected rapidly into the water sample containing palladium and cobalt after complex formation using 1-(2-pyridylazo)-2-naphthol (PAN) reagent. After phase separation, 50 microL of the sedimented phase containing enriched analytes was determined by FO-LADS. The ordinary and first derivative absorption spectra were obtained for optimization and simultaneous determination of palladium and cobalt, respectively. Under the optimum conditions, the calibration graphs were linear in the range of 2-100 microg L(-1) and 1-70 microg L(-1) with detection limit of 0.25 microg L(-1) and 0.2 microg L(-1) for palladium and cobalt, respectively. The relative standard deviations (R.S.D.s, n = 5) were lower than 4%. The enhancement factors of 162 and 165 were obtained for palladium and cobalt, respectively. The proposed method was compared with other methods and applied to the analysis of several real and synthetic samples with satisfactory results.

Laser induced-thermal lens spectrometry after cloud point extraction for the determination of trace amounts of rhodium.

A new combination method, employing thermal lens spectrometry (TLS) after cloud point extraction (CPE), has been developed for the preconcentration and determination of rhodium. TLS and CPE methods have good matching conditions for the combination because TLS is a suitable method for the analysis of low volume samples obtained after CPE. Rhodium was complexed with 1-(2-pyridylazo)-2-naphthol (PAN) as a complexing agent in an aqueous medium and concentrated by octylphenoxypolyethoxyethanol (Triton X-114) as a surfactant. After the phase separation at 50 degrees C based on the cloud point extraction of the mixture, the surfactant-rich phase was dried and the remaining phase was dissolved using 20muL of carbon tetrachloride. The obtained solution was introduced into a quartz micro cell and the analyte was determined by laser induced-thermal lens spectrometry (LI-TLS). The single laser TLS was used as a sensitive method for the determination of Rhodium-PAN complex in 20muL of the sample. Under optimum conditions, the analytical curve was linear for the concentration range of 0.5-50ngmL(-1) and the detection limit was 0.06ngmL(-1). The enhancement factor of 450 was achieved for 10mL samples containing the analyte and relative standard deviations were lower than 5%. The developed method was successfully applied to the extraction and determination of rhodium in water samples.

Preconcentration of chromium (III) and speciation of chromium by electrothermal atomic absorption spectrometry using cellulose adsorbent.

A simple and sensitive method has been developed for species selective determination of chromium(III) and chromium(VI) in water by electrothermal atomic absorption spectrometry. The procedure is based on selective absorption of Cr(III) on a cellulose micro column (pH 11, 0.5 mol L(-1) NaCl). Total chromium was subsequently determined after appropriate reduction of Cr(VI) to Cr(III). Recoveries of more than 97% were found. A concentration factor of 100 was achieved. The relative standard deviations (n=10) at the 40 ng L(-1) level for chromium(III) and chromium(VI) were 2.3% and 1.8% and corresponding limits of detection (based on 36) were 1.8 ng L(-1) and 5.1 ng L(-1), respectively. No interference effects have been observed from other investigated species and the method has been successfully applied to natural water samples.

Use of the triiodide-hexadecylpyridinium chloride micellar system for the kinetic determination of tungsten (VI).

The associate formed by triiodide ion and hexadecylpyridinium chloride (cetylpyridinium chloride (CPC)) micelles was used to enhance the kinetic spectrophotometric determination of W(VI) by its catalytic action on the oxidation of iodide with hydrogen peroxide in an acidic medium. The reaction was monitored spectrophotometrically by measuring the increase in absorbance of I(3)(-)-CPC associate at 525 nm by the fixed-time method of 3 min from initiation of the reaction. The micellar medium allowed the determination of W(VI) at concentrations between 4 and 90 ng ml(-1) with a detection limit of 2.4 ng ml(-1) (i.e. about 12-13 times lower than those of methods implemented in aqueous media). The relative standard deviation for nine replicate analyses was 0.03% for 76.6 ng ml(-1) of W(VI). The proposed method was applied to the determination of W(VI) in aqueous extracts of soil sample with no prior separation.

Chromium speciation by a surfactant-coated alumina microcolumn using electrothermal atomic absorption spectrometry.

A simple and convenient method has been developed for the speciation of chromium(III) and chromium(VI) in aqueous solutions using a sodium dodecyl sulphate coated alumina micro-column (1.5 cm x 5 mm i.d.) and graphite furnace-atomic absorption spectrometry (GF-AAS). Under the optimized conditions (pH 0.6, adjusted with hydrochloric acid; flow rate, 1 ml min(-1)) chromium(VI) is retained on the column and chromium(III) is collected and determined by GF-AAS. Total chromium is directly determined by GF-AAS and chromium(VI) is calculated by difference. The relative standard deviations (10 replicate analyses) at the 20 mug l(-1) level for chromium(III) and chromium(VI) and at the 40 mug l(-1) level for total chromium were 1.4%, 3.6% and 1.8%, and the corresponding limits of detection (based on 3sigma) were 0.57 mug ml(-1), 0.61 mug ml(-1) and 0.35 mug l(-1) respectively. No large interference effects have been observed from other investigated species and the method has been successfully applied to a range of water samples.

Electrochemical behaviour of some naturally occurring hydroxy derivatives of 9,10-anthraquinone in chloroform at mercury and glassy carbon electrodes: application of AC polarography to the analysis of rhubarb roots.

Electrochemical behaviour of some naturally occurring hydroxy derivatives of 9,10-anthraquinone such as chrysophanic acid (Ch), rhein (Rh) and emodin (Em) at mercury and glassy carbon electrodes using two different supporting electrolytes in chloroform is described. In the presence of piperidinium perchlorate (0.75M) + piperidine (0.25M) as a suitable acid supporting electrolyte, the reduction of Ch and Rh was a reversible two-electron process without complicating chemical reactions or adsorption phenomena, but the reduction process of these compounds in the presence of tetrabutylammonium perchlorate (TBAP) 0.5M + 5% acetic acid (AcOH) in chloroform was quasi-reversible. In both supporting electrolytes the overall reduction process of Em was irreversible. In the AC polarography and DP voltammetry at a GC electrode, the detection limit for Ch, Rh and Em was acceptably low and the relative standard deviation for the determination of 5 x 10(-6)M level, never exceeded 2%. AC polarography has been used for the determination of Ch and Em in a local rhubarb sample after extraction into chloroform and separation by column chromatography.